cc 2022 AR 08/23 camino largo residential development p21-0300 — Vista City Council, August 23, 2022 (part 5 of 6)

ENGINEER OF WORK CERTIFICATION STATEMENT
Preparer's Certification
I hereby declare that I am the Engineer in Responsible Charge of design of storm water best management practices(BMPs)for this project,and that I have exercised responsible charge over the design of the BMPs as defined in Section 6703 of the Business and Professions Code,and that the design is consistent with the PDP requirements of the City of Vista BMP Design Manual, which is a design manual for compliance with local City and regional MS4 Permit(California Regional Water Quality Control Board San Diego Region Order No. R9-2015.. 0100) requirements for storm water management.

I have read and understand that the City Engineer has adopted minimum requirements for managing urban runoff, including storm water,from land development activities, as described in the BMP Design Manual. I certify that this PDP SWQMP has been completed to the best of my ability and accurately reflects the project being proposed and the applicable BMPs proposed to minimize the potentially negative impacts of this project's land development activities on water quality. I understand and acknowledge that the plan check review of this PDP SWQMP by the City Engineer is confined to a review and does not relieve me, as the Engineer in Responsible Charge of design of storm water BMPs for this project,of my responsibilities for project design.

SWQMP PREPARED BY:

BRUCE RICE
bhA, Inc
5115 AVIENDA ENCINAS
Carlsbad, CA 92008
(760)931--8700
[email protected]
R.C.E. 60676
EXPIRES 12-31-22
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60676, Expires 12/31/22 w C 60678
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Bruce Rice E0Fcmof �
Print Name
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Paige 3 of 73

PROJECT OWNER CERTIFICATION STATEMENT
Owners Certification
This PDP SWAMP has been prepared for Camino Largo by BHA, Inc. The PDP SWQMP is intended to comply with the PDP requirements of the City of Vista BMP Design Manual, which is a design manual for compliance with local City and regional MS4 Permit(California Regional Water Quality Control Board San Diego Region Order No. 119-2015-0100) requirements for storm water management.

The undersigned, while it owns the subject property, is responsible for the implementation of the provisions of this plan.Once the undersigned transfers its interests in the property, its successor•in•interest shall bear the aforementioned responsibility to implement the best management practices(BMPs)described within this plan, including ensuring on-going operation and maintenance of structural BMPs.A signed copy of this document shall be available on the subject property into perpetuity.

OWNER DETAILS:

Kyun Tae Kim
Frank Sohaei,Trustee of the Falor Family Trust
2359 Pio Pico Drive
Carlsbad,CA 9200
(760)420-1267
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ojec Owner's Signature
Kim • Fr oh i Frank Kyun Tae a S ae
Print Name
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CITY OF VISTA STAFF REVIEW
Reviewed and Approved:

City Staff Signature: Date:

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PAGE INTENTIONALLY BLANK

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PROJECT VICINITY MAP
Project Name: Camino Largo
Permit Application Number: P21-0300
Insert Project Vicinity Map Below:
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FORM 1 - PROJECT CATEGORY DETERMINATION CHECKLIST
This form is used to assess stormwater BMP requirements applicable to the proposed project.The form is available as a stand-alone fillable checklist on the City's website and a completed copy must be included with the final SWAMP submitted to the City.The form is available at:
http://www.cityofvista.com/services/city-departments/community-development/building-planning- permits-applications/land-development-autocad-templates/storm-water-forms

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Project ID:

CHECKLIST
CITY OF VISTA CATEGORY FOR DETERMINATION OF PROJECT
C A L I F 0 R N I A
Project Name:

Project Location:

APPLICABILITY OF PERMANENT, POST-CONSTRUCTION STORMWATER BMP

REQUIREMENTS AND PROJECT TYPE DETERMINATION
Overview and Instructions
The City of Vista's (City's) Stormwater Management Program is regulated by the San Diego regional municipal stormwater permit(referred to as a Municipal Separate Storm Sewer System Permit).This permit requires that new development and redevelopment projects incorporate permanent stormwater Best Management Practices (BMPs) into the project design. The City of Vista's BMP Design Manual (formerly SUSMP Manual) discusses BMP requirements applicable to new development and redevelopment projects.

ALL STANDARD AND PRIORITY PROJECTS ARE REQUIRED TO INCORPORATE SITE DESIGN AND SOURCE CONTROL BMPS. Additional treatment control and hydromodification management BMP requirements apply to projects that meet specific criteria or thresholds. This checklist must be completed by the project applicant or proponent, and is used to determine if those additional BMPs are required.

Not all site improvements are considered "development projects"under the MS4 Permit.

Development projects are defined by the MS4 Permit as "construction, rehabilitation, redevelopment, or reconstruction of any public or private projects". Development projects are issued local permits to allow construction activities. To further clarify, this checklist applies only to new development or redevelopment activities and/or projects that have the potential to contact storm water and contribute an anthropogenic source of pollutants, or reduce the natural absorption and infiltration abilities of the land.

A project must be defined consistent with the California Environmental Quality Act (CEQA) definitions of"project."
"
CEQA requires that the project include "the whole of the action". "Whole of the Action" means the project may not be segmented or phased into small parts either onsite or offsite if the effect is to reduce the quantity of impervious area and fall below thresholds for applicability of storm water requirements. This requirement precludes "piece-mealing," which is the improper (and often artificial) separation of a project into smaller parts to avoid preparing Environmental Impact Report level documentation.

As indicated above, for the purposes of the BMP Design Manual, the "project" is the "whole of the action" which has the potential for adding or replacing or resulting in the addition or replacement of, roofs, pavement, or other impervious surfaces, thereby resulting in increased flows and storm water pollutants.

When defining the project, the following questions are considered:
• What are the project activities?
• Do they occur onsite or offsite?
• What are the limits of the project(project boundary)? • What is the whole of the action associated with the project (i.e. what is the total amount of new or

replaced impervious area considering all of the collective project components through all phases of the project)?
• Are any facilities or agreements to build facilities offsite in conjunction with providing service to the project (street-widening, utilities)?
Responses to the checklist represent an initial assessment of the proposed project conditions and impacts.

City staff will confirm this checklist based on assessment of the development application and/or project plans. Results of the checklist will classify a project as one of the following: Priority Development Project, Standard Project, or Non-development Project.

If additional information is needed while completing this checklist, please refer to the City's BMP Design Manual. Alternatively, contact City Land Development staff.

This Form is divided into 4 sections:

1. Post-Construction Stormwater Requirement Exemptions

2. Priority Development Project Determination

3. Special Consideration for Redevelopment Projects (50 Percent Rule)

4. Final Project Determination

liiLT CONSTRUCTION STORMWATER City of Vista
D
This section will determine whether your project is exempt from post- construction BMP requirements and would be classified as a Non-Development YES NO Project. See section 1.3 of the City's BMP Design Manual for further discussion. (a) Replacement of impervious surfaces that are part of a routine maintenance activity, such as (check yes if any apply): ❑ ❑ (i) Replacing roof material on an existing building
(ii) Rebuilding a structure to original design after damage from earthquake, fire or similar disaster
(iii) Restoring pavement or other surface materials affected by trenches from utility work
(iv) Resurfacing existing roads and parking lots, including slurry, overlay and restriping
(v) Routine replacement of damaged pavement, including full depth replacement, if the sole purpose is to repair the damage (vi) Constructing new sidewalk, pedestrian ramps or bike lanes on existing roads (within existing street right-of-way)
(vii) Restoring a historic building to its original historic design (viii) Routine replacement of damaged pavement, such as pothole repair
Note: Work that creates impervious surface outside of the existing impervious footprint is not considered routine maintenance.
(b) Repair or improvements to an existing building or structure that do not ❑ ❑ alter the size (check yes if any apply):
(i) Plumbing, electrical and HVAC work
(i i) Interior alterations including major interior remodels and tenant build- out within an existing commercial building
(iii) Exterior alterations that do not change the general dimensions and structural framing of the building (does not include building additions or projects where the existing building is demolished)
If you answered YES to either category (a)or(b), your project is considered a Non-Development Project, and post construction BMP requirements do not apply. Please proceed to Section 4 and check the Non- Development Project box.

If you answered NO to category (a)and (b), please proceed to Section 2.

SECTION • ' • ' " •
This section determines whether your project is a Priority Development Project(PDP) or a Standard Project. See section 1.4 of the City's BMP YES NO Design Manual for further discussion. The following eight(8)types of projects are defined as PDPs:
(a) New development projects that create 10,000 square feet or more of impervious surfaces (collectively over the entire project site). This includes ❑ ❑ commercial, industrial, residential, mixed-use, and public development projects on public or private land.
(b) Redevelopment projects that create and/or replace 5,000 square feet or more of impervious surface (collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surfaces). This ❑ ❑ includes commercial, industrial, residential, mixed-use, and public development projects on public or private land.
(c) New and redevelopment projects that create and/or replace 5,000 square feet or more of impervious surface (collectively over the entire project site), and support one or more of the following uses:
(i) Restaurants. This category is defined as a facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption (Standard Industrial Classification (SIC)code 5812). (ii) Hillside development projects. This category includes development on ❑ ❑ any natural slope that is twenty-five percent or greater. (iii) Parking lots. This category is defined as a land area or facility for the temporary parking or storage of motor vehicles used personally, for business, or for commerce.
(iv) Streets, roads, highways, freeways, and driveways. This category is defined as any paved impervious surface used for the transportation of automobiles, trucks, motorcycles, and other vehicles.

(d) New or redevelopment projects that create and/or replace 2,500 square feet or more of impervious surface (collectively over the entire project site), and ❑ ❑ discharge directly to an Environmentally Sensitive Area (ESA). "Discharging directly to" includes flow that is conveyed overland a distance of 200 feet or less from the project to the ESA, or conveyed in a pipe or open channel any distance as an isolated flow from the project to the ESA(i.e. not commingled with flows from adjacent lands).

Note: ESAs are areas that include but are not limited to all Clean Water Act Section 303(d) impaired water bodies; State Water Quality Protected Areas; water bodies designated with the RARE beneficial use by the State Water Board and San Diego Water Board; and any other equivalent environmentally sensitive areas which have been identified by the City.

For projects adjacent to an ESA, but not discharging to an ESA, the 2,500 sq-ft threshold does not apply as long as the project does not physically disturb the ESA and the ESA is upstream of the project.

There are no Areas of Special Biological Significance (ASBS) or State Water Quality Protected Areas in the City's jurisdiction. The ESAs within the City's boundaries which include 303(d)-listed impairments and RARE beneficial use designations are listed below:
• Agua Hedionda Creek
• Buena Creek
• Buena Vista Creek
• Loma Alta Creek
(e) New development projects, or redevelopment projects that create and/or ❑ ❑ replace 5,000 square feet or more of impervious surface, that support one or more of the following uses:
(i) Automotive repair shops. This category is defined as a facility that is categorized in any one of the following SIC codes: 5013, 5014, 5541, 7532-7534, or 7536-7539.
(i i) Retail gasoline outlets.This category includes Retail gasoline outlets that meet the following criteria: (a) 5,000 square feet or more or (b) a projected Average Daily Traffic of 100 or more vehicles per day. (f) New or redevelopment projects that result in the disturbance of one or more ❑ ❑ acres of land and are expected to generate pollutants post construction. This means any activity that moves soils or substantially alters the pre-existing vegetated or man-made cover of any land. This includes, but is not limited to the following:
(i) Grading, digging, cutting, scraping, stockpiling, pavement removal, and exterior construction;
(i i) Substantial removal of vegetation where soils are disturbed including but not limited to removal by clearing or grubbing; or
(iii) Any activity which bares soil or rock or involves streambed alterations or the diversion or piping of any watercourse.

If you answered YES to any of the categories above (a-f), your project is considered a PDP. Please proceed to section 3 and check the Priority Development Project Box in Section 4.

If you answer NO to all categories, then your project is considered a Standard Project. Please proceed to Section 4 and check the Standard Project Box.

City of Vista
. . + � . . .

7. This section determines additional considerations required for Redevelopment YES NO PDPs. See section 1.7 of the City's BMP Design Manual for further discussion.

Will redevelopment result in the creation or replacement of impervious surface in ❑ ❑ an amount of more than 50 percent of the surface area of the previously existing development? See clarification on calculation of the ratio of impervious surface below.

These requirements for managing storm water on an entire redevelopment project site are commonly referred to as the "50 Percent Rule". For the purpose of calculating the ratio, the surface area of the previously existing development shall be the area of impervious surface within the previously existing development. The following steps shall be followed to estimate the area that requires treatment to satisfy the MS4 Permit requirements:

1. How much total impervious area currently exists on the site?

2. How much existing impervious area will be replaced with new impervious area?

3. How much new impervious area will be created in areas that are pervious in the existing condition?

4. Total created and/or replaced impervious surface = Step 2 + Step 3.

5. 50 Percent Rule Test: Is step 4 more than 50 Percent of Step 1? If yes, treat all impervious surface on the site (including existing impervious surface not being replaced or added). If no, then treat only Step 4 impervious surface and any area that comingles with created and/or replaced impervious surface area.

Note: Step 2 and Step 3 must not overlap, as it is fundamentally not possible for a given area to be both "replaced" and "created" at the same time. Also activities that occur as routine maintenance (see Section 1 of this form)shall not be included in Step 2 and Step 3 calculation.

For example, a 10,000 square foot development proposes replacement of 4,000 square feet of impervious area. The treated area is less than 50 percent of the total development area and only the 4,000 square foot area is required to be treated.

If you answered YES, then you must implement the PDP requirements for all impervious surfaces across the entire site. Please proceed to Section 4 and check the box under PDP indicating that the Project Is a Redevelopment Project Subject to the 50 Percent Rule.

If you answered NO, then you are only required to treat impervious surfaces that are replaced or created.

Please proceed to section 4 and check the box under PDP indicating this is Not a Redevelopment Project Subject to the 50 Percent Rule.

► ECTION 4 — FINAL "PROJECT •
BASED ON THE INFORMATION PROVIDED IN SECTIONS 1-3, THIS PROJECT IS DETERMINED TO BE A:
❑ PRIORITY DEVELOPMENT PROJECT. PRIORITY REQUIREMENTS APPLY AND A STORM

WATER QUALITY MANAGEMENT PLAN (SWAMP) MUST BE SUBMITTED AT THE TIME OF APPLICATION.
❑ THIS IS A REDEVELOPMENT PROJECT SUBJECT TO THE 50 PERCENT RULE. ❑ THIS IS NOT A REDEVELOPEMNT PROJECT SUBJECT TO THE 50 PERCENT RULE. ❑ STANDARD PROJECT. STANDARD REQUIREMENTS APPLY AND APPLICABLE SECTIONS

OF A STORM WATER QUALITY MANAGEMENT PLAN (SWQMP) MUST BE SUBMITTED AT THE TIME OF APPLICATION.
❑ NON DEVELOPMENT PROJECT.

Applicant Information and Signature Box City use only Address: APN(s) Concur: Yes No
Applicant Name: Applicant Title: By:

Date:

Applicant Sign to Date:
/fyJ�zp Land Dev#:

Supporting discussion for this checklist, as well as BMP requirements for Priority Development Projects and Standard Projects, is provided in the City of Vista BMP Design Manual.

FORM 2 - PROJECT OVERVIEW

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Project Name Camino Largo
Project Address 2123 N. Santa Fe Ave,Vista, CA 92084 Assessor's Parcel Number(s) (APN(s)) 159-240-07
Permit Application Number P21-0300
Watershed (select one checkbox, use webpage below to determine watershed) http://www.cityofvista.com/services/city-departments/community-development/building-planning- permits-applications/land-development-autocad-templates/storm-water-forms San Luis Rey ❑X Lower San Luis Rey—Mission, 903.11 Carlsbad ❑ Loma Alta—Loma Alta, 904.10
❑ Buena Vista— El Salto, 904.21
❑ Buena Vista—Vista, 904.22
❑ Agua Hedionda—Los Monos, 904.31
❑ Agua Hedionda—Buena, 904.32
❑ San Marcos—Batiquitos, 904.51
Parcel Area
(total area of Assessor's Parcel(s) associated 9.301 Acres ( 405,137 Square Feet) with the project)
Area to be Disturbed by the Project
(Project Area) 8.864 Acres ( 386,127 Square Feet) Project Proposed Impervious Area
(subset of Project Area) 4.597 Acres ( 200,222 Square Feet) Project Proposed Pervious Area
(subset of Project Area) 4.267 Acres ( 185,905 Square Feet) NOTE: Proposed Impervious Area + Proposed Pervious Area =Area to be Disturbed by the Project.

This may be less than the Parcel Area.

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Form 2, Page 2 of 11

DESCRIPTION OF EXISTING SITE CONDITIONS
Current Status of the Site (select all that apply and describe below):
❑ Existing development
❑ Previously graded but not built out
❑ Demolition completed without new construction
❑X Agricultural or other non-impervious use
❑X Vacant, undeveloped/natural
Describe:

In the existing condition, there is a nursery with greenhouse facilities, including dirt roadways and various storage structures. Less than 5% of the property site is impervious. The remaining existing property is vacant.

The site is surrounded by undeveloped lands and single family residential homes.

Existing Land Cover Includes (select all that apply and describe below):
❑X Vegetative Cover 9.301 Acres ( 405,137 Square Feet) ❑ Non-Vegetated Pervious Areas Acres ( Square Feet) ❑ Impervious Areas Acres ( Square Feet)
Describe:

In the existing condition, less than 5% of the property site is impervious. Site terrain continues to support a modest growth of native grass. Currently there is a nursery on site.

Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
❑ NRCS Type A
❑ NRCS Type B
❑X NRCS Type C
❑X NRCS Type D
Approximate Depth to Groundwater(GW):
❑ GW Depth 20 feet
According to the Percolation Data provided by Vinje & Middleton Engineering, Inc. dated August 16, 2016, ground water was not encountered at depths greater than 20 feet in Boring A. Groundwater was encountered at 13.5 feet in Boring B. See References for full infiltration testing report.

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Existing Natural Hydrologic Features (select all that apply and describe in next section):
❑X Drainage ditch/Swale/Waterway
❑ Seeps
❑ Springs
❑ Wetlands
❑ None
The existing topography of the project site varies between 8% and 50% in slope, and encompasses a ridge line that tops out at elevation 362.0. The lowest relative elevation within the subject property is 294.0. The existing ridge line divides the site into two separate basins that drain towards POC-1 and POC-2. All existing storm water runoff on the west side of the ridge line flows southerly towards POC-1 on the surface, and ultimately flows south across Camino Largo toward a small stream that feeds Guajome Lake. All existing storm water runoff on the north side of the ridge line, POC-2,flows westerly on the surface until discharging southerly over the top of the paved private road, and into a natural swale. A small amount of ponding occurs before the runoff crests over the road.

Additionally, there is a significant amount of offsite run-on from the hillside to the northeast of the project site.

This run-on flows to the same discharge point as POC-2. All drainage enters an existing stream bed to the south of Camino Largo, eventually joining at the existing culvert crossing below North Santa Fe Avenue, approximately 100 feet south of the project site.

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Form 2, Page 3 of 11

DESCRIPTION OF EXISTING SITE DRAINAGE PATTERNS
How is storm water runoff conveyed from the site?At a minimum, this description should answer:

1. Is existing site drainage conveyance natural or improved storm drain (urbanized);

2. Is runoff from offsite conveyed through the site? If yes, quantify all offsite drainage areas, design flows, and locations where offsite flows enter the project site, and summarize how such flows are conveyed through the site;

3. Provide details regarding existing project site drainage conveyance network, including any existing storm drains, concrete channels, swales, detention facilities, storm water treatment facilities, natural or constructed channels; and

4. Identify all discharge locations from the existing project site along with a summary of conveyance system size and capacity for each of the discharge locations. Provide summary of the pre-project drainage areas and design flows to each of the existing runoff discharge locations.

Describe existing site drainage patterns:

The project site is a hillside property dominated by an east-west trending ridge that rises approximately 66 feet above the lowest site terrain along North Santa Fe Avenue. The steepest project slopes descend to the north at 3:1(H:V)gradients. Site terrain continues to support a modest growth of native grass. Currently there is a nursery on the site, including greenhouse facilities, dirt roadways, and various storage structures. Less than 5% of the property site is impervious. The site is surrounded by undeveloped lands and single family residential homes.

The existing drainage area is divided into two (2) basins. Areas draining towards POC-1 sheet flows from the top of the southerly ridge and then westerly along Camino Largo until discharging to the south side of Camino Largo just before North Santa Fe Ave at POC-1. Areas draining towards POC-2 sheet flows westerly off the ridge until discharging southerly over the top of the decomposed granite private road and into a natural swale at POC-2. In Additional offsite areas northeast of the easterly boundary flows to POC-2. All drainage enters an existing stream bed to the south of Camino Largo, eventually joining at an existing culvert crossing below North Santa Fe Avenue approximately 100 feet south of the project site See Pre-Developed Condition Hydromodification Management Exhibit for pre-developed site drainage patterns.

POC-ID Drainage Area (ac) 100-Year Peak Flow
(cfs)
POC-1 4.95 7.05
POC-2 4.16 6.23
Total 9.11 13.28

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Form 2, Page 4 of 11

DESCRIPTION OF PROPOSED SITE DEVELOPMENT
Project Description/ Proposed Land Use and/or Activities:

The Camino Largo Project proposes the development of a forty six(46) lot residential subdivision with individual level building pads on 9.3 gross acres. The project also proposes the minor widening and improvement of the Camino Largo private drive, which will include paving, sidewalks with curb and gutter.

The graded site will include forty six(46)new residential lots with driveways and landscaping areas along five (5)streets north of Camino Largo. Approximately 53% of the property will be impervious. Biofiltration basins are proposed for the two main drainage basins for POC-1 and POC-2. Proposed grading has been minimized as much as possible to maintain existing slope and drainage patterns.

The disturbed area is 7.86 acres; the existing site is 0% impervious pre-development and 53% impervious post- development. Two (2) Points of Compliance (POC) have been identified in the southwestern and southeastern corner of the project site, as shown on the DMA Exhibit. POC-1 is the existing culvert underneath North Santa Fe Avenue and POC-2 is the existing swale located south of the existing cul-de-sac on Camino Largo.

Drainage patterns reflected on the DMA Exhibit will slightly increase the acreage draining to POC-1 and POC-

2. Both POCs include new impervious contributing area and are subject to Hydromodification Plan (HMP) compliance.

List/describe proposed impervious features of the project(e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features):

The project also proposes the minor widening and improvement of the Camino Largo private drive, which will include paving, sidewalks with curb and gutter. The graded site will include forty six(46) new residential lots with driveways and landscaping areas along five (5)streets north of Camino Largo. Approximately 53% of the property will be impervious.

List/describe proposed pervious features of the project (e.g., landscape areas):

The proposed pervious features of the project will include landscape areas in the parkways of the private streets and around the single family residences and the associated grading of the proposed pads.

Does the project include grading and changes to site topography? ❑X Yes
❑ No
Describe:

Project grading will occur on approximately 8.86 acres of the project. Proposed grading has been minimized as much as possible and avoids the steep slope areas. This maintains existing slope and drainage patterns to the fullest extent possible. Post-development site flow will mimic pre-developed drainage conditions, and will discharge from the site at below historical flow rates (see Preliminary Hydrology and Hydraulic Report for discussion and calculations). Impervious surfaces have been minimized where feasible. Due to minimized grading, some areas remain undisturbed on the project site.

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Form 2, Page 5 of 11

DESCRIPTION OF PROPOSED SITE DRAINAGE PATTERNS
Does the project include changes to site drainage (e.g., installation of new storm water conveyance systems)?
❑ Yes
❑ No
If yes, provide details regarding the proposed project site drainage conveyance network, including storm drains, concrete channels, swales, detention facilities, storm water treatment facilities, natural or constructed channels, and the method for conveying offsite flows through or around the proposed project site. Identify all discharge locations from the proposed project site along with a summary of the conveyance system size and capacity for each of the discharge locations. Provide a summary of pre-and post-project drainage areas and design flows to each of the runoff discharge locations. Reference the drainage study for detailed calculations.

Describe proposed site drainage patterns:

The project also proposes drainage improvements consisting of concrete brow ditches, storm drain pipes, catch basins, and biofiltration basins to maintain the pre-developed runoff characteristics.

Proposed grading has been minimized as much as possible and avoids the steep slope areas. This maintains existing slope and drainage patterns to the fullest extent possible.

POC-1
There is one (1) biofiltration basin which will outlet into an existing storm drain along-side North Santa Fe Avenue south of Camino Largo and discharge from the site at POC-1.

POC-2
There is one (1) biofiltration basin which outlets via a storm drain into a natural swale at POC-2.

Additional offsite areas along the easterly boundary and towards the northeast is diverted around the development via drainage channels and rip rap,to discharge as historically over Camino Largo and sheet flows into a natural swale.

Rip rap energy dissipaters are proposed at storm drain outlets to reduce flow velocities. Post- development site flow will mimic existing drainage conditions, and will discharge from the site at below historical flow rates. The Homeowners Association will maintain the private road, storm drain system, and biofiltration basins.

POC-ID Drainage Area (ac) Undetained 100- Detained 100-Year Year Peak Flow (cfs) Peak Flow (cfs)
POC-1 4.85 21.29 6.96
POC-2 5.33 19.17 6.21

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Form 2, Page 6 of 11

POTENTIAL POLLUTANT SOURCE AREAS
Identify whether any of the following features, activities, and/or pollutant source areas will be present.

Select all Pollutant Source Areas that apply and include them on the DMA Exhibit. Source control BMPs must be identified for each of these areas in Form 3 of this SWAMP:
❑X On-site storm drain inlets
❑ Sump pumps or French drains
❑ Interior or sub-surface parking garages
❑X Need for future indoor&structural pest control
❑X Landscape/outdoor pesticide use
❑ Pools, spas, ponds, decorative fountains, or other water features ❑ Food preparation and/or service
❑ Refuse/trash collection areas
❑ Industrial processes
❑ Outdoor storage of equipment, chemicals, or materials ❑ Vehicle and equipment cleaning
❑ Vehicle/equipment repair and maintenance
❑ Fuel dispensing areas
❑ Loading docks
❑ Fire sprinkler test and relief point
❑ Miscellaneous drain or wash down areas
❑X Plazas, sidewalks, and parking lots
Describe:

Prohibitive dumping placards and/or signage will be provided at storm drain inlets and catch basins.

Pest-resistant or well-adapted plant varieties such as drought tolerant and/or native plants will be planted in landscape areas.

Flow reducers or shutoff valves triggered by a pressure drop to control water loss will be used in the event of broken sprinkler heads or lines.

Sidewalk area along the streets will drain to the curb and gutter and then downstream into biofiltration areas for treatment.

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Form 2, Page 7 of 11

IDENTIFICATION AND NARRATIVE OF RECEIVING WATER AND POLLUTANTS OF CONCERN Describe flow path of storm water from the project site discharge location(s), through urban storm conveyance systems as applicable, to receiving creeks, rivers, and lagoons as applicable, and ultimate discharge to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable):

List any 303(d) impaired water bodies within the path of storm water from the project site to the Pacific Ocean (or bay, lagoon, lake or reservoir, as applicable), identify the pollutant(s)/stressor(s) causing impairment, and identify any TMDLs and/or Highest Priority Pollutants from the WQIP for the impaired water bodies:

TMDLs/WQIP Highest Priority
303(d) Impaired Water Body Pollutant(s)/Stressor(s) Pollutant Guajome Lake (903.11) Eutrophic
Lower San Luis Rey River(903.11 Benthic Community Effects Chloride
Enterococcus
Fecal Coliform
Phosphorus
Selenium
Sulfates
Total Dissolved Solids
Total Nitrogen as N
Toxicity
Identification of Project Site Pollutants*
*Identification of project site pollutants is only required if flow-thru treatment BMPs are implemented onsite in lieu of retention or biofiltration BMPs (note the project must also participate in an alternative compliance program unless prior lawful approval to meet earlier PDP requirements is demonstrated) Identify pollutants expected from the project site based on all proposed use(s) of the site (see BMP Design Manual Appendix B.6):

Not Applicable to the Expected from the Also a Receiving Water Pollutant Project Site Project Site Pollutant of Concern Sediment ❑ ❑ ❑
Nutrients ❑ ❑ ❑
Heavy Metals ❑
Organic Compounds ❑

Page 17 of 73 ends

Trash & Debris
Oxygen Demanding ❑ ❑ ❑
Substances
Oil &Grease
Bacteria &Viruses
Pesticides

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Form 2, Page 8 of 11

HYDROMODIFICATION MANAGEMENT REQUIREMENTS
Do hydromodification management requirements apply(see Section 1.6 of the BMP Design Manual; select one box and describe below)?
❑X Yes, hydromodification management flow control structural BMPs required. ❑ No, the project will discharge runoff directly to existing underground storm drains discharging directly to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean. ❑ No, the project will discharge runoff directly to conveyance channels whose bed and bank are concrete-lined all the way from the point of discharge to water storage reservoirs, lakes, enclosed embayments, or the Pacific Ocean.
❑ No, the project will discharge runoff directly to an area identified as appropriate for an exemption by the WMAA for the watershed in which the project resides.

Describe:

The biofiltration facilities were modeled using EPA SWMM version 5.1.The SWMM model uses continuous simulation modeling to determine the minimum required hydromodification management volumes for each proposed biofiltration basin.

POC-1
There is one (1) biofiltration basin which will outlet into an existing storm drain along-side North Santa Fe Avenue south of Camino Largo and discharge from the site at POC-1.

POC-2
There is one (1) biofiltration basin which outlets via a storm drain into a natural swale at POC-2.

Page 19 of 73 ends

Form 2, Page 9 of 11

CRITICAL COARSE SEDIMENT YIELD AREAS
*This section only required if hydromodification management requirements apply Based on the maps provided within the WMAA, do potential critical coarse sediment yield areas exist within the project drainage boundaries (select all that apply and describe below)?Additional signed and stamped reports must be provided to document any exemption from coarse sediment yield requirements.
❑ Yes
❑X No, No critical coarse sediment yield areas to be protected based on WMAA maps If yes, have any of the optional analyses presented in Section 6.2 of the BMP Design Manual been performed?
❑ 6.2.1 Verification of Geomorphic Landscape Units (GLUs) Onsite ❑6.2.2 Downstream Systems Sensitivity to Coarse Sediment ❑6.2.3 Optional Additional Analysis of Potential Critical Coarse Sediment Yield Areas Onsite ❑No optional analyses performed,the project will avoid critical coarse sediment yield areas identified based on WMAA maps
If optional analyses were performed, what is the final result? ❑No critical coarse sediment yield areas to be protected based on verification of GLUs onsite ❑Critical coarse sediment yield areas exist but additional analysis has determined that protection is not required. Documentation attached in Attachment 2.13 of the SWAMP. ❑Critical coarse sediment yield areas exist and require protection. The project will implement management measures described in Sections 6.2.4 and 6.2.5 as applicable, and the areas are identified on the SWAMP Exhibit.

Describe:

Page 20 of 73 ends

Form 2, Page 10 of 11

FLOW CONTROL FOR POST-PROJECT RUNOFF
*This section only required if hydromodification management requirements apply List and describe point(s) of compliance for hydromodification management flow control (see Section

6.3.1). Identify each point of compliance for flow control on the Hydromodification Management Exhibit in Attachment 2A.

Has a geomorphic assessment been performed for the receiving channel(s)? ❑ No, the low flow threshold is 0.1Q2 (default low flow threshold) ❑ Yes,the result is the low flow threshold is 0.1Q2
❑ Yes,the result is the low flow threshold is 0.3Q2
❑x Yes,the result is the low flow threshold is 0.5Q2
If a geomorphic assessment has been performed, provide the report.

Hydromodification Screening for Camino Largo prepared by Chang Consultants, Date August 6, 2021.

Discussion/Additional Information: (optional)

Page 21 of 73 ends

Form 2, Page 11 of 11

OTHER SITE REQUIREMENTS AND CONSTRAINTS
When applicable, list other site requirements or constraints that will influence storm water management design, such as zoning requirements including setbacks and open space, or local codes governing minimum street width, sidewalk construction, allowable pavement types, and drainage requirements.

The site topography contains natural channels and low points where runoff would historically gather before flowing off-site. The proposed on-site grading follows the same general topography, with storm drain features located in those historically low areas to safely convey runoff off the site.

Optional Additional Information or Continuation of Previous Sections As Needed This space provided for additional information or continuation of information from previous sections as needed.

