The City of Portland utilizes Trenchless Technology to rehabilitate sewers when possible. Trenchless technologies allow for pipes with structural or root issues to be repaired without having to dig and replace, limiting the impact on roadways, residents, businesses, and everyday life.
The most common method used is Cured-In-Place-Pipe lining. The basic idea is to pull a resin filled sleeve, or liner, into the existing sewer. This sleeve is then inflated so it is pressurized and pushing against the pipe. The resin in the liner is then cured using hot water, steam, or ultra-violet (UV) light. The cured liner essentially replaces the host pipe and covers up any cracks, holes, old laterals, and other areas that can allow roots to enter into the sewer. Roots can allow debris to cause a blockage which can lead to a sewer backup so this technology helps prevent root intrusion through pipe joints.
During this process, sewer laterals are blocked during the cure so we ask residents to limit their water usage during that time to prevent any backup issues. Once cured, the laterals are cut out and service is restored. Below is a brief video showing the sewer rehabilitation process using UV curing and a industry white paper explaining different types of rehabilitation.
FREQUENTLY ASKED QUESTIONS:
Will you be digging up my street?
In most cases, the answer is no. When possible, the City uses trenchless technologies to limit the amount of disruptions. If necessary, a point repair is completed on a small section of sewer prior to rehabilitation which does require some digging.
Why shouldn't I shower or do laundry when the sewer is being rehabilitated?
During the lining process, laterals (the pipe from your house to the sewer) can be blocked for several hours when the liner is inflated and being cured. During that time, heavy water usage could result in a back up in your home. Flushing your toilets and washing your hands shouldn't be an issue but please limit bathing, laundry, or other heavy water usage.
What's that smell?
You may notice a chemical or sewage smell during or after the rehabilitation project. Sometimes, during the cleaning process prior to lining, plumbing traps in your house can lose their water and allow sewer smells through. To fix this, make sure to add water back into a floor drains or traps you might know of. A chemical smell is from the resin filled liner. While not pleasant, the smells are not harmful.
Will my lateral be lined?
At this point, the City is only rehabilitating the main sewer. Laterals are the responsibility of the property owner. All active laterals will be restored during the rehabilitation process to ensure reliable sanitary sewer service.
What types or curing methods are there?
Resin filled liners can be cured with hot water, steam, or UV light. UV light is the cleanest as it requires no additional water and the liner comes with the resin, limiting unpleasant odors. It can be slower with the light train moving around 6' per minute but it allows for crews to inspect and stop the cure as needed to ensure a good result.
For more information or assistance, please contact Benjamin Pearson, PE, Compliance Section Coordinator, Water Resources Division at email@example.com or 207-874-8843.