Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 9/21)
Character Range: 63086–66089

non-petroleum compounds are present.

The potential for inclusion of non-petroleum compounds in the results may be relevant for site-specific assessment of petroleum hydrocarbon contamination. For example, the TRH analytical results may be overly conservative if soil organic matter is unusually high, for example from heavy applications of mulch, manure, compost or other natural organic material, or the presence of other synthetic organic compounds which are extractable in the analytical process. To assess potential false positive results, it is recommended that equivalent soil from the site, unaffected by petroleum hydrocarbon contamination, is analysed for comparison.

Where there is reasonable doubt as to the nature of the contamination, the sample may be subjected to a silica gel clean-up and analysed by gas chromatography mass spectrometry (GC-MS) (or other appropriate analytical method) to assist with the identification of contamination of petroleum origin. In these cases, an analyst report should be obtained with an interpretation of the chromatogram and the nature and extent of contamination present in the sample.

    2.4.6          Petroleum hydrocarbon compounds and fractions
HSLs have been developed for BTEX and naphthalene plus four carbon chain fractions based on the fractions adopted in the Canada-wide standard for petroleum hydrocarbons (PHC) in soil (CCME 2008). The fractions are listed in Table 1 below:
Table 1. HSL fractions and corresponding equivalent carbon range
Fraction number  Equivalent carbon number range
F1               C6 – C10
F2               >C10 – C16
F3               >C16 – C34
F4               >C34  - C40

The HSLs are provided in Tables 1A(3) – 1A(5)).

BTEX results should be subtracted from the TRH C6 – C10 analytical results for comparison with the HSL for F1. Likewise, naphthalene should be subtracted from >C10 – C16 for comparison with the HSL for F2.

Chemicals in the >C16-C34 and >C34-C40 fractions are non-volatile and therefore not of concern for vapour intrusion, however, exposure can be via direct contact pathways (dermal contact and incidental ingestion and inhalation of soil particles). Direct contact HSLs for these fractions can be found in Friebel and Nadebaum (2011a).

    2.4.7          Soil texture
HSLs for soil, groundwater and soil vapour have been developed for sand, silt and clay soils based on the US soil texture classification system (Friebel & Nadebaum 2011a). The HSLs assume a uniform soil profile and the soil texture making up the greatest proportion of the soil profile should be used in selecting the appropriate HSLs (Friebel & Nadebaum 2011a and 2011b).

For Tier 1 soil assessment, the HSL classifications of sand, silt and clay may be broadly applied to the soil texture classification in Table A1 of Standard AS 1726.
Table 2. HSL soil classification and equivalent soil classification in AS 1726
HSL soil classification  AS 1726 Equivalent
Sand                     Coarse-grained soil
Silt