Attachment F - Geotechnical Report

                               PROPOSED COMMERCIAL & RESIDENTIAL DEVELOPMENT
                               30-32 DOONELLA ST, TEWANTIN

5.0       INVESTIGATION FINDINGS
5.1        Geology
The 1:100,000 scale Gympie Special Geological Map (Sheet 9445 and Part 9545, DME 1999) indicates that
the site is underlain by the late Triassic to Jurassic age Myrtle Creek Sandstone (denoted as “RJdm”)
comprising “quartzose sandstone, orthoquartzite”. Mapping also indicates that this geological unit in the
Tewantin area exhibits a deep weathering profile of leached, kaolinised and mottled rocks. An extract from
the geological map is shown in Text Figure 5 below.




                                                                      Site position




                                                                  Weathering
                                                                  pattern




Text Figure 5: Extract from Gympie Special Geology Map

5.2       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.

Boreholes generally encountered consistent subsurface profiles which can be summarised as follows:
         Loose to medium dense silty/clayey sands and gravels together with firm to stiff sandy/silty clays
          (fill and natural materials) to depths of between 0.75 m and 1.5 m BGL; overlying
         Mostly very stiff, medium to high plasticity natural silty clays (inferred residual soils derived from
          weathering of the Myrtle Creek Sandstone) to borehole termination at depths of 3 m to 6 m BGL.
Fill materials were encountered to 0.75 m depth in all boreholes, except borehole BH4 where inferred
natural soils were intersected directly under the silty sand topsoil (which typically extended up to 250 mm
deep).

Groundwater seepage was not encountered in any of the boreholes at the time of investigation, with soils
being moist. However, it should be noted that groundwater seepage may develop at shallow depths within
permeable horizons, particularly following periods of heavy or prolonged rainfall.




22 June 2018
Report No. 18151-001-Rev0                                5