> Appendix-N-SWQMP — San Marcos City Council, June 24, 2025

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
City of San Marcos

PRIORITY DEVELOPMENT PROJECT (PDP)

STORM WATER QUALITY MANAGEMENT PLAN (SWQMP)
FOR
Armorlite Lofts
Permit SP23-0001
Armorlite Drive
San Marcos, California 92069
ASSESSOR'S PARCEL NUMBER(S):
219-162-62-00
ENGINEER OF WORK:
17031 Treena Street, San Diego CA 92131 • T 858.751.0633 • www.latitude33.com ___________________________________________________________________________________ Gio Posillico R.C.E. NO. 66332 EXP. 06-30-25

PREPARED FOR:

Las Posas Ventures, LLC
Att: Dan Tate, [email protected]
705 B Street, Suite 3010
San Diego, CA 92101
619-981-0579
PDP SWQMP PREPARED BY:

Latitude 33 Planning & Engineering
17031 Treena Street
San Diego, CA 92131
858-751-0633
DATE OF SWQMP:

June 6, 2023
PLANS PREPARED BY:

Latitude 33 Planning & Engineering
17031 Treena Street
San Diego, CA 92131
858-751-0633

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
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City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

TABLE OF CONTENTS
Acronym Sheet
PDP SWQMP Preparer's Certification Page
PDP SWQMP Project Owner's Certification Page
Submittal Record
Project Vicinity Map
FORM I-1 Applicability of Storm Water BMP Requirements
FORM I-2 Project Type Determination Checklist (Standard Project or PDP) FORM I-3B Site Information Checklist for PDPs
FORM I-4 Source Control BMP Checklist for All Development Projects FORM I-5 Site Design BMP Checklist for All Development Projects FORM I-6 Summary of PDP Structural BMPs
Attachment 1: Backup for PDP Pollutant Control BMPs
Attachment 1a: DMA Exhibit
Attachment 1b: Tabular Summary of DMAs and Design Capture Volume Calculations Attachment 1c: Harvest and Use Feasibility Screening (when applicable) Attachment 1d: Categorization of Infiltration Feasibility Condition (when applicable) Attachment 1e: Pollutant Control BMP Design Worksheets / Calculations Attachment 2: Backup for PDP Hydromodification Control Measures Attachment 2a: Hydromodification Management Exhibit
Attachment 2b: Management of Critical Coarse Sediment Yield Areas Attachment 2c: Geomorphic Assessment of Receiving Channels Attachment 2d: Flow Control Facility Design
Attachment 3: Structural BMP Maintenance Plan
Attachment 3a: B Structural BMP Maintenance Thresholds and Actions Attachment 3b: Draft Maintenance Agreement (when applicable) Attachment 4: Copy of Plan Sheets Showing Permanent Storm Water BMPs

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

ACRONYMS
APN Assessor's Parcel Number
BMP Best Management Practice
HMP Hydromodification Management Plan
HSG Hydrologic Soil Group
MS4 Municipal Separate Storm Sewer System
N/A Not Applicable
NRCS Natural Resources Conservation Service
PDP Priority Development Project
PE Professional Engineer
SC Source Control
SD Site Design
SDRWQCB San Diego Regional Water Quality Control Board
SIC Standard Industrial Classification
SWQMP Storm Water Quality Management Plan

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

PDP SWQMP PREPARER'S CERTIFICATION PAGE
Project Name: Armorlite Lofts
Permit Application Number: SP23-0001

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 San Marcos BMP Design Manual, which is a design manual for compliance with local City of San Marcos 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.

R.C.E. 66332 Exp. 06-30-25
____________________________________________________________________________________________________________________________________________________________________________________________________________________ Engineer of Work's Signature, PE Number & Expiration Date Gio Posillico
______________________________________________________________________________________________________________________________________________________________________________________________________________ Print Name
Latitude 33 Planning and Engineering
______________________________________________________________________________________________________________________________________________________________________________________________________________ Company
10/23/2023
________________________________________________________________________________________________________ Date
Engineer's Seal:

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
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City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

PDP SWQMP PROJECT OWNER'S CERTIFICATION PAGE
Project Name: Armorlite Lofts
Permit Application Number: SP23-0001

PROJECT OWNER'S CERTIFICATION
This PDP SWQMP has been prepared for Las Posas Ventures, LLC by Latitude 33 Planning & Engineering].

The PDP SWQMP is intended to comply with the PDP requirements of the City of San Marcos BMP Design Manual, which is a design manual for compliance with local City of San Marcos and regional MS4 Permit (California Regional Water Quality Control Board San Diego Region Order No. R9-2015-0100) 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-ininterest 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. ________________________________________________________ Project Owner's Signature
Dan Tate
______________________________________________________________________________________________________________________________________________________________________________________________________________ Print Name
Las Posas Ventures, LLC
______________________________________________________________________________________________________________________________________________________________________________________________________________ Company
________________________________________________________________________________________________________ Date

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
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City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

SUBMITTAL RECORD
Use this Table to keep a record of submittals of this PDP SWQMP. Each time the PDP SWQMP is resubmitted, provide the date and status of the project. In column 4 summarize the changes that have been made or indicate if response to plancheck comments is included. When applicable, insert response to plancheck comments behind this page.

Submittal
Number
Date Project Status Summary of Changes
1 6/6/23 Preliminary Design /
Planning/ CEQA
Final Design
Initial Submittal
2 8/11/23 Preliminary Design /
Planning/ CEQA
Final Design
Resubmittal
3 Preliminary Design /
Planning/ CEQA
Final Design
4 Preliminary Design /
Planning/ CEQA
Final Design

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24

PROJECT VICINITY MAP
Project Name: Armorlite Lofts
Permit Application Number: SP23-0001
City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Applicability of Storm Water Best Management Practices (BMP) Requirements (Storm Water Intake Form for all Development Permit Applications) For detailed information please visit:
http://www.san-marcos.net/departments/development-services/stormwater/development-planning Form I-1
[March 15, 2016]
Project Identification
Project Name: Armorlite Lofts
Description:

A four-story apartment complex above a one-story parking garage with an associated outdoor parking lot.

Permit Application Number (if applicable): SDP23-0003 Date: 6/6/23 Project Address: Armorlite Drive, San Marcos, CA 92069
Determination of Requirements
This form is required as part of the City’s application process. The purpose of this form is to identify potential land development planning storm water requirements that apply to development projects.

Development projects are defined as construction, rehabilitation, redevelopment, or reconstruction of any public or private projects. In addition, the identification of a development project, as it relates to storm water regulations, would truly apply to development and redevelopment activities that have the potential to contact storm water and contribute a source of pollutants, or reduce the natural absorption and infiltration abilities of the land.

To access the BMP Design Manual, Storm Water Quality Management Plan (SWQMP) templates, and other pertinent information related to this program please refer to:
http://www.san-marcos.net/departments/development-services/stormwater/development-planning Please answer each of the following steps below, starting with Step 1 and progressing through each step until reaching "Stop".

Step Answer Progression
Step 1: Based on the above, Is the project a
"development project" (See definition above)?
See Section 1.3 of the BMP Design Manual for
further guidance if necessary.
Yes Go to Step 2.
No Permanent BMP requirements do not apply. No
SWQMP will be required. Provide brief discussion
below. STOP.

Discussion / justification if the project is not a "development project" (e.g., the project includes only interior remodels within an existing building):

Step 2: Is the project a Standard Project, Priority
Development Project (PDP), or exception to PDP
definitions?
To answer this item, complete Form I-2, Project
Type Determination. See Section 1.4 of the BMP
Design Manual in its entirety for guidance.

In addition to Section 1.4, please refer to the
City’s SWQMP Submittal Requirements form.
Standard Project Only Standard Project requirements apply, including Standard Project SWQMP. STOP.
PDP Standard and PDP requirements apply, including
PDP SWQMP. Go to Step 3 on the following page.
Exception to PDP
definitions
Standard Project requirements apply, and any
additional requirements specific to the type of
project. Provide discussion and list any additional
requirements below. Prepare Standard Project
SWQMP. STOP.

Discussion / justification, and additional requirements for exceptions to PDP definitions, if applicable:

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-1 Page 2, Form Date: March 15, 2016
Step 3 (PDPs only). Please answer the list of questions in this section to determine if hydromodification requirements reply to the proposed PDP. Does the project:

Step 3a. Discharge storm water
runoff directly to the Pacific Ocean?
Yes STOP. Hydromodification requirements do not apply. No Continue to Step 3b.

Step 3b. Discharge storm water
runoff directly to an enclosed
embayment, not within protected
areas?
Yes STOP. Hydromodification requirements do not apply. No Continue to Step 3c.

Step 3c. Discharge storm water
runoff directly to a water storage
reservoir or lake, below spillway or
normal operating level?
Yes STOP. Hydromodification requirements do not apply. No Continue to Step 3d.

Step 3d. Discharge storm water
runoff directly to an area identified in
WMAA?
Yes STOP. Hydromodification requirements do not apply. No Hydromodification requirements apply to the project. Go to Step

4. Discussion / justification if hydromodification control requirements do not apply:

Step 4 (PDPs subject to
hydromodification control
requirements only). Does protection
of critical coarse sediment yield areas
apply based on review of WMAA
Potential Critical Coarse Sediment
Yield Area Map?
See Section 6.2 of the BMP Design
Manual for guidance.
Yes Management measures required for protection of critical coarse sediment yield areas (Chapter 6.2).

Stop.
No Management measures not required for protection of critical coarse sediment yield areas.

Provide brief discussion below.

Stop.

Based on review of WMAA Potential Critical Coarse Sediment Yield Area Map, critical coarse sediment yield areas are not located near project site.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Project Type Determination Checklist Form I-2
[March 15, 2016]
Project Information
Project Name/Description: Armorlite Lofts
Permit Application Number (if applicable): Date: 5/9/23 Project Address: Armorlite Drive, San Marcos, CA 92069
Project Type Determination: Standard Project or Priority Development Project (PDP) The project is (select one): New Development Redevelopment The total proposed newly created or replaced impervious area is: _91,690__ ft2 (__2.10___) acres Is the project in any of the following categories, (a) through (f)? Yes No (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.

Yes No (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.

Yes No (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.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-2 Page 2, Form Date: March 15, 2016
Yes No (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 discharging 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; areas designated as Areas of Special Biological Significance by the State Water Board and San Diego Water Board; 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 Copermittees. See BMP Design Manual Section 1.4.2 for additional guidance.

Yes No (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.
(ii) Retail gasoline outlets (RGOs). This category includes RGOs that meet the following criteria: (a) 5,000 square feet or more or (b) a projected Average Daily Traffic (ADT) of 100 or more vehicles per day.

Yes No (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.

Note: See BMP Design Manual Section 1.4.2 for additional guidance.

Does the project meet the definition of one or more of the Priority Development Project categories (a) through (f) listed above?
No – the project is not a Priority Development Project (Standard Project).

Yes – the project is a Priority Development Project (PDP).

The following is for redevelopment PDPs only:

The area of existing (pre-project) impervious area at the project site is: ________ ft2 (A) The total proposed newly created or replaced impervious area is ________ ft2 (B) Percent impervious surface created or replaced (B/A)*100: _______% The percent impervious surface created or replaced is (select one based on the above calculation):
less than or equal to fifty percent (50%) – only new impervious areas are considered PDP OR
greater than fifty percent (50%) – the entire project site is a PDP

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Site Information Checklist
For PDPs
Form I-3B (PDPs)
[March 15, 2016]
Project Summary Information
Project Name Armorlite Lofts
Project Address
Armorlite Drive
San Marcos, California 92069
Assessor's Parcel Number(s) (APN(s)) 219-162-62-00
Permit Application Number
Project Hydrologic Unit Select One:
Santa Margarita 902
San Luis Rey 903
Carlsbad 904
San Dieguito 905
Penasquitos 906
San Diego 907
Pueblo San Diego 908
Sweetwater 909
Otay 910
Tijuana 911
Project Watershed
(Complete Hydrologic Unit, Area, and Subarea
Name with Numeric Identifier)
Hydrologic Unit: Carlsbad
Area: San Marcos
Subarea: Richland #904.52
Parcel Area
(total area of Assessor's Parcel(s) associated
with the project)
___2.44_____ Acres (___106,442___ Square Feet)
Area to be Disturbed by the Project
(Project Area) ___2.44_____ Acres (___106,442___ Square Feet) Project Proposed Impervious Area
(subset of Project Area) ___2.10_____ Acres (___91,690____ Square Feet) Project Proposed Pervious Area
(subset of Project Area) ___0.34_____ Acres (___14,760____ Square Feet) Note: Proposed Impervious Area + Proposed Pervious Area = Area to be Disturbed by the Project.

