LIVINGSTON, Mont. (AP) - Cleanup of an estimated 1 million gallons of diesel fuel in the groundwater and soils beneath railroad yards here has restarted after a 10-year lapse.

Plans call for more underground exploration related to chlorinated solvents that taint a large plume of groundwater.

Dealing with the pollution is the responsibility of the railroad BNSF, which left Livingston in 1986. BNSF and its corporate forerunners dumped and spilled the fuel and solvents during decades of railroad operations here.

After a spate of cleanup in the late 1980s and '90s, work halted.

In the 1990s, about 3,600 gallons of diesel fuel were removed, "but nothing's been done since," said Aimee Reynolds, project manager for the Montana Department of Environmental Quality.

The renewed action came after Gov. Brian Schweitzer, in March, accused the company of "lawyering" to delay the cleanup. Schweitzer said at the time that he would order the cleanup completed, and send BNSF the bill. Staff changes and funding problems at DEQ also added to the problems.

A detailed work plan has since been completed.

"BNSF has worked with state DEQ and agreed to a plan to continue remedial actions," railroad spokesman Gus Melonas said Wednesday.

"It's night and day, from the way things had been going before," said Jim Barrett, Park County Environmental Council executive director.

On Wednesday, work began on the first of 16 wells to be drilled as part of a pilot project to test methods and equipment.

The wells will reach into the aquifer and pump water, creating a "cone of depression." When that cone fills with the diesel floating on the aquifer, those fluids can be pumped out.

Water removed from the pumps must be treated before it can be sent to the city's sewage treatment plant.

By next year, a total of 48 wells will be installed, Reynolds said. All will be compatible with pumping or "bioventing," a process that injects air into the ground and invigorates microbes that decompose diesel naturally.

Not all the diesel can be pumped out. That is because much of it is contained in a 6-foot-thick "smear," consisting of rock and gravel coated with fuel. The bioventing could help with that problem.

Reynolds said the project's cost is an estimated $9 million if the state does the work and sends BNSF the bill, which it has the legal right to do. BNSF might be able to save money by hiring contractors, she said.

The state also is ordering dozens of new wells intended to delineate the size and severity of the plume of volatile chlorinated solvents, called VOCs. Some of the chemicals are listed as probable causes of cancer.

Montana has about a dozen similar state Superfund sites for which BNSF is responsible.