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upper seam by two to five feet of shales and sandstones. Overlying the Wadge is about 560 feet <br />of sandstones, shales, and coal, including the Lennox Coal Seam, which has been eroded away in <br />places. Overlying this lower unit of the Williams Fork Formation is the 130 feet thick Twenty <br />Mile Sandstone. The upper most unit of the Williams Fork Formation consists of interbedded <br />sandstones, shales, and thin coals. <br />The surficial geology of the area is composed chiefly of sedimentary rocks, of marine and <br />non - marine origin. These sedimentary rocks were formed through the transgression and <br />regression of an epicontinental sea. <br />Alluvial deposits are locally present in stream valleys, particularly along the larger streams. <br />Colluvial slides and slumps are also present in canyons and gullies throughout the area. Slide <br />bodies which could potentially affect the stability of mining related structures in the northern <br />portion of the permit area have been identified, and mitigation measures are addressed in Section <br />VII., "Backfilling and Grading" of this document. <br />Geologic baseline information including: local and regional structure; stratigraphy; and <br />information on interburden, overburden and coal geochemistry is provided in Volume 2, Tab 6, of <br />the permit application. <br />Grnnnd Water <br />Bedrock ground water aquifers have been identified as the Wolf Creek coal seam, the Wadge coal <br />seam, the Wadge overburden including the discontinuous Lennox coal seam and the Trout Creek <br />sandstone. Recharge to these and other aquifers in the area is a function of infiltration of snow <br />melt and rainfall at outcrops along the anticline. All aquifers exhibit water table conditions near <br />the outcrop. However, observation wells installed downdip indicate the aquifers are all under <br />artesian conditions with increased pressure related to increased depth. Quality in all aquifers is <br />poor and undesirable for use as either a drinking or irrigation supply. <br />The Seneca II -W Mine permit area lies on the western flank of the Sage Creek Anticline, a local <br />structure located within the more regional Sand Wash Basin. The Sage Creek Anticline is thought <br />to control local ground water flow, as artesian head increases with distance from the anticlinal <br />axis. <br />Ground water occurs in the alluvium associated with Hubberson Gulch within and adjacent to the <br />permit boundary. Quality of this water prohibits its use for drinking and severely limits its use for <br />irrigation. Baseline data indicate that drinking water and irrigation standards were exceeded for <br />TDS, Conductivity and Manganese. <br />Surface Water <br />The mine permit boundary encompasses two surface watersheds. Most of the mine site and the <br />major portion of the disturbed area are in the Dry Creek watershed, and will drain into Hubberson <br />Seneca II -W Findings Document 8 C- 1982 -057 <br />Permit Revision No. 6 January 6, 2012 <br />