2016-07-21_REVISION - M1980244 (4)

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A m NewFields Perspective.Vision. Solutions. TECHNICAL MEMORANDUM 9400 Station Street Suite 300 Lone Tree,CO 80124 T:720.508.3300 F:720.508.3339 To: Tamara Baker, Senior Environmental Coordinator From: Jay Moore & Nick Rocco Project: Cripple Creek&Victor Gold Mine Project No: 475.0106.008 Subject: Stability Evaluation for Arequa Gulch VLF—Mill Solution Injection Program Date: 12 July 2016 .......................................................................................................................................................................................................................................... Newmont Mining Corporation (Newmont) retained NewFields to review the stability of the Arequa Gulch Valley Leach Facility (AGVLF) at the Cripple Creek &Victor Gold Mine (CC&V), and to identify if the proposed mill solution injection program would compromise the facility slopes. The proposed injection program is similar to the existing Hydro-JexT"" injection program used at the site with the exception that fluid pressures within the proposed injection wells will be hydrostatic and not pressurized. This technical memorandum presents a brief overview of the mill solution injection program,the stability evaluation, and our recommendations. 1.0 MILL SOLUTION INJECTION PROGRAM Based on information provided by CC&V, the proposed mill solution injection program would utilize one of two wells in the Phase IV area of the AGVLF for injection of excess mill water. Each well is approximately 190-foot in length, open at the bottom, and perforated from 20-feet below the ore surface to the bottom of the well. The base of the wells maintain a 100-foot buffer from the base liner, at a minimum. The location of the two wells, well #1001 and #1002, are shown on Figure 1. Mill water will be pumped to the wells using a 4-inch, HDPE pipe at a rate of approximately 100 gallons per minute (GPM), on average. Solution will be directed into only one well at a time, and can be turned off to ensure excess pressure does not develop.