The Faro Mine Complex (FMC) is one of the largest and most complex contaminated sites in Canada. Located in a remote area in the south central Yukon, Faro was an open-pit lead-zinc mine that operated from 1969 until 1998. The FMC site covers approximately 2,500 hectares and includes 70 million tonnes of tailings and 320 million tonnes of waste rock. Both the tailings and waste rock contain high concentrations of heavy metals that could leach into the environment. A care and maintenance regime, including diversion of clean surface water and collection and treatment of contaminated water, is currently in place at the site.

The diverted water courses include Faro Creek, Rose Creek and Vangorda Creek. These diversions were installed up to 50 years ago by the mine operators to direct surface water around the active mine pits. Although designed to be temporary, the diversions presently remain in service to prevent clean water from mixing with contaminated water. As the diversions have aged, new challenges to the management of clean water have developed.

The operation of the FMC resulted in the creation of three large open pits and a large tailings impoundment area that presently contain contaminated water. Acid mine drainage caused by weathering of the waste rock has resulted in contaminated water characterized by low pH values and high metal concentrations. The primary contaminant of concern in the impacted water is zinc. To minimize the impact of the zinc on the environment, two water treatment plants are used to reduce contaminated water metal concentrations to below the acceptable criteria for release from the site. In 2016, the water treatment plants treated >1billion gallons of contaminated water, for release to the environment.

This presentation will discuss the past and present efforts required to successfully address the many water management challenges at the FMC.

The former Britannia Mine operated near Vancouver, Canada from 1904 to 1974, and at its peak was the largest copper mine in the British Commonwealth. During its 70 years of operation it generated more than 40 million tonnes of tailings, much of which was deposited in the adjacent marine environment of Howe Sound and used as fill along the Britannia Beach shoreline. The acid-generating tailings and upland former mine workings leached dissolved copper and zinc into Britannia Creek (which drains to Howe Sound) as well as directly into Howe Sound until recently when the provincial government began an ambitious remediation program intended to intercept, collect and treat water-borne metals discharging to the environment. Monitoring of water quality and intertidal ecology is providing information confirming that environmental conditions are improving along a majority of the shoreline and that residual impacts appear to be localized around areas of historical infrastructure. 

A remediation program or risk manager for a contaminated site needs to know “how clean is clean enough?”. The objective of the initial remediation activities was to address severe, acutely lethal conditions that posed a mortality hazard to out-migrating juvenile salmon and this objective has been achieved. As site characterization continues and additional remediation is undertaken, realistic remediation goals need to be defined. In the case of the Britannia Mine, the return of the shoreline to pre-development conditions is likely not possible as the long-term operations of the mine resulted in significant filling and replacement of the natural shoreline with engineered surfaces (e.g., rip rap). Moreover, the construction of a transportation corridor adjacent to the shoreline will limit the use of intrusive remediation techniques. “Resource conservation objectives” (RCOs) have thus been articulated to help direct remediation efforts. The RCOs consist of a description of important shoreline ecological functions and/or features as well as acceptable levels of those features that are based on: 1) the results of the monitoring program which provide an understanding of the ecological conditions of near-field and reference areas, including natural variability; 2) the broader mandate of environmental agencies to maintain and/or or restore a healthy productive ecosystem; and, 3) the local community’s desire for environmental improvement but not at all costs.  

As part of the long term Giant Mine Remediation Plan, a new Effluent Treatment Plant (ETP) will be constructed to treat water from the underground mine. The first phase of this project was to choose a discharge location, along the shoreline of Yellowknife Bay, for the treated effluent. As per the direction of the Mackenzie Valley Review Board the treated water is required to be discharged through a near shore outfall. The main focus of this presentation will be to identify how a location was chosen and the designs considered.

Traditionally, direct remedial measures for underwater contaminated sites in sensitive ecological habitats, such as river sediment, lakes, wetlands, or other ecologically valued areas, are not undertaken without significant cause. Responsible contaminated site professionals are hesitant to implement potentially destructive remedial measures in sensitive habitats for fear that the “cure will be worse than the disease”. Indeed, as many case studies reinforce, ecological risk assessments often lead to sustainable remedial approaches that minimize habitat destruction and adopt small-scale, incremental or interceptor type remediation or, more often, long-term monitoring. In effect, contaminated site managers would rather natural degradation, with little or no human intervention. 

