The Portland General Electric (PGE) Cascade Crossing Transmission Project was a proposed 215-mile-long, 500-kilovolt (kV) transmission line between the Willamette Valley and Boardman, Oregon.

GRI provided engineering geology and geotechnical engineering services for the project. GRI’s work included a desktop geologic study, on-the-ground geologic reconnaissance of accessible portions of the alignment, and characterization of geologic and seismologic conditions along the project in support of the permitting process. This work addressed potential geotechnical concerns, such as seismic hazards, landslides, access road construction, and challenging soils.

GRI completed an extensive evaluation of mapped faults in the vicinity of the alignment and conducted field examination of fault traces where they could be delineated. Other potential seismic hazards that were evaluated included slope instability, liquefaction, amplification of seismic energy, and rock toppling. GRI’s engineering analyses and reporting were supported by extensive use of GRI’s in-house GIS capabilities.

Location: Willamette Valley through Boardman, Oregon

Owner: Portland General Electric Co.

Market Sector: Energy

Services: Geotechnical Engineering, Geologic Hazards, Seismic Engineering