This may be less than the Parcel Area.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 2 of 10, Form Date: March 15, 2016
Description of Existing Site Condition
Current Status of the Site (select all that apply):
Existing development
Previously graded but not built out
Demolition completed without new construction
Agricultural or other non-impervious use
Vacant, undeveloped/natural
Description / Additional Information:

The existing condition is comprised of undeveloped vegetative area.

Existing Land Cover Includes (select all that apply):
Vegetative Cover
Non-Vegetated Pervious Areas
Impervious Areas
Description / Additional Information:

Underlying Soil belongs to Hydrologic Soil Group (select all that apply):
NRCS Type A
NRCS Type B
NRCS Type C
NRCS Type D
Approximate Depth to Groundwater (GW):
GW Depth < 5 feet
5 feet < GW Depth < 10 feet
10 feet < GW Depth < 20 feet
GW Depth > 20 feet
Existing Natural Hydrologic Features (select all that apply):
Watercourses
Seeps
Springs
Wetlands
None
Description / Additional Information:

This is an undeveloped lot with waist high vegetation that has no evidence of the above natural hydrologic features. There is a high point central to the site, therefore drainage flows in all directions and does not become concentrated on the property.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 3 of 10, Form Date: March 15, 2016
Description of Existing Site Drainage Patterns
How is storm water runoff conveyed from the site? At a minimum, this description should answer:
(1) whether existing drainage conveyance is natural or urban; (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:

1. Natural

2. There are no offsite runoff on this site due to the existing topography. The property appears to be elevated compared to the surrounding property.

3. There is a high point central to the site, therefore drainage flows in all directions. There are two inlets located at the southwest intersection (Las Posas Rd. & Armorlite Dr.) 200' away from property.

4. The runoff has been broken into 3 POC’s in the existing condition:

POC 1 (SW)
POC 2 (W)
POC 3 (NE)

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 4 of 10, Form Date: March 15, 2016
Description of Proposed Site Development
Project Description / Proposed Land Use and/or Activities:

The project proposes construction of a 4-story mixed-use residential/commercial development with a 1- story podium garage, and associated surface improvements including exposed parking areas, pedestrian walking paths, and outdoor amenities. Proposed underground utilities include storm drain, sewer, water, gas, irrigation, electrical, and telecommunications.

List/describe proposed impervious features of the project (e.g., buildings, roadways, parking lots, courtyards, athletic courts, other impervious features):
-Proposed 4-story stacked flats above 1-story parking structure -Private drive aisle
-Parking Stalls
-Private Sidewalk
List/describe proposed pervious features of the project (e.g., landscape areas):
-Landscape areas
-Dog Park
Does the project include grading and changes to site topography? Yes
No
Description / Additional Information:

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 5 of 10, Form Date: March 15, 2016
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:

Post construction surface drainage will be collected via sheet flow. In DMA 1, storm water will sheet to the designated low point in the parking lot and be collected by combination of area drains, trench drains and drain inlet. The flow confluences at the drain inlet and will then convey captured flow to BMP1 MWS (MWS-L-8-20-V). The entirety of drainage from the building footprint will be collected via roof drains and directly piped to BMP 1 MWS. In DMA 2, storm water will sheet flow to a different designated low point in the drive aisle and be captured via BMP 2 MWS (MWS-L-8-8-V). The treated flow from BMP1 and BMP2 will then flow into a storm water detention system under the drive aisle before it ultimately discharges to the existing POC (POC 1). There is 0.09 acres of pervious area, DMA3, considered self-mitigating, that flows south and discharges to the existing landscape parkway via sidewalk underdrain. This runoff eventually reaches the existing storm drain inlet (POC 1) and is accounted for.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 6 of 10, Form Date: March 15, 2016
Identify whether any of the following features, activities, and/or pollutant source areas will be present (select all that apply):
On-site storm drain inlets
Interior floor drains and elevator shaft sump pumps
Interior parking garages
Need for future indoor & structural pest control
Landscape/Outdoor Pesticide Use
Pools, spas, ponds, decorative fountains, and other water features Food service
Refuse areas
Industrial processes
Outdoor storage of equipment or materials
Vehicle and Equipment Cleaning
Vehicle/Equipment Repair and Maintenance
Fuel Dispensing Areas
Loading Docks
Fire Sprinkler Test Water
Miscellaneous Drain or Wash Water
Plazas, sidewalks, and parking lots
Description / Additional Information:

The site will be mixed-use 4-story stacked flats above 1-level podium garage and associated landscaped areas and private parking/drive aisle.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 7 of 10, Form Date: March 15, 2016
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):

Project runoff enters the public storm drain system along Armorlite Drive. Runoff crosses Route 78 and eventually discharges into San Marcos Lake. Runoff eventually enters into the Pacific Ocean via San Marcos Creek and Batiquitos Lagoon.

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:
303(d) Impaired Water Body Pollutant(s)/Stressor(s)
TMDLs / WQIP Highest
Priority Pollutant
San Marcos Creek Benthic Community Effects,
Dichlorodiphenyldichloroethylene (DDE),
Indicator Bacteria, Phosphorus, Toxicity,
Selenium
Nutrients
San Marcos Lake (Upper) Ammonia as N, Copper, Nutrients, Phosphorous
San Marcos Lake (Lower) Indicator Bacteria
San Marcos, Lake, drain to
central southwest fork of Lake
Copper, Indicator Bacteria
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):

Pollutant
Not Applicable to the
Project Site
Expected from the
Project Site
Also a Receiving Water
Pollutant of Concern
Sediment
Nutrients
Heavy Metals
Organic Compounds
Trash & Debris
Oxygen Demanding
Substances
Oil & Grease
Bacteria & Viruses
Pesticides

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 8 of 10, Form Date: March 15, 2016
Hydromodification Management Requirements
Do hydromodification management requirements apply (see Section 1.6 of the BMP Design Manual)? 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.

Description / Additional Information (to be provided if a 'No' answer has been selected above):

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?
Yes
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.b of the SWQMP. 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 SWQMP Exhibit.

Discussion / Additional Information:

Per the CCSYA Exhibit provided in Attachment 2b, there is no course sediment present on site.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 9 of 10, Form Date: March 15, 2016
Flow Control for Post-Project Runoff*
*This Section only required if hydromodification management requirements apply List and describe point(s) of compliance (POCs) for flow control for hydromodification management (see Section 6.3.1). For each POC, provide a POC identification name or number correlating to the project's HMP Exhibit and a receiving channel identification name or number correlating to the project's HMP Exhibit.

POC 1 is the point at which the project’s main private storm drain leaves the site, prior to its connection to the existing public storm drain system within the Armorlite right-of-way. Treated/stored surface runoff from BMPs 1, 2, and 3 (MWS’/Storage Vault) discharges to a proposed cleanout that ultimate connects to the existing storm drain system. POC 2 is self-mitigating pervious landscape area that sheet flows North East of the site, similar to the existing condition drainage pattern. POC 3 is also selfmitigating pervious landscape area that sheet flows west like the existing condition drainage pattern.

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
Yes, the result is the low flow threshold is 0.5Q2
If a geomorphic assessment has been performed, provide title, date, and preparer:

See Channel Screening Analysis performed by Delane Engineering, Inc. titled “Karl Strauss San Marcos Tasting Room and Garden” dated 11/18/19.

Discussion / Additional Information: (optional)

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-3B Page 10 of 10, Form Date: March 15, 2016
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 proposed driveway will require the removal and replacement of the existing storm water management facilities fronting the project site. Per As-Built Dwg No. IP-4883, 12 existing Silva Cells will need to be removed and replaced-in-kind further down Armorlite Drive to the west. Approximately 200 SF of landscape planting area at 3’ wide landscape panel will be installed. The landscape area and respective silva cells will not encroach into the existing bike and pedestrian paths.

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.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Source Control BMP Checklist
for All Development Projects
(Standard Projects and Priority Development Projects)
Form I-4
[March 15, 2016]
Project Identification
Project Name: Armorlite Lofts
Permit Application Number: SDP23-0003
Source Control BMPs
All development projects must implement source control BMPs SC-1 through SC-6 where applicable and feasible. 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.
• "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. Discussion / justification is not required. • "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion / justification must be provided.
• "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).

Discussion / justification may be provided.

Source Control Requirement Applied?
SC-1 Prevention of Illicit Discharges into the MS4 Yes No N/A Discussion / justification if SC-1 not implemented:

SC-2 Storm Drain Stenciling or Signage Yes No N/A Discussion / justification if SC-2 not implemented:

SC-3 Protect Outdoor Materials Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal
Yes No N/A
Discussion / justification if SC-3 not implemented:

SC-4 Protect Materials Stored in Outdoor Work Areas from Rainfall, Run-On, Runoff, and Wind Dispersal
Yes No N/A
Discussion / justification if SC-4 not implemented:

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-4 Page 2 of 2, Form Date: March 15, 2016
Source Control Requirement Applied?
SC-5 Protect Trash Storage Areas from Rainfall, Run-On, Runoff, and Wind Dispersal
Yes No N/A
Discussion / justification if SC-5 not implemented:

SC-6 Additional BMPs Based on Potential Sources of Runoff Pollutants (must answer for each source listed below)
On-site storm drain inlets
Interior floor drains and elevator shaft sump pumps
Interior parking garages
Need for future indoor & structural pest control
Landscape/Outdoor Pesticide Use
Pools, spas, ponds, decorative fountains, and other water features Food service
Refuse areas
Industrial processes
Outdoor storage of equipment or materials
Vehicle and Equipment Cleaning
Vehicle/Equipment Repair and Maintenance
Fuel Dispensing Areas
Loading Docks
Fire Sprinkler Test Water
Miscellaneous Drain or Wash Water
Plazas, sidewalks, and parking lots
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
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.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Site Design BMP Checklist
for All Development Projects
(Standard Projects and Priority Development Projects)
Form I-5
[March 15, 2016]
Project Identification
Project Name: Armorlite Lofts
Permit Application Number: XXXXX
Site Design BMPs
All development projects must implement site design BMPs SD-1 through SD-8 where applicable and feasible. 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.
• "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. Discussion / justification is not required. • "No" means the BMP is applicable to the project but it is not feasible to implement. Discussion / justification must be provided.
• "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).

Discussion / justification may be provided.

Site Design Requirement Applied?
SD-1 Maintain Natural Drainage Pathways and Hydrologic Features Yes No N/A Discussion / justification if SD-1 not implemented:

Existing site was undeveloped. Developed condition proposes entirety of site related discharge to POC

1. SD-2 Conserve Natural Areas, Soils, and Vegetation Yes No N/A Discussion / justification if SD-2 not implemented:

Existing site was undeveloped. Developed condition proposes entirety of site related discharge to POC

1. Permeable landscape areas provided where possible.

SD-3 Minimize Impervious Area Yes No N/A
Discussion / justification if SD-3 not implemented:

SD-4 Minimize Soil Compaction Yes No N/A
Discussion / justification if SD-4 not implemented:

SD-5 Impervious Area Dispersion Yes No N/A
Discussion / justification if SD-5 not implemented:

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-5 Page 2 of 2, Form Date: March 15, 2016
Site Design Requirement Applied?
SD-6 Runoff Collection Yes No N/A
Discussion / justification if SD-6 not implemented:

SD-7 Landscaping with Native or Drought Tolerant Species Yes No N/A Discussion / justification if SD-7 not implemented:

SD-8 Harvesting and Using Precipitation Yes No N/A Discussion / justification if SD-8 not implemented:

There will be no irrigation demand for this project site within 36 hours of a rain event. The proposed structure will not be dual plumbed, so there will be no grey water demand for the project site. Given that the City of San Marcos requires a 36-hr drawdown time for harvest and use, this type of BMP is not feasible for this project.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Summary of PDP Structural BMPs Form I-6 (PDPs)
[March 15, 2016]
Project Identification
Project Name: Armorlite Lofts
Permit Application Number: XXXXX
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 BMPs selected). For projects requiring hydromodification flow control BMPs, indicate whether pollutant control and flow control BMPs are integrated or separate.

This site will utilize 2-MWS, and a stormwater detention vault as sources of structural BMP’s. These BMP’s will collect water from all impervious areas before it is discharged off site.

Flow-thru treatment is required to treat runoff from the proposed development. Biofiltration basins were deemed infeasible due to lack of space within the parkways and grading of the lot. A Modular Wetland Device was chosen for it’s ability to provide biofiltration mitigation with a significantly smaller footprint. See Worksheets B.5-6 for sizing. For HMP mitigation, an underground vault system will be utilized to mitigate the 0.3Q2-Q10 storm events. The Clear Water spreadsheet was used to size the vault system.
(Continue on page 2 as necessary.)

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-6 Page 2 of 8, Form Date: March 15, 2016
(Page reserved for continuation of description of general strategy for structural BMP implementation at the site)
(Continued from page 1)
The implementation strategy was as follows:

Step 1 – The DMAs will require treatment and DCVs were calculated for those DMAs.

