2010-12-20_INSPECTION - M1977208

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PERMIT #: M-1977-208 INSPECTOR'S INITIALS: MAC INSPECTION DATE: December 3, 2010 OBSERVATIONS The inspection was conducted by Michael Cunningham of the Division of Reclamation, Mining and Safety (Division). Pat Fischer, Denise Arthur, and Melissa Mele of CEMEX, Inc. were also present for the inspection. The Lyons Quarry is located approximately 2 miles east of Lyons, Colorado. The site is permitted for 979.54 acres and the post-mining land use is rangeland. The purpose of this inspection was to monitor the progress of backfilling of cement kiln dust (CKD) into the C-Pit:. The backfilling of CKD into C-Pit and the associated groundwater monitoring have been addressed through the following Technical Revisions: TR - 04: Approval of plan to place CKD into C-Pit and approval of sampling, analysis, and reporting plan for groundwater compliance points. TR - 06: Submittted as a stipultation to TR-04. Approval of revised plan to pump C-Pit water for consumptive use in the CEMEX cement plant. TR - 07: Approval of biological treatment method for the removal of selenium. TR - 08: Approval of hydrogeologic investigations and installation of compliance well. TR - 09: Approval of plan to continue sampling C-Pit for 5 Quarters, continued monitoring of dissolved thallium and chloride, continued monitoring of water level in C-Pit, continued sampling of CEM-001 for 5 Quarters with Thallium added to the analyte list, continued monitoring of water levels in CEM-005, continued monitoring of wildlife in C-Pit, and disposal of spent kiln refractory brick into C-Pit. TR - 10: Approval to discontinue wildlife monitoring in C-Pit. The Division also discussed the forthcoming TR-11 with the CEMEX representatives. Under TR-09, CEMEX was to continue the groundwater sampling program for an additional 5 Quarters. CEMEX fulfilled the groundwater monitoring requirements and continued to sample/monitor beyond the required 5 Quarters. The purpose of TR-I 1 shall be to compile the groundwater sampling and monitoring data into a single report, with the data being analyzed for trends. In addition, TR-11 should provide a revised timeline for completing backfilling of the C-Pit as well as a revised groundwater and surface water monitoring/sampling plan. Reclamation Success: The CEMEX cement plant was non-operational at the time of the inspection. The personnel at the site is kept to the minimum amount required until the cement plant resumes operation. The C-Pit was visited during the inspection; no backfilling was taking place. CEMEX is able to control the water level in the C-Pit by pumping water, via a floating pump, from the C-Pit to the cement plant. The C-Pit was not being pumped during the inspection; pumping last occured approximately 3 weeks ago. The water in C-Pit is ponded at the northeast corner of the pit. Based on visual observations, there is between 10' - 12' of freeboard in the pit and the surface area of water is approximately 0.5 acres. The depth of water at the time of the inspection is not known. According to Mr. Fischer, the last time the pit was pumped, the pump bottomed out, which indicates portions of the pit floor are between 3' -- 4' from the water surface. The western highwall in the C-Pit was inspected and was found to be seeping water in several locations. The water was seeping at nominal rate and was no more than a trickle. The Boulder Feeder Canal, to the west of the C-Pit was also inspected. The Boulder Feeder Canal was not flowing during the inspection. The area around the 54" culvert which runs under the Boulder Feeder Canal had saturated conditions at the ground surface as evidenced by standing water and hydrophytic vegetation. The saturated ground conditions indicate a high water table in this area which may be contributing to the inflow of water into C-Pit. This concluded the inspection. Page 2 of 4