Slope Stability Report 26-5-2019 OPW19-0193

TRUBUILT
SLOPE RISK ASSESSMENT REPORT



4.          RECOMMENDATIONS FOR DEVELOPMENT OF SITE

4.1         Site Preparation

The following recommendations are made for preparing the site for construction:

      •    Topsoil should be stripped from all areas where foundations and slabs will be constructed;
      •    Grass, shrubs and small trees should be cleared from the site, including large clumps of roots;
      •    Trees should be cleared with stumps and large roots grubbed from the site; holes created by grubbing
           should be filled with Select Fill in accordance with Section 4.3;
      •    Sections of the site where foundations and slabs on grade are to be constructed should be proof
           rolled to identify low strength materials;
      •    Where low strength materials are identified, they should be excavated and replaced with Select Fill in
           accordance with Section 4.3.

Stripped topsoil may be used to rehabilitate fill batter slopes.

Where large trees, clumps of trees, old buildings, swimming pools, ponds, effluent disposal systems or other
significant moisture source is being changed prior to construction, then the site may be subject to abnormal
moisture conditions. Abnormal moisture conditions could be detrimental to the slope stability of the site.

Further guidance on site preparation can be found in Australian Geoguide LR5 Water and Drainage and LR8
Hillside Construction.


4.2         Foundation Design and Construction

Based on the results of the site investigation and risk assessment it is recommended that the foundations
should comprise punch pad pole foundations or strip foundations using the foundation design parameters
given in Table 3.

Table 3 - Foundation design parameters
                               Founding Layer        Allowable
          Foundation Type                                                         Comments
                                   Name               Capacity
                                                                       Base of foundation to be not less
             Pole base         Weathered rock         175kPa
                                                                      than 1 diameter into intact LS rock
                                                                      Foundation to be proof compacted
                                                                     and any wet, soft or heaving ground
          Strip foundations    Weathered rock         100kPa
                                                                         excavated and replaced with
                                                                             compacted Select Fill

When designing foundations care should be taken to ensure that future temporary or permanent excavations
do not damage the foundations. Guidance for design of foundations under these conditions can be found in




LEONTAKIANAKOS-R-001                                 Page 12                                          26 May 2019