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STATE OF COLORADO DIVISION OF MINERALS AND GEOLOGY Depanmem of Ivamral Resources I i I l Sherman SL, Koom 215 Denver, Colorado U0203 Phone 14031 Hbb-75h7 FA%: 1307) N1?-H 106 DATE: March 2l, 1997 TO: ~ Bill Carter FROM: Susan Burgmaier~ RE: Sanborn Creek Mine (C-S1-022) 1996 Annual Hydrology Report II~~ DEPARTMENT OF ' NATURAL RESOURCES- Roy Romer Governor lames 5. Luchhead Exec W rve Dirp(•1or Michael H. Long Drvisian Director I have completed a review of the 1996 Annual Hydrology Report (AHR) for the Sanborn Creek Mine. I reviewed the report itself, previous AHR's back through 1990, and the permit applications it pertains to baseline hydrology and the prediction of probable hydrologic consequences (1~EIC). Following aze my resulting comments and questions for the operator. 1. With a few exceptions, all required monitoring was completed. Exceptions noted were: a. The text of the AHR notes that Site WSC DH12 was not monitored in 1996 because the low water level and well depth prohibit bailing and sampling. OCM notes that a power bailer will be built to make sampling of the well easrer. OCM should make sure that whatever necessary equipment for monitoring is on line for the required June sampling this yeaz. b. Full suite analyses were not done during the second quarter at sites S-1, S-2, C-1, and HN-1. OCM notes that the full suite analyses were scheduled for June, during which no flows were observed. The monitoring plan requires quarterly full suite analyses, and has not been approved for a specific month only. Because there was flow during the second quarter, OCM should have obtained samples to be analyzed for the full parameter suite. Please make an effort to ensure that all involved staff are awaze of this requirement so that samples will not be missed in the future. c. The third quarter full suite was missed at Site T-1 for the same reason noted in Item b., above. This information would have been especially important for this site, since 1996 data constitutes baseline data. 2. Field conductivity values rise significantly between Site S-] and S-2 for the April and May data (80 utnhos/cm to 480 umhos/cm in April, 90 to 800 in May). No mention of these results is made in the report text. How does OCM explain this increase? 3. Since 1990, total dissolved solids (TDS) values have risen steadily at Site SC-l. No mention or explanation is made in the AHR text. Does OCM have any explanation for this increase? Monitoring data for 1996 shows TDS values increasing between NF-t and NF-2, the upstream and downstream monitoring sites on the North Fork of the Gunnison River. No discussion is made as to what might be causing this increaser [t is possible that the Bumping of water in the mine to decrease total suspended solids is contributing to increased TDS in the minewater discharge, which would elevate TDS in the North Fork. Has OCM looked into the TDS increase?