Laserfiche WebLink
Quality of Surface Water <br />The primary impact of Yoast mining operations on surface water quality <br />will be an increase in total dissolved solids concentration resulting from <br />the occurrence of spoil springs after backfilled spoil in the mine pits has <br />become saturated. Using conservative assumptions regarding the amount <br />of inflows to the reclaimed pits, and the quality of spoil spring water, and <br />information gathered from the nearby Seneca II Mine in recent years, <br />Seneca Coal Company has estimated the changes in surface water quality <br />which may be caused by the Yoast Mine. The projected impacts on each <br />of the affected drainages near the permit area are summarized below. <br />Annand Draw <br />Following the occurrence of spoil springs at the Yoast Mine, the total <br />dissolved solid (TDS) content of surface water in Annand Draw is <br />projected to increase from 950 to 3938 mg/l. These values, and all TDS <br />values discussed below are mean TDS values during the irrigation season, <br />which 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. <br />Due to the minimal flows in Annand Draw, it is reasonable to assume that <br />no 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 />Grass,, 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 <br />Creek downstream from the mine. This conclusion is drawn by estimating <br />the quality of Grassy Creek water after salt loading from Yoast Mine spoil <br />springs, and comparing that projected water quality to current water <br />quality in Grassy Creek downstream from the Yoast permit area. Water in <br />lower Grassy Creek currently has an average TDS of 2584 mg/l, partially <br />due to the influence of spoil spring discharges from the Seneca II Mine. <br />Seneca Coal Company predicts that lower Grassy Creek TDS will be 2177 <br />mg/l after addition of Yoast spoil springs. Thus, Seneca Coal Company <br />concludes that TDS in Grassy Creek will not increase as a result of Yoast <br />Mine operations. <br />Using Seneca Coal Company's assumptions about spoil spring <br />development at the Yoast mine, and the existing baseline water quality <br />data for lower Grassy Creek, the Division estimated the TDS of lower <br />Grassy Creek after establishment of Yoast spoil springs will increase by <br />approximately five percent. Because the quantity and quality of Grassy <br />Yoast Mine 28 December 15, 2010