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West Elk Mine <br />2.04 -61 Rev. 06/05- PR10, 03/06- PR10, 04/06- PR10, 09/07- PR12; 05/22- MR462 <br /> <br /> <br />Rollins Sandstone <br /> <br />In the past, the Rollins Sandstone was thought to be a potential aquifer of regional importance, due <br />to its areal extent. However, more recent data and analyses indicate that the Rollins Sandstone is <br />not a regional aquifer (Mayo, 1998). Additional discussions are provided in Exhibits 17A, 18, and <br />18B. <br /> <br />MCC has constructed four monitoring wells completed in the Rollins Sandstone. These wells <br />included R-1, LP-1, SOM-128-H, and So.W-3 (See Map 34). No water was ever noted in LP-1 <br />primarily because the Rollins Sandstone is exposed to the atmosphere upgradient of this area. LP-1 <br />was removed from the monitoring program in June 1998 when the Lone Pine Gulch ventilation <br />portals were closed and reclaimed. SOM-128-H and So.W-3 were also removed from the <br />monitoring program in 1999. Monitoring well So.W-3 was rendered useless when B Seam mining <br />cut through the well. <br /> <br />Considerable hydrogeologic parameter estimations have been conducted on the Rollins Sandstone <br />in the vicinity of the mine, particularly in the areas associated with the BEM and 14HG Faults. As <br />shown in Table 5, a pumping test conducted on monitoring hole R-1 for just the Rollins Sandstone <br />portion of the well indicated that the formation was capable of producing only approximately 3 <br />gpm. Mayo and Associates (1998) reported both horizontal and vertical hydraulic conductivity <br />values for various intervals within the Rollins Sandstone. In general, horizontal hydraulic <br />conductivity values range from 1.0 x 10-4 to 1.2 x 10-2 ft/d while measured vertical values ranged <br />from 1.7 x 10-4 to 1.8 x 10-2 ft/d. <br /> <br />In addition, Mayo and Koontz (2000) reported horizontal hydraulic conductivity values for the <br />Rollins Sandstone from in-mine permeameter testing between 2.4 x 10-3 and 1.3 x 10-1 ft/d. These <br />data show that, with the exception of the fractured portion of the formation, the permeability of the <br />Rollins Sandstone is low. In fact, Mayo (1998) states that of the fifteen analyzed core samples <br />taken from the Rollins Sandstone between the BEM and 14HG Faults, only one “had sufficient <br />permeability to transmit water” and “the low permeability of all other samples make them effective <br />barrier to groundwater flow.” <br /> <br />This is further documented in CDRMS permit revision decision documents, where it was reported <br />that drill holes that penetrated the Rollins Sandstone near the Orchard Valley Mine (later called <br />Bowie No. 1 Mine) had an insufficient yield to sustain groundwater supply wells. <br /> <br />As discussed previously, groundwater monitoring wells completed in the Rollins Sandstone do not <br />provide reliable information on the groundwater systems within the unit (Mayo and Associates 1998 <br />and 1999). In addition, the groundwater systems are not areally extensive and not in hydrodynamic <br />communication with each other. For these reasons, MCC does not plan to continue monitoring or <br />complete any additional monitoring wells in the Rollins Sandstone, because it has concluded that <br />this formation does not produce sufficient quantities of groundwater for beneficial use. A review of <br />SEO permitted wells in the vicinity of the West Elk Mine confirms that there are no water wells <br />producing from the Rollins Sandstone.