Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p26
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 26/117)
Character Range: 418230–421392

8

The recommended sampling frequency (Table 4) applies to the characterisation of homogenous soils suspected of contamination. Lower sampling rates may be derived for soil quantities greater than 200 m3 by applying statistical analysis. Worked examples of applying 95% UCLave to characterise stockpiles are included in EPA Victoria (2010).

Jurisdictions may have specific requirements where materials are to be recycled, recovered and reused for beneficial purposes.

    7.5.3          Sample point distribution
The stockpile should be sectioned into an appropriate distribution of sampling locations based on inspection, site history and other assessment data about the nature of contaminants present. If a section of the stockpile is known to have a higher level of heterogeneity and greater contamination risk and the balance of the stockpile is relatively homogenous with low-level contamination, sampling bias to the more contaminated section may be considered. If this information is not known, a uniform sample point distribution should be used. A plan should be developed of the stockpile sections and the corresponding sample locations that represent each section. This will allow physical separation of portions of the stockpile for further characterisation, if required, after receipt of the analytical results.

    7.5.4          Sampling
Collection of samples from the exterior 300 mm of the stockpile should be avoided due to the higher risk of weathering and grain size grading errors.

Samples for inorganic and non-volatile components should be taken at various depths towards the centre of the stockpile from 300 mm below the stockpile surface. Compositing may improve the reliability of samples for inorganic analysis. Composites should be based on equal quantities of material from 4 random locations and depths in the area of the stockpile allocated to the sample. The trowel should be cleaned after soil collection at each random location and the collected material thoroughly mixed on a clean surface, subsampled and preserved for chemical analysis.

Composites are not suitable for the assessment of pH, volatile substances and semi-volatile substances such as petroleum hydrocarbons, OC/OP pesticides and lower molecular weight PAHs. Samples for volatile and semi-volatile compounds should be taken without delay from a freshly excavated surface 500 mm or greater depth below the stockpile surface.

Systematic sampling directly from excavator buckets during the excavation and stockpile formation process or for appraisal of larger stockpiles using appropriate QA/QC processes is an acceptable strategy in site assessment. Further guidance on stockpile sampling may be obtained from EPA Victoria's Industrial waste resource guidelines (2010).

7.6              Assessment of soil leachability to groundwaters and surface waters

    7.6.1          Leaching potential to groundwater and surface water
Contaminants in soil can leach to groundwater under certain conditions. For inorganic substances, leachability is particularly affected by soil pH, contaminant solubility and redox (Eh) conditions.

The leachability characteristics