By David J. Penny
In 1930, copper was discovered in the mountains west of Peachland B.C. However, there was virtually no activity surrounding the find until 1954, when Penticton-based prospector, Bob Bechtel, staked a claim. Unfortunately, assays soon indicated that the area’s deposits were comprised of low-grade molybdenum, which, at the time, was not considered a viable source for copper production. Bechtel approached Noranda about mining opportunities, but they declined involvement due to the high costs of processing the ore with the limited technologies that were then available.
In fact, it was not until 1970 that market demands and new mining process technologies had both improved to a point at which copper production from molybdenum became economically feasible. The mine opened in that same year and operated successfully, producing as much as 33,000 tons of copper- molybdenum per day. The copper output was destined for Japan, while the molybdenum was shipped to Europe.
However, in 1990, the Brenda Mine was abruptly closed as a result of seriously depleted ore deposits, as well as grave geological concerns about the incurrence of further damage to the mountain strata. Site reclamation activities had already commenced in 1988, and included contouring and terracing of rock piles, aerial seeding and fertilization, as well as irrigation of newly planted areas.
In 1998, following environmental and technical studies to determine the required remediation for closure, the final Ministry of Environment discharge permit was issued. That same year, a new, $11 million water treatment facility was commissioned to ensure proper operation, maintenance and monitoring of the reclamation efforts at and around the mine site.
MacDonald Creek starts high in the mountains and passes through the Brenda mine site, eventually joining Trepanier Creek, a Kokanee spawning stream that flows into Lake Okanagnan, in the Peachland Irrigation District. Although virtually dry during summer months, the spring melt water flow can be quite significant. So, before the mine was opened, a stream enclosure comprising several kilometers of coated, 1200mm galvanized corrugated steel pipe (CSP) had been constructed to carry the pure mountain water past the mining site. This pipeline was constructed using gasketed, semi-corrugated couplers to minimize leakage, with turnout valves added to facilitate the control of water flow, as required.
When the mine was open and operating, water had been required for the ore milling stage of processing; however, all process waters were treated prior to being discharged from the mine site. Before the treated water was released to the lower creek, strict water conservation, recycling and treatment protocols were put in place. And, although the mine has been closed since 1990, mine leachate water continues to be treated before being released, and this treatment is expected to be a continuous requirement for the next 200 years!
The corrugated steel bypass helps minimize the volume of water requiring treatment. And, to ensure the long-term performance of the pipe, a detailed engineering inspection was commissioned in the Fall of 2010. Results of the inspection showed that, despite more than 40 years of continuous operation, the CSP remains in remarkably good condition and is projected to provide many more years of service, with only minor maintenance and repair required.