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<br />C. Additional Comments on Probable Hydrologic Consequences <br />1. There is some concern within the Division as to the potential <br />impacts of the Mine No. 3 and Middle Creek Detention Basins on the water <br />quality of the alluvial aquifer syttem within the permit and adjacent <br />areas, Both detention basins are located adjacent to alluvial deposits <br />and are projected by the applicant to be in hydrologic communication with <br />the alluvial ground water system. Therefore, the "Probable Hydrologic <br />Consequences" section of the permit application should be expanded to <br />include a discussion of potential water quality effects of the detention <br />basins on the alluvial ground water system. The discussion should <br />include detailed geologic cross sections extending at least 500 feet <br />adjacent to the basins, clearly identifying the relationship between the <br />basins and adjacent undisturbed bedrock, backfilled overburden material, <br />and alluvial deposits. Additionally, the discussion should include an <br />estimation of contribution from water percolating through reclaimed <br />spoils into the basins, an estimation of seepage rates out of the basins, <br />and a predicted "worst case" value of total dissolved solids of water <br />contained within the detention basins. <br />RHSPONSH: <br />The Mine No. 3 and Middle Creek Mine Detention Basins are <br />located in mine pits which did not eatend into the alluvial aquifer <br />of Middle Creels at any location. In fact, the mine pits and the <br />detention basins are separated from the alluvium of Middle Creek by <br />bedrock shale layers which preclude hydrologic communication. A <br />dissuasion of the ground water aspects of the detention basins is <br />presented on revised page 2.05-168a. Cross-sections showing the <br />-18- <br />