Appendix H - Dewatering Management Plan · MCU25/0053

                                                                                                            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      (2000) Guidelines (per section 5.2 thereof) was superseded by the Guidelines for Managing Risks in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