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MS 05-29; ADAMS STREET SUBDIVISION; PRELIMINARY STORM WATER MANAGEMENT PLAN; 2008-04-09
PRELIMINARY STORM WATER MANAGEMENT PLAN For ADAMS STREET. (PORTION OF LOTS 5 & 6 OF MAP 2152) MS 05-29 RECEIVED Revised: April 9, 2008 Revised: December 10, 2007 Revised: May 14, 2007 Revised: November 7, 2006 Revised: September 14, 2006 Prepared: October 1, 2005 JN 05-1139 Prepared By: O'DAY CONSULTANTS 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010 CITY OF CAR LSBAD PLANNING DEPT Meg RCE 46935 Date Prepared by: PMK, RB 1 G:\051139\SWMP\Storm Water Management Plan.doc PRELIMINARY STORM WATER MANAGEMENT PLAN For ADAMS STREET (PORTION OF LOTS 5 & 6 OF MAP 2152) MS 05-29 PWA Revised: April 9, 2008 Revised: December 10, 2007 Revised: May 14, 2007 Revised: November 7, 2006 Revised: September 14, 2006 Prepared: October 1, 2005 iN 05-1139 Prepared By: O'DAY CONSULTANTS 2710 Loker Avenue West, Suite 100 Carlsbad, CA 92010 Meg Carroll RCE 46935 Date Prepared by: PMK, RB 1 C:\05 11 39\SWMP\Storm Water Management Plan.doc TABLE OF CONTENTS 1.0 PROJECT DESCRIPTION......................................................................3 1.1 Hydrologic Unit Contribution..............................................................3 1.2 Beneficial Uses ........................................................ 4 2.0 CHARACTERIZATION OF PROJECT RUNOFF.........................................4 2.1 Soil Characteristics..........................................................................4 2.2 Potential Discharges..........................................................................4 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY.......................5 3.1 Site Design BMP's .......................................................................... 5 3.2 Source Control BMP's......................................................................6 3.3 Treatment Control BMP's .................................................................... 6 3.4 Construction BMPs..........................................................................7 4.0 MONITORING, INSPECTION, AND REPORTING ....................................... 7 5.0 ESTIMATED MAINTENANCE COSTS ....................................................8 6.0 SIZING CALCULATIONS FOR INLET FILTER & INFILTRATION TRENCH. . . .8 Attachments: Vicinity map Beneficial uses for the hydrologic unit 303(D) list for impaired water bodies Table 2: Anticipated and potential pollutants Table!: Storm Water BMP Requirements Matrix Table 3: Treatment Control BMP Selection Matrix Project site plan & BMP map Site Design BMPs Source Control BMPs Treatment Control BMPs BMP Sizing Calculations - Table 3: Numeric Sizing Treatment Standards Appendix H of county SUSMP San Diego County Soils Interpretation Study: Hydrologic Soil Groups - Runoff Potential 2 G:\051139\SWMP\Storm Water Management Plan.doc STORM WATER MANAGEMENT PLAN Federal, state and local agencies have established goals and objectives for storm water quality in the region. The proposed project, prior to the start of construction activities, will comply with all federal, state and local permits including the Stormwater Management Plan (SWMP) required under the County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance (WPO) (section 67.87 1), the City of Carlsbad's Standard Urban Storm Water Mitigation Plan, and the National Pollution Discharge Elimination System (NPDES) from the Regional Water Quality Control Board (RWQCB). The purpose of this SWMP is to address the water quality impacts from the proposed improvements as shown on the Tentative Parcel Map. This project will provide guidelines in developing and implementing Best Management Practices (BMPs) for storm water quality during construction and post construction. Since the site is more than 1 acre, a Storm Water Pollution Prevention Plan (SWPPP) will be required. A SWPPP will be prepared and approved prior to issuance of a grading permit. The approved SWPPP shall be implemented during the construction phase. The SWPPP will consist of the selected BMPs, guidelines and activities to carry out actions, which will prevent the pollution of storm water runoff. The SWPPP will also include the monitoring and maintenance of the construction BMPs during the construction phase. 1.0 PROJECT DESCRIPTION The project site is located in the City of Carlsbad southeast of the intersection of Highland Drive and Adams Street (see Vicinity Map, attachment 1). The site is to be divided into one shared driveway parcel, one open space parcel, and two Single Family Residential parcels. 1.1 Hydrologic Unit Contribution The project is located in the Batiquitos Hydrologic Sub-area (904.51) of the San Marcos Watershed in the Carlsbad Hydrologic Unit in the San Diego Region. Under existing conditions, storm runoff flows from Adams Street are drained toward the North-Easterly side of the street to an existing ditch. Flows from the Northerly portion of the subdivision concentrate into a separate natural drainage course and are then conveyed southerly to the subdivision boundary, where they flow offsite to the open space parcel to an existing watershed. The proposed project will not alter the drainage discharge patterns on site. Subdivision improvement will adjust drainage basin boundaries, but in such a way as to control and mitigate increases in runoff within each basin. 3 G:\051139\SWMP\Storm Water Management Plan.doc 1.2 Beneficial Uses The beneficial uses for the hydrologic unit are included in attachment 2, and the definitions are listed below. This information comes from the Water Quality Control Plan for the San Diego Basin. REC 1 —Contract Recreation: Includes uses of water for recreational activities involving body contact with water, where ingestion of water is reasonably possible. These uses include, but are not limited to, swimming, wading, water-skiing, skin and SCUBA diving, surfing, white water activities, fishing, or use of natural hot springs. REC 2—Non-Contact Recreation: Includes the uses of water for recreational activities involving proximity to water, but not normally involving body contact with water, where ingestion of water is reasonably possible. These include, but are not limited to, picnicking, sunbathing, hiking, camping, boating, tide pool and marine life study, hunting, sightseeing, or aesthetic enjoyment in conjunction with the above activities. EST - Estuarine Habitat: Includes the uses of water that support estuarine ecosystems including, but not limited to, preservation or enhancement of estuarine habitats, vegetation, fish, or wildlife (e.g., estuarine mammals, waterfowl, shorebirds). MAR —Marine Habitat: Includes uses of water that support marine ecosystems including, but not limited to, preservation or enhancement or marine habitats, vegetation such as kelp, fish, shellfish, or wildlife (e.g., marine mammals, shorebirds). WILD —Wildlife Habitat: Includes uses of water that support terrestrial ecosystems including but not limited to, preservation and enhancement of terrestrial habitats, vegetation, wildlife, (e.g., mammals, birds, reptiles, amphibians, invertebrates), or wildlife water food and sources. RARE - Rare, Threatened, or Endangered Species: Includes uses of water that support habitats necessary, at least in part, for the survival and successful maintenance of plant or animal species established under state or federal law as rare, threatened or endangered. 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. 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. 2.0 CHARACTERIZATION OF PROJECT RUNOFF According to the California 2002 303(d) list published by the RWQCB (attachment 3), Agua Hedionda Lagoon is an impaired water body associated with the direct stormwater discharge from this project. Agua Hedionda Lagoon has low priority impairment for Bacteria indicators and sedimentation/siltation. 2.1 Soil Characteristics The project area consists entirely of soil group A. (See Attachment 13) 2.2 Potential Discharges There is no sampling data available for the existing site condition. The project will contain some pollutants commonly found on similar developments that could affect water quality. The following list is 4 G:\051139\SWMP\Storm Water Management Plan.doc taken from Table 2 of the City of Carlsbad's Storm Water Standards Manual (attachment 4). It includes anticipated pollutants for Detached Residential Development and Hillside Development. Detached Residential Development Hillside Development . Nutrients from fertilizers • Nutrients from fertilizers Trash and debris • Trash and debris Oxygen demanding substances • Oxygen demanding substances Oil and grease from paved areas . Oil and grease from paved areas Bacteria & Viruses • Pesticides from landscaping Pesticides from landscaping 3.0 MITIGATION MEASURES TO PROTECT WATER QUALITY To address water quality for the project, BMPs will be implemented during construction and post construction. Required BMPs are selected from Table 1: Storm Water BMP requirements Matrix, of the City of Carlsbad's Storm Water Standards Manual (attachment 5). 3.1 Site Design/Low Impact Development (L.I.D.) BMP's Control of post-development peak storm water runoff discharge rates and velocities is desirable in order to maintain or reduce to pre-development downstream erosion by applying the following concepts (see attachment 8 for details): Residential Development: Establishing planning areas for two single families accomplishes several desirable effects. Drainage systems service only developed areas reducing the amount of debris, siltation, and sedimentation associated with natural drainage courses. Natural drainage courses are preserved maintaining existing hydrologic regimes. Infiltration trenches are placed with distributed outlets minimizing flow concentrations and velocities. Conserve Natural Areas: The areas chosen for development are clustered on the least environmentally sensitive land. The open space lot will be left in a natural, undisturbed condition. Minimize Directly Connected Impervious Areas: To the maximum extent, practicable patios, rooftop drains, rain gutters and other impervious surfaces shall drain into adjacent landscaping and infiltration trenches prior to discharging to the storm water conveyance system. Concrete patios shall be made of pervious pavement to reduce the overall flow from the site. Vegetated/Grass Swale: Using vegetated/grass swales generates an aesthetically pleasing form of drainage integrated with the natural features of the site and also helps the process of infiltration, retention/detention and bio-filtration. Protect Slopes and Channels: All runoff will be safely conveyed away from the tops of slopes. 5 G:\051139\SWMP\Storm Water Management Plan.doc Install Energy Dissipaters (Infiltration Trench): Infiltration trenches shall be installed at the ends of certain vegetated/grass swales and directly before water is outlet to the undeveloped terrain in accordance with applicable standards and specifications to minimize erosion. The infiltration trenches will be placed behind retaining walls and will have a perforated PVC pipe to help disperse flow to a series of weep holes in the walls. The infiltration trenches will also act as small detention basins to further minimize runoff concentrations and increase infiltration. 3.2 Source Control BMP's Source Control BMPs help minimize the introduction of pollutants into storm water in order to maintain or reduce pre-development levels of pollutants by applying the following concepts (see attachment 9 for details): Street Sweeping: Private parking lots and city maintained streets will be swept routinely in order to reduce introduction of trash, debris, sediment and siltation into drainage systems. Trash Storage Areas to Reduce Pollution Introduction: This is a detached residential development project with lidded curbside trash containers. Use Efficient Irrigation Systems & Landscape Design: Irrigation systems shall employ rain shutoff devices to prevent irrigation during precipitation, be designed to each landscape area's specific water requirements consistent with the Carlsbad Landscape Manual and employ drip irrigation to minimize runoff. Provide Storm Water Conveyance System Stenciling and Signage: All storm water conveyance inlets shall provide concrete stamping, porcelain tile, inset permanent marking or equivalent as approved by the City of Carlsbad within the project area with prohibitive language satisfactory to the City Engineer. 3.3 Treatment Control BMP's As identified in Table 1 (attachment 5), a combination of treatment control BMP's shall be incorporated into the project. The project has been designed so that runoff is treated by Site Design BMP's prior to Structural Treatment BMP's. Treatment control BMP's were selected by comparing a list of pollutants for which the receiving water bodies are impaired to a list of expected pollutants for each basin. A combination of Vegetated Swales, Inlet Filters and infiltration trenches were chosen and will provide maximum pollutant removal efficiency for anticipated pollutants. As per Tabl (attachment 6), infiltration trenches (LID) have a high removal efficiency for course sediment and trash, pollutants that tend to associate with fine particles during treatment and pollutants that tend to be dissolved following treatment. Inlet filters or Trash racks & Hydro-dynamic Devices have a low removal efficiency for pollutants that tend to be dissolved following treatment and pollutants that tend to associate with fine particles during treatment but a high removal efficiency for coarse sediment and trash. Vegetated Swales (flow- through planters (LID)) are considered to have a high removal 6 G:\051139\SWMP\Storm Water Management Plan.doc efficiency for coarse sediment and pollutants that tend to associate with fine particles and a medium removal efficiency for pollutants that tend to be dissolved during treatment. The Treatment BMPs selected are shown in Attachment 10. 3.4 Construction BMPs The following is a list of potential construction phase BMPs to be used. Silt fence, fiber rolls, or gravel bag berms Check dams Street sweeping and vacuuming Storm drain inlet protection Stabilized construction entrance/exit Vehicle and equipment maintenance, cleaning, and fueling Hydroseed, soil binders, or straw mulch Material delivery and storage Stockpile management Spill prevention and control Waste management for solid, liquid, hazardous and sanitary waste, contaminated soil. Concrete waste management A SWPPP will be prepared and approved prior to issuance of a grading permit. Construction BMPs for this project will be selected, constructed, and maintained through the SWPPP to comply with all applicable ordinances and guidance documents. The approved SWPPP shall be implemented during the construction phase. 4.0 MONITORING, INSPECTION, AND REPORTING During construction, the BMPs will be monitored on a weekly basis, and observations recorded on the included checklists (see last page). The Owner and Developer will be responsible for the monitoring and maintenance of the BMPs. OWNERS: Dr. Ben & Eunice Medina 5190 Choccliff Bonita, CA 91902 (760)-931-0780 Dr. David Graham 305 E 8th St National City, CA 91950 (760)-931-0780 7 G:\051139\SWMP\Storm Water Management Plan.doc 5.0 ESTIMATED MAINTENANCE COSTS Please see attachment 12 for a copy of Appendix H of County's SUSMP titled "Estimated O&M Costs for BMP Project". Applicable costs are listed below. Maintenance activities are listed in Attachment H. BMP Total Annual Cost for Maintenance (See Attachment H) Infiltration Trench $3,099.52 Vegetated Swale - Biofilter $2,972.42 Drain Inlet Inserts $1,183.40 Total: $7,255.34 6.0 SIZING CALCULATIONS FOR INLET FILTER & INFILTRATION TRENCH Please see Table 3, Attachment 11 for sizing treatment standards. Please see Bio Clean inlet filter engineering drawing, Attachment 11 for filter flow specifications. Please see Attachment 7 for Inlet Filter location. Please reference the Preliminary Drainage Study for Adams Street by O'Day consultants, dated May 4, 2007 for average 'C' values and basin areas leading to the inlet filter. Inlet Filter: Using method 2, the flow based method for sizing, rainfall intensity, I = 0.2 in/hr Q=CIA Q = (0.77)*(0.2)*(0.126) = 0.02 CFS Per the Bio Clean filter specifications in Attachment 11, an 18"x 18" inlet filter can accommodate 5.0 CFS. 5.0 CFS >> 0.02 CFS The 18"x 18" Bio Clean inlet filter per Attachment 11 is sufficient. Infiltration Trenches: (For detention calculations and times for 100-year proposed condition see Preliminary Drainage Study for Adams St. (Portion of Lots 5 & 6 of Map 2152) May 4, 2007) Basin 1: Water Quality Volume, WQV = (0.6")*(Basin Area) = (0.6/12)*(0. 159*43560) = 346 ft3 8 G:\051139\SWMF\Storm Water Management Plan.doc To find the trench depth, dm11 = (35%)*WPV I Lw = (.35)*(346)/(42*4) = 0.72 ft davg = (0.5)dfull = 0.36 feet In 72 hours, calculate the WQV drained through infiltration, WQV1: Qp (1/3)Ldavg f, where f=2.7"/hr Qp = (1/3)*42*.36*(2.7/12) = 1.13 ft3/hr 72hr = WQV1/Qp WQV1 =72*1.13 WQV1 = 81.6 ft3 The remaining volume, VR = WQV - WQVI = 346-81.6 = 264.4 ft3 will be drained by the perforated pipe, calculated from orifice flow. Qpjp=[C0Ao(2g*h)^.51*N, where N = number of holes in pipe per hydrology study Q=[3.068*10(64.4*.03)A.51*(189*.35) = 0.28 CFS *3600 = 101.6 ft3/hr VR/Qp1 = time = 264.4/10 1.6 = 2.6 hours <72 hours 3 OK Basin 2A: Water Quality Volume, WQV = (0.6")*(Basin Area) = (0.6/12)*(0.024*43560) = 52 ft3 To find the trench depth, dfIt = (35%)*WPV / L*w = (.35)*(52)/(16*3) = 0.38 ft davg = (0.5)dr11 = 0.19 feet In 72 hours, calculate the WQV drained through infiltration, WQV1: Qp = (1/3)Ldavgf, where f=2.7"/hr Qp = (1/3)*16*.19*(2.7/12) = 0.23 ft3/hr 72hr = WQV1/Qp WQV1 = 72*0.23 WQV1 = 16.6 ft3 The remaining volume, VR = WQV - WQV1 = 52-16.6 = 35.4 ft3 will be drained by the perforated pipe, calculated from orifice flow. Qpjp=[C0Ao(2g*h .51*N, where N = number of holes in pipe per hydrology study for Adams St. Q=[3.068*104(64.4*.03)A.5]*(16*.35) = 0.0024 CFS *3600 = 8.6 ft3 /hr VR/Qp = time = 35.4/8.6 = 4.12 hours <72 hours 4 OK Basin 2B: Water Quality Volume, WQV = (0.6")*(Basin Area) = (0.6112)*(0.045*43560) =98 ft3 9 G:\051139\SWMP\Storm Water Management Plan.doc To find the trench depth, d 11 = (35%)*WPV / L*w = (.35)*(98)/(53*3) = 0.22 ft davg = (0.5)dfu11 = 0.11 feet In 72 hours, calculate the WQV drained through infiltration, WQV1: Qp = (1/3)Ldavgf, where f=2.7"/hr Qp = (1/3)*53*.11*(2.7/12) = 0.44 ft/hr 72hr = WQV/Qp WQVI = 72*0.44 WQV1 = 31.7 ft3 The remaining volume, YR = WQV - WQV1 = 98-31.7 = 66.3 ft3 will be drained by the perforated pipe, calculated from orifice flow. Qpjp=[C0A0(2g*h)Pt.5]*N, where N = number of holes in pipe per hydrology study for Adams St. Q=[3.068*104(64.4*.03)A.5]*(13*.35) = 0.0019 CFS *3600 = 7.0 ft3/hr VR/Qpipe = time = 66.3/7.0 = 9.47 hours <72 hours 3 OK Basin 2C: Water Quality Volume, WQV = (0.6")*(Basin Area) = (0.6112)*(0.016*43560) = 35 ft3 To find the trench depth, dfII = (35%)*WPV / L*w = (.35)*(35)I(12*3) = 0.34 ft davg = (0.5)dfull = 0.17 feet In 72 hours, calculate the WQV drained through infiltration, WQV1: Qp = (1/3)Ldavgf, where f=2.7"/hr Qp = (1/3)*12*.17*(2.7/12) = 0.15 ft3/hr 72hr = WQV1/Qp WQVI = 72*0.15 WQV1 = 10.8 ft The remaining volume, VR = WQV - WQVI = 35-10.8 = 24.2 ft' will be drained by the perforated pipe, calculated from orifice flow. Qpjp=[C0A(2g*h.5]*N, where N = number of holes in pipe per hydrology study for Adams St. Q[3.068*10(64.4*.03)ø\.5]*(12*.35) = 0.0018 CFS *3600 = 6.45 ft3/hr VR/Qpipe = time = 24.2/6.45 = 3.75 hours <72 hours - OK Basin 5: Water Quality Volume, WQV = (0.6")*(Basin Area) = (0.6/12)*(0.089*43560) = 194 ft3 10 G:\051139\SWMP\Storm Water Management Plan.doc To find the trench depth, d111 = (35%)*WPV / L*w = (.35)*(194)I(51*3) = 0.44 ft day5 = (0.5)diwi = 0.22 feet In 72 hours, calculate the WQV drained through infiltration, WQV1: Qp = (1/3)Ldavgf, where f=2.7"/hr Qp = (1/3)*5 1 *.22*(2.7/12) = 0.84 ft3lhr 72hr = WQV1/Qp WQV1 =72*0.84 WQV1 = 60.5 ft3 The remaining volume, YR = WQV - WQVI = 194-60.5 = 133.5 ft3 will be drained by the perforated pipe, calculated from orifice flow. Qpjp[CAo(2g*h.5]*N, where N = number of holes in pipe per hydrology study for Adams St. Q=[3.068*104(64.4*.03)A.5]*(51*.35) = 0.0076 CFS *3600 = 27.4 ft3/hr VR/Qpj = time = 133.5/27.4 = 4.87 hours <72 hours 3 OK 11 G:\051139\SWMP\Storm Water Management Plan.doc Attachment 1 CITY OF IIGHWAYL 4;jT E VILLAGE Lp IGH- HILLSID LAND -DR. DR. ADAMS AGUA ST. HEDIONDA LAGOON CITY OF - PALOMAR L CITY OF VISTA PACIFIC OCEAN LL ( CITY OF SAN MARCOS VICINITY MAP NO SCALE 01 Attachment 2 Table 2-3. BENEFICIAL USES OF COASTAL WATERS Hydrologic Unit Basin Number BENEFICIAL USE Coastal Waters T N DV A CC 1 2 MO 1 ML — T — T T — W L 0 ft E ft U A G A W N ft M E L L L paciticOcean _____ _ ... . 9 01 Doria Point Haubor • • • • • • • • • Dal Mar 8uatBasin MisonBay • • • • • • • 0 01 OceanicieHarbor • • • • • • • • 01 • 01 Sian Dle9oflay Coastal Lagoons 0 1 Tijuana River Estuary 11.11 . . . S 0 S 0 0 S Mouth of San Diego River 7.11 - - • • • • • • • - - - Lob PensquatosLagoon 2 6.10 . . S San Dieguito Lagoon 5.11 0 0 0 0 . . tsqustos Lagoon 4.51 610 0 . 0 . SiiElijoLa9oon 5.61 . e 10 . . . Aqua hedionda Lagoon 4.31 S S . . = = = = S Is itAudab the taddi prisnu of the Otay and Sweetwater Rivers. ' h.lsiisg from shore or boat permitted, but other water contact recreational LREC-1) uses are prohibited. Emutinij beneficial Use ;e bItithCIL ut 2.47 September 8. 1994 Table 2-2. BENEFICIAL USES OF INLAND SURFACE WATERS • Hydrologic unit Basin Number BENEFllAL USE Inland Surface Waters 1.2 M U N A G R I N 0 P R 0 C 6 W R F ft S H P 0 W ft E C 1 ft S C 2 B I 0 L w A H MD C 0 L W I L 0 R A ft 5 S P W N San Diego County Coastal Streams - conti.wsd Buema Vista Lagoon 4.21 See Coastal Waters- Table 2-3 buena Vista Creek 4.22 + 0 1 0 1 1 . buena Vista Crook 4.21 + I L 1 1 0 1 01 . Aqua I*dionda 4.31 See Coastal Waters- Table 2-3 - - - Aqua Hedionda creek 4.32 . Buena Creek 4.32 S • - - - - l- oi- - Ajua Hedionda Creek 4.31 . 0 S - Letterboxcenyon 431•S _ CenyondeIisEncjnas 4.40 + 0 l e San Marcos Creek Watershed &atiquilos Lagoon 4.61 See Coastal Waters- Table 2-3 San Marcos Crook 4.52 +101 1 1 . unnamed intermittent streams • 4.53 +1 10 1 - - -11 1 19 1 0 1 - I s - - San Matcos Creek Watershed Sen Marcos Crack ( 4.51 + 1 • I 1 1 1 0 1-01 Encinitas Creek 4.51 1 LEI - Existing Beneficial Use 1 Watsibodiss are listed multiple timas if they cross hydrologic area or sub was boundaries. 0 Potential Beneficial Use 2 Beneficial use designations apply to all uibuwiss to the iodicalsd waterbody, if not listed separately. -I- Lzcepted From MUN (See Text) gIns 12 bthiiCIbL UbtS 2-27 Sspt.mbor S. 1994 Attachment 3 2.3.3.5 Structural Treatment BMP Selection Procedure Priority projects shall select a single or combination of treatment BMPs from the categories in Table 4 that maximize pollutant removal for the particular pollutant(s) of concern. Determine if the project Would discharge to a Clean Water Act Section 303(d) impaired receiving water. If any receiving waters for the project are impaired, note pollutant(s) receiving water(s) is/are listed for. - If the project is anticipated to generate a pollutant (per Table 2) that the receiving water is listed for, select one or more BMPs from Table 4 that maximize the pollutant removal for that pollutant. Any pollutants the project is expected to generate that are also causing a Clean Water Act section 303(d) impairment of the downstream receiving waters of the project shall be given top priority in selecting treatment BMPs If none of the project's receiving waters are listed as impaired, select one or more BMPs from Table 4 that maximize the removal of the pollutants the project is anticipated to generate. Alternative storm water BMPs not identified in Table 4 may be approved at the discretion of the City Engineer, provided the alternative BMP is as effective in removal of pollutants of concern as other feasible BMPs listed in Table 4. Table 4. Structural Treatment Control BMP Selection Matrix Pollutants of BIetention Settling Wet Ponds InflftratIon Facilities or Media High-rate High-rate Trash Racks & Hydro Concern Facilities (LID) Basins (Dry Ponds) and Wetlands Practices Filters biofilters media fitters -dynamic (LID) Devices Coarse Sediment High High High High High High High High and Trash Pollutants that tend to associate with fine particles High High High High High Medium Medium Low during treatment Pollutants that tend to be dissolved Medium Low Medium High Low Low Low Low following treatment 2.3.3.6 Notes on Treatment Control BMP Categories All rankings are relative. Ranking of all facilities assumes proper sizing, design, and periodic maintenance. Following are general descriptions of each category. Bloretentlon Facilities (infiltration planters, flow-through planters, bioretention areas, and bioretention swales). Facilities are designed to capture runoff and infiltrate slowly through soil media which also supports vegetation. Bioretention facilities, except for flow-through planters, effectively promote infiltration into native soils. In day soils, facilities may capture excess treated runoff in an underdrain piped to the municipal storm drain system. Typical criteria: an infiltration surface area at least 4% of tributary impervious area, 6-inch average depth of top reservoir, 18- inch soil layer, 12-inch to 18-inch gravel subsurface storage layer. Settling Basins and Wetlands (extended detention basins, "wet" basins, decorative or recreational lakes or water features also used for stormwater treatment, constructed wetlands). Facilities are designed to capture a minimum water quality volume of 80% of total runoff and detain for a minimum of 48 hours. Some wetland designs have proven effective in removing nutrients, but performance varies. Infiltration Facilities or Practices (infiltration basins, infiltration trenches, dry wells, dispersal of runoff to landscape, pervious pavements). These facilities and landscape designs capture, retain, and infiltrate a minimum of 80% of runoff into the ground. Infiltration facilities are generally only feasible in permeable (Hydrologic Soil Group A or B) soils. Volume and area of infiltration facilities depends on soil permeability and safety factor used. Typical criteria: Infiltration facilities should have pretreatment to remove silt to prolong life of the facility. A 10-foot vertical separation from average seasonal groundwater depth is required. Dispersal to landscape may be accomplished in 15 March 2008 Attachment 7 1?VUflh1? 'fY' 1' 1. 1 1 1t. 1. 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I ---- "I I / X / — I ; / I I I / I I/ ..., , :. , "Ill.. / I . \ ~ \ - \ I \ \ \ — / / / / / 7 ____________N I / I I; // REWS/ON /7 DECEMBER 10. 2007 I DIREC1/ON a FLOW ______ \ \ ' I ' "i' / 1' / \ / 1' " / 11 $ / I I I ' / I I REWS/ON /2 MAY 4, 2007 a \ a \ '\ / I / / / 1 / I / I / / J / REIISION NOL'IAIBER Z 2006 a a — \ \ "\ ( I \ \ ' ' N \ ) /$ $ I I I / : , PRL7'AR AUGUST 1, 2005 \i 11 3UBD/WSION BWNDARY \\ \ 10 \\\\ \\\ \ \ \ \\ \\\\ \ a / 7T' 71/ I i i I a a EXIS11NC ELEVA 11/ /' x, —0 N \ \ \\\ \\ \ \\\ \ // 11 , / I $ I ,,r I%W4 SCALE: 1 \ \ 5' 2' 1 \ \ I \ \" \ . I . s I . : I I . I 1 2710 Laker Avenue West Ci, Suite 100 Pl I = IV Carlsbad, California 92010 Pr 760-931-7700 SL ©2007 O'Day Consultants, Inc. Fax:760-931-8680 G:\051139\0539ex—proposed.dwq Apr 09, 2008 10:24om Xrefs: 0539TP; 0539S1TE; 039GRD; 0539MAP; 0539STR; 05390TL Attachment 8 Section 3 Site and Facility Design for Water Oualitv Protection 3.1 Introduction Site and facility design for stormwater quality protection employs a multi-level strategy. The strategy consists of: i) reducing or eliminating post-project runoff; 2) controlling sources of pollutants; and 3), if still needed after deploying 1) and 2), treating contaminated stormwater runoff before discharging it to the storm drain system or to receiving waters. This section describes how elements i), 2), and 3) of the strategy can be incorporated into the site and facility planning and design process, and by doing so, eliminating or reducing the amount of stormwater runoff that may require treatment at the point where stormwater runoff ultimately leaves the site. Elements i) and 2) may be referred to as "source controls" because they emphasize reducing or eliminating pollutants in stormwater runoff at their source through runoff reduction and by keeping pollutants and stormwater segregated. Section 4 provides detailed descriptions of the BMPs related to elements 1) and 2) of the strategy. Element 3) of the strategy is referred to as "treatment control" because it utilizes treatment mechanisms to remove pollutants that have entered stormwater runoff. Section 5 provides detailed descriptions of BMPs related to element 3) of the strategy. Treatment controls integrated into and throughout the site usually provide enhanced benefits over the same or similar controls deployed only at the "end of the pipe" where runoff leaves the project site. 3.2 Integration of BMPs into Common Site Features Many common site features can achieve stormwater management goals by incorporating one or more basic elements, either alone or in combination, depending on site and other conditions. The basic elements include infiltration, retention/detention, biofilters, and structural controls. This section first describes these basic elements, and then describes how these elements can be incorporated into common site features. Infiltration Infiltration is the process where water enters the ground and moves downward through the unsaturated soil zone. Infiltration is ideal for management and conservation of runoff because it filters pollutants through the soil and restores natural flows to groundwater and downstream water bodies. See Figure 3-1. n#rawrfiow Figure 3-1 Infiltration Basin January 2003 California Stormwater BMP Handbook 3-1 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection The infiltration approach to stormwater management seeks to "preserve and restore the hydrologic cycle." An infiltration stormwater system seeks to infiltrate runoff into the soil by allowing it to flow slowly over permeable surfaces. The slow flow of runoff allows pollutants to settle into the soil where they are naturally mitigated. The reduced volume of runoff that remains takes a long time to reach the outfall, and when it empties into a natural water body or storm sewer, its pollutant load is greatly reduced. Infiltration basins can be either open or closed. Open infiltration basins, include ponds, swales and other landscape features, are usually vegetated to maintain the porosity of the soil structure and to reduce erosion. Closed infiltration basins can be constructed under the land surface with open graded crushed stone, leaving the surface to be used for parking or other uses. Subsurface closed basins are generally more difficult to maintain and more expensive than open filtration systems, and are used primarily where high land costs demand that the land surface be reclaimed for economic use. Infiltration systems are often designed to capture the "first flush" storm event and used in combination with a detention basin to control peak hydraulic flows. They effectively remove suspended solids, particulates, bacteria, organics and soluble metals and nutrients through the vehicle of filtration, absorption and microbial decomposition. Groundwater contamination should be considered as a potential adverse effect and should be considered where shallow groundwater is a source of drinking water. In cases where groundwater sources are deep, there s a very low chance of contamination from normal concentrations of typical urban runoff. tetention and Detention Retention and detention systems differ from infiltration systems primarily in intent. Detention systems are designed to capture and retain runoff temporarily and release it to receiving waters at predevelopment flow rates. Permanent pools of water are not held between storm events. Pollutants settle out and are removed from the water column through physical processes. See Figure 3-2. Retention systems capture runoff and retain it between storms as shown in Figure 3-3. Water held in the system is displaced by the next significant rainfall event. Pollutants settle out and are thereby removed from the water column. Because the water remains in the system for a period of time, retention systems benefit from biological and biochemical removal mechanisms provided by aquatic plants and microorganisms. See Figure 3-3. kd*fridv .. 