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' Memorandum to Kathy Welt <br />June 10, 1998 <br />Page 5 <br />' (since a travel time of thousands of yeazs from the sump to the spring is not an option at <br />the site). In the West Elk and Bear mine environment, we would not expect to find very <br />old dilution water that has low TDS and Na` concentrations and, also, a very negative <br />1 S"C. <br />Water Temperature <br />The temperature of water in the WEM sump is about 17.4°C to 23°C, whereas the water <br />discharging from the Edwazds Portal spring is higher, about 28°C to 29°C (Tables 1 and <br />3). The higher temperature of the spring water cannot be attributed to thermal water in <br />the sump. There is evidence of spontaneous combustion within the Beaz Mine, which <br />would serve to heat water from any source. <br />' CONCLUSIONS <br />The water quality and isotope data presented rules out the possibility that all of the water <br />issuing from the Edwards Portal spring can originate from the WEM sump. Two <br />possibilities then remain: <br />' 1. Part of the water flowing from the spring comes from the sump and part comes <br />' from other sources. <br />2. None of the water flowing from the spring comes from the sump. All of it comes <br />from other sources. <br />Based on the evidence, either scenario is theoretically possible. However, for the first <br />' case, the data show that any contribution from the WEM sump must be much smaller <br />than the contribution from other sources. In summary, the data leading to this conclusion <br />are: <br />' 1. The much higher levels of TDS and Na` in the WEM sump water, as compazed to <br />the Edwazds Portal spring water, require appreciable dilution with low TDS and <br />' Na' water from anon-WEM water source. Mineral precipitation or ion-exchange <br />are not plausible mechanisms to reduce either of these parameters. <br />2. Differences in the S"C contenu between the sump and the spring waters require <br />fundamentally different carbon sources. Dilution is not a reasonable alternative <br />because, a) the HCO~ content of sump water is about twice as great as water from <br />' the spring, and b) the S"C composition of the required dilution water would have <br />to be appreciably more negative than -13 °/~. There are no plausible sources of <br />such dilution water. <br />' 3. Differences in the "C contents of the sump and spring waters require that water in <br />the Bear Mine-Edwards Mine complex be diluted with very old groundwater. In <br />