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Geologic Sequestration Operations Impacts

Environmental impacts that could occur while operating a geologic sequestration project would mostly result from long-term habitat change within the project site, waste management, noise the presence of workers, and potential spills.

Typical activities during the operations phase include operation of wells and compressor stations or pump stations, waste management, and maintenance and replacement of facility components. Impacts could also result from the fact that a geologic sequestration project could be linked to an enhanced oil recovery or enhanced coalbed methane recovery project, in which case the environmental impacts discussed in the Oil and Gas section would be relevant. The potential impacts resulting from a standalone geologic carbon sequestration project are presented below, by the type of affected resource.

Acoustics (Noise)

The main sources of noise during the operations phase would include compressor and pumping stations, producing wells (including occasional flaring), and vehicle traffic. Compressor stations produce noise levels between 64 and 86 dBA at the station to between 58 and 75 dBA at about 1 mile (1.6 kilometers) from the station. Use of remote telemetry equipment would reduce daily traffic and associated noise levels within the project area. The primary impacts from noise would be localized disturbance to wildlife, recreationists, and residents. Noise associated with cavitation is a major concern for landowners, livestock, and wildlife.

Air Quality

The primary emission sources during the operations phase would include compressor and pumping station operations, vehicle traffic, and operating wells. Venting of carbon dioxide may occur during injection and pipeline maintenance operations.

Cultural Resources

During the operations phase, impacts to cultural resources could occur primarily from unauthorized collection of artifacts and from visual impacts. In the latter case, the presence of the aboveground structures could impact cultural resources with an associated landscape component that contributes to their significance, such as a sacred landscape or historic trail. Damage to localities caused through off-highway vehicle (OHV) use could also occur. The potential for indirect impacts (e.g., vandalism and unauthorized collecting) would be greater during the operations phase compared to the drilling/construction phase, due to the longer duration of the operations phase.

Ecological Resources

During the operations phase, adverse impacts to ecological resources could result from:

  • Disturbance of wildlife from noise and human activity;
  • Exposure of biota to contaminants; and
  • Mortality of biota from colliding with aboveground facilities or vehicles.

Ecological resources may continue to be affected by the reduction in habitat quality associated with habitat fragmentation due to the presence of operating wells, pipelines, ancillary facilities, and access roads. In addition, the presence of access roads may increase human use of surrounding areas, which, in turn, could impact ecological resources in the surrounding areas through:

  • Introduction and spread of invasive nonnative vegetation,
  • Fragmentation of habitat,
  • Disturbance of biota,
  • Increase in hunting (including poaching), and
  • Increased potential for fire.

The presence of an injection well field could also interfere with migratory and other behaviors of some wildlife.

In some coal bed methane production areas, methane gas or carbon dioxide gas could seep up into fields and create dead zones. High levels of carbon dioxide could asphyxiate wildlife in their burrows.

Environmental Justice

Possible environmental justice impacts during the operations phase include the alteration of scenic quality in areas of traditional or cultural significance to minority populations. Noise and health and safety impacts are also potential sources of disproportionate effects to minority or low-income populations.

Hazardous Materials and Waste Management

Industrial wastes are generated during routine operations (lubricating oils, hydraulic fluids, coolants, solvents, and cleaning agents). These wastes are typically placed 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. Impacts could result if these wastes were not properly handled and were released to the environment. Environmental contamination could result from accidental spills of herbicides or other chemicals. Chemicals in open pits used to store wastes may pose a threat to wildlife and livestock.

Should geologic sequestration become common, a wide diversity of geologic formations are likely to be encountered. Depending upon the nature of the formation targeted for injection, it may be necessary to increase the injectivity of carbon dioxide by using hydraulic fracturing, an established production technique in the oil and gas industry discussed under the Oil and Gas Production Activities of this website. Hydraulic fracturing fluids can contain innocuous constituents, like sand and water, and potentially toxic substances, such as diesel fuel (which contains benzene, ethylbenzene, toluene, xylenes, naphthalene, and other chemicals), polycyclic aromatic hydrocarbons (PAHs), methanol, formaldehyde, ethylene glycol, glycol ethers, hydrochloric acid, and sodium hydroxide. Since some aspects of a hydraulic fracturing operation are considered proprietary, information about the specific constituents used in a given hydrofracturing operation may not be available, thus causing some concern over the risks presented by this practice. Some of the hydrofracture fluids used to increase the injectivity of a carbon dioxide injection well would probably be pumped out of the well and then be managed at the surface in tanks or impoundments. However, some of the fluids would remain in the underground formation. For example, in the process of producing hydrocarbons and produced water, about 20 to 40% of the fluids used for hydrofracturing may remain underground. Thus, should hydraulic fracturing be used in a carbon sequestration injection well, these fluids could have an impact on underground water sources that are close (horizontally or vertically) to the injection well.

