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i <br /> i <br /> - k <br /> The Coal Creek drainage basin is approximately 26.6 square miles <br /> rj <br /> Y T <br /> (17,024 acres) in area, is roughly 8.4 miles long from its confluence <br /> with the Crystal River to the north-westerly corner of the basin, and <br /> varies in altitude from 7160 feet above mean sea level (msl) near <br /> h <br /> =4 <br /> Redstone to 11,850 feet msl on the western boundary. The elevation <br /> of the Preparation Plant Area is about 8200 feet msl. The average <br /> F <br /> 5 <br /> slope- of Coal Creek from the Preparation Plant to the Crystal River ? <br /> is about five feet in one hundred feet or a five percent slope. <br /> For purposes of the report, the Coal Creek basin was divided into c <br /> two study areas: the Road Systems Area and the Preparation Plant- - <br /> • Area. The Road Systems Area is shown on Plate I and the Preparation <br /> Plant Area is shown on Plate II. In the Road Systems Area approxi- <br /> mately 290 acres of land have been disturbed by the mining operation <br /> for portal areas, roads, spoil piles and other use areas. The Pre- <br /> paration Plant Area has a total use area of 48 acres. NOTE : The <br /> Road Systems Area study has been superc-eded by the MK Study <br /> covered in the preceding Attachment to this Appendix . - <br /> The Soil Conservation Service method of drainage and flood analysis <br /> was adopted as the best procedure for the Road Systems Area because <br /> of the relatively small percentage of developed area, the relatively <br /> large contributary drainage areas and the wide variation in runoff f <br /> characteristics due to topography, soil cover and type of soil. <br /> i <br /> The Preparation Plant Area contains eight small drainage areas, none <br /> of which exceed 11 acres in size. Because of the small size of each " <br /> 7 <br /> 1 <br />