HomeMy WebLinkAboutCT 07-04; BRESSI RANCH MEDICAL PLAZA; STORM WATER MANAGEMENT PLAN; 2008-05-01I"F hu h..
E N 6 I N [ E R I N 6
Bressi Ranch Medical Plaza
Storm Water Management Plan
Response to Comments
RECEIVED
PREPARED FOR: City of Carlsbad
MAY 2 8 28 PREPARED BY: Joe Kuhn, Fuscoe Engineering, Inc.
DATE: May, 2008 ENGINEERING
DEPARTMENT
This technical memorandum provides responses to the comments provided by RBF Consulting, on
behalf of the City of Carlsbad concerning the SWMP for Bressi Ranch Medical Plaza. The
comments are marked as Plan Check 3 on the front cover.
The comment letter provides an itemized comment discussion for each comment raised in Plan
Check 3.
Response to Specific Comment (SWMP)
Issue Number 1: Per the City SUSMP Section 2.3.2.3 Item 4, you must address the 2 & 10-year 6
and 24 hour storm events.
Per conversations with Rich Lucera in the RBF Consulting Carlsbad Office, the SWMP needed to
examine 2 and 10 year flows per City of Carlsbad SUSMP requirements. The SWMP now includes
calculations located in Appendix 5 showing the 2 & 1 0-year site flows taking into account the
biofiltration basins. The calculations show runoff rates and volumes from each basin, as well as
travel times in order to calculate a reduction in the 2 & 1 0-year flows as compared to a "no
detention" condition. This results in a decrease in site flows as noted on Page 13 of the SWMP.
This calculation was provided to RBF via email and it was deemed as adequate per our phone
conversation on May 13.
Any questions please contact at (858) 554-1500
Thanks,
Joe Kuhn
Water Quality Scientist
Fuscoe Engineering
6390 GREENWICH DR., STE. 170, SAN DIEGO, CA 92122 TEL 858.554.1500 FAX 858.597.0335 WWW.FUSCOE.COM
STORMWATER
MANAGEMENT PLAN
. . .
T.
Ui
Bressi Ranch Medical Plaza
City of carlsbad, CA
May2008
Prepared For: Bressi Ranch Medical Plaza
Prepared By: Paul D. Haaland, P.E.
Job Number: 2591.02A
W FUSCOE
-- ENGINEERING 1 I Ull Il,(I. Ifl,!.II(, p
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I
STORM WATER MANAGEMENT PLAN MAY 2008
STORM WATER MANAGEMENT PLAN
Bressi Ranch Medical Plaza
Town Garden Road and Metropolitan St
Carlsbad, CA 92009
Prepared By
Fuscoe Engineering
6390 Greenwich Dr. Ste 170
San Diego, CA 92122
(858) 554-1500
For
Bressi Ranch Medical Plaza LLC
1280 Bison Ave # B9-609
Newport Beach, CA 92660
May 2008
BRESS! RANCH MEDICAL PLAZA TABLE OF CONTENTS
STORM WATER MANAGEMENT PLAN MAY 2008
Ir
TABLE OF CONTENTS
1.0 INTRODUCTION ..........................................................................................................5
1.1 PROJECT DESCRIPTION .................................................................................................5
1.2 PROPOSED LAND USE, BUILDING, AND PARKING SUMMARY..........................................7
1.3 HYDROLOGIC UNIT CONTRIBUTION.............................................................................8
2.0 WATER QUALITY ENVIRONMENT...................................................................................9
2.1 BENIFICIAL USES ............................................................................................................9
2.1 .1 INLAND SURFACE WATERS/COASTAL RECEIVING WATERS ....................................10
+- excepted from Municipal .................................................................................................. 10
2.1.2 303(D) STATUS ..................................................................................................... 10
2.2 HYDROLOGY ...............................................................................................................11
2.2.1 PRE CONSTRUCTION CONDITIONS AND FLOW..................................................12
2.2.2 POST CONSTRUCTION CONDITIONS AND FLOW...............................................12
2.3 POTENTIAL POLLUTANTS .............................................................................................. 1 4
2.4 SOIL CHARACTERISTICS ...............................................................................................16
3.0 CONSTRUCTION BMPs...............................................................................................17
3.1 CONSTRUCTION PHASE POTENTIAL POLLUTANTS .......................................................17
3.2 CONSTRUCTION PHASE BMPS ...................................................................................... 1 7
4.0 POST CONSTRUCTION BMPs ...................................................................................... 1 9
4.1 POST CONSTRUCTION BMPs.......................................................................................19
4.1.1 SITE DESIGN BMPs ................................................................................................19
LIDSITE DESIGN BMPS ........................................................................................................20
4.1.2 SOURCE CONTROL BMPs .....................................................................................20
4.1.3 TREATMENT CONTROL BMPs ................................................................................21
CONTROL 1: BIORETENTION- MODIFIED SAND FILTER TRENCHES......................................24
5.0 MAINTENANCE ..........................................................................................................27
5.1 POST CONSTRUCTION BMPs.......................................................................................27
5.2.1 BIORETENTION- MODIFIED SAND FILTER TRENCHES ............................................28
5.3 FISCAL RESOURCES .....................................................................................................28
6.0 SUMMARY AND CONCLUSIONS .................................................................................31
ANNUAL CERTIFICATION OF BMP MAINTENANCE ..............................................................31
LONG-TERM FUNDING FOR BMP MAINTENANCE ...............................................................31
ACCESS EASEMENT FOR CITY INSPECTION.........................................................................31
S
BRESSI RANCH MEDICAL PLAZA TABLE OF CONTENTS
STORM WATER MANAGEMENT PLAN MAY 2008
7.0 APPENDICES ..............................................................................................................32
APPENDIX 1 .........................................................................RUNOFF COEFFICENT REFERENCES
APPENDIX 2 ..............................................................NOTICE OF TRANSFER OF RESPONSIBILITY
APPENDIX 3 ............................................................................BMP EDUCATIONAL FACT SHEETS
APPENDIX 4 ...........................................................TREATMENT CONTROL BMP SPECIFCATIONS
APPENDIX5 .........................................................................................PROPOSED HYDROLOGY
APPENDIX 6.................................................................................BMP MAINTENANCE
BRESSI RANCH MEDICAL PLAZA TABLE OF CONTENTS
STORM WATER MANAGEMENT PLAN MAY 2008
>ROAD I
AR PALO
I MELROSE
DRIVE
.POINSETTIA
LANE
EL FUERTE
STREET
PROJECT SITE
VICINITY MAP
NOT TO SCALE
Figure 1 Vicinity Map
1.0 INTRODUCTION
The Storm Water Management Plan (SWMP) is required per the City of Carlsbad Storm Water
Standards Manual under the Regional Water Quality Control Board Order CAS01 08758. The purpose
of this SWMP is to address the water quality impacts from the proposed Bressi Ranch Medical Plaza
project (herein referred to as project). California Stormwater Quality Association (CASQA) BMPs, as
well as those outlined in the Carlsbad Storm Water Standards Manual will be used to provide o long-
term solution to water quality onsite. This SWMP is subject to revisions as needed by the engineer.
1.1 PROJECT DESCRIPTION
This 1 .95 acre lot is at the southwest corner of the intersection of Town Garden Road and Metropolitan St. in
Carlsbad, CA. The Bressi Ranch Medical Plaza project will consist of a 9,630 sq ft building containing
medical office condominiums, a surface parking lot, as well as related hardscope, utility, water quality, and
landscape improvements. The existing and proposed zoning of the development consists of planned industrial
(current), and office (proposed).
The project site is Lot 1 of the Bressi Ranch Industrial Area, located in Carlsbad, CA. Bordered by El Camino
Real to the west, open space to the south, Metropolitan St. to the east, and Town Garden Road to the north.
Concurrent to this project, there are mass graded and currently developing areas to the north and east. The
immediate surrounding area is comprised primarily of commercial, industrial, and open space areas. 1-5 is
located approximately 3 miles to the west. Site runoff will enter water quality treatment areas, and
S
BRESSI RANCH MEDICAL PLAZA 5 INTRODUCTION
STORM WATER MANAGEMENT PLAN MAY 2008
subsequently be routed toward proposed storm drain facilities prior to reaching the existing 24' RCP storm
drain on Town Garden Road. More information concerning storm water flows is located in Section 2.2.
The present condition of the site consists of mass graded land sloping to the northeast at approximately
7.0%. A desilting basin is located in the eastern portion of the site for the purpose of protecting water
quality during the rough grade condition. Flow originating onsite sheet flows to the basin and is
discharged through via a 36" CMP riser or emergency spillway. Flow is conveyed toward a 24" storm
drain stub which ties into the backbone 24' RCP storm drain on Town Garden Road. During
construction, the desilting basin will be removed, and replaced by permanent water quality features.
Flow originating from the vegetated hillside south of the site primarily flows through an existing ditch to
the east. There are no other areas of potential run on surrounding the project site.
PRIORITY (PROJECT CATAGORIES
Detached Res. Dev. 10+ Units
Commercial Development + 1 acre
Heavy Industry
Industrial Development + 1 acre
Automotive Repair Shops
Restaurants
Hillside Developments > 5000 sq ft.
Project Discharging to Receiving Waters
within Water Quality Sensitive Areas over
2500 sq ft or increase imperviousness over
10% of existing condition.
Parking Lots > 5,000 sq ft or > 15 spaces 7
Streets, roads, highways, freeways, create
new paved surface > 5000 sq ft.
f
Retail Gasoline Outlets 5,000 sq ft or more
or_prolect_1 00 or more _vehicles _per_day.
BRESS! RANCH MEDICAL PLAZA 6 - INTRODUCTION
STORM WATER MANAGEMENT PLAN MAY 2008
1.2 PROPOSED LAND USE, BUILDING, AND PARKING SUMMARY
The proposed project area is comprised of a medical condominium building, parking lot, associated
hardscape, water quality treatment areas, and landscaping.
DEVELOPMENT SUMMARY
BUILDING . SIZE (SF) FEATURES
Office Building 9,967 2 Levels
Water Quality Treatment
Areas J
2,448 Water Quality Treatment
Assorted Landscaping! 16,100 Site Landscaping Other_Softscape*
Parking Lots/Drive Aisles 35,753 100 Spaces
Assorted Hardscape 20,708 Sidewalks, Pavement, Entryway
* A majority of the sofiscape area is located to the west of the building outside the proposed
development area. These areas are not included in the C factor calculation provided in Section 2.2.
BRESS! RANCH MEDICAL PLAZA INTRODUCTION
STORM WATER MANAGEMENT PLAN MAY 2008
1.3 HYDROLOGIC UNIT CONTRIBUTION
The Bressi Ranch Medical Plaza project is located within the Batiquitos Hydraulic Sub-Area, within the
San Marcos Hydraulic Area, within the Carlsbad Hydrologic Unit. The corresponding number
designation is 904.51.
The Carlsbad Hydrologic Unit is approximately 210 square miles in area extending from the
headwaters above Lake Wolhford in the east to the Pacific Ocean in the west, and from Vista and
Oceanside in the north to Solana Beach, Escondido, and the community of Rancho Santa Fe to the
south. The cities of Carlsbad, San Marcos, and Encinitas are entirely within this HU. There are
numerous important surface hydrologic features within the Carlsbad HU including four unique coastal
lagoons, three major creeks, and two large water storage reservoirs. The HU contains four major,
roughly parallel hydrologic areas. From north to south they are the Buena Vista (901 .2), the Agua
Hedionda (904.3), the Batiquitos (904.5), and the San Elijo (904.6) HAs. Two smaller HAs, the Loma
Alta (904.1) and the Canyon de las Encinas (904.4) are also within the Carlsbad HU.
Flows from the existing project area drains toward existing 24' RCP storm drain heading northeast from
the project site. The storm drain pipe travels in this direction for approximately 300' until reaching a
junction structure and flowing southeast into the open space canyon. The runoff discharges onto an
existing concrete energy dissipater and 5' by 14' rip rap pad prior to its release down the canyon.
Site storm water runoff is conveyed through the canyon, under Carrillo Way, and through the unnamed
tributary transversing the La Costa Resort Golf Course. Flows join San Marcos Creek on the southern
portion of the La Costa property, just north of La Costa Ave. San Marcos Creek empties into the
Batiquitos Lagoon approximately 0.37 miles west of the Resort. The Batiquitos Lagoon is a large, 2.5
mile long lagoon which outlets at the Pacific Ocean north of La Costa Ave, in Carlsbad, CA.
San Marcos Creek has 303(d) listed impairments which are listed in Section 2.1.2. There are no
TMDLs for any of the receiving waters from the proposed project site.
BRESSI RANCH MEDICAL PLAZA 8 INTRODUCTION
STORM WATER MANAGEMENT PLAN MAY 2008
2.0 WATER QUALITY ENVIRONMENT
2.1 BENIFICIAL USES
The beneficial uses for the hydrologic unit are included in Tables 1 1 and 1 .2. These tables have been
extracted from the "Water Quality Control Plan for the San Diego Basin (9)," dated September 8,
1994.
MUN- Municipal and Domestic Supply: Includes uses of water for community, military, or individual
water supply systems including, but not limited to, drinking water supply.
AGR- Agricultural Supply: Includes uses of water for farming, horticulture, or ranching including, but
not limited to , irrigation, stock watering, or support of vegetation for range grazing.
WARM-- Warm Freshwater Habitat: Includes uses of water that support warm water ecosystems
including, but not limited to, preservation or enhancement of aquatic habitats, vegetation, fish or
wildlife, including invertebrates.
AQUA- Includes the uses of water for aquaculture or mariculture operations including, but not limited
to, propagation, cultivation, maintenance, or harvesting of aquatic plants and animals for human
consumption or bait purposes.
COMM- includes the uses of water for commercial or recreational collection of fish, shellfish, or other
organisms, including, but not limited to, uses involving organisms intended for human consumption or
bait purposes.
BIOL- Includes uses of water that support designated areas or habitats, such as refuges, parks,
sanctuaries, ecological reserves, or Areas of Special Biological Significance (ASBS) where the
preservation or enhancement of natural resources requires special protection.
EST- Includes uses of water that support estuarine ecosystems, including but not limited to, preservation
or enhancement of estuarine habitats, vegetation, fish, shellfish, or wildlife (e.g. estuarine mammals,
waterfowl, or shorebirds.)
RARE- Includes uses of water that support habitats necessary, at least in part, for the survival and
successful maintenance of plant or animal species, established under state or federal law as rare,
threatened or endangered.
SPWN- Includes uses of water that support that support high quality aquatic habitats suitable for
reproduction and early development of fish. This use is applicable for only the protection of
anadromous fish.
SHELL- Includes uses of water that support habitats suitable for the collection of filter feeding shellfish
(e.g. clams, oysters and mussels) for human consumption, commercial, or sport purposes.
MIGR- Includes uses of water that support habitats necessary for migration, acclimatization between
fresh and salt water, or other temporary activities by aquatic organisms such as anadromous fish.
MAR- Includes uses of water that support marine ecosystems including, but not limited to, preservation
or enhancement of marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g. marine
mammals, shorebirds.)
IND - Includes uses of water for industrial activities that do not depend primarily on water quality
including, but not limited to, mining, cooling water supply, hydraulic conveyance, gravel washing, fire
protection, or oil well re-pressurization.
REC1 - Contact Recreation: Includes uses of water for recreational activities involving body contact with
water, where ingestion of water is reasonably possible. These uses include, but are not limited to,
swimming, wading, water-skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use
of natural hot springs.
REC2 - Non-Contact Recreation: Includes the uses of water for recreation involving proximity to water,
but not normally involving body contact with water, where ingestion of water is reasonably possible.
BRESSI RANCH MEDICAL PLAZA 9 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
These uses include, but are not limited to, picnicking, sunbathing, hiking, camping, boating, tide pool
and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above
activities.
WILD - Wildlife Habitat: Includes uses of water that support terrestrial ecosystems including, but not
limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife, (e.g., mammals,
birds, reptiles, amphibians, invertebrates), or wildlife water and food sources.
2.1.1 INLAND SURFACE WATERS/COASTAL RECEIVING WATERS
Inland surface waters have the following beneficial uses as shown:
o - Potential Beneficial Use
- Existing Beneficial Use
+- excepted from Municipal
2.1.2 303(D) STATUS
According to the California 2006 303d list published by the State Water Resources Control Board
(SWRCB), San Marcos Creek, is a beneficial impaired water bodies. San Marcos Creek is impaired for
DDE, Phosphorus, and Sediment Toxicity.
The point of discharge into the San Marcos Creek is approximately 2.4 miles downstream of the project
site. The Pacific Ocean Shoreline at the Batiquitos Lagoon outlet is not impaired according to the 2006
303(d) list.
BRESS! RANCH MEDICAL PLAZA 10 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
The causes of wafer quality problems are as follows according to the 2006 303(d) list: San Marcos
Creek: Source Unknown.
2.2 HYDROLOGY
City of Carlsbad requirements state that where downstream conditions of concern have been identified,
the drainage study shall establish that pre-project hydrologic conditions that minimize impacts on those
downstream conditions of concern would be either improved or maintained by the proposed project.
