Fall River CSO tunnel and shaft system

The paper presents the benefits of using underground space to provide the most economic solution for minimizing CSO problems and reducing flooding while supporting the potential to revitalize the economy of the City of Fall River, Massachusetts. The CSO tunnel has been positioned to virtually eliminate the requirements of tunnel lining and ground support. For the efficiency of CSO capture, some of the drop shafts are located in Rhode Island formation or weathered rock. The topography of the City and shallow overburden was used in designing the tunnel profile to convey the flow by gravity, thus eliminating the need for pumping of dry/wet weather flow. In addition, the collection system between the tunnel and the water front has been modified to separate overland storm sewers from the sanitary sewer system to revitalize the town in a cost effective method.