plum-island-DJI_0266 (copy)

Charleston Water System's Plum Island facility. Provided.

Enough untreated sewage to fill a backyard swimming pool has spilled from a pipe feeding Charleston's Plum Island Wastewater Treatment Plant and into a marsh creek on James Island.

The non-profit Charleston Waterkeeper group has cautioned people to stay out of nearby James Island Creek for at least three days after an estimated 7,200 gallons spilled Wednesday morning.

Charleston Water System, which runs the plant, will close a lane on Harborview Road at 9 a.m. Friday to make repairs.

Traffic will be delayed as cars will be stopped to share a single open lane.

Motorists said the smell is bad along the roadway. Business has slowed at the Ellis Creek Fish Camp nearby because the work is disrupting traffic, said Samantha Tretsven, a server. But the leak couldn't be smelled from there, she said.

The thousands of gallons spewed from the line after a rupture. The leak lasted more than an hour, until a crew shut off a valve to the main, said Michael Saia, CWS spokesman. Vacuum trucks sucked up about 1,200 gallons from standing pools.

"This is a force main. It's under a lot of pressure. So it likely wasn't leaking very long before it was noticed," Saia said.

The S.C. Department of Health and Environmental Control has been notified of the main break, spokeswoman Laura Renwick said.

"The utility responded, stopped the discharge, vacuumed up residual and is repairing the line," she said. "Once the repair to the line is complete, the utility will conduct sampling and provide a required report to DHEC for the Department to review."

Renwick did not say whether CWS could be cited or fined for the leak.

State Sen. Sandy Senn, R-Charleston, who lives in the area, contacted DHEC about the leak and said she would call on the agency to enforce the regulations and have CWS mitigate for the pollution.

"'Sorry' just is not enough, especially at that creek, which has not been meeting federal water quality standards," she said.

Andrew Wunderley, of Charleston Waterkeeper, called the pollution a huge concern.

High levels of fecal bacteria — human and animal waste — have already been routinely recorded in the creek and others that surround the harbor. The water quality in the estuary has been deteriorating for years, while the monitoring has fallen off and efforts to maintain it for fishing or swimming aren’t stopping the degradation, studies have indicated.

"We’ve been testing bacteria levels and working to clean up James Island Creek for years. A spill of the this magnitude directly into a creek already suffering from high bacteria levels is a public health threat for everyone, especially those that live near and use the creek," Wunderley said.

The state's Total Maximum Daily Load plan for dealing with fecal bacteria in the creek specifically excludes sewage overflows and spills as a pollution source, he said.

"DHEC needs to step up its overflow and spill enforcement across the board, and Charleston Water System needs to come to the table and get involved in the effort to clean up James Island Creek," Wunderley said.

The main is only a minor feed to the plant, which also pulls from collector tunnels. It routinely would feed 180,000 gallons per day. The plant takes in about 24 million gallons, according to CWS.

Trucks on Thursday were collecting sewage from the valve and carrying it to the plant for treatment.

CWS couldn't immediately determine what caused the leak, Saia said. Possibilities range from flaws in the pipe itself to shifts or vibrations in the ground.

"We do know that it wasn’t exterior corrosion. The pipe was wrapped in protective material and did not show any signs of corrosion," Saia said.

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Reach Bo Petersen at @bopete on Twitter or 843-937-5744.

Science and environment reporter. Author of Washing Our Hands in the Clouds.

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