Geotehnical Investigation Report · OPW22/0140

                              PROPOSED UNIT DEVELOPMENT
                              37 BOTTLEBRUSH AVENUE, NOOSA HEADS

Table 1 below summarises the subsurface profile in each borehole.
Table 1: Summary of Subsurface Profiles
                                                                  Very
                                                                                  Medium Dense
 Borehole No.          Pavement                 Fill           Loose/Loose                         Dense Sand
                                                                                      Sand
                                                                  Sand

      BH1               0 – 0.06            0.06 – 0.4               N/E            0.4 – 3.1       3.1 – 6.0TD

      BH2               0 – 0.02            0.02 – 0.8            0.8 – 1.1         1.1 – 3TD        4.1 – 4.5*

      BH3               0 – 0.02            0.02 – 1.2            1.2 – 2.5         2.5 – 3TD        3.8 – 5.2*
Notes: 1.        Depths noted in m BGL at time of investigation (21 April 2022)
       2.        NE denotes not encountered
       3.        TD denotes borehole terminated at target depth

       4.        * inferred from DCP testing

4.5         Groundwater
No signs of groundwater seepage (‘springs’) were observed during our walk-over. Groundwater was not
encountered in the boreholes at the time of investigation.

Groundwater conditions are expected to be reflective of prevailing weather conditions and seepage may
develop particularly following periods of prolonged or heavy rainfall.

4.6         Surface Drainage
Surface drainage would be expected to follow natural surface contours to the south-west towards
Bottlebrush Avenue, thus draining into the roadside drainage system. It is noted that the site has a
relatively large catchment; however, most runoff from upslope of the property is anticipated to be
intercepted by the existing stormwater infrastructure associated with the neighboring structures and
roadside drainage systems.

Given the sandy nature of the site, rainfall would normally be anticipated to infiltrate the ground surface.
However, as the proposed development will occupy a large part of the block, significant run-off from hard
surfaces will occur. Nevertheless, where directed into swales rather than pipes, such run-off would be
expected to infiltrate into the natural sands relatively rapidly.

No significant surface run-off features were noted during our assessment (e.g. deep rilling or scour/wash out
scars). This indicates that significant overland flow is generally absent during rainfall events.
Recommendations to improve surface drainage as part of the development works are provided in
Section 6.5.




13 May 2022
Report No. 22151-001-Rev0                                 6