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 well 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 requirements of the beneficiaries, 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 investigative site work. It should result in the development of a conceptual understanding of the subsurface and inform on the best course of action for later field work. It will also provide valuable information to support the drafting of the drilling/construction 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 (geophysics, pilot boreholes) may or may not be required and will often be carried out in tandem with the drilling works.
Hydrogeologists should be engaged throughout the construction process. They should support the drafting 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:
Collecting information about the subsurface
Drilling provides a unique opportunity to obtain information about the aquifer that you are looking to exploit. The information collected during the drilling phase will inform on all future aspects associated with the well. The data will be used to design the well installation and will also help with pumping test interpretation. A properly logged borehole provides a valuable source of data that can be used long after the lifetime of the well itself.
Overseeing the Drilling Contractor
The drilling supervisor also ensures that the drilling contractor carries out the work as defined by the technical specifications. The supervisor records conversations, periods of standby, well consumables used and any problems encountered, in order to ensure that the drillers invoice matches the work undertaken.
Post construction, before investing in pumps, pipes and associated infrastructure, certain key information is required about the well:
- Will the well be able to supply water of adequate quality and quantity over the lifetime of the associated infrastructure?
- Will the abstraction impact on nearby water features or water users
- What well infrastructure should be installed to produce the most cost effective water supply (ie pump type, pumping rate.
To obtain answers to these questions a pumping test needs to be carried out. The type of pumping test undertaken will depend on the risks associated with the well. In general the more water required from a water point, the more complex the pumping test that is carried out.