Plymouth Street 48-inch Bypass Repair Project

Project details last updated June 24, 2019

Following the heavy rainstorm in early February 2019, a 48-inch bypass drain line on Plymouth Street near the City of St. Helens’ Wastewater Treatment Plant collapsed, causing a portion of the road to cave in. This bypass line is used as an emergency overflow bypass for the Wastewater Treatment Plant’s secondary lagoon and picks up stormwater on South 6th Street and on Plymouth Street east of South 7th Street.

St. Helens Public Works Department closed Plymouth Street east of the treatment plant to vehicles and pedestrians to ensure everyone’s safety and our Engineering Department immediately began working on a repair project.

Because the pipe is so large and our Public Works Department doesn’t own equipment large enough to complete the full project on its own, our Engineering and Public Works crews have been working with Turney Excavating, Inc. on the repair project.

The City’s Engineering Department was able to source materials for the project locally with Cascade Concrete Products based in Scappoose supplying the manhole and Contech Engineering Solutions out of Hillsboro supplying the new polymer-coated corrugated steel pipe (CSP) for the project. This new pipe has a 100-year life span. It was especially chosen because of its longer service life and for its cheaper installation costs. The old pipe that collapsed was uncoated corrugated metal pipe (CMP) which has a service life of 50 years and was installed in 1972.  

The goal is to have this project completed and the road reopened before July 4 so that the community will be able to fully access the St. Helens riverfront for the City’s annual Independence Day celebrations.

June 24, 2019 Update

A City contractor is completing Plymouth Street paving on Monday, June 24. It is anticipated that the road will be fully reopened by Tuesday, June 25.