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22 <br />Slightly susceptible wetland types include: floodplain forests and fresh wet <br />meadows or shallow marshes dominated by cattail giant reed, reed canary grass or <br />purple loosestrife. <br />Least susceptible wetland includes severely degraded wetlands. Examples of <br />this condition include cultivated hydric soils, dredge/fill disposal sites and some gravel <br />pits. <br />Exceptions. Rate control criteria of division (5) may be waived if the site <br />discharges directly to a water body with large storage capacity (such as a public water) <br />that has a time-to-peak elevation greater than that for an on-site pond and the volume <br />discharged from the on-site pond is negligible, relative to the volume of runoff entering <br />the water body. <br />(6)(7) Design criteria. Best Management Practices shall be designed in accordance <br />with the following standards: <br />(a) Infiltration BMPs. Infiltration BMPs must be designed to provide:The City <br />adopts by reference RCWD Rules C.9.(a) as amended. <br />1. Adequate pretreatment measures to remove sediment before runoff enters <br />the primary infiltration area; <br />2. Drawdown within 48-hours or 72-hours from the end of a storm event, for <br />surface or sub-surface features, respectively. Soil infiltration rates shall be based on the <br />appropriate HSG classification and associated infiltration rates (Table 5). Infiltration area <br />will be limited to the horizontal areas subject to prolonged wetting; <br />Table 5. Soil Infiltration Rates. <br />HSG Soil <br />Tecture* <br />Corresponding Unified <br />Soil Classification** <br />Infiltration <br />Rate <br />[in/hr] <br />A Gravel <br />Sandy <br />Gravel <br />Silty <br />Gravel <br />GW Well-graded <br />gravels, sandy <br />gravels <br />1.63 <br />GP Gap-graded or <br />uniform <br />gravels, sandy <br />gravels <br />GM Silty Gravels, <br />silty sandy <br />gravels <br />SW Well-graded or <br />uniform sands, <br />gravelly sands