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2.1.10 Element 10: Control Dewatering <br /> Describe where dewatering will occur, including source of the water to be removed. State clearly <br /> if dewatering water is contaminated or has the potential to be contaminated. <br /> Water from foundations, vaults, and trenches with characteristics similar to stormwater runoff <br /> shall be discharged into a controlled conveyance system before discharging to a sediment trap <br /> or sediment pond. Clean dewatering water will not be routed through stormwater sediment <br /> ponds. <br /> Only clean, non-turbid dewatering water (such as well-point groundwater) may be discharged to <br /> systems tributary to, or directly into, surface waters of the State, provided the dewatering flow <br /> does not cause erosion or flooding of receiving waters. <br /> Describe how you will manage dewatering water to prevent the discharge of contaminants to <br /> waters of the State, including dewatering water that has comingled with stormwater (i.e., <br /> treatment system, off-site disposal). <br /> Only clean, non-turbid dewatering water (such as well-point groundwater) may be discharged to <br /> systems tributary to, or directly into, surface waters of the state, provided the dewatering flow <br /> does not cause erosion or flooding of receiving waters. Due to the contamination of the existing <br /> soils, all stormwater and incidental groundwater will be treated on site through a chitosan <br /> enhanced sand filtration (CESF) treatment system in accordance with the Administrative Order <br /> issued by Washington State Department of ecology. <br /> Check treatment of disposal option for dewatering water, if applicable: <br /> Table 4 — Dewatering BMPs <br /> ❑ Infiltration <br /> ® Transport off-site in a vehicle (vacuum truck for legal disposal) <br /> ® Ecology-approved on-site chemical treatment or other suitable treatment technologies <br /> ❑ Sanitary or combined sewer discharge with local sewer district approval (last resort) <br /> ❑ Use of sedimentation bag with discharge to ditch or swale (small volumes of localized <br /> dewaterin <br /> List and describe BMPs: <br /> A Chitosan enhanced sand filtration system will be used. This plan has been put together by <br /> Clear Water Compliance to treat the water that has been contaminated. A temporary sediment <br /> pond will be constructed or an existing sediment pond will be used to collect all the water from <br /> the spoil pile area to be treated through the Chitosan system. <br /> • Construction Stormwater Chemical Treatment (BMP C250) <br /> Page 127 <br />