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Homestake <br />2015 Geotechnical Observations <br />Pitch Reclamation Project Indian Creek and Tie Camp Waste Rock Dumps <br />Homestake Pitch Reclamation Project <br />2015 Geotechnical Observations <br />Indian and Tie Camp Rock Dumps <br />1. Indian Creek Rock Dump <br />a) "10800" Level <br />Site Description: Identical to that of past reports for 1996 through 2014. <br />2015 Observations: The 2015 observations are similar to those reported for this area <br />during the past seventeen years. Visual inspection of the area in 2015 revealed no evidence <br />of settling or slumping of the rock dump material and the drainage channels are functioning <br />as designed. The drainage on the west side of the upper part of the Indian Rock Dump, just <br />above the sericite stockpile, where the rock dump intersects native ground, had undergone <br />minor erosion. In 2012, a low gradient diversion ditch, oriented roughly perpendicular to the <br />main channel, was excavated allowing water from the channel to be diverted and dispersed <br />at lower velocities. Boulders were placed above the steep section of the channel and rip -rap <br />was placed below the boulders. The boulders and rip -rap function as energy dissipaters <br />such that flow velocities are reduced and sediment retention is enhanced. Observations in <br />2015 indicate that this repair appears to have corrected the erosion issue. The area will be <br />visually inspected after snow melt and heavy precipitation events. <br />"10780 - 10650" Level <br />Site Description: Identical to that of past reports for 1996 through 2014. <br />2015 Observations: The 2015 observations are similar to past observations. Visual <br />inspection of the area revealed no evidence of settling or slumping of the rock dump material. <br />The drainage channels are functioning as designed. <br />b) "10650 - 10600" Level <br />Site Description: Identical to that of past reports for 1996 through 2014 <br />2015 Observations: In 2015 the water elevation in this piezometer rose by approximately <br />7.6 feet between January and June, and then fell back to its normal range by the end of <br />August. This was very similar to previous years. Between June and July the water level in <br />IC10630 dropped 3.5 feet and continued to fall to its normal range in early fall. <br />As noted in previous reports, in October 2001 an obstruction was removed from Piezometer <br />IC10600, allowing it to be used for the collection of water level data. Between 2007 and <br />2011, the water level increased between 6.5 to 12.5 feet in May/June which is indicative of <br />heavier snow pack and increased summer rainfall. The water level usually drops back to its <br />normal range by the end of summer. By comparison, in 2012 and 2013, the water level <br />increased by 1.4 and 3.2 feet, respectively, and then fell back to its normal level by the end <br />of summer. <br />In 2015, the water level in IC10600 increased in elevation by 8.75 feet between January and <br />May compared to a rise of 11.8 feet in 2014. The rise in the phreatic surface in this <br />Homestake Pitch Reclamation Project <br />2015 Annual Geotechnical Report <br />M-1977-004HR <br />Page 2 <br />January 9, 2016 <br />2015 AnnualGeotechnicalReportText_Final.doc <br />