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Page 24 of46 <br />b. Whcre necessary to comply with S9.D3.a., stormwater retention or detention <br />facilities shall be constructed as one of the first steps in grading. Detention <br />facilities shall be functional prior to construction of site improvements (e.g., <br />impervious surfaces). <br />c. If permanent infilhation ponds aze used for flow control during construction, these <br />facilities shall be protected from siltation during the constiuction phase. <br />4. Install Sediment Controls <br />a. Storm�vater runoff from disturbed azeas shall pass duough a sediment pond or other <br />appropriate sediment removal BMP, prior to leaving a consavction site or prior to <br />discharge to an infiltration facility. Runoff from fully stabilized azeas may be <br />discharged without a sediment removal BMP, but shall meet the flow contrnl <br />pedormance standard of S9.D.3.a. <br />b. Sediment control BMPs (sediment ponds, Vaps, filters, etc.) shall be constructed as <br />one of the first steps in grading. These BMPs shall be functional before other land <br />disturbing acti�+ities take place. <br />c. BMPs intended to trap sediment on site shall be located in a manner to avoid <br />interference with the movement of juvenile salmonids attempting to enter off- <br />channel areas or drainages. <br />5. Stabilize Soils <br />a. Exposed and unworked soils shall be stabilized by application of effective BMI's <br />that prevent erosion. Applicable BMPs include, but are not limited to: temporary <br />and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics <br />and matting, soil application of polyacrylamide (PAIvn, the early application of <br />gravel base on areas to be paved, and dust control. <br />b. Depending on the geographic location of the project, no soils shall remain exposed <br />and umvorked for more than the time periods set forth below to prevent erosion: <br />West of the Cascade Mountains Crest <br />During the dry season (May 1- Sept. 30): 7 days <br />During the wet season (October 1- April 30): 2 days <br />East of the Cascadc Mountains Crest, except for Central Basin' <br />Duriug the dry season (July 1- September 30): 10 days <br />During the wet season (October 1- June 30): 5 days <br />The Central Basin", East of the Cascade Mountains Crest <br />During the dry Season (July ]- September 30): 30 days <br />lluring the wet season (October 1- June 30): 15 days <br />'Note: The Central Basin is defined as the portions of Eastem Washington <br />with mean annual precipitation of less than 12 inches. <br />