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Home My WebLink AboutSDP 14-01; RACEWAY BUSINESS PARK LOT 18; STORM WATER MANAGEMENT PLAN SWMP 14-05; 2014-06-30I Z-7 STORM WATER MANAGEMENT PLAN SWMP 14-05 FOR LOT 17 CARLSBAD RACEWAY BUSINESS PARK PLANNED INDUSTRIAL PERMIT SDP 14-01 DWG 482-5A GR 14-18 September 4, 2013 Revised June 30, 2014 Prepared For: Burke Real Estate Group 260 E. Baker Street, Suite 100 Costa Mesa, CA 92626 Prepared By: O'DAY CONSULTANTS, INC. 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010 J.N. 13-1020-03 .SR~011CINA- , Lot 17 - Carlsbad Raceway Business Park SWMP TABLE OF CONTENTS TABLEOF CONTENTS........................................................................................................................ ATTACHMENTS:............................................................................................................................... ii 1. PROJECT SETTING ....................................................... . ......................................................... 1 2. APPLICABLE STORM WATER STANDARDS ............................................................................3 Storm Water Standards Questionnaire.........................................................................3 HMP Applicability Determination..................................................................................3 3. IDENTIFY POLLUTANTS OF CONCERN..................................................................................4 Identify pollutants associated with type of project/use ...............................................4 Identify watershed, hydrologic unit basin and receiving waters ..................................4 List impaired water bodies ............................................................................................5 Beneficial uses of receiving water .................................................................................5 Summarize primary pollutants of concern ....................................................................6 4. SOURCE CONTROL MEASURES .............................................................................................. 8 Description of site activities and potential sources of pollutants.................................8 Stormwater Pollutant Sources and Source Controls ............... ......................................8 5. LOW IMPACT DEVELOPMENT (LID) DESIGN STRATEGIES..................................................11 6. INTEGRATED MANAGEMENT PRACTICES (IMP's)..............................................................12 Selection process for IMP's..........................................................................................12 Sizing factors for IMP's.................................................................................................12 Geotechnical recommendation on soil infiltration rates ............................................12 Infiltration calculations................................................................................................12 7. TREATMENT CONTROL BMP's ...........................................................................................13 8. HYDROMODIFICATION.......................................................................................................14 Lower Flow Threshold Determination..........................................................................14 Continuous Simulation Model .....................................................................................15 Tabulation of Flow-control Facility Sizes and Design Criteria......................................15 9. DOCUMENTATION OF STORM WATER DESIGN..................................................................16 Hydrology maps ........................................................................................................... 16 BMP Sizing Calculator ..................................................................................................16 10. BMP FACILITY MAINTENANCE REQUIREMENTS................................................................17 10a. Ownership and responsibility of maintenance of BMP's ............................................17 lOb. Summary of maintenance requirements.....................................................................17 11. SWMP CERTIFICATION STATEMENTS ................................................................................18 1 Lot 17 - Carlsbad Raceway Business Park ATTACHMENTS: Storm Water Standards Questionnaire BMP and DMA Plan Exhibit SWMM Program Results Urban Green®Biofiltration Specifications and Details Bioretention Basin Specifications and Details Bio Clean Trench Drain Insert I:\131020\Stormwater_SiteSWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 1. PROJECT SETTING Lot 17 of Carlsbad Raceway Business Park project is located north of Lionshead Avenue and east of Melrose Drive in the City of Carlsbad, California (see Vicinity Map below). The entire site is approximately 4.8 acres. Lot 17 is an existing mass graded lot per approved grading plan Drawing 409- 1A. The purpose of this preliminary SWMP is to support a Planned Industrial Permit "PIP" which proposes the development of the site for industrial use. The site will include approximately 76,326 S.F. of building permit area (includes truck docks and trash enclosures) and approximately 177 parking spaces. The remainder of the site will be landscaping. CITY OF OCEANSIDE SITE BUSINESS PARK DR. CITY OF SAN MARCOS CITY OF ENCII.JITAS V/C/N/TV IWI4P NO SCALE 1 I:U31020\Stormwater_Sitc\SWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park The existing site drains towards the northeasterly corner into a desilting basin that drains to an existing 54-inch storm drain that traverses the project in a south to northerly direction. The County of San Diego Hydrology Manual Soil Hydrologic Group identifies Soil Group D as the predominant soil type Hydrologic Soils Group D soils have a very slow infiltration rate (high runoff potential) when thoroughly wet. These soils have a very slow rate of water transmission. The proposed land use is Commercial use. Typical activities that could affect storm water include: Loading docks; landscape maintenance; pest control; hazardous material use; refuse services; storage; fire sprinkler testing; and miscellaneous wash water. Stormwater control and treatment constraints include: poor soil type and permeability (soil type D); high intensity land use; steep terrain; heavy pedestrian or vehicular traffic; restricted right-of-way; and safety concerns. Opportunities include landscape buffer areas and elevation differences. Under existing conditions, there is a single location where runoff from the lot discharges to, as indicated on City of Carlsbad Grading Plans Drawing No. 409-1A, sheet 14 and Drawing No. 409-1, sheet 23. Runoff from the site drains to an existing desilting basin that is connected to a 54-inch-storm drain that traverses the site and then discharges into an existing downstream detention basin west of Lot 17. The 54-inch storm drain is part of the existing drainage infrastructure serving the surrounding Carlsbad Raceway Business Park. The controlled discharge from the downstream detention basin eventually discharges to Agua Hedionda Creek, which ultimately flows into Agua Hedionda Lagoon and finally the Pacific Ocean. Under proposed conditions, the majority of the site drains toward the northeasterly corner of the site (Point of Compliance No. 1) . The remaining portion of the site will drain towards the south, near Lionshead Avenue (Point of Compliance No. 2). Treatment and flow controls will be done on all site drainage prior to entering the City's storm drain system. Discharge points to the City's MS4 remain unchanged. I:\13 IO2O\StormwaterSite\SWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 3. IDENTIFY POLLUTANTS OF CONCERN 3a. Identify pollutants associated with type of project/use Table 2-1 of the SUSMP (see below) identifies the pollutants anticipated from the Lot 17 commercial development and associated improvements as indicated by the shaded categories. TABLE 2-1. ANTICIPATED AND POTENTIAL Pollutants Generated by Land Use TvDe. General Pollutant Categories Trash Oxygen Bacteria Prioriy Project Ficavy Organic & Demanding Oil & & Categories Sediment Nutrients Metals Compounds Debris Substances Grease Viruses Pesticides Detached Residential X X X X X X X Development Attached Roidential X X X P(1) P(2) P X Development Co,,,menial Development . P(I) P(1) X 1)(2) X 11(5) X 1)(3) 11(5) >011e acre - - Heavy I,,d,istty X X X X X X Automotive X(4)(5) X X Repair Shops Restaurants X X X X P(l) Hillside Development X X X X X X >5,000 ft2 Parking Lots P(1) P(I) X X P(1) X P(1) Retail Gasoline x X X x Outlets Streets, Highways & X P(1) X X(4) X P(5) X X P(l) Freeways X = anticipated P = potential A potential pollutant if landscaping exists on-site. A potential pollutant if the project includes uncovered parking areas. A potential pollutant if land use involves food or animal waste products. Including petroleum hydrocarbons. Including solvents. 3b. Identify watershed, hydrologic unit basin and receiving waters The project is located in the Agua Hedionda Hydrologic Subarea (904.31) of the Carlsbad Hydrologic Unit in the San Diego Region All site drainage from Lot 17 enters the City of Carlsbad's MS4 at two separate locations along storm drain traversing the site. Flows from the site confluences with flows from surrounding developments before being conveyed northwesterly to an existing downstream detention basin located west of Melrose Drive. It then enters Agua Hedionda Creek approximately 1.5 miles downstream, and Agua Hedionda Lagoon about 3.0 miles further downstream. 4 !:\13 I020\Stormwater_Site\SWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park List impaired water bodies According to the California 2006 303(d) list of Water Quality limited Segments published by the RWQCB, there are currently no TMDL5 established for Agua Hedionda Lagoon or Agua Hedionda Creek. Agua Hedionda Lagoon is impaired by indicator bacteria and sedimentation/siltation. Agua Hedionda Creek is listed as Impaired with Manganese, selenium, sulfates and total dissolved solids. Beneficial uses of receiving water The beneficial uses for the hydrologic unit are indicated in Table 2-2 and 2-3 and described in detail below. This information comes from the Water Quality Control Plan for the San Diego Basin. Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS BENEFICIAL USE Hydrologic F p R R B W C W R 5 In land Surface Waters 1,2 Unit Basin M A I G R E E I A 0 I A P Number G NLR C CO R L L R W N R DR H12 I MD DEN Agua Hedionda Watershed _________ Agua Hedionda Lagoon 4.31 See Coast Water—Table 2-3 Agua Hedionda Creek 4.31 I I I I I I I I I I I + Excepted from MUN 'Waterbodies are listed multiple times if they cross hydrologic area or sub area boundaries. o Existing Beneficial use 2 Beneficial use designations apply to all tributaries to the indicated waterbody, if not listed separately. Table 2-3. BENEFICIAL USES OF COASTAL WATERS BENEFICIAL USE - - - - Hydrologic I N R R C B E W R A M S W Coastal Waters Unit Basin N A E E 0 I I A Q I P A Number Dy12 CC MO T I R U G W R ML D ERA R N M Agua Hedionda Lagoon i . - . . . . . . . . .. . Beneficial Uses of Inland Surface Waters 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 - Aquaculture: Includes the uses of water for aquaculture or mariculture operations including, but not limited to, propagation, cultivation, maintenance, or harvesting of aquatic plants and animals for human consumption or bait purposes. REC 1 —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. REC 2 —Non-Contact Recreation: Includes the uses of water for recreational activities involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, picnicking, sunbathing, hiking, beachcombing, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities. 5 I:\131020\Stormwater_Site\SWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park 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 food and sources. Beneficial Uses of Coastal Waters REC 1—See Beneficial Uses of Inland Surface Waters above REC 2 - See Beneficial Uses of Inland Surface Waters above BIOL - Preservation of Biological Habitats of Special Significance: Includes uses of water that support designated areas or habitats, such as established refuges, parks, sanctuaries, ecological reserves, or Areas of Special Biological Significance (ASBS), where the preservation or enhancement of natural resources requires special protection. EST— Estuarine Habitat: Includes the uses of water that support estuarine ecosystems including, but not limited to, preservation or enhancement of estuarine habitats, vegetation, fish, or wildlife (e.g., estuarine mammals, waterfowl, shorebirds). WILD - See Beneficial Uses of Inland Surface Waters above RARE - Rare, Threatened, or Endangered Species: Includes uses of water that support habitats necessary, at least in part, for the survival and successful maintenance of plant or animal species established under state or federal law as rare, threatened or endangered. MAR —Marine Habitat: Includes uses of water that support marine ecosystems including, but not limited to, preservation or enhancement or marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mammals, shorebirds). MIGR —Migration of Aquatic Organisms: Includes uses of water that support habitats necessary for migration, acclimatization between fresh and salt water, or other temporary activities by aquatic organisms, such as anadromous fish. SPWN - Spawning, Reproduction, and/or Early Development: Includes uses of water that support high quality aquatic habitats suitable for reproduction and early development of fish. This use is applicable only for the protection of anadromous fish. 3e. Summarize primary pollutants of concern The primary pollutants of concern for this project are sediment, nutrients, heavy metals, organic compounds, trash & debris, oxygen demanding substances, oil & grease, bacteria & viruses, and pesticides. The extensive use of bioretention treatment control