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~•`yr-- e~~Jcr~ <br />1'~"F.TE~Sf~EC+ <br />f,,~--° ~F rTrt~r-,s may 2016 <br />4. Additional criteria for extended detention facilities: <br />a. The outlet shall be designed to not release more than the first half of the water <br />quality volume in less than 1/3rd of the drain time. The outlet shall be designed to <br />minimize clogging, vandalism, maintenance, and promote the capture of floatable <br />pollutants. <br />b. The basin design shall incorporate the following features to maximize multiple <br />uses, aesthetics, safety, and maintainability: <br />(1) Basin side slopes above the permanent pool shall have a run to rise ratio <br />of 4:1 or flatter. <br />(2) The perimeter of all permanent pool areas deeper than 4 feet shall be <br />surrounded by an aquatic bench that extends at least 8 feet and no more <br />than 15 feet outward from the normal water edge. The 8 feet wide <br />portion of the aquatic bench closest to the shoreline shall have an average <br />depth of 6 inches below the permanent pool to promote the growth of <br />aquatic vegetation. The remainder of the aquatic bench shall be no more <br />than 15 inches below the permanent pool to minimize drowning risk to <br />individuals who accidentally or intentionally enter the basin, and to limit <br />growth of dense vegetation in a manner that allows waves and mosquito <br />predators to pass through the vegetation. The maximum slope of the <br />aquatic bench shall be 10 (H) to 1 (V). The aquatic bench shall be <br />planted with native plant species comparable to wetland vegetation that <br />are able to withstand prolonged inundation. The use of invasive plant <br />species is prohibited. <br />(3) A forebay designed to allow larger sediment particles to settle shall be <br />placed at basin inlets. The forebay and micropool volume shall be equal <br />to at least 10% of the water quality volume (WQv). <br />(4) Detention basins shall be provided with an emergency drain, where <br />practicable, so that the basin maybe emptied if the primary outlet <br />becomes clogged and/or to drain the permanent pool to facilitate <br />maintenance. The emergency drain should be designed to drain by <br />gravity where possible. <br />Criteria for the Acceptance of Alternative post-construction SCMs: The applicant may <br />request approval from the Village Engineer for the use of alternative structural post- <br />construction SCMs if the applicant shows to the satisfaction of the Village Engineer that <br />these SCMs are equivalent in pollutant removal and runoff flow/volume reduction <br />effectiveness to those listed in Table 2. If the site is greater than five (5) acres, or less <br />than five (5) acres but part of a larger common plan of development or sale which will <br />disturb five (5) or more acres, prior approval from the Ohio EPA is necessary. To <br />demonstrate the equivalency, the applicant must show: <br />a. The alternative SCM has a minimum total suspended solid (TSS) removal <br />efficiency of 80 percent, using the Level II Technology Acceptance Reciprocity <br />23 <br />