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CDP 05-46; MOSS; PRELIMINARY STORM WATER MANAGEMENT PLAN; 2007-07-06
Joseph p. Cohan PRELIMINARY STORM WATER MANAGEMENT PLAN For 5015 TIERRA DEL ORO July 6, 2007 Prepare(j By: Hofman Planning & Engineering 5900 Pasteur Court, Suite 150 CarlsbacJ, CA 92008 RCE 58873 Date Prepared by: JPC cop TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION 3 1.1 Hydrologic Unit Contribution 3 1.2 Beneficial Uses 3 2.0 CHARACTERIZATION OF PROJECT RUNOFF 5 2.1 Soil Characteristics 5 2.2 Potential Discharges 5 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY 3.1 Site Design BMP's 5 3.2 Treatment Control BMP's 6 3.3 Construction BMP's 6 4.0 MONITORING, INSPECTION AND REPORTING 7 ATTACHMENTS: 1. Vicinity Map 2. Beneficial uses for the hydrologic unit 3. 303(D) list for impaired water bodies 4. Table 2: Anticipated and potential pollutants 5. Table 1: Storm Water BMP Requirements Matrix 6. Site Design BMP's 7. Treatment Control BMP's 8. Project site plan and BMP map 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 67.871), 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 Coastal Development Permit. This project will provide guidelines in developing and implementing Best Management Practices (BMP's) for storm water quality during construction and post construction. A SWPPP may need to 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 BMP's, 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 of BMP's during the construction phase. 1.0 PROJECT DESCRIPTION 5015 Tierra Del Oro is currently a single-family residence. A coastal development permit is currently being processed for this residence which proposes the development of a new single-family residence. 1.1 Hydrologic Unit Contribution The project is located in the Agua Hedionda Hydrologic Sub area (904.31) of the Carlsbad Hydrologic Unit in the San Diego Region. Under existing conditions, storm runoff is collected in a drainage system and conveyed into the Pacific Ocean. The propose project will not alter the drainage discharge patterns on site. The increase in impervious area will be mitigated by landscaped swales and other source control BMP's. 1.2 Beneficial Uses The beneficial uses for the hydrologic unit are included in attachment 2, and the definitions are listed below. This information comes from the Water Quality Control Plan for the San Diego Basin. 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. NAV - Navigation: Includes uses of water for shipping, travel, or other transportation by private, military, or commercial vessels. 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. BIOL - Preservation of Biological Habitats of Special Significance: Includes the uses of water that support designated areas or habitats, such as established refuges, parks, sanctuaries, ecological reserves, or Areas of Special Biological Significance (ASBS), where the preservation pr enhancement of natural resources requires special protection. WILD - Wildlife Habitat: Includes the 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. RARE - Rare, Threatened, or Endangered Species: Includes uses of water that support habitat 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. MAR - Marine Habitat: Includes uses of water that support marine 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. AQUA - Aquaculture: Includes the uses of water for aquaculture or Mari culture operations including, but not limited tom propagation, cultivation, maintenance, or harvesting of aquatic plants and animals for human consumption or bait purposes. 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. SPWN - Spawning, Reproduction, and/or Early Development: Includes uses of water that support high quality aquatic habitats suitable for reproduction and early development of fish. This use is applicable only for the protection of anadromous fish. SHELL - Shellfish Harvesting: 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 support purposes. 2.0 CHARACTERIZATION OF PROJECT RUNOFF According to the California 1998 303d list published by RWQCB (attachment 3), Agua Hedionda Lagoon is an impaired water body associated with the direct stormwater discharge from this project. Agua Hedonda Lagoon has low priority impairment for high coli form count and medium priority for sedimentation/siltation. 2.1 Soil Characteristics The project area consists entirely of soil group B. 2.2 Potential Discharges There is no sampling data available for the existing site condition. 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 4). It includes antidpated pollutants for detached residential development. • Sediments • Nutrients from fertilizers • Trash and debris • Oxygen demanding substances • Oil and grease from paved areas • Bacteria and Viruses • Pestiddes from landscaping 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY To address water quality for the project, BMP's will be implemented during construction and post construction. Required BMP's are selected from Table 1: Storm Water BMP requirements Matrix, of the City of Carlsbad's Storm Water Standards Manual (attachment 5). 