As part of the federal permanent injunction regarding culvert corrections, this $25-million design-build project corrected two fish barriers and replaced them with four fish passable structures.

Granite Construction Co. led the removal of the existing 400-ft-long culvert under I-5 and an adjacent frontage road and constructed two new bridge structures and a 56-ft-wide metal arch culvert. At another crossing, the team removed a double barrel box culvert on SR 11 and replaced it with a three-sided box culvert with a prestressed lid.

Work planning, pull schedules and constant collaboration across the entire job helped the Padden Creek Project reach completion under budget and 30 days ahead of the contract prescribed schedule in October 2022.

Photo by Elizabeth Novy

The Granite team developed a construction plan that allowed for short span, hollow core slab girders to be set directly on top of 12-ft-tall geosynthetic reinforced soil integrated bridge system (GRS/IBS) bridge abutments, which were perched on top of soldier pile walls with a shotcrete fascia.

After the new bridges were in service, Granite shifted I-5 traffic to its permanent configuration without interruption. The team excavated more than 20,000 cu yd of material, lagged more than 16,000 sq ft of wall face, hung more than 150,000 lb of rebar on the soldier pile and lagging walls and placed more than 600 cu yd of shotcrete fascia.

Photo by Nick English

Because of the Padden Creek Project’s success, the Washington State Dept. of Transportation is utilizing the same concept in 30% designs on other WSDOT design-build fish passage projects.

Both sites for this project are in highly traveled areas, so it was critical to establish safety plans that would protect not only the crews on site but also locals traveling in and around work zones.

Across 61,400 worker hours, the project saw zero recordable incidents or lost-time accidents. Through extensive work planning, the project team identified potential safety hazards and engineered them out of the design and the work plan prior to them ever being introduced in the field.

Photo by Nick English

During a record-breaking heat wave in summer 2021, workers were monitored constantly to ensure they were hydrated and took frequent breaks. The project team implemented alternative work hours while also providing several cooling stations and mandatory water breaks for the duration of the heat wave.