wells

1. Wells
Wells
1
Marco Bruni, seecon international gmbh

2. Wells
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Contents
1. Introduction
2. How Can Wells Optimise my Local Water System?
3. Prospecting for Groundwater Sources
4. Different Types of Wells and their Characteristics
5. Basic Design and Construction Principles
6. Operation and Maintenance
7. Applicability
8. Advantages and Disadvantages
9. References
2

3. Wells
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Variability of the Groundwater Table
3
1. Introduction
Source: SMET & WIJK (2002)
Infiltration of water into
an aquifer during the
wet season
Infiltration of water into
an aquifer during the
dry season

4. Wells
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Groundwater Withdrawal from Wells by Means of Buckets or Pumps
4
1. Introduction
Source: IWMI (n.y.); NE (n.y.); WATER CHARITY (n.y.); BAUMANN (2011)
Pumps
Rope & Bucket
Source:
http://www.flickr.com/photos/foodforthepoor/61002
18694/sizes/z/in/photostream/ [Accessed:
17.05.2012]

5. Wells
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Health Aspects
5
2. How Can Wells Optimise my Local Water System?
Source: BAUMANN (2011)
A properly constructed well can improve a community’s water
supply substantially.
High quality
drinking water
No or just minor
purification
required
Many low-cost and low-
tech digging and drilling
options available

6. Wells
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Where Should I Look for Groundwater?
• Villagers and members of the neighbouring
communities can be a good source of information
on the presence of shallow groundwater.
• Also, certain types of vegetation (e.g. banana plants, bulrushes,
sugar can, date palms) can indicate presence of groundwater
(COLLINS 2000).
• Often, existing wells in close proximity indicate the presence of
groundwater.
• If technical equipment is available, test borings can give detailed
information on the groundwater level.
6
3. Prospecting for Groundwater Sources
Source:
http://thumbs.dreamstime.com/t
humblarge_553/1288894832745DF
3.jpg [Accessed: 18.05.2012]

7. Wells
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Two Main Types of Wells
7
4. Different Types of Wells and their Performance
Dug Wells Drilled Wells
Diameter: +/- 1.2m
Length: 3 – 20m
Diameter: +/- 50mm
Length: 10 – 50m (200m)

8. Wells
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Location
• Wells should not be constructed close to potential sources of
contamination, e.g. pit latrines, livestock farming, fuel/pesticide/
fertiliser storage, etc.
• Well should be located in close proximity to the actual point of
water use
8
5. Basic Design and Construction Principles
Source: BUCHANAN et al. (2010)

9. Wells
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Dug Well: Elements
9
5. Basic Design and Construction Principles
Source: SMET & WIJK (2002)
Well Head
Well Shaft
Intake

10. Wells
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Dug Well: Excavation
• Excavation is done
manually with pick and
shovel
• Lining is most often
necessary to protect the
well from collapsing and
preventing subsequent
contamination of the well
• Materials for lining:
prefabricated concrete
rings, stones, bricks,
masonry, etc.
10
5. Basic Design and Construction Principles
Source: : http://cloud.globalgiving.org/pfil/7109/Handdug_Well2_Grid7.jpg [Accessed:
14.03.2011]

11. Wells
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Drilled Well: Drilling
a) Basic hand-drilling techniques
b) High-tech machine-drilling
11
5. Basic Design and Construction Principles
Source:
http://www.nigerwaterforlife.org/images/upload/IMAG0010.j
pg [Accessed: 27.03.2012]
Source:
http://i01.i.aliimg.com/photo/v0/106324951/water_well_drilling
_and_borehole_rig_machine.jpg [Accessed: 17.05.2012]

12. Wells
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Drilled Well: Drilling – Many Different Techniques
a) Basic Hand-drilling techniques
b) Machine-drilling
12
5. Basic Design and Construction Principles
Source: ELSON & SHAW
(1995)
Source: WURZEL (2000)

13. Wells
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Drilled Well: Completion
Completion of a well involve construction of a:
• Well casing (prevents the well from
collapse and seepage of contaminants).
• Well screen (holds back sediments while
allowing water to infiltrate the well)
• Gravel pack (prevents the well screen from
becoming clogged)
• Sanitary seal & head works (prevents
surficial contamination)
13
5. Basic Design and Construction Principles
Source: WATERAID (2008)

14. Wells
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Well Protection
• Wells and aquifers are susceptible to contamination. Contaminants
can either enter from the opening or from the sides of the
excavation.
• Water source protection involves:
 Interdiction of all activities that can potentially cause
contamination close to the well (e.g. pit latrines, livestock
farming, fuel/pesticide/ fertiliser storage, etc)
• Wellhead protection involves:
 Drainage
 Surficial seal: an apron
 Impermeable lining (dug wells) or
casing (drilled wells)
 Securing functioning of the pump
14
5. Basic Design and Construction Principles
Source: NABUUR (n.y.)

