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DEPARTMENT OF NATURAL RESOURCES III III III IIIIIII III David H. Getcnes, Executive Director MINED LAND RECLAMATION DIVISION DAVID C. SHELTON, Director Richard D. Lamm Governor September 5, 1985 Larry M. Reschke, P.E. Mine Engineer Grand Mesa Coal Company P.O. Box 226 Delta, Colorado 81416 RE: Annual Hydrology Report and Request for Reduction in Monitoring File No. C-034-81 Dear Mr. Reschke: The Division has completed its review of Grand Mesa Coal Company's Annual Hydrology Report for the 1984 water year and the accompanying request for a reduction in existing monitoring requirements. The following comments detail the Division's interpretation of the hydrology report and recommendations for modifications to existing surface and groundwater monitoring requirements at the Red Canyon Mine. I. STATUS OF MONITORING SITES The following is a brief summary of the Data presented in the AHR. A. Ground Water - The coal seam piezometers (D-1, 2, 3; E-1, 2, 3; and F-1) show no remarkable change. Changes in water levels in these piezometers over the course of the year is most likely due to the heavy precipitation of the last few years. The above average amount of precipitation has generally caused the water levels to rise. Shallower holes, especially F-1, show normal seasonal fluctuations in water level. The 'D'~ Seam water appears to be high in Total Dissolved Solids (TDS) (specific conductivity of 3,000 to 4,000) and is sodium-bicarbonate in nature. This water is surprisingly low in sulfate (11.0 mg/1). The pH of this water is basic, ranging from 8.6 to 8.9. Field parameters taken of 'E' Seam water indicate a lower TDS value (SC = 850 to 1,050) than the 'D' Seam. A 1983 full suite analyses of this water shows it also to be sodium-bicarbonate, with little sulfate (6.0 mg/1). This water is also basic, with its pH varying between 8.1 and 8.3. 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303) 866-3567