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 Area
The project area is located in S and SW Slavin Road, between SW Barbur Blvd and S Macadam Ave.
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.
What's Happening Now
Environmental Services crews are working throughout the project area.
Regular City of Portland construction hours are 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.
Work schedules may change in some locations based on securing appropriate permits as well as crew and material availability. We will keep you informed as the schedule is updated.
North Lane of SW Slavin Road Close on November 3 for Approximately 18 Months
Crews have begun construction on retaining walls on the north side of SW Slavin Road. Once the retaining walls are complete, crews will excavate the north lane of SW Slavin Road in sections and install new pipes. Crews will also dig a pit on the north side of Slavin Road near the intersection with SW Viewpoint Terrace. This work will close the north lane of SW Slavin Road.
To make sure that our crews, residents, and the travelling public stay safe, the north lane of SW Slavin Road will be closed intermittently beginning the week of November 3rd.
Different sections of the north lane of Slavin Road will be closed for approximately 18 months starting in November 2025.
Crews will install 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.
Pit Excavation Work Will Generate Noise
Crews have begun constructing pits throughout the project area.
During pit excavation, crews will install steel piles around the perimeter of the pit. Steel plates will be driven into the ground between the piles, and then soil will be excavated out behind the plates. This creates a support structure to hold back the hillside and keep the pit safe for work.
Pit construction and excavation will generate loud noises during many periods of work.
Look-Ahead Schedule
Crews are working throughout the project area. The following provides a preview of the work expected in the coming weeks.
SECTION 1 – SW SLAVIN ROAD
The following work is expected at this location:
Week of January 5 – Week of January 12
- Crews will continue construction of the retaining walls located on the north side of SW Slavin Road.
Week of January 19
- Crews will begin bringing steel piles to the pit located at the east end of SW Slavin Road.
- Crews will continue construction of the retaining walls located on the north side of SW Slavin Road.
The north lane of SW Slavin Road is currently closed through the work zone and will stay closed for 18-24 months.
SECTION 2 – WEST SIDE OF I-5
The following work is expected at this location:
Week of January 5 – Week of January 19
- Construction on I-5 pit will continue. Crews will install support plates and excavate the pit.
- This work will cause intermittent vibration and loud noises during daytime hours.
SECTION 3 – SW CORBETT AVENUE ("Corbett Island")
The following work is expected at this location:
Week of January 5 – Week of January 19
- Construction on the Corbett pit will continue. Crews will install support plates and excavate the pit.
- This work will cause intermittent vibration and loud noises during daytime hours.
SECTION 4 – S MACADAM AVE/S JULIA STREET
The following work is expected at this location:
Week of January 5 – Week of January 19
- Construction on the Macadam pit will continue. Crews will continue to install steel piles and plates to stabilize the area and excavate behind the plates as they are installed.
- This work will cause intermittent vibration and loud noises during daytime hours.
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.
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 in to 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.
Traffic Impacts
Crews have closed the north lane of SW Slavin Road and installed temporary traffic lights at either end of the work zone. These traffic lights allow vehicles to travel through the work zone using the south lane in one direction at a time. This one-lane configuration will be in place for the duration of work on SW Slavin Road.
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.
When driving near construction work, please slow down, obey all flaggers and signs, and use caution.
Impacts to Private Property
Due to limited space in the work zone, it may be necessary for crews to use private property to store materials and equipment, install temporary retaining walls, and conduct construction activities.
City Staff will continue to work with nearby property owners to acquire easements and other permissions for work that may impact some private properties adjacent to Slavin Road. Over the coming months, staff will continue to engage nearby property owners.
Environmental Services staff are working with property owners located within 100 feet of the construction work to videotape structures and install settlement monitoring. Please look for a letter in your mailbox if you live close to the project area.
Noise Impacts
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.
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).