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0 AE CONSTRUCTION SFR <br />BMP T5.1 OB Downspout Dispersion Systems has been selected for proposed roof areas <br />and will consist of one 50'x2' dispersion trench for SFR addition roof areas, and 3 <br />dispersion splash pads for concentrated runoff from driveway areas per BMP T5.11. See <br />below for sizing: <br />Driveway Splash Pad Sizing <br />Proposed Driveway Area = 1,600 SF <br />1 Splash Block Required Per 700 SF Roof Area <br />Required Splash Pads = 1,600 SF / 700 SF = 2.3 <br />Designed Splash Pads = 3 <br />Proposed SFR Trench Sizing <br />Proposed Roof Area = 3,345 SF <br />2 x 10 LF of Trench Required Per 700 SF Roof Area <br />Total Required Trench Length = (3,345 SF / 700 SF) * 10 LF = 47.8 LF <br />Designed Trench Lengths = 50 LF <br />For driveway areas, the use of a berm and driveway grading will divide driveway runoff <br />into three areas. The berm will direct western driveway runoff to a splash pad. The two <br />remaining driveway areas will slope toward two catch basins on the northwest and <br />southeast corners of the driveway pad. These catch basins will collect runoff and convey it <br />via drainage lines to two separate splash pads located north and south of the proposed <br />residence. The site contains adequate area for the 50-foot vegetated flow path required for <br />the concentrated driveway runoff. These flow path areas will be graded to ensure that the <br />runoff flow paths remain on -site for at least 50 feet and do not cross other dispersion flow <br />paths. Refer to the drainage plan for flow path placement. <br />Minimum Requirement # 6: Runoff Treatment <br />Due to less than 5,000 sf of pollution generating hard surfaces and less than 3/ of an Acre <br />of pollution -generating pervious surfaces, runoff treatment is not required. <br />WESTERN ENGINEERS, INC. 17 PROJECT: 19-1821-A <br />