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• General characteristics of the strata: The coal seam dips to the west up to 20 degrees. The <br />overburden material consists mainly of thin io thick sandstones and is interbedded with <br />shales, siltstones, and thin and thick coal seams. <br />3.0 HYDROLOGY <br />3.1 GROUND WATER <br />The proposed highwall miner will remove a small portion of the Wadge/WOIf Creek seams in comparison <br />to mining that has already occurred upgradient. The existing monitoring wells will be used to monitor <br />for any measurable ground water impact throughout the life of the mining operation. Any additional <br />impacts to the down gradient Wadge/Sage Creek/Wolf Creek aquitersfrom the highwall mining will be <br />negligible lunmeasurable) Tor the following reasons: <br />1. The total area of additional disturbance is quite small in comparison to the surface mined areas. <br />2. The Wadge/Sage Creek/Wolf Creek coals have very low transmissivities. <br />3. The previously mined dragline pits have had minimal pit pumping, therefore SCC is anticipating <br />very small quantities of additional discharge caused by the highwall miner operations. Any <br />necessary pit dewatering activities will follow the procedures described in Tab 73. <br />4. No toxic-forming or acid-forming water discharge is anticipated from the highwall openings. <br />lReler to Tab 7, Hydrologic Description) However, if toxic-forming or acid-forming water <br />discharge is encountered, the opening of discharge will be backfilled within 72 hours after <br />completion. <br />5. The premining ground water flow should reestablish itself following backfilling of the final pit <br />areas that has been highwall mined. <br />3.2 SURFACE WATER <br />Surface water quantity and quality should not be affected by the highwall miner mining operation since <br />drainage will be handled in the same manner as existing final highwall stripping conditions. The <br />postmining reclaimed surface will be blended with the surrounding spoils and topography. The surface <br />will be revegetated in accordance with the approved revegetation plan. Should subsidence occur, <br />• surface drainage will not be adversely aff ecf ed as no postmining drainage will course over the proposed <br />highwall miner area. <br />D....:....,~ nA !!lA <br />