003 ECM_22828362_v1_Reference Document - OPW23 0189 · OPW26/0094

                                                                                                                    ADG Consulting Pty Ltd


                              precipitated and retained within the sedimentation tank/s (secondary treatment). This treatment system
                              will provide tertiary treatment of the groundwater prior to offsite discharge. This type of fine media
                              filtration treatment system is a forced‐flow system under pressure, and generally capable of treating flow
                              rates of up to 20 L/sec per filtration unit (therefore residence time is inconsequential to treatment quality
                              achieved).

                              Tertiary treatment will only be required if the required water quality is unable to be achieved following
                              primary and secondary stages of treatment. Subject to the results of field and laboratory testing during
                              the pre‐discharge monitoring event.


                      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.

                              Where construction of the proposed development requires occupation of the road reserve (verge area
                              and/or road formation) for either short term or long term, a road reserve permit must be obtained from
                              Council prior to any occupation of the road reserve.
                      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 canal) is to be confirmed, however it is anticipated to be directly north/adjacent of the site.
                              Background water quality monitoring of field parameters will also be conducted during each sampling



                        ADG1580.23 Dewatering Management Plan_Rev0_28.09.23                                                           Page 13




Document Set ID: 22828362
Version: 1, Version Date: 26/02/2024