April 16, 2020

Century-old bridge to be replaced over Spokane River

Images courtesy of city of Spokane [enlarge]

The new bridge will retain the two concrete arches of the 1917 bridge.

[enlarge]

A 54-inch-diameter sewer pipe hanging off the side of the bridge will be replaced with two smaller pipes tucked between the arches.

The city of Spokane is about to start rebuilding the Post Street Bridge, which sits between two sets of falls on the Spokane River near Riverfront Park and downtown. The reinforced concrete open spandrel deck bridge was originally built in 1917 and was closed to motor vehicles last year due to structural concerns.

Marlene Feist, director of strategic development for the city's public works department, said the 330-foot-long bridge's twin concrete arches will be retained and the rest of it replaced. A 54-inch-diameter sewer pipe that has hung off the side of the bridge for decades will be replaced with two smaller-diameter pipes placed mostly out of sight between the two arches.

Feist said engineers found that the bridge's arches are structurally intact but need some work, such as cleaning and crack sealing. Also, some internal steel may have to be replaced.

The city originally set up the $20 million project using the design-build contracting process, but costs didn't fall within budget last year so the city reissued it as a traditional low-bid job. Feist said tariffs partially affected the cost last year but construction prices have eased up a bit since then.

The design-build team was led by KPFF Consulting Engineers and Kiewit. KPFF was retained as the designer and the project rebid with Garco Construction's $18 million low bid beating the other bidder, Max J. Kuney Co.

Feist said the city has held off awarding the contract to Garco until a few items are clarified. She said the project will likely start in May or June and finish in early 2022.

The new bridge will carry one northbound lane of traffic, with the other half reserved for pedestrians and bicyclists.

Feist said the bridge is popular with walkers and bikers because it carries part of the Centennial Trail and is near Riverfront Park. It was reduced from two traffic lanes to one about five years ago due to demand from those users and weight limitations placed on the aging structure.

Feist said the biggest challenge to rebuilding the bridge will be protecting the river below and diverting walkers and bikers to another bridge about a block or two away.

Funding is coming from local and federal sources.