Federal investigators say the Kleen Energy plant explosion in Middletown occurred after sufficient gas to fill a sports arena vented into a constrained area near several potential ignition sources.
Five men died in the Feb. 7 explosion, and a sixth died later from injuries sustained in the explosion.
The accident occurred as workers cleaned debris from inside natural gas pipes at the plant through a “gas blow” procedure, according to Don Holmstrom, a supervisor with the U.S. Chemical Safety Board (CSB), who provided an update on the investigation Thursday.
The procedure is intended to force gas through pipes at 650 pounds per square inch of pressure, according to Holmstrom. The gas was vented into the air through pipe openings located less than 20 feet off the ground, but was somehow constrained in what Holmstrom termed a “congested area” near the main building, where it concentrated into levels sufficient when sparked to produce an explosion.
During his presentation, Holmstrom displayed a photograph taken of gas issuing from a pipe the morning of the explosion.
“Initial calculations by CSB investigators reveal that approximately 400,000 standard cubic feet of gas were released to the atmosphere near the building in the final 10 minutes before the blast,” Holmstrom said. “That is enough natural gas to fill the entire volume of a pro-basketball arena with an explosive natural gas-air mixture, from the floor to the ceiling.”
