The Grand Avenue Riser Stabilization Project aims to stabilize the underlying soils and street base to address roadway settlement caused by construction materials from a century ago. These historical mixed-fill materials do not meet modern engineering standards for underground construction, leading to unstable soils around the deep Southeast Interceptor sewer tunnel. To mitigate these issues, the project team designed a long-term solution to stabilize soils and prevent roadway settlement by reinforcing the soil around maintenance hole risers along Grand Avenue. Crews will inject the soil surrounding the maintenance holes with a material that makes the soil more stable.
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.
General Schedule
Construction is currently scheduled for April 2025 to April 2026, which includes approximately 28 weeks of night work to complete soil stabilization work and pavement restoration. Overnight work hours will be 6 p.m. to 7 a.m. Monday through Friday.
Work is expected to take four to five weeks at each location and will occur in phases--injecting grout into the ground to stabilize the soil, restoring the asphalt disturbed by the grouting installation with temporary pavement, and repaving with permanent paving.
Construction Method
Crews will inject grout into the soil to fill voids, compact the ground, reduce water seepage, and improve the strength of the soil under the street pavement. 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.
What's Happening Now
Environmental Services has completed the contractor bid and selection process and is finalizing a contract with the company who will build the project. When the contract is finalized, crews will prepare for construction. Construction is anticipated to begin this April.
Approved Night Work
The Portland Noise Office and the Noise Board granted Environmental Services a noise variance to allow construction to occur mostly at night to reduce public impacts and complete the work as quickly as possible. Grand Avenue is a major city traffic street, a priority freight route, and a major emergency response route. A daytime closure of three lanes on Grand Avenue would cause gridlock during peak commute hours and significantly impact business delivery schedules.
Night work will avoid a daytime closure of Grand Avenue during peak hours, a daytime service closure of the Portland Streetcar, and disruptions to daytime freight delivery schedules on Grand Avenue. An agreement with Portland Streetcar will enable a service shut down during evening hours; a daytime service shut down is not permitted.
Equipment Noise
Equipment that will generate noise during grouting installation will include a pavement driller, a generator, a concrete pump, and a flatbed truck and loader. The highest noise levels anticipated with this equipment will be 70 to 79 decibels, when measured at about 50 feet. Duration of the highest levels of noise will be short and intermittent. Duration of the lower levels of noise will be more constant for 6 to 8 hours each night.
Equipment that will generate noise during pavement restoration will include a pavement grinder. The highest noise level anticipated with this equipment will be 80 to 83 decibels, when measured at about 50 feet. Pavement grinding is anticipated to 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 will require noise mitigation measures that include noise deflector panels, generator muffling panels, restrictions against vehicle idling, and restrictions against vehicle backing up alarms.
What to Expect
You can expect the following activities and impacts:
- Work Hours: Overnight work hours will be from 6 p.m. to 7 a.m. Monday through Friday.
- Duration: Work is expected to take four to five weeks at each location and will occur in phases—grouting, temporary pavement, and permanent repaving.
- Local Access: Local access will be provided to all properties and driveways. Expect delays.
- Traffic Delays: Expect traffic delays in and near the work area due to overnight lane closures to enable construction activities. Please observe traffic control devices and signs and follow the directions of flaggers if present.
- Parking Restrictions: On-street parking will be restricted in and near the work zones to create a safe work environment and to stage equipment and materials.
- Equipment Storage: Some equipment and materials may be stored overnight on your street, nearby streets, or other public right-of-way areas.
- Noise, Vibration, and Dust: Construction creates noise, vibration, and dust.
- 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.
Learn more about what to expect during pre-construction and construction.
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 Katy Asher via email at kasher@prrbiz.com or by phone at 206-462-6390. Be sure to include your name, business name, property address, and project name (Grand Ave) 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.