LUNDAY-THAGARD MANUFACTURES ROAD-GRADE AND ROOFING GRADE ASPHALT AT ITS SOUTH GATE, CALIFORNIA, OIL REFINERY. ALTHOUGH FROM 1983 TO 1992 THE FACILITY CONSISTED OF AN ASPHALT MANUFACTURING PLANT, A PAPER MILL, AND A ROOFING MATERIALS PLANT. SUBSEQUENTLY, LUNDAY-THAGARD CLOSED THE PAPER MILL AND SOLD THE ROOFING MATERIALS PLANT TO IN-NOVATE. THROUGH A SINGLE CONNECTION, LUNDAY-THAGARD DISCHARGES INTO THE SEWERS A COMBINED AVERAGE OF ABOUT 40,000 GALLONS PER DAY OF TREATED INDUSTRIAL WASTEWATER FROM ITS ASPHALT PLANT IN IN-NOVATE'S ROOFING MATERIALS PLANT. THE WASTEWATER IS THEN CONVEYED THROUGH THE SEWERS TO THE COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY'S SEWAGE TREATMENT PLANT FOR TREATMENT AND DISPOSAL INTO THE SANTA MONICA BAY. ALL FACILITIES THAT DISCHARGE INDUSTRIAL WASTEWATER TO SEWAGE TREATMENT PLANTS ARE REQUIRED TO COMPLY WITH LOCAL LIMITS DESIGNED TO PROTECT THOSE TREATMENT PLANTS. SINCE MARCH 23, 1980, ALL EXISTING PETROLEUM REFINERIES THAT DISCHARGE TO SEWAGE TREATMENT PLANTS HAVE BEEN REQUIRED TO COMPLY WITH THE CATEGORICAL PRETREATMENT STANDARDS GOVERNING THE CHARACTER OF THEIR INDUSTRIAL WASTEWATER. IN ADDITION, ALL FACILITIES THAT ARE SUBJECT TO A CATEGORICAL PRETREATMENT STANDARD MUST SUBMIT SEMIANNUAL SELF-MONITORING REPORTS TO THE CONTROL AUTHORITY. SINCE AUGUST 1989, LUNDAY-THAGARD HA