2010-04-16_PERMIT FILE - C1996083A (11)

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2.04.7 Hydrology Description Upper Perched Water Zone). The "D" coal seam is located 400 feet above the Rollins Sandstone and is separated from the Rollins Sandstone by sandstones, siltstones, clays, and coal seams. Although no data for permeability or transmissivity of the saturated portions of the coal bearing member of the Mesaverde Formation are available within the permit area, the experience by others (Brooks,1983) suggests that the Mesaverde Formation transmits little water. Mountain Coal Company reports a yield of 3 gpm from the 245 interval of the Rollins Sandstone from its monitoring well R-1 (MCC permit section 2.04.7). The primary (granular) permeability is low due to the lithologic composition of the sandstone and the secondary (fracture) permeability is not well developed. Extensive core drilling within this strata shows that fracture zones are not well developed. Similar observations were made in the Orchard Valley underground mine by CWI. Fracture zones or zones of lost circulation during drilling do not appear to extend from hole to hole. Fracture and fault zones, although encountered, are not well developed. The groundwater flow direction in the sandstone strata in the coal bearing member of the Mesaverde Formation is from the recharge area near the outcrop of these strata north toward the lower parts of the basin. An interpretation of the potentiometric surface in this water bearing strata is shown on Maps 10 and 11. These were prepared utilizing exploration data obtained from static water measurements from monitoring wells and, geophysical logging and drill logs. A • table entitled "Static Water Levels in Exploration Drill Holes" located in Volume III, Exhibit 3, was compiled primarily from geophysical logs run during the exploration process. In some older drill holes on the site, few field records of the type and amount of drilling fluid, casing (if any), and logging activities are available. Although, the drill medium is usually noted on the electric logs (if available). More documentation exists for the more recently drilled holes. Many of the deeper holes were drilled with mud, such that the static water level recorded should be considered dubious at best. Any holes drilled with bentonite based mud can greatly inhibit the hydrologic properties due to mud cake within the drill hole. When air and foam are used as a drilling medium, the hydrologic conditions of the in-situ rock are virtually unaffected, and observation of subtle inflow or lost circulation zones are greatly enhanced. The progress of these holes was monitored in the field and recorded by competent personnel. Drill holes 13, 15, 16, 25, 34B, 38, 39, 42, 49, 52, 54, 55, 57, 57a, 58, 58a, 65, 66, DH-67B, DH-67D, DH-67Abv, DH-67BIw, DD-NM4X98-27, DD-NM4X98-28, DD-NM4X98-29, TC-03-01(B), TC-03-01(R), TC-03-02, TC-03-03 were completed as monitoring wells in the bedrock following exploration. Refer to section 2.05.6 for further discussion of the deep bedrock groundwater monitoring program. n -__rl PR-10 2.04 - 27 - 09/26/08 A PPrzou~ ,l j~w~~