100 Whanganui properties still without gas as water removed from pipes

GasNet contractors have been working from 7am until 9pm every day since the gas outage occurred. Photo / Bevan Conley

A high pressure jet of water is responsible for the loss of gas supply to central Whanganui properties.

Since Sunday, February 9, GasNet has been working to restore gas supplies to 282 properties but has faced several setbacks.

About 100 properties are still without gas.

The saga began when a leak in a Whanganui District Council water pipe, running alongside a main GasNet pipe on St John's Hill, created a jet of water that hit the gas pipe at high pressure.

The pressure of the water created a hole in the GasNet pipe and began filling it with water and surrounding dirt, GasNet general manager Geoff Evans said.

It is not known how long the water pipe had been leaking, but the council repaired the leak and water stopped entering the network around 10.30am on February 9.

Evans said water had filled up some of the main pipes in the St John's Hill area, then flooded the London St pipes and into the College Estate area, central streets and Aramoho.

He estimated 7,000 litres of water had flowed into the network.

"The real problem was to first to identify the extent and then we sent our technicians out to see who had gas and who didn't. We managed to get the extent of it pretty quickly on Sunday and then we had to deal with how to best approach it and we decided we needed a reliable supply."

The GasNet district regulator station in Liverpool St was able to provide a stable and reliable gas supply once the water had been removed. However, it had not been possible to get a reliable gas supply source at the College Estate and Aramoho ends to recommission supplies.

Evans said no suburb had been a priority and the Liverpool St station was a logical point to begin work.

Technicians spent all of last Tuesday removing water from pipes in College Estate and by Friday morning all supplies in College Estate and St John's Hill had been recommissioned.

Evans said he understood consumers' frustration about the ongoing outage.

"People can expect it to be a number of days. It hasn't changed but at some stage it will come down to tomorrow or today.

"If we just cross our fingers and blow air through the pipes and hope it's clear we know from experience it doesn't work. We've got to get the water out with a high degree of confidence otherwise people end up losing their gas supply again later."

For every section of pipe where water needs to be cleared, a hole is dug at every intersection and corner.

The GasNet pipe was situated alongside a leaking Whanganui District Council water pipe that punctured the side of the gas pipe and filled it with water and sand. Photo / Lucy Drake

The meter for every property in the section is then turned off and water is removed from the main pipe by blowing it down with a foam swab shaped like a bullet.

Once it is clear, water is blown out of the service pipes that connect the meters to the main pipe and back into the main pipe. Any remaining water is then flushed from the main pipe.

Evans said delays could be caused when the foam air compressor hit large stones or sand that entered because of the leaking water pipe.

Water removal in London St was completed, with 900m of pipe cleared and about 4000 litres of water removed. London St from Campbell St to Halswell St and Pitt Street were commissioned on Sunday.

Water has been removed from pipes in Argyle, Barrack, Tay, Gloucester and Russell streets. Spier St is partially complete and removal has begun on Glasgow St and Somme Pde.

Evans said when gas was reintroduced to a street a GasNet representative would visit each affected property to check the meter and the consumer's appliances for any faults.

Consumers in College Estate and St John's Hill should contact GasNet for assistance if their supply is not working.

Anyone affected by the outage is able to use the Splash Centre shower facilities for free while their supply is affected. They should take some form of address confirmation with them.