THE TUCSON INTERNATIONAL AIRPORT AREA IS LOCATED IN PIMA COUNTY, IN SOUTHEASTERN ARIZONA. IT ENCOMPASSES SEC- TIONS OF SOUTHWEST TUCSON, AS WELL AS ADJOINING LANDS SOUTH OF THE CITY. THE SITE WAS LISTED ON THE NPL ON SEPTEMBER 8, 1983. THE SITE WAS LISTED ON THE NPL BECAUSE OF GROUNDWATER CON- TAMINATION (PRIMARILY TCE). THE ROD WAS SIGNED ON AUGUST 22, 1988. OUR INFORMATION INDICATES THAT THERE ARE THREE DISTINCT PLUMES OF CONTAMINATION IN THE AREA. THE MAIN AREA OF CONTAMINATION HAS BEEN DENOMINATED AREA A. TWO SMALLER PLUMES TO THE EAST OF THE MAIN PLUME HAVE BEEN DENOMINATED AREA B. BASED ON THE REMEDIAL INVESTIGATION, WE HAVE IDENTIFIED 2 PRPS FOR THE EASTERNMOST PLUME IN AREA B. BURR-BROWN RESEARCH CORPORATION & WEST-CAP CORPORATION. GENERAL NOTICE LETTERS WERE SENT TO THESE PARTIES IN AUGUST 1987. WE SENT SPECIAL NOTICE LETTERS FOR THE RD/RA ON JULY 11, 1988 AND RECEIVED A GOOD FAITH OFFER ON SEPTEMB- ER 8, 1988 FROM BURR_BROWN. WE HAVE BEEN NEGOTIATING AN RD/RA CONSENT DECREE WITH BURR-BROWN SINCE SEPTEMBER 2, 1988. MOST OF THE LEGAL &TECH NICAL ISSUES HAVE BEEN NEGOTIATED. THE 120-DAY NEGOTIATION MORATORIUM WILL END ON NOVEMBER 8, 1988. WE WILL REQUEST A 30-DAY EXTENSION FROM THE REGIONAL ADMINISTRATOR TO ENABLE US TO CONTINUE NEGOTIATING UNTIL DECEMBER