Geotechnical Investigation

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




AGS suggest that regulators generally accept risk levels of “low” or lower as a level of acceptable risk.
AGS prepared a semi-quantitative assessment tool for determining the level of risk for a site. The tool separates the
potential hazards for a site, from a stability context, and rates them with a level of risk frequency. The multiplication
of these individual risk frequency summates as the risk frequency rating which is then measured against the levels
of risk nominated by AGS.
The results of this analysis are shown in Table 1.
TABLE 1: AGS ASSESSMENT

                Hazard                         Likelihood               Consequence                      Risk Level
             Global Failure                      Possible                    Minor                         Moderate
         Creep in Shallow Soils                   Likely                  Insignificant                       Low
  Rotational or translational slide down         Possible                    Minor                         Moderate
                 the slope


Based on the results of the AGS assessment, the perceived risk based on the conditions encountered and information
available at the time of the assessment is “Moderate” for the current proposed construction. Where proposed
structures are set back a minimum of 1m from the edge of the slope batter the risk rating may be reduced to “Low”.

7         HILLSIDE CONSTRUCTION
The following works should be implemented in addition to other items highlighted within this document. These points
are considered to be typical good hillside construction practice as explained in attached documentation:
 All footings should be found in natural materials and should extend to a depth which will not adversely effect the
  existing battered slope.
 Fill should be limited to no more than 1 m and should be step keyed into the existing slope. The fill should be
  formed at no steeper than 3H:1V, unless retained by an engineered retention system. All fill should be placed in
  accordance with AS3798.
 Where slopes are not supported by an engineer designed support system, natural slopes within or near movement
  sensitive areas should be no steeper than 2.5H:1V.
 All stormwater and surface water is to be discharged by an approved stormwater drainage system. The use of
  subsurface drainage systems are not suitable unless greater than 50 m downslope from the envelope at this site.
 Ongoing maintenance of effluent wastewater areas are also considered mandatory. The location of the application
  area should be located below the proposed building.
 Plumbing and services must also not be allowed to leak and regular maintenance and inspections should be
  undertaken.
 Erosion protection of cut and fill batters will be required. Batters should incorporate crest and toe drainage.
  Batters should be vegetated appropriately to minimise erosion.
 Overland flow paths will need to be carefully directed to approved outlets to minimise erosion.

8         GEOTECHNICAL RECOMMENDATIONS
The following sections details specific geotechnical constraints or recommendations in addition to general hillside
construction notes.




Sunshine Coast | Brisbane | Gold Coast