Aliso Viejo City Council
October 7, 2026

Table 1 Existing Uses
North Attached multi-family and single-family residential South Multi-tenant office buildings, light industrial
East Laboratories, fitness facilities, approved multi-family residential West Gas station, fast-food restaurant, auto repair shop, and Brookline Park
Proposed Project
The Applicant is proposing to redevelop the Site by demolishing the existing office building and developing a residential community consisting of 58 townhome units, which includes three units restricted to very low-income households. The Project details are provided in Table 2 below:

Table 2 Project Details
Number of Units
 58 units spread across 10 separate buildings. Each building will consist of five to six attached units.
 Three- and four-bedroom units measuring 1,320 to 1,827 square feet in size.

Building
Three-story townhomes, measuring 36’ max. height. The exterior of the building will have stucco finish, framed windows with faux shutters, recessed entryway, wrought iron balcony railings, hip and gable roofs with tile.

Parking
A total of 140 parking spaces (116 enclosed, 24 unenclosed) on site which exceeds the minimum required by State Density Bonus Law (SDBL). Each unit will have two enclosed private garages at ground floor level. Each garage will include additional areas for trash bins, water heater, and private storage. Driveways are not proposed. An additional 24 unenclosed guest parking spaces are provided on site.

Common Space
Open space of 9% consisting of 3,194 square feet of amenity areas (BBQ, shade structure, picnic tables, and dog park), and 14,092 square feet spread throughout the site as shared yards, paseos and landscaped areas. The Applicant requests a State Density Bonus Law (SDBL) concession to reduce the minimum common open space requirement from 25% as required by the AVMC to 9%.

Additionally, the 1.93 acres of existing open space slopes would be preserved.

Miscellaneous
Community will not be gated, however, the perimeter of the site will be secured with fencing and landscaped. Entrance to the site will be enhanced with paving, signage, and accent trees. Streetlights, bollards, and shade structure lighting will be designed with recessed, downward-facing light sources.
228

Table 2 Project Details
Grading Construction is anticipated to maintain existing grades and would result in approximately 473 cubic yards of soil export.

Infrastructure New onsite water lines, sewer lines, storm drains, underground storm water facility, and fire hydrants.

Entitlements
The Project requires approval of a General Plan Amendment, Zone Change, Vesting Tentative Tract Map, Site Development Permit, and Development Agreement.

Additionally, the Project qualifies for the State Density Bonus Program, and the Applicant is requesting specific waivers and concessions. Each of these components is discussed in detail below.

General Plan Amendment
The Applicant requests to change the existing office use to residential use to develop the Project. This requires an amendment to the General Plan land use designation from Business Park to Medium Density Residential. Pursuant to Aliso Viejo Municipal Code (“AVMC”) Section 15.78.020 (General Plan Amendments), the City Council must make the following findings prior to approving the general plan amendment:

1. Public Welfare. Approval of the amendment will not create conditions materially detrimental to the public health, safety, and general welfare.

While the Site is located within a larger business park area, it is situated in proximity to the recently approved 95 Argonaut residential development, which also involved the redevelopment of a business park use for residential use. Similar to 95 Argonaut, the proposed Project would introduce a three-story attached townhome development at a scale compatible with existing residential neighborhoods that are located directly north of the Site across Glenwood Drive, including both multi-family and single-family residential development. The proposed Project incorporates similar architectural features as 95 Argonaut and adjacent residential communities such as stucco exteriors, tile roofs, wrought-iron balconies, recessed entries, and shared open-space areas. As proposed, the Project incorporates architectural and site design elements that are generally consistent with the character of nearby residential development and would provide a transition between the surrounding residential neighborhoods and the remaining business park uses in the area. Both projects feature multi-story attached residential units with comparable architectural character, private garages, guest parking, landscaped common open space, and enhanced site entries.

Additionally, the Site is situated in an area with established infrastructure, including roads, utilities, and public services, that can adequately support residential development. As part of the environmental assessment, the Project required comprehensive studies addressing air quality, energy, greenhouse gas emissions, 229

biological resources, cultural resources, geotechnical conditions, hydrology and water quality, noise, and transportation impacts. As discussed further in the Environmental Assessment section below, these studies concluded that the Project would result in less-than-significant impacts with the implementation of proposed mitigation measures. The Project plans also cleared preliminary review by the Orange County Fire Authority (OCFA).

Furthermore, the Project aligns with the City’s housing goals by facilitating the development of new housing opportunities. Future construction on the Site will be subject to plan check review and inspection process to ensure full compliance with applicable building and safety standards. Therefore, this finding can be made.

2. Internal General Plan Consistency. The amendment is internally consistent with those goals, objectives, and policies of the general plan that are not being amended.

The proposed amendment is consistent with the goals and policies of the General Plan listed below in that it incorporates landscaping aligned with the City Councilapproved plant palette, emphasizing low-water, drought-tolerant species; features building materials, colors, and architectural design that are compatible with the surrounding residential communities; public benefit fees; proposes three affordable housing units restricted to very low-income households, thereby enhancing housing diversity and affordability; and introduces rezoning to facilitate residential development that includes affordable units in support of the City’s housing objectives. Therefore, this finding can be made.

In the General Plan, COS' refers to Conservation and Open Space policies, H' for Housing policies and goals, and 'LU' for Land Use policies.  Policy COS-1.2 Reduce the amount of water used for landscaping and increase use of native and low water plants. Maximize use of native, low-water plants for landscaping of areas adjacent to sidewalks or other impermeable surfaces.  Policy COS-4.2 Encourage and maintain high-quality architectural and landscaping designs that enhance or complement the community’s visual character.
 Policy COS-7.5 Ensure that new development provides park land and/or improvements at a fair share ratio, pursuant to the City’s Parkland Ordinance.  Goal H-1: Encourage a diversity of housing types and provide affordability levels within Aliso Viejo to meet the needs of community residents.  Policy H-1.1 Identify sites appropriate for the development of a variety of housing types and price ranges to meet the needs of all socioeconomic segments of the community through the disbursement of affordable units in projects.
 Policy H-1.2 Encourage through the use of density bonuses and rezoning to allow for residential development, development of affordable housing opportunities throughout the community, as well as development of housing for 230

elderly and low- and moderate-income households near public transportation services.
 Policy H-1.4 Ensure that a portion of future residential development is affordable to low- and very-low-income households by designating certain sites as having the potential to be used for residential uses.  Policy H-3.8 Review existing zoning policies and explore zoning changes to facilitate the development of affordable housing.
 Policy LU-12.2 As a condition upon new development, require payment of park fees and/or dedication and provision of parkland, recreation facilities and/or multi-use trails that improve the public and private recreation system.

3. Land Use Compatibility. In the case of amendments to the General Plan land use policy map, the new designation is compatible with the designations on nearby properties.

The Site is located at the edge of a larger business park and directly across from established multi-family and single-family residential neighborhoods. The proposed project is similar to a recently approved development at 95 Argonaut project, which is located on the same street within the same business park area.

Both projects involve the conversion of an office property to a residential townhome community and introduce a land use that is compatible with nearby residential neighborhoods. The adjacent multi-family development shares several characteristics with the Project, including large attached-unit buildings, stucco exteriors, tile roofing, wrought iron balconies, recessed entryways, and shared open space without private driveways. These similarities ensure architectural and functional continuity between the Project and existing residential uses. The proposed land use designation therefore complements the surrounding residential character. Therefore, this finding can be made.

4. Property Suitability. In the case of amendments to the general plan land use policy map, the new designation is suitable for the location, access, visual character and topography of the subject property.

The property is located along established roadways with adequate vehicular and pedestrian access and is supported by existing infrastructure, including utilities and public services, sufficient to accommodate residential development. The Site is generally flat within the developed portion, with sloped areas adjacent to Glenwood Drive and Aliso Creek Road. The proposed Project would retain the existing slope, utilize existing access from Argonaut, and incorporate site improvements consistent with applicable engineering and design standards. The proposed residential development includes architectural, landscaping, and site design elements that are similar to those found in nearby residential communities north of the Site, including attached residential development across Glenwood Drive and also the recently approved residential townhomes at 95 Argonaut. In addition, the Site is located between existing residential neighborhoods and surrounding 231

business park uses, making it suitable for the proposed Medium Density Residential land use designation. Therefore, this finding can be made.

Zone Change
In addition to the proposed General Plan amendment, the Project requires a zoning designation change for the Site from Business Park 2 to Medium Density Residential.

Pursuant to AVMC Section 15.78.040 (Zone Change and Prezoning), the City Council must make the following findings prior to approving the zone change. All these findings can be made, as evidenced in the above General Plan Amendment Findings.

1. Public Welfare. Approval of the zone change will not create conditions materially detrimental to the public health, safety and general welfare.

2. General Plan Consistency. The zone change is consistent with the goals, objectives, and policies of the general plan and any applicable specific plan.

3. Land Use Compatibility. The zone change is compatible with the zoning and land use on nearby properties.

4. Property Suitability. The zone change is suitable for the location, access, visual character and topography of the subject property.

Vesting Tentative Tract Map
Pursuant to the requirements of the California Subdivision Map Act (Gov. Code §§ 66410 et seq.) and Title 14 of the Aliso Viejo Municipal Code, no tentative map shall be approved unless the following findings of consistency with the General Plan and compliance with CEQA have been made.

1. The proposed map is consistent with the applicable General and Specific Plans.

The Site has a General Plan land use designation of Business Park. The Applicant proposes a General Plan Amendment to re-designate the property for Medium Density Residential, which allows for residential development of eight to 18 dwelling units per acre. The Vesting Tentative Tract Map proposes 58 multi-family homes on 4.4 acres, resulting in a density of 13.2 dwelling units per acre. As conditioned, the Vesting Tentative Tract Map will not take effect unless the General Plan Amendment, Zone Change, Site Development Permit, and Development Agreement take effect. Accordingly, the proposed map would be consistent with the applicable General Plan Land Use designation. There is no applicable Specific Plan for the Site. Therefore, this finding can be made.

2. The design or improvement of the proposed subdivision is consistent with the General and Specific Plans.
232

The Project is consistent with the goals and policies of the Conservation and Open Space, Housing, and Land Use element in that the Project promotes orderly growth, provides a compatible transition between non-residential and residential uses, supports housing objectives by creating new residential opportunities, and utilizes existing infrastructure in a manner consistent with the community’s longterm vision and planning framework. The Project is also subject to mitigation measures and conditions of approval that address potential impacts related to traffic, noise, air quality, and emergency access. There is no applicable Specific Plan for the Project site. Therefore, this finding can be made.

3. The site is physically suitable for the type of development.

The Site is generally level, has adequate access from existing public streets, and is served by established infrastructure systems including water, sewer, storm drainage, and utilities. The Site’s size, configuration, and surrounding land use context are appropriate to accommodate the Project consistent with applicable zoning and General Plan designations. No unusual topographic, geologic, or environmental conditions have been identified that would render the site unsuitable for residential use. Therefore, this finding can be made.

4. The site is physically suitable for the proposed density of development.

The Project includes a General Plan Amendment to re-designate the property to Medium Density Residential, which permits residential development at a range of eight to 18 dwelling units per acre. The Vesting Tentative Tract Map proposes 58 multi-family homes on 4.4 acres, resulting in a density of approximately 13.2 dwelling units per acre. This proposed density falls within the allowable range for the Medium-Density Residential designation. Therefore, this finding can be made.

5. The design of the subdivision and the proposed improvements are not likely to cause substantial environmental damage or substantial and avoidable injury to fish or wildlife or their habitat.

The Project site is currently developed with an office building, surface parking lot, and landscaping. There is no fish, wildlife, or any habitat that would be affected by the Project.

6. The design of the subdivision or type of improvements is not likely to cause serious public health problems.

The Project will be served by existing off-site infrastructure, with new on-site water, sewer, and storm drain facilities designed to connect to and extend those systems.

All facilities have adequate capacity to accommodate the proposed residential use.

The subdivision design incorporates standard improvements, including paved streets, sidewalks, street lighting, and utility connections that will be constructed in compliance with applicable building codes and City engineering standards. The 233

Initial Study prepared for the Project did not identify any conditions that would result in significant public health impacts, and all potentially significant effects have been mitigated to less-than-significant levels.

7. The design of the subdivision or the type of improvements will not conflict with existing easements, acquired by the public at large, for access through or use of property within the subdivision.

The Project as conditioned requires the Applicant to obtain easement holders’ authorization for any improvements or encroachments prior to building permit issuance.

8. The advisory agency shall determine whether the discharge of waste from the proposed subdivision into an existing sanitary sewer system would result in or add to a violation of existing requirements prescribed by either the Santa Ana or San Diego Regional Water Quality Control Boards.

The Initial Study/Mitigated Negative Declaration (IS/MND) identified the Moulton Niguel Water District (MNWD) collection system for treatment at existing regional treatment facilities and concluded that the project would not violate any water quality standards or waste discharge requirements, nor substantially degrade surface water or groundwater quality. In correspondence dated October 1, 2025, MNWD indicated that it will provide water, recycled water, and wastewater service to the proposed development and that a preliminary review suggests adequate water supply and sewer capacity are available to serve the project. The project remains subject to all applicable federal, State, regional, and local water quality regulations, including National Pollutant Discharge Elimination System requirements, implementation of the approved Water Quality Management Plan, and applicable Regional Water Quality Control Board regulations.

9. If the advisory agency approves or conditionally approves a tentative map which deviates from any standard of design as allowed by AVMC, the advisory agency shall make a finding that each such deviation has been individually considered and found to be justified based upon specific special circumstances.

No deviations from the subdivision design standards are proposed as part of the Vesting Tentative Tract Map. Accordingly, no deviations require consideration or justification based on special circumstances.

Site Development Permit
The purpose of a site development permit (“SDP”) is to ensure that new development conforms to the development and design provisions of the AVMC, including but not limited to permitted uses, development standards, and supplemental regulations.

Pursuant to AVMC Section 15.74.020 (Site Development Permits), the City Council must make the following findings prior to approving the SDP:
234

1. Consistency with General Plan. The Project is consistent with the general plan and any applicable specific plan.

The Project includes a General Plan Amendment (“GPA”). As detailed in the preceding GPA section, all required findings to support the amendment can be made.

2. Consistency with Zoning Code. The land use and associated development conform to the permitted use provisions and development standards of this zoning code and is consistent with this code and any applicable specific plan.

The proposed zone change to Medium Density Residential, together with the associated development, is compatible with surrounding land uses, providing a transition that complements the existing neighborhood character. The property is suitable for residential use based on its location, access, visual character, and topography, and existing infrastructure is adequate to support the proposed development. The Project includes requests for incentives, concessions, and waivers pursuant to California State Density Bonus Law (Government Code Section 65915). The Project provides three deed-restricted very low-income units, representing at least five percent of the total units, and therefore qualifies for consideration of the requested density bonus incentives and waivers. The requested modifications include a one-foot increase in building height, a reduction in common open space, reduced perimeter setbacks, and reduced minimum boundary landscaping standards.

In addition, the Project qualifies for a reduced parking requirement under State Density Bonus Law. Based on the applicable density bonus parking ratio, the Project is required to provide a minimum of 130 parking spaces. The Project proposes 140 parking spaces, consisting of 116 private residential parking spaces within garages and 24 unenclosed guest parking spaces, including one ADAaccessible space. Accordingly, the Project exceeds the minimum parking requirement established under State Density Bonus Law.

With these provisions, the Project conforms to the permitted use requirements and development standards of the zoning code and remains consistent with all applicable Specific Plan regulations. Therefore, this finding can be made.

3. Compliance with CEQA. Processing and approval of the permit application are in compliance with the requirements of the California Environmental Quality Act.

This finding can be made as evidenced in the Environmental Analysis below.

4. Architectural Design. The architectural design of the Project, including but not limited to the architectural style, scale, building mass, materials, colors, architectural details, and roof style, is compatible with surrounding development. 235

Directly north of the site are established multi-family and single-family residential communities. The adjacent multi-family development, in particular, shares several defining characteristics with the Project, including similarly scaled buildings composed of six attached units. The architectural style is complementary, featuring stucco exteriors, tile roofing, wrought iron balconies, recessed entryways, and communal open space without private driveways. The surrounding single-family tract homes also reflect a consistent architectural design, with comparable color palettes, exterior finishes, and material selections. The Project further enhances this compatibility through the inclusion of framed windows, some accented with faux shutters, as well as a mix of hip and gable roof forms, which reflects the roof styles found in nearby residences. The proposed Project consists of similar attached townhome units with comparable building massing, architectural features, private garages, guest parking, landscaped common open-space amenities as the recently approved 95 Argonaut development, further demonstrating architectural compatibility. Both projects are designed to transition former office properties to residential communities while maintaining architectural consistency with surrounding neighborhoods. Collectively, these design elements ensure compatibility with the surrounding development and this finding can be made.

5. Site Design. The site design of the Project, including but not limited to project entries, interior circulation, pedestrian and bicycle access, pedestrian amenities, screening of equipment and trash enclosures, exterior lighting, and other site design elements, is compatible with surrounding development.

Based on the analysis provided in the Initial Study and supporting documentation, the Project will retain the existing single-entry driveway at the southern end of the site along Argonaut. The internal private roadway system designed to provide twoway access to residential garages and guest parking spaces, emergency access, hydrant placement has been reviewed and conceptually approved by both the Building Division and the OCFA. Each unit will include an enclosed private garage with dedicated space for trash bin storage. Approximately 9% of the site will be dedicated to open space, including a private park, shared yards, pedestrian walkways, and perimeter landscaping. Perimeter fencing and exterior mechanical equipment will be screened with additional landscaping, and the site entrance will be enhanced with decorative paving, signage, and accent trees. Lighting throughout the site, including streetlights, bollards, and shade structures, will be designed with recessed, downward-facing fixtures to minimize light spill. These design elements are compatible with surrounding residential communities, and the required finding can be made.

6. Landscape Design. Project landscaping, including but not limited to the location, type, size, color, texture, and coverage of plant materials, has been designed so as to provide visual relief, complement buildings, visually emphasize prominent design elements and vistas, screen undesirable views, provide a harmonious 236

transition between adjacent land uses and between development and open space, and provide an overall unifying influence to enhance the visual continuity of the Project.

The Project incorporates a landscape plan that enhances the overall visual continuity of the site and complements the architectural character of the development. Existing landscaped slopes and mature screening trees along the northern and western boundaries will be preserved, maintaining established landscape buffers adjacent to Glenwood Drive and Aliso Creek Road. The Project provides common open-space amenities, including a community garden, dog play area, shade structure, barbeque area, pedestrian walkways, and landscaped gathering areas. In addition, approximately 7,611 square feet of private yard area is provided for individual residential units, and preserved open-space slope areas remain throughout the Site. Landscaping is also proposed around the exterior mechanical equipment and perimeter fencing to screen undesirable views. The site entrance is designed to create a welcoming and visually prominent focal point, enhanced with decorative paving, signage, and accent trees. The proposed landscaping aligns with the City Council-approved plant palette, emphasizing lowwater, drought-tolerant species. Therefore, this finding can be made.

Development Agreement
This Project requires land use and zoning changes from office to residential, which requires Development Agreement DA-2026-01002 (“DA”) to ensure the Project is implemented as approved, minimize potential adverse impacts, and secure long-term community benefits. Under the DA (Attachment 5, Exhibit A), the Applicant has agreed to contribute a one-time public impact fee of $2,057,651. Full payment must be made to the City prior to the issuance of any permit, and no permit will be issued until the City has received the payment and confirmed compliance with all applicable fee requirements.

Pursuant to AVMC 15.82.010 (Development Agreements and Other Actions), the City Council must make the following findings prior to approving the DA:

1. Public Welfare. Approval of the development agreement will not create conditions materially detrimental to the public health, safety and general welfare.

The Project is consistent with the policies and regulations of the proposed MediumDensity Residential zoning district. The DA includes provisions to ensure compliance with applicable land use regulations, defines the scope of the Project, and identifies the public benefit obligations of the Applicant. The Project is compatible with the existing and recently approved multi-family and single-family communities in terms of layout, architectural style, materials, and open space; the site is served by existing infrastructure, including roads, utilities, and public services sufficient to support residential development; that the environmental assessment determined impacts would be less than significant with mitigation; the Project advances the City’s housing goals by creating new housing opportunities; 237

and future construction will be subject to plan check review and inspection to ensure compliance with all applicable building and safety standards. Therefore, this finding can be made.

2. General Plan Consistency. The development agreement is consistent with the goals, objectives, and policies of the general plan and any applicable specific plan.

The Project is consistent with the goals and policies of the Conservation and Open Space, Housing, and Land Use elements in that the Project promotes orderly growth, provides a compatible transition between non-residential and residential uses, supports housing objectives by creating new residential opportunities, and utilizes existing infrastructure in a manner consistent with the community’s longterm vision and planning framework. The Project is also subject to mitigation measures and conditions of approval that address potential impacts related to biological resources, geology and soils, cultural and tribal resources, and hazards and hazardous materials. The DA incorporates, among other provisions, the scope of the Project, compliance with governing regulations, and the Applicant’s public benefit obligations, ensuring that this finding can be made.

Environmental:

Pursuant to the California Environmental Quality Act (“CEQA”) and the State CEQA Guidelines, the City prepared an Initial Study/Mitigated Negative Declaration (“IS/MND”) to evaluate the potential environmental impacts of the proposed Project. The analysis concluded that the Project could result in potentially significant environmental impacts; however, all such impacts can be reduced to less-than-significant levels through the implementation of mitigation measures. As a result, the City also prepared a Mitigation Monitoring and Reporting Program (“MMRP”) in compliance with CEQA.

The IS/MND was circulated for a 20-day public review period beginning on August 21, 2026. However, because the Notice of Intent was not posted at the County Recorder's Office until August 28, 2026, the public review period was extended by an additional seven days to ensure the full review period commenced upon posting. Accordingly, the IS/MND was available for public review from August 21 through September 17, 2026.

Distribution included the State Clearinghouse, required public agencies, property owners within a 300-foot radius of the Project site, and interested parties. One comment was received from the State Department of Transportation (Caltrans) (Attachment 1, Exhibit C), In its letter, Caltrans expressed support for the City's efforts to provide additional housing opportunities and acknowledged the relationship between transportation and land use planning. Caltrans provided recommendations related to bicycle parking, pedestrian and bicycle connectivity, Complete Streets features, electric vehicle infrastructure, delivery and truck circulation, and construction traffic management.

Caltrans did not identify any significant concerns regarding impacts on the State Highway System or request additional environmental analysis or mitigation measures. (Attachment 4, Exhibit A).
238

The IS/MND determined that the Project would not result in significant impacts to aesthetics, agricultural and forestry resources, air quality, energy, greenhouse gas emissions, hazards and hazardous materials, hydrology and water quality, land use and planning, mineral resources, noise, population and housing, public services, recreation, transportation, utilities and service systems, or wildfire. However, it identified potentially significant impacts to biological resources, cultural resources, tribal cultural resources, and geology and soils. With the implementation of mitigation measures, these impacts would be reduced to less than significant levels. The mitigation measures are detailed in the Mitigation Monitoring and Reporting Program (MMRP) (Attachment 1, Exhibit B) and have been incorporated into the Conditions of Approval (Attachment 4, Exhibit A) for the Project.

City Staff recommends that the City Council adopt the IS/MND and MMRP based on the findings set forth in the accompanying resolution. If the Project is approved, a Notice of Determination must be filed with the County Clerk and the State Clearinghouse within five working days of approval.

Attachments:

1. Resolution (Mitigated Negative Declaration)
a. Exhibit A – Initial Study/Mitigated Negative Declaration (ISMND) b. Exhibit B – Mitigation Monitoring and Reporting Program c. Exhibit C – Response to Comments

2. Resolution (General Plan Amendment)
a. Exhibit A – Amendment to the General Plan Land Use Map

3. Ordinance (Zone Change)
a. Exhibit A – Zone Change Map

4. Resolution (Vesting Tentative Tract Map and Site Development Permit) a. Exhibit A – Conditions of Approval
b. Exhibit B – Proposed Plans

5. Ordinance (Development Agreement)
a. Exhibit A – Development Agreement

6. Presentation
239

RESOLUTION NO. 2026-___

A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF ALISO

VIEJO, CALIFORNIA, ADOPTING MITIGATED NEGATIVE

DECLARATION AND A MITIGATION MONITORING AND REPORTING
PROGRAM (CEQA-2026-01004) PURSUANT TO THE CALIFORNIA

ENVIRONMENTAL QUALITY ACT FOR GENERAL PLAN AMENDMENT
GPA-2026-01002, ZONE CHANGE ZC-2026-01001, SITE
DEVELOPMENT PERMIT SDP-2026-01001, VESTING TENTATIVE
TRACT MAP 19489, AND DEVELOPMENT AGREEMENT 2026-01002
TO ALLOW THE DEVELOPMENT OF A 58-UNIT RESIDENTIAL
TOWNHOME COMMUNITY LOCATED AT 15 ARGONAUT (APN: 623-
093-10 & 623-093-11).

WHEREAS, On April 15, 2026, Brandywine Acquisition Group, LLC (“Applicant”) submitted a general plan amendment, zone change, vesting tentative tract map, site development permit, and a development agreement application to demolish an existing office building to accommodate the construction of a multi-family residential community at 15 Argonaut (“Project”);
WHEREAS, pursuant to the California Environmental Quality Act (Public Resources Code, § 21000 et seq.) and the State CEQA Guidelines (California Code of Regulations, title 14, § 15000 et seq.) (Collectively, “CEQA”), the City is the lead agency for the proposed Project;
WHEREAS, in accordance with State CEQA Guidelines section 15063, the City prepared an Initial Study to analyze whether the proposed Project may cause a potentially significant effect on the environment;
WHEREAS, based on the information contained in the Initial Study, which concluded that the proposed Project could have potentially significant impacts but that those impacts could be reduced to less than significant levels with implementation of proposed mitigation measures, the City determined that a Mitigated Negative Declaration (“MND”) should be prepared for the proposed Project;
WHEREAS, the Initial Study/Mitigated Negative Declaration (IS/MND) (State Clearinghouse Number [SCH] 2026080753) was prepared pursuant to CEQA and the State CEQA Guidelines;
WHEREAS, pursuant to CEQA, the City prepared a program for reporting on or monitoring the changes which it has either required in the proposed Project or made a condition of approval to mitigate or avoid potential significant environmental effects (the “Mitigation Monitoring and Reporting Program” or “MMRP”); WHEREAS, in accordance with State CEQA Guidelines sections 15072 and 15073, the IS/MND was circulated for public review beginning August 21, 2026 through September 240

17, 2026. However, because the Notice of Intent was not posted at the County Recorder's Office until August 28, 2026, the public review period was extended by an additional seven days to ensure the full review period commenced upon posting. Accordingly, the IS/MND was available for public review from August 21 through September 17, 2026; WHEREAS, the City received one comment from the California Department of Transportation (Caltrans), which the City has reviewed and responded to; WHEREAS, during the public review and comment period, copies of the IS/MND were available for review and inspection at the City of Aliso Viejo, Community Development Department and on the City’s website;
WHEREAS, the City has reviewed the final IS/MND, and relevant information contained in the record regarding the Project, and determined that all legal prerequisites to the adoption of the resolution have been met;
WHEREAS, on September 15, 2026, the City gave public notice of the City Council public hearing for consideration of Mitigated Negative Declaration CEQA-2026-01004, General Plan Amendment GPA-2026-01002, Zone Change ZC-2026-01001, Vesting Tentative Tract Map 19489, Site Development Permit SDP-2026-01001 and Development Agreement DA-2026-01002 for the Project by publishing in a newspaper of general circulation; posting notices at City Hall and the Project site; and mailing notices to owners of property within 300 feet, to the project applicant, and to local agencies that provide water, sewage, electricity and schools;
WHEREAS, on October 7, 2026, the City Council held a public hearing as prescribed by law and considered written and verbal public testimony that was submitted prior to the hearing and during the hearing, and evidence and recommendations presented by staff in the agenda report and oral presentation;
WHEREAS, no comments made in the public hearing conducted by the City, and no additional information submitted to the City, have resulted in substantial new information requiring substantial revisions that would trigger recirculation of the IS/MND or additional environmental review of the proposed Project under State CEQA Guidelines section 15073.5; and
WHEREAS, all other legal prerequisites to the adoption of this Resolution have occurred.

NOW, THEREFORE, BE IT RESOLVED BY THE CITY COUNCIL OF THE CITY OF ALISO VIEJO AS FOLLOWS:

Section 1. Incorporation of Recitals. The City Council hereby finds and determines that all of the recitals set forth above are true and correct. The above recitals are hereby incorporated as substantive findings of this Resolution. 241

Section 2: Compliance with CEQA. The City Council has reviewed and considered the information contained in the IS/MND, comments received, and other documents contained in the administrative record for the Project. The City Council finds that the IS/MND has been completed in compliance with CEQA, the State CEQA Guidelines, and the City’s Local CEQA Guidelines.

Section 3. Findings. Based on the whole record before it, including the IS/MND, the administrative record and all other written and oral evidence presented to the City Council, the City Council finds that all environmental impacts of the Project are either less than significant or can be mitigated to less than significant levels with the mitigation measures outlined in the IS/MND, and the Mitigation Monitoring and Reporting Program. The City Council finds that there is no substantial evidence in the administrative record supporting a fair argument that the Project may result in any significant environmental impact. The City Council finds that the IS/MND contains complete, objective, and accurate reporting of the environmental impacts associated with the Project and reflects the independent judgment and analysis of the City.

Section 4. Adoption of The Mitigated Negative Declaration. The City hereby approves and adopts the IS/MND, which is hereby attached to this Resolution as Exhibit “A.”
Section 5. Adoption of The Mitigation Monitoring And Reporting Program.

The City hereby adopts the MMRP, which is hereby attached to this Resolution as Exhibit “B.” In the event of any inconsistencies between the mitigation measures as set forth in the IS/MND and the MMRP, the MMRP shall control.

Section 6. Notice of Determination. The City directs Staff to prepare, execute, and file a Notice of Determination with the County Clerk and the State Clearinghouse within five (5) working days of the passage and adoption of this Resolution.

Section 7: Location of Documents. The administrative record for the Project is maintained at City Hall located at 12 Journey, Suite 100, Aliso Viejo, CA 92656. The custodian of records is the City Clerk.

Section 8. Execution of Resolution. The Mayor shall sign this Resolution, and the City Clerk shall attest and certify to the passage and adoption thereof.

PASSED, APPROVED AND ADOPTED this 7th day of October 2026. __________________________
Max Duncan, Mayor
APPROVED AS TO FORM: ATTEST:
242

__________________________ __________________________
Scott C. Smith, City Attorney Maria Kendig, City Clerk
243

STATE OF CALIFORNIA )
COUNTY OF ORANGE ) ss.

CITY OF ALISO VIEJO )
I, Maria Kendig, City Clerk of the City of Aliso Viejo, California, DO HEREBY CERTIFY that the foregoing is the original of Resolution No. 2026-__ duly passed and adopted by the City Council of the City of Aliso Viejo at their regular meeting held on the 7th day of October 2026, by the following roll call vote, to wit:

AYES:

NOES:

ABSENT:
___________________________

MARIA KENDIG, CITY CLERK

(SEAL)
244

Exhibit “A”
Initial Study/Mitigated Negative Declaration
245

Exhibit “B”
Mitigation Monitoring Program
246

Exhibit “C”
Response to Comments
247
15 Argonaut Project
Draft Initial Study/Mitigated Negative Declaration
City of Aliso Viejo, Orange County, California
PREPARED FOR:

City of Aliso Viejo
12 Journey, Suite 100
Aliso Viejo, CA 92656
949.425.2525
Contact: So Kim, Community Development Director
PREPARED BY:

FirstCarbon Solutions
250 Commerce, Suite 210
Irvine, CA 92602
714.508.4100
Contact: Cecilia So, Project Director
Tsui Li, Project Manager
August 21, 2026
•• • FCS
An ADEC Innovation
248

THIS PAGE INTENTIONALLY LEFT BLANK
249
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS iii
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Table of Contents
Acronyms and Abbreviations vii
1 - Introduction and Project Description 1

1.1 - Purpose 1

1.2 - Project Location 1

1.3 - Environmental Setting 1

1.4 - Project Description 7

1.4.1 - Land Use Designation and Zoning 7

1.4.2 - Surrounding Land Uses 7

1.5 - Required Approvals 21

1.6 - Intended Uses of This Document 21
2 - Environmental Checklist and Environmental Evaluation 23

2.1 Aesthetics 24

2.2 Agriculture and Forestry Resources 30

2.3 Air Quality 33

2.4 Biological Resources 49

2.5 Cultural Resources 55

2.6 Energy 61

2.7 Geology and Soils 65

2.8 Greenhouse Gas Emissions 76

2.9 Hazards and Hazardous Materials 82

2.10 Hydrology and Water Quality 91

2.11 Land Use and Planning 101

2.12 Mineral Resources 109

2.13 Noise 111

2.14 Population and Housing 120

2.15 Public Services 123

2.16 Recreation 130

2.17 Transportation 133

2.18 Tribal Cultural Resources 139

2.19 Utilities and Service Systems 145

2.20 Wildfire 154

2.21 Mandatory Findings of Significance 158
3 - List of Preparers 163
Appendix A: Air Quality, Energy, and GHG Supporting Information 250
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
iv FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Appendix B: Biological Resources Supporting Information Appendix C: Cultural Resources Supporting Information
Appendix D: Geology and Soils Supporting Information
Appendix E: Hazards and Hazardous Materials Supporting Information E.1 - Phase I Environmental Site Assessment
E.2 - Phase II Environmental Site Assessment
Appendix F: Hydrology and Water Quality Supporting Information F.1 - Water Quality Management Plan
F.2 - Drainage Report
Appendix G: Noise Supporting Information
Appendix H: Public Service Letters
H.1 - Orange County Fire Authority
H.2 - Orange County Sheriff’s Department
H.3 - Aliso Viejo Parks Services
H.4 - Capistrano Unified School District
H.5 - Orange County Public Libraries
Appendix I: Transportation Supporting Information
Tables
Table 1: Unmitigated Construction—Maximum Daily Regional Emissions by Year 38 Table 2: Maximum Daily Operational Regional Pollutants 40 Table 3: Construction Localized Significance Screening Analysis 43 Table 4: Operational Localized Screening Significance Analysis 44 Table 5: Screening Levels for Potential Odor Sources 47 Table 6: Proposed Project Construction Greenhouse Gas Emissions 78 Table 7: Operational Greenhouse Gas Emissions—Unmitigated 79 Table 8: Project Consistency with Applicable General Plan Policies 102 Table 9: Existing Ambient Noise Levels on the Project Site 112 Table 10: Residential Noise Standards 113
Table 11: Exterior Noise Standards 114
Table 12: Multiple Dry Year Supply and Demand Comparison (AFY) 148 Table 13: Current Projects in the Vicinity of the Proposed Project 160 251
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS v
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Exhibits
Exhibit 1: Regional Location Map 3
Exhibit 2: Local Vicinity Map 5
Exhibit 3: General Plan Land Use Map 9
Exhibit 4: Zoning Map 11
Exhibit 5: Site Plan 15
Exhibit 6: Exterior Elevations 17
252

THIS PAGE INTENTIONALLY LEFT BLANK
253
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS vii
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx

ACRONYMS AND ABBREVIATIONS
AB Assembly Bill
ACM asbestos-containing material
ADA Americans with Disabilities Act
ADT Average Daily Traffic
AERMOD American Meteorological Society/EPA Regulatory Model AFY acre-feet per year
APN Assessor’s Parcel Number
AQMP Air Quality Management Plan
ARB California Air Resources Board
AVCA Aliso Viejo Community Association
AVTIG Aliso Viejo Transportation Impact Guidelines
Basin Plan Water Quality Control Plan for the San Diego Basin BERD Built Environment Resource Directory
bgs below ground surface
BMP Best Management Practice
Cal/EPA California Environmental Protection Agency
CAL FIRE California Department of Forestry and Fire Protection CalEEMod California Emissions Estimator Model
CALGreen California Green Building Standards Code
Cal/OSHA Division of Occupational Safety and Health
CalRecycle California Department of Resources Recycling and Recovery Caltrans California Department of Transportation
CASQA California Stormwater Quality Association
CBC California Building Standards Code
CCR California Code of Regulations
CDFW California Department of Fish and Wildlife
CEQA California Environmental Quality Act
CESA California Endangered Species Act
cfs cubic feet per second
CGS California Geologic Survey
CHL California Historic Landmarks
CNDDB California Natural Diversity Database
CNEL Community Noise Equivalent Level
254
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
viii FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx CNPS California Native Plant Society
CNPS Inventory CNPS Inventory of Rare plants
CO carbon monoxide
CO2e carbon dioxide equivalent
COA Condition of Approval
CPHI California Points of Historical Interest
CPTED Crime Prevention Through Environmental Design
CRHR California Register of Historical Resources
CUSD Capistrano Unified School District
CVC California Vehicle Code
cy cubic yard
DAMP Drainage Area Management Plan
dB decibels
dBA A-weighted decibels
DOF California Department of Finance
DPM diesel particulate matter
DPR California Department of Parks and Recreation
DTSC California Department of Toxic Substance Control
du/acre dwelling units per acre
EMFAC Emission Factors mobile source emissions model
EOP Emergency Operations Plan
EPA United States Environmental Protection Agency
ESA Environmental Site Assessment
EV electric vehicle
EVSE electric vehicle supply equipment
FCS FirstCarbon Solutions
FEMA Federal Emergency Management Agency
FGC Fish and Game Code
FHSZ Fire Hazard Severity Zone
FHWA Federal Highway Administration
FMMP Farmland Mapping and Monitoring Program
FTA Federal Transit Administration
GAMAQI Guidance for Assessing and Mitigating Air Quality Impacts GHG greenhouse gas
GIS Geographic Information System
GPA General Plan Amendment
255
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS ix
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx GPCD gallons per capita per day
GPD gallons per day
HARP2 Hotspots Analysis and Reporting Program
HCP Habitat Conservation Plan
HDR High Density Residential
HRA Health Risk Assessment
HQTA High-quality Transit Area
HVAC heating, ventilation, and air conditioning
iDigBio Integrated Digitized Biocollections
in/sec inch per second
IPaC Information for Planning and Consultation
IS/MND Initial Study/Mitigated Negative Declaration
kWh kilowatt hours
LAFCo Local Agency Formation Commission
LBP lead-based paint
lbs pounds
Ldn day/night sound level
Leq equivalent continuous sound level
LID Low Impact Development
Lmax maximum instantaneous noise level
LOS Level of Service
LRA Local Responsibility Area
LST localized significance threshold
LUST Leaking Underground Storage Tank
MBTA Migratory Bird Treaty Act
MEP Maximum Extent Practicable
MDR Medium-Density Residential
MGD million gallons per day
MLD Most Likely Descendant
MM Mitigation Measure
MNWD Moulton Niguel Water District
mph miles per hour
MPO Metropolitan Planning Organization
MS4 Municipal Separate Storm Sewer System
MT metric tons
Metropolitan Metropolitan Water District of Southern California 256
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
x FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx MWDOC Municipal Water District of Orange County
NAHC Native American Heritage Commission
NCCP Natural Community Conservation Plan
NFHL National Flood Hazard Layer
NHM Natural History Museum of Los Angeles County
NOX nitrogen oxides
NPDES National Pollutant Discharge Elimination System
NRCS Natural Resources Conservation Service
NRHP National Register of Historic Places
OCFA Orange County Fire Authority
OCSD Orange County Sheriff’s Department
OCTA Orange County Transportation Authority
OEHHA California Office of Environmental Health Hazard Assessment PM10 particulate matter less than 10 microns in diameter PM2.5 particulate matter less than 2.5 microns in diameter ppm parts per million
PPV peak particle velocity
PRIMP Paleontological Resources Impact Mitigation Program PV photovoltaic
PWQMP Preliminary Water Quality Management Plan
RCRA Resource Conservation and Recovery Act
REC Recognized Environmental Condition
RHNA Regional Housing Needs Assessment
RM Residential–Medium Density
RTP/SCS Regional Transportation Plan/Sustainable Communities Strategy RWQCB Regional Water Quality Control Board
SB Senate Bill
SCAG Southern California Association of Governments
SCCIC South Central Coastal Information Center
SCE Southern California Edison Company
SEMS Standardized Emergency Management System
SIP State Implementation Plan
SLF Sacred Lands File
SoCAB South Coast Air Basin
South Coast AQMD South Coast Air Quality Management District SoCalGas Southern California Gas Company
257
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS xi
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx SOCWA South Orange County Wastewater Authority
SO2 sulfur dioxide
SOx sulfur oxides
SR State Route
SRA State Responsibility Area
SRRE Source Reduction and Recycling Element
State Water Board California State Water Resources Control Board SVP Society of Vertebrate Paleontology
SWIS Solid Waste Information System
SWMP Storm Water Management Plan
SWP State Water Project
SWPPP Storm Water Pollution Prevention Plan
TAC toxic air contaminant
TCR Tribal Cultural Resource
The Nat San Diego Natural History Museum
TK Transitional Kindergarten
TPA transit priority area
TTM Tentative Tract Map
UCMP University of California Museum of Paleontology
USACE United States Army Corps of Engineers
USDA United States Department of Agriculture
USFWS United States Fish and Wildlife Service
USGS United States Geological Survey
UST underground storage tank
UWMP Urban Water Management Plan
Valley Air District San Joaquin Valley Air Pollution Control District VEC Vapor Encroachment Condition
VHFHSZ Very High Fire Hazard Severity Zone
VMT Vehicle Miles Traveled
VOC volatile organic compound
VTTM Vesting Tentative Tract Map
WEAP Worker Environmental Awareness Program
WQIP Water Quality Improvement Plan
WQMP Water Quality Management Plan
WSS Web Soil Survey
WUI wildland urban interface
258

THIS PAGE INTENTIONALLY LEFT BLANK
259
15 Argonaut Project
Initial Study/Mitigated Negative Declaration
FCS 1
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx 1 - INTRODUCTION AND PROJECT DESCRIPTION

1.1 - Purpose
The purpose of this Draft Initial Study/Mitigated Negative Declaration (Draft IS/MND) is to identify any potential environmental impacts that would result from implementation of the 15 Argonaut Project (proposed project) in the City of Aliso Viejo, California. Pursuant to California Environmental Quality Act (CEQA) Guidelines Section 15367, the City of Aliso Viejo (City) has discretionary authority over the proposed project and is the Lead Agency in the preparation of this Draft IS/MND and any additional environmental documentation required for the project.

The remainder of this section provides a brief description of the project location and the primary project characteristics. Section 2 includes an environmental checklist that provides an overview of the potential impacts that may result from project implementation, elaborates on the information contained in the environmental checklist, and provides justification for each checklist response.

Feasible mitigations are analyzed to reduce all impacts to below a level of significance. Section 3 contains the List of Preparers.

1.2 - Project Location
The project site is located at 15 Argonaut, in the City of Aliso Viejo, in Orange County, California (see Exhibit 1) at the southeast corner of Glenwood Drive and Aliso Creek Road. The approximately 4.4- acre project site consists of two parcels (Assessor’s Parcel Number [APN] 623-093-10 and 623-093- 11). As shown in Exhibit 1, the project site is located in the northern portion of the City. Regional access to the project site is from Interstate 5 (I-5) via the El Toro Road exit and from State Route (SR) 73 via the Glenwood Drive exit.

1.3 - Environmental Setting
The project site is currently developed with an office building and a paved surface parking lot surrounding the building (Exhibit 2). The office building is approximately 41,519 square feet and 30 feet tall and currently unoccupied. The project site is relatively flat, with the exception of the northern and western portions of the project site, which include landscaped slopes ascending toward Glenwood Drive and Aliso Creek Road. Vehicular access is currently provided via a driveway at the southeastern corner of the site on Argonaut. Access to Argonaut is provided from Glenwood Drive and Aliso Creek Road.
260

THIS PAGE INTENTIONALLY LEFT BLANK
261
15 ARGONAUT PROJECT

INITI A L S TUD Y/M ITI GA TED NE GA TI V E DE C L ARA TI O N ' '
9- s_a_n_t'-a-1--_
Fofmta in"
Pacific Ocean
Legend
~ City of Aliso Viejo
Source: Census Data. The California Spatial Information Library (CaSIL). City of Aliso Viejo. 5 2.5 0 5
Miles
FCS
+-- .. +-- f--,;=-....,i,-~--!""'-J
~ ; 9 l .-·-·j1
,-· r- _J
..1-I I , I
' J
Modjeska I
El Toro
'-.. - .. - .. - ........

Cleveland National Forest '
/
.
/
.
/
/
.

Exhibit 1
Regional Location Map
65130001 • 03/2026 I 1_regional.aprx
262

THIS PAGE INTENTIONALLY LEFT BLANK
263
15 ARGONAUT PROJECT

INITIAL STUDY / MITIGATED NEGATIVE DECLARATION
Source: ESRI World Imagery. Advanced Civil Group Inc. March 20th, 2026. 1,000 500
FCS
0 1,000
Feet
Exhibit 2
Local Vicinity Map
65130001 • 03/2026 I 2_Iocal_vicinity.aprx
264

THIS PAGE INTENTIONALLY LEFT BLANK
265
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 7
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx

1.4 - Project Description

1.4.1 - Land Use Designation and Zoning
The City of Aliso Viejo General Plan (General Plan) designates the project site as Business Park (Exhibit 3).1 As shown in Exhibit 3, adjacent to the western border of the project site is land designated as Open Space. No changes are proposed that would change or affect the area designated as Open Space. The proposed project applicant requests a General Plan Amendment (GPA) to change the General Plan land use designation from Business Park to Medium-Density Residential (MDR). The MDR land use designation is intended to provide residential development with a density between 8 and 18 dwelling units per gross acre (du/acre), with an average density of 12 du/acre.2
The project site is currently zoned Business Park-2 (Exhibit 4). The proposed project applicant requests a rezone to change the designation from Business Park-2 to Residential–Medium Density (RM) District. The RM zoning district is intended to provide for the development and preservation of medium density neighborhoods containing detached and attached single-family homes on smaller lots, duplexes, townhomes, apartments, and condominiums (Aliso Viejo Municipal Code [Municipal Code] Chapter 15.10). Each project is required to have ample common open space and recreational facilities. The maximum density is 18 du/acre.3

1.4.2 - Surrounding Land Uses
North
• Existing Land Uses: Glenwood Drive and single-family residential community • General Plan Land Use Designation: Very Low Density Residential and High Density Residential
• Zoning: Specific Plan – Glenwood
South
• Existing Land Uses: Argonaut and multi-tenant office buildings • General Plan Land Use Designation: Business Park
• Zoning: Business Park-2
1 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element, Land Use Policy Map, Figure LU-1.

Website: http://avcity.org/DocumentCenter/View/397/Land-Use-Policy-Map-PDF. Accessed April 10, 2026. 2 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element. Website:
https://avcity.org/DocumentCenter/View/391/Land-Use-Element-PDF. Accessed April 10, 2026. 3 Ibid.
266
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
8 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx East
• Existing Land Uses: Argonaut, two office buildings, and planned residential community • General Plan Land Use Designation: Business Park and High Density Residential • Zoning: Business Park-2 and Residential High Density
West
• Existing Land Uses: Aliso Creek Road, gas station, fast-food restaurant, auto repair shop, and Brookline Park
• General Plan Land Use Designation: Neighborhood Commercial and Recreation • Zoning: Neighborhood Commercial and Open Space Recreation 267
1 5 A R G O N A U T P R O J E C T

I N I T I A L S T U D Y / M I T I G A T E D N E G A T I V E D E C L A R A T I O N 65130001 • 04/2026 | 3_GPLU.aprx
Exhibit 3
Source: ESRI World Imagery. Advanced Civil Group Inc. March 20th, 2026. County of Aliso Viejo. ¥
1,000 500 0 1,000
Feet
F C S
General Plan Land Use Map
Pacific
Park Dr
Eastwing
Enterprise
Aliso Creek Rd
Glenwood Dr
Cedarbrook
Moulton
Pkwy
Argonaut
OS
R
R
R
R
R
R
R
R
OS
OS
OS
LDR
LDR
LDR
LDR
MDR
MDR
MDR
MDR
MDR
MDR
MDR
MDR
VHDR
MDR
MDR
OS
CF
CF
LDR
R
MDR
R
CF
OS
VHDR
HDR/PO
CC
VLDR
HDR
HDR
HDR
HDR
HDR
HDR
HDR
PO
PO
PO
BP
BP
BP
BP
BP
BP
BP
LDR
LDR
LDR

LDR LDR
LDR

LDR LDR
LDR

LDR LDR

LDR LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
HDR
HDR
NC
HDR
NC
HDR
Glenwood Dr
Aliso Creek Rd
Argonaut
BP
BP
BP
VLDR
NC
OS
·|þ}73
Legend
Project Site 4.40 acres
Off-Site Improvement 0.006 acre
General Plan Land Use Designations
VLDR: Very Low Density Residential (Max. 5 units/acre)
LDR: Low Density Residential (Max. 8 units/ acre)
MDR: Medium Density Residential (Max. 18 units/ acre)
HDR: High Density Residential (Max. 30 units/ acre)
VHDR: Very High Density Residential (Max. 50 units/ acre) TCC: Town Center Commercial
CC: Community Commercial
NC: Neighborhood Commercial
BP: Business Park
PO: Professional Office
CF: Community Facilities
R: Recreation
OS: Open Space
HDR/PO: Mixed Use-High Density Residential/ Professional Office HDR/TCC: Mixed Use-High Density Residential/ Town Center Commercial MDR/PO: Mixed Use-Medium Density Residential/ Professional Office PO/CC: Mixed Use-Professional Office/ Community Commercial VHDR/BP: Mixed Use-Very High Density Residential/ Business Park -
D
D
D
D
D
~
rza
~
rza
268

THIS PAGE INTENTIONALLY LEFT BLANK
269
1 5 A R G O N A U T P R O J E C T

I N I T I A L S T U D Y / M I T I G A T E D N E G A T I V E D E C L A R A T I O N 65130001 • 03/2026 | 4_zoning.aprx
Exhibit 4
Source: ESRI World Imagery. Advanced Civil Group Inc. March 20th, 2026. County of Aliso Viejo. ¥
1,000 500 0 1,000
Feet
F C S
Zoning Map
Pacific
Park Dr
Eastwing
Enterprise
Aliso Creek Rd
Glenwood Dr
Cedarbrook
Moulton
Pkwy
Argonaut
OS-P
R
OS-R
OS-P
RM
RM
RM
RVHD
RM
RM
OS-P
CF
CF
RM
RL RL
RL RL
SP-4 SP-3 SP-3
RM
RL
RL
RL RL
RL
RL RL
RL
RL
RL
RL
RL
RL
RL
RM
RM RM
RM
OS-P
OS-P
OS-P
OS-P
PO
PO
OS-R
OS-R
OS-R
OS-R
OS-R
R
CF
HDR
RHD
HDR
HDR
RHD
HDR
PO
PO
PO
BP
BP
BP-2
BP-2
BP-2
BP-2
BP-2
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
LDR
HDR
NC
RHD
Glenwood Dr
Aliso Creek Rd
Argonaut
BP-2
BP-2
BP-2
SP-3
NC
OS-P
Legend
Project Site 4.40 acres
Off-Site Improvement 0.006 acre
City of Aliso Viejo
Zoning Designations
RL: Residential Low Density
RM: Residential Medium Density
RHD: Residential High Density
RVHD: Residential Very High Density
NC: Neighborhood Commercial
BP-2: Business Park 2
PO: Professional Office
CF: Community Facilities
OS-R: Open Space Recreation
OS-P: Open Space Preservation
SP-3: Specific Plan: Glenwood
SP-4: Specific Plan: Ventana Ridge
·|þ}73
-
- ..
..
..
..
..
..
..
..
... ...
-
270

THIS PAGE INTENTIONALLY LEFT BLANK
271
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 13
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Brandywine Homes (applicant) proposes to demolish the existing approximately 41,519-square-foot two-story office building, the existing parking lot, and associated landscaping and develop a new residential infill community consisting of 58 3-story townhomes within 10 buildings. The proposed project’s density would be 13.2 du/acre, which would comply with the maximum density allowed by the MDR land use designation (18 du/acre). The townhomes would range in size from approximately 1,320 to 1,827 square feet and would offer an array of three- and four-bedroom floorplans (Exhibit 5).

The townhomes would be a maximum height of 36 feet (Exhibit 6) and would have a total building square footage of 94,061 square feet and a total building footprint of 44,924 square feet.

Five different architectural building types, two different types of 5-plex buildings and three different types of 6-plex buildings each include their own color scheme to create variety within the community.

Every home is designed to feature an individual entry front door and oversized decks to reinforce the strong indoor-outdoor lifestyle of the City. The color schemes include terracotta-colored roof tiles, with earth-tone palette trim accents such as browns and blues.

The existing screening trees along the western and northern perimeters of the project site would be preserved. During project site grading, existing ornamental landscaping and trees located within the interior developed areas would be removed. Nearly all trees removed by the proposed project would be replaced.

The proposed project would include private roadways and parking, pedestrian walkways, landscaping, and recreational amenity areas.

The proposed project would also include 5 percent deed-restricted affordable homes (three very-lowincome homes), and, accordingly, the applicant seeks the following concessions and waivers pursuant to the State’s Density Bonus Law:
• Open space concession
- Reduction of required open space from 25 percent of total site area (Municipal Code Section

15.10.030 residential development standards) to 9 percent. • Parking standard concession
- Provide 140 parking spaces, which is below the 145 parking spaces required pursuant to the Municipal Code, but exceeds the 130 parking spaces required under the State’s Density Bonus Law.
• Maximum building height waiver
- Increase building height from 35 feet to 36 feet.
• Minimum perimeter setbacks waiver
- Reduction of perimeter setbacks from the required 20 feet to a range of five feet and 14.9 feet in certain locations.
• Minimum boundary landscaping waiver
- Modification of landscaping boundaries from a minimum of 15 feet (20 feet average) to:
○ greater than 20 feet along the majority of the project site boundary; and ○ five feet in areas where perimeter setbacks are reduced. 272

THIS PAGE INTENTIONALLY LEFT BLANK
273
F C S 65130001 • 07/2026 | 5_site_plan.cdr
Site Plan
Exhibit 5
Source: WHA. 07/20/2026.