Page 22 of 73 ends

FORM 3 - SOURCE CONTROL BMPS FOR ALL DEVELOPMENT PROJECTS

Page 1 of 4 ends

PROJECT IDENTIFICATION &SOURCE CONTROLS
Project Name: Camino Largo
Permit Application Number: P21-0300
All development projects must implement source control BMPs SC-1 through SC-6, unless justification is provided by qualified design professional See Chapter 4 and Appendix E of the Model BMP Design Manual for information to implement source control BMPs shown in this checklist.

Answer each category below pursuant to the following, and provide description. • "Yes" means the project will implement the source control BMP as described in Chapter 4 and/or Appendix E of the Model BMP Design Manual.
• "No" means the BMP is applicable to the project but it is not feasible to implement. • "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is addressed by the BMP (e.g., the project has no outdoor materials storage areas).

Source Control Requirement Applied?
SC-1 Prevention of Illicit Discharges into the MS4 ❑X Yes I ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Acknowledge that an illicit discharge is any discharge to the MS4 that is not composed entirely of wash water.

Provide educational materials to prevent illicit discharges as a component of the Operation and Maintenance Plan (O&M Plan).

SC-2 Storm Drain Stenciling or Signage ❑X Yes ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Prohibitive dumping placards and/or signage will be provided at storm drain inlets and catch basins.

SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, ❑ Yes ❑ No ❑X N/A Runoff, and Wind Dispersal
Describe how source control will be implemented, or justify if not feasible:

SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, ❑ Yes ❑ No ❑X N/A Run-On, Runoff, and Wind Dispersal
Describe how source control will be implemented, or justify if not feasible:

Page 23 of 73 ends

Form 3, Page 2 of 4
Source Control Requirement Applied?
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and ❑ Yes ❑ No ❑X N/A Wind Dispersal
Describe how source control will be implemented, or justify if not feasible:

SC-6 Additional BMPs Based on Potential Sources of Runoff Pollutants Applied? (must answer for each source listed below)
a. On-site storm drain inlets ❑X Yes ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Storm drain inlets and catch basins will be labeled with "No Dumping Drains to Waterways". See DMA Exhibit. b. Sump pumps or French drains ❑ Yes ❑ No ❑X N/A Describe how source control will be implemented, or justify if not feasible:
c. Interior or sub-surface parking garages ❑ Yes ❑ No ❑X N/A Describe how source control will be implemented, or justify if not feasible:
d. Need for future indoor&structural pest control ❑X Yes ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Pest-resistant or well-adapted plant varieties such as drought tolerant and/or native plants will be planted in landscape areas. Integrated Pest Management(IPM)educational materials will be distributed to future occupants as a component of the O&M Plan that address physical pest elimination techniques such as relying on natural enemies to consume pests, weeding, pruning, and etc. e. Landscape/outdoor pesticide use ❑X Yes I ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Irrigation systems will be designed for the specific water requirements of each landscape area. Landscaping will be designed to minimize irrigation and runoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to storm water pollution. Flow reducers or shutoff valves triggered by a pressure drop to control water loss in the event of broken sprinkler heads or lines will be used. Water conservation educational materials will also be provided for future occupants.

Page 24 of 73 ends

Form 3, Page 3 of 4
Source Control Requirement Applied?
f. Pools, spas, ponds, decorative fountains, or other water features ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
g. Food preparation and/or service ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
h. Refuse/trash collection areas ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
i. Industrial processes ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
j. Outdoor storage of equipment, chemicals, or materials ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
k. Vehicle and equipment cleaning ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:

I. Vehicle/equipment repair and maintenance ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
m. Fuel dispensing areas ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:

Page 25 of 73 ends

Form 3, Page 4 of 4
n. Loading docks ❑ Yes ❑ No ❑X N/A Describe how source control will be implemented, or justify if not feasible:
o. Fire sprinkler test water and relief point ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
p. Miscellaneous drain or wash down areas ❑ Yes ❑ No 0 N/A Describe how source control will be implemented, or justify if not feasible:
q. Plaza, sidewalks, parking lots ❑X Yes ❑ No ❑ N/A Describe how source control will be implemented, or justify if not feasible:

Sidewalk area along the streets will drain to the curb and gutter and then downstream into biofiltration areas for treatment.

Discussion/justification if SC-6 not implemented. Clearly identify which sources of runoff pollutants are discussed.Justification must be provided for all "No" answers shown above.

Page 26 of 73 ends

FORM 4 - SITE DESIGN BMPS FOR ALL DEVELOPMENT PROJECTS

Page 1 of 2 ends

PROJECT IDENTIFICATION
Project Name: Camino Largo
Permit Application Number: P21-0300
All development projects must implement site design BMPs SD-1 through SD-8, unless justification is provided by qualified design professional. See Chapter 4 and Appendix E of the Model BMP Design Manual for information to implement site design BMPs shown in this checklist.

Answer each category below pursuant to the following, and provide description. • "Yes" means the project will implement the site design BMP as described in Chapter 4 and/or Appendix E of the Model BMP Design Manual.
• "No" means the BMP is applicable to the project but it is not feasible to implement. • "N/A" means the BMP is not applicable at the project site because the project does not include the feature that is addressed by the BMP (e.g.,the project site has no existing natural areas to conserve).

Site Design Requirement Applied?
SD-1 Maintain Natural Drainage Pathways and Hydrologic Features ❑ ❑ ❑X Yes No N/A
Describe how site design will be implemented, or justify if not feasible:

A proposed storm drain pipe underneath Camino Largo will be constructed to maintain the drainage stream at POC-2. Additionally, flows draining towards POC-1 will discharge at the historical point of discharge.

SD-2 Conserve Natural Areas, Soils, and Vegetation ❑X Yes I ❑ No ❑ N/A Describe how site design will be implemented, or justify if not feasible:

Steep natural areas located to the north of the basins draining towards POC-1 and POC-2 will be preserved where feasible. See DMA Exhibit for location of undisturbed areas. Soil disturbance is minimized where feasible.

SD-3 Minimize Impervious Area ❑X Yes ❑ No ❑ N/A Describe how site design will be implemented, or justify if not feasible:

Impervious areas have been reduced where feasible.

SD-4 Minimize Soil Compaction ❑X Yes ❑ No ❑ N/A Describe how site design will be implemented, or justify if not feasible:

Soil compaction will be minimized in natural landscape areas. Disturbed slope soils will also be amended and aerated.

Page 27 of 73 ends

Form 4, Page 2 of 2
SD-5 Impervious Area Dispersion ❑ Yes I ❑ No 0 N/A Describe how site design will be implemented, or justify if not feasible:

Landscape will effectively receive and infiltrate, and treat runoff from impervious areas. Roof drains will be directed to landscape areas where feasible prior to discharging to storm water conveyance systems.

SD-6 Runoff Collection ❑ Yes I ❑ No 0 N/A Describe how site design will be implemented, or justify if not feasible:

SD-7 Landscaping with Native or Drought Tolerant Species ❑X Yes ❑ No ❑ N/A Describe how site design will be implemented, or justify if not feasible:

Landscape design and plant palette will be selected that minimizes required resources (irrigation, fertilizers and pesticides). Native plants require less fertilizer and pesticide use because they are already adapted to local rainfall patterns and soils conditions.

SD-8 Harvest and Use of Precipitation ❑Yes ❑ No 0 N/A Note: Worksheet 8.3-1, "Harvest and Use Feasibility"must be included in this section of the SWQMP.

Describe how site design will be implemented, or justify if not feasible:

See Worksheet 8.3-1, "Harvest and Use Feasibility"

Page 28 of 73 ends

FORM 5 - STRUCTURAL POLLUTANT CONTROL AND

HYDROMODIFICATION MANAGEMENT BMPS

PROJECT IDENTIFICATION
Project Name: Camino Largo
Permit Application Number: P21-0300
PDP Structural BMPs
All PDPs must implement structural BMPs for storm water pollutant control (see Chapter 5 of the BMP Design Manual). Selection of PDP structural BMPs for storm water pollutant control must be based on the selection process described in Chapter 5. PDPs subject to hydromodification management requirements must also implement structural BMPs for flow control for hydromodification management (see Chapter 6 of the BMP Design Manual). Both storm water pollutant control and flow control for hydromodification management can be achieved within the same structural BMP(s).

PDP structural BMPs must be verified by the local jurisdiction at the completion of construction.This may include requiring the project owner or project owner's representative and engineer of record to certify construction of the structural BMPs (see Section 1.12 of the BMP Design Manual). PDP structural BMPs must be maintained into perpetuity, and the local jurisdiction must confirm the maintenance (see Section 7 of the BMP Design Manual).

Use this form to provide narrative description of the general strategy for structural BMP implementation at the project site in the box below.Then complete the PDP structural BMP summary information sheet (page 3 of this form)for each structural BMP within the project(copy the BMP summary information page as many times as needed to provide summary information for each individual structural BMP).

Describe the general strategy for structural BMP implementation at the site.This information must describe how the steps for selecting and designing storm water pollutant control BMPs presented in Section 5.1 of the BMP Design Manual were followed, and the results (type of BMP selected). For projects requiring hydromodification flow control BMPs, indicate whether pollutant control and flow control BMPs are integrated or separate structures.

Note: Each structural pollutant control and hydromodification management BMP must be clearly identified on a site map (Attachment 1a), and described in supporting table (Attachment 1B).

A feasibility analysis was then conducted for infiltration and if infiltration is fully or partially feasible for the project's structural BMPs.The negative impacts associated with retention were identified and substantiated through completion of Worksheet C.4-1 (Form 1-8).

Since infiltration is considered infeasible, biofiltration BMPs were chosen as the type of structural BMP for DMA 1 and DMA 2.

The types of structural BMPs chosen were also based on downstream receiving waters and treatment goals. Since POC-1 is located upstream from a receiving water that is 303(d) listed for a nutrient pollutant, Nutrient Sensitive Media Design (BF-2) was selected for the Biofiltration Basins 1 and 2 to minimize the potential for export of nutrients from the media.

Page 29 of 73 ends

POC-1
There is one (1) biofiltration basin which will outlet into an existing storm drain along-side North Santa Fe Avenue south of Camino Largo and discharge from the site at POC-1.

POC-2
There is one (1) biofiltration basin which outlets via a storm drain into a natural swale at POC-2.

DISP-1 and DMIN-1
Project frontage street improvements include North Santa Fe street widening delineated by DISP-1 and DMIN-1. North Santa Fe cross section is in a full superelevation cross section,4%sloping away from the project frontage in a southeasterly direction. Therefore it is infeasible to provide any stormwater treatment or flow control without the ultimate street improvements being completed. However,the proposed sidewalk along the project frontage will be non-contiguous with the proposed curb and gutter, allowing impervious dispersion to occur effectively disconnecting the concrete sidewalk from directly draining offsite by routing runoff from the sidewalk onto the adjacent landscape areas.

Camino Largo
Project frontage street improvements include Camino Largo street widening delineated on the DMA Exhibit. Camino Largo will be improved to the centerline and another 12 feet to the south of the centerline, except where the crown of Camino Largo has been transition to the south 8 feet between Private Street—Lot F and the spillway to prevent street runoff from overflowing to the south and bypassing the BMP 2. A proposed 8 inch curb and gutter will be used between the previously mentioned crown transition to sufficiently convey street runoff into BMP 2.

Page 30 of 73 ends

FORM 6 — STORMWATER BMP MAINTENANCE MECHANISM

PROJECT IDENTIFICATION
Project Name: Camino Largo
Permit Application Number: P21-0300
Maintenance Requirements
A stormwater structural BMP operations and maintenance plan must be prepared for PDPs. A template plan is available at:
http://www.cityofvista.com/services/city-departments/community-deve lop ment/building-p Ian ning- permits-applications/land-development-autocad-templates/storm-water-forms Has a stormwater structural BMP operations and maintenance plan been prepared? ❑X Yes, included with Attachment 3A
❑ No
bhA. Inc
land planning, civil engineering, surveying
5115 Avenida Encinas, Suite L
Carlsbad, CA 92008-4387
(760) 931-8700
[INSERT PREPARER'S TITLE/COMPANY]
All projects are required to maintain designed functionality of structural BMPs in perpetuity. Privately- owned projects must record a Storm Drain Maintenance Agreement with the County of San Diego Assessor's Office. A template Storm Drain Maintenance Agreement is available at:
http://www.cityofvista.com/services/city-departments/community-development/building-planning- permits-applications/land-development-autocad-templates/storm-water-forms Has a Storm Drain Maintenance Agreement been submitted to the County? ❑X Yes, copy included with Attachment 3B
❑ No
❑ Not Applicable (e.g., city-owned property/project)

Page 31 of 73 ends

Each of the attachments indicated below should be considered for inclusion with the SWAMP. Use this ATTACHMENT 1 - POLLUTANT CONTROLS: SUPPORT DOCUMENT AND

CHECKLIST
checklist to indicate which attachments are included behind this coversheet.

Attachment Contents Checklist
Sequence
Attachment 1A Drainage Management Area (DMA) ❑X Included Exhibit
See DMA Exhibit Checklist on next page.

Attachment 1B Tabular Summary of DMAs Showing ❑X Included on DMA Exhibit in Attachment 1A DMA ID matching DMA Exhibit, DMA
Area, DMA Type, and BMPs*
❑ Included as Attachment 113
*Provide table in this Attachment OR on
DMA Exhibit in Attachment 1A
Attachment 1C Harvest and Use Feasibility Screening ❑X Included Checklist (Worksheet B.3-1)
❑ Not included because the entire project
Refer to Appendix B.3-1 of the BMP will use Infiltration BMPs Design Manual.

Attachment 1D Categorization of Infiltration Feasibility ❑X Included Condition (Worksheet C.4-1)
❑ Not included because the entire project
Refer to Appendices C and D of the BMP will use Harvest and Use BMPs Design Manual.

Attachment 1E Pollutant Control BMP Design ❑X Included Worksheets and Calculations
Refer to Appendices B and E of the BMP
Design Manual for structural pollutant
control BMP design guidelines

Page 32 of 73 ends

ATTACHMENT 1A - DMA EXHIBIT CHECKLIST
For Attachment 1A, provide map(s)for the project site,titled"DMA Exhibit."The checklist below identifies minimum elements that must be included with the DMA Exhibit. 0 Underlying hydrologic soil group
0 Approximate depth to groundwater
0 Existing natural hydrologic features (watercourses, seeps, springs, wetlands, etc.) 0 Critical coarse sediment yield areas to be protected
0 Existing topography and impervious areas
0 Existing and proposed site drainage network and storm drain structures 0 Proposed connections to offsite drainage
0 Proposed demolition
0 Proposed grading
0 Proposed impervious features
0 Proposed design features and surface treatments used to minimize imperviousness 0 Drainage management area (DMA) boundaries
DMA identification numbers (DMA ID)
0 DMA areas (square footage or acreage)
0 DMA type (Drains to BMP, Self-mitigating, De Minimis, or Self-retaining) 0 Potential pollutant source areas and corresponding required source controls (see Form 2 and Form 3 of SWAMP, BMP Design Manual Chapter 4 and Appendix E.1) 0 Proposed Structural BMPs (see Form 5 of SWAMP)

Page 33 of 73 ends

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DEEP ROUTED, DENSE,

DROUGHT TOLERANT
TYPE G-2 CATCH BASIN PLANTING SUITABLE FOR - O 5 PER D-8 WELL DRAINED SOIL - LEGEND
2 � O FREEBOARD = 12.00„ (CONJUNCTIVE USE FACILITY) 4 L(FC BASIN HEIGHT HMAx = 30.00" 6 P3" MULCH----,,,, =�
— — — PONDING DEPTH = 6.00" �— — 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR — ' ' I I O RISER INVERT HTOP = 18.00" _ _4 PEA GRAVEL
O5 *EMERGENCY WEIR INVERT = 18.00"
U R 7" GRAVEL LAYER O *LOWER SLOT INVERT = 6.00" O O O O O� = FOR V2 STORAGE 1 - 5" HIGH X 34" LONG OPENING OUTFLOW � —
7O *UPPER SLOT INVERT = 7.00"
THREE (3) 12" RCP I 6" PERFORATED PVC PIPE 1 - 4" HIGH X 10" LONG OPENING OUTLET PIPES _ ' I I I L
i CONFORMING TO ASTM D PC POLLUTANT CONTROL WSEL = 6.00" 30 ML Yk
3034 OR EQUIVALENT
IMPERMEABLE 3" DEAD STORAGE HC HYDROMODIFICATION CONTROL WSEL = 13.92" LINER* EXIST. GROUND RESTRICTER CAP TO LIMIT FLOW OUT OF V2 STORAGE AREA, LID BELOW UNDERDRAIN FC FLOOD CONTROL WSEL = 18.00"
DRAIN DOWN HOLE, d = 4.00"
BIOFILTRATION BASIN DETAIL, BMP 1 *ELEVATION MEASURED FROM BASIN SURFACE

NOT TO SCALE
*30 MILLINER NOTE: 30-MIL IMPERMEABLE LINER FOR BIORETENTION CONFORM TO THE FOLLOWING SPECIFICATIONS: SPECIFIC GRAVITY (ASTM D792): 1.2 (G/CC, MIN.); TENSILE (ASTM D882): 73 (LB/IN-WIDTH, MIN); ELONGATION AT BREAK (ASTM D882): 380 (%, MIN); MODULUS (ASTM D882):
30 (LB/IN-WIDTH, MIN.); AND TEAR STRENGTH (ASTM D1004): 8 (LB/IN, MIN); SEAM SHEAR STRENGTH (ASTM D882) 58.4 (LB/IN, MIN); SEAM PEEL STRENGTH (ASTM D882) 15 (LB/IN, IN).

SEE COLORADO LINING INTERNATIONAL PVC 30
HTTP: //WWW.COLORADOLINING.COM/PRODUCTS/PVC.PDF) OR APPROVED EQUAL.

DEEP ROUTED, DENSE,

DROUGHT TOLERANT
TYPE G-1 CATCH BASIN PLANTING SUITABLE FOR PER D-8 WELL DRAINED SOIL
LEGEND
i �? Shop 2 1O FREEBOARD = 12.00" (CONJUNCTIVE USE FACILITY) HC FC _�,• — 1
BASIN HEIGHT HMAx = 30.00"
— 3O 6 PC 3" MULCH----,,,, PONDING DEPTH = 6.00" 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR — 4 PE' ' .A GRAVEL I I O RISER INVERT HTOP = 18.00" = =I O5 *EMERGENCY WEIR INVERT = 18.00" 7" GRAVEL LAYER O *LOWER SLOT INVERT = 6.00" O O O O OQ = FOR V2 STORAGE 1 - 3" HIGH X 32" LONG OPENING OUTFLOW = 7O *UPPER SLOT INVERT = 7.00" 6" PERFORATED PVC PIPE 1 - 2" HIGH X 6" LONG OPENING TWO (2) 12" RSCP _ — CONFORMING TO ASTM DOUTLET PIPE POLLUTANT CONTROL WSEL = 6.00" 30 ML I - _i I I i , 3034 OR EQUIVALENT IMPERMEABLE 3" DEAD STORAGE HC HYDROMODIFICATION CONTROL WSEL = 6" LINER* EXIST. GROUND RESTRICTER CAP TO LIMIT FLOW OUT OF V2 STORAGE AREA, LID BELOW UNDERDRAIN FC FLOOD CONTROL WSEL = 18.00"
DRAIN DOWN HOLE, d = 3.00"
BIOFILTRATION BASIN DETAIL, BMP 2 *ELEVATION MEASURED FROM BASIN SURFACE

SEE COLORADO LINING INTERNATIONAL PVC 30
HTTP: //WWW.COLORADOLINING.COM/PRODUCTS/PVC.PDF) OR APPROVED EQUAL.

MALE NATIONAL PIPE THREAD

PVC ADAPTER CAST
IN SIDE OF RISER WALL RISER WALL
a O O O
n n n
° ° ° GRA VEL S TORA GEQR,
UNDERDRAIN ORIFICE a

THREADED FEMALE NATIONAL

PIPE THREAD PVC CAP
WITH DRILLED ORIFICE 6" FRENCH DRAIN,
PERFORATED PVC PIPE bhAinc,
d °°G Dann pDaPl�Whg, dA engheedngo surveyhg III=1 I I i 11-1 11-
11 —III—III 5115 AVENIDA ENCINAS
SUITE "L"
BOTTOM OF BASIN CARLSBAD, CA. 92008-4387 (760) 931-8700
- d d
a
a
d
a d °
a
a
d � G
6" PERFORATED PVC PIPE ° d
a
UNDERDRAIN ORIFICE d ` ° DMA EXHIBIT THREADED FEMALE NATIONAL a °
PIPE THREAD PVC CAP ° d° a CAMINO LARGO WITH DRILLED ORIFICE a d

CITY OF VISTA, CALIFORNIA
RESTRICTOR CAP DETAIL BMP 1 & 2

NOT TO SCALE
SHEET 2 OF 2
K:\Civil 3D\1154\DWG\SWMP\DMA-TSM.dwg, 12/7/2021 11:44:58 AM

ATTACHMENT 1C - HARVEST AND USE FEASIBILITY SCREENING
CHECKLIST (WORKSHEET B.3-1)

Page 34 of 73 ends

Appendix B.Storm Water Pollutant Control Hydrologic Calculations and Sizing Methods Workshect B.3-1.Harvest and Use Feasibility Screening

1.Is there a demand for harvested water(check all that apply)at the project site that is reliably present during the wet season?
❑Toilet and umal flushing
®Landscape irrigation
❑Other:

2.If there is a demand,estimate the anticipated average wet season demand over a period of 36 hours.

Guidance for planning level demand calculations for toilet/urinal flushing and landscape irrigation is provided in Section B.3.2.

Modified ETWU=2.7 x[[(0.2)<180,518)I0.9]x 0.015]=1,625 cf Total Previous Area=180,518 sf

3. Calculate the DCV using worksheet B-2,1,
DCV=7,329+4,899=12,228 of
3a.Is the 36-hour demand 3b.Is the 36-hour demand greater 3c.Is the 36-hour greater than or equal to the than 0.25DCV but less than the full demand less than DCV? DCV? 0.25DCV?
Yes / IVo a yes / �� Yes
Harvest and use appears to be Harvest and use may be feasible. Harvest and use is feasible.Conduct more detailed Conduct more detailed evaluation and considered to be evaluation and sizing sizing calculations to deterniute infeasible. calculations to confirm that feasibility.Harvest and use may only DCV can be used at an adequate be able to be used for a portion of the rate to meet drawdown criteria, site,or(optionally)the storage may need to be upsizcd to meet long term
capture targets while draining in
longer than 36 hours.

B-11 February 2016

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ATTACHMENT 1D- CATEGORIZATION OF INFILTRATION FEASIBILITY J013 0 16-190.5 Storm Water5MP
Test Site Location- Percolation Data
Camino Largo,
Vista
Infltratfon BMPType infiltration Basin
Test Method Shallow Percolation Testing(Option 2)
Factor of Safety FS=3
Drflf Date 08/10/16
Test Date 0&11I16
Equipment Type B-31 Mobile Drill Using Said stem Auger Tesl Bore Diameter 8'inch
Observation Bore Diameter 6'Inch
Groundwater Conditions Groundwater Encountered 13'5'In Deep B Wcathar Conditions Dry,Sunny,813°to 90'F
Test No. I Depth ft Percolation Rate rn 1 Infiltration Rate in hr 1 4' 2fl.00 0.16 BAISN A
la 4' 10.00 0.31
2 4' 15.00 0.23 BASIN G
2a 4' 12.U0 D.29
3 4' 30.00 0.104 BASIN B
3a 4' 34.00 0.101
BAISN A Aywtiye=15.00 mpi Average=0.24 inlhr BASIN G Average=13-60 mpi Average=0,26 inlhr BASIN B Average=32.00 mpi Average=0.103 inlhr Infiltration Rales Vary 511ghtly Due to Actual Depth of Hole In Inches Depth k Observation Dori 9 A 00016
No Groundwater Encaunrered
Clean Depth=20'1"
Da h ft Observation Boring 8 0811012018
0-3' Tan Loamy Send

3.19, Brown Sandy Clay
End @ 19'
nule;See tied I Report For USCS Soil Classifications 2460 Auto Park Way
Vlnje 8 Middleton Esoondida.CA 92029-1229
Vnje #86�f 1 Engineering,Inc. (7B0)743-1214

Page 36 of 73 ends

16-192-S BASINS A,B & G RESULTS PAGE
Paif?-Frill Infiltration hrasibilitt Scrccuivug C�itcria Wonld mfdteation of the fall design votantc be feasible from a gthvsical perspective xkithova am undesirable consequences that cannot be.teasonalily mitigated? Cr terra . 1s the estimated telia Screening Qucsuon_ Yes No ble infiltration rate beloti proposed
facility locations greater than 0.5 inches per hour?The 1 response to this Screening Question shall be based on a X comprehensive evaluation of the factors presented in.Appendix C.2 and Appendix D.

Provide basis:TEST DATA WAS COLLECTED FROM SIX S"INCH DIAMETER BORINGS DRILLED TO 4' FEET AND ONE 6" INCH BORING DRILLED TO 19' FEET WITHIN 50' FEET OF THE RESIDENTIAL STORM WATER DETENTION BASIN AREAS.SEE.-ATTACHED INFILTRATION RATE RESULTS AND TEST LOCATIONS. i4L-kXINIU11,1 INFILTRATION RATES OF = 0.31 INCHES/FIOUR AND AIINDIUII INFILTRATION RATE = 0.10 1NCFIES/HOUR WERE RECORDED. AVERAGED TESTED INFILTRATION RATES=0.24 IN/FIR IN BASIN A,0.103 IN/HR IN BASIN B&0.26 IN/HR IN BASIN G.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion of srudv/data source applicability.

Can infiltration greater than 0.5 inches pet hour be allowed without increasing risk of geotechnical hazards(slope
2 stability,groundwater mounding,utilities,of other factors) that cannot be mitigated to an acceptable level?The response to this Screening Question shall be based on a comprehensive evaluation ofthe factors presented in Appendix C.2.

Provide basis:

UNKNOW HAZARD POTENTIAL BASED ON COLLECTED FIELD DATA HAVING AVERAGE INFILTRATION RATES EQUAL TO OR LESS THAN 0.31 INCHES/HOUR.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion of study/data source applicability.

Template Date:March 29,2016 Preparation Date:
08/16116
PDP SYI QMP-Attachments

Page 37 of 73 ends

Gtlterla Se eelliag uestion Yes IVo
C.au infiltration greater than 0.5 inches per hour be allowed g
without increasing risk of groundwater contamination
3 (shallow water table,storm water pollutants or other factors) that cannot be mitigated to an acceptable level?'I'he response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.3.

Provide basis:

UNKNOW HAZARD POTENTIAL BASED ON COLLECTED FIELD DATA IL-WING AVERAGE INFILTRATION RATES EQUAL TO OR LESS THAN 0.31 INCHES/HOUR.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion of study/data source applicability.

Can infiltration greater than 0.5 inches per hour be allowed without causing potential water balance issues such as change 4 of seasonally or ephemeral streams or increased discharge of X contaminated groundwater to surface watets?The response to this Scrccning Question shall be based on a comprehensive evaluation o€the factors prcsontedinA endixC.3.

Provide basin
UNY-NL OW H.1Z ARD POTENTL-IL BASED ON COLLECTED FIELD DATA HAVING AVERAGE INFILTRATION R.,VFES EQUAL TO OR LESS TFL-�N 0.31 INCHES/HOUR.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion o€study-/data source applicability.

If all answers to rows 1-4 are"Yes"a full infiltration design is potentially feasible.

The feasibility screening category is Full Infiltration PUt.t.

Part 1 INFILTRATION,?
Result* Nally answer from row I-4 is"No",infiltration may be possible to some extent but NO would not generally be feasible or desirable to achieve a"full infiltration"design.

Proceed to Part 2
Template Date: March 29,2016 Preparation Date: f 08/16/16
PDP SVVQMP-Attachments

Page 38 of 73 ends

Fart Partial Infiltration vs.'No Infiltration Feasibth1%�Screenin�_[:riicrii- Wooki infAiratioit of water in any appreciable amount be physically feasible cvicjtj)nt anv negative consequences that cannot be reasonably mitigated?
Crate is 5ueeniur Ycs No
Do suit and geologic conditions allow for infiltration in any 5 appreciable rate or volume?The response to tl-s Screening V Question shall be based on a comprehensive evaluation of the A factors reseuted in Appendix C.2 and Appendix D.

Provide basis:TEST DATA WAS COI.LF,CTED FROM SIX S"INCH DLUMETER BORINGS DRILLED TO 4' FEET AND ONE G" INCH BORING DRILLED TO 19' FEET WITHIN 50' FEET OF TIME RESIDENTLAL STORM WATER DETENTION BASIN AREAS.SEE ATTACHED INFILTRATION RATE RESULTS ,AND TEST LOCATIONS. 1%1AXIMUM INFILTRATION RATES OF = 0.31 INCHES/HOUR AND i%1INIMUNI INFILTiATION RATE = 0.10 INCHES/HOUR WERE RECORDED, AVERAGED TESTED INFILTRATION RATES=0.24 N/HR IN BASIN A,0.103 IN/HR IN BASIN B&0.26 IN/HR IN BASIN G.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.

Can Infiltration in any appreciable quantity be allowed without increasing risk of geotechnical hazards(slope stability, 6 groundwatet mounding,utilities,or other factors)that cannot X be mitigated to att acceptable level?The response to this Screening Question shall be based on a comprehensive evaluation of the factors presented in Appendix C.2.

Provide basis:

EXISTING OR PROPOSED EARTHEN SLOPES IN EXCESS OF Y FEET WILL NOT BE DOVN1 SLOPE OF THE PROPOSED RESIDENTIAL STORM AUA'I"ER BASINS.ALL OTHER FACTORS ALAY BE l-IITIGATED.INFILTRATION BASINS WILL BE IN CLOSE PROXID-IITY TO THE EXISTING UNDERGROUND UTILITIES.THESE UTILITIES MUST BE PROTECTED FROM DATH AGE POTENTLALLY CAUSED BY THE PROPOSED BASINS.

Summarize findings of studies;prmide reference to studies,calculations,maps,data sources,etc.Provide narrative discussion of study/data source applicability and why it Nvas not feasible to mitigate loco infiltration rates.

Template Date: March 29,2016 Preparation Date:
08/16/16
PDP SWQMP o Attachments

Page 39 of 73 ends

W AAA
Cx€tena SLxeerung Queshou hTo
Can Infiltration in any appreciable quantity be allowed without 7 posing significant task for groundwater related concerns(shallow water table,stotm water pollutants or other factors)? x The response to this Screening Question shall be based on a cam rebensive evaluation of the factors presented in Appendix C.3.

Provide basis:

STABALIZED GROUNDWATER CONDIDTIONS WERE,OBSERVED AT 13.42'FEET BELOW EMSTING GRADF,IN BORING B.PROPOSED BASIN DEPTH IS 4'FEET BELOW MKISTING GRADE.

IT APPEARS THAT A INIINI.IIUM OF 10'SEPARATION TO GROUNDWATER IS NOT FEASIBLE AT BASIN B.ADDITIONALY IT SI-IOULD BE NOTED THAT THIS IS THE DRY SEASON IN SEVERE DROUGHT CONDITIONS.

GROUNDWATER WAS NOT OBSERVED NEAR BASINS A&G,AND WILL MEET A I\-IININfUM 10' SEPARATION FROM BASIN BOTTObI TO STABALIZED GROUNDWATER ELEVATION.

Summarize findings of studies;provide reference to studies,calculations,maps,data sources,ere.Provide narrative discussion of study/data source applicability and why it was not feasible to mitigate low infiltration rates.

Can infiltration be allowed without violating downstream 8 water rights?The response to this Screening Question shall he X based on a comprehensive evaluation of the factors presented in Avveridix C.3.

Provide basis:

DOWNSTREAM WATER RIGI-ITS VIOLATIONS ARE EZPFCTED TO REhLMN UNCI-LINGED AND NON EXISTING.

If all answers from row 5-8 are yes then partial infiltration design is potentially feasible.

The feasibility screening category is Partial Infiltration. NO Part 2 1
Result* If any answer from row 5-8 is no,then inflnatiou of any volume is considered to be infeasible widen the drainage area.The feasibility screening category is No INFILTRATION Iafrltratioa.

Template Date:March 29,2016 Preparation Date:
08/17/16
PDP SWQMP-Attachments

Page 40 of 73 ends

The Geotechnical Engineer certifies they completed Form 1-5 except Criteria 4&9(see Appendix C.4.3).

