The Jefferson Barracks Tunnel project is in final design and construction is planned to start in early 2017. The project area 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 system cannot handle during moderate to heavy rain. This will prevent overflows that would otherwise pollute our waterways.

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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. The estimated construction cost for the tunnel is $100 million.

Learn more details about the Jefferson Barracks Tunnel project by clicking on the fact sheet link below.

Jefferson Barracks Tunnel Fact Sheet – Spring 2016