As the military continues to deal with the contamination of the Navy’s water system on Oahu, it’s now hauling in massive industrial-strength filters to extract water from the system, conducting large-scale flushing beginning this morning.

On Sunday afternoon an Air Force C-17 from Travis Air Force Base, Calif., transported a granulated activated carbon filtration system with two massive 10,000-gallon tanks that Navy officials said are capable of together processing roughly 1 million gallons of water per day. The Navy has contracted for 25 of the GAC devices under a $6 million emergency contract. Sunday’s delivery was added to seven devices already on the island.

“There are multiple types of GAC systems that we’re employing for a few different purposes,” said Lt. Cmdr. John Daly, a engineering officer who has been working on the Navy’s response.

Daly said that at the Navy’s Red Hill shaft, “water has to be pumped, and it will be processed through a separate array of GAC filters that are going to be set up nearby.” Others will be hauled to and from affected housing areas on trailers to extract water from fire hydrants to run through the filters.

Daly said that once the contaminated water has been filtered through the GACs, they will discharge it in a variety of locations, potentially including grassy fields and storm drains through permits with the state and federal government. The Navy insists this will be safe. “If there’s a wide grassy area, we can do a land discharge through a diffuser. So, essentially, (watering) the grass,” said Daly. “We’re discharging nontoxic effluent once it’s been filtered.”

Officials with the Navy’s Pacific Fleet now say they think that a Nov. 20 spill of JP-5 jet fuel from the Red Hill Bulk Fuel Storage Facility caused the contamination of the Navy water system that serves 93,000 people, mostly military families but also some local schools and businesses.

The Navy said it will begin this morning to flush water lines at the Pearl City Peninsula military housing neighborhood, connecting the GACs to fire hydrants and discharging the filtered water to storm drains.

“Pearl City Peninsula will be flushed first to serve as the safe test case given its proximity to the Waiawa well, which has been the source of the Navy’s drinking water since securing the Red Hill and Halawa wells on Nov. 28 and Dec. 3, respectively,” the Navy said in a news release.

Flushing of the distribution system at Pearl City Peninsula is expected to take one day.

Navy authorities had earlier in the crisis initiated flushing out hydrants as a means to clear water mains, but on Dec. 11 the state Department of Health issued the Navy a cease-and-desist order. The Health Department said the Navy wasn’t following state guidance, and had received complaints that the Navy wasn’t properly cordoning off areas.

In response the Navy ordered the GACs.

The Navy is also working with various teams of experts drawn from around the country, including a team from Purdue University in Indiana.

“We’re able to reach out to folks from all over industry and academia, kind of offer our best lessons and best technologies for how do we address the concerns of the community as we were trying to water the environment to clean the contaminants out of our system,” said Daly.

The Honolulu Board of Water supply was concerned that flushing creates a false sense of security, and argued that because petroleum does not dissolve in water, the pipe system could be permanently contaminated with fuel.

Gov. David Ige has also issued the Navy an order to defuel the tanks at the Red Hill facility until it can prove they’re safe — which top Navy officials said they will fight.

Other groups are calling for the permanent closure of the fuel storage facility, which sits atop one of Oahu’s aquifers.

Daly acknowledged concerns but said the experts he’s working with are confident the new delivered devices, along with other techniques, will clean the system.

“We’ve got some experience to lean on that demonstrates that this can be done through flushing,” said Daly, citing outside experts the Navy is consulting. “I understand that there’s concerns, and that’s why it’s not up to us,” he said, and added that the Navy’s efforts would be “full and open, transparent, and we’re showing that our methods work.”

On Friday officials with the Navy, Army, state Department of Health and U.S. Environmental Protection Agency signed a plan to restore clean drinking water to the contaminated water distribution system. Media were invited to watch them sign the document but were not allowed to read it, and the document still has not been released to the public.

The Navy closed off its Red Hill shaft Nov. 28 after military families began complaining of water that smelled like chemicals, with some saying they had been experiencing strange illnesses a week prior.

It has affected Army, Air Force and Navy housing areas that rely on the Navy’s water system. Col. Jason Terry, commander of the Air Force’s 515th Air Mobility Operations Wing, watched as airmen unloaded the GACs. “I live here on Hickam. My house is just over here. My family is one of the families that’s on the Navy water system,” said Terry.

In addition to bringing in the GAC systems, the Navy has had salvage divers working in the Red Hill well gathering samples and trying to remove contaminants. Some of the divers have themselves been displaced by the water crisis along with their families and are commuting to and from the facility from hotels in Waikiki.

Pacific Fleet leaders told members of the state Legislature on Dec. 10 that their goal was to have the water clean and families moving back into their homes by Christmas. Army officials earlier that day told residents that they saw a six- to eight-week timeline at best. Daly acknowledged that both the cleanup and reforms to follow will take time.

“We know this is a cleanup that we have to perform over time,” said Daly. “We understand that you know trust is hard to earn, and it is not given back easily.”