Hydrokinetic Energy Facility Construction Impacts

Construction activities that may cause environmental impacts include seabed and riverbed pile driving, drilling, excavation, blasting, trenching, and ship and vehicular traffic.

Typical activities during the wave or tidal turbine energy farm construction phase include assembling hydrokinetic units on shore; transporting each device to its designated location offshore; anchoring it to the seabed; connecting each device electrically to a central junction box; laying or burying submarine transmission and signal cable; and construction of onshore substation and electrical transmission lines to connect to the grid. Activities required for river in-stream facilities are essentially the same but are conducted in a river rather than offshore.

For a barrage facility, a dam would be constructed across the inlet or estuary to contain the incoming tidal flow and a powerhouse would be constructed to produce hydroelectric energy. Onshore activities include ground clearing, grading, excavation, vehicular traffic, and construction of facilities. Potential impacts from these activities are presented below, by the type of affected resource.

The following potential impacts may result from hydrokinetic energy facility construction activities.

Acoustics (Noise)

Underwater and above-water noise sources include boat, ship and barge activity associated with transporting workers, materials, and hydrokinetic energy devices to the offshore site, installing hydrokinetic facilities, and the laying of electrical and signal cables. Human receptors on the ocean shore likely would be far enough away for any impacts to be minor. Human receptors on the river shore could be close to the activities required for locating and anchoring river in-stream turbines.

If pile driving is required for anchoring hydrokinetic energy devices or for construction of offshore power-gathering stations, the noise could be audible at the shoreline and might be annoying to populations. This impact would be intermittent. Techniques for laying cable could require use of air guns, rock cutters, or shaped explosive charges. The noise could be intense but would occur over a very short time period.

Onshore noise would result from pre-assembly of the hydrokinetic energy devices and the construction of onshore facilities. The primary source of noise during construction of onshore facilities, transmission lines, and a barrage facility would be from equipment operation (e.g., rollers, bulldozers, diesel engines). Other sources of noise include vehicular traffic, tree felling, and blasting.

Whether the noise levels from these activities exceed U.S. Environmental Protection Agency (EPA) guidelines or local ordinances would depend on the distance to the nearest residence and the effectiveness of any mitigating measures to reduce noise levels. If near a residential area, noise levels from blasting and some equipment operation could exceed the EPA guideline but would be intermittent and extend for only a limited time.

Adverse impacts due to noise could occur if the site is located near a sensitive area, such as a park, wilderness, or other protected area. The primary impacts from noise would be localized disturbances to wildlife, recreationists, and residents.

Air Quality (Including Global Climate Change and Carbon Footprint)

Offshore activities that generate emissions include ship, boat, and barge traffic to and from the hydrokinetic energy facility site, installation of the hydrokinetic energy devices and their associated anchoring devices, and the laying of the underwater cables. Air emissions result from the operation of ship engines and on-ship equipment such as cranes, generators, and air compressors. In most cases, an air quality permit would not be required for offshore facility construction. However, in areas of non-attainment for any criteria pollutants, the states have authority to regulate near-shore activities.

Emissions generated during the construction phase of land-based facilities, (including docks, equipment storage, and assembly area) include:

• Vehicle emissions;
• Diesel emissions from large construction equipment and generators;
• Volatile organic compound (VOC) releases from storage and transfer of vehicle/equipment fuels;
• Small amounts of carbon monoxide, nitrogen oxides, and particulates from blasting activities; and
• Fugitive dust from many sources, such as disturbing and moving soils (clearing, grading, excavating, trenching, backfilling, dumping, and truck and equipment traffic), mixing concrete, use of un-vegetated soil piles, drilling, and pile driving.

These emissions would also be expected during construction of a barrage facility. A permit may be required from the state or local air agency to control or mitigate these emissions, especially in non-attainment areas.

Cultural Resources

For offshore projects, trenching, dredging, and placement of hydrokinetic energy devices and associated components could impact shipwrecks or buried archaeological artifacts. For onshore projects, impacts to cultural resources could occur from site preparation (e.g., clearing, excavation, and grading) and construction of transmission-related facilities. For either offshore or onshore projects, visual impacts could also result from disruption of a historical setting that is important to the integrity of a historic structure, such as a lighthouse.

Potential cultural resource impacts include:

• Complete destruction of the resource if present in areas undergoing surface disturbance or excavation;
• Unauthorized removal of artifacts or vandalism to cultural resource sites resulting from increases in human access to previously inaccessible areas; and
• Visual impacts resulting from vegetation clearing, increases in dust, and the presence of large-scale equipment, machinery, and vehicles (if the affected cultural resources have an associated landscape or other visual component that contributes to their significance, such as a sacred landscape or historic trail).

