Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p17
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 17/117)
Character Range: 393410–396440

may pose a risk. Deeper sampling to determine the nature and extent of the source of the vapours and the risk they represent may be required—refer Section 9.

The risk to groundwater needs to be assessed according to jurisdictional requirements, especially if receptors may be exposed by current or realistic future use of the groundwater resource—refer Schedule B6.

To delineate contamination laterally, typically samples should be taken until either no further contamination is detected or concentrations are below the relevant investigation levels or site-specific risk-based criteria.

The nature and appearance of drill cores will influence sampling at depth. It is essential that samples are taken from within a natural stratum or fill horizon and not across strata.

At the surface, samples at 0–100 mm or 0–150 mm should be taken unless there is evidence of a thin superficial layer of contamination. Where there is good evidence that contamination is restricted to a thin superficial layer, a shorter sampling interval may be appropriate, however, a subset of deeper samples should be analysed to inform/confirm the CSM. At greater depths, the sampled interval should be no more than 500 mm to avoid a compositing effect.

    7                   Soil assessment

7.1              Introduction
The selection of appropriate site investigation techniques depends on a number of factors including the stage of the investigation (for example, preliminary assessment or detailed delineation, the depth of investigation required, the contaminant type (volatile or non-volatile, bonded or unbonded asbestos-containing-material), the depth and nature of any fill, and whether an undisturbed sample is required.

The most commonly used investigation techniques are test pits, trenching and drilling of shallow boreholes. Samples from shallow depth are generally obtained from test pits and trenches or from augers. Samples from greater depths may be obtained by a range of drilling methods including direct push, hollow stem augers, split spoon, Shelby tube, mud rotary and sonic drilling. Methods capable of providing continuous or near-continuous soil cores, such as direct push, split spoon and sonic drilling, are preferred. Air drilling and solid flight augers provide highly disturbed samples and poor depth control which limits their value for site characterisation purposes. Further information on soil investigation methods can be found in Australian Standards AS 4482.1-2005, AS 4482.2-1999 and AS 1726-1993.

A number of screening tools are also available that can be used to rapidly and cost-effectively identify and delineate VOC and SVOC contamination in both the unsaturated (vadose) and saturated zones. These include soil vapour sampling, and the laser-induced fluorescence (LIF) and membrane interface probe (MIP) tools. LIF and MIP are real-time tools that can provide detailed logs of the sub-surface and can be used in a reactive or adaptive field sampling program, particularly for volatile substances where