ENABLE GAS TRANSMISSION, LLC — Gas transmission and gathering — incident on 2018-12-27

Gas transmission and gathering incident in NASHVILLE, HOWARD County, AR. Reported cause: NATURAL FORCE DAMAGE. Reported consequences: 0 fatalities, 0 injuries, 200 NATURAL GAS released, $167,000 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20190007.

Operator ID: 602.

Reported incident date: 12/27/2018 8:00.

Location detail: ROAD CROSSING

Cause detail: LIGHTNING

Cause detail: ON 12-27-2018, A NATURAL GAS LEAK WAS REPORTED ON ENABLE GAS TRANSMISSION LINE AM-165. THE LEAK WAS REPORTED TO BE COMING FROM A CASING VENT ON MOUNT PLEASANT DRIVE NEAR NASHVILLE, AR IN HOWARD COUNTY. THE PIPELINE WAS EXCAVATED ON BOTH SIDES OF THE ROAD AND NO SOLUTIONS FOR REPAIR WERE FOUND AS THE LEAK APPEARED TO BE INSIDE THE CASING. PLANS WERE INITIATED TO COMPLETE A BORE ACROSS THE ROAD AND TIE IN WITH STOPPLE FITTINGS. THE ROAD WAS CLOSED AND MANNED DURING THE REPAIR EFFORTS. THE BORE AND TIE-IN WERE COMPLETED ON 12-29-2018. UPON COMPLETION OF THE CONSTRUCTION, PIPING WAS REMOVED FROM THE CASING AND EXAMINED TO DETERMINE A CAUSE OF THE LEAK. THE CASING AND PIPE HISTORY WERE EVALUATED AND DID NOT HAVE A HISTORY OF BEING SHORTED AND THE PIPELINE HAD MET THE ESTABLISHED -.850 V POLARIZED POTENTIAL CRITERIA. UPON EXAMINATION OF THE PIPE, THERE WAS EVIDENCE OF LIGHTNING DAMAGE. THIS WAS IDENTIFIED BY METAL PUDDLING AND SPLATTER AT THE SITE OF THE LEAK. THE SURROUNDING PIPELINE SYSTEM WAS EVALUATED FOR ANY ADDITIONAL EFFECTS OF THE LIGHTNING AND NO OTHER DAMAGE WAS FOUND. AN INITIAL CALL WAS PLACED TO THE NRC ON 12/27 (#1234021) AND A 48 HOUR FOLLOW UP WAS PROVIDED ON 12/29 (#1234159). DURING THE 48 HOUR FOLLOW UP 3.1 MMCF WAS PROVIDED AS THE ESTIMATED VOLUME OF COMMODITY RELEASED. THIS ESTIMATE WAS CALCULATED USING A 1/2" HOLE AT 120 PSIG FOR 96 HOURS (EXPECTED TIME FOR COMPLETION). AFTER COMPLETION OF THE NEW BORE THE OLD CARRIER PIPE AND CASING WERE REMOVED AND IT WAS DISCOVERED THAT THE SIZE OF THE HOLE TO BE 1/8". THE LENGTH OF THE TIME OF GAS LOSS WAS SHORTER THAN INITIALLIY CALCULATED (56 HOURS INSTEAD OF 96). WHEN REPLACING 1/2" WITH AN 1/8", AND 96 HOURS WITH 56 THE GAS LOSS WAS LOWERED FROM 3.1 MMCF TO 200 MCF 1/28/2019 SUPPLEMENTAL REPORT PART E. 1 CHANGED ESTIMATED PRESSURE AT THE POINT AND TIME OF THE INCIDENT FROM 400 PSIG TO 120 PSIG. PART H ADDITIONAL DETAIL AROUND GAS LOSS CALCULATION FOR INCIDENT.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: NATURAL FORCE DAMAGE — LIGHTNING.

PHMSA indexed costs: $170,834 reported total cost, $81,985.941 in 1984 dollars, $200,944.451 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.