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Drilling phase of the Jefferson Barracks Tunnel reaches completion

Sean Stone
Metropolitan St. Louis Sewer District
The Metropolitan St. Louis Sewer District completed the drilling phase of the Jefferson Barracks Tunnel. MSD used a tunnel-boring machine to complete the drilling process.

The Metropolitan St. Louis Sewer District has hit a significant milestone and has finished drilling the Jefferson Barracks Tunnel.

When fully completed, the seven-foot-diameter pipe will run up to 220 feet underground for more than three miles from northern Oakville to the confluence of the River des Peres and Mississippi River.

The $155 million tunnel system will allow MSD to take wastewater out of the older pipelines to prevent backups, said Metropolitan St. Louis Sewer District representative Sean Stone.

“It's been in need for a long time,” Stone said. “The network of pipes and pump stations that are there right now are old and inadequate.”

Many of the current pipes are up to 60 years old, too old to keep up with current demand, Stone said. The new tunnel will take wastewater from some of the older pipes and pump it into the Lemay Wastewater Treatment Plant.

MSD aims to complete the tunnel by spring 2024. The sewer district worked with a variety of contractors to dig the tunnel, including Goodwin Brothers and Williams Tunneling.

O’Fallon, Mo.-based SAK Construction used a tunnel-boring machine to dig. Stone said the firm and MSD will remove the machine from the tunnel before adding a fiberglass pipe, grout and concrete to complete the main tunnel. Once that's completed, MSD will start on a pump station that will operate the tunnel, which is expected to be completed in 2026.

The tunnel and pump station are expected to hold about 15 million gallons of storage, allowing MSD to throttle the amount of water coming into the Lemay plant.

“So much of the work we've been doing, really, as long as we have existed, but especially in the past 10 years, is aimed at reducing those overflows and those backups which leads to a cleaner water supply and a cleaner environment,” Stone said.

Chad is a general assignment reporter at St. Louis Public Radio.

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