15. Wells
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Dug Well
15
• Structural maintenance includes:
 Checking the apron for cracks,
 Securing the inspection cover, Improving the yield by
deepening or removing infiltrated sand particles, and the
 Maintenance of the lifting device.
• Equally, securing hygienic operation is essential. This
involves:
 Protection and cleaning of the area (e.g. fencing and
covering),
 Checking water quality and disinfecting if necessary,
 Monitoring the effects of withdrawal on environment and
surrounding areas, and
 Educating water users in proper operation of the well.
6. Operation and Maintenance

16. Wells
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Drilled Well
16
• Drilled wells are easy to operate and basically not in need for
maintenance.
• However, as a drilled well always include a manual or
mechanised pump, maintenance of the lifting is critical!
6. Operation and Maintenance
Source:
http://www.edgeoutreach.com/sites/edgeoutreach.com/files/HaitiHPRTrainers.j
pg [Accessed: 18.05.2012]

17. Wells
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Drilled Well Drilled Well
17
• Can serve as a water supply for a
rural community, depending on
the performance
• Low-tech solution  particularly
for rural communities
• Can serve as water supply for
single households, for small
rural communities as for more
urban areas, depending on the
size of the well (depth &
diameter).
• Manual drilling is applicable in
alluvial soils up to 40 metres.
• A pump must be available and
frequently maintained
7. Applicability

18. Wells
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Dug Well
18
Advantages:
•High degree of involvement of the
local community during the whole
process
•Under supervision, no skilled workers
are required
•Simple equipment sufficient for both
construction and maintenance
•Low cost for construction and O&M
•Involvement of private sector possible
(local well diggers)
•Yield can be increased after
construction
•Reservoir included (large diameter)
Disadvantages:
• Long construction phase
• Dangerous excavation
• Motorised pump (power source)
often required to lower the water
table during construction
• Application restricted to regions
with rather soft geological
formation and relatively high
groundwater levels
• Alteration of groundwater level
can adversely affect the
surrounding environment
• High susceptibility for
contamination
• People (i.e. children) can fall in if
the well is uncovered
8. Advantages and Disadvantages

19. Wells
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Drilled Well
19
Advantages:
• Quicker and cheaper to sink than
hand-dug wells
• Less susceptible to contamination
• No dewatering during sinking
required
• Less lining material required
• Safer in construction and use
• The well itself needs barely
maintenance
• Many simple drilling techniques
available suiting many geological
conditions
Disadvantages:
• Skilled staff and experts required
for drilling
• Pump required, which needs
appropriate operation and
maintenance
• Lower yield than hand-dug wells
(smaller diameter)
• Overexploitation may lead to
adverse effects on the
environment
• Arsenic pollution may occur
• More technical equipment and
skills necessary for construction
• No integrated storage capacity /
recharge during periods of low
abstraction
8. Advantages and Disadvantages

20. Wells
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20
9. References
BAUMANN, E. (2011): Low-cost Hand Pumps. St. Gallen: Rural Water Supply Network (RWSN). URL:
http://www.rwsn.ch/documentation/prcollector.2009-04-05.2482958002/skatdocumentation.2011-07-01.0268979788/file
[Accessed: 02.04.2012].
BUCHANAN, B.; DE LA CRUZ, N; MACPHERSON, J.; WILLIAMSON, K. (2010): Water Wells that Last for Generations. Edmonton:
Alberta Agriculture and Rural Development. URL: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/wwg404
[Accessed: 23.04.2012].
ELSON, B.; SHAW, R. (1995): Simple Drilling Methods. Leicestershire: Water, Engineering and Development Centre (WEDC),
Loughborough University. URL: http://www.lboro.ac.uk/well/resources/technical-briefs/43-simple-drilling-methods.pdf
[Accessed: 21.03.2012].
IWMI (n.y.): Diesel pump in operation. Colombo: International Water Management Institute (IWMI). URL: http://awm-
solutions.iwmi.org/motorized-pumps.aspx [Accessed: 25.04.2012].
NABUUR (n.y.): Protected dug well in Uganda. Amersfoort: Nabuur. URL:
http://www.nabuur.com/en/village/nakyerongosa/project/task/integrated-community-managed-water-hygiene-and-sanitation-
improvem [Accessed: 15.03.2012].
NE (n.y.): Solar Water Pump. Lahore: National Engineers (NE). URL:
http://www.ne.com.pk/uploads/images/Gallery/pump/DSCN0054.jpg [Accessed: 26.04.2012].
SMET, J. (Editor); WIJK, C. van (Editor) (2002): Small Community Water Supplies: Technology, People and Partnership:
Groundwater Withdrawal - Chapter 10. The Hague: International Water and Sanitation Centre (IRC). URL:
http://www.irc.nl/page/1917 [Accessed: 29.02.2012].
WATERAID (2008): Technology Notes. London: Wateraid. URL:
http://www.wateraid.org/documents/plugin_documents/technology_notes_2008.pdf [Accessed: 12.03.2011]
WATER CHARITY (n.y.): Deep-well hand piston pump including apron and drain in Wallalan, Upper Badibu District, Gambia.
Crestline: Water Charity. URL: http://appropriateprojects.com/images/jorgensen/7.jpg [Accessed: 02.04.2012].
WURZEL, P. (2001): Drilling Boreholes for Handpumps. St. Gallen: Swiss Centre for Development Cooperation in Technology and
Management (SKAT). URL: http://www.skat.ch/publications/prarticle.2005-09-29.5069774463/prarticle.2006-11-
02.5180575226/skatpublication.2006-11-02.0404244520/file [Accessed: 22.03.2012].