Territory Stories

Summary of past drilling activity within the Great Artesian Basin, Great Artesian Basin Coordinating Committee

Details:

Title

Summary of past drilling activity within the Great Artesian Basin, Great Artesian Basin Coordinating Committee

Creator

Great Artesian Basin Coordinating Committee

Collection

E-Publications; E-Books; PublicationNT; D0851

Date

2017-11

Location

Great Artesian Basin

Description

The Great Artesian Basin Coordinating Committee (GABCC) requested bore hole data from the state and territory government databases to be collated to estimate the number of bore holes that have been drilled into the Great Artesian Basin (GAB). This is to inform discussions on the legacy of the 140 years of past drilling activity with respect to the long term management of the groundwater resources of the GAB.

Notes

Made available via the Publications (Legal Deposit) Act 2004 (NT).

Table of contents

Executive summary -- Introduction -- Scope -- Limitations of the data -- Summary of all available data -- Total number of reported bore holes drilled -- Date of construction -- Water bore data -- Drilling in areas of artesian conditions -- Water supply bore depths -- Estimated replacement value of water supply bores -- Number of bores with uncontrolled artesian flow -- Discussion -- Appendix A-E

Language

English

Subject

Great Artesian Basin; Drilling Activity

Publisher name

Great Artesian Basin Coordinating Committee

Place of publication

Australia

Series

D0851

Format

27 pages : colour illustrations, colour maps, tables ; 30 cm.

File type

application/pdf.

Use

Copyright

Copyright owner

Great Artesian Basin Coordinating Committee.

License

https://www.legislation.gov.au/Details/C2019C00042

Related links

http://www.gabcc.gov.au/

Parent handle

https://hdl.handle.net/10070/299513

Citation address

https://hdl.handle.net/10070/383677

Page content

13 As a broad category, bores less than 200m may be considered to be of lesser consequence if failure occurs when compared to the deeper bores. However it should be recognised that within this depth category there would be areas of the GAB that both artesian and sub artesian conditions exist. Future data extractions could consider a more targeted approach in identifying the higher risk water bores in terms of their construction within this zone. Whilst the total estimated replacement costs of those water supply bores in the GAB that depth data is available is $4,351 million, excluding the shallower bores (a total number of 23,507 bores), the estimated replacement value of the 9,276 water supply bores that are greater than 200m is $3,258 million. Pressure cementing of water supply bore holes was not widely adopted until the 1950s1960s when jurisdictions required artesian flows of new bores to be controlled and capped. Of the 38,174 water bores drilled, at least 6,629 were drilled to depths expected to have artesian, or previously artesian, conditions and therefore requiring pressure cementing. Of these, 57 percent (2,748) were drilled prior to 1960. From the data available for this review the proportion of these bores that have been decommissioned or reconditioned to current standards to prevent inter-aquifer leakage and to manage artesian flows via appropriate headworks could not be ascertained. The government databases could be interrogated specifically to do this in the future although there is limited information on the current condition status of private bores in NSW. The 535 bores with uncontrolled flow represent a high risk group with regard to resource management. Of these 463 were constructed prior to 1960. For many of these the actual flows to surface are very small however given their age and likely casing integrity there is expected to be many that have flow loss through breached casing below ground surface. States have been progressing the repair or capping of these bores (refer Appendix E). There may also be a proportion of currently sub artesian bores which will become artesian as basin pressure increases due to the previous water saving programs. The increase in basin pressures can also result in an increase in the rate of inter aquifer leakage via breached casing. It is recommended that future reviews of drilling activities in the GAB consider water supply bores separately from coal, oil and gas exploration and production drilling. The drilling and reporting standards are vastly different and it would be more informative to analyse these separately and then combine the findings to identify high risk groups of bores or drilling activities.