Cleanwater Nashville

Metro Water Services

News

Additional updates

Smoke testing yields clues for system repair

Date added: 26-Aug-2015 07:35 AM

Smoke testing yields clues for system repairCLEAN WATER NASHVILLE USES A VARIETY OF TECHNIQUES to assess the condition of the underground sewer system. One of those techniques, smoke testing, is a low-tech method, but can be effective at identifying potential defects in the system.
[read more...]

Natural setting shapes repair approach

Date added: 26-Aug-2015 07:33 AM

Natural setting shapes repair approachDAVIDSON COUNTY’S SURROUNDING environment is an ever-present factor in how the Clean Water Nashville Program plans construction repairs on aged and defective wastewater infrastructure.
[read more...]

East Nashville rehab projects continue in Inglewood and Jackson Park neighborhoods

Date added: 26-Aug-2015 07:31 AM

East Nashville rehab projects continue in Inglewood and Jackson Park neighborhoodsCOMPREHENSIVE SEWER SYSTEM RENEWAL throughout large areas of East Nashville and Inglewood continues with the start of the Shelby Park Rehabilitation—Area 4—Brush Hill Road project.
[read more...]

New program website expands public access

Date added: 26-Aug-2015 07:27 AM

New program website expands public accessCLEAN WATER NASHVILLE HAS LAUNCHED A NEWLY DESIGNED WEBSITE that provides easier navigation, expanded public resources and improved tools such as an interactive map to provide citizens access to information about this important program. The website was redeveloped based on feedback provided by representatives from Metro Water Services, public and private partners and participating stakeholders.
[read more...]

Cured-in-place pipe lining seals the deal

METHOD IS ALTERNATIVE TO DIGGING IN STREETS

IN THE DECADES FOLLOWING INSTALLATION, the pipes and manholes that make up Nashville’s system deteriorate, resulting in cracks and other defects along the pipe and at pipe joints. These defects allow excess rain or groundwater, known as infiltration and inflow, to enter the sewer system and can lead to sanitary sewer overflows. To combat this problem, the defective pipes can be unearthed and replaced, which can be quite disruptive, or they can be repaired in place through sewer system rehabilitation.

Cured-in-place pipe (CIPP) lining is one of several sewer rehabilitation methods used to repair leaking or structurally unsound existing pipelines. Little to no digging is involved in this trenchless process, making for a more cost-effective, environmentally friendly process that is completed more quickly and with fewer impacts and disruptions than pipe replacement. CIPP is the primary sewer pipe rehabilitation method used by Metro Water Services (MWS) since the early 1990s. CIPP results in a seamless, tight-fitting, corrosion-resistant liner within the original host pipe that improves pipe hydraulics and restores the pipe to a structurally sound condition.

CIPP consists of a flexible felt tube which is saturated with gel resins. The cured-in-place pipe liner is stretched inside the defective pipe between two manholes. After the liner is placed inside the pipe, the resins within the liner are activated, typically using recirculated hot water or steam from a boiler truck. This creates a chemical reaction that converts the flexible felt liner into a rigid, solid pipe that adheres to the interior of the defective host pipe, resulting in a new pipe within the old pipe.

After the CIPP curing process is complete, which may take from a few hours for small diameter pipes to 24 hours or more for large interceptors, the connections for service laterals to homes or businesses are restored internally using a robotically controlled cutting device. Typically a new access location (cleanout) is installed at the property line unless surface features make excavation difficult. Depending on the location of the service lateral, the portion of the service line between the property line and the main sewer line may be rehabilitated through CIPP or replaced through excavation.

CIPP requires diversion pumping of the sewer flow in the existing pipeline while the liner is being installed. This may involve temporary pumps and pipes on the top of the ground from the upstream to the downstream manholes. For larger diameter pipes, preparing the pipe for lining may take longer than the actual lining process. A number of trucks and some large equipment are required to perform the work, and temporary access roads in easements may be necessary.