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Check dams may be installed in temporary ditches to minimize channel velocities and provide <br /> opportunity to settle out sediment as needed. <br /> Alternate channel and outlet stabilization BMPS are included in Appendix C as a quick reference tool for <br /> the on-site inspector in the event the BMP listed above is deemed ineffective or inappropriate during <br /> construction to satisfy the requirements set forth in General NPDES permit(Appendix D).To avoid <br /> potential erosion and sediment control issues that may cause a violation of the NPDES Construction <br /> Stormwater permit,the Certified Erosion and Sediment Lead will promptly initiate the implementation <br /> of one or more of the alternate BMPs listed in Appendix C after the first sign that existing BMP are <br /> ineffective or failing. <br /> The project site is located west of the Cascade Mountain Crest. As such, all temporary on-site <br /> conveyance channels shall be designed, constructed,and stabilized to prevent erosion from the <br /> expected peak 10-minute velocity of flow from a Type 1A, 10-year, 24-hour recurrence interval storm for <br /> the developed condition. Alternatively,the 10-year, 1-hour peak flow rate indicated by an approved <br /> continuous runoff simulation model, increased by a factor of 1.6, shall be used. Stabilization, including <br /> armoring material,adequate to prevent erosion of outlets, adjacent streambanks,slopes, and <br /> downstream reaches shall be provided at the outlets of all conveyance systems. <br /> 3.1.9 Element#9—Control Pollutants <br /> All pollutants, including waste materials and demolition debris,that occur on-site shall be handled and <br /> disposed of in a manner that does not cause contamination of stormwater. Good housekeeping and <br /> preventative measures will be taken to ensure that the site will be kept clean,well-organized, and free <br /> of debris. If required, BMP to be implemented to control specific sources of pollutants are discussed: <br /> BMP C151: Concrete Handling <br /> Vehicles,construction equipment, and/or petroleum product storage/dispensing: <br /> • All vehicles, equipment,and petroleum product storage/dispensing areas will be inspected <br /> regularly to detect any leaks or spills, and to identify maintenance needs to prevent leaks of <br /> spills. <br /> • On-site fueling tanks and petroleum product storage containers shall include secondary <br /> containment. <br /> 11 <br />