Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 9/9)
Character Range: 942200–943231

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 the chemicals in the air. Consideration of both a reasonable maximum and a relevant average case should be developed where possible.

Data generated from chemical analyses may fall below the limit of detection (LOD) or limit of reporting (LOR) for the analytical procedure. Although substitution methods (such as replacing with the LOD/2) are reported widely in the literature for analysing data with non-detects, these approaches result in bias of summary statistics calculated from the adjusted data set. Where less than about 15% of the relevant data set comprises non-detects, substituting half the detection limit may be satisfactory (US EPA 2006). More detailed adjustments may be appropriate where greater than 15% of results are below detection. Further information can be found in Schedule B2 and US EPA (2006 and 2007a).