Public Construction

Marysville Waste Water Treatment Plant
Photo courtesy ABC of Western Washington
IMCO General Construction installed 153 concrete piles to support an expansion of the Marysville Waste Water Treatment Plant.

IMCO General Construction

Marysville Waste Water Treatment Plant

Owner: City of Marysville

Engineer: Tetra Tech/KCM

The second phase of the Marysville Waste Water Treatment Plant upgrade and expansion project was built by IMCO General Construction to make the facility more efficient.

The goal of the project was to bring effluent quality up to state Department of Ecology requirements. That was accomplished by installing 153 concrete piles, placing eight additional sand filters, constructing an ultraviolet disinfection system, retrofitting an existing concrete tank, and a number of other jobs.

The treatment plant site, located adjacent to Ebey Slough and surrounded by 20 acres of treatment lagoons, offered little room for material laydown and equipment storage. The 140-foot lengths of concrete pile specified by the engineer would have been difficult to store and transport to the site, so IMCO and Tetra Tech/KCM decided to split each pile into two sections and later connect them with steel splices. The shorter and lighter piles allowed crews to use a smaller crane to lift them, and made the operation safer.

IMCO simplified construction as crews were preparing to build the shoring for excavation for the sand filters. Geotechnical reports indicated that the ground was extremely saturated and unstable, requiring stout and complicated shoring to support construction of a sheet pile cell. IMCO crews found a photograph taken in 1994 of the excavation for the existing sand filters, showing an open-cut excavation with soils that appeared stable. With the blessing of the geotechnical engineer, IMCO performed a successful open-cut excavation, resulting in significant time savings and safer work access.

ABC members on the job included Wilder Construction Co., Andgar Corp. and General Storefronts.

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