Compiled Reference Documents - OPW25/0053 (As Published)

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Report on Geotechnical Investigation
Proposed Retaining Wall
10 Surfside Court, Sunshine Beach


1. Introduction

This report presents the results of a geotechnical investigation undertaken by Douglas Partners
Pty Ltd (Douglas) for a proposed retaining wall at 10 Surfside Court, Sunshine Beach.

The investigation was undertaken at the request of the Mort Family Trust in general accordance
with Douglas’ proposal 222438.01.P.001.Rev0 dated 19 May 2024.

It is understood that a retaining wall up to 2.0 m height is proposed to be built along the northern
lot boundary.
The aim of the investigation was to assess the following:
•    subsurface conditions including groundwater;
•    earthworks and site preparation, including suitability of site soils for reuse and compaction
     standards;
•    suitable foundation types and allowable bearing pressures;
•    lateral earth pressure and geotechnical parameters for retaining walls;
•    stability assessment of retaining wall using Slope/W.

The investigation comprised the drilling of four bores, followed by laboratory testing of selected
samples. Details of the field work and laboratory testing are presented in this report, together
with comments on the items listed above.

This report must be read in conjunction with the attached notes entitled “About This Report”
along with any other attached explanatory notes and should be kept in its entirety without
separation of individual page or sections.


2. Previous Investigation

Douglas previously carried out a geotechnical investigation on this site. As part of the previous
investigation, one bore (designated as Bore 1) was drilled to 6.0 m depth and two additional
dynamic cone penetrometer tests (designated as DCPs 2 and 3) were also carried out.

In summary, the subsurface conditions previously encountered comprised clayey sand and sandy
clay fill to between 1.5 m depth overlying loose to medium dense sand to 3.8 m depth. Underlying
the sand, stiff to very stiff residual sandy clay/clayey sand was encountered to 6.0 m.

Groundwater seepage was previously observed at 2.1 m depth in Bore 1.

Where appropriate, the results from the previous investigations has been used to supplement
the results of this investigation and have been included in this report for completeness.




Proposed Retaining Wall                                                            222438.01.R.001.Rev0
10 Surfside Court, Sunshine Beach                                                         August 2024