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SE 044 387
Water Purification, Distribution and Sewage Disposal.
Appropriate Technologies for Development. Reprint
R-29.
Peace Corps, Washington, DC.
and Exchange Div.
Apr 79
PC-25-1709
259p.; Prepared by Volunteers for International
Technical Assistance, Inc.
Peace Corps, Information Collection & Exchange,
Office of Programming and Training, 806 Connecticut
Avenue, NW, Washington, DC 20526.
Guides - Classroom Use - Guides (For Teachers) (052)
Information Collection
MFO1/PCll Plus Postage.
*Construction (Process); Design Requirements;
Developing Nations; Learning Activities;
Postsecondary Education; Public Health; *Toilet
Facilities; *Training Methods; Training Objectives;
Units of Study; *Waste Disposal; Waste Water; *Water
Resources; *Water Treatment
IDENTIFIERS
*Peace Corps; Water Distribution
ABSTRACT
This document, designed to serve as a training manual
for technical instructors and as a field resource reference for Peace
Corps volunteers, consists of nine units. Unit topics focus on: (1)
water supply sources; (2) water treatment; (3) planning water
distribution systems; (4) characteristics of an adequate system; (5)
construction techniques; (6) operation and maintenance of a
distribution and treatment system; (7) scope of disposal system
projects in host communities; (8) the privy method of excreta design
for a village; and (9) water carried sewage systems construction and
maintenance. Each unit includes: an overview (statement summarizing
significance of material to follow and points requiring special
emphasis); an objective (definition of goal to be achieved); lists of
tasks (steps followed to accomplish objectives), functional skills
(knowledge skills needed to perform tasks), terminal performance
tests; content information describing the knowledge and skills needed
to perform tasks correctly; and lesson plans. (JN)
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3
WATER PURIFICATION, DISTRIBUTION AND SEWAGE DISPOSAL
FOR
PEACE CORPS VOLUNTEERS
Prepared by
Volunteers for International Technical Assistance, Inc.
In accordance with Contract PC 25-1709
Reprinted by Peace Corps:
WS/Technical Resources Division-5/69
OPDER/Information Resource Services-11/69
Information Collection & Fxchange-4/79
TABLE OF CONTENTS
WATER SUPPLY SOURCES AND TREATMENT
SECTION 1: WATER SUPPLY SOURCES
GUENUI GMs ecb eeheew isaac eSbiss dee sasbasducteciacesgeaenes aeenenes 1
Background Information
EVRTMRCIOR OT DOUTCUE Ss ceiis cdetncs cekisecdvcenenets iheweeneeanesves
Factors Influencing the Quality of Water
The Quantity of Water
Types of Sources
DOVOTORIURG OF TUGRP SOUTEUE so nk ccacceeecrcctvecsdactasiese ebeees ‘
The Basic Requirements of a Water Supply
Selection of the Source of Supply........... Shawdeen dacovasensees
LESSON PLANS
SECTION 2
Basic Steps in Treating Water
Sample Designs for Treatment Systems
LESSON PLANS
SECTION 3 PLANNING THE DISTRIBUTION SYSTEM
QVERVIEN. .ccccncecnesdescces ish ened sac daudedstndecbecdeteacesecase 67
Design... .cdccsedacvevensadcsenvicsesetcesebxeedeveseseds ceeeuneceent
Existing Facilities
Size and Nature of the Community
System Capacity
Water Source
Proposed System
Financing the Project
LESION PLANE, coc uctecedeweccedecccéscvsccudessncvesnss seceueevss os
SECTION 4 CHARACTERISTICS OF AN ADEQUATE SYSTEM
OVERVIEW
Essential Components of an Adequate System
General Requirements for an Adequate System
Relationship of Distribution System to Community
Headloss and Distribution Systems
LESSON PLANS
SECTION 5
Concrete
Construction at the Source
Construction at the Pumping Station
Construction at the Storage Facility
Construction on Supply Line
LESSON PLANS
SECTION 6 OF “RATION AND MAINTENANCE
OVERVIEW
Water Source Maintenance and Inspection
Regulations for Installing New Service Connections...
Regulations for Cleaning the Distributions System
Inventorying for Operation in Emergencies
Types of Financial Statements for Smal] Waterworks
LESSON PLANS
SECTION 7
OVERVIEW
Public Health Importance of Excreta Disposal....... eeetedves«sevs
How Disease is Carried from Excreta
The Characteristics of an Adequate System...... jeuedbnen sonveeees
Possible Sanitary Measures in Rural Areas
Soil and Ground-Water Pollution
Location of Latrines and Other Excreta Disposal Facilities....... 172
Sludge Accumulation and the Life of a Pit Privy
Community Participation
Family Participation
Role of Health Department and Other Agencies
Public Versus Private Latrines
Human Factors
LESSON PLANS
SECTION 8 THE PRIVY METHOD OF EXCRETA DISPOSAL DESIGN FOR
A VILLAGE
OVERVIEW
The Sanitary Survey
The Pit Privy
Example Privy Designs
Latrine for Village Use
Thailand Water-Seal Privy
LESSON PLANS
SECTION 9 WATER CARRIED SEWAGE SYSTEMS CONSTRUCTION AND
MAINTENANCE
OVERVIEW
The Septic Tank
Operation and Maintenance
LESSON PLANS
BIBLIOGRAPHY
TABLE OF CONTENTS
FIGURES
Contour lines
Symbols for Topographic maps
Contouring from spot elevations
Plane Table mapping
Nomenclature of unconsolidated rocks
Turbidity test
Geological formations
Occurrence and distribution of sub-surface water
Shallow well in free water zone
Well tapping confined water
Direct intake, with hose on bottom of water source
Surface intake with hose buried in gravel-filled pit........ coke
Use of bucket on end of surface intake
Improvised dam for impounding smal] streams
Baffle dam for protecting inlet strainer
Float-type surface intake, with anchors
Gravel-filled gallery intake
Spring inlet
Typical dug well with suction pump
Finished drive point well
Trickling sand filter
Chlorination system
Chlorination system
Cistern catchment yield
Determine stream yield
Cross section of stream
Hydraulic Ram
Typical Installation of jet pump
Displacement Pump Operation
Elementary, single acting force pump
Centrifugal pumps
Pump size and horsepower requirement
Layout of a combination water system
Pipe flow calculation
Dead-end system
Loop system
Head Measurement
Distribution system layout
Concrete Calculator
Concrete mixing
Slump cone
Slump cone plans
Smal] intake structure
Ground level reservoirs
Typical spring collection-chamber for towns
Properly protected spring
Properly protected spring (II)
Elevated storage tank
Water-level indicator for elevated storage tanks
Storage tank
Manhole covers
Typical valve and box
Piping installation
Cistern filters
Chtorination system...
Boiler for potable water
Standard pipe fittings
Treatment system flow chart
Trensmission of disease from Excreta
Cesspool Lined with large stones
Seepage pit
Typical household septic tank
Typical layout of septic-tank system
Movemen. of poliution in underground water
Sludge accumulation in pit latrines
Privy designs ensuring privacy and separation of the sexes
Types of rrivy Shelters
Various parts of a sanitary. privy
Typical round and square bases
A hewn-log privy base
Latrine for village use
Inner form of latrine (top view)
inner form and steel rim in place
Latrine bow! mold
Views construction SUM TOF FRCP TOG sin on 6 kes eS hence sens 202
Views construction slab for latrine
Views construction slab for latrine
Views construction slab for latrine
Views construction slab for latrine
Views construction slab for latrine
The completed casting
Sketch of the completed privy
Backward flushing trap
Forward flushing trap
Bowl core handles
Privy frame
Privy slab outline
Methods of making percolation tests
Longitudinal section of single compartment concrete
septic tank
Concrete silo stave tank
Cover slab for septic tank
Concrete block tank
Closed or continuous tile system arrangement for level ground..
Serial distribution system arrangement for sloping ground
Typical distribution box
TABLE OF CONTENTS
TABLES
Classification of unconsolidated materials
Coagulation Residuals
Test for proper chlorination dosage
Conversion of ppm to ounces per 1,000 gal.
Advantages and disadvantages of various types of pumps
Average friction loss for water flowing through pipe
Allowance in equivalent length of pipe for friction loss
in valves and threaded fittings
Repair record chart
Maintenance chart of a G.M. diesel 71
Pit privy capacity for a family of five
Volume and depth for rural latrine
Distances from various sources to disposal facilities
Required absorption area for given percolation rates
Required capacities for septic tanks serving individual
dwellings
Required capacities for septic tanks serving camps and day
schools
Capacities, dimensions and materials for septic tanks..
Absorption trench area and spacffg
PREFACE
WATER PURIFICATION, DISTRIBUTION, AND SEWAGE DISPOSAL is designed to a
aid both the technical instructor as a training manual and the Peace
Corps Volunteer as a field resource reference. We hope that the man-
ual will help to turn out Volunteers who can perform effectively in
the field.
Each logical unit of instruction is sub-divided into the foltawing
categories:
OVERVIEW
OBJECTIVE
TASKS
FUNCTIONAL
SKILLS
TERMINAL
PERFORMANCE
TESTS
RELATED
INFORMATION
LESSON
PLANS
A statement summarizing the general significance of
the material to follow, and points requiring special
emphasis.
A definition of the goal to be achieved by the trainee
for that unit of instruction.
The steps to be followed to accomplish the objective.
The knowledge and skills needed to be able to perform
the tasks.
The means of evaluating the ability of the trainee to
perform the skills needed to complete the tasks in
order to accomplish the objective.
Content information describing the knowledge and skills
needed to perform the tasks correctly.
Suggested guidelines for providing instructional time
for the essential areas of each unit.
Although we have followed a typical pattern of presentation, offering
logical units of information, it is important to keep in mind that the
manual is to be used in preparing Volunteers for a program and that no
single unit can possibly stand alone. All are interrelated and need to
be included in a systematic presentation.
Its value as a reference tool
will come after the skills have been learned and the Volunteer is over-
seas. Once in the field, the objectives and tasks can be used by the
Volunteer as an outline description of how the project should proceed.
During the early stages of the project, valuable suggestions and opinions
were offered by VITA Volunteers, Yobert Fortman, James Patterson, Morton
Hilbert and Ramesh Patel.
To Union College students Robert Okello and Richard Sack who collected,
summarized, and organized the material into the manual's present format,
a most sincere vote of thanks.
Without their efforts, we would still be
in first draft stages.
For reviewing the final draft and offering sound suggestions for improve-
ment, Robert Ellis deserves a vote of thanks.
A deep bow to Ethel Carlson, who managed to keep all the horses on the
track, and Barbara Ille, who spent many hours trudging through first
draft scratchings.
Special appreciation is extended to Messrs. Richard Williams and Mike
Furst, United States Peace Corps, and Ken Kalb, Executive Director, VITA.
Without their vision, support and encouragement, this manual would not have
been written.
Finally, errors and oversights must be credited to...
Michael J. Glowacki
Project Coordinator
Schenectady, New York
April 18, 1969
ie
SECTION 1
WATER SUPPLY SOURCES
OVERVIEW:
The purpose of a water supply system is to distribute water to the locations
where it is needed. A source of water must be found which is adequate in
quantity and quality. An understanding of the geological properties of the
earth is necessary to recognize and evaluate the potential sources of water
for this system.
