Reference Document - Acid Sulfate Soil Management Plan (For Stamping) MCU25/0053 & OPW25/0074

        Groundwater               guidelines, refer to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality
        (continued):              (ANZECC and ARMCANZ, 2000).

                                  The groundwater should be monitored before, during, and after earthworks have been completed,
                                  based on the following test criteria:-

                                  »    Groundwater testing should be carried out before the earthworks begin to establish baseline
                                       testing values for groundwater level, pH, Electrical Conductivity, aluminium content and iron
                                       content. Pre-development ‘baseline’ values should be recorded by a suitably qualified and
                                       competent consultant as close as possible to, and before the first day of earthworks.
                                  »    Groundwater will be required to be monitored for groundwater level, pH, Electrical Conductivity,
                                       aluminium content and iron content during the earthworks period, and prior to discharge from the
                                       site.
                                  »    A groundwater sample should be obtained by a suitably qualified and competent groundwater
                                       consultant as soon as possible after the earthworks period has been completed to monitor any
                                       change in the groundwater level, pH, Electrical Conductivity, aluminium content and iron content.
                                  »    Groundwater pH should be monitored on daily basis and prior to discharge, and range between
                                       pH 6 and pH 8 (‘National Acid Sulfate Soils Guidance – National acid sulfate soils sampling and
                                       identification methods manual, June, 2018’, Australian Government, 2018), unless an assessment
                                       by a suitably qualified and competent groundwater consultant deems there to be an alternative
                                       ‘natural/baseline’ range which can be used.
                                  »    Electrical Conductivity (EC) should be monitored on a daily basis and prior to discharge, and
                                       should be less than 520 µS/cm (QLD DEHP, 2013).
                                  »    Dissolved and Total Aluminium (Al) content monitored on a weekly basis and prior to discharge,
                                       and should be less than 0.055 mg/L (ANZECC and ARMCANZ, 2000).
                                  »    Dissolved and Total Iron (Fe) content monitored on a weekly basis and prior to discharge, and
                                       should be less than 0.3 mg/L (ANZECC and ARMCANZ, 2000).
                                  »    It is recommended that a suitably qualified and competent groundwater consultant be contacted
                                       for further information on groundwater testing, monitoring and any treatment requirements
                                       before earthworks are carried out on the site, and where the groundwater test results do not meet
                                       the required test criteria.
                                  »    Specific groundwater monitoring criteria may need to be achieved to satisfy Noosa Shire Council
                                       before water is discharged offsite and this should be checked.
                                  »    Specialist, competent and suitably qualified groundwater consultants should be contacted prior
                                       to the proposed earthworks and any dewatering.
                                  »    As a precaution, excess agricultural lime should always be kept as a standby measure to treat any
                                       acidic groundwater produced during earthworks. Hydrated lime is not recommended for
                                       groundwater treatment, as this material can have adverse effects on water such as producing
                                       highly alkaline groundwater with pH levels greater than pH 9 or pH 10. A suitably qualified and
                                       competent groundwater consultant should be contacted should groundwater pH or other
                                       groundwater monitoring test results suggest that groundwater treatment is required.
        Monitoring:               Three phases of Acid Sulfate Soil testing will be undertaken:

                                  »    Phase 1 – In-situ testing (completed).
                                  »    Phase 2 – Groundwater level and pH monitoring before, during and after earthworks (where
                                       required), and
                                  »    Phase 3 – Validation testing of lime-treated material.

                                  Areas exposed during the development shall be monitored daily for evidence of iron staining of soils
                                  and water, yellow efflorescence on soil surface, sulfurous odours (“rotten egg gas”) and low soil pH.

                                  Once the soil excavated as part of the proposed earthworks below RL 5 m AHD is lime treated at the
                                  required rates, a suitably qualified and competent environmental or geotechnical consultant is to be
                                  contacted to ensure validation sampling and testing of the lime treated soil is carried out. This process
                                  ensures that the lime has been thoroughly mixed through the Acid Sulfate Soil and that the acidity has
                                  been neutralised. Once the lime treated soil is validated, it may be transported or used offsite, subject
                                  to further contamination, geotechnical or other quality testing as required.

                                  Refer to the ‘Validation’ section of this ASSMP for further information on validation testing.

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Document Set ID: 24149759
Version: 1, Version Date: 26/09/2025