Step 2 – Per the included Harvest and Use feasibility screening, Form I-7, the proposed project is considered to be infeasible for harvest and use. Infiltration has been deemed infeasibile per Geotechnical Recommendations (Infiltration Testing & Form I-8).

Step 3 – Two Modified Wetland System’s have been sized for pollutant control and a Stormwater Detention System has been sized for hydromodification purposes for DMA 1/2. See Attachments 1e and 2d for calculations.

Step 4 – A Modified Wetland System, and Stormwater Detention System, been sized and placed accordingly to treat the required runoff generated per the proposed development.

Step 5 – For the MWS, Worksheet B.5-1 and Worksheet B.6-1 have been completed.

Step 6 - See SWQMP hereon.

Step 7 - See "Storm Water Management and Discharge Control Maintenance Agreement" form for O&M information.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-6 Page 3 of 8, Form Date: March 15, 2016
Structural BMP Summary Information
(Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No. 1
Construction Plan Sheet No.

Type of structural BMP:
Retention by harvest and use (HU-1)
Retention by infiltration basin (INF-1)
Retention by bioretention (INF-2)
Retention by permeable pavement (INF-3)
Partial retention by biofiltration with partial retention (PR-1) Biofiltration (BF-1)
Biofiltration with Nutrient Sensitive Media Design (BF-2) Proprietary Biofiltration (BF-3) meeting all requirements of Appendix F Flow-thru treatment control with prior lawful approval to meet earlier PDP requirements (provide BMP type/description in discussion section below)
Flow-thru treatment control included as pre-treatment/forebay for an onsite retention or biofiltration BMP (provide BMP type/description and indicate which onsite retention or biofiltration BMP it serves in discussion section below)
Flow-thru treatment control with alternative compliance (provide BMP type/description in discussion section below)
Detention pond or vault for hydromodification management Other (describe in discussion section below)
Purpose:
Pollutant control only
Hydromodification control only
Combined pollutant control and hydromodification control Pre-treatment/forebay for another structural BMP
Other (describe in discussion section below)
Who will certify construction of this BMP?
Provide name and contact information for the
party responsible to sign BMP verification forms if
required by the [City Engineer] (See Section 1.12 of
the BMP Design Manual)
Gio Posillico, PE | RCE 66332
10731 Treena Street
San Diego, CA 92131
Who will be the final owner of this BMP? Las Posas Ventures, LLC or its successors
705 B Street, Suite 3010
San Diego, CA 92101
Who will maintain this BMP into perpetuity? Las Posas Ventures, LLC or its successors
705 B Street, Suite 3010
San Diego, CA 92101
What is the funding mechanism for maintenance? Las Posas Ventures, LLC or its successors
705 B Street, Suite 3010
San Diego, CA 92101

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-6 Page 4 of 8, Form Date: March 15, 2016
Structural BMP ID No. 1
Construction Plan Sheet No.

Discussion (as needed):

BMP 1: Modular Wetlands System located along landscaped area in west side of parking lot.

BMP 1 (8’x20’ Open Planter Modular Wetlands System) was sized utilizing worksheet B.601 (see calculation worksheets in Attachment 1e). The required minimum treatment flow rate for BMP 1 from worksheet B.6-1 is 0.498 cfs. The proposed BMP 1 has a treatment rate of 0.577 cfs.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-6 Page 5 of 8, Form Date: March 15, 2016
Structural BMP Summary Information
(Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No. 2
Construction Plan Sheet No.

Discussion (as needed):

BMP 2: Modular Wetlands System located in landscaped area near Armorlite right-of-way.

BMP 2 (4’x8’ Modular Wetlands System) was sized utilizing worksheet B.601 (see calculation worksheets in Attachment 1e). The required minimum treatment flow rate for BMP 1 from worksheet B.6-1 is 0.099 cfs. The proposed BMP 1 has a treatment rate of 0.115 cfs.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Form I-6 Page 7 of 8, Form Date: March 15, 2016
Structural BMP Summary Information
(Copy this page as needed to provide information for each individual proposed structural BMP) Structural BMP ID No. 3
Construction Plan Sheet No.

Discussion (as needed):

BMP 3: Storm water detention vault located in the parking lot.

SWMM 5.2 was used to size the vault to meet flow control requirements and is a conjunctive use for 100-yr detention. The proposed vault is 3,350 sq. ft and sized to detain flows from DMA-1, DMA-2, and DMA-3 in order to satisfy HMP requirements when evaluating pre and post condition runoff at POC1.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
ATTACHMENT 1

BACKUP FOR PDP POLLUTANT CONTROL BMPS
This is the cover sheet for Attachment 1.

Indicate which Items are Included behind this cover sheet:

Attachment
Sequence
Contents Checklist
Attachment 1a DMA Exhibit (Required)
See DMA Exhibit Checklist on the back of
this Attachment cover sheet.
Included
Attachment 1b Tabular Summary of DMAs Showing DMA
ID matching DMA Exhibit, DMA Area, and
DMA Type (Required)*
*Provide table in this Attachment OR on
DMA Exhibit in Attachment 1a
Included on DMA Exhibit in
Attachment 1a
Included as Attachment 1b, separate
from DMA Exhibit
Attachment 1c Form I-7, Harvest and Use Feasibility
Screening Checklist (Required unless the
entire project will use infiltration BMPs)
Refer to Appendix B.3-1 of the BMP
Design Manual to complete Form I-7.
Included
Not included because the entire
project will use infiltration BMPs
Attachment 1d Form I-8, Categorization of Infiltration
Feasibility Condition (Required unless the
project will use harvest and use BMPs)
Refer to Appendices C and D of the BMP
Design Manual to complete Form I-8.
Included
Not included because the entire
project will use harvest and use BMPs
Attachment 1e Pollutant Control BMP Design
Worksheets / Calculations (Required)
Refer to Appendices B and E of the BMP
Design Manual for structural pollutant
control BMP design guidelines
Included

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Use this checklist to ensure the required information has been included on the DMA Exhibit:

The DMA Exhibit must identify:
Underlying hydrologic soil group
Approximate depth to groundwater
Existing natural hydrologic features ( watercourses, seeps, springs, wetlands) Critical coarse sediment yield areas to be protected
Existing topography and impervious areas
Existing and proposed site drainage network and connections to drainage offsite Proposed demolition
Proposed grading
Proposed impervious features
Proposed design features and surface treatments used to minimize imperviousness Drainage management area (DMA) boundaries, DMA ID numbers, and DMA areas (square footage or acreage), and DMA type (i.e., drains to BMP, self-retaining, or self-mitigating) Potential pollutant source areas and corresponding required source controls (see Chapter 4, Appendix E.1, and Form I-3B)
Structural BMPs (identify location, type of BMP, and size/detail)

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: August 2021
ATTACHMENT 1a

DMA EXHIBIT

MH MH MH MH MH MHMH MH MH MH MH MH MH MHMH MH MH T D D D I RD
W
H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 1 - BMP Backup\Attach. 1a - DMA Exhibit\1900.00_DMA Exhibit.dwg, 8/10/2023 6:03:29 PM, DWG To PDF.pc3 City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date:August 2021
ATTACHMENT 1c
FORM I-7, HARVEST AND USE FEASIBLITY SCREENING CHECKLIST Appendix I: Forms and Checklists
I-2 February 2023
Harvest and Use Feasibility Checklist Form I-7

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 urinal 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.
[Provide a summary of calculations here]

3. Calculate the DCV using worksheet B-2.1.

DCV = __________ (cubic feet)
3a. Is the 36 hour demand
greater than or equal to the DCV?
 Yes /  No
3b. Is the 36 hour demand greater than

0.25DCV but less than the full DCV?
 Yes /  No
3c. Is the 36 hour demand
less than 0.25DCV?
 Yes
Harvest and use appears to be
feasible. Conduct more detailed
evaluation and sizing
calculations to confirm that DCV
can be used at an adequate rate
to meet drawdown criteria.

Harvest and use may be feasible.

Conduct more detailed evaluation and
sizing calculations to determine
feasibility. Harvest and use may only
be able to be used for a portion of the
site, or (optionally) the storage may
need to be upsized to meet long term
capture targets while draining in
longer than 36 hours.

Harvest and use is
considered to be
infeasible.

Is harvest and use feasible based on further evaluation?  Yes, refer to Appendix E to select and size harvest and use BMPs.  No, select alternate BMPs.
3,683 ¸ ¸ ¸
¸
There will be no irrigation demand for this project site within 36 hours of a rain event. The proposed structure will not be dual plumbed, so there will be no grey water demand for the project site. Given that the City of San Marcos requires a 36 hour draw down time for harvest and use, this type of BMP is not feasible for this project. BMP 1 = 3071, BMP 2 = 612 DCV = 3,683 cubic feet = 27,551 gallons

0.25DC = 921 cubic feet = 6,890 gallons
City of San Marcos PDP SWQMP Template Date: March 15, 2016 ATTACHMENT 1d
FORM I-8, CATEGORIZATION OF INFILTRATION FEASIBILITY CONDITION

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GeoTek, Inc. "Preliminary Geotechnical Evaluation, Eastern Portion of 225 N. Las Posas Road, San Marcos, California 92069," Project No. 3685-SD, dated May 30, 2023.

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GeoTek, Inc. "Preliminary Geotechnical Evaluation, Eastern Portion of 225 N. Las Posas Road, San Marcos, California 92069," Project No. 3685-SD, dated May 30, 2023. X X
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No
Infiltration
Based on the underlying geology, granitic rock is shallow and will create a shallow ground water condition. A review of Geotracker.com did not reveal environmental concerns immediately adjacent to the property.

Although GeoTek does not practice in water rights consultation, infiltration of surface waters into the subsurface does not appear to violate downstream water rights.

City of San Marcos PDP SWQMP Template Date: March 15, 2016 ATTACHMENT 1e

POLLUTION CONTROL BMP DESIGN WORKSHEETS
H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 1 - BMP Backup\Attach. 1e - BMP Calcs & Worksheet\190000 85th % Category # Description i ii iii iv v vi vii viii ix x Units 1 Drainage Basin ID or Name 1 2 unitless
2 85th Percentile 24-hr Storm Depth 0.69 0.69 inches
3 Impervious Surfaces Not Directed to Dispersion Area (C=0.90) 71,735 19,358 sq-ft 4 Semi-Pervious Surfaces Not Serving as Dispersion Area (C=0.30) sq-ft 5 Engineered 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 Dispersion Area (C=0.14) sq-ft 8 Natural Type C Soil Not Serving as Dispersion Area (C=0.23) 6,111 5,403 sq-ft 9 Natural Type D Soil Not Serving as Dispersion Area (C=0.30) sq-ft 10 Does Tributary Incorporate Dispersion, Tree Wells, and/or Rain Barrels? No No No No No No No No No No yes/no 11 Impervious Surfaces Directed to Dispersion Area per SD-B (Ci=0.90) sq-ft 12 Semi-Pervious Surfaces Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft 13 Engineered Pervious Surfaces Serving 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-ft 16 Natural Type C Soil Serving as Dispersion Area per SD-B (Ci=0.23) sq-ft 17 Natural Type D Soil Serving as Dispersion Area per SD-B (Ci=0.30) sq-ft 18 Number of Tree Wells Proposed per SD-A #
19 Average Mature Tree Canopy Diameter ft
20 Number of Rain Barrels Proposed per SD-E #
21 Average Rain Barrel Size gal
22 Total Tributary Area 77,846 24,761 0 0 0 0 0 0 0 0 sq-ft 23 Initial Runoff Factor for Standard Drainage Areas 0.85 0.75 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless 24 Initial Runoff Factor for Dispersed & Dispersion Areas 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless 25 Initial Weighted Runoff Factor 0.85 0.75 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless 26 Initial Design Capture Volume 3,805 1,068 0 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 Impervious Area to Pervious Dispersion Area n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a ratio 30 Adjustment 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 After Dispersion Techniques 0.85 0.75 n/a n/a n/a n/a n/a n/a n/a n/a unitless 32 Design Capture Volume After Dispersion Techniques 3,805 1,068 0 0 0 0 0 0 0 0 cubic-feet 33 Total Tree Well Volume Reduction 0 0 0 0 0 0 0 0 0 0 cubic-feet 34 Total Rain Barrel Volume Reduction 0 0 0 0 0 0 0 0 0 0 cubic-feet 35 Final Adjusted Runoff Factor 0.85 0.75 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 unitless 36 Final Effective Tributary Area 66,169 18,571 0 0 0 0 0 0 0 0 sq-ft 37 Initial Design Capture Volume Retained by Site Design Elements 0 0 0 0 0 0 0 0 0 0 cubic-feet 38 Final Design Capture Volume Tributary to BMP 3,805 1,068 0 0 0 0 0 0 0 0 cubic-feet False
False
Automated Worksheet B.1: Calculation of Design Capture Volume (V2.0) Dispersion Area,
Tree Well & Rain
Barrel Inputs
(Optional)
Standard Drainage
Basin Inputs
Results
Tree & Barrel
Adjustments
Initial Runoff Factor
Calculation
Dispersion Area
Adjustments
No Warning Messages
Category # Description i ii iii iv v vi vii viii ix x Units 1 Drainage Basin ID or Name 1 2 - - - - - - - - unitless 2 85th Percentile Rainfall Depth 0.69 0.69 - - - - - - - - inches 3 Predominant NRCS Soil Type Within BMP Location C C unitless 4 Is proposed BMP location Restricted or Unrestricted for Infiltration Activities? Restricted Restricted unitless 5 Nature of Restriction Soil Type Soil Type unitless
6 Do Minimum Retention Requirements Apply to this Project? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes yes/no 7 Are Habitable Structures Greater than 9 Stories Proposed? No No yes/no 8 Has Geotechnical Engineer Performed an Infiltration Analysis? Yes Yes yes/no 9 Design Infiltration Rate Recommended by Geotechnical Engineer 0.000 0.000 in/hr 10 Design Infiltration Rate Used To Determine Retention Requirements 0.000 0.000 - - - - - - - - in/hr 11 Percent of Average Annual Runoff that Must be Retained within DMA 1.5% 1.5% - - - - - - - - percentage 12 Fraction of DCV Requiring Retention 0.01 0.01 - - - - - - - - ratio 13 Required Retention Volume 38 11 - - - - - - - - cubic-feet False
False
Automated Worksheet B.2: Retention Requirements (V2.0)
Advanced
Analysis
Basic Analysis
Result
No Warning Messages
Category # Description i ii Units
0 Drainage Basin ID or Name 1 2 unitless
1 Final Effective Tributary Area 66,169 18,571 sq-ft
2 Final Adjusted Runoff Factor 0.85 0.75 unitless
3 Final Design Capture Volume Tributary to BMP 3,805 1,068 cubic-feet 4 Volume Effectively Retained and/or Biofiltered 100 100 cubic-feet 5 Deficit of Effectively Treated Stormwater Requiring Flow-Thru Treatment -3,705 -968 cubic-feet 6 Maximum Rated Water Quality Flow Rate of Proposed BMP 0.577 0.231 CFS 7 Adjustment Factor 1.50 1.50 unitless
8 Design Rainfall Intensity for Flow-Thru BMPs 0.20 0.20 in/hr 9 Water Quality Flow Rate Requiring Flow-Thru Treatment 0.456 0.128 CFS Result 10 Is Flow-Thru BMP Adequately Sized? Yes Yes unitless Flow-Thru
BMP Inputs
Flow Rate
Calculations
Worksheet B.3 - Sizing Modular Wetland System

