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Hydrokinetic Energy Facility Operations and Maintenance Impacts

Operations activities that may cause environmental impacts include operation of the hydrokinetic energy facility and associated maintenance activities.

Typical activities during the hydrokinetic energy facility operational phase include operation of the hydrokinetic energy devices, power generation, and associated maintenance activities that would require operations from a vessel or barge when components are being maintained, repaired, or replaced. Potential impacts from these activities are presented below, by the type of affected resource.

The following potential impacts may result from hydrokinetic energy facility operation.

Acoustics (Noise)

Underwater and above-water noise sources include ship and barge noise associated with transporting workers for maintenance activities, which would require frequent (and possibly daily) trips to the wave or tidal turbine energy farm or to the river in-stream turbines. Wave energy device noise would result from the flexing action of attenuators and point absorbers, from compressed air released from oscillating water column turbines, and from the impact of waves on terminators and overtopping devices. Underwater noise from the operation of tidal or river in-stream turbines is expected to be low because the rotational speed of the turbine blades is low. Overall, noise from operation of the hydrokinetic energy devices is expected to be low.

Onshore transformers would produce a humming noise and cooling fan noise. Sources of noise during operation of a barrage facility would be the turbines, generators, and transformers.

Air Quality (Including Global Climate Change and Carbon Footprint)

There are no direct air emissions from the operation of hydrokinetic energy facilities. Air emissions result from the operation of maintenance ship engines and on-ship equipment such as cranes, generators, and air compressors. Onshore vehicular traffic will continue to produce small amounts of fugitive dust and tailpipe emissions during maintenance activities. These emissions would not likely exceed air quality standards and impacts on air quality would be minor.

Cultural Resources

The operation and maintenance of offshore facilities would have no direct impact on cultural resources unless previously undisturbed areas are disturbed. Potential indirect impacts associated with the operation and maintenance of onshore facilities would be limited to unauthorized collection of artifacts made possible by access roads if they make remote lands accessible to the public. Visual impacts resulting from the presence of a large wave, tidal turbine, river in-stream energy facility, or barrage facility and transmission lines could affect some cultural resources, such as sacred landscapes or historic trails.

Ecological Resources

Wave and Tidal Energy Farms

The presence of a wave or tidal turbine energy farm could cause some marine mammals to avoid the area. Collisions with maintenance vessels and underground structures are anticipated to be rare. Overtopping wave energy devices could trap hatchling sea turtles and fish, resulting in injury or death. Impacts to the marine populations are expected to be minor to moderate depending on the specific site.

Some whale species migrate along the Pacific coast from 1.5 to 2 miles (2.5 to 3 km) offshore. Any wave or tidal turbine facility located in this zone could impact whale migration.

Noise levels from wave energy devices would be similar to those from ship traffic but would be continuous for the life of the wave farm. This could result in long-term avoidance by wildlife, which could lead to abandonment of feeding or mating grounds. Noise from submerged tidal turbines would be low due to the low rotational speed of the turbine blades.

Marine mammals, sea turtles, fish, and seabirds could be exposed to discharges or accidental fuel releases from maintenance vessels and to accidentally released solid debris. Such spills would be small and quickly diluted, and would not be expected to measurably affect these wildlife populations.

Depending on the design of the facilities, wave energy devices or any above-water portions of tidal energy devices could become the host for seabird colonies or may be used as haul out areas for seals and sea lions. Underwater structures may also create an artificial habitat for benthic species. This could complicate the maintenance and repair of wave energy devices.

Electromagnetic fields from the transmission cable can be detected by some fish and might result in attraction or avoidance. Such impacts would be negligible to minor.

Onshore impacts from operation could affect vegetation and wildlife by habitat reduction within the project site, access roads, and transmission line rights-of-way. Turtles nest along the south Atlantic and Gulf coastlines and nests and emerging hatchlings could be affected by maintenance activities onshore. Outdoor lighting from the onshore facilities could disorient the hatchlings and increase their exposure to predators.

River In-stream Facilities

Fish behavior is influenced primarily by the natural current in the river and only secondarily by the rotating mechanisms in the turbines. Proper location of the turbines would have minimal impact on fish movement or abundance. Allowance of sufficient turbine spacing in a turbine farm or in the river may minimize impact to fish. Noise generated by the turbines would have minimal effects on aquatic biota.

The turbines are not expected to affect terrestrial wildlife since they are mostly, or completely, submerged. Wildlife would be most affected by habitat reduction within the onshore project site, access roads, and transmission line rights-of-way. Impacts to wildlife are expected to be minor.

