To develop a groundwater resource there are a number of phases of work that need to be undertaken including siting, construction and testing. Groundwater Relief supports charities at each of these stages, working when possible with local contractors and groundwater professionals.
Siting a new borehole is a scientific investigative process that needs to balance the availability of groundwater within the underlying geological environment with the accessibility of the site, the water supply requirements, the risks associated with the source and the future impacts of an abstraction on the nearby environment.
There are at least two steps that should be undertaken when siting a borehole:
This should be undertaken prior to any borehole drilling. The desk study will develop a conceptual understanding and establish an indication of the water supply potential. A good desk study will enable design of a site work programme, identify the need for a geophysical survey and where appropriate, the preparation of the borehole drilling specifications and contract.
Field Survey and Intrusive Investigation
A field survey might be carried out to provide further information to improve the desk study conclusions. Intrusive investigation (e.g. pilot boreholes) may or may not be required and will often be carried out in tandem with the drilling works.
Borehole drilling, installation and pump testing
Hydrogeologists should be engaged throughout the borehole drilling and construction process. They should support the preparation of the technical specifications of the contract and supervise the drilling of the borehole.
When supervising the construction phase of the project the groundwater expert performs two key functions:
Hydrogeological data collection
Borehole drilling enables the collection of hydrogeological data to characterise the target aquifer. The data is required to develop an appropriate borehole design and to confirm the hydrogeological conceptual understanding to further characterise the aquifer. A properly logged borehole provides valuable data that should be recorded and registered with the appropriate authorities for future reference.
Overseeing the Drilling Contractor
The supervision of borehole drilling is often overlooked but is a critical aspect of work to ensure accurate technical data is collected, and that borehole installation and development processes are correctly undertaken. Borehole supervision also requires managing the contractor and recording their activities required for cost tracking.
Pump testing is critical and is required to characterise the aquifer response, confirm the sustainable borehole supply potential, assess potential impacts on water features and other water users and to select the pump specification.
The pumping test design (duration, discharge rate etc.) will be dependent on the on the risks associated with the planned supply and quantity of water required.