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Sufficient information is available to qualitatively project the potential <br />cumulative ground water impacts in the general area of the Foidel Creek Mine <br />upon several different aquifers while taking local structure into account. <br />The Twentymile sandstone aquifer, Middle Coal Group aquifer, the Trout Creek <br />sandstone aquifer and the various alluvial aquifers crossing the general area <br />may be cumulatively affected by mining. Mining would not affect the Tow Creek <br />sandstone. <br />Twentymile Sandstone <br />Ground water in the Twentymile sandstone aquifer may be cumulatively impacted <br />by spoil waters from the Seneca II Mine and the reclaimed CYCC N0. 2 Mine. <br />The portion of the Seneca II Mine within the Fish Creek drainage is <br />geographically located above the outcrops of the Twentymile sandstone. <br />Discharges of spoil water from the mine may recharge this aquifer. The amount <br />of spoil water discharge is expected to be insignificant, so impacts to ground <br />water quality will be minimal. Mine No. 2 is located in strata above the <br />Twentymile sandstone. Through deep percolation, spoil waters from the No. 2 <br />Mine recharge the Twentymile sandstone and impact water quality. There is <br />sufficient aquifer thickness and distance between the discharge point and the <br />mine to provide sufficient dilution: <br />The other mines in the Twentymile Park Basin are not expected to impact the <br />quality and quantity of ground water in the Twentymile sandstone. The other <br />mines are within the Middle Coal Group, which is separated from the Twentymile <br />sandstone by 600 to 700 feet of shale. Because of this separation, they are <br />not expected to affect the Twentymile sandstone. <br />Middle Coal Group Aquifers: <br />Wadge Overburden and Wolf Creek Overburden <br />The Edna, Seneca II (Fish Creek portion), and the CYCC Mines No. 1 and No. 3, <br />Eckman Park, Middle Creek, and Foidel Creek Mine will all impact the quality <br />and quantity of ground water within the Middle Coal Group of the Mesaverde <br />Group. All of these mines, except for the Middle Creek Mine, are located in <br />the recharge zones of these aquifers. <br />During mining, the quantity of ground water in the Middle Coal Group will be <br />depleted by both surface and underground mines. Surface mines in the general <br />area diminish the quantities of ground water recharge by pumping ground water <br />accumulating within the pit to surface stream, or by consuming ground water in <br />the mine's operation. Underground coal mines in the general area will <br />diminish the quantities of ground water stored within the aquifers by <br />dewatering these aquifers as mining progresses downdip {i.e., the mines will <br />act as large water wells). Surface coal mines will diminish ground water flow <br />rates within the aquifer during and shortly after operation, whereas <br />underground mines will primarily change the ground water flow direction within <br />the aquifers towards the mine workings. Both of these effects will deplete <br />ground water discharge from the Twentymile Park Basin. This depletion will <br />continue after mining has ceased until the spoils or the mine workings have <br />filled with water to a pre-mining or an equilibrium level. <br />-53- <br />