Based on pipeline maintenance requirements, certain sewer lines are selected each year for replacement. The Public Works Department designs, manages and inspects these projects to ensure the new infrastructure meets the objectives set forth by the City.
The Wastewater Collection program seeks to:
- Replace aging, deteriorated, deficient, or otherwise troublesome sewer infrastructure
- Reduce or eliminate periodic maintenance requirements and emergency repairs
- Reduce infiltration and inflow of storm water
- Ensure uninterrupted sewage flow without health hazard or effluent leakage
Many sewer lines selected for replacement are failing due to age—some are nearly 100 years old or more! Other replacements are due to failures from severe root intrusion, broken joints or other deterioration and deficiencies. Additionally, they are frequently too small in diameter to accommodate appropriate flow capacities and require high levels of maintenance. Replacing these sewer lines ultimately results in lower costs and reduced customer impacts that would otherwise be associated with emergency repairs. It also provides more staff time for preventive maintenance, which prolongs the expected service life of wastewater collection facilities and equipment. New more appropriately-sized sewer lines reduce infiltration and inflow of storm water and provide uninterrupted sewage flow without health hazard or effluent leakage.
A large portion of the City’s sewer pipeline infrastructure is comprised of clay pipe. In the early part of the 20th century, clay pipe was the industry standard due to its inexpensive cost, ease of installation and long life. However, over the years, the existing sewer lines have been failing from age and breakage of the pipe joints. High Density Polyethylene (HDPE) pipe is the material of choice for pipe replacement. It’s stronger, lighter, flexible and is capable of handling larger volumes of sewage than the same size of clay pipe. HDPE has been proven to a 50-year design life.
A new HDPE sewer line is installed, avoiding existing utilities »
In some instances, it’s not practical to install new sewer piping, such as trenching in a busy street, resulting in traffic congestion and inconvenience to the public. One very effective solution to this problem is to install a resin-impregnated liner to existing sewer pipe which seals the inside of the pipe and requires minimal disturbance to the street above. Another method is called “pipe bursting” where the existing clay pipe is broken up with new pipe following behind in its place.
« A new sewer liner is rolled out for a nighttime installation.