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' Section 816.51(a) Continued. <br />bench foundation. After reclamation there will be adequate ground <br />water for plant growth during revegetation and for support of the <br />postmining land use (rangeland). <br />(b) Minimizes disturbances to the prevailing hydrologic balance in the <br />mine plan area and in adjacent areas; and <br />•r <br />As discussed in detail in Section 179.15, the Coalmont Formation, <br />which contains the Sudduth Coal Seam, is a low-yield source of ground <br />water, generally less than 10 gpm (Voegeli, 1965). The Sudduth Coal <br />Seam is an aquifer of relatively low permeability and specific yield, <br />as demonstrated by pump tests of monitor wells in the Mine Plan Area. - <br />No private wells or springs are known to produce water from the coal <br />aquifer in the Mine Plan Area or adjacent areas. Any small amount of <br />water contained in the isolated perched gravel pockets in the Mine <br />Plan Area is intermittent. Therefore, ground water resources are of <br />little importance to the prevailing hydrologic balance in the Mine <br />Plan Area. <br />Following mining and reclamation, the storage capacity of the <br />unconsolidated backfill in the mine pits will be higher than that of <br />the premising condition, but storage characteristics in the <br />undisturbed portion of the coal aquifer will beyunaffected by mining. <br />This is because the coal is already saturated down-gradient from the <br />area to be mined, and piezometric pressure on the aquifer will not be <br />changed measurably after mining is completed. The undisturbed coal <br />aquifer is confined by shale aquitards above and below the Sudduth <br />Coal Seam;_t6arefore, th~slighY..modif_ication. tn~echarge capaci-ty..:--- .._ <br />will have a minimal effect on the hydrologic balance in the Mine Plan _.- ..-- <br />Area. <br />816-73R <br />Revised - J <br />1991 <br />