Dewatering Management Plan · OPW24/0032

                                                                                        ADG Consulting Pty Ltd


6.7 Reporting
     Dewatering management procedures and monitoring results will be reviewed by ADG Consulting weekly
     to ensure that the treatment procedures are effective, and that the receiving waters are not being
     impacted by the extracted groundwater being discharged.

     The following reporting procedures will be adopted:
          A summary report will be prepared upon completion of the initial pre‐discharge monitoring. The
           report will be submitted to the Site Manager, Dewatering Contractor, and NSC upon request.
          Weekly interim reports will be prepared upon receipt of laboratory data for each round of ongoing
           compliance monitoring. The interim reports will display all data obtained during the previous
           monitoring event, and provide comments and recommendations based on the results.
          A dewatering compliance report will be prepared on completion of the project (upon request).
     The above reports will be prepared by ADG Consulting and provided to the Site Manager and Dewatering
     Contractor as they become available. The reports will include all water quality results and comparison to
     the WQOs, corrective actions and recommendations made to the Site Manager and Dewatering
     Contractor during the monitoring period.

     The Site Manager must keep records of complaints, volumes of chemicals used and treatment methods
     employed. These records must be available on‐site at all times and submitted to NSC by the Site Manager
     upon request.
6.8 Contingencies
     If water quality monitoring indicates ongoing exceedances of the performance criteria, and the water
     quality objectives for the receiving waters cannot be met, then corrective actions will be adopted as
     necessary. Possible contingencies may include one or more of the following:
          Installation of additional sedimentation tanks to provide increased residence time and assist with
           the retention of precipitated iron hydroxides, other heavy metals and/or suspended sediments.
          Installation of additional flocculant and/or coagulant dosing systems to assist in precipitation of
           suspended sediments and/or heavy metals.
          Installation of activated carbon filtration or other fine media filtration to retain suspended
           sediments and/or heavy metals.
          Install a floating sediment curtain/s around the stormwater termination point in the receiving
           waterway to prevent unsightly plumes and contain sediment and/or heavy metals for periodic
           removal (subject to approval by Noose Shire Council).
          Preventive and corrective actions shall be taken in the event that groundwater monitoring
           observations indicate that unexpected groundwater contamination has been encountered during
           dewatering. The most appropriate action(s) shall be dependent on the stage of construction and
           risk of adverse impacts to groundwater users and the receiving environment.
          Any modification to the dewatering system and pumping rates shall be in consultation with a
           suitably qualified scientist/geotechnical/engineer.
          Following heavy rainfall all ponded surfaces waters are to meet discharge criteria (Table 3) prior to
           offsite discharge. Where discharge criteria not met, Site Manager to obtain approval from
           Dewatering Contractor regarding treating surface waters with treatment gear before offsite
           discharge.
          Pumping systems and shoring works to be maintained in fit for purpose state by Dewatering
           Contractor and/or shoring contractor. In the event that dewatering equipment has failed and is
           likely to cause a significant impact on the environment, or surrounding properties (i.e. flooding) the
           Dewatering Contractor is to be contacted immediately. The Principal Contractor, in consultation
           with the Dewatering Contractor shall be responsible in rectifying the failure in a practicable time


ADG1304.21 Dewatering Management Plan_Rev0_08.10.21                                                       Page 15