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HomeMy WebLinkAboutSUP 06-11; ROBERTSON RANCH PARK; PRELIMINARY STORM WATER MANAGEMENT PLAN FOR ROBERTSON RANCH, PA 12 & 13; 2006-05-01PRELIMINARY STORM WATER MANAGEMENT PLAN For ROBERTSON RANCH, PA 12 & 13 WEST VILLAGE SUP 06-11 Prepared: May 1, 2006 Revised: February 23, 2007 Revised: April 9, 2007 J.N. 06-1172/5 Prepared By: O'DAY CONSULTANTS, INC. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010-6609 (760) 931-7700 Keith W. Hansen, RCE 60223,Exp. 6/30/08 Date 0 PRELIMINARY STORM WATER MANAGEMENT PLAN For ROBERTSON RANCH, PA 12 & 13 WEST VILLAGE SUP 06-11 Prepared: May 1, 2006 Revised: February 23, 2007 Revised: April 9, 2007 J.N. 06-1172/5 Prepared By: O'DAY CONSULTANTS, INC. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010-6609 (760) 931-7700 Exp. 6/30/08 OF Keit6 W. Hansen, RCE 60223, Exp. 6/30/08 TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION......................................................................................2 1.1 Hydrologic Unit Contribution............................................................................2 1.2 Beneficial Uses ..................................................................................................3 2.0 CHARACTERIZATION OF PROJECT RUNOFF................................................4 2.1 Soil Characteristics ............................................................................................4 2.2 Potential Discharges...........................................................................................4 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY........................5 3.1 Site Design BMPs ............................................................................................... 5 3.2 Source Control BMPs........................................................................................5 33 Individual Priority Project Categories ...............................................................5 3.4 Treatment Control BMPs...................................................................................5 3.5 Construction BMPs............................................................................................6 4.0 MONITORING, INSPECTION, AND REPORTING............................................6 Attachments: Vicinity map Soils Group Map 3; San Diego Region Hydrologic Boundary Map Beneficial uses for the hydrologic unit 303(D) list for impaired water bodies Table 2: Anticipated and potential pollutants Tablel: Storm Water BMP Requirements Matrix Project site plan & BMP map Site Design BMPs Source Control BMPs Treatment Control BMPs Excerpt from "City of Carlsbad Dry Weather Field Screening and Analytical Monitoring Program" dated 2003 Storm Water Requirements Applicability Checklist 1 GAO 11014\PSWMP\PAI2&13_PSWMPO2.doc STORM WATER MANAGEMENT PLAN Federal, state and local agencies have established goals and objectives for storm water quality in the region. The proposed project, prior to the start of construction activities, will comply with all federal, state and local permits including the Stormwater Management Plan (SWMP) required under the County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance (WPO) (section 67.87 1), the City of Carlsbad's Standard Urban Storm Water Mitigation Plan, and the National Pollution Discharge Elimination System (NPDES) from the Regional Water Quality Control Board (RWQCB). The purpose of this SWMP is to address the water quality impacts from the proposed improvements as shown on the Tentative Map. This project will provide guidelines in developing and implementing Best Management Practices (BMPs) for storm water quality during construction and post construction. Since the site is more than 1 acre, a Storm Water Pollution Prevention Plan (SWPPP) will be required. A SWPPP will be prepared and approved prior to issuance of a grading permit. The approved SWPPP shall be implemented during the construction phase. The SWPPP will consist of the selected BMPs, guidelines, and activities to carry out actions, which will prevent the pollution of storm water runoff. The SWPPP will also include the monitoring and maintenance of the construction BMPs during the construction phase. C 1.0 PROJECT DESCRIPTION The project is located within Parcel 2 of Lot Line Adjustment ADJ 01-03, per the Certificate of Compliance recorded on November 28, 2001 as file 2001-0865065 of official records of San Diego County, California. The Robertson Ranch PA 12-13 consists of approximately 20.9 acres that will be developed in mass graded pads for future park and school sites (See Attachment 8). PA 12-13 is bounded by the Robertson Ranch East Village to the north, Cannon Road to the east, El Camino Real to the south and a proposed habitat corridor to the west. This project has been determined to be a high priority construction project and is subject to the "Priority Project Permanent Storm Water BMP Requirements" and "Standard Permanent Storm Water BMP Requirements" as outlined in the City's SUSMP, as well as "Construction Storm Water BMP Performance Standards." See the Storm Water Requirements Applicability Checklist (Attachment 12). 1.1 Hydrologic Unit Contribution The project is located in the Los Monos Hydrologic Subarea (904.31) of the Agua Hedionda Watershed in the Carlsbad Hydrologic Unit in the San Diego Region (Attachment 3). Under both existing and proposed conditions, storm runoff from PA 12-13 flows into existing onsite naturally vegetated drainage courses and is then conveyed under El Camino Real where flows confluence with the Agua Hedionda Creek, flow then continues westerly to Agua Hedionda Lagoon. The proposed project will not alter the drainage patterns on site. Drainage infrastructure - - downstream designed to handle post-development storm runoff from the West Village. 2 G:\O1 I014WSWMP\PAI2&132SWMP02.doc 1.2 Beneficial Uses The beneficial uses for the hydrologic unit are included in attachment 3, and the definitions are listed below. This information comes from the Water Quality Control Plan for the San Diego Basin. MUN - Municipal and Domestic Supply: Includes uses 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. IND - Industrial Service Supply: 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 repressurization. REC 1 —Contract 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. REC 2 —Non-Contact Recreation: Includes the uses of water for recreational activities involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These 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. COMM - Commercial and Sport Fishing: 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. 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. EST - Estuarine Habitat: Includes the uses of water that support estuarine ecosystems including, but not limited to, preservation or enhancement of estuarine habitats, vegetation, fish, or wildlife (e.g., estuarine mammals, waterfowl, shorebirds). MAR —Marine Habitat: Includes uses of water that support marine ecosystems including, but not limited to, preservation or enhancement or marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mammals, shorebirds). 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 food and sources. RARE - Rare, Threatened, or Endangered Species: 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. AQUA - Aquaculture: Includes the use 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. 3 GAO 1 1014\PSWMP\PAI2& 13_PSWMPO2.doc MIGR —Migration of Aquatic Organisms: 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. SHELL - Shellfish Harvesting: Includes uses of water that support habitats suitable or the collection of filter-feeding shellfish (e.g., clams, oysters, and mussels) for human consumption, commercial, or sport purposes. 2.0 CHARACTERIZATION OF PROJECT RUNOFF According to the California 1998 303d list published by the RWQCB (attachment 5), Agua Hedionda Lagoon is an impaired water body associated with the direct stormwater discharge from this project. Agua Hedionda Lagoon has low priority impairment for high coliform count and medium priority impairment for sedimentation and siltation. Sites tributary to clean water act section 303(D) water bodies require additional BMP implementation. The proposed drainage is shown in the Drainage Study for PA 12-13 West Village by O'Day Consultants dated February 23, 2007. The total disturbed area for this project is 22.46 acres. PA 12's peak runoff for the 100-year storm event is 15.5 CFS with an area of 13.41 acres. PA 13's peak runoff for the 100-year storm event is 8.6 CFS with an area of 6.62acres. Desilting basin calculations are also included in the drainage study mentioned above. Runoff from this project is combined with runoff from the larger Agua Hedionda watershed before leaving the site through the 8'x8' RCB under El Camino Real. Refer to the February 20, 2006 study titled, Hydrologic and Hydraulic Analyses for Robertson's Ranch prepared by Wayne Chang for pre- and post- developed conditions. 