BUTTE, Mont. (AP) -- A former oil producer says it has spent more than $1.4 billion on the decades-long Butte Superfund cleanup and expects to spend at least $100 million more.

The Montana Standard reports that the financial information shared this week by a spokesman for Atlantic Richfield Company is the first disclosure of the company's spending. The total includes investigation, remediation and restoration work on the site.

Butte was declared a federal Superfund site in 1983 because of the damage done by more than a century of mining and smelting. Butte-Silver Bow officials say more than 600 acres of land have since been remediated and reclaimed.

U.S. environmental officials began accepting comments this month on a proposed final plan for the cleanup.