SUMMIT MIDSTREAM PARTNERS, LLC

Incident Narrative

ON MAY 8, 2016 AT 9:10 AM THE SUMMIT MIDSTREAM CONTROL CENTER WAS NOTIFIED BY A THIRD PARTY TRANSPORT DRIVER, THAT THE SUMMIT 400 BARREL STAMPEDE SURGE RELIEF TANK HAD OVERFILLED. SUMMIT IMMEDIATELY DISPATCHED A PIPELINE TECHNICIAN TO THE SITE. THE TECHNICIAN ARRIVED AT THE SITE AT APPROXIMATELY 10:30AM AND CONFIRMED THAT THE SURGE RELIEF TANK FOR THE STAMPEDE PIPELINE HAD OVERFILLED. UPON COMPLETION OF AN INTERNAL INVESTIGATION, IT WAS DETERMINED THAT THE TUBING COUPLING FOR NITROGEN SUPPLY TO THE SURGE RELIEF VALVE LEAKED CAUSING THE NITROGEN BOTTLE PRESSURE TO DRAIN DOWN. THIS CAUSED THE SURGE VALVE TO FAIL OPEN TO THE SURGE RELIEF TANK. AT THE TIME OF THE INCIDENT, THE PIPELINE WAS NOT FLOWING AND HAD NO SCHEDULED DELIVERIES. AFTER THE LAST SCHEDULED DELIVERY ON MARCH 23, 2016 WAS COMPLETE, THE PIPELINE WAS SHUT DOWN AND WAS PACKED WITH APPROXIMATELY 100 PSIG OF PRESSURE. THE RESIDUAL PRESSURE FROM THE 47 MILE PIPELINE DRAINED INTO THE STAMPEDE SURGE RELIEF TANK CAUSING IT TO OVERFILL AND SPILL 31 BARRELS OF CRUDE OIL. ALL PRODUCT WAS CONTAINED IN THE GLOBAL TANK FARM TANK BATTERY CONTAINMENT AREA AND HAS SINCE BEEN REMEDIATED. APPROXIMATELY 850 TONS OF IMPACTED SOIL WAS REMEDIATED. A SUPPLEMENTAL REPORT WAS FILED ON SEPTEMBER 20, 2016 TO PROVIDE MORE PRECISE GPS COORDINATES OF THE TANK, PROVIDE AN UPDATED FINAL ENVIRONMENTAL REMEDIATION COST, AND TO INCLUDE THE AMOUNT OF IMPACTED SOIL REMEDIATED.