Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p10
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 10/21)
Character Range: 65817–68822

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                     Fine-grained soil - silts and clays (liquid limit <50%)
Clay                     Fine-grained soil - silts and clays (liquid limit >50%)

Where there is reasonable doubt as to the appropriate soil texture to select, either a conservative selection should be made (i.e. select coarsest applicable grain size such as sand) or laboratory analysis carried out to determine particle size and hence soil texture sub-class (refer Section 7.3.1 in Friebel and Nadebaum 2011b). If particle size analysis is undertaken then laboratory measurement of additional parameters used in site-specific risk assessment (such as soil moisture content, organic carbon content and saturation porosity - refer Friebel & Nadebaum 2011b for further information) could also be considered if further assessment is possible. If laboratory measurement is undertaken, sufficient samples should be obtained and analysed to determine a representative value for each soil unit of interest for the assessment.

    2.4.8          Land use
The HSLs are derived for various depths to source and for the same generic land uses as for the HILs (described in detail in Schedule B7). The values for residential A and B are combined in the HSL tables as they are based on the same exposure conditions for the vapour inhalation pathway (i.e. the same amount of time spent indoors).

The HSLs are applicable to ground floor land use. If the vapour exposure is acceptable at ground level, it can be assumed that it is also acceptable for floors above ground level.  For multistorey buildings where non-residential uses (e.g. car parking or commercial use) exist in a basement or at ground level, then land use category D (commercial/industrial) should be applied.

Any sensitive land uses e.g. childcare or day care centre will require application of HSL A irrespective of their planning zoning.  Secondary school buildings (as opposed to secondary school grounds) should also be assessed using HSL A.

    2.4.9          Adjusting  HSLs to site-specific circumstances
The HSL methodology enables parameter inputs to be changed to more accurately reflect local soil, site or building conditions. Input parameters should be selected to be representative of long-term stable conditions and appropriate to the soil unit/aquifer of concern e.g. moisture content may vary seasonally and may also be different beneath buildings. Where insufficient data is available to establish a representative value, a conservative approach should be taken, for example, by assuming dry soil moisture conditions in sand. The HSL application and sensitivity documents (Friebel & Nadebaum 2011b, 2011c) provide further details. Jurisdictions may also adopt policies to vary the