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Home My WebLink AboutCT 04-10A; POINSETTIA PLACE; STORM WATER MANAGEMENT PLAN; DWG 469-5A; 2011-06-14.. - - - - - -- • ------------------- STORM WATER MANAGEMENT PLAN FOR POINSETTIA PLACE SWMP 10-14 June 14, 2011 Prepared for: Sierra Linda Development 2834 La Mirada Drive, Suite E Vista, CA 92081 111111[ [ X 1 J I lt~J I 11 l'i iH 1. \ li, if~) Civil Engineering O Hydrology O Hydraulics O Sedimentation P .0. Box 9496 Rancho Santa Fe, CA 92067 (858) 692-0760 +c. ,. -~-Lt ,.. A (.__ \ .:. J -\,.., ' - "' 0 z ~ 0 w ::c: 0 z c( _; CL ------ ------.. ------ - - --.. ---------- 1.0 1.1 1.2 1.3 2.0 2.1 2.1.1 2.1.2 3.0 3.1 3.2 4.0 4.1 4.2 4.3 5.0 6.0 -TABLE OF CONTENTS - Introduction ....................................................................................................................... 1 Project Description ............................................................................................................ 2 Site Map ............................................................................................................................ 2 Constraints and Opportunities ........................................................................................... 2 Water Quality Environment .............................................................................................. 3 Beneficial Uses ................................................................................................................. 3 Inland Surface Waters ....................................................................................................... 3 Groundwater ..................................................................................................................... 4 Pollutants and Conditions of Concern ............................................................................. .4 Pollutants from Project Area ............................................................................................. 4 Pollutants of Concern in Receiving Waters ...................................................................... 5 Permanent Storm Water Best Management Practices ...................................................... 5 Standard Site Design BMPs .............................................................................................. 6 Source Control BMPs ....................................................................................................... 7 Low Impact Design BMPs ................................................................................................ 9 Storm Water BMP Maintenance ..................................................................................... 10 Summary/Conclusions .................................................................................................... 11 7 .0 Certifications ................................................................................................................... 12 Storm Water Standards Questionnaire E-34 Low Impact Development Analysis Worksheet APPENDIX A. BMP Reference Materials MAP POCKET Poinsettia Place Site Map and LID Design BMP Exhibit BMP Site Plan ---------------------- .. --------• -• -• 1.0 INTRODUCTION This Storm Water Management Plan (SWMP) addresses water quality requirements associated with final engineering for the Poinsettia Place project located south of Cassia Road between Poinsettia Lane and Kalmia Circle in the city of Carlsbad. A preliminary SWMP was prepared for the tentative map on April 29th, 2004 by Hunsaker & Associates, San Diego, Inc. This final SWMP follows the criteria outlined in city of Carlsbad's March 24, 2010, Standard Urban Storm Water Management Plan (SUSMP). The recent SUSMP contains additional requirements that were not present when the preliminary SWMP was prepared. According to the City's Storm Water Standards Questionnaire E-34 (attached following this report text), the development is in the following priority project categories: housing subdivision, parking lot, streets, and 1-acre of disturbance. The project obtained a construction permit and started construction prior to January 14, 2011. As a result, the project has lawful prior approval and is not subject to the interim hydromodification criteria pursuant to Order No. R9-2007-0001 and the January 14, 2011 SUSMP. The SUSMP outlines the SWMP objectives, which are to identify site opportunities and constraints, identify pollutants and conditions of concern, follow low impact development design objectives, describe best management practices (BMPs ), and outline maintenance requirements. BMPs will be utilized to the maximum extent practicable to provide a long-term solution for addressing runoff water quality. BMPs were selected that meet the current regulations and also fit within the already entitled project. CITY OF OCEANSIDE ,.8 PACIFIC OCEAN 1 -------• -• -• ------ - - - ------• -• -• 1.1 Project Description The Poinsettia Place project is a proposed residential subdivision that will consist of attached single-family units along with associated driveways, sidewalks, landscaping, drainage facilities, and outdoor recreation areas. The development will be constructed within an undeveloped 18.97 acre parcel on the south side of Cassia Road east of Poinsettia Lane. Adjacent uses consist of residential development and agriculture. Under pre-project conditions, the site is mostly pervious and covered with vegetation. The area along Cassia Road was previously mass-graded by adjacent development and slopes gradually towards the west. The southern portion of the site rises up forming a small, natural, undisturbed hillside. Off-site runoff from a small drainage area (approximately 5 acres according to the drainage study prepared for the tentative map) flows westerly towards the development footprint. The combined on-and off-site runoff tributary to the future development footprint enters an existing detention basin near Poinsettia Lane. The runoff is then generally conveyed in a southerly direction and ultimately flows into Batiquitos Lagoon . Under post-project conditions, an underground storm drain and associated drainage facilities will convey the on-and off-site runoff from east to west through the site. The storm drain will outlet into a proposed detention basin that will replace the existing detention basin. The runoff exiting the proposed detention basin will continue to be conveyed southerly towards Batiquitos Lagoon. 1.2 Site Map A Site Map is included following this report text. The site map includes color coded drainage management areas used for the Low Impact Development design. 1.3 Constraints and Opportunities As shown on the site map, the development is being clustered along Cassia Road in order to preserve an undisturbed natural area along the southern boundary of the site. The clustering provides the ability to preserve over 60 percent of the site in its natural state. The development will consist of attached single-family residences surrounded by gently sloping landscape areas and shared driveways. The landscape areas provide opportunities to treat runoff through contact and bio-filtration by vegetation. A single, primary drive will provide access to the shared driveways. Pervious (aka, permeable) pavers will be installed where the primary driveway intersects with the series of shared driveways. Pervious pavers will also be used near the site entrance. A bioretention basin is proposed at the downstream (west) end of the site. All of the on-site runoff within the development footprint will enter either the pervious pavers or the bioretention basin. 2 - ---------------• -- - --------- --• -• 2.0 WATER QUALITY ENVIRONMENT 2.1 Beneficial Uses The beneficial uses for the hydrologic unit are included in Tables 1 and 2. These tables were obtained from the Water Quality Control Plan for the San Diego Basin (9). The following contains definitions of the beneficial uses in the tables: MUN -Municipal and Domestic Supply: Includes uses of water for community, military, or individual water supply systems including, but not limited to, drinking water supply. AGR -Agricultural Supply (AGR): Includes uses of water for farming, horticulture, or ranching including, but not limited to, irrigation, stock watering, or support of vegetation for range grazing. RECl -Contact Recreation: Includes uses of water for recreational activities involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, swimming, wading, water-skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs. REC2 -Non-Contact Recreation: Includes the uses of water for recreational involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, picnicking, sunbathing, hiking, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities. 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. WILD -Wildlife Habitat: Includes uses of water that support terrestrial ecosystems including, but not limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife, (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlife water and food sources. 2.1.1 Inland Surface Waters Inland surface waters for the San Marcos Hydrologic Area have the beneficial uses shown in Table 1: 3 - -------.. -• ------ - - - --------• -• .. • Table 1. Beneficial Uses for Inland Surface Waters Hydro logic Unit s::: -N (.) .... ..s::: ~ 0 Code ;::l .... "O 0 ~ (.) (.) l:ll) 00 0 (1) (1) ::E s::: .... .... co < -~ 0 ..... ~ ~ ~ 904.51 + • • • + Exempted by the Regional Board from the municipal use designation. • Existing Beneficial Use 2.1.2 Groundwater ~ :9 :9 s::: (1) ~ ta 0 ~ c:i.. ~ u ~ U'.l • • Groundwater beneficial uses for the Batiquitos Hydrologic Subarea are shown in Table 2: Table 2. Beneficial Uses for Groundwater Hydrologic Unit Code s::: 5h (.) ..s::: .... ;::l "O 8 00 ~ ::E < s::: .... 0 -~ ..... 904.51 0 0 0 0 Potential Beneficial Use 3.0 POLLUTANTS AND CONDITIONS OF CONCERN 3.1 Pollutants from Project Area The project is located within the Batiquitos Hydrologic Subarea (904.51) of the San Marcos Hydrologic Area (904.50), which is within the Carlsbad Hydrologic Unit (904.00). The total drainage area of the hydro logic unit is approximately 210 square miles. Runoff from portions of the hydro logic subarea ultimately drain to Batiquitos Lagoon, which is south of the project site. All of the project runoff will ultimately enter Batiquitos Lagoon. The project site represents less than one percent of the overall watershed. The following table lists pollutants of concern that are anticipated or can potentially exist at proposed priority project development sites. The pollutants are from the city of Carlsbad's SUSMP. The project falls within the attached residential development, parking lots, and streets, highways & freeways priority project categories (highlighted yellow in the table). All of the listed pollutants are either anticipated or can potentially exist at the developed site. 4 --- - -- - - - ... .. --- ·• ---... Table 3. Priority Project Pollutants Priority Project Sediments Categories Detached Residential Development Attached Residential Development Commercial Development > one acre Heavy Industry Automotive Repair Shops Restaurants Hillside Development >5,000 ft2 Parking Lots Retail Gasoline Outlets Streets, Highways& Freeways X = Anticipated P = Potential X X p(l) X X p(l) X Heavy Nutrients Metals X X p(l) X X X p(l) X X p(l) X Organic Compounds p(2) X x\•JPJ X x<4) (I) A potential pollutant if landscaping exists on-site Trash & Debris X X X X X X X X X X (2) A potential pollutant if the project includes uncovered parking areas (3) A potential pollutant ifland use involves food or animal waste products ( 4) Including petroleum hydrocarbons (5) Including solvents 3.2 Pollutants of Concern in Receiving Waters Oxygen Oil Bacteria Demanding & & Pesticides Substances Grease Viruses X X X X p(l) p(2) p(ll X p(5) X p(3) p(5) X X X X X X X X X p(l) X p(l) X X p(5) X According to the 2006 303(d) list approved by the State Water Resources Control Board (and by the US EPA in June 2007), the receiving water body closest to the project vicinity, Batiquitos Lagoon, is not 303( d) listed and is not subject to total maximum daily loads (TMDLs). Therefore, the project does not generate pollutants of concern in the receiving waters . 4.0 PERMANENT STORM WATER BEST MANAGEMENT PRACTICES To address water quality for the project, best management practices (BMPs) will be implemented. The following discusses the Standard Site Design, Source Control, and Low Impact Development design BMPs for the project. 5 -- ----------.. - -- - - ---- --- - 4.1 Standard Site Design BMPs The city of Carlsbad's standard objectives are required for all projects. The Poinsettia Place project will accomplish these goals through the following BMPs, which are from the Carlsbad SUSMP: Standard Stormwater Requirements Minimize Impervious Surfaces. The project will include pervious surfaces (landscaping within the development area and no disturbance along the southerly portion of the site. which is over 60 percent of the site). The project will also use pervious (permeable) pavers along some traffic areas. Disconnect Discharges. Roof drains will discharge to adjacent landscape areas, where feasible. Pervious pavers will be used where the shared driveways intersect the primary access drive. Walkways between the residential units will drain over adjacent landscape areas before being collected by catch basins. Conserve Natural Areas. The southern portion of the site, which covers over 60 percent of the site including a natural hillside, will not be disturbed. The development is being clustered along a mass graded area along Cassia Road. Stenciling Inlets and Signage. The curb inlets along the main drive will be stenciled with prohibitive language such as "No Dumping - I live downstream" or approved similar. Landscape Design. A landscape plan will be prepared that uses drought-tolerant species in accordance with the City's landscape manual. Native trees and shrubs will be preserved over the majority of the parcel in order to maximize canopy interception and promote water conservation. The project will only use water as needed to support the landscaping. Water Efficient Irrigation. The irrigation systems will be designed to each landscaped areas water requirements to avoid over irrigation. Rain shutoff devices will be used to prevent irrigation after rain events. Protect Slopes And Channels. The grading design does not include large slopes or channels. The design will prevent runoff from flowing uncontrolled over the tops of manufactured slopes. The proposed slopes will be landscaped. Riprap energy dissipaters will be used at storm drain outfalls. Vegetate slopes with native or drought tolerant vegetation. Native and drought tolerant vegetation will be used to the extent allowed by the resource agencies. Trash Receptacles. Each residence will have personal, covered trash receptacles. Material Storage Areas. The project does not propose outdoor material storage areas. Any required material storage shall be kept under cover. 