RESPONSE TO FURTHER ADVICE -Geotechnical Report · MCU25/0054

                                                                                                                        PTG/02023 – 0001 – Rev1


                ENVIRONMENTAL – ACID SULPHATE SOILS
Soil samples were recovered every 0.25 m from the boreholes. Laboratory testing was undertaken in accordance with
the ‘National Acid Sulfate Soils Guidance: National acid sulfate soils sampling and identification methods manual’
(Department of Agriculture and Water Resources, 2018).

Laboratory testing included field pH (pHF) and field pH peroxide (pHFOX) tests in order to assess for the possible
presence of ASS. A summary of the results is presented below in Table 2. Laboratory reports of test results are
attached in Appendix 3.

Table 2: Summary of Acid Sulfate Soils Field pH Testing
  Borehole                                                            pHF                 pHFOX            Reactivity        pH Change
                         Depth (m)            Material
    No.                                                          (pH units)           (pH units)            Number           (pH units)
      BH2                  0.25                Sand                   6.9                  2.9                 3                4.0
                           0.50                Sand                   7.3                  3.2                 3                4.1
                           0.75                Sand                   6.8                  2.8                 3                4.0
                           1.00                Sand                   6.8                  3.0                 2                3.8
                           1.50                Sand                   6.9                  3.0                 2                3.9
                           2.50                Sand                   6.6                  3.1                 2                3.5
                           2.75                Sand                   6.8                  3.0                 2                3.8
                           3.00                Sand                   6.8                  2.2                 2                4.6
      BH3                  0.25                Sand                   6.0                  2.6                 2                3.3
                           0.50                Sand                   6.1                  2.9                 2                3.4
                           0.75                Sand                   5.9                  3.0                 2                3.2
                           2.00                Sand                   6.0                  2.9                 2                2.9
                           2.50                Sand                   6.0                  2.8                 2                3.1
                           2.75                Sand                   6.1                  2.8                 2                3.2
                           3.00                Sand                   6.0                  2.6                 2                3.3
Note: Reactivity numbers classify the reaction rate from 1 (slight) to 4 (extreme).

The results of the above table are presented graphically in the following figures. The pink zones in these figures
highlight which results indicate the possible presence of Actual ASS (AASS), the possible presence of Potential ASS
(PASS), and a significant change in pH as a result of oxidisation. The samples that were selected for follow up testing
are circled in red.


                                                      Field pH (pHF) measurements
                0


               0.5


                1
   Depth (m)




               1.5


                2


               2.5


                3
                     0     1      2       3        4         5        6         7     8           9   10       11       12    13      14
                                                                    Field pH (pH units)

Figure 7: Field pH test results. The pink zone (pH < 4) indicates the possible presence of Actual ASS (AASS).



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