Attachment 5 - Geotechnical Report · MCU18/0015

J000635-002-R-Rev1                                                                                  November 2018


0.55. An upper bound value may be adopted if supervision and certification of pile construction is carried out
by a geotechnical engineer.
Specialist piling contractors should be consulted with respect to selection of suitable pile types, detailed
design of piles, and pile testing. Detailed design of pile foundations should include geotechnical modelling
using, for example, Plaxis software.

6.4    Drainage & Erosion Control
Site drainage should be designed to readily remove surface water and to prevent ponding of water.
Stormwater should be piped to an engineer-designed dissipation system in the creek. Concentrated surface
water flows (e.g. roof runoff) should be avoided.
Vegetation disturbance should be minimised, and unprotected ground surfaces protected from erosion by
matting and/or revegetation. Vegetation along the creek banks must be maintained, and revegetation
undertaken in sparsely vegetated parts.
Creek bank stabilisation should be considered as part of the civil design (e.g. gabion baskets, drainage, use
of matting or ‘Geo-cell’ products).

7.0     SLOPE STABILITY ASSESSMENT & RECOMMENDATIONS
The Noosa Council (NC) Landslide and Flooding Overlay mapping indicates that parts of the site are in a
landslide hazard area. Image 2 presents an extract of the NC Landslide and Flooding Overlay Map for the
site.




                                                       Location of subject site




Image 2: Extract from NC Landslide and Flooding Overlay Map.

Based on the investigation results and previous stability modelling (03632248-001), the natural slopes are
considered to be close to equilibrium (i.e. factor of safety just above 1) for translational failures through the
surficial loose sands. The existing vegetation is contributing to natural stability of the slope through surface
protection and the stabilising effect of root systems.
The overall approach to managing slope stability for the proposed development should be to have a ‘non-
worsening’ impact on slope stability. The recommendations regarding footings, earthworks and drainage
provided in this report are made accordingly.
In addition, it is important that vegetation disturbance outside the building/pavement footprints is kept to a
minimum, and that suitable erosion protection is provided where vegetation is not present (e.g. matting
and/or revegetation). Temporary or permanent soil surface stabilisation in the form of cellular confinement
systems (e.g. ‘geo-cells’ or ‘geoweb’) could be undertaken in conjunction with revegetation.




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