2010-04-19_REPORT - M1977004 - Laserfiche WebLink

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Pitch Reclamation Project Colorado Mined Land Reclamation Board 2009 Annual Reclamation Report Based upon the 2009 monitoring data and embankment inspections, it appears that the cutoff trench and clay blanket have addressed the previous localized perched zone and related seepage through the embankment core, thus allowing the embankment to function as designed. The monuments and piezometers will continue to be monitored in 2010. A Sediment Embankment Report is submitted annually to the Colorado Division of Water Resources (CDWR) providing the results of the embankment-monitoring program. The 2009 report is provided in electronic Adobe Acrobat© Portable Document Format on the CD attached to this report. 4.5 Waste Rock Dumps The waste rock disposal areas were inspected monthly during 2009, except when winter conditions prohibited access, in accordance with the recommended monitoring program. Six(5) of the seven (7) piezometers were measured monthly to monitor seasonal phreatic surface fluctuations for both the Indian Creek and Tie Camp waste rock dumps. During the winter of 2007, wildlife knocked off the casing of piezometer IC10370 and kicked debris into the 2 inch pipe. This piezometer had never shown seasonal water levels fluctuations greater than one foot, with the averaged water level of 190.7 feet bgs. The bottom of this piezometer is 192 feet bgs. In the fall of 2009, this piezometer was flushed with pressurized water to within three feet of its historical depth of 192 feet bgs. Now the total depth is approximately 189 feet bgs, with no water in the pipe. The flushing will allow use of piezometer 10370 as part of the ongoing Indian Creek monitoring program. Additionally in the fall of 2009, piezometer 10300 was also flushed with pressurized water in an attempt to wash out some of the silt built up in the casing. The 10300 piezometer washed out fairly well although it isn't as deep as it was historically, but the readings appear to be more in line with the historical reading in this piezometer. In the past, water levels in several of the piezometers have had seasonal fluctuations and generally fall back within an acceptable range by mid-summer. Following the dry conditions of 2001 through 2003, the seasonal variations have increased in recent years as heavier snow packs have occurred. We believe the increases in the maximum water levels are related to the spring snow melt and the saturated zones within the dump remain thin. In 2010, Homestake will continue to evaluate the cause and possible effects of the seasonal spikes in the water levels in some piezometers, and observe surface features 13