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<br />Mr. Rick Mills - 2 - <br />May 26, 1987 <br />The Division is quite concerned about the quality of the bedrock wells at <br />Foidel Creek, as TCC is well aware. In evaluating the 1986 AHR, the staff <br />closely examined the results from 006-82-48A and 006-82-48, a Twentymile and <br />Wadge well, respectively. These wells are the only wells which are heing <br />carried through in the recently approved hydrologic monitoring plan. Neither <br />of these wells have produced replicate historical water quality data. <br />Although these wells were designed as compliance monitoring wells to register <br />the impact from mining, no impacts were projected for these sites at this <br />time. Please discuss the variability observed. Include a discussion on the <br />impacts of sampling methods on water quality data, and suggest a method for <br />correlating the results acquired at any one site. <br />The 1986-1987 water year AHR will be used extensively for the Permit Renewal, <br />which will be issued in May, 1988. In anticipation of this re-evaluation of <br />water data collected to date, it would be beneficial if a potentiometric <br />drawdown map could be prepared to verify previous assumptions. In addition <br />the Division would like to see a comparison between actual surface and <br />alluvial well water salinity data and the analytical rationale utilized during <br />the life-of-mine permit revision to estimate salt loading in sub-irrigated and <br />flood irrigated alluvial valley floors. <br />The 1986 revised AHR was significantly improved over previous AHRs. A large <br />number of figures were included which graphically documented hydrographs anc <br />changes in water quality over time. The juxtaposition of upstream and <br />downstream data from Fish and Foidel Creek surface sites was very effective. <br />The statistical summaries of data was useful of evaluating impact during <br />1986. Future statistical summaries could be improved by adding flow <br />statistics to the summary. <br />The Division appreciates the large effort which went into the compilation of <br />all the historic data collected to date on the Cyprus properties in Routt <br />County. The Division commends Mr. Nalven on his painstaking research to <br />ascertain the_form of metals analyzed during the past seven years amidst <br />considerable regulatory inconsistency and multiple transfers of mine <br />ownership. However, future AHRs need only report the historic data for sites <br />within each permit's hydrologic monitoring plan. The Division requests that <br />future data compilations be either paginated with a Table of Contents or that <br />sites be tabbed and segregated from one another. <br />Please address the questions concerning the bedrock wells by July 15, 1987, <br />and contact me if you should have any questions. <br />Sincerely, <br />~'r~`~~/~.~ C~J ~1~ <br />Catherine W. Begej ~ <br />Reclamation Specialist <br />CWB/lal <br />Enclosure(s) <br />cc: Brent Anderson <br />9991 F <br />