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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Suite 1000, Portland, OR 97204

SW Terwilliger Boulevard Sewer Project

Environmental Services will construct 6,800-feet of eight-inch gravity sewer inTerwilliger Boulevard from SW Powers Court to Highway 43. The new sewer will connect to the 30-inch Tryon Interceptor sewer, which carries sewage to the Tryon Creek Wastewater Treatment Plant in Lake Oswego. This improvement to Portland’s wastewater collection system will help protect water quality, public health, and the environment.


Environmental Services, traffic consultants, the Portland Bureau of Transportation, Multnomah County, the City of Lake Oswego, Sellwood Bridge contractors, and Clackamas County have been working together to coordinate traffic and schedules of construction projects in the area. Impacts on residents and property owners, public health, and the schedules of other projects in the area are a major consideration and influence the development of the traffic management plan during the closure ofTerwilliger Boulevard.


The design is nearly complete, and the project will be advertised for contractors to bid in March.  Construction could start as early as July and will take about one year to complete.


  • SW Terwilliger Boulevardwill be closed to all traffic from the Iron Mountain Trailhead to Highway 43 for the duration of the project.
  • Work on Highway 43 will close one lane in both directions for up to five weeks while installing a manhole and connecting to the existing sanitary sewer line under Highway 43. The contractor will keep one southbound lane and one northbound lane on Highway 43 open during construction.
  • The Terwilliger Trail will remain open for pedestrians and cyclists. There will be advance notification of any closures needed to construct the sewer branches to properties along the trail.
  • There will be traffic delays during construction hours.
  • Parking will be prohibited in the work zone.
  • There may be periods of inactivity between construction phases.
  • A city construction inspector will be on-site during work hours. If you have an immediate need during construction, the on-site inspector may be able to assist you. 


The City of Portland and Clackamas County have granted Environmental Services a noise variance for some work outside of normal construction hours. Most construction will take place during the day between 7:00 a.m. and 6:00 p.m. The noise variance will allow the city’s contractor to extend construction hours to 7:00 p.m. for up to 60 days, and to 10:00 p.m. for ten days to deal with unforeseen circumstances. In addition, construction crews will work overnight from 9:00 p.m. to 7:00 a.m. during the final ten days of the project to complete surface grinding, paving and traffic line painting.


Go to To receive email updates for this project, send an email to Debbie Caselton at with “Terwilliger” in the subject line.

Thank you for your cooperation during this project. Please let us know if you have concerns such as business operations, disability issues or medical or business deliveries. As always, we strive to provide a quick response to your concerns, minimal disruption of your residence or business, and open and honest communication with you throughout the project. 

Download Summer 2013 newsletter here.

SW Terwilliger Blvd Sewer Project Update: October 18, 2013

sw terwilliger project area map

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