Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:8:p1
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 8 (pt 1/2)
Character Range: 1730211–1732930

8                5.06
8.5              9.17
9.0              17.45

The above ALF values were calculated after a maximum of 1.5 years ageing in the field, therefore in most 'aged' Australian sites the ALFs would be larger. However, there is no information available that would permit estimates of how much larger the ALFs would be and therefore the above ALF values were used to calculate the Ni SQGs.

9.7.2         Use of ageing and leaching factors in the methodology
There are two possible approaches to incorporating the relationship between ALF and soil pH into the methodology for deriving SQGs. In the first, a soil pH that is reasonably representative or protective of the majority of Australian soils is selected and the corresponding ALF is then used to calculate the aged SQGs. The resulting SQGs would be protective of all aged soils with a pH higher than the selected pH, but would not provide the same level of protection to soils with lower soil pH. Such soils would have to proceed to further desktop analysis by using the ALFpH relationship to determine the appropriate ALF for that soil and then apply that to the fresh contamination SQGs. To maximise the utility of this approach and minimise the number of sites that would require the additional analysis, the selected soil pH would have to be low, perhaps as low as 5. This would result in an ALF of 1.07 and with such a small increase in the resulting aged SQGs, it is doubtful that it would be of any real benefit.

The second approach would be to fully adopt the ALFpH relationship into the methodology for deriving SQGs, where the pH of the site would need to be determined and then the appropriate ALF calculated for the site and applied to the toxicity data to generate the aged contamination ACLs and thence the aged SQGs. While the latter is more complex, the benefits of having the most scientifically defensible ACLs and SQGs outweigh this. It is recommended that SQGs are derived by multiplying fresh (non-aged and non-leached) toxicity data by the ALF determined using the ALFpH relationship (see equation 11).

9.7.3         Calculation of soil quality guidelines for aged nickel contamination based NOEC and 10% effect concentration toxicity data

9.7.3.1         Calculation of soil-specific added contaminant limits
The aged SQG(NOEC & EC10) values for Ni were calculated using the same methodology as that used for the SQG(NOEC & EC10) values for fresh Ni contamination, with two exceptions. These were (i) that the 'fresh' toxicity data was corrected using the Ni ALFs (equation 11) and (ii) the ABCs were the 25th percentile values for old suburbs from Olszowy et al. (1995). The resulting ACL(NOEC & EC10) values for aged Ni