Laserfiche WebLink
Stormwater PoUution Prevention Plan <br />The construction dewatering water known to be free of contamination will trigger BMPs to trap <br />sediment and reduce turbidity. At minimum, geotextile filter fabric socks/bags/cells will be used <br />to filter this material. Other BMPs to be used far sediment trapping and turbidity reduction <br />include the following: <br />• Interceptor Dike and Swale (BMP C200) <br />• Silt Fence (BMP C233) or Straw Wattles (BMP C235) <br />Portable Water Storage Tanks (e.g. Baker Tank) for Sedimentation <br />Highly turbid dewatering water form soils known or suspected to be contarninated, or from use <br />of construction equipment, will require additional monitoring and treatment or off-site disposal <br />as required for the contaminants of concern. Monitoring is the responsibility of the contractor as <br />described in Section 6.2. <br />If encountered, BMPs to be used for treatment of potentially contaminated dewatering water <br />include: <br />• Construction Stormwater Filtration (BMP C251). Not anticipated at this time. <br />Construction Stormwater Chemical Treatment (BMP C250). Not anticipated at <br />this time and implemented only with prior written approval from Ecology. <br />Per the geotechnical report prepared by Hart Crowser on March 4, 2015, groundwater was not <br />encountered during subsurface investigation. Dewatering of groundwater is not anticipated as <br />part of the project. <br />Alternate dewatering control BMPs are included in Appendix C as a quick reference tool for the <br />onsite inspector in the event the BMP(s) listed above are deemed ineffective or inappropriate <br />during construction to satisfy the requirements set forth in the General NPDES Permit (Appendix <br />D). To avoid potential erosion and sediment control issues that may cause a violation(s) of the <br />NPDES Construction Stormwater permit (as provided in Appendix D), the Certified Erosion and <br />Sediment Control Lead will promptly initiate the implementation of one or more of the <br />alternative BMPs listed in Appendix C after the first sign that existing BMPs are ineffective or <br />failing. <br />3.1.11 Element #I 1— Maintain BMPs <br />All temporary and permanent erosion and sediment control BMPs shall be maintained and <br />repaired as needed to assure continued performance of their intended funetion. Maintenance and <br />repair shall be conductcd in accardancc witt� each particular BMPs specifications. Visual <br />monitoring of the BMPs will be conducted at least once every calendar week and within 24 l�ours <br />�� <br />