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cover condition for predicting flow rates from tributary areas outside the <br /> project limits. For tributary areas on the project site,the analysis must use <br /> the temporary or permanent project land cover condition,whichever will <br /> produce the highest flow rates. If using the WWHM to predict flows,bare <br /> soil areas should be modeled as "landscaped area." <br /> ii. East of the Cascade Mountains Crest: Channels must handle the expected <br /> peak flow rate from a 6-month, 3-hour storm for the developed condition, <br /> referred to as the short duration storm. <br /> b. Provide stabilization, including armoring material, adequate to prevent erosion <br /> of outlets,adjacent stream banks, slopes, and downstream reaches at the outlets <br /> of all conveyance systems. <br /> 9. Control Pollutants <br /> Design,install,implement and maintain effective pollution prevention measures to <br /> minimize the discharge of pollutants.The Permittee must: <br /> a. Handle and dispose of all pollutants,including waste materials and demolition <br /> debris that occur on site in a manner that does not cause contamination of <br /> stormwater. <br /> b. Provide cover, containment, and protection from vandalism for all chemicals, <br /> liquid products,petroleum products, and other materials that have the potential <br /> to pose a threat to human health or the environment. On-site fueling tanks must <br /> include secondary containment. Secondary containment means placing tanks or <br /> containers within an impervious structure capable of containing 110%of the <br /> volume contained in the largest tank within the containment structure. Double- <br /> walled tanks do not require additional secondary containment. <br /> c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles <br /> using spill prevention and control measures. Clean contaminated surfaces <br /> immediately following any spill incident. <br /> d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment <br /> system that prevents discharge to surface water, such as closed-loop <br /> recirculation or upland land application,or to the sanitary sewer with local <br /> sewer district approval. <br /> e. Apply fertilizers and pesticides in a manner and at application rates that will not <br /> result in loss of chemical to stormwater runoff. Follow manufacturers' label <br /> requirements for application rates and procedures. <br /> f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying <br /> sources. The sources for this contamination include,but are not limited to: bulk <br /> cement,cement kiln dust, fly ash,new concrete washing and curing waters, <br /> recycled concrete stockpiles,waste streams generated from concrete grinding <br /> and sawing, exposed aggregate processes, dewatering concrete vaults, concrete <br /> Construction Stormwater General Permit <br /> Page 33 <br />