Bore blowout sees action plan begin (+video)

A bore eruption in the Rotorua city centre is not being linked to a change in the geothermal field, according to the Rotorua Lakes Council.

Water and gravel shot 15m into the air on Sunday from a bore in a service lane between Amohau and Eruera streets. Council geothermal inspector Peter Brownbridge said the bore was drilled in 1974 but it was not known when it was abandoned.

"The focus is on getting a water flow down into the bore it will die down and we can get into it to re-grout and close it off."

A digger was at the scene to clear the area around the bore so workers could see what they were working with.

"We've established we are dealing with a bore, rather than a bore feeder pipe, which will be much easier to fix," Mr Brownbridge said.

The council dealt with bore blowouts about twice a year and this one may have happened due to a sudden drop in the barometric pressure (external air pressure), he said.

The unused bore was a low-pressure bore and in the cold weather the blowout appeared more spectacular than it actually was, creating a lot of steam over the top of nearby buildings and attracting onlookers.

"Dealing with bore blowouts is part and parcel of living in Rotorua, part of what makes this city unique," Mr Brownbridge said.

"There's no reason to believe it had anything to do with anything changing in the geothermal field.

"Rotorua is a lot safer now than just prior to the bore closures of the early 1980s."

Once the bore had been stabilised, grouting - a fine cement - would be forced into the bore under pressure to shut it down and plug any cavities in the ground, Mr Brownbridge said.

The service lane remained off-limits but businesses in the area were operating as normal yesterday.