Wells 1 Marco Bruni, seecon international gmbh. Wells Find this presentation and more on: Copy it, adapt it, use it – but

Wells

Wells

1

Marco Bruni, seecon international gmbh

Wells

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Depending on the initial situations and respective local circumstances, there is no guarantee that single measures described in the toolbox 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 ideas for improving the local water and sanitation situation in a sustainable manner. Results depend largely on the respective situation and the implementation and combination of the measures described. An in-depth analysis of respective advantages and disadvantages and the suitability of the measure is necessary in every single case. We do not assume any responsibility for and make no warranty with respect to the results that may be obtained from the use of the information provided.

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Wells


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

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Variability of the Groundwater Table

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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

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Groundwater Withdrawal from Wells by Means of Buckets or Pumps

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1. Introduction

Source: IWMI (n.y.); NE (n.y.); WATER CHARITY (n.y.); BAUMANN (2011)

PumpsPumps

Rope & BucketRope & Bucket

Source: http://www.flickr.com/photos/foodforthepoor/6100218694/sizes/z/in/photostream/ [Accessed: 17.05.2012]

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Health Aspects

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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

High quality drinking water

No or just minor purification

required

No or just minor purification

required

Many low-cost and low-tech digging and

drilling options available

Many low-cost and low-tech digging and

drilling options available

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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.

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3. Prospecting for Groundwater Sources

Source: http://thumbs.dreamstime.com/thumblarge_553/1288894832745DF3.jpg [Accessed: 18.05.2012]

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Two Main Types of Wells

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4. Different Types of Wells and their Performance

Dug WellsDug Wells Drilled WellsDrilled Wells

Diameter: +/- 1.2mLength: 3 – 20m

Diameter: +/- 50mmLength: 10 – 50m (200m)

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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

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Source: BUCHANAN et al. (2010)

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Dug Well: Elements

10


Source: SMET & WIJK (2002)

Well HeadWell Head

Well ShaftWell Shaft

IntakeIntake

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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.

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Source: : http://cloud.globalgiving.org/pfil/7109/Handdug_Well2_Grid7.jpg [Accessed: 14.03.2011]

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Drilled Well: Drilling

a) Basic hand-drilling techniques

b) High-tech machine-drilling

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Source: http://www.nigerwaterforlife.org/images/upload/IMAG0010.jpg [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]

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Drilled Well: Drilling – Many Different Techniques

a) Basic Hand-drilling techniques

b) Machine-drilling

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Source: ELSON & SHAW (1995)

Source: WURZEL (2000)

Augering

Jetting

Sludging

Percuss

i

on

Machine-

drillin

g

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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)

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Source: WATERAID (2008)

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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

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Source: NABUUR (n.y.)

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Dug Well

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• 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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Drilled Well

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• 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.jpg [Accessed: 18.05.2012]

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Drilled Well Drilled Well

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• 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

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Dug Well

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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


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Drilled Well

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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


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9. ReferencesBAUMANN, 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].

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Wells 1 Marco Bruni, seecon international gmbh. Wells Find this presentation and more on: Copy it, adapt it, use it – but