Belmont City Council
February 13, 2024

WHEREAS, the Planning Commission further finds that the applicants have demonstrated that adequate financing is available to construct and maintain the road as proposed:

1. The property owner/applicant will post a bond to ensure completion of the proposed road, and the adjoining property owners with road frontage will have reciprocal obligation to maintain the improved road under California Civil Code Section §845 until such time as the city council formally accepts the road into the city street system consistent with California Streets and Highways Code Section § 1806.

WHEREAS, the Planning Commission further finds that access to abutting properties has been adequately considered in the design of the road improvements, in that:

1. The access rights of abutting property owners to their properties will be maintained.

WHEREAS the Planning Commission recommends the City Council approve the project provided that the Geotechnical Engineer of Record (GEOR) provides an updated letter to the project Geotechnical Investigation report addressing the 2018 Seismic Hazards Map Act (SHMA) requirements, and the City Council receive a peer review letter confirming the SHMA requirements have been satisfactorily addressed by the GEOR and that seismic slope stability issues would not preclude development of the project.

WHEREAS the Planning Commission did hear and use their independent judgment and considered all said reports, recommendations and testimony herein above set forth.

NOW, THEREFORE, BE IT RESOLVED that the Planning Commission recommends City Council approval of the Hillside Road Improvement Plan, Single-Family Design Review, Floor Area Transfer, Conditional Use Permit, Grading Permit, Tree Removal Permit, and Belmont City Code Exceptions for the subject project subject to the attached conditions in Exhibit "A", and based upon the following findings:

Environmental Review
The proposed new single-family home is categorically exempt from the provisions of the California Environmental Quality Act by provision of Section 15303, Class 3(a):
"Class 3 consists of construction and location of limited numbers of new, small facilities or structures ... Examples of this exemption include but are not limited to:
(a) One single-family residence, or a second dwelling unit in a residential zone. In urbanized areas, up to three single-family residences may be constructed or converted under this exemption.
(d) Water main, sewage, electrical, gas, and other utility extensions, including street improvements, of reasonable length to serve such construction. (e) Accessory (appurtenant) structures including garages, ca,ports, patios, swimming pools, and fences."
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The project proposal includes the construction of a single-family home, a road extension to serve said single-family home and provide adequate emergency services access to the site, and the installation of associated landscaping features, including retaining walls, and utilities extensions. The proposed project would qualify for a Class 3 exemption under items (a) and (d), as it would involve the construction of one single-family residence; associated water main, sewage, electrical, gas, and storm drain utility extensions; and street improvements (i.e., a road extension) designed to serve the residence and comply with the City's municipal code requirements.

Class 32 Exemption- In-Fill Development Projects
Projects falling under the 15332 exemption are considered Class 32 projects. Class 32 projects are characterized as in-fill development meeting the conditions listed below:
(a) The project is consistent with the applicable general plan designation and all applicable general plan policies as well as with applicable zoning designation and regulations. (b) The proposed development occurs within city limits on a project site of no more than five acres substantially surrounded by urban uses.
(c) The project site has no value as habitat for endangered, rare, or threatened species. (d) Approval of the project would not result in any significant effects relating to traffic, noise, air quality, or water quality.

The project qualifies as Categorically Exempt under the California Environmental Quality Act (CEQA), Section 15332 ("In-Fill Development Projects") because it is characterized as an in-fill development which is consistent with the applicable General Plan and zoning designation; is on a project site that is less than five acres; contains no value as habitat for endangered, rare, or threatened species; would not result in any significant effects relating to traffic, noise, air quality, or water quality; and the site can adequately be served by all required utilities and public services.

Based on the information provided in the Categorical Exemption Evaluation in Exhibit "B", the proposed project qualifies for a categorical exemption under CEQA Sections 15303 (a) and (d), New Construction or Conversion of Small Structures, and Section 15332, In-Fill Development Projects.

Hillside Road Improvement Plan
To adopt a hillside road improvement plan, the Planning Commission must make a recommendation to the City Council regarding each of the following findings as per Belmont City Code Section 7-

13.e.10 (a-h):
(a) The road improvement plan is consistent with the purposes and policies of the San Juan Hills Area Plan.

The goals of the San Juan Hills Area Plan (SJHAP) are implemented by the policies of the SJHAP.

The SJHAP establishes policies for unimproved roadways in subdivided areas. The following is an analysis of the project's conformance with specific Area Plan Road policies. 301
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San Juan Hills Area Plan Applicable Policies
Infrastructure - Policy 9: Minimize Road Improvements to Protect Natural Resources. This policy encourages avoidance of steep slopes, stands of substantial trees and creeks/riparian corridors in order to minimize road improvements to protect natural resources. The proposed roadway is sized and located to minimize its effects on steep slopes, avoids trees and does not cross any creeks or riparian corridors. No protected trees are anticipated to be removed with development of the proposed road extension.

Infrastructure - Policy 10: Require Overall Road Improvement, Plans and Financing Prior to Granting any Building Permits on Unimproved Roads. This policy requires property owners to resolve design and financing of road improvements along the entire unimproved road on which their property is located prior to receiving a building permit for a new structure or of enlargement of an existing structure. There are two possible methods of accomplishing this objective: A) submitting a plan for improving the entire roadway with an acceptable design, geotechnical, and financing information for approval by the City; or B) submitting a plan for improving a section of a roadway between an existing paved road and an area where existing physical constraints (such as extremely steep slopes or moving deep landslides) make further road extensions infeasible or undesirable.

If option B is chosen, the applicant must submit 1) A roadway design plan; 2) Evidence that the road will be geologically safe, 3) A method and timetable for financing, 4) A method and financing for maintenance if the road is to be maintained as a private road, and 5) A plan to access properties located along the rest of the unimproved road. There is a sixth provision in the policy that has been deemed unenforceable by the City; a requirement that the applicant provide the City with evidence of support by the affected landowners.

The applicant has proposed option B as noted above. According to the applicant's geotechnical engineer, with confirmation by the City's consulting geotechnical engineer through peer reviews, the proposed roadway extension is geotechnically feasible with utilization of appropriate geotechnical design criteria. The applicant, with private financing, would fund all upfront costs associated with construction. The applicant has provided the proposed plans and financing mechanisms for the road segment. The applicant intends to self-finance the design, permitting, inspection and construction.

The road extension is considered a public right-of-way and would not be a private drive. The adjoining property owners with road frontage will have reciprocal obligation to maintain the improved road until such time as the city council formally accepts the road into the city street system. A conceptual plan to access properties along the remainder of unimproved Monte Cresta was submitted with the project application. Such access, however, may not be feasible or undesirable due to geological constraints.

Infrastructure - Policy 16: Hillside Road Standards. This policy establishes four policy standards relating to hillside road standards. The standards include: a) to establish special hillside road improvement standards, including but not limited to right-of-way width, on-street parking, sidewalks, paving requirements and maximum street grade; b) to minimize the right-of-way and the paved area of the road in order to lessen the amount of grading and vegetation removal, while maintaining adequate width for emergency vehicles and required parking; c) to provide some on-street parking, 302
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and d) to consider the use of paths and narrower sidewalks as an alternative to standard sidewalks in steep areas.

One of the methods used to implement Policy 16 of the San Juan Hills Area Plan was the establishment of Hillside Road Standards as incorporated in the Belmont City Code Section 7-13.

Under those standards, in order for the City Council to adopt a plan for improvement of an unimproved road segment, a plan must include all items specified in Section 7-131(9)(a)(l-11) as well as a report signed by a licensed geotechnical engineer concluding that the physical constraints are such that a stable road cannot be reasonably constructed through to a paved road, including a description of the constraints and an evaluation of the costs and impacts of overcoming the constraints. The applicant has provided these statements consistent with the aforementioned requirement through studies and letters that were prepared by a licensed geotechnical engineer.

The project's consistency with applicable San Juan Hills Area Plan policies is further demonstrated in the Categorical Exemption Evaluation in "Exhibit "B". This finding is affirmed. (b) The proposed project provides for safe vehicular and pedestrian movement.

The proposed road design would provide adequate vehicular turnaround space, and pedestrian movement, providing a new sidewalk along the southern side of the turnaround. The San Mateo Consolidated Fire Department has reviewed the project plans and has expressed no concerns regarding emergency access to the site. This finding is affirmed. (c) The road has been designed to minimize grading and vegetation removal to the extent feasible.

Grading and vegetation removal will occur only to the extent needed to develop the road extension and infrastructure improvements. Based on the City Arborist's report, no protected trees are anticipated to be removed as part of the road construction. This finding is affirmed. (d) Drainage, erosion control and slope stability have been fully addressed in the design of the road improvements.

The applicant has submitted a C-3 Checklist, drainage study, and landscaping, grading, and drainage plans. The submitted materials identify appropriate methods to treat drainage from the roadway. The project has been reviewed and found acceptable by the City's Department of Public Works at this stage of the Development Review process. Detailed working drawings with storm water measures will be required to be submitted for review and approval as part of the building permit application process. The Department of Public Works has also reviewed the proposed storm drain impact study and drainage plans and has provided conditions of approval.

Section 7-12 of the Belmont City Code requires a determination of geotechnical hazards and preparation of geotechnical reports for proposed development activities in the San Juan Hills area prior to issuance of a building or grading permit. The area involved in the proposed hillside road improvement plan has been evaluated through geotechnical investigations conducted by licensed geotechnical engineers and peer reviewed by the City's consulting geotechnical engineer. According 303
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to the applicant's geotechnical engineer, with confirmation by the City's consulting geotechnical through peer review, the proposed roadway extension is geotechnically feasible with utilization of appropriate geotechnical design criteria. The project design and construction would be required to comply with all geotechnical recommendations contained within the project geotechnical reports and must comply with the City's building standards for development in areas that may be subject to geological hazards to receive a building permit(s). The proposed extension of Monte Cresta Drive would not extend into the adjacent areas of moderate to critical geologic hazard (identified as Pdf and Md). This finding is affirmed.
(e) The applicant has demonstrated that adequate financing is available to construct and maintain the road as proposed.

The applicant has provided the proposed plans and financing mechanisms for the road improvement.

The applicant intends to self-finance the design, permitting, inspection and construction of the roadway and enter into reimbursement agreements with the other property gaining access to their property from the road segment. Such access, however, may not be feasible due to geological constraints. At this time, copies of the reimbursement agreement have not been submitted for review and adequacy cannot be determined. Reimbursement agreements are not required as the submittal requirements for a Road Improvement Plan or the financing plan. The applicant, with private financing, would fund all upfront costs associated with construction. The property owner/applicant will be required to post a bond to ensure completion of the proposed road. The adjoining property owners with road frontage will have reciprocal obligation to maintain the improved road until such time as the city council formally accepts the road into the city street system. Maintenance will include but not be limited to retaining walls, sidewalk, curb & gutter, pavement, signs, striping and drainage improvements. This finding is affirmed.
(I) Access to abutting properties has been adequately considered in the design of the road improvements.

The project plans include provision of driveway access to the subject undeveloped lot abutting the road extension. The road extension could potentially provide access to the adjacent vacant lot to the west of the new road terminus. However, this lot is not proposed for development. In addition, this lot may not be feasible for development because of the mapped potential debris flow (PDt) and landslide movement (Pd) on the lot. This finding is affirmed. (g) If the project is for a cul-de-sac, the length and turnaround design are appropriate and consistent with emergency access requirements.

The San Mateo Consolidated Fire Department (SMCFD) and the Public Works Department has reviewed the proposed plans and determined that the length and turnaround design is appropriate with the stipulation that the turnaround includes "No Parking" and "red curb" to provide for adequate emergency access. SMCFD has expressed no concerns regarding emergency access to the site. This finding is affirmed.
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(h) If the plan is for an unimproved road segment, the City Council must have made all of the above findings in the affirmative, plus:

1. A stable, safe, through road cannot be reasonably constructed because of physical constraints; and,

2. Recommendations for access to properties abutting the part of the road which would not be improved under the plan are reasonable and consistent with the purposes and policies of the San Juan Hills Area Plan.

According to the project geotechnical engineer, with confirmation by the City's consulting geotechnical engineer through peer review, a stable, safe, through road cannot be reasonably constructed because of very significant landslide constraints. In addition, a through road would extend through geologically hazardous soils (Md and Pdf) as noted on the City's Ground Movement Potential Map, across active landslide zones and other potentially unstable areas that would hinder safe, stable through road access.

A conceptual plan to access properties along the remainder of unimproved Monte Cresta was submitted with the project application. The plan provides recommendations for access to properties abutting the part of the road which would not be improved under the plan along the route. Such access, however, may be infeasible or undesirable due to geotechnical issues and environmental conditions inconsistent with the purposes and policies of the San Juan Hills Area Plan ( e.g., excessive grading, vegetation, and tree removal). These findings are affirmed.

Residential Design Review
The required Single-Family Design Review Findings, Section 13A.5 (A-F), are made m the affirmative as follows:
(a) The buildings and structures shown on the site plan will be:
1) Designed to be compatible with any existing development on the site; 2) Located and designed to minimize disruptions of existing public views, and to protect the profile of prominent ridgelines.

Although the proposed structure would have a roof height of 28 feet, the project does not appear to disrupt any public views as assessed from Monte Cresta Drive and the surrounding streets. Given the significant downslope on-site, the bulk of the structure would be screened by the natural grade of the property. The proposal does not appear to disrupt the profile of any prominent ridgelines. This fmding is affirmed.
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(b) The overall site and building plans will achieve an acceptable balance of the following factors:

Building bulk
1) building bulk,
2) grading, including:

A) disturbed surface area, and
BJ total cubic yards, cut and fill.
3) The aesthetic impacts of hards cape as viewed from a public vantage point.

The applicant proposes to construct a contemporary multi-story home which includes a two-car garage. The building fayade would have a combination of vertical wood siding, stucco finish, metallic cladding, stone cladding, and two-sided metallic cladding and horizontal wood siding. The exterior fa�ade walls of the house would be stepped back at varying distances to break up the building mass of the dwelling. The project includes window and door detailing to help reduce building mass by breaking up the various building planes. The project will include new tree, shrub and groundcover plantings that will serve to soften the overall mass of the site development. The architectural details appear to moderate the building bulk and are appropriate for this structure and the neighborhood.

Grading/ Hardscape
Estimated earthwork quantities for the project include 150 cubic yards (CY) of cut and 650 CY of fill for the construction of the road segment, undergrounding of utilities and foundation work for the dwelling (500 CY fill-import). Hardscape visible to the surrounding area is located at the driveway/uncovered parking area and walkway/entry. The hardscape features at the front of the site are necessary to gain access and provide parking for the project. New landscaping within the front yard area would generally screen and soften these hardscape features as seen from public vantage points.

All three factors (building bulk, grading and hardscape) appear to be appropriately addressed in the building design and site/groundwork to achieve a complementary balance for the project. This finding is affirmed.
(c) All proposed accessory and support features, including driveway and parking surfaces, underfloor areas, retaining walls, utility services and other accessory structures will be integrated into the overall project design.

The proposed driveway, entry area and site retaining walls are integrated well into the overall project design. The site landscaping at the driveway will assist to conceal the understory of the driveway structure. The installation of new utilities (i.e., sewer connection, electric, etc.) to serve the dwelling would be governed by standard conditions of approval. This finding is affirmed. 306
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(d) The proposed landscape plan will incorporate:
1) Native plants appropriate to the site's environmental setting and microclimate, and 2) Appropriate landscape screening of proposed accessory and support structures.

The applicant proposes a landscape planting plan for the site that includes a variety of shrub planting (1 & 5-gallon sizes) and tree plantings (36" and 24" box size). The proposed landscape plan includes a variety of plantings in locations that would soften and screen the home and site features as seen from the street. This finding is affirmed.
(e) The project will be in substantial compliance with the Residential Design Guidelines and Residential Design Criteria as applicable.

Residential Design Criteria
The applicant has incorporated the standard of Daylight Plane to mitigate perceived building bulk at the rear elevation. The project plans effectively demonstrate that the rear elevation would fall beneath the required plane. The applicant also incorporated the standard of Prescribed Articulation to moderate building massing at the front, rear and side elevations. The building elevations will feature offset walls, decks, recessed windows, and complementary exterior building materials and that would distribute the architectural volume of the residence. The plans sufficiently demonstrate that the building elevations would be articulated beyond the minimum required amount. As such, the project is in compliance with the City's Residential Design Criteria standards.

Residential Design Guidelines
The applicant has made significant efforts to ensure the proposed dwelling would be substantially compliant with the Residential Design Guidelines. The project would maintain a consistent architectural theme and avoid mixing features of different styles, as dictated by Guideline A-1. In accordance with Guideline B-1, the project avoids flat two-story building walls and includes varying rooflines. Furthermore, the proposed design effectively minimizes the requisite grading by conforming to the natural slope of the property, thus maintaining consistency with Guideline B-3. As such, the proposal is substantially compliant with the Residential Design Guidelines. This finding is affirmed.
(I) City staff and consultants have provided technical review and conditions of approval have been adopted, as applicable, regarding project-related grading, drainage, storm-water runoff, vehicular and pedestrian access, site stability, structural encroachments, and construction impacts.

The City's consulting geotechnical engineer has provided recommendations that have been included in the Conditions of Approval. The Project Site would be graded in compliance with the City's grading ordinance and standard conditions of approval to assure that project construction and operation do not result in offsite soil or water erosion. Best Management Practices (BMP's) are a standard condition of approval which requires that soil, gravel and water do not migrate off site and cause erosion. BMP's require the use of soil and water erosion controls. Staging areas, recycling and 307
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disposal procedures and adequacy of erosion control measures will be reviewed by the Building Division as part of the structural plan check. All construction would be completed in compliance with the California Building Code and NPDES standards as administered by the City of Belmont. A condition of approval will require that a final construction management plan be reviewed and approved prior to building permit issuance. Tree protection measures have also been included as conditions of project approval. This finding is affirmed.

Floor Area Transfer
The required Conditional Use Permit Findings, Section 4. 7 .11 ( d)(3 )( a-f), are made in the affirmative as follows:
(a) The proposed transfer of density is consistent with the policies of the San Juan Hills Area Plan and the Geologic Hazards Ordinance.

The transfer is consistent with the goals of the San Juan Hills Area Plan (SJHAP). The goals in the Hillside Residential and Open Space (HROP) Areas include preserving and enhancing the present character of established residential areas. The subject receiving lot is in a residential area. The transfer of floor area will occur from two vacant "sending" lots to the receiving vacant lot. Establishment of a restrictive covenant on the sending sites will expand the more rural, open residential character of the neighborhood. In addition, the SJHAP also seeks to reflect natural constraints in land use planning by achieving a land use pattern, density and distribution of development that is consistent with the existing slopes and geologic hazards in the undeveloped parts of the San Juan Area. By establishing a restrictive covenant on the sending parcels, future development on the geologically sensitive sites will be prohibited. This finding is affirmed.
(b) Adequate infrastructure exists or its construction is assured, and for sites requiring road improvement plans, such plans have been approved.

The project site currently does not contain any utilities/ infrastructure. The applicant has submitted a road improvement plan concurrently with the subject floor area transfer application. The project proposal includes the installation of new water, sanitary sewer, electricity, and storm drain utilities.

This finding is affirmed.
(c) The pattern of development which would result from the transfer of floor area is better than could be achieved through the application of this ordinance without floor area transfer, due to less grading, less street and utility extension, and better building site locations.

The proposal would transfer floor area from two lots that is not served by adequate infrastructure and has documented landslide hazards, ultimately resulting in less development-related disturbance in the area (i.e., grading, roadway and utility extensions, and geologic hazard mitigation efforts). The proposed receiving parcel is more favorable for development given its location to infrastructure access. As such, the proposed transfer would result in a preferable building site location and a better pattern of development by allowing greater intensity where appropriate, and less intensity where it is less desirable. This finding is affirmed.
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(d) The sending property will be protected from development by the establishment of a conservation easement over its entirety, or be merged with an adjacent lot and a conservation easement established over land equal in area to the sending site, and the ownership and management of such property will be adequately provided for.

The proposal would include the recordation of a conservation easement, effectively preserving the proposed sending parcels as privately maintained open space. This finding is affirmed. (e) The proposed building sites will not be in an area designated Md or Pdf on the current geologic hazards map.

The City's Ground Movement Potential and Geologic Hazard Policy Map of the San Juan Hills Study Area identifies the receiving parcel as "Ps" and "Pfs", meaning development and roadway expansions are conditionally permitted. There is no documented portion of the proposed receiving site identified with a "Pdf' or "Md" geologic hazard. This finding is affirmed. (j) All floor area transfer standards will be met.

All requisite standards of the Floor Area Transfer, including the recordation of a conservation easement on the proposed sending parcel, would be required to be met prior to the issuance of any building permit for a project using the additional floor area granted. This finding is affirmed.

Conditional Use Permit (CUP)
The applicant has requested an exception to provisions of the Belmont Zoning Ordinance (BZO) (Section 4.7.9 "a Conditional Use Permit authorizing a smaller lot size"). The required minimum lot area established by the Belmont Zoning Ordinance (Section 4.7.9 and the Slope Density Table - 1 HRO Density and Minimum Lot Size Standards). The exceptions sought would allow the applicant to comply with all relevant Belmont Subdivision Ordinance and Zoning Ordinance standards, thus satisfying one of the conditions outlined in the Conditional Certificate of Compliance ("CCOC") issued and recorded in 2021. The CUP findings necessary for Planning Commission recommendation to the City Council for approval is in Section BZO Section 10.7.3 of the Belmont Zoning Ordinance and are provided as follows:
(1) The location of the proposed use is compatible to other land uses in the general neighborhood area and does not place an undue burden on existing transportation, utilities and service facilities in the vicinity.

The subject property was originally shown on the "Map of Subdivision No. 10, Belmont Country Club Properties, Belmont, San Mateo County, California" recorded in the Office of the Recorder of San Mateo County, California, on March 24, 1927 ("1927 Map"). By and large, the properties indicated on said map generally remain in the same configuration today. Some of the properties sold in reference to the 192 7 Map may not have been created in compliance with the Subdivision Map Act ("SMA"); however, by approving development upon those lots at some point, the City de facto 309
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"legalized" them. As such, it is fair to assume that at least some of the lots in the neighborhood were allowed to develop in the absence of compliance with the SMA.

As described in the Table below, the property does not satisfy the requisite minimum lot area. The property owner has very limited opportunities to acquire the additional land necessary to meet the requisite minimum lot area standard defined in the BZO. At the estimated 49% average slope for the subject site, the property owner would need a minimum of 403,333 square feet; a property this size would be significantly larger than any other in the neighborhood. The only avenue for meeting the standard available to the property owner would be acquiring adjacent properties to amass the necessary lot area. However, none of the HRO-2 lots sharing a border with the subject property are large enough to provide the square footage necessary; as such, the property owner would need to acquire multiple lots to obtain sufficient land area at the subject site.

Development Criteria Minimum Required Proposed
Lot Size (sq. ft.) 403,333 sq. ft.* 9,137 sq. ft**
Avg. Lot Width 60 ft. Approx. 77 ft.**
Frontage 40 ft. Approx. 64 ft.**
*Based on the BZO Sec. 4.7.9 Table 1 (HRO Density and Minimum Lot Size Standards), the subject site at 49% slope is required a minimum lot size of 403,333 sq. ft.
** Adjusted lot size and lot dimension after right-of-way dedication. I The project would involve the construction of one single-family residence. The project is an in-fill development project surrounded by existing residential uses. Thus, authorization of the requested exception (authorizing a smaller lot size) would not increase traffic and will not unduly impact utilities or services in the vicinity. This finding is affirmed.
(2) The site is of sufficient size to accommodate the proposed use together with all yards, open spaces, walls and fences, parking and loading facilities, landscaping and such other provisions required by this Ordinance.

As outlined in the paragraphs above, the history of development in the neighborhood and remaining site conditions have left the property owner with limited availability to meet the requirement of the BZO with respect to minimum lot area. However, the subject site is sufficient in size to accommodate the proposed single-family residential use. All setbacks and building height requirements will be met in accordance with the HRO-2 development standards. The project proposal will include four car offstreet parking spaces (two covered/two uncovered) in compliance with the Parking Ordinance. This finding is affirmed.
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(3) The site will be served by streets of capacity sufficient to carry the traffic generated by the proposed use.

The subject property is located in a developed residential neighborhood. The existing residential use and proposed project will not result in a change in the amount of traffic generated in the neighborhood.

The local streets are adequate to accommodate the proposed single-family residence. This finding is affirmed.
(4) The proposed use, if it complies with all conditions upon which approval is made contingent, will not adversely affect other property in the vicinity or the general welfare of the City.

The applicant has requested an exception authorizing a smaller lot size. The exception sought would allow the applicant to comply with the conditions outlined in the Conditional Certificate of Compliance ("CCOC") issued for the property in 2021. The requested an exception would not adversely affect other properties in the vicinity or the general welfare of the City. This finding is affirmed.

Grading Permit
The required Grading Permit findings, as required by Section 9-27 (a)-(h) of the City of Belmont City Code, are made in the affirmative as follows:
(a) The project will not endanger the stability of the site or adjacent properties, or pose a significant ground movement hazard to adjacent properties.

The City's Building Division and Public Works Department have reviewed the grading plans for the project and have determined that the plan is in conformity with the Building Code and the City of Belmont Grading Ordinance (Chapter 9 of the City Code). In addition, the City's standard requirements require the preparation of a site-specific geotechnical investigation, independent peer review of the investigation and incorporation of the findings of the independent peer review into the project design.

The City's consulting geotechnical engineer prepared an independent peer review of the geotechnical investigations proposed as part of the project and concurs with the characterization of the project site, findings, and design specifications. The City's consulting geotechnical engineer adds that the project geotechnical consultant shall review all plans, field work and conditions to assure that the project is built to specifications. The project geotechnical reports and the City's independent peer review requirements will, as a matter of grading and building permit procedures, be required of the project as conditions of project approval.

Based on reviews by City departments and the City's consulting geotechnical engineer, the project will not endanger the stability of the site and adjacent properties with utilization of appropriate geotechnical design criteria and drainage standards. Thus, as proposed, and conditioned, the project will not endanger the stability of the site or adjacent properties or pose a significant ground movement hazard to adjacent properties. This finding is affirmed. 311
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(b) The proposed drainage improvements, landscaping, and erosion control measures would be adequateto control erosion or flooding and would not degrade riparian habitats, stream channel capacity or water quality.

There are no streams or rivers on the site. The applicant has submitted a C-3 Checklist, drainage study, geotechnical evaluations, landscaping, grading, and drainage plans. The submitted materials identify appropriate methods to treat drainage from the site. The project has been reviewed and found acceptable by the City's Department of Public Works at this stage of the Development Review process. Detailed working drawings with storm water measures will be required to be submitted for review and approval as part of the building permit application process.

The Department of Public Works has also reviewed the proposed drainage plans and facilities and has provided conditions of approval. In addition, the City requires the implementation of Best Management Practices (BMP's) for new development and construction as part of its storm water management program, as levied through standard City conditions of project approval. For new development and construction projects, the City requires the implementation BMP's to ensure the protection of water quality in storm runoff from the project site. In brief, the measures address pollution control and management mechanisms for contractor activities, e.g., structure construction, material delivery and storage, solid waste management, employee and subcontractor training, etc.

They also provide direction for the control of erosion and sedimentation as well as the establishment of monitoring programs to ensure the effectiveness of the BMP's. The City also requires an agreement with the applicant that ensures the permanent and on-going maintenance of water quality control improvements by the applicant and/or project site owner(s).

Therefore, the proposed drainage improvements, landscaping, and erosion control measures would be adequate to control erosion or flooding and would not degrade riparian habitats, stream channel capacity or water quality. This finding is affirmed.
(c) The amount of grading proposed is necessary to allow reasonable use of the site.

A grading and drainage plan has been prepared by the project civil engineer, and grading estimates have been provided by the applicant for the project. Approximately 150 cubic yards (CY) of cut and 650 CY of fill (500 CY fill-import) would be necessary for the construction of the project. The amount of grading proposed would allowfor installation of required, storm water treatment measures, landscaping, and construction of the proposed site improvements.

Lastly, the project grading and drainage plans have been reviewed by the Department of Public Works to ensure site stability, and a standard condition of project approval would require submittal of a construction management plan for review and approval by the Community Development Department in consultation with the Fire Department, Police Department, and Department of Public Works. Said plan would, at a minimum, establish a dust control and noise control coordinator, identification of a staging area on site, and approval of a haul route. Therefore, the amount of grading proposed is necessary to allow reasonable use of the site. This finding is affirmed. 312
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( d) The proposed grading would result in a building site that is visually compatible with the surrounding land and accommodates any required off-street parking and wall landscaping.

The proposed grading does not appear to be excessive in consideration of the site conditions, and it does not appear that the project would be visually incompatible with the surrounding area, which is similarly developed with residential uses. The grading would provide for the construction of site improvements, and off-street parking consistent with the parking requirements in the Parking Ordinance. This finding is affirmed.
(e) The proposed grading will meet the standards and specifications of Article IV of Chapter 9 in the CityCode (Grading Ordinance).

Conditions of approval have been attached to the project to ensure that the final grading plan for the project will meet all of the standards contained in Article IV of Chapter 9 of the City Code (Grading Ordinance). This finding is affirmed.
(I) The Director of Public Services and the applicant's Geotechnical engineer shall find that the form of vehicular access and methods of excavation are the simplest and least intrusive possible to obtain the geologic information required by the city.

The Public Works Department has reviewed the grading plan, vehicular access, and methods of excavation and, as proposed and conditioned, found them to be adequate and complete. Conditions of approval require the final grading and drainage plans be consistent with the Public Works Department requirements for the design and construction of the site improvements. This finding is affirmed.
(g) The grading permit is conditioned on issuance of a hauling permit, if required.

A Hauling Permit is required as a condition of approval for this project. This finding is affirmed. (h) The design of the project preserves existing protected trees on the site and trees on adjoining property to the extent possible.

Development of the proposed single-family dwelling includes the removal of one protected size Coast live oak tree. The tree removal is necessary for the proposed development of the site. A site-specific arborist report was prepared for the project which includes protection measures for trees to be retained. This finding is affirmed.
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Tree Removal Permit
The Planning Commission evaluated a Tree Removal Permit proposal for the project, and recommends conditionally approving the Permit based on the balancing of the Criteria for Permit Determination set forth in Section 25-7 (b )-( c ):
(1) Blue Gum Eucalyptus (Eucalyptus globulus);
(b) "The reviewing authority shall issue a permit to remove the following trees without consideration of the criteria in subsection (c):
(2) Dwarf Blue Gum Eucalyptus (Eucalyptus globulus 'Compacta'); (3) Monterey Pine;
(4) Palm (all species);
(5) Acacia (all species);
(6) a dead tree (any species); and
(7) Any tree that a public utility is required to remove under California Public Utility Commission regulations. "
(1) Criteria Supporting Removal (2) Criteria Supporting Retention (A) The tree is: (i) in poor condition; (ii) at the relative ( A) The tree is located outside the end of its life span of the particular species; (iii) developable area of the property. diseased or infested beyond reasonable remediation; (B) The tree and its location contribute (iv) has poor structural integrity; (v) is in danger of substantially to the aesthetic appeal of falling; or, (vi) poses a safety hazard.
the property or the neighborhood.
(BJ The particular tree species is undesirable due to (C) The effect of the requested tree characteristics such as invasiveness, tendency toward removal on the remaining number, limb failure, and fire hazard.
species, size and location of existing
:
(CJ The tree is damaging or interfering with existing trees on the site and in the area, structures, site improvements, or utility services. including trees mutually dependent on (D) Removal of the tree is needed in order to construct each other for survival, structural improvements or otherwise allow conforming use of integrity or aesthetics. the property.
(E) Proximity of the tree to existing or proposed
structures.

Criteria Supporting Removals & Retention
The project includes the removal of a protected size Coast live oak tree. The arborist report and the plans submitted as part of the project indicate that the tree proposed for removal is directly impacted by project construction. As such, the tree proposed for removal are in line with criteria D supporting removal. The criteria supporting retention (A - C) does not apply. Based upon review of the arborist report, and the site and grading plans, the Planning Commission finds that the proposed tree removal ;
i
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is necessary for the construction of the project. In addition, the Commission finds that adequate arrangements would be made for the protection of trees to be retained as conditioned.

Preferred Tree Species & Conditions of Permit
The Tree Ordinance indicates that for each protected tree removed, the applicant shall plant a Preferred Species tree, minimum 15-gallon size, or pay an in-lieu planting fee. The applicant has proposed to replant two preferred species Coast live oak trees as in accordance with City Code Chapter 25 -Trees. Conditions of the project approval require the applicant to implement all tree protection measures and payment of tree removal fees.

