A wooden groyne is to be trialled at Buffalo Beach off the end of the already completed Stage Two rock seawall.

The structure is expected to promote enough sand build-up towards the north of Buffalo Beach to negate the construction of a further rock seawall, as well as allow for more dune planting.

The Thames-Coromandel District Council says a wooden groyne, similar to the one pictured, will be trialled at Buffalo Beach. Photo: Thinkstock

Engineering company Tonkin and Taylor Ltd has been commissioned to design and obtain resource consent for the trial groyne, which could allow it to stay in place for up to five years.

Acting Mercury Bay area manager Allan Tiplady says this timeframe is considered appropriate as it will allow the Thames-Coromandel District Council to sufficiently measure the groyne's benefits.

'A groyne of wooded piling and lagging will provide the desired flexibility and essentially allow a physical model to be developed at the site,” says Allan.

'Other types of groyne structures were looked at including rock and gabion bag, but the wood was decided on as the final option because it can extend in height compared to other structures.”

The groyne will also be designed to allow for pedestrian access, so people can still walk along the beach unimpeded.

A draft Assessment of Effects on the Environment recommends the groyne be made out of timber and extend 25m out from the end of Stage Two of the rock wall at the Buffalo Memorial.

It will involve driving piles into the foreshore when the area is not inundated by seawater, then a four metre wide trench will be excavated one metre below the foreshore level to create the necessary space and self-retaining slope to construct the timber lagging.

The lagging will then be fixed to one side of the piles and geotextile will be laid on the inner face of the lagging.

Allan adds that to remove the structure this process will be reversed and machinery will lift and remove the piles as the last step.

'If the trial's successful we could look at commissioning a design for a permanent structure, obtain the necessary coastal permits and install the structure.”

During this time a university of Waikato study on Mercury Bay/Whitianga Harbour delta hydrodynamic research will be completed and will help inform a decision in the long-term.

Stage Two construction of the Buffalo Beach rock seawall between the public toilets and the Buffalo Memorial site was completed earlier this year.

There is resource consent on hand for Stage Three of a rock seawall, which could extend the wall further if required.