2.1 Soil Characteristics A soils report for the site has been prepared by GeoSoils, Inc. titled Preliminary Geotechnical Evaluation - Planning Area 12, 13.44 acres and Planning Area 13, 692 acres, Robertson Ranch West, Carlsbad, San Diego County, California 92010 dated January 31, 2007. The project area consists of soils groups A, B, C, and D, with the majority of soil being group D. See soils group map, see Attachment 2. 2.2 Potential Discharges The project will contain some pollutants commonly found on similar developments that could affect water quality. The following list is taken from Table 2 of the City of Carlsbad's Storm Water Standards Manual (Attachment 6). It includes anticipated pollutants for mass graded lots and slopes. Low priority sediment discharge (Agua Hedionda Lagoon Impairment) Low priority bacteria indicators (Agua Hedionda Lagoon Impairment) 4 110 1014\PSWMP\PAL2&13_PSWMPO2.doc C- 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY To address water quality for the project, BMPs will be implemented during construction and post construction. Required BMPs are selected from Table 1: Storm Water BMP requirements Matrix, of the City of Carlsbad's Storm Water Standards Manual (Attachment 7). 3.1 Site Design BMPs Control of post-development peak storm water runoff discharge rates and velocities is desirable in order to maintain or reduce pre-development downstream erosion by applying the following concepts (See attachment 9 for details): Conserve Natural Areas: The natural drainage channel dividing the east and west village will be left in a natural, undisturbed condition. Protect Slopes and Channels:. All runoff will be safely conveyed away from the tops of slopes. Energy dissipaters shall be installed at the outlets of new storm drains, culverts, or channels that enter unlined channels in accordance with applicable standards and specifications to minimize erosion. Energy dissipaters will be installed in such a way as to minimize impacts on receiving waters. 3.2 Source Control BMPs Source Control BMPs help minimize the introduction of pollutants into storm water in order to maintain or reduce pre-development levels of pollutants by applying the concepts in Attachment 10. 3.3 Individual Priority Project Categories Hillside Landscaping Hillside areas disturbed by project development shall be landscaped with deep-rooted, thought tolerant plant species selected for erosion control, in accordance with the Carlsbad Landscape Manual. 3.4 Treatment Control BMPs As identified in Table 1, a combination of treatment control BMPs shall be incorporated into the project. The project has been designed so that runoff is treated by Site Design BMPs prior to Structural Treatment BMPs. Structural Treatment BMPs were selected by comparing the list of expected pollutants to the removal efficiencies of various treatment BMPs. Special considerations were given to the pollutants for which Agua Hedionda is considered impaired and for the analytes, which have been found to exceed objectives. Treatment BMPs selected to treat these pollutants are: ( 1. Desilting Basins 5 G:\01 1014\PSWMPPA12&13_PSWMP02.doc 2. Drainage Courses and S wales The combination of these BMPs maximizes pollutant removal efficiency for the particular pollutants of concern to the maximum extent practicable. Sizing of the desilting basins can be found in the Drainage Study for Robertson Ranch Habitat Corridor Grading by O'Day Consultants dated February 21, 2007. 3.5 Construction BMPs The following is a list of potential construction phase BMPs to be used. Silt fence, fiber rolls, or gravel bag berms Check dams Street sweeping and vacuuming Storm drain inlet protection Stabilized construction entrance/exit Vehicle and equipment maintenance, cleaning, and fueling Hydroseed, soil binders, or straw mulch Material delivery and storage Stockpile management Spill prevention and control Waste management for solid, liquid, hazardous and sanitary waste, contaminated soil. Concrete waste management A SWPPP will be prepared and approved prior to issuance of a grading permit. Construction BMPs for this project will be selected, constructed, and maintained through the SWPPP to comply with all applicable ordinances and guidance documents. The approved SWPPP shall be implemented during the construction phase. 4.0 MONITORING, INSPECTION, AND REPORTING During construction, the BMPs will be monitored on a weekly basis, and observations recorded on the included checklists (See next page). The Owner and Developer will be responsible for the monitoring and maintenance of the BMPs. G:\01 1014\PSWMP\PAI2&I 3_PSWMPO2.doc BMP CHECKLIST (TO BE COMPLETED WEEKLY) DATE WEATHER INADEOUATE BMPs CORRECTIVE ACTION OBSERVATIONS 110 1014\PSWMP\BMP CHECKLIST.doc SITE C/fl' OF OCEANSIDE HIGHWAY-j,,78 VILL. r NOT TO SCALE C/fl' OF LISTA \ ROAD mw b CAF/USBAD Cos AVE PACIFIC OCEAN CITY OF ENCIM IA S VICINITY MAP NO SCALE CITY OF SAN MARCOS b> ou/f{ /5 ,j/m2uEN\9 + C D flT T t çj I A C \ \ \ ,.\NU.AYZ!.. A G '• J7 LI \\ALSBAD Po t \\\ \\ \\\,J '.• - - }j r . \ D afa f I 902.80 Aguanga HA 2.81 Vail NSA 2.82 Devils Hole NSA 2.83 Redec NSA 284 lute Creek NSA 902.90 0akgrove HA 2.91 Lower Culp NSA 2.92 Previtt Canyon HSA 2.93 Dodge NSA 2494 Chihuahua NSA 903400 SAN LUIS REV HYDROLOGIC UNIT 903.10 Lower San Luis HA 3.11 Mission NSA 3.12 Bonsall NSA 3.13 Moosa HSA 3.14 Valley Center NSA 3.15 Woods HSA 3.16 Rincon NSA 903.20 Monserate HA 3.21 Pala NSA 3,22 Pauma NSA 3.23 La Jolla Amago HSA 903.30. Warner Valley HA 3.31 Warner HSA 3.32 Combs NSA 904.00 CARLSBAD HYDROLOGIC UNIT 904.10 Loma Alta HA 904.20 Buena Vista Creek HA 4.21 El Salto HSA 4.22 Vista NSA 904.30 Agua Hedionda.kl&, 4.32 Buena NSA 904.40 Encinas HA 904.50 San Marcos HA 4.51 Batiquitos NSA 4.52 Richland NSA 4.53 Twin Oaks NSA 904.60 Escondido Creek HA 4.61 San Elijo HSA 4.62 Escondido NSA 4.63 Lake Wohiford HSA 905.00 SAN DIEGUITO HYDROLOGIC UNIT 905.10 Solana Beach HA 5.11 Rancho Santa Fe NSA 512 La Jolla NSA 906.20 Hodges HA 521 Del Dios HSA 5.22 Green NSA 5.23 leUcita NSA 5.24 Bear NSA 905.30 San Pasqual HA 5.31 Highland NSA 5.32 Las Lomas Muertas HSA 5.33 Reed NSA 5.34 Hidden NSA 535 Guojito HSA 5.36 Vineyard NSA 905.40 Santa Maria Valley HA 5.41 Ramona HSA 5.42 Lower Hatfield NSA 5.43 Wash Hollow HSA 5.44 Upper Hatfield NSA 5.45 Baltena NSA 5.46 East Santa Teresa NSA 5.47 West Santa Teresa NSA 905.50 Santa Ysabel HA 5.51 Boden NSA 552 PamoH9A 553 Sutherland NSA 5.54 Witch Creek NSA 906.00 PENASQU1TOS HYDROLOGIC UNIT 906.10 Miramar Reservoir HA 906.20 Poway HA 906.30 Scripps HA 906.40 Miramar HA 906.50 Tecotote HA 907.00 SAN DIEGO HYDROLOGIC UNIT 907.10 Lower San Diego HA 7.11 Mission San Diego NSA 7.12 Santee HSA 713 El Cajon HSA 7.14 Caches HSA 7.15 El Monte HSA 907.20 San Vicente HA 7,21 Fernbrook NSA 7.22 Kimball HSA 7.23 Gower NSA 7.24 Barona NSA 907.30 El Capitan HA 7.31 Conejos Creek HSA 732 Glen Oaks NSA 7.33 Alpine NSA 907.40 Boulder Creek HA 741 inaja NSA 7.42 Spencer NSA 743 Cuyamaca NSA - - 4OLYMPUS\ ). I T0URMAL1F1E UEt1I IicTT EN D Regional Boundary Hydrologic Unit Boundary (HU) Hydrologic Area Boundary (HA) Hydrologic Subarea Boundary (SA) ) i I t3;.ite 11.82 Canyon City NSA 11.83 Clover Flat NSA 11.84 Hill NSA 11.85 Hipass NSA NOTE: The names and areas shown on this map are the same as used by the Department of Water Resources (DWR) In their Bulletin 130 Series. The numbering system used on this map Is an adoption of the numbering system used in the 130 Series, The 1980 updated names and boundaries shown on the map are In accordance with an agreement with DWR and US Geological Sutvey. The 1096 revision of this snap Includes newly recognized hydrologic suuareav within the MIssion Viejo HA (90.20). Notes I & 3 do not apply to these subareas. Solana KEY TO REGION (/d 4 87 U 11111 April 1973 Revised: July 1976 Revised: August 1986 Stczte Wafer Reurces Contr1Board Surveillance and Monitoring Section T.E.Lavendo,P.E, 1 - ______________ 1_-___.- -- Revised; April 1995 Regional Water Quality Cotro1 Boord' San Diego Region Water Qàallty Standards. Unit D.F. I{oirup Jr. State of California SAN DIE REA (SD;Lookoul US NA RESERAT FOR NAT 6 CABRILLO NAT REGIONAL WATER QUALITY CONTROL BOARD San Diego RIZ;gi on (9) 0 HYDROLOGIC BASIN PLANNING A Scale 1:250,000 0 5 tO 15 20 Miles - Ii WTI - -. U Table 2-2. BENEFICIAL USES OF. INLAND SURFACE WATERS 1,2 InlandSurfaceWaters. - Hydrologic Unit IflN&N BENEFICIAL USE M U A G R. I N D' P R C G WR R F — — — — — — — — SC II 1 JWO R E R E 2 — CØR B I L W A M — C 0 L 0 — W LIRW DIE 1 S P N anDiego County Coastal 8treainl -conUnuid Buena Vista Lagoon 421 - - - - See Coastal Whigs- Table 2-3 •. Buena Vista creek 4• Buena Vista Creek . .+ . S 421 + • • . I.!.1 Agua Hedlonda 4.31 See Coastal Waters- Table 2-3 AguaHediondaCreek 4.32 . S S Buena Creak 432 f . Ague Hedionda Creek 4.31 . . S LeltarboxCanyon 4:31 • - - - • - - • - - Canyon delasEndnas 440 + San Marcos Creek Watershed Batiqultos Lagoon 4.51 = = = SeeCoast- Te - - - SanMarcosCreek 4.52 + . . unnamed IflterTflItteflt streams 453 + . • • San Marcos Creek Watsrehod Sian Marcos Creek 451 •+ S . EncinitasCreek 4.51 1 + 1 — — 1 — 1 — 1 — — 1•1 — • — — — — — — Existing Beneficial Use üte multipta tnss if they cross hydrologic ama or sub area boundaries. 