HomeMy WebLinkAboutItem 6-WQMP - Preliminary_4th Submittal_2022-01-03- 1 -
Project Specific Water Quality Management Plan
A Template for Projects located within the Santa Ana Watershed Region of Riverside County
Project Title: 18 acre site at Mission Trail TTM 38378
Development No: Tentative Tract 38378
Design Review/Case No: PWQMP-2022-0005, Planning App#:2022-03 (Design Review#: 2022-02).
Original Date Prepared: March 4, 2022
Revision Date(s):
Prepared for Compliance with
Regional Board Order No. R8-2010-0033
Contact Information:
Prepared for: The Development at
Mission Trails - Lake Elsinore, LLC
1020 2nd Street
Encinitas, CA 92024
Brett Crowder, Project Manager
(949) 632-3122
Prepared by: Wilson Mikami Corporation
9 Corporate Park, Suite 100
Irvine, CA 92606
Scott M. Wilson, PE, PLS, Principal
(949) 679-0090
Preliminary
Final
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A Brief Introduction
This Project-Specific WQMP Template for the Santa Ana Region has been prepared to help guide you in
documenting compliance for your project. Because this document has been designed to specifically
document compliance, you will need to utilize the WQMP Guidance Document as your “how-to” manual
to help guide you through this process. Both the Template and Guidance Document go hand-in-hand, and
will help facilitate a well prepared Project-Specific WQMP. Below is a flowchart for the layout of this
Template that will provide the steps required to document compliance.
Section A
Project and Site Information
Section B
Optimize Site Utilization
Section C
Delineate Drainage Management Areas (DMAs)
Section G
Source Control BMPs
Section I
Operation, Maintenance, and Funding
Section F
Hydromodification
Section E
Alternative Compliance
Section D
Implement LID BMPs
Section H
Construction Plan Checklist
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OWNER’S CERTIFICATION
This Project-Specific Water Quality Management Plan (WQMP) has been prepared for The Development at Mission
Trails - Lake Elsinore, LLC by Wilson Mikami Corporation for The 18 acre site at Mission Trail TTM 38378 project.
This WQMP is intended to comply with the requirements of City of Lake Elsinore Grading Ordinance which includes
the requirement for the preparation and implementation of a Project-Specific WQMP.
The undersigned, while owning the property/project described in the preceding paragraph, shall be responsible for
the implementation and funding of this WQMP and will ensure that this WQMP is amended as appropriate to reflect
up-to-date conditions on the site. In addition, the property owner accepts responsibility for interim operation and
maintenance of Stormwater BMPs until such time as this responsibility is formally transferred to a subsequent
owner. This WQMP will be reviewed with the facility operator, facility supervisors, employees, tenants, maintenance
and service contractors, or any other party (or parties) having responsibility for implementing portions of this
WQMP. At least one copy of this WQMP will be maintained at the project site or project office in perpetuity. The
undersigned is authorized to certify and to approve implementation of this WQMP. The undersigned is aware that
implementation of this WQMP is enforceable under City of Lake Elsinore Water Quality Ordinance (Municipal Code
Chapter 14.08).
"I, the undersigned, certify under penalty of law that the provisions of this WQMP have been reviewed and accepted
and that the WQMP will be transferred to future successors in interest."
Owner’s Signature Date
Owner’s Printed Name Owner’s Title/Position
PREPARER’S CERTIFICATION
“The selection, sizing and design of stormwater treatment and other stormwater quality and quantity control
measures in this plan meet the requirements of Regional Water Quality Control Board Order No. R8-2010-0033 and
any subsequent amendments thereto.”
Preparer’s Signature Date
Scott M. Wilson Principal
Preparer’s Printed Name Preparer’s Title/Position
Preparer’s Licensure: RCE 49884
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Table of Contents
Section A: Project and Site Information........................................................................................................ 6
A.1 Maps and Site Plans ............................................................................................................................ 6
A.2 Identify Receiving Waters ................................................................................................................... 7
A.3 Additional Permits/Approvals required for the Project: .................................................................... 7
Section B: Optimize Site Utilization (LID Principles) ..................................................................................... 8
Section C: Delineate Drainage Management Areas (DMAs) ......................................................................... 9
Section D: Implement LID BMPs ................................................................................................................. 10
D.1 Infiltration Applicability .................................................................................................................... 10
D.2 Harvest and Use Assessment ............................................................................................................ 11
D.3 Bioretention and Biotreatment Assessment .................................................................................... 13
D.4 Feasibility Assessment Summaries ................................................................................................... 14
D.5 LID BMP Sizing .................................................................................................................................. 15
Section E: Alternative Compliance (LID Waiver Program) .......................................................................... 16
E.1 Identify Pollutants of Concern .......................................................................................................... 17
E.2 Stormwater Credits ........................................................................................................................... 18
E.3 Sizing Criteria ..................................................................................................................................... 18
E.4 Treatment Control BMP Selection .................................................................................................... 19
Section F: Hydromodification ..................................................................................................................... 20
F.1 Hydrologic Conditions of Concern (HCOC) Analysis .......................................................................... 20
F.2 HCOC Mitigation ................................................................................................................................ 21
Section G: Source Control BMPs ................................................................................................................. 22
Section H: Construction Plan Checklist ....................................................................................................... 25
Section I: Operation, Maintenance and Funding ........................................................................................ 26
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List of Tables
Table A.1 Identification of Receiving Waters ................................................................................................ 7
Table A.2 Other Applicable Permits .............................................................................................................. 7
Table C.1 DMA Classifications ....................................................................................................................... 9
Table C.2 Type ‘A’, Self-Treating Areas ......................................................................................................... 9
Table C.3 Type ‘B’, Self-Retaining Areas ....................................................................................................... 9
Table C.4 Type ‘C’, Areas that Drain to Self-Retaining Areas ........................................................................ 9
Table C.5 Type ‘D’, Areas Draining to BMPs ............................................................................................... 10
Table D.1 Infiltration Feasibility .................................................................................................................. 10
Table D.2 LID Prioritization Summary Matrix ............................................................................................. 14
Table D.3 DCV Calculations for LID BMPs ...................................................... Error! Bookmark not defined.
Table E.1 Potential Pollutants by Land Use Type ........................................................................................ 17
Table E.2 Water Quality Credits .................................................................................................................. 18
Table E.3 Treatment Control BMP Sizing ....................................................... Error! Bookmark not defined.
Table E.4 Treatment Control BMP Selection .............................................................................................. 19
Table F.1 Hydrologic Conditions of Concern Summary .............................................................................. 20
Table G.1 Permanent and Operational Source Control Measures ............................................................. 22
Table H.1 Construction Plan Cross-reference ............................................................................................. 25
List of Appendices
Appendix 1: Maps and Site Plans ................................................................................................................ 27
Appendix 2: Construction Plans .................................................................................................................. 28
Appendix 3: Soils Information ..................................................................................................................... 29
Appendix 4: Historical Site Conditions ........................................................................................................ 30
Appendix 5: LID Infeasibility ........................................................................................................................ 31
Appendix 6: BMP Design Details ................................................................................................................. 33
Appendix 7: Hydromodification .................................................................................................................. 35
Appendix 8: Source Control ........................................................................................................................ 36
Appendix 9: O&M ....................................................................................................................................... 37
Appendix 10: Educational Materials ....................................................................................................... - 38 -
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Section A: Project and Site Information
PROJECT INFORMATION
Type of Project: Mixed Use: Single Family Residential
Planning Area: East Lake Specific Plan
Community Name: East Lake Specific Plan
Development Name: Tentative Tract 38378, 18 Acre Site at Mission Trail
PROJECT LOCATION
Latitude & Longitude (DMS): 33°38'3"N, 117°17'28"W (33.634167, 117.291111)
Project Watershed and Sub-Watershed: Santa Ana River Watershed and San Jacinto River Sub-Watershed
APN(s): 370-050-019, 020 and 032
Map Book and Page No.: Map Book 543, Pages 259
PROJECT CHARACTERISTICS
Proposed or Potential Land Use(s) Singled Family Residential
Proposed or Potential SIC Code(s) 1522
Area of Impervious Project Footprint (SF) 788,192 SF
Total Area of proposed Impervious Surfaces within the Project Limits (SF)/or Replacement 507,769 SF
Does the project consist of offsite road improvements? Y N
Does the project propose to construct unpaved roads? Y N
Is the project part of a larger common plan of development (phased project)? Y N
EXISTING SITE CHARACTERISTICS
Total area of existing Impervious Surfaces within the project limits (SF) 0
Is the project located within any MSHCP Criteria Cell? Y N
If so, identify the Cell number:
Are there any natural hydrologic features on the project site? Y N
Is a Geotechnical Report attached? Y N
If no Geotech. Report, list the NRCS soils type(s) present on the site (A, B, C and/or D): See Appendix 3
What is the Water Quality Design Storm Depth for the project? 0.80 in
A.1 Maps and Site Plans
When completing your Project-Specific WQMP, include a map of the local vicinity and existing site. In
addition, include all grading, drainage, landscape/plant palette and other pertinent construction plans in
Appendix 2. At a minimum, your WQMP Site Plan should include the following:
• Drainage Management Areas
• Proposed Structural BMPs
• Drainage Path
• Drainage Infrastructure, Inlets, Overflows
• Source Control BMPs
• Buildings, Roof Lines, Downspouts
• Impervious Surfaces
• Standard Labeling
Use your discretion on whether or not you may need to create multiple sheets or can appropriately
accommodate these features on one or two sheets. Keep in mind that the Co-Permittee plan reviewer
must be able to easily analyze your project utilizing this template and its associated site plans and maps.