'I I.:4! Figure 3-2 Simple Detention System 3-2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection Retention/detention systems may release runoff slowly enough to reduce down stream peak flows . l '" andhah to their pre-development levels, allow fine I I ___ >sediments to settle, and uptake dissolved f4J1 miIsi1,u6 nutrients in the runoff where wetland vegetation is included. Bioretention facilities have the added benefit of aesthetic appeal. These systems can be placed in parking lot islands, landscaped areas surrounding buildings, perimeter parking lots and other open space sections. Placing bioretention facilities on land that city regulations require developers to devote to open space efficiently uses the land. An experienced landscape architect can choose plant Figure 3-3 species and planting materials that are easy to Retention System maintain, aesthetically pleasing, and capable of effectively reducing pollutants in runoff from the site. Constructed wetland systems retain and release stormwater in a manner that is similar to retention or detention basins. The design mimics natural ecological functions and uses wetland vegetation to filter pollutants. The system needs a permanent water source to function properly and must be engineered to remove coarse sediment, especially construction related sediments, from entering the pond. Stormwater has the potential to negatively affect natural wetland functions and constructed wetlands can be used to buffer sensitive resources. Biofilters Biofilters, also known as vegetated swales and filter strips, are vegetated slopes and channels designed and maintained to transport shallow depths of runoff slowly over vegetation. Biofilters are effective if flows are slow and depths are shallow (3% slope max.). The slow movement of runoff through the vegetation provides an opportunity for sediments and particulates to be filtered and degraded through biological activity. In most soils, the biofilter also provides an opportunity for stormwater infiltration, which further removes pollutants and reduces runoff volumes. See Figure 3-4. Figure 3-4 Vegetated Swale Swales intercept both sheet and concentrated flows and convey these flows in a concentrated, vegetation-lined channel. Grass filter strips intercept sheet runoff from the impervious network of streets, parking lots and rooftops and divert stormwaters to a uniformly graded meadow, buffer zone, or small forest. Typically the vegetated swale and grass strip planting palette can January 2003 California Stormwater BMP Handbook 3-3 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection comprise a wide range of possibilities from dense vegetation to turf grass. Grass strips and vegetated swales can function as pretreatment systems for water entering bioretention systems or other BMPs. If biofilters are to succeed in filtering pollutants from the water column, the planting design must consider the hydrology, soils, and maintenance requirements of the site. Appropriate plantings not only improve water quality, they provide habitat andaesthetic benefits. Selected plant materials must be able to adapt to variable moisture regimes. Turf grass is acceptable if it can be watered in the dry season, and if it is not inundated for long periods. Species such as willows, dogwoods, sedge, rush, lilies and bulrush species tolerate varying degrees of soil moisture and can provide an attractive plant palette year round. Structural Controls Structural controls in the context of this section include a range of measures that prevent pollutants from coming into contact with stormwater. In this context, these measures may be referred to as "structural source controls" meaning that they utilize structural features to prevent pollutant sources and stormwater from coming into contact with one another, thus reducing the opportunity for stormwater to become contaminated. Examples of structural source controls include covers, impermeable surfaces, secondary containment facilities, runoff diversion berms, and diversions to wastewater treatment plants. 3.2.1 Streets More than any other single element, street design has a powerful impact on stormwater quality. 3treet and other transportation related structures typically can comprise between 60 and 70% of the total impervious coverage in urban areas and, unlike rooftops, streets are almost always directly connected to an underground stormwater system. Recognizing that street design can be the greatest factor in development's impact on stormwater quality, it is important that designers, municipalities and developers employ street standards that reduce impervious land coverage. Directing runoff to biofilters or swales rather than underground storm drains produces a street system that conveys stormwater efficiently while providing both water quality and aesthetic benefits. On streets where a more urban character is desired, or where a rigid pavement edge is required, curb and gutter systems can be designed to empty into drainage swales. These swales can run parallel to the street, in the parkway between the curb and the sidewalk, or can intersect the street at cross angles, and run between residences, depending on topography or site planning. Runoff travels along the gutter, but instead of being emptied into a catch basin and underground pipe, multiple openings in the curb direct runoff into surface swales or infiltration/detention basins. In recent years new street standards have been gaining acceptance that meets the access requirements of local residential streets while reducing impervious land coverage. These standards create a new class of street that is narrower and more interconnected than the current ocal street standard, called an "access" street. An access street is at the lowest end of the street ilerarchy and is intended only to provide access to a limited number of residences. 3-4 - -- California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection Street design is usually mandated by local municipal standards. Officials must consider the scale of the land use as they select stormwater and water quality design solutions. Traffic volume and speeds, bicycle lane design criteria, and residential and business densities influence the willingness of decision makers to permit the narrow streets that include curbiess design alternatives. - Emergency service providers often raise objections to reduced street widths. Street designs illustrated here meet national Fire Code standards for emergency access. An interconnected grid system of narrow streets also allows emergency service providers with multiple access routes to compensate for the unlikely possibility that a street may be blocked. Many municipal street standards mandate 8o to i00% impervious land coverage in the public right-of-way, and are a principal contributor to the environmental degradation caused by development. A street standard that allows an interconnected system of narrow access streets for residential neighborhoods has the potential to achieve several complimentary environmental and social benefits. A hierarchy of streets sized according to average daily traffic volumes yields a wide variety of benefits: improved safety from lower speeds and volumes, improved aesthetics from street trees and green parkways, reduced impervious land coverage, less heat island effect, and lower development costs. If the reduction in street width is accompanied by a drainage system that allows for infiltration of runoff, the impact of streets on stormwater quality can be greatly mitigated. There are many examples of narrow streets, from both newly constructed and older communities, which demonstrate the impact of street design on neighborhood character and environmental quality. See Table 3-1. Table 3-1 Adopted Narrow Street Standards (Typ. Cross-Sections, two-way traffic) City of Santa Rosa 30 ft wide with parking permitted both sides, <1000 Average Daily Traffic (ADT) 26-28 ft with parking permitted one side 20 ft - no parking permitted 20 ft neck downs at intersections City of Palmdale 28 ft wide with parking permitted both sides City of San Jose 30 ft wide with parking permitted both sides, <21 Dwelling Units (DU) 34 ft wide with parking permitted both sides, <121 DU City of Novato 24 ft wide with parking permitted both sides, 2-4 DU 28 ft with parking permitted both sides, 5-1.5 DU County of San Mateo '9 ft wide rural pavement cross-section with parking permitted on adjacent gravel shoulders A comparison of street cross-sections is shown in Figure 3-5. January 2003 California Stormwater BMP Handbook 3-5 New Development and Redevelopment www.cabmphandbooks.com OPNEN11ONAL upw nrflt paitdng boll Ides ndnip (ncomrele getter Idsk both Ides nomstlr.sa 83% sr.bue lend coverage RURAL Is, pemu,d MMV on — dMON ftmw in gmvol WMW 10 da - mred maci 32% Ine,vbua land coverage IETRADT1GIPL W pimaid m-00 paift both On rOisgs In comb SdtV wrmkkadw lsqu,sV=drffdMdMMB 3% beMaue lend coverage Section 3 Site and Facility Design for Water Quality Protection Figure 3-5 Comparison of Street Cross-Sections (two-way traffic, residential access streets) 3.2.2 Parking Lots In any development, storage space for stationary vehicles can consume many acres of land area, often greater than the area covered by streets or rooftops. In a neighborhood of single-family homes, this parking area is generally located on private driveways or along the street. In higher density residential developments, parking is often consolidated in parking lots. The space for storage of the automobile, the standard parking stall, occupies only 160 ft2, but when combined with aisles, driveways, curbs, overhang space, and median islands, a parking lot can require up to 400 ft2 per vehicle, or nearly one acre per 100 cars. Since parking is usually accommodated on an asphalt or concrete surface with conventional underground storm drain systems, parking lots typically generate a great deal of DCIA. 3-6 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com 'Jndeuiasg lvd I Section 3 Site and Facility Design for Water Quality Protection There are many ways to both reduce the impervious land coverage of parking areas and to filter runoff before it reaches the storm drain system. Hybrid Parking Lot Hybridlots work on the principle that pavement use differs between aisles and stalls. Aisles must be designed for speeds between 10 and 20 mph, and durable enough to support the concentrated traffic of all vehicles using the lot. The stalls, on the other hand, need only be designed for the 2 or 3 mph speed of vehicles maneuvering into place. Most of the time the stalls are in use, vehicles are stationary. Hybrid lots reduce impervious surface coverage in parking areas by differentiating the paving.between aisles and stalls, and combining impervious aisles with permeable stalls, as shown in Figure 3-6. Impviows aisle pesiutable stalfr Figure 3-6 Hybrid Parking Lot If aisles are constructed of a more conventional, impermeable material suitable for heavier ( vehide use, such as asphalt, stalls can be constructed of permeable pavement. This can reduce the overall impervious surface coverage of a typical double loaded parking lot by 60% and avoid the need for an underground drainage system. Permeable stalls can be constructed of a number of materials including pervious concrete, unit• payers such as brick or stone spaced to expose a permeable joint and set on a permeable base, crushed aggregate, porous asphalt, turf block, and cobbles in low traffic areas. Turf blocks and permeable joints are shown in Figures 3-7 and 3-8. Figure 3-7 Turf Blocks AWWWOUM #mmbkj@iw man" a •• lb I a I ..' , :.• S. a.sitds.uing&d j'<P 5 kw MIMW • Figure 3-8 Permeable Joints January 2003 California Stormwater BMP Handbook 3-7 New Development and Redevelopment www.cabmphandbooks.com Figure 3-11 Overflows Parking Section 3 Site and Facility Design foe Water Quality Protection Parking Grove A variation on the permeable stall design, a grid of trees and bollards can be used to delineate parking stalls and create a "parking grove." If the bollard and tree grids are spaced approximately 19 ft apart, two vehicles can park between each row of the grid. This 9.5 ft stall spacing is slightly more generous that the standard 8.5 to 9 ft stall, and allows for the added width of the tree trucks and bollards. A benefit of this design is that the parking grove not only shades parked cars, but also presents an attractive open space when cars are absent. Examples of parking groves are shown in Figures 3-9 and 3-10. Figure 3-9 Figure 3-10 Parking Grove Parking Grove Overflow Parking Parking lot design often is required to accommodated peak demand, generating a high proportion of impervious land coverage of very limited usefulness. An alternative is to differentiate between regular and peak parking demands, and to construct the peak parking stalls of a different, more permeable, material. This "overflow parking" area can be made of a turf block, which appears as a green lawn when not occupied by vehicles or crushed stone or other materials. See Figure 3-11. The same concept can be applied to - areas with temporary parking needs, such as emergency access routes, or in residential applications, RV, or trailer parking. 49lstvsi.a/Ietensioa 3-8 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com a- Section 3 Site and Facility Design for Water Quality Protection Porous Pavement Recharge Bed In some cases, parking lots can be designed to perform more complex stormwater management functions. Constructing a stone-filled reservoir below the pavement surface and directing runoff underground by means of perforated distribution pipes can achieve subsurface stormwater storage and infiltration as shown in Figure 3-12. Subsurface infiltration basins eliminate the possibilities of mud, mosquitoes and safety hazards sometimes perceived to be associated with ephemeral surface drainage. They also can provide for storage of large volumes of runoff, and can be incorporated with roof runoff collection systems. Figure 3-12 Porous Pavement Recharge Bed 3.2.3 Driveways Driveways can comprise up to 40% of the total transportation network in a conventional development, with streets, turn-arounds, and sidewalks comprising the remaining 60%. Driveway length is generally determined by garage setback requirements, and width is usually mandated by municipal codes and ordinances. If garages are setback from the street, long driveways are required, unless a rear alley system is included to provide garage access. If parking for two vehicles side by side is required, a 20 ft minimum width is required. Thus, if a 20 ft setback and a two car wide driveway are required, a minimum of 400 ft2 of driveway will result, or 4% of a typical 10,000 ft2 residential lot. If the house itself is compact, and the driveway is long wide, and paved with an impervious material such as asphalt or concrete, it can become the largest component of impervious land coverage on the lot. Municipalities can reduce the area dedicated to driveways by allowing for tandem parking (one vehicle in front of another on a narrow driveway). Also, if shared driveways are permitted, then two or more garages can be accessed by a single driveway,, further reducing required land area. Rear alley access to the garage can reduce driveway length, but overall impervious surface coverage may not be reduced if the alleys are paved with impervious materials and the access streets remain designed to conventional municipal standards. Alternative solutions that work to reduce the impact of water quality problems associated with impervious land coverage on city streets also work on driveways. Sloping the driveway so that it drains onto an adjacent turf or groundcover area prevents driveways from draining directly to storm drain systems. This concept is shown in Figures 3-13 and 3-14. Use of turf-block or unit payers on sand creates attractive, low maintenance, permeable driveways that filter stormwater. See Figure 3-15. Crushed aggregate can serve as a relatively smooth pavement with minimal maintenance as shown in Figure 3-16. Paving only under wheels (Figure 3-17) is a viable, inexpensive design if the driveway is straight between the garage and the street and repaving temporary parking areas with permeable unit payers such as brick or stone can significantly reduce the percentage of impervious area devoted to the driveway. January 2003 California Stormwater BMP Handbook 3-9 New Development and Redevelopment www.cabmphandbooks.com YfJluw ISPWI Section 3 Site and Facility Design for Water Qualify Protection fiermuafff snfthvr.:vv 1iuosi! .. AwflM to I 1 Figure 3-14 Alternative Solution Slopes Flow, to Groundcover Figure 3-13 Traditional Design Drains Flow Directly to Storm Drain ._;a Figure 3-15 Unit Payers Figure 3-16 Crushed Aggregate .L _J... ..L..L Figure 3-17 Paving Only Under Wheels 310 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection 3.2.4 Landscape and Open Space In the natural landscape, most soils infiltrate a high percentage of rainwater through a complex web of organic and biological activities that build soil porosity and permeability. Roots reach into the-soil and separate particles of clay, insects excavate voids in the soil mass, roots decay leaving networks of macro pores, leaves fall and form a mulch over the soil surface, and earthworms burrow and ingest organic detritus to create richer, more porous soil. These are just a few examples of the natural processes that occur within the soil. Maintenance of a healthy soil structure through the practice of retaining or restoring native soils where possible and using soil amendments where appropriate can improve the land's ability to filter and slowly release stormwater into drainage networks. Construction practices such as decreasing soil compaction, storing topsoil on-site for use after construction and chipping wood for mulch as it is cleared for the land can improve soil quality and help maintain healthy watersheds. Practices that reduce erosion and help retain water on-site include incorporating organic amendments into disturbed soils after construction, retaining native vegetation, and covering soil during revegetation. Subtle changes in grading can also improve infiltration. Landscape surfaces are conventionally graded to have a slight convex slope. This causes water to run off a central high point into a surrounding drainage system, creating increased runoff. if a landscape surface is graded to have a slightly concave slope, it will hold water. The infiltration value of concave vegetated surfaces is greater in permeable soils. Soils of heavy clay or underlain with hardpan provide less infiltration value. In these cases concave vegetated surfaces must be designed as retention/detention basins, with proper outlets or under drains to an interconnected system. Multiple Small Basins Biofilters, infiltration, retention/detention basins are the basic elements of a landscape designed for stormwater management. The challenge for designers is to integrate these elements creatively and attractively in the landscape - either within a conventional landscape aesthetic or by presenting a different landscape image that emphasizes the role of water and drainage. Multiple small basins can provide a great deal of water storage and infiltration capacity. These small basins can fit into the parkway planting strip or shoulders of street rights-of-way. If connected by culverts under walks and driveways, they can create a continuous linear infiltration system. Infiltration and retention/detention basins can be placed under wood decks, in parking lot planter islands, and at roof downspouts. Outdoor patios or seating areas can be sunken a few steps, paved with a permeable pavement such as flagstone or gravel, and designed to hold a few inches of water collected from surrounding rooftops or paved areas for a few hours after a rain. All of these are examples of small basins that can store water for a brief period, allowing it to infiltrate into the soil, slowing its release into the drainage network, and filtering pollutants. An ordinary lawn can be designed to hold a few inches of water for a few hours after a storm, attracting birds and creating a landscape of diversity. Grass/ vegetated swales can be integrated with landscaping, providing an attractive, low maintenance, linear biofliter. Extended detention (dry ponds) store water during storms, holding runoff to predevelopment levels. Pollutants January 2003 CalifornIa Stomiwater BlIP Handbook 3-11 New Development and Redevelopment www.cabmphandbooks.com - - Section 3 Site and Facility Design for Water Quality Protection settle and are removed from the water column before discharging to streams. Wet ponds serve a similar purpose and can increase property values by providing a significant aesthetic, and passive recreation opportunity. Plant species selection is critical for proper functioning of infiltration areas.- Proper selection of plant materials can improve the infiltration potential of landscape areas. Deep-rooted plants help to build soil porosity. Plant leaf-surface area helps to collect rainwater before it lands on the soil, especially in light rains, increasing the overall water-holding potential of the landscape. A large number of plant species will survive moist soils or periodic inundation . T h e s e plants provide a wide range of choices for planted infiltration/detention basins and drainage swales. Most inundated plants have a higher survival potential on well-drained alluvial soils than on fine textured shallow soils or clays. Maintenance Needs for Stormwater Systems All landscape treatments require maintenance. Landscapes designed to perform stormwater management functions are not necessarily more maintenance intensive than highly manicured conventional landscapes. A concave lawn requires the same mowing, fertilizing and weeding as a convex one and often less irrigation because more rain is filtered into the underlying soil. Sometimes infiltration basins may require a different kind of maintenance than conventionally practiced. Typical maintenance activities include periodic inspection of surface drainage systems to ensure clear flow lines, repair of eroded surfaces, adjustment or repair of drainage structures, soil cultivation or aeration, care of plant materials, replacement of dead plants, replenishment of mulch cover, irrigation, fertilizing, pruning and mowing. Also, dead or stressed vegetation may indicate chemical dumping. Careful observation should be made of these areas to determine if such a problem exists. Landscape maintenance can have a significant impact on soil permeability and its ability to support plant growth. Most plants concentrate the majority of their small absorbing roots in the upper 6 in. of the soil surface if a mulch or forest litter protects the surface. If the soil is exposed or bare, it can become so hot that surface roots will not grow in the upper 8 to ioin. The common practice of removing all leaf litter and detritus with leaf blowers creates a hard-crusted soil surface of low permeability and high heat conduction. Proper mulching of the soil surface improves water retention and infiltration, while protecting the surface root zone from temperature extremes. In addition to impacting permeability, landscape maintenance practices can have adverse effects on water quality. Because commonly used fertilizers and herbicides are a source of organic compounds, it is important to keep these practices to a minimum, and prevent over watering. When well maintained and designed, landscaped concave surfaces, infiltration basins, swales and bioretention areas can add aesthetic value while providing the framework for nvironmentally sound, comprehensive stormwater management systems. 3-12 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection Street Trees Trees improve water quality by intercepting and storing rainfall on leaves and branch surfaces, thereby reducing runoff volumes and delaying the onset of peak flows. A single street tree can have a total leaf surface area of several hundred to several thousand ft2, depending On species and size. This aboveground surface area created by trees and other plants greatly contributes to the water holding capacity of the land. They attenuate conveyance by increasing the soil's capacity to filter rainwater and reduce overland flow rates. By diminishing the impact of raindrops on unvegetated soil, trees reduce soil erosion. Street trees also have the ability to reduce ambient temperature of stormwater runoff and absorb surface water pollutants. When using street trees to achieve stormwater management goals, it is important to use tree species with wide canopies. Street tree design criteria should specify species expected to attain 20 to 30 ft canopies at maturity. Planter strips with adequate width and depth of soil volume are necessary to ensure tree vitality and reduce future maintenance. Structural soils also provide rooting space for large trees and can be specified along narrow planter s t r i p s a n d underneath sidewalks to enable continuous belowground soil and root connections. 3.2.5 Outdoor Work AreaS The site design and landscape details listed in previous sections are appropriate for uses whe r e low concentrations of pollutants can be mitigated through infiltration, retention and detention. Often in commercial and industrial sites, there are outdoor work areas in which a higher ( concentration of pollutants exists, and thus a higher potential of pollutants infiltrating the soil. These work areas often involve automobiles, equipment machinery, or other commercial and industrial uses, and require special consideration. Outdoor work areas are usually isolated elements in a larger development. Infiltration and detention strategies are still appropriate for and can be applied to other areas of the site, such as parking lots, landscape areas, employee use areas, and bicycle path. It is only the outdoor work area within the development - such as the loading dock, fueling area, or equipment wash area - that requires a different drainage approach. This drainage approach is often precisely the opposite from the infiltration/detention strategy - in other words, collect and convey. In these outdoor work areas, infiltration is discouraged and runoff is often routed directly to the sanitary sewer, not the storm drain. Because this runoff is being added to the loads normally received by the water treatment plants (publicly owned treatment works - POTWs), it raises several concerns that must be addressed in the planning and design stage. These include: Higher flows that could exceed the sewer system capacity Catastrophic spills that may cause harm to POTW operation A potential increase in pollutants These concerns can be addressed at policy, management, and site planning levels. January 2003 California Stormwatar BMP Handbook 3-13 New Development and Redevelopment www.cabmphandbookc rm Section 3 Site and Facility Design for Water Quality Protection Policy Piping runoff and process water from outdoor work areas directly to the sanitary sewer for treatment by a downstream POTW displaces the problem of reducing stormwater pollution. Municipal stormwater programs and/or private developers can work with the local POTW to develop solutions that minimize effects on the treatment facility. It should be noted that many POTWs have traditionally prohibited the discharge of stormwater to their systems. However, these prohibitions are being reviewed in light of the benefits possible from such diversions. Management Commercial and industrial sites that host special activities need to implement a pollution prevention program minimizing hazardous material use and waste. For example, if restaurant grease traps are directly connected to the sanitary sewer, proper management programs can mitigate the amount of grease that escapes from the trap, clogging sewer systems and causing overflows or damage to downstream systems. Site Planning Outdoor work areas can be designed in particular ways to reduce their impacts on both stormwater quality and sewage treatment plants. Create an impermeable surface such as concrete or asphalt, or a prefabricated metal drip pan, depending on the use. Cover the area with a roof. This prevents rain from falling on the work area and becoming polluted runoff. Berm or mound around the perimeter of the area to prevent water from adjacent areas to flow on to the surface of the work area. Directly connect runoff. Unlike other areas, runoff from these work areas is directly connected to the sanitary sewer or other specialized containment systems. This allows the more highly concentrated pollutants from these areas to receive special treatment that removes particular constituents. Approval for this connection must be obtained from the appropriate sanitary sewer agency. Locate the work area away from storm drains or catch basins. If the work area is adjacent to, or directly upstream from a storm drain or landscape drainage feature (e.g., bioswales), debris or liquids from the work area can migrate into the stormwater system. Plan the work area to prevent run-on. This can be accomplished by raising the work area or by diverting run-on around the work area. These design elements are general considerations for work areas. In designing any outdoor work area, evaluate local ordinances affecting the type of work area, as many local jurisdictions have specific requirements. Some activities are common to many commercial and industrial sites. These include garbage and recycling, maintenance and storage, and loading. These activities can have a significant 3-14 - -- - CaIItoma Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Water Quality Protection negative impact on stormwater quality, and require special attention to the siting and design of the activity area. 3.2.6 Maintenance and Storage Areas To reduce the possibility of contact with stormwater runoff, maintenance and storage areas can be sited away from drainage paths and waterways, and covered. Implementing a regular maintenance plan for sweeping, litter control, and spill cleanup also helps prevent stormwater pollution. Specifying impermeable surfaces for vehicle and equipment maintenance areas will reduce the chance of pollutant infiltration. A concrete surface will usually last much longer than an asphalt one, as vehicle fluids can either dissolve asphalt or be absorbed by the asphalt and released later. See Figure 3-18. ino Figure 3-18 Material Storage 3.2.7 Vehicle and Equipment Washing Areas It is generally advisable to cover areas used for regular washing of vehicles, trucks, or equipment, surround them with a perimeter berm, and clearly mark them as a designated washing area. Sumps or drain lines can be installed to collect wash water, which may be treated for reuse or recycling, or for discharge to the sanitary sewer. The POTW may require some for m of pretreatment, such as a trap, for these areas. Fueling and maintenance activities must be isolated from the vehicle washing facilities. These activities have specific requirements, described later in this section. Storage of bulk materials, fuels, oils, solvents, other chemicals, and process equipment should be accommodated on an impervious surface covered with a roof. To reduce the chances of corrosion, materials should not be stored directly on the ground, but supported by a wire mesh or other flooring above the impervious pavement. In uncovered areas, drums or other containers can be stored at a slight angle to prevent ponding of rainwater from rusting the lids. Liquid containers should be stored in a designated impervious area that is roofed, fenced within a berm, to prevent spills from flowing into the storm drain. If hazardous materials are being used or stored, additional specific local, state or federal requirements may apply. 3.2.8 Loading Area Loading areas and docks can be designed with a roof or overhang, and a surrounding curb or berm. See Figure 3-19. The area should be graded to direct flow toward an inlet with a shutoff valve or dead-end sump. The sump must be designed with enough capacity to hold a spill while the valve is closed. If the sump has a valve, it must be kept in the closed position and require a n January 2003 California Stormwater BlIP Handbook 3-15 New Development and Redevelopment www.cabmphandbooks.com Section 3 Site and Facility Design for Wafer Quality Protection action to open it. All sumps must have a sealed bottom so they cannot infiltrate wate r . Contaminated accumulated waste and liquid must not be discharged to a storm drain and may be discharged to the sanitary sewer only with the POTW's permission. If the waste is not approved for discharge to the sanitary sewer, it must be conveyed to a hazardous waste (or other offsite disposal) facility, and may require pretreatment. Some specific uses have unique requirements. 3.2.9 Trash Storage Areas Areas designated for trash storage can be covered to protect containers from rainfall. Where covering the trash storage area is not feasible, the area can be protected from run on using grading and berms, and connected to the sanitary sewer to prevent leaks from leaving the designated trash storage area enclosure. 3.2.10 Wash Areas Areas designated for washing of floor mats, containers, exhaust filters, and similar items can be covered and enclosed to protect the area from rainfall and from overspray leaving the area. These areas can also be connected to the sanitary sewer to prevent wash waters from leaving the designated enclosures. A benefit of covering and enclosing these areas is that vectors may be reduced and aesthetics of the area improved. 3.2.11 Fueling Areas In all vehicle and equipment fueling areas, plans must be developed for cleaning near fuel dispensers, emergency spill cleanup, and routine inspections to prevent leaks and ensure properly functioning equipment. If the fueling activities are minor, fueling can be performed in a designated, covered and bermed area that will not allow run-on of stormwater or runoff of spills. Retail gasoline outlets and vehicle fueling areas have specific design guidelines. These are described in a Best Management Practice Guide for retail gasoline outlets developed by the California Stormwater Quality Task Force, in cooperation with major gasoline corporations. The practice guide addresses standards for existing, new, or substantially remodeled facilities. In addition, some municipal stormwater permits require RGOs to provide appropriate runoff treatment. Fuel dispensing areas are defined as extending 6.5 ft from the corner of each fuel dispenser or the length at which the hose and nozzle assembly may be operated plus 1 ft, whichever is less. These areas must be paved with smooth impervious surfaces, such a Portland cement concrete, with a 2-4% slope to prevent ponding, and must be covered. The cover must not drain onto the work area. The rest of the site must separate the fuel dispensing area by a grade break that prevents run-on of stormwater. Within the gas station, the outdoor trash receptacle area (garbage and recycling), and the jr/water supply area must be paved and graded to prevent stormwater run-on. Trash receptacles should be covered. 3-16 CalIfornia Stormwater BMP Handbook January 2003 New Development and Redevelopment wWw.cabmphandbooks.com - -- Attachment 9 Nl- (1% Section 4 .. Source Control BMPs 4.1 Introduction This section describes specific source control Best Management Practices (BMPs) to be considered for incorporation into newly developed public and private infrastructure, as well as retrofit into esisting facilities to meet stormwaler merugement objectives. 