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Source of Water Inflow <br />As detailed in previous reports. the water flowing into the mine <br />seems to be a mix of water infiltrating the graben along the <br />faults and that water which is stored in the coal seam. The zone <br />of saturation of the coal seam was initially estimated using the <br />results of exploration drilling. The drilling indicated that <br />holes in the McClane graben were dry; specifically. holes 7-15-3 <br />and 7-21-1. Additionally. a piezometer installed downdip from the <br />mine has not realized water to date. Since the well is down-dip <br />and is dry. Salt Creek surmises that the water flowing into the <br />mine may be from a perched aquifer in the area of the coal mine. <br />The balance of the water flowing into the mine probably comes from <br />surface water infiltration along the faults east and west of the <br />mine. This assumption is supported by the cyclical nature of <br />water inflow corresponding with periods of precipitation. Figure <br />2, a graph of discharges from the mine vs. precipitation, shows <br />that more water is discharged from the mine during spring and fall <br />when the amount of run-off is highest. Both faults have ephemeral <br />drainages crossing their surface trace near the mine and may <br />receive water from the drainages. It is conceivable that these <br />faults may also prove to be the source of water For the perched <br />aquifer in the McClane graben. <br />If surface water infiltration were the only source of water, it <br />could be expected that the amount of water discharged from the <br />mine would be dependent on the amount of precipitation received <br />during the year. As Figure 1 shows. the amount of water being <br />discharged from the mine has decreased each year and was about <br />50,000 gallons a month during the last year. Apparently a <br />drawdown cone is being created around the area of the mine in the <br />perched aquifer. <br />Probable Nvdrologic Consequences <br />The McClane Canyon Mine seems to be dewatering a local perched <br />aquifer whose extent is not known. This bedrock aquifer has <br />tittle if any direct communication with the alluvial sediments <br />near McClane Canyon and would not contribute significantly to the <br />amount of water in these sediments as the formation dips away from <br />them. Any contribution could only occur if the perched aquifer <br />were filled to capacity. At capacity the aquifer would likely <br />discharge water in the form of a spring or seep at the lowest <br />point of contact with the surface or possibly sediments. The <br />lowest point of contact occurs in the North split of McClane Creek <br />near the place where Salt Creek 1s discharging water accumulating <br />in the mine. <br />Page -2 11/16/88 <br />