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CATEGORY 2 - ROOFS <br /> Roofs <br /> ■ BMP T5.30: Full Dispersion <br /> ■ BMP T5.10A: Downspout Full Infiltration <br /> ■ BMP T5.14: Rain Gardens <br /> ■ BMP T5.1013: Downspout Dispersion Systems <br /> ■ BMP T5.10C: Perforated Stub-out Connections <br /> BMP T5.30: Full Dispersion <br /> Full dispersion shall be designed in accordance with the SWMMWW. <br /> ■ Residential(impervious surfaces) <br /> Total Impervious (ft )*100%_ % (must be less than 10%to use BMP) <br /> Total Area (ft') <br /> ■ Required Dispersion Area (ft') =Total Impervious Area (ft')* 6.5 <br /> Required Dispersion Area(ft'): <br /> ■ Dispersion area provided (ft'): <br /> (Note:Dispersion area must be preserved as forest or native vegetation.) <br /> BMP T5.10A: Downspout Full Infiltration <br /> Downspout full infiltration systems include trenches or dry wells designed to infiltrate runoff from roof <br /> downspout drains and shall be designed in accordance with the SWMMWW. <br /> Infiltration Trench <br /> The minimum trench length depends on soil type.The soils report will provide the USDA Soil <br /> Type.The following table provides the minimum trench length per 1,000 ft'of roof area. <br /> oil .. <br /> "Coarse sand" <br /> (more than 50%of sand fraction remains on#4 sieve) 20 <br /> "Medium sand" <br /> (more than 50%of sand fraction remains on#40 sieve) 30 <br /> Loamy sand 75 <br /> Sandy loam 125 <br /> Loam 190 <br /> Silt loam 275 <br /> Fill (only per SWMMWW requirements) 60 <br /> City of Everett Public Works <br /> Small Project Stormwater Site Plan/Report—Sept.2023 Page 33 of 40 <br />