On Saturday afternoon, October 6, 2007, a tremendous explosion and fire erupts at the Atlas Castings and Technology foundry in Tacoma, injuring the driver of a propane tanker truck and three foundry workers. The truck driver, Charles W. McDonald (1943-2007), age 64, is severely burned and will die a week later at Harborview Medical Center in Seattle. The subsequent investigation will determine that the accident was caused by a faulty connection between the 8,000-gallon tanker truck and two stationary propane tanks. Liquefied propane gas, released during delivery, was ignited by a hot electric-arc furnace inside the foundry. Damage to Atlas property is estimated to be $14 million.
Atlas Castings and Technology
Atlas Castings and Technology (formerly Atlas Foundry & Machine Company) is located at 3021 S Wilkeson Street, between S Tacoma Way and S Center Street, in the industrial section of Tacoma, south of the Tacoma Dome. The factory occupies 18 acres and has more than 500,000 square feet of covered manufacturing space. Established in 1899, the foundry began by fabricating iron castings for the logging Industry. In the 1930s, Atlas began making steel as well as iron castings, which soon became half of the foundry’s production.
Over the ensuing decades, Atlas established an excellent reputation for engineering and manufacturing high-quality steel castings used in a variety of critical industries including shipbuilding, nuclear power, chemical manufacturing, oil refining, and offshore drilling among others. Atlas also made the large, multi-ton splay saddles that hold the main suspension cables on both the second (1950) and the third (2007) Tacoma Narrows bridges. According to the Tacoma-Pierce County Economic Development Board, Atlas Castings and Technology was the county’s 44th-largest employer in 2007, with more than 500 employees.
At approximately 3:00 p.m. on Saturday, October 6, 2007, a powerful explosion shook Tacoma’s industrial area near the interchange of Interstate 5 (I-5) and state Route 16 (SR-16). Witnesses several miles away felt the concussion and saw a huge fireball shoot hundreds of feet into the air. The blast shattered windows in nearby businesses, cut electrical power to some 13,000 customers, and prompted a mass evacuation of the surrounding neighborhood. Smoke and falling debris forced the Washington State Patrol (WSP) to shut down portions of the state highways through Tacoma, backing up traffic for miles. The Federal Aviation Administration (FAA) issued temporary flight restrictions, prohibiting aircraft from flying within five miles of the area.
The event occurred at the Atlas Castings and Technology foundry where an 8,000-gallon tanker truck, delivering liquefied propane (LP), exploded. Truck parts were strewn over hundreds of yards, destroying a nearby Tacoma Power substation and bringing down the electrical transmission lines. A large, flaming, two-axle portion of the chassis, pieces of the cab, and other debris, landed on SR-16, narrowly missing vehicles. Little remained of the tanker truck at the blast site except for the radiator, frame and wheels. The two stationary, LP storage tanks, 28,000 and 31,000 gallons in size, were spewing flames and in danger of exploding. The ground surrounding the stationary tanks was also on fire, fueled by a ruptured natural gas line.
The large explosion was preceded by two or more smaller blasts which prompted several calls to emergency 911 operators. Firefighters, sent into the area to investigate, were nearby when the tanker truck blew up. The Tacoma Fire Department immediately dispatched 20 fire trucks and 50 firefighters to the scene. When foundry workers, who had evacuated the plant, told firefighters there was the potential for an even greater explosion, the Tacoma Police Department closed off the surrounding area and ordered an evacuation of the neighborhood.
Firefighters tried to assess the situation from a defensive position, but had difficulty seeing the blast site because of the property layout. After rotating an elevated closed-circuit television camera on the SR-16 overpass, they were able to see flames emanating from the storage tank’s pressure release valves and fire underneath the tanks. Puget Sound Energy determined a natural gas line into the plant had likely been ruptured by the blast, causing the ground fire, and worked to shut off the supply.
Meanwhile firefighters positioned three remote-controlled monitors (water cannons) on a nearby storage lot at the corner of S Hosmer Street and S Tacoma Way, within 150 feet of the fire. One of the stationary tanks was said to contain approximately 11,000 gallons of liquid propane, and the other approximately 9,000 gallons. Firefighters continued to stream water over the tanks all afternoon and evening, hoping to keep them cool enough to prevent an even bigger explosion. They were careful, however, not to extinguish the flames emanating from the pressure relief valves because they wanted the propane inside the tanks to safely burn away. By the time the situation was fully under control, firefighters had used more than 4 million gallons of water.
A Life Lost
Fortunately, the explosions happened on a Saturday. The part of the foundry where the explosion occurred was not operating and there were only 32 employees working inside the huge plant. The Atlas evacuation plan mandated they assemble nearby for a head count. Although some workers were not able to reach the muster area, all were accounted for. Surprisingly, only three workers had been injured; one suffered flash burns and two had minor leg injuries. The men were transported by ambulance to St. Joseph Medical Center, 1717 S “J” Street, where they were treated and released. The driver of the propane tanker, however, was missing and presumed dead, but such was not the case.
The missing truck driver was identified as Charles "Chuck" Winston McDonald Sr., age 64, a contract employee for IXL Transportation Services of Molalla, Oregon. Although severely injured, McDonald managed to crawl through mud and debris to a workshop, some 40 yards from the scene of the explosion. He was inadvertently discovered by firefighters almost two hours later and rescued. Paramedics treated McDonald but determined he needed to be taken immediately to the Harborview Medical Center burn unit in Seattle. The FAA had closed the airspace above the area, so he was taken by ambulance to a landing pad in Fife and then flown in an Airlift Northwest helicopter to Harborview. McDonald, suffering burns over 75 percent of his body, was put in a medically induced coma and kept breathing with a respirator. Tragically, he died from medical complications on Sunday morning, October 14, without regaining consciousness.
