The Jefferson Barracks Tunnel project is in South St. Louis County, extending from south of I-255 at Koch Road to the Lemay Wastewater Treatment Plant located at the confluence of the River Des Peres and the Mississippi River. The tunnel and related projects will replace the current aging system, adding capacity to collect, transport, and store wastewater that the existing system cannot handle during moderate to heavy rain. This will prevent overflows that would otherwise pollute our waterways.  The tunnel will stretch 17,800-feet long when completed.

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The Jefferson Barracks Tunnel runs through a well-known area of river bluff karst. Karst describes limestone that may include caves and sinkholes as a result of erosion. Design efforts included identifying the best alignment for the tunnel to avoid costly construction through these sinkholes and caves. These efforts, including geological borings, were taken to locate possible locations for the tunnel options. The best choice was to go below the limestone and karst and tunnel into rock at 150 feet to 230 feet below the surface.

 

To see photos from the install of the Tunnel Boring Machine into the tunnel shaft, click here.

 

Learn more about the Jefferson Barracks Tunnel project and see updates at the links below:

Jefferson Barracks Tunnel Construction Update – Fall 2018

Jefferson Barracks Tunnel Construction Update – Summer 2018

Jefferson Barracks Tunnel Construction Update – Spring 2018

Jefferson Barracks Tunnel Construction Update – Winter 2018

Jefferson Barracks Tunnel Construction Update – Spring 2016