4.2 BMP Fact Sheets Source control fact sheets for design are listed in Table 4-1. The fact sheets detail planning methods and concepts that sbouldbe taken into consideration by developers during project design. The fact sheets are arranged in three categones those that have to do with landscape, irrigation, and signsge considerations; those that have to do withuse of particular materials; and those that have to do with design of particular areas. 4.3 Fact Sheet Format A BMP fact sheet isa short document that provides information about a particular BMP. Typically, each fact sheet contains the information outlined in Figure 4-1. Supplemental information is provided if it is available. The fact sheets also contain side bar presentations with information on BMP design objectives. Completed fact sheets for each of the above activities are provided in Section 4.4. Table 4-1 Source Control BMPs for Design Design SD-io Site Decign and Lnd.cape Planning SD-ii Reof RunoffControls SD-12 Efficient Irrigation SD-13 Storm Drain System Sign. Material. SD-2o Pervious Pavements SD-21. Alternative Building Materials Area. SD-30 Fueling Areas SD-31 Maintenance Bays and Docks 50-32 Truh Enclosure. SD-33 Vehicle Washing Areas SD-34 Outdoor Material Storage Area. 50-35 Outdoor Work Areas SD-36 Outdoor Processing Areas SDxx Example Fact Sheet Description oftheBMP Approach Suitable Annikatlona Desian Conalderafloni Designing Newlnstallations Redeveloping Existing Installation. Supplemental Information Examples Other Resources 4.4 BMP Fact Sheets Source Control BMP Fact Sheets for design follow. The BMP fact sheets are individuafly page numbered and are suitable for photocopying and inclusion in stnrmwater quality management plans. Fresh copies of the fact sheets can be individually downloaded from the California Stormwater BMP Handbook website at www.cabmphandbooks.com. Figure 4-1 Example Fact Sheet January 2003 CalifornIa Stormwatar BMP Handbook 4-I Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com Design Objectives Mwdnize Infiltration Provide Retention fiff Slow Runoff Mnimze Impervious Land Coverage Prohibit Dumping of Improper Materials Contain Pollutants Collect and Convey Efficient Irrigation SD-12 Description Irrigation water provided to landscaped areas may result in excess irrigation water being conveyed into stormwater drainage systems Approach Project plan designs for development and redevelopment should include application methods of irrigation water that minimize runoff of excess irrigation water into the stormwater conveyance system. Suitable Applications Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) Design Considerations Designing New Installatiwi. The following methods to reduce excessive irrigation runoff should be considered, and incorporated and implemented where determined applicable and feasible by the Permittee: Employ rain-triggered shutoff devices to prevent irrigation after precipitation. Design irrigation systems to each landscape area's specific water requirements. Include design featuring flow reducers or sinitoff valves triggered by a pressure drop to control water loss in the event of broken sprinider heads or lines. Implement landscape plans consistent with County or City water conservation resolutions which may include provision of water sensors, programmable irrigation times (for short cydes), etc. -. ii. January 2003 CIfornIa Stormwater BMP Handbook I of 2 New Development and Redevelopment www.c,mphandbooks. corn SD-12 Efficient Irriaation L. Design timing and application methods of irrigation water to minimize the runoff of excess irrigation water into the storm water drainage system. Group plants with similrn water requirements in order to reduce excess irrigation runoff and promote surface filtration. Choose plants with low irrigation requirements (for example, native or drought tolerant species). Consider design features such as - Using mulches (such as wood chips or bar) in planter areas without ground cover to minimize sediment in runoff - Installing appropriate plant materials for the location, in accordance with amount of sunlight and climate, and use native plant materials where possible and/or as recommended by the landscape architect - Leaving a vegetative barrier along the property boundary and interior watercourses, to act as a pollutant filter, where appropriate and feasible - Choosing plants that minimize or eliminate the use of fertilizer or pesticides to sustain growth Employ other comparable, equally effective methods to reduce irrigation water runoff. 1,devdopingEziatbig Installation. Various jurisdictional sinrmwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment' in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment If the definition applies, the steps outlined under 'designing new installation? above should be followed. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District; and the Incorporated Cities of Orange County, Draft February 2003: Ventura Countywide Technical Guidance Manual for Storinwater Quality Control Measures, July 2002. 2 of 2 California Stormwater BMP Handbook )auary 2003 New Development and Redevelopment www. cabmphanthooks. corn Storm Drain Signage SD-13 Design Objectives Madnize lnfdfrabon - Provide Retention Slow Runoff Mnime lrrperous Lend Coverage Prohibit Dunping of Improper Materials Contain Pollutants Collect and Convey Description Waste materials dumped into storm drain inlets can have severe impacts on receiving and ground waters. Posting notices regarding discharge prohibitions at storm drain inlets can prevent waste dumping. Storm drain signs and stencils are highly visible source controls that are typically placed directly adjacent to storm drain inlets. Approach The stencil or affixed sign contains a bnof statement that prohibits dumping of improper materials into the urban runoff conveyance system. Storm drain messages have become a popular method of alerting the public about the effects of and the prohibitions against waste di-. Suitable Application. Stencils and signs alert the public to the destination of pollutants discharged to the storm drain. Signs are appropriate in residential, commercial, and industrial areas, as well as any other area where contributions or dumping to storm drains is likely. Design Consideration. Storm drain message markers or placards are recommended at all storm drain inlets within the boundary of a development project. The mailer should be placed in clear sight facing toward anyone approaching the inlet from either side. All storm drain inlet locations should be identified on the development site map. Designing New Inatailatioita The following methods should be considered for inclusion in the project design and show on project plans: Provide stenciling or labeling of all storm drain inlets and catch basins, constructed or modified, within the project area with prohibitive language. Examples include "NO DUMPING .i:., . January 2003 California 9tormwat& BMP Handbook 1 of 2 New Development and Redevelopment www.cabmphandbooks.com SD-13 Storm Drain Signage -DRAINS TO OCEAN" and/or other graphical icons to discourage illegal dumping. Post signs with prohibitive language and/or graphical icons, which prohibit illegal dumping atpublic access points along channels and creeks Within the project area. Note - Some local agencies have approved specific signge and/or storm drain message placards for use. Consult local agency stormwater staff to determine specific requirements for placard types and methods of application. RedevelopmgExi.thig Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. If the project meets the definition of "redevelopmenr, then the requirements stated under u designing new installationir above should be included in all project design plans. Additional Information Maintenance Considerations Legibility of markers and signs should be maintained. If required by the agency with jurisdiction over the proj act, the owner/operator or homeowner's association should enter into a maintenance agreement with the agency or record a deed restriclion upon the property title to maintain the legibility of placards or signs. Placement Signage on top of curbs tends to weather and fade. • Signage on face of curbs tends to be worn by contact with vehide tires and sweeper brooms. Supplemental Information Examples Most MS4 programs have storm drain signage programs. Some MS4 programs will provide stencils, or arrange for volunteers to stencil storm drains as part of their outreach program. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works, May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February 14, 2002. Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood Control District, and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 of 2 California Stormwatec BMP Handbook January 2003 New Development and Redevelopment www. cabmphancbooks. corn Pervious Pavements SD-20 Design Objectives Fff Mdrnze hfitration . Provide Retention Ed Slow Runoff Mnime Impervious Land Coverage Prohibit Dumping of Improper Matenals Contain Pollutants Collect and Convey Description Pervious paving is used for light vehicle loading in parking areas. The term describes a system comprising a load-bearing, durable surface together with an underlying layered structure that temporarily stores water prior In infiltration or drainage to a controlled outlet The surface can itself be porous such that water infiltrates across the entire surface of the material (e.g., grass and gravel surfaces, porous concrete and porous asphalt), or can be built up of impermeable blocks separated by spaces andj oints, through which the water can drain. This latter system is termed 'permeable paving. Advantages of pervious pavements is that they reduce runoff volume while providing treatment, and are unobtrusive resulting in a high level of acceptability. Approach Attenuation of flow is provided by the storage within the underlying structure or sub base, together with appropriate flow controls. An underlying geotextile may permit groundwater recharge, thus contributing to the restoration of the natural water cyde. Alternatively, where infiltration is inappropriate (e.g., if the groundwater vulnerability is high, or the soil type is unsuitable), the surface can be constructed above an impermeable membrane. The system offers a valuable solution for drainage of spatially constrained urban areas. Significant attenuation and improvement in water quality can be achieved by permeable pavements, whichever method is used. The surface and subsurface infrastructure can remove both the soluble and fine particulate pollutants that occur within urban runoff. Roof water can be piped into the storage area directly, adding areas from which. the flow can be attenuated. Also, within lined systems, there is the oppoitunity for stored runoff to be piped out for reuse. Suitable Applications Residential, commercial and industrial applications are possible. The use of permeable pavement may be restricted in cold regions, and regions or regions with high wind erosion. There are some specific disadvantages associated with permeable pavement, which are as follows: January 2003 CaIlforna Stormwat& BMP Handbook 1 of 10 New Development and Redevelopment www.cmrnphandbooks.com SD-20 Pervious Pavements Permeable pavement can become clogged if improperly installed or maintained. However, this is countered by the ease with which small areas of paving can be cleaned or replaced when blocked or damaged Their application should be lirnitedto highways with low traffic volume; axle loads and speeds (less than 30 mph limit), car parking areas and other lightly trafficked or non- trafficked areas. Permeable surfaces are currently not considered suitable for adoptable roads due to the risks associated with failure on high speed roads, the safety implications of ponding, and disruption arising from reconstruction. When using un-lined, infiltration systems, there is some risk of C tminiiting groundwater, depending on soil conditions and aquifer susceptibility. However, this risk is likely to be small because the areas drained tend to have inherently low pollutant loadings. The use of permeable pavement is restricted to gentle slopes Porous block paving has a higher risk of abrasion and damage than solid blocks. Design Considerations DeaigitmgNewhatalloZiona If the grade; subsoils, drainage characteristics, and groundwater conditions are suitable, permeable paving maybe substituted for conventional pavement on parking areas, cul de sacs and other areas with light traffic. Slopes should be flat or very gentle. Scottish experience has (1 shown that permeable paving systems can be installed in a wide range of ground conditions, and the flow attenuation performance is excellent even when the systems are lined. The suitability of a perilous system at a particular pavement site will, however, depend on the loading criteria required of the pavement. Where the system is to be used for infiltrating drainage waters into the ground, the vulnerability of local groundwater sources to pollution from the site should be low, and the seasonal high water table should be at least 4 feet below the surface. Ideally, the pervious surface should be horizontal in order to intercept local rainfall at source. On sloping sites, pervious surfaces maybe terraced to accommodate differences in levels. Design Guidelines The design of each layer of the pavement must be determined by the likely traffic loadings and their required operational life. To provide satisfactory performance, the following criteria should be considered: . The subgrade should be able to sustain traffic loading without excessive deformation. The granular capping and sub-base layers should give sufficient load-bearing to provide an adequate construction platform and base for the overlying pavement layers. The pavement materials should not crack of suffer excessive rutting under the influence of traffic. This is controlled by the horizontal tensile stress at the base of these layers. 2 of 10 California Stonnweter B1P Handbook January 2003 New Development and Redevelopment www.cabnlphancbooks.com Pervious Pavements SD-20 There is no current structural design method specifically for pervious pavements Allowances should be considered the following factors in the design and specification of materials: a Pervious pavements use materials with high permeability and void space. All the cun'ent UK pavement design methods are based on the use of conventional materials that are dense and relatively impermeable. The stiffness of the materials must therefore be assessed. Water is present within the construction and can soften and weaken materials, and this must be allowed for. Existing design methods assume full friction between layers. Any geotextiles or geomembranes must be carefully specified to minimize loss of friction between layers. Porous asphalt loses adhesion and becomes brittle as air passes through the voids. Its durability is thfore lower than conventional materials. The single sized grading of materials used means that care should be taken to ensure that loss of finer particles between unbound layers does not occur. Positioning ageotextile near the surface of the pervious construction should enable pollutants to be trapped and retained dose to the surface of the construction. This has both advantages and disadvantages The main disadvantage is that the filtering of sediments and their associated pollutants at this level may hamper percolation of waters and can eventually lead to surface ponding. One advantage is that even if eventual maintenance is required to reinstate infiltration, only a limited amount of the construction needs to be disturbed, since the sub-base below the geotextile is protected. In addition, the pollutant concentration at a high level in the structure allows for its release over time. it is slowly transported in the stormwater to lower levels where chemical and biological processes may be operating to retain or degrade pollutants. The design should ensure that sufficient void space exists for the storage of sediments to limit the period between remedial works. Pervious pavements require a single size grading to give open voids. The choice of materials is therefore a compromise between stiffness, permeability and storage capacity. Because the sub-base and capping will be in contact with water for a large part of the time, the strength and durability of the aggregate paitides when saturated and subjected to wetting and drying should be assessed. A uniformly graded single size material cannot be compacted and is liable to move when construction traffic passes over it This effect can be reduced by the use of angular crushed rock material with a high surface friction. In pollution control terms, these layers represent the site of long term chemical and biological pollutant retention and degradation processes. The construction materials should be selected, in addition to their structural strength propeitie; for their ability to sustain such processes. In general this means that materials should create neutral or slightly alkaline conditions and they should provide favorable sites for colonization by microbial populations. January 2003 CaIlfrnla Stormwater BMP Handbook 3 of 10 New Development and Redevelopment www.ctmphandbooks.com V... SD-20 Pervious Pavements Construction/Inspection Considerations Permeable surfaces can be laid without cross-falls or longitudinal gradients. • The blocks shouldbe lain level They should not be used for storage of site materials unless the surface is well protected from deposition of silt and other spillages. The pavement should be constructed in a single operation, as one of the last items to be built; an a development site Landscape development should be completed before pavement construction to avoid contamination by silt or soil from this source. Surfaces draining to the pavement should be stabilized before construction of the pavement. inappropriate construction equipment should be kept away from the pavement to prevent iliungge to the surface, sub-base or sub-grade. Maintenance Requirements The maintenance requirements of a pervious surface should be reviewed at the time of design and should be dearly specified. Maintenance is required to prevent dogging of the pervious surface. The factors to be considered when defining maintenance requirements must include: Type ofuse Ownership Level of trafficking The local environment and any contributing catchments Studies in the UK have shown satisfactory operation of porous pavement systems without maintenance for over ioyears and recent work by Imbe et al. at 9th ICUD, Portland, 2002 describes systems operating for over 20years without maintenance. However, performance under such regimes could not be guaranteed, Table 1 shows typical recommended maintenance regimes: 4 of 10 CalIfornia Stormwater BMP Hodc January 2003 New Development and Redevelopment www.cabmphandx)oks.com Pervious Pavements SD-20 Table 1 Typical Recommended Maintenance Regime. Activity Schedule i Minimize use of salt or grit for de-icing i Keep landscaped areas well maintained Ongoing i Prevent soil being washed onto pavement i Vacuum clean surface using commercially available sweeping machines at the following times: - End of winter (April) 2/3x Per Year - Mld-summer(July/August) - After Autumn leaf-fall (November) i Inspect outlets Annual If routine cleaning does not restore Infiltration rates, then reconstruction of part of the whole of a pervious surface may be required. is The surface area affected by hydraulic failure should be lifted for Inspection of the internal materials to identify the location and As needed (infrequent) extent of the bloclg& reximum i-o yearn i Surface materials should be lifted and replaced after brush cleaning. Geotextiles may need complete replacement Sub-surface layers may need cleaning and replacing. Removed silts may need to be disposed of as controlled waste. Permeable pavements are up to 25 % cheaper (or at least no more expensive than the traditional forms of pavement construction), when all construction and drainage costs are taken into account (Accepting that the porous asphalt itself is a more expensive surfacing, the extra cost of which is offset by the savings in underground pipework etc.) (Niemczynowicz, etal., 1987) Table 1 gives US cost estimates for capital and maintenance costs of porous pavements (Landphair et al., 2000) Redevelopmg Existing Installations Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment" in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of" redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment. If the definition applies, the steps outlined under "designing new installations" above should be followed. January 2003 CalIfornia Stormwat& OMP Handbook 5 of 10 New Development and Redevelopment www.cmphandbooks.com SD-20 Pervious Pavements Additional Information Cost Considerations Permeable pavements are up to 25 % cheaper (or at least no more expensive than the traditional forms of pavement construction), when all construction and drainage costs are taken into account (Accepting that the porous asphalt itself is a more expensive surfacing, the extra cost of which is offset by the savings in underground pipewoñ etc.) (Niemczynowicz et al, 1987) Table 2 gives US cost estimates for capital and maintenance costs of porous pavements (Landphair et al., 2000) 6 of 10 California Ston'nwer BMP Handbook )anuary 2003 New Development and Redevelopment www.cabmphan±ooks.corn Pervious Pavements Table 2 Enginee ... s Estimate for Porous Pavement ... SV SIDnePII CY CY l'rla 12.00 11,.00 a.:11.1111 11.15 111.00_ 17.00 Bait Wd EA aaoJIO 0 LI-IIIJ..W r-•v� ..... � Cella,« 111111 NH NJ ... li2IIIUD aD.00 MiO.OO Toa1Aaiii!Va1 11 --■- January 2003 e • $ o.s 212 il:11111 711 201 1DI z ... 1 1 5 1 11.IID 2IIO ...... .. 20D 11.,400 0 IO G ..... .... ... ...... ... - Ill - 0 11e.112 1080 az..llllil: , ... IUJD IIOO a12.aa1 1GOI U.IOD - 0 ll,OGI a1.1DD 2 u.t1U11 :s MMG • -.uuo a 11,500 2 m.auu S ....- • -.uuu S 1100 6 1100 5 ••• . 5 $100 5 122$ 2 "50 $ .. ,. U '818 5 ..... Callfomla Sta'mwater BMP Hllndbook New 0evelC4)ment 1r1d Redevel�ent www.cabmphanct>ooks.com ··-· ,.,,-BEST IMAGE POSSIBLE SD-20 --U.D:zll U,IOO U.100 ., .. .... .. 11,eaa 17.GOO $100 11.125 '11,ffl 7 of 10 SD-20 Pervious Pavements Other Resources Abbott C.L. and Comino-Mateos L. 2001. In situ performance monitoring of an infiltration drainage system andfleld testing of current design procedures. Journal CIWEM, 15(3), pp.198- 202. Construction Industiy Research and Information Association (CIRIA). 2002. Source Control using Constructed Pervious Swfrces C582, London, SW1I' 3AIJ. Construction Industry Research and Information Association (CIRIA). 20o0. Sustainable urban drainage systems - design manual/or Scotland and Northern Ireland Report Ci, London, SWiP 3AU. Construction Industry Research and information Association (CIRIA). 2000 C522 Sustainable urban drainage systems - design manual/or England and Wales, London, SWiP 3A11. Construction Lrnhistiy Research and Information Association (CIRIA). RP8 Manual ofgood practicefor the design, construction and maintenance of infiltration drainage systems/or stormwater runoff control and disposal, London, SWiP 3AU. Dierkes C., Kuhlmann L, Kandasamy J. & Angelis G. Pollution Retention Capability and Maintenance of Permeable Pavements. Proc 9th International Conference on Urban Drainage, Portland Oregon, September 2002. Hart P (2002) Permeable Paving as a Stormwater Source Control System. Paper presented at Scottish Hydraulics Study Group 141h Annual seminar, SUDS. 22 March 2002, Glasgow. Kobayashi M., 1999. Stormwater runoff control in Nagoya City. Proc. 8th mt. Conf. on Urban Storm Drainage, Sydney, Australia, pp.825-833. Landphair, H., McFalls, J., Thompson, D., 2000, Design Methods Selection, and Cost Effectiveness of Storinwater Quality Structures, Texas Transportation Institute Research Report 1837-1, College Station, Texas. Legret M, Colandini V, Effects of a porous pavement with reservior strucufre on runoff waier:waier quality and the fate of heavy metals. Laboratoire Central Des Pouts et Cbaussesss Macdonald K. &Jefferies C. Performance Comparison of Porous Paved and Traditional Car Parks. Proc. First National Conference on Sustainable Drainage Systems, Coventry June 2001. Niemczynowicz J, Hogland W, 1987: Test of porous pavements performed in Lund, Sweden, in Topics in Drainage Hydraulics and Hydrology. BC. Yen (Ed.), pub. hit. Assoc. For Hydraulic Research, pp 19-80. PrattC.J. SUSTAINABLE URBAN DRAINAGE - A Review of published material on the performance of various SUDS devices prepared for the UK Environment Agency. Coventry University, UK December2001. PrattC.J., 1995. Infiltration drainage - case studies of UK practice. Project Report 8 of 10 CalIfornia Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphancbooks.com Pervious Pavements SD-20 22,ConfllfldUstryReSearChand Information Association, London, SWiP 3AU; also known as National Rivers Authority R & D Note 485 Pratt C. J., 1990. Permeable Pavements for Stormwater Quality Enhitncement. In: Urban Stormwater Quality RiThirnrement - Source Control, retmflthng and combined sewer technology, Ed. H.C. Tonlo, ASCE, ISBN o862 7594, pp. 131-155 Raimbault G., 1997 French Developments in Reservoir Structures Sustainable water resources I the 2ist century. Malmo Sweden Sthlüter W. & Jefferies C. Monitoring the outflow from a Porous Car Park Proc First National Conference on Sustainable Drainage Systems, Coventry June 2001. Wild, T.C., Jefferies, C., and D'Arcy, LI. SUDS in Scotland - the Scottish SUDS database Report No SR(02)09 Scotland and Northern Ireland Forwn for Environmental Research, Edinburgh. In preparation August 2002. January 2003 Callfbrnla Stormwater BMP Handbook 9 of 10 New Development and Redevelopment www.cmphandbooks. corn .SD-20 Pervious Pavements S ;• ' •• i:;• F C. hsrisáIi -. mom ci rl (a) P.Mcis pmIsis.dfsfMt.nIIIM S • * . :• • : .4 5, '•Pei MWO Iv- 1 Geces ' . Schematics of a Pervious Pavement System 10 of 10 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphan±oolcs. corn Trash Storage Areas SD-32 Description Trash storage areas are areas where a trash receptacle (a) are located for use as a repository for solid wastes. Stonnwater runoff from areas where trash is stored or disposed of can be polluted. In addition, loose trash and debris can be easily transported by water or wind into nearby storm drain inlets) thrninds, and/or creeks. Waste handling operations that may be sources of stormwater pollution include dumpsters, litter control, and waste piles. Approach This fact sheet contains details on the specific measures required to prevent or reduce pollutants in stormwater runoff associated with trash storage and handling. Preventative measures including enclosures containment structures, and impervious pavements to mitigate spills) should be used to reduce the likelihood of contamination. Suitable Application. Design Objectives Mmdrnze Infiltration Provide Retention Slow Runoff Mnime liTpervious Land Coverage Prohibit Dunping of rnproper Materials Ed Contain Pollutants Collect and Convey Appropriate applications include residential, commercial and industrial areas planned for development or redevelopment. (Detached residential single-family homes are typically excluded from this requirement.) Design Consideration. Design requirements for waste handling areas are governed by Building and Fire Codes, and by current local agency ordinances and zoning requirements. The design criteria described in this fact sheet are meant to enhance and be consistent with these code and ordinance requirements. Hazardous waste should be bandied in accordance with legal requirements established in Title 22, California Code of Regulation. Wastes from commercial and industrial sites are typically hauled by either public or commercial carriers that may have design or access requirements for waste storage areas. The design criteria in this fact sheet are recommendations and are not intended in be in conflict with requirements established by the waste hauler. The waste hauler should be contacted prior to the design of your site trash collection areas. Conflicts or issues should be discussed with the local agency. Designing New histallatio,s. Trash storage areas should be designed to consider the following structural or treatment control BMPs: Design trash container areas so that drainage from acoming roofs and pavement is diverted around the area(s) to avoid run-on. This might include berming or grading the waste handling area to prevent run-on of stormwater. Make sure trash container areas are screened or walled to prevent off-site transport of trash. January 2003 Callfbrnla Stormwater SMP Handbook 1 of 2 New Development and Redevelopment www.cthrnphandbooks.com SD-32 Trash Storage Areas . Use lined bins or dumpsters to reduce leaking of liquid waste. Provide roof; awnings, or attathed lids on all trash containers to minimize direct precipitation and prevent rainfall from entering containers. Pave trash storage areas with an impervious surface to mitigate spills. Do not locate storm drains in immediate vicinity of the trash storage area. Post signs on all dumpsters informing users that hazardous materials are not to be disposed of therein Redeveloping Existing In.talluiion. Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.) define "redevelopment' in terms of amounts of additional impervious area, increases in gross floor area and/or exterior construction, and land disturbing activities with structural or impervious surfaces. The definition of " redevelopment" must be consulted to determine whether or not the requirements for new development apply to areas intended for redevelopment If the definition applie; the steps outlined under "designing new installations" above should be followed. Additional Information Mahatexance Con.iderationa (I The integrity of sthictural elements that are subject to damage (i.e., screens, covers, and signs) must be nieinhmedby the owner/operator. Maintenance agreements between the local agency and the owner/operator may be required. Some agencies will require maintenance deed restrictions to be recorded of the property title. If required by the local agency, maintenance agreements or deed restrictions must be executed by the owner/operator before improvement plans are approved. Other Resources A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County Department of Public Works May 2002. Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of San Diego, and Cities in San Diego County, February i, 2002. Model Water Quality Management Plan (WQMP) for County of Orang; Orange County Flood Control District; and the Incorporated Cities of Orange County, Draft February 2003. Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures, July 2002. 2 o 2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphancbooks.com Attachment 10 Section 5 Treatment Control BMPs 5.1 Introduction This section describes treatment control Best Management Practices (BMPs) to be considered for incorporation into newly developed public and private infrasthicture, as well as re t r o f i t i n t o existing facilities to meet stormwater mnngement objectives. BMP f a c t s h e e t s a r e divided into two groups: public domain BMPs and inanufacl]]red (proprietary) BMPs. In some case; the • same BMP may edst in each group for exa m p l e , media filtration. However, treatment BMPs are typicallyvery different between the two groups. Brand names of manufactured BMPs are not stated. Descriptions o f m a n u f a c t u r e d B M P s i n t h i s document should not be inferred as endorsement by the authárs. 5.2 Treatment Control BMPs Public domain and manufactured BMP controls are listed in Table 5-1. Table 5-1 Treatment Control BMP Fubif a Domain Manufactured (Proprietary) Infiltration Infiltration TC-io Infiltration Trench TC-ii Infiltration Basin TC-is Retention/Irrigation Detention and Settling Detention and Settling TC-20 Wet Pond TC-i Constructed Wetland TC-22 Extended Detention Basin MP-20 Wetland Bloflitratlon Blofiltratlon TC-30 Vegetated Swale TC-31 Vegetated Buffer Strip TC-32 Bloretention Filtration Filtration TC-40 Media Filter MP-40 Media Filter Flow Through Separation FtowThrough Separation TC-50 Water Quality Inlet MP-o Wet Vault MP-SL Vortex Separator MP-52 DrainInserts EOther Other Multiple Systems January 2003 CalifornIa Stormwato BMP Handbook 5-1 Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com Section 5 Treatment Contra BMPs 5.3 Fact Sheet Format ABMP fact sheetisa shortdocument that gives A the information about a particular BMP. Typically, each public domain and manufactured BMP fact sheet contains the information outlined in Figure 5-1. The fact sheets also contain side bar presentations with information on BMP design considerations, targeted constituents, and removal effectiveness (if known). Treatment BMP performance, design criteria, and other selection factors are discussed in 54 - 5.6 below. BMP Fact sheets are included in 5.7. TCxx/MPxx Example Fact Sheet Descriplion California Kxperlence Advantigei Limitations Design and Sizing Guidelines Performance Sitlnç Criteria Design Guideline, Maintenance Re1rence. and Sources ofAddltlonallnformatlon Figure 5-1 Example Fact Sheet 5.4 Comparing Performance of Treatment BMPs With a myriad of stormwater treatment BMPs from which in choose, a question commonly asked is "which one is bests'. Particularly when considering a manufactured treatment system, the engineer wants to know if it provides performance that is reasonably comparable to the typical public-domain BMPs like wet ponds or grass swales. With so many BMPs, it is not likely that they perform equally for all pollutants. Thua, the question that each local jurisdiction faces is which treatment BMPs will it allow, and under what circumstances. What level of treatment is desired or reasonable, given the cost? Which BMPs are the most cost-effective? Current municipal stormwater permits specify the volume or rate of stormwater that must be treated, but not the specific level or efficiency of treatment These permits usually require performance to the specific maximum extent practicable (MEP), but this does not translate to an easy to apply specific design criteria. Methodology for comparing BMP performance may need to be expanded to include more than removal effectiveness. Many studies have been conducted on the performance of stormwater treatment BMPs. Several publications have provided summaries of performance (ASCE, 1998; ASCE, 2001; Brown and Schuelei 1997, Shoemaker et al., 2o00; Winter, 2001). These summaries indicate a wide variation in the performance of each type of BMP, making effectiveness comparisons between BMPs problematic. 