Sydney Tar Ponds

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The Sydney Tar Ponds contain waste runoff from the Sydney Coke Ovens which were built in the nineteenth century and which operated for more than a century.

The Sydney Tar Ponds were a hazardous waste site on Cape Breton Island in Nova Scotia, Canada.

Located on the eastern shore of Sydney Harbour in the former city of Sydney (now amalgamated into the Cape Breton Regional Municipality), the Tar Ponds form a tidal estuary at the mouth of Muggah Creek, a freshwater stream that empties into the harbour. Over the last century, runoff from coke ovens associated with Sydney Steel Corporation's (SYSCO) now-decommissioned steel mill filled the estuary with a variety of coal-based contaminants and sludge. Efforts to clean up the waterway have been dogged by false starts, delays, and political controversy. After extensive public consultation and technical study, a $400 million CAD cleanup plan, jointly funded by the Government of Canada and Government of Nova Scotia, was announced in January 2007.


Herring gulls resting on a mud flat in the South Pond of the Sydney Tar Ponds, September 2004.

The North Pond and the South Pond have a combined area of 31 hectares (77 acres), and contain 700,000 metric tonnes of contaminated sediments. The nearby coke ovens site spans 68 hectares (168 acres) on a sloping field overlooking the estuary. It contains an estimated 560,000 tonnes of contaminated soil.

A small stream, the Coke Ovens Brook Connector, connects the coke ovens with the Tar Ponds. It served as the main pathway for contaminants migrating from the coke ovens to the Tar Ponds. To the east of the coke ovens, and uphill from them, an abandoned municipal dump served as an additional source of contaminated groundwater, or leachate.

The polluted sites lie in the middle of the former city of Sydney (estimated population 25,000), now part of the Cape Breton Regional Municipality (CBRM) (2001 population 105,968).

Almost all contaminants result from coke production, one of the most common industrial processes of the 19th and 20th centuries. While almost all of the contaminants derive from coal, the Tar Ponds include two pockets containing an estimated total of 3.8 metric tonnes of polychlorinated biphenyls (PCBs). PCBs are known to cause cancer, and the higher per capita incidence of cancer and cancer related death in Sydney area residents can be attributed to their presence[citation needed].


In 1901, investors from Boston formed the Dominion Iron and Steel Company Limited and opened a major steel works on Sydney Harbour. Sydney had everything needed for steelmaking, including locally mined coal, nearby iron ore from Bell Island and limestone from Aguathuna (both in Newfoundland), a good harbour for shipping, and plenty of cooling water. By 1912, the mill was turning out nearly half of Canada’s steel production.

The steel mill, and the nearby coal mines that fuelled it, operated for nearly a century under a variety of owners including Dominion Steel Company (1912), British Empire Steel Corporation (1921), and Dominion Steel and Coal Corporation (DOSCO) after 1930. An economically failing DOSCO was purchased by A.V. Roe Canada in 1957, which was in turn dissolved, and its assets, including DOSCO, purchased by Hawker Siddeley Canada in 1962. By the mid-1960s, Hawker Siddeley began to close money-losing subsidiaries and identified DOSCO's coal mines and steel mill as candidates for closure. By 1967, DOSCO announced plans to close the mill and began phasing out the coal mines. In response to the threatened loss of thousands of jobs in a region with poor economic prospects, the government of Nova Scotia expropriated the steel mill, renaming it Sydney Steel Corporation (SYSCO). The government of Canada expropriated DOSCO's coal mines at the same time, as well as the coke ovens that produced the pollution flowing into the Tar Ponds, naming this operation Cape Breton Development Corporation (DEVCO). SYSCO purchased the coke ovens from DEVCO in 1973.

Dominion Tar and Chemical Company Ltd (Domtar) operated a coal tar refining plant and a coal tar storage facility in Sydney from 1903-1962. This facility was situated directly adjacent to and north of the coke oven operations. It diverted coal tar from the coke ovens, refined it, moved it through pipes, and stored it in tanks for shipping elsewhere. Domtar ceased operations in Sydney in 1962 abandoning its storage tanks, waste disposal lagoons, pipes, buildings and equipment. Domtar conducted little or no clean up of the site. A large tank, referred to as the "Domtar tank", remained in place adjacent to the coke ovens site into the 2000s, measuring 28 m (92 ft) in diameter and 6 m (20 ft) high. It contained materials abandoned by Domtar and other materials added in the years since the facility's abandonment.

