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
2.0 SITE DESCRIPTION
2.1 General Setting
The Climax Molybdenum Mine is located primarily within the Tenmile Mining District, extending
into Summit, Lake, Eagle and Park Counties of Colorado. The mine site includes an open pit
mine, underground mine workings, mill /crusher facilities, associated tailings impoundments, and
water control facilities. The terrain at the site is mountainous with elevations ranging from
approximately 10,800 feet above mean sea level (msl) in the vicinity of the mine to more than
14,000 feet msl on nearby mountain peaks. Weather conditions can be severe at the mine, with
temperatures ranging from -20 °F to mid -70 °F and an annual average snowfall of 272 inches.
Average annual precipitation is 23 inches, about 80 to 90 percent falls as snow.
Within the site there are three primary watersheds: the Arkansas River Valley, Eagle River
Valley, and Tenmile Creek Valley. The mine and mill are located on the Continental Divide
between Tenmile Creek and the East Fork of the Arkansas River, with the tailing impoundments
located in the Tenmile Creek Valley and the Eagle River Valley (Figure 1).
Climax utilizes one groundwater well within the Tenmile Watershed for industrial use; the
McNulty Well is used, together with surface water sources, as makeup water for lime slaking
and feed to a small potable water treatment system at the Sludge Densification Plant.
Raw water for industrial uses in the mill and treatment for potable water is delivered from the
Arkansas Pond, the pond created by former gravel quarry operations in the upper Arkansas
River Watershed. Although this location is identified as the Arkansas Well, it is essentially a
surface water intake into a wet well. A submersible pump installed in the wet well delivers water
to a clear well at the water treatment building in the mill area. Raw water is delivered directly
from the clear well to the raw water storage tank, and a portion of the water is directed to a
small potable water treatment plant.
2.2 Site Hydrogeology
Climax Mine is located in the Mosquito - Tenmile Range of the southern Rocky Mountain
Cordillera. The ore body is hosted by two Precambrian rock formations, the Idaho Springs
Formation, and the Silver Plume Granite. The Idaho Springs Formation is a meta - sedimentary
rock, metamorphosed 1.7 billion years ago during a period of major geologic activity. Its major
components are biotite schist and gneiss. Silver Plume Granite occurs in stocks, dikes and sills
that intruded the Idaho Springs Formation approximately 1.4 billion years ago. These two
formations also are intruded, to a lesser degree, by early Tertiary diorite porphyry and quartz
monzonite approximately 60 million years old.
The Climax ore body lies just east of the Mosquito Fault, an important local structure that trends
roughly north- south, and that dips approximately 60 degrees to the west. The fault, as shown on
Figure 1, runs north- northeastward across the Tenmile Creek valley over a distance of
approximately 30 miles. The Mosquito Fault presents a discontinuity between the Precambrian
bedrock on the east with the Paleozoic and Tertiary bedrock on the west.
Groundwater in the vicinity of the Climax Mine site is generally present within a thin veneer of
alluvium and glacial till overlaying the bedrock, and ranges from near ground surface to a few
tens of feet below ground surface. Groundwater occurrence within the bedrock is limited to the
upper fractured portion of the bedrock units. A hydrogeologic study of the underground workings
EPP — Appendix C
August, 2011 2