2007-12-17_REPORT - M1977004 - Laserfiche WebLink

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Homestake 2007 Geotechnical Observations Pitch Reclamation Project Indian Creek and Tie Camp Creek Waste Rock Dumps 2007 Observations: Piezometer IC10440 was located in this area; however, it was lost in September 1996. Piezometer IC10525 can also be considered to be within the area. The 2007 data for that piezometer is described above. d) "10400 - 10370" Level Site Description: Identical to that of past reports for 1996 through 2006. 2007 Observations: The 2007 field observations are similar to those reported in past reports. Piezometer IC10360 is located in this area. Water levels in this piezometer averaged about 224.3 feet bgs, with a seasonal fluctuation of approximately 11.8 feet. The maximum water level for 2007 returned to levels observed in previous years. The total depth of this piezometer is 260 feet and the thickness of the dump is approximately 240 feet. Piezometer IC10370-was monitored for~the"firsfYour months when wildlife knocked off the casing and kicked rock material into the 2 inch pipe. This piezometer has never shown seasonal water levels fluctuations greater than 1 foot with the averaged water level of 190.7 feet bgs. The bottom of this piezometer is 192 feet bgs. During 2008, an attempt will be made to remove the material in the piezometer, and if successful, monitoring will begin again by mid-year. During 1997, Homestake reconstructed the face of the permanent low-grade stockpile located on the Indian Creek Waste Rock Dump. The purpose of the slope reconstruction was to reduce the potential for infiltration and promote more rapid runoff from the slope. No seepage was observed in this area in 2007. e) "10300 - 10100" Level Site Description: The Indian Creek Waste Rock Dump was regraded in 1994 following procedures approved in the February 1994 Technical Revision. During 1995, several minor, localized areas of slope instability were noted, corrected, and reported in the 1995 Annual Geotechnical Report. 2007 Observations: Field observations indicate that the repairs performed in 1995 were successful and no new areas of surficial instability (slips) were observed from 1996 through 2006. Piezometer IC10300 is located in this area. In 2007, water levels in this piezometer averaged 188.5 feet bgs, with a maximum seasonal fluctuation of approximately 10.0 feet, consistent with maximum water level observed in preceding. years. 2. Tie Camp Waste Rock Dump a) "10400 - 10100" Level Site Description: The Tie Camp Waste Rock Dump was regraded in 1994 following procedures approved in the February 1994 Technical Revision. During 1995, minor, localized areas of slope instability were noted, corrected, and reported in the 1995 Annual Geotechnical Report. 2007 Observations: Field observations indicate that the repairs performed in 1995 were successful and no new areas of surficial instability were observed from 1996 through 2006. Piezometer TC10375 monitors the Tie Camp Creek Waste Rock Dump. In 2007, water levels averaged 170.8 feet bgs, with a maximum observed seasonal fluctuation of 5.1 feet in Homestake Pitch Reclamation Project Page 2 2007 Annual Geotechnical Report December 14, 2007 M-1977-004HR 2007ReportText_Final