facilities throughout the site should be a 6 I:U3 I020\Stormwater_Site\SWMP\I3I020.SWMP.doc Lot 17 - Carlsbad Raceway Business Park highly effective method of treating coarse sediment and trash, and pollutants that tend to associate with fine particles during treatment. Bioretention facilities also show medium effectiveness for treatment of pollutants that tend to be dissolved following treatment. I:\I3 I020\Stormwater_SiteSWMP\13I020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 4. SOURCE CONTROL MEASURES 4a. Description of site activities and potential sources of pollutants Activities and potential pollutant sources associated with this site include: On-site storm drain inlets Interior floor drains Landscape and outdoor pesticide use Refuse areas Loading docks Fire sprinkler test water Miscellaneous drain or wash water consisting of: Boiler drain lines. Condensate drain lines Rooftop equipment Drainage sumps Roofing, gutters, and trim Plazas, sidewalks, and parking lots 4b. Stormwater Pollutant Sources and Source Controls The following table identifies permanent and operational source control measures for the project site as outlined in Appendix 1, Stormwater Pollutant Sources and Source Control checklist in the City's SUSMP: Potential Source of Runoff Pollutants Permanent Source Control BMPs Operational Source Control BMPs On-Site Storm Drain Mark all inlets with the words "No Dumping! Flows to Maintain and periodically repaint or Inlets Bay or similar. replace Inlet markings. Provide stormwater pollution prevention information to site owners, lessees, or operators. See applicable operational BMPs In • Fact Sheet SC-44, "Drainage System Maintenance," in the CASQ.A Stormwater Quality Handbooks at www.cabmphandbooks.com Include the following in lease agreements: "Tenant shall not allow anyone to discharge anything to storm drains or to store or deposit materials so as to create a potential discharge to storm drains." Provide stormwater pollution prevention information to site owners, lessees, or operators. Landscape and Final landscape plans will accomplish all of the following: Maintain landscaping using minimum Outdoor Pesticide Use Preserve existing native trees, shrubs, and ground or no pesticides. 8 l:\I3lO2O\StormwaterSite\SWMP\I31O2O-SWMP.doc Lot 17 - Carlsbad Raceway Business Park Potential Source of Runoff Pollutants Permanent Source Control BMPs Operational Source Control BMPs cover to the maximum extent possible. See applicable operational BMPs In Design landscaping to minimize irrigation and runoff Fact Sheet SC-41, "Building and, to promote surface infiltration where appropriate, and a Grounds Maintenance," in the CASQA to minimize the use of fertilizers and pesticides that Stormwater Quality Handbooks at can contribute to stormwater pollution. www.cabmphandbooks.com Where landscaped areas are used to retain or detain Provide IPM information to new stormwater, specify plants that are tolerant of owners, lessees and operators. saturated soil conditions. Consider using pest-resistant plants, especially adjacent to hardscape. To insure successful establishment, select plants appropriate to site soils, slopes, climate, sun, wind, rain, land use, air movement, ecological consistency, and plant interactions. Refuse Areas ' State that signs will be posted on or near dumpsters Provide adequate number of with the words "Do not dump hazardous materials receptacles. Inspect receptacles here" or simIlar, regularly; repair or replace leaky receptacles. Keep receptacles covered. Prohibit/prevent dumping of liquid or hazardous wastes. Post "no hazardous materials" signs. Inspect and pick up litter daily and clean up spills Immediately. Keep spill control materials available on-site. See Fact Sheet SC-34, "Waste Handling and Disposal" in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Outdoor Storage of Include a detailed description of materials to be See the Fact Sheets SC-31, "Outdoor Equipment or stored, storage areas, and structural features to Liquid Container Storage" and SC-33, Materials, prevent pollutants from entering storm drains. "Outdoor Storage of Raw Materials" Where appropriate, reference documentation and in the CASQA Stormwater Quality Handbooks compliance with the requirements of local Hazardous at Materials Programs for: www.cabmohandbopks.com Hazardous Waste Generation Hazardous Materials Release Response and Inventory California Accidental Release (CalARP) Aboveground Storage Tank Uniform Fire Code Article 80 Section 103(b) & (c) 1991 Underground Storage Tank Loading Docks Blo-clean trench drain Insert to be Installed in each Move loaded and unloaded items loading dock trench drain, indoors as soon as possible. J:\13 1020\Stonnwater_Site\SWMPI3I020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park Potential Source of Runoff Pollutants Permanent Source Control BMPs Operational Source Control BMPs See Fact Sheet SC-30, "Outdoor Loading and Unloading," in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Fire Sprinkler Test Obtain a permit from the City of Carlsbad to provide a See the note in Fact Sheet SC-41, Water means to drain fire sprinkler test water to the sanitary "Building and Grounds Maintenance," sewer. in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com Miscellaneous Drain Boiler drain lines shall be directly or indirectly or Wash Water: connected to the sanitary sewer system and may not Boiler drain lines discharge to the storm drain system. Condensate drain Condensate drain lines may discharge to landscaped lines areas if the flow is small enough that runoff will not occur. Condensate drain lines may not discharge to Rooftop equipment the storm drain system. Drainage sumps Rooftop mounted equipment with potential to produce pollutants shall be roofed and/or have Roofing, gutters, secondary containment. and trim Any drainage sumps on-site shall feature a sediment sump to reduce the quantity of sediment in pumped water. Avoid roofing, gutters, and trim made of copper or other unprotected metals that may leach into runoff. Sidewalk and Parking Sidewalks and parking lots shall be Lots 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. Permeable Payers See Fact Sheet SD-20, "Pervious Pavements," in the CASQA Stormwater Quality Handbooks at www.cabmphandbooks.com 10 i:\131O2OStormwaterSite\SWMP\I3IO2O-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP S. LOW IMPACT DEVELOPMENT (LID) DESIGN STRATEGIES The LID strategies applicable to this commercial development project include dispersing runoff to adjacent pervious surfaces and draining to Integrated Management Practices (IMPs). The entire site has been divided into four drainage areas comprising of discrete Drainage Management Areas (DMAs) based on surface type. These areas were used to determine which LID strategy alternative best applies to that specific drainage area. The Integrated Management Practice (IMP) approach was used on four DMAs to meet both treatment and/or hydromodification flow control objectives. See Section 8 for further hydromodification design. Attachment 2, BMP and DMA Exhibit, depicts each of these strategies and locations of treatment, hydromodification and flow-control facilities. 11 I:\I3 I020\Stormwater_Site\SWMP\I3I020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 6. INTEGRATED MANAGEMENT PRACTICES (IMP'S) 6a. Selection process for IMP's According to Table 2-2 of the SUSMP, the majority of pollutants of concern for this project can be grouped in the category of pollutants that tend to associate with fine particles during treatment. Nutrients also fall under the category of pollutants that tend to be dissolved following treatment and trash & debris falls under the category of coarse sediment and trash. According to Table 2-3,infiltration facilities provide the highest effectiveness for removal of pollutants in all three categories, but the site is constrained by impermeable soils. Bioretention facilities were chosen extensively throughout the site for their high removal rates of coarse sediment and trash and pollutants that tend to associate with fine particles during treatment and their medium removal rates for Pollutants that tend to be dissolved following treatment. Bioretention facilities detain stormwater and filter it slowly through engineered soil or sand and are versatile in that they can be any shape and can be landscaped. The bioretention areas onsite were siizedto treat stormwater and/or limit flow using control through hydromodification. 6b. Sizing factors for IMP's Threshold Determination The downstream receiving water channel was not assessed, therefore, according to Figure 2-2 of the City's SUSMP, the site must mitigate peak flows and durations based on a pre-project condition lower flow threshold of O.1Q2. HMP Decision Matrix IMP facilities were sized using the Decision Matrices in Figures 2-2 in Section 8, hydromodification. 6c. Geotechnical recommendation on soil infiltration rates IMP facilities were chosen that do not drain through native soil, as soil infiltration rates were anticipated to be low. 6d. Infiltration calculations Self-retaining areas were not utilized on this site, as soil infiltration rates were anticipated to be low. 12 I:\I3IO2O\Stormwater_Site\SWMP\I3IO2O.SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 7. TREATMENT CONTROL BMP's Water quality treatment will be accomplished through the use of bioretention facilities, an Urban GreenO unit, and Bio Clean° trench drain inserts. Bioretention basin areas were sized for both treatment and hydromodification. See PIP for details and specifications for bioretention basins (Attachment 5). Urban GreenO unit details and specifications are in Attachment 4. Bio Clean® trench drain insert details and specifications are in Attachment 6. 13 I:\131020\Stormwater_Site\SWMP\I3I020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 8. HYDROMODIFICATION 8a. Threshold Determination Field investigations were not conducted pursuant to SCCWRP screening tools. Therefore, according to Figure 2-2 below, the site must mitigate peak flows and durations based on a pre- project condition lower flow threshold of 0.102. Got 1. Project using YES SCCWRP Figure 6.4 of the Screening Tools? M Mat atnx NO TES Consult with NO 3. Has eolech Conf med j YES and MP Facilities br - Flow Range 0.101001 ? . Redesign NO Drawdo vn LID or BMP Requi ments YES End of F Matrix ecislan FIGURE 2-2. Mitigation Criteria and Implementation 14 1:13I020\Stonnwater_Site\SWMP\131020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park Continuous Simulation Model A continuous simulation model (Storm Water Management Mode - SWMM) is being utilized to simulate runoff quantity and quality from Lot 17. 8c. Tabulation of Flow-control Facility Sizes and Design Criteria The Storm Water Management Model (SWMM) program hydrology and conveyance system hydraulics software was used to simulation single event or long-term (continuous) simulation of runoff quantity and quality from primarily urban areas. See Attachment 3 for SWMM report results. See PIP for details and specifications for bioretention basins. 15 1:\I31020\StormwatcrSite\SWMP\I3I020-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 9. DOCUMENTATION OF STORM WATER DESIGN Hydrology maps Attachment 2, BMP and DMA Plan Exhibit, depicts the treatment controls, low impact design, source control BMPs, and boundaries of each drainage area draining to each IMP. SWMM LID BMP Sizing Attachment 3 includes the SWMM Results for each IMP considered. The report calculates the plan area, ponding volume, storage volume, and orifice flow and size for each IMP considered. 16 I:\i31020\Stormwater_Site\SWMP\I3IO2O-SWMP.doc Lot 17 - Carlsbad Raceway Business Park SWMP 10. BMP FACILITY MAINTENANCE REQUIREMENTS 10a. Ownership and responsibility of maintenance of BMP's The Owner and Developer will be responsible for the maintenance of treatment facilities. Ongoing maintenance will be assured by executing a Permanent Stormwater Quality BMP Maintenance Agreement that "runs with the land." lOb. Summary of maintenance requirements Bioretention facilities remove pollutants primarily by filtering runoff slowly through aerobic, biologically active soil. Routine maintenance is needed to ensure that flow is unobstructed, that erosion is prevented, and that soils are held together by plant roots and are biologically active. Typical maintenance consists of the following: Inspect inlets for channels, exposure of soils, or other evidence of erosion. Clear any obstructions and remove any accumulation of sediment. Examine rock or other material used as a splash pad and replenish if necessary. . Inspect outlets for erosion or plugging. . Inspect side slopes for evidence of instability or erosion and correct as necessary. Observe the surface of bioretention facility soil for uniform percolation throughout. If portions of the bioretention facility do not drain within 24 hours after the end of a storm, the soil should be tilled and replanted. Remove any debris or accumulations of sediment. Confirm that check dams and flow spreaders are in place and level and that rivulets and channelization are effectively prevented. Examine the vegetation to ensure that it is healthy and dense enough to provide filtering and to protect soils from erosion. Replenish mulch as necessary, remove fallen leaves and debris, prune large shrubs or trees, and mow turf areas. When mowing, remove no more than 1/3 height of grasses. Confirm that irrigation is adequate and not excessive and that sprays do not directly enter overflow grates. Replace dead plants and remove noxious and invasive vegetation. Abate any potential vectors by filling holes in the ground in and around the bioretention facility and by insuring that there are no areas where water stands longer than 48 hours following a storm. If mosquito larvae are present and persistent, contact the San Diego County Vector Control Program for information and advice. Mosquito larvicides should be applied only when absolutely necessary and then only by a licensed individual or contractor. 