ATHABASCA — It's graduation time for the two high schools that operate within the borders of Athabasca County, but a fuel leak dating back to before this year's graduates were even born, is still being remediated at the county's public works yard, and is expected to continue for at least another four years, costing the municipality millions.
Before Aspen View Public Schools came to be in 1995, Athabasca County ran the schools and took care of student transportation which required large underground gas tanks to be used for more than 20 years to fuel the then Athabasca County school bus fleet. The tanks had been leaking before they were removed between 1993 and 1996, and now cleaning it up has cost the county almost $2 million.
Athabasca County's Public Works Committee was informed June 15 by Sean Nicoll of Associated Engineering it will likely take another four years to finish the remediation process on the site.
“Prior to 1993, the site did contain underground fuel tanks,” Nicoll said. “Between ‘93 and ‘96 the fuel tanks and the fuel system were decommissioned and removed from site and based off the ... consultant's report who did the decommissioning of the tank removal, it was identified the hydrocarbon contamination remained on the site even after the tanks were pulled.”
He explained that because gasoline is lighter than water it floats on the surface and the goal of the remediation is to meet Alberta Environment and Parks guidelines, but the process was further impeded when higher-than-expected levels were detected in 2020.
“The sudden reappearance of (hydrocarbons) basically means that we haven't got rid of that source material and it's still present within the site,” he said. “And unfortunately, due to the rebound of free products observed last year, we still have a number of years left before we're done.”
Coun. Travais Johnson asked if any of the contamination could be coming from the bulk tanks at McEwen’s Fuel and Fertilizer located on the north side of the yard.
“We have monitoring wells upstream of us and we're not seeing any contamination coming from that source,” Nicoll said. “The site is in essence circled with groundwater monitoring wells and we're not seeing anything come from offsite.”
He added that as long as the contamination doesn’t spread outside the borders of the property – it's moving southwest toward Highway 55 south of the property – they can take a slower approach to cleaning up the site.
“We’re trying to prevent our contamination going offsite and onto Alberta Transportation’s property because as soon as that happens – Alberta Environment has allowed us to basically set our own course – (but) as soon as we start impacting somebody else’s property it becomes a lot more stringent.”
The whole process started in 2003 when Athabasca County wanted to develop the area and requested a review of the original report leading to environmental investigations between 2003 and 2007 showing the edge of the leak, or plume as it’s called, had not extended past the property line and a plan was developed for multi-phase extraction (MPE) using several wells to install vacuum lines to draw up the gasoline.
“The unit would separate out the liquid from the air portion (and) the vapour portion of it would go through a blower and then into an off-gas treatment unit,” said Nicoll. “And for a number of years at the start – between 2007 and 2009 – the vapour was actually flared off; the concentrations were high enough that we could flare it and then shortly after 2009 that system was decommissioned.”
In 2010, a hydraulic capture well was installed on the southwest corner of the property to pull the groundwater, and the contamination with it, for capture and prevent it from moving offsite.
“At the end of 2019, the MPE system was removed due to a reduction in recovered hydrocarbons from the site and the fact that we hadn't seen free product within the site for approximately six years,” he said. “So, at the end of 2019 … we were pretty confident we were getting at the source material.”
In 2020, the MPE system was replaced with a water treatment system to treat the water before being discharged into the sanitary system, but samples from August of that year showed higher levels than had been recorded in six years.
“Between 2007 and 2019 about 18,000 litres of gasoline, or hydrocarbons, were removed from the site and 300 litres of free phase product was removed,” said Nicoll. “In 2020, the water treatment system treated and discharged to sanitary about 434,000 litres of groundwater.”
Nicoll told the committee current processes will stay in place and enhanced bio-remediation will be added – the injection of oxidizers and micronutrients allowing microbes in the soil to actively consume the hydrocarbons.
“Unfortunately, bio-remediation can only really sort of eat at the edges of the plume, it can't deal with the source,” he said. “The concentrations are too high, and the microbes aren't going to be able to eat that down.”
Between 2017 and 2020 the cost has been $1.8 million and Nicoll said the higher concentrations found last year means it will be at least four more before remediation is complete, noting digging out the area is cost prohibitive.
“So, as of 2019, we were kind of walking our way out of the site in about four years,” Nicoll said. “Unfortunately, in 2020, it now looks like there’s the potential for more, but I'm still optimistic that four years is sort of the end.”
Coun. Kevin Haines, who chairs the committee, said in an interview June 19 the problem is no one’s fault, meaning no matter who pays for it the taxpayers are on the hook but it is another blow to the Athabasca County budget and the amount of time it is taking is frustrating.
“It's just more money that we've got to come up with along with everything else we're coming up with because we're getting so many downloads (from the provincial government) here the last how many years,” he said.
“When I (was elected) 14 years ago it was, 'We figure we have about two more years, it's cost us a lot of money, but two more years and we should be able to have this cleaned up.’ Well, here we are 14 years later.”
