3214 BROADWAY BROADWAY KINECT APARTMENTS 2021-08-11

• CITY OF EVERETT STORMWATER MANAGEMENT MANUAL ; • 4. Topsoil shall not be placed while in a frozen or muddy condition,when the subgrade is • excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • 5. Previously established grades on the areas to be topsoiled shall be maintained according to the • approved plan. • 6. When native topsoil is to be stockpiled and reused the following should apply to ensure that the • mycorrhizal bacterial, earthworms,and other beneficial organisms will not be destroyed: • a. Topsoil is to be reinstalled within 4 to 6 weeks • b. Topsoil is not to become saturated with water • c. Plastic cover is not allowed. Maintenance Standards • Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. • 3.2.13 BMP C126: Polyacrylamide for Soil Erosion Protection • Purpose • Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. • Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment • in two ways. First, PAM increases the soil's available pore volume, thus increasing infiltration through • flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of • suspended particles and aids in their deposition,thus reducing stormwater runoff turbidity and improving • water quality. Conditions of Use 1. PAM shall not be directly applied to water or allowed to enter a water body. • 2. Some PAMs are more toxic and carcinogenic than others. Only the most environmentally safe • PAM products should be used. • 3. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in • any application because of known aquatic toxicity problems. Only the highest drinking water • grade PAM, certified for compliance with ANSI/NSF Standard 60 for drinking water treatment, • shall be used for soil applications. PAM use shall be reviewed and approved by the City. The Washington State Department of Transportation(WSDOT)has listed approved PAM products on • their Web site. - i 4. In areas that drain to a sediment pond,PAM can be applied to bare soil under the following • conditions: a. During rough grading operations • • b. Staging areas • c. Balanced cut and fill earthwork • d. Haul roads prior to placement of crushed rock surfacing • e. Compacted soil roadbase • f. Stockpiles • g. After final grade and before paving or final seeding and planting • Volume It—Construction Stormwater Pollution Prevention • 3-22 • C •