Appendix D - Geotechnical Report

5.1.5             Proposed Lot 5
Proposed Lot 5 is dominated by a well defined, elongated spur, which extends from the south-eastern
corner, through the centre of the site; dipping ultimately in to the north-eastern corner of the block. A
broadly defined drainage feature was present to the north-western corner, which contained a dam, which
was holding water at the time of our assessment.
A shallow relief drainage line head was located in the south-western corner of the lot, but with
moderately inclined flanks (~10°), and the invert reaching about 15°. The drainage line was dry at the
time of our assessment, and would offer an opportunity for some upslope protection and diversion of
drainage for the proposed building area.
The proposed building location was positioned on top of a rounded spur crest, which was sloping at 8°
to 10° just off Black Mountain Range Road, then reducing to gently sloping ground of no more than 5°.
The crest at the building area was at least 20 m wide. Further to the north, the dip of the spur crest
reduced to 3° to 4°. The spur would be slightly divergent naturally, helping to spread surface water flows
down and away from the site. While the crest was gently sloping, and therefore may locally have poor
drainage characteristics (e.g. allowing ponding) the scale of the landform allows ample space for the
creation of effective diversion drainage.
Text Figure 10 below illustrates the key site features and building location on proposed Lot 5




     Text Figure 10: Site layout (courtesy MWA) and looking north along spur within proposed buiding
                                                area (RHS)


5.2               Geology
Published geology mapping1 (Ref. Text Figure 11 overleaf) indicates that the site is underlain by the
middle Triassic age Kin Kin Beds (green shading, denoted “Rk”). The Kin Kin Beds are a low grade
meta-sedimentary unit containing phyllites, and “strongly cleaved and commonly kinked mudstone with
thin siltstone laminae; [and] minor volcaniclastic sandstone.”
An inferred high angle thrust fault (black dashed line in Text Figure 11) is indicated in the mapping,
trending approximately north-west to south-east through the centre of the site.

1
    State of Queensland, Dept. of Natural Resources, Mines and Energy, Gympie Surface Geology, 1:100,000 scale, Sheet 9445, 2018


Geotechnical Investigation
10 June 2026 | 26073-001-Rev0                                                                                                      10