Eleven years after a massive gasoline leak from Blue Bell Gulf tainted groundwater and sent vapors through a swath of Whitpain Township, the problems it caused haven't been solved.

The cleanup bill for the 13,000-gallon leak is $12.1 million and climbing. Dozens of neighbors of the former station are a decade into a court fight over the pollution that remains years from a tidy ending. The gas station's owner, now unemployed, is trying to get off the hook for the entire cost of the mess.

And on a recent gray day, a rainbow-hued cloud slid along the surface of a pond in this sedate Montgomery County suburb.

"Look at the sheen of gas here," Christine Fisher of Blue Bell said at a pasture where she once fed a horse and goat. "After a rain, we find these little puddles of sheen back in the woods here, still."

State inspectors, too, are still finding remnants of the pollution while checking groundwater with 40-foot-deep test wells. A water-pumping treatment system brought the pollution down to a level considered safe by Pennsylvania standards, but some gasoline additives are likely to linger in Whitpain's groundwater for years.

"We can't really clean up groundwater," said professor Laura Toran, chair of environmental geology at Temple University. "It's a myth. You can protect the soil zone, and you can keep it away from some of the groundwater. But cleaning it up? That's a really tough row to hoe."

Despite the long string of problems it would cause, the largest gasoline spill in recent Southeastern Pennsylvania history eluded authorities' attention for months.

In the spring of 1998, a problem with the underground tanks of Blue Bell Gulf caused gasoline to seep out, but station owner Thomas F. Wagner didn't immediately notice it. The gas drained into the soil and into groundwater beneath the bustling intersection of Skippack Pike and Penllyn Blue Bell Pike for up to two months.

By May 8, 1998, enough gas had spread that pent-up vapors in a well's pump house across the road from the station caused an explosion, causing little damage but drawing the first widespread attention to the problem.

Shortly before the explosion, Wagner had learned he had a leak and contacted the state Department of Environmental Protection, said his attorney, John Mattioni.

"He followed the correct protocol," Mattioni said.

The leak was stopped, and Wagner told the DEP that only a few gallons had spilled.

The magnitude of the problem, however, hadn't yet been discovered.

Seven weeks later, on June 30, dangerously thick gasoline vapors were found in a house a quarter-mile away. Only then did a full DEP investigation reveal the extent of the pollution, with dozens of neighbors reporting problems. The DEP estimates that at least 13,000 gallons spread a half-mile under the heart of Blue Bell that spring.

Much of the cleanup expense so far has come from the $5.5 million construction of a water-treatment plant in a hulking corrugated-metal building on township land behind Joan Thurman's house in the Village Circle subdivision. Outside her front windows, quiet, winding streets became speckled with dozens of freshly dug test wells.

"We'd wake up in the morning and find a backhoe on the lawn," said Thurman, 77.

The DEP assessed that the plant might have to run 10, 20, perhaps 50 years to undo the damage in the water beneath the residential area.

Five years after a water-treatment system at the gas station site began working, the larger facility's pumps were turned on in 2004 and shut down in 2007, after tests showed the groundwater's pollution was as low as the plant could get it.

"It was nearly as if we were pumping clean water relative to what the system could do," DEP spokesman Dennis Harney said.

The building still stands, ready to be switched back on if the state's quarterly checks of 31 nearby test wells find a rise in contamination. That hasn't happened, but officials also have not yet given the go-ahead to empty the building of its equipment and hand it over to the township, as is eventually planned.

"It might take years," said Phyllis C. Lieberman, township manager.

Two environmental-consulting firms hired in 2005 to manage the spill have cost the state a combined $620,000 and are still working at it, Harney said.

Toran said water-treatment pumps fail at completely cleaning up 85 percent of the spills where they're used. Groundwater flows into underground crevices that pumps can't easily pull it out of. Once a hardy chemical such as the gasoline additive methyl tertiary butyl ether (MTBE) flows into it, the contamination can hang around for decades despite efforts to remove it.

State inspectors' January check found MTBE in 17 of the 31 test wells.

The gasoline fouled about a dozen homes' drinking-water wells, including Christine and Warren Fisher's, forcing them to switch to public water permanently.

In the complex court battle that ensued, the Fishers were among 45 neighbors who sued Wagner and his equipment suppliers over the chemicals' danger. (Two other homeowners settled; one declined to comment, and the other could not be reached.) The case was split several ways to sort out legal responsibility and other issues, and only four homeowners have gone to trial.

After a month in court in 2007, they lost, but the matter is up for appeal in a quest to reassemble all 45 plaintiffs for one trial.

"These cases are complicated," said Brendan Collins, one of their attorneys, "but there is no reason why this case could not have been tried prior to 2007."

That the case is still coursing through the legal system has frustrated some plaintiffs.

On a rainy Monday last month, six of them picketed the Norristown courthouse to complain about the delay and the piecemeal trials.

"No jury will get the total picture of this environmental impact unless they hear from all of us," said Christine Fisher, 72.

While their fate - and their neighborhood's health - is still being calculated, the Blue Bell Gulf station has been wiped off the landscape. A bank replaced it, and Wagner, who is in his 60s, is unemployed and on disability.

The DEP contends Wagner is liable for the $12.1 million in cleanup expenses, plus interest, but that, too, is something the courts have to sort out. Wagner contended in court that his equipment suppliers bore the liability.

"We're sitting here in sort of a limbo state," said Mattioni, Wagner's lawyer.