17 I:\I 3I020\Stormwater_SiteSWMP\13I020-SWMP.doc Lot 17- Carlsbad Raceway Business Park SWMP 11. SWMP CERTIFICATION STATEMENTS ha. Preparer's statement The selection, sizing, and preliminary design of stormwater treatment and other control measures in this plan meet the requirements of Regional Quality Control Board Order 119-2007-0001 and subsequent amendments. NAME 6ATE hib. Owner's statement The selection, sizing, and preliminary design of stormwater treatment and other control measures in this plan meet the requirements of Regional Quality Control Board Order 119-2007-0001 and subsequent amendments. II) / / ATE 18 I:13I020SIormwaterShc%SWMPI31020-SWMP4oc ATTACHMENT 1 STORM WATER STANDARDS QUESTIONNAIRE 4 ^A, 4k CITY OF CARLSBAD STORM WATER COMPLIANCE FORM - TIER 3 CONSTRUCTION SWPPP E-31 Development Services Land Development Engineering 1635 Faraday Avenue 7606022750 www.carlsbadca.gov I am applying to the City of Carlsbad for the following type of construction permit(s): Grading Permit 0 Building Permit 0 Right-of-Way Permit My project requires preparation and approval of a Tier 3 Construction Storm Water Pollution Prevention Plan (SWPPP) because my project meets one or more of the following criteria demonstrating that the project potentially poses a significant threat to storm water quality: My project includes clearing, grading or other disturbances to the ground resulting In soil disturbance totaling one or more acres including any associated construction staging, equipment storage, stockpiling, pavement removal, refueling and maintenance areas; or, 0 My project is part of a phased development plan that will cumulatively result in soil disturbance totaling one or more acres including any associated construction staging, equipment storage, stockpiling, pavement removal, refueling and maintenance areas; or, U My project is located inside or within 200 feet of an environmentally sensitive area and has a significant potential for contributing pollutants to nearby receiving waters by way of storm water runoff or non-storm water discharge(s). I CERTIFY TO THE BEST OF MY KNOWLEDGE THAT THE ABOVE CHECKED STATEMENTS ARE TRUE AND CORRECT. I AM SUBMITTING FOR CITY APPROVAL A TIER 3 CONSTRUCTION SWPPP PREPARED IN ACCORDANCE WITH CITY STANDARDS AND THE REQUIREMENTS OF THE STATE WATER RESOURCES CONTROL BOARD GENERAL PERMIT FOR CONSTRUCTION ACTIVITIES - WATER QUALITY ORDER NO 99108-DWQ OR ORDER NO. 2009-0009 - DWQ AFTER JULY 1, 2010, (GENERAL CONSTRUCTION PERMIT) AND ANY AMENDMENT, REVISION OR RE- ISSUANCE THEREOF. I UNDERSTAND AND ACKNOWLEDGE THAT I MUST SUBMIT THE CITY APPROVED TIER 3 CONSTRUCTION SWPPP TO THE SAN DIEGO REGIONAL WATER QUALITY CONTROL BOARD TOGETHER WITH A NOTICE OF INTENTION (NOI), AN APPROPRIATE FILING FEE AND OTHER REQUIRED DOCUMENTATION AND RECEIVE A STATE WASTE DISCHARGER'S IDENTIFICATION (WDID) NUMBER PRIOR TO CITY ISSUANCE OF THE ABOVE REQUESTED CONSTRUCTION PERMIT(S). I ALSO UNDERSTAND AND ACKNOWLEDGE THAT I MUST ADHERE TO, AND AT ALL TIMES, COMPLY WITH THE CITY APPROVED TIER 3 CONSTRUCTION SWPPP THROUGHOUT THE DURATION OF THE CONSTRUCTION ACTIVITIES UNTIL THE CONSTRUCTION WORK IS COMPLETE AND APPROVED BY THE CITY OF CARLSBAD. I 22.1-8I- E-31 Page 1 of 1 REV 4130110 CITY OF CAIRLS11 AD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov I INSTRUCTIONS: I 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 (BMP's) into the project design per the City's Standard Urban Stormwater Management Plan (SUSMP). To view the SUSMP, refer to the Engineering Standards (Volume 4, Chapter 2) at www.caflsbpdca.gov/standards. 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 to additional criteria called 'Priority Development Project Requirements'. Many aspects of project site design are dependent upon the storm water standards applied to a project. Your 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 you, 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 you are unsure about the meaning of a question or need help In determining how to respond to one or more of the questions, please 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, you must also complete, sign and submit a Project Threat Assessment Form with construction permits for the project. Please start by completing Step I and follow the Instructions. When completed, sign the lbmi at the end and submit this with your application to the city. STEP 11' TOBE COMPLETED FOR ALL PROJECTS To determine if your project is a priority development project, please answer the following questions: YES NO Is your project LIMITED TO constructing new or retrofitting paved sidewalks, bicycle lanes or trails that meet the following criteria: (1) Designed and constructed to direct storm water runoff to adjacent vegetated areas, or other non-erodible permeable areas; OR (2) designed and constructed to be hydraulically disconnected from paved streets or roads; OR (3) designed and constructed with permeable pavements or surfaces In accordance with USEPA Green Streets guidance? Is your project LIMITED TO retrofitting or redeveloping existing paved alleys, streets, or roads that are designed and constructed in accordance with the USEPA Green Streets guidance? If you answered yes to one or more of the above questions, then your project is NOT a priority development project and therefore is NOT subject to the storm water criteria required for priority development projects. Go to step 4, mark the last box stating "my project does not meet POP requirements" and complete applicant Information. if you answered -ne to both questions, then go to Step 2. E-34 Page 1 of 3 Effective 6/27/13 CITY OF CAR LSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue 160-602-2750 www.carlsbadca.gov STEP 2 TO BE COMPLETED FOR ALL NEW OR REDEVELOPMENT PROJECTS To determine if your project is a priority development project, please answer the following questions: YES NO is your project a new development that creates 10,000 square feet or more of impervious surfaces collectively over the entire project site? This includes commercial, Industrial, residential, mixed-use, and public development projects on public or private land. Is your project creating or replacing 5.000 square feet or more of Impervious surface collectively over the entire project site on an existing site of 10,000 square feet or more of impervious surface? This includes commercial, industrial, public development projects on public or private land. _residential, _mixed-use,_and Is your project a new or redevelopment project that creates 5,000 square feet or more of Impervious surface collectively over the entire project site and supports a restaurant? A restaurant is a facility that sells prepared foods and drinks for consumption, Including stationary lunch counters and refreshment stands selling prepared foods and drinks for immediate consumption. Is your project a new or redevelopment project that creates 5,000 square feet or more of Impervious surface collectively over the entire project site and supports a hillside development project? A hillside development project Includes development on any natural slope that Is twenty-five percent or greater. S. Is your project a new or redevelopment project that creates 5,000 square feat or more of impervious surface collectively over the entire project site and supports a parking lot. A parking lot Is land area or facility for the temporary parking or storage of motor vehicles used personally for business or for commerce. Is your project a new or redevelopment project that creates 5.000 square feet or more of impervious surface collectively over the entire project Site and supports a street, road, highway freeway or driveway? A street, road, highway, freeway or driveway is any paved Impervious surface used for the transportation of automobiles, trucks, motorcycles, and other vehicles. Is your project a new or redevelopment project that creates or replaces 2,500 square feet or more of impervious surface collectively over the entire site, and discharges directly to an Environmentally Sensitive Area (ESA)?'Discharging Directly to' includes flow that is conveyed overland a distance of 200 feet or less from the project to the ESA, or conveyed In a pipe or open channel any distance as an isolated flow from the project to the ESA commingles with flows from adjacent lands). ct _(Fe._not Is your project a new development that supports an automotive repair shop? An automotive repair shop is a facility that Is categorized In any one of the following Standard Industrial Classification (SIC) codes: 5013, )( 5014, 5541, 7532-7534, or 7536-7539. Is your project a new development that supports a retail gasoline outlet (RGO)? This category includes RGO's that meet the following criteria: (a) 5,000 square feet or more or (b) a project Average Daily Traffic (AOl) of 100 or more vehicles per day. Is your project a new or redevelopment project that results in the disturbance of one or more acres of land and are expected to generate pollutants post construction? Is your project located within 200 feet of the Pacific Ocean and (1) creates 2,500 square feet or more of Impervious surface or (2) Increases surface on the by more than _impervious _property _10%? If you answered "yes" to one or more of the above questions, you ARE a priority development project and are therefore subject to Implementing structural Best Management Practices (BMP's) in addition to Implementing Standard Storm Water Requirements such as source control and low impact development BMP's. A Storm Water Management Plan (SWMP) must be submitted with your application(s) for development. Go to step 3 for redevelopment projects. For new projects, go to step 4 at the end of this questionnaire, check the "my project meets PDP requirements" box and complete applicant Information. If you answered "no" to all of the above questions, you ARE NOT a priority development project and are therefore subject to implementing only Standard Storm Water Requirements such as source control and low Impact development BMP's required for all development projects. A Storm Water Management Plan (SWMP) is not required with your application(s) for development. Go to stop I at the and of this questionnaire, check the "my project does not meet PDP requirements" box and complete applicant Information. E-34 Page 2of3 Effective 0127113 CITY OF CARLSBAD STORM WATER STANDARDS QUESTIONNAIRE E-34 Development Services Land Development Engineering 1635 Faraday Avenue 760-602-2750 www.carlsbadca.gov ONLY. Does the redevelopment project result in the creation or replacement of impervious surface In an amount of less than 50% of the surface area of the previously existing development? If you answered "yes, the structural BMP's required for Priority Development Projects apply only to the creation or replacement of Impervious surface and not the entire development. Go to step 4, chock the "my project meets POP requirements" box and complete applicant Information. If you answered no, the structural BMP's required for Priority Development Projects apply to the entire development. Go to step 4, - - CHECK THE-APPROPRIATE BOX AND-COMPLETE APPLICANT* INFORMATION - My project meats PRIORITY DEVELOPMENT PROJECT (POP) requirements and must comply with additional stomiwater criteria per the SUSMP and I understand I must prepare a Storm Water Management Plan for submittal at time of application. I understand flow control (hydromodiflcation) requirements may apply to my project. Refer to SUSMP for details. 0 My project does not meet POP requirements and must only comply with STANDARD STORMWATER REQUIREMENTS per the SUSMP. As part of these requirements, I will incorporate low impact development strategies throughout my project. Applicant Information and Signature Box Address: L,og. %(.r,C -tkioo Applicant Name: AccessoY ner(s3f Applicant Title: (cck- 4ci4rre.. Date: (1 I This Box for City Use Only * Environmentally Sensitive Areas include but are not limited to all Clean Water Act Section 303(d) Impaired 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 quivalent 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. E-34 Page 3 of 3 EffectIve 8127/13 ATTACHMENT 2 BMP AND DMA PLAN EXHIBIT L - A LLS ' 4 / ivc 'o is b ) ' çiL 10 VVF \ 1 ,) c W::l;: m rn t \ \L - U i - o ROW PROV Pi &V70 MWAX TH i TV T p - I 'I-' • \ ' 14 / r/ J':TT:;.:T T '— OV70 so If — ç P - \N'W i 11 ,// -' - \'\ / 'f -- .-----..H VifT - Rc4v-'- % c4JO3YJR ICE a- r \ I %i - 4SH P1t' — -. PRNN 77 DMA g CUP 1 -- '- e ......____ I ---- LP / 4.i.;LJ - 14 RFDAiiO0 ' PARCEL 'p4'Aar Sol" p1w aw TWO —STORY BUILD/NC LI.. — / s -- --: PRDOREC F.F. ELEV-398 00 r 1 285 * N 'FUNO I PAD ELEV.=397.25 -- -_ 5 — I SUER .4S...dthPJ?. DISWAROM - U -- ----/ D.__. 8LOgS&aOWmRkEDETA1FJ C SWAJES AND/OR RAIN GARDENS PRIOR TO - - ENIERING fl'E STORM DRAIN S11EM iva. awn man I --->- :.. .j --- .. ---- - I. -----. I 101 /Ih /D41 13 / mmm now m~ man offm mww(;~ mum wXw now mm - - Li $-h /1(:. - - S i -- I J I I 1 71 I JIL I - DIVA 2 ----P?5Dx'il - / - / Il.JC Ii /R I/IS I'I'I / — iflIr18±__ I 1 &V1CSfT4' - 5. 1 07 11 i'AD I 6' fi4l If ¼2 J910 J 4 PROPOSEP 'i - i t I I ORNN I * IN 6F CRAOiNG SII4WP NO. 14-05 I1'IA/NTENANcE AGREEIWENT DOC?JA.1EN1 YES-!— NO --- PARTY RESPONSIBLE FOR /vI,4INTENANc NAME BURKE REAL ESTATE GROUP CONTACT M/HAEL COADY ADDRESS. 260 £ BAKER STREET, SUITE 100 COSTA MESA, CA 92626 PHONE NO.: (714) 824-6014 PLAN PREPARED B) NAME- 11410 THY 0. CARROLL, /R. SIGNATURE COMPANY OVA Y CONSUL TAN) S INC. ADDRESS.' 2710 LOKER A VENUE KfST SUITE 100 CARLSBAD, CA 92010 PHONE NO.: 760-931-7700 CER11F/'A 17ON._ ) BA/P NOTES.' THESE BMPS ARE MANDATORY TO BE INSTALLED PER MANUFACTURER'S REGOMMENDA liONS OR THESE PLANS. NO CHANGES TO THE PROPOSED BMPS ON THIS SHEET V'1THOUT PRIOR APPROVAL FROM LAND DEVELOPMENT ENGINEERING. J. NO SUBSTITUTIONS TO THE MATERIAL. OR TYPES OR PLANTING TYPES KITHOUT PRIOR APPROVAL FROM LAND DEVELOPMENT ENGINEERING. NO OCCUPANCY flLL BE GRANTED UNTIL THE Cm' INSPECTION STAFF HAS INSPECTED THIS PROJECT FOR APPROPRIATE BMP CONSTRUCTION AND INSTALLATION. REFER TO MAINTENANCE AGREEMENT DOCUMENT. SEE PROJECT SV/MP FOR ADDITIONAL INFORMATION. DIVA SUik1/VARY DM4 1 =51. 4825F =1. 