5.4.1 Variation in Performance There are several reasons for the observed variation. The Variability of Stormwater Quality Stormwater quality is highly variable during a storm, from storm to storm at a site, and between sites even of the same land use. For pollutants of interest; maximum observed concentrations commonly exceed the average concentration by a factor of 100. The average concentration of a storm, known as the event mean concentration (EMC) commonly varies at a site by a factor of S. One aspect of stormwater quality that is highly variable is the particle size distribution (PSD) of 5-2 California Stormwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabrnphandbooks.com Section 5 Treatment Ccntrd BMPs the suspended sediments. This results in variation in the settle ability of these sediments and the pollutants that are attached. For example, several performance studies of manufactured BMPs have been conducted in the upper Midwest and Northeast where deicing sand is commonly used. The sand, washed off dining spring and summer storm; skews the PSD to larger sizes not commonly found in stormwater from California sites except in mountainous areas. Consequently, a lower level efficiency may be observed if the same treatment system is used in California Most Field Studies Monitor Too Few Storms High variability of stormwaler quality requires that a large number of storms be sampled to discern if there is a significant difference in performance among BMPs The small e r t h e a c t u a l difference in performance between BMPs, the greater the number of storms that must be sampled In statistically discern the difference between them. For example, a researcher attempting to determine a difference in performance between two BMPs of io% must monitor many more storms than if the interest is to define the difference within 50%. Given the expense and difficulty, few studies have monitored enough storms to determine the actual p e r f o r m a n c e with a high level of precision. Different Design Criteria Performance of different systems within the same group (e.g., wet ponds) differs significantly in part because of differing design criteria for each system. This in turn can make it problematic to compare different groups of treatment BMPs to each other (e.g, wet ponds to vortex separators). Differing Influent Concentrations and Analytical Variability With most treatment BMPs, efficiency decreases with decreasing influent concentration. This is illustrated in Figure 5-2. Thus, a low removal efficiency may be observed dining a study not because the device is inherently a poorer performer, but possibly because the influent concentrations for the site were unusually low. In addition, as the concentration of a particular constituent such as 'ISS approaches its analytical detection limit; the effect of the variability of the laboratory technique becomes more significant This factor also accounts for the wide variability of observations on the left of Figure 5-2. The variability of the laboratory results as the 1S approaches its analytical detection limit may also account for negative efficiencies at very low influent concentrations (e.g., TSS less than 10 mg/L). However, some negative efficiencies observed at higher concentrations may not necessarily be an artifact of laboratory analysis. The cause varies in some extent with the type of treatment BMP. Negative efficiencies maybe due to the re-suspension of previously deposited pollutants, a change in pH that dissolves precipitated or sorbed pollutants discharge of algae in the case of BMPs with open wet pools, erosion of unprotected basin side or bottom, and the degradation of leaves that entered the system the previous fall. January 2003 CalIfornia Stormwater BMP Handbook 5-3 Errata 9-04 New DeveIcrnent and Redevelopment www. cabmphandbooks. corn Section 5 Treatment Contml BMPs Different Methods of Calculating Efficiency Researchers (1) have used different methods to calculate efficiency, (2) do not always indicate which method they have used, and (3)dten do not provide sufficient information in their report to allow others to recalculate the efficiency using a common method. One approach to quantifying BMP efflciencyisto determine first if the BMP is providing treatment (that the influent and effluent 14 -; - IIS!1 'S - ii. Figure 5-2 Removal EfflciencV Versus Influent Concentration mean event mean concentrations are statistically different from one another) and then examine either a cumulative distribution function of influent and effluent quality or a stnñard parallel probability plot This approach is called the Effluent Probability Method. While this approach has been used in the past by EPA and ASCE, some researchers have experienced problems with the general applicability of this method. A discussion of these issues is included in Appendix B. A second approach to comparing performance among BMPs istn compare effluent concentrations, using a box-whisker plot, the basic form of which is illustrated in Figure The plot represents all of the data points, of one study, several studies, or of individual storms. The plots provide insight into the variability of performance within each BMP type, and possible differences in performance among the types. To explain the plot 50% of the data points as well as the medianvalue of all the data points is represented by the box That is, the median falls within the 75th and 25th percentile of data (top and bottom of the box). The whisker extends in the highest point within a range of 1.5 times the difference between the first and third quartiles. Individual points beyond this range are shown as asterisks. thsNiiMvis of dpaüD thIvMs of Asb&uavUubrmofth.j ThIbOIUIP bdi2M,psi1ssWB. bofU. 7,puriwj716 Ill m#W1m6W&*dftmhm1tpwdhd= afVab Figure 5-3 Box-Whisker Plot 5-4 CalifornIa Stormwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www. abmphdbocks. corn Section 5 Treatment Cczitrci BMPs Recognizing the possible effect of influent concentration an effi c i e n c y , a n a l t e r n a t i v e i s t o compare effluent concentrations. The reasoning is that regardless of the influent concentration, a particular BMP will generate a narrower range of effluent concentrations. Fi g u r e 5-4 shows observed effluent concentrations for several different types of B M P s . T h e s e d a t a w e r e g e n e r a t e d in an extensive field program conducted by the California Department of 1ansportation (Caltrans). As this program is the most extensive effort to date in the entire United States the observations about performance in this Handbook rely heavil y on these data. The Caltrans study is unique in that many of the BMPs were tested under reasonably similar con d i t i o n s (climate, storms, freeway stormwater quality), with each type of BMP s i z e d w i t h t h e s a m e d e s i g n criteria. An additional factor In consider when comparing BMPs is the effect of infiltration. BMPs with concrete or metal structures will have no infiltration, where a s t h e i n f i l t r a t i o n i n e a r t h e n B M P s will vary from none to substantial. For exampl; in the Caltr a n s s t u d y , i n f i l t r a t i o n i n v e g e t a t e d swales averaged nearly o%. This point is illustrated with Figur e 5-4 where effluent quality of several BMPs is compared As seen in Figure 5-4, effluent concentration for grass swales is higher than either filters or wet basins (30 vs. 10 to 15 mg/L), suggesting that swales in comparison are not particularly effective. However, surface w a t e r e n t e r i n g s w a l e s m a y i n f i l t r a t e into the ground, resulting in a loading reduction (flow times co n c e n t r a t i o n ) t h a t i s s i m i l a r t o those BMPs with minimal or no infiltration. 16o- 14O C 120. M 100. 190 a20 - - - . - '----.--- - TC.20 Wet TCZt TC-10 TC-31 TC.40 Media TC-45 Media TC-40 Media Pond Eat ended Vegetated Vegetated FIlter(Austln Filter F liter iM oIl Detention Sls Butter Sand Filter) (Deiam chamber Basin Lineal Sand Tmslinenl Filter) hula) Figure 5-4 Observed Effluent Concentrations for Sever a l D i f f e r e n t P u b l i c D o m a i n B M P s January 2003 CalIfornia Stormwater BMP Handbook 5-5 Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com ___ 40. IL - Section 5 Treatment ODntrd BMPs With equation shown below, it is possible using the data from Figure 5-4 to estimate different levels of loading reduction as a function of the fraction of stormwater that is infiltrated. EEC = (i-I)(EC) + (I)(GC) Where: EEC = the effective effluent concentration I = fraction of stormwater dischaiged by infiltration EC = the median concentration observed in the effluent GC = expected concentration of stormwater when it reaches the groundwater To illustrate the use of the equation above, the effect of infiltration is considered on the effective effluent concentration of 'ISS from swales. From Figure 5-4, the median effluent concentration for swales is about 30 mg/L. Infiltration of 50% is assumed with an expected concentration of 5 mg/L when the stormwater reaches the gmundwater. This gives: EEC = (1-0.5X30) + (o.)() = 17.5 M9/1- The above value can be compared to other BMPs that may directly produce a lower effluent concentration, but do not exhibit infiltration, such as concrete wet vaults. 5.4.2 Other Issues Related to Performance Comparisons A further consideration related to performance comparisons is whether or not the treatment BMP removes dissolved pollutants. Receiving water standards for most metals are based on the dissolved fraction; the form of nitrogen or phosphorus of most concern as a nutrient is the dissolved fraction. The common practice of comparing the performance of BMPs using iSS may not be considered sufficient by local governments and regulatory agencie; as there is not always a strong, consistent relationship between TSS and the pollutants of interest, particularly those identified in the 303d list for specific water bodies in California. These pollutants frequently include metals, nitrogen, nutrients (but often nutrients without specifying nitrogen or phosphorus), indicator bacteria (i.e., feed coliform), pesticides, and trash. Less commonly cited pollutants include sediment; PAM, PCB; and dioxin. With respect to metals, typically, only the general term is used. In some cases, a specific metal is identified. The most commonly listed metals are mercury, copper, lead, selenium, zinc, and nickel. Less frequently listed metals are cadmium, arsenic, silver, chromium, molybdenum, and thallium. Commonly, only the general term "metals" is indicated for a water body without reference to a particular metal. It is desirable to know how each of the treatment BMPs performs with respect to the removal of the above pollutants. Unfortunately, the performance data are non-existent or very limited for many of the cited pollutants, particularly trash, PAHs, PCBs, dioxin, mercury, selenium, and pesticides. Furthermore, the concentrations of these constituents are very low, often below the 5-6 California Stamwetec BMP Handbook January 2003 New Development and Redevelopment 6-rate 9-04 www.cabrnphendbodcs.com Section 5 Treatment Control BMPs detection limit. This prevents the determination of which BMPs are most effective. However, with the exception of trash and possibly dioxin, these pollutants readily sorb to sediments in stormwater, and therefore absent data at this time can be considered to be removed in proportion to the removal of TSS (i.e., sediment) Therefore, in genera1 those treatment systems that are most effective at removing ISS will be most effective at removing pollutants noted above. While there is little data on the removal of trash, those treatment BMPs that include a basin such as a wet pond or vault, or extended detention basin should be similarly effective at removing trash as long as the design incorporates a means of retinig the floating trash in the BMP. Whether or not manufactured products that are configured as a basin (e.g., round vaults or vortex separators) are as effective as public domain BMPs is unknown. However, their ability to retain floating debris may be limited by the fact that many of these products are relatively small and therefore may have limited storage capacity. Only one manufactured BMP is specifically designed In remove floating debris. There are considerable amounts of performance data for zinc copper, and lead, with a less substantial database for nickel, cadmium, and chromium. An exception is high-use freeways where metals in general are at higher concentrations than residential and commercial properties. Lead sorbs easily to the sediments in stormwater, with typically only io% in the dissolved phase. Hence, its removal is generally indirect proportion to the removal of TSS. In contrast; zinc, copper, and cadmium are highly soluble with o% or more in the dissolved phase. Hence, two treatment BMPs may remove iSS at the same level, but if one is capable of removing dissolved metals, it provides better treatment overall for the more soluble metals. 5.4.3 Comparisons of Treatment BMPs for Nitrogen, Zinc, Bacteria, and TSS Presented in Figures 5-5 through 5-8 are comparisons of the effluent concentrations produced by several types of treatment BMPs for nitrogen, 7inc, and fecal coliform, respectively (lSS is represented in Figure 5-4). Graphs for other metals are provided in Appendix C. These data are from the Caltrans study previously cited. Total and the dissolved effluent concentrations are shown for zinc. (Note that while box-whisker plots are used here to compare BMPs, other methodologies, such as effluent cumulative probability distribution plots, are used by others.) January 2003 Callfbrnla Stormwat& BMP Hdbodc 5-7 Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com Section 5 Treatment Contml BMPs While a figure is provided for fecal coliform, it is important to stress that the performance comparisons between BMPs is problematic. Some California BMP studies have shown excellent removal of fecal coliforin through constructed wetlands and other BMPs. However, BMP comparisons are complicated by the fact that several BMPs attract wildlife and pets, thereby elevating bacteria levels. As bacteria sorb to the suspended sediments, a s i g n i f i c a n t f r a c t i o n m a y be removed by settling or filtration. A caulionaiy note regarding 1ufr0gen when comparing nitrogen removal between treatment systems it is best in use the parameter total nitrogen. It. consists of Total Kjelclahl Nitrogen - TKN (organic nitrogen plus ammonia) plus nitrate. Comparig TKN removal rates is misleading in that in some treatment systems the ammonia is changed to nitrate bnt not removed. Ex*mmfition of the performance data of many systems shows that while TKN may decrease dramatically, the nitrate concentration increases correspondingly. Hence, the overall removal of nitrogen is considerably lower than implied from looking only at Ejeldahi Nitrogen. 5.4.4 General Performance of Manufactured BMPs An important question is how the performance of manufactured treatment BMPs compares to those in the public domain, illustrated previously in Figures 5-4 through 54 Figure 5-9 (and Figure 5-loin log format) presents box-whiakr plots of the removal of 'M for the manufactured systems. Data are presented for five general types of manufactured BMPs: wet vaults, drain inserts, constructed wetlands, media filters, and vortex separators. The figures indicate wide ranges in effluent con'entrations, reflecting in part the different products and design criteria within each type. Comparing Figures and suggests that manufactured products may perform as well as the less effective publicdomain BMPs such as swales and extended detention basins (excluding the additional benefits of infiltration with the latter). Manufactured wdlands may perform as well as the most effective public d o m m n BMPs; however, the plot presented in Figure 5-9 for the msrnufactured wetlands represents only five data points. It should be noted that each type of BMP illustrated in Figure 5-9 contains data from more than one product. Performance of particular products within that grouping may not perform as well as even the least effective publicdomiiin BMPs. This observation is implied by the greater spread within some boxes in Figure 5-9, for example, manufactured wet vaults and vortex separators. Product performance within each grouping of manufactured BMPs vary as follows: Filters - TSS effluent concentrations range from 2 to 280 mg/L, with a median value of 29 mg/L Inserts - ISS effluent concentrations range from 4 to 248 mg/L with a median value of 27 mg/L Wetlands - TSS effluent concentrations vary little, and have a median value of 1.2 Ing/L Vaults - TSS effluent concentrations range from 1 to 467 mg/Lb with a median value of 36 mg/L Vortex - 1S effhient concentrations range from 13 to 359 mg/L, with a median value of 32 mg/L 5-10 C&Iranla Stmwater BMP Handbook January 2003 New Development ad Redevelopment Errata 9-04 www. cabrnph3ldbooks. corn Section 5 Treatment Contml BMPs As noted earlier, performance of particular products in a grouping may be due to different design criteria within the group. For example, wet vault products differ with respect to the volume of the permanent wet pool to the design event volume, filter products differ with respect to the type of media. 5.4.5 Technology Certification This Handbook does not endorse proprietary products although many are described. It is left to each community to determine which proprietary products may be used, and under what circumstances. When considering a proprietary product it is strongly advised that the community consider performance data, but only performance data that have been collected following a widely accepted protocol. Protocols have been developed by the American Society of Civil Engineering (ASCE BMP Data Base Program), and by the U.S.Environmental Protection Agency (Environmental Technology Certification Program). The local jurisdiction should ask the manufacturer of the product to submit a report that describes the product and protocol that was followed to produce the performance data. It can be expected that subsequent to the publishing of this Handbook, new public-domain technologies will be proposed (or design criteria for existing technologies will be altered) by development engineers. As with proprietary products, it is advised that new public-domain technologies be considered only if performance data are available and have been collected following a widely accepted protocol. 5.5 BMP Design Criteria for Flow and Volume Many municipal stormwater discharge permits in California contain provisions such as Standard Urban Stormwater Mitigation Plana, Stormwater Quality Urban Impact Mitigation Plans, or Provision C.3 New and Redevelopment Performance Standarda, commonly refelTed to as SUSMPs, SQUIMPs, or C.3 Provisions, respectively. What these and similar provisions have in common is that they require many new development and redevelopment proj ects to capture and then infiltrate or treat runoff from the project site prior to being discharged to storm drains. These provisions include minimum standards for sizing these treatment control BMPs. Sizing standards are prescribed for both volume-based and flow-based BMPs. Akey point to consider when developing, reviewing, or complying with requirements for the sizing of treatment control BMPs for stormwater quality enhancement is that BMPs are most efficient and economical when they target small, frequent storm events that over lime produce more total runoff than the larger, infrequent storms targeted for design of flood control facilities. The reason for this can be seen by examination of Figure 5-11 and Figure 5-12. Figure 5-11 shows the distribution of storm events at San Jose, California where most storms produce less than 0.50 in. of total rainfall. Figure 5-12 shows the distribution of rainfall intensities at San Jose, California, where most storms have intensities of less than 0.25 in/hr. The patterns at San Jose, California are typical of other locations throughout the state. Figures 5-U and 5-12 show that as storm sizes increase, the number of events decrease. Therefore when BMPs are designed for increasingly larger storms (for example, storms up to 1 in. versus storms Of up to 0.5 in.), the BMP size and cost increase dramatically, while the number of additional 5-12 CalIfornia Stormwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabmphandbooks.com Section 5 Treatment Control BMPs treated storm events are small. Table 5-2 shows that doubling the design storm depth from 0.50 in. to 1.00 in only increases the number of events captured by 23%. Similarly, doubling the design rainfall intensity from 0.25 in/hr to o.o in/hr only increases the number of events captured by 7%. 1200 1000 800 0 600 400 200 0 Rain Storm, at San J08., CA 1948-2000 , . . I. I I• • I. q, Storm Depth, Inch.. Figure 5-11 Rain Storms at San Jose, CA 2963 Rain Intensity at San Jose, CA 2000 1948-2000 .2 25001 - 2000 - 9'335 hourly roedgsI 1500 less than 0.10 lnlhr I I are not shown 1000. 5004 207 10 .0 1 01 • I. 10 $ $ RnfalI Intensity, Inches per Hour Figure 5-12 Rain Intensity at San Jose, CA January 2003 CalIfornia Stormwato- BMP Handbook 5-13 Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com Section 5 Treatment Control BMPs Table 5-2 Incremental Design Criteria VS Storms Treated at San Jose, CA Proposed Number of Incremental Incremental BMP Design Target Historical Events Increase in Increase in InRange Design Criteria Storm. Treated Storm Depth 1,067 0.00 to 0.50 in. +100% Storm Depth 0.51 to 1.00 in. 242 Rainf.11lntensity 2,963 0.10 to 0.25 In/hr +i00% +7% Rainfall Intensity 0.26 to 0.50 in/hr 207 ____________________ _______________ Due to economies of scale, doubling the capbire and treatment requirements for a BMP are not likely to double the cost of many BMP; but the incremental cost per event will increase, making increases beyond a certain point generally unattractive. Typically, design criteria for water quality control BMPs are set to coincide with the 'knee of the curve," that is, the point of inflection where the mgnitude of the event increases more rapidly than number of events captured. Figure 5-13 shows that the 'knee of the curve" or point of diminishing returns for San Jose, California is in the range of 0.75 to 1.00 in. of rainfall. In other words, targeting design ( storms larger than this will produce gains at considerable incremental cost. Similar curves can be developed for rainfall intensity and runoff volume. Rain Storms at San Jose, CA s a as aaaa 1400 i 1200 800 . > !UJ 600 400 200 P%? 00 i,' 'b• 'V bi bi 1bf 4;) ASP Storm Depth, Inches Figure 5-13 Rain Storms at San lose, CA 5-14 California Stcwmwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabmphandbooks.com Section 5 Treatment Control BMPs It is important to note that arbitrarily targeting large, infrequent storm events can actually reduce the pollutant removal capabilities of some BMPs. This occurs when outlet structure; detention time; and drain down times are designed to accommodate unusually large volume s and high flows. When BMPs are over-deigned, the more frequent, small storms that produce the most annual runoff pass quickly through the over-sized BMPs and therefore receive inadequate treatment For example, a detention basin might normally be deigned to capture 0.5 in. of runoff and to release that runoff over 48 hrs providing a high level of sediment removal. If the basin were to be oversized to capture 1.0 in. of runoff and to release that runoff over 48 hrs a more common 0.5 inch runoff event entering basin would drain in approximately 24 hrs meaning the smaller, more frequent storm that is responsible for more total runoff would receive less treatment than if the basin were designed for the smaller event. Therefore, effltñent and economical BMP sizing criteria are usually based on design criteria that correspond to the "knee of the curve' or point of diminishing returns. 5.5.1 Volume-Based BMP Design Volume-based BMP design standards apply to BMPs whose primary mode of pollutant removal depends on the volumetric capacity of the BMP. Examples of BMPs in this category include detention basins, retention basins, and infiltration. 1ypicaliy, a volume-based BMP design criteria calls for the capture and infiltration or treatment of a certain percentage of the runoff from the project site, usually in the range of the 75th to 85th percentile average annual runoff volume. The 75th to 85th percentile capture range corresponds to the "knee of the curve" for ( many sites in California for sites whose composite runoff coefficient is in the 0.50 to 0.95 range. The following are examples of volume-based BMP design standards from current municipal stormwater permits. The permits require that volume-based BMPs be designed to capture and then to infiltrate or treat stormwater runoff equal to one of the following; Eighty (8o) percent of the volume of annual runoff determined in accordance with the methodology set forth in Appendix D of the California Storm Water Best Management Practices Handbook (Stormwater Quality Task Force, 1993), using local rainfall data. The maximized stormwater quality capture volume for the area, based on historical rainfall records, determined using the formula and volume capture coefficients set forth in Urban Runoff Quality Management (WEF Mtnis1 of Practice No. 23/ASCE Manual of Practice No. 87, (1998), pages 175-178). The reader is referred to the municipal stormwater program manger for the jurisdiction processing the new development or redevelopment project application to determine the specific requirements applicable to a proposed project. California Stormwater BMP Handbook Approach The volume-based BMP sizing methodology included in the first edition of the Cahfornia Storm Water Best Management Practice Handbook (Storinwater Quality Task Force, 1993) has been included in this second edition of the handbook and is the method recommended for use. January 2003 Callibmla Stormwatar BMP Hdbodc 5-15 Errata 9-04 New DeveIogm,t and Redevelopment www.cabmphandbooks.com Section 5 Treatment Control BMPS The California Stormwater BMPHandbook approach is based on results of a continuous simulation model, the STORM model, developed by the Hydrologic Engineering Center of the U.S. Army Corps of Engineers (COB-HEC i). The StoMei Treatment; Overflow, Runoff Model (STORM) was applied to long-term hourly rainfall data at numerous sites throughout California, with sites selected throughout the state representing a wide range of municipal stormwater permit areas, climatic areas, geography, and topograpl. STORM translates rainfall into runoff, then routes the runoff through detention storage. The volume-based BMP sizing curves resulting from the STORM model provide a range of options for choosing a BMP sizing curve appropriate to sites in most areas of the state. The volume-based BMP swing curves are included in Appendix D. Key model assumptions are also documented in Appendix D. San Jos, (7821)- Santa Clara County, California am 50 50 70 50 50 40 244ir0rrtdmw InolCflGlII0 ,ICcfli:0.50 50 —mIco.h,g= 1.50 as 0.1 0.2 °1nstoruVon?.cnch.f 01 01 10 Figure 5-14 Capture/Treatment Analysis at San Jose, CA The California Stormwater BMP Handbook approach is simple to apply, and relies largely on commonly available information about a project The following steps describe the use of the BMP sizing curves contained in Appendix D. Identify the "BMP Drainage Area" that drains to the proposed BMP. This includes all areas that will contribute runoff to the proposed BMP, including pervious areas, impervious areas, and off-site areas, whether or not they are directly or indirectly connected to the BMP. Calculate the composite runoff coefficient "C" for the area identified in Step 1. Select a capture curve representative of the site and the desired drain down time using Appendix D. Curves are presented for 24-hour and 48-hour draw down times. The 48-hour curve should be used in most areas of California. Use of the 24-hour curve should be limited 5-16 California Stcwmwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cobmphandbooks.com Section 5 Treatment Control BMPs to drainage areas with coarse soils that readily settle and to watersheds where warming may be detrimental to downstream fisheries. Draw down times in excess of 48 hours should be used with caution, as vector breeding can be a problem after water has stood in excess of 7 hours. Determine the applicable requirement for capture of runoff (Capture, % of Runoff). Enter the capture curve selected in Step 3 on the vertical axs at the "Capture, % Runoff' value identified in Step 4. Move horizontally to the right across capture curve until the curve corresponding In the drainage area's composite runoff coficient "Cl determined in Step 2 i intercepted. Interpolation between curves maybe necessary. Move vertically down fr o m this point until the horizontal axis is intercepted. Read the "Unit Basin Storage Volume " along the horizontal axis. If a local requirement for capture of runoff is not specified, enter the vertical aids at the "knee of the curve" for the curve representing composite runoff coefficient 'C." The "knee of the curve" is typically in the range of 75 to 85% capture. Calculate the required capture volume of the BMP by multiplying the "BMP Drainage Area" from Step 1 by the "Unit Basin Storage Volume" from Step 5 to give the BMP volume. Due to the mixed units that result (e.g., ac-in., ac-ft)it is recommended that the resulting volume be converted to cubic feet for use during design. Urban Runoff Quality Management Approach The volume-based BMP sizing methodology described in Urban R unoff Quality Management (WEF Manual of Practice No. 23/ASCE Manual of Practice No. 87, (1998), pages 175-178) has been included in this edition of the handbook as an alternative to the California Stormwater BMP Handbook approach described above. The Urban Runoff Quality Management Appro a c h is suitable for planning level estimates of the size of volume-based BMPs (WEP/ASCE, 1998, page 175). The Urban Runoff Quality Management approach is similar to the California Stormwater BMP Handbook approach in that it is based on the translation of rainfall to runoff. The Urban Runoff Quality Management approach is based on two regression equations. The first regression equation relates rainfall to runoff. The rainfall to runoff regression equation was developed ititg 2 years of data from more than 6o urban watersheds nationwide. The second regression equation relates mean annual runoff-producing rainfall depths to the "Maximized Water Quality Capture Volume" which corresponds to the 'knee of the cumulative probability curve". This second regression was based on analysis of long-term rainfall data from seven rain gages representing dimAtic zones across the country. The Maximized Water Quality Capture Volume corresponds to approximately the 8th percentile runoff event; and ranges from 82 to 88%. The two regression equations that form the Urban Runoff Quality Management approach are as follows: C = o.88i3 - 0.7812 + 0.7741 + 0.04 P. = (a • C) • P6 January 2003 Callfbrnla Stormwater BMP Hwdboc4 5-17 Errata 9-04 New Development and Redevelopment www.cabcnphandbooks.com Section 5 Treatment Control BMPs Where C = runoff coefficient i = watershed imperviousness ratio which is equal to the percent total imperviousness divided by 100 P. = Maximized Detention Volume, in watershed inches a = regression constant a=1.582 and a=1.963 for 24 and 48 hour draw down, respectively P6 = mean annual runoff-producing rainfall depths, in watershed inches, Table s-i. See Appendix D. The Urban Runoff Quality Management Approach is simple to apply. The following steps. describe the use of the approach. i. Identify the "BMP Drainage Area" that drains to the proposed BMP. This includes all areas that will contribute runoff to the proposed BMP, including pervious areas, impervious areas, and off-site areas, whether or not they are directly or indirectly connected to the BMP. Calculate the "Watershed Imperviousness Ratio" (i), which is equal to the percent of total impervious area in the 'BMP Drainage Area" divided byloo. Calculate the "Runoff Coefficieuf' (C) using the following equation: C = 0.858i3 - 0.78z + 0.7741 + 0.04 Determine the "Mean Annual Runoff' (P6) for the "BMP Drainage Area" using Table s-i in Appendix D. Determine the "Regression Constant' (a) for the desired BMP drain down time. Use a=1.582 for 24 bra and a=1.963 for 48 hr draw down. Calculate the "Maximized Detention Volume!' (Po) using the following equation: Po = (a • C) • P6 Calculate the required capture volume of the BMP by multiplying the "BMP Drainage Area" from Step 1 b the "Maximized Detention Volume" from Step 6 to give the BMP volume. Due to the mixed units that result (e.g., ac-in., ac-ft) it is recommended that the resulting volume be converted to ft3 for use dining design. 5.5.2 Flow-Based BMP Design Flow-based BMP design standards apply to BMPs whose primary mode of pollutant removal depends on the rate of flow of runoff through the BMP. Examples of BMPsin this category 5-18 CaIifnIe Sta-mwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabmphandbooks.com Section 5. Treatment Control BMPs include swale; sand filtera screening device; and many proprietary products. Typically, a flow-based BMP design criteria calls for the capture and infiltration or treatment of the flow runoff produced by rain events of a specified magnitude. The following are examples of flow-based BMP design standards from current municipal stormwater permits. The permits require that flow-based BMPs be designed to capture and then to infiltrate or treat stormwater runoff equal to one of the following: . 