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• Tab 7 - Hvdrolocic Description 17. SCC has revised the following sections to document the failure of annular and bottom seals in certain monitoring wells: for Wells YOV1 and YOVB, "Wadge Overburden Water Levels"; for Well YW2, "Wadge Coal Water Levels"; and for Wells YLOV3 and 4 and YL5 and 6, "Introduction to Aquifer Characteristics". Since all well failures are sufficiently documented, SCC feels that high transmissivity values are not a result of fractured bedrock. 18. The potentiometric surfaces of the Wadge overburden, alluvium, Wadge coal, and Wadge underburden units depicted on Exhibits 7-2 through 7-4 were developed using the arithmetic mean of valid water levels (Table 7-3) collected during the baseline period. Water levels used are contained in Appendix 7-2. Detailed descriptions of water levels collected, including validity and seasonal variability, are presented by well for each geologic unit in the Baseline Ground Water Level section of Tab 7. Several short sentences have been added to pertinent paragraphs within the "Potentiometric Surfaces" section of Tab 7 (Pages 21 and 22) to provide further clarification regarding data used to develop each of the potentiometric surface maps (Exhibits 7-2 through 7-4). • Water levels used to construct the potentiometric surfaces were collected from monitoring wells at select frequencies approved by the CDMG. The horizontal extent of the local potentiometric surfaces depicted on the three exhibits is governed by the spatial distribution of the approved monitoring wells and geologic limitations imposed on each surface by local hydrogeologic boundaries. All three units crop out in the southern portion of the permit boundary, forming a "V" pattern of outcrop along the Fish Creek anticline. The potentiometric surfaces of the three bedrock units shown on the exhibits were truncated in the vicinity of these outcrops. Towards the north, the plunging Fish Creek anticline provides a local ground water flow divide, forcing flow to the northwest along the western flank, and to the northeast along the eastern flank. The Wadge overburden may provide some recharge component to the upstream reach of Sage Creek, yet downgradient, the stream and saturated alluvium exert only minimal influence on bedrock units at discharge boundaries since most units dip far below significant downgradient streams and associated alluvium. All units deepened extensively towards the northeast and northwest outside of the permit boundary. Rule 2.04.7(1)(a)(ij requires description, not definition, of the horizontal extent of the potentiometric surfaces. SCC • believes the potentiometric surfaces of the geologic units located above, within and below the coal seams at the Yoast Mine, have been adequately described, including the horizontal 3