Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p9
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 9/10)
Character Range: 206504–209979

based on vapour pressures of the pure chemicals. Where soil vapour HSLs exceed these values a soil-specific source concentration for a petroleum mixture could not exceed a level that would result in the maximum allowable vapour risk for the given scenario. For these scenarios, no HSL is presented for these chemicals and the HSL is shown as 'not limiting' or 'NL'.
   5. Soil vapour HSLs should be compared with measurements taken as laterally close as possible to the soil or groundwater sources of vapour (i.e. within or above vapour sources). Consideration is required of where the sample is taken, the current condition of the site and the likely future condition of the site. Shallow gas measurements in open space (less than 1 m below ground surface) may be subject to influences of weather conditions and moisture.
   6. The figures in the above table may be multiplied by a factor to account for biodegradation of vapour. A factor of 10 may apply for source depths from 2 m to <4 m or a factor of 100 for source depths of 4 m and deeper. To apply the attenuation factor for vapour degradation, a number of conditions must be satisfied. Firstly, the maximum length of the shorter side of the concrete slab and surrounding pavement cannot exceed 15 m, as this would prevent oxygen penetrating to the centre of the slab. Secondly, measurement of oxygen in the subsurface is required to determine the potential for biodegradation. Oxygen must be confirmed to be present at >5% to use these factors.

   7. For soil texture classification undertaken in accord with AS 1726, the classifications of sand, silt and clay may be applied as coarse, fine with liquid limit <50% and fine with liquid limit >50% respectively as the underlying properties to develop the HSLs may reasonably be selected to be similar. Where there is uncertainty, either a conservative approach may be adopted or laboratory analysis should be carried out.

   8. To obtain F1 subtract the sum of BTEX concentrations from the C6-C10 fraction.

   9. To obtain F2 subtract naphthalene from the >C10-C16 fraction.

Table 1B(1) Soil-specific added contaminant limits for aged zinc in soil
Zn added contaminant limits (ACL, mg added contaminant/kg)
Areas of  ecological significance
pHa                                                         CECb (cmolc/kg)
                                                            5                10   20    30    40    60
4.0                                                         15               20   20    20    20    20
4.5                                                         20               25   25    25    25    25
5.0                                                         30               40   40    40    40    40
5.5                                                         40               60   60    60    60    60
6.0                                                         50               90   90    90    90    90
6.5                                                         50               90   130   130   130   130
7.0                                                         50               90   150   190   190   190
7.5                                                         50               90   150   210   260   280
Urban residential/public open space1
pHa                                                         CECb (cmolc/kg)
                                                            5                10   20    30    40    60