Operators Kept Compliant Through South Carolina's 1,000-Year Flood

The wastewater treatment plant team in Columbia stayed on duty for two days through South Carolina’s 1,000-year flood and kept the effluent in compliance
Operators Kept Compliant Through South Carolina's 1,000-Year Flood
The plant experienced a 1,000-year flood from the remnants of Hurricane Joaquin, which brought as much as 25 inches of rain in the region and caused 19 deaths and $12 billion in damage.

When the National Guard can’t get to you, you know you’re in trouble.

Such was the case in October 2015, when historic rainfall left some of the staff at the Columbia (South Carolina) Metro Wastewater Treatment Plant surrounded by a raging river, a failing dike, and more than 7 feet of floodwater.

None of that kept them from staying on duty for two days to keep the plant running while crews manned lift stations to avoid adding raw sewage spills to the community’s problems.
The 1,000-year flood came from the remnants of Hurricane Joaquin, which dumped 15 to 20 inches of rain in the region and localized amounts more than 25 inches. Rain fell at up to 2 inches per hour; the Columbia airport reported 10.28 inches for Oct. 3-4, beating the old record by nearly 3 inches. The city set records for one- and two-day rains.

The flooding and storms caused 19 deaths and $12 billion in damage. According to the National Oceanic and Atmospheric Administration, the Columbia area experienced seven dam failures that rated Class C1 (may cause loss of life or serious damage) and 16 that ranked Class C2 (may damage infrastructure).

Yet the wastewater plant kept staff right on working as floodwaters rose around them. For their actions, Ashley Dove, Adrian Martin, James Foust and Brandon Wilcox received the Water Heroes Award from the Water Environment Federation. “We do love a challenge,” says Foust, chief operator.

Adds Dove, maintenance coordinator, “This is what we signed up for when we decided we wanted to do this as a career. We don’t really expect any  praise from it. We did what we hope anybody in this career would do. That’s to care for the environment and try to do whatever you can to keep an environmental catastrophe from happening.”

Rising tide

While the plant itself never flooded, it was threatened by the Congaree River. “We have a dike that protects us from the river, and the authorities didn’t know if it was going to hold with the river rising and a dam upstream being opened,” says Dove. “We had that on the river side, and then on the other side we had a creek with a dam breech and floodwater coming at us.”

There wasn’t much to do about the dike other than watch it. Eventually, it collapsed just downstream from the plant and flooded the surrounding farm fields. “Everything around us was flooded, and we were the only dry land,” says Foust.

At one point, the National Guard tried to get to the plant with a high-water rescue vehicle. “We could see that they had a couple of guys walking in front of their vehicle and they were up to their chins in water before they stopped and slowly retreated,” says Dove. As it turned out, the water reached more than 7 feet deep on the road.

Huge influent flow

Adding to the challenge was the flow experienced at the 60 mgd biological oxidation extended aeration facility. With an average flow of 35 mgd from its 60,000 customers over 120 square miles, the plant is designed for a peak flow of 120 mgd. During the peak of the storm, daily flows were 87, 120 and 156 mgd. “It was dicey, but we did it,” says Foust. “We sent some to the equalization basin for later treatment.”

With the high flows, no ability to bring in supplies or chemicals, and no way to remove biosolids, treatment of the wastewater had to be adjusted. “It took around-the-clock attention, but we met our discharge permits,” says Foust. All team members worked together instead of working in shifts: “We’d have guys working in the plant or a guy watching the SCADA, somebody would take a break, and somebody would fill in. We just rotated around and did it together. Nobody really slept.”

That went on for two days straight before the staff found a bit of somewhat dry ground where they could access the nearby Interstate highway. Dove recalls, “There was a little ditch, and we borrowed some rock from a neighbor so we could drive over it with our ATVs, climb the embankment and use the emergency lane for our vehicles to pick up and drop off people and get in supplies. It gave us a chance to get fresh bodies in and a chance to go home, get fresh clothes and a meal, and a good night’s sleep.” Dove had about 12 hours off over seven days: “I think I worked 160-something hours during the whole event.”

Dove’s duties included coordinating the field staff protecting the city’s 56 lift stations with capacities from 32 mgd to 200 gpm. “I watched the SCADA and directed them to evaluate the stations, make them do things they weren’t built to do because they normally are in automatic operation, and coordinate efforts if a station went down,” he says.

“Where we had a station with four pumps, it may be designed to have only three running. So we had somebody there to turn on the fourth pump. We had five maintenance technicians at the largest lift stations. They stayed until they felt it was unsafe, and they’d put it back in automatic and leave.”

What-if scenario

So, what would they have done had the plant been flooded? “We weren’t thinking of that at the time,” says Foust. “We’d have to go to plan C. We didn’t have a plan B. We thought about it after we saw what was around us.” The plant does have a few taller buildings where the staff could have taken shelter from high water.

As it was, the plant suffered relatively minor damage from external and internal flooding, though some equipment was destroyed by the high flows and debris. Problems continued for several months. “Sand coming in through the pipes ripped the guides off the traveling screens and knocked them out because we had a lot of washed-out lines,” says Foust. Other debris included bricks, PVC and pipe lining. Overflowing contact basins inside the plant also created sinkholes and gullies.

“One of the issues we’ve been having since the flood is a large amount of debris and sand passing through the plant,” says Dove. “We’re constantly having to bypass collapsed lines and get stuff fixed. Infrastructure was stressed before the flood, and it’s stressed tremendously after the flood.” The road into the plant was damaged and was not repaired until September.

Lessons learned

While actions during the event weren’t thoroughly planned, the staff did bring in a few provisions before the flood in case the incoming weather would cause problems getting people to and from the plant. “We purchased sandwich meat, popcorn, chips and stuff like that to just get by a day or two,” says Dove. “We lost potable drinking water at the plant, but we were lucky because I had two cases of water sitting in my office. We also had people reaching out to us after a couple of days wanting to send meals to us.”

He suggests plants with dike protection do regular inspections rather than assume that the structure will protect their plant: “Don’t say, ‘We haven’t had a problem, don’t worry about it.’ You never know when you’re going to need it.”

Even though the plant lost electrical power for just 30 minutes, Dove says the event prompted the staff to look at adding a source of backup power for the dual-feed system from the local utility. “We have a handful of lift stations that have backup power, but as we rehab the stations we’re making it a standard to put in backup power to keep them going.”

Records broken

The rainfall in the Columbia area on Oct. 3 and 4, 2015, broke the one- and two-day records, according to the National Weather Service. At the Columbia Metro Airport:

  • The one-day rainfall of 6.71 inches on Oct. 4 broke the old record of 5.79 inches set on July 9, 1959.
  • The two-day rainfall of 10.28 inches on Oct. 3-4 broke the old record of 7.69 inches set on Aug. 16-17, 1949.


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