2013-10-02_PERMIT FILE - C1981019A (3)

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RULE 2 PERMITS A search of the Colorado Office of the State Engineer's files revealed 71 permitted wells located within the proposed permit revision area and extending at least one mile beyond the perimeter of the expansion area. Of these, five permitted wells have reported well yields of 20 gallons per minute (gpm) or greater. The maximum reported yield of these wells is 50 gpm. The remaining wells have reported yields of less than 16 gpm; with most of the wells having reported yields of less then 5 gpm. There are 49 wells with reported flows of 0 gpm. Most of the permitted wells are used for monitoring purposes, however, a few of the permitted wells support domestic and livestock uses. The permitted wells are illustrated on Map 11 A. Detailed Groundwater Information Groundwater Characterisfics -The principle structural features in the permit revision area that influence groundwater flow are an unnamed syncline, located southeast of the South Taylor mining area, and an unnamed anticline, located beneath the southern part of the South Taylor/Lower Wilson permit revision azea. The synclinal axis generally corresponds to the drainage valleys of the West Fork of Good Spring Creek. The unnamed anticline parallels the topographic divide between Wilson and Good Spring Creek. The result is a stratigraphic dip-slope towards Good Spring Creek. Both the anticline and syncline axes plunge in a northeasterly direction. These structural features result in the area at the top of the anticline being the recharge area for groundwater, and the area near Good Spring Creek being the discharge area. The area for recharge of groundwater is limited to the eastern half of the anticline and does not result in the formation of a continuous aquifer in the South Taylor/I,ower Wilson permit revision area. Groundwater in the South Taylor/Lower Wilson permit revision area occurs under perched conditions in areas that are not laterally extensive, and in the alluvial of the stream valleys. The perched azeas aze generally within the interbedded and lenticular sandstones and on the contacts between different lithologic units of the Williams Fork Formation. Beneath the South Taylor mining area, the top of the Trout Creek Sandstone underlies the lowest seam to be mined by approximately 590 feet. The coal seams to be mined in the South Taylor and Lower Wilson proposed mining azeas aze lower in the coal seam sequence than found at the Colowyo Mine. For South Taylor, the lowest seam currently considered to be mined is the G8~ seam. At Lower Wilson, the I seam is the main seam to be underground mined. The South Taylor and Lower Wilson mining areas have similar lithology to that found in the current Colowyo mine. However, the proposed mining areas are located topographically and structurally higher than what is encountered at the Colowyo mine.. Therefore, the elevations of the base of the coal seam floor to be mined in both of these areas are generally higher than the old surface elevation of the already mined East and West Pits. The topographic high and geologic structure in the South Taylor mining area (an anticline) provides little. recharge area for the underlying beds and seams. The Trout Creek sandstone, a major regional aquifer, and the overlying coal sequence, outcrop west and southwest of these areas and thus are above any sources for continuous water recharge. Thus, there is no source to contribute to artesian conditions in the proposed coal seams to be mined. Monitoring well MWST-06-04 has water at an elevation of 7,915 feet (below the floor of the G9 seam), and piezometer PST-06-17 did not encounter water at or above the G8/9 seam. These boreholes aze shown on Map 10A. South Taytor/Lower Wilson -Rule 2, Page 39 Revision Date: 11/30/06 Revision No.: PR-02