Landslip Remediation & Retaining Wall in Auckland

When the Auckland Anniversary storm hit in 2023, it triggered slope failures across the region. On steep residential sites, that meant land loss close to homes, uncertainty for owners and difficult questions about safety, insurance and repair. At this property, a deep-seated slope failure developed beside the dwelling, threatening the stability of the land and raising serious concerns about the future use of the home.

Cook Costello was first engaged to assess the land damage and assist the owners through the insurance process. Our independent engineering assessment helped establish the likely cause and extent of the failure, supporting the owners’ claim for land damage cover. Following the successful claim, we continued our involvement through the full remediation phase.

Our Role Included: 

• Detailed geotechnical investigation to assess the landslide mechanism, subsurface conditions and ongoing stability risks 

• Development of a remedial stabilisation strategy suitable for a deep-seated slope failure 

• Integrated geotechnical and structural design of a retaining wall system to stabilise the slope adjacent to the dwelling 

• Preparation of consent documentation to support Auckland Council building consent 

• Construction monitoring and PS4 producer statements to confirm the works were completed in line with the design intent 

The solution combined robust geotechnical analysis with structural retaining wall design to provide a practical long-term stabilisation solution for the site. 

The slope has now been stabilised and the dwelling reoccupied. The site is better placed to withstand future heavy rainfall events than it was before the 2023 storm.

Importantly, the owners had one team from the first damage assessment through to final certification, providing continuity, clarity and support during a stressful and uncertain time.