Laboratory tests have determined that barrels found last month illegally dumped on Prince William County land contain hazardous organic solvents, but it is unclear what the parent product might have been, authorities said this week.

Laidlaw Environmental, a hazardous waste disposal company, which collected samples from some of the barrels June 22, identified the substances as toluene, xylene, methyl ethyl ketone and acetone. The solvents are all classified as hazardous waste, but are not in the class determined to be extremely dangerous, said John Medici, county hazardous materials officer.

"It's going to be impossible to take a profile of these chemicals and determine what the parent product might have been," said Medici. He said that the original product could have been paint thinner.

Fourteen 55-gallon barrels were found June 18 by Army Corps of Engineers surveyers near Spriggs and Dumfries roads. Two barrels were empty, two were full and 10 were found lying sideways and gouged open with an ax.

The open containers were oozing a material that smelled and looked like paint thinner, Fire Marshall John O'Neal said in an earlier interview.

Darrell James Sturgell, 47, owner of D&K Auto Body of Dumfries, was arrested July 11 and charged with felony illegal dumping. Sturgell is free on bail pending a preliminary hearing on Wednesday, court officials said.

Sturgell's business was identified as the source of the barrels because of a small black-and-white sticker affixed to one of the containers bearing the name of his business, O'Neal said.

The Prince William County Attorney's Office was granted permission by the Board of County Supervisors on Tuesday to pursue a civil lawsuit to recover the costs of the cleanup, which are expected to exceed $500,000, said Assistant County Attorney Angela Lemmon.

Laidlaw chemist Rich Malinowski said the cost of removing barrels containing hazardous materials from a business is about $300 a barrel.

Authorities called the incident the worst illegal dumping in the county's history. More than 100 trees will have to be cut down, a wetland area will have be excavated, and several tons of dirt will have to be dug up and replaced, authorities said.

"People just can't imagine the difficulty this thing is going to cause to get the site cleaned up," Medici said.

On Monday, officials from the state Department of Health collected samples of ground water near the dump site to determine if underground water supplies had been contaminated, Medici said. The results won't be known for several days, but the initial investigation does not indicate contamination, Medici said.

A special prosecutor from the Department of Justice was expected to visit the county this week to investigate and determine if federal charges will be filed in the case, Medici said.

The county, which has spent about $50,000 to cover the containers with larger barrels and to pay for initial tests, has also ordered a road cut to the barrels. The dumping occurred on an old farm site. Brush has also been removed to allow surveyers to get into the site to mark property lines, Medici said.

Authorities are investigating the possibility that the dumped materials have run from county property onto a neighboring plot owned by NV Land, a real estate development company, he said.

NV Land engineer Alan Roberson, who was with the surveyers when they discovered the barrels June 18 while surveying nearby wetlands, said the dumping site is about 50 or 60 feet from the company's property. The chemicals have run onto the developer's land, he said.

"Another 60 or 70 feet and this would have been our responsibility," said Roberson, adding that the county will pay to clean up NV's property. "Or if we hadn't gone out there when we did, the dumping might not have been found for a long time and would have spread even more."

The next step will be for a contractor to conduct a detailed site survey to determine the extent of the contamination. Then a contractor will be hired to recommend a cleanup plan. Both projects will go out for bid, Medici said.

The soil will have to be incinerated because of laws regulating the disposal of methyl ethyl ketone. The incineration, which will destroy the organic materials, will be conducted either at facilities in Louisiana or Arizona that are equipped to do the work, or the county might opt to rent an incinerator and have it brought to the site, Medici said.