Contact Mayor Cogswell and Councilman Waring and ask them to put Plum Island at the top of their agenda for infrastructure.

Mayor William Cogswell  

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Councilman Perry K. Waring
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Poop water on the rise as Debby causes leak at Charleston sewage treatment plant

• By Teri Errico Griffis and Komlavi Adissem te*******@po************.com ka******@po************.com
• Aug 6, 2024

Plum Island is no stranger to water leaks when the tides are high and the rain is deep, but the impacts of Tropical Storm Debby have led to sewage spillovers into marshes and creeks.

The Plum Island Wastewater Treatment plant, one of the largest sewer plants in South Carolina, is located on a 22-acre island in the Charleston Harbor. For 50 years, raw sewage from West Ashley, James Island and other areas has been treated there.

But the plant can only hold so much water. Typically, Plum Island sees about 25 million gallons a day, said Mike Saia, spokesperson for the Charleston Water System. On Aug. 6, the plant was inundated with 95 million gallons, leading to two leaks.

The first spillover of the morning, which saw partially treated wastewater spill into Dill Creek, stopped overflowing as of 2:30 p.m., Saia said. He did note that the leak could return at the next high tide.

“Whenever the area gets a heavy rain, coinciding with a high tide, all that massive amount of stormwater that infiltrated the sewers heads to Plum Island,” Saia said.

When high tide comes in, treated wastewater is typically released into the shipping lane. But when major rainstorms compound, they put pressure against the flow coming out of the plant and into the harbor, Saia said.

“When it then gets some resistance, it backs up and just happens to back up at one point in our plant every time,” he said. “When these conditions are present, it overflows.”

A remedy is in the works to upgrade the plant’s effluent pump station that can withstand extremely high tides and rainstorms mixed together — but the execution is still three to five years out.

Plum Island is currently in the midst of a $110 million capital improvement project at the site where the the new effluent pump station would be located. Until the project can kick off, the current solution is to let the tide roll out and the rain subside.

As CWS monitors the somewhat routine overflow, Saia said a second leak has since sprung in another location. This one for the first time.

“This is wastewater that’s much earlier in the process,” he said, though he is unsure what exactly is causing this particular overflow. 

“It’s absolutely attributed to the high flow, but this isn’t the first time we’ve had flows of this magnitude before,” Saia added.

The water is coming from the plant’s primary clarifiers, releasing wastewater on the side of Plum Island that faces a small unnamed creek. The unnamed creek is directly adjacent to James Island Creek. 

Andrew Wunderley, executive director of Charleston Waterkeeper, said that the wastewater that leaked from the plant is, simply put, disgusting.

“It’s not fully treated sewage. So poop water from homes, businesses and wherever else goes to the Plum Island treatment plant to be treated before it’s discharged into the harbor,” he said. “But in this case, because of all the rainwater and floodwater that’s gotten into the sanitary sewer system, the treatment plan is overwhelmed, and that partially treated sewage is spilling out of of the plant into the marsh and the harbor there where it’s located.”

Wunderley said that untreated sewage is full bacteria and pathogens that can cause everything from ear, nose and throat infections and the stomach flu to serious diseases like cholera and tuberculosis.

He added that these health risks are why it is crucial for people to avoid the area until it is confirmed to be safe again after testing.

“What they’ll be testing for is enterococcus bacteria, and that’s a species of bacteria that’s highly associated with the intestines of warm-blooded animals, namely you, me and everybody else,” Wunderley said.

He said that when the measurement is about 104 colony-forming units per milliliter, that is a sign that pathogens are present in water and the risk of illness is greater. He noted that while the state’s level is set at 104 units per milliliter, a typical monthly average can be as low as 35 units per milliliter.

Wunderley emphasized that this is far from the first time that wastewater from the plant has spilled over into nearby waterways. A review of the CWS account on X showed four public notices for sewage spillovers this year, including the two brought on by Tropical Storm Debby. A fifth occurred in mid-December 2023.

Charleston Waterkeeper, represented by the Southern Environmental Law Center, had previously threatened legal action against CWS for the pollution in Charleston waterways caused by leakages and system failures.

Regarding the Aug. 6 leaks, though, CWS does not know the level of impact on the James Island Creek because they’ve yet to calculate the amount of flow that’s occurred.

“What you may see in upcoming Charleston Waterkeeper testing is an increase in their bacteriological testing there at the James Island Creek — or you may not,” Saia said. “It’s an unknown right now.”

The CWS has background samples for the water, so Saia said in a few days when the overflows subside, he’ll go back and test the harbor and unnamed creek. 

He suggested following along with social media. The CWS will confirm when the waters have returned to recreational standards and can be used by the public.

Wunderley expressed that people should try their best to avoid contact with floodwaters and stormwaters in general.

“The floodwater is horribly polluted. It’s about the dirtiest water that you can imagine,” he said. “It’s got high levels of bacteria, pathogens can be present. It’s got pesticides, herbicides, gas and hydrocarbons, trash, debris, you name it. Anything that’s on the ground can end up in the water and in floodwater.”

Anyone in the city of Charleston who sees an overflowing manhole should call 843-727-6800 and Charleston Water System will come out to investigate.