During the operations phase, scale and sludge wastes can accumulate inside pipelines and storage vessels. They must be removed periodically from the equipment for disposal. These wastes may be transported to off-site disposal facilities. In some instances, they may be disposed of via landspreading, a practice that entails spreading the wastes over the surface of the disposal area and mixing it with the top few inches of soil.

Health and Safety

Possible impacts on health and safety while operating an injection field include accidental injury or death to workers and, to a lesser extent, the public (e.g., from an OHV collisions with project components or vehicle collisions with workers). Health impacts could result from water contamination, dust and other air emissions, noise, soil contamination, and stress (e.g., associated with living near an industrial zone). Potential fires and explosions would cause safety hazards. 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.

Land Use

Land use impacts during the operations phase would be an extension of those that occurred during the drilling/construction phase. However, to some extent, land can revert to its original uses after the major drilling/construction phase is over. For example, farmers can graze livestock or grow crops around the well sites. Other industrial projects would likely be excluded within the sequestration project area. Recreation activities (e.g., OHV use and hunting) are possible, although gun and archery restrictions would probably exist. Operations may conflict with livestock and farming operations.

Paleontological Resources

Impacts to paleontological resources during the operations phase would be limited primarily to unauthorized collection of fossils. This threat is present once the access roads are constructed, making remote areas more accessible to the public. Damage to localities caused by OHV use could also occur. The potential for indirect impacts (e.g., vandalism and unauthorized collecting) would be greater during the operations phase compared to the drilling/construction phase, due to its longer duration.


Direct socioeconomic impacts would include the creation of new jobs and the associated royalties and taxes paid for carbon emission avoidance created by the sequestration project. Indirect impacts are those impacts that would occur as a result of the new economic development and would include new jobs at businesses that support the expanded workforce or that provide project materials, and associated taxes. Potential impacts on the value of residential properties located adjacent to an oil or gas field would continue during this phase.

Soils and Geologic Resources

Following construction and drilling, disturbed portions of well and ancillary facility sites not required for operations would be revegetated. This would help to stabilize soil and geologic conditions. Routine impacts to soils during the operations phase would be limited largely to soil erosion impacts caused by vehicular traffic. Any excavations required for maintenance would cause impacts similar to those from the drilling/construction phase, but at a lesser spatial and temporal extent. The accidental spill of product or other wastes would likely cause soil contamination. Except in the case of a large spill, soil contamination would be localized and limited in extent and magnitude. In areas where interim reclamation is implemented (e.g., reclamation of an individual well that is no longer needed), ground cover by herbaceous species could re-establish within one to five years following seeding of native plant species and diligent weed control efforts, consequently reducing soil erosion. Operations might preclude or interfere with mineral development activities in the project area, including oil and gas development and mining activities. Possible geological hazards (earthquakes, landslides, and subsidence) could be activated by injection activities.


Impacts to transportation during the operations phase would be similar to those for the drilling/construction phase. However, unless carbon dioxide is transported to the site by truck or rail, daily traffic levels, particularly heavy truck traffic, would be expected to be lower during the operations phase compared to the drilling/construction phase. For the most part, heavy truck traffic would be limited to periodic visits to a well site for workovers, and formation treatment. The use of pipelines to convey carbon dioxide to the operating site would reduce the volume of traffic during the operations phase. If a pipeline is not used for the injection well field, multiple truckloads per day would be needed.

Visual Resources

Once operating facilities are installed, portions of well pads, access roads, and pipeline rights-of-way (ROWs) that are not needed for operations would be reclaimed; however, much of the disturbed area would continue to contrast with the natural form, line, color, and texture of the surrounding landscape. This would impact undisturbed vistas and areas of solitude. The aboveground portions of an injection well would be highly visible in rural or natural landscapes, many of which may have few other comparable structures. The artificial appearance of an injection well may have visually incongruous "industrial" associations for some, particularly in a predominantly natural landscape. Any nighttime lighting would be visible from long distances. During the operations phase, indirect impacts to visual resources would occur as a result of sequestration activities (e.g., industrial traffic, heavy equipment use, and dust). However, human activity would be substantially lower than during the drilling/construction phase.

Water Resources (Surface Water and Groundwater)

During the life of an injection well, the integrity of the well casing and cement will determine the potential for adverse impacts to groundwater. If subsurface formations are not sealed off by the well casing and cement, aquifers can be impacted by other nonpotable formation waters, hydraulic fracturing fluids, or the injected carbon dioxide.

Other potential impacts to water availability and quality during the operations phase would include possible minor degradation of water quality resulting from vehicular traffic and machinery operations during maintenance (e.g., erosion and sedimentation) or herbicide contamination resulting from improper application. A spill or blowout could potentially cause extensive contamination of surface waters or a shallow aquifer. Contaminated groundwater could potentially be discharged into springs or as base flow into stream channels, leading to surface water contamination.

Recovered waters used for hydraulic fracturing could cause altered surface water quality or an increase in flows in normally dry water bodies such as ephemeral drainages, if they are disposed of by discharge to the surface.