6 - - ---- ---.. - -.. - - -- -• - -----• 4.2 Source Control BMPs Source control BMPs will consist of measures to prevent polluted runoff. The following addresses the source control BMPs from the Carlsbad SUSMP: Potential Source of Runoff Pollutants On-site storm drain inlets Need for future indoor & structural pest control Landscape/Outdoor Pesticide Use Permanent Source Control BMPs Mark all inlets with "No Dumping - I live downstream" Buildings shall be designed to avoid openings that would encourage entry of pests. Final landscape plans will accomplish all of the following. • Preserve existing native trees, shrubs, and ground cover to the maximum extent possible. • Design landscaping to minimize irrigation and runoff, to promote surface infiltration where appropriate, and to minimize the use of fertilizers and pesticides that can contribute to stormwater pollution. • Where landscaped areas can retain or detain stormwater, specify plants that are tolerant of saturated soil 7 Operational Source Control BMPs • Maintain and periodically repaint inlet markings • Provide stormwater pollution information to owners, lessees, and operators (Fact sheet SC- 44 from the CASQA Stormwater Quality Handbook at www .cabmphandbooks.com) • Owner/lessee agreements shall state "Tenant shall not allow anyone to discharge anything to storm drains or to store or deposit material.s so as to create a potential discharge to storm drains . Integrated Pest Management ( e.g., the EPA' s Citizen 's Guide to Pest Control and Pesticide Safety) information shall be provided to owners, lessees, and operators. Maintain landscaping using minimum or no pesticides. See applicable operational BMPs in Fact Sheet SC-41, "Building and Grounds Maintenance," and TC- 30, "Vegetated Swale," in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Integrated Pest Management ( e.g., the EPA' s Citizen's Guide to Pest Control and Pesticide Safety) information shall be provided to owners, lessees, and operators. -- -conditions. -• Where surface runoff will -flow along or be directed to landscape areas ( e.g., from -roof drains and walkways), -vegetation and grass will be designed to function as -vegetated bio-swales. -• Consider using pest-resistant -plants, especially adjacent to -hardscape. -• To ensure successful establishment, select plants -appropriate to site soils, -slopes, climate, sun, wind, rain, land use, air movement, -ecological consistency, and -plant interactions .. Vehicle and The CC&Rs will prohibit car equipment cleaning washing at the site. The HOA will be responsible for enforcing this requirement. -Vehicle/Equipment The CC&Rs will prohibit Repair and repair and maintenance -Maintenance activities in areas exposed to precipitation and storm flows. The HOA will be responsible -for enforcing this requirement. Roofing, gutters, and The architectural design will trim avoid roofing, gutters, and trim -made of copper or other unprotected metals that may leach into runoff. -Plazas, sidewalks, Plazas, sidewalks, and parking lots and parking lots. shall be swept regularly to prevent -the accumulation of litter and -debris. Debris from pressure washing shall be collected to -prevent entry into the storm drain -system. Wash water containing any cleaning agent or degreaser -shall be collected and discharged -to the sanitary sewer and not discharged to a storm drain. -• -8 • ---------------------- - ------------ 4.3 Low Impact Development Design BMPs. A preliminary SWMP was prepared by Hunsaker and Associates on April 29t\ 2004 for the tentative map. The SWMP proposed a single Vortechs Treatment Unit for treating all of the site runoff. The City's current SUSMP requires an integrated LID strategy for managing runoff, which extends beyond the treatment provided by the Vortechs Treatment Unit. The integrated LID outlines four strategies: 1. Optimize the site layout by preserving natural drainage features and designing buildings and circulation to minimize the amount of roofs and paving. 2. Use pervious surfaces such as turf, gravel, or pervious pavement-or use surfaces that retain rainfall. All drainage from these surfaces is considered to be "self-retained". 3. Disperse runoff from impervious surfaces on to adjacent pervious surfaces (e.g., direct a roof downspout to disperse runoff onto a lawn). 4. Drain impervious surfaces to engineered Integrated Management Practices (IMPs), such as bioretention facilities, planter boxes, cisterns, or dry wells. IMPs infiltrate runoff to groundwater and/or percolate runoff through engineered soil and allow it to drain away slowly. The project design is in compliance with these strategies. The site layout has been designed along Cassia Road in an area that was previously mass graded by adjacent development. Over 60 percent of the lot is being preserved in open space including the majority of the natural, undisturbed portions of the site. The residential units will have up to three floors to obtain the desired square footage, while minimizing the building footprints. A single drive ( and connected shared driveways) will provide access to the units. Runoff from the roofs will either flow towards pervious landscape areas or onto a shared driveway. Pervious (permeable) pavers will treat storm runoff from the roof and shared driveways. The pervious pavers and tributary drainage areas (yellow hatching) are shown on the "Site Map and LID Design" exhibit in the map pocket. Design details are shown on the BMP Exhibit in the map pocket. The SUSMP defines the pervious pavers as self-retaining areas capable of infiltrating 1 inch of rainfall that do not require additional treatment. A bioretention basin will treat the portion of on-site runoff that is not self-retained in the pervious pavers. There are upstream areas that are tributary to the development. These include natural areas adjacent to, but outside, the development footprint that will be conveyed through the site by drainage facilities. The SUSMP defines these as self-treating areas that do not require further treatment. Therefore, the bioretention basin excludes treatment for these upstream areas. A bioretention basin was selected because it provides high to medium removal effectiveness for the pollutants generated by the project (see Table 3). The bioretention basin was sized 9 -----------• -.. ------ - - ------------• using the LID procedure from the City's SUSMP (see the worksheet following this report text). The development site was divided into the following drainage management areas (DMA): • Streets and their adjacent curb, gutter, and sidewalks • Interior walkways • Roofs (roofs tributary to the pervious pavers were excluded) • Landscape areas The area of each DMA was digitized and multiplied by the appropriate runoff factor. The first three categories were assigned a runoff factor of 1.0 and the landscape areas were assigned a runoff factor of 0.1. The total product of the DMA area and runoff factor was multiplied by 0.04 to obtain the minimum bio-retention area (5,558 square feet). The bioretention area shown on the exhibit in the map pocket covers 5,795 square feet. Therefore, it meets the bioretention requirement. The BMP Exhibit in the map provides details for the Bioretention area. 5.0 STORM WATER BMP MAINTENANCE The developer will be responsible for funding and implementing the operations and maintenance of the project BMPs. Provisions will be made to transfer operations and maintenance to the new owner in the event of a change in ownership. The homeowner's association will ultimately be responsible for ongoing operations and maintenance. The following describes the specific BMP maintenance. Pervious (Permeable) Pavers After installation, inspect pavers once a month for 4 to 6 months. After this period inspection can occur annually, particularly after there has been heavy rain or storms, for this is the time when the drainage voids can become clogged with organic debris. Sweep and/or vacuum the permeable surface every 3 months. Street sweepers that have a vacuum and brushes can be used. High pressure hosing shall be performed after sweeping/vacuuming. Voids should be kept filled with aggregate. Replace damaged pavers, as needed. Bioretention basin The drainage outlet from the basin shall be inspected prior to the rainy season and after large storm events. Debris, sediment, and other obstructions shall be removed immediately from the outlet. The habitat shall also be inspected annually and replanted as needed to maintain an adequate cover. Landscaping and Vegetated Swales Maintenance will be performed by landscaping personnel. The vegetation will be maintained and inspected on a weekly basis by landscape maintenance staff and will be replaced or replanted, as necessary, to maintain a dense, healthy cover. The vegetation will also be inspected prior to storm events. Maintenance shall include periodic mowing, weed control, irrigation, reseeding/replanting of bare areas, and clearing of debris. A design grass height of 6 inches is recommended. Grass clippings shall not be left in grass swales. The private 10 - -.. -- - - - - - -- ·- --- drainage system will shall be kept clear of debris and inspect prior to and during the rainy season to ensure it is free-flowing. Efficient Irrigation The landscaping personnel shall inspect and maintain the irrigation system on a regular basis. This will occur during the routine maintenance activities. All valves, heads, shutoff devices, lines, etc. shall be kept in a properly functioning condition. Any defective parts shall be replaced immediately. The irrigation system shall be adjusted to prevent excessive runoff from landscape areas. The irrigation schedule shall be adjusted based on seasonal needs. Inlet Stenciling Any stenciling shall be inspected at the beginning and end of each rainy season and repaired or replaced, as needed . Hazardous Wastes Suspected hazardous wastes will be analyzed to determine disposal options. Hazardous materials are not expected to be generated on-site; however, if discovered, hazardous materials will be handled and disposed of according to local, state, and federal regulations. A solid or liquid waste is considered a hazardous waste if it exceeds the criteria listed in the California Code of Federal Regulations, Title 22, Article 11 (State of California, 1985). 6.0 SUMMARY/CONCLUSIONS This SWMP has been prepared in accordance with the city of Carlsbad's March 24, 2010, Standard Urban Storm Water Management Plan (SUSMP). This SWMP has evaluated and addressed potential pollutants associated with the Poinsettia Place residential development and its effects on water quality. The preliminary SWMP approved during the tentative map process proposed a Vortechs Treatment Unit to treat the site runoff. Under the recent regulations, this type of treatment BMP is not sufficient for the pollutants associated with the governing priority project categories. As a result, the latest LID design criteria was used and BMPs were selected that meet the current SUSMP, while remaining compatible within the entitled project. The following table summarizes the primary treatment and LID BMPs for the project. Type Description Ownership Bioretention Basin has been sized per LID guidelines and will be Homeowner's Basin installed at the downstream receiving end of the site. Association Pervious Pervious pavers will act as self-retaining areas that will Homeowner's Pavers treat runoff from some rooftops and shared driveways. Association Vegetated Landscape areas will include vegetated swales where Homeowner's Swales feasible to treat turnoff from roof drains, walkways, and Association other areas. Summary of Treatment and LID BMPs 11 -------------------- - - - --.. -... ---- • 7.0 CERTIFICATIONS Preparer Certification The selection. sizing. and preliminary design of stonnwater treatment control measures in this plan meet the requirements of Regional Water Quality Control Board Order R9-2007- 000 I and subsequent amendments. Owner Certification I certify that as owner of the property described herein, I have read and understand the requirements of this Stonn Water Management Plan (SWMP) and that I am responsible for ensuring that all stonnwater treatment measures described within said SWMP will be properly implemented. monitored. and maintained. I will execute necessary agreements for BMP maintenance. I will be responsible for operation and maintenance :zilities until that responsibility is fonnally transferred. LL &-d 515/ti ~ Date 12 ------- ------------ ----------• - • -• -• «14'" ~ CITY OF CARLSBAD INSTRUCTIONS: STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Engineering Department 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov To address post-development pollutants that may be generated from development projects, the City requires that new development and significant redevelopment priority projects incorporate Permanent Storm Water Best Management Practices (BM P's) into the project design per the City's Standard Urban Stormwater Management Plan (SUSMP). Initially this questionnaire must be completed by the applicant in advance of submitting for a development application (subdivision, discretionary permits and/or construction permits). The results of the questionnaire determine the level of storm water standards that must be applied to a proposed development or redevelopment project. Depending on the outcome, your project will either be subject to 'Standard Stormwater Requirements' or be subject additional criteria called 'Priority Development Project Requirements'. Many aspects of project site design are dependent upon the storm water standards applied to a project. Applicant responses to the questionnaire represent an initial assessment of the proposed project conditions and impacts. City staff has responsibility for making the final assessment after submission of the development application. If staff determines that the questionnaire was incorrectly filled out and is subject to more stringent storm water standards than initially assessed by the applicant, this will result in the return of the development application as incomplete. In this case, please make the changes to the questionnaire and resubmit to the City. If applicants are unsure about the meaning of a question or need help in determining how to respond to one or more of the questions, they are advised to seek assistance from Land Development Engineering staff. A separate completed and signed questionnaire must be submitted for each new development application submission. Only one completed and signed questionnaire is required when multiple development applications for the same project are submitted concurrently. In addition to this questionnaire, applicants for construction permits must also complete, sign and submit a Project Threat Assessment Form to address construction aspects of the project. Please answer the questions below, follow the instructions and sign the form at the end. I 1. Is your project a significant redevelopment? DEFINITION: Significant redevelopment is defined as the creation, addition or replacement of at least 5,000 square feet of impervious surface on an already existing developed site. Significant redevelopment includes, but is not limited to: the expansion of a building footprint; addition to or replacement of a structure; structural development including an increase in gross floor area and/or exterior construction remodeling; replacement of an impervious surface that is not part of a routine maintenance activity; and land disturbing activities related with structural or impervious surfaces. Replacement of impervious surfaces includes any activity that is not part of a routine maintenance activity where impervious material(s) are removed, exposing underlying soil during construction. If your project IS considered significant redevelopment, then please skip Section 1 and proceed with Section 2 . If your project IS NOT considered significant redevelopment, then please proceed to Section 1. E-34 Page 1 of 3 REV 3/23/10 -----------------• -• ---------.. --- ~ «~ ~ CITY OF CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Engineering Department 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov JSECTION 1 NEW DEVELOPMENT PRIORITY PROJECT TYPE YES NO Does you project meet one or more of the following criteria: 1. Housing subdivisions of 10 or more dwelling units. Examples: single family homes, multi-family homes, condominium and apartments X 2. Commercial -greater than 1-acre. Any development other than heavy industry or residential. Examples: hospitals; laboratories and other medical facilities; educational institutions; recreational facilities; municipal facilities; commercial X nurseries; multi-apartment buildings; car wash facilities; mini-malls and other business complexes; shopping malls; hotels; office buildinos; public warehouses; automotive dealerships; airfields; and other lioht industrial facilities. 