What ignited Tacoma blast? It's still a mystery

A leak during the transfer of liquid propane from a delivery truck to a stationary tank may have been behind Saturday's dramatic fire at a Tacoma foundry.

But what ignited the flammable liquid gas, causing the tanker truck to explode, remains a mystery.

"There was some sort of malfunction that caused an explosion," Tacoma Fire assistant chief Dan Crotty said. "There was a leak, and the propane found an ignition source."

The transfer of propane from one source to another is a highly regulated, heavily controlled process because of its inherent dangers. Explosions are rare.

Charles McDonald, 64, the driver of the delivery truck, had been trained in the process, according to Bob Cox, CEO of IXL Transportation Services, for whom McDonald drives. McDonald remained in critical condition this afternoon at Harborview Medical Center.

The CEOs of both Atlas Castings and Technology, where the explosion and fire occurred, and IXL Transportation Services say a smaller explosion preceded the big blast, although the lull between the first and the second is not known.

A driver typically stays close to the equipment while overseeing the propane transfer, said Cox, of Molalla, Ore.-based IXL.

"It's amazing there were not more injuries," he said.

Saturday afternoon's explosion — which one Tacoma Police officer described as looking like "the atom bomb" — sent flames as high as 1,000 feet into the sky, shut down nearby highways, cut power to thousands and kept firefighters working into the night, spraying water on Atlas' two stationary propane tanks to keep them cool and keep them from exploding.

With the fire out, firefighters stopped spraying the tanks this afternoon.

The Washington State Patrol reopened Highway 16 near the foundry early this morning. Transportation Department engineers had to wait until fire officials determined they could safely inspect bridge piers beneath a stretch of the road.

Atlas CEO Duane Britschgi said in an e-mail that two foundry employees of the 32 working at the plant Saturday suffered minor injuries; one had facial burns and the other aggravated a bum knee.

The delivery truck, loaded with about 8,000 gallons of propane, exploded at the foundry near the intersection of Interstate 5 and State Highway 16 around 3 p.m. Saturday.

Tacoma Fire Department Deputy Chief Jolene Davis said the blast blew out windows in nearby industrial buildings, and the axle from the propane truck that exploded was found on Highway 16, at least four blocks from the site.

The Federal Aviation Administration, which established a 5-mile no-fly zone around the foundry on Saturday, lifted that around 3 a.m. today after authorities determined the site no longer posed a safety threat to aircraft, FAA spokesman Mike Fergus said.

Crotty said the debris field is about 1,000 feet. Some businesses near the foundry remain closed under Saturday's evacuation order, and the foundry still does not have power.

Crotty also said some buildings at the foundry were so damaged by either the explosion or the fire — or both — that walls and support beams moved.

"We don't want to put anybody inside there right now," he said.

Witnesses miles away felt the explosions and saw the flames.

Steve Lawson, a salesman at the nearby Titus-Will car dealership, said he went outside after he heard the explosion to see flames shooting up in the air. He said it was like a bomb going off. He said his wife, Carla, called him afterward to say she had just driven by and could feel the heat through the floor boards of her car.

The foundry, at 3021 S. Wilkeson St., is located in the Nalley Valley, an industrial area, with homes on the surrounding hills, near the intersection of I-5 and Highway 16.

According to its Web site, Atlas Castings & Technology, formerly known as Atlas Foundry & Machine Co., produces cast parts, some as large as 48,000 pounds, in more than 100 different alloys of carbon steel, low-alloy steel, stainless steel and nickel base material.

The company was founded in 1899, making iron castings for the Northwest logging industry. According to its Web site, the company occupies 18 acres with more than 500,000 square feet of manufacturing space. The company has worked around the world. Last year it built a steel cylinder that helped anchor a floating rig off the coast of South Africa. The company also has clients in China.

Last May, the company was taken over by AmeriCast, based in Atchison, Kan., and continued to produce steel casting for the oil and gas, nuclear power and other power generation industries, as well as the U.S. Navy.

Atlas also built parts of the new Tacoma Narrows Bridge — saddles that secured the cables for the bridge.

In 2002, a fire ripped through the foundry, causing about $850,000 in damage. That fire started in an area where some welding was done. A welding remnant apparently smoldered and led to the fire, officials said.

Investigators with the state Department of Labor and Industries will be looking into Saturday's accident, according to department spokesman Steve Pierce.

Stuart Eskenazi: 206-464-2204 or seskenazi@seattletimes.com. The Associated Press and Seattle Times reporters Lauren Vane, Tricia Duryee, Ben Romano, Linda Shaw and Susan Gilmore contributed to this report.