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The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

More Contact Info

Middle Hillsdale Inflow and Infiltration Pilot Project

Updated March 21, 2019

Environmental Services is nearing completion of 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.


Sewer improvement work occurred on streets identified with bold red lines on the map below.

This project included sewer improvements in the public right-of-way in streets, at curbs, and in planting strips as well as on private properties. Work on private properties was coordinated directly with participating property owners.

Project Map


Environmental Services and its contractor, Titan Utilities, have completed the major sewer improvements for this project. Crews are currently finishing work on lesser tasks to close out the project. They expect to be completed with all work items by the end of April 2019.


This project included the following sewer improvements:

  • Repaired or replaced 4,000 feet of public sewer pipes
  • Repaired or replaced 6,400 feet of private sewer service lateral pipes at a total of 239 private properties

Preventing Sewer Backups and Basement Flooding - What Not to Flush

For many participating properties in this project, the contractor installed 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.

For More Information

If you 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