This section is planned to familiarize the student with these basic geologi-
cal properties. Also included is information on making topographic maps to
aid in this evaluation. This background knowledge is then used to describe
water sources and how they can be developed to provide potable and palatable
water for distribution by the water supply system.
The learning activities in this section are primarily field exercises. The
trainees will be in the field seeing actual examples of water sources. They
will examine samples of the various rock types. The emphasis should be on
individual participation. It is only through this experience that a trainee
will be able to again recognize suitable sources when he is overseas.
WATER PURIFICATION, DISTRIBUTION, ANN SEWAGE DISPOSAL
WATER SUPPLY SOURCES AND TREATMENT
SECTION 1: WATER SUPPLY SOURCES
OBJECTIVE: Locate and identify water supply sources and
determine potential feasibility as village or
rural water supply sources.
TASKS: 1. Procure existing topographic maps and sketches
of the area and consult people with a knowledge
of the same information ontthe types and loca-
tions of the sources.
2. Determine the location of any lakes or ponds,
cisterns, springs, rivers, or wells with re-
spect to the community.
3. Identify any lakes, ponds, rivers, springs,
wells, or cisterns.
4. Roughly sketch the topography between the
sources and the community.
5. Plot the location of any houses, livestock
grazing areas, privies, etc. on an existing
map or a simple sketch map.
6. Estimate by means of field determinations
and past records the amount and the variation
in the amount of water available from each
source.
7. Identify the nature and quantity of any
ohysical, bacteriological, and chemical
pollutants of each source.
8. Icentify the extent to which any developments
wou.d improve the quality or quantity of the
various potentially productive sources.
9. Determine the cost of developments for each
potential source.
FUNCTIONAL SKILLS:
1. Interpret and make simple topographic maps.
2. Use a compass.
3. Identify the various types of water supply
sources.
13
ate
WATER SUPPLY SOURCES (cont.)
4,
Identify the basic rock and soil types
and know the hydrological properties of
each.
Know what factors influence the quantity
of a given water supply source.
Know what factors influence the quality
of a given water supply source.
Identify physical pollutants (the extent
of chemical and bacteriological pollution
will be determined by laboratory analysis).
Identify what developments can significantly
reduce pollution or improve the yield of the
various water supply sources.
List the relative costs of various types of
source developments.
TERMINAL PERFORMANCE TESTS:
1.
Given a compass, draw a simple topographic
map of any proninent topographic features
such as a hill.
In a field exercise, correctly identify
the various types of water supply sources.
Correctly identify the basic rock and soil
types.
Correctly list the factors which influence
the quality and quantity of a given water
supply source, and the extent that each
factor influences that source as a water
supply consideration.
Given a number of water samples, correctly
identify all physical pollutants present in
each sample.
Opposite each type of water supply source,
correctly list the developments that may
improve its quality or quantity.
On a written examination list the relative
cost of aiven tyres of source developments.
14
WATER SUPPLY SOURCES AND TREATMENT
WATER SUPPLY SOURCES
BACKGROUND INFORMATION
TOPOGRAPHIC MAPPING
In planning a water distribution: or sewage disposal system, the
layout of the community with respect to any water supply sources
must be mapped. When no maps of an area are available, crude
sketch maps are sufficient. Such maps should indicate the
approximate placement of any man-made structures, livestock
grazing areas, water supply sources, and disposal systems.
Topographic Contouring
A topographic map is a means of illustrating, through the
use of contour lines, the shape of the ground surface. This
exercise involves the determination of ground relief (topography)
from points whose elevations above sea level are known.
The method is called “contouring from spot elevations". The
data might have been obtained by surveying with a plane table
and alidade, although modern topographic maps are made much
more easily and accurately by the stereoscopic plotting of
airphoto information.
Rules and hints in topographic contouring.
1. All points lying on a contour are of the same elevation
above (or below) a reference point. However, one contour
need not satisfy all the points of equal elevation; eg.
adjacent hilltops of similar relief might require sepz-
rate, closed contours each showing comparable levels.
Some contours may be cut by the edges of the map and appear
to be discontinuous but if the map be made large enough
every contour eventually closes on itself, becoming con-
tinuous.
With rare exceptions, the contour interval is constant for
the map area and is defined as the vertical distance be-
tween successive contours. The contour interval is stated
as part of the scale of the map so that the vertical dimen-
sion of the contoured surface has identity. Ten-foot,
twenty-foot, fifty-foot and 100-foot intervals are common.
The interval is selected to best show the shape of the sur-
face at the desired horizontal scale without requiring an
unnecessary, unreadable number of lines. The relief of the
area to be mapped also influences the choice of the contour
interval.
Contours do not cross. Such a situation would illustrate
an impossible ground surface shape. Contours are closely
spaced on steep slopes, and distantly spaced on gentle
slopes.
Closed depression contours are hachured on the lower
side. They are used when all points within the line
are below the level of the line. Obviously they are
only required to show depressions which are completely
surrounded by high ground. Gullies and river valleys
are not usually closed on the downstream side and
therefore are not illustrated by depression contours.
A depression contour takes its value from that of the
lowest, topographically adjacent regular contour.
In contouring guilies and valleys, the contours vee
in the upstream direction. Be careful to confine the
strean to the lowest part of its valley by passing
the stream through the notch of the vee.
Fig. 1 Contour Lines
Contours are broken where numbering jis necessary, to
improve readability.
The use of some degree of “artistic license” is recom-
mended in contouring. Do not attempt to just satisfy
the point data. Try to make the trend of a contour
reflect the trend of its neighboring contours.
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Fig. 2 Symbols for Topograph‘cal Maps
16
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Draw and label the contours every 100' (300, 400’, 500’, etc.)
2. Indicate with dashed line a divide; with dotted line an area of future
stream capture. Label the highest point A, the lowest point B.
3. Distinguish areas of high and low stream gradient, indicate direction
of flow of streams.
17
Genera]
In making a crude topographic sketch very little attention should
be paid to detail. Scale can be determined by pace, and direction
by a compass. Periodic sighting of a distant object in a path and
determination of its position relative to a present mark will serve
for proper orientation.
Determining Pace
Lay out a one hundred foot interval on level qround, an uphill,
and a downhill slope. If only a foot ruler is available, this may
be used to mark out three or four feet on a stick, and this stick
in turn used to measure the 100 feet. Being careful to work nor-
mally, the map maker then determines the number of paces over the
100 foot interval for each slope. By division, it is then possible
to find a number of feet in an average pace for uphill, leve’ and
downhill slopes.
Taking Bearings with the Compass
A bearing is the compass direction from one point to another. A
bearing is always in a unidirectional sense; for example, if the
bearing from A to B is N30W, the bearing from B to A can only be
S30E. To read accurate hearings, three things must be done; (1)
the compass must be leveled, (2) the point sighted must be centered
exactly in the siqhts, and (3) the needle must be brought to rest.
In a sketch map, contours are used only to show the relative differ
ences in elevation and the nature of the topography. It is unneces
sary to know the elevation of a aiven contour or to connect all of
them. Contours can be drawn arbitrarily to indicate that a hill is
steep, a stream runs in a qiven direction, the community is uphill
from a water source, etc. A realistic sketch map can be drawn by
estimating the relief of an area around a point and then proceeding
to a point on the periphery of this area. Plane table mapping may
prove more adequate when more detailed maps are required.
Map Making Usina a Plane Table
A description is aiven for the construction of serviceable maps
using a plane table. Such maps are valuable for irrigation, drain-
age and village layout plans.
Tools and materials needed are:
Plane Table
Paper
Pencil
Ruler
Pins
Tape measure (optional)
Spirit level (optional)
The first step is to decide on a scale for the map. This is
determined by judging the longest distance to be mapped and
the size of the map desired. It should be noted that the
map does not have to be made on a single sheet of paper but
can be spliced together when completed. As an example, if one
wanted a map 2 1/2 feet long *o portray an area whose major
distance is 1/2 mile, 2640 feet, then a scale of 100 feet to
the inch would be convenient.
Paper should be placed on the plane table and the plane table
oriented on or near some principal feature of the map, that is,
a path, road, creek street, etc. A pin should then be placed
vertically in the spot on the finished map where this location
4s desired. The plane table should be made level - by use of
a spirit level, if available. The table should be rotated to
a proper orientation, that is, so that the direction will ap-
pear on the finished map in the desired way. Now sight along
the first pin to another principal feature which is visible
from the table location (a bend in the road, a hill or any
feature that wili tie the map together), moving the second pin
into the line cf sight. A ruler may be used for this purpose
if it has a sighting edge or even a couple of pins stuck into
it. Now draw a line in t.~ airection defi.jicd by the two pins.
Measure the distance to the feature observed either by pacihg
or with a tape. Scale this distance along the line drawn,
starting at the initial pin. Repeat this process for other
principal features which may be seen from this location. When
this has been done, move the table to one of the points just
plotted, selecting one which will enable you to move over
the territory in a convenient fashion. For example, follow a
lane or creek or some feature which t’es things together. Set
up the plane table over this point and reorient the table. Do
this by putting pins into the map at the present and previous
locations. Next rotate the table so chat the pins line up with
the previous location. This procedur? in fact locates the line
joining the two locations on the map a the same direction as
the line exists in nature. Again fron ‘his new location map
in the desired features which can be corveniently sighted.
In this way the entire region to be ncaones may be covered in a
systematic way. If gaps appear or if more detail is needed,
you may go back and set up over some mapped feature, reorient
the map by sighting on a second feature, and proceed to map in
the detail.
An alternate procedure may he used in mapping features which
are not going to be used as plane table locations in the map-
ping process. This involves drawing a line in the direction
of each feature from two plane table locations. The intersection
of these two lines corresponding to a single feature locates the
feature on the map. As a result this avoids the necessity for
measuring distances. Note, however, that it is impossible to
avoid measuring the distances between plane table locations.
If a spirit level is available, it is possible to level the
plane table accurately, and using a ruler or other sighting
device, relative elevations may be plotted on the map. A stick
about six or eight feet long should be marked off in inches, and
the person holding the stick vertically can, by moving his fin-
ger, identify to the person sighting, the distance up from the
ground through which the line of sight passes.
ROCK FORMATIONS AND THEIR WATER-BEARING PROPERTIES
The rocks that form the crust of the earth are divided into three
classes:
Igneous--rocks* which are derived from the hot magma deep in the
earth. They include granite and other coarsely crystalline rocks,
dense igneous rocks such as occur in dikes and sills, basalt, and
other lava rocks, cinders, tuff, and other fragmental volcanic ma-
terials.
Sedimentary--rocks which consist of chemical precipitates and of
rock fragments deposited by water, ice, or wind. They include de-
posits of gravel, sand, silt, clay, and the hardened equivalents
of these--conglomerate, sandstone, siltstone, shale, limestone,
and deposits of gypsum and salt.
Metamorphic--rocks which are derived from both igneous and sedi-
mentary rocks through considerable alteration by heat and pres-~
sure at great depths. They include gneiss, schist, quartzite,
slate, and marble.
