Geotechnical Report (1) · MCU21/0212

                             PROPOSED RESIDENCE
                             66 SEAVIEW TERRACE, SUNSHINE BEACH

3.0      METHOD OF INVESTIGATION

3.1      Fieldwork
An experienced engineering geologist from Tectonic undertook a site walk-over on 15 September 2021 to
visually assess any indicators of past slope instability. The walk-over included assessment of soil
exposures, surface drainage conditions, topography, evidence of erosion or past instability, and vegetation
coverage/condition.

At the time of the walkover two boreholes (designated BH1 and BH2) were undertaken at the main break in
slope from the site to the dune face (approximate to the eastern site boundary), and towards the toe of the
dune, respectively. In situ testing utilising the DCP method was completed from surface adjacent to each
borehole, and at selected depths downhole. In addition, standalone DCP testing was also conducted through
inferred fill embankment materials off Seaview Terrace to the western boundary of the site, and at an
intermediate point, around half-way down the dune face. Hand augers were taken to depths of between 3 m
and 6 m BGL.
A separate phase of investigation was completed on 8 October 2021. A small excavator owned and
operated by Bebrok was utilised to temporarily remove and replace boulders to the site frontage, and
undertake minor vegetation clearing and earthworks to create a relatively level drilling platform within the
proposed building envelope. One borehole (designated BH3) was drilled to 31.45 m BGL. This borehole
was drilled using a tracked vehicle mounted Hydrapower Scout rotary drill rig, owned and operated by
Drillsure Geotechnical Pty Ltd. This drill rig was equipped with solid flight augering and rotary wash boring
capabilities, allowing deep penetration through the sand dune profile.
In situ testing in borehole BH3 comprised standard penetration tests (SPT) generally at 1.5 m intervals.
Boreholes BH1 and BH2 were backfilled with drilling spoil and left slightly mounded at the ground surface. A
standpipe was installed in borehole BH3, to a depth of 6 m BGL for groundwater monitoring. Disturbed soil
samples were recovered from SPT spoon, and auger cuttings at shallower depth.
The engineering geologist was responsible for logging soil profiles and maintaining investigation practices in
accordance with AS1726 Geotechnical site investigations, supervising in situ testing, and recovering
samples.
Borehole and DCP reports are attached in Appendix A, together with explanatory notes. Borehole locations
are shown in Figure 1.

3.2      Geotechnical Laboratory Testing
Select disturbed soil samples were dispatched to the NATA accredited laboratory of QC Testing, located in
Yandina, for geotechnical testing and comprised two particle size distribution (PSD) tests for soil
classification purposes. Geotechnical laboratory testing was undertaken in accordance with Australian
Standard AS1289 Method for Testing Soils for Engineering Purposes. Laboratory test results are
summarised in Section 4.6, and test certificates are attached in Appendix B.




23 November 2021
Report No. 21370-001-Rev0                              2