0 Potential Beneficial Use 2 Swakfal we dos%radons apply to all tbularin to the Indicated aociy, it not listed aeparatety. + Excepted From MUN (See Text) -2 Marc 7 bb 4L USES Table 2-3 BENEFICIAL USES OF COASTAL WATERS Coastal Waters Hydrologic Unit Basin BENEFICIAL USE I N DV N A R E CC H E 2 C .0 MO M I Nb Gumer B I L. E S T W I L D R A RH E M A A Q U A MMPA R L = Pacific Ocean ...... Dana Point Harbor ••• •• • Del Mar Boat Basin • • • • • - - • • . . Mission Bay 01010 010- 0 Oceanside Harbor tan Diego Bay . 1 010 Coastal Lagoons Tijuana River Estuary liii - • • • • • • • • 01 0 - Mouth of. San Diego River 7.11 • • S • S • • • • Los Penasqultos Lagoon 2 8.10 - • • • • • • • - • • - San DieguitoLagoon 5.11 • I S • • I • S 5 Satiqultos.Lagoon 4.51 5 S S • I S • 01 5 San Elijo Lagoon 5.61 0. I S • I S I • I Aqua Hedionda Lagoon 4.31 • • • • S • • • • S S Includes the tidal prisms of the Otay and Sweetwater Rivera. 2 Fishing from shore or boat permitted, but other water contact recreational (REC-1) uses are prohibited. S Existing Beneficial Use Table 2-3 BFP4FPICIAL USES March 12, 1997 - 4.. /7 2002 CWA SECTION 303(d) L I S T O F W A I t R QUALITY LIMITED SEGMENT Approved &vLP4: J1111. 200.1 SAN DIEGO REGIONAL WATER QUALiTY CONTROL B O A R D 9 R Ague Bedionda Creek 90431000 Total Dissolved Solids LOW 7 Miles Urban Runo8torm Sewers Unknown NenpoInt Source Unknown point source . ---- 9 B Agua Hedionda Lagoon 90431000 Bacteria Indicator, Low 68 Acres Nonpolut/Polut Source SedanWIonIltadon Low 6.8 Acres Nooluoiat Source 9 R Ailso Creek 90113000 - Baderis Indicators MedIum 19 MIles Urban RanofflStarso Sewers Unknown point source Nonpolnt!Polat Source Phosphorus Low 19 Miles bpabma located at lower 4 miles. Urban RnnoWSthrm Sewers Unknown Noupotnt Source Unknown point source Tozidly . Low 19 mugs Urban Rime WSterm Sewers Unknown Nonpoint Source Unknown point source -_ -...---".--.'-----*-.- ---- 9 £ Aliso Creek (mouth) 90113000 BarIa IndIrqon, Medium 0.29 Acres - NoepolntlPotut Source .... ....... -_--__,.. 9 B Buena Vista Lagoon 90421000 Low 202 Acres NonpolntlPolnt Source Nutrients Low 202 Acres &tthtatedsfte of biçab7nmt u 150 acres located in upper portion oflagoon NoupotntlPolot Source Sed&mentatloniltatIon Medium 202 Acres Noupoint/Point Source 1 of . tomi Water Standards ..,O3IO3 A1*M IM . . :. - .:': :•-.. When referred to this Section, by Step 2 of Section II, complete the analysis required for your project In the subsections of Section 111.1 below. . 1. IDENTIFY POLLUTANTS & CONDITIONS OF CONCERN A. Identify Pollutants from the Project Area Using Table 1, identify the projects anticipated pollutants. Pollutants associated with any hazardous material sites that have been remedlated or are not threatened by the proposed project are not considered a pollutant of concern. Projects meeting the definition of more than one project category shall identify all general pollutant categorfesthat apply. Tahlog AnfiiIritniI 2n11 PntanIII PnII. slants narfnd liv lnl ll Tunin General Pollutant Trash Oxen Bacteria Heavy organic & Demanding 01 81 & Sediments Nutrients Metals Compounds Debris &sbstances Grease Viruses PestIcides 'Detached Residential X X X X X X x. Development Attached Residential X X X Pt') PM P11) X Commercial Oevabpméd P11) Pt') PP) X Pt') X P13) PM >10m.00)I 2 Automotive R X )04N • Restaurants X X X X HIll&d. Development X X X X X x >5,GW ft2 Parking Lots P(') PC1) X X P(') X P(') Streets, Highways & X p(1)X x X() X Pt') X Freeways X anticipated potential pollutant if landscaping exists on-site. rs potential pollutant If the project includes uncovered parking areas. A potential pollutant If land use involves food or animal waste products. 1 (3) Including petroleum hydrocarbons. Including solvents. 3torm Water Standards 4/03/03 Table 1. Standard Development Project & Priority Project Storm Water BMP Requirements Matrix. BMPs Applicable to Individual doilty Project CategodesPJ 06 CO CL I I éi i I Jr 1 .1U. 1 Site scums Treshnent Design BMPsI1BMPSI Conbcl td . .o . . . Con bol BMPst4 StandardProjscts R R 00 00000000 0 Priority Projects: Detached Residential Development R R R R R S Attached Resklenfal R R R $ 0-a— mmardal Development R R • R R R R S J000 IF AUtOmOtive Repair Shop R R R R R R R S Restaurants R R R R S HlilskteD8veiopnient R R R R S >5,000 ft2 PaddngLots R R R(4 S Streets, Highways & R R Freeways R = Required; select one or more applicable and appropriate BMPa from the applicable steps In Section 1I1.2.A4), or equivalent as Identified In Appendix C. 0 = Optionall or may be required by City staff. As appropriate, applicants are encouraged to incorporate treatment control BMPs and BMPs applicable to Individual pdärity project categories Into the project design.. City staff may require one or more these BMPe, where appropriate. S = Select one or more applicable and appropriate treatment control BMPa from Appendix C. Refer to Section IlI.2.A. Refer to Section 111.2.9. Pdority project categories must apply specific storm water BMP requirerridift where applicable. Priority projects are subject to the requirements of all priority project categories that apply. Refer to Section U.N. Applies If the paved area totals >5,000 square feet or with >15 parking spaces and Is potentially exposed to urban runoff. 0 MIL11, (V 0' 200' 100' 400' / SCALE: 1" = 200' -- p 1 V A : SHEET 1 OF 1 SHEET LL'?GENJ) SITE BOUNDARY PLANNING AREA BOUNDARIES BASIN BOUNDARY NA IlIRALL V kEGETA 10 DRAINAGE COURSE f4°&V &°A CE PERMANENT DESIL TA liON BASIN RIP RAP SUMMARY S#MP ROBERTSON RANCH PA 12 & 13 ©2006 O'Day Consultants, Inc. 0 DESIGNED BY: S.K. DRAWN BY: B.B. DATE: MAY 2006 SCALE: AS SHOWN PROJECT MGR.: K.H. T AeorN T S JOB NO.: 01-1014 CONSUL 2710 Loker Avenue West Suite 100 Civil Engineering Planning ENGINEER OF WORK Carlsbad, California 92010 Processing 760-931-7700 Fax: 760-931-8680 Surveying DATE: KEITH HANSEN RCE: 60223 Oday©odayconsultants.com G:\011014\0114SWMP—Q.dw Oct 31, 2006 3:30pm Xrefs: 0114map; 01148GRD; 0114TP—Q; 0114TPCH; 9820tp03—a; 0114BMAP; 011472; 0114qgrd; 0114QHYD02 Section 3 - Site and Facility Design for Water Quality Protection 3.1 Introduction Site and facility design for stormwater quality protection employs a multi-level strategy. The strategy consists of: i) reducing or eliminating post-project runoff 2) controlling sources of Pollutants; and 3), if still needed after deploying 1) and 2), treating contaminated stormwater runoff before discharging it to the storm drain system or to receiving waters. This section describes how elements 1), 2), and 3) of the strategy can be incorporated into the site and facility planning and design process, and by doing so, eliminating or reducing the amount of stormwater runoff that may require treatment at the point where stormwater runoff ultimately leaves the site. Elements i) and 2) may be referred to as "source controls" because they emphasize reducing or eliminating pollutants in stormwater runoff at their source through runoff reduction and by keeping pollutants and stormwater segregated. Section 4 provides detailed descriptions of the BMPs related to elements i) and 2) of the strategy. Element 3) of the strategy is referred to as "treatment control" because it utilizes treatment mechanisms to remove pollutants that have entered stormwater runoff. Section 5 provides detailed descriptions of BMPs related to element 3) of the strategy. Treatment controls integrated into and throughout the site usually provide enhanced benefits over the same or similar controls deployed only at the "end of the pipe" where runoff leaves the project site. 3.2 Integration of BMPs into Common Site Features Many common site features can achieve stormwater management goals by incorporating one or more basic elements, either alone or in combination, depending on site and other conditions. The basic elements include infiltration, retention/detention, bioffiters, and structural controls. This section first describes these basic elements, and then describes how these elements can be incorporated into common site features. Infiltration Infiltration is the process where water enters the ground and moves downward through the unsaturated soil zone. Infiltration is ideal for management and conservation of runoff because it filters pollutants through ( the soil and restores natural flows to groundwater and downstream water bodies. See Figure 3-1. Figure 3-1 Infiltration Basin January 2003 California Stormwater BMP Handbook Se"fl 3 SA I Facility Design for Water Quality Protection The infiltration approach to stormwater management seeks to "preserve and restore the hydrologic cycle." An infiltration stormwater system seeks to infiltrate runoff into the soil by allowing it to flow slowly over permeable surfaces. The slow flow of runoff allows pollutants to settle into the soil where they are naturally mitigated. The reduced volume of runoff that remains takes a long time to reach the outfall, and when it empties into a natural water body or storm sewer, its pollutant load is greatly reduced. infiltration basins can be either open or closed. Open infiltration basins, include ponds, swales and other landscape features, are usually vegetated to maintain the porosity of the soil structure and to reduce erosion. Closed infiltration basins can be constructed under the land surface with open graded crushed stone, leaving the surface to be used for parking or other uses. Subsurface closed basins are