OOOOProfessional Geotechnical Engineer's Printed Name:

RALPH MALCOLM VINJE
Professional Geote nical Enoneei Sgn sme:

Date, - Nv.8S3
'1 f prF f'H41t�'p4
The Project Design Engineer certifies they completed Criteria 4&8(see Appendix C.4.4).

Professional Prolecl Design Engineers Printed Name:

Professional Project Design Engineefs Signed Name:

Date-
Template Date:March 29,2016 Preparation Date:

OW6116
POP 5WQMP•Attachments

Page 41 of 73 ends

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Page 42 of 73 ends

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Page 43 of 73 ends

ATTACHMENT 1E- POLLUTANT CONTROL BMP DESIGN WORKSHEETS

AND CALCULATIONS

Page 44 of 73 ends

Automated Work-sheet B.1:Calculation of Design Capture Volume (V2.0) 1 Drainagr Basiri Ill or Narnc 1 2 tintless 2 Kith Percentile 24•hr Storm Oepth 0.66 0.66 inches 3 Impervious Surfaces Not Directed to Oispersion Arra((:-0.911) 119,767 79,102 sq-ft 4 Semi-Pervious Surfaces Not Serving as Dispersion Area(C-0.30) $5,241 57,922 sq-ft 5 E:iglineered Pervious Surfaces Not Serving as Dispersion Area(C=0.10) sq-ft 6 Natural Type A Soil Not Serving as Dispersion Area (C=0.10) sq-ft 7 Natural Type B Soil Not Serving as DisPcxsion Arca(C=0.14) sq-ft 8 Natural Type C Soil Not Sctvingas DisPcxsion Urea(C=0.23) sq ft 9 Naleiral T'yl3e D Soil Not Sr.rvingrss I)islrrrson An^a(C=0.30) sq ft 10 1]nes Tributary Incorporate Dispersion,Tree Wells,and/or Rain Barrels. No No o o o o o \O No yes/no 11 Impe.mmss Surfaces Directed to Dispersion Area per SI]-B((a�0.90) sq-ft 12 Semi-Pervious Surfaces Serving as Dispersion Arca pet SD-13(0 0.30) sq-ft 13 Enpineeted Pervious Surfaces Sewing as Dispersion Area per SD-B(Ci=0.10) sq-ft 14 Natural Type A Soil Serving as Dispersion Area per SD-B(Ci=0.10) sq-ft 15 Natural Type B Soil Serving as Dispersion Area per SD-B(Ci=0.14) sq-fl 16 Naltiral Type C Soil Serving as Dispersiom Area 130r SI)F3(Ci=023) scl ft 17 NAlural T'ypr D Soil Serving as Dispersiom Area pry S I)B(C i-0.30) scl fl 18 Number of Tree Wells Proposed per SO,A i 19 Average Maturc Tree Canopy Diameter ft 20 Number of Rain Barrels Proposed pet SD-E # 21 Average Rain Bartel Size plal 22 Total Tributary Area 205,008 137,024 0 0 0 0 0 0 0 0 sq-ft 23 Initial Runoff Factor for Staridard Drainage Arras 0.65 0.65 0.00 0.00 0.00 O.()f) 0.00 0.00 0.00 0.00 urlillcss 24 Triilial Runoff Factor fox Dispetsed&Dislx-rsion Arras 0.00 0,00 0.00 0.00 0.00 0.011 0.00 0.00 0.00 0.00 unitlegs 25 lTOW Wnightml liunolf Facln 0.65 0.65 0.00 0.00 0.00 0.00 I100 0.00 0.00 0.00 umtless 26 Initial Uesign Capture Volume 7,329 4,899 0 0 ❑ 0 0 0 0 0 cubic,feet 27 Total Impervious Area Dispersed to Pervious Surface 0 0 0 0 0 0 0 0 0 0 sq-ft 28 Total Pervious Dispersion Area 0 0 0 0 0 0 0 0 0 0 sq-ft 29 Ratio of Dispersed hnpervious Area to Pervious Dispersion Are n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a ratio 30 Adjusnnent Factor for Dispersed&Dispersion Areas 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 ratio 31 Runoff Factor Aflcr Dispersion Techniques 0.65 0.65 n/a n/a 11/a n/a n/a 11/a n/a n/a tintless 32 Oesign Capture Volume After Dislersion Techniques 7,329 4,899 0 0 0 0 0 0 0 0 r-ubic-feet 33 Total Tree Well Vvhu e.Reduc horn 0 0 0 0 t] 0 0 0 !1 0 �.�rlric-feet 34 Total Rain Barrel Volume Reduction {1 ❑ 0 0 0 f] 0 0 nthir.-feet 35 Final Adjusted Runoff factor 0.65 0.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless 36 Final Effective Tributary Areal 133,255 89,066 0 ❑ 0 0 0 0 0 0 sq-ft 37 Initial Design Capture Volume Retained by Site Design E lementsl 0 0 0 ❑ 0 ❑ 1 0 0 0 0 cubiaiiect 38 Final Design Capture Volume Tributary to BMPI 7,329 4,899 0 0 0 L 1 0 0 it 0 cubk-feet No Warning Messages

Page 45 of 73 ends

Automated Worksheet B.2:Retention Requirements (V2.0)
1 Draina?e Basin rD or Name 1 2uiiitless 2 $5th Percentile Rainfall T]ep 0-06 0.(,6 inches 3 Predominant NRCS Soil Type Within BMP Location D D unitless 4 is proposed BMP location Restricted or Unrestricted for lnWtrat on Activities Restricted Restricted unitless 5 Mature of Restriction Groundwater Groundwater ilnitless G Do Minimum Retention Requirements Apply to this Project Yes Yes 1-es Yes yes/no Are I IaNtahle Strumires C1reate.r than 9 Stones Proposed? lvn No yes/no R T42y C.cot,%7hniml Fn&c'c-r PerfonTic l an Tn6ltration!Analysis? YCs yvs yes/nca 9 Design Infiltrxl.ion Rate,l�MX)TTirricndrd by Gcol.r.diniral Hnvneci No No irt/hr 10 Design Inf11t1: EOIL Rate Used To Dcterinine RLIcntion Requirements 0.000 0.000 in/hi 11 Percent of Average Annual Runoff that Must be Retained within DMA 1.5% 1.5% percentage 12 Fraction of DCV Requia Retention 0.01 0.01 ratio 13 Required Retention Volume, 73 1 49 1 1 cubic-feet Nan WArning MeugLp s

Page 46 of 73 ends

m Automated Worksheet 13,3:f3MP Performance V2.0
I Drain a Rfls1 lD or NAme 1 2 - - - s -ft 2 Dc..i i Tnfih Atimn Ra.tr.Rcentnmrndcd 0.000 0.000 - - - in lhr 3 Dmqp Capture Volume Ttibzitiry to BMIP 7,191 5,010 - - rnhie-feet 4 1s BMP Vc ctatcd or Unvc ctatcd? Vc dared Vc ctatcd unitless 5 Is BMP hn cnrrcabl Lined or Unliru:d? Lined Tined initless G Due*I3MP Have:au Underdrain? Undcrdram Underdrain unitless 7 Does BMP Utilize Standard or$ ecialized Media? Standard Standard unitless 8 Provided Surface Area 6,132 8,300 a -ft 9 Provided Surface 1'vn L'cp LI, 6 6 -1- 10 Provided Soil Media Thickness 18 18 itches 11 Provided Gravel Thickness(Total Thickness 7 7 inches 12 UndereIrain Clffset 3 3 inches 13 Diameter of Undenifain or T Tydtomod Orifice. Select Smaller} 3-00 3.00 inches 14 S ecializcd Soil Media Filtration Raw in/fir 15 5 er Azed Soil Media Pore Space for Retentiene initless 16 S eriali-zed Svil Media Pure Sp.-for Bivfiltrativn unitless 17 $ ecializcd G ravel Mcdia Pow$ acc izniticAS 18 Volume;Infiltrated aver 6 Houx Stonn 0 0 0 ti 0 0 0 0 0 0 cubic•feet 19 PonduW,Pore 5 pace Available for Retention 0.00 0.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 unitless 20 T Soil Media fore$ ace Available for Retention 0.05 0.05 0.05 0.05 0.05 0-05 0.05 0.05 0-05 0.05 unitless 2i Gravel Yore Space Available for Retention Above Underdraln 0.00 0.00 0.40 0.40 0.40 0.40 0.40 0.40 0.40 0.40 unitless 22 CInvel Pore Space I�vailahle for Retention Blow IJn tie rAnni 0.40 0-40 0.40 0.40 0.40 0-40 CI-40 0AD 0-40 0-40 unitless 23 P.ffe.e,6ve Rm nfivn D. th 2.10 2.10 0.00 0.00 0,00 0.00 0.00 0.00 0.00 0.00 inches 2-I fraction of DCV Retained qI ndepeiicte.nt of I7rawclown'fimel 0-15 0.29 0-00 0-00 0-00 0-00 0-00 000 0-00 0.00 M.io 25 Calmilated Retention Store r.Drawdwm Time 120 120 0 0 0 ❑ 0 i5 0 0 hours 26 E fficacy of Re ten tiun Processes 0-17 0.30 0-00 Ci XI 0-00 0-06 0-00 Ah"I 0-00 0.00 ratio ?" Volumc Retained hv B-NTP(Con aidenng T7rawdomn Timr,) 1,229 1-493 0 it 0 ❑ 0 0 1 0 0 rnhie-feet ?8 De8iiyp Ca tun•Volumc Remaining forBioMtra6on 5,962 i7 0 it 0 0 0 0 0 0 cubic fcxI 29 Max H dromod Flow Rat1r Chro llndcrdrain 0.3512 0.3D 1-1 0.0000 0.1i(1015 0-0000 0.0000 0-0000 0.0000 0.0000 0.0000 cfs 30 Man Sent Filtration Rat.Allawcd[iU.dcrdrain O ificc 2-47 1.83 0-00 0.00 0-00 0-00 0-00 0.00 0-00 0.00 iri/hr 31 Soil Media Filtration Rate per Specifications 5.00 5A0 5.00 5.00 5.00 5.00 5.00 5.00 5.00 5.00 in/hr 32 Soil Media FiWation Rate to he heed forSnin. 2-47 1-83 0-00 0-00 0-00 0-00 0-00 0.00 0-00 1 0.00 in/lir 33 Depth Bioftltered Over 6 Hour Storm 14.85 10.97 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 itches 34 PondmA Pore Space Available fm Biofiltratirni 1-00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 imitless 35 Soil Mcd&Porr.Space Availahlt forBiofiltra.tion 0.20 0.20 0.20 020 0.20 0.20 020 020 020 020 unitless 36 Gravel Pore Space.Available for Riofiltration Above Undeuimn 0-40 0.40 0-40 6-40 0.40 0.40 0-40 0.40 0-40 0.40 imIttless 37 Effective Dcp di of Biofiltmtion StoraAc 1120 1120 0.00 0-00 0.00 0.00 0-00 0.00 0-00 0.00 inclics 38 Dtawdown Time for Surface:Potidin 2 3 0 0 0 0 0 0 0 0 holm 39 Dzawdown Time;for Efrcc tive Biolillraticui Dc th 5 6 0 0 0 0 0 0 1 0 0 hours 40 Total Depth Bwfiltcred 26.05 22-17 0-00 0.00 0.00 0.00 0-00 0.00 0-00 0.00 inches 41 Option 1-Biofilter 1.50 DCV:Target Volume 8,943 5,276 0 0 0 0 0 0 0 0 cubic-feet 42 Option 1-Provided Biofiltration Volume 8,943 5,276 0 0 0 0 0 0 0 0 cubic-feet 13 Option 2-Store 0.75 DCV:T t Volume 4,471 2,636 0 0 0 0 0 0 0 0 cubic-feet 44 0 lion 2-Provided Store a Vohrrne. 4,471 2,63E 0 0 0 0 0 0 0 0 cubic-feet 15 Portion of Binfiltra.tion Performanre Standard SA.tiCfled 1.00 1.00 0-00 0.00] 0.00 0.00 0-00 0.00 0-00 0.00 Imtio 16 Do Site Desi a TUmiien tF and BMPs'atisfy Aninul Retention R. of remen t5? Yes; Yes - - es/no 17 0vexall Portion of Performance:Standmd$atisficd MP E ffivacy Factor 1-00 1.00 0.00 0-00 i1-00 0.i1f1 0-00 0.0f1 0-()() o.00 ratio R Deficit of I-.ffe otively'Treated Storm water tl 0 n/a n/a n/a n/a n/a n1a n/a cnbk fleet i\o Warning Messages

Page 47 of 73 ends

Page 48 of 73 ends

ATTACHMENT 2 - HYDROMODIFICATION MANAGEMENT CONTROLS:

SUPPORT DOCUMENTATION & CHECKLIST
❑ Check this box if this attachment is empty because the project is exempt from PDP hydromodification management requirements.

Each of the attachments indicated below should be considered for inclusion with the SWAMP. Use this checklist to indicate which attachments are included behind this coversheet.

Attachment Contents Checklist
Sequence
Attachment 2A Hydromodification
0 Included
Management Exhibit
See Hydromodification Management Exhibit
Checklist on the back of this Attachment cover
sheet.

Attachment 2B Management of Critical Coarse ❑X Exhibit showing project drainage boundaries Sediment Yield Areas marked on WMAA Critical Coarse Sediment Yield See Section 6.2 of the BMP Area Map
Design Manual. Analyses, as applicable, for Critical Coarse Sediment Yield Area Determination, per BMP Design Manual:
❑ 6.2.1 Verification of Geomorphic Landscape
Units Onsite
❑ 6.2.2 Downstream Systems Sensitivity to Coarse
Sediment
❑ 6.2.3 Optional Additional Analysis of Potential
Critical Coarse Sediment Yield Areas Onsite
Attachment 2C Geomorphic Assessment of ❑ Not performed Receiving Channels
0 Included
See Section 6.3.4 of the BMP
❑ Submitted as separate stand-alone document
Design Manual.

Attachment 2D Flow Control Facility Design, 0 Included including Structural BMP
Drawdown Calculations and ❑ Submitted as separate stand-alone document Overflow Design Summary
See Chapter 6 and Appendix G
of the BMP Design Manual
Attachment 2E Vector Control Plan ❑ Included
Not required because BMPs will drain in less
than 96 hours

Page 49 of 73 ends

ATTACHMENT 2A - HYDROMODIFICATION MANAGEMENT EXHIBIT
For Attachment 2A, provide map(s) for the project site, titled "Hydromodification Management Exhibit." The checklist below identifies minimum elements that must be included with the exhibit. 0 Underlying hydrologic soil group
0 Approximate depth to groundwater
0 Existing natural hydrologic features (watercourses, seeps, springs, wetlands, etc.) 0 Critical coarse sediment yield areas to be protected
0 Existing topography and impervious areas
0 Existing and proposed site drainage network and storm drain structures 0 Proposed connections to offsite drainage
0 Proposed demolition
0 Proposed grading
0 Proposed impervious features
0 Proposed design features and surface treatments used to minimize imperviousness 0 Points of Compliance for hydromodification management 0 Existing and proposed drainage boundary and drainage area to each Point of Compliance (when necessary, create separate exhibits for pre-development and post-project conditions) 0 Structural BMPs for hydromodification management(location,type, and size)

Page 50 of 73 ends

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HYDROMODIFICATION CALCULATIONS BMP MODELING FOR WATER QUALITY PURPOSES DEEP ROUTED, DENSE, ENVIRONMENTAL PROTECTION AGENCY (EPA) STORM WATER MANAGEMENT MODEL 5.1 (SWMM) CONTINUOUS SIMULATION MODELING OF BIOFILTRATION BASINS DROUGHT TOLERANT MODELS WERE PREPARED FOR THE PRE AND POST-DEVELOPED CONDITIONS AT THE SITE IN ORDER TO DETERMINE IF THE PROPOSED TYPE G-2 CATCH BASIN PLANTING SUITABLE FOR DETENTION FACILITY HAS SUFFICIENT VOLUME TO MEET CURRENT HYDROMODIFICATION MANAGEMENT PLAN (HMP) REQUIREMENTS TWO (2) BIOFILTRATION BASIN FACILITIES ARE PROPOSED FOR POLLUTANT CONTROL, HYDROMODIFICATION AND O 5 PER D-8 WELL DRAINED SOIL - _
FROM THE SAN DIEGO REGIONAL WATER QUALITY CONTROL BOARD (SDRWQCB), AS ESTABLISHED AT THE HMP DOCUMENT DATED FLOW DETENTION. TABLE 2 ILLUSTRATES THE DIMENSIONS REQUIRED FOR HMP COMPLIANCE FOR THE = LEGEND MARCH 2O11, PREPARED BY BROWN AND CALDWELL. THE CONTINUOUS SIMULATION MODEL USES 58 YEARS OF RAINFALL DATA BIOFILTRTION BASINS, BMP 1 AND BMP 2. TABLES 3 ILLUSTRATES THE ORIFICE DIMENSIONS REQUIRED FOR - _- RECORDED BY THE OCEANSIDE RAIN GAUGE (RAINFALL DATA EXISTS FROM 8/28/1951 THROUGH 5/23/2008. BIOFILTRATION BASIN. �!- S 2 7 �oQ -! 1O FREEBOARD = 12.00" (CONJUNCTIVE USE FACILITY) LOW FLOW THRESHOLD TABLE 2 - SUMMARY OF DIMENSIONS FOR BIOFILTRATION BASINS BMPs: I O- 4 77 He FIC A LOW FLOW THRESHOLD FOR 0.5Q2 VALUE WAS USED TO DETERMINE THE DIAMETER OF THE LOW FLOW ORIFICE. ,,-I- = I O BASIN HEIGHT HMAx = 30.00" 3O 6 PC 3" MULCH
SWMM DEVELOPMENT Dimensions I __- I O3 PONDING DEPTH = 6.00" Biofiltration Tributary BMP Underdrain Total Riser Min.

BMP Area (Ac) Area(1) Orifice D(z) Gravel Invert Total 1 ' '- - 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR - O RISER INVERT HTOP = 18.00" STORMWATER RUNOFF FROM THE PROPOSED PROJECT SITE IS ROUTED TO TWO (2) POINTS OF COMPLIANCE. POC-1 IS LOCATED NEAR - 4" PEA GRAVEL THE SOUTHWEST CORNER OF THE PROJECT SITE. POC-1 COLLECTS RUNOFF FROM ONE ONE BASIN. POC-2 LOCATED NEAR THE ftZ (in) Depth") Elev, Surface I - - 1 „ SOUTHEAST CORNER OF THE PROJECT SITE. POC-2 COLLECTS RUNOFF FROM ONE ONSITE BASIN AND ONE OFFSITE BASIN. THE INPUT BMP 1 1 4.706 1 6,147 1 4.00 1 7 1 18 12 - O5 EMERGENCY WEIR INVERT = 18.00 DATA REQUIRED TO DEVELOP SWMM ANALYSES INCLUDE RAINFALL, WATERSHED CHARACTERISTICS, AND BMP CONFIGURATIONS. BMP 2 1 3.121 1 9,279 1 3.00 1 7 1 18 12 U R 7" GRAVEL LAYER " THE OCEANSIDE GAUGE FROM THE PROJECT CLEAN WATER WEBSITE WAS USE FOR THIS STUDY SINCE IT IS THE MOST REPRESENTATIVE O LOWER SLOT INVERT = 6.00 Notes: (1):Area ofamended soil =area of gravel =area of BMP. 0 O O O O� FOR V2 STORAGE 1 - 5" HIGH X 34" LONG OPENING OF THE SITE PRECIPITATION DUE TO ELEVATION AND PROXIMITY TO THE PROJECT SITE. EVAPORATION FOR THE SITE WAS MODELED (2): Diameter of the orifice in gravel layer with invert at bottom of layer; OUTFLOW USING AVERAGE MONTHLY VALUES FROM THE COUNTY HOURLY DATASET. THE SITE WAS MODELED WITH TYPE D HYDROLOGIC SOILS, tied with hydromod min threshold (50%Q2). L 7O `UPPER SLOT INVERT = 7.00" SOILS ARE MOSTLY ASSUMED TO BE UNCOMPACTED IN EXISTING CONDITIONS. IN DEVELOPED CONDITIONS, SOILS WITHIN THE I _ 1 - 4" HIGH X 10" LONG OPENING DEVELOPED PORTION OF THE SITE ARE ASSUMED TO BE COMPACTED, WHILE SOILS IN UNDEVELOPED AREAS ARE ASSUMED TO REMAIN (3):Total depth of gravel including 3" of saturated storage located below THREE (3) 12" RCP 2 6 PERFORATED PVC PIPE
UNCOMPACTED. BASED ON THE HMP REVIEW AND AND ANALYSIS PREPARED FOR THE CITY OF VISTA, OTHER SWMM INPUTS FOR THE (4): Depth from bottom of pond to invert of emergency weir. OUTLET PIPES _ I I III III - I CONFORMING TO ASTM D PC POLLUTANT CONTROL WSEL = 6.00" SUBAREAS ARE DISCUSSED IN THE APPENDICES OF THE SWMM STUDY, WHERE THE SELECTION OF PARAMETERS IS EXPLAINED IN 30 ML 3034 OR EQUIVALENT DETAIL. TABLE 3 - SUMMARY OF ORIFICE DIMENSION FOR BMPS: IMPERMEABLE 3" DEAD STORAGE HC HYDROMODIFICATION CONTROL WSEL = 13.92" LINER* EXIST. GROUND RESTRICTER CAP TO LIMIT FLOW OUT OF V2 STORAGE AREA, LID BELOW UNDERDRAIN Lower Slot Dimensions Upper Slot Dimensions Emergency Weir DRAIN DOWN HOLE, d = 4.00" FC FLOOD CONTROL WSEL = 18.00" HMP MODELING Biofiltration Invert Invert (#) - Riser Weir Outlet (#) - Width x Outlet
PRE-DEVELOPED AND POST-DEVELOPED CONDITIONS BMP (1) Elev, HL(z) (3) (1) Elev, HL(Z) Width x Invert Perimeter BIOFILTRATION BASIN DETAIL BMP 1 ELEVATION MEASURED FROM BASIN SURFACE THE PRE-DEVELOPED SITE WAS MODELED AS ENTIRELY PERVIOUS AS REQUIRED BY RWQCB ORDER NO. R9-2013-0001. STORM WATER Type Height(i n) Type (5) in in Height (in) Elev, Len th NOT TO SCALE RUNOFF FROM THE IMPERVIOUS ROOF AND ROAD AREAS WILL INTERCEPTED BY CATCH BASINS IN THE STREET, AND CONVEYED VIA A BMP 1 Slot 6 (2) - 34x 5 Slot 7 (1) - 10x 4 18 11.83 STORM DRAIN SYSTEM TO BIOFILTRATION BASINS. TWO (2) BIOFILTRATION BASINS WITH NO INFILTRATION ARE LOCATED WITHIN THE BMP 2 Slot 6 (2) - 32 x 3 Slot 7 (1) - 6 x 2 18 11.83 *30 MILLINER NOTE: 30-MIL IMPERMEABLE LINER FOR BIORETENTION CONFORM TO THE FOLLOWING PROJECT SITE AND ARE RESPONSIBLE FOR HANDLING WATER QUALITY REQUIREMENTS FOR POC-1 AND POC-2. Notes: (1):Shape of orifice opening in riser structure. SPECIFICATIONS: SPECIFIC GRAVITY (ASTM D792): 1.2 (G/CC, MIN.); TENSILE (ASTM D882): 73 BIOFILTRATION BASINS 1 AND 2 (BMPS 1 AND 2) ARE 6 INCHES DEEP WITH AN INTERNAL OUTLET STRUCTURE (SEE DIMENSIONS IN (2):Depth from bottom of pond to invert of lower slot or weir. (LB/IN-WIDTH, MIN); ELONGATION AT BREAK (ASTM D882): 380 (%, MIN); MODULUS (ASTM D882):

TABLE 2). FLOWS WILL THEN DISCHARGE FROM THE BASIN VIA THE OUTLET STRUCTURE OR INFILTRATE THROUGH THE BASE OF THE (3):Number of slots and slot dimensions: For examplefor BMP 1: Two 29-inch wide by 3-inch high 30 (LB/IN-WIDTH, MIN.); AND TEAR STRENGTH (ASTM D1004): 8 (LB/IN, MIN); SEAM SHEAR FACILITIES TO THE RECEIVING AMENDED SOIL AND LOW FLOW ORIFICE. THE RISER STRUCTURE WILL ACT AS A SPILLWAY SUCH THAT STRENGTH (ASTM D882) 58.4 (LB/IN, MIN); SEAM PEEL STRENGTH (ASTM D882) 15 (LB/IN, IN).

PEAK FLOWS CAN BE SAFELY DISCHARGED TO THE RECEIVING STORM DRAIN SYSTEM. BENEATH THE BASIN'S INVERT LIES THE slots at 6-inches above bottom of basin and one 10 inch wide by 3-inch high slot at 7 inches above SEE COLORADO LINING INTERNATIONAL PVC 30 PROPOSED LID BIOFILTRATION PORTION OF THE DRAINAGE FACILITIES. THIS PORTION OF THE BASIN IS COMPRISED OF A 3-INCH LAYER bottom of basin. HTTP: //WWW.COLORADOLINING.COM/PRODUCTS/PVC.PDF) OR APPROVED EQUAL.

OF MULCH, AN 18-INCH LAYER OF AMENDED SOIL (A HIGHLY SANDY, ORGANIC RICH COMPOSITE WITH AN INFILTRATION CAPACITY OF (4):Depth from bottom of pontto invert of emergency overflow weir.

AT LEAST 5 INCHES/HR) AND A 7-INCH RESERVOIR LAYER OF GRAVEL. AN UNDERDRAIN PIPE WITH LOW FLOW ORIFICE OUTLET WILL BE (5):Overflow length,the internal perimeter of the riser.

PROVIDED WITHIN THE GRAVEL LAYER TO CARRY AWAY FILTERED RUNOFF TO THE RECEIVING STORM DRAIN SYSTEM. THE BASINS WILL ALSO INCLUDE A 3-INCH SATURATED STORAGE LAYER OF GRAVEL BELOW THE UNDERDRAIN PIPE. A RISER STRUCTURE WILL BE DEEP ROUTED, DENSE, CONSTRUCTED WITHIN THE BMPS WITH A LOW FLOW ORIFICE OUTLET AND AN EMERGENCY OVERFLOW, SUCH THAT PEAK FLOWS CAN FLOW DURATION CURVE COMPARISION DROUGHT TOLERANT BE SAFELY DISCHARGED TO THE RECEIVING STORM DRAIN SYSTEM (SEE DIMENSIONS IN TABLE 2 AND 3). FLOW DURATION CURVES (FDC) WERE COMPARED AT THE PROJECT'S POCS BY EXPORTING THE HOURLY RUNOFF TIME SERIES RESULTS TYPE G-1 CATCH BASIN PLANTING SUITABLE FOR PER D-8 WELL DRAINED SOIL -
THE BIOFILTRATION BASIN WILL ALSO FULFILL WATER QUALITY REQUIREMENTS. THEREFORE, THE BASIN WILL BE DUAL PURPOSE TO FROM SWMM TO A SPREADSHEET. THE FLOW DURATION CURVES (FDC) FOR POC-1 AND POC-2 WERE COMPARED BETWEEN 109/c OF O 5 17 -
ACHIEVE THE FLOW-DURATION REQUIREMENTS SET FORTH IN THE COUNTY HMP, AS WELL AS ADDRESS THE STORM WATER QUALITY THE EXISTING CONDITION Q2 UP TO THE EXISTING CONDITION Q10. THE Q2 AND Q10 WERE DETERMINED WITH A PARTIAL DURATION _ - LEGEND REQUIREMENTS SET FORTH IN THE MS4 PERMIT AS REGIONAL POST-CONSTRUCTION TREATMENT BMPS FOR THE DEVELOPED AREA. STATISTICAL ANALYSIS OF THE RUNOFF TIME SERIES IN AN EXCEL SPREADSHEET USING THE WEIBULL PLOTTING POSITION METHOD. 711 FULL BIOFILTRATION OF THE DCV IS ACHIEVABLE BASED ON THE BASIN FOOTPRINT AND STORAGE PROVIDED ABOVE THE UNDERDRAIN 1I2. �I - NAMELY THE SURFACE PONDING, MEDIA AND AGGREGATE STORAGE. THE RANGE FROM 10% OF Q2 UP TO Q10 WAS DIVIDED INTO 100 EQUAL TIME INTERVALS; THE NUMBER OF HOURS THAT EACH FLOW I_ I Sapp 2 7 FC FREEBOARD = 12.00" (CONJUNCTIVE USE FACILITY) RATE WAS EXCEEDED WAS COUNTED FROM THE HOURLY SERIES. ADDITIONALLY, THE INTERMEDIATE PEAKS WITH A RETURN PERIOD 17 HC I O2 BASIN HEIGHT HMAx = 30.00" "I" WERE OBTAINED (Qi WITH i-3 TO 9). FOR THE PURPOSE OF THE PLOT, THE VALUES ARE PRESENTED AS PERCENTAGE OF TIME i HYDROMODIFICATION & TREATMENT CONTROL BMPS EXCEEDED FOR EACH FLOW RATE. FDC COMPARISON FOR POC-1 ARE ILLUSTRATED IN FIGURE 1 AND FIGURE 2 IN BOTH NORMAL AND I _ _ O 6 PC 3" MULCH = -I I ' DEVELOPED CONDITIONS LOGARITHMIC SCALE IN THE HMP STUDY. I I O PONDING DEPTH = 6.00 STORMWATER RUNOFF FROM THE PROPOSED PROJECT SITE IS ROUTED TO TWO (2) POINTS OF COMPLIANCE, POC-1 LOCATED NEAR THE AS CAN BE SEEN IN TABLES 4 AND 5, THE FDC FOR THE PROPOSED CONDITION WITH THE HMP FACILITIES ARE WITHIN 110% OF THE 1 I ' 1- - 18" AMENDED SOIL MIN. INFILTRATION RATE 5"/HR - >;' ' I I O RISER INVERT HTOP = 18.00" SOUTHWEST CORNER OF THE PROJECT SITE. POC-2 LOCATED NEAR THE SOUTHEAST CORNER OF THE PROJECT SITE. POC-2 COLLECTS - _4 PEA GRAVEL RUNOFF FROM ONE ONSITE BASIN AND ONE OFFSITE BASIN. CURVE FOR THE EXISTING CONDITION IN BOTH PEAK FLOW AND DURATION. THE ADDITIONAL RUNOFF VOLUME GENERATED FROM I - `EMERGENCY WEIR INVERT - 18.00" DEVELOPING THE SITE WILL BE RELEASED TO THE STORM DRAIN SYSTEM AT A FLOW RATE BELOW THE 50% Q2 LOWER THRESHOLD. - - - - - PRIOR TO DISCHARGING FROM THE PROJECT SITE, DEVELOPED ON-SITE RUNOFF FROM DMA-1 AND DMA 2 IS DRAINED TO ONSITE ADDITIONALLY, THE PROJECT WILL NOT INCREASE PEAK FLOW RATES BETWEEN THE Q2 AND THE Q10, AS SHOWN IN THE FDC PLOTS „ RECEIVING BIO FOR V2 STORAGE FILTRATION BASIN FACILITIES FOR POLLUTANT CONTROL, HYDROMODIFICATION AND FLOW DETENTION. AND ALSO IN THE PEAK FLOW TABLES. O O O O 7 GRAVEL LAYER O LOWER SLOT INVERT = 6.00 2 - 3" HIGH X 16" LONG OPENINGS
TABLE 1 - SUMMARY OF DMAS: TABLE 4 - Q2 TO Q10 COMPARISON TABLE - POC-1 OUTFLOW = 0 *UPPER SLOT INVERT = 7.00"
i _ � I 1 - 2" HIGH X 6" LONG OPENING TRIBUTARY IMPERVIOUS Post-Dev. TWO (2) 12" RCP _ 6" PERFORATED PVC PIPE POC DMA o Return Period Pre-Dev. Peak Peak Flows Reduction OUTLET PIPES _ I III l I CONFORMING TO ASTM D PC POLLUTANT CONTROL WSEL = 6.00" AREA(AC) PERCENTAGE(/) (years) Flows (cfs) (cfs) I I _ 3034 OR EQUIVALENT DMA 1 4.706 58.42% (cfs) 30 ML 1 " LF=0.1xQ2 1.318 0.987 0.331 IMPERMEABLE HC HYDROMODIFICATION CONTROL WSEL = 7.32" BMP1 0.141 0.00% * ,RESTRICTER CAP TO LIMIT FLOW 3 DEAD STORAGE 2-year 2.635 1.973 0.662 LINER EXIST. GROUND OUT OF V2 STORAGE AREA LID DMA 2 3.146 57.73% y BELOW UNDERDRAIN FC FLOOD CONTROL WSEL = 18.00" 2 BMP 2 0.213 0.00% 3-year 2.847 2.317 0.530 DRAIN DOWN HOLE, d = 3.00" BYPASS 2 1.696 0.00% 4-year 3.262 2.696 0.566 "ELEVATION MEASURED FROM BASIN SURFACE SM 1 0.201 0.00% 5-year 3.346 2.914 0.432 BIOFILTRATION BASIN DETAIL, BMP 2 S M 2 0.009 0.00%
" 6-year 3.446 3.051 0.395 SM 3 0.020 0.00% 7-year 3.648 3.132 0.517 NOT TO SCALE OFFSITE S M 4 0.155 0.00% 8-year 3.737 3.160 0.577 *30 MILLINER NOTE: 30-MIL IMPERMEABLE LINER FOR BIORETENTION CONFORM TO THE FOLLOWING DISP-1 j 0.155 j 60.05% 9-year 3.985 3.169 0.817 SPECIFICATIONS: SPECIFIC GRAVITY (ASTM D792): 1.2 (G/CC, MIN.); TENSILE (ASTM D882): 73 DMIN-1 0.124 100.00% 10-year 4.249 3.216 1.033 (LB/IN-WIDTH, MIN); ELONGATION AT BREAK (ASTM D882): 380 (%, MIN); MODULUS (ASTM D882):
30 (LB/IN-WIDTH, MIN.); AND TEAR STRENGTH (ASTM D1004): 8 (LB/IN, MIN); SEAM SHEAR STRENGTH (ASTM D882) 58.4 (LB/IN, MIN); SEAM PEEL STRENGTH (ASTM D882) 15 (LB/IN, IN).

