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[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages]] >> [[Developing groundwater resources | Developing groundwater resources]] / [[Groundwater development techniques | Groundwater Development Procedures]] >> Borehole Drilling
 
[[Africa Groundwater Atlas Home | Africa Groundwater Atlas]] >> [[Additional resources | Resource pages]] >> [[Developing groundwater resources | Developing groundwater resources]] / [[Groundwater development techniques | Groundwater Development Procedures]] >> Borehole Drilling
 
  Please cite page as: Africa Groundwater Atlas. 2019. Borehole Drilling. British Geological Survey. Accessed [date you accessed the information]. ''Weblink''.
 
  
 
   This page is still in development - please check back soon for updates.
 
   This page is still in development - please check back soon for updates.
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There are two main approaches to drilling boreholes : drilling with a mechanised rig; and manual drilling. The most appropriate technique will depend on the hydrogeology, the required yield, and available funds.  
 
There are two main approaches to drilling boreholes : drilling with a mechanised rig; and manual drilling. The most appropriate technique will depend on the hydrogeology, the required yield, and available funds.  
  
An introduction to borehole drilling techniques that are appropriate for rural water supply can be found in the chapter '''Designing and constructing water points''' in [https://www.developmentbookshelf.com/doi/book/10.3362/9781780441290 MacDonald et al. (2005)], which can be freely downloaded online.
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An introduction to borehole drilling techniques that are appropriate for rural water supply can be found in the chapter [https://www.developmentbookshelf.com/doi/abs/10.3362/9781780441290.006 '''Designing and constructing water points'''] in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)], which can be freely downloaded online.
  
 
===Drilling with a rig===
 
===Drilling with a rig===
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There are two main motorised drilling techniques: cable tool percussion (also known as shell and auger); and rotary drilling. Rotary is the most common method used for water borehole drilling. Rotary drilling can be air flush, sometimes with down-the-hole hammer; mud flush; or reverse circulation.  
 
There are two main motorised drilling techniques: cable tool percussion (also known as shell and auger); and rotary drilling. Rotary is the most common method used for water borehole drilling. Rotary drilling can be air flush, sometimes with down-the-hole hammer; mud flush; or reverse circulation.  
 
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[[File:AP1040881.JPG |thumbnail| 400px| center| Drilling a water borehole with a rotary rig in Northern Region, Ghana. Photo credit: British Geological Survey.]]
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[[File:AP1040881.JPG | 400px| center| Drilling a water borehole with a rotary rig in Northern Region, Ghana. Photo credit: British Geological Survey.]]
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===[[Manual drilling | Manual drilling]]===
 
===[[Manual drilling | Manual drilling]]===
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A separate Atlas resource page on [[Manual drilling | '''manual drilling''']] provides more information and resources.
 
A separate Atlas resource page on [[Manual drilling | '''manual drilling''']] provides more information and resources.
 
[[File:ManualDrillingChad.png|thumb| 400px|center| A manual drilling operation in Chad, using the sludging method. Image credit: [https://www.unicef.org/wash/files/CHAD_Case_Study_Aug14_lowRes.pdf PRACTICA Foundation 2009]]]
 
  
 
==Drilling Supervision==
 
==Drilling Supervision==
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Whichever drilling technique is used, collecting data during drilling is a very important part of successful groundwater development. Drilling is usually the only opportunity to look below the ground and find out what the geology and hydrogeology is at depth, where it is usually hidden. One of the main aims is to identify groundwater-production zones at depth in the geological sequence – at what depths is groundwater found? Data on the local geology is also invaluable for developing understanding. It is good practice for the drilling supervisor (see above) to collect data during drilling.  
 
Whichever drilling technique is used, collecting data during drilling is a very important part of successful groundwater development. Drilling is usually the only opportunity to look below the ground and find out what the geology and hydrogeology is at depth, where it is usually hidden. One of the main aims is to identify groundwater-production zones at depth in the geological sequence – at what depths is groundwater found? Data on the local geology is also invaluable for developing understanding. It is good practice for the drilling supervisor (see above) to collect data during drilling.  
  
A good introduction to what data to collect during drilling, and how best to collect it, is in the chapter '''Designing and Constructing Water Points''' in [http://dx.doi.org/10.3362/9781780441290 MacDonald et al. (2005)], which can be freely downloaded online.
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A good introduction to what data to collect during drilling, and how best to collect it, is in the chapter [https://www.developmentbookshelf.com/doi/abs/10.3362/9781780441290.006 '''Designing and constructing water points'''] in [http://nora.nerc.ac.uk/501046/ MacDonald et al. (2001)], which can be freely downloaded online.
 
 
The activities in the table below are a summary of good practice in data collection during water borehole drilling.
 
  
[[File:P1040701.JPG |thumb| 300px| left|Drilling supervisor recording drilling penetration rates with stopwatch and notebook. Photo credit: British Geological Survey.]]
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[[File:P1040669.JPG |thumb| 300px| center|Drilling supervisor examining rock cuttings with a hand lens. Photo credit: British Geological Survey.]]
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[[File:P1040795.JPG | thumb|300px| right|Rock cuttings from drilling laid out in sequence to be geologically logged by drilling supervisor. Photo credit: British Geological Survey.]]
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[[File:P1040669.JPG | 300px| left |Photo credit: British Geological Survey.]]
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[[File:P1040701.JPG | 300px| center|Photo credit: British Geological Survey.]]
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[[File:P1040795.JPG | 300px| right|Photo credit: British Geological Survey.]]
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The activities in the table below are a summary of good practice in data collection during water borehole drilling:
  
 
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{| class = "wikitable"

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