First details of tar ponds cleanup strategies released

By Tanya Collier Macdonald
Cape Breton Post
Thurs., Jan. 6, 2005

Cape Bretoners have received their first detailed look at proposed cleanup strategies for the tar ponds and coke ovens sites.

An expression of interest was advertised by the provincial government Wednesday on the tenders Web site. The Department of Transportation and Public Works is calling for an engineering firm interested in monitoring the planned remediation effort. In that public tender, a project description summary reveals some specifies on the planned project, expected to cost up to $400 million.

It reports that incineration is the contaminated destruction technology selected for both the coke ovens and tar pond sites remediation projects. "PAH contaminated sediment from coke ovens brook, contaminated material from the tar cell at the former Domtar site, and PCB contaminated sediment greater than 50 ppm from the north and south ponds, will be incinerated."

The tender states the preferred location of the incinerator has not been selected, but adds it won't be located at either the coke ovens or tar ponds sites due to restrictions. "The incinerator will be used as a temporary incinerator, it will roll to the site on two to five flatbed trailers, and be set up," the tender details. "The facility will then undergo a commissioning period during which the operating and control systems will be calibrated for the waste feed. Operation of the incinerator will be governed by the operating procedure established during calibration. The incinerator will be operated for a period of approximately five years at 15 tonnes per hour, 24 hours a day, seven days a week for 250 days per year. The incinerator and ancillary facilities will occupy a land area of approximately two to five hectares."

It also explains that once contaminated material has been excavated, it will be transferred from its current location to an incinerator staging area. Rail cars or trucks are the options listed as transport methods.

A comprehensive monitoring program will be developed and implemented to ensure the incinerator is operating within regulatory requirements, it continues.

Wastewater treatment is also required during the cleanup and will serve as a long-term function for groundwater treatment after the remediation projects have been completed. "Treatment will be required for contaminated wastewater produced at the incinerator site, the sediment dewatering area, truck and equipment decontamination pads, from personnel decontamination areas, and others," the tender continues. "Treatment is also required for contaminated groundwater and surface water at the coke oven site."

The tender states that bioremediation and capping is the selected treatment technologies for the coke ovens work. However, exposed sediment in the former coke ovens brook bed will be transferred to the incinerator.

In addition, contaminated soils in the tar cell will be excavated to a depth of about two metres below grade. An enclosure will be constructed during excavation to prevent harmful discharges to the environment and to provide air treatment.

Vertical cut off walls will be constructed on the coke ovens site to control the movement of clean and contaminated groundwater and surface water.

The wall will be installed north and south of the area to prevent influx of clean groundwater. They'll also be installed to the west to prevent the movement of contaminants from the Sysco site and walls will be installed to prevent the movement of coal tar from the Sysco site into Coke Ovens brook. Landfarming for parts of the co-ke ovens sites is also planned. Oxygen, nutrients and water will be applied to treat the top half-metre of hydrocarbon impacted soil at rates most beneficial for biological degradation of organic contaminants.

If it's determined that odours and dust production during the landfarming could be a problem, the need for vapour treatment facilities will be investigated.

The tender confirms that incineration, solidification, stabilization and capping are selected as the treatment technologies for the tar, ponds portion of the cleanup.

The containment system will consist of impervious vertical walls installed at various locations around the edges of the tar ponds. "Selected PCB contaminated sediment will be dredged and or excavated using a combination of conventional shore and water based technologies," the tenders details.

Impact to the water column will be reduced by installing turbidity control systems. "Sediment removal could work on 12 hours per day, seven days per week for seven to nine months per year. An average dredging rate will vary for a low of 400 to a high of 1,500 tonnes per day."

PAH contaminated sediment within the ponds will be solidified and stabilized in place using a binding agent such as Portland cement. A surface cap will then be constructed. Additional caps may be necessary for contaminated. sediments that remain.