It has been suggested that a trial could take five years to allow time to evaluate whether a restored structure is effective at retaining sand on Dunedin’s beach.
The groyne can be pulled out at the end of the consent period if the trial is not successful or, if there are signs of success, a longer term can be requested.
Dunedin City Council is due to make a decision next week on whether or not to seek permission to restore a groyne.
An attempt by the municipality to determine that permission was not necessary, and that permission should be obtained via a cheaper and less cumbersome procedure, failed in February.
The move was made despite legal advice from Anderson Lloyd that success via this route was unlikely.
Dunedin Mayor Jules Radich, a supporter of cribbing, said last month the maneuver was worth a try, “to see if you can do it the easy way first.”
Beaten back on this bid by the Otago Regional Council, the City Council must now decide whether to pursue a resource permit.
Anderson Lloyd advised last November that expert evidence was normally required to support an application for resource and evidence consent for an evaluated groyne.
If support could not be obtained, an evaluation would need to be made on the likelihood of success and whether the application should proceed, the law firm said.
“It could prove simpler for a coastal expert to support a groyne as a trial to monitor its performance, rather than predicting its success over a longer period of time.
“If this is the case, a process may be more realistic to agree to.”
The consent process, from the date of submission of the application to a decision, can take up to six months.
City council staff estimated that the cost of permitting and construction could be about $500,000, or fall in the range of $345,000 to $720,000.
This consists of making an environmental impact assessment and technical assessments to support resource consent ($100,000 to $150,000), legal fees ($50,000 to $200,000), consent processing costs ($15,000 to $50,000), and building from a single row of piles stacked together ($180,000 to $320,000).
In addition, up to $50,000 can be spent annually on maintenance and between $25,000 and $60,000 on monitoring.
It was expected that $140,000 could be saved in construction costs (was $320,000) if pinus radiata wooden posts were used instead of Australian hardwood posts.
Anderson Lloyd said the council could choose to ask permission for a longer term, up to a maximum of 35 years, or a short term, “say five years”.
It was likely that an application for resource consent would require expert advice on coastal processes and engineering, landscape and visual effects, marine ecology and planning.
It was “reasonably likely” that the application would have to be notified publicly, “because the environment is a public space, the proposal may affect the public and there is a high level of public interest”.
In a summary of a February pre-application meeting, the Otago Regional Council said limited notice or public notice of the application was a possibility.
The regional council also reiterated that groyne repair cannot be considered a permissible activity under coastal rules.
Legal advice to the Wynn Williams Regional Council last month was that the rules did not allow “reconstruction or replacement of those parts of a groyne structure which have been absent for many years.”
Anderson Lloyd had already made an argument in November that a restored groyne could be considered a like-for-like replacement with a slim chance of success.
“This is because we expect [the regional council] would take a conservative approach and be less likely to accept a new groyne as a permissible replacement or reconstruction, as the original structure has been largely absent for some time.
Groynes have been a feature of St Clair Beach since the early 1900s, but they have often fallen into disrepair.
Mr. Radich has consistently argued that they were effective when new or repaired, citing photographic evidence and engineering reports.
In their report to elected members ahead of next week’s meeting, city council staff highlighted two options: seeking permission for a trial crib and the status quo.
Among the benefits cited for a trial was that it would provide a tangible example of the council’s effort to respond to erosion, allow sand to accumulate at the groyne site, and be easily removed if necessary .
The lack of a budget for a crib trial was a disadvantage.
The status quo was described as continuing technical investigation of a groyne or groynes and other coastal management options in the coastal plan from St. Clair to St. Kilda.
This could “provide an opportunity for continued public engagement to discuss the technical assessments for the various coastal management options,” council officials said.
However, the time frame required for various engineering assessments requires “continuation of temporary measures to control coastal erosion”.