THE CENTER OF THE SITE IS LOCATED IN THE AREA AND VICINITY OF THE ZCA FACILITY (FORMERLY KNOWN AS NATIONAL ZINC COMPANY ), LOCATED ON THE WESTERN EDGE OF BARTLESVILLE, WEST 11TH STREET, OK. THAT VICINITY, INCLUDING A LARGE SURROUNDING AREA, CONSTITUTES THE SITE. THE SITE IS LOCATED IN THE COUNTIES OF WASHINGTON AND OSAGE RESPECTIVELY. PREVIOUSLY, THE ZCA FACILITY WAS OCCUPIED BY THREE OTHER SMELTERS, THE NATIONAL ZINC COMPANY, BARTLESVILLE ZINC COMPANY AND LAN- YON-STARR SMELTING COMPANY. SINCE SITE OPERATIONS BEGAN IN 1907, THE PRIMARY FUNCTION WAS THE RECOVERY OF ZINC AND OTHER HEAVY METALS FROM ZINC CONCENTRATES AND OTHER MATERIALS. RECOVERY OF THOSE METALS INVOLVES CHEMICAL PROCEDURES AS WELL AS SMELTING OPERATIONS. PRIOR TO LATE 1976, APPROXIMATELY 1500 TONS OF PARTICULATE MATTER (CONTAINING LEAD, CADMIUM, AND OTHER HEAVY METALS) WERE RELEASED INTO THE ATMOSPHERE ANNUALLY (APPROXIMATELY 200 MILLION POUNDS TOTAL). IN LATE 1976, THE HORIZONAL RE- TORT FURNACES USED AT THE FACILITY WERE REPLACED BY ELECTRO- STATIC SMELTERS WHICH SIGNIFICANTLY REDUCED PARTICULATE STACK EMISSIONS. THE SITE WAS REFERRED TO EPA BY ATSDR AFTER ATSDR RECEIVED A LETTER OF INQUIRY FROM SENATOR DAVID BOREN. CURRENT DATA IN- DICATES THAT MOST OF THE ENVIRONMENTAL CONTAMINATION AT THE SITE IS DIRECTLY RELATED TO HISTORICAL SMELTING OPERATIONS FROM 1907 THROUGH 1976. AFTER DETAIL