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Florida Erosion and Sediment Control Inspector's Manual ■" <br /> 4 . 26 TEMPORARY SEDIMENT BASIN , <br /> ( ES BMP 1 . 26 ) <br /> Definition <br /> A temporary basin with a controlled stormwater release structure , formed by constructing an <br /> embankment of compacted soil across a drainageway. <br /> Purpose <br /> To detain sediment-laden runoff from disturbed areas long enough for most of the sediment <br /> to settle out . <br /> Conditions Where Practice Applies <br /> Below disturbed areas greater than 5 acres (2 ha) . There must be sufficient space and <br /> appropriate topography for the construction of a temporary impoundment. These structures <br /> are limited to a useful life of 18 months unless they are designed as permanent ponds by a <br /> .w <br /> qualified professional engineer. <br /> Planning Considerations <br /> .r <br /> Effectiveness <br /> Sediment basins are at best only 70-80% effective in trapping sediment which flows into them . <br /> Therefore , they should be used together with erosion control practices such as temporary <br /> seeding , mulching , diversion dikes , etc. to reduce the amount of sediment flowing into the <br /> basin . <br /> Location �. <br /> To improve the effectiveness of the basin , it should be located so as to intercept the largest <br /> possible amount of runoff from the disturbed area . The best locations are generally low areas ,. <br /> and natural drainageways below disturbed areas . Drainage into the basin can be improved <br /> by the use of diversion dikes and ditches . The basin must not be located in a live stream but <br /> should be located to trap sediment-laden runoff before it enters the stream . The basin should .� <br /> not be located where its failure would result in the loss of life , damage to adjacent properties , <br /> or interruption of the use of public utilities or roads . <br /> Multiple Use <br /> Sediment basins may be designed as permanent structures to remain in place after ■ <br /> construction is completed . The Stormwater Rule (Ch . 62-25 , F .A.C . ) makes the use of these <br /> structures desirable for stormwater detention purposes . Always leave the bottom of the <br /> sediment basin 6" - 12" higher than the eventual bottom of a retention basin . This will ensure ■ <br /> removal of accumulated fine sediments which could prematurely clog the retention basin . <br /> Wherever these structures are to become permanent , or if they exceed the size limitations of <br /> 4-80 <br />