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The project site currently is a vacant site with little ground cover and no current uses for the site. The
proposed project is duplex condominium homes with a total on-site project area of 9.72 acres. The total
impervious area is 6.97 acres and pervious area is 2.75 acres.
A.2 Identify Receiving Waters
Using Table A.1 below, list in order of upstream to downstream, the receiving waters that the project site
is tributary to. Continue to fill each row with the Receiving Water’s 303(d) listed impairments (if any),
designated beneficial uses, and proximity, if any, to a RARE beneficial use. Include a map of the receiving
waters in Appendix 1.
Table A.1 Identification of Receiving Waters
Receiving Waters EPA Approved 303(d) List
Impairments
Designated
Beneficial Uses
Proximity to RARE
Beneficial Use
Lake Elsinore Nutrients
Organic Enrichment/Low Dissolved Oxygen
PCBs (Polychlorinated biphenyls)
Unknown Toxicity
MUN, AGR, GWR,
REC1, REC2, COLD,
WILD
N/A
A.3 Additional Permits/Approvals required for the Project:
Table A.2 Other Applicable Permits
Agency Permit Required
State Department of Fish and Game, 1602 Streambed Alteration Agreement Y N
State Water Resources Control Board, Clean Water Act (CWA) Section 401 Water Quality Cert. Y N
US Army Corps of Engineers, CWA Section 404 Permit Y N
US Fish and Wildlife, Endangered Species Act Section 7 Biological Opinion Y N
Statewide Construction General Permit Coverage Y N
Statewide Industrial General Permit Coverage Y N
Western Riverside MSHCP Consistency Approval (e.g., JPR, DBESP) Y N
Other (please list in the space below as required)
City Building and Grading Permit Y N
If yes is answered to any of the questions above, the Co-Permittee may require proof of
approval/coverage from those agencies as applicable including documentation of any associated
requirements that may affect this Project-Specific WQMP.
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Section B: Optimize Site Utilization (LID Principles)
Site Optimization
The following questions are based upon Section 3.2 of the WQMP Guidance Document. Review of the
WQMP Guidance Document will help you determine how best to optimize your site and subsequently
identify opportunities and/or constraints, and document compliance.
Did you identify and preserve existing drainage patterns? If so, how? If not, why?
The site layout conforms to natural landform, which drains from east to west direction.
Did you identify and protect existing vegetation? If so, how? If not, why?
N/A, no significant trees and other natural vegetation to preserve.
Did you identify and preserve natural infiltration capacity? If so, how? If not, why?
N/A, Infiltration BMPs are not to be used for this site per Section D.1
Did you identify and minimize impervious area? If so, how? If not, why?
Landscape areas are proposed where possible to minimize impervious areas.
Did you identify and disperse runoff to adjacent pervious areas? If so, how? If not, why?
Stormwater is proposed to be intercepted in inlets in designated landscaped areas and discharged into
bioretention/biofiltration treatment Filterra Units and then discharged into the existing four corner storm
drain system which ultimately discharges directly to Lake Elsinore back basin.
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Section C: Delineate Drainage Management Areas
(DMAs)
Table C.1 DMA Classifications
DMA Name or ID Surface Type(s)1 Area (Sq. Ft.) DMA Type
A Roofs, Asphalt, and Landscaping 103,080 Type D
B Roofs, Asphalt, and Landscaping 56,857 Type D
C Roofs, Asphalt, and Landscaping 106,359 Type D
D Roofs, Asphalt, and Landscaping 76,075 Type D
E Roofs, Asphalt, and Landscaping 76,789 Type D
F Roofs, Asphalt, and Landscaping 100,711 Type D
G Roofs, Asphalt, and Landscaping 45,891 Type D
H Roofs, Asphalt, and Landscaping 51,632 Type D
I Roofs, Asphalt, and Landscaping 62,238 Type D
J Roofs, Asphalt, and Landscaping 43,485 Type D
K Asphalt and Landscaping 38,145 Type D
1Reference Table 2-1 in the WQMP Guidance Document to populate this column
Table C.2 Type ‘A’, Self-Treating Areas
DMA Name or ID Area (Sq. Ft.) Stabilization Type Irrigation Type (if any)
N/A
Table C.3 Type ‘B’, Self-Retaining Areas
Self-Retaining Area
Type ‘C’ DMAs that are draining to the Self-Retaining
Area
DMA
Name/
ID
Post-project
surface type
Area
(square
feet)
Storm
Depth
(inches) DMA Name /
ID
[C] from Table C.4 =
Required Retention Depth
(inches)
[A] [B] [C] [D]
N/A [𝐷𝐷]=[𝐵𝐵]+[𝐵𝐵]∙[𝐶𝐶][𝐴𝐴]
Table C.4 Type ‘C’, Areas that Drain to Self-Retaining Areas
DMA Receiving Self-Retaining DMA DMA Name/ ID Area (square feet) Post-project surface type Runoff factor Product
DMA name /ID
Area (square
feet) Ratio
[A] [B] [C] = [A] x [B] [D] [C]/[D]
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Table C.5 Type ‘D’, Areas Draining to BMPs
DMA Name or ID BMP Name or ID
A Bioretention/BioFiltration BMP Filterra Model FTBSV0610
B Bioretention/BioFiltration BMP Filterra Model FTBSV0608
C Bioretention/BioFiltration BMP Filterra Model FTBSV0608
D Bioretention/BioFiltration BMP Filterra Model FTIBC0610-C
E Bioretention/BioFiltration BMP Filterra Model FTIBC 0610-C
F Bioretention/BioFiltration BMP Filterra Model FTBSV0612
G Bioretention/BioFiltration BMP Filterra Model FTBSV0606
H Bioretention/BioFiltration BMP Filterra Model FTBSV0606
I Bioretention/BioFiltration BMP Filterra Model FTBSV0608
J Bioretention/BioFiltration BMP Filterra Model FTBSV0606
K Bioretention/BioFiltration BMP Filterra Model FTBSV0606
Note: More than one drainage management area can drain to a single LID BMP, however, one drainage
management area may not drain to more than one BMP.
Section D: Implement LID BMPs
D.1 Infiltration Applicability
Is there an approved downstream ‘Highest and Best Use’ for stormwater runoff (see discussion in Chapter
2.4.4 of the WQMP Guidance Document for further details)? Y N Lake Elsinore
If yes has been checked, Infiltration BMPs shall not be used for the site. If no, continue working through
this section to implement your LID BMPs. It is recommended that you contact your Co-Permittee to verify
whether or not your project discharges to an approved downstream ‘Highest and Best Use’ feature.
Geotechnical Report
Is this project classified as a small project consistent with the requirements of Chapter 2 of the WQMP
Guidance Document? Y N
Infiltration Feasibility
Table D.1 Infiltration Feasibility
Does the project site… YES NO
…have any DMAs with a seasonal high groundwater mark shallower than 10 feet? X
If Yes, list affected DMAs:
…have any DMAs located within 100 feet of a water supply well? X
If Yes, list affected DMAs:
…have any areas identified by the geotechnical report as posing a public safety risk where infiltration of stormwater
could have a negative impact?
X
If Yes, list affected DMAs:
…have measured in-situ infiltration rates of less than 1.6 inches / hour? Has not been studied yet. X
If Yes, list affected DMAs:
…have significant cut and/or fill conditions that would preclude in-situ testing of infiltration rates at the final
infiltration surface?
X
If Yes, list affected DMAs:
…geotechnical report identify other site-specific factors that would preclude effective and safe infiltration? X
Describe here:
If you answered “Yes” to any of the questions above for any DMA, Infiltration BMPs should not be used
for those DMAs and you should proceed to the assessment for Harvest and Use below.
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D.2 Harvest and Use Assessment (N/A)
Please check what applies:
Reclaimed water will be used for the non-potable water demands for the project.
Downstream water rights may be impacted by Harvest and Use as approved by the Regional
Board (verify with the Copermittee).
The Design Capture Volume will be addressed using Infiltration Only BMPs. In such a case,
Harvest and Use BMPs are still encouraged, but it would not be required if the Design Capture
Volume will be infiltrated or evapotranspired.
If any of the above boxes have been checked, Harvest and Use BMPs need not be assessed for the site. If
neither of the above criteria applies, follow the steps below to assess the feasibility of irrigation use, toilet
use and other non-potable uses (e.g., industrial use).
Irrigation Use Feasibility
Complete the following steps to determine the feasibility of harvesting stormwater runoff for Irrigation
Use BMPs on your site:
Step 1: Identify the total area of irrigated landscape on the site, and the type of landscaping used.
Total Area of Irrigated Landscape: 280,423 SF
Type of Landscaping (Conservation Design or Active Turf): Active Turf
Step 2: Identify the planned total of all impervious areas on the proposed project from which runoff
might be feasibly captured and stored for irrigation use. Depending on the configuration of
buildings and other impervious areas on the site, you may consider the site as a whole, or parts
of the site, to evaluate reasonable scenarios for capturing and storing runoff and directing the
stored runoff to the potential use(s) identified in Step 1 above.
