Disaster Averted - 55 Cents
Haz Mat team goes low tech to repair leaky chlorine gas tank near Schweitzer Mountain
The chlorine leak reported at the Sandcreek Water Treatment Plant the afternoon of January 8 was the third Sandpoint Fire Chief Robert Tyler had responded to in his three-decade career.
“It was something we were prepared to deal with,” Tyler said. “We had trained for it.”
But the incident was anything but routine.
Within hours of responding, crews believed they’d sealed off the leak and the problem was fixed, but late the next morning a worker returned to the treatment plant and once again smelled chlorine.
In the hours that followed, Tyler and emergency workers ran through all of the “what if” scenarios they could think of – including what could happen if there were a catastrophic failure of the leaking 150-pound tank.
An explosion could create a plume of toxic chlorine gas approximately 6 miles long and 2 miles wide, according to projections the chief received from a technician in Post Falls.
Depending on the direction of the wind, the plume could have enveloped the towns of Sandpoint, Kootenai and Ponderay.
Among the options the chief considered was evacuating residents in those areas and stopping all traffic on Highway 200 to the east and west and southbound traffic on Highway 95, the state’s major north-south route.
He also considered the alternative of asking residents to shut themselves inside their homes, shelter in-place.
“There’s going to be a certain amount of panic involved with either one of them,” Tyler said.
Thankfully, catastrophe—and panic—was averted.
Many people think of chlorine gas in relation to its use as a weapon in World War I, but it is used in hundreds of cities through the U.S. to treat both drinking water and sewage. Although many communities have switched to a safer treatment method— sodium hypochlorite or ultraviolet light—doing so involves greater costs.
Though the city’s supplier of chlorine is still working to determine why the chlorine tank leaked in the first place, Tyler was able to pinpoint why the initial effort to seal the leak was a failure.
Hazardous Materials teams used an “A-Kit,” or device designed to contain the leak, which fits over the top of the tank. When they arrived at the wastewater treatment plant, the kit wasn’t fully assembled.
Crews had to connect a valve to the A-Kit’s bonnet, or the piece that sits on top of a leaky tank.
The valve wasn’t a compression fitting, meaning it had no seal.
Though there was discussion about using Teflon tape or plumber’s “dope” to seal the connection, the manufacturer’s instructions didn’t specifically say to use tape or dope and the Haz Mat team was worried about possible reactions between the chlorine and other materials.
The chlorine, which is a corrosive, ate away at the threads in the fitting overnight.
When treatment plant worker Chris Wood arrived at the plant the next morning, he could smell chlorine through the door to the plant’s chlorine room.
Puzzled, crews again responded to the plant on Schweitzer Mountain.
Several options for addressing the leak were proposed throughout the day as Tyler contemplated what action to take if the situation escalated and the tank blew.
A conference call with representatives from the Department of Homeland Security and others didn’t provide Tyler with any clear direction.
He knew he had a decision to make, but felt he was lacking the information he needed—hard facts—that would lead him to a right decision.
Tyler called the supplier and asked if all of the chlorine tanks should be the same temperature. They said yes.
Using a thermal imaging camera, crews were able to determine that the leaking tank was 10 degrees warmer—confirmation that pressure was building.
Tyler knew then that pressure must be relieved and ordered crews to remove the A-Kit. The site was cordoned off until the supplier arrived to encase the leaky cylinder inside a coffin and remove it from the site.
Though the question of what caused the tank to leak remains, Tyler said the problem with the A-Kit has been addressed.
The manufacturer is changing their instructions and a new operating procedure is in place: All Hazardous Materials teams in the state are now carrying a 55-cent roll of Teflon tape.
Read about chlorine gas exposure here.
Photos courtesy of Robert Tyler