Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p37
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 37/117)
Character Range: 450213–453350

reach and maintain equilibrium with the sampled medium
    * devices that rely on diffusion and sorption to accumulate analytes in the sampler.
Some of these passive sampling devices are applicable to the sampling of surface waters and vapour as well as groundwater. Further information can be found in ITRC (2005) and ITRC (2007a).

The selection of the appropriate equipment for a groundwater investigation should be based on careful consideration of the attributes of the target analytes, the likely contaminant distribution, cost and logistical issues, field filtration requirements, and decontamination requirements.

8.2.4.1         Target analytes
Certain analytes are prone to effects of aeration and agitation and sampling equipment should be selected to cause minimal agitation and chemical alteration of the sample, for example, low-flow techniques are recommended for quantitative assessment of VOCs and SVOCs; bailers are not appropriate.

Information on monitoring and sampling LNAPLs using oil-water interface probes, oil indicator pastes and special bailers can be found in Clements et al. (2009).

Sampling equipment should also have negligible capacity for sorption, precipitation and oxidation of analytes of interest.

8.2.4.2         Contaminant distribution
Due to a range of chemical and/or physical characteristics, contaminants may be concentrated in certain parts of the aquifer under investigation. The sampling equipment should be capable of targeting the depth interval most likely to contain the target analytes. For example, special bailers are available for the sampling of NAPLs, while bottom-loading bailers are available for investigating DNAPLs.

8.2.4.3         Decontamination requirements
All equipment used in the sampling procedure which either enters the well bore or holds the groundwater sample should be decontaminated before and after each sample is collected. Samples of the rinsate should be included in the QA/QC program. Depending on the potential for cross-contamination between wells or within the profile of a single well, certain equipment may be relatively difficult to decontaminate and it may be necessary to opt for more simple sampling systems or to dedicate sampling equipment to a particular well or interval.

In addition to the above decontamination procedures, it is good practice to sample wells with no/minimal contamination first to minimise potential cross-contamination of samples.

8.2.4.4         Field filtration
In surface water bodies, a substantial amount of metals can be transported adsorbed to suspended particles and filtering needs to be undertaken to identify the dissolved component if quantification of dissolved metals is required.

This is much less the case in groundwater systems where particles cannot easily pass through the porous aquifer matrix. Typically filtration with a 0.45 μm filter will remove the majority of suspended particulates, however, it may be necessary to filter samples with a 0.1 μm filter to remove all suspended particulates.

For dissolved metals, in-line disposable filters (or micro-filtration syringes) are recommended to