Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p8
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 8/9)
Character Range: 939626–942400

maximum and the 95% UCL should be compared to relevant Tier 1 screening criteria. Where sufficient data is available it may be appropriate for the arithmetic mean (AM) to be compared to the relevant Tier 1 criteria. However, the implications of localised elevated values should also be considered. The results should also meet the following criteria:
    * the standard deviation (SD) of the results should be less than 50% of the Tier 1 screening criteria
    * no single value exceeds 250% of the relevant Tier 1 screening criteria.
No single summary statistic will fully characterise a site and a range of relevant statistical measurements should be considered in the data evaluation process and iterative development of the CSM (refer to Schedule B2, Section 4). It is preferable to examine a range of summary statistics including the contaminant range, median, geometric mean and geometric SD and 95% UCL as well as the AM and AM SD. Further information is provided in Schedule B2.

The end-point of the Tier 1 screening is the selection of the contaminants of potential concern that require further assessment. If the Tier 1 screening assessment concludes that there are no contaminants with plausible pathways to exposed populations, then the assessment is complete.

Further assessment after Tier 1 screening may comprise either additional assessment at Tier 2 (that is, risk assessment as described by the remainder of this guidance) or, alternatively, additional data collection may be required.

A weight-of-evidence approach, whereby the consistency of data from more than one line of evidence is considered, is recommended. For example, soil contamination at a site should also be evaluated by examining data from other media such as air, groundwater and surface water. This data should also be analysed in order for it to be used in the appropriate exposure scenario at a site. There is less guidance available on the characteristics of such data and indicators of its sufficiency. An initial review of these other types of data is required to determine if the sampling and analysis methods used were appropriate and if the detection limits achieved were appropriate given the risk-based screening criteria.

Groundwater data being used to assess human exposure may consider a reasonable maximum and relevant average at the site or off-site (as appropriate from the CSM). Where groundwater is to be extracted and used for any purpose, the suitability of groundwater data for the assessment of average and maximum exposures should be on a site-specific basis.

If air data or soil vapour data is available for the site, then the use of that data needs to be considered within the context of the CSM and the activities at the site that may affect the presence of