HomeMy WebLinkAboutAppendix K - WQMP
Thienes Engineering, Inc.
CIVIL ENGINEERING LAND SURVEYING
Storm Water Quality Management Plan
(SWQMP)
For:
Santa Ana Avenue Industrial Building
SWC of Santa Ana Avenue and Banana Avenue
Fontana, CA 92337
APNs: 0236‐161‐04, ‐10, ‐31, ‐32, ‐33, ‐35, ‐36, ‐44, ‐45, ‐46 and ‐77
Prepared for:
QR Birtcher Banana Ave. Owner LLC
450 Newport Center Drive, Suite 220
Newport Beach, CA 92600
Phone: (949) 355‐5278
Contact: Scott Mulkay
Prepared by:
Thienes Engineering, Inc.
14349 Firestone Boulevard
La Mirada, CA 90638
Phone: (714) 521‐4811
Contact: Mira Bogdanova (mira@thieneseng.com)
Job No. 3899
Preliminary Approval Date:
Construction Approval Date:
Final Approval Date:
Preliminary Submittal: August 31, 2021
Construction Submittal:
Final Submittal:
WQMPXX‐XXXXXX
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC
Project Owner’s Certification
This Water Quality Management Plan (WQMP) has been prepared for QR Birtcher Banana Ave. Owner
LLC by Thienes Engineering, Inc. The WQMP is intended to comply with the requirements of the City of
Fontana and the NPDES Areawide Stormwater Program requiring the preparation of a WQMP.
The undersigned, while it owns the subject property, is responsible for the implementation of the
provisions of this plan and will ensure that this plan is amended as appropriate to reflect up‐to‐date
conditions on the site consistent with the San Bernardino County’s Municipal Storm Water Management
Program and the intent of the NPDES Permit for San Bernardino County and the incorporated cities of
San Bernardino County within the Santa Ana Region. Once the undersigned transfers its interest in the
property, its successors in interest and the city/county shall be notified of the transfer. The new owner
will be informed of its responsibility under this WQMP. A copy of the approved WQMP shall be available
on the subject site in perpetuity.
“I certify under a penalty of law that the provisions (implementation, operation, maintenance, and fund)
of the WQMP have been accepted and that the plan will be transferred to future successors.”
Project Data
Permit/Application
Number(s): WQMPXX‐XXXXXX Grading Permit Number(s): TBD
Tract/Parcel Map
Number(s): Building Permit Number(s): TBD
CUP, SUP, and/or APN (Specify Lot Numbers if Portions of Tract): APN: 0236‐161‐04, ‐10, ‐31, ‐32, ‐33, ‐35,
‐36, ‐44, ‐45, ‐46 and ‐77
Owner’s Signature
Owner Name: QR Birtcher Banana Ave. Owner LLC
Name/Title Scott Mulkay / President of Construction
Company QR Birtcher Banana Ave. Owner LLC
Address 450 Newport Center Drive, Suite 220, Newport Beach, CA 92600
Email s.mulkay@birtcher.com
Telephone # (949) 355‐5278
Signature Date
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC
Preparer’s Certification
Project Data
Permit/Application
Number(s): WQMPXX‐XXXXXX Grading Permit Number(s): TBD
Tract/Parcel Map
Number(s): Building Permit Number(s): TBD
CUP, SUP, and/or APN (Specify Lot Numbers if Portions of Tract): APN: 0236‐161‐04, ‐10, ‐31, ‐32, ‐33, ‐35,
‐36, ‐44, ‐45, ‐46 and ‐77
“The selection, sizing and design of stormwater treatment and other stormwater quality and quantity
control measures in this plan were prepared under my oversight and meet the requirements of Regional
Water Quality Control Board Order No. R8‐2010‐0036.”
Engineer: Reinhard Stenzel PE Stamp Below
Title Director of Engineering
Company Thienes Engineering, Inc.
Address 14349 Firestone Boulevard, La Mirada, CA 90638
Email reinhard@thieneseng.com
Telephone # (714) 521‐4811
Signature
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC i
Contents
Section 1 Discretionary Permit(s) .......................................................................................................... 1‐1
Section 2 Project Description ................................................................................................................. 2‐1
2.1 Project Information .................................................................................................................... 2‐1
2.2 Property Ownership/Management ........................................................................................... 2‐2
2.3 Potential Stormwater Pollutants ............................................................................................... 2‐2
2.4 Water Quality Credits ................................................................................................................ 2‐3
Section 3 Site and Watershed Description ............................................................................................ 3‐1
Section 4 Best Management Practices (BMP) ....................................................................................... 4‐1
4.1 Source Control BMP ................................................................................................................... 4‐1
4.1.1 Pollution Prevention .......................................................................................................... 4‐1
4.1.2 Preventive LID Site Design Practices .................................................................................. 4‐6
4.2 Project Performance Criteria ..................................................................................................... 4‐7
4.3 Project Conformance Analysis ................................................................................................. 4‐13
4.3.1 Site Design Hydrologic Source Control BMP .................................................................... 4‐15
4.3.2 Infiltration BMPs .............................................................................................................. 4‐17
4.3.3 Harvest and Use BMP ....................................................................................................... 4‐19
4.3.4 Biotreatment BMP ........................................................................................................... 4‐20
4.3.5 Conformance Summary ................................................................................................... 4‐24
4.3.6 Hydromodification Control BMP ...................................................................................... 4‐25
4.4 Alternative Compliance Plan (if applicable) ............................................................................. 4‐26
Section 5 Inspection and Maintenance Responsibility for Post Construction BMP .............................. 5‐1
Section 6 WQMP Attachments .............................................................................................................. 6‐1
6.1 Site Plan and Drainage Plan ....................................................................................................... 6‐1
6.2 Electronic Data Submittal .......................................................................................................... 6‐1
6.3 Post Construction ....................................................................................................................... 6‐1
6.4 Other Supporting Documentation ............................................................................................. 6‐1
6.5 WQMP Certification ................................................................................................................... 6‐2
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC ii
Forms
Form 1‐1 Project Information .................................................................................................................... 1‐1
Form 2.1‐1 Description of Proposed Project ............................................................................................. 2‐1
Form 2.2‐1 Property Ownership/Management ......................................................................................... 2‐2
Form 2.3‐1 Pollutants of Concern .............................................................................................................. 2‐2
Form 2.4‐1 Water Quality Credits .............................................................................................................. 2‐3
Form 3‐1 Site Location and Hydrologic Features ....................................................................................... 3‐1
Form 3‐2 Existing Hydrologic Characteristics for Drainage Area (DA) ....................................................... 3‐2
Form 3‐3 Watershed Description ............................................................................................................... 3‐3
Form 4.1‐1 Non‐Structural Source Control BMPs ...................................................................................... 4‐2
Form 4.1‐2 Structural Source Control BMPs .............................................................................................. 4‐4
Form 4.1‐3 Preventive LID Site Design Practices Checklist ........................................................................ 4‐6
Form 4.2‐1 LID BMP Performance Criteria for Design Capture Volume (DA 1 DMA A) ............................ 4‐7
Form 4.2‐2 Summary of HCOC Assessment ............................................................................................... 4‐9
Form 4.2‐3 HCOC Assessment for Runoff Volume ................................................................................... 4‐10
Form 4.2‐4 HCOC Assessment for Time of Concentration ....................................................................... 4‐11
Form 4.2‐5 HCOC Assessment for Peak Runoff ....................................................................................... 4‐12
Form 4.3‐1 Infiltration BMP Feasibility .................................................................................................... 4‐14
Form 4.3‐2 Site Design Hydrologic Source Control BMPs ........................................................................ 4‐16
Form 4.3‐3 Infiltration LID BMP (including underground BMPs) (DA 1 DM A) ........................................ 4‐18
Form 4.3‐4 Harvest and Use BMPs .......................................................................................................... 4‐19
Form 4.3‐5 Selection and Evaluation of Biotreatment BMP .................................................................... 4‐20
Form 4.3‐6 Volume Based Biotreatment – Bioretention and Planter Boxes with Underdrains .............. 4‐21
Form 4.3‐7 Volume Based Biotreatment – Constructed Wetlands and Extended Detention ................. 4‐22
Form 4.3‐8 Flow Based Biotreatment ...................................................................................................... 4‐23
Form 4.3‐9 Conformance Summary and Alternative Compliance Volume Estimate (DA 1 DMA A) ....... 4‐24
Form 4.3‐10 Hydromodification Control BMPs ....................................................................................... 4‐25
Form 5‐1 BMP Inspection and Maintenance ............................................................................................. 5‐1
Attachments
Attachment A: Existing Condition Site Photos
Attachment B: BMP Design Calculations & Supporting Documentation
Attachment C: WQMP Site Map
Attachment D: WQMP and Stormwater BMP Transfer, Access and Maintenance Agreement
Attachment E: Educational Materials
Attachment F: Infiltration Report
Attachment G: Hydrologic Conditions of Concern (HCOC)
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 1‐1
Section 1 Discretionary Permit(s)
Form 1‐1 Project Information
Project Name Santa Ana Avenue Industrial Building
Project Owner
Contact Name: Scott Mulkay
Mailing
Address:
450 Newport Center Drive,
Suite 220
Newport Beach, CA 92600
E‐mail
Address: s.mulkay@birtcher.com Telephone: (949) 355‐5278
Permit/Application
Number(s): WQMPXX‐XXXXXX Tract/Parcel Map Number(s):
Additional
Information/
Comments:
n/a
Description of
Project:
The project site encompasses approximately 13.40 acres. Proposed improvements to the site include a
light industrial warehouse type building and a loading dock on the southerly side of the building.