I N I T I A L S T U D Y / M I T I G A T E D N E G A T I V E D E C L A R A T I O N 1 5 A R G O N A U T P R O J E C T
\
an
·' .1n
\
Project Summary
Gross Site Area: ±4.4 Acres
Net Site Area: ±2.47 Acres
Total Units: 58 Homes
• (03) Plan 1 I ±1,320 SF 13 BO 13 BA I Tandem Garage
• (12) Plan 21 ±1,538 SF 13 BO 12.5 BA
• (28) Plan 3 I ±1,580 SF 14 BO 13.5 BA
• (15) Plan 41 ±1,827 SF 14 BO 13.5 BA
Total Saleable SF: 94,061 SF
Gross Density: 13.2 Homes per Acre
Net Density: 23.5 Homes per Acre
Parking:

Required: 130 Spaces (per State Density Bonus Law)
• 22.5 spaces (1.5 spaces per 3 bedroom unit)
• 107.5 spaces (2.5 spaces per4 bedroom unit)
Provided: 140 Spaces (2.41 spaces per home)
• Garage: 116 Spaces
( • Head in: 24 Spaces (incl. 1 accessible space)
\ @: Guest Spaces 6.: Accessible Space
, Common Usable Open Space:

Required: ±47,955 SF (25% of site area)
Provided: ±17,214 SF (9%)
) - • ±3, 194 SF (Amenity Spaces)
• ±14,020 SF (Paseos & Landscaped Areas)
Additonal Open Space Provided:
• ±7,611 SF (Private Yards)
- • ±84,050 SF (Additional open space dedicated to slope~ ±1.93 acres) ~
02040 80
\~
'\ \_
~
~ .
274

THIS PAGE INTENTIONALLY LEFT BLANK
275
F C S 65130001 • 07/2026 | 6_exterior_elevations.cdr
Exterior Elevations
Exhibit 6
Source: WHA. 07/20/2026.

I N I T I A L S T U D Y / M I T I G A T E D N E G A T I V E D E C L A R A T I O N 1 5 A R G O N A U T P R O J E C T
Right Rear
Left Color Scheme 2 Front
276

THIS PAGE INTENTIONALLY LEFT BLANK
277
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 19
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Parking and Circulation
Vehicles would access the project site via the existing driveway located at the southeastern corner of the project site along Argonaut. An internal private roadway system would provide access to each unit’s parking garage as well as to guest parking spaces that would be distributed throughout the site.

The proposed project has been designed to comply with applicable emergency service provider access standards, including fire department access, turning radii (an inner radius of 20 feet and outer radius of 49 feet), and emergency response requirements. Pedestrians would circulate within the site via proposed internal pedestrian walkways and sidewalks.

The proposed project would have 140 on-site parking spaces, consisting of 116 spaces within garages (two per unit) and 24 guest spaces (including one Americans with Disabilities Act [ADA]- accessible stall). Accordingly, the proposed parking spaces would exceed the parking ratio requirement of 130 total parking spaces pursuant to a concession in accordance with the State Density Bonus Law.

Open Space and Landscaping
The proposed project would include 17,214 square feet of common usable open space, which would include amenities such as a dog play area, a community garden, a recreation/yoga lawn, and a barbeque area with an accompanying shade structure. The proposed dog play area would be enclosed with a 4-foot-high steel fence. Additionally, the proposed project would include approximately 7,611 square feet of private yard areas associated with individual residential units.

The proposed project also includes approximately 84,050 square feet of existing open space located on the northern and western portions of the site that would be preserved as part of the proposed project. These preserved areas consist of steeply sloped terrain and are intended to remain in a natural, undeveloped condition for visual buffering and site design purposes. Because these areas do not meet the City’s definition of usable open space, they do not count toward the Municipal Code’s minimum open space requirement.

The Municipal Code requires usable open space to equal 25 percent (approximately 47,955 square feet) of the total site area (approximately 191,664 square feet). 4 The proposed project would include
17,214 square feet of common open space, representing approximately 9 percent of the total site area. Accordingly, the project applicant is requesting an open space concession pursuant to the State Density Bonus Law.

For informational purposes, the proposed common open space and private yards, when combined with the preserved existing open space areas, would total approximately 108,875 square feet of open space on the project site.
4 The project site is 4.40 acres in size (approximately 191,664 square feet). Twenty-five percent of the total site is, therefore, approximately 47,955 square feet.
278
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
20 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Along the eastern and southern perimeter of the project site, a 5-foot-9-inch wall is proposed. Two monument signage features would be installed at the entrance of the community that would be 7 feet 6 inches high.

The proposed project includes a comprehensive landscape plan featuring substantial streetscape and perimeter planting areas, internal landscaped paseos, private yard landscaping, and enhanced entry features. Landscaping will consist of a variety of canopy, ornamental, and screening trees, along with drought-tolerant shrubs, groundcovers, grasses, and vines designed to enhance the visual character of the community while supporting water-efficient design principles. Landscape screening would be provided around walls, utilities, and project site boundaries, including evergreen hedges and ornamental planting areas.

Infrastructure and Utilities
Water service is currently provided by Moulton Niguel Water District (MNWD).5 The proposed project would connect to existing water lines within Argonaut.

Wastewater is collected via the MNWD’s wastewater collection system and is sent to its Regional Treatment Plant in Laguna Niguel.6 The proposed project would connect to existing sanitary sewer lines within Argonaut.

The project site is currently served by existing storm drain infrastructure located within the adjacent public rights-of-way along Argonaut and the surrounding street network. The proposed project would incorporate an on-site stormwater collection system consisting of catch basins, underground storm drain lines, and water quality treatment facilities such as a biotreatment system designed to convey and manage runoff generated by the project. Runoff would be collected from rooftops, drive aisles, parking areas, and landscaped areas and directed through the proposed drainage system prior to discharge to the existing public storm drain network.

Additionally, the proposed project would install a fire hydrant consistent with fire flow requirements, in accordance with California Fire Code guidelines stipulated in Municipal Code Chapter 13.04, Fire Regulations, and would connect to existing water lines.

Each of the 58 townhomes would be solar-powered and all-electric.

Construction
Construction is anticipated to begin in March 2027 and would be completed by November 2028.

Construction is anticipated to occur across five phases: Model Phase (Building 1 and access driveway), Phase 1 (Buildings 2 and 3), Phase 2 (Buildings 4, 5, and 6), Phase 3 (Buildings 7 and 8), 5 Moulton Niguel Water District (MNWD). 2026. Serving South Orange County Since 1960. Website:
https://www.mnwd.com/servicearea/. Accessed April 10, 2026. 6 Moulton Niguel Water District (MNWD). 2026. Wastewater Collection and Treatment. Website:
https://www.mnwd.com/wastewater-treatment/. Accessed April 10, 2026. 279
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 21
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx and Phase 4 (Buildings 9 and 10). It is anticipated that project construction would maintain the existing grades as close as possible and result in approximately 473 cubic yards of soil export.

1.5 - Required Approvals
The City of Aliso Viejo has discretionary authority over the proposed project and is the CEQA Lead Agency for the preparation of this Draft IS/MND. In order to implement the proposed project, the applicant would need to secure the following permits/approvals:
• General Plan Amendment to change the land use designation from Business Park to MDR (density of up to 18 du/acre).
• Rezone to change the zoning from Business Park-2 to RM (density of up to 18 du/acre). • Vesting Tentative Tract Map (VTTM) for construction of 58 residential townhomes. • Site Development Permit and Development Agreement for building construction. • Concessions and Waivers pursuant to the State’s Density Bonus Law:
- Open space concession
- Parking standard concession
- Maximum building height waiver
- Minimum perimeter setbacks waiver
- Minimum boundary landscaping waiver
Additionally, ministerial permits would be required to implement the proposed project.

1.6 - Intended Uses of This Document
This Draft IS/MND has been prepared to determine the appropriate scope and level of detail required in completing the environmental analysis for the proposed project. This document will also serve as a basis for soliciting comments and input from members of the public and public agencies regarding the proposed project.

The Draft IS/MND will be circulated for a minimum of 20 days, during which comments concerning the analysis contained in the Draft IS/MND should be sent to:

So Kim, Community Development Director
City of Aliso Viejo Planning Services
12 Journey, Suite 100
Aliso Viejo, CA 92656
Phone: 949.497.2527
Email: [email protected]
280

THIS PAGE INTENTIONALLY LEFT BLANK
281
15 Argonaut Project
Initial Study/Mitigated Negative Declaration
FCS 21
Https://adecinnovations.sharepoint.com/sites/ESSite/Shared Documents/ES/Active Projects/6513 Brandywine Homes/0001 15 Argonaut/DOCUMENT/01 - ISMND/04 - ISMND Public Review Draft/65130001 Aliso Viejo 15 Argonaut Project ISMND_De Novo Review (4).docx
2 - ENVIRONMENTAL CHECKLIST AND

ENVIRONMENTAL EVALUATION
Environmental Factors Potentially Affected
The environmental factors checked below would be potentially affected by this project, involving at least one impact that is a “Potentially Significant Impact” as indicated by the checklist on the following pages.

Aesthetics Agriculture and Forestry Resources Air Quality Biological Resources Cultural Resources Energy
Geology and Soils Greenhouse Gas Emissions Hazards and Hazardous Materials
Hydrology and Water Quality Land Use and Planning Mineral Resources Noise Population and Housing Public Services
Recreation Transportation Tribal Cultural Resources
Utilities and Services
Systems
Wildfire Mandatory Findings of
Significance
Environmental Determination
On the basis of this initial evaluation:

I find that the proposed project COULD NOT have a significant effect on the environment, and a NEGATIVE DECLARATION will be prepared.

I find that although the proposed project could have a significant effect on the environment, there will not be a significant effect in this case because revisions in the project have been made by or agreed to by the project proponent. A MITIGATED NEGATIVE DECLARATION will be prepared.

I find that the proposed project MAY have a significant effect on the environment, and an ENVIRONMENTAL IMPACT REPORT is required.

I find that the proposed project MAY have a “potentially significant impact” or “potentially significant unless mitigated” impact on the environment, but at least one effect 1) has been adequately analyzed in an earlier document pursuant to applicable legal standards, and 2) has been addressed by mitigation measure based on the earlier analysis as described on attached sheets. An ENVIRONMENTAL IMPACT REPORT is required, but it must analyze only the effects that remain to be addressed.

I find that although the proposed project could have a significant effect on the environment, because all potentially significant effects (a) have been analyzed adequately in an earlier EIR or NEGATIVE DECLARATION pursuant to applicable standards, and (b) have been avoided or mitigated pursuant to that earlier EIR or NEGATIVE DECLARATION, including revisions or mitigation measures that are imposed upon the proposed project, nothing further is required.

Date: Signed: 8/18/2026
□
□
□
□
□
~
□
□
□
□
□
□
□
□
□
~
282
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
24 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.1 Aesthetics
Except as provided in Public Resources Code Section 21099, would the project:
a) Have a substantial adverse effect on a
scenic vista?
b) Substantially damage scenic resources,
including, but not limited to, trees, rock
outcroppings, and historic buildings
within a State Scenic Highway?
c) In non-urbanized areas, substantially
degrade the existing visual character or
quality of public views of the site and its
surroundings? (Public views are those
that are experienced from publicly
accessible vantage points.) If the project
is in an urbanized area, would the
project conflict with applicable zoning
and other regulations governing scenic
quality?
d) Create a new source of substantial light
or glare which would adversely affect
day or nighttime views in the area?
Environmental Evaluation
Setting
The General Plan Conservation/Open Space Element identifies the hillsides, ridgelines, canyons, and view corridors as the primary aesthetic resources in the City. Canyon views and scenic highways are examples of scenic qualities, as defined by the General Plan, benefiting the community. Architectural and landscaping design guidelines complement the natural setting, enhancing the City’s unique visual character.7 Public and private portions of the City bordering the Aliso and Woods Canyons are situated with highly valued viewsheds or scenic overlooks of the canyons. 7 City of Aliso Viejo. 2004. Alisa Viejo General Plan, Conservation/Open Space Element. Website:
https://avcity.org/DocumentCenter/View/394/Conservation--Open-Space-Element-PDF. Accessed April 10, 2026. □
□
□
□
□
□
□
□
□
□
□
□
283
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 25
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx In addition, several City roadways have been designated by the County of Orange Master Plan of Scenic Highways as having scenic qualities worth preserving. These roadways are classified as Viewscape Corridors or Landscape Corridors.8 Additional scenic amenities, such as golf courses, also provide visual relief from the built environment and are important visual amenities and landmarks.

The project site is relatively flat, with the exception of the northern and western portions of the project site which include landscaped slopes ascending toward Glenwood Drive and Aliso Creek Road. The project site is currently developed with a 2-story office building. Surrounding uses include commercial uses and Brookline Park to the west across Aliso Creek Road, and residential uses to the north across Glenwood Drive. As such, the project site’s existing visual character is a combination of urban and suburban uses. Views from the project site are primarily of landscaping and existing development within the immediate area which include Argonaut and parking lots associated with the office buildings to the south and east. Views beyond the project site to the north and west are largely screened by landscaped slopes and changes in elevation. Although distant hillsides are visible from Glenwood Community Park north of the site, they are not visible from the project site due to existing topography.

Existing sources of light and glare include streetlights and lighting on the interiors and exteriors of existing and surrounding buildings as well as vehicle headlights and traffic signals. Landscaping along both sides of Glenwood Drive, Argonaut, and the project site’s western boundary along Aliso Creek Road provides shielding from light and glare on-site.

Would the project:
a) Have a substantial adverse effect on a scenic vista? No impact. The City does not designate any specific scenic vistas; however, it identifies hillsides, ridgelines, canyons, canyon views, and view corridors as the primary aesthetic resources in the City and states that the Aliso and Woods Canyons have viewsheds or scenic overlooks of the canyons.

The project site is in the northern portion of the City, approximately 1.53 miles east of the hillside and canyon area. Because of the distance and intervening development and topography, the project site cannot be seen from the hillsides and canyon areas or from the Aliso Viejo Country Club, nor does the project site have views of these areas.

General Plan Policy COS-4.1 aims to protect scenic landform features such as hillsides, ridgelines, canyons, and view corridors through designation of key areas as open space and use of other land use planning tools. Existing topography, mature landscaping, and surrounding development substantially limit views of these scenic resources from the project site. While intermittent long-range views of surrounding hillsides may be available from portions of Glenwood Drive, Aliso Creek Road, and nearby public open space areas, the project site itself does not provide prominent public viewpoints of scenic hillsides, ridgelines, or canyons. The proposed project would replace an existing office development with residential buildings that would not exceed 36 feet in height and would 8 City of Aliso Viejo. 2004. Aliso Viejo General Plan, Conservation/Open Space Element. Website:
https://avcity.org/DocumentCenter/View/394/Conservation--Open-Space-Element-PDF. Accessed April 10, 2026. 284
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
26 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx remain consistent with the scale of surrounding development similar to the newly approved residential townhomes at 95 Argonaut and the existing townhomes north of Glenwood Drive. As a result, the proposed development would not substantially obstruct or degrade publicly available views of scenic hillsides, ridgelines, canyons, view corridors, or the Aliso Creek landscape corridor from adjacent public roadways or other public viewing areas. Existing topography and intervening development would continue to limit views from the project site while preserving available public views of surrounding scenic resources from Glenwood Drive, Aliso Creek Road, and nearby open space areas. Accordingly, the proposed project would not substantially alter or impede views of surrounding hillsides or the Aliso Creek landscape corridor, would not conflict with General Plan Policy COS-4.1, and would not obstruct publicly available scenic views. Therefore, no impact would occur. b) Substantially damage scenic resources, including, but not limited to, trees, rock outcroppings, and historic buildings within a State Scenic Highway? No impact. The nearest designated State Scenic Highway is SR-91, approximately 18.34 miles north of the project site.9 A portion of SR-1, approximately 4.8 miles southwest of the project site, is identified as being eligible for listing.10 Because of the project site’s distance from that section of SR-1 and from SR-91, as well as the varying topography of the area and intervening development, the project site is not visible from SR-1 or SR-91. Therefore, the proposed project would not damage any scenic resources within a scenic highway and no impact would occur. c) In non-urbanized areas, substantially degrade the existing visual character or quality of public views of the site and its surroundings? (Public views are those that are experienced from publicly accessible vantage points). If the project is in an urbanized area, would the project conflict with applicable zoning and other regulations governing scenic quality?
No impact. The project site is located in an urbanized area and is currently developed with an existing office building and parking lot. As such, this discussion focuses on zoning and other regulations governing scenic quality. The General Plan and Zoning Ordinance define the permitted land uses and the corresponding development standards within the City. The project site currently has a General Plan Land Use Designation of Business Park. The proposed project would require a GPA to amend the land use designation from Business Park to MDR. The proposed project would be consistent with the MDR land use designation’s maximum density of 18 du/acre.

The project site is currently zoned as Business Park-2. The proposed project would require a rezone to amend the zoning of Business Park-2 to RM. The RM zone is intended to provide for the development and preservation of medium density neighborhoods containing detached and attached single-family homes on smaller lots, duplexes, townhomes, apartments, and condominiums (Municipal Code Chapter 15.10). Additionally, the RM zone is intended to provide residential 9 California Department of Transportation (Caltrans). 2026. State Scenic Highways. Website:
https://dot.ca.gov/programs/design/lap-landscape-architecture-and-community-livability/lap-liv-i-scenic-highways.

Accessed April 10, 2026.
10 Ibid.
285
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 27
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx development with a density between 8 and 18 du/acre, with an average density of 12 du/acre.11 In conjunction with the proposed GPA to MDR, pursuant to the RM zoning district, the proposed project would be subject to the RM zoning development standards.

The proposed project would comply with all Municipal Code requirements related to scenic quality, such as Chapter 15.62, Design Standards, which sets out design standards for development within the City and subjects the proposed project to a development review process to ensure the project design is consistent with adopted design guidelines.

The proposed project includes several concessions and waivers pursuant to State Density Bonus Law, including an open space concession, parking standard concession, maximum building height waiver, minimum perimeter setback waiver, and minimum boundary landscaping waiver.

Specifically, as discussed in the Project Description, the proposed project would provide 9 percent common open space compared to the 25 percent otherwise required by the Municipal Code, 140 parking spaces instead of 145 spaces, increase the maximum building height from 35 feet to 36 feet, reduce perimeter setbacks from 20 feet to as little as 5 feet in limited locations, and modify boundary landscaping widths to 5 feet and 20 feet in limited locations.

Despite these modifications, the proposed project would retain substantial open space within preserved slope areas, incorporate new landscaped paseos, private yards, and common amenity areas, and maintain perimeter landscaping exceeding 20 feet along most of the project site boundary.

In addition, the proposed one-foot increase in building height would not alter the visual profile of the surrounding development. The five-space reduction in parking would not affect scenic quality because parking would continue to be accommodated on-site and the reduction would not substantially alter the site's visual appearance. The five-space reduction in parking would not affect or alter scenic quality on-site because parking would continue to be accommodated on-site with attached garages and guest parking. Accordingly, the proposed parking spaces would exceed the parking ratio requirement of 130 total parking spaces pursuant to a concession in accordance with the State Density Bonus Law. The reduced setbacks and landscaping areas would be limited to select portions of the site and would not disrupt the existing visual character of the surrounding urbanized area.

Consequently, the requested concessions and waivers would not substantially degrade scenic quality, obstruct public views, or adversely affect the visual character of the surrounding area.

Furthermore, the retained screening trees along the northern and western boundaries would continue to provide an established vegetated buffer between the project site and surrounding roadways and development. These mature trees currently soften views of the project site, screen portions of the existing office building, and contribute to the landscaped character of the area. Because the perimeter screening trees would be retained, public views from Glenwood Drive, Aliso Creek Road, and adjacent properties would continue to include substantial mature vegetation in the foreground.

Maintaining the existing visual screening features would reduce the visibility of the proposed 11 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element. Website:
https://avcity.org/DocumentCenter/View/391/Land-Use-Element-PDF. Accessed April 10, 2026. 286
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
28 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx residential buildings and help maintain the site's existing visual character despite the proposed reductions in setbacks and landscaping widths in limited areas. Accordingly, the proposed project would not substantially degrade visual character or scenic resources and would remain consistent with the intent of applicable scenic quality policies and design standards.

Furthermore, the proposed project would not conflict with any General Plan policies related to scenic quality, including General Plan Policy COS-4.1 and Policy COS-4.2, which protect scenic landforms such as hillsides, ridgelines, and canyons and encourage high-quality architectural and landscaping design. The proposed project would be located on a previously developed site and would not impact any scenic landforms. As previously mentioned, the proposed project would include a 20-foot setback along its northern and western boundaries, minimizing impacts to scenic resources along Aliso Creek Road, a designated landscape corridor. The existing screening trees along the western and northern perimeters of the project site would be preserved. The proposed project would also be designed with a refined architectural style tailored to reinforce the City’s indoor-outdoor lifestyle, complementing the community’s existing visual character pursuant to General Plan Policy COS-4.2.

The residential buildings would incorporate stucco façades, concrete tile roofs, decorative shutters, articulated building elevations, and complementary earth-tone materials and colors characteristic of existing residential development in Aliso Viejo. The site design also includes landscaped paseos, private yards, amenity areas, and substantial open space along the preserved slope areas, which would enhance visual quality and reinforce the project's integration with the surrounding environment.

The proposed architectural design and materials would be subject to the City’s design review process pursuant to Chapter 15.62 of the Municipal Code, ensuring consistency with adopted design guidelines. As such, the proposed project would not conflict with applicable zoning and other regulations pertaining to scenic quality, and no impacts would occur. d) Create a new source of substantial light or glare which would adversely affect day or nighttime views in the area?
Less than significant impact. The project site is currently developed and located in an urbanized area with existing light sources, which include streetlights and lighting on the interiors and exteriors of existing and surrounding buildings, as well as vehicle headlights and traffic signals. The existing building on-site contains sources of light and glare, including indoor and outdoor lighting, reflective surfaces, and headlights from vehicles in the parking lot.

The proposed project would generate lighting from two primary sources: lighting from the building interiors that would pass through windows and lighting from exterior sources (e.g., street lighting, parking area lighting, building illumination, security lighting, and landscape lighting). The proposed lighting would be typical of residential developments. The proposed development would replace current existing sources of light and glare with new high-quality development and lighting. The proposed project’s lighting would be similar to existing residential development in the area and would not substantially increase sources of light as compared to the existing uses on the project site. 287
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 29
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx No nighttime construction is proposed, and construction activities would be subject to regulations set forth by the City’s Building and Safety Department, which restricts construction activities to between the hours of 7:00 a.m. and 8:00 p.m.12 Therefore, the proposed project would not require construction lighting, except security and safety lighting.

The City’s Building and Safety Department would review any proposed lighting to ensure conformance with the latest version of the California Building Standards Code (CBC), Title 24, as well as the California Green Building Standards Code (CALGreen) (California Code of Regulations [CCR] Title 24, Part 11). The proposed project would comply with all applicable design standards for outdoor lighting stipulated in Municipal Code Section 15.62.070, Outdoor Lighting, including those for the height limitations, lighting intensity and spillover, light fixture design, building illumination, and outdoor lighting for parks and playfields. In accordance with Municipal Code Section 15.62.070, lowheight lighting would be used whenever possible for pedestrian areas and light fixture design would be designed to harmonize with and enhance the character of the proposed project. Although the proposed project would replace the existing office building with new residential buildings that would introduce new light sources, the surrounding area is urban and already illuminated and the proposed lighting conditions would be similar to those currently used on the project site and surrounding the project site. The proposed project would incorporate shielded wall-mounted fixtures, pedestrian-scale lighting, and limited pole-mounted lighting designed to illuminate building entrances, walkways, private streets, and parking areas. Consistent with the Municipal Code, CBC, and CALGreen, lighting would be directed toward on-site activity areas and illumination levels would decrease at the project boundaries, demonstrating that light spill onto adjacent properties would be avoided.

Sunlight or artificial light reflecting from finished surfaces such as window glass or other reflective materials can cause reflected light (glare). Buildings constructed of highly reflective materials from which the sun reflects at a low angle commonly cause adverse glare. The proposed project does not include use of materials known to cause glare such as mirrored/reflective glass. Furthermore, the proposed project’s lighting would be similar to the existing residential uses to the north and would not substantially increase sources of light as compared to the existing uses on the site. Additionally, the topography of the project site, existing screening trees on the northern and western boundaries of the project site, and landscaping within the project site, combined with existing landscaping in the area, would help shield adjacent residential areas from sources of light and glare. Therefore, impacts would be less than significant.

Mitigation Measures
None required.
12 City of Aliso Viejo. 2026. Building & Safety. Website: https://avcity.org/154/Building-Safety. Accessed April 10, 2026. 288
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
30 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.2 Agriculture and Forestry Resources
In determining whether impacts to agricultural resources are significant environmental effects, lead agencies may refer to the California Agricultural Land Evaluation and Site Assessment Model (1997) prepared by the California Dept. of Conservation as an optional model to use in assessing impacts on agriculture and farmland. In determining whether impacts to forest resources, including timberland, are significant environmental effects, lead agencies may refer to information compiled by the California Department of Forestry and Fire Protection regarding the State’s inventory of forest land, including the Forest and Range Assessment Project and the Forest Legacy Assessment project; and forest carbon measurement methodology provided in Forest Protocols adopted by the California Air Resources Board.

Would the project:
a) Convert Prime Farmland, Unique
Farmland, or Farmland of Statewide
Importance (Farmland), as shown on
the maps prepared pursuant to the
Farmland Mapping and Monitoring
Program of the California Resources
Agency, to nonagricultural use?
b) Conflict with existing zoning for
agricultural use, or a Williamson Act
Contract?
c) Conflict with existing zoning for, or
cause rezoning of, forest land (as
defined in Public Resources Code
Section 12220(g)), timberland (as
defined by Public Resources Code
Section 4526), or timberland zoned
Timberland Production (as defined by
Government Code Section 51104(g))?
d) Result in the loss of forest land or
conversion of forest land to non-forest
use?
e) Involve other changes in the existing
environment which, due to their location
or nature, could result in conversion of
□ □ □
□ □ □
□ □ □
□ □ □
□ □ □
289
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 31
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact
Farmland, to nonagricultural use or
conversion of forest land to non-forest
use?
Environmental Evaluation
Setting
The General Plan currently designates the project site as Business Park (Exhibit 3). The proposed project requests a GPA to change the General Plan land use designation from Business Park to MDR. The MDR land use designation is intended for residential uses and does not include agricultural or forestry uses.

The project site is currently zoned Business Park-2 (Exhibit 4). The proposed project requests a rezone to change the zoning designation from Business Park-2 to RM. The RM zoning district is intended to provide for residential uses and does not include agriculture or forestry uses.

The project site is mapped as Urban and Built-up Land by the California Department of Conservation’s Farmland Mapping and Monitoring Program (FMMP).13 Urban and Built-up Land is a nonagricultural land use designation.14 The project site was historically undeveloped until 1963, when a single road traversed the site, and by 1989, an office building was developed on the project site.15 Would the project:
a) Convert Prime Farmland, Unique Farmland, or Farmland of Statewide Importance (Farmland), as shown on the maps prepared pursuant to the Farmland Mapping and Monitoring Program of the California Resources Agency, to nonagricultural use? No impact. The project site is mapped as “Urban and Built-up Land” by the California Department of Conservation’s FMMP, which is a nonagricultural land use designation. There is no Prime Farmland, Unique Farmland, or Farmland of Statewide Importance on or near the project site. The nearest designated farmland is Prime Farmland and Unique Farmland located 2.70 miles north of the project 13 Department of Conservation. 2026. California Important Farmland Finder. Website:
https://maps.conservation.ca.gov/DLRP/CIFF/. Accessed April 10, 2026. 14 Ibid.
15 Stantec. 2025. Phase I Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. July 14. 290
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
32 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx site.16 Additionally, the General Plan does not designate the site as agricultural or forest land, and the project site is not in active agricultural use. These conditions preclude the possibility of conversion of farmland to nonagricultural use. No impact would occur. b) Conflict with existing zoning for agricultural use, or a Williamson Act Contract? No impact. The proposed project requests a rezone to change the zoning designation from Business Park-2 to RM and is therefore not zoned for agricultural uses. The project site is currently developed with an office building and parking lot and does not support agricultural land use activities and, therefore, is not eligible for a Williamson Act Contract. This condition precludes the possibility of conflicts with agricultural zoning or Williamson Act Contracts. No impact would occur. c) Conflict with existing zoning for, or cause rezoning of, forest land (as defined in Public Resources Code Section 12220(g)), timberland (as defined by Public Resources Code Section 4526), or timberland zoned Timberland Production (as defined by Government Code Section 51104(g))?
No impact. The proposed project requests a rezone to change the zoning designation from Business Park-2 to RM; both are non-forest zoning districts. This condition precludes the possibility of conflicts with forest zoning. No impact would occur.
d) Result in the loss of forest land or conversion of forest land to non-forest use? No impact. The project site is mapped as “Urban and Built-up Land” by the California Department of Conservation’s FMMP. The project site is currently developed with an office building and parking lot and does not contain forestland, timberland, or timberland zoned Timberland Production as defined by Public Resources Code Section 51104(g). This condition precludes the possibility of the conversion of forest land to non-forest use. No impact would occur. e) Involve other changes in the existing environment which, due to their location or nature, could result in conversion of Farmland to nonagricultural use or conversion of forest land to non-forest use?
No impact. The project site and surrounding area are mapped as “Urban and Built-up Land” by the California Department of Conservation’s FMMP. The project site is not located on or near land used for farmland or agriculture. This condition precludes the possibility of the proposed project creating pressures to convert farmland to nonagricultural use or forest land to non-forest use. No impact would occur.

Mitigation Measures
None required.
16 Department of Conservation. 2026. California Important Farmland Finder. Website:
https://maps.conservation.ca.gov/DLRP/CIFF/. Accessed April 10, 2026. 291
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 33
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.3 Air Quality
Where available, the significance criteria established by the applicable air quality management district or air pollution control district may be relied upon to make the following determinations.

Would the project:
a) Conflict with or obstruct implementation
of the applicable air quality plan?
b) Result in a cumulatively considerable
net increase of any criteria pollutant for
which the project region is
nonattainment under an applicable
federal or State ambient air quality
standard?
c) Expose sensitive receptors to
substantial pollutant concentrations?
d) Result in other emissions (such as
those leading to odors or) adversely
affecting a substantial number of
people?
Environmental Evaluation
Where available, the significance criteria established by the applicable air quality management district or air pollution control district may be relied upon to make the following determinations.

Setting
The proposed project site is located in the City of Aliso Viejo, in Orange County, which is within the South Coast Air Basin (SoCAB). The SoCAB includes all of Orange County, Los Angeles County (except for the Antelope Valley), the non-desert portion of western San Bernardino County, and the western and Coachella Valley portions of Riverside County. The San Gabriel, San Bernardino, and San Jacinto Mountains bound the SoCAB on the north and east, while the Pacific Ocean lies to the □
□
□
□
□
□
□
□
□
□
□
□
292
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
34 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx west of the SoCAB. The southern limit of the SoCAB is the San Diego County line. The SoCAB is under the jurisdiction of South Coast Air Quality Management District (South Coast AQMD).17 The air pollutants for which national and State standards have been promulgated and that are most relevant to air quality planning and regulation in the SoCAB include ozone, nitrogen oxides (NOX), carbon monoxide (CO), particulate matter, including dust, 10 microns or less in diameter (PM10), and particulate matter, including dust, 2.5 microns or less in diameter (PM2.5). In addition, toxic air contaminants (TACs) are of concern in the SoCAB. Each of these pollutants is briefly described below. Other pollutants that are regulated but not considered an issue in the project area are sulfur dioxide (SO2), vinyl chloride, sulfates, hydrogen sulfide, and lead; the proposed project would not emit substantial quantities of those pollutants, so they are not discussed further in this section.

Construction and operation of the proposed project would be subject to applicable South Coast AQMD rules and requirements. The South Coast AQMD Air Quality Significance Thresholds18 and Localized Significance Thresholds19 were developed to assist local jurisdictions and lead agencies in complying with the requirements of CEQA regarding potentially adverse impacts to air quality.

Would the project:
a) Conflict with or obstruct implementation of the applicable air quality plan? Less than significant impact. A potentially significant impact would occur if the proposed project would conflict with or obstruct implementation of the applicable air quality plan. The South Coast AQMD is responsible for preparing air quality attainment plans to be transmitted to the California Air Resources Board (CARB) and the United States Environmental Protection Agency (EPA) for incorporation into the State Implementation Plan (SIP). South Coast AQMD has designated this area as extreme nonattainment for ozone and serious nonattainment for PM2.5. 20 To evaluate whether a project conflicts with or obstructs implementation of the applicable air quality plan (2022 Air Quality Management Plan [AQMP] for SoCAB), the South Coast AQMD CEQA Air Quality Handbook states that there are two key indicators. These indicators are identified by the criteria discussed below.

Indicator: Whether the proposed project will not result in an increase in the frequency or severity of existing air quality violations, or cause or contribute to new violations, or delay timely attainment of air quality standards or the interim emission reductions specified in the AQMP. 17 South Coast Air Quality Management District (South Coast AQMD). 2022. Air Quality Management Plan. Website:
http://www.aqmd.gov/home/air-quality/clean-air-plans/air-quality-mgt-plan. Accessed May 11, 2026. 18 South Coast Air Quality Management District (South Coast AQMD). 2023. Air Quality Significance Thresholds. March.

Website: https://www.aqmd.gov/docs/default-source/ceqa/handbook/south-coast-aqmd-air-quality-significancethresholds.pdf?sfvrsn=f7601d61_25. Accessed May 12, 2026. 19 South Coast Air Quality Management District (South Coast AQMD). Localized Significance Thresholds. Website:
https://www.aqmd.gov/home/rules-compliance/ceqa/air-quality-analysis-handbook/localized-significance-thresholds.

Accessed May 12, 2026.
20 South Coast Air Quality Management District (South Coast AQMD). 2022. Air Quality Management Plan. Website:
http://www.aqmd.gov/home/air-quality/clean-air-plans/air-quality-mgt-plan. Accessed May 12, 2026. 293
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 35
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx If a project’s emissions do not exceed the South Coast AQMD regional thresholds for volatile organic compounds (VOC), NOX, CO, sulfur oxides (SOX), PM10, or PM2.5, it follows that the project’s emissions would not exceed the allowable limit for each project in order for the region to attain and maintain ambient air quality standards, which is the primary goal of air quality plans. As shown in Impact 2.3(b), the proposed project would not exceed the South Coast AQMD’s regional thresholds of significance during either construction or operation. Therefore, the proposed project would be consistent with the AQMP under this criterion.

Indicator: According to Chapter 12 of the South Coast AQMD CEQA Air Quality Handbook, the purpose of the General Plan consistency findings is to determine whether a proposed project is inconsistent with the growth assumptions incorporated into the air quality plan and, thus, whether it would interfere with the region’s ability to comply with federal and California air quality standards.

The development of emission inventories used in AQMPs to demonstrate compliance with ambient air quality standards is based on regional growth forecasts developed by the Southern California Association of Governments (SCAG). These forecasts include population, employment, and vehicle activity projections and form the basis for estimating future emissions within the air basin. While SCAG forecasts are informed by local land use plans, including general plans, they represent a regionally integrated projection of growth rather than a direct translation of individual jurisdiction land use designations. The General Plan and Zoning Ordinance define the permitted land uses and the corresponding development standards within the City. The project applicant requests a GPA to change the General Plan land use designation from Business Park-2 to MDR and a rezone to change the zoning designation to RM. As such, the proposed project would differ from the land use assumptions associated with the existing General Plan and may not precisely match the inputs used in preparation of the 2022 AQMP.

However, AQMP consistency is evaluated based on whether a project’s population growth and associated vehicle miles traveled (VMT) are within the regional growth projections established by SCAG. As described in Section 2.14, Population and Housing, the City’s population remains below SCAG projections, and the proposed project would incrementally contribute to planned growth without exceeding those forecasts. Furthermore, as explained in Section 2.17, Transportation, based on the City’s VMT screening types and the net reduction of daily vehicle trips, the proposed project meets the Project Type screening criterion and is considered to have a less than significant VMT impact.

Although the proposed project would increase the residential population on the site, the existing office use also contributes to regional growth forecasts through employment generation and associated travel demand. Therefore, the proposed project reflects a change in land use rather than growth substantially exceeding that anticipated in SCAG's regional planning projections.

Therefore, although the proposed project represents a land use change at the local level, it would not result in population growth or VMT substantially greater than that anticipated in regional projections.

Because the AQMP relies on SCAG growth forecasts, and the proposed project would remain within those forecasts, the project would not interfere with the region’s ability to attain and maintain federal and State ambient air quality standards.
294
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
36 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Therefore, the proposed project would not conflict with the applicable air quality plan. Impacts would be less than significant.
b) Result in a cumulatively considerable net increase of any criteria pollutant for which the project region is nonattainment under an applicable federal or State ambient air quality standard?
Less than significant impact. This impact is related to the cumulative effect of a project’s criteria pollutant emissions. By its nature, air pollution is largely a cumulative impact resulting from emissions generated over a large geographic region. The nonattainment status of regional pollutants results from past and present development within the SoCAB, and this regional impact is a cumulative impact. Therefore, new development projects (such as the proposed project) within the SoCAB would contribute to this impact only on a cumulative basis. No single project would be sufficient in size, by itself, to result in nonattainment of regional air quality standards. Instead, a project’s emissions may be individually limited but cumulatively considerable when evaluated in combination with past, present, and future development projects.

Potential regional impacts could result in exceedances of State or federal standards for NOX, PM10, PM2.5, or CO. NOX emissions are of concern because of potential health impacts from exposure to NOX emissions during both construction and operation and as a precursor in the formation of airborne ozone. PM10 and PM2.5 are of concern during construction because of the potential to emit exhaust emissions from the operation of off-road construction equipment and fugitive dust during grounddisturbing activities (construction fugitive dust). CO emissions are of concern during project operation because operational CO hotspots are related to increases in on-road vehicle congestion and resulting health effects.

VOC emissions are also important because of their participation in the formation of ground level ozone. Ozone is a respiratory irritant and an oxidant that increases susceptibility to respiratory infections and can cause substantial damage to vegetation and other materials. Elevated ozone concentrations result in reduced lung function, particularly during vigorous physical activity. This health problem is particularly acute in sensitive receptors, such as the sick, elderly, and young children.

The cumulative analysis focuses on whether a specific project would result in cumulatively considerable emissions. According to CEQA Guidelines Section 15064(h)(4), the existence of significant cumulative impacts caused by other projects alone does not constitute substantial evidence that a project’s incremental effects would be cumulatively considerable. Rather, the determination of cumulative air quality impacts for construction and operational emissions is based on whether the proposed project would result in regional emissions that exceed the South Coast AQMD regional thresholds of significance for construction and operations on a project level. Projects that generate emissions below the South Coast AQMD significance thresholds would be considered consistent with regional air quality planning efforts and would not generate cumulatively considerable emissions. The proposed project’s regional construction and operational emissions are evaluated separately below. Construction and operational emissions from the proposed project were estimated 295
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 37
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx using the California Emissions Estimator Model (CalEEMod) Version 2022.1. The complete CalEEMod output files are included as part of Appendix A.

Construction Emissions
Construction emissions are described as “short-term” or temporary in duration; however, they have the potential to represent a significant impact with respect to air quality. Construction of the proposed project would result in the temporary generation of VOC, NOX, CO, SOX, PM10, and PM2.5 emissions from construction activities such as demolition, site preparation, grading, building construction (home construction), architectural coating, and paving. Fugitive dust emissions are primarily associated with ground disturbance and grading activities and vary as a function of soil silt content, soil moisture, wind speed, acreage of disturbance area, and miles traveled by construction vehicles on-site and offsite. Construction-related NOX emissions are primarily generated by exhaust emissions from heavyduty construction equipment, material and haul trucks, and construction worker vehicles. VOC emissions are mainly generated by exhaust emissions from construction vehicles, off-gas emissions associated with architectural coatings, and asphalt paving.

The proposed project would be required to comply with all applicable South Coast AQMD rules and regulations intended to minimize emissions during construction activities. These requirements include measures to reduce fugitive dust emissions and limit the use of high–volatile VOC materials. The following South Coast AQMD rules are applicable to the proposed project:

South Coast AQMD Rule 403
South Coast AQMD Rule 403 requires the implementation of best available dust control measures during activities capable of generating fugitive dust. The proposed project must follow the standard South Coast AQMD rules and requirements with regard to fugitive dust control, which include, but are not limited to the following:

1. All active construction areas shall be watered two times daily.

2. Speed on unpaved roads shall be reduced to less than 15 miles per hour (mph).

3. Any visible dirt deposition on any public roadway shall be swept or washed at the site access points within 30 minutes.

4. Any on-site stockpiles of debris, dirt, or other dusty material shall be covered or watered twice daily.

5. All operations on any unpaved surface shall be suspended if winds exceed 15 mph.

6. Access points shall be washed or swept daily.

7. Construction sites shall be sandbagged for erosion control.

8. Apply nontoxic chemical soil stabilizers according to manufacturers’ specifications to all inactive construction areas (previously graded areas inactive for 10 days or more). 296
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
38 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx

9. Cover all trucks hauling dirt, sand, soil, or other loose materials, and maintain at least 2 feet of freeboard space in accordance with the requirements of California Vehicle Code (CVC) Section 23114.

10. Pave or gravel construction access roads at least 100 feet onto the site from the main road and use gravel aprons at truck exits.

11. Replace the ground cover of disturbed areas as quickly as possible.

South Coast AQMD Rule 1113
All interior and exterior architectural coatings used on-site during project construction must meet or exceed the VOC content limits established by South Coast AQMD Rule 1113. The project sponsor shall include in any construction contracts and/or subcontracts a requirement that all interior and exterior architectural coatings used in project construction meet the VOC content limits established by South Coast AQMD Rule 1113.

For the purpose of this analysis, construction of the proposed project was estimated to begin on March 2027, and would be completed by November 2028, and was modeled based on an applicantprovided preliminary schedule; see Appendix A. Note that construction emissions would likely decrease if the construction schedule were deferred to later years because of improvements in technology and more stringent regulatory requirements. The duration of construction activity and associated equipment represents a reasonable approximation of the expected construction fleet as required by the CEQA Guidelines. The calculations of pollutant emissions from the construction equipment account for the type of equipment, horsepower and load factors of the equipment, and the duration of equipment use. Table 1 presents the proposed project’s maximum daily construction emissions during the entire construction duration using the worst-case summer or winter daily construction-related criteria pollutant emissions for each phase of construction.21 The PM10 and PM2.5 emissions reflect the combined exhaust and fugitive dust emissions after implementation of best available dust control measures outlined in South Coast AQMD Rule 403. Complete CalEEMod output files are included as part of Appendix A.

Table 1: Unmitigated Construction—Maximum Daily Regional Emissions by Year Construction Year
Regional Pollutant Emissions (pounds per day)
VOC NOX CO SOX PM10 PM2.5
Maximum Daily from Project
Construction (2027)

3.1 28.2 29.2 0.05 6.6 3.8
21 At the time the air quality modeling was prepared, the proposed project was anticipated to achieve a balanced cut-and-fill condition and, therefore, no off-site soil export was assumed. Subsequent refinement of the grading plan identified the need to export approximately 473 cubic yards of soil. This volume represents a relatively small amount of material and would generate only a limited number of additional haul truck trips per day over the course of the grading period. The incremental emissions associated with these trips would constitute a negligible fraction of the overall construction emissions evaluated for the project and would not materially alter the results or conclusions of the air quality analysis.

Construction emissions would remain below applicable significance thresholds. 297
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 39
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Construction Year
Regional Pollutant Emissions (pounds per day)
VOC NOX CO SOX PM10 PM2.5
Maximum Daily from Project
Construction (2028)

21.9 9.2 15 0.02 0.9 0.4
Maximum Daily Construction Emissions
Maximum Daily Emissions 21.9 28.2 29.2 0.05 6.6 3.8
South Coast AQMD
Significance Threshold
75 100 550 150 150 55
Exceed Threshold? No No No No No No
Notes:

CO = carbon monoxide
NOX = nitrogen oxides
PM10 = particulate matter less than 10 microns in diameter PM2.5 = particulate matter less than 2.5 microns in diameter South Coast AQMD = South Coast Air Quality Management District SOX = sulfur oxides
VOC = volatile organic compound
South Coast AQMD Rule 403 dust control measures available within CalEEMod have been applied in the emissions modeling.

Source of Emissions: Appendix A.

As shown above in Table 1, the proposed project’s construction emissions would not exceed the applicable significance threshold for any of the pollutants. Therefore, the proposed project would have a less than significant impact related to regional air quality during project construction.

Operational Emissions
Long-term operational emissions would be generated, resulting from daily operations at the proposed townhomes. Operational emissions for residential land use development projects are typically distinguished as mobile-, area-, and energy-source emissions. Mobile source emissions are those associated with automobiles that would travel to and from the project site. Trip rates used to estimate mobile source emissions that would be generated by the proposed project were consistent with the daily trips presented in the project-specific Trip Generation and VMT Assessment Memorandum (Appendix I). The proposed project would replace the existing office uses on-site, but for conservative purposes, the analysis does not account for the removal of the existing emissions, such as car trips, that would be replaced by the proposed project. Area-source emissions are those associated with landscape maintenance activities and periodic architectural coatings. The proposed project would be all electric and would not have any natural gas infrastructure. Therefore, there are no direct emissions related to building energy use for space or water heating. Table 2 presents the proposed project’s estimated maximum daily operational emissions.
298
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
40 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Table 2: Maximum Daily Operational Regional Pollutants
Operational Activity
Regional Pollutant Emissions (pounds per day)1

VOC NOX CO SOX
PM10
(Total)
PM2.5
(Total)
Mobile (Automobiles) 1.0 0.8 8.4 <0.01 2.2 0.6
Energy 0.0 0.0 0.0 0.0 0.0 0.0
Area 2.5 0.03 3.3 <0.01 <0.01 <0.01
Overall Maximum Daily1 3.5 0.8 11.7 <0.01 2.2 0.6
South Coast AQMD
Significance Threshold
55 55 550 150 150 55
Exceed Threshold? No No No No No No
Notes:

CO = carbon monoxide
NOX = nitrogen oxides
PM10 = particulate matter less than 10 microns in diameter PM2.5 = particulate matter less than 2.5 microns in diameter South Coast AQMD = South Coast Air Quality Management District SOX = sulfur oxides
VOC = volatile organic compounds
1 Emissions shown represent the maximum total daily operational emissions for summer or winter season.

Source of Table: Appendix A.

As shown in Table 2, the proposed project’s regional daily operational emissions would not exceed any of the South Coast AQMD thresholds of significance. Therefore, the proposed project would have a less than significant impact related to regional air quality during project operation. c) Expose sensitive receptors to substantial pollutant concentrations? Less than significant impact. This impact evaluates the potential for the proposed project’s construction and operational emissions to expose sensitive receptors to substantial pollutant concentrations. Sensitive receptors are defined as those individuals who are sensitive to air pollution, including children, the elderly, and persons with pre-existing respiratory or cardiovascular illness. For purposes of CEQA, the South Coast AQMD considers a sensitive receptor to be a location where a sensitive individual could remain for 24 hours, such as residences, hospitals, or convalescent facilities. Commercial and industrial facilities are not included in the definition because employees do not typically remain on-site for 24 hours.

Localized Significance Threshold Analysis—Criteria Pollutants The localized construction and operational analyses use thresholds (i.e., localized significance thresholds [LSTs]) that represent maximum emissions for a project that would not cause or contribute to an exceedance of the most stringent applicable federal or State ambient air quality standard. If the 299
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 41
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx proposed project’s construction or operational emissions are under those thresholds, it follows that the proposed project would not cause or contribute to an exceedance of the standard and would not expose sensitive receptors to substantial pollutant concentrations.

Friant Ranch Case and Project Health Impacts
In the Fifth District Court of Appeal case Sierra Club v. County of Fresno (Friant Ranch, L.P.) (also referred to as Friant Ranch) the Court found the project EIR deficient because it did not identify specific health-related effects resulting from the estimated amount of pollutants generated by the project. The ruling stated that the EIR should give a “sense of the nature and magnitude of the ‘health and safety problems’ caused by a project’s air pollution. The EIR should translate the emission numbers into adverse impacts or to understand why such translation is not possible at this time (and what limited translation is, in fact, possible).”
The California Supreme Court held that when an EIR concluded that a project would have significant impacts to air quality, an EIR should “make a reasonable effort to substantively connect a project’s air quality impacts to likely health consequences.” In order to determine compliance with this case, the Court developed a multi-part test that includes the following:

1. The air quality discussion shall describe the specific health risks created from each criteria pollutant, including diesel particulate matter (DPM).

This air quality analysis details the specific health risks created from each criteria pollutant above under Section 2.3, Air Quality, Environmental Setting, Air Pollutants. As such, this analysis meets the Part 1 of the Friant Ranch case test.

2. The analysis shall identify the magnitude of the health risks created by the project. On page 24 of the Ruling, it is stated that “[t]he Court of Appeal identified several ways in which the EIR could have framed the analysis so as to adequately inform the public and decision-makers of possible adverse health effects.”
The Friant Ranch case found that an EIR's air quality analysis must meaningfully connect the identified air quality impacts to the human health consequences of those impacts or meaningfully explain why that analysis cannot be provided. As noted in the brief of Amicus Curiae by the South Coast AQMD Friant Ranch (Brief), 22 South Coast AQMD has air quality modeling and health impact evaluation capability among the most sophisticated of any of the air districts in the State, and thus it is uniquely situated to express an opinion on how lead agencies should correlate air quality impacts with specific health outcomes. The South Coast AQMD discusses that it may be infeasible to quantify health risks caused by projects similar to the proposed project due to various factors. The Brief states that it may not be feasible to perform a health risk assessment for airborne toxics that will be emitted by a generic industrial building that was built on "speculation" (i.e., without knowing the future 22 South Coast Air Quality Management District (South Coast AQMD). 2015. Application of the South Coast Air Quality Management District for Leave to File Brief of Amicus Curiae in Support of Neither Party and [Proposed] Brief of Amicus Curiae. Website: https://www.courts.ca.gov/documents/9-s219783-ac-south-coast-air-quality-mgt-dist-041315.pdf.

Accessed March 2, 2025.
300
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
42 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx tenant(s)). Even where a health risk assessment can be prepared, the resulting maximum health risk value is only a calculation of risk; it does not necessarily mean anyone will contract cancer as a result of the project. Similarly, South Coast AQMD staff does not currently know of a way to accurately quantify ozone-related health impacts caused by NOX or VOC emissions from relatively small projects due to photochemistry and regional model limitations. The Brief concludes, with respect to the Friant Ranch EIR, that although it may have been technically possible to plug the data into a methodology, the results would not have been reliable or meaningful.

On the other hand, for extremely large regional projects (unlike the proposed project), the South Coast AQMD states that it has been able to correlate potential health outcomes for very large emissions sources—as part of their rulemaking activity, specifically, 6,620 pounds per day of NOX and 89,180 pounds per day of VOC were expected to result in approximately 20 premature deaths per year and 89,947 school absences due to ozone. As shown above in Table 1, project-related construction activities would generate a maximum of 21.9 pounds per day of VOC and 28.2 pounds per day of NOX; and, as shown above in Table 2, operation of the proposed project is estimated to generate 3.5 pounds per day of VOC and 0.8 pounds per day NOX. The proposed project would not generate emissions anywhere near levels that would reach 6,620 pounds per day of NOX or 89,190 pounds per day of VOC emissions. Therefore, the proposed project’s emissions are not sufficiently high enough to use a regional modeling program to correlate health effects on a basin-wide level.

Notwithstanding, this analysis does evaluate the proposed project’s localized impact to air quality for emissions of NOX, CO, PM10, and PM2.5 by comparing the proposed project’s on-site emissions to the South Coast AQMD’s applicable LST thresholds. LSTs are derived to ensure that short-term or localized emissions do not cause or contribute to exceedances of ambient air quality standards, which are established to protect public health, including sensitive populations such as children and the elderly. As such, compliance with LSTs serves as a screening tool to evaluate whether a project’s localized criteria pollutant concentrations could affect nearby sensitive receptors. As evaluated in this analysis provided below, the proposed project would not result in emissions that exceeded the South Coast AQMD’s LSTs during either the construction or operational period. Therefore, the proposed project would not be expected to exceed the most stringent applicable federal or State ambient air quality standards for emissions of NOX, CO, PM10, or PM2.5.

Localized Construction Analysis
The LST Methodology only applies to on-site emissions and states that “off-site mobile emissions from the project should not be included in the emissions compared to LSTs.” However, for conservative analysis purposes, the analysis includes both off-site and on-site emissions.

Utilizing the earthmoving activity acreages and phase durations from CalEEMod (Section 5.6.1), the number of acres disturbed per day was 1.5 for site preparation and 1.0 for grading. As specified in South Coast AQMD’s guidance, Fact Sheet for Applying CalEEMod to Localized Significance Thresholds, the appropriate thresholds were selected based on the maximum number of acres 301
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 43
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx disturbed in a day. To ensure a conservative analysis, the proposed project emissions have been compared to the 1 acre per day LST.23
Table 3 presents the proposed project’s maximum daily on-site emissions compared with the applicable LSTs. The LSTs for the project site were obtained from the South Coast AQMD LST methodology for a 1-acre project located in Source Receptor Area 20 (Central Coastal Orange County). The nearest sensitive receptors are located approximately 265 feet (80 meters) from the project site. Because this distance falls between the LST lookup table distances of 50 and 100 meters, the 50-meter thresholds were conservatively applied.

As noted in Table 3, emission estimates account for implementation of South Coast AQMD Rule 403 (incorporated into the proposed project through SC AIR-1).

Table 3: Construction Localized Significance Screening Analysis Activity
Emissions (pounds per day)
NOX CO PM10 PM2.5
Maximum Daily from Project Construction (2027) 28.2 29.2 6.6 3.8 Maximum Daily from Project Construction (2028) 9.1 15 0.9 0.4 Maximum Daily Construction Emissions 28.2 29.2 6.6 3.8
Construction Localized Significance Threshold
(Source Receptor Area 20, 1 acre disturbed, 50 meters)
93 738 13 5
Exceed Screening Threshold? No No No No
Notes:

CO = carbon monoxide
NOX = nitrogen oxides
PM10 = particulate matter less than 10 microns in diameter PM2.5 = particulate matter less than 2.5 microns in diameter South Coast AQMD = South Coast Air Quality Management District South Coast AQMD Rule 403 dust control measures available within CalEEMod have been applied in the emissions modeling.

