Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 4/6)
Character Range: 1184378–1187372

presented with justifications in the Preliminary ERA report.

4.4              Toxicity assessment
In a Preliminary ERA, it is assumed that the toxicity data and methods used to calculate the endorsed EILs are sufficiently protective of the general ecological system and biota at the site. However, where it is suspected that this is not the case (for example, certain threatened or endangered species need to be protected), a Definitive ERA should be undertaken. The basis for such a decision should be clearly presented with justifications in the Preliminary ERA report.

4.5              Risk characterisation
In a Preliminary ERA, risk characterisation consists of the comparison of on-site soil contaminant concentrations with the most appropriate EILs for the contaminants of concern.

If the on-site soil concentration of any contaminant of concern is equal to or less than the most appropriate EIL, then the site contamination is considered unlikely to be having an adverse impact on ecological values.

If the on-site soil concentration of any contaminant of concern is greater than the most appropriate EIL, the site contamination may be having an adverse impact on ecological values. Due to the general nature of data collected and the methods used to calculate EILs, the EILs are generally conservative. Therefore, levels of contamination above an EIL should not automatically necessitate remedial or clean-up action, but rather they trigger further evaluation.

The uncertainty associated with on-site soil concentrations (due to spatial heterogeneity both horizontally and vertically) and EILs and any conflicting results should be highlighted and discussed in the Preliminary ERA report.

If there is more than one contaminant of concern at the site then the risk posed by the combined effects of the contaminants should be assessed using the method set out in Appendix 2 of this Schedule.

It is important to consider the background concentration of contaminants of concern at the site or in sites with similar soil. If the most appropriate EIL for a contaminant of concern is lower than the background concentration, the background concentration becomes the EIL. It should be noted that this could only occur for EILs that are based on total concentrations rather than added concentrations[3].

4.6              Risk management decision and ERA outcomes
After risk characterisation, a risk management decision is necessary. This decision weighs up the findings of the Preliminary ERA against risk management considerations.
Factors that may influence a risk management decision (and therefore determine ERA outcomes) are generally based on economic, ecological or societal considerations as well as the scientific information and results generated within the Preliminary ERA. Examples include:
    * the size of the site, land value, and cost of remediation (economic)
    * the type of contaminants present, current and potential site land use, surrounding land use (societal)