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<br /> <br />definition of an underground source of drinking water (USDW) in 40 CFR Part ]44.3 and <br />concludes that the only USDW in the project area is in the upper part of the upper Aquifer in <br />the Uinta Formation (p. G-8). This conclusion relies in part on aTDS-conductivity <br />relationship but evidence for this relationship was not supplied with the application materials. <br />The evidence was also based on a qualitative assessment of actual TDS values for samples <br />where TDS and conductivity did not agree due to analytical error. However, there are not <br />enough data in [he application to define changes in water quality, stratigraphically, with such <br />precision that all of the upper Green River can be excluded as a USDW, or for that matter <br />that all of the lower Uinta can be included as a USDW. <br />The operator should provide more information on groundwater quality. There should be <br />enough information to characterize the relationship between TDS and conductivity, and if <br />conductivity is to be used to interpret TDS, and hence the stratigraphic limits of the USDW, <br />then the conductivity logs should be part of the permit application. The operator reliance on <br />qualitative judgements about TDS should be shored up with more quantitative measures. <br />2. Page D-13 forward. Although the mining plan appears to presume that the solution cavities <br />will be mostly symmetrical around the solution well pipe in the Saline Formation, it is likely <br />that fractures, faults, other lateral discontinuities, and inhomogeneities in some strata of the <br />Saline Formation will lead to production of solution cavities that are laterally asymmetrical. <br />Lithologic variations it is acknowledged will promote greater dissolution and calving in some <br />zones than in others. Thus, the shape of the solution cavity cannot be determined from <br />product volume alone, and hence the maximum lateral extent of each cavity cannot be <br />determined from product volume. The operator should demonstrate what steps may be taken <br />to preclude intraformational contact between solution cavities. <br />3. Page G-3 and forward. The text on page G-3 indicates that the lower aquifer has a variable <br />TDS and metals content. The text on page G-4 however indicates that the lower aquifer <br />"does not meet the standard for drinking water because of marginal pH and high <br />concentrations of various elements. While it might be protective of the company's interests <br />to identify what portions of the lower aquifer are potable and what portions aze not, both in <br />the vertical and aerial sense, we would ask that [he mining and groundwater monitoring and <br />compliance plans instead address how the potable portions will be protected. American Soda <br />should indicate what protective measures will be taken to prevent contamination, and how <br />non-compliant monitoring results will be addressed. <br />4. Page D-6; section D.2.4.1. The text indicates that some evaporation will take place at the <br />Piceance site prior to placement of process waters in the pipeline to the Parachute facility. <br />Presumably, this will take place in the Piceance Site Pond. The DMG needs [o know more <br />about the Piceance Site Pond. What is its function? What types of fluids and solutes will it <br />contain? Is it a high temperature pond, and in that regard what protections may be needed to <br />prevent access to humans or wildlife? What will be the composition of the pond residues <br />and how will those residues be managed? Amore detailed explanation of the processing <br />might answer these questions. <br />3 <br />