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Profile

The Island Copper Mine was a 50,000 tonnes/day open-pit copper/gold/molybdenum/silver mine that opened in 1971 and closed in 1995. Clem Pelletier, Rescan's president, worked at ICM from 1971 until he started Rescan in 1981. It was the first mine in the world to use "engineered" submarine tailings disposal. Nearly 360 million tonnes of finely ground tailings were placed on the seafloor of nearby Rupert and Holberg Inlets without significant long-term effects on benthic life. Upon closure, the open pit was flooded to create a three-layer meromictic lake for passive treatment of acidic, metal-contaminated drainage from on-land waste rock dumps. The discharge from the surface layer of Pit Lake has met all Provincial permit criteria.

Overview

Utah Construction and Mining Co. (now BHP Billiton) prepared the initial conceptual design of the submarine tailings disposal system, and operated and maintained it for over 25 years. During that time, the mixtank and pipeline system was modified and extensive experience was gained in the methods of construction and installation, the effects of seawater corrosion, the wear characteristics of pipes, and the physical and numerical modelling of tailings dispersal and sedimentation. Rescan contributed in all these areas and also designed the mine closure plan, supervised the flooding of the open pit, and continues to study the biogeochemistry of Pit Lake.

Experience

Rescan engineers and scientists contributed much to the design of the submarine tailings disposal system and the mine closure plan. They also conducted a wide range of environmental monitoring programs, including studies of the water quality and biological resources of the watersheds surrounding the mine, the hydrology of the project area, the physical and chemical structure of Pit Lake (including inspection of the mine water injectors using a remotely-operated vehicle), the effects of fertilization upon metal concentrations in the lake, and the mass balance of metals in the lake. Rescan continues to be actively involved in this project.