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pt <br /> ' entering the buffer,or additional perimeter protection must be <br /> installed. <br /> j <br /> BMP C235: Wattles <br /> { Purpose Wattles are temporary erosion and sediment control barriers consisting of <br /> straw, compost, or other material that is wrapped in biodegradable tubular <br /> I <br /> I plastic or similar encasing material. They reduce the velocity and can <br /> spread the flow of rill and sheet runoff,and can capture and retain <br /> sediment. Wattles are typically 8 to 10 inches in diameter and 25 to 30 feet <br /> in length. Wattles are placed in shallow trenches and staked along the <br /> 4 contour of disturbed or newt constructed slopes. See Figure 4.2.14 for <br /> � Y P g <br /> typical construction details. WSDOT Standard Plan 1-30.30-00 also <br /> provides information on Wattles <br /> (littp://www.wsdot.wa.gov/Design/Standards/Plans.htm##Sectionl) <br /> Conditions of Use Use wattles: <br /> r In disturbed areas that require immediate erosion protection, <br /> } <br /> On exposed soils during the period of short construction delays,or <br /> over winter months. <br /> 9 i t <br /> On slopes requiring stabilization until permanent vegetation can be <br /> established. <br /> • The material used dictates the effectiveness period of the wattle. <br /> Generally, Wattles are typically effective for one to two seasons. <br /> r . Prevent rilling beneath wattles by properly entrenching and abutting <br /> wattles together to prevent water from passing between theirs. <br /> r <br /> Design Criteria • Install wattles perpendicular to the flow direction and parallel to the <br /> t ! slope contour. <br /> • Narrow trenches should be dug across the slope on contour to a depth <br /> t i of 3-to 5-inches on clay soils and soils with gradual slopes. On loose <br /> is <br /> i A soils, steep slopes,and areas with high rainfall,the trenches should be <br /> R dug to a depth of 5- to 7- inches, or 1/2 to 2/3 of the thickness of the <br /> x <br /> wattle. <br /> Start building trenches and installing wattles from the base of the slope <br /> E { , and work up. Spread excavated material evenly along the uphill slope <br /> and compacted using hand tamping or other methods. <br /> • Construct trenches at intervals of 10- to 25-feet depending on the <br /> steepness of the slope, soil type, and rainfall. The steeper the slope the <br /> closer together the trenches. <br /> • Install the wattles snugly into the trenches and abut tightly end to end. <br /> Do not overlap the ends. <br /> • Install stakes at each end of the wattle, and at 4-foot centers along <br /> entire length of wattle. <br /> Vohtnie H—Construction Stornnwater Pollution Prevewion-August 2012 <br /> 4-95 <br />{F <br /> p F <br />