DTE GAS COMPANY

Incident Narrative

9/12/21 GROUND HEAVE 10015 WEST FORT & DEARBORN STREET: GROUND HEAVE IMPACTED THE FOLLOWING UTILITIES: GREAT LAKES WATER AUTHORITY (GLWA), ATT, COMCAST, DTE ELECTRIC, AND DTE GAS (6-INCH CI 2 PSI, 16-INCH CI 10PSI, 24-INCH STEEL 145PSI). THE INVESTIGATION IS ONGOING WITH A UNIFORMED ICS (CITY OF DETROIT, MDOT, GLWA, DTE GAS) AND NO CAUSE HAS BEEN DETERMINED YET. A SUPPLEMENTAL REPORT WILL BE FILED WITH MORE DETAILS AND FOLLOW-UP OF THIS EVENT. 1/24/2022 UPDATE ON THE INCIDENT CAUSE: ON SEPTEMBER 11, 2021, SIGNIFICANT, UNEXPECTED GROUND MOVEMENT RESULTED IN TWO MAJOR HEAVE AREAS AND DAMAGE TO EXISTING BUILDINGS, PAVEMENT, AND UTILITY STRUCTURES INCLUDING DTE GAS INFRASTRUCTURE AT/NEAR THE INTERSECTION OF FORT STREET AND DEARBORN STREET IN DETROIT, MICHIGAN. INVESTIGATIONS THUS FAR CONFIRM THE GROUND FAILURE OCCURRED DUE TO A RELATIVELY RAPID LOADING OF A LAYER OF SOFT CLAYS BETWEEN 25 AND 40 FT BELOW THE GROUND SURFACE. DTE UNDERSTANDS THAT THE RELATIVELY RAPID LOADING WAS CAUSED BY THE INCREASE IN HEIGHT AND WEIGHT OF A MILL SCALE STOCKPILE AT THE FORT IRON AND METAL FACILITY. THE GROUND FAILURE OCCURRED CONCENTRICALLY AROUND THE LARGE STOCKPILE OF MATERIAL LOCATED AT THE PROPERTY, A METAL SCRAP YARD OWNED AND OPERATED BY FORT IRON & METAL COMPANY. ON INFORMATION AND BELIEF, THE MILL SCALE MATERIAL WAS STOCKPILED TO SOME DEGREE AT THIS LOCATION BY FORT SINCE AT LEAST MAY 2019.