Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:1850:p35
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 1850 (pt 35/117)
Character Range: 444580–447640

development
All bores intended for monitoring water quality should be developed after drilling to remove fine sand, silt, clay and any drilling mud residues from around the well screen to ensure the hydraulic functioning of the well. Development should be carried out as soon as possible after drilling and installation, however, a minimum of 24 hours should be allowed for bentonite seals to fully hydrate and grout to cure (harden and set). A detailed record should be kept of well development activities and reported in the relevant site assessment report.

Development usually involves agitating the water column in the well bore and pumping the water out until it runs clear. During development, bore yield should be estimated by monitoring the rate of recovery of water in the bore after pumping. This information can then be used to select suitable methods for subsequent purging and sampling (SA EPA 2007).

Development should continue until a defined endpoint has been reached (EA, 2006), such as:
    * chemical indicator stability– using field measuring techniques for pH, EC and dissolved oxygen, development is continued until these parameters stabilise in abstracted water, or
    * reduced turbidity – development is continued until the abstracted water is reasonably clear and free of suspended solids.
After development, bores should be left for a period until borewater chemistry can be demonstrated to have stabilised (generally between 24 hours and seven days) before samples are collected. Longer periods are applicable to low permeability aquifers and to reduced groundwater conditions where it may take days to weeks to fully equilibrate, depending on the aquifer properties.

Care should be taken to dispose of any contaminated water responsibly and not to allow it to enter the stormwater drainage network or to impact uncontaminated soils at the site.

    8.2.4          Groundwater sampling
It is essential that groundwater sampling methods result in the collection of samples that are representative of aquifer conditions. Management decisions that may involve considerable expenditure and potential inconvenience to the public will be based on these results. In many circumstances, budgeting for additional sampling and analysis costs for site characterisation for definition of groundwater contamination problems could save further assessment expenditure and costly delays to property transactions and site development.

Where possible, established 'standard methods' from recognised sources such as Standards Australia, the United States Environmental Protection Agency (US EPA), the American Public Health Association (APHA) and International Standards Organisation (ISO) should be used for the analysis of groundwaters. The general reference used 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