Friday, March 30, 2001

Story and photos by Wayne Specht, Misawa bureau chief

Environmentalists at Misawa Air Base are tracking underground residual fuel believed leftover following a fuel tank explosion 46 years ago not far from this underground fuel tank used to store aviation fuel today.

MISAWA AIR BASE, Japan — Air Force environmental officials say underground residual jet fuel from a massive tank explosion 46 years ago is posing no health risks to off-base residents.

A plume of the dissolved fuel has moved 200 feet beyond the base’s fence line onto Misawa Airport property, Stars and Stripes learned last week from a base environmental protection committee meeting report.

But off-base residents are in no danger, said Greg Gangnuss, chief of the 35th Civil Engineering’s environmental flight.

"We do not believe there is any risk at all with this release that has been there for (almost) 50 years," Gangnuss said. "It’s an isolated petroleum release."

Base officials have been keeping Misawa City and Japanese government officials informed of the situation they believed occurred Feb. 21, 1955.

Stars and Stripes reported in its Feb. 23, 1955, edition that a 420,000-gallon fuel tank exploded that day, killing a Japanese foreman. An archived copy of the former base newspaper, the Wingspread, said the worker was taking tank measurements at the time of the blast.

No reason was given for the explosion that caused $84,000 in damages.

The Air Force discovered the fuel leakage in 1997, Gangnuss said, after a small plume of unrelated fuel was detected the year before in a monitoring well. The base decided to do soil borings throughout the tank farm located east of the base’s Falcon Gate.

"The ’96 discovery led us to do test borings throughout the tank farm in 1997 ... that’s when the problem on the east side of the tank farm was revealed," he said.

The Air Force has spent $1 million so far in determining the extent of the problem, Gangnuss said.

"We believe we’re looking at the tail end of that explosion, and a problem relatively small in size," he said.

Gangnuss said soil borings showed that components consisting of benzene, toluene, ethylene and xylene were present in the soil and in groundwater about 25 to 30 feet below the surface.

"It’s relatively old and weathered petroleum, and the components suggest the fuel is gasoline, which was used as aviation fuel in the ’50s," Gangnuss added.

Aviation fuel is stored in underground tanks like this one at Misawa Air Base, Japan, where base environmentalists are tracking a plume of residual fuel from a tank explosion 46 years ago.

Tests have shown that in the years since the explosion, the fuel has moved underground in two ways: on top of the groundwater at a level of about 25 feet, and as a plume of dissolved fuel, which was detected about 200 feet east of the tank farm on airport property, he said.

Fuel in the dissolved stage, Gangnuss explained, means naturally occurring bacteria in the groundwater is breaking down fuel components.

Groundwater in the vicinity of the tank farm, Gangnuss said, does not come in contact with people. A natural barrier separates the fuel from an aquifer from which the city draws drinking water located immediately east of the airport.

Gangnuss also said he believes the plume has stopped moving, and may even be regressing.

Misawa’s 35th Fighter Wing commander, Brig. Gen. Chip Utterback, met with Misawa Mayor Shigeyoshi Suzuki last October to inform him of the situation.

A city spokesman said Suzuki was out of town and unavailable for comment until Friday.

Air Force officials also have kept Japanese government agencies in the loop about the situation as well as the U.S. Embassy in Tokyo.

"We were told last year that the spillage is minor," said Tadanori Meguro, deputy chief of Misawa’s Defense Facilities Administration Office, which deals with U.S.-Japan defense issues. "Japan will not make financial contributions to study the problem."

Meguro added that the city routinely checks the quality of water taken from wells near the airport.

"So far, no trouble has been reported," he said.

Gangnuss said feasibility and pilot studies are planned, which could lead to removal of the free-source fuel by siphoning, instead of dirt removal.

"This is a problem we’ve inherited from our grandfathers," Gangnuss said. "It’s been in the ground a long time."

Hiroshi Chida contributed to this report.

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