Gas well repair work suspended

Efforts to cap a problem gas well in Silver Hill have been suspended due to excessive groundwater discharge. File photo

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It’s back to the drawing board for Norfolk County and its effort to cap a rogue gas well in Silver Hill.

Contractors have spent the past several months attempting to drill a relief well in the hazard zone off Forestry Farm Road immediately north of McDowell Road. The goal was to drill a monitoring well so geoscientists could study the hydrology of the affected area.

However, Norfolk County has reported that this is proving impossible because the water table in the area is “overcharged,” providing a steady flow of water to the surface from the underlying aquifer.

The defeat comes before the remediation plan, which was drawn up by researchers at the University of Waterloo and the engineering firm Geofirma, got off the ground.

Phase 2 involved using data from the monitoring well to design a relief well that would control the flow of water to the surface. The third phase involved construction of an on-site treatment plant to scrub toxic hydrogen sulphide compounds from the groundwater discharge.

“The area is being secured with permanent fencing for public safety,” the county said in a news release, adding work is on hold while the associated parties come up with another approach.

The work on Forestry Farm Road is complicated by wetland surroundings. Research indicates the vent beneath the surface is irregular in shape and won’t lend itself to a simple plug.

The uncontrolled release of toxic gas has been a problem in Silver Hill since the Ministry of Natural Resources capped a natural gas vent along Big Creek on North Walsingham Road 10 several years ago.

Ever since, toxic gas has leaked from abandoned wells nearby in what authorities describe as a “whack-a-mole” effect. No sooner is one problem well capped than toxic gas is detected nearby from another abandoned gas well. Mayor Kristal Chopp has described the situation as “Norfolk’s Chernobyl.”

Experts from the University of Waterloo told Norfolk council last year that capping the vent along Big Creek has elevated the water table in Silver Hill, allowing groundwater to combine with sulphur deposits near the surface. Had it been successful, the strategy on Forestry Farm Road would’ve lowered the water table and ended this toxic interaction.

As it stands, homes in the area have been fitted with detectors to monitor ambient hydrogen sulphide levels, which fluctuate depending on the forces at work beneath the ground.

No studies have been done on the long-term effects of hydrogen sulphide exposure at any level. However, immediate symptoms include eye, nose and throat irritation and headache. Anyone experiencing these symptoms is advised to see a doctor.

Hydrogen sulphide smells like rotten eggs. Not only is it poisonous, it is flammable and corrosive. The rapid discolouration of metal surfaces is an early indication of hydrogen sulphide’s presence.

The Ministry of Natural Resources has put up money in recent years to cap problem wells in Silver Hill. The ministry partially funded the work that has been suspended on Forestry Farm Road.

 

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