Ontario Construction News staff writer
A late-June hydrogen sulfide gas leak in downtown Wheatley — a small community in the Municipality of Chatham-Kent near the north shore of Lake Erie — has renewed concerns over the province’s estimated 27,000 legacy oil and gas wells. Many of these wells are undocumented and improperly sealed, posing hidden risks beneath homes, businesses and public infrastructure.
The odour was first reported behind the Wheatley branch of the Chatham-Kent Public Library on June 26, prompting emergency responders to cordon off the area and evacuate surrounding buildings. Hydrogen sulfide—the same toxic gas responsible for a 2021 explosion that levelled a pub and displaced residents for months—was confirmed in the air the next day.
The latest leak has sparked renewed concern not only about public safety but also about the implications for infrastructure development and land use planning. It also raises questions about the effectiveness of current policies for locating and managing “ghost wells”—abandoned oil and gas wells drilled prior to mandatory reporting, some more than a century old.
Following the 2021 explosion, the Municipality of Chatham-Kent retained 360 Engineering & Environmental Consultants (360 EEC), a Western Canadian firm specializing in subsurface gas migration and well remediation. The company led the original cleanup effort, developing a worst-case response plan that included real-time gas detection, drone-based methane mapping, and detailed emergency zone modeling.
360 EEC located and re-entered the leaking well, installed new casing, and sealed it permanently. But according to the firm, the underlying risk remains. The 2021 explosion was caused by gas from a deep subsurface source that migrated into a shallow water-bearing aquifer—now contaminated with methane and hydrogen sulfide.
“The aquifer essentially acts as a delivery system for gas,” said Adam Derry, Director of Engineering at 360 EEC. “Even though we’ve shut down one known well, others may still be feeding into it. And since the aquifer is already contaminated, there’s no way to treat or remove the gas that’s trapped inside.”
Municipal officials say a new investigation is underway to determine the exact source of the June 2025 leak. A water well is currently being excavated and analyzed, and the municipality is working with Ontario’s Ministry of Natural Resources and Forestry and environmental consultants to assess whether further action is needed.
360 EEC is calling for a province-wide strategy to locate, assess, and decommission legacy wells before they become safety or development liabilities. As it stands, Ontario regulations place the onus on landowners or municipalities, many of whom are unaware of the wells lurking beneath their properties.
“It’s not an emergency because it’s there; it’s an emergency because of what could happen next,” Derry said.
The ongoing risk presents challenges for construction and infrastructure planning. Developers and municipalities may face project delays, permitting complications, or unexpected costs when building in areas where gas migration is possible but poorly mapped. Experts are advocating for better integration of subsurface gas risk modeling into land use planning and construction approvals.
As Chatham-Kent prepares to rebuild Wheatley’s downtown core, the incident underscores the importance of environmental due diligence not just in Wheatley—but across Ontario. The province’s aging and poorly documented energy infrastructure may increasingly intersect with modern construction efforts in unpredictable and costly ways.
