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<br />above the seams), ba equal to 100 ft and Ka equal to 0.01 ft/day, <br />a 1 ft drawdown is estimated to occur at a distance of 3,300 feet <br />from the mine perimeter, and the 5 ft. drawdown at distance 2,700 <br />feet from the mine perimeter. If the enveloping strata have <br />conductivity only 0.001 ft/day, the 1 ft drawdown occurs at 10,400 <br />feet. <br />The extent of drawdown should be nearer the low estimate based on <br />the observed very low distributed mine inflow rates and the locus <br />of inflows in fracture zones. Leakage will dampen uniform drawdown <br />within the mined seams, and fracture discontinuities will locally <br />overwhelm it. <br />Ground water in the William's Fork Alluvium will not be directly <br />affected by underground mining under this permit. Mine water <br />discharge to the William's Fork River is not anticipated to have a <br />measurable effect on water levels or water quality in the William's <br />Fork Alluvium. <br />16. The text on Page 2.05.14 states that "While it is considered <br />very unlikely that the Twentymile Sandstone will be significantly <br />affected, an estimate of worst case effects has been made." The <br />analysis provided assumed that longwall mining at the No.5 and No. <br />6 Mines induced a flow of 100 gpm from the Twentvmile Sandstone <br />even though the Twentymile Sandstone lies over 500 feet above the <br />seams to be mined. The resulting drawdown in the Twentymile <br />Sandstone at one mile from the mined area is estimated to be 60 <br />feet for the estimated hydraulic properties of the Twentymile <br />Sandstone. For mining activities to date, the inflows are <br />approximately 673 gpm but none of this inflow appears to be from <br />the Twentymile Sandstone, based on the fact that no drawdown has <br />occurred in the Twentymile Sandstone. <br />Based on the previous mining history, it is unlikely that future <br />mining in the E coal seam could induce a flow of 100 gpm from the <br />Twentymile Sandstone. Nevertheless, 100 gpm was used to indicate <br />the expected magnitude of drawdown if such impact occurred. Flows <br />of 100 gpm were determined to provide a reasonable worst case <br />impact because the maximum inflow measured historically along fault <br />zones in the mine have approached 100 gpm. <br />C. Bubaidence Control Plan <br />1. Map 31 has been revised to identify Well 259. <br />Enclosed are the following revision pages: <br />Index <br />pages xiiR, xiii, xivR, and xvRa <br />