International experts are being called in to help plan for rising groundwater in South Dunedin.
Global environmental specialists Golder Associates and Netherlands-based not-for-profit Deltares have been contracted to study steps being taken to tackle rising groundwater internationally.
The lessons will then be applied to South Dunedin, where the Dunedin City Council and Otago Regional Council are preparing a work programme — subject to community consultation — to manage rising groundwater.
The two councils will share the $36,000 cost of contracting the international organisations for the project, which is expected to take about 10 weeks.
ORC engineering, hazards and science director Dr Gavin Palmer said many cities around the world were facing the issue of rising groundwater, "so much can be learned from experience elsewhere".
"This review will incorporate what protection options have been used elsewhere, what has worked and lessons learnt," he said.
"This information, along with our own science and monitoring, will help us and the community to identify viable options for South Dunedin."
DCC water and waste group manager Laura McElhone said the councils needed a better understanding of how communities elsewhere in the world managed the challenge of rising groundwater, "particularly in areas that have similar social, economic and environmental settings to South Dunedin".
"We are at the beginning of a long-term project to plan for climate change. Once we have a lot of this technical information together, we will be able to discuss next steps with the community."
The initiative comes three years after the DCC commissioned a report by Beca, which in 2014 recommended a $75million network of pumps and wells, to draw groundwater away from South Dunedin over the coming decades.
Pumps would be needed first, perhaps by 2040, and could cost $10million to install, while wells needed by 2090 could cost $65million, initial estimates suggested.
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None of the flooding that occurred in Dunedin in 2015, 2016, 2017, 1929 etc was caused by high groundwater levels. High groundwater was always the result, but the cause has always been the DCC: either because there was no stormwater system, in earlier years, or because the stormwater system did not meet modern-day standards. Even with the new pump screen, the system is seriously deficient in South Dunedin, Mosgiel and other parts of the city.
The DCC water manager tells us that the South Dunedin system was installed to a low performance standard (by today's measures) and the DCC consultants tell us that in some places the performance is now even worse than when it was installed. The DCC should replace the old pipes instead of trying to promote their Climate Change paranoia. The ORC data shows that no rising groundwater has been detected in South Dunedin. There is no groundwater problem. The big problem is the DCC underfunding the city's essential infrastructure.
In Invercargill, the city council still isn't even designing to the 2010 New Zealand standard, a point I raised in my submission to the council last year... http://bit.ly/1NO4HsH TA's need to raise their game, at least DCC appears to be taking a strategic look at this.
It's important that the terms of reference for the consulting work include the worsening predictions for sea level rise based on recent observations. For example, NOAA (http://bit.ly/2lSWone) recently updated their estimates from 1 to around 2.5m rise, and I expect others to follow as the projections catch up with recent science (http://bit.ly/1YQbq6g, http://bit.ly/1YQbQJW, http://bit.ly/2lSNdmH). The PCE's report and other sources relied on by local government are outdated, and very conservative...