3.1 Site Design BMP's 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 6 for details). Site design and Landscape Planning SD-10: To the maximum extent practicable, parking lots, sidewalks, patios, roof top drains, rain gutters, and other impervious surfaces shall drain into adjacent landscaping prior to discharging to the storm water conveyance system. Use Efficient Irrigation Systems SD-12: Irrigation systems shall employ rain shutoff devices to prevent irrigation during precipitation and be designed to limit runoff. Trash Storage Areas SD-32: All trash containers shall contain attached lids that exdude rain or contain a roof or awning to minimize direct precipitation. 3.2 Treatment Control BMP's As identified in Table 1, a combination of treatment control BMP's shall be incorporated into the project. The project has been designed so that runoff is treated by Site Design BMP's prior to Structural Treatment BMP's. Vegetated Buffer Strip TC-31: Runoff will be conveyed through a vegetated buffer strip prior to entering the street (see attachment 7 for details). Basins are expected to produce the pollutants listed in section 2.2 of this report. Vegetated buffer strips are effective treatment control BMP's with maximum pollutant removal effidency for the particular pollutants of concern to the maximum extent practicable. 3.3 Construction BMP's The following is a list of potential construction phase BMP's to be used. 1. Silt fence, fiber rolls, or gravel bag berms. 2. Check dams 3. Street sweeping and vacuuming 4. Storm drain inlet protection 5. Stabilized construction entrance/exit 6. Vehicle and equipment maintenance, cleaning and fueling 7. Hydroseed, soil binders, or straw mulch 8. Material delivery and storage 9. Stockpile management 10. Spill prevention and control 11. Waste management for solid, liquid, hazardous and sanitary waste, contaminated soil 12. Concrete waste management A SWPPP will be prepared and approved prior to issuance of a grading permit. Construction BMP's 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. -6- 4.0 MONITORING, INSPECTION AND REPORTING During construction, the BMP's 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 BMP's. 7- VICINITY MAP CITY OF OCEANSIDE PROJECT SITE NOT TO SCALE CITY OF VISTA CITY OF SAN MARCOS PACIFIC OCEAN CITY OF ENCINITAS Table 2-3. BENEFICIAL USES OF COASTAL WATERS BENEFICIAL USE Coastal Waters Hydrologic 1 N N R R C B E W R M A M S W S Coastal Waters Unit Basin 1 N A E E 0 1 S 1 A A Q 1 P A H Number D V C C M 0 T L R R U G w R E Number 1 2 M L D E A R N M L L pacific Ocean • • • • • • • • • • • • Dana Point Harbor • • • • • • • • • • Del Mar Boat Basin • • • • • • • • • • • Mission Bay • • • • • • • • • • • Oceanside l-larbor • • • • • • • • • • • San Diego Bay ^ • • • • • • • • • • • • Coastal Lagoons Tijuana River Estuary 11.-il • • • • • • • • • • • Mouth of San Diego River 7.11 • • • • • • • • • • Los Penasquitos Lagoon ^ 6.10 • • • • • • • • • • San Dieguito Lagoon 5.11 • • • • • • • • • Batiquitos Lagoon 4.51 • • • • • • • • • San Elijo Lagoon 5.61 • • • • • • • • • Aqua Hedionda Lagoon 4.31 • • • • • • • • • • • ^ Includes the tidal prisms of the Otay and Sweetwater Rivers. 2 Fishing from shore or boat permitted, but other water contact recreational (REC-1) uses are prohibited. # Existing Beneficial Use Table 2-3 BENEFICIAL USES 2-47 March 12, 1997 H o H HH < c o ^ r. Z hH C o 5!5 w o H U V© o o ti O o as &d EQ o H o o <: Q < > o a. CS u Z to CO H Z o e.. It BM > H Z o e e 01 < 0\ o 9^ o t- s e s e as e Z B S I h S 5 - -S 1 I I G o 0. _B -© a, B e Z .V to ° s c> £ B- 5 o cc Q O 5 S o " = S Z a B s e e B B 3 3 I .^6 1 storm Water Standards 4/03/03 III. PERMANENT BEST MANAGEMENT PRACTICES SELECTION PROCEDURE When referred to this Section, by Step 2 of Section II, complete the analysis required for your project in the subsections of Section III.1 below. 1. A IDENTIFY POLLUTANTS & CONDITIONS OF CONCERN Identify Pollutants from the Project Area Using Table 1, identify the project's anticipated pollutants. Pollutants associated with any hazardous material sites that have been remediated 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 categories that apply. General Pollutant Categories Project Categories cSedtments" Tlutrients Heavy ISleterts- Organic "Compounds Trash & DobriC' Oxygen Demanding Substances Oil& Grease^ Bacteria & \/inigp<; Rfisficides "^tached Residential Development X X X X X X X J Attached Residential Development X X X R(i) RP) Rd) X Commercial Development >100,000 ft2 Pd) Rd) R(2) X R(5) X R(3) R(5) Automotive Repair X XWP) X X Restaurants X X X X Millside Development >5,000ft2 X X X X X X Parking Lots Rd) R(1> X X R(1) X Rd) Streets, Highways & Freeways X pd)x X XC) X R(5) X X = anticipated P = potential (1) A potential pollutant if landscaping exists on-site. (2) A potential pollutant ifthe project includes uncovered parking areas. (3) A potential pollutant if land use involves food or animal waste products. (4) Including petroleum hydrocarbons. (5) Including solvents. 