McClaine Street Improvements

Transforming a historic city street into an award-winning modern transportation corridor.

The rapidly growing City of Silverton, Oregon urgently needed to transform historic McClaine Street into a modern transportation corridor through the city. The project included new sidewalks, streetlights, bike lanes, sewer and stormwater systems, and improved access to businesses. A GeoEngineers team provided geotechnical services for the project as a subconsultant to Keller Associates.

Geotechnical conditions varied considerably along the length of the road alignment, with shallow rock anywhere from 2-15 feet below the surface. The rock included large boulders and other material that was difficult to blast or remove, and the GeoEngineers team prepared specific excavation recommendations for the contractor to follow.

Weather caused additional challenges during construction. A historic ice storm hit Oregon during the winter, knocking out the power for about two weeks and slowing down excavation. During the summer, nearby wildfires threatened the project and caused several temporary shutdowns. Through it all, GeoEngineers and the whole project team cooperated to solve each new challenge.


  • Project Planning and Coordination: GeoEngineers’ team coordinated with the city on right-of-way permitting, scheduling and other details.
  • Geotechnical Investigation and Testing: GeoEngineers was responsible for evaluating subsurface conditions, the existing roadway pavement and subgrade. The team completed seven drilled borings and seven dynamic cone penetrometer tests. Core samples were analyzed in an accredited GeoEngineers lab in accordance with ASTM International Standard Practices Test Methods.
  • Geotechnical Recommendations: GeoEngineers provided recommendations for excavation and construction, including subgrade preparation, placement and compaction of fill material, other earthworks, and wet weather contingencies for the highly moisture sensitive soils the team identified. Pavement construction and subgrade specifications were compliant with American Association of State Highway and Transportation Officials (AASHTO) and ASTM standards.
  • Pavement Design and Recommendations: The team evaluated subsurface conditions and existing roadway pavements, then provided pavement reconstruction recommendations based on a review of existing information, an on-site visual assessment, subsurface explorations, laboratory testing and engineering analyses.


Despite the challenges brought by extreme weather and variable subsurface conditions, GeoEngineers and the whole project team coordinated closely to finish sweeping renovations to McClaine Street on time and under budget. The McClaine Street corridor will provide the Silverton community with an efficient and modern route through the city that respects the street’s residents and history.

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