sewer smoke tetra tech

Sewer smoke testing has officially started as of July 10 in Duncan.

Pink slips are circulating the city indicating sewer smoke testing has officially started as of July 10 in Duncan.

City of Duncan contracted with Tetra Tech Inc., Consulting Engineers to complete an evaluation of the sanitary sewer system. This is the second year of the four year study approved by Duncan City Council, under the guidance of City Manager Kimberly Meek, which will identify Duncan’s Inflow and Infiltration (I&I) or other sanitary sewer collection system conditions “which contribute to heavy wet weather flows and/or collection system overflows.”

The system has been broken into study areas, which will be inspected each year during the four year term.

Meek previously said work includes “installation of flow level tracking equipment, GPS locates of manholes, GIS mapping, a sanitary sewer evaluation survey and assistance with the development of private property I&I abatement policies and procedures.”

According to Meek, heavy rainfall during 2015 and 2016 made deficiencies “egregiously obvious” in the Wastewater Collection System.

“The Wastewater Treatment Plant is designed to treat a peak flow of 6.25 million gallons per day of wastewater,” Meek said. “During the recent years’ intense rain events, incoming flow at the WWTP have been observed in excess of 13 million gallons per day.”

This portion of the project with Tetra Tech Inc. consists of inspection of 185 manholes and smoke testing of approximately 88,000 feet of sewer line.

Crews with the company began circulating in May 2019, accessing manholes in alleys, streets and backyards and lifting the manhole lids to perform inspections. In the next few days, those crews with Tetra Tech for the City of Duncan will be conducting a physical survey of a portion of Duncan sanitary sewer system. On July 10, crews began their work in areas of Fir Street to Highway 7 and from B Street to Hamilton Street.

During the process, workers will access manholes in order to “smoke test” sewer pipe and locate defects in the system. The smoke that is visible from the vent stacks on houses or holes in the ground is non-toxic, harmless and creates no fire hazard.

Smoke notices from City of Duncan and Tetra Tech state smoke should not enter homes unless there is defective plumbing or died up drain traps. If seldom used drains are in the home, residents should pour water in the drain to fill the trap, which should prevent smoke from entering. Drain traps should always be filled with water to prevent sewer gases or odors from entering the building. If the smoke enters through faulty plumbing, the potential exists for sewer gases to enter your home or establishment, and you should consult your licensed plumber to fix that problem.

Some sewer lines and manholes may be located in backyards. Whenever these lines require investigation, members of the inspection crews will need access to the sewer lines and manholes. These crews are Tetra Tech Inc. personnel and will be identified with uniforms and badges. Homeowners do not need to be home and at no time will field crews have to enter your business or residence.

The information from this study will be used to improve sewer services by identifying defects for rehabilitation that will reduce the amount of storm water getting into the sanitary sewer system, causing the sewer system to overload during storms.

“As you observe these crews working throughout your neighborhood, remember they are there helping your community to improve your sanitary sewer service and making your city a better place to live,” states a release from Tetra Tech.

The contract with Tetra Tech includes additional work, such as an acoustic blockage test using a sewer line rapid assessment tool, SL-RAT, manhole dye testing, storm cross-connection tests and creek crossing inspections.

If you need special assistance or would like more information, contact Terri Kuykendall with Tetra Tech Inc. by calling 580-560-4658. For additional information, visit