Skip navigation
Tribal Energy and Environmental Information Clearinghouse
Tribal Energy and Environmental Information Clearinghouse: Environmental resources for tribal energy development
Energy Resources Assessments & Monitoring Laws & Regulations
Energy Resources Assessments & Monitoring Laws & Regulations |  Home  |  News  |  FAQ  |  Glossary
Document Library
Federal and Tribal Contacts

Soils and Geological Resources (including Seismicity and Geological Hazards) Mitigation Measures

Mitigation measures to avoid or reduce impacts to soils and geological resources from geothermal energy development.

The following are examples of mitigation measures that could be applied to reduce impacts to soils and geological resources from site- and project-specific conditions. Impacts to soils and geological resources are related to the project footprint (e.g., land disturbance, erosion) and the extraction of raw materials for project use. Many impacts can be reduced or avoided when considered during the siting and design phase.

Develop a final set of mitigation measures for any project in consultation with the appropriate federal resource management agencies and stakeholders. Conduct these consultations early in the project development process and preferably prior to final project siting and design.

Siting and Design Mitigation Measures

Siting and design considerations that mitigate impacts include:

  • Identify and avoid unstable slopes and local factors that can cause slope instability (e.g., groundwater conditions, precipitation, seismic activity, slope angles, and geologic structure).
  • Minimize the amount of land to be disturbed as much as possible. Use existing roads and borrow pits and quarries. Minimize vegetation removal.
  • Place access roads to follow natural topography and avoid or minimize side hill cuts. New roads should avoid going straight up grades in excess of 10%. Design roads with eventual reclamation in mind.
  • Design runoff control features to minimize soil erosion.
  • Construct drainage ditches only where necessary. Use appropriate structures at culvert outlets to prevent erosion.
  • Use special construction techniques in areas of steep slopes, erodible soils, and stream crossings.
  • Perform a detailed geotechnical analysis prior to construction activities so structures are sited to avoid any hazards from subsidence or liquefaction.

General Mitigation Measures

General mitigation practices and principles that could apply to any or all phases of a geothermal energy development project include:

  • Reclaim or apply protective covering on disturbed soils as quickly as possible.
  • Apply erosion controls relative to possible soil erosion from vehicular traffic and during construction activities (e.g., jute netting, silt fences, and check dams).
  • Maintain vegetative cover within road rights-of-way (ROWs) to prevent erosion and periodically monitor ROWs to assess erosion.
  • Clean and maintain catch basins, drainage ditches, and culverts regularly.

Project Phase-Specific Mitigation Measures

Mitigation measures specific to a particular phase of a geothermal energy project include:

Construction Practices

  • Save topsoil removed during construction and use to reclaim disturbed areas upon completion of construction activities.
  • Avoid creating excessive slopes during excavation and blasting operations.
  • Obtain borrow material from authorized and permitted sites.
  • Dispose of excess excavation materials in approved areas to control erosion and minimize leaching of hazardous materials.
  • During all phases of the project, keep equipment and vehicles within the limits of the initially disturbed areas.
  • In areas of potential wind erosion, apply gravel to access road surfaces.

Decommissioning/Site Reclamation

  • Use topsoil removed during decommissioning activities to reclaim disturbed areas.
  • Backfill any foundations and trenches, preferably with excess excavation material generated during construction.
  • Reestablish the original grade and drainage pattern to the extent practicable.
  • Use weed-free native shrubs, grasses, and forbs to stabilize all areas of disturbed soil.