SEE COLORADO LINING INTERNATIONAL PVC 30
TABLE 5 - Q2 TO Q10 COMPARISON TABLE - POC-2 HTTP: //WWW.COLORADOLINING.COM/PRODUCTS/PVC.PDF) OR APPROVED EQUAL.

Post-Dev.

Return Period Pre-Dev. Peak Peak Flows Reduction (years) Flows (cfs) (cfs) MALE NATIONAL PIPE THREAD (cfs)LF=0.1xQ2 1.112 0.474 0.638 PVC ADAPTER CAST 2 IN SIDE OF RISER WALL -year 2.224 0.948 1.276 RISER WALL 3-year 2.398 1.032 1.366
4-year 2.744 1.166 1.578 a 5-year 2.825 1.208 1.617 14 ° GRAVEL STORAGE LAYER 6-year 2.896 1.247 1.648 UNDERDRAIN ORIFICE �/o�o�o THREADED FEMALE NATIONAL a
7-year 3.063 1.315 1.748 PIPE THREAD PVC CAP 8-year 3.138 1.349 1.789 WITH DRILLED ORIFICE 6" FRENCH DRAIN, 9-year 3.369 1.427 1.942 PERFORATED PVC PIPE bhxinc. 10-year 3.603 1.513 2.090
III=1 I I i 11-1 11-
11 -III-III 5115 AVENIDA ENCINAS
SUITE "L"
BOTTOM OF BASIN CARLSBAD, CA. 92008-4387 (760) 931-8700
- d d
a
a
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a ° d
a
a
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6" PERFORATED PVC PIPE ° d
a
UNDERDRAIN ORIFICE d ` HMP EXHIBIT THREADED FEMALE NATIONAL a °
PIPE THREAD PVC CAP a d a a CAMINO LARGO WITH DRILLED ORIFICE a d

CITY OF VISTA, CALIFORNIA
RESTRICTOR CAP DETAIL BMP 1 & 2

NOT TO SCALE
SHEET 2 OF 2
K:\Civil 3D\1154\DWG\SWMP\HMP_TSM.dwg, 12/7/2021 11:48:35 AM

o
SUMMARY OF PRE-DEVELOPED oo 3�0 CONDITION DRAINAGE AREAS -- 005 D x � �� x 335. � �O•,3 �309 9 �? O
i
DISCHARGE LOCATION (POC) PRE-DEVELOPMENT AREA (AC) �S Z � 3 DASHED CONTOURS
POC-1 5.07 rAWl ARE APPROXIMAIT x �� w_z POC-2 4. 74 x / all oSS I / O Q 3��.9 Ix ,309 6 ��
TOTAL 9.21 ��340. 6 � � � X 339.9 34 .X �� 4
Palm DMA 2 I x JI0.5
o
967 SF 135,967.2 o O � 8.8
356. x j5/6 7777 7x 309. 4
325.

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3 ---
X 308.4
x
X 34 x 309.5
Ga e Shed - � \
j . DMA 1 745
x
215,688 SF 9 6 X 308.6 / 00 ------------------------ O 3
X 310 5
a _ o 294 6

11.3 i
I
� � 330 X 3 312.4
/
o s o
�D a
X 5000 ` X 322.
x 54 / + 325 eenhous X 3 / 305.5
295 P a I
�,9 5 Trees
joi,3 r;> 298. 4
X 315.6
�15 2 y .. LEGEND
J62. 1
oO

BASIN BOUNDARY
t
-
+ PROPERTY LINE _ rr
0 'x 3 FLOW LINE - - - �� +, x 3 8 �4' „� SOIL TYPE BOUNDARY S I g n
309� « 44,925 S1
/ �•
S.
g Pipel
\ x TO2 2
295.2 j k \ \ t
300 40' 20' 0' 40' 80' 120' 327. o
x 295.5 � x + + cone X 29 SCALE: 1" = 40' 4 5 / yN>?ar✓�F ji e .309
i x 4
yy
_• � f 2
310 x
290 X 29 .6
i.5 f
3 x 309 9bhAinc .

93. 3.4 Dana p�annhg, cM� engunaafr ng, surveying r `
x 310
V X 291.3 x 3774 -ryfr!!.� ..ri ..•�.fr �i �� r r r. ' !. -. 190 (-X- J09.6 5115 AVENIDA ENCINAS \ ! r r
r d r� f
�s . SUITE L
CARLSBAD, CA. 92008-4387
3 DMA 2 x 3>05 r
x 9 x 292 2 x 291.2 (760) 931-8700 o (V 290 I35,967 SF -
x x ��> DENSE BRUSH AND OBSCURE • ! 1� rio-lr, � � '`!7 •�! 293. � � � 31 7�3>54 I -^y r :. / � /30806 .4 x rr,`l..r� {,4t••:;:r { s !`xf,✓r�-`fir os3 CAMINO LARGO
285 -�- -� - CITY OF VISTA, CALIFORNIA PO ALE _
\f X 31
DETAIL: OFFSITE DRAINAGE
SHEET ] OF ]
K:\Civil 3D\1154\DWG\SWMP\EX_HMP_TSM.dwg, 8/25/2021 4:30:44 PM

ATTACHMENT 213- MANAGEMENT OF CRITICAL COARSE SEDIMENT

YIELD AREAS

Page 51 of 73 ends

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ATTACHMENT 2C- GEOMORPHIC ASSESSMENT

Page 53 of 73 ends

HYDROMODIFICATION SCREENING
FOR

CAMINO LARGO
September 14, 2021
Will sign and stamp upon approval
Wayne W. Chang, MS, PE 46548
changwiflaullhilm
Civil Engineering-Hydrology-Hydraulics-Sedimentation
P.O. Box 9496
Rancho Santa Fe, CA 92067
(858) 692-0760

FOR REVIEW ONLY

-TABLE OF CONTENTS -
Introduction................................................................................................................................1 Domainof Analysis...................................................................................................................2 InitialDesktop Analysis.............................................................................................................5 FieldScreening..........................................................................................................................6 Conclusion...............................................................................................................................10 Figures......................................................................................................................................11

APPENDICES
A. SCCWRP Initial Desktop Analysis
B. SCCWRP Field Screening Data

MAP POCKET
Study Area Exhibit

FOR REVIEW ONLY

INTRODUCTION
The city of Vista's June 2016, BMP Design Manual, outlines low flow thresholds for hydromodification analyses. The thresholds are based on a percentage of the pre-project 2-year flow (Q2), i.e., 0.1Q2(low flow threshold and high susceptibility to erosion), 0.3Q2 (medium flow threshold and medium susceptibility to erosion), or 0.5Q2 (high flow threshold and low susceptibility to erosion). A flow threshold of O.1Q2 represents a natural downstream receiving conveyance system with a high susceptibility to bed and/or bank erosion. This is the default value used for hydromodification analyses and will result in the most conservative (largest) on-site facility sizing. A flow threshold of 0.3Q2 or 0.5Q2 represents downstream receiving conveyance systems with a medium or low susceptibility to erosion, respectively. In order to qualify for a medium or low erosion susceptibility rating, a project must perform a channel screening analysis based on the March 2010, Hydromodification Screening Tools: Field Manual for Assessing Channel Susceptibility, developed by the Southern California Coastal Water Research Project (SCCWRP). The SCCWRP results are compared with the critical shear stress calculator results from the County of San Diego's Critical Flow Calculator spreadsheet to establish the appropriate erosion susceptibility threshold of low, medium, or high.

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This report provides a hydromodification screening analysis for the Camino Largo single-family residential project being designed by BHA, Inc. The 9.3-acre site currently supports a nursery and is located northeast of the intersection of North Santa Fe Avenue and Camino Largo in the city of Vista(see the Vicinity Map). The nursery will be redeveloped with 46 homes and private streets.

Under pre-project conditions, storm runoff within the project footprint generally sheet flows in a southerly direction towards Camino Largo, which is an unpaved private street. The runoff continues a short distance (100+ feet) south and enters an unnamed natural drainage course that 1 flows in a westerly direction along the south side of Camino Largo (see the Study Area Exhibit in the map pocket). The unnamed natural drainage course crosses North Santa Fe Avenue in an arch culvert then continues northwest over 2.3 miles to a confluence with the San Luis Rey River.

Under post-project conditions,the project runoff will be treated by one of two biofiltration basins.

Runoff from the easterly half of the project will enter a biofiltration basin at the southeast corner of the site. A proposed storm drain will convey the treated runoff out of the biofiltration basin and discharge towards the unnamed natural drainage course. Runoff from the westerly half of the project will enter a biofiltration basin at the southwest corner of the site. A proposed storm drain will convey the treated runoff out of the biofiltration basin and to the North Santa Fe Avenue culvert. The post-project runoff from both halves of the project will ultimately be conveyed away from the site by the unnamed natural drainage course similar to existing conditions.

The SCCWRP screening tool requires both office and field work to establish the vertical and lateral susceptibility of a downstream receiving channel to erosion. The vertical and lateral assessments are performed independently of each other although the lateral results can be affected by the vertical rating. A screening analysis was performed to assess the low flow threshold for the project's two points of compliance (POC), which are the first locations where the project's runoff discharges to natural conveyances. The first POC, labeled POC A, is at the outlet of the proposed storm drain from the southeast biofiltration basin. The second POC, labeled POC B, is at the outlet of the North Santa Fe Avenue culvert.

The initial step in performing the SCCWRP screening analysis is to establish the domain of analysis and the study reaches within the domain. This is followed by office and field components of the screening tool along with the associated analyses and results. The following sections cover these procedures in sequence.

DOMAIN OF ANALYSIS
SCCWRP defines an upstream and downstream domain of analysis, which establish the study limits. The County of San Diego's HMP specifies the downstream domain of analysis based on the SCCWRP criteria. The HMP indicates that the downstream domain is the first point where one of these is reached:
• at least one reach downstream of the first grade control point • tidal backwater/lentic waterbody
• equal order tributary
• accumulation of 50 percent drainage area for stream systems or 100 percent drainage area for urban conveyance systems (storm drains, hardened channels, etc.).

The upstream limit is defined as:
2 • proceed upstream for 20 channel top widths or to the first grade control point, whichever comes first. Identify hard points that can check headward migration and evidence of active headcutting.

SCCWRP defines the maximum spatial unit, or reach (a reach is circa 20 channel widths), for assigning a susceptibility rating within the domain of analysis to be 200 meters (656 feet). If the domain of analysis is greater than 200 meters,the study area can be subdivided into smaller reaches of less than 200 meters for analysis. Most of the units in the HMP's SCCWRP analysis are metric.

Metric units are used in this report only where given so in the HMP. Otherwise English units are used.

Downstream Domain o Analysis
The downstream domain of analysis location for each point of compliance (POC)was determined by assessing and comparing the four bullet items above. A POC represents the point below which a channel is natural and subject to hydromodification impacts. As discussed in the Introduction, storm runoff from the project will be treated by one of two biofiltration basins and then conveyed below the project by hardened, non-erodible storm drain pipes to natural conveyances. The two outlets into the natural conveyances are labeled POC A and POC B, respectively. A downstream domain of analysis location was selected below each POC as follows.

Per the first bullet item, the first permanent grade controls below POC A and POC B were identified during a site visit. The storm runoff from POC A flows a short distance to the unnamed natural drainage course and then continues west in the unnamed natural drainage course. The runoff reaches the North Santa Fe Avenue culvert approximately 1,000 feet downstream of POC A. The culvert is a non-erodible facility that provides a grade control for the upstream channel bed. i.e., it will prevent erosion of the upstream channel bed. This is the first permanent grade control below POC A.

The storm runoff from POC B discharges directly into the unnamed natural drainage course from the North Santa Fe Avenue culvert outlet. The runoff continues west in the unnamed natural drainage course a distance of 516 feet before reaching a road crossing with a culvert (see Figure 6). This culvert is the first permanent grade control reached below POC B.

The second bullet item criteria are based on reaching a lentic(standing or still water such as ponds, pools, marshes, lakes, lagoons, etc.) or tidal waterbody. The nearest such waterbody below POC A and POC B is the Upper Pond within Guajome Regional Park. The unnamed natural drainage course flows into the Upper Pond over 1.1 miles downstream of North Santa Fe Avenue. This lentic waterbody is further downstream from POC A and POC B than their first permanent grade controls, so the second bullet item will not govern over the first bullet item in establishing the downstream domain of analysis location for either POC.

The third bullet item is met when the natural watercourse below a POC confluences with a stream with an equal order or larger tributary area. The runoff from POC A flows 90 feet within a natural swale before confluencing with the unnamed natural drainage course. Topographic mapping indicates that the unnamed natural drainage course's watershed area at the confluence is much larger than the natural swale's watershed area. Therefore, the third bullet item criteria for POC A 3 is met where the natural swale below POC A confluences with the unnamed natural drainage course. The confluence is closer to POC A than its downstream permanent grade control, so the third bullet item governs over the first in establishing the downstream domain of analysis location for POC A.

POC B is within the unnamed natural drainage course. Google Earth and a site visit reveal that the unnamed natural drainage course does not confluence with a larger stream between POC B and its first permanent grade control located 516 feet below POC B. Therefore, the third bullet item will not govern over the first in establishing the downstream domain of analysis location for POC B.

The fourth bullet item is met when the natural stream below a POC accumulates 50 or 100 percent drainage area for natural or urban drainage systems, respectively. Both streams below each POC are natural systems, so 50 percent applies. The Study Area Exhibit shows that the stream below POC A accumulates minor area(0.35 acres)between POC A and the confluence with the unnamed natural drainage course. The accumulated area is much less than 50 percent of the area tributary to POC A(3.29 acres). Therefore, fourth bullet item will not govern over the third in establishing the downstream domain of analysis location for POC A.

The Study Area Exhibit indicates that the unnamed natural drainage course below POC B accumulates minor area between POC B and its downstream permanent grade control. The accumulated area is much less than 50 percent of the area tributary to POC B. Therefore,the fourth bullet item will not govern over the first in establishing the downstream domain of analysis location for POC A.

Based on the above information, the downstream domain of analysis location is established by separate criteria for POC A and POC B. For POC A, the location is based on the third bullet item.

The natural swale below POC A confluences with the much larger unnamed natural drainage course 90 feet downstream of POC A. This location is closer to POC A than the locations determined by the other bullet item criteria.

For POC B, the downstream domain of analysis location is based on the first bullet item. A permanent grade control occurs where the unnamed natural drainage course enters a roadway culvert below POC B. This is the first downstream domain of analysis point reached from the four bullet criteria. Per the first bullet item, the downstream domain of analysis location should be set one reach (656 feet) below the grade control. Therefore, the downstream domain of analysis location for POC B is 650 feet below the grade control.

Upstream Domain ofAnalysis
The hardened,non-erodible drainage facilities leading to the POC A outlet into the uppermost end of the receiving natural swale. Since the natural swale does not extend upstream of POC A, the upstream domain of analysis location for POC A is at POC A.

The North Santa Fe Avenue culvert extends upstream of POC B. In addition, the project's topographic mapping shows a rock outcropping in the unnamed natural drainage course immediately upstream of the culvert. These culvert and rocks are hard points that check headward 4 migration in the unnamed natural drainage course. Therefore, the upstream domain of analysis location for POC B is at POC B.

Study Reaches within Domain ofAnalysis
After the upstream and downstream domain of analysis locations are established for POC A and POC B, the study reaches associated with each POC are identified (see the Study Area Exhibit in the map pocket). For POC A, the entire domain of analysis extends from the upstream domain of analysis location at POC A to the downstream domain of analysis location at the confluence of the natural swale below POC A with the unnamed natural drainage course. This reach extends over 90 feet and is labeled Reach 1.

For POC B, the entire domain of analysis extends from the upstream domain of analysis location at POC B to the downstream domain of analysis location 656 feet below the permanent grade control created by a roadway culvert. The domain of analysis was analyzed as two study reaches, Reach 2 and Reach 3. Reach 2 extends 516 feet from the upstream domain of analysis location at POC B to the first permanent grade control below POC B. Reach 2 extends from the first permanent grade control to a point 656 feet below the grade control. All three study reaches are within the 656 foot(200 meters) maximum reach length recommended by SCCWRP.

INITIAL DESKTOP ANALYSIS
After the domain of analysis is established, SCCWRP requires an "initial desktop analysis" that involves office work. The initial desktop analysis establishes the watershed area, mean annual precipitation,valley slope, and valley width. These terms are defined in Form 1,which is included in Appendix A. SCCWRP recommends the use of National Elevation Data (NED) to determine the watershed areas, valley slopes, and valley widths. NED data is similar to USGS quadrangle mapping.

The Reach 1 watershed area is based on BHA, Inc's. proposed condition hydrology, which determined that 3.29 acres is tributary to POC A (see Appendix A for their Post-Development Hydrology exhibit). The Study Area Exhibit shows that an additional 0.35 acres is tributary to the natural swale below POC A, so the total Reach 1 watershed area covers 3.64 acres (0.0057 square miles).

The watershed areas associated with Reach 2 and 3 were delineated from the USGS' StreamStats program,which is based on their Digital Elevation Model and a digital representation of the stream network. The StreamStats results are included in Appendix A. The watershed delineations are consistent with current USGS quadrangle mapping. Streamstats shows that the watershed areas tributary to Reach 2 and 3 are 676.46 and 739.62 acres (1.0570 and 1.1557 square miles), respectively.

The mean annual precipitation was obtained from the rain gage closest to the site. This is the Western Regional Climate Center's Vista 2NNE gage (see Appendix A). The average annual rainfall measured at the Vista 2NNE gage for the period of record is 13.09 inches. 5 The valley slope and valley width for Reach 1,2, and 3 were obtained from 1-foot contour interval topographic mapping prepared for the project supplemented with SANGIS' 2014 2-foot contour interval topographic mapping. NED data was not used because it is not very accurate for these parameters. The valley slope is the longitudinal slope of the channel bed along the flow line, so it is determined by dividing the elevation difference within a study reach by the length of the flow line. The valley width is the valley bottom width dictated by breaks in the hillslope. The valley slope and valley width within Reach 1, 2, and 3 along with their watershed areas are included in Table 1.

Reach Tributary Watershed Valley Slope, Valley Width, Area, sq. mi. m/m In
F 1 7 0.0057 1 0.0722 2.44

1.0570 0.0099 9.14

1.1557 0.0136 9.14
Table 1. Summary of Watershed Area, Valley Slope, and Valley Width The above described values were input to a spreadsheet to calculate the simulated peak flow, screening index,and valley width index outlined in Form 1. The input data and results are tabulated in Appendix A. This completes the initial desktop analysis.

FIELD SCREENING
After the initial desktop analysis is complete, a field assessment must be performed. The field assessment is used to establish a natural channel's vertical and lateral susceptibility to erosion.

SCCWRP states that although they are admittedly linked, vertical and lateral susceptibility are assessed separately for several reasons.First,vertical and lateral responses are primarily controlled by different types of resistance, which, when assessed separately, may improve ease of use and lead to increased repeatability compared to an integrated, cross-dimensional assessment. Second, the mechanistic differences between vertical and lateral responses point to different modeling tools and potentially different management strategies. Having separate screening ratings may better direct users and managers to the most appropriate tools for subsequent analyses.

The field screening tool uses combinations of decision trees and checklists. Decision trees are typically used when a question can be answered fairly definitively and/or quantitatively (e.g., d50 < 16 mm). Checklists are used where answers are relatively qualitative (e.g., the condition of a grade control). Low,medium,high, and very high ratings are applied separately to the vertical and lateral analyses. When the vertical and lateral analyses return divergent values, the most conservative value shall be selected as the flow threshold for the hydromodification analyses.

Vertical Stability
The purpose of the vertical stability decision tree (Figure 6-4 in the County of San Diego HMP) is to assess the state of the channel bed with a particular focus on the risk of incision (i.e., down 6 cutting). The decision tree is included in Figure 10. The first step is to assess the channel bed resistance. There are three categories defined as follows:

1. Labile Bed—sand-dominated bed, little resistant substrate.

2. Transitional/Intermediate Bed — bed typically characterized by gravel/small cobble, Intermediate level of resistance of the substrate and uncertain potential for armoring.

3. Threshold Bed(Coarse/Armored Bed)—armored with large cobbles or larger bed material or highly-resistant bed substrate (i.e., bedrock).

Based on the photographs and site investigation,the bed material and resistance is generally within the transitional/intermediate bed category. There was no evidence of a threshold bed condition.

However, some bed areas contained smaller grain sizes typically found in a labile bed.

In addition to the material size and compaction, there are several factors that establish the erodibility of a channel such as the flow rate(i.e.,size of the tributary area),grade controls,channel slope, vegetative cover, channel planform, etc. The Introduction of the SCCWRP Hydromodification Screening Tools: Field Manual identifies several of these factors. When multiple factors influence erodibility, it is appropriate to perform the more detailed SCCWRP analysis, which is to analyze a channel according to SCCWRP's transitional/intermediate bed procedure. This requires the most rigorous steps and will generate the appropriate results given the range of factors that define erodibility. The transitional/intermediate bed procedure takes into account that bed material may fall within the labile category (the bed material size is used in SCCWRP's Form 3 Figure 4), but other factors may trend towards a less erodible condition. Dr.

Eric Stein from SCCWRP, who co-authored the Hydromodification Screening Tools: Field Manual in the Final Hydromodification Management Plan (HMP), indicated that it would be appropriate to analyze channels with multiple factors that impact erodibility using the transitional/intermediate bed procedure. Consequently, this procedure was used to produce more accurate results.

Transitional/intermediate beds cover a wide susceptibility/potential response range and need to be assessed in greater detail to develop a weight of evidence for the appropriate screening rating. The three primary risk factors used to assess vertical susceptibility for channels with transitional/intermediate bed materials are:

1. Armoring potential—three states (Checklist 1)

2. Grade control—three states (Checklist 2)

3. Proximity to regionally-calibrated incision/braiding threshold (Mobility Index Threshold —Probability Diagram)
These three risk factors are assessed using checklists and a diagram (see Appendix B), and the results of each are combined to provide a final vertical susceptibility rating for the intermediate/transitional bed-material group. Each checklist and diagram contains a Category A, 7 B, or C rating. Category A is the most resistant to vertical changes while Category C is the most susceptible.

Checklist 1 determines armoring potential of the channel bed. The channel bed along each of the three study reaches is within Category B, which represents intermediate bed material of unknown resistance or unknown armoring potential due to a surface veneer such as vegetation. The soil was probed and penetration was relatively difficult through the underlying layer. The dense, mature vegetative growth along the channel of Reach 1,2, and 3 serve to armor the channel bed and resist vertical erosion.

Checklist 2 determines grade control characteristics of the channel bed. This is established by the spacing of the grade controls along the channel. Category B on Checklist 2 is based on a spacing of 2/Sv or 4/5,, where Sv is the channel slope. The Sv value of Reach 1, 2, and 3 are included in Form I results in Appendix A and summarized in Table 2. Table 2 also summarizes the 2/Sv or 4/Sv of each reach along with the length. Reach 1 and Reach 2 are both shorter than their 2/Sv values, so are in Category A on Checklist 2. On the other hand, Reach 3 is between its 2/Sv and 4/Sv, so is in Category B.

Reach FS,, ft/ft I 2/Sv,feet I 4/Sv,feet I Length, feet Category

0.0722 1 91 1 182 1 90

0.0099 1 664 F 1,328 1 516

0.0136 1 484 F 967 1 656
Table 2. Checklist 2 Summary
The Screening Index Threshold is a probability diagram that depicts the risk of incising or braiding based on the potential stream power of the valley relative to the median particle diameter. The threshold is based on regional data from Dr. Howard Chang of Chang Consultants and others. The probability diagram is based on dso as well as the screening index (INDEX) value determined in the initial desktop analysis (see Appendix A). The Form 1 results in Appendix A determined an INDEX of 0.0147 and 0.0196 for Reach I and Reach 2, respectively. SCCWRP specifies use of a US SAH-97 half-phi template gravelometer to determine dso in a natural channel. This gravelometer allows a minimum dso measurement of 2 millimeters.The Screening Index Threshold diagram shows that the probability of incising or braiding is less than 50 percent for a dso of 2 millimeters if the INDEX value is 0.022 or less. Since the Reach 1 and Reach 2 Screening Index values are both less than the 50 percent INDEX value, Reach 1 and Reach 2 are both within Category A.

For Reach 3, dso had to be determined to assess the Screening Index Threshold. dso can be derived from a pebble count in which a minimum of 100 particles are obtained along transects at the site.

SCCRWP states that if fines less than 1/2-inch thick are at a sample point,it is appropriate to sample the coarser buried substrate. The dso value is the particle size in which 50 percent of the particles are smaller and 50 percent are larger. The pebble count results for Reach 3 are included in Appendix B. The results show a dso of 8 millimeters. Plotting the dso and screening index value on 8 the Mobility Index Threshold diagram shows Reach 3 has a less than 50 percent probability of incising or braiding,which falls within Category A.

The overall vertical rating is determined from the Checklist 1, Checklist 2, and Mobility Index Threshold results. The scoring is based on the following values:

Category A= 3, Category B = 6, Category C= 9
The vertical rating score is based on these values and the equation:

Vertical Rating= [(armoring X grade control)112 X screening index scoref2 Table 3 summarizes the Checklist 1, 2, and 3 values for each reach as well as their vertical rating.

The results show the vertical rating for all three study reaches is less than 4.5, so these reaches have a low threshold for vertical susceptibility.

Reach Checklist 1 Checklist 2 Checklist 3 Vertical (armoring) (grade control) (screening index) Rating 6 3 F- 3 3.6
2 6 3 3 3.6
6 6 3 4.2
Table 3. Overall Vertical Rating
Lateral Stability
The purpose of the lateral decision tree (Figure 6-5 from County of San Diego HMP included in Figure 11)is to assess the state of the channel banks with a focus on the risk of widening. Channels can widen from either bank failure or through fluvial processes such as chute cutoffs, avulsions, and braiding. Widening through fluvial avulsions/active braiding is a relatively straightforward observation. If braiding is not already occurring, the next logical step is to assess the condition of the banks. Banks fail through a variety of mechanisms; however, one of the most important distinctions is whether they fail in mass (as many particles) or by fluvial detachment of individual particles. Although much research is dedicated to the combined effects of weakening, fluvial erosion, and mass failure, SCCWRP found it valuable to segregate bank types based on the inference of the dominant failure mechanism(as the management approach may vary based on the dominant failure mechanism). A decision tree (Form 4 in Appendix B) is used in conducting the lateral susceptibility assessment. Definitions and photographic examples are also provided below for terms used in the lateral susceptibility assessment.

The first step in the decision tree is to determine if lateral adjustments are occurring. The adjustments can take the form of extensive mass wasting (greater than 50 percent of the banks are exhibiting planar, slab, or rotational failures and/or scalloping, undermining, and/or tension cracks). The adjustments can also involve extensive fluvial erosion(significant and frequent bank cuts on over 50 percent of the banks). Neither mass wasting nor extensive fluvial erosion was evident within either of the three reaches during a field investigation. As seen in the figures and 9 topographic mapping, the channel banks are mostly gentle and heavily vegetated confirming that mass wasting and extensive fluvial erosion has not occurred.

The next step in the Form 4 decision tree is to assess the consolidation of the bank material. The banks in Reach 1, 2, and 3 were moderate to well-consolidated. This determination was made because the ground surface was difficult to penetrate with a probe. The banks were densely vegetated and/or relatively level and stable as seen in the figures. In addition, the banks showed little evidence of crumbling and were composed of relatively well-packed particles.

Form 6 (see Appendix B) is used to assess the probability of mass wasting. Form 6 identifies a 10, 50, and 90 percent probability based on the bank angle and bank height. From the topographic mapping and site investigation, the average bank angles in all three reaches are 2:1 (26.6 degrees) or flatter.Form 6 shows that the probably of mass wasting and bank failure has less than 10 percent risk for a 26.6 degree bank angle or less regardless of the bank height.

The final two steps in the Form 4 decision tree are based on the braiding risk determined from the vertical rating as well as the Valley Width Index (VWI) calculated in Appendix A. If the vertical rating is high,the braiding risk is considered to be greater than 50 percent. Excessive braiding can lead to lateral bank failure. For Reach 1, 2, and 3 the vertical rating is low, so the braiding risk is less than 50 percent.Furthermore,a VWI greater than 2 represents channels unconfined by bedrock or hillslope and, hence, subject to lateral migration. The VWI calculations in the spreadsheet in Appendix A show that VWI for Reach 1, 2, and 3 are 1.40, 0.72, and 0.70,respectively,which are all less than 2.

From the above steps, the lateral susceptibility rating is low for Reach 1, 2, and 3 (colored circles are included on the Form 4:Lateral Susceptibility Field Sheet decision tree in Appendix B showing the decision path).

CONCLUSION
The SCCWRP channel screening tools were used to assess the downstream channel susceptibility for the Camino Largo single-family residential project being designed by BHA, Inc. Storm runoff from the project will be collected by proposed on-site drainage systems, treated by one of two on- site BMPs, and conveyed off-site by storm drain pipes. A channel assessment was performed for the natural streams below each POC based on office analyses and field work. The results indicate a low threshold for vertical and lateral susceptibilities for Reach 1, 2, and 3.

The HMP requires that these results be compared with the critical stress calculator results outlined in the County of San Diego HMP. The critical stress results are included in Appendix B for the study reach using the spreadsheet provided by the County. The channel dimensions were estimated from topographic mapping and Google Earth. Based on these values, the critical stress results returned a low threshold consistent with the SCCWRP channel screening results. Therefore, the SCCWRP analyses and critical stress calculator demonstrate that a low overall threshold is applicable to the project (i.e., 0.5Q2).
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&sdmu F 0 HIGH 6rabi MED HFGH 6rar[Sf'g Bn 6ry nsk c[-04► hf a 2 Yr%I r 2 r�k� AX VWI 5 2 VVll r 2 ripr t r frak i 9J16 �n hx
F lg.rrro&a
or&m
Dmilon
klldlrx
Figure6-5. La[era!ChanneiSusceptlifity
Figure 11. SCCWRP Lateral Channel Susceptibility Matrix 17 APPENDIX A

SCCWRP INITIAL DESKTOP ANALYSIS

FORM 1 : INITIAL DESKTOP ANALYSIS
Complete all shaded sections.

IF required at multiple locations, circle one of the following site types:

Applicant Site/Upstream Extent/Downstream Extent
Location: Latitude: Longitude:

Description (river name, crossing streets, etc.):

GIS Parameters: The International System of Units(SI)is used throughout the assessment as the field standard and for consistency with the broader scientific community. However, as the singular exception, US Customary units are used for contributing drainage area (A)and mean annual precipitation (P)to apply regional flow equations after the USGS. See SCCWRP Technical Report 607 for example measurements and"Screening Tool Data Entry.xls"for automated calculations.

