A power shovel punctured a 63-mm polyethylene gas pipe pressurised at 3.9 bar at 3:45 pm on a rail station parking lot under construction. The project consisted of installing curbs and adjusting the formation level prior to laying pavement. The building contractor was grading the formation level when the shovel nicked the gas pipeline.

Rail traffic was interrupted for 1 hour due to the electrical supply outage of the catenary lines. The rail station was evacuated. Nearly 1,000 people in all were evacuated and another 2,000 stranded inside idle trains. The gas line technicians were able to plug the leak remotely. Following a round of normal explosimeter measurements, the station was reopened. The administrative office responsible for the distribution pipelines made a site visit in order to conduct an inspection.

This inspection revealed that the damaged pipe had been deviated 6 months prior within the scope of a station extension project by the distribution network manager. The Declaration of Intent to carry out Works (DICT document) and its official receipt delivered to technicians assigned oversight of the pipelines reflected the situation before the deviation. It should be pointed out that the company had been absent from the worksite for several months prior, yet had not noticed that the pipeline had been deviated. It was also mentioned that despite the presence of a few remnants of a protective screen at the periphery of the emptied zone and given the type of work being performed (simple scraping of a 20 to 25-cm top layer in order to install the pavement courses), the company did not see fit to undertake manual surveys and probes to identify the new pipeline alignment, which according to regulation was supposed to be located 80 cm beneath the completed roadway. Triangulation probes and measurements conducted to determine the plane and elevation coordinates of the point where the pipe was nicked revealed that the site plan of the deviated pipeline, as provided by the distribution network manager, was erroneous in all 3 dimensions. When exposed, the damaged pipe also revealed noncompliance in the installation relative to the proximity of the other utility lines crossed.

The inspection concluded its report by underscoring the fact that this incident had focused attention on problems tied to monitoring the work of subcontractors acting on behalf of gas utility services. The phases of drawing up project plans and updating the resulting maps were also deemed inadequate. Inspectors moreover suggested the addition of a phase with a formalised handover of the project to be scheduled in the case of a complex jobsite capable of leading to an elevation modification. The project architect for this job would be assigned to accept the new facility, which entails the responsibility of ensuring that the finished project is fully compliant with initial plans and moreover verifying that the various subcontractors working onsite are heeding the applicable comp