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feet. The subsidence projections and evaluation of potential related effects on the designated Fish Creek AVF are <br />documented in Exhibits 7B, 7C, 45, and 46. <br />During initial mining of Panel 6, Well GWB-2 was subsided, as predicted, and the well was damaged and <br />subsequently replaced. A replacement well (GWB-2R) was installed adjacent to the existing well. Well GWB-2R <br />was constructed adjacent to the existing well as a two-inch well with Schedule 80 PVC. The well completion <br />report was forwarded to the Division. The two wells were monitored for water levels twice per week for a two <br />week period, thereafter only Well GWB-2R will be monitored per the schedule presented on Table C of Exhibit 14. <br />Well GWB-2 was sealed with Volclay and permanently abandoned. Prior to permanently abandoning well GWB-2, <br />the Division inspected the well and provided Twentymile Coal Company with approval for well abandonment. <br />Originally, it was anticipated that room and pillar mining would be required to augment longwall production. <br />Given, however, the productivity, efficiency, and higher recovery for the longwall mining system, the need no <br />longer exists to identify a room and pillar area on [he east side of the North Mains. As shown on Maps 23, and <br />23A, an additional longwall panel is planned to the east of the North Mains. <br />Approximately 60,000 feet of mains are expected to be driven during the life-of--mine. <br />Areal Extent <br />The permit area of the underground mine, totals approximately 21,720 acres, of which approximately 9,000 acres <br />have been affected, with approximately another 1,920 acres to be affected under the currently approved mine plans. <br />These areas contain all mineable coal reserves bordered by the I S percent gradient cutoff line to the east and west <br />and the property line to the south. At the conclusion of mining, approximately 65 percent of all the coal contained <br />within the mineable reserve area will have been extracted (see Maps 7, 8, 9, 9a and Figure 1, Geologic Cross- <br />Sections A-A' through E-E'). <br />Minine Lavout <br />The underground mine layout was designed with the objective of rapid development, optimum access to outlying <br />reserves and maximizing recovery and safety. Numerous physical, geotechnical and operational variables <br />influenced design of the mining layout. <br />Mining activities are bordered on the east and west by ]ease boundaries, to the south by a lease boundary and <br />mined-out reserves, and to the north by a 15 percent seam gradient cutoff limit. Reserve access is by a network of <br />main entries oriented primarily north-south and east-west. Longwall panels are planned wherever geologically <br />possible and consistent with safe and prudent mining practices. <br />The following factors influenced the layout of the underground mine: <br />Lease Boundaries -Limits the extent of mining extension <br />Geotechnical Characteristics -Including rock and coal strengths, jointing, cleating and quality <br />Structural Features -Major fault zones and steep gradients are avoided or crossed selectively <br />Reserve Access -Minimal development and capital cost and optimum men and materials transport <br />Orientation -Mains, sub-mains and panels are oriented to avoid directions that have the potential for <br />instability <br />Water -Inflow and control has been considered through sump location and up-dip development <br />Subsidence -Controlled subsidence is planned over areas of full seam coal extraction <br />PR06-07 2.05-13 12/05/06 <br />