MIDDLETOWN, Conn. – An explosion that sounded like a sonic boom blew out walls of an unfinished power plant and set off a fire during a test of natural gas lines Sunday, killing at least five workers and injuring a dozen or more.
The explosion at the Kleen Energy Systems plant in Middletown, about 20 miles south of Hartford, could be heard and felt for miles.
Deputy Fire Marshal Al Santostefano told the Associated Press on Sunday night that no one was known to be missing amid the rubble of the damaged plant. The cause of the gas explosion was unknown, he said.
The explosion left huge pieces of metal that once encased the plant peeling off its sides. A large swath of the structure was blackened and surrounded by debris, but the building, its roof and its two smokestacks were still standing. Rescue crews had set up several tents alongside the site, which is a few miles from Wesleyan University.
The explosion happened around 11:15 a.m., Santostefano said.
Santostefano said 50 to 60 people were in the area at the time of the explosion, and multiple contractors were working on the project, making it difficult to quickly account for everyone.
The 620-megawatt plant, which was almost complete, is being built to produce energy primarily using natural gas. Santostefano said workers for the construction company, O&G Industries, were purging the gas lines, a procedure he called a “blow-down,” when the explosion occurred.
Kleen Energy Systems LLC began construction on the plant in February 2008. It was scheduled to be completed by mid-2010.
Safety board investigators have done extensive work on the issue of gas line purging since an explosion last year at a Slim Jim factory in North Carolina killed four people. They’ve identified other explosions caused by workers who were unsafely venting gas lines inside buildings.
The board voted last week to recommend that national and international code writers strengthen their guidelines to require outdoor venting of gas lines or an approved safety plan to do it indoors.