Vehicle parking will be located along the easterly side of the site. The remainder of the site will be
reserved for landscaping.
The project proposes one underground retention system for infiltration and one hydrodynamic
separator for pretreatment. The system will be located in the southerly truck yard. As shown in
Worksheet H of Attachment B, the design infiltration rate for is 9.9 in/hr which can drawdown up to
237.6 inches of stormwater within 24 hours. The effective ponding depth is 64.2 inches for the onsite
underground retention system. With this justification, the project’s design capture volume is
determined using the 1.582 regression constant for 24 hours.
Approximately 0.05 acres of driveway area along the easterly right‐of‐way will drain offsite without
being routed to the onsite BMPs for treatment. The driveway area will be accounted for in the onsite
underground retention system even though it does not physically drain there.
The project also proposes street improvements; however, they consist of less than ½ mile and
therefore not required to treat any public improvements per Appendix A of the San Bernardino
Technical Guidance Document.
Provide summary of
Conceptual WQMP
conditions (if
previously submitted
and approved).
Attach complete
copy.
n/a
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 2‐1
Section 2 Project Description
2.1 Project Information
This section of the WQMP should provide the information listed below. The information provided for
Conceptual/Preliminary WQMP should give sufficient detail to identify the major proposed site design
and LID BMPs and other anticipated water quality features that impact site planning. Final Project
WQMP must specifically identify all BMP incorporated into the final site design and provide other
detailed information as described herein.
The purpose of this information is to help determine the applicable development category, pollutants of
concern, watershed description, and long term maintenance responsibilities for the project, and any
applicable water quality credits. This information will be used in conjunction with the information in
Section 3, Site Description, to establish the performance criteria and to select the LID BMP or other BMP
for the project or other alternative programs that the project will participate in, which are described in
Section 4.
Form 2.1‐1 Description of Proposed Project
1 Development Category (Select all that apply):
Significant
re‐development involving the
addition or replacement of
5,000 ft2 or more of
impervious surface on
an already developed site
New development
involving the creation of
10,000 ft2 or more of
impervious surface
collectively over entire site
Automotive repair shops
with standard industrial
classification (SIC) codes
5013, 5014, 5541, 7532‐
7534, 7536‐7539
Restaurants (with SIC
code 5812) where the land
area of development is
5,000 ft2 or more
Hillside developments of
5,000 ft2 or more which are
located on areas with known
erosive soil conditions or
where the natural slope is
25 percent or more
Developments of 2,500
ft2 of impervious surface or
more adjacent to (within 200
ft) or discharging directly into
environmentally sensitive
areas or waterbodies listed
on the CWA Section 303(d)
list of impaired waters.
Parking lots of 5,000 ft2
or more exposed to storm
water
Retail gasoline outlets
that are either 5,000 ft2 or
more, or have a projected
average daily traffic of 100
or more vehicles per day
Non‐Priority / Non‐Category Project
May require source control LID BMPs and other LIP requirements. Please consult with local jurisdiction on specific requirements.
2 Project Area
(ft2):
583,704
(13.40 acres) *
3 Number of
Dwelling Units: n/a 4 SIC Code: 4225
5 Is Project going to be phased? Yes No
If yes, ensure that the WQMP evaluates each phase as a distinct DA, requiring LID BMPs to address runoff at time of completion.
6 Does Project include roads? Yes No
If yes, ensure that applicable requirements for road projects are addressed (see Appendix A of TGD for WQMP)
*This value includes 0.05 acres of driveway area which drains offsite. The driveway area will be
accounted for in the underground retention system even though it does not physically drain there.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 2‐2
2.2 Property Ownership/Management
Describe the ownership/management of all portions of the project and site. State whether any
infrastructure will transfer to public agencies (City, County, Caltrans, etc.) after project completion. State
if a homeowners or property owners association will be formed and be responsible for the long‐term
maintenance of project stormwater facilities. Describe any lot‐level stormwater features that will be the
responsibility of individual property owners.
Form 2.2‐1 Property Ownership/Management
Describe property ownership/management responsible for long‐term maintenance of WQMP stormwater facilities:
QR Birtcher Banana Ave. Owner LLC
450 Newport Center Drive, Suite 220
Newport Beach, CA 92600
Phone: (949) 355‐5278
Contact: Scott Mulkay
A property owner’s association (POA) will not be formed for long‐term maintenance of onsite stormwater facilities.
The owner will maintain onsite stormwater facilities as shown in Attachment D.
2.3 Potential Stormwater Pollutants
Determine and describe expected stormwater pollutants of concern based on land uses and site
activities (refer to Table 3‐3 in the TGD for WQMP).
Form 2.3‐1 Pollutants of Concern
Pollutant
Circle One:
E=Expected,
N=Not Expected
Listed for
Receiving
Water
Additional Information and Comments
Pathogens (Bacterial / Virus) E N X Bacterial indicators are routinely detected in pavement
runoff.
Nutrients ‐ Phosphorous E N Expected pollutant if landscaping exists on‐site.
Nutrients ‐ Nitrogen E N X Expected pollutant if landscaping exists on‐site.
Noxious Aquatic Plants E N Expected pollutant if landscaping exists on‐site.
Sediment E N X Expected pollutant if landscaping exists on‐site.
Metals E N
Oil and Grease E N
Trash/Debris E N
Pesticides / Herbicides E N
Organic Compounds E N Expected pollutant if landscaping exists on‐site. Including
petroleum hydrocarbons.
Other:
The expected POCs for the project site are Pathogens, Nitrogen, and Metals.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 2‐3
2.4 Water Quality Credits
A water quality credit program is applicable for certain types of development projects if it is not feasible
to meet the requirements for on‐site LID. Proponents for eligible projects, as described below, can apply
for water quality credits that would reduce project obligations for selecting and sizing other treatment
BMP or participating in other alternative compliance programs. Refer to Section 6.2 in the TGD for
WQMP to determine if water quality credits are applicable for the project.
Form 2.4‐1 Water Quality Credits
1 Project Types that Qualify for Water Quality Credits: Select all that apply
Redevelopment projects that
reduce the overall impervious
footprint of the project site.
[Credit = % impervious reduced]
Higher density
development projects
Vertical density [20%]
7 units/ acre [5%]
Mixed use development,
(combination of residential,
commercial, industrial, office,
institutional, or other land uses
which incorporate design
principles that demonstrate
environmental benefits not
realized through single use
projects) [20%]
Brownfield
redevelopment (redevelop
real property complicated
by presence or potential of
hazardous contaminants)
[25%]
Redevelopment projects in
established historic district,
historic preservation area, or
similar significant core city
center areas [10%]
Transit‐oriented
developments (mixed use
residential or commercial
area designed to maximize
access to public
transportation) [20%]
In‐fill projects (conversion
of empty lots & other underused
spaces < 5 acres, substantially
surrounded by urban land uses,
into more beneficially used
spaces, such as residential or
commercial areas) [10%]
Live‐Work
developments (variety of
developments designed to
support residential and
vocational needs) [20%]
2 Total Credit %: n/a
(Total all credit percentages up to a maximum allowable credit of 50 percent)
Description of Water Quality
Credit Eligibility (if applicable) n/a
The proposed project will not utilize any water quality credits.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 3‐1
Section 3 Site and Watershed Description
Describe the project site conditions that will facilitate the selection of BMP through an analysis of the
physical conditions and limitations of the site and its receiving waters. Identify distinct drainage areas
(DA) that collect flow from a portion of the site and describe how runoff from each DA (and sub‐
watershed DMAs) is conveyed to the site outlet(s). Refer to Section 3.2 in the TGD for WQMP. Complete
form 3.2 for each DA on the project site.
Form 3‐1 Site Location and Hydrologic Features
Site coordinates
Take GPS measurement at
approximate center of site
Latitude: 34.054284 Longitude: ‐117.49895 Thomas Bros Map page:
Page 644
1 San Bernardino County climatic region: Valley Mountain Desert
2 Does the site have more than one drainage area (DA): Yes No
If no, proceed to Form 3‐2. If yes, then use this form to show a conceptual schematic describing DMAs and hydrologic feature connecting DMAs
to the site outlet(s). An example is provided below that can be modified for proposed project or a drawing clearly showing DMA and flow routing
may be attached.
