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1. Qaortirarive /mpacrs of Mining <br />Groundwater <br />Groundwater monitoring information acquired in the last fourteen years at the New Elk and <br />Golden Eagle Mines consists of water level and water quality information from alluvial wells <br />and estimates of mine water inflows and discharges from the two mines. In addition, this report <br />will make use of water level data acquired in the last few months on historic holes at the site and <br />information acquired during drilling for exploration and degas well development. This report <br />will assess the degree of hydraulic communication between the mine and surface and near <br />surface waters in the valley. It will compaze the 1980 estimates on the drawdowns of the <br />piezometric surface and the subsequent recovery of the same, and the quantity of inflows with <br />data actually_ collected at the site. <br /> <br />Mapping of mine inflows has been performed annually and the results have been included in the <br />Annual Hydrology Reports. The stream channels in the area have been superimposed on these <br />maps, and inflows have definitively not been correlated with the expression of stream channels <br />in Apache Canyon, along the Purgatoire, in Ciruela Canyon, or in Santistevan and Zamora <br />Canyons. In addition, monitoring of flow within the streams is performed monthly, and trends <br />outside the annual seasonal variation have not been observed. Nine springs or seeps within one <br />mile of the New Elk and Golden Eagle permit boundaries have been monitored annually in late • <br />summer for ten years without showing any trends in their yield (Basin, 1994). <br />Waste, Water and Land (WWL) (1980) estimated the maximum inflows to the Maxwell (Golden <br />Eagle) Mine from roof and floor faces of the coal to be 120 gpm and 73 gpm respectively, <br />totalling 193 gpm. This estimate was based on room and pillar mining of a mine with an azeal <br />extent of 6 square miles (1.7 x 10$ ftz) and a perimeter of 4.6 x 10° ft. The mine plan currently <br />includes a substantial amount of longwall mining, an areal extent of 3.99 x 10' ft2, and a <br />perimeter of 3.5 x 10° ft. The acreage is 20% of the projected build-out and the perimeter is <br />77%a of the projected perimeter. This corresponds to an equivalent WWL worst case projection <br />of 85 gpmr. In 1993, Basin observed inflows at the Golden Eagle Mine of 208 gpm of which <br />74 gpm came from the roof and floors, 34 gpm came from leaks associated with drill holes and <br />Calculated using a transmissivity of 1.98 ft'-/day, a coal permeability of 2.1 z 10' ft/day, and an effective <br />thickness of the overburden (b~ of 225 ft. <br />B = (1.98 frZ/day x 225 ft ! .00021 ft/day)' = 1465 ft <br />q = (1.98 ftZ/day x 225 fr) /1465 ft = .304 ft'- /day <br />Inflow from the face = (.304 ft'-/ day x 35,000 ft)/1.92 ft'/day/gpm = 55 gpm <br />Inflow from the roof = (2.1 x 10' ft/day) x (2.8 z 10' ft2)/ 1.92 ft'/day/gpm =30 gpm <br /> <br />8 <br />