Water treatment of molybdenum was authorized in July 1997 at the Brenda Mine site. Rain and snowmelt that have contacted the molybdenum rich rock that remains in on site stockpiles is diverted to catchment areas on the property. The water is then pumped to the water treatment plant, which reduces the molybdenum concentrations from 2.6 miligrams per litre (mg/L) to less than 0.06 mg/L. Water treatment will continue at the site until the concentration has been reduced to natural background levels.
In general, the geochemistry of the rock types both in the rock piles, low-grade ore material and tailings suggest that materials will remain neutral to alkaline. Molybdenum leaching from the mine rock at neutral pH is the most important process that affects water quality at the Brenda Mine site. A detailed test program was completed to characterize the mine rock in terms of particle size and molybdenum content and leaching rates were measured in laboratory columns. The modelling results indicated that leaching will likely continue for more than 100 years.
Treatment solids are produced by the water treatment plant during removal of molybdenum from site waters. The Phase 1 sludge storage facility was designed to store about five years of treatment solids production and was commissioned in the spring of 2002. The actual rate of solids accumulation in the impoundment was estimated to be on the order of about 400 cubic metres per year (m3/a). Following natural dewatering and drying, the treatment solids are currently packaged into bags for shipment to a third party for molybdenum processing.
As a requirement of our discharge permit, our monthly water quality newsletter can be found below, a link to the newsletters can also be found on the District of Peachland website.
Glencore continues to monitor air quality at the Brenda Mine site, vegetation is maintained to limit dust and greenhouse gasses are reduced whenever possible. This includes choosing environmentally conscious lighting, upgrading infrastructure to increase efficiency, and reducing travel to site when possible.
Reclamation of the land was completed in 1998; all items outlined in the detailed closure plan were achieved with great success. Maintenance of the land continues at the site, with regular fertilizing, invasive species management, land stability reviews and vegetation removal where required.
A wild ruminant study was completed at the Brenda Mine site in 2000 to assess the potential effects of molybdenum uptake in vegetation. Although elevated levels of molybdenum were measured in vegetation on site, there was no indication of molybdenum toxicity in the abundant on-site deer population. A vegetation sampling program at the Brenda Mine Site was completed in 2007.