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STATE OF COLORADO Roy Romer, Govei DEPARTMENT OF NATURAL RESOURCES MINED LAND RECLAMATION DIVISION DAVID C. SHELTON, Director February 3, 1987 Martin P. Holmes Manager Permits and Regulatory Compliance Kaiser Coal Corporation 102 South Tejon Street, Suite 800 P. O. Box 2679 Colorado Springs, Colorado 80901-2679 Re: Hydrologic Monitoring for the Somerset Mine, - File No. C-81-022 Dear Mr. Holmes: I have reviewed the 1986 third quarter hydrologic monitoring report, second quarter pond inspection and NPDES report, and October results for Monitoring Well H-10 for the Somerset Mine. The format used in the reports was good, information presented was well organized. A11 necessary correspondence with the Colorado Department of Health, with respect to the discharge from Sedimentation Pond No. 10 on September 22~ was found to be in order. The other review comments I have are in regard to mine workings water monitoring at Sites H-10 and B-6. The October monitoring results for Well H-10 indicate an extremely high concentration (1234 mg/1) of dissolved sodium. This concentration is in excess of receiving stream and drinking water standards. However, the October sodium concentration appears to be consistent with that of other mine water samples collected from 1980-1986 and with the August 25, 1980 roof and floor analysis. At present, our data suggests that the average annual concentration of dissolved sodium is 40 mg/1 for all North Fork Gunnison River Tributaries, 19 mg/1 for Hubbard Creek, and 430 mg/1 for Alluvial Ground Water Well WMW-1. These results indicate that local streams have low concentrations of dissolved sodium relative to the mine inflow water. The mine inflow water has a high concentration of dissolved sodium because of contact (percolation) with the strata near the coal seam and possibly because of contact with the mined "B" coal seam. Correspondence from Kaiser Coal Corporation dated June 6 and July 28, 1986 indicates that a new water management plan will be incorporated for future water monitoring at the Somerset Mine. Flooded mine workings will be monitored four times a year (April, June, August, October) at sites B-6 and H-10. A water quality analysis and report containing a mine workings plan map with five cross sections will be submitted to the Division after water monitoring for the calendar year is completed. The cross sections will compare the surface topography and coal seam with the water elevation measured at that point in time. The intent of the monitoring program for the flooded 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tel. (303) 866-3567