Hand Drilled Wells 1984

136 Pages·1984·6.02 MB·English

AT

MICROFICHE
REFERENCE
LIBRARY
A project of Volunteers in Asia

By: Sob Blankwaardt

Published by:
Rwegarulila Water Resources Institute
P.O. Box 35059
Dar es Salaam, Tanzania

Available from: TOOL Foundation
Entrepotdok 68aI69a
1018 AD Amsterdam
The Netherlands

Reproduced with permission.

Reproduction of this microfiche document in any form is subject to the same
restrictions as those of the original document.

I

Hand Drilled Wells

A Manual on Siting, Design, Construction
anti Maintenance

Hand Drilled Wells

A Manual on Siting, Design, Construction
and Maintenance

Bob Blankwaardt

Rwegaruli!a Water Resources Institute

t

The preparation and printing of this publication h;; been made possible by grants from the
United P!ations Children’s Fund (UNICEF) and the Swedish International Development
Agency (SIDA).

0 1984 Bob Blankwaardt

ISBN
9976 936 01 X

Published by the Rwegarulila Water Resources Institute,
P-0. Box 35059, Dar es Salaam, Tanzania

Layout and cover design by Lees Doikens, Illugrafika, Den Haag

Drawings by the author

Photography by Rwezaula J. Kabengula.
Library Photographic Unit, University of Dar es Salaam

Typeset and printed in the Netherlands by
Roeland Foto-Offset B.V., Den Haag

Distribution overseas by TOOL Foundation,
Entrepbtdok 68A/69A,
1018 AD Amsterdam, the Netherlands.

Copyright
is reserved under Protocol 2 of the Universal
Copyright
Convention.
Nevertheless,
permission is hereby
granted for reproduction
of this material,
in whole or part, for educational,
scientific
or development-related
purposes, except those involving
commercial
sale, provided
that a) full citation
of the source is given and b)
notiticaiion
in writing is given to the Rwegarulila
Water Resources Institute.

Foreword

We, at the Rwegarulila Water Resources Institute, are very happy with tlx publication of this
handbook.
In trying to opt for least cost altemstives in providing our people with clean drinking water
and hygienic sanitation, the Ministry of Water, Energy and Minerals directed the Institute to
give priority to local resources technology in its craft and technical curriculum.
Training in Shallow Wells Technology has been included in our three year Full Technician
Programme. While meaningful development in this direction has been achieved, lack of
performance oriented instructional materials has been cur major setback. The publication of
this handboek is timely. It is indeed an invalu&le input into our training system.
For those involved in the construction and maintenance of tube wells at community level this
handbook will be of much help.

Washington Mutayoba

Principal
Rwegarulila Water Resource Institute

Foreword

We, at the Rwegarulila Water Resources Institute, are very happy with thz publication of this
handbook.
In trying to opt for least cost alternatives in providing our people with clean drinking water
and hygienic sanitation, the Ministry of Water, Energy and Minerals directed the institute to
give priority to local resources technology in its craft and technical curriculum.
Training in Shallow Wells Technology has been included in our three year Full Technician
Programme. While meaningful development in this direction has been achieved, lack of
performance oriented instructional materials has bean Gur major setback. The publication of
this handboek is timely. It is indeed an invalua’ole input into our training system.
For those involved in the construction and maintenance of tube wells at community level this
handbook will be of much help.