3. Heavy Industrial I Industry-greater than 1 acre. Examples: manufacturing plants, food processing plants, metal working facilities, printing plants, and fleet storage areas (bus, truck, etc.). X 4. Automotive repair shop. A facility categorized in any one of Standard Industrial Classification (SIC) codes 5013, X 5014, 5541, 7532-7534, and 7536-7539 5. Restaurants. Any facility that sells prepared foods and drinks for consumption, including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption (SIC code 5812), where the land area for development is greater than 5,000 square feet. Restaurants where land development is less than 5,000 X square feet shall meet all SUSMP requirements except for structural treatment BMP and numeric sizing criteria requirements and hydromodification requirements. 6. Hillside development. Any development that creates 5,000 square feet of impervious surface and is located in an area with known erosive soil conditions, where the development will grade on any natural slope that is twenty-five X percent (25%) or oreater. 7. Environmentally Sensitive Area (ESAJ1. All development located within or directly adjacent2 to or discharging directly3 to an ESA (where discharges from the development or redevelopment will enter receiving waters within the X ESA), which either creates 2,500 square feet of impervious surface on a proposed project site or increases the area of imperviousness of a proposed project site to 10% or more of its naturally occurrino condition. 8. Parking lot. Area of 5,000 square feet or more, or with 15 or more parking spaces, and potentially exposed to urban X runoff 9. Streets, roads, highways. and freeways. Any paved surface that is 5,000 square feet or greater used for the transportation of automobiles, trucks, motorcycles, and other vehicles X 10. Retail Gasoline Outlets. Serving more than 100 vehicles per day and greater than 5,000 square feet X 11. Coastal Development Zone. Any project located within 200 feet of the Pacific Ocean and (1) creates more than 2500 square feet of impermeable surface or (2) increases impermeable surface on property by more than 10%. X 12. More than 1-acre of disturbance. Project results in the disturbance of more than considered a Pollutant-generating Development Project4. 1-acre or more of land and is X .. 1 Environmentally Sens1t1ve Areas include but are not limited to all Clean Water Act Section 303(d) 1mpa1red water bodies; areas designated as Areas of Special Biological Significance by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); water bodies designated with the RARE beneficial use by the State Water Resources Control Board (Water Quality Control Plan for the San Diego Basin (1994) and amendments); areas designated as preserves or their equivalent under the Multi Species Conservation Program within the Cities and County of San Diego; and any other equivalent environmentally sensitive areas which have been identified by the Copermittees. 2 "Directly adjacent" means situated within 200 feel of the Environmentally Sensitive Area. 3 "Discharging directly to" means outflow from a drainage conveyance system that is composed entirely of flows from the subject development or redevelopment site, and not commingled with flow from adjacent lands. 4 Pollutant-generating Development Projects are those projects that generate pollutants at levels greater than background levels. In general, these include all projects that contribute to an exceedance to an impaired water body or which create new impervious surfaces greater than 5000 square feet and/or introduce new landscaping areas that require routine use of fertilizers and pesticides. In most cases linear pathway projects that are for infrequent vehicle use, such as emergency or maintenance access, or for pedestrian or bicycle use, are not considered Pollutant-generating Development Projects if they are built with pervious surfaces or if they sheet flow to surroundin ervious surfaces. Section 1 Results: .If you answered YES to ANY of the questions above your project is subject to Priority Development Project requirements. Please check the "meets PRIORITY DEVELOPMENT PROJECT requirements" box in Section 3. A Storm Water Management Plan, prepared in accordance with City Storm Water Standards, must be submitted at time of application. If you answered NO to ALL of the questions above, then your project is subject to Standard Stormwater Requirements. Please check the "does • not meet PDP requirements" box in Section 3. ---E-34 Page 2 of 3 REV 3/23/10 • -------• -• ---• -• -• ----- «~ ~ CITY OF CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Engineering Department 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov SECTION 2 SIGNIFICANT REDEVELOPMENT N/A Complete the questions below regarding your redevelopment project: YES NO 1. Project results in the disturbance of more than 1-acre or more of land and is considered a Pollutant-generating Development Project (see definition in Section 1 ). If you answered NO, please proceed to question 2 . If you answered YES, then you ARE a significant redevelopment and you ARE subject to PRIORITY DEVELOPMENT PROJECT requirements. Please check the "meets PRIORITY DEVELOPMENT PROJECT requirements" box in Section 3 below. 2. Is the project redeveloping an existing priority project type? (Priority projects are defined in Section 1) If you answered YES, please proceed to question 3. If you answered NO, then you ARE NOT a significant redevelopment and your project is subject to STANDARD STORMWATER REQUIREMENTS. Please check the "does not meet PDP requirements" box in Section 3 below . 3. Is the project solely limited to just one of the following: a. Trenching and resurfacing associated with utility work? b . Resurfacing and reconfiguring existing surface parking lots? C. New sidewalk construction, pedestrian ramps, or bike lane on public and/or private existing roads? d. Replacement of existing damaged pavement? If you answered NO to ALL of the questions, then proceed to question 4 . If you answered YES to ANY of the questions then you ARE NOT a significant redevelopment and your project is subject to Standard Stormwater Requirements. Please check the "does not meet PDP requirements" box in Section 3 below. 4. Will your redevelopment project create, replace, or add at least 5,000 square feet of impervious surfaces on an existing development or, be located within 200 feet of the Pacific Ocean and ( 1 )create more than 2500 square feet of impermeable surface or (2) increases impermeable surface on the propertv by more than 10%? If you answered YES, you ARE a significant redevelopment, and you ARE subject to PRIORITY DEVELOPMENT PROJECT requirements. Please check the "meets PRIORITY DEVELOPMENT PROJECT requirements" box in Section 3 below. If you answered NO, then you ARE NOT a significant redevelopment and your project is subject to STANDARD STORMWATER REQUIREMENTS. Please check the "does not meet PDP requirements" box in Section 3 below. • SECTION 3 -Questionnaire Results: ----------- - My project meets PRIORITY DEVELOPMENT PROJECT (PDP) requirements and must comply with additional stormwater criteria per the SUSMP and must prepare a Storm Water Management Plan for submittal at time of application. D My project does not meet PDP requirements and must only comply with STANDARD STORMWATER REQUIREMENTS per the SUSMP. Applicant Information and Signature Box This Box for Cffy Use Only Address: P. Q. Box 9496 Assessor's Parcel Number(s): Rancho Santa Fe, CA 92067 215-020-23 City Concurrence: I YES I NO I I Applicant Name: Applicant Title: By: Wayne Chang Principal Date: Date: October 27, 2010 Project ID: E-34 Page 3 of 3 REV 3/23/10 11 II II II I I 11 II II 11 II 11 11 II 11 11 I I I I I LOW IMPACT DEVELOPMENT ANALYSIS WORKSHEEl (see work map for OMA delineations) OMA Name Street + adjacent curb, gutter, and sidewalk Interior walkways Roofs Landscape areas Total OMA Area, sf 51,127 12,652 63,086 120,926 247,791 Post-project surface type Concrete/ Asphalt Concrete Roof Material Vegetation Bioretention area= sizing factor x (Total Area x Runoff Factor)= 0.04 x 138,958 = 5,558 sf (sizing factor= 0.04 for bioretention) OMA Runoff Factor 1.0 1.0 1.0 0.1 Area x Runoff Factor, sf 51,127 12,652 63,086 12,093 138,958 APPENDIX A BMP Reference Materials ... - ... • - -- - Building & Grounds Maintenance SC-41 Description Stormwater runoff from building and grounds maintenance activities can be contaminated with toxic hydrocarbons in solvents, fertilizers 1:md pesticides, suspended solids, heavy metals, abnormal pH, and oils mid greases. Utilizing the protocols in this fact sheet vvill prevent or reduce the discharge of pollutants to stormwater from building and grounds maintenance activities by vvashing and cleaning up with as little water as possible, following good lm1dscape management practices, preventing and cleaning up spills immediately, keeping debris from entering the storm drains, and maintaining the stormwater collection system. Approach Reduce potential for pollutant dischmge through source control pollution prevention and BI\iIP implementation. Successful implementation depends on effective training of employees on applicable BMPs and general pollution prevention strategies and objectives. Pollution Prevention • Switch to non-toxic chemicals for maintenance when possible. • Choose cleaning agents that can be recycled. • Encourage proper lmvn mmiagement and landscaping, including use of native vegetation. January 2003 California Stormwater BMP Handbook Industrial and Commercial www .cabmphandbooks.com Objectives • Cover • Contain • Educate • Reduce/Minimize • Product Substitution Targeted Constituents Sediment Nutrients Trash Metals Bacteria Oil and Grease Organics ,I ,I ,I ,I .A, S QA 1 of 5 -- --------.. ------ SC-41 Building & Grounds Maintenance • Encourage use of Integrated Pest Management techniques for pest control. • Encourage proper onsite recycling of yard trimmings. • Recycle residual paints, solvents, lumber, and other material as much as possible. Suggested Protocols Pressure Washing of Buildings, Rooftops, and Other Large Objects • In situations where soaps or detergents are used and the surrounding area is paved, pressure washers must use a water collection device that enables collection of wash water and associated solids. A sump pump, wet vacuum or similarly effective device must be used to collect the runoff and loose materials. The collected runoff and solids must be disposed of properly . • If soaps or detergents are not used, and the surrounding area is paved, wash runoff does not have to be collected but must be screened. Pressure washers must use filter fabric or some other type of screen on the ground and/or in the catch basin to trap the particles in wash water runoff. • If you are pressure washing on a grassed area (with or without soap), runoff must be dispersed as sheet flow as much as possible, rather than as a concentrated stream. The wash runoff must remain on the grass and not drain to pavement. Landscaping Activities • Dispose of grass clippings, leaves, sticks, or other collected vegetation as garbage, or by composting. Do not dispose of collected vegetation into waterways or storm drainage systems. -• Use mulch or other erosion control measures on exposed soils. -- "- - "---- ----- Building Repair, Remodeling, and Construction • Do not dump any toxic substance or liquid waste on the pavement, the ground, or toward a storm drain. • • • • Use ground or drop cloths underneath outdoor painting, scraping, and sandblasting work, and properly dispose of collected material daily. Use a ground cloth or oversized tub for activities such as paint mixing and tool cleaning . Clean paintbrushes and tools covered with water-based paints in sinks connected to sanitary sewers or in portable containers that can be dumped into a sanitary sewer drain. Brushes and tools covered with non-water-based paints, finishes, or other materials must be cleaned in a manner that enables collection of used solvents (e.g., paint thinner, turpentine, etc.) for recycling or proper disposal. Use a storm drain cover, filter fabric, or similarly effective runoff control mechanism if dust, grit, wash water, or other pollutants may escape the work area and enter a catch basin. This is particularly necessary on rainy days. The containment device(s) must be in place at the beginning of the work day, and accumulated dirty runoff and solids must be collected and disposed of before removing the containment device(s) at the end of the work day. 2 of s California Stormwater BMP Handbook Industrial and Commercial January 2003 www .cabmphandbooks.com ---------• ----- ---- - - ------ • ------ Building & Grounds Maintenance SC-41 • If you need to de-water an excavation site, you may need to filter the water before discharging to a catch basin or off-site. If directed off-site, you should direct the water through hay bales and filter fabric or use other sediment filters or traps. • Store toxic material under cover during precipitation events and when not in use. A cover would include tarps or other temporary cover material. Mowing, Trimming, and Planting • Dispose of leaves, sticks, or other collected vegetation as garbage, by composting or at a permitted landfill. Do not dispose of collected vegetation into waterways or storm drainage systems. • Use mulch or other erosion control measures when soils are exposed. • Place temporarily stockpiled