Transmission Decommissioning/Site Reclamation Phase Impacts
Decommissioning and site reclamation activities that may cause environmental impacts include removal of aboveground project components, land recontouring, and revegetation.
Transmission facilities are removed after their useful life in a process called decommissioning. Following decommissioning, the right-of-way (ROW) may be restored to resemble its original condition or reclaimed to some standard that results in stable environmental conditions. Typical activities during the decommissioning and site reclamation phase include removal of aboveground components and gravel from access roads and other ancillary facility sites, breaking up of concrete pads and foundations, recontouring the ground surface, and revegetation. Potential impacts from these activities are presented below, by the type of affected resource.
The following potential impacts may result from decommissioning and site reclamation of an energy transmission project.
Sources of noise during decommissioning would be similar to those during construction and would be caused primarily by construction equipment and vehicular traffic. Whether the noise levels exceed U.S. Environmental Protection Agency (EPA) guidelines or local ordinances would depend on the distance to the nearest residence. Near residential areas, noise levels could exceed EPA guidelines but would be intermittent and extend for only a limited time.
Emissions generated by activities during the decommissioning and reclamation phase include vehicle emissions; diesel emissions from large construction equipment and generators; and fugitive dust from many sources such as structure removal, backfilling, dumping, reclamation of disturbed areas (grading, seeding, planting), and truck and equipment traffic.
Decommissioning activities would have little potential to impact cultural resources because these resources may have been removed professionally prior to construction, or may have been already disturbed or destroyed by prior activities. The collection of artifacts could continue to be a problem if access roads are left in place or if the restored ROW still affords remote access. Visual impacts of the energy transmission project would be mitigated if the site were restored to its preconstruction state. However, despite the physical removal of the project, the impact of a scarred environment on an area considered sacred to Native Americans would likely remain.
Impacts to ecological resources from decommissioning and reclamation activities would be similar in nature to the impacts that occur during construction, but of a reduced magnitude. There would be a temporary increase in noise and visual disturbance associated with the removal of project facilities and site reclamation. Negligible to no reduction in wildlife habitat would be expected, and injury and mortality rates of vegetation and wildlife would be much lower than they would be during construction. Removal of aboveground structures would eliminate the impacts to wildlife that occur during operation (e.g., bird collisions with transmission lines and habitat fragmentation). Following site restoration, the ecological resources at the project site could eventually return to preproject conditions depending on the end use selected for the ROW.
If significant impacts were to occur in any of the resource areas and these were to disproportionately affect minority or low-income populations, then there could be an environmental justice impact. Issues that could be of concern during decommissioning and site reclamation are noise, dust, and visual impacts, as well as possible restoration of fish and wildlife populations for subsistence users.
Hazardous Materials and Waste Management
Substantial amounts of solid and industrial waste would be generated during the decommissioning and dismantling of the energy transmission project. Much of the solid material could be recycled and sold as scrap or used for other projects; the remaining nonhazardous waste would be sent to permitted disposal facilities. Industrial wastes (oils, hydraulic fluids, coolants, solvents, and cleaning agents) would be treated similarly to maintenance wastes during operation (put in containers, characterized, and labeled, possibly stored briefly, and transported by a licensed hauler to an appropriate permitted 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 worker and public health and safety during decommissioning and site reclamation would be similar to those during construction; and relate to earthmoving, use of large equipment, dismantling of industrial components, and transportation of overweight and oversized materials.
Upon decommissioning, land use impacts resulting from construction and operation of an energy transmission project could be largely reversed depending on the end use selected for the ROW. No permanent land use impacts would occur during this phase.
Decommissioning activities have little potential to impact paleontological resources because these resources would have been removed professionally prior to construction, or would have been already disturbed or destroyed by prior activities. Fossil collection could continue to be a problem if access roads are left in place or if the restored ROW still affords remote access.
Direct impacts would include the creation of new jobs for workers during decommissioning and site reclamation activities 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. No adverse effect to property values is anticipated as a result of decommissioning. Site reclamation could result in values of residential properties that were adjacent to the ROW becoming equivalent to similarly developed residential areas that were not affected by the energy transmission project.
Soils and Geologic Resources
Activities during decommissioning that would result in impacts to soils include removal of access roads, substations, buildings, aboveground and portions of belowground pipelines, transmission line components, and other ancillary structures. Surface disturbance, heavy equipment traffic, and changes to surface runoff patterns could cause soil erosion. Soil erosion impacts include soil nutrient loss and reduced water quality in nearby surface water bodies. Upon completion of decommissioning, disturbed areas would be contoured and revegetated, which would minimize the potential for soil erosion. Impacts to geologic resources would not be expected.
Short-term increases in the use of local roadways would occur during decommissioning and site reclamation. Overweight and oversized loads could cause temporary disruptions to local traffic.
During decommissioning, impacts on visual resources would be similar to those encountered during construction. These impacts are related to road redevelopment, temporary fencing of the work site, intermittent or phased activity persisting over extended periods of time, removal of portions of buried structures, and the presence of idle or dismantled equipment, if allowed to remain on site. Restoring a decommissioned site to preproject conditions would entail recontouring, grading, scarifying, seeding and planting, and perhaps, stabilizing disturbed surfaces. Newly disturbed soils would create a visual contrast that would persist at least several seasons before revegetation would begin to disguise past activity. Restoration to preproject conditions may take much longer. Invasive nonnative plant species may colonize newly and recently reclaimed areas. Nonnative plants could produce contrasts of color, form, texture, and line.
Water would be used for dust control for road traffic, dismantling of towers, pipelines, substations, and other buildings, and for consumptive use by the construction crew. It might be trucked in from off-site or obtained from local groundwater wells or nearby surface water bodies, depending on availability.
Water quality could be affected by activities that cause soil erosion, weathering of newly exposed soils causing leaching and oxidation that can release chemicals into the water, discharges of waste or sanitary water, spills of residual product remaining in the pipeline, and herbicide application or spills. Upon completion of decommissioning, disturbed areas would be contoured and revegetated to minimize the potential for soil erosion and water quality-related impacts.
Surface and groundwater flow could be affected by withdrawals made for water use, wastewater and stormwater discharges, and the diversion of surface water flow for access road reclamation or stormwater control systems. The interaction between surface water and groundwater could also be affected if the two resources are hydrologically connected, potentially resulting in unwanted dewatering or recharging of any of these water resources.