Conveyance Briefly describe on‐site drainage features to convey runoff that is not retained within a DMA
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 3‐2 Form 3‐2 Existing Hydrologic Characteristics for Drainage Area (DA) For each drainage area’s sub‐watershed DMA, provide the following characteristics Hyd Nodes 100‐101 Hyd Nodes 110‐111 Hyd Nodes 120‐121 n/a n/a 1 DMA drainage area (ft2) 324,522 (7.45 ac) 161,172 (3.70 ac) 98,010 (2.25 ac) n/a n/a 2 Existing site impervious area (ft2) 28,762 36,165 31,846 n/a n/a 3 Antecedent moisture condition For desert areas, use http://www.sbcounty.gov/dpw/floodcontrol/pdf/2 0100412_map.pdf AMC II AMC II AMC II n/a n/a 4 Hydrologic soil group Refer to Watershed Mapping Tool – http://sbcounty.permitrack.com/WAP HSG A HSG A HSG A n/a n/a 5 Longest flowpath length (ft) 752 656 616 n/a n/a 6 Longest flowpath slope (ft/ft) 0.0118 0.0098 0.0086 n/a n/a 7 Current land cover type(s) Select from Fig C‐3 of Hydrology Manual Residential/Commercial Residential/Commercial Residential/Commercial n/a n/a 8 Pre‐developed pervious area condition: Based on the extent of wet season vegetated cover good >75%; Fair 50‐75%; Poor <50% See Attachment A for photos of site to support rating Poor Poor Poor n/a n/a
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 3‐3
Form 3‐3 Watershed Description
Receiving Waters
Refer to Watershed Mapping Tool ‐
http://sbcounty.permitrack.com/WAP
See ‘Drainage Facilities” link at this website
Storm Drain southerly along Banana Ave
Declez Channel
San Sevaine Channel
Santa Ana River, Reach 3
Prado Dam
Santa Ana River, Reach 2
Santa Ana River, Reach 1
Pacific Ocean
Applicable TMDLs
Refer to Local Implementation Plan
Storm Drain southerly along Banana Ave: None
Declez Channel: None
San Sevaine Channel: None
Santa Ana River, Reach 3: Pathogens, Nitrate
Prado Dam: Pathogens
Santa Ana River, Reach 2: None
Santa Ana River, Reach 1: None
Pacific Ocean: None
303(d) listed impairments
Refer to Local Implementation Plan and Watershed
Mapping Tool –
http://sbcounty.permitrack.com/WAP
and State Water Resources Control Board website –
http://www.waterboards.ca.gov/santaana/water_iss
ues/programs/tmdl/index.shtml
Storm Drain southerly along Banana Ave: None
Declez Channel: None
San Sevaine Channel: None
Santa Ana River, Reach 3: Copper, Indicator Bacteria, Lead
Prado Dam: pH
Santa Ana River, Reach 2: None
Santa Ana River, Reach 1: None
Pacific Ocean: None
Environmentally Sensitive Areas (ESA)
Refer to Watershed Mapping Tool –
http://sbcounty.permitrack.com/WAP
N/A
Unlined Downstream Water Bodies
Refer to Watershed Mapping Tool –
http://sbcounty.permitrack.com/WAP
Santa Ana River
Hydrologic Conditions of Concern
Yes
Complete Hydrologic Conditions of Concern (HCOC) Assessment. Include Forms 4.2‐2
through Form 4.2‐5 and Hydromodification BMP Form 4.3‐10 in submittal
No (see Attachment G for applicability map)
Watershed–based BMP included in a RWQCB
approved WAP
Yes
Attach verification of regional BMP evaluation criteria in WAP
More Effective than On‐site LID
Remaining Capacity for Project DCV
Upstream of any Water of the US
Operational at Project Completion
Long‐Term Maintenance Plan
No
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐1
Section 4 Best Management Practices (BMP)
4.1 Source Control BMP
4.1.1 Pollution Prevention
Non‐structural and structural source control BMP are required to be incorporated into all new
development and significant redevelopment projects. Form 4.1‐1 and 4.1‐2 are used to describe specific
source control BMPs used in the WQMP or to explain why a certain BMP is not applicable. Table 7‐3 of
the TGD for WQMP provides a list of applicable source control BMP for projects with specific types of
potential pollutant sources or activities. The source control BMP in this table must be implemented for
projects with these specific types of potential pollutant sources or activities.
The preparers of this WQMP have reviewed the source control BMP requirements for new development
and significant redevelopment projects. The preparers have also reviewed the specific BMP required for
project as specified in Forms 4.1‐1 and 4.1‐2. All applicable non‐structural and structural source control
BMP shall be implemented in the project.
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐2 Form 4.1‐1 Non‐Structural Source Control BMPs Identifier Name Check One Describe BMP Implementation OR, if not applicable, state reason Included Not Applicable N1 Education of Property Owners, Tenants and Occupants on Stormwater BMPs X Property owner will familiarize him/herself with the educational materials in Attachment “E” and the contents of the WQMP. N2 Activity Restrictions X No outdoor work areas, processing, storage or wash area. N3 Landscape Management BMPs X Irrigation must be consistent with the local agency’s Water Conservation Ordinance. Fertilizer and pesticide usage will be consistent with local agency’s Management Guidelines for Use of Fertilizers and Pesticides. N4 BMP Maintenance X BMP maintenance, implementation schedules, and responsible parties are included with each specific BMP narrative. N5 Title 22 CCR Compliance (How development will comply) X No hazardous wastes onsite. N6 Local Water Quality Ordinances X Local agency does not have additional water quality ordinances. N7 Spill Contingency Plan X Owner/tenant will have a spill contingency plan based on individual site needs. N8 Underground Storage Tank Compliance X No USTs onsite. N9 Hazardous Materials Disclosure Compliance X No hazardous materials onsite. N10 Uniform Fire Code Implementation X Owner will comply with Article 80 of the Uniform Fire Code enforced by the fire protection agency. N11 Litter/Debris Control Program X Contract with their landscape maintenance firm to provide this service during regularly schedule maintenance. N12 Employee Training X The owner will ensure that tenants are also familiar with onsite BMPs and necessary maintenance required of the tenants. Owner will check with City and County at least once a year to obtain new or updated educational materials and provide these materials to tenants. Employees shall be trained to clean up spills and participate in ongoing maintenance. The WQMP requires annual employee training and new hires within 2 months. N13 Housekeeping of Loading Docks X Keep all fluids indoors. Clean up spills immediately and keep spills from entering storm drain system. No direct discharges into the storm drain system. Area shall be inspected weekly for proper containment and practices with spills cleaned up immediately and disposed of properly. N14 Catch Basin Inspection Program X Monthly inspection by property owner’s designee. Vacuum basins when sediment or trash becomes 2‐inches deep and dispose of properly. N15 Vacuum Sweeping of Private Streets and Parking Lots X All landscape maintenance contractors will be required to sweep up all landscape cuttings, mowings and fertilizer materials off paved areas weekly and dispose of properly. Parking areas and drive ways will be swept monthly by sweeping contractor.
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐3 Form 4.1‐1 Non‐Structural Source Control BMPs Identifier Name Check One Describe BMP Implementation OR, if not applicable, state reason Included Not Applicable N16 Other Non‐structural Measures for Public Agency Projects X Not a public agency project. N17 Comply with all other applicable NDPES permits X Will comply with Construction General Permit and Industrial General Permit (may apply for No Exposure Certification/NEC).
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐4 Form 4.1‐2 Structural Source Control BMPs Identifier Name Check One Describe BMP Implementation OR, if not applicable, state reason Included Not Applicable S1 Provide storm drain system stenciling and signage (CASQA New Development BMP Handbook SD‐13) X “No Dumping – Drains to River” stencils will be applied. Legibility of stencil will be maintained on a yearly basis. S2 Design and construct outdoor material storage areas to reduce pollution introduction (CASQA New Development BMP Handbook SD‐34) X No outdoor material storage areas onsite. S3 Design and construct trash and waste storage areas to reduce pollution introduction (CASQA New Development BMP Handbook SD‐32) X Paved with an impervious surface, designed not to allow run‐on from adjoining areas, designed to divert drainage from adjoining roofs and pavements diverted around the area, screened or walled to prevent off‐site transport of trash. Provide solid roof or awning to prevent direct contact with rainfall. S4 Use efficient irrigation systems & landscape design, water conservation, smart controllers, and source control (Statewide Model Landscape Ordinance; CASQA New Development BMP Handbook SD‐12) X Irrigation systems shall include shutoff valves triggered by a pressure drop to control water loss in the event of broken sprinkler heads or lines. Timers will be used to avoid over watering and watering cycles and duration shall be adjusted seasonally by the landscape maintenance contractor. The landscaping areas will be grouped with plants that have similar water requirements. Native or drought tolerant species shall also be used where appropriate to reduce excess irrigation runoff and promote surface filtration. S5 Finish grade of landscaped areas at a minimum of 1‐2 inches below top of curb, sidewalk, or pavement X Landscaped areas will be depressed in order to increase retention of stormwater/irrigation water and promote infiltration. S6 Protect slopes and channels and provide energy dissipation (CASQA New Development BMP Handbook SD‐10) X Not applicable; no slopes or channels to protect. S7 Covered dock areas (CASQA New Development BMP Handbook SD‐31) X Finished goods being loaded and unloaded at the docks do not have the potential to contribute to stormwater pollution. No direct connections will be made to a MS4. S8 Covered maintenance bays with spill containment plans (CASQA New Development BMP Handbook SD‐31) X No maintenance bays onsite. S9 Vehicle wash areas with spill containment plans (CASQA New Development BMP Handbook SD‐33) X No vehicle washing onsite. S10 Covered outdoor processing areas (CASQA New Development BMP Handbook SD‐36) X No outdoor processing onsite.
