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2.0 GEOLOGY • <br />Site specific geology within and adjacent to the permit area is presented in Tab 6 of the permit <br />application package. <br />• Coal seams to be mined: Wadge and Wolf Creek <br />Wadge Thickness: T to 14' <br />Wolf Creek Thickness: 10' to 16' <br />Height of highwall: The highwall height will vary from 30' to 150'. The maximum <br />overburden depth encompassing the highwall miner will be approximately 450 feet. <br />• General characteristics of the strata: The coal seam dips to the west at 8 to ]2 degrees. The <br />overburden material consists mainly of thin to 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/Wolf Creek seams in <br />comparison to mining that has already occurred upgxadient. The existing monitoring wells will be <br />used to monitor for any measurable ground water impact throughout the life of the mining operation. <br />Any additional impacts to the down gradient Wadge/Wolf Creek aquifers from the highwall mining • <br />will be negligible (unmeasurable) for the following reasons: <br />7. The total area of additional disturbance is quite small in comparison to the surface mined <br />areas. <br />2. The Wadge/ Wolf Creek coals have very low transmissivities. <br />3. The previously mined dragline pits have had minimal pit pumping, therefore SCC is <br />anticipating very small quantities of additional discharge caused by the highwall miner <br />opexauons. Any necessary pit dewatering activities will follow the procedures described in <br />Tab 13. <br />4. The premining ground water flow should reestablish itself following backfilling of the fatal <br />pit 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 <br />since 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 <br />surface will be revegetated in accordance with the approved revegetation plan. Should subsidence <br />occur, surface drainage will not be adversely affected as no postmining drainage will course over the <br />propose highwall miner area. <br />• <br />t2-2-2 TR-21 <br />