12 Storm Water Standards 4/03/03 Table 1. Standard Development Project & Priority Project Storm Water BMP Requirements Matrix S/te Design BMPs(i) Source Confro/ BMPs(^) BMPs Applicable to Individual Priority Project Categories(^) Treafmenf Confro/ BMPs(^ S/te Design BMPs(i) Source Confro/ BMPs(^) a. Rrivate Roads b. Residential Driveways & Guest Rarking 0. Dock Areas d. Maintenance Bays e. Vehicle Wash Areas f. Equipment Wash Areas g. Outdoor Processing Areas h. Surface Rarking Areas i. Fueling Areas j. Hillside Landscaping Treafmenf Confro/ BMPs(^ Standard Projects R R 0 0 0 0 0 0 0 0 0 0 0 Priority P-Eojacts- — — ^Detached Residential L Development R R R R R Attached Residential Development R R R s Commercial Development >100,000ft2 R R R R R R s Automotive Repair Shop R R R R R R R s Restaurants R R R R s Hillside Development >5,000ft2 R R R R s Rarking Lots R R R(5) s Streets, Highways & Freeways R R s R = Required; select one or more applicable and appropriate Bl\/ Rs from t ie applicable steps in Section III.2.A-D, or equivalent as identified in Appendix C. 0 = Optional/ or may be required by City staff. As appropriate, applicants are encouraged to incorporate treatment control BMRs and BMRs applicable to individual priority project categories into the project design. City staff may require one or more ofthese BMPs, where appropriate. 8 = Select one or more applicable and appropriate treatment control BMRs from Appendix C. (1) Refer to Section III.2.A. (2) Refer to Section III.2.B. (3) Priority project categories must apply specific storm water BMR requirements, where applicable. Rriority projects are subject to the requirements of all priority project categories that apply. (4) Refer to Section III.2.D. (5) Applies if the paved area totals >5,000 square feet or with >15 paricing spaces and is potentially exposed to urban runoff. 8 Design & Landscape Planning SD-10 Design Objectives 0 Maximize InfUtration 0 Provide Retention M Slow Runoff Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants El 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 mii-umize 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 apphcations 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. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 1 of 4 SD-10 Site Design & Landscape Planning Designing New Installatiojis Begin the development of a plan for the landscape miit with attention to the following general principles: • Fonnulate the plan on the basis of clearly articulated conmmnity goals. Carefully identify conflicts and choices between retaining and protecting desired resources and comnranity growth. • Map and assess land suitabiUty for urban uses. Include the following landscape features in the assessment: wooded land, open unwooded land, steep slopes, erosion-prone soils, foundation suitability, soil suitabiUty 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 higliUglit outstanding local or regional resources that the commmiity determines should be protected (e.g., a scenic area, recreational area, threatened species habitat, farmland, fish nm). Mapping and assessment should recogmze not only tiiese 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. Conserve Natural Areas during Landscape Plannmg If appUcable, the following items are required and must be implemented in the site layout during the subdivision design and approval process, consistent with appUcable General Plan and Local Area Plan poUcies: • 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 niinimum amount needed to build lots, allow access, and provide fire protection. • Maximize trees and other vegetation at eadi 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 weflands. Maximize Natural Water Storage and Infiltration Opportimities Within the Landscape Unit m Promote tlie conservation of forest cover. Building on land that k already deforested affects basin hydrology to a lesser extent tlian converting forested land. Loss of forest cover reduces interception storage, detention in tlie organic forest floor layer, and water losses by evapotranspiration, resulting in large peak runoff increases and either their negative effects or the expense of comitering them -with structural solutions. • Maintain natural storage reservoirs and drainage corridors, including depressions, areas of permeable soils, swales, and intermittent streams. Develop and implement poUcies and 2 of 4 Califomia Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandboote.com Site Design & Landscape Planning SD-10 regulations to discourage the clearing, filling, and clianneUzation of these features. Utilize them in drainage networks in preference to pipes, culverts, and engineered ditches. • Evaluating infiltration opportunities by referring to the stomiwater 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 a-way fix>m groundwater recharge areas. Protectton of Slopes and Cliannels during Landscape Design m Convey runoff safely from the tops of slopes. • Avoid disturbing steep or imstable slopes. • Avoid disturbing natural channels. m StabiUze 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 cliannel crossings as quiddy as possible, and ensure that increases in run-off veiodty and frequency