PotashCorp has revealed a number of leaks have been found in a liner beneath a salt-water tailings pond at the former Cassidy Lake mine site, near Norton.

The Cassidy Lake mine stopped operation in 1997 when it flooded. A 70-acre tailings pile and brine pond with a liner underneath remained. That liner, which dates from the 1980s, has been compromised, allowing brine — essentially salt water — to drain into the ground beneath.

PotashCorp N.B. sign

PotashCorp officials say the leaking salt water from the tailings pile will have to be managed for a decade or more. (CBC)

The leaks, first detected in 2008, have been patched, but there could be others that haven't yet been found, says company president Mark Fracchia.

"The liner is imperfect. We know we've had some tears over the years that we've observed, and some localized pitting or holes that we've addressed. We've patched everything we've been able to see over the years."

The Saskatchewan-based PotashCorp is working with a consultant and has drilled additional wells on the mine property to capture water moving underground. The water is then pumped back into the brine pond and eventually sent by pipeline 34 kilometres to the Bay of Fundy.

Fracchia says the efforts are working.

"It is fully contained and we're confident of that."

Stephanie Merrill, of the New Brunswick Conservation Council's freshwater protection program, isn't convinced.

"Salt water and wells and aquifers certainly don't go together," she said.

"The Department of Environment really needs to step up and be overseeing the cleanup of this site, and to put in place new requirements."

Homes and farms in the Cassidy Lake area depend on wells for their drinking water. Neighbours CBC News spoke to on Wednesday said they were unaware of the brine problem at the mine site.

Fracchia concedes the problem will have to be managed for a decade or more, at least until the tailings pile on the site can be dissolved away by annual spraying from water cannons.

"It'll continue the way it is for the near future," he said.

The liner can only be replaced once the tailings pile has dissolved, said Fracchia. The pond will remain on the site after that time, he said.