OR18 Newberg-Dundee Bypass Phases I and II

GRI provided geotechnical services and geologic consultation and design services for this 4-mile-long project that includes 10 bridges and a 1,500-foot-long mechanically stabilized earth retaining wall. GRI provided services for six bridges and the MSE wall. Portions of the alignment are located near steep slopes at the edge of the Willamette River and several tributary streams. GRI evaluated lidar data publicly available through DOGAMI to evaluate landslides along the alignment, which disclosed several significant landslides that were unrecognized in previous ground-based studies completed by others. At the time of design, it was the largest roadway transportation project underway in Oregon. GRI’s work has included deep exploration borings, laboratory testing, engineering analyses to address deep foundation design, retaining wall design, landslide evaluation and repair, and assisting ODOT with drafting requirements. Cyclic testing of Willamette silt soils by GRI was used to demonstrate that the liquefaction hazard would be low during the design-level earthquake, thereby saving several million dollars of ground improvement costs originally anticipated by ODOT.

Phase II of the Newberg-Dundee Bypass project entails the addition of a new roadway alignment that extends from the newly constructed Phase I, connecting OR219 and OR99W. Improvements include an intersection change at the bypass connection, five new bridge structures, embankment design, the addition of a two-lane highway, cross over bridge(s), sound wall, sound and retaining walls, stormwater improvements, and traffic signaling. Phase II will be delivered in four separate PS&E packages.

As part of Phase II Newberg-Dundee Bypass, GRI is providing geotechnical, hazmat, and pavement design services for this project, including field explorations, laboratory testing, and geotechnical engineering services to aid in the design of the proposed improvements. GRI will also be conducting a landslide investigation for the entire alignment.

Location: Yamhill County, Oregon

Owner: ODOT

Market Sector: Transportation