Source of emissions: Appendix A.

Source of thresholds: South Coast Air Quality Management District (South Coast AQMD). Mass Rate Localized Significance Threshold (LST) Lookup Table for Source Receptor Area 20, 1 acre disturbed, within nearest sensitive receptor at a distance of 50 meters from the project site.

As shown in Table 3, the proposed project’s maximum daily emissions would not exceed any applicable South Coast AQMD LSTs for sensitive receptors. In addition, consistent with South Coast AQMD's LST Methodology, commercial receptors are also evaluated for NO₂ and CO because these 23 Because South Coast AQMD localized significance threshold (LSTs) are derived using dispersion modeling that distributes emissions across the assumed project footprint, a smaller site size results in higher concentrations at nearby receptors for the same emission rate. As a result, lower allowable emission thresholds are established for smaller sites.

T 1
302
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
44 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx pollutants are based on shorter averaging periods (one to eight hours) during which workers may reasonably be present on-site. The nearest commercial receptors are located immediately east of the project boundary. Because the distance to these receptors is less than 25 meters, the South Coast AQMD LST Methodology recommends application of the 25-meter LST values. Accordingly, predicted NOx and CO emissions were compared to the applicable 25-meter LSTs for the nearest commercial receptor. The applicable thresholds are 92 pounds per day for NOx and 647 pounds per day for CO.

As shown in Table 3, above, the proposed project's maximum daily emissions are substantially below these thresholds, demonstrating that the proposed project would not cause or contribute to an exceedance of the applicable ambient air quality standards and would result in a less-than-significant localized air quality impact at nearby commercial receptors as well as residential receptors.

Therefore, localized construction impacts related to these air pollutants would be less than significant.

Localized Operational Analysis
Similar to the construction LST analysis above, the applicable operational LSTs were obtained for a project located in Source Receptor Area 20 with the nearest sensitive receptor being at a distance of 50 meters. South Coast AQMD provides LST thresholds for projects equal to 1 acre, 2 acres, or 5 acres in size. For the project site of 4.4 acres, the lower, more conservative threshold for a 2-acre site is used.

Table 4 presents the proposed project’s maximum daily emissions compared with the appropriate LSTs.

Table 4: Operational Localized Screening Significance Analysis Emissions Source
Pounds per Day
NOX CO PM10 PM2.5
Maximum Daily On-site Operational Emissions 0.8 11.7 2.3 0.6 Localized Significance Thresholds (Source
Receptor Area 20, 2-acre site, 50 meters)
128 1,089 6 2
Exceeds Screening Threshold? No No No No
Notes:

CO = carbon monoxide
NOX = nitrogen oxides
PM10 = particulate matter less than 10 microns in diameter PM2.5 = particulate matter less than 2.5 microns in diameter Source of Emissions: Appendix A.

Source of thresholds: South Coast AQMD Mass Rate Lookup Tables for a 2-acre site in Source Receptor Area 20 for sensitive receptors located within 50 meters of the project site.

As shown in Table 4, the proposed project’s maximum daily operational emissions would not exceed any applicable South Coast AQMD LSTs.
1 303
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 45
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx In addition, commercial receptors are also evaluated for NO₂ and CO. The nearest commercial receptors are located immediately adjacent to the project boundary; therefore, consistent with the South Coast AQMD LST Methodology, the 25-meter operational LSTs were applied. The applicable operational thresholds are 131 pounds per day for NOx and 962 pounds per day for CO. As shown in Table 4, above, the proposed project's operational emissions are substantially below these thresholds and would not result in a significant localized air quality impact.

Therefore, the proposed project’s operational activities would not cause or contribute substantially to an existing or future ambient air quality standard violation. Accordingly, the proposed project’s operational criteria air pollutant and ozone precursor concentrations would not expose sensitive receptors to substantial pollutant concentrations. The impact would be less than significant.

Construction-related Diesel Particulate Matter
Project construction would generate DPM emissions from the use of off-road diesel equipment. The extent to which nearby receptors are exposed, determined by pollutant concentration and duration of exposure, is the primary factor used to evaluate health risks associated with TACs. Health risks from diesel exhaust are primarily associated with long-term exposure, particularly with respect to increased cancer risk.

The use of diesel-powered construction equipment would be temporary and episodic, and emissions would be short-term in duration and variable in location as construction activities progress across the site. As a result, potential exposure to DPM would be limited in both duration and intensity, and emissions would disperse rapidly with distance from the source.

Health risk assessment methodologies developed by the California Office of Environmental Health Hazard Assessment (OEHHA) are typically used to evaluate longer-term exposure scenarios. In this case, construction-related DPM emissions would be temporary, intermittent, and geographically variable, and therefore are not well-represented by standard long-term exposure assumptions.

Accordingly, construction-related TAC impacts are evaluated qualitatively.

The nearest sensitive receptors are located approximately 265 feet north of the project site, which provides further attenuation of pollutant concentrations due to dispersion over distance. Construction activities would also be subject to California regulations limiting the idling of heavy-duty diesel equipment to no more than 5 minutes, which would further reduce short-term emissions and associated exposure.

Given the temporary and mobile nature of construction emissions, the limited duration of exposure, regulatory controls on diesel equipment, and the distance to nearby sensitive receptors, constructionrelated DPM emissions would not expose sensitive receptors to substantial levels of TAC. Therefore, impacts would be less than significant.

Carbon Monoxide Hotspot Analysis
A CO hotspot represents a condition wherein high concentrations of CO may be produced by motor vehicles accessing a congested traffic intersection under heavy traffic volume conditions. It has long 304
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
46 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx been recognized that CO exceedances are caused by vehicular emissions, primarily when idling at intersections. Accordingly, vehicle emissions standards have become increasingly more stringent to help remedy this impact. The CO hotspot analysis contained in the South Coast AQMD 1992 CO Plan is used to determine potential CO hotspot impacts from the proposed project, because by using the 1992 CO Plan as a worst-case scenario, the proposed project can measure CO impacts against intersections that experienced significantly more vehicle traffic than those adjacent to the proposed project. The 1992 CO Plan is used as a worst-case scenario because it included a CO hot spot analysis for four busy intersections in Los Angeles at the peak morning and afternoon time periods.

The intersections evaluated included Long Beach Boulevard and Imperial Highway (Lynwood); Wilshire Boulevard and Veteran Avenue (Westwood); Sunset Boulevard and Highland Avenue (Hollywood); and La Cienega Boulevard and Century Boulevard (Inglewood). The busiest intersection evaluated was that at Wilshire Boulevard and Veteran Avenue, which has a daily traffic volume of approximately 100,000 vehicles per day. Subsequently, the CO Plan determined that no CO hotspot would occur even with 100,000 vehicles per day at this one intersection.

According to the transportation analysis prepared by Urban Crossroads, the proposed project would only generate 23 AM peak-hour trips and 31 PM peak-hour trips. For conservative analysis purposes, this analysis does not take credit for the removal of the office use and associated trips. Therefore, the proposed project would not result in traffic volumes exceeding 100,000 vehicles per day at any of the intersections evaluated near the project site. As a result, none of the intersections near the proposed project site would have peak-hour traffic volumes exceeding those at the intersections analyzed in the 1992 CO Plan. Additionally, the adjacent roadways are not located in an area where vertical or horizontal atmospheric mixing is substantially limited, such as a tunnel or overpass. Furthermore, there are no factors unique to the local meteorology to conclude that this intersection would yield higher CO concentrations if modeled in detail. Therefore, the operational CO impact would be less than significant.

In conclusion, the proposed project would not expose sensitive receptors to substantial pollutant concentrations either during construction or operation. Impacts would be less than significant. d) Result in other emissions (such as those leading to odors) adversely affecting a substantial number of people?
Less than significant impact. Odors can cause a variety of responses. The impact of an odor is dependent on interacting factors such as frequency (how often), intensity (strength), duration (in time), offensiveness (unpleasantness), location, and sensory perception. While offensive odors rarely cause any physical harm, they still can be very unpleasant, leading to considerable distress and often generating citizen complaints to local governments and regulatory agencies.

The South Coast AQMD does not provide a suggested screening distance for odor-generating land uses and operations. However, the San Joaquin Valley Air Pollution Control District (Valley Air District) does have a screening distance for odor sources. These screening distances by type of odor generator are listed below in Table 5.
305
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 47
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Table 5: Screening Levels for Potential Odor Sources
Odor Generator Screening Distance
Wastewater Treatment Facilities 2 miles
Sanitary Landfill 1 mile
Transfer Station 1 mile
Composting Facility 1 mile
Petroleum Refinery 2 miles
Asphalt Batch Plant 1 mile
Chemical Manufacturing 1 mile
Fiberglass Manufacturing 1 mile
Painting/Coating Operations (e.g., auto body shop) 1 mile Food Processing Facility 1 mile
Feed Lot/Dairy 1 mile
Rendering Plant 1 mile
Source: San Joaquin Valley Air Pollution Control District (Valley Air District). 2015. Guidance for Assessing and Mitigating Air Quality Impacts (GAMAQI). March 19. Website:
https://valleyair.org/transportation/GAMAQI.pdf. Accessed May 12, 2026.

Construction-related Odors
Potential sources that may emit odors during construction activities include exhaust from diesel construction equipment. However, because of the temporary nature of these emissions, the intermittent nature of construction activities, and the highly diffusive properties of DPM exhaust, nearby receptors would not be affected by diesel exhaust odors associated with project construction.

Odors from these sources would be localized and generally confined to the immediate area surrounding the proposed project site. The proposed project would utilize typical construction techniques, and the odors would be typical of most construction sites for a residential subdivision. As such, the proposed project would not cause odors that adversely affect a substantial number of people during the construction period; potential impacts during construction would be less than significant.

Operational-related Odors
The proposed project includes the construction and development of a new residential infill community consisting of a total of up to 58 townhomes and associated amenities, landscaping, and paving.

Operations of the proposed project could lead to odors from associated vehicle exhaust and outdoor cooking. However, such odors generated by project operation would be small in quantity and duration and would not pose an objectionable odor impact to nearby receptors. Land uses that are typically identified as sources of objectionable odors include landfills, transfer stations, sewage treatment plants, 306
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
48 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx composting facilities, feedlots, coffee roasters, asphalt batch plants, and rendering plants. The proposed residential project would not produce any offensive odor emitting end uses such as coffee roasting, composting, feed lots, refining, sewage treatment, or solid waste management and would not be considered an odor generator as identified in Table 5, and potential impacts during operation would be less than significant.

Summary
The proposed project would not result in other emissions (such as those leading to odors) adversely affecting a substantial number of people from construction or operations. Therefore, approval of the proposed project would not result in any significant effects relating to other emissions (such as odors), and impacts would be less than significant.

Mitigation Measures
None required.
307
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 49
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.4 Biological Resources
Would the project:
a) Have a substantial adverse effect, either
directly or through habitat modifications,
on any species identified as a
candidate, sensitive, or special-status
species in local or regional plans,
policies, or regulations, or by the
California Department of Fish and
Wildlife or United States Fish and
Wildlife Service?
b) Have a substantial adverse effect on
any riparian habitat or other sensitive
natural community identified in local or
regional plans, policies, and regulations
or by the California Department of Fish
and Wildlife or United States Fish and
Wildlife Service?
c) Have a substantial adverse effect on
State or federally protected wetlands
(including, but not limited to, marsh,
vernal pool, coastal, etc.) through direct
removal, filling, hydrological interruption,
or other means?
d) Interfere substantially with the
movement of any native resident or
migratory fish or wildlife species or with
established native resident or migratory
wildlife corridors, or impede the use of
wildlife nursery sites?
e) Conflict with any local policies or
ordinances protecting biological
resources, such as a tree preservation
policy or ordinance?
□ □ □
□ □ □
□ □ □
□ □ □
□ □ □
308
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
50 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact
f) Conflict with the provisions of an
adopted Habitat Conservation Plan,
Natural Community Conservation Plan,
or other approved local, regional, or
State habitat conservation plan?
Environmental Evaluation
The analysis in this section is based, in part, on a biological resources evaluation, which consisted of a field survey and a desktop survey conducted by FirstCarbon Solutions (FCS). Desktop survey results are included in Appendix B.

Setting
Methods
The biological resources evaluation included a review of existing environmental documentation for the project site and vicinity, including literature pertaining to the habitat requirements of special-status species with the potential to occur in the project vicinity, and Federal Register listings, protocols, and species data provided by the United States Fish and Wildlife Service (USFWS) and California Department of Fish and Wildlife (CDFW). FCS also reviewed topographic maps, aerial photographs, and published soil surveys and queried special-status species databases, including the USFWS Information for Planning and Consultation (IPaC) database,24 the California Natural Diversity Database (CNDDB),25 and the California Native Plant Society Electronic Inventory (CNPS Inventory).26
The biological resources evaluation included a field survey of the project site on April 7, 2026, to ascertain general site conditions and identify whether existing vegetation communities provide suitable habitat for special-status plant or wildlife species. 24 United States Fish and Wildlife Service (USFWS). 2026. Information for Planning and Consultation (IPaC). Website:
https://ecos.fws.gov/ipac/. Accessed April 14, 2026.
25 California Department of Fish and Wildlife (CDFW). 2026. CNDDB RareFind 5 California Natural Diversity Database Query for Special-Status Species. Website: https://wildlife.ca.gov/Data/CNDDB/Maps-and-Data. Accessed April 14, 2026.
26 California Native Plant Society (CNPS). 2026. California Native Plant Society Rare and Endangered Plant Inventory.

Website: http://www.rareplants.cnps.org/. Accessed April 14, 2026. □ □ □
309
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 51
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Results
A qualified FCS Biologist conducted a general biological survey of the project site on April 7, 2026, between approximately 10:00 a.m. and 11:10 a.m. Weather conditions during the field survey were sunny, with an average temperature around 65–69°F (degrees Fahrenheit) and wind speeds between 0 and 1 mph.

Environmental Setting
The project site is developed and is surrounded by Aliso Creek Road and commercial development to the west, Glenwood Drive and residential development to the north, and Argonaut and office development to the east and south. The project site is primarily paved or covered by an office building and is mostly flat, with slopes occurring along the western and northern boundaries. Ornamental trees are located along the boundaries or adjacent to the site on all sides, including hedgerows of pine (Pinus spp.) trees along the western and northern boundaries.

Would the project:
a) Have a substantial adverse effect, either directly or through habitat modifications, on any species identified as a candidate, sensitive, or special-status species in local or regional plans, policies, or regulations, or by the California Department of Fish and Wildlife or United States Fish and Wildlife Service? No impact. The project site is developed and is mostly paved or covered by an office building and contains ornamental trees located along the site boundaries and near the building. According to the CNDDB and CNPS Inventory, 83 special-status plant species have been recorded within 10 miles of the project site or within the San Juan Capistrano, California United States Geological Survey (USGS) 7.5-minute Topographic Quadrangle Map and the eight surrounding quadrangle search area that encompasses the project site (Appendix B). However, because of the urban/developed nature of the project site and lack of suitable habitat, all special-status plants that were documented in the region through the CNDDB and CNPS Inventory have no potential for occurrence (Appendix B, Table 1). Thus, special-status plants are not expected to occur on the project site.

Sixty special-status wildlife species were identified as occurring within 10 miles of the project site as recorded in the CNDDB or as identified in the USFWS IPaC database. Because of the urbanized/developed nature of the project site and vicinity, all special-status wildlife species identified in the database reviews were determined to have no potential for occurrence on the project site.

Since there is no potential for special-status plants or wildlife to occur on the project site, no mitigation measures are required.
b) Have a substantial adverse effect on any riparian habitat or other sensitive natural community identified in local or regional plans, policies, and regulations or by the California Department of Fish and Wildlife or United States Fish and Wildlife Service?
310
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
52 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx No impact. No riparian or other sensitive natural communities were recorded on or adjacent to the project site; therefore, the proposed project would have no impact on any riparian habitat or other sensitive natural community.
c) Have a substantial adverse effect on State or federally protected wetlands (including, but not limited to, marsh, vernal pool, coastal, etc.) through direct removal, filling, hydrological interruption, or other means? No impact. There were no waters or wetland features detected on the project site that would be considered potentially jurisdictional by the United States Army Corps of Engineers (USACE), nor any features that would be considered potentially jurisdictional by State regulatory agencies including the Regional Water Quality Control Board (RWQCB) and CDFW. Additionally, the project site does not contain vernal pools or features indicative of the historic presence of vernal pools. According to the Natural Resources Conservation Service (NRCS) Web Soil Survey (WSS),27 two soil types are mapped on the project site, Capistrano sandy loam and Cieneba-rock outcrop complex. While Cieneba soils are known to support vernal pools, there would be no potential for vernal pools to occur due to the developed nature of the site. Therefore, implementation of the proposed project would not result in impacts to State or federally protected wetlands, including vernal pools. No impacts would occur.
d) Interfere substantially with the movement of any native resident or migratory fish or wildlife species or with established native resident or migratory wildlife corridors, or impede the use of wildlife nursery sites?
Less than significant impact with mitigation incorporated. The project site is developed and is surrounded by urbanized areas and roads on all sides that limit wildlife movement through the project site. The project site itself does not serve as a wildlife movement corridor.

The project site contains vegetation, including trees within the site and along the boundaries, that could provide suitable nesting habitat for bird species protected under the Migratory Bird Treaty Act (MBTA) and the Fish and Game Code. These species include Cooper’s hawk and other avian species. Only avian species adapted to urbanized areas may use the trees on-site for nesting.

The proposed project would remove existing ornamental trees, shrubs, and landscaped vegetation within the developed portions of the site to accommodate grading and construction activities. Existing screening trees along the northern and western boundaries of the project site would be retained.

Trees and shrubs proposed for removal may provide nesting habitat for common urban-adapted bird species; however, replacement landscaping and tree planting would be incorporated throughout the project site, providing similar nesting and foraging opportunities over time.

The proposed trees would include native species, as well as climate-adaptive and drought-tolerant species. Additionally, the pine hedgerows along the western and northern boundaries of the site 27 United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). 2026. Web Soil Survey (WSS). Website: https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx. Accessed April 14, 2026. 311
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 53
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx would not be removed by the project. If ground-disturbing or vegetation-removing construction activities are initiated during the nesting season, they could disturb nesting and breeding birds on the ground surface, in trees and shrubs, and on structures on and adjacent to the project site, which would be considered a significant impact. Potential construction-related project impacts on specialstatus and migratory birds include destruction of eggs or occupied nests, mortality of young, and parental abandonment of nests with eggs or pre-fledged young birds. With the implementation of Mitigation Measure (MM) BIO-1a and MM BIO-1b, potential project impacts to nesting Cooper’s hawk and other native and migratory birds would be reduced to a less than significant level. e) Conflict with any local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance?
No impact. The General Plan for the City of Aliso Viejo contains the following two Ecological and Biological Resources policies in the Conservation/Open Space Element:

Policy COS-3.1 Support regional and sub-regional efforts to conserve ecological and biological resources.

Policy COS-3.2 Protect sensitive habitat areas and vegetation, particularly along Aliso Creek, within Aliso Woods, and within the Aliso and Wood Canyons Wilderness Park, by maintaining these resources as long-term open space.

The proposed project would not conflict with these policies. The existing screening trees along the western and northern perimeters of the project site would be preserved. The project would remove existing ornamental landscaping and trees located within the interior developed areas of the site to accommodate grading and construction of the proposed residential development. As stated above, nearly all trees removed by the proposed project would be replaced. Therefore, there are no local policies or ordinances protecting biological resources, such as a tree preservation policy or ordinance, with which the proposed project would conflict. No impact would occur. f) Conflict with the provisions of an adopted Habitat Conservation Plan, Natural Community Conservation Plan, or other approved local, regional, or State habitat conservation plan?
No impact. The project site is located within the boundaries of the County of Orange Natural Communities Conservation Plan (County of Orange NCCP) Habitat Conservation Plan (HCP), an HCP and NCCP authorized by the CDFW through the NCCP Act (California Fish and Game Code [FGC] § 2800) and Sections 2081 and 2084 of the California Endangered Species Act (CESA) and by the USFWS through Sections 7 and 10 of the Endangered Species Act.

The project site does not contain Covered Habitats or suitable habitat for Identified Species covered under the County of Orange NCCP HCP and therefore would not require coverage under the plan.

Thus, the proposed project would not conflict with an HCP, NCCP, or other approved local, regional, or State HCP. No impact would occur.
312
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
54 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Mitigation Measures
MM BIO-1a Nesting Bird Pre-construction Surveys
If ground-disturbing or vegetation-removing construction activities or tree removal is proposed during the breeding/nesting season for migratory birds (February 1 through September 15), a qualified Biologist shall conduct pre-construction surveys for special-status birds and other migratory birds within the construction area, including a 300-foot survey buffer (where accessible), no more than 3 days prior to the start of ground-disturbing activities in the construction area.

MM BIO-1b Avoidance of Active Avian Nests
If an active nest (i.e., occupied by eggs or fledglings) is located during preconstruction surveys or at any point during the construction phase of the proposed project, the City of Aliso Viejo shall be notified regarding the status of the nest.

Furthermore, construction activities shall be restricted as necessary to avoid disturbance of the nest until the eggs or fledglings no longer are in the nest or a qualified Biologist deems disturbance potential to be minimal. Restrictions may include establishment of exclusion zones (no ingress of personnel or equipment at a minimum radius of 300 feet around an active raptor nest and a 50-foot radius around an active migratory bird nest) or alteration of the construction schedule. 313
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 55
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.5 Cultural Resources
Would the project:
a) Cause a substantial adverse change in
the significance of a historical resource
pursuant to Section 15064.5?
b) Cause a substantial adverse change in
the significance of an archaeological
resource pursuant to Section 15064.5?
c) Disturb any human remains, including
those interred outside of dedicated
cemeteries?
Environmental Evaluation
Setting
This section describes the existing cultural setting and potential effects from project implementation on the project site and its surrounding area. The following discussion is based on records searches from the South Central Coastal Information Center (SCCIC) and the Native American Heritage Commission (NAHC) and a cultural resources pedestrian survey conducted by FCS. The nonconfidential SCCIC records search, pedestrian survey photographs, and NAHC correspondence are included in Appendix C.

South Central Coastal Information Center
On April 14, 2026, a records search/literature review was conducted at the SCCIC located at California State University, Fullerton. The purpose of this review was to access any existing cultural resources survey reports, archaeological site records, and historic maps to evaluate whether previously documented pre-contact or historic archaeological sites, architectural resources, cultural landscapes, or Tribal Cultural Resources (TCRs) exist within or near the project site. The records search/literature review was also conducted to evaluate whether the project site contains any historic properties listed on or determined eligible for listing on the National Register of Historic Places (NRHP), California Register of Historical Resources (CRHR), the California Historic Landmarks (CHL) list, the California Points of Historical Interest (CPHI) list, and the Built Environment Resource Directory (BERD) for Orange County. The results of the SCCIC records search indicate that seven pre-contact cultural resources have been recorded within the 0.5-mile search radius, one of which (P30-000414) is located within the project boundaries. In addition, there are 25 area-specific survey □ □ □
□ □ □
□ □ □
314
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
56 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx reports on file with the SCCIC, three of which (OR-00255, OR-00702, and OR-00926) partially address the project site and two of which (OR-00431 and OR-00705) address the project site entirely, indicating that the project site has been previously surveyed for cultural resources and produced positive results for cultural resources.

Native American Heritage Commission
On April 15, 2026, a records search request was sent to the NAHC in an effort to determine whether any sacred sites are listed on its Sacred Lands File (SLF) for the project site. On April 27, 2026, a response from the NAHC was received indicating that their SLF search came back positive for TCRs within the project site. The NAHC included a list of 28 Tribal representatives who may have additional knowledge of the project site. To ensure that all Native American knowledge and concerns over potential TCRs that may be affected by implementation of the proposed project are addressed, FCS sent letters to all 28 Tribal representatives on May 7, 2026. No responses have been received to date. Please note that this process is for information gathering purposes to support conclusions made within the cultural resources analysis and is not intended to satisfy the Lead Agency consultation requirements pursuant to Assembly Bill (AB) 52 or Senate Bill (SB) 18. See Section 2.18 Tribal Cultural Resources for discussions related to AB 52 and SB 18 consultation.

Cultural Resources Pedestrian Survey and Buried Site Potential On May 5, 2026, an FCS Archaeologist conducted a pedestrian survey for unrecorded cultural resources within the project site. The project site is predominantly developed with impervious surfaces with vegetated slopes located primarily along the northern and western perimeters. The perimeter of the project site is enclosed by a parking lot dedicated to the office building (constructed between 1988 and 1992) located at the center of the project site. Overview shots of the project site were taken from the northeast, northwest, southeast, and southwest corners that showcase the structure and the surrounding parking lot. Visibility of exposed soil was nonexistent since the entirety of the site is hardscaped; thus, inspection of the soil for cultural resources was not possible. Survey conditions were documented using digital photographs and field notes. No pre-contact or historic resources were found during the pedestrian survey.

In addition to the pedestrian survey, the potential for yet-identified cultural resources in the project vicinity was reviewed against geologic and topographic geographic information system (GIS) data for the general area and information from other nearby projects. The proposed project was evaluated against a set of criteria originally identified by a geoarchaeological overview that was prepared for the California Department of Transportation (Caltrans) Districts 6 and 9.28 This study mapped the “archaeological sensitivity,” or potential to support the presence of buried pre-contact archaeological deposits, based on geology and environmental parameters including distance to water and landform slope. The methodology used in the study is applicable to other parts of California, such as the Bay Area, and generally concluded that sites consisting of flat, Holocene-era deposits in close proximity to 28 Meyer, J., D. Craig Young, and Jeffrey S. Rosenthal. 2010. Volume I: A Geoarchaeological Overview and Assessment of Caltrans District 6 and 9, Cultural Resources Inventory of Caltrans District 6/9 Rural Conventional Highways. Submitted to Central California Department of Transportation, District 6. 315
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 57
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx natural water resources had a moderate to high probability of containing subsurface archaeological deposits when compared to earlier Pleistocene deposits situated on slopes or further away from drainages, lakes, and rivers.

According to the isotopic gravity map with geology of Santa Ana, Southern California,29 the surface of the project site rests entirely on alluvial valley deposits (Holocene to late Pleistocene; Qya). Applying the criteria set forth in Meyer et al., all Holocene-era deposits have the potential to contain archaeological deposits, which increases with the ease of the slope and proximity to water resources.

The terrain of the project site is relatively flat, with the exception of the northern and western portions of the project site, which include landscaped slopes, and the closest water source is Aliso Creek, located approximately 0.8 mile southeast of the project site. In addition, positive results from the NAHC SLF search for TCRs and the positive SCCIC results for cultural resources indicate a moderate to high potential for unanticipated buried cultural resources to be impacted by project construction.

Cultural Resources
Would the project:
a) Cause a substantial adverse change in the significance of a historical resource pursuant to Section 15064.5?
No impact. Historical resources in this context refer to the built environment, mainly buildings and structures over 50 years in age that may be eligible for inclusion on the CRHR or NRHP. Records search results conducted at the SCCIC did not identify any historical resources within the 0.5-mile search radius, nor within the proposed project boundaries. Additionally, the results of the pedestrian survey indicated that the project site consists of an enclosed parking lot and office building that was constructed between 1988 and 1992. As such, no historical resources were identified during the pedestrian field survey. Thus, the proposed project would not cause a substantial adverse change in the significance of any such known resources. No mitigation measures are required, and there would be no impact to historical resources.
b) Cause a substantial adverse change in the significance of an archaeological resource pursuant to Section 15064.5?
Less than significant impact with mitigation incorporated. Results from the SCCIC indicate that five pre-contact archaeological resources are recorded within a 0.5-mile radius of the project site, of which one pre-contact resource (P-30-000414) is recorded within the project boundaries. There are no historic era archaeological resources located in or within a 0.5-mile radius of the project site. The results of the pedestrian survey did not locate or identify any archaeological resources due to the lack of soil visibility across the project site. Given the results of the records searches, the potential to 29 Langenheim, V.E., Tien-Chang Lee, Shawn Biehler, A.C. Jachens, and D.M. Morton. 2006. Isotopic gravity map with geology of the Santa Ana 30’ x 60’ quadrangle, southern California. United States Geological Survey. Map. Scale 1:100,000.
316
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
58 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx impact unidentified archaeological resources is considered moderate to high. It is possible that earthmoving activities associated with project construction could encounter previously undiscovered archaeological resources. Archaeological resources can include but are not limited to stone, bone, wood, or shell artifacts or features, including hearths and structural elements. Damage or destruction of these resources would have a potentially significant impact. MM CUL-1 would require a Worker Environmental Awareness Program (WEAP) training, a site survey conducted by a qualified Archaeologist, and archaeological monitoring. MM CUL-2 would require consultation with a qualified Archaeologist in the event that buried archaeological resources are discovered during construction, as well as inadvertent discovery procedures. Implementation of MM CUL-1 and MM CUL-2 would ensure that potential impacts to archaeological resources will be reduced to a level of less than significant.
c) Disturb any human remains, including those interred outside of formal cemeteries? Less than significant impact with mitigation incorporated. While no formal cemeteries or areas containing human remains are known to be in the project site’s vicinity, the possibility always exists that construction-related ground disturbance may uncover previously undiscovered human remains.

In the unlikely event such a discovery is made, CEQA Guidelines Section 15064.5, Health and Safety Code Section 7050.5, and Public Resources Code Sections 5097.94 and 5097.98 must be followed.

Additionally, implementation of MM CUL-3, which details inadvertent discovery procedures, would reduce potential impacts of previously undiscovered human remains to a less than significant level.

Mitigation Measures
MM CUL-1 Prior to the initiation of construction activities, all construction personnel conducting ground disturbance at the site shall be provided a Worker Environmental Awareness Program (WEAP) cultural resources “tailgate” training. The training shall include visual aids, a discussion of applicable laws and statutes relating to archaeological resources, types of resources that may be found within the project site, and procedures to be followed in the event such resources are encountered. The training shall be conducted by an Archaeologist who meets the Secretary of the Interior’s Professional Qualification Standards for archaeology.

An Archaeologist who meets the Secretary of the Interior’s Professional Qualification Standards for archaeology shall conduct an updated survey of the site following demolition and exposure of native soils and prior to any project-related trenching or grading to check for the inadvertent exposure of cultural materials.

This shall be followed by archaeological monitoring during the grading and trenching phase of the proposed project. At the completion of these phases, archaeological monitoring shall be reduced to periodic “spot checks.” In the event exposed soils indicate cultural materials may be present, this may be followed by regular or full-time archaeological monitoring as determined by the Archaeologist. 317
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 59
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx MM CUL-2 In the event that buried archaeological resources are discovered during construction, operations shall stop within a 100-foot radius of the find and an Archaeologist who meets the Secretary of Interior’s Professional Qualification Standards for archaeology shall be consulted to determine whether the resource requires further study. The qualified Archaeologist shall make recommendations to the Lead Agency on the measures that shall be implemented to protect the discovered resources, including but not limited to excavation of the finds and evaluation of the finds in accordance with Section 15064.5 of the CEQA Guidelines. Potentially significant cultural resources consist of but are not limited to stone, bone, fossils, wood, or shell artifacts or features, including hearths, structural remains, or historic dumpsites. Any previously undiscovered resources found during construction within the project area shall be recorded on appropriate California Department of Parks and Recreation (DPR) forms and evaluated for significance in terms of CEQA criteria. If the resources are determined to be unique historic resources as defined under Section 15064.5 of the CEQA Guidelines, mitigation measures shall be identified by the monitor and recommended to the Lead Agency. Appropriate mitigation measures for significant resources could include avoidance or capping, incorporation of the site in green space, parks, or open space, or data recovery excavations of the finds. The Lead Agency, along with other relevant or Tribal officials, shall be contacted upon the discovery of cultural resources to begin coordination on the disposition of the find(s).

Treatment of any significant cultural resources shall be undertaken with the approval of the Lead Agency. No further grading shall occur in the area of the discovery until the Lead Agency approves the measures to protect these resources. Upon coordination with the Lead Agency, any archaeological artifacts recovered shall be donated to an appropriate Tribal custodian or a qualified scientific institution where they would be afforded applicable cultural resources laws and guidelines.

MM CUL-3 In the event of the accidental discovery or recognition of any human remains, CEQA Guidelines Section 15064.5, Health and Safety Code Section 7050.5, and Public Resources Code Section 5097.94 and Section 5097.98 shall be followed. If during the course of project construction, there is accidental discovery or recognition of any human remains, the following steps shall be taken:

1. There shall be no further excavation or disturbance of the site where human remains are discovered and/or any nearby area reasonably suspected to overlie adjacent human remains until the County Coroner is contacted to determine whether the remains are Native American and if an investigation of the cause of death is required. If the Coroner determines the remains to be Native American, the Coroner shall contact the Native American Heritage Commission (NAHC) within 24 hours, and the NAHC shall identify the person or persons it believes to be the Most Likely Descendant (MLD) of the deceased Native American. The MLD may make recommendations to the landowner or the person responsible for the excavation work within 48 hours, for means of treating or disposing of, with 318
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
60 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx appropriate dignity, the human remains, and any associated grave goods as provided in Public Resources Code Section 5097.98.

2. Where the following conditions occur, the landowner or his or her authorized representative shall rebury the Native American human remains and associated grave goods with appropriate dignity either in accordance with the recommendations of the MLD or on the project site in a location not subject to further subsurface disturbance:
• The NAHC is unable to identify an MLD or the MLD failed to make a recommendation within 48 hours after being notified by the commission. • The descendant identified fails to make a recommendation. • The landowner or his authorized representative rejects the recommendation of the descendant, and mediation by the NAHC fails to provide measures acceptable to the landowner.
319
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 61
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.6 Energy
Would the project:
a) Result in potentially significant
environmental impact due to wasteful,
inefficient, or unnecessary consumption
of energy resources, during project
construction or operation?
b) Conflict with or obstruct a State or local
plan for renewable energy or energy
efficiency?
Environmental Evaluation
Setting
Energy use, especially through fossil fuel consumption and combustion, relates directly to environmental quality since it can adversely affect air quality and generate greenhouse gas (GHG) emissions that contribute to climate change. Electrical power is generated through a variety of sources, including fossil fuel combustion, hydropower, wind, solar, biofuels, and others. Natural gas is widely used to heat buildings, prepare food in restaurants and residences, and fuel vehicles, among other uses. Fuel use for transportation is related to the fuel efficiency of cars, trucks, and public transportation; choice of different travel modes such as auto, carpool, and public transit; and miles traveled by these modes and is generally based on petroleum-based fuels, such as diesel and gasoline. Electric vehicles (EVs) may not have any direct emissions but do have indirect emissions via the source of electricity generated to power the vehicle. Construction and routine operation and maintenance of transportation infrastructure also consume energy. Southern California Edison (SCE) provides electricity and Southern California Gas Company (SoCalGas) provides natural gas service within the City of Aliso Viejo.

Would the project:
a) Result in potentially significant environmental impact due to wasteful, inefficient, or unnecessary consumption of energy resources, during project construction or operation?
Less than significant impact. A discussion of the proposed project’s anticipated energy usage is presented below. Energy use consumed by the proposed project was estimated and includes □ □ □
□ □ □
320
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
62 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx electricity and fuel consumption for project construction and operation. Energy calculations are included as part of Appendix A.

Short-term Construction Impacts
For the purpose of this analysis, construction of the proposed project was estimated to begin in March 2027 and conclude in November 2028 and was modeled based on an applicant-provided preliminary schedule (see Appendix A). If the construction schedule moves to later years, construction emissions would likely decrease because of improvements in technology and more stringent regulatory requirements as older, less efficient equipment is replaced by newer and cleaner equipment. The proposed project would require demolition, site preparation, grading, building construction, architectural coating, and paving. The construction phase would require energy for the manufacture and transportation of building materials, preparation of the site (e.g., site clearing and grading), and the actual construction of the buildings. Petroleum-based fuels such as diesel fuel and gasoline would be the primary sources of energy for these tasks.

The types of on-site equipment used during construction of the proposed project could include gasoline- and diesel-powered construction and transportation equipment, including trucks, front-end loaders, forklifts, and cranes. On-site, off-road construction equipment is estimated to consume a total of approximately 45,858 gallons of fuel over the entire construction duration (Appendix A).

Fuel use associated with construction vehicle trips generated by the proposed project was also estimated; trips include construction worker trips, haul truck trips for material transport, and vendor trips for construction material deliveries. Fuel use from these vehicles traveling to and from the project site was based on (1) the projected number of trips the proposed project would generate during construction, (2) average trip distances by trip type, and (3) fuel efficiencies estimated in the ARB Emissions Factors (EMFAC) mobile source emission model. In total, the proposed project is estimated to generate approximately 302,890 VMT and a combined 16,706 gallons of gasoline and diesel for vehicle travel during construction.

Other equipment could include construction lighting, field services (office trailers), and electrically driven equipment such as pumps and other tools. Municipal Code Section 8.12.070 permits construction, repair, remodeling, or grading activities during daytime hours, specifically between 7:00 a.m. and 8:00 p.m. on weekdays and between 8:00 a.m. and 8:00 p.m. on Saturdays, with no construction allowed on Sundays or federal holidays. As on-site construction activities would be restricted during these hours, it is anticipated that the use of construction lighting would be minimal.

The overall construction processes are already designed to be efficient in order to avoid excess monetary costs. For example, equipment and fuel are not typically used wastefully because of the added expense associated with renting the equipment, maintaining it, and fueling it. Therefore, the opportunities for future efficiency gains during construction are limited. Therefore, it is anticipated that the construction phase of the proposed project would not result in wasteful, inefficient, and unnecessary consumption of energy. Construction-related energy impacts would be less than significant.
321
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 63
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Long-term Operational Impacts
The proposed project would consume energy as part of building operations and transportation activities. Operation of the proposed project would consume an estimated 478,814 kilowatt hours (kWh) of electricity. The proposed residential buildings would be built all-electric and the proposed project would install solar photovoltaic (PV) systems that would generate renewable energy, consistent with the 2025 Building Energy Efficiency Standards. Therefore, the proposed project would not impair, but rather would include the use of renewable energy. In addition, the proposed project’s buildings would be designed and constructed in accordance with the City’s latest adopted energy efficiency standards, which are based on the State’s Building Energy Efficiency Standards. These are widely regarded as the most advanced Building Energy Efficiency Standards, and compliance would ensure that building energy consumption would not be wasteful, inefficient, or unnecessary.

Additionally, the CBC requires new residential development to include energy efficiency features related to building envelope, mechanical systems (e.g., heating, ventilation, and air conditioning [HVAC] and water heating systems), and indoor and outdoor lighting. CALGreen requires all new garages for the proposed homes to install electrical panels of adequate size to support the installation of EV charging systems. The proposed project would install solar PV systems in compliance with Title 24, Part 6, California’s Energy Code. As such, compliance with the CBC Title 24 standards and CALGreen would ensure that the proposed project would not interfere with the ability to include renewable energy sources. As it relates to energy use from vehicular travel, the proposed 58-unit residential project is estimated to generate approximately 356 daily vehicle trips. Project-related travel would consume an estimated 44,836 gallons of gasoline, diesel, and compressed natural gas and 63,330 kWh of electricity annually. Because these trips would support routine residential activities, utilize the existing transportation network, and would not result from inefficient site design or circulation patterns, transportation energy consumption would not be wasteful, inefficient, or unnecessary. Impacts would be less than significant.
b) Conflict with or obstruct a State or local plan for renewable energy or energy efficiency?
Less than significant impact. The proposed project would be evaluated with existing State energy standards and General Plan energy conservation policies. SCE would provide electricity to the proposed project. In 2024, the latest year with available data, SCE obtained 35 percent of its electricity from renewable energy sources. SCE also offers a Green Rate 50 percent option that sources 67 percent of its power mix from eligible renewable energy sources and a Green Rate 100 percent option that sources 100 percent of its power mix from eligible renewable energy sources.30 SCE would be required to meet the future objective of sourcing 60 percent of its electricity from renewable energy sources by 2030. Additionally, the proposed project would replace an existing office development that, although currently vacant, continues to consume a limited amount of electricity for building maintenance and related functions. As a result, a portion of the proposed project's operational energy demand would be offset by the elimination of this existing energy use. 30 Southern California Edison (SCE). 2024 Power Content Label. Website:
https://www.energy.ca.gov/filebrowser/download/9168. Accessed May 12, 2026. 322
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
64 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Furthermore, as an all-electric development, the proposed project would support California's transition toward lower-carbon energy consumption.

The proposed residential project would be designed in accordance with Title 24, California’s Energy Efficiency Standards for residential buildings. These standards include minimum energy efficiency requirements related to building envelope, mechanical systems (e.g., HVAC and water heating systems), and indoor and outdoor lighting. CALGreen requires all new garages for the proposed homes to install electrical panels of adequate size to support the installation of EV charging systems.

Therefore, it is anticipated that the proposed project would be designed and built to minimize transportation energy through the promotion of the use of electric-powered vehicles, and it is anticipated that existing and planned capacity and supplies of transportation fuels would be sufficient to support the proposed project’s demand. The proposed project would install solar PV systems in compliance with Title 24, Part 6, California’s Energy Code.

The General Plan Conservation/Open Space Element contains the following policies related to energy conservation.

Energy Supply and Conservation
Policy COS-6.1 Encourage green building designs for new construction and renovation projects within the City.

Policy COS-6.2 Coordinate with regional and local energy suppliers to ensure adequate supplies of energy to meet community needs, implement energy conservation and public education programs, and identify alternative energy sources where appropriate.

Policy COS-6.3 Encourage building orientations and landscaping that enhance natural lighting and sun exposure.

Policy COS-6.4 Encourage expansion of neighborhood-level products and services and public transit opportunities throughout the City to reduce automobile use.

While several of these policies are city-level requirements or voluntary, compliance with Title 24 standards and other applicable regulations would ensure that the proposed project would not conflict with any of the energy conservation policies related to the proposed project’s building, mechanical systems, and indoor and outdoor lighting.

The proposed project would comply with existing State energy standards and with energy conservation policies contained in the General Plan. As such, the proposed project would not conflict with State or local renewable energy or energy efficiency objectives. Potential impacts would be less than significant.

Mitigation Measures
None required.
323
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 65
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.7 Geology and Soils
Would the project:
a) Directly or indirectly cause potential substantial adverse effects, including the risk of loss, injury, or death involving:
i) Rupture of a known earthquake
fault, as delineated on the most
recent Alquist-Priolo Earthquake
Fault Zoning Map issued by the
State Geologist for the area or
based on other substantial evidence
of a known fault ? Refer to Division
of Mines and Geology Special
Publication 42.
ii) Strong seismic ground shaking?
iii) Seismic-related ground failure,
including liquefaction?
iv) Landslides?
b) Result in substantial soil erosion or the
loss of topsoil?
c) Be located on a geologic unit or soil that
is unstable, or that would become
unstable as a result of the project, and
potentially result in on- or off-site
landslide, lateral spreading, subsidence,
liquefaction or collapse?
d) Be located on expansive soil, as
defined in Table 18-1-B of the Uniform
Building Code (1994), creating
substantial direct or indirect risks to life
or property?
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
324
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
66 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact
e) Have soils incapable of adequately
supporting the use of septic tanks or
alternative wastewater disposal systems
where sewers are not available for the
disposal of wastewater?
f) Directly or indirectly destroy a unique
paleontological resource or site or
unique geologic feature?
Environmental Evaluation
Setting
Geology and Soils
The analysis in this section is based, in part, on the Geotechnical Investigation prepared by Alta California Geotechnical, Inc., on September 26, 2025, included in Appendix D of this document.31 The report concluded that the proposed grading and development is considered geotechnically feasible, provided the recommendations in the report are implemented during design, grading, and construction.

Paleontological Resources
The analysis in this section is based, in part, on the Cultural Resources Due Diligence Memorandum prepared by FCS on July 3, 2024, for the 95 Argonaut Project, located 550 feet (0.1 mile) east of the project site.32 Because of the close proximity of the proposed project to the 95 Argonaut Project, the results of the paleontological records search for the 95 Argonaut Project were used because the project site has the same 0.5-mile search radius for paleontological resources.

The Cultural Resources Due Diligence Memorandum included paleontological records searches of the San Diego Natural History Museum (The Nat) online fossil locality database and the Natural History Museum of Los Angeles County (NHM) collections, which are available online through the 31 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
32 FirstCarbon Solutions (FCS). 2024. Cultural Resources Due Diligence Memorandum for the Proposed Argonaut Project, City of Aliso Viejo, Orange County, California. July 3. □ □ □
□ □ □
325
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 67
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Integrated Digitized Biocollections (iDigBio), and the University of California Museum of Paleontology (UCMP) online fossil locality database.

Paleontological resources are the fossilized remains of plants and animals, including vertebrates (animals with backbones; fish, amphibians, reptiles, birds, mammals, etc.), invertebrates (animals without backbones; starfish, clams, coral, cephalopods, etc.), microscopic plants and animals (microfossils), and trace fossils/ichnofossils (i.e., footprints, burrows, etc.). Fossils are valuable, nonrenewable, scientific resources used to document the existence of extinct life forms and to reconstruct the environments in which they lived. Fossils are preserved in sedimentary rocks and, despite the abundance of these rocks and the vast numbers of organisms that have lived through time, preservation of plant or animal remains as fossils is a rare occurrence.

The Society of Vertebrate Paleontology (SVP) defines a significant fossil resource as, “identifiable vertebrate fossils, large or small, uncommon invertebrate, plant, and trace fossils, and other data that provide taphonomic, taxonomic, phylogenetic, paleoecologic, stratigraphic, and/or biochronologic information.” Paleontological resources are considered older than recorded human history and/or older than middle Holocene (i.e., older than about 5,000 radiocarbon years).33 The sensitivity of an area with respect to paleontological resources hinges on its geologic setting and whether significant fossils have been discovered in the area or in similar geologic units.

Would the project:
a) Directly or indirectly cause potential substantial adverse effects, including the risk of loss, injury, or death involving:
i) Rupture of a known earthquake fault, as delineated on the most recent AlquistPriolo Earthquake Fault Zoning Map issued by the State Geologist for the area or based on other substantial evidence of a known fault? Refer to Division of Mines and Geology Special Publication 42.

Less than significant impact. Seismically induced ground rupture is defined as the physical displacement of surface deposits in response to an earthquake’s seismic waves. Ground rupture is most likely to occur along active faults and typically occurs during earthquakes of magnitude 5.0 or higher. Ground rupture only affects the area immediately adjacent to a fault.

The project site is located in Southern California, which is a seismically active area. The type and magnitude of seismic hazards affecting the project site are dependent on the distance to the causative fault and the intensity and magnitude of the seismic event. The seismic hazards may be primary, such as surface rupture and/or ground shaking, or secondary, such as liquefaction and/or ground lurching.
33 Society of Vertebrate Paleontology (SVP). 2010. Standard Procedures for the Assessment and Mitigation of Adverse Impacts to Paleontological Resources. Society of Vertebrate Paleontology Impact Mitigation Guidelines Revision Committee.
326
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
68 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Active faults are not known to exist within the project site, as discussed in the Geotechnical Investigation. According to the Geotechnical Investigation, the project site is not within a California State-designated earthquake fault zone, and the potential for fault surface rupture is considered very low. The nearest fault zone to the project site is the San Joaquin Hills Fault Zone, located approximately 2.2 miles to the west.34 According to California Geological Survey’s (CGS’s) most recent Alquist-Priolo Earthquake Fault Zone and Seismic Hazard Zone Map, a known earthquake fault is not located near the project site or known to traverse the project site.35 Additionally, the General Plan Safety Element states that there are no known fault zones or seismic zones in the City.36 Therefore, impacts related to rupture of a known earthquake fault would be less than significant.
ii) Strong seismic ground shaking?
Less than significant impact. The City, as well as most of Southern California, is located in a region of historic seismic activity. Strong levels of seismic ground shaking can cause damage to buildings.

The intensity of ground shaking on the project site would depend upon the earthquake’s magnitude, distance to the epicenter, and geology of the area between the project site and epicenter.

According to the Geotechnical Investigation, ground shaking hazards would be associated with activity from the San Joaquin Hills Fault Zone and the Newport-Inglewood Fault Zone, located 2.2 miles and 7.1 miles to the west, respectively.37 During seismic events, the project site could experience ground shaking hazards associated with the faults described above.

The Geotechnical Investigation noted that the project site has the potential for seismic shaking hazards during an earthquake event. Pursuant to Municipal Code Chapter 13.02, Building Regulations, the City has adopted the 2025 CBC. The proposed project would be required to comply with all applicable regulations in the 2025 CBC, as amended by the Municipal Code, which includes design requirements to minimize the effects of seismic ground shaking. The proposed project would also be subject to the current CBC, as adopted by the City’s Planning and Building Department, with respect to seismic design parameters. Conformance with these standard engineering practices and design criteria would reduce the effects of seismic ground shaking.

Additionally, Municipal Code Chapter 13.08.170, Soil Engineering and Engineering Geology Reports, requires implementation of the site-specific recommendations provided in the Geotechnical Investigation, including seismic design parameters. The site-specific design recommendations would be required to be incorporated into project construction plans, including grading plans, as conditions 34 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
35 California Geological Survey (CGS). 2026. Earthquake Zones of Required Investigation Map. Website: https:// maps.conservation.ca.gov/cgs/informationwarehouse/eqzapp/?print_preview=true. Accessed April 10, 2026. 36 City of Aliso Viejo. 2004. General Plan Safety Element. Website:
https://www.avcity.org/DocumentCenter/View/395/Safety-Element-PDF. Accessed April 10, 2026. 37 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
327
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 69
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx of approval (COA GEO-1a) pursuant to Municipal Code Chapter 13.08.170. Implementation of COA GEO-1a would ensure that recommendations concerning earthwork, grading and fill, foundations, seismic design parameters, corrosivity, and drainage are implemented during design, grading, and construction. Compliance with Municipal Code Chapter 13.08.170 and the 2025 CBC would reduce potential impacts related to strong seismic ground shaking to a less than significant level.

Following compliance with standard engineering practices and through implementation of COA GEO1a, potential impacts concerning exposure of people or structures to potential adverse effects involving strong seismic ground shaking would be less than significant. iii) Seismic-related ground failure, including liquefaction? No impact. Liquefaction is a phenomenon where earthquake-induced ground vibrations increase the pore pressure in saturated, granular soils until it is equal to the confining, overburden pressure. When this occurs, the soil can completely lose its shear strength and enter a liquefied state. For liquefaction to occur, a project site must be subject to three factors: underlying loose, coarse-grained (sandy) soils, a groundwater depth of approximately 25 feet, and a potential for seismic shaking from nearby large-magnitude earthquakes.

The project site is not located in a Liquefaction Hazard Zone.38 According to the CGS, the nearest mapped Liquefaction Hazard Zone is located approximately 0.51 mile northwest of the project site.39 The Geotechnical Investigation concluded that there is no potential for liquefaction since the project site is not located within a State-designated liquefaction zone and no groundwater was encountered during soil boring investigations performed. Furthermore, General Plan Figure S-1, Safety Policy Map, indicates that the project site is not located within an area with liquefaction potential.40 Therefore, the proposed project would not cause potential substantial adverse effects involving seismic-related ground failure, including liquefaction. There would be no impact. iv) Landslides?
Less than significant impact. Landslides can occur if ground shaking and/or heavy rainfall disturb areas of steep slopes consisting of unstable soils. According to the General Plan, earthquake-induced landslides have the potential to occur within the City. Generally, these types of failures consist of rock falls, landslides, and debris flows. The potential for earthquake-induced landslides generally occurs in areas of steep slopes consisting of unstable soils disturbed by ground shaking and/or heavy rainfall.41 38 California Geological Survey. 2024. Earthquake Zones of Required Investigation Map. Website:
https://maps.conservation.ca.gov/cgs/informationwarehouse/eqzapp/?print_preview=true. Accessed April 10, 2026. 39 Ibid.
40 City of Aliso Viejo. 2004. General Plan. Safety Element. Figure S-1: Safety Policy Map. https://avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 10, 2026. 41 City of Aliso Viejo. 2004. General Plan, Safety Element. Website: https://avcity.org/DocumentCenter/View/395/SafetyElement-PDF. Accessed April 10, 2026. 328
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
70 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx The sloped areas along the northern and western boundaries of the project site are mapped as having landslide potential by the General Plan, as shown in the General Plan’s Figure S-1, Safety Policy Map.
42 According to the Geotechnical Investigation, this slope is approximately 50 feet and was completed during the grading of the existing structures and adjacent streets.43 The Geotechnical Investigation conducted a slope stability analysis and determined that no visible instabilities were observed and noted that the proposed structures have been designed to comply with the latest CBC setback requirements from the toe of the slope.44
As previously described, COA GEO-1a would be implemented pursuant to Municipal Code Chapter

13.08.170 and 2025 CBC standards. Implementation of COA GEO-1a would reduce the potential for landslide hazards by incorporating site-specific design recommendations into project construction plans and grading plans related to slope stability. In addition, implementation of COA GEO-1b would require grading activities adjacent to the existing slopes along the western and northern boundaries of the site to be observed by a licensed California Geotechnical Engineer or Certified Engineering Geologist. COA GEO-1b would ensure that, if necessary, supplemental recommendations would be incorporated into construction and grading plans to address potential impacts related to landslide susceptibility.

Furthermore, implementation of both COA GEO-1a and COA GEO-1b would ensure that on-site runoff is controlled and directed off-site in a nonerosive manner and that site drainage and slopes are maintained over the life of the proposed project and would establish minimum setback criteria for descending slopes. Additionally, as described under Impact 2.9(c)(i), Hydrology and Water Quality, the proposed project would also be required to implement a Stormwater Pollution Prevention Plan (SWPPP) during construction requiring the incorporation of Best Management Practices (BMPs) and would maintain existing on-site drainage and vegetation during operations.

