NATURE OF THE CASE BAYOU STEEL CORPORATION (OF LAPLACE) OPERATES A STEEL MANUFACTURING AND FORMING FACILITY IN ST. JOHN THE BAPTIST PARISH, LOUISIANA. PROCESS UNITS INCLUDE TWO ELECTRICAL ARC FURNACES, TWO CONTINUOUS CASTING UNITS, AND HOT ROLLING MILL EQUIPMENT. EMISSIONS FROM THE FACILITY ARE SUBJECT TO NEW SOURCE PERFORMANCE STANDARDS (NSPS) AND PERMIT PSD-LA-066, ISSUED TO BAYOU STEEL ON MARCH 30, 1978. CAUSE OF ACTION BAYOU STEEL BEGAN OPERATION IN 1981 WITH A FACILITY BASED ON A GERMAN DESIGN. THE FACILITY SHOULD HAVE BEEN ABLE TO MEET THE OPACITY LIMITS OF NSPS AS WELL AS MORE STRINGENT BACT VISIBLE EMISSION LIMITS ON THE PSD PERMIT. HOWEVER, THE SOURCE IS EXPERIENCING OPACITY VIOLATIONS, APPARENTLY DUE TO MISDESIGN OF THE SECONDARY CONTROL SYSTEM. BAYOU STEEL COLLECTS EMIISIONS FROM CHARGING AND TAPPING OPERATIONS IN CANOPY HOODS OVER EACH FURNACE, RATHER THAN VENTING EMISSIONS DIRECTLY INTO THE ATMOSPHERE. THE HOODS VENT TO SIX BAGHOUSES, KNOWN AS STUB STACKS, LOCATED ON THE ROOF OF THE BUILDING. APPARENTLY, HEAT FROM THE CHARGES/TAPS HAD NOT BEEN FULLY EVALUATED PRIOR TO DESIGN. SPARKS AND THE COMPANY HAS EXPRESSED CONCERN THAT AN OPEN ENFORCEMENT HEAT SPIKES BURN THE BAGS, DECREASING THE EFFICIENCY OF THE BAGHOUSE. HEAT SPIKES AT THE ENTRANCE OF THE BAGHOUSE REACH 1000 DEGREES F. NSPS LIMITS OPACITY TO 2