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P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net
2018
Project: All Related
Subject: MWS Linear BMP Classification Per San Diego Manual To Whom it May Concern:

Based upon definitions of Biofiltration as found in Section 2.2.1 and Appendix F of the Manual the MWS Linear meets the criteria to be classified as biofiltration and therefore is not flow through treatment and thus does not trigger the need for alternative compliance. The MWS Linear has GULD approval for basic, phosphorus and enhanced treatment under the TAPE approval. The system is certified under the TAPE approval at a loading rate of 1 gpm/sq ft for all three pollutant categories. This is consistent with the performance criteria related to the performance of Appendix F.

Let us first address the comment regarding the MWS (referring to the Modular Wetland System Linear) being flow through treatment. To do so let us look at the definition of biofiltration as provided by the Design Manual which states:
“For situations where onsite retention of the 85th percentile storm volume is not feasible, biofiltration must be provided to satisfy specific “biofiltration standards” i.e. a set of selection, sizing, design and operation and maintenance (O&M) criteria that must be met for a BMP to be considered a “biofiltration BMP” – see Section 2.2.1 and Appendix F.” If we look at section 2.2.2 Storm Water Pollutant Control Performance Standard it states:
“(i) If it is not technically feasible to implement retention BMPs for the full DCV onsite for a PDP, then the PDP shall utilize biofiltration BMPs for the remaining volume not reliably retained. Biofiltration BMPs must be designed as described in Appendix F to have an appropriate hydraulic loading rate to maximize storm water retention and pollutant removal, as well as to prevent erosion, scour, and channeling within the BMP, and must be sized to:
[a]. Treat 1.5 times the DCV not reliably retained onsite, OR [b]. Treat the DCV not reliably retained onsite with a flow-thru design that has a total volume, including pore spaces and pre-filter detention volume, sized to hold at least 0.75 times the portion of the DCV not reliably retained onsite.”
P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net
As the manual states Biofiltration BMPs must be designed as described in Appendix F which states:
“A project applicant must be able to affirmatively demonstrate that a given BMP is designed and sized in a manner consistent with this definition to be considered as a “biofiltration BMP” as part of a compliant storm water management plan.”
“This appendix contains a checklist of the key underlying criteria that must be met for a BMP to be considered a biofiltration BMP. The purpose of this checklist is to facilitate consistent review and approval of biofiltration BMPs that meet the “biofiltration standard” defined by the MS4 Permit.” “This checklist includes specific design criteria that are essential to defining a system as a biofiltration BMP; however it does not present a complete design basis. This checklist was used to develop BMP Fact Sheets for PR-1 biofiltration with partial retention and BF-1 biofiltration, which do present a complete design basis. Therefore, biofiltration BMPs that substantially meet all aspects of the Fact sheets PR-1 or BF-1 should be able to complete this checklist without additional documentation beyond what would already be required for a project submittal.”
“Other biofiltration BMP designs (including both non-proprietary and proprietary designs) may also meet the underlying MS4 Permit requirements to be considered biofiltration BMPs. These BMPs may be classified as biofiltration BMPs if they (1) meet the minimum design criteria listed in this appendix, including the pollutant treatment performance standard in Appendix F.1, (2) are designed and maintained in a manner consistent with their performance certifications (See explanation in Appendix F.2), if applicable, and (3) are acceptable at the discretion of the [City Engineer]. The applicant may be required to provide additional studies and/or required to meet additional design criteria beyond the scope of this document in order to demonstrate that these criteria are met.” As stated the Biofiltration BMP must meet three objectives. The following outlines how the Modular Wetland System Linear meets these criteria.

Minimum Design Criteria

1. Biofiltration BMPs shall be allowed only as described in the BMP selection process in this manual (i.e., retention feasibility hierarchy).
a. The Modular Wetland System Linear (MWS Linear) is only being proposed on plans when retention via infiltration or reuse is proven infeasible. Conditions such as soils with little to no infiltration rate or sites in which insufficient landscaping warrant to successful implementation of reuse systems.

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net

2. Biofiltration BMPs must be sized using acceptable sizing methods described in this manual. a. Section B.5.2 Basis for Minimum Sizing Factor for Biofiltration BMPs states:
“The MS4 Permit describes conceptual performance goals for biofiltration BMPs and specifies numeric criteria for sizing biofiltration BMPs (See Section 2.2.1 of this Manual).

However, the MS4 Permit does not define a specific footprint sizing factor or design profile that must be provided for the BMP to be considered “biofiltration.” “Additionally, it does not apply to alternative biofiltration designs that utilize the checklist in Appendix F (Biofiltration Standard and Checklist). Acceptable alternative designs (such as proprietary systems meeting Appendix F criteria) typically include design features intended to allow acceptable performance with a smaller footprint and have undergone field scale testing to evaluate performance and required O&M frequency.”
As stated in the Manual alternative biofiltration designs are allowed. The MWS Linear therefore qualifies as a biofiltration BMP under this definition as it has both undergone field scale testing (TAPE tested and approved with a GULD) and provides requirements on O&M frequency. In addition, the MWS Linear can be sized to treat either 1.5 times the DCV not reliably retained onsite OR 1.0 times the portion of the DCV not reliably retained onsite; and additionally check that the system has a total static (i.e. non-routed) storage volume, including pore spaces and pre-filter detention volume to at least 0.75 times the portion of the DCV not reliably retained onsite.

3. Biofiltration BMPs must be sited and designed to achieve maximum feasible infiltration and evapotranspiration.
a. The MWS Linear is utilized and placed in the same manner as other types of biofiltration systems. As with other biofiltration systems the MWS Linear includes and underdrain for the remaining portion of the DCV that is not retained via incidental infiltration (as biofiltration if infiltration is not feasible due to poor soils) and evapotranspiration. The MWS Linear can be design with an open bottom to maximize this incidental infiltration. The only exception to this, as with other biofiltration BMPs, is when the geotechnical consultant recommends an impervious liner be used due to specific soil conditions such as expansive clays. Additionally, the MWS Linear utilizes an amended media that is much more porous than the standard prescribed biofiltration media which is a mix of sand and compost. 100% of the media uses in the MWS Linear has interparticle voids of 48% plus and 24% internal void space for each media particle. This is much greater than the sand which has interparticle voids of 35% and internal voids of 0%. As such, the MWS Linear retains greater moisture which allows for greater volume retention and ultimately evapotranspiration via respiration of the contained vegetation.

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net

4. Biofiltration BMPs must be designed with a hydraulic loading rate to maximize pollutant retention, preserve pollutant control/sequestration processes, and minimize potential for pollutant washout. a. The manual states:
“Alternatively, for proprietary designs and custom media mixes not meeting the media specifications contained in the City or County LID Manual, field scale testing data are provided to demonstrate that proposed media meets the pollutant treatment performance criteria in Section F.1 below.”
The MWS Linear has been tested under the Washington State TAPE protocol which is full scale field testing and has received General Use Level Designation under that protocol. Table F.1-1, as shown below, requires a biofiltration BMP to have Basic Treatment, Phosphorus Treatment, and Enhanced Treatment under this protocol. The MWS Linear has GULD approval for all three and therefore meets this minimum requirement 4. A copy of the TAPE approval has been attached to this document.

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net

5. Biofiltration BMPs must be designed to promote appropriate biological activity to support and maintain treatment processes.
a. The MWS Linear an advanced vegetated biofiltration system based that promote biological processes found in both upland bioretention systems and wetlands. The system utilizes an advanced horizontal flow design to ensure maximum contact with the vegetation root mass.

Bacterial growth, supported by the root system in the wetland chamber, performs a number of treatment processes. These vary as a function of moisture, temperature, pH, salinity, and pollutant concentrations. Biologically available forms of nitrogen, phosphorus, and carbon are actively taken into the cells of vegetation and bacteria, and used for metabolic processes (i.e., energy production and growth). Nitrogen and phosphorus are actively taken up as nutrients that are vital for a number of cell functions, growth, and energy production. These processes remove metabolites from the media during and between storm events, making the media available to capture more nutrients from subsequent storms. b. Soil organisms in the wetland chamber can break down a wide array of organic compounds into less toxic forms or completely break them down into carbon dioxide and water (Means and Hinchee 1994). Bacteria can also cause metals to precipitate out as salts, bind them within organic material, and accumulate metals in nodules within the cells. Finally, plant growth may metabolize many pollutants, sequester them or rendering them less toxic (Reeves and Baker 2000).
c. Following are pictures from the plants pulled from a MWS Linear after only 14 months of growth. The media used in the system is designed to maximize biological activity:

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net

6. Biofiltration BMPs must be designed to prevent erosion, scour, and channeling within the BMP. a. The MWS Linear is a self-contained system with a pre-treatment chamber. Unlike other biofiltration BMPs erosion, scour, and channeling with in the BMP is not an issue. Following is a diagram of the BMP. The system pre-treatment chamber prevent any erosion or scour. The system downstream orifice control prevents channeling of the media:

7. Biofiltration BMP must include operations and maintenance design features and planning considerations to provide for continued effectiveness of pollutant and flow control functions. a. The MWS Linear provides activation along with the first year of maintenance and inspection free on all installation in the county of San Diego. Unlike other biofiltration BMPs the City and Co-permitees can be assured the system is being properly installed and maintained. The first year of inspections is used the gauge the amount of loading in the system and this information is used to set appropriate maintenance interval for subsequent years. Attached is a copy of the maintenance manual for the MWS Linear.

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net
Designed & Maintained Consistent with their Performance Certifications We are in agreement that all BMPs should be designed in a manner consistent with the TAPE certification.

The MWS Linear is sized in accordance with the TAPE GULD approval which provides certification at a loading rate of 1 gpm/sq ft (100 in/hr) for Basic, Phosphorus and Enhanced treatment. In addition, as stated previously, Modular Wetland System, Inc. provide activation of all system installed in San Diego County along with the first year of inspections and maintenance to ensure appropriate function. As previously stated, a copy of the TAPE GULD approval is attached to support this claim.

