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use, <br />~~cmcx <br />October 29, 2007 <br />Dos. Erica Crosby <br />Environmental Pxotecdon Specialist <br />Division of Reclamation, Mining and Safety <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />R~C~I\/E~ <br />OCT 3 12001 <br />DivMiningfandcSafety n, <br />Re: CEMEX Lyons Mine Permit M-1977-208 <br />~esponse to 10-5-07 Adequacy Review Letter <br />Technical Revision No. 9, C-Pit Hydxogeologic Investigations <br />Dear Ms. Crosby: <br />This letter addresses the four issues raised in the Division's Adequacy Review letter to <br />CEMEX of October ~, 2007. The DRMS' comments/questions are repeated below, <br />followed by CEMEX's response. <br />1. Please find attached comments regarding the hydrogeologic investigation and changes to <br />the ground water monitoring program at the site. The following discussion is in response to David <br />Bird's October 72, 1007 memorandum to Erica Crorby.: <br />a. Reduction of sampling frequency for C-Pit Water from quarterly to semi- <br />annually. <br />Due to the history of constituents in pit water at concentrations exceeding <br />regulatory limits, DRMS should require a[ least five quarters of analyses with <br />results below regulatory limits before approving this proposal. <br />CEMEX Response: CEMEX will continue to sample CPit water forfzve consecutive quarters. At the <br />completion of this period, CEMEX will consider proposing a different sampling schedule to DBMS, <br />dependang upon the results for C-Pit, as well ar the data from the moreitonng well neturork. The fern <br />quarterly sample widl be taken in October 2007. <br />b. Eliminate dissolved thallium and chloride from the analyte list. <br />Because of the history of thallium and chloride detections at the site, eliminating <br />thallium and chloride from the analyte suite would be premature. Thallium and <br />chloride axe regulated parameters, and should therefore be analyzed fox five <br />quarters, with results below regulatory limits, before DRMS approves their <br />removal from the analyte suite. <br />Lyons Planf <br />p0. Box 529, Lyans, CO 80540. USA, (303) 823-2100, Fax (303) &32-2199 <br />~~ ~~~9 <br />Draft Response to 10-5-07 Adequacy Review_'1'R-9_REV2 <br />