Chemical Safety Board Probes ConAgra Explosion

A faulty gas line connection at a recently installed large, industrial hot-water heater is suspected of leading to the deadly explosion and fire at the ConAgra Foods plant in Garner, N.C., on June 9. The accident killed three workers and injured some 40 people including three firefighters who suffered from ammonia inhalation. At least four workers are in critical condition because of burns, according to local accounts.

The Chemical Safety & Hazard Investigation Board (CSB) is investigating the accident at the 400,000-plus-sq-ft plant that produces Slim Jim beef jerky. As yet CSB investigators are unable to access the specific area where the accident occurred as it remains covered in rubble and is considered unsafe.

Speaking at a June 18 news conference in Raleigh, N.C., CSB Investigations Supervisor Donald Holmstrom said eight CSB investigators were at the site and had conducted 120 witness interviews. The board has also brought in two blast reconstruction experts to help determine what happened during the noon-time explosion and fire.

Although investigators have yet to be able to enter the specific accident area, Holmstrom said they have an "emerging understanding" of what happened, primarily based on interviews.

The accident occurred when ConAgra contractors were in the process of installing a new industrial-scale, gas-fired water heater, he said. The 8-foot-tall, 4.5-foot-diameter heater ran on natural gas or propane and was located in a pump room in the interior of the plant in a packaging area.

A new gas line several inches in diameter had been installed between a gas main on the roof and the pump room only a week before the accident. On the morning of the accident, one of the contract firms was putting the new gas line and heater into service and purged the line. CSB is examining the possibility that gases inside the line were purged and vented directly into the pump room, Holmstrom said, and led to the explosion.

An ignition source has not been determined, but CSB Chairman John Bresland, also speaking at the Raleigh briefing, noted that ample ignition sources are available in an industrial plant.

"The current focus of our investigation is to determine why flammable gas was released into the midst of an occupied building with about 100 people in the immediate vicinity," Holmstrom said. "We will also be examining the appropriateness of locating the heater in the center of the building within a structure that was susceptible to explosion damage."

The board also is examining the role of ammonia, which was reportedly released in the accident, Holmstrom said. It was unclear when a preliminary report will be issued; the board usually takes nine months to a year to complete an investigation.