The Evolution and Future of Overburden Dewatering at Highland Valley Copper
Highland Valley Copper has been mining its Valley pit since 1982. This pit requires large quantities of water-bearing overburden to be stripped away to expose the porphyry copper deposit underneath it. In order to dewater the aquifers, the mine began extracting groundwater in 1985 through the implementation of strategically placed deepwells containing submersible pump sets. Initially, dewatering focussed on aquifers close to the topographic surface and pumping flow rate targets were set in reaction to observed piezometric levels. It was recognized in recent years that in order to accomplish dewatering ahead of mine development, an accelerated level of activity would be necessary. To accomplish this as economically as possible, a more proactive approach to forecasting required flow rates - and, by extension, planning and budgeting - was required. At the same time, improved methods of drilling and commissioning wells were necessary as well as the acquisition of highly specialized pump technology to move water from increasingly substantial depths. As a result, Highland Valley Copper has managed to increase pumping yields to levels of 25,000 L/minute while average depths have nearly doubled from what they were only a few years ago. Future dewatering requirements are significant and it will be necessary to utilize recent experience to forecast targets and maintain flow rates in operating conditions that continue to become more demanding and complex.
Mots Clés:
Dewatering, Pumps, Highland Valley Copper, Open pit mining, submersible pumps, Planning, deepwells, Pumping, Groundwater, dual rotary drilling
