ROLLOVER TANKER PUTS TRAINING TO THE TEST
Photos by Jerry Cleveland.
On August 16, 1990, the Denver (CO) Fire Department received a call for a rollover tanker on Interstate 70, metro Denver’s main east-west artery. What ensued was an incident that caused the worst traffic jam in Denver’s history and tested the training and expertise of department personnel. In all, more than 100 firefighters and specialists, including representatives from several outside agencies, cooperated for nine hours to mitigate the situation. Denver fire officers credit training, mutual aid, and deliberate, step-by-step planning for the safe and successful resolution of this potentially explosive incident.
INITIAL RESPONSE
Truck 9, Engine 9, the haz-mat response team, and the District Five chief were dispatched immediately. Arriving first with Truck 9, Lieutenant Jack Schnur found an MC306 aluminum tanker truck on its side with liquid product escaping from its damaged access ports at what would normally be the top of the trailer. As per standard operating procedure, Schnur initiated the Denver incident command system and assumed command of the incident. The truck’s shipping papers indicated that the product in the tanker was 7,300 gallons of unleaded gasoline. This was confirmed by the truck driver, who was uninjured. Schnur briefed both dispatch and the arriving haz-mat team. He established a hot zone and ordered all personnel within it to wear full turnout gear, including gloves and Nomex hoods, proximity suits, and SCBAs.
Schnur then directed crews to build a diversion dike to catch the leaking product, using dirt from the department’s tandem-axle, five-yardcapacity dump truck that, when necessary, accompanies first-in units to calls for potentially large spills. He then assigned incoming engines to hook up to hydrants at the perimeter of the highway area and stretch handlines to the scene.
Fortunately, the tanker had flipped onto a highway depression that formed a natural holding pond for the escaping product. Nevertheless, as a precaution crews sealed storm sewers with visqueen and dirt to reduce the likelihood of the product contaminating the storm drainage system. Firefighters confirmed that the overturned tanker was stabilized, placed dome-clamp hatch covers over the access ports to minimize leakage, and applied a thin layer of AFFF with a dirt cover over the exposed product on the ground.
Responding from DFD headquarters in downtown Denver, District Five Assistant Chief George Garrod copied the radio briefing from Schnur. He called for a turret-mounted crash rig from Stapleton International Airport. In turn, Assistant Chief Dennis Hixon of airport command requested and received FAA permission to dispatch the vehicle off airport grounds. Hixon also supplied DFD with a foam trailer attached to the crash truck.
Upon arrival, Garrod received an incident status briefing from Schnur. Garrod directed crews to move back farther away from the tanker and set up his command post on an elevated section of 1-70 approximately 200 yards from the overturned vehicle. Then he made certain that all ignition sources brought to the scene had been eliminated and requested that the utility company cut electrical power to the area, since the tanker had knocked down a power light pole. All additional incoming units and personnel were sectored, and an operations chief and safety officer were designated.
After conferring with his officers, Garrod decided to restrict bystanders and highway traffic. Both 1-70 and the heavily traveled Colorado Boulevard adjacent to it were ordered closed because of the obvious explosion potential. Garrod and his officers realized that the department would take some heat from the public and press for closing down major roadways, thereby causing huge traffic tie-ups, but safety was the first priority.
OFF-LOADING THE PRODUCT
Command now was faced with the challenge of off-loading the gasoline in the safest and most effective way. Uprighting the tanker prior to product removal was never an option; not only had the vehicle’s structural integrity been compromised, but the single-wall design of aluminum tankers makes such an operation extremely dangerous. Given the tank’s baffle design, Garrod and his staff realized that their only viable alternative was the drill-and-pump method of product removal (also referred to as “hot tapping”), in which a pneumatically driven holesaw opens holes in tank compartments through which product is pumped into a stable container parked nearby. Ironically, only two weeks prior to the incident a number of DFD personnel had attended a training session on this same technique, conducted by the Amoco Oil Company.
Before performing the drill-andpump operation, several important steps were taken:
- DFD requested the assistance of Amoco technicians for their expertise and equipment, particularly a nonsparking pneumatic drill and holesaw.
- With the temperature approaching 90 degrees, and with no breeze, shade, or cloud cover, heat stress became a consideration. Thus Garrod requested mutual aid from the City of
- Aurora Fire Department’s haz-mat team. Aurora’s haz-mat technicians merged with Denver’s to form teams that would be rotated throughout the operation. An additional group comprised of personnel lacking specialized haz-mat training was to provide liaison support. The Salvation Army responded and played an important role in the hydration and cooling effort.
