COLUMBIA, S.C. - Companies and their employees who intentionally harm the environment could face state grand jury investigations under legislation expected to clear the Senate on Thursday.

The legislation, seen as a key tool for the attorney general's office in prosecuting environmental crimes, won second reading Wednesday and is expected to get final approval Thursday before going to the House, which is considering similar legislation.

Companies would have to cause more than a $1 million in damages before the state grand jury could investigate.

The bill will "protect the state from those people who intentionally violate the state's laws," Sen. Jake Knotts, R-West Columbia, said.

Sen. Dick Elliott, D-North Myrtle Beach, spoke against the legislation Wednesday, finally winning changes in the bill that clarified how it would work. "I think we got a better bill," Elliott said.

It still has a shortcoming, Elliott said, because the definition of what may be an environmental crime is too broad. For instance, there's no clear definition on wetlands, he said.

Knotts has tried to get a bill through the Legislature "that had teeth in it" ever since a 2000 chemical spill at Tin Products, a Lexington County chemical company, killed thousands of fish and contaminated two waterways.

Under the bill, the state Department of Health and Environmental Control will conduct investigations and call on the State Law Enforcement Division and the state attorney general if they find evidence of intentional violation of state law and have an independent estimate showing the potential damage of cleanup costs could be $1 million or more.

DHEC would not make the decision to prosecute. The attorney general would refer cases for grand jury investigation, Knotts said.

Knotts said companies also are protected from simultaneously state and federal prosecution.

The legislation isn't meant to go after companies with minor pollution problems, Knotts said.

"It's solely for those people who are intentionally, knowingly or willfully violating the environmental laws," Knotts said. "It prevents a witch hunt. The last thing we want is a witch hunt."