06/19/92: THE BUTTE PRIORITY SOILS OPERABLE UNIT, WHICH IS A PART OF THE SILVER BOW CREEK BUTTE SITE, CONSISTS OF FORMER AND ACTIVE MINING, MILLING, SMELTING, AND RELATED FACILITIES, ASSOCIATED WASTE ROCK AND MILL TAILINGS WASTES, A NETWORK OF RAILROAD TRACKS AND SPURS CONSTRUCTED OR CONTAMINATED WITH MINING RELATED WASTES, AND ASSOCIATED CONTAMINATED SOILS IN BUTTE AND WALKERVILLE, MONTANA. THE MINING WASTE DUMPS, MILL AND SMELTER WASTES, AND ASSOCIATED CONTAMINATED SOILS AT THE COLORADO SMELTER SITE WITHIN BUTTE WHICH ARE THE SUBJECT OF THIS REMOVAL ACTION, CONTAMINANT SOURCES OF HAZARDOUS SUBSTANCES WITHIN THE CITY OF BUTTE AND THE SILVER BOW CREEK BASIN.