Table 5.10 Criteria, controls and monitoring to mitigate organic chemical hazards in relation to the stages of risk assessment chemicals unlikely in risk assessment concentrations that source water at meet environmental Any organic • concentrations that values for aquifer chemicals present in would exceed acceptable beyond attenuation source water (eg Acceptance concentrations for zone and in water using mean of criteria environmental values of recovered for use measured aquifer or intended end concentrations to uses Entry-level account for Residual risk Unlikely to be formed in assessment • dispersiona in aquifer) assessment the subsurface (ie no and or formed in the (operational) disinfection) simplified subsurface (eg As per • assessment disinfection precommissioning Maximal and byproducts) are at, or residual risk precommissioning residual attenuate to, Organic assessment • Preventive residence time in soil measures or aquifer, or treatment na Source control Reduce disinfection • • byproduct precursors • or change the disinfection process P As per precommissioning residual risk • assessment (hazard) Validation and biodegradable monitoring organic carbon (cosubstrate) concentrations in source water – attenuation zone – observation well/s recovered water – Analyse minimum • • period of aquifer storage using D or e ‘natural’ t introduced tracers Evaluate • physicochemical and redox m conditions
Table 5.10 Criteria, controls and monitoring to mitigate organic chemical hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Organic chemicals unlikely in source water at concentrations that would exceed acceptable concentrations for environmental values of aquifer or intended end uses • Unlikely to be formed in the subsurface (ie no disinfection) Maximal and precommissioning residual risk assessment • Any organic chemicals present in source water (eg using mean of measured concentrations to account for dispersiona in aquifer) or formed in the subsurface (eg disinfection byproducts) are at, or attenuate to, concentrations that meet environmental values for aquifer beyond attenuation zone and in water recovered for use Residual risk assessment (operational) • As per precommissioning residual risk assessment Preventive measures na • Source control • residence time in soil or aquifer, or treatment • Reduce disinfection byproduct precursors or change the disinfection process • As per precommissioning residual risk assessment Validation monitoring • (hazard) and biodegradable organic carbon (cosubstrate) concentrations in – source water – attenuation zone observation well/s – recovered water • Analyse minimum period of aquifer storage using ‘natural’ or introduced tracers • Evaluate physicochemical and redox conditions m P t e D
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