Attachment 5 - Geotechnical Assessment · MCU18/0015

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4.0 METHOD OF INVESTIGATION
41 Fieldwork

Initially, eight boreholes (designated BH1 to BH8) were drilled by hand augering, with
dynamic cone penetrometer (DCP) tests conducted from the ground surface adjacent to each
borehole. However, due to the loose and dry nature of the near surface sands, it was only
possible to extend the boreholes to depths of up to 0.9 m, below which the boreholes were
found to collapse.

In order to prevent collapse of the open boreholes, a second round of hand augering was
conducted with casing installed to depths of up to about 1.5 m. Additional hand augered
boreholes were drilled at three locations (BH2A, BH4A and BH7A). DCP tests were
conducted from the surface and within the boreholes at 1.5 m intervals in ordetto reduce the
effect of friction build up on the DCP rods and, thus, on the test results.

Test pits were dug using a 1.5 tonne excavator with 350 mnitoothed bucketto depths of up to
2.3 m. Test Pits TP5 and TP 6 were dug adjacent to,two of the previously drilled boreholes
(BH5 and BH6), which encountered shallow refusal toYDCP testing, Test Pit TP8 was dug in
sand adjacent to the creek. Test pits TP9 and. TP10 were dug on ‘lie clay slopes on the eastern
side of the creek. The size of excavator used.on’the site and.the number of test pits dug on the
eastern side of the creek was restricted by severe access limitations imposed by existing
structures and the density of vegetation cover as shown on Photograph 3.

Disturbed and undisturbed\(U50) tube samples obtained from the boreholes and test pits were
returned to Golder Associates’ Maroochydore laboratory prior to dispatch for geotechnical
testing (ref. Section’4.2),

The fieldwork was undertaken"by experienced geotechnical personnel on 9 October (initial
boreholes) and 16 October (second round boreholes and test pits), 2003. The borehole and
test pit locations are shown in Figure 1. Results of the fieldwork are presented in the Reports
of Boreholes, Test Pits DCP Tests in Appendix A, along with explanatory notes. Surface
levels shown on the borehole and test pit reports have been interpolated from survey
information supplied by the client.

Golder Associates