Fig. 4 PLANE TABLE MAPPING
The pores, joints, and crevices of the rocks in the zone of saturation
are generally filled with water. Although the openings in these rocks
are usually small, the total amount of water that can be stored in the
subsurface reservoirs of the rock formations is large. The most pro-
ductive aquifers* are deposits of clean, coarse sand and gravel: coarse
porous sandstones; cavernous limestones; and broken lava rock. Some
limestones, however, are very dense and unproductive. Most of the ig-
neous and metamorphic rocks are hard, dense, and of tow permeability.
They generally yield smal] quantities of water. Among the most unpro-
ductive formations are the silts and clays. The openings in these ma-
terials are too small to yield water, ard the formations are structur-
ally too incoherent to maintain large openings under pressure. Com-
pact materials near the surface, with open joints similar to crevices
in rock, may yield small amounts of witer.
EXAMPLES OF MIXED ROCK
Medium sand with fine gravel, gray Fine gravel 20%
Coarse sand, gray 30%
Medium sand, gray 40%
Fine sand, gray 10%
Medium gravel with coarse sand, brown Coarse Gravel, brown 20%
Medium gravel, brown 30%
Fine gravel, brown 20%
Coarse sand, brown 20%
Medium sand, brown 10%
Clay with sand and fine gravel, blue Fine gravel, gray 5%
Coarse sand, gray 5%
Medium sand, gray 10%
Fine sand, blue 20%
Clay, blue 60%
The nomenclature used in consolidated sedimentary rocks is very similar
to that used for the unconsolidated rocks. The following names should
be applied to the consolidated equivalent of the eight classes of un-
consolidated rocks.
Name of unconsolidated rock Name of consolidated equivalent
Boulders Boulder conglomerate
Coarse gravel Coarse conglomerate
Medium gravel Medium conglomerate
Fine gravel Fine conglomerate
Coarse sand Coarse sandstone
Medium sand Medium sandstone
Fine sand Fine sandstone
Clay Claystone
OnNDMLPwWh —
* A formation, group of formations, or part of a formation that is
water bearing.
21
TABLE 1
CLASSIFICATION OF UNCONSOLIDATED MATERIALS
Name to be
Applied in
Classification Grade Name Particle Dimensions** Logging
(mm) (in.) Water Wells
Very large boulders 2048 to 4096 80 to 160
Large boulders 1024 to 2048 40 to 80
Medium boulders 512 to 1024 20 te 40
Boulders
Small boulders 256 to 512 10 to 20
Large cobbles 128 to 256 5 to 10
GRAVEL Small cobbles 64 to 128 5 to 5 Coarse
Very coarse pebbles 32 to 64 «3 to 2.5 Gravel
Coarse pebbles to 32 .6 to 1. Medium
Medium pebbles to 16 eye Gravel
Fine pebbles to oe OO. Fine
Very fine pebbles to .08 to . Gravel
Very coarse sand to Coarse
Coarse sand -5 to Sand
Medium sand 25 to .5 Medium sand
Fine sand .125 to .25
Very fine sand .062 to .125 Fine sand
Coarse silt .031 to .062
Medium silt .016 to .031
Fine silt .008 to .016
Very fine silt -004 to .008
CLAY AND Coarse clay .002 to .004
SILT
Medium clay .001 to .002
Fine clay .0005 to .001
Very fine clay 00024 to .0005
*#® American Geological Institute Data Sieet No. 7
Fig. 5 NOMENCLATURE OF UNCONSOLIDATED ROCKS
5 inches or greater
in diameter
lain nies isha
80ULDERS COARSE SAND
e Ofte e, Ge Ff Fo)
TS ie
’ 3 °
: es Speen te "05 Oy
2 1/2 to 5 inches 00° 0 9998 4900 0 a0,
: x pee 50.9%0q 20% 8,8
in diameter M100 g' FO eared
=
nn 6? %
20
COARSE GRAVEL
FINE SAND
Coarsest particles
barely visibie
re
FINE GRAVEL
Sedimentary rocks and volcanic rocks are sometimes interbedded with
strata of volcanic ejecta. Some of these strata have been deposited
by water and others by direct air fall. The terms “pumice” and “cin-
ders" should be used to describe these materials.
Pumice A very light, excessively cellular volcanic glass. Its
color is generally light gray or white and is often so
light that it will float on water.
Cinders Uncemented glassy and vesicular ejecta from a volcanic
cone. Generally black or red in color. In logging a
well penetrating into strata of cinders, the cinders
should be also described by color and degrees of coarse-
ness.
MISCELLANEOUS TERMS RELATED TO SEDIMENTARY ROCKS:
Caliche A hard lime deposit generally found in the soil zone
in arid regions. It is usually found in layers rang-
ing from a few inches to a few feet in thickness.
Chalk A soft, white to gray, fine-grained limestone. Often
incorrectly used on well logs to describe diatomite.
Diatomite A soft white to gray, fine-grained rock composed of
the siliceous shells of diatoms.
Dirt A term used by many well drillers’ to describe the soil
zone. The term "soil" with a descriptive adjective as
"gravelly soil" or "sandy soil" is recommended for use
on well logs.
A term applied by some well drillers to a soft sticky
clay. The term "soft sticky clay" is preferred for
use on well logs.
Hardpan A term that has been applied to many hard impermeable
rocks including glacial $i1]1, caliche, conglomerate,
claystone, and sandstone. The term should never be
used on a well log.
Wind deposited material composed chiefly of silt but
may contain subordinate amounts of very fine sand and
clay. Loess should generally be reported as clay on
a well log.
A term used by many well drillers to describe soft
clay or silt. The term "soft clay" is preferred for
use on well logs.
Quicksand A term often applied to "running" or "heaving" sand.
The terms "finesand, waterbearing" or medium sand,
waterbearing" is preferred for use on well logs.
A laminated claystone. As laminations are not generally
discernible in drill cuttings, the term "claystone" is
preferred for use on well logs.
A metamorphic rock possessing a very well developed platy
cleavage. The term has been used by many well drillers
to describe a "hard claystone". It is recommended that
this term not be used to describe sedimentary rocks but
restricted to true slates.
POROSITY AND PERMEABILITY
Porosity is essentially the capacity of a rock or sediment to contain
water. It can be measured as the total volume of a material that jis
void space. Permeability is the capacity of a rock or sediment to
transmit water. Permeability is measurable as the quantity of water
flowing through a given cross-sectional area per unit time. Permea-
bility is directly proportional to grain size. Thus clay, which has
a high porosity, has a very low permeability because it is fine
grained.
The following figures indicate the porostiy of common soils and rocks:
Sand and gravels of fairly uniform size 35% - 40%
and moderately compacted
Well-graded and compacted sands and 25% - 30%
gravels
Sandstone 4% - 30%
Chalk 14% - 45%
Granite, schist, and gneiss 0.02% - 2%
Slate and shale 0.5 % - 8%
Limestone 0.5 % - 17%
Clay 44% - 47%
Topsoils 37% - 65%
Silts may be as high as 80% porosity In general, soils with fine,
separate particles, such as clay, to,soil, and silt, have a very high
porosity. In other words, they have a big volume in which water can
be stored.
EVALUATION OF SOURCES
THE QUALITY OF WATER
Absolutely pure water is never found in nature. The impurities in water
vary from dissolved gases and chemici] compounds to suspended matter
such as disease organisms and dirt. thile some of these impurities
can be seen by the naked eye and othe«s can be detected by taste or odor,
most can be detected only by laborato y test.
25
a
Water takes on various characteristics and properties as it passes
over and through the earth. These characteristics and properties
vary, and are dependent on the materials encountered. They may be
classified according to means of detection as physical (detected by
one or more of the five senses) and chemical (detected by chemical
analysis). The most important physical characteristics are turbidity,
color, odor, taste and temperature. The most important chemical char-
acteristics are acidity, alkalinity, hardness, and corrosiveness.
Sometimes these two types of characteristics overlap; for example, iron
in water is a dissolved mineral detectable by chemical analysis, yet
its color and taste are also physical. This section discusses these
characteristics and their causes.
BACTERIOLOGICAL QUALITY
The selection of a source of supply may be restricted because of eco-
nomic or technical limitations involved in the use of normal water-
treatment processes for making the water from this source safe for
human consumption.
The effectiveness of a water-treatment process can not be established
in specific, quantitative values. For instance, the bacteriological
quality of fiitered, chiorinated water is dependent upon the bacteria:
content of the raw water; its chlorine dexand; the coagulating, settling
and filtering characteristics of the treati.ent plant; the degree of
uniformity of the raw water; and, not least, the integrity and ability
of the treatment plant operator. Furthermore, the public health siqni-
ficance of the degree of bacterial pollution of raw water, and hence
of any bacteria remaining in the treated water produced, depends upon
she nrobable source of contaminavion of the raw water with coliform
organism=. which serve as an indicator of pollution. These organisms
may have originated targely from surface drainage, a situation likely
to be most noticeapie when manured fields are found within the watershed
involved. On the other hand, sewage pollution may be the chief source
of such oraanisms, in which case the indidence of intestinal diseases
among the population contributing the sewage would have ammarked impact
on the water. In this case the prrbable ratio between the numbers of
pathogenic organisms and of colifrrm Sacteria in the polluted water
will be considerably increased. su’ conditions are often encountered
in rural as well as semi-urban ar> where intestinal diseases constitute
a serious public health problem; 4 treatment of the sewage is not prac-
ticable, and effective water-trea rent is beyond the economic and tech-
nical resources available.
For these reasons, any bacteriological standards of quality adopted
for drinking-water on a country-wide basis generally appear to be
too rigid for large areas where, because of economic and social con-
ditions, they are most difficult to apply and enforce. However, it
must be reckoned that the adoption under these circumstances of more
lenient standards, because they appear to be more realistic, only
confuse the issue by lowering the goal of safety and potability without
providing a meaningful substitute. Instead, it is preferable to keep
the public health objectives of the water supply constantly in mind,
but to appradse local situations and review pertinent information in
the light of qualified professional judgement. In many cases, there-
fore, it is best for you to rule out the use of many surface waters
which might appear to be suitable and convenient sources of potable
water supply, and to throw considerable emphasis upon the use of
ground waters whenever feasible.
The above statement should not be interpreted to mean that surface
waters, because of bacteriological considerations, are unsuitable
sources of supply for rural communities. This would be far from the
truth. In fact, the use of surface waters often makes it possible to
provide consumers with ample quantities of water in their own homes,
thus fulfilling most of the major health objectives of the systems.
In some instances this is achieved by passing surface water through a
simple and economical treatment plant. In most rural situations such
a system may be considered as a step in the right direction, and is
to be preferred to the appalling conditions under which the villagers
are forced to carry, or even to purchase, small amounts of raw and
polluted water. As time goes on, public pressure, technological ad-
vances, and the development through training of local skills, will
graduaily bring about the improvement of plant efficiency, operation
and technical supervision to a point where the enforcement of existing
standards of water quality may be possible.