By the mid-1970s, the environmental movement was gaining headway in North America, and concern about pollution from the steel mill and coke ovens was rising. In 1982, scientists from the Department of Fisheries and Oceans discovered polycyclic aromatic hydrocarbons (PAHs), a family of chemicals produced by incomplete combustion of organic material, in lobster caught in Sydney Harbour near Muggah Creek. They ordered the South Arm of the harbour closed to lobster fishing, and fingered the Tar Ponds as the likely source of contamination.

The discovery increased pressure to close the decrepit coke ovens, which finally ceased production in 1988. Underneath the coke ovens site were approximately one hundred and sixty one kilometres of underground pipes. These pipes were used to move chemicals throughout the coke ovens and steel plant site. Despite the fact that these pipes contained a mixture of dangerous, toxic and potentially explosive substances, many were never purged of their contents when the coke ovens operations ceased. SYSCO converted to an electric arc manufacturing process in 1990, and stopped production altogether in 2000. The mill is now dismantled.

In 1986, Canada and Nova Scotia signed a $34-million agreement to dredge the Tar Ponds and pump the sediments through a mile-long pipeline to a temporary incinerator and power plant. After many delays, the incinerator was completed, and passed required air emissions tests, in 1994. However, the pipeline system proved unable to handle the thick, lumpy Tar Ponds sludge, and the project was abandoned in 1995.

In 1996, the Nova Scotia government proposed a plan to bury the Tar Ponds under slag procured from the steel mill. By this time, the project had attracted local critics, who condemned the plan.

In 1999, the federal, provincial, and municipal governments jointly funded a community organization, the Joint Action Group (JAG), with a mandate to seek community consensus on cleanup options. The three governments also embarked on detailed environmental site assessments, and a variety of preliminary cleanup projects. Although JAG held more than 950 public meetings, no clear consensus on cleanup technologies emerged. Governments, meanwhile, generated more than 620 technical and scientific reports on the problem, and possible solutions.


On May 12, 2004, the Governments of Canada and Nova Scotia announced a 10-year, $400 million CAD plan to clean up the Sydney Tar Ponds and Coke Ovens. The plan[1] called for PCB-contaminated sediments to be destroyed in an approved PCB incinerator to be set up temporarily at a decommissioned industrial facility five kilometers east of the coke ovens. Remaining materials would be treated in place and then contained within an engineered containment system.

Byproducts from coke ovens that operated for 88 years on this site created run-off which contaminated the Muggah Creek estuary, creating the Sydney Tar Ponds. The coke ovens plant was demolished in the early 1990s, leaving this empty field which will be rehabilitated as part of the Tar Ponds project.

At the Tar Ponds, treatment will consist of Solidification / Stabilization (S/S) with Cement, a process by which contaminated sediments are mixed with Portland cement powder or similar hardening agents. At the coke ovens, contaminated soils will be treated with a form of bioremediation known as land farming, in which hydrocarbon-eating bacteria and nutrients are tilled into the upper surface of the soils. The sites will then be contained within a layered cap and impermeable sidewalls, and then landscaped for as yet undetermined future use.

A special operating agency of the Nova Scotia government, the Sydney Tar Ponds Agency, will manage the cleanup on behalf of the two governments, in partnership with the Department of Public Works and Government Services which is the lead federal agency. Fifteen community groups in such fields as environment, health, business, labour, religion, recreation, municipal government, and higher education, contribute delegates to a Community Liaison Committee that serve as a sounding board for project managers during the cleanup. The cleanup is done by Muggah Creek as of 2012 and on August 11, 2012 they opened the Ferry Street bridge for walkers and bikers and August 13, 2012 they opened it for cars.


Establishing a cleanup plan for the Tar Ponds and coke ovens site has taken more than 22 years. Hundreds of volunteers contributed more than 100,000 hours to the Joint Action Group's search for acceptable cleanup options. JAG and its government partners have attracted vocal critics, most prominently Sierra Club Canada. Delays in getting the project started have left many residents frustrated.

Opinions divide on the best cleanup method. Some residents favour digging up and destroying all of the contaminants. Others prefer not to disturb the contaminated material at all. Sierra Club Canada opposes plans to incinerate the PCB materials in favour of novel destruction technologies such as hydrogen reduction and soil washing. Project managers say the community has asked that only proven technologies be used.

In 2005 and 2006, the Sydney Tar Ponds Agency has undertaken four preliminary cleanup projects, including the re-routing of the Coke Ovens Brook Connector to a less contaminated area, and the construction of a rock barrier at the boundary between the Tar Ponds and Sydney Harbour. The preliminary projects are intended to prevent further environmental damage while the larger cleanup is assessed.