- Personnel rehearsed the planned procedure both on paper and with a walk-through session. This was well worth the time and effort. A procedural omission was brought to the attention of the incident commander, and the situation was rectified. The practice run helped all personnel focus on their exact goals during the real operation.
- Explosimeters were placed in service to measure flammable vapor accumulation around the truck and nearby areas.
- An empty tanker was brought to the scene and positioned for product transfer. Personnel grounded the overturned tanker to a copper rod set as far away from the truck as possible, bonded the “bad” tanker to the transfer tanker, and then grounded the transfer tanker. This virtually eliminated the explosion potential from static electrical charges on either vehicle.
- Engine company crews were positioned to protect firefighters who would be performing the removal and transfer operation.
- The airport’s turret-mounted crash vehicle with foam trailer was positioned within 100 feet of the overturned tanker.
With all possible precautions taken, haz-mat teams began removal and transfer operations. Personnel mounted the tanker to drill the openings. Baffle design made it necessary to drill two holes for each of the five tanker compartments. Some manufacturers place baffle openings at the three and nine o’clock positions, thus allowing product to pass through the baffles if the tank falls on either of its sides (and making it necessary to drill only one hole per compartment); however, this was not the case with the overturned tanker in this incident.
Personnel liberally applied light water (AFFF) to the working area. Although this served as an effective lubricant/coolant and also served to exclude some air from the immediate area around the saw cut, it made the aluminum surface extremely slick and difficult to work on. It took the coordinated efforts of four two-member teams to drill each hole. Two firefighters were needed just to start the pneumatic drill into the tanker and keep it stable, and each hole took on average 15 to 20 minutes to make.
A siphon “stinger” tube was inserted in each hole and enough flammable product pumped out (via a PTOdriven pump from the good tanker) to drop the liquid level below the domes and eliminate the leak problem. Wooden plugs were placed into the holes to prevent any further product escape during completion of product removal and transfer.
The successful off-loading was a slow, methodical, and careful process. Amoco personnel were consulted every step of the way. After off-loading, the Environmental Protection Agency’s Region 8 staff and Amoco technicians suggested that all compartments be filled with dry ice to render any residual vapors inert. This was done. However, the physical reaction between the gasoline vapors and the gaseous carbon dioxide (CO2 sublimes directly from the solid to the gaseous state upon melting) pressurized the tanker and almost popped the wooden plugs used to stop the holes drilled in the tank.
LESSONS LEARNED AND REINFORCED
- As for most large-scale incidents, mutual aid was a key to effectiveness. This response illustrated the need to train with other fire departments and private sector agencies within the response area. Through their interagency training at the Rocky Mountain Fire Academy, DFD officers had a complete list of the available equipment for special emergencies like this one and how long it would take to get it to the scene. With a dynamic mutual-aid program, haz-mat trucks do not necessarily have to be optimally equipped; mutual aid offers a costeffective alternative to specialized, seldom-used, and very expensive equipment.
- It’s important to know your resources and consider the perspectives of different groups. DFD received effective, expert advice from the Aurora Fire Department’s haz-mat team, Amoco Oil personnel, EPA personnel, and the utility company.
- It’s important to recognize when to act swiftly and when to deliberate. First-arriving Denver companies acted with speed and confidence to meet initial incident priorities. Once initial strategy was achieved, the nature of the incident afforded the commander time to approach a delicate operation with maximum thoroughness.
- Priorities must be established— the first for any incident being life safety. In this particular incident, envi-
- The drill-and-pump procedure was difficult. This was exacerbated by the slickness of the AFFF applied to the tank for its lubricating and cooling effect. Members found the footing precarious. A slow, careful performance of this tactic is warranted.
- It’s important to consider the physical needs of responders, particularly at long, physically taxing incidents, to prevent heat stress and dehydration. Crews must be rotated, cooled, and hydrated. In the postincident critique, members mentioned that an air-conditioned bus that had been requested from the regional transportation district would have helped in the cooling effort, but the bus had not been provided.
ronmental considerations were the second priority, and from the firstarriving units to mitigation, department operations reflected that concern. This is a concern that is considered a high priority for all haz-mat incidents.
Nonsparking equipment must be used.