caused by the project do not erode the chaimel. • InstaU energy dissipaters, such as riprap, at the outlets of new storm drains, culverts, conduits, or cliannels that enter unUned channels in accordance with applicable specifications to minimize erosion. Energy dissipaters shall be installed in such a way as to minimize impacts to recei-ving 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 rmioff velocities, but also provide water quaUty benefits from filtration and infiltration. If velodties in the channel are high enough to erode grass or other vegetative linings, riprap, concrete, soil cement, or geo-grid stabilization are other alternatives. a Consider otiier design prindples that are comparable and equally effective. Redeveloping Existing Installations Variousjurisdictional 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 tlie definition appUes, the steps outlined under "designing new installations" above should be foUowed. January 2003 Califomia Stonnwater BMP Handbook 3 of 4 New Development and Redevelopment www.cabmphandbooks.com SD-10 Site Design & Landscape Planning Redevelopment may present significant 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 Stonnwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Stormwater Management Manual for Westem Washington, Wasliington 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, Febraary 14, 2002. Model Water QuaUty Managenient Plan (WQMP) for County of Orange, Orange Coimty Flood Control District, and the Incorporated Cities of Orange County, Draft Febraary 2003. Ventura Comitywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 4 of 4 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandboote.com Efflcient Irrigation SD-12 Design Objectives EI Maximize Infiltration 0 Provide Retenfion 0 Stow Runoff Minimize Impen/ious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Description Irrigation water provided to landscaped areas may result in excess irrigation water being conveyed into stormwater drainage systems. Approach Project plan designs for development and redevelopment should indude application methods of irrigation water that minimize mnoff of excess irrigation water into the stomiwater conveyance system. Suitable Applications Appropriate appUcations include residential, commerdal and industrial areas plamied for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) Design Considerations Designing New Installations The foUo-wing methods to reduce excessive irrigation runoff should be considered, and incorporated and implemented where determined applicable and feasible by the Peraiittee: • Employ rain-triggered shutoff de-vi<«s to prevent irrigation after precipitation. • Design irrigation sjTstems to each landscape area's spedfic water requirements. • Include design featuring flow reducers or shutoff valves triggered by a pressure drop to control water loss in the event of broken sprinkler heads or lines. • Implement landscape plans consistent with County or City water conservation resolutions, which may include provision of water sensors, programmable irrigation times (for short cycles), etc. January 2003 California Stormwater BMP Handbook New Development and Redevelopment vmw.cabmphandboote.com 1 of 2 SD-12 Efficient Irrigation • Design timing and application methods of irrigation water to minimize the ranoff of excess irrigation water into the storm -water drainage system. • Group plants with similar water requirements in order to reduce excess irrigation mnoff and promote surface filtration. Choose plants with low irrigation requirements (for example, native or drouglit 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 mnoff InstalUng appropriate plant materials for tlie location, in accordance with amount of sunUght and dimate, and use native plant materials where possible and/or as recommended by the landscape architect Leaving a vegetative barrier along the property bomidary and interior watercourses, to act as a pollutant filter, where appropriate and feasible Choosing plants that minimize or eUminate the use of fertilizer or pesticides to sustain growth • Employ other comparable, equally effective methods to reduce irrigation water runoff. Redeveloping Existing Installations Variousjurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases iu gross floor area and/or exterior constmction, and land disturbing activities -with stmctural 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 foUowed. 