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Flow Chart to Determine Performance Requirements. Start Here . Is the project Exempt or does not discharge to MS4? . YES NO. Project is < 2,500 ft 2 of new and replaced impervious surface. YES NO. P roject is a detached single-family residence?.

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  1. Flow Chart to Determine Performance Requirements Start Here Is the project Exempt or does not discharge to MS4? YES NO Project is < 2,500 ft2of new and replaced impervious surface YES NO Project is a detached single-family residence? YES NO SFR > 2,500 ft2 See Figure A4 EXEMPT No Stormwater Requirements All Others See Figure A2 Figure A1. Initial Screening for All Development Projects

  2. Projects ≥ 2,500 ft2 Project is >5,000 ft2net impervious area but < 15,000 ft2of new and replaced impervious surface Project is > 2,500 ft2of new and replaced impervious surface but < 5,000 ft2 of net impervious area Project is >15,000 ft2of new and replaced impervious surface Performance Requirements #1 (Site Design) and #2 (WQ Treatment) Performance Requirement #1 (Site Design) See Figure A3 Figure A2. Requirements for Small to Moderate Development Projects

  3. Projects ≥ 15,000 ft2 New and Replaced Impervious Area See Special Circumstances (Performance Requirement #5) Does the project fall under the Special Circumstances designation? Yes No Determine WMZ and apply Performance Requirement #3 (Runoff Retention) Watershed Management Zone 1 2 3 4 5 6 7 8 9 10 Retain 95th Percentile event via infiltration Retain 95th Percentile event via storage, harvesting, infiltration, and/or evapotranspiration N/A Retain 95th Percentile event via infiltration where overlying groundwater basin Retain 85th Percentile event via infiltration Retain 85th Percentile event via storage, harvesting, infiltration, and/or evapotranspiration Retain 95th Percentile event via infiltration where overlying groundwater basin Retain 85th Percentile event via infiltration Retain 85th Percentile event via storage, harvesting, infiltration, and/or evapotranspiration Retain 95th Percentile event via infiltration where overlying groundwater basin No No additional Stormwater Requirements Project in WMZ 1, 2, 3, 6, or 9 Yes No Project creates > 22,500 ft2 of new and replaced impervious surface Yes • Apply Performance • Requirement #4 • (Peak Management) Figure A3. Requirements for Large Development Projects

  4. DetachedSingle-FamilyResidentialProjects Project is > 2,500 ft2new and replaced impervious surface, but < 15,000 ft2 net impervious area Project is > 15,000 ft2 net impervious area, but < 22,500 ft2 new and replaced impervious surface Project is > 22,500 ft2 new and replaced impervious surface Performance Requirement #s 1, 2, and 3 Performance Requirement #s 1, 2, 3, and 4 Performance Requirement #1 Figure A4. Requirements for Single-Family Residential Projects

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