RICHMOND — A panel of federal judges has thrown out the permit for a natural gas pumping station in the historic African American community of Union Hill in Buckingham County, saying state regulators failed to consider whether the facility would disproportionately affect a vulnerable population.

The ruling is another setback for the Atlantic Coast Pipeline, a controversial 600-mile, $7.5 billion project being led by Dominion Energy.

Issued Tuesday by the U.S. Court of Appeals for the 4th Circuit, the decision faulted Virginia’s Air Pollution Control Board for an action that it said was “arbitrary, capricious, and unsupported by substantial evidence in the record.”

The panel — Chief Judge Roger L. Gregory, Judge Stephanie D. Thacker and Judge James A. Wynn Jr. — said the board glossed over concerns that the project was unduly harmful to a minority community.

“Environmental justice is not merely a box to be checked,” the judges wrote, “and the Board’s failure to consider the disproportionate impact on those closest to the Compressor Station resulted in a flawed analysis.”

The judges also ruled that the state failed to consider whether electric turbines would have been cleaner than the proposed gas-fired turbines.

Dominion can reapply for the air permit, but the state would have to evaluate that application based on the expectations laid out in Tuesday’s ruling.

“Our clients felt like Dominion was trying to erase their community out of existence,” said Greg Buppert, a lawyer for the Southern Environmental Law Center who worked on the case. “Whether or not a compressor station is in fact suitable for this site, I think, is an open question — and a significant risk for Dominion if they push forward here.”

A Dominion spokesman said the utility remains committed to building the project in Union Hill.

“We will immediately begin working with the state to resolve the procedural issues identified by the Court and are confident this can be completed in a timely manner,” spokesman Aaron Ruby said via email. “We expect the project will still deliver significant volumes to customers under our existing timeline, even as we work to resolve this permit.”

The Atlantic Coast Pipeline originates in gas fields in West Virginia and is set to cross the heart of Virginia, terminating in North Carolina. Construction has been suspended since December 2018 because of several federal court rulings that revoked permits.

In perhaps the most serious threat to the project, federal judges ruled that the U.S. Forest Service lacked authority to allow the pipeline to tunnel under the Appalachian Trail in Virginia. Dominion appealed that case to the U.S. Supreme Court, which is set to hear arguments late next month.

The pipeline has drawn passionate opponents along its length. But none have been more persistent or outspoken than those around Union Hill, a community settled by free blacks and former enslaved people around the time of the Civil War.

Members of two black Baptist churches formed an unlikely alliance with the residents of Yogaville, a nearby ashram, to oppose the project.

Together, they have won national attention; last year, former vice president Al Gore and civil rights leader William Barber toured the site and called on Gov. Ralph Northam (D) to step in to stop the project.

Dominion, meanwhile, hired a former state secretary of agriculture whose family is from Union Hill to spread goodwill in the community, offering a $5 million package of incentives including a community center and ambulances. But Dominion also asserted that the population around the proposed site was not heavily African American, using broad census data in its analysis.

Lakshmi Fjord, an adjunct professor at the University of Virginia, countered that claim with a door-to-door survey showing the vast majority of the residents closest to the site are black.

The Air Pollution Control Board, a panel appointed by the governor, ultimately made no determination about the racial makeup of Union Hill. At least two of the four members said at the final permit hearing that they were persuaded it was an environmental justice issue but believed emissions from the project would be so low it was a moot point.

The court’s ruling Tuesday said that conclusion was not adequate. Even if the compressor station is exemplary, the judges wrote, “what matters is whether the Board has performed its statutory duty to determine whether this facility is suitable for this site, in light of [environmental justice] and potential health risks for the people of Union Hill. It has not.”