18A CONC/ASPH = 26,2425F = 0. 60,4 C ROOF = 18,483SF =0 36AC LANDSCAPING = 9, 7,575f = 0. 22A DMA2 _53 076SF =1.2/AC / OSj cONc/ASPH = 18,071SF = a 4/AC / -' -' - -- - ---- ROOF = 28,792SF = 059,4 C - - - LANDSCAPING = 9,213SF = 02/AC - - -- -L - A3Z ROAD - tEtY,r DIWA 3 =8/5405F=2.00AC " I CONC/ASPH =J2, 4925F = 0 75AC ---------- PER V/OIlS CONC/ASPH = 5,2005F = 0. 12A :HER FAMa'TFR ROOF = 34572SF = 0. 79A C - -I - LANDSCAPING = 18,2765F = 0. 35AC PIJRIJCWATLREA.M&vT-- ' DMA4 =4,618SF=01/AC P& DRECX - - -- - --. - - - - - - S - - - - CONC/ASPH = 2,435SF = 0. 06A C - - - -- - PER V/OIlS CONC/ASPH = 1,438SF = 0. OJA C -5-- - LANDSCAPING = Z 45SF = 0. 02A I?-. I6IS LEGEND D -SCRIP 11ON DMA AREA BOUNDARY, PROPOSED BOUNDARY. DMA AREA DESIGNA liON FLOW DIREC liON - SURFACE TYPE LANDSCAPING /4IPER 1401/S SURFACE. PERMEABLE PA frERS ROOF SYMBOL . — — — — — - .. DMA > -4- I_-_I / r zt PO/TD20'.IDE bt' U41ER EASEMENT DX__ / 40-0 2ø I-PROPOSED 1&11S 6F i 07' 15 JIM? NO I5C OFES 0. XU mg Uj - ........ h --,. EA1ST/8RCP5D-. 'J82 56 FL 18 1 31/a 2,0 IL (1, 0 CONSULT NTS 2710 Laker Ave West Civil Engineering Suite 100 Planning r'o Carlsbad, California 92010 Processing 760-931--7700 Surveying cD Fax: 760-931-8680 (N Oday@Odayconsultants.com BMP TABLE BMP TYPE SYMBOL ICASQA NO QUANTITY }DRAWING NO SHEET ND.(S INSPECTION j MAINTENANCE, CONSTRUCTION ID#FREQUENCY FREQUENCY SIGN—OFF HYDROMODIFICATION & TREATMENT CONTROL BIORETENTION TC-32 . 9,508 SF 482-5A 3 4 - B,FTER _NyLj'J SEMI-ANNUALLY ___________ STORM EVENT URBAN GREEN® FLOW THROUGH 1 EA 482-5A 4 SEMI-ANNUALLY & AFTER MAJOR ANNUALLY PLANTER MP-52 . STORM EVENT @ TRENCH BIOCLEAN® - SEMI-ANNUALLY ANNUALLY DRAIN "" 2 EA 482-5A 3 & AFTER MAJOR FIL TER STORM EVENT LOW-IMPACT DESIGN (L.I.D.) ROOF DRAIN TO LANDSCAPING -- - "Uj 'I -- 482-5A SEMI-ANNUALLY & AFTER MAJOR ANNUALLY - STORM EVENT SOURCE CONTROL 1 A .ON-SITE STORM DRAIN --- SD 13 c,-' A JU'ff 482-5A - SEMI-ANNUALLY & AFTER MAJOR - - INLETS - STORMEVENT 2 LANDSCAPE/ OUTDOOR 482-5A PESTICIDE USE A DRAINAGE A 482 SC 4 A SYSTEM -5A MAINTENANCE 4 EFFICIENT IRRIGATION SD 2 482-5A SEMI-ANNUALLY & AFTER MAJOR MONTHLY STORMEVENT /\ AREAS REFUSE SD-J2 - 34 2 482-5A - SEMI-ANNUALLY & AFTER MAJOR MONTHLY STORMEVENT /\ LOADING DOCKS -_ '' sJV 482-5A -z ' SEMI-ANNUALLY & AFTER MAJOR MON HL STORMEVENT A PERMEABLE PAVEMENT SD-20 - -- 482-5A SEMI-ANNUALLY & AFTER MAJOR ANNUALLY STORM EVENT I 6 N ! 71JL - \\ / 1 -12 iA1EfSl/(3 5- - \ I' (- !i1 :---.— --: -: EXIST 8PL'C -- __O_ - ------- -L CITY OF CARLSBAD SHEETS ENGINEERINGDEPARTMENT 1 BMP AM) DMA PLAN EXHIBIT LOT 17 CARLSBAD RA CEWA Y fiLlS/NESS PARK RECORD COPY INITIAL DATE PROJECT NO. S.D.P. 14-01 DATE INITIAL REVISION DESCRIPTION DATE INITIAL DATE INITIAL I DRAWING NO. L ENGINEER OF WORK OTHER APPROVAL CITY APPROVAL I: \131020\StormwaterSite\SwMP\1320—sWMP—Gpdwg Jul 14, 2014 2:35pm Xrefs: 1320AMAP; 1320AGRD; 1320AUTL; 1320A0—TXT; 1320PIP; 1320TP01 ATTACHMENT 3 SWMM PROGRAM RESULTS TECHNICAL MEMORANDUM: SWMM Modeling for Hydromodification Compliance of: Carlsbad Raceway Lot 17 Prepared for: Burke Real Estate Group September 9, 2013 Prepared by: Luis P rra, PhD, CPSWQ, ToR, D.WRE. I R.C.E. 66377 No. 66377 L1 *\ExP. 8-30-2014J TORY R. WALKER ENGINEERING,, INC. WATER RESOURCES PLANNING & ENGINEERING 122 Civic CENTER DRIVE. SuITE 206, VIsTA, CA 92084 PH:760-414.9212 WWW.TRWENGINEERING.COM I TORY R. WALKER ENGINEERING, INC. WATER RESOURCES PLANNING & ENGINEERING TECHNICAL MEMORANDUM TO: Burke Real Estate Group FROM: Tory Walker, PE, CFM, LEED GA Luis Parra, PhD, PE, CPSWQ. 1, D.WRE. DATE: September 9, 2013 RE: Summary of SWMM Modeling for Hydromodification Compliance for Carlsbad Raceway Lot 17, Carlsbad, CA. INTRODUCTION This memorandum summarizes the approach used to model the proposed commercial development project site in the City of Carlsbad using the Environmental Protection Agency (EPA) Storm Water Management Model 5.0 (SWMM). SWMM models were prepared for the pre and post-developed conditions at the site in order to determine if the proposed LID bioretention facilities have sufficient volume to meet the current Hydromodificatión Management Plan (HMP) requirements from the San Diego Regional Water Quality Control Board (SDRWQCB). SWMM MODEL DEVELOPMENT The Carlsbad Raceway Lot 17 project proposes a commercial building on the currently vacant property, with servicing parking lot and a receiving dock. Two (2) SWMM models were prepared for this study: the first for the pre-development and the second for the post-developed conditions. The project site drains to one (1) Point of Compliance (POC) located to the north-west of the project site located at an existing storm drain outlet draining to a natural channel. Regarding SWMM, it was used since we have found it to be more comparable to San Diego area watersheds than the alternative San Diego Hydrology Model (SDHM). For both SWMM models, flow duration curves were prepared to determine if the proposed HMP facility is sufficient to meet the current HMP requirements. The inputs required to develop SWMM models include rainfall, watershed characteristics, and BMP configurations. The Oceanside Gage from the Project Clean Water website was used for this study, since it is the most representative of the project site precipitation due to elevation and proximity to the project site. Evaporation for the site was modeled using average monthly values from the County hourly dataset. The site was modeled as with Type 0 hydrologic soil as this is the existing soil determined from the 2003 County of San Diego Hydrology Manual. Soils have been assumed to be compacted in the existing condition to represent the current mass graded condition of the site, while fully compacted in the post developed conditions. Other SWMM inputs for the subareas are discussed in the appendices to this document, where the selection of the parameters is explained in detail. 122 Civic CENTER DRIVE, SUITE 206, VISTA, CA 92084 1 PH: 760.414.9212 FX 760.414.9277 1 WWW.TRWENGINEERING.COM Carlsbad Raceway Lot 17 HMP Memo September 9, 2013 HMP MODELING DEVELOPED CONDITIONS Storm water runoff from the proposed project site is routed to a single POC located to the northwest of the project site. Runoff from the developed project site is drained to four (4) onsite receiving bioretention LID BMPs. Once flows are routed via the proposed LID BMPs, all flows are then conveyed via storm drain to the aforementioned POC. In accordance with water quality design criteria, a portion of the project site consisting of approximate 6,000 square feet of impervious loading dock areas do not drain to the bio-retention LID BMPs and are confluence directly at the POC. It is assumed all storm water quality requirements for the project will be met by the bioretention LID BMPs (as the minimum required treatment footprint area is met by the proposed BMP design). However, detailed water quality requirements are not discussed -within this technical memo. For further information in regards to storm water quality requirements for the project, please refer to the site specific Storm Water Management Plan (SWMP). TABLE 1— SUMMARY OF DEVELOPED CONDITIONS WQ 85th PercentlIe11 DMA 1. Tributary Area, A (Ac) 2 Impervious' Percentage, Ip Slope Area Required Area Provided (ft2) (ft2) DMA 1 0.564 70.96% 1% 734 2,016 DMA 2 1.347 90.58% 1% 2,166 4,489 DMA 3 2.323 81.32% 1% 3,381 3,462 DMA 4(3) 0.110 81.82% 1% NA NA J.,; 0J pu.eI1LIIe requlru d1d corresponas to approximateuy 4b Wine impervious area plus 0.4% ot the pervious area draining to the IMP (simplified SUSMP equation) IMP Areas are subtracted from the overall DMA to ensure areas are not double counted. BMP provided is not a bioretention basin rather a proprietary Contech Bioretention BMP vault system sized to provide sufficient treatment for the 85th percentile flow. Three (3) LID bioretention basins are located within the project site and are responsible for handling hydromodification requirements for the majority of the project site. A small 0.11 acre portion of the southwestern parking lot drains to a proprietary Contech bioretention vault prior to discharging to the POC. This vault has been modeled within the SWMM model for developed conditions using the vault footprint area provided for bio retention treatment and a media filtration rate of 100-inches/hr (representative of the treatment media within the vault). In developed conditions, the basins will have a surface depth of 1.32 to 1.4 feet and a riser spillway structure (see dimensions in Table 2). Flows will then discharge from the basins via a low flow orifice outlet within the gravel layer. The riser structure will act as a spillway such that peak flows can be safely discharged to the receiving storm drain system. Regarding ponding elevations, table 3 on the following page illustrates the respective top, bottom and riser elevations accordingly. 2 W.0.313-1 Carlsbad Raceway Lot 17 HMP Memo September 9, 2013 Beneath the basins' invert lies the proposed LID bioretention portion of the drainage facility. This portion of the basin is comprised of a 3-inch layer of mulch, a 24-inch layer of amended soil (a highly sandy, organic rich composite with an infiltration capacity of at least 5 inches/hr) and a 6-inch layer of gravel for additional detention and to accommodate the French drain systems. These systems are to be located beneath the bioretention layers to intercept treated storm water and convey these flows to a small diameter lower outlet orifice. Once flows have been routed by the outlet structure, flows are then discharged to the receiving POC discharge location. The bioretention basins were modeled using the bioretention LID module within SWMM. The bioretention module can model the underground gravel storage layer, underdrain with an orifice plate, amended soil layer, and a surface storage pond up to the elevation of the invert of the spillway. It should be noted that detailed outlet structure locations and elevations will be shown on the construction plans based on the recommendations of this study. BMP MODELING FOR HMP PURPOSES Modeling of dual purpose Water Quality/HMP BMPs Four (4) LID BMP bioretention basins are proposed for water quality treatment and hydromodification conformance for the project site. Table 2 illustrates the dimensions required for HMP compliance according to the SWMM model that was undertaken for the project. TABLE 2— SUMMARY OF DEVELOPED DUAL PURPOSE BMPS: DIMENSIONS Impervious Areat, Gravel Depth(z) Lower Orif. Depth Riser Riser Perimeter Total Surface BMP Tributary Area (Ac) (ft) (in) D (in)13 Invert (in)141 Length (ft) Depth(s) (in) 1 0.400 2,016 6 1.25 10 12 15.8 2 1.220 4,489 6 1.50 10 12 16.8 3 1.889 3,462 6 1.75 10 12 16.8 4 0.090 17 6 0.75 6 NA 36 Notes: (1): Area of amended soil equal to area of gravel Gravel depth needed to comply with hydromodification purposes Diameter of orifice in gravel layer with invert at bottom of layer; tied with hydromod min threshold (0.1.02). Depth of ponding beneath riser structure's surface spillway. Overflow length, the internal perimeter of the riser is 12 ft (3 ft x 3 ft Internal dimensions). Total surface depth of BMP from top crest elevation to surface invert. 3 W.0.313-1 Carlsbad Raceway Lot 17 HMP Memo September 9, 2013 TABLE 3—SUMMARY OF 810 RETENTION BASINS RELATIVE ELEVATIONS: BMP Basin Surface Elevation (ft) Riser Elevation (ft) Basin Top Elevation (ft) 1 395.00 395.83 396.32 2 393.30 394.13 394.70 3. 392.20 393.03 393.60 FLOW DURATION CURVE COMPARISON The Flow Duration Curve (FDC) for the site was compared at the POC by exporting the hourly runoff time series results from SWMM to a spreadsheet. The FDC was compared between 10% of the existing condition 0.2 up to the existing condition Q10. The Qi and Q10 were determined with a partial duration statistical analysis of the runoff time series in an Excel spreadsheet using the Cunnane plotting position method (which is the preferred plotting methodology in the HMP Permit). As the SWMM Model includes a statistical analysis based on the Weibull Plotting Position Method, the Weibull Method was also used within the spreadsheet to ensure that the results were similar to those obtained by the SWMM Model. The range between 10% of 0.2 and 0.10 was divided into 100 equal time intervals; the number of hours that each flow rate was exceeded was counted from the hourly series. Additionally, the intermediate peaks with a return period "i" were obtained (Q1 with i=3 to 9). For the-purpose of the plot, the values were presented as percentage of time exceeded for each flow rate. FDC comparison at the POC is illustrated in Figure 1 in both normal and logarithmic scale. Attachment 5 provides a detailed drainage exhibit for the post-developed condition. As can be seen in Figure 1, the FDC for the proposed condition with the HMP BMPs is within 110% of the curve for the existing condition in both peak flows and durations. The additional runoff volume generated from developing the site will be released to the existing point of discharge at a flow rate below the 10% 0.2 lower threshold. Additionally, the project will also not increase peak flow rates between the 02 and the 0.10, as shown in the graphic and also in the peak flow tables in Attachment 1. SUMMARY This study has demonstrated that the proposed and interim HMP BMPs provided for the Carlsbad Raceway Lot 17 site is sufficient to meet the current HMP criteria if the cross-section areas and volumes recommended within this technical memorandum, and the respective orifices and outlet structures are incorporated as specified within the proposed project site. KEY ASSUMPTIONS 1. Type 0 Soil is representative of the existing condition site. 4 W.0.313-1 Carlsbad Raceway Lot 17 HMP Memo September 9, 2013 ATTACHMENTS 02 to Q10 Comparison Tables FDC Plots (log and natural "x" scale) and Flow Duration Table. List of the "n" largest Peaks: Pre-Development and Post-Development Conditions Elevation vs. Area Curves and Elevations vs. Discharge Curves to be used in SWMM S. Pre & Post Development Maps, Project plan and section sketches SWMM Input Data in Input Format (Existing and Proposed Models) SWMM Screens and Explanation of Significant Variables Soil Map Summary files from the SWMM Model 5 W.0.313-1 Carlsbad Raceway Lot 17 HMP Memo September 9, 2013 ATTACHMENT 1. 