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W kfi-- <br /> Option 3. Detention Design Worksheet <br /> Table 3: Small Project Detention Sizing <br /> OS- d\U1 \IAV t w <br /> Total Contributing Area to <br /> Detention System, (sf) Riser Height,overflow Riser Detention Detention Pipe <br /> Sizing Acres Orifice Size elevation above invert Diameter Pipe Diameter Length Required <br /> Selected At least but less than* (max) (in) of outlet pipe,(ft) (in) (in) (ft) <br /> 200 400 0.0092 0.375 1.5 6 18 20 <br /> _ _ 400 600 0.0138 0.375 1.5 8 18 24 <br /> _ _ 600 800 0.0184 0.375 1.5 8 18 28 <br /> _ 800 1000 0.0230 0.5 1.5 8 18 33 <br /> _ _ 1000 1200 0.0275 0.5 1.5 8 18 40 <br /> — 1200 1400 0.0321 0.5 1.5 8 18 55 <br /> 1400 1600 0.0367 0.5 1.5 8 18 70 <br /> 1600 1800 0.0413 0.5 2.0 8 24 60 <br /> 1800 2000 0.0459 0.5 2.0 8 24 65 <br /> *For projects directing more than this total area draining to the detention facility, size using a continuous runoff model(WWHM, <br /> MGS Flood etc.). Do not use this table to size facility. <br /> Outlet pipe shall be set 3" above bottom of detention pipe to allow for sediment storage. <br /> • Net new impervious area requiring mitigation (ft2): <br /> • Contributing impervious area to BMP: <br /> • Total contributing area including landscaped area (ft2): <br /> All underground stormwater facilities shall be setback from any structure or property line a distance equal to the depth of the <br /> ground disturbed in setting the structure. <br /> Applicable access requirements of DCSS 4-4.2 (3) have been met. <br />