Smoke testing involves forcing smoke through the sewer lines to see which cracks or breaks it rises through. If, for example, it rises through the top of a factory, then the Public Works Department knows that this factory's roof drains are directly tied to the sewer line. It could also mean that other pollutants requiring pretreatment are sent directly to the city sewer. The sewer jet unit is used to respond to sewer backups. This also applies to emergency response for the repair of water main breaks.
Main breaks can be severe, causing the loss of large volumes of water from the system.
They can result in street pavement damage from the upward force of the water leaving a pressurized main. This division is also responsible for the location of water mains and sewer lines for various agencies, such as utility companies, contractors and engineers. Line locations are necessary to prevent accidental cutting of utility services during construction or maintenance work. The central garage stores and repairs heavy equipment for all divisions of Public Works and other City offices. Each department pays a fee to cover their portion of mechanics wages and the operating expenses of the garage.