Public Infrastructure Inspections

Smoke Testing

Smoke testing consists of introducing non-toxic smoke into sanitary sewer pipe sections under moderate pressure. An inspection crew will travel throughout the neighborhood, lifting manhole lids, setting out testing equipment, and entering yards to observe and record the smoke testing. Before smoke testing occurs in your area, residents and property owners will receive a letter with additional information.

Since the smoke will be placed into the sewer system that is connected to homes, residents are encouraged to pour tap water into their floor drains and sinks. This small amount of water creates a seal that keeps the smoke out of the homes. Residents do not need to be present during smoke testing.

Dry traps, drains without traps, and other plumbing defects will allow the smoke to enter the dwelling connected to the sewer line that is being tested. The smoke is non-toxic, leaves no residue, and creates no fire hazard. If a resident is present and smoke enters the house or building, please report all locations to the work crews and open a window to allow the smoke to dissipate. It may also be desirable to contact a plumber if the smoke enters the house in a manner other than a dry drain trap.

Smoke testing is most effective when performed during the times that the ground is dry, such as August and September. For additional information, call the City at 563.589.4270. 


Cross-Connection to Storm Sewer

Manhole Inspections

Sanitary sewer manholes provide access to the collection system for maintenance and repair. Sanitary sewer manholes within each sewershed will be opened and recorded as concrete or brick. Brick manholes are of the greater I&I concern because they are typically older, and deteriorated mortar can be a significant source of infiltration. Many of the brick manholes in the City are approaching 100 years old.

After the brick manhole locations are recorded, their condition is ranked to determine an improvement or replacement priority. Brick manholes with a poor or very poor rating are typically repaired first while the remaining brick manholes are addressed in subsequent years based on age (i.e. the older manholes will be replaced first) and priority rankings in the other sewersheds.

Sanitary Sewer Televising

Televising allows Engineering and Public Works staff to see inside the sanitary sewer. The condition of the pipe is recorded as a camera moves through the pipe. The pipe condition and its location are then used to establish a pipe priority grade. Establishing priority grades ensures that the City’s resources are being used to maintain and/or rehabilitate the more critical areas within the system first and allows time to develop a schedule to investigate the less critical areas at a later date.