City of Bridgeport Combined Sewer System Lining and Separation

When chronic combined sewer system backups and overflows were coupled with century-old infrastructure, the City of Bridgeport tasked D&B with the design and construction management of combined sewer system separation projects for five sewersheds. The projects would ultimately reduce the frequency of combined sewer overflow discharges to area waterways and were carried out in two phases—the first included the cured-in-place pipe lining of the combined sewer system and the second installed contiguous storm sewers that remove street runoff from the system.

D&B first verified existing sewer system components through a topographical survey and assessed the system’s condition and capacity through CCTV inspections, geotechnical investigations and hydraulic modeling. Upon an evaluation of the data, the system was found to be in relatively good condition and have only minor cracking and joint separations, Since the piping system was salvageable, it was determined to be most cost-effective to retain these pipes for the conveyance of sanitary waste.

A cured-in-place pipe lining system was recommended to enhance future integrity and eliminate groundwater infiltration, while the installation of a shallow stormwater drainage system parallels the existing combined sewers and collects roadway runoff from street catch basins. The storm sewer system connects into existing drainage lines that currently transport stormwater to area outfalls and, where the new system connects into existing outfalls, individual stormwater treatment systems were installed to remove debris and floatables prior to discharge.