Ecological Resources

Wave and Tidal Turbine Energy Farms

The potential effects of construction activities associated with the placement of wave and tidal turbine energy devices on marine mammals, sea turtles, and fish may include behavioral responses such as avoidance and deflections in travel direction. Noise and vibrations generated during the various activities could disturb the normal behaviors and mask sounds from others members of the same species or from predators. Coastal birds could be displaced from offshore feeding habitats; however, most birds would be likely to return within relatively short periods following cessation of construction activities. A few could be injured or killed by collisions with the survey vessels.

The movement and deposition of sediment during construction activities on the seafloor could kill benthic organisms, a source of food for fish. Effects to fish could potentially occur if spawning or nursery grounds are disturbed during construction or if re-suspended sediments cause smothering of habitat. The area of seafloor disturbance from anchoring systems relative to the surface area occupied would be small.

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

Onshore impacts from construction could affect terrestrial vegetation and wildlife, but the overall impact is anticipated to be minimal because permanent on-shore facilities are expected to be small. Wildlife would be most affected by habitat reduction within the project site, access roads, and transmission line rights-of-way. Wildlife within surrounding habitats might also be affected if the construction activity (and associated noise) disturbs normal behaviors, such as feeding and reproduction. Impacts to wildlife are expected to be minor.

Turtles nest along the south Atlantic and Gulf coastlines. Those nests containing eggs and emerging hatchlings could be affected by construction activities onshore. Lighting from the construction areas could disorient the hatchlings and increase their exposure to predators. The minimal amount of onsite construction would limit the impact to no more than a few nests.

River In-stream Facilities

The potential effects of the placement of river in-stream energy devices and associated construction on fish may include behavioral responses such as avoidance and deflections in travel direction. Noise and vibrations generated during the various construction activities, especially placement of supporting structures and installation of submarine transmission lines, could disturb the normal behavior. Those displaced because of avoidance behaviors during construction are likely to return within relatively short periods following cessation of construction activities.

The movement and deposition of sediment during construction activities on the riverbed could kill benthic organisms, a source of food for fish. Effects to fish could potentially occur if spawning or nursery grounds are disturbed during construction or if re-suspended sediments cause smothering of habitat. The area of riverbed disturbance would be very small relative to the availability of similar habitat in surrounding areas.

Terrestrial wildlife would be most affected by habitat reduction within the project site, access roads, and transmission line rights-of-way. Wildlife within surrounding habitats might also be affected if the construction activity (and associated noise) disturbs normal behaviors, such as feeding and reproduction. 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.

Underwater habitat would be altered and marine species could be injured or killed during construction of the intake and dam. The ability of fish and marine mammals to enter and leave the embayment would be substantially altered. The significance of construction impacts to fish, marine mammals, and saltwater wetland dependent birds and terrestrial species is likely to be site-specific.

Terrestrial wildlife also would be affected by habitat reduction caused by construction of land-based facilities within the project site, including access roads and transmission line rights-of-way. Wildlife within surrounding habitats might also be affected if the construction activity (and associated noise) disturbs normal behaviors, such as feeding and reproduction.

Environmental Justice

If significant impacts occurred in any resource areas, and these impacts disproportionately affected minority or low-income populations, then there could be an environmental justice impact. Issues of potential concern during construction are noise, dust, and visual impacts from the construction site and possible impacts associated with the construction of new access roads.

Additional impacts could include limitations on access to the area for tribal recreation, subsistence, and traditional activities. Environmental justice impacts are dependent upon vulnerable populations being located within the area of influence of a project and are, therefore, site-specific.

Hazardous Materials and Waste Management

Hazardous material associated with installation of hydrokinetic energy devices and construction of associated support components would include fuels, lubricants, and hydraulic fluids contained in the hydrokinetic energy devices or used in ships and construction equipment. 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.

Solid and industrial waste would be generated during onshore construction activities. The solid wastes would likely be nonhazardous and consist mostly of containers, packaging materials, and wastes from equipment assembly and construction crews. Industrial wastes would include minor amounts of fuels, spent vehicle and equipment fluids (lubricating oils, hydraulic fluids, battery electrolytes, glycol coolants), and spent solvents.

These materials would be transported off-site for disposal, but impacts could result if the wastes were not properly handled, and were released to the environment. No impacts are expected from proper handling of all wastes.

Human Health and Safety

The primary hazard associated with hydrokinetic energy device installation and construction of 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.

