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Geothermal Energy: Decommissioning and Site Reclamation Impacts

Potential environmental impacts from decommissioning and site reclamation activities are generally similar to those during the construction phase, but of shorter duration than those during the operations and maintenance phase.

Geothermal facilities are removed after their useful life in a process called decommissioning. Following decommissioning, the site would be restored (reclaimed) to approximate its original condition or to some standard that results in stable environmental conditions. Typical activities during the decommissioning/reclamation phase include closure of all facilities and wells; removal of aboveground components and gravel from well pads, access roads (if not maintained for other uses), and other ancillary facility sites; recontouring the surface; and revegetation. Impacts would be similar to those addressed for the construction phase; however, many of these impacts would be reduced by implementing good industry practices. Restoration during this phase would also ensure that impacts beyond the life of the geothermal energy development are avoided or minimized. Potential impacts from these activities are presented below, by the type of affected resource.

Acoustics (Noise)

Sources of noise during decommissioning would be similar to those during drilling and construction and would be generated primarily by construction equipment and vehicular traffic. Near residential areas, noise levels could exceed the EPA guideline but would be intermittent and extend for only a limited time.

Air Quality

Emissions generated by activities during the decommissioning and reclamation phase include vehicle emissions, diesel emissions from large construction equipment and generators, and dust from many sources such as land clearing, structure removal, cement mixing, backfilling, dumping, reclamation of disturbed areas (grading, seeding, planting), and truck and equipment traffic.

Cultural Resources

Decommissioning activities would have little potential to impact cultural resources because these resources would have been removed professionally prior to construction and drilling, or would have been previously disturbed or destroyed during previous phase activities. The unauthorized collection of artifacts could continue to be a problem if access roads were left in place, affording access to remote areas. Visual impacts of the geothermal development would be mitigated if the area was restored to its pre-development condition. However, despite the physical removal of the project, the impact of a scarred environment on an area considered sacred to Native Americans would likely remain.

Ecological Resources

Impacts to ecological resources from decommissioning and reclamation activities would be similar in nature to the impacts that would occur during construction and drilling, but at a reduced magnitude. There would be a temporary increase in noise and visual disturbance associated with the dismantling and removal of project facilities and reclamation. Impacts to wildlife habitat would be minimal, and injury and mortality rates of vegetation and wildlife would be much lower than they would be during construction and drilling. Removal of aboveground structures would eliminate the impacts to wildlife that occurred during operation (e.g., bird collisions and habitat fragmentation). Removal of sump pits would also eliminate a potential source of concern to wildlife species. Following site reclamation, the ecological resources at the project site could eventually return to preproject conditions depending on the end use selected for the project site. Grasses and forbs may be initially more plentiful during early years of reclamation than existed prior to project development. This could increase forage for some wildlife species. Reclamation of forest or sagebrush habitats could take decades or longer.

Environmental Justice

If significant impacts were to occur in any of the resource areas and these were to disproportionately affect minority or low-income populations, then there could be an environmental justice impact. Issues that could be of concern during decommissioning and site reclamation are noise, dust, and visual impacts; as well as reclamation of fish and wildlife habitats, which could benefit subsistence users.

Hazardous Materials and Waste Management

Substantial amounts of solid and industrial waste would be generated during the dismantling of geothermal structures and facilities. Much of the solid material can be recycled and sold as scrap or used for other projects; the remaining nonhazardous waste would be sent to permitted disposal facilities. Industrial wastes (oils, hydraulic fluids, coolants, solvents, and cleaning agents) would be treated similarly to wastes during the previous phases (e.g., put in containers, characterized and labeled, possibly stored briefly, and transported by a licensed hauler to an appropriate permitted off-site disposal facility). Impacts could result if these wastes were not properly handled and were released to the environment. If environmental contamination occurred at a site during the production phase, decommissioning and reclamation activities could include removal of the in situ contamination for transportation to an off-site disposal facility.

