Slope Stability AG-220616-RPT-G-01_[Rev A]

                                                                                                        ABN 51 640 311 842
                                                                                                        arcosgroup.com.au
                                                                                       Sunshine Coast | Brisbane | Gold Coast




1         INTRODUCTION
Arcos Unit Group Pty Ltd (Arcos Group) was commissioned to undertake a geotechnical investigation for the project
at the location described on the title page of this report.
This report outlines the results of the investigation, laboratory testing, analysis, and interpretive reporting on the
following items:
 Review of the existing slope stability hazards, their attributed risks and impacts of the proposed development in
  alignment with the practices set out within the Australian Geomechanics Society guidelines; and,
 Provide recommendations from a geotechnical context that will avoid or reduce any potential instability.
This report must be kept in entirety. The use of this document is exclusively undertaken in accordance with our terms
and conditions.

2         REGIONAL GEOLOGY
The site is in an area underlain by Late Triassic to early Jurassic aged Myrtle Creek Sandstone, which typically
comprises “Quartzose sandstone, orthoquartzite, sublabile to labile sandstone, siltstone, shale.”.

3         EXISTING STABILITY RISK
Local authorities prepare mapping tools to aid in assessing potential slope stability requirements. The mapping tools
are a “high level” approach where the site specific investigations are specific to a particular site/allotment. It is
important to note that where a site specific investigation and slope stability assessment are undertaken, they take
precedence.
Reference to the available overlays for the area show the site has been initially mapped as “Moderate” in terms of
landslide hazard.

4         GEOTECHNICAL INVESTIGATION
A geotechnical investigation was undertaken by Ground Drill Pty Ltd for the purposes of a site classification and
effluent report. The findings from their investigation are detailed in their report, a copy of which is attached; however
in summary, the conditions encountered consisted of gravelly silty sand overlying sandy clay, underlain by rock from
approximately 0.9 m below the existing ground surface. No groundwater was noted in their investigation. The
information from this previous investigation has been used as part of the analysis undertaken by Arcos. If any
discrepancies between the conditions reported by Ground Drill and the actual site conditions exist, reassessment of
the slope stability may be required.

5         ASSESSMENT
Geotechnical comments are based on the factual findings of the investigation, best practice, local experience,
published correlations; however, are fundamentally founded in opinion and this should be considered.
An assessment was undertaken by a Geotechnical Engineer. The proposed dwelling location is situated towards the
north-western corner of the block. The site slopes down from the north-western corner towards the south-eastern
side of the block. The slope angles are fairly uniformed at approximately 20°. No obvious signs of disturbed ground,
tension cracks or hummocks were noted in the vicinity of the proposed residence. The mature trees on site were all
observed to be typically vertical with no misshapen or curved trunks. Misshapen or curved trunks are usually good
indicators for previous slope instability.




Sunshine Coast | Brisbane | Gold Coast