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐5 Form 4.1‐2 Structural Source Control BMPs Identifier Name Check One Describe BMP Implementation OR, if not applicable, state reason Included Not Applicable S11 Equipment wash areas with spill containment plans (CASQA New Development BMP Handbook SD‐33) X No equipment washing onsite. S12 Fueling areas (CASQA New Development BMP Handbook SD‐30) X No fueling onsite. S13 Hillside landscaping (CASQA New Development BMP Handbook SD‐10) X No hillsides onsite. S14 Wash water control for food preparation areas X No food preparation onsite. S15 Community car wash racks (CASQA New Development BMP Handbook SD‐33) X No community cars wash racks onsite.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐6
4.1.2 Preventive LID Site Design Practices
Site design practices associated with new LID requirements in the MS4 Permit should be considered in
the earliest phases of a project. Preventative site design practices can result in smaller DCV for LID BMP
and hydromodification control BMP by reducing runoff generation. Describe site design and drainage
plan including:
A narrative of site design practices utilized or rationale for not using practices
A narrative of how site plan incorporates preventive site design practices
Include an attached Site Plan layout which shows how preventative site design practices are
included in WQMP
Refer to Section 5.2 of the TGD for WQMP for more details.
Form 4.1‐3 Preventive LID Site Design Practices Checklist
Site Design Practices
If yes, explain how preventative site design practice is addressed in project site plan. If no, other LID BMPs must be selected to meet targets.
Minimize impervious areas: Yes No The project will utilize an infiltration facility to collect runoff from impervious
areas.
Maximize natural infiltration capacity:
Yes No The infiltration facility will maximize natural infiltration.
Preserve existing drainage patterns and
time of concentration: Yes No Post‐development drainage patterns will mimic pre‐development conditions.
Disconnect impervious areas: Yes No The infiltration facility will disconnect impervious areas before discharging
offsite.
Protect existing vegetation and sensitive
areas: Yes No
Not applicable, there are no existing vegetation onsite (see Attachment A for
recent site photos).
Re‐vegetate disturbed areas: Yes No
Not applicable, development consists of a light industrial facility. Most of the
disturbed areas will be paved; however, all disturbed areas will be collected by
the infiltration facility for treatment.
Minimize unnecessary compaction in
stormwater retention/infiltration
basin/trench areas: Yes No
Heavy construction vehicles will be prohibited from unnecessary soil
compaction at the infiltration facility location.
Utilize vegetated drainage swales in place
of underground piping or imperviously
lined swales: Yes No
Underground piping and imperviously lined swales are located in traffic areas
and could not be substituted with a vegetated swale.
Stake off areas that will be used for
landscaping to minimize compaction during
construction : Yes No
Landscaped areas will be staked to minimize unnecessary compaction during
construction.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐7
4.2 Project Performance Criteria
The purpose of this section of the Project WQMP is to establish targets for post development hydrology
based on performance criteria specified in the MS4 Permit. These targets include runoff volume for
water quality control (referred to as LID design capture volume), and runoff volume, time of
concentration, and peak runoff for protection of any downstream waterbody segments with a HCOC. If
the project has more than one outlet for stormwater runoff, then complete additional versions of
these forms for each DA / outlet.
Methods applied in the following forms include:
For LID BMP Design Capture Volume (DCV), the San Bernardino County Stormwater Program
requires use of the P6 method (MS4 Permit Section XI.D.6a.ii) – Form 4.2‐1
For HCOC pre‐ and post‐development hydrologic calculation, the San Bernardino County
Stormwater Program requires the use of the Rational Method (San Bernardino County
Hydrology Manual Section D). Forms 4.2‐2 through Form 4.2‐5 calculate hydrologic variables
including runoff volume, time of concentration, and peak runoff from the project site pre‐ and
post‐development using the Hydrology Manual Rational Method approach. For projects greater
than 640 acres (1.0 mi2), the Rational Method and these forms should not be used. For such
projects, the Unit Hydrograph Method (San Bernardino County Hydrology Manual Section E)
shall be applied for hydrologic calculations for HCOC performance criteria.
Refer to Section 4 in the TGD for WQMP for detailed guidance and instructions.
Form 4.2‐1 LID BMP Performance Criteria for Design Capture Volume
(DA 1 DMA A)
1 Project area (ft2): 581,526
DA 1 DMA A (13.35 ac)
2 Imperviousness after applying
preventative site design practices
(Imp%): 95%
3 Runoff Coefficient (Rc): 0.807
Rc = 0.858(Imp%)3 ‐ 0.78(Imp%)2 +
0.774(Imp%) + 0.04 4 Determine 1‐hour rainfall depth for a 2‐year return period P2yr‐1hr (in): 0.516
http://hdsc.nws.noaa.gov/hdsc/pfds/sa/sca_pfds.html
5 Compute P6, Mean 6‐hr Precipitation (inches): 0.764
P6 = Item 4 *C1, where C1 is a function of site climatic region specified in Form 3‐1 Item 1
(Valley = 1.4807; Mountain = 1.909; Desert = 1.2371)
6 Drawdown Rate
Use 48 hours as the default condition. Selection and use of the 24 hour drawdown time condition is subject to
approval by the local jurisdiction. The necessary BMP footprint is a function of drawdown time. While shorter
drawdown times reduce the performance criteria for LID BMP design capture volume, the depth of water that can
be stored is also reduced.
24‐hrs
48‐hrs
7 Compute design capture volume, DCV (ft3): 47,269
DCV = 1/12 * [Item 1* Item 3 *Item 5 * C2], where C2 is a function of drawdown rate (24‐hr = 1.582; 48‐hr = 1.963)
Compute separate DCV for each outlet from the project site per schematic drawn in Form 3‐1 Item 2
1 Project area (ft2): 2,178
Driveway Runoff (0.05 ac)
2 Imperviousness after applying
preventative site design practices
(Imp%): 100%
3 Runoff Coefficient (Rc): 0.892
Rc = 0.858(Imp%)3 ‐ 0.78(Imp%)2 +
0.774(Imp%) + 0.04 4 Determine 1‐hour rainfall depth for a 2‐year return period P2yr‐1hr (in): 0.516
http://hdsc.nws.noaa.gov/hdsc/pfds/sa/sca_pfds.html
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐8
5 Compute P6, Mean 6‐hr Precipitation (inches): 0.764
P6 = Item 4 *C1, where C1 is a function of site climatic region specified in Form 3‐1 Item 1
(Valley = 1.4807; Mountain = 1.909; Desert = 1.2371)
6 Drawdown Rate
Use 48 hours as the default condition. Selection and use of the 24 hour drawdown time condition is subject to
approval by the local jurisdiction. The necessary BMP footprint is a function of drawdown time. While shorter
drawdown times reduce the performance criteria for LID BMP design capture volume, the depth of water that can
be stored is also reduced.