material away from watercourses and drain inlets, and berm or cover stockpiles to prevent material releases to the storm drain system. • Consider an alternative approach when bailing out muddy water: do not put it in the storm drain; pour over landscaped areas. • Use hand weeding where practical. Fertilizer and Pesticide Management • Follow all federal, state, and local laws and regulations governing the use, storage, and disposal of fertilizers and pesticides and training of applicators and pest control advisors. • Use less toxic pesticides that will do the job when applicable. Avoid use of copper-based pesticides if possible. • Do not use pesticides if rain is expected. • Do not mix or prepare pesticides for application near storm drains. • Use the minimum amount needed for the job. • Calibrate fertilizer distributors to avoid excessive application. • Employ techniques to minimize off-target application (e.g., spray drift) of pesticides, including consideration of alternative application techniques. • Apply pesticides only when wind speeds are low. • Fertilizers should be worked into the soil rather than dumped or broadcast onto the surface. • Irrigate slowly to prevent runoff and then only as much as is needed. • Clean pavement and sidewalk if fertilizer is spilled on these surfaces before applying irrigation water. • Dispose of empty pesticide containers according to the instructions on the container label. January 2003 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com 3 of 5 --- ---- • -• -------- - - --.. -----• ---- SC-41 Building & Grounds Maintenance • Use up the pesticides. Rinse containers, and use rinse water as product. Dispose of unused pesticide as hazardous waste. • Implement storage requirements for pesticide products with guidance from the local fire department and County Agricultural Commissioner. Provide secondary containment for pesticides. Inspection • Inspect irrigation system periodically to ensure that the right amount of water is being applied and that excessive runoff is not occurring. Minimize excess watering and repair leaks in the irrigation system as soon as they are observed. Training • Educate and train employees on pesticide use and in pesticide application techniques to prevent pollution. • Train employees and contractors in proper techniques for spill containment and cleanup. • Be sure the frequency of training takes into account the complexity of the operations and the nature of the staff. Spill Response and Prevention • Keep your Spill Prevention Control and Countermeasure (SPCC) Plan up-to-date. • Place a stockpile of spill cleanup materials, such as brooms, dustpans, and vacuum sweepers (if desired) near the storage area where it will be readily accessible. • Have employees trained in spill containment and cleanup present during the loading/unloading of dangerous wastes, liquid chemicals, or other materials. • Familiarize employees with the Spill Prevention Control and Countermeasure Plan. • Clean up spills immediately. Other Considerations Alternative pest/weed controls may not be available, suitable, or effective in many cases. Requirements Costs • Cost will vary depending on the type and size of facility. • Overall costs should be low in comparison to other BMPs. Maintenance Sweep paved areas regularly to collect loose particles. Wipe up spills with rags and other absorbent material immediately, do not hose down the area to a storm drain. 4 of 5 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com January 2003 -----• -• -• ---• -------- - --- - - - --- Building & Grounds Maintenance SC-41 Supplemental Information Further Detail of the BMP Fire Sprinkler Line Flushing Building fire sprinkler line flushing may be a source of non-stormwater runoff pollution. The water entering the system is usually potable water, though in some areas it may be non-potable reclaimed wastewater. There are subsequent factors that may drastically reduce the quality of the water in such systems. Black iron pipe is usually used since it is cheaper than potable piping, but it is subject to rusting and results in lower quality water. Initially, the black iron pipe has an oil coating to protect it from rusting between manufacture and installation; this will contaminate the water from the first flush but not from subsequent flushes. Nitrates, poly- phosphates and other corrosion inhibitors, as well as fire suppressants and antifreeze may be added to the sprinkler water system. Water generally remains in the sprinkler system a long time (typically a year) and between flushes may accumulate iron, manganese, lead, copper, nickel, and zinc. The water generally becomes anmdc and contains living and dead bacteria and breakdown products from chlorination. This may result in a significant BOD problem and the water often smells. Consequently dispose fire sprinkler line flush water into the sanitary sewer. Do not allow discharge to storm drain or infiltration due to potential high levels of pollutants in fire sprinkler line water. References and Resources California's Nonpoint Source Program Plan http://www.swrcb.ca.gov/nps/index.html Clark County Storm Water Pollution Control Manual http://www.co.dark. wa. us/pubworks/bmpman.pdf King County Storm Water Pollution Control Manual htU>://dnr.metrokc.gov/wlr/dss/spcm.htm Mobile Cleaners Pilot Program: Final Report. 1997. Bay Area Stormwater Management Agencies Association (BASMAA). http://www.basmaa.org/ Pollution from Surface Cleaning Folder. 1996. Bay Area Stormwater Management Agencies Association (BASMAA). http://www.basmaa.org/ Santa Clara Valley Urban Runoff Pollution Prevention Program http://www.scvurppp.org The Storm Water Managers Resource Center http://www.stormwatercenter.net/ January 2003 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com 5 of 5 Drainage System Maintenance SC-44 Description As a consequence of its function, the stormwater conveyance system collects and tnmsports urban nmoff and stonnwater that may contain ce1tain pollutants. The protocols in this fact sheet are intended to reduce pollutm1ts reaching receiving waters through proper conveyance system operation and maintenance. Approach Poll utio11 Preve11 tio11 Maintain catch basins, stornnvater inlets, and other stormwater conveyance structures on a regular basis to remove pollutm1ts, reduce high pollutant concentrations during the first flush of stonns, prevent clogging of the downstremn convey mice system, restore catch basins' sediment trapping capacity, and ensure the system functions properly hydraulically to avoid flooding. Suggested Protocols Catch Basins/Inlet Str11ct11re.s • Staff should regularl:v inspect facilities to ensure compliance with the follovving: Immediate repair of any deterioration threatening structural integrity. Clem1ing before the swnp is 4090 full. Catch basins should be clem1ed as frequently as needed to meet this standard. Stenciling of c ate h basins and inlets ( see SC:34 \V aste Handling and Disposal). January 2003 California Stormwater BMP Handbook Industrial and Commercial www .cabmphandbooks.com Objectives • Cover • Contain • Educate • Reduce/Minimize Targeted Constituents Sediment Nutrients Trash ~ Metals Bacteria ~ Oil and Grease Organics ~ SQA C.Nfoml• S1Drmw.dllr QuaNty Al90datlon 1 of 6 - ... ----- - .... - SC-44 Drainage System Maintenance • Clean catch basins, storm drain inlets, and other conveyance structures before the wet season to remove sediments and debris accumulated during the summer . • Conduct inspections more frequently during the wet season for problem areas where sediment or trash accumulates more often. Clean and repair as needed. • Keep accurate logs of the number of catch basins cleaned. • Store wastes collected from cleaning activities of the drainage system in appropriate containers or temporary storage sites in a manner that prevents discharge to the storm drain. • Dewater the wastes if necessary with outflow into the sanitary sewer if permitted. Water should be treated with an appropriate filtering device prior to discharge to the sanitary sewer. If discharge to the sanitary sewer is not allowed, water should be pumped or vacuumed to a tank and properly disposed. Do not dewater near a storm drain or stream. Storm Drain Conveyance System • Locate reaches of storm drain with deposit problems and develop a flushing schedule that keeps the pipe clear of excessive buildup . • Collect and pump flushed effluent to the sanitary sewer for treatment whenever possible. Pump Stations • Clean all storm drain pump stations prior to the wet season to remove silt and trash. • Do not allow discharge to reach the storm drain system when cleaning a storm drain pump station or other facility. • Conduct routine maintenance at each pump station. • Inspect, clean, and repair as necessary all outlet structures prior to the wet season. Open Channel • Modify storm channel characteristics to improve channel hydraulics, increase pollutant """ removals, and enhance channel/creek aesthetic and habitat value. -- ------ • Conduct channel modification/improvement in accordance with existing laws. Any person, government agency, or public utility proposing an activity that will change the natural (emphasis added) state of any river, stream, or lake in California, must enter into a Steam or Lake Alteration Agreement with the Department of Fish and Game. The developer-applicant should also contact local governments (city, county, special districts), other state agencies (SWRCB, RWQCB, Department of Forestry, Department of Water Resources), and Federal Corps of Engineers and USFWS. Illicit Connections and Discharges • Look for evidence of illegal discharges or illicit connections during routine maintenance of conveyance system and drainage structures: 2 of 6 Is there evidence of spills such as paints, discoloring, etc? California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com January 2003 .. -- -- -------- - - - .... - ------ Drainage System Maintenance SC-44 Are there any odors associated with the drainage system? Record locations of apparent illegal discharges/illicit connections? Track flows back to potential dischargers and conduct aboveground inspections. This can be done through visual inspection of upgradient manholes or alternate techniques including zinc chloride smoke testing, fluorometric dye testing, physical inspection testing, or television camera inspection. Eliminate the discharge once the origin of flow is established. • Stencil or demarcate storm drains, where applicable, to prevent illegal disposal of pollutants. Storm drain inlets should have messages such as "Dump No Waste Drains to Stream" stenciled next to them to warn against ignorant or intentional dumping of pollutants into the storm drainage system. • Refer to fact sheet SC-10 Non-Stormwater Discharges. Illegal Dumping • Inspect and clean up hot spots and other storm drainage areas regularly where illegal dumping and disposal occurs. • Establish a system for tracking incidents. The system should be designed to identify the following: Illegal dumping hot spots Types and quantities (in some cases) of wastes Patterns in time of occurrence (time of day/night, month, or year) Mode of dumping (abandoned containers, "midnight dumping'" from moving vehicles, direct dumping of materials, accidents/ spills) Responsible parties • Post "No Dumping" signs in problem areas with a phone number for reporting dumping and disposal. Signs should also indicate fines and penalties for illegal dumping. • Refer to fact sheet SC-10 Non-Stormwater Discharges. Training • Train crews in proper maintenance activities, including record keeping and disposal. • Allow only properly trained individuals to handle hazardous materials/wastes. • Have staff involved in detection and removal of illicit connections trained in the following: OSHA-required Health and Safety Training (29 CFR 1910.120) plus annual refresher training (as needed). January 2003 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com 3 of 6 - ---- ------------ - - ----------• -• SC-44 Drainage System Maintenance OSHA Confined Space Entry training (Cal-OSHA Confined Space, Title 8 and Federal OSHA 29 CFR 1910.146). Procedural training (field screening, sampling, smoke/dye testing, TV inspection). Spill Response and Prevention • Investigate all reports of spills, leaks, and/or illegal dumping promptly. • Clean up all spills and leaks using "dry" methods (with absorbent materials and/or rags) or dig up, remove, and properly dispose of contaminated soil. • Refer to fact sheet SC-11 Spill Prevention, Control, and Cleanup. Other Considerations (Limitations and Regulations) • Clean-up activities may create a slight disturbance for local aquatic species. Access to items and material on private property may be limited. Trade-offs may exist between channel hydraulics and water quality /riparian habitat. If storm channels or basins are recognized as wetlands, many activities, including maintenance, may be subject to regulation and permitting. • Storm drain flushing is most effective in small diameter pipes (36-inch diameter pipe or less, depending on water supply and sediment collection capacity). Other considerations associated with storm drain flushing may include the availability of a water source, finding a downstream area to collect sediments, liquid/sediment disposal, and prohibition against disposal of flushed effluent to sanitary sewer in some areas. • Regulations may include adoption of substantial penalties for illegal dumping and disposal. • Local municipal codes may include sections prohibiting discharge of soil, debris, refuse, hazardous wastes, and other pollutants into the storm drain system. Requirements Costs • An aggressive catch basin cleaning program could require a significant capital and O&M budget. • The elimination of illegal dumping is dependent on the availability, convenience, and cost of alternative means of disposal. The primary cost is for staff time. Cost depends on how aggressively a program is implemented. Other cost considerations for an illegal dumping program include: 4 of 6 Purchase and installation of signs. Rental of vehicle(s) to haul illegally-disposed items and material to landfills. Rental of heavy equipment to remove larger items (e.g., car bodies) from channels. Purchase of landfill space to dispose of illegally-dumped items and material. California Stormwater BMP Handbook Industrial and Commercial www .cabmphandbooks.com January 2003 ---- ------------• ---- - - ----------- Drainage System Maintenance SC-44 • Methods used for illicit connection detection (smoke testing, dye testing, visual inspection, and flow monitoring) can be costly and time-consuming. Site-specific factors, such as the level of impervious area, the density and ages of buildings, and type of land use will determine the level of investigation necessary. Maintenance • Two-person teams may be required to clean catch basins with vactor trucks. • Teams of at least two people plus administrative personnel are required to identify illicit discharges, depending on the complexity of the storm sewer system. • Arrangements must be made for proper disposal of collected