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Notched Grade Board Trench <br />For roof areas larger than 700 ft2, dispersion trenches with notched grade boards may be used with <br />a total length not to exceed 50 ft. <br />Notched Grade Board Trench Length (ft) = (10 ft)* (Roof Area to Trench (ft')) <br />700 (ft2) <br />■ Notched grade board trench length required: <br />If greater than 50 feet needed more than one trench will be required <br />■ Number of notched grade board trenches required: <br />■ Length of each notched grade board trenches: — <br />❑ See attached sketch. <br />Splashblocks <br />Splashblocks shall be designed in accordance with the SWMMWW. A maximum of 700 ft2 of roof <br />area can drain to a single splashblock. <br />■ Roof area requiring mitigation: <br />■ Roof area discharging to splashblock: <br />❑ See attached sketch. <br />BMP T5.10C Perforated Stub -out Connections <br />Perforated stub -out connections shall be designed in accordance with the SWMMWW. <br />■ Roof area requiring mitigation (ft2): <br />■ Roof area discharging to perforated stub -out connection: <br />■ Perforated pipe length (ft): <br />Perforated Pipe Length (ft) = (10 ft)*(Roof Area to Facility_(ft2)) <br />5000 (ft2) <br />The minimum perforated pipe length shall be 10 ft. <br />City of Everett Public Works <br />Small Project Stormwater Site Plan Report -Dec 2019 40 <br />