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Figure 11-4.2.8 Block and Gravel Filter <br />Drain grate <br />m`'hry C <br />0 <br />A <br />Plan View <br />crate block <br />Gravel backfill <br />Concrete block <br />Wire screen or <br />filter fabric <br />Gravel backfill Overflow — <br />o, water Ponding height <br />Drop 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 />NOT TO SCALE <br />Figure II-4.2.8 <br />Block and Gravel Filter <br />DEPARTMENT OF Revised August2015 <br />ECOLOGY Please see httpYAvww.ecy.wa.gov/copyright html for copyright notice including permissions, <br />State of Washington limitation of liability, and disclaimer. <br />2014 Stommwater Management Manual for Westem Washington <br />Volume 11 - Chapter 4 - Page 360 <br />