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is located in the immediate proximity of Pond 002, suggests that a portion of the pond bottom <br />may intersect or immediately overly the top of the Lewis shale. Hydraulic communication or <br />direct contact with the Lewis shale would cause water quality degradation and increased salt <br />concentrations. <br />Discharges from sediment ponds 001 and 002 should not significantly affect the chemistry of <br />Dry Creek below the loadout because coal paste conductivities, which are worst case <br />indications of runoff water quality, are 2 to 7 times lower than the receiving stream (Dry <br />Creek) conductivities. The potential for pond discharges are generally quite small. Pond 002 <br />discharged during spring runoff in 1996, the first observed discharge since 1987 and Pond <br />001 typically only discharges in the spring when receiving streamflows would be <br />considerably greater and would readily dilute the pond discharge. In conclusion, the loadout <br />will not measurably impact the water quality of Dry Creek or any potential water use. <br />In addition, CDMG requested HGT run coal leachate analyses to further evaluate potential <br />impact to Dry Creek and alluvial water quality. The column leach tests were performed by <br />ACZ Laboratories, Inc. on samples of new and old coal using extraction Method 1312. Four <br />leachate tests were performed, one with new coal, two with old coal, and one without coal to <br />verify control levels. Twenty -five chemical parameters were analyzed for, including those <br />with standards for the reach of the Yampa River Dry Creek is tributary to. The results of the <br />four column leachate tests are presented in Attachment 15 -2. Both the new and old coal <br />leachate parameter concentrations appear to be quite favorable. Only one parameter, boron <br />for the new coal, exceeds the Yampa River standard of 750 ug/l. For the parameters TDS <br />and SO4, both the receiving stream and alluvial background levels are significantly higher (6 <br />to 53 times higher). Boron levels in the alluvium, including that portion represented by the <br />new alluvial well, are comparable to or exceed the leachate boron levels. Table 15 -1 presents <br />the coal leachate water quality comparison against the Yampa River stream standards. <br />To evaluate coal stockpile leachate impacts on the Dry Creek water quality, ten -year, seven - <br />day high and low flows were determined and mixed with calculated leachate volumes. The <br />ten -year high flow for Dry Creek was determined using a regression equation development <br />by the USGS in Water - Resources Investigation Report 85 -4086 for northwest Colorado <br />drainages (Kircher et.al., 1985). The regression equation is: <br />TR -10 3 Revised 02/13 <br />