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Label:
Sewer and stormwater
Label:
Active
Environmental Services is constructing a project to replace a section of large concrete sewer pipe in SW Portland. The Carolina Trunk pipe runs near SW Slavin Road under Interstate 5 to Macadam Ave. It was built almost 90 years ago and needs to be replaced to prevent sewer and stormwater overflows.
Major construction activities began in July 2025. Construction is expected to continue through fall 2028.
The Carolina Trunk is a large sewer pipe - essentially a 3-4 foot wide tunnel deep underground. This pipe is showing signs of deterioration and needs to be replaced. The repairs will maintain sanitary and storm services and help protect public health and the community by preventing sewage releases to buildings and streets.
Project Location
The project area is located in S and SW Slavin Road, between SW Barbur Blvd and S Macadam Ave.
Text description of Carolina Trunk project map
General Schedule
Major construction activities began in July of 2025. Work will be intermittent with phases of inactivity along the project alignment including along Slavin Road, along both sides of I-5, and from SW Corbett Avenue to S Macadam Avenue.
Overall Project Schedule
2025
- Conduct survey work and other preconstruction activities
- Clear and grub construction areas
- Install retaining walls on SW Slavin Road
- Install site monitoring and documentation of buildings/properties
- Prepare sites for construction
Winter/Spring 2026
- Install single traffic lane on SW Slavin Road
- Construct retaining walls on SW Slavin Road
- Prepare shaft locations for excavation
- Begin excavation
Summer 2026
- Excavate shafts at four sites
- Begin excavation/trenching along SW Slavin Road
- Auger bore (tunnel) between each shaft and install casings for new pipes
- Install new pipes inside casing
- Install sewer bypass system in S Julia Street near S Macadam Avenue
Fall 2026/Winter 2027
- Construct "Drop Structures" in Corbett Island (Shaft 3) and S Julia (Shaft 4)
- Continue to install and connect pipes inside casings
Spring/Summer 2027
- Complete final pipe connections
- Backfill shafts and restore construction zones
- Install maintenance access holes
- Complete preliminary paving and restoration
Spring/Summer 2028
- Switch flow over to new pipes
- Test and monitor to ensure work is complete and functional
- Abandon old sewer trunk in place
- Complete final paving and restoration
What's Happening Now
Environmental Services crews are working throughout the project area Monday through Friday, 7 a.m. to 6 p.m. Crews may also work on Saturdays between 7 a.m. to 6 p.m. if needed. I-5, Slavin Road, and SW Corbett Avenue will remain open during this work. Expect some delays, and please watch for signs and follow flagger directions to stay safe.
Slavin Road Noise and Vibration Concerns
The project team has heard from neighbors on Slavin road about issues with noise and vibration. We take these issues seriously and are actively working to reduce disruption to nearby residents. Currently, the team is working with an acoustic engineering contractor to identify a way to help reduce noise and vibration concerns.
While we work to identify a long-term resolution, the project team has taken the following measures:
- Moved start times back one hour so that noisier activities like rock breaking and shoring installwill begin no earlier than 8:00 a.m.
- Continue to monitor vibration levels to ensure they remain below thresholds recommended by vibration experts.
We expect to have more information about what further mitigation measures are feasible soon. Environmental Services staff will provide updates as soon as we know more.
Thank you for your patience during this critical project.
Look-Ahead Schedule
Construction is underway simultaneously in the four work areas. Crews are completing different parts of the underground pipe installation at each location as they work toward connecting the entire pipeline.
The following provides a preview of the work expected in the coming weeks. Work schedules may change in some locations based on securing appropriate permits as well as crew and material availability.
Section 1 - SW Slavin Road
Week of September 28 – Week of October 12
- Continue excavation and installation of the new stormwater pipe along SW Slavin Road.
- Excavation is occurring in sections moving from east to west. Each section will take approximately 3-5 weeks to complete excavation.
- The north lane of SW Slavin Road will remain closed through the work zone until approximately fall 2027.
Section 2 – West Side of I-5
Week of September 28 – Week of October 12
- Begin tunneling operations to install sewer pipe between this I-5 work area and SW Slavin Road.
Section 3 – SW Corbett Avenue ("Corbett Island")
Week of September 28 – Week of October 12
- Beginning October 5, crews will start to build underground concrete structures and install steel reinforcement.
- Nearby residents and travelers on SW Corbett Avenue may see increased construction activity, equipment, and material deliveries.
Section 4 – S Macadam Ave/S Julia Street
Week of September 28 – Week of October 12
- Continue installation of large sewer and stormwater pipes.
- Beginning the week of October 5, crews will begin deeper excavation and underground pipe installation activities.
- The southbound lane closure on S Macadam Avenue is expected to remain in place through approximately October 2.
North Lane of SW Slavin Road Closed Through 2026
Extensive work to excavate and install new sewer and stormwater infrastructure in SW Slavin Road is underway.
To make sure that our crews, residents, and the travelling public stay safe, the north lane of SW Slavin Road has been closed.
Different sections of the north lane of Slavin Road will be closed for approximately 18 months starting in November 2025.
Crews have installed a temporary traffic signal at either end of the work zone that will signal cars through - one direction at a time. Crews will maintain access to properties in the work zone, including driveways and sidewalks. However, there may be some delays.
Please be patient and use caution when using your vehicle in the area. Slow down and obey all signals and signs during this important work.
No Parking on SW 1st near SW Slavin Road
Please do not park on SW 1st Avenue near the intersection with SW Slavin Road. This location is a no-parking zone and needs to remain clear of parked cars to allow traffic to safely access Slavin Road. Crews have installed "No Parking" signs.