,

Washington Mutayoba

Principal
Rwegarulila Water Resource Institute

Preface and Acknowledgements

This Manual on Hand Driiled Wells is the product of 3 years’ field and classroom teaching experience,
Brst at the Morogoro Wells Construction Project and later at the Rwegarulila Water Resources
Institute. When I was asked to prepare the manual I accepted the task with enthusiasm, but I was
imediately
confronted with a problem. Although primarily meant for pre-service students at the
Institute, the book should, at the same time, serve a much bwader public including craflsmen,
technicians and practising engineers, and also project planners, 1 have tried to solve this problem by
writing a kind of refewnce book with some features of a “true” manual in the sense that the most
important operations have been described as step-by-step procedures and illustrated with many
drawings and photographs. However, since I am convinced that practical skills can only be improved
by theoretical knowledge. I have included more background information than strictly required for a
manual.
i reaiize that by writing in the English language, 1 will not reach the entire group o.*people involved in
well construction. Particularly for the in-service training courses which are ma,~dy followed by
craftsmen with primary education only, and in view of the strongly recommended village level
operation and maintenance of water supply systems, a translation in due course of relevant parts of the
book into Kiswahili remains a task of high priority.
The manual is built up in six parts. The lirst part - Chapter 1 - is an introduction to the subject. In the
second part - Chapters 2 and 3 - the nost necessary hydrogeological theory is given. Part three which
includes Chapters 4 and 5, deals uith site investigation and the criteria for approving a site for
construction of a well. In part four - Chapter 6 - the design of the well is discussed, and in part five
- Chapters 7 to I I - the actual construction of the well including the installation of a hand pump. In
the last part - Chapter I2 - a possible approach towards the maintenance of pumps and wells is
indicated. In order to keep the siz.? of rhe chapters on site investigation and well drilling operations
limited, the survey and well drilling equipment have been described in seperete appendices.
In the course of reading this manual, the realization of a well can be followed with the help of an
actual example from Chamazi village near Dar es Salaam. I am much indebted to the people of this
village for their hospitality. In fact, this village has virtually become a permanent training ground for the
Institute. Most of the photographs were taken here.
Publication of this manual Nould not have been possible without the continuous encouragement of
Washington Mutayoba. the Principal of the Institute, and the teaching statf: Elnathan M. Mundo.
John T. Sambu. Juma M. Kaeje and Abdallah S. Bunga, who gave me good advice on the desired
content of the book.
1 am very grateful to the following persons for their invaluable contributions.
- My former colleagues in the Morogoro Wells Construction Project, especially Aat van der Wel
who read an early version and made very helpful comments.
-
The Organization of Netherlands Volunteers for giving me the opportunity to finalize this work,
- Abubakr Kigingi, executive engineer in the Morogoro Regional Water Engineer’s ofice, Frans van
der Laak and Geert van den Honing of the Morogoro Wells Construction Project, Hartmut Floegel
of the Tanga Integrated Rural Development i’roject and Jo Smet of the Community Health
Department, Faculty of Medicine. University of Dar es Salaam, for their critical review of several
chapters.
- Daphne Beaton and Malcolm Norris of the Communication Skills Unit, University of Dar es
Salaam, for their patient and undaunted correction of my English.
- Helen Cramer, for typing the first version and large parts of the final manuscript.
To Peter van der Werff, an old friend of mine, I owe special thanks for all his tireless work behind
the scenes.

Bob Blankwaardt

VI

Dar es Salaam, April 1984

VII

Contents

Chapter 1 Introduction

I. 1 Comparison of water supply systems
1.2 Hand drilled wells: a short description
I .3 Hand drilled wells versus dug wells

I
2
3

Chapter 2 Groundwater

2.1 The hydrological cycle
2.2 Types of aquifers
2.3 Characteristics of aquifers
2.4
Basic well hydraulics
2.5 Groundwater level fluctuations

Chapter 3 Origin and occurrence of unconsolidated sediments

3.1 The process of weathering
3.2 Slope erosion
3.3 Erosion and sedimentation by rivers
3.4 The search for aquifers

Chapter 4
Site investigation

4.1
preparations in the offtce
4.2
Preparatory work in the village
4.3 Test urilling operations
4.4
Survey pump test
4.5
Description of soil samples
4.6
Drawing a section
4.7
Recording and storage of survey data

Chapter 5 Criteria for borehole approval

5. I
Test yield criterion
5.2 Water quality criteria
5.3
Hydrogeological criteria
5.4
Summary

Chapter 6 The design of tube wells

6.1 Components of a tube well
6.2
Design principles
6.3
Example of a design

Chapter 7 Well drilling operations

7.1 Preparations
72. Drilling without a casing
7.3 Installation of casing and bailing
7.4 Drilling inside the casing
7.5 Completion of the borehole
7.6 Telescopic drilling
7.7 Borehole description

12
13
13
17

21
22
23
26
27
29
31

33
34
35
36

37
37
40

41
42
44
46
46
47
48

VIII

Chapter 8 Installation of filter pipe and gravel pack

8.1 The gravel
8.2 The filter pipe
8.3
Installation of the filter pipe
8.4
Installation of the gravel pack
8.5
Methods of removing the casing

Chapter 9 Development, pump test and backfilling

9. I
Objectives of development
9.2 Overpumping
9.3
Surging
9.4
Pump test
9.S What to do if the pump test fails
9.6 Clay seals and backfill

Chapter 10 Construction of the slab

10.1 Design of the slab
10.2 Building materials
IO.3
Building the slab

Chapter 11 Hand pumps and their installation

I I. I
Choosing an appropriate pump
l I .2 Pumps in Tanzania
I I .3 Cylinder, rising main and pumprod
1 I .4 Installation of the pump