Potential onshore impacts to workers would be similar to those expected for any construction project with earthmoving, large equipment, and construction and installation of industrial facilities. Most accidents in the construction industry result from overexertion, falls, or being struck by equipment. Construction-related illnesses could also result from exposure to chemical substances from spills.

In addition, health and safety issues include working in potential weather extremes, and possible contact with natural hazards, such as uneven terrain and dangerous plants, animals, or insects. All personnel involved with the construction would utilize appropriate safety equipment and would be properly trained in required Occupational Safety and Health Administration (OSHA) practices.

Land Use

The wave and tidal turbine energy farm could occupy from 17 to 250 acres of ocean surface. The facility would exclude commercial shipping and, possibly, fishing activity. A river in-stream facility could occupy about 5 acres and could affect commercial shipping, recreation, and fishing activities. A barrage facility would impact the area behind the dam and would exclude commercial and recreational ships and boats from entering the previously accessible estuary unless a ship lock were constructed.

Existing onshore land use during construction would be affected by intrusive impacts such as ground clearing, increased traffic, noise, dust, and human activity, as well as by changes in the visual landscape. In particular, these impacts could affect those seeking recreational opportunities on the shore or in the water. Generally, offshore and onshore impacts associated with these types of facilities are expected to be minor.

Paleontological Resources

For offshore projects, trenching, dredging, and placement of hydrokinetic energy devices and associated components could impact paleontological resources. For onshore projects, impacts to paleontological resources could occur directly from the construction activities and increased accessibility to fossil locations. Potential impacts include:

• Complete destruction of the resource if present in areas undergoing surface disturbance or excavation; and
• Unauthorized removal of paleontological resources or vandalism to the site as a result of increased human access to previously inaccessible areas, if significant paleontological resources are present.

Socioeconomics

Direct impacts would include the creation of new jobs for construction workers and the associated income and taxes generated by the hydrokinetic energy facilities. Indirect impacts would occur as a result of the new economic development, and would include new jobs at businesses that support the expanded workforce or provide project materials, and associated income and taxes. An influx of new workers could strain the existing community infrastructure and social services; however, since most hydrokinetic projects are relatively small, the workforce required is also expected to be relatively small and impacts, therefore, are expected to be minor.

Soils and Geologic Resources

Seabed and riverbed disturbance would result from drilling or pile driving required for anchoring the hydrokinetic energy devices and from excavation required to bury electrical cable. The area disturbed is a small portion of the area occupied by the hydrokinetic energy facility. Construction activities would also be unlikely to activate geological hazards.

Surface disturbance, heavy equipment traffic, and changes to surface runoff patterns during construction of onshore facilities could cause soil erosion. Impacts of soil erosion could include soil nutrient loss and reduced water quality in nearby surface water bodies.

Transportation

Traffic at the port would increase as wave or tidal energy devices and components are delivered prior to assembly transport to the project site. Vessel traffic will increase during the construction phase.

The same effect would occur with river in-stream projects although, because they are generally much smaller installations, the impacts to transportation would be less significant. Short-term increases in the use of local roadways would occur during the onshore construction period.

Barrage projects would be relatively large projects and would likely require more labor for construction. This would cause an increase in traffic on local roads and potentially could disrupt local traffic use.

Visual Resources

Viewers onshore and offshore would observe an increase in vessel traffic transporting hydrokinetic energy devices, components, and workers to the site. The activity during installation would also be noticed. Wave, tidal, and in-river facilities are generally low-profile structures, and although visible, may not be as objectionable as larger, more visible structures.

The overall effect on visual resources is also related to existing uses (especially land-based residential uses) that would have a view of the hydrokinetic energy farm areas and will require site-specific assessment. Construction of the dam at a barrage site would change the character of the water basin and could create visual concerns for nearby residents or recreation users.

Possible sources of visual impacts during construction of onshore facilities include ground disturbance, construction of highly visible facilities, vegetation removal, road construction, and increased traffic. Increased truck and vessel traffic and human activity at the port facility supporting project construction would also be visible, although it is anticipated this would only be a short-term impact.

Water Resources (Surface Water and Groundwater)

Water Use

Water would be used onshore for dust control when clearing vegetation and grading and for road traffic; for making concrete; and for domestic use by the construction crew. Water would likely be trucked in from off-site. The quantity of water required likely would be small.

Water Quality

Vessels used for transport and installation of hydrokinetic energy devices and components could contribute small amounts of fuel or oil to the ocean through bilge discharges or leaks. Anchoring of construction ships, and installation of anchoring devices and electric cables, can cause sediment from the seabed to enter the water column. Onshore activities that cause soil erosion or discharges of waste or sanitary water could affect water quality. Negligible to minor impact to water quality would be expected.