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• -3- • Ground water near the proposed mine has been developed for irrigation, stock-watering, and light industrual purposes. As discussed above, most of this water comes from the glacial/alluvial aquifer. Ground water is not used extensively for domestic purposes. Most domestic water comes from the town of Colby's domestic water system. A listing of existing wells in the area is presented in Table 2 of the addendum (Kimball, et al ., 1982). Probable Hydrologic Consequences of Mining The proposed mining operations will probably impact hydrologic conditions in the D seam, E seam, and the glacial/alluvial aquifers. Both the piezometric surfaces and water quality of the aquifers may be affected to some degree. The applicant's discussion of probable hydrologic consequences is contained in Section IV of the addendum to the application (Kimball, et al ., 1982). The following is a summary of that discussion. The dewatering of the mine workings will cause piezometric surfaces to lower in the vicinity of the mine. The aquifers that may be affected are the two coal seams and the glacial/alluvial aquifer. The applicant has predicted future mine inflows and resultant water level drawdowns through modeling techniques developed by McWhorter (1981). These predictions are presented in Table 8 of the application addendum. Total inflows to Each of the mines will average about 25 gpm. These predictions compare favorably with existing inflow conditions in the E seam mine. Distances down-dip from the mine. from which drawdowns will be noticeable are predicted to be 11.5 and 3.9 miles for thb D and E seams, respectively. The results of the modeling suggest that the drawdown will not extend out to the glacial/alluvial aquifer via the coal subcropa. The implications of these effects to waterusers in the area are considered to be insignificant. No wells in the area to be affected by the drawdowns are completed solely in the D or E coal seams. In addition, the dip of the strata causes the coal seams to become deeper and more inaccessible down-dip of the mine, Rt the farthest extent of the predicted drawdowns, the seams are probably several thousand feet deep. Therefore, the resultant impact produced. by the mine's dewatering practices is considered to be insignificant. It should be noted that these predictions assume that significant subsidence or fault induced inflows do not occur. No major faults have been identified in the mine_area. The applicant's limited coal extraction mettx~d should prevent significant subsidence. Therefore, it is considered reasonable to assume that subsidence and faults will not cause significant inflow problems in the mine.