ENBRIDGE PIPELINES (OZARK) L.L.C.

Incident Narrative

ON JANUARY 9 AT APPROXIMATELY 8:15 AM CST, A MAINTENANCE TECHNICIAN OBSERVED OIL ON TOP OF WATER IN AN EXCAVATION AND BLACK OILY SOIL AROUND THE MANIFOLD 202 (OZARK BOOSTER MANIFOLD) AREA. THE INITIAL VOLUME OUT WAS ESTIMATED AT 4 BARRELS. IT WAS THOUGHT THAT THE SOURCE OF THE RELEASE WAS A 4"" SUMP REINJECTION LINE THAT RUNS THROUGH THE AREA. THE SUMP PUMP WAS LOCKED OUT AND CLEAN UP BEGAN, INCLUDING EXCAVATION OF THE 4"" REINJECTION LINE. THE LINE WAS EXPOSED AND THERE WERE NO SIGNS OF A LEAK. AFTER EXCAVATING PRIMARY AND SECONDARY SITE LOCATIONS ALONG WITH A SERIES OF POT HOLES, THE INITIAL INVESTIGATIVE ASSESSMENTS WERE INDICATING A POTENTIAL HISTORIC LEAK SITE SINCE VISUAL INSPECTIONS WERE NOT FINDING ANY PROBLEMS. THE VOLUME OUT ESTIMATE WAS REVISED TO APPROXIMATELY 1 BARREL. ON JANUARY 16, AN OPERATION TECHNICIAN MONITORING THE AREA NOTICED A DRIP COMING FROM THE BOTTOM OF THE DEAD LEG PIPING ON THE SUCTION SIDE OF THE BOOSTERS. THE TECHNICIAN NOTIFIED THE CONTROL CENTER TO SHUT DOWN LINE 51. FURTHER INVESTIGATION WAS CONDUCTED AND A SMALL PINHOLE LEAK WAS LOCATED COMING FROM THE DEAD LEG PIPING. NDE RESULTS INDICATED WALL LOSS ON THE PIPE SURROUNDING THE PINHOLE. A LARGER FABRICATION WAS NEEDED TO REPLACE THE PIPING AND FITTINGS CONSISTING OF A TEE AND 3 FLANGES THAT WERE WELDED AND HYDRO TESTED. A 4TH FLANGE WAS FIELD WELDED TO THE EXISTING PIPE AS THE TIE POINT FOR THE NEW FABRICATION TO THE EXISTING FACILITIES. ON JANUARY 18, THE REPLACEMENT FABRICATION WAS COMPLETED AND THE HYDRO TEST WAS SUCCESSFUL. LINE 51 WAS RESTARTED ON JANUARY 19. A METALLURGIC ANALYSIS WAS CONDUCTED ON THE DEAD LEG PIPING. THE CONCLUSION IS THE MANIFOLD 202 PIPING FAILED BY THE MECHANISM OF UNDER-DEPOSIT CORROSION DUE TO EXTENDED PERIODS OF STAGNANT CRUDE OIL IN THE SYSTEM.