Form 1 Table 1. Initial desktop analysis in GIS.

Symbol Variable Description and Source Value A Area Contributing drainage area to screening location via published (mi) Hydrologic Unit Codes(HUCs)and/or<_30 m National Elevation Data F (NED), USGS seamless server
m a.
o P Mean annual Area-weighted annual precipitation via USGS delineated polygons using w precipitation records from 1900 to 1960 (which was more significant in hydrologic (in) models than polygons delineated from shorter record lengths) S Valley slope Valley slope at site via NED, measured over a relatively homogenous (m/m) valley segment as dictated by hillslope configuration,tributary a confluences, etc., over a distance of up to—500 m or 10%of the main- channel length from site to drainage divide
o
a_ W Valley width Valley bottom width at site between natural valley walls as dictated by a? (m) clear breaks in hillslope on NED raster, irrespective of potential i) armoring from floodplain encroachment, levees, etc. (imprecise measurements have negligible effect on rating in wide valleys where VWI is»2, as defined in lateral decision tree)
Form 1 Tabl a 2. Simplif ied peak flo w, screening index, and valley width index. Values for this table should be calculated in the sequence shown in this table, using values from Form 1 Table 1.

Symbol Dependent Variable Equation Required Units Value Q10cfs 10-yr peak flow (ft3/s) Qlocfs= 18.2*A 0.87*P 0.77 A(mi) P (in)
Q10 10-yr peak flow (m3/S) Q10=0.0283*Qlocfs Qlocfs(ft3/s) INDEX 10-yr screening index(m1.5/s.5) INDEX=Sv*Q10 0.5 Q 1 (M3/o(m S) Wref Reference width (m) Wref=6.99*Q10 0.438 Q10(m3/s) VWI Valley width index(m/m) VWI =W/Wref W,(m)
Wref(m)
(Sheet 1 of 1)
B - 3

SCCWRP FORM 1 ANALYSES
Area Mean Annual Precip. Valley Slope Valley Width 10-Year Flow 10-Year Flow Reach A, sq. mi. P, inches Sv, m/m Wv, m Q10cfs, cfs Q10,cros 1 0.0057 13.09 0.0722 2.44 1.5 0.04 2 1.0570 13.09 0.0099 9.14 138.4 3.92 3 1.1557 13.09 0.0136 9.14 149.5 4.23 10-Year Screening Index Reference Width Valley Width Index Reach INDEX Wref, m VWI, m/m
1 0.015 1.74 1.40
2 0.020 12.71 0.72
3 0.028 13.15 0.70

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StreamStats Report
Region ID: CA
Workspace ID: CA20210804003918730000
Clicked Point (Latitude, Longitude): 33.23230, -117.25114 Time: 2021-08-0317:39:35 -0700
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Basin Characteristic
Parameter Code Parameter Description Value Unit DRN AREA Area that drains to a point on a stream 1 .0570 square miles General Disclaimers

StreamStats Report
Region ID: CA
Workspace ID: CA20210804003221740000
Clicked Point (Latitude, Longitude): 33.23239, -117.25345 Time: 2021-08-03 17:32:38 -0700
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Basin Characteristics
Parameter Code Parameter Description Value Unit DRNAREA Area that drains to a point on a stream 1 .1557 square miles General Disclaimers

ON
Guajome .. '
Park
Hidden-'
kleadows
t
Vista y. JC ` t
' r * ► M
7 �+ F
,F.
wo
_A;
C

VISTA 2 NNE, CALIFORNIA (049378)
Period of Record Monthly Climate Summary
Period of Record : 08/01/1957 to 05/12/2016
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Average Max. Temperature (F) 67.4 67.8 68.2 70.8 72.9 76.3 81.3 83.0 82.2 77.9 72.3 67.4 74.0 Average Min. Temperature (F) 44.0 45.0 46.3 48.5 53.5 56.6 60.3 61.6 60.0 55.0 48.3 44.0 51.9 Average Total Precipitation 2.76 2.55 2.24 1.05 0.22 0.11 0.06 0.07 0.25 0.54 1.40 1.83 13.09 (in.)
Average Total SnowFall (in.) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 Average Snow Depth (in.) 0 0 0 0 0 0 0 0 0 0 0 0 0 Percent of possible observations for period of record.

Max. Temp.: 86.6% Min. Temp.: 87% Precipitation: 87.6% Snowfall: 87.7% Snow Depth: 87.3% Check Station Metadata or Metadata graphics for more detail about data completeness.

Western Regional Climate Center, iLrcc@&ri.edu

APPENDIX B

SCCWRP FIELD SCREENING DATA

Form 3 Support Materials
Form 3 Checklists 1 and 2, along with information recording in Form 3 Table 1, are intended to support the decisions pathways illustrated in Form 3 Overall Vertical Rating for Intermediate/Transitional Bed.

Form 3 Checklist 1: Armoring Potential
❑ A A mix of coarse gravels and cobbles that are tightly packed with 25% surface material of diameter<2 mm

ARMORING POTE
most resistant least resistant
at.

PP +i
Form 3 Figure 2. Armoring potential photographic supplement for assessing intermediate beds (16 < d50 < 128 mm) to be used in conjunction with Form 3 Checklist 1. (Sheet 2 of 4)
REACH 1, 29 AND 3 RESULTS
B - 7

Form 3 Checklist 2: Grade Control
❑ A Grade control is present with spacing 30 cm), no active mass wasting (analyst cannot say grade control sufficient if mass- wasting checklist indicates presence of bank failure), no exposed bridge pilings, no culverts/structures undermined
• Hard points in serviceable condition at decadal time scale, e.g., no apparent undermining, flanking, failing grout
• If geologic grade control, rock should be resistant igneous and/or metamorphic; For sedimentary/hardpan to be classified as `grade control', it should be of demonstrable strength as indicated by field testing such as hammer test/borings and/or inspected by appropriate stakeholder ❑ B Intermediate to A and C — artificial or geologic grade control present but spaced 2/Sv m to 4/Sv m or potential evidence of failure or hardpan of uncertain resistance
❑ C Grade control absent, spaced >100 m or >4/Sv m, or clear evidence of ineffectiveness
C)Ineffective Grade
. .-r. .C.r / •9F.

AP
36,
some undermining at road crossing 4M substantial underminin9� Form 3 Figure 3. Grade-control (condition) photographic supplement for assessing intermediate beds (16 < d5o < 128 mm)to be used in conjunction with Form 3 Checklist 2. (Sheet 3 of 4)
B - 8

Regionally-Calibrated Screening Index Threshold for Incising/Braiding For transitional bed channels (d5o between 16 and 128 mm) or labile beds (channel not incised past critical bank height), use Form 3 Figure 3 to determine Screening Index Score and complete Form 3 Table 1.
1 '
0 +X +
0 1 + 7 + 128 0.145
0 96 0.125
o 0.01 LO E 80 0.114
UJ m
� 64 0.101
U Al

0.001 y 48 0.087

0.1 1 d5n (mm) 10 100 0 32 0.070 16 0.049
• Stable - Braided -F Incising 8 0.031 10%risk 50%risk 90%risk 6 E
� E 4 0.026
- • f • - • • - `L) `9
2 0.022
V
Field-derived: r • 00 • -• • - • o 1 0.018

0.5 0.015
Form 3 Figure 4. Probability of incising/braiding based on logistic regression of Screening Index and d5o to be used in conjunction with Form 3 Table 1.

Form 3 Table 1. Values for Screening Index Threshold (probability of incising/braiding)to be used in conjunction with Form 3 Figure 4 (above)to complete Form 3 Overall Vertical Rating for Intermediate/Transitional Bed (below).. Screening Index Score: A= 50% probability of incising/braiding for current Q10, valley slope, and d50- d50 (mm) SV*Q100.5 (m1.5/50.5) o Sv*Q100.5 (m1.5/s0.5) Screening Index Score From Form 2 From Form 1 50/ risk of incising/braiding (A, B, C) from table in Form 3 Figure 3 above
Overall Vertical Rating for Intermediate/Transitional Bed Calculate the overall Vertical Rating for Transitional Bed channels using the formula below.

Numeric values for responses to Form 3 Checklists and Table 1 as follows: A= 3, B = 6, C = 9.

Vertical Rating armoring„grade controi x screening index score Vertical Susceptibility based on Vertical Rating: 7 = HIGH. (Sheet 4 of 4)
B - 9

PEBBLE COUNT
Reach 3
# Diameter, mm
1 2
2 2
3 2
4 2
5 2
6 2
7 2
8 2
9 2.8
10 2.8
11 2.8
12 2.8
13 2.8
14 2.8
15 2.8
16 2.8
17 2.8
18 2.8
19 2.8
20 2.8
21 4
22 4
23 4
24 4
25 4
26 4
27 4
28 4
29 4
30 4
31 4
32 4
33 4
34 4
35 4
36 4
37 4
38 4
39 4
40 4
41 5.6
42 5.6
43 5.6

Reach 3
# Diameter, mm
44 5.6
45 5.6
46 5.6
47 5.6
48 5.6
49 8
50 8
51 8
52 8
53 8
54 8
55 8
56 8
57 8
58 8
59 8
60 8
61 8
62 8
63 8
64 8
65 8
66 8
67 8
68 8
69 8
70 8
71 8
72 8
73 8
74 8
75 8
76 8
77 11
78 11
79 11
80 11
81 11
82 11
83 11
84 11
85 11
86 11
87 11
88 11

Reach 3
# Diameter, mm
89 11
90 11
91 11
92 11
93 11
94 16
95 16
96 16
97 16
98 16
99 16
100 16

O - LATERAL
Circle appropriate nodes/pathway for proposed site
OR use sequence of questions provided in Form 5.

LATERALLY AaJUSTABLE?
no yes
LOW
•Fullyarmared� Are lateral adjustr�ent5 occurring? bedrock bank nQ yes
stabilization in good
condition
•No evidence of IJone,ar fluvial only limited to bends and constrictions Mass wasting or extensive fluvial chute formation! erosion or chute cutoff formation avulsions
•Fully confined,directly All bank strata consolidated including toe?

HIGH VERY HIGH
ci ected to hillslape, yes I1Q VUVI 2
iy or
_ Probabilistic - - PDOflyl Or 11I1CDI15alldaied Bank he
10°�logistic 1096 logistic risk Coarse! Fine Fine risk for angle risk for angle forangle,AIJQ resistant toe, unconsolidated unconsolidated AND VNII 5 2 VWI�2 d�64 mm ANQ VWI 5 2 ANQ VWI �2 (Sheet I
Vertical Vertical MED HIGH HIGH VERY Vertical Vertical MEN HIGH HIGH VERY rating rating Vert. Vertical Vertical HIGH rating rating Vert_ Vertical Vertical HIGH �high �high _high _high �high �high �high Vertical >_high �high
LOW MEN AREA HIGH LOW MEG MEN HIGH VWI 5 2 VWI>2 VWI 5 2 VWI>2 V1M 5 2 VWI}2 VWI s 2 VWI>2 of
1 3 RESULTS
10 FORM 6: PROBABILITY OF MASS WASTING BANK FAILURE
If mass wasting is not currently extensive and the banks are moderately- to well-consolidated, measure bank height and angle at several locations (i.e., at least three locations that capture the range of conditions present in the study reach)to estimate representative values for the reach. Use Form 6 Figure 1 below to determine if risk of bank failure is >10% and complete Form 6 Table 1. Support your results with photographs that include a protractor/rod/tape/person for scale.

Bank Angle Bank Height Corresponding Bank Height for Bank Failure Risk (degrees) (m) 10% Risk of Mass Wasting (m) ( 10% Risk) Left Bank
Right Bank
(I O��Risk of t
Mass Wasting)
30 7.6
O Stable - 10%Risk 50%Risk 90%Risk X Unstable 35 4.7 4 40 3,7
l 3C
45 2.1
Q
10 X X so 1.5
3 X 55 1.1
} X x X 60 0.85
r �
2 0 • X 65 0.66
000 XX X 70 0.52
0 c0 � O X ` X X 80 0,34
G 00 0 (9
— ti 90 0.24
0q) 00 Qd p 0 —
0 30 40 50 60 70 80 90
Bank Angle(degrees) �
Form 6 Figure 1. Probability Mass Wasting diagram, Bank Angle:Height/% Risk table, and Band Height:Angle schematic.
(Sheet 1 of 1)
B - 12

Critical Flow Calculator Reach 1
enter all values in green cells
and drop down boxes
a
Inputs
a) Receiving channel width at top of 40.0
bank (ft)-see figure on right c
b) Channel width at bed (ft) 8.0
c) Bank height at top of bank (ft) 1.0
b
Channel gradient(ft/ft) 0.0722
Receiving channel roughness Same as above,but more stones and weeds n=0.035 Channel materials (use weakest of unconsolidated sandy loam 0.035 lb/sq ft bed or banks). If materials are varied alluvial silt(non coloidal)0.045 lb/sq ft use weakest material covering more medium gravel 0.12 lb/sq ft than 20% of channel. alluvial silt/clay 0.26 lb/sq ft

2.5 inch cobble 1.1 lb/sq ft
enter own d50(variable)
ve etation bed and banks 0.6 lb/sq ft
Select method of calculating Q2 Input own Q2
[calculate Q2 using USGS regression
Receiving water watershed annual 13.09 Receiving water watershed 0.0057 precip (inches) area at PoC (sq mi)
Project watershed annual 13.09 Project watershed area 0.0057 precipitation (inches) draining to PoC (sq mi)
Outputs - Flow control range
Point of Compliance low
Receiving water Q2 0.2 flow rate (cfs) 0.1 Project site Q2 0.2 Low flow class 0.502
Channel vulnerability

Critical Flow Calculator Reach 2
enter all values in green cells
and drop down boxes
a
Inputs
a) Receiving channel width at top of 38.0
bank (ft)-see figure on right c
b) Channel width at bed (ft) 30.0
c) Bank height at top of bank (ft) 2.0
b
Channel gradient(ft/ft) 0.0099
Receiving channel roughness Same as above,but more stones and weeds n=0.035 Channel materials (use weakest of unconsolidated sandy loam 0.035 lb/sq ft bed or banks). If materials are varied alluvial silt(non coloidal)0.045 lb/sq ft use weakest material covering more medium gravel 0.12 lb/sq ft than 20% of channel. alluvial silt/clay 0.26 lb/sq ft

2.5 inch cobble 1.1 lb/sq ft
enter own d50(variable)
ve etation bed and banks 0.6 lb/sq ft
Select method of calculating Q2 Input own Q2
[calculate Q2 using USGS regression
Receiving water watershed annual 13.09 Receiving water watershed 1.0570 precip (inches) area at PoC (sq mi)
Project watershed annual 13.09 Project watershed area 1.0570 precipitation (inches) draining to PoC (sq mi)
Outputs - Flow control range
Point of Compliance low
Receiving water Q2 9.4 flow rate (cfs) 4.7 Project site Q2 9.4 Low flow class 0.5Q2
Channel vulnerability •

Critical Flow Calculator Reach 3
enter all values in green cells
and drop down boxes
a
Inputs
a) Receiving channel width at top of 38.0
bank (ft)-see figure on right c
b) Channel width at bed (ft) 30.0
c) Bank height at top of bank (ft) 2.0
b
Channel gradient(ft/ft) 0.0136
Receiving channel roughness Same as above,but more stones and weeds n=0.035 Channel materials (use weakest of unconsolidated sandy loam 0.035 lb/sq ft bed or banks). If materials are varied alluvial silt(non coloidal)0.045 lb/sq ft use weakest material covering more medium gravel 0.12 lb/sq ft than 20% of channel. alluvial silt/clay 0.26 lb/sq ft

2.5 inch cobble 1.1 lb/sq ft
enter own d50(variable)
ve etation bed and banks 0.6 lb/sq ft
Select method of calculating Q2 Input own Q2
[calculate Q2 using USGS regression
Receiving water watershed annual 13.09 Receiving water watershed 1.1557 precip (inches) area at PoC (sq mi)
Project watershed annual 13.09 Project watershed area 1.1557 precipitation (inches) draining to PoC (sq mi)
Outputs - Flow control range
Point of Compliance low
Receiving water Q2 10.0 flow rate (cfs) 5.0 Project site Q2 10.0 Low flow class 0.5Q2
Channel vulnerability •

S
A-
PE S \;i PE 314.5
• ./l PE 347
• _
, ��' /I� �_�i�i / - \• E 341.1 P-'t '�• PE 314.5 � PE�30. I
., 1 � / �ii�i�� / \l\\ PE 3Mf. - ^�•L� A` PE 308.0 900 9P
(FROM BHA, INC. HYDROLOGY) 4141
AN re
GRAPHIC SCALE 1 �% POC AAT STORM DRAIN OUTFALL PE 336.,

FROM PROJECT UPSTREAM DOMAIN
\\
100 0 50 100 200 1 OF ANALYSIS 'LOCATION FOR `REACH 1
ALONG SW AL
ALE U.3�NATURAL S W y=`
E 319.0 \ p � E 328.5 PE 331.1 C _ - AC
/ \\ \ �E 3_3.5 \\ PE 321.1 1 t - :/, 1 INCH = 100 FEET
r/l E3190 1 E323.5 PE326.1EACH 1
•• „ = / PE 328.5 -
/ PE 3
t
PE 317. PE 323.5 1 / E 318.5 PE $21.1 /, ��• \, N MR
E 312.7 318.5 _� uOWNSTREAM DOMAIN OF ANALYSISP PE /.. LOCATION FOR REACH 1 AT CONFLUENCE

OF NATURAL SWALE WITH UNNAMED
\ PE 307.7 PE 313.5 I -,
:NATURAL DRAINAGE COURSE

PROPOSED STORM DRAIN
FROM PROJECT �; , r, i

POC B AT NORTH SANTA FIE AVENUE
CULVERT OUTFACE - UPSTREAM � :.,� ,1r .., � DOMAIN OF ANALYSIS LOCATION FOR � • 11110 REACH 2 ALONG UNNAMED NATURAL , _EXISTING NORTH SANTA DRAINAGE COURSE? \ 1�\ ` �„ ''' AVENUE ARCH CULVERT L� 2�
DOWNSTREAM DOMAIN OF ANALYSIS LEGEND:

LOCATION FOR REACH 3 ALONG-
: UNNAMED NATURAL DRAINA, E
DRAINAGE BASIN BOUNDARY TRIBUTARY TO REACH 1 RE 3.29 AC DRAINAGE BASIN AREA (�65N�3 DOWNSTREAM DOMAIN OF ANALYSIS LOCATION 6) , FOR REACH 2 AND UPSTREAM DOMAIN OF PROPOSED PROJECT ANALYSIS LOCATION FOR REACH 3 AT
ROADWAY CULVERT CROSSING.

PROPOSED DRAINAGE FACILITY
A17 EXISTING DRAINAGE FACILITY .0 • • STUDY REACH

CAMINO LARGO

STUDY AREA EXHIBIT

ATTACHMENT 2D- FLOW CONTROL FACILITY DESIGN

Page 54 of 73 ends

HYDROMODIFICATION MANAGEMENT PLAN (HMP)
SWMM Modeling for Hydromodification Compliance of:

CAMINO LARGO
2123 N. Santa Fe Ave
Vista, CA 92084
APN: 159-240-07
Prepared For:

Kyun Tae Kim
Frank Sohaei, Trustee of the Falor Family Trust
2359 Pio Pico Drive
Carlsbad, CA 92008
(760) 420-1267
December 6, 2021
Prepared By:

Q�OVEssroy.

Bruce Rice, R.C.E. 60676 Expires 12/31/22 DateUi 60676 � C10-
b1 A, Inc OFcp'oF ¢
land planning, civil engineering, surveying
5115 Avenida Encinas, Suite L
Carlsbad, CA 92008-4387
(760) 931-8700
W.O. 944-1154-401
1 HYDROMODIFICATION MANAGEMENT PLAN (HMP)
SWMM Modeling for Hydromodification Compliance of:

Camino Largo Project, City of Vista, CA

INTRODUCTION
This document summarizes the approach used to model the proposed Camino Largo project site in the City of Vista using the Environmental Protection Agency (EPA) Storm Water Management Model 5.1 (SWMM). SWMM simulations were prepared for the pre and post-development conditions at the site in order to determine if the proposed LID biofiltration facilities have sufficient volume to meet the current Hydromodification Management Plan (HMP) requirements from the San Diego Regional Water Quality Control Board (SDRWQCB), as established in the Model BMP Design Manual San Diego Region (BMPDM) for the County of San Diego Copermittees, which includes the City of Vista.

SWMM MODEL DEVELOPMENT
The Camino Largo Project proposes the development of a forty six (46) lot residential subdivision, with individual level building pads, driveways and landscaping areas on 8.86 gross acres. The project also proposes the minor widening and improvement of the Camino Largo private drive, which will include paving, sidewalks with curb and gutter. Approximately 53%of the property will be impervious. Biofiltration basins are proposed for the two main drainage basins for POC-1 and POC-2. Proposed grading has been minimized as much as possible to maintain existing slope and drainage patterns.

POC-1
There is one (1) biofiltration basin proposed, which will outlet into an existing storm drain along-side North Santa Fe Avenue south of Camino Largo and discharge from the site at POC-1.

POC-2
There is one (1) proposed biofiltration basin, which outlets via a storm drain into a natural swale at POC-2.

Additional offsite areas along the easterly boundary and towards the northeast is diverted around the development via drainage channels and rip rap, to discharge as historically over Camino Largo and sheet flows into a natural swale.

Two(2)SWMM simulations were prepared for each POC in the study:the first for pre-development and the second for the post-developed conditions.

The development drainage patterns reflected on the DMA Exhibit will remain approximately the same acreage draining to the southwest corner (POC-1), while acreage is increased in the post-development condition in the southeast corner (POC-2). Both POCs include impervious contributing area and require SWMM continuous simulation analysis to prove compliance with HMP requirements.

TABLE 1—CONTRIBUTING AREA—PRE-DEVELOPMENT VS. POST-DEVELOPMENT POC ID Pre-Dev Area (Ac) Post-Dev Area (Ac) Difference POC 1 4.952 4.847 -0.104
POC 2 4.153 5.055 0.902
The SWMM was used since we have found it to be more comparable to San Diego area watersheds than the alternative San Diego Hydrology Model (SDHM) and also because it is a non-proprietary model approved by the HMP document. For both SWMM simulations, flow duration curves were prepared to determine if the proposed HMP facilities are sufficient to meet the current HMP requirements.

The inputs required to develop SWMM simulations include rainfall, watershed characteristics, and BMP configuration. The Oceanside Gage from the Project Clean Water website was used for this study, since it is the most representative of the project site precipitation due to elevation and proximity to the project site.

Per the California Irrigation Management Information System "Reference Evaporation Zones" (CIMIS ETo Zone Map),the project site is located within the Zone 4 Evapotranspiration Area. Thus evapotranspiration values for the site were modeled using Zone 4 monthly values from Table G.1-1 from the City of Vista BMP Design Manual.

The on-site soil classification is Type C and Type D from USDA Web Soil Survey. Type D soils will be used in POC-1 and POC-2 because it is the main soils type in each DMA(see References).

Onsite soil areas have been assumed to be non-compacted in the existing condition to represent the current condition of the site and fully compacted in the post development conditions. Other SWMM inputs for subareas are discussed in the appendices to this document, where the selection of the parameters is explained in detail.

HMP MODELING
POC-1
DMA 1 will drain into a biofiltration basin which will outlet into an existing storm drain along-side North Santa Fe Avenue south of Camino Largo and discharge from the site at POC-1. Once flows are routed via the proposed BMP, the flow is then conveyed via storm drain to the aforementioned POC. Tables 2.1 and 2.2 summarize data for the POC-1 DMAs.

TABLE 2.1—SUMMARY OF EXISTING CONDITIONS FOR POC-1
DMA Tributary Area,A(Ac) Impervious
Percentage, Ip
DMA 1 4.952 0.00%
TOTAL 4.952 1 -

TABLE 2.2—SUMMARY OF DEVELOPED CONDITIONS FOR POC-1
DMA Tributary Area,A(Ac) Impervious
Percentage, Ip
DMA 1 4.706 58.42%
BMP 1 0.141 0.00%
TOTAL 4.847 1 -
(1) BMP Areas are separate from the overall DMA to ensure areas are not double counted.

POC-2
There is one (1) proposed biofiltration basin, which outlets via a storm drain into a natural swale at POC-2.

Additional offsite areas along the easterly boundary and towards the northeast is diverted around the development via drainage channels and rip rap, to discharge as historically over Camino Largo and sheet flows into a natural Swale.

Once flows are routed via the proposed BMPs,flows are then conveyed via storm drain to the aforementioned POC.

Tables 2.3 and 2.4 summarize data for the POC-2 DMAs.

TABLE 2.3—SUMMARY OF EXISTING CONDITIONS FOR POC-2
DMA Tributary Area,A(Ac) Impervious
Percentage, Ip
DMA 2 3.121 0.00%
BYPASS 1 1.031 0.00%
TOTAL 4.153 1 -
TABLE 2.4—SUMMARY OF DEVELOPED CONDITIONS FOR POC-2
DMA Tributary Area,A (Ac) Impervious
Percentage, Ip
DMA 2 3.146 57.73%
BMP 2 0.213 0.00%
BYPASS 2 1.696 0.00%
TOTAL 5.055 -
(1) BMP Areas are separate from the overall DMA to ensure areas are not double counted.

Biofiltration basins in 1 and 2 are responsible for handling hydromodification requirements for POC-1 and POC-2.

Basins 1 and Basin 2 will have a ponding depth of 6 inches. BMPs are comprised of an 18-inch layer of amended soil (a highly sandy,organic rich compost with an infiltration capacity of at least 5 in/hr),and a 7-inch reservoir layer of gravel for additional detention, and to accommodate the French drain system. Below the reservoir layer, the basins will include 3 inches of saturated storage. Flows will discharge from the basin via a low-flow orifice outlet within the gravel layer to the receiving storm drain system. A riser structure will be constructed within the BMP with multiple low-flow orifices and an emergency overflow, such that peak flows can be safely discharged to the storm drain system (see dimensions in Table 3 and 4).

General Considerations
The biofiltration basins (BMP 1 and BMP 2) were modeled using the biofiltration LID module within SWMM. The biofiltration module can model the underground gravel storage layer, underdrain with orifice plate, amended soil layer, and a surface storage pond up to the elevation of the invert of the lowest surface discharge opening in the basin riser structure. Ponding above the invert of the lowest surface discharge opening in the basin riser structure is modeled as a detention basin: elevation vs. area, and elevation vs. discharge tables, are needed by SWMM for Modified Puls routing purposes. Detailed outlet structure location and elevations should be shown on the construction plans based on the recommendations of this study.

BMP MODELING FOR HMP PURPOSES
Modeling of dual purpose Water Quality/HMP IMP
HMP-BMP biofiltration basins are proposed for hydromodification conformance and flood control for the project site. Tables 3 and 4 illustrate the dimensions required for HMP compliance according to the SWMM model that was undertaken for the project. Flood control is discussed within the Drainage Report prepared by BHA for this project.

TABLE 3—SUMMARY OF DUAL PURPOSE BMP: Biofiltration with Surface Ponding Dimensions
Biofiltration Tributary BMP Underdrain Total Riser Min.

BMP Area (Ac) Area(l) Orifice, D(�) Gravel Invert Total ft2 in De th(3) Elev, Surface
BMP 1 4.706 6,147 4.00 7 18 12
BMP 2 3.121 1 9,279 3.00 7 18 12
Notes: (1):Area of amended soil =area of gravel =area of BMP. (2):Diameter of the orifice in gravel layer with invert at bottom of layer; tied with hydromod min threshold (50%Q2).
(3):Total depth of gravel including 3"of saturated storage located below (4):Depth from bottom of pond to invert of emergency overflow weir.

TABLE 4—SUMMARY HMP RISER SURFACE DISCHARGE STRUCTURES
Lower Slot Dimensions Upper Slot Dimensions Emergency Weir Biofiltration Outlet (#) -Width x Outlet Invert Invert (#)-Width Riser Weir BMP Elev, HL(Z) (3i (�l (in) (in) Elev, Length Elev, HL(�) x Height Invert Perimeter (in)
Type(1i ' Height(in) Type (3) (5)
BMP 1 Slot 6 (1) -34 x 5 Slot 7 (1) - 10 x 4 18 11.83 BMP 2 Slot 6 (1) -32 x 3 Slot 7 (1)-6 x 2 18 11.83 Notes: (1):Shape of orifice opening in riser structure. (2): Depth from bottom of pond to invert of lower slot or weir. (3): Number of slots and slot dimensions: For example for BMP 1: Two 29-inch wide by 3-inch high slots at 6-inches above bottom of basin and one 10-inch wide by 3-inch high slot at 7-inches above bottom of basin.
(4): Depth from bottom of pont to invert of emergency overflow weir. (5):Overflow length,the internal perimeter of the riser.

FLOW DURATION CURVE COMPARISON
The Flow Duration Curve (FDC) for the site was compared at POC-1 and POC-2 by exporting the hourly runoff time series results from SWMM to a spreadsheet. At both POCs, the FDC was compared between 10% of the existing condition Q2 up to the existing condition Q1o. The Q2 and Q10 were determined using a partial duration statistical analysis of the runoff time series in an Excel spreadsheet using the Weibull plotting position method.

The range between 10% of Q2 and Q10 was divided into 100 equal time intervals; the number of hours that each flow rate was exceeded was counted from the hourly series. Additionally, the intermediate peaks with a return period "I" were obtained (Qi with i=3 to 9). For the purpose of the plot, the values were presented as percentage of time exceeded for each flow rate. FDC comparison at POC-1 and POC-2 is illustrated in Figure 1 and Figure 2, respectively, in both normal and logarithmic scale.

As can be seen in Figure 1 and Figure 2,the FDCs for the proposed condition with the HMP facilities is within 110% of the curve for the existing condition in both peak and duration. The additional runoff volume generated from developing the site will be released to the existing point of discharge at a flow rate below the 10% Q2 lower threshold. Additionally,the project will also not increase peak flow rates between the pre-development Q2 and the Qio, as shown in the graphic and also in the peak flow tables listed in Attachment 1.

Discussion of the Manning's coefficient(Pervious Areas)for Pre and Post-Development Conditions Typically the Manning's coefficient is selected as n = 0.15 for pervious areas and n =0.012 for impervious areas (as consistent with the BMP Design Manual). However, due to the impact that n has in the continuous simulation a more accurate value of the Manning's coefficient has been chosen for pervious areas. Taken into consideration the study prepared by Tory R. Walker Engineering (Reference [6]) a value of n =0.08 has been selected (see Table 1 of Reference [6] included in Attachment 7). The existing condition site includes paved driveways and impervious accessory buildings. Existing impervious areas are assumed to be pervious areas consisting of the bare soil underlying the impervious surfaces. Therefore the existing condition site is primarily a mix of bare dirt and shrubs.

Based on these existing site observations, the N value was conservatively selected as 0.08, which is consistent per the reference cited. The BMP Design Manual default value of n =0.10 was used for the developed portions of the project, as the developed site is assumed to include dense landscaping.

DRAWDOWN TIME
To ensure compliance with the 24 hour and 96 hour drawdown requirements (per Section 6.3.7 of the BMP Design Manual); drawdown calculations are provided in Attachment 10 of this report.

SUMMARY
This study has demonstrated that the proposed biofiltration basins provided for the Camino Largo Project site are sufficient to meet current HMP criteria if the cross-section areas and volumes recommended within this document, and the respective orifice and outlet structures are incorporated as specified within the proposed project site.

KEY ASSUMPTIONS

1. No infiltration test were performed. Infiltration for the site is considered low and within the range of Type D soils.

2. The biofiltration basins will be lined with an impermeable liner (no infiltration).

ATTACHMENTS

1. Q2 to Q10 Comparison Tables

2. FDC Plots (log and natural "x" scale) and Flow Duration Table

3. List of the "n" largest Peaks: Pre-Development and Post-Development Conditions

4. Elevations vs. Discharge &Stage-Storage Curves to be used in SWMM

5. Basin Outlet Structure Details

6. SWMM Input Data in Input Format (Existing and Proposed Models)

7. SWMM Screens and Explanation of Significant Variables

8. Geotechnical Documentation

9. Summary files from the SWMM Model

10. Drawdown calculations

REFERENCES
[1]—"City of Vista BMP Design Manual",June 2016, City of Vista. [2]—"Final Hydromodification Management Plan (HMP)prepared for the County of San Diego", March 2011, Brown and Caldwell.
[3]—Order R9-2013-001, California Regional Water Quality Control Board San Diego Region (SDRWQCB). [4]—"Review and Analysis of San Diego County Hydromodification Management Plan (HMP):Assumptions, Criteria, Methods, & Modeling Tools—Prepared for the Cities of San Marcos, Oceanside& Vista", May 2012,Tory R. Walker Engineering.
[5]—"San Diego County Hydraulic Design Manual', September 2014, County of San Diego Department of Public Works Flood Control Section.
[6]—"Improving Accuracy in Continuous Hydrologic Modeling:Guidance for Selecting Pervious Overland Flow Manning's n Value in the San Diego Region",Tory R. Walker Engineering, 2016. [7]— "Priority Development Project(PDP)Storm Water Quality Management Plan (SWQMP)for 1017 Sycamore Avenue", March 18, 2020, BHA, Inc.