Additionally, it should be noted that the manual allows for biofiltration BMPs to be sized in either volume based (DCV) or flow based design. The manual states in section F.2.2 Sizing of Flow-Based Biofiltration BMPs:
“This sizing method is only available when the BMP meets the pollutant treatment performance standard in Appendix F.1.”
“Proprietary biofiltration BMPs are typically designed as a flow-based BMPs (i.e., a constant treatment capacity with negligible storage volume). Additionally, proprietary biofiltration is only acceptable if no infiltration is feasible and where site-specific documentation demonstrates that the use of larger footprint biofiltration BMPs would be infeasible. The applicable sizing method for biofiltration is therefore reduced to: Treat 1.5 times the DCV.”
“The following steps should be followed to demonstrate that the system is sized to treat 1.5 times the DCV.”

1. Calculate the flow rate required to meet the pollutant treatment performance standard without scaling for the 1.5 factor. Options include either:
- Calculate the runoff flow rate from a 0.2 inch per hour uniform intensity precipitation event (See methodology Appendix B.6.3), or - Conduct a continuous simulation analysis to compute the size required to capture and treat 80 percent of average annual runoff; for small catchments, 5-minute precipitation data should be used to account for short time of concentration.

Nearest rain gage with 5-minute precipitation data is allowed for this analysis.

P O Box 869 Oceanside CA 92049
(760) 433-7640 ● Fax (760) 433-3176
www.BioCleanEnvironmental.net

2. Multiply the flow rate from Step 1 by 1.5 to compute the design flow rate for the biofiltration system.

3. Based on the conditions of certification/verification (discussed above), establish the design capacity, as a flow rate, of a given sized unit.

4. Demonstrates that an appropriate unit size and number of units is provided to provide a flow rate that meets the required flow rate from Step 2.

In conclusion, we have closely followed the process and protocol for showing the MWS Linear meets all the criteria to be accepted as Biofiltration as found in Appendix F.

If you have any questions please feel free to contact us directly.

Sincerely,
Sean M. Hasan
Manager San Diego/Riverside, CA
Bio Clean Environmental Services, Inc.

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City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
ATTACHMENT 2

BACKUP FOR PDP HYDROMODIFICATION CONTROL MEASURES
This is the cover sheet for Attachment 2.
Mark this box if this attachment is empty because the project is exempt from PDP hydromodification management requirements.

Indicate which Items are Included behind this cover sheet:

Attachment
Sequence
Contents Checklist
Attachment 2a Hydromodification Management Exhibit
(Required)
Included
See Hydromodification Management
Exhibit Checklist on the back of this
Attachment cover sheet.

Attachment 2b Management of Critical Coarse Sediment
Yield Areas (WMAA Exhibit is required,
additional analyses are optional)
See Section 6.2 of the BMP Design
Manual.
Exhibit showing project drainage
boundaries marked on WMAA Critical
Coarse Sediment Yield Area Map
(Required)
Optional analyses for Critical Coarse
Sediment Yield Area Determination
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 Receiving
Channels (Optional)
See Section 6.3.4 of the BMP Design
Manual.
Not performed
Included
Submitted as separate stand-alone
document
Attachment 2d Flow Control Facility Design, including
Structural BMP Drawdown Calculations
and Overflow Design Summary
(Required)
See Chapter 6 and Appendix G of the
BMP Design Manual
Included
Submitted as separate stand-alone
document
Attachment 2e Vector Control Plan (Required when
structural BMPs will not drain in 96
hours)
Included
Not required because BMPs will drain
in less than 96 hours

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Use this checklist to ensure the required information has been included on the Hydromodification Management Exhibit:

The Hydromodification Management Exhibit must identify:
Underlying hydrologic soil group
Approximate depth to groundwater
Existing natural hydrologic features ( watercourses, seeps, springs, wetlands) Critical coarse sediment yield areas to be protected
Existing topography
Existing and proposed site drainage network and connections to drainage offsite Proposed grading
Proposed impervious features
Proposed design features and surface treatments used to minimize imperviousness Point(s) of Compliance (POC) for Hydromodification Management Existing and proposed drainage boundary and drainage area to each POC (when necessary, create separate exhibits for pre-development and post-project conditions) Structural BMPs for hydromodification management (identify location, type of BMP, and size/detail)

City of San Marcos PDP SWQMP Template Date: March 15, 2016 ATTACHMENT 2a

HYDROMODIFICATION MANAGEMENT EXHIBITS

MH MH MH MHMH MH MH MH MH MH MHMH MH MH T D D D I
RD
W
H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 2 - HMP Backup\Attach. 2a - HMP Exhibit\1900.00_HMP Exhibit.dwg, 8/10/2023 7:47:35 PM, DWG To PDF.pc3 ATTACHMENT 2b

MANAGEMENT OF CRITICAL COARSE SEDIMENT YIELD AREAS

ATTACHMENT 2c

GEOMORPHIC ASSESSMENT OF RECEIVING CHANNELS
Prepared by Delane Engineering
1 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

CHANNEL SCREENING ANALYSIS

KARL STRAUSS SAN MARCOS

TASTING ROOM AND GARDEN
ARMORLITE DR.

SAN MARCOS, CA 92069
ASSESSOR' S PARCEL NUMBER(S):
219-163-60
ENGINEER OF WORK:

BRIAN P. WIESE, P.E., LICENSE # C80674
EXPIRATION DATE: 03/31/2021
PREPARED FOR:

Karl Strauss Brewing Co.
5965 Santa Fe Street, Suite E
San Diego, CA 92109
PREPARED BY:

Delane Engineering, Inc.
4909 Murphy Canyon Road, Suite 330
San Diego, CA 92123
619-535-0602
DATE:

November 18, 2019
2 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 TABLE OF CONTENTS:

1.0 Introduction

2.0 Office Assessment

3.0 Analysis Domain

4.0 Field Screening
Vertical Susceptibility
Lateral Susceptibility

5.0 Conclusion
ATTACHMENTS:

ATTACHMENT A: Vicinity Map
ATTACHMENT B: Field Assessment Photographs
ATTACHMENT C: Form 1: Initial Desktop Analysis
ATTACHMENT D: Form 3: Vertical Susceptibility Field Sheet ATTACHMENT E: Form 4: Lateral Susceptibility Field Sheet ATTACHMENT F: Form 6: Probability of Mass Wasting Bank Failure 3 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

1.0 Introduction
A new brewery with tasting room, garden, food truck staging areas, and an associated parking lot is being proposed by Karl Strauss Brewing Company on a

1.51 acre site at Los Posas Road and Los Vallecitos Blvd inthe City of San Marcos.

Runoff from the site is discharged via lateral into an existing 72” pipe recently constructed as part of the adjacent Palomar Station development. The 72” pipe is part of the public storm drain system that flows in a generally southerly direction before discharging into a vegetated channel, referred to herein as Los Posas Creek. See Attachment A for vicinity map showing project site in relation to Los Posas Creek.

The project is subject to hydromodification requirements as described in Chapter 6 of the City of San Marcos BMP Design Manual, the purpose of which is to minimize the potential of storm water discharges from the MS4 from causing altered flow regimes and excessive downstream erosion in receiving waters. To meet this requirement the project must provide flow control for post-project runoff to meet the flow control performance standard. The flow control performance standard covers flow rates ranging from a lower flow threshold of 10 percent, 30 percent or 50 percent of the pre -development 2-year runoff event (0.1Q2, 0.3Q2, or

0.5Q2) up to the pre-development 10-year runoff event (Q10). The determination of the low flow threshold depends on the erosion susceptibility of the receiving stream with 0.1Q2 for projects discharging to streams with high susceptibility to erosion ( also the default when a channel susceptibility study has not been prepared), 0.3Q2 for projects discharging to streams with medium susceptibility to erosion, and 0.5Q2 for projects discharging to streams with low susceptibility to erosion
As described in section 6.3.4 of the San Marcos BMP Manual, the use of a higher low flow threshold of 0.3Q2 or 0.5Q2 must be supported by a channel screening report based on a tool developed by the Southern California Coastal Water Research Project (SCCWRP), documented in SCCWRP’ s Technical Report 606 TR 606), dated March 2010, “ Hydromodification Screening Tools: Field Manual for Assessing Channel Susceptibility.” This study follows the methodology of the SCCWRP in order to determine the susceptibility of Los Posas Creek, the results of which can be used to establish the required flow control sizing for the project.

2.0 Office Assessment
Although the screening tool presented in TR 606 is predominantly designed for field-based assessment, it requires some preparatory office work to provide context and familiarity with the site prior to conducting the field evaluation. A satellite image is provided in Attachment A which shows features of the overall setting such as vegetation coverage, grade -control locations, human influences, and existing infrastructure.
4 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 The office assessment also requires an initial desktop analysis, the results of which are provided on Form 1 in Attachment C. Inputs for the drainage area and mean annual precipitation where determined from StreamStats, a Web -based GIS application that provides users access to USGS Data (StreamStats report provided in Attachment C). The valley width and valley slope were determined from City of San Marcos bare earth elevation contour information (2 -ft) from 2009.

3.0 Analysis Domain
As defined in the San Marcos BMP Manual, the receiving stream is the location where runoff from the project is discharged to natural or un-lined channels. This occurs at the outfall of Los Posas Creek from a triple box culvert on the west side of Los Posas Road, approximately 500ft south of the intersection of Linda Vista Drive. This is the upstream limit of analysis as it is where the open , unlined channel begins (Photos 1, 2).

Per criteria in TR 606, the downstream extent of analysis is determined to be the closest of the following:

At least one reach downstream of the first grade -control point Tidal backwater/lentic waterbody
Equal order tributary
A 2-fold increase in drainage area
The nearest lentic waterbody is Lake San Marcos, approximately 5,000 ft downstream and an equal order tributary/2 -fold increase in drainage area does not occur until the confluence with San Marcos Creek approximately 2,000 ft downstream. The first grade control point is approximately 400 ft downstream where a small channel discharges from the east and the main channel shows distinct changes, in particular to bank slope. Although analysis is only required for one reach downstream of this location, the downstream extent selected was the crossing beneath San Marcos Boulevard (Photo 14) as this is a logical divide which may offer grade control, cause discontinuities in the conveyance of water or sediment, etc.

Although the 1,200 ft analysis domain is longer than the 656 feet (200m) maximum reach length for assigning a susceptibility rating per TR 606, this section of Los Posas Creek is an engineered channel which aerial photos and field reconnaissance show to be relatively uniform. Dividing the analysis domain into additional subreaches will not produce significantly different results.

4.0 Field Screening
A field assessment of the analysis domain was done on November 8, 2019. Much of the study area contained dense vegetation (Photos 2, 11) which limited access to some areas of the channel. The areas of the channel that were accessible for assessment were typically moderately vegetated (Photo 12). Evaluating just these 5 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 areas errs conservative as additional vegetation helps hold soil together and reduces flow velocity, further reducing susceptibility to erosion. Aerial photographs of the area dating back over 20 years show that vegetation coverage along the channel has increased with time.

The field screening tool uses a combination of relatively simple, but quantitative field indicators as input parameters to a set of decision trees. These decision trees, along with checklists, tables and calculations, follow a logical progression for assigning a susceptibility rating of Low, Medium, High, or Very High to the channel reach being assessed. susceptibility ratings are assigned independently to the vertical and lateral conditions, the more conservative of which is used to determine the erosion susceptibility ofthe channel. Vertical stability is aprerequisite for lateral stability because a stream that incises can increase bank heights to the point of collapse and channel widening. Accordingly, vertical susceptibility is assessed first because it affects the lateral rating in most instances.

Vertical Susceptibility
The decision tree and associated checklists and calculations for determining a vertical susceptibility rating ( Form 3 from TR 606) are in Attachment D. The purpose of the vertical susceptibility decision tree is to assess the state of the channel bed with a particular focus on the risk of incision . There are three potential states of bed material based on broad classes of armoring potential, described in TR 606 as follows:

Labile Bed – sand-dominated bed, little resistant substrate Transitional/Intermediate Bed – bed typically characterized by gravel/small cobble, intermediate level of resistance of the substrate and uncertain potential for armoring
Threshold Bed ( Course/Armored Bed) – armored with large cobbles or larger bed material or highly-resistant bed substrate
The decision tree includes a photographic supplement to help make the determination of bed material. Through field observation it was determined thatthe bed was not sand-dominated nor sufficiently armored. Although the channel is not consistently armored, some larger cobble was observed along the banks adjacent to the initial discharge location into the channel (Photos 3, 4). Concrete armoring of the bed was observed upstream of the culvert crossing beneath San Marcos Blvd, at the downstream end of the analysis domain ( Photos 13, 14). For the majority of the analysis domain, a surface veneer and dense vegetation cause uncertainty in the potential for armoring. Penetration of the soil was difficult and the limited substrate bed material that was able to be observed contained gravel Photo 5), both of which are consistent with a Transitional/Intermediate Bed. 6 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Intermediate beds require the following additional risk factors to be examined before a vertical rating can be assigned.

