The manager of the Boat Harbour cleanup project in Pictou County says it will take a couple of years before it’s known if the $52 million set aside will be enough to remediate decades of primarily pulp mill waste and other industrial residues.

Nova Scotia’s Liberal government has pledged to shut down the government-owned Boat Harbour treatment facility in 2020. It’s a promise made to the Pictou Landing First Nation, which sits next to the harbour.

“It’s certainly a long-standing environmental scar. It’s important that situation is rectified,” says project manager Ken Swain, who also oversaw the $400-million Sydney tar ponds cleanup.

He’s been hired on a $150,000 annual contract to oversee planning for the Boat Harbour remediation.

“It’s entirely manageable. It’s realistic. It’s achievable,” he says.

100 swimming pools worth of contaminants

The former tidal estuary has been receiving waste water from the nearby Northern Pulp mill since the late 1960s and has now accumulated enough contaminants, when dried, to fill about 100 Olympic-sized swimming pools.

Boat Harbour contains the remnants of decades of pulp mill effluent and some other industrial residues discharged into the area.

Today, the contaminants are resting on the bottom of Boat Harbour in a fluffy layer from five centimetres to 35 centimetres deep. The chemical layer includes zinc, cadmium, mercury and small amount of dioxins and furans.

While confident the project will return Boat Harbour to its pre-industrial state as a tidal estuary, Swain says it is too early to tell what it will cost to complete the job.

“Until we know how the material behaves when it is de-watered, until we understand what technologies will be able to do to reduce the volumes of that material, we won’t have a definitive cost estimate,” he says.

“It’s probably going to be another couple of years before we can refine that estimate. Right now, we know $52 million is our best guess.”

The plan

The plan is to drain Boat Harbour once effluent stops flowing in 2020, scrape off the contaminants — which become jelly-like when dried — and put them in a secure landfill.

The landfill has not been identified, although the province already owns one adjacent to the settling ponds at Boat Harbour.

The three coves in the harbour will be dammed off, either with steel sheet pilings or earthen beams. There will be tests of various technologies to reduce the volume of material, including mechanical pressing.

“It is critical that we do those large-scale pilots,” Swain says.

“We’ll have [a] better idea how the material compresses and understand what volumes we’re dealing with and other practical things like managing odour and the best mechanisms for transporting it.”

Not the tar ponds

The decade-long Sydney tar ponds project capped contaminated material, mostly coal tar, with a solidified mixture which included the contaminants themselves and cement.

That won’t work at Boat Harbour, Swain says. It is currently dammed from the Northumberland Strait. When the dam and causeway barrier is removed, he says the tides would “destroy your cap in a short period of time.”

Meanwhile the province continues to negotiate with Northern Pulp over what will replace the treatment facility for its effluent and where it will go.

The company has said the 2020 deadline is unrealistic, claiming the mandatory environmental assessment alone will take two and half years.

“We don’t think it’s going to take that much time,” says Swain. “We do know the time line for construction and commissioning of a replacement facility is tight. That’s one of the drivers.”

The Pictou Landing First Nation said earlier this year, its studies show construction will take two seasons.

It is likely the next outfall, where the treated discharged water exits, will be into deeper water, Swain says.

“There will be no more effluent flowing into Boat Harbour and the outfall will be somewhere else.”