Lawrence Avenue Underflow Sewer System. Interim Report: Planning and Construction

摘要

A new and bold concept in design of urban drainage systems was developed as a step forward in the solution of combined sewer overflow problems. A deep tunnel in bed rock about 200 to 250 feet (61 to 76 m) below the surface was designed and constructed for the Lawrence Avenue drainage basin in Chicago. Utilization of modern tunnel boring machines made the project economically competitive with conventional sewers while reaping additional benefits of ease in construction, no disturbance to traffic and least inconvenience to public. In addition, the tunnel sewer will serve as a reservoir totally capturing smaller storms, and trapping a significant portion of the first flush of pollutants from larger storms. The entrapped pollutional load will be pumped to a treatment plant through a pumping station to be operated only at the end of the storm, for dewatering the tunnel. The project is expected to reduce, to a large extent, the combined sewer overflows to the waterways.