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<br />r • • <br />-2- <br />IV. Geology (2.04.5, 2.04.6) <br />The results of roof and floor analyses are still to be submitted to the <br />Division. The samples are presently at the laboritory (see page 8 of <br />Response). The core log showing the detailed lithology of sampled <br />interval in core hole CH-82-68 and CH-82-64 are not included in Exhibit <br />14a. The applicant should submit these core logs. <br />The original permit revision application does not contain complete <br />chemical analyses of the Wadge coal seam. Table 1, "Wadge Coal Seam <br />Analysis" contain only an analysis of moisture, ash, heat value, total <br />sulfur, sulfate sulfur and pyritic sulfur. A chemical analysis of coal <br />for an underground mine which will be flooded should also include an <br />analysis of soluble salts and toxic elements contained in the coal. <br />These analyses are important in evaluating the impacts of the exposed <br />coal seam on the mine water quality both during and after mining. <br />VII. Protection of the Hydrologic Balance (2.05.6(3)) <br />Map l0a does not contain contours of equal water level decline <br />surrounding the underground mine. However, the applicant should develop <br />and run a more sophisticated model of mine inflows and ground water level <br />declines and then construct a series of potentiometric maps for periods <br />during and after mining. This model should consider factors such as <br />verticle leakage, discharge/recharge boundary (Fish Creek), recharge <br />boundaries (Foidel Creek and outcrop areas), transition from artesian to <br />water table conditions during drawdown (storativity to specific yield), <br />dips of the aquifers (varying hydrologic head with depth), caving height <br />over entries and panels, etc. <br />This analysis may be best handled using a well field model with <br />production well along mine entries and panel areas, and immage well <br />projected across boundaries. Production wells and immage wells could be <br />added with time to the model to simulate expansion of the mine workings. <br />~~"~_ This model may also serve in simulating post-mining rebound of ground <br />'~.,~ water levels. By converting the production wells to observation wells, <br />'e~, ti the applicant could calculate the time required to re-establish a <br />-a n'`' hydrolic head sufficient to drive a pollutant plume and also to <br />fcciy, re-establish equilibrium water levels. <br />A similar modeling of ground water at the Middle Creek Underground Mine <br />may be required prior to permitting this mine, and also to evaluate the <br />impacts of all anticipated mining in the general area of the Foidel Creek <br />Mine. <br />The applicant should provide to the Division copies of the mine water <br />~~~ quality analyses which were used in calculating the impacts of the Foidel <br />Creek Mine. The 800 mg/1 value for T.D.S. which was used in these <br />calculations is considerably lower than T.D.S. values in mine discharges <br />from other coal mines on the western slope. Also, stagnation of water <br />within the mine upon its closure may produce levels of T.D.S. as much as <br />10 time higher than in an active mine. <br />