RESPONSE TO FURTHER ADVICE -Geotechnical Report · MCU25/0054

                                                                                                       PTG/02023 – 0001 – Rev1


5 FIELD INVESTIGATION
The fieldwork scope was intended to comprise four (4) boreholes drilled to between 3.0 m and 6.0 m depth using a
4WD utility mounted GT-10 drilling rig fitted with 100 mm diameter solid flight augers for the deeper borehole and a
67 mm diameter hand auger for the shallower boreholes. Before beginning the fieldwork, it was unknown that the front
lawn comprised of astroturf underlain by concrete. Assessment was undertaken at the time of works and the borehole
BH1 was abandoned due to inability to penetrate the underlying concrete. As a result, the fieldwork comprised three
(3) boreholes drilled to depths of 0.3 m to 3.0 m using a hand auger at the rear of the property. The drilling was
undertaken by an experienced driller and geotechnician who logged the bores and collected samples. Refusal of the
hand auger was encountered at borehole BH4 on localised tree root systems.

Disturbed samples of representative soil types were collected from the boreholes for soil description and classification
purposes and subsequent laboratory testing. The visual-tactile description and classification methods undertaken on
disturbed samples, and shown on the attached logs, are described in accordance with AS 1726:2017.

DCP testing was undertaken adjacent to the boreholes from the surface with the number of blows to achieve 100 mm
depth penetration recorded in accordance with AS 1289.6.3.2.

Soil consistency and relative density described on the borehole logs were inferred from the DCP results, tactile
assessment and published correlations.

The approximate borehole locations and numbers are shown on the Test Location Plan attached in Appendix 1. The
borehole log report sheets are attached in Appendix 2.

It is anticipated that further field investigation will be required in order to attain a satisfactory depth for further
commentary to be provided regarding the property.



6 GEOTECHNICAL MODEL
In summary, the soil profile encountered within the boreholes in the rear portion of the property generally comprised
a surficial 0.1 m thick layer of topsoil then silty sand to the termination depth. Table 1 summarises the soils
encountered within the boreholes.

Table 1: Summary of Materials Encountered in Boreholes
          Borehole No.                                   Topsoil (m)                      Silty Sand (m)
               BH2                                         0.0 – 0.1                         0.1 – 3.0TD
               BH3                                         0.0 – 0.1                         0.1 – 3.0TD
               BH4                                         0.0 – 0.1                         0.1 – 0.3R
Notes: NE = not encountered, R = refusal depth, TD = termination depth

Dynamic cone penetrometer (DCP) testing undertaken indicated topsoil and silty sand have a loose relative density
gradually increasing in density with depth.

Groundwater was not encountered during the drilling of the boreholes. It should be noted that groundwater levels can
be perched and fluctuate seasonally and during and after heavy rainfall events. Given this natural variability, the sandy
soils encountered, and the site’s relative proximity to a tidal river, it is prudent to assume that water levels can and
will fluctuate.



7 LABORATORY TESTING AND RESULTS
Soil samples collected from the completed boreholes were submitted for subsequent laboratory testing. Given the
inability to complete the investigation, limited sampling was undertaken at the time of fieldwork. A subsequent follow-
up investigation is to be undertaken when access is deemed appropriate. Below, testing has been undertaken to
provide commentary on the severity and presence of acid sulphate soils.




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