Lead-zinc smelter facility closure planning

Located in northern New Brunswick, a lead-zinc smelter facility spanning 150 hectares had been in continuous operation for over five decades. The site included a complex network of industrial infrastructure, including a smelter, fertilizer plant, sulfuric acid plant, material handling systems, slag piles and a designated hazardous waste area. 

With the facility approaching the end of its operational life, we were engaged to undertake a closure plan prefeasibility study to support future decommissioning and site rehabilitation. The challenge involved developing a comprehensive strategy to address legacy environmental impacts while ensuring regulatory compliance and long-term sustainability. Key components of the study included evaluating hazardous waste disposal options, preparing demolition plans and conceptualizing remedial actions such as in-situ capping of contaminated soils. The closure required a Class 3 cost estimate to close the site in a manner that was environmentally and economically sound, in compliance with applicable provincial and federal regulations and standards and maximized the potential end use value of the site. Unique project challenges included the size of the site, general lack of current environmental data, health and safety requirements for conducting work at an active smelter and tight timelines to complete the work.

Our team brought deep technical expertise and a long-standing familiarity with the site, having completed a prior series of environmental assessments. These earlier investigations included a preliminary facility decommissioning study, a detailed Phase III Environmental Site Assessment (ESA), ecological surveys with rare plant inventories and a Naturally Occurring Radioactive Materials (NORM) survey of selected buildings. This work was complemented by a community-wide off-site soil sampling initiative, stakeholder engagement and a residential remediation program. 

Building on this foundation, the closure plan prefeasibility study focused on key infrastructure across the site, including the smelter, fertilizer plant, materials handling areas, slag piles, freshwater pumphouse and pipeline, conveyors to the adjacent port and a rail spur line. We conducted a comprehensive hydrogeological study and data gap assessment to evaluate subsurface conditions, particularly in areas historically used for process sludge storage that could impact nearby surface water receptors. A targeted NORM and hazardous materials survey was also completed to quantify residual contamination in the fertilizer plant area, informing future remediation and disposal strategies. 

To support decision-making, we compiled all historical and current environmental data (over 30,000 records spanning from 1988 to present) into a customized geographic information system (GIS) platform, eDATpro. This interactive tool integrated site maps, sampling databases, 3D visualizations, borehole logs and photographic records to streamline data management and spatial analysis. 

As part of the decommissioning and demolition planning, the team conducted a detailed infrastructure assessment, cataloguing equipment inventories, salvageable materials, pre-demolition cleaning requirements and waste disposal needs. Closure options were evaluated through a structured analysis considering regulatory and corporate alignment, health and safety, cost, schedule and long-term liability. Preferred methodologies were selected in collaboration with the facility owner, culminating in the development of final closure strategies, cost estimates and implementation timelines.

This facility closure project leveraged proven methodologies from similar industrial decommissioning projects completed across northern New Brunswick. Complex regulatory environments were efficiently managed, while long-term environmental impacts and financial liabilities were minimized.  

Innovative, sustainable and cost-effective closure strategies were implemented across the site. A key feature of the plan was the integration of passive water treatment systems using engineered wetlands, paired with a vegetated soil cover. This nature-based solution was designed to attenuate metal-impacted groundwater and surface water, eliminating the need for costly mechanical treatment systems post-closure. It also provided long-term protection for human health and ecological receptors. 

Despite the complexity of the site and scope of work, the field programs and closure plan prefeasibility study was completed within a six-month timeframe, meeting the project’s accelerated schedule. Following the facility’s closure announcement, the study served as the foundation for the environmental impact assessment, supporting regulatory approvals and guiding the next phase of site rehabilitation.