Wells
Marco Bruni, seecon international gmbh
Wells
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will make the local water and sanitation system more sustainable. The main aim of the SSWM Toolbox is to be a reference tool to provide
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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
Wells
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1. Introduction
Variability of the Groundwater Table
Infiltration of water into
an aquifer during the
wet season
Infiltration of water into
an aquifer during the
dry season
Source: SMET & WIJK (2002)
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1. Introduction
Groundwater Withdrawal from Wells by Means of Buckets or Pumps
Pumps
Source:
http://www.flickr.com/photos/foodforthepoor/61002
18694/sizes/z/in/photostream/ [Accessed:
17.05.2012]
Source: IWMI (n.y.); NE (n.y.); WATER CHARITY (n.y.); BAUMANN (2011)
Rope & Bucket
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2. How Can Wells Optimise my Local Water System?
Health Aspects
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 lowtech digging and drilling
options available
Source: BAUMANN (2011)
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3. Prospecting for Groundwater Sources
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.
Source:
http://thumbs.dreamstime.com/t
humblarge_553/1288894832745DF
3.jpg [Accessed: 18.05.2012]
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4. Different Types of Wells and their Performance
Two Main Types of Wells
Dug Wells
Diameter: +/- 1.2m
Length: 3 – 20m
Wells
Drilled Wells
Diameter: +/- 50mm
Length: 10 – 50m (200m)
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5. Basic Design and Construction Principles
Location
• Wells should not be constructed close to potential sources of
contamination, e.g. pit latrines, livestock farming, fuel/pesticide/
fertiliser storage, etc.
Source: BUCHANAN et al. (2010)
• Well should be located in close proximity to the actual point of
water use
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5. Basic Design and Construction Principles
Dug Well: Elements
Well Head
Well Shaft
Intake
Source: SMET & WIJK (2002)
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5. Basic Design and Construction Principles
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.
Wells
Source: : http://cloud.globalgiving.org/pfil/7109/Handdug_Well2_Grid7.jpg [Accessed:
14.03.2011]
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5. Basic Design and Construction Principles
Drilled Well: Drilling
a) Basic hand-drilling techniques
Source:
http://www.nigerwaterforlife.org/images/upload/IMAG0010.j
pg [Accessed: 27.03.2012]
b) High-tech machine-drilling
Wells
Source:
http://i01.i.aliimg.com/photo/v0/106324951/water_well_drilling
_and_borehole_rig_machine.jpg [Accessed: 17.05.2012]
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5. Basic Design and Construction Principles
Drilled Well: Drilling – Many Different Techniques
a) Basic Hand-drilling techniques
Source: ELSON & SHAW
(1995)
b) Machine-drilling
Source: WURZEL (2000)
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5. Basic Design and Construction Principles
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)
Source: WATERAID (2008)
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5. Basic Design and Construction Principles
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
Wells
Source: NABUUR (n.y.)
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6. Operation and Maintenance
Dug Well
• 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.
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6. Operation and Maintenance
Drilled Well
• 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!
Source:
http://www.edgeoutreach.com/sites/edgeoutreach.com/files/HaitiHPRTrainers.j
pg [Accessed: 18.05.2012]
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7. Applicability
Drilled Well
Drilled Well
• Can serve as a water supply for a • Can serve as water supply for
single households, for small
rural community, depending on
rural communities as for more
the performance
urban areas, depending on the
• Low-tech solution  particularly
size of the well (depth &
for rural communities
diameter).
• Manual drilling is applicable in
alluvial soils up to 40 metres.
• A pump must be available and
frequently maintained
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8. Advantages and Disadvantages
Dug Well
Advantages:
Disadvantages:
•High degree of involvement of the
local community during the whole
process
•
Long construction phase
•
Dangerous excavation
•Under supervision, no skilled workers
are required
•
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
•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)
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8. Advantages and Disadvantages
Drilled Well
Advantages:
Wells
Disadvantages:
•
Quicker and cheaper to sink than
hand-dug wells
•
•
Less susceptible to contamination
Skilled staff and experts required
for drilling
•
No dewatering during sinking
required
•
Pump required, which needs
appropriate operation and
maintenance
•
Less lining material required
•
•
Safer in construction and use
Lower yield than hand-dug wells
(smaller diameter)
•
The well itself needs barely
maintenance
•
Overexploitation may lead to
adverse effects on the
environment
•
Many simple drilling techniques
available suiting many geological
conditions
•
Arsenic pollution may occur
•
More technical equipment and
skills necessary for construction
•
No integrated storage capacity /
recharge during periods of low
abstraction
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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://awmsolutions.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-sanitationimprovem [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.2006-1102.5180575226/skatpublication.2006-11-02.0404244520/file [Accessed: 22.03.2012].
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“Linking up Sustainable Sanitation,
Water Management & Agriculture”
SSWM is an
initiative
supported by:
Created
by:
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