MARYSVILLE — Each day, up to 150 trucks bring a dirt and crushed rock mixture from a Granite Falls quarry to Marysville to fill in four acres of the city’s sewage treatment lagoon.
They’ll bring in a total of 93,000 tons — enough to fill a football field 52 feet high. The work is part of the city’s $40 million upgrade of its sewage treatment plant, which includes construction of about four miles of pipeline to connect with Everett’s sewage system south of town. From there, sewage will go to Kimberly-Clark Corp.’s plant on Everett’s waterfront and then to a deepwater outfall in Possession Sound.
The filled portion of the lagoon will be the staging area for the pipeline project.
Marysville’s treatment lagoon is 72 acres. Built in 1959, it was expanded in 1980 and again in 1994 when the capacity was doubled to handle 6.1 million gallons per day, city spokesman Doug Buell said. Upgrades will increase its capacity to 12 million gallons per day and can be expanded to 20 million.
The project was mandated by the state Department of Ecology in 2000 because Steamboat Slough, where the city’s outfall is located, doesn’t get enough flow during summers to adequately dilute the effluent, reducing water quality.
A state loan will pay for the project. The city will recover the money through fees paid by developers and sewage customers.
The first phase of the project is almost done, Buell said. It involved adding aerators and mixers to the lagoon; upgrading the headworks, the machinery where the sewage enters the facility; cleaning solid particles out of the lagoon; raising the dike road; and putting in new pumps.
The second phase involves filling part of the south lagoon, putting in more sand filters to clean the water and remodeling a laboratory office adjacent to the public works headquarters on Columbia Avenue to add testing workstations.
In addition, workers will build a two-story maintenance building and a crane to move things around, two equipment bays, an equipment repair station, a boat storage area and more.
That phase is expected to be finished by the end of summer, city engineer Kevin Nielsen said.
In addition to the $20 million physical plant upgrades, the city will build the effluent pipeline in two phases.
The first, a $12 million open trench, is expected to begin in February and take about six months. It will be followed by a $4 million horizontal directional drill to get the pipeline under Ebey, Steamboat and Union sloughs and I-5. It’s thought to be the largest drilling of its type west of the Mississippi River and will take up to two months, he said.
The 15,000-foot trench will follow Highway 529 to Ross Road and then head south and east to connect with Everett’s sewage treatment plant.
The horizontal drill will be done last because it’s the most difficult. Workers will drill down up to 80 feet and cut a 42-inch hole for a 36-inch pipe to go through, Nielsen said.
"Once you start pulling the pipe, you can’t stop," he said, meaning that part will be an around-the-clock project.
Reporter Cathy Logg: 425-339-3437 or logg@heraldnet.com.
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