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Greenville wastewater tests consistently show 'major' levels of coronavirus in population

ReWa facility on Mauldin Road

The Renewable Water Resources wastewater facility on Mauldin Road south of Greenville is one of the largest in the region. Ryan Gilchrest/Staff

GREENVILLE — Wastewater flowing into the region’s biggest sewer treatment facility on Mauldin Road in Greenville is loaded with evidence that the spread of coronavirus is widespread in the region and not yet going away. 

Data shared Tuesday with The Post and Courier showed that all 14 samples of wastewater taken since June 8 showed a “significant” to “major” level of COVID-19 infection in the general population. 

The Mauldin Road wastewater treatment plant handles about 15 million gallons a day and is among the largest such facilities in the region. It serves the central, urban core of Greenville County, starting with Travelers Rest to the north, collecting nearly all of the city of Greenville’s sewage, including downtown, and continuing to collect and pipe sewer water south toward the plant near Interstate 85.   

Greenville coronavirus sewer graphic

Greenville's regional sewer authority, Renewable Water Resources (ReWa) released this data Tuesday, July 28, 2020, showing evidence of community spread of coronavirus. Clemson professor David Freedman has said that any measure above 100,000 virus copies per liter is a significant concern. Provided

David Freedman, an environmental engineering professor at Clemson University, has been tracking similar wastewater data for the Clemson area since late May and helped Greenville’s regional sewer utility — Renewable Water Resources, or ReWa — interpret the data coming out of the Mauldin Road facility.

Levels of concern about community spread of disease, Freedman said, increase by orders of 10, starting with little to some concern so long as copies of the coronavirus remain below 100,000 per liter of wastewater. The first sample taken at Mauldin Road on June 5 was well below that, sitting at just 5,000 copies per liter. Still, Freedman said, anything between 4,000 and 10,000 suggests to scientists that “something big is about to happen.”

“At that point had the area done something with respect to a mask ordinance or closing bars or just implementing common sense things to mitigate people's face-to-face contact, they could have avoided that,” Freedman said of the coming outbreak.

Within three days, on June 8, wastewater readings at Mauldin Road shot up to 310,000 copies per liter and have stayed above 100,000 ever since. Four times readings pushed above 1 million, most recently on July 20.

This is data that board members of ReWa learned on Monday from Cameron Colby, a Clemson University environmental engineering graduate student interning this summer at ReWa. Freedman is Colby’s faculty advisor. 

Colby’s presentation has not yet circulated among city or county political leaders who could institute social distancing measures.

Environmental engineers and epidemiologists acknowledge they are covering new territory and are as yet not completely certain how to interpret coronavirus data going forward. Wastewater-based epidemiology research is a decades-old field for diseases such as polio, but its application to coronavirus dates back only to the spring when scientists in Europe started testing sewer samples. 

“We must understand and learn along the way,” said Chad Lawson, ReWa’s spokesman. “It’s a learning process that’s transparent and in the public space. Normally you will undertake research, go through a peer review process and then you publish the results. In this sense, what you’re doing is maybe writing a chapter, or writing a draft of a chapter, and releasing that.”

Freedman said no one is sure how long coronavirus lingers in the human body and continues to be shed into wastewater once symptoms have passed. But, he said, breakthroughs are imminent. With his data on three Clemson area wastewater treatment plants in hand, he said, he hopes to soon measure the relative impact of a citywide mask ordinance that City Council members there passed in late June.

What is better understood, he said, is the effectiveness at wastewater testing on predicting outbreaks to come. Coronavirus is undetectable once it falls below 4,000 copies of the virus per liter of wastewater. Once it creeps above this line, however, policy makers appear to have up to two weeks' notice of an outbreak.

Colby said part of the Mauldin Road plant’s service area is Clemson University’s International Center for Automotive Research at Interstate 85 and Laurens Road. Also included is the university’s MBA program in downtown Greenville. Clemson University, she said, has created a “dashboard” of data points from multiple locations, including Greenville, Pendleton, Anderson and Seneca — places known to house students and employees — to determine the risk of a coronavirus outbreak among all campus facilities. Students will start returning to dorms in Clemson on Sept. 13, but off-campus students and employees are already returning to the area.

“We are on that dashboard,” Colby said.

ReWa spokesman Chad Lawson said the utility would continue collecting coronavirus data from wastewater through the end of the year.

Follow Anna B. Mitchell on Twitter at @AnnaBard2U.

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