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The Wolf Creek coal is split into an upper and lower unit. The lower seam is about 16 feet thick, while the upper is about 7.5 feet thick. Above the Wolf Creek seam within portions of the permit area, and separated by 100 [0 150 feet of interburden is the Sage Creek seam. The Sage Creek seam ranges from 2 to 5 feet thick where it occurs in the permit area. SCC initiated mining of selected areas of both the Wolf Creek seam and the Sage Creek Seam in the South Extension Area, upon approval of PR-3, in 2003. Neither seam was previously mined at Seneca IIW. Overlying the Sage Creek seam is a 50 to 65 foot thick zone of sandstone interbedded with shales and siltstones. Itrunediately above this sequence is the Wadge coal seam. The Wadge coal seam is the most continuous in the area and is the only seam that was extracted prior to 2003. The outcrop strikes about north-south, and dips 8 to 14 degrees. The Wadge is also split into upper and lower seams. The lower is two to three feet thick, and is separated from the 10 foot thick upper seam by two to five feet of shales and sandstones. Overlying the Wadge is about 560 feet of sandstones, shales, and coal, including the Lennox Coal Seam, which has been eroded away in places. Overlying this lower unit of the Williams Fork Formation is the 130 feet thick Twenty Mile Sandstone. The upper most unit of the Williams Fork Formation consists of interbedded sandstones, shales, and thin coals. The su~cial geology of the area is composed chiefly of sedimentary rocks, of marine and non-marine origin. These sedimentary rocks were formed through the transgression and regression of an epicontinental sea. Alluvial deposits are locally present in stream valleys, particularly along the larger streams. Colluvial slides and slumps are also present in canyons and gullies throughout the area. Slide bodies which could potentially affect the stability of mining related structures in the northern portion of the permit area have been identified, and mitigation measures are addressed in Section VII., "Bacl~illing and Grading" of this document. Geologic baseline information including: local and regional structure; stratigraphy; and information on interburden, overburden and coal geochemistry is provided in Volume 2, Tab 6, of the permit application. Ground Water Bedrock ground water aquifers have been identified as the Wolf Creek coal seam, the Wadge coal seam, the Wadge overburden including the discontinuous Lennox coal seam and the Trout Creek sandstone. Recharge to these and other aquifers in the area is a function of infiltration of snow melt and rainfall at outcrops along the anticline. All aquifers exhibit water table conditions near the outcrop. However, observation wells installed downdip indicate the aquifers are all under artesian conditions with increased pressure related to increased depth. Quality in all aquifers is poor and undesirable for use as either a drinking or irrigation supply. The Seneca II-W Mine permit area lies on the western flank of the Sage Creek Anticline, a local structure located within the more regional Sand Wash Basin. The Sage Creek Anticline is Seneca II-W Findings Document 9 November 17, 2004 Permit Revision No. 4