24‐hrs
48‐hrs
7 Compute design capture volume, DCV (ft3): 196
DCV = 1/12 * [Item 1* Item 3 *Item 5 * C2], where C2 is a function of drawdown rate (24‐hr = 1.582; 48‐hr = 1.963)
Compute separate DCV for each outlet from the project site per schematic drawn in Form 3‐1 Item 2
1 See Attachment B for detailed calculations. There is 0.05 acres of driveway area along the easterly
property line which will drain offsite. The driveway will be accounted for in the underground retention
system, even though it does not physically drain there.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐9
Form 4.2‐2 Summary of HCOC Assessment
Does project have the potential to cause or contribute to an HCOC in a downstream channel: Yes No
Go to: http://sbcounty.permitrack.com/WAP/
If “Yes”, then complete HCOC assessment of site hydrology for 2yr storm event using Forms 4.2‐3 through 4.2‐5 and insert results below (Forms
4.2‐3 through 4.2‐5 may be replaced by computer software analysis based on the San Bernardino County Hydrology Manual)
If “No,” then proceed to Section 4.3 Project Conformance Analysis
Condition Runoff Volume (ft
3) Time of Concentration (min) Peak Runoff (cfs)
Pre‐developed 1 n/a
Form 4.2‐3 Item 12
2 n/a
Form 4.2‐4 Item 13
3 n/a
Form 4.2‐5 Item 10
Post‐developed 4 n/a
Form 4.2‐3 Item 13
5 n/a
Form 4.2‐4 Item 14
6 n/a
Form 4.2‐5 Item 14
Difference
7 n/a
Item 4 – Item 1
8 n/a
Item 5 – Item 2
9 n/a
Item 6 – Item 3
Difference
(as % of pre‐developed)
10 n/a
Item 7 / Item 1
11 n/a
Item 8 / Item 2
12 n/a
Item 9 / Item 3
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐10 Form 4.2‐3 HCOC Assessment for Runoff Volume Compute weighted curve number for pre and post developed conditions Pre‐developed DA Add more columns if more than 4 DMA Post‐developed DA Add more columns if more than 4 DMA DMA A DMA B DMA C DMA D DMA A DMA B DMA C DMA D 1 Land Cover type 2 Hydrologic Soil Group (HSG) 3 DMA Area, ft2 sum of areas of DMA should equal area of DA 4 Curve Number (CN) Use Items 1 and 2 to select the appropriate CN from Appendix C‐2 of the TGD for WQMP 5 Pre‐Developed area‐weighted CN: 6 Post‐Developed area‐weighted CN: 7 Pre‐developed soil storage capacity, S (in): S = (1000 / Item 5) ‐ 10 8 Post‐developed soil storage capacity, S (in): S = (1000 / Item 6) ‐ 10 9 Initial abstraction, Ia (in): Ia = 0.2 * Item 7 10 Initial abstraction, Ia (in): Ia = 0.2 * Item 8 11 Precipitation for 2 yr, 24 hr storm (in): Go to: http://hdsc.nws.noaa.gov/hdsc/pfds/sa/sca_pfds.html 12 Pre‐developed Volume (ft3): Vpre =(1 / 12) * (Item sum of Item 3) * [(Item 11 – Item 9)^2 / ((Item 11 – Item 9 + Item 7) 13 Post‐developed Volume (ft3): Vpre =(1 / 12) * (Item sum of Item 3) * [(Item 11 – Item 10)^2 / ((Item 11 – Item 10 + Item 8) 14 Volume Reduction needed to meet HCOC Requirement, (ft3): VHCOC = (Item 13 * 0.95) – Item 12
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐11 Form 4.2‐4 HCOC Assessment for Time of Concentration Compute time of concentration for pre and post developed conditions for each DA (For projects using the Hydrology Manual complete the form below) Variables Pre‐developed DA Add more columns if more than 4 DMA Post‐developed DA Add more columns if more than 4 DMA DMA A DMA B DMA C DMA D DMA A DMA B DMA C DMA D 1 Length of flowpath (ft) Use Form 3‐2 Item 5 for pre‐developed condition 2 Change in elevation (ft) 3 Slope (ft/ft), So = Item 2 / Item 1 4 Land cover 5 Initial DMA Time of Concentration (min) Appendix C‐1 of the TGD for WQMP 6 Length of conveyance from DMA outlet to project site outlet (ft) May be zero if DMA outlet is at project site outlet 7 Cross‐sectional area of channel (ft2) 8 Wetted perimeter of channel (ft) 9 Manning’s roughness of channel (n) 10 Channel flow velocity (ft/sec) Vfps = (1.49 /Item 9) * (Item 7/Item 8)0.67 * (Item 3)0.5 11 Travel time to outlet (min) Tt = Item 6 / (Item 10 * 60) 12 Total time of concentration (min) Tc = Item 5 + Item 11 13 Pre‐developed time of concentration (min): Minimum of Item 12 pre‐developed DMA 14 Post‐developed time of concentration (min): Minimum of Item 12 post‐developed DMA 15 Additional time of concentration needed to meet HCOC requirement (min): TC‐HCOC = (Item 14 * 0.95) – Item 13
Water Quality Management Plan (WQMP) Santa Ana Avenue Industrial Building QR Birtcher Banana Ave. Owner LLC 4‐12 Form 4.2‐5 HCOC Assessment for Peak Runoff Compute peak runoff for pre and post developed conditions Variables Pre‐developed DA Add more columns if more than 3 DMA Post‐developed DA Add more columns if more than 3 DMA DMA A DMA B DMA C DMA A DMA B DMA C 1 Rainfall Intensity for storm duration equal to time of concentration Ipeak = 10^(LOG Form 4.2‐1 Item 4 ‐ 0.6 LOG Form 4.2‐4 Item 5 /60) 2 Drainage Area of each DMA (ft2) For DMA with outlet at project site outlet, include upstream DMA (Using example schematic in Form 3‐1, DMA A will include drainage from DMA C) 3 Ratio of pervious area to total area For DMA with outlet at project site outlet, include upstream DMA (Using example schematic in Form 3‐1, DMA A will include drainage from DMA C) 4 Pervious area infiltration rate (in/hr) Use pervious area CN and antecedent moisture condition with Appendix C‐3 of the TGD for WQMP 5 Maximum loss rate (in/hr) Fm = Item 3 * Item 4 Use area‐weighted Fm from DMA with outlet at project site outlet, include upstream DMA (Using example schematic in Form 3‐1, DMA A will include drainage from DMA C) 6 Peak Flow from DMA (cfs) Qp =Item 2 * 0.9 * (Item 1 ‐ Item 5) 7 Time of concentration adjustment factor for other DMA to site discharge point Form 4.2‐4 Item 12 DMA / Other DMA upstream of site discharge point (If ratio is greater than 1.0, then use maximum value of 1.0) DMA A n/a n/a DMA B n/a n/a DMA C n/a n/a 8 Pre‐developed Qp at Tc for DMA A: Qp = Item 6DMAA + [Item 6DMAB * (Item 1DMAA – Item 5DMAB) / (Item 1DMAB ‐ Item 5DMAB) * Item 7DMAA/2] + [Item 6DMAC * (Item 1DMAA ‐ Item 5DMAC) / (Item 1DMAC ‐ Item 5DMAC) * Item 7DMAA/3] 9 Pre‐developed Qp at Tc for DMA B: Qp = Item 6DMAB + [Item 6DMAA * (Item 1DMAB – Item 5DMAA) / (Item 1DMAA ‐ Item 5DMAA) * Item 7DMAB/1] + [Item 6DMAC * (Item 1DMAB ‐ Item 5DMAC) / (Item 1DMAC ‐ Item 5DMAC) * Item 7DMAB/3] 10 Pre‐developed Qp at Tc for DMA C: Qp = Item 6DMAC + [Item 6DMAA * (Item 1DMAC – Item 5DMAA) / (Item 1DMAA ‐ Item 5DMAA) * Item 7DMAC/1] + [Item 6DMAB * (Item 1DMAC ‐ Item 5DMAB) / (Item 1DMAB ‐ Item 5DMAB) * Item 7DMAC/2] 11 Peak runoff from pre‐developed condition confluence analysis (cfs): Maximum of Item 8, 9, and 10 12 Post‐developed Qp at Tc for DMA A: Same as Item 8 for post‐developed values 13 Post‐developed Qp at Tc for DMA B: Same as Item 9 for post‐developed values 14 Post‐developed Qp at Tc for DMA C: Same as Item 10 for post‐developed values 15 Peak runoff from post‐developed condition confluence analysis (cfs): Maximum of Item 12, 13, and 14 16 Peak runoff reduction needed to meet HCOC Requirement (cfs): Qp‐HCOC = (Item 14 * 0.95) – Item 11
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐13
4.3 Project Conformance Analysis
Complete the following forms for each project site DA to document that the proposed LID BMPs
conform to the project DCV developed to meet performance criteria specified in the MS4 Permit
(WQMP Template Section 4.2). For the LID DCV, the forms are ordered according to hierarchy of BMP
selection as required by the MS4 Permit (see Section 5.3.1 in the TGD for WQMP). The forms compute
the following for on‐site LID BMP:
Site Design and Hydrologic Source Controls (Form 4.3‐2)
Retention and Infiltration (Form 4.3‐3)
Harvested and Use (Form 4.3‐4) or
Biotreatment (Form 4.3‐5).
At the end of each form, additional fields facilitate the determination of the extent of mitigation
provided by the specific BMP category, allowing for use of the next category of BMP in the hierarchy, if
necessary.
The first step in the analysis, using Section 5.3.2.1 of the TGD for WQMP, is to complete Forms 4.3‐1 and
4.3‐3) to determine if retention and infiltration BMPs are infeasible for the project. For each feasibility
criterion in Form 4.3‐1, if the answer is “Yes,” provide all study findings that includes relevant
calculations, maps, data sources, etc. used to make the determination of infeasibility.
Next, complete Forms 4.3‐2 and 4.3‐4 to determine the feasibility of applicable HSC and harvest and use
BMPs, and, if their implementation is feasible, the extent of mitigation of the DCV.
