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2.04.7 Hydrology Description <br />coal seams. A potentiometric surface map of the D -Seam is presented on <br />Map 10B. <br />Maps 10 and 11 were prepared utilizing exploration data obtained from static <br />water measurements from monitoring wells and, geophysical logging and drill <br />logs. A table entitled "Static Water Levels in Exploration Drill Holes" located <br />in Volume III, Exhibit 3, was compiled primarily from geophysical logs run <br />during the exploration process. <br />In some older drill holes on the site, few field records of the type and amount <br />of drilling fluid, casing (if any), and logging activities are available. Although, <br />the drill medium is usually noted on the electric logs (if available). More <br />documentation exists for the more recently drilled holes. Many of the deeper <br />holes were drilled with mud, such that the static water level recorded should <br />be considered dubious at best. Any holes drilled with bentonite based mud <br />can greatly inhibit the hydrologic properties due to mud cake within the drill <br />hole. When air and foam are used as a drilling medium, the hydrologic <br />conditions of the in -situ rock are virtually unaffected, and observation of <br />subtle inflow or lost circulation zones are greatly enhanced. The progress of <br />these holes was monitored in the field and recorded by competent personnel. <br />West of Terror Creek the geohydrologic setting changes. The "D" coal seam <br />is not identifiable and faults are present that complicate groundwater level <br />projections west of Terror Creek. West of Terror Creek the water bearing <br />zones of concern are the zones in the B -Seam and above the B -Seam. Map <br />10A depicts the potentiometric surface above the B -Seam and Map 10B <br />depicts the potentiometric surface in the B -Seam. Map 10A, potentiometric <br />surface above the B -Seam is a more regional projection than Map 10. Map <br />10 uses specific wells in order to project groundwater contours above the D- <br />Seam. The potentiometric surface shown on Map 10A utilizes groundwater <br />elevations, regional dip and faults in order to project groundwater elevations <br />east and west of Terror Creek. <br />Although no data for permeability or transmissivity of the saturated portions <br />of the coal bearing member of the Mesaverde Formation are available within <br />the permit area, the experience by others (Brooks, 1983) suggests that the <br />Mesaverde Formation transmits little water. Mountain Coal Company reports <br />a yield of 3 gpm from the 245 interval of the Rollins Sandstone from its <br />PR -14 2.04-39- 03/14 <br />