Stormwater Quality Design Manual (May 2007) - City of Sacramento ...

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Technical RequirementsSand FilterStep 4 – Design Filter BedThe sand filter bed may be either of the two configurations given below. Sand bed depths are final,consolidated depths, so consolidation effects must be taken into account.a. Sand Bed with Gravel Underdrain (Figure SF-3)The sand layer shall be a minimum depth of 18 inches and shall consist of 0.02 to 0.04-inchdiameter sand. Below the sand is a layer of 0.5 to 2-inch diameter gravel that provides aminimum of two (2) inches of cover over the top of the underdrain lateral pipes. No gravel isrequired under the lateral pipes. A layer of geotextile fabric meeting the specifications in TableSF-2 must separate the sand and gravel and must be wrapped around the lateral pipes.Drainage matting meeting the specifications in Table SF-2 should be placed under the laterals toprovide for adequate vertical and horizontal hydraulic conductivity to the laterals.In areas with expected high sediment loads (total suspended solids concentration ≥ 200 mg/L),the two-inch layer of gravel on top of the sand filter should be underlain with Enkadrain 9120filter fabric or equivalent meeting the specifications in Table SF-2.b. Sand Bed with Trench Underdrain (Figure SF-4)The top layer shall be 12-18 inches of 0.02 to 0.04-inch diameter sand. Laterals shall be placed intrenches with a covering of 0.5 to 2-inch gravel and geotextile fabric (see Table SF-2). Thelaterals shall be underlain by a layer of drainage matting (see Table SF-2).In areas with expected high sediment loads, see the note above about use of Enkadrain filterfabric or equivalent.Step 5 – Design Underdrain PipingThe underdrain piping consists of the main collector pipe(s) and perforated lateral branch pipes (see planview in Figure SF-1). The piping should be reinforced to withstand the weight of the overburden. Internaldiameters of lateral branch pipes should be six inches or greater and perforations should be 3/8 inch. Eachrow of perforations should contain at least six holes and the maximum spacing between rows ofperforations should not exceed six inches. All piping is to be Schedule 40 polyvinyl chloride (PVC) orgreater strength. The minimum slope of piping shall be 1/8 inch per foot (one (1) percent; slopes down toone-half (0.5) percent may be acceptable to the permitting agency). Access for cleaning all underdrainpiping is needed.Note: Unlike the sedimentation basin, the filtration basin does not require a drawdown time for release.Thus, it is not necessary to have a specifically-designed orifice for the filtration basin outlet structure.Step 6 – Design Filtration Basin LinerIf the filtration basin is an earthen structure and an impermeable liner is required to protect groundwaterquality, the liner shall provide a maximum permeability of 1x10 -6 cm/sec (ASTM Method D-2434). If animpermeable liner is not required, then install a geotextile fabric liner that meets the specifications listedin Table SF-3 unless the basin has been excavated to bedrock.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsSF-8 May 2007
Technical RequirementsSand FilterTable SF-2. Geotextile Fabric and Drainage Matting Specifications for Sand FiltersProperty Test Method SpecificationsGeotextile FabricMaterialNon-woven geotextile fabricUnit Weight8 oz./yd (minimum)Filtration Rate0.08 in./sec (minimum)Puncture Strength ASTM D-751 (Modified) 125 lbs (minimum)Mullen Burst Strength ASTM D-751 400 psi (minimum)Tensile Strength ASTM-D-1682 300 lbs (minimum)Equivalent Opening Size US Standard Sieve No. 80 (minimum)Drainage MattingMaterialNon-woven geotextile fabricUnit Weight20 oz./yd (minimum)Flow Rate (fabric)180 gpm/ft 2 (minimum)Permeability ASTM D-2434 12.4 x 10 -2 cm/secGrab Strength ASTM D-1682 Dry: Lg 90/Wd 70; Wet: Lg 95/Wd 70Puncture Strength COE CW-02215 42 lbs (minimum)Mullen Burst Strength ASTM-D-1117 400 psi (minimum)Equivalent Opening Size ASTM-D-1682 No. 100 (70-120)Flow Rate (Drainage Core) Drexel University 14 gpm/ft widthFilter FabricMaterialNon-woven geotextile fabricUnit Weight4.3 oz./yd (minimum)Filtration Rate120 gpm/ft 2 (minimum)Puncture Strength ASTM D-751 (Modified) 60 lbs (minimum)Thickness0.8 in. (minimum)Construction Considerations• Divert flow around the sand filter to protect it from sediment loads during construction. Ifsediment does enter the facility during construction, the contractor will be required to remove soilfrom the unit after the entire site has been stabilized, to the satisfaction of the permitting agencyinspector.• Where underdrains are used, ensure that the minimum slope of the pipe is 0.5 (1/2) percent.Where only gravel filtered water conveyance is provided, slope the filter floor towards theweepholes at a minimum of 0.5 (1/2) percent.• Ensure that the inverts of the notches, multiple orifices, or weirs dividing the sedimentationchamber from the filtration basin are completely level. Otherwise, water will not arrive at thefiltration basin as sheet flow, and only the downgradient end of the filtration basin will function.• Inflow grates or slotted curbs may conform to the grade of the completed pavement as long as thefilters, notches, multiple orifices, and weirs connecting the sedimentation and filter chambers arecompletely level.• Level the top of the sand filter bed in the filtration basin; no slope is allowed.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007SF-9
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Stormwater Quality Design Manualfor
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Stormwater Quality Design Manual wa
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Table of contentsOutdoor Work Areas
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Table of contentsSF-1.SF-2.SF-3.SF-