Exceptions to Hillside Road Standards
The applicant is requesting an exception to the Road Standards to eliminate parking lanes. Pursuant to BCC 7-13(e)(7)(a-c), exceptions to any of the hillside road standards may be granted by the administrative or legislative body approving the road improvement project upon recommendation of the city engineer based on consultation with the fire chief and appropriate engineering evaluations. Staff proposes that the Planning Commission recommend that the City Council make the following findings for the exception:
(a) Granting the exception will not unduly impair vehicular or pedestrian safety, or emergency access.

The Public Works Department and the San Mateo Consolidated Fire Department (SMCFD) has reviewed the project plans and has expressed no concerns regarding emergency access. As a condition, the SMCFD is requiring the proposed turnaround to be designated as ''No Parking" and "rolled red curb" to provide for adequate emergency access. This finding is affirmed. (b) Granting the exception will result in a road improvement which is consistent with the San Juan Hills Area Plan and other city ordinances.

Granting of the exception will not result in a road improvement inconsistent with the San Juan Hills Area Plan and other city ordinances as established in the project Categorical Exemption (CE) Evaluation and the Staff Report prepared for the project. This finding is affirmed. (c) Reducing the standard is necessary to avoid excessive grading or vegetation removal or to reduce the risk of erosion, flooding or slope failure.

Due to the existing unimproved right-of-way width fronting the site, there is not adequate space to construct a larger turnaround to accommodate parking lanes and a fire truck turnaround. The construction of a larger turnaround would require right-of way dedications from the adjacent privately owned properties, resulting in additional grading ( cut and fill material), vegetation removal, construction of steep retaining walls, and additional project hardscape. This finding is affirmed. 315
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The standards for an unimproved road segment terminating in a cul-de-sac are set forth in Belmont City Code Section (BCC) 7-13(4)(i). In general, the length of a cul-de-sac may not be longer than 800 feet (from the turnaround to the open street) with a tum-around radius of 32 feet. The project proposes an 870-foot-long cul-de-sac (from the turnaround to the open street) with a turnaround radius of 29.5 feet. Longer cul-de-sacs and smaller turnarounds may be permitted by the authority approving a road improvement upon the recommendation of the city engineer based on consultation with the fire chief and specific evaluation of the following:
(1) Availability of a through connection via an emergency road.

Response. Based on the geotechnical feasibility study prepared by the project engineer (Romig Engineers Inc.) and peer reviews by the City's consulting geotechnical engineer, a through-road extension is infeasible due to geotechnical issues and environmental conditions. The project proposes a road segment with a fire truck turnaround.
(2) Number of lots/houses/occupants to be served by the cul-de-sac.

Response. The existing cul-de-sac at the terminus of Monte Cresta Drive currently serves 17 homes along the 2800 block of Monte Cresta Drive. The road extension would provide driveway access to the proposed development site, and potentially provide access to the adjacent lot west of the new road terminus.
(3) Type of construction of buildings (e.g., .fire-retardant roofs and siding, interior sprinklers).

Response. Construction for the proposed dwelling will be conditioned to meet Chapter 7 A (Materials and Construction Methods for Exterior Wildfire Exposure) of the California Building Code and that the home construction includes an automatic fire sprinkler system. (4) Water pressure and availability of a secondary water main.

Response. The project site is in a residential neighborhood surrounded by existing single-family homes with existing water service. The project would install a water supply lateral that would connect to an existing water main in Monte Cresta Drive. Water pressure for the newly installed water lines will be tested during construction of the proposed single-family home. (5) Proximity to fire station and hydrant.

Response. Fire Station #15 is located approximately 0.8 miles from the project site and a fire hydrant is proposed at the tum-around I cul-de-sac.
(6) Street width.

Response. The project will meet the hillside road width standards related to the cross slopes with the granted exception to eliminate parking lanes.
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San Mateo Consolidated Fire Department (SMCFD) and Public Works Department (PWD) has reviewed the proposed turnaround design and determined that length and turnaround design is appropriate with the stipulation that the turnaround includes ''No Parking" and "red curb" to provide for adequate emergency access.
* * * * * * * * * * * * * *
Passed and adopted at a regular meeting of the Planning Commission of the City of Belmont held on November 21, 2023, by the following vote:

AYES,
COMMISSIONERS: Gurevich, Kulich, Meier, Kramer
NOES,
COMMISSIONERS: ��------------------------- None

ABSENT,
COMMISSIONERS:-=-Ma==j=es=k=-i ____________________ _

ABSTAIN,
COMMISSIONERS: -=...c...==�--------------------- None --- R EC USED, �ONEA
S:
� �1<:S:

None
Carlos de Melo
Planning Commission Secretary
317
318
MEETING OF NOVEMBER 21, 2023
AGENDA ITEM NO. 7C
Application I.D.: PA2015-0057
Application Type: Single-Family Design Review, Hillside Road Improvement Plan, Floor Area Transfer, Conditional Use Permit, Grading Permit, and Tree Removal Permit. The project also includes requests for:) Exception to Parking Lanes under BCC Section; BCC 7-13(e)(7)(a-c) and Standards for Cul-de-sacs under BCC Section; 7-13(4)(i).

Location: 2800 block of Monte Cresta Drive
Applicant/Owner: Jeff Kraft & Angela Schmiede
APN: 043-165-180, 043-242-210 & 043-165-090
Zoning: HRO-2 - Hillside Residential and Open Space
General Plan Designation: HROP (Hillside Residential and Open Space) Environmental Determination: Categorically Exempt, CEQA Guidelines Section 15303 (a), (d), & (e), New Construction or Conversion of Small
Structures, and Section 15332, In-Fill Development Projects.

PROJECT SUMMARY
Overview
The applicant proposes to construct a 3,299 square-foot multi-story residence with an attached garage, including a driveway extending from the terminus of Monte Cresta Drive. The proposed construction also includes a road segment extending Monte Cresta Drive with a fire truck turn-around/cul-de-sac at the western terminus of Monte Cresta Drive, requiring construction of retaining walls and drainage control measures. A roadway extension is required to comply with the Americans with Disabilities Act (ADA) and design standards of the City’s Hillside Road Standards – San Juan Hills, as specified in Section 7-13 of the City Code. The applicant also requests a Conditional Use Permit requesting a smaller lot size pursuant to Belmont Zoning Ordinance 4.7.9 to bring the property into compliance with the Subdivision Map Act.
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Project Location/Setting
The project site is located in western Belmont at the western terminus of Monte Cresta Drive, adjacent to 2817 Monte Cresta Drive. The site is a steeply sloping 0.22-acre parcel (Assessor Parcel Number (APN) 043-165-180 Lot 55) bounded by the residence at 2817 Monte Cresta Drive to the east, the residence at 2810 Alhambra Drive to the south, vacant parcels to the west of Monte Cresta Drive, and Monte Cresta Drive and the residence at 2828 Monte Cresta Drive to the north. (See Figure 1). The project site is currently undeveloped and contains vegetation and wildlife habitats consisting primarily of non-native annual grassland and coast live oak woodland. The site has relatively steep slopes with an average slope of 48.7%.

Figure 1 – Vicinity Map
Table 1: Entitlement Requests
Entitlement Reason for Entitlement
Design Review Single-Family Development
Hillside Road Improvement Plan
Floor Area Transfer
Conditional Use Permit
Grading Permit
Tree Permit
Exception to Parking Lanes under BCC Section; 7-13(e)(7)(a-c) Exception to Cul-de-sacs under BCC Section; 7-13(4)(i)
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RECOMMENDATION
Staff recommends that the Planning Commission adopt the attached resolution recommending the Single-Family Design Review, Hillside Road Improvement Plan, Floor Area Transfer, Conditional Use Permit, Grading Permit, Tree Removal Permit, and City Code Exceptions subject to City Council approval.1

APPLICATION HISTORY
• The Kraft application was submitted to the City in November 2015 and was deemed incomplete in December 2015.
• In February - December 2016, the application was submitted and resubmitted to the City four times; each submittal was deemed incomplete.
• In December 2016, the applicant appealed staff’s determination that his project was incomplete to the Planning Commission, who in January 2017, also found the application to be incomplete.
• In January 2017, the applicant appealed the Planning Commission determination to the City Council in which the City Council also found the application to be incomplete. • In March 2017, the applicant submitted a Roadway Improvement Plan as required to complete his application. In April 2017, the application was deemed incomplete. • In June 2017, the application was resubmitted to the City and in July 2017 the application was deemed incomplete.
• In August 2017, the application was resubmitted to the City and in September 2017 the application was deemed complete with comments.
• In January 2018, plans were resubmitted to the City to address comments, and in February 2018 the project was deemed not in compliance with the Zoning Code and Public Works drainage standards.
• In May 2018, plans were resubmitted to the City to address comments; in June 2018 the project was deemed not in compliance with the Zoning Code and Public Works drainage standards. • In August 2018, plans were resubmitted to the City to address comments; in September 2018, the project was deemed not in compliance with the Public Works drainage standards. • In October 2018, the applicant resubmitted plans with three different conceptual storm drain designs. In December 2018, staff sent comments to the applicant indicating that his engineer would need to choose a design that conforms to the City’s design standards and adequately address Public Works comments.
• In May 2019, plans were resubmitted to the City; in June 2019, staff determined additional analysis was needed to support the proposed drainage plan. • In June 2019, the Zoning Administrator denied the floor area transfer application in part due to insufficient information pertaining to the ownership of a transfer lot that went unresolved. 1 Please note: This recommendation is made in advance of public testimony or Commission discussion of the project. At the public hearing, these two factors, in conjunction with the staff analysis, will be considered by the Commission in rendering a decision on the project.
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• In August 2019, additional analysis to support the proposed drainage plan was submitted to the City; in August 2019, staff provided additional comments. • In October 2019, the applicant resubmitted plans with a different conceptual storm drain design to the City; in November 2019, staff provided additional comments. • In January 2020, the Planning Commission considered action to deny the Single-Family Design Review (SFDR) request. The Planning Commission granted a continuance of the Single-SFDR application with the condition that the applicant submits floor area transfer and certificate of compliance applications within thirty days of the Planning Commission meeting. • On February 10, 2020, the applicant submitted floor area transfer and certificate of compliance applications.
• August 2021-February 2022 - plans and additional analysis to support the proposed drainage plan was submitted to the City four times; staff provided comments with each submittal. • In March 2022, staff completed their review with no further comments.

PRIOR ACTIONS
In 2020 the applicant applied for a Certificate of Compliance (“COC”) for the subject property and a parcel which would potentially be a candidate for the floor area transfer. In 2021 the applicant also applied for a COC for another parcel which would also potentially be a candidate for the floor area transfer. After reviewing the applications, the Community Development Director, in consultation with the City Attorney, determined that a Conditional Certificate of Compliance (“CCOC”) was warranted.

A CCOC is issued when it has been determined that a property does not comply with the State of California’s Subdivision Map Act (“SMA”) and includes a list of conditions that must be satisfied in order to bring the property into compliance with the SMA. The CCOC’s were issued and subsequently recorded with the County of San Mateo later in 2021 and 2022. Further discussion of the CCOC follows in the staff report. The Notice of Final Determination provides background information and context related to the issuance of the CCOC (see Attachment 12). According to City records, there have been no other Planning actions for these parcels.

GENERAL PLAN AND ZONING CODE DESIGNATIONS
The project site is located in a hillside residential area of the San Juan Hills area of Belmont. Lands to the north and west of the roadway extension are primarily undeveloped residentially designated parcels zoned HRO-2. The paved portion of Monte Cresta Drive to the east of the project site has been developed with hillside residences and the area is zoned R-1/B. The General Plan identifies the previously developed residential properties to the east of the road extension as Low-Density Residential (RL).

According to Section 4.7 of the City of Belmont Zoning Code, one-family residences are permitted in the HRO-2 District. The Belmont General Plan identifies the land use on the subject property as Hillside Residential and Open Space (HROS). The property is located within the San Juan Hills Specific Plan Area. According to the General Plan, low-density residential development in the San Juan Hills area is appropriate only when it has been demonstrated that safe development can take 322

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place consistent with the policies of the General Plan and that adequate access, utilities, fire services and other essential services are available.

PROJECT PROPOSAL
Floor Area Transfer
The proposed project includes a Floor Area Transfer as described in the San Juan Hills Area Plan.

Floor Area Transfers are permitted to allow development to occur on “receiving sites” while preserving open space on “sending sites”. Pursuant to Belmont Zoning Ordnance Section 4.7.11(d), non-contiguous parcels within the HRO-2 Zoning District are permitted a permanent transfer of floor area (1,200 sq. ft.) from one parcel to another. A conservation easement is required to be recorded over the entire sending property. As a part of this project, the applicant proposes to transfer floor area from two non-contiguous parcels along the unimproved portion of Monte Cresta Drive (APN 043- 242-210 Lot 19 & APN 043-165-090 Lot 43). The parcels are located approximately 470 feet northwest (Lot 43) and approximately 590 feet north (Lot 19) of the existing terminus of Monte Cresta Drive.

Development Potential
BZO Section 4.7.11.(c) Substandard Lots states, “Vacant lots which are nonconforming to the required lot size shall be allowed a floor area which is the larger of 1,200 sq. ft. or the floor area ratio applicable to the lot's slope category, except when the average lot slope exceeds 30%, then the allowed floor area shall be the larger of the minimum floor area or the floor area ratio applicable to the lot’s slope category as shown on Table 2 – HRO-2 Floor Area Ratio Standards.” Based on the ordinance section above, and the HRO-2 Floor Area Ratio Standards Table, the subject building site at 49% slope is allowed 900 sq. ft. of floor area. As mentioned earlier, the applicant proposes to transfer floor area from two non-contiguous parcels along the unimproved portion of Monte Cresta Drive allowing the permanent transfer of 2,400 square feet of floor area to the building site. Thus, the site would be allowed a maximum of 3,300 sq. ft. of floor area.

Single Family Dwelling
The project applicant proposes to construct a 3,299 sq. ft. multi-level residence with an attached garage with a driveway extending from the terminus of Monte Cresta Drive. The residence would contain an ADA-compliant elevator, connecting the upper and main levels of the building. (See Table 3 - Dwelling Floor Area Summary for more details).
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Table 3 – Floor Area Summary
Proposed Floors Type of Rooms
Upper Floor (Street Level) – 822 Sq. Ft. Entry / living area, stairs, elevator, and two-car garage.

Main Level – 1,445 Sq. Ft. Great room, kitchen, pantry, two bedrooms, two and a half bathrooms, stairs, and elevator.

Basement – 1,032 Sq. Ft. Three bedrooms, two bathrooms, laundry area, stairs, and elevator.

Total = Sq. Ft. 3,299
The upper level of the proposed residence would be constructed roughly at grade with Monte Cresta Drive. The main level of the residence would extend downslope from the upper level of the dwelling.

The building façade would have a combination of vertical wood siding, stucco finish, metallic cladding, stone cladding, and two-sided metallic cladding and horizontal wood siding. The façade of the building would be articulated with recessed windows, parapets, exposed hollow structural section columns, and wall extensions. Glass guardrails would enclose the driveway and walkway and surround the upper, mid, and lower decks that would be located along the south-facing façade of the building. (See Figure 2).

Space Intentionally Left Blank
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Figure 2 – Architectural Rendering
Table 4 – Project Data
Criteria Existing Proposed Required or Max.

Allowed
Lot Size 9,729 sq. ft. 9,147 sq. ft.* No Change
Slope 49% No Change No Change
FAR NA 0.360 0.360
Square Footage NA 3,299 sq. ft. 3,300 sq. ft. max. per
BZO 4.7.11(c) & (d)
Parking NA
Two-car garage
(20’ x 20’)
Two uncovered
Two-car garage
Two uncovered
*Adjusted lot size (lot area minus the dedicated right-of-way).

Project Data Table continued on pg. 8.
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Setbacks:

Front NA 18’ 3” 15’
Side (right) NA 7’ 8” 7’
Side (left) NA 7’ 2” 7’
Rear NA 50’ 9” 15’
Driveway length NA >18’ 18’
Height NA 28’ 28’
Zoning Conformance
Section 9.7.1 (g) of the Belmont Zoning Ordinance (BZO) provides as follows:
“Driveway bridges including all structural support components, walls, piers, etc., which are required to provide vehicular access to on-site parking are permitted within the required front and side yards”
The applicant is proposing a portion of a driveway bridge within the front setback in order to gain access to the site and to support the home. The project is in conformance with section 9.7.1 (g) of the BZO.

Residential Design Criteria
The applicant has incorporated the standard of Daylight Plane to mitigate perceived building bulk at the rear elevation. The project plans effectively demonstrate that the rear elevation would fall beneath the required plane. The applicant also incorporated the standard of Prescribed Articulation to moderate building massing at the front, rear and side elevations. The building elevations will feature offset walls, decks, recessed windows, and complementary exterior building materials that would distribute the architectural volume of the residence. The plans sufficiently demonstrate that the building elevations would be articulated beyond the minimum required amount. As such, the project is in compliance with the City’s Residential Design Criteria standards.

Residential Design Guidelines
The applicant has made significant efforts to ensure the proposed dwelling would be substantially compliant with the Residential Design Guidelines. The project would maintain a consistent architectural theme and avoid mixing features of different styles, as dictated by Guideline A-1. In accordance with Guideline B-1, the project avoids flat two-story building walls and includes varying rooflines. Furthermore, the proposed design effectively minimizes the requisite grading by conforming to the natural slope of the property, thus maintaining consistency with Guideline B-3. As such, the proposal is substantially compliant with the Residential Design Guidelines.

Grading
Grading estimates have been provided on Sheet C-0 of the project plans (Title Sheet). Estimated earthwork quantities for the project include 150 cubic yards (CY) of cut and 650 CY of fill (500 CY fill-import).
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Tree Removal
The project proposes the removal of one of the four onsite trees. The tree to be removed is a Coast live oak in poor condition that is recommended for removal. The remaining three onsite trees, all Coast live oak trees, and two Coast live oak trees located on a neighboring property whose canopies extend onto the project site, would be protected during project construction through implementation of a tree protection plan.

Landscaping & Site Improvements
Site landscaping improvements would include a paved driveway and walkway off Monte Cresta Drive, an uncovered deck off the south end of the new residence, retaining walls, and various plantings. The new driveway and walkway would consist of a concrete deck on structural steel with recessed artificial turf decorative inserts. New plantings would consist of 21 trees, all California native tree species, and a mix of California native and non-native shrubs and groundcover. All new plantings would be low water use vegetation. The landscape plantings would be established consistent with Cal Fire Defensible Space requirements for the HFHSZ.

The project proposes to construct a retaining wall off site and in the public road right-of-way along the curve of the cul-de-sac that would serve as the terminus of the proposed road extension. This retaining wall would extend on site to span underneath and support the proposed on-site driveway bridge. Additional retaining walls would be constructed along both sides of the proposed residence to stabilize and support the disturbed slope. Retaining walls have been designed according to the specifications set forth in geotechnical investigations and reports prepared for the proposed project.

Utilities
The project site currently does not contain any utilities infrastructure. The project proposal includes the installation of new water, sanitary sewer, electricity, and storm drain utilities.

Water Supply
The proposed residence would receive water from the Mid-Peninsula Water District. The project would install a water supply lateral that would connect to an existing water main in Monte Cresta Drive. The project would also relocate an existing fire hydrant on Monte Cresta Drive as part of the proposed road extension.

Sanitary Sewer
The proposed residence would receive sanitary sewer collection service from the City of Belmont.

Wastewater collected from the residence would be conveyed via the City of Belmont’s sanitary sewer system and treated at the Silicon Valley Clean Water wastewater treatment plant in Redwood City.

The project would install a 6-inch sewer lateral and sewer manhole that would connect to an existing sewer main in Monte Cresta Drive.
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Electricity
The proposed residence would receive electricity services from Pacific Gas & Electric Company (PG&E). The project would install a new electrical line that would connect to an existing PG&E vault and power infrastructure on Monte Cresta Drive.

Stormwater Drainage
The project would install stormwater capture and treatment features onsite, including storm drain lines, a trench drain, and a separate sub-drain system consisting of retaining wall subdrains, a sump pit and pump, and a force main that would connect to a curb-thru drain on Monte Cresta Drive.

Stormwater collected onsite would be collected via the storm drain downspouts and lines, directed to the sump pit, and conveyed via the force main into the City’s stormwater collection system on Monte Cresta Drive. Stormwater runoff from the road extension will be conveyed to the existing gutter along the northeast section of Monte Cresta Drive and divert the stormwater to the nearest existing catch basins located at Barclay & Monte Cresta Drive.

Roadway Improvement Plan
Background
The property included in the application is located within the San Juan Hills. The lotting and road pattern in the area generally follows subdivision maps filed in 1926 and 1927 before the modern Subdivision Map Act that gave local jurisdictions authority to require improvement of roads as part of the subdivision approval process. As a result, many lots in those early subdivisions are served by “paper roads” that have never been built. The subject property is sited just beyond the improved portion of Monte Cresta Drive, one of the original “paper roads.” The lot is accessible only from the unimproved portion of the road right of way.

The San Juan Hills Area Plan (SJHAP) was adopted by the City in 1988 to deal with the problems posed by the antiquated subdivision of the San Juan Hills. Chief among those problems are steep slopes and potential geologic instability at locations where roads were laid out on the subdivision maps but were never improved. A survey of these areas of geologic instability was prepared and incorporated in the Area Plan (Figure 4 – SJHAP Geologic Hazard Policy Map) and adopted by City Code Section 7-12(d). The Area Plan also adopted policies for the development of roads in areas of geologic instability shown on the Geologic Hazard Policy Map to ensure safe development. In particular, Natural Conditions Policy 5 and Infrastructure Road Policy 8 require appropriate mitigation of moderate geologic hazards affecting road development. Moderate geologic hazards are defined by the policies to include areas categorized on Figure 4 (and shown in City Code Section 7- 12(d)) as “PDF” (potential debris flow movement2
), which is the category of hazard affecting the
proposed road segment.
2 "Pdf" is defined as "steep to very steep terrain mantled with a thick cover of soil, colluvium, and landslide debris... susceptible to rapid downslope movement in the form of debris flows or earth flows". 328

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To facilitate these policies, Infrastructure Road Policy 10 requires an application for a home within the San Juan Hills that is not located on an improved road be accompanied by a road improvement plan for either the entire unimproved road through to an existing improved road, or for an unimproved road segment only. A road segment plan extends from the end of an existing improved road to the point where extending the road would become infeasible due to physical constraints. Policy 10 states that examples of such constraints are “extremely steep slopes and areas categorized on Figure 4 as moving deep landslides (Md).”
City Code Section 7-13(e) implements Infrastructure Policy 10 by establishing application requirements and findings for approval of a through road or road segment. A road segment plan may be approved when, among other findings, it can be demonstrated that a stable, safe, through road cannot be reasonably constructed because of physical constraints. (City Code Section 7-13(e)(10)h.1.) One of the application submittal requirements for a road segment plan is “a report signed by a licensed geotechnical engineer concluding that the physical constraints are such that a stable road cannot be reasonably constructed through to a paved road. The report must describe the specific constraints precluding a through road and evaluate the impacts and costs of methods of overcoming the constraints through removal or engineering solutions.” (City Code Section 7-13(e)(9)b.1.).

Feasibility of a Through Road
To show infeasibility, City Code Section 7-13(e)(9)(b)(1) requires a report signed by a licensed geotechnical engineer containing certain facts and findings. To meet this standard, the applicant has submitted a feasibility report from 2008 from a previous road improvement project (see Attachment 5). Although the 2008 feasibility report was reviewed by the City’s geologic and geotechnical consultant and concluded that they were in fundamental agreement with the basic findings of the report, the application for the road improvement plan was ultimately not pursued, no decision was ever made, and the City made no final decision on the adequacy of the submitted report. Thus, City staff requested that the report be updated.

In a 2017 appeal decision (upholding the decision of the Planning Department that the Application is incomplete), the Planning Commission in their review asked that the requirements regarding the feasibility report be met in the manner least burdensome to the applicant. To provide more direction to the applicant, the City’s geologic and geotechnical consultant reviewed its earlier recommendations and required that the project geotechnical consultant to make observations and inspect the entire length of the unimproved section of Monte Cresta Drive and make recommendations and perform additional testing and borings, if needed. The project geotechnical consultant was also required to update any conclusions and recommendations regarding the feasibility of the through roadway. The City’s geologic and geotechnical consultant’s recommendations was included with a list of requirements that had to be submitted to the Planning Department to complete the application as a part of a 2017 City Council Resolution (upholding the Planning Commission’s decision that the project application was incomplete).

In February 2017, the project geotechnical consultant (Romig Engineers) walked the entire unimproved roadway section between the existing improved and paved ends of Monte Cresta Drive to observe current conditions. The results of this site investigation determined that the site conditions 329

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have not changed significantly since the 2008 feasibility study that was prepared. Based on the project geotechnical engineer’s site investigation, they concluded that constructing a through road remains impractical and economically infeasible. The results of this site investigation are further detailed in Romig Engineers’ Geologic and Geotechnical Update Letter, dated February 23, 2017 (see Attachment 8).

The geotechnical information that was submitted for the project was peer reviewed by the City’s geologic and geotechnical consultant Cotton, Shires, and Associates (CSA). CSA concurred with the project geotechnical consultant that the through road remains impractical and economically very costly because of very significant landslide constraints (Cotton, Shires and Associates Peer Review Letter, October 26, 2017 – see Attachment 9).

Roadway Segment Plan
The proposed road plan would be for a segment of roadway that will serve as access to the property.

The applicable section of the Belmont City Code to this roadway improvement plan, Section 7- 13(e)(9)(b), states that a plan for an unimproved road segment may be approved, instead of a plan for the entire roadway, when the segment lies between an existing paved road and an area where physical constraints, such as very steep slopes or geologic instability effectively preclude construction of a through connection (such as areas mapped or designated Md or Pdf on the current geologic hazards map). The roadway alignment west of the project site is mapped as "PDf" indicating potential debris flow movement which is the category of hazard affecting the proposed road segment. (See Figure 3).

According to the applicant’s geotechnical engineer (Romig Engineers), with confirmation by the City’s consulting geotechnical engineer (CSA) through peer review, the proposed road segment is feasible with proper design and construction. Recommended construction measures for the proposed road segment / fire truck turnaround is summarized in the Romig Engineers’ 2016 design-level geotechnical report for the residence (see Attachment 7).

Road Access
The road extension would provide driveway access to the proposed development site, and potentially provide access to the adjacent vacant lot zoned HRO-2 (Hillside Residential and Open Space) west of the new road terminus. However, this lot is not proposed for development. In addition, this lot may not be feasible for development because of the mapped potential debris flow (PDf) and landslide movement (Pd3
) on the lot.
3 "Pd" is defined as "relatively unstable landslide debris, commonly more than 10 feet in thickness on moderately steep to very steep slopes ... susceptible to renewed deep landslide movement". 330

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Figure 3 – San Juan Canyon Ground Movement Potential Map Width Standards for Hillside Roads
The project proposes to extend Monte Cresta Drive approximately 50 feet to the west from its current paved terminus with the construction of a cul-de-sac / vehicle turnaround. The adjacent rightof-way fronting the site is considered an unimproved roadway section of Monte Cresta Drive.

Belmont City Code (BCC) Section 7-13(e)(9) provides that a road improvement plan is required to be approved by the City Council to “…ensure adequate emergency access, public safety and drainage improvements.”
Per BCC section 7-13(e)(5) Table 1, hillside roads are required to include two traffic lanes and gutters, curbs, parking lanes, and sidewalks on both sides of the road. Per BCC 7-13(e)(6), the width of a proposed hillside road or road segment may be reduced by eliminating sidewalks and/or parking lanes depending on the related cross slopes as described in BCC 7-13(e)(6) and shown in Table 2 below. The project engineer has prepared a cross slope analysis that indicates an average slope of 29% (see Attachment 10). Per Section 7-13(e)(6) and Table 2 - Hillside Road Width Related to Cross Slopes, the roadway shall be 40 feet in width, including two 10-foot-wide travel lanes, two 5.5-footwide parking lanes, two two-foot-wide curb and gutters and one five-foot wide sidewalk. However, per San Mateo Consolidated Fire Department (SMCFD) comments, parking within the turnaround should be designated as “No Parking” and “rolled red curb” to provide for adequate emergency access. The practical layout for the proposed turnaround includes 20-foot travel lanes, two two-foot curb and gutters, and one five-foot sidewalk along the southern side of the turnaround. The applicant has requested an exception to install parking lanes. The exception is discussed further in this report. 331

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Table 2 - Hillside Road Width Related to Cross Slopes
Cross
Slope
Traffic
Lanes
Curbs &
Gutters
Parking
Lanes Sidewalk TotalWidth
21% - 30% 20' 2' both sides
*5.5' both
sides
5’ one
side 29’
*Per the SMCFD the turnaround should be designated as “No Parking” and “rolled red curb” Standards for Hillside Roads
The standards for an unimproved road segment terminating in a cul-de-sac are set forth in Belmont City Code Section (BCC) 7-13(4)(i). In general, the length of a cul-de-sac may not be longer than 800 feet (from the turnaround to the open street) with a turn-around radius of 32 feet, unless the city engineer in consultation with the fire chief recommend a longer cul-de-sac or smaller turnaround based an analysis of several factors.

The existing terminus of Monte Cresta Drive is a cul-de-sac4 with a bulb design turnaround5. The existing cul-de-sac is approximately 820 ft. long that extends from the existing turnaround to the open street at the intersection of Barclay Way and Monte Cresta Drive, and currently serves 17 homes along the 2800 block of Monte Cresta Drive (See Figure 4).

Since the current terminus of Monte Cresta Drive does not have adequate space for fire truck turnaround, the proposed project includes construction of a fire truck turnaround within the Monte Cresta Drive right-of-way. A portion of the subject lot frontage will be dedicated right-of-way to accommodate the construction of the turnaround.

Space Intentionally Left Blank
4 Belmont City Code Definition Sec. 7-13 (e)(3)(b) Cul-de-sac is a street open at only one end with a turnaround at the other.
5 Belmont City Code Definition Sec. 7-13 (e)(3)(k) Turnaround is a space in a public right-of-way or a private road large enough to permit the turning around of a large vehicle, particularly a firetruck. It may take various configurations, including, for example, a circle, bulb, or hammerhead.
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Figure 4 – Monte Cresta Drive Cul-de-sac
The project proposes to extend Monte Cresta Drive approximately 50 feet to the west from its current paved terminus with the construction of a vehicle turnaround / cul-de-sac. The project would extend the length of the existing cul-de-sac by 50 feet to approximately 870 ft. with a turnaround radius of 29.5 feet at the end. Although the project would not meet the general specifications for a cul-de-sac, the city engineer in consultation with the fire chief evaluated the following factors in Section 7-13(4)(i):

1. Availability of a through connection via an emergency road.

Based on the geotechnical feasibility study prepared by the project engineer (Romig Engineers Inc.) and peer reviews by the City’s consulting geotechnical engineer, a throughroad extension is infeasible due to geotechnical issues and environmental conditions. The project proposes a road segment with a fire truck turnaround.

2. Number of lots/houses/occupants to be served by the cul-de-sac.

The existing cul-de-sac at the terminus of Monte Cresta Drive currently serves 17 homes along the 2800 block of Monte Cresta Drive. The road extension would provide driveway access to the proposed development site, and potentially provide access to the adjacent lot west of the new road terminus.
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3. Type of construction of buildings (e.g., fire-retardant roofs and siding, interior sprinklers).

Construction for the proposed dwelling will be conditioned to meet Chapter 7A (Materials and Construction Methods for Exterior Wildfire Exposure) of the California Building Code and that the home construction includes an automatic fire sprinkler system.

4. Water pressure and availability of a secondary water main.

The project site is in a residential neighborhood surrounded by existing single-family homes with existing water service. The project would install a water supply lateral that would connect to an existing water main in Monte Cresta Drive. Water pressure for the newly installed water lines will be tested during construction of the proposed single-family home.

5. Proximity to fire station and hydrant.

Fire Station #15 is located approximately 0.8 miles from the project site and a fire hydrant is proposed at the turn-around / cul-de-sac.

6. Street width.

The project will meet the hillside road width standards related to the cross slopes with the granted exception to eliminate parking lanes.

The San Mateo Consolidated Fire Department (SMCFD) and Public Works Department (PWD) has reviewed the proposed turnaround design and determined that the length and turnaround design is appropriate with the stipulation that the turnaround includes “No Parking” and “red curb” to provide for adequate emergency access (see SMCFD and PWD Recommendation Letters - Attachment 14).

Maintenance
The road extension is considered a public right-of-way and would not be a private drive. The adjoining property owners with road frontage will have reciprocal obligation to maintain the improved road under Civil Code section 845 until such time as the city council formally accepts the road into the city street system consistent with Streets and Highways Code section 1806.

