14169-001-Rev0 17 Webb Rd -Revised Draft · 132002.220527.1

                             17 WEBB ROAD, SUNSHINE BEACH
                             PROPOSED RESIDENCE

Our observations of surface features relevant to the slope stability assessment are summarised as follows:

       Structures on the immediately surrounding properties are in good condition and show no signs of
        instability (i.e. no significant cracks in rigid structures, with walls and posts in vertical alignment).
       The site is located close to a beach foredune, which has a steep slope about 20 m to 30 m from the
        existing structures. No signs of recent instability were observed in the foredune, with the dune face
        relatively well vegetated and having a relatively linear and planar slope.
       No indications of global slope instability were observed on the site; i.e. no landslide scarps, tension
        cracks, distressed structures or groundwater seepage was evident.

5.0      SUBSURFACE INVESTIGATION FINDINGS
5.1      Regional Geology
The 1:100,000 scale Gympie Special Geological Map (Sheet 9444 and Part 9544) indicates that the site is
underlain by a Pleistocene age quartz sand dune, with a younger Holocene age dune forming a lower berm
closer to, and parallel with, the beach.

5.2      Subsurface Conditions
The subsurface conditions encountered in boreholes BH1 and BH3 were relatively consistent and
comprised:

       Silty sand fill of loose to medium density to between 0.15 m and 0.4 m BGL; then
                                          T
        Natural sand / silty sand grading from medium dense to dense or very dense with depth.

Pieces of indurated sand (Ref. Text Figure 8) were encountered from 2.8 m and 2.5 m BGL in boreholes
                                        AF
BH1 and BH3, respectively, with these boreholes terminating at 3.1 m and 3.2 m BGL.

Borehole BH2 encountered loose grading to dense sand and gravel fill, with hand auger refusal at 0.9 m
BGL. These fill materials may represent a stormwater or effluent soakage pit / trench.

DCP1 put down on the level grassed area to the east of the house indicates a similar density profile as
                               R

encountered in boreholes BH1 and BH3, with very dense materials inferred from about 2.5 m BGL.

Groundwater seepage was not encountered in the boreholes during the investigation. It should be noted that
groundwater seepage may develop following periods of heavy or prolonged rainfall.
                       D


For detailed descriptions of the soil units encountered in the boreholes, refer to the boreholes and DCP
reports, together with explanatory notes, attached in Appendix A.




Text Figure 8: Pieces of indurated sand recovered from borehole BH3



26 February 2015
Report No. 14169-001-Rev0                               6