Ben Baker huddled inside his van, studying the instruments that told him a computer was recording the temperature of the sea of diesel fuel beneath him.

The afternoon was bitterly cold. Small signs beside the gasoline and diesel pumps cautioned that the Premium Oil station, 7020 S. Redwood Road, was closed for testing. On the station's windows were painted stars and the American flag, along with the slogan, GOD BLESS OUR TROOPS."This is a calibration test," Baker said. "What it does is it compares what is happening inside the tank, temperature-wise. Because gas is so volatile, it expands and contracts a lot with temperature."

Baker is a technician with Petroleum Environmental Services Inc., 2442 S. 3270 West, West Valley City, and the company is unusually busy nowadays: Time is running out for owners of underground storage tanks to get on a state list of tanks that can accept fuel.

"There are approximately 3,500 facilities that we have registered with the state," said Bryan Whitaker, underground storage tank branch manager, Utah Bureau of Environmental Response and Remediation. "And of those we have approximately 190 . . . all that we have issued certificates of compliance.

"We have about 450 or so in the process. We have a long way to go."

About half of the 3,500 facilities are service stations. The rest are fleet suppliers or private companies that use storage tanks for their own purposes. Altogether, the 3,500 facilities have about 10,000 tanks.

Utah law requires that in order to get deliveries into an underground tank after July 1, a station must get what is called a "facility number." Once the deadline has passed, if any supplier delivers to a station without the number, it can be fined $500 per occurrence.

Before a certificate of compliance and the facility number can be given, the tank must be tested for present leaks, because state tank insurance won't cover existing problems. If a tank test shows that the tank is dribbling gasoline underground, the tank must be fixed.

Also, "that particular leak wouldn't be covered by the insurance," said Kenneth Alkema, director of the Utah Division of Environmental Health.

However, the tank would be covered for problems that developed later.

Between 100 and 150 tank testers have been certified in Utah. They work for about 18 companies, some of them based out of state.

Whitaker said he doesn't know how many stations have completed their paperwork but not yet filed it. However, state officials are nervous about the fact that so few have filed so far.

"We're expecting a flood of applications," he said.

"We want people to know that with the limited staff we have, we can't promise to complete the processing of those petroleum tank storage applications by July 1, unless they get them in to us by March 1."

That's why Baker and his fellow testers have been busy lately.

On that afternoon, Baker left the trailer, whose monitors were connected to a diesel fuel tank by wires, and began calibrating a five-gallon load cell. Using a tall flask, he poured 1,000 cubic centimeters of diesel fuel into the cell. That way, his computer could check the density of the fluid and set parameters for the test.

The load cell is filled about halfway with fuel. Its light-sensitive probe, which extends into the tank below, tracks the level of fuel underground.

The cell's job is to compensate for the fluctuations in the tank's volume - if a cold breeze wafts through and the volume decreases, it pumps in some diesel fuel from the load cell to equalize the level.

On the other hand, if the day heats up and the fuel expands, the device pumps some out of the tank and into the cell, keeping the level stable. The load cell can keep the fuel in the tank even to within 1/16 of an inch.

Inside the van, the computer tells the technician how much the volume ought to have changed, based on temperature - assuming the tank doesn't leak. At the end of the test, it's a simple matter to measure the fuel left in the load cell and check it against the amount that the computer says should be left.

"Hopefully, at the end of the test, if we dumped in half a gallon and the temperature said we needed to put in half a gallon, and that equals out - that's what we're hoping for. That's what the customer wants."

But if the computer says that at this temperature half a gallon should go in, but the load cell had to pump in two gallons to keep the tank level - then there was a leak.

"This system can detect 0.05 gallons per hour (leaking) with a 99 percent accuracy and a 1 percent false alarm," said Baker, who is one of four technicians employed by Petroleum Environmental Services.

"We can test up to four tanks at a time, which also helps out," said Phil Sargent, vice president of the company. "It minimizes down-time for the stores."

How many of the state's 10,000 underground tanks are leaking? When the company began testing nearly three years ago, most stations that called for the checks had questions about their own tanks. "We were averaging about an 89 to 90 percent failure rate," Sargent said.

"So it was a very significant leak problem that they were having."

Today, with all stations required to join the insurance fund, the average tank tested is newer. The valves, lines and other equipment are in better condition, so there is less likelihood of leakage.

"Statewide, we're looking at about a 25 percent failure rate. For Salt Lake, it's a little bit higher - about 30 percent," Sargent said.

A leak doesn't necessarily mean that a storage tank must be replaced. It could be a failure around a valve, for example.

After the initial precision tank-tightness test, such as the one that Baker was carrying out, a company could ask for additional tests to pinpoint the leak. "If a tank failed, there's avenues they can go to without ripping out any concrete or asphalt yet," Sargent said.

In one test, helium is pumped into the tank, and then detectors are used to find where it is seeping out. It may be possible to dig up only one part of a tank and patch it.

Now everybody is trying to get in on the act, calling for testing appointments.

"We've really seen the increase for the last week. The months of February and March are filling up fast," Sargent said.

Testing companies may find themselves putting on extra shifts. "We'll be doing this 24 hours a day," Sargent said.


(Additional information)

Insurance coverage also needed

Under federal law, owners of underground storage tanks, with certain limited exceptions, must have insurance to cover cleanup and damage costs in case the tanks leak. Tanks that dispense at least 10,000 gallons per month must have enough insurance to cover $1 million in cleanup costs and $1 million in third-party liability.

Third-party liability would occur if, for instance, a private well beside a gas station were contaminated by a plume of gasoline seeping from an underground tank. Or if gasoline fumes penetrated a neighbor's basement, "which has happened from leaking underground storage, and caused a safety hazard or a chronic health hazard," said Bryan Whitaker of the Utah Bureau of Environmental Response and Remediation.

The 1990 Legislature approved a state insurance program to help service stations and other owners of tanks. A station covered by the Utah Petroleum Storage Tank Fund must pay the first $25,000 in cleanup costs, and the insurance will pay the next $965,000.

However, the fund only provides $300,000 coverage for third-party liability, less than a third of the $1 million coverage that the federal law requires. "They're going to have to get additional coverage," Whitaker said.

For owners of between 13 and 99 tanks, the additional coverage must be obtained by April 26. Those with 12 or fewer face a deadline of Oct. 26.