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<br />Page 4 <br /> <br />C> <br />1"-' <br />W <br />Q) <br /> <br />consistent with the responses described above. The average transmissivity and storativity from <br />various analyses of the two tests are 450,000 gpd/ft (60,000 ff/day) and between 10-3 and 10'4, <br />respectively. For comparison, aquifers with transmissivities greater than 100,000 gpd/ft <br />"represent good aquifers for water well exploitation" (Freeze and Cherry, 1979). These results <br />are consistent with the estimated high flows from the Leadville to the Colorado River. <br /> <br />The various observations described above suggest that the Glenwood Springs area is a major <br />discharge area for the Leadville Limestone aquifer. This is probably a result of the serendipitous <br />intersection of several structures, the Leadville Limestone, and the relatively low land surface <br />elevation with respect to the surrounding area. Several investigators also conclude that this is <br />a major discharge area for the Leadville. <br /> <br />2.2 CONCEPTUAL MODEL <br /> <br />Superficially, the Glenwood Springs geothermal system is an enigma with respect to its high <br />flow rate and high salinity. Any conceptual model must consider the very high flows (and <br />transmissivities), relatively high salinity, the artesian head, and of course the elevated <br />temperature. <br /> <br />Surface and subsurface observations clearly indicate that the conduit for the high flows is the <br />Leadville Limestone. However, the lithology of the Leadville is inconsistent with the observed <br />sodium chloride salinity of the groundwater. The likely source of the sodium chloride is the <br />evaporite sequence in the Eagle Valley Evaporite, which is located stratigraphically above the <br />Leadville. In order to "support" the high flow rate at the discharge area, the recharge area <br />either must be very large or have similar hydraulic conductivities. The evaporite deposits could <br />have similar hydraulic conductivities due to solution channeling, but in general are inherently <br />tighter materials. Between the evaporites and the Leadville is the Belden Shale which is likely <br /> <br />Michael J. Galloway <br />Consulllng Hydrogeolaglst <br /> <br />Project 1016 <br />