BulkTransmission/Geology and Minerals
Transmission Geology and Minerals
Geology and Minerals
Present, Potentially Affected
- BLM-NV-WN-ES-08-01-1310, NV-020-08-01 (Blue Mountain Geothermal Well Field and Power Plant EA)
- Barren Ridge Renewable Transmission (Barren Ridge Renewable Transmission Project Environmental Impact Statement)
- CA-96062042 (Fourmile Hill Geothermal Development Project Environmental Impact Statement (EIS) / Environmental Impact Report (EIR) for Geothermal/Power Plant, Geothermal/Well Field, Geothermal/Transmission)
- DOE-EA-1733 (Calpine Enhanced Geothermal Systems Project EA at Geysers Geothermal Area for Geothermal/Well Field)
- DOE-EA-1759 (EA for Geothermal/Exploration at Southwest Alaska Regional Geothermal Energy Project Naknek, Alaska)
- DOI-BLM-CA-ES-2013-002+1793-EIS (Casa Diablo IV Geothermal Development Project EIS at Long Valley Caldera Geothermal Area for Geothermal/Power Plant)
- DOI-BLM-NV-B020-2011-0026-EA (Clayton Valley Geothermal Exploration Project EA for Drilling and Well Testing)
- DOI-BLM-NV-B020-2012-0214-EA (Silver Peak Area Geothermal Exploration Project EA for Drilling and Well Testing for Geothermal/Exploration)
- DOI-BLM-NV-C010-2010-0006-EA (Gabbs Valley and Dead Horse Wells Geothermal Exploration Projects EA for Geothermal/Exploration)
- DOI-BLM-NV-C010-2010-0010-EA (EA at Coyote Canyon and Dixie Meadows for Geothermal/Exploration Drilling and Well Testing)
- DOI-BLM-NV-C010-2010-0016-EA (EA for Airborne Electromagnetic Survey at Patua Geothermal Project for Geothermal/Well Field, Geothermal/Power Plant)
- DOI-BLM-NV-C010-2011-0001-EA (Coyote Canyon Utilization Project EA for TGP for Geothermal/Power Plant)
- DOI-BLM-NV-C010-2011-0516-EA (EA for Thermal Gradient Holes at Dixie Meadows Geothermal Exploration Project for Geothermal/Exploration, Geothermal/Well Field)
- DOI-BLM-NV-C010-2012-0029-EA (Tungsten Mountain Geothermal Exploration Project EA for Geothermal/Well Field Drilling and Well Testing)
- DOI-BLM-NV-C010-2012-0050-EA (Wild Rose Geothermal Project EA for Geothermal/Well Field, Geothermal/Power Plant)
- DOI-BLM-NV-C010-2012-0051-EA (Coyote Canyon South Geothermal Exploration Project EA for Geothermal/Exploration)
- DOI-BLM-NV-CC-ES-11-10-1793 (Salt Wells Geothermal Energy Projects EIS for Geothermal/Power Plant Development Drilling)
- DOI-BLM-NV-CO10-2011-0501-EA (EA for Phase II Production Wells and Thermal Gradient Holes at Patua Geothermal Project for Geothermal/Well Field)
- DOI-BLM-NV-W010-2011-0001-EA (EA of the Leach Hot Springs Geothermal Exploration Project at Grass Valley Geothermal Area for Geothermal/Exploration, Geothermal/Well Field Drilling and Well Testing)
- DOI-BLM-OR-P000-2011-0003-EA (EA for Newberry Volcano Enhanced Geothermal System (EGS) Demonstration Project for Geothermal/Well Field)
- DOI-BLM-OR-P040-0021-EA (EA for Exploratory Wells at Midnight Point and Mahogany Geothermal Exploration Projects, Glass Buttes, Oregon for Geothermal/Exploration)
- EA for Well Field Development at Patua Geothermal Area - DOI-BLM-NV-C010-2011-00016-EA (EA for Phase II of Patua Geothermal Project for Geothermal/Exploration, Geothermal/Well Field)
- LLNV-WO1000-2009-0002-EA (EA for Observation Wells at Jersey Valley II Geothermal Exploration Project)
- NV-020-07-EA-01 (EA for Observation Wells at Jersey Valley Geothermal Exploration Project for Geothermal/Well Field, Geothermal/Exploration)
- NV-063-EA06-098 (Reese River Valley Geothermal Exploration Project Environmental Assessment)
Before transmission corridors and substations can be constructed, a geologic hazard and technical survey must be conducted. The United States Geological Survey (USGS) agency houses geological overviews of the United States, however for a specific area evaluation, each state has a geological survey agency to conduct site reviews and access historical maps. This comprehensive survey gathers data on several categories.
These surveys determine the compatible engineering approaches for the area’s geologic properties. Surface conditions are assessed for landslides, slope instability, earth and debris flows, and ground disturbances by reviewing geologic and aerial maps. To obtain subsurface information, data is collected from water well logs, soil samples, and existing data from nearby transmission projects. Each proposed tower location is independently evaluated to determine slope stability.
Geology and Minerals Impacts & Mitigation
Geologic properties determine geologic hazards and avoidance areas to enable the project’s corridor. Some areas may be more susceptible to landslides, unstable slopes, or subsistence than other areas. Historic or active mines pose safety hazards and impact transmission line site selection. Mines may also be discovered after construction has begun.
The following outlines typical impacts and mitigation measures:
- To mitigate site hazards, avoid areas where ground shaking, liquefaction, landslides, karst subsistence, groundwater withdrawal, underground mining, historic mining, and active mining occur. The technical and hazardous geological survey identifies these areas.
- If active mines cannot be avoided, review whether or not project facilities will obstruct mineral resource access or pose safety threats to employees or private landowners.
- Relocate towers and roads if they are proposed within active landslides, bedrock hollows, or other geologic hazard areas.
- Identify unstable slopes or local factors that could induce slope instability to mitigate unforeseen project consequences.
- Develop a contingency plan for unavoidable geologic hazard areas to decrease potential pipeline spill impacts or project failure when connected to the grid.
- To decrease landslide hazards, refrain from constructing towers and substations in these areas. If construction is unavoidable, mitigate landslides by excavating unstable material to even the slope, removing driving forces near the landslide’s top, constructing retaining walls, adding stabilization fills, and installing rock bolts or wire mesh along the rock face.
- Control runoff and erosion by installing ditches, water bars, cross drainages, or roadside berms
- Follow the natural topography and land contour to mitigate large cut and fill slopes.
- Avoid sand dune areas to mitigate erosion and potential tower relocation.
- Utilize existing access roads to decrease surface disturbance and total number of acres needed to undergo the geologic survey.
- To decrease erosion, equip new access roads with appropriate drainage dips, side ditches, slope drains, and velocity reducers.
- Stabilize excess soil or disperse it around tower construction sites. During grading operations, minimize soil side casting.
- Design tower foundations to reduce the potential for soil settlement and compaction.
- During construction, coordinate with mine owners and operators to avoid peak mining season and high volume, earth-moving periods. Operational mitigation includes spanning the mine.
- To mitigate subsistence, review tower and substation final locations with mine owners and operators.