Weathering the storm

Weathering the storm

How the Louisville Metropolitan Sewer District in Kentucky used flood pumps to remove 27 billion gallons of water after heavy rainfall.

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September 12, 2018
Hilary Crisan-Heavilin
Municipal Solid Waste

Natural disasters such as severe storms can cause roadways, homes and businesses to flood. While most municipalities have a flood plan in place for residents and business owners to stay safe during these dangerous occurrences, not all have systems in place to mitigate or clean up the resulting stormwater that pools after the storm has passed. Luckily for citizens of Louisville, Kentucky, the city was prepared when heavy rain and flooding hit central and southern states in late February.

According to a Feb. 27 CNN report by Amir Vera, at least three people died in Michigan and Kentucky from the flooding and rain. Other states, such as Arkansas, Louisiana, Oklahoma, Texas, Indiana, Missouri and Ohio, were similarly affected by the weather.

While residents in the Kentucky city were hit hard by storms and floodwater, the city avoided widespread damage thanks to the presence of its flood pumps. The city is surrounded by creeks and streams. When these creeks and streams are inundated with stormwater, floodgates equipped with pumps flow water back into the Ohio River.

With these floodgates in place, the city of Louisville was quickly able to start the cleanup process after the storms abated.

Pump it up

Marc Thomas, operations director for collections, flood protection and emergency response at the Louisville Metropolitan Sewer District, called the storm a “weeklong system” where the city experienced rain earlier in the week and flooding from the Ohio River later in the week because of storms that happened closer to Cincinnati that subsequently trickled down into Kentucky.

Some of the pump stations kicked into service before Feb. 23, when the large rain event occurred, and did not stop until March 8. Thomas says the pumps ran for as long as they did because the river was still receding through the first week of March.

According to the district’s website, the system protects more than 200,000 citizens, 87,000 homes and $24 billion in property throughout 110 square miles of Louisville. The system includes 29 miles of floodwall and earthen levee, 16 pumping stations, around 150 floodgates and 80 floodwall closures.

Thomas says some stations were built between 1951 and 1953 by the U.S. Army Corps. of Engineers, with others being built in 1981. Once the stations were constructed, the U.S. Army Corps. of Engineers turned them over to the city, and the district inherited them in 1987.

The pumps’ motors are manufactured by General Electric, Boston, and vary from 600 horsepower to 3,000 horsepower, with the largest pump generating 4,700 horsepower, Thomas says. According to the district’s website, gates can be closed where creeks and storm drains pass through the floodwall to keep the river from flowing up the streams, and the large pumps are used to lift the water from the creeks into the river. Additional gates and pumping stations keep the river from backing up through storm drains and pump the stormwater into the river.

Thomas says some pumps start automatically while others are programmed to turn a light on when the water gets to a certain height to notify service personnel. He says once the stations are in service, they must be manned around the clock.

The efforts to man the stations do not fall solely on the district and include volunteers throughout the agency that sign up to be on “flood pump duty.”

“For the duration of the flood, you may be assigned to first, second or third shift, and you go to live in this flood pump station for eight hours per day, and our flood protection is working 12 hours per day,” Sheryl Lauder, the district’s communications program manager, says. “It brings everybody together, that’s for sure.”

Working overtime

While the flood pumps were activated, standing water wasn’t a large presence after the storms. “Realistically, we got rain Feb. 23 and 24 and we were back down to normal in two days,” Thomas says. “We didn’t have water standing around people’s houses with the exception of the houses outside the flood protection system, and they were surrounded for no more than a couple of days.”

Despite the lack of standing water that needed to be cleaned up, nearly 27 billion gallons of water was pumped from the city and into the river, Lauder says. To process this quantity of water, pumps at all 16 stations in the city were in operation. The last time all stations were in service, according to officials, was in 2011.

Because of the pumps’ age, some went out of service while they were running and required repairs. Thomas says that while replacing the pumps would be ideal, it is cheaper to repair them, since the cost for replacement would be around $80 million.

Large amounts of debris, including a 6-foot-deep pile dubbed “trash island” gathered at the pumps. Bar screens, which Thomas says resemble placing a rake in front of a pipe, allowed the water to go through the pump and into the river without contamination. Large screens on the outside of the pumps filtered out bigger branches, and smaller ones caught smaller items such as tires.

Trash island, Lauder says, had a “variety of things in it,” including at least three full-size doors with frames; almost any kind of ball; dolls; and a full suitcase from a nearby homeless camp.

After the storm, the debris was hauled to landfill for disposal.

Being prepared

The district has a flood preparedness page available on its website with a list of tasks a resident should consult to make sure he or she can stay safe in the event of a flood. Some items include keeping a disaster supply kit, making emergency plans for family and pets, signing up for flood insurance and constructing barriers to stop floodwaters from entering buildings.

The district also issued a press release Feb. 26 with tips for safely cleaning up after the flood. These tips included checking for damaged power lines, gas lines, foundation cracks and other exterior damage before entering a home; contacting the fire department if confronted with a natural gas or propane smell or hissing noise; avoiding walking in a flooded basement because of the risk of electrocution; and turning off gas, water and electricity when possible.

Thomas and Lauder say area residents experienced property damage, but the assessment of damages is still ongoing.

Residents were required to have floodplain permits before repairing or rebuilding properties in a floodplain.

The district is currently gathering information for the Federal Emergency Management Agency (FEMA) on the flooding, but isn’t expecting financial relief anytime soon.

“We are gathering information right now as far as man-hours and receipts,” Thomas says of the FEMA funding. “We’re really in the initial steps. The last time we applied, it took a couple years before we got any money.”

The author is the assistant editor for Waste Today and can be contacted at hheavilin@gie.net.

Stormwater