Through implementation of COA GEO-1a and COA GEO-1b, in addition to BMPs implemented through a project-specific SWPPP, the proposed project would avoid substantial adverse impacts associated with landslides. Therefore, the proposed project would not result in significant impacts related to landslides. Impacts would be less than significant. b) Result in substantial soil erosion or the loss of topsoil? Less than significant impact. The Geotechnical Investigation indicates that the project site is underlain by silty sandstone, clayey sandstone, sandy claystone, sandstone, and claystone of the Miocene-age Monterey Formation.45 This unit was logged to a depth of 51.5 feet below ground surface and is overlain by a thin layer of asphalt. The Geotechnical Investigation determined that the 42 City of Aliso Viejo. 2004. General Plan. Safety Element. Figure S-1: Safety Policy Map. https://avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 10, 2026. 43 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
44 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
45 Ibid.
329
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 71
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx upper portions of alluvium are compressible and thus are not suitable to support the proposed structures.46 Therefore, the proposed project would be required to implement the site-specific recommendations referenced in the Geotechnical Investigation related to soil removal and recompaction and final slab and foundations.

During construction, the proposed project would also be required to comply with erosion and siltation control measures outlined in Municipal Code Chapter 13.08, Grading and Excavation Code, which requires that excavations and fills that may affect drainage and watercourses be performed in accordance with good engineering practice, thereby reducing to a minimum the hazards and damage to public and private property. This would include measures such as using sandbags or straw bales as temporary erosion control.

Additionally, the proposed project would comply with the National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges Associated with Construction and Land Disturbance Activities (Order No. 2009-0009DWQ, and all subsequent amendments) (Construction General Permit); see Impact 2.10(a). The Construction General Permit requires development and implementation of a SWPPP and monitoring plan, which must include erosion and sediment control BMPs that would meet or exceed measures required by the Construction General Permit to control potential construction-related pollutants. Following compliance with the established regulatory framework, including Municipal Code Chapter 13.08 and Chapter 13.08.170 and the Construction General Permit, potential impacts concerning soil erosion and loss of topsoil would be less than significant.
c) Be located on a geologic unit or soil that is unstable, or that would become unstable as a result of the project, and potentially result in on- or off-site landslide, lateral spreading, subsidence, liquefaction, or collapse?
Less than significant impact. As discussed in Impact 2.7(a), the project site would not be subject to significant impacts from seismically induced liquefaction. As previously mentioned under Impact

2.7(a)(iv), to address potential impacts regarding landslides, the proposed project would implement COA GEO-1a and COA GEO-1b.

Lateral spreading is a type of ground deformation that occurs when surface material extends or spreads on gentle slopes.47 Ground shaking, especially when inducing liquefaction, may cause lateral spreading toward unsupported slopes.

Subsidence is a gradual settling or sudden sinking of Earth's surface that occurs when the withdrawal of groundwater, oil, or natural gas vertically displaces a large portion of land. Soils that are particularly subject to subsidence include those with high silt or clay content. 46 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
47 United States Geological Survey (USGS). Lateral Spread. https://www.usgs.gov/media/images/lateral-spread. Accessed April 10, 2026.
330
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
72 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Hydro-consolidation is the effect of introducing water into soil that is prone to collapse. Upon loading and initial wetting, the soil structure and apparent strength are altered, resulting in almost immediate settlement.48 According to the Geotechnical Investigation, based on laboratory testing, there is a minimum potential for hydro-collapse as a result of the proposed project.49 Sedimentary bedrock of the Monterey Formation that is successively overlain by unconsolidated alluvium underlies the project site. The Geotechnical Investigation evaluated site conditions and identified the need for removal and recompaction of all weathered/unsuitable fill materials in order to provide competent subgrade and bearing conditions for the proposed structural slabs and foundations. Accordingly, the Geotechnical Investigation recommends removal and recompaction of the upper 5 feet of existing on-site soils beneath the proposed structures and removal beneath the building pads of the proposed structures to extend to a minimum of 5 feet laterally beyond the building footprint. It is recommended to remove and recompact the upper 2 feet of existing soils underneath parking lots and drive aisles and for cuts that are less than 2 feet underneath street areas. A Geotechnical Consultant would be required to observe all removal and over-excavation bottoms prior to the placement of fill. If unsuitable soils such as undocumented artificial fill is exposed upon the completion of the removals recommended above, additional removals may be required.

Earthwork would be required to meet compaction standards and import soils must be approved by the project Geotechnical Consultant.

Pursuant to Municipal Code Chapter 13.08.170, Soil engineering and engineering geology reports, the proposed project would incorporate all site-specific recommendations of the Geotechnical Investigation as COA GEO-1a, which would address any identified potential soil and geologic hazards. The proposed project would also implement additional design recommendations related to landslide susceptibility through implementation of COA GEO-1b. Furthermore, the proposed project would be required to comply with all applicable regulations in the 2025 CBC as amended by the Municipal Code, which includes design requirements to mitigate the effects of potential soil and geologic hazards, including landslide, lateral spreading, subsidence, liquefaction, and seismic settlement. The City would review project design and construction plans for compliance with the CBC and the Municipal Code prior to construction activities. Thus, compliance with the City’s established regulatory framework and standard engineering practices and design criteria, which would be verified through the City’s plan review process, would ensure potential impacts associated with a geologic unit or soil that is unstable or would become unstable at the project site would be less than significant. d) Be located on expansive soil, as defined in Table 18-1-B of the Uniform Building Code (1994), creating substantial direct or indirect risks to life or property? Less than significant impact. The Geotechnical Investigation anticipated on-site soils are diatomaceous soils, consisting of a low density and high moisture content, and have a low to medium 48 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
49 Ibid.
331
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 73
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx expansion potential.
50 As such, the recommendations provided in the Geotechnical Investigation include design recommendations for post-tensioned slabs, select backfill, subgrade moisture conditioning, and concrete slab reinforcement. Municipal Code Chapter 13.08.170 requires implementation of the recommendations provided in the Geotechnical Investigation. This requirement is incorporated into the proposed project as COA GEO-1a. Additionally, the City’s Building Division would review construction plans to verify compliance with standard engineering practices, the Municipal Code, and the CBC. Compliance with the Municipal Code and the City’s established regulatory framework; standard engineering practices, which would be verified through the City’s plan review process; and the CBC would ensure potential impacts related to expansive soil are less than significant.
e) Have soils incapable of adequately supporting the use of septic tanks or alternative wastewater disposal systems where sewers are not available for the disposal of wastewater?
No impact. Sewers are available for disposal of the proposed project’s wastewater. The proposed project would connect to the existing sanitary sewer system for wastewater disposal and would not include the use of septic tanks. Therefore, no impacts would occur, and no mitigation is required. f) Directly or indirectly destroy a unique paleontological resource or site or unique geologic feature?
Less than significant impact with mitigation incorporated. Geologic mapping indicates that the project site is underlain by sedimentary bedrock of Miocene-age Monterey Formation that is successively overlain by a thin layer of asphalt fill. Based on soil borings collected at the project site, sand, sandstone, clayey sandstone, and silty sandstone sediments of the Monterey Formation were encountered at depths of up to 51.5 feet.
51 According to The Nat online fossil locality database and the NHM collections (which are available online through the iDigBio), there are no recorded fossil localities within the project site.52,53 There are 23 recorded vertebrate fossil localities (4521, 5547, 5752, 6283, 6284, 6286, 6550, 6551, 7541, 7532, 7543, 7544, 7546, 7547, 7548, 7549, 7550, 7551, 7552, 7553, 7554, 7555, and 7755) approximately

1.09 miles northeast of the project site. Additional localities lie within 1 mile southwest of the site.

To address the potential for an unanticipated discovery during construction, implementation of MM GEO-1 would be required. MM GEO-1 would require worker training by a qualified Paleontologist, prior to the start of construction, to inform construction personnel of the potential to encounter fossils 50 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. September 26.
51 Alta California Geotechnical, Inc. 2025. Geotechnical Investigation. 15 Argonaut, City of Aliso Veijo, County of Orange, California. Page 4. September 26.
52 Integrated Digitized Biocollections (iDigBio). 2024. Online records search tool. National Science Foundation. Website:
https://www.idigbio.org/portal/search. Accessed on April 10, 2026. 53 San Diego Natural History Museum (The Nat). 2024. Paleontology Collection Database Results, Pleistocene-age vertebrate localities in Aliso Viejo, CA.
332
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
74 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx and procedures to follow in the event fossils are encountered during construction. Implementation of MM GEO-1 would reduce the potentially significant impact to less than significant. The impact would be less than significant with mitigation incorporated.

Conditions of Approval
COA GEO-1a In accordance with Municipal Code 13.08.170, Soil Engineering and Engineering Geology Reports, a soil engineering and engineering geology report shall be required for grading projects unless otherwise waived by the building official. The reports shall include information appropriate for the site including any information required by the building official. Recommendations included in the reports and approved by the building official shall be incorporated in the grading plans or specifications.

Accordingly, prior to issuance of grading permit, the project applicant shall provide grading plans or specifications that include all recommendations from the proposed project’s September 26, 2025, Geotechnical Investigation prepared by Alta California Geotechnical, Inc., or from the latest geotechnical study for the proposed project.

COA GEO-1b Prior to and during grading, all grading activities adjacent to the existing slopes along the western and northern boundaries of the site shall be observed by a licensed California Geotechnical Engineer or Certified Engineering Geologist, consistent with the requirements of Aliso Viejo Municipal Code Chapter 13.08 (Grading and Excavation Code).

If geologic or geotechnical conditions associated with slope instability are encountered that differ from those described in the approved Geotechnical Investigation prepared by Alta California Geotechnical, Inc. (September 26, 2025), the project Geotechnical Consultant shall evaluate such conditions and prepare supplemental geotechnical recommendations, as necessary, in accordance with the California Building Code and California Geological Survey Special Publication 117A.

Any supplemental recommendations or corrective measures shall be incorporated into the grading or construction plans and shall be subject to review and approval by the City Engineer prior to continuation of grading in the affected area, consistent with the Aliso Viejo Municipal Code.

Mitigation Measures
MM GEO-1 The project applicant shall enlist a qualified Paleontologist (meeting the standards of the Society of Vertebrate Paleontology [SVP]) to prepare a Worker Environmental Awareness Program (WEAP) presentation for construction personnel. It will include information on paleontological resources, laws protecting them, types of fossils that could occur at the project site, and protocol for unanticipated discoveries. In the event that fossils are discovered during construction, excavations within 50 feet of the find shall be temporarily halted or diverted. The contractor shall notify the qualified 333
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 75
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Paleontologist to examine the discovery. The qualified Paleontologist shall document the discovery as needed in accordance with SVP standards, evaluate the potential resource, and assess the significance of the find under the criteria set forth in CEQA Guidelines Section 15064.5. Based on the significance of the find, the qualified Paleontologist shall determine procedures to be followed before construction is allowed to resume at the location of the find. If, in consultation with the qualified Paleontologist, it is determined that avoidance is not feasible, the qualified Paleontologist shall prepare a Paleontological Resources Impact Mitigation Program (PRIMP) to outline salvage and recovery procedures. If deemed necessary by the qualified Paleontologist, the PRIMP shall include construction monitoring requirements as well. The PRIMP shall be submitted to the City for review and approval, and the approved plan shall be implemented.
334
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
76 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.8 Greenhouse Gas Emissions
Would the project:
a) Generate greenhouse gas emissions,
either directly or indirectly, that may
have a significant impact on the
environment?
b) Conflict with any applicable plan, policy,
or regulation adopted for the purpose of
reducing the emissions of greenhouse
gases?
Environmental Evaluation
Setting and Threshold of Significance
The project site is within the SoCAB, which is under the jurisdiction of the South Coast AQMD. In 2008, the South Coast AQMD formed a working group to identify GHG emissions thresholds for land use projects that could be used by local lead agencies in the SoCAB. The working group developed several different options, which are contained in the South Coast AQMD Draft Guidance Document– Interim CEQA GHG Significance Threshold (Interim GHG Thresholds). The working group has not provided additional guidance since the release of the interim guidance in 2008. In 2010, the South Coast AQMD Tier 3 threshold was expanded to include non-industrial projects, as explained in the minutes from the most recent working group meeting.54 The South Coast AQMD Board has not approved the thresholds; however, the Guidance Document provides substantial evidence supporting the approaches to significance of GHG emissions that can be considered by the lead agency in adopting its own threshold.

In summary, the South Coast AQMD’s draft threshold uses the Executive Order S-3-05 goal as the basis for the Tier 3 screening level. Achieving the Executive Order’s objective would contribute to worldwide efforts to cap CO2 concentrations at 450 parts per million (ppm) and stabilize global climate.

To determine whether the proposed project would have a significant impact with respect to the generation of GHG emissions, the appropriate tier for this project is Tier 3, which states that if GHG 54 South Coast Air Quality Management District (South Coast AQMD). 2010. Greenhouse Gas CEQA Threshold Stakeholder Working Group Meeting No. 15. September 28. □ □ □
□ □ □
335
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 77
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx emissions are less than 3,000 metric tons (MT) carbon dioxide equivalent (CO2e) per year, projectlevel and cumulative GHG emissions would be less than significant. However, this threshold was developed to meet the 2020 GHG emissions goals. To be consistent with State goals detailed in SB 32, Executive Order B-30-15, and Executive Order S-3-05 to reduce GHG emissions by 40 percent below 1990 levels by 2030, a scaled screening GHG threshold can be developed for an assumed opening year of 2028. Though the South Coast AQMD has not published a quantified threshold beyond 2020, a threshold of 2,040 MT CO2e per year would be appropriate.55 Therefore, this analysis utilizes 2,040 MT CO2e per year for a quantitative threshold of significance for GHG emissions and ARB’s 2022 Scoping Plan for consistency with an applicable GHG emissions reduction plan.

A project’s incremental contribution to a cumulative impact can be found not to be cumulatively considerable if the project would comply with an approved plan or mitigation program that provides specific requirements to avoid or substantially lessen the cumulative problem within the geographic area of the project.

This analysis includes estimates of GHG emissions associated with project construction and operational activities using CalEEMod Version 2022.1. This model is considered by South Coast AQMD to be an accurate and comprehensive tool for quantifying air quality and GHG impacts from land use projects in California. These estimates have been disclosed to comply with CEQA Guidelines Section 15064.4(a) and to provide evidence that the implementation of the plans, policies, and regulations adopted to reduce GHG emissions would result in actual GHG emissions reduction.

Would the project:
a) Generate greenhouse gas emissions, either directly or indirectly, that may have a significant impact on the environment?
Less than significant impact. Both construction and operational activities have the potential to generate GHG emissions. The following is a discussion of the proposed project’s contribution to GHG emissions during both the construction and operation phases.

Construction Greenhouse Gas Emissions
The proposed project would generate GHG emissions during construction activities, resulting from emission sources such as construction equipment, haul trucks, and construction worker vehicles.

Although these emissions would be temporary and short-term in nature, they could represent a substantial contribution of GHG emissions. Construction emissions were modeled using CalEEMod Version 2022.1. Table 6, below, shows the annual construction GHG emissions. 55 The 2,040 metric tons carbon dioxide equivalent (MT CO2e) per year threshold for opening year 2028 is calculated by reducing the 3,000 MT CO2e per year threshold (developed to meet the 2020 GHG emissions goals) by 40 percent, then interpolating to obtain the scaled GHG emissions threshold for 2028. Based on a starting threshold of 3,000 MT CO2e per year in 2020 and a threshold of 1,800 MT CO2e per year in 2030, the 3,000 MT CO2e per year threshold would be reduced by 120 MT CO2e per year through 2030.
336
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
78 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Table 6: Proposed Project Construction Greenhouse Gas Emissions Construction Year
Total GHG Emissions
(MT CO2e per year)
Project Construction–2027 327
Project Construction–2028 263
Total Construction Emissions 590
Emissions Amortized Over 30 Years1 20
Notes:

GHG = greenhouse gas
MT CO2e = metric tons carbon dioxide equivalent
1 Construction GHG emissions are amortized over the 30-year lifetime of the proposed project.

Source: Appendix A.

As shown above, the proposed project would generate approximately 590 MT CO2e during construction. Over 30 years, the construction GHG emissions would be amortized to approximately 20 MT CO2e per year. Since South Coast AQMD has not established a construction GHG threshold, total construction emissions were amortized over 30 years and included in the emissions inventory to account for the short-term, one-time GHG emissions from the construction phase of the proposed project.

Operational Greenhouse Gas Emissions
Operational, or long-term, emissions are those emissions that occur over the life of a project. Project operations were modeled for the 2028 operational year. To present a conservative estimate of emissions, the baseline for the analysis was assumed to be zero. Because the proposed project would demolish and replace an existing structure, the proposed project’s incremental increase in GHG emissions would be lower than estimated and presented below. Sources for operational GHG emissions are summarized below.

Motor Vehicles: These emissions refer to GHG emissions contained in the exhaust from the cars and other on-road vehicles that would travel to and from the project site. Based on the project-specific trip generation rates presented in the Trip Generation and VMT Assessment Memorandum (Appendix I), the proposed project was estimated to generate 356 daily vehicle trips for the 58-unit proposed project. For the purpose of conservative analysis, the emissions in Table 7, below, do not take credit for the office building’s generated vehicle trips and associated emissions that would be replaced by the proposed project.

Natural Gas: These emissions refer to the GHG emissions that occur when natural gas is burned on the project site. The proposed project buildings would be all-electric and would, therefore, not result in any GHG emissions from natural gas use.
337
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 79
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Indirect Electricity: These emissions refer to those generated by off-site power plants to supply electricity required for the proposed project. Although not included in the modeling and Table 7, below, the proposed project would install PV solar panels, consistent with Title 24, Part 6, of the California Energy Code. The inclusion of solar panels would provide on-site renewable energy that would reduce the proposed project’s consumption of electricity generated at off-site power plants.

Area Sources: These emissions refer to those produced during activities such as landscape maintenance.

Water Transport: These emissions refer to those generated by the electricity required to transport and treat the water to be used on the project site.

Waste: These emissions refer to GHG emissions produced by decomposing waste generated by the proposed project.

Table 7 presents the estimated annual GHG emissions from the proposed project’s operational activities. As shown in Table 7, the proposed project would generate approximately 484 MT CO2e per year after the inclusion of 20 MT CO2e per year from project construction. In addition, with continued implementation of various statewide measures, the proposed project’s operational energy and mobile source emissions would continue to decline in the future.

Table 7: Operational Greenhouse Gas Emissions—Unmitigated GHG Emissions Source GHG Emissions (MT CO2e per year)
Area 1
Energy 67
Mobile (Automobiles) 378
Waste 13
Water 5
Amortized Construction 20
Total Annual Project Emissions 484
Applicable Threshold1 2,040
Exceed Applicable Threshold No
Notes:

MT CO2e = metric tons carbon dioxide equivalent
1 The 2,040 MT CO2e per year threshold for opening year of 2028 is calculated by reducing the 3,000 MT CO2e per year threshold (developed to meet the 2020 GHG emissions goals) by 40 percent, then interpolating to obtain the scaled GHG emissions threshold for 2028.

Source: Appendix A.
338
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
80 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx As shown in Table 7, the proposed project’s GHG emissions would not exceed the applicable threshold of significance. In addition, the emissions shown in Table 7 were estimated without taking any reductions for the existing land uses which generate GHG emissions. The proposed project would replace an existing office building with new residential buildings. The existing office use is currently generating GHG emissions that would no longer occur once the existing structure is demolished. Thus, the proposed project’s net increase in GHG emissions would be even lower than what is shown in Table 7. In summary, construction and operational GHG emissions would result in a less than significant impact on the environment.
b) Conflict with any applicable plan, policy, or regulation adopted for the purpose of reducing the emissions of greenhouse gases?
Less than significant impact.
2022 Scoping Plan Consistency
The 2022 Scoping Plan identifies additional GHG reduction actions and strategies necessary to achieve the AB 1279 target of 85 percent below 1990 levels by 2045. These actions and strategies build upon those identified in the first update to the Scoping Plan (2013) and in the second update to the Scoping Plan (2017). Although a number of these measures are currently established as statewide regulations, some measures have not yet been formally proposed or adopted. It is expected that these measures or similar actions to reduce GHG emissions will be adopted as required to achieve statewide GHG emissions targets. Many of the measures are implemented at the State level and therefore not applicable to the proposed project. However, as it relates to local climate actions, Appendix D of the ARB 2022 Scoping Plan highlights three priority areas for local jurisdictions to focus on when reducing GHGs: (1) transportation electrification; (2) VMT reduction; and (3) building decarbonization. The proposed project would be consistent with and would further the goals of all three priority areas.

Regarding transportation electrification, the proposed project would provide EV charging infrastructure in accordance with CALGreen Section 4.106.4.1. Accordingly, each dwelling unit would be EV capable by installing a raceway to accommodate a future branch circuit for future electric vehicle supply equipment (EVSE) installation. Therefore, the proposed project would be consistent with transportation electrification by having the infrastructure to accommodate the future residents’ EV charging needs.

Regarding VMT reduction, as discussed in Impact 2.17(b), the proposed project meets the Project Type screening criteria and is therefore considered to have a less than significant VMT impact.

Therefore, the proposed project would be consistent with VMT reduction goals.

Regarding building decarbonization, the proposed project would have an all-electric building design and would therefore comply with this goal. Furthermore, the proposed project complies with all relevant Energy Code and CALGreen requirements, which would ensure energy efficiency. Impact

2.6(a) demonstrates that the proposed project will not result in any wasteful, inefficient, or 339
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 81
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx unnecessary energy usage as determined by the analysis required under CEQA Section 21100(b)(3) and Section 15126.2(b) of the CEQA Guidelines.

The proposed project would be consistent with the applicable measures outlined in the 2022 Scoping Plan. Therefore, the proposed project would be consistent with the 2022 ARB Scoping Plan, and potential impacts would be less than significant.

Mitigation Measures
None required.
340
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
82 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.9 Hazards and Hazardous Materials
Would the project:
a) Create a significant hazard to the public
or the environment through the routine
transport, use, or disposal of hazardous
materials?
b) Create a significant hazard to the public
or the environment through reasonably
foreseeable upset and accident
conditions involving the release of
hazardous materials into the
environment?
c) Emit hazardous emissions or handle
hazardous or acutely hazardous
materials, substances, or waste within
one-quarter mile of an existing or
proposed school?
d) Be located on a site which is included
on a list of hazardous materials sites
compiled pursuant to Government Code
Section 65962.5 and, as a result, would
it create a significant hazard to the
public or the environment?
e) For a project located within an airport
land use plan or, where such a plan has
not been adopted, within two miles of a
public airport or public use airport,
would the project result in a safety
hazard or excessive noise for people
residing or working in the project area?
f) Impair implementation of or physically
interfere with an adopted emergency
response plan or emergency evacuation
plan?
□ □ □
□ □ □
□ □ □
□ □ □
□ □ □
□ □ □
341
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 83
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact
g) Expose people or structures, either
directly or indirectly to a significant risk
of loss, injury or death involving wildland
fires?
Environmental Evaluation
Setting
The analysis in this section is based, in part, on the Phase I and Phase II Environmental Site Assessments (ESAs) prepared by Stantec Consulting Services, Inc. (Stantec) on July 14, 2025, 56 and
September 4, 2025.
57 Both the Phase I ESA and the Phase II ESA are included in Appendix E of this document.

Based on historical maps and aerial photographs reviewed by the Phase I ESA, the project site was vacant from at least the 1930s to the 1980s and was commercially developed with the existing structure and parking configuration between 1988 and 1992.

According to the Phase I ESA, the following Recognized Environmental Condition (REC) was identified in connection to the project site:
• A west-adjoining fuel station located at 23022 Aliso Creek Road approximately 163 feet (0.03 mile) west of the project site is listed as a gasoline service station since 1996 that reportedly houses three active underground storage tanks (USTs) installed between 2004 and 2016. The USTs range from 10,000 to 20,000 gallons in size and contain diesel, regular, and premium unleaded fuel. A minor spill of two gallons of fuel was reported in 2018 due to a vehicle overfill onto concrete. The spill was cleaned by on-site personnel. The site received permit-related violations between 2014 and 2016 that were returned to compliance. No releases are reported at the site.
56 Stantec Consulting Services, Inc. (Stantec). 2025. Phase I Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. July 14.
57 Stantec Consulting Services, Inc. (Stantec). 2025. Phase II Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. September 4.
□ □ □
342
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
84 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Given the proximity of this fuel station to the project site, the lack of documented assessment of soil, soil vapor, or groundwater at the site, and inferred groundwater flow to the east, this site represents a potential Vapor Encroachment Condition (VEC) and is considered a REC.

Accordingly, to evaluate the REC identified above, Stantec performed a Phase II ESA to evaluate subsurface conditions at the project site. Soils encountered during the Phase II ESA indicated that no VOCs were detected above their respective laboratory reporting limits. Therefore, it was concluded that the west-adjoining fuel station would not represent a potential VEC to the project site, and no further assessment was warranted.

The Phase I ESA also noted that, given the age of the existing building on-site, which was constructed in the 1980s, asbestos-containing materials (ACMs) and lead-based paint (LBP) may be present in the building materials. The Phase I ESA also noted that the existing asphalt parking lot may contain Petromat, a stress-absorbing fabric often associated with asphalt that may contain asbestos.

Would the project:
a) Create a significant hazard to the public or the environment through the routine transport, use, or disposal of hazardous materials?
Less than significant impact. Construction of the proposed project would include the routine transport, use, and disposal of limited quantities of hazardous materials necessary for construction, including fuel and solvents. The use of these hazardous materials would be typical of construction projects, would be short-term, and would be handled in accordance with standard construction practices, as well as with applicable federal, State, and local regulations. Standard construction practices would be observed such that hazardous materials are appropriately contained and remediated as needed, as required by local, State, and federal law. Regulatory requirements would include California Code of Regulations Title 22, Division 4.5, for appropriate management of hazardous materials, as well as the requirements of the EPA, Resource Conservation and Recovery Act (RCRA), California Department of Toxic Substance Control (DTSC), Division of Occupational Safety and Health (Cal/OSHA), Caltrans, and South Coast AQMD.

The proposed project would include residential development, which does not typically use or store large quantities of hazardous materials. During the operational phase of the proposed project, hazardous materials may be handled on the project site. Hazardous materials used during operation would likely be limited to fertilizers, herbicides, pesticides, solvents, household cleaning agents, and similar materials used for maintenance and operation of the townhomes, building facilities, amenities, and landscaping. These types of materials are common and represent a low risk to people and the environment when used as intended. The proposed project would also be required to adhere to State and federal regulatory requirements as discussed above. Therefore, impacts associated with hazardous materials would be less than significant.
343
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 85
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx b) Create a significant hazard to the public or the environment through reasonably foreseeable upset and accident conditions involving the release of hazardous materials into the environment?
Less than significant impact with mitigation incorporated. As discussed above, the Phase I ESA determined that the project site was undeveloped until the construction of a road traversing the project site in 1963 and the construction of the existing office building and parking lot by 1989.

Although the Phase I ESA recognized the west-adjoining fuel station located west of the project site as a potential VEC and REC,
58 the Phase II ESA did not detect any VOCs above their respective laboratory reporting limits, and it was concluded that the fuel station would not pose a potential VEC.59 The Phase I ESA identified the potential for the existing building to contain ACM and LBP and the potential for the existing asphalt parking lot to contain Petromat. 60 As described above, Petromat
may contain asbestos. To minimize the potential for exposure to asbestos and lead during construction activities, the proposed project would implement MM HAZ-1, requiring that all applicable surveys be conducted prior to site development activities in accordance with all applicable local, regional, State, and federal guidelines. If ACMs, LBP, or Petromat are identified, proper removal and disposal procedures, in accordance with all applicable local, regional, State, and federal regulations, would be required.

In addition, as previously discussed above under Impact 2.9(a), the proposed project would be required to comply with all applicable local, State, and federal laws and regulations pertaining to the transport, use, disposal, handling, and storage of hazardous waste during the construction phase to reduce the likelihood and severity of accidents during transit. Proper handling of the use and disposal of hazardous materials associated with residential uses would reduce the potential for exposure.

Therefore, impacts related to construction would be less than significant with mitigation incorporated.

Operation of the proposed project would not involve the transport, use, or disposal of large quantities of hazardous materials. The use of hazardous materials on the project site post-construction would consist of those commonly used in a residential setting for routine maintenance and cleaning and would not be of a significant quantity to create a reasonably foreseeable upset or accident. As such, the proposed project would not introduce uses to the site that would create a significant hazard to the public or the environment through reasonably foreseeable upset or accident conditions involving the release of hazardous materials into the environment. The proposed project would be required to comply with additional regulatory requirements, including but not limited to the Code of Federal Regulations, Title 49, Transportation, specific to the transport of hazardous materials; California Code of Regulations Titles 8, 22, and 26, and their enabling legislation set forth in California Health and Safety Code Division 20, Chapter 6.95, Hazardous Materials Release Response Plans and Inventory; 58 Stantec Consulting Services, Inc. (Stantec). 2025. Phase I Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. July 14.
59 Stantec Consulting Services, Inc. (Stantec). 2025. Phase II Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. September 4.
60 Stantec Consulting Services, Inc. (Stantec). 2025. Phase I Environmental Site Assessment Report. 15 Argonaut Aliso Viejo, California 92656. July 14.
344
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
86 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx and the requirements of the Orange County Health Care Agency Environmental Health Division (i.e., the Certified Unified Program Agency [CUPA]), which would ensure safety standards related to the use and storage of hazardous materials are implemented. Consistency with local, State, and federal regulations related to the transport, storage, use, and disposal of hazardous materials would minimize the potential for upset and accident conditions to occur within the site. Therefore, impacts related to operations would be less than significant, and no mitigation would be required.

In conclusion, the overall project impact would be less than significant with mitigation incorporated. c) Emit hazardous emissions or handle hazardous or acutely hazardous materials, substances, or waste within one-quarter mile of an existing or proposed school? No impact. There are no schools within 0.25 mile of the project site. The nearest schools are Don Juan Avila Middle and Elementary School (26278 Wood Canyon Drive), 0.89 mile southwest of the project site; Aliso Viejo Middle School (111 Park Avenue), 1.15 miles southeast of the project site; and Laguna Hills High School (25401 Paseo De Valencia), 1.18 miles northeast of the project site. As discussed in Impact 2.9(a), construction of the proposed project would include the limited use of hazardous materials, such as fuel and solvents. The use of these hazardous materials would be in compliance with all applicable local, State, and federal regulations. During operation of the proposed project, limited use of hazardous materials would likely be used for building maintenance. Similarly, these hazardous materials would be stored, handled, and disposed of in accordance with applicable regulations. Thus, the proposed project would not include any uses that could potentially generate hazardous materials in significant quantities that would have an impact to surrounding schools.

Therefore, there would be no impact.
d) Be located on a site which is included on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5 and, as a result, would it create a significant hazard to the public or the environment? No impact. Government Code Section 65962.5 refers to the Hazardous Waste and Substance Site List, commonly known as the Cortese List. The Cortese List contains hazardous waste and substance sites with known USTs having a reportable release and solid waste disposal facilities for which there is a known migration. The Cortese List also includes hazardous substance sites selected for remedial action; historic Cortese sites; and sites with known toxic materials identified through the abandoned site assessment program. The proposed project site is not located on a site which is included on a hazardous materials site list compiled pursuant to California Government Code Section 65962.5.61 The closest site recognized by the Cortese List is a closed Leaking Underground Storage Tank (LUST) site, United Parcel Service (T0605902532), located approximately 500 feet southwest of the project site across intervening development at 22 Brookline in Aliso Viejo.62 According to the 61 California Environmental Protection Agency (Cal/EPA). 2026. Cortese List Data Resources. Website:
https://calepa.ca.gov/SiteCleanup/CorteseList/. Accessed April 10, 2026. 62 California State Water Resources Control Board (State Water Board). 2026. GeoTracker. Website:
https://geotracker.waterboards.ca.gov/map/?CMD=runreport&myaddress=15+ARgonaut+Aliso+Viejo. Accessed April 10, 2026.
345
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 87
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Geotracker website, the site has been closed since 1996.63 The closest active site recognized by the Cortese List is located approximately 1.98 miles northeast of the project site and is an active Cleanup Program site located at 24312–24422 Rockfield Boulevard in Lake Forest.64 None of the activities occurring at this site would be close enough to the project site to have an impact. Therefore, the proposed project would not create a significant hazard to the public or the environment. No impact would occur, and no mitigation is required.
e) For a project located within an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project result in a safety hazard or excessive noise for people residing or working in the project area?
No impact. The project site is not within 2 miles of an airport. The nearest airport is John Wayne Airport, located 9.58 miles northwest of the project site. The project site is not within the Airport Influence Area of this airport and is not located within an airport land use plan. Therefore, the proposed project would not result in a safety hazard of excessive noise for people working or living at the project site. No impact would occur.
f) Impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation plan?
Less than significant impact. The City has developed an Emergency Operations Plan (EOP), consistent with the Standardized Emergency Management System (SEMS), outlining the City’s response to extraordinary emergency situations associated with natural disasters, technological incidents, and national security emergencies.65 The EOP is designed to incorporate and coordinate all the facilities and personnel of the City into an efficient organization capable of reacting adequately in the face of any disaster and to conduct such operations as the nature of the disaster deems necessary. It serves as an extension of the California Emergency Plan and the Emergency Resource Management Plan. The EOP is not intended to address normal day-to-day emergencies or the wellestablished and routine procedures used in coping with such emergencies. Instead, the operational concepts reflected in the EOP focus on potential large-scale disasters that can generate unique situations requiring unusual emergency responses. The EOP provides comprehensive policy and guidance for emergency and response operations and details the responsibilities of residents, organizations, and City departments. The EOP also establishes evacuation routes and identifies emergency shelter facilities and water supplies.
63 California State Water Resources Control Board (State Water Board). 2026. GeoTracker. United Parcel Service (T0605902532). Website: https://geotracker.waterboards.ca.gov/profile_report.asp?global_id=T0605902532. Accessed April 10, 2026.
64 California Department of Toxic Substances Control (DTSC). 2024. EnviroStor Hazardous Waste and Substances List.

Website: https:// www.envirostor.dtsc.ca.gov/public/map/?myaddress=Aliso+Viejo. Accessed April 10, 2026. 65 City of Aliso Viejo. 2004. General Plan. Safety Element, 11–12. Website:
https://avcity.org/DocumentCenter/View/395/Safety-Element-PDF. Accessed April 10, 2026. 346
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
88 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx General Plan Figure S-1, Safety Policy Map, identifies evacuation routes in the City.66 Within the vicinity of the project site, Aliso Creek Road and Glenwood Drive are identified as primary evacuation routes.

The project site is within Zone 20 of Aliso Viejo’s Evacuation Zones.67 Designated evacuation routes within Zone 20 include Glenwood Drive, Aliso Creek Road, Aliso Viejo Parkway, and Moulton Parkway. The project site is adjacent to both Glenwood Drive and Aliso Creek Road, and construction would not require closure or partial closure of Glenwood Drive or Aliso Creek Road. The proposed project would be constructed completely within the project site and construction equipment would access the project site via Argonaut, which is the main access point to the project site. If any road closures to Argonaut are required, the project applicant and construction crew would be required to coordinate with the City of Aliso Viejo Public Works Department to ensure that emergency access routes are maintained during construction. Thus, construction of the proposed project would not impede the use of surrounding roadways for emergencies or access for emergency response vehicles.

Operation of the proposed project would be designed to not interfere with surrounding roadways, and the proposed project would provide adequate emergency vehicle access consistent with City and the Orange County Fire Authority (OCFA) requirements for emergency access.

Furthermore, the project site is not identified as a Constrained Access Parcel or as a parcel which may be vulnerable in the event of an evacuation due to a lack of redundant access, in General Plan Safety Element Figure 8, Impaired Access Roads and Parcels in Aliso Viejo. 68 Therefore, the proposed project would not result in adverse impacts on emergency evacuation routes that have not been previously identified in the City’s General Plan and accounted for in the City’s EOP.69 Therefore, the proposed project would not result in significant impacts to emergency access during construction or operation. The proposed project would not impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation plan. Impacts would be less than significant.
g) Expose people or structures, either directly or indirectly, to a significant risk of loss, injury or death involving wildland fires?
Less than significant impact. California Department of Forestry and Fire Protection (CAL FIRE) has mapped fire threat potential throughout California and ranks fire threats within a designated Fire 66 City of Aliso Viejo. 2004. General Plan. Safety Element, Figure S-1 Safety Policy Map. Website: https:// avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 10, 2026. 67 City of Aliso Viejo. 2024. Citywide Evacuation Zones. Website: https://avcity.org/DocumentCenter/View/3750. Accessed April 10, 2026.
68 City of Aliso Viejo. 2004. General Plan. Safety Element. Website:
https://adecinnovations.sharepoint.com/sites/ESSite/Shared%20Documents/ES/Active%20Projects/6513%20Brandywine %20Homes/0001%2015%20Argonaut/BACKGROUND/Reference%20Library/_General%20Plan_/Elements/gp_safety.p df?CT=1778625769333&OR=ItemsView. Accessed May 12, 2026. 69 Ibid.
347
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 89
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Hazard Severity Zone (FHSZ) on a scale of moderate, high, and very high fire severity. According to the most recent CAL FIRE Hazards Severity Zone maps, the project site is not located within a designated FHSZ.70 The project site is located within an urbanized area and is surrounded by intervening development. According to the General Plan, the project site is not located along an urban wildfire interface (WUI) and is not located in the portions of the City abutting the Aliso and Wood Canyon Wilderness Park, located approximately 0.82 mile west of the project site within OCFA’s Very High Fire Hazard Severity Zone (VHFHSZ), where wildfires are of the greatest risk.71 Additionally, the project site and its surrounding areas do not have a history of wildfire.72 The nearest natural and native hazardous vegetation is located approximately 0.62 mile northwest on Aliso Creek Road and Westwing and approximately 0.75 mile southeast on Aliso Viejo Parkway and Moulton Parkway. Wildfires in either area could carry embers to the project site. Additionally, humancaused vegetation fire could be ignited within the existing screening trees along the western and northern perimeters of the project site. However, the proposed project would be required to comply with the 2025 California Fire Code, as amended, in accordance with Municipal Code Chapter 13.04, and would be subject to approval by OCFA. Adherence with fire code standards and approval by OCFA would reduce the potential impacts associated with the possibility of an off-site wildfire showering embers into the site given the incorporation of ignition-resistant construction along with fire protection features that would be provided for the proposed buildings.

Further, the project site is in a developed, built-up urban area that is not adjacent to any VHFHSZ or areas in the WUI. Therefore, the proposed project would not expose people or structures to wildland fire hazards. Impacts would be less than significant.

Mitigation Measures
MM HAZ-1 Implementation of Asbestos-containing Material, Lead-based Paint, and Petromat Surveys Prior to Site Demolition Activities
Prior to the issuance of demolition permits, the proposed project shall retain a Qualified Environmental Professional to conduct asbestos-containing material (ACM), lead-based paint (LBP), and Petromat surveys. If ACM or LBP are identified in existing building materials or if asbestos is identified within any Petromat that is part of the existing parking lot, proper removal and disposal of the materials in 70 California Department of Forestry and Fire Protection (CAL FIRE). 2026. Fire Hazard Severity Zones. Website:
https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones.

Accessed April 10, 2026.
71 California Department of Forestry and Fire Protection (CAL FIRE). 2026. Fire Hazard Severity Zones. Website:
https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones.

Accessed April 10, 2026.
72 California Department of Forestry and Fire Protection (CAL FIRE). 2024. California Wildfire History Map. Website: https:// projects.capradio.org/california-fire-history/#10.64/33.5901/-117.7005. Accessed April 10, 2026. 348
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
90 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx accordance with applicable local, regional, State, and federal regulations would be required. In addition, the developer shall implement all appropriate engineering controls, work practices, and notification procedures to prevent exposure of workers and the public and shall prepare and submit all necessary compliance documentation to the City.
349
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 91
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.10 Hydrology and Water Quality
Would the project:
a) Violate any water quality standards or
waste discharge requirements or
otherwise substantially degrade surface
or groundwater quality?
b) Substantially decrease groundwater
supplies or interfere substantially with
groundwater recharge such that the
project may impede sustainable
groundwater management of the basin?
c) Substantially alter the existing drainage
pattern of the site or area, including
through the alteration of the course of a
stream or river or through the addition
of impervious surfaces, in a manner
which would:
(i) result in substantial erosion or
siltation on- or off-site;
(ii) substantially increase the rate or
amount of surface runoff in a
manner which would result in
flooding on- or off-site;
(iii)create or contribute runoff water
which would exceed the capacity of
existing or planned stormwater
drainage systems or provide
substantial additional sources of
polluted runoff; or
(iv) impede or redirect flood flows?
d) In flood hazard, tsunami, or seiche
zones, risk release of pollutants due to
project inundation?
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
350
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
92 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact
e) Conflict with or obstruct implementation
of a water quality control plan or
sustainable groundwater management
plan?
Environmental Evaluation
Setting
This analysis is based in part on the Drainage Report and the Water Quality Management Plan (WQMP) prepared for the proposed project by Advanced Civil Group, Inc., on April 7, 2026 and revised on July 14 and July 8, 2026, respectively.
73,74
The project site is located within the Aliso Creek Watershed. Site drainage is generally broken up into four drainage areas under existing conditions, where drainage is collected via V-ditches adjacent to the site’s northern and western boundaries that eventually drain into existing underground utility pipes in Argonaut.

The project site is approximately 62 percent impervious, with vegetated sloped areas located primarily along the northern and western perimeters. The proposed project would slightly increase the project site to 65 percent impervious.
75 Apart from minor landscape drains that outlet to the parking lot curb face, there are no known underground storm drain facilities on-site.

According to the General Plan’s Safety Element, the project site is not within a designated 100-year flood zone, and Federal Emergency Management Agency’s (FEMA’s) National Flood Hazard Layer shows the project site within an area of minimal flood hazard (Zone X).76,77 Would the project:
73 Advanced Civil Group, Inc. 2026. Drainage Report: Tract No. 19489. Proposed 58-unit Townhome Development Aliso Viejo, California. July 14.
74 Advanced Civil Group, Inc. 2026. Water Quality Management Plan (WQMP). July 8. 75 X Engineering & Consulting. 2024. Water Quality Management Plan (WQMP), 95 Argonaut. September. 76 City of Aliso Viejo. General Plan. Safety Element, Figure S-1, Safety Policy Map. Website: https:// avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 10, 2026. 77 Federal Emergency Management Agency (FEMA). 2024 National Flood Hazard Layer (web viewer). Website: https:// hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd. Accessed April 10, 2026.
□ □ □
351
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 93
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx a) Violate any water quality standards or waste discharge requirements or otherwise substantially degrade surface or groundwater quality?
Less than significant impact. Project impacts related to water quality could occur over three different periods:
• During the demolition, earthwork, and construction phase, where the potential for erosion, siltation, and sedimentation would be the greatest;
• Following construction, before the establishment of ground cover, when the erosion potential may remain relatively high; and
• After project completion, when impacts related to sedimentation would decrease markedly but those associated with urban runoff would increase.

Polluted runoff can have harmful effects on drinking water, recreational water, and wildlife. Urban runoff pollution includes a wide array of environmental and stormwater characteristics depending onsite conditions (e.g., land use, impervious cover, and pollution prevention practices), rain events (duration, amount of rainfall, intensity, and time between events), soil type and particle sizes, the amount of vehicular traffic, and atmospheric deposition. Major pollutants typically found in runoff from urban areas include sediments, nutrients, oxygen-demanding substances, heavy metals, petroleum hydrocarbons, pathogens, and bacteria. Most urban stormwater discharges are nonpoint sources.

The City is within the jurisdictional area of the San Diego RWQCB.78 The San Diego RWQCB requirements are further clarified by the Orange County Drainage Area Management Plan (DAMP), which requires the preparation and implementation of WQMPs for development projects.79 The DAMP reduces the pollution content of stormwater to the Maximum Extent Practicable (MEP). The purpose of the Orange County DAMP is to satisfy NPDES permit conditions for creating and implementing a Storm Water Management Plan (SWMP) to reduce pollutant discharges to the MEP. The DAMP contains guidelines on structural and nonstructural BMPs for meeting the NPDES goals.

Additionally, the City participates in the South Orange County Water Quality Improvement Plan (WQIP), a watershed-based planning framework developed to improve surface water quality through the reduction of pollutant loads in urban stormwater runoff within south Orange County. The WQIP identifies priority water quality conditions and implementation strategies intended to protect receiving waters and support compliance with applicable NPDES permit requirements.80 Consistent with the goals of the WQIP, the proposed project would be required to incorporate site design features, source 78 California State Water Resources Control Board (State Water Board). 2026. State and Regional Water Boards. Website:
https://www.waterboards.ca.gov/waterboards_map.html. Accessed April 10, 2026. 79 County of Orange Department of Public Works. 2026. OC Environmental Resources, 2003 Drainage Area Management Plan. Website: https://ocerws.ocpublicworks.com/service-areas/oc-environmental-resources/regional-stormwaterprogram/background-damp. Accessed April 10, 2026. 80 San Diego Regional Water Quality Control Board. South Orange Watershed Management Area Water Quality Improvement Plan. Website: https://ocgov.app.box.com/v/SOCWMAWQIPv1-6Main. Accessed July 17, 2026. 352
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
94 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx control measures, and treatment control BMPs to minimize pollutants in runoff and manage postconstruction stormwater discharges.

Consistent with the DAMP and City requirements, the project applicant would be required to prepare and submit a Preliminary Project WQMP, a Hydrology Report, and a SWPPP prior to project grading and construction. Compliance with these requirements would ensure that stormwater runoff generated by the proposed project is appropriately treated and managed in accordance with applicable local, regional, and state stormwater regulations.

As described in the proposed project’s Drainage Report (Appendix F), existing drainage on the project site originates from overland flow from sloped landscaping and roof runoff that flows south, east, and west into V-ditches along the northern and western boundaries of the project site. 81 Peak
flows under the proposed project within the sloped areas would be maintained as overland flow and flow east, west, and south along the boundaries of the site’s developed footprint, where they would eventually be conveyed into underground utility pipes prior to draining into Argonaut’s existing stormwater infrastructure located at the southeastern corner of the site.

In the post-construction condition, runoff generated from the developed portions of the project site, including rooftops, drive aisles, parking areas, walkways, private yards, common landscaped areas, and other hardscape surfaces, would be collected through a network of area drains and storm drain facilities and conveyed to the proposed project's water quality treatment system. The proposed project would incorporate a modular wetland/biofiltration treatment system designed to provide low impact development (LID) treatment of urban runoff prior to discharge. The treatment system would include pretreatment and biofiltration components that remove pollutants from stormwater runoff before treated flows are conveyed to the discharge system. Runoff from the treated drainage management area, which encompasses the proposed developed footprint, would be directed through the biofiltration facility and subsequently pumped to the existing storm drain system within Argonaut.

In addition to water quality treatment features, the proposed project would incorporate hydromodification management measures to control post-project peak runoff rates. The proposed project is located within a Hydromodification Zone82 and includes an underground storage chamber to attenuate stormwater flows and mitigate increases in peak discharge rates. According to the project's WQMP, the proposed residential development would not generate greater runoff than the existing developed condition and would not discharge runoff at rates exceeding applicable hydromodification thresholds. Accordingly, the proposed project would satisfy hydromodification control requirements while also providing treatment of stormwater runoff through the biofiltration and modular wetland systems prior to discharge to Argonaut.

As the proposed project would disturb more than 1 acre of land, it would be subject to the NPDES General Permit for Stormwater Discharges Associated with Construction and Land Disturbance 81 Advanced Civil Group, Inc. 2026. Drainage Report: Tract No. 19489. Proposed 58-unit Townhome Development Aliso Viejo, California. July 14.
82 Advanced Civil Group, Inc. 2026. Water Quality Management Plan (WQMP). July 8. 353
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 95
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Activities Construction General Permit (Construction General Permit). Construction activity subject to the Construction General Permit includes any construction or demolition activity, including but not limited to clearing, grading, grubbing, excavation, or any other activity that results in a land disturbance of equal to or greater than 1 acre. The Construction General Permit requires development and implementation of a SWPPP and monitoring plan, which must include erosion and sediment control BMPs that would meet or exceed measures required by the Construction General Permit to control potential construction-related pollutants. Erosion-control BMPs prevent erosion, whereas sediment controls trap sediment once it has been mobilized. The types of required BMPs are relative to the amount of soil disturbed, the types of pollutants used or stored at the project site, and proximity to water bodies.

The WQMP prepared for the proposed project is intended to comply with the requirements of the County of Orange NPDES Stormwater Program. The WQMP outlines the operation and maintenance of all BMPs to be used at the project site, including a catch basin storm filter, hydrologic source controls, and structural and nonstructural source controls.

Additionally, project construction activities would be required to comply with applicable City requirements to control erosion and reduce or eliminate stormwater runoff containing sediment, including Municipal Code Chapter 13.08, Article XIII, Erosion Control, which requires preparation of an Erosion Control Plan submitted to the building official and the implementation of erosion and sediment control measures. Project construction activities would also be required to comply with water quality measures included in the City’s Water Quality Ordinance (Municipal Code Chapter 7.35, Stormwater Management). The Water Quality Ordinance is designed to effectively prohibit nonstormwater discharges into the storm sewers, reduce the discharge of pollutants, and achieve compliance with the Clean Water Act and the Porter-Cologne Water Quality Control Act. Specifically, in accordance with Section 7.35.080, Control of Urban Runoff–New Development and Redevelopment Projects, prior to the City’s issuance of a grading or building permit for the proposed project, the project applicant would be required to submit project plans demonstrating compliance with all applicable local ordinances; California Stormwater Quality Association (CASQA) standards; and the City’s water quality manual, which includes the City’s jurisdictional urban runoff management plan or local implementation plan, the Orange County DAMP, and the City’s NPDES permit.

In addition to the requirements of Municipal Code Section 7.35.080, project construction activities would be required to comply with Municipal Code Section 7.35.070, Control of Urban Runoff – Construction Projects, which requires the project applicant to submit a pollution control plan, construction BMP plan, and/or an erosion and sediment control plan meeting the requirements of the water quality manual and to submit evidence of coverage under the Construction General Permit prior to issuance of a permit involving ground-disturbing activities.

Compliance with the above regulations would ensure that impacts related to water quality during construction of the proposed project would be less than significant.

The proposed project would comply with the NPDES requirement through implementation of the Preliminary Project WQMP, and the Orange County DAMP and South Orange County WQIP; as such, 354
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
96 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx construction of the proposed project would not violate water quality standards or degrade surface or groundwater quality.

During operations, the project site would be subject to compliance with the Regional Municipal Separate Storm Sewer System (MS4) permit. The Regional MS4 Permit (Order No. R8-2009-0030, as amended by Order No. R8-2010-0062) requires co-permittees, including the City, to reduce the discharge of pollutants from new development and significant redevelopment to the MEP. All development projects are required to implement source control and site design practices. Per the MS4 Permit requirements for redevelopment, the proposed project will also incorporate LID elements into the site design as well as the implementation of BMPs.

As noted in the WQMP, the project site is located within a Hydromodification Zone. 83 Thus, the
proposed project is required to mitigate the difference between the existing and proposed runoff peak flow rates. The proposed hydromodification management system would be designed to attenuate and manage stormwater flows to mimic pre-development hydrology, per MS4 Permit requirements. As previously mentioned, hillside runoff would be channeled through underground utility pipes and then conveyed to the front of the property, mimicking existing on-site drainage patterns. The impervious surfaces within the development footprint of the project site would increase by 3 percent from 62 percent to 65 percent under the proposed project.
84 For runoff collected from buildings, drive aisles, hardscape, and landscaped areas, stormwater would be collected via area drains and directed to a biofiltration system for treatment before being pumped for final discharge into Argonaut.85 During operations, peak flow levels would be maintained.

Therefore, the proposed project would be consistent with requirements for Hydromodification Zones, as stipulated within the WQMP. The proposed project would be designed to mimic the existing condition to the maximum extent possible and would not negatively impact downstream infrastructure.

The proposed project would be subject to federal, State, and local regulations related to water quality, including the City’s Water Quality Ordinance. Implementation of the measures outlined above, including water quality operational BMPs, would reduce pollutants of concern associated with the stormwater runoff from the project site in compliance with the Regional MS4 Permit and ensure the proposed project would not violate any water quality standards or waste discharge requirements or otherwise substantially degrade surface or ground water quality. The impact would be less than significant.
83 Advanced Civil Group, Inc. 2026. Water Quality Management Plan (WQMP). July 8. 84 Ibid.
85 Ibid.
355
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 97
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx b) Substantially decrease groundwater supplies or interfere substantially with groundwater recharge such that the project may impede sustainable groundwater management of the basin?
Less than significant impact. The project site is located within the boundaries of the MNWD.

MNWD’s potable water supply is entirely imported water purchased from the Municipal Water District of Orange County (MWDOC).
86 As such, project implementation would not substantially decrease groundwater supplies associated with water demand such that the proposed project would impede sustainable groundwater management of the basin.

The proposed project would slightly reduce the pervious surfaces as compared to existing conditions.

Under the existing conditions, the project site is approximately 62 percent impervious and the proposed project would increase the project site to 65 percent impervious. 87 However, as described in
the WQMP, the existing soil type does not allow for adequate infiltration due to existing constraints with the soil conditions. Because the project site does not currently allow for infiltration and groundwater recharge, the proposed project would not interfere substantially with groundwater recharge such that the proposed project could impede sustainable groundwater management of the basin. As such, the proposed project would not interfere with groundwater recharge or impede sustainable groundwater management of a basin. Impacts would be less than significant. c) Substantially alter the existing drainage pattern of the area, including through the alteration of the course of a stream or river or through the addition of impervious surfaces, in a manner which would:
(i) result in substantial erosion or siltation on- or off-site; Less than significant impact. As discussed above, the proposed project would increase impervious surfaces at the project site by approximately 1 percent across the project site as a whole and by approximately 3 percent within the development footprint of the project site. These increases are not considered substantial because the proposed project would be subject to the NPDES permit requirements and would implement BMPs and LID elements to reduce runoff and erosion. The proposed condition peak flow drainage would mimic the existing condition to the maximum extent possible, and the proposed project would install a bioretention basin to address 10-year storm flows.

As previously discussed, the proposed project’s peak flow would either be maintained or reduced below existing conditions across all four drainage areas.