The existing project site consists of 1 drainage area sheet flowing into a large desilting basin located in
the northeast corner of the project site. Flows exit the basin via the 36' CMP riser or emergency
spillway, and are conveyed toward the stub 24" RCP which connects to the backbone storm drain on
Town Garden Road.
The proposed site consists of an extremely similar drainage condition as the existing condition. The site
is comprised of drainage areas which discharge to proposed onsite storm drain inlets. These inlets
convey all flow to the northeast corner of the project site; toward the existing 24" RCP on Town Garden
Road. The proposed drainage areas discharge to the storm drain system located on Town Garden Ct.
The proposed project plans very minor alterations to existing site drainage courses. These alterations
are not significant in terms of potential hydrologic impacts offsite, and are present in order to properly
treat and drain the site.
A detailed description of the drainage patterns and flows are discussed in the report titled "Hydrology
Report for Bressi Ranch Medical Plaza" prepared by Fuscoe Engineering.
BRESSI RANCH MEDICAL PLAZA 11 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
Project Site Drainage and Runoff Characteristics
{ 0 Impervious Area •C-Factor
100% 1.00
8O°/ 0
0.80 w : 60% 0.65
040 3 40%
a) o
20%
II
.
,.' I-,
0
0.35
0% I 0.20
Existing Proposed
Figure 1: Changes in site drainage and the coefficient of runoff as a result of the proposed
development.
2.2.1 PRE CONSTRUCTION CONDITIONS AND FLOW
Pre-project features for the existing site include a rough graded pad area sloping to the northeast. A
large desilting basin captures sheet flow, discharging it through the 36 CMP riser, or via the emergency
concrete spillway. The runoff is conveyed toward the existing 24 RCP on Town Garden Rd.
From the hydrology study, the 2, 10 and 100 year peak flow rates discharging from the site have been
calculated and are shown in the table below.
2.2.2 POST CONSTRUCTION CONDITIONS AND FLOW
Post-project conditions include the 2 story medical condominium center, parking lot, water quality
features, landscaping, and associated utilities and hardscape. The proposed site consists of 1 distinct
drainage area with 6 sub drainage areas.
Site development will generally maintain existing drainage patterns. The parking lot will be graded to
sheet flow to the east and drainage will be collected in a private storm drain system, tying in with the
24" existing storm drain at the northeast corner of the site. Biofiltration areas will be used for
conveyance and water quality treatment onsite. The proposed building will convey roof runoff to the
BRESSI RANCH MEDICAL PLAZA 12 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
southern side of the building where it will flow to the water quality treatment areas. The parking lot will
contain two parking landscape islands, both of which are envisioned to be depressed landscaping
areas for water quality purposes with 0" curbs. Both landscaping islands were designed to be
biofiltration swales.
PROPOSED DRAINAGE FLOWS
I DRAINAGE RAINAGE
AREA AREA Q2 (CFS) Q10 (CFS) Q100 (CFS)
(ACRE)
1 0.28 0.3 0.4 0.6
2 j 0.72 1.9 2.7 4.0
3 0.32 0.9 j 1.3 2.0
4 0.32 0.83 1.2 1.8
5 0.27 0.5 0.7 1.0
6 0.04 0.1 0.1 0.1
OVERALL FLOWS COMPARISO
DRAINAGE I
AREA Q2 (CFS) Q10 (CFS) Q100 (CFS)
(ACRE)
Existing
Site 1.95 1.5 2.1 3.2
Proposed
Without 1.95 4.0 5.7 8.6
Biofiltration
Proposed
With 1.95 2.5 4.3 7.8
Biofiltration
As a result of development, peak flows for the proposed site drainage areas will increase due to
increased amounts of impervious surfaces. Site design and treatment control BMPs described in Section
4.1 increase times of concentration, and function to detain, slow down, and treat flows from low to
moderate intensity storm events. Flows through the basins are noted as Post Reduction, in the table
above. Calculation details are included in Appendix 5. These calculations show the site flow and
storm volumes routed through the basins, resulting in an increased time of concentration, as compared
to the proposed pre reduction condition.
The downstream hydrologic impacts have been previously addressed in the master drainage plan for
the Bressi Ranch area. This master plan outlines the flows stemming from the anticipation of
development of the greater project area, and the mitigation measures necessary. Any regional
BRESSI RANCH MEDICAL PLAZA 13 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
detention facilities were designed through the master planning process, and are therefore not needed
on the proposed Bressi Ranch Medical Plaza project site.
Per Model SUSMP, interim hydromodification criteria only applies to projects which disturb an area of
50 acres or greater, therefore the proposed project does not apply. As stated in the Drainage Study for
Bressi Lot 1, the previously allowable Qi 00 value for the project site, referenced in the backbone
drainage studies was 8.8 cfs. The proposed project has a Q100 of 8.6 cfs. The proposed 2 and 10
year flow increase does not conflict with any requirements set forth in the master drainage plan or
previously issued permitted conditions. Calculations are included in Appendix 5.
The Bressi Ranch Medical Plaza project proposes to minimize the increase in peak flows through low
impact site design, utilizing disconnected connected impervious surfaces, and high level filtration based
water quality treatment. In addition, landscaping and curb cuts will be used onsite in order to minimize
the amount curb and gutter flow conditions onsite. These and other techniques outlined in the 2007
San Diego County Low Impact Development (LID) Handbook will be used onsite to minimize impacts
concerning the hydrologic flow regime.
For more detailed information concerning proposed hydrology, reference the report titled 'Hydrology
Report for Bressi Ranch Medical Plaza" prepared by Fuscoe Engineering.
2.3 POTENTIAL POLLUTANTS
There is no sampling data available for the existing site condition. The following constituents are
commonly found on similar developments and could affect water quality:
Sediment discharge due to construction activities and post-construction areas left bare
Nutrients from fertilizers used in landscaping
Organic compounds found in pesticides, solvents, and hydrocarbons
Trash and debris deposited in drain inlets
Hydrocarbons such as oil and grease from paved areas
ANTICIPATED AND POTENTIAL POLLUTANTS
Z Z
Z
oö
LU Z
ZZ u J
- UJ LU
> - <
Z'.'
< T Z z <
(I, Z I Ou ,- a O Oi co > a-
Detached Residential x Development
x x x x x
Attached Residential x x x pm p) pIll X Development
Commercial P P p12 X 05) p)31 p15) Develo1 ment
Heavy Industrial pIll pI p21 X p x p(3) pS) Development
BRESSI RANCH MEDICAL PLAZA 14 WATER QUALITY ENVIRONMENT
ANTICIPATED AND POTENTIAL
I
POLLUTANTS
I
U, I
U, z zej
ZZ
U, LU
LU
z 01", < U5 fu
z i 0u a 09U, 00 co > IL ,
Automotive Repair x X1451 Shops =
Restaurants X X X X
Steep Hillside
Development x x x x x.
Parking Lots pIll1 pi X x pill X
Retail Gasoline
Outlets x x x x x
Streets Highways and x' pIll X x , P(51 x Fre.ewcys., . .' '
Notes: -
* X = Anticipated -
P= Potential
A potential pollutant if landscaping exits on-site. -
A potential pollutant if the project includes uncovered parking areas . ., .
A potential pollutant if land use involves food or animal waste products.
Including petroleum hydrocarbons . . . Including solvents
,- • 1•
a.
Receiving waters have 303(d) beneficial use impairments consisting of DDE, Phosphorus, and Sediment
Toxicity. . . . .
According to the table provided above, which was lifted from the City of Carlsbad SUSMP/ Storm Water
Standards Manual, the designations of Parking Lots, and Streets, Highways and Freeways have
antiéipated or potential pollutants for sediment, nutrients, heavy metals, organic cmpounds, trash and
debris, oxygen demanding substances, oil and grease, and pesticides.
-
Therefore, the following
pollutants are designated as anticipated or potential for the proposed site, as well as have 303(d)
impairments downstream are considered primary pollutants of concern.
PRIMARY POLLUTANTS OF SPECIFIC 303(D) IMPAIRMENT CONCERN
I • -'
PESTICIDES - : . . DDE • • '•
NUTRIENTS
. PHOSPHOJRS
SEDIMENT SEDIMENT TOXICITY
-- * Dichlorodiphenyldichloroethylene (DDE) is formed through the degradation of DDT, a common •
- pesticide used widely until its prohibition in 1972. The use of DDT is not anticipated onsite. Although.
remnants of DDT and DDE are possible almost anywhere in the United States the site is not considered
1 • • - .• - -I . -• • c - -• •: - • .- - • - -, • r
I • ..- *
BRESSI RANCH MEDICAL PLAZA 15 WATER QUALITY ENVIRONMENT',i
STORM WATER MANAGEMENT PLAN MAY 2008
to be a significant source. The development of the project site is not expected to exacerbate any
beneficial use impairments on downstream waters stemming from the presence of DDE.
2.4 SOIL CHARACTERISTICS
The site is currently comprised of an area which is currently in a mass graded pad condition. The site is
sloped from southwest to northeast, with a large existing desilting basin constructed during the rough
grade. A geotechnical investigation was conducted by Southern California Geotechnical in January
2006, describing the subsurface conditions concerning the proposed development.
The fill materials consist of compacted fill, sandstone, and claystone bedrock. The compacted fill
extends up to 12 ft in depth and in combination with the bedrock is of high strength, and of varying
expansion potential. The description of the fill material is one that consists of sands, clayey sands, and
sandy clays with moderate expansive potential. It is expected that overexcavation of approximately 3
feet be conducted on the building pad to ensure the load bearing surface is solid and stable to support
the foundation.
Groundwater was not encountered during geotechnical investigations, however the borings only were
conducted to a depth of 20' bgs. Infiltrating large amounts of surface water through landscaping or
water quality features without sub-drainage is not recommended due to low infiltration rates. According
to the San Diego County Hydrology Manual, the Hydrologic Soil Type is type 'D". (Note: Information
regarding soil conditions is also available in the Soil Survey, San Diego Area, California, US
Department of Agriculture, 1973.) Soil type "D" denotes soils which have substandard infiltration rates,
and are composed of a high percentage of clays.
BRESSI RANCH MEDICAL PLAZA 16 WATER QUALITY ENVIRONMENT
STORM WATER MANAGEMENT PLAN MAY 2008
3.0 CONSTRUCTION BMPs
3.1 CONSTRUCTION PHASE POTENTIAL POLLUTANTS
The main potential pollutants due to construction activity are sediment and construction material waste.
Sediment is possible from grading operations, erosion, and poor stockpile management. Construction
material waste results from improper handling and disposal of waste materials, such as demolished AC
pavement and concrete or empty cans of paint, and not having a designated concrete wash out area. These
wastes can pollute storm water if not handled and disposed of properly. Site activities and potential pollutants
that could potentially be discharged in storm water are summarized below:
Table A - Potential Construction Phase Pollutants
ACTIVITY POLLUTANT SOURCE
Grading Sediment Tracking by vehicles, displacement by wind and equipment
Paving Asphalt and Concrete Asphalt and concrete
Construction Oil and Grease Vehicles and equipment
Painting Paint Painting of buildings and pavement and curbs
3.2 CONSTRUCTION PHASE BMPS
During construction, Best Management Practices (BMPs) from the California Storm Water Quality Association
Stormwater Best Management Practice Handbook-Construction (2003) will be used. The project will disturb
approximately 1 .95 acres, and is therefore subject to the statewide NPDES program and a SWPPP is required.
The following construction BMPs will be used (the BMP detail is listed next to each BMP):
Water Conservation Practices (NS-1)
Dewatering Operation (NS-2)
Paving and Grading Operations (NS-3)
Illicit Connection/Illicit Discharge (NS-6)
Vehicle and Equipment Cleaning (NS-8)
Vehicle and Equipment Fueling (NS-9)
Vehicle and Equipment Maintenance (NS-1 0)
Silt Fence (SE-1)
Fiber Rolls (SE-5)
Gravel Bags (SE-6)
Street Sweeping and Vacuuming (SE-7)
Storm Drain Inlet Protection (SE-1 0)
Scheduling (EC-1)
Hydroseeding (EC-4)
Stabilized Construction Entrance/Exit (TR- 1)
Stabilized Construction Roadway (TR-2)
Entrance/Outlet Tire Wash (TR-3)
Wind Erosion Control (WE-1)
Material Delivery and Storage (WM-1)
BRESSI RANCH MEDICAL PLAZA 17 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
Material Use (WM-2)
Stockpile Management (WM-3)
Spill Prevention and Control (WM-4)
Solid Waste Management (WM-5)
Hazardous Management (WM-6)
Concrete Waste Management (WM-8)
Sanitary/Septic Waste Management (WM-9)
Many of the BMPs listed above are "good housekeeping" that shall be followed in the location of building and
activity areas (e.g. fueling islands, waste container area, wash racks, material storage areas, etc.). The
construction staging area shall be determined by the contractor prior to the start of construction and noted in
the SWPPP. It shall be noted that the SWPPP is a living document and the contractor shall amend the plan as
required during construction.
The potential pollutants listed in section 3.1 will be controlled through the use of the BMPs listed on the
previous page.
Construction materials to be stored and handled at the site include but are not limited to asphalt, concrete,
paint, wood and metal. The typical quantities of these materials and their storage location are not known at
this time. Prior to construction the contractor shall show the designated location for material delivery and
storage on the plan and give a complete list of construction materials and typical quantities that will be stored
and handled on the project site. In addition, on the plan the contractor shall show locations where materials
will be directly exposed to storm water. As stated on the previous page, material delivery and storage and
material use will be conducted in accordance with guidelines set forth in BMP WM-1 and WM-2, respectively.
BRESSI RANCH MEDICAL PLAZA 18 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
4.0 POST CONSTRUCTION BMPs
To address water quality for the project, BMPs will be implemented concerning site planning, activities,
and structural treatment. City of Carlsbad Storm Water Standards Manual guidelines are utilized in the
selection of post construction BMPs. In addition, any features or activities included in the project that
are applicable for the inclusion of CASQA BMPs are included as well. BMP design and education
sheets are included in Appendix 3.
4.1 POST CONSTRUCTION BMPs
4.1.1 SITE DESIGN BMPs
The project is designed to include site design BMPs which reduce runoff, prevent stormwater pollution
associated with the project, and conserve natural areas onsite.
DESIGN CONSIDERED: YES NO DESCRIPTION
I I
' The project site will include a significant
MINIMIZE IMPERVIOUS amount of landscaping. The project site is
FOOTPRINT landscape small in size and includes planters
as well as surface landscaping and water
quality BMP areas.
Hillsides bordering the project site will remain
CONSERVE NATURAL in a vegetated condition. The existing project
AREAS/PROVIDE BUFFER site consists of rough graded pads, therefore
ZONES no natural areas exist onsite. There are no
watercourses bordering the project site.
Runoff from much of the project site will flow
through modified sand filter areas prior to
discharging to storm drain. The use of these
area as well as significant amounts of
MINIMIZE DIRECTLY landscaping allows for a large portion of site
CONNECTED IMPERVIOUS Z LJ runoff to have biological contact and
AREAS (DCIAS) infiltration, rather than directconnection to the
storm drain. The result is increased water
quality, decreased peak flow runoff and
volume, and increased times of concentration
onsite.
The site is currently in a rough graded pad
condition. Site landscaping includes large
numbers of trees and shrubs which are either
MAXIMIZE CANOPY native, drought tolerant, or both. Canopy
INTERCEPTION AND 0 El interception by trees and shrubs will occur
WATER CONSERVATION reducing the amount of runoff conveyed by
storm drain offsite. These tress and shrubs are
predominately located in the northern and
western portions of the project site.
BRESS! RANCH MEDICAL PLAZA 19 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
Slopes located to the south of the project site
I will be undisturbed by the proposed project.
PROTECT SLOPES AND Onsife 2:1 slopes located north and west of
CHANNELS 0 I the proposed office building will be vegetated
and stabilized during and after construction.
Runoff will be routed away from the top of
steer) slooes.
LID SITE DESIGN BMPS
Incorporating Low Impact Development (LID) design strategies for priority development projects is
required per R9-2007-0001, the Municipal Storm Water Permit issued to the County of San Diego and
the incorporated cities and districts within. The Bressi Ranch Medical Plaza project proposes to drain
impervioussurfaces to pervious areas for storm water treatment.
Only high level filtration style BMPs are chosen for the project site, as noted in the table located in
Section 4.1.3 obtained from the City of Carlsbad SUSMP/ Storm Water Best Management Practices
Manual. These filtration BMPs have a higher treatment effectiveness rating, and lead to positive effects
concerning storm water quality stemming from the project site. Features such as curb cuts are provided
as well to introduce site runoff directly into BMP areas, disconnecting the gutter flow in the parking lot
area. Building downspouts are disconnected as well, feeding into surface water quality treatment areas.
4.1.2 SOURCE CONTROL BMPs
"Source control BMP (both structural and non-structural)" means land use or site planning practices, or
structures that aim to prevent urban runoff pollution by reducing the potential for contamination at the
source of pollution. Source Control BMPs minimize the contact between pollutants and urban runoff.
SOURCE CONTROL BMP DESCRIPTION
Any hazardous material storage associated with the
DESIGN OUTDOOR MATERIAL building or greater project site will be stored inside,
STORAGE AREAS TO REDUCE protected from precipitation as well as run-on from
POLLUTION INTRODUCTION adjacent areas. Under no circumstances shall
materials with the potential for storm water
contamination be stored outside.
