A new study has found that chemical emissions from oil sands tailings ponds are much higher than official estimates reported in environmental impact
assessments (EIA). This discovery adds to the growing focus on environmental reporting methods in the oil sands.
The study, authored by Abha Parajulee and Frank Wania at the University of Toronto, and published in February in the Proceedings of the National
Academy of Sciences, discovered that indirect sources of emissions to air were greatly underestimated. The report identifies the evaporation of
tailings ponds that store residual fluids from oil sands extraction as important emitters of polycyclic aromatic hydrocarbons (PAH) – including carcinogens phenanthrene, pyrene, and benzo(a)pyrene.
The authors of the study argue this discrepancy requires a major overhaul of the “methodology used to estimate PAH emissions from different sources in
environmental impact assessments.” Modelling of tailings pond evaporation is not currently required for EIAs because the National Pollutant Release
Inventory (NPRI) indicates they are “contained within managed disposal sites and are not being released directly into the environment.”
This claim is obviously under dispute with these new results, which have reportedly caused a stir at the Joint Canada-Alberta Implementation Plan for
Oil Sands Monitoring (JOSM) program. “We have heard from government scientists working with the program who say the work has generated a lot of
attention and interest amongst their colleagues and superiors,” said Parajulee, a PhD candidate who spent much of the last year in the Athabasca oil
sands region collecting samples and conducting the study.
The study began as a term project for a modelling course, with Parajulee looking to see how PAHs travelled through the environment. “We had no idea we
would come to the findings that we did,” she said. “Things started to get more interesting when we found that the modelled concentrations didn’t quite
match up to measured concentrations, and so we decided to see what would happen if we tried to account for the huge numbers [of PAHs] reported as
‘disposal’ to tailings areas in the NPRI.”
To flesh out a clearer picture of the total emissions being released, Parajulee used a multimedia fate model, known as the Coastal Zone Model for
Persistent Organic Pollutants (CoZMo-POP) which accounts for and offers a more complex and holistic view of chemical interactions in the environment.
Developed by Wania and his colleagues over 15 years, and driven by JOSM and Parajulee’s samples from the soil, water, air and foliage of the Athabasca
region, the model uses algorithms to detail the transport of chemicals between elements of the environment, such as the surface of the tailings pond
and the air with which it is in contact.
The results showed a discrepancy of “two to three orders of magnitude” between Parajulee’s measured PAH levels and estimates in official EIA sources.
“It is on some level understandable that these models are not used so much,” said Parajulee, indicating the time it took to complete her study would
add extra work to the EIA process.
Nevertheless, environmental impact assessments for Teck’s Frontier Oil Sands mine project in 2011, the Shell Jackpine mine in 2012, and the Shell
Pierre River mine in 2013 included similar models “to evaluate the contribution of atmospheric deposition to snowmelt and assess the fate of PAHs from
the snowmelt in the aquatic system using different development scenarios,” according to Nikki Booth, a spokesperson for Alberta Environment and
Sustainable Resource Development (ESRD). At the moment, requirements for companies to use the CoZMo-POP model are project-dependent. “The actual
process for determining the appropriate model may be specific to its application and is determined on a case-by-case basis,” she said.
Some oil sands operations have begun additional work to better understand PAH emissions from tailings ponds. “Some mining companies are performing
fugitive emissions surveys, under the direction of the Alberta government, to try and monitor the actual level of these emissions from tailings ponds,”
said Andrew Read, a chemical engineer and technical and policy analyst at the Pembina Institute. He said the frequency of these tests increased in
2013. Since this is a new area of research though, Read explained, there is no indication at this point how or when the data collected will
consistently inform the decision-making of Alberta and federal government regulators.
“There are major efforts underway through JOSM to develop improved models, a better understanding of pathways, and a better understanding of the limits
of existing data,” said Geraldine Anderson, a Canadian Association of Petroleum Producers spokesperson, without addressing the specific impact of
At the moment, environmental assessment requirements are in flux. “The modelling approaches used in the recent EIAs are still under development,” said
Booth, “and will be validated using ESRD’s recent snowpack surveys conducted in the oil sands area.”
As methods to estimate emissions from tailings pond evaporation become available or are improved, “companies are expected to use these methods in
completing their [pollutant inventory] reports,” said Environment Canada spokesperson Mark Johnson. Funding is now flowing from Environment Canada for
more modelling work from the University of Toronto to follow up on its recent findings, he added.
Parajulee is readying her next project. Using multimedia fate models, she will assess PAH exposure to the out-of-province population working in the oil
sands and to the region’s aboriginal communities. “These models,” she said, “could probably be used more often than they are.”
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