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� I <br />Figure II-4.2.8 Block and Gravel Filter <br />A <br />Drain grate <br />mac:. <br />Concrete block <br />I <br />C <br />III <br />Plan View <br />Gravel backfill <br />Concrete block <br />/� Wire screen or <br />/ filter fabric <br />Gravel backfill Overflow <br />- water Ponding height <br />re - <br />�' `o T <br />rop inlet <br />Section A -A <br />Notes: <br />1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less <br />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 the ground elevation <br />downslope to prevent runoff from bypassing the inlet. A temporary dike may be <br />necessary on the downslope side of the structure. <br />�r <br />DEPARTMENT OF <br />ECOLOGY <br />State of Washington <br />Figure II-4.2.8 <br />Block and Gravel Filter <br />NOT TO SCALE <br />Revised August 2015 <br />Please see http://www.ecy.wa.gov/copyright.html for copyright notice including permissions, <br />limitation of liability, and disclaimer. <br />2014 Stormwater Management Manual for Westem Washington <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />1 <br />F <br />1 <br />1 <br />1 <br />1 <br />1 <br />Volume 11 - Chapter 4 - Page 360 <br />1 <br />