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Christine Johnston Mountain Coal Company Page 2 November 12, 1997 occur during discharge of Ponds MB-l and MB-2R. The Division recommends that MCC should attempt to present the most accurate analysis of potential impacts to the North Fork of the Gunnison River possible by 1) presenting actual data collected from the lower station and 2) collecting samples from the lower station during discharge or soon after the primary site ponds MB-1 and MB-2R have been discharged and mixing has occurred. In addition, if MCC is aware of other specific sources for constituent contributions to the North Fork of the Gunnison River, then these should be presented and discussed in the AHR. 6. Please update Table 15 with the revised calculations for the CHIA analysis based on the Division's review of Technical Revision #80. Please refer to the Division's adequacy review letter for Technical Revision #80 dated August 13, 1997 (questions #39 and #40). For future AHRs, discharges from all site ponds including (MB-l, MB-2R, MB-3, WWTP, MB-5) and any other sources that may contribute to salt loading in the North Fork of the Gunnison River should be included in the CHIA analysis. Other potential sources may include mine water dischazges to the North Fork of the Gunnison River. 7. The Division agrees with MCC's interpretation on page 36 of the AHR that the statement concerning impacts to springs needs to be modified in permit text (page 2.05-130 and repeated in various other locations). This may be accomplished as part of the TR-80 review process or as a minor revision to the permit document. No response from MCC is necessary at this time. 8. The Division recommends that the groundwater monitoring network of wells be assessed to ensure that adequate and meaningful data are being collected. On page 37 of the AHR, MCC indicates that 8 wells had insufficient water to obtain water level readings, 6 wells had insufficient water to obtain water quality samples, and 3 wells are damaged so as to not allow water quality sampling. Two of the 14 wells that are stated to have insufficient water, show both an adequate well casing volume and an overall increase in water level since their initial installation. These wells include GP-5, and SO.W-3. Please provide clarification as to why water samples were not collected from these wells during the third sampling period. MCC further states that an inadequate amount of groundwater in wells is consistent with the general lack of groundwater within the Mesa Verde Formation. This may be the case; however, the Division recommends giving consideration to installing wells at these locations deeper into the saturated interval/formation that is being monitored. [f water levels are declining, then deeper screened intervals may provide adequate water for obtaining a sample. The Division also recommends replacing damaged wells so as to allow for water quality sampling at locations where well casings have been bent or sheazed.