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<br />l, I, <br /> <br />Sediment..CtQntrol <br />-Sill t'ences <br /> <br />..-....:..... <br />.. <br /> <br /> <br />Description <br /> <br />A silt fence is a temporary barrier designed to retain sediment on tbe <br />construction site. It consists of a geotextile attached to supporting <br />posts tbat are trenched into tbe ground. The fence retains sediment <br />primarily by retarding flow and promoting deposition on the uphill side <br />of tbe fence. Runoff is also filtered as it passes through tbe <br />geotextile. <br /> <br />Silt fences are intended to intercept and detain sman amounts of <br />sediment from disturbed areas. They can also prevent sheet erosion <br />by decreasing the velocity of runoff In some instances, straw or hay <br />bales could be used, however their failure rate is high. <br /> <br />The use of silt fences as a sediment barrier is not recommended in <br />areas of concentrated flow, such as ditches. In those cases, soil <br />berms, silt dikes, straw wattles and excelsior logs, or rock check <br />dams should be used. <br /> <br />Advantages <br />Easy installation <br />Cost-effective <br />. Materials readily available <br />Widely accepted practice <br />Effectiveness is superior to straw bales <br /> <br />Limitations <br /> <br />Not effective for concentrated flows less tban 1.0 cfs <br /> <br />Proper instanation is critical for effective performance <br />. Frequent inspection and maintenance required <br /> <br />Metropolitan Council I Barr Engineering Co. <br /> <br />Purpose <br /> <br />Water Quantity <br />Flow attenuation 0 <br />Runoffvolume reduction 0 <br />Water Quality <br /> <br />Pollution prevention <br />Soil erosion . <br />Sediment control . <br />Nutrient loading IJ <br />Ponution removal <br />Total suspended sediment (TSS) 0 <br />Total phosphorus (P) 0 <br />Nitrogen (N) 0 <br />Heavy metals 0 <br />Floatables 0 <br />Oil aod grease 0 <br />Other <br />Fecal coliform 0 <br />Biochemical oxygen demaod 0 <br />(BOD) <br /> <br />II Primary design benefit <br /> <br /> <br />IJ Secondary design benefit <br /> <br /> <br />o Little or no design benefit <br /> <br />3-105 <br />