It is necessary and desirable to establish some form of control over
rural water-supplies. However, in most countries of the world, routine
bacteriological control, which is obligatory in urban communities,
would be unrealistic under rural situations, as indicated by the above
discussion. In the latter, the attention of the local health admin-
istration should be concentrated primarily -on those major elements of
location and design of the supplies which will afford natural protec-
tion later against outside contamination, and on routine sanitary in-
spections by qualified sanitarians, to educate the rural population
in the application and enforcement of rural sanitation regulations.
Periodically tests for physical, chemical, and bacteriological quality
should be made for the purpose of detecting major health hazards.
Bacteriological Standards for Drinking Water Recommended by the
WHO Study Group
Some public drinking-water supplies are chlorinated or otherwise
disinfected before being distributed; others are not. Effective
chlorination yields a water which is virtually free from coliform
organisms i.e. these organisms are absent in 100-m! portions;
if communal supplies which are distributed without treatment or
disinfection cannot be maintained to the bacteriological standard
established for treated and disinfected water, steps should be
taken to institute chlorination or disinfection, or other treat-
ment, of these supplies.
A standard demanding that coliform organisms be absent from each
100-m] sample of water entering the distribution system--whether
the water be disinfected or naturally pure--and from at least 90%
of the samples taken from the distribution system can be applied
in many parts of the world. Although there is no doubt that this
is a standard that should be aimed at everywhere, there are many
areas in which the attainment of such a standard is not economi-
cally or technically practicable.
In these circumstances there would appear to be economic and
technical reasons for establishing different bacteriological
standards for public water-supplies which are treated or disin-
fected and for those which are not treated. The following bac-
teriological standards are recommended for treated and untreated
supplies of present use throughout the world, with the hope that
improvements in economic and technical resources will permit stric-
ter standards to be adopted in the future.
The standards described below are based on the assumption that
frequent samples of water will be taken...For each individual
sample, coliform density is estimated in terms of the "most
probable number (MPN)" in 100-m] of water, or "MPN" index...
The use of the MPN index is recommended as the basis of quanti-
tative estimation of coliform density after full recognition of
its limitations. However, the value of the index is sufficiently
enhanced by the use of data from a series of samples to warrant
its use in the recommended standards.
Treated Water
In 90% of the samples examined throughout any year, coliform
bacteria shall not be detected or the MPN index of coliform micro-
organisms shall be less than 1.0. None of the samples shall have
an MPN index of coliform bacteria in excess of 10.
An MPN index of 8-10 should not occur in consecutive samples.
With the examination of five 10-m] portions of a sample this
would preclude three of the five 10-m] portions (an MPN index of
9.2) being positive in consecutive samples.
In any instance in which two consectuive samples show an MPN
index of coliform bacteria in excess of 8, an additional sample
or samples from the same sampling point should be examined with-
out delay. This is the minimum action that should be taken.
It may' also be desirable to examine samples from several points
in the distribution system and to supplement these with samples
collected from sources, reservoirs, pumping stations and treat-
ment points. In addition, the operation of all treatment pro-
cesses should be investigated immediately.
Untreated Water
In 90% of the samples examined throughout any year, the MPN index
of coliform micro-organisms should be less than 10. None of the
samples should show an MPN index greater than 20.
An MPN index of 15 or more should not be permitted in consecutive
samples. With the examination of five 10-ml portions of a sample,
this would preclude four of the five 10-m] portions (an MPN index
of 16) being positive in consecutive samples. If the MPN index
is consistently 20 or greater, application of treatment to the
water-supply should be considered.
In any instance in which two consecutive samples show an MPN index
of coliform organisms greater than 10, an additional sample or
samples from the same sampling point should be examined immedi-
ately. It may also be desirable to examine samples from several
points in the distribution system and to supplement these with
samples collected from sources, reservoirs and pumping stations.
When accurate and complete data concerning the sanitary conditions
at the sources of an untreated water-supply, covering al] possible
points of pollution, are available and indicate that indices high-
er than the established maximum may bear little relation to poten-
tial health hazards, the local health and water-supply authorities
should be responsible for ruling that such higher indices do not
constitute need for treatment of the water.
CHEMICAL AND PHYSICAL QUALITY
Water of good chemical and physical quality is necessary from the
points of view of its acceptability by the people, the protection of
the health of the consumer, and the conservation of the water system.
Anyone who has drank water from different sources encountered situa-
tions in which offending chemical substances have made a water source
unacceptable even though its bacteriological quality was excellent.
Palatability of water is a term which describes the characteristic of
being pleasing to the sense of taste. Drinking water should be free
from color, turbidity, taste, and odor, and. should be cool and aerated.
At least four human perceptions can be used in judging these qualities.
They are the senses of sight (color and turbidity), taste, smell] (odor),
and touch (temperature). However, palatable water is not always safe
to drink or potable.
Turbidity and color are important in rural water-supplies. Depending
upon the character of the watershed, turbidity may vary considerably
from one season to another because of rainfall. A sudden increase in
turbidity may do serious damage, or at least stop the operation, of
small water-treatment plants if adequate precautions are not taken in
advance in order to allow for rejection of the incoming supplies at
such times. Water from slow-moving streams and smal] lakes is likely
to be colored, at least during certain seasons of the year. Both tur-
bidity and color will cause discoloration of clothes and may be respon-
sible for rejection of the supply if removal by simple and economical]
processes cannot be achieved.
CORROSION AND SCALE
Hydrogen sulfide, dissolved oxygen, and carbon dioxide in water cause
acidity and are responsible for corrosion of iron pipes. Hydrogen
sulfide, which is sometimes found in deep-well water, is a product of
decomposition of organic matter. It attacks cement and concrete and
29
destroys storage tanks built of these materials. Dissolved oxygen
combines with ferrous iron, which is sometimes found in solution in
well water, and produces ferric hydroxide, which is insoluble and
gives the water a rusty color. It may also cause serious corrosion
of distribution pipes and house plumbing pipes.
Perhaps the most important and troublesome of the three products
mentioned here is carbon dioxide, which is often found in wel] water
and in surface water drawn from heavily wooded watersheds or from
the lower layers of deep ponds. Carbon dioxide in water is respon-
sible for heavy and rapid corrosion of unprotected pipes, thus crea-
ting increasing difficulties with maintenance and operation of a water
system. Various materials, mostly bituminous compounds and cement
are used by manufacturers for lining the interior surfaces of pipes
against corrosion. These materials are also used to protect outside
pipe surfaces against corrosion caused by the contact of pipes with
certain soils and, under certain circumstances, by electrolysis.
Natural water containing carbon dioxide wil! dissolve carbonates from
rocks in the ground, thus producing soluble bicarbonates. Depending
upon the relationships between the bicarbonate alkalinity and the pl
of the water on the one hand, and between the free carbon dioxide and
the alkalinity on the other, the water will either be corrosive or,
on the contrary, will deposit a film of carbonate on the inner sur-
face of pipes. This film may somtimes develop sufficiently to become
a thick scale which obstructs small distribution and service pipes,
water meters, etc. The prevention of corrosion and scale rests upon
the chemical control and maintenance of the proper equilibrium between
the three factors mentioned, j.e., by reducing the content of carbon
dioxide or increasing the alkalinity as determined by special tests.
Except in rare instances, this type of chemical control is beyond the
technical resources of smal] rural water-supply systems and, therefore,
will not be discussed here in greater detail.
TURBIDITY
Turbidity is a muddy or unclear condition of water, caused by particles
of sand, silt, clay, or organic matter being held in suspension. The
faster water flows, the more material it picks up and the larger the
size of the pieces carried along. As water shows down, the larger part-
icles settle out. Clay and silt remain suspended in water longest,
because of their particle size and specific gravities.
COLOR
Color in water is due to the presence of colored substances in solution
such as vegetable matter dissolved from roots and leaves, and to humus
and iron and manganese salts. True color is due to substances in true
solution; apparent color includes true color and also that due to sub-
stances in suspension. Water taken from swamps, weedy lakes, and
streams containing vegetation is most likely to be colored. Color may
also be caused by industrial wastes and turbidity. The latter is re-
sponsible for an apparent color, rather than the true color, and is
caused by materials of vegetable origin. Color as such is harmless,
but objectionable due to its appearance and to the taste and odors
sometimes associated with it.
ODORS AND TASTE
Taste and odors found in water are most commonly sautced by alga (min-
ute water plants), decomposing organic matter, dissolved gases, or
industrial waste. Mineral substances may also be a cause. Potability
is not normally affected by the presence of odors and tastes. On the
other hand, palatability is frequently affected, particularly when a
substance such as bone or fish oi] is present. Water containing one
of these substances in noticeable quantities is unpalatable. Tastes
and odors which make water unpalatable must be removed. Use of free
available chlorine and activated carbon will do much to prevent odor-
ous combinations of chlorine with organic impurities in water.
TEMPERATURE
Warm water tastes flat. Lowering the temperature of water suppresses
odors and tastes and, therefore, increases its palatability. In the
sumer the temperature of deep lakes and reservoirs decreases sharply
from top to bottom. By shifting the depth of intake, it may be pos-
sible to draw relatively cool water even during hot weather. Water
should be drawn from the lower depths when possible. Coo) water is
more viscous than warm water and thus is more difficult to coagulate
and effectively chlorinate than warm water due to slower reactions.
Water treatment times should be increased when water temperatures are
less than 45°F,
ACIDITY AND ALKALINITY
Some of the physical impurities mentioned cause water to behave as
either an acid or as a base. The degree of acid behavior is called
acidity. The deqree of basic behavior is called alkalinity. Since
either condition has an important bearing on water treatment, the
degree of acidity or of alkalinity must be determined.
The pH value is a measure of the acidic or alkaline nature of the
water. The pi value ranges from 0 - 14. A value of 7 is neutral.
A high pl! value indicates a very strong alkaline solution.
The pH influences the corrosiveness of the water, the amount of chem-
ical dosages necessary for proper disinfection, and the ability of
an analyst to detect contaminants.
HARDNESS AND OTHER CHARACTERISTICS DUE TO DISSOLVED MINERALS
Hardness js caused by the soluble salts of calcium, magnesium, iron,
manganese, sodium, sulfates, chlorides, and nitrates. The degree of
hardness depends on the type and on the amount of impurities present
in the water. Hardness also depends on the amount of carbon dioxide
influences the solubility of the impurities that cause hardness.
-2l-
The hardness caused by carbonates and bicarbonates is called carbonate
hardness. The hardness caused by all others (chlorides, sulfates,
nitrates) is called non-carbonate hardness. Alkalinity is usually
equivalent to the carbonate hardness. Sodium, however, also causes
alkalinity. In natural waters, sodium is not normally present in
appreciable amounts. Therefore, in natural waters, the alkalinity
is equal to the carbonate hardness. After a water has been softened,
however, a iarge amount of sodium remains in the treated water. In
softened water, the total alkalinity is the sum of the cardonate alka-
linity plus the sodium alkalinity.
Hardness is undesirable in that it consumes soap, makes water less
satisfactory for cooking, and produces scale in boilers and distil-
lation units.
The following minerals cause hardness in ground and surface waters:
Calcium carbonate. Alkaline and only slightly soluble;
causes carbonate hardness and alkalinity in water.
