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Homestake <br />2012 Geotechnical Observations <br />Pitch Reclamation Project Indian Creek and Tie Camp Creek Waste Rock Dumps <br />2012 Observations: Piezometers IC10600 and IC10525 bound this area and similar to <br />piezometer IC10600, the 2012 water level in Piezometer IC10525 rose by 2.1 feet. This <br />compares with an 11.0 feet rise in 2011, 6.5 feet in 2010 and 8.6 feet in 2009. The small <br />rise in the water level in 2012 reflects directly on the reduced snow pack after several <br />years with heavier snow pack. Even with the greater rise in previous years, the water <br />level fell in Piezometer IC10525 by later summer to a normal operating range. <br />e) "10600 - 10400" Level <br />Site Description: Identical to that of past reports for 1996 through 2011. <br />2012 Observations: Piezometer IC10440 was located in this area of the rock dump; <br />however, it was lost in 1996. As such, Piezometer IC10525 is also considered <br />representative of this area of the rock dump and was described in the previous section. <br />f) <br />g) <br />"10400 - 10370" Level <br />Site Description: Identical to that of past reports for 1997 through 2011. During 1997, <br />Homestake reconstructed the face of the permanent low -grade stockpile located on the <br />Indian Creek Rock Dump. The purpose of the slope reconstruction was to reduce the <br />potential for infiltration and promote more rapid runoff from the slope. No seepage was <br />observed in this area in 2011 or 2012. <br />2012 Observations: In 2011 replacement Piezometer IC10370R was completed <br />approximately 67 feet to the west of the former location of IC10370. The piezometer was <br />terminated at 208 ft bgs and completed with concrete wellhead and 8 inch steel <br />protective casing and concrete apron. Upon completion, a transducer was installed in <br />Piezometer IC10370R to assist in the monitoring water levels. In 2012, the water level <br />elevation in Piezometer IC1037OR rose by 7.1 feet in the spring and fell back to an <br />acceptable range by late summer. Since late summer, the water level in IC 10370R has <br />fallen about 5.3ft. This decrease in water level is due to the effects of sustained low <br />precipitation levels for 2012 and the effectiveness of the replacement piezometers. <br />Piezometer IC10360 is also located in this area. Water levels in this piezometer <br />averaged about 227.8 feet bgs in 2012, with a seasonal fluctuation of 5.0 feet compared <br />to a rise of 11.1 feet in 2011. Despite a record snow pack in 2011 and heavy snow <br />packs from 2008 through 2010, the water level rise in IC10360 over the past five years is <br />below the levels recorded from 2002 through 2007. Since June of 2012, the water level <br />in IC 10360 has dropped by about 5.3ft, similar to IC 10370. The similarity between the <br />water levels in IC 10370 and IC 10360 further suggests that the decline in water levels in <br />these two piezometers, which are in relative close proximity to one another, reflect a <br />lowered ground water level in response to low precipitation levels for 2012. The total <br />depth of this piezometer is 260 feet and the thickness of the dump is approximately 240 <br />feet. <br />"10300 - 10100" Level <br />Site Description: The Indian Creek Rock Dump was re- graded in 1994 following <br />procedures approved in the February 1994 Technical Revision. During 1995, several <br />minor, localized areas of slope instability were noted, corrected, and reported in the <br />1995 Annual Geotechnical Report. <br />2012 Observations: Field observations indicate that the repairs performed in 1995 were <br />successful and no new areas of surficial instability (slips) were observed from 1996 <br />Homestake Pitch Reclamation Project Page 3 <br />2012 Annual Geotechnical Report December 19, 2012 <br />M- 1977 -004HR 2012AnnualGeotechnicalReportText _Final.doc <br />