Now, consider a case where historical chemical impacts deposited into a sensitive habitat were clearly shown to negatively impact the aquatic habitat to such an extent that fish and invertebrates were avoiding the impact zone. Further, consider that 15 to 20 years of natural attenuation appeared to be having little to no effect. Consider that environmental discharge approvals related to the operation of a key industrial wastewater treatment asset is dependent on the improvement of the degraded habitat by a measured increase in the variety and populations of the aquatic species typical of this estuarine environment. What solutions would be viable, what could be permitted, and what solutions would ultimate be feasible?

The presentation will demonstrate practical remediation underwater contaminated sites can be achieved when the risk of the status quo outweighs the risk of action from environmental, social and economical perspectives. This case study examines practical approaches undertaken to manage potential induced ecological risk during sediment remediation. The presentation will examine the planning, permitting, implementation, restoration, and monitoring of mass removal of river sediment, followed by a substrate restoration/replacement. The presentation will also explore innovation from a forward-looking permit approach, the equipment chosen to complete the work, and potential habitat enhancements.

The Randle Reef Sediment Remediation Project is the planned clean up of a severely contaminated portion of Hamilton Harbour in Lake Ontario. Randle Reef is the largest PAH contaminated sediment site (695,000 m³) on the Canadian side of the Great Lakes and the clean-up project consists of the construction of an engineered containment facility (ECF) as well as the dredging and placement of contaminated sediment from outside the facility into the ECF. The project consists of three stages:

1. Construction of the ECF;
2. Dredging of the contaminated sediment outside the ECF and placement within; and,
3. Capping of the ECF.

The concept for the Randle Reef Sediment Remediation Project was developed in 2003 and incremental design work and consultation was completed over the following years. Funding and partnership agreements for the project were established in 2013. Funding for the $138.9 million project is provided by multiple parties including Environment and Climate Change Canada, the Ontario Ministry of Environment and Climate Change, the Hamilton Port Authority, US Steel Canada, the cities of Hamilton and Burlington and the Region of Halton.

In July 2015 Public Services and Procurement Canada successfully re-tendered and awarded the Stage 1 ECF construction contract to McNally Construction from Hamilton, Ontario. The successful 2015 tender followed the original tender in 2014 (where all bids received were over budget), a re-evaluation of the project including industry consultation, and an alteration of the ECF design and other project components to achieve cost savings. A service contract was also awarded in July 2015 to Riggs Engineering from London, Ontario, for Stage 1 construction, contract administration and resident site services.

Site work began at Randle Reef in April 2016 following the mobilization of marine equipment from Ontario, Quebec and Nova Scotia, and the delivery of steel sheet piles (SSP) from Iuka, Mississippi. Construction of the first half of the ECF, consisting of driving a double SSP wall and dredging and backfilling between the walls, was completed on schedule in December 2016. Following a planned winter shutdown, construction of the second half of the ECF is currently underway with an expected completion date of December 2017.

An environmental monitoring plan (EMP) has been implemented during Stage 1 construction.  Elements of the EMP include water quality, air quality and contaminated sediment removal verification along with a communication plan. Air quality is a potential concern during Stage 1 of the project due to contaminated sediments being exposed to the open air during mechanical dredging.  The primary contaminant of concern is naphthalene due to its volatility and odour.  Perimeter monitoring with photoionization detectors (PIDs) are used as a screening tool for potential exceedances of air quality criteria.

As there are many partners involved in this project, a communication plan was required to be part of the EMP.  The plan identifies how monitoring exceedances will be communicated and by whom.  This is extremely important for this project as partners need to be aware of site activities and is further complicated by the fact that the province is not only a partner, but also retains its enforcement duties.   

This presentation will provide background on Stage 1 of the Randle Reef Sediment Remediation Project, the progress and status of construction, and the implementation of the environmental management program.