According to the Geotechnical Investigation, the slopes on-site are considered compressible and not suitable to support the proposed structures. Implementation of the recommendations provided in the Geotechnical Investigation in accordance with Municipal Code Section 13.08.070, as discussed in Section 2.7, Geology and Soils, would ensure that runoff is controlled and directed off-site in a 86 Moulton Niguel Water District (MNWD). 2025. 2020 Urban Water Management Plan, 2021. Website:
https://www.mnwd.com/wp-content/uploads/2021/12/2020-Urban-Water-Management-Plan.pdf. Accessed April 10, 2026. 87 Advanced Civil Group, Inc. 2026. Drainage Report: Tract No. 19489. Proposed 58-unit Townhome Development Aliso Viejo, California. July 14.
356
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
98 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx nonerosive manner and that the slopes and natural drainage patterns are maintained over the life of the proposed project. The proposed project would not alter the course of a river or stream as the site is developed and located in an urban and developed area. As such, the proposed project would not alter the existing drainage pattern at the project site in a manner that would result in on- or off-site erosion or siltation. Additionally, the proposed project would implement the provisions provided in the WQMP prepared for the proposed project, which includes ongoing operation and management of BMPs at the project site. Further, the proposed project would be required to adhere to Article XIII of Chapter 13.08 of the City’s Municipal Code, which contains provisions related to erosion control such as grading specifications and erosion control device requirements. Adherence to the WQMP would also ensure compliance with the County NPDES Stormwater Program. As such, impacts would be less than significant.
(ii) substantially increase the rate or amount of surface runoff in a manner which would result in flooding on- or off-site;
Less than significant impact. As discussed above, although the proposed project would increase impervious surfaces on the project site as compared to the existing conditions, BMPs designed to manage stormwater runoff would be implemented to reduce runoff and erosion. The proposed project would not alter the course of a river or stream. Stormwater runoff from buildings, drive aisles, hardscape, and landscaped areas would be routed to a biofiltration system for treatment before final discharge into Argonaut. The proposed project would be consistent with the approved drainage plan provided in the Drainage Report (Appendix F), including the proposed basin discussed above, which would reduce peak flows from the project site and would not result in increased surface runoff in a manner that would result in flooding. Additionally, all proposed habitable structures have been designed and graded such that finished floor elevations are above the adjacent public and private street elevations, providing positive drainage away from the buildings.88 Surface runoff generated by the 100-year storm event will be collected and conveyed through proposed on-site drainage improvements and/or adjacent street conveyance systems in accordance with Orange County Local Drainage Manual requirements. The proposed project’s peak flow drainage would mimic the existing condition to the maximum extent possible. The proposed biofiltration system is designed for hydromodification management as well as peak flow mitigation. Peak flows from all drainage areas on the project site would ultimately discharge into existing stormwater infrastructure in Argonaut located at the southeastern corner of the site. As such, impacts would be less than significant. (iii) create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff; or
Less than significant impact. As discussed above, the proposed project would not substantially alter the existing drainage pattern at the project site through the increase of impervious surfaces at the project site or by altering the course of a river or stream. The proposed project would connect to 88 Advanced Civil Group, Inc. 2026. Drainage Report: Tract No. 19489. Proposed 58-unit Townhome Development Aliso Viejo, California. July 14.
357
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 99
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx existing water and sanitary sewer lines and would include the installation of stormwater management systems on-site. Stormwater from the proposed project would be directed either to area drains and conveyed to a biofiltration system for treatment or to underground utility pipes before ultimately draining into Argonaut. The proposed project has been designed to meet water quality objectives as required by the MS4 Permit. The proposed project would be designed consistent with the approved drainage plan and would not exceed the capacity of the existing stormwater drainage system.

Additionally, the proposed project would implement the provisions provided in the WQMP and the Geotechnical Investigation prepared for the proposed project—which include ongoing operation and management of BMPs at the project site and measures to ensure on-site runoff is controlled and directed off-site in a nonerosive manner. Further, adherence to the WQMP would ensure compliance with the County NPDES Stormwater Program, which would include biofiltration, and modular wetland systems and detention systems to control and reduce the discharge of pollutants in stormwater.

Compliance with the WQMP would address potential additional sources of polluted runoff from the project site. The impact would be less than significant. (iv) impede or redirect flood flows?
Less than significant impact. The project site is within an area of minimal flood hazard (Zone X);89 and the proposed project would be consistent with the approved drainage plan and would not cause flood flows to be impeded or redirected. Any potential flooding on-site would either be funneled into underground utility pipes or into area drains and a proposed biofiltration system for treatment before draining into Argonaut. Peak flows from the site would drain into existing stormwater infrastructure located in Argonaut. As such, the impact would be less than significant. d) In flood hazard, tsunami, or seiche zones, risk release of pollutants due to project inundation?
No impact. The project site is located more than 5 miles inland from the Pacific Ocean and is not situated near a large enclosed body of water; therefore, the site is not subject to inundation from a tsunami or seiche. In addition, the project site is located within an area of minimal flood risk. As such, the potential for flood-, tsunami-, or seiche-related inundation to cause the release of pollutants or hazardous materials into the environment is negligible. As such, no impact would occur. e) Conflict with or obstruct implementation of a water quality control plan or sustainable groundwater management plan?
Less than significant impact. The project site is within the Aliso Creek Watershed and is subject to the Water Quality Control Plan for the San Diego Basin (Basin Plan). The Basin Plan includes an implementation plan describing the actions by the RWQCB and others that are necessary to achieve and maintain the water quality standards as well as water quality goals and policies that govern the 89 Federal Emergency Management Agency (FEMA). 2026. National Flood Hazard Layer (NFHL). Website: https://hazardsfema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd. Accessed May 11, 2026.
358
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
100 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx San Diego Basin.90 The proposed project would comply with the goals and policies outlined in the Basin Plan, such as nonpoint source pollution control, which require the proposed project to employ LID strategies as well as site-specific BMPs and implementation programs, including coordination with local stormwater permits. As previously discussed, the proposed project would comply with the WQMP prepared for it to ensure that the proposed project meets water quality standards and would not degrade surface or groundwater quality. Therefore, the proposed project would not conflict with or obstruct implementation of a water quality control plan. Impacts would be less than significant.

Mitigation Measures
None required.
90 California State Water Resources Control Board (State Water Board). 2024. San Diego Regional Water Quality Control Board (San Diego RWQCB). San Diego Basin Plan. Website:
https://www.waterboards.ca.gov/sandiego/water_issues/programs/basin_plan/. Accessed April 10, 2026. 359
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 101
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.11 Land Use and Planning
Would the project:
a) Physically divide an established
community?
b) Cause a significant environmental
impact due to a conflict with any land
use plan, policy, or regulation adopted
for the purpose of avoiding or mitigating
an environmental effect?
Environmental Evaluation
Setting
The General Plan currently designates the project site as Business Park (Exhibit 3). The proposed project would require a GPA to change the land use designation from Business Park to MDR. The MDR land use designation is intended to provide residential development with a density between 8 and 18 du/acre, with an average density of 12 units per gross acre.91 The project site is currently zoned Business Park-2 (Exhibit 4). The proposed project requests a rezone to change the zoning designation from Business Park-2 to RM. The RM zoning district is intended to provide for the development and preservation of medium density neighborhoods containing detached and attached single-family homes on smaller lots, duplexes, townhomes, apartments, and condominiums (Municipal Code Chapter 15.10).

Would the project:
a) Physically divide an established community?
No impact. The project site is in a highly developed and urbanized area and is currently developed with an office building and parking lot. The surrounding area contains office, commercial, and residential uses. Land adjacent to the proposed project is designated for Very Low Density Residential to the north, Business Park to the south and east, and Neighborhood Commercial to the west. The project site is not large enough or otherwise configured in such a way that would create a physical barrier within an established community. A typical example of such a barrier would be a 91 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element. Website:
https://avcity.org/DocumentCenter/View/391/Land-Use-Element-PDF. Accessed April 10, 2026. □
□
□
□
□
□
360
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
102 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx project that involved a continuous right-of-way, such as a roadway, which would divide a community and impede access between parts of the community. The proposed project does not include these types of features. Implementation of the proposed project would not disrupt the surrounding land uses or divide the physical arrangement of the established communities adjacent to the project site.

Therefore, the proposed project would not physically divide an established community. No impact would occur, and no mitigation is required.
b) Cause a significant environmental impact due to a conflict with any land use plan, policy, or regulation adopted for the purpose of avoiding or mitigating an environmental effect?
Less than significant impact. The proposed project would include a GPA to amend the General Plan land use designation from Business Park to MDR and a rezone to change the zoning from Business Park-2 to RM. The land uses to the north, south, east, and west of the project site are designated by the General Plan as Very Low Density Residential, Business Park, and Neighborhood Commercial. The proposed GPA would be consistent with the existing surrounding land uses, and with the approval of these changes, the proposed project would not conflict with any applicable land use plan, policy, or regulation adopted for the purposes of avoiding or mitigating an environmental effect. Table 8 shows an analysis of the proposed project’s consistency with relevant policies of the Aliso Viejo General Plan adopted for the purpose of avoiding or mitigating an environmental effect. As shown in Table 8, the proposed project is consistent with all applicable General Plan policies.

Table 8: Project Consistency with Applicable General Plan Policies Aliso Viejo General Plan Policies and Actions Project Consistency Land Use Element
Policy LU-2.1: Preserve the current pattern of
development that encourages more intense and higher
density development at the core of the community
(near Grand Park and Aliso Viejo Town Center) and
less intense uses radiating from the central core.

Consistent. The proposed project includes
redevelopment of an underutilized office space that is
not within the City’s central core. The proposed project would include 58 townhome units, which is consistent
with the homes located just north of the site on
Glenwood Drive. Therefore, the proposed project
would provide an appropriate density, consistent with
this policy.

Policy LU-2.4: Encourage land uses that complement
(in type, size, scale and design) the community’s
topography, scenic vistas, and natural resources.

Consistent. The proposed project includes a
townhome development in an area that is developed
and urbanized. Redevelopment of the site would be
generally consistent with existing surrounding uses,
including the existing homes north of the site. Further, as discussed in Section 2.1, Aesthetics, the proposed
project would not damage a scenic vista or natural
resources. As such, the proposed project is consistent
with this policy.
361
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 103
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency Policy LU-4.1: Encourage environmentally sensitive
development patterns, promote public education, and
enforce infrastructure criteria that protect residents and property from hazards related to slope stability and
flooding.

Consistent. The proposed project consists of multifamily residential redevelopment in an urbanized area and would not degrade environmentally sensitive
areas of the City. As discussed in Section 2.15, Public Services, the proposed project would pay all required
and applicable school district impact fees. The
proposed project is not located within or near a flood
zone. Consistent with the requirements of the
Municipal Code, the proposed project would comply
with all recommendations in the project-specific
Geotechnical Investigation, as detailed in COA GEO1a and COA GEO-1b related to slope stability. On-site drainage and water quality improvements would
provide protection from localized flooding through
implementation of the approved drainage plan for the
proposed project, which would reduce peak flows from
the project site. As such, the proposed project is
consistent with this policy.

Policy LU-4.2: In areas where residential and
business park or office land uses abut each other, use
buffering techniques employing water-conserving
landscaping, setbacks, screening, and appearance
standards to improve compatibility.

Consistent. The proposed project would be buffered
from adjacent business park uses by setbacks and
landscaping, including a 20-foot setback within sloped
landscaped areas of the project site. In addition, the
proposed project would include landscaping that
includes native and/or low water plants designed to
support water conservation. The existing screening
trees on the project site would remain.

Policy LU-4.4: Reduce the discharge of pollutants and
runoff flow from urban development to the maximum
extent practicable.

Consistent. As discussed in Section 2.10, Hydrology
and Water Quality, the proposed project includes an
on-site biofiltration system designed to treat runoff
before discharging into Argonaut. The proposed water
quality BMPs would adhere to WQMP requirements,
including providing operational BMPs that would
reduce pollutants of concern associated with the
stormwater runoff from the project site in compliance
with the Regional Municipal Separate Storm Sewer
System (MS4) Permit and ensure the proposed project
would not violate any water quality standards or waste
discharge requirements or otherwise substantially
degrade surface or ground water quality. As such, the
proposed project is consistent with this policy.

Policy LU-5.3: Ensure that new development is
consistent with City and service provider plans to
complete needed improvements and funding capacity
for such improvements.

Consistent. As discussed in Section 2.15, Public
Services and Section 2.19, Utilities and Service
Systems, existing public and utility services are
adequate to serve the proposed project. Any
362
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
104 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency improvements would be constructed in compliance
with City and service provider standards and the
project applicant would pay all applicable fees as
required. As such, the proposed project is consistent
with this policy.

Policy LU-8.2: Require recycling, composting, source
reduction and education efforts throughout the
community, including residential, businesses,
industries, and institutions, within the construction
industry, and in all City-sponsored activities.

Consistent. As discussed in Section 2.19, Utilities and Service Systems, the proposed project would be
required to comply with applicable federal, State, and
local regulations regarding the recycling, composting,
source reduction, and education efforts. As such, the
proposed project is consistent with this policy.

Policy LU-11.1: Ensure that new development
contributes its fair share to the timely construction of new school facilities, to the extent permitted by law,
and compatible with other City land use objectives.

Consistent. As discussed in Section 2.15, Public
Services, the project applicant would be required to
pay all statutory fees in place at the time in compliance with Senate Bill (SB) 50 and demonstrate proof of
payment to the City for approval of a building permit.

Payment of developer fees under SB 50 would ensure
school related impacts are less than significant. As
such, the proposed project is consistent with this
policy.

Policy LU-12.2: As a condition upon new
development, require payment of park fees and/or
dedication and provision of parkland, recreation
facilities and/or multiuse trails that improve the public and private recreation system.

Consistent. As discussed in Section 2.15, Public
Services, the project applicant would be required to
pay all public benefits fees in accordance with the
Municipal Code Chapter 14.16, which would satisfy the
City’s parkland requirement. The proposed project
would also provide 17,214 square feet of common
usable open space and on-site amenities to residents
that would partially offset impacts to parks facilities. As such, the proposed project is consistent with this
policy.

Conservation/Open Space Element
Policy COS-1.2: Reduce the amount of water used for
landscaping and increase use of native and low water
plants. Maximize use of native, low water plants for
landscaping of areas adjacent to sidewalks or other
impermeable surfaces.

Consistent. The proposed project would be required
to comply with the City’s landscaping requirements,
including Chapter 7.30, Water Efficient Landscape
Regulations, which would increase water efficiency.

The project proposes landscaping that includes native
and/or low water plants. As such, the proposed project
is consistent with this policy.

Policy COS-1.4: Promote water conservation
measures, reduce urban runoff, and prevent
groundwater pollution within development projects,
property maintenance, City operations and all activities requiring City approval.

Consistent. As discussed in Section 2.10, Hydrology
and Water Quality, the proposed project would
implement structural, source control, and site design
BMPs to address water quality conditions associated
with the proposed project consistent with the County of 363
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 105
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency Orange NPDES Stormwater Program through
implementation of the project-specific WQMP. The
proposed project would adhere to WQMP
requirements, which would reduce pollutants of
concern associated with the stormwater runoff from the
project site in compliance with the Regional MS4
Permit and ensure the proposed project would not
violate any water quality standards or waste discharge
requirements or otherwise substantially degrade
surface or ground water quality. As such, the proposed
project is consistent with this policy.

Policy COS-4.2: Encourage and maintain high-quality
architectural and landscaping designs that enhance or
complement the community’s visual character.

Consistent. The proposed project would be designed
with elements such as terra-cotta roof tiles, earth-tone color palettes, and oversized decks to reinforce the
City’s indoor-outdoor lifestyle. Additionally, the existing screening trees along the project site would be
preserved, and new landscaping would include private
yards and common usable open space. The proposed
project would be subject to design review as required
by Chapter 15.62 of the City’s Municipal Code. As
such, the proposed project is consistent with this
policy.

Policy COS-5.1: Integrate air quality planning with City land use, economic development, and transportation
planning efforts.

Consistent. As discussed in Section 2.3, Air Quality,
the proposed project would not generate pollutant
emissions in excess of applicable significance
thresholds. As such, the proposed project is consistent with this policy.

Policy COS-5.3: Support alternative transportation
modes and technologies and develop bike- and
pedestrian-friendly neighborhoods to reduce emissions
associated with automobile use.

Consistent. The proposed project would provide
electric vehicle (EV-capable) charging infrastructure
consistent with the latest CALGreen requirements,
which would allow future residents to charge electric
vehicles, in turn reducing air quality emissions from
fossil fueled vehicles. In addition, the proposed project would include landscaped paseos and sidewalks. As
such, the proposed project is consistent with this
policy.

Policy COS-6.1: Encourage green building designs for
new construction and renovation projects within the
City.

Consistent. The proposed project would be required
to comply with current CBC Title 24 standards and
CALGreen. Additionally, the proposed project buildings
would be built all-electric and install solar photovoltaic (PV) systems that would generate renewable energy
consistent with the 2025 Building Energy Efficiency
Standards. As such, the proposed project is consistent
with this policy.
364
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
106 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency Policy COS-7.5: Ensure that new development
provides park land and/or improvements at a fair share
ratio, pursuant to the City’s Parkland Ordinance.

Consistent. Refer to response to Land Use Element
Policy 12-2. In addition, the proposed project is
seeking an open space concession pursuant to the
State’s Density Bonus Law for the construction of
17,214 square feet of common open space,
representing approximately 9 percent of the total site
area instead of 25 percent (approximately 47,955
square feet) of the total site area typically required
under the Municipal Code. As such, with the approval
of the open space concession and payment of all
public benefits fees in accordance with the Municipal
Code Chapter 14.16, the proposed project is
consistent with this policy.

Policy COS-8.1: Balance the benefits of development
with a project’s potential impacts to cultural resources.

Consistent. As discussed in Section 2.5, Cultural
Resources, the project site does not contain known
cultural resources; however, there is the potential for unknown or undiscovered resources to be uncovered
through ground-disturbing construction activities. The
proposed project would be required to implement
mitigation measures, which would reduce potential
impacts to cultural resources to a level that is less than significant. MM CUL-1 would require a Worker
Environmental Awareness Program (WEAP) training, a
site survey conducted by a qualified Archaeologist,
and archaeological monitoring. MM CUL-2 would
require consultation with a qualified Archaeologist in
the event that buried archaeological resources are
discovered during construction, as well as inadvertent
discovery procedures. MM CUL-3 would require
consultation with the County Coroner to determine
whether human remains discovered during
construction are Native American in origin. If the
County Coroner determines that human remains
discovered during construction are Native American in
origin, further coordination with the NAHC for
identifying an MLD and for treating and reburying any
discovered human remains and associated grave
goods would be required. Implementation MM CUL-1,
MM CUL-2, and MM CUL-3 would ensure that
potential impacts to archaeological resources will be
reduced to a level of less than significant. As such, the proposed project is consistent with this policy.
365
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 107
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency Safety Element
Policy S-1.1: Avoid development in areas susceptible
to erosion and sediment loss.

Consistent. As discussed in Section 2.7, Geology and
Soils, grading and earthwork activities associated with project construction would expose soils to potential
short-term erosion by wind and water. However,
project construction activities would be required to
comply with applicable City requirements to control
erosion and reduce or eliminate stormwater runoff
containing sediment, including Aliso Viejo Municipal
Code Chapter 13.08, Article XIII, Erosion Control,
which requires the implementation of erosion and
sediment control measures. Project construction
activities would also be required to comply with
applicable water quality measures, including the City’s Water Quality Ordinance (Municipal Code Chapter

7.35, Stormwater Management), which include
conditions and requirements established by the City
related to the reduction or elimination of stormwater
runoff pollutants during construction and operational
phases of the proposed project. As such, the proposed
project is consistent with this policy.

Policy S-1.2: Investigate specific geologic conditions
underlying all new development or redevelopment
proposals in areas where potential fault rupture,
liquefaction, slope instability or other geological
hazards are suspected.

Consistent. As discussed in Section 2.7, Geology and
Soils, the geologic conditions associated with
development of the project site have been investigated
in the Geotechnical Investigation. The project site is
not susceptible to potential fault rupture or liquefaction.

Although the northern and western boundaries of the
project site are mapped as having landslide potential
by the General Plan, implementation of COA GEO-1b
would require landslide susceptibility monitoring by a
licensed California Geotechnical Engineer or Certified
Engineering Geologist. In addition to site-specific
geotechnical recommendations associated with slope
instability, the proposed project would also implement
those associated with potential earthquake ground
shaking, slope instability, or other geological hazards identified in the Geotechnical Investigation, as required by the Municipal Code and through implementation of
COA GEO-1a. As such, the proposed project is
consistent with this policy.

Policy S-2.3: Ensure adequate fire equipment access
and fire suppression resources to all developed and
open space areas within the City.

Consistent. The proposed project would install one
fire hydrant consistent with fire flow requirements for the proposed project in accordance with California Fire 366
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
108 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Aliso Viejo General Plan Policies and Actions Project Consistency Code guidelines and Municipal Code Chapter 13.04
Fire Regulations.

The proposed project would be required to comply with
all City and Orange County Fire Authority (OCFA)
requirements for fire prevention and safety measures,
including site access and would be subject to approval
by the City and OCFA. As such, the proposed project
is consistent with this policy.

Policy S-3.1: Require that new development and
redevelopment minimize stormwater and urban runoff
into drainage facilities by incorporating on-site design features such as detention basins, water features, or
other suitable strategies. Where feasible, support the
use of common detention facilities serving more than
one development.

Consistent. Refer to response to Land Use Element
Policy LU-4.4 and Conservation/Open Space Element
Policy COS-1.4.

Policy S-5.3: Apply design techniques and standards
that employ adequate street and property lighting and
place an increased emphasis on public areas to
reduce potential criminal activity in new development
and reuse projects.

Consistent. All lighting installed as part of the
proposed project would be subject to compliance with
the City’s lighting requirements. In addition, the
proposed project would be required to comply with the
City’s Crime Prevention Through Environmental
Design (CPTED) requirements in accordance with
Municipal Code Section 15.50.020, CPTED Safety
Requirements. Prior to issuance of a building permit,
Orange County Sheriff’s Department (OCSD) would
review the proposed project plans to ensure the
proposed project adheres to all applicable security
requirements. As such, the proposed project is
consistent with this policy.

Noise Element
Policy N-3.1: Ensure stationary noise impacts on
sensitive receptors and noise emanating from
construction activities, private
developments/residences, landscaping activities and
special events are minimized.

Consistent. As discussed in Section 2.13, Noise, the
proposed project would result in less than significant
impacts related to noise. As such, the proposed project is consistent with this policy.

Impacts are therefore considered less than significant, and no mitigation is required.

Mitigation Measures
None required.
367
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 109
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.12 Mineral Resources
Would the project:
a) Result in the loss of availability of a
known mineral resource that would be
of value to the region and the residents
of the State?
b) Result in the loss of availability of a
locally important mineral resource
recovery site delineated on a local
general plan, specific plan or other land
use plan?
Environmental Evaluation
Setting
The information and analysis for Mineral Resources impacts are based on the General Plan. The project site is zoned Business Park-2 and is located in an urbanized area in the City, and no known mineral resources are present on-site.

Would the project:
a) Result in the loss of availability of a known mineral resource that would be of value to the region and the residents of the State?
No impact. The General Plan does not identify any mineral resources in the City. The project site does not support mineral extraction and does not contain any mineral resource zones or other areas designated as containing known mineral resources. The project site is currently developed, zoned Business Park-2, and designated Business Park. The proposed project would redesignate the site to MDR and would rezone the project site to RM. These land use and zoning classifications do not support mineral resource extraction,92 which precludes the potential for impacts associated with mineral resources. No impact would occur.
92 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element, Land Use Policy Map, Figure LU-1.

Website: http://avcity.org/DocumentCenter/View/397/Land-Use-Policy-Map-PDF. Accessed April 10, 2026. □ □ □
□ □ □
368
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
110 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx b) Result in the loss of availability of a locally important mineral resource recovery site delineated on a local general plan, specific plan or other land use plan? No impact. The Aliso Viejo General Plan does not designate any lands within the City as mineral resource deposit areas. There are no existing mineral resource recovery operations on the project site or surrounding area.93 Additionally, the project site is not zoned for mineral resources. Therefore, the proposed project would not result in the loss of availability of known mineral resources of value to the region or result in the loss of a locally important mineral resource recovery site delineated on a local general plan, specific plan, or other land use plan. No impact to mineral resources would occur.

Mitigation Measures
None required.
93 City of Aliso Viejo. 2004. City of Aliso Viejo General Plan, Land Use Element, Land Use Policy Map, Figure LU-1.

Website: http://avcity.org/DocumentCenter/View/397/Land-Use-Policy-Map-PDF. Accessed April 10, 2026. 369
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 111
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.13 Noise
Would the project result in:
a) Generation of a substantial temporary
or permanent increase in ambient noise
levels in the vicinity of the project in
excess of standards established in the
local general plan or noise ordinance, or
applicable standards of other agencies?
b) Generation of excessive groundborne
vibration or groundborne noise levels?
c) For a project located within the vicinity
of a private airstrip or an airport land
use plan or, where such a plan has not
been adopted, within two miles of a
public airport or public use airport,
would the project expose people
residing or working in the project area to
excessive noise levels?
Environmental Evaluation
Setting
The primary noise sources near the project site include traffic from Glenwood Drive to the north and Argonaut to the southeast. The closest noise-sensitive receptors to the project site are single-family residences located north of the project site, across Glenwood Drive.

Existing Conditions
Ambient Noise
Dominant noise sources in the project vicinity include traffic on local roadways, primarily from traffic on Glenwood Drive, which runs along the northern boundary of the project site, Aliso Creek Road, which runs along the western boundary of the project site, and on Argonaut, located near the southeast corner of the project site.

An ambient noise monitoring effort was conducted to document daytime ambient noise levels on the project site. Short-term noise monitoring was conducted by FCS on Monday, April 21, 2026, between □
□
□
□
□
□
□
□
□
370
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
112 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx 10:51 a.m. and 1:06 p.m. The noise measurements were taken during the midday hours, as the midday hours typically have the highest daytime noise levels in urban environments. It should be noted that peak noise hours often vary slightly from peak traffic hours as peak noise hours more closely align with high volume traffic that is still free-flowing, while peak traffic hours often result in slower vehicle speeds due to the volume of traffic on the roadway. The short-term existing noise measurement results are summarized in Table 9, and the locations are shown in Appendix G.

Table 9: Existing Ambient Noise Levels on the Project Site Site ID # Location (Primary Noise Sources) Leq Lmax
ST-1 Southeast corner of property in the greenbelt directly north of driveway entrance, just west of the metal sign. (Traffic from Glenwood Drive and Aliso Creek Road. HVAC system from lab facility at 7 Argonaut).

50.9 61.4
ST-2 Northeast corner of the project site in the parking lot, east of the existing building. (Traffic from Glenwood Drive and Aliso Creek Road.

HVAC system from lab facility at 7 Argonaut).

51.8 60.0
ST-3 Northwest corner of the project site in the parking lot, west of the existing building. (Traffic from Glenwood Drive and Aliso Creek Road.

HVAC system from lab facility at 7 Argonaut).

47.3 81.7
Characteristics of Noise
Noise is defined as unwanted sound. Sound levels are usually measured and expressed in decibels (dB), with 0 dB corresponding roughly to the threshold of hearing. Most of the sounds that we hear in the environment do not consist of a single frequency but rather a broad band of frequencies, with each frequency differing in sound level. The intensities of each frequency add together to generate a sound. Noise is typically generated by transportation, specific land uses, and ongoing human activity.

The standard unit of measurement of the loudness of sound is the dB. The 0 point on the dB scale is based on the lowest sound level that the healthy, unimpaired human ear can detect. Changes of 3 dB or less are only perceptible in laboratory environments. A change of 3 dB is the lowest change that can be perceptible to the human ear in outdoor environments. While a change of 5 A-weighted decibels (dBA) is considered to be the minimum readily perceptible change to the human ear in outdoor environments.

Since the human ear is not equally sensitive to sound at all frequencies, the dBA scale was derived to relate noise to the sensitivity of humans; it gives greater weight to the frequencies of sound to which the human ear is most sensitive. The A-weighted sound level is the basis for a number of various sound level metrics, including the day/night sound level (Ldn) and the Community Noise Equivalent Level (CNEL), both of which represent how humans are more sensitive to sound at night. In addition, the equivalent continuous sound level (Leq) is the average sound energy of time-varying noise over a 371
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 113
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx sample period and the Lmax is the maximum instantaneous noise level occurring over a sample period.

Regulatory Framework
The project site is located within the City of Aliso Viejo, in Orange County. The City addresses noise in the Noise Element of the General Plan and the Municipal Code.

City of Aliso Viejo General Plan
The Noise Element identifies goals and policies to guide development within the City. The following policies are applicable to the proposed project.

Policy N-1.1 Ensure that construction and occupancy of new development are compatible with, and do not exceed thresholds defining the acceptable noise environment in surrounding areas.

Policy N-1.2 Require inclusion of noise-reducing design features in development projects to address the impact of noise on residential development.

Policy N-3.1 Ensure stationary noise impacts on sensitive receptors and noise emanating from construction activities, private developments/residences, landscaping activities and special events are minimized.

Table 10 (Table N-1 in the City’s General Plan Noise Element) summarizes the City’s adopted residential noise standards. The standards represent the maximum acceptable noise levels as measured from any residential property in the City. Accordingly, it is unlawful to cause the noise level on any residential property to exceed the exterior noise standards: (1) for a cumulative period of more than 30 minutes in any hour; (2) by plus 5 dBA for a cumulative period of more than 15 minutes in any hour; (3) by plus 10 dBA for a cumulative period of more than 5 minutes in any hour; (4) by plus 15 dBA for a cumulative period of more than 1 minute in any hour; or (5) plus 20 dBA for any period of time. In addition, any noise that exceeds the interior noise standards established for residential uses:
(1) for a cumulative period of more than 5 minutes in any hour; (2) by plus 5 dBA for a cumulative period of more than 1 minute in any hour; or (3) by plus 10 dBA for any period of time, is unlawful.

Table 10: Residential Noise Standards
Daytime Noise Standards
(7:00 a.m. through 10:00 p.m.)
Nighttime Noise Standards
(10:00 p.m. through 7:00 a.m.)
Interior Noise Standards 55 dBA 45 dBA
Exterior Noise Standards 55 dBA 50 dBA
Note:
dBA = A-weighted decibels
Standards are based on measurements taken from any residential property in the City.

Source: Aliso Viejo General Plan, Noise Element, Table N-1. 372
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
114 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx City of Aliso Viejo Municipal Code
The City of Aliso Viejo has established noise performance standards and permissible hours for construction activities in the Municipal Code. The standards that are applicable to the proposed project are identified below:

Section 8.12.050 Exterior Noise Standards
A. The following exterior noise standards (Table 11), unless otherwise specifically indicated, shall apply to all residential property within the City:

Table 11: Exterior Noise Standards
Land Use Noise Level Time Period
Residential Exterior Noise Standards
Density of less than 10 du/acre 50 dBA 7:00 a.m. – 10:00 p.m. 45 dBA 10:00 p.m. – 7:00 a.m.

Density of more than 10 du/acre 55 dBA 7:00 a.m. – 10:00 p.m. 50 dBA 10:00 p.m. – 7:00 a.m.

Nonresidential Exterior Noise Standards
Commercial 65 dBA 7:00 a.m. – 10:00 p.m.
60 dBA 10:00 p.m. – 7:00 a.m.

Manufacturing/Industrial 70 dBA 24 hours per day
Notes:
dBA = A-weighted decibels
du/acre = dwelling units per acre
Source: Aliso Viejo Municipal Code Section 8.12.050, Exterior Noise Standards.

Section 8.12.060, Interior Noise Standards
Section 8.12.060 establishes interior noise standards for residential property within the City. For all residential properties, the interior noise standard is 55 dBA between the hours of 7:00 a.m. to 10:00 p.m. and 45 dBA between the hours of 10:00 p.m. and 7:00 a.m.

Section 8.12.070, Exemptions
Section 8.12.070 establishes a list of activities that the Municipal Code considers exempt from the provisions of the City’s noise ordinance. Exempt activities that are relevant to the proposed project include:

E. Noise sources associated with construction, repair, remodeling, or grading of any real property, provided the activities do not take place between the hours of 8:00 p.m. and 7:00 a.m. on weekdays, 8:00 p.m. and 8:00 a.m. on Saturday, or at any time on Sunday or a federal holiday.
373
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 115
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Would the project result in:
a) Generation of a substantial temporary or permanent increase in ambient noise levels in the vicinity of the project in excess of standards established in the local general plan or noise ordinance, or applicable standards of other agencies? Short-term Construction Impacts
Less than significant impact. For purposes of this analysis, a significant impact would occur if construction activities would result in a substantial temporary increase in ambient noise levels in excess of the City’s established standards applicable to construction noise.

Municipal Code Section 8.12.070 establishes allowable hours and noise standards for construction activities and equipment. Construction activities, including the operation of any tools or equipment used in construction, are allowed between the hours of 7:00 a.m. through 8:00 p.m. Monday through Friday and from 8:00 a.m. through 8:00 p.m. Saturday. Construction activities on Sundays and federal holidays are prohibited all hours.

While the City does not establish noise level thresholds for construction activities, this analysis uses the noise limits established by the Federal Transit Administration (FTA) to identify the potential for impacts due to substantial temporary construction noise. The FTA identifies construction noise limits in the Transit Noise and Vibration Impact Assessment Manual.94 During daytime hours, a significant temporary increase would be an increase in excess of the average daily noise level of 80 dBA Leq(8-hr) as measured at a receiving residential land use and 85 dBA Leq(8-hr) as measured at a receiving commercial land use.

Noise impacts from construction activities associated with the proposed project would be a function of the noise generated by construction equipment, equipment location, sensitivity of nearby land uses, and the timing and duration of the construction activities.

The site preparation phase, which includes excavation and grading of the site, tends to generate the highest noise levels because the noisiest construction equipment is earthmoving equipment. Typical operating cycles for these types of construction equipment may involve 1 or 2 minutes of full power operation followed by 3 or 4 minutes at lower power settings. A conservative but reasonable assumption is that this equipment would operate simultaneously and continuously over at least a 1- hour period in the vicinity of the closest existing sensitive receptors but would move linearly over the project site during earthmoving operations, spending a relatively short amount of time adjacent to any one receptor. A characteristic of sound is that each doubling of sound sources with equal strength increases a sound level by 3 dBA. These worst-case construction noise levels would only occur during the site preparation phase of development.

The closest noise-sensitive residential receptor to the proposed project site is the single-family residence located north, across Glenwood Drive. This closest noise-sensitive receptor would be 94 Federal Transit Administration (FTA). 2018. Transit Noise and Vibration Impact Assessment Manual. September. 374
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
116 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx located approximately 250 feet from the nearest construction footprint where multiple pieces of heavy construction equipment would potentially operate at the project site. At this distance, relative worstcase hourly average construction noise levels would range up to 64 dBA Leq for this receptor. The reasonable worst-case calculated 8-hour average noise level would be 60 dBA Leq(8-hr), as measured at this nearest sensitive receptor. The calculation spreadsheet with the detailed modeling assumptions is included in Appendix G. These calculated worst-case construction noise levels do not exceed the FTA’s 80 dBA Leq(8-hr) threshold as measured at the nearest residential receptors.

The closest commercial receptor to the proposed project site is the Ambry Genetics office building located directly east of the project site. This closest commercial receptor would be located approximately 50 feet from the nearest construction footprint where multiple pieces of heavy construction equipment would potentially operate at the project site. At this distance relative worstcase hourly average construction noise levels would range up to 82 dBA Leq at this receptor. The reasonable worst-case calculated 8-hour average noise level would be 75 dBA Leq(8-hr), as measured at this nearest commercial receptor. The calculation spreadsheet with the detailed modeling assumptions is included in Appendix G. These calculated worst-case construction noise levels do not exceed the FTA’s 85 dBA Leq(8-hr) threshold as measured at the nearest commercial receptor.

Therefore, temporary or periodic noise impacts from construction activities associated with implementation of the proposed project would be less than significant.

Furthermore, the proposed project would be required to comply with the City’s permissible hours for construction (7:00 a.m. through 8:00 p.m. Monday through Friday and 8:00 a.m. through 8:00 p.m.

Saturday), which would ensure that construction noise would not result in a substantial increase in nighttime noise levels in the project vicinity. Therefore, the proposed project would not result in a substantial temporary increase in ambient noise levels at off-site sensitive receptors above established standards, and construction noise impacts on sensitive receptors in the project vicinity would be less than significant.

Operational/Stationary Source Noise Impacts
Less than significant impact. A significant impact would occur if the proposed project would result in an exceedance of the City’s noise performance standards for stationary noise sources. A significant impact would occur if operational noise levels generated by stationary noise sources at the proposed project site would result in a substantial permanent increase in ambient noise levels in excess of any of the noise performance thresholds established by the City.

As identified in the Project Description, the proposed project’s density would be 13.2 du/acre.

Therefore, the City’s applicable exterior daytime (7:00 a.m. through 10:00 p.m.) noise performance standard is 55 dBA Leq and the applicable exterior nighttime (10:00 p.m. through 7:00 a.m.) noise performance standard is 50 dBA Leq as measured at the nearest residential receptors.

Implementation of the proposed project would include operation of new mechanical ventilation equipment. Noise level ratings for residential-grade mechanical ventilation equipment systems range from 55 dBA to 70 dBA Leq at a distance of 3 feet.
375
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 117
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx The nearest noise-sensitive residential receptor to the proposed rooftop mechanical ventilation equipment is the single-family residence located north of the project site, across Glenwood Drive.

Rooftop mechanical ventilation equipment could be located approximately 265 feet from this closest sensitive receptor. At this distance, the highest noise rating and assuming no shielding from intervening structures or terrain, noise generated by typical mechanical ventilation equipment would attenuate to below 15 dBA Leq as measured at the nearest residential property line. The noise calculation sheet is provided in Appendix G.

These operational noise levels would not exceed the City’s most stringent nighttime noise performance thresholds of 50 dBA Leq as measured at the nearest residential property line. In addition, they would not exceed existing ambient noise levels on the project site, which, as noted above, range from 47.3 dBA to 51.8 dBA Leq. Therefore, mechanical ventilation system operational noise levels would not result in a substantial permanent increase in noise levels in excess of established standards. The impact of mechanical ventilation equipment operational noise levels on sensitive off-site receptors would be less than significant.

Operational/Mobile Source Noise Impacts
Less than significant impact. A significant impact would occur if project-generated traffic would result in a substantial increase in ambient noise levels compared with those that would exist without the proposed project. Typically, a doubling of the Average Daily Traffic (ADT) hourly volumes on a roadway segment is required in order to result in an increase of 3 dBA in traffic noise levels, which, as discussed in the characteristics of noise discussion above, is the lowest change that can be perceptible to the human ear in outdoor environments. Therefore, for the purposes of this analysis, a doubling of the existing ADT volumes would result in a substantial permanent increase in traffic noise levels.

According to the Trip Generation Assessment prepared by Urban Crossroads (Appendix I),95 existing conditions of the office building currently generates approximately 500 daily trips. The proposed project would generate up to 356 average daily trips. This results in a net reduction of 144 daily trips. Similarly, during the PM peak-hour, the existing office building generates 77 trips, while the proposed project would generate 31 PM peak-hour trips, representing a reduction of 46 peak-hour trips.

Since the proposed project would result in a decrease in both ADT and peak-hour traffic volumes compared to existing conditions, roadway noise levels along adjacent roadway segments would correspondingly decrease or remain essentially unchanged. Therefore, the proposed project would not result in a substantial permanent increase in traffic noise levels. This impact would be less than significant.
b) Generation of excessive groundborne vibration or groundborne noise levels? Less than significant impact. A significant impact would occur if the proposed project would generate groundborne vibration or groundborne noise levels in excess of established standards. The 95 Urban Crossroads. 2026. Presidio Residential Trip Generation and VMT Assessment. July 20. 376
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
118 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx City has not established requirements regarding construction vibration impacts; therefore, for the purposes of this analysis, the FTA guidelines for vibration impacts are used to determine potential significant construction- and operation-related vibration impacts.96 This section analyzes both construction and operational groundborne vibration and noise impacts.

Groundborne vibrations consist of rapidly fluctuating motions within the ground that have an average motion of zero. Vibrating objects in contact with the ground radiate vibration waves through various soil and rock strata to the foundations of nearby buildings. Groundborne noise is generated when vibrating building components radiate sound, or noise, generated by groundborne vibration. In general, if groundborne vibration levels do not exceed levels considered to be perceptible, then groundborne noise levels would not be perceptible in most interior environments. Therefore, this analysis focuses on determining exceedances of groundborne vibration levels.

Short-term Construction Vibration Impacts
Of the variety of equipment that would be used during construction, small vibratory rollers would produce the greatest groundborne vibration levels. Impact equipment such as pile drivers would not be used during construction of the proposed project. Small vibratory rollers produce groundborne vibration levels ranging up to 0.101 inch per second (in/sec) peak particle velocity (PPV) at 25 feet from the operating equipment.97
The closest structure to the project site is an Ambry Genetics office building directly east of the project site, located approximately 50 feet from the nearest construction footprint where small vibratory rollers would potentially operate. At this distance, groundborne vibration levels would range up to 0.03 in/sec PPV from operation of a small vibratory roller at the nearest project boundary. This is well below the FTA’s Construction Vibration Impact Criteria of 0.5 PPV for this type of building, a commercial structure of engineered concrete and steel. As a result, construction of the proposed project would not expose the nearby office buildings to groundborne vibration levels in excess of their applicable FTA damage criteria, and this impact would be less than significant.

Operational Vibration Impacts
Implementation of the proposed project would not include any new permanent sources of groundborne vibration that would expose persons in the project vicinity to groundborne vibration levels that could be perceptible without instruments at any existing sensitive land use in the project vicinity. Additionally, there are no active sources of groundborne vibration in the project vicinity that would produce vibration levels that would be perceptible without instruments within the project site.

Therefore, there would be no impact related to operational groundborne vibration. 96 Federal Transit Administration (FTA). 2018. Transit Noise and Vibration Impact Assessment Manual. September. 97 Compilation of scientific and academic literature, generated by the Federal Transit Administration (FTA) and Federal Highway Administration (FHWA).
377
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 119
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx c) For a project located within the vicinity of a private airstrip or an airport land use plan or, where such a plan has not been adopted, within two miles of a public airport or public use airport, would the project expose people residing or working in the project area to excessive noise levels?
No impact. The nearest airport to the project site is John Wayne Airport, located approximately 9.7 miles northwest of the project site. While aircraft noise is occasionally audible at the project site, because of the distance from the airport and the orientation of runways and flight patterns, the project site does not lie within the 60 dBA CNEL noise contour of John Wayne Airport and is not located within an airport land use plan. Therefore, implementation of the proposed project would not expose persons residing or working in the project vicinity to noise levels from airport activity that would exceed normally acceptable standards for the proposed land use development, and no impact would occur.

Mitigation Measures
None required.
378
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
120 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.14 Population and Housing
Would the project:
a) Induce substantial unplanned
population growth in an area, either
directly (for example, by proposing new
homes and businesses) or indirectly (for
example, through extension of roads or
other infrastructure)?
b) Displace substantial numbers of existing
people or housing, necessitating the
construction of replacement housing
elsewhere?
Environmental Evaluation
Setting
According to the California Department of Finance (DOF), the City had a population of 49,945 persons as of January 1, 2026.
98 Would the project:
a) Induce substantial unplanned population growth in an area, either directly (for example, by proposing new homes and businesses) or indirectly (for example, through extension of roads or other infrastructure)?
Less than significant impact. As described above, the City had a provisional population estimate of 49,945 persons as of January 1, 2026.
99 The 2004 Aliso Viejo General Plan Final Environmental Impact Report (General Plan Final EIR) anticipated a population of 48,071 persons at buildout. The buildout population identified in the General Plan Final EIR has already been exceeded. 98 California Department of Finance (DOF). 2026. E-5 City/County Population and Housing Estimates for Cities, Counties, and the State, 2020-2025. Website: https://dof.ca.gov/forecasting/demographics/estimates/e-5-population-and-housingestimates-for-cities-counties-and-the-state-2020-2026/. Accessed May 12, 2026. 99 Ibid.
□ □ □
□ □ □
379
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 121
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx According to the DOF, the City has an average of 2.53 persons per household in 2026.100 The proposed project would include the construction of 58 3-story townhomes, which would increase the City’s population by up to 147 persons based on the DOF’s average household size.101 This is approximately 0.3 percent of the City’s existing population, which is a negligible increase in the City’s total population.

SCAG is the designated Metropolitan Planning Organization (MPO) for six counties (Los Angeles, Orange, San Bernardino, Riverside, Ventura, and Imperial) and 191 cities, including the City of Aliso Viejo. As the federally-designated MPO, SCAG is responsible for developing and adopting regional housing, population, and employment growth forecasts for local Orange County governments, among other counties. The latest SCAG Regional Transportation Plan/Sustainable Communities Strategy (RTP/SCS) was adopted in April 2024.102
While the 2024 RTP/SCS does not provide population projections below the county-level, the 2024 RTP/SCS states that a rough estimate of the future jurisdiction-level population based on Connect SoCal’s household forecast can be derived using county-level population to housing ratio.103 Using the 2050 Orange County population to housing ratio of 2.745, and the City’s projected number of households, Aliso Viejo is projected to have a population of approximately 56,000 for the year 2050.104 As such, the proposed project would not exceed SCAG’s growth projections for the City.

Furthermore, in 2021, SCAG adopted the 6th Cycle Final Regional Housing Needs Assessment (RHNA) Allocation Plan, which assigns a share of the region’s future housing need to each jurisdiction in the SCAG region. The City’s share of the region’s new housing need for the 2021–2029 planning period as established by SCAG in the RHNA is 1,195 units. Of these, the City’s housing need includes 390 units for very-low-income households, 214 for low-income households, 205 for moderate-income households, and 386 for above-moderate-income households.105 The proposed project would provide 58 residential units including three very-low-income units and 55 market-rate units. Therefore, the proposed project would help to accommodate the RHNA housing allocation for the City in order to meet housing needs.
100 California Department of Finance (DOF). 2026. E-5 City/County Population and Housing Estimates for Cities, Counties, and the State, 2020-2025. Website: https://dof.ca.gov/forecasting/demographics/estimates/e-5-population-and-housingestimates-for-cities-counties-and-the-state-2020-2026/. Accessed May 12, 2026. 101 2.53 persons per household * 58 residential units = 146.74 persons, or approximately 147 persons. 102 Southern California Association of Governments (SCAG). 2024. The Southern California Association of Governments’ 2024–2050 Regional Transportation Plan/ Sustainable Communities Strategy. Website: https://scag.ca.gov/connectsocal. Accessed April 10, 2026. 103 Southern California Association of Governments (SCAG). 2024. 2024–2050 Connect SoCal 2024 Demographics & Growth Forecast. Website: https://scag.ca.gov/sites/default/files/2024-05/23-2987-tr-demographics-growth-forecast-final040424.pdf. Accessed April 10, 2026. 104 20,400 persons x (2.745 persons/household) = 56,000 persons 105 City of Aliso Viejo. 2024. City of Aliso Viejo Adopted 2021–2029 Housing Element. Website:
https://avcity.org/DocumentCenter/View/393/Housing-Element-PDF. Accessed April 10, 2026. 380
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
122 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Additionally, the proposed project would not indirectly induce substantial unplanned population growth through the extension of roads or other infrastructure, as the project site and surrounding area are currently served by adjacent roadways and utilities infrastructure. Therefore, the proposed project would not induce unplanned population growth either directly or indirectly, and impacts would be less than significant.
b) Displace substantial numbers of existing people or housing, necessitating the construction of replacement housing elsewhere?
No impact. There are no existing residences on-site, which precludes the possibility that the proposed project would displace people or housing. As such, no impact would occur.

Mitigation Measures
None required.
381
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 123
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.15 Public Services
Would the project result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the public services:
a) Fire protection?
b) Police protection?
c) Schools?
d) Parks?
e) Other public facilities?
Environmental Evaluation
Setting
The information in this section is based, in part, on correspondence with City of Aliso Viejo public service providers, included as Appendix H of this report. Correspondence consisted of responses to an inquiry sent via email to public service providers on April 7, 2026. Responses were provided to FCS between April 14, 2026, and April 29, 2026.

Fire
The City falls under the jurisdiction of OCFA, which provides services to 23 of Orange County’s 34 cities and all unincorporated areas of the county. OCFA’s services include emergency responses to 911 calls, fire inspections, plan review, public information and education, and arson investigation.

OCFA’s 90th percentile for response times is 8:16.106
The proposed project would be served by OCFA Fire Station 57, OCFA Fire Station 22, and OCFA Fire Station 39. OCFA Fire Station 57, the closest OCFA Fire Station to the project site, is located approximately 1.62 miles away at 57 Journey. OCFA Fire Station 22 is located approximately 1.63 miles away at 24001 Paseo de Valencia in Laguna Woods and OCFA Fire Station 39 is located approximately 2.38 miles away at 24241 Avila Road in Laguna Niguel. Fire service response from the 106 Whittaker, Paul. Division Chief, Strategic Services, Orange County Fire Authority (OCFA). Personal communication:
email. Forwarded by Todd Letterman, OCFA. April 23, 2026. □
□
□
□
□
□
□
□
□
□
□
□
□
□
□
382
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
124 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx three closest stations would consist of a total of four engines, one truck, and one Battalion Chief, with a total of 21 all-risk personnel.107 OCFA Fire Station 57 also serves as a Division Headquarters, housing the local Fire Chief, administrative staff, and community educator.

Police
The City contracts with OCSD for its law enforcement needs. OCSD is Orange County’s mutual aid agency and contracts with 13 contract cities in its service area and currently uses a workload-based staffing model and has a goal of under 5 minutes for emergency response times.108 Last month, OCSD’s average for emergency response times was 5 minutes and 23 seconds. 109 The Aliso Viejo Station is located at 12 Journey, which is 1.77 miles south of the project site. The staff dedicated to the City includes one Crime Prevention Specialist, one Emergency Management Coordinator, 17.65 Deputies (Patrol, Traffic Motor, School Resource Officer, Special Enforcement Team and Directed Enforcement Team), two Community Service Officers, 1.5 Investigators, and 2.33 Sergeants. The partial numbers are staff whose duties are split among other cities. There are 15 specialized units that can be contacted to provide service to the City when needed and include units such as Canine, Gang Enforcement, Homicide Detail, and more.110 Schools
The project site falls within the Capistrano Unified School District (CUSD). During the 2025–2026 school year, the district enrolled 46,429 students.111 CUSD serves the City of San Juan Capistrano, City of Dana Point, City of Laguna Niguel, and the City of San Clemente, as well as a portion of the City of Aliso Viejo, City of Mission Viejo, City of Rancho Santa Margarita, and a very small portion of the Cities of Laguna Beach and Laguna Woods and a portion of unincorporated Orange County.112 The proposed project is within the service area of Oak Grove Elementary School, Aliso Viejo Middle School, and Aliso Niguel High School.113 During the 2025–2026 school year, Oak Grove Elementary School enrolled 519 students, Aliso Viejo Middle School enrolled 804 students, and Aliso Niguel High School enrolled 2,534 students.114
107 Whittaker, Paul. Division Chief, Strategic Services, Orange County Fire Authority (OCFA). Personal communication:
email. Forwarded by Todd Letterman, OCFA. April 23, 2026. 108 Buhr, Ryan. Chief of Police, Aliso Viejo Police Services. Personal communication: email. April 29, 2026. 109 Ibid.
110 City of Aliso Viejo. 2025. Police Services. Website: https://avcity.org/212/Police-Services. Accessed April 10, 2026. 111 California Department of Education Data Reporting Office. 2026. 2025–2026 Enrollment by Grade, Capistrano Unified School District (30-66464). Website:
https://dq.cde.ca.gov/dataquest/dqcensus/EnrGrdLevels.aspx?cds=3066464&agglevel=district&year=2025-26. Accessed May 12, 2026.
112 King Consulting. 2026. Developer Fee Justification Study. Capistrano Unified School District. Website:
https://drive.google.com/file/d/1aJ41P9yOjicsQr1d2qM1B-RSeAGU8cqQ/view. Accessed April 10, 2026. 113 Ibid.
114 California Department of Education Data Reporting Office. 2026. 2025–2026 Enrollment by Grade, Capistrano Unified School District (30-66464). Website:
383
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 125
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Level 1 Developer Fees are established by the State and are considered a basic mitigation fee that all residential and commercial projects must pay. In January 2026, the State Allocation Board approved the Level 1 Developer Fee of $5.38 per square foot of residential development.115 Parks
The City of Aliso Viejo Recreation & Community Services Department owns and manages Vista Park and Iglesia Park, which are a total of 7.4 acres. Additionally, Aliso Viejo Community Association (AVCA) is responsible for 21 parks (approximately 179 acres) and 600 acres of landscaping. 116 The
closest park is Ridgecrest Park, located 220 feet (0.04 mile) northwest of the project site, across the Aliso Creek Road/Glenwood Drive intersection. Ridgecrest Park is a private park owned and managed by AVCA.117 It contains barbecue pits, basketball courts, shaded picnic tables and benches, a shaded tot lot, tennis courts with lights, pickleball courts, and bocce ball courts. Crosswalks and traffic lights are available on both Glenwood Drive and Aliso Creek Road, allowing for pedestrian access to Ridgecrest Park. The two next closest parks are Glenwood Community Park and Pinewood Park. Glenwood Community Park is located 0.13 mile northwest of the project site on the opposite side of Glenwood Drive, and Pinewood Park is located 0.22 mile east of the project site on the opposite side of the business park.

