Discussions over restoring the beach have been held for about 10 years, involving Te Rauone Beach Coast Care Committee, Te Runanga o Otakou and Port Otago.
The beach had become badly eroded, causing the sand dunes to diminish.
The rock groynes would protect and hold sand from being washed away due to wind, natural tidal effects, boat wakes and dredging.
Each structure was planned to extend up to 90 metres from the shore into the harbour, requiring an estimated 15,000 tonnes of rock.
Weather permitting, SouthRoads — which was awarded the tender for the project, which was estimated to cost $3million — would have the structures built by December.
Port Otago chief executive Kevin Winders said it was a way for the port to give back to the community.
"With our dredging project, there has always been an inference that we have contributed to the erosion of the beach.
"Science sort of says that is a bit of us and a lot of nature so when we look at it, our contribution, it is about acknowledging that we had a part to play and ensuring that beach is preserved for the next generation," he said.
Port Otago would be responsible for the sand replenishment once the structures were built by depositing the sand it collected from its dredging programmes across the harbour. That process was expected to take a further three months.
"We have talked about it for so long and now we are down to spending some money and making it happen so it is pretty exciting," he said.
Te Rauone Beach Coast Care Committee member Des Smith said the community had waited a long time for the project to start.
"We are all over the moon, after years it is finally happening and to see it come together is great.
Mr Smith described the project as a "long haul".
"Our small committee has worked really hard over the years to bring it to fruition and it has been very challenging at times.
"We came across obstacles and we had to overcome them. It would have been very easy at times to give it away but we hung in there," he said.
