The project also includes relocating a mainline public sewer pipe from private property south of Sam Jackson Road near Duniway Park. Relocating the pipe will improve sewage flows and increase accessibility for future maintenance.
Project Area
The project is located in Duniway Park and along SW Sam Jackson Park Road just west of Duniway Park.
Project Background
Portland’s population rapidly expanded at the turn of the 19th century. In response, the city built hundreds of miles of sewer infrastructure. The area we now known as Duniway Park was originally part of Marquam Gulch. Marquam Creek flowed through this gulch down to the Willamette River. In 1912 city engineers designed and built a large sewer collector trunk that followed Marquam Creek’s natural drainage path. This collector is known as the Sheridan Trunk. Building large trunks in this way was typical for the time. We now have large sewer trunk lines following the natural courses of creeks and streams throughout the West Hills.
In the early 1900s, the deep ravine that carried Marquam Creek was filled with waste—a common practice at the time. The dump site primarily contained burnable organic materials and street-sweeping debris. In 1918, Duniway Park was built on top of this fill site with the sewer trunk line lying in the old creek bed at the bottom.
Most sewer pipes have a lifespan of about 100 years. Large portions of our system are now reaching the end of their service life. Portland faces an urgent need to modernize its aging infrastructure. The Sheridan Trunk Project is part of Environmental Services’ citywide effort to repair or replace the highest-priority pipes, ensuring a safe, efficient, and reliable sewer system that protects public health and the environment.
Construction will create noise, vibration, dust, and other disruptions to normal neighborhood activity. Planned excavations in Duniway Park may also produce occasional odors. We understand that construction may temporarily impact your enjoyment of the park and its surroundings. However, these essential upgrades will strengthen the area’s infrastructure for decades to come and help protect the health of our community and our rivers.
Project Timeline
Our anticipated sequence of events over the next several months and into construction:
Now – April 2027
- Preconstruction Activities: Crews will be in the area to survey, collect additional soil samples, confirm the location of utilities, tree trimming, removal and protection and site preparation. Some investigative activities may require restricting parking and closing travel lanes. Go to Pre-Construction Activities | Portland.gov to learn more.
April 2027 – September 2029
- Bikeway and pedestrian lane improvements to the path surrounding Duniway Park on SW Terwilliger: This will be developed before construction begins to allow for construction vehicles to safely enter and exit the park and for pedestrian and cyclist safety and access during construction. Some construction activities may require closing travel lanes for a short period of time.
- Sewer Construction in Duniway Park and on SW Sam Jackson Road
- Duniway Park and Lilac Garden Restoration
Bicycle and Pedestrian Safety Improvements Near Duniway Park
Prior to sewer construction, bike lanes and pedestrian paths that surround the park on SW Terwilliger Boulevard will be updated to create a safe environment for people walking and biking by mitigating the risks associated with heavy construction vehicles and equipment moving in and out of Duniway Park. These improvements are permanent and will remain in place once construction is completed.
Improvements include:
- Restriping SW Terwilliger Boulevard to widen the westbound bike lane along SW Terwilliger Boulevard, adding a 2-foot buffer
- Extending that westbound bike lane to the intersection with SW Sam Jackson Park Road
- Constructing a 7-foot wide sidewalk-level bike lane for bikes traveling eastbound on SW Terwilliger Blvd
- Constructing a 7-foot wide sidewalk along Duniway Park adjacent to the sidewalk-level bike lane
- Installing a bright yellow rumble strip to separate bikes from pedestrians (see photo)
- Installing an Americans with Disabilities Act (ADA) ramp, bicycle ramps, bike crossing markings and paved bicycle waiting area on the north side of the SW Sam Jackson Park Road and SW Terwilliger Boulevard intersection
- Removing the traffic island at the intersection of SW Sam Jackson Park Road and Terwilliger Boulevard and shortening the crosswalk on the south leg of the SW Sam Jackson Park Rd and SW Terwilliger Blvd intersection
- Adding high visibility crosswalk striping at the intersection of SW Sam Jackson Park Rd and SW Terwilliger Blvd intersection
- Extending the southbound bike lane striping from SW Sam Jackson Park Road to connect to the existing designated bike lane on southbound Terwilliger Boulevard to provide a unbroken designated bike lane
Duniway Park Impacts and Restoration
Visiting Duniway Park and Surrounding Area During Construction
During construction, materials and large machinery will be delivered and stored in Duniway Park and nearby areas to facilitate sewer construction using the Jack and Bore method. The Jack and Bore method will involve digging large pits in the park. Portions of the park near construction zones may be closed for extended periods, ranging from several days, weeks, months or throughout the entire project. Closures are necessary for the safety of the crew and community. Closed areas will be clearly marked. Please stay clear of work zones and observe direction of signs and flaggers when present.
The movement of trucks and equipment will generate noise, vibration, and dust, and the excavation work may occasionally produce odors. Some tree trimming and removal will be required as part of the construction process. These trees will be replaced at the end of construction or as directed by Urban Forestry or Portland Parks & Recreation.
Impacts to the Historic Lilac Garden
The sewer construction project will involve excavating parts of upper Duniway Park and the historic Lilac Garden, necessitating the permanent removal and relocation of some lilacs. Lilacs that remain in place during the project will be carefully protected. Restoration plans are currently being developed to restore the garden with an updated planting plan to improve drainage, access, and plant health.
Night Work Expected on Sam Jackson Park Road
To minimize impacts on residents, businesses, and the traveling public, Environmental Services plans to apply for a noise variance to perform nighttime construction work. This work will involve building sewer service connections from private properties along SW Sam Jackson Park Road to the new Sheridan Sewer Trunk, once it has been constructed. Scheduled as one of the final phases of the project, this work is anticipated to occur in 2027.
Before applying for the noise variance, Environmental Services will provide nearby property owners and tenants with detailed information about the expected number of nights of work, nighttime construction hours, equipment to be used, and measures to reduce noise. Property owners and tenants will also have an opportunity to provide comments during this process.
Construction Methods
- Open Trench: The contractor excavates a trench, installs a new pipe, fills in the trench, and restores the disturbed area. This method is necessary at certain areas within the project that Jack and Bore is not a suitable method.
- Jack and Bore: Is a trenchless method of sewer construction. It is suitable for installing short pipe runs (100 to 500 feet long) in stable soil without large boulders. This method helps to reduce additional disruption to the community.
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 might be impacted by this project. Also, we want to know if you have any question or concerns related to how this project might impact your use of Duniway Park. Your input will help us minimize the impact to your neighborhood during construction.
Sign Up for Updates
Sign up for periodic email or text message updates 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 Williamette River Watershed.