1120 SW 5th Ave, Suite 613, Portland, OR 97204
The City of Portland’s Bureau of Environmental Services is continuing our work to repair and replace critical sewer and stormwater infrastructure. Environmental Services will continue to provide information and updates on construction schedules and activities during the COVID-19 emergency.
Updated October 22, 2020
Construction continues on the 114-year-old Taggart Outfall—a large, brick sewer tunnel located deep underground. This critical sewer line serves Southeast Portland. Repairs will increase the sewer’s resiliency, extend its service life for up to another 100 years, and help prevent sewage releases.
The Taggart Outfall drains a large area of Southeast Portland and conveys overflows from the combined sewer system to the Willamette River during rain events. It is located deep underground in a difficult location close to TriMet light rail tracks, Union Pacific Railroad tracks, and Highway 26/Powell Boulevard. A structural failure of the Outfall would have profound impacts on this area, potentially flooding numerous businesses and residences and resulting in many millions of dollars of property damage and disruption.
Aboveground construction activities are concentrated at existing manholes along the Taggart Outfall and a sewer access shaft on private property. Most of the repair work occurs belowground from inside the sewer tunnel.
The city's contractor will complete the current phase of repairs this fall season. Crews will return next summer to complete an additional work item in the sewer tunnel.
Activities for the next few weeks will include the following:
One aspect of the project will require additional work during next year's dry-weather season—the installation of a cementitious liner. An unusually high water table this summer combined with delays due to wildfire smoke necessitated postponing this work.
Next summer, using manholes to access the sewer tunnel, crews will install a concrete liner over the surface of 433 feet of bolted tunnel liner plates to create a smooth finish. This work will take about four weeks to complete. Environmental Services will notify residents and businesses when that work is scheduled.
The Portland Noise Office granted Environmental Services a noise variance to work all hours and all days (24/7) in the industrial areas of the project west of TriMet light rail tracks to enable project completion during the dry-weather season. Crews are currently working from 7 a.m. to 6 p.m.
Pre-Construction Activities 2018: The contractor for this project, James W. Fowler Co., conducted closed circuit television (CCTV) inspections and 3D laser profiling of the Outfall tunnel in the fall of 2018, which allowed the City to confirm existing conditions, create a profile of the sewer's interior, and then order the materials needed to repair the Outfall.
Mobilization in October 2019: During the fall of 2019, the city's contractor completed repairs to the small-diameter (58 to 84-inch diameter) pipe sections in SE 16th Avenue and in SE Tibbetts Street.
Re-mobilization in Spring of 2020: Crews mobilized again in March 2020 when weather permitted them to work safely inside the tunnel. This phase of work includes repairs to the large-diameter (118 to 120-inch diameter) pipe sections between SE 16th Avenue and the Willamette River.
Accomplishments in 2020: Crews have completed the following work:
Environmental Services is repairing about 3,700 feet of the Taggart Outfall sewer tunnel, which measures from 58 to 120 inches in diameter and from 20 to 75 feet deep.
The Taggart Outfall project is not a typical sewer construction project. There is very little aboveground construction activity and no digging in streets. Crews conduct repair work from inside the sewer tunnel deep underground.
The primary construction methods to repair the Taggart Outfall are Slip Lining and Tunnel Liner Plate. Crews enter the sewer tunnel from maintenance access holes and a sewer access shaft and climb down 30 to 75 feet below the surface. Working from a locomotive on a steel track laid inside the tunnel, crews are essentially constructing a new sewer inside the old brick sewer.
They are constructing some sections by inserting a fiberglass-reinforced pipe liner inside the tunnel. They are constructing other sections by assembling new steel liner plates in place inside the tunnel. They then fill the space between the new sewer and the old brick sewer with grout. These methods avoid digging trenches in the roadway and reduce aboveground impacts to the traveling public and adjacent properties.
For safety, crews can only work inside the tunnel on dry days when there is no water flowing into the tunnel. In the event of rainfall or a sudden surge of stormwater flowing into the tunnel, crews and equipment must be removed quickly from the sewer tunnel, and completion of repairs may be delayed.
Tunnel fans are necessary to provide ventilation to crews working in the confined space of the sewer tunnel deep underground. The fans must operate all hours and all days when crews are inside the tunnel.
The major sources of noise will be the vactor trucks, grout pumps, generators, forklifts, and tunnel fans. The contractor will be required, by contract, to use quiet generators. Mitigation measures are incorporated into the construction contract. These mitigation measures are the following:
While there will be some equipment and materials aboveground, most of the work will be conducted belowground inside the sewer tunnel. You can expect the following activities and impacts:
Environmental Services will work directly with the community throughout the course of the project. Community outreach staff will listen to your suggestions and respond to your concerns. We encourage you to:
In the event of a sewer backup or basement flooding, call the Maintenance hotline immediately at 503-823-1700. It is staffed all hours and all days, 24/7.