Rocks to replace mattress for coastal protectionA one-in-seven year storm event has led to a decision to change the way the Council land between Holmes Wharf and the Oamaru Creek is protected. Council had recently let a contract to protect the harbour land with sand mattresses. After a trial period to determine the best methods to install the sand mattresses, contractor Paul Smith Earthmoving was making good progress. Recently large waves from a storm out at sea struck the coastline and completely eroded the beach of sand and gravel meaning that there is now not enough left to shape the beach and install the mattress to the correct slope. Mayor Gary Kircher said, “With a combination of king tides and waves hitting the beach from an unusual angle, much of the stone, gravel and sand have been ripped from the beach, making it now unsuitable for the mattress to continue to be placed properly”. Assets Group Manager Neil Jorgensen said, “After advice from Council’s coastal engineer for the project, Gary Teear, we have made the decision to revert to using rocks to protect the reserve land and penguin colony in this area.” It was unfortunate that the sand mattress, which did its job during the storm, could no longer be used for the rest of the project. “We would like to thank Paul Smith Earthmoving for working through the change in conditions with us and helping to make the transition from mattress to rock seamless”. This has meant some increase in costs, with the large waves requiring $60k of emergency rock work, outside of the contract and the change to rock increasing the contract value from $520k to $590k. Both Council and Paul Smith Earthmoving staff have worked hard to keep the cost of the new work as low as possible. Mayor Gary said, “Unfortunately nature has now seen fit to remove so much material and substantially change the shape of the beach that we now have to go back to the rock protection. It will cost more money, but that work is underway. When completed, the coastline from Cape Wanbrow through to the end of the Kiwirail rock protection will be armoured against the sea’s waves and tides. It will require ongoing maintenance of course, but it will slow the advances that have eaten away so much of our land.” The sand mattress that has already been installed will remain in place for now and expect that it is likely to be re-covered by natural movement with beach material over the next few months.