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Risk Based Closure of Pulp and Paper Contaminated Sediments at Peninsula Harbour, Ontario with Application of Thin Layer Sand Cap Remedy
David Wilson1, Ronald Hewitt2, John Bleiler3, Carsten Floess3
1AECOM Canada Ltd.
2Public Services and Procurement Canada
3AECOM

The objective of this presentation is to detail an innovative sediment remedial approach, thin layer sand capping, as part of a risk-based accelerated natural recovery strategy to site closure and to provide early monitoring results of success to-date.

Abstract

Peninsula Harbour is a 12 km2 (approximately 3,000 acres) embayment off the northern shore of Lake Superior, Canada, that was identified as an area of concern (AOC) in 1985 by the Water Quality Board of the International Joint Commission. Elevated concentrations of mercury and polychlorinated biphenyls (PCBs) in sediment and fish and extensive wood fibre and waste residues were identified within Jellicoe Cove in the southeastern portion of the Harbour and, with risks related to First Nations and public consumption of fish the site, was deemed to require active sediment management. Various sediment management options were assessed. Installation of a thin layer cap (TLC) was selected as the primary active remedy by Environment and Climate Change Canada and the Ontario Ministry of the Environment, in consultation with the First Nations and other local stakeholders. The TLC, covering approximately 252,000 m2 (62 acres), included placement of approximately 15 cm of clean sand on top of previously identified mercury and PCB contaminated sediments with the intention to isolate underlying contaminated sediments and to provide a substrate for restoration of clean sediment, recolonized benthic communities and reestablishment of aquatic vegetation. The construction documents and environmental assessment were finalized in 2011 with construction of the remedy in 2012. A long-term monitoring program was designed to assess improvements in Jellicoe Cove sediment and biological communities following TLC construction and continued natural deposition over a 20-year period. The long-term goals are to reduce the risks associated with the contaminated sediment and restore environmental conditions in the AOC. The sediment management project is the last remedial action required to delist Peninsula Harbour from the list of Great Lakes Areas of Concern.

This presentation will provide an overview of historical data collection on the Cove, how TLC was selected, a summary of the design and construction, and a detailed discussion and status update of long term monitoring data collection as relate to the long-term goals of the project.

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A Comprehensive Overview of Setting Water Quality Limits for a Large Scale Contaminated Sediment Remediation
Matt Graham, Environment and Climate Change Canada

The objective of this presentation is to cover the derivation of water quality limits for the large scale sediment remediation project as well as how these limits were integrated into a comprehensive water quality monitoring program. It will provide information and guidance to others managing contaminated sediment remediation projects.     

Abstract

The Randle Reef Sediment Remediation Project in Hamilton Harbour is the largest PAH contaminated site on the Canadian side of the Great Lakes. The remediation project is managing 695,000 cubic meters of highly contaminated sediment through a combination of hydraulic dredging, isolation capping and thin layer capping. All dredging projects require water quality limits to prevent the dredging itself from causing adverse effects to the ecosystem. Contaminated sediment dredging must consider negative effects from both the physical aspects of dredging (introduction of particles into the water column) as well as chemical effects from contaminants in the suspended and dissolved state. They must also develop comprehensive and practical means to measure these parameters in the field. This presentation will cover the derivation of water quality limits for the Randle Reef project as well as how these limits were integrated into a comprehensive water quality monitoring program.

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 Water Management At Faro Mine Complex, Faro, Yukon
James Carss1 and Thaidra Sloane2
1Parsons Inc.
2Government of Yukon

The objective of this presentation is to provide an update on the ongoing activities at the Faro Mine Complex, one of Canada's most complex contaminated sites. 

Abstract

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.

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Using Biomonitoring Data to Integrate Ecological Function with Remediation Goals for the Historic Britannia Mine
Barbara Wernick, Golder Associates Ltd.
 

The objective of this presentation is to discuss the use of biological monitoring data to integrate the ecological function of a marine shoreline with realistic remediation goals for an abandoned mine site.

Abstract

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.  

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 In-situ Enhanced Bioremediation Treatability Study of RDX Contaminated Soil and Groundwater at a Former Military Demolition Range

Louis-B. Jugnia1, Dominic Manno1, Meghan Hendry2
1National Research Council Canada
2Department of National Defence

The objective of this presentation is to discuss the use of biological monitoring data to integrate the ecological function of a marine shoreline with realistic remediation goals for an abandoned mine site.

Abstract

The effect of a carbon substrate (waste glycerol) on RDX (hexahydro-1,3,5- trinitro-1,3,5-triazine) biodegradation was assessed through a pilot-scale study at a former military demolition range (Garrison Petawawa, ON). For this, a large-scale in-situ treatment of a suspected RDX soil hotspot, as well as the associated groundwater, was conducted using the application of surficial waste glycerol. Results indicated that RDX biodegradation by anaerobic indigenous microorganisms was improved with the added carbon substrate. In fact, no RDX was detected in soil samples collected from the treated area and there was an increase in total organic carbon (TOC) and volatile fatty acids (VFA) concentrations in three of the monitoring wells under consideration. Conjointly, there was an important decrease of RDX concentrations in four out of five groundwater samples from monitoring wells under study, with concentrations reduced to below detection limits in three wells. All three RDX nitroso-degradation products were detected in groundwater samples, suggesting anaerobic degradation. These results offer good prospects for the use of biodegradation approaches in the addressing energetics (e.g., RDX) contaminated soils. 

