Landslide Damage: Where It Happens and How to Fix It

Has your property experienced a landslide? Not sure where to start with stabilising the slope or remediating the damage? Here’s a practical guide on the process and the engineering options available.

Where Landslides Commonly Occur

• Landslides often occur where slopes are weakened by:

• Steep terrain – natural hillsides or cut slopes created during earthworks.

• Soil saturation – soils can lose strength if they become waterlogged after heavy or prolonged rainfall, particularly in clay or silt soils.

• Erosion – coastal cliffs, riverbanks, or areas where water undercuts a slope over time.

• Earthquakes – shaking can trigger slips in unstable or fractured ground.

• Human activity – vegetation clearance, uncontrolled stormwater, or poorly engineered excavations.

  
  

Understanding the trigger is the first step to ensuring the remediation addresses the cause, not just the symptoms.

Step 1: Geotechnical Assessment

The process usually starts with a geotechnical assessment, which includes:

• A site visit to observe visible slope damage.

• A ground investigation (such as boreholes or test pits) to confirm subsurface conditions.

• Laboratory testing where required to assess soil or rock strength.

The resulting geotechnical report will outline:

• The soil and rock layers present.

• The current and potential stability of the slope.

• Key considerations for selecting a remediation option.

Step 2: Selecting a Remediation Strategy

Your engineer will recommend solutions tailored to your site. Often, this involves collaboration between geotechnical engineers, structural engineers, and contractors. The goal is to balance safety, effectiveness, and cost.

Common Slope Stabilisation Options

• Retaining walls

  Widely used to hold soil in place and stabilise land. Variations include timber pole walls, crib walls, gabion baskets, and masonry or concrete block walls.

• Palisade walls

  In-ground retaining systems that anchor unstable material into deeper, stronger soils. These are typically invisible at the surface.

  
  

• Soil nails or rock bolts

  Steel rods drilled into the slope to tie loose material back into stable ground. Often paired with erosion control matting to allow vegetation regrowth.

• Sprayed concrete (shotcrete)

  A protective concrete layer applied directly to the slope. Effective for rockfall or shallow slips but less suited for large-scale landslides or sensitive environments.

Note: these are standard solutions, other specialised methods may be more appropriate depending on site conditions.

Step 3: Design, Consent, and Construction

Once a solution is selected:

• Detailed design is prepared with calculations, drawings, and specifications.

• Council consultation confirms whether resource or building consents are required. Supporting documents such as the geotechnical report are typically submitted.

• Construction is carried out by contractors, with engineers monitoring progress to ensure design compliance.

• Final certification is often required by council to sign off completed works.

  
  

Ready to Remediate?

Every site is different. A well-planned, engineered solution not only protects your property but also preserves its value.

Need help with your landslide? Talk to our team, we’ll provide you with a cost-effective and practical remediation strategy that gets your land stable again.