A report by the Commission for the Regulation of Utilities has found that an IT problem at the Corrib Gas Terminal in Mayo last year caused odourless gas to be released into the network.
Without the distinctive foul odour, which is injected into natural gas at the Terminal, it would be impossible for gas users to tell if there was a leak.
Up to 10,000 customers in Galway and Mayo were instructed to turn off their gas last September when the incident occurred for safety’s sake.
The report states that on the morning of September 21, 2017 the Bellanaboy Bridge Gas Terminal was restarting after a planned shutdown for IT upgrades.
However the upgrades caused the odour injection systems to default to an inactive mode during the reboot, leading to odourless gas being sent out from the terminal into the network
The problem was detected by 02:30 that morning and the National Gas Emergency Plan was activated at 07:00.
All of the odourless gas was directed back to the Terminal and burned off.
While there was no additional risk of a gas leak because of the incident, some 10,000 customers in Galway and Mayo were directed to turn off their gas.
No fines were levied on Shell E&P Ireland by the CRU for the incident, but “enforcement actions” were taken against them and Gas Networks Ireland after the investigation concluded.
The report notes that, “The operating procedure covering the start-up process did not include a step requiring the operator to reset the odourant system to inject odourant.”
As a result of the incident the CRU directed Shell E&P Ireland to submit a plan for addressing “deficiencies in their operating procedures” that caused the incident.
The CRU is responsible for the safety regulation of natural gas transmission and distribution, and the regulation of entities with a licence for the production of natural gas or other petroleum products.