When 104 million gallons of fuel start coursing through military pipelines this fall in a massive three-month defueling operation, anything could happen. Especially when it involves a World War II-era tank system, embedded in Red Hill, that sits just 100 feet above a major Oahu water source.

So it is critical for the operation to be meticulously planned and rehearsed before its October start, to prevent any spillage — and for government regulators to firmly ride herd every step of the way. Lax oversight of the Navy’s Red Hill tanks had occurred for far too long, unfortunately — until the disastrous November 2021 fuel spill that contaminated drinking water in the Hickam area.

That’s why Friday’s finalized consent order by the Environmental Protection Agency with the Navy and the Defense Logistics Agency (DLA) brings equal measures of skepticism and optimism that regulators will indeed hold the military to account on defueling and toward permanent closure of the 20-tank system. The EPA order is additional ballast to the state Department of Health’s existing emergency order over the Navy, which mandates state sign-off on every aspect of the Red Hill tank closure plan.

In fact, there was some reassurance when the DOH, in a May 3 letter, disapproved of the Navy’s then-plan, saying it fell short on details so did not satisfy requirements of its emergency order. That spurred the Navy last week to supplement its plan and make this welcome announcement: That after defueling, all three large fuel pipelines associated with the storage tanks would be removed, underscoring its commitment “to never use the tanks for storage of fuel or other hazardous substance storage.”

Removal of the three pipelines, the Navy said, also will eliminate long-term maintenance costs and provide “more flexibility for potential beneficial non-fuel reuse within the tunnel space.”

What that reuse and repurposing will entail remains an open debate — one that surely will be heated given the prevailing public mistrust of the military after its 2021 fuel spill that contaminated water to an area affecting some 93,000 people, sickening hundreds of them. And then a year later, the spewing of toxic firefighting foam with “forever chemicals” that leached into the Red Hill soil due to a contractor error.

All that emphasizes the DOH’s need to scrutinize the Navy’s self-proclaimed “closure in place” — and the myriad details on the method of permanent closure (remove, fill, or close in place) and associated design and process.

For now, the meticulous planning and drills for defueling advance, with third-party quality reviews throughout. It is imperative that things move apace, for safe and expeditious defueling to start Oct. 16 and be mostly done by Jan. 19; the last 100,000 to 400,000 gallons will require an end-phase process yet to be determined.

In tandem with the state DOH, the EPA must vigorously enforce its own consent-order terms of defueling for the Navy, such as:

>> Continued sampling of area residents, schools and businesses to safeguard drinking water quality.

>> Conducting tightness testing of each Red Hill fuel storage tank for potential of leaks and proactively correcting any defects. (Tank tightness testing began Monday and will run through July 21.)

Post-2021, community engagement on Red Hill has grown, as it should, and continued oversight will be crucial. In fact, it was due to public input on the EPA’s draft consent order that some laxness was rightly called out, resulting in tighter conditions.

One important example: Creation of a Community Representation Initiative, to meet monthly with EPA, Navy and DLA officials for updates and provide input into key decisions. Also, reporting requirements were added for the Navy and DLA to notify the Initiative of any spill that poses an emergency or immediate threat to health, and to require posting on Navy and DLA websites within 24 hours.

That last condition is especially resonant. Residents cannot, should not, forget how Navy leaders initially tried to hide the November 2021 fuel spill, and its real health dangers, from affected military families and everyone else. It will now be up to careful calculations and hard work, plus utmost vigilance, to prevent any such repeat.