Landslide Hazard Report_compressed

Specialists in transport geotechnics

        Residential Developments” and certified by a geotechnical inspection and testing
        authority.
    •   Where fill is placed over side slopes, the subgrade slopes should be cut to form a series
        of horizontal terraces to ensure that the fill is bonded to the subgrade.
    •   Cut and fill batters must not exceed a slope of 2H:1V.
    •   All cut and fill earthworks of greater than 1.0 m height or depth must be designed by a
        professional engineer and checked for stability.
    •   All retaining structures greater than 1.0 m high must be designed by a professional
        engineer in accordance with AS4678-2002 “Earth Retaining Structures”. The design
        should be adequately designed for earth pressures, surcharges and elevated ground
        water conditions and fully account for sloped backfill and retained ground. The adopted
        design should also include conservatively sized drainage and regularly scheduled
        maintenance measures. Retaining walls should be founded into hard residual soils or
        weathered rock. The actual required depth of founding will need to be designed to
        provide an adequate factor of safety against global instability for the height of retained
        material.
    •   Earthworks should only be undertaken during periods when ground conditions are
        relatively dry and there is no threat of prolonged rainfall. A risk assessment should be
        undertaken prior to undertaking any earthworks operations on the site.
6.5 Inspection, Monitoring and Maintenance
Inspection, monitoring and maintenance is a key activity required for maintaining expected short-
and long-term performance of any existing structure and proposed works element. Generic
mitigations are noted below.
The owner of the property should be responsible for:
   •    Maintaining adequate surface drainage path in and out of the property and piping the
        drainage outlet away from the immediate slope to avoid potential scouring on the slope
        surface.
   •    Fixing/repairing the leaking or broken underground drainage/sewer pipes as soon as the
        fault has been identified.
   •    Undertaking periodic visual inspection of the property and surrounds for any cracking,
        ground movement etc (say every 6 months too annually or after large storm periods).
   •    Where the risk levels are determined to be higher then an inspection by qualified and
        suitably experienced personnel is required.
   •    Maintaining vegetation cover or other means of surface protection (as applicable) inside
        the property boundary to minimise surface infiltration into underlying foundation materials.
   •    Where practical, encouraging/facilitating vegetation growth on the crest and slope below
        the house.
   •    Seeking appropriate geotechnical and design advice if any construction activities
        including renovation/addition or replacement are planned within the extent of the property.
   •    Following Council’s relevant regulatory requirements for new construction inside the
        property.




10 May 2022                       CGC-SR-2022-011-R01-Rev01                                Page 15