Total Area of Impervious Surfaces: 507,769 SF
Step 3: Cross reference the Design Storm depth for the project site (see Exhibit A of the WQMP
Guidance Document) with the left column of Table 2-3 in Chapter 2 to determine the minimum
area of Effective Irrigated Area per Tributary Impervious Area (EIATIA).
Enter your EIATIA factor: 0.98
Step 4: Multiply the unit value obtained from Step 3 by the total of impervious areas from Step 2 to
develop the minimum irrigated area that would be required.
Minimum required irrigated area: 497,614 SF
Step 5: Determine if harvesting stormwater runoff for irrigation use is feasible for the project by
comparing the total area of irrigated landscape (Step 1) to the minimum required irrigated area
(Step 4).
Minimum required irrigated area (Step 4) Available Irrigated Landscape (Step 1)
497,614 SF 280,423 SF
Conclusion: harvesting stormwater for irrigation use is not feasible.
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Toilet Use Feasibility
Complete the following steps to determine the feasibility of harvesting stormwater runoff for toilet
flushing uses on your site:
Step 1: Identify the projected total number of daily toilet users during the wet season, and account for
any periodic shut downs or other lapses in occupancy:
Projected Number of Daily Toilet Users: 478
Project Type: Single Family Residential
Step 2: Identify the planned total of all impervious areas on the proposed project from which runoff
might be feasibly captured and stored for toilet use. Depending on the configuration of
buildings and other impervious areas on the site, you may consider the site as a whole, or parts
of the site, to evaluate reasonable scenarios for capturing and storing runoff and directing the
stored runoff to the potential use(s) identified in Step 1 above.
Total Area of Impervious Surfaces: 507,769 SF
Step 3: Enter the Design Storm depth for the project site (see Exhibit A) into the left column of Table 2-
1 in Chapter 2 to determine the minimum number or toilet users per tributary impervious acre
(TUTIA).
Enter your TUTIA factor: 131 tu/acre
Step 4: Multiply the unit value obtained from Step 3 by the total of impervious areas from Step 2 to
develop the minimum number of toilet users that would be required.
Minimum number of toilet users: 1,527
Step 5: Determine if harvesting stormwater runoff for toilet flushing use is feasible for the project by
comparing the Number of Daily Toilet Users (Step 1) to the minimum required number of toilet
users (Step 4).
Minimum required Toilet Users (Step 4) Projected number of toilet users (Step 1)
1,527 478
Conclusion: harvesting stormwater for toilet flushing use is not feasible.
Other Non-Potable Use Feasibility (N/A)
Are there other non-potable uses for stormwater runoff on the site (e.g. industrial use)? See Chapter 2 of
the Guidance for further information. If yes, describe below. If no, write N/A.
N/A
Step 1: Identify the projected average daily non-potable demand, in gallons per day, during the wet
season and accounting for any periodic shut downs or other lapses in occupancy or operation.
Average Daily Demand:
Step 2: Identify the planned total of all impervious areas on the proposed project from which runoff
might be feasibly captured and stored for the identified non-potable use. Depending on the
configuration of buildings and other impervious areas on the site, you may consider the site as
a whole, or parts of the site, to evaluate reasonable scenarios for capturing and storing runoff
and directing the stored runoff to the potential use(s) identified in Step 1 above.
Total Area of Impervious Surfaces:
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Step 3: Enter the Design Storm depth for the project site (see Exhibit A) into the left column of Table 2-
3 in Chapter 2 to determine the minimum demand for non-potable uses per tributary
impervious acre.
Enter the factor from Table 2-3:
Step 4: Multiply the unit value obtained from Step 4 by the total of impervious areas from Step 3 to
develop the minimum number of gallons per day of non-potable use that would be required.
Minimum required use:
Step 5: Determine if harvesting stormwater runoff for other non-potable use is feasible for the project
by comparing the Number of Daily Toilet Users (Step 1) to the minimum required number of
toilet users (Step 4).
Minimum required non-potable use (Step 4) Projected average daily use (Step 1)
If Irrigation, Toilet and Other Use feasibility anticipated demands are less than the applicable minimum
values, Harvest and Use BMPs are not required and you should proceed to utilize LID Bioretention and
Biotreatment, unless a site-specific analysis has been completed that demonstrates technical infeasibility
as noted in D.3 below.
D.3 Bioretention and Biotreatment Assessment
Other LID Bioretention and Biotreatment BMPs as described in Chapter 2.4.7 of the WQMP Guidance
Document are feasible on nearly all development sites with sufficient advance planning.
Select one of the following:
LID Bioretention/Biotreatment BMPs will be used for some or all DMAs of the project as noted
below in Section D.4 (note the requirements of Section 3.4.2 in the WQMP Guidance
Document).
A site-specific analysis demonstrating the technical infeasibility of all LID BMPs has been
performed and is included in Appendix 5. If you plan to submit an analysis demonstrating the
technical infeasibility of LID BMPs, request a pre-submittal meeting with the Copermittee to
discuss this option. Proceed to Section E to document your alternative compliance measures.
Note: LID Bioretention BMPs are feasible, however, due to constraints in the depth of the existing outlet
storm drain and the project design as documented in Appendix 5, a Filterra Bioretention/Biofiltration
System BMP will be used for all DMAs of the project. However, the Permittee has not approved the
Filterra Bioretention/Biofiltration System BMP product as a LID BMP so it is considered herein as
Treatment Control, Alternative Compliance.
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D.4 Feasibility Assessment Summaries
From the Infiltration, Harvest and Use, Bioretention and Biotreatment Sections above, complete Table
D.2 below to summarize which LID BMPs are technically feasible, and which are not, based upon the
established hierarchy.
Table D.2 LID Prioritization Summary Matrix
DMA
Name/ID
LID BMP Hierarchy No LID
(Alternative
Compliance) 1. Infiltration 2. Harvest and use 3. Bioretention 4. Biotreatment
A
B
C
D
E
F
G
H
I
J
K
For those DMAs where LID BMPs are not feasible, provide a brief narrative below summarizing why they
are not feasible, include your technical infeasibility criteria in Appendix 5, and proceed to Section E below
to document Alternative Compliance measures for those DMAs. Recall that each proposed DMA must
pass through the LID BMP hierarchy before alternative compliance measures may be considered.
LID Bioretention BMPs are feasible, however, due to constraints in the depth of the existing outlet storm
drain and project design as documented in Appendix 5, a Filterra Bioretention/Biofiltration System BMP
will be used for all DMAs of the project. However, the Permittee has not approved the Filterra
Bioretention/Filtration System BMP product as a LID BMP so it is considered herein as Treatment Control,
Alternative Compliance.
The project discharges to Lake Elsinore which has an approved downstream ‘Highest and Best Use’ for
storm water runoff per the WQMP Guidance documents. As a result, no infiltration BMPs are proposed
for the project.
DMA A-K – A Filterra Bioretention/Biofiltration System BMP Unit will be installed to treat street/hardscape
and landscape runoff within the site prior to discharging the flow off-site. This project discharges to
approved downstream ‘Highest and Best Use’ for stormwater runoff, Lake Elsinore.
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D.5 LID BMP Sizing
Each LID BMP must be designed to ensure that the Design Capture Volume will be addressed by the
selected BMPs. First, calculate the Design Capture Volume for each LID BMP using the VBMP worksheet in
Appendix F of the LID BMP Design Handbook. Second, design the LID BMP to meet the required VBMP using
a method approved by the Copermittee. Utilize the worksheets found in the LID BMP Design Handbook
or consult with your Copermittee to assist you in correctly sizing your LID BMPs. Complete Table D.3 below
to document the Design Capture Volume and the Proposed Volume for each LID BMP. Provide the
completed design procedure sheets for each LID BMP in Appendix 6. You may add additional rows to the
table below as needed.
The project discharges to Lake Elsinore which has an approved downstream ‘Highest and Best Use’ for
storm water runoff per the WQMP Guidance documents. As a result, an infiltration/volume based BMP
is not used. In addition, an Alternative Compliance BMP (Filterra Bioretention/Biofiltration) is proposed
the project. This BMP is flow based BMP sizing.
Table D.3 Calculations for LID BMPs
DMA
Type/ID
DMA
Area
(square
feet)
Post-
Project
Surface
Type
Effective
Impervious
Fraction, If
DMA
Runoff
Factor
DMA
Areas x
Runoff
Factor
[A] [B] [C] [A] x [C]
Design
Rainfall
Intensity
(in/hr)
Design Flow
Rate, QBMP
(cubic feet per
second)
Proposed
Flow Rate
on Plans
(cubic
feet per
second)
[G]
[B], [C] is obtained as described in Section 2.3.1 of the WQMP Guidance Document
[E] is obtained from Exhibit A in the WQMP Guidance Document
[G] is obtained from a design procedure sheet, such as in LID BMP Design Handbook and placed in Appendix 6. The project
discharges to Lake Elsinore which has an approved downstream ‘Highest and Best Use’ for storm water runoff per the WQMP
Guidance documents. As a result, no infiltration LID BMPs are proposed for the project. A flow based BMP is proposed for the
project.
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Section E: Alternative Compliance (LID Waiver Program)
LID BMPs are expected to be feasible on virtually all projects. Where LID BMPs have been demonstrated
to be infeasible as documented in Section D, other Treatment Control BMPs must be used (subject to LID
waiver approval by the Co-permittee). Check one of the following Boxes:
LID Principles and LID BMPs have been incorporated into the site design to fully address all
Drainage Management Areas. No alternative compliance measures are required for this project
and thus this Section is not required to be completed.
