New tunnel system to eliminate sanitary sewer overflows and control combined sewer overflows in Hartford, Connecticut

The South Hartford Conveyance and Storage Tunnel is a major component of Hartford Metropolitan District's Clean Water Project. It is intended to capture and store combined sewer overflows from the southern portion of Hartford, CT, and sanitary sewer overflows from West Hartford and Newington, CT. The project is estimated to cost approximately $US500 M and will be constructed under multiple construction contracts. The project components include a deep rock tunnel 6.6 km long and 7.6 m excavated diameter, several kilometers of consolidation sewers, multiple hydraulic drop shafts with deaeration chambers and a 100 MLD pumping station for tunnel dewatering. The tunnel boring machine-bored tunnel will be excavated in shale, siltstone and basalt through several fault zones. An AECOM led team is currently performing the final design for the project.