The goal of the Department’s Sewer Rehabilitation Program (SRP) is to investigate, identify and correct failing sewer infrastructure in order to increase system capacity and insure the life of its assets.
The Brentwood Water and Wastewater Department’s ongoing SRP program dates back to the early nineties. Activities to rehabilitate sewer pipelines and manholes included line inspections via closed circuit video and point repairs with chemical grouting. However, beginning in 2006, the SRP program was redefined and expanded to fulfill requirements of an Agreed Order issued by the Tennessee Department of Environment & Conservation.
The redevelopment of the program now includes a comprehensive, $30 million dollar corrective action plan that extends through the year 2015 and is aimed at eliminating sewer overflows by reducing storm water infiltration into the sewer system through pipeline and manhole rehabilitation and repair.
The programs approach is to identify problematic areas and prioritize rehabilitation tasks through system flow monitoring and video inspection. Projects to be completed by private contractors during the multi-year program include, rehabilitation of approximately 100,000 linear feet of trunk and collection sewer lines primarily by relining pipes and manholes and an upgrade to the Department’s sewer pumping station to increase capacity.
Pipe “relining” was selected as the primary rehabilitation method because of its minimal impact to above ground property. Pipelining is mostly a trenchless process and therefore less destructive to the surrounding above ground property. The contractor installs a felt or fiberglass based liner through an existing manhole and into the underground pipeline that is being rehabilitated. Air is typically then applied to inflate the liner and then the liner is cured via ultraviolet light or hot water. Once cured in place, the new liner seals up all cracks and points of infiltration and future surface or ground water is prevented from entering the section that has been rehabilitated. The rehabilitated pipe has a new life expectancy of approximately 50 years.
PROJECT UPDATE (Updated January, 2015):
To date, the Department has eliminated an estimated 700+ million gallons of infiltration and inflow resulting in a reduction of sewer overflows and operational cost. Work is on hold until phase four is planned. This work is anticipated to include continued lining of individual service laterals and manholes in areas of town which will be determined based on further evaluation of flow data by the City's engineers.