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r <br /> Chapter 4 - Best Management Practices for Erosion and Sediment Control <br /> 4.38 TEMPORARY CHECK DAMS <br /> Definition <br /> Small temporary dams constructed across a swale or stormwater conveyance channel . <br /> Purpose <br /> To reduce the velocity of concentrated stormwater flows , thereby reducing erosion of the <br /> swale or ditch . This practice also traps small amounts of sediment generated in the ditch <br /> itself. These sediments will require periodic removal . However, this is not a sediment <br /> trapping practice and should not be used as such . <br /> Conditions Where Practice Applies <br /> r This practice is limited to use in small open channels which drain 10 acres (4 ha) or less . It <br /> should not be used in a live stream . This practice is especially applicable to sloping sites <br /> where the gradient of waterways is close to the maximum for a grass lining . Some specific <br /> applications include: <br /> 1 . Temporary ditches or swales which , because of their short length of service , cannot <br /> r receive a non-erodible lining but still need some protection to reduce erosion . <br /> 2 . Permanent ditches or swales which for some reason cannot receive a permanent <br /> non-erodible lining for an extended period of time . <br /> 3 . Either temporary or permanent ditches or swales which need protection during the <br /> r establishment of grass linings. . <br />_ Planning Considerations <br /> Temporary check dams can be constructed of filter fence or straw bales for very short term <br /> applications ; or either stone or logs for longer or permanent applications . Filter fence and <br /> straw bale check dams are economical to purchase and simple to install . Log check dams <br /> are economical as for material costs, since logs can usually be salvaged from clearing <br /> operations . However, log check dams require more time and hand labor to install . Stone <br /> for check dams , on the other hand , must generally be purchased . However, this cost is <br /> offset somewhat by the ease of installation . <br /> Specifications <br /> No formal design is required for a check dam; however, the following criteria should be <br /> adhered to when specifying check dams . <br /> r <br /> s <br /> 4-105 <br />