generally more difficult to maintain and more expensive than open filtration systems, and are used primarily where high land costs demand that the land surface be reclaimed for economic use. Infiltration systems are often designed to capture the "first flush" storm event and used in combination with a detention basin to control peak hydraulic flows. They effectively remove suspended solids, particulates, bacteria, organics and soluble metals and nutrients through the vehicle of filtration absorption and microbial decomposition. Groundwater contamination sh e considered as a potential adverse effect and should be considered where shallow - rater is source of drinking water. In cases where groundwater sources are deep, there '- ery low chance of contamination from normal concentrations of typical urban runoff. Retention and Detention Retention and detention systems differ from infiltration systems primarily in intent. Detention systems are designed to capture and retain runoff temporarily and release it to receiving waters at predevelopment flow rates. Permanent pools of water are not held between storm events. Pollutants settle out and are removed from the water column through physical processes. See Figure 3-2. Retention systems capture runoff and retain it between storms as shown in Figure 3-3. Water held in the system is displaced by the next significant rainfall event. Pollutants settle out and are thereby removed from the water column. Because the water remains in the system for a period of time, retention systems benefit from biological and biochemical removal mechanisms provided by aquatic plants and microorganisms. See Figure 3-3. "ftfff 'do41Dw Figure 3-2 Simple Detention System Section 3 Site and Facility Design for Water Quality Protection -. Retention/detention systems may release runoff slowly enough to reduce down stream peak flows e?4 uugrpzGs, tdsW to their pre-development levels, allow fine sediments to settle, and uptake dissolved -N-1d*kAM nutrients in the runoff where wetland vegetation is included. Bioretention facilities have the added benefit of aesthetic appeal. These systems can be placed in parking lot islands, landscaped area surrounding buildings, perimeter parking lots and other open space sections. Placing bioretention facilities on Awhy land that city regulations require developers to devote to open space efficiently uses the land. An experienced landscape architect can choose plant Figure 3-3 speces and planting materials that are easy to Retention System maintain, aesthetically pleasing, and capable of effectively reducing pollutants in runoff from the site. Constructed wetland systems retain and release stormwater in a manner that is similar to retention or detention basins. The design mimics natural ecological functions and uses wetland vegetation to filter pollutants. The system needs a permanent water source to function properly and must be engineered to remove coarse sediment, especially construction related sediments, from entering the pond. Stormwater has the potential to negatively affect natural wetland functions and constructed wetlands can be used to buffer sensitive resources. Bioffiters Biofilters, also known as vegetated swales and filter strips, are vegetated slopes and channels designed and maintained to transport shallow depths of runoff slowly over vegetation. Biofilters are effective if flows are slow and depths are shallow (3% slope max.). The slow movement of runoff through the vegetation provides an opportunity for sediments and particulates to be filtered and degraded through biological activity. In most soils, the biofUter also provides an opportunity for stormwater infiltration, which further removes pollutants and reduces runoff volumes. See Figure 3-4. d&dOpe v,WaSirn. tolsnusspsviodfr J,,nundatl&u, Figure 3-4 Vegetated Swab Swales intercept both sheet and concentrated flows and convey these flows in a concentrated, vegetation-lined channel. Grass filter strips intercept sheet runoff from the impervious network of streets, parking lots and rooftops and divert stormwaters to a uniformly graded meadow, buffer zone, or small forest. Typically the vegetated swale and grass strip planting palette can January 2003 CalifornIa Stormwater BMP Handhnnk Section 3 S d Facility Design for Water Quality Protection comprise a wide range of possibilities from dense vegetation to turf grass. Grass strips and vegetated swales can function as pretreatment systems for water entering bioretention systems or other BMPs. If biofilters are to succeed in filtering pollutants from the water column, the planting design must consider the hydrology, soils, and maintenance requirements of the site. Appropriate plantings not only improve water quality, they provide habitat and aesthetic benefits. Selected plant materials must be able to adapt to variable moisture regimes. Turf grass is acceptable if it can be watered in the dry season, and if it is not inundated for long periods. Species such as willows, dogwoods, sedge, rush, lilies and bulrush species tolerate varying degrees of soil moisture and can provide an attractive plant palette year round. Structural Controls Structural controls in the context of this section include a range of measures that prevent pollutants from coming into contact with stormwater. In this context, these measures may be referred to as "structural source controls" meaning that they utilize structural features to prevent pollutant sources and stormwater from coming into contact with one another, thus reducing the opportunity for stormwater to become contaminated. Examples of structural source controls include covers, impermeable surfaces, secondary containment facilities, runoff diversion berms, and diversions to wastewater treatment plants. (Si Streets 1ore than any other single element, Street design has a powerful impact on stormwater quality. Street and other transportation related structures typically can comprise between 6o and 70% of the total impervious coverage in urban areas and, unlike rooftops, streets are almost always directly connected to an underground stormwater system. Recognizing that Street design can be the greatest factor in development's impact on stormwater quality, it is important that designers, municipalities and developers employ street standards that reduce impervious land coverage. Directing runoff to bioffiters or swales rather than underground storm drains produces a street system that conveys stormwater efficiently while providing both water quality and aesthetic benefits. On streets where a more urban character is desired, or where a rigid pavement edge is required, curb and gutter systems can be designed to empty into drainage swales. These swales can run parallel to the street, in the parkway between the curb and the sidewalk, or can intersect the street at cross angles, and run between residences, depending on topography or site planning. Runoff travels along the gutter, but instead of being emptied into a catch basin and underground pipe, multiple openings in the curb direct runoff into surface swales or infiltration/detention basins. In recent years new street standards have been gaining acceptance that meets the access re ments of local residential streets while reducing impervious land coverage. These ds create a new class of street that is narrower and more interconnected than the current '.i street standard, called an "access" street. An access street is at the lowest end of the Street hierarchy and is intended only to provide access to a limited number of residences. 3-4 California Stormwater BMP Handbook Section 3 Site and Facility Design for Wafer Quality Protection Street design is usually mandated by local municipal standards. Officials must consider the scale of the land use as they select stormwater and water quality design solutions. Traffic volume and speeds, bicycle lane design criteria, and residential and business densities influence the willingness of decision makers to permit the narrow streets that include curbless design alternatives. Emergency service providers often raise objections to reduced street widths. Street designs illustrated here meet national Fire Code standards for emergency access. An interconnected grid system of narrow streets also allows emergency service providers with multiple access routes to compensate for the unlikely possibility that a street maybe blocked. Many municipal street standards mandate 80 to 100% impervious land coverage in the public right-of-way, and are a principal contributor to the environmental degradation caused by development. A street standard that allows an interconnected system of narrow access streets for residential neighborhoods has the potential to achieve several complimentary environmental and social benefits. A hierarchy of streets sized according to average daily traffic volumes yields a wide variety of benefits: improved safety from lower speeds and volumes, improved aesthetics from reet trees and green parkways, reduced impervious land coverage, less heat island effect and ( wer development costs. If the reduction in street width is accompanied by a drainage system - that allows for infiltration of runoff, the impact of streets on stormwater quality can