WAPATO, Wash. — After finding asbestos in a huge pile of illegally dumped waste on private property southwest of town, investigators from the U.S. Environmental Protection Agency returned this week to remove more samples for testing.

Investigators will have removed 10 semitruck loads by Friday, but that will only account for about 2 percent of the massive pile in the 3900 block of Ashue Road on the Yakama reservation, said Jeff Fowlow, a scene coordinator for EPA.

“It’s a big pile of stuff,” he said from the site Tuesday. “What we’re doing is more surgical. We’re trying to find out what all is in this pile.”

The illegal dump was discovered late last year when a nearby resident reported seeing trucks dumping waste there from the demolition of the old Wapato High School.

School officials said they were not aware of the dumping and that language in contracts with demolition crews specified how waste, including hazardous material such as asbestos, should be disposed.

Last October, investigators found asbestos on large concrete blocks that came from the demolition of the old school the previous summer, Fowlow said.

He said at least 400 truckloads of waste had been dumped onto the property, and that it appears other dumpings had taken place there prior to the school demolition project.

The property owner couldn’t be reached for comment, but Fowlow said he’s cooperating with authorities.

“He’s given us access,” Fowlow said. “I think he sees some mistakes have been made and that there’s been illegal dumping on his property — there’s no question about that.”

The property owner and the demolition contractor could face sizable fines and be on the hook for the work EPA is now doing, which is estimated at $175,000, as well as for cleaning up the entire pile, said EPA spokesman Mark McIntyre in Seattle.

He wouldn’t speculate on any cost range of possible fines, saying that it would depend on the amount of hazardous material found and the number of times waste was dumped there, he said.

EPA may clean it up, and then order the property owner, the contractor and whomever else is deemed responsible to reimburse the federal agency, he said, explaining that it was too early in the investigation to determine when cleanup would begin.

“Right now we’re just going in there with a sharper point to find out just how much (hazardous material) is there and what it’s going to take to clean it up.”

Phil Ferolito can be reached at 509-577-7749 or pferolito@yakimaherald.com.