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. Grade the approach to the inlet uniformly. <br /> . Drill weep holes into the side of the inlet. <br /> . Protect weep holes with screen wire and washed aggregate. <br /> . Seal weep holes when removing structure and stabilizing area. <br /> . Build a temporary dike, if necessary,to the down slope side of the structure to prevent bypass <br /> flow. <br /> Block and Gravel Filter <br /> A block and gravel filter is a barrier formed around the inlet with standard concrete blocks and gravel. <br /> See Figure 11-3.17: Block and Gravel Filter. Design and installation specifications for block gravel fil- <br /> ters include: <br /> . Provide a height of 1 to 2 feet above the inlet. <br /> . Recess the first row of blocks 2-inches into the ground for stability. <br /> . Support subsequent courses by placing a pressure treated wood 2x4 through the block open- <br /> ing. <br /> . Do not use mortar. <br /> . Lay some blocks in the bottom row on their side to allow for dewatering the pool. <br /> . Place hardware cloth or comparable wire mesh with 1/2-inch openings over all block openings. <br /> . Place gravel to just below the top of blocks on slopes of 2H:1V or flatter. <br /> . An alternative design is a gravel berm surrounding the inlet, as follows: <br /> O Provide a slope of 3H:1 V on the upstream side of the berm. <br /> • Provide a slope of 2H:1 V on the downstream side of the berm. <br /> Provide a 1-foot wide level stone area between the gravel berm and the inlet. <br /> Use stones 3 inches in diameter or larger on the upstream slope of the berm. <br /> Use gravel'/2-to'/-inch at a minimum thickness of 1-foot on the downstream slope of <br /> the berm. <br /> 2019 Stormwater Management Manual for Western Washington <br /> Volume ll- Chapter 3-Page 358 <br />