Baytex Energy Corp. says a damaged vent valve likely helped trigger explosions July 27 that blew the tops off two huge oil storage tanks at a shut-in well site near Nampa, south of Peace River.

In an update to area residents, Calgary-based Baytex explained that "by discontinuing operations to certain components of the facility, certain safeguards that should have continued to operate were shut down.

"This failure allowed an explosive combination of gas and air to form in the production tanks where the mixture was ignited by the high-pressure flare."

The site had been shut-in, meaning it was not producing and the well had been "valved off," Andrew Loosley, director of stakeholder and community relations for Baytex told CBC News in a previous interview following the explosions.

In its update to residents, dated Sept. 14, Baytex said that despite being shut-in, there was on-site an "operating pipeline system that remained operational."

The update explained that a vent valve, intended to allow gas to flow out of the production tanks while preventing air from flowing in, had been damaged at some point prior to the incident.

"This damage could have allowed air to travel from the high-pressure flare to the production tanks," the updatesaid.

Both the high-pressure flare system and a low-pressure flare system were designed "such that they are always energized and burning when operational," the update says. "At the time of the incident, the high-pressure flare system was operational, providing an ignition source."

A mixture of air and gas formed inside the production tanks and was ignited by the high-pressure flare. It travelled through the low-pressure flare and vapour recovery system into the production tanks.

Explosions caused tremors

The resulting explosions were strong enough to blow the tops off the two 1,000-barrel production tanks.

There were no injuries, but the blasts frightened a resident living just a few hundred metres away, who was watching early morning television inside his trailer at the time.

Tremors were felt by residents living three kilometres from the site, according to the fire chief of the Municipal district of Smoky River. He and 16 members of the volunteer fire department responded to the early morning incident and quickly put out the fire.

MD of Smoky River fire chief Marcel Maure says he's satisfied another explosion won't happen. (MD of Smoky River)

"It was a little bit of human error, little bit of malfunction error," said fire chief Marcel Maure,

Maure said he was briefed by Baytex on the source of the problem and is satisfied with the explanation.

"I'm sure they've gone out and checked all their valves, and that we shouldn't have any more problems like this in the future."

Regulator still working with Baytex

Alberta Energy Regulator spokesperson Ryan Bartlett said it has not yet determined if Baytex Energy will face any enforcement or compliance restrictions for the incident.

"We continue to work with Baytex regarding the incident and the site remains shut in," Bartlett said.

Remedial actions ordered by the AER can include a warning letter, suspending a licence, or issuing orders.

Companies can also face fines, prosecution or operational restrictions if regulations are not followed.

There is no indication Baytex was not in full compliance with the regulations at the time of the incident.

Baytex also explained in its letter to residents that it has taken steps to ensure a similar incident doesn't happen again, and its operational procedure for "the shut-in of a well pad facility" is being reviewed.