The trash storage area located in the eastern portion of
DESIGN TRASH STORAGE the project site shall be on impervious ground; as well
AREAS TO REDUCE as be walled and covered to prevent contact from
POLLUTION INTRODUCTION precipitation and run-on. Any spills or leaks of trash
will be contained within the trash enclosure.
BRESSI RANCH MEDICAL PLAZA 20 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
SOURCE CONTROL BMP DESCRIPTION
The need for pesticide use in the project design will b
eliminated and/or reduced by:
Planting pest-resistant or well-adapted plant varietals
such as native plants
Discouraging pests by designing the site and landscape
to employ pollution prevention as a first-line of defense.
Distributing Integrated Pest Management (IPM)
EMPLOY INTEGRATED PEST educational materials to maintenance staff. At a minimum,
MANAGEMENT PRINCIPES educational materials will address the following topics:
L Keeping pests out of buildings and landscaping
using barriers, screens and caulking
Physical pest elimination techniques, such as
weeding, squashing, trapping, washing or pruning out
pests
Relying on natural enemies to eat pests
Proper use of pesticides as a last line of defense.
Rain shutoff devices will be installed to prevent
USE EFFICIENT IRRIGATION irrigation during and after precipitation events. In
SYSTEMS AND LANDSCAPE addition, flow reducers or shutoff valves will be installed
DESIGN to control water loss. The overall irrigation system will
be designed taking into account water needs of each
individual area as well as water conservation strategies.
PROVIDE STORM WATER Curb stenciling shall say No Dumping- I Live
CONVEYANCE SYSTEM Downstream or equivalent massage as desired by the
STENCILING AND SIGNAGE City of Carlsbad.
SURFACE PARKING AREAS Surface parking will be routed through vegetated water
quality treatment areas.
4.1.3 TREATMENT CONTROL BMPs
Runoff from the proposed site will flow from impervious and semi-pervious surfaces, picking up
pollutants and other associated debris from the proposed Bressi Ranch Medical Plaza Site. Treatment
of these anticipated pollutants will come from the BMPs listed in this Section. The BMPs were selected
based on new treatment matrices found in the November 2007 San Diego County SUSMP update. The
City of Carlsbad directed Fuscoe Engineering to use these new documents in preparation of this SWMP.
The following shaded areas represent the primary pollutants of concern, and note the nature of those
pollutants as related to treatment removal. Treatment BMPs were chosen based on this as well as other
factors regarding applicability and functionality.
BRESS! RANCH MEDICAL PLAZA 21 SUMM,ARYAND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
SITE POLLUTANTS OF CONCERN REMOVAL CHARACTERISTICS
COURSE POLLUTANTS THAT 'POLLUTANTS THAT TEND TO
SEDIMENT AND TEND BE DISSOLVED FOLLOWING
TRASH WITH FINE PARTICLES TREATMENT DURING TREATMENT
NUTRIEJTS X X
HEAVY METALS X
ORGANIC COMPOUNDS X
TRASH AND DEBRIS X
OXYGEN DEMANDING
SUBSTANCES X
BACTERIA x
OIL &GREASE X
PESTICIDES x
Certain factors such as site layout, soil feasibility, and treatment capability are taken in to account when
selecting treatment control BMPs. Possible BMP solutions and descriptions concerning feasibility onsite
are described in the table below. The goal in selecting treatment control BMPs is to find the best
solution as to promote water quality treatment, realize project objectives, remain cost efficient, and
utilize low impact design (LID) practices.
TREATMENT CONTROL BMP: YES N/A DESCRIPTION
Modified Sand Filter Trenches are
classified as "bioretention" for this
BIORETENTION FACILITIES project. The water quality volume will
filter through the treatment area prior
to discharge to the perforated sub-
______________________________ drainage system.
Adequate room for a dry basin or
SETTLING BASINS AND wetland is not available onsite.
WETLANDS Alternative modified sand filter trench
areas used for treatment.
Not utilized for this project. Soil
infiltration rates in the area are
INFILTRATION FACILITIES OR substandard for infiltration. In addition
PRACTICES El 0 the geotechnical engineer discourages
the infiltration of water due to clay
content in soils and substandard
infiltration rates.
Although similar, the modified sand
MEDIA FILTERS filter trenches are classified as
"bioretention" in the criterion for this
project.
BRESSI RANCH MEDICAL PLAZA 22 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
TREATMENT CONTROL BMP:
•
HIGH RATE BIOFILTERS
YES N/A DESCRIPTION
I Another high quality BMP was used on
this project.
HIGH RATE MEDIA FILTERS A more effective BMP is used for this
• project.
An existing offsite PSWC 40 40 CDS
Unit is located downstream of the
proposed project site along Town
DRAINAGE INSERTS - D Garden Road. r The CDS Unit will assist
- in the "Treatment Train" approach-of,,
storm water pollutant removal. The
CDS unit is successful in removing
sediments, trash, and oil/grease.
As discussed above, "Bioretention" style treatment control BMPs will be implemented to address water
quality, based on the Primary Pollutants of Concern/303(d) list for the project site. •-
TREATMENT CONTROL BMP SELECTION MATRIX
I
LLJ
LLA
00 h hr CL LLJ
Qu Ia t :c Ova LU C,' I
COURSE . .. . SEDIMENT AND AIGhi HIGH HIGH HIGH HIGH HIGH HIGH HIGH
TRASH
POLLUTANTS ' ". - •' -
THAT TEND TO
ASSOCIATE WITH
PARTICLES HIFINE GH HIGH HIGH HIGH HIGH MEDIUM MEDIUM LOW
DURING
TREATMENT
POLLUTANTS
THAT TEND TO
BE DISSOLVED MEDIUM LOW MEDIUM HIGH LOW LOW LOW LOW
FOLLOWING
TREATMENT
The Modified Sand Filter Trenches, which are classified as "Bioretention" style BMPs, have a high or
medium removal rating for the three applicable categories concerning the Primary Pollutants of •
Concern onsite. The offsite CDS Unit has high removal for course sediments and trashy and functions
as downstream back up to the onsite treatment BMPs. -
-
- •- . ,•. • '-4 . •
- BRESSI RANCH MEDICAL- PLAZA 23 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
CONTROL 1: BIORETENTION- MODIFIED SAND FILTER TRENCHES
V B,, SUMMARY
I I I
24 hr Required BMP Storage I
Draw Drainage C 85% Treatment BMP Volume Down Area Value ATOTAL (ac) Storm Volume Footprint Surface+ Time (ft)
(in) (ft') Sub-Surface (days) (ft3)
DRAINAGE 0.85 0.72 0.70 1555
J
576 742* 0.70 AREA 2:
DRAINAGE 0.85
J
0.32 0.70 691 672 865 0.40 AREA 3:
DRAINAGE 0.85 1 0.32 0.70 691 621 1,539 0.39 AREA 4:
TOTAL
-
1.36 - 2,918 1,920 3,146 -
Notes:
Calculations are based on Carlsbad Storm Water Standards Manual, SUSMP
See Appendix 4 For Calculation Details
Excess will sheet flow to Sand Filter in Drainage Areas 3 and 4.
Per the City of Carlsbad SUSMP/ Storm Water Standards Manual, volume based treatment control
BMPs on the Bressi Ranch Medical Building site have been designed to treat the volume of runoff
produced by the 85th percentile storm event. This event is shown on the San Diego County 85th
percentile isopluviol map dated 8/7/2003, and is 0.70 for the project location. Modified Sand Filter
Trench areas are the primary treatment control BMP for the parking areas and parking structure.
Modified Sand Filter Trench areas are designed per standard TC-40 in the California Storm Water BMP
Handbook. (4)
The modified sand filter trenches will act as volume-based BMPs and are therefore sized to treat an
amount of runoff calculated by method 1 in the Carlsbad SUSMP/Storm Water Standards Manual.
Water quality volume and BMP sizing calculation details are shown in Appendix 4.
This will allow the first flush storm water runoff to accumulate in the modified sand filter trench, prior to
discharge offsite. The residence time in the basin will be less than 48 hours, for vector control
purposes, allowing time for the settling and filtration of strormwater runoff into the filter medium. This
meets the capacity requirements shown below based on calculations outlined in CASQA TC-40 using
Darcys Law to size filtration areas and calculate drawdown time. The sizing calculation relates the
velocity of fluids to the hydraulic head and the coefficient of permeability of a medium. The resulting
equation is Af= WQV d/[k t (h+d)]. See Appendix 4 for explanation of the calculations in further detail.
The modified sand filter trenches are limited in size due to the constraints and grades of the proposed
project site. However, the design of the trenches ensures that the 85th percentile storm, which is 0.70
inches at the proposed project site, will be treated over the 24 hour time period.
As shown in the sizing calculations located in Appendix 4, an infiltration rate of 2.14 in/day is used.
This is an extremely conservative rate, based on CASQA TC-40. In reality, permeability rates up to and
exceeding 10-15 feet/day are likely considering the uncompacted design of the filter. As proposed, the
filters can store well over the water quality volume, due to both above ground and subsurface storage in
the filter medium. The design storm however is a 24 hour event, in which the filters will function
BRESSI RANCH MEDICAL PLAZA 24 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
throughout. As the storm progresses, storm water will filter down through the layers, reaching the storm
drain through the perforated sub-drainage system. Over the 24 hour period, the drawdown of the filter
trenches will consistently allow storm water to be treated, ensuring that the water quality volume is
stored throughout. Drawdown of a filter can be determined by rearranging the Darcys law equation,
obtained from CASQA TC-40.
(Basin 2)
t= (WQV x d) / (k x Af x (h+d))
= (1555 x 3)! (2.14 x 576 x (3 +0.65))
= 1 .0 days
The drawdown of the filter trenches can be estimated at 1 .0 days maximum, if completely full.
Therefore, during the 24 hour period the filter trenches will be able to simultaneously treat and store the
appropriate water quality volume. The filter trenches in Basins 2 and 3 are not equipped with overflow
risers, therefore overflow storm water will sheet flow to the filter trench in Basin 4, which is oversized for
its respective drainage area.
Side slopes will be vegetated at a slope ratio of 2:1. The primary removal mechanism is the filtration of
particles and pollutants through the filter medium to the perforated sub-drain. The basin bottom will be
vegetated with plants which aid in the filtration of pollutants and can survive in this kind of environment.
The areas are designed so that overflow is conveyed by sheet flow to the east into the designated water
quality areas.
The filter consists of planting soil above hemic or fibric peat, sand, and gravel medium, designed for
the filtration of pollutants from the first flush strormwater runoff. The top layer will consist of 3" of
planting soil, above 8". inches of peat, designed to adsorb pollutants, (particularly nutrients) prior to
further downward filtration. The 16" sand layers further treat the storm water through sorption and
filtration processes. The sub-drain is located in the bottom 8" gravel layer which is wrapped in Mirafi
1 40N (or similar) geotextile fabric. Once the storm water runoff has filtered through the filter medium,
it enters the perforated pipe and is discharged as treated storm water to storm drain leaving the site.
See Appendix 4 for details.
CONTROL 2: PREVIOUSLY SIZED OFFSITE CDS UNIT
An existing CDS Unit located downstream of the project site will act as a flow-based BMP and sized to
treat an amount of runoff calculated by the following equation (given in the SUSMP):
QWQ = C IWQX A
Where:
QWQ Flow rate for water quality purposes (cfs)
BRESSI RANCH MEDICAL PLAZA 25 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
C = Weighted runoff coefficient (greater developed area) = 0.95
'wQ = Rainfall intensity for the treatment design storm (in /hr) = 0.2 in /hr
A = Area tributary to the treatment control device (AC) = 23.1 ac
The CDS unit was installed underground in the storm drain system to remove pollutants typically
associated with commercial development, including debris, trash, oil and grease, sediment and parking
lot particulates from storm water. Details concerning these treatment BMPs are outlined in Appendix 4.
The capacity for CDS unit PWSC 4040 is 6.0 cfs. This meets the capacity requirements based on the
contributing watershed area, as shown above.
The CDS Units proposed for the project site are designed to allow for settling of sediment, as well as
removal of oil and grease from the oil baffle located in the unit. The unit is located on Town Garden
Road, and will be maintained by the master plan developer.
BRESSI RANCH MEDICAL PLAZA 26 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
5.0 MAINTENANCE
The operation and maintenance requirements for each type of BMP are contained in the following
sections. If a transfer of responsibility occurs, the property management association will notify the city
using the form included in Appendix 2 as a notice of transfer. If a contractor conducts maintenance
onsite the property management association is still responsible for the correct implementation of this
document. It is up to the property management association to instruct the contractor to maintain the
property in the correct fashion.
To Be Formed Property Management Association:
Interim Contact -Bressi Ranch Medical Plaza LLC
1 280 Bison Ave # 139-609
Newport Beach, CA 92660
Fax: 714-292-9007
MAINTENANCE MECHANISM
Project Proponent Agreement to Maintain Storm Water BMPs
Details are provided in this section. Maintenance Agreement is provided in Appendix 6.
5.1 POST CONSTRUCTION BMPs
Post-construction BMPs are to be maintained in perpetuity. Maintenance requirements for source
control BMPs as well as treatment control basin and swale are shown below. It shall be noted that
preventative maintenance such as removal of trash and debris from the site will help ensure proper
function of the BMPs.
SITE lIrkiU
FREQUENCY
I The site is to be maintained and monitored
MINIMIZE IMPERVIOUS Property Management to ensure impervious areas are not
FOOTPRINT Association expanded or developed at the expense of
pervious areas.
CONSERVE NATURAL Property Management Periodic monitoring of buffer areas along
AREAS/PROVIDE BUFFER Association southeast perimeter to ensure trash and
ZONES debris does not accumulate.
MINIMIZE DIRECTLY
CONNECTED IMPERVIOUS Property Management Periodic monitoring of landscaped areas to
AREAS (DCIAS) Association ensure proper drainage and upkeep.
MAXIMIZE CANOPY
INTERCEPTION AND WATER Property Management Periodic monitoring of trees to ensure
CONSERVATION Association proper health and upkeep.
BRESS! RANCH MEDICAL PLAZA 27 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
IPeriodic monitoring to ensure slope
PROTECT SLOPES AND Property Management ( stability. Any erosion or nIPs should be
CHANNELS Association noted and slope stabilization techniques
employed using lute netting, EC blankets,
or re-vegetation.
SOURCE CONTROL BMP RESPONSIBLE PARTY MINIMUM MAINTENANCE FREQUENCY
DESIGN OUTDOOR MATERIAL Property Management Loading areas should be inspected and STORAGE AREAS TO REDUCE
Association cleaned on a monthly basis. POLLUTION INTRODUCTION
DESIGN TRASH STORAGE Property Management Periodic normal maintenance to ensure trash
AREAS TO REDUCE Association is contained and the area is not a potential
POLLUTION INTRODUCTION runoff pollution problem area.
In conjunction with maintenance activities,
verify that landscape design continues to
USE EFFICIENT IRRIGATION function properly by adjusting properly to
SYSTEMS AND LANDSCAPE Property Management eliminate overspray to hardscape areas, and
DESIGN Association to verify that irrigation timing and cycle
lengths are adjusted in accordance with
water demands, given time of year, weather,
and day or night time temperatures.
Storm drain stencils shall be inspected for
PROVIDE STORM WATER Property Management legibility, at minimum, once prior to the
CONVEYANCE SYSTEM Association storm season, no later than October 1 each
STENCLING AND SIGNAGE year. Those determined to be illegible will
be re-stenciled as soon as possible.
In conjunction with maintenance activities,
EMPLOY INTEGRATED PEST Property Management verify that IPM principles are followed.
MANAGEMENT PRINCIPES Association Includes education of new staff and
residents.
Street sweeping within the internal roads and
parking lot areas shall be conducted at a
minimum frequency of once per year prior to
SURFACE PARKING AREAS Property Management the rainy season.
Association
Periodic normal maintenance to ensure
parking area is absent of trash and any other
potential contaminants.
Maintained monthly in conjunction with
regular landscaping activities, including
BIORETENTION- MODIFIED Property Management removal of trash/ debris/sediment, weed
SAND FILTER TRENCH Association control, and watering during drought
conditions. Damaged or dead plant areas
shall be repaired upon detection. Height of
BRESSI RANCH MEDICAL PLAZA 28 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
vegetation on basin floor to be maintained to
12 inches or less. Monitoring for clogging is
crucial for the success of sand filter areas.
See below for details.
5.2.1 BIORETENTION- MODIFIED SAND FILTER TRENCHES
In the modified sand filter trenches, routine maintenance activity consists primarily of debris removal
and vegetation management. Sediment accumulation is possible, and the area needs to be inspected
for possible clogging. If the area is not draining in 72 hours, clogging has occurred and the removal of
the top layer of the filter is required. Clogging of the top layer of the filter is possible and major
maintenance is expected every 2-5 years. The yearly removal sediment/silt material which has
accumulated on the surface is recommended in order to prevent the need for molar maintenance of the
filter once it has become totally clogged.
