Slope Stability Report 26-5-2019 OPW19-0193

TRUBUILT
SLOPE RISK ASSESSMENT REPORT



AS2870 – 2011 Sections 6.2 and 6.3. Design for effect of trees in close proximity to foundations should
following the requirements of AS2870 – 2011 Appendix H.

The base of all foundations should be cleared of all loose or remoulded soil. It is recommended that all
shallow footing excavations be proof compacted using a 300mm vibrating plate compactor to ensure sufficient
density and reduce the effect of construction settlement. Foundation excavations should be protected from
the infiltration of water that may result in the swelling or softening of soil and weathered rock. Foundations
should be inspected by a registered geotechnical engineer prior to the placement of concrete to ensure that
they meet the requirements of this report and the foundation design.

Further guidance for construction on landslide prone sites is contained in Australian Geoguide LR8 Hillside
Construction.


4.3        Earthworks Recommendations

Where fill materials are required to change site levels or fill holes formed during site preparation, then Select
Fill should be used, which meets the following requirements:

      •   Well graded granular material, may be site sourced, imported or recycled;
      •   Less than 15% finer than 75µm, fines should be low to non-plastic;
      •   Less than 10% greater than 20mm, no material larger than 75mm;
      •   Free from contamination such as salt, hydrocarbons, chemicals, timber, palm fronds, cement fibre
          sheeting and pipes, collapsing soils, sensitive soils, untreated acid sulphate soils, soils that contain
          materials that are water soluble, asbestos or domestic, industrial, mine and/or building waste;
      •   Generally less than 5% inert waste, including plastic, bricks, concrete, small metal fragments or road
          building products (exceptions may apply to recycled materials);
      •   Less than 5% finely divided organic matter and no clumps of organic matter. Finely divided organic
          matter includes treated acid sulphate soils, small leaves, mulch, dispersed dried grass and roots to
          5mm;
      •   Generally, avoid rock that crushes or degrades during handling and compaction, or forms fragments
          that are elongated or platy, ie shale, siltstone, claystone, mudstone, some phyllites, slates and schists.

It is noted that site won fill will comprise phyllite. When phyllite is used as fill the rock particles tend to form
platy particles that are difficult to compact properly, and the rock material will tend to break down on
handling. It is imperative that this material be properly compacted to ensure that the fill platforms are fit for
purpose.

Fill material should be placed in a controlled manner to meet the requirements of AS3798 – 2007. All fill
materials should be placed in loose layers not exceeding 200mm thick, moistened and compacted using a
vibrating plate or roller to 95% SMDD. Smaller or light compaction equipment may require thinner layers to
ensure compaction through the full depth of the layer. Compaction using site machinery, flooding or static
rollers generally does not meet these requirements. Other fill materials may be used, but could have an
adverse effect on the site classification or slope performance.


LEONTAKIANAKOS-R-001                                  Page 13                                              26 May 2019