Smoke testing yields clues for system repair

Originally Published 8/26/2015

CLEAN 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.

“Smoke testing” is a process of injecting artificially created, non-toxic smoke into the sanitary sewer system at manholes and observing the locations where smoke exits. Smoke exiting from the ground, from storm drains, around manholes, or other locations indicates that a defect may be present that would allow stormwater or groundwater to enter the sanitary sewer system.

When smoke testing reveals defects in the portion of the system owned by MWS, Clean Water Nashville may take steps to schedule and conduct repairs in order to improve the performance of the sewer system. The program may also notify customers of repairs or corrections that are the responsibility of the homeowner.

The goal is to keep stormwater and groundwater out of the sanitary sewer system. When stormwater or groundwater enters the sanitary sewer system through damaged pipes or improper connection sources, it takes up valuable capacity in our sanitary sewer lines, especially during heavy rain events. Reducing the amount of rain water in the sanitary sewer system saves money for Metro Water Services and its ratepayers and helps prevent capacity related overflows.

Clean Water Nashville, through its contractors, provides advance notice to residential and business customers located in areas where smoke testing of sewer lines will occur. Communication includes door hangers that provide a description of smoke testing and contact information for Metro Water Services (and for the contractor conducting the work). Customers who have questions about smoke testing being conducted in their neighborhood can contact MWS at 615-862-4600 for more information.