Work resumes to remove Domtar tank at Sydney coke ovens siteContractors for the Sydney Tar Ponds Agency have restarted work to empty and demolish the Domtar tank at the coke ovens site. Clean Harbors Canada, the demolition contractor, voluntarily stopped work on the project in early June when emissions of naphthalene, a volatile polycyclic aromatic hydrocarbon (PAH), exceeded guidelines established for the site. The compound is best known as the main ingredient in mothballs.
Engineers quickly discovered and fixed two problems with the air handling system in the temporary structure built to enclose the tank during the removal of its contents. The first problem was a faulty switch, intended to control a high-powered fan which draws air from the building through two massive charcoal filters. Secondly, the activated charcoal also needed to be replaced.
The agency and its contractors have also increased air monitoring around the tank. A more sensitive portable monitor, capable of detecting volatile organic compounds (VOCs) in real time at levels as low as 20 parts per billion, is being used.
Technicians from AMEC, the agency's air monitoring contractor, will use the device to run continuous checks upwind and downwind of the tank while the work is being done. They will conduct three checks a day to ensure that the air handling system is working to capacity, and that air pressure inside the building is lower than the pressure outside. Three checks per day will also be done to ensure that the charcoal filters in the building's air-handling system are capturing at least 95% of the VOCs in the building's exhaust.
If any of these checks reveal potential problems, technicians will draw samples for more precise analysis at Sydney's Environmental Services Laboratory, which can provide results in four to six hours. During the first seven days of operations, six monitors at the perimeter of the site will collect 24-hour samples for detailed analysis at Ottawa and Sydney laboratories.
An additional four permanent air monitoring stations located throughout Sydney will continue to draw 24-hour samples for detailed lab analysis once every six days, a schedule that coincides with the National Air Pollution Surveillance network. The results of all air monitoring tests will be posted on the agency's Web site - gov.ns.ca/stpa/ - within 24 hours of being received.
The agency has also established guidelines for prompt notification of the Nova Scotia Department of Environment and Labour, the district medical officer of health, Cape Breton Regional Municipality, Environment Canada, and the public in the event of air quality problems on the site.
The Domtar tank was left behind when the Dominion Tar and Chemical Company abandoned its Sydney operations almost 50 years ago. It contains coal tar oil, a byproduct of coke production widely used in paints, dyes, roofing tar, and driveway sealant. The material is so thick that it must be heated before being screened and pumped into trucks for transport to a licensed disposal facility. The Department of Environment and Labour issued a permit on August 3 to restart the removal operation.