Alberta Premier Rachel Notley says concerns about environmental contamination will delay the return of up to 2,000 evacuees expecting to move back to their homes in fire-damaged Fort McMurray until as late as September.
Re-entering the scarred community is to proceed this week for most residents as previously announced. But Ms. Notley said Monday that more than 500 homes and about a dozen apartment complexes that escaped a wildfire earlier this month in three otherwise heavily damaged neighbourhoods are not safe to be lived in yet.
She said that conclusion was reached with health experts following tests that found ash tainted with toxic heavy metals and carcinogens such dioxins and furans.
"It was determined that the volume of what we've just described was sufficient that those intact homes were not safe until that kind of waste was removed," Ms. Notley said. "It means that people who live in those neighbourhoods should not plan to return permanently on June 4 as originally planned."
The U.S. Geological Survey found ash left after California's home-destroying wildfires in 2007 and 2008 was far more alkaline than ash from wood fires. Mixed with water, the ash was almost as caustic as oven cleaner.
It was also significantly contaminated with metals, some of them toxic. Arsenic, lead, antimony, copper, zinc and chromium were all found at levels exceeding Environmental Protection Agency guidelines.
As well, ash particles from urban-wildfire blazes tended to be smaller and more easily inhaled. Both arsenic and hexavalent chromium – a form of the metal known to cause lung cancer – were more readily taken up by lung fluids than they were in water.
Arrangements will be made for people from the affected homes in Fort McMurray to make a one-time visit.
"We believe it will be possible to arrange for these residents to temporarily return to inspect their residences and retrieve their belongings," Ms. Notley said.
Crews will attempt to stabilize the ash and remaining debris by spraying it with a non-toxic substance called tackifier, which Ms. Notley compared to papier-mâché. Meanwhile, services are slowly being restored in preparation for residents who will return on schedule. Gas stations and grocery stores are being restocked.
"They're working very quickly with those key retail providers," Ms. Notley said. "We are certainly encouraging people to bring up as much of their own stuff as they can."
The Red Cross also announced Monday that it is releasing another $20-million from donations to everyone able to move back.
Returnees are to receive $300 for the first person in a household and $50 for each additional person. The electronic transfer of cash is intended to help with immediate expenses such as buying cleaning supplies and replacing rotten food.
More than $100-million has been donated to the Fort McMurray relief effort. Tuesday is the last day for individual donations to be matched by the federal and Alberta governments.
A provincial state of emergency that has been in effect in the Wood Buffalo municipality since shortly after the fire whipped through the city is to be extended until the end of June to coordinate cleanup and return of residents more easily, Ms. Notley said.
The fire is still burning and covers about 5,800 square kilometres, although it is not expected to grow significantly in coming days due to cooler and wetter weather conditions. About 300 South African firefighters have arrived to help, which brings the number battling the blaze to 2,000.