Gas plant poses potential health risk

Okotoks Western Wheel
November 1, 2006 Vol. 32 No. 13

By Pamela Roth
Staff reporter

Members of the Turner Valley Gas Plant Panel received a clear indication as the extent of the contamination at the historical site at a meeting last Thursday.
During the panel’s last meeting in Turner Valley, Dr. David R. Williams of Meridian Environmental Inc. presented a report on risk assessment and risk management of the site to the panel.
In his presentation, Williams outlined the contaminants of concern, which include chromium, copper, mercury and petroleum hydrocarbons that are caused from crude oil, process facilities and products.
According to Williams, hydrocarbons exist in surficial soils around the compressor plant, north and east of the sulphur plant, east of the propane plant and at various underground storage tanks throughout the site. The area of greatest concern was around the buildings.
Elemental mercury was also found in surficial soils around the scrubbing plant, sulphur plant area, propane plant and absorption and shop.
As far as human health is concerned, both the petroleum hydrocarbons and mercury exceeded target levels for daily exposure, however, the risks to aquatic species were found to be acceptable.
“The existing conditions at the site were sufficient to pose a potential health risk,” said Williams. “A risk assessment is really a predictive process. If you can prevent that exposure effectively, you are managing the risks.”
For panel chairman Jim Delay, the information from the risk assessment came as no surprise.
“The panel has always known about the degree of contamination. In general, I don’t think there were any shocks,” said Delay. “While there are still some questions yet to be addressed, it’s believed it was a reasonable risk assessment.”
Since the panel hopes to preserve the site and turn it into a major tourist attraction, Williams suggested a number of steps to reduce the risk of exposure to the contaminants without tearing down the site.
When dealing with the soils impacted by petroleum hydrocarbons, Williams suggested remediating or capping surficial soils, removing sources, limiting public access to stained areas, personal protective equipment and ventilating buildings.
To deal with mercury impacted soils and buildings, similar measures were suggested, including cleaning and sealing floors of buildings and indoor air monitoring.
“If they just manage the contamination, it really doesn’t remove it. It just contains it and controls it,” said Williams. “It’s all they can really do without tearing down the site.”
Although the ultimate objective is shaping the site as a tourist attraction, the panel is currently focused on two things: bringing the site up to code to ensure there are no risks to the public; and dealing with contaminants on the site that might be or have already found their way into the river.
Construction is underway on a $5 million containment wall that is designed to prevent hydrocarbons at the site from entering the Sheep River.
The project, which also includes a groundwater treatment system, consists of a 650-metre erosion and protection wall that will divert ground water to a treatment plant before entering the river.
After taking a look at the construction of the wall, panel member Laurie Hodson, an Okotoks town councillor, is pleased with what he has seen and heard.
“They are proceeding well and I would have to say that all of us are satisfied with the progress,” said Hodson. “There have been a number of studies on this site. We want to keep in mind the ultimate objective.”
Environmental clean up at the site has been ongoing since 1987. Alberta Environment has already removed contaminants such as asbestos, sulphur and mercury as part of a $2.5 million 10-year clean up, however, hydrocarbons and low levels of methyl mercury were found in ground water near the gas plant just last year.
As a result of the findings, the gas plant was closed to the public in November 2005 to allow for the clean up of the site and construction of the containment system.
The panel decided the risk assessment was reasonable and will be looking at each particular contaminant options in detail at their next meeting.