A giant drill driven by six 300-horsepower motors and using enough daily electricity to power 382 homes is digging a tunnel under Louisville. The machine is massive, and it’s part of a $200 million Metropolitan Sewer District project that is aimed at reducing the amount of sewage dumped into the Ohio River during heavy rainfall and avoiding fines from federal regulators.
The tunnel is meant to hold Louisville’s excess storm and wastewater. During dry weather, that water is treated at Louisville’s water treatment plant before it’s released into waterways, but heavy rainfall can swamp the facility and force MSD to dump untreated sewage water into Beargrass Creek and the Ohio River. The Waterway Protection Tunnel — one of many projects designed to reduce these sewer overflows — will stretch four miles under Louisville and measures 22 feet in diameter. When it’s done, it will hold up to 55 million gallons of overflow waste water until the water treatment plant is ready for the water.
“So instead of wastewater overflowing into our waterways, it’ll get treated and be put back into the Ohio River,” said MSD spokesperson Sheryl Lauder. “It’s a real win for the community and the environment.”
Drilling started in February, and officials gave reporters a tour of the tunnel on Thursday.
After locking about 10 of us into a sunshine-yellow, cylindrical cage, a crane picked the cage up and lowered us 200 feet down into the tunnel. Sloshing through mud and water, we climbed onto a small trolley which chugged through a mile and a half of tunnel under the city. A giant yellow tube rushed fresh air to the end of the tunnel, and a conveyor belt meant to shuttle rocks was idle along the tunnel’s wall. The drilling machine itself — nicknamed “Bumblebee in honor of Muhammad Ali — is longer than a football field and is expected to cut away 650,000 tons of limestone rock.
MSD started planning the project in 2015, 10 years after state and federal regulators entered into a federal consent decree to reduce the amount of sewage overflow MSD poured into the state’s waterways.
“The way [the tunnel is] designed,it has over a 100 year useful life,” said MSD Project Manager Jacob Mathis. “With the completion of this project, as well as the other project[s] MSD is doing, we will reduce our overflows by approximately 98 percent during a given year.”
Other projects include storage basins — such as the Clifton Heights storage basin and the Logan and Breckenridge Street Basin.
Mathis expects the excavation for the Waterway Protection Tunnel will be done in early 2020. The whole project, including cleanup and ensuring the tunnel is ready for water overflow, is expected to finish before the federal decree deadline of Dec. 31, 2020.