Reference Document - Acid Sulfate Soil Report 11_2023- OPW23_0189 · OPW26/0094

                                                                                                               ADG Consulting Pty Ltd



                               Laboratory analysis of samples recovered from   Initially, then as                      Environmental
                                                                                                    ADG Consulting
                               extracted groundwater (pre‐treated)                 required                              Consultant

                      6.6     Maintenance
                              The groundwater treatment systems must be regularly maintained. Maintenance must include:
                                  Regular cleaning and or replacement of the filters within the filtration unit, where required to be
                                   installed.
                                  Regular removal of sediment from the sedimentation tank. The sediment must be either returned
                                   to the excavation pit for dewatering and bulking out with excavated material, or removed from the
                                   site by a licensed liquid waste contractor.
                                  Regular check of the dosing system and top‐up of buffering solutions and flocculants.
                      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



                        ADG1580.23 Dewatering Management Plan_Rev0_28.09.23                                                     Page 15




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