10% of the so-yr peak flow rate (Factored Flood Flow Approach) The flow of runoff produced by a rain event equal to at least two times the 85th percentile hourly rainfall intensity for the applicable are; based on historical records of hourly rainfall depths (California Stormwater BMP Handbook Approach). The flow of runoff resulting from a rain event equal in at least 0.2 in/hr intensity (Uniform Intensity Approach) The reader is referred to the municipal stormwater program manager for thejurisdiclion processing the new development or redevelopment project application to determine the specific requirements applicable to a proposed project The three typical requirements shown above all have in common a rainfall intensity element. That i; each criteria is based treating a flow of runoff produced by a rain event of specified rainfall intensity. In the first example, the Factored Flood Flow Approach, the design rainfall intensity is a function of the location and lime of concentration of the area discharging to the BMP. The intensity in this case is determined using Intensity.Duration-Frequency curves published by the flood control agency with jurisdiction over the project or available from climatic data centers. This approach is simple to apply when the so-yr peak flow has already been determined for either drainage system design or flood control calculations. In the second example, the California Stormwater BMP Handbook Approach (so called because it is recommended in this handbook), the rainfall intensity is a function of the location of the area discharging to the BMP. The intensity in this case can be determined using the rain intensity cumulative frequency curves developed for this Handbook based on analysis of long- term hourly rainfall data at numerous sites throughout California, with sites selected throughout the state representing a wide range of municipal stormwater permit areas, climatic areas geography, and topography. These rain intensity cumulative frequency curves are included in Appendix D. This approach is recommended as it reflects local conditions throughout the state. The flow-based design criteria in some municipal permits require design based on two limes the 85th percentile hourly rainfall intensity. The factor of two included in these permits appears to be provided as a factor of safety: therefore, caution should be exercised when applying additional factors of safety during the design process so that over design can be avoided. January 2003 California Stormwater BMP Handbook 5-19 Errata 9-04 New Development and Redevelopment www.cabrnphandbooks.com Section 5 Treatment Control BMPs In the third example, the Uniform Intensity Approach, the rainfall intensity is specified directly, and is not a func1ion of the location or time of concentration of the area draining to the BMP. This approach is very simple to apply, but it is not reflective of local conditions. The three example flow-based BMP design criteria are easy to apply and can be used in coi!junction with the Rational Formula, a simplified, easy in apply formula that predicts flow rates based on rainfall intensity and drainage area diaracteristics The Rational Formula is as follows: Q=CiA where Q= flowinfts/s i = rain intensity in in/hr A= drainage area in acres C = runoff coefficient The Rational Formula is widely used for hydrologic calculationa, but it does have a number of limitations. For stormwater BMP design, a key limitation is the ability of the Rational Formula to predict runoff from undeveloped area where runoff coefficients are highly variable with storm intensity and antecedent moisture conditions. This limitation is accentuated when predicting runoff from frequent; small storms used in stormwater quality BMP design because many of the runoff coefficients in common use were developed for predicting runoff for drainage design where larger, infrequent storms are of interest Table 5-3 provides some general guidelines on use of the Rational Equation. Table 5-3 Use of Rational Formula for Stormwater BMP Design Composite Runoff Coefficieut "C' BMPDramage Area 0.00to 0.25 (Amen) 0.26 to 050 051 to 0.75 0.76t01.00 o to 25 Caution Yes Yes Yes 26 to 50 HIgh Caution Caution Yes Yes 51 to 75 Recommended Not High Caution Caution Yes 6 to 100 I Not Recommended High Caution Caution Yes In summary, the Rational Formula, when used with commonly tabulated runoff coefficients in undeveloped drainage areas, will likely result in predictions higher than will be experienced under actual field conditions. However, given the simplicity of the equation, its use remains 5-20 California Strmwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabmpha,dbooks.com Section 5 Treatment Control BMPs practical and is often the standard method specified by local agencies. In general, use of alternative formulas for predicting BMP design flows based on the intensity criinna above is acceptable if the formula is approved by the local flood control agency orjurisdiction where the project is being developed. The following steps describe the approach for application of the flow-based BMP design criteria: i. Identify the "BMP Drainage Area" that drains in the proposed BMP. This includes all areas that will contribute runoff to the proposed BMP, including pervious areas, impervious areas, and off-site areas whether or not they are directly or indirectly connected to the BMP. 2. Determine rainfall intensity criteria to apply and the corresponding design rainfall intensity. FactoredFloodPlowApproaciz: Determine the time of concentration for "BMP Drainage Area" using procedures approved by the local flood control agency or using standard hydrology methods. Identify an Intensity-Duration-Frequency Curve representative of the drainage area (usually available from the local flood control agency or climatic data center). Enter the Intensity-Duration-Frequency Curve with the time of concentration and read the rainfall intensity corresponding to the 50-yr return period rainfall event. This intensity is the "Design Rainfall Intensity." California Stoiwnwater BMPHandbookApproack Select a ram intensity cumulative frequency curve representative of the "BMP Drainage Area." See Appendix D. Read the rainfall intensity corresponding to the cumulative probability specified in the criteria, usually 85%. Multiply the intensity by the safety factor specified in the criteria, usually ; toget the "Design Rainfall Intensity! Thu/arm Intensity Approach: The "Design Rainfall Intensity" is the intensity specified in the criteria, usually 0.2 in/br. 3. Calculate the composite runoff coefficient' "C" for the "BMP Drainage Area" identified in Step 1. 4. Apply the Rational Formula to calculate the "BMP Design Flosv' FactoredF!ood Flow Approach: Using the "BMP Drainage Area' from Step i, the "Design Rainfall Intensity' from Step 2; and "C" from Step 3, apply the Rational Formula and multiply the result by 0.1. The result is the "BMP Design Flow." Cahfornza Stormwater BMPllandbookApproack Using the "BMP Drainage Area" from Step 1, the "Design Rainfall Intensity' from Step 2b, and "C" from Step 3, apply the Rational Formula. The result is the "BMP Design Flow." Uniform Intensity Approach: Using the "BMP Drainage Area" from Step 1, the "Design Rainfall Intensity' from Step 2c, and "C' from Step 3, apply the Rational Formula. The result is the "BMP Design Flow." January 2003 Cailfbrnla Stormwater BMP Handbook 5-21 Errata 9-04 New Development and Redevelopment www.cabmphandbooks.com Section 5 Treatment Control BMPs 5.5.3 Combined Volume-Based and Flow-Based BMP Design Volume-based BMPs and flow-based BMPs do not necessarily treat precisely the same stonnwater runoff. For example, an on-line volume-based BMP such as a detention basin will treat the design runoff volume and is essentially unaffected by runoff entering the basin at an extremely high rate, say from a very short, but intense storm that produces the design volume of runoff. However, a flow-based BMP might be overwhelmed by the same short, but intense storm if the storm intensity results in runoff rates that exceed the flow-based BMP design flow rate. By contrast; a flow-based BMP such as a swale will treat the design flow rate of runoff and is essentially unaffected by the duration of the design flow, say from a long, low intensity storm. However, a volume-based detention basin subjected to this same rainfall and runoff event will begin to provide less treatment or will go into bypass or overflow mode after the design runoff volume is delivered. Therefore, there may be some situations where designers need to consider both volume-based and flow-based BMP design criteria. An example of where both types of criteria might apply is an off-line detention basin. For an off-line detention basin, the capacity of the diversion structure could be designed to comply with the flow-based BMP design criteria while the detention basin itself could be designed to comply with the volume-based criteria. When both volume-based and flow based criteria apply, the designer should determine which of the criteria apply to each element of the BMP system, and then size the elements accordingly. 5.6 Other BMP Selection Factors Other factors that influence the selection of BMPs include cost; vector control issue; and endangered species issues. Each of these is discussed briefly below. 5.6.1 Costs The relative costs for implementing various public domain and manufactured BMPs based on flow and volume parameters are shown in Tables 5-4 and 5-5 below: Table 5-4 Economic Comparison Matrix - Flow BMP Cost/th Strip $$ Swab $$ Wet Vault Not available Media Filter Vortex Not available Drain Insert Not available Table 5-5 Economic Comparison Matrix - Volume BMP Cost/acre-ft Austin Sand Filter Basin Delaware Lineal Sand Filter Extended Detention Basin (EDB) $$ Multi Chamber Treatment Train (MC1) WetBasin Manufactured Wetland Not available Infiltration Basin $ Wet Pond and Constructed Wetland 5-22 California Stamwater BMP Handbook January 2003 New Development and Redevelopment Errata 9-04 www.cabmphandbodcs.com Section 5 Treatment Control BMPs 5.6.2 Vector Breeding Considerations The potential of a BMP in create vector breeding habitat and/or harborage should be considered when selecting BMPs. Mosquito and other vector production is a nuisance and public health threat Mosquitoes can breed in standing water almost immediately following a BMP installation and may persist at unnaturally high levels and for longer seasonal periods in created habitats. BMP siting design, construction, and maintenance must be considered in order to select a BMP that is least conducive to providing habitat for vectors. Tips for mini Tnhzlng vector-breeding problems in the design and maintenance of BMPs are presented in the BMP fact sheets. Certain BMPs, including ponds and wetlands and those designed with permanent water sumps, vaults, and/or catch basins (including below ground installations), may require routine inspections and treatments by local mosquito and vector wntrd agencies to suppress vector production. 5.6.3 Threatened and Endangered Species Considerations The presence or potential presence of threatened and endangered species should also be considered when selecting BMPs. Although preservation of threatened endangered species is crucial, treatment BMPs are not intended to supplement or replace species habitat except under special circumstances. The presence of threatened or endangered species can hinder timely and routine mRintenance, which in turn can result in reduced BMP performance and an increase in vector production. In extreme cases, jurisdictional rights to the treatment BMP and (.•. surrounding land may be lost if threatened or endangered species utilize or become established in the BMP. When considering BMPs where there is a presence or potential presence of threatened or endangered species, early coordination with the California Department of Fish and Game and the U.S. Fish and Wildlife service is essential. During this coordination, the purpose and the long-term operation and maintenance requirements of the BMPs need to be dearly established through written agreements or memorandums of understanding. Absent firm agreements or understandings, proceeding with BMPs under these circumstances is not recommended. 5.7 BMP Fact Sheets BMP fact sheets for public domain and manufactured BMPs follow. The BMP fact sheets are individually page numbered and are suitable for photocopying and inclusion in stormwater quality management plans. Fresh copies of the fact sheets can be individually downloaded from the Caltrans Stormwater BMP Handbook website at www.cabmpbandbooks.com. January 2003 CalifornIa Stormwater BMP Handbook 5-23 Errata 9-04 New Development and RedeveIopmt www.cabniphandbooks.com Drain Inserts MP-52 Description Design Considerations Drain inserts are manufacluredfilters orfabric placed ina drop • inlet to remove sediment and debris. There are a multitude of Fit.and Seal Capacity within Inlet inserts of various shapes and configurations, lypicafly falling into one of three different groups: socks boxes and trays. The sock consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the gate of the inlet holds the sock. Socks are meant for vertical (drop) inlets, Boxes are constructed of plastic or wire mesh. Typically a polypropylene "bat' is placedin the wire mesh box. The bag takes the form of the box. Most box products are one box, that is, the setting area and filtration through media occur in the same box Some products consist of one or more trays or mesh gates. The trays may hold different types of media. Filtration media vary by manufacturer. Types include polypropylene, porous polymer, treated cellulose, and activated carbon. California Experience Targeted Constituents The number of installations is unknown but likely exceeds a Iff Sediment thousand. Some users have reported that these systems require 0 Nutrients considerable maintnnce to prevent plugging and bypass. 0 Trash Metals Advantages Batena Does not require additional space as inserts as the drain 0 Oil and Grease inlets are already a component of the standard drainage systems. RimeV.1 EIY&EIvemss Easy access for inspection and maintenance. See New Development and Redevelopment Hard3ook-Section 5. As there isnostanding water, there is little concern for . mosquito breeding. A relatively inexpensive retrofit option. Limitations Performance is likely significantly less than treatment systems that are located at the end of the drainage system such as ponds and vaults. Usually not suitable for large areas or areas with trash or leaves than can plug the macit Design and Sizing Guidelines Refer to manufacturer's guidelines. Drain inserts come any many configurations but can be placed into three general groups: socks, boxes, and trays. The sock consists of a fabric, usually constructed of polypropylene. The fabric may be attached to a frame or the gate of the inlet holds the sock. Socks are meant for vertical (drop) inlets. Boxes are constructed of plastic or wire mesh. Typically a polypropylene 'bag' is placed in the wire mesh box. The bag takes the form of the box. Most box products are ..t. January 2003 CalIfornia Stormwate- BMP Handbook 1 of 3 New Development and Redevelopment www.cthmphandbcoks.com MP-52 Drain Inserts one box; that is, the setting area and filtration through media occurs in the same box One manufacturer has a double-boL Stormwater enters the first box where setting occurs. The stormwater flows into the second box where the filter media is located. Some products consist of one or more trays or mesh grates. The trays can hold different types of medial'Filtration media vary with the manufacturer types include polypropylene, porous polymer, treated cellulose, and activated carbon. Con.truction/Inspecftoit Couaideratknta Be certain that installation is done in a manner that makes certain that the stnrmwater enters the unit and does not leak around the perimeter. Leakage between the frame of the insert and the frame of the drain inlet can easily occur with vertical (drop) inlets. Performance Few products have performance data collected under field conditions. Siting Criteria It is recommended that inserts be used only for retrofit situations or as pretreatment where other treatment BMPs presented in this section area used. Additional Design Guideline. Follow guidelines provided by individual manufacturers. Maintenance (.. Likely require frequent maintenance, on the order of several times per year. Cost The initial cost of individual inserts ranges from less than $ioo to about $2,000. The cost of using multiple units in curb inlet drains vanes with the size of the inlet. The low cost of inserts may tend to favor the use of these systems over other, more effective treatment BMPs. However, the low cost of each unit may be offset by the number of units that are required, more frequent maintenance, and the shorter structural life (and therefore replacement). References and Sources of Additional Information Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert Planet CPR, Seattle, Washington Interagency Catch Basin Insert Committee, Evaluation of Commercially-Available Catch Basin Inserts for the Treatment of Stormwater Runoff from Developed Site; 1995 Lany Walker Associates, June 1998, NDMP Inlet/In-Line Control Measure Study Report Manufacturers literature Santa Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project - Evaluation of Potential Catch basin Retrofits, Woodward Clyde, September 24, 1998 2 of 3 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphancibooks.com Drain Inserts MP* 52 Woodward Clyde, June ii, 1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint Source Pollution Control Program. January 2003 Clfbrnla Stormwater BMP Handbook 3 of 3 New Development and Redevelopment www.ctrnphandbooks.com Targeted Constituents / Sediment U / Nutrients U / Trash / Metals / Bacteria U / Oil and Grease U 1 Organics Legend (Removal Effectiveness) Low U High A Medium Infiltration Trench TC-10 Design Considerations Accumulation of Metals Clogged Soil Outlet Structures Vegetation/Landscape - -- Maintenance Description An infiltration trench is a long, narrow, rock-filled trench with no outlet that receives stormwater runoff. Runoff is stored in the void space between the stones and infiltrates through the bottom and into the soil matrix. Infiltration trenches perform well for removal of fine sediment and associated pollutants. Pretreatment using buffer strips, swales, or detention basins is important for limiting amounts of coarse sediment entering the trench which can clog and render the trench ineffective. California Experience Caltrans constructed two infiltration trenches at highway maintenance stations in Southern California. Of these, one failed to operate to the design standard because of average soil infiltration rates lower than that measured in the single infiltration test. This highlights the critical need for appropriate evaluation of the site. Once in operation, little maintenance was required at either site. Advantages Provides i00% reduction in the load discharged to surface waters. An important benefit of infiltration trenches is the approximation of pre-development hydrology during which a significant portion of the average annual rainfall runoff is infiltrated rather than flushed directly to creeks. If the water quality volume is adequately sized, infiltration trenches can be useful for providing control of channel forming (erosion) and high frequency (generally less than the 2-year) flood events. SQA !CaUfornla \Stormwater \ Quality Association January 2003 California Stormwater BMP Handbook 1 of 7 New Development and Redevelopment www.cabmphandbooks.com Infiltration Trench TC'-10 WQV = Water quality volume RFV = Rock fill volume SA = Surface area of the trench bottom The use of vertical piping, either for distribution or infiltration enhancement shall not be allowed to avoid device classification as a Class V injection well per 40 CFR146.5(e)(4). Provide observation well to allow observation of drain time. May include a horizontal layer of filter fabric just below the surface of the trench to retain sediment and reduce the potential for clogging. Construction/Inspection Considerations Stabilize the entire area draining to the facility before construction begins. If impossible, place a diversion berm around the perimeter of the infiltration site to prevent sediment entrance during construction. Stabilize the entire contributing drainage area before allowing any runoff to enter once construction is complete. Performance Infiltration trenches eliminate the discharge of the water quality volume to surface receiving waters and consequently can be considered to have 100% removal of all pollutants within this volume. Transport of some of these constituents to groundwater is likely, although the attenuation in the soil and subsurface layers will be substantial for many constituents. Infiltration trenches can be expected to remove up to 90 percent of sediments, metals, coliform bacteria and organic matter, and up to 6o percent of phosphorus and nitrogen in the infiltrated runoff (Schueler, 1992). Biochemical oxygen demand (BOD) removal is estimated to be between 70 to 80 percent. Lower removal rates for nitrate, chlorides and soluble metals should be expected, especially in sandy soils (Schueler, 1992). Pollutant removal efficiencies may be improved by using washed aggregate and adding organic matter and loam to the subsoil. The stone aggregate should be washed to remove dirt and fines before placement in the trench. The addition of organic material and loam to the trench subsoil may enhance metals removal through adsorption. Siting Criteria The use of infiltration trenches may be limited by a number of factors, including type of native soils, climate, and location of groundwater table. Site characteristics, such as excessive slope of the drainage area, fine-grained soil types, and proximate location of the water table and bedrock, may preclude the use of infiltration trenches. Generally, infiltration trenches are not suitable for areas with relatively impermeable soils containing clay and silt or in areas with fill. As with any infiltration BMP, the potential for groundwater contamination must be carefully considered, especially if the groundwater is used for human consumption or agricultural purposes. The infiltration trench is not suitable/for sites that use or store chemicals or hazardous materials unless hazardous and to materials are prevented from entering the trench. In these areas, other BMPs that dpi6t allow interaction with the groundwater should be considered. January 2003 California Stormwater BMP Handbook 3 of 7 New Development and Redevelopment www.cabmphandbooks.com Infiltration Trench TC-10 Exclude from consideration sites constructed in fill or partially in fill unless no silts or clays are present in the soil boring. Fill tends to be compacted, with clays in a dispersed rather than flocculated state, greatly reducing permeability. The geotechnical investigation should be such that a good understanding is gained as to how the stormwater runoff will move in the soil (horizontally or vertically) and if there are any geological conditions that could inhibit the movement of water. Maintenance Infiltration trenches required the least maintenance of any of the BMPs evaluated in the Caltrans study, with approximately 17 field hours spent on the operation and maintenance of each site. Inspection of the infiltration trench was the largest field activity, requiring approximately 8 hr/yr. 0 In addition to reduced water quality performance, clogged infiltration trenches with surface standing water can become a nuisance due to mosquito breeding. If the trench takes more than 72 hours to drain, then the rock fill should be removed and all dimensions of the trench should be increased by 2 inches to provide a fresh surface for infiltration. Cost Construction Cost Infiltration trenches are somewhat expensive, when compared to other stormwater practices, in terms of cost per area treated. Typical construction costs, including contingency and design ( - costs, are about $5 per ft3 of stormwater treated (SWRPC, 1991; Brown and Schueler, 1997). Actual construction costs may be much higher. The average construction cost of two infiltration trenches installed by Caltrans in southern California was about $50/ft3; however, these were constructed as retrofit installations. Infiltration trenches typically consume about 2 to 3 percent of the site draining to them, which is relatively small. In addition, infiltration trenches can fit into thin, linear areas. Thus, they can generally fit into relatively unusable portions of a site. Maintenance Cost One cost concern associated with infiltration practices is the maintenance burden and longevity. If improperly sited or maintained, infiltration trenches have a high failure rate. In general, maintenance costs for infiltration trenches are estimated at between 5 percent and 20 percent of the construction cost. More realistic values are probably closer to the 20-percent range, to ensure long-term functionality of the practice. References and Sources of Additional Information Caltrans, 2002, BMP Retrofit Pilot Program Proposed Final Report, Rpt. CI'SW-RT-ol-050, California Dept. of Transportation, Sacramento, CA. Brown, W., and T. Schueler. 1997. The Economics of Stormwater BMPs in the Mid-Atlantic Region. Prepared for the Chesapeake Research Consortium, Edgewater, MD, by the Center for Watershed Protection, Ellicott City, MD. Galli, J. 1992. Analysis of Urban BMP Performance and Longevity in Prince Georges County, Maryland. Metropolitan Washington Council of Governments, Washington, DC. January 2003 California Stormwater BMP Handbook 5 of 7 New Development and Redevelopment www.cabmphandbooks.com Infiltration Trench TC-10 CONCRETE PARKING LOT LEVEL SPREADER GRASS CHANNEL (LESS THAN I% SLOPE) PLUNGE POOL e BYPASS (TO OETENTIONFACILITY) >•" q' INFILTRATION TRENCH WITH PEA GRAVEL ALTER LAYER OVER WASHED BANK RUN GRAVEL , AGGREGATE OVERFLOW PLAN VIEW OVERFLOW BERM RUNOFF FILTERS THROUGH GRASS f OBSERVAT)ONWEU. WITh SCREW TOP LID BUFFER STRIP (20 MINIMUM); GRASS CHANNEL OR SEDIMENTATION VAII,T 2" PEA GRAVEL FILTER LAYER PROTECTIVE LAYER OF FILTER FABRIC TRENCH 3.8 FEET DEEP F1U.EO WITH 1.5-2.5 INCH DIAMETER CLEAN STONE (BANK RUN GRAVEL PREFERRED) SAND FILTER ir DEEP (OR FABRIC EQUIVALENT) RUNOFF EXFILTRATES THROUGH UNDISTURBED SUBSOILS WITH A MINIMUM RATE OF 0.5 INCHES PER HOUR SECTION January 2003 California Stormwater BMP Handbook 7 of 7 New Development and Redevelopment www.cabmphandbooks.com Targeted Constituents if Sediment A 1 Nutrients S ifTrash 1 Metals A / Bacteria / OH and Grease A / Organics A Legend (Removal ElI ctiveness) I Low U High A Medium Vegetated Swale TC-30 Design Considerations Tributary Area . Area Required Slope Water Availability Description Vegetated swales are open, shallow channels with vegetation covering the side slopes and bottom that collect and slowly convey runoff flow to downstream discharge points. They are designed to treat runoff through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Swales can be natural or manmade. They trap particulate pollutants (suspended solids and trace metals), promote infiltration, and reduce the flow velocity of stormwater runoff. Vegetated swalés can serve as part of a stormwater drainage system and can replace curbs, gutters and storm sewer systems. California Experience Caltrans constructed and monitored six vegetated swales in. southern California. These swales were generally effective in reducing the volume and mass of pollutants in runoff. Even in the areas where the annual rainfall was only about 10 inches/yr, the vegetation did not require additional irrigation. One factor that strongly affected performance was the presence of large numbers of gophers at most of the sites. The gophers created earthen mounds, destroyed vegetation, and generally reduced the effectiveness of the controls for TSS reduction. Advantages If properly designed, vegetated, and operated, swales can serve as an aesthetic, potentially inexpensive urban development or roadway drainage conveyance measure with significant collateral water quality benefits. X-C-ASQA CANwnin Storrnwat.r ' Quality Association January 2003 California Stormwater BMP Handbook 1 of 13 New Development and Redevelopment www.cibmnh,4hnnfrc i,'. TC-30. Vegetated Swale i Roadside ditches should be regarded as significant potential swale/buf f e r s t r i p s i t e s and should be utilized for this purpose whenever possible. Limitations . Can be difficult to avoid channelization. • May not be appropriate for industrial sites or locations where spills may occur Grassed swales cannot treat a very large drainage area. Large areas may be divided and treated using multiple swales. A thick vegetative cover is needed for these practices to function properly. They are impractical in areas with steep topography. They are not effective and may even erode when flow velocities are high, if the grass cover is not properly maintained. In some places, their use is restricted by law: many local municipalities require curb and. gutter systems in residential areas. Swales are mores susceptible to failure if not properly maintained than other treatment BMPs. Design and Sizing Guidelines Flow rate based design determined by local requirements or sized so that 85% of the annual runoff volume is discharged at less than the design rainfall intensity. Swale should be designed so that the water level does not exceed 2/3rd5 the h e i g h t o f t h e grass or 4 inches, which ever is less, at the design treatment rate. Longitudinal slopes should not exceed 2.5% Trapezoidal channels are normally recommended but other configurations, such as parabolic, can also provide substantial water quality improvement and may be easier to mow than designs with sharp breaks in slope. Swales constructed in cut are preferred, or in fill areas that are far enough from an adjacent slope to minimize the potential for gopher damage. Do not use side slopes c o n s t r u c t e d o f fill, which are prone to structural damage by gophers and other burrowing animals. A diverse selection of low growing, plants that thrive under the specific site, climatic, and watering conditions should be specified. Vegetation whose growing season corresponds to the wet season are preferred. Drought tolerant vegetation should be considered especially for swales that are not part of a regularly irrigated landscaped area. The width of the swale should be determined using Manning's Equation using a valu e o f 0.25 for Manning's n. 2 of 13 California Stormwater BMP Handbook January 2003 New Development and Redevelopment wwwrahmnhndhnnrr%rn Vegetated Swale TC-30 Construction/Inspection Considerations Include directions in the specifications for use of appropriate fertilizer and soil amendments based on soil properties determined through testing and compared to the needs of the vegetation requirements. - Install swales at the time of the year when there is a reasonable chance of successful establishment without irrigation; however, it is recognized that rainfall in a given year may not be sufficient and temporary irrigation may be used. If sod tiles must be used, they should be placed so that there are no gaps between the tiles; stagger the ends of the tiles to prevent the formation of channels along the swale or strip. Use a roller on the sod to ensure that no air pockets form between the sod and the soil. Where seeds are used, erosion controls will be necessary to protect seeds for at least 75 days after the first rainfall of the season. Performance The literature suggests that vegetated swales represent a practical and potentially effective technique for controlling urban runoff quality. While limited quantitative performance data exists for vegetated swales, it is known that check dams, slight slopes, permeable soils, dense grass cover, increased contact time, and small storm events all contribute to successful pollutant removal by the swale system. Factors decreasing the effectiveness of swales include compacted soils, short runoff contact time, large storm events, frozen ground, short grass heights, steep slopes, and high runoff velocities and discharge rates. Conventional vegetated swale designs have achieved mixed results in removing particulate pollutants. A study performed by the Nationwide Urban Runoff Program (NURP) monitored three grass swales in the Washington, D.C., area and found no significant improvement in urban runoff quality for the pollutants analyzed. However, the weak performance of these swales was attributed to the high flow velocities in the swales, soil compaction, steep slopes, and short grass height. Another project in Durham, NC, monitored the performance of a carefully designed artificial swale that received runoff from a commercial parking lot. The project tracked 11 storms and concluded that particulate concentrations of heavy metals (Cu, Pb, Zn, and Cd) were reduced by approximately 50 percent. However, the swale proved largely ineffective for removing soluble nutrients. The effectiveness of vegetated swales can be enhanced by adding check dams at approximately 17 meter (50 foot) increments along their length (See Figure 1). These dams maximize the retention time within the swale, decrease flow velocities, and promote particulate settling. Finally, the incorporation of vegetated filter strips parallel to the top of the channel banks can help to treat sheet flows entering the swale. Only 9 studies have been conducted on all grassed channels designed for water quality (Table 1). The data suggest relatively high removal rates for some pollutants, but negative removals for some bacteria, and fair performance for phosphorus. January 2003 California Stormwater BMP Handbook 3 of 13 New Development and Redevelopment nks.alnnAkaalee - - TC-30 Vegetated Swale Table 1 Grassed swale pollutant removal efficiency data Removal Efficiencies (% Removal) Study TSS TP TN NO3 Metals Bacteria 1rpe Caltrans 2002 77 8 67 66 83-90 -33 dry swains Goldberg 1993 67.8 4.5 - 31.4 42-62 -100 Irassed channel Seattle Metro and Washington 6o 46 Department of Ecology 1992 - -25 a—is - grassed channel Seattle Metro and Washington 83 29 Department of Ecology, 1992 - - 46—fl -25 graned channel Wang etaL, 1981 80 - - - 70-80 - hyswale Dorman et al., 1989 98 18 - 45 37-81 - day swale Harper, 1988 87 83 84 8o 88-90 - day swale Kercher et al., 1983 99 99 99 99 99 - fry swain Harper, 1988. 