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CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br />4. Topsoil shall not be placed while in a frozen or muddy condition, when the subgrade is <br />excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or <br />proposed sodding or seeding. <br />5. Previously established grades on the areas to be topsoiled shall be maintained according to the <br />approved plan. <br />6. When native topsoil is to be stockpiled and reused the following should apply to ensure that the <br />mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: <br />a. Topsoil is to be reinstalled within 4 to 6 weeks <br />b. Topsoil is not to become saturated with water <br />c. Plastic cover is not allowed. <br />Maintenance Standards <br />Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. <br />3.2.13 BMP C126: Polyacrylamide for Soil Erosion Protection <br />Purpose <br />Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. <br />Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment <br />in two ways. First, PAM increases the soil's available pore volume, thus increasing infiltration through <br />flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of <br />suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving <br />water quality. <br />Conditions of Use <br />l . PAM shall not be directly applied to water or allowed to enter a water body. <br />2. Some PAMs are more toxic and carcinogenic than others. Only the most environmentally safe <br />PAM products should be used. <br />3. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in <br />any application because of known aquatic toxicity problems. Only the highest drinking water <br />grade PAM, certified for compliance with ANSINNSF Standard 60 for drinking water treatment, <br />shall be used for soil applications. PAM use shall be reviewed and approved by the City. The <br />Washington State Department of Transportation (WSDOT) has listed approved PAM products on <br />their Web site. <br />4. In areas that drain to a sediment pond, PAM can be applied to bare soil under the following <br />conditions: <br />a. During rough grading operations <br />b. Staging areas <br />c. Balanced cut and fill earthwork <br />d. Haul roads prior to placement of crushed rock surfacing <br />e. Compacted soil roadbase <br />f. Stockpiles <br />g. After final grade and before paving or final seeding and planting <br />Volume 11 — Construction Stormwater Pollution Prevention <br />3-22 <br />