Armoring Potential – The channel was determined to have intermediate armoring potential based on Form 3 Checklist 1. This is a result of the unknown condition of the substrate due to surface veneer and vegetation.

Grade Control – The channel was determined to have intermediate grade control based on Form 3 Checklist 2. Man-made grade control is present at each end of the analysis domain in the form of culverts. Both appear in good condition with no apparent undermining, flanking, etc. The dense vegetation between functions as a continuous natural grade control and the flat valley slope determined as part of the desktop analysis mean that grade control will have an affect across a longer distance. The determination of intermediate instead of effective grade control was made to err conservative due to potential evidence of erosion observed on a few short stretches of bank along the channel (Photo 6)
Proximity to incision/braiding threshold – The channel was determined to have a screening index score of B per Form 3 Table 1as the surface veneer and vegetation result in hardpan/d50 that is indeterminate.

The results of the additional risk factors were translated to numeric values and used as inputs into a formula for coming up with an overall vertical rating as shown at the end of Form 3. The vertical rating was determined to be 6, which falls into the range of MEDIUM VERTICAL SUSCEPTIBILITY.

Lateral Susceptibility
The decision tree for determining a lateral susceptibility rating ( Form 4 from TR 606) is in Attachment E. The purpose of the lateral decision tree is to assess the state of the channel banks with a particular focus on the risk of widening. Although the channel is straight and linear, it is laterally adjustabl e due to lack of armoring.

However, the field assessment found no evidence of lateral adjustments occurring.

The banks werefound tobe moderately to highly consolidated basedonthe criteria in TR 606. They are hard when dry with little evidence of crumbling and bank material stratification is not prevalent or contributing to failure. Although there was no evidence of extensive mass wasting occurring along the channel, TR 606 methodology requires thattheprobability of mass wasting bank failurebeanalyzed to determine whether the risk of bank failure is less than or greater than 10%.

This risk threshold determination was made using the Probability Mass Wasting diagram in Attachment F (Form 6 Figure 1 from TR 606). The inputs for bank angle and height were determined based on measurements taken in the field Photos 7-10). Assessment was done in several locations along the analysis 7 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 domain with generally consistent results, with the more conservative of the measurements being used as inputs. Even erring conservation, it was determined that the probability of mass wasting bank failure is less than 10%.

The vertical rating is medium and the VWI (Valley Width Index) was calculated to be greater than 2 during the initial desktop analysis. As a result, the channel was determined to have MEDIUM LATERAL SUSCEPTIBILITY.

5.0 Conclusion
The methodology in the SCCWRP’s Technical Report 606 was used to analyze the section of Los Posas Creek from the initial discharge into an unlined channel west of Los Posas Road to the culvert crossing beneath San Marcos Blvd.

Results of the analysis indicate that the channel has medium vertical and lateral susceptibility. As such, the Karl Straus San Marcos project should design flow control facilities based on a maximum low flow threshold of 0.3Q2 which is indicative of a receiving channel with MEDIUM SUSCEPTIBILITY to erosion.

5 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT A

VICINITY MAP

LAKE SAN MARCOS

HYDROMOD EXEMPT PER WMAA)

SAN MARCOS CREEK
LOW SUCEPTIBILITY PER 2011

SPECIFIC PLAN STUDY)

PROJECT
SITE

LOS POSAS CREEK

UNDERGROUND PIPE)

LOS POSAS CREEK

ENGINEERED CHANNEL)

ANALYSIS DOMAIN

6 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT B

PHOTOGRAPHS

HMENT B

FIELD ASSESSMENT

10 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 1: Looking upstream at beginning of analysis domain Photo 2: Looking downstream from beginning of analysis domain

11 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 3: Evidence of bank armoring at beginning of analysis domain Photo 4: Evidence of bank armoring at beginning of analysis domain

12 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 5: Channel bed material
Photo 6: Evidence of possible erosion

13 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 7: Typical left bank slope
Photo 8: Typical left bank height

14 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 9: Typical right bank slope
Photo 10: Typical right bank height

15 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 11: Typical heavily vegetated section of channel
Photo 12: Typical moderately vegetated section of channel

16 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415 Photo 13: Armoring at downstream end of domain of analysis Photo 14: Armoring at downstream end of domain of analysis

14 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT C
FORM 1: INITIAL DESKTOP ANALYSIS

user: stream:

33.1360
117.1951
FORM 1:

Variable units Value Description & Source

2.6 15.8

0.005
127
350

9.90 0.016

19.08 6.65

INITIAL DESKTOP ANALYSIS
S.CA Hydromodification Screening Tool version 1.0
P
Mean annual
precipitation inches area-weighted annual precipitation via USGS delineated polygons using records from 1900 to 1960 (which was more significant in hydrologic models than polygons delineated from shorter record lengths) Brian Wiese, PE
Symbol
GIS metrics and screening indices (for detailed instructions/examples see ' Field Screening Companion Document') contributing drainage area to screening location via published HUCs and/or 30-m (or better) National Elevation Data serverADrainage NED), USGS seamless Area mi2
Sv Valley slope m/m
valley slope at site via NED, measured over a relatively homogeneous valley segment as indicated by slope, hillslope coupling/ confinement, valley alignment, confluences, etc., over a distance of up to ~500 meters or 10% of the mainchannel length (whatever is smaller) VWI Valley width
index m/m VWI = Wv / Wref
Wv Valley width meters
valley bottom width at site between natural valley walls as dictated by clear breaks in hillslope on NED raster, irrespective of potential armoring from floodplain encroachement, levees, etc. (imprecise measurements have negligible effect on rating in wide valleys where VWI >>2, as defined in lateral decision tree) Q10cfs
10-year mobility
index
Q10 10-year peak
flow m3/s Q10 = 0.0283 * Q10cfs
10-year peak
flow, US units ft3/s Q10cfs = 18.2 * A

0.87 * P0.77 ( Hawley and Bledsoe, In review)
m1.5/s0.5
INDEX = Sv * Q10 0.5
longitude (decimal degrees):
latitude (decimal degrees):

Karl Strauss San Marcos discharge location at Los Posas Creek Wref Reference width meters Wref = 6.99 * Q10 0.438
INDEX

11/13/2019 StreamStats
https:// streamstats. usgs. gov/ ss/ 1/2
039 Los Posas Creek StreamStats Report
Basin Characteristics
Parameter Code Parameter Description Value Unit
BSLDEM30M Mean basin slope computed from 30 m DEM 8 .79 percent DRNAREA Area that drains to a point on a stream 2 .6 square miles PRECIP Mean Annual Precipitation 15 .8 inches
USGS Data Disclaimer: Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey ( USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.

Region ID : CA
Workspace ID : CA20191113182948989000
Clicked Point (Latitude , Longitude ): 33 .13324 , -117 .19614 Time : 2019 -11 -13 10 :30 :07 -0800

15 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT D
FORM 3: VERTICAL SUSCEPTIBILITY FIELD SHEET

FORM 3: VERTICAL SUSCEPTIBILITY FIELD SHEET
Circle appropriate nodes/pathway for proposed site.

Form 3 Figure 1. Vertical Susceptibility photographic supplement to be used in conjunction with Form 3 Bed Resistance above.

Sheet 1 of 4)
B - 6
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 < 5% surface material of diameter < 2 mm
B Intermediate to A and C or hardpan of unknown resistance, spatial extent longitudinal and depth), or unknown armoring potential due to surface veneer covering gravel or coarser layer encountered with probe C Gravels/cobbles that are loosely packed or > 25% surface material of diameter < 2 mm
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)
B - 7
X
Form 3 Checklist 2: Grade Control
A Grade control is present with spacing <50 m or 2/Sv m No evidence of failure/ineffectiveness, e.g., no headcutting (> 30 cm), no active mass wasting ( analyst cannot say grade control sufficient if masswasting 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
Form 3 Figure 3. Grade-control (condition) photographic supplement for assessing intermediate beds (16 < d50 < 128 mm) to be used in conjunction with Form 3 Checklist 2.

Sheet 3 of 4)
B - 8
X
Regionally-Calibrated Screening Index Threshold for Incising/Braiding For transitional bed channels (d50 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.

Form 3 Figure 4. Probability of incising/braiding based on logistic regression of Screening Index and d50 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 incision for current Q10, valley slope, and d50; B = Hardpan/d50 indeterminate; and C = >50% probability of incising/braiding for current Q10, valley slope, and d50. d50 ( mm)
From Form 2
Sv*Q100.5 ( m1.5/ s0.5)
From Form 1
Sv*Q100.5 ( m1.5/ s0.5)
50% risk of incising/braiding
from table in Form 3 Figure 3 above
Screening Index Score

A, B, C)
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 Susceptibility based on Vertical Rating: <4.5 = LOW; 4.5 to 7 = MEDIUM; and >7 = HIGH.

Sheet 4 of 4)
B - 9

0.016 n/a (d50 indeterminate) B
Vertical Rating = 6 x 6 x 6 = 6
6B= 6 6B=B=
16 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT E
FORM 4: LATERAL SUSCEPTIBILITY FIELD SHEET

FORM 4: LATERAL SUSCEPTIBILTY FIELD SHEET
Lateral Screening Forms
Circle appropriate nodes/pathway for proposed site
OR use sequence of questions provided in Form 5.

Sheet 1 of 1)
B - 10

17 4909 Murphy Canyon Road, STE 330, San Diego, CA 92123 | P. 619.787.5566 | F. 866.579.6415

ATTACHMENT F
FORM 6: PROBABILITY OF MASS WASTING BANK FAILURE

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
degrees)
from Field)
Bank Height
m)
from Field)
Corresponding Bank Height for
10% Risk of Mass Wasting ( m)
from Form 6 Figure 1 below)
Bank Failure Risk
10% Risk)
10% Risk)
Left Bank
Right Bank
Form 6 Figure 1. Probability Mass Wasting diagram, Bank Angle:Height/% Risk table, and Band Height:Angle schematic.

Sheet 1 of 1)
B - 12
35 deg
25 deg

1.5 m

1.5 m
10% Risk
10% Risk

4.7 m

7.6 m

Attachment 2d
Flow Control Facility Design
E1 E2
E3
POC1 POC2 POC3
Escondido
09/24/1964 07:00:00
Armorlite Drive - Pre-Project Continuous Simulation Model SWMM 5.2 Page 1
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.2 (Build 5.2.1) ------------------------------------------------------------ 1900 Armorlite Drive - Pre-Project Unmitigated

****************
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 ............ 09/24/1964 06:00:00
Ending Date .............. 05/23/2008 22:00:00
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 ...... 124.770 611.120
Evaporation Loss ......... 5.222 25.576
Infiltration Loss ........ 95.242 466.490
Surface Runoff ........... 26.894 131.724
Final Storage ............ 0.000 0.000
Continuity Error (%) ..... -2.073

************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 26.894 8.764
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 26.894 8.764
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 Imperv
Perv Total Total Peak Runoff
Precip Runon Evap Infil Runoff
Runoff Runoff Runoff Runoff Coeff
Subcatchment in in in in in
in in 10^6 gal CFS

------------------------------------------------------------------------------------ ------------------------------------------
E1 611.12 0.00 25.59 466.97 0.00
131.17 131.17 4.38 0.99 0.215
E2 611.12 0.00 25.53 464.77 0.00
133.71 133.71 2.61 0.58 0.219
E3 611.12 0.00 25.60 467.80 0.00
130.23 130.23 1.77 0.40 0.213

Analysis begun on: Mon Aug 7 19:48:52 2023
Analysis ended on: Mon Aug 7 19:49:07 2023
Total elapsed time: 00:00:15
P1 P2
P3
CURVE
POC1
VAULT
Escondido
Armorlite Drive - Post-Project Miitigated Continuous Simulation Model SWMM 5.2 Page 1
EPA STORM WATER MANAGEMENT MODEL - VERSION 5.2 (Build 5.2.1) ------------------------------------------------------------ 1900 Armorlite Drive - Post-Project Miitigated

****************
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 ............ 09/24/1964 06:00:00
Ending Date .............. 05/23/2008 22:00:00
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
************************** --------- -------
Total Precipitation ...... 124.770 611.120
Evaporation Loss ......... 5.332 26.117
Infiltration Loss ........ 96.646 473.369
Surface Runoff ........... 25.213 123.494
Final Storage ............ 0.000 0.000
Continuity Error (%) ..... -1.941

************************** Volume Volume
Flow Routing Continuity acre-feet 10^6 gal
************************** --------- ---------
Dry Weather Inflow ....... 0.000 0.000
Wet Weather Inflow ....... 25.213 8.216
Groundwater Inflow ....... 0.000 0.000
RDII Inflow .............. 0.000 0.000
External Inflow .......... 0.000 0.000
External Outflow ......... 25.211 8.215
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 (%) ..... 0.010

