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Accurate prediction of water quality of discharges from the flooded <br />workings was an issue discussed at length during the permitting process. <br />The applicant was not aware of any analyses performed on discharges from <br />flooded workings in western coal mines. They ultimately agreed that the <br />quality of the calcium/magnesium sulfate water from the backfilled spoils <br />was a worst case approximation of flooded workings discharge. The 100' <br />of rubblized rock overlying the workings which will remain following <br />retreat mining is roughly equivalent to the overburden backfill at a <br />surface mine. However, the residence time and consequent chemical <br />reduction within the flooded workings differs from that observed in the <br />Eckman Park spoils where the oxidation potential (Eh) was measured at <br />between +221 and +304 mv, at pHs of 6.7 and 6.6 respectively. These <br />values are representative of transitional environment between oxidized <br />and reduced solutions. <br />It is anticipated that metals and sulfides will be more soluble and <br />consequently present in higher concentrations than currently observed in <br />spoils discharge waters. Water from flooded workings will predominantly <br />influence waters in Fish Creek. Dilution from Fish Creek is projected to <br />minimize the influence of these waters as discharges during low flow will <br />only increase total water quantity 6.6-15% (TABLE 13). <br />No acid forming, toxic-forming or alkalinity producing materials have <br />been identified through geochemical sampling. The permit revision <br />application is in compliance with Rules 2.04.5 and 2.04.6. <br />VI. Hydrologic Balance - Rules 2.04.5, 2.04.7, 2.05.3(4), 2.05.6(3) and <br />4.05 <br />A, Ground Water Information <br />The ground water information within the permit revision application is <br />found in section 2,04.7, of Volume 1, Exhibits 9, 13, 14, 27, 33, 35, 37, <br />38 and 39, Figures 1, 2, 3, 4 and 10, Tables 7, 8, 9, 11, 60, 61, 62 and <br />67, Maps 4, 12, 13, 14, 33, 35 and 36: <br />A description of ground water occurrence, ground water monitoring and <br />mining impacts on ground water within the permit and adjacent areas can <br />be found in Section IX, "Probable Hydrologic Consequences of Mining and <br />Cumulative Hydrologic Impact Study" of this document. <br />Discussions about the mine's hydrologic impacts to the ground water <br />regime centered on the applicant's evaluation of the existing piezometric <br />surface and TCC's predictions of lateral and vertical drawdowns from <br />dewatering. CMLRD also requested clarification of the relationship <br />between alluvial aquifers and their adjoining streams. Lastly, the <br />applicant was requested to evaluate the influence of adjacent backfilled <br />spoil aquifers on their operation and to make predictions about the <br />influence of spoils aquifers on water quality in the drainage. <br />-13- <br />