Libraries
Orange County provides a range of public libraries, cultural facilities, and recreation services. The nearest Orange County Public Library branch to the project site is the Laguna Woods Branch, located at 24266 El Toro Road in the City of Laguna Woods, approximately 1.18 miles northwest of the project site. Additionally, the Aliso Viejo Branch is located at 1 Journey, approximately 1.64 miles south of the project site. Orange County Public Libraries provides library services to the City of Aliso Viejo through its system-wide network of 32 branches across the county. Aliso Viejo residents have access to all services as membership is not specific to individual branches; as such, residents of the City have access to resources and services throughout the entire Orange County Public Library system. The most current tenant projections are from 2023, during which the Aliso Viejo Branch had 140,931 visitors, with an average daily attendance of 470 people.118 The Aliso Viejo Branch reopened in March 2026, after extensive renovations to enhance accessibility and facilities.119 https://dq.cde.ca.gov/dataquest/dqcensus/EnrGrdLevels.aspx?cds=3066464&agglevel=district&year=2025-26. Accessed May 12, 2026.
115 King Consulting. 2026. Developer Fee Justification Study. Capistrano Unified School District. Website:
https://drive.google.com/file/d/1aJ41P9yOjicsQr1d2qM1B-RSeAGU8cqQ/view. Accessed April 10, 2026. 116 Kim, So. Director of Community Development, City of Aliso Viejo. Personal communication: email. April 22, 2026. 117 Aliso Viejo Community Association (AVCA). 2026. Parks. Website: https://avca.net/community/parks. Accessed April 10, 2026.
118 Oakley, Julie. Library Administration, Orange County Public Libraries. Personal communication: email. April 7, 2026. 119 Mcrea, Heather. 2026. Orange County Register. Patrons eagerly check out renovated Aliso Viejo Library. Website:
https://www.ocregister.com/2026/03/25/patrons-eagerly-check-out-renovated-aliso-viejo-library/. Accessed April 10, 2026. 384
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
126 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Would the project result in substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities, need for new or physically altered governmental facilities, the construction of which could cause significant environmental impacts, in order to maintain acceptable service ratios, response times or other performance objectives for any of the public services:
a) Fire protection?
Less than significant impact. According to Division Chief of Strategic Services Paul Whittaker, OCFA has the ability to provide fire protection services to the project site and the proposed project will require an OCFA Secured Fire Protection Agreement, which requires a development impact fee of $600 per unit.
120 The proposed project would install one fire hydrant for firefighting purposes consistent with fire flow requirements for the proposed project in accordance with California Fire Code guidelines stipulated in Municipal Code Chapter 13.04, Fire Regulations, and would connect to existing water lines.

As discussed in Section 2.14, Population and Housing, the proposed project would generate 147 new residents. Fire protection and emergency service by OCFA is currently provided to the area under existing conditions.

As discussed in Section 2.14, Population and Housing, residential uses have been anticipated at the project site by the General Plan and population growth from the proposed project would not exceed SCAG’s growth projections for the City by year 2050 based on the 2024 RTP/SCS. Thus, the 147 new residents would be considered planned growth that would be addressed with existing facilities.

Therefore, the proposed project would not create a need for new or physically altered fire facilities to maintain acceptable service ratios, response times, or other performance objectives.

Furthermore, the proposed project would be required to comply with the California Fire Code, as amended, in accordance with Municipal Code Chapter 13.04, 2025 Edition of the California Fire Code, and would be subject to approval by OCFA. Adherence with fire code standards and approval by OCFA would reduce the potential demand for fire services by decreasing the likelihood and/or severity of a fire emergency at the project site. Implementation of City requirements, including compliance with the California Fire Code and approval of site plans by OCFA, would ensure that there would be no substantial adverse physical impacts associated with the provision of new or physically altered governmental facilities for fire protection services. As such, impacts would be less than significant.
b) Police protection?
Less than significant impact. According to Captain Ryan Buhr, the City’s Chief of Police Services, OCSD utilizes a workload-based staffing model as opposed to a population-to-staff ratio. 121 Currently,
120 Whittaker, Paul. Division Chief, Strategic Services, Orange County Fire Authority. Personal communication: email.

Forwarded by Todd Letterman, Orange County Fire Authority. April 23, 2026. 121 Buhr, Ryan. Chief of Police, Aliso Viejo Police Services. Personal communication: email. April 29, 2026. 385
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 127
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx based on the Department’s patrol allocation model, the OCSD – Aliso Viejo Station is currently short one Deputy.
122
As described above, the proposed project would include the construction of a residential development that consists of 58 townhomes on the approximately 4.4-acre project site ranging from 1,320 to 1,827 square feet in size. Police protection services to the project site occurs under the existing conditions.

While the proposed project would generate an estimated 147 residents, this would be considered planned growth under SCAG’s predictions and would contribute to the City’s RHNA, as discussed in Section 2.14, Population and Housing Question a). Furthermore, according to Captain Buhr, since OCSD relies on a workload-based staffing model reliant on actual demand for police services as opposed to a population-based ratio, the station would staff accordingly irrespective of population growth resulting from the proposed project.123
Because the proposed project would not induce substantial unplanned population growth, it is anticipated that the proposed project would be adequately served by OCSD and would not create a need for new or physically altered police facilities to maintain acceptable service ratios, response times, or other performance objectives. The proposed project would also be required to comply with the City’s Crime Prevention Through Environmental Design (CPTED) requirements in accordance with Municipal Code Section 15.50.020, CPTED Safety Requirements. OCSD would review the project plans to ensure the proposed project adheres to all applicable security requirements prior to issuing the building permit. Implementation of City requirements and approval of site plans by OCSD would further reduce potential impacts concerning police protection services. As such, impacts would be less than significant.
c) Schools?
Less than significant impact. The schools that would serve the proposed project would be Oak Grove Elementary (Transitional Kindergarten [TK] through Grade 5), Aliso Viejo Middle School (Grades 6 through 8), and Aliso Niguel High School (Grades 9 through 12). According to the number of new students for these schools generated as a result of the proposed project, it was estimated that Oak Grove Elementary would expect an additional 13 students, Aliso Viejo Middle School would expect an additional five students, and Aliso Niguel High School would expect an additional five students, for a total of 23 new students.124 CUSD did not identify any potential issues regarding growth associated with the housing development and states that the school district can accommodate the number of projected students.125
122 Buhr, Ryan. Chief of Police, Aliso Viejo Police Services. Personal communication: email. April 29, 2026. 123 Ibid.
124 Hampton, Clark D. Deputy Superintendent, Business and Support Services, Capistrano Unified School District (CUSD).

Personal communication: email. April 14, 2026.
125 Hampton, Clark D. Deputy Superintendent, Business and Support Services, Capistrano Unified School District (CUSD).

Personal communication: email. April 14, 2026.
386
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
128 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx The 2026 Developer Fee Justification Study conducted by CUSD concluded that, while there is capacity for students in TK through Grade 5, student capacity at the CUSD is currently exceeded for Grades 6 through 12.126 The proposed project would be subject to payment of school impact fees in accordance with SB 50. Pursuant to Government Code Section 65995(3)(h), payment of statutory fees is deemed to be “full and complete mitigation of impacts of any legislative or adjudicative act, or both, involving but not limited to the planning, use or development of real property. . .” The developer would be required to pay Level 1 Developer Fees in accordance with Government Code Section 65995(3)(h). Developer fees collected by CUSD pursuant to SB 50 are used for the provision of additional and reconstructed or modernized school facilities. The project applicant would be required to pay all statutory fees in place at the time and demonstrate proof of payment to the City for approval of a building permit. Payment of the Level 1 Developer Fees is considered full mitigation for increased school enrollment as a result of the proposed project. As such, CUSD would be able to accommodate the additional students generated by the proposed project, and potential impacts to schools would be less than significant.
d) Parks?
Less than significant impact. The proposed project would develop up to 58 dwelling units, which would generate an estimated 147 new residents (See Section 2.14, Population and Housing). The new residents would increase the demand on existing neighborhood and regional parks. The additional use would further contribute to the need for maintenance and improvements.

The City’s Municipal Code requires usable open space to equal 25 percent (approximately 47,955 square feet) of the total site area. The proposed project is seeking an open space concession pursuant to the State’s Density Bonus Law for the construction of 17,214 square feet of common open space, representing approximately 9 percent of the total site area. On-site recreational amenities for residents would include a dog play area, a community garden, a recreation/yoga lawn, and a barbecue area with an accompanying shade structure that would offset impacts to park facilities. In addition, the proposed project would install 7,611 square feet of private yards.

The proposed project also includes approximately 84,050 square feet of existing open space located on the site's northern and western portions of the site that would be preserved as part of the proposed project. These preserved areas consist of steeply sloped terrain and are intended to remain in a natural, undeveloped condition for visual buffering and site design purposes. Because these areas do not meet the City’s definition of usable open space, they do not count toward the Municipal Code’s minimum open space requirement.

Furthermore, the applicant would comply with Municipal Code Chapter 14.16, Dedication of Land for Park Facilities and Payment of In Lieu Fees, which requires payment of park and recreation impact fees to offset incremental demand on local parks. By providing on-site recreational amenities that exceed the required minimum open space and paying applicable park development fees, the 126 King Consulting. 2026. Developer Fee Justification Study. Capistrano Unified School District. Website:
https://drive.google.com/file/d/1aJ41P9yOjicsQr1d2qM1B-RSeAGU8cqQ/view. Accessed April 10, 2026. 387
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 129
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx proposed project would ensure that the incremental increase in recreational demand would not result in substantial physical deterioration of existing neighborhood and regional parks.

Although project residents would likely use public parks, implementation of the proposed project would not require new or physically altered park facilities, the construction of which could cause significant environmental impacts. Therefore, impacts would be less than significant. e) Other public facilities?
Less than significant impact. A service letter was sent out to the Orange County Public Libraries Administration about expected impacts from the proposed project on April 7, 2026, and they responded on April 16, 2026.127 The library anticipates that the proposed project’s anticipated population generation would utilize library services and that the increase in visitors would not have a significant impact on the library or its services.128 Although the proposed project would increase demand for library services, the anticipated growth generated by the proposed project would be within the population growth projections anticipated and planned for by local and regional planning documents. The proposed project’s impacts to the overall availability per capita of books, media, computers, and library public service space would not result in significant physical or environmental impacts, as the population growth resulting from the proposed project is within current City projections. Therefore, impacts would be less than significant.

Mitigation Measures
None required.
127 Oakley, Julie. Library Administration, Orange County Public Libraries. Personal communication: email. April 16, 2026. 128 Ibid.
388
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
130 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.16 Recreation
a) Would the project increase the use of
existing neighborhood and regional
parks or other recreational facilities
such that substantial physical
deterioration of the facility would occur
or be accelerated?
b) Does the project include recreational
facilities or require the construction or
expansion of recreational facilities,
which might have an adverse physical
effect on the environment?
Environmental Evaluation
Setting
As previously discussed in Section 2.15, Public Services, the closest park is Ridgecrest Park, located 220 feet (0.04 mile) northwest of the project site on the opposite side of the Aliso Creek Road/Glenwood Drive intersection. Ridgecrest Park is a private park owned and managed by AVCA.129 Crosswalks and traffic lights are available on both Glenwood Drive and Aliso Creek Road, allowing for pedestrian access to Ridgecrest Park. The second two closest parks are Argonaut Park and Pinewood Park. Argonaut Park is located approximately 0.2 mile south of the project site and Pinewood Park is located 0.22 mile east of the project site on the opposite side of the business park.

These parks provide public amenities such as picnic tables, barbecues, playgrounds, basketball courts, and softball fields.
a) Would the project increase the use of existing neighborhood and regional parks or other recreational facilities such that substantial physical deterioration of the facility would occur or be accelerated?
129 Aliso Viejo Community Association. 2026. Parks. Website: https://avca.net/community/parks. Accessed April 10, 2026. □ □ □
□ □ □
389
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 131
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Less than significant impact. The proposed project would develop 58 3-story townhomes. The City has an estimated population of 50,213 persons as of January 1, 2026.130 As discussed previously in Section 2.14, Population and Housing, given that the proposed project would develop up to 58 dwelling units, the proposed project would generate up to 147 new residents, which would increase the demand on existing neighborhood and regional parks. The additional use would further contribute to the need for maintenance and improvements.

The City’s Municipal Code requires usable open space to equal 25 percent (approximately 47,955 square feet) of the total site area. As previously mentioned under Impact 2.15(d), the proposed project is seeking an open space concession pursuant to the State’s Density Bonus Law for the construction of 17,214 square feet of common open space, representing approximately 9 percent of the total site area. The existing open space located on the site’s northern and western portions of the site that would be preserved does not count toward the Municipal Code’s minimum open space requirement.

On-site recreational amenities would include a dog play area, a community garden, a recreation/yoga lawn, and a barbeque area with an accompanying shade structure and the proposed project would also incorporate 7,611 square feet of private yards, lessening the need for use of existing parks and recreational facilities by project residents. It is expected that these on-site recreational amenities would reduce the demand on neighborhood and regional parks and recreation facilities, and thereby reduce the proposed project’s contribution to the deterioration of existing parks and recreational facilities.

To address the incremental increase in demand associated with the proposed project, the applicant would comply with Municipal Code Chapter 14.16, Dedication of Land for Park Facilities and Payment of In Lieu Fees, which requires developers to dedicate land for park facilities or pay park and recreation impact fees. By providing on-site recreational amenities that exceed the required minimum open space and paying applicable park development fees, the proposed project would ensure that the incremental increase in recreational demand would not result in substantial physical deterioration of existing neighborhood and regional parks. Therefore, impacts would be less than significant. b) Does the project include recreational facilities or require the construction or expansion of recreational facilities, which might have an adverse physical effect on the environment?
Less than significant impact. As discussed previously, the proposed project would provide a total of 17,214 square feet of usable open space and install 7,611 square feet of private yards, resulting in a combined proposed and existing square footage of 108,875 square feet of open space on-site.

Impacts related to the construction of improvements have been addressed throughout this Draft 130 California Department of Finance (DOF). 2026. E-5 City/County Population and Housing Estimates for Cities, Counties, and the State, 2020-2025. Website: https://dof.ca.gov/forecasting/demographics/estimates/e-5-population-and-housingestimates-for-cities-counties-and-the-state-2020-2025/. Accessed April 10, 2026. 390
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
132 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx IS/MND and would be reduced through the implementation of all mitigation measures included in this Draft IS/MND.

Therefore, impacts would be less than significant.

Mitigation Measures
None required.
391
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 133
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.17 Transportation
Would the project:
a) Conflict with a program plan, ordinance
or policy of the circulation system,
including transit, roadway, bicycle and
pedestrian facilities?
b) Would the project conflict or be
inconsistent with CEQA Guidelines
Section 15064.3, subdivision (b)?
c) Substantially increase hazards due to a
geometric design feature (e.g., sharp
curves or dangerous intersections) or
incompatible uses (e.g., farm
equipment)?
d) Result in inadequate emergency
access?
Environmental Evaluation
Setting
This analysis is based in part on the Trip Generation & VMT Assessment prepared by Urban Crossroads, Inc. for the proposed project on July 20, 2026, and included as Appendix I in this report. 131
Would the project:
a) Conflict with a program plan, ordinance or policy addressing the circulation system, including transit, roadway, bicycle and pedestrian facilities? Less than significant impact.

Circulation System
The proposed project would result in a net reduction of daily trips compared to the existing office use on-site. According to the Trip Generation & VMT Assessment prepared for the proposed project, in its 131 Urban Crossroads, Inc. 2026. Presidio Residential Trip Generation & VMT Assessment. July 20. □ □ □
□ □ □
□ □ □
□ □ □
392
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
134 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx existing condition, the project site generates an average of 500 two-way trips per day, with 73 trips during the AM peak-hour and 77 trips during the PM peak-hour. The proposed project is anticipated to generate 418 two-way trips per day with 25 AM peak-hour trips and 32 PM peak-hour trips. Therefore, implementation of the proposed project would result in a net reduction of 82 two-way trips per day with a net reduction of 50 AM peak-hour trips and a net increase of 46 PM peak-hour trips when compared to the existing office use.132 The City’s Transportation Impact Guidelines indicate that projects that generate 1,600 ADT and add 51 or more trips during either the AM or PM peak-hours would result in potential significant impacts.133 However, the proposed project is anticipated to generate fewer than 1,600 net new daily trips and fewer than 50 net new peak-hour trips. Therefore, impacts would be less than significant.

Transit Facilities
Public transportation services are provided by Orange County Transportation Authority (OCTA). Bus Route 90 provides service from Tustin to Dana Point via Moulton Parkway; a bus stop is located near the intersection of Moulton Parkway and Glenwood Drive. The nearest bus stop to the project site is the Moulton-Glenwood bus stop, located along Moulton Parkway, 0.66 mile east of the project site.

There are no existing or planned transit facilities adjacent to the project site. Project implementation would not conflict with a program plan, ordinance, or policy addressing transit facilities.

Roadway Facilities
Vehicular access to the project site is currently provided from a driveway at the southeast corner of the project site along Argonaut. This existing driveway would be retained and utilized to serve the proposed project. An internal private roadway system would provide access to each unit’s parking garage as well as to guest parking spaces that would be distributed throughout the site. Roadway facilities would continue to serve the project site and surrounding development. The proposed project would not involve modifications to any existing roadways within the area and, thus, would not conflict with a program, plan, ordinance, or policy addressing roadway facilities.

Bicycle Facilities
The Aliso Viejo General Plan Circulation Element (Figure C-2) identifies existing bicycle facilities within the City.134 According to the General Plan Circulation Element and the OCTA 2009 Commuter Bikeways Strategic Plan, Class II on-road bicycle lanes currently exist along both sides of Glenwood Drive.135 Additionally, Aliso Creek Road and Moulton Parkway have Class II on-road bicycle lanes.136 There are no planned bicycle facilities near the project site. The proposed project would not involve 132 Urban Crossroads, Inc. 2026. Presidio Residential Trip Generation & VMT Assessment. July 20. 133 City of Aliso Viejo. 2020.Transportation Impact Guidelines for CEQA and General Plan Consistency. Website:
https://avcity.org/DocumentCenter/View/4395/Traffic-Impact-Analysis-Guidelines?bidId=. Accessed May 12, 2026. 134 City of Aliso Viejo. 2004. General Plan Circulation Element, Figure C-2, Bikeways. Website:
https://avcity.org/DocumentCenter/View/392/Circulation-Element-PDF. Accessed April 10, 2026. 135 Alta Planning + Design, KOA Corporation. 2009. Final 2009 OCTA Commuter Bikeways Strategic Plan for the Orange County Transportation Authority. Map 1-1. Website: https://www.octa.net/pdf/bikeways09.pdf. Accessed April 10, 2026. 136 Orange County Transportation Authority (OCTA). 2026. Bikeways Planning, Orange County Bikeways Map. Website:
https://www.octa.net/getting-around/active/oc-bike/bikeways-planning/overview/. Accessed April 10, 2026. 393
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 135
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx modifications to any of these roadways or bicycle lanes and thus would not conflict with a program, plan, ordinance, or policy addressing bicycle facilities.

Pedestrian Facilities
Pedestrian facilities, including crosswalks and sidewalks, are currently available along both sides of Glenwood Drive north of the project site, along both sides of Aliso Creek Road west of the project site, and along both sides of Argonaut south and west of the project site. Signalized crosswalks are available at the intersection of Glenwood Drive and Aliso Creek Road located at the northwest corner of the project site and at the intersection of Glenwood Drive and Argonaut east of the project site.

Non-signalized crosswalks are available at the intersection of Argonaut located east of the project site. Pedestrians would circulate within the site via proposed internal pedestrian walkways and concrete sidewalks. The proposed internal pedestrian walkways and sidewalks would connect to the existing sidewalks along Argonaut via the existing driveway on the southeastern corner of the project site.

The proposed project would not conflict with any program, plan, ordinance, or policy addressing the circulation system, including transit, roadway, bicycle, or pedestrian facilities. Therefore, impacts would be less than significant.
b) Would the project conflict or be inconsistent with CEQA Guidelines Section 15064.3, subdivision (b)?
Less than significant impact. The project-specific Trip Generation and VMT Assessment (Appendix I) was prepared to evaluate transportation impacts pursuant to CEQA Guidelines Section 15064.3(b) and SB 743. The VMT assessment applies the City’s Transportation Impact Guidelines to determine whether the proposed project meets established VMT screening criteria and would be expected to result in a less than significant impact or require additional VMT analysis.

VMT is a measurement of miles traveled by vehicles within a specified region and for a specified period of time. VMT is a measure of the use and efficiency of the transportation network and is calculated based on individual vehicle trips generated and their associated trip lengths. VMT accounts for two-way (round-trip) travel and is often estimated for a typical weekday for the purposes of measuring transportation impacts.

In September 2013, SB 743 was signed into law, which fundamentally changed transportation impact analysis as part of CEQA compliance. These changes include the elimination of auto delay, Level of Service (LOS), and similar measurements of vehicular roadway capacity and traffic congestion as the basis for determining significant traffic impacts. SB 743 identifies VMT as the most appropriate CEQA transportation metric. The justification for this paradigm shift is that LOS impacts lead to improvements that increase roadway capacity and, thus, induce more traffic and GHG emissions. 394
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
136 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx In May 2020, the City adopted its Aliso Viejo Transportation Impact Guidelines for CEQA and General Plan Consistency (AVTIG), which serves as the City’s transportation analysis guidelines.137 The AVTIG includes screening criteria that are intended to provide a simplified way to determine whether a project’s VMT would be expected to cause a less than significant CEQA transportation impact without having to conduct a detailed VMT analysis. Below is a discussion of the various screening criteria outlined in the AVTIG and an analysis of whether the proposed project would be “screened” from requiring a detailed VMT analysis, either in its entirety or partially based on individual land uses.

City Guidelines outline appropriate screening criteria for identifying when a proposed land use project is expected to have a less than significant impact, thus avoiding the need for a more detailed analysis. The screening criteria are divided into the following:
• Step 1: Transit Priority Areas (TPA) Screening
• Step 2: Low VMT Area Screening
• Step 3: Project Type Screening
A land use project needs only to meet one of the above screening criteria to result in a less than significant impact.

Consistent with guidance identified in the City Guidelines, projects located within a TPA or Highquality Transit Area (HQTA) (i.e., within 0.5 mile of an existing “major transit stop” or an existing stop along a “high-quality transit corridor”) may be presumed to have a less than significant impact absent substantial evidence to the contrary. However, consistent with City Guidelines, Aliso Viejo does not have any TPAs within the City.138 Therefore, the Step 1: TPA screening criterion is not met.

The proposed project is not located within a low VMT-generating area and would not qualify for Step 2: Low VMT Area screening criterion.
139
The City Guidelines state that local-serving uses such as day care centers, non-destination hotels, affordable housing, places of worship, municipal services, and other local essential services may be presumed to have a less than significant impact as local-serving in nature and would tend to shorten vehicle trips. The proposed project does not include any local-serving uses. However, according to the Trip Generation & VMT Assessment (Appendix I), the City Guidelines also consider small projects that generate fewer than 110 net new daily vehicle trips to have a less than significant VMT impact.

Based on the results of the VMT assessment, the proposed residential development that would replace an existing office use is projected to result in a net reduction in daily vehicle trips compared to existing conditions. The proposed project is expected to generate a net reduction of 144 daily vehicle trips. Since the proposed project would result in a reduction of daily vehicle trips, it is below the 110 137 City of Aliso Viejo. 2020.Transportation Impact Guidelines for CEQA and General Plan Consistency. Website:
https://avcity.org/DocumentCenter/View/4395/Traffic-Impact-Analysis-Guidelines?bidId=. Accessed April 10, 2026. 138 City of Aliso Viejo. 2020.Transportation Impact Guidelines for CEQA and General Plan Consistency. Page 18. Website:
https://avcity.org/DocumentCenter/View/4395/Traffic-Impact-Analysis-Guidelines?bidId=. Accessed April 16, 2026. 139 Ibid.
395
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 137
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx net new daily vehicle trip threshold.140 Therefore, Step 3: Project Type screening criterion is met.

Based on the City’s VMT screening types and the net reduction of daily vehicle trips, the proposed project meets the Project Type screening criterion and is therefore considered to have a less than significant VMT impact. No additional VMT analysis is required, and impacts would be less than significant.
c) Substantially increase hazards due to a geometric design feature (e.g., sharp curves or dangerous intersections) or incompatible uses (e.g., farm equipment)? Less than significant impact. The proposed project would include the development of a new residential community consisting of 58 residential units. Because the General Plan land use designation of the proposed project would change to MDR, this would be consistent with the updated land use designation and existing development north of the project site. Therefore, the proposed project would not introduce an incompatible use to the project site. Additionally, the proposed project would not provide off-site roadway improvements that could substantially increase hazards due to a design feature. Argonaut currently provides access to the project site. No modifications to Argonaut are proposed. Furthermore, the internal roadway system would provide access to each residential unit. This internal roadway would be consistent with the Municipal Code Chapter 10, Streets and Sidewalks. As previously mentioned under Impact 2.9(f), operation of the proposed project would also be consistent with all applicable OCFA requirements, which would include those for road width and turning radii to facilitate fire department access.

As part of the City’s Site Development Permit process required under Municipal Code Section

15.74.020, Site Development Permits, the proposed project would be reviewed and only approved after finding the proposed development conforms with applicable requirements and standards set forth in the Municipal Code and General Plan, including the Circulation Element’s standards related to design, access, and circulation. The proposed project would be designed to ensure all driveways and ingress/egress points maintain adequate line of sight unobstructed by landscaping, signage, or other barriers.

Additionally, as the proposed project would introduce an urban use within an urbanized area, it would not introduce incompatible elements such as farm equipment. The proposed project is designed to be consistent with the existing residential land uses designated Very Low Density Residential and High Density Residential to the north of the project site. The project would adhere to Municipal Code Section 15.62.050 design review requirements to guarantee safe line of sight and would not create traffic hazards. Therefore, impacts would be less than significant. d) Result in inadequate emergency access?
Less than significant impact. As discussed in Impact 2.9(f), the City has developed an EOP outlining the City’s response to extraordinary emergency situations associated with natural disasters, technological incidents, and national security emergencies. The EOP establishes evacuation routes. 140 Urban Crossroads, Inc. 2026. Presidio Residential Trip Generation and VMT Assessment. July 20. 396
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
138 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Additionally, the General Plan Safety Element identifies evacuation routes in the City. Within the vicinity of the project site, Aliso Creek Road and Glenwood Drive are identified as primary evacuation routes.141
The project site is within Zone 20 of Aliso Viejo’s Evacuation Zones. Designated evacuation zones within Zone 20 include Glenwood Drive, Aliso Creek Road, Aliso Viejo Parkway, and Moulton Parkway.142 The project site is adjacent to both Glenwood Drive and Aliso Creek Road, and construction would not require closure or partial closure of Glenwood Drive or Aliso Creek Road. The proposed project would be constructed completely within the project site and construction equipment would access the project site via Argonaut, which is the main access point to the project site. If any road closures to Argonaut are required, the project applicant and construction crew would be required to coordinate with the City of Aliso Viejo Public Works Department to ensure that emergency access routes are maintained during construction. Thus, construction of the proposed project would not impede the use of surrounding roadways for emergencies or access for emergency response vehicles.

The proposed project would provide internal circulation for emergency vehicle access. The proposed project has been designed to provide emergency service providers access to the site from any of the public streets or the drive aisles. The proposed project has been designed to comply with applicable emergency service provider access standards, including those from OCFA for fire department access, turning radii with an inner radius of 20 feet and an outer radius of 49 feet, and emergency response requirements. The design of the proposed project would provide adequate emergency access consistent with City requirements, including the required number and design of access points and safety features. Therefore, the proposed project would not result in significant impacts to emergency access during construction and/or operation. The proposed project would not impair implementation of or physically interfere with an adopted emergency response plan or emergency evacuation plan.

Impacts would be less than significant.

Mitigation Measures
None required.
141 City of Aliso Viejo. 2004. General Plan. Safety Element. Figure S-1 Safety Policy Map. Website: https:// avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 10, 2026. 142 City of Aliso Viejo. 2024. Citywide Evacuation Zones. Website: https://avcity.org/DocumentCenter/View/3750. Accessed April 10, 2026.
397
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 139
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.18 Tribal Cultural Resources
Would the project:
a) Cause a substantial adverse change in
the significance of a Tribal Cultural
Resource, defined in Public Resources
Code Section 21074 as either a site,
feature, place, or cultural landscape that
is geographically defined in terms of the
size and scope of the landscape, sacred
place, or object with cultural value to a
California Native American Tribe, and
that is:
i) Listed or eligible for listing in the
California Register of Historical
Resources, or in a local register of
historical resources as defined in
Public Resources Code Section
5020.1(k), or
ii) A resource determined by the lead
agency, in its discretion and
supported by substantial evidence,
to be significant pursuant to criteria
set forth in subdivision (c) of Public
Resources Code Section 5024.1. In
applying the criteria set forth in
subdivision (c) of Public Resources
Code Section 5024.1, the lead
agency shall consider the
significance of the resource to a
California Native American Tribe.

Environmental Evaluation
Would the proposed project cause a substantial adverse change in the significance of a TCR, defined in Public Resources Code Section 21074 as either a site, feature, place, or cultural landscape that is □ □ □
□ □ □
□ □ □
398
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
140 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx geographically defined in terms of the size and scope of the landscape, sacred place, or object with cultural value to a California Native American Tribe, and that is:
a) Cause a substantial adverse change in the significance of a Tribal Cultural Resource, defined in Public Resources Code Section 21074 as either a site, feature, place, or a cultural landscape that is geographically defined in terms of the size and scope of the landscape, sacred place, or object with cultural value to a California Native American Tribe, and that is:
i) Listed or eligible for listing in the California Register of Historical Resources, or in a local register of historical resources as defined in Public Resources Code Section 5020.1(k), or
Less than significant impact with mitigation incorporated. A review of the CRHR, local registers of historic resources, a records search conducted at the SCCIC, and a pedestrian survey failed to identify any listed TCRs that may be adversely affected by the proposed project. However, the NAHC SLF results were positive for TCRs on the project site, and subsequent Tribal outreach to obtain additional information pertaining to TCRs within the project site produced negative results. Should any undiscovered TCRs be encountered during project construction, implementation of MM TCR-1 through MM TCR-5 will ensure that potential impacts to TCRs will be reduced to a level of less than significant.
ii) A resource determined by the lead agency, in its discretion and supported by substantial evidence, to be significant pursuant to criteria set forth in subdivision (c) of Public Resources Code Section 5024.1. In applying the criteria set forth in subdivision (c) of Public Resources Code Section 5024.1, the lead agency shall consider the significance of the resource to a California Native American Tribe.

Less than significant impact with mitigation incorporated. Tribal consultation efforts conducted by the City of Aliso Viejo pursuant to SB 18 and AB 52 to identify TCRs meeting the criteria set forth in Public Resources Code Section 5024.1(c) were initiated on April 24, 2026, when consultation letters were sent to the tribes identified on the NAHC consultation list. The Juaneño Band of Mission Indians, Acjachemen Nation–84A responded on April 24, 2026, and formally requested consultation with the City. The Tribe indicated that it has ancestral and cultural ties to the project area and an interest in protecting and preserving TCRs, sacred sites, and other traditional cultural places within its traditional territory. A consultation meeting between the City and the Tribe was held on May 1, 2026. Following the meeting, the Tribe provided proposed mitigation measures via email on May 5, 2026. On May 8, 2026, the Juaneño Band of Mission Indians, Acjachemen Nation–Belardes also provided proposed mitigation measures for the City's consideration. On August 7, 2026, the City transmitted draft tribal mitigation measures to both consulting tribes for review. On August 8, 2026, the Juaneño Band of Mission Indians, Acjachemen Nation–84A responded, indicating that it had reviewed and generally accepted the City's proposed mitigation measures, while identifying several outstanding questions.

Tribal consultation efforts conducted by the City pursuant to SB 18 and AB 52 are summarized above and informed the development of MM TCR-1 through MM TCR-5. These measures establish 399
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 141
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx procedures for tribal monitoring, the treatment of tribal cultural resources, inadvertent discoveries, and consultation in the event previously unidentified resources are encountered during grounddisturbing activities.

Should any undiscovered TCRs be encountered during project construction, implementation of MM TCR-1 through MM TCR-5 will ensure that potential impacts to TCRs will be reduced to a level of less than significant.

Mitigation Measures
MM TCR-1 Retention of Qualified Archaeologist and Worker Training. Prior to the issuance of a grading permit by the City of Aliso Viejo, evidence shall be provided to the City that a qualified archaeologist meeting the Secretary of the Interior’s Standards for professional archaeology (U.S. Secretary of the Interior 2008) has been retained by the Applicant to conduct any required training, evaluation, or treatment of archaeological resources that might be encountered during implementation of the project.

As part of this, prior to the start of grading, the qualified archaeologist shall conduct cultural resources sensitivity training for all construction personnel. Construction personnel must be informed of the types of archaeological resources that may be encountered (both prehistoric and historical), and of the proper procedures to be enacted in the event of an inadvertent discovery of archaeological resources or human remains. The Applicant must ensure that construction personnel are made available for and attend the training and retain documentation demonstrating attendance. This documentation shall be made available to the City upon request.

MM TCR-2 Native American Monitoring. A Native American monitor from or approved by the project's consulting Tribes (Juaneño Band of Mission Indians Acjachemen Nation – 84A and Juaneño Band of Mission Indians Acjachemen Nation – Belardes) shall be present during all earth-moving construction activities. The Native American monitor shall be given the opportunity to participate in the cultural resource sensitivity training described in the preceding condition of approval. At least 30 days prior to issuance of grading permits by the City for the project site and any off-site improvements, a Native American Monitoring Agreement (Monitoring Agreement) shall be developed between the Applicant and the consulting party. The Monitoring Agreement shall pertain to prehistoric archaeological resources and Tribal Cultural Resources, respectively, and shall identify any monitoring requirements and treatment of cultural resources to meet the requirements of the Tribal representative. The Monitoring Agreement shall also address communication protocols in the event of an unanticipated discovery of cultural materials, and the roles, responsibilities, and authorities of the Native American Monitor. The Monitoring Agreement shall also detail the protocols for treatment and final disposition of any Native American cultural 400
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
142 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx resources, sacred sites, and human remains discovered on the site that the Native American Monitor shall implement in consultation and coordination with the Native American Most Likely Descendant, as identified by the NAHC. In accordance with the condition of approval below, discovery and treatment of human remains shall comply with State Health and Safety Code Section 7050.5 and Public Resources Code (PRC) Section 5097.98.

MM TCR-3 Archaeological Resource and/or Tribal Cultural Resource Discovery and Treatment. In the event of the unanticipated discovery of archaeological or other cultural resources, whether discovered through Native American monitoring or not, all work activities in the area (within approximately 100 feet of the discovery) shall be halted or redirected until the discovery can be evaluated by a qualified archaeologist.

Construction shall not resume until a qualified archaeologist has conferred with the City and, in the case of prehistoric archaeological resources and tribal cultural resources, the Native American monitor, on the significance of the resource. If it is determined that the discovered archaeological resource and/or tribal cultural resource is significant, avoidance and preservation in place shall be the preferred manner of mitigation, pursuant to PRC Section 21083.2(b) and Section 21084.3.

Preservation in place may be accomplished by, but is not limited to, avoidance, incorporating the resource into open space, capping, or deeding the site into a permanent conservation easement. In the event that preservation in place is demonstrated to be infeasible and data recovery through excavation is the only feasible mitigation available, a Treatment Plan shall be prepared and implemented by a qualified archaeologist, in consultation with the City, that provides for the adequate recovery of the scientifically consequential information contained in the archaeological resource or cultural information in the event of a tribal cultural resource. The City and Applicant shall also consult with appropriate Native American representatives in determining treatment for prehistoric or Native American resources to ensure cultural values ascribed to the resources, beyond those that are scientifically important, are considered. Any evaluation and treatment shall be supervised by an individual or individuals that meet the Secretary of the Interior’s Professional Qualification Standards.

MM TCR-4 Treatment of Human Remains. In accordance with California Health and Safety Code Section 7050.5, if human remains are found, the Orange County Sheriff’s Coroner shall be immediately notified of the discovery. No further excavation or disturbance of the site or any nearby area reasonably suspected to overlie adjacent remains (100 feet or as determined by the project archaeologist) shall occur until the procedures set forth in this measure have been implemented. If the County Coroner determines that the remains are, or are believed to be, Native American, the Coroner shall notify the Native American Heritage Commission (NAHC) within 24 hours. In accordance with California PRC Section 5097.98, the NAHC must immediately notify those persons it believes to be the Most Likely Descendant (MLD) from the deceased 401
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 143
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Native American. The MLD shall complete their inspection within 48 hours of being granted access to the site. The designated Native American representative would then determine, in consultation with the property owner, the disposition of the human remains.

MM TCR-5 Native American Monitoring. The project applicant shall retain a Native American Monitor from or approved by the project's consulting Tribes (Juaneño Band of Mission Indians Acjachemen Nation – 84A and Juaneño Band of Mission Indians Acjachemen Nation – Belardes).
(a) The monitor shall be retained prior to the commencement of any “grounddisturbing activity” for the subject project at all project locations (i.e., both on-site and any off-site locations that are included in the project description/definition and/or required in connection with the project, such as public improvement work). “Ground-disturbing activity” shall include, but is not limited to, demolition, pavement removal, potholing, auguring, grubbing, tree removal, boring, grading, excavation, drilling, and trenching.
(b) A copy of the executed monitoring agreement shall be submitted to the lead agency prior to the earlier of the commencement of any ground-disturbing activity, or the issuance of any permit necessary to commence a grounddisturbing activity.

1. Construction coordination meeting shall be conducted prior to start of ground disturbing work (grading, trenching, or excavation) with Qualified Archaeologist, Construction Contractor, Tribal Representative(s).

2. Tribal Cultural Resource Monitoring shall be conducted during all initial ground- disturbing activities until both the Archaeologist and Tribal Monitor determine monitoring is no longer needed. During construction, if cultural materials or features are discovered. Construction contractor, Archaeologist, Tribal Monitor(s) and Lead Agency shall submit a discovery report documenting find, treatment measures, and confirmation that work did not resume until treatment was completed. If human remains are encountered during construction, the construction contractor, County Coroner, NAHC, MLD and Tribal Representative(s) shall follow the following: the coroner shall provide written documentation, the NAHC will be notified, and there shall be confirmation of respectful treatment/reburial as directed by the MLD and Tribe.

3. Qualified Archaeologist and/or Tribal Representative(s) shall submit documentation of recovered materials, correspondence confirming tribal disposition decision (e.g., reburial, return, or other treatment) during and following construction, if artifacts are recovered.

4. Qualified Archaeologist shall submit a Final Monitoring and Mitigation Summary Report and submit to project applicant and appropriate CHRIS repository.
402
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
144 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx

5. Lead Agency, Construction Contractor and or Tribal Representative(s) shall submit records of coordination and confirmation that tribal ceremonies or blessings were accommodated safely and respectfully prior to and/or during construction, as requested by the Tribe.

6. Responsibility for conditions:
a. Lead Agency shall ensure that all measures are implemented, documented and verified prior to and during construction activities; and b. Tribal Participation be a consulting and monitoring partner throughout all ground- disturbing activities; and
c. Compliance Verification shall include documentation of implementation, including monitoring logs, consultation records, and correspondence.

Records shall be maintained in the project file by the Lead Agency. 403
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 145
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.19 Utilities and Service Systems
Would the project:
a) Require or result in the relocation or
construction of new or expanded water,
wastewater treatment or stormwater
drainage, electric power, natural gas, or
telecommunications facilities, the
construction or relocation of which could
cause significant environmental effects?
b) Have sufficient water supplies available
to serve the project and reasonably
foreseeable future development during
normal, dry and multiple dry years?
c) Result in a determination by the
wastewater treatment provider which
serves or may serve the project that it
has adequate capacity to serve the
project’s projected demand in addition
to the provider’s existing commitments?
d) Generate solid waste in excess of State
or local standards, or in excess of the
capacity of local infrastructure, or
otherwise impair the attainment of solid
waste reduction goals?
e) Comply with federal, State, and local
management and reduction statutes
and regulations related to solid waste?
□ □ □
□ □ □
□ □ □
□ □ □
□ □ □
404
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
146 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Evaluation
Setting
This analysis is based in part on the Drainage Report prepared for the proposed project by Advanced Civil Group, Inc., on April 7, 2026, and revised on July 14, 2026. 143
According to the MNWD’s 2020 Urban Water Management Plan (UWMP), MNWD relies on a combination of imported water and recycled water.144 The District’s potable water demands are supplied from imported sources via the Metropolitan Water District of Southern California (Metropolitan) through MWDOC.

Imported water represents approximately 79 percent of MNWD’s total water supply. Metropolitan’s water supply originates from two principal sources—the Colorado River via the Colorado River Aqueduct and the Feather River Watershed/Lake Oroville in Northern California through the State Water Project (SWP). Recycled water provides 21 percent of the district’s water supplies and is produced at one of two local treatment plants.145
The MNWD is responsible for maintenance of the City’s sewer and storm drain lines. Wastewater would be collected via the MNWD’s wastewater collection system and sent to its Regional Treatment Plant in Laguna Niguel.146
Additionally, SoCalGas would provide natural gas service to the project site.147 Telecommunication services would be provided by AT&T and Cox Communications.

Individual trash service would be provided through CR&R Incorporated, with collection occurring on a weekly basis. Waste from the City is disposed of at a number of solid waste facilities, with the majority of waste disposed at the Prima Deshecha Sanitary Landfill.148 143 Advanced Civil Group, Inc. 2026. Drainage Report: Tract No. 19489. Proposed 58-unit Townhome Development Aliso Viejo, California. July 14.
144 Moulton Niguel Water District (MNWD). 2021. Urban Water Management Plan. Website: https://www.mnwd.com/wpcontent/uploads/2021/06/2020-Urban-Water-Management-Plan_Adopted.pdf. Accessed April 10, 2026. 145 Ibid.
146 Moulton Niguel Water District (MNWD). 2026. Wastewater Collection and Treatment. Website:
https://www.mnwd.com/wastewater-treatment/. Accessed April 10, 2026. 147 Southern California Gas (SoCalGas). 2026. About Us. Website: https://www.socalgas.com/about-us. Accessed April 10, 2026.
148 California Department of Resources Recycling and Recovery (CalRecycle). 2026. RDRS Report 2: Jurisdiction Disposal and Beneficial Reuse by Destination. Website:
https://www2.calrecycle.ca.gov/RecyclingDisposalReporting/Reports/JurisdictionDisposalAndBeneficial. Accessed April 10, 2026.
405
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 147
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Would the project:
a) Require or result in the relocation or construction of new or expanded water, wastewater treatment or stormwater drainage, electric power, natural gas, or telecommunications facilities, the construction or relocation of which could cause significant environmental effects?
Less than significant impact.

Water
The proposed project would include water lines throughout the project site that would connect to existing water lines within Argonaut. As such, the existing water lines within Argonaut that connect to MNWD water services would sufficiently serve the proposed project. Impacts related to the construction of infrastructure improvements have been addressed throughout this Draft IS/MND and would be reduced through the implementation of all mitigation measures included in this Draft IS/MND. Therefore, the proposed project would not require and would not result in the construction of new water facilities or expansion of existing water facilities. Impacts would be less than significant.

Wastewater
Wastewater would be collected via the MNWD’s wastewater collection system and sent to its Regional Treatment Plant in Laguna Niguel.149 The proposed project would connect to existing sanitary sewer lines in Argonaut. As described under Impact 2.19(c) below, MNWD treats more than 10 MGD, and has sufficient capacity to accommodate wastewater generated by the proposed project.

The proposed project is estimated to result in approximately 16,008.3 total gallons of wastewater a day, which is approximately 0.06 percent of MNWD’s daily capacity, which is a nominal amount.

Therefore, the proposed project would not require or result in relocation or construction of wastewater facilities, the construction or relocation of which could cause significant environmental effects.

Stormwater
The proposed project would include an on-site stormwater collection system consisting of catch basins, underground storm drain lines, and water quality treatment facilities designed to convey and manage runoff generated by the proposed project. Runoff would be collected from rooftops, drive aisles, parking areas, and landscaped areas and directed through the proposed drainage system prior to discharge to the existing public storm drain network. As further discussed in Section 2.10, Hydrology, the proposed project would be designed consistent with the approved drainage plan and would not exceed the capacity of the existing stormwater drainage system. The potential environmental effects associated with construction and operation of the proposed project, including the proposed stormwater facilities to serve the residential units are analyzed within this Initial Study and impacts have been determined to be less than significant with compliance with regulatory 149 Moulton Niguel Water District (MNWD). 2026. Wastewater Collection and Treatment. Website:
https://www.mnwd.com/wastewater-treatment/. Accessed April 10, 2026. 406
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
148 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx requirements and implementation of mitigation measures. As such, impacts would be less than significant.

Electric Power and Natural Gas
The project site is currently served by electrical and gas infrastructure associated with the existing office building. The proposed project would connect to existing electrical infrastructure. Natural gas would be provided by SoCalGas. Electrical service is currently available in the project area and would be provided by SCE. Electricity would connect to existing underground utility lines running within Argonaut and would not cause significant environmental effects. Impacts associated with the proposed project’s electricity demand and natural gas demand are discussed previously in Section

2.6, Energy.

Telecommunications
The project site is currently fully developed and served by telecommunications infrastructure. The proposed project would connect to the existing telecommunications infrastructure. Therefore, the proposed project would not require the installation or development of new or improved telecommunications facilities such that environmental impacts would occur. Impacts would be less than significant.
b) Have sufficient water supplies available to serve the project and reasonably foreseeable future development during normal, dry and multiple dry years? Less than significant impact. As discussed above, the proposed project would connect to the existing water lines and system. The 2020 UWMP includes a supply and demand assessment for projected years between 2025 and 2045 for normal year, single dry year, and multiple dry year scenarios. Table 12, below, shows the multiple-dry year supply and demand comparison through 2045.

Table 12: Multiple Dry Year Supply and Demand Comparison (AFY) 2025 2030 2035 2040 2045
First year
Supply totals 33,435 33,111 32,934 32,790 32,588
Demand totals 33,435 33,111 32,934 32,790 32,588
Difference 0 0 0 0 0
Second year
Supply totals 33,419 33,124 32,953 32,797 32,636
Demand totals 33,419 33,124 32,953 32,797 32,636
Difference 0 0 0 0 0
Third year
Supply totals 31,969 31,714 31,556 31,396 31,280
Demand totals 31,969 31,714 31,556 31,396 31,280
Difference 0 0 0 0 0
407
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 149
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx 2025 2030 2035 2040 2045
Fourth year
Supply totals 31,906 31,680 31,529 31,357 31,280
Demand totals 31,906 31,680 31,529 31,357 31,280
Difference 0 0 0 0 0
Fifth year
Supply totals 31,844 31,646 31,501 31,319 31,280
Demand totals 31,844 31,646 31,501 31,319 31,280
Difference 0 0 0 0 0
Source: Moulton Niguel Water District (MNWD). 2021 (MNWD). 2020 Urban Water Management Plan. Website:
https://www.mnwd.com/wp-content/uploads/2021/12/2020-Urban-Water-Management-Plan.pdf. Accessed April 10, 2026.

The demands are expected to be met through a combination of imported and recycled water. MNWD works together with two primary agencies, MWDOC and Metropolitan, to ensure a safe and reliable water supply that would serve the community in periods of drought and shortage.150 The UWMP accounts for projected water demand based on water consumption by single- and multi-family residences, commercial, and institutional/government customers.151 The UWMP also accounts for projected land use, population, economic growth, and future conservation.152 As noted in the UWMP and as shown in Table 12, the City would have sufficient water supplies for normal year, single dry year, and multiple dry years.

According to the DOF, the City has an average of 2.53 persons per household.153 The proposed project would include the construction of up to 58 3-story townhomes, which would increase the City’s population by up to 147 persons based on the average household size.154 As discussed in Section

2.14, Population and Housing, this population growth is considered planned growth under SCAG’s predictions. MNWD’s 2020 actual consumption was 121 gallons per capita per day (GPCD). For the estimated 147 residents under the proposed project, this would result in an estimated water demand of approximately 17,787 gallons per day (GPD) or 19.9 AFY. As noted in the UWMP, the projected normal year water use in 2030 is 31,782 AFY.155 The proposed project’s demand would be approximately 0.06 percent of the total projected normal year 2030 demand. The UWMP also notes that during the fifth year of the multiple dry year scenario, the projected water demand and supply would be 31,646 AFY. The proposed project’s demand would be approximately 0.06 percent of the 150 Moulton Niguel Water District (MNWD). 2021. 2020 Urban Water Management Plan. Website:
https://www.mnwd.com/wp-content/uploads/2021/12/2020-Urban-Water-Management-Plan.pdf. Accessed April 10, 2026. 151 Ibid.
152 Moulton Niguel Water District (MNWD). 2021. 2020 Urban Water Management Plan. Website:
https://www.mnwd.com/wp-content/uploads/2021/12/2020-Urban-Water-Management-Plan.pdf. Accessed April 10, 2026. 153 California Department of Finance (DOF). 2026. E-5 City/County Population and Housing Estimates for Cities, Counties, and the State, 2020-2025. Website: https://dof.ca.gov/forecasting/demographics/estimates/e-5-population-and-housingestimates-for-cities-counties-and-the-state-2020-2026/. Accessed May 12, 2026. 154 2.53 persons per household * 58 residential units= 146.74 persons, or approximately 147 persons. 155 Moulton Niguel Water District (MNWD). 2021. 2020 Urban Water Management Plan. Website:
https://www.mnwd.com/wp-content/uploads/2021/12/2020-Urban-Water-Management-Plan.pdf. Accessed April 10, 2026. 408
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
150 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx total projected fifth multiple dry year demand. Additionally, water demand for the proposed project is partially offset by the existing water demand on-site currently used for landscaping and to service the existing office building. Therefore, the projected water use of the proposed project would be nominal, and water supplies would be sufficient to continue serving the project site. As such, the proposed project would not significantly impact water supplies. Impacts would be less than significant. c) Result in a determination by the wastewater treatment provider which serves or may serve the project that it has adequate capacity to serve the project’s projected demand in addition to the provider’s existing commitments? Less than significant impact. As discussed above, the proposed project would connect to existing sanitary sewer lines. The MNWD is responsible for the City’s sewer lines. The MNWD collects and treats more than 10 million gallons of wastewater per day from residential and commercial customers throughout the district’s service area. MNWD utilizes three different treatment plants to appropriately treat the wastewater, with two of those treatment plants equipped to produce recycled water. The 3A Treatment Plant in Mission Viejo is owned and operated by MNWD and has a capacity of 6 million GPD. The Regional Treatment Plant in Laguna Niguel is currently operated by a regional operator, South Orange County Wastewater Authority (SOCWA), but is also home to the largest recycled water facility that is owned and operated by MNWD. The Regional Treatment Plant has a capacity of 9.4 million GPD. Additionally, the J.B. Latham Treatment Plant in Dana Point, which is also operated by SOCWA, provides an additional facility for treatment of wastewater and has a capacity of 13 million GPD.156 Any treated wastewater that cannot be utilized for irrigation purposes is then discharged to the ocean through one of two ocean outfalls, the Aliso Creek Ocean Outfall and the San Juan Creek Ocean Outfall. The MNWD works closely with SOCWA, as the regional permitting entity, and the appropriate regulatory agencies to ensure that all treated wastewater, whether used for irrigation purposes or discharged to the ocean, is compliant with all regulatory requirements.157 A Municipal Service Review was prepared for the Southwest Region of Orange County in 2023, which included a review of the MNWD.158 The purpose of the review was in part—to review and study future growth in the service area and to determine whether Southwest Region of Orange County can efficiently, equitably, and reliably provide services. The review determined that MNWD existing and planned operations and infrastructure can meet current and future service demands.159 The proposed project would result in approximately 16,008.3 total gallons of wastewater per day, which is equivalent to 0.016 million gallons per day (MGD).
160 Based on a total combined wastewater treatment capacity of 28.4 MGD, the proposed project’s wastewater generation would be approximately 0.06 percent of the total daily capacity, which is a nominal amount. Furthermore, the proposed project’s expected 156 Moulton Niguel Water District (MNWD). 2026.Wastewater Collection and Treatment. Website: https:// www.mnwd.com/wastewater-treatment/. Accessed April 10, 2026. 157 Ibid.
158 Orange County Local Agency Formation Commission (Orange County LAFCo). 2023. Municipal Service Review and Sphere of Influence Reviews. August 9. Website: https:// oclafco.org/wpcontent/uploads/2024/01/OCLAFCO_Southwest_MSR_-_Final_8.28.23.pdf. Accessed April 10, 2026. 159 Ibid.
160 Based on the assumption that wastewater generated is approximately 90 percent of indoor water use. 409
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 151
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx wastewater generation would be partially offset by the existing wastewater generated and treated from the on-site office building. Therefore, MNWD would have adequate capacity to continue serving the project site and the wastewater demands of the proposed project, and impacts would be less than significant.
d) Generate solid waste in excess of State or local standards, or in excess of the capacity of local infrastructure, or otherwise impair the attainment of solid waste reduction goals?
Less than significant impact. Construction and operational activities associated with the proposed project would generate solid waste requiring disposal. CR&R Incorporated is a private recycling and nonhazardous solid waste hauler and provides solid waste services to the City, including the project site.161 CR&R Incorporated collects solid waste for all residential, commercial, and industrial waste and recycling services. Solid waste is disposed of in Orange County landfills.

Solid waste within the City is primarily disposed of at the Prima Deshecha Sanitary Landfill. Other sanitary landfills, including Chiquita Canyon, El Sobrante, Frank R. Bowerman, Simi Valley, and Olinda Alpha received relatively small amounts of solid waste from the City. The Prima Deshecha Landfill is the closest facility to the City and would likely be the solid waste facility most often receiving waste from the project site.162 According to the California Department of Resources Recycling and Recovery (CalRecycle) Solid Waste Information System (SWIS), the Prima Deshecha Landfill has a maximum daily capacity of 4,000 tons per day and a remaining capacity of 128,800,000 cubic yards.

The facility’s maximum permitted capacity is 172,100,000 cubic yards.163 CalRecycle provides a solid waste generation factor to estimate the amount of solid waste generated by residential projects. Using the generation rate of 12.23 pounds (lbs) per household per day for residential development164, the proposed project would generate approximately 709.34 lbs per day of solid waste, or approximately 0.35 tons per day (based on 58 townhomes)—which represents less than 0.01 percent of the maximum daily capacity of the Prima Deshecha Sanitary Landfill.

Therefore, the Prima Deshecha Landfill would have sufficient capacity to serve the proposed project and solid waste generated during construction and operations would represent a negligible increase compared to the daily permitted tonnage. Furthermore, under existing conditions, the project site generates solid waste associated with the existing office building. The proposed project would continue to be served by the same solid waste collection services and therefore, the expected solid waste generation from the proposed project is partially offset by the existing office use currently occupying the project site. The proposed project would also include recycling, reuse, and/or salvage 161 City of Aliso Viejo. 2025. Services. Website: https://avcity.org/101/Services. Accessed April 10, 2026. 162 California Department of Resources Recycling and Recovery (CalRecycle). 2024. SWIS Facility/Site Activity Details.

Website: https:// www2.calrecycle.ca.gov/SolidWaste/SiteActivity/Details/2750?siteID=2085. Accessed April 10, 2026. 163 Ibid.
164 California Department of Resources Recycling and Recovery (CalRecycle). 2026. Residential Sector Generation Rates.

