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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br />2 <br />3 <br />c. Minimum volume of excavation 3.5 cubic yards <br />d. Shape basin to fit site with longest dimension oriented toward the longest inflow area <br />e. Install provisions for draining to prevent standing water problems <br />f. Clear the area of all debris <br />g. Grade the approach to the inlet uniformly <br />h. Drill weep holes into the side of the inlet <br />i. Protect weep holes with screen wire and washed aggregate <br />j. Seal weep holes when removing structure and stabilizing area <br />k. It may be necessary to build a temporary dike to the down slope side of the structure to <br />prevent bypass flow. <br />Block and Gravel Filter — A barrier formed around the storm drain inlet with standard concrete <br />blocks and gravel. See also DCSS Drawing # 209. <br />a. Height 1 to 2 feet above inlet <br />b. Recess the first row 2 inches into the ground for stability <br />c. Support subsequent courses by placing a 2 x 4 through the block opening <br />d. Do not use mortar <br />e. Lay some blocks in the bottom row on their side for dewatering the pool <br />f. Place hardware cloth or comparable wire mesh with one -half -inch openings over all <br />block openings <br />g. Place gravel just below the top of blocks on slopes of 2:1 or flatter <br />h. An alternative design is a gravel donut <br />i. Inlet slope of 3:1 <br />j. Outlet slope of 2:1 <br />k. 1-foot wide level stone area between the structure and the inlet <br />1. Inlet slope stones 3 inches in diameter or larger <br />m. Outlet slope use gravel one-half to three -fourths inches at a minimum thickness of <br />1 foot. <br />Gravel and Wire Mesh Filter — A gravel barrier placed over the top of the inlet. This structure <br />does not provide an overflow. See DCSS Drawing # 210. <br />a. Hardware cloth or comparable wire mesh with one -half -inch openings <br />b. Coarse aggregate <br />c. Height 1 foot or more, 18 inches wider than inlet on all sides <br />d. Place wire mesh over the drop inlet so that the wire extends a minimum of 1 foot beyond <br />each side of the inlet structure <br />e. If more than one strip of mesh is necessary, overlap the strips <br />f. Place coarse aggregate over the wire mesh <br />Volume 11 — Construction Stormwater Pollution Prevention <br />3-50 <br />