Fully odourised gas has been restored throughout counties Galway and Mayo, Gas Networks Ireland (GNI) has confirmed.
GNI said that all 9,600 customers in counties Galway and Mayo can now use gas safely. It said that customers should ensure all appliances are switched off prior to turning gas supply on.
It also said it was co-operating with the Commission for Energy Regulation (CER) in its investigation into how non-odourised gas was released from the Corrib gas refinery into the mains system in the west.
Customers in counties Galway and Mayo were advised to shut down supplies on Thursday until further notice for safety reasons, and the State’s national gas emergency plan was invoked, following the release.
Separate inquiries by the CER and the Environmental Protection Agency are under way, while Shell E&P Ireland has also confirmed it is undertaking an internal investigation into the incident.
A 15m flame was visible as flaring of the odourless gas to remove it from the system took place at the refinery in north Co Mayo.
Rossport resident Mary Corduff said the flaring was "constant, high pressure" with noise like a "jet aircraft".
“Once again the community bears the brunt of very intense flaring, which is a form of atmospheric pollution,” she said.
It is estimated that up to €400,000 worth of fuel – equivalent to one-fifth of the national daily demand – had to be pushed back through the system and burned off at the refinery. EPA inspectors were on site on Friday and flaring stopped on Friday night.
Natural gas is odour-free when extracted, and a chemical including sulphur is normally added at refining stage to allow leaks to be detected.
Minister for Energy Denis Naughten said he supported a call by Minister for Rural and Community Development Michael Ring for a thorough inquiry into what happened.
A spokeswoman for Mr Naughten said he would receive a report early next week from the CER, and was receiving regular reports from the gas emergency response team, which had met on a number of occasions over the past two days.
The emergency response team is part of the national gas emergency plans, established under the Gas (Interim) (Regulation) Act, 2002, and comprises representatives from Mr Naughten's department, the CER, GNI and Eirgrid.
Mr Naughten’s spokeswoman said there were no security supply issues.
Mr Ring said that answers were required “without delay”.
Mr Ring, who had supported calls for a refinery offshore as a Mayo TD, said that “we were given guarantees that this type of thing couldn’t happen”.
“Companies that sell potentially dangerous energy products to our consumers have an obligation to ensure that there is no risk to the customer,” Mr Ring said. “The fact that this has not happened is of the utmost concern.”
Shell to Sea described the incident as a “fiasco” and said it “highlighted the lack of regulation and monitoring of Shell in relation to the Corrib gas project”.
Customers who suspect a gas leak or smell gas in any part of the country should always call the 24-hour emergency line on 1850-205050.