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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

MAILING ADDRESS: 1120 SW 5th Ave, Room 1000, Portland, OR 97204

More Contact Info

Middle Hillsdale Inflow and Infiltration Pilot Project

Updated September 5, 2018Button. Click to sign up for email updates

Environmental Services is continuing construction on a project to reduce the inflow and infiltration of stormwater and groundwater into separated sanitary sewer pipes in Southwest Portland (pipes that are designed to carry only sewage). When storm drains are directly connected to sewer pipes or when cracks in sewer pipes allow groundwater to flow into them, this inflow and infiltration can overload the public sewer system and cause overflows into ditches and nearby waterways. By repairing sewer service laterals that connect houses and properties to the main line public sewer, this project will help keep stormwater and groundwater out of the sanitary sewer system and reduce the risk of overflows.

Preventing Sewer Backups and Basement Flooding - What Not to Flush

For many participating properties in this project, the contractor is installing a backwater valve to help prevent sewer backups and basement flooding. The flap valve makes sure sewage and stormwater flow in one direction only, away from a home. In the event that sewage and stormwater rise and flow back into a home, the backwater valve blocks the sewage and saves the home from experiencing basement flooding problems.

The backwater valve can become clogged, however, if you flush so-called "flushable" products down the toilet. Products advertised as flushable -- like some wipes, diapers, and feminine hygiene products -- don't break down in water and frequently block sewer pipes. Protect your home from potential sewage floods by flushing only human waste (urine and feces) and toilet paper down the toilet.

For details about what not to flush, click here.


Work will occur on streets identified with bold red lines on the map below:

  • Some work will occur in the public right-of-way in streets, at curbs, and in planting strips.
  • Some work will occur on private properties. Work on private properties is being coordinated directly with participating property owners.

Project Map


Crews are working throughout the project area. You can expect the following with this project:

  • Crews may be working at multiple locations at one time in different phases of work.
  • The city's contractor, Titan Utilities, will provide advance notice of construction as they prepare to move to a new area.
  • Titan will contact participating property owners before work occurs on private property.
  • Approved work hours are 7 a.m. to 6 p.m. Monday through Friday, and Saturday if needed.
  • Construction is anticipated to be completed by the end of March 2019. The project has been extended due to coordination with property owners and other factors.

What to Expect During Construction

The contractor, Titan Utilities, is conducting work in phases throughout the project area:

  • Inspecting service laterals that connect private properties to the main line public sewer
  • Developing work plans for each participating property
  • Meeting with property owners to review and approve work plans
  • Obtaining plumbing permits
  • Installing cleanouts for sewer line access for repairs and future maintenance
  • Installing backflow valves to help prevent basement flooding
  • Completing spot repairs where needed
  • Repairing or replacing service laterals using the Cured-in-Place-Pipe Lining method or the Pipe Bursting method
  • Repairing major sags in service laterals using the Open Trench Excavation method
  • Restoring grassy areas and pavement disturbed by construction

For more information on the neighborhood and street impacts you can expect during construction, see the Project Overview.

Construction Methods

The city’s contractor will use trenchless methods where possible to replace most of the laterals on private property, which will reduce the amount of excavation required.

Because of higher than anticipated groundwater levels in the central and southern sections of the project area, the city's contractor had to switch construction methods from Cured-in-Place-Pipe Lining to Pipe Bursting. While pipe bursting is still a trenchless method, it is more disruptive. In addition, some digging is necessary to repair major sags in sewer pipes. Click here for more information about the construction methods used in this project, including Cured-in-Place-Pipe Lining, Pipe Bursting, and Open Trench Excavation.  

As the contractor moves from property to property, they assess conditions and determine the best approach for replacing the sewer service laterals. 

For More Information

Please note that the city is not accepting additional properties into the project. If you are uncertain about the status of your participation in this project, or have questions and concerns you would like to discuss, please call or email:

Cheryl Kuck
Community Outreach
Phone: 503-823-7898

If you have a concern or question about the work near you, please be sure to include your name, property address, and project name (Middle Hillsdale RDII) in your voicemail and email so we can provide you more details about what to expect in front of your property. Also, please write "Middle Hillsdale RDII" in the subject line of your email.

Project Overview

Including the project description, map and schedule

Community Outreach

Check out current and previous communications about the project