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Erica Crosby- CDMG ENV 234.04 October 12, 2004 Page 2 monitoring a natural system so we suggest that the verification sampling schedule proposed in TR-#4 would need to remain as provided. Please accept the submittal of these graphs as we have discussed as substitution for Appendix B in TR-#4. Also please consider updated Table 9 with these values based upon statistical analysis of the operational data and not the Dixon calculation of the 15-month baseline data. 2. Collection of BTEX samples in the production lines. Response: Since no production fluid is available during temporary suspension of production operations, it will not be possible to collect production samples. American Soda intends to resume monthly BTEX samples on the production lines once commercial production resumes. 3. Removal of Barium from the list of parameters monitored. Response: American Soda proposes to remove Barium from the list of parameters monitored because the data is indicating that Barium concentrations vary with location of a well rather than zone of an aquifer or production stream. In several instances, the ground water monitoring wells in the upper aquifers have concentrations that are consistently higher than those observed in the production streams or the lower aquifers. In the Dissolved Barium Concentration graph provided in Appendix C of TR-#4 the concentration of dissolved barium in Upper Aquifer Uinta well 21-4U and Uinta well 21-3U are both consistently higher than the lower aquifers and the production streams. Generally, the same is true of Well 20-9 (B Groove), Well 29-3 (A Groove), Well 29-4B ("Up-gradient" B Groove) If barium were used as an indicator of water migration out of a solution mining cavity it would not be a reliable indicator because there is no clear distinction between some of the aquifers and the production streams. The other metals proposed for retention in the monitoring program (Potassium, Sodium, Silica, Boron, and Lithium) all provide a much clearer distinction between the ambient ground water and the source or solution mining brine regardless of the aquifer. Having a target population with a greater concentration of the constituent than the source seems capable of providing would make it difficult to meet the need for ground water protection. Dissolved barium does appear to be slightly increasing in a few of the lower aquifer wells. This is true of the baseline time period and the operational time period. It does not seem to correspond with solution mining activities. It relates more to the monitoring wells themselves for example with Well 19- 2 it is believed that dissolved Barium is a result of the drilling activity. This is the only location were small amounts of barium was potentially introduced to the well since it may have been contained in materials used to stem the flow of methane gas from the well when it caught fire during drilling. American Soda's drilling program,'as suggested by Dr. George Salunier, used a synthetic polymer in the drilling mud rather than barium containing drilling mud for all ground water and production well drilling. In the open-file report 78-734, Geohydrologic Data from Twenty-Four Test Holes Drilled in the Piceance Basin, Rio Blanco County, Colorado 1975 - 76, Frank A. Welder and George J. Saulnier, Jr., U. S. Geological Survey (prepared in cooperation with the U. S. Bureau of Land Management and the U. S. Environmental Protection Agency) the concentrations of dissolved barium are varied throughout the basin. At some of these locations, in aquifers as high as the Uinta, the barium concentrations in the test holes is greater than what we have observed from our production streams. From letter dated Octoberl3, 2004 requesting additional clarification. 7. Some of the data collected during the baseline period reflect an unstable baseline.