Dec 13, 2017

Memphis Repairs Sewer Main After Record Rainfall

Record rainfall in Memphis, Tenn. leads to installation of new sewer main

Sometimes, the different sectors of the water industry collide. In Memphis, Tenn., storm water and wastewater made an unwanted pair. In March 2016, a torrential downpour dropped 16 in. of rain on the city of Memphis over two days. Unprepared for such a storm event, the soil supporting a 96-in. sanitary sewer main eroded, damaging the sewer main.

This sewer main carries wastewater to the T.E. Maxson Wastewater Treatment Plant (WWTP) in Memphis. The damages amounted to nearly 40 million gal of raw sewage per day escaping into the Cypress Creek, which is near McKellar Lake and the Mississippi River.

Immediately, city officials activated an emergency response plan, which involved developing a turnkey bypass solution. The city hired Xylem Inc. to organize the solution and achieve the city’s goals, which included maintaining sewer services, minimizing environmental impact, ensuring regulatory compliance and repairing the main line.

“[The] key to the success of the project was the fact that the city of Memphis had a comprehensive emergency preparedness contingency plan in place,” said Ken Albaugh, regional director for Xylem’s Central Region, U.S. “Xylem was on site [and] able to go to work within a matter of hours from when we got the official ‘go-ahead’ for the bypass.”

In only six days, a team of nearly 200 people completed the project. With high demands—handling 160 million gal per day (mgd) at peak flow—this project was massive and included various stages. First, according to Albaugh, several critical path construction projects were required to support the bypass, including a road to the site and culverts to contain the bypass piping. In addition, a suction pit was created to hold the pumps. Additionally, crews installed a 36-in. bypass line to accommodate 11 mgd and relieve the structure of some flow.

The overall turnkey bypass included 16 pumps total and nearly 30,000 ln ft of high-density polyethylene (HDPE) pipe. Now, the sewer main can pump 60 to 160 mgd.

“We leveraged our familiarity with the sewer system and our extensive rental portfolio to come up with a safe, compliant and cost-effective turnkey bypass solution that maintained service levels for the city, while overcoming numerous obstacles—all within record time,” Albaugh said.

Though the crew had to work quickly in difficult terrain, the project provided an outcome that was better than expected.

“One of the benefits of Xylem’s turnkey solution is it allowed the city to focus our resources and our efforts entirely on design and construction and getting the pipe replaced,” said Paul Patterson, environmental engineering administrator for the City of Memphis. “And that was key.”

Albaugh added: “For me … no project was as challenging—or rewarding—as this emergency sewer bypass.”