Geological earthwork

Learn when a project may require a geotechnical investigation and how to request our nationally known services in geotechnical engineering and engineering geology expertise.

Requirements for a geotechnical investigation

Your project will likely need a geotechnical investigation and design if it involves:

  • Significant cuts and/or fills
  • Unstable ground (e.g., landslides, rockfall areas)
  • Crossing wetlands or otherwise soft ground
  • Structures such as bridges, retaining walls, or large hydraulic/drainage structures

Request a geotechnical investigation

To request an investigation contact Ioanna Kladou.

Start early to prevent potential delays. It could take two to six months to complete the work depending on the following:

  • Federal, state and local permit requirements
  • Right of entry needs
  • Overall project complexity
  • Timely availability of the necessary site data from the region project office
  • Overall Geotechnical Services workload

Geotechnical services

By providing the following services, we ensure that the soil or rock beneath the ground surface can support the loads and conditions placed on it during road construction and maintenance:

  • Subsurface field investigations
  • Geologic site characterization
  • Laboratory testing of soil and rock
  • Structure foundation and retaining wall design
  • Soil cut and fill stability design
  • Rock slope design
  • Unstable slope management
  • Unstable slope mitigation due to rock fall, landslides, debris flow, etc.
  • Material source evaluation (pits and quarries)
  • Long-term site monitoring for geotechnical engineering purposes
  • Support to regional construction staff regarding geotechnical issues and contractor claims
  • Support to regional maintenance staff when geotechnical problems occur such as landslides, rock fall, earthquake or flood damage


166,800 electric vehicle

registrations in Washington in 2023, up from 114,600 in 2022.

87 wetland compensation sites

actively monitored on 918 acres in 2023.

25,000 safe animal crossings

in the Snoqualmie Pass East Project area since 2014.