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<br />It is expected, based upon the applicant's measurements in Little Grassy <br />Creek, a stream draining their Seneca II Mine, that TDS levels may double in <br />Hubberson Gulch during mining and reclamation. The waters of Hubberson Gulch <br />are not actively utilized for irrigation due to elevated salinities. The <br />water will be usable for livestock watering and by wildlife. <br />Flow from several springs discharging to the surface water system will be <br />interrupted by mining activities. These springs help to classify Dry Creek as <br />an intermittent stream. It is believed that the post-mining back filled pit <br />water will discharge to the surface water system. This discharge will be <br />greater than the current combined spring discharge. <br />The major impact of mining will be the development and subsequent discharge to <br />the surface system of spoils aquifer waters. As each successive pit is <br />reclaimed, a spoils aquifer will begin to develop. The water necessary to <br />recharge this aquifer will be derived from precipitation, overland flow, and <br />discharge from the Williams Fork formation overburden and the Wadge coal. <br />The backfilled pits in and of themselves will display unconfined conditions, <br />however the pits will be surrounded on the sides and be underlain by <br />relatively confining units. The underlying material will be even more <br />confining than the sides. <br />As water enters the reclaimed areas it will tend to migrate through the spoils <br />toward the lowest point in the pit. While some of this water may be lost to <br />the walls, the major portion of it will stay in the pit, as the permeability <br />of this material is greater than that of either the walls or the floor. It is <br />projected that the water quality of spoils at the Seneca II-W Mine site will <br />approximate that at the nearby Seneca II Mine. The Seneca II Mine spoils <br />aquifers are typically high in, or exhibit elevated levels of, total dissolved <br />solids, magnesium, manganese, molybdenum, and sulfate. <br />Complete water quality analyses of two spoils aquifer wells are published in <br />the Seneca II Mine 1984 Annual Hydrology Report, Appendix B. <br />As the aquifer is developing, the water will be of slightly poorer quality <br />than the above assumptions, but as the more easily leached constituents are <br />lost, the quality should approximate that at Seneca II Mine. <br />Analysis of spoils water from the Seneca II Mine indicates that this <br />magnesium-calcium sulfate water has elevated levels of sulfate and magnesium. <br />TDS values vary between 2,200 and 4,000 mg/1. <br />Eventually, water at Seneca II-W Mine will begin to discharge to the surface <br />as the water elevation exceeds the ground level or when sufficient head is <br />developed. This discharge may be contained in a sediment pond, or may flow <br />into Hubberson Gulch along the access road. <br />If the spoils discharge is intercepted by a sediment pond, it will either be <br />lost to evaporation, or may infiltrate into the underlying Williams Fork <br />formation. Infiltration of this water should pose no hydrologic threat to the <br />Williams Fork system on a local or regional scale. <br />-36- <br />