THE SITE INCLUDES AN AREA WHERE FORMER WOOD PRESERVING OPERATIONS OCCURRED BEGINNING IN THE LATE 1950S. THE PROCESS CONSISTED OF PRESSURE TREATING WOOD WITH CREOSOTE, PCP AND, PERIODICALLY, WATER SOLUBLE METAL SALT PRESERVATIVES. WASTEWATER GENERATED AS A RESULT OF THE WOOD TREATING OPERATIONS WAS DISCHARGED TO WASTEWATER DISPOSAL PONDS ON THE SITE BETWEEN 1957 AND 1971. THESE PONDS WERE COVERED WITH SAND AND REPLACED BY A NEW WASTEWATER DISPOSAL POND WHICH WAS UTILIZED FOR THE SAME PURPOSE UNTIL 1980. SLUDGE FROM THE WOOD TREATMENT FACILITY AREA WAS DISPOSED OF AT A LANDFILL WITHIN THE SITE. IN 1977, MPCA DETERMINED THAT HAZARDOUS SUBSTANCES HAD BEEN RELEASED FROM THE SITE. MONITORING WELLS REVEALED THE PRESENCE OF PCP, PAHS, PHENOLS, PCDD, PCDF, AND METALS. ON SEPTEMBER 21, 1984, U.S. EPA PLACED THE SITE ON THE NPL. IN OCTOBER 2001, U.S. EPA PERFORMED A FIELD INVESTIGATION AT THE SITE TO FURTHER EVALUATE ISSUES RAISED AS A RESULT OF THE 2000 FIVE-YEAR REVIEW. SIX OF THE SOIL SAMPLING INDICATED DIOXIN LEVELS IN EXCESS OF 1 PPB. IN JULY 2003, U.S. EPA ISSUED A CERCLA SECTION 106 UAO TO IP FOR THE PERFORMANCE OF REMOVAL SITE EVALUATION AND SUPPLEMENTAL ASSESSMENT SAMPLING AT THE SITE. THE SAMPLING INDICATED VALIDATED DATA RESULTS CONFIRMING EARLIER FINDINGS (AND PRODUCING NEW FINDINGS) OF DIOXIN OVER THE 1 PPB LEVEL IN VARIOUS LOCATIONS THROUGHOUT THE SITE. SOME OF THESE LOCATIONS ARE PROXIMATE TO RESIDENTIAL AREAS. SOME OF THESE LOCATIONS ARE ON PROPERTY OWNED BY BNSF. BASE