Table 4.5 Values used in Exposure Equation 9 to determine the percentage of contaminant in runoff water Variable Tier 1 Tier 2 Tier 3 Precipitation (mm/day). Bounding estimate rainfall The probability of Ψ To be determined. based on regional data. rain exceeding a Values between 1 and certain value 100 mm based on based on DSEWPaC (2009) and regional data will OECD (2000). be used as described in Section 3.4.2. R Runoff (mm/day). To Regional data on soil types Allow for be determined by the and hence curve numbers. variability of soil methodology described types within above (Section 3.4.2) region. and verified using ANRA (2001). Heterogeneity factor Bounding estimate Refined values 0.5 to 1 No change value of 1. based on Dunne and Black (1970), Kuhn and Zhu (2008). Retention factor Depending on release No change No change scenario 0.5 to 1 (Linders et al. 2000; Willis et al. 1994). Transportsuspended 0 for contaminants with % suspended sediment as No change contaminant water calculated by solubility 1 mg/L Release Equation 4. ≥ (Grover 1989). 20% or 12.5% 9%, 7.5% or 5% Allow for depending on scenario. (Balmer and Frey 2001; variability of OECD 2000) and available slopes within GIS data. region. Buffer Default Value 1 No change No change (No effect). DT50soil Assume no Use bounding estimate Use more likely degradation DT50 value. DT50 values, (DT50 = k = 0). such as the ∞; geometric mean or 95th percentile. Koc Assume no affinity for Use bounding estimate Use more likely soil (Koc = 0). Koc value. Koc values, such as the geometric mean or 95th percentile.
Table 4.5 Values used in Exposure Equation 9 to determine the percentage of contaminant in runoff water Variable Tier 1 Tier 2 Tier 3 Ψ Precipitation (mm/day). To be determined. Values between 1 and 100 mm based on DSEWPaC (2009) and OECD (2000). Bounding estimate rainfall based on regional data. The probability of rain exceeding a certain value based on regional data will be used as described in Section 3.4.2. R Runoff (mm/day). To be determined by the methodology described above (Section 3.4.2) and verified using ANRA (2001). Regional data on soil types and hence curve numbers. Allow for variability of soil types within region. Heterogeneity factor Bounding estimate value of 1. Refined values 0.5 to 1 based on Dunne and Black (1970), Kuhn and Zhu (2008). No change Retention factor Depending on release scenario 0.5 to 1 (Linders et al. 2000; Willis et al. 1994). No change No change Transportsuspended contaminant 0 for contaminants with water solubility ≥ 1 mg/L (Grover 1989). % suspended sediment as calculated by Release Equation 4. No change 20% or 12.5% depending on scenario. 9%, 7.5% or 5% (Balmer and Frey 2001; OECD 2000) and available GIS data. Allow for variability of slopes within region. Buffer Default Value 1 (No effect). No change No change DT50soil Assume no degradation (DT50 = ∞; k = 0). Use bounding estimate DT50 value. Use more likely DT50 values, such as the geometric mean or 95th percentile. Koc Assume no affinity for soil (Koc = 0). Use bounding estimate Koc value. Use more likely Koc values, such as the geometric mean or 95th percentile.
technical-report-number-09-environment-exposure-conceptualisation.docx