Eighteen stories underneath the Ohio River, construction crews are boring a gigantic tunnel to solve Louisville’s sewage woes.
The Metropolitan Sewer District has completed about 10 percent of a 4-mile-long tunnel meant to store excess sewage and stormwater, according to Jacob Mathis, project engineer.
The $200 million project is part of Louisville’s deal with the federal government to stop pouring raw sewage and stormwater into the Ohio River and Beargrass Creek.
The problem is the city’s wastewater treatment center doesn’t have the capacity to treat all of the sewage and stormwater that ends up in city sewers when it rains, so MSD dumps the overflow into local waterways.
The sewage is not only gross, it harms local aquatic life and can expose people to bad bacteria and pathogens.
The city originally planned a series of storage basins to deal with the excess sewage, but has since changed direction, said Mathis.
MSD spent about $4 million on construction of a basin near Grinstead Drive and Lexington Road before deciding to abandon the project in favor of extending the underground storage tunnel from 12th Street and Rowan Street to Grinstead Drive and Lexington Road.
The longer tunnel will have a greater storage capacity and will be more discreet than the additional basins, Mathis said.
“So it’s all below ground,” he said. “Under site, out of mind.”
Presently, the crew is working underneath the Ohio River east of 10th Street. They’re boring through ancient limestone using a 412-foot-long boring machine nicknamed “bumble bee.”
The bee can drill through 60 to 70 feet of rock per day, Mathis said. The rock is then loaded onto what is basically a “miniature locomotive” that transports it to the tunnel entrance where it’s removed 40 tons at a time.
When complete, the tunnel will capture 98 percent of sewage and stormwater overflows until it can be treated at the Morris Forman Water Quality Treatment Center and released into the Ohio River.
MSD expects the tunnel will capture about 439 million gallons of overflow during a typical year, Mathis said. That’s enough water to fill your bathtub about 5,400,000 times.
Mathis expects to complete the excavation of the tunnel by the end of the year, he said.