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• However, because infiltration is so low, and ground water moves so slowly, it <br />will be hundreds of years before any degraded water would leave the minesite, <br />so there is no way of predicting if any wells would be affected. The <br />applicant has made a detailed analysis of anticipated infiltration into and <br />through the replaced spoils (p. 4-45 to 4-54 of the MRP). The results <br />indicate that it will be 740 years before percolating watfar from the spoil <br />will move into the ground-water system. Furthermore, the applicant has <br />committed to disposing of the waste at least 10 feet above the projected <br />postmining water table, and to cover it with at leas[ 5 feet of non-toxic <br />material. This should greatly reduce the chance of any leachate entering the <br />Bound-water system. <br />The applicant has several monitoring wells downgradient from the mine. The <br />program of regular water-quality sampling should detect any water-quality <br />changes that occur during the mining operations. Any change in water quality <br />would be temporary, as continued movement of water through the wastes and <br />spoils would flush out the poorer material, and water quality would gradually <br />return to normal. <br />It is possible that several hundred years after mining en.is, springs could <br />form in the spoil at the downgradient contact of the mined and unmined areas. <br />These springs initially would discharge poorer quality ground water into the <br />streams. Although this water would not be suitable for domestic purposes, it <br />would be suitable for livestock and wildlife watering (th~a only current uses <br />of water at the minesite). The poorer quality of water would rapidly be <br />diluted by better quality surface water, and any impacts would dissipate <br />downstream. <br />The applicant estimates that the post-mining infiltration capacity of the <br />replaced spoils would be about two orders of magnitude greater than that of <br />undisturbed soils. Since this would still be a low infiltration rate, mining <br />and reclamation should have little impact on recharge to the ground-water <br />system. <br />. -12- <br />