If no site constraints exist that would limit the type of BMP to be implemented in a DA, evaluate the use
of combinations of LID BMPs, including all applicable HSC BMPs to maximize on‐site retention of the
DCV. If no combination of BMP can mitigate the entire DCV, implement the single BMP type, or
combination of BMP types, that maximizes on‐site retention of the DCV within the minimum effective
area.
If the combination of LID HSC, retention and infiltration, and harvest and use BMPs are unable to
mitigate the entire DCV, then biotreatment BMPs may be implemented by the project proponent. If
biotreatment BMPs are used, then they must be sized to provide sufficient capacity for effective
treatment of the remainder of the volume‐based performance criteria that cannot be achieved with LID
BMPs (TGD for WQMP Section 5.4.4.2). Under no circumstances shall any portion of the DCV be released
from the site without effective mitigation and/or treatment.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐14
Form 4.3‐1 Infiltration BMP Feasibility
Feasibility Criterion – Complete evaluation for each DA on the Project Site
1 Would infiltration BMP pose significant risk for groundwater related concerns? Yes No
Refer to Section 5.3.2.1 of the TGD for WQMP
If Yes, Provide basis: (attach)
2 Would installation of infiltration BMP significantly increase the risk of geotechnical hazards? Yes No
(Yes, if the answer to any of the following questions is yes, as established by a geotechnical expert):
The location is less than 50 feet away from slopes steeper than 15 percent
The location is less than eight feet from building foundations or an alternative setback.
A study certified by a geotechnical professional or an available watershed study determines that stormwater infiltration would result
in significantly increased risks of geotechnical hazards.
If Yes, Provide basis: (attach)
3 Would infiltration of runoff on a Project site violate downstream water rights? Yes No
If Yes, Provide basis: (attach)
4 Is proposed infiltration facility located on hydrologic soil group (HSG) D soils or does the site geotechnical investigation
indicate presence of soil characteristics, which support categorization as D soils? Yes No
If Yes, Provide basis: (attach)
5 Is the design infiltration rate, after accounting for safety factor of 2.0, below proposed facility less than 0.3 in/hr
(accounting for soil amendments)? Yes No
If Yes, Provide basis: (attach)
6 Would on‐site infiltration or reduction of runoff over pre‐developed conditions be partially or fully inconsistent with
watershed management strategies as defined in the WAP, or impair beneficial uses? Yes No
See Section 3.5 of the TGD for WQMP and WAP
If Yes, Provide basis: (attach)
7 Any answer from Item 1 through Item 3 is “Yes”: Yes No
If yes, infiltration of any volume is not feasible onsite. Proceed to Form 4.3‐4, Harvest and Use BMP. If no, then proceed to Item 9 below.
8 Any answer from Item 4 through Item 6 is “Yes”: Yes No
If yes, infiltration is permissible but is not required to be considered. Proceed to Form 4.3‐2, Hydrologic Source Control BMP.
If no, then proceed to Item 9, below.
9 All answers to Item 1 through Item 6 are “No”: Yes No
Infiltration of the full DCV is potentially feasible, LID infiltration BMP must be designed to infiltrate the full DCV to the MEP.
Proceed to Form 4.3‐2, Hydrologic Source Control BMP.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐15
4.3.1 Site Design Hydrologic Source Control BMP
Section XI.E. of the Permit emphasizes the use of LID preventative measures; and the use of LID HSC
BMPs reduces the portion of the DCV that must be addressed in downstream BMPs. Therefore, all
applicable HSC shall be provided except where they are mutually exclusive with each other, or with
other BMPs. Mutual exclusivity may result from overlapping BMP footprints such that either would be
potentially feasible by itself, but both could not be implemented. Please note that while there are no
numeric standards regarding the use of HSC, if a project cannot feasibly meet BMP sizing requirements
or cannot fully address HCOCs, feasibility of all applicable HSC must be part of demonstrating that the
BMP system has been designed to retain the maximum feasible portion of the DCV. Complete Form 4.3‐
2 to identify and calculate estimated retention volume from implementing site design HSC BMP. Refer to
Section 5.4.1 in the TGD for more detailed guidance.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐16
Form 4.3‐2 Site Design Hydrologic Source Control BMPs
1 Implementation of Impervious Area Dispersion BMP (i.e. routing runoff from impervious to pervious areas), excluding
impervious areas planned for routing to on‐lot infiltration BMP): Yes No
If yes, complete Items 2‐5; If no, proceed to Item 6
Variables
Aggregate impervious area dispersion with equal ratios of pervious to impervious;
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
2 Total impervious area draining to pervious area
3 Ratio of pervious area receiving runoff to impervious area
4 Retention volume achieved from impervious area dispersion (ft3)
V = Item2 * Item 3 * (0.5/12), assuming retention of 0.5 inches of runoff
5 Sum of retention volume achieved from impervious area dispersion (ft3): 0
Vretention = Sum of Item 4 for all BMPs
6 Implementation of Localized On‐lot Infiltration BMPs (e.g. on‐lot rain
gardens): Yes No
If yes, complete Items 7‐13 for aggregate of all on‐lot infiltration BMP in each DA;
If no, proceed to Item 14
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
7 Ponding surface area (ft2)
Ponding depth (ft)
9 Surface area of amended soil/gravel (ft2)
10 Average depth of amended soil/gravel (ft)
11 Average porosity of amended soil/gravel
12 Retention volume achieved from on‐lot infiltration (ft3)
Vretention = (Item 7 *Item 8) + (Item 9 * Item 10 * Item 11)
13 Runoff volume retention from on‐lot infiltration (ft3): 0
Vretention = Sum of Item 12 for all BMPs
14 Implementation of evapotranspiration BMP (green, brown, or blue
roofs): Yes No
If yes, complete Items 15‐20. If no, proceed to Item 21
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
15 Rooftop area planned for ET BMP (ft2)
16 Average wet season ET demand (in/day)
Use local values, typical ~ 0.1
17 Daily ET demand (ft3/day)
Item 15 * (Item 16 / 12)
18 Drawdown time (hrs)
Copy Item 6 in Form 4.2‐1
19 Retention Volume (ft3)
Vretention = Item 17 * (Item 18 / 24)
20 Runoff volume retention from evapotranspiration BMPs (ft3): 0
V = Sum of Item 19 for all BMPs
21 Implementation of Street Trees: Yes No
If yes, complete Items 20‐2. If no, proceed to Item 26
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
22 Number of Street Trees
23 Average canopy cover over impervious area (ft2)
24 Runoff volume retention from street trees (ft3)
Vretention = Item 22 * Item 23 * (0.05/12) assume runoff retention of 0.05 inches
25 Runoff volume retention from street tree BMPs (ft3): 0
Vretention = Sum of Item 24 for all BMPs
26 Implementation of residential rain barrels/cisterns: Yes No
If yes, complete Items 27‐28; If no, proceed to Item 30
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
27 Number of rain barrels/cisterns
28 Runoff volume retention from rain barrels/cisterns (ft3)
Vretention = Item 27 * 3
29 Runoff volume retention from residential rain barrels/Cisterns (ft3): 0
Vretention =Sum of Item 28 for all BMPs
30 Total Retention Volume from Site Design Hydrologic Source Control BMPs: 0
Sum of Items 5, 13, 20, 25 and 29
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐17
4.3.2 Infiltration BMPs
Use Form 4.3‐3 to compute on‐site retention of runoff from proposed retention and infiltration BMPs.
Volume retention estimates are sensitive to the percolation rate used, which determines the amount of
runoff that can be infiltrated within the specified drawdown time. The infiltration safety factor reduces
field measured percolation to account for potential inaccuracy associated with field measurements,
declining BMP performance over time, and compaction during construction. Appendix D of the TGD for
WQMP provides guidance on estimating an appropriate safety factor to use in Form 4.3‐3.
If site constraints limit the use of BMPs to a single type and implementation of retention and infiltration
BMPs mitigate no more than 40% of the DCV, then they are considered infeasible and the Project
Proponent may evaluate the effectiveness of BMPs lower in the LID hierarchy of use (Section 5.5.1 of
the TGD for WQMP)
If implementation of infiltrations BMPs is feasible as determined using Form 4.3‐1, then LID infiltration
BMPs shall be implemented to the MEP (section 4.1 of the TGD for WQMP).