PROJECT ANALYSIS
General Plan
The project site is zoned HRO-2 (Hillside Residential Open Space - subdivided) with a General Plan Designation of HROS – Hillside Residential Open Space. The HROS land use designation allows for the construction of a single-family residence and accessory structures. The project’s proposed singlefamily dwelling and attached garage is consistent with the allowed uses of the HROS land use designation. Thus, the project is consistent with the applicable general plan designation and all applicable general plan policies as well as with applicable zoning designation and regulations. The project’s consistency with applicable General Plan policies is demonstrated in the Categorical 334

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Exemption Evaluation (see Attachment 15, Table-3 titled Project Consistency with Applicable General Plan Policies).

San Juan Hills Area Plan
The San Juan Hills Area Plan establishes policies specific to activities and development occurring in the San Juan Hills Area in which the project site is located. The San Juan Hills Area Plan is a part of the Belmont General Plan. The project’s consistency with applicable San Juan Hills Area Plan policies is demonstrated in the Categorical Exemption Evaluation (see Attachment 15, Table-4 titled Project Consistency with Applicable San Juan Hills Area Plan Policies).

Single-Family Design Review
The applicant proposes to construct a new 3,299 square foot dwelling. Under Table 13A.4 (a) (Residential Design Review (RDR) Authority Thresholds) of the BZO, new single-family homes is a Tier-3 project requiring Residential Design Review. Residential Design Criteria are also be applied in conjunction with the Single-Family Design Review process. The requisite Single-Family Design Review findings (BZO Section 13A.5 A-F) are provided in the attached resolution (Attachment 2).

Adoption of a Road Improvement Plan
The City requires an approved road improvement plan prior to granting a building permit for a new structure or enlargement of an existing structure on property accessible only from an unimproved road. As previously discussed, the applicant proposes to construct a new residence on property accessible only from an unimproved road. The proposed road plan would include a road segment extending Monte Cresta Drive with a turn-around / cul-de-sac.

To adopt a hillside road improvement plan, the Planning Commission must make a recommendation to the City Council regarding each of the following findings:
a. The road improvement plan is consistent with the purposes and policies of the San Juan Hills Area Plan; and,
b. The proposed project provides for safe vehicular and pedestrian movement; and, c. The road has been designed to minimize grading and vegetation removal to the extent feasible; and,
d. Drainage, erosion control and slope stability have been fully addressed in the design of the road improvements; and,
e. The applicants have demonstrated that adequate financing is available to construct and maintain the road as proposed; and,
f. Access to abutting properties has been adequately considered in the design of the road improvements; and,
g. If the project is for a cul-de-sac, the length and turnaround design are appropriate and consistent with emergency access requirements; and
h. If the plan is for an unimproved road segment, the City Council must have made all of the above findings in the affirmative, plus:

1. A stable, safe, through road cannot be reasonably constructed because of physical constraints; and,
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2. Recommendations for access to properties abutting the part of the road which would not be improved under the plan are reasonable and consistent with the purposes and policies of the San Juan Hills Area Plan.

The requisite Hillside Road Improvement Plan findings are provided in the attached resolution (Attachment 2).

Floor Area Transfer
As previously discussed, the project proposes to transfer floor area from two non-contiguous parcels along the unimproved portion of Monte Cresta Drive. Under certain circumstances described in the following findings, the HRO-2 District encourages the permanent transfer of floor area development potential in the HRO-2 Zoning District from one site to a non-contiguous site with approval of a Conditional Use Permit by the approval authority. All findings as indicated in BZO Section 4.7.11 (d)(3)(a-f) (see below) of the City of Belmont Zoning Code are required to be made in the affirmative prior to approval.

Conditional Use Permit (CUP) Findings required for approval of a Floor Area Transfer are as follows:
a. The proposed transfer of density is consistent with the policies of the San Juan Hills Area Plan and the Geologic Hazards Ordinance.
b. Adequate infrastructure exists or its construction is assured, and for sites requiring road improvement plans, such plans have been approved.
c. The pattern of development which would result from the transfer of floor area is better than could be achieved through the application of this ordinance without floor area transfer, due to less grading, less street and utility extension, and better building site locations. d. The sending property will be protected from development by the establishment of a conservation easement over its entirety or be merged with an adjacent lot and a conservation easement established over land equal in area to the sending site, and the ownership and management of such property will be adequately provided for. e. The proposed building sites will not be in an area designated Md or Pdf on the current geologic hazards map.
f. All floor area transfer standards will be met
The requisite CUP findings for a Floor Area Transfer are provided in the attached resolution (Attachment 2).

Conditional Certificate of Compliance (CCOC)
As referenced in the Prior Actions section of this report, a CCOC was issued and recorded for the subject property in 2021. The CCOC provides a list of conditions that must be satisfied before issuance of a permit or other grant of approval for development. Satisfaction of these conditions will bring the property into compliance with the Subdivision Map Act and the local subdivision ordinance. 336

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Conditional Use Permit (CUP)
Belmont Zoning Code (BZO) Section 4.7.9 sets forth general residential density and minimum lot size requirements which are based on the average lot slope. A condition identified in the CCOC was that the subject property must comply with all relevant Subdivision Ordinance and Zoning Ordinance standards for lot size, dimensions, and standards at the time the property owner acquired the property (October 21, 2015). As described in Table 5 below, the property does not satisfy the requisite minimum lot area. However, given the existing layout of the property and the fact that all surrounding properties are controlled by separate entities, and the surrounding adjacent properties to the east and south are within a different zoning district (R1-B) the property owner has a limited capacity to satisfy the requisite minimum lot area.

As part of their effort to bring the property into compliance with subdivision requirements, the applicant has applied for a Conditional Use Permit requesting a smaller lot size pursuant to BZO Section 4.7.96
.

Table 5 – HRO Zoning Ordinance Density & Lot Size Standards Development Criteria Minimum Required Proposed
Lot Size (sq. ft.) 403,333 sq. ft.* 9,137 sq. ft**
Avg. Lot Width 60 ft. Approx. 77 ft.**
Frontage 40 ft. Approx. 64 ft.**
*Based on the BZO Sec. 4.7.9 Table 1 (HRO Density and Minimum Lot Size Standards), the subject site at 49% slope is required a minimum lot size of 403,333 sq. ft.
** Adjusted lot size and lot dimension after right-of-way dedication.

The Planning Commission’s determination will be forwarded as recommendations to the City Council, in accordance with Section 10.5.1 of the Belmont Zoning Ordinance. Should the Council decide to approve the application, approval would be conditioned on prior satisfaction of all other conditions outlined in the CCOC. All findings as indicated in BZO Section 10.7.3 (see below) of the City of Belmont Zoning Code are required to be made in the affirmative prior to approval.

Conditional Use Permit (CUP) Findings:
(1) The location of the proposed use is compatible to other land uses in the general neighborhood area and does not place an undue burden on existing transportation, utilities and service facilities in the vicinity.
(2) The site is of sufficient size to accommodate the proposed use together with all yards, open spaces, walls and fences, parking and loading facilities, landscaping and such other provisions required by this Ordinance.
6 BZO Sec. 4.7.9 General Residential Density and Lot Size Standards, in part states, “The maximum allowed residential dwelling unit densities and minimum lot sizes in the HRO districts shall be computed in accordance with the applicable provisions of the Slope Density Table in this Section unless a conditional use permit authorizing a smaller lot size is approved pursuant to provisions in the respective HRO Zone.” 337

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(3) The site will be served by streets of capacity sufficient to carry the traffic generated by the proposed use.
(4) The proposed use, if it complies with all conditions upon which approval is made contingent, will not adversely affect other property in the vicinity or the general welfare of the City.

The requisite CUP findings are provided in the attached resolution (Attachment 2).

Groundwork and Geotechnical Recommendations
The City of Belmont’s Ground Movement Potential and Geologic Hazard Policy Map and Table 6 (Geologic Hazard Criteria for Development) of the San Juan Hills Area Plan lists all of the proposed road segment and the majority of the proposed residence within the "Ps" designation indicating the potential for creep or shallow landsliding. The southeastern portion of the property is mapped as "Pfs" indicating the presence of fill materials that maybe susceptible to instability. However, the site design does not include project components (residence, walls, and drainage improvements) of the “Pfs” area of the site.

The City of Belmont’s standard process in this development scenario includes the submittal of an engineering geotechnical investigation and peer review by the City’s consulting geotechnical engineer, prior to approval of the project. The investigation is required to evaluate the natural slope conditions of the property and provide recommendations for mitigating and/or correcting any unstable conditions that will assure the safety of the proposed development.

The applicant has submitted a feasibility evaluation dated 12/3/15, Geotechnical Investigation dated 1/26/16, and letters dated 8/2/16, 10/7/16, 6/12/18, 2/23/17 and 5/29/19 prepared by Romig Engineers, Inc. Copies of the reports and letters are included as Attachments 6 - 8. The reports and letters were peer-reviewed by the City’s consulting geotechnical engineer in letters dated 12/10/15, 3/2/16, 11/14/16, 1/11/17, 10/26/17, 7/10/18, 12/23/21, and 3/22/22. Copies of the letters are included in Attachment 9. The City’s consulting geotechnical engineer’s recommendations for plan review and construction inspections are included in the conditions of the project approval (see Attachment 3).

The geotechnical reports and letters concluded that the proposed residential development is suitable for the site from a geotechnical perspective, provided that the recommendations contained in the report are implemented in the design and construction. The City’s consulting geotechnical engineer has peer reviewed the reports and does not have feasibility objections to the layout of the proposed site improvements. The City’s consulting geotechnical engineer has also provided recommendations for geotechnical review of final building and grading plans and field inspections during construction.

All the City’s consulting geotechnical engineer’s recommendations have been included in the attached Conditions of Approval.

Grading
As previously discussed, it is anticipated that approximately 150 cubic yards (CY) of cut and 650 CY of fill material (500 CY fill-import) would be required for construction of the project. Development projects that exceed 500 cubic yards of grading require a Grading Plan or Permit approval by the approval authority. Key considerations for the Grading Plan identified in the required findings for approval (City Code Section 9-27 (a)–(h)) include review of the grading for site stability, and erosion 338

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control/flooding/water quality impacts. The grading must also be necessary for “reasonable” use of the site, which has generally been interpreted to include uses that conform to the project site’s zoning district and are constructed in accordance with established development criteria. The visual compatibility impacts of grading are assessed as well. This review entails an evaluation of the potential condition of the property as a result of the proposed grading (including tree preservation).

For example, depositing large quantities of fill and clearcutting trees on a project site solely to gain a view over surrounding properties, may be considered visually incompatible grading (it also may be considered unnecessary).

Conformance with the technical aspects of grading (site stability, erosion control, dust control, and the methods of cut, fill, compaction, etc.) are reviewed by engineers in the Public Works Department and consultants working for the City. The grading plan has been reviewed by the Public Works Department and found not to be excessive, as there is no grading unnecessary for the project (i.e., construction of building foundation, road improvements, retaining walls and installation of landscaping, frontage improvements, and storm water control measures). The project grading would be visually compatible with the surrounding area, as it entails the construction of a single-family residential building on a down sloping lot, surrounded by similar development.

A final grading plan will be reviewed and approved by the Public Works Department, prior to building permit issuance. The City’s consulting geotechnical engineer has provided several recommendations that have been included in the conditions of approval.

Unless an exception is granted, grading is limited to the drier season (April 15- November 14), which also serves to prevent erosion; however, the Department of Public Works will require the applicant to adhere to specific best management practices (BMPs) to avoid air and water quality impacts. In addition, City standard conditions would require the applicant to address potential noise, vibration, cultural, and hazardous materials impacts, prior to and during grading operations.

To prevent traffic impacts, the applicant will be required to submit a construction management plan for review and approval by the Department of Public Works. A primary consideration of this plan would be to ensure that project construction does not adversely impact traffic operations within the surrounding neighborhoods.

The City's Building Division and Public Works Department have reviewed the grading plans for the project and have determined that the plan is in conformity with the Building Code and the City of Belmont Grading Ordinance (Chapter 9 of the City Code). Based on the foregoing discussion, staff recommends that the findings for approval of the Grading Permit can be made in the affirmative.

Tree Removal & Replacement
The project proposes the removal of one of the four onsite trees. The tree to be removed is a Coast live oak in fair condition that is recommended for removal. The project applicant submitted an arborist report (Kielty Arborist Services LLC, 1/24/16, and updated on 7/24/18) evaluating the potential impacts of project construction on trees (see Attachment 12). The arborist report and the plans submitted as part of the project indicate that the tree proposed for removal is directly impacted by the project construction. The applicant proposes to plant two preferred species Coast live oak 339

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(Quercus agrifolia) trees as part of the project in conformance with Section 25-10 (a) of the City Code. In determining whether to approve a Tree Removal Permit, decision makers must balance established criteria supporting removal of protected trees against criteria supporting retention.

These criteria are provided in the attached resolution (Attachment 2).

Criteria Supporting Removals & Retention
The project includes the removal of one protected tree. The arborist report and plans submitted as part of the project indicate that the tree proposed for removal is directly impacted by project construction (criteria for removal). Based upon review of the arborist report, and the site and grading plans, staff recommends that the proposed tree removal is necessary for the construction of the project. Based on the foregoing, staff recommends that the Planning Commission adopt the attached resolution recommending City Council approval of the Tree Removal Permit.

The applicant is requesting an exception to the Road Standards to eliminate parking lanes. Pursuant to BCC 7-13(e)(7)(a-c), exceptions to any of the hillside road standards may be granted by the administrative or legislative body approving the road improvement project upon recommendation of the city engineer based on consultation with the fire chief and appropriate engineering evaluations. Staff proposes that the Planning Commission recommend that the City Council make the following findings for the exception:
a. Granting the exception will not unduly impair vehicular or pedestrian safety, or emergency access.
b. Granting the exception will result in a road improvement which is consistent with the San Juan Hills Area Plan and other city ordinances.
c. Reducing the standard is necessary to avoid excessive grading or vegetation removal or to reduce the risk of erosion, flooding or slope failure.

The requisite findings for the exception are provided in the attached resolution (Attachment 2).

ENVIRONMENTAL CLEARANCE (CEQA)
Applicability of CEQA Categorical Exemption
Based on the site plans, information provided by the project applicant, and documentation of potential environmental impacts resulting from the proposed project, the project is eligible for a categorical exemption under CEQA Guidelines Section 15303 (a), (d) and (e), New Construction or Conversion of Small Structures, and Section 15332, In-Fill Development Projects (see Attachment 15 - Categorical Exemption Evaluation).

Class 3 Exemption – New Construction or Conversion of Small Structures Projects falling under the 15303 exemption are considered Class 3 projects. Class 3 projects consist of construction and location of limited numbers of new, small facilities or structures; installation of small new equipment and facilities in small structures; and the conversion of existing small structures from one use to another where only minor modifications are made in the exterior of the structure. The numbers of structures described in Section 15303 are the maximum allowable on any legal parcel. 340

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Of the example project types included under Section 15303, the project would qualify for types (a) and (d):
(a) One single-family residence, or a second dwelling unit in a residential zone. In urbanized areas, up to three single-family residences may be constructed or converted under this exemption.
(d) Water main, sewage, electrical, gas, and other utility extensions, including street improvements, of reasonable length to serve such construction. (e) Accessory (appurtenant) structures including garages, carports, patios, swimming pools, and fences.”
Class 3 Projects do not have specific conditions as part of their approval. The project proposal includes the construction of a single-family home, a road extension to serve said single-family home and provide adequate emergency services access to the site, and the installation of associated landscaping features, including retaining walls, and utilities extensions. The proposed project would qualify for a Class 3 exemption under items (a) and (d), as it would involve the construction of one single-family residence; associated water main, sewage, electrical, gas, and storm drain utility extensions; and street improvements (i.e., a road extension) designed to serve the residence and comply with the City’s municipal code requirements.

Class 32 Exemption – In-Fill Development Projects
Projects falling under the 15332 exemption are considered Class 32 projects. Class 32 projects are characterized as in-fill development meeting the conditions listed below:
(a) The project is consistent with the applicable general plan designation and all applicable general plan policies as well as with applicable zoning designation and regulations. (b) The proposed development occurs within city limits on a project site of no more than five acres substantially surrounded by urban uses.
(c) The project site has no value as habitat for endangered, rare, or threatened species. (d) Approval of the project would not result in any significant effects relating to traffic, noise, air quality, or water quality.
(e) The site can be adequately served by all required utilities and public services. The project would not qualify for a Class 32 exemption if it does not meet all the conditions listed above.

The project’s consistency with the Class 32 exemption requirements listed above have been assessed as described below and the project has been found eligible for a Class 32 exemption.

The project qualifies as Categorically Exempt under the California Environmental Quality Act (CEQA), Section 15332 (“In-Fill Development Projects”) because it is characterized as an in-fill development which is consistent with the applicable General Plan and zoning designation; is on a project site that is less than five acres; contains no value as habitat for endangered, rare, or threatened species; would not result in any significant effects relating to traffic, noise, air quality, or water quality; and the site can adequately be served by all required utilities and public services.

Based on the information provided in Categorical Exemption Evaluation, the proposed project qualifies for a categorical exemption under CEQA Section 15332, In-Fill Development Projects. 341

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Cumulative Impacts
The proposed project would construct a new single-family home on a vacant parcel located in an existing neighborhood in a built-out area in the City of Belmont. Although there may be additional private development projects underway in the project vicinity and additional in-fill development may be proposed in the project vicinity in the future, remaining undeveloped land in the project vicinity and City of Belmont is limited and development of remaining undeveloped lands may be infeasible due to zoning or general plan land use designation and other constraints. Further, similar projects that may be proposed in the future would be subject to City conditions of approval and mitigation measures, if needed, to reduce potentially significant impacts. Therefore, the project would not have a significant cumulative impact.
1988 San Juan Hills Area Plan (SJHAP) Environmental Impact Report (EIR) The SJHAP EIR, adopted by the Belmont City Council on March 22, 1988, considered all potential environmental impacts under an assumed maximum buildout of 372 residences, 267 of which were anticipated to occur on vacant lots that were not served by an improved road. These lots were later designated under one of the Hillside Residential Open Space (“HRO”) zoning districts in the San Juan Hills Area, HRO-1 and HRO-2. However, development in the San Juan Hills Area has not occurred to that extent for the HRO lots, and that level of development is now highly unlikely to occur due to a variety of factors and subsequent actions by the City, including limitations on density transfers, an adopted lot merger program, geologic hazard regulations, slope density/intensity ordinances, more restrictive development standards, an Initiative prohibiting increases in density without voter approval, and the rezoning of many properties to O/S (Open Space). Therefore, there would not be cumulative impacts for the project in excess of those studied in the SJHAP EIR.

NEIGHBORHOOD OUTREACH & PUBLIC NOTICE
December 2015 - The applicant performed neighborhood outreach as detailed in the Neighborhood Outreach Strategy attached to this report (Attachment 4). The applicant reported mailing notices to all property owners within 300 feet of the site, informing residents of the project. The applicant reported holding an open house. During this time, several neighbors illustrated several project concerns relating to the size of the proposed dwelling, private views, and construction related activities.

December 2016 - The City posted and sent Public Notice for the Planning Commission appeal hearing to all property owners within 300 feet of the site.

January 2017 - The City posted and sent Public Notice for the City Council appeal hearing to all property owners within 300 feet of the site.

November 2017 - As required, the applicant sent notices to property owners abutting the unimproved portion of Monte Cresta Drive requesting their input on the proposed project. The applicant also reported holding a meeting on site. Three property owners attended the meeting. During this time, one property owner raised concerns related to geologic hazards. The applicant reported that no other comments were received (see Attachment 4).
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January 2020 - The City posted and sent Public Notice for the Planning Commission hearing to deny the Single-Family Design Review (SFDR) request to all property owners within 300 feet of the site.

Public notice for the November 21, 2023 Planning Commission hearing was provided to all property owners within 300 feet of the site, abutting the proposed road segment, and other interested parties.

CONCLUSION
Based on the foregoing analysis, staff recommends the Planning Commission take the following actions:

1. Adopt a Resolution recommending City Council approval of the Single-Family Design Review, Hillside Road Improvement Plan, Floor Area Transfer, Conditional Use Permit, Grading Permit, Tree Removal Permit, and City Code Exceptions.

ACTION ALTERNATIVES

1. Continue the matter to another date in order to address any issues that have not been resolved.

2. Recommend denial of the requested entitlements.

ATTACHMENTS

1. 300/500 Foot Radius Map

2. Resolution Recommending City Council Approval of Project Entitlements

3. Conditions of Project Approval – Exhibit A

4. Neighborhood Outreach

5. Geologic and Geotechnical Engineering Feasibility Study (June 30, 2008) & CSA Peer Review (August 13, 2008)

6. Geotechnical Feasibility Evaluation (December 3, 2015)

7. Geotechnical Investigation (January 29, 2016)

8. Geotechnical Response Letter (2016 - 2023)

9. Geotechnical Peer Review Letters (2015 - 2022)

10. Cross Slope Analysis & Exception Request (August 25, 2017)

11. Biological Assessment (October 14, 2017, and updated June 3, 2022)

12. Arborist Report (July 24, 2018)

13. Certificate of Compliance Final Determination

14. San Mateo Consolidated Fire Department (SMCFD) and Public Works Department (DPW) Recommendation and Exception Letters

15. Financial Analysis

16. Categorical Exemption (CE) Evaluation

17. 1988 San Juan Hills Area Plan EIR

18. Storm Drain Technical Memo

19. Project Plans – (Commission Only)
343

PLANNING COMMISSION STAFF REPORT
Monte Cresta Drive, PA#2015-0057
November 21, 2023
Page26
Respectfully submitted,
Rob D. Gill
Carlos de Melo
Community Development Director
CC: Applicant/Owners
Peter Brown
Director of Public Works
344

BKF No. 20166012
August 25, 2017

CITY OF BELMONT

COMMUNITY DEVELOPMENT DEPARTMENT
Attn: Rob D. Gill
One Twin Pines Lane
Belmont, CA 94002
Subject: Planning Application No. 2015-0057
(Complex Project - APN 043-165-180)
Mr. Gill:

Thank you for your time in reviewing the above-mentioned project and for providing comments related to the previous submittal package. Upon reviewing your comments for the project (Incomplete Letter – July 19, 2017) we noticed one outstanding item that we intend to clarify and address as follows:

Incomplete Item #1 (Condition 4 of Exhibit A):
“The requirements for sidewalk are stated in Section 7-13. There are no exceptions for a fire truck turnaround. Road improvements in the San Juan Hills to an unimproved road must conform to the Hillside Road Standards (e.g. sidewalk, parking lanes, etc.) in BCC Section 7-13(e) unless an exception is requested. Please specify and summarize all exceptions required to the Hillside Road Standards and submit details to justify waiving the requirements.” Per Resolution No. 2017-005, and as previously discussed during coordination meetings with City staff, we agree with the spirit of the comment. It is indeed important to understand how the proposed cul-de-sac improvements fit within the overall road improvement plan to avoid potential impacts to the properties along the unimproved road. To understand the impacts to the future overall road improvement, BKF prepared slope calculations for the overall road to determine the required street section per BCC Section 7-13.

Per BCC 7-13(e)(3)(a) Cross slope is the inclination of the ground surface across a road alignment expressed as a percent obtained by dividing vertical distance by horizontal distance. Cross slope is measured along a hundred-foot section drawn perpendicular to the contours and extending fifty (50) feet from each side of the center of the road alignment.

BKF’s slope analysis for the overall road is hereby attached as previously prepared in March 3, 2012 (Exhibit 1).

Upon analyzing 35 existing road segments, the results indicate an average slope of 41%. Per BCC 7-13(e)(6), a road with an average slope of 41%-50% would require a design to include:

Cross Slope Traffic Lanes Curbs & Gutters Parking Lanes Sidewalks Total Width 41%—50% 20' 2' both sides 5.5' one side none 29.5'
Per BKF plans, sheet C2 dated 6/20/2017 (Road Extension Conceptual Design) the following is included:
41%—50% 20' 2' both sides 5.5' one side 5’ (one side) 34.5' After further discussions via phone with Mr. Brian Dong and Mr. Gilbert Yau, we understand that the City’s interpretation on Section 7-13 requires a slope analysis for the road segment opposed to the full road. 345

Per BCC 7-13(e)(6) Cross slopes should be calculated from a detailed engineering topographic map prepared by a registered civil engineer or licensed land surveyor according to specifications required for a grading plan (section 9- 25). Our slope analysis is calculated based on the existing conditions per field observations, recent supplementary surveys, and as shown on the topographic map part of the road improvements prepared by LTI Engineers, Inc. dated September 26, 2003.

As directed by Mr. Dong and Mr. Yau, we prepared a slope analysis for the road segment (Exhibit 2) attached to this letter. The results indicate an average slope of 29%, which by BCC Section 7-13 would require:

Cross Slope Traffic Lanes Curbs & Gutters Parking Lanes Sidewalks Total Width 21%—30% 20' 2' both sides 5.5' both sides 5’ one side 40' Civil engineering plans have been revised to provide a 40’ wide road section as stated above. At the request of the Fire Department, the curbs at the turnaround shall be painted red to prohibit parking within the 5.5’ parking lane. Based on City staff’s assessment, this condition will require an exception per BCC 7- 13(e)(7). The exception requested is based on:

BCC 7-13(e)(7)(a) Granting the exception will not unduly impair vehicular or pedestrian safety, or emergency access: The Fire Department has expressed satisfaction with the proposed cul-de-sac turnaround. Pedestrian and Vehicular safety will be increased, and emergency access will be enhanced once constructed.

BCC 7-13(e)(7)(b) Granting the exception will result in road improvement which is consistent with the San Juan Hills Area Plan and other city ordinances: The exception requested will still allow the design to be consistent with the development guidelines and goals for the San Juan Hills Area Plan and other City ordinances as particularly related to the road segment and the “future road” improvements.

BCC 7-13(e)(7)(c) Reducing the standard is necessary to avoid excessive grading or vegetation removal or to reduce the risk of erosion, flooding or slope failure: BKF has reviewed several other options including a hammerhead and a standard cul-de-sac turnaround. Both alternatives require an increase in disturbance of at least 10 feet within the hillside area, which in turn would require significant grading, retaining walls, and right-ofway dedications. The additional grading, retaining walls, and right-of way dedications would make the project economically infeasible. When compared to other alternatives, due to the smaller footprint in land disturbance, the proposed turnaround decreases the amount of grading, decreases the vegetation removal, and decreases the possibility of associated slope failure.

As previously mentioned, the construction of the proposed cul-de-sac is intended for enhanced safety and for enhanced emergency service access. Such proposed emergency service access has already been deemed satisfactory by the Fire Department.

Please feel free to contact me if you need any additional information or clarification.

Respectfully,
BKF Engineers
Isaac Kontorovsky, P.E., QSD/QSP
Associate
Cc: Jeff Kraft
346
EXHIBIT 1 FULL ROAD
FULL ROAD AVERAGE SLOPE: 41 %
347
348
349
EXHIBIT 2 350
,;:.w ... COTTON, SHIRES & ASSOCIATES, INC.

CONSULTING ENGINEERS AND GEOLOGISTS
TO: Gilbert Yau
Senior Civil Engineer

CITY OF BELMONT
Department of Public Works
One Twin Pines Lane, Suite 385
Belmont, California 94002-3867
August 13, 2008
B4030C
SUBJECT: Supplemental Geotechnical Peer Review
RE: Monte Cresta Through Road
City of Belmont
At your request, we have completed a supplemental geotechnical peer review of the proposed concept for site development using:
• Geologic and Geotechnical Engineering Feasibility Study Monte Cresta Drive Through Road Belmont, California (report) prepared by Romig Engineers, Inc., dated June 30, 2008; and
• Geotechnical Investigation (report) prepared by Earth Mechanics Consulting Engineers, dated October 18, 2001.

In addition, we have reviewed pertinent technical reports and maps from our office files and completed a site reconnaissance with the Project Engineering Geologist.

DISCUSSION
The referenced report by Romig Engineers has been prepared to address the .:re"'""'"1•·· :-al t ,-, .. :1-,;la.y "f c b o-<-f-..,1,..,.;..,~ J. 1-l..rout:rh .. c·•d -i ........ O' 3" 1 �on fnot- c,v;.,1-;.,.., � .,.11-..... "'-1..i..1.LJ.\.. • ..1�U,;:,.1L,J.J.J.t. V .&.L� .. � .. Tt..L.i..LLE, \..&.L b .. ... - a ... v.&.'t, ..... .1.,-uv --· .. ��,. ...... H ....... _v easement to connect the paved portions of Monte Cresta Drive. We previously completed a geotechnical peer review of a 2001 roadway extension plan and the referenced 200.1 geotechnical report (CSA letter dated January 23, 2002). We concluded that the initial roadway extension plan and companion geotechnical report did not adequately address the site geologic slope constraints or illustrate the extent of necessary engineering stabilization measures required for project construction. We did not agree with the proposed construction approach to determine the extent of corrective grading required during mass grading operations.

In order to evaluate the type and extent of ground stabilization measures required for roadway construction, we recommended that the roadway alignment and adjoining slopes first be mapped by a Certified Engineering Geologist. Given a Northern California Office
330 Village Lane
Los Gatos, CA 95030-7218
( 408) 354-5542 • Fax ( 408) 354-1852
e-mail: [email protected] www.cottonshires.com
Central California Office
6417 Dogtown Road
San Andreas, CA 95249-9640
(209) 736-4252 • Fax (209) 736-1212
e-mail: [email protected]
351
Gilbert Yau
Page2
August 13, 2008
B4030C
favorable assessment of roadway construction feasibility, the initial geologic mapping was to be followed by necessary subsurface exploration and evluation of specific engineering solutions. Our previous letter pointed out many areas where the roadway alignment was impacted by existing landslides and the potential for additional slope instability.

SITE CONDITIONS
The southern portion of the roadway easement and adjoining terrain is characterized by steep (40 to 50 percent inclination), southwest-facing native hillslopes and drainage swales, and the northern portion by steep to very steep (50 to 70 percent inclination), northwest-fach1g native hillslopes and drainage swales. Previous cut and fill grading operations have resulted in the creation of an unpaved access road.

Unsupported cut slopes along the inboard edge of the unpaved road vary in height from 4 to 10 feet and are generally precipitous (over 80 percent inclination). Fill prisms of generally 3 to 5 feet in depth appear to have been placed on the outboard edge of the unpaved road and existing fill slopes are steep to very steep (50 to 70 percent inclination). Surface drainage is characterized by uncontrolled sheetflow along hillslopes and is intercepted by northwest- and southwest-flowing drainage swales.

The property is generally underlain by shallow bedrock of the Franciscan Complex (tan to dark gray, thin to thick bedded sandstone and siltstone). The bedrock appears to be overlain by colluvium (brown sandy silty clay with rock fragments) varying in thickness from 5 to 15 feet on slopes and in drainage swales, but is generally less than 5 feet in the vicinity of ridge crests. According to the City's Engineering Geologic Map, two active landslides (Als) are located on the northwest-facing slope and extend from above upon the unpaved road. Multiple debris flow scarps, flow paths and areas of severe soil creep are mapped on slopes below the unpaved road. The City's Ground Movement Potential Map indicates that five "Pdf" zones are located on the property, with three of these zones crossing the alignment of the proposed roadway.

Furthermore, two active shallow landslide (Ms) and two potentially deep landslide (Pd) zones cross the proposed road alignment. The remainder of site slopes are designated as potentially unstable with respect to shallow fai1ures (Ps). "Pdf" is defined as "steep to very steep terrain mantled with a thick cover of soil, colluvium, and landslide debris ... susceptible to rapid downslope movement in the form of debris flows or earth flows". "Ms" is defined as "moving shallow landslides, commonly less than 10 feet in thickness and slow moving". "Pd" is defined as "relatively unstable landslide debris, commonly more than 10 feet in thickness on moderately steep to very steep slopes ... susceptible to renewed deep landslide movement". "Ps" is defined as "relatively unstable material including landslide debris, slope materials, and weak bedrock, commonly less than 10 feet in thickness ... susceptible to shallow landsliding, slumping and soil creep".

During our recent site inspection, we observed several shallow lai--:.dslide scarps (less than 10 feet in height) located from 20 to 100 feet below the unpaved road on the northwest-facing slopes. Some of the scarps had associated debris flow channels COTTON, SHIRES & ASSOCIATES, INC.
352
Gilbert Yau
Page3
August 13, 2008
B4030C
extending further downslope. Deeply incised erosional gulleys were observed below the roadway alignment. Slope failure and erosional processes have reduced the unpaved road to the width of a footpath in multiple areas. Observed landslides and debris flows are generally consistent with the "Pdf" and "Ms'' zones depicted on the City's ground movement potential map. However, areas of more recent landsliding were identified beyond what is depicted on the 1985 City Geologic Map. Traces of the San Andreas fault and _the Belmont Hill fault are located 2.1 miles southwest and 1.4 miles east of the subject property, respectively.