 
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 Giant Mine Effluent Treatment Plant
Karen McLean1 and Jennifer Singbeil2
1Indigenous and Northern Affairs Canada
2Public Services and Procurement Canada

The objective of this presentation is to discuss how we choose the discharge location for the ETP and the conceptual design. This will include: the consultation completed; the Option Evaluation Model used to choose a location and how we developed it; the cooling options discussed; and, results of the mixing studies in each of the areas considered. 

Abstract

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.

The second phase of the project, which will commence in 2017, will be to complete a Baseline Aquatic Study in the location of the outfall. This will also entail additional sediment sampling and a more detailed mixing study at the chosen location. A pilot plant may also be implemented and operated for three months in 2017 in order to test the treatment method for parameters of concern in the mine effluent. 

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 Remediation and Restoration of an Estuarine River: A Case Study for Impacted Sediment Remediation and Replacement
Jeff Earle, Dillon Consulting Limited

The objective of this presentation is to discuss remediation in a sensitive underwater habitat.

Abstract

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.

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 The Randle Reef Sediment Remediation Project: Implementation of Stage 1 Construction and Environmental Management Activities
Erin Hartman1 and Dave Lawrence2
1Environment and Climate Change Canada
2Public Services and Procurement Canada

The objective of the presentation is to discuss the current status of Stage 1 of the Randle Reef Sediment Remediation Project, and the on-going environmental monitoring and management activities.

Abstract

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.

 
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Knowing Your Contaminant and Characterizing it to Efficiently Remediate Sediment
Jason Christensen, Keystone Environmental Ltd.

The objective of this presentation is to discuss utilizing innovative investigation methods with proper planning to develop a sediment remediation plan. With the high cost of completing sediment remediation it pays to take the time and prepare well. 

Abstract

A site located on the shore of Burrard Inlet was formerly occupied by various industrial operations since the early 1900’s. Industrial operations conducted at the site included a pesticide manufacturing facility and a sea to rail freight/ storage that included the transport of copper ore concentrate. The site was extensively filled along the waterfront over a sandstone formation.

Metals contamination was identified in soil, groundwater, and relatively shallow sediment associated with the ore concentrate and fill. The fill contamination is located sporadically at varying depths across the site. Pesticides contamination was identified in groundwater and sediment media. LEPH and PAH contaminated soil and groundwater was identified at depth, from an unknown historical release with a signature consistent with creosote or coal tar. Dense NAPL migrated vertically to the sediment/bedrock interface, and flowed along the surface of the bedrock or within native sediment interbeds. The LEPH and PAH concentration distributions indicate that the original release was confined vertically to within the uppermost weathered bedrock, and horizontally to the east and west.

Several investigation techniques were used to achieve a detailed limit of contamination present that, when combined with a risk assessment, was able to significantly reduce the quantity of sediment to be dredged. The investigation techniques used include:

  • Using a geophysical seismic refraction survey to obtain a detailed mapping of the overburden material interface with the surface of the underlying bedrock and use this to target the investigation;
  • Developing an innovative sampling method to collect discrete water samples from within the sediment and bedrock beneath the ocean floor; and,
  • Analyzing the contaminant characteristics and metals mineral form to determine the bioavailability and potential risk. 

The geophysical seismic refraction survey was developed in concert with existing borehole logs to refine the geophysical interpretation of the bedrock surface. The detailed contour map of the bedrock surface that was generated from the survey provided a key line of evidence regarding the plume migration pathway. The survey data appeared consistent with the bedrock surface configuration that provided stratigraphic control of DNAPL migration. Using a 1mg/L naphthalene isopleth to approximate the extent of residual DNAPL, the contour closely matches areas of bedrock surface depressions indicated by the seismic refraction survey. The results of the geophysics survey were used to target the investigation program and delineate the area of contamination.

During the site investigation an innovative methodology also had to be developed to collect discrete water samples from boreholes drilled into sediment and bedrock beneath the ocean floor. This methodology enabled water samples to be collected from the bedrock with limited turbidity and vertical mixing with the water from above the sampling zone. Custom equipment was set up using inflatable packers to collect discrete samples during sonic drilling from a barge platform.

Sediment samples collected were also analyzed to determine the metal speciation and mineral form. These results were utilized with the porewater results to estimate the bioavailability of the metals and used as an additional line of evidence to support the results of the toxicity testing completed for the risk assessment. The risk assessment developed site-specific toxicity reference values (TRVs) for sediment that were used as the remediation objective. The TRV data were then integrated in the concentration contour plots to define the area of remediation. The remediation areas located within navigational areas were then developed as dredge remediation areas with the other remediation areas devised to be capped.

The detailed investigation, risk assessment and remediation plan were submitted to the Ministry of Environment for an Approval in Principle (AIP). The Ministry of Environment issued the AIP and the remediation is currently underway.