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Tribal Energy and Environmental Information Clearinghouse: Environmental resources for tribal energy development
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Hydrokinetic Energy Facility Decommissioning/Site Reclamation Impacts

Decommissioning and site reclamation activities that may cause environmental impacts include hydrokinetic energy devices, underwater structures, and onshore facilities.

Typical offshore activities during the hydrokinetic energy facility decommissioning and site reclamation phase include hydrokinetic energy device removal, removal of anchoring structures, cutting pilings at an acceptable depth below the seabed or riverbed, removal of the dam at a barrage facility, and removal of transmission and signal cable. Some of the components may be abandoned in place rather than removed.

Onshore activities include removal of structures, breaking up of concrete pads and foundations, removal of access roads that are not maintained for other uses, recontouring the surface, and revegetation. Potential impacts from these activities are presented below, by the type of affected resource.

The following potential impacts may result from hydrokinetic energy facility decommissioning and site reclamation.

Acoustics (Noise)

Sources of noise during decommissioning would be similar to those during construction (with the exception of pile driving), and would include ships and barges and their associated equipment such as cranes and compressors. Onshore noise would result from removal of the facilities, and would be similar to construction noise.

Air Quality (Including Global Climate Change and Carbon Footprint)

Emissions from decommissioning activities offshore include emissions from ship engines and from diesel engines on cranes and generators and other demolition equipment on the ship or barge. Emissions from onshore activities result from diesel equipment, trucks and vehicles, and fugitive dust from structure removal, backfilling, dumping, and restoration of disturbed areas.

The length of time for removal of the hydrokinetic energy facility and onshore facilities would be less than for construction. Air quality impacts from decommissioning would be minor.

Cultural Resources

Decommissioning activities should have no additional impact on cultural resources unless new areas in addition to those affected by initial construction are disturbed. If cultural sites are present, theft of cultural artifacts could be a problem if access roads were left in place and the area was not adequately protected after facility removal was completed.

Visual impacts of the hydrokinetic energy facility would be mitigated if the offshore and onshore sites were suitably reclaimed. However, despite the physical removal of the development, the impact of landscape changes on an area considered sacred to Native Americans could remain.

Ecological Resources

Decommissioning activities would be similar to construction activities except for pile driving. Explosives might be used for removal of some structures below the ocean or river surface. Marine mammals, sea turtles, and fish close to the detonations could be injured or killed. Impacts to biological resources from decommissioning activities would be similar in nature to impacts from construction, but of a reduced magnitude.

If a barrage or wave or tidal energy farm becomes a significant hauling out area for seals and sea lions, their population might increase over the life of the facility. Removal of facilities in this case could result in a loss of these animals if the natural environment does not have the carrying capacity for these animals. Following site reclamation, the ecological resources both offshore and onshore could eventually return to conditions prior to installation of the hydrokinetic energy facility or barrage facility.

Environmental Justice

If significant impacts occurred in any resource area, and these impacts disproportionately affected minority or low-income populations, then there could be an environmental justice impact. Issues that could be of concern during decommissioning are noise, dust, and visual impacts from the project site, as well as possible restoration of fish and wildlife populations that could benefit subsistence users.

Hazardous Materials and Waste Management

Substantial amounts of solid and industrial waste would be generated during the decommissioning and dismantling of the hydrokinetic energy or the barrage facility. Much of the solid material (e.g., steel, turbines, transmission cable, pilings) could be recycled and sold as scrap. The remaining nonhazardous waste would be sent to permitted disposal facilities.

Industrial wastes (lubricating oils, hydraulic fluids, coolants, solvents, and cleaning agents) would be treated similarly to maintenance wastes during operation (transported to an off-site disposal facility). Impacts could result if these wastes were not properly handled and were released to the environment.

Human Health and Safety

Potential impacts to workers and public health and safety during the decommissioning of a hydrokinetic energy or barrage facility would be similar to those from construction of the facility. 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

Upon decommissioning, both offshore and onshore land use impacts resulting from construction and operation of a hydrokinetic energy or barrage facility would be largely reversed. No additional land use impacts would occur during this phase.

Paleontological Resources

Decommissioning activities should have no additional impact on paleontological resources unless new areas in addition to those affected by initial construction are disturbed. If paleontological sites are present, theft of these resources could become a problem if access roads were left in place and the area was not adequately protected after facility removal was completed.

Socioeconomics

Decommissioning activities for a hydrokinetic energy facility are similar to those during construction and would likely require a similar number of workers, but removal would be completed in less time than the original construction.

Because the workforce to operate these facilities is relatively small, impacts to the local and regional economies from the loss of these jobs after decommissioning would be minor. There would also be a loss of the tax base supported by the energy development.

Soils and Geologic Resources

Seabed and riverbed disturbance during decommissioning would result from removal of the pilings or anchors and mooring lines required for anchoring the wave energy devices and from excavation required to remove buried electrical and signal cable if they are not abandoned in place. Depending on the types of facilities present, some or all of the anchoring mechanisms could be abandoned in place to minimize disturbance of the bottom. Decommissioning activities would also be unlikely to activate geological hazards.

Onshore activities during the decommissioning phase that would impact soils and geologic resources include the removal of access and on-site roads, buildings, dams, and other structures; and vehicle traffic. Surface disturbance, heavy equipment traffic, and changes to surface runoff patterns could cause soil erosion. New impacts to geologic resources in addition to those caused during initial construction are not anticipated.

Transportation

Traffic at the port or river dock would increase as crews begin work dismantling both land and water based facilities and as hydrokinetic energy devices and components are removed and transported to recycling facilities or permitted disposal facilities. Boat and vessel activity would increase during the decommissioning phase. Short-term increases in the use of local roadways would occur during the decommissioning period.

Visual Resources

Viewers onshore and offshore would observe a short-term increase in vessel traffic transporting wave energy devices, transmission cable, salvage debris, and workers from the site to the port. The activities required to dismantle the components would also be noticed. These impacts would be negligible to minor for onshore viewers, and minor to moderate for boaters close to the activities.

Possible sources of visual impacts during removal of onshore facilities include ground disturbance and vegetation removal, and increased traffic. Increased truck and vessel traffic and human activity at the port facility would also be visible. These impacts would be negligible to moderate to viewers near the activity.

Water Resources (Surface Water and Groundwater)

Water Use

Water would be required for dust abatement during removal of onshore facilities and may need to be hauled in from off-site. The quantity of water used likely would be small. Water use at the port would be required for normal operation and water would also be required for consumptive use on the vessels.

Water Quality

Vessels used for transport and removal of hydrokinetic energy devices and components could contribute small amounts of fuel or oil to the ocean or river through bilge discharges or leaks. Anchoring of the ships and removal of anchoring devices and electric cables could cause sediment from the seabed or riverbed 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.