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Homestake 2014 Geotechnical Observations <br />Pitch Reclamation Project Indian and Tie Camp Waste Rock Dumps <br />2. Tie Camp Waste Rock Dump <br />a) "10400-10100" Level <br />Site Description: The Tie Camp rock dump was re- graded in 1994 following procedures <br />approved in the February 1994 Technical Revision. During 1995, minor, localized areas <br />of slope instability were noted, corrected, and reported in the 1995 Annual Geotechnical <br />Report. <br />2014 Observations: Piezometer TC10375 monitors the Tie Camp rock dump. In 2013, <br />water levels averaged 168.6 feet bgs, with a maximum observed seasonal fluctuation of <br />4.2 feet between May and June. The maximum fluctuation was higher than the 2.4 feet <br />recorded in 2012, but well below the 2008 rise of 12.3 feet, when the site incurred heavy <br />snow pack. <br />In 2014, the water level in TC10375 increased by 9.1 feet between January and July. <br />The water level in December was near the seasonal low having dropped by 1.5 feet to <br />10203.8 feet amsl. This is deemed a normal and acceptable seasonal variation. <br />Field observations indicate that the repairs performed in 1995 were successful and no <br />new areas of surficial instability were observed from 1996 through 2014. In 2012, <br />grading was performed on the second and third benches from the top of the rock dump <br />to control rill erosion that had become apparent over the past couple of years due to the <br />benches filling with silt. This repair work was described in the 2012 Annual Reclamation <br />Report. In 2014, we will continue to monitor the surface conditions of the rock dump <br />after the spring snow melt. <br />3. Piezometers - 2014 General Comments <br />In general, the peak water levels in the rock dump piezometers reflected the heavier <br />than typical snow pack of 2014, and the December water levels did not fall back to <br />seasonal lows due to heavier than typical late summer rains. The 2014 water level <br />measurements showed a maximum differential following snow melt above the 2013 and <br />much higher than 2012 measurements, but below that of the previous five years due to <br />differences in snow pack and summer precipitation. Following the dry conditions of 2001 <br />through 2003, the seasonal variations had increased in recent years as heavier snow <br />packs had occurred, with 2012 being a relatively dry year. The replacement of two <br />piezometers in the Indian Rock Dump in 2011 has alleviated siltation issues in <br />monitoring the phreatic surface in the Indian Rock Dump. We will continue to monitor <br />and evaluate the cause and effect of any seasonal spikes in the piezometric water <br />levels, observe any changes in surface features of the rock dumps and repair as <br />needed. There continues to be no indication of concern related to slope or foundation <br />instability or elevated phreatic surfaces in either the Indian Creek or Tie Camp Creek <br />Rock Dumps. <br />Homestake Pitch Reclamation Project Page 4 <br />2014 Annual Geotechnical Report December 23, 2014 <br />M- 1977 -004HR 2014AnnualGeotechnicalReportText _Final.doc <br />