Emptying underground Navy fuel storage tanks at Red Hill crossed a midway point Wednesday, and several state lawmakers received a briefing from military officials Thursday about the job and future cleanup work.

Complex and dangerous work to drain 104 million gallons of fuel at the Red Hill Bulk Fuel Storage Facility on Oahu began Oct. 16, and a first phase getting out 98% of the fuel is on pace to be finished Nov. 18.

On Wednesday the amount of fuel drained via gravity through the Navy’s improved pipeline system under intense safety measures reached 54.2 million gallons, and then topped 57 million gallons Thursday, said Joint Task Force Red Hill commander Vice Adm. John Wade during the briefing.

Wade led the nearly two-hour briefing for nine members of two Senate committees: Health and Human Services, and Agriculture and Environment.

Kathleen Ho, deputy director of environmental health at the state Department of Health, told the senators that the department is satisfied with the defueling work to date on the system, which sits just 100 feet above an aquifer supplying drinking water to most of Honolulu.

“We think they are doing a great job,” she said. “There haven’t been any notable incidents, so that is a good thing.”

DOH is monitoring defueling work together with the U.S. Environmental Protection Agency.

Ho also endorsed comments by some senators during the briefing about remediation work to Hono­lulu’s freshwater system needing to be part of the long-term job by the Department of Defense.

In November 2021 jet fuel from the facility tainted the Navy’s water system, which served 93,000 people, including military families and civilians in former military housing areas.

As a precaution, the Hono­lulu Board of Water Supply shut its Halawa shaft, which draws water from the aquifer below Red Hill and typically supplied neighborhoods stretching from Moanalua to Hawaii Kai. The Water Board also has been doing exploratory well drilling work and other things in response to the Red Hill disaster that is adding to costs facing ratepayers.

The military admitted that the aging World War II-era facility, as well as the pipelines that connect it to Joint Base Pearl Harbor-­Hickam, had fallen into disrepair and required extensive fixes and upgrades to safely remove the fuel without risking further spills or threats to water supplies.

In March 2022 the Pentagon committed to the tanks being drained and permanently closing the facility.

The task force spent the past year getting the system into proper shape for defueling, and most of the removed fuel is being shipped out of Hawaii for military use.

At Thursday’s briefing some senators pressed Wade for a commitment for the military to pay for state and county costs related to impacts on the aquifer. Wade said that is a Department of Defense policy decision beyond his mission, though he promised to relay the issue up the chain of command.

Environmental remediation work is expected to last “many, many years” after three to five years of facility closure work that the Navy is slated to begin after defueling by the task force is complete, according to Capt. James Sullivan, commanding officer of Naval Facilities Engineering Systems Command Pacific.

Defueling work by the task force headed by Wade is expected to last until the end of March because of several time-consuming steps to get residual fuel out of the system, which includes 10 miles of piping.

After the first phase draining 102 million gallons of fuel from the storage tanks, an additional roughly 140,000 gallons at the bottom of all the tanks needs to be drained Dec. 4-15 through 4-inch-diameter pipes.

Then, Wade said, work to get most fuel out of the pipeline, close to 440,000 gallons using gravity, should take from Jan. 15 to 19. After that the task force anticipates having to remove 60,000 gallons of fuel from over 180 low points in the pipeline through drains and valves from Jan. 22 to March 31.

Yet another 4,000 gallons likely will remain in sag points that developed throughout the pipeline over time, and this will be part of the Navy’s closure work.

“There are pockets of fuel that can’t be accessed through low-point drains,” Wade told senators at the briefing. “In order to access that fuel, you physically have to destroy the pipeline.”

Capt. Ted Carlson, chief of staff for Navy Region Hawaii, told the lawmakers that a Navy facility closure team will learn from the task force work to inform the closure job where just cleaning the 20 underground tanks is expected to take three years.

“This is not a simple hand over the keys — you had it, we have it,” he said. “No. We’re going to learn from their success and continue that on.”

The Navy’s closure work also is expected to involve removal of an estimated 28,000 gallons of sludge from the bottom of 14 tanks, fuel from soil and other hazardous materials possibly including asbestos, lead and more.

“Just like defueling, this is an extremely complex, multifaceted operation to close this facility, and it will take some time to do it right,” Carlson said.

The estimated closure work timetable is three to five years, not including environmental remediation.

“Suffice it to say that the Department of Defense is absolutely committed to get every drop of fuel and every toxic material that is in the facility,” Wade said. “Again, defueling — the removal of 104 million gallons — is the start to set the conditions for the long-term closure process, which will take several years.”

What ultimately becomes of the tanks accessed by tunnels has not yet been determined, and is a subject to be discussed by Congress.

Carlson told lawmakers that ideas floated include sealing the tanks empty, filling them with sand, using them for storage and even as part of a brewery.

“I think anything is on the table,” he said.