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<br /> <br />STATE OF COLORADO <br />DIVISION OF MINERALS AND GEOLOGY <br />Department of Nalu rat Resources <br />1 413 Sherman SI , Room 215 <br />Denvcr, CO 80203 <br />Phone: 13031 866-3567 <br />FAx: UO-t) 8328106 <br />August 20, 1993 <br />Mr. Mark Kerr <br />Operations Manager <br />Landmark Reclamation, Inc. <br />4901 South Windermere Street <br />Littleton, CO 80120 <br />RE: Rimrock Strip Mine, Permit No. C-89-074, Rimrock Coal Company, TR-03, <br />Adequacy Questions <br />Dear Mr. Kerr: <br />OF'~~(O <br />se a <br />~~ b <br />~a <br />• ,B,s g. <br />Roy Romer <br />Governor <br />M~chael8 Long <br />Division Director <br />The Division has reviewed the TR-03 submittal concerning the SAE demonstration <br />and the topsoil sediment control system and have the following questions or <br />comments: <br />1. Topsoil containment sumps are not considered impoundments. <br />Therefore, only the 10 year - 24 hour precipitation event is needed <br />for the design of the total containment topsoil sump. The <br />submittal used the correct 3.0 inches but mis-identified it as a 25 <br />year event instead of the 10 year event. <br />2. Is there any disturbance outside the permit area along Short Street <br />and, if so, has it been reclaimed? <br />3. In the field, what separates the west side of the SAE drainage <br />basin from the east side of the pond drainage basin? <br />4. The hydrology designs that were submitted use 3.0 inches of <br />precipitation for the 25 year - 24 hour event. However, the NOAA <br />atlas shows that 3.4 inches is more appropriate. Please resubmit <br />the SAE sump design using the 3.4 inches. <br />5. For the topsoil stockpile hydrology designs, an area of .89 acres <br />is used as the drainage area. However, there is additional runoff <br />from areas above the topsoil area that is not being diverted. <br />Please explain how the upland area runoff will be diverted. <br />6. For the SAE demonstration, how is the upland runoff above the haul <br />road being diverted from the SAE? <br />7. Please provide the equation used in this submittal for calculating <br />the peak discharge from the time of concentration. <br />