Inspect per CASQA TC-32. Inspections should occur once a month during the rainy season after a
runoff producing event to ensure the area is functioning properly. Plants should be maintained and
kept healthy. If area is not draining within 72 hours, inspect inflow point for excessive sedimentation
and conserved removal of surface material. Excess sediment shall be removed and disposed of
properly. The inlets/outlets shall be inspected frequently for clogging and cleaned out as necessary.
Vegetation shall be trimmed at the beginning and end of the wet season and inspected monthly to
prevent establishment of woody vegetation. -
Monitoring will occur on a monthly basis during the first year and quarterly thereafter. Quantitative
data will be collected annually to evaluate frequency of maintenance activities and adjustments to
scheduling will be made accordingly
5.3 FISCAL RESOURCES
Following the completion of the project, the property management association will be responsible for all
areas within private property as follows: properly disposing of waste material from their assumed areas
within the project site, maintaining landscaping throughout those areas in a manner that will prevent
soil erasion and minimize sediment transport, maintaining drainage facilities in a clean manner and in
good repair, and properly maintaining all post-construction BMPs (both structural and non-structural)
that exist within the private property of the project.
It should be noted that maintenance for any of the above mentioned post-construction BMPs may be
performed through third-party agreements; however, the ultimate responsibility of each facility rests on
the entity denoted above. BMP maintenance casts are listed below.
BRESS! RANCH MEDICAL PLAZA 29 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
BMP OPTION
ESTIMATED
CAPITAL APPROXIMATE ANNUAL MAINTENANCE
COSTS COSTS
MODIFIED SAND FILTER TRENCH $5-20/SF =
$17 K- $67 K $0.50 SF= $1,665- Similar to landscaping.
TRASH STORAGE AREA $1, 000-
$3,000 Included in General Site Maintenance
CATCH BASIN STENCILING $10 per inlet $0 (Re-stencil at $10/inlet when needed)
TOTAL $18,000 TO
$70,000 $1,500 -$2,000 /YR
eased on information obtained trom LAS(A I3MF lactsheets, I L-'2, and Laltrans Pilot BMP Study
BMP Anticipated Operation and Maintenance Costs.
The developer shall incur the costs for the BMP installation. The responsible party for long term
maintenance and funding is the Property Management Association.
BRESSI RANCH MEDICAL PLAZA 30 SUMMARY AND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
6.0 SUMMARY AND CONCLUSIONS
The use of source control and site design BMPs in practice through the day to day function of the
project will result in a decreased potential for stormwater pollution as opposed to the existing condition
Treatment control BMPs will function around the clock, providing removal of pollutants from storm
water runoff.
Maintenance will be conducted by the property management association, who will maintain the Site
Design, Source Control, and Treatment Control BMPs throughout the lifetime of the project. In the
event of sale of the site, the new owner will be required to maintain BMPs, ensuring proper function in
perpetuity.
ANNUAL CERTIFICATION OF BMP MAINTENANCE
The maintenance entity shall verify BMP implementation and ongoing maintenance through inspection,
self-certification, survey, or other equally effective measure. The certification shall verify that, at a
minimum, the inspection and maintenance of all structural BMPs including inspection and performance
of any required maintenance in the late summer / early fall, prior to the start of the rainy season. The
enforcement and verification of this task is conducted by The City of Carlsbad Storm Water NPDES
Coordinator, who can be reached at (760) 602-2799.
The city will only verify that the appropriate documentation of maintenance exists. It is the property
management association's sole responsibility to conduct maintenance and provide work orders/receipts
etc, upon request.
LONG-TERM FUNDING FOR BMP MAINTENANCE
Long-term funding for BMP maintenance shall be funded by the property management association.
ACCESS EASEMENT FOR CITY INSPECTION
The property management association assumes responsibility for operation and maintenance of
structural BMPs, however if needed the City of Carlsbad shall be granted able access for inspection
through a formal agreement.
BRESSI RANCH MEDICAL PLAZA 31 SUMMARYAND CONCLUSIONS
STORM WATER MANAGEMENT PLAN MAY 2008
7.0 APPENDICES
Appendix 1 Runoff Coefficient References
Appendix 2 Notice of Transfer of Responsibility
Appendix 3 BMP Educational Fact Sheets
Appendix 4 Treatment Control BMP Specifications
Appendix 5 Proposed Hydrology
Appendix 6 BMP Maintenance
BRESSI RANCH MEDICAL PLAZA 32 APPENDICIES
Certification
This Storm Water Management Plan has been prepared under the direction of the following Registered Civil
Engineer. The registered Civil Engineer attests to the technical information contained herein and the
engineering data upon which recommendations, conclusions, and decisions are based.
Paul Haaland Date
RCE #63656
Expires 09/30/08
OFESSi0
No. RCE 63656 J * EXP. 9-30-08
CiVI
*
J€OF C
. ___________
San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 4 of 26
The storm frequency of peak discharges is the same as that of I for the given T.
The fraction of rainfall that becomes runoff (or the runoff coefficient, C) is independent
of I or precipitation zone number (PZN) condition (PZN Condition is discussed in
Section 4.1.2.4).
The peak rate of runoff is the only information produced by using the RM.
3.1.2 Runoff Coefficient
Table 3-1 lists the estimated runoff coefficients for urban areas. The concepts related to the
runoff coefficient were evaluated in a report entitled Evaluation, Rational Method "C"
Values (Hill, 2002) that was reviewed by the Hydrology Manual Committee. The Report is
available at San Diego County Department of Public Works, Flood Control Section and on
the San Diego County Department of Public Works web page.
The runoff coefficients are based on land use and soil type. Soil type can be determined from
the soil type map provided in Appendix A. An appropriate runoff coefficient (C) for each
type of land use in the subarea should be selected from this table and multiplied by the
percentage of the total area (A) included in that class. The sum of the products for all land
uses is the weighted runoff coefficient (E[CA]). Good engineering judgment should be used
when applying the values presented in Table 3-1, as adjustments to these values may be
appropriate based on site-specific characteristics. In any event, the impervious percentage
(% Impervious) as given in the table, for any area, shall govern the selected value for C. The
runoff coefficient can also be calculated for an area based on soil type and impervious
percentage using the following formula:
34
San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 5 of 26
C = 0.90 x (% Impervious) + C,, x (1 -. % Impervious)
Where: C,, = Pervious Coefficient Runoff Value for the soil type (shown in
Table 3-1 as Undisturbed Natural Terrain/Permanent Open Space,
0% Impervious). Soil type can be determined from the soil type map
provided in Appendix A.
The values in Table 3-I are typical for most urban areas. However, if the basin contains rural
or agricultural land use, parks, golf courses, or other types of nonurban land use that are
expected to be permanent, the appropriate value should be selected based upon the soil and
cover and approved by the local agency.
3-5
San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26
Table 3-I
RUNOFF COEFFICIENTS FOR URBAN AREAS
Runoff Coefficient "C"
Soil Type
NRCS Elements County Elements %IMPER. A B C D
Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 0.30 0.35
Low Density Residential (LDR) Residential, 1.0 DU/A or less 10 0.27 0.32 0.36 0.41
Low Density Residential (LDR.) Residential, 2.0 DU/A or less 20 0.34 0.38 0.42 0.46
Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 0.45 0.49
Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 0.48 0.52
Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 0.54 0.57
Medium Density Residential (MDR) Residential, 10.9 .DU/A or less 45 0.52 0.54 0.57 0.60 Medium Density Residential (MDR) Residential, 14.5 DU/A or less 50 0.55 0.58 0.60 0.63 High Density Residential (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 0.69 0.71
High Density Residential (HDR) Residential, 43.0 DU/A or less 80 0.76 0.77 0.78 0.79 Commercial/Industrial (N. Corn) Neighborhood Commercial 80 0.76 0.77 0.78 0.79 CommerciaVlndustrial (0. Corn) General Commercial 85 0.80 0.80 0.81 0.82 Commercial/Industrial (OP. Corn) Office Professional/Commercial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (Limited 1.) Limited Industrial 90 0.83 0.84 0.84 0.85 Commercial/Industrial (General I.) General Industrial 95 0.87 0.87 0.87 0.87
'The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff
coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area
is located in Cleveland National Forest).
DU/A = dwelling units per acre
NRCS = National Resources Conservation Service
3-6
c
NOTICE OF TRANSFER OF RESPONSIBILITY
STORM WATER MANAGEMENT PLAN
Bressi Ranch Medical Plaza
Submission of this Notice Of Transfer of Responsibility constitutes notice to the City of Carlsbad
that responsibility for the Storm Water Management Plan ("SWMP") for the subject property
identified below, and implementation of that plan, is being transferred from the Previous Owner
(and his/her agent) of the site (or a portion thereof) to the New Owner, as further described
below.
Previous Owner! Previous Responsible Party Information
Company! Individual Name: Contact Person:
Street Address: Title:
City: State: ZIP: Phone:
Information about Site Transferred
Name of Project (if applicable):
Title of SWMP Applicable to site:
Street Address of Site (if applicable):
Planning Area (PA) and/
or Tract Number(s) for Site:
Lot Numbers (if Site isa portion of a tract):
Date SWMP Prepared (and revised if applicable):
New Owner! New Responsible Party Information
Company! Individual Name: Contact Person:
Street Address: Title:
City: State: ZIP: Phone:
Ownership Transfer Information
General Description of Site Transferred to General Description of Portion of Project!
New Owner: Parcel Subject to SWMP Retained by Owner
(if any):
Lot' Tract Numbers of Site Transferred to New Owner:
Remaining Lot! Tract Numbers Subject to SWMP Still Held by Owner (if any):
Date of Ownership Transfer:
Note: When the Previous Owner is transferring a Site that is a portion of a larger project/
parcel addressed by the SWMP, as opposed to the entire project/parcel addressed by the
SWMP, the General Description of the Site transferred and the remainder of the project'
parcel no transferred shall be set forth as maps attached to this notice. These maps shall
show those portions of a project' parcel addressed by the SWMP that are transferred to the
New Owner (the Transferred Site), those portions retained by the Previous Owner, and those
portions previously transferred by Previous Owner. Those portions retained by Previous
Owner shall be labeled as "Previously Transferred".
Purpose of Notice of Transfer
The purposes of this Notice of Transfer of Responsibility are: 1) to track transfer of
responsibility for implementation and amendment of the SWMP when property to which the
SWMP is transferred from the Previous Owner to the New Owner, and 2) to facilitate
notification to a transferee of property subject to a SWMP that such New Order is now the
Responsible Party of record for the SWMP for those portions of the site that it owns.
Certifications
Previous Owner
I certify under penalty of law that I am no longer the owner of the Transferred Site as
described in Section II above. I have provided the New Owner with a copy of the
SWMP applicable to the Transferred Site that the New Owner is acquiring from the
Previous Owner.
Printed Name of Previous Owner Title:
Representative:
Signature of Previous Owner Date:
Representative:
New Owner
I certify under penalty of law that I am the owner of the Transferred Site, as described
in Section II above, that I have been provided a copy of the SWMP, and that I have
informed myself and understand the New Owner's responsibilities related to the
SWMP, its implementation, and Best Management Practices associated with it. I
understand that by signing this notice, the New Owner is accepting all ongoing
responsibilities for implementation and amendment of the SWMP for the Transferred
Site, which the New Owner has acquired from the Previous Owner.
Printed Name of New Owner
Representative:
Title:
Signature: Date:
- - I - -- -.
I-
__l dTI1
rhe City of Carlsbad has developed an
nventory of all existing commercial and
ndustrial businesses and has prioritized
them according to the type of business,
Droximity to the nearest water body and
Dotential threat to water quality. Based on
this prioritization, the City will be conducting
;torm water compliance inspections of all
ndustrial and most commercial facilities
Nithin the City. These site inspections will
nclude a meeting with business
epresentatives, a walk-through of the
Facility, evaluation of current storm water
Dest management practices and
-ecommendations for additional measures
that may be required to comply with the new
iermit and nrdinance. In addition to the
ndustrial and commercial inspections, the
:ity is also performing construction site
nspections, conducting a comprehensive
;trom drain monitoring program to detect
pollutants, enforcing urban runoff
'equirements for new developments and
:onducting frequent cleaning of the storm
drain system.
The water that drains down a sink or toilet
flows to the sanitary sewer and is treated at
a wastewater treatment plant. The storm
drain, on the other hand, is designed to
carry rainwater away from streets, parking
lots and driveways to prevent flooding. This
water does not receive any treatment and
flows directly into our creeks, lagoons and
ocean.
"e, ProteC'°
. City of Carlsbad
1635 Faraday Avenue
7' Carlsbad CA 92008
Storm Water HOTline: 760-602-2799
stormwater@ci.carlsbad.ca.us
.) Printed on recycled paper
. ..
- -.4
CityofçarIsbad
Storm Water Protection Program
I Storm Water HOThne
760-602-2799
Sanitary Sewer vs. Storm Drain
What's the difference?
Pollution Prevention Is Up to US!
Did you know that storm drains are NOT
connected to sanitary sewer systems or
treatment plants? The primary purpose of
storm drains is to carry rainwater away from
developed areas to prevent flooding. As
rainfall flows over the ground, it picks up a
variety of pollutants which flow directly to our
creeks, lagoons and ocean.
Pollutants of concern include:
Sediments
Fertilizers
Metals
Detergents
Pesticides
Organic Compounds
Trash and Debris
Oil and Grease
Bacteria and Viruses
Pollution Prevention Is Up to US!
Best Management Practices (BMPs) are
procedures and practices you can implement
to prevent pollutants and other hazardous
materials from entering our storm drains.
Once potential and existing sources of
pollution have been identified, the next step is
to select proper BMPs to eliminate or reduce
storm water pollution. Program staff is
available to provide information and
assistance in developing BMPs for your
business. Each of us can do our part to keep
storm water clean. Using BMPs adds up to a
pollution solution!
Good Housekeeping
instead of using a hose or pres
washing system, try a dry clean
method! Use mops, brooms or
wire brushes to clean dumpste
sidewalks, buildings,
equipment, pavement,
driveways and other
impervious surfaces. Wash
water should be disposed to the sanitary sewer,
NEVER to the storm drain.
Minimize the use of cleaning solutions and
agents.
Keep site free of litter and debris. Place
trash cans and recycling receptacles around the
site to minimize litter.
Preventive Maintenance
Keep equipment and vehicles in good working
condition. Inspect frequently for leaks and
repair as needed.
Gutters, storm drains, catch basins and other
storm drainage features should be regularly
inspected and cleaned so that pollutants do not
accumulate.
Label storm drains to remind employees that
discharge to these drains flows directly to our
waterways.
Materials Storage and Handling
When possible, store materials indoors or under
covered areas not exposed to rain. If materials
can not be stored under cover, place materials
on pallets and cover with a tarp to avoid contact
with storm water run-on and run-off.
Store liquids, hazardous waste and other
chemicals in a designated area with secondary
containment. Keep outdoor storage areas in
good condition.
Waste Management
Sweep up around dumpsters and other areas
frequently to prevent trash from accumulating.
Place all trash inside dumpsters or containers
until it can be hauled away.
Dumpsters should always be kept closed to
prevent rainwater from entering. Never place
liquid waste, leaky garbage bags and hazardous
waste in a dumpster or trash bin.
Recycle cans, bottles, newspaper, office paper
and cardboard. Call 1-800-CLEANUP for more
information about recycling programs in your
area.
Vehicle Washing and Cleaning
Wash company vehicles at a commercial car
wash, whenever possible. If vehicles are washed
onsite, wash water must be contained and
disposed of to the sanitary sewer.
Spill Response
Use brooms and absorbents such as cat litter or
sawdust to clean up small spills. Report
significant spills to the Storm Water Protection
Program and/or the appropriate spill response
agencies immediately.
Write and keep current a spill response plan.
Ensure that employees are trained on the
elements of the plan.
Keep rags, damp mops and absorbents readily
accessible. Dispose of waste properly.
Employee Training
Discuss and distribute information on storm
water pollution prevention during employee
training sessions and at employee meetings.
Post good housekeeping tips and reminders on
employee bulletin boards.
Inform subcontractors about the new storm
water requirements and their responsibilities.
Storm Water HQTIine; 760-602-2 799
stormwater@cl.carlsbad.ca.us
Did,you know that storm drains are
:NoTggnnootod to onnitary oowor
yterA and treatment plants?
;The primary purpose of storm drains
lLueany.ialriwaLer away from
developed areas to prevent flooding.
'Untreated storm water and the
polldtàhts it carries, flow directly into
creeks,.lagoons and the ocean.
:lnrécent years, sources of water
pollution like industrial waters from
factpries have been greatly reduced.
However now, the majority of water
pállution occurs from things like cars
leaking oil fertilizers from farms and
gardens failing septic tanks pet
waste and residential car washing into
ih'estorrTi drains and into the ocean
and waterways.
All 'these sources add up to a pollution
problem! But each of us can do small
things to help clean up our water and
that adds up to? pollution solution'
What's the problem with fertilizers
and po3ticide3?
Fertilizer isn't a prohl?m-11' it's used
carefully. If you use too much
iertilier Or apply it at the wrong time,
it can easily wash off your lawn or
garden into storm drains and then
flow untreated into lakes or streams.
Just like in your garden, fertilizer in
lagoons and streams makes plants
grow. In water bodies, extra fertilizer
can mean extra algae and aquatic
olant growth. Too much algae harms
water quality and makes boating,
fishing and swimming unpleasant. As
algae decay, they use up oxygen in
the water that fish and other wildlife
need.