wastes. • Technical staff are required to detect and investigate illegal dumping violations. Supplemental Information Further Detail of the BMP Storm Drain Flushing Flushing is a common maintenance activity used to improve pipe hydraulics and to remove pollutants in storm drainage systems. Flushing may be designed to hydraulically convey accumulated material to strategic locations, such as an open channel, another point where flushing will be initiated, or the sanitary sewer and the treatment facilities, thus preventing resuspension and overflow of a portion of the solids during storm events. Flushing prevents "plug flow" discharges of concentrated pollutant loadings and sediments. Deposits can hinder the designed conveyance capacity of the storm drain system and potentially cause backwater conditions in severe cases of clogging. Storm drain flushing usually takes place along segments of pipe with grades that are too flat to maintain adequate velocity to keep particles in suspension. An upstream manhole is selected to place an inflatable device that temporarily plugs the pipe. Further upstream, water is pumped into the line to create a flushing wave. When the upstream reach of pipe is sufficiently full to cause a flushing wave, the inflated device is rapidly deflated with the assistance of a vacuum pump, thereby releasing the backed up water and resulting in the cleaning of the storm drain segment. To further reduce impacts of stormwater pollution, a second inflatable device placed well downstream may be used to recollect the water after the force of the flushing wave has dissipated. A pump may then be used to transfer the water and accumulated material to the sanitary sewer for treatment. In some cases, an interceptor structure may be more practical or required to recollect the flushed waters. It has been found that cleansing efficiency of periodic flush waves is dependent upon flush volume, flush discharge rate, sewer slope, sewer length, sewer flow rate, sewer diameter, and population density. As a rule of thumb, the length of line to be flushed should not exceed 700 feet. At this maximum recommended length, the percent removal efficiency ranges between 65- 75 % for organics and 55-65% for dry weather grit/inorganic material. The percent removal efficiency drops rapidly beyond that. Water is commonly supplied by a water truck, but fire hydrants can also supply water. To make the best use of water, it is recommended that reclaimed water be used or that fire hydrant line flushing coincide with storm sewer flushing. January 2003 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com 5 of 6 ----- -------------.. ---- - -------- • -• SC-44 Drainage System Maintenance References and Resources California's Nonpoint Source Program Plan http://www.swrcb.ca.gov/nps/index.html Clark County Storm Water Pollution Control Manual http://www.co.dark. wa. us/pubworks/bmpman.pdf Ferguson, B.K. 1991. Urban Stream Reclamation, p. 324-322, Journal of Soil and Water Conservation. King County Storm Water Pollution Control Manual http://dnr.metrokc.gov/wlr/dss/spcm.htm Oregon Association of Clean Water Agencies. Oregon Municipal StormwaterToolbox for Maintenance Practices. June 1998. Santa Clara Valley Urban Runoff Pollution Prevention Program http://www.scvm:ppp.org The Storm Water Managers Resource Center http://www.stormwatercenter.net United States Environmental Protection Agency (USEPA). 2002. Pollution Prevention/Good Housekeeping for Municipal Operations Storm Drain System Cleaning. On line: http://www.epa.gov/npdes/menuofbmps/poll 16.htm 6 of 6 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com January 2003 Pervious Pavements Description SD-20 Design Objectives 0 Maximize Infiltration 0 Provide Retention 0 Slow Runoff @ Minimize Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey PerTious paving is used for light vehicle loading in parking areas. The term describes a system comprising a load-bearing, durable surface together vvith an underlying layered structure that temporarily stores water prior to infiltration or drainage to a controlled outlet. The surface can itself be porous such that water infiltrates across the entire surface of the material (e.g., grass and gravel surfaces, porous concrete and porous asphalt), or can be built up of impermeable blocks separated by spaces and joints, through which the water can drnin. This latter system is termed 'permeable' paving. Advantages of pervious pavements is that they reduce runoff volume \vhile providing treatment, and arc unobtrusive resulting in a high level of acceptability. Approach Attenuation of flow is provided by the storage ,,vithin the underlying structure or sub base, together with appropriate flow controls. An underlying geotextilc may permit grou ndwatcr recharge, thus contributing to the restoration of the natural water cycle. Alternatively, where infiltration is inappropriate ( e.g., if the gmundwater rnlnerabilily is high, or the soil lype is unsuitable), the surface can be constructed above an impermeable membrane. The system offers a valuable solution for draimge of spatially constrained urban areas. Significant attenuation and improvement in water quality can be achieved by permeable pavements, v,fochever method is used. The surface and subsurface infrastructure can remove both the soluble and fine particulate pollutants that occur within urban runoff. Roof waler can be piped into the storage area directly, adding arens from which the flmv can be attenuated. Also, within lined systems, there is the opportunity fcJr stored runoff to be piped out for reuse. Suitable Applications Residential, commercial and industrial applications are possible. The use of permeable pavement may be restricted in cold regions, arid regions or regions with high \',·ind erosion. There arc some specific disadvantages associated with permeable pavement, which are as li:>llows: January 2003 California Stormwater BMP Handbook New Development and Redevelopment www .cabmphandbooks.com ~ ASQ 1 of 10 ----------- ---• -• -• -------------• - • -• SD-20 Pervious Pavements • Permeable pavement can become clogged if improperly installed or maintained. However, this is countered by the ease with which small areas of paving can be cleaned or replaced when blocked or damaged. • Their application should be limited to highways with low traffic volumes, axle loads and speeds (less than 30 mph limit), car parking areas and other lightly trafficked or non- trafficked areas. Permeable surfaces are currently not considered suitable for adoptable roads due to the risks associated with failure on high speed roads, the safety implications of ponding, and disruption arising from reconstruction. • When using un-lined, infiltration systems, there is some risk of contaminating groundwater, depending on soil conditions and aquifer susceptibility. However, this risk is likely to be small because the areas drained tend to have inherently low pollutant loadings. • The use of permeable pavement is restricted to gentle slopes. • Porous block paving has a higher risk of abrasion and damage than solid blocks. Design Considerations Designing New Installations If the grades, subsoils, drainage characteristics, and groundwater conditions are suitable, permeable paving may be substituted for conventional pavement on parking areas, cul de sacs and other areas with light traffic. Slopes should be flat or very gentle. Scottish experience has shown that permeable paving systems can be installed in a wide range of ground conditions, and the flow attenuation performance is excellent even when the systems are lined . The suitability of a pervious system at a particular pavement site will, however, depend on the loading criteria required of the pavement. Where the system is to be used for infiltrating drainage waters into the ground, the vulnerability of local groundwater sources to pollution from the site should be low, and the seasonal high water table should be at least 4 feet below the surface. Ideally, the pervious surface should be horizontal in order to intercept local rainfall at source. On sloping sites, pervious surfaces may be terraced to accommodate differences in levels. Design Guidelines The design of each layer of the pavement must be determined by the likely traffic loadings and their required operational life. To provide satisfactory performance, the following criteria should be considered: • The subgrade should be able to sustain traffic loading without excessive deformation. • The granular capping and sub-base layers should give sufficient load-bearing to provide an adequate construction platform and base for the overlying pavement layers. • The pavement materials should not crack of suffer excessive rutting under the influence of traffic. This is controlled by the horizontal tensile stress at the base of these layers . 2 of 10 California Stormwater BMP Handbook New Development and Redevelopment www .ca bmphand boo ks .com January 2003 ... ... - -.. -- - - ... ---.. - - --.. Pervious Pavements SD-20 There is no current structural design method specifically for pervious pavements. Allowances should be considered the following factors in the design and specification of materials: • Pervious pavements use materials with high permeability and void space. All the current UK pavement design methods are based on the use of conventional materials that are dense and relatively impermeable. The stiffness of the materials must therefore be assessed. • Water is present within the construction and can soften and weaken materials, and this must be allowed for. • Existing design methods assume full friction between layers. Any geotextiles or geomembranes must be carefully specified to minimize loss of friction between layers. • Porous asphalt loses adhesion and becomes brittle as air passes through the voids. Its durability is therefore lower than conventional materials. The single sized grading of materials used means that care should be taken to ensure that loss of finer particles between unbound layers does not occur. Positioning a geotextile near the surface of the pervious construction should enable pollutants to be trapped and retained close to the surface of the construction. This has both advantages and disadvantages. The main disadvantage is that the filtering of sediments and their associated pollutants at this level may hamper percolation of waters and can eventually lead to surface ponding. One advantage is that even if eventual maintenance is required to reinstate infiltration, only a limited amount of the construction needs to be disturbed, since the sub-base below the geotextile is protected. In addition, the pollutant concentration at a high level in the structure allows for its release over time. It is slowly transported in the stormwater to lower levels where chemical and biological processes may be operating to retain or degrade pollutants. The design should ensure that sufficient void space exists for the storage of sediments to limit the period between remedial works. • Pervious pavements require a single size grading to give open voids. The choice of materials is therefore a compromise between stiffness, permeability and storage capacity. • Because the sub-base and capping will be in contact with water for a large part of the time, the strength and durability of the aggregate particles when saturated and subjected to wetting and drying should be assessed. • A uniformly graded single size material cannot be compacted and is liable to move when construction traffic passes over it. This effect can be reduced by the use of angular crushed rock material with a high surface friction . In pollution control terms, these layers represent the site oflong term chemical and biological pollutant retention and degradation processes. The construction materials should be selected, in addition to their structural strength properties, for their ability to sustain such processes. In general, this means that materials should create neutral or slightly alkaline conditions and they should provide favorable sites for colonization by microbial populations. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 3 of 10 --- SD-20 Pervious Pavements Construction/ Inspection Considerations • Permeable surfaces can be laid without cross-falls or longitudinal gradients. • The blocks should be lain level • They should not be used for storage of site materials, unless the surface is well protected from deposition of silt and other spillages. • The pavement should be constructed in a single operation, as one of the last items to be • built, on a development site. Landscape development should be completed before pavement construction to avoid contamination by silt or soil from this source. ---.. --.. -.. .... • Surfaces draining to the pavement should be stabilized before construction of the pavement. • Inappropriate construction equipment should be kept away from the pavement to prevent damage to the surface, sub-base or sub-grade . Maintenance Requirements The maintenance requirements of a pervious surface should be reviewed at the time of design and should be clearly specified. Maintenance is required to prevent clogging of the pervious surface. The factors to be considered when defining maintenance requirements must include: • Type of use • Ownership • Level of trafficking • The local environment and any contributing catchments Studies in the UK have shown satisfactory operation of porous pavement systems without maintenance for over 10 years and recent work by Imbe et al. at 9th ICUD, Portland, 2002 ... describes systems operating for over 20 years without maintenance. However, performance under such regimes could not be guaranteed, Table 1 shows typical recommended maintenance regimes: - -... - ------ 4 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 - - ---- -.. --·--- - - ----- ---------- Pervious Pavements SD-20 Table 1 Typical Recommended Maintenance Regimes Activity Schedule • Minimize use of salt or grit for de-icing • Keep landscaped areas well maintained Ongoing • Prevent soil being washed onto pavement • Vacuum clean surface using commercially available sweeping machines at the following times: -End of winter (April) 2/ 3 x per year -Mid-summer (July / August) -After Autumn leaf-fall (November) • Inspect outlets Annual • If routine cleaning does not restore infiltration rates, then reconstruction of part of the whole of a pervious surface may be required. • The surface area affected by hydraulic failure should be lifted for inspection of the internal materials to identify the location and As needed (infrequent) extent of the blockage. Maximum 15-20 years • Surface materials should be lifted and replaced after brush cleaning. Geotextiles may need complete replacement. • Sub-surface layers may need cleaning and replacing . • Removed silts may need to be disposed of as controlled waste . Permeable pavements are up to 25 % cheaper (or at least no more expensive than the traditional forms of pavement construction), when all construction and drainage costs are taken into account. (Accepting that the porous asphalt itself is a more expensive surfacing, the extra cost of which is offset by the savings in underground pipework etc.) (Niemczynowicz, et al., 1987) Table 1 gives US cost estimates for capital and maintenance costs of porous pavements (Landphair et al., 2000) Redeveloping Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of" redevelopment'' must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations'' above should be followed. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 5 of 10 - --.. - -------------------------• -- SD-20 Additional Information Cost Considerations Pervious Pavements Permeable pavements are up to 25 % cheaper (or at least no more expensive than the traditional forms of pavement construction), when all construction and drainage costs are taken into account. (Accepting that the porous asphalt itself is a more expensive surfacing, the extra cost of which is offset by the savings in underground pipework etc.) (Niemczynowicz, et al., 1987) Table 2 gives US cost estimates for capital and maintenance costs of porous pavements (Landphair et al., 2000) 6 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 11 It II II II I I I II II II II II II II 11 II 11 I Pervious Pavements Table 2 Engineer's Estimate for Porous Pavement 11, .. u-tt Price Cydell Qsul,1 Year AcnWS Grading SV $2.00 61>' PaYW'lg SV $19.00 212 E:iceavadotl CY $3.60 201 Flhrftbrle sv $1.15 700 s«ine FIii CV S16.00 201 Sand CY $7.00 100 Sight Wei EA $300.00 2 Seeding LF $0.05 6'4 Cnec:kDam CY $35.00 0 Totel Conelructlon CQets ConelnJction Coets Amortized w'8Yaara Item u-tt Pric, Cych!II QNM.1 v ... AcnWS Sweeping /JC, $2:50.00 6 1 Wastiing /JC, $2:50.00 6 1 ln$ptetlon t.M $20.00 5 5 Deep Clean /JC, $450.00 0.5 1 TotelAan•I Meil......_..~ J.anu ary 200 3 Porous Pavement Tetal q.J1111t.2 T4'1al Qsul,3 AcreWS AcnWS $1,.208 1209 s2,41e 1812 $4,028 424 se.056 636 $724 403 $1,451 '°' seo5 1400 $1,610 2000 $3,216 403 se,44e 604 $700 200 $1,400 300 $600 3 $900 4 $32 1288 $64 1932 so 0 so 0 $10,105 $19,ta $505 "" Annual Maintenance Exaense Tetal q.J1111t.l T4'1al QNM,3 AcreWS AcnWS $1,500 2 $3,000 3 $1,500 2 $3,000 3 $100 5 $100 5 $225 2 SAoO 3 '3,980 $7,792 California stormw ater B MP Ha, dbook New Development and Redevelopment w w w , cabrrp handbook:;:, com SD-20 Tetal q.J1111t..4 T4'1al Qsut.5 To1111 AcreWS Ac"WS $3,824 2419 $4,8,38 3020 $6,040 $12,084 848 $16,112 1oeo $20,140 $2,174 15W $2,902 1008 $3,629 $2,300 2800 $3,220 36()0 $4,140 $9,664 806 $12,"6 1008 S16.12e $2,100 400 s2.eoo 500 $3,500 $1,200 7 $2,100 7 $2,100 $97 2578 $129 3220 $161 $0 0 so 0 so $2'619 M,158 .... 7" St.Alt $2,008 $2,aG Tetal q.J1111t.4 T4'1al Qsut.5 To1111 AcreWS AcnWS $4,500 4 $6,000 5 $7,500 $4,500 4 $6,000 5 $7,500 $100 5 $100 5 $100 $675 3.9 $878 5 $1,125 s11.es1 $15-'83 $19,370 7 of 10 ------------------------ ---• -• -• -• -• SD-20 Pervious Pavements Other Resources Abbott C.L. and Camino-Mateos L. 2001. In situ performance monitoring of an infiltration drainage system and field testing of current design procedures. Journal CIWEM, 15(3), pp.198- 202. Construction Industry Research and Information Association (CIRIA). 2002. Source Control using Constructed Pervious Surfaces C582, London, SW1P 3AU. Construction Industry Research and Information Association (CIRIA). 2000. Sustainable urban drainage systems -design manual for Scotland and Northern Ireland Report C521, London, SW1P 3AU. Construction Industry Research and Information Association (CIRIA). 2000 C522 Sustainable urban drainage systems -design manual for England and Wales, London, SW1P 3AU. Construction Industry Research and Information Association (CIRIA). RP448 A1anual of good practice for the design, construction and maintenance of infiltration drainage systems for stormwater runoff control and disposal, London, SW1P 3AU. Dierkes C., Kuhlmann L., Kandasamy J. & Angelis G. Pollution Retention Capability and Maintenance of Permeable Pavements. Proc 9th International Conference on Urban Drainage, Portland Oregon, September 2002. · Hart P (2002) Permeable Paving as a Stormwater Source Control System. Paper presented at Scottish Hydraulics Study Group 14h Annual seminar, SUDS. 22 March 2002, Glasgow. Kobayashi M., 1999. Stormwater runoff control in Nagoya City. Proc. 8th Int. Conf. on Urban Storm Drainage, Sydney, Australia, pp.825-833. Landphair, H., McFalls, J., Thompson, D., 2000, Design Methods, Selection, and Cost Effectiveness of Stormwater Quality Structures, Texas Transportation Institute Research Report 1837-1, College Station, Texas. Legret M, Colandini V, Effects of a porous pavement with reservior strucutre on runoff water:water quality and the fate of heavy metals. Laboratoire Central Des Pants et Chaussesss Macdonald K. & Jefferies C. Performance Comparison of Porous Paved and Traditional Car Parks. Proc. First National Conference on Sustainable Drainage Systems, Coventry June 2001. Niemczynowicz J, Hogland W, 1987: Test of porous pavements performed in Lund, Sweden, in Topics in Drainage Hydraulics and Hydrology. BC. Yen (Ed.), pub. Int. Assoc. For Hydraulic Research, pp 19-80. Pratt C.J. SUSTAINABLE URBAN DRAINAGE -A Review of published material on the performance of various SUDS devices prepared for the UK Environment Agency. Coventry University, UK December 2001. Pratt C.J,, 1995. Infiltration drainage -case studies of UK practice. Project Report 8 of 10 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 ---------• ---------- --------• -• -• -• -• Pervious Pavements SD-20 22,Construction Industry Research and Information Association, London, SWtP 3AU; also known as National Rivers Authority R & D Note 485 Pratt. C. J., 1990. Permeable Pavements for Stormwater Quality Enhancement. In: Urban Stormwater Quality Enhancement -Source Control, retrofitting and combined sewer technology, Ed. H.C. Torno, ASCE, ISBN 087262 7594, pp. 131-155 Raimbault G., 1997 French Developments in Reservoir Structures Sustainable water resources I the 21st century. Malmo Sweden Schluter W. & Jefferies C. Monitoring the outflow from a Porous Car Park Proc. First National Conference on Sustainable Drainage Systems, Coventry June 2001. Wild, T.C., Jefferies, C., and D'Arcy, B.J. SUDS in Scotland -the Scottish SUDS database Report No SR(o2)09 Scotland and Northern Ireland Forum for Environmental Research, Edinburgh. In preparation August 2002. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 9 of 10 ---------• -• -• -• -• -------------• ---• -• SD-20 Pervious Pavements 10 of 10 Gedexlile t--'---·--·:...:;... _ _.__j Permeable , • • _,._, SIJb.base " 11 " " -·--------•Tofurther ,. I treatment Impermeable disposal Membrane or reuse la) PerviOU5 pavement used for •ttenuation · tr--,--· . · --:-~~1 · Overflow ' ~ ' ---------· ,, ! ' I · 'f' ____ : _____ .0 __ :'.:_ _ _J Permeable Geotexlile " " " • • Sub-base Infiltration (bl Pervious pavement used for infiltration Schematics of a Pervious Pavement System California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 Vegetated Swale , ... ,. r Description Vegetated swales are open, shallow channels ·with ,·egetation covering the side slopes and bottom that collect and slowly convey runoff flow to downstream discharge points. They arc designed to treat runoff through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Svvales can be natural or manmade. They trap particulate pollutants (suspended solids and trace metals), promote infiltration, and reduce the flow velocity of stormwater runoff. Vegetated swales can serve as part of a storm,,vater drainage system and can replace curbs, gutters and storm sewer systems. California Experience Caltrans constructed and monitored six ,·egctated swales in southern California. These swales were generally effective in reducing the volume and mass of pollutants in runoff. Even in the areas where the annual rainfall was only about 10 inches/)T, the vegetation did not require l.ldditiorrnl irrigl.ltion. One factor that strongly a ffectcd performance was the presence of large numbers of gophers at most of the sites. The gophers cm.ited earthen mounds, destroyed Yegetation, and generally reduced the effectiveness of the controls for TSS reduction. Advantages • If properly designed, vegetated, and operated, swalcs can serve as an aesthetic, potentially inexpensive urban development or roadway drainage corweyance measure with significant collateral water quality benefits. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www .cabm pha ndbooks. com TC-30 Design Considerations • Tributary Area • Area Required • Slope • Water Availability Targeted Constituents 0 Nutrients • 0 Trash • 0 Metals • 0 Bacteria • 0 Oil and Grease • 0 Organics • Legend (Removal Effectiveness) • Low • High • Medium ~ ASQ 1 of 13 ... - -.. - TC-30 Vegetated Swale • Roadside ditches should be regarded as significant potential swale/buffer strip sites and should be utilized for this purpose whenever possible. Limitations • Can be difficult to avoid channelization. • May not be appropriate for industrial sites or locations where spills may occur • Grassed swales cannot treat a very large drainage area. Large areas may be divided and treated using multiple swales. • A thick vegetative cover is needed for these practices to function properly. • They are impractical in areas with steep topography. • They are not effective and may even erode when flow velocities are high, if the grass cover is not properly maintained. • In some places, their use is restricted by law: many local municipalities require curb and gutter systems in residential areas. • Swales are mores susceptible to failure if not properly maintained than other treatment BMPs. -Design and Sizing Guidelines ... - - .. - ------ • Flow rate based design determined by local requirements or sized so that 85% of the annual runoff volume is discharged at less than the design rainfall intensity. • Swale should be designed so that the water level does not exceed 2/ 3rds the height of the grass or 4 inches, which ever is less, at the design treatment rate. • Longitudinal slopes should not exceed 2.5% • Trapezoidal channels are normally recommended but other configurations, such as parabolic, can also provide substantial water quality improvement and may be easier to mow than designs with sharp breaks in slope. • Swales constructed in cut are preferred, or in fill areas that are far enough from an adjacent slope to minimize the potential for gopher damage. Do not use side slopes constructed of fill, which are prone to structural damage by gophers and other burrowing animals. • A diverse selection of low growing, plants that thrive under the specific site, climatic, and watering conditions should be specified. Vegetation whose growing season co1Tesponds to the wet season are preferred. Drought tolerant vegetation should be considered especially for swales that are not part of a regularly irrigated landscaped area. • The width of the swale should be determined using Manning's Equation using a value of 0.25 for Manning's n. 2 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 - ----.. ----- - --- - -------- Vegetated Swale TC-30 Construction/Inspection Considerations • Include directions in the specifications for use of appropriate fertilizer and soil amendments based on soil properties determined through testing and compared to the needs of the vegetation requirements. • Install swales at the time of the year when there is a reasonable chance of suc.cessful establishment without irrigation; however, it is recognized that rainfall in a given year may not be sufficient and temporary irrigation may be used. • If sod tiles must be used, they should be placed so that there are no gaps between the tiles; stagger the ends of the tiles to prevent the formation of channels along the swale or strip. • Use a roller on the sod to ensure that no air pockets form between the sod and the soil. • Where seeds are used, erosion controls will be necessary to protect seeds for at least 75 days after the first rainfall of the season. Performance The literature suggests that vegetated swales represent a practical and potentially effective technique for controlling urban runoff quality. While limited quantitative performance data exists for vegetated swales, it is known that check dams, slight slopes, permeable soils, dense grass cover, increased contact time, and small storm events all contribute to successful pollutant removal by the swale system. Factors decreasing the effectiveness of swales include compacted soils, short runoff contact time, large storm events, frozen ground, short grass heights, steep slopes, and high runoff velocities and discharge rates. Conventional vegetated swale designs have achieved mixed results in removing particulate pollutants. A study performed by the Nationwide Urban Runoff Program (NURP) monitored three grass swales in the Washington, D.C., area and found no significant improvement in urban runoff quality for the pollutants analyzed. However, the weak performance of these swales was attributed to the high flow velocities in the swales, soil compaction, steep slopes, and short grass height. Another project in Durham, NC, monitored the performance of a carefully designed artificial swale that received runoff from a commercial parking lot. The project tracked 11 storms and concluded that particulate concentrations of heavy metals (Cu, Pb, Zn, and Cd) were reduced by approximately 50 percent. However, the swale proved largely ineffective for removing soluble nutrients. The effectiveness of vegetated swales can be enhanced by adding check dams at approximately 17 meter (50 foot) increments along their length (See Figure 1). These dams maximize the retention time within the swale, decrease flow velocities, and promote particulate settling. Finally, the incorporation of vegetated filter strips parallel to the top of the channel banks can help to treat sheet flows entering the swale. Only 9 studies have been conducted on all grassed channels designed for water quality (Table 1). The data suggest relatively high removal rates for some pollutants, but negative removals for some bacteria, and fair performance for phosphorus. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 3 of 13 - ------------- ---.. -.. ---- ----------- TC-30 Vegetated Swale Table 1 Grassed swale pollutant removal efficiency data Removal Efficiencies(% Removal) Study TSS TP TN N03 Metals Bacteria Type Caltrans 2002 77 8 67 66 83-90 -33 dry swales Goldberg 1993 67.8 4-5 -31.4 42-62 -100 grassed channel Seattle Metro and Washington 60 45 --25 2-16 -25 grassed channel Department of Ecology 1992 Seattle Metro and Washington 83 29 --25 46-73 -25 grassed channel Department of Ecology, 1992 Wang et al., 1981 So - - -70-80 -dry swale Dorman et al., 1989 98 18 -45 37-81 -dryswale Harper, 1988 87 83 84 80 88-90 -dryswale Kercher et al., 1983 99 99 99 99 99 -dryswale Harper, 1988. 