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 Coimty, 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 Febraary 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Trash Storage Areas SD-32 Design Objectives Description Trash storage areas are areas where a trash receptacle (s) are Maximize Infiltration located for use as a repository for solid wastes. Stonnwater Prowle Retention ranoff from areas -vdiere trash is stored or disposed of can be Runoff polluted. In addition, loose trash and debris can be easily transported by water or wind into nearby storm drain inlets, ^'"'""'^ Impen/ious Land channels, and/or creeks. Waste handling operations that may be ^ sources of stormwater pollution indude dumpsters, litter control, °^ In^Pfoper and waste piles. Approach This fact sheet contains details on the specific measures required to prevent or reduce pollutants in stomi-water mnoff associated •with trash storage and Iiandling. Preventative measures mcluding enclosures, containment stractures, and impervious pavements to mitigate spills, should be used to reduce the likelihood of contamination. Materials 0 Contain Poiiutants Collect and Convey Suitable Applications Appropriate appUcations include residential, a>mmercial 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 govemed by Building and Fire Codes, and by current local ageiwy ordinances and zoning requirements. The design criteria described in this fact sheet are meant to enhance and be consistent witli these code and ordinance requirements. Hazardous waste should be handled in accordance with legal requirements established in Title 22, CaUfomia Code of Regulation. Wastes from commerdal and industrial sites are typically hauled by dther public or commerdal carriers that may have design or access requirements for waste storage areas. The design criteria in this fad 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 foUowing structural or treatment control BMPs: • Design trash container areas so that drainage from adjoming roofs and pavement is diverted aromid the area(s) to avoid ran-on. This might include banning or grading the waste handling area to prevent mn-on of stomiwater. • Make sure trash container areas are screened or waUed to prevent off-site transport of trash. January 2003 California Stormwater BMP Handbook 1 of 2 New Development and Redevelopment www.cabmphandbooks.com SD-32 Trash Storage Areas • Use Uned bins or dumpsters to reduce leaking of liquid -waste. • Provide roofs, a-wnings, or attached Uds on aU trash containers to minimize direct predpitation and prevent rainfall from entering containers. • Pave trash storage areas wifli an impervious surface to mitigate spills. • Do not locate storm drains in immediate vidnity of the trash storage area. • Post signs on aU dumpsters informing users tiiat hazardous materials are not to be disposed of therein. Redeveloping lasting Installations Variousjurisdictional 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 constmction, and land disturbing activities with stmctural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas mtended for redevelopment. If tiie definition applies, tiie steps outlined under "designing new installations" above should be followed. Additional Information Maintenance Considerations The integrity of stmctural elements tliat are subject to dainage (i.e., screens, covers, and signs) must be maintained by the owner/operator. Maintenance agreements between the local agency and the owner/operator maybe required. Some agendes will require maintenance deed restrictions to be recorded of the property titie. 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 Stomiwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storin Water Mitigation Plan (SUSMP) for San Diego Coimty, Port of San Diego, aud Cities in San Diego County, Febraary 14, 2002. Model Water QuaUty Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the In«>rporated Cities of Orange County, Draft Febraary 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 Califomia Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmpharKltfoote.com Vegetated Buffer Strip TC-31 Design Considerations • Tributary Area • Slope • Water Availability • Aesthetics Description Grassed buffer strips (vegetated filter strips, filter strips, and grassed filters) are vegetated surfaces that are designed to treat sh^t flow from adjacent surfaces. Filter strips function by slowing ranoff velodties and aUowing sediment and other poUutants to settle and by pro-viding some infiltration into underlying soils. Filter strips were originally used as an agricultural treatment practice and have more recentfy evolved into an urban practice. With proper design and maintenance, filter strips can provide relatively high poUutant removal. In addition, the public views them as landscaped amenities and not as storm-water infrastructure. Consequently, there is little resistance to their use. California Experience Caltrans constmcted and monitored three vegetated buffer strips in southern CaUfomia and is currently evaluating their perfomiance at eight additional sites statewide. These strips were generaUy effedive in reducing the volume and mass of poiiutants in mnoff. Even in the areas where the amiual rainfaU -was only about lo inches/yr, the vegetation did not require additional irrigation. One factor that strongly affected performance was the presence of large numbers of gophers at most ofthe southern CaUfomia sites. The gophers created earthen mounds, destroyed vegetation, and generally reduced the effectiveness of tiie controls for TSS reduction. Advantages • Buffers require minimal maintenance activity (generally just erosion prevention and mo-wing). • If properly designed, vegetated, and operated, buffer strips can provide reUable -water