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Collection Systems O & M Fact Sheet Trenchless Sewer Rehabilitation

As the infrastructure in the United States ages, increasing importance is being placed on rehabilitating the nation’s wastewater treatment collection systems. Cracks, settling, tree root intrusion, and other disturbances that develop over time deteriorate pipe lines and other conveyance structures that comprise wastewater collection systems. These deteriorating conditions can increase the amount of inflow and infiltration (I/I) entering the system, especially during periods of wet weather. Increased I/I levels create an additional hydraulic load on the system and thereby decrease its overall capacity. In addition to I/I flow, storm water may enter the wastewater collection system through illegal connections such as down spouts and sump pumps. If the combination of wastewater, infiltration, and illegal storm water connections entering the wastewater treatment plant exceeds the capacity of the system at any point, untreated wastewater may be released into the receiving water. This bypass of untreated wastewater, known as a Sanitary Sewer Overflow (SSO), may adversely affect human health as well as impair the usage and degrade the water quality of the receiving water.