A report into the collapse of a electricity transmission tower in Northland in June this year has confirmed the removal of nuts from the tower's baseplates was to blame, and highlighted some oversights by the organisation responsible for the national grid, Transpower.
It also revealed the economic impact of the tower collapse on June 20 as between $37.5m and $80m, and that without distributed electricity generation it would have been more. It left about 88,000 people without power.
Energy Minister Simeon Brown said the cause being the removal of the tower's nuts was as expected, but "underlying factors" that contributed to the tower's collapse were "entirely avoidable".
Maintenance work was being carried out on a tower at Glorit by a crew from Omexom. An earlier report found too many nuts at the bottom of three legs of the power pylon were removed.
"The report found an overreliance by Transpower on service providers to ensure that critical assets are maintained. It also found that identifiable risks were missed, including concerns that were raised internally.
“The report shows that concerns were raised by a senior engineer within Transpower in 2021 regarding a gap in the knowledge of maintenance crews undertaking foundation work, but that the recommendations for improvement by Transpower were not acted on."
Those knowledge gaps included baseplate refurbishment work.
He said that failure to act led to "terrible consequences" for the people of Northland, but there was "also evidence that the removal of all nuts from more than one tower leg was not a one-off event".
At a press conference, Brown and independent chair Sarah Sinclair couldn't say how many times it had happened.
“These are incredibly concerning findings, and the report identifies a number of recommendations that I expect Transpower will fully accept and act with urgency to address,” Brown said.
The report recommended that Transpower review its policies on the escalation of service provider noncompliance events. It also calls for greater reporting on service providers.
The report was satisfied with the restoration of power after the tower collapsed, concluding it was carried out quickly, safely and efficiently, and highlighted the importance of distributed generation.
Energy Minister Simeon Brown. (Source: 1News)
Brown said distributed generation was able to meet 45% of the peak demand, which meant many customers could get "up and running" shortly after the collapse.
"Without distributed electricity generation, the economic cost to Northland would have been far greater. The Electricity Authority estimates that having access to that distributed electricity generation saved Northland consumers at least $26 million.
“The report recommends a review of the rules which limit the amount of power that can be generated by electricity distributors. The Government has already announced that we will be easing the restrictions that currently exist on EDBs so they can increase electricity generation and bolster regional resilience. Details will be confirmed by Cabinet later this year."
Brown said transmission towers were critical infrastructure and should be treated as such by all parties managing and maintaining them.
"I will be writing to the Electricity Authority to express my expectation that the recommendations are implemented. The Electricity Authority will also be monitoring implementation of the recommendations."
Pylon collapse: Inexperienced workers were not supervised properly
The incident cut power to Northland and parts of Auckland after all the nuts on three legs of the pylon were removed.
New Zealand
Thu, Aug 1
3:13
Crew removed too many nuts from bottom of pylon before collapse
Too many nuts were removed from the legs connected to the base plates, something that was "unprecedented and inconceivable", Transpower said.
New Zealand
Mon, Jun 24
Recommendations include:
- Transpower improving processes for maintenance work for baseplate refurbishment, and ensuring its contractors are more appropriately trained, monitored and compliant.
- Transpower should require its service providers to review and revise their work procedures for baseplate refurbishment to ensure they align with Transpower’s technical specifications.
- Transpower ensuring regular reporting and escalation of non-compliance by service providers to the Transpower’s Board so that the Board and senior management can exercise effective governance and oversight.
- The Electricity Authority developing options to amend the Electricity Code to allow for more regional resilience through distributors able to generate more on their own networks.
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