Officials in charge of cleaning up Nova Scotia's largest environmental contamination site at Boat Harbour in Pictou County recently had their first glimpse of the accumulated pulp mill sediment sitting on the bottom of the sprawling 140-hectare wastewater lagoon.

The latest estimates put the cleanup of the site at $133 million.

The sediments, which contain a host of chemicals, were pushed to the surface as part of a test project that eased fears the contaminants would react with the air and stink.

"What is a bit surprising to us is even though we are here and we've got a slight breeze coming off, there's no dust and no smell," said Ken Swain, manager of the Boat Harbour cleanup project. "Even if we go up there and grab a handful of it, it doesn't have smell, which is reassuring to us."

However odour may still be a concern as the cleanup progresses. The 11-hectare cove that will be drained in a pilot project over the next year will reveal more about the larger cleanup.

Contaminants pushed to surface

Boat Harbour is owned by the Nova Scotia government.

It is a collection of settling ponds, basins and coves that receive tens of millions of litres of toxic wastewater piped daily from the nearby Northern Pulp mill at Abercrombie Point.

Until now, no one was certain how the sediment that has settled to the bottom of Boat Harbour over the past 50 years would react when exposed to the air.

The contaminants include zinc, cadmium, mercury and small amounts of organic pollutants like dioxins and furans.

Northern Pulp must have a new waste treatment facility by 2020. (CBC)

This spring, a 240-metre impermeable earth barrier was built to isolate one of the coves as part of a pilot project to test technical options.

As the fill was dumped in to build the barrier, it created what is known as a mud wave, exposing the original harbour bottom — shells and all from when it was a tidal estuary — and the contaminated sediment accumulated from five decades of pulp mill effluent.

"We need to keep on top of it, but we're thinking we can manage it," said Swain.

$133M and counting

Dealing with odour is just one element in the massive cleanup, which will involve draining the coves and basins, dredging the sediment and removing the contaminated material.

After that, a dam separating the lagoon from the Northumberland Strait will be removed and the entire area will be returned to a tidal estuary and turned over to the Pictou Landing First Nation.

The cleanup will begin in earnest in 2020, when Northern Pulp must have a new waste treatment facility.

Tens of millions of litres of toxic wastewater are piped daily from the nearby Northern Pulp mill at Abercrombie Point. (Jeorge Sadi/CBC)

There are an estimated 350,000 cubic metres of contaminated material.

Cost forecasts have risen steadily since the project was first announced, from $52 million in 2015 to $88 million in 2016 and now to $133 million.

"As we know more, we're understanding better the volumes of contamination, areas we have to deal with and the means we will access various parts of Boat Harbour. We will need more roads," said Swain.

$6.7M project design contract awarded

In May, the province awarded a $6.7-million contract to GHD, an international consulting firm, to come up with a detailed plan for the cleanup.

Formerly known as Conestoga-Rovers & Associates, the consultants worked with Swain when he helped manage the $400-million cleanup of the Sydney Tar Ponds.

The federal government contributed $280 million toward the Sydney Tar Ponds cleanup.

The former tidal estuary has been receiving wastewater 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. (Steve Lawrence/CBC)

Nova Scotia federal cabinet minister Scott Brison said he was not prepared to answer a question about federal funding for Boat Harbour, when asked by CBC News.

Local Liberal MP Sean Fraser did not respond to a request from CBC News.

Ken Swain said talks with Ottawa are "preliminary."

First Nations 'optimistic'

Boat Harbour has been a long-standing grievance for the Pictou Landing band. The treatment system is literally in their backyard.

A burst effluent pipe in June 2014 leaked 47 million litres of toxic wastewater and triggered a protest that resulted in a commitment from the McNeil government to act.

In 2015, the Liberals passed the Boat Harbour Act mandating the closure of the facility.

"We are looking to find a solution to remediate this," said Chief Andrea Paul. "That is significant in itself. We've never reached this point before."

Replacement facility estimated at $100M

Northern Pulp has a lease with the provincial government to operate Boat Harbour until 2030.

It has estimated that building a new wastewater treatment facility would cost $100 million.

The sides are negotiating next steps.

General manager Bruce Chapman said it's likely a new facility will be built on its property close to the mill.

He said a precise design and costing study is underway right now and will be completed in the next few months.

Bruce Chapman of Northern Pulp said it's likely a new facility will be built on its property close to the mill. (CBC)

"Both the province and Northern Pulp are committed to meet the schedule. We have skipped a step of the plus or minus 30 per cent capital estimate [study] and gone straight to the plus or minus 10 per cent. Both sides are working very hard to make the deadline," he said.

Although the mill's Indonesian owners have not yet approved the project, Chapman said the company is committed to its Nova Scotia operation.

"We are committed for the long term. We will have a treatment plant and we will be running here for many years to come. That is the plan," he said.