Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:2:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 2 (pt 2/4)
Character Range: 1504826–1507599

accounted for. One factor that was incorporated into the methodology was the background concentration. In order to do this, the data used to derive the SQGs was expressed in terms of the amount of contaminant that had to be added to the soil to cause toxicity. When this toxicity data was used in accordance with the methodology, the resulting value was termed the added contaminant level (ACL). An ambient background concentration (ABC) specific to the soil being investigated was then added to the ACL to calculate the SQG.

ACL values are generated as part of the methodology of deriving SQGs. Thus, it is necessary to differentiate the ACLs generated in deriving SQG(NOEC & EC10) from those generated in deriving SQG(LOEC & EC30) and SQG (EC50) values. The ACL generated in deriving an SQG(NOEC & EC10) is termed the NOEC and EC10-based ACL (ACL(NOEC & EC10)). Similarly, ACLs generated in deriving SQG(LOEC & EC30) and SQG (EC50) values are referred to as the LOEC and EC30-based ACL (ACL(LOEC & EC30)) and the EC50-based ACL (ACL(EC50)).

Figure 1. Overview of the  methodology for deriving soil quality guidelines based on NOEC and EC10 data (SQG(NOEC & EC10)) indicated by the green (far left) arrows, based on LOEC and EC30 data (SQG(LOEC & EC30)) indicated by the orange (middle) arrows and based on EC50 data (SQG(EC50)) indicated by the red (far right) arrows. As part of this process, ACLs and ABCs are calculated. The differences between the three SQGs are presented in Table 1.
The key steps in the methodology are:
   1. determining the purpose of the SQG and the appropriate level of protection
   2. determining the most important exposure pathways
   3. collating and screening the toxicity data
   4. determining whether the contamination is fresh or aged and whether there are ageing/leaching factors available to account for this
   5. normalising the toxicity data
   6. calculating the ACL
   7. accounting for biomagnification
   8. measuring or calculating the ABC
   9. calculating SQG(NOEC & EC10),  SQG(LOEC & EC30) and SQG(EC50) values for fresh contamination in soils with different land uses
  10. calculating SQG(NOEC & EC10),  SQG(LOEC & EC30) and SQG(EC50) values for aged contamination in soils with different land uses.
These key steps and the decision pathway involved in deriving ACL(NOEC & EC10) and SQG(NOEC & EC10) values are provided in Figure 2 below. Exactly the same procedure would be used to derive SQG(LOEC & EC30) and SQG(EC50) values, except that different toxicity data would be used (Table 1). Details of the methodology for calculating SQGs are provided in Schedule B5b.

Land has a variety of potential uses, and the level of protection that is appropriate for each land use varies. For example, it is appropriate for