INSPEC39428

• Permit No: M1977493
• IBM Index Class Name: Inspection
• Doc Date: 9/9/1999
• Doc Name: Insp Rpt
• From: DMG
• To: Climax Molybdenum Company
• Inspection Date: 8/30/1999
• Media Type: D
• Archive: No

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MINE ID # OR PROSPECTING ID # M-77-493
INSPECTION DATE 8/30/99 INSPECTOR'S INITIALS ACS
A monitoring inspection of the Climax Mine was conducted. The following list describes the locations
and facilities that were inspected and details the observations and recommendations that were made and
the discussions that were held.
Building and facility demolition in the mine/mill complex area was observed. The precon thickener tank
has been removed. The concrete base of the thickener and the center pivot structure remain in place.
The Operator reports that the tank was removed using cutting torches and a track hoe with a grappling
attachment. Steel salvage operations in the mill yard were observed. A track hoe with a nipper
attachment is used to cut salvaged steel to lengths acceptable to the salvage yard. The nipper
attachment is capable of cutting virtually any type of steel that may be encountered including large
I-beams. Discussion was held regarding unit costs used to estimate structural demolition costs and
establish the reclamation band requirements. Standard estimating strategy for demolition work would
be to define a crew to be employed for the job both in terms of labor and equipment and define the
hourly cost of each unit of labor and equipment. The next step is to determine an hourly rate of
production for the crew. Ideally, the crews and sates of production that have been in use for
structural demolition at the Climax Mine over the past several years can be used to estimate the amount
of demolition liability remaining and to set an adequate bond amount. The unit costs developed from
site-specific experience at Climax may then be reconciled with the unit costs published in the cost
estimating literature.
The Highway 91 frontage reclamation area was inspected. The reclamation history of this area is
documented in the annual reclamation reports provided by the Operator. In summary most of the grading
work was completed in 1994 and 1997, topsoil salvage from the bottom of the old Oxide Pond (Eagle Park
Reservoir) was applied in 1997 and the slopes were seeded and hydromulched. Spruce trees have been
planted at the toe of certain slopes down to the highway. All areas inspected are exhibiting good
establishment of herbaceous vegetation with the exceptions discussed here. Summer 1999 has been
characterized by frequent heavy rain. A particularly intense storm occurred at the Climax Mine on the
night of 6/27/99, two days prior to this inspection. As a result of the heavy rains, a number of
erosion gullies up to several feet deep have developed in the reclaimed Highway 91 frontage slopes. The
following treatments were discussed for repairing the gullies and to minimize future gully development.
• The small rills may be treated by installation of hay bales, check dams, or wattles spaced along
the length of the channel to promote siltation and self-healing.
• Larger gully repair will require backfilling, topsoil replacement, and revegetation. Based on
observations made during this inspection, it appears that a very small total volume of topsoil was
been washed off the slopes. The material that has been washed out of the erosion gullies is trapped
at the toe of the slope and may be salvaged. Commercially available erosion control products such
as jute mats may be useful in some of the gully repair locations.
• The primary erosion prevention consideration should be diversion of storm water an snowmelt around
reclaimed slopes by the installation of ditches and berms. However, it was observed during this
inspection that Climax had installed storm water controls at the crest of the slopes but intense
rainfall had generated enough runoff below the control structures to create rills and gullies. In
cases where upland diversion is insufficient to prevent gullying, Climax may consider installing
armored channels down the reclaimed slopes and directing concentrated runoff to these channels. The
channels could be stabilized by various treatments, including riprap and erosion control blankets.
Vegetation on one section of Highway 91 frontage has been killed by the development of a low pH seep
line. A possible corrective treatment discussed for this location was to carry the seep in a drain
buried in the slope to an outlet at the toe and route the water to the Climax water treatment system.
The drain would be covered, and the affected area revegetated. Climax should consult with the Division
as the design for the corrected treatment is developed and prior to installation.
Two different areas of the mine site where biosolids are in use as an organic soil amendment where
inspected. Biosolids applications to the Mayflower tailing surface were approved via technical
revision TR-02 and have been on going since 1990. The treated area is showing establishment of grass
with good diversity, virtually no weeds, and also shows invasion by native plant species. Application
of biosolids on the capped Robinson tailings was approved by technical revision TR-09 in 1995. The
area inspected is located just west of the Highway 91 underpass, below Buffehr's Lake. This area had
biosolids applied at 30 dry tons per acre and was seeded in October 1997 and October 1998. The 1997