In July 2006, the environmental engineering firm EarthTech, Ltd., completed a preliminary engineering design for the big cleanup. A contract for the final engineering design and construction oversight was expected to be set by September 2006.

Environmental impact assessment[edit]

Through the winter of 2005, controversy raged as to the type of environmental impact assessment the Government of Canada should require for the Tar Ponds cleanup. The choice boiled down to the two most rigorous forms of assessment allowed under the Canadian Environmental Assessment Act[2] a comprehensive study, conducted by remediation experts within Public Works and Government Services Canada, and a panel review, conducted by a group of experts from outside government, who would hold formal public hearings.

The Government of Nova Scotia, the Cape Breton Regional Municipality, and a broad coalition of local business, labor, and health organizations favored a comprehensive study, which has half as many steps as a panel review. They argued that after 950 public meetings and 620 technical reports, the issue had been studied and debated enough, and it was time to get on with the cleanup.

The Sierra Club of Canada favored a panel review as the only way to ensure necessary scrutiny of plans to incinerate PCB contaminated material, and to guarantee consideration of alternative technologies.

On May 2, 2005, federal Environment Minister Stéphane Dion and Public Works Minister Scott Brison sided with the Sierra Club, ordering a panel review. In the face of predictions that the decision would delay the cleanup and add to its cost, Dion directed the panel to complete its work by June 30, 2006, and not to make recommendations that would drive cleanup costs beyond the $400 million Ottawa and Nova Scotia had already committed.

The province reluctantly agreed to participate, and the joint panel review held three weeks of sparsely attended hearings in April and May 2006. The panel planned to report by July 13, 2006.


After decades of study, the federal and Nova Scotia governments concluded that the best way to deal with the Sydney Tar Ponds is to stabilize, solidify, and contain the contaminated material. In January 2007, officials from Ottawa and the province announced a $400-million plan to solidify the toxic sludge using the Solidification / Stabilization (S/S) with Cement method. This technology was preferred over a controversial proposal to incinerate some of the 700,000 tonnes of sludge. Nordlys Environmental LP and ECC were awarded a $52-million contract in October 2009 to begin S/S operations.

Environmentalists and local residents continued to worry officials would incinerate some of the material, though Federal and provincial officials claimed the S/S method they had chosen would stabilize the 100-hectare site without producing any adverse health or environmental effects. One way of verifying the potential for adverse health or environmental effects during remediation and clean up of the Sydney Tar Ponds and Coke Ovens site was via environmental effects monitoring prior to and during remediation activities. Dillon Consulting Limited was awarded the contract to monitor changes in chemical contaminants in groundwater, surface water and in the marine environment in Sydney Harbour during baseline (pre-construction / remediation) and during construction / remediation.[3] The marine environment in Sydney Harbour was monitored as contaminants released via Muggah Creek have historically impacted harbour sediments and marine biota, so the harbour marine environment is considering one the receiving environments if contaminants continue to be released.[4] Monitoring of Sydney Harbour sediments prior to and during remediation has not revealed evidence of adverse health or environmental effects due to remediation activities, and sediment quality continues to improve due to natural recovery processes (i.e., burial of historically contaminated sediments by uncontaminated material).[5]

The first phase of the project was completed in mid-December 2009 and work would continue with Phase 2 in the spring of 2010. Eventually the area will be covered with an impermeable barrier, soil, and finally grass. Parts of the restored site may eventually be used for recreational purposes.


  1. ^ Project Description—Remediation of the Sydney Tar Ponds and Coke Ovens Sites—executive summary. AMEC Earth and Environmental, 2004
  2. ^ Canadian Environmental Assessment Act ( 1992, c. 37 )
  3. ^ Dillon Consulting Limited. (2010). Environmental Effects Monitoring and Surface Water Compliance Monitoring Program: pre-construction/baseline report (final). Volume I of II. Nova Scotia: Sydney Tar Ponds Agency. http://
  4. ^ Lee, K., Yeats, P., Smith, J., Pertie, B., & Milligan, T. G. (2002). Environmental effects and remediation of contaminants in Sydney Harbour, NS. TSRI Project Number 93. Nova Scotia Science, 2425, vii. 108 pp.
  5. ^ Walker, T.R., MacAskill , D., Rushton, T., Thalheimer, A.H., Weaver, P. (2013) Monitoring effects of remediation on natural sediment recovery in Sydney Harbour, Nova Scotia. Environmental Monitoring and Assessment. DOI: 10.1007/s10661-013-3157-8.

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