CSB: Purged gas line may have caused blast

Investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives determined last weekend that a gas leak caused the June 9 explosion at the 425,000-square-foot ConAgra Foods plant on Jones Sausage Road.

The CSB and inspectors with the state Division of Occupational Safety and Health have interviewed 120 ConAgra workers in recent days to determine the cause of the gas leak and how that sparked the explosion.

Don Holmstrom, an investigation supervisor with the CSB, said the natural gas line leading to a new industrial water heater was purged on the morning of the explosion to remove air from the line. Outside contractors were working with ConAgra personnel to put the gas line and water heater into service, he said.

Investigators are looking at the possibility that the purged gases were vented into the pump room that has been identified as the site of the blast, Holmstrom said. They could have created "a flammable gas cloud" that exploded, he said.

The spark for the explosion hasn't been determined, Holmstrom said, and it might never be found because of the extensive damage in the 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," he said.

CSB Chairman John Bresland said he's never heard of someone venting gas fumes inside a building.

"In my mind, that would seem to be a risky operation," Bresland said.

Holmstrom and Bresland declined to name the contractor working on the water heater. Two ConAgra workers filed suit Monday against Southern Industrial Constructors Inc., a Raleigh mechanical contractor, blaming its crew for the blast.

"The people involved in the installation were also involved in the purging," Holmstrom said.

The lawsuit alleges that Southern Industrial improperly installed the gas-fueled water heater in the plant. David Stradley, the attorney for the workers, said Wednesday that permits issued by Garner officials for the work in the plant implicate the contractor in the blast.

Rod Pettey, an attorney for Southern Industrial, said in statements that the company's four employees who were at the ConAgra plant the day of the explosion weren't anywhere near the blast site and weren't responsible. The permits show the crew only tapped into an existing gas main on the plant's roof and didn't work in the pump room, he said.

Investigators plan to examine equipment at the blast site – explosion reconstruction experts are part of the CSB team – and review employee training records, ConAgra's selection of contractors and applicable fire codes and insurance standards as part of the probe.

"We want to be able to examine the incident scene to correlate ... witness statements with exact physical evidence," Holmstrom said.

Bresland said it's hard to determine when investigators will be able to get to the pump room because the site remains very unstable. The blast damaged about 100,000 square feet of the plant, he said.

"It was a very sobering site to see the impact of that explosion. It was a significant explosion and certainly a terrible tragedy for the people involved,” he said.

The CSB also plans to look into the release of ammonia from the plant into a nearby creek following the explosion. Ammonia is a flammable and toxic liquid, and the company uses it in its refrigeration operations.

Holmstrom said part of the ammonia leaked from pipes in the blast, and "a controlled release" was performed to drain the plant's lines and prevent further damage.

ConAgra spokesman Dave Jackson said the company plans to restart "limited production" of Slim Jim beef jerky products at the plant in August.  Some production also will be handled by a ConAgra plant in Troy, Ohio, he said.

The blast occurred in the packaging area of the plant, and Jackson said the company plans to hire an outside firm to handle packaging of Slim Jims produced in Garner.

Garner Mayor Ronnie Williams said ConAgra officials have assured him that the company will rebuild the plant and resume full production in the future. The plant employs about 900 people.

"The rebuilding is going to take place in a timely fashion, and the workers can go back to work," Williams said.

Four workers burned in the blast remain in critical condition in the North Carolina Jaycee Burn Center at UNC Hospitals in Chapel Hill. A fifth worker was in fair condition Thursday at the burn center, and a sixth was in good condition.

The hospital erroneously reported improvements in several patients' conditions on Wednesday.