0.2 to Q10 Comparison Table - POC 1 Return Period Existing Condition (cfs) Mitigated Condition (cfs) Reduction Exist - Mitigated (ds) 2-year. 2.386 1.436 0.950 3-year 2.717 1.601 1.116 4-year 3.079 1.909 1.170 5-year 3.126 2.157 0.969 6-year 3.226 2.348 0:878 7-year 3.420 2.471 0.949 8-year 3.516 2.682 0.834 9-year 3.676 2.782 0.894 10-year 3.873 2.793 1.080 W.O.313-1 ATTACHMENT 2 FLOW DURATION CURVE ANALYSIS 1) Flow duration curve shall not exceed the existing conditions by more than 10%, neither in peak flow nor duration. The figures on the following pages illustrate that the flow duration curve in post-development conditions after the proposed BMP is below the existing flow duration curve. The flow duration curve table following the curve shows that if the interval 0.10Q2 - CLo is divided in 100 sub- intervals, then a) the post development divided by pre-development durations are never larger than 110% (the permit allows up to 110%); and b) there are no more than 10 intervals in the range 101%-110% which would imply an excess over 10% of the length of the curve (the permit allows less than 10% of excesses measured as 101-110%). Consequently, the design passes the hydromodification test. It is important to note that the flow duration curve can be expressed in the "x" axis as percentage of time, hours per year, total number of hours, or any other similar time variable. As those variables only differ by a multiplying constant, their plot in logarithmic scale is going to look exactly the same, and compliance can be observed regardless of the variable selected. However, in order to satisfy the City of Carlsbad HMP example, % of time exceeded is the variable of choice in the flow duration curve. The selection of a logarithmic scale in lieu of the normal scale is preferred, as differences between the pre-development and post-development curves can be seen more clearly in the entire range of analysis. Both graphics are presented just to prove the difference. In terms of the "y" axis, the peak flow value is the variable of choice. As an additional analysis performed by TRWE, not only the range of analysis is clearly depicted (10% of Q2 to Q10) but also all intermediate flows are shown (Q2, Q3, Q4, Q3, 05, Q, Q8 and 05) in order to demonstrate compliance at any range Q - 03(+1. It must be pointed out that one of the limitations of both the SWMM and SDHM models is that the intermediate analysis is not performed (to obtain Q1 from = 2 to 10). TRWE performed the analysis using the Cunnane Plotting position Method (the preferred method in the HMP permit) from the "n" largest independent peak flows obtained from the continuous time series. The largest "n" peak flows are attached in this appendix, as well as the values of Q with a return period '1", from i=2 to 10. The Q values are also added into the flow-duration plot. Raceway 17- Flow Duration Curve 4.00 2.00 . a 0.001 0.01 0.1 Percentage of time exceeded (%) TT :rI:JI:::xIFr...... - "r"1 97i ....... 97i Ct ..... 1T rT Tf " r1 r 17 3.00 Cti -- --------- ------ Q2_ Qz IIr\ I I [ Existing --Proposed I -- QX 1.00 ................. ------ ------ I ---r---k-- t 0.00 I Raceway 17- Flow Duration Curve 4.00 - ___ ________ C - Q10 3.00 C 2.00 Q ....... ... 0. 1.00 Existing 0. Qx o.3 IQ. 0.00 0 0.05 0.1 0.15 0.2 0.25 Percentage of time exceeded (%) f I 1 I ' I • I -- ____ -- - -- - - - - - ------------------------ JTT T1 T'T T T 1 ET :r4----------T rT !T Y T r-- C T1'T"T T f T E±7 C•"-r-•-•t•-•--------- rr ..f• ..--.-. !•_•_•_•_•_•l_•_•_•_• -----.-------------------- I ----------- T"1 r 1 "VT" Proposed Flow Duration Curve Data for Raceway Lot 17, Carlsbad CA - POC 1 Q2 = 2.39 cfs Fraction 010 = 3.87 cfs Step = 0.0367 cfs Count = 499679 hours 57.00 years Interval Existing Condition Detention Optimized Pass or Fail? Q (cfs) Hours >0 % time Hours>Q % time Post/Pre 1 0.239 1052 2.11E-01 641 1.28E-01 61% Pass 2 0.275 952 1.91E-01 553 1.11E-01 58% Pass 3 0.312 857 1.72E-01 485 9.71E-02 57% Pass 4 0.349 780 1.56E-01 405 8.11E-02 52% Pass 5 0.385 707 1.41E-01 365 7.30E-02 52% Pass 6 0.422 656 1.31E-01 327 6.54E-02 50% Pass 7 0.459 609 1.22E-01 293 5.86E-02 48% Pass 8 0.496 562 1.12E-01 263 5.26E-02 47% Pass 9 0.532 517 1.03E-01 239 4.78E-02 46% Pass 10 0.569 479 9.59E-02 216 4.32E-02 45% Pass 11 0.606 444 8.89E-02 184 3.68E-02 41% Pass 12 0.642 419 8.39E-02 176 3.52E-02 42% Pass 13 0.679 390 7.81E-02 166 3.32E-02 43% Pass 14 0.716 372 7.44E-02 152 3.04E-02 41% Pass 15 0.753 341 6.82E-02 145 2.90E-02 43% Pass 16 0.789 317 6.34E-02 136 2.72E-02 43% Pass 17 0.826 295 5.90E-02 127 2.54E-02 43% Pass 18 0.863 270 5.40E-02 106 2.12E-02 39% Pass 19 0.899 251 5.02E-02 95 1.90E-02 38% Pass 20 0.936 234 4.68E-02 88 1.76E-02 38% Pass 21 0.973 225 4.50E-02 83 1.66E-02 37% Pass 22 1.009 214 4.28E-02 80 1.60E-02 37% Pass 23 1.046 200 4.00E-02 77 1.54E-02 39% Pass 24 1.083 190 3.80E-02 68 1.36E-02 36% Pass 25 1.120 183 3.66E-02 58 1.16E-02 32% Pass 26 1.156 170 3.40E-02 57 1.14E-02 34% Pass 27 1.193 151 3.02E-02 54 1.08E-02 36% Pass 28 1.230 140 2.80E-02 49 9.81E-03 35% Pass 29 1.266 127 2.54E-02 44 8.81E-03 35% Pass 30 1.303 124 2.48E-02 43 8.61E-03 35% Pass 31 1.340 117 2.34E-02 40 8.01E-03 34% Pass 32 1.377 109 2.18E-02 38 7.60E-03 35% Pass 33 1.413 106 2.12E-02 36 7.20E-03 34% Pass 34 1.450 104 2.08E-02 35 7.00E-03 34% Pass 35 1.487 100 2.00E-02 31 6.20E-03 31% Pass 36 1.523 95 1.90E-02 31 6.20E-03 33% Pass 10% Interval ExistingCondition Detention Optimized Pass or Fail? Q (cfs) Hours > Q % time Hours>Q % time Post/Pre 37 1.560 89 1.78E-02 31 6.20E-03 35% Pass 38 1.597 88 1.76E-02 31 6.20E-03 35% Pass 39 1.634 79 1.58E-02 24 4.80E-03 30% Pass 40 1.670 73 1.46E-02 22 4.40E-03 30% Pass 41 1.707 63 1.26E-02 22 4.40E-03 35% Pass 42 1.744 61 1.22E-02 21 4.20E-03 34% Pass 43 1.780 59 1.18E-02 21 4.20E-03 36% Pass 44 1.817 57 1.14E-02 20 4.00E-03 35% Pass 45 1.854 57 1.14E-02 19 3.80E-03 33% Pass 46 1.890 56 1.12E-02 18 3.60E-03 32% Pass 47 1.927 50 1.00E-02 18 3.60E-03 36% Pass 48 1.964 49 9.81E-03 17 3.40E-03 35% Pass 49 2.001 47 9.41E-03 17 3.40E-03 .36% Pass. 50 2.037 46 9.21E-03 16 3.20E-03 35% Pass 51 2.074 42 8.41E-03 16 3.20E-03 38% Pass 52 2.111 41 8.21E-03 15 3.00E-03 37% Pass 53 2.147 40 8.01E-03 15 3.00E-03 38% Pass 54 2.184 18 7.60E-03 14 2.80E-03 37% Pass 55 2.221 37 7.40E-03 13 2.60E-03 35% Pass 56 2.258 37 7.40E-03 13 2.60E-03 35% Pass 57 2.294 36 7.20E-03 13 2.60E-03 36% Pass 58 2.331 34 6.80E-03 12 2.40E-03 35% Pass 59 2.368 34 6.80E-03 12 2.40E-03 35% Pass 60 2.404 30 6.00E-03 12 2.40E-03 40% Pass 61 2.441 30 6.00E-03 10 2.00E-03 33% Pass 62 2.478 29 5.80E-03 10 2.00E-03 34% Pass 63 2.515 29 5.80E-03 9 1.80E-03 31% Pass 64 2.551 28 5.60E-03 9 1.80E-03 32% Pass 65 2.588 27 5.40E-03 9 1.80E-03 33% Pass 66 2.625 25 5.00E-03 9 1.80E-03 36% Pass 67 2.661 23 4.60E-03 9 1.80E-03 39% Pass 68 2.698 22 4.40E-03 8 1.60E-03 36% Pass 69 2.735 22 4.40E-03 8 1.60E-03 36% Pass 70 2.772 21 4.20E-03 8 1.60E-03 38% Pass 71 2.808 21 4.20E-03 8 1.60E-03 38% Pass 72 2.845 21 4.20E-03 8 1.60E-03 38% Pass 73 2.882 20 4.00E-03 7 1.40E-03 35% Pass 74 2.918 19 3.80E-03 6 1.20E-03 32% Pass 75 2.955 19 3.80E-03 6 1.20E-03 32% Pass 76 2.992 19 3.80E-03 6 1.20E-03 32% Pass 77 3.028 19 3.80E-03 6 1.20E-03 32% Pass 78 3.065 17 3.40E-03 6 1.20E-03 35% Pass 79 3.102 16 3.20E-03 5 1.00E-03 31% Pass 80 3.139 13 2.60E-03 5 1.00E-03 38% Pass 81 3.175 11 2.20E-03 4 8.01E-04 36% Pass Interval ExistingCondition Detention Optimized Pass or Fail? Q (cfs) Hours > Q % time Hours>Q % time Post/Pre 82 3.212 10 2.00E-03 4 8.01E-04 40% Pass 83 3.249 9 1.80E-03 4 8.01E-04 44% Pass 84 3.285 9 1.80E-03 4 8.01E-04 44% Pass 85 3.322 9 1.80E-03 4 8.01E-04 44% Pass 86 3.359 9 1.80E-03 4 8.01E-04 44% Pass 87 3.396 9 1.80E-03 3 6.00E-04 33% Pass 88 3.432 8 1.60E-03 3 6.00E-04 38% Pass 89 3.469 7 1.40E-03 3 6.00E-04 43% Pass 90 3.506 7 1.40E-03 3 6.00E-04 43% Pass 91 3.542 7 1.40E-03 3 6.00E-04 43% Pass 92 3.579 7 1.40E-03 3 6.00E-04 43% Pass 93 3.616 6 1.20E-03 3 6.00E-04 50% Pass 94 3.653 6 1.20E-03 2 4.00E-04 33% Pass 95 3.689 6 1.20E-03 2 4.00E-04 33% Pass 96 3.726 6 1.20E-03 2 4.00E-04 33% Pass 97 3.763 6 1.20E-03 2 4.00E-04 33% Pass 98 3.799 6 1.20E-03 2 4.00E-04 3351. Pass 99 3.836 6 1.20E-03 2 4.00E-04 33% Pass 100 3.873 6 1.20E-03 2 4.00E-04 33% Pass Peak Flows calculated with Cunnane Plotting Position Return Period Pre-dev. ci Post-Dev. Q Reduction 10 3.873 2.793 1.080 9 3.676 2.782 0.894 8 3.516 2.682 0.834 7 3.420 2.471 0.949 6 3.226 2.348 0.878 5 3.126 2.157 0.969 4 3.079 1.909 1.170 3 2.717 1.601 1.116 2 2.386 1.436 0.950 ATTACHMENT 3 List of the "n" Largest Peaks: Pre & Post-Developed Conditions List of Peak events and Determination of P2 and PlO (Post-Development) Raceway 17 - POC 1 T Cunnane Welbull Peaks Date Posit Period of Return 10 2.79 2.83 Weibull Cunnane 9 2.78 2.79 1.005 1/9/1980 57 1.02 1.01 8 2.68 2.73 1.009 1/25/1969 56 1.04 1.03 7 2.47 2.54 1.019 12/24/1971 55 1.05 1.05 6 2.35 2.36 1.021 11/18/1986 54 1.07 1.07 5 2.16 2.19 1.026 12/28/2004 53 1.09 1.09 4 1.91 1.92 1.041 2/22/2005 52 1.12 1.11 3 1.60 1.60 1.05 12/25/1983 51 1.14 1.13 2 1.44 1.44 1.057 1/11/1980 50 1.16 1.15 Note: Cunnane is the preferred method by the HMP permit. 1.057 12/24/1988 49 1.18 1.18 1.059 2/18/1980 48 1.21 1.20 1.061 2/13/1992 47 1.23 1.23 1.062 11/30/2007 46 1.26 1.25 1.114 2/12/2003 45 1.29 1.28 1.126 1/14/1993 44 1.32 1.31 1.144 2/6/1969 43 1.35 1.34 1.151 2/18/2005 42 1.38 1.38 1.161 3/5/1995 41 1.41 1.41 1.175 1/20/1962 40 1.45 1.44 1.183 3/3/1983 39 1.49 1.48 1.193 4/27/1960 38 1.53 1.52 1.224 1/11/2005 37 1.57 1.56 1.256 11/22/1996 36 1.61 1.61 1.27 8/17/1977 35 1.66 1.65 1.302 9/23/1986 34 1.71 1.70 1.307 1/16/1972 33 1.76 1.75 1.307 3/2/1980 32 1.81 1.81 1.326 2/17/1998 31 1.87 1.87 1.434 1/16/1978 30 1.93 1.93 1.436 1/9/2005 29 2.00 2.00 1.447 1/16/1993 28 2.07 2.07 1.562 2/10/1978 27 2.15 2.15 1.567 2/3/1998 26 2.23 2.23 1.568 12/30/1991 25 2.32 2.33 1.578 3/8/1968 24 2.42 2.42 1.58 1/15/1978 23 2.52 2.53 1.582 1/13/1997 22 2.64 2.65 1.583 2/23/2005 21 2.76 2.78 1.6 1/6/1979 20 2.90 2.92 1.602 2/23/1998 19 3.05 3.08 1.766 2/22/2008 18 3.22 3.25 1.78 2/15/1986 17 3.41 3.45 1.804 1/16/1952 16 3.63 3.67 1.892 3/1/1991 15 3.87 3.92 1.952 10/27/2004 14 4.14 4.21 2.012 2/4/1958 13 4.46 4.54 2.136 2/25/2003 12 4.83 4.93 2.28 1/29/1980 11 5.27 5.40 2.346 11/22/1965 10 5.80 5.96 2.377 3/17/1982 9 6.44 6.65 2.613 2/20/1980 8 7.25 7.53 2.778 3/1/1978 7 8.29 8.67 2.795 10/1/1983 6 9.67 10.21 3.01 2/25/1969 5 11.60 12.43 3.08 1/4/1978 4 14.50 15.89 3.548 1/15/1979 3 19.33 22.00 4.421 1/4/1995 2 29.00 35.75 5.022 4/14/2003 1 58.00 95.33 List of Peak events and Determination of P2 and PlO (Pre-Development) Raceway 17 - POC 1 T Cunnane Weibull Peaks Date Posit Period of Return 10 3.87 3.99 Weibull Cunnane 9 3.68 3.77 1.701 1/11/1980 57 1.02 1.01 8 3.52 3.57 1.707 2/23/2005 56 1.04 1.03 7 3.42 3.43 1.732 4/28/2005 55 1.05 1.05 6 3.23 3.27 1.754 1/11/2005 54 1.07 1.07 5 3.13 3.13 1.807 3/1/1991 53 1.09 1.09 4 3.08 3.09 1.817 2/22/1998 52 1.12 1.11 3 2.72 2.73 1.866 8/17/1977 51 1.14 1.13 2 2.39 2.39 1.892 12/25/1968 50 1.16 1.15 Note: Cunnane is the preferred method by the HMP permit. 1.895 2/8/1993 49 1.18 1.18 1.916 3/19/1981 48 1.21 1.20 1.916 2/12/1992 47 1.23 1.23 1.919 12/22/1982 46 1.26 1.25 1.925 4/27/1960 45 1.29. 1.28 1.932 2/14/1998 44 1.32 1.31 1.977. 3/15/1986 43 1.35 1.34 1.991 .3/11/1995 42 1.38 1.38 2.034 1/16/1972 . 41 1.41 1:41 2.071 2/15/1986 40 1.45 1.44 2.073 1/18/1993 39 1.49 1.48 2.083 12/2/1961 38 1.53 1.52 2.138 3/17/1963 37 1.57 1.56 2.154 1/29/1980 36 1.61 1.61 2.159 2/4/1994 35 1.66 1.65 2.213 1/16/1978 34 1.71 1.70 2.288 10/20/2004 33 1.76 1.75 2.317 2/17/1998 32 1.81 1.81 2.328 2/18/1993 31 1.87 1.87 2.373 11/15/1952 30 1.93 1.93 2.386 2/27/1983 29 2.00 2.00 2.392 2/16/1980 28 2.07 2.07 2.404 11/11/1985 27 2.15 2.15 2.477 2/23/1998 26 2.23 2.23 2.546 12/30/1991 25 2.32 2.33 2.562 1/29/1983 24 2.42 2.42 2.6 11/22/1965 23 _2.52 2.53 2.632 2/3/1998 22 2.64 2.65 2.64 12/19/1970 21 2.76 2.78 2.673 2/10/1978 20 2.90 2.92 2.758 3/2/1980 19 3.05 3.08 2.856 4/1/1958 18 3.22 3.25 3.031 3/17/1982 17 3.41 3.45 3.046 3/1/1978 16 3.63 3.67 3.066 1/16/1952 15 . 3.87 3.92 3.112 1/14/1993 14 4.14 4.21 3.112 10/29/2000 13 4.46 4.54 3.121 2/20/1980 12 4.83 4.93 3.156 2/18/2005 11 5.27 5.40 3.215 10/27/2004 10 5.80 5.96 3.401 2/25/1969 9 6.44 6.65 3.449 2/4/1958 . 8 7.25 7.53 3.61 2/25/2003 7 8.29 8.67 3.915 9/23/1986 6 9.67 10.21 4.342 1/4/1995 5 11.60 12.43 4.509 1/15/1979 4 14.50 15.89 4.797 10/1/1983 3 19.33 22.00 4.913 1/4/1978 2 29.00 35.75 5.326 4/14/2003 1 58.00 95.33 ATTACHMENT 4 AREA VS ELEVATION The LID module allows for the direct input of surface storage depth and BMP footprint area to determine surface ponded volume. As such no stage-storage calculations are required for this analysis. DISCHARGE VS ELEVATION The orifice has been selected to maximize their size while still restricting flows to conform with the required 10% of the Q2 event flow as mandated in the Final Hydromodification Management Plan by Brown & Caldwell, dated March 2011.. While TRWE acknowledges that these orifices are small, to increase the size of these outlets would impact the basin's ability to restrict flows beneath .the HMP thresholds, thus preventing the BMP from conformance with HMP requirements. In order to further reduce the risk of blockage of the orifices, regular maintenance of the riser and orifices must be performed to ensure potential blockages are minimized. A detail of the orifice and riser structure is provided in Attachment 5 of this memorandum. No stage-storage calculations were performed for the ultimate condition as there are no surface orifices; all flows drain via the low flow orifice beneath the HMP facility or via the emergency spillway to the receiving storm drain system. ATTACHMENT 5 Pre & Post-Developed Maps, Project Plan and Detention Section Sketches RISER OUTLET STRUCTURE 24" AMENDED SOIL , 1/N. INFIL iRA liON 7 RA TE 5 '/HR. 2 'I GRAVEL LA H BASIN TOP ELEV BASIN INVERT SO TTOM OF AMENDED SOIL LID INVERT-SO TTOM OF GRA VEL LID ORIFICE EXIST GROUND A BIORETEN liON AREA B/ORE TEN TION AREA CROSS SECT/ON 'TYP) NOT TO SCALE BMP H(FT) Hmax (Fl) Hg (Fl) LID (INCHES) Ag (FTA2) Abot (FTA2) 1 0.83 1.32 0.5 1.25 2016 2016 2 0.83 1.4 0.5 1.5 4489 4489' 3 0.83 1.4 0.5 1.75 3462 3003 ,,,rrr, lilA LID ORIFICE DETAIL NOT TO SCALE FRENCH GRA VEL S TORA ?R PL iF ATTACHMENT 6 SWMM Input Data in Input Format (Existing & Proposed Models) POST_DEV (TITLE) [OPTIONS] FLOW—UNITS CFS INFILTRATION GREEN_AMPT FLOW—ROUTING KINWAVE START DATE 10/01/1951 START_TIME 00:00:00 REPORT—START—DATE 10/01/1951 REPORT—START—TIME 00:00:00 END—DATE 09/30/2008 END—TIME 23:00:00 SWEEP—START 01/01 SWEEP_END 12/31 DRY—DAYS 0 REPORT—STEP 01:00:00 WET—STEP 00:15:00 DRY—STEP 04:00:00 ROUTING_STEP 0:01:00 ALLOW_PONDING NO INERTIAL—DAMPING PARTIAL VARIABLE—STEP 0.75 LENGTHENING_STEP 0 MIN_SURFAREA 0 NORMAL—FLOW—LIMITED BOTH SKIP—STEADY—STATE NO FORCE—MAIN—EQUATION H-W LINK—OFFSETS DEPTH MIN—SLOPE 0 (EVAPORATION] ;;Type Parameters MONTHLY .041 .076 .118 DRY ONLY NO (RAINGAGES] .192 .237 .318 .308 .286 .217 .14 .067 .041 Rain Time Snow Data ;;Name Type Intrvl Catch Source Oceanside INTENSITY 1:00 1.0 TIMESERIES Oceanside (SUBCATCHMENTS] Total Pcnt. Pcnt. Curb Snow ;;Name Raingage Outlet Area Impery Width Slope Length Pack ;Subarea A w/o bioretention DMA-1 Oceanside BR-1 0.564 70.96 71 1 0 BR-1 Oceanside POC-1 0.046281 0 10 0 0 DMA-2 Oceanside BR-2 1.347 90.58 128 1 0 BR-2 Oceanside POC-1 0.103053 0 10 . 