THE OCTOBER 15, 1981, CONSENT DECREE COVERS THE AJO AND MORENCI, ARIZONA COPPER SMELTERS OWNED BY PHELPS DODGE AND RESOLVED A CIVIL ACTION FILED ON MARCH 26, 1981 FOR VIO- LATIONS OF THE ARIZONA STATE IMPLEMENTATION PLAN. THIS CONSENT DECREE WAS THE FIRST INVOLVING A PRIMARY COPPER SMELTER AND IT REQUIRES COMPLIANCE WITH BOTH THE SULFUR DI- OXIDE (SO2) AND PARTICULATE (TSP) ARIZONA STATE IMPLEMEN- TATION PLAN (SIP) EMISSION LIMITATIONS. UNDER THE 1981 CONSENT DECREE, THE AJO AND MORENCI SMELTERS ARE TO ACHIEVE COMPLIANCE BY DECEMBER 31, 1985 AND JANUARY 1, 1985, RESPECTIVELY, BY USE OF INNOVATIVE COPPER SMELTING TECHNOLOGY. THIS TECHNOLOGY IS REFERRED TO AS OX- YGEN ENRICHMENT OR OXYGEN SPRINKLE SMELTING. STRONG STREAMS OF PROCESS GASES ARE PRODUCED OF WHICH 3.5% ARE SO2. A NEW SULFURIC ACID PLANT THEN PROCESSES THE GAS TO PRODUCE SUL- FURIC ACID AS A BY-PRODUCT WHICH CAN BE SOLD. PARTICULATES ARE REMOVED FROM THE GAS STREAMS BEFORE ENTERING THE ACID PLANT. DURING THE INTERIM PERIOD OF THE DECREE THE SMELTERS ARE REQUIRED TO USE SUPPLEMENTAL CONTROL SYSTEMS (SCS) TO PROTEST THE SO2 NATIONAL AMBIENT AIR QUALITY STANDARD. SCS DOES NOT REDUCE EMISSIONS BUT VARIES EMISSIONS ACCORDING TO THE PREVAILING METEOROLOGICAL CONDITIONS. DURING PERIODS OF LITTLE WIND DISPERSION, THE EMISSIONS ARE CUT BACK. SECTION 123 OF THE CLEAN AIR ACT PROHIBITS RELIAN