BY STEPHEN L. HERMANN
An accident involving an overturned tractor-semitrailer and trailer combination occurred on Interstate 10 about 40 miles west of Phoenix, Arizona. The driver apparently fell asleep around 6:30 a.m. and drifted off the right side of the road. He hit a raised approach to an overpass, and it flipped the entire rig. The units ended up on their right sides, completely blocking both eastbound lanes of the interstate highway.
An Arizona Department of Public Safety (DPS) commercial vehicle safety specialist (CVSS) was conducting truck inspections nearby and was on the scene within three minutes. The CVSS officer noted the FLAMMABLE placards on both trailers; the driver explained he had been transporting a mixed load of flammable liquid hazardous materials and general freight. The driver was slightly injured and was evacuated by ground ambulance to a medical clinic 10 miles away.
The CVSS officer called for assistance to reroute eastbound traffic and requested the DPS hazardous-materials team. As the department’s hazardous materials coordinator for the past 15 years, I responded to the scene.
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 (2) The driver received minor injuries in the accident, which heavily damaged both trailers. (The liquid on the ground is fire hose runoff from a leaking coupling.) |
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During my 30-minute drive, the CVSS officer advised me by radio of the proper shipping names and quantities of the hazardous materials in the trailers. It was a short list of basically PVC pipe cement small containers. At this point, I set the stage for one series of small mistakes after another that could have led to major problems. My thought processes as I headed with flashing lights and siren to the scene were as follows:
1. This was a “ho-hummer.” Even half paying attention, I couldn’t mess this one up. Innocuous material in small containers was involved. There were life safety exposures and no nearby structures. The accident was in the open, with an approximate 10-mile-per-hour wind blowing to dissipate any flammable liquid vapors.
2. It got me out of several boring hours of writing memos and checking paperwork, which would, as always, be punctuated by several phone calls to prolong the tedium.
3. It was a pleasant spring day, with temperatures forecast in the high 70s and no unusual weather expected.
4. Our departmental procedures give the hot zone to the hazardous-materials team, so other Highway Patrol officers would handle the interstate traffic problems and I could focus solely on the haz-mat problems.
5. Having handled more than 150 hazardous-materials spills around the state, I knew, and enjoyed working with, all of the cleanup contractors out of Phoenix. We all knew each other and functioned smoothly together. In short, life was good.
Therefore, no small amount of complacency was settling in even before I arrived at the scene. The CVSS officer gave me a good listing of the hazardous materials involved and also advised he had requested dispatch of the department’s mobile command post (CP) vehicle. This unit has complete communication capabilities, a small meeting room, and other normal CP facilities.
ON-SCENE ASSESSMENT
When I pulled up to the scene, the CVSS officer handed me several pages of shipping papers describing the chemical load. I glanced at them to confirm his report and went to the fire truck at the scene. Although Arizona has no county fire departments, a volunteer fire district about 13 miles away had responded to the scene, and I was glad to see several fire officers and firefighters I had worked with before in this area. They said they had checked the overturned trailers and had seen no evidence of a haz-mat spill. They had pulled several hoselines and agreed to stand by for the duration of the incident.
I had several haz-mat detection instruments ready to use and walked around the trailers. There was no apparent liquid spill, so I placed the instruments about one foot inside the damaged rear door of one trailer to check for readings. The combustible gas multifunction instrument indicated zero percent of the lower explosive limit, normal oxygen, and no carbon monoxide or hydrogen sulfide detected. The far more sensitive photoionization instrument indicated between 15 and 20 parts per million (ppm) of a detectible vapor.
One of the inherent limitations of the photoionization instrument is that it won’t tell you what it has detected, just that a certain level of something is present. In this instance, it was logical to assume that one of the flammable hazardous materials in the load had leaked and was off-gassing vapors, which were being detected.
At the first trailer’s damaged rear door where I was taking readings, the wind was at my back and blowing into the damaged trailer. I went around to the front trailer corner, where about a six-inch hole had been created in the wall, and detected about 40 ppm from the wind blowing through the trailer and moving vapors. A check of the other trailer indicated about 10 to 15 ppm.
