RESPONSE TO FURTHER ADVICE - ADG1808.25 Dewatering Management Plan_Rev0_07.05.25 · MCU25/0054

                                                                                                                  ADG Consulting Pty Ltd




     Table 3 Receiving waters criteria

                                  Parameter                                                              Criteria

      Physico‐chemical

      pH (pH units)                                                                                     7.8 – 8.31

      Dissolved oxygen (% saturation)                                                                   85 – 1051

      Suspended solids (mg/L)                                                                              ≤141

      Turbidity (NTU)                                                                                      ≤61

      Dissolved metals (µg/L)

      Aluminium                                                                           No relevant ANZG criterion available

      Arsenic                                                                            No relevant ANZG criterion available*

      Cadmium                                                                                              5.52

      Chromium                                                                                             4.42

      Copper                                                                                               1.32

      Iron                                                                                No relevant ANZG criterion available

      Lead                                                                                                 4.42

      Nickel                                                                                               702

      Zinc                                                                                                  82

      Mercury                                                                                              0.42

      Total metals (µg/L)

      Aluminium                                                                                   No ANZG criteria / 2003

      Iron                                                                                        No ANZG criteria / 3003

     Table notes:

     1. DES (2022). Noosa River environmental values and water quality objectives (moderately disturbed – Noosa River – canals and marinas).
     2. ANZG (2018) – Marine water trigger values for 95% species protection (Supersedes ANZECC/ARMCANZ (2000)).
     3. Criteria subject to expected condition in Development Application (DA) notice by Noosa Shire Council.

     Although ADG has not been provided a copy of any DA notice or conditions for the proposed development
     (not yet available at the time of writing), based on previous dewatering projects in the Noosa Coast
     Region it is expected that total iron and aluminium concentrations as listed in Table 3 (above) are likely
     to be conditioned by Noosa Shire Council for compliance. It should be noted that these concentrations
     are considered to be onerous with respect to the risk‐based (worst‐case) bioavailable trigger value criteria
     contained in ANZG 2018 & ANZECC/ARMCANZ (2000) for marine water (moderately disturbed) 95%
     species protection, and are likely to be difficult to achieve given the groundwater conditions encountered
     in the locality on previous dewatering projects on the Noosa Coast.

     Prior to discharge to the stormwater system or any waterway, discharges are to be tested to meet the
     requirements of the ANZG 2018 & ANZECC/ARMCANZ (2000) Guidelines for Fresh and Marine Water
     Quality. There is currently no chemical toxicant trigger value criteria available for total or dissolved (i.e.
     bioavailable) concentrations of aluminium or iron for marine or estuarine waters under the Australian
     and New Zealand Guidelines for Fresh and Marine Water Quality Guidelines (ANZG 2018 &
     ANZECC/ARMCANZ 2000 – i.e. ANZECC Guidelines) or the Guidelines for Managing Risks in Recreational
     Waters (NHMRC 2008), with regards to managing environmental impacts to the waterway.

     In addition, Section 5 (Guidelines for recreational water quality and aesthetics) of the 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)

ADG1808.25 Dewatering Management Plan_Rev0_07.05.25                                                                                   Page 8