be greatly mitigated. There are many examples of narrow streets, from both newly constructed and older communities, which demonstrate the impact of street design on neighborhood character and environmental quality. See Table 3-1. Table 3-1 Adopted Narrow Street Standards (Typ. Cross-Sections,, two-way traffic) City of Santa Rosa 30 ft wide with parking permitted both sides, <woo Average Daily TraffiAD1 26-28 ft with parking permitted one side 2Oft-no parking permitted 2o ft neck downs at intersections City of Palmdale 28 ft wide with parking permitted both sides City of San Jose 30 ft wide with parking permitted both sides, <21 Dwelling Units (DU) 34 ft wide with parking permitted both sides, <121 DU City of Novato 24 ft wide with parking permitted both sides, 2-4 DU 28 ft with parking permitted both sides, 5-15 DU ounty of San Mateo 19 ft wide rural pavement cross-section with parking permitted on adjacent gravel shoulders A comparison of street cross-sections is shown in Figure 3-5. ige I. S /t d Facility Design for Water Quality Protection Figure 3-5 Comparison of Street Cross-Sections (two-way traffic, residential access streets) 3.2.2 Parking Lots In any development, storage space for stationary vehicles can consume many acres of land area, often greater than the area covered by streets or rooftops. In a neighborhood of single-family homes, this parking area is generally located on private driveways or along the street. In higher density residential developments, parking is often consolidated in parking lots. ace for storage of the automobile, the standard parking stall, occupies only 160 ft2, but —u combined with aisles, driveways, curbs, overhang space, and median islands, a parking lot can require up to 400 ft2 per vehicle, or nearly one acre per 100 cars. Since parking is usually accommodated on an asphalt or concrete surface with conventional underground storm drain systems, parking lots typically generate a great deal of DCIA. Section 3 Site and Facility Design for Water Quality Protection There are many ways to both reduce the impervious land coverage of parking areas and to filter runoff before it reaches the storin drain system. Hybrid Parking Lot Hybrid lots work on the principle that pavement use differs between aisles and stalls. Aisles must be designed for speeds between 10 and 20 mph, and durable enough to support the concentrated traffic of all vehicles using the lot. The stalls, on the other hand, need only be designed for the 20r 3 mph speed of vehicles maneuvering into place. Most of the time the stalls are in use, vehicles are stationary. Hybrid lots reduce impervious surface coverage in parking areas by differentiating the paving between aisles and stalls, and combining impervious aisles with ,ermeable stalls, as shown in Figure 3-6. Imperviôw aids enneab1e stalls Figure 3-6 Hybrid Parking Lot If aisles are constructed of a more conventional, impermeable material suitable for heavier vehicle use, such as asphalt, stalls can be constructed of permeable pavement. This can reduce the overall impervious surface coverage of a typical double loaded parking lot by 60% and avoid the need for an underground drainage system. Permeable stalls can be constructed of a number of materials including pervious concrete, unit payers such as brick or stone spaced to expose a permeable joint and set on a permeable base, crushed aggregate, porous asphalt, turf block, and cobbles in low traffic areas. Turf blocks and permeable joints are shown in Figures 3-7 and 3-8. Figure 3-8 Permeable Joints January 2003 CalIfornia Stormwater BMP Handbook 1-7 Section 3 SO I Facility Design for Water Quality Protection IDarking Grove A variation on the permeable stall design, a grid of trees and bollards can be used to delineate parking stalls and create a "parking grove." If the bollard and tree grids are spaced. approximately 19 ft apart, two vehicles can park between each row of the grid. This 9.5 ft stall spacing is slightly more generous that the standard 8.5 to 9 ft stall, and allows for the added width of the tree trucks and bollards. A benefit of this design is that the parking grove not only shades parked cars, but also presents an attractive open space when cars are absent. Examples of parking groves are shown in Figures 3-9 and 3-10. Figure 3-9 Figure 3-10 Parking Grove Parking Grove Overflow Parking Parking lot design often is required to accommodated peak demand, generating a high proportion of impervious land coverage of very limited usefulness. An alternative is to differentiate between regular and peak parking demands, and to construct the peak parking stalls of a different, more permeable, material. This "overflow parking" area can be made of a turf block, which appears as a green lawn when not occupied by vehicles or crushed stone or other materials. See Figure 3..1 The same concept can be applied to p( ith temporary parking needs, such as L-.rgency access routes, or in residential applications, RV, or trailer parking. qIezvd.n/&..asioa sU, (as swf&) Figure 3-11 Overflows Parking I_-. ----.---.----.---=-----. 3-8 California Stormwater BMP Handbook _inuflfll Section 3 Site and Facility Design for Water Quality Protection Porous Pavement Recharge Bed In some cases, parking lots can be designed to Figure 3-12 Porous Pavement Recharge Bed 3.2.3 Driveways Driveways can comprise up to 40% of the total transportation network in a conventional development, with streets, turn-arounds, and sidewalks comprising the remaining 60%. riveway length is generally determined by garage setback requirements, and width is usually andated by municipal codes and ordinances. If garages are setback from the street, long ' driveways are required, unless a rear alley system is included to provide garage access. If parking for two vehicles side by side is required, a 20 ft minimum width is required. Thus, if a 20 ft setback and a two car wide driveway are required, a minimum of 400 fta of driveway win result, or 4% of a typical io,000 fta residential lot. If the house itself is compact, and the driveway is long, wide, and paved with an impervious material such as asphalt or concrete, it can become the largest component of impervious land coverage on the lot. Municipalities can reduce the area dedicated to driveways by allowing for tandem parking (one vehicle in front of another on a narrow driveway). Also, if shared driveways are permitted, then two or more garages can be accessed by a single driveway, further reducing required land area. Rear alley access to the garage can reduce driveway length, but overall impervious surface coverage may not be reduced if the alleys are paved with impervious materials and the access streets remain designed to conventional municipal standards. Alternative solutions that work to reduce the impact of water quality problems associated with impervious land coverage on city streets also work on driveways. Sloping the driveway so that it drains onto an adjacent turf or groundcover area prevents driveways from draining directly to storm drain systems. This concept is shown in Figures 3-13 and 3-14. Use of turf-block or unit payers on sand creates attractive, low maintenance, permeable driveways that filter stormwater. See Figure 3-15. Crushed aggregate can serve as a relatively smooth pavement with minimal ---aintenance as shown in Figure 3-16. Paving only under wheels (Figure 3-17) is a.viable, ( expensive design if the driveway is straight between the garage and the street and repaving temporary parking areas with permeable unit payers such as brick or stone can significantly reduce the percentage of impervious area devoted to the driveway. January 2003 CalIfornia Stormwater BMP Handbook -- 3-9 kI, perform more complex stormwater management functions. Constructing a stone-filled reservoir below the pavement surface and directing runoff underground by means of perforated distribution pipes can achieve subsurface stormwater storage and infiltration as shown in Figure 3-12. Subsurface infiltration basins eliminate the possibilities of mud, mosquitoes and safety hazards sometimes perceived to be associated with ephemeral surface drainage. They also can provide for storage of large volumes of runoff, and can be incorporated with roof runoff collection systems. &viw4 Figure 3-14 Alternative Solution Slopes Flow to Groundcover dmw,&w to au WSWMAMW Section 3 nd Facility Design for Water Quality Protection Figure 3-13 Traditional Design Drains Flow Directly to Storm Drain Figure 3-16 Figure 3-15 Crushed Aggregate Unit Payers ..f. L __LL Figure 3-17 Paving Only Under Wheels 3-10 California Stormwater BMP Handbook January 2003 Section 3 Site and Facility Design for Wafer Quality Protection 3.2.4 Landscape and Open Space In the natural landscape, most soils infiltrate a high percentage of rainwater through a complex web of organic and biological activities that build soil porosity and permeability. Roots reach into the soil and separate particles of day, insects excavate voids in the soil mass, roots decay leaving networks of macro pores, leaves fall and form a mulch over the soil surface, and earthworms burrow and ingest organic detritus to create richer, more porous soil. These are just a few examples of the natural