At this stage, a watching brief should be included in reviews of the risk assessment completed for recycling water. These national guidelines should also be updated or amended as ongoing research in Australia and elsewhere leads to a better understanding of the impacts of EDCs. More information on the current state of our knowledge of EDCs can be found on the websites of the WHO7 and the Water Environment Research Foundation.8 Estimate likelihood of hazardous event occurring Table 2.5 in Chapter 2 describes qualitative measures of likelihood. This step involves estimating the likelihood that an environmental endpoint will be exposed to the hazard in sufficient concentrations to cause a detrimental effect; a step that requires adequate information and suitable expertise. The descriptors and definitions outlined in Table 2.5 (Chapter 2) are then used to rate the likelihood of an event occurring. Likelihood of exposure to the environmental endpoint can often be determined by previous experience documented in reports (eg pipe bursts per year, tank leakage in other systems, cross- connections in other reuse schemes) or from professional opinion. For example, qualitatively, the likelihood of watering a lawn with recycled water is in Table 2.5). To assess ‘almost certain’ (E the likelihood of a main pipe bursting, it is necessary to check the age of the pipe and what it is made from, and compare that information with major pipe bursts identified from records kept within the relevant water authority. If the age and construction of the pipe are similar to those involved in major bursts, then the assessment may be that the likelihood is in ‘possible’ (C Table 2.5). To assess the likelihood that a selected environmental endpoint will be exposed to concentrations sufficient to cause a detrimental effect, the concentration or total load of the hazard will need to be calculated and compared with known guideline values (these guideline values will be used to set the target criteria or critical limits discussed in Section 2.3.2). Estimate consequences of hazardous event occurring Table 2.6 in Chapter 2 describes qualitative measures of consequences or impact. This section describes how to determine the consequences (or impact) of exposure to a hazard by considering: the size and nature of the environmental population exposed to the hazard (ie specific • endpoints) the route, amount and duration of exposure. • The impact should be put into an environmental context by using Table 4.4 (below) to help determine, qualitatively, what the impact is. See 7 See 8
At this stage, a watching brief should be included in reviews of the risk assessment completed for recycling water. These national guidelines should also be updated or amended as ongoing research in Australia and elsewhere leads to a better understanding of the impacts of EDCs. More information on the current state of our knowledge of EDCs can be found on the websites of the WHO7 and the Water Environment Research Foundation.8 Estimate likelihood of hazardous event occurring Table 2.5 in Chapter 2 describes qualitative measures of likelihood. This step involves estimating the likelihood that an environmental endpoint will be exposed to the hazard in sufficient concentrations to cause a detrimental effect; a step that requires adequate information and suitable expertise. The descriptors and definitions outlined in Table 2.5 (Chapter 2) are then used to rate the likelihood of an event occurring. Likelihood of exposure to the environmental endpoint can often be determined by previous experience documented in reports (eg pipe bursts per year, tank leakage in other systems, cross- connections in other reuse schemes) or from professional opinion. For example, qualitatively, the likelihood of watering a lawn with recycled water is ‘almost certain’ (E in Table 2.5). To assess the likelihood of a main pipe bursting, it is necessary to check the age of the pipe and what it is made from, and compare that information with major pipe bursts identified from records kept within the relevant water authority. If the age and construction of the pipe are similar to those involved in major bursts, then the assessment may be that the likelihood is ‘possible’ (C in Table 2.5). To assess the likelihood that a selected environmental endpoint will be exposed to concentrations sufficient to cause a detrimental effect, the concentration or total load of the hazard will need to be calculated and compared with known guideline values (these guideline values will be used to set the target criteria or critical limits discussed in Section 2.3.2). Estimate consequences of hazardous event occurring Table 2.6 in Chapter 2 describes qualitative measures of consequences or impact. This section describes how to determine the consequences (or impact) of exposure to a hazard by considering: • the size and nature of the environmental population exposed to the hazard (ie specific endpoints) • the route, amount and duration of exposure. The impact should be put into an environmental context by using Table 4.4 (below) to help determine, qualitatively, what the impact is. 7 See 8 See
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