EDMONTON, Canada (From CBC News) -- The Alberta government is making Domtar and other companies clean up the site of a former wood treatment facility in northeast Edmonton that could become a residential development.

The creosote plant in the city's Hermitage neighbourhood operated from 1924 to 1987, and Alberta Environment says the site was partially remediated in 1991.

The department says a numbered company bought the property from Domtar in 2010, and that some contamination was left on the site in an unauthorized landfill and at a former wastewater treatment pond.

It says a berm was also built using contaminated materials, and sampling done by the government found it had "hazardous waste characteristics."

The province is ordering Domtar, Cherokee Canada Inc. and the numbered company to submit an independent sampling and remediation plan for the site of the disposed materials.

Cherokee Canada and the numbered company must also take the same steps for the berm.

"First, we have to determine the nature of the contamination, and that would provide direction for how those sites would need to be remediated," Alberta Environment spokesman Jamie Hanlon said Friday.

"Our concern is that the contamination on those sites be addressed."

In the 1990s, Domtar cleaned up contaminated soil in the backyards of four existing homes next to the former site, but residents were concerned at that time about the lack of action on the site itself.

Creosote is used as a wood preservative and can causing breathing problems and skin irritation. Longer term exposure to creosote has been linked to cancer.

Dr. David Schindler, a water expert at the University of Alberta, said at the time that the arsenic, creosote compounds and pentachlorophenol left in the soil and groundwater when Domtar closed its plant in 1987 were "pretty nasty chemicals."

He said pentachlorophenol is particularly dangerous and has been associated with developmental abnormalities and birth defects.

Alberta Environment said the site is proposed for a residential development.

The department said the current site approval holders have failed to act upon numerous requests since last year for soil sampling results on the berm.

The remedial action plans for the disposal sites are due by July 30. The remediation plan for the berm and any contamination that's found near it is due June 1.

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