Keeping the water flowing: Wellington’s above-ground emergency water network
Being a Wellingtonian means being prepared. Tsunami, landslides, and the very real risk of the ‘big one’ are facts of life for New Zealand’s capital. Getting prepared to respond is one challenge for Wellington’s growing population of 412,000 residents. But, what about the resilience to get back to normal? And how is that possible when it may take up to 100 days for water supply to be restored to many homes?
Wellington Water Limited is the council-owned water company that serves residents living in the region’s four cities – Upper Hutt, Hutt City, Porirua and Wellington.
Cardno has been working with Wellington Water on resilience planning since 2015. Through this work, we have helped identify the vulnerabilities of the water supply network that could lead to many suburbs being without water for 100 days or more, and led development of Wellington Water’s Towards 80-30-80 strategy. The long-term goal of this strategy is to have 80 per cent of customers, receiving 80 per cent of their water supply needs within 30 days after a major seismic event.
Decisions on how to apply 80-30-80 coincided with a magnitude 7.8 earthquake striking Kaikōura in November 2016. Centred only a few hundred kilometres from Wellington City, this shake-up was close enough to trigger a call for accelerated investment in water resilience for the region.
Antony Cameron is Cardno NZ’s Technical Director of Infrastructure Strategy. He says the key to unlocking investment in resilience is making resilience simple and communicating clearly. “You have to place yourself in somebody else’s shoes. To me, resilience is about asking what would my friends or family consider reasonable in the circumstances. Once you’re in that frame of mind, you can start to see resilience through a number of interesting lenses. Many of these lenses contributed to the development of Wellington Water’s innovative 80-30-80 strategy.”
We can’t and won’t be there
“The typical approach to water supply resilience in many cities is one of ‘we must be there in the event of a disaster.’ We decided to approach things differently – and based the model on communicating pragmatically. It’s about delivering water supply on the basis that we can’t, and won’t be there in the event of a disaster,” says Antony.
Having worked across many engineering sectors, Antony has witnessed first-hand the time, effort and cost required to reinstate major infrastructure. Recovery is even more challenging when transport, electricity, communications, and water services all need to be restored simultaneously. “We knew we would have a big problem on our hands, but we needed some real data to really get a good understanding of the scale of this problem,” he says.
To assist in the development of the 80-30-80 strategy, Cardno turned to the use of leading cellular analytics, to understand how people moved in and around the region based on real data. This proved invaluable to our resilience team in establishing that more than 100,000 people may attempt to walk out of Wellington City’s CBD after the earthquake. It also helped confirm that the lack of transport connections across the region would effectively create 17 miniature ‘islands’ until transport routes were restored. This modelling also revealed that people may be walking home for up to four days, and how this would affect the need for water supplies across these islands.
This information was a key foundation informing the community-centric approach of the Community Infrastructure Resilience Programme.
“The data told us we can’t be there from day one. And even if we could be, the response may be patchy. This was a key foundation in our community-centric approach,” says Antony. “We recognised we needed to empower communities with resilient water services within each island, while also planning for a utility-led response.”
Resilience starts at home
The first stage in delivering to this strategy was stronger promotion to Wellington households to store emergency water at home. Across NZ the survival minimum is recommended to be three litres a day, for three days. In Wellington, this simply isn’t enough. The message needed to shift to a level of at least 20 litres for every person, every day – for at least seven days.
Strategy into action
New Zealand Country Manager Rod James says the 7.8 earthquake in November 2016 led to a sharper focus on the region’s vulnerable infrastructure.
“It was only days after the Kaikōura quake that we were driving the 80-30-80 strategy into action. We focused on providing the community with low-cost network alternatives, and quick-win solutions to make sure residents would be able to access local sources of water.”
Rod says the first step in accelerating investment was helping to share the recommendations of the 80-30-80 strategy with central government. Cardno’s advice and summarised investment strategy ticked the right boxes for central and local government, ultimately securing $6 million of central government funding which was matched 50/50 by Wellington’s four city councils.
“The $12 million Community Infrastructure Resilience programme was established in June 2017. The core objective is ensuring the availability of 20 litres of emergency water for every person, every day from day eight after a major event. And providing the water within 1,000 metres of every home across the four city council areas.
“I am extremely proud of the way that our teams have converted this strategy into action. It has been intense – completing the region’s most comprehensive hydrogeological study and water source investigation, the design and delivery of 22 low-cost modular water treatment stations, a comprehensive water distribution network, and an integrated emergency plan.
“Our hydrogeology experts, project managers, engineers, water processing engineers, community engagement specialists, analysts and advisors – everyone in the Cardno Wellington office has played a part.”
No matter the size of the earthquake, and no matter the location, each community within 17 ‘islands’ can access tools and maintain emergency water supplies until network services are restored to homes.
The programme is scheduled to deliver the full 20 litre target by 1 July 2018, and will be fully completed in August/September 2018.