Geotechnical Investigation Report

4 FIELD INVESTIGATION

The fieldwork undertaken by Core Consultants included two (2) hand auger boreholes drilled to 4.0 m below existing
ground levels. Dynamic cone penetrometer (DCP) testing was undertaken adjacent to the boreholes.

Testing and subsurface logging of the boreholes was undertaken by a geotechnical engineer, in accordance with
AS1762-2017 - Geotechnical Site Investigations. The geotechnical investigation report is attached in Appendix 1.

5 GEOTECHNICAL MODEL

Table 1 summarises the soils encountered within the hand auger boreholes. In summary the soil profile encountered
within the boreholes generally comprised a surficial 0.1m to 0.18 m thick layer of topsoil, potentially underlain by
uncontrolled sand fill to depths up to 1.0 m, underlain again by natural dune sands to termination depths.

Table 1: Summary of Materials Encountered in Hand Auger Boreholes

ste Ra Topsoil\(m) Fill- SAND (m) Natural - SP SAND (m)
oe
1

0.0 - 0.18 0.18 - 1.0 1.0 - 4.07
2 0.0 - 0.1 N/E 0.1- 4.0"

Note: TD = termination depth, N/E = material not encountered in auger hole

Dynamic cone penetrometer (DCP) testing undertaken indicated:
Fill soils typically have a loose relative density;
Natural sand soils from depths of 0.1 m to 1.6 m typically have a loose relative density;
Natural sand soils from depths of 1.6 m typically have a medium dense relative density, grading to dense at depths
of approximately 3.5 m.

Groundwater was not encountered during the drilling of the hand auger boreholes. It should be noted that groundwater
levels can be perched and fluctuate seasonally and during and after heavy rainfall events. Given this natural variability,
it is prudent to assume that water levels can fluctuate.

6 GEOTECHNICAL COMMENTS

The geotechnical comments in this report are based on the factual information collected during the fieldwork
conducted by Core Consultants, best practice, local experience and published literature, however they are
fundamentally opinion.

In summary, the ground conditions that are likely to be encountered at the site can be characterised as comprising a
0.1 m - to 0.18 m surficial layer of topsoil, potentially underlain by loose uncontrolled sand fill to depths up to 1.0 m,
underlain again by loose natural dune sands to depths up to 1.6 m. Below 1.6 m natural sands are expected to be
medium dense, grading to dense with depth.

Based on the ground conditions and the provided development plans, it is likely that the most suitable foundation
system for the building would comprise high level pad and strip footings supported on natural medium dense sand.
Piled foundations are recommended for heavily loaded or movement intolerant structures.

6.1 EARTHWORKS ADVICE

6.1.1 SUBGRADE PREPARATION

To achieve a uniformly well compacted subgrade to support slabs and pavements, the subgrade should be uniformly
compacted to a minimum 100% standard compaction. To prepare the subgrade, the upper 0.3 m depth (particularly
in cut areas) may need to be scarified, moisture-conditioned and recompacted to a minimum 100% minimum dry
density ratio (DDR) with a moisture variation not exceeding +2% of the optimum moisture content (OMC) followed
by a test roll and sealing as soon as practical.