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐18
Form 4.3‐3 Infiltration LID BMP (including underground BMPs)
(DA 1 DM A)
1 Remaining LID DCV not met by site design HSC BMP (ft3): 47,464
V = Form 4.2‐1 Item 7 ‐ Form 4.3‐2 Item 30
BMP Type
Use columns to the right to compute runoff volume retention from
proposed infiltration BMP (select BMP from Table 5‐4 in TGD for WQMP)
DA 1 DMA A n/a n/a
2 Infiltration rate of underlying soils (in/hr)
See Section 5.4.2 and Appendix D of the TGD for WQMP for minimum
requirements for assessment methods
19.8 n/a n/a
3 Infiltration safety factor
See TGD Section 5.4.2 and Appendix D 2.0 n/a n/a
4 Design percolation rate (in/hr)
Pdesign = Item 2 / Item 3 9.9 n/a n/a
5 Ponded water drawdown time (hr)
Copy Item 6 in Form 4.2‐1 24 n/a n/a
6 Maximum ponding depth (ft)
BMP specific, see Table 5‐4 of the TGD for WQMP for BMP design details
5.35’
(64.2”) n/a n/a
7 Ponding Depth (ft)
dBMP = Minimum of (1/12 * Item 4 * Item 5) or Item 6
5.35’
(64.2”) n/a n/a
8 Infiltrating surface area, SA (ft2)
The lesser of the area needed for BMP infiltration of full DCV or minimum
space requirements from Table 5‐7 of the TGD for WQMP
11,145 n/a n/a
9 Amended soil depth, dmedia (ft)
Only included in certain BMP types, see Table 5‐4 in the TGD for WQMP
for reference to BMP design details
n/a n/a n/a
10 Amended soil porosity n/a n/a n/a
11 Gravel depth, dmedia (ft)
Only included in certain BMP types, see Table 5‐4 of the TGD for WQMP
for BMP design details
3’
(36”) n/a n/a
12 Gravel porosity 0.40 n/a n/a
13 Duration of storm as basin is filling (hrs)
Typical ~ 3hrs 3 n/a n/a
14 Above Ground Retention Volume (ft3)
Vretention = Item 8 * [Item7 + (Item 9 retention * Item 10) + (Item 11 * Item
12) + (Item 13 * (Item 4 / 12))]
n/a n/a n/a
15 Underground Retention Volume (ft3)
Volume determined using manufacturer’s specifications and calculations
47,593
(see Attach. B
for detailed
calculations)
n/a n/a
16 Total Retention Volume from LID Infiltration BMPs (ft3): 47,593
(Sum of Items 14 and 15 for all infiltration BMP included in plan)
17 Fraction of DCV achieved with infiltration BMP: 100%
Retention% = Item 16 / Form 4.2‐1 Item 7
18 Is full LID DCV retained on‐site with combination of hydrologic source control and LID retention and infiltration BMPs?
Yes No
If yes, demonstrate conformance using Form 4.3‐10; If no, then reduce Item 3, Factor of Safety to 2.0 and increase Item 8, Infiltrating Surface
Area, such that the portion of the site area used for retention and infiltration BMPs equals or exceeds the minimum effective area thresholds
(Table 5‐7 of the TGD for WQMP) for the applicable category of development and repeat all above calculations.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐19
4.3.3 Harvest and Use BMP
Harvest and use BMP may be considered if the full LID DCV cannot be met by maximizing infiltration
BMPs. Use Form 4.3‐4 to compute on‐site retention of runoff from proposed harvest and use BMPs.
Volume retention estimates for harvest and use BMPs are sensitive to the on‐site demand for captured
stormwater. Since irrigation water demand is low in the wet season, when most rainfall events occur in
San Bernardino County, the volume of water that can be used within a specified drawdown period is
relatively low. The bottom portion of Form 4.3‐4 facilitates the necessary computations to show
infeasibility if a minimum incremental benefit of 40 percent of the LID DCV would not be achievable with
MEP implementation of on‐site harvest and use of stormwater (Section 5.5.4 of the TGD for WQMP).
Form 4.3‐4 Harvest and Use BMPs
1 Remaining LID DCV not met by site design HSC or infiltration BMP (ft3):
Vunmet = Form 4.2‐1 Item 7 ‐ Form 4.3‐2 Item 30 – Form 4.3‐3 Item 16
BMP Type(s)
Compute runoff volume retention from proposed harvest and use BMP (Select
BMPs from Table 5‐4 of the TGD for WQMP)
BMP Type and
DA
BMP Type and
DA
BMP Type and
DA
2 Describe cistern or runoff detention facility
3 Storage volume for proposed detention type (ft3)
Volume of cistern
4 Landscaped area planned for use of harvested stormwater (ft2)
5 Average wet season daily irrigation demand (in/day)
Use local values, typical ~ 0.1 in/day
6 Daily water demand (ft3/day)
Item 4 * (Item 5 / 12)
7 Drawdown time (hrs)
Copy Item 6 from Form 4.2‐1
8 Retention Volume (ft3)
Vretention = Minimum of (Item 3) or (Item 6 * (Item 7 / 24))
9 Total Retention Volume (ft3) from Harvest and Use BMP:
Sum of Item 8 for all harvest and use BMP included in plan
10 Is the full DCV retained with a combination of LID HSC, retention and infiltration, and harvest and use BMPs? Yes No
If yes, demonstrate conformance using Form 4.3‐10. If no, then re‐evaluate combinations of all LID BMP and optimize their implementation such
that the maximum portion of the DCV is retained on‐site (using a single BMP type or combination of BMP types). If the full DCV cannot be
mitigated after this optimization process, proceed to Section 4.3.4.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐20
4.3.4 Biotreatment BMP
Biotreatment BMPs may be considered if the full LID DCV cannot be met by maximizing retention and
infiltration, and harvest and use BMPs. A key consideration when using biotreatment BMP is the
effectiveness of the proposed BMP in addressing the pollutants of concern for the project (see Table 5‐5
of the TGD for WQMP).
Use Form 4.3‐5 to summarize the potential for volume based and/or flow based biotreatment options to
biotreat the remaining unmet LID DCV. Biotreatment computations are included as follows:
Use Form 4.3‐6 to compute biotreatment in small volume based biotreatment BMP (e.g.
bioretention w/underdrains);
Use Form 4.3‐7 to compute biotreatment in large volume based biotreatment BMP (e.g.
constructed wetlands);
Use Form 4.3‐8 to compute sizing criteria for flow‐based biotreatment BMP (e.g. bioswales)
Form 4.3‐5 Selection and Evaluation of Biotreatment BMP
1 Remaining LID DCV not met by site design HSC,
infiltration, or harvest and use BMP for potential
biotreatment (ft3):
Form 4.2‐1 Item 7 – Form 4.3‐2 Item 30 – Form 4.3‐3 Item 16‐ Form
4.3‐4 Item 9
List pollutants of concern
Copy from Form 2.3‐1
2 Biotreatment BMP Selected
(Select biotreatment BMP(s) necessary to
ensure all pollutants of concern are
addressed through Unit Operations and
Processes, described in Table 5‐5 of the TGD
for WQMP)
Volume‐based biotreatment
Use Forms 4.3‐6 and 4.3‐7 to compute
treated volume
Flow‐based biotreatment
Use Form 4.3‐8 to compute treated volume
Bioretention with underdrain
Planter box with underdrain
Constructed wetlands
Wet extended detention
Dry extended detention
Vegetated swale
Vegetated filter strip
Proprietary biotreatment
3 Volume biotreated in volume based
biotreatment BMP (ft3):
Form 4.3‐6 Item 15 + Form 4.3‐7 Item 13
4 Compute remaining LID DCV with
implementation of volume based
biotreatment BMP (ft3):
Item 1 – Item 3
5 Remaining fraction of LID DCV for
sizing flow based biotreatment BMP: %
Item 4 / Item 1
6 Flow‐based biotreatment BMP capacity provided (cfs):
Use Figure 5‐2 of the TGD for WQMP to determine flow capacity required to provide biotreatment of remaining percentage of unmet LID DCV
(Item 5), for the project’s precipitation zone (Form 3‐1 Item 1)
7 Metrics for MEP determination:
Provided a WQMP with the portion of site area used for suite of LID BMP equal to minimum thresholds in
Table 5‐7 of the TGD for WQMP for the proposed category of development:
If maximized on‐site retention BMPs is feasible for partial capture, then LID BMP implementation must be optimized to retain and
infiltrate the maximum portion of the DCV possible within the prescribed minimum effective area. The remaining portion of the DCV
shall then be mitigated using biotreatment BMP.
