Next time you fill your car's gas tank, consider this. The gas station is a far more environmentally friendly place than it was even a few years ago. Environmental regulations begun in 1988 have brought about some impressive improvements.

Doyle Dominy, the owner of several gas stations, in Dublin Georgia, enjoys pointing out the changes. If you were to tour one of his gas stations with him, he'd probably start by telling you about his underground gas tanks.

Like most gas stations, Dominy's stations dispense three grades of gasoline. Surprisingly, however, the three grades come from only two underground tanks. "This is typical," he says. "Most companies blend from two tanks to get their three products. It's good to do it this way," he continues. "With fewer tanks, there's less risk of leaks and contamination."

The tanks themselves are also different from what they would have been even a few years ago. In the past, tanks were made of steel that could, over time, corrode. Today's tanks, by law, are non corrosive. Typically they're made of fiberglass. "These tanks should last more than 40 years before we have to drain and replace them," he says.

Many of the fiberglass tanks today have double walls. It's like having one tank encased inside a larger tank. "If one wall were to crack," points out Dominy, "the second wall is there to keep the gas from leaking into the ground."

The fiberglass tanks are buried 12 to 14 feet down and each one is encased in two feet of fine gravel. The gravel is there as a backup to absorb leaks in the unlikely case that both walls of the fiberglass tank were to fail.

When a tanker truck delivers gas to either of the two underground tanks at Dominy's filling station, there's a clever safeguard to protect the soil and groundwater from accidental drips. To visualize how it works, imagine that a tanker truck has just pulled up to the gas station. The driver attaches a large hose from the tanker to the underground pipe leading to the gasoline storage tank.

But what if some of the gas drips out of the nozzle before it's fully connected to the pipe? The drips would be caught in a wastebasket-size basin that surrounds the pipe. The basin itself can be drained, and the net effect is that an accidental spill of a few drops or a few gallons will be trapped instead of going into the surrounding soil.

All the pipes attached to the storage tanks are equipped with highly sensitive leak detectors. "Any leak whatsoever should be detected," says Dominy, explaining, "Even the smallest leak causes a detectable difference in pressure." If a leak detector should discover a leak, it sets off a highly audible alarm, and the station attendant can take corrective action immediately.

Besides the leak detectors, Dominy and his colleagues in the industry have an additional check on the integrity of the tanks and pipes. They locate monitoring wells at several points near the underground tanks and also along the paths of the underground pipes. Gas station officials frequently take samples of ground water to check yet again that there's been no leakage.

Dominy doesn't pretend that the system is perfect, but he's sure that there have been improvements. "I feel good about the cooperation between the EPA and the petroleum marketers," he says. "We're working together to keep the soil and water for future generations from being contaminated."