CONCLUSIONS AND RECOMMENDED ACTION
Romig Engineers has completed detailed genlneic m;:;pp1ne :_-,f e.'-'.i::t•.ng landslides presenting slope instability constraints to the establishment of a Monte Cresta Through Road. Based on evaluation of aerial photographs taken since 1937, the consultant has identified major slope changes that appear to involve landslides ranging in depth from approximately 10 to 25 feet (or more). These areas of large scale landsliding are particularly evident in the northern two-thirds of the roadway alignment (north of station 17+50). The Project Geotechnical Consultant concludes that deep-seated landsliding will continue to occur, impacting ground beneath the roadway alignment. Geologic cross sections have been prepared illustrating extensive landslide development above and below the potential roadway alignment. The consultant concludes that construction of a safe, relatively low maintenance roadway north of Station 17+50 is not currently feasible or reasonable. In addition, the consultant finds that development of stable residential building areas along this portion of the roadway are economically impractical or impossible to justify.

We concur with the assessment of Romig Engineers that no significant geotechnical constraints (beyond standard mitigation design) are apparently present along the first 104-foot segment of the road extension from the end of the existing roadway pavement to the Campbell property (stations 10+00 to 11 +04). We also concur that severe geologic and geotechnical constraints (primarily deep-seated landsliding) are present beneath much of the northern road alignment. These conditions probably include extensive landslide deposits greater than 25 feet in depth. Existing slope instability of this magnitude results in serious questions about the economic feasibility of establishing a stable roadway or viable house sites along the northern portion of the roadway easement. We are in fundamental agreement with the basic findings of the referenced Jm1e 2008 Geologic and Geotechnical Report.

LIMITATIONS
This supplemental geotechnical peer review has been performed to provide technical advice to assist the City with discretionary permit decisions. Our services have been limited to review of the documents previously identified, and a visual review of the property. Our opinions and conclusions are made in accordance with generally

COTTON, SHIRES & ASSOCIATES, INC
353
Gilbert Yau
Page4
August 13, 2008
B4030C
accepted pri...-1ciples and practices of the geotechnical profession. This warranty is in lieu of all other warranties, either expressed or implied.

TS:DTS:J A:kd
Respectfully submitted,
COTTON, SHIRES AND ASSOCIATES, INC.

CITY GEOTECHNICAL CONSULTANT
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David T. Schrier
Principal Geotechnical Engineer
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COTTON, SHIRES & ASSOCIATES, Ii'iC. 354

GEOLOGIC AND GEOTECHNICAL ENGINEERING

FEASIBILITY STUDY

MONTE CRESTA DRIVE THROUGH ROAD

BELMONT, CALIFORNIA
June 2008
Prepared for
Mr. Damon Campbell
10 Winding Way
San Carlos, California 94070
Project No. 2092-1
355
ROMIG ENGINEERS, INC.

GEOTECHNICAL & ENVIRONMENTAL SERVICES
Mr. Damon Campbell
10 Winding Way
San Carlos, California 94070
Dear Mr. Campbell:

June 30, 2008
2092-1
RE: GEOLOGIC AND GEOTECHNICAL

ENGINEERING FEASIBILITY STUDY

MONTE CRESTA DRIVE THROUGH ROAD

BELMONT, CALIFORNIA
At your request, we have performed a geologic and geotechnical engineering feasibility study to investigate the possibility of constructing a through road connection along the 1,800-foot-long easement between the existing improved and paved ends of Monte Cresta Drive in Belmont, California. The accompanying report summarizes· the. findings and conclusions from our review of available information, study of aerial photographs, geologic field mapping, and geologic and geotechnical engineering analysis regarding the hazards associated with design ,and construction of a City-owned roadway along the easement for the Monte Cresta Drive through road.

On the basis our feasibility study, we have concluded that it is not feasible to design and construct a safe and relatively maintenance-free roadway along ·the entire through road alignment. Construction of the proposed 104-foot-long extension of Monte Cresta Drive to the Campbell property at the southern end of the road alignment is reasonable and feasible, however, as determined previously by others.

We refer you to the text of our report for a summary of our geologic and geotechnical engineering findings and conclusions regarding the feasibility of constructing a safe and relatively maintenance-free through road versus the currently proposed 104-foot-long road extension to the Campbell property.

Thank you for the opportunity to work with you on this project. Please call us if you have any questions or comments about site conditions or the conclusions from our feasibility study.

Very truly yours,
ROMIG ENGINEERS, INC.
/44 u.�-h,.l
Robert G. Wilson III, C.E.G.

Copies: Addressee (5)
RGW:RGWIII:GAR:sb
1390 El Camino Real, Second Floor • San Carlos, California 94070 • (650) 591-5224 • Fax (650) 591-5251 356
ROMIG ENGINEERS, INC.

GEOLOGIC AND GEOTECHNICAL ENGINEERING

FEASIBILITY STUDY

MONTE CRESTA DRIVE THROUGH ROAD

BELMONT, CALIFORNIA
PREPARED FOR:

MR. DAMON CAMPBELL
10 WINDING WAY
SAN CARLOS, CALIFORNIA 94070
PREPARED BY:

ROMIG ENGINEERS, INC.
1390 EL CAMINO REAL, SECOND FLOOR
SAN CARLOS, CALIFORNIA 94070
JUNE 2008
357
ROMIG ENGINEERS, INC.

TABLE OF CONTENTS
Page No.

Letter of transmittal
Cover Sheet

TABLE OF CONTENTS
INTRODUCTION..........................................................................................................1 Project Description ................................................................................................2 SCOPE OF FEASIBILITY STUDY..............................................................................2 LIMITATIONS ..............................................................................................................3 FINDINGS .....................................................................................................................4 Brief Site History...................................................................................................4 Previous Investigations and Reports by Others.....................................................5 Conditions Along Through Road Alignment ........................................................6 GEOLOGIC CONDITIONS AND HAZARDS.............................................................7 Regional Geology..................................................................................................7 Faulting and Seismicity .........................................................................................8 Table 1. Earthquake Magnitudes and Historical Earthquakes .....................8 Site Geologic Conditions.......................................................................................9 Aerial Photographs..............................................................................................10 Site Reconnaissance and Geology.......................................................................12 Slope Stability......................................................................................................14 REQUIRED MITIGATION MEASURES ..................................................................15 Station 10+00 to 11+04 (Campbell Road Extension) .........................................15 Station 11+04 to 17+50 (Campbell Road Extension to Spur Ridge) ..................16 North of Station 17+50 (North of Spur Ridge)....................................................17 GEOLOGIC AND GEOTECHNICAL CONCLUSIONS ...........................................18 Station 10+00 to 11+04 (Campbell Road Extension) .........................................18 Station 11+04 to 17+50 (Campbell Road Extension to Spur Ridge) ..................18 North of Station 17+50 (North of Spur Ridge)....................................................19 SUMMARY.................................................................................................................20

REFERENCES
FIGURE 1 - VICINITY MAP
FIGURE 2 - VICINITY GEOLOGIC MAP
FIGURE 3 - GROUND MOVEMENT POTENTIAL MAP
FIGURE 4 - SITE PLAN AND ENGINEERING GEOLOGIC MAP
FIGURE 5 - ENGINEERING GEOLOGIC HAZARD MAP
FIGURE 6 - GEOLOGIC CROSS SECTION A-A’
FIGURE 7 - GEOLOGIC CROSS SECTION B-B’
358
ROMIG ENGINEERS, INC.

GEOLOGIC AND GEOTECHNICAL ENGINEERING

FEASIBILITY STUDY
FOR

MONTE CRESTA DRIVE THROUGH ROAD

BELMONT, CALIFORNIA

INTRODUCTION
This report presents the findings and conclusions from our geologic and geotechnical engineering feasibility study addressing the extension of Monte Cresta Drive versus the conceptual Monte Cresta Drive through road in Belmont, California. The easement for the through road is located on the eastern side of San Juan Canyon approximately as shown on the Vicinity Map, Figure 1, the Vicinity Geologic Map, Figure 2, and the Ground Movement Potential Map, Figure 3.

Background information regarding the proposed Monte Cresta Road Improvement Plan (Application ID 2000-1085) for a 104-foot-long extension of Monte Cresta Drive to access Mr. Damon Campbell’s property at the southern end of the through road alignment is presented in a letter to the City of Belmont’s Community Development Director, dated August 16, 2007, prepared by Briscoe, Ivester & Bazel, LLP. One of the conditions that must be satisfied to allow the proposed road extension to the Campbell property is that construction of a 1,800-foot-long through road between the existing paved portions of Monte Cresta Drive is unreasonable due to physical and/or economic constraints.

The City of Belmont’s response to the August 16, 2007 letter regarding the Monte Cresta Road Improvement (extension) Plan was summarized in a letter to Briscoe, Ivester & Bazel, LLP, dated December 21, 2007. The City requested clarification of discrepancies between two previous consultant reports: one prepared in October 2001 indicating that through road design and construction was feasible; and one prepared in January 2006, after additional study was performed, indicating that design and construction of the through road was not feasible or reasonable.

The purpose of the feasibility study described in this report was to provide an updated and more complete investigation to address whether it would be reasonable and feasible to design and construct the through road (versus the road extension) without incurring excessive construction cost, environmental damage during construction, and the risk of continued landsliding in the area that could result in large and potentially-unpredictable maintenance cost to the city of Belmont over a service life of at least 50 years. 359
Mr. Damon Campbell Monte Cresta Drive Through Road Page 2 of 20 ROMIG ENGINEERS, INC.

Project Description
The alignment of the 1,800-foot-long, right-of-way and easement for the unimproved section of Monte Cresta Drive described in this report as the “through road” is shown on preliminary plans for the through road, dated September 14, 2001, prepared by Luzuriaga Taylor, Inc. (LTI). This preliminary road alignment is the alignment shown on the Vicinity Geologic Map, Figure 2, the Ground Movement Potential Map, Figure 3, the Site Plan and Engineering Geologic Map, Figure 4, and the Engineering Geologic Hazard Map, Figure 5, included in this report.

Road Improvement Plans, dated October 24, 2002, were prepared for Mr. Campbell’s proposed 104-foot-long road extension from the existing paved road at the southern end of the through road alignment. The roadway cross-sections in these road improvement plans specified a width of 35 feet from back-of-curb to back-of-curb, and a total width of

41.5 feet from face of retaining wall to face of guardrail allowing for a narrow planter along the upslope side of the roadway. The width of the through road alignment shown on the figures in this report is 40 feet. Due to the steep to very steep hillside topography, particularly along the portion of the road alignment north of the proposed 104-foot long road extension, preliminary analysis indicates that retaining walls with exposed-face heights ranging from 4 to 8 feet would be required along the majority of both sides of the roadway to achieve a 30- to 40-foot-wide roadway and sidewalk cross-section.

The conceptual Monte Cresta Drive through road could potentially provide access to 37 undeveloped lots along the sides of the road alignment. Preliminary plans for the through road project prepared in 2005 by LTI indicated possible locations of access driveways to these lots. These plans were prepared without consideration of the specific geologic and geotechnical mitigation measures that would be required for access to these lots and for development of safe, stable building areas on the lots. Many of the lots north of the road extension to the Campbell property are underlain by landslides and/or other unstable soil conditions and have difficult to severe technical and economic challenges to overcome to allow safe access and stable conditions for site development. The number of lots that could be safely accessed and developed north of the road extension to the Campbell property without design and construction of extensive mitigation measures is unknown.

SCOPE OF FEASIBILITY STUDY
The scope of our work for this feasibility study was to review and evaluate geologic and geotechnical conditions along the through road alignment and, on the basis of this information, to develop an opinion about whether or not conditions along the through road alignment could be mitigated in a reasonable and sufficient manner. This work was performed in accordance with our agreement for professional services with Mr. Damon Campbell, dated February 5, 2008, and consisted of the following work. 360
Mr. Damon Campbell Monte Cresta Drive Through Road Page 3 of 20 ROMIG ENGINEERS, INC.
• Review of information from previous studies supplied for our review, and available reports and information in our files pertinent to the geologic, geotechnical, and seismic conditions in the vicinity of the through road alignment. • Review of panchromatic black and white stereo pairs of aerial photographs of the through road alignment and adjacent areas.
• Geologic reconnaissance and field mapping of the through road alignment and the immediately adjacent properties. Our field reconnaissance and geologic mapping focused on the on-site and near-site features that could affect design, construction, performance, and maintenance of the through road connection. • Geologic and geotechnical engineering analysis and evaluation of available published and unpublished information and field data to develop an opinion and conclusions regarding the feasibility and reasonableness of constructing the through road. • On-site meeting with an engineering geologist from Cotton, Shires & Associates, Inc., the city’s peer review geologist, to review and discuss site conditions, slope stability, constraints to through road construction, and required mitigation measures. • Preparation of this geologic and geotechnical engineering feasibility report presenting the findings and conclusions from the feasibility-level investigation described herein.

This report was prepared to summarize geologic and geotechnical conditions and hazards along the through road alignment, and to determine to what extent these hazards would affect design, construction, and long-term performance of the Monte Cresta Drive through road.

LIMITATIONS
This report has been prepared for the exclusive use of Mr. Damon Campbell for specific application to presenting geologic and geotechnical engineering feasibility-level findings and conclusions regarding the Monte Cresta Drive through road connection in Belmont, California. We make no warranty, expressed or implied, except that our services have been performed in accordance with the geologic and geotechnical engineering principles and practices generally accepted at this time and location. This report was prepared to summarize the findings and conclusions from the feasibility-level study described herein.

In the event there are any changes in the nature, design, or location of the through road alignment, the conclusions presented in this report should not be considered valid without review and evaluation of the changes, performing additional study, and developing updated conclusions.

The analysis and conclusions presented in this feasibility study report are based on site conditions as they existed at the time of our investigation; the preliminary roadway 361
Mr. Damon Campbell Monte Cresta Drive Through Road Page 4 of 20 ROMIG ENGINEERS, INC.
alignment described herein; and review of readily available reports and information relevant to the site conditions. The conclusions and mitigation measures described in this report are considered conceptual. Changes in the information or data gained from any of the sources used for this feasibility study could result in changes in our conclusions. If such changes occur, we should be advised so that we can review this feasibility report in light of those changes.

The subsurface exploration, laboratory testing, and engineering analysis that would be required to develop detailed, design-level recommendations for design and construction of the through road, and for development of sites along the through road alignment, were not proposed or performed as part of this feasibility study.

FINDINGS
Brief Site History
Development in the vicinity of the through road alignment and on the previously undeveloped section of the Monte Cresta Drive hillside began before 1937. By 1937, Monte Cresta Drive and roadways south, north, and east of the through road alignment had been rough-graded for the beginning of a subdivision. Monte Cresta Drive was located along the western, downhill boundary of this subdivision. It is doubtful that earthwork construction performed for the original rough-grading met minimum current standards.

By the early 1950’s, the subdivision roadways in the area had been paved except for the currently undeveloped 1,800-foot-long section for the Monte Cresta Drive through road.

Approximately six houses had been constructed along All View Way uphill of the undeveloped section of Monte Cresta Drive, and other homes had been constructed within other portions of the subdivision. Between the mid and late 1960’s, the surrounding subdivision was built-out and appears roughly as it does in 2008, approximately 40 years later.

Deterioration of the rough-graded portion of the Monte Cresta Drive through road and adjacent hillside began soon after rough-grading and development of the adjacent subdivisions. Excavation of a large cut slope for homes along Alhambra Drive took place during the late 1960’s. As a result of the grading, two small debris flows occurred between the top of the cut slope and the through road alignment. Deterioration of the rough-graded section of Monte Cresta Drive occurred progressively during the 1970’s, 1980’s, and 1990’s, particularly within the northern 60 percent of the alignment, resulting in the conditions that are present along the roadway in 2008. 362
Mr. Damon Campbell Monte Cresta Drive Through Road Page 5 of 20 ROMIG ENGINEERS, INC.

Previous Investigations and Reports by Others
Earth Mechanics Consulting Engineers (EMCE) performed a geotechnical investigation of the through road alignment and presented the results in their report, dated October 18, 2001, titled “Geotechnical Investigation, Planned Monte Cresta Drive Extension, Belmont, California.” This report referenced William Cotton and Associates’ 1985 mapping of the San Juan Canyon Study Area and indicated that geologic maps of the area did not show active landslides along the road alignment. EMCE indicated they did not observe evidence of active slope instability along the road alignment except for some minor instability of over-steepened cut slopes. As part of their study, 11 exploratory borings were drilled to depths of about 1 to 15½ feet. Four of the borings were clustered at the southern end of the road alignment adjacent to Mr. Campbell’s property and the remaining seven borings were spaced at approximate 200 foot, evenly-spaced intervals along the remainder of the through road alignment. Accurate locations of the borings along the Monte Cresta Drive through road alignment could not be determined from the Boring Location Map in the EMCE report. On the basis of this investigation, EMCE concluded that it would be feasible to construct the through road.

Cotton, Shires and Associates, Inc. (CSA), the City’s geologic and geotechnical peer review consultant, reviewed the October 18, 2001 report by EMCE and summarized their review comments in a Geologic and Geotechnical Review letter dated January 23, 2002.

CSA referred to the Ground Movement Potential and Geologic Hazard Policy Map adopted in March 1988 by the City of Belmont, which was based on geologic source information summarized by William Cotton and Associates (WCA, 1985). CSA indicated that five “Pdf” (potential debris flow) zones and two active landslides were located along the road alignment as shown on the City of Belmont’s Ground Movement Potential and Geologic Hazard Policy Map (March, 1988). CSA also noted that two areas along the alignment were mapped as “Pd” (potentially deep) landslide zones, which pose a significant hazard due to the potential for deep-seated landsliding. After further evaluation, CSA staff identified three additional landslides not included on the original Ground Movement Potential and Geologic Hazard Policy Map. CSA noted that the remainder of the hillslope the through road traverses has been designated as a “Ps” zone, which indicates potential instability due to shallow slope failure.

In their January 23, 2002, peer review letter, CSA recommended detailed engineering geologic mapping of the through road alignment, preparation and analysis of one or more geologic cross-sections, and development of engineering geologic opinions and conclusions prior to performing more detailed subsurface exploration in potential hazard areas. CSA indicated this study would be needed to develop recommendations for remedial grading and slope stabilization (among other things) to address the extent of work required for through road construction.
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After follow-up study was performed, EMCE prepared letters, dated January 12, 2006 and November 20, 2006, indicating the through road could not be reasonably constructed in a safe and stable manner.

The feasibility study described in this report completes the geologic study recommended in 2002 by CSA. We have identified current geologic conditions and hazards at the site and evaluated their potential effect on the long term stability of the Monte Cresta Drive through road. Supplemental subsurface exploration was not performed for this feasibility study. A more in-depth design-level study including subsurface exploration, laboratory testing, evaluation of field and laboratory test data, and detailed stability analyses, would be required to develop design-level recommendations for design, construction, and mitigation of geologic hazards along the through road alignment.

Conditions Along Through Road Alignment
The Monte Cresta Drive through road alignment is located in hillslope terrain on the west and northwest-facing slopes of a ridge near the base of the Santa Cruz Mountains in the San Juan Hills. The through road alignment is within the San Juan Hills Canyon Study Area described by William Cotton and Associates (WCA, 1985). Site topography varies from relatively flat along ridge crests to steep to very steep on the hillsides, particularly in the northern 60 percent of the alignment. Slope inclinations in some areas are as steep as approximately 1:1 (horizontal:vertical). Some of the original cut slopes are near-vertical.

The through road alignment is located on one of the less developed hillsides in the San Juan Canyon Study Area. Portions of the hillside are heavily vegetated and overgrown with native grasses and weeds, large developed patches of shrubbery, and numerous groves of various types of trees indigenous to this hillside region.

The original road along the through road alignment was rough-graded prior to 1937 by cutting and filling. The upslope side of the road was cut into the hillside, and the soil and rock materials generated by cutting were placed along the outboard, downslope side of the roadway. Based on our field mapping, it appears the original rough-grading included cuts up to 12 feet high, or more, and fills as deep as about 10 feet. The cuts appear to have been excavated with gradients typically in the range of about 1:1 to 1.5:1 (horizontal:vertical). The fills appear to have been constructed with slope gradients of approximately 1.5:1 to 2:1 (horizontal:vertical). We are not aware of any records that document ground preparation or compaction of the fill material. In our opinion, it would be reasonable to assume that the original ground preparation, rough-grading, and fill compaction would not meet current minimum standards for earthwork construction, particularly in the areas that were underlain by unstable slopes and landslides at the time of the original grading.
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The through road alignment traverses a prominent spur ridge that is perpendicular to the main hillside. This spur ridge is located approximately 725 feet from the southern end of the through road alignment. Although landslides and areas of instability are present south of this spur ridge, conditions south of the spur ridge are considerably more favorable for road construction, access to lots, and residential construction on individual lots than north of the spur ridge where numerous landslides, mass wasting, and areas of potential deep instability are present. This spur ridge and road stationing shown on LTI’s September 14, 2001 Road Improvement Plans are referred to in subsequent sections of this report. The spur ridge and some road stationing reference points are shown and labeled on Figure 4.

Cut slopes extending to heights of 12 feet or more are continuous along the majority of the upslope side of the roadway south of the spur ridge. These cut slopes are generally inclined at a gradients varying from 1.5:1 (horizontal:vertical) to near-vertical locally.

Within the southern portion of the alignment, bedrock is exposed along the majority of the cut face, fills up to about 6 to 8 feet high are present, and surface erosion is limited.

North of the spur ridge, the majority of the original rough-graded slopes have been removed or modified by the landsliding and mass wasting that has occurred since 1937.

Bedrock in the northern portion of the alignment is only exposed in limited areas where the cut slopes have not been removed or modified. Landsliding and mass wasting has resulted in significant removal of material and has reduced the majority of the original roadway north of the spur ridge to the width of a footpath The fills that remain along the downslope side of the roadway alignment vary in thickness from about 3 to 8 feet, and have variable slope gradients ranging from approximately 1:1 to 2:1 (horizontal:vertical).

Surface erosion is evident on the cut and fill slopes, and has contributed to local downcutting of the road due to years of uncontrolled surface water runoff. Surface erosion is particularly noticeable at some of the swales and gully crossings, where erosion gullies several feet deep have developed.

GEOLOGIC CONDITIONS AND HAZARDS
Regional Geology
The site is located within the central region of the Coast Ranges Geomorphic Province, which extends from the Oregon border south to the Transverse Ranges. Subparallel, northwest-trending mountain ranges, such as the Central Santa Cruz Mountains and intervening valleys, characterize the general topography. The through road alignment is located on a northwest-facing ridge in the Santa Cruz Mountains. The region has undergone a complex geologic history of volcanic activity, folding, faulting, uplifting, landsliding, erosion, and sedimentation.
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Faulting and Seismicity
There are no mapped through-going faults within or adjacent to the through road alignment, and the alignment is not located within an Alquist-Priolo State of California Earthquake Fault Zone (formerly known as a Special Studies Zone), an area where there is a potential for fault rupture. The closest active fault to the site is the San Andreas fault, located approximately 1.8 miles southwest of the property. Evidence of active fault traces trending toward or across the through road alignment was not detected during our study. Therefore, active faults are not believed to existing within the through road alignment, and the potential for surface rupture from faulting within the Monte Cresta Drive through road alignment is remote.

The San Francisco Bay Area is an active seismic region. Earthquakes in the region result from strain energy constantly accumulating because of the northwestward movement of the Pacific Plate relative to the North American Plate. On average about 1.6-inches of movement occur per year. Historically, the Bay Area has experienced large, destructive earthquakes in 1838, 1868, 1906 and 1989. The faults considered most likely to produce large earthquakes in the area include the San Andreas, San Gregorio, Hayward, and Calaveras faults. The San Gregorio fault is located approximately 9.7 miles southwest of the site. The Hayward and Calaveras faults are located approximately 16.6 and 24 miles northeast of the site, respectively. These faults and the significant earthquakes that have been documented to have occurred on the faults within the Bay Area are listed below in Table 1.

Table 1. Earthquake Magnitudes and Historical Earthquakes Monte Cresta Drive
Belmont, California
Maximum Historical Estimated
Fault Magnitude (Mw) Earthquakes Magnitude
San Andreas 7.9 1989 Loma Prieta 6.9
1906 San Francisco 7.9
1865 N. of 1989 Loma Prieta Earthquake 6.5
1838 San Francisco-Peninsula Segment 6.8
1836 East of Monterey 6.5
Hayward 7.1 1868 Hayward 6.8
1858 Hayward 6.8
Calaveras 6.8 1984 Morgan Hill 6.2
1911 Morgan Hill 6.2
1897 Gilroy 6.3
San Gregorio 7.3 1926 Monterey Bay 6.1
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In the future, property along the through road alignment will undoubtedly experience severe ground shaking during moderate and large magnitude earthquakes produced along the San Andreas or other active Bay Area fault zones. The Working Group on California Earthquake Probabilities, a panel of experts that are periodically convened to estimate the likelihood of future earthquakes based on the latest science and information, concluded there is a 62 percent chance for at least one earthquake of Magnitude 6.7 or larger to occur in the Bay Area by 2031 (Working Group, 2003). The San Andreas fault has the second highest likelihood of producing a large earthquake in the Bay Area, estimated as a 21 percent chance of a Magnitude 6.7 or larger earthquake by 2031. The Hayward fault has the highest likelihood of producing a similar event (27 percent).

The through road alignment is located in an active seismic area. Moderate to large earthquakes are probable along several active faults in the greater Bay Area over a 30 to 50 year design life. Strong ground shaking should therefore be expected several times during the design life of the through road, as is typical for sites throughout the Bay Area.

Monte Cresta Drive and the associated structural improvements should be designed in accordance with current seismic design standards. The probability of earthquake-induced landslides along the through road alignment is more likely where landslides, known unstable ground conditions, and original fills are present. Earthquake-induced differential compaction of the original fill materials is likely unless the original fills are excavated and recompacted.

Site Geologic Conditions
The through road alignment and the general vicinity is underlain by Franciscan Complex bedrock composed of interbedded sandstone and minor shale deposits, as shown on the Vicinity Geologic Map, Figure 2 (WCA, 1985). These Cretaceous-age rocks have been uplifted by tectonic forces, resulting in intense shearing, and pervasively altered and variably weathered, (decomposed) bedrock. Generally, the older rocks have been weathered to form a mantle that includes an accumulation of soil, colluvium, rock debris, regolith, landslides, and materials deposited by mass wasting. The thickness of this overburden material varies greatly along the alignment, ranging from several inches in the southern portion of the alignment to tens of feet north of the spur ridge.

Bedrock on the hillside and along the through road alignment is inconsistent (WCA, 1985). Along the southern portion of the alignment and along the spur ridge, bedrock generally strikes in a northwest to northeast orientation and dips either perpendicular to or into the hillside at angles varying from 7 to 43 degrees. Bedding planes north of the spur ridge are inconsistent and vary greatly. Bedding noted by WCA and observed on the hillside north of the spur ridge dipped at 2 degrees out of the hillside in an adverse dip slope direction.
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The WCA 1985 map described numerous fracture set measurements throughout the study area. The fracture sets were locally homogenous with similar orientations and dip directions. Generally, dips of fracture sets are in adverse dip slope directions, dipping out of the slope at angles varying from 36 to 85 degrees. Some less common fracture orientations were measured at oblique angles to the downhill slope direction or were dipping into the hillside.

WCA (1985) developed a Ground Movement Potential Map that defines specific unstable areas in the San Juan Canyon Study Area (see Figure 3). The descriptions of these unstable areas vary from shallow unstable zones to deep-seated landslide zones. These zones typically outline areas susceptible to mass wasting, such as downslope creep, debris flows, slope wash, earthflows, rock falls, fill failures, shallow landslides, and larger deeper seated landslides. Generally, the mass wasting extends to depths upwards of 10 feet. Based on descriptions from the Ground Movement Potential Map (WCA 1985), the undeveloped section of the Monte Cresta Drive through road is located in potentially unstable areas designated as Ps, Pdf, Ms, and Pd. All defined areas described above include mass wasting and landsliding to depths of 10 feet or less, and in the case of the Pd zones, indicate areas of unstable landslide debris that are more than 10 feet deep including landslides susceptible to renewed deep-seated movement. The Pd zone definition includes the minimum depth of movement, but in many cases the landslides can extend to depths greater than 25 feet, and depending on conditions, can extend to depths of 40 feet or more. Based on site topography and our geologic interpretations, we anticipate that deeper landslides within the northern portion of the road alignment may extend to depths of 25 feet or more.

According to the City of Belmont San Juan Hills Area Plan adopted in March 1988, development of areas located within Pdf, Ms, and Pd ground movement potential zones, such as mapped along significant portions of the Monte Cresta Drive through road alignment, is not permitted unless the hazards are eliminated or sufficiently mitigated.

Aerial Photographs
Ten sets of panchromatic black and white stereo aerial photographs were evaluated and interpreted as part of our feasibility study. Imagery scales ranged from 1:10,000 to 1:23,600. The aerial photographs that were viewed are listed in the section of this report titled “REFERENCES.” The through road alignment and pertinent hillsides were visible on each set of photographs reviewed.

The oldest imagery interpreted was from 1937. The original Monte Cresta Drive roadway had been rough-graded along with roadways for the subdivision north and east of the through road alignment. Monte Cresta Drive was located along the western, downslope 368
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boundary of this subdivision. Some recent shallow debris flow scars were noted on the downslope side of Monte Cresta Drive adjacent to and north of the prominent spur ridge.

The debris scars were in probable fill and originated within fill slopes on the outboard edge of the road. Older landslide deposits were present in slope indentations, canyons, and swales designated as Pdf, Ps, Ms, and Pd zones (WCA, 1985). Hummocky terrain was also noted within a Pdf zone located near the southwest end of the through road alignment. Based on size, the landslides noted on the aerial photographs were judged to be greater than 10 feet in depth and may extend to depths as deep as 25 feet or more.

By 1955, all of the roads that had been rough-graded prior to 1937 were paved except for the unimproved section of Monte Cresta Drive along the through road alignment. Sparse development was noted throughout the subdivision. Six homes had been constructed on All View Way uphill of the through road alignment. Three of the homes had been constructed at the end of All View Way. Grading was required for the construction of the building pads, with fill placed on the down slopesides of the pads. No recent landslides appear to have occurred within the Pdf zones (WCA, 1985) near the south end of the through road alignment. Shallow earth flows and the outline of a larger deep-seated landslide was noted in the canyon and Pdf zone (WCA, 1985) adjacent to and north of the spur ridge. Shallow mass wasting was present in the large slope indentation and Pd zone (WCA, 1985) between the spur ridge and the north end of the alignment.

The 1969 imagery indicated that an approximate 30 feet high continuous cut had been excavated above Alhambra Drive downslope from the southern end of the alignment.

Two shallow debris flows were noted on the hillside between the cut and southern end.

Fill of unknown depth and quality had been placed near the base of a canyon south of the spur ridge. By 1969, the lots on All View Way uphill from the through road alignment had been developed with single-family homes with no remaining vacant properties visible.

By 1981, significant erosion and mass wasting had occurred north of the spur ridge within the geologically complex area that contains two Ms zones, two Pdf zones, and two Pd zones. The entire rough-graded road alignment appeared to have been reduced in width to some degree, with the portion of the road north of the spur ridge reduced to the width of a footpath at numerous locations.

By 1983, shallow landslides and mass wasting had significantly altered the topography within the large canyon adjacent to and southwest of the spur ridge. The rough-graded roadway north of the spur ridge had been further reduced in width by erosion and additional shallow mass wasting, and observation of the roadway alignment obscured by growth of shrubbery.
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Between 1983 and 1985, the footpath-width section of roadway north of the spur ridge was only partially visible due to additional mass wasting, erosion, and vegetation growth.

Landslides, shallow debris flows, and earth flows had occurred between the spur ridge and the north end of the alignment. Fresh head scarps were visible along the outboard edge of the path.

The 1995 imagery depicted the Monte Cresta Drive through road alignment as it generally appears today. Continued mass wasting and landslide movements had occurred within the canyons north of the spur ridge. Boundaries to individual debris flows, earth flows, soil creep, and landslides were not discernable on the hillside and along the alignment within the canyon north of the spur ridge due to additional shallow slope movements and deeper landslide failures within the Pdf, Ms, and Pd zones (WCA, 1985). Landslides were noted within the road alignment in the narrow canyon and the two Pdf zones (WCA, 1985) closest to the northern end of the proposed road extension to the Campbell property.

The imagery that we reviewed and evaluated indicates that significant and major slope changes have occurred along the rough-graded through road alignment since 1937. The recent slope movements, particularly in the northern portion of the alignment, have obscured larger landslide masses that helped form the geomorphology of the hillside the through road traverses. Downslope movement varying from soil creep to shallow landsliding to deep-seated landsliding has occurred and will continue to occur and contribute to the formation of the geomorphology of the hillside traversed by the through road.

