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The potential effects on the water quality will be estimated on the basis of controlling <br />chemical reactions, by analyzing the spoils-water chemistry at Nucla, and by application <br />of a methodology developed by Hounslow, et al. (1978, pp. 177-180). <br />The applications of the geochemical speciation code PHREEQE to the study of water <br />chemistry at Nucla and Nucla East has been previously discussed. The study resulted in <br />several pertinent conclusions. <br />1. The major ion chemistry is controlled by the solubilities of gypsum and calcite. <br />2. Concentrations of cadmium and lead appear to be controlled by the solubilities of <br />otavite and cerrusite, respectively. Local exceedences of the Drinking Water <br />Standard for cadmium have been noted. The standard may naturally be exceeded for <br />lead as well, but the laboratory analyses are in doubt. <br />3. No miner alogic controls were apparent for boron or nitrate, or for constituents whose <br />concentrations were less than their detection limits. <br />• 4. Even though the chemistry of the water is largely controlled by equilibrium with a <br />few minerals, there is variability in water chemistry, probably because of <br />differences in a water's history and degree of mixing with other water. <br />5. Acidic problems should be naturally ameliorated by mixing of acidic water with the <br />more prevalent Ca-Mg-504 water, and by reaction with calcite. <br />The concentrations of elements or ions that are controlled by mineral solubilities are not <br />expected to change greatly because of mining. The geochemical analysis which was <br />performed provides no definitive information on species which are likely to be affected by <br />sorption or ion exchange, such as boron. <br />Hounslon et al. (1978) developed a technique for predicting whether mining would likely <br />cause changes in water quality, based on hydrologic settings, existing water quality, and <br />core properties. Following this methodology (coal below or in aquifer, TDS greater than <br />1,000 mg/1, and the widespread occurrence of Ca-Mg-504), mining is not likely to cause a <br />• change in the chemistry of the water. <br />17-58 Revised 04/11/88 <br />