Barrage Facilities

Dam construction at a barrage facility would not increase the amount of wetted area inundated within the embayment, but it would alter the period of time that water is held in the embayment and could alter the aquatic environment of the embayment. These alterations could lead to habitat loss for terrestrial wildlife and bird species and/or degradation for aquatic species. Fish could be injured or killed during operation of the intake or during power generation. Because of a reduction in natural flushing of sediment, increases in sedimentation within the embayment may also adversely affect embayment ecosystem. The ability of fish and marine mammals to enter and leave the embayment would likely be substantially altered. The significance of operational impacts to fish, marine mammals, and saltwater wetland dependent birds and terrestrial species would likely be site-specific.

Environmental Justice

If significant impacts occurred in any resource areas as a result of the operations of hydrokinetic facilities, and these impacts disproportionately affected minority or low-income populations, then there could be an environmental justice impact. Issues of potential concern during operations are noise, ecological, and visual impacts. Additional impacts include limitations on access to the area for tribal activities.

Hazardous Materials and Waste Management

Hazardous material associated with the operation and maintenance of hydrokinetic energy devices and associated support components would include the fuel for boats, vessels, and barges, and lubricants and hydraulic fluids contained in the wave or tidal energy devices. Impacts from accidental spills, accidental fuel releases, and releases of solid debris are expected to be minor if appropriate management practices are followed. Garbage and sanitary waste generated onboard the vessels and barges would be returned to shore for disposal.

Industrial wastes are generated during routine maintenance (used fluids, cleaning agents, and solvents). These wastes typically would be put 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.

Adverse impacts could result if these wastes were not properly handled and were released to the environment. Given current standards the impact of this is expected to be minor.

Human Health and Safety

The primary hazard associated with operation and maintenance of hydrokinetic energy devices and associated components is the risk of drowning while working on or above water. The potential health and safety risks that could result in injuries and fatalities include onboard accidents; collisions between the vessel or barge and marine vessels; and natural events, such as hurricanes, earthquakes, tsunamis, and severe storms. Also, other marine vessels could collide with the wave energy devices. Deploying navigational aids such as lighting and foghorns would minimize vessel collisions with wave energy devices. All personnel involved with the operations and maintenance activities would utilize appropriate safety equipment and would be properly trained in required Occupational Safety and Health Administration (OSHA) practices.

Land Use

All types of hydrokinetic facilities would likely exclude traditional uses of the areas where they are constructed. Commercial shipping, fishing, and recreation uses may be the most likely uses that could be affected. Depending on the nature and visibility of the facilities, the visual impacts of hydrokinetic development might also create conflicts with existing shore-based uses.

Paleontological Resources

The operation and maintenance of offshore facilities would have no direct impacts on paleontological resources unless additional undisturbed areas are developed. Potential indirect impacts associated with the operation and maintenance of onshore facilities would be limited to unauthorized collection of fossils made possible by access roads if they make remote lands accessible to the public.

Socioeconomics

Direct impacts would include the creation of new jobs for operation and maintenance workers 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. However, the total number of operations and maintenance jobs likely would be small and therefore the associated socioeconomic impacts are anticipated to be minimal.

Soils and Geologic Resources

Seabed or riverbed disturbance would be minimal from maintenance activities and sediments are unlikely to be affected. Maintenance activities would also be unlikely to activate geological hazards. A wave energy farm could cause a reduction in wave height of 10-15%, and this reduction could result in an interruption of the natural sediment transport along the shore, increasing erosion downdrift. The impact is greater the closer the wave farm is to the shore, and is greater for floating devices oriented parallel to the shore. Tidal and river in-stream turbines will cause turbulence downstream that might cause scour of the seabed or riverbed if the units are located near the bottom.

During operation, the soil and geologic conditions would stabilize at onshore facilities. Soil erosion and soil compaction are both likely to continue to occur along access roads.

Transportation

No noticeable impacts to transportation are likely during operations. Maintenance vessels would service the hydrokinetic energy devices at regular intervals, but the additional level of activity resulting from this is anticipated to be small. Infrequent, but routine, truck shipments of component replacements to the dock during maintenance procedures are likely over the period of operation.

Visual Resources

Visual impacts of the operation of hydrokinetic energy devices would be the same as identified for construction activities, with the exception of the increase in vessel and vehicle traffic associated with construction.

Water Resources (Surface Water and Groundwater)

Water Use

Water use at the port would be required for normal operation, including fire protection, cleaning and maintenance of equipment, and consumptive use of personnel. Water would also be required for consumptive use on the vessels.

Water Quality

Vessels used for maintenance of hydrokinetic energy devices and components could contribute small amounts of fuel or oil to the ocean or river through bilge discharges or leaks. Damage to a hydrokinetic energy device, which may contain petroleum-based materials, could result in water contamination. Anchoring of the ships can cause sediment from the seabed to enter the water column. Onshore activities that could affect water quality are those that cause soil erosion, or discharges of waste or sanitary water. Negligible to minor impact to water quality would be expected.