06/19/92: THE TOWN OF COLUMBUS, MONTANA IS THE CURRENT OWNER OF THE MOUAT INDUSTRIES SITE #65, AND HAS OWNED THE SITE SINCE 1933. IN 1957, THE TOWN LEASED THE SITE TO MOUAT INDUSTRIES. FROM 1957 TO 1963, MOUAT OPERATED THE PROCESSING PLANT WHICH CONVERTED CHROMIUM ORE TO A HIGH GRADE SODIUM DICHROMATE, AND WHICH PRODUCED SODIUM SULFATE WASTES CONTAINING HEXAVALENT CHROMIUM. HEXAVALENT CHROMIUM LEACHED FROM THE SODIUM SULFATE WASTE PILES INTO THE SURROUNDING SOILS AND GROUNDWATER. DICHROMATE SPILLS OCCURRED DURING NORMAL OPERATION OF THE FACILITY, AND ADDED TO THE HEXAVALENT CHROMIUM CONTAMINATION. IN MAY OF 1963, MONTE VISTA ENTERED INTO AN AGREEMENT FOR THE PURCHASE OF THE CHROME PROCESSING PLANT AND THE CHROMIUM ORE STOCKPILE FROM MOUAT INDUSTRIES. MONTE VISTA OPERATED THE PROCESSING PLANT UNTIL 1967. IN 1973, THE TOWN OF COLUMBUS, MOUAT INDUSTRIES, MONTE VISTA, AND ANACONDA MINERALS ENTERED INTO AN AGREEMENT WHEREBY ANACONDA MINERALS WOULD REMOVE APPROXIMATELY 100 TONS OF SOIL AND TREAT THE REMAINING CONTAMINATED SOILS. WHEN TIMBERWELD MANUFACTURING COMPANY, A MANUFACTURER OF LAMINATED WOOD BEAMS, BEGAN OPERATING AT THE SITE IN 1975, TIMBERWELD COVERED THE AREA WHERE THE CHROMIUM PROCESSING PLANT AND CHROMATE WASTE PILES HAD BEEN LOCATED WITH A TWO FOOT LAYER OF GRAVEL AND USED THE AREA FOR A STORAGE YARD. DESPITE THESE ACTIONS, THE GRAVEL SURFACE SHOWED EVIDENCE OF SODIUM CHRO