Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p24
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 24/117)
Character Range: 412761–415753

lamp to ionise the vapours. The instrument response is related to the electric current generated by the ionised compounds. FIDs are most sensitive to aliphatic hydrocarbons as these compounds burn more efficiently than aromatic compounds. PID instruments are most sensitive to aromatic hydrocarbons (for example, BTEX compounds) and can measure most VOCs in the range of C6 equivalent carbon atoms (for example, benzene) to C10 (for example, naphthalene). Neither instrument is effective for detecting non-volatile compounds such as highly weathered hydrocarbons. Care should be taken when using PIDs since a positive bias may result from water vapour or moist air and/or dust being drawn into the instrument. FIDs are not sensitive to water vapour.

A standardised field procedure for headspace testing should be followed and the details of the test method documented (size of jar, soil volume, equilibration time and ambient temperature) in the investigation report.

    7.4.4          Field portable x-ray fluorescence
X-ray fluorescence (XRF) is a rapid screening tool that can be used to measure metal concentrations in soil. Performance is dependent on the metal, the soil matrix and soil moisture content. Although a range of heavy metals can be simultaneously detected, there are potential interferences that influence the method accuracy and precision. The US EPA has developed a methodology to guide XRF analysis (US EPA 2007b).

The advantages of XRF include real-time results, when used in scanning mode on surface soil, or near real-time results when deeper samples are collected and analysed in the field. The usefulness for specific site-characterisation purposes can be evaluated by comparison of results from split samples analysed by field XRF with laboratory results over a range of analyte concentrations.

    7.4.5          Field gas chromatography
Field gas chromatography (GC) may be used for the analysis of volatile and semi-volatile compounds in soil, soil vapour and water. The two main components of a GC are a column to separate the individual constituents and a detector (such as a PID or FID) to measure the signal response of the constituents. The analysis is compound-specific and potentially has the greatest accuracy of all the commonly used field analytical techniques.

    7.4.6          Immunoassay test kits
Immunoassay test kits, using antibody-antigen reactions, can be used to measure petroleum hydrocarbons in soil and water. For most kits, the intensity of the colour development is inversely proportional to the amount of substance present. The concentration is determined by comparison with a reference standard or with a portable photometer.

7.5              Stockpile sampling
An in situ soil sampling program informed by site history, inspection and contaminant form is the preferred approach for site assessment. On occasions it is necessary to stockpile soils that have not been assessed or only partially assessed in situ, and to devise