Santa Clarita / Antelope Valley : 200th Toxic Waste Tank Is Unearthed at Base : Environment: Most of the 512 receptacles at Edwards date from WWII. Military is ahead of schedule.

The 200th underground storage tank was removed from the ground here Wednesday as part of a program to eliminate the potentially hazardous tanks, officials said.

“We are through the hardest part,” said Don Cowen, project manager for the Underground Storage Tanks program. “We have got the dirtiest tanks out.”

The Air Force is two years ahead of schedule in complying with state safety regulations requiring the removal of abandoned tanks and the replacement of underground tanks still in use with new double-layered tanks, Cowen said. The deadline for compliance is December, 1998.

There are no known blueprints locating the 512 tanks--most of which were put there during World War II--so officials used infrared scanners, radar detection and information from longtime military personnel to search out the tanks, Cowen said.

So far, the tank removal program has cost $3.1 million. The remaining cleanup will cost another $2.9 million, Cowen said.

At the base, workers in orange jumpsuits carefully measured the oxygen levels within the tank to ensure that there were no vapors that could cause an explosion before lifting the 12,000-gallon diesel fuel tank out of the ground with a crane.

“These can be very explosive things, if not handled right,” Cowen said.

The program has had a perfect safety record thus far, Cowen said. Officials began removing the oldest tanks and those with possible contamination first.

It takes three days to remove one tank, Cowen said. Before each tank is removed, any remaining contents are extracted and the inside of the tank is triple rinsed with a special formula, he said.

The tank is then inspected for possible corrosion from the acid, solvents or gasoline it contained. If holes are found in the tank, the ground is evaluated for possible contamination and cleaned up. If no holes or contamination are found, the tank is loaded onto a truck and recycled or buried at a landfill, Cowen said.

The 200th tank was installed in 1958 and was used to fuel trackers and trailers on the base.

Cowen said most tanks have a life span of 25 years and “the age of most of the tanks is the prime reason why we are moving so rapidly.”

Cowen said Edwards has the largest inventory of tanks in the Air Force. The first tank was pulled from the ground in 1990.

Although most do not contaminate the ground, several underground tanks which contained heavy crude oil in the South Base of Edwards leaked the hazardous material at least 50 feet into the ground. Environmental officials said the hard clay ground kept the contaminants from seeping into the ground water 400 feet underground.

Regulatory agencies such as the state Environmental Protection Agency have worked in conjunction with the Air Force, overseeing the cleanup of the underground tanks.

The Air Force expects to keep at least 10 underground tanks in operation on the base.

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