PIPELINE Accident Report

Natural Gas Pipeline Rupture And Subsequent Explosion
St. Cloud, Minnesota
December 11, 1998

NTSB Number: PAR-00-01
NTIS Number: PB2000-916501

Executive Summary

About 10:50 a.m. on December 11, 1998, while attempting to install a utility pole support anchor in a city sidewalk in St. Cloud, Minnesota, a communications network installation crew struck and ruptured an underground, 1-inch-diameter, high-pressure plastic gas service pipeline, thereby precipitating a natural gas leak. About 39 minutes later, while utility workers and emergency response personnel were taking preliminary precautions and assessing the situation, an explosion occurred. As a result of the explosion, 4 persons were fatally injured; 1 person was seriously injured; and 10 persons, including 2 firefighters and 1 police officer, received minor injuries. Six buildings were destroyed. Damage assessments estimated property losses at $399,000.

Probable Cause

The National Transportation Safety Board determines that the probable cause of this accident was the lack of adequate procedures by Cable Contructors, Inc., to prevent damage to nearby utilities when its anchor installation crews encountered unusual conditions such as striking an underground obstacle. Contributing to the severity of the accident was the delay by Cable Contructors, Inc., in notifying the proper authorities.

The major safety issues identified in this investigation are the adequacy of the safety and emergency procedures used by Cable Constructors, Inc., crews when working in the vicinity of underground facilities and the adequacy of St. Cloud Fire Department procedures and training for responding to natural gas leaks.

As a result of its investigation of this accident, the Safety Board makes safety recommendations to the Research and Special Programs Administration, the Occupational Safety and Health Administration, the Associated General Contractors of America, the National Utility Contractors Association, the Power and Communications Contractors Association, the National Cable Television Association, the American Public Works Association, and the International Association of Fire Chiefs.