In late October, Navy officials began contacting media outlets ahead of announcing the results of an investigation into a May fuel leak at their Red Hill Underground Fuel Storage Facility, which has been the subject of contentious debates about the risk it poses to Oahu’s drinking water.

They wanted to make sure that one point, in particular, was emphasized: The fuel leak was due to a control room operator’s unfortunate failure to follow correct procedures. The leak, according to Navy officials, was not the result of larger issues at its aging tank farm.

“Had the control room operator followed the procedures outlined in the operations order, this situation would not have occurred,” Capt. Albert Hornyak, commanding officer at the Naval Supply Systems Command’s Fleet Logistics Center Pearl Harbor, told the Honolulu Star-Advertiser Oct. 26 as he discussed the results of the investigation into the May 6 leak of 1,618 gallons of jet fuel.

But what Navy officials didn’t tell the media, or state regulators, was that just weeks prior, on Sept. 29, they had detected another pressure surge in a pipeline similar to the one that caused the May fuel leak, and they were so concerned that they shut down Red Hill operations for nine days while they investigated.

In fact, Hornyak believed there could be multiple valves throughout Red Hill’s pipeline system that were leaking, according to an Oct. 3 email Hornyak sent to other top Navy officials, a copy of which was obtained by the Star-Advertiser this week.

A visual inspection of three pipelines leading into an underground pump house found a “sagging pressure condition,” which was similar to the conditions that led to the May 6 leak, according to Hornyak’s email.

“Red Hill operations will remain paused until the root cause creating the sagging conditions is determined,” Hornyak wrote, adding that his team was going “line by line” through data to check if the operation order for transfers was adhered to and if “additional out of balance situations have occurred.”

“Additionally, based on the May 6th event as well as this most recent event, I believe there are multiple valves in the Red Hill pipeline system (that) are potentially leaking,” Hornyak said in the email.

The Navy, in response to questions about the email, said the temporary shutdown of Red Hill was “representative of the abundance of caution used in the professional management of complex fuel operations at Red Hill.”

“No fuel was released, no damage occurred, there was no impact to fuel delivery, and operations resumed after taking a pause to assess a surge in the system,” said Mike Andrews, a spokesman for Navy Region Hawaii, by email. He said Red Hill operations were paused from Sept. 30 until Oct. 8.

Navy officials did not respond to specific questions about why the pressure surge and shutdown of Red Hill weren’t publicly disclosed, or whether they alerted the state Department of Health, which regulates the facility, that they were concerned there might be multiple pipeline valves that are leaking.

A spokeswoman for DOH said on Tuesday that the department was not aware of the Sept. 29 pipeline surge or operations being suspended at Red Hill, but declined to comment further.

The revelation about the temporary shutdown of Red Hill and concerns about the pipeline system come at a sensitive time for the Navy, which is trying to persuade DOH to issue it a five-year permit to continue operating its tank farm.

The Hawaii Sierra Club and Honolulu Board of Water Supply are engaged in a contested case hearing over the permit and have raised concerns for years that the massive tank farm can’t be operated safely. The facility includes 20 underground tanks, each capable of holding 12.5 million gallons of fuel, that sit just 100 feet above an aquifer that serves as a major source of drinking water for Oahu. They’ve urged the Navy to install major safeguards, such as a tank-within-a-tank system, or move the tanks altogether.

The Navy also is under pressure from Hawaii’s congressional delegation, which last week called on the U.S. Department of Defense’s Inspector General to launch an independent investigation into whether the Navy “covered up evidence or intentionally delayed” notifying state regulators earlier this year about a separate leak of fuel into Pearl Harbor.

In a letter to acting Inspector General Sean O’Donnell, the delegation said the investigation was needed to “restore the community’s trust in how the Navy operates Red Hill.”

On Tuesday, U.S. Sen. Mazie Hirono told the Star-Advertiser that the Navy had not informed her of the shutdown at Red Hill. She said she was “frustrated having to learn about incidents at Red Hill from sources other than the Navy.”

“This is yet another example of why the delegation is requesting both a meeting with the Secretary of the Navy and an IG investigation,” Hirono said in an emailed statement. “We need the facts about what is happening at Red Hill, and I expect to swiftly hear from the Navy about this matter.”

The Navy said the Sept. 29 pressure surge in its F-24 pipeline was detected during a routine transfer of fuel from Red Hill’s tank No. 4 to Hickam Airfield storage tanks. Operations were paused while inspectors examined the F-24 pipeline, tanks and valves.

Andrews said an investigation found that the surge was the result of a “vacuum created by thermal contraction due to normal temperature variations,” and that operation orders that equalize pressure in the pipeline have since been refined.

“This is the type of analysis and modification to procedures that ensure safe operations of the Red Hill facility,” he said.

Andrews said that pausing operations at Red Hill in response to such an event is routine, but he didn’t respond to a question about whether such a shutdown had occurred in the past.

According to David Kimo Frankel, an attorney for the Hawaii Sierra Club, pausing Red Hill operations for more than a week “is not a routine event.”

“If normal temperature variations are causing vacuums and surges that is not comforting at all,” Frankel said.

He said the situation raised multiple concerns, including a lack of transparency on the part of the Navy.

“This is troubling because it suggests there may be multiple leaks,” Frankel said, adding that the pressure conditions raise concerns that a pipeline-related explosion could ignite a fire in the fuel facility.