One of Environmental Services’ large sewer tunnels is buried deep under Grand Avenue. Vertical pipes called risers, travel up from the sewer to the street. Risers allow workers to access the tunnel for maintenance. The soil between the tunnel and Grand Avenue is moving and settling. Environmental Services’ tunnel and risers do not move. They stick up into the roadway while the earth settles around them. This makes for a bumpy ride for people driving on Grand Avenue.
The Grand Avenue Riser Stabilization Project will stabilize the soil and roadways around the tunnel’s risers. Going forward, the city will have to do less maintenance work to level out low points on Grand Avenue. This long-term fix means fewer traffic disruptions for nearby businesses and the traveling public.
Project Area
The project area is along Grand Avenue between NE Davis and SE Market streets, at riser locations in six intersections. The project area falls within the boundaries of three neighborhoods—Kerns, Buckman, and Hosford-Abernethy.
What's Happening Now: Emergency Repairs Start Monday, December 15th at Stark and Grand
Crews will be onsite at the Stark and Grand Avenue intersection on Monday, December 15, to perform emergency repairs. At this time, work is expected to last through Thursday, December 18.
No work is currently scheduled at other intersections until early 2026, when permanent paving is anticipated to be installed.
We will send an update later this year with an update on our schedule for paving in 2026.
Construction Impacts
Work Hours: Overnight work hours will be from 7 p.m. to 6 a.m. Monday through Friday.
Duration: Work will occur in phases—grouting, temporary pavement, and permanent repaving.
Equipment Storage: Some equipment and materials may be stored overnight on your street, nearby streets, or other public right-of-way areas.
Periods of Inactivity: Work will occur in phases, and there may be periods of inactivity between phases. A variety of factors, including conditions underground, weather, subcontractor schedules, and availability of materials may affect the schedule.
Maintained Service: Water and other utilities will remain in service during construction.
For more information about the approved night work and the anticipated noise levels, visit the project webpage.
Construction Methods
Crews drilled vertical holes in the work area and pumped grout into the holes. Grout filled voids, compacted the ground, and improved the strength of the soil under the street pavement. Crews have put temporary pavement over the holes. Crews will return in 2026 to install permanent paving.
Approved Night Work
The Portland Noise Office and the Noise Board granted Environmental Services a permit to allow construction to occur mostly at night. Grand Avenue is a major city traffic street, a priority freight route, and a major emergency response route. During construction, crews will have to close three lanes of traffic. A daytime closure would cause gridlock and impact business delivery schedules. Doing work at night will reduce public impacts and allow crews to complete the work as quickly as possible.
Night work allows us to keep Grand Avenue open during peak hours and keep freight delivery schedules on time. It also allows the northbound Portland Streetcar to run during the day and be shut down at night.
Equipment Noise
Equipment that will generate noise during the grouting process includes a:
- Pavement driller
- Generator
- Concrete pump, and
- Flatbed truck and loader.
The highest noise levels anticipated with this equipment will be 70 to 79 decibels, when measured from about 50 feet away. The duration of the highest levels of noise will be short and intermittent. The duration of the lower levels of noise will be more constant for 6 to 8 hours each night.
During pavement restoration a pavement grinder will generate noise. The highest noise level anticipated with this equipment will be 80 to 83 decibels, when measured at about 50 feet. Pavement grinding should take one night at each location.
These noise levels are considered moderate and are not harmful to human hearing:
- A noise level of 70 decibels is similar to the sound of a regular washing machine, a dishwasher, an indoor office environment, or the inside of a car driving at 60 mph.
- A noise level of 80 decibels is similar to the sound of an alarm clock, a garbage disposal, and regular urban traffic. It is less than the sound of a passing diesel truck, a leaf blower, a lawn mower, or a food processor, which are between 85 and 95 decibels.
- These levels are much less than the sound of a chainsaw, a jackhammer, riding a motorcycle, or an emergency vehicle siren, which are between 100 and 120 decibels.
Environmental Services requires measures to reduce the effect of noise. These include noise deflector panels, generator muffling panels, restrictions against vehicle idling, and restrictions against vehicle backing up alarms.
Project Background
Construction materials used on Grand Avenue over the past century do not meet modern standards. The mixture of materials layered on top of one another is unstable. Thousands of vehicles travel on this busy road every day, and it is slowly shifting and changing shape. The road is especially bumpy near sewer utility holes, where the road is settling but the pipes are not. Environmental Services decided that instead of repaving the street, it would develop a long-term solution. The solution involves stabilizing the soil around the maintenance holes. Construction crews will stabilize the soil by injecting it with a material like concrete called grout. They will drill holes into the ground around the risers and fill the holes with grout to make the soil more stable.
We Want to Hear from You
Here are ways you can stay informed and let us know your questions and concerns:
- Project Webpage: Visit this project webpage for updates using the shortcut www.portland.gov/bes/grandave.
- Questions: The communications firm PRR is assisting city outreach staff. Contact Love Lee via email at llee@prrbiz.com or by phone at 206-462-6395. Be sure to include your name, business name, property address, and project name (Grand Ave Riser Stabilization) in your messages so we can provide you with details about what to expect near your property.
- Email Updates: Sign up for email updates at portland.gov/bes/signup.
- Nighttime Construction Noise Complaint: Call the noise hotline at 503-823-1338, stating that Grand Avenue Riser Project is your area of concern. The noise hotline is monitored by site inspectors.
- Sewer Emergency: In the event of a sewer backup or basement flooding, call the City Maintenance hotline immediately at 503-823-1700. It is staffed all hours and all days, 24/7.
Sign Up for Updates
Sign up for regular email or text message updates for the Grand Avenue Riser Stabilization Project through our free GovDelivery subscription service. These updates 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.
This project will help protect the health of the Willamette River Watershed.