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prevent ash leachate migration from the walls and floor of the pit (Figure 1). Another measure of <br />protection is provided by the requirement to place ash at least 5 ft. above the postmining water <br />table of local aquifers. Placement above the water table was done to prevent saturation of the ash <br />by native ground water. The relatively flat topography of the reclaimed pit areas would preclude <br />significant formation of surface spoil springs or seeps at the Keenesburg Mine. <br />Compliance with the Interim Narrative Standard for Ground Water, Section 41.5(C)(6)(a)(i) <br />of Colorado Water Quality Control Commission's Basic Standards for Ground Water. <br />Compliance with Section B of the Interim Narrative Standard would indicate compliance with <br />the Basic Standards. The water quality standard applicable under Section B is "background TDS <br />times 1.25". (TDS refers to total dissolved solids.) Considering Ennis Draw alluvial ground <br />water as "Potentially Useable Quality" and premining quality as the "background level" (see <br />definition of background level in Regulation 41.3.1 of the Basic Standards), Table 1 below <br />shows that the TDS concentration in ground water in well DH-96 is no more than its background <br />(premining) TDS value multiplied by 1.25; therefore, the mine in is in compliance with the Basic <br />Standards for Ground Water. <br />Table 1 - Premining/postmining comparison of total dissolved solids in Ennis Draw <br />Alluvial monitoring well DH-96 <br />TDS concentration <br />(0.7 X specific conductivity) <br />Background value <br />times 1.25 Postmining <br />ears: 1982-1984 (Years: 1999 -2003) <br />1750 mg/1 1399 mg/I <br />Compliance with requirement to minimize ground water hydrologic impacts inside the permit <br />area /CDMG regulation 4.053(2)]. The approved post-mining land use in the permit area is <br />rangeland. As previously discussed, ground water in bedrock and alluvial aquifers have not been <br />adversely impacted by mining and reclamation operations at the Keenesburg Mine. The <br />approved post-mining land use has not been impaired by the changes to the ground water <br />hydrologic balance caused by mining operations. The changes were the minimum that can be <br />expected from a surface coal mining operation. <br />7