A gas company wants to expand a pipeline in the south—but it would sharply increase air pollution in North Carolina towns

Fast Company

30-05-2025

Two compressor stations along Transco's natural gas pipeline in North Carolina would emit more than 935,000 tons of planet-warming greenhouse gases each year, state records show. The expansion would also contaminate nearby communities with harmful air pollutants up to 350% over current levels.
Transco, a division of the Houston-based group Williams, plans to increase the horsepower at the existing compressor stations in Lexington, in Davidson County, and in Mooresville, in Iredell County. The stations would accommodate the company's Southeast Supply Enhancement Project (SSEP), a pipeline expansion that traverses five states: Virginia, North Carolina, South Carolina, Georgia, and Alabama.
Compressor stations use high pressure to force gas through a pipeline; they are located every 50 to 60 miles along a route. They routinely leak methane, a powerful greenhouse gas, and other pollutants through valves, flanges and other connectors. The gas is also sometimes intentionally released directly into the atmosphere, a practice called venting, and sometimes the gas is flared, or burned off, during maintenance, shutdowns and startups. Venting is worse for the climate, while flaring produces more harmful air pollution.
Each compressor station would be powered by natural gas, according to Transco's recent air permit applications to the N.C. Division of Air Quality. Division officials are reviewing the applications and will accept public comment after the evaluations are complete. Meanwhile, environmental advocates are asking local government officials to oppose Transco's entire natural gas expansion.
Transco did not respond to an email requesting comment on the air permit applications.
With increased horsepower comes increased pollution. At the Lexington station, concentrations of carbon monoxide, volatile organic compounds, sulfur dioxide and hazardous air pollutants, such as cancer-causing formaldehyde, would increase over current levels, by between 175% and 350%, state records show.
Residents in Lexington and Mooresville 'are already burdened by decades of air pollution from existing Transco infrastructure and deserve to breathe clean air,' said Juhi Modi, North Carolina field coordinator at Appalachian Voices. 'NCDEQ has the power to defend against Transco's proposal to emit more health-compromising pollution into our communities.'
EPA data show Davidson County is already afflicted by six types of air pollutants regulated under National Ambient Air Quality Standards.
Davidson County is in compliance with the air quality standards, according to state officials, but they apply to large areas, like a county, and 'aren't necessarily going to be reflective of the reality on the ground for the people who live around these compressor stations,' said Deirdre Dlugoleski, a former associate attorney with the Southern Environmental Law Center, now with Defenders of Wildlife. 'Compliance with the NAAQS isn't enough to ensure that environmental justice communities close to these sites won't be harmed.'
Neighborhoods within a mile radius of the Lexington compressor station rank among the highest in the state in terms of exposure to very fine particulate matter (known as PM 2.5), ozone, and toxic releases to the air, according to the EPA's EJ Screen. Nearly half of the 800 residents in the affected area are low-income.
The potential risks to public safety and the environment prompted the Midway Town Council, by a 4-1 vote, to formally oppose SSEP and the compressor station in Lexington, about 10 miles south of Midway.
Davidson County already has 176 miles of natural gas and liquid petroleum pipelines within its boundaries. Midway officials cited the 'negative impacts on air and water quality, residents' health and property values,' in their May 5 resolution, filed with the Federal Energy Regulatory Commission, or FERC.
Town officials asked FERC to consider a 'no-build option' and, in the event the pipeline is expanded, to require the compressor stations to use the best available control technology to reduce emissions.
At the Mooresville station, Transco's air permit application shows the increases would range from 20% to 37% over current emissions levels, depending on the pollutant.
Like their Lexington counterparts, people living within a mile of the station are exposed to some of the highest levels of PM 2.5, ozone, toxic air releases and diesel pollution. These neighborhoods also flank Interstate 77, one of the main arteries into Charlotte.
Both stations would emit toxic air pollutants acrolein, benzene, and formaldehyde at high rates. In Lexington, benzene exceeds federal hourly emission rates by 100 times; in Mooresville, the figure is 61 times.
These rates trigger a requirement for the company to conduct air dispersion modeling to measure contaminant levels, if they move off site and how far.
'This proposed massive methane gas project would add more pollution and health risks to North Carolina communities already struggling with poor air quality, compared to the rest of the state,' said Caroline Hansley, campaign organizing strategist at Sierra Club. 'NCDEQ must exercise its authority to protect North Carolinians and deny the permit for this unneeded, dirty, and dangerous project.'
More Demand From Data Centers
In North Carolina, the SSEP includes the Eden Loop, 4.4 miles in Rockingham County, where the pipeline enters the state from Virginia. The Salem Loop, also part of SSEP, is longer, running roughly 24 miles through Guilford, Forsyth, and Davidson counties.
The SSEP is one of three major pipeline projects in North Carolina. MVP Southgate is proposed for Rockingham County, where it would tie into the T-15, a pipeline which would run east to Duke Energy's new natural gas plants in Person County.
All of these projects are estimated to begin operating within the next three to five years, although they often run behind schedule because of permitting issues, litigation or construction delays. There is still a vacancy on the FERC commission, which could also cause backlogs.
Transco officials say the project is necessary to accommodate increased energy demand from data centers. Some energy analysts, like Tyler Norris of Duke University, though, counter that load flexibility could preclude the need for more generation and transmission.
Environmental advocates argue that energy companies are financially incentivized to build pipelines. From 2018 to 2023, Transco's average return on equity—earnings—was 17%, according to the National Gas Supply Association.
Earlier this spring, Transco updated its project filings with FERC, which reflected minor adjustments to the proposed route. Maps show hundreds of homes and businesses, schools, day cares, even parks and recreational centers within the pipeline's 1,114-foot 'high consequence area.' Also known as the blast zone, these areas are where the force of an explosion could kill or injure people, as well as damage or destroy property.
The zone is based on the diameter of the pipeline—SSEP is 42 inches—and its maximum allowable pressure. Within these areas, there are different classifications of risk, depending on population density and the number of vulnerable people who couldn't quickly evacuate.
Some homes lie as close as 20 feet from the center of the pipeline, according to Transco's filings with FERC. The pipeline skirts churches; the Oak Ridge Weekday School; a child care center in Guilford County; the VA Medical Center in Kernersville; and U.S. Highway 52, a major thoroughfare. It would burrow under three acres of Triad Park, a 6,000-acre recreational area that straddles Guilford and Forsyth counties.
Farther south in Davidson County, Wallburg Elementary School enrolls more than 720 students in pre-K through Grade 5. It is less than a quarter mile from the pipeline and within the blast zone, as is the Wallburg Recreational Center across the street.
In a recent presentation to Guilford County Commissioners, Transco officials emphasized that 'safety is the highest priority.' The company continuously monitors its pipelines and frequently inspects them, officials said, and uses pressure and temperature sensors to warn of potential problems.
Previous studies of pipeline accidents in Kentucky, Virginia, and New Mexico have shown that blast zones extend farther than originally calculated, according to the Pipeline Safety Trust, a nonprofit based in Washington state.
The trust raised safety concerns about the SSEP in its recent comments to FERC. The SSEP route already contains up to four other pipelines of different types, and FERC should calculate the blast to reflect those co-locations, wrote Erin Sutherland, the trust's policy and program director, and attorney. 'This is a serious environmental and public health danger that FERC should consider.'
Even routine construction will affect communities along the route. 'There's a huge gap that is going to fall on local municipalities,' Hansley said. 'People's wells could be blasted and impacted in Oak Ridge and other places. The roads could see massive traffic increases from heavy loads, get damaged and then who would end up paying for it?'