Hydrogeological Characterization and Feasbility-Level Dewatering Predictions

Client: NioCorp Developments Ltd.  |  Dates: 2014 -  Present  |  Site: Niobium Project | Elk Creek, Nebraska
 
Key Issues:
  • Faulted Carbonatite
  • Deep Underground Stopes
  • Brackish Groundwater
 
Scope:
  • Hydrogeological Characterization
  • Feasibility-Level Dewatering Predictions
  • Permit Support
Project Description:
 
The hydrogeologic study of the Elk Creek ore deposit was conducted for the purpose of characterizing the groundwater system in support of a Feasibility Study. Prior to the 2014 drilling campaign, there were no documented data concerning the groundwater system within or above the ore deposit. Historically, local water use for irrigation and consumption has been sourced from a shallow groundwater system hosted by a relatively thin glacial till unit. The primary objective of the hydrogeologic program was to ultimately predict groundwater inflows to the proposed underground mine workings over the life of the mine. However, a significant amount of characterization was necessary to develop a conceptual model in support of the predictive work.

Characterization of the hydrogeology of the Elk Creek Niobium Deposit was based on several phases of data collection, data analysis, and the development of a conceptual model of the groundwater system over a period of 13 months. The initial field work was conducted over a 6-month period in 2014 in conjunction with the exploration drilling program, and was therefore confined to diamond drill holes into the carbonatite in the immediate vicinity of the niobium deposit and proposed mine workings. Most of the testing was completed between depths of 200 and 850 m. A second phase of field work in 2015 included installation of two additional piezometers into the carbonatite outside of the deposit and installation of an 850-m deep, 6-in diameter test well. A 30-day, high-flow injection test was conducted to greatly improve the hydrogeologic understanding in support of the FS, permitting and mine planning.

 

SRK North America