Calcium bicarbonate. Contributes to the alkalinity and
carbonate hardness of water. Calcium bicarbonate when
heated produces carbon dioxide and calcium carbonate.
This calcium carbonate precipitates as scale in boilers
and distillation units.
Calcium sulfate or gypsum. Causes noncarbonate hardness
in water. Being more soluble in cold water than in hot, it
separates from the water in boilers and forms scale on the
boiler tubes.
Calcium chloride. Causes noncarbonate hardness in water.
In steam boilers and distillation units, the presence of
calcium chloride can cause chemical reactions which result
in pitting of the boiler tubes.
FACTORS INFLUENCING THE QUALITY OF WATER
As water goes through its hydrologic cycle, it gathers numerous impurities.
Dust, smoke, and gases fill the air and tend to contaminate rain, snow,
hail, and sleet. As runoff, water picks up silt, chemicals, and disease
organisms. As it enters the earth through seepage and infiltration, some
of the suspended impurities may be filtered out, but at the same time,
other minerals and chemicals are dissolved and carried along. It is now
ground water in an underground deposit and, although it may now become
less contaminated or polluted, it is not necessarily pure, and may contain
disease organisms as well as harmful chemicals.
In addition to the impurities in water resulting from infiltration, many
are contributed by an industrialized society. Garbage, sewage, industrial
waste, insect sprays, and chemical, biological, and radiological agents
are examples of these.
Impurities in water are either suspended or dissolved. The suspended
impurities are usually more dangerous to health. They include mineral
matter, disease organisms, silt, bacteria, and algae, and must be des-
troyed or removed from water that is to be consumed.
1) The main factors influencing the quality of a given water supply
source are:
A) Nature of the surface geology; character of soils and rocks.
B) Character of vegetation; forests; cultivated and irrigated
lands, including salinity, effect on irrigation water, etc.
Methods of sewage disposal whether by diversion from watershed
or by treatment.
Character and efficiency of sewage-treatment works on watershed.
Proximity of sources of faecal pollution to intake of water
supply.
TURBIDITY TEST
The turbidity test is used to show the amount of suspended matter pres-
ent in raw water, and also to determine the amount removed from treated
water. The test may be made with the white porcelain cup with its
black enameled dot, or by employing the turbidimeter and standard tur-
bidity solution. Rapid approximate readings only can be made by usina
the cup.
Turbidity Determination by Use of Measuring Cup:
The measuring cup can be used to determine whether raw water has
more or less than 100 turbidity units. If the black spot cannot
be seen when the cup is filled to the top with the water sample,
the turbidity is 100 units or over. The turbidity is less than
100 units if the outline of the black spot is visible.
DOT CLEAR DOT HAZY DOT OBSCURED
a ew oe BETWEEN 5 ppm AND 100 ppm MORE THAN 100 ppm
Fig. 6 Turbidity Test
Waters having low turbidities, such as effluent from a purifica-
tion unit, may be checked by adding about 1/2 inch of water to
the cup and looking at the black spot, it appears as black as it
was originally, the turbidity is less than 5 units. Turbidities
over 5 units produce a graying or milky hue in the black spot.
THE QUANTITY OF WATER
Surface water originates mostly from rainfall and is a mixture of surface
run-off and ground water. It includes large rivers, ponds and lakes, and
the small upland streams which may originate from springs and collect the
run-off from the watersheds. The quantity of run-off depends upon a large
number of factors, the most important of which are the amount and intensity
of rainfall, the.climate and vegetation and, alsc, the geological, geog-
raphical, and topographical features of the area under consideration. It
varies widely, from about 20% in arid and sandy areas where the rainfall
is heavy. Of the remaining portion of the rainfall, some of the water
percolates into the ground, and the rest is lost by evaporation, trans-
piration and absorption.
FACTORS INFLUENCING THE QUANTITY OF WATER
A) Total annual precipitation.
B) Seasonal distribution of precipitation. Both the total annual
precipitation and the seasonal distribution of precipitation
are best determined by past record.
C) Soil porosity and permeability.
D) Annual and monthly evaporation and transpiration.
One of the first steps in the selection of a suitable water supply
source is determining the demand which will be placed on it. The
essential elements of water demand include the average daily water
consumption and the peak rate of demand. The average daily water
consumption must be estimated:
1. To determine the ability of the water source to meet con-
tinuing demands over critical periods, when surface flows
are low, and ground-water tables are at minimum elevations.
For purposes of estimating quantities of stored water which
would sustain demands during these critical periods.
The peak demand rates must be estimated in order to determine plumbing
and pipe sizing, pressure losses, and storage requirements necessary
to supply sufficient water during periods of peak water demand.
-24-
TYPES OF SOURCES
SURFACE WATERS
Surface water sources are lakes and ponds, rivers, streams, and control-
led catchments (cisterns).
Lakes and Ponds
A lake or pond is any standing body of inland water.
Quantity: Advantageous in that it is usually able to store
water in wet periods for use in dry periods.
Quality: Generally poor. Normally turbidity and bacteria are
the major pollutants. Use only when ground water sources
and controlled catchments are not available or are insuf-
ficient or inadequate.
Development requirements: The ideal situation is that the water-
shed permits water of the highest quality to enter the pond.
To approach this goal, the watershed should be clean, free
from septic tanks, barns, privies, etc., protected against
erosion and drainage from livestock areas, and livestock
should be excluded (fencing if necessary).
Treatment requirements: No lake or pond water can be considered
safe until it has been disinfected. Generally it is also
necessary to remove turbidity.
Treatment processes:
1) Sedimentation plant - (w/o alum for coagulation) allows
large particles of turbidity to settle out.
2) Filtration to remove turbidity and reduce bacterial content.
3) Disinfection
Warning: Lake and pond waters usually require extensive treatment
and a floating intake structure. In many cases the filtration
unit becomes clogged and must be cleaned. It is advisable to look
elsewhere for a source of water.
Rivers and Streams
General: A stream or river is a body of running water on the sur-
face of the earth, from higher to lower ground.
Quantity: Yield controlled by rate of minimum flow per day and
year. Streams generally exhibit marked seasonal variation in
flow.
35
Quality:. Generally poor. Chemical nature partially dependent
on bedrock. Physical and bacteriological quality highly
variable. Easily contaminated. Impossible to exert sani-
tary control over watershed.
Development requirements: Requires a submerged intake structure
and in the case of small streams requires the construction
of small diversion dams.
Treatment requirements: Same as lakes and ponds. Likely to be
more turbid and have a qreater quantity of chemical pollu-
tants.
Treatment Processes: Same as the lakes and ponds.
Warning: Rivers and streams should be considered last as a poten-
tial source of water unless, of course, adequate treatment
facilities already exist.
Springs
General: The outflow of water that has previously run or per-
colated through the pores of rocks. Two types:
1. Gravity-around water flows over impervious stratum onto
qround surface.
Artesian-water rise to surface after confinement between
two impervious beds.
Quantity: (1) Yield of gravity springs fluctuates with rainfall
Characteristically have low discharge. (2) Artesian springs
tend to have a nearly constant yield.
Quality: Are subject to contamination near points of emergence.
Poor to good. Usually contain dissolved minerals (especially
calcium carbonate). Caution*- springs emerging from limestone
channels allow for very little natural filtration. May become
highly turbid and polluted after heavy rains. Careful inves-
tigation recommended.
Development requirements: Elimination of all sources of contami-
nation near point of emergence. If gravity type, further
development not recommended.
Requirements---(1) filtration-sometimes not necessary
(2) disinfection
Processes: (1) slow-sand filter (2) chlorination
* Gravity springs have the advantage in that they provide a
gravity type distribution system. A filtration and storage
unit can be constructed before point of emergence. Such a
development is not feasible unless the spring has a substan-
tial yield.
Catch Basins (Cisterns)
General: A sloping surface area for collection of rainfall run-
off leading to a covered tank (cistern). Roofs are tne most
common collection areas.
Quantity: Dependent on amount and variation of rainfall, evapora-
tion, infiltration, and replacement of the soil deficit. For
covered surfaces, losses are less than fifteen percent.
Quality: Wholly dependent on the character of the surface of the
area of collection.
Development requirements: Construction of a watertight, manholed
covered, tank with outlet.
Treatment requirements: Tank must be periodically disinfected.
With fenced catch areas of clay surface, filtration advisable
before intake. With roofs, cement or other hard surfaces
it is advisable to have some screen to catch leaves, etc.
Hard surfaces should be cleaned periodically.
Treatment processes: Disinfection is the only necessary treatment.
GROUND WATER
Ground water serves the great majority of people who live in rural areas
and have a water-supply system of one type or another. The reason is
that, among the various sources of supply, ground-water is by far the
most practical and safe in nature. Even in a highly industrialized
country such as the USA, municipal ground-water installations far out-
number surface-water supplies. It is very probable that, for a long
time to come, ground water will be the most important source of supply
for most rural communities of the world.
The advantages of ground water are:
1. It is likely to be free of pathogenic bacteria;
2. Generally, it may be used without further treatment;
3. In many instances it can be found in the close vicinity of
rural communities;
4. It is often most practical and economical to obtain and dis-
tribute;
5. The water-bearing stratum from which it is drawn usually pro-
vides a natural storage at the point of intake.
The disadvantages are:
1. Ground water is often high in mineral content;
2. It usually requires pumping.
In ground-water supply investigations and design, the engineer is
concerned with the following steps:
1. to find it in the required quantity and quality as near as possible
to the center of consumption, in order to reduce transport costs;
2. to extract it by means of a system which produces the quantity re-
quired, safeguards the quality, and, at the same time, involves the
least capital outlay;
to transport the water to the consumer in a way which requires the
least amount of operational and maintenance skill and cost.
1 = Areas where there are good possibilities of obtaining water from infiltration galleries, well-point
systems
2 = Ground water is outcropping at this point, so that a flowing spring is formed. At the foot of river
banks and hills other springs may possibly be found.
3 = Top of ground-water table
4 = Area of infiltration to supply formation B
A = Non-confined (non-artesian), water-bearing formation covered with top soil
B = Confined (artesian), water-bearing formation
C = Impervious rock, or hard-pan formation
Fig. 7 Geological Formations
Ground water is that portion of the atmospheric precipitation, mostly
rainfall, which has percolated into the earth to form underground de-
posits called aquifers (water-bearing formations) (See Fig. 8). These
can be tapped by various means, to be discussed later; and, in the
great majority of cases, they can be used without further treatment for
individual and community water-supplies in rural areas. Fig. shows
the occurrence and distribution of subsurface water.
