Pipeline project along 124th Ave./Tonquin Road begins
Construction crews are gearing up to begin laying pipe along 124th Avenue and Tonquin Road, part of a 30-mile pipeline that will eventually connect water pumped from the Willamette River to Hillsboro.
A 66-inch diameter pipe will soon be installed in the center of 124th Avenue and along both directions of Tonquin Road before the roadway is paved as part of the Willamette Water Supply Program, an ambitious partnership between the Tualatin Valley Water District and the city of Hillsboro.
Crews began building trench boxes the week of Oct. 10 and plans were to begin installing pipe on Oct. 23, according to Marlys Mock, media and community relations coordinator for the Willamette Water Supply Program.
When completed, the pipeline and water project will span through five cities in both Washington and Clackamas counties including Wilsonville, Tualatin, Sherwood, Beaverton and Hillsboro.
Already in the ground is some of the pipeline in the South Hillsboro portion of the city, an area that will eventually be home to 25,000 residents in Hillsboro.
Projections show the project coming in at or around $1 billion, making it one of the costliest infrastructure projects in state history, according to Willamette Water Supply Program officials.
The pipeline transmission project consists mostly of 44-inch- and 66-inch-diameter steel pipe. (During a recent tour, the sheer magnitude of the pipe's diameter was displayed when a workman was seen poking his head and torso inside a 44-inch pipe.)
The pipeline is made up of 50-inch-long pieces of pipe, each weighing an estimated 20,000 pounds, which are then welded togegther and buried in trenches between 13 to 20 feet deep, according to Andre Tolme, program construction manager for the Willamette Water Supply Program.
The pipes are then covered with crushed rock, sand and gravel, the aggregate produced by blasting the large rocks and boulders along 124th Avenue and then funneling them through a crusher. That produces about 200 yards a day of crushed rock, officials say.
Meanwhile, the main infrastructure project planned for 124th Avenue will be a large water treatment facility near Tualatin-Sherwood Road, which will handle from 60 million gallons of water a day with the potential to be expanded to handle 120 million gallons per day.
"That's to meet the long-term demand of Washington County," said Tolme.
Construction on the treatment facility is expected to begin in 2021 and will be up and running in 2026.
The facility is expected to withstand a major disaster, specifically, the Cascadia Subduction Zone earthquake, commonly referred to as "the big one," which is predicted for the Northwest sometime in the future.
Also planned as part of the Willamette Water Supply Program are two side-by-side water reservoirs on Cooper Mountain off of Grabhorn Road where the roadway takes a sharp left near Stone Creek Drive. That construction is planned in 2022.
Meanwhile, general road construction continues on and along Tonquin Road. Basalt Creek Parkway, which runs parallel to Tonquin Road, opened this summer with Washington County planning to open 124th Avenue in December 2018.