Figure 1a and 1b. POG1 Flow Duration Curve Comparison (logarithmic and normal "x"scale) Camino Largo,Vista,Ca-POC-1 Flow Duration Curve

5.000

4.500

4.000

3.500

3.000
i
o �t

2.500
t

2.000 �J

1.500

1.000 -

0.500 ---Pre-project Q
Post-project(Mitigated)Q

0.000

1.0E-06 1.0E-05 1.0E-04 1.0E-03
%Time Exceeding
Camino Largo,Vista,Ca-POC-1 Flow Duration Curve

5.000

4.500

4.000

3.500
L^

3.000
3 0

2.500

2.000

1.500

1.000

0.500 ---Pre-project Q
Post-project(Mitigated)Q

0.000

1.0E-06 1.0E-05 1.0E-04 1.0E-03
%Time Exceeding

Figure 2a and 2b. PCIC-2 Flow Duration Curve Comparison (logarithmic and normal "x"scale) Camino Largo,Vista,Ca-POC-2 Flow Duration Curve

3.500

3.000

2.500
3 2.000

1.500

1.000

0.500
---Pre-projectQ
Post-project(Mitigated)Q

0.000

1.0E-06 1.0E-05 1.0E-04 1.0E-03
%Time Exceeding
Camino Largo,Vista,Ca POC-2 Flow Duration Curve

8.000

7.000

6.000

5.000 __
-Pre-project Q
-Post-project(Mitigated)Q
3 0
W 4.000
i

3.000

2.000

1.000

0.000

3.0E-08 3.1E-04 6.2E-04 9.3E-04 1.2E-03 1.6E-03 1.9E-03 %Time Exceeding

ATTACHMENT 1
Qz to Qso Comparison Tables
11 Peak Flow Frequency Summary- POC-1
Q2 to Qlo Comparison Table-POC-1
Return Period Existing Condition (cfs) Mitigated Condition Reduction, Exist- (cfs) Mitigated (cfs)
LF=0.1xQ2 1.318 0.987 0.331
2-year 2.635 1.973 0.662
3-year 2.847 2.317 0.530
4-year 3.262 2.696 0.566
5-year 3.346 2.914 0.432
6-year 3.446 3.051 0.395
7-year 3.648 3.132 0.517
8-year 3.737 3.160 0.577
9-year 3.985 3.169 0.817
10-year 4.249 3.216 1.033
Peak Flow Frequency Summary- POC-2
Q2 to Qlo Comparison Table- POC-2
Return Period Existing Condition (cfs) Mitigated Condition Reduction, Exist- (cfs) Mitigated (cfs)
LF = 0.1xQ2 1.112 0.474 0.638
2-year 2.224 0.948 1.276
3-year 2.398 1.032 1.366
4-year 2.744 1.166 1.578
5-year 2.825 1.208 1.617
6-year 2.896 1.247 1.648
7-year 3.063 1.315 1.748
8-year 3.138 1.349 1.789
9-year 3.369 1.427 1.942
10-year 3.603 1.513 2.090

ATTACHMENT 2
FDC Plots (log and natural 'Y' scale) and Flow Duration Table

Flow Duration Curve Analysis
1) Flow duration curve shall not exceed the existing conditions by more than 10%, neither in peak flow nor duration.

The figures on the following pages illustrate that the flow duration curve in post-development conditions after the proposed BMP is below the existing flow duration curve. The flow duration curve table following the curve shows that if the interval 0.1Q2 — Q10 is divided into 100 sub intervals, the post development divided by pre-development durations is never larger than 110% (the permit allows up to 110%) Consequently,the design passes the hydromodification test.

It is important to note that the flow duration curve can be expressed in the"x" axis as percentage of time, hours per year, total number of hours, or any other similar time variable. As those variables only differ by a multiplying constant,their plot in logarithmic scale is going to look exactly the same, and compliance can be observed regardless of the variable selected. However, in order to satisfy the County of San Diego HMP example, %of time exceeded is the variable of choice in the flow duration curve. The selection of a logarithmic scale in lieu of the normal scale is preferred,as differences between the pre-development and post-development curves can be seen more clearly in the entire range of analysis. Both graphics are presented just to prove the difference.

In terms of the "y" axis,the peak flow value is the variable of choice. As an additional analysis performed by BHA, not only the range of analysis is clearly depicted (50%of Q2 to Qio) but also all intermediate flows are shown (Q2, Q3, Q4, Qs, Q6, Q7, Qs, and Q9) in order to demonstrate compliance at any range Qx—Q,1.

It must be pointed out that one of the limitations of both the SWMM and SDHM models is that the intermediate analysis is not performed (to obtain Q;from i = 2 to 10). BHA performed the analysis using the Weibull Plotting positon Method from the "n" largest independent peak flows obtained from the continuous time series.

The largest "n" peak flows are attached in this appendix, as well as the values of Q, with a return period "i",from i = 2 to 10. The Q,values are also added into the flow-duration plot.

Flow Duration Curve Data for Camino Largo POC-1, Vista, CA Low Flow Threshold: 50%

0.1xQ2(Pre): 1.318 cfs
Q10(Pre): 4.249 cfs
#of Ordinates: 100
Incremental Q(Pre): 0.02931 cfs
Total Hourly Data: 497370 hours The proposed BMP: PASSED Pre-project Post-project
Pre-project Pre-project Post-project
Interval Flow(cfs) Hours %Time Hours %Time Percentage Pass/Fail Exceeding Exceeding
0 1.318 145 2.92E-04 79 1.59E-04 54% Pass
1 1.347 134 2.69E-04 72 1.45E-04 54% Pass
2 1.376 126 2.53E-04 68 1.37E-04 54% Pass
3 1.405 126 2.53E-04 64 1.29E-04 51% Pass
4 1.435 120 2.41E-04 61 1.23E-04 51% Pass
5 1.464 117 2.35E-04 58 1.17E-04 50% Pass
6 1.493 116 2.33E-04 55 1.11E-04 47% Pass
7 1.523 113 2.27E-04 54 1.09E-04 48% Pass
8 1.552 111 2.23E-04 54 1.09E-04 49% Pass
9 1.581 110 2.21E-04 54 1.09E-04 49% Pass
10 1.611 103 2.07E-04 54 1.09E-04 52% Pass
11 1.640 98 1.97E-04 54 1.09E-04 55% Pass
12 1.669 93 1.87E-04 52 1.05E-04 56% Pass
13 1.699 89 1.79E-04 48 9.65E-05 54% Pass
14 1.728 83 1.67E-04 46 9.25E-05 55% Pass
15 1.757 81 1.63E-04 45 9.05E-05 56% Pass
16 1.786 75 1.51E-04 44 8.85E-05 59% Pass
17 1.816 71 1.43E-04 42 8.44E-05 59% Pass
18 1.845 65 1.31E-04 41 8.24E-05 63% Pass
19 1.874 64 1.29E-04 38 7.64E-05 59% Pass
20 1.904 62 1.25E-04 36 7.24E-05 58% Pass
21 1.933 62 1.25E-04 36 7.24E-05 58% Pass
22 1.962 61 1.23E-04 36 7.24E-05 59% Pass
23 1.992 58 1.17E-04 35 7.04E-05 60% Pass
24 2.021 57 1.15E-04 34 6.84E-05 60% Pass
25 2.050 54 1.09E-04 33 6.63E-05 61% Pass
26 2.080 52 1.05E-04 31 6.23E-05 60% Pass
27 2.109 49 9.85E-05 31 6.23E-05 63% Pass
15 28 2.138 48 9.65E-05 30 6.03E-05 63% Pass
29 2.168 48 9.65E-05 30 6.03E-05 63% Pass
30 2.197 46 9.25E-05 27 5.43E-05 59% Pass
31 2.226 44 8.85E-05 24 4.83E-05 55% Pass
32 2.255 42 8.44E-05 22 4.42E-05 52% Pass
33 2.285 42 8.44E-05 21 4.22E-05 50% Pass
34 2.314 41 8.24E-05 21 4.22E-05 51% Pass
35 2.343 41 8.24E-05 20 4.02E-05 49% Pass
36 2.373 40 8.04E-05 19 3.82E-05 48% Pass
37 2.402 39 7.84E-05 19 3.82E-05 49% Pass
38 2.431 39 7.84E-05 19 3.82E-05 49% Pass
39 2.461 39 7.84E-05 19 3.82E-05 49% Pass
40 2.490 37 7.44E-05 19 3.82E-05 51% Pass
41 2.519 35 7.04E-05 18 3.62E-05 51% Pass
42 2.549 33 6.63E-05 18 3.62E-05 55% Pass
43 2.578 33 6.63E-05 17 3.42E-05 52% Pass
44 2.607 33 6.63E-05 17 3.42E-05 52% Pass
45 2.637 32 6.43E-05 17 3.42E-05 53% Pass
46 2.666 31 6.23E-05 17 3.42E-05 55% Pass
47 2.695 31 6.23E-05 16 3.22E-05 52% Pass
48 2.724 30 6.03E-05 15 3.02E-05 50% Pass
49 2.754 29 5.83E-05 15 3.02E-05 52% Pass
50 2.783 25 5.03E-05 15 3.02E-05 60% Pass
51 2.812 22 4.42E-05 15 3.02E-05 68% Pass
52 2.842 22 4.42E-05 15 3.02E-05 68% Pass
53 2.871 21 4.22E-05 14 2.81E-05 67% Pass
54 2.900 21 4.22E-05 13 2.61E-05 62% Pass
55 2.930 21 4.22E-05 13 2.61E-05 62% Pass
56 2.959 21 4.22E-05 13 2.61E-05 62% Pass
57 2.988 21 4.22E-05 12 2.41E-05 57% Pass
58 3.018 21 4.22E-05 12 2.41E-05 57% Pass
59 3.047 21 4.22E-05 11 2.21E-05 52% Pass
60 3.076 21 4.22E-05 11 2.21E-05 52% Pass
61 3.106 20 4.02E-05 11 2.21E-05 55% Pass
62 3.135 20 4.02E-05 10 2.01E-05 50% Pass
63 3.164 20 4.02E-05 8 1.61E-05 40% Pass
64 3.193 19 3.82E-05 6 1.21E-05 32% Pass
65 3.223 18 3.62E-05 6 1.21E-05 33% Pass
66 3.252 15 3.02E-05 6 1.21E-05 40% Pass
67 3.281 15 3.02E-05 6 1.21E-05 40% Pass
68 3.311 13 2.61E-05 6 1.21E-05 46% Pass
69 3.340 11 2.21E-05 6 1.21E-05 55% Pass
70 3.369 10 2.01E-05 6 1.21E-05 60% Pass

71 3.399 9 1.81E-05 6 1.21E-05 67% Pass
72 3.428 9 1.81E-05 5 1.01E-05 56% Pass
73 3.457 9 1.81E-05 4 8.04E-06 44% Pass
74 3.487 9 1.81E-05 4 8.04E-06 44% Pass
75 3.516 9 1.81E-05 4 8.04E-06 44% Pass
76 3.545 9 1.81E-05 4 8.04E-06 44% Pass
77 3.575 9 1.81E-05 4 8.04E-06 44% Pass
78 3.604 8 1.61E-05 4 8.04E-06 50% Pass
79 3.633 8 1.61E-05 4 8.04E-06 50% Pass
80 3.662 8 1.61E-05 4 8.04E-06 50% Pass
81 3.692 7 1.41E-05 4 8.04E-06 57% Pass
82 3.721 7 1.41E-05 4 8.04E-06 57% Pass
83 3.750 7 1.41E-05 4 8.04E-06 57% Pass
84 3.780 6 1.21E-05 4 8.04E-06 67% Pass
85 3.809 6 1.21E-05 4 8.04E-06 67% Pass
86 3.838 6 1.21E-05 4 8.04E-06 67% Pass
87 3.868 6 1.21E-05 4 8.04E-06 67% Pass
88 3.897 6 1.21E-05 4 8.04E-06 67% Pass
89 3.926 6 1.21E-05 4 8.04E-06 67% Pass
90 3.956 6 1.21E-05 4 8.04E-06 67% Pass
91 3.985 6 1.21E-05 4 8.04E-06 67% Pass
92 4.014 6 1.21E-05 4 8.04E-06 67% Pass
93 4.044 6 1.21E-05 4 8.04E-06 67% Pass
94 4.073 6 1.21E-05 4 8.04E-06 67% Pass
95 4.102 6 1.21E-05 4 8.04E-06 67% Pass
96 4.131 6 1.21E-05 4 8.04E-06 67% Pass
97 4.161 6 1.21E-05 4 8.04E-06 67% Pass
98 4.190 6 1.21E-05 4 8.04E-06 67% Pass
99 4.219 5 1.01E-05 4 8.04E-06 80% Pass
100 4.249 5 1.01E-05 4 8.04E-06 80% Pass

Peak flows calculated with the Weibull Plotting Position Return Period Pre-Dev. Peak Post-Dev. Reduction
(years) Flows (cfs) Peak Flows(cfs) (cfs)
LF=0.1xQ2 1.318 0.987 0.331
2-year 2.635 1.973 0.662
3-year 2.847 2.317 0.530
4-year 3.262 2.696 0.566
5-year 3.346 2.914 0.432
6-year 3.446 3.051 0.395
7-year 3.648 3.132 0.517
8-year 3.737 3.160 0.577
9-year 3.985 3.169 0.817
10-year 4.249 3.216 1.033

Flow Duration Curve Data for Camino Largo POC-2, Vista, CA Low Flow Threshold: 50%

0.1xQ2(Pre): 1.112 cfs
Q10(Pre): 3.603 cfs
#of Ordinates: 100
Incremental Q(Pre): 0.02491 cfs
Total Hourly Data: 497370 hours The proposed BMP: PASSED Pre-project Post-project
Pre-project Pre-project Post-project
Interval Flow(cfs) Hours Hours%Time %Time Percentage Pass/Fail Exceeding Exceeding
0 1.112 149 3.00E-04 21 4.22E-05 14% Pass
1 1.137 139 2.79E-04 18 3.62E-05 13% Pass
2 1.162 130 2.61E-04 16 3.22E-05 12% Pass
3 1.187 127 2.55E-04 14 2.81E-05 11% Pass
4 1.212 123 2.47E-04 11 2.21E-05 9% Pass
5 1.237 120 2.41E-04 9 1.81E-05 8% Pass
6 1.261 117 2.35E-04 9 1.81E-05 8% Pass
7 1.286 116 2.33E-04 9 1.81E-05 8% Pass
8 1.311 113 2.27E-04 8 1.61E-05 7% Pass
9 1.336 110 2.21E-04 7 1.41E-05 6% Pass
10 1.361 106 2.13E-04 6 1.21E-05 6% Pass
11 1.386 100 2.01E-04 6 1.21E-05 6% Pass 12 1.411 94 1.89E-04 6 1.21E-05 6% Pass
13 1.436 90 1.81E-04 6 1.21E-05 7% Pass
14 1.461 86 1.73E-04 6 1.21E-05 7% Pass
15 1.486 80 1.61E-04 6 1.21E-05 8% Pass
16 1.511 74 1.49E-04 5 1.01E-05 7% Pass
17 1.535 71 1.43E-04 5 1.01E-05 7% Pass
18 1.560 67 1.35E-04 5 1.01E-05 7% Pass
19 1.585 66 1.33E-04 5 1.01E-05 8% Pass
20 1.610 65 1.31E-04 5 1.01E-05 8% Pass
21 1.635 62 1.25E-04 4 8.04E-06 6% Pass 22 1.660 62 1.25E-04 4 8.04E-06 6% Pass 23 1.685 59 1.19E-04 4 8.04E-06 7% Pass
24 1.710 57 1.15E-04 3 6.03E-06 5% Pass
25 1.735 54 1.09E-04 2 4.02E-06 4% Pass
26 1.760 50 1.01E-04 2 4.02E-06 4% Pass
27 1.785 50 1.01E-04 2 4.02E-06 4% Pass

28 1.809 49 9.85E-05 2 4.02E-06 4% Pass
29 1.834 48 9.65E-05 2 4.02E-06 4% Pass
30 1.859 46 9.25E-05 1 2.01E-06 2% Pass
31 1.884 44 8.85E-05 1 2.01E-06 2% Pass
32 1.909 43 8.65E-05 1 2.01E-06 2% Pass
33 1.934 42 8.44E-05 0 0.00E+00 0% Pass
34 1.959 41 8.24E-05 0 0.00E+00 0% Pass
35 1.984 41 8.24E-05 0 0.00E+00 0% Pass
36 2.009 40 8.04E-05 0 0.00E+00 0% Pass
37 2.034 39 7.84E-05 0 0.00E+00 0% Pass
38 2.059 39 7.84E-05 0 0.00E+00 0% Pass
39 2.083 39 7.84E-05 0 0.00E+00 0% Pass
40 2.108 37 7.44E-05 0 0.00E+00 0% Pass
41 2.133 35 7.04E-05 0 0.00E+00 0% Pass
42 2.158 33 6.63E-05 0 0.00E+00 0% Pass
43 2.183 33 6.63E-05 0 0.00E+00 0% Pass
44 2.208 33 6.63E-05 0 0.00E+00 0% Pass
45 2.233 32 6.43E-05 0 0.00E+00 0% Pass
46 2.258 31 6.23E-05 0 0.00E+00 0% Pass
47 2.283 31 6.23E-05 0 0.00E+00 0% Pass
48 2.308 29 5.83E-05 0 0.00E+00 0% Pass
49 2.333 29 5.83E-05 0 0.00E+00 0% Pass
50 2.357 22 4.42E-05 0 0.00E+00 0% Pass
51 2.382 22 4.42E-05 0 0.00E+00 0% Pass
52 2.407 22 4.42E-05 0 0.00E+00 0% Pass
53 2.432 21 4.22E-05 0 0.00E+00 0% Pass
54 2.457 21 4.22E-05 0 0.00E+00 0% Pass
55 2.482 21 4.22E-05 0 0.00E+00 0% Pass
56 2.507 21 4.22E-05 0 0.00E+00 0% Pass
57 2.532 21 4.22E-05 0 0.00E+00 0% Pass
58 2.557 21 4.22E-05 0 0.00E+00 0% Pass
59 2.582 21 4.22E-05 0 0.00E+00 0% Pass
60 2.607 21 4.22E-05 0 0.00E+00 0% Pass
61 2.631 20 4.02E-05 0 0.00E+00 0% Pass
62 2.656 20 4.02E-05 0 0.00E+00 0% Pass
63 2.681 19 3.82E-05 0 0.00E+00 0% Pass
64 2.706 18 3.62E-05 0 0.00E+00 0% Pass
65 2.731 15 3.02E-05 0 0.00E+00 0% Pass
66 2.756 15 3.02E-05 0 0.00E+00 0% Pass
67 2.781 13 2.61E-05 0 0.00E+00 0% Pass
68 2.806 12 2.41E-05 0 0.00E+00 0% Pass
69 2.831 11 2.21E-05 0 0.00E+00 0% Pass
70 2.856 9 1.81E-05 0 0.00E+00 0% Pass

71 2.881 9 1.81E-05 0 0.00E+00 0% Pass
72 2.905 9 1.81E-05 0 0.00E+00 0% Pass
73 2.930 9 1.81E-05 0 0.00E+00 0% Pass
74 2.955 9 1.81E-05 0 0.00E+00 0% Pass
75 2.980 9 1.81E-05 0 0.00E+00 0% Pass
76 3.005 9 1.81E-05 0 0.00E+00 0% Pass
77 3.030 8 1.61E-05 0 0.00E+00 0% Pass
78 3.055 8 1.61E-05 0 0.00E+00 0% Pass
79 3.080 8 1.61E-05 0 0.00E+00 0% Pass
80 3.105 7 1.41E-05 0 0.00E+00 0% Pass
81 3.130 7 1.41E-05 0 0.00E+00 0% Pass
82 3.155 7 1.41E-05 0 0.00E+00 0% Pass
83 3.179 6 1.21E-05 0 0.00E+00 0% Pass
84 3.204 6 1.21E-05 0 0.00E+00 0% Pass
85 3.229 6 1.21E-05 0 0.00E+00 0% Pass
86 3.254 6 1.21E-05 0 0.00E+00 0% Pass
87 3.279 6 1.21E-05 0 0.00E+00 0% Pass
88 3.304 6 1.21E-05 0 0.00E+00 0% Pass
89 3.329 6 1.21E-05 0 0.00E+00 0% Pass
90 3.354 6 1.21E-05 0 0.00E+00 0% Pass
91 3.379 6 1.21E-05 0 0.00E+00 0% Pass
92 3.404 6 1.21E-05 0 0.00E+00 0% Pass
93 3.429 6 1.21E-05 0 0.00E+00 0% Pass
94 3.453 6 1.21E-05 0 0.00E+00 0% Pass
95 3.478 6 1.21E-05 0 0.00E+00 0% Pass
96 3.503 6 1.21E-05 0 0.00E+00 0% Pass
97 3.528 6 1.21E-05 0 0.00E+00 0% Pass
98 3.553 6 1.21E-05 0 0.00E+00 0% Pass
99 3.578 5 1.01E-05 0 0.00E+00 0% Pass
100 j 3.603 j 5 j 1.01E-05 j 0 j 0.00E+00 j 0% j Pass

Peak flows calculated with the Weibull Plotting Position Return Period Pre-Dev. Peak Post-Dev. Reduction
(years) Flows (cfs) Peak Flows(cfs) (cfs)
LF=0.1xQ2 1.112 0.474 0.638
2-year 2.224 0.948 1.276
3-year 2.398 1.032 1.366
4-year 2.744 1.166 1.578
5-year 2.825 1.208 1.617
6-year 2.896 1.247 1.648
7-year 3.063 1.315 1.748
8-year 3.138 1.349 1.789
9-year 3.369 1.427 1.942
10-year 3.603 1.513 2.090

ATTACHMENT 3
List of the "n" largest Peaks: Pre-Development and Post-Development Conditions

List of the "n" Largest Peaks: Pre & Post-Developed Conditions • Basic Probabilistic Equation: R = P
where,
R = Return period in years; and
P = Probability of a flow to be equaled or exceeded any given year (dimensionless). • Weibull Equation: P = i n
where,
i = Position of the peak whose probability is desired (sorted from large to small); and n = number of years analyzed.

Explanation of Variables for the Tables in this Attachment • Peak: Refers to the peak flow at the date given, taken from the continuous simulation hourly results of the n year analyzed.
• Posit: If all peaks are sorted from large to small, the position of the peak in a sorting analysis is included under the variable Posit.
• Date: Date of the occurrence of the peak at the outlet form the continuous simulation. • Note: All peaks are not annual maxima; instead they are defined as event maxima, with a threshold to separate peaks of at least 12 hours. In other words, any peak P in a time series is defined as a value where dP/dt=0, and the peak is the largest value in 25 hours (12 hours before the hour of occurrence and 12 hours after the occurrence, so it is in essence a daily peak).

Pre-Project Flow Frequency for POC-1 - Long-term Simulation Camino Largo,Vista,CA, Pre-Developed Runoff Condition, POC-1 Statistics- Node POC-1 Total Inflow
Event Event Exceedance Return
Duration Peak Frequency Period
Rank Start Date (hours) (CFS) (percent) (years) 1 4/14/2003 8 5.563 0.28 58
2 1/4/1978 3 5.189 0.55 29
3 10/1/1983 3 4.985 0.83 19.33
4 1/15/1979 4 4.679 1.11 14.5
5 1/4/1995 7 4.509 1.39 11.6
6 9/23/1986 1 4.195 1.66 9.67
7 2/25/2003 6 3.763 1.94 8.29
8 2/3/1958 31 3.67 2.22 7.25
9 2/24/1969 45 3.6 2.49 6.44
10 10/27/2004 8 3.376 2.77 5.8
11 1/13/1993 10 3.358 3.05 5.27
12 10/29/2000 2 3.339 3.32 4.83
13 2/18/2005 19 3.325 3.6 4.46
14 2/20/1980 13 3.284 3.88 4.14
15 3/17/1982 17 3.241 4.16 3.87
16 1/16/1952 8 3.226 4.43 3.63
17 2/28/1978 16 3.199 4.71 3.41
18 4/1/1958 9 3.184 4.99 3.22
19 3/2/1980 14 2.87 5.26 3.05
20 2/10/1978 4 2.802 5.54 2.9
21 12/29/1991 13 2.793 5.82 2.76
22 11/22/1965 25 2.79 6.09 2.64
23 2/27/1983 4 2.779 6.37 2.52
24 1/29/1983 4 2.777 6.65 2.42
25 2/3/1998 7 2.776 6.93 2.32
26 12/19/1970 20 2.725 7.2 2.23
27 1/27/2008 21 2.698 7.48 2.15
28 2/22/1998 34 2.646 7.76 2.07
29 2/16/1980 3 2.635 8.03 2
30 10/20/2004 6 2.527 8.31 1.93
31 11/15/1952 2 2.526 8.59 1.87
32 2/16/1998 31 2.495 8.86 1.81
33 11/11/1985 5 2.495 9.14 1.76
34 2/18/1993 1 2.474 9.42 1.71
35 12/1/1961 19 2.473 9.7 1.66
36 2/3/1994 12 2.384 9.97 1.61

37 1/15/1993 76 2.349 10.25 1.57
38 1/16/1978 9 2.31 10.53 1.53
39 3/11/1995 23 2.249 10.8 1.49
40 1/5/2008 45 2.244 11.08 1.45
41 2/14/1986 7 2.225 11.36 1.41
42 1/28/1980 26 2.217 11.63 1.38
43 2/14/1998 9 2.193 11.91 1.35
44 3/17/1963 3 2.177 12.19 1.32
45 3/15/1986 22 2.136 12.47 1.29
46 2/12/1992 15 2.103 12.74 1.26
47 2/22/2008 8 2.066 13.02 1.23
48 1/16/1972 3 2.058 13.3 1.21
49 2/27/1991 41 2.049 13.57 1.18
50 3/19/1981 2 2.036 13.85 1.16
51 4/27/1960 4 2.027 14.13 1.14
52 12/22/1982 1 1.999 14.4 1.12
53 2/8/1993 10 1.977 14.68 1.09
54 2/11/2003 27 1.937 14.96 1.07
55 2/6/1969 9 1.878 15.24 1.05
56 8/17/1977 2 1.873 15.51 1.04
57 1/11/2005 9 1.842 15.79 1.02
58 4/28/2005 1 1.832 16.07 1
Pre-project
10-year Q: cfs
5-year Q:121
cfs
2-year Q: cfs
Lower Flow Threshold 50%

0.1xQ2(Pre): 1.318 cfs

Pre-Project Flow Frequency for POC-2 - Long-term Simulation Camino Largo,Vista, CA, Pre-Developed Runoff Condition, POC 2 Statistics- Node POC-2 Total Inflow
Event Event Exceedance Return
Duration Peak Frequency Period
Rank Start Date (hours) (CFS) (percent) (years) 1 4/14/2003 8 4.668 0.27 58
2 1/4/1978 3 4.361 0.55 29
3 10/1/1983 3 4.183 0.82 19.33 4 1/15/1979 4 3.925 1.1 14.5 5 1/4/1995 6 3.782 1.37 11.6
6 9/23/1986 1 3.566 1.64 9.67
7 2/25/2003 6 3.16 1.92 8.29
8 2/3/1958 31 3.081 2.19 7.25 9 2/24/1969 45 3.022 2.47 6.44 10 10/27/2004 7 2.838 2.74 5.8
11 1/13/1993 10 2.834 3.01 5.27 12 10/29/2000 2 2.82 3.29 4.83
13 2/18/2005 19 2.794 3.56 4.46 14 2/20/1980 13 2.757 3.84 4.14 15 3/17/1982 17 2.731 4.11 3.87 16 1/16/1952 8 2.71 4.38 3.63
17 2/28/1978 16 2.688 4.66 3.41 18 4/1/1958 9 2.68 4.93 3.22
19 3/2/1980 14 2.421 5.21 3.05 20 2/10/1978 4 2.352 5.48 2.9 21 12/29/1991 13 2.347 5.75 2.76 22 11/22/1965 25 2.346 6.03 2.64 23 2/27/1983 4 2.344 6.3 2.52 24 1/29/1983 4 2.343 6.58 2.42 25 2/3/1998 7 2.333 6.85 2.32
26 12/19/1970 20 2.298 7.12 2.23 27 1/27/2008 21 2.289 7.4 2.15 28 2/16/1980 3 2.236 7.67 2.07
29 2/22/1998 34 2.224 7.95 2
30 11/15/1952 2 2.15 8.22 1.93
31 10/20/2004 6 2.148 8.49 1.87
32 11/11/1985 5 2.133 8.77 1.81
33 2/18/1993 1 2.126 9.04 1.76
34 2/16/1998 31 2.097 9.32 1.71 35 12/1/1961 20 2.088 9.59 1.66 36 2/3/1994 12 2.031 9.86 1.61

37 1/15/1993 76 2.002 10.14 1.57
38 1/16/1978 9 1.939 10.41 1.53
39 3/11/1995 23 1.92 10.68 1.49
40 1/5/2008 45 1.894 10.96 1.45
41 2/14/1986 7 1.875 11.23 1.41
42 1/28/1980 26 1.86 11.51 1.38
43 3/17/1963 3 1.848 11.78 1.35
44 2/14/1998 9 1.845 12.05 1.32
45 3/15/1986 22 1.809 12.33 1.29
46 2/12/1992 15 1.795 12.6 1.26
47 2/27/1991 41 1.753 12.88 1.23
48 2/22/2008 8 1.737 13.15 1.21
49 12/22/1982 1 1.732 13.42 1.18
50 1/16/1972 3 1.731 13.7 1.16
51 3/19/1981 2 1.727 13.97 1.14
52 4/27/1960 4 1.704 14.25 1.12
53 2/8/1993 10 1.677 14.52 1.09
54 2/11/2003 27 1.632 14.79 1.07
55 4/28/2005 1 1.622 15.07 1.05
56 2/6/1969 9 1.616 15.34 1.04
57 8/17/1977 2 1.574 15.62 1.02
58 1/11/2005 9 1.548 15.89 1
Pre-project
10-year Q: 3.603 cfs
5-year Q: 2.825 cfs
2-year Q: 2.224 cfs
Lower Flow Threshold 50%

0.1xQ2(Pre): 1.112 cfs

Post-Project (Mitigated) Flow Frequency for POC-1 - Long-term Simulation Camino Largo,Vista,CA Post-Developed Mitigated Runoff Condition- POC-1 Statistics- Node POC-1 Total Inflow
Event Event Exceedance Return
Duration Peak Frequency Period
Rank Start Date (hours) (CFS) (percent) (years) 1 4/14/2003 38 5.217 0.11 58
2 9/29/1983 50 4.79 0.22 29
3 1/3/1995 45 4.515 0.34 19.33
4 1/14/1979 33 4.504 0.45 14.5
5 1/3/1978 74 3.443 0.56 11.6
6 2/25/2003 68 3.169 0.67 9.67
7 9/23/1986 35 3.168 0.78 8.29
8 10/27/2004 34 3.138 0.9 7.25
9 2/23/1969 55 3.117 1.01 6.44
10 2/27/1978 142 3.021 1.12 5.8
11 2/3/1958 38 2.967 1.23 5.27
12 2/13/1980 190 2.881 1.35 4.83
13 1/16/1952 53 2.857 1.46 4.46
14 2/5/1978 209 2.721 1.57 4.14
15 3/2/1980 22 2.672 1.68 3.87
16 2/18/2005 33 2.558 1.79 3.63
17 3/17/1982 45 2.502 1.91 3.41
18 1/16/1978 14 2.354 2.02 3.22
19 1/27/1980 67 2.337 2.13 3.05
20 11/22/1965 29 2.277 2.24 2.9
21 8/16/1977 30 2.226 2.35 2.76
22 2/20/2008 54 2.21 2.47 2.64
23 2/3/1998 40 2.203 2.58 2.52
24 1/16/1972 15 2.193 2.69 2.42
25 10/29/2000 28 2.183 2.8 2.32
26 12/16/1970 75 2.114 2.91 2.23
27 12/29/1991 15 2.032 3.03 2.15
28 1/12/1993 151 2.005 3.14 2.07
29 2/22/1998 69 1.973 3.25 2
30 3/31/1958 107 1.88 3.36 1.93
31 2/14/1986 14 1.877 3.48 1.87
32 1/5/1979 33 1.849 3.59 1.81
33 1/14/1978 19 1.848 3.7 1.76
34 3/7/1968 18 1.811 3.81 1.71
35 1/20/1962 59 1.792 3.92 1.66
36 4/27/1960 11 1.775 4.04 1.61

