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inundation from the old workings. The ] 00-foot buffer will be maintained by <br />advance drilling to find the location of the old workings. <br />Mine water inflow into the Sanborn Creek workings is estimated to be 425 gpm or <br />less. The old Somerset Mine had an inflow rate of 0.15667 gpm/acre for the 1,500 <br />acres of development in the mine that was below the level of the North Fork River. <br />Projecting this rate to the 2,600 acres of the Sanborn Tracts yields an inflow of 407 <br />gpm. The operator has rounded this figure to 425 gpm in the permit document. It is <br />not known at the time of this findings document what the source of the mine inflow <br />water was during the spontaneous combustion problem in 1999. The operator has <br />also projected an additional 235 gpm discharge from the old Somerset Mine, which <br />might reach the North Fork via the alluvial system. This is considered to be <br />extremely unlikely; however, the projection is used in the CHIS to allow for absolute <br />worst-case prediction. The following are potential sources for inflow: <br />The North Fork of the Gunnison River is 750 feet to the south and 100 feet <br />above the proposed B-seam workings and 40 feet above the C-seam workings. <br />Groundwater is expected to travel downdip from the river through the coal and <br />overburden into the mine workings. Because of the low permeability of the <br />coal and overburden, calculations have shown that these flows should be minor. <br />The flows can be expected to occur with a considerable lag time. There will be <br />a comparable diminution of flow in the North Fork but mine pumpage will <br />return this amount to the river, minus that used in the mine. The cone of <br />depression from dewatering of the strata will only extend to the boundary of the <br />North Fork and will not adversely impact any wells. <br />2. There is the potential that the mine may encounter water inflow from faults and <br />fractures. The location of these faults is unknown. The largest fault that the <br />old Somerset Mine encountered had a sustained inflow of 120 gpm, which <br />contributed 50 percent of the total inflow. The Somerset Mine has committed <br />to conducting a study of the potential for mine inflow from the faults and <br />fractures in the Coal Gulch area. <br />3. The Sanbom Creek workings will undermine portions of two abandoned mines <br />- the Oliver Mine and the Hawk's Nest Mine. The Oliver Mine was mined in <br />the 1930's and is known to be completely flooded. An exposure of the <br />workings adjacent to the old county road is discharging water at a rate of a few <br />gallons per minute. About 90 percent of the workings of this mine lie downdip <br />of the discharge point. <br />The Hawk's Nest Mine lies north of the Oliver Mine and is stratigraphically <br />higher than the Oliver D seam. Hawk's Nest mined in both the E and F seams. <br />The workings of this mine are probably not flooded, as indicated by <br />measurements in an old drill hole. Also, during operation of the Hawk's Nest <br />21 <br />