2006-04-19_REPORT - M1977004 - Laserfiche WebLink

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Pitch Reclamation Project April 14, 2006 2005 Annual Reclamation Report Page 14 . 4.4 Sediment Control Embankment The safety and efficiency of the sediment embankment is monitored with a network of surface and subsurface systems. There are five (5) permanent survey monuments where any physical movement of the embankment can be measured and nine (9) piezometers have been installed to monitor the phreatic surface within the embankment. Five of the piezometers were installed during the initial construction in 1980, and four of the piezometers were completed in the core of the embankment in 2001. The 2005 monument survey was performed on October 23 and results indicate the amount of vertical movement is minimal and within the range of survey error. No significant vertical displacement has occurred since the initial settlement following construction. Due to a very heavy snow melt in the spring of 2005, water levels reached an elevation of 9893.5 ft. am~sl (6.5 ft below the spillway) and maintained an average elevation of about 9884.5 ft. amsl during they second half of the year. Although the impoundment retained higher water levels during 2005, thei sediment control embankment continued to perform within the intent of its design. Seepage that was observed on the downstream face of the embankment in June 2000 has not reappeared following repair work conducted in 2001. The monuments and piezometers will continue to be monitored in 2006. A Sediment Embankment Report is submitted annually to the Colorado Division of Water Resources (CDW R) providing the results of the embankment-monitoring program. The 2005 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 2005, except when winter conditions prohibited access, in accordance with the recommended monitoring program. Inspection results indicate stable conditions for the Indian Creek and Tie Camp Creek waste rock dumps. Seven (7) piezometers were measured monthly to monitor seasonal phreatic surface fluctuations for both the Indian Creek and Tie Camp waste rock dumps. The piezometer measurement results indicate normal seasonal fluctuations in the depths to water similar to those observed in past years. Following the dry conditions of 2001 through 2003, the seasonal fluctuations observed during 2005 were more in line with historical variations. There continues to be no indication of instability due to the phreatic levels in the waste rock dumps. More detailed discussions and figures are presented in the December 2005 Annual Geotechnical Report on file with the DMG. 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 conducted in 2005 included 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 conducted 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) fori2005. Monitoring forthe CDPS was conducted at the designated POC SW-33, shown on Figure 3. Analytical tests conducted for the DMRs of SW-33 included, 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) analyses as required by the CDPS. During 2005, all analytical results were below the CDPS permit's 30-day