2010-12-21_REPORT - M1977004

• Permit No: M1977004
• IBM Index Class Name: REPORT
• Doc Date: 12/21/2010
• Doc Name: 2010 annual geotechnical report
• From: Home Stake
• To: DRMS
• Email Name: RCO
• Media Type: D
• Archive: No

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HOMI `SWALIF E
Grants NM Office
December 20, 2010
Mr. Bob Oswald
Colorado Department of Natural Resources
Division of Minerals and Geology
691 CR 233, Suite A-2
Durango, CO 81301
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N 0 3 72010 Alan D. Cox
Manager - Pitch
RE: HOMESTAKE PITCH RECLAMATION PROJECT
2010 ANNUAL GEOTECHNICAL REPORT (M-1977-0041)
Dear Mr. Oswald:
Attached you will find the 2010 Geotechnical Report for the waste rock management areas at the
Homestake Pitch Reclamation Project. The history of the rock dumps has been provided in
previous annual reports and is not repeated in this discussion. The waste rock dumps were
inspected monthly in 2010, except when winter conditions prohibited access, in accordance with
the recommended monitoring program. A site map with piezometer locations is provided as
Figure 1. Detailed analysis and presentation of the 2010 data from all piezometers are provided in
the following pages.
The visual inspections conducted in 2010 indicate stable conditions for the Indian Creek and Tie
Camp waste rock dumps. As you recall, the project lost its site manager, Vern Kelso, to a snow
mobile accident in March of 2010. Vern s death was a tremendous loss to all, and set back the
monitoring program until a new site manager, Dale Davis, was hired in May. Dale had a steep
learning curve at the site, but by mid-year he understood the site conditions and was taking care of
the property. As a result of Vern's death, the water level measurements in the rock dump
piezometers were not documented until May. Historically, the water levels in the piezometers
show little fluctuations during the winter months.
Once again in 2010, a few of the piezometers became plugged with silt and required flushing with
high pressure water to get the probe down to the water. Each piezometer behaves differently and
their flushing requires experience to be successful. The water levels in the rock dump piezometers
in 2010 continued to show normal seasonal fluctuations when the silt was not an issue. The 2010
water level measurements are provided on Table 1 of the attached report. A chart showing the
2010 data is also provided as Figure 2 and a chart with piezometers water levels monitoring since
1996 provided as Figure 3. The Y-axis on these plots is labeled as depth to water from ground
surface. Note that prior to October 2001, data was not obtained from Piezometer IC10600 due to
the presence of a gravel obstruction that blocked the passage of the piezometer. Additionally, in
2007, the local elk herd destroyed the stand-pipe casing in Piezometer IC 10370 and consequently
caused the upper part of the borehole soil to collapse into the piezometer casing. This resulted in
approximately six feet of rock debris being introduced into the bottom of the piezometer,
rendering it non-functional until the fall of 2009 when the obstruction was cleared from the bottom
of the casing by high pressure flushing. This allowed us to remedy that problem and to begin using
the Piezometer IC10370 as part of the monitoring system with measurements taken the last three
months of the 2009 and eight months of 2010. Piezometer IC10300 was also flushed in 2009 to
Homestake Mining Company of California P.O. Box 98, Grants, NM 87020
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