Geothermal Energy: Operations and Maintenance ImpactsEnvironmental impacts during the operations and maintenance phase would mostly occur as a result of noise, water demand, waste management, land use conflicts, potential spills, and the increased traffic at the project site.Typical activities during the operations and maintenance phase include operation and maintenance of production and injection wells and pipeline systems, operation and maintenance of the power plant, waste management, and maintenance and replacement of facility components. Potential impacts from these activities are presented below, by the type of affected resource.Acoustics (Noise)Primary sources of noise during normal operations would be associated with the power plant, e.g., the power houses, transformers, and cooling towers. Cooling towers are relatively tall and have noise-generating fans at the top, making them the main source of noise. During the operations and maintenance phase, a geothermal power plant would generate noise levels in the 71 to 83 decibel range at a distance of one-half mile. Noise levels can be reduced by the addition of mufflers or other soundproofing. The primary impacts from noise would be localized disturbance to wildlife, recreationists, and residents.Air QualityEmissions generated during the operations and maintenance phase include exhaust from vehicular traffic and fugitive dust from traffic on paved and unpaved roads, most of which would be generally limited to worker and maintenance vehicle traffic. In addition, emissions could include the release of geothermal fluid vapors (especially hydrogen sulfide, carbon dioxide, mercury, arsenic, and boron, if present in the reservoir). Impacts would depend upon the amount, duration, location, and characteristics of the emissions and the meteorological conditions (e.g., wind speed and direction, precipitation, and relative humidity). Carbon dioxide emissions would be considerably less than for comparable power plants using fossil fuel. State and local regulators may require permits and air monitoring programs.Cultural ResourcesDuring the operations and maintenance phase, impacts to cultural resources could occur primarily from unauthorized collection of artifacts and from visual impacts. In the latter case, the presence of the aboveground structures could impact cultural resources with an associated landscape component that contributes to their significance, such as a sacred landscape or historic trail. The potential for indirect impacts (e.g., vandalism and unauthorized collection) would be greater during the operations and maintenance phase compared to prior phases, due to its longer duration.Ecological ResourcesMost impacts to ecological resources (vegetation, wildlife, aquatic biota, special status species, and their habitats) would be less during the operations and maintenance phase than for the exploration and drilling and construction phases because no new drilling or construction activities would take place. However, operations and maintenance activities have the potential to affect ecological resources mainly by reducing the acreage for foraging and migrating animals, fragmenting habitat, and creating noise at the project site during the life cycle of the project (which could last up to 50 years). Some of these impacts could be significant. Increased human activity also increases the risk of fire, especially in arid or semiarid areas. Applications of herbicides to control vegetation along access roads, buildings, and power plant structures, would increase the risk of wildlife exposure to contaminants.Environmental JusticePossible environmental justice impacts during the operations and maintenance phase include the alteration of scenic quality in areas of traditional or cultural significance to minority populations. Noise, water, and health and safety impacts are also potential sources of disproportionate effects to minority or low-income populations.Hazardous Materials and Waste ManagementIndustrial wastes are generated during routine operations and maintenance activities (e.g., lubricating oils, hydraulic fluids, coolants, solvents, and cleaning agents). These wastes are typically placed in containers, characterized and labeled, possibly stored briefly, and transported by a licensed hauler to an appropriate permitted off-site disposal facility as a standard practice. Impacts could result if these wastes were not properly handled and were released to the environment. Environmental contamination could occur from accidental spills of herbicides or, more significantly, oil. Chemicals in open pits used to store wastes may pose a threat to wildlife and livestock.Health and SafetyPotential human health and safety impacts during the operations and maintenance phase would include exposures to geothermal fluids or steam during maintenance activities, system failures or well blowouts, and hazardous materials such as petroleum, oils, lubricants, and herbicides; and the risk of serious injuries or accidents. Adverse impacts could also occur from the risk of electrical fires and wildfires caused by project activities; electric shock during transmission line and substation maintenance; 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 UseImpacts on land uses during the operations and maintenance phase are an extension of those that occurred during the exploration and drilling and construction phases. While, to some extent, land use can revert to its original uses (e.g., livestock grazing), many other uses (e.g., mining, farming, or hunting) would be precluded during the life span of the geothermal development. Mineral resources would remain available for recovery and operations and maintenance activities are unlikely to affect mining and energy development activities, military operations, livestock grazing, or aviation on surrounding lands.Paleontological ResourcesThe potential for impacts on paleontological resources would be limited primarily to unauthorized collection of fossils. This threat is present once the access roads are constructed, making remote areas more accessible to the public. Damage to localities caused by OHV use could also occur. The potential for indirect impacts (e.g., vandalism and unauthorized collection) would be greater during the production phase compared to the drilling/development phase, due to the longer duration of the production phase.SocioeconomicsActivities during the operations and maintenance phase would contribute to the local economy by providing employment opportunities, monies to local contractors, and recycled revenues through the local economy. The magnitude of these benefits would vary depending on the resource potential. Operations of a typical 50-MW power plant and related transmission lines would require an estimated 93 jobs and $8 million in income, but would vary depending on the community. Job availability would vary with different stages of construction. Expenditures for equipment, materials, fuel, lodging, food, and other needs would stimulate the local economy over the duration of the project, which could last up to 50 years.Economic impacts may occur if other land use activities (e.g., recreation, grazing, or hunting) are altered by geothermal development. Constructing facilities will alter the landscape and could affect the nonmarket values of the immediate area during the life of the geothermal development. Many of these land uses may be compatible; however, it's possible that some land uses will be displaced by geothermal development.Soils and Geologic ResourcesImpacts to soils and geologic resources would be minimal during the operations and maintenance phase. The initial areas disturbed during the construction phase would continue to be used during standard operation and maintenance activities, but no additional impacts would occur unless new construction projects or drill sites are needed. Impacts associated with new construction projects or drill sites would be similar to those described for the exploration and drilling and construction phases.TransportationDaily traffic levels, particularly heavy truck traffic, would be expected to be lower during the operations and maintenance phase compared to other phases of geothermal development. For the most part, heavy truck traffic would be limited to periodic monitoring and maintenance activities at the well pads and power plant.Visual ResourcesAdverse impacts to visual resources would occur during the 10- to 30-year life of the geothermal development. Impacts during the operations and maintenance phase would result from the presence of facility structures and roads (where undeveloped land once stood), increased vehicular traffic to the site, and releases of steam plumes from the geothermal power plant. Periodic construction projects occurring throughout the life of the development would have impacts similar to those described for the construction phase.Water Resources (Surface Water and Groundwater)Impacts to water resources during the operations and maintenance phase result mainly from the water demands associated with operating a geothermal power plant. Water resources during operations would be needed for replenishment of the geothermal reservoir through reinjection. However, because some water would be consumed by evaporation, additional water would need to be added to the system from another source. Makeup water to replace the evaporative losses and blowdown in a water-cooled power plant system would also be needed, depending on the type of power plant used (e.g., flash steam facilities can lose up to 20% of its cooling water due to evaporation, but binary plants are nonconsumptive because they use a closed-loop system). Water can also be lost due to pipeline failures or surface discharge for monitoring and testing the geothermal reservoir. The availability of water resources could be a limiting factor in siting or expanding a geothermal development at a given location.Cooling water or water from geothermal wells that is discharged to the ground or to an evaporation pond could affect the quality of shallow groundwater if allowed to percolate through the ground. However, the potential for this type of impact is considered minor or negligible because the facility would have to comply with the terms of the discharge permit required by the state.