Report finds cost to move Franz Josef township close to $600m

Franz Josef Top 10 Holiday Park near the Franz Josef Glacier on the West Coast with village in foreground at bottom. Photo / File

It would cost nearly $600 million to relocate Franz Josef Glacier township - hemmed in by earthquake and flooding hazards - according to a report commissioned for the West Coast Regional Council.

Moving the town to a completely new site to the north, near Lake Mapourika, could cost between anywhere between $570m to more than $610m based on a current cost-benefit assessment in the report by consultants Tonkin and Taylor.

However, abandoning the current town site is the least preferred.

The report identifies three packages of options to deal with the imminent risk to the township, which sits atop the Alpine Fault and is constricted by the Waiho (Waiau) River to the south and west.

The regional council has been designated as the lead agency in collaboration with government agencies.

The report notes that the natural challenges facing Franz Josef leave it in an "unique position".

Its low rating base and population base of just 510 compared with its significant tourism role means high value is at stake. The town has a high "if not the highest" visitor-to-resident ratio in the country.

The three option packages are:

• To 'avoid' the most significant challenges by shifting entirely to Lake Mapourika to avoid the Waiho River flood zone and away from the Alpine Fault.
• To 'live with' by decreasing stopbank management and allowing the river to fan out naturally on the south bank.
•'Defend' by building up stopbanks and gravel extraction to enable the town to stay where it is.
• Each package has a different level of risk posed by significant natural challenges, namely the faultline and the unstable geology of the mountainous area.

A cost-benefit analysis designed to show the best value for money over a 50-year period indicated the latter two "perform the best".

High up-front costs to move entirely and the long-term nature of the benefits "expected to accrue" translated to a lower cost-benefit, according to the executive summary.

However, modelling for the options was only over a 50-year period, and therefore significantly underestimated the true costs of continually intervening to maintain Franz Josef at its current location.

Tonkin and Taylor said a multi criteria assessment framework used to filter the long list of options and the cost-benefit analysis were only part of the context that should help decision making.

"There are always choices about what the future of Franz Josef should look like. Decision-making also needs to consider risk appetite to certain natural hazards risks, the nature of natural hazard risk occurring in perpetuity, and future aspirations for the town."

It meant more detailed consideration and community engagement about "non-financial aspects" was needed.

The finalised report is being released to the Franz Josef community in the lead up to future consultation and is expected to be released publicly tomorrow.

- Greymouth Star