City bore on way to being shut off

Council contractors work to contain a geothermal bore in the Rotorua city centre.

Work has continued today to shut down an old bore which burst into life in a service lane in Rotorua's central city during the weekend.

The bore has been spraying water, steam, dirt and gravel up to two storeys high and has been fenced off to ensure public safety while work to shut it down is undertaken.

The area around the hole which was created when the bore, situated behind Vetro, blew its top on Sunday afternoon, has been dug up to expose the bore's outer casing.

Cold water will continue to be pumped into it to quench it so that it can be regrouted and shut down. The grouting is a fine cement which will be poured over the bore and will also help fill any cavities in the ground.

All going well this afternoon, the bore will be fully quenched by the end of today and will be grouted tomorrow .

Businesses in the area have continued to operate while the work on the bore has occurred.

Once the bore has been regrouted, Rotorua Lakes Council will arrange for the service lane to be reinstated and the site - including surrounding buildings which have been sprayed with dirt and gravel - to be cleaned up.

The council deals with bore blowouts about twice a year and council geothermal inspector Peter Brownbridge said this latest one may have happened due to a sudden drop in the barometer.

The unused bore was a low pressure bore and in the cold weather the blowout on Sunday created a lot of steam over the top of nearby buildings, attracting onlookers.

"Dealing with bore blowouts is part and parcel of living in Rotorua, part of what makes this city so 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."

When blowouts occur the bores need to be stabilised before work to shut them down can be carried out. This involves forcing cost water down into the bore to quench it.

Council staff and contractors were on site shortly after being called to the blowout by the Fire Service about 2.30pm on Sunday.

Police cordoned off the area for public safety and a fence was erected yesterday. Security guards have been posted at the site after hours to ensure public safety.