Fertilizer photo is used courtesy
Qf the Water Quality Consortium.
a cooperative vqn ti4irg between
the Washington State Department
of Fcnlngy King County and the
cities of Bellevue, Seattle and
Tacoma.
o IA
'Prote'°
0
City of Carlsbad
1 635 Faraday Avenue
Carlsbad CA 92008
www.cl.carlsbad.ca.us
Printed on recycled paper
Ii!
Having a clean environment is of
primary importance for our health and
èconorriy. Clean waterways provide
rnmercial opportunities, recreation,
fish habitat and add beauty to our
landscape. YOU can help keep our
creeks, lagoons and ocean clean by
applying the following tips:
Don't blow or rake leaves and other
yard waste into the street or gutter.
Recycle yard waste or start your own
compost pile.
' Don't over irrigate. Use drip
irrigation, soaker hoses or micro-
spray system and water early in the
morning.
If you have a spray head sprinkler
system, consider adjusting your
watering method to a cycle and
soak. Instead of watering for 15
minutes straight, break up the
4
session into 5 minute intervals
allowing water to soak in before the
next application.
Keep irrigation systems well-
maintained and water only when
needed to save money and prevent
over-watering. -
Use fertilizers and pesticides
sparingly.
Have your soil tested to determine
the nutrients needed to maintain a
healthy lawn.
Consider using organic fertilizers—
they release nutrients more slowly.
Leave mulched grass clippings on
the lawn to act as a natural fertilizer
Use pesticides only when absolutely
necessary. Use the least toxic
product intended to target a specific
pest, such as insecticidal soaps,
boric acid, etc. Always read the label
and use only as directed.
Use predatory insects to control
harmful pests when possible.
Properly dispose of unwanted
pesticides and fertilizers at
Household Hazardous Waste
collection facilities.
For more information on
landscape irrigation, please
call 760-438-2722.
Master Gardeners
San Diego County has a
Master Gardener program
through the University of
California Cooperative
Extension. Master
Gardeners can provide good information
about dealing with specific pests and
plants. You may call the Master
Gardener Hotline at 858-694-2860 or
check out their website at
www.mastergardenerssandieqo.org.
The hotline is staffed Monday—Friday;
9 am-3 pm, by experienced gardeners
who are available to answer specific
questions. Information from Master
Gardeners is free to the public.
............................................
Parking/Storage Area Maintenance SC-43
Description
Parking lots and storage areas can contribute a number of
sub5tances, such as trash, suspended solids, hydrocarbons, oil
and grc.ase, and heavy metals that can enter receiving waters
througlk stormwater runoff or non-stormwater discharges. The
protocols in this fact sheet are intended to prevent or reduce the
discarge of pollutants from parking/storage areas and include
using good housekeeping practices, following appropriate
cleaaing BMPs, and training employees.
Approach
The goal of this program is to ensure stormwater pollution
preven:ion practices are considered when conducting activities
on a a:ound parking areas and storage areas to reduce potent-al
for pollutant discharge to receiving waters. Successful
imp .enientation depends on effective training of employees on
app: icable BMPs and general pollution prevention strategies and
obj€cties.
Pot!u lion Prevention
Encourage alternative designs and maintenance strategies for
:mpervious parking lots. (See New Development and
3edevelopment BMP Handbook)
ii<e€p accurate maintenance logs to evaluate BMP
:mplementation.
Objectives
Cover
Contain
Educate
Reduce/Minimize
Product Substitution
Targeted Constituents
Sediment I,
Nutrients
Trash I
Metals
Bacteria
Oil and Grease /
Organics /
k
St
SQA
ornia
ormwater
Quality
Association
Janu3ry 2003 California Stormwater BMP Handbock 1 of 4
Industrial and Cornmerciall
www.cabmphandbooks.com
SC-43 Parking/Storage Area Maintenance
Suggested Protocols
General
• Keep the parking and storage areas clean and orderly. Remove debris in a timely fashion.
Allow sheet runoff to flow into biofilters (vegetated strip and swale) and/or infiltration
devices.
Utilize sand filters or oleophilic collectors for oily waste in low quantities.
Arrange rooftop drains to prevent drainagedirectly onto paved surfaces.-
Design lot to include semi-permeable hardscape.
Discharge soapy water remaining in mop or wash buckets to the sanitary sewer through a
sink, toilet, clean-out, or wash area with drain.
Controlling Litter
Post "No Littering" signs and enforce anti-litter laws.
Provide an adequate number of litter receptacles.
Clean out and cover litter receptacles frequently to prevent spillage.
Provide trash receptacles in parking lots to discourage litter.
Routinely sweep, shovel, and dispose of litter in the trash.
Surface Cleaning
Use dry cleaning methods (e.g., sweeping, vacuuming) to prevent the discharge of pollutants
into the stormwater conveyance system if possible.
Establish frequency of public parking lot sweeping based on usage and field observations of
waste accumulation.
Sweep all parking lots at least once before the onset of the wet season.
Follow the procedures below if water is used to clean surfaces:
- Block the storm drain or contain runoff.
- Collect and pump wash water to the sanitary sewer or discharge to a pervious surface.
Do not allow wash water to enter storm drains.
- Dispose of parking lot sweeping debris and dirt at a landfill.
Follow the procedures below when cleaning heavy oily deposits:
- Clean oily spots with absorbent materials.
- Use a screen or filter fabric over inlet, then wash surfaces.
2 of 4 California Stormwater BMP Handbook January 2003
Industrial and Commercial
www.cabmphandbooks.com
Parking/Storage Area Maintenance SC-43
- Do not allow discharges to the storm drain.
- Vacuum/pump discharges to a tank or discharge to sanitary sewer.
- Appropriately dispose of spilled materials and absorbents.
Surface Repair
Preheat, transfer or load hot bituminous material away from storm drain inlets.
Apply concrete, asphalt, and seal coat during dry weather to prevent contamination from
contacting stormwater runoff.
Cover and seal nearby storm drain inlets where applicable (with waterproof material or
mesh) and manholes before applying seal coat, slurry seal, etc. Leave covers in place until
job is complete and all water from emulsified oil sealants has drained or evaporated. Clean
any debris from these covered manholes and drains for proper disposal.
Use only as much water as necessary for dust control, to avoid runoff.
Catch drips from paving equipment that is not in use with pans or absorbent material placed
under the machines. Dispose of collected material and absorbents properly.
Inspection
Have designated personnel conduct inspections of parking facilities and stormwater
conveyance systems associated with parking facilities on a regular basis.
Inspect cleaning equipment/sweepers for leaks on a regular basis.
Training
Provide regular training to field employees and/or contractors regarding cleaning of paved
areas and proper operation of equipment.
• Train employees and contractors in proper techniques for spill containment and cleanup.
Spill Response and Prevention
Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date.
Place a stockpile of spill cleanup materials where it will be readily accessible or at a central
location.
Clean up fluid spills immediately with absorbent rags or material.
Dispose of spilled material and absorbents properly.
Other Considerations
Limitations related to sweeping activities at large parking facilities may include high equipment
costs, the need for sweeper operator training, and the inability of current sweeper technology to
remove oil and grease.
January 2003 California Stormwater BMP Handbook 3 of 4
Industrial and Commercial
www.cabmphandbooks.com
SC-43 Parking/Storage Area Maintenance
Requirements
Costs
Cleaning/sweeping costs can be quite large. Construction and maintenance of stormwater
structural controls can be quite expensive as well.
Maintenance
Sweep parking lot regularly to minimize cleaning with water.
• Clean out oil/water/sand separators regularly, especially after heavy storms.
Clean parking facilities regularly to prevent accumulated wastes and pollutants from being
discharged into conveyance systems during rainy conditions.
Supplemental Information
Further Detail of the BMP
Surface Repair
Apply concrete, asphalt, and seal coat during dry weather to prevent contamination from
contacting stormwater runoff. Where applicable, cover and seal nearby storm drain inlets (with
waterproof material or mesh) and manholes before applying seal coat, slurry seal, etc. Leave
covers in place until job is complete and all water from emulsified oil sealants has drained or
evaporated. Clean any debris from these covered manholes and drains for proper disposal.
Only use only as much water as is necessary for dust control to avoid runoff.
References and Resources
California's Nonpoint Source Program Plan http://www.swrcb.ca.gov/nps/index.html
Clark County Storm Water Pollution Control Manual
htlp://www.co.clark.wa.us/pubworks/blnpman.pdf
King County Storm Water Pollution Control Manual http://dnr.metrokc.gov/wlr/dss/spcm.htm
Pollution from Surface Cleaning Folder. 1996. Bay Area Stormwater Management Agencies
Association (BASMAA). http://www.basmaa.org/
Oregon Association of Clean Water Agencies. Oregon Municipal Stormwater Toolbox for
Maintenance Practices. June 1998.
Santa Clara Valley Urban Runoff Pollution Prevention Program http://www.scvurpnp.org
The Storm Water Managers Resource Center http://www.stormwatercenter.net/
4 of 4 California Stormwater BMP Handbook January 2003
Industrial and Commercial
www.cabmphandbooks.com
Efficient irrigation SD-12
Design Objectives
Maximize Infiltration
I1 Provide Retention
El Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Description . .
Irrigation water provided to landscaped areas niay resi-t in excess irrigation wateibeing
conveyed into stormwatr drainage systems. -.
Approach 1
Project plan digns fcr development and redevebpmerc:hoiild include application methods of
irrigation wa:er that minimize runoff of excess irrigation -Rater into the stormwater conveyance.• system. -
Suitable AplicatEons
Appropriate applicaticns include residential, c0m11e]Ki&l.md industrial areas planned for
dvelopmentor redevelopment. (Detached re:idmtial 4mgle-farnily homes are typically
excluded from this requirement.) * -
Design Considerations
Designing New Installations - .
The following method: lo reduce excessive irrigat.on :i-..i:ioff should be considered, and
incorporated and imp'emented where determhecl appio1e and feasible by the Permittee:
Employ r -triggred shutoff devices to prevent hr tioii after precipitation.
Design ir:igation stems to each landscape area ific water requirements.
Include design feaawing flow reducers or :siauiffv3Iv .
triggeredbj' a preure drop to controlwater Loss inIlI e'ven't . of broker sprinkler lieads or lines.
Implement Iandscaç e plans consistent wi± Count' .:xi City -
water cor.srvation ieso1utions, which may include poviskn
of water esors, programmable irrigation :imes (to: short -
cycles), e--C.
-
QAnT ASLAIVIAtIOV
Jnuary 2003 California Storniat,r BM' -fa idbcrk 1 of 2
New DevelopmEn: ard Recbpment
www.cabmpiardbo&s..m
SD-12 Efficient Irrigation
Design timing and application methods of irrigation water to minimize the runoff of excess
irrigation water into the storm water drainage system.
Group plants with similar water requirements in order to reduce excess irrigation runoff and
promote surface filtration. Choose plants with low irrigation requirements (for example,
native or drought tolerant species). Consider design features such as:
- Using mulches (such as wood chips or bar) in planter areas without ground cover to
minimize sediment in runoff
- Installing appropriate plant materials for the location, in accordance with amount of
sunlight and climate, and use native plant materials where possible and/or as
recommended by the landscape architect
- Leaving a vegetative barrier along the property boundary and interior watercourses, to
act as a pollutant filter, where appropriate and feasible
- Choosing plants that minimize or eliminate the use of fertilizer or pesticides to sustain
growth
Employ other comparable, equally effective methods to reduce irrigation water runoff
Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior construction, and land disturbing activities with structural or
impervious surfaces. The definition of" redevelopment" must be consulted to determine
whether or not the requirements for new development apply to areas intended for
redevelopment. If the definition applies, the steps outlined under "designing new installations"
above should be followed.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, February 14, 2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft February 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
2 of 2 California Stormwatr BMP Handbook January 2003
New Development and Redevelopment
www.cabmphandbooks.com
Storm Drain Signage SD-13
Design Objectives
Maximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Description
Waste materials dumped into ;torm drain inlets can have severe impacts on receiving and
ground waters. Postng notices regarding discharge prohibitions at storm drain inlets can
prevent waste dimpng. Storm drain signs and stencils are highly visible source controls that
are typically placed ifirectty adjacent to storm drain inlets.
Approach
The stencil or aEixecL sign contains a brief statement that prohibits dumping of improper
materials into the uran ininoffcorveyance system. Storm drain messages have become a
popular method of £ertir.g the pul: lie about the effects of and the prohibitions against waste
disposal.
Suitable Applications
Stencils and signs alert t1e pulic to the destination of pollutants discharged to the storm drain.
Signs are appro-)riat:B in residenti&, commercial, and industrial areas, as well as any other area
where contributions or dumping tc storm drains is likely.
Design Cons der.atians
Storm drain message markers or placards are recommended at all storm drain inlets within the
boundary of a development projeci. The marker should be placed in clear sight facing toward
anyone approaching the inlet Eom either side. All storm drain inlet locations should be
identified on the development site map.
Designing N.v ThstaAlations
The following rnethc ds shoukL be considered for inclusion in ihe
project design and siaow on projeci plans:
Provide ster.cilrng or abeling af all storm drain inlets and
catch basins, constructed or modified, within the project area
with prohib:tive language.. Exanples include "NO DUMPNG
(Al .11 ll'.l.', ,l ll.l../.l ll
8lA AA'CI(i lCl
January 2003 CIiFornia Stormwater BM Handbook 1 of 2
New- Development and ReveIopn-.ent
www.cabmphandbooks.com
SD-13 Storm Drain Signage
- DRAINS TO OCEAN" and/or other graphical icons to discourage illegal dumping.
Post signs with prohibitive language and/or graphical icons, which prohibit illegal dumping
at public access points along channels and creeks within the project area.
Note - Some local agencies have approved specific signage and/or storm drain message placards
for use. Consult local agency stormwater staff to determine specific requirements for placard
types and methods of application.
Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior construction, and land disturbing activities with structural or
impervious surfaces. If the project meets the definition of "redevelopment", then the
requirements stated under" designing new installations" above should be included in all project
design plans.
Additional Information
Maintenance Considerations
Legibility of markers and signs should be maintained. If required by the agency with
jurisdiction over the project, the owner/operator or homeowner's association should enter
into a maintenance agreement with the agency or record a deed restriction upon the
property title to maintain the legibility of placards or signs.
Placement
Signage on top of curbs tends to weather and fade.
Signage on face of curbs tends to be worn by contact with vehicle tires and sweeper brooms
Supplemental Information
Examples
Most MS4 programs have storm drain signage programs. Some MS4 programs will provide
stencils, or arrange for volunteers to stencil storm drains as part of their outreach program.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, February 14, 2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft February 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
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Trash Storage Areas SD-32
Description
Trash storage areas are areas where a trash receptacle (s) are
located for use as a repository for solid wastes. Stormwater
runoff from areas where trash is stored or disposed of can be
polluted. In addition, loose trash and debris can be easily
transported by water or wind into nearby storm dram inlets,
channels, and/or creeks. Waste handling operations that may be
sources of stormwater pollution include dumpsters, litter control,
and waste piles.
Approach
This fact sheet contains details on the specific measures required
to prevent or reduce pollutants in stormwater runoff associated
with trash storage and handling. Preventative measures
including enclosures, containment structures, and impervious
pavements to mitigate spills, should be used to reduce the
likelihood of contamination.
Suitable Applications
Design Objectives
Maximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Appropriate applications include residential, commercial and industrial areas planned for
development or redevelopment. (Detached residential single-family homes are typically
excluded from this requirement.)
Design Considerations
Design requirements for waste handling areas are governed by Building and Fire Codes, and by
current local agency ordinances and zoning requirements. The design criteria described in this
fact sheet are meant to enhance and be consistent with these code and ordinance requirements.
Hazardous waste should be handled in accordance with legal requirements established in Title
22, California Code of Regulation.
Wastes from commercial and industrial sites are typically hauled by either public or commercial
carriers that may have design or access requirements for waste storage areas. The design
criteria in this fact sheet are recommendations and are not intended to be in conflict with
requirements established by the waste hauler. The waste hauler should be contacted prior to the
design of your site trash collection areas. Conflicts or issues should be discussed with the local
agency.
Designing New Installations
Trash storage areas should be designed to consider the following structural or treatment control
BMPs:
Design trash container areas so that drainage from adjoining
roofs and pavement is diverted around the area(s) to avoid
run-on. This might include berming or grading the waste
handling area to prevent run-on of stormwater.
Make sure trash container areas are screened or walled to
prevent off-site transport of trash.
CA AC \IA IA.v.:I}:IC
Qfl.AIT'
January 2003 California StormwatrBMP Handbook 1 of 2
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SD-32 Trash Storage Areas
. Use lined bins or dumpsters to reduce leaking of liquid waste.
Provide roof, awnings, or attached lids on all trash containers to minimize direct
precipitation and prevent rainfall from entering containers.
Pave trash storage areas with an impervious surface to mitigate spills.
Do not locate storm drains in immediate vicinity of the trash storage area.
Post signs on all dumpsters informing users that hazardous materials are not to be disposed
of therein.
Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior construction, and land disturbing activities with structural or
impervious surfaces. The definition of" redevelopment" must be consulted to determine
whether or not the requirements for new development apply to areas intended for
redevelopment. If the definition applies, the steps outlined under "designing new installations"
above should be followed.
Additional Information
Maintenance Considerations
The integrity of structural elements that are subject to damage (i.e., screens, covers, and signs)
must be maintained by the owner/operator. Maintenance agreements between the local agency
and the owner/operator may be required. Some agencies will require maintenance deed
restrictions to be recorded of the property title. If required by the local agency, maintenance
agreements or deed restrictions must be executed by the owner/operator before improvement
plans are approved.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, February 14, 2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft February 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
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Targeted Constituents
R1 Sediment
21 Nutrients A
El Trash
E1 Metals
I?i Bacteria U
I?! Oil and Grease
Ii Organics .
Legend (Remo val Effectiveness)
Low • High
A Medium
Bioretention TC-32
Design Considerations
Soil for Infiltration
Tributary Area
Slope
Aesthetics
Environmental Side-effects
Descripi ion
The bioretention best management practice (F MF) functic.ns as a
soil and jnt-based fliration device that renveE pollutants-
through a wariety afphysieal, biological, and (1:errical trea:melt
processes.. These facili:ies normally con&st ofagiass buffer
strip, san] bed, ponding area, organic layer or mulch layer
planting soil, and 1ants. The runofE's velocity is reduced Iy
passing o.rr or thrug1 buffer strip and ibs&:ueatly distributed
evenly alc mg a ponding area. Exfiltrtion of thE stored watr in
the bioret€ntion area planting soil ir.to th unsEerling soils
occurs ove: a periol of days.
California Expie.ce
None documented. Bio:-etention has been used as a stormwatri
BMP since 1992. In addition to Prine George Cc.unty, MD and
Alexandri34, VA, bioretentinn has been used suces;thhly atiiran
and subuiban areas. in Montgomery CounLy, 1VI); Baltimore
County, D; Chesterfield County, VA; Prince ".illrn County,
VA; Smith Mountain Lake State Park VA, and ar:i NC.
Advantages
Bioreteation providEs stormwater tre1:rneirrtlt enharces
the qu.ity of dcwnstream water odias by I.mDorarily
storing runoff in the BMP and re'easing it cer a period of
four days to the receiving water (EPA, iL99
The vtation prov:des shade and wird brE 3ks, absorbs
noise, and improves an area's landscal.
Limitations
The bio:etention BMP is not reconmellded for areas with
slopes greater than o% or where mature tree rEmoval woukl
I. I II II(\IA :. F *ik'.VAI III
/cs.. fl,,
January 2003 California SIormr BMP Hanthok 1 of 8
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TC-32 Bioretention
be required since clogging may result, particularly if the BMP receives runoff with high
sediment loads (EPA, 1999).
Bioretention is not a suitable BMP at locations where the water table is within 6 feet of the
ground surface and where the surrounding soil stratum is unstable.
By design, bioretention BMPs have the potential to create very attractive habitats for
mosquitoes and other vectors because of highly organic, often heavily vegetated areas mixed
with shallow water.
. In cold climates the soil may freeze, preventing runoff from infiltrating into the planting soil.
Design and Sizing Guidelines
The bioretention area should be sized to capture the design storm runoff.
In areas where the native soil permeability is less than 0.5 in/hr an underdrain should be
provided.
Recommended minimum dimensions are 15 feet by 40 feet, although the preferred width is
25 feet. Excavated depth should be 4 feet.
Area should drain completely within 72 hours.
Approximately 1 tree or shrub per 50 ft2 of bioretention area should be included.
Cover area with about 3 inches of mulch.
Construction/Inspection Considerations
Bioretention area should not be established until contributing watershed is stabilized.
Performance
Bioretention removes stormwater pollutants through physical and biological processes,
including adsorption, filtration, plant uptake, microbial activity, decomposition, sedimentation
and volatilization (EPA, 1999). Adsorption is the process whereby particulate pollutants attach
to soil (e.g., clay) or vegetation surfaces. Adequate contact time between the surface and
pollutant must be provided for in the design of the system for this removal process to occur.
Thus, the infiltration rate of the soils must not exceed those specified in the design criteria or
pollutant removal may decrease. Pollutants removed by adsorption include metals, phosphorus,
and hydrocarbons. Filtration occurs as runoff passes through the bioretention area media, such
as the sand bed, ground cover, and planting soil.
Common particulates removed from stormwater include particulate organic matter,
phosphorus, and suspended solids. Biological processes that occur in wetlands result in
pollutant uptake by plants and microorganisms in the soil. Plant growth is sustained by the
uptake of nutrients from the soils, with woody plants locking up these nutrients through the
seasons. Microbial activity within the soil also contributes to the removal of nitrogen and
organic matter. Nitrogen is removed by nitrifying and denitrifying bacteria, while aerobic
bacteria are responsible for the decomposition of the organic matter. Microbial processes
require oxygen and can result in depleted oxygen le\rels if the bioretention area is not adequately
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Bioretention . TC-32
aerated. Sedimentation occurs in the swale or pondmg area as the velocity slows and solids fall
out of suspension.
The removal effectiveness of bioretention has been studied during field and laboratory studies
conducted by the University of Maryland (Davis et al, 1998). During these experiments,
synthetic stormwater runoff was pumped through several laboratory and field bioretention areas
to simulate typical storm events in Prince Georges County, MD. Removal rates for heavy metals
and nutrients are shown in Table 1.
Table 1 Laboratory and Estimated
Bioretention Davis et al (1998);
PGDER (1993)
Pollutant Removal Rate
Total Phosphorus 70-83%
Metals (Cu, Zn, Pb) 93-98%
TKN 68-80%
Total Suspended Solids 90%
Organics . 90%
Bacteria 90%
Results for both the laboratory and field experiments were similar for each of the pollutants
analyzed. Doubling or halving the influent pollutant levels had little effect on the effluent
pollutants concentrations (Davis et at 1998).
The microbial activity and plant uptake occurring in the bioretention area will likely result in
higher removal rates than those determined for infiltration BMPs.
Siting Criteria
Bioretention BMPs are generally used to treat stormwater from impervious surfaces at
commercial, residential, and industrial areas (EPA, 1999). Implementation of bioretention for
stormwater management is ideal for median strips, parking lot islands, and swales. Moreover,
the runoff in these areas can be designed to either divert directly into the bioretention area or
convey into the bioretention area by a curb and gutter collection system.
The best location for bioretention areas is upland from inlets that receive sheet flow from graded
areas and at areas that will be excavated (EPA, 1999). In order to maximize treatment
effectiveness, the site must be graded in such a way that minimizes erosive conditions as sheet
flow is conveyed to the treatment area Locations where a bioretention area can be readily
incorporated into the site plan without further environmental damage are preferred.
Furthermore, to effectively minimize sediment loading in the treatment area, bioretention only
should be used in stabilized drainage areas.
January 2003 California Stormwater BMP Handbook 3 of 8
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TC-32 Bioretention
Additional Design Guidelines
The layout of the bioretention area is determined after site constraints such as location of
utilities, underlying soils, existing vegetation, and drainage are considered (EPA, 1999). Sites
with loamy sand soils are especially appropriate for bioretention because the excavated soil can
be backflhled and used as the planting soil, thus eliminating the cost of importing planting soil.
The use of bioretention may not be feasible given an unstable surrounding soil stratum, soils
with clay content greater than 25 percent, a site with slopes greater than 20 percent, and/or a
site with mature trees that would be removed during construction of the BMP.
Bioretention can be designed to be off-line or on-line of the existing drainage system (EPA,
1999). The drainage area for a bioretention area should be between o.i and 0.4 hectares (0.25
and 1.0 acres). Larger drainage areas may require multiple bioretention areas. Furthermore,
the maximum drainage area for a bioretention area is determined by the expected rainfall
intensity and runoff rate. Stabilized areas may erode when velocities are greater than 5 feet per
second (1.5 meter per second). The designer should determine the potential for erosive
conditions at the site.
The size of the bioretention area, which is a function of the drainage area and the runoff
generated from the area is sized to capture the water quality volume.
The recommended minimum dimensions of the bioretention area are 15 feet (4.6 meters) wide
by 40 feet (12.2 meters) long; where the minimum width allows enough space for a dense,
randomly-distributed area of trees and shrubs to become established. Thus replicating a natural
forest and creating a microclimate, thereby enabling the bioretention area to tolerate the effects
of heat stress, acid rain, runoff pollutants, and insect and disease infestations which landscaped
areas in urban settings typically are unable to tolerate. The preferred width is 25 feet (7.6
meters), with a length of twice the width. Essentially, any facilities wider than 20 feet (6.1
meters) should be twice as long as they are wide, which promotes the distribution of flow and
decreases the chances of concentrated flow.
In order to provide adequate storage and prevent water from standing for excessive periods of
time the ponding depth of the bioretention area should not exceed 6 inches (15 centimeters).
Water should not be left to stand for more than 72 hours. A restriction on the type of plants that
can be used may be necessary due to some plants' water intolerance. Furthermore, if water is
left standing for longer than 72 hours mosquitoes and other insects may start to breed.
The appropriate planting soil should be backfilled into the excavated bioretention area. Planting
soils should be sandy loam, loamy sand, or loam texture with a clay content ranging from 10 to
25 percent.
Generally the soil should have infiltration rates greater than 0.5 inches (1.25 centimeters) per
hour, which is typical of sandy barns, loamy sands, or loams. The pH of the soil should range
between 5.5 and 6.5, where pollutants such as organic nitrogen and phosphorus can be adsorbed
by the soil and microbial activity can flourish. Additional requirements for the planting soil
include a 1.5 to 3 percent organic content and a maximum 500 ppm concentration of soluble
salts.
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Bioretention TC-32
Soil tests should be performed for every 500 cubic yards (382 cubic meters) of planting soil,
with the exception of pH and organic content tests, which are required only once per
bioretention area (EPA, 1999). Planting soil should be 4 inches (10.1 centimeters) deeper than
the bottom of the largest root ball and 4 feet (1.2 meters) altogether. This depth will provide
adequate soil for the plants' root systems to become established, prevent plant damage due to
severe wind, and provide adequate moisture capacity. Most sites will require excavation in
order to obtain the recommended depth.
Planting soil depths of greater than 4 feet (1.2 meters) may require additional construction
practices such as shoring measures (EPA, 1999). Planting soil should be placed in 18 inches or
greater lifts and lightly compacted until the desired depth is reached. Since high canopy trees
may be destroyed during maintenance the bioretention area should be vegetated to resemble a
terrestrial forest community ecosystem that is dominated by understory trees. Three species
each of both trees and shrubs are recommended to be planted at a rate of 2500 trees and shrubs
per hectare (i000 per acre). For instance, a 15 foot (4.6 meter) by 40 foot (12.2 meter)
bioretention area (600 square feet or 55.75 square meters) would require 14 trees and shrubs.
The shrub-to-tree ratio should be 2:1 to : 1.
Trees and shrubs should be planted when conditions are favorable. Vegetation should be
watered at the end of each day for fourteen days following its planting. Plant species tolerant of
pollutant loads and varying wet and dry conditions should be used in the bioretention area.
The designer should assess aesthetics, site layout, and maintenance requirements when
selecting plant species. Adjacent non-native invasive species should be identified and the
designer should take measures, such as providing a soil breach to eliminate the threat of these
species invading the bioretention area. Regional landscaping manuals should be consulted to
ensure that the planting of the bioretention area meets the landscaping requirements
established by the local authorities. The designers should evaluate the best placement of
vegetation within the bioretention area. Plants should be placed at irregular intervals to
replicate a natural forest. Trees should be placed on the perimeter of the area to provide shade
and shelter from the wind. Trees and shrubs can be sheltered from damaging flows if they are
placed away from the path of the incoming runoff. In cold climates, species that are more
tolerant to cold winds, such as evergreens, should be placed in windier areas of the site.
Following placement of the trees and shrubs, the ground cover and/or mulch should be
established. Ground cover such as grasses or legumes can be planted at the beginning of the
growing season. Mulch should be placed immediately after trees and shrubs are planted. Two
to 3 inches (5 to 7.6 cm) of commercially-available fine shredded hardwood mulch or shredded
hardwood chips should be applied to the bioretention area to protect from erosion.
Maintenance
The primary maintenance requirement for bioretention areas is that of inspection and repair or
replacement of the treatment area's components. Generally, this involves nothing more than the
routine periodic maintenance that is required of any landscaped area Plants that are
appropriate for the site, climatic, and watering conditions should be selected for use in the
bioretention cell. Appropriately selected plants will aide in reducing fertilizer, pesticide, water,
and overall maintenance requirements. Bio retention system components should blend over
time through plant and root growth, organic decomposition, and the development of a natural
January 2003 California Stormwatr BMP Handbook 5 of 8
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TC-32 Bioretention
soil horizon. These biologic and physical processes overtime will lengthen the facility's life span
and reduce the need for extensive maintenance.
Routine maintenance should include a biannual health evaluation of the trees and shrubs and
subsequent removal of any dead or diseased vegetation (EPA, 1999). Diseased vegetation should be treated as needed using preventative and low-toxic measures to the extent possible.
BMPs have the potential to create very attractive habitats for mosquitoes and other vectors
because of highly organic, often heavily vegetated areas mixed with shallow water. Routine
inspections for areas of standing water within the BMP and corrective measures to restore
proper infiltration rates are necessary to prevent creating mosquito and other vector habitat. In
addition, bioretention BMPs are susceptible to invasion by aggressive plant species such as
cattails, which increase the chances of water standing and subsequent vector production if not
routinely maintained.
In order to maintain the treatment area's appearance it may be necessary to prune and weed.
Furthermore, mulch replacement is suggested when erosion is evident or when the site begins to
look unattractive. Specifically, the entire area may require mulch replacement every two to
three years, although spot mulching may be sufficient when there are random void areas. Mulch
replacement should be done prior to the start of the wet season.
New Jersey's Department of Environmental Protection states in their bioretention systems
standards that accumulated sediment and debris removal (especially at the inflow point) will
normally be the primary maintenance function. Other potential tasks include replacement of
dead vegetation, soil pH regulation, erosion repair at inflow points, mulch replenishment,
unclogging the underdrain, and repairing overflow structures. There is also the possibility that
the cation exchange capacity of the soils in the cell will be significantly reduced over time.
Depending on pollutant loads, soils may need to be replaced within 5-10 years of construction
(LID, 2000).
Cost
Construction Cost
Construction cost estimates for a bioretention area are slightly greater than those for the
required landscaping for a new development (EPA, 1999). A general rule of thumb (Coffinan,
1999) is that residential bioretention areas average about $3 to $4 per square foot, depending on
soil conditions and the density and types of plants used. Commercial, industrial and
institutional site costs can range between $io to $40 per square foot, based on the need for
control structures, curbing storm drains and underdrains.
Retrofitting a site typically costs more, averaging $6,00 per bioretention area. The higher costs
are attributed to the demolition of existing concrete, asphalt, and existing structures and the
replacement of fill material with planting soil. The costs of retrofitting a commercial site in
Maryland, Kettering Development, with 15 bioretention areas were estimated at $11i,60o.
In any bioretention area design, the cost of plants varies substantially and can account for a
significant portion of the expenditures. While these cost estimates are slightly greater than
those of typical landscaping treatment (due to the increased number of plantings, additional soil
excavation, backfill material, use ofunderdrains etc.), those landscaping expenses that would be
required regardless of the bioretention installation should be subtracted when determining the
net cost.
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Bioretention TC-32
Perhaps of most importance, however, the cost savings compared to the use of traditional
structural stormwater conveyance systems makes bioretention areas quite attractive financially.
For example, the use of bioretention can decrease the cost required for constructing stormwater
conveyance systems at a site. A medical office building in Maryland was able to reduce the
amount of storm drain pipe that was needed from 800 to 230 feet - a cost savings of $24,000
(PGDER, 1993). And a new residential development spent a total of approximately $ioo,000
using bioretention cells on each lot instead of nearly $400,000 for the traditional stormwater
ponds that were originally planned (Rappahanock,). Also, in residential areas, stormwater
management controls become a part of each property owner's landscape, reducing the public
burden to maintain large centralized facilities.
Maintenance Cost
The operation and maintenance costs for a bioretention facility will be comparable to those of
typical landscaping required for a site. Costs beyond the normal landscaping fees will include
the cost for testing the soils and may include costs for a sand bed and planting soil.
References and Sources of Additional Information
Coffman, L.S., R. Goo and R. Frederick, 1999: Low impact development: an innovative
alternative approach to stormwater management. Proceedings of the 26th Annual Water
Resources Planning and Management Conference ASCE, June 6-9, Tempe, Arizona
Davis, A.P., Shokouhian, M., Sharma, H. and Minami, C., "Laboratory Study of Biological
Retention (Bioretention) for Urban Stormwater Management," Water Env iron. Res., 73(l),5-14
(2001).
Davis, A.P., Shokouhian, M., Sharma, H., Minami, C., and Winogradoff, D. "Water Quality
Improvement through Bioretention: Lead, Copper, and Zinc," Water Environ. Res., accepted for
publication, August 2002.
