Water quality control at Bell Mine for a supernatant discharge to Babine Lake

"Maclaren Forest Products Inc.Lime is commonly used for the neutralization of acid, and the removal of heavy metals in mine waste waters. However, the precipitation of heavy metals as hydroxides must take place under conditions of controlled pH, to produce minimum concentrations of dissolved metals. An account is presented explaining the concepts applied to lime-treatment processes at Bell Mine during the period of a supernatant discharge to Babine Lake; October 18, 1982to January 25, 1983. IntroductionBell Mine of Maclaren Forest Products Inc., Babine Mining Division, an open-pit copper mine, is located on Newman Peninsula, Babine Lake approximately 65 kilometres northeast of the town of Smithers, British Columbia (Fig. 1).A depressed market for copper metal in 1982 forced a management decision to suspend operations at the mine for an indefinite period from October 3 I, 1982. For some time prior to the mine closing date, mine management was concerned about the increasing level of supernatant in the tailings pond , and its possible effects on the stability of the dam when cycloning of mill tailings ceased. Consideration of these potential hazards led to an application being filed with the Provincial Waste Management for a permit to discharge the excess water to Babine Lake. This large lake, an important link with several significant salmon spawning sites, is a major contributor to the British Columbia commercial fishing industry. Jurisdiction for the environmental affairs in the area is shared by the Department of Fisheries and Oceans, the Environmental Protection Service, and the Provincial Waste Management Branch. These agencies were directly concerned in the formulation of discharge permit following joint consultation, and exchange of information with the company on environmental concerns. An approval was finally granted to discharge approximately 1,000,000 cubic metres of supernatant from the tailings impoundment at Bell Mine into Hagan Arm, Babine Lake from October 18, 1982 with a daily discharge not to exceed 9000 cubic metres. Provisions were made that a particular discharge procedure be followed, and that the company would be responsible for setting up a sampling and monitoring program to safeguard the quality of the effluent."