Waitaki District Council staff have advised councillors set to consider the erosion-prone road’s future next week that even closing the northern section of Beach Rd will cost the community at least $4.6 million.
They also note any decision should be considered in the light of engineers having recommended the southern section of the road should also be closed.
Staff recommend the council choose to close the northern section now and instruct staff to pursue low-cost options to keep walking and cycling access for as long as erosion allows — the option favoured by the most submitters in a public consultation last year.
The northern section of Beach Rd from Old Bones Lodge to the corner just before the North Otago Golf Club has been closed since last November after historic waste dumping sites, which were starting to be exposed by the erosion, were found to be much bigger than expected.
Holes left from digging up the stretch to extract 69,000 tonnes of old refuse have left the road unusable.
A report from council staff to the Waitaki District Council’s final meeting of the triennium next Tuesday considers options for the future.
Four options for keeping the road open are outlined, ranging in cost from $6.3m to $10m over a 40-year period — the life of a road.
The cheapest is to realign the road around the excavations, at $6.3m, but that would only keep it open for another five to 10 years.
Reopening it between Old Bones Lodge and Awamoa Rd only would cost $7.9m, while reopening the whole section permanently using the existing pavement and road surface and protecting it from erosion would cost $9.3m.
Reopening the road but with maintenance costs set at 75% of the $9.3m option, meaning the road surface would be in poor condition in 40 years’ time, when it would need to be closed anyway because of continued erosion, was the most expensive option, at $10m.
The two options for closing the section of road were removing it all now for $4.6m or closing it to vehicles and using it as a walkway and cycleway for the next 40 years, removing the road progressively as erosion occurred at a cost of $4.9m.
In both closure options Thousand Acre and Stonewall Rds would be widened now and water and wastewater mains would be fully realigned by 2065.
The council report also presented sobering reading about the south end of the road, between Thousand Acre Rd and Kakanui, which it said was also highly vulnerable to coastal erosion and likely to have to be closed in the short to medium term without expensive comprehensive rock protection.
A report from engineering firm Beca estimated the upfront cost of protecting that section of road was more than $17m and recommended that a managed retreat approach would be the most appropriate strategy to pursue, staff said.
"Any decision to reopen Beach Rd North should not be made without full consideration of the long-term status of Beach Rd South."
The public were consulted on the options for the northern section last year and the largest number of submissions (38%) was in favour of the managed retreat option of closing the road and using it as a walkway/cycleway as long as possible.
That was roughly twice the number that favoured reopening the road for its views and convenience.
Councillors will also have an additional option — to defer the decision to the incoming council.