- Or -
The following Drainage Management Areas are unable to be addressed using LID BMPs. A site-
specific analysis demonstrating technical infeasibility of LID BMPs has been approved by the
Co-Permittee and included in Appendix 5. Additionally, no downstream regional and/or sub-
regional LID BMPs exist or are available for use by the project. The following alternative
compliance measures on the following pages are being implemented to ensure that any pollutant
loads expected to be discharged by not incorporating LID BMPs, are fully mitigated.
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E.1 Identify Pollutants of Concern
Utilizing Table A.1 from Section A above which noted your project’s receiving waters and their associated
EPA approved 303(d) listed impairments, cross reference this information with that of your selected
Priority Development Project Category in Table E.1 below. If the identified General Pollutant Categories
are the same as those listed for your receiving waters, then these will be your Pollutants of Concern and
the appropriate box or boxes will be checked on the last row. The purpose of this is to document
compliance and to help you appropriately plan for mitigating your Pollutants of Concern in lieu of
implementing LID BMPs.
Table E.1 Potential Pollutants by Land Use Type
Priority Development
Project Categories and/or Project Features (check those that apply)
General Pollutant Categories
Bacterial Indicators Metals Nutrients Pesticides Toxic Organic Compounds Sediments Trash & Debris Oil & Grease
Detached Residential
Development P N P P N P P P
Attached Residential
Development P N P P N P P P(2)
Commercial/Industrial
Development P(3) P P(1) P(1) P(5) P(1) P P
Automotive Repair
Shops N P N N P(4, 5) N P P
Restaurants
(>5,000 ft2) P N N N N N P P
Hillside Development
(>5,000 ft2) P N P P N P P P
Parking Lots
(>5,000 ft2) P(6) P P(1) P(1) P(4) P(1) P P
Retail Gasoline Outlets N P N N P N P P
Project Priority Pollutant(s)
of Concern
P = Potential
N = Not Potential
(1) A potential Pollutant if non-native landscaping exists or is proposed onsite; otherwise not expected
(2) A potential Pollutant if the project includes uncovered parking areas; otherwise not expected
(3) A potential Pollutant is land use involving animal waste
(4) Specifically petroleum hydrocarbons
(5) Specifically solvents
(6) Bacterial indicators are routinely detected in pavement runoff
- 18 -
E.2 Stormwater Credits
Projects that cannot implement LID BMPs but nevertheless implement smart growth principles are
potentially eligible for Stormwater Credits. Utilize Table 3-8 within the WQMP Guidance Document to
identify your Project Category and its associated Water Quality Credit. If not applicable, write N/A.
Table E.2 Water Quality Credits
Qualifying Project Categories Credit Percentage2
N/A
Total Credit Percentage1
1Cannot Exceed 50%
2Obtain corresponding data from Table 3-8 in the WQMP Guidance Document
E.3 Sizing Criteria
After you appropriately considered Stormwater Credits for your project, utilize Table E.3 below to
appropriately size them to the DCV, or Design Flow Rate, as applicable. Please reference Chapter 3.5.2 of
the WQMP Guidance Document for further information.
Table E.3 Treatment Control BMP Sizing
DMA
Type/ID
DMA
Area
(square
feet)
Post-
Project
Surface
Type
Effective
Impervious
Fraction, If
DMA
Runoff
Factor
DMA
Areas x
Runoff
Factor
Filterra Bioretention/Biofiltration
System
[A] [B] [C] [A] x [C]
A 103,080 Mixed 0.704 0.50 51,301
Design
Storm
Depth
(in)
Minimum
Design Flow
Rate (cubic feet
or cfs)
Proposed
Flow Rate
on Plans
(cubic
feet per
second)
[G]
B 56,857 Mixed 0.769 0.56 32,075
C 106,359 Mixed 0.585 0.40 42,291
D 76,075 Mixed 0.814 0.62 46,860
E 76,789 Mixed 0.807 0.61 46,655
F 100,711 Mixed 0.763 0.56 56,115
G 45,891 Mixed 0.750 0.54 24,952
H 51,632 Mixed 0.735 0.53 27,272
I 62,238 Mixed 0.724 0.52 32,185
J 43,485 Mixed 0.778 0.57 24,964
K 38,145 Mixed 0.875 0.69 26,505
761,262 411175 0.80 1.89 2.0
[B], [C] is obtained as described in Section 2.3.1 from the WQMP Guidance Document
[E] is obtained from Exhibit A in the WQMP Guidance Document
[G] is for Flow-Based Treatment Control BMPs [G] = 43,560, for Volume-Based Control Treatment BMPs, [G] = 12
[H] is from the Total Credit Percentage as Calculated from Table E.2 above
[I] as obtained from a design procedure sheet from the BMP manufacturer and should be included in Appendix 6
- 19 -
E.4 Treatment Control BMP Selection
Treatment Control BMPs typically provide proprietary treatment mechanisms to treat potential pollutants
in runoff, but do not sustain significant biological processes. Treatment Control BMPs must have a removal
efficiency of a medium or high effectiveness as quantified below:
• High: equal to or greater than 80% removal efficiency
• Medium: between 40% and 80% removal efficiency
Such removal efficiency documentation (e.g., studies, reports, etc.) as further discussed in Chapter 3.5.2
of the WQMP Guidance Document, must be included in Appendix 6. In addition, ensure that proposed
Treatment Control BMPs are properly identified on the WQMP Site Plan in Appendix 1.
Table E.4 Treatment Control BMP Selection
Selected Treatment Control BMP
Name or ID1
Priority Pollutant(s) of
Concern to Mitigate2
Removal Efficiency
Percentage3
Filterra Units (DMA A-K)
Bioretention/Biofiltration BMP
(See Filterra Equivalence Analysis in
Appendix 6)
Bacterial Indicators,
Nutrients, Pesticides,
Sediments, Trash and Debris,
Oil and Grease
High removal efficiency
1 Treatment Control BMPs must not be constructed within Receiving Waters. In addition, a proposed Treatment Control BMP may be
listed more than once if they possess more than one qualifying pollutant removal efficiency.
2 Cross Reference Table E.1 above to populate this column.
3 As documented in a Co-Permittee Approved Study and provided in Appendix 6.
- 20 -
Section F: Hydromodification
F.1 Hydrologic Conditions of Concern (HCOC) Analysis
Once you have determined that the LID design is adequate to address water quality requirements, you
will need to assess if the proposed LID Design may still create a HCOC. Review Chapters 2 and 3 (including
Figure 3-7) of the WQMP Guidance Document to determine if your project must mitigate for
Hydromodification impacts. If your project meets one of the following criteria which will be indicated by
the check boxes below, you do not need to address Hydromodification at this time. However, if the
project does not qualify for Exemptions 1, 2 or 3, then additional measures must be added to the design
to comply with HCOC criteria. This is discussed in further detail below in Section F.2.
HCOC EXEMPTION 1: The Priority Development Project disturbs less than one acre. The Copermittee
has the discretion to require a Project-Specific WQMP to address HCOCs on projects less than one
acre on a case by case basis. The disturbed area calculation should include all disturbances associated
with larger common plans of development.
Does the project qualify for this HCOC Exemption? Y N
If Yes, HCOC criteria do not apply.
HCOC EXEMPTION 2: The volume and time of concentration1 of storm water runoff for the post-
development condition is not significantly different from the pre-development condition for a 2-year
return frequency storm (a difference of 5% or less is considered insignificant) using one of the
following methods to calculate:
• Riverside County Hydrology Manual
• Technical Release 55 (TR-55): Urban Hydrology for Small Watersheds (NRCS 1986), or
derivatives thereof, such as the Santa Barbara Urban Hydrograph Method
• Other methods acceptable to the Co-Permittee
Does the project qualify for this HCOC Exemption? Y N
If Yes, report results in Table F.1 below and provide your substantiated hydrologic analysis in
Appendix 7.
Table F.1 Hydrologic Conditions of Concern Summary
2 year – 24 hour
Pre-condition Post-condition % Difference
Time of
Concentration
Volume (Cubic Feet)
1 Time of concentration is defined as the time after the beginning of the rainfall when all portions of the drainage basin
are contributing to flow at the outlet.
- 21 -
HCOC EXEMPTION 3: All downstream conveyance channels to an adequate sump (for example,
Prado Dam, Lake Elsinore, Canyon Lake, Santa Ana River, or other lake, reservoir or naturally
erosion resistant feature) that will receive runoff from the project are engineered and regularly
maintained to ensure design flow capacity; no sensitive stream habitat areas will be adversely
affected; or are not identified on the Co-Permittees Hydromodification Sensitivity Maps.
Does the project qualify for this HCOC Exemption? Y N
If Yes, HCOC criteria do not apply and note below which adequate sump applies to this HCOC
qualifier:
Downstream conveyance channels directly into Lake Elsinore which is engineered and regularly
maintained to ensure design flow capacity.
F.2 HCOC Mitigation
If none of the above HCOC Exemption Criteria are applicable, HCOC criteria is considered mitigated if they
meet one of the following conditions:
a. Additional LID BMPS are implemented onsite or offsite to mitigate potential erosion or habitat
impacts as a result of HCOCs. This can be conducted by an evaluation of site-specific conditions
utilizing accepted professional methodologies published by entities such as the California
Stormwater Quality Association (CASQA), the Southern California Coastal Water Research Project
(SCCRWP), or other Co-Permittee approved methodologies for site-specific HCOC analysis.
b. The project is developed consistent with an approved Watershed Action Plan that addresses
HCOC in Receiving Waters.
c. Mimicking the pre-development hydrograph with the post-development hydrograph, for a 2-year
return frequency storm. Generally, the hydrologic conditions of concern are not significant, if the
post-development hydrograph is no more than 10% greater than pre-development hydrograph.
