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adjacent to the mine access and haul roads. This test indicates the Rollins Sandstone has a very low <br />• transmissivity of 0.28 gpm/f t. A second slug test on UG 90-1, which is located in an F-Seam mine entry, indicated <br />that a[ this location the Rollins Sandstone had a transmissivity of 0.018 gpm/f t. <br />In the Jumbo Mountain area the groundwater head in the Rollins Sandstone is expected to be within one or two <br />feet of the top oT unit. Downdip from Jumbo Mountain, groundwater in the Rollins Sandstone may be under a <br />slight artesian pressure. <br />Finally, in the Jumbo Mountain area, the strata (interburden) between the B-Seam and the Rollins Sandstone <br />thickens considerably. As illustrated in Figure 2 which is across-section drawn down•dip trending southwest to <br />northeast on the eastern side of the Jumbo Mountain track, (Figure 31, the average thickness of the interburden <br />is about t 50 feet. Because of this amount of thickness, it is unlikely that mining activities in the Jumbo Mountain <br />area will affect the hydrogeologic character of the Rollins Sandstone. <br />3.0 HYDROCHEMISTRY <br />Table 3.1 presents water chemistry data from Wells SOM-128-H (Rollins Sandstone), JMB-12 (8-Seam) and Jumbo <br />1 Spring (Rollins Sandstone horizon). From this data, the Rollins Sandstone groundwater is considerably more <br />mineralized than that from the B-Seam or the Spring. The Rollins Sandstone has total dissolved solids <br />concentrations greater than 8,000 mg/I. This indicates that the unit has a very low permeability, that the <br />• groundwater in this unit has a high residence time, and that considerable salts have gone into solution. The higher <br />salt content in the Rollins Sandstone is also evident by the amount of salts deposited on the Rollins Sandstone <br />outcrops in the area. The fact that the that the spring water is considerably fresher with total dissolved solids less <br />than 500 mgA than the Rollins Sandstone water indicates that the spring discharge has a relatively short residence <br />time. The discharge tram the Rollins Sandstone, therefore, appears to make up little if any of the discharge water <br />from the spring. <br />. 4 <br />