COLUMBIA GULF TRANSMISSION CO

Incident Narrative

SHORTLY AFTER 5:30 AM ON 5/10/2012 A COLUMBIA GULF TRANSMISSION EMPLOYEE RECEIVED A CALL FROM A PERSON LIVING NEAR OUR CLEMENTSVILLE COMPRESSOR STATION. THE CALL INFORMED THE EMPLOYEE THAT THE STATION WAS MAKING A NOISE. THE EMPLOYEE ARRIVED ON SITE SHORTLY AFTER 6:00 AM AND HEARD GAS VENTING. BY 6:30 THE PROBLEM HAD BEEN ISOLATED TO A MALFUNCTIONING RELIEF VALVE. A SECOND RELIEF VALVE WAS PRESENT IN THIS SECTION OF PIPING, SO THE MALFUNCTIONING VALVE WAS CLOSED. THE STATION RESUMED NORMAL OPERATIONS. BY 7:00, A QUICK REVIEW OF OPERATING PARAMETERS WAS UNDERWAY. BEFORE 7:30 IT WAS DETERMINED THAT OVER 3000 MCF OF GAS HAD LIKELY BEEN RELEASED. A CALL WAS MADE TO THE NRC BY A FEW MINUTES AFTER 8:00. LATER THAT DAY IT WAS DETERMINED THAT A CONNECTION IN THE TUBING THAT SUPPLIED SIGNAL GAS TO THE RELIEF VALVE HAD FAILED. THIS HAD CAUSED THE RELIEF VALVE TO OPEN AT A PRESSURE SIGNIFICANTLY BELOW THE MAOP. THE CONNECTION WAS REPLACED WITH A DIFFERENT STYLE CONNECTION AT THIS LOCATION AND OTHER SIMILAR LOCATIONS. NOTE ON PART A QUESTION 19A AND 19B: COMPANY PERSONNEL ACTUALLY ARRIVED ON SITE BEFORE IT WAS DETERMINED THAT AN INCIDENT HAD OCCURRED. HOWEVER THE ELECTRONIC VERSION OF THIS FORM DOES NOT SEEM TO ALLOW THAT SEQUENCE OF EVENTS TO BE INPUT. REFERENCE THE ABOVE NARRATIVE.