81 17 40 52 37-69 -wetswale Koon, 1995 67 39 -9 -35 to 6 -wetswale While it is difficult to distinguish between different designs based on the small amount of available data, grassed channels generally have poorer removal rates than wet and dry swales, although some swales appear to export soluble phosphorus (Harper, 19 88; Koon, 1995). It is not clear why swales export bacteria. One explanation is that bacteria thrive in the warm swale soils . Siting Criteria The suitability of a swale at a site will depend on land use, size of the area serviced, soil type, slope, imperviousness of the contributing watershed, and dimensions and slope of the swale system (Schueler et al., 1992). In general, swales can be used to serve areas of less than 10 acres, with slopes no greater than 5 %. Use of natural topographic lows is encouraged and natural drainage courses should be regarded as significant local resources to be kept in use (Young et al., 1996). Selection Criteria (NCTCOG, 1993) • Comparable performance to wet basins • Limited to treating a few acres • Availability of water during dry periods to maintain vegetation • Sufficient available land area Research in the Austin area indicates that vegetated controls are effective at removing pollutants even when dormant. Therefore, irrigation is not required to maintain growth during dry periods, but may be necessary only to prevent the vegetation from dying. 4 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 -- --------------------- - ----------- Vegetated Swale TC-30 The topography of the site should permit the design of a channel with appropriate slope and cross-sectional area. Site topography may also dictate a need for additional structural controls. Recommendations for longitudinal slopes range between 2 and 6 percent. Flatter slopes can be used, if sufficient to provide adequate conveyance. Steep slopes increase flow velocity, decrease detention time, and may require energy dissipating and grade check. Steep slopes also can be managed using a series of check dams to terrace the swale and reduce the slope to within acceptable limits. The use of check dams with swales also promotes infiltration. Additional Design Guidelines Most of the design guidelines adopted for swale design specify a minimum hydraulic residence time of 9 minutes. This criterion is based on the results of a single study conducted in Seattle, Washington (Seattle Metro and Washington Department of Ecology, 1992), and is not well supported. Analysis of the data collected in that study indicates that pollutant removal at a residence time of 5 minutes was not significantly different, although there is more variability in that data. Therefore, additional research in the design criteria for swales is needed. Substantial pollutant removal has also been observed for vegetated controls designed solely for conveyance (Barrett et al, 1998); consequently, some flexibility in the design is warranted. Many design guidelines recommend that grass be frequently mowed to maintain dense coverage near the ground surface. Recent research (Colwell et al., 2000) has shown mowing frequency or grass height has little or no effect on pollutant removal. Summary of Design Recommendations 1) The swale should have a length that provides a minimum hydraulic residence time of at least 10 minutes. The maximum bottom width should not exceed 10 feet unless a dividing berm is provided. The depth of flow should not exceed 2/ 3rds the height of the grass at the peak of the water quality design storm intensity. The channel slope should not exceed 2.5%. 2) 3) 5) 6) 7) A design grass height of 6 inches is recommend~. Regardless of the recommended detention time, the swale should be not less than 100 feet in length. The width of the swale should be determined using Manning's Equation, at the peak of the design storm, using a Manning ·s n of o .25. The swale can be sized as both a treatment facility for the design storm and as a conveyance system to pass the peak hydraulic flows of the 100-year storm if it is located "on-line." The side slopes should be no steeper than 3:1 (H:V). Roadside ditches should be regarded as significant potential swale/buffer strip sites and should be utilized for this purpose whenever possible. If flow is to be introduced through curb cuts, place pavement slightly a hove the elevation of the vegetated areas. Curb cuts should be at least 12 inches wide to prevent clogging. Swales must be vegetated in order to provide adequate treatment ofrunoff. It is important to maximize water contact with vegetation and the soil surface. For general purposes, select fine, close-growing, water-resistant grasses. If possible, divert runoff (other than necessary irrigation) during the period of vegetation January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 5 of 13 -- -------• -----------------------• -- TC-30 Vegetated Swale establishment. Where runoff diversion is not possible, cover graded and seeded areas with suitable erosion control materials. Maintenance The useful life of a vegetated swale system is directly proportional to its maintenance frequency. If properly designed and regularly maintained, vegetated swales can last indefinitely. The maintenance objectives for vegetated swale systems include keeping up the hydraulic and removal efficiency of the channel and maintaining a dense, healthy grass cover. Maintenance activities should include periodic mowing (with grass never cut shorter than the design flow depth), weed control, watering during drought conditions, reseeding of bare areas, and clearing of debris and blockages. Cuttings should be removed from the channel and disposed in a local composting facility. Accumulated sediment should also be removed manually to avoid concentrated flows in the swale. The application of fertilizers and pesticides should be minimal. Another aspect of a good maintenance plan is repairing damaged areas within a channel. For example, if the channel develops ruts or holes, it should be repaired utilizing a suitable soil that is properly tamped and seeded. The grass cover should be thick; if it is not, reseed as necessary. Any standing water removed during the maintenance operation must be disposed to a sanitary sewer at an approved discharge location. Residuals (e.g., silt, grass cuttings) must be disposed in accordance with local or State requirements. Maintenance of grassed swales mostly involves maintenance of the grass or wetland plant cover. Typical maintenance activities are summarized below: • Inspect swales at least twice annually for erosion, damage to vegetation, and sediment and debris accumulation preferably at the end of the wet season to schedule summer maintenance and before major fall runoff to be sure the swale is ready for winter. However, additional inspection after periods of heavy runoff is desirable. The swale should be checked for debris and litter, and areas of sediment accumulation. • Grass height and mowing frequency may not have a large impact on pollutant removal. Consequently, mowing may only be necessary once or twice a year for safety or aesthetics or to suppress weeds and woody vegetation. • Trash tends to accumulate in swale areas, particularly along highways. The need for litter removal is determined through periodic inspection, but litter should always be removed prior to mowing. • Sediment accumulating near culverts and in channels should be removed when it builds up to 75 mm (3 in.) at any spot, or covers vegetation. • Regularly inspect swales for pools of standing water. Swales can become a nuisance due to mosquito breeding in standing water if obstructions develop (e.g. debris accumulation, invasive vegetation) and/or if proper drainage slopes are not implemented and maintained. 6 of 13 California Stormwater BMP Handbook New Development and Redevelopment www .cabmphandbooks.com January 2003 --------• ------- • -.. ---- - -- • • -.. -• -• Vegetated Swale Cost Construction Cost TC-30 Little data is available to estimate the difference in cost between various swale designs. One study (SWRPC, 1991) estimated the construction cost of grassed channels at approximately $0.25 per ft2. This price does not include design costs or contingencies. Brown and Schueler (1997) estimate these costs at approximately 32 percent of construction costs for most stormwater management practices. For swales, however, these costs would probably be significantly higher since the construction costs are so low compared with other practices. A more realistic estimate would be a total cost of approximately $0.50 per ft2, which compares favorably with other stormwater management practices. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www .cabmphandbooks.com 7 of 13 I I I I I I I I I I I I I I I I I I I I I I I I TC-30 Table 2 Swale Cost Estimate (SEWRPC, 1991) Unit Cost Component Unit Extent Low Moderate High Low Mobilization I Swale 1 $107 $274 $441 $107 Demobilization -Ug ht Sita Preparation Clearingb ................ Aae 0.5 $2,200 $3,800 $6,400 $1,100 Grubbing" .............. Aae 0.25 $3,800 $5,200 $8,600 $Q50 General ExcavatiorP ............ Yd3 372 $2.10 $3.70 $6.30 $7B1 Lave! and Till" ........ Yd2 1,210 ~.20 $0.35 ~.50 $242 Sitas Development Salvaged Topsoil Yd2 1,210 ~.40 $1.00 $1.60 $4B4 Seed, and Mulch' .. Sod! ...................... Yd2 1,210 $1.20 $2.40 $3.60 $1,452 subtotal --------$5,116 Contingencies Swale 1 25'1. 25% 25% $1,27Q Total --------$8395 Source: (SEWRPC, 1QQ1) Note: Mobilization/demobilization refers to the organization and planning involved in establishing a vage1ative swale. • Swale has a bottom width of 1.0 foot, a top width of 10 feet with 1 :3 side slopes, and a 1,000-foot length. b Area cleared = (top width + 1 O feet) x swale length. 0 Area grubbed = (top width x swale length). dVolume excavated = (0.67 x top width x swale depth) x swale length (parabolic cross-section) . .. Area tilled= (top width + 8(swale depth2) x swale length (parabolic cross-section). 3(top width) 'Area seeded= area cleared x 0.5. e Area sodded = area cleared x 0.5. a of 13 California storrnwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com I I I I l J ; .. Vegetated Swale Total Cost Moderate High $274 $441 $1,QOO $2,700 $1,300 $1,650 $1,376 $1,972 $424 $605 $1,210 $1,Q36 $2,Q04 $4,356 $Q,388 $13,680 $2,347 $3,415 $11 735 $17 075 January 2003 I I I I I I I I I I I I I I I I I I I I I I I I I Vegetated Swale Table 3 Estimated Maintenance Costs (SEWRPC. 1991) Component Unit Cost Lawn Mowing $0.8511,000 fl:21 mov.ing General Lawn Care $9.00 I 1,000 ft21 year Swale Debris and Utter $0.10 / linear foot I year Removal Grass Reseeding with $0.30/yd2 Mulch and Fertilizer Program Administration and $0.1 51 linaar feet I year, Swale Inspection plus $25 I inspecii on Total .. --~---... -. January 2003 Swale Size (Depth and Top WVldth) 1.5 Foot Depth, One-3-F oot Depth, 3-F oot Foot Bottom Width, Bottom WVldth, 21.foot 10-Foot Top Width Top Width $0.14 /linearfaot $0 .21 / Ii near faot $0.18 / linearfaot $0 .28 / Ii near foot $0.10 / linear foot $0.10 / linear foot $0.01 / linearfoot $0.01 / Ii near foot $0.15 llinearfoot $0.15 I linear foot $0.58 / llnear foot $ 0.75 / lin .. foot California stonnwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com I I I I I I I I I I I I TC-30 Comment Lawn maintenance araa=(top wid1h + 1 0 feet) x length. Mow eight times per year Lawn ma intenanc:a area = (top wid1h + 10feat) xleng1h - Area rawgetatad equals 1 % of lawn maintenance area per year Inspect four times par year - 9 of 13 - --- --- - -- ---.. ---.. TC-30 Vegetated Swale Maintenance Cost Caltrans (2002) estimated the expected annual maintenance cost for a swale with a tributary area of approximately 2 ha at approximately $2,700. Since almost all maintenance consists of mowing, the cost is fundamentally a function of the mowing frequency. Unit costs developed by SEWRPC are shown in Table 3. In many cases vegetated channels would be used to convey runoff and would require periodic mowing as well, so there may be little additional cost for the water quality component. Since essentially all the activities are related to vegetation management, no special training is required for maintenance personnel. References and Sources of Additional Information Barrett, Michael E., Walsh, Patrick M., Malina, Joseph F., Jr., Charbeneau, Randall J, 1998, "Performance of vegetative controls for treating highway runoff," ASCE Journal of Environmental Engineering, Vol. 124, No. 11, pp.1121-1128. Brown, W., and T. Schueler. 1997. The Economics of Storm water BMPs in the Mid-Atlantic Region. Prepared for the Chesapeake Research Consortium, Edgewater, MD, by the Center for Watershed Protection, Ellicott City, MD. Center for Watershed Protection (CWP). 1996. Design of Storm water Filtering Systems. Prepared for the Chesapeake Research Consortium, Solomons, MD, and US EPA Region V, Chicago, IL, by the Center for Watershed Protection, Ellicott City, MD. Colwell, Shanti R., Horner, Richard R., and Booth, Derek B., 2000. Characterization of Performance Predictors and Evaluation of Mowing Practices in Biofiltration Swales. Report to King County Land And Water Resources Division and others by Center for Urban Water Resources Management, Department of Civil and Environmental Engineering, University of Washington, Seattle, WA Dorman, M.E., J. Hartigan, R.F. Steg, and T. Quasebarth. 1989. Retention, Detention and Overland Flow for Pollutant Removal From Highway Stormwater Runoff Vol.1. FHWA/RD 89/202. Federal Highway Administration, Washington, DC. Goldberg. 1993. Dayton Avenue Swale Bio.filtration Study. Seattle Engineering Department, Seattle, WA. Harper, H. 1988. Effects ofStormwater Management Systems on Groundwater Quality. Prepared for Florida Department of Environmental Regulation, Tallahassee, FL, by Environmental Research and Design, Inc., Orlando, FL. Kercher, W.C., J.C. Landon, and R. Massarelli. 1983. Grassy swales prove cost-effective for water pollution control. Public Works, 16: 53-55. Koon, J. 1995. Evaluation of Water Quality Ponds and Swales in the Issaquah/East Lake Sammamish Basins. King County Surface Water Management, Seattle, WA, and Washington Department of Ecology, Olympia, WA. Metzger, M. E., D. F. Messer, C. L. Beitia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side Of Stormwater Runoff Management: Disease Vectors Associated With Structural BMPs . Stormwater 3(2): 24-39.0akland, P.H. 1983. An evaluation of stormwater pollutant removal 10 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 -- - ... - -.. ---- - - --.. -------- Vegetated Swale TC-30 through grassed swale treatment. In Proceedings of the International Symposium of Urban Hydrology, Hydraulics and Sediment Control, Lexington, KY. pp. 173-182. Occoquan Watershed Monitoring Laboratory. 1983. Final Report: Metropolitan Washington Urban Runoff Project. Prepared for the Metropolitan Washington Council of Governments, Washington, DC, by the Occoquan Watershed Monitoring Laboratory, Manassas, VA. Pitt, R., and J. McLean. 1986. Toronto Area Watershed Management Strategy Study: Humber River Pilot Watershed Project. Ontario Ministry of Environment, Toronto, ON. Schueler, T. 1997. Comparative Pollutant Removal Capability of Urban BMPs: A reanalysis. Watershed Protection Techniques 2(2):379-383. Seattle Metro and Washington Department of Ecology. 1992. Bio.filtration Swale Performance: Recommendations and Design Considerations. Publication No. 657. Water Pollution Control Department, Seattle, WA. 