Volunteer firefighters from Seeley Lake, Condon and Potomac responded to Locust Lane and Tamarack Drive in Seeley Lake Saturday morning for a propane leak. The liquid withdrawal valve on a 500-gallon propane tank was bumped and cracked by a skid steer that was being used to remove the snow around the tank.
The damaged valve (left) next to a new valve. It was estimated that more than 400 gallons of liquid propane escaped through an opening around a tenth of an inch. One gallon of liquid propane expands to 270 gallons when vaporized. The propane cloud generated by the escaping propane could be smelled on Highway 83. However Seeley Lake Fire Chief Bob Vanden Heuvel said the only dangerous levels were within a 30 foot radius of the tank once they had water on it. Energy Partners Branch Manager Michael Henry broke the valve completely and plugged the hole with a wooden peg before he was able to move the tank.
The damaged valve was the liquid withdrawal valve located on the top of the tank (pictured here on a new tank). It has a hose that goes to the bottom of the tank allowing the tank to be emptied. Emergency responders were forced to wait until the tank was empty before they could remove it.
SEELEY LAKE – Emergency personnel from Seeley Lake, Potomac, Condon and Missoula responded to a propane leak from a broken valve on a propane tank Saturday, Feb. 4 just after 10 a.m. Volunteer firefighters secured the scene on the corner of Locust Lane and Tamarack Drive in Seeley Lake while Seeley-Swan Search and Rescue (SSSAR) and law enforcement officers evacuated the immediate area. No one was injured and Energy Partners removed the propane tank after all of the product was emptied.
Seeley Lake Fire Chief and Incident Commander Bob Vanden Heuvel said snow had come off the roof and buried the propane tank. The owner of the property was using a skid steer to clear the snow around the tank.
While the cause is still under investigation, Vanden Heuvel said from their initial assessment, the front end of the skid steer bumped a valve.
Energy Partner’s Seeley Lake Branch Manger Michael Henry said the valve was the liquid withdrawal valve. The valve has a pipe that goes all the way to the bottom of the tank that allows the tank to be emptied.
Henry said that while snow coming off a roof can damage piping that attaches to the tank, the problem in this case was the method used to remove the snow from around the tank. Snow should be removed from a tank by hand with a shovel, never with equipment. Because the tank had just been filled when it was bumped, the tank did not move but the valve cracked.
Vanden Heuvel said while the valve was not hit hard, it was enough to strip the threads and crack the valve. The propane then started spraying out of the hole that was around a tenth of an inch.
Vanden Heuvel said when the skid steer operator realized he had hit the tank, he backed up and parked the equipment. He then called 9-1-1.
Because the valve was not sheared off entirely, the hole could not be plugged. Responders were forced to wait until all the propane vented out of the tank. Vanden Heuvel said the 500-gallon tank was close to its maximum fill.
Vanden Heuvel ordered the Missoula County Hazmat Team because the fire department does not specialize in hazmat. They respond as first responders and have three main goals, identify the product, isolate the incident and protect the public.
The leaking propane vaporized created a propane cloud. Vanden Heuvel said that propane needs the proper mix of gas and oxygen as well as an ignition source to ignite.
“It was just a matter of not letting the propane get to that perfect mix where it is explosive and find an ignition point,” said Vanden Heuvel.
Volunteer firefighters from Seeley Lake, Potomac and Condon surrounded the cloud and the tank from a relatively safe distance and sprayed it with two to four fire hoses at a time in an attempt to disperse the cloud and keep it contained.
“If the cloud were to detonate at that point, the flash is controlled [with the water],” said Vanden Heuvel.
The evacuation effort by law enforcement and SSSAR was well underway by 10:30 a.m. They evacuated homes four-five blocks east of the incident and on Tamarack Drive. They also blocked the roads accessing the area. Highway 83 was never officially closed.
“[When the cloud is dispersing] it is basically the oil mercaptan that you smell. Once the water was on the cloud, there were really no explosive levels past 30 feet in all directions,” said Vanden Heuvel. “We still didn’t want to take any chances.”
After the tank was determined to be empty, crews went house to house in the area testing the propane levels in homes with propane gas monitors to ensure there were no dangerous levels of propane.
“It was really good teamwork with a unified command with the Sherriff’s Office in with us,” said Vanden Heuvel. “A lot of volunteers showed up and pitched in. It was the community coming together to keep the community safe. The Missoula Hazmat Team [who arrived after the incident was resolved] were impressed that we were able to handle the situation without having anyone injured or having it ignite. I’m very proud of our fire department and the way the system worked.”
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