Geotech Report · OPW26/0094

Project No. PG-10899                                                                                                           Page | 5
November 2023
Ref: PG-10899, 2023-10-16, GR VER 1
DD Sunnyside CD Sunnyside Pty Ltd – Geotechnical Investigation - Proposed Residence, 30 Mossman Court, Noosa Heads




accordance with AS 2870-2011 'Residential Slabs and                                                            Footings',   following
appropriate ground improvement works under the footings.

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.

7.0 EARTHWORKS AND SITE PREPARATION CONSIDERATIONS

Earthworks are expected to comprise cuts of up to 3m for the proposed basement
excavation.    Some over-excavation may be required to allow for ground
improvement works.

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
           fair to good with no difficulties encountered at the time of the investigation.
           Following stripping and excavation for the basement, the exposed sands will
           be difficult to traffic for conventional vehicles. Consideration could be given
           to adopting a 150mm layer of pavement gravel as a working platform across
           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. Dirty sands (i.e. >5% fine content), particularly
           the upper level sands (existing fill), could be difficult to manage and
           consideration could be given to the disposal of this material.
     •     The stripped surface should be proof rolled using a vibrating roller or a large
           vibrating plate compactor (say 300kg), to identify areas of weak surficial soils
           and to compact the upper level material.
     •     The “clean” sands on site will be suitable for re-use as structural fill, provided
           material is free of organic matter and deleterious material. The silty sand may
           prove difficult to re-use and consideration should be given to preferential
           disposal of this material.
     •     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 98% Standard in accordance
           with AS1289 5.1.1 for cohesive fill and 75% Density Index for non-cohesive fill
           (i.e. sand).