81 17 40 52 37-69 - Net swale Koon, 1995 67 39 - 9 - to 6 - et swale While it is difficult to distinguish between different designs based on the small amount of ( available data, grassed channels generally have poorer removal rates than wet and dry swales, although some swales appear to export soluble phosphorus (Harper, 1988; loo n , 1995). It is not clear why swales export bacteria. One explanation is that bacteria thrive in the warm swale soils. Siting Criteria The suitability of a swale at a site will depend on land use, size of the area serviced, soil type, slope, imperviousness of the contributing watershed, and dimensions and slope of the swale system (Schueler et al., igga). In general, swales can be u s e d t o s e r v e a r e a s o f less than 10 acres, with slopes no greater than 5 %. Use of natural topographic lows is encouraged and natural drainage courses should be regarded as significant local resources to be kept in use (Young et al, 1996). Selection Criteria (NCTCOG, 1993) a Comparable performance to wet basins a Limited to treating a few acres a Availability of water during day periods to maintain vegetation a Sufficient available land area esearch in the Austin area indicates that vegetated controls are effective at removing pollutants Fen when dormant. Therefore, irrigation is not required to maintain growth during dry periods, but may be necessary only to prevent the vegetation from dying. 4 of 13 California Stormwater BlIP Handbook January 2003 New Development and Redevelopment -- - wwwe2hmnhn4hifrc ra'.,n - - Vegetated Swale TC-30 The topography of the site should permit the design of a channel with appropriate slope and cross-sectional area. Site topography may also dictate a need for additional structural controls. Recommendations for longitudinal slopes range between 2 and 6 percent. Flatter slopes can be used, if sufficient to provide adequate coiveyance. Steep slopes increase flow velocity, decrease detention time, and may require energy dissipating and grade check. Steep slopes also can be managed using a series of check dams to terrace the swale and reduce the slope to within acceptable limits. The use of check dams with swales also promotes infiltration. Additional Design Guidelines Most of the design guidelines adopted for swale design specify a minimum hydraulic residence time of 9 minutes. This criterion is based on the results of a single study conducted in Seattle, Washington (Seattle Metro and Washington Department of Ecology, 1992), and is not well supported. Analysis of the data collected in that study indicates that pollutant removal at a residence time of 5 minutes was not significantly different although there is more variability in that data. Therefore, additional research in the design criteria for swales is needed. Substantial pollutant removal has also been observed for vegetated controls designed solely for conveyance (Barrett et al, 1998); consequently, some flexibility in the design is warranted. Many design guidelines recommend that grass be frequently mowed to maintain dense coverage near the ground surface. Recent research (Colwell et al., 2000) has shown mowing frequency or grass height has little or no effect on pollutant removal. Summary ofDesign Recommendations The swale should have a length that provides a minimum hydraulic residence time of at least 10 minutes. The maximum bottom width should not exceed 10 feet unless a dividing berm is provided. The depth of flow should not exceed 2/3rds the height of the grass at the peak of the water quality design storm intensity. The channel slope should not exceed 2.5%. A design grass height of 6 inches is recommended. Regardless of the recommended detention time, the swale should be not less than 100 feet in length. The width of the swale should be determined using Manning's Equation, at the peak of the design storm, using a Manning's n of 0.25. The swale can be sized as both a treatment facility for the design storm and as a conveyance system to pass the peak hydraulic flows of the 100-year storm if it is located "on-line." The side slopes should be no steeper than 3:1 (H:V). Roadside ditches should be regarded as significant potential swale/buffer strip sites and should be utilized for this purpose whenever possible. If flow is to be introduced through curb cuts, place pavement slightly above the elevation of the vegetated areas. Curb cuts should be at least 12 inches wide to prevent clogging. Swales must be vegetated in order to provide adequate treatment of runoff. It is important to maximize water contact with vegetation and the soil surface. For general purposes, select fine, close-growing, water-resistant grasses. If possible, divert runoff (other than necessary irrigation) during the period of vegetation January 2003 California Stormwater BlIP Handbook S of 13 New Development and Redevelopment www.cabmphandbooksorn _- TC-30 Vegetated Swale establishment. Where runoff diversion is not possible, cover graded and seeded areas with suitable erosion control materials. Maintenance The useful life of a vegetated swale system is directly proportional to its maintenance frequency. If properly designed and regularly maintained, vegetated swales can last indefinitely. The maintenance objectives for vegetated swale systems include keeping up the hydraulic and removal efficiency of the channel and maintaining a dense, healthy grass cover. Maintenance activities should include periodic mowing (with grass never cut shorter than the design flow depth), weed control, watering during drought conditions, reseeding of bare areas, and clearing of debris and blockages. Cuttings should be removed from the channel and disposed in a local composting facility. Accumulated sediment should also be removed manually to avoid concentrated flows in the swale. The application of fertilizers and pesticides should be minimal. Another aspect of a good maintenance plan is repairing damaged areas within a channel. For example, if the channel develops ruts or holes, it should be repaired utilizing a suitable soil that is properly tamped and seeded. The grass cover should be thick; if it is not, reseed as necessary. Any standing water removed during the maintenance operation must be disposed to a sanitary sewer at an approved discharge location. Residuals (e.g., silt, grass cuttings) must be disposed in accordance with local or State requirements. Maintenance of grassed swales mostly involves maintenance of the grass or wetland plant cover. Typical maintenance activities are summarized below: Inspect swales at least twice annually for erosion, damage to vegetation, and sediment and debris accumulation preferably at the end of the wet season to schedule summer maintenance and before major fall runoff to be sure the swale is ready for winter. However, additional inspection alter periods of heavy runoff is desirable. The swale should be checked for debris and litter, and areas of sediment accumulation. Grass height and mowing frequency may not have a large impact on pollutant removal. Consequently, mowing may only be necessary once or twice a year for safety or aesthetics or to suppress weeds and woody vegetation. Trash tends to accumulate in swale areas, particularly along highways. The need for litter removal is determined through periodic inspection, but litter should always be removed prior to mowing. Sediment accumulating near culverts and in channels should be removed when it builds up to 75 mm (3 in.) at any spot, or covers vegetation. Regularly inspect swales for pools of standing water. Swales can become a nuisance due to mosquito breeding in standing water if obstructions develop (e.g. debris accumulation, invasive vegetation) and/or if proper drainage slopes are not implemented and maintained. 6 of 13 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmphandbooks.com - - - -- - t Vegetated Swale TC-30 Cost Construction Cost Little data is available to estimate the difference in cost between various swale designs. One study (SWRPC, 1991) estimated the construction cost of grassed channels at approximately $0.25 per ft2• This price does not include design costs or contingencies. Brown and Schueler (1997) estimate these costs at approximately 32 percent of construction costs for most stormwater mnagement practices. For swales, however, these costs would probably be significantly higher since the construction costs are so low compared with other practices. k more realistic estimate would be a total cost of approximately $0.50 per fta, which càmpares favorably with other stormwater management practices. January 2003 California Stormwater BMP Handbook 7 of 13 New Development and Redevelopment www.cabmphandbooks.com I n Veaetated Sw..S Table 2 Swale Cost Estimate (SEWRPC, 1991) Cost Tstal Cost Low Modaret. H1 Low Msdats No Component Ustt Eiønt 1 $107 W4 8441 $107 SM 6441 Dw'n"-lin4ht Sib PMPBCAM 0.5 12.200 83,100 10400 11,100 $1000 $2700 0.25 83,100 1115000 $1,100 $110 $1,300 $1,150 aviafl' YO yd' 312 82.10 $170 on $711 no $1,378 $424 $1,172 $300 1,210 4020 1110.36 10.50 8s - SmiumpdTallooll 664 and Muldf.. YAP 1,210 lOAD $1.00 $1.10 $4U $1,210 $1,038 80 - YIF 1.210 $1.20 8240 1113.10 11452 8z104 54,366 subb"- - - - - $1,111 $6,311 $13,160 &MM 1 26% 26% 20% 11,278 $7,347 16,415 Told - - - - - $8305 $11.735$17075 ----.- iwl, N ' naianbsten TsWstoth.ogInicn end p1nkil kiahid In NshP a la. Sie Pie. a boflom width at 1.0 fo, stop wMaf 10 feet wIll 13 We slopes. 8W a 1,000400t length. bAles cidared = (top stdth .10 eel) x oslie idrh. 'Area Wubbed = (top width x wale legiglh). 'Vume oscaveted = (0.67 x top wldthx aid depth) x &We bnp (psiaxla os.-aebn). 'Area Iliad = (bp mAM + 8(swale dec0i'l z al. le (paølv# csa-selibr). Aiea seeded =areadearedz0.5 'Area sodded = area cleared x0. 8 of 13 CalifornIa Stomiwater IMP Handbook January 2003 New Development and Redevelopment www.cabm'"idbooks.com Vegetated Swale TC-30 Table 3 Estimated Maintenance Costs (SEWRPC. 19911 (Ospth Ii Thp ) 1.6 'ost o.pm, On.. 3.Fost 080ft 3.Fost Componsed Unit Cost Comment Font Belts. wwm. Reltam Z1Foot 1$.ontTepWlIth T.pwllm Ln Me *851 1,000 II'S nns $0.14 Itrfo 1021 lIrsvnt 1w meitem'cs uos.(p dl.10fosxlseh. M Gsu.rsl U Cern *001 1,000I.r $0.18 llhi.ifo 1020 llrsu' font L rnutiuuia. rs - cop swmb QISfld LI' 10.10 lIft1 SO.WIU@mrfad 1010 1Ifo - Girso A sss ii $0301yd1 $021 Ift"Wftd 10.01 11mw font Am um 1% UWWGQ4i5r dnlawi nhurs urns p.r '-F Pm - $0151 1mw ntIy $0.15 IIrf 10.1 lmwfont iup..42sg pu' 5 IflfIfL. plia $05! iipo1un TON - $S.1swfos* $L7SIsutsst - January 2003 California Stormwater BMP Handbook 9 of 13 New Development and Redevelopment TC-30 Vegetated Swale Maintenance Cost Caltrans (2002) estimated the expected annual maintenance cost for a swale with a tributary area of approximately 2 ha at approximately $2,700. Since almost all maintenance consists of mowing, the cost is fundamentally a function of the mowing frequency. Unit costs developed by SEWRPC are shown in Table 3. In many cases vegetated channels would be used to convey runoff and would require periodic mowing as well, so there may be little additional cost for the water quality component Since essentially all the activities are related to vegetation management, no special training is required for maintenance personnel. References and Sources of Additional Information Barrett, Michael E., Walsh, Patrick M., Malina, Joseph F., Jr., Charbeneau, Randall J, 1998, "Performance of vegetative controls for treating highway runoff," ASCE Journal of Environmental Engineering, Vol. 124, No. ii, pp. 1121-1128. Brown, W., and T. Schueler. 1997. The Economics ofStormwater BMPs in the Mid-Atlantic Region. Prepared for the Chesapeake Research Consortium, Edgewater, MD, by the Center for Watershed Protection, Ellicott City, MD. Center for Watershed Protection (CWP). 1996. Design of Stormwater Filtering Systems. Prepared for the Chesapeake Research Consortium, Solomons, MD, and USEPA Region V, Chicago, IL, by the Center for Watershed Protection, Ellicott City, MD. Colwell, Shand R., Homer, Richard R., and Booth, Derek B., 2000. Characterization of Performance Predictors and Evaluation ofMowing Practices in Biofiltration Swales. Report ( to King County Land And Water Resources Division and others by Center for Urban Water C Resources Management, Department of Civil and Environmental Engineering, University of Washington, Seattle, WA Dorman, M.E., J. Hartigan, R.F. Steg, and T. Quasebarth. 1989. Retention, Detention and Overland Flow for Pollutant Removal From Highway Stormwater Runoff. Vol.i. FHWA/ RD 89/202. Federal Highway Administration, Washington, DC. Goldberg. 1993. Dayton Avenue Swale Biofiltration Study. Seattle Engineering Department, Seattle, WA. Harper, H. 1988. Effects of Stormwater Management Systems on Groundwater Quality. Prepared for Florida Department of Environmental Regulation, Tallahassee, FL, by Environmental Research and Design, Inc., Orlando, FL Kercher, W.C., J.C. Landon, and R. Massarelli. 1983. Grassy swales prove cost-effective for water pollution control. Public Works, 16: 53-55. Koon, J. 1995. Evaluation of Water Quality Ponds and Swales in the Issaquah/East Lake Sammamish Basins. King County Surface Water Management, Seattle, WA, and Washington Department of Ecology, Olympia, WA. etzger, M. E., D. F. Messer, C. L. Beitia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side A Stormwater Runoff Management: Disease Vectors Associated With Structural BMPs. Stormwater 3(2): 24-39.Oakland, P.H. 1983. An evaluation of stormwater pollutant removal 10 of 13 California Stormwater BMP Handbook January 2003 New Development and Redevelopment - - - Vegetated Swale TC-30 through grassed swale treatment. In Proceedings of the International Symposium of Urban Hydrology, Hydraulics and Sediment Control, Lexington, KY. pp. 1-182. Occoquan Watershed Monitoring Laboratory. 1983. Final Report: Metropolitan Washington Urban Runoff Project. Prepared for the Metropolitan Washington Council of Governments, Washington, DC, by the Occoquan Watershed Monitoring Laboratory, Manassas, VA. Pitt, R., and J. McLean. 1986. Toronto Area Watershed Management Strategy Study: Humber River Pilot Watershed Project. Ontario Ministry of Environment, Toronto, ON. Schueler, T. 1997. Comparative Pollutant Removal Capability of Urban BMPs: A reanalysis. Watershed Protection Techniques 2(2):379-383. Seattle Metro and Washington Department of Ecology. 1992. Biofiltration Swale Performance: Recommendations and Design Considerations. Publication No. 657. Water Pollution Control Department, Seattle, WA. Southeastern Wisconsin Regional Planning Commission (SWRPC). 1991. Costs of Urban Nonpoint Source Water Pollution Control Measures. Technical report no. 31. Southeastern Wisconsin Regional Planning Commission, Waukesha, WI. U.S. EPA, 1999, Stormwater Fact Sheet: Vegetated Swales, Report # 832-F-99-006 bttp://www.epa.gov/owm/mtb/vegswale.pdf. Office of Water, Washington DC. Wang, T., D. Spyridalds, B. Mar, and R. Homer. 1981. Transport, Deposition and Control of Heavy Metals in Highway Runoff. FHWA-WA-RD-39-1o. University of Washington, Department of Civil Engineering, Seattle, WA. Washington State Department of Transportation, 1995, Highway Runoff Manual, Washington State Department of Transportation, Olympia, Washington. Welborn, C., and J. Veenhuis. 1987. Effects of Runoff Controls on the Quantity and Quality of Urban Runoff in Two Locations in Austin, Th. USGS Water Resources Investigations Report No. 87-4004. U.S. Geological Survey, Reston, VA. Yousef, Y., M. Wanielista, H. Harper, D. Pearce, and R. Tolbert. 1985. Best Management Practices: Removal of Highway Contaminants By Roadside Swales. University of Central Florida and Florida Department of Transportation, Orlando, FL. Yu, S., S. Barnes, and V. Gerde. 1993. Testing of Best Management Practices for Controlling Highway Runoff. FHWA/VA-93-R16. Virginia Transportation Research Council, Charlottesville, VA. Information Resources Maryland Department of the Environment (MDE). 2000. Maryland Stormwater Design Manual. www.mde.state.md.us/environment/wma/stormwatermanual. Accessed May 22, 2001. Reeves, E. 1994. Performance and Condition of Biofilters in the Pacific Northwest. Watershed Protection Techniques 1(3):117-119. January 2003 - California Stormwater BMP Handbook 11 of 13 New Development and Redevelopment TC-30 Vegetated Swale Seattle Metro and Washington Department of Ecology. 1992. Biofiltration Swale Performance. Recommendations and Design Considerations. Publication No. 657. Seattle Metro and Washington Department of Ecology, Olympia, WA. USEPA 1993. Guidance Specifying Management Measures for Sources ofNonpoint Pollution in Coastal Waters. EPA-840-B-92-002. U.S. Environmental Protection Agency, Office of Water. Washington, DC. Watershed Management Institute (WMfl. 1997. Operation, Maintenance, and Management of Storm water Management Systems. Prepared for U.S. Environmental Protection Agency, Office of Water. Washington, DC, by the Watershed Management Institute, Ingleside, MD. 12 of 13 California Stormwater BMP Handbook January 2003 New Development and Redevelopment www.cabmohandbnnlic mm Vegetated Swale TC-30 MOM I. •Lit (b) O 1,iIIvIswof,ws Ip-i4.,sa,. 01 1.Nolens*.d$uk(ftf W •T*lildIuèat *( Z .R d dips January 2003 California Stormwater BMP Handbook 13 of 13 New Development and Redevelopment www.cabmphandbooks.co t'.. Attachment 11 Storm Water Standards 4103103 3. volume J. Volume-based SNIPs shall be designed to mitigate (Infiltrate, filter, or treat) the volume of runoff produced from a 24-4ait 85e percentile storm event, as determined from lsophMai maps contained in the County of Son Diego Hydrology Manual. Kil Flow 2. Flow-based BMPs shal be designed to mitigate (Infiltrate, filter, or frdat) the maximum flow rate of runolt produced from a rainfall intensity of 02 inch of rainfall per hour for each hour of a storm event. I. Stntural Tmatnient BMP Selection Procedure Priority projects shall select a single or combination of treatment BMPs from the categodes In Table 4 that maximize pollutant removal for the particular pollutant(s) of concern. Any pollutants the project Is expected to generate that are also causing a Clean Water Ad section 303(d) Impairment of the downstream receiving waters of the project should be given top priority in selecting treatment BMPs. To select a structural treatment BMP using the Structural Treatment Control BMP Selection Matrix (Table 4), each priority project shall compare the list of pollutants for which the downstr am receiving waters are Impaired (if any). According to the 1998 303(d) lsUng, the Ague Hedlonda Lagoon Is Impaired for sediment and siltation. Buena Vista Lagoon also has impaired beneficial uses (aquatic life) due to high sedlmehtation!eiltallon. Portions of Carlsbad where construction sites have the potential to discharge into a tributary of a 303(d)or directly Into a 303(d)water body or sites located within 200 feet of an ESA require additional BMP Implementation. These water bodies Include the Pacific Ocean, Buena Vista Lagoon, Encinas Creek, Agua Hedlonda Lagoon. and Satiquitos Lagoon. Priority projects that are not anticipated to generate a pollutant for which the receiving water is Clean Water Act Section 303(d) impaired shall select a single or combination of structural treatment BMPs from Table 4 that are effective for pollutant removal of the identified pollutants of concern determined to be most significant for the project. Selected BMPs must be effective for the widest range of pollutants of concern anticipated to be generated by a priority project (as identified in Table 1). Alternative storm water SMPs not identified in Table 4 may be approved at the discretion of the City Engineer, provided the alternative BMP is as effective in removal of pollutants of concern as other feasible BMPs listed in Table 4. SKDOCR PROTECTED BYPASS COARSE SCREEN MEDIUM SCREEN FINE SCREEN:. - l8J TOP. VIEW I now specifications Anew Th Squivi AN 00 4m Sow* "PAN Res hc , 41 ToW (b roux sas 5o..i 18 • 31.2 1.3 ou swam 10*18060 512 313 213 0.5 — ___ Idal 81* 12.8 si 2.4 akM aW Dr FLOW Wf F rAl&D now RAFE r4stak" db I. - robe" cm 110W Wm 81D 0W uvmgwmw *Foam 14 STlN 1004 SKDUIER THROAT GRATE TURPLENcE DEFLECTR T.'k1 4 a a a. :. • • a . [CONCRETE STRUCTURE ,s awi ev .e BOX MANUFACTURED FROM MARINE GRADE FIBERGLASS I GEL COATED FOR UV PROTECTION 5 YEAR MANUFACTUREWS VARRANTY P A TENTED 'L FILTER SCREENS ARE STAINLESS STEEL GRATE INLEr SKIWiR 8OX IOR FLORIDA DOT ?WE x !4VLeT .STRUCThweS. I C4OVC GRATE1 I INSERT GISB [$INSTALL GRATE I 7/ I fl/SivIc5s, ?c.a,;side, Cl 92049 ...... -24"-..... TOP VIEW • fYN SQIMIJC SID� VI� .. : Flow Specifications ,,u ........... ,..,.,... ,,. r«u-•• .......... ...., -,., 141003 &7 f..J CJ IIDJID nor, IIUI" rotaa,_.. NIii ...... 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The outside covering will no clog with sediment, allowing indefinib stormwater penetration, all the way to the cente of the boom. The absorbent filler is Absorben W. and is made from reclaimed paper mill by products. It is certified by Green Cross as 1009 recycled material. Absorbed liquid is drawn inti the cellulose fibers through capillary action aru locked into the boom. This process prevent leaching and draining which is a commoi problem with polypropylene booms. Absorbs Hydrocarbons On Contact 0 Absorbs 2-3 times more volume than polypropylene 0 Absorbs up to 14 times more volume than clay 0 Absorbs immediately on contact OAbsorbs and retains up to 7 dines Its weight oRetalns absorbed hydrocarbons; prevents leaching Oft is hydrophobic . will not absorb water o Works in all temperatures, sub-freezing to hot iude ?roa o100% organic. environmentally friendly Olt is not toxic to humans or the environment o ft will biodegrade naturally If lost In the environment ONo dangerous fumes when burned 0 Incinerate at low temperature with less than 1% ash Recycled Material Flow Specifications cps - fti-ow raw Mçhs. if raw fwa mood fox ISIS 1.116 36 I. -J6 Li_ fLOW Sulam •TURN X mt *71 I 23.6 I 142 I £2 maomm Soma IOU 10 - sox 231.d 12*1 *4 Man ra ati PWW *BMW 14 iv 0 mmh SU 2IYJ *7.1 tao fltT n.cw asir I miw nv art raw oaf i* rowtiu at ... Rm -•:_ sub owwxio TI4ROA1" TLMIILcIIcE • KrLEC7EIR .a a. SIDE VIEW - - SKMCI PTEC1ED •V 3YPAS$ 25 0 - ---MEDIUIISCREEN - -_ FINE SCREEN I BOX MANUFACTURED FROM MARINE GRADE FIBERGLASS & GEL COATED FOR UV PROTECTION 5 YEAR MANUFACTURERS WARRANTY PATENTED ' FILTER SCREENS ARE STAINLESS STEEL -V.. L - 244' : a END'1EW a' NCRETC STRUCTURE!.:. lOvC CRATE INSERT GISS REINSTALL GRATE GRATE INLET SXJ.WMER 30X FOR FLORIDA DOT INLET STRUCTURES. 9Iô C'an 7i7i Svc .c. ,cO 3.0m J169 ENVIRONMENTAL SERVICES, INC. Grate Inlet Skimmer Box Curb Inlet Basket Nutrient Separating Baffle Box REPORTS & DATA Pollutant Ladlng Analysis for Stormwater Retrofitting In Melbourne Beach Florida Pollutant Removal Testing for A Suntres Technologies Grate - Inlet Sldmmer Box site Evaluation of Suntree Technologies, Inc. Grate Inlet Skimmer Boxes for Debris, Sediment And 011 & Grease Removal 1 .d1i444JjIIfjj. 3 ;( CLUi]A, CA iiq.t .I4i_) a a * ! I•? ''' ' Pollutant Loading Analysis For Stormwater Retrofitting In Melbourne Beach, Florida By: Cordon England, PL Creech Engineers, Inc. 4450W. Eu Gall. Blvd, 0232 Melbourne, P1.32932 Introduction At Gemini Elementary Scheol In Melbourne Beach, Florid., t h e r e h a s b e e n a history of repeated flooding on the aelmol grounds and h a p r o p e r t i e s a d j e c e n t t o t h e s c h e o L I n 1999 Qeech Fn!"e*s, las. ((al) was dmsen by Brevard Cou n t y S t o r m w a t e r Utility to design d&"gt mnl to alleviate *Am Gooft conditiosm . a s w e l l a s t o provide Aw 'dommatm ftbaft vkh1a this 20.06 bectere d z abege basin. The project was divided Into twa phases. Phase 1 Lvem , wem med. In order to acceicçate inithi flood control measures fr homes dowrntneam ofthe scheoL Phase 2 Involved the design of mere amodn flood and water quality coutiOl measures along Oak Street for fluthar protedlon of sebool propa' and road w a y f l o o d i n g a t n e a r b y c h u r c h p r o p e r t y . This paper 1dgb11ghtà the political chalngn of retrofitting stormwater systems In developed areas, as well s demonstrate s a m e t h o d o l o g y r p e r r m b i g a m i ç o h * source poliutaât heAlng analysis. Eilatlag Conditions Gemini Elementary School is located on a 8.02 hectare, triangular shaped property a l o n g the south side of Oak Stmetq a two lane collector road is Melbourne Bee c h , a b o u t o n e half mile from the Mlai*k Ocean. See Exhibit 1. ResidentiA properties He downstream Of the scheol, along Its southeant and southwest b o r d e r s . $ 5 1 h a c t a r . D o u g F l u t l e P a r k I s on the north skis of Oak Street A soccer club uses the park sod school grounds on a daily basis. There was an stonuwder system at the p a r k , s n u g O a k S t r e e t , o r o n t h e s c h o o l site. Storanwatar flowed southward off Doug Pbitie Park, aoss Oak Street, through t h e school site, and into dhe yards and homes south of the schooL These yards, and the roads downstream of them, are very flat and Only a few &d above sea leveL Case water stages high enough In the yards, it gradually sheetflow s d o w n t h e a d j a c e n t r o a d s a Lew hundred yards to do Indian The acted hon1eowners naturally blamed th e s c h o o l f o r allowing the schooFs water to flood them. West ofthe school, a few ed yards along Oak sfrct, was a low point in &a road where water ponied and flooded the road and anadjacent churchyart Due to a thin clay Ie a at 26 cm deep causing a perched water table, waterstood in 1aroad forevecaJ days after even a aozninal rainfall. This drainage basin was almost 'opetcly uiit ct, with ao easy path for developing outfalls to relieve flooding. This nctionof the India River as Class 2 water body, witha Shellfish Harvesting classification intense scrutiny from the St. khoi River Watt Management DLstrLct Corp of Engineers pennitting is reqiked fir new 0utlk in the area due to seassseS new the sinrel1ne The park, lit sehool, and Oak Street He in n'ibrporated Brevard County. The chur c h , and properties west of the school are In Melbourne Beach. Being a collector road, all of the taility conisna have major tranmlisha lines In the road right-of-way. As can be sees, this challenging project involved Brevard County, Melbourne Bea c h , t h e School Board, Brevard County Parks and Remeetlan Department, Brevard Comf y R o a d and Bridge Depmmnd, Brsvaid Courty Stouuwatar Utility, $ clench, three Ajfl 1g RomeowitI Muocktloni, a soccer 666 the water Wargouat District, the Colp of Engineers, and several utility compenW. Stakehath htvolvsznei* and partne r s h i p s w e r e going to be critical to weave a aohzthn through the many players Involved. Proposed Improvemeefs The &at priedty wan to alleviat, flooding in the homes adjacent to the scho o l A s a n interim rnessur a berm was designed and constructed by County personnel along the south property lines of the school, with a swal, Wihi& the berm diecting water to the soielnnmat point of the school property. At that location, an Inlet emi 1$' outU pipe were coasthicted in a utility cavne' tlEough twa heavily landscaped and AmeW yards, to Pompano Sliest, where it was tied Into an exiatbig storm drain pIps A slant time later, heavy rains overflowed tho beans and swales and flooded home s adjacent to the school spin. CEI was engaged at that point In provide more effective - Fortunately, OMW Elementary School bids significant area of vacant land on their sit.. The school e.ileied Into Weemeaft with Brevard County allowing the constru c t i o n of tines dry retention ponds totaling 2.95 hectare to reduce flows leaving the school site, as well as provide storanwater treatment w'e sons existed. These dry ponds were wound around, several soccer and baseball field.. The soccer field's locations bad to ren*in in place due to previous agreements with the school and Parks and Recreation Dept. The ponds were only 2640 cm (12"- 181 deep and sodded, allowing the soccer teams to use the pond areas as practice fleids when dry. When the ponds were excavated, the confining clay layer was removed to allow for ioflltration though the beach said at the site. Construction was scheduled during the mun= when school was out. A control structure was designed at the outll pipe location to Prov ide protection for a 25 yen starm The temporary connection to the existing downstream pipe had overloaded the downstr.azn system in a heavy rain avent, so a new out&lI to the kdIn Riy.,r as designed through a park idjacent to the River. The park was owned by a Homeowners Association, which reluctantly gave a drainage easenit tbrough.the park. 11 County agreed to maka several improvements to the park and its boat ramp in exchange fi)r the casement. The Corp of Eqbm wan concerned that the new outfl pipe discharges would bV&ddmarby seagrasses, sothonewdiechargi pipe was not permitted to be constructed in the Indian River. A bubblsup box was designed to Ad back from the shoreline and rock riprap was placed between the bubbleup box and the mean high water Um to prevent erosion. As =Vpdn fK distinbing the shozeflne 4W*A and other plants Ware planted aimng the rocks to hti bur the simselins from the stormwater discharges This first pbM of improwin'ti was fimIded In September 2000 at a we of $124,000. luimmmmimb heplemented proved siacceasM In preventing any flooding of adjacent homes In several large rinIl. in 2001. Th, second phase of do project ad4reae4 stormwater qiiantiay and quality concerns along 1650 inetsis of Oak Street, bin AlA to (2mly Street. To provide fin*er flood protection at G R1em'rtary School, retn swabs wars designed abng both sides of Oak Sliest and 625 ms of storm drain pipe was 'Iceigned to ioIeie* numff and prevent It from crossing the rued onto school propedy. The piping also jwovided an onttW1 low spot 1fltheroMbythednrcb. This new pipe systen discharged Into a residintlal canal $)5 WhiCh was used by many of the adjacent residents for bo.thg to the fn liver Lagoon (By). Tines cwn1 ware very politic* aens1th since they win In need of dredgIng and dn Town of Melbourne Beach does nd dredge malL Ths rmida concerned tint tin new stoanwater system would lend to Inilna aedIme&don of the c"1'- Mw ." alteiitifLve for treatnnrd was to use lath at the church site (or a pond for the roth runeft The church W" willing to donate the ]ad where thá septic tank fields ware located if the County would provide a sewer connection. This scenario was designed, but when it came time (orthechwchtogivecsacitatthsCow,theybelkedandd was back tothe a- St. Johns River Water Maigcierit District, (District), aiterin requires stormwater treatnnx* (or , hnpruvcmenis which a) nicreass discharge rates b) which Increase pollu#mt loadings, or c) which increase impervious areas. With this project, in new increased impervious areas were proposed, bit there would be additional water flowing to the csLdentW canal from the extnsioa of the pipe system to the flood prone areas. linse raw flows create thC potrtial for meased pofl!atsit lodipga to the canaL Normal design methods would have used freathacit ponds to offset these potential impacts. Due to lack of available land for ponds, a1tntive treatment mednda were proposed for this project. The District will consider alternative treatment methods if it can be demonstrated that all other possible alternatives have been exhausted. It would lot be ,ossible politically to use more school or park area An Weatinent. ponds. Forzhis project, CE! showed that the only alternatives were to tear down houses for ?ords, or use ate-oat Leeatineut tcrnoloes. The treatnrn strategy involved niaxhnizing treatnnt methods within the project b a s i n with akernative BMPs, as well as rdrofitthig two adjacent watersheds as ad d i t i o n a l mitigation. A total of 1.67 acre feet of retenlknt atozagn isa provkled in Phase 2 in the roadside swales AM WAU1)oadL This was equivalent to 0.032 inches of retention f r o m the drag. an" swing to the reteflfioñareaL A treatment train along Oak Street was designed by 'ishig 9 Grated Inlet Slrlmmr Boxes, from Suntree Tedniiloglei, Ins., in the new Inks to trap dclxii enterin g t h e i n l e t s , stnding bern' to slow runeff from the bell fields, and installing one baffle box at the downeam end of the new pipe system along Oak Street. Raffle Boxes are Wine - - devices which trap sediment, tr* and dthdL They have been used byBdCEc!flyflwthehst9yearL Inok Buis 4,whicb o n 1 y had one existing baffle box to provide sedhnea* rmneval, 16 Cob Inle t S kbmw Bous ware btstallad to all of the existing Wets to provide redrisat removal by trapping grass cllpphip, Wnv4 and yard debris. N1xlents un a onomin in the i'1' sines the radnisets prearots aigne bicoan, which in twa hwresss umwk bolid up in th e c . ' I ' - I n ofMts dralneis Baa 5, bm m 3 which dlscbsrga dfrectly to the c*niis Three baffle boies and 6 curb Inlet ddmm boxes wm designed to provide mdlm'it and mitrient treetnst far this dgs basin. Brsv&d County Stormwater UWq will Implement this project and be zesponilbis far all inhlnte,iince of the lWovemats. The baffle boxes wilL be Inspected twice a year and cleaned as needed. liii inlet traps will be cleaned twins a year. Breva'd County has a vacuum truck dedicated to cIenng storrowater BL. Using numerous BMPs used on this project provided a high degree of teatmnt far dii new piping system along Oak Street, and provided trebnent far two ofiblie basins w h e r e We treetm'& e'dstct The retrofitting of the ofiio areas was, In ect, mitigation for dii new discharges to the cmiii. See B,thlba 1 far a map of the Iinprovcnieids. Calculations In Phase 1 of the project, the day ponds and outfall pipes were modeled hydraulically using the Interconnected Pond Routing program. Shies the dry ponds in the Phase 2 project area were too small to provide effective attnution, the predevelopment and pod development rUnoff calculations were made using Hydraflow and the rational inethed. The only available storm drain pipe for Phase 2 was a 36" pipe in omits Basin 4. The new piping along Oak Street was connected to the existing 36" pipe, and the piping downstream of the connection was upgraded to a 42" pipn. The pipes were designed for a 25 year storm. Basins I and 3 were a much longer distance from the outfall than Basin 4. As a result of different times of concentration, the peak flows from B a s i n 4 passed sooner than Basins 1,2, and 3, giving only a slight increase in peak discharge, despite adding 12.25 hectares to the area flowing to the existing outfall. The poteit:al for iicasd Othaaa loaddizgs ii the car.al ws ct :ocal cm.sidmits. These 'aiaJs had a history of diediAg perations wery 3-10 yrs, aid the residents did not want to increase the fteuency of costly dredging. The main polkitsitta of concern leading to muck deposition in the canals were Total Suspended Solids (TSS) TOW Nitrogen (iN), and Total Phosphorus (W)1 Sediment build up at the end of the pipe was conunon. Nutrient ks4iIIga from grass clippings, leaves, and ftrtilizs leads to alga blooms and low dissolved oxygen in the canal., which in turn leads to muck bilid up from the emill ophication process. Most of the material dredged from residential canals is typically muck. To address this concern, a pollutant loading analysis of the existing aid proposed stormwater discharges was perfi31me& In the existing conditlona, the only stounwater treatment in to and system was a bff1s box along Cheny Stied fir ofihite Basin 4 of 24.24 hectares, fle were a total of 7 outfIt pipes discharging into dw canal system. In the first phase of this project atarmwater ueMmit was provided ibr 8.02 boctares of the school grounds with 3 dry detion ponds. The discharge from these ponds was to the Iialinn River, radw than the canal system, so these poltdant loads wac not imbxled htthepoflutait losfrtlmcaimloutf&IL The existing pollutdzt kid to tim cermi only csmo from drainage Basins 4 and S. totaling 31.2 heatam lim ruroff from Oak Street did not drain to the canal in existing condMugu only In tim post devslopmei* ooivlltL tim alaLegy br tim pollutant analysis was to caloulate to polkitm* loads In the existing conditions, wA then calculate the pollutà bails after the new pipes were added to tim system and omits area retrofitted fir dormwater 1retmø Tim polhitait. used in this analysis were TSS, TP, and TN. Each drainage basin was categorined by laid use. Meal, nnnJ wass loadlogrataftom wStounwata Loig Rate Parameters fir Central and South Flouts", Harper, 1994, were nxiklplied by each basin's area to give existing and potential annual pollutant Ioadinge See Table I. tim next step was to calculate the pollutant removal rates for the diffi!rent BMPs. Individual BMP removal efficiencies were take from "A Guide fir Me Selection in Urban Developed Mess", EWRI, 2000. What was challenging with this analysis was the use of multiple BMPs in series for the treatment train. Each SM? receives cleaner and cleaner water as the water moves down the train. At each BMP, the removal efficiency for each constituent was multiplied by the reniainr,g percentage of the initial loading to give a weighted, cumulative, removal efficieroy fir each constituent See Table 2. These calculated removal efficiencies were than multiplied by the total calculated pollutant loads to give the reduced pollutant loadings after the BMPs were installed. See Table 3. hble 4 dows that the total loads to do canal wen reduced as a re k of ,su the trofitting of onsite and offsite basins. The olItnt loading analysis e!ow otra th3t s a ragLlt :'f teous 31'iA?s coposed, the tottl pollutant loadings ajitaring the canals after project conipleton will actually be significantly reducedfrom the adsft pollutant loadings entering the caiIg. lie key to overall pollutai* reduction is to provide additinnal treatnent in oiTsite drainige basins. This will reault in a net he'fit of reduced poftwis entering the canals and a reduction of tie severe flooding often seen along Oak Street. Table 1 Exisdig Pollitast Loading Area Basin !!!1 Land (lea Loading RaW Potential Pollutant Loading TSS ToW los$!flis ToW !.!! T$$ 05 omw ftfl Riaor 7.0 !!!2A 0.040 1.07 70.15 Total t a 1.11 76 o.0 1.07 0.74 j 0013R&ii4u 04$ 1.07 % is ii 0011a 0.048 1.07 11 o.om IM 2E 2M_ .