In cases where excess volume cannot be infiltrated or captured and reused, discharge from the
site must be limited to a flow rate no greater than 110% of the pre-development 2-year peak flow.
Be sure to include all pertinent documentation used in your analysis of the items a, b or c in Appendix 7.
- 22 -
Section G: Source Control BMPs
Source control BMPs include permanent, structural features that may be required in your project plans —
such as roofs over and berms around trash and recycling areas — and Operational BMPs, such as regular
sweeping and “housekeeping”, that must be implemented by the site’s occupant or user. The MEP
standard typically requires both types of BMPs. In general, Operational BMPs cannot be substituted for a
feasible and effective permanent BMP. Using the Pollutant Sources/Source Control Checklist in Appendix
8, review the following procedure to specify Source Control BMPs for your site:
1. Identify Pollutant Sources: Review Column 1 in the Pollutant Sources/Source Control Checklist. Check
off the potential sources of Pollutants that apply to your site.
2. Note Locations on Project-Specific WQMP Exhibit: Note the corresponding requirements listed in
Column 2 of the Pollutant Sources/Source Control Checklist. Show the location of each Pollutant
source and each permanent Source Control BMP in your Project-Specific WQMP Exhibit located in
Appendix 1.
3. Prepare a Table and Narrative: Check off the corresponding requirements listed in Column 3 in the
Pollutant Sources/Source Control Checklist. In the left column of Table G.1 below, list each potential
source of runoff Pollutants on your site (from those that you checked in the Pollutant Sources/Source
Control Checklist). In the middle column, list the corresponding permanent, Structural Source Control
BMPs (from Columns 2 and 3 of the Pollutant Sources/Source Control Checklist) used to prevent
Pollutants from entering runoff. Add additional narrative in this column that explains any special
features, materials or methods of construction that will be used to implement these permanent,
Structural Source Control BMPs.
4. Identify Operational Source Control BMPs: To complete your table, refer once again to the Pollutant
Sources/Source Control Checklist. List in the right column of your table the Operational BMPs that
should be implemented as long as the anticipated activities continue at the site. Copermittee
stormwater ordinances require that applicable Source Control BMPs be implemented; the same BMPs
may also be required as a condition of a use permit or other revocable Discretionary Approval for use
of the site.
Table G.1 Permanent and Operational Source Control Measures
Potential Sources of Runoff
pollutants
Permanent Structural Source
Control BMPs
Operational Source Control BMPs
On-site storm drain inlets*
Mark all inlets with the
words “Only Rain Down the
Storm Drain” or similar.
Catch Basin Markers may
be available from the
Riverside County Flood
Control and Water
Conservation District, call
951.955.1200 to verify.
Maintain and periodically repaint or
replace inlet markings.
Provide stormwater pollution prevention
information to new site owners, lessees,
or operators.
See applicable operational BMPs in Fact
Sheet SC-44, “Drainage System
Maintenance,” in the CASQA Stormwater
Quality Handbooks at
www.cabmphandbooks.com
- 23 -
Include the following in lease agreements:
“Tenant shall not allow anyone to
discharge anything to storm drains or to
store or deposit materials so as to create a
potential discharge to storm drains.”
Landscape/Outdoor
Pesticide use*
Final landscape plans will
accomplish all of the
following.
Preserve existing native
trees, shrubs, and ground
cover to the maximum
extent possible.
Design landscaping to
minimize irrigation and
runoff, to promote surface
infiltration where
appropriate, and to
minimize the use of
fertilizers and pesticides
that can contribute to
stormwater pollution.
Where landscaped areas
are used to retain or detain
stormwater, specify plants
that are tolerant of
saturated soil conditions.
Consider using pest-
resistant plants, especially
adjacent to hardscape.
To insure successful
establishment, select plants
appropriate to site soils,
slopes, climate, sun, wind,
rain, land use, air
movement, ecological
consistency, and plant
interactions.
Maintain landscaping using minimum or
no pesticides.
See applicable operational BMPs in “What
you should know for….Landscape and
Gardening” at
https://www.rcwatershed.org/wpcontent/
uploads/2015/12/Landscapingand-
Gardening-Guide.pdf
Provide IPM information to new owners,
lessees, and operators.
Food Service* N/A N/A
Refuse Areas*
Several site refuse trash
enclosures are included in
the proposed plan. Refuse
will be removed from the
site by the City refuse
department/contractors.
Provide adequate number of receptacles.
Inspect receptacles regularly; repair or
replace leaky receptacles. Keep
receptacles covered. Prohibit/prevent
dumping of liquid or hazardous wastes.
Post “no hazardous materials” signs.
Inspect and pick up litter daily and clean
up spills immediately. Keep spill control
- 24 -
Signs will be posted on or
near dumpsters with the
words “Do not dump
hazardous materials here”
or similar.
materials available on-site. See Fact Sheet
SC-34, “Waste Handling and Disposal” in
the CASQA Stormwater Quality
Handbooks at
www.cabmphandbooks.com
Loading docks*
N/A
Move loaded and unloaded items indoors
as soon as possible.
See Fact Sheet SC-30, “Outdoor Loading
and Unloading,” in the CASQA Stormwater
Quality Handbooks at
www.cabmphandbooks.com
Fire Sprinkler Test Water*
Provide a means to drain
fire sprinkler test water to
the sanitary sewer.
See the note in Fact Sheet SC-41, “Building
and Grounds Maintenance,” in the CASQA
Stormwater Quality Handbooks at
www.cabmphandbooks.com
Miscellaneous Drain or
Wash Water or Other
Sources:
Condensate drain lines
Rooftop equipment
Roofing, gutters, and trim.
Condensate drain lines may
discharge to landscaped
areas if the flow is small
enough that runoff will not
occur. Condensate drain
lines may not discharge to
the storm drain system.
Rooftop equipment with
potential to produce
pollutants shall be roofed
and/or have secondary
containment.
Avoid roofing, gutters, and
trim made of copper or
other
unprotected metals that
may leach into runoff.
N/A
Plazas, sidewalks, and
parking *lots* N/A
Sweep plazas, sidewalks, and parking lots
regularly to prevent accumulation of litter
and debris. Collect debris from pressure
washing to prevent entry into the storm
drain system. Collect washwater
containing any cleaning agent or
degreaser and discharge to the sanitary
sewer not to a storm drain.
*See Appendix 8
- 25 -
Section H: Construction Plan Checklist (To be Filled out in Final WQMP)
Populate Table H.1 below to assist the plan checker in an expeditious review of your project. The first two
columns will contain information that was prepared in previous steps, while the last column will be
populated with the corresponding plan sheets. This table is to be completed with the submittal of your
final Project-Specific WQMP.
Table H.1 Construction Plan Cross-reference
BMP No. or ID BMP Identifier and Description Corresponding Plan Sheet(s)
Units A-K Filterra Bioretention/BioFiltration Systems TBD Storm Drain Plans
Note that the updated table — or Construction Plan WQMP Checklist — is only a reference tool to facilitate
an easy comparison of the construction plans to your Project-Specific WQMP. Co-Permittee staff can
advise you regarding the process required to propose changes to the approved Project-Specific WQMP.
- 26 -
Section I: Operation, Maintenance and Funding
The Copermittee will periodically verify that Stormwater BMPs on your site are maintained and continue
to operate as designed. To make this possible, your Copermittee will require that you include in Appendix
9 of this Project-Specific WQMP:
1. A means to finance and implement facility maintenance in perpetuity, including replacement
cost.
2. Acceptance of responsibility for maintenance from the time the BMPs are constructed until
responsibility for operation and maintenance is legally transferred. A warranty covering a period
following construction may also be required.
3. An outline of general maintenance requirements for the Stormwater BMPs you have selected.
4. Figures delineating and designating pervious and impervious areas, location, and type of
Stormwater BMP, and tables of pervious and impervious areas served by each facility. Geo-
locating the BMPs using a coordinate system of latitude and longitude is recommended to help
facilitate a future statewide database system.
5. A separate list and location of self-retaining areas or areas addressed by LID Principles that do
not require specialized O&M or inspections but will require typical landscape maintenance as
noted in Chapter 5, pages 85-86, in the WQMP Guidance. Include a brief description of typical
landscape maintenance for these areas.
Your local Co-Permittee will also require that you prepare and submit a detailed Stormwater BMP
Operation and Maintenance Plan that sets forth a maintenance schedule for each of the Stormwater BMPs
built on your site. An agreement assigning responsibility for maintenance and providing for inspections
and certification may also be required.
Details of these requirements and instructions for preparing a Stormwater BMP Operation and
Maintenance Plan are in Chapter 5 of the WQMP Guidance Document.
Maintenance Mechanism: Home Owner’s Association (HOA)
Will the proposed BMPs be maintained by a Home Owners’ Association (HOA) or Property Owners
Association (POA)?
Y N
Include your Operation and Maintenance Plan and Maintenance Mechanism in Appendix 9. Additionally,
include all pertinent forms of educational materials for those personnel that will be maintaining the
proposed BMPs within this Project-Specific WQMP in Appendix 10.