Kim, H., Seagren, E.A., and Davis, A.P., "Engineered Bioretention for Removal of Nitrate from
Stormwater Runoff," WE1TEC 2000 Conference Proceedings on CDROM Research
Symposium, Nitrogen Removal, Session 19, Anaheim CA, October 2000.
Hsieh, C.-h. and Davis, A.P. "Engineering Bioretention for Treatment of Urban Stormwater
Runoff," Watersheds 2002, Proceedings on CDROM Research Symposium, Session 15, Ft.
Lauderdale, FL, Feb. 2002.
Prince George's County Department of Environmental Resources (PGDER), 1993. Design
Manual for Use of Bioretention in Stormwater Management. Division of Environmental
Management, Watershed Protection Branch. Landover, MD.
U.S. EPA Office of Water, 1999. Stormwater Technology Fact Sheet: Bioretention. EPA 832-F-
99-012.
Weinstein, N. Davis, A.P. and Veeramachaneni, R. "Low Impact Development (LID) Stormwater
Management Approach for the Control of Diffuse Pollution from Urban Roadways," 5th
International Conference Dffiise/Nonpoint Pollution and Watershed Management
Proceedings, C.S. Melching and Emre Alp, Eds. 2001 International Water Association
January 2003 California Stormwater BMP Handbook 7 of 8
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TC-32 Bioretention
PARKING LOT SHEET FLOW
CURBSTOPS I Jr
. .'t- ,- '.-;,R ..' .' '• '.rc- . !--STONEDIAPHFAGM
'..
GRASS FILTER
STRIP
..•....
OPTIONAL 4OUTLEF ...
. •oo SAND LAYER 144 - - I - —11, . ..... [4
GRAVEL CURTAIN
'CATCH
OVERFLOW
BASIN' -.. .-. -. .'
LL
'-"- DRAIN OVERFLOW
BERM
UNDERDRAFN COLLECTION SYSTEM PLAN VIEW
OPTIONAL SAND
FILTER LAYER
6' FONDING
2'-3' MULCH
4 PLANTING SOIL
FILTER FABRIC 0" PERFORATED
PIPE IN 8' GRAVEL
JACKET
TYPICAL SECTION PROFILE
Schematic of a Bio retention Facility (MDE, 2000)
8 of 8 California Stormwater BMP Handbook January 2003
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At lip IN
1jJe o
%
Storm Wat] i11 Program
Ar .
<__
A
TRASH
TrasIi and debris ,that the storm:dráii2system e&ituaUy 6i
Ar 4 polluting ourbeaches an4 waterwiys .,Trash not '-'
rT -0c _IroteG oniy pollutes ourwater and harmmarinehfe,. it ; U _______ " r -k 'can clog storm drains which results in floods during
rainy'weatlier. Best'ManagèntIPraetice'sorA Clean :BMPSäre Environment i. iñd oth llutiiti fiiiiieiithij
S.. '5 uuw . drains. 'Each of iis:can do ourpar tokeepstorin: ,..
' I i water clean Using BMPs adds upto a pollution
In the ON o Carlsbad DUMPSrIERS, I
sionn drains floiv directly Allrashniütbiplàded inside duiipsteir ihtainers tthtil it can be
lagoonsinto local creeks, hauled away Dumpsters should never be allowed overflow and
Ar - -' - should always bc kept oioseath ent'raiiiwtèr ,frnm entering. Never ,, I, 1pj S.'' ,,,' p1acehquidwas, leaky garbage bags, aid hazardous waste ma _
, dumpster. ortraskbi Routm1checkdumpsters for leaks and',!";, Pollutionrgti: ' immediately contact your trash disposal company ifleaks are found
, -1A cause huinan - _-.------- _. . .-. S
'I
SS,
('it, 'TRY IT DRY'
- . ' ....., . , ,,- ', S .' •, j Instead,of using a hose or pressure whing system,.try.a dry cleanup
- , method' Use mops brooms or wire lxushes to clean dumpste sidewalks ( V 4 buildings equipment pavement dnvways, or other imperviois surfaced V
. -. Use brooms àndabsorbents such as tlitt'sawdust or veimkulite.to"clean .)
:coines up small spills Sweep up around durhpsters and ther areas fi quently t ( lip
/A sources inchiding oil,fitel, Prevent trash from accumulating.
11JJI1J1IL1111 jSJ•• , S ' . ' . .5 . . . t' '
4, ONLY RAIN IN THE STORM DRAIN'
JJJJj Identif' and locate storm drams near four busmess or home where pollutauts could flow 1 "
- from your dumpster or trash bm ThçCdyhas stéhcils you can use o paintyour nearby 41 1 storm drain to let everyone know thit,water flows to the ocean If a storm4irain is on your
flrI 'IJItNkl(J private poerty, check it frequently id clean out any debris
JIWMU,I1i1W DIIIAr - J
RECYCLE! REcYcLE! RECYCLE!lip
Most trash and deb can be recycled and used for 0th4 purpces Items
A tn , such as cans, bottles newspaper office paper and cardboard can be recycled
a7ImII JiiliflKUVIl[ at sites throughout the City For infornation about recycling dj,portunitles?in' IJIJIl.. your area'cal1'1-8OOCLEAN-UF orvisit wwiv.1800CLEAN1JP.org - water qtialitly andfrffffr'._ ;' S S ' - .
.S '
A
I lip
Jii'lIII I , S
'SPILLS - ' - /,at 7(sj,, PJk(øI(IPfj . . .- S . . lip
If an accidental spill occurs immediateay use rags, a mop, or an absorbent id containment
I "P materials'to prevent liquids from dumpsters 'and trash bins from entering the '
storm dram Keep cleanup kits m places where they are easily accessible
Develop a spill response plan for youfbusmess and make sure -your
Ar employees know whát.tp,do when spills occur: The.City, can work with you - . ';
to develop a plan and BIviPs for your specific busmess
lip
For more information or to .ieport an illegal
discharge, please call 763-602-2799
TREATMENT VOLUME QUALITY CONSIDERATION
The treatment capacities for volume-based BMPs are calculated based on the runoff volume produced
from the 85% percentile storm event. The modified sand filter trenches will be provided to treat the runoff
from developed areas of the project site. The 85% percentile storm event is 0.70 for the project site
according to the San Diego County Hydrology Manual. The method used in calculating the treatment
volume is Method 1 outlined in the Carlsbad SUSMP.
Volume based BMPs shall be designed to mitigate (infiltrate, filter, or treat) the volume of runoff produced
from a 24 hour 85th percentile storm event, as determined from isopluvial maps contained in the County
of San Diego Hydrology Manual.
C = .85 (runoff coefficient)
P85% .70 (85% percentile storm volume for project site area)
Drainage Area 2
Drainage Area: A= 0.72
0.85 x .70 x 0.72 = .43 ac-in
= 0.036 ac-ft
= 1555 ft3
= WQV 1555 ft3
Drainage Area 3
Drainage Area: A= 0.32
0.85 x .70 x 0.32 = 0.19 ac-in
= 0.016 ac-ft
= 691 ft3
=WQV691 ft3
Drainage Area 4
Drainage Area: A= 0.32
0.85 x .70 x 0.32 = 0.19 ac-in
= 0.016 ac-ft
= 691 ft3
=WQV691 ft3
F Us S C 0 E
C N G I N C C R I N G
Irvine
San Diego
Inland Empire
Pnlm Springs
Modified Sand Filter Trench Sizing Per (CASQA TC-40) Using Darcy's Law
AF= (WQV x d) / [k x t x (h+d)]
A= Area of the filter bed
d= Depth of the FilterS Bed
k= coefficient of permeability of the filtering medium (ft/day)
t= time for the WQV to travel through the system
h= average water height above the sand bed (ft) or 1/2 maximum head
Modified Sand Filter Trench: Drainage Area 2
d = 3 feet
= 1 .67 days
h = 0.5 ft
k = 2.14 (Sand = 3.5 ft/day; Soil = 1.0 ft/day; Peat = 2.0 ft/day; Gravel = Assume no time)
AF= (1555 x 3) / [2.14 xl .67 x (3 + .651
AF = 357 ft2
The actual size of the filter trench area is 576 ft2 which is greater than the sized area of 357 ft2
Filter Pore Space
The pore space contained in the 3' deep filter medium relates to the porosity of the materials contained in the
filter. The porosity of the layers is as follows. Soil: 25% porosity; Peat: 80% porosity; Sand: 26% porosity;
Gravel: 23% porosity.
The filter can store 599 ft' of water as shown in the calculation below, based the 576 ft2 surface area.
Soil: 576 x .08 x 20% = 9 ft'
'p FUSCO
£ N G I N E F R I N 6
Irvine
San Diego
inland empire
Palm Springs
Peat: 576 x .66'x 80% = 304 ft3
Sand: 576 x 1.33 x 26% = 199 ft3
Gravel: 576 x .66 x 23% = 87 ft3
Total = 599 ft3
Modified Sand Filter Trench: Drainage Area 3
d = 3 feet
= 1 .67 days
h = 0.5 ft
k = 2.14 (Sand = 3.5 ft/day; Soil = 1.0 ft/day; Peat = 2.0 ft/day; Gravel = Assume no time)
AF= (691 x 3)/[2.14 xl .67 x(3 + .65]
A= 145 ft2
The actual size of the filter trench area is 672 ft2 which is greater than the sized area of 145 ft2.
Filter Pore Space
The pore space contained in the 3' deep filter medium relates to the porosity of the materials contained in the
filter. The porosity of the layers is as follows. Soil: 25% porosity; Peat: 80% porosity; Sand: 26% porosity;
Gravel: 23% porosity.
The filter can store 699 ft3 of water as shown in the calculation below, based the 672 ft2 surface area.
Soil: 672 x .08 x 20% = 11 ft3
Peat: 672 x .66'x 80% = 354 ft3
Sand: 672 x 1.33 x 26% = 232 ft3
Gravel: 672 x .66 x 23% = 102 ft3
Total = 699 ft3
11119.
toll
FUSC04/IE Son Diego
Iniand Empire
E N G I N £ E R I N 6 Palm Springs
Modified Sand Filter Trench: Drainage Area 4
d = 3 feet
= 1.67 days
h = 0.5 ft
k = 2.14 (Sand = 3.5 ft/day; Soil = 1.0 ft/day; Peat = 2.0 ft/day; Gravel = Assume no time)
A= (691 x3)/[2.14x 1.67x(3 + 1)
AF= 145 ft2
The actual size of the filter trench area is 621 ft2 which is greater than the sized area of 145 ft2.
Filter Pore Space
The pore space contained in the 3' deep filter medium relates to the porosity of the materials contained in the
filter. The porosity of the layers is as follows. Soil: 25% porosity; Peat: 80% porosity; Sand: 26% porosity;
Gravel: 23% porosity.
The filter can store 647 ft3 of water as shown in the calculation below, based the 621 ft2 surface area.
Soil: 621 x.08x20%= 10 ft3
Peat: 621 x .66'x 80% = 328 ft3
Sand: 621 xl.33x26%=215ft'
Gravel: 621 x .66 x 23% = 94 ft3
Total = 647 ft3
SUB-AREA 2
TOTAL AREA: 0.715 Ac.
IMPERVIOUS: 0.563 Ac.
SUB-AREA 5
PERVIOUS: 0.255 Ac.
IMPERVIOUS: 0.078 Ac.
SUAREA6 'S
TOTAL AREA: 0.039 Ac. I I
PERVIOUS: 0.039 Ac. I
IMPERVIOUS:0.0Ac. I
I I
--
I / ,
-------------
I
II'
TOWN GARDN
\\
ROAD / II ..'
I72o , I,
if
LEGEND
ITEM STANDARD DW& NO. SYMBOL
DRAINAGE SUB-ARC4
FLOW DIRECTION -
FLOW PATH
-i7
TOTAL AREA: 0.223Ac. ;1;11 1
IMPERVIOUS* 0 00 Ac
'
LU
0 TO TAL AREA: 0.315 Ac.
PERVIOUS: U.UDD MG.
SUB3 -AREA
IMPERVIOUS: 0.249 Ac.
_rx TOTAL AREA: 0.318 Ac.
PERVIOUS: 0.012 Ac.
IMPERVIOUS: 0.306 Ac.
284
POST DEVELOPMENT
DRAINAGE AREA MAP 20 10 0 20 40 60 I FINAL DRAINAGE REPORT FUSCOE GRAPHIC SCALE IN FEET BRESSI RANCH MEDICAL PLAZA
TOWN GARDEN ROAD & METROPOLITAN STREET I N S I N I I I I N S
PROJECT NUMBER 2591.02A 6390 Groonwith 0,fo, Suite 170
5C/LE 1*-20 Son Diego, C&ifon.io 92122
MI 858.554.1500 to. 858.597.0335 DATE: 03/05/08 ww.fu,oe.cm
511001 I OF I
Storm Intensity Calculation Sheet
Bressi Ranch Medical Plaza
5/8/2008
Storm Frequency Frequency 6hr. Storm Frequency 24hr. Storm P6/P24 Adjusted P6 Ic Intensity
(yr.) (in.) (in.) (in) (nun) (in/hi)
2 1.35 200 68% 1.30 15 1.69
5 150 280 58% 150 15 195
10 :. .1.85 . 3:25 . 57% 1.85 15 2.40
25 2.25 4.00 56% 2.25 15 2.92
50 250 4.50. 56% 250 15 324
100 280 500 56% 280 60 149
Pm Reduction
100 YEAR
.Triänglo
Conlrlbuttng Area C Area )ac) Ic (rein) Qlth Volume
Sub-Area 1 0.38 0.28 7 0.63 N/A
Sub-Area 2 0.76 0.72 5 4.04 3633
Sub-Area 3 0.85 0.32 5 2.01 1806
Sub-Area 4 0.76 0.32 5 1.79 1615
Sub-AreaS 0.50 0.27 5 1.00 N/A
Sub-Area 6 0.35 0.04 5 0.10 N/A
Total Flow to Existing System (cfs) 8.57
Total Bypass Flow Ids) 1.00
2 YEAR
Tnongu)ar
Contributing Area C Area lac)' Ic (mm) Q2 Volume
Sub-Area 1 0.38 0.28 7 0.29 N/A
Sub-Area 2 0.76 0.72 5 1.87 1687
Sub-Area 3 0.85 0.32 5 0.93 838
Sub-Area 4 0.76 0.32 5 0.83 750
Sub-Area 5 0.50 0.27 5 0.46 N/A
Sub-Area 6 0.35 0.04 5 0.05 1 N/A
Total Flow to Existing System Ids) 3.98
Total Bypass Flow Ids) 0.46
10 YEAR
Triangular I
Contributing Area C Area (cc) Tc(min) Volume (I
Sub-Area 1 0.38 0.28 7 0.42 N/A
Sub-Area 2 0.76 0.72 5 2.67 2400
Sub-Area 3 0.85 0.32 5 1.33 1193
Sub-Area 4 0.76 0.32 5 1.19 1067
Sub-Area 5 0.50 0.27 5 0.66 N/A
Sub-Area 6 0.35 0.04 5 0.07 1 N/A
Total Flow to Existing System (cfs) 5.66
Total Bypass Flow Ids) 0.66
1:53 PM 5/13/2008
Post Reduction
Basin Volumes ft3
Basin 2 561
Basin 3 865
Basin 4 1 539
Contributing Area I C Area (ac.) I Tc (mm.) I Qieod.
Sub-Area 1 0.38 0.28 7 0.63
Sub-Area 2 0.76 0.72 7 3.25
Sub-Area 3 0.85 0.32 5 2.01
Sub-Area 4 0.76 0.32 5 1.79
Sub-AreaS 0.50 0.27 5 1.00
Sub-Area 6 0.35 0.04 5 0.10
Total Flow to Existing System (cfs) 779
Total Bypass Flow (cfs) 1.00
2 YEAR
Contributing Area I C I Area (oc.) I Tc (mm) I
Sub-Area 1 0.38 0.28 7 0.29
Sub-Area 2 0.76 0.72 10 1.20
Sub-Area 3 0.85 0.32 10 0.60
Sub-Area 4 0.76 0.32 18 0.36
Sub-Area 5 - 0.50 0.27 5 0.46
Sub-Area 6 0.35 0.04 - 5 0.05
Total Flow to Existing System (cfs) 2.50
Total Bypass Flow (cfs) 0.46
10 YEAR
Contributing Area C Area (cc) I Tc (mm) I Qio
Sub-Area 1 0.38 0.28 7 0.42
Sub-Area 2 0.76 0.72 8 1.97
Sub-Area 3 0.85 0.32 7 1.07
Sub-Area 4 0.76 0.32 10 0.76
Sub-Area 5 0.50 0.27 5 0.66
Sub-Area 6 0.35 0.04 5 0.07
Total Flow to Existing System (cfs) 4.28
Total Bypass Flow (cfs) 0.66
1:53PM 5/13/2008 ............................................
