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_pg_ <br />construct the Orchard Valley West Mine numerous exploration holes were <br />drilled. Of these holes 20 were cased and are used as piezometers or <br />monitoring wells. Pump tests were conducted on five of these wells located in <br />both the coal and colluvium and both show low permeabilities. Holes drilled <br />in the coal close to outcrop were dry; those drilled down dip away from the <br />outcrop encountered water and permeability tests indicated confined <br />conditions. Generally, the permeabilities in the co~luvium average 7.2 x <br />10-2 ft/day and in the coal the average is 1.4 x 10- ft/day. Based on <br />these permeabilities the applicant estimates that established inflows into the <br />mine due to the 5 entries will be 1.3 gpm. <br />The greatest potential for subsidence to have an effect on ground water is <br />within the stream channels containing deposits of alluvium and colluvium. Two <br />wells exist adjacent to the area which may be mined in the future and withdraw <br />water from stream alluvium, one in Steven's Gulch (used by CWI) and the other <br />to the north of the mine area east of the Morrell Cow Camp and near the Terror <br />Creek drainage (NW 1/2 NW 1/4, Section 6, T13S, R91W). This latter well is <br />located outside the area to be mined, and in an area where the overburden <br />depth is in excess of 1,500 feet. The Steven's Gulch well field, however, is <br />within the area which may be undermined over the life of the mine and has an <br />overburden depth of 660 feet. <br />The applicant will continue to providing a yearly inflow study under a <br />stipulation in the 1983 permit which has been revised as follows: <br />Stipulation No. 4 <br />THE OPERATOR SHALL CONTINUE TO SUBMIT TO THE DIVISION AN ANNUAL REPORT OF <br />INFLOWS, DISCHARGES, AND CONSUMPTION OF WATER WITHIN THE MINE. THIS <br />REPORT IS TO INCLUDE A MINE WORKINGS MAP SHOWING THE LOCATION AND <br />QUANTITY OF INFLOWS; A TABLE KEYED TO THE MINE MAP WHICH SHALL CONTAIN <br />THE SOURCE (I.E., FAULT, FRACTURES, ETC.), QUANTITY, DURATION AND QUALITY <br />(I.E., pH, ELECTRO-CONDUCTIVITY AND TEMPERATURE) OF ALL MEASURABLE <br />INFLOWS; A TABLE CONTAINING RECORDS OF WATER IMPORTED FOR USE WITHIN THE <br />MINE; A DISCUSSION OF THE WATER BALANCE WITHIN THE MINE; AND FINALLY, A <br />PROJECTION OF HYDROLOGIC IMPACTS OF MINING IN THE UPCOMING YEAR. THE <br />MINE INFLOW STUDY SHALL BE CONDUCTED DURING THE MONTH OF JUNE. IF THE <br />OCCURRENCE OF INFLOWS BECOMES SIGNIFICANTLY GREATER THAN THE ANTICIPATED <br />RATES, THE DIVISION MAY REQUIRE THAT AN ADDITIONAL INFLOW STUDY BE <br />CONDUCTED AT ANOTHER TIME DURING THE YEAR. <br />The total mine inflows presently encountered are insignificant and are <br />insufficient to meet the water requirements of the underground mine. The <br />Orchard Valley Mine has to import water to meet these requirements. During <br />the year 1983, approximately 8-10 million gallons of water were imported to <br />the mine for dust suppression (page 139A of Section 2.05.6 in Volume 16). In <br />atypical year the applicant calculated that 6.24 million gallons of this <br />imported water were consumed as moisture absorbed by the coal, approximately <br />0.5 million gallons were consumed through increased humidity in the <br />ventilation air, and less than 0.5 million gallons were lost through seepage <br />into the flood of the mine. <br />