2016-08-01_REVISION - M1988112

• Permit No: M1988112
• IBM Index Class Name: Revision
• Doc Date: 8/1/2016
• Doc Name: San Luis Project Tailing Dam
• From: Battle Mountain Resources
• To: DRMS
• Type & Sequence: TR33
• Email Name: WHE
• Media Type: D
• Archive: No

July 6, 2016 Miller Geotechnical Consultants, Inc.
1027 W. Horsetooth Rd, Suite 200
Fort Collins, CO 80526
[phone] (office)
[phone] (mobile)
[e-mail]
Battle Mountain Resources, Inc.
PO Box 310
San Luis, CO 81152-0310
Attn: Mr. Julio Madrid, Site Manager
Re: 2016 Dam Safety Inspection Report for San Luis Tailings Dam
Dear Mr. Madrid:
Attached is the 2016 Annual Inspection Report for San Luis Tailings Dam. This is the third annual dam
safety inspection conducted by Miller Geotechnical Consultants (MGC) for the facility following the
initial (2013) detailed inspections and dam safety analyses of the facility performed by MGC which are
documented in the initial Detailed Inspection Report(MGC 20141).
The subsequent first annual inspection was performed in April 2014. Two maintenance issues were noted
in the April 2014 annual inspection: (1) minor surface erosion was observed in an area repaired in 2013
on the downstream right groin of the dam embankment, and(2)re-blocking of the sub-drain pipe outfalls
at the toe of the dam due to sloughing of earth materials above the pipes. The pipe outfalls were cleared
of debris in 2013 but new sloughing had partially re-covered the pipes in the spring of 2014. After the
April 2014 annual inspection, the right groin area was repaired again by re-grading and construction of
contour berms and ditches on the dam face directing runoff into the right groin ditch.
The second annual inspection was completed in January 2015. At that time, the right groin area repair
appeared to be in good condition, but minor erosion rills were observed. Additional erosion protection
was recommended to prevent gullying and erosion in this area. In 2015 the erosion-control measures were
enhanced by adding riprap-lined down-drain channels, and seeding with vegetation (see Photos 16-21,
attached). The system appears to be working quite well, except for some erosion where flow from the
rock-lined down-drains is jumping over the contour berms at the bottom of the rock channels(see Photos
19 and 20). This situation should continue to be monitored and may be improved by minor grading efforts
and shaping ofthe down-drain channels to reduce flow velocities into the cross berms. Vegetation appears
to be getting established and the erosional stability in this area is anticipated to improve over time as
vegetation matures.
1 MGC(2014). San Luis Project Tailing Dam Detailed Inspection Report, prepared for Battle Mountain Resources Inc. by
Miller Geotechnical Consultants,Fort Collins,CO,February.
1
2016 Dam Safety Inspection Report San Luis Tailings Dam