- 27 -
Appendix 1: Maps and Site Plans
Location Map, WQMP Site Plan and Receiving Waters Map
CORPORATIONWILSON MIKAMI····
- 28 -
Appendix 2: Construction Plans
Grading and Drainage Plans
Site Plan
LOT 1BBCCDDDDEEEEDDDDEEEEEEEEEEEEEEFFFFHHGGAAGGEEWILSON MIKAMICORPORATIONPREPARED BY:OWNER:SHEETOF1DESCRIPTIONDATEREVISIONAPPROVEDTENTATIVE TRACT NO. 3837818 ACRE PROPERTY - LAKESHORE DRIVESUBDIVIDER:CIVILExp.FOR CONDOMINIUM PURPOSESPROJECT LOCATIONVICINITY MAPSECTION "D-D"(TYPICAL STREET)SECTION "C-C"(ENTRY STREET)SECTION "B-B"(ENTRY STREET)SECTION "E-E"(TYP. MOTOR COURT)WATER & SEWERELSINORE VALLEY MUNICIPALWATER DISTRICT (EVMWD)31315 CHANEY STREETLAKE ELSINORE, CA 92530ELECTRICSOUTHERN CALIFORNIA EDISON32815 FREESIA WAYTEMECULA, CA 92592GASSOUTHERN CALIFORNIA GASCOMPANY25620 JEFFERSON AVE.MURRIETA, CA 92562TELEPHONE / CABLE TELEVISIONVERIZON / GTE - (800) 483-1000AT&T - (800) 310-2355TIME WARNER - (888) 354-9622STORMWATERCITY OF LAKE ELSINORE130 SOUTH MAIN ST.LAKE ELSINORE, CA 92530WASTE MANAGEMENTCR&R1706 GOETZ RD.PERRIS, CA 92570ASSESSOR PARCEL NUMBERS370-050-019370-050-020370-050-032PROPOSED PHASINGSINGLE PHASE CONSTRUCTIONA. OFFSITE IMPROVMENTSWITHIN LAKESHORE DRIVEB. ROUGH GRADINGC. ONSITE & OFFSITE UTILITIESD. PRECISE GRADINGF. BUILDING CONSTRUCTIONF. SITEWORK & LANDSCAPING’ ” ’ ” C.1ENGINEER'S NOTESPUBLIC PARK DEDICATIONDATE OF FILING: 10/18/22THE DEVELOPMENT AT MISSION TRAILS -LAKE ELSINORE, LLCLAKE ELSINORE MISSION TRAIL. LLCVICTORIAN LANE(TYPICAL STREET)FUTURE IMPROVEMENTSASUBDIVISION LOT SUMMARYLOT 1: CONDOMINIUM DEVELOPMENT LOT EXISTING RIGHT OF WAY RIGHT OF WAY DEDICATION NET SITE AREA****NET SITE AREA INCLUDES COMMON OPENSPACE, PRIVATE STREETS, AND EASEMENTSPER BELOW:COMMON OPEN SPACEPRIVATE STREETSEASEMENTSAREA (SF)749,850-12,140737,61053,924228,647228,647AREA (AC)17.21-0.2816.931.245.255.25
WILSON MIKAMICORPORATIONPREPARED BY:OWNER:SHEETOF1DESCRIPTIONDATEREVISIONAPPROVEDTENTATIVE TRACT NO. 3837818 ACRE PROPERTY - LAKESHORE DRIVESUBDIVIDER:CIVILExp.FOR CONDOMINIUM PURPOSESC.1 (2)LAKE ELSINORE MISSION TRAIL. LLCLAKE ELSINORE MISSION TRAIL. LLC
COMMON OPEN SPACELOT A LOT ALOT D
LOT 1STREET "A"STREET "A"STREET "A"STREET "A"STREET "A"CORPORATIONWILSON MIKAMI03/04/2022 1st SUBMITTALJurisdiction #LAKE ELSINORE, CAWMC PROJECT NO. 10397.00LAKE ELSINORE MISSION TRAIL, LLC1020 Second St., Suite CEncinitas, CA 92024949.632.312218 ACRE PROPERTY - MISSION TRAILGRADING & DRAINAGEC.2EARTHWORK SUMMARYRAW CUT:24,000 CYRAW FILL: 21,690 CYSHRINKAGE (10%):(2,410) CYNET: 0 CYNOTE:EARTHWORK QUANTITIES DO NOT INCLUDEDREMEDIAL GRADING QUANTITIES ANDADJUSTMENTS FOR SUBSIDENCE.
F.E.LOT 1
CORPORATION
WILSON MIKAMI
03/04/2022 1st SUBMITTALJurisdiction #
LAKE ELSINORE, CA
WMC PROJECT NO. 10397.00
LAKE ELSINORE MISSION TRAIL, LLC
1020 Second St., Suite C
Encinitas, CA 92024
949.632.3122
18 ACRE PROPERTY - MISSION TRAIL SITE PLAN C.3CIVIL
Exp.
680'
SITE SUMMARYRESIDENTIAL PARKING SUMMARYGENERAL PLAN DESIGNATION:EXISTING ZONING DESIGNATION:
EXISTING LAND USE:
FOR CONDOMINIUM PURPOSES
EAST LAKE SPECIFIC PLAN MIXED USE OVERLAY
CORPORATIONWILSON MIKAMILAKE ELSINORE, CAWMC PROJECT NO. 10397.00LAKE ELSINORE MISSION TRAIL, LLC1020 Second St., Suite CEncinitas, CA 92024949.632.312218 ACRE PROPERTY - MISSION TRAILCONCEPT UTILITY PLANC.476
F.E.CORPORATIONWILSON MIKAMILAKE ELSINORE, CAWMC PROJECT NO. 10408.00LAKE ELSINORE MISSION TRAIL, LLC1020 Second St., Suite CEncinitas, CA 92024949.632.312218 ACRE PROPERTY - MISSION TRAILMAINTENANCE PLANC.5LEGENDMAINTENANCERESPONSIBILITY76
- 29 -
Appendix 3: Soils Information
Geotechnical Study and Other Infiltration Testing Data
- 30 -
Appendix 4: Historical Site Conditions (N/A)
Phase I Environmental Site Assessment or Other Information on Past Site Use
Not Applicable
- 31 -
Appendix 5: LID Infeasibility
LID Technical Infeasibility Analysis
- 32 -
LID Infeasibility Analysis:
The Project (18-acre Site on Mission Trail - Tentative Tract 38378) is proposing an Alternative
Compliance Treatment Control BMP for the project due to the infeasibility of Bioretention at the site
based on the following information/constraints.
• A Bioretention basin at the site will require an underdrain due to infiltration being not applicable
per Section D.1 of the WQMP. In addition, Silty/Clayey soil found on-site provides low
infiltration rates that makes infiltration on-site infeasible.
• A Bioretention basin underdrain must discharge to a downstream storm drain. The depth of
the underdrain is approximately 4-4.5 ft deep below the finish surface of the Bioretention basin.
The existing downstream storm drain for the site is located approximately 1,525 ft from the
Bioretention basin underdrain location. The depth of the storm drain at that location is 3.2 ft
which is 1.3 ft higher than the underdrain. The Site grading would need to be raised 1.3 ft in
order to connect the underdrain to the storm drain. The site grading is balance (24,000 cut and
fill). Raising the site 1.3 feet would result in excess of 30,000 cy of imported soil which is not
feasible.
• Proposed retaining walls on the northwest side of the site would need to be increased to 8 ft
high with an additional 8 ft high sound wall on top. This configuration is not considered feasible.
A Bioretention basin will require an area of approximately 19,000 square feet within the private
park area within the site. The basin would use approximately 50% of the park area which will
eliminate amenities and make that area unusable for residents. The use of a alternative
compliance BMP results in a much more livable community.
- 33 -
Appendix 6: BMP Design Details
BMP Sizing, Design Details and other Supporting Documentation
- 34 -
Filterra Bioretention/Biofiltration System Units BMP Sizing Calculations
Table of Contents
1. Alternative Compliance Documents for Filterra Bioretention/Biofiltration System:
a. Los Angeles Los Angeles Regional Water Quality Control Board Approval of
Alternative Biofiltration Specification (4 Pages)
b. Filterra Equivalency Analysis and Design Criteria pursuit to Los Angeles County
MS4 Permit, Geosyntec Consultants (50 Pages)
i. Documents the Treatment Equivalency Analysis between the Filterra
Bioretention/Biofiltration and Conventional Bioretention/Biofiltration (LID
BMP)
ii. Efficiency Pollutant Removal Rates for Pesticides, Sediment, Trash and
Debris and Oil and Grease as Pollutants of Concern: See Section 3.3
Pages 5 through 11
iii. BMP Design Methodology: See Section 4, Pages 12-15
2. Filterra Bioretention Systems: Technical Basis for High Flow Rate Treatment and
Evaluation of Stormwater Quality Performance, Herrera Environmental Consultants (39
Pages): Additional Reference Study for Filterra Stormwater Quality Performance
3. BMP Design Calculations (12 Pages)
4. BMP Sizing Specification and Typical Plans/Details (12 Pages)
Los Angeles Regional Water Quality Control Board
December 30, 2019
Paul Alva
Assistant Deputy Director
County of Los Angeles
900 South Fremont Avenue
Alhambra, CA 91803
VIA EMAIL
APPROVAL OF ALTERNATIVE BIOFILTRATION SPECIFICATION PURSUANT TO
PART VI.D.7.c.iii.(1)(b)(i) OF THE LOS ANGELES COUNTY MUNICIPAL SEPARATE
STORM SEWER SYSTEM (MS4) PERMIT (NPDES PERMIT NO. CAS004001;
ORDER NO. R4-2012-0175 AS AMENDED BY STATE WATER BOARD ORDER WQ
2015-0075 AND LOS ANGELES WATER BOARD ORDER R4-2012-0175-A01)
Dear Mr. Alva:
On June 20, 2019, and August 8, 2019 for the City of Lomita, the Los Angeles Regional
Water Quality Control Board (Los Angeles Water Board) received a letter from the
County of Los Angeles (County), on behalf of the Contract Cities,1 requesting approval
for the use of Filterra Bioretention Systems (Filterra) manufactured by Contech
Engineered Solutions LLC as an alternative biofiltration design specification.
