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f1cf, <br />? mcx <br />October 24, 2008 <br />Mr. David Bir111", <br />Environmental Protection Specialist <br />Division of Reclamation, Mining and Safety <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />OCT 2 7 2008 <br />Division or -reclamation, <br />Alining and Safety <br />Via Certified Mail 7007 2680 0001 6365 8670 <br />Retum Receipt Requested <br />Re: CEMEX Lyons Mine Permit M-1977-208 <br />Technical Revision No. 9, C-Pit Hydrogeologic Investigations <br />3rd Quarter 2008 Monitoring Data <br />Dear Mr. Bird: <br />This letter transmits surface water and groundwater data from sampling the C-Pit pond and <br />related wells, in keeping with the requirements of Technical Revision No. 9 to Permit No. M- <br />1977-208. <br />On August 20, 2008, CEMEX sampled the water in the pool at the north end of C-Pit, as well as <br />groundwater from monitoring well CEM-001, the nearest well, and the alluvial well, CEM-004. <br />CEMEX continues to monitor the water elevation in C-Pit and in CEM-001, and to measure the <br />depth to water in compliance well CEM-005 located approximately 2,700 feet southeast of C-Pit <br />along Hygiene Road. Refer to the text, figures, and appendices of the C-Pit Hydrogeologic <br />Investigations report (Brown and Caldwell, August 31, 2007) for site details, well construction, <br />and related information. <br />Analytical Data <br />The C-Pit pond water and groundwater samples taken on August 20 were analyzed for pH, <br />dissolved selenium, dissolved thallium, chloride, sulfate, and dissolved solids. Table 1 <br />summarizes the results, and the most recent analytical laboratory reports are enclosed with this <br />letter as an attachment. <br />Water Elevation <br />CEMEX continues to monitor the water elevation in the C-Pit pond by using a data logger to <br />record head data. Another data logger is installed in CEM-003. Data is downloaded quarterly, <br />and maintained for informational purposes incase conditions change in the future. <br />Measurement of the depth to water at compliance well CEM-005 on August, 2008 confirmed <br />that this well continues to show no significant change since it was drilled in May 2007. The 400- <br />foot deep well has almost no standing water, which CEMEX believes reflects residual water <br />from well development. As agreed upon in TR-9, we will continue to monitor the depth to water <br />Lyons Plant <br />P.O. Box 529, Lyons, CO 80540. USA, (303) 823-2100, Fax (303) 832-2199