Rock Hill officials are blaming a cracked pump for a chlorine gas leak that forced the evacuation of more than 500 homes on Monday.
The leak, which occurred inside the city's water treatment plant at Cherry and Mount Gallant roads, stranded dozens of business owners, closed two major traffic arteries and stirred fears that the plant might need to be temporarily shut down.
But a team of inspectors found Monday afternoon that no chlorine dioxide fumes escaped the building -- and the public was not in any immediate danger.
It wasn't clear what caused the crack, but utilities officials met late Monday with the manufacturer to begin figuring it out. The pipe is housed in a new section of the plant that had been in operation for five weeks, said Utilities Director Jimmy Bagley.
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An automatic sensor went off at 4:05 a.m. Monday alerting a plant worker of the problem. The worker then notified the Rock Hill fire department. About 40 minutes later, firefighters had cut off power to the facility, stopping the flow of chlorine.
'Very potent gas'
Bagley estimates the leak lasted for about 45 minutes, resulting in less than a pound of chlorine escaping. Chlorine is added to water as a disinfectant.
"Chlorine is a very potent gas," Bagley said. "It's a great tool for disinfection. That's what it's used for. But just like it kills all those microbes, if it's used improperly, it can be a hazardous material."
Not knowing whether any gas had seeped outside, responders decided to evacuate neighbors, shut down parts of Cherry Road, Mount Gallant and Eden Terrace and keep area employees from driving to their workplaces Monday morning.
Police scanners buzzed with chatter from emergency crews for much of the morning.
"Worst case, it could've been that we had a release of an airborne poison that got into people's ventilation systems," said Cotton Howell, director of York County Emergency Management. "That was very minimal, but we tried to make sure we had the resources in place. I would not have wanted to sit here and say, 'We didn't go as far as we could have.'"
Responders used the reverse 911 system to notify some 530 homes -- or about 1,500 residents -- in the immediate area. The city and York County Emergency Management informed the Department of Homeland Security and stayed in touch with the National Weather Service to keep apprised of changes in wind currents.
"Precaution is the order of the day," City Manager Carey Smith said at a morning news conference. "Trying to be ahead of the curve rather than react is what we're trying to do."
The American Red Cross set up an emergency center for displaced residents at Boyd Hill Recreation Center. About 20 people, almost all elderly, were at Boyd Hill around noon.
Leak contained to building
By 1:20 p.m., inspectors determined that the leak no longer posed a threat because it was contained to the building. Residents were allowed to return home.
"Looking at it now, it looks like it was a lot of extra work," Bagley said. "But I think it was necessary."
Nearby roads re-opened in time to prevent what would have likely been major traffic snarls Monday afternoon as thousands commuted home from Charlotte.
City officials initially feared that repairing the faulty pipe could require shutting down the plant.
In that case, the city would have turned to its reserve supply: Three million gallons of water stored in underground tanks beneath the facility. Smith made clear that's not a step the city wanted to take.
The plant, built in 1950, recently underwent the most extensive renovations in its history. Bigger pipes and a third 1 million gallon storage tank were installed to increase its capacity to 36 million gallons a day, up from the previous level of 24 million gallons.
Rock Hill sells water pumped from Lake Wylie to Fort Mill, which in turn sells water to York County, which sells to Carolina Water Service, which serves parts of Tega Cay. The city of York recently joined the customer list.
Buying from Rock Hill prevents local municipalities from the costly burden of having to treat their own water.