ALLIANT ENERGY - INTERSTATE POWER AND LIGHT COMPANY

Incident Narrative

ON MARCH 9, 2019 AT 13:10, ALLIANT ENERGY - INTERSTATE POWER & LIGHT (IPL) RECEIVED A CALL FROM A CUSTOMER AT 401 W. VAN WEISS BLVD IN WEST BURLINGTON, IOWA STATING SHE HAD SOME WORK DONE AROUND HER HOUSE AND A CLUMP OF DIRT FELL ON HER GAS METER AND SHE COULD SMELL AND HEAR NATURAL GAS LEAKING. THE CUSTOMER WAS INSTRUCTED TO EVACUATE THE HOUSE. IPL DISPATCHED A SERVICE MECHANIC, WHO ARRIVED ONSITE AT 13:26 TO FIND THE GAS HAD IGNITED. HE IMMEDIATELY REQUESTED ADDITIONAL GAS PERSONNEL FOR ASSISTANCE. POLICE WERE ALREADY ONSITE AND THE FIRE DEPARTMENT ARRIVED SHORTLY AFTER AND SPRAYED WATER ON THE SIDE OF THE HOUSE TO MINIMIZE DAMAGE UNTIL THE GAS COULD BE SHUT OFF. DUE TO THE FROZEN GROUND, HAND DIGGING TO EXPOSE THE SERVICE LINE WAS DIFFICULT. AFTER TWO ADDITIONAL IPL EMPLOYEES ARRIVED WITH A MINI-EXCAVATOR, THE 3/4 INCH STEEL SERVICE LINE WAS EXPOSED AND SQUEEZED OFF AT APPROXIMATELY 14:50, ALLOWING FIREFIGHTERS TO EXTINGUISH THE FIRE. SHORTLY AFTER, THE SERVICE LINE WAS EXPOSED AT THE SERVICE TEE AND WAS CUT OFF AND CAPPED. A BASEMENT CONTRACTOR HAD BEEN PERFORMING EXTERIOR BASEMENT WALL REPAIR WORK AROUND THE PERIMETER OF THE HOUSE AND HAD EXPOSED THE STEEL SERVICE LINE ALONG THE EAST SIDE OF THE HOUSE. IPL IS UNAWARE WHETHER THE CONTRACTOR PROVIDED ANY SUPPORT TO THE EXPOSED SERVICE LINE IN THE EXCAVATION. THERE WAS NO ACTIVE WORK BEING PERFORMED BY THE CONTRACTOR AT THE TIME OF THE INCIDENT. THE TRENCH WALL COLLAPSED ONTO THE SERVICE LINE AND RISER, CAUSING THE THREADS ON THE 3/4 INCH NIPPLE AT THE INLET TO THE SERVICE REGULATOR TO BREAK OFF COMPLETELY. THIS ALLOWED GAS OPERATING AT 55 PSIG TO ESCAPE ALONG THE OUTER BASEMENT WALL. THE GAS WAS IGNITED BY AN UNKNOWN SOURCE, POSSIBLY STATIC OR BY ROCKS BEING BLOWN AROUND BY THE FORCE OF THE GAS. THE INCIDENT WAS NOT IMMEDIATELY REPORTED ON MARCH 9, 2019, AS INITIAL DAMAGE ESTIMATES INDICATED THE DAMAGES WOULD BE LESS THAN $50,000. UPON SEEING REVISED DAMAGE ESTIMATES, THE INCIDENT WAS CALLED INTO THE NATIONAL RESPONSE CENTER ON MARCH 11, 2019. ORIGINAL NRC REPORT NUMBER: 1239797 REVISED NRC REPORT NUMBER: 1239801 (TO MAKE CORRECTION TO AN INCORRECT DATE) 48 HOUR NRC UPDATE NUMBER: 1239986 UPDATE (04/17/2020): -NEW SERVICE LINE TO HOUSE INSTALLED ON 07/22/2019 -REPORT CHANGED TO FINAL.