Contractors drilling a monitoring well near the APEC 2 site in Wheatley struck a pocket of hydrogen sulphide gas 85 feet below the surface at 11:05 am yesterday morning.
Safety measures worked as designed and the site was evacuated and there were no injuries. A loud hissing noise accompanied the emission which lasted until 11:20 am.
Thomas Kelly, Chatham-Kent’s General Manager of Infrastructure and Engineering Services, said a mobile vent stack system at the site of the well drilling was successfully deployed which allowed the gas to vent into the atmosphere without incident.
Drilling was stopped and the crew moved out of the hot zone after connecting the well to the prepared vent system to dissipate the gas.
Work has since resumed.
Fire and Emergency Services Chief, Chris Case, credited a well-designed and practised safety plan with ensuring the incident was handled successfully.
“As part of our response plan, we have firefighters 24/7 on-site, they are supported by the Wheatley firefighters who were called. We do not use lights/sirens so as not to cause stress to the local community,” he said.
Additional Chief Officers and Medics deployed on standby as the engineering team continued their work.
On-site hazmat and technicians moved in to check that the area was safe while fire crews and technicians began mobile monitoring around the area.
“We were advised that the event had concluded and that apart from the detectors close to the drill site no gas had travelled creating a risk to the community. All response teams were stood down around midday and the engineers have returned to work. I am pleased to advise that the plans, which are practiced and drilled regularly, worked,” he said.
Kelly said the APEC 2 monitoring well is the first of two monitoring wells to be installed. One well will reside inside the investigation area and the second just outside the evacuation zone. These wells will allow the investigation team to obtain groundwater and gas samples to support the chemical modelling work.
Case said the incident demonstrates the unpredictable and potentially dangerous conditions that can occur and supports the cautious approach taken by authorities to only allow access to properties when work is not underway.