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• underburden well. The aquifer characteristics show spatial variability suggesting anisotropic <br />properties within the medium and probable boundary effects. <br />Ground Water Quality <br />The following section discusses the results of chemical analyses for ground water samples <br />collected within and adjacent to the New Horizon mining areas. The monitor well locations are <br />presented on Map 2.04.7-1. <br />In the following water quality discussions, aquifers in the New Horizon 2 mining area are discussed. <br />Because of the significance of the irrigation water on the local ground water hydrology, an attempt <br />is made to separate irrigation period effects from non-irrigation period effects. Additionally, any <br />seasonal variability irrespective of irrigation periods is addressed. Data presented for trace <br />elements is limited to the period from 1985 to the present, because of the questionable nature of <br />the chemicai data from earlier analyses. A further qualifier is that lead levels above the detection <br />limit, even after 1985 are ignored, because the only measurable values all occurred on the same <br />date in 1986 and measurable levels have not been detected since. Thus, the 1986 values are <br />• considered lab errors. The special chemical parameters (Be, Co, Li and V) required under ground <br />water agricultural standards from the Colorado Water Quality Control Commission were analyzed <br />in the New Horizon 2 mining area. <br />WeIIGW-N22monitoredthewaterqualityinthealluvialaquiferalongCalamityDraw. This well has <br />been replaced by wells GW-N39 and GW-N40. <br />The alluvial aquifer along Calamity Draw has a calcium magnesium sulfate water type both during <br />periods of irrigation and no irrigation. A slight lowering of TDS occurs during non-irrigation periods. <br />The mean TDS when irrigation is occurring is 3,349 mg/I and the mean TDS during periods of no <br />irrigation is 3,204 mg/I. Calcium and sodium concentrations increase slightly during periods of no <br />irrigation. The pH of the water at Well GW-N22 ranges from 7.2 to 7.7 with the mean value being <br />7.41. <br />A larger water quality data base is necessary to determine if there is any seasonal water quality <br />variability in the alluvial aquifer irrespective of the general irrigation effects. There is a suggestion <br />• Revised 18 Aug 2003 2.04.7-12 <br />