2016-01-20_REPORT - M1977004HR

• Permit No: M1977004
• IBM Index Class Name: REPORT
• Doc Date: 1/20/2016
• Doc Name: Annual Geotechnical Report
• From: Homestake Mining
• To: DRMS
• Annual Report Year: 2015
• Email Name: DMC
• Media Type: D
• Archive: No

Colorado Department of Natural Resources
Division of Reclamation, Mining and Safety
Attention: Mineral Division
1313 Sherman Street, Room 215
Denver, CO 80203
INIID
.SAM 0Z016
MOON OFRECUMATIOM
HIMOSAFETY January 9, 2015
RE: HOMESTAKE PITCH RECLAMATION PROJECT
2015 ANNUAL GEOTECHNICAL REPORT (M-1977-004HR)
Dear Division;
Attached you will find the 2015 Geotechnical Report for the rock mamgement areas at the Homestake
Pitch Reclamation Project. These include the Indian and the Tie Car tp Rock Dumps. The history of the
rock dumps (rock dumps) has been provided in previous annual r --ports and is not repeated in this
report. The rock dumps were inspected monthly in 2015, except when winter conditions prohibited
access, in accordance with the recommended monitoring program. A site location map and rock dump
piezometer map are provided as Figures 1 and 2, respectively. Detailed analysis and presentation of the
2015 data from all piezometers are provided in the following pages.
The inspections conducted in 2015 indicate stable conditions for the Indian and Tie Camp Rock Dumps.
Reclamation repairs done in 2012 had alleviated drainage and erosion issues. The dumps were re -seeded
in 2014. We will continue close inspections of the rock dumps in 2016.
The water level readings in 2015 are plotted on Figure 3 and a graph with piezometer water levels since
1996 is provided as Figure 4. The Y-axis on these plots is labeled as depth to water from the ground
surface. Two of the piezometers in the Indian Rock Dump were replaced in 2011 after several years of
issues associated with corrosion and silt buildup in the well casing made it difficult to get an accurate
reading of the phreatic surface in the rock dump. All of the piezometers are now functioning as required
to provide accurate water level information. The 2015 monthly water level measurements are provided
on Table 1 of the attached report. The piezometer readings in 2015 were indicative of a moderate snow
pack when compared with the 2012 and 2013, but below the snow pack and total annual precipitation in
2014. As measured in the site's precipitation gage from October through the following September, during
2015 period the site received 25 inches of precipitation, compared with 32 inches during the same period
in 2014. As reflected on Figure 4, the water levels in rock dump piezometers show little fluctuation in the
winter months with a temporary rise in response to the spring snow melt or summer rain events. They
usually return to normal levels in mid to late summer. Please feel free to contact me in the Salt Lake City
Utah office [phone] or via cell phone at [phone] if you have any questions.
Bill Ferdinand
Director of Environment
cc: Dale Davis - Homestake Mining Company -Sargents
Phillip DeDycker - ARCADIS, Inc.
Homestake Mining Company of California ❖ 460 West 50 North, Suite 500,
Salt Lake City, Utah 84101
Tele [phone] ❖ Mobile: [phone]