RFI - Ecological Assessment Report

EMP – CONSTRUCTION PHASE                                                                                    4-32

       Strategy:        Identify any Acid Sulphate Soils which may be disturbed and develop appropriate
                        management plan to prevent or minimise any impacts associated with the
                        occurrence of Acid Sulphate Soils (ASS).
              excavating trenches, laying pipe and backfilling with excavated material as quickly as possible.
              To this end no more than 10m of trench extending below 5.0m AHD shall be left unbackfilled at
              any one time.
        4.    All trenches must be backfilled with excavated material prior to cessation of a day’s work.
        5.    Trenching below RL 5.0m AHD shall not take place when there is a high risk of rainfall.
        6.    Any residual material excess to the backfill will be tested and treated as required and disposed of
              to a location agreed to with the Council. Residual material to be stored in a bunded area, treated
              with agricultural lime at a rate of 5kg/m2 until disposed of.
        7.    Trench dewatering (if required) shall be effected using a submersible pump at the base of the
              excavation with shields installed to limit inflow and slumping.
        8.    Discharge from dewatering operations shall be impounded in a holding tank of sufficient size for
              the purpose.
        9.    Impounded water shall be tested and treated with hydrated lime to bring the pH to between 6.5
              and 8.5 if necessary. Lime shall be added as a slurry, using appropriate equipment and pH
              monitoring shall take place continuously during this process to ensure that overshooting of
              neutral pH does not occur. The Contractor shall provide adequate mixing within the holding
              tank during the neutralization process by mechanical means in necessary.

       10. All impounded waters shall be tested and verified as achieving prescribed pH range. No water is
           to be discharged to adjacent wetland areas due to potential effects on the pH of the heathland,
           reflecting the presence of organic acids as opposed to mineral acids from acid generation. With
           this is the need to consider consequent effects on wallum froglets. Water from the holding tank
           is, as a consequence, to be discharged to an infiltration area approved by the EPA in consultation
           with Council.

       Performance Requirement: Compliance with the provisions of State Planning Policy 2/02 –
       Planning and Managing Development involving Acid Sulphate Soils. No environmental impacts from
       acid sulphate soils.

       Monitoring: Compliance with the provisions of State Planning Policy 2/02 – Planning and Managing
       Development involving Acid Sulphate Soils.

       The works shall be monitored on a daily basis for evidence of:
        1.    yellow efflorescence on soil surface;
        2.    sulphurous odour;
        3.    scalding, degradation or death of vegetation;
        4.    the formation of the mineral jarosite in exposed soils;
        5.    areas of blue-green water or extremely clear water.

       Reporting: Site Environmental Officer to include test results confirming treatment of any ASS in

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