NI43-101Pre-Feasibility Study Report - page 485

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
2.5:1V upstream slopes.
Dry stack tailings:
Maximum height of approximately 130 feet above existing grade;
Ultimate side slopes of 5H:1V;
Operational side slopes of 3.5H:1V.
Underdrain, liner and contact water management systems:
Underdrain system to manage and convey groundwater seeps and springs.
Composite liner system consisting from bottom to top:
12-inch thick low-permeability soil liner;
80-mil HDPE smooth geomembrane.
Seepage collection and contact water system management:
Toe drain at the base and northern end of the TSF;
Adjacent collection and evaporation ponds with ability to reclaim excess
water for use as make-up water at the Hydromet Plant or for dust control of
exposed tailings. Water Management
Surface water runoff from the undisturbed area west of the proposed TSF will be
collected and diverted around the TSF and returned to Coyote Creek. The diversion
ditch will be staged to match the expansion of the TSF. Temporary diversion ditches
will be constructed above working areas not yet protected by the permanent
perimeter diversion structures. Precipitation falling on the active surface of the TSF or
within the lined footprint of the TSF will be conveyed to the collection pond where it
will be allowed to evaporate or pumped back as reclaim water to the Hydromet plant,
if necessary, or used for dust control of exposed tailings. Surface water diversion
structures were designed for the Ultimate TSF Footprint and found also suitable for
the current 45-year LOM footprint. The temporary and intermediate diversion
structures noted in the drawings were modified as needed to optimize surface water
runoff from undisturbed areas during operations relative to the 45-Year LOM phased
construction and final footprint.
Perimeter surface water diversion channels will collect non-impacted runoff from
areas up-gradient of the ultimate footprint of the proposed TSF and convey them
around the TSF to Coyote Creek. The surface-water diversion channels will convey
runoff to the north and south along the western side of the ultimate tailings footprint.
The northern diversion channel will convey excess water from the existing stock pond
north and then east along the TSF embankment to Coyote Creek. The southern
diversion channel will collect runoff from areas south of the stock pond and convey it
south and then east to Coyote Creek. To facilitate construction, the diversion
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