The flooded Redclyffe substation, responsible for much of Napier and Hawke’s Bay’s power outage, had been identified as critically at risk in 2020 and planning for resilience work was slated to begin later this year - had funding been approved.
Although it is questionable whether any resilience work would have stood up to Cyclone Gabrielle, the fact the substation could have been strengthened against flooding makes a strong case for accelerating resilience work on at-risk infrastructure.
Redclyffe was initially constructed in 1927 and then upgraded in the 1970s. Transpower Chief Executive Alison Andrew told the Herald it was built to “high resilience standards at the time (1 in 100-year flood)”.
Clearly, that wasn’t enough - and Andrew noted that evolving understanding of resilience means that now substations are built to withstand a 1 in 450-year flood.
The problem for Transpower, which owns and operates New Zealand’s national grid infrastructure, is that there are many other substations just like Redclyffe that are vulnerable to failure in a flood.
Andrew said that in 2020, Transpower sought to understand the flood risks of its assets under various scenarios.
Twelve substations, including Redclyffe, were identified as “critical for improving resilience to a one-in-250-year flood”. More detailed study is scheduled for this year. Too late to keep the power on in Hawke’s Bay, but hopefully soon enough to improve resilience to future floods.
Transpower is keen to get budget to improve resilience and has put up a plan to invest $109m between 2025 and 2030 in resilience. This includes resilience from everything including flooding, which takes out substations and transmission lines that cross rivers, to solar storms - these are the enormous flares on the sun which are disruptive enough to knock out electrical equipment on earth.
That funding for this resilience comes from transmission charges that form a portion of people’s power bills. As a state monopoly, Transpower’s expenditure is regulated by the Commerce Commission which has to approve the balance between fair transmission prices and expenditure plans.
“Our base funding includes incremental improvements in resilience as part of ongoing maintenance. In addition to that we have taken action and proposed a resilience programme as part of our next regulatory funding period. We have requested approval to spend an extra $109 million on resilience work.
“As part of this plan, planning for any additional resilience measures for Redclyffe would have commenced later this year in anticipation of the funding being approved,” Andrew said.
Andrew cited the Wairau Rd substation built in 2013 as an example of something built to a modern standard.
It was built to withstand a 1 in 450-year event.
“During the Auckland floods in late January this substation had 1.5m of water through it but remained fully operational and power continued to flow to 500,000 people as a result,” Andrew said.
“All infrastructure providers strive to achieve the right balance of affordability, sustainability and reliability from their assets. It is not possible for any infrastructure company to build its network to the extent that outages never occur.
“However, Cyclone Gabrielle will prompt infrastructure providers, including Transpower, to reconsider our investment approach to resilience and whether it is sufficient for the future,” Andrew said.
As the crisis across the North Island drags on, questions are being asked about what gets rebuilt and how the rebuild takes into account the fact that devastating storms are likely to become more frequent.
Prime Minister Chris Hipkins said it was “almost certainly” time to rethink parts of the road network, he said.
“We have to get real about some of the roads and the fact we are going to have to move some of the roads to where they are more resilient,” he said.
It is difficult to get a picture of what is vulnerable and how much it would cost to replace - or how much it would cost to manage the retreat of vulnerable infrastructure.
A 2019 analysis of coastal flooding exposure - different to the inland flooding seen after the cyclone - reckoned that by 1m of sea level rise occurring by 2100 would make over 1,441km of roads, 101km of railways, 72km of electricity transmission lines, 141 electricity structures, 14 airports and over 4,000km of three-water pipelines exposed and in need of some form of strengthening, either in the form of protection or relocation.
A study by Local Government NZ estimated that half a metre of sea level rise would affect council infrastructure with a replacement value of $2.7b, increasing to $7.8b if sea levels rose 1.5m.