2011-09-27_REVISION - M1990057 (10)

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water conditions. After a short period of time, the water migrates to areas lower in the colluvium/alluvium and no perched water is observed in the monitoring or tests holes. UMC has not observed artesian flows from the above wells or any evidence of movement of water in any wells resulting from adjacent hydrostatic pressures in the area. The waters are unconfined, leading to the temporary perched water condition, and there is no water gradient. The excavation of the TSF will disrupt portions of the colluvium/alluvium structure and the perched water conditions within the excavation. Excavation is anticipated to expose clay overlaying gravel lens, clayey gravels and clayey sands. The high permeability materials will be removed and segregated as material for stockpile and/or other fill operations not associated with the TSF construction. The low permeability clays will be removed and segregated for use in the clay liner. Should a gravel lens be exposed in the bottom or sides of the excavation, the lens will be over excavated to 3 feet, backfilled and compacted with clay liner material to block the water conduit. The initial excavation cut and fill operation, material stockpiling, embankment placements and other similar operations will be under the observation and supervision of either a geotechnical engineer /technician or UMC's owner engineer. It is anticipated that there will be 110 groundwater discharges. If groundwater is encountered during construction and cannot be infiltrated on site, UMC will apply for a Groundwater Discharge Permit from the State of Colorado Department of Public Health and Environment and notify the Division that the ground conditions are other than anticipated. The TSF liner system is designed to protect the temporary perched water conditions with a 12in clay liner, leak detection system and the 45mi1 polypropylene geomembrane liner. The TSF, as designed, is a 2 -way barrier, maintaining the tailings within the impoundment and maintaining temporary perched water conditions outside the impoundment. The leak detection system is also a 2 -way safety system, indicating the structural integrity of the 45mi1 liner and indicating the structural integrity of the clay liner. Fluid detected by the leak detection system can be clearly identified as either tailings fluids or groundwater fluids. The TSF was designed as a zero discharge facility. Non disturbed drainage is diverted around the TSF while disturbed area drainage from the mill area disturbance reports to the TSF. An observation well exists down gradient from the 4.6 acre TSF area. CTL/ Thompson constructed an observation (monitoring) well for the TSF area. This April 10, 1990 report, Installation of Observation Hole, is presented as Appendix D. This observation well is shown on Exhibit MLR -1. In October 2001, Leadville Mining and Milling Inc. provided a commitment to CDRMS that the mill would not dispose of any additional mine tailings or other mine related material in the tailing pond until LMMI provides information concerning four conditions to the permit. The conditions included: water rights, air permit for the mill, water monitoring, surface water diversions ditching calculations, and tailing pond compaction results. Current Operations The current mill configuration, process and operations have been modified to treat a different ore than was processed during the last operational period, as described above in the section titled MILL DESIGN AND CAPACITY. This necessitates rephrasing the initial TSF plan to provide M1990 -057 September 27, 2011