0 0 DMA-3 Oceanside BR-3 2.323 81.32 172 1 0 BR-3 Oceanside POC-i 0.079477 0 10 0 0 DMA-4 Oceanside BR-4 0.11 81.82 42 1 0 BR-4 Oceanside POC-1 0.000391 0 10 '0 0 DMA-BYPASS Oceanside POC-i 0.13774 100 50 1 0 (SUBAREAS] ;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted DMA-i .012 0.05 .02 .1 25 OUTLET BR-1 0.012 0.1 .02 .1 25 OUTLET POST_DEV DMA-2 .012 0.05 .02 .1 25 OUTLET BR-2 .012 0.05 .02 .1 25 OUTLET DMA-3 .012 0.05 .02 .1 25 OUTLET BR-3 0.012 0.1 .02 .1 25 OUTLET DMA-4 .012 0.05 .02 .1 25 OUTLET BR-4 0.012 0.1 .02 .1 25 OUTLET DMA-BYPASS .012 0.05 .02 .1 25 OUTLE1 (INFILTRATION) ;;Subcatchment Suction HydCon IMDmax DMA-i 9 0.01875 0.3 BR-1 9 0.01875 0.3 DMA-2 9 0.01875 0.3 BR-2 9 0.01875 0.3 DMA-3 9 0.01875 0.3 BR-3 9 0.01875 0.3 DMA-4 9 0.01875 0.3 BR-4 9 0.01875 0.3 DMA-BYPASS 9 0.01875 0.3 [LID-CONTROLS] Type/Layer Parameters LID-i BC LID-1 SURFACE 11.158 0.05 0 0 5 LID-1 SOIL 24 0.4 0.2 0.1 5 5 1.5 LID-1 STORAGE 6 0.67 0 0 LID-1 DRAIN 0.2581 0.5 0 6 LID-2 BC LID-2 SURFACE 10.915 0.05 0.0 0.0 5 LID-2 SOIL 24 0.4 0.2 0.1 5 5 1.5 LID-2 STORAGE 6 0.67 0 0 LID-2 DRAIN 0.1669 0.5 0 6 LID-3 BC LID-3 SURFACE 9.3 0.05 0.0 0.0 5 LID-3 SOIL 24 0.4 0.2 0.1 5 5 1.5 LID-3 STORAGE 6 0.67 0 0 LID-3 DRAIN 0.2945 0.5 0 6 LID-4 BC LID-4 SURFACE 6 0.0 0.0 0.0 5 LID-4 SOIL 24 0.4 0.2 0.1 100 5 1.5 LID-4 STORAGE 6 0.67 0 0 LID-4 DRAIN 11.0171 0.5 0 6 (LID-USAGE] ;;Subcatchment LID Process Number Area Width InitSatur Fromlmpry ToPery Report File BR-i LID-1 1 2016 0 0 100 0 "BR-A.txt' BR-2 LID-2 1 4489 0 0 100 0 BR-3 LID-3 1 3462 0 0 100 0 BR-4 LID-4 1 17 0 0 100 0 OUT FALLS] Invert Outfall Stage/Table Tide ;;Name Elev. Type Time Series Gate POC-1 0 FREE NO POST_DEV (TIMESERIES) Name Date Time Value Oceanside FILE "OsideRain . prn (REPORT) INPUT NO CONTROLS NO SUBCATCHMENTS ALL NODES ALL LINKS ALL (TAGS] (MAP) DIMENSIONS 0.000 0.000 10000.000 10000.000 Units None (COORDINATES) S. ;;Node X-Coord Y-Coord POC-1 0.000 3300.000 (VERTICES) ;;Link X-Coord Y-Coord (Polygons) ;;Subcatchment X-Coord Y-Coord DMA-i -1500.000 9200.000 BR-1 -1500.000 7200.000 DMA-2 -500.000 9200.000 BR-2 -500.000 7200.000 DMA-3 500.000 9200.000 BR-3 500.000 7200.000 DMA-4 1500.000 9200.000 BR-4 1500.000 7200.000 DMA-BYPASS 2000.000 3300.000 [SYMBOLS] ;;Gage X-Coord Y-Coord Oceanside 6079.665 8029.350 f PRE_DEV (TITLE) (OPTIONS] FLOW UNITS CFS INFILTRATION GREEN_AMPT FLOW ROUTING KINWAVE START DATE 10/17/1948 START TIME 00:00:00 REPORT—START—DATE 10/17/1948 REPORT_START_TIME 00:00:00 END—DATE 10/17/2005 END—TIME 23:00:00 SWEEP_START 01/01 SWEEP_END 12/31 DRY—DAYS 0 REPORT_STEP 01:00:00 WET—STEP 00:15:00 DRY STEP 04:00:00 ROUTING_STEP 0:01:00 ALLOW_PONDING NO INERTIAL—DAMPING PARTIAL VARIABLE—STEP 0.75 LENGTHENING—STEP 0 MIN_SURFAREA 0 NORMAL—FLOW—LIMITED BOTH SKIP—STEADY—STATE NO FORCE—MAIN—EQUATION H-W LINK—OFFSETS DEPTH MIN—SLOPE 0 (EVAPORATION] ;;Type Parameters MONTHLY 0.041 0.076 0.118 0.192 0.237 0.318 0.308 0.286 0.217 0.14 0.067 0.041 DRY—ONLY NO [RAINGAGES) Rain Time Snow Data ;;Name Type Intrvl Catch Source OCEANSIDE INTENSITY 1:00 1.0 TIMESERIES OCEANSIDE I S UBCATCHMENTS I Total Pcnt. Pcnt. Curb Snow ;;Name Raingage Outlet Area Impery Width Slope Length Pack DMA-1 OCEANSIDE POC-1 4.71 0 376 2.7 0 (SUBAREAS) ;;Subcatchment N-Impery N-Pery S-Impery S-Pery PctZero RouteTo PctRouted DMA-1 0.012 0.05 0.02 0.1 25 OUTLET [INFILTRATION] ;;Subcatchment Suction HydCon IMDmax DMA-1 9 0.01875 0.3 (OUTFALLS) Invert Outfall Stage/Table Tide ;;Name Elev. Type Time Series Gate PR E_DE V PCC-i 0 FREE NO (TIMESERIES) ;;Name Date Time Value OCEANSIDE FILE "OsideRain.prn" [REPORT) INPUT NO CONTROLS NO SUBCATCHMENTS ALL NODES ALL LINKS ALL (TAGS] (MAP) DIMENSIONS 0.000 0.000 10000.000 10000.000 Units None (COORDINATES) ;;Node X-Coord Y-Coord POC-i 2500.000 2700.000 (VERTICES) ;;Link X-Coord Y-Coord (Polygons) ;;Subcatchment X-Coord Y-Coord DMA-i 2500.000 6000.000 DMA-1 2500.000 6000.000 (SYMBOLS) ;;Gage X-Coord Y-Coord OCEANSIDE 1525.424 6864.407 ATTACHMENT 7 EPA SWMM FIGURES AND EXPLANATIONS Per the attached, the reader can see the screens associated with the EPA-SWMM Model in both pre-development and post-development conditions. Each portion, i.e., sub-catchments, outfalls, storage units, weir as a discharge, and outfalls (point of compliance), are also shown. Variables for modeling are associated with typical recommended values by the EPA-SWMM model; typical values found in technical literature (such as Maidment's Handbook of Hydrology).. Recommended values for the SWMM model have been attained from the interim Orange County criteria established for their SWMM calibration. Currently, no recommended values have been established by the San Diego County HMP Permit for the SWMM Model. Soil characteristics .of the existing soils were determined from the site specific geotechnical report. Some values incorporated within the SWMM model have been determined from the professional experience of TRWE using conservative assumptions that have a tendency to increase the size of the needed BMP and also generate a long-term runoff as a percentage of rainfall similar to those measured in gage stations in Southern California by the USGS. EXPLANATION OF SELECTED VARIABLES Sub Catchment Areas: Please refer to the attached diagrams that indicate the DMA and Bio-Retention BMPs (BMP) sub areas modeled within the project site at both the pre and post developed conditions draining to the POC. Parameters for the pre- and post-developed models include soil type 0 as determined from the County of San Diego Hydrology Manual Soils Maps (attached at the end of this appendix). Suction head, conductivity and initial deficit corresponds to average values expected for these soils types, according to sources consulted, professional experience, and approximate values obtained by the interim Orange County modeling approach. TRWE selected infiltration values, such that the percentage of total precipitation that becomes runoff, is realistic for the soil types and slightly smaller than measured values for Southern California watersheds. Selection of a Kinematic Approach: As the continuous model is based on hourly rainfall, and the time of concentration for the pre-development and post-development conditions is significantly smaller than 60 minutes, precise routing of the flows through the impervious surfaces, the underdrain pipe system, and the discharge pipe was considered unnecessary. The truncation error of the precipitation into hourly steps is much more significant than the precise routing in a system where the time of concentration is much smaller than 1 hour. Sub-catchment BMP: The area of bio-retention must be equal to the area of the development tributary to the bioretention facility (area that drains into the bioretention, equal external area plus bio-retention itself). Five (5) decimal places were given regarding the areas of the bio-retention to insure that the area used by the program for the LID subroutine corresponds exactly with this tributary. LID Control Editor: Explanation of Significant Variables Storage Depth: The storage depth variable within the SWMM model is representative of the storage volume provided beneath the engineered soil and mulch components of the bioretention facility. Porosity: A porosity value of 0.4 has been selected for the model. The amended soil is to be highly sandy in content in order to have a saturated hydraulic conductivity of approximately 5 in/hr. The Contech proprietary unit (LID 4) was modeled using the designated 100 in/hr rate. TRWE considers such a value (5 in/hr) to be slightly high; however, in order to comply with the HMP Permit, the value recommended by the Copermittees for the porosity of amended soil is 0.4, per Appendix A of the Final Hydromodification Management Plan by Brown & Caldwell, dated March 2011. Such porosity is equal to the porosity of the gravel per the same document. Void Ratio: The ratio of the void volume divided by the soil volume is directly related to porosity as n/(1-n). As the u'nderdrain layer is composed of gravel, a porosity value of 0.4 has been selected (also per Appendix A of the Final HMP document), which results in a void ratio of 0.4/(1-0.4) = 0.67 for the gravel detention layer. Conductivity: Due to the natural soil existing on site, infiltration was a viable addition to the LID design. As the BMP is to be lined, the conductivity value was set to 0 to represent zero infiltration. Clogging factor: A clogging factor was not used (0 indicates that there is not clogging assumed within the model). The reason for this is related to the fairness of a comparison with the SDHM model and the HMP sizing tables: a clogging factor was not considered, and instead, a conservative value of infiltration was recommended. Drain (Flow) coefficient: The flow coefficient in the SWMM Model is the coefficient needed to transform the orifice equation into a general power law equation of the form: q=C(HH)'1 (1) where q is the peak flow in in/hr, n is the exponent (typically 0.5 for orifice equation), HD is the elevation of the centroid of the orifice in inches (assumed equal to the invert of the orifice for small orifices and in our design equal to 0) and H is the depth of the water in inches. The general orifice equation can be expressed as: ir D2 (H-HD) Q=c9 — I2g (2) 144 12 where Q is the peak flow in cfs, 0 is the diameter in inches, cg is the typical discharge coefficient for orifices (0.61-0.63 for thin walls and around 0.75-0.8 for thick walls), g is-the acceleration of gravity in ft/s2, and H and HD are defined above and are also used in inches in Equation (2). ATTACHMENT 8 Soils Map County of San Diego Hydrology Manual Soil Hydrologic Groups Soil Groups Group Group B Group C Group D Undetermined Data Unavailable 2 I E o 33 33 30 I - Cor L 0 L — T (I I / -- 3315 T go ji ~ ; Iriy Lit 3315 OCEANsIDE I J 0_f •0• - N 0 , CARLSBAD \ ' ,. .- 2 ENCINI 3300____TI : T ]L S .D. COIJI)TY Pow/ Y Q DEL MA 70 I I ) lNTFE) Ny '1 0 I 14-A 'DIF ky I I L CAJ f — J 32045 :. MIA -----'--- -------- --i------ - - -- •---- 2045 ORION, \ 7' C LK S IA - 0 0 •0 'N., i - IMPERIAL BEACH - 32°30 32°30 1 ro. I - o_ 0 0 (C DPW GJS SanGIS Wi Hav San ftk- N THIS MAP IS PROVIDED WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS * OR IMPLIED, INCLUDING. BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Copyright SanDlS. All Rights Reserved. This products may contain information from the SANDAG Regional E Information System which cannot be reproduced without the written perrnissiorn of SANDAG. This Product may contain information which has been reproduced with permission granted by Thomas Brothers Maps. S 3 0 3MiIes ATTACHMENT 9 Summary Files from the SWMM Model POST_DEV EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.022) -------------------------------------------------------------- ********************************************************* NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. * ** * * * * * Analysis Options Flow Units ...............CFS Process Models: Rainfall/Runoff ........YES Snowmelt ................NO Groundwater............NO Flow Routing ...........NO Water Quality ..........NO Infiltration Method ......GREEN AMPT Starting Date ............00T-01-1951 00:00:00 Ending Date ..............SEP-30-2008 23:00:00 Antecedent Dry Days ......0.0 Report Time Step .........01:00:00 Wet Time Step ............00:15:00 Dry Time Step .............04:00:00 * * * ****** ********* * **** * ** Volume Depth Runoff Quantity Continuity acre-feet inches * * * * * * * * * * * * * * * * * * * * * * * * * Total Precipitation 264.739 674.360 Evaporation Loss 44.408 113.120 Infiltration Loss 29.585 75.361 Surface Runoff ...........193.557 493.040 Final Surface Storage 0.009 0.022 Continuity Error (%) -1.065 Volume Volume Flow Routing Continuity acre-feet --------- 106 gal --------- Dry Weather Inflow 0.000 0.000 Wet Weather Inflow 193.557 63.073 Groundwater Inflow 0.000 0.000 DII Inflow ..............0.000 0.000 External Inflow 0.000 0.000 External Outflow 193.557 63.073 Internal Outflow 0.000 0.000 Storage Losses 0.000 0.000 Initial Stored Volume 0.000 0.000 Final Stored Volume 0.000 0.000 Continuity Error (%) 0.000 ** * * * * * * * * *** **** ***** * * Subcatchment Runoff Summary POST_DEV Total Total Total Total Total Total Peak Runoff Precip Runon Evap Infil Runoff Runoff Runoff Coeff Subcatchment in in in in in 106 gal CFS DMA-1 674.36 0.00 -------------------------------------------------------------------------------------------------------- 60.93 138.59 481.55 7.37 0.67 0.714 BR-1 674.36 5868.35 894.80 0.00 5671.61 7.13 0.70 0.867 DMA-2 674.36 0.00 74.87 44.63 560.75 20.51 1.61 0.832 BR-2 674.36 7329.56 925.41 0.00 7096.07 19.86 1.73 0.887 