2011-08-08_REVISION - M1977493 ‎(36)‎

• Permit No: M1977493
• IBM Index Class Name: REVISION
• Doc Date: 8/8/2011
• Doc Name: EPP- Water Quality Monitoring Plan.
• From: Climax Molybdenum
• To: DRMS
• Type & Sequence: TR18
• Media Type: D
• Archive: No

•
Water Quality Monitoring Plan Climax Molybdenum Company
Version: R1 Permit No. M -1977 -493
mg /L. Concentrations of the other primary constituents have remained relatively stable over the
monitoring period with some fluctuation related to seasonal changes in groundwater elevations.
3.2 Eagle River Watershed
As illustrated on Figure 1, the Eagle River Watershed is located in the western portion of the
Site below the crest of 1 Dam.
3.2.1 Existing and Potential Future Uses of Groundwater
Groundwater in the upper Eagle River Watershed within the Climax Mine property boundary
occurs primarily in the areas downstream of the former Robinson Tailings Storage Facility (TSF)
and Robinson Lake. Upstream of the Eagle Park Reservoir, significant and continuous
groundwater flow in the alluvium and bedrock throughout the valley is unlikely as groundwater
flow is intercepted by the reservoirs and the cut -off wall associated with the Robinson Lake
Seepage Collection system. Within these areas, current and future domestic or agricultural
development of groundwater would not be likely given the site location and climate conditions.
The current and future groundwater use at the site is limited to recharge of the Eagle River.
Monitoring at Climax's proposed internal monitoring locations will provide additional data to
further characterize groundwater conditions in the Upper Eagle River Watershed.
3.2.2 Location and Description of Classified Stream Segments
Eagle River basin, Segment 3, contains all tributaries to the Eagle River, including wetlands,
from the source to the compressor house bridge at Belden. Exceptions include; Segment 4 -
the mainstem of Homestake Creek from the confluence of the East Fork to the confluence with
the Eagle River as well as Segment 1 - all tributaries and wetlands to the Eagle River system
within the Gore Range - Eagle's Nest and Holy Cross Wilderness Area.
Segment 3 of the Eagle River basin is classified as Aquatic Life Cold 1, Recreation E, Water
Supply, and Agriculture.
3.2.3 Potential Contamination Sources
The Eagle River Watershed is bounded on the east by 1 Dam, the western embankment of the
former Robinson TSF and contains two fresh water reservoirs (Eagle Park and Chalk Mountain),
as well as Robinson Lake, which stores process water for use in the mill. Reclaimed process
water decanted from the TSFs is delivered to Robinson Lake via the Tenmile Tunnel.
As described more fully in the EPP, the sources of potential contamination in the upper
watershed of the East Fork of the Eagle River within the Climax property include:
• 4 Dam seepage;
■ Robinson Dam seepage
• Tenmile Tunnel and 1 Dam seepage;
■ Robinson Lake (aka: Robinson Reservoir); and
■ A portion of the Robinson TSF.
3.2.4 Hydrogeology
The groundwater in the upper Eagle River Watershed occurs primarily in the shallow alluvium
above the bedrock. Data from test pits (Kumar and Assoc., 1993) located north -west of
EPP — Appendix C
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