A Navy report reveals multiple leaks of many thousands of gallons of fuel over 65 years from 20 giant underground military storage tanks completed in secrecy near Pearl Harbor during World War II, including up to 27,000 gallons of JP-8 aviation fuel in a release that was announced in mid-January.

The total spillage is not detailed, with spotty records from the once-classified facility providing a far from complete picture of the extent of the fuel loss — and its environmental consequences.

The track record of spills is mentioned in a 2008 Navy groundwater protection plan for the Red Hill Bulk Fuel Storage Facility. Recently obtained by the Honolulu Star-Advertiser, the report sheds new light on repeated spills and concerns about the long-term integrity of the fuel farm, and discusses the possible migration of some of that fuel into Pearl Harbor’s drinking water.

The Navy report notes dozens of leaks dating back to 1949, including the loss of 11,000 gallons in July of that year and 18,000 gallons in December in Tank 16.

From 1970 to 1972 there was an "unexplained" fuel drop of 31,294 gallons in Tank 1, and from 1975 to 1978 a similarly unexplained loss of 32,765 gallons.

Tank 15 "leaked badly upon refilling after tank repair and lining, no details," the report said of a 1981 fuel loss.

The report states that in some cases, the leaks went into internal tank piping known as "tell-tales" and were not external leaks. In other cases, there’s no indication where the fuel went.

In 1981, Tank 10 experienced a "severe leak" near the top of the tank and an unstated quantity of fuel ran out onto concrete, the report states.

Tom Clements, a spokes-man for Navy Region Hawaii, said in an email Friday that Tank 5, which experienced the most recent leak, had been drained of JP-8 by Jan. 18.

After a venting process that can take several weeks, workers will be able to enter the 245-foot-tall, 100-foot diameter steel-lined tank to investigate the source of the leak, Clements said.

"There is no indication at this time that the fuel has migrated beyond the concrete casing," Clements added.

Steven Chang, chief of the state Health Department’s Solid and Hazardous Waste Branch, said the Navy had just brought the tank back into service in December and when it was filled up it started to leak, eventually losing up to 27,000 gallons.

The 2008 Navy report notes steps that have been taken to improve monitoring for leaks. But it also raises concern about the age of the facility and the increased potential for a fuel leak breaching the steel liner and concrete containment and contaminating a nearby Navy well that provides 24 percent of the potable water to a Pearl Harbor water system serving 52,200 military consumers.

"The age of the facility and the mission-critical requirements for its storage capacity combine to present a significant future risk of a moderate to large release of fuel to the underlying groundwater," the report states.

While the tank steel liners have been repaired, the document says, the concrete containment casing cannot be maintained.

The water resource is "virtually irreplaceable," and remediation of a large fuel release and water contamination would be extremely costly and technically difficult, the report said.

Clements said the Navy "has continually refined its detection, protection and response capabilities at Red Hill over the years," adding, "We conduct routine, systemic checks of fuel levels in the tanks."

The Navy "routinely" conducts sampling and analysis of groundwater using wells dug beneath the tanks and soil vapor testing beneath the tanks, Clements said.

"We continue to improve our system of monitoring and detection and incorporate new technologies whenever possible," he said.

To prevent leaks, Clements said the tanks undergo a preventive maintenance cycle in which they are inspected to identify areas of weakness such as thinning of steel due to corrosion or weld deficiencies.

He added that once an inspection is complete, repairs are made and a tank is then in a "like-new" condition. Each tank undergoes a tank "tightness" test every two years to determine if there is any fuel movement.

Fuel levels are tracked daily and if a discrepancy is identified, it is researched to determine if a leak has occurred — which is how the recent Tank 5 leak was spotted, Clements said.

Each of the Red Hill tanks can hold 12.5 million gallons of fuel. The two rows of vertical tanks were built underground in secrecy and activated in 1943 to support World War II efforts in the Pacific. The upper domes of the tanks lie 100 to 200 feet below the existing ground surface.

