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Homestake 2016 Geotechnical Observations <br />Pitch Reclamation Project Indian and Tie Camp Rock Dumps <br />"10725 - 1 0525" Level <br />Site Description: Identical to that of past reports for 1996 through 2015. The minor overlap <br />between this level and other bench designations reflects the original bench configuration. <br />The total dump thickness at Piezometer IC10525 is approximately 229 feet at this location. <br />2016 Observations: Piezometers IC10600 and IC10525 bound this area and like <br />Piezometer IC10600, the 2016 water level in Piezometer IC10525 rose by 7.9 fleet. This is <br />approximately 1.1 feet lower that the rise in the phreatic surface measured in 2015 and 2014. <br />In 2016, the water level in Piezometer IC10525 dropped back to its normal level by late <br />summer compared with some previous years where heavier rainfall during the summer <br />months prevented this piezometer from dropping completely to its January level. <br />"10600 - 10400" Level <br />Site Description: Identical to that of past reports for 1996 through 2015. <br />2016 Observations: Piezometer IC10440 represented this area of the rock dump until it <br />became non-functional in 1996. Piezometer IC10525 is also considered representative of this <br />area of the rock dump and was described in the previous section. <br />"10400 -10370" Level <br />Site Description: In 1997, the face of the permanent low-grade stockpile was reconstructed <br />on the Indian Rock Dump. The purpose of the slope reconstruction was to reduce the <br />potential for infiltration and promote more rapid runoff from the stockpile area. This <br />reconstruction appears to have effectively reduced seepage in this area. <br />2016 Observations: In 2011, replacement Piezometer IC1037OR was completed <br />approximately 67 feet west of the location of Piezometer IC10370. The piezometer was <br />terminated at 208 feet below ground surface (bgs) and completed with an 8 -inch steel <br />protective casing and set in concrete. Upon completion, a transducer was installed in <br />Piezometer IC1037OR to assist in monitoring water levels. In 2012, the water level elevation <br />in Piezometer IC10370R rose by 7,1 feet in the spring and fell back to an acceptable range <br />by late summer. In 2013, the water level rose by 10.9 feet during the spring snow melt and <br />lost approximately 5 feet of that gain by the end of the year. The increase in water level in <br />2013 compared with 2012 was attributable to heavier snow pack and higher summer <br />precipitation in 2013. The same trends were observed in 2014, when the water level in <br />Piezometer IC1037OR increased in elevation by 11.4 feet between January and June. In <br />2016, the phreatic surface rose 5.55 feet, which was like the 2015 observations. <br />Piezometer IC10360, is also located in this bench had a water level increase of 8.75 feet in <br />the spring_ This rise compared with a 6.52 and 7.68 feet rise in 2015 and 2014, respectively. <br />This condition is like that of the other piezometers in the Indian Rock Dump, and reflects the <br />seasonal snow pack in the area, <br />"10300 -10100" Level <br />Site Description: The Indian Rock Dump was regraded in 1994 following procedures <br />approved in the February 1994 Technical Revision, During 1995, several minor, localized <br />areas of slope instability were noted, corrected, and reported in the 1995 Annual <br />Geotechnical Report. <br />Homestake Pitch Reclamation Project Page 3 <br />2016 Annual Geotechnical Report December 31, 2016 <br />M-1977-004HR 2016 AnnualGeotechnicalReportText Flnal.doc <br />