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐21
Form 4.3‐6 Volume Based Biotreatment – Bioretention and Planter
Boxes with Underdrains
BMP Type(s)
Compute runoff volume retention from proposed harvest and use BMP (Select BMPs from Table
5‐4 of the TGD for WQMP)
BMP Type
and DA
BMP Type
and DA
BMP Type
and DA
1 Pollutants addressed with BMP
List all pollutant of concern that will be effectively reduced through specific Unit Operations and
Processes described in Table 5‐5 of the TGD for WQMP
2 Amended soil infiltration rate
Typical ~ 5.0 in/hr
3 Amended soil infiltration safety factor
Typical ~ 2.0
4 Amended soil design percolation rate (in/hr)
Pdesign = Item 2 / Item 3
5 Ponded water drawdown time (hr)
Copy Item 6 from Form 4.2‐1
6 Maximum ponding depth (ft)
See Table 5‐6 of the TGD for WQMP for reference to BMP design details
7 Ponding Depth (ft)
dBMP = Minimum of (1/12 * Item 4 * Item 5) or Item 6
8 Amended soil surface area (ft2)
9 Amended soil depth (ft)
See Table 5‐6 of the TGD for WQMP for reference to BMP design details
10 Amended soil porosity, n
11 Gravel depth (ft)
See Table 5‐6 of the TGD for WQMP for reference to BMP design details
12 Gravel porosity, n
13 Duration of storm as basin is filling (hrs)
Typical ~ 3hrs
14 Biotreated Volume (ft3)
Vbiotreated = Item 8 * [(Item 7/2) + (Item 9 * Item 10) +(Item 11 * Item 12) + (Item 13 * (Item 4 /
12))]
15 Total biotreated volume from bioretention and/or planter box with underdrains BMP:
Sum of Item 14 for all volume‐based BMPs included in this form
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐22
Form 4.3‐7 Volume Based Biotreatment – Constructed Wetlands and
Extended Detention
Biotreatment BMP Type
Constructed wetlands, extended wet detention, extended dry
detention, or other comparable proprietary BMP. If BMP includes
multiple modules (e.g. forebay and main basin), provide separate
estimates for storage and pollutants treated in each module.
BMP Type and DA BMP Type and DA BMP Type and DA
Forebay Basin Forebay Basin Forebay Basin
1 Pollutants addressed with BMP forebay and basin
List all pollutant of concern that will be effectively reduced
through specific Unit Operations and Processes described in
Table 5‐5 of the TGD for WQMP
2 Bottom width (ft)
3 Bottom length (ft)
4 Bottom area (ft2)
Abottom = Item 2 * Item 3
5 Side slope (ft/ft)
6 Depth of storage (ft)
7 Water surface area (ft2)
Asurface = (Item 2 + (2 * Item 5 * Item 6)) * (Item 3 + (2 * Item 5 *
Item 6))
8 Storage volume (ft3)
For BMP with a forebay, ensure fraction of total storage is within
ranges specified in BMP specific fact sheets, see Table 5‐6 of the
TGD for WQMP for reference to BMP design details V =Item 6 / 3
* [Item 4 + Item 7 + (Item 4 * Item 7)0.5]
9 Drawdown Time (hrs)
Copy Item 6 from Form 2.1
10 Outflow rate (cfs)
QBMP = (Item 8forebay + Item 8basin) / (Item 9 * 3600)
11 Duration of design storm event (hrs)
12 Biotreated Volume (ft3)
Vbiotreated = (Item 8forebay + Item 8basin) +( Item 10 * Item 11 * 3600)
13 Total biotreated volume from constructed wetlands, extended dry detention, or extended wet detention:
(Sum of Item 12 for all BMP included in plan)
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐23
Form 4.3‐8 Flow Based Biotreatment
Biotreatment BMP Type
Vegetated swale, vegetated filter strip, or other comparable proprietary BMP
BMP Type
and DA
BMP Type
and DA
BMP Type
and DA
1 Pollutants addressed with BMP
List all pollutant of concern that will be effectively reduced through specific Unit Operations and
Processes described in TGD Table 5‐5
2 Flow depth for water quality treatment (ft)
BMP specific, see Table 5‐6 of the TGD for WQMP for reference to BMP design details
3 Bed slope (ft/ft)
BMP specific, see Table 5‐6 of the TGD for WQMP for reference to BMP design details
4 Manning's roughness coefficient
5 Bottom width (ft)
bw = (Form 4.3‐5 Item 6 * Item 4) / (1.49 * Item 21.67 * Item 30.5)
6 Side Slope (ft/ft)
BMP specific, see Table 5‐6 of the TGD for WQMP for reference to BMP design details
7 Cross sectional area (ft2)
A = (Item 5 * Item 2) + (Item 6 * Item 2^2)
8 Water quality flow velocity (ft/sec)
V = Form 4.3‐5 Item 6 / Item 7
9 Hydraulic residence time (min)
Pollutant specific, see Table 5‐6 of the TGD for WQMP for reference to BMP design details
10 Length of flow based BMP (ft)
L = Item 8 * Item 9 * 60
11 Water surface area at water quality flow depth (ft2)
SAtop = (Item 5 + (2 * Item 2 * Item 6)) * Item 10
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐24
4.3.5 Conformance Summary
Complete Form 4.3‐9 to demonstrate how on‐site LID DCV is met with proposed site design hydrologic
source control, infiltration, harvest and use, and/or biotreatment BMP. The bottom line of the form is
used to describe the basis for infeasibility determination for on‐site LID BMP to achieve full LID DCV, and
provides methods for computing remaining volume to be addressed in an alternative compliance plan. If
the project has more than one outlet, then complete additional versions of this form for each outlet.
Form 4.3‐9 Conformance Summary and Alternative Compliance
Volume Estimate (DA 1 DMA A)
1 Total LID DCV for the Project (ft3): 47,464
Copy Item 7 in Form 4.2‐1
2 On‐site retention with site design hydrologic source control LID BMP (ft3): 0
Copy Item 30 in Form 4.3‐2
3 On‐site retention with LID infiltration BMP (ft3): 47,593
Copy Item 16 in Form 4.3‐3
4 On‐site retention with LID harvest and use BMP (ft3): 0
Copy Item 9 in Form 4.3‐4
5 On‐site biotreatment with volume based biotreatment BMP (ft3): 0
Copy Item 3 in Form 4.3‐5
6 Flow capacity provided by flow based biotreatment BMP (cfs): 0
Copy Item 6 in Form 4.3‐5
7 LID BMP performance criteria are achieved if answer to any of the following is “Yes”:
Full retention of LID DCV with site design HSC, infiltration, or harvest and use BMP: Yes No
If yes, sum of Items 2, 3, and 4 is greater than Item 1
Combination of on‐site retention BMPs for a portion of the LID DCV and volume‐based biotreatment BMP that
address all pollutants of concern for the remaining LID DCV: Yes No
If yes, a) sum of Items 2, 3, 4, and 5 is greater than Item 1, and Items 2, 3 and 4 are maximized; or b) Item 6 is greater than Form 4.3‐‐
5 Item 6 and Items 2, 3 and 4 are maximized
On‐site retention and infiltration is determined to be infeasible and biotreatment BMP provide biotreatment for all
pollutants of concern for full LID DCV: Yes No
If yes, Form 4.3‐1 Items 7 and 8 were both checked yes
8 If the LID DCV is not achieved by any of these means, then the project may be allowed to develop an alternative compliance
plan. Check box that describes the scenario which caused the need for alternative compliance:
Combination of HSC, retention and infiltration, harvest and use, and biotreatment BMPs provide less than full
LID DCV capture.
Checked yes for Form 4.3‐5 Item 7, Item 6 is zero, and sum of Items 2, 3, 4, and 5 is less than Item 1. If so, apply water quality credits
and calculate volume for alternative compliance, Valt = (Item 1 – Item 2 – Item 3 – Item 4 – Item 5) * (100 ‐ Form 2.4‐1 Item 2)%
An approved Watershed Action Plan (WAP) demonstrates that water quality and hydrologic impacts of
urbanization are more effective when managed in at an off‐site facility.
Attach appropriate WAP section, including technical documentation, showing effectiveness comparisons for the project site and
regional watershed
Water Quality Management Plan (WQMP)
Santa Ana Avenue Industrial Building
QR Birtcher Banana Ave. Owner LLC 4‐25
4.3.6 Hydromodification Control BMP
Use Form 4.3‐10 to compute the remaining runoff volume retention, after LID BMP are implemented,
needed to address HCOC, and the increase in time of concentration and decrease in peak runoff
necessary to meet targets for protection of waterbodies with a potential HCOC. Describe
hydromodification control BMP that address HCOC, which may include off‐site BMP and/or in‐stream
controls. Section 5.6 of the TGD for WQMP provides additional details on selection and evaluation of
hydromodification control BMP.
Form 4.3‐10 Hydromodification Control BMPs
1 Volume reduction needed for
HCOC performance criteria (ft3):
(Form 4.2‐2 Item 4 * 0.95) – Form 4.2‐2
Item 1
2 On‐site retention with site design hydrologic source control, infiltration, and harvest
and use LID BMP (ft3):
Sum of Form 4.3‐9 Items 2, 3, and 4. Evaluate option to increase implementation of on‐site
retention in Forms 4.3‐2, 4.3‐3, and 4.3‐4 in excess of LID DCV toward achieving HCOC volume
reduction
3 Remaining volume for HCOC
volume capture (ft3):
Item 1 – Item 2
4 Volume capture provided by incorporating additional on‐site or off‐site retention
BMPs (ft3):
Existing downstream BMP may be used to demonstrate additional volume capture (if so, attach to
this WQMP a hydrologic analysis showing how the additional volume would be retained during a 2‐
yr storm event for the regional watershed)
5 If Item 4 is less than Item 3, incorporate in‐stream controls on downstream waterbody segment to prevent impacts due to
hydromodification