quaUty benefits in conjunction -with high aesthetic appeal. Targeted Constituents 0 Sediment 0 Nutrients 0 Trash 0 Bacteria 0 Oil and Grease lies Legend pianov^ EfhoUveness) • Low • High • Medium January 2003 California Stonnwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 1 of 8 TC-31 Vegetated Buffer Strip • Flow characteristics and vegetation type and density can be closely controlled to maximize BMP effectiveness. • Roadside shoulders act as effective buffer strips -when slope and length meet criteria described below. Limitations • May not be appropriate for industrial sites or locations where spiUs may occur. • Buffer strips cannot treat a very large drainage area. • A thick vegetative cover is needed for these practices to fundion properly. • Buffer or vegetative filter length must be adequate and flow charaderistics acceptable or water quality perfomiance can be severely limited. • Vegetative buffers may not pro-vide treatment for dissolved constituents except to the extent that flows across the vegetated surface are infiltrated into the soil profile. • Tliis technology does not pro-vide significant attenuation of the increased volume and flow rate of ranoff during intense rain events. Design and Sizing Guidelines • Maximum length (in the direction of flow towards the buffer) of the tributary area should be 60 feet. • Slopes should not exceed 15%. • Minimum length (in direction of flow) is 15 feet. • Width should be the same as the tributary area. • Eitiier grass or a diverse selection of other low growing, drought tolerant, native vegetation should be spedfied. Vegetation whose growing season corresponds to the wet season is preferred. Construction/Inspecfion Considcratioiis • Indude directions in tiie spedfications for use of appropriate fertiUzer and soil amendments based on soil properties detennined througli testing and compared to the needs ofthe vegetation requirements. • InstaU strips at the time of the year when there is a reasonable chance of successful establishment without irrigation; however, it is recognized that rainfaU in a given year may not be sufficient and temporary irrigation may be required. • If sod tiles must be used, they should be placed so tliat there are no gaps between the tiles; stagger tiie ends ofthe tiiles to prevent the fonnation of channels along the strip. • Use a roller on the sod to ensure that no air pockets forai between the sod and the soil. 2 of 8 Califomia Stormwater BMP Handtook January 2003 New Development and Redevelopment wwfw.cabmphandboote.com Vegetated Buffer Strip TC-31 • Where seeds are used, erosion controls wiU be necessary to protect seeds for at least 75 days after the first rainfall of the season. Performance Vegetated buffer strips tend to pro-vide somewhat better treatment of stormwater ranoff tlian swales and have fewer tendendes for channeUzation or erosion. Table 1 documents the pollutant remo-val observed in a recent study by Caltrans (2002) based on three sites in southern CaUfomia. The column labeled "Significance" is the probability that the mean influent and effluent EMCs are not significantiy different based on an analysis of variance. The removal of sediment and dissolved metals was comparable to that observed in mudi more complex controls. Reduction in nitrogen was not significant and all ofthe sites exported phosphoras for tiie entire study period. Tiiis may iiave been the r^ult of using salt grass, a warm weather species that is dormant during the wet season, and which leaches phosphoras when domiant. Another Caltrans study (unpublished) of vegetated highway shoulders as buffer strips also found substantial reductions often -within a very short distance of the edge of pavement. Figure 1 presents a box and whisker plot of the concentrations of TSS in highway runoff after traveling various distances (shown in meters) througli a vegetated filter strip with a slope of about 10%. One can see that the TSS median concentration readies an irreducible minimum concentration of about 20 mg/L-within 5 meters ofthe pavement edge. Table 1 Pollutant Reduction in a Vegetated Buffer Strip Mean EMC _ ^ Removal Significauce Influent (mg/L) Effluent (mg/L) % P TSS 119 31 74 <0.000 NO3-N 0.67 0.58 13 0.367 TKN-N 2.50 2.10 16 0.542 Total 3-17 2.68 15 - DissohredP 0.15 0.46 -206 0.047 Total P 0.42 0.62 -52 0.035 Total Cu 0.058 0.009 84 <0.000 Total Pb 0.046 0.006 88 <0.000 Total Zn 0.245 0.055 78 <o.ooo Dissolved Cu 0.029 0.007 77 0.004 Dissolved Pb 0.004 0,002 66 0.006 Dissolved Zn 0.099 0.035 65 <0.000 January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 3 of 8 TC-31 Vegetated Buffer Strip 100 - 90 - 80- 70- 60- O co' 50- OD 40 -H 40 - 30 - 20 - 10 - 0 - length Filter strips also exhibit good removal of litter and other floatables because fhe -water depth in tiiese systems is weU below the vegetation heiglit and consequently these materials are not easily transported through them. Unfortunately littie attenuation of peak ranoff rates and volumes (particularly for larger events) is normaUy observed, depending on the soil properties. Therefore it may be pradent to foUow the strips with