Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p36
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 36/117)
Character Range: 447361–450463

by laboratories is Standard methods for the examination of water and wastewater (APHA et al. 2005).

Overviews of groundwater sampling procedures are readily available; for example, SA EPA (2007) includes information about:
    * development of monitoring plans
    * pumping and sampling equipment
    * sampling methods
  -       groundwater level measurement
  -       purging
  -       sample collection methods
  -       filtration
  -       NAPL sampling
  -       decontamination
    * sample identification, transport and storage
  -       labelling and identification
  -       preservation techniques
  -       QA/QC.

Detailed information can be found in Standard AS/NZS 5667.11-1998; MDBC (1997); EPA Victoria (2000); Nielsen (2006) and Nielsen & Nielsen (2005).

An appropriate method of groundwater sampling should be selected in relation to the nature of the target analytes and the hydraulic characteristics of the monitoring well. In general, the use of low-flow submersible pumps or positive-displacement pumps capable of controlling flow rates and minimising purging requirements are the preferred methods of groundwater sampling for site characterisation purposes. A discussion of the benefits and limitations of low-flow purging and sampling can be found in ASTM D6771-02.

No-purge sampling techniques (see below) may also be appropriate, particularly for long-term monitoring applications. A discussion of the applications and the benefits and limitations of passive sampling can be found in ITRC (2005).

Purging and sampling methods using bailers or high speed pumps are not recommended due to the difficulty of obtaining a representative groundwater sample. These methods result in degassing of samples and can also introduce high levels of turbidity. Sampling-induced turbidity may be mitigated by using low-flow purging and sampling techniques (Puls & Barcelona 1996).

Generally, the same methods should be used each time the wells are purged and sampled to avoid introducing sampling method-related uncertainties to the analytical data (SA EPA 2007). Where an improved technique becomes available, it is recommended that it is trialled in combination with the existing sampling method to establish the nature and magnitude of any changes in analytical results as a result of the new sampling method.

Passive sampling devices (for example, passive diffusion bags for VOCs) do not require pumping or purging of groundwater to acquire a sample. These sampling devices are placed at a selected depth in the well and rely on ambient flow through the well screen for sampling.

Three types of passive sampling technologies are available:
    * devices that recover a grab sample of groundwater (producing an equilibrated 'snapshot' of groundwater quality)
    * devices that rely on diffusion of the analytes for the sample to 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