Health and Safety

Potential human health and safety impacts during decommissioning and reclamation would be similar to those during the exploration and drilling and construction phases; and relate to earthmoving, use of large equipment, dismantling of industrial components (power plant, substation, and pipeline systems), and transportation of overweight and oversized materials. Improperly closed sites can be a safety hazard. As with all phases of development, adverse impacts could also occur from the risk of electrical fires and wildfires caused by project activities and vehicular accidents due to increased traffic on local roads. The potential for such impacts can be minimized if appropriate safety procedures are implemented.

Land Use

Land use impacts resulting from drilling and construction could be largely reversed by decommissioning, depending on the end use selected for the project site. Grasses and forbs may initially be more plentiful during early years of reclamation than what existed prior to project development. This could increase forage for livestock.

Paleontological Resources

Decommissioning activities would have little potential to impact paleontological resources because these resources would have been removed professionally prior to construction and drilling, or would have been previously disturbed or destroyed during previous phase activities. The unauthorized collection of fossils could continue to be a problem if access roads were left in place, affording access to remote areas.


Direct impacts would include the creation of new jobs for workers during decommissioning and reclamation activities and the associated income and taxes paid. Indirect impacts are those impacts that would occur as a result of the new economic development and would include things such as new jobs at businesses that support the workforce or that provide project materials, and associated income and taxes. No adverse effect to property values is anticipated as a result of decommissioning. Site reclamation could result in economic values of residential properties adjacent to the geothermal development becoming equivalent to similarly developed residential areas that were not affected by industrial activities. The loss of royalty and tax revenue could adversely impact the local and regional economies.

Soils and Geologic Resources

Impacts to soils and geologic resources would be similar to those occurring during the construction phase. Dismantling and removing roads, well pads, the geothermal power plant, and structures related to the power plant (e.g., the pipeline system and transmission lines) would occur during this phase. These activities would cause topographic changes. Soil compaction due to decommissioning activities would reduce aeration, permeability, and water-holding capacity of the soils and cause an increase in surface runoff, potentially causing increased sheet, rill, and gully erosion. The excavation and reapplication of surface soils could cause the mixing of shallow soil horizons, resulting in a blending of soil characteristics and types. This blending would modify the physical characteristics of the soils, including structure, texture, and rock content, that could lead to reduced permeability and increased runoff from these areas. Soil compaction and blending could also impact the viability of future vegetation. It is unlikely that decommissioning or reclamation activities would activate geologic hazards. However, altering drainage patterns could also accelerate erosion and create slope instability.

Contaminated soils (e.g., in sump pits) would need to be removed, bioremediated, or treated in some other manner. Special soils such as biological or desert crusts could take from 50 to 300 years to recover from the damage caused by heavy equipment. Impacts to geologic resources would not be expected. All surface disturbances could possibly remain as long-term (or even permanent) impacts on the landscape if reclamation efforts are not successful.


Short-term increases in the use of local roadways would occur during decommissioning and reclamation. Overweight and oversized loads could cause temporary disruptions to local traffic.

Visual Resources

Decommissioning activities would have only temporary and minor visual effects, resulting from the presence of workers, vehicles, and construction equipment (including lighting for safety); and from vegetation damage, dust generation, scarring of the terrain, and altering landforms or contours as structures are dismantled and removed. Reclamation to restore visual resources to pre-disturbance conditions would lessen these impacts.

Water Resources (Surface Water and Groundwater)

The decommissioning and reclamation phase would involve ground-disturbing activities (related to dismantling facility structures and recontouring the surface) that could lead to an increase in soil erosion and surface runoff. Impacts to surface water would be moderate but temporary and could be reduced by implementing best management practices based on stormwater pollution prevention requirements and other industry guidelines.

Activities during this phase also include plugging and capping of production and injection wells. Improper abandonment could allow wells to serve as pathways for geothermal fluids to migrate to other aquifers, affecting both the geothermal resource and the quality of the affected aquifers. Proper well closure and capping would reduce the risk of these impacts.

Water would be also be used to control dust from road traffic and for consumptive use by workers. Depending on availability, it may be trucked in from off-site or obtained from local groundwater wells or nearby municipal supplies.

Upon completion of decommissioning, water consumption associated with the facility operations would end and disturbed areas would be contoured and revegetated to minimize the long-term potential for soil erosion and water quality related impacts.