Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:6:p7
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 6 (pt 7/10)
Character Range: 198934–202534

as 'not limiting' or 'NL'.
  (5)     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.

  (6)     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.

  (7)     To obtain F1 subtract the sum of BTEX concentrations from the C6-C10 fraction.

  (8)     To obtain F2 subtract naphthalene from the >C10-C16 fraction.

Table  1A(5) Soil vapour HSLs for vapour intrusion (mg/m3)
              HSL A & HSL B                   HSL C                      HSL D
              Low – high density residential  recreational / open space  Commercial / Industrial
CHEMICAL      0 m to <1 m                     1 m to <2 m                2 m to <4 m              4 m to <8 m  8 m+        0 m to <1 m  1 m to <2 m  2 m to <4 m  4 m to <8 m  8 m+       0 m to <1 m  1 m to <2 m  2 m to <4 m  4 m to <8 m  8 m+
SAND
Toluene       1300                            3800                       7300                     15 000       29 000      NL           NL           NL           NL           NL         4800         16 000       39 000       84 000       NL
Ethylbenzene  330                             1100                       2200                     4300         8700        NL           NL           NL           NL           NL         1300         4600         11 000       25 000       53 000
Xylenes       220                             750                        1500                     3000         6100        NL           NL           NL           NL           NL         840          3,200        8000         18 000       37 000
Naphthalene   0.8                             3                          6                        10           25          410          NL           NL           NL           NL         3            15           35           75           150
Benzene       1                               3                          6                        10           20          360          2400         4700         9500         19 000     4            10           30           65           130
F1(8)         180                             640                        1,300                    2600         5300        86 000       NL           NL           NL           NL         680          2800         7000         15 000       32 000
F2(9)         130                             560                        1200                     2400         4800        NL           NL           NL           NL           NL         500          2400         NL           NL           NL
SILT
Toluene       1400                            14 000                     32 000                   69