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. U.S. EPA, 1999, Stormwater Fact Sheet: Vegetated Swales, Report# 832-F-99-006 htt,p://www.epa.gov/owm/mtb/vegswale.pdf, Office of Water, Washington DC. Wang, T., D. Spyridakis, B. Mar, and R. Horner.1981. Transport, Deposition and Control of Heavy Metals in Highway Runoff. FHWA-WA-RD-39-10. University of Washington, Department of Civil Engineering, Seattle, WA. Washington State Department of Transportation, 1995, Highway Runoff.Manual, Washington State Department of Transportation, Olympia, Washington. Welborn, C., and J. Veenhuis. 1987. Effects of Runoff Controls on the Quantity and Quality of Urban Runoff in Two Locations in Austin, TX. USGS Water Resources Investigations Report No. 87-4004. U.S. Geological Survey, Reston, VA. Yousef, Y., M. Wanielista, H. Harper, D. Pearce, and R. Tolbert. 1985. Best 1\1[anagement Practices: Removal of Highway Contaminants By Roadside Swales. University of Central Florida and Florida Department of Transportation, Orlando, FL. Yu, S., S. Barnes, and V. Gerde. 1993. Testing of Best Management Practices for Controlling Highway Runoff FHWA/VA-93-R16. Virginia Transportation Research Council, Charlottesville, VA. Information Resources Maryland Department of the Environment (MDE). 2000. lvfaryland Stormwater Design !vlanual. www.mde.state.md.us/environment/wma/stormwatermanual. Accessed May 22, 2001. Reeves, E. 1994. Performance and Condition of Biofilters in the Pacific Northwest. Watershed Protection Techniques 1(3):117-119. January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com 11 of 13 -- - ------------- --.. -- - ----------• TC-30 Vegetated Swale Seattle Metro and Washington Department of Ecology. 1992. Biofiltration Swale Performance. Recommendations and Design Considerations. Publication No. 657. Seattle Metro and Washington Department of Ecology, Olympia, WA. USEPA 1993. Guidance Specifying Management Measures for Sources ofNonpoint Pollution in Coastal Waters. EPA-840-B-92-002. U.S. Environmental Protection Agency, Office of Water. Washington, DC. Watershed Management Institute (WMI). 1997. Operation, Maintenance, and Management of Stormwater Management Systems. Prepared for U.S. Environmental Protection Agency, Office of Water. Washington, DC, by the Watershed Management Institute, Ingleside, MD. 12 of 13 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com January 2003 -- - - --------------- ------• -• -• -• -• Vegetated Swale Notation: Pro,ide for scour prOlection. (a) Cross section or swale with dl«k dam. L = Lonott, of swale impoundmont area per chock darn (It) (bl Dimen,loul ,.le,. or swale lmpoHdmHI area. Ds = Deptil of check dam (II) Ss = Bottom slpe of swale (ft/ft) W = Top widlh of check dam(II) W8 : Bollom widlh of chock dam (ft) Z141 = Ratio of horizont&l lo wnical chaflllO in swale sldo sl~ (It/ft) January 2003 California Stormwater BMP Handbook New Development and Redevelopment www.cabmphandbooks.com TC-30 13 of 13 Bioretention General Description The bioretention best management practice (BMP) functions as a soil and plant-based filtration device that removes pollutants through a vadety of physical, biological, and chemical treatment processes. These facilities normally consist of a grass buffer strip, sand bed, ponding area, organic layer or mulch layer, planting soil, and plants. The runoffs velocity is reduced by passing over or through a sand bed and is subsequently distributed evenly along a ponding area. Exfiltration of the stored water in the bioretention area planting soil into the underlying soils occurs over a period of days. Inspection I Maintenance Considerations Bioretention requires frequent landscaping maintenance, including measures to ensure that the area is functioning properly, as well as maintenance of the landscaping on the practice. In many cases, bioretention areas initially require intense maintenance, but less maintenance is needed over time. In many cases, maintenance tasks can be completed by a landscaping contractor, who may already be hired at the site. In cold climates the soil may freeze, preventing runoff from infiltrating into the planting soil. January 2003 California Stormwater BMP Handbook Industrial and Commercial www .cabmphandbooks.com TC-32 Maintenance Concerns, Objectives, and Goals • Oogged Soil or Outlet Structures • Invasive Species • Vegetation/Landscape Maintenance • Erosion • Channelization of Flow • Aesthetics Targeted Constituents ./ Sediment ./ Nutrients ./ Trash ./ Metals ./ Bacteria ./ Oil and Grease ./ Organics Legend (Removal Effectiveness) • .. Low • High Medium ~--SQA U Cllllfornla Stormwater O&Nlllly Association • .. • • • • • 1 of 3 I I I I I I I I TC-32 Bioretention • Inspect soil and repair eroded areas. • Inspect for erosion or damage to vegetation, preferably at the end of the wet season to schedule summer maintenance and before major fall runoff to be sure the strips are ready for winter. However, additional inspection after periods of heavy runoff is desirable. • Inspect to ensure grass is well established. If not, either prepare soil and reseed or replace with alternative species. Install erosion control blanket. • Check for debris and litter, and areas of sediment accumulation. • Inspect health of trees and shrubs. • Water plants daily for 2 weeks. • Remove litter and debris. • Remove sediment. • Remulch void areas. • Treat diseased trees and shrubs. • Mow turf areas. • Repair erosion at inflow points. • Repair outflow structures. • Unclog underdrain. • Regulate soil pH regulation. • Remove and replace dead and diseased vegetation • Add mulch. • Replace tree stakes and wires. Monthly Semi-annual inspection At project completion Monthly As needed Semi-annual Annual • Mulch should be replaced every 2 to 3 years or when bare spots appear. Remulch prior to Every 2-3 years, or the wet season. as needed Additional Information Landscaping is critical to the function and aesthetic value of bioretention areas. It is preferable to plant th e area with native vegetation, or plants that provide habitat value, where possible. Another important design feature is to select species that can withstand the hydrnlogic regime they will experience. At the bottom of the bioretention facility, plants that tolerate both wet and dry conditions are preferable. At the edges, which will remain primarily dry, upland species will be the most resilient. It is best to select a combination of trees, shrubs, and herbaceous mate1ials. References Metropolitan Council, Urban Small Sites Best Management Practices Manual. Available at: http://www.metrocouncil.org/environment/W atershed/BMP /manual.htm 2 of 3 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com January 2003 -• -------------------• -• -• -• • 1111 • -• -• Bioretention TC-32 Model Urban Runoff Program: A How-To Guide for Developing Urban Runoff Programs for Small Municipalities. Prepared by City of Monterey, City of Santa Cruz, California Coastal Commission, Monterey Bay National Marine Sanctuary, Association of Monterey Bay Area Governments, Woodward-Clyde, Central Coast Regional Water Quality Control Board. July, 1998, revised February, 2002. U.S. Environmental Protection Agency, Post-Construction Stormwater Management in New Development & Redevelopment BMP Factsheets. Available at: cf:pub.epa.gov/npdes/stormwater/menuofbmps/bmp files.cfm Ventura Countywide Stormwater Quality Management Program, Technical Guidance Manual for Stormwater Quality Control Measures. July, 2002. January 2003 California Stormwater BMP Handbook Industrial and Commercial www.cabmphandbooks.com 3 of 3 X ( 2sa s X ASPH 240.5 X 06 , ' 0 ~ ( I I 2~.7 ,< (---- ,I .----- _I I I I By: ~le: i2·Q;;201( Name: Richard C. Brasher R.C.E.: 43819 exp: 6-30-2013 9 PANGAEA LAND CONSULTANTS. INC. ')IRT '-""- r•......... L........__J l ~" ", '\ 1 \ ( ~ "-_,,,,~ \ 1 ~ ' ( ~ \ i? -/ "'"' ,s i L \ '\ \ \ I '- I "'>o, "'"' "' \ ~~ I \ \ \ l : \ \ I L, I I \ \ \ I / r \ \ ~ I < BMP ID# BMPTYPE SYMBOL CASQA NO. I I TREATM ENT CONTROL CD BIO-RETENTION I I TC-32 BASIN 0-® PERVIOUS Imm I PAVERS SD-20 I ' I I I I I I I I I LOW IMPAC T D ESIG N (LJD.) CD BIO-RETENTION I I TC-32 BASIN 0-® PERVIOUS SD-20 PAVERS S OURCE CONTR O L ®-®I -INLET I • I STENCIUNG SD-13 LANDSCAPING/ IALL GRADED PESTICIDE AREAS SD-10 LEGEND: PROPOSED DRAINAGE F ACUITIES \ W / _J I (.) a: I BMP TABLE QUANTITY DRAWIN G NO. SHEET NO.(S) INSPECTION MAINTENANCE FREQUENCY FREQUENCY 1 469-5A 3, 7 BEGINNING OF BEGINNING OF RAINY SEASON RAINY SEASON 8 469-5C 3 • 10 ANNUALLY EVERY 3 MONTHS 1 469-5A 3, 7 BEGINNING OF BEG INNIN G OF RAINY SEASON RAINY SEASON 8 469-5C 3 · 10 ANNUALLY EVERY 3 MONTHS 13 469-5A I 469-58 8/4 ANNUALLY AS-NEEDED 1 469-58 I 469-5L 7-1711 -25 WEEKLY WEEKLY \ "" ~- "· \ \ \ CONSTRUCTION SIGN OFF \ \ X 275.3 X 277.3 X i ' ,--~ ---/ I SWMP NO. -~1_0-_14~_ MAINTENANCE AGREEMENT DOCUMENT: YES _x_ NO RECORDATION NO. TO BE DETERMINED PARTY RESPONSIBLE FOR MA INTENANCE: NAME: SHEA HOMES ADDRESS 9990 MESA RIM ROAD SAN DIEGO CA 92121 PHONE NO. (8 58) 526-6554 PLAN PREPARED BY: NAME RICH BRASHER CONTACT SARAH BECKMAN COMPANY PANGAEA LAND CONSULTANTS. INC. ADDR ESS 2834 LA MIRADA DRIVE, SUITE H VISTA CA 92081 PHONE NO. (760) 726-4232 CERTIFICATION PE 43819 BMP NOTES: / I ) 1. THESE BMPS ARE MANDATORY TO BE INSTALLED PER MANUFACTURER'S RECOMMENDATIONS OR THESE PLANS. 2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 3. NO SUBSTITUTIONS TO THE MATERIAL OR TYPES OR PLANTING TYPES WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 4. NO OCCUPANCY WILL BE GRANTED UNTIL THE CITY INSPECTION STAFF HAS INSPECTED THIS PROJECT FOR APPROPRIATE BMP CONSTRUCTION AND INSTALLATION. VERIFIED BY: IN SPECTOR DATE I SHE1ET I CITY OF CARLSBAD ~~ 1-----+--+---------------+----+---t----r---i ENGINEERING DEPARTMENT ~ l----+--+---------------+---+--+---i-----1~B~M~P=S~IT~E;;::;P~LAN:::;;::====================-'====--, CT 04-10 (A) POIN SETTIA PLACE (SWMP 10-14) I -l----+--+---------------+---+--+---i-----1 I APPROVED: GLEN K. VAN PESKI l----+--+---------------+---i---+--~----1 ,ENGINEERING MANAGER PE 41 204 EXPIRES 3/31/13 DATE j DWN BY: PROJECT NO. I DRAWING NO. CHKD BY: 469-SSW RVWD BY: DATE INl11AL ENGINEER OF WORK DA TE INITIAL DA TE INITIAL R EVI SION DESCRIPTION OTHER APPROVAL CITY APPROVAL I i ' / ~ v/" BASIN F, REBA Y AREA ) SEE BIO RETEN ,/ON BASIN CROSS SECTION A-A AND 8-8 ETA/LS ON SHEET 3 I'J PLAN VIEW: BIO-RETENTION BASIN SCALE: 1 "=20' SECTION A-A: BIO-RETENTION BASIN NOT TO SCALE ~-BASIN OUTLET -'U' SHAPED HEADWALL WITH SLOPING BOTTOM PER D-34 TOP OF HEADWALL 230.50 ~--CABLE RAIL FENCE ON TOP OF HEADWALL PER CALTRANS STD B11-47 u·, I /' '\);,, /l, 18" PLANTING MIX PER '\>'f;/> :J 'tANDSCAPE ARCHITECT //, ~ ,i ~ SPECIFICATION BOTTOM OF BASIN FOREBAY/ '\>;{o"' (:J J , ELEVATION 230.00 \CLEANOUT ~~~t/: ~ -:~ f: :: : it:: ::: ::~t:: ::: :: f::::: -.:·:f :~ ~;_0 t,i?\_s \_ §!~1:S~LET PIPE /;,(· .. · ,,,. ,,,,,,,.,,,,,, .• , .• , .• , •. , .. ,.,.-,,: • ,, ,;,,,, •• ' ,.-,,., ',,.,,,, •• • / HEADWALL BASIN OUT~Jf ~~t "-7" . . . . ·· · .. · ' ··. . . · . . .· · . '/,v"-RIP RAP ' \ ''" '-.7)._ "->'>--"->" :,:" ~"" 'f,"" '{,"' '{,"-. V.:,"-. v;,"-~" "-'"' ~,;' 'j,./ 6',\j ;(24" MIN. THICKNESS -AGGREGATE -0 ·o, 6" PVC PERFORATED PIPE PERMEABLE MATERIAL PER SOILS 'f, 0,, SLOPING AT 0.5% MIN. ENGINEER SPECIFICATION < TOWARD OUTLET STRUCTURE END CAP 226_5 FL SECTION B-B: BIO-RETENTION BASIN NOT TO SCALE ~ I NOTE: SEE SITE MAP FOR BIO-RETENTION (CASQA NO. TC~32) AND PERVIOUS PAVER (CASQA NO. SD-20) LOCATIONS. GRAPHIC SCALE 20 0 10 20 40 11111 -l~M .. J I I 1 INCH = ·20 FEET I P4 - - . ' . - STREET GRADE _/ ..._ 1"'-1D'-4" PERFORATE~~ (PER PLAN) 4" PVC (SOLID) A PIPE WITH END CAP CONCRETE CURB ----===--· -·. --.. -____ 11 ___ ~---· ________ ~ ···-__ AN_D GUTIER FLOW .. D= AC STREET ___ _ STORM o RAI N7 it========="~==c=::o=N=NE::::C;T:::::::::TO::=S::::T::::O::::R M==D:;;R==A==I N ----- GUTTER FLOWLINE AC DRIVEWAY LENGTH PER PLAN AC STREET SLOPE PER PLAN PERVIOUS PAVERS :,;;;;:,::,,:,::,;:-;:,:,-,:: SLOPE PER PlA 7.% •• ,;,,:::::'.: lj_lT ~rlill~~illffl ~ N . ~;::~;,·t~~II~~ =JC -I , : , •:: •c;, I '"";;a 11,,. -;c- ,,,. ,TT 2' ='ffi ~~ill" '--, . MATCH DRIVEWAY SL 2' jlf~ll;c;;;'lc;. CONCRETE CURB/ GUTTER 11-111-1~111~11,-. :---..::. OP[ ell. I u,, ,ill "111 -11i1 I IIIEI 11lli11~1T""Tn'= = -F1 I ' -w ··1=111=1 11111111'"11E 11 ·~ -'-Ill-=:::=! II-' 1~11 PERMEABLE/ STRUCTURAL BASE PER SOILS ENGINEER 1 O' -4" PERFORATED PIPE SPECIFICATIONS SECTION A-A: DRIVEWAY PERVIOUS PAVER NOT TO SCALE LENGTH PER PLAN 90% ELBOW _'ij 4" PVC (SOLID) DRAIN ~,,rn;;mf' TO STORM DRAIN IN STREET END CAP PERMEABLE/ STRUCTURAL BASE PER SOILS ENGINEER SPECIFICATIONS 1 O' -4" PERFORATED PIPE SECTION B-B: DRIVEWAY PERVIOUS PAVER NOT TO SCALE =r -[ _WITH LULr;tNECTIDl'f="I -- PLAN VIEW: DRIVEWAY PERVIOUS PAVER SCALE: 1 "=20' SWMP NO. 10-14 MAINTENANCE AGREEMENT DOCUMENT: YES NO __ RECORD A TION NO. PARTY RESPONSIBLE FOR MAINTENANCE: NAME CONTACT-----~ ADDRESS PHONE NO. PLAN PREPARED BY: BMP NOTES: CHANG CONSULTANTS P.O. BOX 9496 RANCHO SANTA FE, CA 92067 (858) 692-0760 CERTIFICATION: PE 46548, EXP. 6/30/11 1. THESE BMPS ARE MANDA TORY TO BE INSTALLED PER MANUFACTURER'S RECOMMENDATIONS OR THESE PLANS. 2. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 3. NO SUBSTITUTIONS TO THE MATERIAL OR TYPES OR PLANTING TYPES WITHOUT PRIOR APPROVAL FROM THE CITY ENGINEER. 4. NO OCCUPANCY WILL BE GRANTED UNTIL THE CITY INSPECTION STAFF HAS INSPECTED THIS PROJECT FOR APPROPRIATE BMP CONSTRUCTION AND INSTALLATION. VERIFIED BY: INSPECTOR DA TE I SHE1ET I CITY OF CARLSBAD I SHE1ETS I f-----+--+----------------1---+----t---+----l ENGINEERING DEPARTMENT 1----+--+-----------------,---+----t---+----i 1----+--+-----------------,---+----t---+----i BMP SITE PLAN POINSETTIA PLACE (SWMP 10-14) APPROVED: GLEN K. VAN PESKI SENIOR CIVIL ENGINEER PE 41204 EXPIRES 3 31 13 DATE ~=====:::::::::::::::::=::;'-;::::======:::::::::==-::::::::==-:======~, 1--~--+~~----------------t---+----+--+----l DWN BY: ---PROJECT NO. I DRAWING NO. DATE INITIAL DATE INITIAL DATE INITIAL CHKD BY: __ ENGINEER OF WORK REVISION DESCRIPTION OTHER APPROVAL CITY APPROVAL RVWD BY: ( \ r~ I <! ., ' 'I I _,,J ~ 'v\._, . 245.4 X D 240.6 X LEGEND: I I I • " ' I /I f I 243.5 ' \ ___ X \ I I ' X --DRAINAGE FACLIITIES -BIO-RETENTION AREA I PERVIOUS PAVERS I STREET, CURB, GUTTER, AND SIDEWALK ~- I INTERIOR WALKWAYS -- I ROOFS (TRIBUTARY TO BIO-RETENTION AREA) ~- --ROOFS AND DRIVEWAYS (TRIBUTARY TO PERVIOUS PAVERS) -• I 2635 I "'0 ~ '---aro., L _J ] J -'y::(~ / w ~/ \ ~~ \ ,J '=====26 "~~ ~ E' 1 X L __ I uic -~_J?-,~, -~ -+ X 211.9 u:c 271 ~~ -. _J;5i; '-~. ,-.,~ I \ --\ ~ ----27 --> ----,~ -===========~ : -__J ~ = '-...) I . ~ X 275.3 -. X 265.2 270 '--I"',,/ X ....____ " ~ ~ '"' 'l". -" _....f"" ~ L...l..... "" ._ 275 ----=-----2ZB...6_ _.----~' ==,......_ ~ --~-· 6 ~ ,,-.,~ ---------~260 • o ~ -~, 25&.= _, , ./ _J ,_ 1 ~ L "-... ~ ~-= :::-"-- 0 u, N en N -- II 0 "" Q • • J • DIRT & DE3RJS PILES POINSETT A PLACE SITE MAP AND LID DESIGN NOTE: THE LANDSCAPE AREAS AND UNDISTURBED NATURAL TERRAIN ARE NOT SHADED. GRAPHIC SCALE ~ 0 W ~ ~ ~I ----~-"il_M".-..21 ~1--1 ( IN FEET ) 1 inch = 40 ft. SWMP