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

                                                                                                                                    ADG Consulting Pty Ltd

                              guideline values are triggers to further action, are inherently conservative, and that the response to non‐
                              compliance should match the magnitude and impacts (if any) of the exceedance.

                              Section 5 (Guidelines for recreational water quality and aesthetics) of the previous ANZECC/ARMCANZ
                              (2000) Guidelines (per section 5.2 thereof) was superseded by the Guidelines for Managing Risks in
                              Recreational Water in 2008 (NHMRC, 2008). Therefore, a reference to the ANZECC/ARMCANZ
                              (2000)/ANZG (2018) Guidelines is by association and extension a reference to the current 2008 NHMRC
                              Guidelines. The 2008 NHMRC Guidelines contain no criteria for aluminium, and only includes an aesthetic
                              criterion for iron – noting this is an aesthetic criterion derived from the Australian Drinking Water
                              Guidelines on the basis of ingesting 2L of the recreational water solution per day. ANZECC/ARMCANZ
                              (2000) Section 5.2.3.3, notes that as a general guideline, under Toxic Chemicals, ‘Higher concentrations
                              of toxicants may be tolerated occasionally if it assumed that no person will ingest more than a maximum
                              of 100 mL water during a normal swimming session (NHMRC 1990) compared with 2L/d for potable
                              water’, and Section 3.1.1.3, under Risk based approach of the guidelines, ‘The guideline trigger values are
                              based on bioavailable concentrations, and hence are relatively conservative when compared with total
                              concentrations in the field, so the use of the decision frameworks will increase guideline concentrations
                              in most cases’. Therefore, any chemical toxicant trigger values would require reassessment and likely
                              increase upwards of any ANZECC/ARMCANZ (2000)/ANZG (2018) Guideline trigger values due to the
                              slightly to moderately disturbed nature (and thereby reduced sensitivity) of the receiving waters.

                              Regardless of the WQOs adopted in this DMP, the General Environmental Duty set out in the EP Act is
                              paramount, which requires that “a person must not carry out an activity that causes or is likely to cause
                              environmental harm unless the person takes all reasonable and practicable measures to prevent or
                              minimise the harm”.
                      4.3     Proposed water quality objectives
                              The proposed water quality objectives that have been developed for the discharge of extracted
                              groundwater from the site are provided in the Tables below. All water discharged from the site must
                              comply with the discharge criteria provided in Table 2. Additionally, the receiving water quality within a
                              20m radius of the discharge point (the receiving waters mixing zone) shall comply with the receiving
                              water criteria provided in Table 3. Receiving waters data will be assessed against background monitoring
                              data if non‐compliant results are obtained at the receiving waters monitoring location.

                              Table 2 Discharge criteria

                                                         Parameter                                                            Criteria

                               Physico‐chemical

                               pH (pH units)                                                                                6.5 – 8.51,2

                               Dissolved oxygen (% saturation)                                                                 >802

                               Suspended solids (mg/L)                                                                         <501,2

                               Turbidity (NTU)                                                                                 <502

                               Litter/visible plumes                                                  None visible at the point of discharge or in a waterway

                               Total metals (µg/L)

                               Aluminium                                                                                       2003

                               Iron                                                                                            3003

                              Table notes:

                              1. QWQG 2009 (2013) Refer to Table 8.2.1. Summary of design objectives for management of stormwater quality and flow – construction
                                 phase of development in Queensland.
                              2. Typical discharge criteria recognised throughout QLD.
                              3. SCC (2008). Water release criteria as specified in the SCC Manual for Erosion and Sediment Control, Chapter 6.




                        ADG1777.25 Dewatering Management Plan_Rev0_01.05.25                                                                               Page 7




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