2012-07-19_INSPECTION - M1990057

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PERMIT #: M- 1990 -057 INSPECTOR'S INITIALS: MAC INSPECTION DATE: July 10, 2012 OBSERVATIONS The inspection was conducted by Michael Cunningham of the Division of Reclamation, Mining and Safety (Division). Mike Elder, Steve Craig and Ken Curfman of The Union Milling Company were present for the inspection. The Hopemore Shaft site is comprised of the Hopemore Shaft, which is operated as a tourist mine, and the Union Mill. The mill and mine site are on non - contiguous parcels of land in Lake County, Colorado. The mine site is located 3.3 miles east of Leadville and the mill is located approximately 2 miles south of Leadville off Highway 24. The overall site is permitted for 8.5 acres; the mine is permitted for 1.9 acres and the mill is permitted for 6.6 acres. The purpose of this inspection was to monitor the progress of the construction of the tailings storage facility (TSF) at the mill site, which was approved under Technical Revision No. 3. The inspection did not include a visit to the mine site; the mine site will be inspected during the next regular monitoring inspection. Backfilling and Grading: The Operator is constructing a new TSF, which encompasses the footprint of the original unlined TSF. Approximately 100 tons of magnetite and 1,000 st of historic tailings were removed from the original TSF and placed onto a temporary clay pad located immediately south of the mill building. The material is currently surrounded by a silt fence and is covered with visqueen; the material will be returned to the TSF when construction is complete. The Operator is currently working on impoundment excavation and embankment construction of the TSF. The site has been cleared of vegetation including tree roots and dead wood. The topsoil has been removed and stockpiled to the east of the TSF. The TSF has been excavated to a depth of approximately 25'. The interior side slopes of the TSF are not to final grade and are covered with large cobble. The Operator will track over this material to compact it into the side slopes prior to the installation of the clay liner. The Division observed the Operator placing fill material onto the top of the TSF embankments. The fill was being placed in 10 -12 inch lifts. Ken Curfman, the onsite construction engineer, was overseeing the placement of the fill material. The lifts are compacted with a sheep foot roller and are placed at 95% of Standard Proctor dry density. In addition, Mr. Curfman was performing moisture tests of the fill to ensure that the fill was moisture conditioned to within 2% of optimum. Fill material that is too dry is wetted to bring it within 2% of optimum and fill material that is too wet is allowed to dry out before it is placed on the embankment. The Division reviewed the QA /QC forms which are filled out daily; the CIA /QC Plan is being adhered to. The Operator has contracted with a surveyor to come out every other day to monitor the embankment and interior slope construction. The Operator estimates that excavation and embankment construction will be complete in 1 -2 weeks. Following the completion of the embankment construction, the sump pump will be installed in the northwest corner of the TSF. The approved construction plan for the TSF calls for installing a 12 inch clay under liner which is to be placed on the interior slopes and impoundment bottom. The Operator notified the Division that the native onsite clays which were to be used for the liner were not present in sufficient quantities to construct the liner. The Operator is proposing to use Bentomat, a geosynthetic clay liner, in place of the native clay material. The Operator is aware that a Technical Revision must be submitted to address this change in the construction plan. Page 2 of 5