Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:5:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 5 (pt 1/5)
Character Range: 1190642–1194120

5                   Definitive ecological risk assessment
Generally, a Definitive ERA is only commenced once a Preliminary ERA has been conducted and has demonstrated that the contaminants present at the site pose a potential ecological threat. This iterative procedure allows each tier of ERA to be reviewed to determine whether the assessment is meeting the objectives set and to establish what the next phase should be.

This section provides guidance on how to conduct a Definitive ERA (see Figure 4 below). In a Definitive ERA, the focus is on quantifying exposure levels through field studies and the use of sophisticated computer models. Emphasis is placed on gathering detailed, site-specific information as part of the receptor identification, exposure assessment and toxicity assessment. A summary of data that may be collected as part of a Definitive ERA is included in Table 3.

Based on site-specific information, site-specific EILs for soil are derived. The comparison of the on-site soil concentrations of contaminants of concern against the site-specific EILs characterises the ecological risk at the site and influences any outcomes.

Figure 4. Definitive ERA

Table 3. Information that may be collected for each component of a Definitive ERA.
ERA component            Indicative requirements for a Definitive ERA
Problem identification   Refined objectives and updated CSM based on information in the Preliminary ERA
                         Identification of contaminants of concern (including mixtures and contaminant form) that exceed EILs
                         Formulation of the assessment end point, e.g. will the assessment end point be based on species abundance; growth rates, frequency of chlorosis or necrosis in plants; or failure to develop?
Receptor identification  Flora and fauna surveys of the site and surrounding area
                         Identification of species of concern, including threatened and endangered species
                         Ecosystem function and ecosystem interaction established
                         Confident that the interface between biological monitoring plans and previous risk assessment is sufficiently robust to improve the risk assessment?
Exposure assessment      Fate and transport modelling of contaminants of concern
                         Species-specific inhalation, ingestion and absorption rates
                         Identification of on-site soil properties that affect contaminant mobility/availability (e.g. organic carbon content, pH, bulk density, porosity, soil moisture)
                         Bioavailability factors
                         Sampling and analysis of food, water and air for effects of contamination
                         Information on biota behaviour relevant to assessing exposure
Toxicity assessment      Detailed literature review of relevant toxicological studies since the EILs were derived
                         Results of in situ field or laboratory toxicity tests
Risk characterisation    Information on chemical mixtures, concentration of contaminants of concern (derived from problem identification)

5.1              Problem identification
When commencing a Definitive ERA, it is important to reconsider the objectives that were used for the Preliminary ERA, taking into account the results of the Preliminary ERA. If appropriate, new objectives should be identified.
The main objectives for a Definitive ERA should be to:
    * identify