Artesian borehole capping exercise in Malawi

In February 2019, Nick Mannix a hydrogeologist from the University of Strathclyde CJF team travelled to Malawi to provide technical input, guidance and training in artesian borehole flow control and capping.

This work is part of a 'Climate Justice Innovation Fund' project, being delivered by BASEflow Malawi [1] and University of Strathclyde. The CJIF project will run over two years and will explore the potential for using artesian groundwater systems to supply sustainable agriculture developments.

In 2018 BASEflow identified a pilot area, Jordan Village in Blantyre Rural district to start the field based pilot programme. The area shows good potential for agriculture developments, and importantly is located in a basin with known artesian groundwater pressure. There is an existing artesian borehole in the centre of the area, which has been flowing uncontrolled for 12 years. It is estimated that over 180 million litres of water have been discharged from this hole! Quite a large waste of groundwater resources! The team planned to use this existing borehole as the artesian water source for the pilot project, the only problem was that in its state, there was no way of properly controlling (or stopping) the flow. Therefore, the first stage of the programme was to inspect and test this borehole to see if it could be rehabilitated, utilised and securely capped, or if an alternate source would be required.

The process of inspecting and capping the borehole was delivered as an 'Artesian Borehole Capping Exercise' over one week, with attendees from Government departments, NGOs, Universities and drilling contractors. Before the field sessions started, a day was spent in the classroom, with sessions delivered by Nick Mannix on 'Understanding Artesian Groundwater - The Basics', 'Artesian flow control and capping' and finally a focus upon the Jordan test site.

The following days were spent at the Jordan test site, where the team thoroughly inspected and tested the borehole (including pressure testing using an inflatable packer), to ensure that flow from the borehole could be stopped without subsequent leaking, either from within or up the outside the existing casing. After 2 days of pressure testing (including an overnight pressure test), the hole was seen to be suitable for capping in its current state as the existing casing, and annulus fill were seen to be in good condition and able to hold the pressure. The borehole registered a pressure of 0.4bar (4 metres of head of water). The borehole was then capped at the head, with a temporary civil works installation (tap stand) installed. OG Madzi drilling contractor were engaged to work on the site, as they had previously worked with University of Strathclyde to cap another artesian borehole in 2016 and have knowledge of the works required.

Now the water source has been controlled and secured, the next step is to develop the plans for the sustainable agriculture developments in the area (including drip irrigation and potential fish farming). Once plans are in place, the artesian borehole will be formally connected up to the new agriculture systems.

[1] Another article about this project has been written by Baseflow and can be found here

#Artesian #Baseflow #Borehole #Workshop

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