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irrigation water use. <br />Potential Ground Water Use. This section will evaluate the use potential of the local, shallow <br />ground water aquifers by comparing the water quality against domestic drinking water standards, <br />livestock drinking water standards and irrigation use standards. The shallow aquifers will also be <br />evaluated in terms of water yield potential. <br />In comparison to domestic drinking water standards, all aquifers at the New Horizon 2 mining area <br />exceeded at least two of the drinking water standards and some exceeded as many as seven of <br />the standards (refer to Peabody Tables 7-32A and 7-32B). The most frequent domestic drinking <br />water standards exceeded were iron, manganese, ammonia and sulfate. Well GW-N16, an <br />underburden monitoring well in the New Horizon 2 mining area had the best overall water quality <br />and only exceeded the pH and ammonia standards. <br />The Dakota coal aquifers and the overburden aquifer in the New Horizon 2 mining area yielded <br />groundwater that exceeded one or more of the livestock drinking water standards. The coal aquifer <br />in the New Horizon 2 mining area has poor quality with regard to agricultural water use. <br />A comparison of TDS values for the New Horizon wells indicates that 3 wells exceeded the 5,000 <br />mg/1 limit, 12 wells yield water that could only be used for tolerant plants on permeable soils with <br />careful management practices, and 2 wells yielded water that might have adverse effects on crops <br />and requires careful management practices. Shallow ground water aquifers at New Horizon were <br />unsuitable for irrigation use. Plots of SAR's versus conductivity for each of the wells showed that <br />the groundwater fell into one of two categories. It was either a high to very high salinity hazard and <br />a low sodium hazard (12 wells) or a high to very high salinity hazard and a very high sodium hazard <br />(2 wells). <br />Wells yields and aquifer characteristics of the shallow aquifers at the New Horizon Mine were also <br />considered when evaluating potential water uses. Transmissivity values ranged from 77 to 1.1 <br />ft2/day and pumping rates above 1.5 gpm could not be maintained for any significant period of time. <br />Where short term, pumping withdrawal tests (McWhorter's analyses) were performed specific <br />capacities of only 0.1 to 0.6 gpm/ft could only be maintained over short time periods. Aquifer yields <br />were too low for irrigation purposes and only poor to fair for domestic purposes. Assuming yields <br />2.04.7-24