The Dunedin City Council agreed this week a remediation action plan needed to be prepared for Kettle Park.
This would include excavating some of the former landfill there to get ahead of the risk of it being exposed by coastal erosion and reshaping sand dunes.
The estimated cost is $35 million, not including contingency money.
Council transport group manager Jeanine Benson said the council needed to get cracking on forming the plan ahead of a pitch for government funding.
The council intends to cart landfill material to the new Smooth Hill landfill, due to open about 2030.
Councillors decided council staff should engage with the Ministry for the Environment about requirements for disposal of remediated waste.
This sprang out of concern about what the council might need to do to make contaminated material suitable for the new landfill, such as by diluting it.
Cr Jim O’Malley said this could make a significant difference to the project’s cost.
Dunedin Mayor Jules Radich asked staff whether building up sand on the beach nearby would be worthwhile, mitigating the erosion threat.
Groynes had worked well in the past at St Clair Beach, he said.
"Sand on the beach is the most effective protection from winter storms and incursion of the sea," Mr Radich said.
Staff said their focus was on preparing a plan that would align with government funding.
Groynes being part of a broader plan for the coastal area remained a possibility, they signalled.
Cr Brent Weatherall said he was comfortable with the remediation project’s timing aligning with the opening of the Smooth Hill landfill.
"In the interim, between now and 2031, I can see no reason why we cannot proceed with groyne trials, which will hopefully be pushed further by the incoming council."
Cr Andrew Whiley said he was frustrated consultants seemed to have missed key historical facts.
He particularly highlighted the impact a temporary Tahuna outfall pier had at St Kilda Beach in 2008.
The Otago Daily Times reported at the time a surf lifeguard commented the pier had functioned like a groyne, trapping sand and creating a "great right-hander [wave]".
Cr Lee Vandervis voted against the council’s resolutions, as he did not want to signal financial commitment "for something which may not need doing for years or decades".
