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

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Treatment Control MeasuresConsider the short and long-term maintenance needs of the treatment controlmeasures (as described on the fact sheets at the end of this chapter) and whetheror not the property owner can agree to those requirements. The permittingagencies in the Sacramento and South Placer Regions require that the propertyowner sign a maintenance agreement or obtain a permit to ensure long-termmaintenance. Such maintenance agreements require reconstruction orreplacement of the feature when it fails to function properly. For informationalpurposes, projected lifespan information is provided for the various controlmeasures in Appendix B.Designing Treatment Control MeasuresThe treatment control measures presented in this manual are sized and configuredusing either a volume-based or flow-based design approach, as explained in moredetail in Appendix E:Volume-Based Design (WQV)Treatment control measures that depend on storage and gravitational settling forpollutant removal (e.g., detention basins, vaults) are designed for the waterquality volume. Volume-based design criteria call for the capture and infiltrationor treatment of a certain percentage of the runoff from the project site, usually inthe range of the 75th to 85th percentile average annual runoff volume.Flow-Based Design (WQF)Flow-through treatment control measures that do not require long detentiontimes for pollutant removal (e.g., vegetated swales) are designed for the waterquality flow. Flow-based design criteria call for the capture and treatment of theflow produced by rain events of a specified magnitude, usually the 85 th percentilehourly rainfall intensity multiplied by a factor of 2.Appendix E includes instructions for calculating the expected water qualityvolume (WQV) or water quality flow (WQF) for your project. The procedurerequires you to determine the amount of impervious surfaces that will contributerunoff to the treatment control measures. In addition, site run-on that is notdiverted around the site and combines with other runoff may need to be treated,depending on the local agency requirements. Each situation will be handled on acase-by-case basis.Operation and MaintenanceThe property owner is ultimately responsible for the operation and maintenance andlong-term continued performance of the treatment control measure(s). Failure toproperly operate and maintain the measures could result in no treatment of siterunoff, or a slug loading of pollutants to the storm drain system. Both consequenceswill result in violation of the local permitting agencies' municipal codes, as well asstate and federal water quality regulations.Stormwater Quality Design Manual for the Sacramento and South Placer RegionsMay 2007 6-3
Chapter 6For projects using any of the treatment control measures in this chapter, verificationof long-term maintenance provisions is required. This is mandated by the agencies’State-issued stormwater permits. The local permitting agencies in the Sacramentoand South Placer areas require execution of a maintenance agreement, covenant orpermit with the property owner. Typically maintenance agreements and covenantsare recorded with the deed for the property and follow property ownership. Suchmaintenance agreements require reconstruction or replacement of the feature whenit fails to function properly. For informational purposes, Appendix B presentsprojected lifespan information for the various control measures.Check with the local permitting agency about the maintenance submittalrequirements and timing for execution of the agreement. See Appendix B foradditional information and a sample maintenance agreement .Treatment Control Measure Fact SheetsThe remainder of this chapter includes fact sheets for various treatment controlmeasures. Each fact sheets describe siting, design, construction considerations, andmaintenance requirements to ensure optimal performance of the measures.Proprietary Treatment Control MeasuresProprietary stormwater quality treatment measures are manufactured devicesintended to capture and treat post-construction site runoff to remove pollutants. Thepermitting agencies in Sacramento County and the City of Roseville allow certainproprietary devices for treatment of runoff, under certain conditions, as describedbelow.Agencies in Sacramento. Since the late 1990's, the Sacramento StormwaterQuality Partnership has been conducting a study to investigate and verify the fieldperformance of proprietary stormwater quality devices. In November 1999, thePartnership published a report that describes the protocol that must be followed inorder for a particular device to be accepted for use in the Sacramento area. Theprotocol is based on a comparison of the performance of the proprietary device tothat of widely- accepted public domain measures, such as vegetated swales.Manufacturers are invited to submit data that can be reviewed for conformance withthe protocol. In addition to devices accepted using the Sacramento area protocol, thePartnership will consider technologies with the Washington State Department ofEcology's General Use Level Designation for Basic (TSS) Treatment on a case by casebasis.For an updated list of accepted devices and more details on the Sacramentoproprietary study, see www.sacramentostormwater.org (new development). Inselect cases, the local permitting agency may allow the use of other proprietarytreatment measures as a "pilot study." In such cases, the property owner and/ormanufacturer will be required to fund and complete a monitoring study to verify thedevice's performance. Since approval is not guaranteed, site designers proposing touse an alternative technique should coordinate with the permitting agency early inthe site design process.Stormwater Quality Design Manual for the Sacramento and South Placer Regions6-4 May 2007
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Stormwater Quality Design Manualfor
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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 SheetOu
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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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Technical RequirementsSand FilterTa
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Technical RequirementsSand FilterLo
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Runoff Treatment Control Measure Fa
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Technical RequirementsVegetated Swa
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Glossaryexposure of construction ma
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GlossaryLow Impact Development (LID
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GlossaryRegional Stormwater Quality
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Appendix ASubmittal RequirementsThe
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Sacramento County Supplemental Appl
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Example Post Construction Stormwate
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Typically maintenance agreements an
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Example Maintenance Covenant(Sacram
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Device in accordance with the maint
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[attach]DECLARANT’S ACKNOWLEGEMEN
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Recorded at the request of:CITY OF
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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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