•.. 4. q,pis 1.07 15.09 0.121 2.814 2F 1.07 0marw 7.6 0.040 1.0T j 0.011 2.101 26 0.71 R In .ift. 0$ 1.07 070 1 0.015 .P! .211 1.36 'Moroi•.. -RIC 7.1 tOT 980 I 0.080 1.380 us A-me NMI.. it. 9.0 - 107 0.61 I 0064 2J as MEMM 7.6 9.OIS jQj_ um I 0.017 I USS I,. am...J9L. 4AS 1 0.018 a. Om 7.6 0.0. JL_M . 0.016 . 0.364 3A 2.11 55.1 • 0504 4.88 136.85 1.301 10.246 38 3.01 50.1 0504 465 160.42 1.104 14.134 30 4._ LwlntaMII 2.813 6$ 1 .71_ 5T 4 50.0 .9 fa.L 55.1 0.514 486 072.00 24MO 280= IA 60 55.1 0.5I 488 3.805 21.112 58 3.82 15.1 0.504 4.59 483.59 5.136 40.342 2.66 511 0.694 1.601 12.542 8utaI 71.1 4.66a 113U 5.13 360.23 Totals 101.38 3461.6 41.30 .I2$J4_ * From "Stormwater Loading nato Parameters for Central arid South Florida, 1994. Harper **33$jfl 4 has an axlsthg baffle box providing treatment. 3as1ns 4 and 5 are the existing pollutant loadings to the canals. Tablel BMP Poltutiat Removals EMP POLLUTANT REMOVAL TABLZ BMP . 3MP Removal Efticlenc'j Typ• Tfl TP TN yPu 81 81 91 80 48 23 fllsBcx 80 30 0 nITr09(eratad 790 jj 10" 99.0 91.0 84.2 TMb_______________ rdd TM 1* em 1 04_ 37.7 10 en ___________________________ 81.1 85.3 75 d8pIs BW PWhdW R.movd Calculations TSS - 10$+ (1040).73 + (10010.14L8)to.8 = 98.9% Removal - 1Oth.48 + (10"W79 4(10G.45.4AI) • 91.9% Rem,at Th - 10thc.25+ (100.25)x.72 = 842% Removal Dry Pund+InITnp(g)4Bm1IsDox 118— 100tO.86+ (100.86.73 4' (100.85-10.05)io.8 • 09.2% Removal TP - 10(kO.61 + (10041)x0.79 + (100.81-30.8)L3 • 94.3% Removal TN - 1ObL01+ (10091)it.19 a 9S.1% Removal id Trap (C) + 8.l5s Smi TSS- 100-xO.2+(10020)xQ$- 84% Removal TP - 100t0.11 + (10041)c.' 377% Remal TN - 1OOx.1O 10% Removal Hlot Trap (g)+ 3afts 90a 38 - 100J3 + (100-73)x0.30 • 31.1% Aemval TP - 1O.19 + (100-79t0.3 a 353% Ranavol TN- 1O0x.7979% Removal All MOM vies are 1mm '(iulde For BM Manaemerd Practice From Creeds Engineers study "Pollutant Removal Tasting For a Suntrae Tachnologles Grate Inlet Skimmer 8cx", 2001 "From visual observation by Brevard County staff 2o4sl Pollutant Loading I TabI. 4 Met 2olbitant 2emovals TSS (ki&r) TP (kglyr) TN(kgi'yr) predevelopment 3015.7$ 35.13 3*0.83 Postdcvelopment 630.97 21.95 2*9.15 Net Reduction 23*4.81(19%) 13.18 (37.52%) 91.68(24.07%) Summary The days of solving flooding problems in communities with simple ditch and pipe solutions iave disappe&ed. 3Awiroa1ienLaL cocerns ow ctae Laat c.jwjrc eateit techniques be intr2td into these flood clief projects. By Adfirig wtr çiality components to water quantity projects, communities can help achieve pollution remediatlon goals being established thr NPDBS, TMDL, and PLRG programs Retrofitting existing stxmwater qdeme to provide water quality tresbat Is more complicated, cxpeailvoi ad time colwmllng then &it"nel stormwater designs Sr new development. The scarcity of available had and nnnwou$ aicisting utilities in older built Ott areas will lax an engineer's imanJiithn to provide inxvative SMh in these locations. An Cai'efiilly pkawd tre't'u' tin was desIgId conaisthig of swaics, ponds, berma, baffle boxes, and Inlet traps to provide overall etonnwater pollution reduction. In order to address doimwster po1bton comarns, treatment mitigation Was designed in oita Am b, min bulm The poThit* leadings and remevais were calculated using a simple but ccthe spreadsheet analysis incorperathig the latest in BMP efflciey shdieL While complicated atormwater modeling software can be used kr pollntan* aillysis, this typo of modeling Is mere coat cctive on lerge basin studies than ismill bum and hviduul projects. The m poTh rainoval calculations ahewed nmiaI j reduction of 79% thr 158, 37% the Total Phespherus, and 24% the Total Nitrogen In the Oak Street basin despite the creation of a nm stoundrain system thr a landlocked area. As this project demonstrates, there are typically mmurm abbaldees that need need to be heougitintothe pzojeetearly ineproceas and bapt processfrougbontfl lithof the project. Mai meetings were bald with city, county, and state officials, boxasownea associations, scheols, soccer clubs, churches, and utility connqL All it take. Is one uncooperative stakrhelder to set beck or. kilL a project, as was dnmenskatd with the church backing out of th5 land acq1t1on process after ''w verbal Indications of approval. Using creative partnershipe with other entitlas and agales allowed the development of a unique strategy to solve flooding at several locations in the project area. References ASCE- "Guide For Best Management Practice Selection in Urban Developed Areas", 2001 Gordon England, P.E. "Pollutant Remeval Testing For a Suntrec Technologies Grate Inlet Skinuner Box', 2001 Harvey Harper, Ph. D, PI., "3tormw3t3r Loading Rate ?arametes for CavitraI and South Florida", 1994 POLLUTANT REMOVAL TESTING FOR A SUNTREE. TECHNOLOGIES GRATE INLET SKIMMER BOX Prepared for Suntree Technologies, Inc. November 2001 CEI Project #21121.00 Prepared By: ..si :9 "I I S.•••. . .. ... .................. j1j a \4u,rY' IFfl C''JP.flA1IOL .. . 434) W. f C Me 2v19 St's. 232 IL :3293.4 (3fl) 251.k5:!3.I vm Background I Methodology 2 Rásults 2 Tabb I - Sodkmnt Sbw AnaVels 3 Concksslons 3 APPENDIX A )'lltiPhotos APPENDIX B thilvsrual Engln.ulng Sciencis (Drab mist 8k1inm.r Box '1 Evak1smlon Report 4411l1p8u.1 I UFi2 11111111 1iiii 1w 41 El iJJ!i Iiffhjni;:; h!ijJ! •1I'e I- JJf1Jj 11IJ!ij H I kL4 SIP Ij. Poo LI 1 1' Ii'jliif o u, V tqJp;i1 1iajfj III 01 A 4Hja' il 0 a s j 411.10 111111 ii ii IiJIIt 1 I .1 j1I'i1I III aIq!Jj1 iiitflhi iiIIIiIaii.I;.. I1 W4 t!!P PM' ssv2 jo unowt jw wci W= .pV., io SMA W.M. piAO oi: uiv ooq n qFno 'suis a.zso ao vloq MOIit'C ZqIN iGsoLuoxoqaqn ,pIawM aU Wfl3t =a m qhoaq P HSID 9W &qAvg amm flt .p jo ipoq 1upn :1flu$ Twollm P° 'pSp 'RSID vpuiq pz $D& WWW a Vm k."spp,3g £pood v a PU!1ibIFP =a #qL 11 'q Zi pa siq vowow at a usv lUpu 'I$4vu owa&as * w 9M.Mift II$Ufl opaI*u aiis IU!au usif It0aq1 ,g so= so-wilm 'IXON 1Dd GOP WWW NIL p=mmftoWppjL I$ aIjp psuud n* uiue £zaizoqr çp 'çDI&o iq smpcwaqw evu 01 v- no s* MR xW la wqpq =mop s*a 'psqP I= ''.pp 'isiu ow wq pi =a I1 'MU! is oi mi ous pt&nan ijo i y 'zcq oqs x' 01 F=ww F= ORA GOP P qqp M, st on P aw pk=w am MA IqL I*$ SP Jo-, up pmoa mop —_11ju1a * psdaq ape uq wo up pqt pssoqo RM çqupopçpaasn$ up pmsrppmCvwq mqMoma vqiI1lflf u* 'Lj (c, I1)wI ç3o OW * $1 MU! upj ($ 0J mp& 0100Z pdaqasp am * M&Vma =on V 1U!U! up GM PNO " BSR) =AP 'a v MUP pgpft p= ppaq UM VIM. up jo VI,?JPthL $U1 L0 aI)$n$ pr '01111 unj. _ UUidIuU UJO lVU!d&) gv uu11 og u 1s0eilap liup jo ai poij ON. '013 f u SRPI up paAas%o 'j IRM*oa WOND &Ift4Lv1 piu40 pwr-w"iAuJI '1UI$I 1 pi s____ lu_jign o3tJztInpMnzçu01)*0oe!q psp&oid 4m aois q5us *0003 Opp 1s spuof ipyc .g *0003 'wiy p*axa WUM 009 V WR pzv11 e o p iqp. u' 01 ijo 4" of ___ &0 use 01 pwU1p V ___ 11U11w psqoup MR am= 01 paqubsi .q pn um— o imw eJap %wh UIMW0$ so MN $qiu 1upoAo.d mp WR upjo wooq upjo 1a Llplvi ipp poio dos 01 'USE) GjwA U! p0*2uu%t !S av scq u-z".a npm up °M wm.m imp vm wm MA in "'DI *up PU!'P 46661 io ipoq up oiu i op çq 'quspmujo amo v qq gSiO 01() Uq sppp paiC pu ioj VvAjo dn pn sv &juzouag q oiq qp !iqwog pa $UUjP00 4IoOq1e3oip4j 031%Id,O 01 pwUDp 4p =d u 43t sdv PM PQddvA 30 U015UadSnS0J wpm. M. 01 ollid 1 TW!P 18! xoq up offiop AlmjR 3noqv the inlat. This situation is MY COOA is 1t3 due to loose toleraancs' constfllctlofl techniques. In the sass teat, 6.51 lbs. of grass were washed into the mint and 5.22 lbs. were captured, reiu1thi1 as 1.36 lbs. of pass passing through the GM This repres e n t s a reniovai efficisany of 79.3%. The panted grass smrçb bad a Total Phosphorus coidid of 950 mglkg and a 1KM content of 510 mglki The pass sample renwved torn the GISB had a Total Yni plmrus coded of 2,270 ngikg and TEN co"ted of 905 mglkg. IIe sedbud tog was a No MW complex. The WthI nmb showed that of the 57.87 Lbs. of sedime" ithoducedto the (0Th, 42.41 lb.. weve ct*4 #ftatoth1nasss roiuonl effickany of 73.3%. Unlveisal &bsserh b1Lip, dig the Pided amçb bad la? % gravel, *8.0% and, and 1.4% * lbs Pot to amiçh bad 25.9% gravel, 14.7% sand, aid 1.7% clay. OMW is comsitlared to be partlok. NO aid larger. S i k wd qls4upsps No. 200sisv. Tablol Sediment Slave Aubrals iSine W No. 41 No. 60 N& 100 N% 209 r.m Pawn- '1 IDWhkW=WW 94.3 No.4 M19.2 89.3 65.8 50.3 25.5 1.4 81.8 74.1 442 31.3 14.7 1.7 5.5 15.220.61 18.5 1 10.8 1 -0.3 At the Ibw rate tamed, the 0188 ruved 79.3% of the gr Ip,li,gi washed into 1L the abll&y of the OTSB to &eve peas dhig large &ws wl water passes through the bypass bolos was not tested. In FlorIda, 90% of the doi= se low r.bdfl events of 1"orlegis low flows dMGw to do tegconIhIftn1 The makestheGlSBa MY ecthe Me $r Low flow events. It 1. WIMoval how ecdve the 0158 works inlargedormevants. By keeping pass aid other trapped organL debris ins day state, the u1rCnb is the debris do not loedi od aid beooun dissolved 0tid4 and pimaphates. 1 (088 is a MY cctive BMP fOr preventing nutrients from organin debris Ivom, ntui n g waterbodies. 11 $igni&eil knem is adrieag coeuktlon after the ted in pr0b3b13r attributed to the use of wastewater renas water during tim ted. Tim grass matted several iaches hickintlm bottom of the box Ther coWd ve acted asafiiterto &emove nutrients from the water source. At the flow rate of 1.1 c, the 0153 bad a zedirnnt z•moval fflicy of 73.3%. As would be expected, most of the Irapped sediment was gravel and sand, with atle jre iiatera1 colected. Th, NSB a eadh t a'tes á/31cg e oud i many structural 3W3,:9 a Nxtion of the COA la without druptive CO1CtOi1. 1fl UNIVERSAL ENGINEERING SCIENCES C. teak * Gj.iwtg $20 Brevard Avinus • Roddadgi, FlorIda 32955 (321) 831080$ FM (321) 6310978 November 2, 2001 Mr. Gordon England, P.E. Creech Engkieere, InA 4450 West Eau GaS. Boulevard Melbourne, FlorIda 32934 Reference: Greta inlet Skimmer Box Evaluation Northwest Corner of South Brevard Avereie and 8iá 5 Street Cocoa Beach, BWYWd County. Florida Universal Pro" No. 33189-002-01 Universal Report No. 51419 Dear Mr. England: Universal Engineering Sciences, Inc. (Universal) has completed an raltalon 01 a Greta Inlet Skimmer Box (GISB) in accordance with Universal Proposa l N a . P 0 1 - 0 7 8 1 . T h e w v A i a t i o n w a s conducted to doaanei* the Pollutant removal effectiveness a t fem ft. a ed a A Location Map. Site Map and Site Phoagrapha are presented a s A t t a c h m e n t s 1, 2 and 3, respedivoly. Sediment Testing Universal supplied to sediment sample for the GI$B evaluatio n . The sediment sample conaletad 01 tIns aside, coarse grain sandi with crushed s t e k , a n d graveL A gradation analysis of the sediment sample (8.1) was perfom4 prior to GISB perfonnanos testing. The percentages Cl soil gains, by wekK retained on each sie v e w e m e a s u r e d a n d a g r a i n s i z e distribution *M,g0n@f0bK to determine the textural nature of the sample and provide a control (baseline) prior to fleldwork. A sediment sample of known weIght (57.87 ibs.) was placed on the pavement upstream 01 the GISB and washed Into the GISS with a portable water source simulating a storm event The captured sediment was then removed from the GISB dried and waighed. The captured sediment weighed 42.41 60. resulting In a loss 0115.46 lbs. from the GISS tasting. A gradation analysis of the captured sediment sample (8-2) was perfoirnat Universal completed particle size analyses on the two representative sediment samples (8-1 and 5-2). The samples were tested according to the procedures fo r mechanical sieving of ASTM 0 422 (Standard Method for Pailde Size Analysis of Soil s ) . I n p a r t , A S N 0 4 2 2 equires passing each specimen over a standard set of nested slaves (% !nch, No. 4, No 10. No. 40. No. 4 ,\10. 100, No. 204 The percentage of the soil grains retained on sach sieve size are determined to provide the grain size distribution of the sample. The distribution determines Ula t3XbJ(si rature of the scif san,p!a and aids In vatuatfr.g its .3n9111a311419 c'actaisZIcs. £4'. Gordon England A'ojecf No. 33188002-01 Noven'betZ 2001 Report No6 51479 page S-I consisted 110.1 percent waval (918111 she 1arer than 4.75 mm), sao percent sand (grain size between 0.075 mm and 415 mm), and 1.4 percent fines (grain an less than 0.075 mm). &2 consisted d 25.9 percent gravel, 72.4 percent sand, and 1.7 percent fews, The grain size distribution curiae are presented as Mtadimant 4 According to the LMifled Sol a-- I System (USCS SI and 5-2 we dassifled as poc4graded gravely send [liP), Based on the. gradation analysIs the major portion of the lost sediment was the fine sand component Grass Clippings Test The grass cipping. were supplied by Sunbee Technologies. A grab sample of grass (G-I) was aoiected and eubnitted for laboratory analysis to determine the 1104 (EPA Method 351.2) and Total Phoephona (EPA Method 385.3) content A grass sample of know weIgi (L58 lbs.) was - on the pavement upstearn Of the GISB. The grass clippings ware washed into the 0150 in the same manner es the eedIsrd sample. live cspbad grass dippings were then removed from the 0180. tsd and weighed. The capbxed grass cpigs weighed 5.22 lbs resuithig in a loss of 1.36 be. A second grab sample (02) was oclieded from the captwed grass cpings and eathm5tod for laboratory analysi, to determine the removal efficiency for 11(14 end Total The eampjss were shipped in PC&B Laboratories, Inc. in Owledo, Florida. Laboratory analysis documented 960 mNllgmms per IWograrn (mglKg) af Total Phosphorus and 510 mglKQ of 1101 for 0-1. Laboratory analysis documented 2270 maftg ef Ta Phosphorus and 906 mglKg at 1101 for G-2. Laboratory Analytical Results and ChsInf-Qwtody Documentation are presented as AttachmentS. Universal appreciates the oppotbinfty to provide en*onmental seMces as part of your project team. Should you have any questions, please do not hesitate to contact tho undersigned at (321) 638.0808. ReasectfuIIy subrnftted, Universal Engineering Sciences, Inc. d me StaScientist II (2) Addressee Attachments Attachment 1: Site Location Map Robed Man Speed Re&nal Manager Rockledge Branch CifIce Attachment 2: Site Map Attachment 3: Site Photographs Attachment 4: Soft Gradation Curves Atachmant 5: Laboratory MaIticai Rasults and Chab1-of-Citcdy Ooc,arao, 8479 ;4b YAaJon fipat,!cc I-. ATTACHMENT 2 SITE MAP I - RESIDENTIAL CONDOMINIUMS V V I U C L4ND8CAPED MEDIUM J RESIDE TLAL - CONCRETE DRAINAGE S'NALE a SOUTH 8Th STREET RESIOENTIM.. CONDOMINIUMS I U4I'IERS.L Grate Inlet Skimmer Box Evaluation 3cuth avard aou:.av-d Cccca 3each, 3ravard County, F!oiida 311E 2':IAP J. .DA.'a3 I I I AOAvQ ATTACHMENT 3 SITE PHOTOGRAPHS Grate InIat at 600 South Brevard Awn; Cocoa Grate Inlet rnmórBox Features Storm BocrnN Zip Sldmmorltay Dettedilon Shield Flange Is reinforoe / ! 'vtthlu111ted1808±45. biaxial ilbargiass p • . .. _. ' I! • • :' ,.'.• /:;.::':...i I. ?a1ixat r.o'aL Tsi !or *1o s C=ta f1t 3'&er 2ox AT2 2fif!GA$J -4... :.. sedbum rL'-Lg 0183 1. Sediment Trapped in GISS ;1•' '4!'J • ••..•.• . ?oUttait Ramoval Testing for a &tro Technologies Grate Liet 3!danr Box m ThOTOG2A2S GISB Tneñcd hito TnI Uias Tsitg I ?ollutaat ov1 Tt Lbt i 1 ••'\ (t atikfrd Tchnoiojes Grate i1t H IhI2d1 czr 3ox Sfl' 2F1OTC GAb.3 I Sedimeit Thtitiig \1:. :• •q 'U JI( -. ',:•, :• i ')c ; :• ?oZhitaut Rraova1 Thsting for a &mtre TthnO!OgeS Grate Tiiet Box ITZ PifOTOC.AP113, IN i;f:( ;'. . I'. I J ic7 S r,c yI r -i ., - I.. ' p ¼.: J , d -' . ) J ' -; ' '1 , I ( t?i :: ____ : I - -. t4 / I / -:i i ;f I \2 •. S. - r .i --• S - , • S •. S ••;• , -- - - -. 5 h.3 :- S. i_ - , S 5, _5 . I - - . 5• 55 S - it -S.- •_'.• S U. .-.- r - S S - • - 'S I S S -- Si I ,• -_ 'L • 0 - 5, - ' S • 5_ 5 5 5.5 5 , • S 1 ' 0 I'\-'S • . - S -S I ATTACHMENT 4 SOIL GRADATION CURVES IiIIl1ll1UIl'i1 II tuIIIIII1IulI_iuiuuu____ III II.1lII1IU!UlIltlIl1III 1111111 11111111 iii_i'i"u' aIIIl1iaaIllllIil-IulIlI 11111111 iil_:i- 011111 iiii IIUlIIIII II ____IIIlUl 11111111 iul__1111111 UIIIII IlIt 1111111 ____Ift 11111_11111111 ____ III 1111111 RIIUI IIl*!IIII_1111111_0111111 111 1111111 RIIIII 1IIIIIh!IIRIIIIIIIl 11111111 ____ iIIII1IIII RIIIII lll1IllII1R1IlIIIl 11111111 iii-uiiiiu aiiiii IuI.lIIIIIil.IlIuuIu 11111111 ____ Ill 111111 IIIIl IIUIIIIII1lII!I1lII IIIIuIIl_ ilUIftll1IIaIllI IIIaII1InIialft1IIll--uIIIIII___ IIlIftIIIIUIlflhI1UIIIIII1111[IIUl-III1IlIl___ illlftlilli alull Ill RtHIIIIIIUIIIIIUIIIIIIIlU___ III1UIIIIRIUIIIUIIIIiIlIII1II11IIlU IllillI.- iiiaiiiiuiaiiiiiuiaiuiiiiiiiiiiii___ 1111111 iii•i iiiiiaiiiii iii aiiiiii iaa iiui iii iiiiuuaiiui I.aIIIuIIaaI:lu.R iiiiiia MC%U. PL N co Cs .Isi G.fl $T I $EDWJB4TI Sp.dmendlciIftlLslion 0100 • 010 flGczssl %Sand %SI 31 12.I ia.i 38.4 IA om IIIIIiIIl1U all ild lull w i ll II1iIiiIIIIuu 1111111 III_II;1IIIII.1I1I IlIRIUlIlIlI ____IIi1III__IIIIIIIU____ III lFIII RlII IIIRIIIIII1I___IIIII1I IIiIII _- III ____I1I iiIRiiiiiiiiRiIIlii1U•IiIiiIi 11111111 III lI1iIluI Ruth Iii Rillhlill ____iii•iiui 11111111 III fthhIII 111111111 ___iiiiiiii___ uiiuii____ III II.iIIII Ruth IIIIIIhu1.IU uiiiiuu___ iiiiiii___ iii iiiiiii mitt" II.RIiuiuIRII liii 11111111 III ___Hhh1ll RIUhII1URIIII IIIII 11111 11111111 Riuii iui Will i IRIII iuu ___ IlIlUlIT IIl—Il1.hIII RUtH IlIRilill LkURuI iiuiiuuiuiiui___ ii - iiiiii miuii uimuiti niiRui hII,u —uhuluuu." III HIU1I miiiui IIIRIlIh1iIiRII 11111 11111111 iuimiiiiui Ruu1IulIuuIIn.IIII 11111 11111111 I IIlUIhIII RIIIhIIIIRIIIhiI1IILIIIuiuI 1111111 I ii ii liii miuti IIIR1IIIflIIkIIIIIIII_lluhlull IIIlUiIIIRllIII1IIRlUhIiUlIIiiiiiiiiiiiii ____ iisu'iii'. mliii, iIlRIII1IIIuRIiuIui 11111111- I Iam Spst ![in OR I I cbodkaft. u. pi. pi ct cm Spedmen 1dm i% 0100 C80 030 DIG - I 12i0 I 1.11 mm O.11S As 72.4 1.7 341 3i$ NO.4 N0.10 NO.40 1 NO. 10 N0.100 NO. 200 74.1 32. 442 J 311 147 1.7 J ATTACHMENT 5 LABORATORY ANALYTICAL RESULTS AND CHAIN-OF-CUSTODY DOCUMENTATION L\ PC&D Environmental Laboratories, Inc. 210 ParkRoad, Oviedo, florIda 32765 Phone: 407359.7194 Fax 407359-7197 UiMmaI Enneedng Sdances Conta: James Mans Wevord Avenue Phone: (321) 635050$ Rodd.dgl.FL 32955- Laboratoiy RefaAncs Nombr: 201090199 Projest Name: Irdet 8l*uiisr Bo* Evatuatlon Pr*ct Number: Chain of Custody: 24025 LaboratoiylD Ma* ClentiD atatus Oatw71m.8umpie 2010901094 9old 04 RUN o9F2er2001 1420 I EPAIOIO PlIOlIOIUS by tCb'P IEPA 22KOS2 TOM Pagon PC&B Environmental Laboratories, Inc. 210 Park Road 0v1do1 FL 327654801 407-359.7194. (FAX) 407459.7197 Case Narrative James Maine Unlvsrs EnQkeSIIØ 8dnc 820 Ereverd Avenue Rodde., A. 3295 CASE NARRATNE Ibr. Wouk Order 201091)1 a. *ctNmnbsr Pmjod Name Inlet 8ldmmet acxEvstuaeon M cwee Neir3ft is s summaly of evanis andlor oroams encountered V4th the Work Order. 'aly.i. for '1'i wee ]performed by IavtxonmntI. 3ci.o.cs Corporation (E87487). es. • L • OE MIavl%*s. : V • Midti . A. WMI3QI Ot4&4T4I?1I4 kSflS mmtw RPadovMatvs1s 2010101914 44 PRUMNAMMMObow9ft Ecø EPA 0200012 nh 510 itcad. T:.3 vua :Ii t%3 ii :s Zia L for 41M illJi. 3u;ts ;aoortdd on i Wt Waflt ;,aIs. EP CompdXPP# 900134G - FCO4 Cadiflcation E832b Quality Control Report for Spike Analysis INORGANICS Lr _ — PW=Rt Co* Omm 1aut -I 1fr ' iái Ad - iIIIIIIIIIIIIII 'I__iIIIIIiIIIIIIl I-___:_IIIIIIlIIIHI - -IIlI1IIIlIIII IRIURRIRERIlU _______.IIIIIIIIIIIII rlu.uIIIIIIIIIIIII • tlIIIIIIIIIIIII tt!!IflhIUIIIIII ______IIIiIIII1IIfl ______IIIlIIIIIIIII -IlIIIIIlIIIlI IllIllInhIn j - !hhlhlhhhhhhl __iiillllllllllll ', auuauaaw: III - ______IIIIIIIIIIIII lIIIIIIIIlIH - NIIIIIIIIIIII,I-__-IIIIIIIIIIIII IIIIIIIIIIIII - IIIIIIII1IIlI IIIIIIIIIIIN -.IIIIIII1I11l'I: -1IIIIIIIIIIII -IIIIIIIII1IIII :: --ililninini IIIIlIIIIIIfl !U1liIIUIIIUI r1wj__ 1111111111111 __.Rp .••RR••a • a m - '11 411,11 ,.. Labaratoilos, Ins, .ad, R. 3vs61IO1 C EPA ZW12 Ude(actad. fl13 1a1u1 )rCadIn(th5 Vis ta Lfor the anaa. a'.ts .aoitod Ott a Wat W Cont,QA?P 9GG114 OOH Certification - avawid by - A PC&B Environmental Laboratories, Inc. 210 Park Road, Oviedo, Florida 32165 Phone: 4074597194 Fac 407459.7197 CReM: LWv'4 Eidneei'1 ldences Canted: Bob Speed Phone: (321) 8384M Roddsdgs,FL32955 Laborathiy Reference Number: 20110011$ Pi* Nwnbir: ømbi dCuodp :20344 __ Cuto Ddflm 2011001 IS-I SON mm 10110001 I EPA WII PheIomIbyicAp EPA0W35t2 OCT 9 20 ULU U Quality Control Report for Spike Analysis INORGANICS mm upw $1 $p Pow Ccu* Ch R L Ikffa S11W O& PI laws MwmftmTdd IlU 19O to IS no SiTE EVALUATION OF SUMREE TECHNOLOGIES, INC. GRATE MW SKIMMER BOXES FOR DEBRIS, SEDIMENT, AND OIL & GREASE REMOVAL Qé -Dbidd PbnnL1g & Ph'e'Iiig Dqiaiti Ede SDAC Speclaild SNM=dff I ow j the haft ce PUM le ow ____ god mw bathe, b di hed &imi vdaçmui*_a aliuii* Iivr d m* al the =am"W4=, pivkIu4 l she vkaeie Cweig devskçm* 'd dà need msj d a. i*d àd. m of dies - - it pu&U pie&a4alutA4 Whenever aew &V&oo or iedidaçmci occu di *es Is Isougit to omit oâper sequkannesi 1* di InIm, aiveed ices is in. need air tepid, acdv., and eoofcs1 Intovemg In the quft of its stonnwat, discharge. Switns Tedi1cies fnneporaPd, ocaLmd In Cz4is Cesavced, II mumbewm smwat s Iu!* Mmmer boese. They is made of s ft queli fibesom !ini with stainless steel flIt screens backed by hesvy.&q alimilnms pft is custom M06 to accomfliodats vedous Wd sizes. A by&ocaiboa absorption boom is itached im he top of di !dmmer box tw ck01euee, on, and pease mcvat These devices & bs!ow di irate and catch .ed1men4 'd&k and p".=4 ails ases. Cleao.out, mafiftanA and perfbritance repoiing is piovided by Suntrec on a 4eduled b* i'ictue o Gete hd cimnr Box the Rec4 ciiek !ñpmvent D(RC1D) selected sk (6) tag sites in the Lake mama Vista es to ovabists lbs pslmnaxs of dices imita One unit was placed in a anb inhe along Had PIM Ridvid bp laleci leaf litteç sedliusast, and oa & grease from abgh me roadway. Thee (3) units wm placed in dw backstage service area (if ths Rain Fond Cadi 1 (2) units warn placed in thebkstsge service an of to McDonald's restairait and Lagos merchandise shop, After several field meetings, during which Suntree eok extensive measumemente, photos, and other donunentation of each stamwater drain, the Gate mit Skimmer Boxes wer e mchund and delivered for flitJllatii. All sniti were hstaUed withoit Miap approidniately fto weeks babe the 1999 Ch dam holiday season. The zpt time oriod for paiticle catohment was one month. & Henry aid Torn Had, Suuee Technologies, visited each site several times during the month to wsm that debiis would iot fill the wits too on On Januaiy 2S,209 S'intrø riiced &e ix At each site, the mramid aptured n the skimmer boxes was eznoved, measured, weighed, visually identied, phctophed, -,j d_ cre va .itIy leld cifed Ic •p!ia oc& Al units pdaieedMnoiLcIawrap, &I di diaL The - of debis viled coniidenr Hc Phu ( w) db wai 90% Leof litisr aid IS u&nod N là Fiest CIA dm b litiff aid dpa bdts aid 50 *lm.it The àddb iekt was 60 %idbi'* and 30 % led hftv 00% m1c1111n5*15) In Wd doss the Wo wan 95% ssdlmn* aid 5% Ieaflthei1 ddMCDOIl$1de&1S an wa,inthrtothothaThe db ___ di lierwu 9% ___ aid 5% leaf littm no sW close to die thir gate was 9$% ft asbn.* aid 2% led li This composition is indlcive of the humai activities aid diásge flow patterns of that sits. Bxkstaga aces in die Wak Diaiey Woitd Resoit mosivo an atificial nfa avot each nit di in* cleaning operationt This wadis a coiithtual flow over the bi i p e r n o u s sits, wasbhg all xnateiials hits the stosmwater system. Municipalities in Bvakd, Vohâ and Dade counties aas wcessfliUy ised i1 a t -Ai=6 in i10ndi C1D pamcd with Wdt Disnsy Lnainesiing CNDI) iWeanh id Development to coordinate some basin chemical asapling for polliant removal aciency deterahiatios. ?k. Cralg Debwy, WDI, povided chnicd suppcit and danc fr this. An ingeniously imyb device was fabdcated by Sus ailow sampling of the First Flush of water going hits the units arid ultimately coming out of the kimimr boxes. - Co1ktd swOu j by th. EivkanMl Ssvi L. Ayab — watt ttmAI%1k (inI Oqpa Dan4 Peal Ci" Ø1PN and )Iitatà, ToteF Kj*hl Nicm. 011 ad O"w Total PbpT)u*Pt. $q)1Ja.J. and MddL Ara4yii nwb ate pi*scolsd in the Woft btk Ps6Nut S AMLY Lffi0N LAW -NIX VALUE UMJT$ $*M.oTI GhMW CMa. 1641 038 10 OFabO0 0.14 31% An OUT 1141 023 GS0O AnnnIi, RF.cUr4 1046 0.21 No I8''00 chowom QW06ft d RF-N 1040 2810 I8OO 1036 RFOUI' 1048 1180 go 03410 ChtaI Clow DuMad RRXff4 164$ 1430 "I O&OWW10 Co1m Flaw WN W4N 1640 1600 000 ml CC0 43400 Cm, Fwaw ww RF4w 1643 160$0 000 ml 0S'FsblO Com, wwkd UPtI W4Xff4 1648 30000 0100 ml. GS'F'0O whrow ow fr1I I44 1648 0.60 'l $40O QLQ8G sid mus RRW 1148 0.04 034e610 NS1tiia ow NO& M'OUT4 1848 0.01 00uFab'OO NW4 Toted VJ'iI W4N 1041 24.3 OI'FebOO 13.66 N&OWA Totid Pj" RF.OUT 1146 104 no 03Feb10 Nlb' TOW KWO JW6=4 1146 11.1 iI 080O ON wd bII IWO WSI W10 288 — drA O% 6 au pmean WA lbs 3W. for Amwk ad 6 amiam 74% 6 Oo4ifn b kn.4 dor m AW dWpW $0 1ds cc AMMIL 02 ml a 64 nw. 6 'M.l ml adow of Ab psIk AQaW nid. w.. cs ___ umbmL utant Removal Efficiency I $ rJ.fl44&PO1bkM1 1,10 tLEM JMRONMENTAL SERVICES, INC. The Callfoma Curb Shelf Basket Water coadizeds P.-' r-- I as I *.I h I. im pr.r iws 41tIMU..IlsiIS 4iMaias&* 1. adi OWL S. t .C1lpumhd boam abioi 3Wm Is gwi* 7. 38" o,i s øIj jjj ;•e*4iwm ?t 3 4& JiS* ?3n411g P.O. Box 341 0asi4a, CA 92049 17601 131.7AAA .... f7.1mi1 Attachment 12 10116 W23003 APPENDIXH Estimated 0 & M Costs for BMP Project Estimated visual derived from Cimns Pilot aMP Study. This spreadsheet alt ____________ -Labor Equipment MObelalI Total ditangs as additional data becomes available. Per. Mrs Rate Cost Type Days rate Cost item cost Coin UIOFlLTER — STRIPS and SWALES Prevend"MaIntow arid Rouiin.Inipedlans MAINTENANCE FIELD MEASUREMENT MAINTENANCE suE-spEciFic ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS . AveragevSgutstiofl I I string hulajflexosede12 Once chi" wet I . • Indies. emerganos of Visual Inspection of aeseon. onos duting Crd vegetation to On i rake. fork. bees. or woody vegetation Vvcuojlot* dry I (dpending average height oil Rsniese any trees, or one-ton buck a; bags. safety Noigrs of egetallon veatslk.n stitPfsweie onWDei) Indies woo wel5ll.... __j0l 4383 436.3 hydroseeder j 21 2684 53.68 equipment so 539.98 Vls&mlinapedilOflcf i stilpllwsle. Prepmea aftesdiematicto and distrthtillOncfbwlen I Less Own 90 percent or browning spots to . coverage In strip be restored. File the Assess quwatty - InvsrVswaIe or less than sduematic for r needed In May each Assess adequate vegetative 70 percent on swell assessment of year late wet season Reseedlrevugetate . . one-ton trui & cover aide slope patsistunt problems, and lo dry season, barren spots by Nov. 8, 43.63 349.04 hy&vseeder It 48.15 48.15 seed 150 547.19 Scarifyareatobe restored.toa depth of2- k,cties. Rest" elda : slope coverage with one-ton trude & hydi-oseedmlxtws. ohydioseeder 01 26.84,1___p ._L. If after 2.ppllcabons (2 . seasons) of and slow"Iia I urmicaussful both trum .n erosion bla'*etCr equivalent protection will be Installed over eroding one-ton budi 6 areas 0 43.63 0 hydroseeder 0 0 0 During routine bashing, Remove Stier, and orie-eti budi& Inapeot for detrfla acwnwdatiOfl 0ebfle or litter present Visual observation par Districtsadiedule. debris. Non. 0 0 0 hydroseeder 0 0 0 0 Removesedimertif flow Is d 0. detemilracauaewid I I take corredveaction. If . sedment becomes deep enough to diange the flow graderit, remove Sediment at or now sediment during dry vegetation Mi^ season. dv,rn.4al1aand : d-isnnellng of flow, property dispose of seed, testing: Irieped for aecumutated Inhibited flow due to sediment. and & I . hydroseeder :1 48.15:48.1501 46.11511= -- disposal: =1 once every sedimint diange In slope. Visual cremation Annually revugetote. 16_43.83:898.08 104823 three years 2 OS 18 1523/2003 APPENDIXH Estimated 0 & MCosts for BMP Project• Eshmeted vlaues deilved from Catfruns Pilot BMP Study. Tile spmadtheet alt I Labor - Equipment Materials Total dmW as addidonal data becomes available. Per. Mrs Rate Coat Comments Type I Dan I rate cost Item cost cost Nod .nghieefto necessary- If neueY. m0adetodssi1 specification Send I revs . If I Is an process Mmuld IM In M". Revagetate shtpi'swals In Nov. Twgst I COE eUon prior to wet None 2 43.831 87.26 0 87.26 Arwatty and altar em Inetoos cLot. leepage. et054St w4 OtLdefl hudi & Ineped for burrows BI2T5, bcls5 mounds Visual ohisitvedofl vegetation trlmnft tadeegu. bediM fomly. 0 0 0 Iydtseeder 0 2684 0 0 Ir structures. oudut structures. alduulcpe3 or ofier features deinaged, ulgndlcall Corrective action prior to eroslcn.em.rgancsof Se.Anri&otuly, Into wet aessen Consult If Immedhit. Remove trans, one-ton buck & eneal Mahlerwnce ones, woody vegetation wet season and late dry enginaur an any or & solution Is not evident woody veguudott 16 42.631 898.08 hy'oseedit j 26.84. 53.88 751.76 TOTAL 610 ALTER AND SWALES 52: l2258.76 203.66 . 500 2972.42 610 STRIP WITh SPREADER IfldUd5$ at the shove DITCH plot thefofloslng. 0 0 0 D.ster the spreader ditthtoe depth Ofless I than 0.25 bxties. If sediment Inipecles the da waudngsodvitthan man or rentove VM WIt/n 72 hours after a portion of ft seotmert . tsr ecaJmUtadon In Standing water In alarm event 0.75 Ctweotaltze and I 3: 43.63!130.89 Inspect for starx" water spreader ditch spreinderdltdi Ind iessrgreater. _ _j_89 -- De.waterthe spreader dam toadepthofless Van 025 yremoving ! thabypasaphigtold slowIng the water to drain bft UdItrafion Ifench. Use cam to — sediment from disdwglng Into tiw WifUaIlnVencIt Ruplsoethebypssaplug once the de.wataiing has beenomopluted. . 