Abstract: ON NOVEMBER 12, 1985, AT APPROXIMATELY 2 PM, EMPLOYEE #1, A REFINING PLANT OPERATOR, AND EMPLOYEE #2, AN APPRENTICE, WERE ATTEMPTING TO LOCATE THE CAUSE OF OVERPRESSURE AND LEAKING IN A HYDROGEN SULFIDE STRIPPING TOWER. THEY WERE WORKING VERY NEAR AN ENCLOSED 3 FOOT BY 3 FOOT BY 3 FOOT SIZE SEWER VAULT. THE VAULT WAS EQUIPPED WITH A 6 INCH DRAIN. HOT WATER AND STEAM WERE DISCHARGED INTO THE VAULT, CAUSING IT TO FILL BEYOND CAPACITY AND CAUSE AN OVERPRESSURE. THE SEWER VAULT RUPTURED, CAUSING THE VIOLENT DISCHARGE OF HOT WATER, STEAM AND CHUNKS OF OVERBURDEN. BOTH EMPLOYEES WERE STRUCK BY THE DISCHARGING MATERIAL. THEY SUFFERED EXTENSIVE SEVERE BURNS AND FRACTURES. BOTH EMPLOYEES SPENT WEEKS IN THE HOSPITAL AND FACE MONTHS OF RECOVERY AND REHABILITATION. THE CAUSE OF THE OVERPRESSURE AND RELEASE IS NOT POSITIVELY KNOWN AND MAY NOT SOON BE DISCOVERED. NO EVIDENCE OF A VIOLATION HAS BEEN FOUND.