Site Reconnaissance and Geology
Engineering geologic site reconnaissance and field mapping was performed on several occasions in March and April, 2008 by Mr. Robert Wilson, C.E.G. The results of this geologic field mapping are shown on the Site Plan and Engineering Geologic Map, Figure 4, and on the Engineering Geologic Hazard Map, Figure 5. On April 18, 2008, we conducted a site meeting and walked the study area with Mr. Ted Sayre, a representative from Cotton, Shires & Associates, Inc., the City of Belmont’s peer review geologist. Our site reconnaissance and field meeting included traversing the entire through road alignment and accessible adjacent upslope and downslope areas to observe, review, and discuss site conditions and slope instability.

The site of the through road alignment is underlain by Franciscan complex bedrock which in the study area is comprised of interbedded massive sandstone and friable fine-grained sandstone. Massive sandstone outcrops are prominent in cut slopes along the existing paved section of Monte Cresta Road leading up to its terminus at the southern end of the 370
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through road alignment. The friable fine-grained sandstone is introduced and becomes the predominant bedrock type exposed on the cut slopes within the study area. The bedrock is generally pervasively sheared, altered, weathered, and fractured, which is typical of the Franciscan complex. However, the spur ridge is composed of massive sandstone and massive sandstone interbeds are present south of the spur ridge.

The massive sandstone was well-indurated, hard, and exhibited a crystalline structure. It varied from thinly to thickly bedded and exhibited three prominent fracture sets. The bedding was fairly consistent within exposures along the southern portion of the through road alignment. The fine-grained sandstone was thinly bedded, contained fines, was hard and indurated, and exhibited a friable and blocky structure. The rock crumbled into small blocks averaging about 2 inches in size.

Bedrock was measured striking to the northwest and dipping either into or perpendicular to the slope at angles of 14 to 53 degrees along the nearby ridge crest and in exposures within the southern portion of the through road alignment. Bedding was more difficult to determine within the friable sandstone, but generally followed the general bedding trend.

Fracture sets were consistent in the cut slope near the southern end of the through road but became inconsistent and tended to vary widely throughout the remainder of the through road study area, which is typical of the Franciscan Complex. Some fracture sets were dipping in adverse directions out of the slope at angles that varied from 20 to 85 degrees. However, fracture sets were also noted dipping into the hillside where exposed throughout the study area.

Inclusions were observed on both bedding and fracture surfaces. One thin inclusion, composed of serpentine approximately 1-inch thick, was noted along a bedding plane in the friable sandstone. The inclusion may be the result of either weathering of a shale lens, or more likely from an inclusion fluid in-fill infused during the orogenic mountain building process that formed the Central Santa Cruz Mountains and San Juan Canyon.

A 2 to 2½-inch laterally continuous inclusion was noted within an exposed massive sandstone outcrop on the road base and crest of the spur ridge. The inclusion, representing a fluid in-fill, was located along a steeply-dipping to near-vertical fracture surface. The inclusion (composition unknown) was hard and exhibited minor weathering.

The occurrence of inclusion fluid in-fills noted along a small area in comparison to the entire study area and hillside, indicates the in-fills probably occur frequently on fracture and bedding surfaces across other portions of the hillside. In-fills will exhibit varying weathering characteristics and will influence slope stability depending of their composition.
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Slope Stability
During our site reconnaissance and geologic field mapping, numerous landslides and zones of mass wasting were noted and mapped along the through road alignment, particularly north of the spur ridge and Station 17+50. The mapped landslides are shown on Figures 4 and 5.

As shown on Figures 4 and 5, no significant features that could not be readily mitigated were identified along the proposed 104-foot-long road extension to the Campbell property (i.e. from Station 10+00 to Station 11+04).

Between the northern end of the proposed road extension and the spur ridge (i.e. from Station 11+04 to 17+50), active landslides were noted and mapped along both the upslope and downslope sides of the road alignment, predominantly within and immediately adjacent to the previously mapped Pdf zones. Most of these landslides were estimated to be relatively shallow, ranging in depth from about 10 to 15 feet.

The landslides and mass wasting north of the spur ridge (north of Station 17+50) ranged from shallow sloughs and slumps located on cut slopes, to shallow landslides, to large deep-seated landslide masses filling the canyons and swales. The locations of the landslides and mass wasting generally corresponded to the Pdf, Ms, and Pd zones shown on the “Ground Movement Potential Map, San Juan Canyon Study, Belmont, California” (WCA, 1985). The unstable materials north of the spur ridge vary in thickness and depth from a foot or so up to approximately 25 feet or more. The slope failures were so prevalent and complex in some areas that boundaries to creep zones, debris flows, earth flows, fill failures, and landslides were locally difficult to determine. Recent landsliding has obscured many of the older slope failures and landslides. The areas of landsliding and slope instability were identified and described as mass wasting where the slope failures were so complex that individual features were undeterminable. Many of these features have occurred since the time roadway was rough-graded.

The slope failures north of the ridge varied from several feet in depth to obscured older landslides that may extend to depths of 25 feet or deeper. Many of the failures were consistent with the definitions used on the William Cotton and Associates’ Ground Movement Potential Map (1985). Failures within the Pdf zones were generally judged to be no more than 10 feet thick although some of the landslides within the Pdf zones were judged to be thicker than 10 feet. Recent active landslides and slope failures varied from 5 to 50 feet wide, up to 150+ feet long, and extended to depths of 5 to 15 feet. Small failures within the outboard side of the existing road/footpath exhibited fresh head scarps up to 10 feet high, remnant flow paths, side scarps, and lacked significant developed vegetation.
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Geologic Cross-Sections A-A and B-B, Figures 6 and 7, illustrate surface and interpreted subsurface conditions at two of the mapped landslide locations in the northern portion of the alignment. The locations of these Geologic Cross-Sections are shown on Figure 4 and

5. These cross-sections indicate the general trend of deeper landsliding downslope of the road alignment, which is expected to contribute significantly to the depth and cost of the retaining structures required along the downslope side of the road alignment.

Landslides that occurred during the formation of the canyons can be considered to be deeper-seated landslides that extend deeper than the minimum depth indicated for the Pdf and Pd zones by WCA (1985). Based on geomorphic conditions, some of the deep-seated landslides north of the spur ridge could be as deep as approximately 40 feet. With the numerous active shallow failures obscuring these larger landslide masses, it is difficult to determine landslide activity, whether active, incipient, or dormant. Based on the present instability within the northern canyons and swales, these larger landslides should probably be considered active, or at the very least, incipient landslides. Deep incipient landslides are capable of reactivating and exhibiting movement on the order of at least several feet during major earthquakes or during periods of prolonged, heavy rainfall. The overall stability of slopes is also dependent on the structural components of the bedrock, and the occurrence of weak lenses or layers on either bedding or fracture surfaces can contribute to or cause deep-seated movement.

The slope failures and landslides shown on Figures 4 and 5 are based on our recent geologic field mapping, review of available literature and documents, discussions with Mr. Ted Sayre of Cotton, Shires and Associates, Inc. during our April 18, 2008 field meeting, and review of stereo aerial photographs. Slope movements, slope failures, and landslides mapped in the field and depicted on Figures 4 and 5 obscure many of the other failures that have occurred along the Monte Cresta Drive through road alignment.

REQUIRED MITIGATION MEASURES
Based on the work performed for this feasibility study, we anticipate that at least the following mitigation measures will be required to construct the through road or a road extension.

Station 10+00 to 11+04 (Campbell Road Extension)

1. Excavation and recompaction of existing fills and construction of retaining walls along the downslope side of the roadway, where required.

2. Excavation of cut slopes to a flatter, more stable configuration, where required, and/or construction of retaining structures along the upslope side of the roadway. 373
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3. Construction of surface and subsurface drainage systems for the road extension, structural fills, and retaining structures.

4. Design and implementation of a Storm Water Pollution and Prevention Plan during earthwork, and retaining wall and roadway construction.

5. Construction and maintenance of relatively erosion-resistant surfaces along existing and proposed cut and fill slopes along the road extension.

Station 11+04 to 17+50 (Campbell Road Extension to Spur Ridge)

1. Excavation and recompaction of all existing fill along the road alignment.

2. Construction of retaining structures for all landslides, and/or excavation and repair of all landslides, shown on the Site Plan and Engineering Geologic Map, Figure 4, where the presence of these landslides could affect the stability of the roadway.

3. Reconstruction of over-steepened cut slopes and failed portions of cut slopes.

This work would consist of removing unstable materials, flattening cut slopes to a stable gradient, and constructing structural retaining systems, where necessary.

4. Construction of retaining walls along the upslope and downslope sides of the road alignment, where needed. The retaining walls will need to be designed and constructed in a way that does not interfere with or preclude future access to individual lots along this portion of the alignment.

5. Construction of surface and subsurface drainage systems for the road alignment, structural fills, and retaining structures.

6. Design and implementation of a Storm Water Pollution and Prevention Plan throughout all phases of earthwork, and retaining wall and roadway construction.

7. Construction and maintenance of relatively erosion-resistant surfaces along existing and proposed cut and fill slopes along the road alignment.

8. Proper planning, design, and construction of a road extension from Station 11+04 to 17+50 will be strongly influenced by the development intentions and plans prepared and submitted by individual property owners. The mitigation measures required for a road extension along this section of the alignment will also be highly dependent on the specific lot access and development plans for properties along the alignment prepared by other consultants and designers in the future. 374
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North of Station 17+50 (North of Spur Ridge)
Significant geologic hazards, including deep-seated landslides, are present along this northern portion of the alignment and on many of the adjacent lots. The mitigation measures described below for the northern portion of the through road will also be required to construct safe access and stable building areas on the adjacent lots. On some of the lots, it may not be economically feasible or justifiable to attempt to construct suitable building sites. By listing the following mitigation measures for this portion of the through road, we do not mean to imply that design and construction of the mitigation measures will be practical, reasonable, or affordable.

1. Perform all of the mitigation measures described above for the southern portion of the road alignment. Reconstruction of the fills and numerous landslide deposits north of Station 17+50 is expected to be very difficult, extensive, and possibly cost-prohibitive.

2. Reconstruction of the failed cut slopes north of Station 17+50 is expected to be difficult and extensive since slope instability and landslides extend well upslope from the face of the original cut along the majority of the alignment. Cut slope reconstruction in at least some areas will probably need to include construction of temporary slope support, installation of extensive subsurface drainage systems, and design and construction of permanent structural support systems.

3. Repair of all landslides and/or construction of structural support systems for all of the landslides shown on Figure 4. At a minimum, heavily-reinforced cast-in-place concrete piers are expected with some sections requiring tie-backs. Based on the slopes and subsurface conditions downslope of the road alignment shown on the Geologic Cross-Sections, Figures 6 and 7, structural support would be expected to consist of closely-spaced, soldier beams installed in large diameter pier holes and laterally supported with tie-backs. Where the landslides are deeper than approximately 20 to 25 feet, the structural support systems are expected to be massive and quite expensive, particularly along the downslope side of the roadway where fill will be placed to raise existing grade.

4. Construction of stout retaining walls along the entire upslope and the downslope sides of the road alignment. These retaining wall systems will need to be integrated with design and construction of the structural support systems for the landslides described above. The retaining walls and structural support of landslides will need to be designed and constructed in a way that does not interfere with or preclude future access to individual lots along the alignment. 375
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5. Design and construction of comprehensive surface and subsurface drainage systems for the road alignment, structural fills, and retaining structures. These drainage systems will need to control and dispose of storm water runoff from the roadway, the roadway easement, and the properties along the upslope side of the alignment. On-site disposal of storm water runoff will not be possible due to the steepness and marginal stability of the slopes in this portion of the road alignment.

6. Design and implementation of a comprehensive Storm Water Pollution and Prevention Plan through-out all phases of earthwork and remedial grading, construction of temporary and permanent structural support systems, construction of surface and subsurface drainage systems, and roadway construction.

7. Construction and maintenance of relatively erosion-resistant surfaces along all existing and future cut and fill slopes along both sides of the alignment.

GEOLOGIC AND GEOTECHNICAL CONCLUSIONS
Based on the work performed for this feasibility study, we have reached the following conclusions regarding the feasibility and reasonableness of constructing the Monte Cresta Drive road extension to the Campbell property, a longer road extension to Station 17+50, and the entire conceptual through road connection.

Station 10+00 to 11+04 (Campbell Road Extension)

1. This portion of the Monte Cresta Drive alignment is suitable for the currently proposed 104-foot-long road extension to the Campbell property.

2. The recommended supplemental geotechnical investigation and preparation of updated geotechnical recommendations for the proposed road extension described in Cotton, Shires & Associates’ September 8, 2005 Supplemental Geotechnical Review letter should be performed. The scope of this recommended supplemental geotechnical study is consistent with local practice and the results of our geologic and geotechnical feasibility study.

Station 11+04 to 17+50 (Campbell Road Extension to Spur Ridge)

1. Significant geologic hazards are present along this 646-foot long section of the roadway, particularly within the three mapped Pdf zones located across or immediately downslope of the road alignment. Six landslides are present on the hillside downslope side of the alignment, and the headscarp of one landslide 376
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crosses into the road alignment. Four landslides are present along the upslope side of the alignment.

2. A geotechnical investigation (or investigations), including subsurface exploration in and between the landslide areas shown on Figures 4 and 5, laboratory testing of materials from the borings, analyses of slope stability, and development of detailed, specific recommendations for road construction, would be required prior to design and construction of this portion of the road. Similar investigations would be required prior to development of individual lots.

3. Design and construction of landslide repairs and retaining walls along both sides of this section of Monte Cresta Drive must consider how and where future access to individual lots along the alignment will be achieved.

4. Proper planning, design, and construction of a road extension from Station 11+04 to 17+50 will be strongly influenced by the development intentions and plans prepared and submitted by individual property owners. The specific construction and mitigation measures required for a road extension along this section of the alignment will also be highly dependent on the lot access and development plans for individual properties along the alignment prepared in the future by others.

Given the current City policy against development in geologically unstable areas, the steep hillsides, and the lack of development occurring along Monte Cresta Drive between Station 11+04 and 17+50, development of Monte Cresta Drive between Station 11+04 and 17+50 is not currently feasible or reasonable.

North of Station 17+50 (North of Spur Ridge)

1. Minor to very large and serious landsliding and mass wasting has occurred on the hillside within this portion of the alignment over a significant period of time. This movement began during the orogenic mountain building processes that formed the hillside region and contributed to the general geomorphology noted on the hillside and along the alignment. Erosion and deep landslides contributed to the formation of the broad canyons and swales on the hillside. More recent, shallower landsliding has accelerated since rough grading of Monte Cresta Drive occurred.

These landslides and areas of mass wasting have caused severe damage and modification of the hillside, the existing roadway, and the through road alignment north of the spur ridge.

2. The hillside in the northern portion of the alignment is being transformed by very volatile and unpredictable surface and subsurface processes. These processes are caused by the steep slopes, uncontrolled surface water runoff, weak surface materials, existing shallow and deep landslides, deleterious bedrock structure, and subsurface seepage. Deleterious bedrock structural conditions consist of variably 377
Mr. Damon Campbell Monte Cresta Drive Through Road Page 20 of 20 ROMIG ENGINEERS, INC.
altered, weathered, pervasively sheared fractures, and bedding and fracture surfaces with adverse dip that in some locations contain altered, laterally continuous in-fills. In our opinion, this erratic developmental disorder does not provide an adequate base for a through road capable of surviving a 50-year service life without experiencing the effects of significant on-going shallow and deep geologic hazards.

3. Based on the results of our feasibility study for the Monte Cresta Drive through road alignment, it is our opinion that, from a geologic and geotechnical engineering viewpoint, design and construction of a safe, relatively maintenancefree through road north of Station 17+50 is not reasonable or feasible, even with design and construction of extensive mitigation measures.

4. Access to many of the individual lots along the portion of the roadway north of Station 17+50 would be very difficult to achieve. In addition, both shallow and deep-seated landslides along both sides of this section of the road alignment may make development of safe, stable building areas on many of the lots economically impractical or impossible to justify.

SUMMARY
Based on the results of the geologic and geotechnical feasibility study described in this report, we have concluded that construction of the proposed 104-foot-long road extension to the Campell property (i.e. from Station 10+00 to 11+04) is reasonable with proper design and implementation of standard mitigation measures.

Given the current City policy against development in geologically unstable areas, the steep hillsides, and the lack of development occurring along Monte Cresta Drive between Station 11+04 and 17+50, development of Monte Cresta Drive between Station 11+04 and 17+50 is not currently feasible or reasonable.

Based on the results of our geologic and geotechnical study, we have concluded that design and construction of the Monte Cresta Drive through road is not reasonable or feasible even with design and implementation of extensive mitigation measures due to the severe geologic and geotechnical constraints in the northern portion of the roadway alignment.
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REFERENCES
Aerial Photographs
Source Imagery Date Scale
PAS* AV-01-01-29/30 6/18/37 1:12,000
PAS AV-9-07 /29/46 7/29/46 1:23,600
PAS AV-170-12-9/10 5/10/55 1:10,000
PAS AV-933-11-8/9 10/28/69 1:12,000
PAS AV-2020-10-9/10 6/19/81 1:12,000
PAS AV-2265-10-8/9 6/6/83 1:12,000
PAS AV-2670-10-8/9 10/15/85 1:12,000
PAS AV-4916-11-8/9 9/7/95 1:12,000
PAS AV-6600-11-8/9 8/16/00 1:12,000
PAS KAV-9010-91-4/5 3/15/05 1:12,000
* PAS = Pacific Aerial Surveys
Publications and Reports
Brabb, E.E., 1972, Preliminary Map of Landslide Deposits in San Mateo County, California, U.S. Geological Survey Miscellaneous Field Studies Map MF-344, scale 1:62,500.

Brabb, E.E., Graymer, R.W., and Jones, D.L., 2000, Geologic Map and Map Database of the Palo Alto 30’ X 60’Quadrangle, California, U.S. Geological Survey Miscellaneous Field Studies Map MF-2332.

Brabb, E.E., and Olson, J.A., 1986, Map Showing Faults and Earthquake Epicenters in San Mateo County, California, U.S. Geological Survey Miscellaneous Investigations Series, Map I-1257F, Scale 1:62,500.

Brabb, E.E., and Pampeyan, E.H., 1972, Preliminary Geologic Map of San Mateo County, California, U.S. Geological Survey Miscellaneous Field Studies Map MF-328, scale 1:62,500.

Brabb, E.E., and Pampeyan, E.H., 1983, Geologic Map of San Mateo County, California, U.S. Geological Survey Map I-1257-A.

Briscoe, Ivester & Bazel, LLP, 2007, Monte Cresta Roadway Improvement Plan (Application ID 2000-1085): Response to April 4, 2006, Staff Report and June 16, 2006 Memorandum.
379
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California Building Standards Commission and International Code Council, 2006, 2007 California Building Code, California Code of Regulations, Title 24, Part 2.

California Department of Conservation, Division of Mines and Geology (DMG), 1994, Fault-Rupture Hazard Zones in California, Special Publication 42.

City of Belmont, 1988, San Juan Hills Area Plan, Adopted as an Amendment to the General Plan by the City Council on March 22, 1988.

City of Belmont, 1988, Ground Movement Potential and Geologic Hazard Policy Map, in San Juan Hills Area Plan, adopted March, 1988.

City of Belmont, 2007, Response to August 16, 2007 Letter from Melanie Tang Regarding the Monte Cresta Roadway Improvement Plan.

Cotton, Shires & Associates, Inc., 2002, Geologic and Geotechnical Review, Aubain, Proposed Roadway and Driveway Entrances, Monte Cresta Drive Extension (APN 043- 160-350).

Earth Mechanics Consulting Engineers, 2000, Geotechnical Investigation, Planned Residence at APN 043-243-110 and 043-243-100, Belmont, California, July 6, 2000, Consultant Report.

Earth Mechanics Consulting Engineers, 2001, Geotechnical Investigation, Planned Monte Cresta Drive Extension, Belmont, California, October 18, 2001, Consultant Report.

Earth Mechanics Consulting Engineers, 2006, Geotechnical Consultation, Proposed Residence at APN 043-243-110 and 043-242-100, Belmont, California, January 12, 2006, Consultant Report.

Leighton and Associates, 1976, Geotechnical Hazard Synthesis Maps of San Mateo County, California, prepared for the San Mateo County Planning Department.

Luzuriaga Taylor, Inc., 2002, Feasibility for Road Improvements along Monte Cresta Drive, Belmont, California, Drawing Nos. EX-1 through EX-4, October 24, 2002.

Luzuriaga Taylor, Inc., 2003, Feasibility for Road Improvements Along Monte Cresta Drive, Belmont Country Club Properties, Subdivision Number 9 & 10, Belmont, California, Drawing Nos. EX-1 through EX-5, September 26, 2003.

Luzuriaga Taylor, Inc., 2004, Monte Cresta Drive Feasibility Study, October 22, 2004 letter indicating required removal of protected trees in order to construct the through road.

Luzuriaga Taylor, Inc., 2005, Proposed Cross Sections, Feasibility Study, Monte Cresta Drive, Belmont, California, Drawing Nos. EX-1, EX-2, and EX-3, November 11, 2005. 380
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Schwartz, D.P., 1994, New Knowledge of Northern California Earthquake Potential, in Proceedings of Seminar on New Developments in Earthquake Ground Motion Estimation and Implications for Engineering Design Practice, Applied Technology Council.

William Cotton and Associates, April 1985, Engineering Geologic Map, San Juan Canyon Study Area, Belmont, California.

William Cotton and Associates, April 1985, Geologic Hazard Analysis of the San Juan Canyon Study Area, Belmont, California.

William Cotton and Associates, April 1985, Ground Movement Potential Map, San Juan Canyon Study Area, Belmont, California.

Working Group on California Earthquake Probabilities (WGCEP), 2003, Earthquake Probabilities in the San Francisco Bay Region, California: 2002 to 2031 – A Summary of Findings, U.S. Geological Survey Circular Open File Report 03-214. ❖ ❖ ❖ ❖ ❖
381
Scale: 1 inch = 2000 feet
Base is United States Geological Survey San Mateo 7.5 Minute Quadrangle, dated 1956, photorevised 1980.

VICINITY MAP FIGURE 1
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
SITE
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Scale: 1 inch = 200 feet
Base is Engineering Geologic Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

VICINITY GEOLOGIC MAP FIGURE 2
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
SITE
LEGEND
Af Artificial fill
Als Active Landslide
KJfs Franciscan Complex Sandstone
sp Serpentinite
Geologic Contact
Bedding Orientation
Fracture
Landslide, arrows indicate
direction of movement
Colluvium
43°
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Scale: 1 inch = 200 feet
Base is Ground Movement Potential Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

GROUND MOVEMENT POTENTIAL MAP FIGURE 3
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
SITE
Pdf
Ps
Pd
LEGEND
Pdf Steep to very steep terrain susceptible to debris flows Ps Relatively unstable material, less than 10 feet deep, susceptible to shallow slope failures
Pd Relatively unstable landslide debris greater than 10 feet in depth
Ms Moving shallow landslides, commonly less than 10 feet thick Geologic Contact
Pdf
Ms
Pdf
Pd
Ps
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Mw • Mass wasi.ig. undefined down$10f)o m()\'001Q0t, 1nclu6BS landslleles.

Qls • L:lndsido; nrrowg, indicate <lireclJon of movetnenl, 'A' l�ic-.1* 3Clive,
....,.
'$' indic:c1tcs shallow Slough« Nlthflow, 'df' lndiwt.(.'$ __
KJf.s • Frandsc.an Complex Sandstone Pdf" • Ste-op to very stoop KJfc • Frandsc.an Complex Chert
sp • Scrpentinitc
/ - •• Goologlc C<wl&.w::l @ . w.o.,..ov,,ne
D A ·L...,.,.. ....... "' / � � • Sll'ike and dip of b6ddif'lg --� ' / • SlrikO � dip of fmcturo
"'-.�•Cut&lope
A__� •Fill£10pe
rf/ ,.,...,.
\., ) • Goo1oQiC Cross So,ction
�O()w$
terrain $1SS08Pti>IO to
Pg. • Relati'vety l.ffl'.l&blO
material, 188& lhon
10feotdeep
SUS08f)t1ble IO
sl\8lc:)'.v aJot)o failures
Pd' • RelahW!ty unstable
landsliclo debtis
grcatonhOO 10 ,ee1
in depth
M$" • Moving W!Jow
lanclS!ldes, oommonty
less than 10 feet
"'""
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385
- Landslide Hazard Zones; outlines of existing landslides, debris flows, shallow sloughs, areas of mass wasting, and Pd zones (William Cotton and Associates, 1985) ENGINEERING GEOLOGIC HAZARD MAP FIGURE 5
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
Note: This landslide hazard map is a conceptual representation of landslides and Pd zones (William Cotton and Associates, 1985) and should not be used for any other purpose.

Base: Figure 4, Romig Engineers, Inc., June 2008
Proposed through
road alignment
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GEOLOGIC CROSS SECTION A-A' FIGURE 6
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
Existing
Residence
KJfs
Qls'A'
Qls'A'
KJfs
Bedding Orientation
(as measured by William
Cotton and Associates, 1985)
KJfs
Monte Cresta Drive
Easement
Scale: 1 inch = 50 feet
Horizontal & Vertical
Refer to Figure 4 for Explanation
200
250
350
450
550
300
400
500
600 600
550
450
350
250
200
300
400
500

ELEVATION IN FEET

ELEVATION IN FEET
A A'
Note: This cross section is a conceptual representation of general geologic relationships and should not be
used for any other purpose.

N20°W N55°W
Mass Wasting
Existing Path
Qls?
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GEOLOGIC CROSS SECTION B-B' FIGURE 7
MONTE CRESTA DRIVE THROUGH ROAD JUNE 2008
BELMONT, CALIFORNIA PROJECT NO. 2092-1
Existing
Residence
Upper Boundary
to Ms zone
(William Cotton and Associates, 1985)
KJfs
Typical Bedding
(Measured)
Typical Fracture Sets KJfs
(William Cotton
and Associates, 1985)
Qls'A'
Qls'A'
Qls'A'?
Existing
Path
Qls'A'?
Qls'A'
KJfs
Existing Ground Surface
Typical
Fracture Sets
(William Cotton and
Associates, 1985) Typical Bedding
(William Cotton and Associates, 1985)
KJfs
Downhill boundary
to Ms zone
Monte Cresta Drive
through road
easement (40 feet)
Upper Boundary to Pdf zone
Note: This cross section is a conceptual representation of general geologic relationships and should not be
used for any other purpose.

Scale: 1 inch = 50 feet
Horizontal & Vertical
Refer to Figure 4 for Explanation
200
250
350
450
550
300
400
500
600 600
550
450
350
250
200
300
400
500

ELEVATION IN FEET

ELEVATION IN FEET
B N5°W B'
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R O M I G E N G I N E E R S, I N C.

GEOTECHNICAL & ENVIRONMENTAL SERVICES
1390 El Camino Real, Second Floor  San Carlos, California 94070  (650) 591-5224  Fax (650) 591-5251 December 3, 2015
3614-1
Mr. Jeff Kraft RE: FEASIBILITY EVALUATION
105 Scenic Drive SINGLE-FAMILY RESIDENCE
Redwood City, California 94062 MONTE CRESTA DRIVE (APN 043-165-180)

BELMONT, CALIFORNIA
Dear Mr. Kraft:

This letter summarizes the results of our geotechnical feasibility evaluation for construction of a single family residence on your property (APN 043-165-180) southwest of the terminus of Monte Cresta Drive in Belmont, California. The approximate location of the property is shown on the attached Vicinity Map, Figure 1.

The scope of our services for this geotechnical feasibility evaluation was presented in our agreement with you dated October 30, 2015. Our work for this feasibility study consisted of: a site reconnaissance; geologic field mapping; review of geologic, geotechnical, and seismic information in our files pertinent to the area of the site; review of Romig Engineers’ geologic and geotechnical feasibility report, dated June 30, 2008, for the Monte Cresta Drive Through Road; review of the preliminary architectural plans for the proposed residence, dated September 24, 2015, prepared by Chris Pardo Design: Elemental Architecture; evaluation of the information described above; and preparation of this feasibility-level report. Subsurface investigation was not performed for this feasibility evaluation.

Based on the favorable results from our feasibility investigation, you have authorized Romig Engineers to perform a design-level geotechnical investigation of the property, including drilling, sampling, and logging of exploratory borings, performing laboratory tests on selected samples of material recovered from the borings, and preparing a geotechnical report to address the proposed construction. The results of our design-level investigation are expected to be available in the next month or so.

Proposed Project
The proposed project consists of constructing a 3,100-square-foot, three-story, split-level residence with a 400-square-foot attached garage on the steeply sloping site. The elevation of the two lower floors will be lower than the ground surface elevation within the adjacent Monte Cresta Drive right-of-way. The residence will be founded on reinforced concrete piers with the majority of the residence structurally supported above the ground surface. Access to the garage on the upper level of the residence will be provided by a pier-supported elevated structural slab.

The location and configuration of the proposed residence are shown on the Site Plan, Figure 2.

Since the current terminus of Monte Cresta Drive does not have adequate space for fire truck turnaround, the proposed project includes construction of a fire truck turnaround within the Monte Cresta Road right-of-way immediately north of the property. 389
Mr. Jeff Kraft Kraft Residence Feasibility Evaluation Page 2 of 7

FINDINGS
Surface Conditions
The subject property is located on a relatively steep slope along the southern side of the Monte Cresta Drive right-of-way adjacent to the current terminus of Monte Cresta Drive.

The ground surface across the majority of the property slopes down to the south at an average gradient that ranges from about 2:1 to 2.7:1 (horizontal:vertical). The lower portion of the slope in the southwestern portion of the property was excavated to a gradient of about 1:1 to 1.3:1 (horizontal:vertical) prior to construction of the residences south of the property.

The majority of the property is covered with a sporadic growth of native grasses and weeds, and a few small to large trees.

A small wedge-shaped fill containing concrete debris is present along the southern side of the Monte Cresta Drive right-of-way along the northern side of the property. What appears to be a thin layer of fill containing concrete debris is also present in the eastern portion of the site, extending downslope from the Monte Cresta Drive right-of-way to approximately the southern property line, as shown on the Preliminary Site Geologic Map, Figure 3. This fill appears to have been in-place for many years since the time of construction of Monte Cresta Drive. A subtle debris flow chute is present west of the southwestern side of the property.

Published geologic maps of the area and aerial photographs do not indicate the presence of landsliding on the subject property. During our recent site reconnaissance and geologic mapping, we did not observe evidence of slope instability on the property, along the debris flow chute, or along the upslope side of the slope excavation on and below the southwestern portion of the property.

Anticipated Subsurface Conditions
Based on our observations on and around the property, the results of our previous geologic and geotechnical investigation for the Monte Cresta Drive Through Road, published geologic maps, interpretation of stereo-paired aerial photographs, and subsurface exploration performed by others along and north of the Monte Cresta Drive right-of-way, we expect the site is underlain by a thin layer of colluvium ranging in thickness from about 1 to 3 feet overlying Franciscan Formation sandstone. The colluvium in the eastern side of the property is overlain by a thin layer of fill with concrete debris, as described previously.

GEOLOGIC SETTING
Regional Geology
As part of this feasibility evaluation, we reviewed our local experience and geologic literature in our files pertinent to the general area. The information reviewed indicates the site is located in an area mapped as Cretaceous and Jurassic-age sandstone (fs) of the Franciscan Complex (Pampeyan, 1994), as shown on the Vicinity Geologic Map, Figure 4.

The Engineering Geologic Map of the San Juan Canyon Study Area (William Cotton and Associates, 1985), which is shown on Figure 5, indicates the site is underlain by Franciscan 390
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Complex sandstone (KJfs). The sandstone unit is described as highly consolidated, cemented, tan to dark gray, thin to thickly bedded, poorly sorted, fine to coarse grained sandstone commonly interlayered with thin sequence of dark siltstone and shale. A fill mass that supports several residences is present within the drainage east of the site. The western lateral margin of this fill is shown underlying the southeastern portion of the subject site.

There are no indicated landslides or debris flows/chutes within or immediately adjacent to the site.

The Ground Movement Potential Map of the San Juan Canyon Study Area (William Cotton and Associates, 1985), a portion of which is shown on Figure 6, categorizes the hazards and materials in the proposed building area as “Ps,” relatively unstable materials susceptible to shallow slope failures. Mapped “Ps” areas are typically considered areas of potentially unstable material, including landslide debris, slope materials, and weak bedrock, commonly less than 10 feet in thickness on gentle to moderately steep slopes.

Based on our site observations and the shallow depth to competent sandstone bedrock across the site, the potential for slope instability to affect the proposed residence and driveway appears to be relatively low.

Site Geology
As part of our feasibility evaluation, we performed a surface reconnaissance consisting of walking the subject site, and traversing the slope and nearby roads and properties, where accessible, to observe surficial field features. Our observations are shown on Figure 3. The lot and the immediate site vicinity are located in a moderately to steeply sloping hillside area. Monte Cresta Drive appears to have been graded primarily by excavating into the hillside, with a thin wedge of fill along the downslope side. Sandstone bedrock was observed on the north side of the road right-of-way and within the excavated cut along the southern downslope side of the site. Sedimentary bedding (strata) were oriented northnorthwest in the Monte Cresta Drive road cut and north-northeast in the cut on the south side of the site, with bedding inclinations of 53 to 66 degrees to the northeast on the north side of Monte Cresta Drive and 81 degrees to the northwest in cut on the south side of the site.

