North Twin BridgeGeolocation: 47.4018, -122.3243

Terracon was contracted to provide geotechnical services to assess site conditions at the North Twin Bridge in Des Moines, Wash. The bridge was built in 1950 and is about 230 feet long, spanning a steep sided ravine above McSorley Creek. During initial observations of the site, a void was discovered below the foundation of Bent 1. Terracon evaluated the existing foundation support conditions at Bent 1 and provided recommendations for methods for emergency foundation repair. Additionally, Terracon also provided options for seismic retrofit intended to upgrade the bridge to a performance based seismic retrofit Category D.

Des Moines, WA


Associated Office

SeattleGeolocation: 47.8005, -122.3181
The Seattle office provides multiple related service lines to clients at local, regional, and national levels. In the Northwest, Terracon specializes in geotechnical engineering, environmental consulting, and construction materials engineering and testing services. Terracon's basic strength is our commitment to our local clients; we are proud of our commitment to the Northwest region. The senior engineering staff of Terracon's Washington offices offers more than 250 years of local experience.
After operating in the greater Seattle area and Portland, Ore., since 1998, Zipper…