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i' <br />T_he~ feet Vertical oermeabilit~of the overburden materials is small <br />and vertical 1 aeaa ~ rhn mine_from the.surface__and ne_ ar surface wat <br />-~ in the valley is estimated to be less than 3 gpm in the absence of sum bs~ e. <br />This small quantity of flow will have a negligible effect on the quality, <br />quantity, and levels of water in the valley. <br />I <br />During active mining, the drawdawn of the piezometric surface will ex- <br />1 ~ `~ tend outward from the mine possibly as far as 15,000 ft., measured from the <br />center of the mine. Recovery of the piezometric surface to the post-minino <br />~ steady state levels will occur over approximately SO years, beginning with <br />the cessation of mining. Most of that time period is required to flood the <br />J mine workings. The past-mining distribution of piezometric head i_s expected <br />--- ---- <br />--~, to exhibit a permanent depression in the vicinity of the mine du e. to the <br />1 essentially infinite permeability of +n~worJciogs. The post-mining quality <br />of ground water passing out of the flooded mine probably xill be slightly reduced <br />relative to the undisturbed ground water. Based on the dip of the coat seam, <br />the plume of water of modified quality will move toKard the northeast _• <br />at a very slow rate. <br />~ The discharge of mine waters to the stream constitutes a small, temporary <br />change in the local hydrologic regime, both with respect to quantity and <br />quality. No permanent modifications of the recharge or discharge of ground <br />____3 <br />. water are expected. The post-mining pattern of flow in the vicinity of the <br />mine will be modified relative to the pre-mining condition insofeir as there <br />1' <br />will remain a "permanent" concentration of flow lines around the flooded <br />mine workings. <br />II <br />