Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:3:p2
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 3 (pt 2/5)
Character Range: 2027188–2030570

health (groundwater-dependent ecosystems). Depending on the site setting, this may include surface water bodies such as wetlands, streams and rivers reliant on groundwater base flow, some estuarine and near-shore marine systems, as well as aquifer and cave ecosystems. Consideration of the water body/groundwater characteristics will determine whether the freshwater or marine water GILs are the most appropriate to apply.
Table 1. Summary of relevant guidelines to protect environmental values of groundwater.
Environmental value                                     Relevant guideline
Ecosystems                                              AWQG (fresh and marine ecosystem guidelines)
Drinking water                                          ADWG
Recreational use*                                       GMRRW
Industrial use
    * Agricultural use (irrigation and stock watering)      * AWQG (irrigation and stock watering guidelines)
    * Aquaculture                                           * AWQG (aquaculture)

* The recreational and aesthetics sections of the AWQG have been superseded by the GMRRW (NHMRC 2008).

3.3              Background groundwater quality
The application of the policy framework includes consideration of background groundwater quality. Background groundwater quality is considered to be the sum of both ambient and natural sources in the local area of a site. Very few organic chemicals would be expected to have elevated natural background levels in groundwater. However, in the case of metals, metalloids and some inorganic substances, background concentrations may be elevated due to both natural and ambient background contributions.

The assessment of background water quality should be undertaken at an area(s) that is not affected by the activities that have contributed to the contamination present at the site. For example, it may be appropriate to collect samples unaffected by the contamination upgradient of the impacted area; otherwise a suitable area in the vicinity of the site, which is unlikely to have been impacted by the potential contaminants of concern, should be selected. Further information may be found in SA EPA (2008).

In addition to the potential contaminants of concern identified in the conceptual site model, it is recommended that the sampling and analysis plan should include the analysis of major ions to assist with differentiation between contaminated and non-contaminated groundwater.

Sufficient sampling in terms of both areal and temporal considerations should be undertaken to establish the natural variation in groundwater quality due to seasonal effects. Where sufficient concentration data is available for statistical analysis, the 80th percentile of the background concentration data may be used for comparison with the site data (ANZECC & ARMCANZ 2000).

3.4              Fundamentals of the tiered approach

    3.4.1         Tier 1
A Tier 1 assessment is the first stage of assessment and provides an initial screening of the site data. This includes:
    * reviewing site contamination history, identifying all past and present contaminating activities and associated potential contamination
    * reviewing available information about local and regional geology and hydrogeology
    * identifying aquifers and confining layers, groundwater flow domain, potential receptors
    * identifying natural