Annual Sanitary Sewer Line Inspections

Each year, the Wastewater staff uses sound wave equipment (SL-RAT by Infosense) to identify flow restrictions and/or blockages within the sanitary sewer gravity lines. There are two devices used to perform these inspections. The first device is placed in a sanitary sewer manhole, which sends out acoustics (or sound waves) to a second receiving unit inside the adjacent downstream/upstream manhole. When the sending unit begins, there is an unusual noise that emits from the manholes for a short period of time during the process. Click here to listen to the acoustic sound waves. The receiving unit then determines the flow conditions of the sewer main line by the sound waves received and assigns a 1-10 rating. This rating will make the determination of whether the line needs to be cleaned or not. In most cases, only a very small percentage of the lines inspected need to be cleaned. 

By using this equipment, the city saves thousands of gallons of water used to clean the lines, saves numerous staff hours to set up and clean sewer lines that do not need to be cleaned, reduces the chance of causing water damage within homes or businesses during the traditional high pressure line cleaning process, and significantly reduces traffic impacts. 

If you have any questions, please call the Wastewater Treatment Plant at (253) 851-8999.