Rehabilitation Technologies to Abate Infiltration in Sanitary Sewers

Abstract

In urban coastal environments, sewer infrastructure is plagued by infiltration which seeps into aging and compromised pipes. Infiltration increases pumping costs, reduces treatment efficiency, and may trigger release of partially treated wastewater at water reclamation facilities. This study analyzed infiltration in a small urban sewershed in Pinellas County, Florida to assess the magnitude of the problem. Flowmeters were deployed in different sections of the sewershed during 2015 and 2016 to evaluate spatial and seasonal variabilities in infiltration. To abate excessive infiltration, three trenchless sewer rehabilitation technologies were applied in 2019, and the flowmeters were redeployed in 2021 at the same locations to compare pre- and postrehabilitation conditions. The applied technologies were joint grouting, expanded-in-place PVC lining (EX liner), and cured-in-place pipe (CIPP). Pipe rehabilitation reduced infiltration by 43% during the dry season and by 49% during the wet season, but effectiveness varied by technology. Data revealed that CIPP and EX liners were not as effective as joint grouting, probably because groundwater seeps into the space between the pipe and liner and at lateral connections.