37 2/16/1998 43 1.716 4.15 1.57
38 1/7/2005 119 1.702 4.26 1.53
39 11/11/1985 29 1.693 4.37 1.49
40 12/28/2004 53 1.692 4.48 1.45
41 11/17/1986 18 1.686 4.6 1.41
42 11/14/1952 45 1.676 4.71 1.38
43 3/24/1994 25 1.651 4.82 1.35
44 3/16/1963 24 1.649 4.93 1.32
45 2/26/1983 165 1.478 5.04 1.29
46 3/11/1995 27 1.46 5.16 1.26
47 12/24/1988 9 1.451 5.27 1.23
48 2/26/2004 13 1.426 5.38 1.21
49 2/1/1960 11 1.412 5.49 1.18
50 12/3/1966 93 1.408 5.61 1.16
51 12/18/1967 44 1.39 5.72 1.14
52 1/12/1960 10 1.387 5.83 1.12
53 1/3/2005 55 1.38 5.94 1.09
54 1/28/1983 15 1.35 6.05 1.07
55 9/17/1963 44 1.342 6.17 1.05
56 1/13/1957 12 1.332 6.28 1.04
57 1/5/2008 54 1.28 6.39 1.02
58 11/21/1996 18 1.243 6.5 1
Post-project (Mitigated)
10-year Q: 3.216 cfs
5-year Q: 2.914 cfs
2-year Q: 1.973 cfs
Lower Flow Threshold 50%

0.1xQ2(Pre): 0.987 cfs

Post-Project (Mitigated) Flow Frequency for POC-2 - Long-term Simulation Camino Largo,Vista,CA Post-Developed Mitigated Runoff Condition- POC 2 Statistics- Node POC-1 Total Inflow
Event Event Exceedance Return
Duration Peak Frequency Period
Rank Start Date (hours) (CFS) (percent) (years) 1 4/14/2003 5 1.912 0.3 58
2 1/4/1978 3 1.852 0.61 29
3 10/1/1983 2 1.714 0.91 19.33
4 1/15/1979 4 1.693 1.22 14.5
5 1/4/1995 6 1.618 1.52 11.6
6 9/23/1986 1 1.491 1.83 9.67
7 2/25/2003 4 1.359 2.13 8.29
8 2/3/1958 30 1.322 2.44 7.25
9 2/24/1969 44 1.299 2.74 6.44
10 1/13/1993 9 1.224 3.05 5.8
11 10/27/2004 7 1.219 3.35 5.27
12 2/18/2005 3 1.201 3.66 4.83
13 2/20/1980 12 1.188 3.96 4.46
14 10/29/2000 2 1.166 4.27 4.14
15 1/16/1952 7 1.166 4.57 3.87
16 2/28/1978 14 1.162 4.88 3.63
17 4/1/1958 6 1.154 5.18 3.41
18 3/17/1982 17 1.123 5.49 3.22
19 3/2/1980 14 1.037 5.79 3.05
20 2/10/1978 4 1.023 6.1 2.9
21 2/27/1983 1 1.017 6.4 2.76
22 1/29/1983 4 1.015 6.71 2.64
23 11/22/1965 20 1.013 7.01 2.52
24 2/3/1998 4 1.008 7.32 2.42
25 1/27/2008 20 1 7.62 2.32
26 2/16/1980 3 0.98 7.93 2.23
27 12/29/1991 10 0.964 8.23 2.15
28 2/22/1998 28 0.963 8.54 2.07
29 12/19/1970 1 0.948 8.84 2
30 2/16/1998 26 0.91 9.15 1.93
31 2/18/1993 1 0.906 9.45 1.87
32 11/15/1952 1 0.901 9.76 1.81
33 11/11/1985 3 0.901 10.06 1.76
34 10/20/2004 6 0.898 10.37 1.71
35 1/18/1993 6 0.885 10.67 1.66
36 12/2/1961 14 0.863 10.98 1.61

37 1/28/1980 27 0.862 11.28 1.57
38 3/11/1995 22 0.852 11.59 1.53
39 2/3/1994 12 0.851 11.89 1.49
40 3/15/1986 23 0.848 12.2 1.45
41 1/16/1978 5 0.847 12.5 1.41
42 1/5/2008 43 0.83 12.8 1.38
43 2/14/1986 7 0.818 13.11 1.35
44 2/14/1998 4 0.803 13.41 1.32
45 2/12/1992 14 0.797 13.72 1.29
46 2/27/1991 41 0.781 14.02 1.26
47 3/17/1963 3 0.771 14.33 1.23
48 2/22/2008 7 0.765 14.63 1.21
49 1/16/1972 2 0.765 14.94 1.18
50 12/22/1982 1 0.749 15.24 1.16
51 2/8/1993 10 0.743 15.55 1.14
52 2/6/1969 7 0.731 15.85 1.12
53 4/28/2005 1 0.727 16.16 1.09
54 3/19/1981 1 0.72 16.46 1.07
55 4/27/1960 2 0.7 16.77 1.05
56 12/31/2004 2 0.69 17.07 1.04
57 1/11/2005 7 0.682 17.38 1.02
58 3/1/1983 65 0.676 17.68 1
Post-project (Mitigated)
10-year Q:llcfs
cfs
5-year Q: cfs
2-year Q:

Lower Flow Threshold 50%

0.1xQ2(Pre): 0.474 cfs

ATTACHMENT 4
Elevation vs. Area Curves and Elevation vs. Discharge Curves to be used in SWMM

Elevation vs. Area
The elevation vs. area curves in the model are calculated in Excel and imported into the model. The summary of elevation vs. area for each BMP has been provided on the following pages.

The LID surface storage depth beneath the lowest surface discharge structure is accounted for in the LID module as illustrated in Attachment 7.

Elevation vs. Discharge
The total elevation vs.discharge curve is imported from an Excel spreadsheet that calculates the elevation vs. discharge of the outlet system. Elevation vs. discharge relationships are provided in the surface discharge of the biofiltration basin as this is where a Modified Puls routing procedure will be applied in the continuous simulation model.

The low-flow orifice size has been selected to maximum its size while still restricting flows to conform with the required 50%of the Qz event flow as mandated in the Final Hydromodification Management Plan by Brown &Caldwell, dated March 2011. While BHA acknowledges that this orifice is small, to increase the size of these outlets would impact the basin's ability to restrict flows beneath the HMP thresholds, thus preventing the BMP from conforming with HMP requirements.

In order to further reduce the risk of blockage of the orifice, regular maintenance of the riser and orifice must be performed to ensure potential blockages are minimized. A detail of the orifice and riser structures are provided in Attachment 5 of this memorandum.

Discharge Equations
The following equations are based on the San Diego County Hydraulic Design Manual(September 2014):
• Weir:
1 ` w = Cw * L * H3/2 (1)
• Slot:

As an orifice: Qs = Bs * hs * cg * 2g(H —ZS) (2.a) Asa weir: QS = CW *BS * H3/2 (2.b)
For H > hs slot works as weir until orifice equation provides a smaller discharge. The elevation such that equation (2.a) =equation (2.b) is the elevation at which the behavior changes from weir to orifice.
• Vertical Orifices:

As an orifice: Qo = 0.25 * 7CD2 * cg * 2g(H —°) (3.a) Asa weir: Critical depth and geometric family of circular sector must be solved to determine Q as a function of H:

Eo — —cr.H = Ycr + Acr ;Tcr = 2 Ycr(D —Ycr);Acr — DZ [acr — sin(acr)]; 9 Tcr 2*Tcr 8
Ycr = D[1 — sin(0.5 * acr)] (3.b.1, 3.b.2, 3.b.3, 3.b.4 and 3.b.5) There is a value of H (approximately H=110%D)from which orifices no longer work as weirs as critical depth is not possible at the entrance of the orifice. This value of H is obtained equaling the discharge using critical equations and equations (3.b).

A mathematical model is prepared with the previous equations depending on the type of discharge.

The following are the variables used above:

Qw,Qs.Qo : Discharge of weir, slot or orifice (cfs)
Cw,cg: Coefficients of discharge of weir(typically 3.1) and orifice (0.61 to 0.62) L,BS,D,hs: Length of weir, width of slot, diameter of orifice and height of slot, respectively; (ft) H: Level of water in the pond over the invert of slot, weir or orifice (ft) Acr,Tcr.Ycr.acr: Critical variables for circular sector: area (sq-ft), top width (ft), critical depth (ft), and angle to the center, respectively.

Stage-Area for Basin 1
Elevation vs. Area Tables
Depth (ft) Area (ft 2) Volume (ft)

0.000 6147 0

0.083 6173 514

0.167 6199 1033

0.250 6225 1556

0.333 6250 2083

0.417 6276 2615

0.500 6302 3151

0.583 6328 3691

0.667 6354 4236

0.750 6380 4785

0.833 6405 5338

0.917 6431 5895

1.000 6457 6457

1.083 6483 7023

1.167 6509 7593

1.250 6535 8168

1.333 6560 8747

1.417 6586 9330

1.500 6612 9918

1.583 6638 10510

1.667 6664 11106

1.750 6690 11707

1.833 6715 12311

1.917 6741 12921

2.000 6767 13534
SUB SURFACE STORAGE BASIN 1
Elevation (ft) Area(ft2) Volume (ft)
-1.50 6147 1844 Amended Soil Base (0.2voids) -2.08 6147 1434 Gravel Base (0.4voids)
Gravel &Amended Soil TOTAL= 3278 (ft 3)
Surface Total TOTAL= 4236 (ft)
BMP TOTAL= 7514 (ft)
(1):Thearea at this s urfa ce el evati on corresponds to the area of gravel and amended soil (biofiItration layer) (2):Vol ume at thi s el evation cores ponds with surface vol ume for WQ purposes (i nvert of I owest surface outlet)

Outlet Structure for Discharge of Basin 1
Elevation vs. Discharge Table
Outlet Structure for Discharge of BMP 1
Discharge vs.Elevation Table
Lower orifice Lower Slot Emergency Weir No.of orif: 0 No.of slots: 1 Invert: 1.250 ft Dia: 3 in Invert: 0.000 ft B: 20.000 ft Invert: 0.000 ft B(width): 2.833 ft V-Notch Angle 0 Area: 0.049 sf Area: 1.181 sf
Cg-low: 0.62 hsiot(height): 0.417 ft Cg-I ow: 0.62
Middle orifice Omer slot
No.of orif: 0 No.of slots: 1
Dia: 4 in Invert: 0.583 ft
Invert: 0.417 ft B(width): 0.833 ft
Area: 0.000 sf Area: 0.275 sf
Cg-low: 0.62 hsiot(height): 0.330ft
Cg-I ow: 0.62
*Note:h=head above the invert of the lowest surface discharge opening.

USE
Basin Elev. H h* Qorifice-low Qorifice-upper Qslot-low Qslot-upper Qemerg Qtot (ft) (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) 308.900 0.500 0.000 0.000 0.000 0.000 0.000 0.000 0.000 308.983 0.583 0.083 0.000 0.000 1.193 0.000 0.000 1.193 309.067 0.667 0.167 0.000 0.000 1.687 0.278 0.000 1.965 309.150 0.750 0.250 0.000 0.000 2.066 0.393 0.000 2.459 309.233 0.833 0.333 0.000 0.000 2.077 0.481 0.000 2.558 309.317 0.917 0.417 0.000 0.000 2.681 0.556 0.000 3.237 309.400 1.000 0.500 0.000 0.000 3.172 0.686 0.000 3.859 309.483 1.083 0.583 0.000 0.000 3.597 0.792 0.000 4.389 309.567 1.167 0.667 0.000 0.000 3.977 0.885 0.000 4.862 309.650 1.250 0.750 0.000 0.000 4.323 0.969 0.000 5.292 309.733 1.333 0.833 0.000 0.000 4.644 1.047 0.000 5.690 309.817 1.417 0.917 0.000 0.000 4.944 1.119 0.000 6.062 309.900 1.500 1.000 0.000 0.000 5.226 1.186 0.000 6.413 309.983 1.583 1.083 0.000 0.000 5.494 1.250 0.000 6.745 310.067 1.667 1.167 0.000 0.000 5.750 1.311 0.000 7.061 310.150 1.750 1.250 0.000 0.000 5.995 1.369 0.000 7.364 310.233 1.833 1.333 0.000 0.000 6.230 1.425 1.491 9.147 310.317 1.917 1.417 0.000 0.000 6.457 1.479 4.219 12.154 310.400 2.000 1.500 0.000 0.000 6.676 1.531 7.750 15.956 310.483 2.083 1.583 0.000 0.000 6.888 1.581 11.932 20.400 310.567 2.167 1.667 0.000 0.000 7.093 1.630 16.675 25.398 310.650 2.250 1.750 0.000 0.000 7.293 1.677 21.920 30.890 37 Camino Largo
BMP 1
Bio-Retention Cell LID
PARAMETER ABBREV. BMP
Ponding Depth PD 6 in
Bioretention Soil Layer S 18 in
Gravel Layer G 7 in
TOTAL 2.58 ft
31 in
Orifice Coefficient Cg 0.6 --
Low Flow Orifice Diameter D 4.00 in
Drain exponent n 0.5 --
Flow Rate (volumetric) Q 0.653 ft3/s
Ponding Depth Surface Area APp 6225 ft2
As, AG 6147 ft2
Bioretention Surface Area As, AG 0.141 ac
Porosity of Bioretention Soil ri 0.40 --
Flow Rate (per unit area) q 11.477 in/hr
Effective Ponding Depth PDeff 6.04 in
Flow Coefficient C 0.8596 --
Ponding Depth @ VWQ required PDorificeFL 6 in Cutoff Flow Qcutoff 0.65321 cfs

Stage-Area for Basin 2
Elevation vs. Area Tables
Depth (ft) Area (ft2) Volume (ft)

0.000 9279 0

0.083 9318 783

0.167 9358 1586

0.250 9397 2408

0.333 9436 3250

0.417 9475 4112

0.500 9515 4993

0.583 9554 5894

0.667 9593 6814

0.750 9632 7754

0.833 9672 8714

0.917 9711 9693

1.000 9750 10692

1.083 9789 11711

1.167 9829 12749

1.250 9868 13807

1.333 9907 14884

1.417 9946 15981

1.500 9986 17098

1.583 10025 18234

1.667 10064 19390

1.750 10103 20566

1.833 10143 21761

1.917 10182 22976

2.000 10221 24210
39 SUBSURFACE STORAGE BASIN 2
Elevation (ft) Area (ft) Volume (ft)
-1.50 9279 2784 Amended Soil Base (0.2voids) -2.50 9279 3712 Gravel Base (0.4voids)
Gravel &Amended Soil TOTAL= 6495 (ft)
Surface Total TOTAL= 6814 (ft)
BMP TOTAL= 13309 (ft3)
(1):The area at this s urfa ce el evati on corresponds to the area of gravel and amended soil (biofiItration layer) (2):Vol ume at thi s elevation cores ponds with s u rfa ce vol ume for WQpurposes (invertof I owest s u rfa ce outl et) Effective Depth: 6.08 in

Outlet Structure for Discharge of Basin 2
Elevation vs. Discharge Table
Outlet Structure for Discharge of BMP 2
Discharge vs.Elevation Table
Lower orifice Lower Slot Emergency Weir No.of orif: 0 No.of slots: 1 Invert: 1.000 ft Di a: 3 in Invert: 0.000 ft B: 11.830 ft Invert: 0.000 ft B(width): 2.670 ft V-Notch Angle 0 Area: 0.049 sf Area: 0.668 sf
Cg-low: 0.62 h,lot(height): 0.250ft
Cg-I ow: 0.62
Middle orifice Uoaer slot
No.of orif: 0 No.of slots: 1
Di a: 4 in Invert: 0.583 ft
Invert: 0.417 ft B(width): 0.500 ft
Area: 0.000 sf Area: 0.083 sf
Cg-low: 0.62 hslot(height): 0.167ft
Cg-I ow: 0.62
*Note:h=head above the invert of the lowest surface discharge opening.

Camino Largo
BMP2
Bio-Retention Cell LID
PARAMETER ABBREV. BMP
Ponding Depth PD 6 in
Bioretention Soil Layer S 18 in
Gravel Layer G 7 in
TOTAL 2.5833333 ft
31 in
Orifice Coefficient Cg 0.6 --
Low Flow Orifice Diameter D 3.00 in
Drain exponent n 0.5 --
Flow Rate (volumetric) Q 0.371 ft3/s
Ponding Depth Surface Area APp 9515 ft2
AS, AG 9279 ft2
Bioretention Surface Area As, AG 0.213 ac
Porosity of Bioretention Soil n 0.40 --
Flow Rate (per unit area) q 4.313 in/hr
Effective Ponding Depth PDeff 6.08 in
Flow Coefficient C 0.3203 --
Ponding Depth @ VWQ,required PDorificeFL 6 in Cutoff Flow Qcutoff 0.37058 cfs

ATTACHMENT 5
Basin Outlet Details

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VI z s gx
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ICI FL n a
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�
U) §
/ / & §} \§ § 2 2 §
} } El
2 z
A / § § ;! >3 L § §
gA3SS9A2 (B2v
,7 ■z
j B■
kd? §�
§Rv,z w:

A§
/[ ��• ��«� k
§ , r
) jI[
- - �
2 6
4 b ��|I
go
!E §§|ID K
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45 MALE NATIONAL PIPE THREAD

PVC ADAPTER CAST
IN SIDE OF RISER WALL RISER "WALL
[RAVEL 57ORAGE LAYER
UNDERDRAIN ORIFICE `k " — j---�',
THREADED FEMALE NATIONAL y�

PIPE THREAD PVC CAP
WITH DRILLED ORIFICE 6" FRENCH RFOR QED P

PERFORATED PVC PIPE
_ n
BOTTOM 0F BASIN
6'PERFORA 70 PVC PIPE `

UNDERDRAIN ORIFICE

THREADED FEMALE NATIONAL
PIPE THREAD PVC CAP z,
WITH DRILLED ORIFICE °
RESTRICTCR CAP DETAIL BMP 1 & 2

NOT TO SCALE
_ OUTLET STRUCTURE I RISER
I' �l INVERT
ELEV

UPPER SLOT OPENING IN

RISER STRUCTURE

UPPER SLOT
INVERT
Htop

LOWER SLOT OPENING IN
LOWER SLOT RISER STRUCTURE
INVERT

PONDING DEPTH

BASIN BOTTOM
CUTLET STRUCTURE DETAIL BMP 1 & 2

NOT TO SCALE

ATTACHMENT 6
SWMM Input Data in Input Format
(Existing and Proposed Models)

POC-1

PRE-DEVELOPED RUNOFF CONDITION INPUT FILE
[TITLE]
;;Project Title/Notes
Camino Largo, Vista, CA, Pre-Developed Runoff Condition, POC-1 [OPTIONS]
;;Option Value
FLOW_UNITS CFS
INFILTRATION GREEN_AMPT
FLOW_ROUTING KINWAVE
LINK OFFSETS DEPTH
MIN_SLOPE 0
ALLOW_PONDING NO

SKIP STEADY STATE NO
START_DATE 08/28/1951
START_TIME 05:00:00
REPORT_START_DATE 08/28/1951
REPORT START TIME 05:00:00
END—DATE 05/23/2008
END_TIME 23:00:00
SWEEP START 01/01
SWEEP END 12/31
DRY DAYS 0
REPORT STEP 01:00:00
WET—STEP 00:15:00
DRY STEP 04:00:00
ROUTING STEP 0:01:00
INERTIAL_DAMPING PARTIAL
NORMAL_FLOW_LIMITED BOTH

FORCE MAIN EQUATION H-W
VARIABLE STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
MAX TRIALS 0
HEAD TOLERANCE 0
SYS FLOW TOL 5
LAT_FLOW_TOL 5
MINIMUM STEP 0.5
THREADS 1
48 [EVAPORATION]
;;Data Source Parameters
. .-------------- ----------------
MONTHLY 0.03 0.05 0.08 0.11 0.13 0.15 0.15 0.13 0.11 0.08 0.04 0.02 DRY ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
. .-------------- --------- ------ ------ ----------
OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Impery Width %Slope CurbLen SnowPack . .-------------- ---------------- ---------------- -------- -------- -------- -------- -------- ---------------- DMA-1 OCEANSIDE POC-1 4.952 0 890 7.10 0 [SUBAREAS]
;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted DMA-1 0.012 0.10 0.05 0.1 25 OUTLET [INFILTRATION]
;;Subcatchment Suction Ksat IMD
. .-------------- ---------- ---------- ----------
DMA-1 9 0.025 0.30
[OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To POC-1 0 FREE NO
[TIMESERIES]
;;Name Date Time Value
. .-------------- ---------- ---------- ----------
OCEANSIDE FILE "K:\Library\Stormwater\SWMM\RAIN GAGES\Oceanside Rain Data.dat" [REPORT]
;;Reporting Options
INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL

[TAGS]
[MAP]
DIMENSIONS 191.920 4920.830 1021.827 5718.627
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
. .-------------- ------------------ ------------------ POC-1 757.069 4959.747
[VERTICES]
;;Link X-Coord Y-Coord
. .-------------- ------------------ ------------------ [Polygons]
;;Subcatchment X-Coord Y-Coord
. .-------------- ------------------ ------------------ DMA-1 706.040 5124.523
[SYMBOLS]
;;Gage X-Coord Y-Coord
. .-------------- ------------------ ------------------ OCEANSIDE 757.548 5779.526

POC-1

POST-DEVELOPED RUNOFF CONDITION INPUT FILE
[TITLE]
;;Project Title/Notes
Camino Largo, Vista, CA Post-Developed Mitigated Runoff Condition - POC-1 [OPTIONS]
;;Option Value
FLOW UNITS CFS
INFILTRATION GREEN_AMPT
FLOW ROUTING KINWAVE
LINK OFFSETS DEPTH
MIN SLOPE 0
ALLOW_PONDING NO

SKIP STEADY STATE NO
START DATE 08/28/1951
START TIME 05:00:00
REPORT START DATE 08/28/1951
REPORT_START_TIME 05:00:00
END—DATE 05/23/2008
END_TIME 23:00:00
SWEEP START 01/01
SWEEP END 12/31
DRY DAYS 0
REPORT STEP 01:00:00
WET—STEP 00:15:00
DRY STEP 04:00:00
ROUTING STEP 0:01:00
INERTIAL_DAMPING PARTIAL

NORMAL FLOW LIMITED BOTH
FORCE_MAIN_EQUATION H-W
VARIABLE STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
MAX TRIALS 0
HEAD TOLERANCE 0
SYS_FLOW_TOL 5
LAT FLOW TOL 5
MINIMUM STEP 0.5
THREADS 1

[EVAPORATION]
;;Data Source Parameters
MONTHLY 0.03 0.05 0.08 0.11 0.13 0.15 0.15 0.13 0.11 0.08 0.04 0.02 DRY ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
. .-------------- --------- ------ ------ ----------
OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Impery Width %Slope CurbLen SnowPack . .-------------- ---------------- ---------------- -------- -------- -------- -------- -------- ---------------- DMA-1 OCEANSIDE BMP-1 4.706 58.42 993 8.30 0 BMP-1 OCEANSIDE DIV-1 0.141 0 30 0 0 [SUBAREAS]
;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted . .-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- DMA-1 0.012 0.10 0.05 0.10 25 OUTLET BMP-1 0.012 0.10 0.05 0.10 25 OUTLET [INFILTRATION]
;;Subcatchment Suction Ksat IMD
DMA-1 9 0.01875 0.3
BMP-1 9 0.025 0.3
[LID_CONTROLS]
;;Name Type/Layer Parameters
BMP-1 BC
BMP-1 SURFACE 6.04 0.0 0 0 5 BMP-1 SOIL 18 0.4 0.2 0.1 5 5 1.5 BMP-1 STORAGE 7 0.67 0 0
BMP-1 DRAIN 0.8596 0.5 3 6
[LID USAGE]
;;Subcatchment LID Process Number Area Width InitSat FromImp ToPery RptFile DrainTo
. .-------------- ---------------- ------- ---------- ---------- ---------- ---------- ---------- ---------------------- -- ----------------
BMP-1 BMP-1 1 6141.96 0 0 100 0

[OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To POC-1 0 FREE NO
[DIVIDERS]
;;Name Elevation Diverted Link Type Parameters . .-------------- ---------- ---------------- ---------- ---------- DIV-1 0 BYPASS-1 CUTOFF 0.65321 0 0 0 0 [STORAGE]
;;Name Elev. MaxDepth InitDepth Shape Curve Name/Params N/A Fevap Psi Ksat IMD
. .-------------- -------- ---------- ----------- ---------- ---------------------------- -------- -------- --- STOR-1 0 1.50 0 TABULAR STORAGE-1B 0 0 [CONDUITS]
;;Name From Node To Node Length Roughness InOffset OutOffset InitFlow MaxFlow . .-------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ---------- BYPASS-1 DIV-1 STOR-1 10 0.01 0 0 0 0 DUM 1 DIV-1 POC-1 10 0.01 0 0 0 0 [OUTLETS]
;;Name From Node To Node Offset Type QTable/Qcoeff Qexpon Gated STOR-I-ORIFICE STOR-1 POC-1 0 TABULAR/DEPTH STOR-1BORIFICE NO [XSECTIONS]
;;Link Shape Geoml Geom2 Geom3 Geom4 Barrels Culvert . .-------------- ------------ ---------------- ---------- ---------- ---------- ---------- ---------- BYPASS-1 DUMMY 0 0 0 0 1 DUM 1 DUMMY 0 0 0 0 1
[CURVES]
;;Name Type X-Value Y-Value
. .-------------- ---------- ---------- ----------
STOR-1BORIFICE Rating 0.000 0.000
STOR-1BORIFICE 0.083 1.193
STOR-1BORIFICE 0.167 1.965
STOR-1BORIFICE 0.250 2.459
STOR-1BORIFICE 0.333 2.558
STOR-1BORIFICE 0.417 3.237
STOR-1BORIFICE 0.500 3.859
STOR-1BORIFICE 0.583 4.389

STOR-1BORIFICE 0.667 4.862
STOR-1BORIFICE 0.750 5.292
STOR-1BORIFICE 0.833 5.690
STOR-1BORIFICE 0.917 6.062
STOR-1BORIFICE 1.000 6.413
STOR-1BORIFICE 1.083 6.745
STOR-1BORIFICE 1.167 7.061
STOR-1BORIFICE 1.250 7.364
STOR-1BORIFICE 1.333 9.147
STOR-1BORIFICE 1.417 12.154
STOR-1BORIFICE 1.500 15.956
STOR-1BORIFICE 1.583 20.400
STOR-1BORIFICE 1.667 25.398
STOR-1BORIFICE 1.750 30.890
STORAGE-lB Storage 0.00 6302
STORAGE-lB 0.08 6328
STORAGE-lB 0.17 6354
STORAGE-lB 0.25 6380
STORAGE-1B 0.33 6405
STORAGE-1B 0.42 6431
STORAGE-lB 0.50 6457
STORAGE-1B 0.58 6483
STORAGE-lB 0.67 6509
STORAGE-1B 0.75 6535
STORAGE-lB 0.83 6560
STORAGE-1B 0.92 6586
STORAGE-lB 1.00 6612
STORAGE-1B 1.08 6638
STORAGE-lB 1.17 6664
STORAGE-1B 1.25 6690
STORAGE-lB 1.33 6715
STORAGE-1B 1.42 6741
STORAGE-lB 1.50 6767
[TIMESERIES]
;;Name Date Time Value
. .-------------- ---------- ---------- ----------
OCEANSIDE FILE "K:\Library\Stormwater\SWMM\RAIN GAGES\Oceanside Rain Data.dat" [REPORT]
;;Reporting Options
INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL
[TAGS]
[MAP]
DIMENSIONS 191.920 4920.830 1021.827 5718.627
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
. .-------------- ------------------ ------------------ POC-1 717.654 5272.826
DIV-1 413.901 5274.612
STOR-1 416.581 5123.629
[VERTICES]
;;Link X-Coord Y-Coord
. .-------------- ------------------ ------------------ [Polygons]
;;Subcatchment X-Coord Y-Coord
. .-------------- ------------------ ------------------ DMA-1 159.285 5271.932
BMP-1 277.213 5270.145
[SYMBOLS]
;;Gage X-Coord Y-Coord
. .-------------- ------------------ ------------------ OCEANSIDE 546.123 5415.768

POC-2

PRE-DEVELOPED RUNOFF CONDITION INPUT FILE
[TITLE]
;;Project Title/Notes
Camino Largo, Vista, CA, Pre-Developed Runoff Condition, POC 2 [OPTIONS]
;;Option Value
FLOW UNITS CFS
INFILTRATION GREEN_AMPT
FLOW ROUTING KINWAVE
LINK OFFSETS DEPTH
MIN_SLOPE 0
ALLOW_PONDING NO

SKIP STEADY STATE NO
START_DATE 08/28/1951
START_TIME 05:00:00
REPORT START DATE 08/28/1951
REPORT_START_TIME 05:00:00
END—DATE 05/23/2008
END_TIME 23:00:00
SWEEP START 01/01
SWEEP END 12/31
DRY DAYS 0
REPORT STEP 01:00:00
WET—STEP 00:15:00
DRY STEP 04:00:00
ROUTING STEP 0:01:00
INERTIAL_DAMPING PARTIAL

NORMAL FLOW LIMITED BOTH
FORCE_MAIN_EQUATION H-W
VARIABLE STEP 0.75
LENGTHENING STEP 0

MIN_SURFAREA 0
MAX TRIALS 0
HEAD TOLERANCE 0
SYS_FLOW_TOL 5
LAT FLOW TOL 5
MINIMUM STEP 0.5
THREADS 1
[EVAPORATION]
;;Data Source Parameters
. .-------------- ----------------
MONTHLY 0.03 0.05 0.08 0.11 0.13 0.15 0.15 0.13 0.11 0.08 0.04 0.02 DRY ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
. .-------------- --------- ------ ------ ----------
OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Impery Width %Slope CurbLen SnowPack DMA-1 OCEANSIDE POC-1 3.121 0 507 10.10 0 BYPASS2 OCEANSIDE POC-1 1.031 0 785 11.2 0 [SUBAREAS]
;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted DMA-1 0.012 0.10 0.05 0.1 25 OUTLET BYPASS2 0.012 0.10 0.05 0.10 25 OUTLET [INFILTRATION]
;;Subcatchment Suction Ksat IMD
. .-------------- ---------- ---------- ----------
DMA-1 9 0.025 0.30
BYPASS2 9 0.025 0.30
[OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To . .-------------- ---------- ---------- ---------------- -------- ---------------- POC-1 0 FREE NO
[TIMESERIES]
;;Name Date Time Value

OCEANSIDE FILE "K:\Library\Stormwater\SWMM\RAIN GAGES\Oceanside Rain Data.dat" [REPORT]
;;Reporting Options
INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL
[TAGS]
[MAP]
DIMENSIONS 191.920 4920.830 1021.827 5718.627
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
. .-------------- ------------------ ------------------ POC-1 757.069 4959.747
[VERTICES]
;;Link X-Coord Y-Coord
[Polygons]
;;Subcatchment X-Coord Y-Coord
DMA-1 706.040 5124.523
BYPASS2 804.759 5127.873
[SYMBOLS]
;;Gage X-Coord Y-Coord
. .-------------- ------------------ ------------------ OCEANSIDE 757.548 5779.526

POC-2

POST-DEVELOPED RUNOFF CONDITION INPUT FILE
[TITLE]
;;Project Title/Notes
Camino Largo, Vista, CA Post-Developed Mitigated Runoff Condition - POC 2 [OPTIONS]
;;Option Value
FLOW UNITS CFS
INFILTRATION GREEN_AMPT
FLOW ROUTING KINWAVE
LINK OFFSETS DEPTH
MIN_SLOPE 0
ALLOW_PONDING NO

