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Treated 2"x10" may be abutted end to <br />Spreader must be level end for max. spreader length of 50' <br />6" min. 1" min. <br />__ - ....... _ _.._...__ _........ - _ ....... - .............. _ .__...... .....- - _ .._.. -. ...... _ <br />I1 I 6" min.1 <br />=�IIIIII� �III�E��IIEll II��1 1II=-++1=II�IIIIIIIIIIII II���IIIIII��� <br />18" min, rebar supports <br />8' max. spacing <br />Figure 4.2.6 - Detail of Level Spreader <br />BMP C207: Check Dams <br />Purpose Construction of small dams across a swale or ditch reduces the velocity of <br />concentrated flow and dissipates energy at the check dam. <br />Conditions of Use Where temporary channels or permanent channels are not yet vegetated, <br />channel lining is infeasible, and/or velocity checks are required. <br />• Check dams may not be placed in streams unless approved by the State <br />• Department of Fish and Wildlife. Check dams may not be placed in <br />wetlands without approval from a permitting agency. <br />• Do not place check dams below the expected backwater from any <br />salmonid bearing water between October 1 and May 31 to ensure that <br />there is no loss of high flow refuge habitat for overwintering juvenile <br />salmonids and emergent salmonid fry. <br />• <br />Construct rock check dams from appropriately sized rock. The rock <br />used must be large enough to stay in place given the expected design <br />flow through the channel. The rock must be placed by hand or by <br />mechanical means (no dumping of rock to form dam) to achieve <br />complete coverage of the ditch or swale and to ensure that the center <br />of the dam is lower than the edges. <br />Check dams may also be constructed of either rock or pea -gravel filled <br />bags. Numerous new products are also available for this purpose. They <br />tend to be re -usable, quick and easy to install, effective, and cost <br />efficient. <br />• Place check dams perpendicular to the flow of water. <br />• The dam should form a triangle when viewed from the side. This <br />prevents undercutting as water flows over the face of the dam rather <br />than falling directly onto the ditch bottom. <br />Volume 11- Construction Stormwater Pollution Prevention - August 2012 <br />4-73 <br />