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Over the last month, the Willamette Water Supply Program (WWSP) Raw Water Facilities (RWF) team successfully achieved two significant construction milestones at the project site in Wilsonville.
In May, the existing 42-inch raw water header at the Willamette River Water Treatment Plant (WRWTP) was cut and capped to enable work for the Willamette Water Supply System (WWSS) pipeline to proceed. The header is the pipe that collects water from the raw water pumps and delivers it to the WRWTP. This modification will allow the existing WRWTP raw water pumps to operate separately from the future WWSS raw water pumps. This work required a carefully planned shutdown of the WRWTP for 10.5 hours. Since the WRWTP is the primary source of potable water for Wilsonville and Sherwood, the WWSP team prepared contingency plans to address anticipated construction challenges during the shutdown. The shutdown and work were completed ahead of schedule and passed all inspections.
Several weeks later, the team completed the trenchless crossing of Arrowhead Creek. Using a technique called pipe ramming, the crew pushed an 84-inch diameter, 1.25-inch-thick steel casing pipe through the ground below Arrowhead Creek using one of the largest hydraulic pipe-ramming hammers available in the U.S. The activity was in a geologically challenging area with the potential to encounter boulders or other unknown conditions, complicating the work. The trenchless crossing was successfully completed according to the plan and without incident.
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