Website: https://www2.calrecycle.ca.gov/wastecharacterization/general/rates. Accessed April 10, 2026. 410
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
152 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx programs to reduce solid waste and comply with all applicable regulations for solid waste. Impacts would be less than significant.
e) Comply with federal, State, and local management and reduction statutes and regulations related to solid waste?
Less than significant impact. The City complies with all federal, State, and local statutes and regulations related to solid waste. Regulations specifically applicable to the proposed project include the California Integrated Waste Management Act of 1989 (AB 939), SB 2202, SB 1016, 2019 CALGreen Section 4.408, SB 1383, and AB 341, which requires multfamily residential development and commercial uses to implement recycling programs.

In accordance with State law and Municipal Code Section 13.02, Building Regulations, which adopts CALGreen, the proposed project would be required to divert at least 65 percent of the nonhazardous construction and demolition debris from the project site by recycling, reuse, and/or salvage. In addition, Municipal Code Chapter 7.05, Solid Waste Disposal, addresses solid waste disposal, including recycling and organic waste. Compliance with the Municipal Code would achieve compliance with State law, including SB 1383.

The City has a per capita population disposal rate target of 3.3 pounds per person per day and a per capita employment disposal rate of 9.4 pounds per person per day. Since 2007, the City has met these targets through its diversion programs. The most recent population disposal rate (2024) was

3.5 pounds per day per capita for population and 8.9 pounds per day per capita for employment.165 Therefore, although the City met its disposal rate target for per capita employment disposal, it slightly exceeded its target for per capita disposal rates. It should be noted that this minor exceedance represents a small, short-term fluctuation, and does not reflect a failure to implement diversion programs. The City would continue to implement its diversion programs and requires compliance with all federal, State, and local statutes and regulations for solid waste, including those identified under the most current CALGreen standards and in compliance with SB 1383.

In 1989, the Legislature adopted AB 939, in order to “reduce, recycle, and reuse solid waste generated in the State to the maximum extent feasible.” AB 939 established a waste management hierarchy and required that each county prepare a new Integrated Waste Management Plan and each City prepare a Source Reduction and Recycling Element (SRRE) by July 1, 1991. The SRRE was required to identify how each jurisdiction would meet the mandatory State waste diversion goal of 50 percent by and after the year 2000.

SB 2202 made a number of changes to the municipal solid waste diversion requirements under AB 939. These changes included a revision to the statutory requirement for 50 percent diversion of solid waste to clarify that local governments shall continue to divert 50 percent of all solid waste on and after January 1, 2000.
165 California Department of Resources Recycling and Recovery (CalRecycle), Jurisdiction Per Capita Disposal Rate Trends. Website: https://www2.calrecycle.ca.gov/LGCentral/AnnualReporting/ReviewReports. Accessed April 10, 2026. 411
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 153
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx SB 1016 introduced a per capita disposal measurement system that measures the 50 percent diversion requirement using a disposal measurement equivalent. SB 1016 repealed the prior 2-year process, requiring instead that CalRecycle to make a finding whether each jurisdiction was in compliance with the Act’s diversion requirements for calendar year 2006 and determine compliance for the 2007 calendar year and beyond based on the jurisdiction’s change in its per capita disposal rate. CalRecycle is required to review a jurisdiction’s compliance with those diversion requirements in accordance with a specified schedule, which is conditioned upon the CalRecycle finding that the jurisdiction complies with those requirements or has implemented its SRRE and household hazardous waste element. SB 1016 requires CalRecycle to issue an order of compliance if it is determined that the jurisdiction has failed to make a good faith effort to implement its SRRE or its household hazardous waste element, pursuant to a specified procedure. The per capita disposal rate is a jurisdiction-specific index, which is used as one of several “factors” in determining a jurisdiction’s compliance with the intent of AB 939 and allows CalRecycle and jurisdictions to set their primary focus on successful implementation of diversion programs.

SB 1383 requires counties to take the lead in collaborating with jurisdictions located within the county in planning for the necessary organic waste recycling and food recovery capacity needed to divert organic waste from landfills into recycling activities and food recovery organizations.

CALGreen Section 4.408 requires preparation of a Construction Waste Management Plan that provides an overview of ways in which the applicant would recycle and/or salvage for reuse a minimum of 65 percent of the nonhazardous construction and demolition debris. As discussed above, during the construction phase, the proposed project would be required to comply with CALGreen through the recycling and reuse of at least 65 percent of the nonhazardous construction and demolition debris from the project site.

Participation in the City’s recycling programs during project construction and operation, including CalRecycle’s requirements, would ensure that the proposed project would not conflict with federal, State, and local statutes and regulations related to solid waste. Additionally, solid waste would be disposed of at existing Orange County Waste and Recycling landfills. Disposal of solid waste would comply with all federal, State, and local statutes and regulations related to solid waste. During operation, the proposed project would include receptacles for recyclables and garbage. Furthermore, the existing office use on-site complies with all aforementioned statutes and regulations related to solid waste. Therefore, continued and ongoing compliance with federal, State, and local mandates related to solid waste generated by the proposed project would reduce impacts on applicable federal, State, and local mandates related to solid waste to less than significant. Thus, impacts would be less than significant, and no mitigation is required.

Mitigation Measures
None required.
412
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
154 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.20 Wildfire
If located in or near State Responsibility Areas or lands classified as very high fire hazard severity zones, would the project:
a) Substantially impair an adopted
emergency response plan or
emergency evacuation plan?
b) Due to slope, prevailing winds, and
other factors, exacerbate wildfire risks,
and thereby expose project occupants
to, pollutant concentrations from a
wildfire or the uncontrolled spread of a
wildfire?
c) Require the installation or maintenance
of associated infrastructure (such as
roads, fuel breaks, emergency water
sources, power lines or other utilities)
that may exacerbate fire risk or that may
result in temporary or ongoing impacts
to the environment?
d) Expose people or structures to
significant risks, including downslope or
downstream flooding or landslides, as a
result of runoff, post-fire slope instability,
or drainage changes?
Environmental Evaluation
Setting
The CAL FIRE FHSZ Map indicates the project site is not within a State Responsibility Area (SRA).

The closest SRA is located approximately 1.3 miles west of the project site, in the Aliso and Wood Canyons Wilderness Park. No part of the City is listed as an SRA. 166
166 California Department of Forestry and Fire Protection (CAL FIRE). 2026. Fire Hazard Severity Zones. Website:
□ □ □
□ □ □
□ □ □
□ □ □
413
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 155
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx VHFHSZs are located along the southern and western boundaries of the City.167 The General Plan indicates that the closest VHFHSZ is located near Aliso Creek Road, 0.82 mile west of the project site.168
Would the project:
a) Substantially impair an adopted emergency response plan or emergency evacuation plan?
No impact. The project site is developed and located within an urbanized area with existing infrastructure. According to the CAL FIRE FHSZ Map, the project site is not located within a VHFHSZ, nor is it within or near an SRA. Additionally, the proposed project would comply with all City and OCFA requirements for fire prevention and safety measures, including adequate site access.

The City is divided into 22 all-hazard evacuation zones. The project site is within Zone 20 of Aliso Viejo’s Evacuation Zones. Designated evacuation zones within Zone 20 include Glenwood Drive, Aliso Creek Road, Aliso Viejo Parkway, and Moulton Parkway.169 As previously mentioned under Impact 2.9(f), the project site is adjacent to both Glenwood Drive and Aliso Creek Road, which would be accessible via the project site’s access driveway on Argonaut, and construction would not require closure or partial closure of Glenwood Drive or Aliso Creek Road. The proposed project would be constructed completely within the project site and construction equipment would access the project site via Argonaut, which is the main access point to the project site. If any road closures to Argonaut are required, the project applicant and construction crew would be required to coordinate with the City of Aliso Viejo Public Works Department to ensure that emergency access routes are maintained during construction. Thus, construction of the proposed project would not impede the use of surrounding roadways for emergencies or access for emergency response vehicles.

The proposed project would have access to several different emergency evacuation routes as shown on the evacuation zone maps and would not impair access to any of these emergency evacuation routes. Furthermore, the proposed project would not interfere with the evacuation plan or evacuation routes identified in the City’s EOP and the General Plan Safety Element (see Impact 2.9(f)).

Therefore, the proposed project would not conflict with any adopted emergency response or evacuation plans. No impact related to emergency response or evacuation plans would occur. https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones.

Accessed April 10, 2026.
167 City of Aliso Viejo. 2004. General Plan Figure S-1 Safety Policy Map. Website:
https://www.avcity.org/DocumentCenter/View/384/Safety-Policy-Map-PDF. Accessed April 1, 2026. 168 Ibid.
169 City of Aliso Viejo. 2024. Citywide Evacuation Zones. Website: https://avcity.org/DocumentCenter/View/3750. Accessed April 1, 2026.
414
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
156 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx b) Due to slope, prevailing winds, and other factors, exacerbate wildfire risks, and thereby expose project occupants to, pollutant concentrations from a wildfire or the uncontrolled spread of a wildfire?
Less than significant impact. The project site is developed and located within an urbanized area with existing infrastructure. According to the most recent CAL FIRE maps, the project site is not located within a FHSZ170 and the project site does not have a history of wildfires.171 Although the topography of the project site is relatively flat, the existing northern and western slopes of the project site would be preserved along with the existing screening trees as part of the proposed project.

Therefore, the proposed project would be largely buffered from prevailing northeasterly winds that would exacerbate fire risk. Furthermore, the proposed project would implement all applicable fire prevention standards and would thus not exacerbate fire risk, and the proposed project would install a slope maintenance easement along the toe of the slope along the northern and western boundaries of the development footprint to ensure ongoing maintenance and preservation of the slope in order to prevent wildfire risks. Thus, the proposed project would not exacerbate fire risk from existing conditions, and impacts would be less than significant. c) Require the installation or maintenance of associated infrastructure (such as roads, fuel breaks, emergency water sources, power lines or other utilities) that may exacerbate fire risk or that may result in temporary or ongoing impacts to the environment?
No impact. The proposed project does not include infrastructure improvements, such as roads, fuel breaks, emergency water sources, or new utility installations, that could exacerbate fire risk. The site is already developed with existing infrastructure in place. Compliance with fire safety standards and coordination with the OCFA ensures no additional infrastructure would create new fire risks or result in temporary or ongoing environmental impacts. Additionally, the proposed project would install one fire hydrant consistent with fire flow requirements in accordance with California Fire Code guidelines stipulated in Municipal Code Chapter 13.04 and would connect to existing water lines. Installation of this fire hydrant would not exacerbate any fire risks but would assist the City in preparing for and addressing potential fires.

The proposed internal roadways would be designed to allow for adequate emergency access, and a fire hydrant would be provided, consistent with California Fire Code fire flow requirements on-site.

Through compliance with all applicable fire safety regulations for fire prevention and emergency access, the proposed project would not exacerbate fire risk from existing conditions. Therefore, there would be no impact.
170 California Department of Forestry and Fire Protection (CAL FIRE). 2026. Fire Hazard Severity Zones. Website:
https://osfm.fire.ca.gov/what-we-do/community-wildfire-preparedness-and-mitigation/fire-hazard-severity-zones.

Accessed April 10, 2026.
171 California Department of Forestry and Fire Protection (CAL FIRE). 2024. California Wildfire History Map. Website: https:// projects.capradio.org/california-fire-history/#10.64/33.5901/-117.7005. Accessed April 10, 2026. 415
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 157
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx d) Expose people or structures to significant risks, including downslope or downstream flooding or landslides, as a result of runoff, post-fire slope instability, or drainage changes?
Less than significant impact. Although the sloped areas along the northern and western boundaries of the project site are mapped as having landslide potential by General Plan Figure S-1, Safety Policy Map, the proposed project would be required to incorporate the site-specific recommendations from the Geotechnical Investigation in accordance with Municipal Code Chapter 13.08.170 and to incorporate additional recommendations to address landslide susceptibility. Through implementation of these recommendations as COA GEO-1a and COA GEO-1b, the proposed project would ensure that slopes are maintained over the life of the project and would establish minimum setback criteria for descending slopes. Implementation of COA GEO-1a would reduce the potential for landslide hazards by incorporating site-specific design recommendations into project construction plans and grading plans related to slope stability. Implementation of COA GEO-1b would require grading activities adjacent to the existing slopes along the western and northern boundaries of the site to be observed by a licensed California Geotechnical Engineer or Certified Engineering Geologist. COA GEO-1b would ensure that, if necessary, supplemental recommendations would be incorporated into construction and grading plans to address potential impacts related to landslide susceptibility.

Furthermore, the project site and surrounding areas do not have a history of wildfires and would not include changes to drainage patterns that could increase risks of flooding or slope instability.

Compliance with existing stormwater and drainage regulations would further prevent any related risks. Through application of project-specific recommendations in accordance with the recommendations of the Geotechnical Investigation and local regulations, the proposed project would not expose people to significant risks as a result of post-fire slope instability or drainage changes.

Therefore, impacts would be less than significant.

Mitigation Measures
None required.
416
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
158 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Issues
Potentially
Significant
Impact
Less than
Significant
Impact with
Mitigation
Incorporated
Less than
Significant
Impact No Impact

2.21 Mandatory Findings of Significance
a) Does the project have the potential to
substantially degrade the quality of the
environment, substantially reduce the
habitat of a fish or wildlife species,
cause a fish or wildlife population to
drop below self-sustaining levels,
threaten to eliminate a plant or animal
community, substantially reduce the
number or restrict the range of a rare or
endangered plant or animal, or
eliminate important examples of the
major periods of California history or
prehistory?
b) Does the project have impacts that are
individually limited, but cumulatively
considerable? (“Cumulatively
considerable” means that the
incremental effects of a project are
considerable when viewed in
connection with the effects of past
projects, the effects of other current
projects, and the effects of probable
future projects)
c) Does the project have environmental
effects, which will cause substantial
adverse effects on human beings, either
directly or indirectly?
□ □ □
□ □ □
□ □ □
417
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 159
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx Environmental Evaluation
a) Does the project have the potential to substantially degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, substantially reduce the number or restrict the range of a rare or endangered plant or animal, or eliminate important examples of the major periods of California history or prehistory?
Less than significant impact with mitigation incorporated. As discussed throughout this document, the proposed project does not have the potential to substantially degrade the quality of the environment or result in significant environmental impacts that cannot be mitigated or reduced to a less than significant level through compliance with the established regulatory framework and implementation of mitigation measures.

As demonstrated in Section 2.4, Biological Resources, the proposed project would not substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below selfsustaining levels, threaten to eliminate a plant or animal community, or substantially reduce the number or restrict the range of a rare or endangered plant or animal. The proposed project would be required to comply with the MBTA and other applicable regulations and to implement MM BIO-1a and MM BIO-1b, which require a pre-construction survey and avoidance of direct and indirect impacts on active nests. Implementation of these measures would reduce potential impacts to a less than significant level. Furthermore, the proposed project would not conflict with habitat because it does not contain Covered Habitats or suitable habitat for Identified Species covered under the CONCCP/HCP.

As demonstrated in Section 2.5, Cultural Resources, the proposed project would not eliminate important examples of the major periods of California history or prehistory. As concluded in Section

2.5, the proposed project would not result in significant adverse impacts to archaeological resources, TCRs, or human remains. MM CUL-1 would require WEAP training, a site survey conducted by a qualified Archaeologist, and archaeological monitoring. MM CUL-2 would require consultation with a qualified Archaeologist in the event that buried archaeological resources are discovered during construction, as well as inadvertent discovery procedures. MM CUL-3 would require specific procedures to be followed related to inadvertent discovery of human remains. Therefore, the proposed project would not degrade the quality of the environment, substantially reduce the habitat of a fish or wildlife species, cause a fish or wildlife population to drop below self-sustaining levels, threaten to eliminate a plant or animal community, substantially reduce the number or restrict the range of a rare or endangered plant or animal, or eliminate important examples of the major periods of California history or prehistory.

As demonstrated in Section 2.18, Tribal Cultural Resources, the proposed project would not cause a substantial adverse change in the significance of a TCR, defined in Public Resources Code Section 21074. However, as concluded in Section 2.18, the proposed project’s NAHC SLF results were positive for TCRs on the project site, and subsequent Tribal outreach to obtain additional information pertaining to TCRs within the project site produced negative results. However, should any 418
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
160 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx undiscovered TCRs be encountered during project construction, implementation of MM TCR-1 through MM TCR-5 as described above would reduce impacts to a less than significant level. b) Does the project have impacts that are individually limited, but cumulatively considerable? (“Cumulatively considerable” means that the incremental effects of a project are considerable when viewed in connection with the effects of past projects, the effects of other current projects, and the effects of probable future projects)?
Less than significant impact with mitigation incorporated. A significant cumulative impact may occur if a project, in conjunction with related projects, would result in impacts that are less than significant when viewed individually but would be cumulatively significant when viewed together.

Table 13 lists the development projects that have been proposed within the City. The nearest project is approximately 500 feet from the proposed project. Based on available information, there are no approved projects or projects currently under construction in the project’s surrounding area at this time, nor are there any that would have a construction schedule that would overlap with the proposed project.172 The projects were reviewed to identify whether the proposed project would contribute to cumulatively significant impacts when evaluated in combination with other projects.

Table 13: Current Projects in the Vicinity of the Proposed Project Project Type Location Distance Description Status
City of Aliso Viejo1
Residential 95 Argonaut 0.10 mile Demolition of existing office building to accommodate the construction of
61 3-story townhomes.

Under review
Residential 27081 Aliso Creek
Road

1.65 miles Demolition of three existing office
buildings and construction of a 137-
unit, residential community.

Under review
Residential 26800–26970 Aliso
Viejo Parkway

1.36 miles Demolition of five 2-story office
buildings to accommodate the
construction of 215 residential units.

Under review
Residential 400–600 Freedom
Lane

2.16 miles Construction of a 134-unit residential
community.

Under review
Mixed Use 26501 Aliso Creek
Road

0.90 mile Construction of a mixed-use building
with 17,273 square feet of ground
floor commercial space with 343
residential units above.

Under review
Notes:
1 City of Aliso Viejo. Major Projects. Website: https://avcity.org/412/Major-Projects. Accessed May 11, 2026. 172 City of Aliso Viejo. Major Projects. Website: https://avcity.org/412/Major-Projects. Accessed May 11, 2026. 419
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
FCS 161
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx When considering the proposed project in combination with other past, present, and reasonably foreseeable future projects in the vicinity of the project site, it is reasonably assumed, consistent with CEQA practice, that all cumulative development projects would be required to comply with applicable federal, State, and local regulations, performance standards, and environmental review requirements intended to avoid or reduce environmental impacts. Within this regulatory framework, past, present, and reasonably foreseeable future projects in the area consist primarily of infill or small-scale development and would not combine with the proposed project to create related or compounding environmental effects. Accordingly, the cumulative environmental setting would remain at less than significant levels with implementation of the proposed project.

Moreover, the proposed project does not result in environmental impacts that would incrementally contribute to a significant cumulative impact. The proposed project’s impacts would be individually limited and not cumulatively considerable. The proposed project could result in potentially significant impacts related to biological resources, cultural resources, paleontological resources, and hazards and hazardous materials. However, these impacts would primarily be related to construction period activities, would be temporary in nature, and would not substantially contribute to any potential cumulative impacts associated with these topics. As there are no cumulative projects that would be undergoing construction simultaneously with the proposed project, less than significant cumulative impacts are anticipated.

Specifically, since the proposed project would not exceed South Coast AQMD thresholds of significance related to air quality, the proposed project would not result in a cumulatively considerable net increase of construction emissions, operational emissions, or TACs. As discussed more fully in Section 2.8 of this IS/MND, GHG emissions-related impacts are inherently cumulative in nature. The proposed project also would not conflict with any applicable GHG plan, policy, or regulation adopted for the purpose of reducing the emissions of GHGs. As such, the proposed project, in conjunction with other existing, planned, and probable foreseeable projects, would not result in a significant cumulative impact related to GHG emissions generation. As for transportation and traffic impacts, construction of the proposed project would have the potential for temporary impacts to road hazards and emergency access. Use of local roads for transport of construction equipment and construction personnel would be temporary and short-term. Given the location of the project area in relation to other development projects in the region, the transportation network is sufficient to accommodate construction traffic to avoid significant impacts to any one area. Transportation and traffic impacts would be temporary and less than significant, and would not contribute to cumulatively considerable impacts.

Furthermore, compliance with the regulatory requirements and implementation of mitigation measures at the project level would reduce the potential for incremental effects that would occur with construction and operation of the proposed project relevant to the environmental topical areas discussed within this document to below a level of significance. The mitigation measures identified in this document, including MM BIO-1a, MM BIO-1b, MM CUL-1, MM CUL-2, MM CUL-3, MM GEO-1, MM HAZ-1, MM TCR-1, MM TCR-2, MM TCR-3, MM TCR-4, and MM TCR-5 would reduce the proposed project’s incremental contribution to any potential cumulative impacts to below a level of 420
15 ARGONAUT PROJECT

INITIAL STUDY/MITIGATED NEGATIVE DECLARATION
162 FCS
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx significance. No additional mitigation measures would be required to address cumulative impacts.

Therefore, the proposed project would cause less than significant cumulative impacts. c) Does the project have environmental effects, which will cause substantial adverse effects on human beings, either directly or indirectly? Less than significant impact with mitigation incorporated. The proposed project would improve the housing stock in the City. Based on the discussion provided in the Project Description and the analysis presented in Sections 2.1 through 2.20 of this document, the proposed project would not cause substantial adverse effects on human beings, either directly or indirectly, because the proposed project’s potential impacts would be mitigated to a less than significant level. Therefore, with implementation of MM BIO-1a, MM BIO-1b, MM CUL-1, MM CUL-2, MM CUL-3, MM GEO-1, MM HAZ-1, MM TCR-1, MM TCR-2, MM TCR-3, MM TCR-4, and MM TCR-5. The proposed project would not result in substantial adverse effects on human beings. Impacts would be less than significant with mitigation incorporated.

Mitigation Measures
Implement MM BIO-1a, MM BIO-1b, MM CUL-1, MM CUL-2, MM CUL-3, MM GEO-1, MM HAZ-1, MM TCR-1, MM TCR-2, MM TCR-3, MM TCR-4, and MM TCR-5.
421
15 Argonaut Project
Initial Study/Mitigated Negative Declaration
FCS 163
Https://adecinnovations.sharepoint.com/sites/PublicationsSite/Shared Documents/Publications/Client (PN-JN)/6513/65130001/ISMND/65130001 Aliso Viejo 15 Argonaut Project Draft ISMND.docx 3 - LIST OF PREPARERS
FirstCarbon Solutions
250 Commerce, Suite 210
Irvine, CA 92602
Phone: 714.508.4100
Project Director.........................................................................................................................Cecilia So Project Manager .............................................................................................................................Tsui Li Assistant Project Manager..........................................................................................Regan Del Rosario Analyst ................................................................................................................................. Heather Carr Legal Counsel....................................................................................................................... Megan Starr Director of Cultural Resources ....................................................................... Dana DePietro, PhD, RPA Director of Noise and Air Quality ............................................................................. Phil Ault, LEED® AP Biologist .................................................................................................................................. Kyle Killian Senior Managing Editor........................................................................................................ Susie Harris Publications Manager............................................................................................................. Alec Harris Technical Editor ...................................................................................................................... Sarah Vine Technical Document Manager....................................................................................... Melissa Ramirez GIS/Graphics .............................................................................................................. Karlee McCracken GIS/Graphics ................................................................................................................Sebastian Macias Stantec Consulting Services, Inc.–Technical Subconsultant Phase I ESA and Phase II ESA 38 Technology Drive West, Suite 200
Irvine, CA 92618
949.923.6000
Alta Geotechnical, Inc.–Technical Subconsultant Geotechnical 170 North Maple Street, Suite 108
Corona, CA 92878
951.509.7090
Advanced Civil Group, Inc.–Technical Subconsultant Hydrology 30251 Golden Lantern
Laguna Niguel, CA 92677
866.338.5778
Urban Crossroads, Inc.–Technical Subconsultant Transportation 260 East Baker Street, Suite 200
Costa Mesa, CA 92624
949.660.1994
422

THIS PAGE INTENTIONALLY LEFT BLANK
423
Appendix A: Air Quality, Greenhouse Gas Emissions, and
Energy Supporting Information
CalEEMod Outputs and Calculations 1
Construction and Operation Energy Calculations 44
424
15 Argonaut Custom Report, 5/12/2026
1 / 39
15 Argonaut Custom Report
Table of Contents

1. Basic Project Information

1.1. Basic Project Information

1.2. Land Use Types

2. Emissions Summary

2.2. Construction Emissions by Year

2.2.1. Total Construction Emissions by Year, Unmitigated

2.2.2. Onsite Construction Emissions by Year, Unmitigated

2.2.3. Offsite Construction Emissions by Year, Unmitigated

2.4. Operations Emissions by Sector, Unmitigated

3. Construction Emissions Details

3.1. Demolition (2027)

3.1.1. Onsite - Unmitigated

3.1.2. Offsite - Unmitigated

3.2. Site Preparation (2027)

3.2.1. Onsite - Unmitigated
Appendix A 1
425
15 Argonaut Custom Report, 5/12/2026
2 / 39

3.2.2. Offsite - Unmitigated

3.3. Grading (2027)

3.3.1. Onsite - Unmitigated

3.3.2. Offsite - Unmitigated

3.4. Building Construction (2027)

3.4.1. Onsite - Unmitigated

3.4.2. Offsite - Unmitigated

3.5. Building Construction (2028)

3.5.1. Onsite - Unmitigated

3.5.2. Offsite - Unmitigated

3.6. Paving (2028)

3.6.1. Onsite - Unmitigated

3.6.2. Offsite - Unmitigated

3.7. Architectural Coating (2028)

3.7.1. Onsite - Unmitigated

3.7.2. Offsite - Unmitigated

4. Operations Emissions Details

4.1. Mobile Emissions by Land Use
Appendix A2
426
15 Argonaut Custom Report, 5/12/2026
3 / 39

4.1.1. Unmitigated

4.2. Energy

4.2.1. Electricity Emissions By Land Use - Unmitigated

4.2.3. Natural Gas Emissions By Land Use - Unmitigated

4.3. Area Emissions by Source

4.3.1. Unmitigated

4.4. Water Emissions by Land Use

4.4.1. Unmitigated

4.5. Waste Emissions by Land Use

4.5.1. Unmitigated

4.6. Refrigerant Emissions by Land Use

4.6.1. Unmitigated

5. Activity Data

5.1. Construction Schedule

5.2. Off-Road Equipment

5.2.1. Unmitigated

5.3. Construction Vehicles

5.3.1. Unmitigated
Appendix A 3
427
15 Argonaut Custom Report, 5/12/2026
4 / 39

5.4. Vehicles

5.4.1. Construction Vehicle Control Strategies

5.5. Architectural Coatings

5.6. Dust Mitigation

5.6.1. Construction Earthmoving Activities

5.6.2. Construction Earthmoving Control Strategies

5.7. Construction Paving

5.8. Construction Electricity Consumption and Emissions Factors

5.9. Operational Mobile Sources

5.9.1. Unmitigated

5.10. Operational Area Sources

5.10.1. Hearths

5.10.2. Architectural Coatings

5.10.3. Landscape Equipment

5.11. Operational Energy Consumption

5.11.1. Unmitigated

5.12. Operational Water and Wastewater Consumption

5.12.1. Unmitigated
Appendix A 4
428
15 Argonaut Custom Report, 5/12/2026
5 / 39

5.13. Operational Waste Generation

5.13.1. Unmitigated

5.14. Operational Refrigeration and Air Conditioning Equipment

5.14.1. Unmitigated

8. User Changes to Default Data

8.1. Justifications

8.3. Land Use

8.4. Construction

8.4.1. Construction Phases

8.4.6. Trips and VMT

8.4.9. Paving

8.5. Operations

8.5.1. Mobile Sources

8.5.1.1. Vehicle Data

8.5.2. Area Sources

8.5.2.1. Hearths

8.5.3. Energy Usage
Appendix A 5
429
15 Argonaut Custom Report, 5/12/2026
6 / 39

1. Basic Project Information

1.1. Basic Project Information
Data Field Value
Project Name 15 Argonaut
Construction Start Date 3/30/2027
Operational Year 2028
Lead Agency City of Aliso Viejo
Land Use Scale Project/site
Analysis Level for Defaults County
Windspeed (m/s) 2.50000
Precipitation (days) 6.00000
Location 15 Argonaut, Aliso Viejo, CA 92656, USA
County Orange
City Aliso Viejo
Air District South Coast AQMD
Air Basin South Coast
TAZ 6039
EDFZ 7
Electric Utility Southern California Edison
Gas Utility Southern California Gas
App Version 2022.1.1.43

1.2. Land Use Types
Land Use Subtype Size Unit Lot Acreage Building Area (sq ft) Landscape Area (sq ft)
Special Landscape
Area (sq ft)
Population Description
Condo/Townhouse 58.0000 Dwelling Unit 4.40000 94,061.0 14,092.0 0.00000 173.000 — Appendix A 6
430
15 Argonaut Custom Report, 5/12/2026
7 / 39

2. Emissions Summary

2.2. Construction Emissions by Year

2.2.1. Total Construction Emissions by Year, Unmitigated Includes both onsite and offsite emissions.

Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Year TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily -
Summer
(Max)
— — — — — — — — — — — — — — — — — —
2027 3.70557 3.10494 28.2124 29.2367 0.04989 1.17353 5.37649 6.55002 1.07979 2.69061 3.77040 — 5,662.03 5,662.03 0.24939 0.26186 3.28696 5,690.76 2028 1.33384 1.11083 9.21474 14.9748 0.02479 0.30163 0.59889 0.90052 0.27761 0.14260 0.42021 — 3,108.99 3,108.99 0.11221 0.04827 1.92565 3,128.11 Daily -
Winter
(Max)
— — — — — — — — — — — — — — — — — —
2027 2.81816 2.27711 21.6698 20.0140 0.04222 0.81439 1.72988 2.54427 0.75072 0.32708 1.07780 — 5,016.18 5,016.18 0.24972 0.26186 0.08523 5,100.54 2028 21.9616 21.9351 9.24166 14.7020 0.02479 0.30163 0.59889 0.90052 0.27761 0.14260 0.42021 — 3,083.78 3,083.78 0.11326 0.06530 0.04988 3,106.12 Average
Daily
— — — — — — — — — — — — — — — — — —
2027 0.97860 0.80889 7.16481 9.18452 0.01606 0.26597 0.68858 0.95455 0.24489 0.24077 0.48566 — 1,956.29 1,956.29 0.07927 0.05431 0.50913 1,974.96 2028 2.30878 2.19337 4.78242 7.65509 0.01262 0.15615 0.30592 0.46207 0.14372 0.07284 0.21656 — 1,573.98 1,573.98 0.05794 0.03366 0.42559 1,585.89 Annual — — — — — — — — — — — — — — — — — —
2027 0.17859 0.14762 1.30758 1.67617 0.00293 0.04854 0.12567 0.17421 0.04469 0.04394 0.08863 — 323.886 323.886 0.01312 0.00899 0.08429 326.978 2028 0.42135 0.40029 0.87279 1.39705 0.00230 0.02850 0.05583 0.08433 0.02623 0.01329 0.03952 — 260.591 260.591 0.00959 0.00557 0.07046 262.562

2.2.2. Onsite Construction Emissions by Year, Unmitigated Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Year TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Appendix A 7
431
15 Argonaut Custom Report, 5/12/2026
8 / 39
Daily - — — — — — — — — — — — — — — — — — —
Summer
(Max)
2027 3.63178 3.05170 27.9724 28.2794 0.04891 1.17173 5.11082 6.28256 1.07799 2.62664 3.70463 — 5,297.82 5,297.82 0.21490 0.04298 0.00000 5,316.00 2028 1.18481 0.99143 8.92495 12.9352 0.02340 0.30024 0.00000 0.30024 0.27622 0.00000 0.27622 — 2,397.46 2,397.46 0.09725 0.01945 0.00000 2,405.68 Daily -
Winter
(Max)
— — — — — — — — — — — — — — — — — —
2027 2.63907 2.21478 19.9005 18.6307 0.03253 0.79594 1.15513 1.95107 0.73226 0.17492 0.90718 — 3,426.90 3,426.90 0.13901 0.02780 0.00000 3,438.66 2028 21.9348 21.9122 8.92495 12.9352 0.02340 0.30024 0.00000 0.30024 0.27622 0.00000 0.27622 — 2,397.46 2,397.46 0.09725 0.01945 0.00000 2,405.68 Average
Daily
— — — — — — — — — — — — — — — — — —
2027 0.89981 0.75433 6.84587 8.27414 0.01452 0.26351 0.39556 0.65907 0.24243 0.16945 0.41188 — 1,516.17 1,516.17 0.06150 0.01230 0.00000 1,521.37 2028 2.23200 2.13206 4.61585 6.70892 0.01190 0.15537 0.00000 0.15537 0.14294 0.00000 0.14294 — 1,217.99 1,217.99 0.04941 0.00988 0.00000 1,222.17 Annual — — — — — — — — — — — — — — — — — —
2027 0.16422 0.13766 1.24937 1.51003 0.00265 0.04809 0.07219 0.12028 0.04424 0.03092 0.07517 — 251.019 251.019 0.01018 0.00204 0.00000 251.881 2028 0.40734 0.38910 0.84239 1.22438 0.00217 0.02836 0.00000 0.02836 0.02609 0.00000 0.02609 — 201.653 201.653 0.00818 0.00164 0.00000 202.345

2.2.3. Offsite Construction Emissions by Year, Unmitigated Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Year TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily -
Summer
(Max)
— — — — — — — — — — — — — — — — — —
2027 0.18094 0.12322 1.69957 2.15953 0.00969 0.01845 0.59889 0.60029 0.01845 0.15216 0.17061 — 1,598.03 1,598.03 0.11038 0.23406 3.28696 1,673.83 2028 0.14903 0.11940 0.28979 2.03954 0.00139 0.00180 0.59889 0.60029 0.00180 0.14260 0.14400 — 711.537 711.537 0.01496 0.02882 1.92565 722.424 Daily -
Winter
(Max)
— — — — — — — — — — — — — — — — — —
2027 0.17909 0.12216 1.76929 1.87263 0.00969 0.01845 0.59889 0.60029 0.01845 0.15216 0.17061 — 1,589.29 1,589.29 0.11071 0.23406 0.08523 1,661.89 2028 0.14784 0.11848 0.31670 1.76678 0.00139 0.00139 0.59889 0.60029 0.00139 0.14260 0.14400 — 686.318 686.318 0.01601 0.04585 0.04988 700.431 Appendix A 8
432
15 Argonaut Custom Report, 5/12/2026
9 / 39
Average
Daily
— — — — — — — — — — — — — — — — — —
2027 0.07879 0.05457 0.31894 0.91038 0.00153 0.00246 0.29303 0.29548 0.00246 0.07132 0.07378 — 440.119 440.119 0.01777 0.04201 0.50913 453.592 2028 0.07677 0.06131 0.16657 0.94617 0.00072 0.00077 0.30592 0.30670 0.00077 0.07284 0.07362 — 355.990 355.990 0.00853 0.02378 0.42559 363.716 Annual — — — — — — — — — — — — — — — — — —
2027 0.01438 0.00996 0.05821 0.16614 0.00028 0.00045 0.05348 0.05393 0.00045 0.01302 0.01346 — 72.8667 72.8667 0.00294 0.00696 0.08429 75.0974 2028 0.01401 0.01119 0.03040 0.17268 0.00013 0.00014 0.05583 0.05597 0.00014 0.01329 0.01344 — 58.9382 58.9382 0.00141 0.00394 0.07046 60.2173

2.4. Operations Emissions by Sector, Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Sector TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Mobile 1.12836 1.03108 0.70676 8.44245 0.02265 0.01286 2.22547 2.23833 0.01198 0.56487 0.57686 — 2,312.81 2,312.81 0.09974 0.08759 6.50925 2,347.92 Area 2.47707 2.46099 0.03116 3.29632 0.00014 0.00154 — 0.00154 0.00116 — 0.00116 0.00000 8.79786 8.79786 0.00037 0.00007 — 8.82881 Energy 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 400.497 400.497 0.03818 0.00463 — 402.830 Water — — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Waste — — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Refrig. — — — — — — — — — — — — — — — — 0.67367 0.67367 Total 3.60543 3.49208 0.73792 11.7388 0.02279 0.01440 2.22547 2.23987 0.01315 0.56487 0.57802 27.3067 2,737.28 2,764.59 2.87975 0.10262 7.18292 2,874.35 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Mobile 1.12145 1.02290 0.76763 7.86759 0.02177 0.01287 2.22547 2.23834 0.01199 0.56487 0.57686 — 2,224.42 2,224.42 0.10379 0.09156 0.16878 2,254.47 Area 2.17420 2.17420 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 Energy 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 400.497 400.497 0.03818 0.00463 — 402.830 Water — — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Waste — — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Refrig. — Appendix — A — — — — — — — — — — — — — — 0.67367 9 0.67367
433
15 Argonaut Custom Report, 5/12/2026
10 / 39
Total 3.29566 3.19711 0.76763 7.86759 0.02177 0.01287 2.22547 2.23834 0.01199 0.56487 0.57686 27.3067 2,640.10 2,667.40 2.88343 0.10653 0.84244 2,772.07 Average
Daily
— — — — — — — — — — — — — — — — — —
Mobile 1.11376 1.01537 0.77483 8.05123 0.02201 0.01286 2.21691 2.22977 0.01199 0.56273 0.57472 — 2,248.26 2,248.26 0.10311 0.09182 2.81064 2,281.01 Area 2.38164 2.37063 0.02134 2.25775 0.00010 0.00106 — 0.00106 0.00080 — 0.00080 0.00000 6.02593 6.02593 0.00025 0.00005 — 6.04713 Energy 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 400.497 400.497 0.03818 0.00463 — 402.830 Water — — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Waste — — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Refrig. — — — — — — — — — — — — — — — — 0.67367 0.67367 Total 3.49540 3.38600 0.79617 10.3090 0.02211 0.01392 2.21691 2.23083 0.01278 0.56273 0.57551 27.3067 2,669.96 2,697.27 2.88300 0.10683 3.48431 2,804.66 Annual — — — — — — — — — — — — — — — — — —
Mobile 0.20326 0.18530 0.14141 1.46935 0.00402 0.00235 0.40459 0.40693 0.00219 0.10270 0.10489 — 372.225 372.225 0.01707 0.01520 0.46533 377.648 Area 0.43465 0.43264 0.00390 0.41204 0.00002 0.00019 — 0.00019 0.00015 — 0.00015 0.00000 0.99766 0.99766 0.00004 0.00001 — 1.00117 Energy 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 66.3068 66.3068 0.00632 0.00077 — 66.6931 Water — — — — — — — — — — — 0.69050 2.51262 3.20312 0.07104 0.00171 — 5.48914 Waste — — — — — — — — — — — 3.83043 0.00000 3.83043 0.38284 0.00000 — 13.4014 Refrig. — — — — — — — — — — — — — — — — 0.11153 0.11153 Total 0.63791 0.61795 0.14530 1.88139 0.00403 0.00254 0.40459 0.40713 0.00233 0.10270 0.10503 4.52093 442.043 446.563 0.47731 0.01769 0.57687 464.344

3. Construction Emissions Details

3.1. Demolition (2027)

3.1.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Appendix A 10
434
15 Argonaut Custom Report, 5/12/2026
11 / 39
Off-Roa
Equipment

2.63907 2.21478 19.9005 18.6307 0.03253 0.79594 — 0.79594 0.73226 — 0.73226 — 3,426.90 3,426.90 0.13901 0.02780 — 3,438.66 Demoliti
on
— — — — — — 1.15513 1.15513 — 0.17492 0.17492 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

2.63907 2.21478 19.9005 18.6307 0.03253 0.79594 — 0.79594 0.73226 — 0.73226 — 3,426.90 3,426.90 0.13901 0.02780 — 3,438.66 Demoliti
on
— — — — — — 1.15513 1.15513 — 0.17492 0.17492 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.18799 0.15777 1.41757 1.32712 0.00232 0.05670 — 0.05670 0.05216 — 0.05216 — 244.108 244.108 0.00990 0.00198 — 244.945 Demoliti
on
— — — — — — 0.08228 0.08228 — 0.01246 0.01246 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.03431 0.02879 0.25871 0.24220 0.00042 0.01035 — 0.01035 0.00952 — 0.00952 — 40.4148 40.4148 0.00164 0.00033 — 40.5535 Demoliti
on
— — — — — — 0.01502 0.01502 — 0.00227 0.00227 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Appendix A 11
435
15 Argonaut Custom Report, 5/12/2026
12 / 39

3.1.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.04993 0.04282 0.04497 0.74175 0.00000 0.00000 0.19606 0.19606 0.00000 0.04596 0.04596 — 192.036 192.036 0.00198 0.00711 0.60890 194.813 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.13100 0.02168 1.65459 0.73896 0.00969 0.01845 0.37869 0.39714 0.01845 0.10620 0.12465 — 1,405.99 1,405.99 0.10840 0.22695 2.67807 1,479.01 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.04993 0.04249 0.04597 0.63791 0.00000 0.00000 0.19606 0.19606 0.00000 0.04596 0.04596 — 182.764 182.764 0.00231 0.00711 0.01583 184.957 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.12916 0.01983 1.72332 0.74542 0.00969 0.01845 0.37869 0.39714 0.01845 0.10620 0.12465 — 1,406.52 1,406.52 0.10840 0.22695 0.06939 1,476.93 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.00353 0.00303 0.00369 0.04738 0.00000 0.00000 0.01391 0.01391 0.00000 0.00326 0.00326 — 13.1966 13.1966 0.00016 0.00051 0.01876 13.3704 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00930 0.00148 0.12351 0.05284 0.00069 0.00131 0.02689 0.02821 0.00131 0.00754 0.00886 — 100.169 100.169 0.00772 0.01617 0.08232 105.262 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00064 0.00055 0.00067 0.00865 0.00000 0.00000 0.00254 0.00254 0.00000 0.00059 0.00059 — 2.18485 2.18485 0.00003 0.00008 0.00311 2.21363 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00170 0.00027 0.02254 0.00964 0.00013 0.00024 0.00491 0.00515 0.00024 0.00138 0.00162 — 16.5841 16.5841 0.00128 0.00268 0.01363 17.4273

3.2. Site Preparation (2027)

3.2.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG
Appendix
ROG
A
NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R 12 CO2e 436
15 Argonaut Custom Report, 5/12/2026
13 / 39
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

3.63178 3.05170 27.9724 28.2794 0.04891 1.17173 — 1.17173 1.07799 — 1.07799 — 5,297.82 5,297.82 0.21490 0.04298 — 5,316.00 Dust
From
Material
Movement
— — — — — — 5.11082 5.11082 — 2.62664 2.62664 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.12935 0.10869 0.99628 1.00721 0.00174 0.04173 — 0.04173 0.03839 — 0.03839 — 188.689 188.689 0.00765 0.00153 — 189.337 Dust
From
Material
Movement
— — — — — — 0.18203 0.18203 — 0.09355 0.09355 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.02361 0.01984 0.18182 0.18382 0.00032 0.00762 — 0.00762 0.00701 — 0.00701 — 31.2397 31.2397 0.00127 0.00025 — 31.3469 Dust
From
Material
Movement
— — — — — — 0.03322 0.03322 — 0.01707 0.01707 — — — — — — — Appendix A 13
437
15 Argonaut Custom Report, 5/12/2026
14 / 39
Onsite 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 truck

3.2.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.05826 0.04996 0.05247 0.86537 0.00000 0.00000 0.22874 0.22874 0.00000 0.05362 0.05362 — 224.042 224.042 0.00231 0.00829 0.71038 227.282 Vendor 0.01554 0.00328 0.18755 0.09201 0.00099 0.00180 0.03692 0.03872 0.00180 0.01035 0.01215 — 140.167 140.167 0.01208 0.02265 0.26111 147.479 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.00206 0.00177 0.00215 0.02764 0.00000 0.00000 0.00812 0.00812 0.00000 0.00190 0.00190 — 7.69803 7.69803 0.00010 0.00030 0.01094 7.79942 Vendor 0.00055 0.00011 0.00697 0.00330 0.00004 0.00006 0.00131 0.00138 0.00006 0.00037 0.00043 — 4.99377 4.99377 0.00043 0.00081 0.00401 5.24889 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00038 0.00032 0.00039 0.00504 0.00000 0.00000 0.00148 0.00148 0.00000 0.00035 0.00035 — 1.27450 1.27450 0.00002 0.00005 0.00181 1.29128 Vendor 0.00010 0.00002 0.00127 0.00060 0.00001 0.00001 0.00024 0.00025 0.00001 0.00007 0.00008 — 0.82678 0.82678 0.00007 0.00013 0.00066 0.86901 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.3. Grading (2027)

3.3.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Appendix A 14
438
15 Argonaut Custom Report, 5/12/2026
15 / 39
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

1.88795 1.58640 14.2321 17.2743 0.02733 0.59767 — 0.59767 0.54986 — 0.54986 — 2,960.07 2,960.07 0.12007 0.02401 — 2,970.23 Dust
From
Material
Movement
— — — — — — 1.84247 1.84247 — 0.89058 0.89058 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.13448 0.11300 1.01379 1.23050 0.00195 0.04257 — 0.04257 0.03917 — 0.03917 — 210.854 210.854 0.00855 0.00171 — 211.578 Dust
From
Material
Movement
— — — — — — 0.13124 0.13124 — 0.06344 0.06344 — — — — — — — Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.02454 0.02062 0.18502 0.22457 0.00036 0.00777 — 0.00777 0.00715 — 0.00715 — 34.9094 34.9094 0.00142 0.00028 — 35.0292 Dust
From
Material
Movement
— — — — — — 0.02395 0.02395 — 0.01158 0.01158 — — — — — — — Appendix A 15
439
15 Argonaut Custom Report, 5/12/2026
16 / 39
Onsite 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 truck

3.3.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.04993 0.04282 0.04497 0.74175 0.00000 0.00000 0.19606 0.19606 0.00000 0.04596 0.04596 — 192.036 192.036 0.00198 0.00711 0.60890 194.813 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.05707 0.00945 0.72084 0.32194 0.00422 0.00804 0.16498 0.17302 0.00804 0.04627 0.05431 — 612.538 612.538 0.04723 0.09887 1.16673 644.350 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.00353 0.00303 0.00369 0.04738 0.00000 0.00000 0.01391 0.01391 0.00000 0.00326 0.00326 — 13.1966 13.1966 0.00016 0.00051 0.01876 13.3704 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00405 0.00064 0.05381 0.02302 0.00030 0.00057 0.01172 0.01229 0.00057 0.00329 0.00386 — 43.6397 43.6397 0.00336 0.00704 0.03586 45.8585 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00064 0.00055 0.00067 0.00865 0.00000 0.00000 0.00254 0.00254 0.00000 0.00059 0.00059 — 2.18485 2.18485 0.00003 0.00008 0.00311 2.21363 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00074 0.00012 0.00982 0.00420 0.00005 0.00010 0.00214 0.00224 0.00010 0.00060 0.00070 — 7.22506 7.22506 0.00056 0.00117 0.00594 7.59240

3.4. Building Construction (2027)

3.4.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Appendix A 16
440
15 Argonaut Custom Report, 5/12/2026
17 / 39
Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

1.23076 1.02988 9.39093 12.9379 0.02340 0.33657 — 0.33657 0.30965 — 0.30965 — 2,397.08 2,397.08 0.09724 0.01945 — 2,405.30 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

1.23076 1.02988 9.39093 12.9379 0.02340 0.33657 — 0.33657 0.30965 — 0.30965 — 2,397.08 2,397.08 0.09724 0.01945 — 2,405.30 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.44799 0.37487 3.41823 4.70931 0.00852 0.12251 — 0.12251 0.11271 — 0.11271 — 872.518 872.518 0.03539 0.00708 — 875.512 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.08176 0.06841 0.62383 0.85945 0.00155 0.02236 — 0.02236 0.02057 — 0.02057 — 144.455 144.455 0.00586 0.00117 — 144.951 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.4.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Appendix A 17
441
15 Argonaut Custom Report, 5/12/2026
18 / 39
Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.13902 0.11922 0.12521 2.06502 0.00000 0.00000 0.54584 0.54584 0.00000 0.12794 0.12794 — 534.627 534.627 0.00552 0.01979 1.69516 542.359 Vendor 0.01509 0.00399 0.19033 0.09451 0.00139 0.00139 0.05305 0.05444 0.00139 0.01466 0.01605 — 190.871 190.871 0.00971 0.02605 0.45657 199.334 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.13902 0.11830 0.12797 1.77593 0.00000 0.00000 0.54584 0.54584 0.00000 0.12794 0.12794 — 508.816 508.816 0.00644 0.01979 0.04408 514.920 Vendor 0.01495 0.00385 0.19837 0.09670 0.00139 0.00139 0.05305 0.05444 0.00139 0.01466 0.01605 — 190.972 190.972 0.00957 0.02605 0.01182 198.987 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.05027 0.04306 0.05244 0.67407 0.00000 0.00000 0.19792 0.19792 0.00000 0.04638 0.04638 — 187.734 187.734 0.00235 0.00720 0.26685 190.207 Vendor 0.00549 0.00145 0.07267 0.03475 0.00051 0.00051 0.01925 0.01975 0.00051 0.00532 0.00583 — 69.4911 69.4911 0.00348 0.00948 0.07163 72.4758 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00917 0.00786 0.00957 0.12302 0.00000 0.00000 0.03612 0.03612 0.00000 0.00846 0.00846 — 31.0816 31.0816 0.00039 0.00119 0.04418 31.4909 Vendor 0.00100 0.00027 0.01326 0.00634 0.00009 0.00009 0.00351 0.00361 0.00009 0.00097 0.00106 — 11.5050 11.5050 0.00058 0.00157 0.01186 11.9992 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.5. Building Construction (2028)

3.5.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Appendix A 18
442
15 Argonaut Custom Report, 5/12/2026
19 / 39
Off-Roa
Equipment

1.18481 0.99143 8.92495 12.9352 0.02340 0.30024 — 0.30024 0.27622 — 0.27622 — 2,397.46 2,397.46 0.09725 0.01945 — 2,405.68 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

1.18481 0.99143 8.92495 12.9352 0.02340 0.30024 — 0.30024 0.27622 — 0.27622 — 2,397.46 2,397.46 0.09725 0.01945 — 2,405.68 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.54951 0.45982 4.13936 5.99932 0.01085 0.13925 — 0.13925 0.12811 — 0.12811 — 1,111.93 1,111.93 0.04510 0.00902 — 1,115.75 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.10029 0.08392 0.75543 1.09488 0.00198 0.02541 — 0.02541 0.02338 — 0.02338 — 184.093 184.093 0.00747 0.00149 — 184.725 Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.5.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Appendix A 19
443
15 Argonaut Custom Report, 5/12/2026
20 / 39
Worker 0.13534 0.11554 0.10726 1.94810 0.00000 0.00000 0.54584 0.54584 0.00000 0.12794 0.12794 — 525.091 525.091 0.00552 0.00276 1.51493 527.567 Vendor 0.01370 0.00385 0.18254 0.09145 0.00139 0.00139 0.05305 0.05444 0.00139 0.01466 0.01605 — 186.446 186.446 0.00943 0.02605 0.41072 194.856 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.13441 0.11462 0.12613 1.67328 0.00000 0.00000 0.54584 0.54584 0.00000 0.12794 0.12794 — 499.768 499.768 0.00644 0.01979 0.03921 505.867 Vendor 0.01342 0.00385 0.19057 0.09350 0.00139 0.00139 0.05305 0.05444 0.00139 0.01466 0.01605 — 186.550 186.550 0.00957 0.02605 0.01067 194.564 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.06277 0.05359 0.05850 0.81129 0.00000 0.00000 0.25218 0.25218 0.00000 0.05910 0.05910 — 234.959 234.959 0.00299 0.00918 0.30387 238.073 Vendor 0.00629 0.00185 0.08840 0.04286 0.00065 0.00065 0.02452 0.02517 0.00065 0.00678 0.00742 — 86.4935 86.4935 0.00444 0.01208 0.08230 90.2876 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Worker 0.01146 0.00978 0.01068 0.14806 0.00000 0.00000 0.04602 0.04602 0.00000 0.01079 0.01079 — 38.9001 38.9001 0.00049 0.00152 0.05031 39.4157 Vendor 0.00115 0.00034 0.01613 0.00782 0.00012 0.00012 0.00448 0.00459 0.00012 0.00124 0.00135 — 14.3200 14.3200 0.00073 0.00200 0.01363 14.9481 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.6. Paving (2028)

3.6.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.74648 0.62588 5.84990 8.80025 0.01296 0.21041 — 0.21041 0.19358 — 0.19358 — 1,350.28 1,350.28 0.05477 0.01095 — 1,354.92 Appendix A 20
444
15 Argonaut Custom Report, 5/12/2026
21 / 39
Paving 0.09472 0.09472 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.05317 0.04458 0.41671 0.62687 0.00092 0.01499 — 0.01499 0.01379 — 0.01379 — 96.1844 96.1844 0.00390 0.00078 — 96.5145 Paving 0.00675 0.00675 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.00970 0.00814 0.07605 0.11440 0.00017 0.00274 — 0.00274 0.00252 — 0.00252 — 15.9244 15.9244 0.00065 0.00013 — 15.9791 Paving 0.00123 0.00123 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.6.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.06482 0.05534 0.05137 0.93300 0.00000 0.00000 0.26142 0.26142 0.00000 0.06128 0.06128 — 251.480 251.480 0.00265 0.00132 0.72554 252.666 Vendor 0.01545 0.00328 0.18136 0.09030 0.00099 0.00180 0.03692 0.03872 0.00180 0.01035 0.01215 — 136.974 136.974 0.01109 0.02175 0.24053 143.972 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Appendix A 21
445
15 Argonaut Custom Report, 5/12/2026
22 / 39
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.00462 0.00394 0.00430 0.05968 0.00000 0.00000 0.01855 0.01855 0.00000 0.00435 0.00435 — 17.2828 17.2828 0.00022 0.00068 0.02235 17.5119 Vendor 0.00109 0.00022 0.01351 0.00647 0.00007 0.00013 0.00262 0.00275 0.00013 0.00074 0.00086 — 9.76017 9.76017 0.00079 0.00155 0.00738 10.2489 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00084 0.00072 0.00079 0.01089 0.00000 0.00000 0.00339 0.00339 0.00000 0.00079 0.00079 — 2.86137 2.86137 0.00004 0.00011 0.00370 2.89929 Vendor 0.00020 0.00004 0.00246 0.00118 0.00001 0.00002 0.00048 0.00050 0.00002 0.00013 0.00016 — 1.61591 1.61591 0.00013 0.00026 0.00122 1.69683 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.7. Architectural Coating (2028)

