2011-08-08_REVISION - M1977493 ‎(33)‎

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

•
Technical Revision (TR -18) Climax Molybdenum Company
Environmental Protection Plan Permit No. M -1977 -493
boundary of the Climax site. It is not considered an EPF nor is it ever to be used as an EPF or for
secondary containment by Climax. The Climax EPFs in place in the upper Eagle River watershed are in
fact designed and operated to preclude discharge of impacted water from mine facilities to Eagle Park
Reservoir.
Robinson Lake is an EPF and functions as the primary process water storage facility in the system. The
reservoir stores process water that is collected from the Tenmile and Mayflower TSFs and delivered
through the Tenmile Tunnel. Water collected from the Tenmile TSF is decanted through the Tenmile
Decant to the Tenmile Tunnel and water collected from the Mayflower TSF is pumped by the Mayflower
barge system (during Phase II Deposition) to the Tenmile Tunnel. Robinson Lake also collects seepwater
and toe drain discharge from 1 Dam as well as seepwater pumped from the Robinson Dam and 4 Dam
seepage collection systems. The reservoir primarily contains industrial process water, TSF seepwater
and 4 Dam seepwater, along with unintercepted storm water from the surrounding area and overflow from
Chalk Mountain Reservoir.
The Robinson TSF is an EPF and was originally constructed in 1936 straddling the uppermost
watersheds of Tenmile Creek to the north - northeast and the Eagle River to the west - southwest (Figure
AM- 06- T -01). The largest dam, the 240 foot high 1 Dam, contains the TSF upstream of Robinson Lake in
the Eagle River drainage. 2 Dam is partially inundated by the upstream portion of the Tenmile TSF in the
Tenmile Creek drainage. While the tailing material contained within the Robinson TSF consists primarily
of quartz silica and orthoclase feldspar, it also contains enough sulfur to be acknowledged by Climax as
acid producing.
In addition to tailing material, seepage from the Robinson TSF and water discharging from the toe drain
system beneath 1 Dam are potential sources of contamination. Tim's Pond and Warren's Pump Station
serves as the primary collection system for seepwater from 1 Dam and the Tenmile Tunnel and returns
collected water to the SDP via the 2 Dam Pipeline. Robinson Lake acts as a secondary collection system
for these co- mingled waters, and the Robinson Lake Pump Station will serve to return this water to the
industrial process water circuit for reuse as needed.
There are no designated chemicals stored or utilized in the Eagle River watershed.
T - 5.2.2 Environmental Protection Facilities
The following controls are designated EPFs to prevent potential impacts to Eagle Park Reservoir and the
East Fork of Eagle Creek from Climax operations:
• Robinson TSF and 1 Dam;
■ Robinson Lake and Dam;
• Warren's Pump System;
■ Robinson Lake Seepage Pump System;
■ 4 Dam Seepage Collection and Pump System;
■ Chalk Mountain Interceptor; and
• Robinson Lake Pumping System.
Climax EPFs in the upper Eagle River Watershed are described in detail below. Where appropriate, the
descriptions include the rationale for each EPF, the level of protection afforded Eagle Park Reservoir and
East Fork Eagle River, and the contingencies for worst -case storm or other events to preclude discharge
of impacted water.
Robinson TSF and 1 Dam: 1 Dam, along with 2 Dam, contain tailing material and an approximate 60
acre water pool within the Robinson TSF. The Robinson TSF is also discussed in the Tenmile Creek
watershed section. 1 Dam forms the divide between the Tenmile Creek and Eagle River basins.
1 Dam was upgraded and reconfigured in a project that was initiated in 1989 and completed in 1992.
EPP: Revision R1
T -17 July 2011