ENBRIDGE PIPELINES (SOUTHERN LIGHTS) L.L.C.

Incident Narrative

ON APRIL 26, 2019, WHILE COMPLETING A ROUTINE SITE VISIT, AN ODOR WAS NOTICED AT ENBRIDGE'S VALVE SITE, MP 313. FOUR GAS METER READINGS WERE NOT DETECTED, AND THERE WAS NO VISIBLE PRODUCT. A FEW DAYS LATER, PROBING IN THE AREA WAS COMPLETED, VAPORS NOT BEING DETECTED. ON MAY 4, 2019 A CONSULTANT WAS HIRED TO CONDUCT HAND AUGER SOIL BORINGS TO COLLECT SOIL AND VAPOR SAMPLES 4 FEET BELOW GRADE. GROUNDWATER WAS NOT ENCOUNTERED BUT DATA INDICATED VAPORS THAT WERE LIKELY FROM DILUENT, SUGGESTING A LINE 13 VALVE ISSUE. ON MAY 15, 2019 EXCAVATION BEGAN AT THE LINE 13 VALVE, EXPOSING THE SERVICE PIPING. ON MAY 17, 2019 A LOOSE ELBOW ON THE BODY BLEED PIPING WAS IDENTIFIED AS THE SOURCE OF THE RELEASE. A TEMPORARY REPAIR WAS MADE UNTIL A LINE 13 OUTAGE COULD BE SCHEDULED. ON JUNE 2, 2019 THE ELBOW WAS REPLACED AND THE VERTICAL PORTION OF THE SERVICE PIPING REDUCED IN LENGTH AND RETHREADED. AT THE END OF MAY 2019, A PLAN WAS DEVELOPED TO PERFORM ADDITIONAL WORK BASED ON LAB REPORTS CONFIRMING IMPACTED SOILS THAT REMAINED IN THE EXCAVATION. THIS PLAN WAS CARRIED OUT IN OCTOBER/NOVEMBER 2019, AT WHICH TIME SAMPLES EXCEEDED STATE CRITERIA. AN ADDITIONAL PLAN WAS TO EXECUTE A SOIL BORE IN MARCH 2020 AT WHICH TIME THE PROJECT WAS PUT ON HOLD DUE TO THE COVID PANDEMIC. THE SOIL BORE TOOK PLACE IN JULY 2020. THE RESULTS CONFIRMED IMPACT TO GROUNDWATER, AND PROPER NOTIFICATIONS TO THE WISCONSIN DNR WERE MADE. ENVIRONMENT WORKED WITH THEIR CONTRACTOR TO DETERMINE THE NEXT STEPS FOR REMEDIATION. ON AUGUST 25, 2020, IT WAS DETERMINED THAT THE COST FOR ADDITIONAL REMEDIATION WORK WOULD EXCEED THE $50K THRESHOLD AND REQUIRE AN NRC NOTIFICATION. THE INITIAL NRC NOTIFICATION WAS COMPLETED ON AUGUST 25, 2020 AT 1:19 PM CDT (REPORT #1285561) AND THE 48-HOUR UPDATE WAS COMPLETED ON AUGUST 27, 2020 AT 11:48 AM CDT (REPORT #1285729). CONTRACTORS WERE HIRED TO ASSIST WITH THE REMEDIATION OF THE SITE TO DEFINE THE EXTENT OF GROUNDWATER IMPACTS. TWENTY-SIX SOIL BORINGS WERE COMPLETED, AND EIGHT MONITORING WELLS WERE INSTALLED ACROSS THE SITE TO PERFORM QUARTERLY GROUNDWATER MONITORING. THE REMEDIATION WORK IS BEING COMPLETED UNDER THE GUIDANCE OF THE WDNR REMEDIATION AND REDEVELOPMENT PROGRAM. APPROXIMATELY 130.18 TONS OF CONTAMINATED SOIL AND SLURRY HAVE BEEN DISPOSED OF AT AN APPROVED LANDFILL SITE. ENBRIDGE CONSULTANTS AND CONTRACTORS COMPLETED THE SUPPLEMENTAL SITE INVESTIGATION IN DECEMBER 2021 THAT INCLUDED FURTHER SOIL SAMPLING AND ANALYSIS OF THE RELEASE AREA AND THE INSTALLATION OF REMEDIATION WELLS TO RECOVER FREE PRODUCT THAT WAS IDENTIFIED AS A RESULT OF THESE SUPPLEMENTAL SITE INVESTIGATION ACTIVITIES. BASED ON THE DATA COLLECTED, THE VOLUME OUT CALCULATION WAS REVISED TO APPROXIMATELY 189 BARRELS. THIS WAS REPORTED TO THE WDNR ON MARCH 16, 2022, AS PART OF THE SUPPLEMENTAL SITE INVESTIGATION REPORT. AN AUTOMATED PRODUCT RECOVERY SYSTEM WAS OPERATED FROM SEPTEMBER TO NOVEMBER 2021 AND WILL BE RECOMMISSIONED IN APRIL 2022. VOLUME RECOVERED TO DATE IS 29 BARRELS (12 VIA EXCAVATION AND 17 VIA PRODUCT RECOVERY). QUARTERLY GROUNDWATER MONITORING IS ON-GOING TO DETERMINE TRENDS IN GROUNDWATER CONCENTRATIONS OVER TIME AND TO ASSESS THE POTENTIAL NEED FOR FURTHER REMEDIAL ACTION. RESULTS OF THE SUPPLEMENTAL SITE INVESTIGATION SUGGEST THAT SOIL IMPACTS AND FREE PRODUCT ARE LARGELY CONSTRAINED TO A SMALL AREA BENEATH THE RELEASE SOURCE. GROUNDWATER IMPACTS EXIST PRIMARILY ON ENBRIDGE ROW AND ENBRIDGE OWNED PROPERTY, WITH SOME GROUNDWATER IMPACTS IN THE NEARBY ROAD ROW. NO POTABLE WELLS OR SURFACE WATER RECEPTORS HAVE BEEN IMPACTED BY THIS RELEASE. ENBRIDGE CONTINUES TO WORK WITH THE WDNR AND WILL BE SUBMITTING A REMEDIAL ACTIONS OPTIONS REPORT (ROAR) AND A RESPONSE ACTION PLAN (RAP) IN 2022.