2015-03-20_INSPECTION - M1980244

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PERMIT #: M -1980 -244 INSPECTOR'S INITIALS: TC1 INSPECTION DATE: March 11, 2015 OBSERVATIONS The Division conducted a monitoring inspection of the site on March 11, 2015. Marc Tidquist, represented the Operator during various parts of the inspection. Tim Cazier and Travis Marshall represented the Division. The focus of this inspection was to observe water levels, and initiate some discussion on numeric protection limits (NPLs), the new Squaw Gulch Valley Leach Facility (SGVLF) pump back system and reported slope instability in the Wildhorse Extension pit (WHEX). On Site Meetings: Meeting I: Mr. Tidquist explained additional area is needed for the blast stemming material crushing operation. The current location on the West Blue Overburden Storage Area (WBOSSA) has proven to have insufficient space for the 250,000 tons required. The mine plans to use the area in the South Cresson pit as a temporary location to crush and store an additional 200,000 tons of material. Due to the early January 2015 80% storage capacity exceedance in the Phase I PSSA, the Division is reviewing the need for monitoring the water levels in the PSSAs outside the influence of the cones of depression resulting from PSSA pumping. As there are PSSA water level transducers in the AGVLF Phase I, II and IV facilities, PSSA static water level monitoring in AGVLF Phase V and the new SGVLF were discussed. The Division understands that additional storage capacity is built into the AGVLF system, should the Phase V PSSA exceed 100% storage capacity in that overflow from the Phase V PSSA would be captured in the Phase I PSSA, and overflow from the Phase I PSSA would be captured by the Phase II PSSA. Currently there are no plans to install water level transducers in either the AGVLF Phase V or the SGVLF PSSA facilities. The Division will consider the need for each and inform CC &V of its decision. Meeting II: Mr. Lawrence Myers (CC &V) met with Mr. Marshall to discuss groundwater monitoring and Numeric Protection Levels (NPLs) as part of the Division's review of the background of both. The discussion focused on the furthest down gradient monitoring wells in Arequa Gulch (CRMW5A, B, C, & D). Mr. Myers indicated that these wells are not considered the point of compliance and that the wells are located outside of the permit boundary. The Division has no data for these wells due to it being located outside of the permit boundary and as such, Mr. Myers stated DRMS has no jurisdictional authority to request such data. The Division is currently reviewing the history related to the Arequa Gulch monitoring program. Mr. Myers also informed the Division that the NPL's for the wells acting as the point of compliance (CRMW -3A and CRMW -3B) was set and approved in Amendment 6. Meeting III: The Division met with CC &V Projects personnel to discuss the detailed designs for the SGVLF pumpback system which will pump water from the underdrain system back into the mine circuit. Mr. Ron Roberts (CC &V Projects Manager) and Andrea Meduna (Amec engineer) explained the concrete pumpback ponds will now act as overflow storage for the underdrain sump as opposed to acting as the sump itself. The Division expressed concerns about the monitoring program for the concrete ponds and the pressure rating for the pumpback system pipe, given the high static head required to pump the collected water back up to the SGVLF PSSA from the toe of the Hwy 67 realignment embankment. Ms. Meduna stated the proposed geosynthetic liner for the concrete ponds can accommodate significant elongation, allowing for seepage protection should the concrete crack. CC &V agreed to address these issues in a Technical Revision for the SGVLF pumpback system. CC &V also confirmed As- Constructed drawings of the pumpback system would be included in the next SGVLF CQA certification report. As- Constructed drawings of the pumpback system concrete ponds were submitted to the Division in January 2015 as part of the SGVLF PSSA CQA certification report. Page 2 of 8