another practice than can reduce flooding and chamiel erosion downstream. Siting Criteria The use of buffer strips is limited to gentiy sloping areas where tiie vegetative cover is robust and diffuse, and -vrfiere shallow flow characteristics are possible. Tlie practical water quality benefits can be effectively eliminated witii the occurrence of significant erosion or when flow concentration occurs across the vegetated surface. Slopes should not exceed 15 percent or be less tlian 1 percent. The vegetative surface should extend across tiie fiiU -widtii of tiie area being drained. The upstream boundary of the filter should be located contiguous to tiie developed area. Use of a level spreading device (vegetated berm, sawtooth concrete border, rock trench, etc) to fadUtate overland sheet flow is not normaUy recoinmended because of maintenance considerations and the potential for standing water. Filter strips are appiicable in most regions, but are restricted in some situations because th^r consume a large amount of space relative to other practices. Filter strips are best suited to treating runoff from roads and highways, roof downspouts, smaU parking lots, and pervious surfaces. They are also ideal components of the "outer zone" ofa stream buffer or as prefreatment to a stractural practice. In arid areas, however, the cost of irrigating fhe grass on tiie practice will most likely outweigh its water quaUty benefits, although aesthetic considerations may be sufficient to overcome tiiis constraint. FUter strips are generally impractical in ultra-urban areas where Uttie pervious surface exists. Some cold water spedes, such as trout, are sensitive to changes in temperature. While some treatment practices, such as wet ponds, can warm stormwater substantiaUy, filter strips do not 4 of 8 Califomia Stormwater BMP Handbook New Deveiopment and Redevelopment wvm.cabmphandboote.com January 2003 Vegetated Buffer Strip TC-31 are not expected to increase stomiwater temperatures. Thus, these practices are good for protection of cold-water streams. Filter strips should be separated from the ground water by between 2 and 4 ft to prevent contamination and to ensure tiiat the filter strip does not remain wet between storms. Additional Design Guidelines Filter strips appear to be a minimal design pradice because tiiey are basically no more than a grassed siope. In general the slope of the strip shouid not exceed i5fc% and tiie strip should be at ieast 15 feet long to pro-vide water quality treatment. Both the top and toe ofthe slope should be as flat as possible to encourage sheet flow and prevent erosion. The top ofthe strip should be instaUed 2-5 inches below tiie adjacent pavement, so that vegetation and sediment accumulation at the edge of the strip does not prevent ranoff from entering. A major question that remains unresolved is how large the drainage area to a strip can be. Research has conclusively demonstrated that these are effective on roadside shoulders, where the contributing area is about twice the buffer area. They liave also been instaUed on the perimeter of large parking lots where they performed fairly effedively; iiowever much lower slopes may be needed to provide adequate water quaUty treatment. The filter area should be densely vegetated with a mix of erosion-resistant plant spedes that effectively bind the sofl. Native or adapted grasses, shmbs, and trees are preferred because they generally require iess fertilizer and are more drought resistant than exotic plants. Runoff flow velodties should not exceed about 1 ips across the vegetated surface. For engineered vegetative strips, the fadlity surface should be graded flat prior to placement of vegetation. Initial establishment of vegetation requires attentive care including appropriate watering, fertiUzation, and prevention of excessive flow across the facility until vegetation completely covers the area and is weU established. Use of a permanent irrigation system may help provide maximal water quality performance. In cold cUmates, filter strips provide a convenient area for snow storage and treatment. If used for this purpose, vegetation in the filter strip should be salt-tolerant (e.g., creeping bentgrass), and a maintenance schedule should include the removal of sand built up at tiie bottom oftiie slope. In arid or semi-arid dimates, designers should spedfy drought-tolerant grasses to minimize irrigation requirements. Maintenance Filter strips require mainly vegetation management; therefore Uttie special training is needed for maintenance crews. Typical maintenance activities and frequencies include: • Inspect strips at least twice annually for erosion or damage to vegetation, preferably at the end of the wet season to schedule summer maintenance and before major faU mn-off to be sure the strip is ready for winter. However, additional inspection after periods of hea-vy ran- off is most desirable. Tlie strip should be checked for debris and litter and areas of sediment accumulation. • Recent research on biofiltration swales, but likely applicable to strips (ColweU et al., 2000), indicates that grass height