Laserfiche WebLink
West Elk Mille <br />In addition to water level data collection, hydrogeologic characteristics (i.e. transmissivity, <br />hydraulic conductivity, and yield) of many of these formations have been obtained from pumping <br />and slug test analysis. Transmissivity values from pumping tests were estimated from Lohman <br />(1975), using the following equation: <br />Q _ 4 7C T <br />S 2.301oor C2.25Tt <br />:-n 10 <br />71 S <br />Where: <br />Q = discharge (gal/day) <br />T = transmissivity (gal/day/ft) <br />r = radius of the well (ft) <br />t = duration of pumping (days) <br />S = drawdown (ft) <br />S = storage coefficient (estimated 0.001) <br />The following sections discuss each of the monitored formations within the permit area and their <br />hydrogeologic characteristics. For the most part, the bedrock units represent the inactive <br />groundwater zone particularly at depths greater than about 500 feet below the ground surface <br />and a distance of approximately 1,000 feet inward from exposed cliff faces. The colluvium <br />and alluvium, along with the near surface exposures of the bedrock units, represent the active <br />groundwater zone. <br />Rollins Sandstone <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 />MCC has constructed four monitoring wells completed in the Rollins Sandstone. These wells <br />include R-l, LP-1, SOM-128-11, 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. <br />LP-1 was removed from the monitoring program in June 1998 when the Lone Pine Gulch <br />ventilation portals were closed and reclaimed. SOM-128-H and So.W-3 were also removed <br />from the monitoring program in 1999. Monitoring well So.W-3 was rendered useless when B <br />Seam mining cut through the well. <br />Considerable hydrogeologic parameter estimations have been conducted on the Rollins Sandstone <br />in the vicinity of the nine, particularly in the areas associated with the BEM and 14HG Faults. <br />As shown in Table 5, a pumping test conducted on monitoring hole R-1 for just the Rollins <br />Sandstone portion of the well indicates that the fonnation was capable of producing only <br />approximately 3 gpm. Mayo and Associates (1998) reports both horizontal and vertical <br />hydraulic conductivity values for various intervals within the Rollins Sandstone. In general, <br />10 horizontal hydraulic conductivity values range from 1.0 x 10-4 to 1.2 x 10-'" ft/d while measured <br />vertical values ranged from 1.7 x 104 to 1.8 x 10-2 ft/d. <br />2.04-63 Revised June 2005 PRIG, March 2006; Rev. April 2006 PRIO, Sep. 2007PR12