The County’s request includes an excerpt from a document entitled “Filterra
Equivalency Analysis and Design Criteria” (Equivalency Analysis) as an attachment,
that details a proposed design approach and equivalency criteria for Filterra to achieve
equivalent performance to the biofiltration design specifications defined in the Los
Angeles County MS4 Permit.
Pursuant to Part VI.D.7.c.iii.(1)(b)(i) of the Los Angeles County MS4 Permit, projects
using biofiltration as an alternative compliance measure may use alternative design
1 The County of Los Angeles provides land development review services for the cities of
Carson, Irwindale, La Cañada Flintridge, Lomita, Rolling Hills Estates and Westlake
Village (Contract Cities).
Mr. Paul Alva - 2 - December 30, 2019
County of Los Angeles
specifications for on-site biofiltration systems if approved by the Los Angeles Water
Board Executive Officer.
Background
Part VI.D.7 of the Los Angeles County MS4 Permit requires Permittees to implement a
Planning and Land Development Program. As part of this program, Permittees shall
require all New Development and Redevelopment projects identified in Part VI.D.7.b
(hereinafter “new projects”) to control pollutants, pollutant loads, and runoff volume
emanating from the project site. Except as provided in Part VI.D.7.c.ii (Technical
Infeasibility or Opportunity for Regional Ground Water Replenishment), Part VI.D.7.d.i
(Local Ordinance Equivalence), or Part VI.D.7.c.v (Hydromodification), each Permittee
shall require new projects to retain on-site the Stormwater Quality Design Volume
(SWQDv).
Pursuant to Part VI.D.7.c.iii.(1) of the Los Angeles County MS4 Permit, Permittees may
allow new projects to use on-site biofiltration when the project applicant has
demonstrated that it is technically infeasible to retain 100 percent of the Stormwater
Quality Design Volume (SWQDv) on-site. If a Permittee conditions a project using
biofiltration due to demonstrated technical infeasibility, then the new project must
biofiltrate 1.5 times the portion of the SWQDv that is not reliably retained on-site, as
calculated by the following equation:
Where: Bv = biofiltration volume
SWQDv = the stormwater runoff from a 0.75 inch, 24-hour storm or
the 85th percentile storm, whichever is greater
Rv = volume reliably retained on-site
As a condition for on-site biofiltration, bioretention/biofiltration systems shall meet the
design specifications provided in Attachment H of the Los Angeles County MS4 Permit
unless otherwise approved by the Los Angeles Board Executive Officer.
Public Review
On September 30, 2019, the Los Angeles Water Board provided public notice and a 30-
day period to allow for public review and written comment on the proposed use of
Filterra alternative biofiltration design specification. No comments were received.
Alternative Biofiltration Specification Approval
I hereby approve the County’s proposal for the use of Filterra as an alternative on-site
biofiltration design specification pursuant to Part VI.D.7.c.iii(1)(b)(i) of the Los Angeles
County MS4 Permit, provided the following conditions are met:
Mr. Paul Alva - 3 - December 30, 2019
County of Los Angeles
1. Sizing: The County shall verify the appropriateness of the recommended loading
rates used in the “Filterra Equivalency Analysis and Design Criteria”.
If the County finds no issues with the loading rate, Filterra systems must be
designed and sized following the methodology in Section 4 of the August 2015
report entitled “Filterra Equivalency Analysis and Design Criteria”.
If the County finds that the recommended loading rate is too high, Filterra
systems must be designed and sized to account for an appropriate lower loading
rate.
2. O&M: Operation and maintenance of Filterra systems must be conducted
consistent with the recommendations in the Filterra maintenance manual
provided by the manufacturer and any revisions thereto.
3. Media: Filterra systems use an engineered biofiltration media. Filterra systems,
including the engineered biofiltration media, must be provided by the
manufacturer. No substitution of materials/media is allowed.
4. Hydromodification: There is no presumption by this approval that a Permittee’s
implementation of the abovementioned design parameters and use specifications
of the Filterra system meet the separate hydromodification requirements of
Section VI.D.7.c.iv of the Los Angeles County MS4 Permit. Hydromodification
requirements apply regardless of the type of biofiltration system used.
This approval only applies to the use of Filterra as an alternative on-site biofiltration
design in situations where a project applicant has demonstrated that it is technically
infeasible to retain 100 percent of the SWQDv on-site. Furthermore, this approval does
not constitute certification or verification of the performance of the Filterra since the Los
Angeles Water Board does not have a testing and certification program for treatment
control BMPs. This approval is given based on the supporting documentation provided
in the request and relies on the County’s review of the system.
The County shall comply with Maintenance Agreement and Transfer requirements
outlined in Part VI.D.7.d.iii of the Los Angeles County MS4 Permit. These requirements
include:
1. Part VI.D.7.d.iii – prior to issuing approval for final occupancy, the County shall
require new development and redevelopment projects subject to post-
construction BMP requirements to provide an operation and maintenance plan;
monitoring plan, where required; and verification of ongoing maintenance
provisions for LID practices, treatment control BMPs, and hydromodification
control BMPs.
2. Part VI.D.7.d.iii.(1)(a) – verification of post-construction BMP maintenance
agreement shall include all the documents included in this provision.
Mr. Paul Alva - 4 - December 30, 2019
County of Los Angeles
3. Part VI.D.7.d.iii.(1)(b) – the County shall ensure a plan is developed for the
operation and maintenance of all structural and treatment controls. The County
shall examine the plan for relevance to keeping the BMPs in proper working
order. Furthermore, operation and maintenance plans for private BMPs shall be
kept on-site for periodic review by County inspectors.
4. Part VI.D.7.d.iv.(c) – the County shall verify proper maintenance and operation of
post-construction BMPs operated by the County.
5. Part VI.D.7.d.iv.(d) – for post-construction BMPs operated and maintained by
parties other than the County, the County shall require the other parties to
document proper maintenance and operations.
6. Part VI.D.7.d.iv.(e) – the County shall undertake any enforcement as appropriate
per the established progressive enforcement policy.
If you have any questions, please contact Ms. Susana Vargas of the Storm Water
Permitting Unit at Susana.Vargas@waterboards.ca.gov or by phone at (213) 576-6688.
Alternatively, you may also contact Ivar Ridgeway, Chief of the Storm Water Permitting
Unit, at Ivar.Ridgeway@waterboards.ca.gov or by phone at (213) 620-2150.
Sincerely,
Renee Purdy
Executive Officer
FILTERRA EQUIVALENCY ANALYSIS
AND DESIGN CRITERIA
Pursuant to:
Los Angeles County MS4 Permit
(Order R4-2012-0175)
Prepared for
CONTECH Engineered Solutions
Prepared by
621 SW Morrison Street, Suite 600
Portland, Oregon 97205
August 2015
Filterra Equivalency Analysis
August 2015
i
TABLE OF CONTENTS
Table of Contents ............................................................................................................... i
1 Introduction ........................................................................................................... 1
2 BMP descriptions .................................................................................................. 2
2.1 Conventional Biofiltration ........................................................................... 2
2.2 Filterra Systems ........................................................................................... 2
3 Basis and Methdology for Evaluating Equivalency .............................................. 4
3.1 Basis for Equivalency .................................................................................. 4
3.2 Methods and Assumptions for Establishing Baseline Biofiltration
Performance ................................................................................................. 4
3.2.1 Hydrologic Performance (Capture Efficiency and Volume Reduction)
........................................................................................................ 4
3.2.2 Pollutant Treatment ........................................................................ 5
3.3 Filterra Analysis to Determine Equivalent Design Criteria ......................... 6
3.3.1 Capture Efficiency .......................................................................... 6
3.3.2 Volume Reduction (Filterra and Supplemental Infiltration Storage)7
3.3.3 Pollutant Treatment ........................................................................ 8
3.3.4 Additional Capture In Lieu of Volume Reduction ......................... 9
4 Design Methodology and Equivalency Criteria .................................................. 12
5 Discussion and Conclusions ............................................................................... 16
5.1 Key Observations and Findings ................................................................. 16
5.2 Reliability and Limitations ........................................................................ 17
6 References ........................................................................................................... 19
Appendix A – Conventional Biofiltration Design Assumptions for Performance Modeling
21
Appendix B – SWMM Modeling Methodology and Assumptions ................................ 23
Equivalency Scenarios ........................................................................................ 23
Overview of SWMM Analysis Framework ........................................................ 23
Meteorological Inputs ......................................................................................... 25
Precipitation ............................................................................................... 25
ET Parameters ............................................................................................ 26
Runoff Parameters .............................................................................................. 27
BMP Representation ........................................................................................... 28
Conventional Biofiltration ......................................................................... 29
Filterra 30
Appendix C – Datasets and Analysis Methods for Pollutant Treatment Evaluation ...... 32
Data Development and Analysis Framework ..................................................... 32
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ii
Compilation and Screening of Conventional Biofiltration Studies .................... 32
Screening Process for Developing Conventional Biofiltration Sample Pool32
Screening Results ....................................................................................... 35
Inventory of Bioretention Studies and Screening Results/Rationales ....... 35
Compilation of Filterra Studies ........................................................................... 36
Data Analysis Method......................................................................................... 37
Land Use Stormwater Quality Inputs and Assumptions ..................................... 38
Appendix D – Results of Pollutant Treatment Data Analysis ........................................ 42
Filterra Equivalency Analysis
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1 INTRODUCTION
The Los Angeles County MS4 Permit (Order No. R4-2012-0175) (MS4 Permit) defines
“biofiltration” based on specific design and sizing criteria1. In addition, the MS4 Permit allows
the Los Angeles County Regional Water Quality Control Board (Regional Board) Executive
Officer to approve alternate biofiltration design criteria. The purpose of this analysis was to
develop a design basis for Filterra systems such that these systems will provide reasonably
equivalent performance to biofiltration BMPs as defined in the MS4 Permit. This report is
provided to the Executive Officer of the Regional Board to support approval of alternative design
criteria for Filterra systems. This report describes the basis for evaluating equivalency, details the
design approach and equivalency criteria for Filterra systems to achieve equivalent performance
to conventional biofiltration, and provides the supporting rationales for these equivalency
criteria.
