2012-12-20_REPORT - M1977004 - Laserfiche WebLink

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Homestake Pitch Reclamation Project 2012 Geotechnical Observations Indian Creek and Tie Camp Creek Waste Rock Dumps 1. Indian Creek Waste Rock Dump a) "10800" Level Site Description: Identical to that of past reports for 1996 through 2012. 2012 Observations: The 2012 observations are similar to those reported for this area during the past sixteen years. Visual inspection of the area revealed no evidence of settling or slumping of the rock dump material in 2012 and the drainage channels are . functioning as designed. The drainage on the west side of the upper part of the Indian Creek (IC) Dump, just above the sericite stockpile, where the dump intersects native ground, had undergone minor erosion. In 2012, a low gradient diversion ditch, oriented roughly perpendicular to the main channel, was excavated allowing water from the channel to be diverted and dispersed at low velocities using boulders placed above the steep section of the channel and rip -wrap below the boulders. b) "10780 - 10650" Level Site Description: Identical to that of past reports for 1996 through 2011. 2012 Observations: The 2012 observations are similar to past observations. Visual inspection of the area revealed no evidence of settling or slumping of the dump material. The drainage channels are functioning as designed. c) "10650 - 10600" Level Site Description: Identical to that of past reports for 1996 through 201. 2012 Observations: Unlike 2011 when the water in Piezometer IC10630 rose by 3.2 feet in September and October following late summer rain events, in 2012 the water elevation in this piezometer rose by approximately 0.2 feet. This piezometer rarely has shown more than a foot of water rise following snow melt and it normally dries up by mid - summer. As noted in previous reports, in October 2001 an obstruction was removed from Piezometer IC10600, allowing it to be used for the collection of water level data. Between 2007 and 2011, the water level increased between 6.5 feet to 12.5 feet in May /June as a result of a very heavy snow melt. The water level then dropped back to its normal range by the end of summer. By comparison, in 2012 the water level increased by 1.4 feet. This condition is similar to other piezometers in the Indian Creek dump, and reflects the reduced snow pack in the area. d) "10725 - 10525" Level Site Description: Identical to that of past reports for 1996 through 2011. The minor overlap between this level and other bench designations reflects the original bench configuration. The total dump thickness in IC10525 is approximately 229 feet at this location.