How did an Irving station leak so much gas before anyone noticed?

How did a gas station leak tens of thousands of litres of gas into the ground without being immediately detected? 

That question is top of mind for some as cleanup efforts continue at the Murray's Irving and Irving I-24 truck stop on the outskirts of Woodstock.

Since mid-December, vacuum trucks have been working around the clock at the Beardsley Road site to clean up what could total more than 100,000 litres of diesel fuel from a cracked pipe leading to an underground storage tank. 

But how such a large amount of fuel was able to leak into the environment without being immediately detected is unclear.

According to documents obtained by CBC News through a right-to-information request, the leak wasn't noticed until contaminants were detected in the well water of a Tim Hortons restaurant across the parking lot.

This led to the closure of both the restaurant and the Irving station while cleanup crews responded. 

Irving Oil Ltd. has not responded to requests from CBC about how the leak went undetected. Gas stations in New Brunswick are required to have systems that detect any leaks.

CBC News asked to speak with someone from the Department of Environment about how it was possible the leak went undetected. No one from the department was made available to answer questions. 

Christine McAllister, owner and operator of the Ripples Little River Convenience, east of Fredericton, says there are "checks and balances" to detect leaks even at small independent gas stations.

"If I have some sort of equipment failure, I have alarms set up," McAllister said. "It's a really awful sound. I've only had it happen a few times for something really simple, but it's really loud and piercing. Worse than a fire alarm."

Her fuel storage tank is an above-ground model, but the regulations for leak detection are the same for underground units, she said.. 

McAllister said there are sensors that detect moisture around the fuel lines at her storage tanks, as well as at the pumps. But even beyond tripping alarm systems, she said, missing fuel would show up in her ledgers. 

"If I'm paying attention to my numbers, it would let me know that something's amiss," McAllister said. 

Every day, she prints off a copy of her fuel sales. Then she goes to the storage tank and measures the fuel amount using a large dipstick.