Table 5.6 Criteria, controls and monitoring to mitigate inorganic chemical hazards in relation to the stages of risk assessment chemistry chemical concentrations (operational) concentration meets in source water meet the environmental target for beneficial use As per • target for the aquifer Decision tree in Appendix 7 • precommissioning Acceptance Low risk of suggests metal mobilisation is • residual risk criteria unlikely to be a problem mobilisation from assessment the aquifer Geochemical modelling • shows release from aquifer is Entry-level unlikely to produce inorganic assessment Maximal and chemical concentrations and precommissioning above target values simplified residual risk assessment assessment Residual risk assessment Major ion Inorganic • • to Sections 6.1 and 6.2 for Preventive operational management measures pH and redox (Eh) • adjustment in source water As per precommissioning residual risk • assessment, plus • source control – R treatment of source water to minimise release – from aquifer post-treatment of recovered water – inorganic Validation chemical monitoring concentrations in source water – groundwater in – storage zone (observation well/s) recovered water – Evaluate aquifer • physiochemical and • redox conditions D e t chemical Verification concentrations in monitoring recovered water and at margin of attenuation i zone Not • applicable at n project scale (undertaken at regional scale) • D e
Table 5.6 Criteria, controls and monitoring to mitigate inorganic chemical hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Major ion chemistry concentration meets the environmental target for the aquifer • Low risk of mobilisation from the aquifer Maximal and precommissioning residual risk assessment • Inorganic chemical concentrations in source water meet target for beneficial use • Decision tree in Appendix 7 suggests metal mobilisation is unlikely to be a problem • Geochemical modelling shows release from aquifer is unlikely to produce inorganic chemical concentrations above target values Residual risk assessment (operational) • As per precommissioning residual risk assessment Preventive measures • to Sections 6.1 and 6.2 for operational management • pH and redox (Eh) adjustment in source water • As per precommissioning residual risk assessment, plus – source control – treatment of source water to minimise release from aquifer – post-treatment of recovered water Validation monitoring • inorganic chemical concentrations in – source water – groundwater in storage zone (observation well/s) – recovered water • Evaluate aquifer physiochemical and redox conditions Verification monitoring • Not applicable at project scale (undertaken at regional scale) • chemical concentrations in recovered water and at margin of attenuation zone R t e e n i D D
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