Post closure human health and ecological risk assessment at Teck Cominco's Kimberley operations, BC : overview of regulatory process and findings of the problem formulation Higgins, C. A.; Wilson, R. M.; Sandstrom, N.; Dawson, Bruce B.; Mann, Gary S. (Gary Seymour), 1966-; Allard, P. J.; Baker, Randy F.
The Sullivan sulphide ore body was discovered in 1892; Teck Cominco Metals Ltd. (Teck Cominco) and its predecessors operated underground lead/zinc mining, milling, and other industrial operations from 1909 until December 2001. The total area of land disturbance (mine, associated facilities and waste impoundments only) is on the order of 1,090 ha. Since the 1960s, Teck Cominco has been planning and implementing measures to restore and/or protect the environment impacted by mining activity. In 1991, at the request of the BC Ministry of Energy and Mines, Teck Cominco developed a comprehensive Decommissioning and Closure Plan that is being implemented under Mines Act Permit M-74. The BC Ministry of Water, Land and Air Protection required site investigations and remediation to address contaminants and impacts not addressed in the Closure Plan (e.g., hydrocarbons). Remediation has included contaminant removal (where possible), and risk assessment/risk management, to meet Teck Cominco’s post closure objectives. The main contaminants are metals generated directly from mining activity (e.g., waste rock piles, tailing impoundments, fugitive dust) and from subsequent releases due to acid rock drainage. The Risk Assessment (RA) Problem Formulation (PF) for human, terrestrial and aquatic components is complete, and the RA is nearing completion. The PF process was successful in screening out receptor/contaminant combinations where negligible risks were predicted using conservative assumptions, and in identifying specific receptor/contaminant combinations that require additional investigation. The St. Mary River and Mark Creek are identified as primary receiving environment components and are key drivers of the RA. A hydrogeological and geochemical assessment of upgradient waste impoundments is being conducted concurrently with the RA to allow predictions of post closure groundwater and surface water concentrations. This paper focuses on the environmental regulatory framework, and the challenges faced due to two parallel regulatory processes under the Mines Act and Waste Management Act. An overview is also provided regarding the approach taken to conducting this RA at a large mine site where both anthropogenic activities and natural mineralization have resulted in elevated metals concentrations.
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