Variably oriented fractures were observed in the exposed upper and lower bedrock exposures. The intervening slope was underlain by colluvium and residual soil. We did not observe indications of springs, seeps, or unusually shallow ground water.

A relatively large fill mass (underlying several residences) is located within the drainage east of the site. Based on air photo interpretation, this fill was placed between 1955 and 1966, probably after 1960, and is presumed to be engineered. The western lateral margin of the fill is located within the eastern side of the site approximately where shown on Figures 3 and 5.

The fill thus increases in thickness from west to east within the site. As described in the Surface Conditions section of this report, relatively thin non-engineered fill is present along the northern side of the property. This fill contains concrete debris and is located along the downslope side of the Monte Cresta Drive right-of-way. Additional fill containing concrete and additional debris mantles the eastern side of the property. It is unlikely that either fill deposit is more than about 4 to 5 feet thick.
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Mr. Jeff Kraft Kraft Residence Feasibility Evaluation Page 4 of 7 During our geologic reconnaissance, we traversed the site and neighboring slopes and did not observe indications of recent slope movement. There were no indications of significant settlement or lateral movement of the paved section of Monte Cresta Drive to the east or within the area underlain by engineered fill.

There do not appear to be any indications of landslides, faults, or other geologic hazards that would significantly affect the proposed residence or fire truck turnaround.

Aerial Photographs
Ten sets of stereo pair aerial photographs were interpreted for this study. The images were flown from 1937 through 2000 and ranged in scale from 1:10,000 to 1:23,600. The images are listed in the References section of this report.

Monte Cresta Drive and much of the surrounding road network, except Alhambra Drive, were present in 1937. The fill currently present east of the site in the adjacent drainage was not present. Monte Cresta Drive was developed with an excavated upslope cut and a wedge fill prism along the downslope side. There were no indications of landslides or flows on or immediately adjacent to the site. The site and the immediate vicinity exhibited a similar appearance in the 1946 and 1955 imagery.

By 1969, the fill within the drainage to the east had been constructed, extending as far as approximately one-third to one-half way across the subject site although thinning to meet the natural ground surface. Monte Cresta Drive had been paved to its approximate current culde-sac, although the cul-de-sac was not present. Alhambra Way was present on a broad excavated bench, with several residences including the immediate downslope residence present. The narrow bench immediately below the site was present. By 1979, the adjacent residence to the east and the cul-de-sac had been constructed. The eastern residence was located on the relatively flat upper area of the fill mass, and the fill slope was located immediately south of the residence. The large fill mass appeared to thin and meet the natural ground essentially as it appeared in the 1969 imagery.

The site was essentially unchanged through the 1980s to 1995. The 1995 imagery indicates the eastern side of the site had been cleared, and possible shallow fill placed on the previous ground surface. The fill did not significantly modify the ground surface appearance and thus is unlikely to be more than a few feet thick. Based on our review of historic Google Earth imagery, the thin fill was probably placed in approximately 1992. The site was essentially unchanged in the 2000 imagery, and based on historic Google Earth imagery, was also unchanged to the present.

In summary, the pre-development ground surface is uneven, as is typical for the vicinity.

There are no indications of landsliding, slumps, or flows on or immediately adjacent to the site. The fill mass east of the site feathers to meet the natural ground surface approximately one-third to one-half way across the site. The fill is likely less than 1 foot in thickness near the center of the site increasing to a maximum estimated thickness of about 5 feet along the eastern property line.
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Faulting and Seismicity
There are no mapped through-going faults within or adjacent to the site and the site is not located within a State of California Earthquake Fault Zone, an area where the potential for fault rupture is considered probable. The closest active fault is the San Andreas fault, which is located approximately 1.7 miles southwest of the property. Thus, the likelihood of surface rupture occurring from active faulting at the site is low.

The San Francisco Bay Area is an active seismic region. Earthquakes in the region result from strain energy constantly accumulating because of the northwestward movement of the Pacific Plate relative to the North American Plate. On average about 1.6-inches of movement occur per year. Historically, the Bay Area has experienced large, destructive earthquakes in 1838, 1868, 1906, and 1989. The faults considered most likely to produce large earthquakes in the area include the San Andreas, San Gregorio, Hayward, and Calaveras faults. The San Gregorio fault is located approximately 9.5 miles southwest of the site. The Hayward and Calaveras faults are located approximately 17 and 24 miles northeast of the site, respectively. These faults and significant earthquakes that have been documented in the Bay Area are listed on Table 1 below.

In the future, the subject property will undoubtedly experience severe ground shaking during moderate and large magnitude earthquakes produced along the San Andreas fault or other active Bay Area fault zones. The Working Group on California Earthquake Probabilities, a panel of experts that are periodically convened to estimate the likelihood of future earthquakes based on the latest science and ground motion prediction modeling, concluded there is a 72 percent chance for at least one earthquake of Magnitude 6.7 or larger in the Bay Area before 2045. The Hayward fault has the highest likelihood of producing an earthquake greater than or equal to magnitude 6.7 in the Bay Area, estimated at 14 percent, while the likelihood on the San Andreas and Calaveras faults is estimated at approximately 6 and 7 percent, respectively (Working Group, 2015).

Table 1. Earthquake Magnitudes and Historical Earthquakes Belmont, California
Maximum Historical Estimated
Fault Magnitude (Mw) Earthquakes Magnitude
San Andreas 7.9 1989 Loma Prieta 6.9
1906 San Francisco 7.9
1865 N. of 1989 Loma Prieta Earthquake 6.5
1838 San Francisco-Peninsula Segment 6.8
1836 East of Monterey 6.5
Hayward 7.1 1868 Hayward 6.8
1858 Hayward 6.8
Calaveras 6.8 1984 Morgan Hill 6.2
1911 Morgan Hill 6.2
1897 Gilroy 6.3
San Gregorio 7.3 1926 Monterey Bay 6.1
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CONCLUSIONS AND PRELIMINARY RECOMMENDATUIONS
Based on the results of our feasibility evaluation, we have concluded that the site is suitable for construction of the proposed single-family residence. The recommendations in our upcoming design-level geotechnical report should be followed during design and construction of the residence, site improvements, and fire truck turnaround.

The primary geologic and geotechnical concerns for construction of the proposed singlefamily residence on the subject property are: 1) the presence of the existing undocumented, wedge-shaped fill along the southern side of the Monte Cresta Drive right-of-way; 2) the presence of the thin undocumented fill in the eastern portion of the site; 3) the steepness of the site for construction of foundation piers; 4) the need to dispose of roof water and storm water runoff on the site (rather than into an existing storm drain system); and 5) the probability of severe ground shaking at the site during a major earthquake in the area.

Based on the geologic and geotechnical work we have performed to date, we have developed the following conclusions and preliminary recommendations regarding design and construction of the proposed single-family residence on the subject site. In our opinion, these minimum guidelines will need to be followed during design and construction in order for the City of Belmont to grant grading and building permits for the proposed residence and fire truck turnaround.

1. The existing undocumented fill in the Monte Cresta Drive right-of-way and along the northern side of the site should be removed and recompacted with observation and testing during earthwork construction by our staff. Remedial grading of the existing fill will need to extend beyond the edge of the proposed fire truck turnaround. The fill should be keyed and benched into competent bedrock below any fill and native soil.

2. The existing thin fill in the eastern portion of the site appears to have been in-place without signs of instability since the 1960s. Since no grading or ground-supported structures are proposed for the eastern side of the site, and the proposed residence will be supported on reinforced concrete piers, the existing fill may remain in-place without presenting a risk to the proposed residence or adjacent residences. Construction of the reinforced concrete piers is expected to increase the stability of the existing fill.

3. Due to the steepness of the site, the proposed residence and driveway deck should be supported on reinforced concrete piers at least 16 inches in diameter embedded in competent sandstone bedrock. The minimum required depth of the piers will depend on the depth to bedrock and lateral loads from the proposed residence. At the present time, we anticipate the minimum required depth of the piers will be at least 15 feet and at least 12 feet into competent bedrock. Difficult to very difficult drilling conditions should be anticipated to achieve the required depth of pier embedment into the Franciscan Complex bedrock.

4. Retaining walls along the downslope side of the fire truck turnaround and around the upslope side of the lower levels of the residence should also be supported on reinforced concrete piers.
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5. Storm water runoff from roof downspouts and hardscape surfaces will need to be collected and disposed of on-site by means of a suitable storm water detention system with metered release to a level spreader at a suitable location. Storm water should not be disposed of in the eastern portion of the site where fill is present. Constructing a row of stitch piers along the downslope side of a level spreader would be advisable.

The conclusions and preliminary geotechnical recommendations summarized above will need to be confirmed during our design-level geotechnical investigation of the site.

LIMITATIONS
We make no warranty, expressed or implied, for the services we perform for this project.

Our services are performed in accordance with the geologic and geotechnical engineering principles generally accepted at this time and location.

Please call if you have questions or comments about site conditions or the findings, conclusions, and preliminary recommendations from the feasibility evaluation summarized above.

Very truly yours,
ROMIG ENGINEERS, INC.

Richard G. Woodard, P.E., G.E. David F. Hoexter, P.G, C.E.G.

Expires 11/30/17
Attachments:

REFERENCES
Figure 1 - Vicinity Map
Figure 2 - Site Plan
Figure 3 - Preliminary Site Geologic Map
Figure 4 - Vicinity Geologic Map
Figure 5 - San Juan Canyon Engineering Geologic Map
Figure 6 - San Juan Canyon Ground Movement Potential Map Copies: Addressee (5)
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REFERENCES
Aerial Photographs
United States Geologic Survey Library, Menlo Park, California (USGS); USDA (United States Department of Agriculture Adjustment Administration (CIV series); WAC Corporation, Eugene, Oregon (WAC); and Pacific Aerial Surveys, Oakland, California (PAS): black and white vertical stereo pairs, except as noted.

Source Imagery Date Scale
PAS AV-01-01-30/31 6/18/37 1:12,000
PAS AV-9-16-9/10 7/29/46 1:23,600
PAS AV-170-12-09/10 5/10/55 1:10,000
PAS AV-933-11-08/09 10/28/69 1:12,000
PAS AV-1705-10-09/10 5/30/79 1:12,000
PAS AV-2020-10-09/10 6/19/81 1:12,000
PAS AV-2265-10-08-09 6/6/83 1:12,000
PAS AV-2670-10-8/9 10/15/85 1:12,000
PAS AV-4916-11-8/9 9/7/95 1:12,000
PAS SMT-AV-6600-11-8/9 8/16/00 1:12,000
Publications and Reports
Brabb, E.E., Graymer, R.W., and Jones, D.L., 1998, Geology of the Onshore Part of San Mateo County, California U.S. Geological Open-File 98-137.

Brabb, E.E., and Pampeyan, E.H., 1983, Geologic Map of San Mateo County, California, U.S. Geological Survey Map I-1257-A.

California Department of Conservation, Division of Mines and Geology (DIG), 1994, FaultRupture Hazard Zones in California, Special Publication 42.

City of Belmont, 1988, Ground Movement Potential and Geologic Hazard Policy Map, in San Juan Hills Area Plan, adopted March, 1988.

Pampeyan, E.H, 1981, Geology and Former Shoreline Features of the San Mateo 7.5 Minute Quadrangle, San Mateo County, California, USGS Open-File Report 81-839, Scale 1:24,000.

Pampeyan, E.H., 1994, Geologic Map of the Montara Mountain and San Mateo 7-1/2' Quadrangles, San Mateo County, California, USGS Miscellaneous Investigations Series Map I-2390, Scale 1:24,000.
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Romig Engineers, Inc, 2008, Geologic and Geotechnical Engineering Feasibility Study, Monte Cresta Drive Through Road, Belmont, California, report dated June 30, 2008.

Romig Engineers, Inc., 2013, Geotechnical Report, Campbell Residence, Monte Cresta Drive, Belmont, California, report dated May 31, 2013.

William Cotton, W. & Associates, April 1985, Engineering Geologic Map, San Juan Canyon Study Area, Belmont, California, Scale 1:2,400.

William Cotton and Associates, April 1985, Geologic Hazard Analysis of the San Juan Canyon Study Area, Belmont, California.

William Cotton and Associates, April 1985, Ground Movement Potential and Geologic Hazard Policy Map, San Juan Canyon Study Area, Belmont, California, Scale 1:2,400.

Working Group on California Earthquake Probabilities (WGCEP), 2015, Long-Term TimeDependent Probabilities for the Third Uniform California Earthquake Rupture Forecast, Version 3 (UCERF 3), U.S. Geological Survey Open File Report 2013-1165.    
397
Insert map here and add line around picture - size 1 in black Scale: 1 inch = 2000 feet
Base is United States Geological Survey San Mateo 7.5 Minute Quadrangle, dated 1997.

VICINITY MAP FIGURE 1
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1
SITE
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LEGEND
Approximate Scale: 1 inch = 30 feet.

Base is Site Plan prepared by Triad/Homes Associates, dated November 10, 2015.

SITE PLAN FIGURE 2
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1

MONTE CRESTA
DRIVE

PROPOSED

THREE-STORY

RESIDENCE

PROPOSED

DRIVEWAY
RAMP

PROPOSED

FIRE TRUCK

TURN-AROUND
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LEGEND
Approximate Scale: 1 inch = 30 feet.

Base is Survey prepared by Triad/Homes Associates, dated November 10, 2015.

PRELIMINARY SITE GEOLOGIC MAP FIGURE 3
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1

MAP LEGEND
Qaf-s Shallow fill overlying lateral margin of ca. 1960 fill mass.

Qafr "Wedge" fill supporting road.

Qaf-d ca. 1960 fill mass.

KJfs Franciscan Assemblage Sandstone.

Strike and dip of bedding.

Bedrock outcrop.

Excavated cut.
81 X
Qafr
Qaf-s
Qaf-d
KJfs
X
X X
X
X
X
X
X
X
81 X
X X
X
X
66 X
X X X
X
KJfs
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Scale: 1 inch = 2000 feet
Base is Geologic Map of the Montara Mountain and San Mateo 7.5 Minute Quadrangles, San Mateo County, California, (Pampeyan, 1994).

VICINITY GEOLOGIC MAP FIGURE 4
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1
SITE

MAP LEGEND
Qsr Slope wash, ravine fill, and colluvium (Holocene)
Qf Artificial fill (Holocene)
fs Sandstone (Cretaceous and Jurassic)
fg Greenstone (Cretaceous and Jurassic)
fsr Sheared rock (Cretaceous and Jurassic)
sp Serpentinite (Cretaceous and Jurassic)
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Scale: 1 inch = 200 feet
Base is Engineering Geologic Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

SAN JUAN CANYON ENGINEERING GEOLOGIC MAP FIGURE 5
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1
LEGEND
Af Artificial fill
Als Active Landslide
KJfs Franciscan Complex Sandstone
sp Serpentinite
Geologic Contact
Bedding Orientation
Fracture
Landslide, arrows indicate
direction of movement
Colluvium
43°
SITE
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Scale: 1 inch = 200 feet
Base is Ground Movement Potential Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

SAN JUAN CANYON GROUND MOVEMENT POTENTIAL MAP FIGURE 6
KRAFT RESIDENCE DECEMBER 2015
BELMONT, CALIFORNIA PROJECT NO. 3614-1

MAP LEGEND
Pdf Steep to very steep terrain susceptible to debris flows.

Ps Relatively unstable material, less than 10 feet deep susceptible to shallow slope failures.

Pd Relatively unstable landslide debris greater than 10 feet in depth.

Pfs Potential failure within large areas of engineered fill susceptible to settlement, landsliding, and debris flow.

Sbr Level to moderately sloping ground underlain by bedrock within several feet of the ground surface. Soil cover may be subject to shallow sliding, soil creep, or settlement.

Ms Moving shallow landslides, commonly less than 10 feet thick.

SITE
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I
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ROMIG ENG I NEE RS, INC.

GEOTECHNICAL & ENVIRONMENTAL SERVICES
Mr. Jeff Kraft
105 Scenic Drive
Redwood City, California 94062
Dear Mr. Kraft:

January 29, 2016
3614-1
RE: GEOTECHNICAL INVESTIGATION

KRAFT RESIDENCE

MONTE CRESTA DRIVE
(APN 043-165-180)

BELMONT, CALIFORNIA
As requested, we have performed a geotechnical investigation for the proposed residence on your property (APN 043-165-180) southwest of the terminus of Monte Cresta Drive in Belmont, California. The accompanying report summarizes the results of our subsurface exploration, laboratory testing, and engineering analysis, and presents our geotechnical recommendations for the proposed residence.

We refer you to the text of our report for specific recommendations.

Thank you for the opportunity to work with you on this project. Please call if you have questions or comments about site conditions or the findings and recommendations from our geotechnical investigation for your proposed residence.

Copies: Addressee (4)
Chris Pardo Design: Elemental Architecture (via email)
Attn: Mr. Steven Turley
ASUL (via email)
Attn: Mr. Tim Russell
David Thomas Engineering, A.P .C. (via email)
Attn: Mr. David Thomas
BKF Engineers (via email)
Attn: Mr. Isaac Kontorovsky
1390 El Camino Real, Second Floor • San Carlos, California 94070 • (650) 591-5224 • Fax (650) 591-5251 404

GEOTECHNICAL INVESTIGATION

KRAFT RESIDENCE
MONTE CRESTA DRIVE (APN 043-165-180)

BELMONT, CALIFORNIA
PREPARED FOR:

MR. JEFF KRAFT
105 SCENIC DRIVE
REDWOOD CITY, CALIFORNIA 94062
PREPARED BY:

ROMIG ENGINEERS, INC.
1390 EL CAMINO REAL, SECOND FLOOR
SAN CARLOS, CALIFORNIA 94070
JANUARY 2016
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Letter of transmittal
Cover Page

TABLE OF CONTENTS

TABLE OF CONTENTS
Page No.

IN"TRODUCTION .......................................................................................................... l Project Description ................................................................................................ 1 Scope ofWork ....................................................................................................... l Limitations ............................................................................................................. 2 SUBSURFACE EXPLORATION AND SITE RECONNAISSANCE ......................... 3 Surface Conditions ................................................................................................ 3 Subsurface Conditions ........................................................................................... 3 Ground Water ........................................................................................................ 4 GEOLOGIC SETIING .................................................................................................. 4 Regional Geology .................................................................................................. 4 Site Geology .......................................................................................................... 5 Aerial Photographs ................................................................................................ 6 Faulting and Seismicity ......................................................................................... 7 Table 1. Earthquake Magnitudes and Historical Earthquakes ..................... 8 Earthquake Design Parmneters .............................................................................. 8 Geologic Hazards .................................................................................................. 8 CONCLUSIONS .......................................................................................................... 10 FOUNDATIONS ......................................................................................................... 11 Reinforced Concrete Piers ................................................................................... 11 Lateral Loads ....................................................................................................... 12 Settlement ............................................................................................................ 12 RETAININ"GWALLS ................................................................................................. 12 SLABS-ON-GRADE ................................................................................................... 14 General Slab Considerations ............................................................................... 14 Exterior Flatwork ................................................................................................. 14 Interior Slabs ........................................................................................................ 15 PAVEMENT FOR FIRE TRUCK TURNAROUND .................................................. 15 EARTHWORK ............................................................................................................ 16 Clearing and Sub grade Preparation ..................................................................... 16 Material for Fill ................................................................................................... 16 Compaction .......................................................................................................... 17 Table 2. Compaction Recommendations ................................................... 17 Temporary Slopes and Excavations ..................................................................... 17 Finished Slopes .................................................................................................... 18 Surface Drainage ......................................... . ........................................................ 18 FUTURE SERVICES .................................................................................................. 18 Plan Review ......................................................................................................... 18 Construction Observation and Testing ................................................................ 19 ROMIG ENGINEERS, INC.
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REFERENCES
FIGURE 1 - VICINITY MAP
FIGURE 2 - SITE PLAN

TABLE OF CONTENTS
(Continued)
FIGURE 3 - SITE GEOLOGIC MAP
FIGURE 4 - VICINITY GEOLOGIC MAP
FIGURE 5 - SAN JUAN CANYON ENGINEERING GEOLOGIC MAP
FIGURE 6 - SAN JUAN CANYON GROUND MOVEMENT POTENTIAL MAP

APPENDIX A - FIELD INVESTIGATION
Figure A-1 - Key to Exploratory Boring Logs
Figure A-2 - Key to Bedrock Descriptions
Exploratory Boring Logs EB-1 and EB-2

APPENDIX B - SUMMARY OF LABO RA TORY TESTS
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INTRODUCTION

GEOTECHNICAL INVESTIGATION
FOR

KRAFT RESIDENCE

MONTE CRESTA DRIVE
(APN 043-165-180)

BELMONT, CALIFORNIA
This report presents the results of our geotechnical investigation for the single family residence proposed for construction on the Kraft property (APN 043-165-180) southwest of the terminus of Monte Cresta Drive in Belmont, California. The location of the site is shown on the Vicinity Map, Figure 1. The purpose of this investigation was to evaluate subsurface conditions at the site and to provide geotechnical recommendations for the proposed residence and associated site improvements. The results of our Geotechnical Feasibility Evaluation of the site were presented in a report dated December 3, 2015.

Project Description
The project consists of constructing a 3,100-square-foot, three-story, split-level residence with a 400-square-foot attached garage on the steeply sloping site. The finished floor elevation of the two lower floors will be lower than the ground surface in the adjacent Monte Cresta Drive right-of-way. The residence will be founded on reinforced concrete piers with the majority of the residence structurally supported above the ground surface.

Access to the garage on the upper level of the residence will be provided by a piersupported elevated structural slab.

Since the current terminus of Monte Cresta Drive does not have adequate space for fire truck turnaround, the proposed project includes construction of a fire truck turnaround within the Monte Cresta Road right-of-way immediately north of the property.

Scope of Work
The scope of our geotechnical work for the proposed residence is summarized in our agreement with Mr. Jeff Kraft, dated October 30, 2015. In order to complete our geotechnical investigation of the site, we performed the following work. • Review of geologic, geotechnical, and seismic conditions in the vicinity of the site, including information in our Geologic and Geotechnical Engineering Feasibility Study Report for the Monte Cresta Drive Through Road, dated June 30, 2008.

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• Reconnaissance of the site and the surrounding area by our project geologist and project engineers.
• Review and interpretation of stereo-pair aerial photographs of the site. • Subsurface exploration consisting of drilling, sampling, and logging two exploratory borings within the Monte Cresta Drive right-of-way at the crest of the steep slope along the north side of the property.
• Laboratory testing of selected samples to aid in soil classification and to help evaluate the engineering properties of the soil and bedrock at the site. • Engineering analysis and evaluation of the field and laboratory test data to develop earthwork guidelines and foundation design criteria for the project. • Preparation of this report presenting our findings and geotechnical recommendations for the proposed residence and associated site improvements.

Limitations
This report was prepared for the exclusive use of Mr. Jeff Kraft for specific application to developing geotechnical design criteria for the proposed single-family residence on the property (APN 043-165-180) southwest of the terminus of .Monte Cresta Drive in Belmont, California. We make no warranty, expressed or implied, for the services we perform for this project. Our services are performed in accordance with geotechnical engineering principles generally accepted at this time and location. This report was prepared to provide engineering opinions and recommendations only. In the event there are any changes in the nature, design, or location of the project, or if any future improvements are planned, the conclusions and recommendations presented in this report should not be considered valid unless: 1) the changes are reviewed by us, and; 2) the conclusions and recommendations presented in this report are modified or verified in writing.

The analysis, conclusions, and recommendations presented in this report are based on site conditions as they existed at the time of our investigation; the currently proposed improvements; review of readily available reports relevant to the site conditions; and laboratory test results. In addition, it should be recognized that certain limitations are inherent in the evaluation of subsurface conditions, and that certain conditions may not be detected during an investigation of this type. Changes in the information or data gained from any of these sources could result in changes in our conclusions or recommendations.

If such changes occur, we should be advised so that we can review our report in light of those changes.

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SUBSURFACE EXPLORATION AND SITE RECONNAISSANCE
Reconnaissance of the site was performed by our project geologist and engineers on several occasions in November and December 2015. Subsurface exploration was performed on December 23, 2015 using a track-mounted drill rig equipped with 8-inch hollow stem augers and an automatic trip hammer. Two exploratory borings were advanced to sampler refusal conditions in bedrock at a depth of 10.2 feet at the approximate locations shown on the Site Plan, Figure 2. The boring logs and the results of our laboratory tests are attached in Appendices A and B, respectively.

Surface Conditions
The subject property is located on a relatively steep slope along the southern side of the Monte Cresta Drive right-of-way adjacent to the current terminus of Monte Cresta Drive.

The ground surface across the majority of the property slopes down to the south at an average gradient that ranges from about 2:1 to 2.7:1 (horizontal:vertical). The lower portion of the slope in the southwestern portion of the property was excavated to a gradient of about 1: 1 to 1.3: 1 (horizontal:vertical) prior to construction of the residences south of the property. The majority of the property is covered with a sporadic growth of native grasses and weeds, and a few small to large trees.

A small wedge-shaped fill containing rock fragments, asphalt concrete, and concrete debris is present along the southern side of the Monte Cresta Drive right-of-way along the northern side of the property. What appears to be a thin wedge-shaped layer of fill containing concrete debris is also present in the eastern portion of the site, extending downslope from the Monte Cresta Drive right-of-way to approximately the southern property line, as shown on the Site Geologic Map, Figure 3. This fill appears to have been in-place for many years since the time of construction of Monte Cresta Drive. A subtle debris flow chute is present west of the southwestern side of the property.

Published geologic maps of the area and aerial photographs do not indicate the presence of landsliding on the subject property. During our site reconnaissance and geologic mapping, we did not observe evidence of slope instability on the property, along the debris flow chute, or along the upslope side of the slope excavation on and below the southwestern portion of the property.

Subsurface Conditions
At the location of Boring EB-1, which was advanced immediately west of the terminus of Monte Cresta Drive, we encountered about 4.5 feet of undocumented fill consisting of stiff to very stiff, sandy lean clay with gravel. Large rock and concrete fragments, and asphalt concrete debris, were present within this fill. The fill was underlain by about 1.5 feet of dense, silty sand over severely weathered sandstone bedrock of the Franciscan ROMIG ENGINEERS, INC.
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Complex to a depth of about 10.2 feet, the maximum depth of our exploration. Sampler refusal conditions ( 50 blows for 6 inches or less of sampler advance) occurred in the sandstone and drilling became more difficult with depth.

At the location of Boring EB-2, which was advanced in the northwest portion of the proposed fire truck turnaround, we encountered about 2.5 feet of medium dense to dense, silty sand underlain by severely weathered sandstone bedrock of the Franciscan Complex to a depth of about 10.2 feet, the maximum depth of our exploration. Sampler refusal conditions occurred in the sandstone and drilling became more difficult with depth.

The near-surface native soils encountered in our borings were composed of silty sand with low plasticity fines and were judged to have a relatively low potential for expansion.

Ground Water
Ground water was not encountered in our borings during drilling and sampling. Since the borings were backfilled with grout immediately after sampling was completed, sufficient time may not have been allowed for ground water to seep into the bore holes. Please be cautioned that fluctuations in the level of ground water can occur due to variations in rainfall, landscaping watering on the property and upslope, surface and subsurface drainage patterns, and other factors. It is likely that perched ground water conditions develop in the surface soils and near the surface of the bedrock during and after significant rainfall.

GEOLOGIC SETTING
Regional Geology
As part of our investigation, we reviewed our local experience and geologic literature in our files pertinent to the general area. The information reviewed indicates the site is located in an area mapped as Cretaceous and Jurassic-age sandstone (fs) of the Franciscan Complex (Pampeyan, 1994), as shown on the Vicinity Geologic Map, Figure 4. The Engineering Geologic Map of the San Juan Canyon Study Area (William Cotton and Associates, 1985), which is shown on Figure 5, indicates the site is underlain by Franciscan Complex sandstone (KJfs). The sandstone unit is described as highly consolidated, cemented, tan to dark gray, thin to thickly bedded, poorly sorted, fine to coarse grained sandstone commonly interlayered with thin sequence of dark siltstone and shale. A fill mass that supports several residences is present within the drainage east of the site. The western lateral margin of this fill is shown underlying the southeastern portion of the subject site. There are no indicated landslides or debris flows/chutes within or immediately adjacent to the site.

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The Ground Movement Potential Map of the San Juan Canyon Study Area (William Cotton and Associates, 1985), a portion of which is shown on Figure 6, categorizes the hazards and materials in the proposed building area as "Ps," relatively unstable materials susceptible to shallow slope failures. Mapped "Ps" areas are t} pically considered areas of potentially unstable material, including landslide debris, slope materials, and weak bedrock, commonly less than 10 feet in thickness on gentle to moderately steep slopes.

Based on our site observations and the shallow depth to competent sandstone bedrock across the site, the potential for slope instability to affect the proposed residence and driveway appears to be relatively low.

Site Geology
As part of our investigation, we performed a surface reconnaissance consisting of walking the subject site, and traversing the slope and nearby roads and properties, where accessible, to observe surficial field features. Our observations are shown on Figure 3.

The lot and the immediate site vicinity are located in a moderately to steeply sloping hillside area. Monte Cresta Drive appears to have been graded primarily by excavating into the hillside and placing a thin wedge of fill along the downslope side.

Sandstone bedrock was observed on the north side of the road right-of-way and within the excavated cut along the southern downslope side of the site. Sedimentary bedding (strata) were oriented north-northwest in the Monte Cresta Drive road cut and northnortheast in the cut on the south side of the site, with bedding inclinations of 53 to 66 degrees to the northeast on the north side of Monte Cresta Drive and 81 degrees to the northwest in cut on the south side of the site. Variably oriented fractures were observed in the exposed upper and lower bedrock exposures. The intervening slope was underlain by colluvium and residual soil. We did not observe indications of springs, seeps, or unusually shallow ground water.

A relatively large fill mass underlying several residences is located within the drainage east of the site. Based on air photo interpretation, this fill was placed between 1955 and 1966, probably after 1960, and is presumed to be engineered. The western lateral margin of the fill is located within the eastern side of the subject property approximately where shown on Figures 3 and 5. The fill increases in thickness from west to east within the site and, based on topography, is estimated to have a maximum thickness of about 5 feet along the eastern side of the subject property. As described in the Surface Conditions section of this report, relatively thin non-engineered fill is present along the northern side of the property. This fill contains concrete fragments and asphalt concrete debris and is located along the downslope side of the Monte Cresta Drive right-of-way.

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During our geologic reconnaissance, we traversed the site and neighboring slopes and did not observe indications of recent slope movement. There were no indications of significant settlement or lateral movement of the paved section of Monte Cresta Drive to the east or within the area underlain by engineered fill. There do not appear to be any indications of landslides, faults, or other geologic hazards that would significantly affect the proposed residence or fire truck turnaround.

Aerial Photographs
Ten sets of stereo pair aerial photographs were interpreted for our study. The images were flown from 1937 through 2000 and ranged in scale from 1:10,000 to 1:23,600. The images are listed in the References section of this report.

Monte Cresta Drive and much of the surrounding road network, except Alhambra Drive, were present in 1937. The fill currently present east of the site in the adjacent drainage was not present. Monte Cresta Drive was developed with an excavated upslope cut and a wedge fill prism along the downslope side. There were no indications of landslides or flows on or immediately adjacent to the site. The site and the immediate vicinity exhibited a similar appearance in the 1946 and 1955 imagery.

By 1969, the fill within the drainage to the east had been constructed, extending as far as approximately one-third to one-halfway across the subject site although thinning to meet the natural ground surface. Monte Cresta Drive had been paved to its approximate current cul-de-sac, although the cul-de-sac was not present. Alhambra Way was present on a broad excavated bench, with several residences including the immediate downslope residence present. The narrow bench immediately below the site was present. By 1979, the adjacent residence to the east and the cul-de-sac had been constructed. The eastern residence was located on the relatively flat upper area of the fill mass, and the fill slope was located immediately south of the residence. The large fill mass appeared to thin and meet the natural ground essentially as it appeared in the 1969 imagery.

The area of the site was essentially unchanged through the 1980s to 1995. The 1995 imagery indicates the eastern side of the site had been cleared, and possible shallow fill placed on the previous ground surface. The fill did not significantly modify the ground surface appearance and thus is unlikely to be more than a foot or two thick. Based on our review of historic Google Earth imagery, the thin fill was probably placed in approximately 1992. The site was essentially unchanged in the 2000 imagery, and based on historic Google Earth imagery, was also unchanged to the present.

