EnCana Corp. instituted new safety procedures and conducted a risk assessment review at 500 drilling sites ahead of a report issued Thursday by the British Columbia (BC) Oil and Gas Commission (OGC) that said the producer failed to properly execute its emergency response plan following a natural gas leak last November at a shale drilling site.

The sour gas leak occurred because of a “rare piping failure,” EnCana officials said, and “immediately following the incident we initiated a thorough review of our operations, and we continue to consult closely with residents impacted by this incident to address their concerns.

“We know this event was disruptive and caused anxiety for some area residents. This incident is extremely unusual; we’ve never seen this type of well site piping failure in our operations. Safety is a core value at EnCana — for our employees, contractors and residents in the communities where we work. EnCana takes full responsibility for addressing the issues the incident has caused and is taking action to prevent this type of failure from happening again.”

According to the OGC report, EnCana’s Swan well site, where the leak occurred, is near Pouce Coupe, BC, population 700. Last Nov. 22 at around 2:30 a.m. a Pouce Coupe resident smelled what he thought was sewage and did not contact authorities, according to a report issued by the commission.

In the next five hours, the commission said at three other residents reported hearing jet-like roaring sounds and reported smells that were similar to rotten eggs. However, the residents told authorities later that they assumed gas producers were working in the area, and no one notified authorities. At around 8:30 a.m. the commission said a man who was hunting in the area saw a gas cloud and smelled strong odors. He began telling nearby residents to evacuate, and he then called 911. He also called his wife and asked her to notify neighbors to evacuate.

According to records, at 8:38 a.m., the pipe at the Swan well site experienced a “sudden failure,” the report said. At 9:05 a.m. EnCana’s control room received an alarm and five minutes later another alarm confirmed that the well had shut down because hydrogen sulfide (H2S) detection levels were 12.82 parts per million. At 9:35 a.m. the Royal Canadian Mounted Police contacted EnCana officials to inform them of the leak, which was an hour after the 911 call.

The leak was visually confirmed by EnCana officials at 9:52 a.m., and about 15 minutes later EnCana notified residents to evacuate, according to the report.

“The commission notes that it would be impractical for EnCana to notify residents or prepare for evacuation upon receipt of every alarm,” regulators stated in their review. “However, in this instance, there were indications of an active gas release available to EnCana prior to the 9:52 AM visual inspection.”

In a report, the commission said an investigation determined that EnCana did not begin notifying area residents to evacuate until 71 miles after the first alarm and didn’t notify provincial officials until almost an hour after employees visually confirmed the leak. EnCana’s emergency response plan also was out of date at the time of the gas leak, the report stated.

“The commission determined that EnCana’s response to this incident did not entirely conform to their Emergency Response Plan,” said regulators. “The flow of information within EnCana was effective but delays in external notifications reduced the overall effectiveness of the response.”

The investigation concluded that the leak was caused by sand in the pipe, which eroded the side of the pipe and caused it to burst under pressure. According to the OGC, EnCana did not properly clean the well after it was built, which resulted in too much sand in the gas stream. Investigators also found that the emergency shutdown values were not located in the correct place on the pipe, so when the valve was closed it had no effect on the leak.

BC regulators made 12 binding recommendations, which will require EnCana to put all of the emergency shutdown values in the correct place and prepare a detailed report for the commission to indicate what has been done. EnCana also has to submit a report to authorities concerning what it undertakes to add more controls and monitoring at all wells within three kilometers of a residence.

The OGC also scheduled a meeting with Pouce Coupe residents for the coming week.

“While some time has passed since this incident, our focus has been on consulting with impacted residents, implementing changes resulting from our findings to-date and providing information to the BC Oil & Gas Commission for their independent investigation,” EnCana officials said.

The Calgary-based producer also said it has undertaken several actions to enhance public and worker safety:

“We remain focused on continued education and consultation with residents in this region and reinforcing the safety and integrity of our operations,” the company said.

The Pouce Coupe area is where an unidentified bomber last June caused a pipeline blast that damaged one of EnCana’s gas wellheads. EnCana crews were repairing the damage when a second blast occurred in the same area on July 4, officials said. At that time, EnCana was able to shut the pipeline with no injuries and minimal damage, officials said (see Daily GPI, July 7, 2009). The incidents were said to be similar to four previous bombings on EnCana pipelines that occurred in late 2008 and early January (see Daily GPI, July 31, 2009).

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