Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1:p3
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1 (pt 3/6)
Character Range: 2904064–2907023

short-term acute health risks, such as explosive or asphyxiation risks associated with the build-up of gases in a confined space, or the skin irritation risk associated with direct dermal contact with some soil contaminants
    * leaching of soil contamination into groundwater
    * health risks associated with the off-site migration of contaminants, for example, the contamination of potable groundwater supplies
    * health risks associated with exposure to soil contaminant vapours within a basement structure, or a structure where preferential pathways are present
    * other land use scenarios that are not adequately addressed in any of the generic land use scenarios (e.g. agricultural land)
    * consideration of aesthetic issues
    * risks to ecological receptors, for example, terrestrial or aquatic species.

    1.3.2         What does 'exceedence' of an HIL mean?
The potential for soil contaminant concentrations to vary significantly over a site means that a representative number of samples are required for an adequate understanding of the site. Recommendations regarding the sampling requirements for contaminated sites are described in Schedule B2.

Subject to the condition that site users are not identified as belonging to sensitive sub-populations, a site may be considered suitable for an intended land use provided that contaminant concentrations are less than the relevant HILs, with evidence from a sufficient number of samples and a spatially representative sampling design. In a situation where contaminant concentrations in some samples at a site exceed the HILs, statistical analysis may assist in the description and assessment of soil data in relation to the HILs.

HILs should only be used where there has been adequate characterisation of a site (that is, appropriate representative sampling has been carried out).

As a minimum, the maximum or 95% UCL should be compared to the HILs. However, where there is sufficient data and it is appropriate for the exposure being evaluated, the arithmetic mean (or geometric mean in the case of a log normal distribution) should also be compared to the HILs. The relevance of localised elevated values should be considered and should not be obscured by consideration only of the relevant mean of the results. The results should meet the following criteria:
    * the standard deviation (SD)of the results needs to be less than 50% of the HIL; and
    * no single value exceed 250% of the HIL.
However no single summary statistic will fully characterise a site and appropriate consideration of relevant statistical measurements should be used in the data evaluation process and iterative development of the CSM (refer to Schedule B2, Section 4). The preferred approach is to examine a range of summary statistics including the contaminant range, median, arithmetic/geometric mean, standard deviation and 95% UCL. Further information is provided in Section 11 of Schedule B2.

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