As military brass comes to grips with the fallout of the recent contamination of the Navy’s Oahu water supply that serves 93,000 people, Navy divers have been working day and night in the Red Hill water shaft gathering samples and trying to extract petroleum from the water.

Mobile Diving and Salvage Unit One has been on the scene for over a week. The divers said it’s been a slow process, but they’re finally beginning to make headway. They’ve reached the stage where they’re now “skimming” the water system — removing contaminants that have floated to the top. On a video feed the divers monitor a white filmy substance that is visible on the water’s surface.

“It’s the beginning stages, we’ll have to see where the Navy’s gonna go next. But at least we’re assessing how well we can start skimming,” said Chief Warrant Officer Jose Castilla, commander of Mobile Diving and Salvage Company 1-8.

There are 17 divers with the company working in the well along with master divers from other units that have joined the effort. The Oahu-based team trains to work with shipwrecks and do underwater maintenance on ships and submarines in ports.

They’re an experienced team. Several of them recently worked on the USS Bonhomme Richard, a San Diego-based amphibious assault ship that was destroyed last year by a disgruntled sailor-turned arsonist in a fire that did $3.8 billion in damage. The Navy decommissioned the Bonhomme Richard in April and sold it for scrap.

“There’s a lot of unique circumstances to this job, but most of what we do is outside of the norm,” said salvage officer Lt. Cmdr. Chris Wilkins. “Working with damaged ships, sometimes pumping out subway tunnels, tearing up ships that have landed on reefs, we do all that kind of work so we’re always working outside of the norm. But this is definitely a new one for us.”

The subterranean Red Hill facility poses unique challenges for operations. The 20-tank facility can hold 230 million gallons of fuel and sits above a critical aquifer for the island. Though the divers train to work in hazardous and sometimes claustrophobic settings, the facility is like nothing else the divers have ever worked on. To enter the water system, they first have to first climb down an 80-foot ladder through a 24-inch manhole.

“Nothing worked really well right off the bat, but we were able to make smattered minor changes in the way we put things together,” said Castilla.

When the operation began they had to wear specialized dry suits that protected them from any contamination in the water. But the suits are incredibly heavy and working in the confined, dark spaces put them at risk of overheating — or hyperthermia.

“It’s dark and really hot,” said Petty Officer 2nd Class Reed Akey, a four-year Navy veteran from Mobile, Ala.

During one of the first exploratory operations, one of the divers became short of breath and was overheating and had to be withdrawn, forcing the team to reassess its operations. They subsequently ensured that the divers spent as little time in the dry suits as needed when they were above the tunnel and got out of them as soon as possible when they exited.

“It was not like a medical emergency,” Castilla said, but the divers recognized the situation was dangerous and needed to be handled with care.

Even above ground the air is relatively thin and hot. In the control room, the rest of the team monitors operations and watches a video feed and manages supplies along with engineering specialists. Much of the equipment they initially brought wasn’t designed to operate in this environment. Akey said that has been the most challenging part.

“The logistics, getting all the gear down here (was) basically trial and error really,” Akey said. “Stuff would work, stuff wouldn’t work, having to go back to bring different equipment. See if that would work.”

The Navy now says it believes that a Nov. 20 spill of 14,000 gallons of a jet fuel and water mixture from the facility’s fire suppression system caused the contamination. Castilla said his team is making progress, but he’s cautious in assessing how much contamination remains.

“It’s hard to say, because this is actually just the sub area right here. There’s a 100-foot tunnel that collects the water from the porous rock and the lava tubes and all that kind of runs a little tangent to this,” he said. “So the engineers are working to calculate based on what we thought might be the thickness of contamination versus the surface area.”

It’s been a long haul for the divers. They work in shifts going down the hatch. Several members of the team live in areas affected by the contamination and have had to live in hotels, working their shifts at Red Hill and going back to Waikiki to catch some sleep before driving back to do it all over again.

But for now the divers are no longer going directly into the water and using less gear and are working from a slippery catwalk in the well. But while they’re no longer wearing the heavy dry suits, they continue to wear masks and breathing systems because they’re not sure how contaminated the shaft still is. But they do know it’s still hot, dark and cramped.

The process of skimming the system involves filling several 20,000-gallon tanks that will be hauled out by trucks. As of Sunday evening the response team had almost filled the first tank.

“There will be some sampling done to see how efficiently we’re getting enough contaminations for the volume of water that we’re actually pumping,” said Castilla. “If we skim too low, we might just keep getting water and not removing enough contamination.”

Wilkins said that setting up the system required a great deal of improvising.

“What we’re doing right here requires a lot of hydraulic power. We have to overcome roughly 115-foot vertical head. We’ve also got nearly 1,000 foot of discharge hose going out,” Wilkins said. “Our systems in the tunnel were limited by space and weight while we can move in here, so there’s been a lot of creative engineering getting this rigged up so we can get where we are today.”

As the divers work below ground, above ground the political firestorm over the Red Hill facility is growing amid growing calls to cease operations at the facility. On Sunday, Kaʻohewai, a newly formed coalition of Native Hawaiian organizations dedicated to shutting down the facility, held a rally calling for its closure.

On Friday, top officers with the Pacific Fleet told lawmakers it was their goal to end the crisis by Christmas. But the divers continuing to work in the facility aren’t offering any timelines.

“I don’t have a time frame,” said Castilla. “We’re here until we’re relieved, as with most Navy operations.”