NI43-101Pre-Feasibility Study Report - page 486

Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
, 2014
10135-200-46 - Rev. 0
channels will be a trapezoidal section with a 10-foot wide flat bottom and 3H:1V side
slopes. The portions of the diversion channels that flow north and east along the
footprint of the TSF have mild slopes and low velocities and channel revetment is not
required. The portions of the diversion channels that flow east along the TSF
embankment have steeper slopes and higher velocities and will require the use of
riprap or a similar revetment layer to reduce the potential for scour and erosion.
Surface water runoff from direct precipitation within the lined TSF will be conveyed to
the collection pond via the TSF toe drain system. Erosion control measures will be
placed along the dry stack tailings out slope and elsewhere as required to prevent the
erosion of the dry stack and TSF toe berm embankment material and reduce
sediment transport into the collection pond. Pond
The TSF pre-feasibility design layouts include the use of collection ponds to manage
contact water from the TSF in order to maintain a ‘zero discharge’ facility. The
collection pond system described below is based on conservative assumptions
including 100 percent runoff from the average monthly precipitation and reduced
evaporation efficiency in average monthly evaporation estimates. The proposed
system will be optimized during the feasibility design. The intent of this level of design
is to demonstrate the feasibility of incorporating such a system for contact water
management in place of treating contact waters prior to release from the property.
Pending the final water balance of the Hydromet plant operations, contact water may
be collected and returned to the plant for reuse to reduce fresh water demands,
instead of being routed to evaporation ponds for dissipation from the TSF. The
selection of a preferred contact-water management system in the TSF will be
determined as the project is advanced. Either system (collection and reuse, or
collection and evaporation) will allow operation of the TSF as a ‘zero discharge’
The collection pond(s) for the TSF will collect contact runoff water from the active
areas of the TSF. Contact water is defined as precipitation that drains from, or over,
un-reclaimed filtered tailings materials placed in the TSF. An initial pond will be
constructed with sufficient capacity and surface area to store and evaporate runoff
from the start-up facility, which will operate for about one year before operations
expand into a larger area. The pond will be expanded again in Year 3 as the TSF is
expanded and then in Year 7 to the final collection pond configuration required to
provide capacity for the 45-year LOM TSF. Should the TSF expand beyond the 45-
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