A Great way to Learn

Kem Russell

The following incident had many lessons learned for both the facility and the outside responders. Think about what would happen, or what actions would be taken if this happened at your facility.

Roy was backing up his forklift near the cherry processing line. And for whatever reason Roy didn’t stop till the forklift slammed into piping for hydro-cooler # 4.

The impact completely separated the flange on the downstream side of the back-pressure regulator, allowing pressurized vapor to escape from both the associated surge drum as well as from the main suction line. This being cherry season there were over 100 people in the large processing room. Those closest to the release point were quickly confronted with a very high concentration of ammonia vapor, and they immediately began to self-evacuate. Unfortunately, as anyone who has been around processing lines knows, many times there are no easy or fast ways to escape some areas. Almost all of the people escaping the area suffered injuries, not only from the ammonia concentration but as they hit stainless steel equipment and supports in their mad escape.

People on the east side of the packing line filling stations were forced to escape through the invisible vapor cloud due to equipment arrangement. All of these people had injuries to their eyes and respiratory tract.

Lesson to Learn: How can people escape from all areas during an ammonia release?
People along the sorting tables encountered strong-smelling ammonia vapors as they escaped, which caused them not to stay on their primary evacuation route.

The few Supervisors in the large room initially didn’t know what was happening, until one of them got a smell of ammonia. The situation on the packing line had gone from orderly, to chaos in less than a minute. A few minutes later one of the Supervisors who had gotten outside notified the refrigeration operator about the release near hydro-cooler #4. The refrigeration operator immediately used the control system to shut down the hydro-cooler zone. This action de-energized the liquid feed solenoid to the hydro-cooler surge drum, and also de-energized the back-pressure regulator pilot solenoid. At this time the refrigeration operator didn’t know that due to the break location ammonia vapor was still releasing from the main system suction line.

Evacuation from the room was quick and soon people were outside and gathering at the assembly points. While a headcount was going on, one Supervisor called 911 explaining that they had an ammonia release and needed help. The 911 dispatcher already knew something was happening from the numerous previous calls from many escaping employees.

Lesson to learn: If people have cell phones they will call, which may be helpful, but can create confusion depending on the messages 911 receives.

Due to the situation, this quickly became a two-alarm event, calling in additional resources. After about 12 minutes from the 911 notification, fire trucks, and aid units began arriving at the scene. Fortunately, the Captain on the first in-engine had dealt with a few other ammonia incidents. Unfortunately, there was no hazmat response trained men among the responding groups, and outside assistance from State or Federal groups would be hours away.

Knowing the normal wind direction helped the first in-engine quickly establish a safe location to set up command. Also, having wind indicating flags on top of some of the light poles helped. However, the Fire Captain did mention that it was good that this incident happened during daylight since he had previously been at the facility in the dark and he couldn’t see the flags on top of the light poles. Just the bright light.

Lesson to learn: Positioning of wind indicators matters.
The arriving responders were quickly overcome with patients, and this became an MCI “Mass Casualty Incident”. The trained responders began separating people into Green, Yellow, and Red groups based on a quick assessment of a person’s injuries. A “Black” tag would have been used for a fatality and at this point there were none. However, until the headcount could be completed, it was unknown if everyone had gotten out.

The refrigeration operator soon arrived at the command post and he and the Fire Captain started discussing what was happening and what could be done. The Fire Captain asked, “Is the ammonia leak stopped, and if not, how could it be stopped?” The operator replied that he had shut down the zone.

When the refrigeration operator said he had shut down the zone, the Captain immediately asked, “What’s a zone?” The operator explained that using the control system he had turned off the liquid make-up and the suction control valve “BPR” to the equipment or zone that he had been told was the source of the release. The operator explained, “So if the liquid line and solenoid are not damaged that should stop any liquid. And with the BPR pilot off no vapor should be released until the pressure in the surge drum gets to about 85 psig.”

“Anything else that could be done?” asked the Captain. “I forgot, I also closed the King valve in the machine room,” replied the refrigeration operator. “It won’t take long before that zone and all the rest of the system runs out of liquid.”

“I could also close the hand valves in the liquid and suction lines that lead to all of the hydro-coolers in the room, but I’m going to need help to do that. Those valves are located up high in the piping on the outside of the east side of the building. I need a scissor lift to get to the valves, and unfortunately, ours is in the shop. I can also lower the system suction pressure to pull down the zones.”

“What do you mean by pull down?” asked the Captain. Lesson to learn: Jargon difference, which training with the outside responders will help overcome. “I’ll lower the operating pressure of the compressors, which will remove more vapor from the system, which could help, depending on where the break is. If the suction line is open someplace, it won’t take too long for enough air to be sucked into the system to raise the discharge pressure, and I will have to shut down the compressors,” replied the refrigeration operator. “Do what you can with the system, and we’ll get a ladder truck so you can access those shutoff valves”, said the Captain.

Another refrigeration operator went to the machine room to start the pump down, while a plan was developed to get to the shutoff valves. In the meantime, the headcount results were reported to the Captain. Everyone was accounted for, except Roy.

With plans in place to reduce and/or stop the ammonia release, they started developing a plan to ventilate the entire building. To do this “Positive Pressure Ventilation” (PPV) would be done using the high CFM gasoline-powered fans from several fire trucks. The challenge was determining what doors were open or closed within the facility. The memory of a couple of supervisors about possible door positions was the best information. The hope was to push the ammonia out an outside roll-up door, and not into other rooms within the facility.

By this time about 40 minutes had passed, and a hazmat response team from another company in the area had arrived on the scene. Their assignment was to search for the one missing person, Roy.

The incident described above didn’t actually happen, but it could have. This was an ammonia release scenario used in a Dual County Table Top Exercise, in which the company that had the Cherry line was involved. Those attending the exercise were: Fire Departments who would be responding; 911 Dispatch; Law Enforcement; County Office of Emergency Management; State Department of Ecology Spill Response; Hazmat team representatives from the only company in the area that had hazmat response capability; and an ammonia specialist. A representative of the Office of Emergency Management worked as an overseer to keep all groups on task through the various stages of the table top exercise.

The entire exercise lasted 1.5 hours and was video recorded for people and groups who couldn’t attend. This table top exercise resulted in all that were involved learning things they could do better should an actual ammonia incident occur, as well as many things they hadn’t thought of before. Table Top Exercises can be a valuable method in helping companies and responders be better prepared for any kind of ammonia incident. Large or small. Use them.