processes that occur within the soil. Maintenance of a healthy soil structure through the practice of retaining or restoring native soils where possible and using soil amendments where appropriate can improve the land's ability to filter and slowly release stormwater into drainage networks. Construction practices such as decreasing soil compaction, storing topsoil on-site for use after construction and chipping wood for mulch as it is cleared for the land can improve soil quality and help maintain healthy watersheds. Practices that reduce erosion and help retain water on-site include incorporating organic amendments into disturbed soils after construction, retaining native vegetation, and covering soil during revegetation. Subtle changes in grading can also improve infiltration. Landscape surfaces are conventionally graded to have a slight convex slope. This causes water to run off a central high point into a ( rrounding drainage system, creating increased runoff. If a landscape surface is graded to have (\ - slightly concave slope, it will hold water. The infiltration value of concave vegetated surfaces is greater in permeable soils. Soils of heavy day or underlain with hardpan provide less infiltration value. In these cases concave vegetated surfaces must be designed as retention/detention basins, with proper outlets or under drains to an interconnected system. Multiple Small Basins Biofilters, infiltration, retention/detention basins are the basic elements of a landscape designed for sturmwater management. The challenge for designers is to integrate these elements creatively and attractively in the landscape - either within a conventional landscape aesthetic or by presenting a different landscape image that emphasizes the role of water and drainage. Multiple small basins can provide a great deal of water storage and infiltration capacity. These small basins can fit into the parkway planting strip or shoulders of street rights-of-way. If connected by culverts under walks and driveways, they can create a continuous linear infiltration system. Infiltration and retention/detention basins can be placed under wood decks, in parking lot planter islands, and at roof downspouts. Outdoor patios or seating-areas can be sunken a few steps, paved with a permeable pavement such as flagstone or gravel, and designed to hold a few inches of water collected from surrounding rooftops or paved areas for a few hours after a rain. All of these are examples of small basins that can store water for a brief period, allowing it to ifiltrate into the soil, slowing its release into the drainage network, and filtering pollutants. An ('\ rdinary lawn can be designed to hold a few inches of water for a few hours after a storm, attracting birds and creating a landscape of diversity. Grass/ vegetated swales can be integrated with landscaping, providing an attractive, low maintenance, linear biofilter. Extended detention (dry ponds) store water during storms, holding runoff to predevelopment levels. Pollutants Section 3 '- -rid Facility Design for Water Quality Protection C settle and are removed from the water column before discharging to streams. Wet ponds serve a similar purpose and can increase property values by providing a significant aesthetic, and passive recreation opportunity. Plant species selection is critical for proper functioning of infiltration areas. Proper selection of plant materials can improve the infiltration potential of landscape areas. Deep-rooted plants help to build soil porosity. Plant leaf-surface area helps to collect rainwater before it lands on the soil, especially in light rains, increasing the overall water-holding potential of the landscape. A large number of plant species will survive moist soils or periodic inundation. These plants provide a wide range of choices for planted infiltration/detention basins and drainage swales. Most inundated plants have a higher survival potential on well-drained alluvial soils than on fine textured shallow soils or clays. MaintenRnce Needs for Stormwater Systems All landscape treatments require maintenance Landscapes designed to perform stormwater management functions are not necessarily more maintenance intensive than highly manicured conventional landscapes. A concave lawn requires the same mowing, fertilizing and weeding as a convex one and often less irrigation because more rain is filtered into the underlying soil. Svmiimes infiltration basins may require a different kind of maintenance than conventionally ed. i,pical maintenance activities include periodic inspection of surface drainage systems to ensure clear flow lines, repair of eroded surfaces, adjustment or repair of drainage structures, soil cultivation or aeration, care of plant materials, replacement of dead plants, replenishment of mulch cover, irrigation, fertilizing, pruning and mowing. Also, dead or stressed vegetation may indicate chemical dumping Careful observation should be made of these areas to determine if such a problem exists. Landscape maintenance can have a significant impact on soil permeability and its ability to support plant growth. Most plants concentrate the majority of their small absorbing roots in the upper 6 in. of the soil surface if a mulch or forest litter protects the surface. If the soil is exposed or bare, it can become so hot that surface roots will not grow in the upper 8 to 10 in. The common practice of removing all leaf litter and detritus with leaf blowers creates a hard-crusted soil surface of low permeability and high heat conduction. Proper mulching of the soil surface improves water retention and infiltration, while protecting the surface root zone from temperature extremes. In addition to impacting permeability, landscape maintenance practices can have adverse effects on water quality. Because commonly used fertilizers and herbicides are a source of organic compounds, it is important to keep these practices to a minimum, and prevent over watering. W veil maintained and designed, landscaped concave surfaces, infiltration basins, swales ' retention areas can add aesthetic value while providing the framework for ..ivironmentally sound, comprehensive stormwater management systems. 3-12 CalIfornia Starmwater BMP Handbook Section 3 Site and Facility Design for Water Quality Pmfaction Street Trees Trees improve water quality by intercepting and storing rainfall on leaves and branch surfaces, thereby reducing runoff volumes and delaying the onset of peak flows. A single street tree can have a total leaf surface area of several hundred to several thousand ft2, depending on species and size. This aboveground surface area created by trees and other plants greatly contributes to the water holding capacity of the land. They attenuate conveyance by increasing the soil's capacity to filter rainwater and reduce overland flow rates. By diminishing the impact of raindrops on unvegetated soil, frees reduce soil erosion. Street trees also have the ability to reduce ambient temperature of stormwater runoff and absorb surface water pollutants. When using street trees to achieve stormwater management goals, it is important to use tree species with wide canopies. Street tree design criteria should specify species expected to attain 20 to 30 ft canopies at maturity. Planter strips with adequate width and depth of soil volume are necessary to ensure tree vitality and reduce future mnintenance. Structural soils also provide rooting space for large trees and can be specified along narrow planter strips and underneath sidewalks to enable continuous belowground soil and root connections. 3.2.5 Outdoor Work Areas 71ie site design and landscape details listed In previous sections are appropriate for uses where w concentrations of pollutants can be mitigated through infiltration, retention and detention. ujten in commercial and industrial sites, there are outdoor work area in which a higher concentration of pollutants exists, and thus a higher potential of pollutants infiltrating the soil. These work areas often involve automobiles, equipment machinery, or other commercial and industrial uses, and require special consideration. Outdoor work areas are usually isolated elements in a larger development Infiltration and detention strategies are still appropriate for and can be applied to other areas of the site, such as parking lots, landscape areas, employee use areas, and bicycle path. it is only the outdoor work area within the development - such as the loading dock fueling area, or equipment wash area - that requires a different drainage approach. This drainage approach is often precisely the opposite from the infiltration/detention strategy - in other words, collect and convey. In these outdoor work areas, infiltration is discouraged and runoff is often routed directly to the sanitary sewer, not the storm drain. Because this runoff is being added to the loads normally received by the water treatment plants (publicly owned treatment works - POTWs), it raises several concerns that must be addressed in the planning and design stage. These include: Higher flows that could exceed the sewer system capacity Catastrophic spills that may cause harm to POTW operation A potential increase in pollutants These concerns can be addressed at policy, management, and site planning levels. C. Section 4 Source Control BMPs 4.1 Introduction This section describes specific source control Best Management Practices (BMPs) to be considered for incorporation into newly developed public and private infrastructure, as well as retrofit into existing facilities to meet stormwater management objectives. 