ADG1304.21 Dewatering Management Plan_Rev1.1_17.12.24

                                                                                         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_Rev1.1_17.12.24                                                     Page 15