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Armand Draw <br /> Following the occurrence of spoil springs at the Yeast Mine, the total <br /> dissolved solid (TDS) content of surface water in Armand Draw is projected <br /> to increase from 950 to 3938 mg/l. These values, and all TDS values <br /> discussed below are mean TDS values during the irrigation season, which <br /> was considered to last from June 1 through September 30. <br /> No use is presently made of this water before it flows into Grassy Creek. Due <br /> to the minimal flows in Armand Draw, it is reasonable to assume that no <br /> future use of this water will be made, other than livestock watering. <br /> Therefore, this increase in salinity will not result in material damage. <br /> Grassy Creek <br /> An evaluation of the water quality impacts of the Yoast Mine on Grassy <br /> Creek in the permit application projects no increase in TDS in Grassy Creek <br /> downstream from the mine. This conclusion is drawn by estimating the <br /> quality of Grassy Creek water after salt loading from Yeast Mine spoil <br /> springs, and comparing that projected water quality to current water quality <br /> in Grassy Creek downstream from the Yoast permit area. Water in lower <br /> Grassy Creek currently has an average TDS of 2584 mg/l, partially due to the <br /> influence of spoil spring discharges from the Seneca II Mine. Seneca Coal <br /> Company predicts that lower Grassy Creek TDS will be 2177 mg/I after <br /> addition of Yoast spoil springs. Thus, Seneca Coal Company concludes that <br /> TDS in Grassy Creek will not increase as a result of Yeast Mine operations. <br /> Using Seneca Coal Company's assumptions about spoil spring development <br /> at the Yeast mine, and the existing baseline water quality data for lower <br /> Grassy Creek, the Division estimated the TDS of lower Grassy Creek after <br /> establishment of Yoast spoil springs will increase by approximately five <br /> percent. Because the quantity and quality of Grassy Creek water is marginal <br /> or unsuitable for use as domestic or irrigation water, this projected increase <br /> in salinity will not affect any uses of Grassy Creek water. The only current <br /> use of Grassy Creek water (livestock watering) will not be impaired by the <br /> projected increase in salinity. <br /> Sage Creek <br /> Life-of-mine plans for the Yoast Mine anticipate coal extraction within the <br /> Sage Creek watershed during the second and third permit terms. Preliminary <br /> estimates by Seneca Coal Company indicate that TDS concentrations in Sage <br /> Creek downstream from Yoast spoil springs may increase from 641 to 2118 <br /> mg/l. <br /> YOasl Mine 28 Oclobar 19, 1999 <br />