ADG1304.21 Dewatering Management Plan_Rev1.1_17.12.24

                                                                                           ADG Consulting Pty Ltd


6.4.2 Dewatering strategy
      The Site Manager, Dewatering Contractor and ADG Consulting must formulate a dewatering strategy to
      ensure that the dewatering treatment system is sufficient to meet the requirements of the project and
      that the necessary equipment can be accommodated within the site prior to the commencement of
      dewatering.
6.4.3 Initial pump‐out
      Prior to discharge of any extracted groundwater to the canal system, the following pre‐dewatering
      procedure will be undertaken:

      1. The basement area will be excavated down to the standing groundwater level.
      2. The initial dewatering discharge will be directed (via the treatment systems) into the excavation and
         allowed to infiltrate/recharge the aquifer. This process will provide initial clarification of the extracted
         groundwater as disturbed sediment loads are typically reduced following the initial pump‐out.
      3. Samples of the treated groundwater will be recovered and analysed for the parameters detailed in
         Table 2 and Table 3.
      4. The extracted groundwater will be directed into the stormwater system following confirmation that
         the water quality complies with the discharge criteria.
6.5   Monitoring
6.5.1 Visual monitoring
      Visual inspections of the site and dewatering equipment shall be undertaken daily by the Site Manager
      to identify the following:
           Quantity of chemical product within the dosing system
           Effective operation of all dewatering treatment equipment
           Short circuiting of water around baffles and filter media in sediment tanks, where required to be
            installed.
           Visible hydrocarbon sheens and odours
           Green blue or extremely clear water indicating high levels of dissolved aluminium.
6.5.2 Water quality monitoring
      Water quality monitoring will be undertaken for the duration of dewatering activities at the site by a
      suitably qualified and independent person. The monitoring will include analysis of the extracted
      groundwater, treated discharge water and off‐site monitoring in the receiving waters (in the mixing zone
      within a 20 m radius of the discharge point). The exact location within the receiving waterway (Noosa
      River) is to be confirmed, however it is anticipated to be directly south/adjacent of the site. Background
      water quality monitoring of field parameters will also be conducted during each sampling event, if
      applicable. Background samples will be recovered from the river, either upstream or downstream from
      the receiving water location (tide dependant).

      The proposed monitoring locations are shown in Figure 1, Appendix A are a subject to confirmation
      following mobilisation of dewatering gear to site.

      Monitoring will be undertaken at the following frequencies:


           Daily monitoring of field parameters (pH, and turbidity) in the treated discharge water and pH of
            the untreated extracted groundwater (to determine potential acidification). Daily monitoring will
            be undertaken by a suitably trained site employee under the supervision of the Site Manager.
           Weekly monitoring of field parameters (pH, electrical conductivity, dissolved oxygen, temperature
            and turbidity) in the untreated extracted groundwater, treated discharge water, receiving waters
            and background waters by ADG Consulting.


 ADG1304.21 Dewatering Management Plan_Rev1.1_17.12.24                                                        Page 13