I then telephoned the corporate headquarters operations department for the trucking company to discuss arrangements for handling the accident. The company operations officer said that he would dispatch the terminal manager from Phoenix with a crew to handle the situation. I explained that my tentative instrument readings indicated a potentially significant flammable liquid spill. I had checked the shipping papers from the load; one of the components of several of the flammable liquids had a permissible exposure level (PEL) of 100 ppm established by the Occupational Safety and Health Administration.
Since it was safe to assume that readings directly above the spill inside the trailers would be higher than this, it meant the cleanup personnel would have to wear respiratory protection. I asked if the Phoenix terminal people had been trained in and equipped with self-contained breathing apparatus or even cartridge respirator masks, and the answer was no. This meant they could not go inside the damaged trailers and qualified cleanup contractor personnel would have to do the work immediately around the spill.
The operations officer contacted a cleanup contractor, which was soon en route. Within an hour the Phoenix terminal manager arrived, and we discussed the operation. He wanted to use his personnel to handle the freight after it was removed from the damaged, overturned trailers to reload it into other trailers to continue on. We agreed that as long as there were no instrument readings approaching the PEL that his unprotected personnel could do this work but that cleanup contractor personnel with respiratory protection would have to do the “inside” work in the damaged trailers.
 (3) Both trailers were removed to the median for unloading so the roadway could be reopened. |
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 (4) Tests conducted with a sensitive photoionization instrument determined that flammable liquids were leaking from damaged packages inside both trailers. |
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LEAKING CONTAINERS DISCOVERED
When the cleanup contractor personnel arrived, a safety briefing was conducted and work got underway. Several dozen leaking one-gallon flammable liquid packages were found, and they were placed inside an open-head 55-gallon overpack drum with absorbent material. This is a common method of handling leaking containers in the field and is specifically provided for in the Department of Transportation hazardous materials transportation regulations.
The work proceeded smoothly with the first trailer; within two hours, cleanup contractor personnel were unloading the items from the second trailer. About halfway through the load, cleanup personnel found a package with both SPONTANEOUSLY COMBUSTIBLE and CLASS 9 DOT package labels and marked “SELF-HEATING SOLID, ORGANIC, NOS, HAZARD CLASS 4.2, UN 3000.” Work immediately stopped, since my check of the shipping papers did not show any spontaneously combustible hazardous material in the load. At this point the terminal manager mentioned he had brought shipping paper copies, and we checked them.
Sure enough, there was a complete shipping paper for the spontaneously combustible package. We had been working for hours unloading the damaged trailers without realizing that there was a package filled with a material that, had it leaked, could have started a fire. Why didn’t I know it was there? I had gotten complacent and missed three opportunities to discover its presence:
1. On my arrival I simply accepted the shipping papers from our CVSS officer and failed to check inside the cab to look for more.
2. When I talked to the operations officer on the phone, I had failed to ask him to check his computers to confirm my listing of chemicals present.
3. When the terminal manager had arrived, I failed to ask him if he had copies of shipping papers, which I should have checked.
In short, I had gotten sloppy and complacent and failed to follow normal procedures to ensure we had complete knowledge of the hazards with which we were working. I had presided at hundreds of spills, and this one appeared to be so routine that I jeopardized everyone present by failing to follow normal assessment procedures.
We determined that the spontaneously combustible material package was undamaged and not leaking. The operation was safely concluded within an hour.
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LESSONS LEARNED
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There were one primary, major “lesson learned” and several reinforcing teaching points from this incident, which could have had a far different ending:
1. Always conduct a complete hazard assessment using all resources at your disposal, and double check it at every opportunity.
2. Major trucking companies have the ability to check their computers for a complete listing of all hazardous materials present.
3. A carrier can print out and bring to the scene copies of shipping papers for the trailers.
STEPHEN L. HERMANN retired as the hazardous materials coordinator for the Arizona Department of Public Safety and as Arizona’s senior state-on-scene-coordinator for hazardous materials emergency response. He is also a retired U.S. Army Reserve Chemical Corps colonel. He has supervised more than 200 serious hazardous materials highway and rail incidents over the past 25 years. He has a bachelor of science degree in explosives technology from the University of Minnesota and is a graduate of the U.S. Naval School Explosive Ordnance Disposal, United States Army Command and General Staff College, and the U.S. Army War College.
