Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p30
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 30/117)
Character Range: 430186–433540

there is a potential for contaminants to be present in an aquifer it is important to understand and predict where they are most likely to be concentrated prior to selecting the appropriate groundwater investigation method. Without this consideration, there is the potential for errors, some of which may result in:
    * cross-contamination within and/or between aquifers
    * non-detection of groundwater contamination
    * inaccurate or misleading data
    * expenditure of excessive resources where more simple and cost-effective methods could have been used.

8.2              Monitoring well establishment

    8.2.1          Introduction
In general, most groundwater investigations in Australia are conducted using information obtained from cased, semi-permanent or temporary groundwater monitoring wells. Monitoring wells are used for a range of applications including:
    * groundwater sampling for ex situ analysis
    * monitoring and/or profiling in situ groundwater parameters
    * monitoring of groundwater level fluctuations
    * aquifer testing.
Wells retained as part of a monitoring network should be properly maintained to ensure the integrity of the sample data collected. Well lifespan will depend on the materials used, the standard of installation and whether aggressive ground conditions are present. The monitoring plan should include provisions to inspect and assess monitoring wells for their suitability for monitoring purposes. Damaged or abandoned bores may provide conduits for future contamination unless properly decommissioned. Monitoring wells which are no longer required or are unsuitable for continued monitoring should be decommissioned in accordance with jurisdictional requirements.

The following overview of drilling methods is largely based on information in EPA Victoria (2000) and SA EPA (2007), EA (2006) and Standard practice for design and installation of groundwater monitoring wells, ASTM D5092 (2004). Additional information can be found in Aller et al. (1989), Driscoll (1986) and the Manual of methods, applications and management produced by the Australian Drilling Industry Training Committee (ADITC 1997).

    8.2.2          Logging of boreholes
A careful record of the geology encountered during drilling should be described and classified in accordance with Geotechnical site investigations, AS 1726-1993. Example logs are included in Appendix D.

Field check lists are available in the Toolbox at www.scew.gov.au/nepms/assessment-of-site-contamination.html to aid documentation of essential information including the soil profile and well construction.

Monitoring wells may also be logged using various geophysical techniques, for example, to determine aquifer characteristics in more detail and to supplement other methods (for example, geological logging, core analysis, aquifer tests, water sampling and analysis). Further information can be found in ASTM D5753-05 Guide for planning and conducting borehole geophysical logging (and related standards) and at the United States Geological Survey website: http://ny.water.usgs.gov/projects/bgag/intro.text.html.

    8.2.3          Well construction
Monitoring wells should be constructed to an appropriate standard and from suitable materials to ensure that high quality samples can be collected over the projected lifetime of the well.