20013-001-Rev0 Flooded Gum Pl - geotech report

Mr Andrew Jensen                                                                                  20013-001-Rev0
                                                                                                  4 February 2020

Earthworks have recently been carried out to form a building pad in the south-eastern part of the site. The
building pad is approximately 25 m wide and 50 m long. We are advised that the future building works will
comprise construction of a retaining wall less than 1 m high to support the lower part of the cutting along the
southern side of the building pad. A conventional residence will be built, likely single or double storey with a
slab on the ground floor.

1.2       Method and Scope of Investigation
As part of our geotechnical assessment, a desk-top study was carried out comprising a review of published
geological maps and slope stability studies.

A walk-over survey was conducted by an experienced geotechnical engineer from Tectonic on 17 January
2020, to make an appraisal of the general condition of the site regarding topography, drainage, earthworks,
vegetation cover, geology, erosion, and slope stability. The results of the desk-top study and walkover
survey are included in Section 2 below.

1.3       Qualifications of Responsible Engineer
This report has been prepared by Mr. David Pollock, an RPEQ with more than 14 years’ experience in
geotechnical engineering, including numerous slope stability projects.

2.0        DESCRIPTION OF EXISTING CONDITIONS
2.1       Geology
The published geological map for the region 1 indicates that the underlying geology comprises the early to
middle Triassic age Kin Kin Beds (Ref. Text Figure 3), noted to comprise “arenite, argillite and phyllite.”




                                                                      Approximate Site Location




Text Figure 3: Extract from Gympie Special Geology Map

The cutting for the building pad exposed a shallow cover of about 1 m depth of residual soil comprising very
stiff, gravelly clay which graded to highly weathered phyllite of very low strength. The rock was noted have a
sub-vertical, well developed fabric (Ref. Text Figure 4).




1
    1:100,000 Gympie Special Geology Map, Sheet 9445, DME, 1999 (1:100, 000)




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