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In summary, the pre-development ground surface is uneven, as is typical for the vicinity.

There are no indications of landsliding, slumps, or flows on or immediately adjacent to the site. The fill mass east of the site feathers to meet the natural ground surface approximately one-third to one-half way across the site. The fill is likely less than about 1 foot thick near the center of the property increasing to a maximum estimated thickness of about 5 feet along the eastern property line.

Faulting and Seismicity
There are no mapped through-going faults within or adjacent to the site and the site is not located within a State of California Earthquake Fault Zone, an area where the potential for fault rupture is considered probable. The closest active fault is the San Andreas fault, which is located approximately 1. 7 miles southwest of the property. Thus, the likelihood of surface rupture occurring from active faulting at the site is low.

The San Francisco Bay Area is an active seismic region. Earthquakes in the region result from strain energy constantly accumulating because of the northwestward movement of the Pacific Plate relative to the North American Plate. On average about 1.6-inches of movement occur per year. Historically, the Bay Area has experienced large, destructive earthquakes in 1838, 1868, 1906, and 1989.

The faults considered most likely to produce large earthquakes in the area include the San Andreas, San Gregorio, Hayward, and Calaveras faults. The San Gregorio fault is located approximately 9.5 miles southwest of the site. The Hayward and Calaveras faults are located approximately 17 and 24 miles northeast of the site, respectively. These faults and significant earthquakes that have been documented in the Bay Area are listed on Table 1 below.

In the future, the subject property will undoubtedly experience severe ground shaking during moderate and large magnitude earthquakes produced along the San Andreas fault or other active Bay Area fault zones. The Working Group on California Earthquake Probabilities, a panel of experts that are periodically convened to estimate the likelihood of future earthquakes based on the latest science and ground motion prediction modeling, concluded there is a 72 percent chance for at least one earthquake of Magnitude 6.7 or larger in the Bay Area before 2045. The Hayward fault has the highest likelihood of producing an earthquake greater than or equal to magnitude 6.7 in the Bay Area, estimated at 14 percent, while the likelihood on the San Andreas and Calaveras faults is estimated at approximately 6 and 7 percent, respectively (Working Group, 2015).

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Table 1. Earthquake Magnitudes and Historical Earthquakes Kraft Residence
Maximum
Fault Magnitude (Mw)
San Andreas 7.9
Hayward 7.1
Calaveras 6.8
San Gregorio 7.3
Earthquake Design Parameters
Belmont, California
Historical
Earthquakes
Estimated
Magnitude
1989 Loma Prieta 6.9
1906 San Francisco 7 .9
1865 N. of 1989 Loma Prieta Earthquake 6.5
1838 San Francisco-Peninsula Segment 6.8
1836 East of Monterey 6.5
1868 Hayward 6.8
1858 Hayward 6.8
1984 Morgan Hill
1911 Morgan Hill
1897 Gilroy
1926 Monterey Bay

6.2 6.2

6.3 6.1
The State of California currently requires that all buildings be designed in accordance with the seismic design provisions presented in the 2013 California Building Code and in ASCE 7, "Minimum Design Loads for Buildings and Other Structures." Based on site geologic conditions and on information from our subsurface exploration at the site, the site may be classified as Site Class C, very dense soil and soft rock, in accordance with Chapter 20 of ASCE 7-10. Spectral acceleration response parameters Ss and S1, and site coefficients Fa and Fv, may be taken directly from the U.S.G.S. website based on the latitude and longitude of the proposed structure. For the site latitude (3 7 .5180 degrees) and longitude (-122.3116 degrees) and Site Class C, Fa = 1.0, Fv = 1.3, SDs = 1.486g, and SDl = 0.923g.

Geologic Hazards
As part of our investigation, we reviewed the potential for geologic hazards to impact the site and the proposed residence considering the geologic setting and the soil and bedrock encountered during our investigation. The results of our review are presented below. • Fault Rupture - The site is not located in a State of California Earthquake Fault Zone or area where fault rupture is considered likely. Therefore, active faults are not believed to exist beneath the site and the potential for fault rupture to occur at the site is considered low.

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• Ground Shaking - The site is located in an active seismic area. Moderate to large earthquakes are probable along several active faults in the greater Bay Area over a 30 to 50 year design life. Strong ground shaking should therefore be expected several times during the design life of the proposed residence, as is typical for sites throughout the Bay Area. The proposed residence and retaining walls for the fire truck turnaround should be designed and constructed in accordance with current earthquake resistance standards.
• Liquefaction - Liquefaction occurs when saturated, sandy soils lose strength during earthquake shaking. Ground settlement often accompanies liquefaction.

Soils most susceptible to liquefaction are saturated, loose, silty sands, sandy silts, and uniformly graded sands. Since relatively shallow bedrock was encountered in our borings and observed across the site, and no saturated loose silty sands and other types of soil prone to liquefaction were encountered above the bedrock, the likelihood ofliquefaction occurring at the site is low. • Differential Compaction - Differential compaction can occur during moderate and large earthquakes when soft or loose, natural or fill soils are densified and settle, often unevenly across a site. As discussed previously, about 4.5 feet of undocumented fill is present near the crest of the steep slope at the location of Boring EB-1 and appears to be present along the southern side of the Monte Cresta Drive right-of-way. Due to the variable nature of this fill material, it is difficult to estimate the amount of dynamic settlement that could occur along the downslope side of the proposed fire truck turnaround. In our opinion, differential settlement of the existing fill in the Monte Cresta Drive right-of-way is probable unless the fill is excavated and recompacted as recommended in this report. • Slope Stability - During our geologic review and geologic reconnaissance of the subject property, we did not find evidence of landsliding, instability, or erosion of the thin layer of native soil over bedrock or the fill that was placed in the eastern portion of the property in the 1960s. The currently proposed project does not include placement of unsupported fill downslope of the fire truck turnaround or construction of surface improvements other than the residence on the slope south of the fire truck turnaround.

Based on this information, we have concluded that the risk of damage to the proposed pier-supported residence from slope instability is low, provided that:
storm water runoff is properly controlled and discharged on and around the property; existing fill in the area for the proposed fire truck turnaround is removed and recompacted; proposed fill around the southern side of the fire truck turnaround is retained by a properly designed pier-supported retaining wall; and foundation piers for the proposed residence are designed and constructed to account for loads from the proposed residence and potential creep forces from the existing fill in the eastern portion of the property.

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CONCLUSIONS
From the geotechnical viewpoint, the site is suitable for the proposed residence, driveway deck, and fire truck turnaround, provided the recommendations presented in this report are followed during design and construction. Specific recommendations for the project are presented in the following sections of this report.

The primary geologic and geotechnical concerns for construction of the proposed residence and fire truck turnaround are: 1) the presence of the existing wedge-shaped fill along the southern side of the Monte Cresta Drive right-of-way; 2) the presence of the thin undocumented fill in the eastern portion of the site; 3) the steepness of the site for access for construction of foundation piers; 4) the need to dispose of roof water and storm water runoff on the site (rather than into an existing storm drain system); and 5) the probability of severe ground shaking at the site during a major earthquake in the area.

Due to the steep site conditions, the existing and proposed fill in the northern portion of the site and within the Monte Cresta Drive right-of-way, and the presence of fill in the eastern portion of the property, the proposed residence, driveway deck, and retaining wall along the southern side of the fire truck turnaround should be supported on reinforced concrete piers embedded in the weathered Franciscan Complex bedrock. The minimum required diameter and depth of the piers will depend on the depth to bedrock at the pier locations, the vertical and lateral loads from the proposed residence and the retaining wall for the fire truck turnaround, and whether the top of the piers will be restrained or unrestrained from rotation.

Existing undocumented fill in the Monte Cresta Drive right-of-way and in the northern portion of the site that will be dedicated for the fire truck turnaround should be removed and recompacted with observation and testing by our staff during earthwork construction.

Since no grading or ground-supported structures other than the residence are proposed in the eastern portion of the property, and the residence and retaining wall for the fire truck turnaround will be supported on reinforced concrete piers, the existing fill in the eastern portion of the property may remain in-place without presenting a risk to the proposed residence or _fire truck turnaround. Construction of reinforced concrete piers for support of the proposed residence will increase the stability of the existing fill.

Storm water runoff from roof downspouts and hardscape surfaces will need to be collected and disposed of on-site by means of a suitable storm water detention system with metered release to a level spreader at a suitable location. Storm water should not be disposed of in the eastern portion of the site where fill is present. Depending on design and details for the storm water disposal system, constructing a row of reinforced concrete stitch piers along the downslope side of a level spreader would probably be desirable.

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Because subsurface conditions may vary from those encountered at the locations of our borings, and to observe that our recommendations are properly implemented, we recommend that we be retained to: 1) review the project plans for conformance with our recommendations; and 2) observe and test during earthwork and foundation construction.

FOUNDATIONS
Reinforced Concrete Piers
Due to the steepness of the site and the presence of undocumented fill, the proposed residence, driveway deck, and retaining wall for the fire truck turnaround should be supported on reinforced concrete piers embedded in competent sandstone bedrock below any fill and colluvium. Reinforced concrete piers should have a minimum diameter of at least 16-inches and should extend at least 15 feet below adjacent grade and at least 12 feet into weathered bedrock, whichever is deeper. The structural engineer may require deeper embedment into bedrock to resist lateral loads imposed on the piers. To account for the variable depth to bedrock, the piers should be designed for lateral creep loads from the existing fill and colluvium assuming the depth to bedrock varies from 2 feet to 6 feet below grade as described in the following section of this report titled "Lateral Loads." Although the structural steel frame of the residence is expected to be rigid and to resist rotation of the top of the piers, the structural engineer may want to consider connecting the top of the piers or the lower portion of the steel frame with tie beams, at least below the eastern side of the residence, to provide additional restraint to rotation of the top of the piers thereby increasing the lateral load capacity and decreasing pier deflection.

Reinforced concrete piers may be designed for allowable skin friction of 550 pounds per square foot for dead plus live loads in weathered bedrock with a one-third increase allowed when considering additional short-term wind or seismic loading. Skin friction support in native soil and fill should be neglected in design. Piers should be reinforced with the equivalent of at least four, No. 6 bars in the vertical direction or as determined by the structural engineer to resist bending from lateral loads. Piers should have a center-tocenter spacing of at least three pier diameters.

Pier drilling should be observed by a member of our staff to confirm that the pier holes extend at least the required minimum depth below grade, extend at least the minimum required depth into bedrock, and are properly cleaned of all loose or soft soil and debris.

The pier depths recommended above may require adjustment if differing conditions are encountered during drilling. Although we expect that moderate sized drilling equipment can obtain the required depths, a rock bit equipped with carbide teeth or a rock core barrel will probably be required due to the hardness of the bedrock at the site.

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Concrete should be placed in the pier holes as soon as practical after drilling. Although considered unlikely, seepage of ground water into the pier holes may occur during pier drilling, and it is possible that seepage of ground water could cause some sloughing or caving of the soil above bedrock if concrete is not placed in pier excavations soon after drilling. If water seeps into the pier holes, and water cannot be successfully pumped from the pier holes, concrete will need to be placed in the pier holes by the tremie method.

This can be further evaluated during the drilling of the initial pier holes.

Lateral Loads
To account for the variable depth to bedrock and a potential lateral creep force from the existing fill and colluvium, the piers should be designed for depth to bedrock of 2 feet and 4 feet below grade below the western portion of the residence and for a depth to bedrock of 4 feet and 6 feet below grade below the eastern portion of the residence.

To account for downslope soil creep, a lateral earth pressure of at least 85 pounds per cubic foot should be assumed to act on the portion of the piers above bedrock. This lateral creep pressure should be assumed to act over two pier diameters. The lateral creep pressure and other lateral loads imposed on the piers may be assumed to be resisted by passive earth pressure simulated by an equivalent fluid pressure of 400 pounds per cubic foot acting over two pier diameters starting no higher than 3 feet below the surface of the bedrock. Passive resistance acting against the portion of the pier above three feet below the surface of the bedrock should be neglected in design.

Settlement
Thirty-year differential settlement due to static loads is not expected to exceed 3/4-inch across the pier-supported residence and driveway deck, provided the pier foundations are designed and constructed as recommended above.

RETAINING WALLS
Retaining walls should be designed to support adjacent native material, fill, and backfill.

Retaining walls with level backfill that are not free to deflect or rotate, such as retaining walls that are part of the residence or that are buttressed by the driveway deck, should be designed to resist an at-rest pressure simulated by an equivalent fluid pressure of 45 pounds per cubic foot plus a uniform lateral pressure of 8H in pounds per square foot, where H is the height of the wall in feet. Retaining walls with level backfill that are free to rotate, such as site retaining walls structurally separated from the residence, may be designed to resist an equivalent fluid pressure of 45 pounds per cubic foot.

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Retaining walls with sloping backfill should be designed for an additional equivalent fluid pressure of 1 pound per cubic foot for every 1 degree of slope inclination. Where retaining walls will be subjected to surcharge loads, such as from adjacent foundations, vehicles, or construction loading, the walls should be designed for an additional uniform lateral pressure equal to one-half of the vertical surcharge pressure.

Based on the site peak ground acceleration, on Seed and Whitman (1970), Al Atik and Sitar (2010), and Lew et al. (2010), seismic loads on flexible retaining walls that can yield, such as site retaining walls, may be simulated by a line load of 8H2 (in pounds per foot, where H is the wall height in feet). Seismic loads on rigid retaining walls that cannot yield, such as building retaining walls, may be subjected to a seismic load as high as about 14H2
• This seismic surcharge line load may be assumed to act at 1/3H above the base of the wall (in addition to the active wall design pressure of 45 pounds per cubic foot for level wall backfill with an additional 1 pound per cubic foot for every 1 degree of slope inclination for sloping backfill).

To prevent buildup of water pressure from surface water infiltration, a subsurface drainage system should be installed behind retaining walls. The drainage system should consist of a 4-inch diameter perforated pipe (with perforations facing down) embedded in a 12-inch wide section of ½- to ¾-inch, clean, crushed gravel. Backfill above the perforated drain pipe should also consist of½- to ¾-inch, clean, crushed gravel to within about 1 ½ to 2 feet below exterior finished grade.

A layer of filter fabric, such as Mirafi 140N, should be wrapped around the crushed rock to protect it from infiltration of the adjacent soil and backfill. The upper 1 ½ to 2 feet of the backfill should consist of compacted on-site soil. The perforated pipe should discharge to a suitable storm water detention system. Damp-proofing should be installed in areas where retaining wall dampness and/or efflorescence would be undesirable.

Miradrain, Enkadrain, or other drainage panels approved by our staff may be used for wall drainage as an alternative to the gravel drainage system described above. If used, the drainage panels should extend from a depth of about 1 foot below the top of the wall backfill down to the drain pipe at the base of the wall. A minimum 12-inch wide section of½- to ¾-inch clean crushed gravel protected by filter fabric should be installed around the drain pipe, as recommended above.

Backfill placed behind retaining walls should be compacted to at least 90 percent relative compaction using light compaction equipment. If heavy equipment is used for compaction of wall backfill, the walls may need to be temporarily braced. Ideally, backfill behind retaining walls should be placed on level benches, rather than directly on the sloping ground surface.

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The retaining wall along the south side of the fire truck turnaround, and retaining walls around the upslope side of the lower levels of the residence, should be supported on reinforced concrete piers that are designed and constructed as recommended above.

SLABS-ON-GRADE
General Slab Considerations
To reduce the potential for differential movement of concrete slabs-on-grade, at least the upper 6-inches of the subgrade should be scarified and compacted at a moisture content above the laboratory optimum value. Soil subgrades should be kept moist up until the time the non-expansive fill, aggregate base, and/or vapor barrier is installed. Slab subgrades and non-expansive fill should be prepared and compacted as recommended in the section of this report titled "Earthwork." All soft, moist, or otherwise unsuitable soils should be removed from slab-on-grade areas. Exterior flatwork and interior slabs should be underlain by a layer of non-expansive fill as recommended below. The non-expansive fill should consist of Class 2 aggregate base or clayey soil with a Plasticity Index of 15 or less.

Considering the potential for some differential movement of the surface and near-surface soils, we expect that reinforced slabs will perform better than unreinforced slabs.

Consideration should be given to using a control joint spacing on the order of 2 feet in each direction for each inch of slab thickness.

For improved slab performance, existing fill in areas that will be covered by concrete slabs-on-grade should be removed and recompacted on a series of level benches as recommended for structural fill.

Exterior Flatwork
Concrete walkways and exterior flatwork should be at least 4 inches thick and should be constructed on at least 6 inches of compacted Class 2 aggregate base over a properly prepared and compacted subgrade. For improved performance, exterior slabs-on-grade could be constructed with a thickened edge to improve edge stiffness and to reduce the potential for water seepage under the edge of the slabs and into the underlying base and subgrade. In our opinion, thickened slab edges should be at least 8 inches wide and should extend to a depth of at least 4 inches below the bottom of the underlying aggregate base layer.

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Interior Slabs
Interior concrete slab-on-grade floors should be constructed on a layer of non-expansive fill at least 6 inches thick. The non-expansive fill should be placed and compacted on a properly prepared and compacted subgrade. In areas where dampness of concrete floor slabs would be undesirable, such as within the interior of the residence, concrete slabs should be underlain by at least 6 inches of free-draining gravel, such as ½- to ¾-inch, clean, crushed gravel with no more than 5 percent passing the ASTM No. 200 sieve. Pea gravel should not be used for this capillary break material. The crushed rock layer should be densified and leveled with vibratory equipment and may be considered as the nonexpansive fill recommended above.

To reduce vapor transmission up through concrete floor slabs, the crushed rock layer should be covered with a high quality vapor barrier conforming to the requirements of ASTM E 1745 Class A, with a water vapor transmission rate less than or equal to 0.01 perms, such as 15-mil thick Stego Wrap Class A. The vapor barrier should be placed directly below the concrete slab. Installation of a layer of sand above the vapor barrier is not recommended. The vapor barrier should be installed in accordance with ASTM E 1643. All seams and penetrations of the vapor barrier should be sealed in accordance with manufacturer's recommendations.

The permeability of concrete is affected significantly by the water:cement ratio of the concrete mix, with lower water:cement ratios producing more damp-resistant slabs and stronger concrete. Where moisture protection is important and/or where the concrete will be placed directly on the vapor barrier, the water:cement ratio should be 0.45 or less. To increase the workability of the concrete, mid-range plasticizers can be added to the mix.

Water should not be added to the concrete mix unless the slump is less than specified and the water:cement ratio will not exceed 0.45.

Other steps that may be taken to reduce moisture transmission through the concrete slabson-grade include moist curing for 5 to 7 days and allowing the slab to dry for a period of two months or longer prior to installing floor coverings. Prior to installation of floor coverings, it would be appropriate to test the slab moisture content for adherence to the manufacturer's requirements and to determine whether a longer drying time is necessary.

PAVEMENT FOR FIRE TRUCK TURNAROUND
Based on our borings, the subgrade for the fire truck turnaround will be composed of silty sand with an R-value greater than 30. If the turnaround will be surfaced with asphalt concrete, the pavement section should consist of at least 3 inches of asphalt concrete on at least 6 inches of Class 2 aggregate base on a properly prepared and compacted subgrade.

This pavement section corresponds to a Traffic Index slightly above 5.0.

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If the fire truck turnaround will be surfaced with concrete, the pavement section should consist of at least 5½ inches of concrete on at least 4 inches of Class 2 aggregate base on a properly prepared and compacted subgrade. Unreinforced concrete for the 5½-inch thick pavement should have a 28-day compressive strength of at least 3,500 psi. The pavement should be laterally constrained with curbs or shoulders, and sufficient control joints should be incorporated in the design and construction to limit and control cracking.

Existing fill in the area for the proposed turnaround should be removed and recompacted as described in this report. The fill, subgrade, and aggregate base below the pavement section should be prepared and compacted as recommended below.

EARTHWORK
Clearing and Subgrade Preparation
All deleterious materials, such as concrete, pavement, abandoned utility lines, soft or loose soils, existing fill, vegetation, root systems, topsoil, etc., should be cleared from areas of the site to be built or paved on. The actual stripping depth should be determined by a member of our staff in the field at the time of construction. Excavations that extend below finished grade should be backfilled with structural fill that is water-conditioned, placed, and compacted as recommended in the section of this report titled "Compaction." After the site has been properly cleared, stripped, and excavated to the required grades, exposed soil surfaces in areas to receive structural fill, slabs-on-grade, or pavements should be scarified to a depth of 6 inches, moisture conditioned, and compacted as recommended for structural fill in the section of this report titled "Compaction." Undocumented fill in the area for the proposed fire truck turnaround should be removed and recompacted on level benches with observation and testing by our staff during earthwork construction. Remedial grading of the existing fill may need to extend beyond the edge of the proposed fire truck turnaround depending on the final configuration and elevation of the turnaround.

Material for Fill
All on-site soil containing less than 3 percent organic material by weight (ASTM D2974) may be suitable for use as structural fill. Structural fill should not contain rocks or pieces larger than 6 inches in greatest dimension and no more than 15 percent larger than 2.5 inches. Imported, non-expansive fill should have a Plasticity Index no greater than 15, should be predominately granular, and should have sufficient binder so as not to slough or cave into foundation excavations or utility trenches. A member of our staff should evaluate and approve proposed import materials prior to their delivery to the site.

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Compaction
Scarified soil surfaces and all structural fill should be compacted in uniform lifts no thicker than 8 inches, conditioned to the appropriate moisture content, and compacted as recommended for structural fill in Table 2 below. The relative compaction and moisture content recommended in Table 2 is relative to ASTM Test D 1557, latest edition.

Table 2. Compaction Recommendations
Kraft Residence
General
• Scarified subgrade in areas
to receive structural fill.
• Structural fill composed
of on-site soil.
• Structural fill composed
of non-expansive fill.
• Structural fill below a
depth of 4 feet.

Fire Truck Turnaround
• Upper 12-inches of soil
below aggregate base.
• Aggregate base.

Utility Trench Backfill
• On-site soil.
• Imported sand
Belmont, California
Relative Compaction*
90 percent
90 percent
90 percent
93 percent
95 percent
95 percent
90 percent
95 percent
* Relative to ASTM Test D1557, latest edition.

Temporary Slopes and Excavations
Moisture Content*
Above optimum
Above optimum
Above optimum
Near optimum
Near optimum
Near optimum
Near optimum
Near optimum
The contractor should be responsible for the design and construction of all temporary slopes and any required shoring or bracing. Shoring and bracing should be installed in accordance with all applicable local, state, and federal safety regulations, including current OSHA excavation and trench safety standards.

Because of the potential for variation of the on-site soil, field modification of temporary cut slopes may be required. Unstable materials encountered on or near excavations and slopes during and after excavation should be trimmed off even if this requires cutting the slopes back to a flatter inclination. Protection of structures near cuts and excavations will also be the responsibility of the contractor.

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Finished Slopes
We recommend that finished slopes be cut or filled to an inclination no steeper than 2: 1 (horizontal:vertical). Exposed slopes may be subject to minor sloughing and erosion that would require periodic maintenance. We recommend that all slopes and soil surfaces disturbed during construction be planted with erosion resistant vegetation.

Surface Drainage
Finished grades should be designed to prevent ponding of water and to direct surface water runoff away from foundations and edges slabs and pavements, and toward suitable collection and discharge facilities. Slopes of at least 2 percent are recommended for flatwork and pavement areas with 5 percent preferred in landscape areas within 8 feet of the residence, where possible.

Storm water runoff from roof downspouts and hardscape surfaces will need to be collected and disposed of on-site by means of a suitable storm water detention system.

We recommend the storm water detention system include metered release that discharges to a level spreader at a suitable location in the western portion of the site where existing fill is not present. Depending on design and details for the storm water disposal system, constructing a row of reinforced concrete stitch piers along the downslope side of a level spreader would probably be desirable.

Drainage facilities should be observed to verify that they are adequate and that no adjustments need to be made, especially during the first two years following construction.

We recommend an as-built plan be prepared to show the locations of surface and subsurface drain lines and clean-outs. Drainage facilities should be periodically checked to verify that they are continuing to function properly. It is likely the drainage facilities will need to be periodically cleaned of silt and debris that may build up in the lines.

FUTURE SERVICES
Plan Review
Romig Engineers should review the final grading and foundation plans for conformance with the recommendations presented in this report. We should be provided with these plans as soon as possible upon their completion in order to limit the potential for delays in the permitting process that might otherwise be attributed to our review process. In addition, it should be noted that many of the local building and planning departments now require a "clean" geotechnical plan review letter prior to acceptance of plans for their final review. Since our plan reviews typically result in recommendations for modification of the plans, our generation of a "clean" review letter often requires two iterations.

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At a minimum, we recommend that the following note be added to the plans: "Earthwork, slab subgrade and non-expansive fill preparation, pier drilling, foundation construction, retaining wall drainage and backfilling, utility trench backfilling, pavement construction, and site drainage should be performed in accordance with the recommendations in the geotechnical report, dated January 29, 2016, prepared by Romig Engineers, Inc. Romig Engineers should be notified at least 48 hours in advance of earthwork and foundation construction and should observe and test during earthwork, foundation, and pavement construction as recommended in the geotechnical report." Construction Observation and Testing
The earthwork and foundation phases of construction should be observed and tested by us to: 1) confirm that subsurface conditions are compatible with those used in the analysis and design; 2) observe compliance with the design concepts, specifications, and recommendations; and 3) allow design changes in the event that subsurface conditions differ from those anticipated. The recommendations in this report are based on a limited amount of subsurface exploration. The nature and extent of variation across the site may not become evident until construction. If variations are exposed during construction, it will be necessary to reevaluate our recommendations.
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REFERENCES
Aerial Photographs
United States Geologic Survey Library, Menlo Park, California (USGS); USDA (United States Department of Agriculture Adjustment Administration (CIV series); WAC Corporation, Eugene, Oregon (WAC); and Pacific Aerial Surveys, Oakland, California (PAS): black and white vertical stereo pairs, except as noted.

Source Imagery Date Scale
PAS AV-01-01-30/31 6/18/37 1 :12,000
PAS AV-9-16-9/10 7/29/46 1:23,600
PAS AV-170-12-09/10 5/10/55 1:10,000
PAS AV-933-11-08/09 10/28/69 1:12,000
PAS AV-1705-10-09/10 5/30/79 1:12,000
PAS AV-2020-10-09/10 6/19/81 1:12,000
PAS A V-2265-10-08-09 6/06/83 1:12,000
PAS AV-2670-10-8/9 10/15/85 1:12,000
PAS AV-4916-11-8/9 9/07/95 1:12,000
PAS SMT-AV-6600-11-8/9 8/16/00 1:12,000
Publications and Reports
Al Atik, L., and Sitar, N., 2010, Seismic Earth Pressures on Cantilever Retaining Structures, Journal ofGeotechnical and Geoenvironmental Engineering, ASCE Vol. 136, No. 10.

Brabb, E.E., Graymer, R.W., and Jones, D.L., 1998, Geology of the Onshore Part of San Mateo County, California U.S. Geological Open-File 98-137.

Brabb, E.E., and Pampeyan, E.H., 1983, Geologic Map of San Mateo County, California, U.S. Geological Survey Map I-1257-A.

California Department of Conservation, Division of Mines and Geology (DIG), 1994, FaultRupture Hazard Zones in California, Special Publication 42.

City of Belmont, 1988, Ground Movement Potential and Geologic Hazard Policy Map. in San Juan Hills Area Plan, adopted March, 1988.

Lew, M., Al Atik, L., Sitar, N., Pourzanjani, M., & Hudson, M., 2010, Seismic Earth Pressures on Deep Building Basements, SEAOC 2010 Convention Proceedings.

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Pampeyan, E.H, 1981, Geology and Former Shoreline Features of the San Mateo 7.5 Minute Quadrangle, San Mateo County, California, USGS Open-File Report 81-839, Scale 1 :24,000.

Pampeyan, E.H., 1994, Geologic Map of the Montara Mountain and San Mateo 7-1/2' Quadrangles, San Mateo County, California, USGS Miscellaneous Investigations Series Map I-2390, Scale l :24,000
Romig Engineers, Inc, 2008, Geologic and Geotechnical Engineering Feasibility Study, Monte Cresta Drive Through Road. Belmont. California, report dated June 30, 2008.

Romig Engineers, Inc., 2013, Geotechnical Report, Campbell Residence, Monte Cresta Drive. Belmont, California, report dated May 31, 2013.

Romig Engineers, Inc., 2015, Feasibility Evaluation, Single-Family Residence, Monte Cresta Drive (APN 043-165-180), Belmont, California, report dated December 3, 2015.

William Cotton, W. & Associates, April 1985, Engineering Geologic Map. San Juan Canyon Study Area. Belmont, California, Scale 1 :2,400.

William Cotton and Associates, April 1985, Geologic Hazard Analysis of the San Juan Canyon Study Area, Belmont, California._
William Cotton and Associates, April 1985, Ground Movement Potential and Geologic Hazard Policy Map, San Juan Canyon Study Area, Belmont. California, Scale 1 :2,400._ Working Group on California Earthquake Probabilities (WGCEP), 2015, Long-Term TimeDependent Probabilities for the Third Uniform California Earthquake Rupture Forecast, Version 3 (VCERF 3}. U.S. Geological Survey Open File Report 2013-1165.

William Cotton and Associates, April 1985, Ground Movement Potential Map, San Juan Canyon Study Area Belmont, California._
Working Group on California Earthquake Probabilities (WGCEP), 2008, The Uniform California Earthquake Rupture Forecast, Version 2 (VCERF 2). U.S. Geological Survey Circular Open File Report 2007-1437.
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Scale: 1 inch= 2000 feet
Base is United States Geological Survey San Mateo 7.5 Minute Quadrangle, dated 1997.

VICINITY MAP

KRAFT RESIDENCE

BELMONT, CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURE 1
JANUARY 2016
PROJECT NO. 3614-1
429

PROPOSED

TURN-AROUND

FIRETRUCK
LEGEND
Approximate Scale: 1 inch = 30 feet.
0 15 30

PROPOSED

DRIVEWAY
RAMP

PROPOSED

THREE-STORY

RESIDENCE
60feet
Base is Site Plan r ared by Triad/Homes Associates, dated November 10, 2015.

SITE PLAN

KRAFT RESIDENCE

BELMONT, CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURE2
JANUARY 2016
PROJECT NO. 3614-1
430
Qaf-s
Qafr
Qaf-d
KJfs
,,<. s,
X
y

MAP LEGEND
Shallow fill overlying lateral margin of ca. 1960 fill mass. "Wedge" fill supporting road.
ca. 1960 fill mass.

Franciscan Assemblage Sandstone.

Strike and dip of bedding.

Bedrock outcrop.

Excavated cut.

LEGEND
Approximate Scale: 1 inch= 30 feet.

Qaf-d
0 15 30 60feet
Base is Surve prepared b Triad/Homes Associates, dated November 10, 2015.

KRAFT

SITE GEOLOGIC MAP

RESIDENCE

BELMONT, CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURE3
JANUARY 2016
PROJECT NO. 3614-1
431

MAP LEGEND
Qsr Slope wash, ravine fill, and colluvium (Holocene)
Qf Artificial fill (Holocene)
fs Sandstone (Cretaceous and Jurassic)
fg Greenstone (Cretaceous and Jurassic)
fsr Sheared rock (Cretaceous and Jurassic)
sp Serpentinite (Cretaceous and Jurassic)
f s
Scale: 1 inch= 2000 feet
\ .
.. •. . l • ,; �-.

I
1000 2000
,
t
}:
fc
. . .... \ ,., \
4000 feet
Base is Geologic Map of the Montara Mountain and San Mateo 7.5 Minute Quadrangles, San Mateo County, California, (Pampeyan, 1994).

VICINITY GEOLOGIC MAP
KRAFf RESIDENCE

BELMONT, CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURE4
JANUARY 2016
PROJECT NO. 3614-1
432
M
Als
KJfs
sp
)·
LEGEND
Artificial fill
Active Landslide
Franciscan Complex Sandstone
Serpentinite
Geologic Contact
Bedding Orientation
Fracture
Landslide, arrows indicate
direction of moyement
Colluvium
.,
t,13.-.i
.
. .
-o.�-- . . .. t\' ..
i. -
...
. , .
.. 'l··
... ,,,,. t /
.. ;;,- r·.
. "-•::> _ ,,,,
6' ·"" · .... �
)
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j
Scale: 1 inch = 200 feet
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. .
. -- ...
-.-�
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.1
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200 400feet
Base is Engineering Geologic Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

SAN JUAN CANYON ENGINEERING GEOLOGIC MAP

KRAFT RESIDENCE

BELMONT, CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURES
JANUARY 2016
PROJECT NO. 3614-1
433

MAP LEGEND
Pdf Steep to very steep terrain susceptible to debris flows.

Ps Relatively unstable material, less than 10 feet deep susceptible to shallow slope failures.

Pd Relatively unstable landslide debris greater than 10 feet in depth.