The remainder of this report is organized as follows:
Section 2 – BMP Descriptions
Section 3 – Basis and Methodology for Evaluating Equivalency
Section 4 – Filterra Design Approach and Equivalency Criteria
Section 5 – Discussion and Conclusions
Section 6 – References
Appendix A – Design Assumptions for Conventional Biofiltration
Appendix B – SWMM Modeling Methodology and Assumptions
Appendix C – Datasets and Analysis Methods for Pollutant Treatment Evaluation
Appendix D – Results of BMP Treatment Performance Evaluation
1 BMPs sized and designed per these criteria are referred to in this memorandum as “traditional biofiltration.”
Filterra Equivalency Analysis
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2 BMP DESCRIPTIONS
2.1 Conventional Biofiltration
Biofiltration (also known as bioretention with underdrain) consists of shallow landscaped
depressions that capture and filter stormwater runoff through a planted engineered media. These
facilities function as soil and plant-based filtration systems that remove pollutants through a
variety of physical, biological, and chemical treatment processes. Biofiltration facilities normally
consist of a ponding area, mulch layer, planting soils, and plantings (see typical schematic in
Figure 1). An optional gravel layer added below the planting soil coupled with an upturned
elbow (or similar hydraulic control approach) can provide additional storage volume for
infiltration. As stormwater passes down through the planting soil, pollutants are filtered,
adsorbed, and biodegraded by the soil and plants. As defined in Attachment H of the 2012 Los
Angeles County MS4 Permit, biofiltration designs must meet a number of specific criteria to be
considered “biofiltration” as part of compliance with the MS4 Permit. Conventional biofiltration
is typically designed as a “volume-based” BMP, meaning that is it sized based on capture of the
runoff from a specific size of storm event.
Figure 1. Cross sections of typical biofiltration system
2.2 Filterra Systems
Filterra systems include engineered filter media topped with mulch housed in a precast concrete
curb inlet structure with a tree frame and grate cast in the top slab. In addition to the water
quality filtering/sorption of stormwater, the engineered media and mulch supports the growth of
a tree or other type of plant (see typical configuration in Figure 2). There are three key
components of the Filterra system that contribute to pollutant removal: mulch, engineered filter
media, and vegetation and other system biota. Filterra systems can be configured so that
underdrains discharge into downstream retention storage systems. In contrast to conventional
Filterra Equivalency Analysis
August 2015
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biofiltration, the media filtration rates of Filterra systems are substantially higher, and therefore
the footprint of these systems tends to be substantially smaller than conventional biofiltration
systems. As a result of smaller footprints, the amount of volume reduction (via infiltration and
evapotranspiration) that is typically observed in these systems when not coupled with infiltration
systems tends to be relatively low. Because these systems provide relatively limited ponded
water volume above the surface of the media, they are typically sized as “flow-based” BMPs
based on a design intensity of rainfall rather than “volume-based” BMP based on a design storm
depth.
Figure 2. Diagram of the Filterra system (Contech, 2015 via web).
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3 BASIS AND METHDOLOGY FOR EVALUATING EQUIVALENCY
3.1 Basis for Equivalency
Equivalency was evaluated between conventional biofiltration BMPs meeting the criteria of the
MS4 Permit (specifically Attachment H) and Filterra systems as an alternate biofiltration BMP.
Equivalency was determined based on the factors that influence the pollutant load reduction
performance of stormwater BMPs:
Capture efficiency: The percent of long term stormwater runoff volume that is
“captured” and managed by the BMP (i.e., treated or reduced; not overflowed or
bypassed).
Volume reduction: The percent of long term stormwater runoff volume that is “lost” or
“reduced” in the BMP to infiltration and evapotranspiration.
Concentration reduction: For the volume that is treated and not reduced, the average
difference in concentration between the influent volume and the treated effluent volume.
The equivalency analysis consisted of three parts:
1) The baseline performance of conventional biofiltration (capture efficiency, volume
reduction, and concentration reduction) was estimated.
2) Applying the same methods as used to evaluate the performance of conventional
biofiltration, sizing criteria were developed for Filterra (accompanied by supplemental
infiltration systems, where needed) such that Filterra systems will provide equivalent
performance to conventional biofiltration.
3) A design methodology for Filterra systems was developed to ensure consistent
application of the equivalent sizing criteria in the design of Filterra systems.
The following subsections provide information about this analysis.
3.2 Methods and Assumptions for Establishing Baseline Biofiltration Performance
The following subsections summarize the methods and assumptions that were used to evaluate
the baseline performance of conventional biofiltration BMPs consistent with Attachment H of
the MS4 Permit.
3.2.1 Hydrologic Performance (Capture Efficiency and Volume Reduction)
Attachment H of the MS4 Permit specifies a number of criteria that influence the hydrologic
performance of the conventional biofiltration BMPs:
6 to 18-inch ponding area above media
Optional layer of mulch
2 to 3 feet of engineered filter media (2 feet typical) with a design infiltration rate of 5 to
12 inches/hour; the Attachment H specification calls for a mix of 60 to 80% fine sand and
20 to 40% compost
Filterra Equivalency Analysis
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Gravel storage layer below the bioretention media to promote infiltration
Underdrain placed near the top of the gravel layer (or an infiltration sump otherwise
provided via an equivalent hydraulic control approach) in cases where underlying soil
allows incidental infiltration
Underdrain discharge to the storm drain
Capacity (including stored and filtered water) adequate to biofilter 150 percent of the
portion of the SWQDv not reliably retained.
Within the bounds established by these criteria, a relatively wide range of actual biofiltration
designs could result as a function of site infiltration conditions as well as designer and local
jurisdiction preferences. An example of potential design variability is illustrated in Appendix A.
For the purpose of this analysis, representative design assumptions were developed within the
range of potential design assumptions. These assumptions are also presented in Appendix A with
supporting rationales. Long term continuous simulation SWMM modeling was conducted using
15 years of 5-minute resolution precipitation data, as described in Appendix B, to estimate the
long term capture efficiency and volume reduction of the baseline biofiltration design scenario
for a range of site infiltration rates. Biofiltration BMPs will tend to provide more volume
reduction when installed in sites with higher incidental infiltration rates. Table 1 describes the
baseline hydrologic performance of biofiltration BMPs.
Table 1. Baseline Biofiltration Hydrologic Performance
Site Soil Infiltration Rate,
in/hr
Long Term Capture Efficiency
(percent of total runoff
volume)
Long Term Volume Reduction
(percent of total runoff
volume) (ET + Infiltration)
0
92 to 94%1
(93% capture is
representative)
4%
0.01 6%
0.05 11%
0.15 22%
0.302 35%
1 - Capture efficiency varies slightly as a function of soil infiltration rate (and associated differences in design
profile) and land use imperviousness. These differences are relatively minor and are considered to be less important
than the variability in performance that may result from different design approaches and maintenance conditions that
may be encountered. Therefore a single baseline value of 93 percent long term capture was used in this analysis.
2 - A maximum soil infiltration rate of 0.3 inches per hour was evaluated because for soil infiltration rates greater
than 0.3 inches per hour the MS4 Permit requires that infiltration be evaluated.
3.2.2 Pollutant Treatment
Pollutant treatment performance was evaluated based on analysis of bioretention with underdrain
studies in the International Stormwater BMP Databases. Analyses were conducted based on all
studies (28 studies) and a screened subset of studies that were considered to be most
representative of Attachment H design criteria (16 studies). Additionally, two recent studies from
the University of Maryland were added which followed rigorous protocols and evaluated systems
sharing many similarities to Attachment H design criteria. Biofiltration research in California is
very limited. Two recent monitoring studies were conducted in the San Francisco Bay area (led