Engineering solution to save Pacific salmon in the Tsolum River

Engineering solution to save Pacific salmon in the Tsolum River

In partnership with local communities, the BC provincial government and local industry, SRK developed a long-term solution to control copper-bearing drainage that has been contaminating the headwaters of the Tsolum River for decades. The objective of the project was to improve water quality, return salmon, steelhead and cutthroat trout to local waters, and support the goal of sustainable BC fisheries.

After briefly operating from 1964 to 1966, the Mount Washington copper mine has been a major source of acid rock drainage (ARD) entering the Tsolum River near Courtenay, BC. Previous remediation projects have been only partially successful at controlling the problem and treating the copper bearing discharge from the mine site.

Beginning in 1987, federal and provincial agencies funded studies, monitoring and on-site works to address the ARD problem. Between 1988 and 1992, the B.C. Ministry of Energy, Mines and Petroleum Resources (MEMPR) spent $1.5 million on site remediation, hiring Steffen Robertson and Kirsten (Canada) Ltd. (SRK) to design and install a till cover, the primary focus of the remediation work. The cover was placed over waste rock in the East Dump located below the North Pit, to prevent oxygen and water from contact with the waste rock. Other smaller scale Ministry activities included testing an experimental asphalt emulsion/geotextile cover, and applying calcium hydroxide to the pit walls and floor to attempt to raise the pH and reduce metal loading. Since SRK’s initial work in 1988 and 1989, the site has been the subject of numerous government, consultant and academic reports and assessments.

Water monitoring results from 1993 to 1996 revealed there had been little reduction in copper levels. However, since 1998, water quality monitoring has shown sustained reductions of approximately 50%, which is believed to result from the onsite works.
In 2003, industry, government and the local community formed a unique partnership to seek long-term solutions. In 2003, the partnership asked SRK to develop a long-term remediation plan for the site.

In 2008, three BC Ministries announced funding for the project. Quantum Environmental, SRK and Stantec were hired to place a low infiltration cover on the North Pit of the mine. Work on the project started in 2009 and included constructing an underdrain system, installing a bituminous liner, and placing and revegetating a soil cover.

Early results have been encouraging; average copper loadings leaving the site dropped 77%. The project is expected to be completed in summer 2011, with post-construction monitoring carried out by the Tsolum River Restoration Society and the Ministry of Environment.

Peter Healey: phealey@srk.com

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