Erosion at Ocean Beach

'Ocean Beach' is the name given to the beach that stretches for nearly four kilometres, from the point at St Clair, where the Hot Salt Water pool is located, to Lawyers Head.

We are working with various groups to ensure we come up with the best management plan for erosion in this area.

Background to Ocean Beach erosion

Erosion on this stretch of beach known as Ocean Beach is not new. In the 19^th century its dunes were breached on various occasions. In 1884, a sea wall at St Clair was undermined, and two years later it was completely destroyed. It was replaced by a rubble wall nearly 200m long in 1888, but in November 1889, most of that wall was broken down by wave action and much of the Esplanade washed away. There was further inundation in 1891 and 1898, with water flooding many houses and flowing along drainage ditches to reach as far as Hillside Road. A sea wall made of concrete panels was built in 1912, and this remained unchanged for more than 90 years.

Dune breaches and sand loss were reduced in the 20^th century, although they certainly continued. The photo below shows significant loss of sand at St Clair in 1976.

Recent Erosion

Another wall was built on the seaward side of the wall in 2003/04. A number of geotextile tubes (known as "sand sausages") were filled with sand and installed in the dunes to the east of the sea wall. The completion of this work late in 2004 was followed by a number of storm events that damaged the access ramp and stairs. These were repaired, but there have been on going issues with subsequent storm damage that are still to be repaired.

In 2007, storms exposed the sand sausages. These were slashed by vandals, immediately before a further series of storm events. The storms caused significant damage to the dune system and sand levels on the beach were lowered significantly. An Emergency Response Team (ERT) was appointed to manage the situation and identify the best way forward. Emergency repairs were undertaken in July and August 2007. These included construction of Reno blankets (a metal framework holding rocks to reduce sand erosion), and replacing sand on the beach to offset the sand lost during the storms. This work has been approved by the Council as a holding pattern, and continues today.

Over the 2007/08 summer, the beach profile rose and no further serious erosion of the dune face occurred. The only on-beach work required over the summer has been the removal of some of the clay capping on the dune tops either side of Moana Rua Road to lessen the risk of further erosion of the dunes, and further placement of sand over the sand sausages to prevent them from being exposed.