The pipeline section was isolated between Waikanae and Pauatahanui, before the pipeline between both locations was depressurised.
"Depressurising the section will enable our engineers to take apart the valve and discover what caused the fault."
The affected pipeline section was isolated by 2.30pm with pipeline depressurisation fully completed at 5.20pm.
"While there was no immediate risk to the public, First Gas chose to err on the side of caution."
He apologised for the traffic delays.
"As soon as the incident occurred, our repair crews worked very efficiently to isolate the faulty valve so traffic flows could return to normal before peak hour traffic started.
"We'd like to thank the professional traffic management and incident co-ordination by the Fire Service crews from Paekakariki, Paraparaumu, and Porirua, as well as the Wellington district police team.
"We thank everyone for their patience while we resolved the incident."
He said the gas leak isolation at the Paekakariki North Mainline Valve Station didn't result in any loss of gas supplies to the Wellington region.
"During the incident the First Gas land owner communication team were contacting all landowners in the near vicinity of the incident to alert and update them on the situation."
While this section of the high pressure gas transmission system is out of service, First Gas will be taking the opportunity to conduct other maintenance more easily done when the pipeline is not under pressure.
"This means residents in the area may see more activity by us between Waikanae and Pauautahanui over the next week or so.
"We do not expect any of our works to cause further disruption to the public."
