The Atlantic Richfield Co. (ARCO) has agreed to a tentative settlement with Utah and the Environmental Protection Agency in the cleanup of mill tailings at the Sharon Steel Superfund site.

Lawyers from ARCO and the Department of Justice refused to reveal how much the Los Angeles-based company will pay.They told U.S. District Chief Judge Bruce Jenkins Wednesday that a settlement may be signed by Nov. 8. The public would have 30 days to comment.

The trial to determine cleanup costs, which began Oct. 9, was scheduled to last two months. But the hearing was postponed last week to give lawyers time to negotiate a settlement.

"To say the last week has been arduous would be a monumental understatement," said government attorney Benjamin Fisherow. "But we're here now to advise the court that we have a deal."

Concentrations of lead, arsenic and cadmium in mill tailings piled 40 feet high at the 260-acre site near downtown Midvale are hazardous to residents and are polluting groundwater, Fisherow said.

"We've said the tailings are a health risk and we're still saying they are a risk," said Fisherow.

ARCO lawyers have argued concentrations of heavy metals are too low to pose a danger.

ARCO is the last defendant to settle in a 1986 suit brought by the government to force companies to pay costs to clean up the 14 million cubic tons of tailings.

Sharon Steel agreed in August to pay $22 million in cash or $82 million in mixed cash and bankruptcy claims.

A trust representing the defunct UV Industries agreed to turn over 60 percent of its assets, amounting to as much as $18 million, toward the cleanup.

The EPA has recommended capping the tailings pile and treating groundwater at a cost of about $35.5 million. The state and Midvale City claim a covered pile posses a health risk and has urged the EPA to move the tailings to a western Utah desert landfill at a cost of about $40 million.