4.
MMM groundwater monitoring results analysis
4.1 Monitoring completed Monitoring was completed on a monthly basis from August 2022 to September 2024 from the network specified in the EA with the following exceptions: – No monitoring was completed from MB3. GHD understand that MB3 was dry and unable to be monitored. Monitoring was completed from MB4-D and MB11 in place of MB3. – Monitoring was completed from MB4-D during August 2022 to March 2023 (six events), and for MB11 from April 2023 to September 2024 (18 events). GHD understands that MB4-D was initially monitored in place of MB3, with MB11 replacing MB4-D in the latter stages of the program as MB4-D became unreliable. 4.2 Groundwater quality 4.2.1 Overview Groundwater monitoring data collected between August 2022 and September 2024 has been assessed to characterise groundwater quality in relation to published water quality guidelines listed in Section 3.3. The results are discussed in the following sections, with supporting information provided as follows: – Tabulated groundwater chemistry results are presented in Appendix A. – Time-series groundwater chemistry charts displaying monitoring results are presented in Appendix B – Time-series groundwater chemistry charts displaying monitoring results with published water quality guideline values are included in Appendix C. – Results from the Mann-Kendall trend analysis are summarised and displayed in Appendix D. – Laboratory documentation is presented in Appendix E. 4.2.2 Assessment approach The assessment focuses on the indicator analytes listed in EA Condition W8, which are outlined in Section 3.1. Groundwater monitoring results were provided to GHD by Heritage Minerals, in the form of lab reports directly from the ALS. GHD understand that field measurements of pH and EC were not collected. The assessment approach involved assessing: – Comparison of groundwater quality results against published water quality guidelines. – Assessing groundwater quality results for trends. Trend analysis was completed utilising a Mann-Kendall statistical test. The Mann-Kendall trend analysis is summarised in Section 4.2.4. Time-series charts for trending analytes are presented in Appendix D. 4.2.3 Water quality guidelines exceedance results Groundwater concentrations for each monitoring location were compared against published water quality guidelines values (ANZG 2018), as outlined in Section 3.3. Exceedance graphs are presented in Appendix C and results summarised in Table 4.1.
GHD | Heritage Minerals Pty Ltd | 12638246 | Groundwater Quality Review 2024 17
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