Bore shut after geothermal activity in Lake Rd
Four properties that used a private bore for heating will be affected after it was grouted shut.
Rotorua Lakes Council is checking with the residents to see if they have alternative heating options and what help it can provide while they get something sorted.
The privately-owned bore was found to be the cause of the geothermal activity in a medianstrip garden on Lake Rd near Kuirau Park on Wednesday.
A volcanologist described the emergence of the fumarole — a steam-driven vent — as apparent “infrastructure failure”, while a council expert said the event was “man-made”.
It was spurting out water, steam and mud, and a section of the road was closed from Wednesday afternoon until yesterday.
The cause of the fumarole was confirmed after a nearby bore was quenched, causing water levels in the fumarole to drop significantly, the council said in a statement.
Council community and regulatory services manager Kurt Williams said the road re-opened yesterday after the activity died down overnight.
Well drillers have completed grouting the bore shut.
Williams said council staff would keep an eye on the area at the weekend to ensure everything remains settled.
The now-shut bore was privately owned but the council got involved as the issues “could impact public safety and wellbeing”.
“[The] council has worked closely with the bore owner and other technical experts to reach a suitable outcome.”
He said the grouting of the bore would impact the owner and three nearby residents who were using it for heating.
“We want to minimise disruption to those impacted by the event as much as possible, especially with the cold and wet weekend ahead of us.”
Meanwhile, drivers who drove through the geothermal activity are being “strongly advised” to clean their vehicles because of the acidic mud.
The geothermal activity has stopped, but there may still be steam visible in the area as the ground cools.
GNS volcanologist Brad Scott said the geothermal mud may be “acidic in nature” and “cleaning would be strongly advised if mud is on the vehicle”.
He said the best practice for those who drove through the area was to do a standard cold or warm-water car wash.
Scott said many vehicles in the greater Rotorua-taupo¯ area were regularly exposed to geothermal muds, “so it’s sort of business as usual in the bigger picture”.
“However, as the dosage is higher than normal we would support washing after exposure.”
Council geothermal inspector Peter Brownbridge on Thursday told Rotorua Lakes councillors in an operations and monitoring committee meeting that the incident was “a man-made event”.
He said the immediate area was not known for hot ground, fumaroles or springs, and said one of his first actions on Wednesday was cranking three nearby geothermal wells, looking for an effect.
“We have pinpointed one well in particular which we think may have a broken casing at depth.”
He said one of the reasons the team looked hard at the wells was that the water was 98C at the surface and kicking up the clays that came from “great depth”, which indicated it was “more than just the naturally fed fumarole”.
He said rods ran down the suspect well and completed a deep quench, which involved injecting large volumes of cold water down it to cool the geothermal activity.
This proved the bore was responsible for the fumarole.
Councillor Tania Tapsell was concerned the area was not known for fumaroles or producing much heat, and asked if his could signal potential geothermal activity in areas that were thought to not be active.
Brownbridge was “not concerned” about that because this was a “man-made”, not natural feature.