Excavation of contaminated soils around a backup generator that leaked up to 700 gallons of diesel fuel at the summit of Haleakala is anticipated to begin soon, once the plan is approved by the state, military officials said Wednesday.

U.S. Secretary of the Air Force Frank Kendall paid a visit to Maui to check out the site, saying during a news conference Wednesday afternoon that the spill is “very regrettable and very embarrassing.”

Still, he is optimistic about “fully remediating” the land.

“Since that time, our response and notifications have moved with determined speed. We want to do this right,” Kendall said at the summit. “This incident hurts the environment, it harmed our reputation, calls into question the trust placed on us by our local communities. To be clear, I apologize for what has happened, and this department will put our full sustained effort into repairing what has been done.”

Earlier this month, Brig. Gen. Anthony Mastalir, the commander of the U.S. Space Forces Indo-Pacific, said that a power surge amid a lightning storm was the likely cause of a mechanical issue that allowed an estimated 700 gallons of diesel fuel to spill from the generator’s fuel tank into the soil at the summit of Haleakala.

A float in the generator’s main fuel tank was damaged by the surge on the night of Jan. 29, Mastalir had said. The mechanism usually sits on the surface of the fuel to signal the transfer pump to stop before it overflows, but it failed, allowing hundreds of gallons of fuel to seep down onto the sides of the concrete pad and into the ground. Its alarm also failed.

The generator at the Maui Space Surveillance Complex serves as the backup source of power if commercial power supplied by Hawaiian Electric goes out.

While on island, Kendall met and consulted with Maui County Mayor Richard Bissen Jr. and his staff to discuss how to respond, proceed with remediation and interact with the community.

The first pieces to the plan to remediate 200 cubic yards around the generator, a depth of about 6 feet, include excavating the soil around the cement pad.

No other plans were shared Wednesday.

Excavation will begin once the work plan is approved by all federal, state, county and local stakeholders, including the Department of Health, the U.S. Environmental Protection Agency, the U.S. Fish and Wildlife Service, the University of Hawaii Institute for Astronomy, the State Historic Preservation Division and the Department of Land and Natural Resources’ Office of Conservation and Coastal Lands.

The military anticipated approval of the work plan by DOH by Wednesday or today.

“At that point, we are ready to begin excavation,” Mastalir said.

Honolulu-based company Tunista Services is contracted to do the work.

On Tuesday, contractors used ground-penetrating radar and other equipment to identify and map utility pipes and wires at the summit in preparation for excavation work. They also took topographical measurements to ensure all soil and areas are returned to their natural state.

Meanwhile, the transfer pump in the generator continues to be operated manually while engineers and electricians study the malfunction; Hawaiian Electric has fixed the lighting protection devices that are on the site; and Space Force officials have inspected all six of their generators across the state to ensure that they are working properly.

“We’ve already compiled important lessons regarding the generator site, which are being shared across the Department of the Air Force to prevent future incidents like this from occurring,” Kendall said.

The Space Force said that on Feb. 14, it finalized a contract with CKM Cultural Resources to provide a cultural adviser and to monitor the remediation project, according to a news release. The adviser, Dane Uluwehiokalani Maxwell, was born and raised on Maui and is the grandson of Charles Kauluwehi Maxwell Sr., a Native Hawaiian leader and cultural expert who was critical of the early telescopes. Mastalir expected Dane Maxwell to be as vigilant as his grandfather.

“He’s been an integral part of what we’re trying to accomplish — full remediation with a cultural sensitivity of this location,” Mastalir said.

The military has also met with several community members, lineal descendants and 60 student leaders at Kamehameha Schools Maui to better understand the cultural significance of the land, rebuild trust and answer questions, he added.

Mastalir said that the telescopes atop Haleakala are constantly tracking and monitoring “activity in the space domain, protecting our nation’s most critical assets.”

“It is the mission that greatly contributes to the defense of the Pacific region and it is one of which Hawaiians can be proud,” he said.

Updates will be shared as authorities enter the next phase of remediation.

“When it comes to the cleanup of this sacred land, the best way to move fast is to slow down and to make sure you do the job right,” he said.

* Dakota Grossman can be reached at dgrossman@mauinews.com.