2011-04-19_REPORT - M1977004 - Laserfiche WebLink

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2010 and required flushing in August. The silt problem in IC10300 is persistent and became a problem again in November, resulting in some of the 2010 readings being unreliable. 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. We will continue to evaluate the cause and possible effects of the seasonal spikes in the water levels in some piezometers, and observe surface features of the dumps. However, there continues to be no indication of instability in either of the waste rock dumps. In 2011, we plan to pressure wash the problem piezometers again to remove the silt built up in the piezometers over the past 20 years. If this continues to be a problem we will evaluate replacement of the piezometers. More detailed discussions and figures are presented in the 2010 Annual Geotechnical Report filed with the Division in December 2010. 4.6 Water Quality Monitoring As outlined in TR4, Homestake has monitored water quality since 1994 to verify the intended effectiveness of installation of the Pinnacle Adit plug. Water quality monitoring was conducted in 2010 including sampling points located at the North Pit Lake discharge (Sample Point NPL), the Tie Camp Creek drainage (Sample Points TCCDRN and TCC), the site discharge POC (Sample Point SW-33), as well as spring and seep surveys performed in the spring and fall. Monthly discharge- monitoring reports (DMRs), pursuant to Colorado Discharge Permit System (CDPS) number CO-0022756, were submitted to the Colorado Department of Public Health and Environment (CDPHE) for 2010. Monitoring for the CDPS was conducted at the designated POC SW 33, shown on Figure 3. Analytical tests conducted for the DMRs at SW 33 as required by the CDPS include: flow; dissolved radium 226; total radium 226/228; total uranium; pH; total suspended solids (TSS); total dissolved solids; oil and grease (visual only); potentially dissolved zinc; and whole effluent toxicity (WET). During 2008, all analytical results were below the CDPS permit's 30- day average or daily maximum limitations and WET testing results were within permit limits. The 2010 DMRs are on file with the CDPHE-Water Quality Control Division. Pitch Reclamation Project Colorado Mined Land Reclamation Board 2010 Annual Reclamation Report 25