geotech

                              PROPOSED UNIT DEVELOPMENT
                              9 BOTTLEBRUSH AVENUE, NOOSA HEADS

1.0      INTRODUCTION
This report details the results of a geotechnical investigation undertaken for the proposed residential unit
development at 9 Bottlebrush Avenue, Noosa Heads. The investigation was performed by Tectonic for
Novato Group Pty Ltd ATF Bottlebrush Unit Trust, generally in accordance with Proposal P21109-Rev0,
dated 26 February 2021.

The investigation comprised drilling of boreholes at three locations across accessible areas of the
development footprint. This report summarises the results of the investigation and provides geotechnical
recommendations regarding earthworks and footings, together with temporary and permanent basement
retention. In summary, subject to the implementation of the recommendations made herein, it is assessed
that there would be a Low Risk of slope instability affecting the proposed development in accordance with
the Australian Geomechanics Society “Guidelines for Landslide Risk Management”, dated March 2007 (AGS
2007).

2.0      PROPOSED DEVELOPMENT
Preliminary architectural drawings were supplied to us (Ref. Zest Building Design, Project No. 21007,
Sheet Nos. A.001 to A.404 [not inclusive], Issue A, dated 7 July 2021). These plans indicate that the
development will comprise a three-storey building, over a single level basement carpark. Construction will
include a combination of masonry and lightweight materials (e.g. weatherboard cladding to walls etc.),
‘trimdeck’ roofing and suspended concrete floors.
No earthworks details were provided at the time of reporting; however, provided plans indicate that
excavations for the basement would likely be in the order of about 4 m deep in the rear with the cut
daylighting at the front. Localised filling less than 1 m high anticipated. Excavations will extend close to the
site boundaries and therefore, some form of temporary retention will be required. Isolated deeper
excavations may be required for the lift overrun pit and other elements.
Text Figure 1 below presents a layout plan and cross-sectional view of the proposed development.




Text Figure 1: Layout plan (LHS) and cross-sectional view (RHS) of proposed development, courtesy of Zest



3.0      METHOD OF INVESTIGATION
As part of our assessment, a desk-top study was carried out comprising a review of published geological
maps, slope stability studies as well as Noosa Shire Council (NSC) planning overlays and site information.

An experienced geotechnical engineer from Tectonic undertook a site walk-over on 5 May 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.

This was incorporated with a subsurface investigation comprising the drilling of three boreholes (designated
BH1 to BH3) in accessible areas across the site. Borehole BH1 was drilled to the front of the site using
Tectonics’ 4WD mounted solid flight auger rig to 7 m below ground level (BGL). Due to access restrictions
boreholes BH2 and BH3 were drilled to the rear and along the southern boundary, respectively, to 3 m BGL
using hand augering techniques.



13 July 2021
Report No. 21169-001-Rev0                                 1