geotech

                               PROPOSED UNIT DEVELOPMENT
                               9 BOTTLEBRUSH AVENUE, NOOSA HEADS

4.4         Subsurface Conditions
Detailed descriptions of the subsurface conditions encountered in the boreholes are provided in the
borehole reports attached in Appendix A, along with definition sheets which describe terms and
abbreviations used on the reports. The subsurface conditions encountered in the boreholes are
summarised as follows:

          Asphalt – 15 mm thick (borehole BH1 only); then
          Fill – comprising loose sandy gravel and silty sand to 0.8 m BGL (borehole BH1 only); then or from
           the ground surface
          Natural Sands – comprising silty and poorly graded sands mostly being very loose/loose to depths
           of between 1.6 m and 2.2 m BGL; becoming medium dense (or denser) then increasing to dense
           below depths of about 4 m BGL.

Table 1 below, summarises the subsurface profile in each borehole.
Table 1: Summary of Subsurface Profiles
                                                                   Very
                                                                                Medium Dense        Dense (or
 Borehole No.            Asphalt                Fill           Loose/Loose
                                                                                   Sands          denser) Sands
                                                                  Sands

          BH1           0 – 0.015           0.015 – 0.8           0.8 – 2.2       2.2 – 4.0         4.0 – 7.0TD


          BH2               NE                  NE                 0 – 1.6       1.6 – 3.0TD       4.0* – 4.6DCP


          BH3               NE                  NE                 0 – 1.6       1.6 – 3.0TD       4.0* – 4.8DCP

Notes: 1.         Depths noted in m BGL at time of investigation (5 May 2021)
       2.         NE denotes not encountered
       3.         TD denotes borehole terminated at target depth

       4.         * inferred from DCP testing
       5.         DCP denotes DCP termination depth



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
occur at shallower depths, and at locations not previously observed, 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 relatively
large catchment; however, most runoff from upslope of the property is anticipated to be intercepted by the
existing stormwater infrastructure from the neighbouring structures and streets.

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.



13 July 2021
Report No. 21169-001-Rev0                                 5