2016-10-21_REPORT - M1980244 (32)

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Amec Foster Wheeler Environment & Infrastructure, Inc. 2000 S. Colorado Blvd., Suite 2-1000 Denver, CO 80222 Tel: +1 (303) 935-6505 Fax: +1 (303) 935-6575 amecfw.com 16 September 2016 Ron DiDonato Newmont Mining Corporation Post Office Box 191 Victor, Colorado 80860 Re: Structural Fill Monitoring for Phase 1 the Squaw Gulch Valley Leach Facility Dear Mr. DiDonato: Per Newmont Mining Corporation’s (Newmont) request, Amec Foster Wheeler Environment & Infrastructure, Inc. (Amec Foster Wheeler) has prepared this letter regarding temperature monitoring of soil liner fill (SLF) and structural fill at the Phase 1 Squaw Gulch Valley Leach Facility (SGVLF). The dates associated with the recorded temperatures discussed for SLF placement range from 2 December 2015 through 10 December 2015. However, it should be noted, as per the footnote on Table 2 attached, Amec Foster Wheeler did not certify the SLF placed during these dates because the placement of liner and DCF was not completed while Amec Foster Wheeler was the Quality Assurance consultant. Temperature readings for SLF using a thermometer are possible because it is fine grained material, thereby allowing a thermometer to be inserted at different depths to accurately measure temperature. Temperature readings in SLF were typically recorded at 3 inches and 6 inches below the fill surface per the project specifications. SLF was placed in Phase 1 of the SGVLF until 10 December 2015. Between 11 December 2015 and 29 February 2016, no SLF material was placed. Amec Foster Wheeler was no longer responsible for Quality Assurance testing for SLF material placed after 29 February 2016. We have attached Table 2 - Fill Temperature Monitoring Summary from the Squaw Gulch Valley Leach Facility Phase 1 (9,550-foot Elevation Bench to Geomembrane Panel P1635 dated January 2016) record of construction report. The footnote on page two outlines that the SLF material placed on the indicated days was not certified with the record of construction report; however, it does indicate that the material placed during that time was above freezing. Final approval of the SLF and geomembrane materials of the indicated dates was to be certified by the succeeding Quality Assurance consultant. Any removal and replacement of SLF or geomembrane materials after 29 February 2016 was not monitored by Amec Foster Wheeler staff. Structural fill is typically composed of rocky material, with more than 30 percent of the material over ¾ inch rock size. As indicated in Section 02200 Earthwork, Subsection 3.06, Item B of the Project Specifications, structural fill materials placed containing more than 30 percent rock materials over ¾ inch require a method compaction technique. Because of the rocky material and the method compaction, neither nuclear density testing nor temperature monitoring with a thermometer are possible.