Thousands spent on remedial work
The popular coastal walkway at Second Beach, St Clair, has reopened to the public after a three-month project to repair slumping of the track.
Cracks first appeared along a 35m section of the track in August, and a geotechnical engineer was engaged to monitor the cracking and slumping identified by Dunedin City Council staff, Parks and Recreation acting group manager Jendi Paterson said.
It was found the slumping was due to rainwater softening the soil and wave action undermining the hillside, she said.
Track access was restricted in November, as the slumping had continued to accelerate in the wet weather, narrowing the track and exposing walkers to an unsafe drop.
Council parks operations manager Hamish Black said the whole coastline was under “constant erosion”, which had been exacerbated at the Second Beach track by the infiltration of rain water.
“Because we have had such a wet spring and summer, that continual seepage of ground water from the hillside has contributed to the ongoing slumping,” Mr Black said.
The DCC had contracted specialist drilling company Helidrill to sink 16 metal rods, each 4.25m in length, into the bedrock as an anchor for a retaining wall.
This was topped with a sturdy wooden fence to protect track users from the drop. Repairs to the track surface were also carried out.
Remedial work cost $17,000 and the geotechnical advice $10,000, bringing the project total to $27,000, Mr Black said. “The work we have done is quite extensive and, while it doesn’t fully negate ground movement in the future, it does strengthen the track in a narrow area,” he said. “We were mindful [in doing the work] that this is a track that is used by everyone and that it needs to be accessible in terms of its surfacing.”
Given the track’s close proximity to St Clair esplanade and its popularity, the work had been completed as quickly as possible, he said. “It has been good to get the track reopened.”
Monitoring of the track would continue informally, especially after any significant rain events.
Council parks staff and contractors would maintain a visual monitoring, and Mr Black was sure track users would also relay any concerns. “We know this is an area that is constantly under attack by erosion, so it is a matter of identifying problem areas and watching the ground,” he said.