-28-
Fig. 8 OCCURRENCE AND DISTRIBUTION OF SUB-SURFACE WATER
SOIL WATER
Limited to the soil and reached
by ruvts
PELLICULAR WATER
Adheres to roca surfaces
throughout sone of sera-
tion aad is not moved by
gravity but may be ab
stracted by evaporation
and transpyation
GRAVITY ORK \ADOSE
WATER
Moves downward by force Pe
of gruty throughout Oe, we . :
tone LACESS OVER PELLICUAR parte’
oe vtec Sechas er psteg tet
(ZONE OF AERATION)
SUSPENDED WATER
UNDERSATURATED ZONE
PERCHED WATER FSS
Occurs locally in the sone FSS
above an impervious bar-
| ner
VARIETILS OCCU KKING THROUGHOLT
ZONI: OF SUSPENDED WATER
5
cies,
Cal ee °°
CAPILLARY WATER ji atts Nowras = anid any , FRINGE: i
a ae a | ” naa
FREE WATER Ee Wa TER: (TABL, ABLES
Ovours below the water table {7
and is buunded by the first ef- ©
fective confining stratum
ZONE OF INTERCONNECTED OPENINGS
‘
rea a eo
CONFINED WATER
Oceurs Leneath ® confining -<-
e(ratum iS
FIXED GROUND WATER
Occurs in subeapillary openings,
not moved by gravity
GROUND WATER
SATURATED ZONE
(PHREATIC WATER)
CONNATE WATER
Water entrapped in the rocks
at the time of their formation
: 7 6. Chemically combined water
INTERNAL WATER b. Water treed in di connected Interstloes
¢. Water dissolved iv magus
INITIAL FLOW
WATER-TABLE ARTESIAN
BC = theoretical static level of confined water body
BC’ = pressure gradient; indicates actual static level in wells piercing the conduit
Reproduced from Tolman, C. F. (1937) Ground water, p. 35, by kind permission of McGraw-Hill Book Co.
Inc., New York
BEST COPY AVAILABLE
39
The great majority of wells for rural water-supplies take water from
the "free-water zone". (Figs. 9, 10). These will usually be jetted,
dug, driven, or bored wells. Infiltration galleries also take water
from this zone. Drilled wells often penetrate the confined water
aquifer. It is from this stratum that flowing wells are developed.
The aquifer must be supplied with an ample quantity of water if it is
to serve as a source. It is simply a reservoir and can be depleted in
the same manner as a surface reservoir if its supply is inferior to the
demand placed on ft. In rural areas this is very seldom a concern as
the aquifer will usually be replenished sufficiently to supply the rela-
tively small demands of rural communities. An element of greater sig-
nificance for the engineer searching for ground water pertains to the
characteristics of the soil formation of the aquifer, {.e., to the abil-
ity of the aquifer to give up water and, therefore, to serve as a re-
liable source of supply.
The quantity of water that can be extracted from an aquifer will depend
on (1) its porosity and permeability, and (2) the draw-down ¢., vhe
well. The porosity and the permeability, of a formation are 1‘1 ited
by nature; and while conditions may be altered somewhat in the immediate
vicinity of a well intake, the general nature of the aquifer is ¢ixed
and cannot be modified. The draw-down in a well, however, can be varied
within the limits of the thickness of the aquifer, the penetration of
the well into the aquifer, and the capacity of the pump used (Fig. 9,10).
Ground formations, however, have a certain tendency to hold the water
and to give up only a part of it. This characteristic of a soil for-
mation is called permeability; it is the quality of a formation which
controls the passage of water through it. From a knowledge of hydrau-
lics, it is obvious that water will pass through large openings more
easily than it does through small ones.
Clays and topsoils have high porosity (large volume of voids) but low
permeability (very small opening between particles), so that water
passes through them with great difficulty. Gravels and sands, on the
other hand, are permeable and therefore allow ground water to pass with
relative ease. This type of formation is also porous, as can be seen
above, so that it can store large quantities of water. These, then,
are the water-bearing formations most amenable to the development of
wells and most important to the engineer in searching for a rural com-
munity water-supply. Sandstone is both porous and pervious and there-
fore an excellent aquifer which can be tapped to produce large quanti-
ties of water, especially if it is confined as shown in Fig. 9 (for-
mation B) and Fig.10 . Where it is known, for example, that sandstone
underlies an area, and where no other readily available source is found,
a test hole into this stratum would be a good risk. Chalk formations
in the British Isles and in Haiti are known to produce reasonable
quantities of water.
BEST COPY AVAILABLE
30-
Fig. 9 SHALLOW WELL IN FREE-WATER ZONE
P
'
A
SZ Y
B
"Beara I:
i VU diddddddsddddddldddddddddéddddde
WHo 8746 ©
A = Ground surface G = Draw-down
B = Top layers of soil H = Depth of penetration of well
C = Water-bearing stratum into aquifer
D .. Impervious stratum 1 = Draw-down cone
E . Thickness of water-bearing J = Curve of maximum draw-down
stratum P = Pump
. Water table R = Radius of circle of influence
Fig. 10 WELL TAPPING CONFINED WATER
P
A a
Vf, ~
! Q
' R me 2
] Z
! G
oO Hy --------- ®,
+f
ees ee
onO 6246 6
A = Ground surface G = Draw-down
C = Water-bearing stratum / Draw-down cone
D = Impervious stratum P = Pump
E = Thickness of water-bearing Q = Depth of water in well
stratum R = Radius of circle of influence
F = Water table
41 BEST COPY AVA ABLE
St.
Except for unusual geological features or underground dams, it can be
said that, in any drainage basin, ground-water always flows towards
the principal streams (Fig. 7 ). While there are exceptions to this
rule, the best place to look for shallow ground-water is at the bot-
tom of draws and valleys. It is in this area that pockets of sand
and gravel may have been deposited. If these are close to the present
stream or in an old course, they will probably be well supplied. Under-
ground sampling by boring or jetting in these areas will usually be
profitable. In this way, samples of the underaround formation can be
taken and examined to determine the characteristics of the aquifer and
its ability to supply the quantity of water needed. Fortunately, a
great many small towns in rural, underdeveloped areas have been built
along natural watercourses, so that the possibility of finding avail-
able ground-water as a source of supply may be somewhat improved in
such areas.
DEVELOPMENT OF WATER SOURCES
BASIC CONSIDERATIONS
Development of a water source includes all work which increases the
quantity and improves the quality of the water, or makes it more readily
available for treatment and distribution. The development of surface
water sources and springs is considered in this section.
In developing a source, dams, floats, aalleries, and similar improvements
may be used to increase the quantity and quality of the water. Some
of the more common improvements are discussed in succeeding paraaraphs.
‘ Elaborate developments should be avoided; simplicity brings more rapid
results. A temporary water source should not be converted into a per-
manent one until the area has been reconnoitered for a source requiring
less development. All intake hoses or pipes should be equipped with an
intake strainer regardless of the clearness of the water source. Suc-
tion strainers should be protected from floating debris which may dam-
age, clog, or unnecessariiy pollute them. Proper anchorage of suction
lines and strainers prevents loss of prime, punctured or kinked lines,
and damage to strainer. Figures 11,12,13 and 14 depict several of the
common methods of suction inlet anchorage.
Water at the intake point should be as clear and deep as possible. The
strainer on the suction hose is placed at least 4 inches below the water
level. This precaution reduces the possibility of the strainer becoming
clogged with floating debris, or the prime being lost due to air getting
into the suction line.
SURFACE WATER SUPPLIES
Advantages. For normal field water supply, surface water is the
most accessible type of water source. This source also lends itself
readily to the purification equipment common to most engineer units.
Surface water is the most easily developed source of water. Vari-
ous methods of constructing intake points for inland surface water
sources are discussed below.
42
-32-
Rocks and Stakes. If the stream is not too swift and the water is
sufficiently deep, an expedient intake may be prepared by placing
the intake strainer on a rock. This will prevent clogging of the
strainer by the streambed and provide enough water overhead to pre-
vent the suction of air into the intake pipe. If the water scurce
is a small stream or shallow lake the intake pipe can be secured
to a post or pile as shown in Fig. }}.
Pits. When a stream is so shallow that the intake screen is not
covered by at least 4 inches of water, a pit should be dug and the
screen laid on a rock or board placed at the bottom of the pit.
Pits dug in streams with clay or silt bottoms should be lined with
ravel to prevent dirt from entering the purification equipment
(Fig. 12 . The screen is surrounded by gravel which prevents col-
lapse of the sides of the pit and also shields the screen from dam-
age by large floating objects. The qravel also acts as a coarse
strainer for the water. A similar method may be provided by en-
closing the intake screen in a bucket as shown in Fig. 13
Dams. The level of the water in small streams can be raised to
cover the intake strainer by building a dam as shown in Fia. 14
In swiftly flowing streams, a wing or baffle dam can be construc-
(Ft to 5 vena the intake screen without impoundina the water
Fig. 15
Floats. Floats made of logs, lumber, sealed cans, or empty fuel
drums can be used to support the intake strainer in deep water.
They are especially useful in large streams where the quality of
the water varies across its width or where the water is not deep
enough near the banks to cover the intake strainer. The intake
point can be covered by an adequate depth of water by anchoring
or stationing the float at the deep part of the stream. The in-
take hose should be secured to the top of the float, allowing
enough slack for movement of the float. If support lines are used
to secure the float to the banks, the position of the float can be
altered to correspond to changes in depth by manipulation of the
lines. The chief advantage of a float intake is the ease with
which the screen can be adjusted vertically. Fig. ic illustrates
two types of improvised floats.
Gallertes. Water from muddy streams can be improved in quality by
digging intake galleries along the bank. A trench is dug along the
bank deep enough so that water from the stream percolates into it
so it intercepts ground water flowing toward the stream. The trench
is filled with gravel to prevent the sides from collapsing. The in-
take strainer is placed in the qravel below the water line (Fig. 17 ).
The amount of work required to produce the gallery is justified by
a reduction in the amount of chemicals needed to coagulate the water,
the elimination of the necessity of frequently backwashing the filter
and the higher quality of water obtained.
Drive Points. Many times it is advantageous to utilize shallow ground
water sources or percolated waters adjacent to a turbid surface water.
Well points are issued in 2-inch diameter, 54-inch lengths. A drive
‘ ENS Proen erae aaa ve CES ay ar
Sica SS i
alain aa y
S————
— :
LOW WATER LEVEL: —q——POST OR PILE”
}
{
eee elt
PARTICULARLY SUITABLE FOR he MA MA |
INLET FROM SMALL STREAM OR LAKE
Fig. 11 Direct intake, with hose on bottom of water source
wo UN "3,
WATER LEVEL
" ANTARE fg OO eB Ne ee ee ee ee ee
*', SCREEN at ok ee: ae ;
Co te tN Nas > en ns °
ro We a Me mr ee 4 2: ale a * ss ig ae . .
rpc ft ‘oe ae iS.
i. pes a ,
FINE GRAVEL AND SANO
Fig. 12 Surface intake with hose buried in gravel-filled pit.
44
4s 7
-34-
TO UNIT—,_
WATER LEVEL
. . - are ik * Pt 8 res
ss
-~ . . . bd
lige gt i Pas ee
. : » Nie EP, «bp hae oe : ¥
: eg Vem ee Wag ee . ws © > Po , * . e . °
e eee ¢ \ . . a ae @ mais 3 *¢.
s+ &# . .- +" Fs <a , Pie, , . *
o ee : Pie ped he re to ke ° .
ee Ses on wanes ere Wd 5 * ‘ ,
e- « Ps . va Pas @ 85 . ae .
< a F oe is *« . .
= me ae eh: 2 *: ; : 3 .