DMA-3 674.36 0.00 70.46 89.24 519.92 32.80 2.76 0.771 BR-3 674.36 15196.49 1003.88 0.00 14919.25 32;20 2.85 0.940 DMA-4 674.36 0.00 62.90 85.79 535.61 1.60 0.13 0.794 BR-4 674.36 150684.44 1157.88 21.72 151023.98 1.60 0.13 0.998 DMA-BYPASS 674.36 0.00 73.09 0.00 610.82 2.28 0.17 0.906 LID Performance Summary Total Evap ------------------------------------------------------------------------------------------------------------------ Infil Surface Drain Init. Final Pcnt. Inflow Loss Loss Outflow Outflow Storage Storage Error Subcatchment LID Control in in in in in in in BR-i LID-1 6542.71 894.84 ------------------------------------------------------------------------------------------------------------------ 0.00 113.15 5558.67 0.00 0.00 -0.37 BR-2 LID-2 8003.92 925.44 0.00 385.72 6710.59 0.00 0.00 -0.22 BR-3 LID-3 15870.85 1003.92 0.00 3054.32 11865.56 0.00 0.00 -0.33 BR-4 LID-4 151358.80 1153.30 0.00 97198.58 54114.86 0.00 0.00 -0.73 Analysis begun on: Thu Sep 05 09:03:32 2013 Analysis ended on: Thu Sep 05 09:03:53 2013 Total elapsed time: 00:00:21 PRE_DEV EPA STORM WATER MANAGEMENT MODEL - VERSION 5.0 (Build 5.0.022) ****************************** *************************** NOTE: The summary statistics displayed in this report are based on results found at every computational time step, not just on results from each reporting time step. ********************************************************* Analysis Options Flow Units ...............CFS Process Models: Rainfall/Runoff ........YES Snowmelt ................NO Groundwater ............NO Flow Routing ...........NO Water Quality ..........NO Infiltration Method ......GREEN AMPT Starting Date ............00T-17-1948 00:00:00 Ending Date ..............00T-17-2005 23:00:00 Antecedent Dry Days ......0.0 Report Time Step .........01:00:00 Wet Time Step ............00:15:00 Dry Time Step ............04:00:00 Volume Depth Runoff Quantity Continuity acre-feet inches Total Precipitation 255.239 650.290 Evaporation Loss 11.602 29.558 Infiltration Loss 184.919 471.131 Surface Runoff 64.297 163.813 Final Surface Storage 0.000 0.000 Continuity Error (%) -2.186 Volume Volume Flow Routing Continuity acre-feet 106 gal Dry Weather Inflow 0.000 0.000 Wet Weather Inflow 64.297 20.952 Groundwater Inflow 0.000 0.000 RDII Inflow ..............0.000 0.000 External Inflow 0.000 0.000 External Outflow 64.297 20.952 Internal Outflow 0.000 0.000 Storage Losses 0.000 0.000 Initial Stored Volume 0.000 0.000 Final Stored Volume 0.000 0.000 Continuity Error (%) 0.000 ** * * * * **** ******** * Subcatchment Runoff Summary *** * * * * * * *** ** **** *** PRE DEV Subcatchment ----------------- DMA-i Total Total Precip Runon in in ----------------- 650.29 0.00 Total Total Total Total Peak Runoff Evap Infil Runoff Runoff Runoff Coeff in in in 106 gal CFS 29.56 471.13 -------------------------------------------------------- 163.81 20.95 5.33 0.252 Analysis begun on: Wed Sep 04 11:33:54 2013 Analysis ended on: Wed Sep 04 11:34:09 2013 Total elapsed time: 00:00:15 ATTACHMENT 4 URBAN GREEN® BIOFILTRATION SPECIFICATIONS AND DETAILS C*NTECH' ENGINEERED SOLUTIONS PERFORMANCE OVERVIEW Performance of the UrbanGreen BioFilter with 2P Biomedia for the Removal of Suspended Solids, Total Phosphorus and Heavy Metals from Stormwater Runoff Introduction The effectiveness of biofiltration systems as a means of treating urban runoff is well documented. A growing body of biofilter performance data demonstrates that flow through biofiltration systems consistently remove high levels of many common stormwater pollutants. A biofilter monitored for several years at the University of New Hampshire Stormwater Center achieved 87% Total Suspended Solids(TSS) removal, 99% Total Petroleum Hydrocarbons-Diesel Range(TPH-D) removal, 68% Total Zinc removal, 34% Total Phosphorous(TP) removal and has reduced average annual peak flows by 79% (UNH, 2009). A University of Virginia biofilter study reported equally impressive removal efficiencies, 86% ISS, 90% TP, 97% COD and 67% Oil and Grease (Vu et al, 1999). Biofiltration combines physical filtration and reactive processes with biological processes to maximize the removal of stormwater pollutants. Biofiltration systems are typically composed of a soil media that includes an organic component such as compost, peat or mulch as well as native vegetation, all of which aid in pollutant removal. Water is introduced to the surface of the system where it ponds and then filters through the soil media. The soil media filters particulate pollutants both at the surface as well as within the media bed. The addition of an organic component such as compost or peat to the media allows the system to sequester dissolved pollutants through reactive processes such as cation exchange. The inclusion of vegetation also adds a number of benefits to the system including nutrient uptake, increased evapotranspiration, promotion of beneficial bacterial growth, improved aesthetics and increased hydraulic conductivity. While much of the pollutant load is removed via filtration, employment of multiple unit processes within the system enhances performance in comparison with basic media filters (Clar et al, 2004). UrbanGreen BioFilter The UrbanGreen"A BioFilter is a high capacity tree well style biofilter housed within a concrete vault. The biofilter is modeled after conventional biofilter designs with a few notable enhancements to maximize performance, hydraulic conductivity and longevity. The engineered biomedia is comprised of an optimized blend of sand and peat granules. The consistent, engineered media blend ensures that each unit performs as intended, and eliminates the complications and uncertainty caused by trying to blend a biofiltration media to specification onsite. The UrbanGreen BioFilter utilizes an internal bypass to convey extreme flows, so when desirable the system may be placed online without the need for an external bypass structure. The UrbanGreen BioFilter has a design saturated hydraulic conductivity (infiltration rate) of 100 in/hr and a media bed depth of 24 inches. An outlet flow control limits the infiltration rate so significant pollutant loads can accumulate before the media drops below the design infiltration rate and maintenance is required. Unregulated, 2P biomedia has been shown to have a saturated hydraulic conductivity exceeding 300 in/hr. Using an outlet flow control rather than the media to control infiltration rates allows soil with a higher void volume to be used and makes system performance much more consistent over time. This substantially decreases the frequency of maintenance because there is more storage volume for captured pollutants within the biomedia. Performance is also improved by reducing velocities in the pore spaces within the biomedia (Contech 2011). PERFORMANCE OVERVIEW concentrations well below the intended target. More importantly, the system still achieved positive removal of dissolved lead despite the low influent concentrations. All results have been summarized and included in Table 2 below. Pollutant Percent Removal Diss. Zn 95 Diss. Cu 84 Diss. Pb 36 Table 2. Results of UrbanGreen Biofilter Dissolved Metals Removal Laboratory Trials with a 24 Inch bed of 2P Blomedla at a Hydraulic Rate of 100m/hr. Overall, the UrbanGreen BioFilter showed excellent removal of dissolved metals across varying influent concentrations. Retention of dissolved metals in addition to the capture of particulate bound metals will result in a reduction of the total metals load transported by stormwater runoff that exceeds the capability of systems only targeting particulate metals. Conclusions Multiple studies have demonstrated that a 24 inch deep bed of 2P biomedia operated at a controlled saturated hydraulic conductivity (infiltration rate) of 100 in/hr is highly effective at removing suspended solids, total phosphorus and dissolved metals from stormwater runoff. Over the course of seven trials at a design infiltration rate of 100 in/hr with influent concentrations ranging from 0-300 mg/L the 2P biomedia removed 93% of Sil-Co-Sil® 106. During a second set of seven trials conducted at a design infiltration rate of 200 in/hr with influent concentrations ranging from 2-310 mg/L the 2P biomedia removed 89% of Sil-Co-Sil® 106. A trial spanning 30 hours of system operation revealed that the 2P biomedia removed on average 99% of stormwater solids and reduced effluent solids concentrations to 2mg/L on average. During the same study the 2P biomedia retained on average 83% of the total phosphorus load. The average effluent TP concentration during the 30 hours of sampling was 0.021mg/L. Three laboratory trials spanning two days each showed that a 24 inch deep bed of 2P biomedia operated at a controlled infiltration rate of lOGin/hr was able to remove 95% of dissolved zinc based on linear regression. Three additional laboratory trials demonstrated that a 24 inch deep bed of 2P biomedia operated at a controlled infiltration rate of 100m/hr was able to remove 84% of dissolved copper based on linear regression. Three laboratory trials spanning two days each showed that a 24 inch deep bed of 2P biomedia operated at a controlled infiltration rate of lOGin/hr was able to reduce dissolved lead concentrations by 36% on average. Hydraulic testing confirmed that the engineered 2P biomedia blend has an initial hydraulic conductivity exceeding 300 in/hr. Performance trials demonstrated the ability of 2P biomedia to remove 89% of Sil- Co-Sil 106 at a design infiltration rate of 200 in/hr, making 2P media an optimal choice for high rate biofiltration applications. Collectively, these results demonstrate that the UrbanGreen Biofilter with 2P media represents a highly effective means of treating urban runoff. 02012 Contech Engineered Solutions, LLC Page 6 of 7 www.ContechES.com PERFORMANCE OVERVIEW References Clar, M.L., Barfield, B. J., and O'Connor, T. P. (2004). Stormwater Best Management Practice Design Guide Volume 2 Vegetated Biofilters. Cincinatti, OH, USEPA. Available Online: http://www.epa.izov/nrmrl/pubs/6OOrO4l2l/6OOrO4l2la.pdf CONTECH Engineered Solutions. (2011). Managing Urban Runoff with the UrbanGreen BioFilter. Scarborough, ME. Author. Ma, J. and Tracy, K. (2012a). Removal of Sil-Co-Sil 106 by 2P Biomedia (050 = 4 mm) 100 in/hr and 24 inch Media Column Testing. Portland, OR. Author. Ma, J. and Tracy, K (2012b). TP Removal Using UG 2P Biomedia. Portland, OR. Author Ma, J; And Tracy, K. (2012c). Removal of Dissolved Metals and Nutrients by 2P Biomedia. Portland, OR. Author. Lenth, J., Dugopolski, R., Quigley, M., Poresky, A., and Leisenring, M. (2010). Filterra Bioretention Systems: Technical Basis for High Flow Rate Treatment and Evaluation of Stormwater Quality Performance. Seattle, WA. Author. University of New Hampshire Stormwater Center. (2009). 2009 Biannual Report. Durham, NH: Author. Available Online: http://www.unh.edu/unhsc/sites/unh.edu.unhsc/files/pubs specs info/2009 unhsc report.pdf Vu, S.L., X. Zhang, A.Earles, and M. Sievers, (1999). "Field Testing of Ultra-urban BMPs". Proceedings of the 26th Annual Water Resources Planning and Management Conference, E. Wilson (Ed.), ASCE, June 6- 9, 1999, Tempe AZ. 02012 Contech Engineered Solutions, LLC Page 7 of 7 www.ContechES.com CONTECH® ENGINEERED SOLUTIONS U R B A N R I E NTM p BioFilter Maintenance Manual :V It 4 'S dr 4. TVI -'-. rh Ail t'• BioFilter UrbanGreen BioFilter Inspection and Maintenance The UrbanGreen BioFilter should be inspected at regular intervals and maintained when necessary to ensure optimum performance. The rate at which the system collects pollutants will depend more heavily on site activities than the size of the unit (i.e. unstable soils or heavy winter sanding will cause the system to fill more quickly but regular sweeping will slow accumulation). Maintenance of the UrbanGreen BioFilter should be performed by a qualified professional who has experience with maintenance of stormwater management systems. For more information, please contact CONTECH at 800.338.1122 or info@contech-cpi.com. Inspection and Routine Maintenance Inspection is the key to effective maintenance. Inspect annually unless local regulations or site conditions require more frequent inspection: Routine maintenance, defined as trash and debris removal and general upkeep, should be performed during each inspection if necessary. First record the height, width and condition of the tree. A sample log is provided. Once these recordings have been taken, the tree grate should be removed to observe the bioretention bay. Any trash and debris that has collected here should be removed and disposed of appropriately. As with all media filtration systems, captured pollutants and sediments will accumulate on the surface of the engineered soil mixture over time, reducing the treatment capacity of the system. If captured pollutants are observed to have occluded the media surface, or if standing water is present in the biofiltration bay during dry periods, then maintenance of the top layer of soil mixture is required. Studies have shown that the majority of all captured pollutants reside in the top 2-3 inches of soil and therefore it is likely that only this layer needs to be replaced. (California Stormwater Quality Association (CASQA), New Development and Redevelopment Handbook, January 2003). Replacement soil is available from CONTECH. Please note that when replacing the engineered soil mixture, the energy dissipation rocks which protect the inlet from scour should be collected and set aside for use with the new soil. Once the new soil has been installed, the energy dissipation rocks should be placed back at the inlet. Once the bioretention bay has been inspected and maintenance procedures completed, the tree grate placed should be put securely back in place. As part of the standard terms of system purchase, CONTECH will supply routine maintenance services as described herein within approximately 1 year of system activation. Associated maintenance log records will be made available to the owner upon request. Inspection and maintenance of the media cartridge bay are also critical to the overall performance