2004-05-03_REPORT - M1977004

• Permit No: M1977004
• IBM Index Class Name: Report
• Doc Date: 5/3/2004
• Doc Name: Annual Report and Fee
• From: Homestake Mining Company
• To: DMG
• Permit Index Doc Type: Annual Fee / Report
• Media Type: D
• Archive: No

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20U3 Annual Reciamau;:n R~q ~:;~ Page t4
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. During the summer and fall of 2000, an investigation was conducted
to determine the nature and extent of seepage on the downstream face of the Sediment Control
Embankment. The cause was determined to be perched water within the core of the
embankment. Homestake conducted repair work during the summer and fall of 2001.
The 2003 monument survey results indicate the amount of vertical movement is minimal and
within the range of suvey error. No significant vertical displacement has occurred since the
initial settlement following construction. Mondoring of the piezometers m 2003 Indicates an
overall lowering of the phreatic surface m the core of the embankment and Ihat the repair work
carried out in 2001 has been successful in reducing seepage through the core of the
embankment. The monuments and piezometers will continue to be monitored in 2004. No
seepage was observed on the downstream face of the embankment during 2003 and the
embankment continues to perform within the intent of its design.
A Sediment Embankment Report is submitted annually to the Colorado Division of Water
Resources (CDWR) providing the results of the embankment-monitoring program. This report is
provided in electronic Adobe Acrobat? Portable Document Format on the CD attached to this
report.
4.5 Waste Rock Dumps
Seven (7) piezometers were measured monthly to mondor seasonal phreatic surface Ilucluations
for the Indian Creek and Tie Camp waste rock dumps. Results were presented in the 2003
Geotechnical Monitoring Report submitted to the Division of Minerals and Geology (DMG) in
December 2003. Visual Inspections of the waste rock dumps in 2003 continued to indicate
stable conditions in both the Tie Camp and Indian Creek waste rock dumps. In 2003. the
piezometers continue fo show normal seasonal variations in the depths to water and, therefore,
the saturated zone and the base of the waste rock dumps. It also reflected a correction back to
more historic water levels following a very dry 2002. More detailed discussions and figures are
presented in the December 2003 report as provided in electronic Adobe Acrobati~~ Portable
Document Format on the CD attached to this sport.
4.6 Water Quality Monitoring
As cutlined in TR4. Homestake has monitored water quality since 1994 to verify the ntenifad
effectiveness of installation of the Pinnacle Adit plug. Water quality monitoring conducted in
2003 Included sampling points located at the North Pit Lake discharge (Sample Point NPL), the
Tie Gamp Creek drainage (Sample Points TCCDRN and TCC), the site discharge POC (Sample
Point SW-33), as well as sprang and seep surveys conducted in the sprang and fall.