LOCATION: City of Astoria, Oregon
PROJECT PARTNERS:
- Owner: City of Astoria
- Engineer: MWH
- Materials Supplier: Layfield
- Installation: Layfield
THE CHALLENGE
The City of Astoria operates two uncovered potable water reservoirs that required covering to meet EPA and AWWA standards. Issues such as birds, frogs, and debris landing in the reservoirs were common. After evaluating several options, the City decided on a HypaFlex® (CSPE) floating cover for Reservoir #3, which needed a 163,355 sq. ft. cover, a 165,000 sq. ft. liner, and a 16,250 sq. ft. baffle curtain.
One of the biggest challenges was the weather and time constraints. Due to extended wet seasons along the Oregon Coast, the liners and covers could only be installed in the summer months. Once the reservoir was drained, Layfield had 90 days to complete the installation.
Unexpected sub-grade work was needed on the 20-year-old reservoir floor, which added additional pressure to the already tight schedule. Layfield completed the floor repairs in two weeks, allowing the project to stay on track.
THE SOLUTION
Layfield recommended a potable-grade 45 mil HypaFlex® (CSPE) geomembrane for the floating cover, which meets NSF61 potable water specifications. The construction work was publicly tendered, and Layfield was selected as the General Contractor for the project, responsible for the fabrication and installation of the liner, floating cover, baffle curtains, and appurtenances.
To address the City’s concern about stagnant water, Layfield installed a baffle curtain under the floating cover, which directed water in a serpentine path, improving chlorine mixing time and reducing stagnant water in the reservoir.