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Chapter 4 - Best Management Practices for Erosion and Sediment Control <br /> 4.25 TEMPORARY SEDIMENT TRAP <br /> ( ES BMP 1 . 25 ) <br /> Definition <br />.. A small temporary ponding area formed by excavation and/or an embankment across a <br /> drainageway. <br /> Purpose <br /> To detain sediment-laden runoff from small disturbed areas long enough to allow most of <br />.. the sediment to settle out thereby protecting drainageways, properties , and rights-of-way <br /> from sedimentation . <br /> Conditions Where Practice Applies <br /> 1 . A sediment trap is usually installed in a drainageway, at a storm drain inlet or at <br /> other points of discharge from a disturbed area . <br /> 2 . Below drainage areas of 5 acres (2 ha) or less . <br /> 3 . Where the sediment trap will be used less than 18 months . <br /> 4. The sediment trap may be constructed either independently or in conjunction with <br /> a TEMPORARY DIVERSION DIKE - Section 4 . 15 (ES BMP 1 . 15) . <br /> M Planning Considerations <br /> The sediment trap should be located to obtain the maximum storage benefit from the <br /> terrain , for ease of clean out and disposal of the trapped sediment and to minimize <br /> interference with construction activities . <br /> Sediment traps should be used only for small drainage areas . If the contributing drainage <br /> area is greater than 5 acres (2 ha) , refer to SEDIMENT BASINS - Section 4 .26 ( ES BMP <br /> 1 . 26) . <br /> Sediment must be periodically removed from the trap. Plans should detail how this <br /> sediment is to be disposed of, such as by use in fill areas on site or removal to an <br /> approved off-site dump . <br /> i <br /> Sediment traps , along with other perimeter controls , shall be installed before any land <br /> disturbance takes place in the drainage area . <br /> 4-67 <br />