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Ecological Resources Mitigation Measures

Mitigation measures to avoid or reduce ecological impacts from geothermal energy development.

The following are examples of mitigation measures that could be applied to reduce ecological impacts from site- and project-specific conditions. Impacts to ecological resources are related to the project footprint (e.g., land disturbance, habitat destruction, erosion, changes in runoff patterns, and hydrological alterations), project emissions (e.g., fugitive dust, sediment runoff, air releases, water releases), and resource use (e.g., water extraction). 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:

  • Use existing facilities (e.g., access roads, parking lots, graded areas) to the extent possible to minimize the amount of new disturbance.
  • Review existing information on species and habitats in the project area. Contact appropriate agencies early in the planning process to identify potentially sensitive ecological resources that may be present in the project area.
  • Conduct pre-disturbance surveys and site facilities away from important ecological resources (e.g., wetlands, water bodies, important upland habitats, sensitive species populations).
  • Prepare a habitat restoration and site restoration plan to avoid (if possible) or minimize negative impacts on vulnerable wildlife while maintaining or enhancing habitat values for other species. The plan should identify revegetation, soil stabilization, and erosion reduction measures to be implemented to ensure that all temporary use areas are restored. The plan should require that restoration occur as soon as possible after completion of activities.
  • Minimize the amount of land disturbance and develop and implement stringent erosion and dust control practices.
  • Bury electrical supply lines in a manner that minimizes additional surface disturbance. Use overhead lines in cases where the burial of lines would result in further habitat disturbance.
  • Develop a plan for control of noxious weeds and invasive plants that could occur as a result of new surface disturbance activities at the site. The plan should address monitoring, weed identification, the manner in which weeds spread, and methods for treating infestations. Require the use of certified weed-free mulching. Prohibit the use of fill materials from areas with known invasive vegetation problems.
  • Develop a spill management plan.
  • Locate well pads outside of the 100-year floodplain.
  • Locate well pads and access roads to maintain existing stands of high-quality habitat and to maintain continuity between stands. Minimize the creation of, or increase in, the amount of edge habitat between natural habitats and disturbed lands.
  • Minimize the number of stream crossings when locating access roads. When stream crossings cannot be avoided, use fill ramps rather than stream bank cutting. Design stream crossings to provide instream conditions that allow for and maintain movement and safe passage of fish.

General Mitigation Measures

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

  • Educate workers regarding the occurrence of important resources in the area and the importance of protection.
  • Schedule activities to avoid disturbance of resources during critical periods of the day (e.g., night) or year (e.g., breeding season).
  • Instruct employees, contractors, and site visitors to avoid harassment and disturbance of wildlife, especially during reproductive (e.g., courtship, nesting) seasons. In addition, control pets to avoid harassment and disturbance of wildlife.
  • Avoid the spread of invasive nonnative plants by keeping vehicles and equipment clean and reseeding disturbed areas with native plants.
  • Limit pesticide use to nonpersistent, immobile pesticides and apply in accordance with label and application permit directions and stipulations for terrestrial and aquatic applications.
  • Apply spill prevention practices and response actions in refueling and vehicle-use areas to minimize accidental contamination of habitats.
  • Turn off all unnecessary lighting at night to avoid attracting migratory birds.
  • Use dust abatement techniques on unpaved, unvegetated surfaces to minimize airborne dust.
  • Regularly monitor the well pads, access roads, and ancillary facilities for invasive nonnative plant species establishment. Initiate control measures immediately upon evidence of invasive species introduction or spread.
  • Address spills immediately per the appropriate spill management plan, and initiate soil cleanup and soil removal if needed.

Project Phase-Specific Mitigation Measures

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

Exploration and Drilling/Development

  • Use explosives only within specified times and at specified distances from sensitive wildlife or surface waters as specified by state, tribal, or federal agencies.
  • Reduce habitat disturbance by keeping vehicles on established access roads or well pads and by minimizing foot traffic in undisturbed areas.
  • Establish buffer zones around raptor nests, bat roosts, and other biota and habitats of concern such as rare plants, if site studies show that proposed facilities would pose a significant risk to these species.
  • Maintain noise-reduction devices (e.g., mufflers) in good working order on vehicles and construction equipment.
  • Refuel in a designated fueling area that includes a temporary berm to limit the spread of any spill. Use drip pans during refueling to contain accidental releases and under fuel pump and valve mechanisms of any bulk fueling vehicles parked at the construction site.
  • If trucks and construction equipment are arriving from locations with known invasive vegetation problems, establish a controlled inspection and cleaning area to visually inspect arriving construction equipment to clean the vehicles to remove and collect noxious weed seeds that may be adhering to tires and other equipment surfaces.
  • Initiate interim site reclamation activities and invasive vegetation monitoring and control activities as soon as possible after construction activities are completed. Reclaim all disturbed areas not required for long-term operations using weed-free native shrubs, grasses, and forbs. Use locally designed seed mixes in re-vegetation/stabilization efforts.
  • As feasible, use closed containment systems rather than open pits to contain produced water and other wastes.
  • Use effective and proven wildlife deterrents or exclusionary devices for open pits (e.g., netting).

Operational Controls and Guidelines

  • Maintain all areas around facility structures in an unvegetated state (e.g., with crushed gravel), or with vegetation that does not support wildlife.
  • Depending on the ecological resources present, consider steps to minimize the amount of vehicular traffic and human activity. Use of pipeline collections systems and remote well site monitoring are examples of activities that might be employed.
  • Report observations of potential wildlife problems, including wildlife mortality, to the appropriate wildlife agency.
  • Use drip pans during refueling to contain accidental releases.

Decommissioning/Site Reclamation

  • Remove all facility and ancillary structures from the site.
  • Backfill any foundations, pits, and trenches, preferably with excess excavation material generated during prior ground-disturbing activities.
  • Use topsoil removed at the beginning of the project or during decommissioning activities to reclaim disturbed areas.
  • Reclaim all areas of disturbed soil using weed-free native shrubs, grasses, and forbs.
  • Restore vegetation cover, composition, and diversity to values commensurate with the ecological setting.
  • Review reclamation efforts and weed control periodically until the site is determined to have been successfully reclaimed.