* SVe aes seid oy iy 3 Z 7° ‘
FINE GRAVEL AND SAND - .o--s 0 ** > Ai
"wt “ne tie + -” INTAKE SCREEN
Fig, 13 Use of bucket on end of surface intake.
y
PICKETS
WIRcD
pes TOGETHER
‘ “y ap
of eal P ae
‘ . — nn of
SE MHOsE AND sar! Oe age
ee 5, SCREEN eo ow
’ Mi ° _
a a ; a /
B So ae iy — , 44 -
4 TO 1 SLOPE ~ a wie "CORRUGATED IRON
FRONT AND REAR___..- ? 5
4 ile Yor
. ~ My if
__\ wood or ~~ Y
ANGLE IRON :
PICKETS ~ oa
SAND3AGS FILLED WITH MUD~.
~ ie
~x ca
AQ
Fig. 14 Improvised dam for impounding sn) ses,
nie
BRANCHES
CROSS BRACES oa ar) yh ‘
- WAU ayie is
’ a) dary
wy fe ee
INTAKE SCREEN
Fig. 16 Float-type surface intake, with anchors.
Uff
Yi
WATER TABLE
WATER-BEARING SANDS
GALLERY FILLED WITH GRAVEL
Fig. 17 Gravel-filled gallery intake.
LEAD-OFF DITCH
SSSi%q CLEANOUT TRAP DOOR =}
ag al See Fr. oH
SLOPE FROM BOX. -"_L<* 2 OVERFLOW PIPE
UIT
~ SCREEN ©
OLA A LF dt
Fig. 18 Spring inlet.
47
cap is driven into the ground with a sledge. Successive sections
of pipe, each 5 feet long, are added and driven until the screen
is well within the water bearing media. Several well points may
be connected in parallel to supply sufficient water to the raw
water pump. In developing drive point sources, it must be remem-
bered that the practical limit of suction lift of the pumps issued
with field equipment is 22 to 25 feet at sea level. Suction lift
pumps can be used, therefore, only where the pumping level in the
well will be within the limit of suction lift, or 22 to 25 feet be-
low the position of the pump. At 5,000 feet above sea level, the
practical limit of suction lift is only 20 feet. It should be noted
that since a suction-lift pump must create a partial vacuum in the
suction line, it is necessary that the line be absolutely airtight
if the pump is to function properly.
SPRINGS
Springs yielding 20 oallons per minute or more of water can be used as
a source of field water supply if properly developed. Springs may be
developed by enlargina the outlet of the spring, and by reducing loss
by dammina and conducting water to storage. To reduce possible pcl-
lution, springs should be cleared of all debris, undergrowth, top soil,
loose rocks, and sand.
Water which flows from rocks under the force of gravity and collects in
depressions can be collected in boxes or basins of wood, tile, or con-
crete. The collecting box should be large enough to impound most of
the flow, and should be placed below the ground level so that only the
top is slightly above the surface. The box should be covered tightly
to prevent contamination and lessen evaporation. The inlet should be
designed to exclude surface drainage and prevent pollution. This re-
quires fencing off the area and providing proper drainage. Fig.
shows a spring inlet which has been protected in this manner. The
screen on the overflow pipe prevents the entrance of insects and smal]
animals. Another screen on the intake pipe prevents large suspended
particles from being ingested by the pump used to distribute the spring
water, thereby preventing mechanical failure or reducing it to a mini-
mum.
The flow of water from a sprina located on a steep slope of loose earth
can be obtained by the following two methods:
1. Constructing deep, narrow ditches leading from the spring to the
point of collection.
Constructing pipeline tunnels from the spring to the collecting
point. Pipe of large diameter is more suitable for this purpose.
The water from the tunnels can be trapped by constructing a dam
at the point of collection.
Digging is a more positive and more economical method of developing a
spring than blasting. In using explosives ir developing the yield
from springs you should exercise great caution. Blasting in unconsoli-
dated rocks may shift the sand or gravel in such a way as to divert the
spring to a different point.
48
SS warer TABLE
o* = SAND.FORMATION
Fig. 19 Typical dug well with suction pump.
SUCTION PUMP
(PITCHER PUMP)
= HO! & BACKFILLED
= WITH PUDDLED CLAY?
ere,
ts
_ +
69%
siatgpes aie: "a mts . Beinn
okt ae
WATER TABLE.
ee ee
’
*
WATER-BEARING SAND
= i ; A | ; : )
i. .
FINER SAND REMOVED
THROUGH SCREEN
WELLS
When ground and surface water supplies are inadequate or cannot be used,
ground water supplies are developed by constructing wells. Wells are
classified into five types, according to their method of construction.
These are dug, bored, driven, jetted and drilled wells. Each type of
well has its particular advantages, which may be ease of construction,
type of equipment required, storage capacity, ease of penetration into
certain types of formations, or ease of safeguarding against pollution.
THE BASIC REQUIREMENTS OF A WATER SUPPLY
The objectives of any water supply, big or small, are to provide the con-
sumers with safe and wholesome water in adequate amounts and to make that
water readily available to users.
SAFE AND WHOLESOME WATER
Safe and wholesome water is water that may be consumed without risk
from its chemical and bacteriological contents. Its color and odor
should be unobjectionable and it should be free of visible suspended
matter.
Much information concerning its sanitary quality may be obtained by
chemical examination of a water but it is impossible to say that a
water is free of sewage pollution by chemical analysis alone. Where
the presence of pollution is being investigated, bacteriological ex-
amination is essential. Water which the tests have shown to be safe
may be polluted after the samples have been taken and the only way of
ensuring the early detection of intermittent poliution is through fre-
quent routine bacteriological examinations. In rural] areas it is often
difficult enough to have one such examination done but to insist on
weekly repetitions would be quite unrealistic. The Bacillus coli which
normally lives in the bowels of warm-blooded animals and which is pre-
sent in human faeces in enormous numbers is used as the bacterial in-
dicator of pollution. Unfortunately there is no ready method of dif-
ferentiating B. coli of animal origin from those of human origin.
In view of the foregoing it is of the utmost importance that the supply
system be correctly located and constructed so as to provide natural
protection against outside contamination. A careful inspection of the
pertinent area must, therefore, be carried out, and it should be repeated
at regular intervals to ensure that this area is maintained in the neces-
sary sanitary state.
ADEQUATE QUANTITY
The average amount of water required daily by an individual is about
10 gallons for domestic purposes, i.e. drinking, cooking, bathing and
laundry. People can do with less for short periods when necessary, but
public health is best served by encouraging the use of water and dis-
couraging its waste. The provision of 25 or more gallons per person
per day does not include water needed for gardening purposes or for
animals.
ait.
The former usually affects only the bungalows and varies considerably
in amount. The standard daily allowances for animals are:--for horses
and cattle--10 gallons per capita: and for sheep, goats and pigs, 2 gal-
lons each. Hospitals require about 50 gallons per patient daily, and
schools need approximately 10 gallons daily for each child.
AVAILABILITY
From the purely public health view-point there is no question but that
the aim should be to supply safe and wholesome water in adequate quan-
tity to every family in its home. Generally, when individual families
are provided with taps in their own houses they look after the taps and
the wastage of water is minimal. On the other hand, where the distri-
bution of water is by public stand-pipes, the taps are generally left
running and many of them are repeatedly broken so that they cannot be
turned off. Unfortunately the capital cost of a waterpoint in each
house is often too great and it is then necessary to compromise be-
tween economic realities and the desired sanitary conditions.
Until they actually experience the benefits of safe water, villagers
rarely understand or appreciate its advantages and they will continue
to use their old polluted sources unless the new sanitary supply is
superior in some respects obvious to them, such as greater convenience
or greater reliability. They may bathe themselves and wash their clothes
at the new water-point but the general standard of household cleanliness
will vary inversely with the distance the water has to be carried. If
the new water-points are not as handy or as dependable as the old ones
the people will continue to use unprotected shallow wells near their
homes or persist in going to the river for polluted water. Such prac-
tices defeat the real object for which the new supply is being instal-
led, namely, to improve the public health. As many stand-pipes and
household connections as possible should, therefore, be supplied and
the layout of the whole pipe system should be such as to facilitate the
future provision of a tap in each house. The following are suggested
as minimum standards:--one stand-pipe should not serve much more than
40 people; and in the case of wells to which the people must go for their
water — should be at least one well for every 250 people Teeeiit-
mately).
SELECTION OF THE SOURCE OF SUPPLY
The choice of a source of supply for development depends on a number of factors,
chief among which are:--the quantity and auality of the water avaflable; the
possibilities of sanitary control of the catchment area; whether the water
can be supplied to the consumers hy gravity or has to be pumped; and the dis-
tance from the source to the houses. In order to obtain full information on
these points it is necessary to carry out a very careful preliminary survey.
SOURCE OF SUPPLY
The first sten in starting any water scheme is to determine what source
of supply are available. Frequently a good source is not difficult to
find but it is usually advisable to check all alternatives as sone may
be more economical and safer to develop. Sometimes suitable sources
are not obvious and a search should then be made in the valleys, alona
ue 52
-42-
the foot of the hills, where the vegetation is greener, and such places.
In this reconnaissance the inhabitants are generally very willing to
assist with their local knowledge.
If the search fails to reveal a satisfactory source an investigation of
the ground-water becomes necessary, and for this a knowledge of the lo-
cal geological formations is most helpful. Study of any existing wells
will provide some information about the layers it penetrates, and the
location, quantity and quality of the water. Unless a good deal is
already known about the aquifer it is expedient to sink test holes at
various likely spots. These holes may be made with a pipe, about 2
inches in diameter, tipped with a point, and driven into the ground by
a hammer, or a pipe sunk by an earth auger or by boring. This method
is generally successful provided the water is not-more than 30 feet
or so from the surface. If it is necessary to probe any deeper, it is
usually wise to obtain the services of an engineer possessing the ex-
perience and the equipment for this type of work. Deep well explora-
tion and construction are expensive and are not jobs for amateurs.
The next step is to determine the quantity of water available. The
rainfall figures may be obtained and the history of springs and exist-
ing wells may often be secured from the local residents. An estimate
of the capacity of the aquifer may be made by pumping a well and noting
the rate at which the well refills but the approximate yield in the
dry season must be determined as that is often a decisive factor.
THE SANITARY SURVEY
The sanitary conditions prevailing in the immediate areas of possible
sources should be thoroughly investigated. This is most important
because the methods of purification of water,under rural conditions,
are limited, and the process is too often neglected. Animal contamina-
tion of the water is very undesirable, and in some places may be danger-
ous, but the greatest hazard lies in pollution from human sources. It
may be possible to find a spring, or stream, coming from a safe catch-
ment area situated uphill] from human habitation, or it may be practi-
cable to render a source safe by moving potential origins of contamina-
tion or to protect the source by suitable intercepting drainage etc.
Though the water from a stream may be liable to pollution it is often
feasible to obtain wholesome water through wells and infiltration
channels sunk in sand and gravel layers near the stream. Wherever
possible the water should be examined chemically and bacteriological ly
and results considered in the light of the sanitary survey.
