Introduction: Why Water Bore Drillers Need Minimum Construction Requirements
A high percentage of Australia’s total water use is from groundwater, and this percentage is increasing as surface water resources become more heavily used.
Water bores are the most common means of tapping groundwater. The siting, design, materials, and construction method used all influence the quantity and quality of water obtained.
Drillers play a vital role in the development, use, and protection of the groundwater resource. They provide a service to clients, and thus have a responsibility to ensure that this role is fulfilled through high standards of work and the use of materials appropriate to the particular work involved.
These minimum requirements provide the technical base for licensed drillers, for bore permits, and as a reference for bore construction. This edition separates these requirements into mandatory requirements and recommendations for good industry practice.
Mandatory requirements are enforceable by regulators for the protection of the groundwater resource. All drilling activities shall be conducted in accordance with applicable state and/or territory regulatory requirements.
Good Industry Practice
Good industry practice describes methods and techniques recommended to:
• help satisfy mandatory requirements
• provide efficient and cost-effective water bores
• ensure the long-term efficiency and operation of the water bore.
These requirements are not designed to meet the specific needs of landholders or purchasers, or to replace the specifications that various state and territory water authorities currently use.
In the context of this article, the term ‘drilling operations’ encompasses:
• bore construction
• maintenance and rehabilitation
This article considers the design, materials, reporting, and recording requirements for all aspects of drilling operations. In doing so, these requirements aim to ensure the:
• protection of the groundwater resource from contamination, intermixing, and uncontrolled flow
• long-term economic production of groundwater of the best possible quality.
The finished bore is a result of a number of considerations and decisions. These include:
• the intended purpose of the bore
• geological and hydrogeological conditions, including groundwater quality
• drilling methods
• construction methods
• bore performance improvements (e.g. bore development and disinfection)
• bore performance indicators (e.g. pumping test and water quality test).
The finished bore is further affected by the inherent nature of drilling, which disrupts the native environment. Bores drilled to intersect aquifers will disturb the aquifers by providing a vertical connection between aquifers if not sealed correctly, and a connection can mix different heads or groundwater qualities.
Where drilling intersects groundwater held under pressure, uncontrolled flowing (artesian) bores can result, causing wastage of the groundwater resource and the loss of hydrostatic pressure. All non-flowing bores can potentially provide a means of contaminating groundwater by acting as a conduit for surface run-off.
Deteriorated or abandoned bores that threaten the groundwater resource should be decommissioned in such a way that the hydrogeological environment is maintained or is returned as near as possible to the condition that existed before drilling.