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' areas shall drain to a sediment pond. . Areas less than 5 acres shall drain to sediment control BMPs, such as a minimum ' of 3 check dams per acre. The total number of check dams used shall be max- imized to achieve the greatest amount of settlement of sediment prior to dis- charging from the site. Each check dam shall be spaced evenly in the drainage ' channel through which stormwater flows are discharged off-site. . On all sites, the use of silt fence shall be maximized to limit the discharges of sed- iment from the site. . All areas not being actively worked shall be covered and protected from rainfall. PAM shall not be the only cover BMP used. . PAM can be applied to wet soil, but dry soil is preferred due to less sediment loss. . PAM will work when applied to saturated soil but is not as effective as applications to dry or damp soil. ' . Keep the granular PAM supply out of the sun. Granular PAM loses its effectiveness in three months after exposure to sunlight and air. . Proper application and re-application plans are necessary to ensure total effect- iveness of PAM usage. . PAM, combined with water, is very slippery and can be a safety hazard. Care must ' be taken to prevent spills of PAM powder onto paved surfaces. During an applic- ation of PAM, prevent over-spray from reaching pavement as pavement will become slippery. If PAM powder gets on skin or clothing,wipe it off with a rough towel rather than washing with water-this only makes cleanup messier and take longer. . Some PAMs are more toxic and carcinogenic than others. Only the most envir- onmentally safe PAM products should be used. ' 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, will be used for soil applications. Recent media attention and high interest in PAM has resulted in some entrepreneurial exploitation of the term "polymer." All PAM are polymers, but not all polymers are PAM, and not all PAM products comply with ANSI/NSF Standard 60. PAM use shall be reviewed and approved by the local permitting authority. ' . PAM designated for these uses should be "water soluble" or"linear" or"non-cross- linked". Cross-linked or water absorbent PAM, polymerized in highly acidic (pH<2) conditions, are used to maintain soil moisture content. . The PAM anionic charge density may vary from 2-30 percent; a value of 18 percent 2014 Stormwater Management Manual for Western Washington ' Volume II- Chapter 4 -Page 303