CSO Long-Term Control Plan
Des Plaines River Tunnel

About This Project

At first glance, the project seemed fairly routine: build an 865′ tunnel, 111.5″ in diameter, underneath the Des Plaines River. However, due to the fact that the river was channelized in the 1920s, the eastern shaft elevation was lower than the elevation of the river. Because of this, if any water from the river made its way into the tunnel, there would be potential for flooding on a large scale.

Recognizing this risk, the City of Joliet worked with the contractor and Midwest Mole to develop a unique pilot-bore approach, in order to verify the ground conditions along the tunnel route. This was to ensure that the tunnel could in fact be constructed without the risk of flooding. After gaining peace of mind, the tunnel was then successfully bored, improving the water quality of Joliet, IL.