Engineer says let erosion take South Dunedin

Allowing coastal erosion to reclaim Kettle Park should be the start of a wider retreat from South Dunedin, a Dunedin City Council hearings committee has heard.

The call came from Sustainable Dunedin City co-chairman Phillip Cole - a former civil engineer of 31 years' experience - as the committee considered a second day of submissions on its draft management plan for Ocean Beach.

However, the idea was swiftly dismissed by the hearings committee, with one member, Cr Paul Hudson, calling it "not acceptable".

The draft plan, by consultant Tonkin and Taylor, suggested ways of tackling erosion between St Clair and St Kilda beaches, with Middle Beach the worst-affected area.

It recommended the continuation of a holding pattern for 10 years, followed by either managed retreat from the area or construction over 10 to 50 years of a buried backstop wall.

Some submitters - including the Dunedin Rugby Football Club - have already objected to a managed retreat that would mean the loss of sports grounds at nearby Kettle Park.

Speaking yesterday, Mr Cole argued a managed retreat could be the start of a wider withdrawal from South Dunedin, at least as far inland as Hillside Rd, over the longer term.

That would "let the sea decide what South Dunedin is," he said.

"With managed retreat, it gives you impetus to start the relocation of South Dunedin," he said.

Such a relocation would be expensive, but so too would protecting the area, he argued.

The council already faced the prospect of spending millions of dollars upgrading ageing water infrastructure in South Dunedin.

Housing in the area was also ageing, with properties likely to be "beyond repair" in 20 or 30 years, and the area was under increasing risk of flooding, from sea-level rise and a rising water table, he warned.

Cr Hudson said he was concerned by the suggestion the sea be allowed to "take over South Dunedin", which was "not acceptable".

Committee chairman Cr Colin Weatherall agreed, saying - in deliberations yesterday afternoon - Mr Cole's suggestion was beyond the scope of the committee, which was tasked with considering submissions on Ocean Beach options.

However, the idea was not the only one to prompt concern at yesterday's hearing, with Cr Hudson also worried by a submission from the Department of Conservation.

The Doc submission supported a managed retreat from Middle Beach - rather than construction of a buried backstop wall - in line with the New Zealand Coastal Policy Statement 2010, which sought to reduce the need for walls and other "engineering interventions".

Cr Hudson said that raised questions about whether the council - after five years' work - was "setting itself up to fail", if it agreed to an engineering solution that would be opposed by Doc when resource consents were sought from the Otago Regional Council (ORC).

Cr Hudson asked for more information from Tonkin and Taylor senior coastal engineer Richard Reinen-Hamill, who was present to answer questions from the committee.

Cr Hudson also asked whether the council should investigate a cost-sharing arrangement with the ORC to help pay for the work.

Tonkin and Taylor's estimates showed a managed retreat - including a clean-up of an old landfill under Kettle Park - could cost $11 million-$19 million, while a buried backstop wall could cost $8 million-$13 million.

The hearing was adjourned to allow Mr Reinen-Hamill to prepare a report.

Cr Weatherall said he hoped the hearing would resume next month, with a decision a week later. The hearings committee would then make recommendations to the council's community development committee, before final approval was sought at a full council meeting.


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