NORMAL FLOW LIMITED BOTH
FORCE_MAIN_EQUATION H-W
VARIABLE STEP 0.75
LENGTHENING STEP 0

MIN_SURFAREA 0
MAX TRIALS 0
HEAD TOLERANCE 0
SYS_FLOW_TOL 5
LAT FLOW TOL 5
MINIMUM STEP 0.5
THREADS 1
[EVAPORATION]
;;Data Source Parameters
. .-------------- ----------------
MONTHLY 0.03 0.05 0.08 0.11 0.13 0.15 0.15 0.13 0.11 0.08 0.04 0.02 DRY ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
. .-------------- --------- ------ ------ ----------
OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Impery Width %Slope CurbLen SnowPack DMA-2 OCEANSIDE BMP-2 3.146 57.73 818 4.50 0 BMP-2 OCEANSIDE DIV-2 0.213 0 20 0 0 BYPASS2 OCEANSIDE POC-1 1.699 0 785 11.20 0 [SUBAREAS]
;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted . .-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- DMA-2 0.012 0.10 0.05 0.10 25 OUTLET BMP-2 0.012 0.10 0.05 0.10 25 OUTLET BYPASS2 0.012 0.10 0.05 0.10 25 OUTLET [INFILTRATION]
;;Subcatchment Suction Ksat IMD
. .-------------- ---------- ---------- ----------
DMA-2 9 0.01875 0.3
BMP-2 9 0.025 0.3
BYPASS2 9 0.025 0.3
[LID_CONTROLS]
;;Name Type/Layer Parameters
. .-------------- ---------- ----------
BMP-2 BC
BMP-2 SURFACE 6.08 0.0 0.1 0 5

BMP-2 SOIL 18 0.4 0.2 0.1 5 5 1.5 BMP-2 STORAGE 7 0.67 0 0
BMP-2 DRAIN 0.3203 0.5 3 6
[LID USAGE]
;;Subcatchment LID Process Number Area Width InitSat FromImp ToPery RptFile DrainTo
-- ----------------
BMP-2 BMP-2 1 8319.96 0 0 100 0 [OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To . .-------------- ---------- ---------- ---------------- -------- ---------------- POC-1 0 FREE NO
[DIVIDERS]
;;Name Elevation Diverted Link Type Parameters . .-------------- ---------- ---------------- ---------- ---------- DIV-2 0 BYPASS-2 CUTOFF 0.37058 0 0 0 0 [STORAGE]
;;Name Elev. MaxDepth InitDepth Shape Curve Name/Params N/A Fevap Psi Ksat IMD
. .-------------- -------- ---------- ----------- ---------- ---------------------------- -------- -------- --- STOR-2 0 1.50 0 TABULAR STORAGE-1B 0 0 [CONDUITS]
;;Name From Node To Node Length Roughness InOffset OutOffset InitFlow MaxFlow . .-------------- ---------------- ---------------- ---------- ---------- ---------- ---------- ---------- ---------- BYPASS-2 DIV-2 STOR-2 10 0.01 0 0 0 0 DUM 2 DIV-2 POC-1 10 0.01 0 0 0 0 [OUTLETS]
;;Name From Node To Node Offset Type QTable/Qcoeff Qexpon Gated . .-------------- ---------------- ---------------- ---------- --------------- ---------------- ---------- -------- STOR-2-ORIFICE STOR-2 POC-1 0 TABULAR/DEPTH STOR-1BORIFICE NO [XSECTIONS]
;;Link Shape Geom1 Geom2 Geom3 Geom4 Barrels Culvert . .-------------- ------------ ---------------- ---------- ---------- ---------- ---------- ---------- BYPASS-2 DUMMY 0 0 0 0 1 DUM 2 DUMMY 0 0 0 0 1

[CURVES]
;;Name Type X-Value Y-Value
STOR-1BORIFICE Rating 0.000 0.000
STOR-1BORIFICE 0.083 0.674
STOR-1BORIFICE 0.167 1.038
STOR-1BORIFICE 0.250 1.287
STOR-1BORIFICE 0.333 1.720
STOR-1BORIFICE 0.417 2.001
STOR-1BORIFICE 0.500 2.273
STOR-1BORIFICE 0.583 2.516
STOR-1BORIFICE 0.667 2.737
STOR-1BORIFICE 0.750 2.942
STOR-1BORIFICE 0.833 3.134
STOR-1BORIFICE 0.917 3.314
STOR-1BORIFICE 1.000 3.485
STOR-1BORIFICE 1.083 4.530
STOR-1BORIFICE 1.167 6.300
STOR-1BORIFICE 1.250 8.538
STOR-1BORIFICE 1.333 11.156
STOR-1BORIFICE 1.417 14.102
STOR-1BORIFICE 1.500 17.339
STOR-1BORIFICE 1.583 20.843
STOR-1BORIFICE 1.667 24.594
STOR-1BORIFICE 1.750 28.575
STORAGE-1B Storage 0.00 9515
STORAGE-lB 0.08 9554
STORAGE-1B 0.17 9593
STORAGE-lB 0.25 9632
STORAGE-1B 0.33 9672
STORAGE-lB 0.42 9711
STORAGE-1B 0.50 9750
STORAGE-lB 0.58 9789
STORAGE-1B 0.67 9829
STORAGE-lB 0.75 9868
STORAGE-1B 0.83 9907
STORAGE-lB 0.92 9946
STORAGE-1B 1.00 9986
STORAGE-lB 1.08 10025
STORAGE-1B 1.17 10064
STORAGE-lB 1.25 10103
STORAGE-1B 1.33 10143
STORAGE-lB 1.42 10182
STORAGE-1B 1.50 10221

[TIMESERIES]
;;Name Date Time Value
. .-------------- ---------- ---------- ----------
OCEANSIDE FILE "K:\Library\Stormwater\SWMM\RAIN GAGES\Oceanside Rain Data.dat" [REPORT]
;;Reporting Options
INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL
[TAGS]
[MAP]
DIMENSIONS 191.920 4920.830 1021.827 5718.627
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
. .-------------- ------------------ ------------------ POC-1 717.654 5272.826
DIV-2 413.901 5272.826
STOR-2 419.262 5124.523
[VERTICES]
;;Link X-Coord Y-Coord
[Polygons]
;;Subcatchment X-Coord Y-Coord
. .-------------- ------------------ ------------------ DMA-2 159.285 5271.932
BMP-2 278.999 5270.145
BYPASS2 722.121 5432.742
[SYMBOLS]
;;Gage X-Coord Y-Coord
. .-------------- ------------------ ------------------ OCEANSIDE 546.123 5415.768

ATTACHMENT 7
SWMM Screens and Explanation of Significant Variables
65 EPA SWMM Figures and Explanations
Per the attached, the reader can see the screens associated with the EPA-SWMM Model in both pre- development and post-development conditions. Each portion, i.e., sub-catchments, storage units, weirs and orifices as a discharge, and outfalls (point of compliance), are also shown.

Variables for modeling are associated with typical recommended values by the EPA-SWMM model and the Model BMP Design Manual San Diego Region.

Soil characteristics of the existing soils were determined from the site specific NRCS Web Soil Survey.

Some values incorporated within the SWMM model have been determined from the professional experience of BHA using conservative assumptions that have a tendency to increase the size of the needed BMP and also generate a long-term runoff as a percentage of rainfall similar to those measured in gage stations in Southern California by the USGS.

PRE-DEVELOPED CONDITION (POC-1)
DMA,-1
Q
PO -1

POST-DEVELOPED CONDITION (POC-1)

OCEANSIDE
El
DMA-1 BMP-1 DIV-1 DUM 1 POC-1
■---------------------■-------------------- -
STOP-1-ORIFICE
BYPASS-1
STOR-1
wir
68 PRE-DEVELOPED CONDITION (POC-2)
DMA-1 BYPASS2
POD-1
i

POST-DEVELOPED CONDITION (POC-2)
B Y PAS S2

OCEANSIDE
0 DMA-2 BMP-2 DIV-2 DUM 2 POC-1
STOP-2-OPIFICE
BYPASS-2
STOR-2
Ilit-
70 Explanation of Selected Variables
• Sub Catchment Areas: Please refer to the attached diagram that indicates the DMA and biofiltration BMP sub-areas modeled within the project site at both the pre and post- developed conditions draining to the project's POCs.

Parameters for the pre-developed model include soils Type C and D as determined from the NRCS Web Soils Survey and ArcGIS BMP Sizing Calculator(see Attachment 8). For the purpose of this report, the entire project site will be modeled with Type D soils. Suction head, conductivity and initial deficit correspond to average values expected for this soil type, according to the BMP Design Manual (BMPDM).
• Selection of a Kinematic Approach: As the continuous model is based on hourly rainfall, and the time of concentration for the pre-development and post-development conditions is significantly smaller than 60 minutes, precise routing of the flows through the impervious surfaces, the underdrain pipe system, and the discharge pipe was considered unnecessary.

The truncation error of the precipitation into hourly steps is much more significant that the precious routing in a system where the time of concentration is much smaller than 1 hour. • Sub Catchment BMP: The subcatchment BMP is assigned the area of biofiltration, which is equal to the area of amended soil. At least five (5) decimal places were given regarding the area of the biofiltration to insure that the area used by the program for the LID subroutine corresponds exactly with the actual biofiltration area.

LID Control Editor: Explanation of Significant Variables • Storage Depth: The storage depth variable within the SWMM model is representative of the storage volume provided beneath the lowest surface outlet within the biofiltration basin.

This is the volume that can only discharge from the facility via the LID portion of the basin.

In those cases where the surface storage has a variable area that is also different to the area of the gravel and amended soil, the SWMM model needs to be calibrated as the LID module will use the storage depth multiplied by the BMP area as the amount of volume stored at the surface.

Let ABMP be the area of the BMP (area of amended soil and area of gravel). The proper value of the storage depth SD to be included in the LID module can be calculated by using geometric properties of the surface volume. Let Ao be the surface area at the bottom of the surface

pond, and let A; be the surface area at the elevation of the invert of the first row of orifices (or at the invert of the riser if not surface orifices are included). Finally, let h; be the difference in elevation between Ao and A;. By volumetric definition:

ABMP * SD — (AO Ai)hi (1)
Equation (1) allows the determination of SD to be included as Storage Depth in the LID module.
• Porosity: A porosity value of 0.4 has been selected for the model. The amended soil is to be highly sandy in content in order to have a saturated hydraulic conductivity of approximately 5 in/hr.

BHA considers such a value to be slightly high; however, in order to comply with the BMPDM, the value recommended by the Copermittees for the porosity of amended soil is 0.4, per Appendix G of the BMPDM. Such porosity is equal to the porosity of the gravel per the same manual.
• Porosity:The ratio of the void volume divided by the soil volume is directly related to porosity.

Note, by definition, Porosity = Void Ratio _ (1 + Void Ratio). As the underdrain layer is composed of gravel, a porosity value of 0.4 has been selected (also per Appendix G of the BMPDM), which results in a void ratio of 0.4/(1+0.4) = 0.67 for the gravel detention layer. • Conductivity: Due to the preliminary nature of this study, infiltration may not be a viable addition to the LID design. Even when soil types C and D are present, which generally have low infiltration rates, the possibility that a very low infiltration rate could be determined at design level must be considered. The range of potential infiltration rates to be studied when a site-specific geotechnical investigation has not been completed is shown in Table G.1-5 of the BMP Design Manual. Based on the infiltration rates shown, a conservative low infiltration rate of 0 inches per hour was selected for soil Type D. Therefore, as the BMPs are designed without infiltration, the conductivity value was set to 0 to represent zero infiltration. • Clogging factor: A clogging factor was not used (0 indicates that there is not clogging assumed within the model). The reason for this is related to the fairness of a comparison with the SDHM model and the HMP sizing tables: a clogging factor was not considered. • Drain (Flow) coefficient: The flow coefficient in the SWMM Model is the coefficient needed to transform the orifice equation into a general power law equation of the form:

q = C(H — HD)n (2)
where,
q is the peak flow in in/hr;
n is exponent (typically 0.5 for orifice equation);
HD is the elevation of the centroid of the orifice in inches (assumed equal to the invert of the orifice for small orifices and in our design equal to 0); and H is the depth of the water in inches.

The general orifice equation can be expressed as:
_ CTr DZT2g
(H—Hp) (3)
Q 4 9 144 12
where,
Q is the peak flow in cfs;
D is the underdrain orifice diameter in inches;
cg is the typical discharge coefficient for orifices(0.60-0.65 for thin walls and 0.75-0.80 for thick walls);
g is the gravitational constant (32.2 ft/S2); and
H and HD are defined above are also used in inches in Equation (3).

It is clear that:
_ In ABMp C S 4
q hr 12*3600 — Q( ) ( )
The flow coefficient used in the SWMM Model characterizes the rate of discharge to the outlet as a function of the height of water stored in the biofiltration cell. The flow coefficient, as presented in the BMPDM, can be determined by the following equation:

C = Cy �ADs) (nag) 6 (5)
lid
where,
cg is the orifice discharge coefficient (0.60-0.65 for thin walls and 0.75-0.80 for thick walls);
Ai;d is the cumulative footprint area (ft2) of all LID controls; D is the underdrain orifice diameter in inches; and
g is the gravitational constant (32.2 ft/S2);

• Cut-Off Flow: The cut-off flow represents the maximum flow rate leaving the "low flow" outlet. The low-flow restrictor is typically more restrictive (i.e. smaller flow rate) than the percolation rate through the engineered soil; therefore, the orifice equation is used to calculate the cutoff flow when H is maximum.

ATTACHMENT 8
Geotechnical Documentation
(See Attachment 5 in SWAMP)

ATTACHMENT 9
Summary Files from the SWMM Model

PRE-DEVELOPED RUNOFF CONDITION (POC-1) OUTPUT FILE EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) -------------------------------------------------------------- Camino Largo, Vista, CA, Pre-Developed Runoff Condition, POC-1 ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step.
********************************************************* ****************
Analysis Options
****************
Flow Units . . . . . . . . . . . . . . . CFS
Process Models:

Rainfall/Runoff . . . . . . . . YES
RDII . . . . . . . . . . . . . . . . . . . NO
Snowmelt . . . . . . . . . . . . . . . NO
Groundwater . . . . . . . . . . . . NO
Flow Routing . . . . . . . . . . . NO
Water Quality . . . . . . . . . . NO
Infiltration Method . . . . . . GREEN_AMPT
Starting Date . . . . . . . . . . . . 08/28/1951 05:00:00 Ending Date . . . . . . . . . . . . . . 05/23/2008 23:00:00 Antecedent Dry Days . . . . . . 0.0
Report Time Step . . . . . . . . . 01:00:00
Wet Time Step . . . . . . . . . . . . 00:15:00
Dry Time Step . . . . . . . . . . . . 04:00:00
************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
**************************
Total Precipitation . . . . . . 278.595 675.110
Evaporation Loss . . . . . . . . . 6.647 16.107 Infiltration Loss . . . . . . . . 213.620 517.658 Surface Runoff . . . . . . . . . . . 62.281 150.923 Final Storage . . . . . . . . . . . . 0.000 0.000 Continuity Error (o) . . . . . -1.419
77 ************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
**************************
Dry Weather Inflow . . . . . . . 0.000 0.000 Wet Weather Inflow . . . . . . . 62.281 20.295 Groundwater Inflow . . . . . . . 0.000 0.000 RDII Inflow . . . . . . . . . . . . . . 0.000 0.000 External Inflow . . . . . . . . . . 0.000 0.000 External Outflow . . . . . . . . . 62.281 20.295 Flooding Loss . . . . . . . . . . . . 0.000 0.000 Evaporation Loss . . . . . . . . . 0.000 0.000 Exfiltration Loss . . . . . . . . 0.000 0.000 Initial Stored Volume . . . . 0.000 0.000
Final Stored Volume . . . . . . 0.000 0.000 Continuity Error (%) . . . . . 0.000
***************************
Subcatchment Runoff Summary
***************************
-------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS -------------------------------------------------------------------------------------------------------- DMA-1 675.11 0.00 16.11 517.66 150.92 20.29 5.56 0.224 Analysis begun on: Sat Aug 14 14:13:46 2021
Analysis ended on: Sat Aug 14 14:14:22 2021
Total elapsed time: 00:00:36

POST-DEVELOPED RUNOFF CONDITION (POC-1) OUTPUT FILE
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) -------------------------------------------------------------- Camino Largo, Vista, CA Post-Developed Mitigated Runoff Condition - POC-1 WARNING 04: minimum elevation drop used for Conduit BYPASS-1 WARNING 04: minimum elevation drop used for Conduit DUM 1 ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step.
********************************************************* ****************
Analysis Options
****************
Flow Units . . . . . . . . . . . . . . . CFS
Process Models:

Rainfall/Runoff . . . . . . . . YES
RDII . . . . . . . . . . . . . . . . . . . NO
Snowmelt . . . . . . . . . . . . . . . NO
Groundwater . . . . . . . . . . . . NO
Flow Routing . . . . . . . . . . . YES
Ponding Allowed . . . . . . . . NO
Water Quality . . . . . . . . . . NO
Infiltration Method . . . . . . GREEN_AMPT
Flow Routing Method . . . . . . KINWAVE
Starting Date . . . . . . . . . . . . 08/28/1951 05:00:00 Ending Date . . . . . . . . . . . . . . 05/23/2008 23:00:00 Antecedent Dry Days . . . . . . 0.0
Report Time Step . . . . . . . . . 01:00:00
Wet Time Step . . . . . . . . . . . . 00:15:00
Dry Time Step . . . . . . . . . . . . 04:00:00
Routing Time Step . . . . . . . . 60.00 sec
************************** Volume Depth

Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Initial LID Storage . . . . . . 0.021 0.052 Total Precipitation . . . . . . 272.688 675.110
Evaporation Loss . . . . . . . . . 30.080 74.470 Infiltration Loss . . . . . . . . 77.561 192.022 Surface Runoff . . . . . . . . . . . 13.864 34.325 LID Drainage . . . . . . . . . . . . . 154.588 382.722 Final Storage . . . . . . . . . . . . 0.040 0.100 Continuity Error (%) . . . . . -1.255
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow . . . . . . . 0.000 0.000 Wet Weather Inflow . . . . . . . 168.453 54.893 Groundwater Inflow . . . . . . . 0.000 0.000 RDII Inflow . . . . . . . . . . . . . . 0.000 0.000 External Inflow . . . . . . . . . . 0.000 0.000 External Outflow . . . . . . . . . 168.461 54.895 Flooding Loss . . . . . . . . . . . . 0.000 0.000 Evaporation Loss . . . . . . . . . 0.000 0.000 Exfiltration Loss . . . . . . . . 0.000 0.000 Initial Stored Volume . . . . 0.000 0.000
Final Stored Volume . . . . . . 0.000 0.000 Continuity Error (%) . . . . . -0.005
********************************
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
Routing Time Step Summary
*************************
Minimum Time Step 60.00 sec
Average Time Step 60.00 sec
Maximum Time Step 60.00 sec
Percent in Steady State 0.00
Average Iterations per Step 1.00
Percent Not Converging 0.00

***************************
Subcatchment Runoff Summary
***************************
-------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS -------------------------------------------------------------------------------------------------------- DMA-1 675.11 0.00 53.04 197.78 433.01 55.33 5.55 0.641 BMP-1 675.11 14452.06 789.58 0.00 14336.36 54.89 5.72 0.948 ***********************
LID Performance Summary
***********************
-------------------------------------------------------------------------------------------------------------------- Total Evap Infil Surface Drain Initial Final Continuity Inflow Loss Loss Outflow Outflow Storage Storage Error Subcatchment LID Control in in in in in in in o -------------------------------------------------------------------------------------------------------------------- BMP-1 BMP-1 15127.17 789.61 0.00 1179.99 13156.89 1.80 2.61 -0.00 Node Depth Summary
--------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth
Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- POC-1 OUTFALL 0.00 0.00 0.00 0 00:00 0.00
DIV-1 DIVIDER 0.00 0.00 0.00 0 00:00 0.00
STOR-1 STORAGE 0.00 0.66 0.66 18857 12:17 0.61 *******************
Node Inflow Summary
*******************
------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow

Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent ------------------------------------------------------------------------------------------------- POC-1 OUTFALL 0.00 5.47 18857 12:17 0 54.9 0.000 DIV-1 DIVIDER 5.72 5.72 18857 12:01 54.9 54.9 0.000 STOR-1 STORAGE 0.00 5.07 18857 12:01 0 4.17 -0.060 Node Flooding Summary
No nodes were flooded.
**********************
Storage Volume Summary
**********************
-------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- STOR-1 0.001 0 0 0 4.226 43 18857 12:16 4.82 ***********************
Outfall Loading Summary
***********************
----------------------------------------------------------- Flow Avg Max Total
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
----------------------------------------------------------- POC-1 2.11 0.19 5.47 54.891
----------------------------------------------------------- System 2.11 0.19 5.47 54.891
Link Flow Summary

----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/
IFlowl Occurrence IVelocl Full Full
Link Type CFS days hr:min ft/sec Flow Depth ----------------------------------------------------------------------------- BYPASS-1 DUMMY 5.07 18857 12:01
DUM_1 DUMMY 0.65 141 06:38
STOR-I-ORIFICE DUMMY 4.82 18857 12:17
Conduit Surcharge Summary
No conduits were surcharged.

Analysis begun on: Fri Dec 03 13:51:33 2021
Analysis ended on: Fri Dec 03 13:52:29 2021
Total elapsed time: 00:00:56

PRE-DEVELOPED RUNOFF CONDITION (POC-2) OUTPUT FILE [TITLE]
;;Project Title/Notes
Camino Largo, Vista, CA, Pre-Developed Runoff Condition, POC 2 [OPTIONS]
;;Option Value
FLOW_UNITS CFS
INFILTRATION GREEN_AMPT
FLOW_ROUTING KINWAVE
LINK OFFSETS DEPTH
MIN_SLOPE 0
ALLOW_PONDING NO

SKIP STEADY STATE NO
START_DATE 08/28/1951
START_TIME 05:00:00
REPORT_START_DATE 08/28/1951
REPORT START TIME 05:00:00
END_DATE 05/23/2008
END_TIME 23:00:00
SWEEP START 01/01
SWEEP END 12/31
DRY DAYS 0
REPORT STEP 01:00:00
WET—STEP 00:15:00
DRY STEP 04:00:00
ROUTING STEP 0:01:00
INERTIAL_DAMPING PARTIAL
NORMAL_FLOW_LIMITED BOTH

FORCE MAIN EQUATION H-W
VARIABLE_STEP 0.75
LENGTHENING_STEP 0
MIN_SURFAREA 0
MAX TRIALS 0
HEAD TOLERANCE 0
SYS FLOW TOL 5
LAT FLOW TOL 5
MINIMUM STEP 0.5
THREADS 1
[EVAPORATION]
;;Data Source Parameters
84 MONTHLY 0.03 0.05 0.08 0.11 0.13 0.15 0.15 0.13 0.11 0.08 0.04 0.02 DRY ONLY NO
[RAINGAGES]
;;Name Format Interval SCF Source
OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE
[SUBCATCHMENTS]
;;Name Rain Gage Outlet Area %Impery Width %Slope CurbLen SnowPack . .-------------- ---------------- ---------------- -------- -------- -------- -------- -------- ---------------- DMA-1 OCEANSIDE POC-1 3.121 0 507 10.10 0 BYPASS2 OCEANSIDE POC-1 1.031 0 785 11.2 0 [SUBAREAS]
;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted . .-------------- ---------- ---------- ---------- ---------- ---------- ---------- ---------- DMA-1 0.012 0.10 0.05 0.1 25 OUTLET BYPASS2 0.012 0.10 0.05 0.10 25 OUTLET [INFILTRATION]
;;Subcatchment Suction Ksat IMD
DMA-1 9 0.025 0.30
BYPASS2 9 0.025 0.30
[OUTFALLS]
;;Name Elevation Type Stage Data Gated Route To POC-1 0 FREE NO
[TIMESERIES]
;;Name Date Time Value
. .-------------- ---------- ---------- ----------
OCEANSIDE FILE "K:\Library\Stormwater\SWMM\RAIN GAGES\Oceanside Rain Data.dat" [REPORT]
;;Reporting Options
INPUT NO

CONTROLS NO

SUBCATCHMENTS ALL

NODES ALL

LINKS ALL

[TAGS]
[MAP]
DIMENSIONS 191.920 4920.830 1021.827 5718.627
Units None
[COORDINATES]
;;Node X-Coord Y-Coord
. .-------------- ------------------ ------------------ POC-1 757.069 4959.747
[VERTICES]
;;Link X-Coord Y-Coord
. .-------------- ------------------ ------------------ [Polygons]
;;Subcatchment X-Coord Y-Coord
. .-------------- ------------------ ------------------ DMA-1 706.040 5124.523
BYPASS2 804.759 5127.873
[SYMBOLS]
;;Gage X-Coord Y-Coord
OCEANSIDE 757.548 5779.526

POST-DEVELOPED RUNOFF CONDITION (POC-2) OUTPUT FILE
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.1 (Build 5.1.012) -------------------------------------------------------------- Camino Largo, Vista, CA Post-Developed Mitigated Runoff Condition - POC 2 WARNING 04: minimum elevation drop used for Conduit BYPASS-2 WARNING 04: minimum elevation drop used for Conduit DUM 2 NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step.
********************************************************* ****************
Analysis Options
****************
Flow Units . . . . . . . . . . . . . . . CFS
Process Models:

************************** Volume Depth
Runoff Quantity Continuity acre-feet inches
************************** --------- -------
Initial LID Storage . . . . . . 0.029 0.068 Total Precipitation . . . . . . 284.559 675.110
Evaporation Loss . . . . . . . . . 26.243 62.262 Infiltration Loss . . . . . . . . 160.973 381.906 Surface Runoff . . . . . . . . . . . 22.730 53.926 LID Drainage . . . . . . . . . . . . . 3.397 8.058 Final Storage . . . . . . . . . . . . 74.291 176.254 Continuity Error (o) . . . . . -1.070
************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow . . . . . . . 0.000 0.000 Wet Weather Inflow . . . . . . . 26.126 8.514 Groundwater Inflow . . . . . . . 0.000 0.000 RDII Inflow . . . . . . . . . . . . . . 0.000 0.000 External Inflow . . . . . . . . . . 0.000 0.000 External Outflow . . . . . . . . . 26.126 8.514 Flooding Loss . . . . . . . . . . . . 0.000 0.000 Evaporation Loss . . . . . . . . . 0.000 0.000 Exfiltration Loss . . . . . . . . 0.000 0.000 Initial Stored Volume . . . . 0.000 0.000
Final Stored Volume . . . . . . 0.000 0.000 Continuity Error (%) . . . . . 0.000
********************************
Highest Flow Instability Indexes
********************************
All links are stable.
*************************
Routing Time Step Summary
*************************
Minimum Time Step 60.00 sec
Average Time Step 60.00 sec
Maximum Time Step 60.00 sec
Percent in Steady State 0.00
Average Iterations per Step 1.00

Percent Not Converging 0.00
***************************
Subcatchment Runoff Summary
***************************
-------------------------------------------------------------------------------------------------------- Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 10^6 gal CFS -------------------------------------------------------------------------------------------------------- DMA-2 675.11 0.00 52.68 201.79 429.22 36.67 3.71 0.636 BMP-2 675.11 6339.49 606.44 2033.37 191.36 1.11 0.10 0.027 BYPASS2 675.11 0.00 11.78 508.39 160.54 7.41 1.91 0.238 LID Performance Summary
-------------------------------------------------------------------------------------------------------------------- Total Evap Infil Surface Drain Initial Final Continuity Inflow Loss Loss Outflow Outflow Storage Storage Error Subcatchment LID Control in in in in in in in % -------------------------------------------------------------------------------------------------------------------- BMP-2 BMP-2 675.11 461.60 0.00 0.00 213.41 1.80 1.89 0.00 ******************
Node Depth Summary
******************
--------------------------------------------------------------------------------- Average Maximum Maximum Time of Max Reported Depth Depth HGL Occurrence Max Depth
Node Type Feet Feet Feet days hr:min Feet --------------------------------------------------------------------------------- POC-1 OUTFALL 0.00 0.00 0.00 0 00:00 0.00
DIV-2 DIVIDER 0.00 0.00 0.00 0 00:00 0.00
STOR-2 STORAGE 0.00 0.00 0.00 0 00:00 0.00 Node Inflow Summary

------------------------------------------------------------------------------------------------- Maximum Maximum Lateral Total Flow
Lateral Total Time of Max Inflow Inflow Balance Inflow Inflow Occurrence Volume Volume Error Node Type CFS CFS days hr:min 10^6 gal 10^6 gal Percent ------------------------------------------------------------------------------------------------- POC-1 OUTFALL 1.91 1.91 18857 12:01 7.41 8.51 0.000 DIV-2 DIVIDER 0.10 0.10 10002 09:31 1.11 1.11 0.000 STOR-2 STORAGE 0.00 0.00 0 00:00 0 0 0.000 gal Node Flooding Summary
*********************
No nodes were flooded.

Storage Volume Summary
-------------------------------------------------------------------------------------------------- Average Avg Evap Exfil Maximum Max Time of Max Maximum Volume Pcnt Pcnt Pcnt Volume Pcnt Occurrence Outflow Storage Unit 1000 ft3 Full Loss Loss 1000 ft3 Full days hr:min CFS -------------------------------------------------------------------------------------------------- STOR-2 0.000 0 0 0 0.000 0 0 00:00 0.00 Outfall Loading Summary
----------------------------------------------------------- Flow Avg Max Total
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
----------------------------------------------------------- POC-1 0.66 0.10 1.91 8.513
----------------------------------------------------------- System 0.66 0.10 1.91 8.513

********************
Link Flow Summary
********************
----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/
IFlowl Occurrence IVelocl Full Full
Link Type CFS days hr:min ft/sec Flow Depth ----------------------------------------------------------------------------- BYPASS-2 DUMMY 0.00 0 00:00
DUM_2 DUMMY 0.10 10002 09:31
STOR-2-ORIFICE DUMMY 0.00 0 00:00
*************************
Conduit Surcharge Summary
*************************
No conduits were surcharged.

Analysis begun on: Fri Dec 03 17:24:45 2021
Analysis ended on: Fri Dec 03 17:25:39 2021
Total elapsed time: 00:00:54

ATTACHMENT 10
Drawdown Calculations
92 Drawdown Calculations
Note: Drawdown calculations are from invert of lowest surface discharge opening in riser structure to the surface bottom of the basin. Therefore, discharge occurs only through the underdrain orifice.

Drawdown Calculations for BMP 1

ORIFICE FLOW
Surface Ponding Depth: PD 6 in
Ponding Depth Surface Area: APp 6147 ft2
Surface Ponding Volume: VPo 2408 ft3
Low Flow Orifice Diameter: D 4.00 in
Flow Rate (volumetric): Q 0.371 ft3/s
Drawdown Time: 1.81 hrs
INFILTRATION CONTROLS✓
Surface Ponding Depth: PD 6 in
Ponding Depth Surface Area: APo 6147 ft2
Surface Ponding Volume: VPp 2408 ft3
INFILTRATION RATE 1 5.00 in/hr
Flow Rate (volumetric): Q 0.711 ft3/s
Drawdown Time: 0.94 hrs

Drawdown Calculations for BMP 2

ORIFICE FLOW
Surface Ponding Depth: PD 6 in
Ponding Depth Surface Area: APo 9279 ft2
Surface Ponding Volume: VPp 2408 ft3
Low Flow Orifice Diameter: D 3.00 in
Flow Rate (volumetric): Q 0.371 ft3/s
Drawdown Time: 1.81 hrs
INFILTRATION CONTROLS✓
Surface Ponding Depth: PD 6 in
Ponding Depth Surface Area: APp 9279 ft2
Surface Ponding Volume: VPo 2408 ft3
INFILTRATION RATE 1 5.00 in/hr
Flow Rate (volumetric): Q 1.074 ft3/s
Drawdown Time: 0.62 hrs

ATTACHMENT 3 - BMP MAINTENANCE INFORMATION
Each of the attachments indicated below should be considered for inclusion with the SWAMP. Use this checklist to indicate which attachments are included behind this coversheet.

Attachment Contents Checklist
Sequence
Attachment 3A Structural BMP Operations ❑X Included and Maintenance Plan
See Structural BMP Maintenance Information
Checklist on the back of this Attachment cover sheet.

Attachment 3B Draft Maintenance 0 Included
Agreement ❑ Not Applicable

Page 55 of 73 ends

Vista City CouncilAugust 23, 2022

Vista City Council
August 23, 2022