Firefighters watched the smoldering remains of the fire throughout Saturday night, allowing most of the propane inside the two storage tanks to burn away. Meanwhile, Washington state Department of Transportation engineers examined the deck and piers of the SR-16 overpass and declared them safe. The highway was closed for 11 hours before the Washington State Patrol finally reopened it to traffic at 2:00 a.m. on Sunday morning.
Later in the day, Puget Sound Energy capped off the ruptured natural gas line and Tacoma Power workers restored electricity to the surrounding neighborhood. Investigators from the Tacoma Fire Department and Washington state Department of Labor and Industries arrived to survey the damage and launch an inquiry into the potential cause of the accident.
Propane Gas and its Hazards
The handling and transportation of hazardous materials, such as propane, is regulated by U.S. Department of Transportation (DOT). In Washington, enforcement of the regulations is generally the responsibility of the State Patrol. DOT requires truck drivers handling hazardous materials to undergo safety training and certification every three years. McDonald’s certificate was valid and current.
Propane gas is 1.5 times heavier than air and, if released, will not readily dissipate up into the atmosphere. It is extremely flammable and burns at approximately 940 degrees Fahrenheit. Liquefied propane must be stored in a pressurized tank. Its delivery process is highly regulated and accidents are rare. Typically, two pressure hoses, each rated at 1,700 pounds-per-square-inch, are used; one for delivery of the liquid propane into the storage tank and one to allow vapor from the tank to flow back into the tanker truck. McDonald’s equipment supposedly had a manual as well as an automatic system for shutting down the flow of propane in an emergency.
Investigating and Cleaning Up
The investigators started at the perimeter and methodically worked their way into the scene, trying to piece together what happened. Of particular interest was the sequence of events leading up to the explosion, captured on video tape by a security camera at the Atlas facility. The camera showed McDonald arriving in front of the two stationary tanks and begin the process of pumping liquid propane from his 8,000-gallon tanker truck. After connecting the pressure hoses, he was suddenly enveloped in a white cloud of propane gas escaping from truck. McDonald dashed to the cab and moments later there was an explosion which enveloped the rig. Investigators speculated he may have been attempting to turn off the propane delivery pump or possibly the truck's engine, hoping to eliminate a potential ignition source.
The cloud of propane gas sunk to the ground and spread inside a heat treatment building, approximately 75 feet away, where it was ignited seconds later by a hot electric-arc furnace. There were two minor explosions in this area, then the major one that demolished the LP tanker truck, knocked foundry buildings off their foundations, shattered windows, and sent a great ball of fire hundreds of feet into the air. Damage to Atlas Castings and Technology property was estimated to be $14 million and its smelting operation, heavily-damaged by the blast, would be out of commission for a month.
On Saturday, October 14, workers from D&G Enterprises arrived at Atlas Castings & Technology to prepare the two damaged propane storage tanks for disposal. Under the watchful eyes of the Tacoma Fire Department, the propane remaining in the two large tanks was bled away using a 90-foot hose. Flames from the volatile gas shot 20 feet into the air and burned for almost three hours. The empty tanks were subsequently removed from the site, taken to the D&G yard and cut up for scrap. Meanwhile, Atlas was in the process of obtaining permits for new propane storage tanks, but at a safer location on the property.
Cause of the Catastrophe
On Wednesday, October 24, 2007, the Tacoma Fire Department released the results of its investigation into the explosions the Atlas foundry. The report determined that the accident was caused by a mechanical failure in the propane supply line at the connection to the propane tanker that resulted in the release of a massive cloud of gas, which was ignited by a hot furnace inside the foundry. The report also noted that two Atlas employees worked on the rubber pressure-hose prior to the blast, but stopped short of assigning responsibility for the accident.
Duane Britschgi, Atlas Castings & Technology Chief Executive and President, explained that McDonald had asked two Atlas workers to help him join a heavy metal fitting to the end of the pressure-hose that connected the LP storage tanks to his truck. “Although the hose was provided by Atlas, it's the delivery driver's responsibility to make connection to the truck and to check the hose is safe to use. He's trained, if there are any issues with the hose or the connections, to red-tag it and not make a delivery. Was it the hose or the fitting or the connection? That's what all the forensics experts are working on,” Britschgi said (Tacoma News Tribune).
On Friday, April 4, 2008, the Washington State Department of Labor and Industries (L&I) released its findings as to the cause of the LP-gas explosion. According to the official report “the L&I investigation found that at the time of delivery, Atlas workers repaired the foundry’s damaged LP-gas fill hose, attaching the fill nozzle using fasteners that were not designed to withstand the pressurized LP gas. The delivery driver took the improperly repaired fill hose and began to unload the LP gas. Within seconds, the hose detached from its connection to the truck’s tank, allowing LP gas to rapidly flow from the open valve and fill the air with the explosive gas. In less than a minute, the LP gas ignited and the first explosion engulfed the truck and fill area. Eight minutes later, the heated tanker truck exploded, causing a second and larger explosion.”
L&I fined Atlas $19,200 for three serious health and safety violations: “not properly training employees on the repair and maintenance of pressurized LP-gas systems; using hose connection that were not rated for LP-gas service and would not withstand the pressure; not testing the repaired hose after assembly to ensure it was free from leaks under normal use.” Although not involved in the incident, Atlas was also cited for “not having a shutoff valve in the piping to protect against uncontrolled discharge of LP gas.”