Honolulu City Council members appear ready to weigh in on the future of the Red Hill fuel tank storage facility despite the Navy’s continued reservations about what the measure says.

Resolution 18-266 urges the federal Environment Protection Agency and the state Department of Health to reject allowing the Navy to upgrade the existing single-wall lining of 18 massive fuel tanks under Red Hill as its response to concerns raised about the tanks’ integrity in the wake of the 2014 leak of 27,000 gallons of fuel from one of the tanks.

The Council Public Infrastructure, Technology and Sustainability Committee, after hearing more than an hour of testimony Tuesday, is expected to vote to support the resolution today.

Critics, including officials with the Honolulu Board of Water Supply and Sierra Club of Hawaii, said the Navy’s plan fails to ensure that the World War II-era tanks, which hold up to 12.5 million gallons of fuel each, do not pose a safety risk to a major aquifer that supplies drinking water which sits 100 feet below.

On Monday, BWS Water Manager Ernest Lau stressed to committee members that the fuel is contained within each of the tanks by a quarter-inch steel liner. To illustrate his point, Lau showed committee members a 1-foot-square, quarter-inch-thick square prop with photos of the interior of a real tank, showing corrosion, pasted against one side.

“A quarter-inch is not a very thick piece of metal that’s been there for, now, 74 to 75 years,” he said. “This steel plate is holding 12-1/2 million gallons of fuel from leaking out into the environment.”

He added, “Right now the current process of repairing the tanks is to scan from the inside to see where there’s a problem with the quarter-­inch steel thinning because of corrosion and put a patch in time before it penetrates through.”

Lau said his agency would prefer a secondary containment option or a double­-lined tank. If that’s not possible, the tanks should be relocated away from the aquifer, he said.

He noted that the recent Navy study analyzed 10 square feet out of the steel lining in one tank, out of about 70,000 square feet per tank, a sample size he called inadequate.

Navy officials said the Department of Defense is spending hundreds of millions of dollars to comply with regulations and to improve and modernize the Red Hill facility while the resolution calls for actions that would cost billions. They also said the resolution is based on published reports about the corrosion rate of the tanks that are inaccurate.

Capt. Marc Delao, commanding officer of Naval Facilities Engineering Command, Hawaii, and regional engineer of Navy Region Hawaii, said secondary containment would present engineering challenges.

“The way these tanks were built, it was not remove the top of the mountain and dig and build; it was sort of burrow in and lock the infrastructure in,” Delao said.

Mark Manfredi, Navy Region Hawaii’s Red Hill program director, defended the scanning process that sampled only 10 steel liner plate samples for verification purposes. He likened the situation to a car in a repair shop. “You wouldn’t cut it all off and decide only a small percentage of it needs to be repaired, because then you’d have a car that was all cut up,” he said.

Likewise, “you don’t want to deliberately go in and cut them up only to find that a vast majority, 98 percent of the tank’s surface, doesn’t warrant any repair,” he said. “If we were to assess the condition of the tank, then absolutely it would require a far greater sample size to get a statistically appropriate number of samples to do that.”

Manfredi said it’s unfair to take one of the samples, see that it has rust and conclude a tank is in bad shape. “You don’t know what the depth of the corrosion is,” he said.

As for the minimum thickness of the tanks’ steel liner, there is no standard for underground tanks, Manfredi said. As a result, the standard for repairs the Navy uses is double the thickness of what the American Petroleum Institute uses for above-ground tanks, he said.

The Navy recently submitted the results of testing that provided raw data which, according to a Navy statement released Monday, “validates the accuracy of earlier electromagnetic and ultrasonic scans we did to see the condition of a tank liner and determine areas in need of repair.”