4.2 BMP Fact Sheets Source control fact sheets for design are listed in Table 4-1. The fact sheets detail planning methods and concepts that should be taken into consideration by developers during project design. The fact sheets are arranged in three categories: those that have to do with landscape, irrigation, and aignage considerations; those that have to do with use of particular materials, those that have to do with design of particular areas. 4.3 Fact Sheet Format A BMP fact sheet is a short document that provides information about a particular BMP. 1ypically each fact sheet contains the information outlined in Figure 4-1. Supplemental information is provided if it is available. The fact sheets also contain side bar presentations with information on BMP design objectives. Completed fact sheets for each of the above activities are provided in Section 4.4. Table 4-1 Source Control BMPs for Design Design SD-lo, Site Design and Landscape Planning SD-u Roof Runoff Controls SD-I2 Efficient Irrigation SD-13 Storm Drain System Signs Materials SD-20 Pervious Pavements SD-at Alternative Building Materials Are" SD-30 Fueling Areas SD-31 Maintenance Bays and Docks SD-Na Trash Enclosures SD-33 VaNiWasbIngAreas SD-34 Outdoor Material Storage Areas SD-35 Outdoor WorkAreas SD-36 Outdoor Processing Areas SDxx Example Fact Sheet Description of the BMP Apprnsch Suitable Applications Design Considerations Designing New Installations Redeveloping Existing Installations Supplemental Information Examples Other Resources 4.4 BMP Fact Sheets Source Control BMP Fact Sheets for design follow. The BMP fact sheets are individually page numbered and are suitable for photocopying and inclusion in stormwater quality management plans. Fresh copies of the fact sheets can be individually downloaded from the California Stormwater BMP Handbook website at www.cabmphandbooks.com. Figure 4-1 Example Fact Sheet January 2003 California Stormwater BMP Handbook 4-1 M . _I -. Site Design & Landscape Planning SD-10 - Design Objectives 1 Maximize Infiltration I Provide Retention 1 Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description Each project site possesses unique topographic, hydrologic, and vegetative features, some of which are more suitable for development than others. Integrating and incorporating appropriate landscape planning methodologies into the project design is the most effective action that can be done to minimize surface and groundwater contamination from stormwater. Approach Landscape planning should couple consideration of land suitability for urban uses with consideration of community goals and projected growth. Project plan designs should conserve natural areas to the extent possible, maximize natural water storage and infiltration opportunities, and protect slopes and channels. Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. Design Considerations Design requirements for site design and landscapes planning should conform to applicable standards and specifications of agencies with jurisdiction and be consistent with applicable General Plan and Local Area Plan policies. ICASC 5torntwater Ouaft I Association January 2003 CalIfornia Stormwater BMP Handbook l -t A 5" .10 Site Design & Landscape Planning Designing New Installations - Begin the development of a plan for the landscape unit with attention to the following general principles: Formulate the plan on the basis of clearly articulated community goals. Carefully identify conflicts and choices between retaining and protecting desired resources and community growth. Map and assess land suitability for urban uses. Include the following landscape features in the assessment: wooded land, open unwooded land, steep slopes, erosion-prone soils, foundation suitability, soil suitability for waste disposal, aquifers, aquifer recharge areas, wetlands, floodplains, surface waters, agricultural lands, and various categories of urban land use. When appropriate, the assessment can highlight outstanding local or regional resources that the community determines should be protected (e.g., a scenic area, recreational area, threatened species habitat, farmland, fish run). Mapping and assessment should recognize not only these resources but also additional areas needed for their sustenance. Project plan designs should conserve natural areas to the extent possible, maximize natural water storage and infiltration opportunities, and protect slopes and channels. Cc ,e Natural Areas during Landscape Planning (k, -pacable, the following items are required and must be implemented in the site layout uring the subdivision design and approval process, consistent with applicable General Plan and Local Area Plan policies: Cluster development on least-sensitive portions of a site while leaving the remaining land in a natural undisturbed condition. Limit clearing and grading of native vegetation at a site to the minimum amount needed to build lots, allow access, and provide fire protection. Maximize trees and other vegetation at each site by planting additional vegetation, clustering tree areas, and promoting the use of native and/or drought tolerant plants. Promote natural vegetation by using parking lot islands and other landscaped areas. Preserve riparian areas and wetlands. Maximize Natural Water Storage and Infiltration Opportunities Within the Landscape Unit Promote the conservation of forest cover. Building on land that is already deforested affects basin hydrology to a lesser extent than converting forested land. Loss of forest cover reduces interception storage, detention in the organic forest floor layer, and water losses by evapotranspiration, resulting in large peak runoff increases and either their negative effects or the expense of countering them with structural solutions. intain natural storage reservoirs and drainage corridors, including depressions, areas of permeable soils, swales, and intermittent streams. Develop and implement policies and 2 of 4 California Stormwater BMP Handbook )anuary 2003 TflLandscape Planning D10 regulations to discourage the clearing, filling, and channelization of these features. Utilize them in drainage networks in preference to pipes, culverts, and engineered ditches. Evaluating infiltration opportunities by referring to the stormwater management manual for the jurisdiction and pay particular attention to the selection criteria for avoiding groundwater contamination, poor soils, and hydrogeological conditions that cause these facilities to fail. If necessary, locate developments with large amounts of impervious surfaces or a potential to produce relatively contaminated runoff away from groundwater recharge areas. Protection of Slopes and Channels during Landscape Design Convey runoff safely from the tops of slopes. Avoid disturbing steep or unstable slopes. Avoid disturbing natural channels. Stabilize disturbed slopes as quickly as possible. Vegetate slopes with native or drought tolerant vegetation. Control and treat flows in landscaping and/or other controls prior to reaching existing natural drainage systems. Stabilize temporary and permanent channel crossings as quickly as possible, and ensure that increases in run-off velocity and frequency caused by the project do not erode the channel. Install energy dissipaters, such as riprap, at the outlets of new storm drains, culverts, conduits, or channels that enter unlined channels in accordance with applicable specifications to minimize erosion. Energy dissipaters shall be installed in such a way as to minimize impacts to receiving waters. Line on-site conveyance channels where appropriate, to reduce erosion caused by increased flow velocity due to increases in tributary impervious area. The first choice for linings should be grass or some other vegetative surface, since these materials not only reduce runoff velocities, but also provide water quality benefits from filtration and infiltration. If velocities in the channel are high enough to erode grass or other vegetative linings, riprap, concrete, soil cement, or geo-grid stabilization are other alternatives. Consider other design principles that are comparable and equally effective. 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 pervious surfaces. The definition of" redevelopment" must be consulted to determine tether 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. January 2003 -California Storm-water BMP Kandbank 1 7A Redevelopment may present sigiificant opportunity to add features which had not previously been implemented. Examples include incorporation of depressions, areas of permeable soils, and swales in newly redeveloped areas. While some site constraints may exist due to the status of already existing infrastructure, opportunities should not be missed to maximize infiltration, slow runoff, reduce impervious areas, disconnect directly connected impervious areas. