SITE ENCOMPASSES THE TRI-COUNTY AND ELGIN LANDFILLS, WHICH WERE DESIGNATED AS ONE SITE BECAUSE SAMPLING RESULTS INDICAT ED THAT CONTAMINANTS FROM BOTH WERE COMMINGLED. TOTAL ACREAGE APPROXIMNATELY 66 ACRES. HAZ. SUBSTANCES HAVE BEEN ANDARE THREATENED TO BE RELEASED FROM THE SITE. COMMERCIAL INDUSTRIAL AND DOMESTIC WASTES WERE DISPOSED OF, AND MIGRATI ON AND DEGRADATION OF THESE WASTES RESULTED IN A RELEASE OF HAZ. SUBSTANCES. EPA HAS UNDERTAKED RESPONSE ACTIONS AT THE SITE AND WILL ALSO DO SO IN THE FUTURE. ON 2/2/94 EPA ENTERED INTO AN AOC WITH WASTE MGMT AND BROWNING FERRIS THE REMEDIAL DESIGN RESULTING FROM THIS ORDER WAS COMPLETED AND APPROVED BY EPA 9/30/97. NEGOTIATIONS WITH BFI AND WMI WERE OFFICIALLY TERMINATED 8/26/98. BECAUSE OF THE DEFERRED GROUNDWATER COMPONENT, THIS SITE MAY NOT STRICTLY QUALIFY AS A CONSTRUCTION COMPLETION UNTIL THE GROUNDWATER COMPONENT IS EITHER CONSTRUCTED OR ELEMINATED. THE GROUNDWATER CONTAMINATION AT THE SITE WILL BE ADDRESSED BY NATURAL ATTNUATION, ONCE THE PLACEMENT OF THE LANDFILL CAP AND ACTIVE LANDFILL GAS COLLECTION SYSTEM IS COMPLETED. A SUBSEQUENT RECORD OF DECISION (ROD) AMENDMENT WILL BE REQUIRED IN THE EVENT THAT NATURAL ATTENUATION IS ACCEPTED AND FINALLY CHOSEN AS THE FINAL TREATMENT FOR THE CONTAMI- NATED GROUNDWATER. THE TRI-COUNTY/ELGIN LANDFILLS ARE FUNCTIONALLY ONE CONTI- GUOUS DISPOSAL UNIT WITH SEPARATE OW