A 2.5-mile tunnel — in which a mining train operates — runs to Pearl Harbor and carries pipelines that fuel the fleet. To this day, some people don’t know a train operates beneath their homes.

The Red Hill facility was considered an engineering marvel when it was completed, and today is deemed "critical" by the Navy to its mission in the Pacific.

At about the same time the fuel facility became operational, U.S. Navy well 2254-01 was dug about 3,000 feet downhill from the fuel farm, and includes a water tunnel, known as an infiltration gallery, extending across the water table to within 1,560 feet of the facility, the Navy report said.

The well pumps 4.4 million gallons of water per day to the Pearl Harbor water system.

The Board of Water Supply Halawa Shaft is about 5,000 feet northwest of Red Hill, providing water to hundreds of thousands of people on Oahu. In addition, the Moanalua wells are 6,700 feet from the fuel farm.

In groundwater modeling, an extended jet fuel spill reaching within 1,099 feet of the Navy water tunnel resulted in benzene levels greater than federal maximum contaminant levels, the Navy report said.

A release as small as 16,000 gallons near Tanks 1 or 2 (those closest to the water tunnel) could result in those conditions.

The 2008 Navy report said tanks 1, 6, 15, 16 and 19 were out of service at the time. A 2013 Navy letter said 15 tanks were in service. The Navy did not indicate how many are still in service and said only that at any given time, three are in the preventive maintenance cycle.

The tanks as of 2008 contained JP-5 and JP-8 jet fuel and F-76 diesel.

The Navy report said past inadvertent releases contaminated the fractured basalt, basal groundwater and soil vapor beneath the Red Hill facility with petroleum hydrocarbons.

However, Clements said, "To our knowledge, and for at least the past 40 years, the Navy has never had to shut down a drinking water well due to suspected or confirmed petroleum contamination."

The state Health Department put out a release Wednesday saying "very low" levels of lead were detected in the Pearl Harbor water system. Similarly low hydrocarbons were found in past records in the Red Hill water source.

Both were below state "action levels" and do not pose a health threat, the state agency said. An official said all of the findings may be from past fuel releases and not the recent spill.

Still, the past Red Hill spills, the most recent one, and potential for future fuel leaks are very much a concern, said the Health Department’s Chang.

"We are very concerned because the Navy’s (water tunnel) is downgradient from the facility," he said.

The picture relating to past leaks is murky, he added.

"We’ve seen documentation from the Navy, but it’s unclear," Chang said. "Over the period of time from like the 1950s I’d say up to 1984, something like that, they were able to get some sense of the condition of the tanks and based on that information, they estimate that there might have been releases from the tanks."

But "it’s not really quantified, exactly," he added.

The Navy report said because of the previously classified status of Red Hill, independent spill investigations were not conducted before 1995.

Groundwater sampling in 2005 at three wells in the facility and at two others, including the Navy well, showed diesel hydrocarbons exceeding state action levels at all the wells except the Navy well.

An Aug. 6, 2013, Navy letter notes diesel, 1-methylnaphthalene and naphtha- lene exceeding state action levels in groundwater wells beneath Red Hill.

Chang said groundwater wells beneath Red Hill can have petroleum levels of concern, while the farther Navy well does not, because many millions of gallons of water move very slowly through rock, or even remain semi-stationary, and biological action can help break down the fuel.

"Trying to track the movement (of fuel) through rock is rather difficult. It’s a challenge," he said.

Chang said his understanding is that neither JP-5 nor JP-8 has lead.

"It’s very possible the stuff we’re picking up (in the Pearl Harbor water) is actually from older (fuel) releases," he said.

Environmental activist Carroll Cox, who obtained the Navy reports, said he will ask for a state legislative hearing into the fuel spills.

"I believe the Navy and the (Health Department) must immediately convene a public meeting to apprise the public of the history of the facility and its numerous leaks," Cox said. "In my opinion, this situation has the potential to become a human health and ecological nightmare, if it hasn’t already."