8 43.83. 281.78 0 0 & 0 281.78 30116 11 flAIA f, f. T.... -- -a. n— APPENDIXH Estimated 0 & M Costs for BMP Project Edmaled vtaov ved from Cdowis PEal BMP Stip. TIat apmedulwet wit Labor Equipment Materials Total remmente changeasadclill'rwi date becomes available. Per. Mrt Rate Coat Type 'Day ret. Cost Item Cost Cost At the end of the wet seasom remove the uplug and ato. the spooft ditch to &uittU5eOWeto prevent sediment from . . disdtwgthg Into the inowslon . I Remove6 dw.ctwise. end dispose of sediment . I from to - ditch. I I Replace the bypass plug bofoiw at. beginning of dIs e'a wet e.uon. 2 43.03' 8720 sedan 1! 21.28 21.28 oasis 200 308.54 TOTAL 00 STRIP WITH I 7-1 SPREADER DITCH 551 - 2399.6 208.60 SD 3103.31 40NEROUSDEFLECTWE sSPARA1oN(cos)uNrrs Preventive Md,floiwetoe and . Routine Inspections DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFiC ROUTINE AC10NS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS I inspect sump for acaJ1ntdadOfl or of Will. I • Wen the sump ls50% full doing two osrweoutive - ktspadlons. ______________ _______________ ______________ — .................. _________ 0 -- -- or testing & Annually In May, effect donning within 15 days "PY ........___! 43.03 3141.36 - a V5dor 1 3. 198.75*1 598.28 disposal I coJis IBM 5537.01 .0__— 0 _ I i Hours Remove blat and delete accounted for Inspect we bos for Pfesen08 of fresh and Modify doing the wet while cnsho conducting doIng eooamzlathonofMaterial. debris Visual Observation sesson Inspection. 0' 01 0i 0 • : 0 0kt5peCbons If edodog water carnal be removed or remains Inspect for stendlng water. ( Annuity. 72 hours sitar through ate wet eeaacn Inths1a with all of bwpedlon) Sheiding water In sump Visual observation — begect storm (0.75 In) rituf VCD. None • Hours Inspect th screen for damsge Screen becomes . insourfted for and to ensure that It Is property dogged. damaged or Annually before wet . dIdfl featanet loose Visual observation season. Clean screen. None 01 0. 0 0 0. ca a o inspectiong Immediately conwdtwith engineerond manufachows I rvStDd5Vda9 Hours Holes In screen. large a osrise of action. effect accounted for doris. damage to Annuity or after a repairs prior to the wet I I during Inspection for atiuthtal Integrity housing or weir box IVIsual observation damiosil. season. None - . CDS UNITS F io.TOTAL DRAIN INLET INSERTS — _________ FOSSiL ALTER 4 01`15 12312003 APPENDIX H Estimated 0 & M Costs for BMP IICUUV4...,, ....SLlUI!5 Project Eeitmated vtauea derived from Cdasors Pilot BMP Study. Tide spreedsheetwlit Labor Egelpmur* Materials Tom r'.ommj thengs as addiboral dats becomes available. Par. 14,, Rats Cost Type Dan ,ft cost flam cost Cost Preventive Maintenance and Rcraine Inspections DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC ROUTINE ACTIONS INDICATOR SuWdient debn~ that torrid interfere with MEASUREMENT FREQUENCY ACTPATY REQUIREMENTS proper fravetonlng of Inspect for defrflaJath Insert Visual observation During th, wet season: 43.83 . o 0 Remove and pr-arty To" completion period = Before and once draing each White onsite conducthV IargeO stone (0.25 In) OVant inspsddort 18 43.631 785.34 0 785.34 Replace Fossil FftwTM adscrbmntwlthtnlo Absorbent granules dark 0 At tho end of each property dispose spent gray, or dalter. or unit targeot storm (0.25 In) media prior to wet 08 and grease removal dogged with sediment. Visual observation event esasoit 2 43.83 87.28 - 0 87.28 Replace Insert or - coftuu* vendor to develop course Broken or otherwise Twice per year In of eaton. silent repairs Inspection for sauaurul kftgft damaged b-are Visual observation October and May. aidiinlowarldrVdap Non. _2i 43.83 87.26 0 87.28 new and property dispose of adsorbent; and lauting End of wet season, April media a Replace medla & disposal of msdrwe 30 None AUy. In May before Oct I None 2 4363 87.28 sedan I 1 21.28,21.28 costa i 115 223.54 - TOTAL DRAIN INI.ET Fit 24 . 1047.12 21.28 115 1163.4 - DRAIN INLET INSERT SnW-" GUAM Preventive Maintenanceand Rltp.cllon$ DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Visual inspection of RepI Insert Target Sedlawntmorethan- sediment collected Sediment removal inthea within Insert During the wet eeascn: onrdladlng i 0 . 0 0 Remove and dispose cf I Sufltdem dsbntsftash detntslfruait. Target I 87.28-1 that todd Interfere with iaddarIng o completion period white proper omita condiclag Inspedifordetutsikesh Insert Vlsualobservetion Otngthewetseascn poatOn. 0 ' 0 Wien cit absorbent Visual observation (absorbent polymer 'Atitrin lOworiring days. I I polymer becomes expansionhidlostes an replace oil absorbent and grease removal satiratad with oil saturation) Morlidy polymer 2: 4&6311 87.26 -- Replace liwertor 1------ -".- Inimediately consul vendortodavulop. I . course ofaaton, efledi Signs of rips, gashes. Twice per year In rape!, withIn 10 working S inspeddon for stIuthrai Integrity endlorfeiten media Visual observation Ontatur and May. days Non. 2;- 43.83: 8725 * 0 - - - 5 of 16 f23r23 APPENDIXH Estimated 0 & M Costs for BMP 1W! IICI1I1UIJt Cfllfl.A!WIflWfl Project Estimated stases divsd from Cat(fwss P801 BMP Study. ntis spreadsheet will - Labor E**myt Materials Total Comments cit ass addillonal date becomes avaIlable. Per. Mn! Rate Cast Type oars rate cost Item cost cost now Remove cherecturts., adsorbent and FoPly dispose of and testing End of eat seamM frqsli me". Replace media . & disposal Artraudno of nodhmn 30 None AAJItddIy. In May before 0011 None 2 43.63 87.28 sedan i 21.28 21.28 costa ios 3.s4 TOTAL ORAININLET INSTS.STREAM GUARDS 6 201.78 21.29 195 478.08 EXTENDED DETENTION . BASINS Preventive Maintenance and . I OESIGNCRITERIA, MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Cut vegstaticntoen Average vegetation Visual observation end average sigirt at8- . gieatarRan12- random kidieasndremove t,immer. Basin side - planted far Inches, emergence of maaeaemvdo Once dotIng wet b*nmbigs. Remove any i : . fork erosion got and planted (fees or woody througit CIA the side season, once during bees, or woody : bags, safety: Invent vegetation, slope ema dry season. vei.tatwt. 481 43.63 209424 one-tan budi 2:. 26.84: 53.08 one-n.m ascii I equipment so 2197.92 Rssasdase bsnen spots prior to wet Slope atebuity Esldencsotenoslon Visiat observation October each year season. 0 43.63 0 hydioseeder 0 48.15 0 seed 150 150 Corded .nvlronm,ntul or landscape architect for appropriate seed mix. (falter two app8ceborte (2 seasons) of andpowd Is unsusaM bath bates, an erosion blanket or be beaded aver erodstg areas. No erosion blanketed its I tlud In NOT AN ANNUAL ft basin invent. COST 0 43.63 0 One-ten tuck 0 28.84 0 blanket 0 0 Annually, 72 hoils Standing water for mom altars tergeSl storm InspectforsteroMng water. den 72 hours Visual observation (0.75(n) avert Drain foobty None - chadiaratatdag ShoitidbeAsvnarl - orifice. Mies. Notify engineer. it immediate solution Is not nflng rosatne (feelting. Remove and dispose of ImMcdonferiyasherlf debris Detils#trash present Visual observation per Districts adraOjle. trash and debris None : Measur, depth at 4-yd dump apparent martinualt b'.di, badthoe Inspeddon for sediment and minImum & trader, one- ,..g&nstfl and Sediment depth awamtiation of Remove and property ton tuck & of sediment for exceeds matter on staff sediment. Calcolate dispose of sediment. hydroseederse taa'ing and oiW!.c every 5 removal page average depth Annuafy Regradednecessaty. 1843.83698.08 dan 0.4170.510.8 disposal 460 1228.68 years - 80118 112312003 APPENDIX H Estimated Project Estimated 0 & M Costs for BMP viattes derived hot.. Calkerns Pilot BMP Study. This swedtheet*st Labor Equipment Matanais Total ammente thonge as additional data becomes availed.. Per. Mrs; Rate : Cost Type Days isle cost Item Cost Cost - and altar letters bjasws cause seepage. erosion and Inspect for bIflTØeg Iltunvirs, holes. mounds Visual observation iti1I.obtom*t9 Iealwge. bad" firmly. Inlet structures. outlet strudures. side slop" or all torfesturss I damaged. significant siosim emergence of bees or woody COITeCbVe edaist prior to vegeidan. graffiti or SemMsvtuslly. late wet set aessers. Consult General Meirthinos vandeft, fenos season and late thy engineers if 5te Inspeddon damage, etc. Visual observation season Monthly eckalon Is not evident. None 18 one-ton buck 2 28.84: sasa 75175 TOTAL EXTENDED BASIN ad 34904 17795 860 4328.38 INFILTRATION BASINS Preventise Maintenance and I ROAM tnspeddons DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Visual observation and Cot vegetation to on Vegetation heightmndom average height sf6- . exoseds 12 isthee. muasuremsate Coos during wet lndhes. Remove any . nake. ftk Vegetation of basin Inv an emergunos 01 bees or ilvough out the side season. once dinIng trees. or woody . bags safety woody vegeon slope and invert wee dry season. vegetation None 481 4383 2094.24 1 two,-ton truck 2. 501 100 elpJlpnhaflt 50 2244.24 Annually. 72 hours slier Standing water for more a tatge storm (0.75 : Drain facility. it Insped for standing water. Own 72 how, Vierel observetlon In) event possIble. 1Wi 43.63 590.09 Remove sediment one-ton Suck 4, 26.84 101.35 505.44 cavers under c Notify engineer to consider acsflfy invert. and : . I Sediment agradeItnecessary. - 0 0 0 removal If unable toadtleve . I acceptable rate wboplemam alternative idution then move to daosmrnlsston o 0 -. 0 Zlfeterhdlngwstorcer% not be removed than nodtyVCO. None nipecbon for bash and debits OwIng routine bashing, Remove and dispose of at inlet souctures Debndtrash present Visual observation per Districts soltedide. Sash and debits None 4-yd dump Measure depth at appealS maximum tnick, loader & I and minimum Remove, thamoterbie bailer, glider. I Sediment depth accumulation of and P°P'Y dispose 01 sedan. one-ton ppckon for sediment exoseds matter on stall sede.Jtt CaJslte sediment Raged. and truck & seed. ta3bng once every 10 rcmtuiotion gap. evg.dupth Annually revegetate bare areas. Now 41 43,631 174.52 h*oseeder 1 0.51 2.94 12841 & disposal iso 452.99 yearsR.s.edfrevegetate barren apotsbyNov. Smelly surface If . CIte-ton Suck & siopeetsistity Evidence oferoslon. Visual observation Oclobareadtyear. needed. 20 43.63: 872.6 d,oase 1: 48.15. 48.15 seed 215 1195.75 APPENDIX H Estimated O& M Costs for BMP I runc, . .4II5 Project Estimated slsuas delved from Cubans Pilot BMP Study. This spre.dehaet will Labor Equlpmas* Materials Toed Comments thange as additional data bloom., available. Per. Hrs I Rate • Cost Type Days rate Cost Item Cost Cost If after two epØostlona (25u0n5) of and Wneth Is unauosussfal both times. an blanket or • equivalent protection wts be indelled OYUretOdifl9 areas. No erosion blanket will be Installed in the basin Invert 0 43.83 0 One-ton thldi 0 28.84 0 blanket 80 60 Contecat .n*onme,ad criprposca eedetectfor seed mix. None 0 43.83 0 0 0 Annually and after tere bitr, cause saape erosion and Inspect for burrom 8&sys. holes, mounds. Vjtijal observation vegetetiOn tlifllfltlr4 Ieakage b.di95 firmly. None 0 43.63 0 One-ton Mick 0 28.84 0 0 Inlet structures. oullet structures. side slopes or other features dwnaged.slgfll$carl erosion. Tal'. action or vvoody prior to wet sessoit vgllaion. Waite or Sami.Amusdy. late Colasit engineer if onaai unem. van&m tenos wet season and late dry immediate sctralon Is not I I Inspeddon damege etc. Visual observation season evident None 20 43.8& 872.8 twa-ton buds 1 501 so 922.8 TOTAL INFILTRATION BASIN 101 - : 43398 51181.021 INFILTMTION TRENCHES 535 Plevenlive mob FM and Routlnalnspectlons DESIGN CRITERIA. IIAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC . ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Anety.72hows I Inspect for stending water Slondlrtg surface water for more in 72 hours - Visual otiaervation after a target2 storm (0.75 in) eyed = Drain teOltity Notify engineer to 18. 4363 89808 . . One-1011 bud1 2; 26.84 53.68 751.78 - ooie1der 0 43.63 0 - -- 0 Undertake Investigation tiwestigabon for course OfddO adVev ----- Iebtelofation rate. if unable to .cttiwe - foedon den6MPoperations . :--------0 -------............0.._._ not be removed. notify If standing water can ; Does not Include Ve lor VCD. None ! : 0 . o : a Agency Costs Irepedson for basis and detail Duflng routine frerislng Remove and depose of at Inlet and omalet sbuc*uses lraslssteb,is present Visual observation per Dlsbide adsedele. bash and debris. None 0 43.63 0 0 0 n 8of 16 3a003 APPENDIX H Estimated 0 & M Costs for BMP Project Estinsuladvitumdehued from Catbana Pit. BMP Study. The apreadalwit otU - Labor Equipment Materials Toted Cn,nts drange as additional date becomes avatietee. Per.Nrsf Rat, Coat Typo Days . rats Coat item Coat Coat Viauaiinspet.onol the atone aggregate Rumovu top layer cf no sediment ehorid be Sundit alit. law It S vWMeatthetopol'the and atone. wash stone trendit due to and tuinstat fabric atat gradeat replacement: t.forsedimeri sordbulhdupfr-m atone Iriobinch prior to : stai 10-yd j atone arat Once every 15 remenulatfon Visible sediment flutetfabric. AmoatitY. WSt5O5SOfl. None ei 43.83: 349.04 dratipitudur 0.088 6000 396 fifterfabric 1200 1945.04 yeah abut.aee. ilterfabuic or cow teatfoesdameged, Take corrective ediIor emergence of bees or prior to wet season. woody velJo. 1prIam Sen,l.Annudiy, late wet Coreril engineer If No Remove any General Maintenance greffib or vandalism, season end lets dry, Immediate eoMion Is net bees, or woody Inspection . lance damage. etc. Visual observation seasonMon" evident b0111&,fl. 8 43.83 349.04 one-ton buck 2 26.84' 5188 . 402.721 TOTAL INFILTRATION INCHES _________________ 321 1396.16 503.38 1200 3099.52 MEDIA PLREOUTE sventiv.MdadinwrCelIal Roudnelnspeddons ---.---------•h----------- DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCESITE-SPECIFlC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTiVITY REQUIREMENTS 0 4&63 0 One-ton buck 0 26.84 0 lnspe 'for sedunwM Sediment oomlas10% eonanulatlon In pretreatment edbnentetion drwnber of the litter chamber vattens. . Measure with eporewial device Amuaiy In May. _____________ ____________ 4! 4163 174.52 one-tm budi 1. 2684 26.84 201.38 Remove sedhtierdpew - to wet season. I i . t. I and property dispose None Si 43.63,349.04 sedan 1. 21.28, 21.28 costs 600 970.32 0 : a Olsen per njeduior'a Permadaae'a gutoetnes. Prior towet Inspect for minor maintenance guidelines None Arvua9y season. None. 41 43.63 _i!i one-ton buck I 26.84 28.84 201.36 I . I Cortudi with need for replacement of I If msadacbxer cendne@ replace cardstals. . • Prior towetsesson. I encedatahers I I to mwsasesJrer to II . major Menufddurehs recommended Per manufacture's Per MW how None reITIaIntIg I malntenanc • : By Contract major maintenance of 00 meet_a Oj 4163 349.04 one-ton 1 2111.84i 28.84 5000 5375.88 and avenue Remove and depose of Inopeckon for beth and debris bath and debris when on at inlet and oubat sbuctursa and During roatins bashing, site conducting within vault. Tnaslsldebiis present Visual observation per 0158188 aderdule. Inspections. Non, 0 43.83 0 0 0 tsr accumulation in Standing water In any any stfucktra, or other abudeow or other Ancually, at end of wet Gravity drain where Inspect for atending water locallonwiddi ft2W location wWtIntheftItsr aesson. posslbis. 0 4363 0 one-tonatat' 1 0 0 0 9 of 16 2312003 APPENDIX H Estimated 0 & M Costs for BMP Project Etretod elsues derived from calbw%s P9di ftMP Stialy. 1145 spreadsheet MU ______________ _____________ . _______ _____________ ______ _____________ Labor EJpmSf4 Materials Totol Comments d=W as adeiXnM date become, avallatee. per. Hrs Rats Cost Type Days rate Coat Item Cast Cost • = It am" water can : , not • net be removed or • Inctuda Vector remains Ovough wet • Confrol season notify VCD. None 0 0 Agency costs Inlet abuotures, oqMst Take wvedlve edion abudwes. verdI. piping, prior to wet semen. or cater features SemlAnnuady. late wet Consult engineer If Canoed Melntenance damaged and for gifts semen and lets dry Immediate scbdiwi is not if, -'I or vendatlam Visual observation season Monthly evident None 8 43-631 349.04 on,40n buds 2; 25.84 5368 43972 uOTALMWtA FILTERS - PERLUTE 32' — 1398.16 _j8 5600 7151.64 MEDIA FILTERS —SAW WIPUMP Preventive Maintenance and Routine inspections DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE . SrTESPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Annuft, after am I tariledsoxm (0 75 In) Drain tim, exceeds 72 Oetemrina dratn time event dering Remove sediment. Drain time of 48 Itcits hours by visual observation season bash and debrIs. 4 3 174.52 one4cn buds 1 3954 201.26 • _____________ clredcodulco 0 0 • 0 :Ndifyenglnaerto 1 I drums. shovif.rake. cortsioler...oving fop 2 . j dAIM Inches of media and 9 3'* • dispose, alsediinent : : asnftned Restore media depth to . space lebrdteswften oval al Escondido MS . equipment media depth drops to 12 Delaweru SF — Remove i characterize Indies. Complete prior to end restore media ition -- wet aassClt depth 1o12 Indies. 12! 4383 523.58 boom bUdS 0.5: . 1250 1811.03 very2 years drums,,: • shovel. rskej dNm conlined space Remove sediment prior equipment Irwpectforsediment Sediment depth towetseason. I _ _ aomrmulation is sedimentation exceeds marker on toft Messrs. with Messrs. sediment Clk..om ltz. sediment . ; booni .and disposal izso atiamser de depth mmnuady. end property dispose. 12 43.83: 523.56 buds 0.5 74.94 37.47 1611.03 every 2 years Remove and dispose ot . confined Trash and debris Owing routine Noft bash and debris during space Inspection for bash! debris present VIsual observation per Districts sdiediile. routine bseh1n4 None 0 43.63 0 0n54or1 buds 0 2684 0 equipment 0 0 Mater assessment 10 . dutamilna if problem Is elsdrlcif or m.Jtokal. coretneti Ins ped pumps for proper EnergIze pump to see Take 9,action, space ferroboning Pomp does not operate If water Is dieclasged After every stormReplace pump If needed. Distinct? Utter, only 0 4363 alone -ton truck 0 2684 0 equIpment al 0 10 of 16 Ia3t2000 APPENDIX H Estimated 0 & M Costs for BMP Project Estimated siauss dSI1VOd from CatENts Plot BMP Study. This aproadeheet edl dtwig. as additional data awavable, ______________ _____________ __________________ E%dp— Materials Total lCormmme Per. Nra i Rate Coat TYPO Days; rate Can Item o Cost Cost pimip or Wispect pumps for ersbosablllty Per memgecbte'e Per manidsssa Per mawfadsse's Per mentdedstes cova space and periodic mairdenartce guidelines guidelines guidelines gr4deflnes District 7 filters only 0 55.7 0 one.tcn DoCk 0 2884 0 equipment 0 0 alter veplatiort -, seepameisi arsi Inspedi for buns Brtreas. holes. mounds. VIsual observation utmmin Issiregk baddlil fruity. None - 0 SWift vroterinarryArmft.'M hates sitar • any aDocbare or other atntcbse or deter a 1rge12 eterm (0.75 Gravity drain where Irepedi for stonding water location witlln Tue filter location widen the Ifiter In) possible. _4 43.63 174.52 cra4m truck 1: 2684 26.84 20138 Nolifyenqkueer.W krWAWFAIS schAlon Is not evident _2i 43.83. 87.24 ...............i 87.24 if hmfi Water . : Does not • not be removed or trx*jft vector remelus through wet . season no* VCD. Nan. 2 43.83 81.24 . _0 87.26 Agency costs blat structures, outlet strudsjres.flIter fabric or I other raatur.sdsmaged. VAIIM30wakhig days. emergence of tat'e corrective action. I vegetedm gralfill or Sesnl.Asmuaty. late wet Consult engineer If I I General Mé0.. vendelam. lence esuon and late dry Immediate salullon Is not I Irupoteon demaIM etc. Viartol observation season Monthly evident. None 81 43.831 349.041orm-Untruck _2: 25.841 53,081 • 402.72 TOYA—L FILT-SAND -- WIPUMP _2 13 2500 4602.02 MEDIA FILTERS-SAND WOIPUMP Preventive Matmenoruc. wtd RoubmInspeclions DESIGN CRITERIA. MAINTENANCE FIELD MEASUREMENT MAINTENANCE SITE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS A,muatg after ane begeat sew nn(0.75in) Dtsln time exceeds 72 Delemulne disin time event during wet S Remove sediment. Grain time of 48 hOurs liOI5 by visual observation season bash end debits. 4 43.0 174.52 01e48fl bud, 1 ii 28.844 28.84 201.36 Chedtoflfic. T0 drums. Notify engIneer 10 sime. rat'. consider removIng 1092 j titian Inches of meats and grappler. I dispose of sediment. confined Restore media depth to I apace I 18indueswfuenoverati EscendidoMS equipment I meats depth drops 1o12 Delaware SF - Remove I dexdiertsa Indies. Complete prior to arid restore media : Don and wet season, depth to 12 Indies. fr 43.63 349.04 boom budi 0.33 74.94, 24.7302 disposal 5341 1206.77 .vey 3 years 10 110118 APPENDIX H Estimated 0 & M Costs for BMP Project Estimated vilues derived from Cannons Pilot BUP Study. This spreadsheet wit Lobor Equipment Materials Total Comments duelge as additional data becomes available. Per. Mrs Rats Coat Type Days rate Cost Item Cost Cost I drunm shoveralw. drum greppier. rmdined I . $pace Remove sedenent prior : . equipment Inspect for sediment Sediment depth 10 Wet sassOft : thaiacteilza accumulation In sJmenlatlon exceeds matter on staff Measure with measure sediment Clrw.dieiioe sediment ion and -- appropriate device depth dlape5. 8' 43.63: 349.0.' boom buds 0.33; 24.7302 disposal 833 : 1208.17 levM 3 years Remove and dispose of conth Trash and debris During routine aashln0. Ish and debris dining . ! space 1150.81 Irapeobon or essiri debris present Visual vat1cn p Disbicte schdi4. routine banhing. None 24 43.83: 1047.12 one-ton buck 2! 28.84 53.88 nquipmant 50 Annual Inspections after Win,e burrows emma Inspect for branD.. Bismea. holes, mounds. visual observation blmmin leakage, badiot firmly. None - , 0 0 0 Water accumulation In Standing water in any Annually. 72 hours alter any 59uctar5 or other structure or other a tazget2 storm (0.75 Gravity drain wtere Inapectfarshmos w.tar locaiton wuitin the Iliter location wllisn the litter in) possible. 4 43.63, 174.52 one-ton buds . 1' 26.841 26.84 201.38 r Notify engineer. d I I Inunedi_ata aokation is not I evident 2 43.63: 87.28 : 0 87.28 I Does not not bemovedor . ! . . Include vector remains If wet . ,Contnol seascnnodfyVC0. None 243.83 87.28 .0 . 87 costs Inlet structure.. outist . structures. liuter fabric or other features di.mavd, j55 emergence of how ,..i.e action. vegaadn grsllltl or Semi-Annually, let. eat Consult engineer it General Maintenance vandalism, fence season and lit. dry Immediate solution Is not Inspection damage. etc. Visual observation season Monthly evident . Non. 8! 43.63 349.04 one-ton buck 2 2&a4i 53.68 402-72 TOTAL M4A FILTER-SAND i. V.JPUMP 8O - 2811.6 210.5 1710 4544.3 MULTI-cHAMBER TREATMENT TRAINS Preventive Maintenance end ! Routkwlns#ections DESlQCRIA MAINTENANCE FIELD MEASUREMENT MAINTENANCE .lTE-SPECIFIC - -- ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Drain dme Walker than 72 hOurs or sediment . accumulation Is greater Maximum Idler drain time 0172 then 0.1 inth over more Mar one targsQ storm fire for design and smaller than 50 patent aid* (0.75 In) event dining Z Remove and replace . . . surface area. Visual observation wet season, filter fabric blanket 4 43.63; 174.52 one-ton truck 1 28.84 28.84 . 201.38 : If empersists. : I cenorot with engineer, I the made may need to be replaced .Complat. prior to wet season. Non. 21 43.63 81.28 : 0. 0. 0 0 87.28 11 ,12o118 .12312008 APPENDIX H Estimated 0 & M Costs for BMP Project Eatimatod etares derived hol,CatWmpfteMPSoidy.TK%SPMad~VdI Labor EquIpment Mate,tels lObe Comments dverge as addidonel data becomes available. Per. Hr. Rate Coat Type Days rate Cost Item Cost speeft for trseN debits at .OUInQ rurabre Remove and dispose of Cost I, cenitned Inlet and olatat eliudaiss and Trash and debris freat*rg per Disbtct trash arid debits DinIng SPOCID at. uci-r . prevent Visual observation soltedide msalne treslrtns. None 0 43.63 0 one-ten ft"0 26.04 0 equipment • 50 50 _________ dVWTIS. shovel. rake.: • grappler.! omrimed I Sedbnentacolinuiates -. of the . Remove eedonwrt prior apace equipment underneath the tube Remove lists seat er, less to wet on.characterize ItwpeotICn for sediment .eblers Maximum 012- Measure with measure aedlment Ch.1at1 aetilmeil . -nd asinutabon bet grIt chamber .puplete device tiepat eimiaIy and properly dispo... p4 36 43.63 1570.68 one-ton truck 1 25.84. 28.84 duipeaal 800 219752 c If atendb Water Can . : . not not be removed or * . Include Vector remaIns through the wet season nobly VC0. None 21 43.63! 87.20 0 . 67.20 Agency cost. Remove and ,spl.Ce . confined SPOOR eqmant. Reptare filter, media every S years per designer's OperatIon greater then 3 fitter, media. Ch...rIsi and I vector and one- . i cheracterbta bon and specification year. Not applicable Every 3 years properly dispose. Noire 81 _3 349.04 ton trnabi 0.33 198.75i 655875 diSPOSal 1200 1814.0211 every three ye neeaoibent p..orhnmediateilylf pillm we darkened by Inspect scibeM p8ev. In main seftq dlTb Darkened by city Visual Observation Annually. In May. cOy malarIal, dteabe&. end properly dispose. None i 43.83j 174.52 one-ton truck 1 28.841 26.84 sorbent pillow 100 301.35 Make assessment to detam*Ie If problem Is electrical or mechanical. . Inspect pumps far proper Energize pump to we Take approprIate adhon. Iipece Pump does not operate If water I. diadnarged Alter every storm. Rspl.ce pump If needed. None 0 43.83 0 one-ton truck 0 26.84 0 equipment 0 confirwd 0 Inspect pumps for serviceability Per meradedaxa's Per msnicture'$ Per manideduree Per menufeoturs's epece, pump or. and periodic maintenance guidelines guidelines guidelines guidelines None 0 557 0 one-ton truck 0 2684 0 patto o 0 Irdetatrudeaes,olalet etrudanes, filter fabric, ! settong tubes orother . tealiresdamaged. Wdiln 30 WOil1Ingdays, emergence 01 bela coffective adorn. I vegetation. gralhltl or Seml-Amual)y. IMA wet Consist engineer If I General Maintenance vandalism, tonce damage, ito. Visual observation season and Into dry season immediate solution Is net evident None _81 43.63 349.04 one-ton truck 2' 25.841 53.68 Inspection TOTAL MULTI-~MEIER TREATMENT TRAINS -, 199.788 I 1950 4942.108 OILWATER SEPARATOR Preventive Mainteflince end Routine Inspections 1 1 DESIGN CRITERIA, _____________ MAINTENANCE FiELD aIEASUREMENT MAINTENANCE JIVE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS - .1 12 13 of 16 h23003 APPENDIX H Estimated 0 & M Costs for BMP Project Estimated Matte, derived from CalOans FIlet OMP Study. This spreadsheet will Labor Equipment Materials Total Comments thonge as additional data becomes available. per. Rate East Typo Days • rate Cost Item Cost cost Inspect for sediment Prior to wet seascr% eonimulailOr In the pie - Ma material. Characterize : tes*V and chember Greater than 12-irtes appropriate device Atuaddly and properly dispose. None _4 174.52 0 etspoaei 120 204.52 every 5 years br towet season On depth is not more Gaige the level of remove and properly • Inspoot for dii eosatuieliofl In than 50 percent of ailMeter with a dispose of oil and I .testing and of thettiber chamber volume wooden gauge aMA Annually pmase. None _l 43.63: 43.83 0 disposi 60 103.63 every S years Wash the coalescar In an eppropilatssioswith at.er for debits and Debris or gummy saure hot ws I gjiuny deposits deposits present Visual observation Atusally When needed. None _1 43.63 43.83 0 . 43.83 Fill with Water prior to wet Inspect water level in tonic Less than full Visual obetvatlon Anniddly aeseon None 1 43.63 j 43.83 I 0 43.83 Operate mechanical e-var-d toensct.ptcpsr . Inspect far general mechanical Per manufacture's Per manufaderres operation. Repair as IntegrIty guidelines guidelines Annually needed None 41 43.63. 174.52 0 174.S21 TOTAL Olk-WAIEP • SEPARATOR ii 479.03 0 180 859.03 WET BASIN Preventive Maintenance and Routine Inspections ..--..- )ESIGN CRITERI& MAINTENANCE FIELD MEASUREMENT MAINTENANCE $ITE-SPECIFIC ROUTINE ACTIONS INDICATOR MEASUREMENT FREQUENCY ACTIVITY REQUIREMENTS Evaluate drain time from Inlet and cutlet flow data Cggers or Once during; wet 24-itou draw down measured observe 25 hours after season and alter between the rim of the outlet DnewdoMgiMAer than targe12 sborot (0.75 In) osrepledon or I stiuderm teat Invert of the VVQ 25 hours or water Is Observation of water modiAcetior of the orifIce In the outlet stiucture. Rowing over weir. flowing over splitway fadley. If 45.hosis: 443.63174.52 One-ton truck 1:28.84_26.84 201.35 Open gets, to dlathargewatetto I peimenentpod : elevatIon. 243.63:87.26 one-ton tnadi 1 26.84_2t84 • 114.1 -__-.----- I r----I :Clear outlet of debits. 21 43.6387.26 one-ton tittdii I_i I•__4_26.84 114.1 :Consiatenglneerll I needed. 9 43.63_87.26 Ofle-tOfl Vudi i 1_26.8426.84 0 1 . 0 0 If water is spMft over w open caud gate until water levellset I Pod el.vatlon. Citedeer I outlet ofdebris. None 4 43.63_174.52 One-tOn tiudi 1 26.841 28.84 201.38 UnetIIy and VWme burrows cam erosion and I Inspect for burrows Burrows.holes,mouride vis•ai observation vegetation trimmin& lesitoge.bacldtl firmly. None 41 43.83i 174.52 one-ton buck .1_28.84!26.84 201.38 side stops. Taiw corrective action, or or other features rest" to as-constructed • 1 ition piortowet erosion. gre03 or Semi-Annually. late wet season. Consult I General Maintenance ,alaIl.o fance season and late dry 1co, e.j..... if immediate Iropecton - dernaM etc. visuai otiseivation season solution Ia not evident. None 4363'349.04 one -ton budi _2_26.84_53.68 402.72 13 1 1401`16 1r232003 APPENDIX H Estimated 0 & M Costsfor BMP Project Edmated Ottotes derived from Celfrens Pilot BMP Slim. Tide sprandAimt wig ______________ _______________ ______________ Labor - Equipment - Materials lobe O1Tho$1tJ domge as additional data beosmes availatao Rate Can Type Days rate Cost Item Cost Cost inpeet Zone l4 for sleetdon 0 • W.5Q5 and density tOSibefl vector abater m efficacy 0 • 0 - "an a blabow Rinift the Vial Basin to datamdne if any birds are, raftqorcthsfsensitive animals eta preset If Visual. visible birds arendmalth vagetaft growth or advice from ON (See alladvnuils for wre Observable vegetation emergent itatisn proceed with me osvwofdensity WO56I 81 70 561 'redan 1 21.28: 21.28 581.28 2.LoaerandmaN,laln the water level to stposs ft am lo be nslntabtod. do not osniploteJy, draln basin 4 43.81 174.52 one-ton Mdi 1 26844 2884 201.38 airing I - heal bags. so" Msdtanlcally remove ailcutpswosvagedron 43.631 ..! one-ton - 80.52 100 2623.8 Dispose of the nuft In a Me krdffi or other safety appropriatedisposal anm I .qulPment 24 4363 104712 Packer 3j 53A4 160 50 -- 1257.44 4.8. ReMade mosquito Ill as recommended by vrceitelagency. None 8. 701 560 sedan . 21.28! 2128 58128 Mosquito fiat cannot Valls r'afty is be seen In the planted repast Zone 24 volall.,n eudt that mosquito Salt area. vagatairon Annually. or ate special teenage and density to toatein caiwdi sdm freely In the density approidmately request of the local ver a etament efficacy planted area. 8010 100 parcelS Quarterly vedrr corbel agency - 0 - 0 --------0 I 1 0 0 Have, abalcglat SUM" ma Vft Basin to detemrine if any bIrds we nedng or other sensitive animals are preset If birds are nesting, with advice from the bIologist. proceed atth the 84 701 560 sedan i 21.281 21.28 581.28 Loser and mairdein I the water level to arose , the area to be melrtalned. do, net . completely drain basIn 41 4&63 174.52 one-ton hick 1 i 2t84t 26.84 _____ 20138 14 15 of 18 .P23P2003 -- -- - APPENDIX H Estimated 0 & M Costs for BMP Project Eathnatid stoves dsdved from Calvana Pd02 WAP Stodf. This spivadaheetwdl — Labor Equipment Matorfat, Totel Comment, change es additional date beccnwSevadode. perpir. Rate Coat Type D48 rate Cost Item Coat Cost 3.— removaCutTyphasp. (cebeil).Sdrpuaap. i (bultush) to produce vegetation rift ctusters (5 pt,) with clusters; hd took. at appm;drnalsly 0.5m2am0noan2ar4. bags,safety : tomaint,lnaiadoof I STyph.of21. : If the vegetation is cLrL I out the vegeodon to belowatepennanwa post water atg 56 43.631 2443.26 01e40n 31 213,84i 80.52 1 100 2623.8 Dlapoae of the vevetation maturtel Inc I hand toot,. IwatMorcow I . . Be" disposal arelk. 24: 0 padier 1 3, 5&44:16032 50 1192 Mother vegetation I density quarterly to . grow bade I raes. None 4 43.631 174.52 Cite.tflfl II 26.84 28.84 j _138 MaintaIn V.gelatad Access Road to reduce fir, hesard from osntactwte vuidde oatac converters. 0 I 0 0 0 0 ____ • 0 ________ ______ ______ ______ ______ ______ Moped W sediment More than 2 Inthes In Sediment depth accumtjatjon In tomboy and the tomboy and 4 Inches exceeds muter on ataivgeg..olffe main pond In the rholn Pond, or cyd. Measure inlorabayby — depth using I romp. In main pond Remove and propedy . by measuring down dispose, ofeedlmant. By from water quality Wian pond is drained November. mdees . I affimandcarriparing forZone 1 vegetation se5mlalion toth.plan to es.oanatiudad reinovel, or avery 3 shown on the as.bullt , I gmds, yeas. drawtnge. La Costa cite only - 10 0 ______________ 0 go cycie o _.L 0 j_ 0 i...___0 . 0 0 o I 0 TOTAL WET BAN g271.62 : 840•16 I 300 10412.38 -- inch-- . A target stcssn avant Is a Item greater than 0.7525 Inches of raInfall For drain Inlet Inserts, a beget storm event Is a stotin ettat a prediction of wMar than 0.25 *iejiX.pp).(pqMm fternont-5). and western sycernompMotasaresemoaa). Nate. bis aftetonk,ppcetit,foate wet buii ________ Zone 1. open water we. of the basin, overage depth I, about 3 fact Zone 2. ehaflow water bendt depth of water 0-12 IndteL Zones. pedodic Imeidatlon Is the tonporary astir storage volume knpountt.d between the permanent pod and the overflow wcir. I.e. the water quality Zone A Is the remaining upland elope betw.en Zone 3and the m..Ii1ane road. .- - ,l. tIa. I..44..&,,. fl,. k h... .4.,w4 .k.. I-S- _fr- . ,.4 •_. _._.4_II_ - Sa' .------ —4 - -. - .. — - '" - 1 _.* I...,h,,4 .,,a.4 •,_ I____, — ,_ 15 18 of 16 APPENDIX H Estimated 0 & M Costs for BMP vtaues deilved from CtfrI P6ot BMP Sbidy. This spadshoetwlll Fs8sr. some dew rrmftenance.em maidaft We based or the m*amIIIis of ipedftc pisnt spades used In lids Pilot Program. Theiew.u.mWatior provided In this dOa.gnart must be reassessed with lespsotto spades arid plarli the midanor condsnsd hereIn I. to be used far a sepret. praect In soother arts. 16 (k Aciie Hed;cncL C) — - 2'30" ' vv. I rtvv. I San Diego County Soils Interpretation Study HYDRO OGIC 801 GROUPS - Runoff Pa enlial