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Plan View <br />Drain <br />G rate <br />� <br />�. <br />Concrete <br />BloCk <br />Gravel <br />Backfill <br />,SeCtl�n A, ' a Concrete Block—� Wire Screen or <br />Filter Fabric <br />Gravel Backfill — Overflow <br />\ � Water Ponding Height <br />0 <br />�o -- �- � ---� � -- <br />0 <br />_ v��n.�/°�on�° ��Water ; II! I �� i i� �! i°,��no���°, ����. <br />Drop Inlet <br />. . ,. 1 I /� _ _ I J,. .- ,. . <br />Notes: <br />1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%) <br />2. Excavate a basin of sufficient size adjacent to the drop inlet. <br />3. The top of the structure (ponding height) must be well below thc ground elevation downslope to prcvent <br />runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure. <br />Figure 4.14 — Block and Gravel Filter <br />Gravel and Wire Mesla Filtej• - A gravel barrier placed over the top of the <br />inlet. This structure does not provide an overflow. <br />• Hardware cloth or comparable wire mesh with '/2-inch openings. <br />• Coarse aggregate. <br />• Height 1-foot or more, 18 inches wider than inlet on all sides. <br />• Place wire mesh over the drop inlet so that the wire extends a <br />minimum of 1-foot beyond each side of the inlet structure. <br />• If more than one strip of inesh is necessary, overlap the strips. <br />• Place coarse aggregate over the wire mesh. <br />• The depth of the gravel should be at least l 2 inches over the entire <br />inlet opening and extend at least l8 inches on all sides. <br />4-84 Volume ll — Construction Stormwater Pollution Prevention February 2005 <br />