and mowing frequency have littie impact on poUutant removai; January 2003 California Stormwater BMP Handbook 5 of 8 New Development and Redevelopment www.cabmphandbooks.com TC-31 Vegetated Buffer Strip consequently, mowing may oniy be necessary once or twice a year for safety and aesthetics or to suppress weeds and woody vegetation. • Trash tends to accumulate in strip areas, particularly along higiiways. The need for litter removal should be determined tiirough periodic inspection but litter should always be removed prior to mowing. • Regularly inspect vegetated buffer strips for pools of standing water. Vegetated buffer strips can become a nuisance due to mosquito breeding in level spreaders (unless designed to dewater completely in 48-72 hours), in pools of standing water if obstmctions develop (e.g. debris accumulation, invasive vegetation), and/or if proper drainage slopes are not implemented and mauitained. Cost Construction Cosf Little data is available on the actual constmction costs of filter strips. One rough estimate can be the cost of seed or sod, which is approximately 30<t per ft^ for seed or 70<|; per ft= for sod. This amounts to between $13,000 and $30,000 per acre of filter strip. This cost is relatively high compared with other treatment practices. However, the grassed area used as a filter strip may have been seeded or sodded even if it were not used for treatment. In these cases, tiie only additional cost is the design. Typical maintenance costs are about $35o/acre/year (adapted from SWRPC, 1991)- This cost is relatively inexpensive and, again, might overlap with regular landscape maintenance costs. The true cost of filter strips is the land they consume. In some situations this land is available as wasted space beyond back yards or adjacent to roadsides, but this practice is cost-prohibitive when land prices are liigh and land could l>e used for other purposes. Maintenance Cost Maintenance of vegetated buffer strips consists mainly of vegetation management (mowing, irrigation if needed, weeding) and Utter removal. Consequently the costs are quite variable depending on the frequency ofthese activities and the local labor rate. References and Sources of Additional Information Caltrans, 2002, BMP Retrofit Pilot Program Proposed Final Report, Rpt. CTSW-RT-01-050, CaUfomia Dept. of Transportation, Sacramento, CA Center for Watershed Protection (CWP). 1996. Design of Stormwater Filtering Systems. Prepared for Chesapeake Research Consortium, Solomons, MD, and EPA Region V, Chicago, IL. Desbonette, A., P. Pogue, V. Lee, and N. Wolff. 1994. Vegetated Buffers in the Coastal Zone: A Summary Review and Bibliography. Coastal Resources Center. University of Rhode Island, Kingston, RI. Magette, W., R. Brinsfield, R. Palmer and J. Wood. 1989. Nutrient and Sediment Removal by Vegetated Filter Strips. Transactions of the American Society of Agricultural Engineers 32(2): 663-667. 6 of 8 Califomia Stormwater BMP Handtook January 2003 New Development and Redevelopment www.cabmphandboote.com Vegetated Buffer Strip TC-31 Metzger, M. E., D. F. Messer, C. L. Bdtia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side Of Stormwater Runoff Management: Disease Vectors Assodated With Stractural BMPs. Stormwater 3(2): 24-39. Southeastern Wisconsin Regional Planning Commission (SWRPC). 1991. Costs of Urban Nonpoint Source Water Pollution Control Measures. Technical report no. 31. Southeastern Wisconsin Regional Planning Commission, Waukesha, WI. Yu, S., S. Bames and V Gerde. 1993. Testing of Best Management Practices for Controlling Highway Runoff. FHWA/VA 93-R16. Virginia Transportation Research Coundl, CharlottesviUe, VA. Information Resources Center for Watershed Protection (CWP). 1997. Stomnvater BMP Design Supplement for Cold Climates. Prepared for U.S. Environmental Protection Agency Office of Wetlands, Oceans and Watersheds. Washington, DC. Maryland Department ofthe Environment (MDE). 2000. Maryland Stormwater Design Manual. http://'vvww.mde.state.md.us/eiivironment/wma/storniwatermanual. Accessed May 22, 2001. January 2003 Califomia Stormwater BMP Handbook 7 of 8 New Development and Redevelopment www.cabmphandbooks.com TC-31 Vegetated Buffer Strip < . 1" —.—yi :^ T r ^ — ^ PttvcmcDt Ares iilUiilUiUiiiUiUil Level Spraxfcr caibKlded oBbt^ modslar {NHWi N(ile:>fottoScafe 8 of 8 California Stormwater BMP Handlsook New Development arid Redevelopment vmw.cabmphandboote.com January 2003 I I I i I \ HI i 1 (llllll I / ! 11 .1 /, Nnm- EXISTING BLUFF EDGE MLL RECEDE J-^tosiMB Bi^FT^ AT A RATE OF 0.53' PER YEAR WITHOUT —^ EXISVNG RIP RAP TO PROTECT BLUFF BLUFF-.. CBOE .'A WW./ / jyI''' /////' y; ~ JN, t \0>«* 1 / / 7 \ J EXISTING RESIDENCE SCALE 1" = 20' * GRASS SHALL BE CAREX SISSA OR EOUIVALENT AS SPECIFIED BY LANDSCAPE ARCHITECT. GRASS SHALL BE MAINTAINED AS NEEDED TO ENSURE PERFORMANCE OF SWALE 0 VEGETA TED BUEEER STRIP TC-31 LEGEND: Hofman Planning & Engineering 5900 Pasteur Court, Ste 150 Carlsbad, CA 92008 (760) 438-1465 wvvw.hofmanplanning.com STORMWATER MANAGEMENT PLAN JOSEPH P. COH AH R.C.E. C5887J EXP. 06-30-07 DATE DATE JULY 6, 2007 JOB NO. ATTACHMENT NO. 8