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Project Spotlight: Pump Station 43 Emergency Force Main Replacement Project

Just west of the Ballard Locks, nearly 50 feet below the floor of the Ship Canal, Seattle Public Utilities (SPU) recently installed a new sewer force main to bring flows from the north side of the waterway to the south to be discharged into the King County Lawton Tunnel and ultimately conveyed to King County’s West Point Treatment Plant.

In the fall of 2017, SPU discovered that the existing sewer force main connected to Pump Station 43 in Ballard was damaged. We took immediate action to bypass the pipe and minimize sewage from flowing into the waterway. After further investigation, crews found that the pipe was significantly cracked, had large holes, and was badly corroded. Instead of attempting multiple, short-term spot repairs, we decided to replace the entire force main in order to provide reliable sewer service to residents well into the future and to better protect aquatic habitat and public health.

Construction began in January 2019 and should be complete later this summer. Earlier this year, SPU’s contractor mobilized two large horizontal drilling rigs to the site to drill a borehole underneath the waterway for the new sewer pipe. If you’ve driven near the 5500 block of Seaview Ave NW in Ballard, or the 3500 block of W Commodore Way in Magnolia recently, you may have seen our crews working in the right of way (thanks for your patience during these traffic impacts!).

In March, the contractor reached a huge milestone when the new 1,000-plus-foot-long sewer pipe was pulled into the borehole.

Over the next few months, the contractor will begin installing new vaults to serve the force main, removing the temporary sewer bypass that’s been on-site since November 2017, and connecting the new sewer pipe to the existing King County Lawton Tunnel system in Magnolia.

“It’s exciting to get to this point in the project,” Jade Sullivan, SPU Construction Manager said. “This is a huge investment in our sewer system and allows SPU to provide reliable, sustainable sewer service to these communities while providing a cleaner, healthier habitat for salmon.”

To learn more about the Pump Station 43 Emergency Force Main Replacement project, please visit