ROCKY MOUNTAIN NATURAL GAS LLC — Gas transmission and gathering — incident on 2019-04-07

Gas transmission and gathering incident in Not Within a Municipality, PITKIN County, CO. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 800 NATURAL GAS released, $842,480 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: 20190056.

Operator ID: 17620.

Reported incident date: 4/7/2019 9:00.

Location detail: WC71 PROCESS

Cause detail: THREADED CONNECTION/COUPLING FAILURE

Cause detail: 4/6/19 AT 10:30PM MT- DENVER GAS CONTOL RECEIVED A CHAIN OF ALARMS RESULTING IN AN EMEGENCY SHUT DOWN AND ISOLATION OF THE WOLF CREEK WELL #71. ON-CALL OPERATIONS PERSONNEL WERE NOTIFIED AND DISPATCHED TO THE SITE. GAS CONTROL UTILIZED AUTOMATIC ISOLATION VALVES AND SHUT IN THE ENTIRE STORAGE FIELD. COMPANY PERSONNEL SHUT MANUAL ISOLATION VALVES ALONG 3-INCH PIPELINE WHILE TRAVELING TO THE WELL LOCATION. UPON ARRIVAL (1:00 AM MT ON 4-7-19) TO WELL LOCATION COMPANY PERSONNEL OBSERVED A SMALL FIRE BURING FROM 1-INCH GLYCOL PIPING OFF OF THE GAS/GLYCOL HEAT EXCHANGER ON THE DEHYDRATION UNIT HOUSE WITHIN THE PROCESS BUILDING. A SMALL FIRE WAS OBSERVED FROM RESIDUAL GAS BURNING OFF FROM PROCESS PLUMBING. PERSONNEL ALSO WITNESSED EVIDENCE OF SMALL SECONDARY FIRES INSIDE THE PROCESS BUILDING THAT WERE STILL SMOLDERING. ALL TRIETHYLENE GLYCOL WAS CONTAINED WITHIN THE SECONDARY CONTAINMENT OF THE PROCESS BUILDING OR WAS CONSUMED DURING THE FIRE. PERSONNEL LEFT THE WELL SITE AND EVALUATED ALL OTHER WELL LOCATIONS WITHIN THE STORAGE FIELD. NO ISSUES WERE OBSERVED AT ANY OTHER LOCATIONS. PERSONNEL RETURNED BACK TO WELL #71 LOCATION TO EVALUATE OVERALL SITE CONDITIONS. THEY VERIFIED SLAM VALVES, VENT VALVE AND SUB-SURFACE SAFETY VALVE WERE IN THE CORRECT EMERGENCY SHUT POSITION AND ISOLATED MANUAL BLOCK VALVES ON THE FLOW LINE AND PIPELINE. PERSONNEL EVALUATED WELLHEAD HOUSED IN WELLHEAD BUILDING; NO ISSUES WERE OBSERVED, SHUT MASTER AND WING VALVES ON TREE ALL OK. COMPANY PERSONNEL LEFT SITE TO COMMUNICATE FINDINGS WITH MANAGEMENT. MANGEMENT WAS NOTIFIED AT 6:30 AM MT (4-7-19) OF SITE FINDINGS. NO INJURIES OCCURED DURING INCIDENT. NO BREACH OF SECONDARY CONTAINMENT OF ANY STORED OR RELEASED LIGUIDS (TRIETHYLENE GLYCOL). FOLLOW-UP 48 HOUR NRC #1242266. THROUGH INTERNAL AND EXTERNAL INVESTIGATION THE ROOT CAUSE WAS CAUSED BY A FAILED 1-INCH NIPPLE ON GLYCOL GAS HEAT EXCHANGER ON THE DEHYDRATION UNIT. IGNITION SOURCE WAS DETERMINED TO BE UNKNOWN AT THE TIME OF THE INCIDENT. IT IS KNOWN THAT THE PROCESS BUILDING CONTAINED AN ATOMIZED GLYCOL AND GAS MIXTURE RESULTING IN A EXPLOSION AND FIRE. LESSONS LEARNED: OPERATOR IS USING INTERNAL AND EXTERNAL ENGINEERING TO REVIEW THE USE OF HIGH PRESSURE THREADED CONNECTIONS ON AUXILIARY LINES ON DEHYDRATION UNITS.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — THREADED CONNECTION/COUPLING FAILURE.

PHMSA indexed costs: $844,980 reported total cost, $395,917.593 in 1984 dollars, $975,023.181 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.