********************************
Highest Flow Instability Indexes
********************************
All links are stable.

*************************
Routing Time Step Summary
*************************
Minimum Time Step : 59.00 sec
Average Time Step : 60.00 sec
Maximum Time Step : 60.00 sec
% of Time in Steady State : 0.00
Average Iterations per Step : 1.00
% of Steps Not Converging : 0.00

***************************
Subcatchment Runoff Summary
***************************

------------------------------------------------------------------------------------ ------------------------------------------
P1 611.12 0.00 26.00 468.20 0.00
129.20 129.20 1.23 0.28 0.211
P2 611.12 0.00 26.07 471.26 0.00
125.79 125.79 1.95 0.44 0.206
P4 611.12 0.00 26.11 472.74 0.00
124.16 124.16 0.30 0.07 0.203
P5 611.12 0.00 25.27 456.74 0.00
143.50 143.50 0.04 0.01 0.235
P3 611.12 0.00 26.17 475.63 0.00
121.00 121.00 4.70 1.05 0.198

******************
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
--------------------------------------------------------------------------------- POC2 OUTFALL 0.00 0.00 0.00 0 00:00 0.00
POC1 OUTFALL 0.00 0.00 0.00 0 00:00 0.00
POC3 OUTFALL 0.00 0.00 0.00 0 00:00 0.00
VAULT STORAGE 0.00 4.31 4.31 802 03:27 4.31

*******************
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

------------------------------------------------------------------------------------ -------------
POC2 OUTFALL 0.07 0.07 10332 11:01 0.303

0.303 0.000
POC1 OUTFALL 0.00 1.06 802 03:27 0

7.87 0.000
POC3 OUTFALL 0.01 0.01 10332 11:01 0.039

0.039 0.000
VAULT STORAGE 1.77 1.77 10332 11:01 7.87

7.87 0.011

*********************
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

------------------------------------------------------------------------------------ --------------
VAULT 0.013 0 0 0 14.446 96 802
03:27 1.06

***********************
Outfall Loading Summary
***********************

----------------------------------------------------------- Flow Avg Max Total
Freq Flow Flow Volume
Outfall Node Pcnt CFS CFS 10^6 gal
----------------------------------------------------------- POC2 0.40 0.01 0.07 0.303
POC1 1.17 0.07 1.06 7.872
POC3 0.13 0.00 0.01 0.039
----------------------------------------------------------- System 0.57 0.07 1.11 8.215

********************
Link Flow Summary
********************

----------------------------------------------------------------------------- Maximum Time of Max Maximum Max/ Max/
|Flow| Occurrence |Veloc| Full Full
Link Type CFS days hr:min ft/sec Flow Depth
----------------------------------------------------------------------------- CURVE DUMMY 1.06 802 03:27

*************************
Conduit Surcharge Summary
*************************

No conduits were surcharged.

Analysis begun on: Thu Aug 10 09:29:03 2023
Analysis ended on: Thu Aug 10 09:29:21 2023
Total elapsed time: 00:00:18
Page: 1 Discharge Rating Curve
h h
QloworifQmidorif
QlowerslotweirQlowerslotorificeQlowerslottotal
Qupperslot-weir
Qupperslotorifice
QuppertotalQemer
gency h QTOTAL
Invert Elev: 0.00 ft (inches) (feet) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) (feet) (cfs) Diameter: 2.500 in
Num. Of Openings: 1.00 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 Cg: 0.60 0.500 0.042 0.034 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.042 0.034 Diameter: 0.2083333 ft 1.000 0.083 0.047 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.083 0.047

1.500 0.125 0.058 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.125 0.058

2.000 0.167 0.067 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.167 0.067 Invert Elev: ft 2.500 0.208 0.075 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.208 0.075 Diameter: in 3.000 0.250 0.082 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.250 0.082 Num. of Openings: 3.500 0.292 0.089 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.292 0.089 Cg: 0.60 4.000 0.333 0.095 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.333 0.095 Diameter: 0 ft 4.500 0.375 0.101 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.375 0.101

5.000 0.417 0.106 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.417 0.106

5.500 0.458 0.111 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.458 0.111 Invert: ft 6.000 0.500 0.116 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.500 0.116 Base: ft 6.500 0.542 0.121 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.542 0.121 Height: ft 7.000 0.583 0.125 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.583 0.125 Num. of Openings: 7.500 0.625 0.130 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.625 0.130 Cg: 0.6 8.000 0.667 0.134 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.667 0.134 Cw: 3.100 8.500 0.708 0.138 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.708 0.138

9.000 0.750 0.142 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.750 0.142

9.500 0.792 0.146 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.792 0.146 Invert: ft 10.000 0.833 0.150 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.833 0.150 Num. of Openings: 10.500 0.875 0.154 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.875 0.154 Base: ft 11.000 0.917 0.157 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.917 0.157 Height: ft 11.500 0.958 0.161 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.958 0.161 Cg: 0.6 12.000 1.000 0.164 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.000 0.164 Cw: 3.100 12.500 1.042 0.168 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.042 0.168

13.000 1.083 0.171 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.083 0.171

13.500 1.125 0.174 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.125 0.174 Invert: 4.000 ft 14.000 1.167 0.177 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.167 0.177 L: 1.330 ft 14.500 1.208 0.180 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.208 0.180 Cw: 3.100 15.000 1.250 0.184 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.250 0.184

15.500 1.292 0.187 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.292 0.187

16.000 1.333 0.190 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.333 0.190

16.500 1.375 0.192 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.375 0.192

17.000 1.417 0.195 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.417 0.195

17.500 1.458 0.198 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.458 0.198

18.000 1.500 0.201 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.500 0.201

18.500 1.542 0.204 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.542 0.204

19.000 1.583 0.207 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.583 0.207

19.500 1.625 0.209 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.625 0.209

20.000 1.667 0.212 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.667 0.212

20.500 1.708 0.215 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.708 0.215

21.000 1.750 0.217 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.750 0.217

21.500 1.792 0.220 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.792 0.220

22.000 1.833 0.222 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.833 0.222

22.500 1.875 0.225 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.875 0.225

23.000 1.917 0.227 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.917 0.227

23.500 1.958 0.230 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.958 0.230

24.000 2.000 0.232 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.000 0.232

24.500 2.042 0.235 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.042 0.235

25.000 2.083 0.237 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.083 0.237 Mid Orifice (NOT USED)
Lower Slot (NOT USED)
Upper Slot (NOT USED)
Emergency Weir
Outlet Configuration
Low Orifice
~SWMM INPUT~~CALCULATIONS~
H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 2 - HMP Backup\Attach. 2d - HMP Calcs & Worksheets\SWMM Model\1900.00 DischargeCurves_WeirOrifice.xlsx Page: 2 Discharge Rating Curve

25.500 2.125 0.239 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.125 0.239

26.000 2.167 0.242 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.167 0.242

26.500 2.208 0.244 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.208 0.244

27.000 2.250 0.246 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.250 0.246

27.500 2.292 0.248 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.292 0.248

28.000 2.333 0.251 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.333 0.251

28.500 2.375 0.253 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.375 0.253

29.000 2.417 0.255 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.417 0.255

29.500 2.458 0.257 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.458 0.257

30.000 2.500 0.260 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.500 0.260

30.500 2.542 0.262 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.542 0.262

31.000 2.583 0.264 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.583 0.264

31.500 2.625 0.266 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.625 0.266

32.000 2.667 0.268 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.667 0.268

32.500 2.708 0.270 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.708 0.270

33.000 2.750 0.272 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.750 0.272

33.500 2.792 0.274 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.792 0.274

34.000 2.833 0.276 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.833 0.276

34.500 2.875 0.278 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.875 0.278

35.000 2.917 0.280 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.917 0.280

35.500 2.958 0.282 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.958 0.282

36.000 3.000 0.284 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.000 0.284

36.500 3.042 0.286 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.042 0.286

37.000 3.083 0.288 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.083 0.288

37.500 3.125 0.290 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.125 0.290

38.000 3.167 0.292 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.167 0.292

38.500 3.208 0.294 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.208 0.294

39.000 3.250 0.296 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.250 0.296

39.500 3.292 0.298 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.292 0.298

40.000 3.333 0.300 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.333 0.300

40.500 3.375 0.302 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.375 0.302

41.000 3.417 0.303 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.417 0.303

41.500 3.458 0.305 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.458 0.305

42.000 3.500 0.307 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.500 0.307

42.500 3.542 0.309 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.542 0.309

43.000 3.583 0.311 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.583 0.311

43.500 3.625 0.313 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.625 0.313

44.000 3.667 0.314 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.667 0.314

44.500 3.708 0.316 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.708 0.316

45.000 3.750 0.318 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.750 0.318

45.500 3.792 0.320 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.792 0.320

46.000 3.833 0.321 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.833 0.321

46.500 3.875 0.323 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.875 0.323

47.000 3.917 0.325 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.917 0.325

47.500 3.958 0.327 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.958 0.327

48.000 4.000 0.328 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 4.000 0.328

48.500 4.042 0.330 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.035 4.042 0.365

49.000 4.083 0.332 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.099 4.083 0.431

49.500 4.125 0.333 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.182 4.125 0.516

50.000 4.167 0.335 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.281 4.167 0.616

50.500 4.208 0.337 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.392 4.208 0.729

51.000 4.250 0.338 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.515 4.250 0.854

51.500 4.292 0.340 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.649 4.292 0.989

52.000 4.333 0.342 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.793 4.333 1.135

52.500 4.375 0.343 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.947 4.375 1.290

53.000 4.417 0.345 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.109 4.417 1.454

53.500 4.458 0.347 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.279 4.458 1.626

54.000 4.500 0.348 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.458 4.500 1.806

54.500 4.542 0.350 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.644 4.542 1.993 H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 2 - HMP Backup\Attach. 2d - HMP Calcs & Worksheets\SWMM Model\1900.00 DischargeCurves_WeirOrifice.xlsx Page: 3 Discharge Rating Curve

55.000 4.583 0.351 0.000 0.000 0.000 0.000 0.000 0.000 0.000 1.837 4.583 2.188

55.500 4.625 0.353 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.037 4.625 2.390

56.000 4.667 0.355 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.244 4.667 2.599

56.500 4.708 0.356 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.458 4.708 2.814

57.000 4.750 0.358 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.678 4.750 3.036

57.500 4.792 0.359 0.000 0.000 0.000 0.000 0.000 0.000 0.000 2.904 4.792 3.263

58.000 4.833 0.361 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.136 4.833 3.497

58.500 4.875 0.362 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.375 4.875 3.737

59.000 4.917 0.364 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.619 4.917 3.982

59.500 4.958 0.365 0.000 0.000 0.000 0.000 0.000 0.000 0.000 3.868 4.958 4.234

60.000 5.000 0.367 0.000 0.000 0.000 0.000 0.000 0.000 0.000 4.123 5.000 4.490 H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 2 - HMP Backup\Attach. 2d - HMP Calcs & Worksheets\SWMM Model\1900.00 DischargeCurves_WeirOrifice.xlsx Drawdown calculations have been performed using the storage capacity of the proposed basin, and the standard equation for Orifice shown below.

Based on these calculations:
-Entire BMP will drain in 23.5 hours
-No Vector Control Plan is required since structural BMP will drain in less than 96 hrs.