3.7.1. Onsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.12985 0.10731 0.80814 1.11833 0.00173 0.01536 — 0.01536 0.01413 — 0.01413 — 133.517 133.517 0.00542 0.00108 — 133.975 Architect
ural
Coating
s

21.8049 21.8049 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Appendix A 22
446
15 Argonaut Custom Report, 5/12/2026
23 / 39
Average
Daily
— — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.00961 0.00794 0.05978 0.08273 0.00013 0.00114 — 0.00114 0.00105 — 0.00105 — 9.87660 9.87660 0.00040 0.00008 — 9.91050 Architect
ural
Coating
s

1.61297 1.61297 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Off-Roa
d
Equipm
ent

0.00175 0.00145 0.01091 0.01510 0.00002 0.00021 — 0.00021 0.00019 — 0.00019 — 1.63518 1.63518 0.00007 0.00001 — 1.64080 Architect
ural
Coating
s

0.29437 0.29437 — — — — — — — — — — — — — — — —
Onsite
truck

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

3.7.2. Offsite - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Location TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Worker 0.02688 0.02292 0.02523 0.33466 0.00000 0.00000 0.10917 0.10917 0.00000 0.02559 0.02559 — 99.9535 99.9535 0.00129 0.00396 0.00784 101.173 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Appendix A 23
447
15 Argonaut Custom Report, 5/12/2026
24 / 39
Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Average
Daily
— — — — — — — — — — — — — — — — — —
Worker 0.00200 0.00171 0.00187 0.02588 0.00000 0.00000 0.00804 0.00804 0.00000 0.00189 0.00189 — 7.49489 7.49489 0.00010 0.00029 0.00969 7.59423 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Annual — — — — — — — — — — — — — — — — — —
Worker 0.00037 0.00031 0.00034 0.00472 0.00000 0.00000 0.00147 0.00147 0.00000 0.00034 0.00034 — 1.24086 1.24086 0.00002 0.00005 0.00160 1.25731 Vendor 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 Hauling 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000

4. Operations Emissions Details

4.1. Mobile Emissions by Land Use

4.1.1. Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

1.12836 1.03108 0.70676 8.44245 0.02265 0.01286 2.22547 2.23833 0.01198 0.56487 0.57686 — 2,312.81 2,312.81 0.09974 0.08759 6.50925 2,347.92 Total 1.12836 1.03108 0.70676 8.44245 0.02265 0.01286 2.22547 2.23833 0.01198 0.56487 0.57686 — 2,312.81 2,312.81 0.09974 0.08759 6.50925 2,347.92 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

1.12145 1.02290 0.76763 7.86759 0.02177 0.01287 2.22547 2.23834 0.01199 0.56487 0.57686 — 2,224.42 2,224.42 0.10379 0.09156 0.16878 2,254.47 Appendix A 24
448
15 Argonaut Custom Report, 5/12/2026
25 / 39
Total 1.12145 1.02290 0.76763 7.86759 0.02177 0.01287 2.22547 2.23834 0.01199 0.56487 0.57686 — 2,224.42 2,224.42 0.10379 0.09156 0.16878 2,254.47 Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

0.20326 0.18530 0.14141 1.46935 0.00402 0.00235 0.40459 0.40693 0.00219 0.10270 0.10489 — 372.225 372.225 0.01707 0.01520 0.46533 377.648 Total 0.20326 0.18530 0.14141 1.46935 0.00402 0.00235 0.40459 0.40693 0.00219 0.10270 0.10489 — 372.225 372.225 0.01707 0.01520 0.46533 377.648

4.2. Energy

4.2.1. Electricity Emissions By Land Use - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — — 400.497 400.497 0.03818 0.00463 — 402.830 Total — — — — — — — — — — — — 400.497 400.497 0.03818 0.00463 — 402.830 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — — 400.497 400.497 0.03818 0.00463 — 402.830 Total — — — — — — — — — — — — 400.497 400.497 0.03818 0.00463 — 402.830 Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — — 66.3068 66.3068 0.00632 0.00077 — 66.6931 Total — — — — — — — — — — — — 66.3068 66.3068 0.00632 0.00077 — 66.6931 Appendix A 25
449
15 Argonaut Custom Report, 5/12/2026
26 / 39

4.2.3. Natural Gas Emissions By Land Use - Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000 Total 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000 Total 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000 Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se

0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000 Total 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 — 0.00000 0.00000 0.00000 0.00000 — 0.00000

4.3. Area Emissions by Source

4.3.1. Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Source TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Hearths 0.00000
Appendix

0.00000
A

0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 —260.00000 450 15 Argonaut Custom Report, 5/12/2026
27 / 39
Consum
Products

2.01291 2.01291 — — — — — — — — — — — — — — — —
Architect
ural
Coating
s

0.16130 0.16130 — — — — — — — — — — — — — — — —
Landsca
pe
Equipm
ent

0.30286 0.28679 0.03116 3.29632 0.00014 0.00154 — 0.00154 0.00116 — 0.00116 — 8.79786 8.79786 0.00037 0.00007 — 8.82881 Total 2.47707 2.46099 0.03116 3.29632 0.00014 0.00154 — 0.00154 0.00116 — 0.00116 0.00000 8.79786 8.79786 0.00037 0.00007 — 8.82881 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Hearths 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 Consum
er
Product
s

2.01291 2.01291 — — — — — — — — — — — — — — — —
Architect
ural
Coating
s

0.16130 0.16130 — — — — — — — — — — — — — — — —
Total 2.17420 2.17420 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 Annual — — — — — — — — — — — — — — — — — —
Hearths 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 0.00000 — 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 — 0.00000 Consum
er
Product
s

0.36736 0.36736 — — — — — — — — — — — — — — — —
Architect
ural
Coating
s

0.02944 0.02944 — — — — — — — — — — — — — — — —
Appendix A 27
451
15 Argonaut Custom Report, 5/12/2026
28 / 39
Landsca 0.03786 0.03585 0.00390 0.41204 0.00002 0.00019 — 0.00019 0.00015 — 0.00015 — 0.99766 0.99766 0.00004 0.00001 — 1.00117 pe
Equipm
ent
Total 0.43465 0.43264 0.00390 0.41204 0.00002 0.00019 — 0.00019 0.00015 — 0.00015 0.00000 0.99766 0.99766 0.00004 0.00001 — 1.00117

4.4. Water Emissions by Land Use

4.4.1. Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Total — — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Total — — — — — — — — — — — 4.17066 15.1763 19.3470 0.42910 0.01034 — 33.1547 Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 0.69050 2.51262 3.20312 0.07104 0.00171 — 5.48914 Total — — — — — — — — — — — 0.69050 2.51262 3.20312 0.07104 0.00171 — 5.48914

4.5. Waste Emissions by Land Use
Appendix A 28
452
15 Argonaut Custom Report, 5/12/2026
29 / 39

4.5.1. Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Total — — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Total — — — — — — — — — — — 23.1360 0.00000 23.1360 2.31236 0.00000 — 80.9451 Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — 3.83043 0.00000 3.83043 0.38284 0.00000 — 13.4014 Total — — — — — — — — — — — 3.83043 0.00000 3.83043 0.38284 0.00000 — 13.4014

4.6. Refrigerant Emissions by Land Use

4.6.1. Unmitigated
Criteria Pollutants (lb/day for daily, ton/yr for annual) and GHGs (lb/day for daily, MT/yr for annual) Land
Use
TOG ROG NOx CO SO2 PM10E PM10D PM10T PM2.5E PM2.5D PM2.5T BCO2 NBCO2 CO2T CH4 N2O R CO2e Daily,
Summer
(Max)
— — — — — — — — — — — — — — — — — —
Appendix A 29
453
15 Argonaut Custom Report, 5/12/2026
30 / 39
Condo/T — — — — — — — — — — — — — — — — 0.67367 0.67367 Total — — — — — — — — — — — — — — — — 0.67367 0.67367
Daily,
Winter
(Max)
— — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — — — — — — 0.67367 0.67367
Total — — — — — — — — — — — — — — — — 0.67367 0.67367
Annual — — — — — — — — — — — — — — — — — —
Condo/T
ownhou
se
— — — — — — — — — — — — — — — — 0.11153 0.11153
Total — — — — — — — — — — — — — — — — 0.11153 0.11153

5. Activity Data

5.1. Construction Schedule
Phase Name Phase Type Start Date End Date Days Per Week Work Days per Phase Phase Description Demolition Demolition 3/30/2027 5/4/2027 5.00000 26.0000 — Site Preparation Site Preparation 5/5/2027 5/21/2027 5.00000 13.0000 — Grading Grading 5/24/2027 6/28/2027 5.00000 26.0000 —
Building Construction Building Construction 6/29/2027 8/24/2028 5.00000 303.000 — Paving Paving 8/25/2028 9/29/2028 5.00000 26.0000 —
Architectural Coating Architectural Coating 10/2/2028 11/7/2028 5.00000 27.0000 —

5.2. Off-Road Equipment

5.2.1. Unmitigated
Phase Name Equipment Type Fuel Type Engine Tier Number per Day Hours Per Day Horsepower Load Factor Appendix A 30
454
15 Argonaut Custom Report, 5/12/2026
31 / 39
Demolition Concrete/Industrial
Saws
Diesel Average 1.000000 8.00000 33.0000 0.73000
Demolition Excavators Diesel Average 3.00000 8.00000 36.0000 0.38000 Demolition Rubber Tired Dozers Diesel Average 2.00000 8.00000 367.000 0.40000 Site Preparation Rubber Tired Dozers Diesel Average 3.00000 8.00000 367.000 0.40000 Site Preparation Tractors/Loaders/Back
hoes
Diesel Average 4.00000 8.00000 84.0000 0.37000
Grading Excavators Diesel Average 1.000000 8.00000 36.0000 0.38000 Grading Graders Diesel Average 1.000000 8.00000 148.000 0.41000 Grading Rubber Tired Dozers Diesel Average 1.000000 8.00000 367.000 0.40000 Grading Tractors/Loaders/Back
hoes
Diesel Average 3.00000 8.00000 84.0000 0.37000
Building Construction Cranes Diesel Average 1.000000 7.00000 367.000 0.29000 Building Construction Forklifts Diesel Average 3.00000 8.00000 82.0000 0.20000 Building Construction Generator Sets Diesel Average 1.000000 8.00000 14.0000 0.74000 Building Construction Tractors/Loaders/Back
hoes
Diesel Average 3.00000 7.00000 84.0000 0.37000
Building Construction Welders Diesel Average 1.000000 8.00000 46.0000 0.45000 Paving Pavers Diesel Average 1.000000 8.00000 81.0000 0.42000 Paving Paving Equipment Diesel Average 2.00000 6.00000 89.0000 0.36000 Paving Rollers Diesel Average 2.00000 6.00000 36.0000 0.38000 Paving Cement and Mortar
Mixers
Diesel Average 2.00000 6.00000 10.00000 0.56000
Paving Tractors/Loaders/Back
hoes
Diesel Average 1.000000 8.00000 84.0000 0.37000
Architectural Coating Air Compressors Diesel Average 1.000000 6.00000 37.0000 0.48000

5.3. Construction Vehicles

5.3.1. Unmitigated
Appendix A 31
455
15 Argonaut Custom Report, 5/12/2026
32 / 39
Phase Name Trip Type One-Way Trips per Day Miles per Trip Vehicle Mix Demolition Worker 15.0000 18.5000 LDA,LDT1,LDT2
Demolition Vendor 0.00000 10.2000 HHDT,MHDT
Demolition Hauling 20.9231 20.0000 HHDT
Demolition Onsite truck 0.00000 0.00000 HHDT
Site Preparation Worker 17.5000 18.5000 LDA,LDT1,LDT2
Site Preparation Vendor 4.00000 10.2000 HHDT
Site Preparation Hauling 0.00000 20.0000 HHDT
Site Preparation Onsite truck 0.00000 0.00000 HHDT
Grading Worker 15.0000 18.5000 LDA,LDT1,LDT2
Grading Vendor 0.00000 10.2000 HHDT,MHDT
Grading Hauling 9.11538 20.0000 HHDT
Grading Onsite truck 0.00000 0.00000 HHDT
Building Construction Worker 41.7600 18.5000 LDA,LDT1,LDT2 Building Construction Vendor 6.20020 10.2000 HHDT,MHDT
Building Construction Hauling 0.00000 20.0000 HHDT
Building Construction Onsite truck 0.00000 0.00000 HHDT Paving Worker 20.0000 18.5000 LDA,LDT1,LDT2
Paving Vendor 4.00000 10.2000 HHDT
Paving Hauling 0.00000 20.0000 HHDT
Paving Onsite truck 0.00000 0.00000 HHDT
Architectural Coating Worker 8.35200 18.5000 LDA,LDT1,LDT2 Architectural Coating Vendor 0.00000 10.2000 HHDT,MHDT
Architectural Coating Hauling 0.00000 20.0000 HHDT
Architectural Coating Onsite truck 0.00000 0.00000 HHDT

5.4. Vehicles
Appendix A 32
456
15 Argonaut Custom Report, 5/12/2026
33 / 39

5.4.1. Construction Vehicle Control Strategies
Non-applicable. No control strategies activated by user.

5.5. Architectural Coatings
Phase Name Residential Interior Area
Coated (sq ft)
Residential Exterior Area
Coated (sq ft)
Non-Residential Interior Area
Coated (sq ft)
Non-Residential Exterior Area
Coated (sq ft)
Parking Area Coated (sq ft)
Architectural Coating 190,474 63,491.2 0.00000 0.00000 —

5.6. Dust Mitigation

5.6.1. Construction Earthmoving Activities
Phase Name Material Imported (Cubic
Yards)
Material Exported (Cubic
Yards)
Acres Graded (acres) Material Demolished (Ton of
Debris)
Acres Paved (acres)
Demolition 0.00000 0.00000 0.00000 2,173.00 0.00000
Site Preparation 0.00000 0.00000 19.5000 0.00000 0.00000 Grading 0.00000 1,890.00 26.0000 0.00000 0.00000
Paving 0.00000 0.00000 0.00000 0.00000 0.94000

5.6.2. Construction Earthmoving Control Strategies
Control Strategies Applied Frequency (per day) PM10 Reduction PM2.5 Reduction Water Exposed Area 3 74% 74%
Water Demolished Area 2 36% 36%

5.7. Construction Paving
Phase Name Land Use Area Paved (acres) % Asphalt
Paving Condo/Townhouse 0.94000 100%

5.8. Construction Electricity Consumption and Emissions Factors Appendix A 33
457
15 Argonaut Custom Report, 5/12/2026
34 / 39
kWh per Year and Emission Factor (lb/MWh)
Year kWh per Year CO2 CH4 N2O
2027 0.00000 531.983 0.03300 0.00400
2028 0.00000 531.983 0.03300 0.00400

5.9. Operational Mobile Sources

5.9.1. Unmitigated
Land Use Type Trips/Weekday Trips/Saturday Trips/Sunday Trips/Year VMT/Weekday VMT/Saturday VMT/Sunday VMT/Year Condo/Townhouse 356.000 356.000 356.000 129,940 3,145.07 3,145.07 3,145.07 1,147,950

5.10. Operational Area Sources

5.10.1. Hearths
Land Use Hearth Type Unmitigated (number) Mitigated (number) Condo/Townhouse Wood Fireplaces 0 0
Condo/Townhouse Gas Fireplaces 0 0
Condo/Townhouse Propane Fireplaces 0 0
Condo/Townhouse Electric Fireplaces 0 0
Condo/Townhouse No Fireplaces 58 58
Condo/Townhouse Conventional Wood Stoves 0 0
Condo/Townhouse Catalytic Wood Stoves 3 3
Condo/Townhouse Non-Catalytic Wood Stoves 3 3
Condo/Townhouse Pellet Wood Stoves 0 0

5.10.2. Architectural Coatings
Residential Interior Area Coated (sq
ft)
Residential Exterior Area Coated (sq
ft)
Non-Residential Interior Area Coated
(sq ft)
Non-Residential Exterior Area
Coated (sq ft)
Parking Area Coated (sq ft)
Appendix A 34
458
15 Argonaut Custom Report, 5/12/2026
35 / 39
190,474 63,491.2 0.00000 0.00000 —

5.10.3. Landscape Equipment
Season Unit Value
Snow Days day/yr 0.00000
Summer Days day/yr 250.000

5.11. Operational Energy Consumption

5.11.1. Unmitigated
Electricity (kWh/yr) and CO2 and CH4 and N2O and Natural Gas (kBTU/yr) Land Use Electricity (kWh/yr) CO2 CH4 N2O Natural Gas (kBTU/yr) Condo/Townhouse 422,250 346.196 0.0330 0.0040 0.00000

5.12. Operational Water and Wastewater Consumption

5.12.1. Unmitigated
Land Use Indoor Water (gal/year) Outdoor Water (gal/year) Condo/Townhouse 2,176,488 223,224

5.13. Operational Waste Generation

5.13.1. Unmitigated
Land Use Waste (ton/year) Cogeneration (kWh/year)
Condo/Townhouse 42.9289 0.00000

5.14. Operational Refrigeration and Air Conditioning Equipment Appendix A 35
459
15 Argonaut Custom Report, 5/12/2026
36 / 39

5.14.1. Unmitigated
Land Use Equipment Type Refrigerant GWP Quantity (kg) Operations Leak Rate Service Leak Rate Times Serviced Condo/Townhouse Average room A/C &
Other residential A/C
and heat pumps
R-410A 2,088.00 0.00225 2.50000 2.50000 10.00000
Condo/Townhouse Household
refrigerators and/or
freezers
R-134a 1,430.00 0.11538 0.60000 0.00000 1.000000

8. User Changes to Default Data

8.1. Justifications
Screen Justification
Land Use Per project description the project consists of 58 Townhomes with 94,061 SF of building space and 14,092 SF of landscaping area per the site plan.

Construction: Construction Phases Adjusted construction schedule based on the applicant's construction timeline.

Construction: Trips and VMT Conservatively added 4 additional trips for vendor trips during site prep phase. Asphalt vendor trips based on paved acreage.

Construction: Paving Paved area = site area (191,664SF) minus open space and slope (98142 SF) - bldg coverage (42,933 SF) = 50,589 SF/43,560-22.4% = 0.94.

Operations: Vehicle Data Trip rates were adjusted per project specific traffic study prepared by Urban Crossroad, Inc for 15 Argonaut.

Operations: Hearths Wood stoves is prohibited. Project will be all electric.

Operations: Energy Use Updated as per Measure E-15 using CAPCOA GHG Handbook, Table E 15.1 and 2.

Commercial Energy Consumption by End Use, Electricity Demand Forecast Zone, and Building Type.

CAPCOA, 2024. https://caleemod.com/documents/handbook/full_handbook.pdf

8.3. Land Use
Model Parameter Units Default Value New Value
Lot Area
Appendix A
acre 3.62500 4.40000
36 460
15 Argonaut Custom Report, 5/12/2026
37 / 39
Building Area sq. ft 61,480.0 94,061.0
Landscape Area sq. ft — 14,092.0
Special Landscape Area sq. ft — 0.00000

8.4. Construction

8.4.1. Construction Phases
Phase Type Phase Name Model Parameter Default Value New Value Demolition Demolition End Date 4/27/2027 5/4/2027
Demolition Demolition Work Days per Phase 20.0000 26.0000 Site Preparation Site Preparation Start Date 4/28/2027 5/5/2027 Site Preparation Site Preparation End Date 5/5/2027 5/21/2027 Site Preparation Site Preparation Work Days per Phase 5.00000 13.0000 Grading Grading Start Date 5/6/2027 5/24/2027
Grading Grading End Date 5/17/2027 6/28/2027
Grading Grading Work Days per Phase 8.00000 26.0000
Building Construction Building Construction Start Date 5/18/2027 6/29/2027 Building Construction Building Construction End Date 4/4/2028 8/24/2028 Building Construction Building Construction Work Days per Phase 230.000 303.000 Paving Paving Start Date 4/5/2028 8/25/2028
Paving Paving End Date 4/30/2028 9/29/2028
Paving Paving Work Days per Phase 18.0000 26.0000
Architectural Coating Architectural Coating Start Date 5/1/2028 10/2/2028 Architectural Coating Architectural Coating End Date 5/26/2028 11/7/2028 Architectural Coating Architectural Coating Work Days per Phase 18.0000 27.0000

8.4.6. Trips and VMT
Phase Name
Appendix A
Trip Type Model Parameter Default Value New Value
37 461
15 Argonaut Custom Report, 5/12/2026
38 / 39
Site Preparation Vendor One-Way Trips per Day — 4.00000 Site Preparation Vendor Vehicle Mix HHDT,MHDT HHDT
Paving Vendor One-Way Trips per Day — 4.00000
Paving Vendor Vehicle Mix HHDT,MHDT HHDT

8.4.9. Paving
Phase Name Land Use Model Parameter Units Default Value New Value Paving Condo/Townhouse Area Paved acres — 0.94000
Paving Condo/Townhouse % Asphalt % 0.00000 100.0000

8.5. Operations

8.5.1. Mobile Sources

8.5.1.1. Vehicle Data
Land Use Model Parameter Units Default Value New Value
Condo/Townhouse Weekday Trip Rate size/day 7.32000 6.13793 Condo/Townhouse Saturday Trip Rate size/day 8.14000 6.13793 Condo/Townhouse Sunday Trip Rate size/day 6.28000 6.13793

8.5.2. Area Sources

8.5.2.1. Hearths
Land Use Model Parameter Units Default Value New Value
Condo/Townhouse Wood Fireplaces — 3 0
Condo/Townhouse Gas Fireplaces — 49 0
Condo/Townhouse No Fireplaces — 6 58
Condo/Townhouse Wood Mass lb/year 1,019 0
Appendix A 38
462
15 Argonaut Custom Report, 5/12/2026
39 / 39
Condo/Townhouse Wood Mass lb/year 1,000 0

8.5.3. Energy Usage
Land Use Model Parameter Units Default Value New Value
Condo/Townhouse Electricity kWh/yr 266,346 422,250
Condo/Townhouse Electricity (Subject to Title 24) kWh/yr 65,650.4 180,142 Condo/Townhouse Electricity (Not Subject to Title 24) kWh/yr 200,695 242,108 Condo/Townhouse Natural Gas kBTU/yr 1,393,761 0.00000
Condo/Townhouse Natural Gas (Subject to Title 24) kBTU/yr 1,241,553 0.00000 Condo/Townhouse Natural Gas (Not Subject to Title 24) kBTU/yr 152,208 0.00000 Appendix A 39
463
15 Argonaut
Construction -Material Movement
Calculations:

Description Building Footprint (sf) Building footprint (sq yards) Foundation Depth (yards) Excavation (cubic yards) Additional 20%* Building Footprint 42933 4770.333333 0.33 1574.21 1889.052 Notes:

1. Assumptions: 12" foundation pursuant to the California Building Code Section R301 to calculate soil cut and export.

2. *Applied an additional 20% to model a worst-case, conservative scenario.

Appendix A 40
464
15 Argonaut
Construction - Demolition
Description
Area
(sq ft)
height/depth
(ft)
Volume
(ft3)
Demolition Waste
Fraction
Demolition
Volume (ft3)
Demolition Waste
Density (tons/cy)
Demolition Weight
(tons)
Buildings 41,519 10 415,190 0.25 103,798 0.50 1,922
Pavement 3,348 1 3,348 1 3,348 2.025 251
2,173
Notes:

1. Assumptions: Building demolition estimates are based on methods used in CalEEMod (CAPCOA, 2022), based on 1 story building , assume 10 ft per floor where 1 square ft floor area = 10 cubic ft (ft3 ) of building volume, and 1 ft3 of building volume
= 0.25 ft3
of waste. This approach can be used to estimate demolition for multiple story buildings. It also assumes 1 cubic yard (cy) building waste = 0.5 ton weight

2. Assumptions: 1 cubic yard of asphalt = 2.025 tons or 4050 lbs.

Totals

3. Source: ICF in collaboration with Sacramento Metropolitan Air Quality Management District, Fehr & Peers, STI and Ramboll. 2022. CalEEMod Appendix C Emission Calculation Details for CalEEMod. April.

Appendix A 41
465
15 Argonaut
Construction - Pavement Trips
Calculations: Asphalt Pavement Vendor Trips
Landuse
Asphalt Paved Area Asphalt Paved Area (sf) Asphalt volume (cubic feet) Asphalt Volume (cy) Capacity per vendor truck (cy per truck) One Way Trips Total Days in Paving Phase One Way Vendor Trips Per Day (Asphalt) Condo/Townhouse 50,589 25,295 937 16 118 26 5
Notes:

1. Assumptions: Asphalt paved areas includes driveways

2. Assumptions: Asphalt volume (cubic feet) assumes 6 inch pavement Appendix A 42
466
15 Argonaut
Measure E-15 All-Electric
7 Land Use Subtype Size Units Total Title 24 Non Title 24 Water Heater Primary Heat Cooking Dryer Condo/Townhouse 58 Dwelling Units 4,592 1,132 3,460 1,365 609 292 422 Notes:

Source: CalEEMod Table G-28. Annual Energy Use by Land Use Subtype and EDFZ . Recreational Pool building assigned Health Club Usage Land Use Subtype Size Units Total Title 24 Non Title 24 Water Heater Primary Heat Cooking Dryer Condo/Townhouse 58 Dwelling Units 266,346 65,650 200,695 79,170 35,322 16,936 24,476 Notes:

Source: CAPCOA GHG Handbook, Table E 15.1 and 2. Commercial Energy Consumption by End Use,1 Electricity Demand Forecast Zone, and Building Type Handbook for Analyzing Greenhouse Gas Emission Reductions, Assessing Climate Vulnerabilities, and Advancing Health and Equity. Available at: Available at: https://www.airquality.org/ClimateChange/Documents/Final%20Handbook_AB434.pdf.

Building Type / LandUse Amount Units Total Title 24 Non Title 24 Condo/Townhouse 58 Dwelling Units 422,250 180,142 242,107 Additional electricity use per Unit
for equivalent electrified end uses
Title 24 Non Title 24
CalEEMod Defaults
Baseline Annual Energy Usage for Project Landuse

for equivalent electrified end uses
Title 24 Non Title 24
CEC Electricity Demand Forecast Zone (EDFZ)
Adjustment for Measure E-15
Annual Electrical Usage (kWhr)
Per Unit
Annual Energy Use by Land Use Subtype and EDFZ1
Appendix A 43
467
15 Argonaut
Construction Energy
Scenario: Unmitigated (5.2.1 / 5.3.1)
Sources
Field Value
Project Name 15 Argonaut
County Orange
EMFAC Region Orange
Construction Year 2027
CalEEMod Version 2022.1.1.43
CalEEMod workbook 15 Argonaut (3).xlsx
EMFAC Annual CSV EMFAC2025EI-EMFAC2007Class-Orange-2027-Annual-20260512134437.csv Off-road sheet used 5.2.1
Vehicles sheet used 5.3.1
Off‑Road BSFC (gal/bhp‑hr) 0.054
Referenced CalEEMod Sections 5.1 Schedule; 5.2.x Off‑Road; 5.3.x Construction Vehicles Methods & Assumptions
EMFAC Region: Orange; Construction Year: 2027.

Off‑road equipment fuel uses BSFC applied to HP × load × hours × work days by phase (liquid fuels in gallons; electric in kWh).

On‑road construction trips apply EMFAC fuel consumption factors (gal/mi) to allocated VMT (vehicles are liquid‑only in this app; no EVMT/kWh/mi).

Totals report liquid fuels in gallons and off‑road electric in kWh.
•
•
•
•
Appendix A 44
468
Off‑Road Equipment — Estimated Fuel Consumption
Phase Name Equipment Type Qty/Day HP Load Factor Hours/Day hp-hr/day Work Days Fuel Est. gallons Demolition
Concrete/Industrial Saws 1 33 0.73 8 193 26 Diesel 271
Excavators 3 36 0.38 8 328 26 Diesel 461
Rubber Tired Dozers 2 367 0.40 8 2,349 26 Diesel 3,298
Site Preparation
Rubber Tired Dozers 3 367 0.40 8 3,523 13 Diesel 2,473
Tractors/Loaders/Backhoes 4 84 0.37 8 995 13 Diesel 698 Grading
Excavators 1 36 0.38 8 109 26 Diesel 154
Graders 1 148 0.41 8 485 26 Diesel 682
Rubber Tired Dozers 1 367 0.40 8 1,174 26 Diesel 1,649
Tractors/Loaders/Backhoes 3 84 0.37 8 746 26 Diesel 1,047 Building
Construction
Cranes 1 367 0.29 7 745 303 Diesel 12,190
Forklifts 3 82 0.20 8 394 303 Diesel 6,440
Generator Sets 1 14 0.74 8 83 303 Diesel 1,356
Tractors/Loaders/Backhoes 3 84 0.37 7 653 303 Diesel 10,679 Welders 1 46 0.45 8 166 303 Diesel 2,710
Paving
Pavers 1 81 0.42 8 272 26 Diesel 382
Paving Equipment 2 89 0.36 6 384 26 Diesel 540
Rollers 2 36 0.38 6 164 26 Diesel 230
Cement and Mortar Mixers 2 10 0.56 6 67 26 Diesel 94
Tractors/Loaders/Backhoes 1 84 0.37 8 249 26 Diesel 349 Architectural
Coating Air Compressors 1 37 0.48 6 107 27 Diesel 155
TOTAL 45,858
Sources: CalEEMod Section 5.1 (schedule) and CalEEMod Section 5.2 (equipment per phase, quantity/day, hours/day, horsepower, and load factor).

Notes: HP = horsepower; BSFC = Brake Specific Fuel Consumption. Fuel (gal) = Qty × HP × Load × Hours/Day → hp‑hr/day × Work days × BSFC. A BSFC factor of 0.054 gal/bhp‑hr corresponds to ~18.5 bhp‑hr/gal (CARB‑derived). Total Electricity (not shown per equipment): 0 kWh.

Appendix A 45
469
Estimated VMT and Fuel Consumption - On-Road Construction Trips Phase Name Trip Type Vehicle Mix Fuel VMT EMFAC gal/mi Est. gallons Demolition Worker LDA,LDT1,LDT2 Gasoline 7,215 0.0429 309 Demolition Vendor HHDT,MHDT Diesel 0 0.1343 0
Demolition Hauling HHDT Diesel 10,880 0.1571 1,709
Demolition Onsite Truck HHDT Diesel 0 0.1571 0
Site Preparation Worker LDA,LDT1,LDT2 Gasoline 4,209 0.0429 180 Site Preparation Vendor HHDT Diesel 530 0.1571 83
Site Preparation Hauling HHDT Diesel 0 0.1571 0
Site Preparation Onsite Truck HHDT Diesel 0 0.1571 0
Grading Worker LDA,LDT1,LDT2 Gasoline 7,215 0.0429 309
Grading Vendor HHDT,MHDT Diesel 0 0.1343 0
Grading Hauling HHDT Diesel 4,740 0.1571 745
Grading Onsite Truck HHDT Diesel 0 0.1571 0
Building
Construction Worker LDA,LDT1,LDT2 Gasoline 234,086 0.0429 10,038 Building
Construction Vendor HHDT,MHDT Diesel 19,162 0.1343 2,573 Building
Construction Hauling HHDT Diesel 0 0.1571 0
Building
Construction Onsite Truck HHDT Diesel 0 0.1571 0
Paving Worker LDA,LDT1,LDT2 Gasoline 9,620 0.0429 413
Paving Vendor HHDT Diesel 1,061 0.1571 167
Paving Hauling HHDT Diesel 0 0.1571 0
Paving Onsite Truck HHDT Diesel 0 0.1571 0
Architectural
Coating Worker LDA,LDT1,LDT2 Gasoline 4,172 0.0429 179
Architectural
Coating Vendor HHDT,MHDT Diesel 0 0.1343 0
Architectural
Coating Hauling HHDT Diesel 0 0.1571 0
Architectural
Coating Onsite Truck HHDT Diesel 0 0.1571 0
TOTAL 302,890 16,706
Appendix A 46
470
Phase Name Trip Type Vehicle Mix Fuel VMT EMFAC gal/mi Est. gallons Sources: CalEEMod Section 5.1 (# of work days per phase) and CalEEMod Section 5.3 (trip type, vehicle mix, and VMT).

Notes: VMT = vehicle miles traveled; mpg = miles per gallon. VMT was derived as one‑way trips per day × miles per one-way trip Estimated gallons for on‑road trips: Fuel (gal) = VMT × EMFAC gal/mi. EMFAC gal/mi factors originate from CARB’s EMFAC model for the applicable county and construction year.

Appendix A 47
471
EMFAC Fuel Consumption Rates by Vehicle Mix (County = Orange; Calendar Year=2027) Vehicle Category Diesel (gal/mi) Gasoline (gal/mi)
HHDT 0.1571 —
MHDT 0.1115 —
LDA — 0.0373
LDT1 — 0.0450
LDT2 — 0.0442
Notes: Fuel consumption from EMFAC2021v1.0.2
CalEEMod Vehicle Mix – EMFAC Rates
Vehicle Mix Fuel gal/mi
LDA,LDT1,LDT2 Gasoline 0.0429
HHDT,MHDT Diesel 0.1343
Notes: Light-duty=25/50/25; Heavy-duty (HHDT,MHDT)=50/50.

Appendix A 48
472
Totals Summary
Metric Value
Total estimated gallons — On‑road 16,706
Total estimated gallons — Off‑road (liquid fuels) 45,858 Total estimated kWh — Off‑road (electric) 0
Grand total (reporting note) Liquid fuels in gallons; electric in kWh County (CalEEMod 1.1) Orange
EMFAC Region Orange
Year (from 1.1 Construction Start Date) 2027
Notes: Scenario codes shown above (e.g., 5.2.1/5.3.1 or 5.2.2/5.3.2).

Appendix A 49
473
15 Argonaut
Operational Energy
Scope: Full (Vehicles + Buildings + Stationary)
Sources
Field Value
Project Name 15 Argonaut
County Orange
EMFAC Region Orange
Op Year 2028
CalEEMod Version 2022.1.1.43
CalEEMod workbook 15 Argonaut (3).xlsx
EMFAC Annual CSV EMFAC2025EI-EMFAC2007Class-Orange-2028- Annual-20260512134451.csv
Land Use Sheet 1.2
Mobile Source Sheet 5.9.1
Operational Energy consumption sheet 5.11.1
Building Energy Title 24 and Non‑Title 24 (overrides)
Sheet 8.5.3
Methods & Assumptions
Mobile energy is calculated as: Annual VMT by land use (CalEEMod 5.9.1) × vehicle‑class mix (CalEEMod 8.5.1.2, Annual/ Season A when provided; otherwise EMFAC population mix) × EMFAC effective per‑mile energy rates.

Plug‑in hybrids contribute to both gasoline and electricity buckets per EMFAC fuel/energy accounting. “Natural Gas” in EMFAC is reported in diesel‑equivalent gallons and is included in the CNG totals.

Building energy (CalEEMod 5.11.1) and Title 24 / Non‑Title 24 overrides (CalEEMod 8.5.3) are shown separately from mobile energy.

Off‑road (5.15.1 / 5.15.2) hp‑hr/yr = HP × Load Factor × Hours/Day × Number/Day × Days/Year (assumed 260) and converted using construction‑style factors; Generators/Fire Pumps (5.16.1) use Hours/Year.

All reported values are annual totals: electricity (kWh/yr), natural gas (kBTU/yr), and liquid fuels (gallons/yr; diesel‑equivalent gallons for CNG).
•
•
•
•
•
•
Appendix A 50
474
Project Land Uses and Descriptions
Land Use Subtype Size Unit Description
Condo/Townhouse 58 Dwelling Unit
Source: CalEEMod worksheet 1.2).

Trips by Land Use
Land Use Description Trips (Weekday) Trips (Saturday) Trips (Sunday) Trips (Year) Condo/Townhouse 356 356 356 129,940
TOTAL 356 356 356 129,940
CalEEMod Section 5.9.1.

VMT by Land Use
Land Use Description VMT (Weekday) VMT (Saturday) VMT (Sunday) VMT (Year) Condo/Townhouse 3,145 3,145 3,145 1,147,950
TOTAL 3,145 3,145 3,145 1,147,950
CalEEMod Section 5.9.1.

Appendix A 51
475
CalEEMod Fleet by Land Use (Percent of Annual VMT)
Land Use Description HHDT LDA LDT1 LDT2 LHDT1 LHDT2 MCY MDV MH MHDT OBUS SBUS UBUS Condo/Townhouse 0.67 45.82 3.96 25.43 2.59 1.15 2.31 15.97 0.44 1.45 0.06 0.09 0.05 Notes:

1. Fleet mix values represent the percentage of annual VMT allocated to each vehicle class for each land use, and percentages sum to 100% across all classes.

2. Where available, CalEEMod 8.5.1.2 (Annual/Season A) fleet mix is used; otherwise EMFAC default fleet population mix is used.

3. Vehicle class abbreviations follow standard EMFAC conventions (e.g., LDA = Light‑Duty Auto; HHDT = Heavy‑Heavy‑Duty Truck; MCY = Motorcycle).

Appendix A 52
476
EMFAC Technology Parameters by Vehicle Category
Vehicle Category Fuel/Tech gal/mi kWh/mi CVMT frac EVMT frac within-class share HHDT
Diesel 0.154 — 1 — 0.938
Electricity — 1.79 — 1 0.004
Fuel Cell Electric Vehicle — 0 — 1 0.000
Gasoline 0.258 — 1 — 0.001
Natural Gas 0.155 — 1 — 0.057
LDA
Diesel 0.0269 — 1 — 0.001
Electricity — 0.332 — 1 0.153
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.0368 — 1 — 0.737
Plug-in Hybrid 0.0359 0.367 0.393 0.607 0.108
LDT1
Diesel 0.0439 — 1 — 0.000
Electricity — 0.374 — 1 0.129
Gasoline 0.0446 — 1 — 0.774
Plug-in Hybrid 0.036 0.429 0.460 0.540 0.097
LDT2
Diesel 0.0337 — 1 — 0.002
Electricity — 0.415 — 1 0.013
Gasoline 0.0435 — 1 — 0.870
Plug-in Hybrid 0.0361 0.489 0.467 0.533 0.116
LHDT1
Diesel 0.0469 — 1 — 0.326
Electricity — 0.564 — 1 0.010
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.0668 — 1 — 0.663
LHDT2
Diesel 0.0524 — 1 — 0.697
Electricity — 0.564 — 1 0.014
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.0719 — 1 — 0.288
MCY Gasoline 0.0248 — 1 — 1
Appendix A 53
477
Vehicle Category Fuel/Tech gal/mi kWh/mi CVMT frac EVMT frac within-class share MDV
Diesel 0.0403 — 1 — 0.032
Electricity — 0.496 — 1 0.077
Gasoline 0.0533 — 1 — 0.849
Plug-in Hybrid 0.0365 0.611 0.475 0.525 0.042
MH
Diesel 0.0987 — 1 — 0.333
Gasoline 0.205 — 1 — 0.667
MHDT
Diesel 0.111 — 1 — 0.660
Electricity — 1.25 — 1 0.016
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.186 — 1 — 0.318
Natural Gas 0.117 — 1 — 0.006
OBUS
Diesel 0.133 — 1 — 0.416
Electricity — 1.24 — 1 0.071
Fuel Cell Electric Vehicle — 0 — 1 0.002
Gasoline 0.193 — 1 — 0.431
Natural Gas 0.00327 — 1 — 0.080
SBUS
Diesel 0.135 — 1 — 0.225
Electricity — 1.37 — 1 0.026
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.107 — 1 — 0.372
Natural Gas 0.233 — 1 — 0.376
UBUS
Electricity — 2.13 — 1 0.140
Fuel Cell Electric Vehicle — 0 — 1 0.001
Gasoline 0.13 — 1 — 0.305
Natural Gas 0.222 — 1 — 0.554
Note: Fractions & shares from EMFAC class/fuel VMT.

Appendix A 54
478
Annual Mobile Energy Consumption by Land Use
Land Use Description Gasoline (gal/yr) Diesel (gal/yr) CNG (gal/yr) Electricity (kWh/yr) Condo/
Townhouse 40,826 3,775 235 63,330
TOTAL 40,826 3,775 235 63,330
Computed from VMT, fleet mix, and EMFAC effective class rates. EMFAC population mix was used for land uses without 8.5.1.2 entries. EMFAC 'Natural Gas' is reported in diesel‑equivalent gallons and is included in the CNG totals.

Appendix A 55
479
Annual Building Energy by Land Use
Land Use Description Electricity (kWh/yr) Natural Gas (kBTU/yr) Condo/Townhouse 422,250 0
TOTAL 422,250 0
Note: Annual electricity and natural gas usage from CalEEMod Section 5.11.1.

Title 24 / Non-Title-24 Energy Consumption by Land Use
Land Use Description Elec T24 (kWh) Elec Non‑T24 (kWh) NG T24 (kBTU) NG Non‑T24 (kBTU) Condo/Townhouse 180,142 242,108 0 0
Note: Energy usage adjustments from CalEEMod Section 8.5.3.

Appendix A 56
480
FCS
Appendix B:

Biological Resources Supporting
Information
•• • FCS
An ADEC Innovation
481

THIS PAGE INTENTIONALLY LEFT BLANK
482
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Table 1: Special-status Plant Species Potentially Occurring within the Project Site Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Dicots
Abronia maritima
red sand-verbena
— — 4.2 Perennial herb found in coastal dunes.

Elevation: 0–100 m
Bloom period: February–November
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Aphanisma blitoides
aphanisma
— — 1B.2 Annual herb found in gravelly (sometimes)
and sandy (sometimes) soils in coastal bluff
scrub, coastal dunes, and coastal scrub.

Elevation: 1–305 m
Bloom period: February–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
three recent and three historical records
between five and ten miles from the project
site.

No
Artemisia palmeri
San Diego sagewort
— — 4.2 Perennial deciduous shrub found in mesic
and sandy soils in chaparral, coastal scrub,
riparian forest, riparian scrub, and riparian
woodland.

Elevation: 5–915 m
Bloom period: May–September
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Astragalus brauntonii
Braunton's milk-vetch
FE — 1B.1 Perennial herb found in carbonate and
sandstone soils in chaparral, coastal scrub,
and valley and foothill grassland
communities. Typically found in burned areas
and sometimes in disturbed areas.

Elevation: 4–640 m
Bloom period: January–August
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one recent record between five and ten miles
from the project site.

No
483
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Atriplex coulteri
Coulter’s saltbush
— — 1B.2 Perennial herb found in alkaline or clay soils (sometimes) in coastal bluff scrub, coastal
dunes, coastal scrub, and valley and foothill
grassland communities.

Elevation: 3–460 m
Bloom period: March–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
three historical records within five miles of the
project site and there are three recent and
eight historical records between five and ten
miles from the project site.

No
Atriplex pacifica
south coast saltscale
— — 1B.2 Annual herb found in coastal bluff scrub,
coastal dunes, coastal scrub, and playas.

Elevation: 0–140 m
Bloom period: March–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
two historical records within five miles of the
project site and one recent and two historical
records between five and ten miles from the
project site.

No
Atriplex parishii
Parish’s brittlescale
— — 1B.1 Annual herb found in alkaline soils in
chenopod scrub, playas, and vernal pools.

Elevation: 25–1900 m
Bloom period: June–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one historical record within five miles of the
project site. This species may be locally
extirpated.

No
Atriplex serenana var.
davidsonii
Davidson’s saltscale
— — 1B.2 Annual herb found in alkaline soils in coastal bluff scrub and coastal scrub.

Elevation: 10–200 m
Bloom period: April–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one record within five miles of the project site
No
484
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
and three historical records between five and
ten miles from the project site.

Bahiopsis laciniata
San Diego County viguiera
— — 4.3 Perennial shrub found in chaparral and
coastal scrub.

Elevation: 60–750 m
Bloom period: February–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Berberis nevinii
Nevin's Barberry
FE SE 1B.1 Perennial, evergreen shrub found on steep,
north-facing slopes or in low-grade sandy
washes in coastal scrub, chaparral,
cismontane woodland, and riparian scrub
communities.

Elevation: 290–1,575 m
Blooming period: March–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Camissoniopsis lewisii
Lewis’ evening-primrose
— — 3 Annual herb found in clay and sandy soils
(sometimes) in coastal bluff scrub,
cismontane woodland, coastal dunes, coastal
scrub, and valley and foothill grassland
communities.

Elevation: 0–300 m
Bloom period: March–May
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Caulanthus simulans
Payson's jewelflower
— — 4.2 Annual herb found in granitic and sandy soils
in chaparral and coastal scrub communities.

Elevation: 90–2,200 m
Bloom period: March–May
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Centromadia parryi ssp.
australis
southern tarplant
— — 1B.1 Annual herb found in marshes and swamps
(margins), valley and foothill grassland
(vernally mesic), and vernal pools.

Elevation: 0–480 m
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
No
485
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Bloom period: May–November one recent record within five miles of the project site and six recent and thirteen
historical records between five and ten miles
from the project site.

Chaenactis glabriuscula
var. orcuttiana
Orcutt's pincushion
— — 1B.1 Annual herb found in coastal bluff scrub
(sandy) and coastal dunes.

Elevation: 0–100 m
Bloom period: January–August
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one historical record within five miles of the
project site and one recent and two historical
records between five and ten miles from the
project site.

No
Chloropyron maritimum
salt marsh bird’s-beak
FE SE 1B.2 Annual, hemiparasitic herb found in coastal
dunes, marsh and swamp, salt marsh, and
wetlands communities.

Elevation: 0–30 m
Bloom period: May–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one recent record between five and ten miles
from the project site.

No
Chorizanthe leptotheca
Peninsular spineflower
— — 4.2 Annual herb found in granitic soils in
chaparral, coastal scrub, and lower montane
coniferous forest communities.

Elevation: 300–1,900 m
Bloom period: May–August
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Chorizanthe polygonoides
var. longispina
long-spined spineflower
— — 1B.2 Annual herb that occurs in valley and foothill grassland, coastal scrub, chaparral, meadows
and seeps, and vernal pools.

Elevation: 30–1,530 m
Bloom period: April–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
486
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Cistanthe maritima
seaside cistanthe
— — 4.2 Annual herb found in sandy soils in coastal
bluff scrub, coastal scrub, and valley and
foothill grassland.

Elevation: 5–300 m
Bloom period: March–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Clinopodium chandleri
San Miguel savory
— — 1B.2 Perennial shrub found in chaparral,
cismontane woodland, coastal scrub, riparian
woodland, and valley and foothill grassland.

Sometimes in gabbroic and rocky soils.

Elevation: 120–1,075 m
Bloom period: March–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one record between five and ten miles from
the project site.

No
Comarostaphylis
diversifolia ssp. diversifolia
summer holly
— — 1B.2 Perennial evergreen shrub found in chaparral
and cismontane woodland.

Elevation: 30–790 m
Bloom period: April–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
one recent and five historical records
between five and ten miles from the project
site.

No
Convolvulus simulans
small-flowered morningglory
— — 4.2 Annual herb found in clay soils, seeps, and
serpentine soils in openings in chaparral,
coastal scrub, and valley and foothill
grassland communities.

Elevation: 30–740 m
Bloom period: March–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Deinandra paniculata
paniculate tarplant
— — 4.2 Annual herb found in sandy soils (sometimes)
and in vernally mesic soils (usually) in coastal
scrub, valley and foothill grassland, vernal
pool communities.

None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
487
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Elevation: 25–940 m
Bloom period: April–November
Dichondra occidentalis
western dichondra

CONCCP/
HCP

CONCCP/
HCP

4.2 Perennial rhizomatous herb found in
chaparral, cismontane woodland, coastal
scrub, and valley and foothill grassland
communities.

Elevation: 50–500 m
Bloom period: March–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Diplacus clevelandii
Cleveland's bush
monkeyflower
— — 4.2 Perennial rhizomatous herb found in
chaparral, cismontane woodland, and lower
montane coniferous forest. In disturbed
areas, gabbroic soils, openings, and rocky
areas.

Elevation: 450–2,000 m
Bloom period: April–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Dudleya blochmaniae ssp.
blochmaniae
Blochman's dudleya

CONCCP/
HCP

CONCCP/
HCP
1B.1 Perennial herb found in clay (often), rocky,
and serpentine soils in coastal bluff scrub,
chaparral, coastal scrub, and valley and
foothill grassland.

Elevation: 5–450 m
Bloom period: April–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
four historical records between five and ten
miles from the project site.

No
Dudleya chasmophyta
Santiago Canyon dudleya
— — 1B.1 Perennial herb found in rocky soils and steep
cliffs of conglomerate rock in chaparral and
coastal scrub communities.

Elevation: 475–515 m
Bloom period: May–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
488
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Dudleya multicaulis
many-stemmed dudleya
— — 1B.2 Perennial herb found in clay soils (usually) in chaparral, coastal scrub, and valley and
foothill grassland communities.

Elevation: 15–790 m
Bloom period: April–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
three recent and 22 historical records within
five miles of the project site and eight recent
and eighteen historical records between five
and ten miles from the project site.

No
Dudleya stolonifera
Laguna Beach dudleya
FT

CONCCP/
HCP
CT

CONCCP/
HCP
1B.1 Perennial stoloniferous herb found in rocky
soils in chaparral, cismontane woodland,
coastal scrub, and valley and foothill
grassland communities.

Elevation: 10–260 m
Bloom period: May–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one recent record within five miles of the
project site.

No
Dudleya viscida
sticky dudleya
— — 1B.2 Perennial herb found in rocky areas in coastal bluff scrub, chaparral, cismontane woodland,
and coastal scrub.

Elevation: 10–550 m
Bloom period: May–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one historical record between five and ten
miles from the project site.

No
Eryngium pendletonense
Pendleton button-celery
— — 1B.1 Perennial herb found in clay and vernally
mesic soils in coastal bluff scrub, valley
foothill grassland, and vernal pools.

Elevation: 15–110 m
Bloom period: April–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Erythranthe diffusa
Palomar monkeyflower
— — 4.3 Annual herb found in gravelly and sandy soils
(sometimes) in chaparral and lower montane
coniferous forest communities.

None: The project site has been subjected to
significant historical surface disturbances and
No
489
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Elevation: 1,220–1,830 m
Bloom period: April – June
does not contain suitable habitat(s) that would
support occurrence of this species.

Euphorbia misera
Cliff spurge

CONCCP/
HCP

CONCCP/
HCP
2B.2 Perennial shrub found in rocky soils in coastal
bluff scrub, coastal scrub, and Mojavean
desert scrub.

Elevation: 10–500 m
Bloom period: December–August
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
two recent and two historical records between
five and ten miles from the project site.

No
Harpagonella palmeri
Palmer’s grapplinghook

CONCCP/
HCP

CONCCP/
HCP

4.2 Annual herb found in clay soils and openings
in chaparral, coastal scrub, and valley and
foothill grassland communities.

Elevation: 20–955 m
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one historical record between five and ten
miles from the project site.

No
Helianthus nuttallii ssp.
parishii
Los Angeles sunflower
— — 1A Perennial rhizomatous herb found in marshes
and swamps (freshwater, coastal salt).

Elevation: 10–1525 m
Bloom period: August–October
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one historical record between five and ten
miles from the project site.

No
Holocarpha virgata ssp.
elongata
graceful tarplant
— — 4.2 Annual herb found in chaparral, cismontane
woodland, coastal scrub, and valley and
foothill grassland.

Elevation: 60–1,100 m
Bloom period: May–November
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Horkelia cuneata var.
puberula
mesa horkelia
— — 1B.1 Perennial herb found in chaparral, coastal
scrub, and cismontane woodland
communities.

None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
No
490
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Bloom period: February–July
Elevation: 70–810 m
Bloom period: March–May
support occurrence of this species. There is
one historical record within five miles of the
project site and one historical record between
five and ten miles from the project site.

Isocoma menziesii var.
decumbens
decumbent goldenbush
— — 1B.2 Perennial shrub found in chaparral and
coastal scrub (often disturbed areas, sandy).

Elevation: 10–250 m
Bloom period: April–November
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There is
one recent and one historical record between
five and ten miles from the project site.

No
Juglans californica
southern California black
walnut
— — 4.2 Perennial, deciduous tree found in chaparral,
cismontane woodland, coastal scrub, and
riparian woodland communities.

Elevation: 50–900 m
Bloom period: March–August
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Lasthenia glabrata ssp.
coulteri
Coulter’s goldfields
— — 1B.1 Annual herb found in marshes and swamps,
playas, and vernal pools.

Elevation: 1–1,220 m
Bloom period: February–June
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species. There are
three historical records between five and ten
miles from the project site.

No
Lepechinia cardiophylla
heart-leaved pitcher sage

CONCCP/
HCP

CONCCP/
HCP
1B.2 Perennial shrub found in closed-cone
coniferous forest, chaparral, and cismontane
woodland communities.

Elevation: 520– 1,370 m
Bloom period: April–July
None: The project site has been subjected to
significant historical surface disturbances and
does not contain suitable habitat(s) that would
support occurrence of this species.

No
Lepidium virginicum var.
robinsonii
— — 4.3 Annual herb found in dry soils in chaparral
and coastal scrub communities.

None: The project site has been subjected to
significant historical surface disturbances and
No
491
CITY OF ALISO VIEJO — 1 5 ARGONAUT P ROJECT

BIOLOGICAL RESOURCES ASSESSMENT APPENDIX B
FCS
Scientific Name
Common Name
Status
Habitat Description4 Potential to Occur and Rationale5
Included in
Impact
USFWS Analysis 1 CDFW2 CNPS3
Robinson’s pepper-grass Elevation: 1–855 m
Bloom period: January–July
does not contain suitable habitat(s) that would
support occurrence of this species. There are
two recent and two historical records between
five and ten miles from the project site.

Lessingia hololeuca
woolly-headed lessingia
— — 3 Annual herb found in clay and serpentine
soils in broadleafed upland forest, coastal
scrub, lower montane coniferous forest, and
valley and foothill grassland.