2016-12-12_PERMIT FILE - C1981019A ‎(2)‎

• Permit No: C1981019A
• IBM Index Class Name: Permit File
• Doc Date: 12/12/2016
• Doc Name: Permits
• Section_Exhibit Name: Volume 15 Rule 2
• Media Type: D
• Archive: Yes

RULE 2 PERMITS
each sample location represents an area of about 5.7 acres in size. A hand shovel is used to take small,
representative surface samples of spoil across the sample area.
Regraded Overburden Suspect Levels:
Parameter
Suspect Level
H
Less than 5 or greater than 9 standard units
Electrical Conductivity
Greater than 12 millimhos/cm
Sodium Absorption Ratio
Greater than 15
The laboratory results are kept at the mine site. Results of the sampling program are provided in the
appropriate Annual Reclamation Report and are periodically checked during CDRMS quarterly complete
inspections.
The mining sequence for the planned operation is shown on the Mine Plan Map (Map 2313). Cross
sections showing the post mining pit backfill are presented on the Pre -Mining and Post -Mining Cross
Sections (Map 20C). The temporary overburden stockpile location is presented on Map 23B. The map
depicting spoil grading is presented as Map 29B.
The spoil suitability and special handling procedures are described in detail in section 2.05.3(1) of the
Collom permit revision. The initial development of the stockpile is anticipated to begin during the year
2016 with the excavation of the initial box cuts and continue over the next five years of operation
dependent on production rates. Following this period, mine pit advancement will allow for placement of
mined spoil into the original box cut area.
The temporary spoil pile will be used to fill and recontour the final pit sequence in the final three years of
mining activities (See Map 29C — Temporary Spoil Pile Design). Out of pit stored spoils will be used in
the construction of the post mine topography. Approximately 168 million cubic yards of storage capacity
for the temporary spoil stockpile will be needed.
The toe of the fill will be placed at the bottom of the Little Collom Gulch Drainage and the stockpile will
eventually extend upward about 600 feet in thickness to an elevation of 7000. The stockpile will remain
in place until the last few years of mining and will have a life of about 17-22 years depending on
production rates. As such, the lower portions of the stockpile will be completed and stabilized before the
top is completed. To ensure that a phreatic water surface does not develop during the life of the stockpile,
a rock drain will be installed at the base of the fill along its entire length. The spoilpile will be confined
by the valley slopes on both sides. Volume 20, Exhibit 23, Item 1 and Item 2 provide the geotechnical
report for the temporary spoil pile.
The temporary overburden stockpile will be constructed in 50 to 100 foot lifts by use of trucks, dozers
and loaders. Each lift will be dumped at angle of repose. Maintenance techniques will consist of blading
of roads and ramps, along with the use of dust control during active times of operation. During
construction a dozer will be used develop and spread the end -dumps created by the trucks, this will be the
primary method used to build the temporary overburden stockpile. Sediment control will be implemented
to ensure adequate containment of potential runoff throughout the life of the operation. Chemical
stabilization and/or temporary seeding via the broadcast method may be employed during inactive times
of operations on the temporary stockpile to reduce the erosion potential utilizing the following seed mix:
Western wheatgrass @ 41bs PLS/Acre
Collom — Rule 2, Page 82 Revision Date: 11/16/16
Revision No.: MR -166