Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p4
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 4/9)
Character Range: 928702–931825

property that can be measured, and which often has a significant effect on the risk assessment outcome for volatile and persistent contaminants. Samples of uncontaminated soil should be tested for Foc such that the concentration of carbon measured is not influenced by the potential presence of organic contaminants. The number of samples required depends upon the inherent variability of the soil being characterised. Sufficient (based on site-specific factors) samples should be taken to represent each soil type being characterised.

    3.3.2          Other key pathway parameters
Other key physical and chemical parameters that may be required for the risk assessment process include the following:
    * site topography and drainage direction
    * depth to groundwater
    * groundwater flow direction and velocity
    * groundwater geochemical parameters including pH, redox potential, dissolved oxygen and major element chemistry
    * presence of oxygen in the vadose zone
    * soil type classification
    * presence of physical barriers or conduits (that may act as preferential pathways)
    * moisture content
    * depth of contamination.
Data collection for the establishment of these variables is part of the site investigation process. Guidance on site investigation is provided in Schedule B2.

3.4              Data evaluation
The data evaluation stage is the first stage of the development of the CSM. The level of effort expended and detail of reporting necessary should be proportionate to the amount of data available.
The data evaluation steps include:
    * assessing data quality
    * rejecting unreliable data or those that fail to meet data quality objectives (DQOs)
    * defining the source in three dimensions
    * refining the understanding of pathways
    * undertaking Tier 1 screening of chemical data against HILs or relevant criteria for those chemicals without HILs (checked with auditor/regulatory authority)
    * identifying contaminants of concern.

    3.4.1          Data quality assessment and data quality objectives
Guidance on data quality assessment is presented in Schedule B2 and enHealth guidance (enHealth 2012a) and should be followed when collecting data for risk assessment. Data quality and precision should be such that uncertainty in the risk assessment can be determined and minimised; data quality uncertainties should be explicitly discussed in the uncertainty analysis. Where a number of studies are being combined to provide definition of the source term, particular attention should be paid to the following:

     3.4.1.1         Analytical methods
Use of different analytical and sample preparation methods can cause significant differences in results. For example, use of a 'clean-up' step (silica gel) in petroleum hydrocarbon analysis removes polar hydrocarbons such as soil humic acids, resulting in a much lower result in many cases. Further information is provided in Section 2.4.4 of Schedule B1. Guidance on analytical methods and their selection is given in Schedule B3.

     3.4.1.2         Data quality objectives
Data collection is a vital