Rare Element Resources
Bear Lodge Project
Canadian NI 43-101 Technical Report
October 9
th
, 2014
10135-200-46 - Rev. 0
18-25
Office may also provide oversight regarding dam safety, surface water diversion, and
water rights issues related to the TSF site.
18.2.7.1.2Engineering Criteria
There are no prescriptive criteria presented in the Non-coal Rules and Regulations for
mine waste management. However, it is stated in Chapter 3 of the regulations that
“tailings impoundments, tailings disposal area shall be designed, constructed, and
operated in accordance with established engineering principles using best technology
currently available to ensure long term stability and to prevent contamination of
surface or groundwater” (WDEQ 2006). This guideline served as the primary basis for
developing the design criteria for the TSF pre-feasibility level design.
The tailings produced by the rare earth element processing plant will be a non-
hazardous waste based on current test data and deduced geochemical
characteristics of the waste stream. The tailings solids will be non-acid generating
material; however, the residual moisture in the tailings may be slightly acidic because
of the rare element extraction process. Lime stone and quick lime will be added to the
tailings to neutralize the material prior to transport to the TSF. In addition, the tailings
delivered to the TSF will be dewatered to semi-dry, soil-like material suitable for truck
hauling and deposition using conventional earthwork equipment. Based on these
waste characteristics and the TSF design guidelines referenced above, the following
criteria were set for the pre-feasibility-level design study for the TSF.
•
“Zero discharge” facility with respect to contact surface water management
and any precipitation infiltration (i.e., seepage) emanating from the tailings
stack at or above the base of the lined TSF;
•
Non–contact surface water runoff diverted around the facility and into the
current receiving stream;
•
Composite liner system consisting of minimum 12-inch compacted low
permeability soil liner exhibiting a hydraulic conductivity no greater than 1x10
-7
cm/sec overlain by 80-mil high-density polypropylene (HDPE) geomembrane
liner;
•
Staged construction to minimize exposure of unused portions of TSF and limit
active areas of disturbance;
•
Capture, control, and separation of flow from groundwater springs within the
TSF footprint by construction of an underdrain system to prevent impacts to
groundwater quality and to convey the spring flows beyond the TSF boundary
as non-contact or non-impacted waters;
•
Truck haul and controlled dump plan for waste disposal;
