Cleanwater Nashville

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Additional updates

Washington CSO Control Facility goes online

Date added: 11-Aug-2015 09:35 AM

Washington CSO Control Facility goes onlineA major combined sewer facility providing optimization for wet weather storage, screening and control of floatables and solids went online in April of this year. In addition to providing treatment, the facility dramatically reduces the number of overflows at the Washington outfall, and reduces the volume of overflows by approximately 90 percent annually.

Constructed at a cost of approximately $17 million, it was operationally complete in time to meet the Consent Decree milestone.
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Update on the Metro Nashville Consent Decree Program

Date added: 11-Aug-2015 09:34 AM

Update on the Metro Nashville Consent Decree ProgramOn August 6, 2012, Scott Potter and Ron Taylor of Metro Water Services provided an update on the Clean Water Nashville Overflow Abatement Program program to the Metro Council. This presentation addressed the status of the Consent Decree and planned projects included in the Long Term Control Plan for Metro Nashville Combined Sewer Overflows (Long Term Control Plan update) and the Corrective Action Plan/Engineering Report.Click here to download a copy of the presentation.
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Remote-controlled cameras provide eyes for underground pipe repairs

The majority of Nashville’s sewer system lies hidden beneath streets and buried in easements. Since it cannot be readily observed, Metro Water Services (MWS) deploys a variety of technologies to assess the system’s condition.

One of those technologies, known as closed circuit television (CCTV) inspection, involves viewing the inside of a pipe via a remotely-operated camera in the sewer. The camera, typically installed on a small wheel-based chassis, records video as it travels down the pipe. The video can be viewed in real time by the operator or saved for future evaluation.

CCTV inspection is a fundamental tool utilized by MWS and the Clean Water Nashville Overflow Abatement Program (CWNOAP) to assess the condition of the sewer system, including:

  • Confirming pipe material, pipe size, and location of service laterals
  • Locating obstructions such as roots, grease, or debris that may require cleaning
  • Identifying evidence of groundwater infiltration or rainfall-derived infiltration and inflow that may need to be sealed to prevent sanitary sewer overflows
  • Locating structural defects within the pipe that may lead to future pipe failures
Mounted on a wheeled “rover” chassis (shown in Photo 1), closed circuit television (CCTV) cameras provide eyes that assist with maintenance and repairs of the underground sewer system. The camera identifies cracked and broken pipe sections (Photo 2) and locations of debris, grease, or roots (Photo 3) that may block the sewer. CCTV inspection can also identify locations of unwanted groundwater infiltration (Photo 4) that reduce available capacity. Occasionally wildlife, such as a mouse (Photo 5) or a snake (photo 6), enter the system through larger defects. With CCTV inspection, defects can be identified and repaired, restoring the pipe to its proper function (Photo 6)

Detecting problems via CCTV inspection is only half the job; the next step is to fix them. If an obstruction is identified, MWS can send remotely-operated cleaning equipment into the sewer to remove the potential blockage and restore the capacity of the sewer pipe.

If significant structural defects or leaks are observed, MWS has a high-tech solution for that part, too. As long as a pipe isn’t severely damaged, MWS can use a technology called cured-in-place pipe (CIPP) lining to rehabilitate the pipe through the installation of a seamless, tight-fitting, corrosion-resistant liner within the original host pipe.

This new lining improves pipe hydraulics, restores the pipe to a structurally sound condition, and addresses leaks into and out of the sewer.