Chapter 12 Maintenance of pumps and wells

12. I
Towards village level operation and maintenance
12.2 Village maintenance tasks
12.3 The role of MAJI in well maintenance

References

Appendices

A
Prevention of water-related diseases
B Surveying equipment
C
Water quality standards
D
Well drilling equipment
E Topographical maps
F Checklist for pump maintenance
G
Disinfection of a well

Annexes

1 Village Sketchmap
2 Situation Sketchmap
3 Survey Borehole Description Form
4 Well Description Form
5 Maintenance report
6
Educational posters

Index

49
50
51
52
54

56
56
57
58
58
59

61
63
64

68
68
70
72

76
79
80

82

85
87
96
99
107
114
116

117
119
121
123
12.5
127

129

Chapter 1

Introduction

For the development of rural water supply the Tanzanian Government started the National Rural Water Supply
Programme in 197 I I and has adopted the United Nations’ Water and Sanitation Decade target: “To provide a
reliable water supply by the year 1991, whereby all people have ease of access (at a distance of 400 m or less) to a
pubiic domestic water point”. The ministry responsible for the planning, preparation and execution of this
programme is the Ministry of Water, Energy acd Minerals (MAJI).
The Government’s optimistic claim that currently 40 % of the rural population of 15 million people has access to
clean drinking water, might hold true if it were based on the installed capacity. However, taking into account the
water supply schemes that are out of order, probably not more than 3 million people at present have access to a
reliable supply. The remainder of the population is still (or again!) entirely dependent on the use of water from hand
dug holes, unprotected wells, rivers, pools, etc. The traditional picture of women fetching water of dubious quality at
places many miles from their homes is still the rule in the rural areas. Long walking distances also imply a low rate of
consumption. B&
Aa poor quality and the small quantity of water (often less than 10 litres per person per day) are
responsible tbr the spread i;f water-related diseases.
Assuming a growth rate of 3 96 per year, the total rural population will have grown to about 20 million people by the
year 1991. Consequently new water supply systems will have to be constructed, and old ones rehabilitaled. for 17
million people in 7 years’ time: that is to say, for around 2.5 million people per year, provided that none of the existing
or new supplies breaks down. In the present economic situation it is entirely beyond the country’s capabilities (even
with donor assistance) to provide every household with a tap inside the house. The country has to resort to low cost
technology which requires the least capital expenditure per head of population for investment, operation and
maintenance and at the same time guarantees a reliable and safe supply.

1.1 Comparison of water supply systems

Supply systems of the following types are commonly
constructed in the country:
- gravity-fed or pumped surface water;
- deep boreholes with motor-driven pumps:
- wells with hand pumps.
The features of these systems can briefly be described as
follows.

a) Surface water - pumped or gravity-fed - is generally
polluted. bacteriologically unsafe and carries a high
seasonal sediment load. Very often it needs treatment
which results in high investment and operational costs
and in a demand for skilled manpower.

b) For the construction of deep boreholes machine-
powered equipment is required. Even the simplest drill
rig requires skilled operators and high investment, and
its operation depends on the availability of fuel and
spare parts. Moreover, the exploration of deep ground-
water requires expensive geophysical investigations.

Both surface water and borehole supplies require capital
intensive distribution systems. These include pipelines,

break-pressure tanks. storage tanks and dcmestic water
points. The cost depends, of course, on the location of the
river intake or borehole and the size of the sillage
to be
supplied.

cl Tube wells and ring wells of shallow to medium depth
(often not quite correctly called “shallow wells”) can
be made hy hand drilling and digging respectively.
This leads to comparatively low investment costs.
Construction failures (lower yield than anticipated)
seldom occur if the location and the design of the wells
are based on the results of proper test drilling and
pumping. Operational costs are low because these
wells can be equipped with hand pumps, which do nor
require any fuel or highly skilled personnel. Moreover,
if maintenance is made the responsibility of the village,
mamtenance costs can be limited. In fact, centralized
maintenance may well be beyond the country’s
financial and organizational capabilities.

A comparison of estimated investment, operational and
maintenance costs of the various systems is given in Table
1.1.

1

HAND
DRILLED
WELLS

Table 1.1 Cost of water supply systems per head
of popuiation in T.Shs.

Type of supply
Investment
0 & M”)/year
.--
Gravity
600- 1200
10
Pumped surface water
600- 900
20
Deep borehole
600- 900
15
Concrete ring wellb)
loo- 150
5
Hand drilled tube