Report: Abandoned PSE gas line caused Greenwood blast; $3.2 million fine proposed

Seattle firefighters work to put out flames at the scene of a building explosion in Seattle's Greenwood neighborhood early Wednesday, March 9, 2016. (Genna Martin/seattlepi.com via AP) MAGS OUT; NO SALES; SEATTLE TIMES OUT; TV OUT; MANDATORY CREDIT

OLYMPIA, Wash. - A powerful gas explosion that leveled buildings in the Greenwood neighborhood of Seattle last March was caused by an improperly abandoned gas line that should have been sealed off but wasn't, the state Utilities and Transportation Commission staff said in a report released Tuesday.

The commission staff found that Puget Sound Energy, which owns the gas line, committed 17 violations of pipeline safety regulations and recommended a penalty of up to $3.2 million.

According to the UTC report, the immediate cause of the explosion was damage to the gas line by unauthorized persons. The damage allowed gas to escape, accumulate in the building occupied by Mr. Gyros restaurant, and ultimately explode.

But the ultimate blame rests with Puget Sound Energy, according to the commission staff, because the company abandoned the line in 2004 but failed to properly disconnect and seal the line, allowing it to remain in service for nearly 12 years without proper oversight.

The staff's findings and recommendation will next be presented to the three-member state Utilities and Transportation Commission.

The explosion and ensuing blaze caused extensive property damage and injured nine firefighters who responded to the scene. Several businesses are still shut down, while others are just getting back up and running.

UTC pipeline safety staff allege that PSE violated pipeline safety regulations by failing to:

- Abandon a service line according to federal standards

- Follow its internal pipeline deactivation plan

- Perform annual leak surveys of an active service line

- Perform atmospheric corrosion tests of an active service line at least once every three years, and

- Perform external corrosion tests of an active service line at least once every 10 years.

The gas service line that PSE believed was abandoned was located in a space not intended for human occupancy between the Mr. Gyros and Neptune Coffee businesses, the report said.

Witnesses said that the space around the gas line was frequently used by unauthorized individuals to store personal items. But due to the limited space, the individuals sometimes disturbed the gas line to access the area. Lab tests confirmed the line failed at the threaded connection due to applied external force.

Staff also recommended the commission require PSE to review all previously abandoned service lines to verify compliance and provide a plan for identifying and mitigating any additional unsuccessful retirements.

PSE challenged the staff's conclusions and the proposed $3.2 million fine, calling it "disappointing and excessive."

"The natural gas system at the Greenwood site was damaged by unauthorized individuals in a space not intended for human activity, with the resulting gas leak causing the explosion and fire," PSE said in a prepared statement.

"While we disagree with the UTC staff’s conclusions and recommended fine, we’re committed to the safety of our customers and the community and will continue to review the report as we prepare for final disposition of this investigation by the UTC commissioners," the PSE statement said.

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