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~~i ri~riillirii rii STATE OF COLORADO Roy Romer, Governor DEPARTMENT OF NATURAL RESOURCES MINED LAND RECLAMATION DIVISION DAVID C. SHELTON, Director DATE: July 20, 1987 T0: Susan Mowry FROM: Tom Schreiner RE: WEST ELK COAL COMPANY, MT. GUNNI$ON N0. 1 MINE, TECHNICAL REVISIONS FOR REDUCTION IN HYDROLOGIC MONITORING AND VARIANCE FROM 4 FOOT COVER RULE, FILE N0. C-80-007 I have reviewed the West Elk Coal Company (WECC) response to adequacy questions for both technical revisions recently submitted. I have one final question for each of the two revisions. With the resolution of these 2 items I believe the revisions may be approved without stipulations. Reduction in Hydrologic Monitoring The applicant (WECC) does not agree that wells, springs, and stream gauging stations previously installed and monitored need to have monitoring activities resumed at least 1 full year prior to expected impacts. I presume the subbasins in question are the Horse Creek, South Prong, and the Beaver Reservoir area. The applicant estimates that it may take as long as 10 years before mining will take place south of the Minnesota Creek watershed divide. Asa result of the possible long-term gap between current and future monitoring periods the Division requires that seasonal measurements (three times per year corresponding to the start of spring runoff, peak spring runoff, and fall low flow) of flow, pH, conductivity, temperature, total manganese, total iron, total dissolved solids, and total suspended solids be made prior to expected mining impacts. Variance From 4 Foot Cover Rule (Rule 4.10.4(4 In the "Evaluation of the potential of WECC Refuse to Spontaneously Ignite" the applicant mentions that two mine supply storage pads east of the Mt. Gunnison No. 1 Mine portals contain approximately 5,500 cubic yards of refuse material. The piles were constructed in 1984 and the 2:1 sideslopes reclaimed with soil material to a depth of about 12 inches. No evidence of spontaneous combustion or significant erosion has been recorded for the 2 piles. Somewhere in the WECC or Mined Land Reclamation Division files there should be a justification for putting down only 12 inches of soil material versus a 4 feet cover over the 2 piles. That justification should be located and should be included in the file for Technical Revision No. 53 as supporting information for the variance from Rule 4.10,4(4). srs 1136E 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567