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comply with Federal and State environmental and engineering <br /> standards . Since the drainage from all the disturbed areas in <br /> the permit area enters Coal Creek three or more miles before that <br /> creek enters the Crystal River, Coal Creek provides a check on <br /> the effectiveness of the hydrologic control plan. <br /> The design and construction of the drainage and <br /> sediment control system in Coal Basin has been accomplished on an <br /> area basis . Specific areas are the mine portal areas , haul road <br /> system, preparation plant area, coal refuse disposal area and <br /> tunnel project area. The drainage and sediment control plans <br /> -that have been developed and implemented for each of these areas <br /> are covered in detail in Appendix II-B-7 . <br /> b . Sedimentation pond design criteria . <br /> The removal of excess amounts of suspended solids <br /> from water flowing out of disturbed areas within the permit area <br /> is accomplished by retaining the outflow in a system of " 38 <br /> sediment ponds sufficient time for sedimentation to clarify the <br /> water (24 hour minimum) . Design standards for the ponds meet the <br /> requirement to convey and treat the projected runoff from the 10 <br /> year 24 hour storm event. In no instance is it anticipated that <br /> the effluent from the ponds will exceed a daily suspended solids <br /> concentration of 70 milligrams per liter (mg/1) nor a 30 consecu- <br /> tive day average of more than 35 mg/l (wet conditions = . 5 mg/L <br /> settleable solids) . The Coal Basin sediment pond system (See <br /> Table II-B-2 and Exhibit II-B-2 a thru d) is desig.ned for a 10 <br /> year/24 hour precipitation event. A limited number of small <br /> areas have CMLRB approved variances . Typical small areas are the <br />