Table 4.8 Factors to be considered in a full risk assessment process Hazards Consider all hazards that do not pass the initial screening level of the risk assessment; key hazards are: boron • cadmium chlorine residuals phosphorus • • • chloride hydraulic loading salinity • • • nitrogen sodium Uses • • Consider the entry point of the hazard into the environment: Entry point Example cross-connection connection of recycled water systems with higher quality sources of – water (eg drinking water), producing a mixed supply backflow prevention device devices to prevent flow of recycled water into other water sources; this – may be most relevant for human health if the water source is a drinking water supply intentional allocation for the benefit of the environment, – discharge (intentional or • equipment maintenance, pressure release, cleaning of pipes; failure unintentional) of storage facilities or reticulation systems fire control controlling fires in urban environments – • irrigation watering roads to suppress dust, irrigation of crops, gardens and parks – • storage system holding recycled water before reticulation, or storage on a property – • before use washing streets, equipment, infrastructure – • Receiving environments and major endpoints Consider the initial receiving environment or endpoint (where the hazard potentially impacts on the environment): air toxicity • • biota aquatic waterlogging — • • biota terrestrial — • infrastructure • Effect Consider what the effect will be on: concentration • contamination • eutrophication • loss of biodiversity • plants • soils • water bodies groundwater or — • surface water nutrient imbalance • odour • pest and disease • salinity • recycled water treatment plant • or greywater reuse in-house sodicity •
Table 4.8 Factors to be considered in a full risk assessment process Hazards Consider all hazards that do not pass the initial screening level of the risk assessment; key hazards are: • boron • cadmium • chloride Uses • chlorine residuals • hydraulic loading • nitrogen • phosphorus • salinity • sodium Consider the entry point of the hazard into the environment: Entry point Example cross-connection – connection of recycled water systems with higher quality sources of water (eg drinking water), producing a mixed supply backflow prevention device – devices to prevent flow of recycled water into other water sources; this may be most relevant for human health if the water source is a drinking water supply • discharge (intentional or unintentional) – intentional allocation for the benefit of the environment, equipment maintenance, pressure release, cleaning of pipes; failure of storage facilities or reticulation systems • fire control – controlling fires in urban environments • irrigation – watering roads to suppress dust, irrigation of crops, gardens and parks • storage system – holding recycled water before reticulation, or storage on a property before use • washing – streets, equipment, infrastructure Receiving environments and major endpoints Consider the initial receiving environment or endpoint (where the hazard potentially impacts on the environment): • air • biota — aquatic • biota — terrestrial • infrastructure Effect Consider what the effect will be on: • concentration • contamination • eutrophication • loss of biodiversity • plants • soils • water bodies — groundwater or surface water • nutrient imbalance • odour • pest and disease • salinity • recycled water treatment plant or greywater reuse in-house • sodicity • toxicity • waterlogging