Editorial: Gas leak could have been major disaster for Chattanooga

Chlorine scare points up need for safety review

Wearing hazmat suits, members of the Chattanooga Fire Department enter the Moccasin Bend Wastewater Treatment Plant on Sunday, Mar. 15, 2015, in Chattanooga to shut off a chlorine tank leak.
Wearing hazmat suits, members of the Chattanooga Fire Department enter the Moccasin Bend Wastewater Treatment Plant on Sunday, Mar. 15, 2015, in Chattanooga to shut off a chlorine tank leak.

Chattanooga dodged a potentially deadly bullet Sunday and Monday.

Sometime near 6 p.m. Sunday, chlorine began to leak from a one-ton cylinder in the chlorine building of the Moccasin Bend Wastewater Treatment Plant, and workers called 911. The Chattanooga Fire Department soon arrived with several fire companies and the hazardous materials team.

The building has safety equipment called "scrubbers," which converts the chlorine into a harmless water vapor, but one of the scrubbers later malfunctioned and became overheated.

Two treatment plant workers were overcome and taken to the hospital. Firefighters with the haz-mat team put on encapsulated suits, made their way into the chlorine building and successfully stopped the leak at about 7:40 p.m. Sunday night. Because the leak was contained, no evacuation was necessary. But that might not have been case in slightly different circumstances.

In January 2005, a train accident and derailment in Graniteville, S.C., led to the rupture of tank car carrying chlorine gas. Nine people died -- all but one was killed by inhaling chlorine fumes. Another 500 were treated for chlorine exposure and 5,400 residents within a mile of the crash were forced to evacuate their homes and businesses for nearly two weeks while hazardous materials teams decontaminated the area.

photo Wearing hazmat suits, members of the Chattanooga Fire Department enter the Moccasin Bend Wastewater Treatment Plant on Sunday, Mar. 15, 2015, in Chattanooga to shut off a chlorine tank leak.

In 2007, a chlorine dioxide leak at the Rock Hill, S.C., water filtration plant prompted a nearly nine-hour evacuation of about 1,500 people from their homes and businesses after between 4 and 25 pounds of chlorine dioxide gas leaked from a device that pulsates small amounts of the chlorine mixture into the water as a disinfectant. No workers were inside the equipment building where the leak occurred, and one was injured, according to wire reports from the time.

In 2009 alone, chlorine was involved in 181 reported accidents, according to a public accessible government database called the Hazardous Substances Emergency Events Surveillance.

Environmental Health News in 2011 reported the Agency for Toxic Substances and Disease Registry had found that chlorine releases in fixed facilities resulted in victims and evacuations in more industry categories than any other substance.

The Center for Effective Government, formerly OMB Watch, states that more than 2,700 facilities nationwide currently store large amounts of toxic chlorine gas, putting millions of Americans at risk -- even while the use of that chlorine, handled correctly, also keeps us safe. In the past 15 years, over 600 accidents injuring almost 800 people have occurred at these facilities. However, according to the group, in some cases safer alternatives are available.

We normally think of chlorine as that sanitizing material in bleach or as the germ-fighting chemical we keep in swimming pools but chlorine is a strong and deadly gas or liquid that when not carefully monitored as the cleanser that treats wastewater before it is released to the Tennessee River or as the additive to sanitize our drinking water, also can be our worst nightmare. For obvious reasons, the wastewater treatment plant and the water treatment plants have enormous stores of the chemical.

Unlike rail cars, water and wastewater plants have safety systems. We're glad for that. But we should hope there will be follow-up investigations to determine when and how the safety systems at Moccasin Bend are tested and verified. When was safety equipment -- like the chlorine scrubbers -- last inspected or repaired? The accident, as well the the malfunctioning and overheating scrubber, could have had very tragic consequences.

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