Warren asked Enbridge to identify and mark its underground natural gas pipelines in the area involved in the reconstruction before Warren began excavation. Enbridge contracted with PUL to provide the necessary information for Warren. PUL assigned one of its employees to locate and mark Enbridge’s pipelines in the area affected by the reconstruction.
 The PUL employee assigned the task of locating and marking Enbridge’s pipelines in the area affected by the reconstruction neither identified nor marked a three-quarter inch pipeline into the commercial plaza at 3885-3891 Bloor Street West.
The AccidentRead the full decision at: Ontario (Labour) v. Enbridge Gas Distribution Inc.
 Warren’s backhoe operator inadvertently struck Enbridge’s unmarked pipeline into the plaza. The displacement dislodged the pipe from its fitting attached to the outside wall of the plaza. An unregulated flow of natural gas escaped into the basement of the plaza.
 About six to nine minutes after the pipe had become dislodged, an unknown source of ignition caused the gas to explode. The blast levelled the plaza. The force of the explosion and the ensuing fire damaged or destroyed several structures nearby. Seven people were killed, several more injured.