Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p38
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 38/117)
Character Range: 453078–456188

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 ensure that groundwater samples have minimum exposure to the atmosphere. Micro-filtration syringes are now widely available and present a viable option to filter in the field even for silty aquifers.
Filtered samples should be collected in pre-prepared bottles containing sufficient acid to maintain the pH of the sample to < pH 2.

Filtration to remove sediment from groundwaters upon receipt in the laboratory is not recommended for analysis of dissolved metals unless it has been demonstrated that the analystical results are consistent regardless of whether filtering is carried out in the field or the laboratory.

Field filtration is not required for total metal analysis.

Sample filtration devices should be decontaminated between uses or discarded to prevent cross-contamination and to ensure continued effectiveness. Further information may be found in SA EPA (2007) and EPA Victoria (2000).

    8.2.5          Monitoring and profiling of groundwater parameters
Some physicochemical parameters cannot be reliably measured in the laboratory as their characteristics change over a very short timescale. Parameters that should be measured in the field include pH, electrical conductivity (EC), temperature, dissolved oxygen (DO) and redox potential (Eh). If ferrous iron is one of the selected analytes, it also is best analysed in the field.

It is recommended that field parameters are measured in a flow-through cell to avoid contact between the groundwater and the atmosphere. A flow-through cell can also enable continuous measurement and monitoring of key parameters during purging to identify when a representative sample may be obtained.

There is a wide range of equipment available for the measurement and logging of these parameters. It is important that quality assurance protocols are developed and implemented. The procedures should include the use of suitable calibration standards, where the calibration spans the anticipated range of results, and accuracy checks. Where measurements are made over a number of hours, periodic readings of appropriate reference solutions should be incorporated to ensure that the calibration is stable. Calibration procedures vary between meters and between manufacturers so it is important to follow the manufacturer's instructions for correct and accurate operation of each piece of equipment. Further information can be found in SA EPA (2007) and Sundaram et al. (2009).

    8.2.6          Groundwater levels and flow direction
Groundwater level measurements are essential to determine groundwater and contaminant flow directions within aquifers and interaction with surface water bodies. These measurements can provide information on lateral and vertical head distribution and hydraulic gradients within individual aquifers and between aquifers in layered aquifer systems (EPA