IROQUOIS FOUNDRY PRODUCES GREY IRON CASTINGS FROM SCRAP METAL. EMISSION SOURCES AT THE PLANT INCLUDE A CUPOLA FURNACE WHICH WAS INSTALLED IN 1978. INSPECTIONS CONDUCTED BY THE STATE IN 1997, DOCUMENTED VIOLATIONS OF OPACITY AND CARBON MONOXIDE (CO) REGULATIONS AT THE CUPOLA. STACK TESTS CONDUCTED IN RESPONSE TO USEPA'S REQUEST ALSO SHOWED EXCEEDANCES OF THE PM LIMITS CONTAINED IN THE WISCONSIN SIP. TO COMPLY WITH THE CO AND PM LIMITS, IROQUOIS INSTALLED AN AFTER BURNER FOR THE CUPOLA AND UPGRADED THE VENTURI SCRUBBER SYSTEM. THIS CASE WAS RESOLVED BY ISSURING A CACO AND A 113(A) ORDER.