Four months following the worst coal slurry spill disaster in Alberta’s history, scientists at the University of Alberta are projecting cleanup and restoration efforts are likely to take years, if not a decade, to repair damage to the Athabasca River and its two impacted tributaries.
Dr. Greg Goss, an aquatic toxicologist with the university’s biological sciences department, is one of four scientists reviewing Sherritt International’s remediation and monitoring plans for the Obed Mountain tailings pond spill, which dumped 670,000 cubic metres of coal sediments and contaminants into the Athabasca last fall.
He said the long, cold winter has ensured sediment deposits have remained frozen, giving the company time to prepare for spring thaw, when the plan will be to prevent as much leftover sediment as possible from entering the river system.
“Really what needs to happen is we need to let the snow melt, capture all the stuff, prevent as much as we can from going into the river at this point, and then take a look at the site under the light of the spring and say really where we’re at,” Goss told The Journal.
While there has already been concern about the delay in getting a remediation plan in place, Goss said the public must be aware that there is no quick fix to an incident of such magnitude.
“This is a long-term process. This is going to take years, perhaps even a decade, to resolve because there are some long-term impacts, potentially with fish habitat in the region, which is I think the main scar that’s going to be left on the landscape,” Goss said.
“You had a wall of water rush down and essentially knock down trees in a 50-metre wide swath for 5 km. That’s not a small impact, and that’s going to take some time to remediate…The term says remediation plan, but in reality, it is a restoration plan.”
No risk to drinking water
Monitoring efforts are going to focus on the heavy metal and hydrocarbon contaminants, which included mercury, arsenic and cancer-causing PAHs, attached to the sediments to determine where they are now and where they are traveling.
Though there are plans in the works for long-term monitoring, Goss said in the short-term, there remains no concern with respect to filtered drinking water from the Athabasca.
He said scientists are still trying to work out the potential impacts on the Athabasca Delta near Fort Chipewyan, but estimated the risks would be relatively low from this spill.
“The total amount of sediment that’s present and carried, the stuff coming out of the lowbed, is going to be a tiny fraction of the total amount of sediment, and metals and everything else (in the river),” Goss said. “But the coal fines are going to be different; in fact, the coal fines are probably floating as opposed to settling out, and are probably out on the lake (Athabasca) and the surface water and floating out.”
Plans for long-term metals monitoring will depend on whether or not contaminant levels are detectable in significant amounts in the area.
“If the levels suggest that there’s almost nothing or non-detectable levels emanating out of the Obed mine in that region, they’ve caught most of the stuff in the upper regions, then probably not, but again that’s up to (Alberta Environment) and the coal mine,” Goss said.
Plans still being submitted
Goss and the other scientists were contracted by the Alberta government to provide independent analysis on four plans required under the Environmental Protection Order given to Sherritt following the spill, which include plans for immediate sampling and monitoring, impact assessment, long-term sampling and monitoring, and wildlife mitigation.
So far, only the immediate and short-term monitoring plan is available online on the government’s website, though an Alberta Environment spokesperson told The Journal all the plans had been submitted, except for Sherritt’s final long-term remediation plan, due May 16, 2014.
Goss said Sherritt has essentially accepted all of the scientists’ recommendations for the short-term, which is positive.
Sediment removal priority for spring thaw
Sherritt’s plans include a variety of measures intended to prevent further deposition of the coal sediments into the river while also cleaning up the Apetowun and Plante Creeks, which were hit first by the massive spill.
Measures include installing sediment traps to catch and divert sediments to pools where they can be removed by vac-trucks. Pockets of sediments will be removed by hand and the contaminated trees and rocks, downed by the gush of coal slurry, will be used to prevent further erosion and deposition during the cleanup, along with fences, bales, bags, jute mesh nets and soil stabilizers (flocculants).
For now, solids removal is only planned for the immediate creeks and the site where Plante Creek meets the river, and not for the Athabasca itself.
Fish habitat will be further assessed following spring melt and on a seasonal basis, with a long-term fish monitoring program to be developed with regulators following further sampling and habitat mapping.