7NT is excited to partner with Black and Veatch Corporation and The City of Columbus, Ohio on this project. This ongoing project will reduce/eliminate combined sewer overflows, which will improve the water quality and reduce the potential for human contact with waterborne pollutants by reducing overflows from the sewer system into creeks and rivers. 7NT is providing construction inspection services for the project (tunnel and near surface inspectors) as well as material testing services from our local certified laboratory.
The project includes a main tunnel of approximately 17,000 feet of 12-foot diameter tunnel at an average depth of 50 feet. This portion will be mined with a tunnel boring machine and constructed of precast concrete segments. There are also three main shafts. A 90-inch diameter microtunnel will also be constructed. A 36-inch relief sewer will also be constructed.