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sedimentation basin, the control structure for the permanent pond can <br />• be used to maintain predevelopment discharge limitations. The size of <br />the basin, the expected life of the construction project, the anticipated <br />downstream effects and the anticipated weather conditions during <br />construction, should be considered to determine the need of additional <br />discharge control. See Figure 4.2.21 for riser inflow curves. <br />• <br />Key divider into slope <br />to prevent flow <br />around sides <br />The pond length shall be 3 to 6 <br />times the maximum pond width Emergency overflow <br />spillway <br />_Pon length iserpip ---� <br />Inflow <br />Silt fence or fDischarge to stabilized <br />equivalent divider conveyance, outlet, or <br />level spreader <br />Note: Pond may be formed by berm or <br />by partial or complete excavation <br />Figure 4.2.18 — Sediment Pond Plan View <br />Riser pipe <br />(principal spillway) Crest of <br />open at top with emergenc spillway U min. Width <br />trash rack - <br />s MOH. Embankment compacted 95% <br />�.J( Dewatering device ervious materials such as <br />(see riser detail) m gravel or clean sand shall <br />a- ay not be used <br />Wire -backed silt fence A�14 Discharge to stabilized <br />Dewatering Concrete base conveyance outlet or <br />staked haybales wrapped orifice (see riser detail) level spreader <br />with filter fabric, or <br />equivalent divider <br />Figure 4.2.19 — Sediment Pond Cross Section <br />Volume Il — Construction Stormwater Pollution Prevention - August 2012 <br />4-106 <br />