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''This is not a design-by-committee or about beating up the council,'' meeting chairman Cr Andrew Noone said.
''Council is committed to finding a long-term solution but, ultimately, we are going to be relying on the best technical advice.''
City operations manager Tony Avery said it was still not clear what the best solution was.
''We don't actually know what needs to be done. We need to understand why it has failed, the dynamics of the beach and what to do to ensure it stays there for another 50, 60 or 100 years.''
Opus International Consultants, working with the Danish Hydraulic Institute, had been selected from 11 applicants to resolve the problem.
''We have quite a complex engineering problem in front of us,'' Opus senior project manager Steve Rollason said.
''The beach changes all the time.''
Council network maintenance engineer Peter Standring said remedial work had, so far, cost ratepayers $500,000.
''There's a lot to consider and there's too much at risk to do nothing. But, we have to balance that with the safety of the beach, its amenity value and its value to surfers. It has to tick all the boxes.''
However, many at the 200-strong forum expressed frustration at the remedial response to date.
St Clair resident James Dignan said the council had been ''treating the symptom, rather than the problem itself''' and suggested an artificial reef was needed to reduce the effects of wave action.
Dunedin resident Dave Ross said he was ''angry at the ongoing financial cost to ratepayers''.
''What is the guarantee this won't happen again?'' he asked.
Surfers Tony Ryder and Peter Haslemore said the sand erosion had led to the quality of the surf deteriorating in recent years.
''The wave levels haven't changed. The problem is the sand level is so low that the waves are hitting the sea wall for longer,'' Mr Haslemore said.
Graeme Newton, a St Clair Surf Lifesaving Club member for 47 years, said the damage was also endangering lives, as it prevented the club from launching a rescue on the beach.
''If we have a call-out, we can't respond. By the time we get there, someone will drown. It's as simple as that.''
Cr Noone said it was hoped a solution could be found before the surf club season opened at the end of October.
The council has set until the middle of next month for public submissions, with an Opus report due by mid-October.