A natural gas leak was detected around 9 a.m. on a manifold on the network of an underground natural gas storage site in a aquifer. An on-call technician confirmed the leak by manual measurement. At 11:00 a.m., the manifold was secured and depressurised. The line and the dehydration tower connected to it were out of service.

A private company upgraded the pipe that was likely to leak, at a low point purge connection. The timbering, securing of the excavation works and stripping of the branch connection ended on 21/07. After conducting the air pressure tests on the section, the technicians noted that the leak was located further down on the DN 50 purge line in an area that had not been excavated. Further excavation works were undertaken until 28/07. This time the leak was located, at 2 m from the branch connection, with a 2.5 mm hole on the lower generatrix.

Measurements over the entire purge line indicated that the minimum thickness, except in the immediate vicinity of the borehole, was greater than that prescribed in the design. In addition, altitude measurements indicated that the slope of the purge pipe did not comply with the design.

The operator planned to temporarily repair the pipeline in late September, with a curved bottom as close as possible to the low point of the pipeline and then to permanently repair the pipeline in the summer of 2015. A similar event had already occurred in 2012 (ARIA 42398).