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A. Concentrated storm water runoff. <br />B. Runoff from drainage areas that exceeds the design capacity of silt fence or <br />inlet protection. <br />C. 10-acres of disturbed land. <br />The sediment-settling pond shall provide both a sediment storage zone and a dewatering <br />zone. The volume of the dewatering zone shall be at least 67 cubic yards of storage per <br />acre of total contributing drainage area and have a minimum of 48-hour drain time for <br />sediment basins serving a drainage area over 5 acres. <br />When post-construction detention/water quality ponds are to be used as temporary sediment <br />trapping BMP, a skimmer discharge device consistent with the Ohio Rainwater Manual shall <br />be utilized during construction phase and until the site is deemed permanently stabilized by <br />the administrator. <br />The volume of the sediment storage zone shall be calculated by one of the following <br />methods: <br />A. The volume of the sediment storage zone shall be 1000ft3 per disturbed acre <br />within the watershed of the basin. <br />B. The volume of the sediment storage zone shall be the volume necessary to <br />store the sediment as calculated with a generally accepted erosion prediction <br />model. <br />When determining the total contributing drainage area, off-site areas and areas which <br />remain undisturbed by construction activity must be included unless runoff from these <br />areas is diverted away from the sediment settling pond and is not co-mingled with <br />sediment-laden runoff. The depth of the dewatering zone must be less than or equal to five <br />(5) feet. The configuration between the inlets and the outlet of the basin must provide at <br />least two units of length for each one unit of width (> 2:1 length:width ratio), however a <br />length to width ration of 4:1 is recommended. Sediment must be removed from the <br />sediment-settling pond when the design capacity has been reduced by 40 percent. This <br />limit is typically reached when sediment occupies one-half of the basin depth. When <br />designing sediment settling ponds, the applicant must consider public safety, especially as <br />it relates to children, as a design factor for the sediment basin and alternative sediment <br />controls must be used where site limitations would preclude a safe design. The use of a <br />combination of sediment and erosion control measures in order to achieve maximum <br />pollutant removal is encouraged. <br />3 <br />( <br />) <br />, ~ <br />.. o .. <br />., ., <br />n , <br />D <br />~ <br />b Y <br />11.l,.,.l;,,1l7 7T;71.,,.., R„~.;,,oar ~ <br />~~ <br />~ <br />'TI, ,1' + ~o++l: .,.1 X1,.,11 l,o oa +.. ,;.lo ~+ la e+ ~'7 ,. ,L,' ,..1~ .,F ~+„ <br />iv :j .~......~ ....,.,....".b.°. t.,°.. <br />e <br />