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Other Development Community Reviewe
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1 IntroductionPurposeThis Stormwate
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IntroductionIn July 2003, the permi
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IntroductionFor redevelopment proje
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Introduction• The Appendices prov
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2 An Integrated Approach toEffectiv
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Integrated ApproachIt is also helpf
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Integrated ApproachPut landscaping
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Integrated Approachfactors will be
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Chapter 3Figure 3-1. Process for Ad
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Chapter 3runoff reduction first (ev
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Chapter 3As the name implies (and a
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Chapter 3Step 9: Establish Long Ter
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Chapter 4Source Control Fact Sheets
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Source Control Measure Fact SheetSt
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Source Control Measure Fact SheetFu
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Source Control Measure Fact SheetLo
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Source Control Measure Fact SheetOu
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Source Control Measure Fact SheetOu
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Source Control Measure Fact SheetWa
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Source Control Measure Fact SheetWa
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5 Runoff Reduction Control Measures
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Runoff Reduction Control MeasuresDe
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Runoff Reduction Control Measures
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Runoff Reduction Control Measure Fa
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Runoff Reduction Fact SheetDisconne
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Chapter 6• What are pollutants of
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Chapter 6For projects using any of
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Runoff Treatment Control Measure Fa
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Page 119 and 120: Design Data Summary SheetConstructe
Page 141 and 142: Technical RequirementsInfiltration
Page 157 and 158: Technical RequirementsSand FilterSa
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Page 177 and 178: Technical RequirementsVegetated Swa
Page 191 and 192: Glossaryexposure of construction ma
Page 193 and 194: GlossaryLow Impact Development (LID
Page 195 and 196: GlossaryRegional Stormwater Quality
Page 197 and 198: Appendix ASubmittal RequirementsThe
Page 199 and 200: Sacramento County Supplemental Appl
Page 201: Example Post Construction Stormwate
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Page 206 and 207: Example Maintenance Covenant(Sacram
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Page 210 and 211: [attach]DECLARANT’S ACKNOWLEGEMEN
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9. The obligations herein undertake
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EXHIBIT B[Map/Illustration]
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City of FolsomThe City of Folsom ow
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Appendix D-1: Residential Sites: Ru
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Form D-1d: Alternative Driveway Des
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Form D-2a: Disconnected Pavement Wo
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Appendix D-3Runoff Reduction Credit
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These tables refer to runoff reduct
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Mature TreeShape Canopy (dia.) Heig
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Appendix D4LID Credits Background R
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unoff from the driveway by 60% whil
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The designer must determine how man
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Or the ASCE-WEF method (Sacramento)
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Table 3 - Multipliers Based on Rati
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Using the Effective Area Managed in
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SMRC, The Stormwater Manager’s Re
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Flow-based control measure design s
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4. Apply the Rational Formula to ca
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5. Enter the capture curve selected
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1.201.000.80STORAGE (in)0.600.4024-
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1.201.000.80STORAGE (in)0.600.4048
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Subject: VEGETATED SWALE EXAMPLEPLA
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PART II:Routing Excess Runoff throu
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4. Design the OutletThe outlet shou
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Exhibit 1Water Quality Orifice Outl
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3. Calculate Planter Surface Area A
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• Bottom slopes of 0.01 to 0.05%
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Appendix HDrainage Design and Storm
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