This page contains updates on coastal projects that we are leading. These projects target addressing the more long-term coastal hazards we are facing.
St Clair Seawall Rock Revetment
St Clair Sewall residual life report in 2023 highlighted how the eastern side of the St Clair seawall was under at risk of undermining and needed to be addressed. This project included reshaping and replenishing the rock revetment of the seawall to prevent undermining and to add to the longevity of the seawall’s life.
Approximately 1100 tons of rocks were delivered by Fulton Hogan, ranging from approximately 0.8m to 1.5m diameter. These rocks were placed and interlocked at the base of the seawall.
Kettle Park Geobags
DCC has also led work on the emergency erosion protection of Kettle Park historic landfill, which includes installing of two layers of Mega Container Geobags, which are approximately 500m long.
The Moana Rua geobag (sand sausage) walls protect the historic landfill of Kettle Park from severe erosion caused by high swells and storms. They are a temporary measure and are expected to protect the historic landfill for at least five years.
Since landfill material was found extending into the beach’s dune system , the risk of it being exposed following winter storms had to be mitigated. The geobags will give us time to develop a long-term plan to prevent the escape of landfill material.
Further background:
The Kettle Park landfill operated from about 1900 to the 1960s, when it was capped and a sports field developed over the top. It re-emerged when a series of storms caused significant coastal erosion in 2007 and exposed the toe of the landfill, leading to tests which found traces of arsenic, asbestos and other industrial chemicals in nearby sand dunes. About 10m of dune has been eroded, exposing pieces of concrete, brick and other rubble placed there in 2007 to protect the landfill, although this material is not contaminated.
The storm activity in the past 10 to 15 years and the over-steepening of the dune gradually affected the stability of the dune system, presenting the risk of exposing the contaminated material.
The DCC has undertaken a three-stage investigation of the landfill, looking into its content and extent, the risk of contaminant discharge from dune erosion, and developing options to lower the risk of contaminant discharge.
Plan of Moana Rua Geobag project
