Alberta’s Liberal leader says the province needs to go after the former owner of a wood preserving plant to pay for the cleanup of lands west of Calgary’s downtown contaminated with nearly two million litres of toxic creosote.

While taxpayers funded a $12.5 million containment wall that was constructed two decades ago to keep the carcinogenic liquid from oozing into the Bow River, David Swann said he’s worried the underground plume remains a threat to the environment and to residents across the river in his Mountainview riding whose groundwater is laced with levels of naphthalene that exceed safe guidelines.

“It’s not only the right thing to do,” said Swann “but it sends an important message to companies in Alberta that they can’t walk on their liabilities.”

For nearly half of the four decades the plant operated on a 15-hectare property between 14th Street and Crowchild Trail prior to its closure in 1962, it was owned and operated by a predecessor of Domtar Corporation, the continent’s largest paper manufacturer.

Officials with Alberta Environment and Parks have said they are prevented now from pursuing the Montreal-based firm to clean up the site because it no longer has a corporate presence in the province.

But legal experts consulted by the Herald say previous rulings by the country’s top courts suggest there’s nothing to stop the recently-elected NDP government from demanding Domtar pay for some or all of the cost of remediating or removing an estimated 25,000 dump truck loads of hazardous waste.

Environment Minister Shannon Phillips declined to be interviewed, but her press secretary said department officials were meeting their counterparts at Alberta Justice to answer questions from the Herald about whether further remediation is required at the site and whether it would pursue Domtar for some or all of the costs.

“We’re having a very serious look at the issues that have been raised,” Laura Tupper said.

“This is a file that requires in-depth analysis, clearly, to determine the next step moving forward.”

The site is now owned by the city and is the proposed new home for an arena and stadium complex that would house Calgary’s professional hockey and football teams.

Initial discussions about redeveloping the property have focused on who will cover the remediation costs that some estimates have pegged at as much as $300 million.

Recent studies have shown the containment wall installed in the 1990s to keep contaminants out of the river is not working as designed and that tainted water is likely moving over, around, and under the wall, seeping into the river.

Levels of naphthalene downstream of the site have spiked in recent years, although scientists have said it’s “unlikely” they pose a risk to fish and other aquatic life.

While Alberta officials have expressed reluctance to order Domtar to remediate the site because they did not break any laws of the day, B.C. is forcing the company to clean up a former wood preserving plant that was also closed and sold in the 1960s.

South of the border, state and federal environmental protection agencies have required Domtar to pay $13. 5 million to remediate two contaminated sites, including the cleanup of a former coal tar refinery in Duluth, Minnesota that the company closed in 1948 and sold several years later.

Domtar, which had net earnings last year of $364 million on sales of $5.6 billion, says in its most recent financial filings that it has also been notified it may be responsible for an undisclosed number of other hazardous waste sites in which no formal proceedings have yet been started.

The company has set aside $60 million to cover future environmental remediation costs.

Campaigning in Calgary this week, Premier Rachel Notley said the NDP believes companies, not taxpayers, should have to clean up contaminated sites like the former Domtar plant.

“What we’re dealing with now is a past failure of government to aggressively pursue the polluter pay principle,” Notley told reporters.

But Alberta Party leader Greg Clark said he’s concerned the bureaucracy, not elected politicians, are setting the new provincial government’s priorities for handling of the former plant site.

“I expect the minister to show leadership on this issue” said Clark, “and aggressively pursue any and all avenues available to make Domtar pay to clean up the mess they made.”