If you park in this area, you may be ticketed or towed.
Additional Traffic Impacts
Brief delays along Corbett Avenue and connecting streets will occur during some construction activities. On rare occasions, there may be a need to close the Corbett off ramp. These closures will be limited, and detours will be communicated well in advance.
We do not anticipate traffic impacts on Macadam Avenue, except during a brief period at night near the end of the project.
What to Expect During Construction
Construction creates noise, vibration, and dust and can disrupt normal neighborhood activity. We want you to be safe around the work site. Please keep children, pets, bikes, cars, and trucks away from the tools, machines, supplies, and construction workers. A city inspector will be on-site during work hours and may be able to assist you with construction concerns. Inspectors typically wear a hard hat and safety vest with “City of Portland” on the back.
To learn more about what to expect during construction, please review the brief guide on what community can expect during ongoing projects conducted by Environmental Services.
Noise Impacts
Environmental Services has been granted a permit by the City of Portland Noise Office for this project.
Construction activities generate noise. All work is expected to be at or below City requirements for decibel levels when measured from 50 feet away from the work. Work will include pavement drilling, saw cutting, asphalt grinding, and rock hammering. Crews will be using typical construction equipment, such as trucks, excavators, generators, etc. Some work may occur closer than 50 feet from a residence or structure.
Crews will work to limit noise whenever possible. When appropriate, crews will use sound baffles, white noise backup generators, and other noise reduction measures.
- To report a complaint about construction noise at night during this work, please contact the Environmental Services night work hotline at 503-823-1338
- For general questions about noise and noise permits, please contact the City of Portland Noise Office at 503-823-7350
How We Plan to Build the Sewer Trunk
Crews will begin major construction work in July of 2025, by preparing for open cut construction along Slavin Road. At the same time, crews will begin excavating four different pits.
Once the pits are completed, crews will tunnel between each pit and insert new pipes into the tunnels. Finally, crews will connect the new pipes together, restore Slavin Road and fill in the pits, before final clean up and demobilization.
Work will take approximately three years to complete and will occur in phases with periods of inactivity.
Designers have divided the project into four “sections.” Each section has unique characteristics and will require different construction methods. Please see below for a description of the preliminary design for each reach.
Section One: SW Slavin Road
Section One will require substantial work in SW Slavin Road. Crews will build temporary retaining walls at several locations along the north and south sides of Slavin Road to allow for equipment access.
Crews will need to close the north lane of SW Slavin Road and install new sewer and stormwater pipes using the open trench excavation method. All properties will still be accessible during the work.
Once the retaining walls are in place, crews will excavate a pit at the east end of SW Slavin Road. Crews will enter the pit and connect the new pipes in Slavin road to the new pipes coming up the hill from Interstate 5. Once the connections are made and the work is tested and approved, the construction area will be restored.
Section Two: SW Slavin Road to Interstate-5
For Section Two, crews will dig a pit at the bottom of the hill next to Interstate 5 (I-5). Crews will then tunnel underground between the I-5 pit and the Slavin Road pit and install a new pipe. The majority of this work will occur inside an existing City easement.
Section Three: I-5 to S Corbett Avenue
For Section Three, crews will dig a pit inside the traffic island located on Corbett Avenue, between I-5 and the freeway off ramp. Crews will then tunnel underground underneath I-5, between the pit in S Corbett Avenue and the pit on the other side of I-5.
Section Four: S Corbett Avenue to S Macadam Avenue
For Section Four, crews will dig a pit in the Julia Street Right-Of-Way, near S Macadam Avenue. This pit will be located in an existing parking lot that is partially owned by the City of Portland. Crews will then tunnel underground between the Macadam pit and the pit located up the hill next to S Corbett Avenue.
Once all the tunnels are complete and the new pipes are installed, crews will connect the newly constructed system to the existing system underneath S Macadam Avenue.
Project Background
Sewer trunks are an important part of the City’s sanitary sewer system. Smaller neighborhood sewer lines connect to these trunk lines, which then carry flow of sanitary sewage to treatment facilities. The Carolina Trunk travels under I-5, which makes this project a high priority.
This area of Portland presents its own challenges that the project team must consider. Much of the project area is located on old landfill that is covering an old stream bed. The steep terrain in this part of Portland also presents challenges that the engineers must consider when designing the new sewer pipe alignment.
The current trunk line runs underneath private properties, making it nearly impossible to repair without temporarily displacing residents. Given these challenges, the design team has proposed a new alignment (see map above) that accounts for these challenges. This new alignment will move the trunk and other infrastructure under existing right of way and permanent easements and provide access points to make it easier to maintain in the future.
We Want To Hear From You
We would like to hear from you about special events, school activities, and community services in your neighborhood you think may be impacted by this project. Also, we want to know if you have any concerns related to business operations, disability or mobility issues, medical or business deliveries, and proposed night work. Your input will help us minimize the impact to your neighborhood during construction.
Sign Up For Project Updates
Environmental Services will inform residents and businesses about project activities and respond to questions and concerns in a timely manner. The following resources will help you stay informed and report concerns:
- Project Updates: To receive email or text message updates for this project, sign up now at Sign Up for BES Project Updates. Updates provided through our free GovDelivery subscription service are the best way to stay informed about what’s happening and what to expect. You can also sign up for bulletins on other projects and topics
- Questions: Contact Aaron Abrams at Aaron.Abrams@portlandoregon.gov or call 503-823-2827.
- Sewer Emergency: Call 503-823-1700 immediately. The City Maintenance hotline is staffed all hours, all days (24/7).