MONTANA - DAKOTA UTILITIES CO — Gas distribution — incident on 2016-11-23

Gas distribution incident in SHERIDAN, SHERIDAN County, WY. Reported cause: EXCAVATION DAMAGE. Reported consequences: 0 fatalities, 0 injuries, 466.64 NATURAL GAS released, $4,500 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: 20160127.

Operator ID: 12684.

Reported incident date: 11/23/2016 16:15.

Location detail: 1401 WEST 5TH STREET

Cause detail: EXCAVATION DAMAGE BY THIRD PARTY

Cause detail: EXCAVATION ISSUE

Cause detail: EXCAVATOR FAILED TO MAINTAIN CLEARANCE AFTER VERIFYING MARKS

Cause detail: EXCAVATION SUB-CONTRACTORS DANIELS INC. WAS EXCAVATING IN THE AREA TO CONNECT A STORM SEWER SYSTEM WITH A LARGE EXCAVATOR WHEN THEY DUG THROUGH THE LIVE 3-PHASE ELECTRICAL PRIMARY AND 3 INCH PE GAS SERVICE FEEDING THE HOSPITAL. THE RESULTING DAMAGE TO THE GAS AND ELECTRICAL SERVICES CAUSED AN ESCAPE OF GAS AND EVENTUALLY A FIRE. THE FIRE CONSUMED THE VACATED EXCAVATOR BEFORE THE FIRE COULD BE CONTROLLED BY FIRST RESPONDERS. MDU DID NOT HAVE AN INSPECTOR ON SITE AT THE TIME OF THE INCIDENT.

PHMSA trend classification: significant incident, not serious, not fire-first.

PHMSA standardized cause: EXCAVATION DAMAGE — THIRD PARTY EXCAVATION DAMAGE.

PHMSA indexed costs: $206,200 reported total cost, $102,706.987 in 1984 dollars, $252,672.753 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.