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Stormwater Management Manual for Western Washington, Washington State Department of Ecology, August 2001. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February i, 200. 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, J-1-1002. (L 4 of 4 California Stormwater BMP Handbook nn Sediment Basin 5E2 Objectives Description and Purpose A sediment basin is a temporary basin formed by excavation or by constructing an embankment so that sediment-laden runoff is temporarily detained under quiescent conditions, allowing sediment to settle out before the runoff is discharged. Suitable Applications Sediment basins may be suitable for use on larger projects with sufficient space for constructing the basin. Sediment basins should be considered for use: Where sediment-laden water nay' enter the drainage system or watercourses On construction projects with disturbed areas during the rainy season At the outlet of disturbed watersheds between 5 acres and 75 acres At the outlet of large disturbed watersheds, as necessary Where post construction detention basins are required In association with dikes, temporary channels, and pipes used to convey runoff from disturbed areas Limitations Sediment basins must be installed only within the property limits and where failure of the structure will not result in loss of life, damagétó homes or buildings, or interruption of use or service of EC Erosion Control SE Sediment Control / TC Tracking Control WE Wind Erosion Control NS Non-Stormwater Management Control Waste Management and WM Materials Pollution Control Legend: 1 Primary Objective I Secondary Objective Targeted Constituents Sediment I Nutrients Trash I Metals Bacteria Oil and Grease Organics Potential Alternatives SE-3 Sediment Trap (for smaller areas) Jc 4SQ JCallfornla Stormwater .$?$ Quality Auoclaton January 2003 CalifOrniaStormwater BMP Handbook 1 o 12¼ Construction - - www.cabmphandbooks.com S ' ISTORM WATER REQUIREMENTS APPLICABILITY CHECKLIST I Project Address Assessors Parcel Number(s): Project # (city use only): Cannon Road & El Camino Real 208-010-36-00 Complete Sections 1 and 2 of the following checklist to determine your project's permanent and construction storm water best management practices requirements. This form must be completed and submitted with your permit application. Section 1. Permanent Storm Water BMP Requirements: If any answers to Part A are answered "Yes," your project is subject to the "Priority Project Permanent Storm Water BMP Requirements," and 'Standard Permanent Storm Water BMP Requirements" in Section Ill, "Permanent Storm Water BMP Selection Procedure" in the Storm Water Standards manual. If all answers to Part A are "No," and any answers to Part B are "Yes," your project is only subject to the "Standard Permanent Storm Water BMP Requirements". If every question in Part A and B is answered "No," your project is exempt from permanent storm water requirements. Part A: Determine Priority Project Permanent Storm Water BMP Requirements. Does the project meet the definition of one or more of the priority project categories?* Yes No Detached residential development of 10 or more units. El] FAI Attached residential development of 10 or more units. LI Fx1 Commercial development greater than 100,000 square feet. El I Fx] 1 Automotive repair shop. III EiII Restaurant. LI Fx] Steep hillside development greater than 5,000 square feet. F] Project discharging to receiving waters within Environmentally Sensitive Areas. Parking lots greater than or equal to 5,000 ft or with at least 15 parking spaces, and O EJ potentially exposed to urban runoff. - Streets, roads, highways, and freeways which would create a new paved surface that is feet x 5,000 square or greater * Refer to the definitions section in the Storm Water Standards for expanded definitions of the - priority project categories. Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered priority projects. Parking lots, buildings and other structures associated with utility projects are priority projects if one or more of the criteria in Part A is met. If all answers to Part A are "No", continue to Part B. Part B: Determine Standard Permanent Storm Water Requirements. Does the project propose: Yes No New impervious areas, such as rooftops, roads, parking lots, driveways, paths and El -[i] sidewalks? New pervious landscape areas and irrigation systems? Fil 1:11 Permanent structures within 100 feet of any natural water body? E1 Trash storage areas? Liquid or solid material loading and unloading areas? El El Vehicle or equipment fueling, washing, or maintenance areas? Fl- Require a General NPDES Permit for Storm Water Discharges Associated with Industrial - 1:1- - Fl Activities (Except construction)?* Commercial or industrial waste handling or storage, excluding typical office or household El Fil waste? Any grading or ground disturbance during construction? E1 III Any. new storm drains, or alteration to existing storm drains? 1111 *To find out if your project is required to obtain an-individual General NPDES Permit for Storm Water Discharges Associated with Industrial Activities, visit the State Water Resources Control Board web site at, www.swrcb.ca.gov/stormwtr/industrial.htmi Section 2. Construction Storm Water BMP Requirements: If the answer to question I of Part C is answered "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Storm Water Pollution Prevention Plan (SWPPP). If the answer to question I is "No," but the answer to any of the remaining questions is "Yes," your project is subject to Section IV, "Construction Storm Water BMP Performance Standards," and must prepare a Water Pollution Control Plan (WPCP). If every question in Part C is answered "No," your project is exempt from any construction storm water BMP requirements. If any of the answers to the questions in Part C are "Yes," complete the construction site prioritization in Part D, below. Part C: Determine Construction Phase Storm Water Requirements. Would the project meet any of these criteria during construction? Yes No Is the project subject to California's statewide General NPDES Permit for Storm Water Discharges Associated With Construction Activities? Does the project propose grading or soil disturbance? Ei LII Would storm water or urban runoff have the potential to contact any portion of the construction area, including washing and staging areas? x - - - Would the project use any construction materials that could negatively affect water quality if discharged from the site (such as, paints, solvents, concrete, and stucco)? - - Part D: Determine Construction Site Priority In accordance with the Municipal Permit; each construction site with construction storm water BMP requirements must be designated with a priority: high, medium or low. This prioritization must be completed with this form, noted on the plans, and included in the SWPPP or WPCP. Indicate the project's priority in one of the check boxes using the criteria below, and existing and surrounding conditions of the project, the type of activities necessary to complete the construction and any other extenuating circumstances that may pose a threat to water quality. The City reserves the right to adjust the priority of the projects both before and during construction. [Note: The construction priority does NOT change construction BMP requirements that apply to projects; all construction BMP requirements must be identified on a case-by-case basis. The construction priority does affect the frequency of inspections that will be conducted by City staff. See Section IV.1 for more details on construction BMP requirements.] A) High Priority Projects where the site is 50 acres or more and grading will occur during the rainy season Projects I acre or more. Projects 1 acre or more within or directly adjacent to or discharging directly to a coastal lagoon or other receiving water within an environmentally sensitive area Projects, active or inactive, adjacent or tributary to sensitive water bodies B) Medium Priority Capital Improvement Projects where grading occurs, however a Storm Water Pollution Prevention Plan (SWPPP) is not required under the State General Construction Permit (i.e., water and sewer replacement projects, intersection and street re-alignments, widening, comfort stations, etc.) Permit projects in the public right-of-way where grading occurs, such as installation of sidewalk, substantial retaining walls, curb and gutter for an entire street frontage, etc. , however SWPPP5 are not required. Permit projects on private property where grading permits are required, however, Notice Of Intents (NOIs) and SWPPPs are not required. C) Low Priority Capital Projects where minimal to no grading occurs, such as signal light and loop installations, street light installations, etc. Permit projects in the public right-of-way where minimal to no grading occurs, such as pedestrian ramps, driveway additions, small retaining walls, etc. Permit projects on private property where grading permits are not required, such as small retaining walls, single-family homes, small tenant improvements, etc. Owner/Agent/Engineer Name (Please Print): Title: Signature: Date: RECEIVED FEB 2 3 2001 ENGINEERING DEPARTMENT