Appendix B - Geotechnical Assessment · OPW23/0179

 Project No. PG-10375                                                                               Page | 5
 June 2023
 Ref: PG-10375, 2023-06-09, LTR VER 1
 Michael Cullen – Geotechnical Investigation - Proposed Residence, 128 Gympie Terrace, Noosaville




5.0 GROUNDWATER

Groundwater was noted in the boreholes at depths of 1.2m and 1.3m at the time of
drilling. Water levels can be expected to vary with seasonal and climatic conditions.

Typically, the groundwater levels in the area are encountered at levels of
approximately RL 0.5m to RL 1.0m. Fluctuations of +/- 0.5m are typically noted in the
area.

Increases in the groundwater levels often occur following significant rainfall events
(floods) with the groundwater levels to as much as RL 1.5m to RL 2.0m being noted in
the area.

6.0 SITE CLASSIFICATION

The investigation and laboratory test results indicate that from a reactivity perspective,
the development site could be considered equivalent to Class ‘M’, in 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) could be difficult
           to manage and consideration could be given to the disposal of this material.