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1 1 1 1 1 rl" 1 1 F_� 1 1 J 1 1 1 1 1 1 . The material used dictates the effectiveness period of the wattle. Generally, Wattles are typically effective for one to two seasons. . Prevent Tilling beneath wattles by properly entrenching and abutting wattles together to prevent water from passing between them. Design Criteria • Install wattles perpendicular to the flow direction and parallel to the slope contour. . Narrow trenches should be dug across the slope on contour to a depth of 3- to 5- inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5- to 7- inches, or 1/2 to 2/3 of the thickness of the wattle. • Start building trenches and installing wattles from the base of the slope and work up. Spread excavated material evenly along the uphill slope and compacted using hand tamping or other methods. • Construct trenches at intervals of 10- to 25-feet depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. . Install the wattles snugly into the trenches and abut tightly end to end. Do not over- lap the ends. . Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. . If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • Wooden stakes should be approximately 3/4 x 3/4 x 24 inches min. Willow cuttings or 3/8-inch rebar can also be used for stakes. • Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. Maintenance Standards • Wattles may require maintenance to ensure they are in contact with soil and thor- oughly entrenched, especially after significant rainfall on steep sandy soils. 2014 Stormwater Management Manual for Western Washington 1-1 Volume 11 - Chapter 4 - Page 377