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.
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.”
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.
Transpower accepts recommendations
More than 100,000 people in Northland had their power cut in the June incident. (Source: 1News)
In a statement, Transpower said it acknowledged and accepted the recommendations of the report, which “confirmed” their own independent report.
“The tower fell because the service provider (Omexom) crew performing routine baseplate maintenance work did not follow Omexom’s standard practice and removed all of the nuts from three of the tower’s four legs,” the company said.
Transpower executive general manager of grid delivery Mark Ryall said the company apologised again to all the consumers and businesses which were impacted by the power cut as a result of the tower fall.
“We accept the recommendations for Transpower in this report. They are generally in line with the recommendations already made in the report we commissioned, which was released last month. We are well underway with the actions in response to those recommendations and are updating our progress regularly on our website.”
“Our focus now is on the future. Our people are passionate about the work they do to ensure New Zealanders have a reliable electricity system. We are committed to doing whatever we can to ensure an event like this never happens again and to improving regional resilience.”
Omexom introduces changes to processes
Omexom New Zealand managing director Mornez Green reiterated his apology, and said the company undertook its own organisation-wide review which “introduced a range of changes to prevent recurrence of any similar event”.
“Since the event we have left no stone unturned on how we can ensure all our staff fully understand and adhere to procedures, and that our briefings, supervision and checking processes are the best in the industry.
“If this sounds like it is ‘back-to-basics’ then that is correct. We are absolutely committed to make all necessary changes. It is essential that this event, rare as it was, is never repeated.”
