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Public works

Photo courtesy of MidMountain Contractors

The Beacon Hill Reservoir’s base and roof slabs were poured in a checkerboard pattern. There was a seven-day interval between adjacent pours to ensure the concrete would shrink sufficiently.

Beacon Hill Reservoir
replacement project

Location: Seattle

Owner/developer: City of Seattle

Project team: MidMountain Contractors, general and concrete contractor; MWH Americas, structural engineer; Cadman, ready-mix supplier

The Beacon Hill Reservoir replacement project is part of a city of Seattle program to cover open-air drinking-water reservoirs.

The program, which was started in 1997 to comply with health regulations, evolved to address security concerns following the terrorist attacks of Sept. 11, 2001.

The new cast-in-place concrete reservoir, built next to Jefferson Park, has the footprint of six football fields and a capacity of 50 million gallons. Its concrete lid is supported by 624 2-foot-diameter columns, and has been designed to withstand leaks and earthquakes.

Completing the structure required 28,000 cubic yards of ready-mixed concrete. The base and roof slabs were cast in a checkerboard pattern with a seven-day interval between adjacent pours to ensure the concrete would shrink sufficiently.

The lid will become part of a new 36-acre park area, currently under construction, with several natural-turf playfields.