Investigations and Mining the OARS Tunnel

April 10, 2014

The OARS Tunnel is a 20-foot diameter sewer tunnel being constructed for the City of Columbus to prevent combined sewer overflows from downtown Columbus entering the Scioto River. The tunnel will eventually extend from the Jackson Pike Waste Water Treatment Plant on the City’s south end to north to Interstate 670, just north of the Arena District. The tunnel is currently being mined through the bedrock nearly 200-feet beneath surface. Although yet to be completed, subsurface conditions have presented several challenges to the contractors while excavating the six access shafts, as well as the mining the first two miles of the 4.3 mile long project with a tunnel boring machine. A team lead by DLZ, conducted the subsurface investigations and designed the tunnel over a period of five years. These investigations strongly suggest that there would be unique conditions and challenges that would be faced during construction.