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RULE 2 PERMITS <br /> Summary of Groundwater Conditions <br /> The coal beds of the Williams Fork Formation that are to be mined are at a high elevation and are <br /> truncated by the mining operation to the north, Goodspring Creek to the east and Taylor Creek to <br /> the west. As a result, the coals and upper sandstones are drained. Perched aquifers exist in the <br /> coals and sandstones, but exhibit little lateral or vertical continuity. Cascading waters from <br /> perched zones were encountered during drilling of exploration holes on the lease. No substantial <br /> quantities of water were encountered through the mine section or in the sandstones below the coals <br /> that are to be mined. <br /> The Trout Creek Sandstone of the Iles Formation is the first major, regional aquifer that can be <br /> recognized on the mine property. The sandstone occurs approximately 800 feet beneath the lowest <br /> coals to be surface mined. <br /> The geologic characteristics of the Williams Fork and Iles Formations appear to demonstrate <br /> natural low porosity and permeability that is enhanced locally by fracturing. Since most of the beds <br /> in the Williams Fork are not laterally extensive, and due to the relatively low yielding <br /> characteristics, the Williams Fork in this area can not be considered to be a significant aquifer. <br /> The groundwater quality has been shown to be of poor quality and is variable from site to site. A <br /> study conducted in 1974 and 1975 revealed that the specific conductance of the groundwater <br /> averaged 1390 mmhos and ranged 720 to 2700 mmhos. The results of a 1979 study conducted by <br /> Leonard Rice Consulting Water Engineers show that overall quality has not been significantly <br /> affected by mining activities. <br /> The report stated that measurements made in 1979 were within the range of variation seen in 1974 <br /> and 1975, though they were in general lower than the historical data. The most probable <br /> explanation of this apparent increase in water quality may be a dilution effect from the relatively <br /> high runoff throughout the spring and summer of 1979. The report stated that there is no evidence <br /> of contamination of the groundwater by the surface mining of Colowyo Coal Company.Additional <br /> monitoring of the Goodspring Creek alluvium/colluvium and downdip of the Gossard Loadout <br /> also indicates groundwater quality has not been significantly affected by mining activities. <br /> Surface Water <br /> Occurrence of Surface Water <br /> General Area <br /> The surface water of the general area is characteristic of a high altitude environment. The climate <br /> is semi-arid, characterized by low precipitation, large daily temperature changes, low humidity, <br /> moderate winds and abundant sunshine. Precipitation averages 21.5 inches across the drainages in <br /> the "general area"per year resulting in erratic and low flows in the major drainages near the mine <br /> area. Climatic data is discussed in detail in Section 2.04.8. Surface flows are dominated by the <br /> occurrence of runoff events resulting from either snowfall or rainfall. Snowfall derived runoff <br /> dominates the hydiulugic cycle, supplemented by periodic intense thunderstorms which result in <br /> Rule 2 Permits 2.04-20 Revision Date: 12/20/19 <br /> Revision No.: TR-135 <br />