Drawdown calculation
Equation 17.83 of Civil Engineering Reference Manual 15th edition Where:

At: Surface Area of Vault (sq ft.)
Z1: Water Elevation of full tank (ft)
Z2: Water Elevation of empty tank (0 ft)
Cd:Discharge Coefficient
Ao: Area of Orifice (sq. ft.)
g: Gravity (32.2 ft/s^2)
Vault Height
(in)
Vault Height
(ft)
Storage
Area (Sq.
ft.)
Max Suface Storage
Volume (Cu.ft.)
54 4.50 3350 15075
Low Orifice
Diameter (in) 2.50
# of orifices 1
coefficient (cg) 0.614
Ao (sq. ft.) 0.0340885
Drawdown time
(hr) 23.505

DRAWDOWN CALCULATIONS

EQUATIONS
Vault Storage
Drawdown time
(sec) 84617.920
Drawdown time
() =
2 (

−
)
2
Peak Flow Frequency Summary
Return Period Pre-project Qpeak
(cfs)
Post-project - Mitigated Q
(cfs)
LF = 0.3xQ2 0.161 0.057
2-year 0.537 0.189
5-year 0.692 0.251
10-year 0.767 0.296
H:\1900\1900.00 - Cross Real Estate - 225 Las Posas\Engineering\Reports\Water Quality\Attachment 2 - HMP Backup\Attach. 2d - HMP Calcs & Worksheets\SWMM Model\1900.00 Post Processing POC1.xlsx POC 1

0.000

0.200

0.400

0.600

0.800

1.000

1.200
0 1 2 3 4 5 6 7 8 9 10
Peak Flow in cfs
Return Period in Years
Peak Flow Frequency Curves
Pre-project Qpeak
Post-project Mitigated Qpeak
POC 1
Low-flow Threshold: 30%

0.3xQ2 (Pre): 0.161 cfs
Q10 (Pre): 0.767 cfs
Ordinate #: 100
Incremental Q (Pre): 0.00606 cfs
Total Hourly Data: 382743 hours The proposed BMP: PASSED Interval Pre-project Flow
(cfs) Pre-project Hours
Pre-project %
Time Exceeding
Post-project
Hours
Post-project %
Time Exceeding Percentage Pass/Fail
0 0.161 363 9.48E-04 385 1.01E-03 106% Pass
1 0.167 346 9.04E-04 343 8.96E-04 99% Pass
2 0.173 329 8.60E-04 308 8.05E-04 94% Pass
3 0.179 309 8.07E-04 272 7.11E-04 88% Pass
4 0.185 292 7.63E-04 244 6.38E-04 84% Pass
5 0.192 271 7.08E-04 222 5.80E-04 82% Pass
6 0.198 251 6.56E-04 201 5.25E-04 80% Pass
7 0.204 233 6.09E-04 191 4.99E-04 82% Pass
8 0.210 226 5.90E-04 166 4.34E-04 73% Pass
9 0.216 218 5.70E-04 157 4.10E-04 72% Pass
10 0.222 211 5.51E-04 141 3.68E-04 67% Pass
11 0.228 201 5.25E-04 133 3.47E-04 66% Pass
12 0.234 193 5.04E-04 124 3.24E-04 64% Pass
13 0.240 185 4.83E-04 106 2.77E-04 57% Pass
14 0.246 176 4.60E-04 93 2.43E-04 53% Pass
15 0.252 172 4.49E-04 84 2.19E-04 49% Pass
16 0.258 162 4.23E-04 74 1.93E-04 46% Pass
17 0.264 154 4.02E-04 71 1.86E-04 46% Pass
18 0.270 148 3.87E-04 64 1.67E-04 43% Pass
19 0.276 142 3.71E-04 58 1.52E-04 41% Pass
20 0.282 136 3.55E-04 51 1.33E-04 38% Pass
21 0.289 131 3.42E-04 45 1.18E-04 34% Pass
22 0.295 127 3.32E-04 41 1.07E-04 32% Pass
23 0.301 121 3.16E-04 36 9.41E-05 30% Pass
24 0.307 114 2.98E-04 36 9.41E-05 32% Pass
25 0.313 104 2.72E-04 31 8.10E-05 30% Pass
26 0.319 99 2.59E-04 28 7.32E-05 28% Pass
27 0.325 93 2.43E-04 23 6.01E-05 25% Pass
28 0.331 93 2.43E-04 19 4.96E-05 20% Pass
29 0.337 92 2.40E-04 18 4.70E-05 20% Pass
30 0.343 91 2.38E-04 17 4.44E-05 19% Pass
31 0.349 89 2.33E-04 17 4.44E-05 19% Pass
32 0.355 85 2.22E-04 17 4.44E-05 20% Pass
33 0.361 83 2.17E-04 17 4.44E-05 20% Pass
34 0.367 80 2.09E-04 17 4.44E-05 21% Pass
35 0.373 77 2.01E-04 17 4.44E-05 22% Pass
36 0.379 75 1.96E-04 17 4.44E-05 23% Pass
37 0.386 72 1.88E-04 16 4.18E-05 22% Pass
38 0.392 71 1.86E-04 16 4.18E-05 23% Pass
39 0.398 69 1.80E-04 15 3.92E-05 22% Pass
40 0.404 68 1.78E-04 15 3.92E-05 22% Pass
41 0.410 65 1.70E-04 15 3.92E-05 23% Pass
42 0.416 62 1.62E-04 15 3.92E-05 24% Pass
43 0.422 58 1.52E-04 15 3.92E-05 26% Pass
44 0.428 55 1.44E-04 15 3.92E-05 27% Pass
45 0.434 55 1.44E-04 14 3.66E-05 25% Pass
46 0.440 54 1.41E-04 13 3.40E-05 24% Pass
47 0.446 52 1.36E-04 13 3.40E-05 25% Pass
48 0.452 50 1.31E-04 12 3.14E-05 24% Pass
49 0.458 49 1.28E-04 10 2.61E-05 20% Pass
50 0.464 46 1.20E-04 10 2.61E-05 22% Pass
51 0.470 46 1.20E-04 10 2.61E-05 22% Pass
52 0.476 45 1.18E-04 9 2.35E-05 20% Pass
53 0.483 43 1.12E-04 8 2.09E-05 19% Pass
54 0.489 42 1.10E-04 8 2.09E-05 19% Pass
Flow Duration Curve Data
POC 1
Interval Pre-project Flow
(cfs) Pre-project Hours
Pre-project %
Time Exceeding
Post-project
Hours
Post-project %
Time Exceeding Percentage Pass/Fail
55 0.495 39 1.02E-04 7 1.83E-05 18% Pass
56 0.501 38 9.93E-05 7 1.83E-05 18% Pass
57 0.507 37 9.67E-05 7 1.83E-05 19% Pass
58 0.513 36 9.41E-05 7 1.83E-05 19% Pass
59 0.519 35 9.14E-05 7 1.83E-05 20% Pass
60 0.525 35 9.14E-05 6 1.57E-05 17% Pass
61 0.531 35 9.14E-05 5 1.31E-05 14% Pass
62 0.537 34 8.88E-05 5 1.31E-05 15% Pass
63 0.543 33 8.62E-05 5 1.31E-05 15% Pass
64 0.549 30 7.84E-05 5 1.31E-05 17% Pass
65 0.555 28 7.32E-05 5 1.31E-05 18% Pass
66 0.561 27 7.05E-05 5 1.31E-05 19% Pass
67 0.567 26 6.79E-05 5 1.31E-05 19% Pass
68 0.573 24 6.27E-05 5 1.31E-05 21% Pass
69 0.580 23 6.01E-05 5 1.31E-05 22% Pass
70 0.586 23 6.01E-05 5 1.31E-05 22% Pass
71 0.592 22 5.75E-05 4 1.05E-05 18% Pass
72 0.598 22 5.75E-05 4 1.05E-05 18% Pass
73 0.604 21 5.49E-05 4 1.05E-05 19% Pass
74 0.610 19 4.96E-05 4 1.05E-05 21% Pass
75 0.616 19 4.96E-05 3 7.84E-06 16% Pass
76 0.622 19 4.96E-05 3 7.84E-06 16% Pass
77 0.628 19 4.96E-05 3 7.84E-06 16% Pass
78 0.634 19 4.96E-05 3 7.84E-06 16% Pass
79 0.640 18 4.70E-05 3 7.84E-06 17% Pass
80 0.646 17 4.44E-05 3 7.84E-06 18% Pass
81 0.652 17 4.44E-05 3 7.84E-06 18% Pass
82 0.658 17 4.44E-05 3 7.84E-06 18% Pass
83 0.664 14 3.66E-05 3 7.84E-06 21% Pass
84 0.670 13 3.40E-05 3 7.84E-06 23% Pass
85 0.677 12 3.14E-05 3 7.84E-06 25% Pass
86 0.683 12 3.14E-05 3 7.84E-06 25% Pass
87 0.689 11 2.87E-05 3 7.84E-06 27% Pass
88 0.695 9 2.35E-05 3 7.84E-06 33% Pass
89 0.701 8 2.09E-05 3 7.84E-06 38% Pass
90 0.707 7 1.83E-05 3 7.84E-06 43% Pass
91 0.713 7 1.83E-05 3 7.84E-06 43% Pass
92 0.719 7 1.83E-05 3 7.84E-06 43% Pass
93 0.725 7 1.83E-05 2 5.23E-06 29% Pass
94 0.731 7 1.83E-05 2 5.23E-06 29% Pass
95 0.737 6 1.57E-05 2 5.23E-06 33% Pass
96 0.743 6 1.57E-05 2 5.23E-06 33% Pass
97 0.749 6 1.57E-05 2 5.23E-06 33% Pass
98 0.755 6 1.57E-05 2 5.23E-06 33% Pass
99 0.761 6 1.57E-05 2 5.23E-06 33% Pass
100 0.767 5 1.31E-05 2 5.23E-06 40% Pass
POC 1

0.000

0.100

0.200

0.300

0.400

0.500

0.600

0.700

0.800

0.900

1.0E-06 1.0E-05 1.0E-04 1.0E-03 1.0E-02
Flow (cfs)
% Time Exceeding
Flow Duration Curve
[Pre vs. Post (Mitigated)]
Pre-project Q
Post-project (Mitigated) Q
POC 1
City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
ATTACHMENT 3
Structural BMP Maintenance Information
This is the cover sheet for Attachment 3.

Indicate which Items are Included behind this cover sheet:

Attachment
Sequence
Contents Checklist
Attachment 3a Structural BMP Maintenance Thresholds
and Actions (Required)
Included
See Structural BMP Maintenance
Information Checklist on the back of this
Attachment cover sheet.

Attachment 3b Draft Maintenance Agreement (when
applicable)
Included
Not Applicable

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
Use this checklist to ensure the required information has been included in the Structural BMP Maintenance Information Attachment:
Preliminary Design / Planning / CEQA level submittal:

Attachment 3a must identify:
Typical maintenance indicators and actions for proposed structural BMP(s) based on Section 7.7 of the BMP Design Manual
Attachment 3b is not required for preliminary design / planning / CEQA level submittal. Final Design level submittal:

Attachment 3a must identify:
Specific maintenance indicators and actions for proposed structural BMP(s). This shall be based on Section 7.7 of the BMP Design Manual and enhanced to reflect actual proposed components of the structural BMP(s)
How to access the structural BMP(s) to inspect and perform maintenance Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds)
Manufacturer and part number for proprietary parts of structural BMP(s) when applicable
Maintenance thresholds specific to the structural BMP(s), with a location-specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP)
Recommended equipment to perform maintenance
When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management
Attachment 3b: For private entity operation and maintenance, Attachment 3b shall include a draft maintenance agreement in the local jurisdiction's standard format (PDP applicant to contact the [City Engineer] to obtain the current maintenance agreement forms).

I RD S FS W

City of San Marcos PDP SWQMP Template Date: March 15, 2016 PDP SWQMP Preparation Date: 10/23/24
ATTACHMENT 4
Copy of Plan Sheets Showing Permanent Storm Water BMPs
This is the cover sheet for Attachment 4.

Use this checklist to ensure the required information has been included on the plans:

The plans must identify:
Structural BMP(s) with ID numbers matching Form I-6 Summary of PDP Structural BMPs The grading and drainage design shown on the plans must be consistent with the delineation of DMAs shown on the DMA exhibit
Details and specifications for construction of structural BMP(s) Signage indicating the location and boundary of structural BMP(s) as required by the [City Engineer] How to access the structural BMP(s) to inspect and perform maintenance Features that are provided to facilitate inspection (e.g., observation ports, cleanouts, silt posts, or other features that allow the inspector to view necessary components of the structural BMP and compare to maintenance thresholds)
Manufacturer and part number for proprietary parts of structural BMP(s) when applicable Maintenance thresholds specific to the structural BMP(s), with a location-specific frame of reference (e.g., level of accumulated materials that triggers removal of the materials, to be identified based on viewing marks on silt posts or measured with a survey rod with respect to a fixed benchmark within the BMP)
Recommended equipment to perform maintenance
When applicable, necessary special training or certification requirements for inspection and maintenance personnel such as confined space entry or hazardous waste management Include landscaping plan sheets showing vegetation requirements for vegetated structural BMP(s) All BMPs must be fully dimensioned on the plans
When proprietary BMPs are used, site-specific cross section with outflow, inflow, and model number shall be provided. Photocopies of general brochures are not acceptable.

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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633
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MH MH MH MH MH MH MH
10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

MH MH MHMH MH MH MH MH
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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

MH MH MH MH MH MH MH
10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

MH MH MHMH MH MH MH MH
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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

MH MH MHMH MH MH MH MH MH MHMH MH
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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633
10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

MH MH MH MH MHMH MH MH MH MH MH MH MHMH MH
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10731 Treena Street, San Diego, CA 92131
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MH MH MH
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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633
℄

MH MH MH MH MHMH MH MH MH MH MH MH MH MH MHMH MH MH
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10731 Treena Street, San Diego, CA 92131
Tel 858.751.0633

San Marcos City CouncilJune 24, 2025

San Marcos City Council
June 24, 2025