Reference Document - Dewatering Management Plan (For Stamping) MCU25/0053 & OPW25/0074

                                                                                                                  ADG Consulting Pty Ltd

                              Tertiary treatment (if required) – may be required following initial testing of extracted groundwater
                              A specialised fine media filtration system designed for the effective removal of both total and dissolved
                              forms of heavy metals, with particular specific retention of iron and aluminium, will be utilised to remove
                              heavy metals from the secondary treated groundwater prior to discharge to the stormwater system. The
                              system will be capable of backflushing on manual or automated basis with retained concentrated heavy
                              metal suspended solids diverted to a backflush tank for further settling/thickening prior to offsite removal
                              by licenced liquid waste contractor for lawful disposal at a licenced disposal facility. 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 will, if practicable, 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 the 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, or as soon as practicable following the initial, 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. Note: ADG must be provided reasonable notice in order for this step to be
                                   undertaken.
                              4.   The extracted groundwater will be directed, or recommended to continue discharge, into the
                                   stormwater system following confirmation that the water quality complies with the discharge
                                   criteria. Or other recommendations will be provided, as required.
                      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, experienced and independent person. The monitoring will include analysis of the

                        ADG1777.25 Dewatering Management Plan_Rev0_01.05.25                                                        Page 14




Document Set ID: 23735664
Version: 1, Version Date: 12/05/2025