(CN) — Adding to its $1.4 billion already spent on cleaning up former mining sites near Butte, Montana, Atlantic Richfield Company has agrred to pay another $28 million for mining cleanup costs in Anaconda, Montana.

Anaconda is just 25 miles from Butte, which for over a century has been billed as “The Richest Hill on Earth” for its vast copper reserves.

With the agreement, Arco will continue to pay for cleanup costs, remediation efforts and fund community-development projects in the town of Anaconda. Tuesday’s agreement includes $28.7 million in community development funding over the next 25 years, including about $9 million to be paid within the first year.

Copper is still mined in Butte, but in the town’s former heyday the ore was hauled by rail to nearby Anaconda for smelting. Although the Anaconda smelter closed in 1980, smelting operations left behind dispersed contaminants, including arsenic, over more than 300 square miles, according to the U.S. Environmental Protection Agency.

Butte and nearby Anaconda were declared federal Superfund sites in 1983. Arco had purchased the former smelter operator, Anaconda Minerals Company, in 1977 and assumed that company’s liabilities.

Approximately 20,000 acres of soil were severely impacted by airborne emissions and millions of gallons of groundwater were polluted, according to the EPA.

Bill Everett, Anaconda-Deer Lodge County chief executive, on Tuesday laid out the details of the agreement with Arco for cleanup costs and community development. The agreement provides $3 million in economic development funds in the first four months, which Everett told The Associated Press is already set aside to assist in a $10 million hotel complex project in Anaconda.

The agreement’s public health provisions also include an expanded attic dust removal program and an expansion of a yard-soil replacement program; water-well testing for residents; and $500,000 to be put in an interest-bearing account to replace wells and provide bottled water for residents whose wells have high contaminant levels.

Large amounts of smelting slag and tailings were produced in Anaconda, an historic Montana town with quaint brick buildings and turn of the century architecture. It’s a town that is trying to move forward, while having to clean up its mining past, and in fact Anaconda has done some creative things with the jet-black mining slag left over from copper smelting. In 1997, Anaconda opened the Old Works Golf Course, a Jack Nicklaus signature course. Nicklaus used the black slag, an inert substance, for his bunkers on the golf course.

Arco’s history dates to 1866, when Atlantic Refining formed and was purchased by Standard Oil. In 1966, Atlantic Refining and Richfield Oil merged to form Arco, which joined the British Petroleum group in 2000.

According to The Associated Press, Texas-based Arco said in April that it had spent more than $1.4 billion on the decades-long Butte Superfund cleanup and is expected to spend at least $100 million more.

In a 2013 settlement, a Montana federal judge ordered Arco to reimburse the EPA for over $21 million of its cleanup costs at the Anaconda Smelter Site and nearby areas for cleanup costs between 2002 and 2010, according to the EPA.

After public input is taken over the next five weeks, the Anaconda-Deer Lodge County Commission will vote whether to send the new financial agreement to the federal court overseeing the Superfund lawsuit.

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