DOMINION ENERGY TRANSMISSION, INC.

Incident Narrative

ON 9/5/2018, A CONTRACTOR WORKING FOR DETI WAS MOWING THE G-134 RIGHT-OF-WAY WITH A BRUSH HOG MOUNTED ON THE FRONT OF A SKID STEER. AT 12:55 PM, THE CONTRACTOR FELT THE BRUSH HOG HIT AN OBJECT AND A PROPANE CLOUD BEGAN TO FORM AROUND THE SKID STEER AND BRUSH HOG. THE CONTRACTOR IMMEDIATELY PRESSED THE SKID STEER ENGINE SHUTOFF SWITCH, BUT THE SKID STEER ENGINE DID NOT SHUTOFF DUE TO THE PROPANE CLOUD. THE CONTRACTOR THEN PUT THE SKID STEER IN REVERSE AND BACKED OUT OF THE PROPANE CLOUD UNTIL THE SKID STEER ENGINE DID SHUTOFF. THE CONTRACTOR CONTACTED DETI PERSONNEL AT THE HASTINGS EXTRACTION PLANT AND COMMUNICATED THE SITUATION. AT 12:57 PM, DETI PERSONNEL STARTED TO ISOLATE G-134. THE CPM LEAK DETECTION SYSTEM HAD ALREADY CLOSED THE UPSTREAM VALVE ON G-134. DETI PERSONNEL WERE MOBILIZED TO LOWER RUN GATE TO CLOSE THE DOWNSTREAM VALVE ON G-134. AT 1:04 PM, DETI PERSONNEL CLOSED THE DOWNSTREAM VALVE ON G-134 AT LOWER RUN GATE. AT 1:08 PM, G-134 WAS ISOLATED. AT 1:09 PM, EMERGENCY TRAFFIC LIGHTS WERE ACTIVATED TO RESTRICT TRAFFIC ON ROUTE 20 NEAR THE HASTINGS EXTRACTION PLANT. DETI PERSONNEL STARTED TO MONITOR THE LOWER EXPLOSIVE LIMIT FOR PROPANE IN THE AREA SURROUNDING THE LEAK WITH COMBUSTIBLE GAS INDICATORS. AT 1:33 PM, FLARING OF PROPANE FROM G-134 STARTED AT LOWER RUN GATE. AT 4:15 PM, VENTING OF PROPANE TO THE RELIEF VALVE HEADER INITIATED AT THE HASTINGS EXTRACTION PLANT. AT 4:20 PM, DETI PERSONNEL DETERMINED THAT IT WAS SAFE TO APPROACH THE SITE OF THE LEAK BASED ON THE MONITORING OF THE LOWER EXPLOSIVE LIMIT FOR PROPANE. AT 5:40 PM, DETI PERSONNEL LOCATED AND CLOSED A 1"" DIAMETER VALVE ON G-134 AT THE SITE OF THE LEAK. THE 1"" DIAMETER VALVE WAS PART OF A TAP ON G-134 THAT CONSISTED OF A 16"" LONG NIPPLE AND A SECOND 1"" DIAMETER VALVE THAT WAS PREVIOUSLY CLOSED AND PLUGGED. THE TAP ON G-134 WAS IDENTIFIED AS THE SOURCE OF THE LEAK AND WAS PARTIALLY EXPOSED ABOVEGROUND. THE CONTRACTOR WORKING FOR DETI HAD CONTACTED THE TAP ON G-134 WITH THE BRUSH HOG WHICH CAUSED THE 16"" LONG NIPPLE TO BREAK RIGHT AT THE TOP OF THE 1"" DIAMETER VALVE ON G-134. DETI PERSONNEL ALSO LOCATED A SHORT PIECE OF CASING PIPE THAT HAD BEEN INSTALLED AROUND THE TAP ON G-134. AT 5:48 PM, DETI PERSONNEL DETERMINED THAT IT WAS SAFE TO TURN OFF THE EMERGENCY TRAFFIC LIGHTS AND ALLOW TRAFFIC ON ROUTE 20 NEAR THE HASTINGS EXTRACTION PLANT. AT 9:55 PM, FLARING OF PROPANE FROM G-134 WAS STOPPED AT LOWER RUN GATE. ON 9/6/2018, DETI PERSONNEL AND CONTRACTORS WORKING FOR DETI EXCAVATED THE TAP ON G-134 AND COMPLETED REPAIRS. THE REPAIRS CONSISTED OF REMOVING THE TWO 1"" DIAMETER VALVES AND THE 16"" LONG NIPPLE, THREADING A PLUG INTO THE REMAINING THREADOLET ON G-134, BACKWELDING THE PLUG, AND APPLYING COATING TO THE PLUG. COATING WAS ALSO APPLIED TO G-134 ON A SHORT SECTION OF 4"" DIAMETER PIPE FOR WHICH COATING HAD BEEN REMOVED TO FACILITATE THE REPAIRS. G-134 WAS PLACED BACK INTO SERVICE ON 9/6/2018 AT 7:00 PM.