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• <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Natural Resources <br />1311 Sherman St., Room 215 <br />Denver, CG 80.07 <br />Phone. 130 71 866-3 567 <br />FA%: 13031 R3?8106 <br />February 18, 1993 <br />Darry Ferguson <br />Pioneer Engineering <br />3375 S. Bannock #210 <br />Englewood, CO 80110 <br />STATE OF CC~~ORADO <br />OF ~~t0 <br />~~~:i <br />~tBT6 ~• <br />Roy Romer <br />Governor <br />Michael B. Long <br />Division Director <br />RE: Carbon Junction Mine Adequacy Review (C-92-080) <br />Dear Mr. Ferguson: <br />Attached are the Division's adequacy responses to your December <br />10 and January 14, 1993 revision submittals. Several new issues <br />have been identified with the inclusion of the proposed gravel <br />pit operations within the boundaries of the coal mine permit <br />area. Additionally, it was noted that the sizing of ditches, <br />culverts, and sediment ponds were based upon erroneous <br />information contained in TR-55 and Peak Flows in Colorado. <br />Oakridge Energy will need to verify and/or redesign several of <br />the sediment control structures based upon the 100, 25, and 10 <br />year, 24 hour events published in the NOAA atlas for Colorado. <br />The precipitation amounts for the Type II 24 hour storms are as <br />follows: <br />100 year event - 3.75" <br />25 year event - 2.80" <br />10 year event - 2.25" <br />Further issues concerning ground water, vegetation, and how the <br />gravel pit operations may/will affect reclamation, sediment <br />control, and bonding costs are included. <br />Due to the complex and varied issues involved with the <br />combination coal mine and gravel pit operations, the Division <br />will extend the decision date for this new application to <br />April 1, 1993. <br />If you have any questions, please do not hesitate to contact me. <br />Sincerely, <br />~ ~~ ~ <br />Harry Ranney <br />Reclamation Specialist <br />