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<br />-35- <br />One channel sandstone was encountered in the 1 P.S. workings which contributes <br />3 gpm. This channel sand is probably draining ground water from the coal seam. <br />Only one minor inflow was observed issuing from the mine floor. The rate of <br />inflow was estimated to be 1 gpm. This indicates that the Allen Mine is not <br />significantly impacting the quantity of ground water in underlying aquifers. <br />The major source of mine inflows measured in the Allen Mine are from seals <br />which close off old mined-out areas. The total quantity of mine inflows from <br />mined-out areas was measured to be 88 gpm. The total area which contributes <br />to these inflows is about 2800 acres. The calculated inflow rate per unit <br />area for the mined-out workings is 0.03 gpm/acre. The total inflow rates <br />measured for the mined-out areas would be the sum of the inflows from weeping <br />coal faces, subsidence-induced fractures, any unsealed drill hales in these <br />areas, and vertical leakance through overburden strata. The major source of <br />mine inflows in these areas is probably the weeping coal faces, resulting from <br />dewatering of the coal aquifer. Coal faces on the western edge of the Allen <br />permit boundary are near the coal seam aquifer recharge area. These workings <br />could quickly capture any recharge waters and channe]ize flows of water down <br />the dip of the coal seam to the seals, where the inflows were measured. <br />Weeping coal faces were also observed as a major source of inflow in the <br />Maxwell Mine. <br />Since the coal seam aquifer subcrops beneath Pete Canyon and the Middle Fork <br />of the Purgatoire River, the A11en Mine workings could be depleting water from <br />these stream/alluvial aquifer systems. The amount of water depleted should be <br />minimal, given the small subcrop areas under these stream/alluvial aquifer <br />systems. The .present depletion of surface flow and alluvial ground water flow <br />is minimal, since mine inflows are discharged back to the surface water <br />system. After mining ceases, water will be depleted from the stream/alluvial <br />aquifer systems which will not be returned. This depletion will persist as <br />the mine workings fill with water. Once the mine workings have filled, <br />surface flows and alluvial ground water flows should closely approximate the <br />flows which existed before mining occurred. <br />The applicant has provided a discussion of water quality effects of mine <br />discharges upon the Purgatoire River stream/alluvial aquifer system as a <br />result of the proposed mining activities at the Allen Mine. The water <br />discharged from the Allen Mine is a sodium-bicarbonate type water with an <br />average pH of 8.3, and an average total dissolved solids of 806 mg/1 (Exhibit <br />6, Table 5 of the Allen application). Under low flow conditions, this <br />discharge would increase the total dissolved solids in the river by 32 mg/1 <br />(Exhibit 6, Table 8). <br />At the Allen Mine site, several historic and existing coal refuse piles are <br />located on the alluvial floodplain of the Middle Fork of the Purgatoire <br />River. Seepage from the refuse piles enters the stream-alluvial aquifer <br />system where it can affect water quality. An analysis of leachate from the <br />Allen Mine waste pile (Exhibit 6, Table 13) shows this water to be a <br />sodium-sulfate, bicarbonate type water with a total dissolved solids <br />concentration of 2599 mg/1, and a pH of 8.0. Trace metal concentrations were <br />