Attachment 2 - Geotechnical Stability Assessment

Project No. PG-2096                                                                                          Page | 5
May 2022
Ref: PG-2096, 2019-02-21, GR VER 4
Clare Design – Geotechnical Stability Assessment - Proposed Residence, 22 Arakoon Crescent, Sunshine Beach




It is recommended that the following site preparation and earthworks procedures be
carried out as part of the earthworks procedures during development.

          All earthworks operations should be carried out in general accordance with
           AS 3798-2007 "Guidelines on Earthworks for Commercial and Residential
           Developments".
          Trafficability across the site at the time of the investigation was assessed to be
           poor due to the steepness of the site.
          All topsoil (i.e. soil containing organic matter) and soils containing deleterious
           matter should be stripped from the construction area at the commencement
           of the earthworks operation.
          The majority of the soils on site will be suitable for re-use as structural fill,
           provided material is free of organic matter and deleterious material. It is likely
           that the soils require conditioning to bring the soils to optimum If the soils were
           overly moist, difficulty in achieving compaction of the materials will be
           encountered and moisture conditioning will be required.
          Imported fill should be of fair to good quality with a minimum Soaked CBR
           value of 10%, a maximum Iss=1.0% and a maximum particle size of 75mm or a
           ‘clean’ sand.
          All filling should be undertaken in layer thicknesses of approximately 250mm
           (or as appropriate for the compaction equipment being used). Fill should be
           compacted to a minimum dry density ratio of 95% Standard in accordance
           with AS1289 5.1.1 or a minimum density index of 65% in accordance with
           AS1289 5.6.1.
          Density testing should be carried out to check the standard of compaction
           achieved and the placement moisture content. The frequency and extent of
           testing should be as per guidelines in AS.3798-2007.
          All earthworks operations should be performed under Pacific Geotech’s
           supervision, in general accordance with the requirements of AS3798.

6.0 POTENTIAL GROUND SURFACE MOVEMENTS

It is recommended that the readers satisfy themselves that the use of AS 2870-2011 is
applicable for the proposed design and the above site classification re-confirmed
following the completion of the bulk earthworks operation.

Site investigation and laboratory test results indicate the development site would be
classified Class S in accordance with AS 2870-2011 'Residential Slabs and Footings',
from a reactivity perspective.