Basin Catcs
2 Year
Basin 2 Basin 3 Basin 4
Travel Time=3 min Travel Time=3 mm
Basin Volume= 561 ft3 Basin Volume= 865 ft3 Basin Volume= 1539 ft3 Time to Fill= 561/1.9= 5 min Time to Fill 865/2. 1 S= 7 min Time to Fill= 1539/2.0= 13 mm Q IN= l.9cfs QIN=O.9cfs QIN=0.8cfs Runoff Volume = 1687113 Runoff Volume = 838113 Runoff Volume = 750113 Spillover Volume= 1126 1t3 Spillover Volume= 1099 1t3 Spillover Volume= 310113
Addl Spillover Flow= 1.25 cfs Addl Spillover Flow= 1.2 cfs Addl Spillover Flow= 0.34 cfs
10 Year
Basin 2 -. Basin 3 Basin 4
Travel Time=3 min Travel Time=3 mm
Basin Volume= 561 ft3 Basin Volume= 865 1t3 Basin Volume= 1539113
Time to Fill= 561/2.7= 3 min Time to Fill= 865/3.3= 4 min Time to Fill= 1539/3.6= 7 mm QIN=2.7cfs Q IN= 1.3cfs Q IN= 1.2cfs Runoff Volume = 2400 1`13 Runoff Volume = 1193 ft3 Runoff Volume = 1067 ft3 Spillover Volume= 1839113 Spillover Volume= 2167113 Spillover Volume= 1695113 Addl Spillover Flow= 2.0 cfs Addl Spillover Flow= 2.4 cfs Addl Spillover Flow= 1.9 cfs
100 Year
Basin 2 Basin 3 Basin 4
Travel Time=3 min Travel Time=3 mm Basin Volume= 561 ft3 Basin Volume= 865 ft3 Basin Volume= 1539 ft3 Time to Fill= 561/4.0= 2 min Time to Fill 865/8.8= 2 min Time to Fill= 1539/11= 2 mm
Q IN=4.0 cfs Q lN=2.0 cfs 0 IN= 1.8 cfs Runoff Volume = 3633 ft3 Runoff Volume = 1806113 Runoff Volume = 1615 113 Spillover Volume= 3072113 Spillover Volume= 4013113 Spillover Volume= 4089 1t3 Addl Spillover Flow= 6.8 cfs Addl Spillover Flow= 8.9 cfs Addl Spillover Flow= 9 cfs
Travel Time
C),fD. Ti =
D=59 ft
5=4%
C=.72
Ti= 3 mm
1:53 PM 5/13/2008
LiiIi :Th
Wit
BIORETENTION MAINTENANCE INSPECTION FORM *
Facility Number: Date: Time:____________________
Subdivision Name: Watershed:_________________________________________________
Weather: Inspector(s):________________________________________________
Date of Last Rainfall: Amount: Inches Streets:____________________________________________________
Mapbook Location: GPS Coordinates:____________________________________________
Property Classification: Residential Government Commercial Other:________________ -
Confined Unconfined Barrel Size As-built Plan Available? Yes No
Is Facility Inspectable? Yes No Why? Comments Specific Location(s):________________________
Scoring Breakdown:
N/A = Not Applicable 1 =Monitor (potential for future problem exists) * Use open space in each section to furthe
N/I = Not Investigated 2 = Routine Maintenance Required explain scoring as needed
0 = Not a Problem 3 = Immediate Repair Necessary -
Outfall Channel(s) from Facility
Woody growth within 5' of outfall barrel N/A N/I 0 1 2 3
Outfall channel functioning - N/A N/I 0 1 2 3
Manholes, frames and covers N/A N/I 0 1 2 3
Released water undercutting outlet N/A N/I 0 1 2 3 -
Erosion N/A N/I 0 1 2 3
Displaced rip rap N/A N/I 0 1 2 3
Excessive sediment deposits N/A N/I 0 1 2 3
Other: N/A N/I 0 1 2 3
Outlet I Overflow Spillway
Woody growth or unauthorized plantings N/A N/I 0 1 2 3
Erosion or back cutting N/A N/I 0 1 2 3
Soft or boggy areas N/A N/I 0 1 2 3
Obstructions / debris N/A N/I 0 1 2 3
Filter
Existing as required No Yes
Sediment accumulation> 1" No Yes -
Ponding more than 2 days after rain No Yes
-
Vegetation N/A N/I 0 1 2 3
Depth & material of layers Depth: Material:
Sediment accumulation in soil bed N/A N/I 0 1 2 3 -
Oil/ chemical accumulation on soil bed N/A N/I 0 1 2 3
Filter fabric N/A N/I 0 1 2 3
Other: N/A N/I 0 i 2 3
N/A = Not Applicable 1 = Monitor for Future Repairs
N/I = Not Investigated 2 = Routine Repairs Needed
0 = Not a Problem 3 = Immediate Repair Needed Pagel of 4
BIORETENTION MAINTENANCE INSPECTION FORM
Underdrains
Broken N/A N/I 0 1 2 3
Daylighted N/A N/I 0 1 2 3
Clogging N/A N/I 0 1 2 3
Pretreatment
Maintenance access N/A N/I 0 1 2 3
Pretreatment a practice other than a stone diaphragm and/
or grass filter strip No Of so, (code) Yes
Stone diaphragm level N/A N/I 0 1 2 3
Stone diaphragm clogged with sediment/debris N/A N/I 0 1 2 3
Grass filter strip erosion N/A N/I 0 1 2 3
Evidence of short circuiting, rails/ gullies in filter strip No Yes
Level spreader N/A N/I 0 1 2 3
Other: N/A N/I 0 1 2 3
upland Characteristics
Excessive trash / debris N/A N/I 0 1 2 3
Bare soil present N/A N/I 0 1 2 3
Sand in parking lot N/A N/I 0 1 2 3
Inflow Points
Number of inflow pipes: Direction: N E W S
Endwalls, headwalls, end sections N/A N/I 0 1 2 3
Inlet/ outflow pipes N/A N/I 0 1 2 3
Discharge undercutting outlet or displacing rip-rap N/A N/I 0 1 2 3
Discharge water is causing outfall to erode N/A N/I 0 1 2 3
Sediment accumulation N/A N/I 1 0 1 2 3
Special Structures
Manhole access (steps, ladders) N/A N/I 0 1 2 3
Vehicular access N/A N/I 0 1 2 3
Concrete/masonry condition N/A N/I 0 1 2 3
Sediment / trash accumulation N/A N/I 0 1 2 3
Manhole lockable nuts N/A N/I 0 1 2 3
Miscellaneous
Encroachment in facility area and/or easement area by
buildings N/A N/I 0 1 2 3
Complaints from local residents N/A N/I 0 1 2 3
Graffiti N/A N/I 0 1 2 3
Public hazards N/A N/I 0 1 2 3
Were any pad locks cut and replaced No Yes How many?________________________
Other: N/A N/I 0 1 2 3
N/A = Not Applicable 1 = Monitor for Future Repairs
N/i = Not Investigated 2 = Routine Repairs Needed
0 = Not a Problem 3 = Immediate Repair Needed Page 2 of 4
BIORETENTION MAINTENANCE INSPECTION FORM
Overall Condition of Facility
Total number of concerns receiving a: (1) - Need Monitoring
- Routine Repair
- Immediate Repair Needed
Inspector's Summary
Pictures Clock/Degrees
N/A = Not Applicable 1 = Monitor for Future Repairs
N/I = Not Investigated 2 = Routine Repairs Needed
0 = Not a Problem 3 = Immediate Repair Needed Page 3 of 4
BIORETENTION MAINTENANCE INSPECTION FORM
Sketches, If Necessary:
N/A = Not Applicable 1 = Monitor for Future Repairs
N/I = Not Investigated 2 = Routine Repairs Needed
0 = Not a Problem 3 = Immediate Repair Needed Page 4of 4
RECORDING REQUESTED BY:
City of Carlsbad
Development Services Department
WHEN RECORDED MAIL TO:
City Clerk
City of Carlsbad
1200 Carlsbad Village Dr.
Carlsbad, CA. 92008
SPACE ABOVE THIS LINE FOR RECORDER'S USE
ASSESSOR'S PARCEL NO. /3 2C&—O/
PROJECT NO.
PERMANENT STORMWATER QUALITY BEST MANAGEMENT PRACTICE MAINTENANCE
AGREEMENT
DATE OF AGREEMENT:
OWNER NAME: 8ces' Rc4 Med'tc/ to J6Zg
PROJECTNAME: Bress Qc /4edc/ (&-e.cfi 1-o# i)
RESOLUTION NUMBER:
CONDITION NUMBER:
DRAWING NUMBER:
STORM WATER MANAGEMENT PLAN (SWMP) NUMBER:
This agreement is made and entered into by and between the City of Carlsbad, California, a
Municipal Corporation of the State of California, hereinafter referred to as "City"; and the Property
Owner named on the current Deed of Trust as referenced above, hereinafter referred to as
"Owner".
RECITALS
WHEREAS, Owner is proceeding to develop a property more particularly described in
Exhibit A, hereinafter referred to as "the Property"; and
WHEREAS, development of the Property has been approved, by the City, and is subject to
the requirements of the State of California Regional Water Quality Control Board-San Diego Region
Order No. ORDER NO. 2001-01/NPDES NO. CAS0108758, as promulgated within the City of
1 OF 6 Rev4117107
Carlsbad Public Works Department, Standard Urban Storm Water Mitigation Plan-Storm Water
Standards, 2003 hereinafter referred to as "storm water regulations" and incorporated herein by this
reference; and
WHEREAS, the Owner is required to comply with all Federal, State and Local storm water
regulations by employing permanent post-construction Best Management Practices (BMPs),
hereinafter referred to as "permanent BMP(s)" to ensure impacts to storm water quality are
mitigated to the maximum extent practicable (MEP) prior to being discharged from the Property;
and
WHEREAS, the City and the Owner, its successors and assigns agree that the health
safety, and welfare of the residents of Carlsbad, California, require that permanent BMP(s) be
established, constructed, inspected, and operated and maintained in perpetuity on the Property;
and
WHEREAS, the storm water regulations require that permanent BMP(s) be established,
constructed and adequately inspected, operated and maintained by the Owner, its successors and
assigns, including any homeowner or property owner association; and
WHEREAS, the Owner has caused to be prepared a Storm Water Management Plan
(SWMP) report and drawing(s) which together detail the objectives, design, construction, inspection
and operation and maintenance responsibility requirements of the permanent BMP(s)
recommended to mitigate impacts to storm water quality due to the development of the Property,
hereinafter collectively referred to as the "Storm Water BMP Plan" and incorporated herein by this
reference; and,
WHEREAS, storm water regulations require that the City ensure the continued
existence and inspection, operation and maintenance of the permanent BMP(s); and
WHEREAS, the City has required the recordation of this agreement as a condition of
approval of the project that secures the construction, inspection, operation and maintenance of on-
site permanent BMP(s) by the Owner, its successors and assigns, including any property owners
association, in perpetuity, and
NOW, THEREFORE, in consideration of the approval of this project, the foregoing
2 OF 6
promises, the mutual covenants contained herein, and the following terms and conditions,
Owner and City agrees as follows:
Owner shall comply with all the requirements of said storm water regulations and any
applicable amendments thereto, and with any other provisions of law.
The permanent BMP(s) shall be established and constructed by Owner, its successors
and assigns, in accordance with the plans and specifications identified in the Storm Water BMP
Plan and modification to the approved permanent BMP(s) shall not be made without prior approval
of the City Engineer.
Owner, its successors and assigns, including any homeowner or property owner
association, shall adequately,' inspect, operate and maintain the permanent BMP(s). This includes
all pipes and channels built to convey storm water to the facility, as well as all structures,
improvements, and vegetation provided to control the quantity and quality of the storm water runoff
and any associated practices and programs. Adequate maintenance is herein defined as good
working condition so that the permanent BMP(s) are performing in accordance with their design
objectives and functions.
Owner, its successors and assigns, shall inspect applicable permanent BMP(s) as often
as conditions require, or at frequencies recommended in the approved Storm Water BMP Plan, but
in any event at least once each year prior to the rainy season. The purpose of the inspection is to
assure continued safe and proper functioning of the facilities. The inspection shall cover the entire
facilities, berms, outlet structure, pond areas, access roads, etc. Owner shall submit an inspection
report annually to the City in a form as proscribed in the Storm Water BMP Plan or as may be
proscribed by the City. Deficiencies shall be noted in the inspection report. Any deficiencies,
repairs or maintenance obligations shall be noted in a record form and immediately remedied by the
Owner.
Owner shall maintain inspection, operation and maintenance records for at least five (5)
years. These records shall be made available to the City for inspection upon request at any time.
Owner, its successors and assigns, hereby grant permission to the City, its authorized
agents and employees, to enter upon the Property and to inspect the permanent BMP(s) whenever
3 OF 6 Rev4117/07
the City deems necessary. The purpose of inspection is to follow-up on reported deficiencies to
respond to State and Federal mandated storm water facility inspection requirements and/or to
respond to citizen complaints. The City shall provide Owner, its successors and assigns, copies of
the inspection findings and a directive.to commence with the repairs or corrective measures if
necessary.
In the event the Owner, its successors and assigns, fails to take corrective action to
maintain the permanent. BMP(s).in good working condition acceptable to the City, the City may
enter upon the Property and take whatever steps necessary to correct deficiencies identified in the
inspection report and to charge the costs of such repairs to the Owner, its successors and assigns.
This provision shall not be construed to allow the City to erect any structure of permanent nature on
the land of the Owner outside of the easement for the permanent BMP(s), if an easement is
provided, or outside the limits of the permanent BMP(s) facility footprint described on the Storm
Water BMP Plan, if an easement is not provided. It is expressly understood and agreed that the
City is under no obligation to routinely maintain or repair said facilities, and in no event shall this
Agreement be construed to impose any such obligation on the City.
Owner, its successors and assigns, will perform the work necessary to keep the
permanent BMP(s) in good working order as appropriate. In the event a maintenance schedule for
the permanent BMP(s) is outlined in the approved Storm Water BMP Plan, the schedule shall be
followed.
In the event the City pursuant to this Agreement, performs work of any nature, or
expends any funds in performance of said work for labor, use of equipment, supplies, materials,
and the like, the Owner, its successors and assigns, shall reimburse the City upon demand, within
thirty (30.) days of receipt thereof for all actual costs incurred by the City hereunder. If not paid
within the prescribed time period, the City shall secure a lien against the Property in the amount of
such costs. The actions described in this section are in addition to and not in lieu of any and all
legal remedies available to the City as a result of Owner's failure to maintain the permanent
BMP(s).
4 OF 6 Rev.4117107
10. Owner agrees that the permanent BMP(s) are privately-owned, operated and
maintained by the Owner and acceptance of the work by the City shall not contitute a responsibility
of the City to. maintain them nor a Waiver of Defects by City.
Owner agrees that all residual material that is a byproduct of the proper operation and
maintenance of permanent post-construction BMP's (waste) will be disposed of according to all
federal, state and local regulations.
The City or any officer or employee thereof shall not be liable for any injury to persons
or property occasioned by reason of the acts or omission of Owner, its agents or employees in the
performance of this agreement. Owner further agrees to protect and hold harmless City, its officials
and employees from any and all claims, demands, causes or action, liability or loss of any sort
because or arising out of acts or omissions of Owner, its agents or employees in the performance
of this agreement, including claims, demands, causes of action, liability, or loss because of or
arising out of the design or construction of the permanent post-construction BMP facilities. Said
indemnification and agreement to hold harmless shall extend to injuries to person and damages or
taking of property resulting from the design or construction of said permanent BMP(s) as provided
herein, and to adjacent property owner as a consequence of the diversion of waters from the
design, construction or maintenance of drainage systems, streets, and other improvements.
This Agreement shall be recorded against the Property and shall constitute a covenant
running with the land and shall be binding upon Owner, its successors and assigns, including any
homeowner or property owner association.
Invalidation of any one of the provisions of this Agreement shall in no way effect any
other provisions and all other provisions shall remain in full force and effect.
5 OF 6 Rov.4117/07
IN WITNESS WHEREOF, this agreement is executed by the City of Carlsbad, acting by and
through its City Manager, pursuant to Section 20.16.060 of the Carlsbad Municipal Code
authorizing such execution, and by Owner.
APPLICANT CITY OF CARLSBAD, a municipal corporation of
the State of California
ROBERT T. JOHNSON, JR., P.E.
Acting City Engineer
(Name of Owner)
By: By:
(sign here) David A. Hauser, Deputy City Engineer
RCE 33081 Exp. 06/30/2008
print name here)
(title and organization of signatory)
By:
(sign here)
(print name here)
(title and organization of signatory)
(Proper notarial acknowledgment of execution by OWNER must be attached)
(Chairman, president or vice-president and secretary, assistant secretary, CFO or assistant
treasurer must sign for corporations. Otherwise, the corporation must attach a resolution certified
by the secretary or assistant secretary under corporate seal empowering the officer(s) signing to
bind the corporation.)
APPROVED AS TO FORM:
RONALD R. BALL
City Attorney
In
Deputy City Attorney
6 OF 6 Re'.4117107
EXHIBIT 'A'
Lot 1 of Carlsbad Tract CT 02-15 Bressi Ranch in the City of Carlsbad, County of San
Diego, State of California, According to Map Thereof, No. 14960 Filed in the Office
of the County Recorder of San Diego County, February 4, 2005.
1 OF 1 Rev4?17/07
c)94 ROAD
VALOMAR
ROSE r-'
1/ POINSETTIA
\' LANE
t ELFUERTE
STREET
PROJECT 'SITE
1cINrrY MAP
NOT TO SCALE'