Diesel leak from Irving gas station could be a long-time concern for residents
More than two dozen newly drilled wells likely monitor underground contamination
More than two dozen wellheads have popped up around the Irving Oil gas station in Woodstock that recently leaked more than 174,000 litres of diesel over an undetermined amount of time.
Those wellheads are likely for test wells that are designed to track the flow of fluids underground, including contaminants like diesel.
CBC News tried contacting Irving Oil Ltd. to ask about the purpose of the wells, as well as how long they will be in place and if they indicate a risk to nearby residents. There has been no response.
In fact, no one from Irving Oil has ever replied to calls or emails regarding the significant leak that was first reported in December. That leak resulted in the closure of the company's gas station, restaurant and a neighbouring Tim Hortons.
Since then, vacuum trucks and a cleanup crew have worked non-stop to recapture the spilled diesel fuel, which leaked from a crack in a faulty fill elbow leading to an underground fuel storage tank.
CBC News counted 26 of the newly installed wells. Alongside many of them were drilled-out cores of bedrock and granite. They can be found on the same property as the Irving gas station, as well as on both sides of the nearby Trans-Canada Highway, and across Beardsley Road.
"It's reasonable that there should be some monitoring going on," said Melissa Bunn, a research scientist and hydrologist with Natural Resources Canada in Ontario. "The nice thing about groundwater is that it moves so much slower than surface water, so there can be a bit of time in knowing where it moves."
According to Bunn, diesel fuel is a non-aqueous liquid, or a liquid that does not easily dissolve or mix with water.
Bunn said she's looked at some of the geology records of the leak site and said it's likely that diesel from the leak has been pulled through silt and sand sediments of the ground in that area until it reached the water table resting on bedrock there. She said it's likely that leaked diesel has come to rest on top of that layer of underground water for now.
"This is what's tricky about these liquids that don't quite mix with water is they can hang out for a long time in the soil," said Bunn.
"For non-aqueous liquids like gasoline, diesel, even heavier ones that kind of sink to the bottom of the water column, those all tend to be longer-term issues," she said.
"They don't really flush out of the water system by water flow. They kind of hang in those small little pockets. So it can be a long-term problem where a long-term monitoring network might be needed to understand where it's moving, the concentration that's in the ground water and the risk to the residents."
Bunn warns that when those underground water levels rise and fall, the leaked diesel will start to dissolve into water over time. But in large spill situations, test wells serve as an early detection system for where contamination is flowing underground, she said.
It's unclear how long diesel was leaking from the gas station holding tanks.
The town of Woodstock said it's not involved with the wells but agrees they're likely test wells for monitoring the movement of the diesel underground.
"It's not anything to do with our water," said John Lyons, the town's director of utilities. "I did notice that last Friday night [April 25] I noticed that there's quite a few wellheads there. They look like test wells to me."
Resident fears
Verne and Louise Beers's well sits about 500 metres from one of those new wells and about 700 metres from the leak site across the highway.
They said the contractor Irving hired to deal with the diesel leak, Dillon Consulting Limited, offered to do a single test on their tap water "months ago." It came back clean, but it's done little to calm their fears. They've since paid for a second test themselves, which also returned negative for hydrocarbon contamination.
They worry that someday diesel will show up in their water and their property will be suddenly uninhabitable.
"We're just putting a new roof on this house. Are we wasting our money?" wondered Verne Beers. "As far as paving the driveway and property improvements that aren't crucial, I don't know if we should be spending the money."
The couple would like to have more details about the test results.
"Probably at least a year, maybe two, before I could feel even remotely safe, and it depends on what they're doing over there," said Verne Beers. "If they're still sucking over there, I'm here to tell you I'm probably a little worried over here."
Residents should remain vigilant
Bunn said residents should remain vigilant and continue to keep an eye on their well water, given the proximity to the leak. Knowing how deep your well is, and where along its depth it takes in water is useful because diesel is lighter than water. She said if a well is quite deep and brings in water from a deeper portion, it's less likely to be contaminated by diesel that sits on top of the water table.
Bunn points to New Brunswick's online well log system as a resource concerned homeowners can use to learn about their well's specifications.
She fully understands residents' worries and said if it was her home, she'd want to know where that contamination was spreading.
"In between me and where that spill happened, I would want to know what the results from monitoring are," said Bunn.
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