Hydrogen sulfide leak at Brantford high school

Levels of hydrogen sulfide gas are being monitored at Brantford Collegiate Institute after a leak in their geothermal system.

According to a statement sent to parents and shared online, it was detected in July during construction at the Brant Avenue high school.

“Over the summer, work was scheduled to repair the school’s geothermal system, located in the sports field at the rear of the school. Low levels of hydrogen sulfide gas were detected during this work,” BCI Principal Michael Degroote said.

Crews repairing Brantford Collegiate Institute’s geothermal system on Sept. 20, 2024. (Krista Sharpe/CTV News)

“At that point we, the Grand Erie District School Board, called a number of folks, including the Ministry of the Environment, public health, Brantford Fire, and we also brought on an environmental consultant,” explained Ryan Strang, the school board’s senior manager of communications and community relations.

Both said there are no immediate health risks to staff, students or the community.

What is hydrogen sulphide?

Hydrogen sulphide is a colourless gas that occurs naturally in sewers, manure pits and well water, in addition to oil and gas wells.

It’s often recognized by its “rotten egg” smell.

“Even in very, very low concentrations humans can smell it, but that doesn’t mean that it’s dangerous,” said James Craig, an environmental engineering professor at the University of Waterloo. “It is not a threat until it’s at larger concentrations.”

At that level, hydrogen sulphide can also be flammable and toxic.

“At high levels of exposure (which is between 750 to 1,000 parts per million), hydrogen sulfide can damage your nervous system or other organs and tissues in your body,” explained the Brant County Health Unit.

Lower concentrations, from 10 to 100 parts per million, can cause irritation to the eyes, nose or throat, difficulty breathing in people with asthma, headaches, poor memory, tiredness and balance problems.

Concentrations at BCI

On the day the gas was detected, in-ground readings came back at 5.0 parts per million.

Those numbers have since dropped.

“The levels of hydrogen sulphide currently being detected below ground are, as of September 19, 3.7 parts per million, which is not considered hazardous,” the health unit said. “Levels above 10 parts per million would be deemed hazardous.”

Brantford Collegiate Institute on Sept. 20, 2024. (Krista Sharpe/CTV News)

The BCHU added that no hydrogen sulphide has been detected above ground and on-site environmental contractors are measuring the levels twice a day, at multiple locations on school property.

What’s next?

Starting on Sept. 20, a small portion of the geothermal system is being decommissioned to eliminate future risks. There will be real-time monitoring of hydrogen sulfide levels during this period.

Officials said they expect minimal disruption during decommissioning and no significant impact in day-to-day operations at the school.

The grass field will be replaced after the work is done.

Alternate arrangements for outdoor activities will be available nearby, the school said, based on availability.