of the system. Inspection should be performed at the same time as inspection of the bioretention bay. Remove the cover over the media cartridge bay and observe the accumulated pollutants within the chamber. If more than three inches of sediment is found on the chamber floor or on the tops of the cartridges, then cartridge replacement should be performed. Additionally, if standing water resides in the chamber for greater than twenty-four hours after a storm event, then cartridge replacement should be performed. Depending on site and climatic conditions, maintenance frequency of the media cartridges should range from 3 to 5 years. Instructions for cartridge replacement are provided in the Non-Routine Maintenance section below. All observations from inspection of the media cartridge bay should be recorded in the maintenance log. Non-Routine Maintenance Non-routine maintenance is defined as clean-out of the media cartridge bay and replacement of cartridges. Replacement cartridges can be ordered by contacting CONTECH at 800.338.1122. The first step in the clean-out of the media cartridge bay is to remove the sediment and debris that has collected in this chamber. A vacuum truck or manual operation can be used for this procedure. Once the sediment and debris has been removed, the existing cartridges should be removed from the system. Cartridges are connected to the underdrain manifold by a simple quarter-turn connection and are easily disconnected. Once the cartridges are removed from the vault, any remaining sediment and/or debris should be cleaned out. The final step in the cartridge replacement process is to install the replacement cartridges. Replacement cartridges should be installed securely to the quarter-turn connection system and the cover placed securely back over the media cartridge bay. General Maintenance Notes All OSHA standards for health and safety should be followed at all times when inspecting or maintaining the UrbanGreen BioFilter. Furthermore, disposal of pollutants removed from the UrbanGreen BioFilter should be performed in accàrdance with all regulatory requirements. UrbanGreen BioFilter Inspection & Maintenance Log Project Name: Date of Installation: Location: Date Tree Height/Width/ Condition Bioretention Bay Routine Maintenance Performed Media Cartridge Bay Observations Media Cartridge Bay Maintenance Performed UrbanGreen BioFilter Inspection & Maintenance Log Project Name: Walmart Date of Installation: 10/01/05 Location: Anywhere, USA Date Tree Media Media Cartridge 1iP Condition 12101/06 367247good condition Removed debris from chamber Slight Sediment layer on floor None required 12/01/07 38/287good condition Removed debris /replaced V of sediment on floor None required soil top layer 12/01/08 427327/needs irrigation Removed debris from chamber 1 1/2' of sediment on floor None required 12101/09 47I38/good condition Removed debris from chamber 2" of sediment on floor None required 12/01/10 507/397/good condition Removed debris /replaced 2 1/4" of sediment on floor None required soil top laye 12/01/11 527427/needs irrigation Removed debris from chamber 2 1/2" of sediment on floor None required 12/01/12 54"/40"/good condition Removed debris from chamber/ 3" of sediment on floor Chamber cleaned/ replaced soil top laye cartridges replaced CONTECH ENGINEERED SOLUTIONS 020I2 CONTECH ENGINEERED SOLUTIONS, U.C. 800.338-1122 wew.conteclrE5.com All Rights Reserved. Printed in the USA. CONTECH Engineered Solutions, U.C. pronides site solutions for the dm1 engineering industry. CONTECH's portfolio Includes bridges, drainage, sanitary sewer, ston'nwaler and earth stabilization products. For information on other CONTECH division offerings, sott con?ech-cpl.conr or coil 800.338.1122 The product(s) described may be proteded by one or more of the following US patents: 5,322,629; 5,624,576; 5,707,527; 5,759,415; 5,788,848; 5,985,157; 6.027,639; 6.350,374; 6,406,218; 6,641,720; 6,511,595; 6,649,048; 6,991,114; 6,998,038; 7,186,058; 7,296492; 7,297,266; related foreign patents or other patents pending. ub_bf_maintenance 02/12 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. SEE THE CONTECH STANDARD CONDITIONS OF SALE (VIEWABLE AT WWW.CONTECH-CPI.COMJCOS) FOR MORE INFORMATION. We print our brochures entirely on Forest Stewardship Council certified paper. FSC FSC certification ensures that the paper in our brochures contain fiber from well- managed and responsibly harvested forests that meet strict environmental and socioeconomic standards. ATTACHMENT 5 BIORETENTION BASIN -SPECIFICATIONS AND DETAILS PER PLANNED INDUSTRIAL PERMIT 133/15 S/HI ,5310N N0/IN3YO/8 335 37Y.25 01 ION MSV6' HL Y2 I V MS VS N011N31380/S 7 YOU (I SNOII YCN3/WYO.234Y 7Y.2/NH.231030 83d (M,'v 7/fr? of) 7Y3S 1/1911 -831 VAI 3014Oëd 01 G30 734f SI MOP /M fY3M7 3dGH 378V3/Y83c/ft/ 77YISN/ 7Vf7O3 80 NOfri 1YY8/iI( 133/IS S/HI 7/VI39 83c/ 3.2/3/80 7081N0.2 AIO 73 C3/3/GO1V - c/V8 d/8 133H5 S/HI 7/VIJC 83d-"\ .4 Y41 77/c/S. 3138.2/VO.9 '\ SNO/I VC/VPWVO.238 7V.2/NH.231039 83c/ (N //v 7'iv or) 7 V3 1/10/1-831 Of 394108d 01 G307341 SI MOP IN 83M7 3dGH 378V3iY83diV/ 77VISM 833N/.9N3 7V.2/NH.231030 AS 031_4/834 3501 31 MY NO/I V(Yi 7/3M 8170H 1/H.2M c '731 Y8.9 t/c (IN3e3Ji/0 3/ NV7d NO NAIOHS H) M/v,.9 —734 V8.9 V3d,fr - X//If IS0c/frYO.2/GNVS ,. NV7c/ 83d 0310N SV Id3.2XJ VWV NO/IN3i380/9 S7V/?03 i'98V 83AV7 731 3a'075 N/fr? Xl \O MV808301VI? - G3I V80J83c/ , fr 1N3i?3AYc/ J A-- N/iY0l1 Mi? — 91 77/3 1931.2Vc/fr?O.2 N/frI( I NV7c/ d/3d MSV9 /1.21 V.2 " NY7d 83d 53/8 VA HR/MI V38V cc)l Nd83dS3/8VAH - , I 08V053383 9 OS 1 N/fr? ,Of /V831(V7 734V89 3c/O 75 N//V Xl MV8G83GNfl 031 V80J83c/ .,fr N//V '1 49 - 833N/.9N3 7V.'/NH.13iO3D AS IR 03/J/831 4'S 01 31 V8 NO V81 7/Jiy/ : --i 8flOH l/H.)N/ c '731 V89 fr/f -j (INjy3ji/c i/ NV7d NO NAIOHS H) N//V ,9 SIVOII VCNJ/WVO[)38 7V.2/NH.'3103.9 ê13d (lW/V 7//V or) 7 V3 1/1.211-831 YM 3G140&/ 01 03G 73H SIN/OP /41 cY3N/7 3c/CH 378V3/V83d/V/ 77V15A SNO/I VCNJ/V/VO.238 7V.)/NH.73103.2 ?JJd ON An or) 7V35 1/1.2/1-811 Vhf 31fr10ëd 01 G3073l SI MOP IN - 83M7 3d0H 378V3/V83d/W 77VISM I33HS S/Hi .SJION N011N31380/8 335 37X25 01 ION MSVS N011N31380/8 7V2/cP'J NV7d 83d CJION SV I dV8c//84 .133H5 S/Hi 7/V130 83d—.... A V%1 77/c/S 3I38.2NO.) N//V,101 1 N//V = .9l -731 V89 V3o'fr X//V 1SOc//V0..?/0NVS frc 77/i 0310Vd/V0.2 ft;. IN3/Y3AVd ' N//V L 08V08338J 9 NV7c/ 83d 53/8 VA /110/41 V38V NO/1N3138108 N//V Of NV7d 83c/ 53/b'VA ATTACHMENT 6 BIO CLEAN TRENCH FILTER INSERT Ili-IlIFIL 111111 iii:ii For use in Standard Trench Drains Ideal for Gas Stations and Maintenance Yards Captures Hydrocarbon (Oil and Grease) Easy Maintenance and Replacement of Hydrocarbon Booms Also Captures Trash and Litter Treats Entire Flow Manufactured from Marine Grade Fiberglass with UV Protection Available in 4 Foot Sections The Flow Rate is 0.064cf5 per foot. For Instance, a 10 foot long trench filter will flow O.64cfs. Bio Clean Trench Drain Filter is especially designed for high levels of hydrocarbon, oils and grease. It will also capture trash, litter, sediments and organics. The medium is both absorbent and absorbent attracting hydrocarbon to the polymer service for adsorption. -. Marine Grade High Durability UV Protected Fiberglass Custom Manufactured for Exact Fit Hydrocarbon Boom P 0 Box 869, Oceanside, CA 92049 B10 CLEAN 4 (760) 433-7640 • Fax (760) 433-3176 "The Stor water Standard" ENVIRONMENTAL SERVICES. INC www.biocleanenvironmental.net SPECIFICATIONS Trench Drain Filter I. Specifications Coverage: The Trench Drain Filter provides full coverage of trench drains, at rated flows, is conveyed to the filter. The filter will retain all windblown and swept debris entering the drain. The Trench Drain Filter is located directly beneath the trench drain grate for direct service/access from the surface. The filter is made to direct water flow from the trench grate through the filter media before entering the trench unit. Non-Corrosive Materials: All components of the filter system, including mounting hardware, fasteners, support brackets, filtration material, and support frame are constructed of non-corrosive materials. The frame is manufactured of marine grade fiberglass, gel coated for UV protection. No polypropylene, monofilament netting or fabrics shall be used. Durability: Filter (excluding oil absorbent media) and support structures are of proven durability, with an expected service life of 10 to 15 years. The filter and mounting structures are of sufficient strength to support water, sediment, and debris loads when the filter is full, with no slippage, breaking, or tearing. All filters are warranted for a minimum of five (5) years. Oil Absorbent Media: The Filter is fitted with Bio Sorb, an absorbent media for removal of petroleum hydrocarbons from influent, and so placed in the filter assembly to treat influent at rated flow. Absorbent media is easily replaceable in the filter, without the necessity of removing fixed mounting brackets or mounting hardware. Filter Bypass: Water will not bypass the filter inlet contact surfaces at low flows. Pollutant Removal Efficiency: The filter Is designed to capture high levels of trash and litter, grass and foliage, sediments, hydrocarbons, grease and oil. The filtered flow maximum capacity is 0.064 cfs per foot. Filter Media Replacement: Removal and replacement of the booms containing the absorbent media is accomplished without the necessity of removing mounting bolts, support frames, etc. Filter Removal: The filter is readily removable from the trench drain for maintenance or replacement without the necessity of removing mounting bolts, support frames, etc. II. Installation Installation: The filter will be securely installed in the trench drain, with contact surfaces sufficiently joined together so that no filter bypass can occur at low flow. All anchoring devices and fasteners are installed within the interior of the drain inlet. Installation Notes: Bio Clean Environmental Services, Inc. inlet filter inserts shall be installed pursuant to the manufacturer's recommendations and the details on this sheet. Inlet filter insert shall provide coverage of entire trench inlet opening The Trench Filter is installed by lifting the grate and inserting the filter so the filter lip sits underneath the grate The filter is manufactured so the sections overlap each other for easy installation. III. Maintenance Maintenance: The filter is designed to allow for the use of manual or vacuum removal of captured materials in the filter structure. The filter is serviceable manually or by centrifugal compressor vacuum units without causing damage to the filter during normal cleaning and maintenance. Filters can be cleaned easily by simply removing the grate to expose access to the filter. The hydrocarbon booms then are removed and the trash and debris can be removed from the structure. At each cleaning, new hydrocarbon booms should be installed by placing in the filter. Maintenance Notes: Bio Clean Environmental Services Inc. recommends cleaning and debris removal maintenance a minimum of four times per year, and replacement of hydrocarbon booms a minimum of twice per year. Following maintenance and/or inspection, the maintenance operator shall prepare a maintenance/inspection record. The record shall include any maintenance activities performed, amount and description of debris collected, and condition of filter. The owner shall retain the maintenance/inspection record for a minimum of five years from the date of maintenance. These records shall be made available to the governing municipality for inspection upon request at any time. For maintenance and cleaning remove grate to gain access to inlet filter insert. Where possible the maintenance should be performed from the ground surface. Note: entry into an underground stormwater vault such as an inlet vault requires certification in confined space training. Remove all trash, debris, organics, and sediments collected by the inlet filter insert. Evaluation of the hydrocarbon boom shall be performed at each cleaning. If the boom is filled with hydrocarbons and oils it should be replaced. Transport all debris, trash, organics and sediments to approved facility for disposal in accordance with local and state requirements. The hydrocarbon boom is classified as hazardous material and will have to be picked up and disposed of as hazardous waste. Hazardous material can only be handled by a certified hazardous waste trained person (minimum 24-hour hazwoper). B10 CLEAN P 0 Box 869, Oceanside, CA 92049 (760 433-7640 Fax (760) 433-3176 ENVIRONMENTAL SERVICES. INC www.biocleanenvironmental.net !ORE I- a" To 10" 314x3 I- 16" IL—c I- 8" r rj MODEL # 4.5 - 8 'OR MORE F---6"T08" 1 FOR ODD SIZE TRENCHES FLANGES CAN BE CUT WITH ALMOST ANY SKILL A W WIT-F-1 CA F B I C) B LA C) / L I Iv! C) 0 E L_ # -.5 - 1.2 11k" a.I TO INSTALL SIMPLY REMOVE GRATE PLACE IN INLET FILTER AND REINSTALL GRATE TO ITS ORIGINAL LOCATION TREATMENT FLOW RATE = .064 CFS PER LINEAR FOOT 760-433-7640 TO INSTALL THE MODEL. 4.5-8 IN A SMALLER OPENING SUCH AS SHOWN INSTALL .3'4" ANGLE WITH 7 ,'4" DRIVE PINS. I" I t.I L... 7 .I LT .Ti-=, -rc> I -7 'OR MORE k-6"TOa" -1 TO INSTALL SIMPLY REMOVE GRATE PLACE IN INLET FILTER AND REINSTALL GRATE To ITS ORIGINAL LOCATION r # ,—i c i . -r- i=-i I n_ MODEL # 4.5 - 8 TREATMENT FLOW RATE = .064 CFS PER LINEAR roorl 8" FOR ODD SIZE TRENCHES FLANGES CAN BE CUT WITH ALMOST ANY SKILL A W WIT-1--I CA F B! C) B LA C) 3%X4 H 8" .rl To INSTALL THE MODEL 4.5-0 IN A SMALLER OPENING SLJCI-i AS SHOWN INSTALL .34." ANGLE WITH 7 ,.'4." DRIVE PINS. L..A E I" I P.1 L. T FI L...rE ^"I=) I P.1 r,-&.L-L- 7 I r I1 I P.J. L L P.4 TO INSTALL SIMPLY REMOVE CRATE PLACE IN INLE-r FILTER AND REINSTALL GRATE TO ITS ORIGINAL LOCATION 760-4.3.3-7640 I—I i I / L I F tvl C) C) E L_ # - 1 2 TREATMENT FLOW RATE = .064 CFS PER LINEAR FOOT I.. 11" •1 FORE I- 8" To 10" FOR ODD SIZE TRENCHES FLANGES CAN BE CUT WITH ALMOST ANY SKILL 1A W W/7-1-4 CA I 8/ C) B LA C) I. 16° SOCK 6" TO INSTALL THE MODEL . - 1 .2 IN A WIDER OPENING SUCH AS S)-IOWN INSTALL .3,'4" ANGLE WITH I ,4" DRIVE PINS. 1._A I t%J I FJ 1.... T FI L7 _ E I f.J -r L L r r I-7 I I tIA L L rI