Pfs Potential failure within large areas of engineered fill susceptible to settlement, landsliding, and debris flow.

Sbr Level to moderately sloping ground underlain by bedrock within several feet of the ground surface. Soil cover may be subject to shallow sliding, soil creep, or settlement.

Moving shallow landslides, commonly less than 10 feet thick.

Scale: 1 inch = 200 feet
100 200 400feet
Base is Ground Movement Potential Map of the San Juan Canyon Study Area, Belmont, California, by William Cotton and Associates, dated April 1985.

KRAFT

SAN JUAN CANYON GROUND MOVEMENT POTENTIAL MAP

RESIDENCE

BELMONT,CALIFORNIA
ROMIG ENGINEERS, INC.

FIGURE6
JANUARY 2016
PROJECT NO. 3614-1
434
r
J
I
I
I

APPENDIXA

FIELD INVESTIGATION
The soils encountered during drilling were logged by our representative and samples were obtained at depths appropriate to the investigation. The samples were taken to our laboratory where they were evaluated and classified in accordance with the Unified Soil Classification System. The logs of our borings, and a summary of the soil classification system (Figure A-1) and bedrock descriptions used on the boring logs (Figure A-2) are attached.

Several tests were performed in the field during drilling. The standard penetration test resistance was determined by dropping a 140-pound hammer through a 30-inch free fall and recording the blows required to drive the 2-inch (outside diameter) sampler 18 inches. The standard penetration test (SPT) resistance is the number of blows required to drive the sampler the last 12 inches and is recorded on the boring logs at the appropriate depths. Soil samples were also collected using a 3-inch O.D. drive sampler. The blow counts shown on the logs for this larger sampler do not represent SPT values and have not been corrected in any way.

The locations and elevations of the exploratory borings were determined by pacing using the site plan, dated November 10, 2015, prepared by Triad/Homes Associates, and should be considered accurate only to the degree implied by the method used.

The boring logs and related information depict our interpretation of subsurface conditions only at the specific location and time indicated. Subsurface conditions and ground water levels at other locations may differ from conditions at the locations where sampling was conducted. The passage of time may also result in changes in the subsurface conditions. ❖ ❖ ❖
ROMIG ENGINEERS, INC.
435
uses SOIL CLASSIFICATION

PRIMARY DIVISIONS

CLEAN GRAVEL
COARSE GRAVEL (< 5% Fines)
GRAINED GRAVEL with

SOILS FINES
(< 50 % Fines) CLEAN SAND
SAND (< 5% Fines)
SAND

WITH FINES

FINE SILT AND CLAY
GRAINED Liquid limit < 50%
SOILS
(> 50 % Fines) SILT AND CLAY
Liquid limit > 50%

HIGHLY ORGANIC SOILS

BEDROCK

RELATIVE DENSITY
SAND & GRAVEL BLOWS/FOOT*
VERY LOOSE 0 to 4
LOOSE 4 to 10
MEDIUM DENSE 10 to 30
DENSE 30 to 50
VERY DENSE OVER50
SOIL
TYPE
GW .c:,� .e.,,_,; ..

GP I�
GM �
GC �
SW
SP
Sl\1
SC
ML
CL
OL
. �·o·
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...
..
. . .
. .
'"'
-·
�
'''''
�$
:•:•:

SECONDARY DIVISIONS
Well graded gravel, gra,·el-sand mixtures, little or no fines.

Poorly graded gravel or gravel-sand mixtures, little or no fines.

Silty gravels, gravel-sand-silt mixtures, non-plastic fines.

Clayey gravels, gravel-sand-clay mixtures, plastic fines.

Well graded sands, gravelly sands, little or no fines.

Poorly graded sands or gravelly sands, little or no fines.

Silty sands, sand-silt mixtures, non-plastic fines.

Clayey sands, sand-clay mixtures, plastic fines.

Inorganic silts and very fine sands, with slight plasticity.

Inorganic clays of low to medium plasticity, lean clays. ii
Organic silts and organic clays oflow plasticity.
lno.-g,nic silt, micaccou, "' diatomaccous fine s,ndy "'silty soil.

Inorganic clays of high plasticity, fat clays.

Organic clays of medium to high plasticity, organic silts.

Pt :I: Peat and other highly organic soils.

BR Weathered bedrock.

CONSISTENCY
SILT&CLAY STRENGTHA BLOWS/FOOT*
VERY SOFT 0 to 0.25 0 to 2
SOFT 0.25 to 0.5 2 to 4
FIRM 0.5 to 1 4 to 8
STIFF 1 to 2 8 to 16
VERY STIFF 2 to4 16 to 32
HARD OVER4 OVER32

GRAIN SIZES
BOULDERS COBBLES -----GRAVEL -"'T"""----------,.-----SAND --r----------1

SILT & CLAY
12"
COARSE
3"

SIEVE OPENINGS
FINE

0.75"

COARSE MEDIUM FINE
4 10 40 200
U.S. STANDARD SERIES SIEVE
Classification is based on the Unified Soil Classification System; fines refer to soil passing a No. 200 sieve. * Standard Penetration Test (SPT) resistance, using a 140 pound hammer falling 30 inches on a 2 inch O.D. split spoon sampler; blow counts not corrected for larger diameter samplers. " Unconfined Compressive strength in tons/sq. ft. as estimated by SPT resistance, field and laboratory tests, and/or visual observation.

KEY TO EXPLORATORY BORING LOGS

KRAFT RESIDENCE

BELMONT, CALIFORNIA
rn

KEY TO SAMPLERS
Modified California Sampler (3-inch O.D.)
Mid-size Sampler (2.5-inch O.D.)
Standard Penetration Test Sampler (2-inch O.D.)
FIGUREA-1
JANUARY 2016
PROJECT NO. 3614-1
ROMIG ENGINEERS, INC.
436

WEATHERING
Fresh
Rock fresh, crystals bright, few joints may show
slight staining. Rock rings under hammer if crystalline.

Very Slight
Rock generally fresh, joints stained, some joints may
show thin clay coatings, crystals in broken face
show bright. Rock rings under hammer if crystalline.

Slight
Rock generally fresh, joints stained, and discoloration extends into rock up to 1 inch. Joints may contain clay.

In granitoid rocks some occasional feldspar crystals are dull and discolored. Crystalline rocks ring under hammer.

Moderate
Significant portions of rock show discoloration and
weathering effects. In granitoid rocks, most feldspars
are dull and discolored; some are clayey. Rock has dull sound under hammer and shows significant loss of
strength as compared with fresh rock.

Moderately Severe
All rock except quartz discolored or stained. In granitoid rocks, all feldspars dull and discolored and majority show kaolinization.

Rock shows severe loss of strength and can be excavated with geologist's pick. Rock goes "clunk" when struck.

Severe
All rock except quartz discolored or stained. Rock "fabric" clear and evident, but reduced in strength to strong soil. In granitoid rocks, all feldspars kaolinized to some extent. Some fragments of strong rock usually left.

Very Severe
All rock except quartz discolored and stained. Rock "fabric" discernible, but mass effectively reduced to "soil" with only fragments of strong rock remaining.

Complete
Rock reduced to "soil". Rock fabric not discernible or discernible only in small scattered locations. Quartz may be present as dikes or stringers.

HARDNESS
Very hard
Cannot be scratched with knife or sharp pick. Hand
specimens requires several hard blows of geologist's.

Hard
Can be scratched with knife or pick only with difficulty.

Hard blow of hammer required to detach hand
specimen.

Moderately Hard
Can be scratched with knife or pick. Gouges or grooyes
to 1/4 inch deep can be excavated by hard blow of point of a geologist's pick. Hard specimen can be detached
by moderate blow.

JOINT BEDDING AND FOLIATION SPACING
Medium
Can be grooved or gouged 1/16 inch deep by firm pressure on knife or pick point. Can be excavated in small chips to pieces about 1 inch maximum size by hard blows of the point ofa geologist's pick.

Soft
Can be gouged or grooved readily with knife or pick point. Can be excavated in chips to pieces several inches in size by moderate blows of a pick point. Small thin pieces can be bracken by finger pressure.

Very Soft
Can be carved with knife. Can be excavated readily with point of pick. Pieces I inch or more in thickness can be broken with finger pressure. Can be scratched readily by fingernail.

ROCK QUALITY DESIGNATOR (RQD)
Spacing Joints Bedding and Foliation RQD, as a percentage Descriptor Less than 2 in. Very Close
2 in. to 1 ft. Close
1 ft. to 3 ft. Moderately Close
3 ft. to 10 ft. Wide
More than 10 ft. Very Wide
KEY
KRAFT

TO BEDROCK DESCRIPTIONS

RESIDENCE

BELMONT, CALIFORNIA
Very Thin
Thin
Medium
Thick
Very Thick
ROMIG ENGINEERS, INC.

Exceeding 90
90 to 75
75 to 50
50 to 25
Less than 25
Excellent
Good
Fair
Poor
Very Poor
FIGUREA-2
JANUARY 2016
PROJECT NO. 3614-1
437
DRILL TYPE: Track-mounted CME-55 with 8" Hollow Stem Auger and Auto Hammer DEPTH TO GROUND WATER: Not Encountered. SURFACE ELEVATION: 100 feet.

CLASSIFICATION AND DESCRIPTION
Fill: Grayish brown, Sandy Lean C ay with Gravel, moist, fine to coarse grained sand, fine to coarse angular to rounded gravel, clayey sand lenses, low to moderate plastic fines, large rock and concrete fragments, asphalt concrete debris.

Tannish brown, Silty Sand, moist, fine to medium
grained sand, low plasticity fines.

Franciscan Complex: Light brovm, Sandstone, slightly moist, fine to medium grained, friable, severely weathered.

Bottom of Boring at 10.2 feet.

Note: The stratification lines represent the approximate boundary between soil and rock types, the actual
transition may be gradual.
*Measured using Torvane and Pocket Penetrometer devices.

EXPLORATORY

KRAFT RESIDENCE
BORING LOG EB-1

BELMONT, CALIFORNIA
--
:;:; �
C';l
< uu <U �� ...
� w
/:1.,
IZl .,_ >- - 0 '-'
IZl f-, © z� IZl ...l IZl - 0 - UIZl w 0
d� � IZl
�Cl �
Stiff CL
Very
Stiff
Dense
Medium BR
ROMIG ENGINEERS, INC.
...l
0 �
IZl
...l -
0 IZl
,-., f-,
w
w
E::,
�
/:1.,
w
Cl
15 20
LOGGED BY: PV
DATE DRILLED: 12/23/15
f *
...l ,.... � t
< � v.i t:, t:, � §, E-o ::i:: � � ffi ts � u
� � �
i:il E-o u �
...l r;j �
v.i ffi �
cil
gi
E-o �
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<'-l t:: v.i v.i �
19 11
43 18
I 50/4" 9
50,'2.5" 6
BORINGEB-1
JANUARY 2016
PROJECT NO. 3614-1
438
DRILL TYPE: Track-mounted CME-55 with 8" Hollow Stem Auger and Auto Hammer DEPTH TO GROUNDWATER: Not Encountered. SURFACE ELEVATION: 102feet.

CLASSIFICATION AND DESCRIPTION
Tannish brown, Silty Sand, moist, fine to medium
grained sand, low plasticity fines.

Franciscan Complex: Light brown, Sandstone, slightly moist, fine to medium grained, friable, severely weathered.

Bottom of Boring at 10.2 feet.

Note: The stratification lines represent the approximate boundary between soil and rock types, the actual
transition may be gradual.
*Measured using Torvane and Pocket Penetrometer devices.

EXPLORATORY
KRAFT
BORING LOG EB-2

RESIDENCE

BELMONT, CALIFORNIA
,,...._
----
>- ::,i: < uu cu ffiO f-, � .!?:!l
Cl'J ... .... - 0 '--'
Cl'J (i) z� rll
o_ I
u rll
� ffi �o
Medium
Dense
to
Dense
Medium
ROMIG ENGINEERS, INC.
...l
w 0
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f-, �
>-
0 ...l - ...l
rll 0rll
SM
BR
LOGGED BY: PV
DATE DRILLED: 12/23/15
? ,-... G:' G::' � t
Cl)
f-, 0 t, t,
w §, r-' :i: w � � � 1ri
'--' .... u r-' ts 0 � �
i;.J r-' u !
,-J � � � Cl) � Cl) w � � � r:.: 0 i u
en ... :,s: �
50/6" 6
-----'-'._.50/6" 7
15 20
5012"
BORINGEB-2
JANUARY 2016
PROJECT NO. 3614-1
439
I
(
l
l

APPENDIXB

LABORATORY TESTS
Samples from the subsurface exploration were selected for tests to establish the physical and engineering properties of the soils encountered at the site. The tests that were performed are briefly described below.

The natural moisture content was determined in accordance with ASTM D 2216 on nearly all of the samples recovered from the borings. This test determines the moisture content, representative of field conditions, at the time the samples were collected. The results are presented on the boring logs at the appropriate sample depths. ❖ ❖ ❖
ROMIG ENGINEERS, INC.
440
441
442
R O M I G E N G I N E E R S, I N C.

GEOTECHNICAL & ENVIRONMENTAL SERVICES
1390 El Camino Real, Second Floor  San Carlos, California 94070  (650) 591-5224  Fax (650) 591-5251 October 7, 2016
3614-1
Mr. Jeff Kraft RE: GEOTECHNICAL RESPONSE TO
105 Scenic Drive CITY PLANNING REVIEW COMMENTS
Redwood City, California 94062 KRAFT RESIDENCE

MONTE CRESTA DRIVE

BELMONT, CALIFORNIA
PLANNING APPLICATION #2015-0057
Dear Mr. Kraft:

This letter was prepared at your request to respond to City of Belmont Planning Division review comments, dated September 9, 2016, regarding the proposed residence on your property (APN 043-165-180) southwest of the western terminus of Monte Cresta Drive in Belmont, California.

As part of our initial geologic and geotechnical work for your proposed residence, we evaluated the feasibility of constructing the residence and the adjacent fire truck turn-around on the subject site and presented the results in a Feasibility Evaluation Report to you dated December 3, 2015. Our responses to Cotton, Shires and Associates’ December 10, 2015 Geotechnical Peer Review letter addressing our Feasibility Evaluation Report were presented in a letter to you dated April 4, 2016.

Romig Engineers performed a geotechnical investigation for the proposed residence and adjacent fire truck turn-around and presented the results in our design-level geotechnical report dated January 29, 2016. The results of our geotechnical review of the previous Planning-Level Grading and Drainage Plans were presented in a letter dated August 2, 2016.

Our responses to the City’s September 9, 2016 Review Comments pertaining to geotechnical conditions at the site and the proposed site improvements are summarized below.

Public Works Comment 1:

The letter from Romig Engineers dated August 2, 2016 contains no foundation for the statements that “geologic conditions … have not changed significantly” since 2008 and that “no further investigative work is needed to substantiate the findings and conclusions presented in our June 30, 2008 report for the Through Road Extension.” An evidentiary foundation, such as a visual inspection of the site, must be provided for those statements.

Members of Romig Engineers’ staff have visited the eastern end of the Monte Cresta Drive Through Road Alignment several times since 2008 during our geotechnical investigation and plan review services for the Campbell residence and the Kraft residence.

Although we have not field-checked our 2008 geologic mapping along the entire Monte Cresta Drive Through Road Alignment for changes, we are confident that the potentially unstable slopes and existing deep landslides shown on the City’s Geologic Map and Ground Movement Potential Map prepared by Cotton, Shires and Associates, and in 443
Mr. Jeff Kraft Response to Review Comments Page 2 of 5
ROMIG ENGINEERS, INC.

Romig Engineers’ 2008 report for the Through Road Alignment, have not become more stable or less complicated to remediate for a safe and stable Monte Cresta Through Road.

The City’s geologic and geotechnical consultant, Cotton, Shires and Associates, Inc., agreed with the findings and conclusions presented in our June 30, 2008 feasibility report for Through Road Extension and summarized their findings, conclusions, and recommendations in a Geotechnical Peer Review letter to the City of Belmont, dated August 13, 2008. One of the conclusions presented in Cotton, Shires and Associates’ Peer Review letter was that they agreed with Romig Engineer’s assessment “that no significant geotechnical constraints (beyond standard mitigation design) are apparently present along the first 104-foot segment of the road extension from the end of the existing roadway pavement ...”. Recommended mitigation measures for constructing the proposed fire truck turnaround are summarized in our design-level geotechnical report for the Kraft residence.

Our June 30, 2008 Geologic and Geotechnical Investigation and Report for the Monte Cresta Drive Through Road were completed for Mr. Damon Campbell. Earlier this year, Mr. Campbell notified Romig Engineers in writing that we had his permission to release our June 30, 2008 Geologic and Geotechnical Report for the Monte Cresta Through Road to Mr. Kraft for his use and submittal to the City, which we have done.

Public Works Comment 5:

Please note that soils report shall include an analysis of slope stability after the storm water pollution prevention measures are final as requested in items #3 above.

Our January 29, 2016 report includes our evaluation of slope stability after recommended storm water pollution prevention measures are installed. The recommendations in our report are intended to mitigate the potential for surface erosion and slope instability.

Geotechnical Comments:

It is unclear if the civil plans have been updated to address the geotechnical comments.

Please have the project geotechnical engineer and engineering consultants provide a letter addressing each comment below.

Geotechnical Comment 1:

A new catch basin is depicted at lower side of the new cul de sac with a Rim of 94.8. A depicted storm drain pipe connects the new catch basin to an existing catch basin to the east with a Rim of 99.2. Invert elevations should be provided for these two catch basins.

Plans should clarify where flow will be directed and verify that the receiving drainage system has adequate capacity for the new intercepted flow collected from the cul de sac (to include contribution of anticipated flow from the adjacent planned Campbell driveway to the north).

The previous Planning-Level Grading and Drainage Plans referred to in our August 2, 2016 geotechnical plan review letter have been updated and revised to respond to comments from the City of Belmont. The updated civil plans for project planning, sheets C1, C2, and C3, prepared by BKF Engineers, are dated October 5, 2016, and are the plans referred to in our responses below.
444
Mr. Jeff Kraft Response to Review Comments Page 3 of 5
ROMIG ENGINEERS, INC.

The updated civil plans specify invert elevations for the storm water drainage system for the proposed cul-de-sac and fire truck turnaround. We understand from the civil engineer that the cul-de-sac storm drain system has adequate capacity to discharge storm water runoff safely without relying on the capacity of any existing storm water receiving system.

Geotechnical Comment 2:

A drainage spreader is depicted immediately downslope of the detention pipe. The lateral length of this spreader should be specified. It should be clarified that the purpose of this spreader is only to disperse collected residential roof and driveway water.

The civil plans referenced above specify a width of 10 feet for the level spreader downslope from the storm water detention pipe. The purpose of the level-spreader is only to disperse storm water from the roof, driveway, and backdrains behind the on-site retaining walls.

Geotechnical Comment 3:

The geotechnical consultant had previously recommended consideration of the installation of stitch piers near the drainage spreader. The geotechnical consultant should clarify the locations and design of the stitch piers, or explain why an alternative design is acceptable. The consultant should review proposed civil design plans for control of site drainage with respect to potential erosion or adverse slope stability impacts.

The need for reinforced concrete stitch piers below the level-spreader should be determined during construction based on conditions exposed in the detention pipe trench and along the bench cut for the level-spreader. To reduce the potential for erosion of surface soil, a highquality erosion control blanket should be installed for a distance of at least 6 feet along the downslope side of the level-spreader. If the thickness of the soil cover over residual soil and/or bedrock is greater than about 2 to 3 feet along the downslope edge of the erosion control blanket, and if this surface soil appears to be potentially susceptible to rapid downslope creep, slumping, or failure, we will recommend construction of a row of stitch piers along the downslope side of the erosion control blanket.

The depth, diameter, and reinforcement of the stitch piers will depend on conditions along the stitch pier alignment. If stitch piers are recommended, the lateral load on the stitch piers may be simulated by an equivalent fluid pressure of 85 pounds per cubic foot acting over 2 pier diameters. Passive soil resistance of 400 pounds per cubic foot acting over two pier diameters may be assumed in residual soil and bedrock. If stitch piers are recommended, we anticipate a pier diameter of 12 to 16 inches, a center-to-center spacing of 3 to 4 feet, and a total of six or seven stitch piers so that the stitch piers will extend out from the ends of the level-spreader at about 30 degrees. The depth of embedment of the stitch piers into residual soil or bedrock is expected to be approximately 1.5 times the depth of the surface soil at the pier locations.

If the mitigation measures described above are implemented, it is our opinion that the potential for soil erosion and slope instability below the level-spreader will be low. 445
Mr. Jeff Kraft Response to Review Comments Page 4 of 5
ROMIG ENGINEERS, INC.

Existing fill along the downslope side of the cul-de-sac will need to be removed and recompacted as recommended in our January 29, 2016 report. Removal and replacement of existing fill will also need to extend below the proposed bio-retention area and shallow gravel basin adjacent to the end of the cul-de-sac.

Geotechnical Comment 4:

The northern side of the cul de sac requires a cut but a retaining wall is only depicted to support a portion of the cut. Proposed final contours are not depicted to indicate the cut inclination beyond the retaining wall. Grading and wall need to be clarified around the northern edge of the cul de sac. An explanation should be provided indicating how the planned driveway for the Campbell project will be accommodated.

Proposed finished grades on the slope south of the Campbell driveway and north of the culde-sac are shown on the Site Plan on sheet C1. Based on these elevations, the length and location of the low proposed retaining wall along the north side of the cul-de-sac appears to be appropriate. It does not appear that the proposed cul-de-sac will need to be modified to accommodate the proposed driveway to the Campbell residence since they are both designed to conform to the existing western end of Monte Cresta Drive.

Geotechnical Comment 5:

The project geotechnical consultant should verify the geotechnical design parameters to be utilized for all retaining walls associated with construction of the cul de sac.

Geotechnical design parameters for retaining walls, including the proposed retaining walls along the north and south sides of the cul-de-sac, are summarized on pages 12 and 13 of our January 29, 2016 geotechnical report for the Kraft residence.

Geotechnical Comment 6:

The driveway profile (Kraft residence access) depicted on sheet C1 should be drawn to scale.

The Driveway Profile shown on sheet C1 appears to be drawn to scale.

Geotechnical Review of Revised Civil Plans
The proposed residence and the cul-de-sac for the fire truck turn-around are shown on civil plan sheets C1, C2, and C3, dated October 5, 2016, prepared by BKF Engineers. Based on our review, it is our opinion that these preliminary grading and drainage plans reflect the intent of the storm water drainage recommendations in our geotechnical report. We will consult with BKF Engineers during preparation of final grading and drainage plans for the project after planning approval is received from the City.

We make no warranty, expressed or implied, for the services we perform for this project.

Our services are performed in accordance with the geotechnical engineering principles generally accepted at this time and location.
446
Mr. Jeff Kraft Response to Review Comments Page 5 of 5
ROMIG ENGINEERS, INC.

Please call if you have questions or comments about site conditions or any of the information and responses to the City planning review comments summarized in this letter.

Very truly yours,
ROMIG ENGINEERS, INC.

Richard G. Woodard, P.E., G.E.

Copies: Addressee (4)
BKF Engineers (via email)
Attn: Mr. Christian Anzelde and Mr. Isaac Kontorovsky
RGW:PV:dr
447
Mr. Jeff Kraft
105 Scenic Drive
Redwood City, California 94062
Dear Mr. Kraft:

February 23, 2017
3614-1
RE: GEOLOGIC AND GEOTECHNICAL

UPDATE TO COMPLETE
KRAFT
APPLICATION NO. 2015-0057

RESIDENCE AND

MONTE CRESTA DRIVE CUL-DE-SAC

BELMONT, CALIFORNIA
This letter provides the geologic and geotechnical information requested by the City of Belmont Planning Commission to complete Application No. 2015-0057 for the proposed residence on your property (APN 043-165-180) and the adjacent fire truck tum-around at the current terminus of Monte Cresta Drive in Belmont, California. As you know, we performed a geotechnical investigation for the proposed residence and adjacent fire truck tum-around and presented the results in a geotechnical report dated January 29, 2016.

The geologic and geotechnical information the City requested for them to consider your application complete to be was summarized in Exhibit A, page 3 of 6, in the City's Resolution No. 2017-02, dated January 3, 2017. Our responses to Items la, lb, and le are summarized below.

Item 1 a: CEG Inspection and Evaluation -A Certified Engineering Geologist (CEG) shall inspect slopes at and below the area where construction of the bioretention area and discharge of street drainage are proposed (northwest of the proposed Kraft residence) and shall evaluate the potential for adverse impacts to slope stability associated with the proposed new drainage structures. The CEG shall inspect and update mapping (as needed) for the proposed project development site.

As part of the site investigation for Romig Engineers' January 29, 2016 report, the undersigned CEG and Geotechnical Engineer inspected the proposed work area in the Monte Cresta Drive Right-of-Way and the slopes on the Kraft property. The results of the geologic observations and site mapping were presented in our January 29, 2016 report.

On February 16, 2017, the.undersigned CEG and Geotechnical Engineer visited the proposed work area paying particular attention to the ground surface downslope of the proposed bioretention area and drainage structures. There were no indications of drainage or erosion rills, debris flow channels, soil slumps, flows, or landslides. The surface soils appeared to be relatively coarse-grained, including sand and gravel, which should facilitate water infiltration to the underlying colluvium and weathered sandstone bedrock. We also noted bedding and joints within exposed weathered bedrock and in underlying bedrock in cuts excavated along the Monte Cresta Drive Right-of-Way and downslope of the site.

The bedding and joints are variably oriented and should help facilitate water infiltration. 1390 El Camino Real, Second Floor I San Carlos, CA 94070 I (650) 591-5224 I www.romigengineers.com 448 Mr. Jeff Kraft Response to Complete Planning Application Page 2 of 5 Despite recent heavy rainfall, there was no evidence of surface soil erosion, seeps, or soil slumps on the Kraft property or in the area for the proposed fire truck turnaround, bioretention area, or drainage structures. The geologic mapping shown on the Site Geologic Map, Figure 3, in our January 29, 2016 report was judged to adequately represent existing conditions on the site and within the work area without modification.

The attached Site Plan and Cross-Sections show existing and proposed topography and subsurface conditions across the proposed bioretention area and adjacent fire truck turnaround. Based on our original site investigation and conditions observed at the site, we anticipate that sandstone bedrock is present at a depth of about 1 to 2 feet below the original ground surface. We have shown bedrock downslope of the Right-of-Way at a depth of 2 to 3 feet below the original ground surface on the attached Cross-Sections.

As shown on the Site Plan and Cross-Section AA, an excavation will be made for the fire truck turnaround that will direct the majority of the storm water runoff in the Monte Cresta Drive Right-of-Way into a gravel-filled infiltration trench. The bottom of the infiltration trench will be excavated into bedrock. We understand the storage volume of the infiltration trench was sized to accommodate runoff from a 10 year storm.

Rain water that falls on the surface of the fire truck turnaround will be collected and discharged into the bioretention basin via a bubbler. As shown on Section AA, the proposed grading is expected to remove the majority of the existing fill in the Monte Cresta Drive Right-of-Way, and the downslope side of the proposed bioretention area will be excavated into or through a thin layer of colluvium.

For improved strength, stability, and resistance to erosion along the downslope side of the bioretention basin, the basin could be moved further away from the face of the slope, and/or the surface soil along the downslope edge of the bioretention area could be removed down to bedrock and reconstructed as a keyed and benched structural fill, if needed. The extent of the remedial grading, if any, will need to be determined when conditions are exposed during excavation for the bioretention basin. For improved resistance to erosion, the downslope side of the bioretention basin could be covered with a high quality erosion control blanket.

Item 1 b: Romig Engineers Update - The Project Geotechnical Consultant shall make observations and inspect the entire length of Monte Cresta Road extension. The consultant shall make recommendations and perform additional testing and borings, if required. The consultant shall also update conclusions and recommendations regarding the feasibility of the through roadway, proposed site development and associated drainage measures after reviewing the findings of the CEG described above.

Romig Engineers performed a geologic and geotechnical investigation to address the feasibility of constructing an 1,800-foot-long Monte Cresta Drive Through Road and presented the results in a report dated June 30, 2008. Based on our site investigation, we concluded that constructing a Through Road is impractical and economically infeasible, 449
Mr. Jeff Kraft Response to Complete Planning Application Page 3 of 5 although extending Monte Cresta Drive a distance of about 750 feet to near the top of a spur ridge was feasible with proper design and construction. The City's geologic and geotechnical consultant, Cotton, Shires and Associates, Inc., agreed with the findings and conclusions summarized in our Through Road Feasibility Report and summarized their findings, conclusions, and recommendations in a Geotechnical Peer Review Letter to the City of Belmont, dated August 13, 2008.

One of the conclusions presented in Cotton, Shires and Associates' August 13, 2008 letter to the City was that they agreed with Romig Engineers' assessment "that no significant geotechnical constraints (beyond standard mitigation design) are apparently present along the first 104-foot segment of the road extension from the end of the existing roadway pavement ... ". Recommended mitigation measures for constructing the proposed fire truck turnaround were summarized in our design-level geotechnical report for your residence, dated January 29, 2016.

On February 1, 2017, the undersigned Geo technical Engineer walked the entire 1800-foot long alignment of the Monte Cresta Drive Through Road to observe current conditions.

The results of this most recent walk-through indicated that site conditions have not changed significantly since the 2008 Monte Cresta Drive Through Road Feasibility Report was prepared. The landslides and potential zones of slope instability mapped previously by Romig Engineers and the City's geologic consultant were still present. Some of the steep cut and fill slopes along the Right-of-Way, particularly north and northwest of the mapped Pdf zo�e located about 180 feet beyond the end of the proposed. fire truck turnaround, showed evidence of on-going and recent downslope soil creep and mass wasting. Several of the drainage gullies in the northern portion of the Through Road alignment, primarily north of the spur ridge located about 700 feet north of the fire truck turnaround, showed evidence of surface erosion, deepening, and enlargement.

There are considerable geologic and geotechnical concerns regarding the presence of existing active and dormant landslides, the extensive retaining walls required on both sides of the Right-of-Way to achieve the required road width, the difficulty of accessing acceptable building sites on both sides of a road extension, and control and discharge of storm water runoff beyond the large mapped landslides located north of the spur ridge about 700 feet beyond the end of the proposed fire truck turnaround. The natural drainage swales where storm water runoff is typically discharged contain deep colluvium and landslide debris that would be adversely influenced by introduction of additional concentrated storm water discharge from extension of Monte Cresta Drive further than approximately 700 feet beyond the end of the proposed fire truck turnaround.

Based on our recent observations at the site and along the Monte Cresta Drive Through Road alignment, we agree with the conclusions and recommendations in our June 30, 2008 Geologic and Geotechnical Report addressing the feasibility of the Monte Cresta Through Road, the feasibility of extending Monte Cresta Drive 104 feet beyond its current terminus, and the feasibility of extending Monte Cresta Drive up to the spur ridge about 700 feet beyond the end of the currently proposed fire truck turnaround. 450
Mr. Jeff Kraft Response to Complete Planning Application Page 4 of 5 Item 1 c: Revised Civil Engineering Plans - Civil engineering plans for street and drainage improvements shall be updated as necessary to address recommendations of the Project Geotechnical Consultant.

Our conclusions regarding the overall stability of the slope below the proposed bioretention area and storm drain system for the fire truck turnaround are summarized in our response to Item 1 a above. Based on our evaluation of site conditions, we recommend the following modifications be made to the civil engineering plans for the fire truck turnaround and associated drainage system:

1. Move the bioretention basin and gravel infiltration trench at least 1 foot further from the edge of the Monte Cresta Drive Right-of-Way. Modify finished grade of the excavation slope adjacent to the infiltration trench and bioretention area, as needed.

2. Add the following note to the civil plans: "Reconstruct slope along downslope side of bioretention area as directed in the field by the geotechnical engineer. Line slope along southern side of bioretention area with an erosion control blanket, such as North American Green 350, or equal. Slope lining shall extend at least 6 feet beyond the edge of the bioretention basin.

We make no warranty, expressed or implied, for the services we perform for this project.

Our services are performed in accordance with the geotechnical engineering principles generally accepted at this time and location.

Please call if you have questions or comments about site conditions or any of the information summarized in this letter.

Very truly yours,
ROMIG ENGINEERS, INC. �11� 'f(':RTIFI
* ENOINfER
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David F. Hoexter, C.E.G.

Richard G. Woodard, P.E., G.

Attachments: Site Plan Showing Propose Grading, Drainage and Fire Truck Turnaround Cross-Sections AA and BB
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Mr. Jeff Kraft Response to Complete Planning Application Copies: Addressee (4)
BKF Engineers (via email)
Attn: Mr. Isaac Kontorovsky and Mr. Richard Gonzalez
Hopkins & Carley (via email)
Attn: Ms. Dori Yob Kilmer
RGW:DFH:PV:dr