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velocity and peak volumetric flow rate of stormwater runoff from the project <br /> site,as required by local plan approval authority. <br /> b. Where necessary to comply with Special Condition S9.D.3.a, construct <br /> stormwater retention or detention facilities as one of the first steps in grading. <br /> Assure that detention facilities function properly before constructing site <br /> improvements(for example, impervious surfaces). <br /> c. If permanent infiltration ponds are used for flow control during construction, <br /> protect these facilities from siltation during the construction phase. <br /> 4. Install Sediment Controls <br /> The Permittee must design,install and maintain effective erosion controls and <br /> sediment controls to minimize the discharge of pollutants.At a minimum,the <br /> Permittee must design, install and maintain such controls to: <br /> a. Construct sediment control BMPs(sediment ponds,traps,filters, infiltration <br /> facilities, etc.)as one of the first steps in grading. These BMPs must be <br /> functional before other land disturbing activities take place. <br /> b. Minimize sediment discharges from the site. The design, installation and <br /> maintenance of erosion and sediment controls must address factors such as the <br /> amount, frequency, intensity and duration of precipitation,the nature of <br /> resulting stormwater runoff, and soil characteristics, including the range of soil <br /> particle sizes expected to be present on the site. <br /> c. Direct stormwater runoff from disturbed areas through a sediment pond or other <br /> appropriate sediment removal BMP,before the runoff leaves a construction site <br /> or before discharge to an infiltration facility. Runoff from fully stabilized areas <br /> may be discharged without a sediment removal BMP,but must meet the flow <br /> control performance standard of Special Condition S9.D.3.a. <br /> d. Locate BMPs intended to trap sediment on site in a manner to avoid interference <br /> with the movement of juvenile salmonids attempting to enter off-channel areas <br /> or drainages. <br /> e. Provide and maintain natural buffers around surface waters,direct stormwater to <br /> vegetated areas to increase sediment removal and maximize stormwater <br /> infiltration,unless infeasible. <br /> f. Where feasible,design outlet structures that withdraw impounded stormwater <br /> from the surface to avoid discharging sediment that is still suspended lower in <br /> the water column. <br /> 5. Stabilize Soils <br /> a. The Permittee must stabilize exposed and unworked soils by application of <br /> effective BMPs that prevent erosion. Applicable BMPs include,but are not <br /> limited to: temporary and permanent seeding, sodding,mulching,plastic <br /> covering, erosion control fabrics and matting, soil application of polyacrylamide <br /> Construction Stormwater General Permit <br /> Page 30 <br />