IMOINDUSTRIES OWNS AND OPERATES A FACILITY IN VERNON, CA. WHICH MANUFACTURES PRESSURE AND TEMPERATURE-SENSITIVE SWITCHES, TRANSDUSERS AND VALUES. THE VERNON PLANT DISCHARGE INTO THE COUNTY SANITATION DISTRICTS OF LOS ANGELES COUNTY JOINT WASTEWATER VIOLATION OF THE CATEGORICAL PRETREATMENT STANDARDS FOR METAL FINISHING OPERATIONS. IN ADDITION, IMO INDUSTRIESVIOLATED THE PROHIBITIONS AGAINST DILUTION AS A SUBSTITUTE FOR TREATMENT BY CONTINUOUSLY RUNNING ITS RINSES EVEN WHEN METAL FINISHING PROCESSES WERE NOT IN OPERATION. AS OF NOV 1991, IMO INDUSTRIES DOES USES OUTSIDE CONTRACTORS FOR ITS CHROMIUM-BASED PROCESSES. WITHOUT CHROMIUM, IMO DOES NOT VIOLATE THE CATEGORICAL PRETREATMENT STANDARDS. THE VIOLATIONS OCCURRED BETWEEN NOV. 1987 AND NOV. 1991.