SOURCE AND TREATMENT
In the final selection of a source the following priorities should be
adopted.
First-priority Consideration
Water which requires no treatment to meet bacteriological, physical,
and chemical requirements and which can be delivered to the consumer
by a gravity system should be given first consideration. This
would usually be limited to springs and protectéd drainage areas.
Such a system requires no treatment and no pumping and, therefore,
o3
is ideal from the point of view of maintenance, which is thus
reduced to an absolute minimum.
Second-priority Consideration
Water which requires no treatment to meet bacteriological, physical,
and chemical requirements but which must be pumped to consumers,
would be the second choice. Well supplies would fall within this
category.
Pumping can be an economical and simple solution, but it can also
be an expensive and complicated one, according to local circum-
stances. It depends on the availability of qualified operators
and on the local cost of fuel. Such factors vary widely from
country to country and even from one rural area to another of a
given country; they vary also with the types and efficiency of
operation and maintenance programs developed for providing aid to
municipalities from centrally located headquarters.
Third-priority Consideration
Water which requires simple treatment before it can meet bacterio-
logical, physical, or chemical requirements but which can be deli-
vered to the consumer through a gravity system should be given
third-priority consideration. Simple treatment is considered to
be limited to: (1) storage which would provide plain sedimentation
and some reduction in bacteria, (2) chlorination without the use
of a mechanically operated chlorinator, (3) slow sand filtration;
or a combination of these.
For rural areas this is normally an inferior solution. It is usu-
ally more expensive than the above solutions and involves opera-
tional procedures which are most difficult to maintain in smal]
rural communities. In such places, when the chlorine stock runs
out, chlorination is abandoned in almost every instance; and, when
the slow sand filter becomes clogged, a by-pass is often considered
an easy arrangement. Such is the history of treatment measures
in most rural areas where routine technical assistance is not pro-
vided by a responsible agency.
Fourth-priority Consideration
Water which requires simple treatment, as mentioned above, and
which must be delivered to the consumers by pumping would obviously
be the most expensive choice to make,
DETERMINING THE RELATIVE COST OF A DEVELOPMENT
The easiest method of determining the relative cost of a development
is to:
Estimate the cost of the various components for a given design;
Calculate the time required for construction;
Determine the total labor cost from the price per hour;
Sum items A and C.
WATER SUPPLY SOURCES
LESSON NO. 1
LESSON OBJECTIVE: Describe the methods used to locate and record
existing water supply sources with respect to
the community to be served,
SUPPLEMENTAL MATERIALS
TOPIC INSTRUCTIONAL PROCEDURE RELATED READING
Topographic Hund out exercise on topographic contouring
Contouring and assist. students where necessary.
Topographic Discuss, the use of the compass and the Manuel of Field Seclogy
Mapping interpretation of topographic maps. p. 21-25.
Any basic laboratory
manual of Physical Geols
Demonstrate drawing a crude topographic map Manual of Field Geology
of a prominent. topographic feature, p. 36-50.
Outline what features are to be included and | A.F.M. TM 5-700
how they are to be represented in a topo- p. 615.
graphic sketch map.
Assign students to groups of five. Have each
group imap a quarter mile area. Each map
should include the following features:
1) man-made structures
2) livestock grazing areas
3) water supply sources
4.) disposal systems
Plane Table Demonstrate how to construct a more service-
Mapping able map, the plane table map.
LESSON OBJECTIVE:
WATER SUPrLY SOURCES
LESSON NO. 2
Demonstrate how to identify and evaluate various
water supply sources.
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS /
RELATED READING
Rock and Soil
Type
Physical and
Chemical
rollutants
Identification of
i‘hysical
Pollutants
Water Supply
Sources
Qutline the physical characteristics and
discuss the hydrological properties of the
basic rock and soil types.
Assist students in identifying the basic rock
and soil types.
Have euch student identify rock and soil
types from a series of circulating samples.
List the major chemical and physical poliu-
tants and discuss the nature of these
pollutants.
Demonstrate how to identify turbidity with
the measuring cup.
Assist students in identifying physical
pollutants from a suite of water samples.
Water semples: should reflect the various
pollutants: turbidity, coler, odor, taste
and temperature,
Outline the factors that influence the
quality and quantity of a given water supply
source,
List und discuss the characteristics of the
various water supply sources.
Demonstrate evaluating these sources in the
field,
Assign students to groups of five.
Assign each of these groups to 4 three mile
area.
Manual of Individual
Water Supply Systems
Pe 5-13.
Manual of Individual
Water Supply Systems
Pp . 13-20
WHO Monograph #42
Chapter 5.
WHO Monograph #42
Annex 4 (p. 271-275).
also p. 39-42.
BEST COPY AVAILABLE
WATER SUPPLY SOURCES
Lesson No. 2
(Continued )
each group evaluate each source in its
in terms of
location
quantity
quality as determined from any
physical pollutants present and
possible sources of contamination.
Assemble groups to have each growp report
on the feasibility of the water supply
sources in its area.
LESSON OBJECTIVE:
WATER SUPPLY SOURCES
LESSON NO. 3
Discuss developments that will improve the
quality and yield of the various water
Supply sources,
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS /
RELATED READING
‘ater Point
2velopments
Recall the need for water source developments
and describe several of these.
Demonstrate a method for determining the
relative cost of a source development from
a list of its components and an estimate of
the labor cost.
Supervise students in estimating the relative
of basic developments for
lakes and ponds
streams and rivers
cisterns
springs
Have each student describe and estimate the
relative cost of a development for each of
the four sources listed above.
WHO Monograph #42
Chapter 5.
Small Water Supplies
p. 14-25.
VTH #2, Pe 5-7, 11-13.
WHO Monograph #42
Annex 7, p. 297-310.
Diagrams or charts of
these types of
developments.
SECTION 2
WATER TREATMENT
OVERVIEW:
When the source of water supply is not entirely satisfactory treatment is
necessary to insure that the quality of the water meets certain require-
ments. The trainees are instructed in the basic requirements of water
treatment and receive detailed plans for the installation of two simple
yet effective treatment systems.
SECTION 2 WATER TREATMENT
QBJECTIVE: Determine which of the potential water supply
sources are the most economically feasible in
terms of any treatment process requirements.
Define minimal standards of concentration for
each pollutant.
Identify the nature and extent of pollution
for each water supply source.
Determine which type of treatment system
would most probably be necessary to reduce
the pollution level of each source to a
safe level.
Determine the cost of a treatment process or
processes for each source.
Select the most economical source(s) in terms
of capacity to serve appropriate numbers of
people, and treatment process requirements.
FUNCTIONAL SKILLS:
1. Describe the four methods used in treating
polluted water.
Identify the relative costs of different
types of treatment systems.
Know the effect various pollutants have on
different delivery systems.
Know what pollutants make water esthetically
objectionable.
Know what concentrations of chemical pollutants
and coliform bacteria constitute health hazards.
Identify the factors that influence the future
population trends of a given locale.
Recognize the relationship between number of
water system users and treatment process capac-
ities.
WATER TREATMENT (cont. )
TERMINAL PERFORMANCE TESTS:
:
Given the designs for various types of treat-
ment systems, calculate with reasonable accu-
racy the cost of each.
Given a list of pollutants, correctly list
after each one, if applicable:
a. in what circumstances it can contrihute
to the destruction of a delivery system.
in what concentration it makes water
esthetically objectionable.
in what concentration it constitutes a
health hazard.
WATER SUPPLY SOURCES AND TREATMENT
WATER TREATMENT
SELF PURIFICATION
Under favorable conditions, any polluted body of surface water--stream
or river, lake or pond--will rid itself of a certain amount of its pol-
lution by means of natura’ processes. This self-purification cannot de
depended upon to bring about complete purification, but it may well im-
prove the water quality sufficiently to ease the load on mechanical pu-
rification equipment.
STREAMS AND RIVERS
When sewage is discharged into water, a succession of changes in
water quality takes place. If the sewage is emptied into a lake
in which currents about the outfall are sluggish and shift their
direction with the wind, the changes occur in close proximity to
each other and, as a result, the pattern of changes is not crisply
distinguished. If, on the other hand, the water moves steadily
away from the outfall, as in a stream, the successive changes occur
in different river reaches and establish a profile of pollution
which is well defined. However, in most streams, this pattern is
by no means static. It shifts longitudinally along the stream and
is modified in intensity with changes in season and hydrography.
When a single large charge of sewage is poured into a clean stream,
the water becomes turbid, sunlight is shut out of the depths, and
green plants, which by photosynthesis remove carbon dioxide from the
water and release oxygen to it, die off. Depending on the stream
velocity, the water soon turns nearly black. Odorous sulfur compounds
are formed and solids settle to the bottom, forming a sludge. The
settled solids soon decompose, forming gases such as ammonia, carbon
dioxide, and methane or marsh gas. Scavenging organisms increase in
number until they match the food supply. The oxygen resources are
drawn upon heavlly and, when overloaded, become exhausted. Life in
such waters is confined to anaerobic bacteria (which exist when no
oxygen is available), larvae of certain insects such as mosquitoes,
and a few worms. There are no fish; turtles are generaliy the only
forms of higher life present. This condition is known as the zone
of degradation.
In a second zone, or zone of decomposition, more solids settle out, the
the water becomes somewhat clearer, and sunlight penetrates the sur-
face. Oxygen is absorbed from the atmosphere at the air-water inter-
face permitting the establishment of aerobic (oxyqen available) con-
ditions. The aerobic bacteria continue the conversion of organic
matter into nitrates, sulfates, and carbonates. These, together with
the carbon dioxide produced by decomposition as wel] as by bacteria
and plant life, are food sources. With sunlight now penetratina the
water, and with abundant food, algae beqin to flourish and form a
green scum over the surface.
In the third zone, or zone of recovery, algae become more numerous and
self-purification proceeds more rapidly. Green plants utilizing car-
bon dioxide and oxygen will liberate in the say time more oxygen than
is consumed, thus hastening the recovery of the stream. Simultaneously,
the fish that require little oxygen such as catfish and carp, are also
found. As the dissolved oxygen increases, more types of fish appear.
After recovery, in the zone of cleaner water, fish find the stream high-
ly favorable, as the algae support various aquatic insects and other
organisms on which fish feed. The water is clear or turbid according
to concentration of algae, and may have odor for the same reason.
Throughout the stages of recovery of self-purification, disease organisms
are greatly reduced in number because they lack proper food, and experi-
ence unfavorable temperatures and pli values of water. However, the
water is still dangerous since all disease organisms have not perished.
LAKES AND PONDS
Self-purification in lakes and ponds is brought about by the same pro-
cesses as in rivers and streams. However, currents are not as strong
and sedimentation plays a larger role. Large deposits of sludge, dead
algae, and other organic material build up on the bottom. In deep
lakes, self-purification is aided by seasonal “overturns.” This is
simply an exchange of bottom water for surface water which occurs in
the spring and fall, caused by the difference in the temperature of
the water at the surface and bottom of deep lakes.
BASIC STEPS IN TREATING WATER
COAGULATION
Turbidity in water consists of finely divided negatively charged col-
loidal materials which are kept in suspension by mutual repulsion.
Turbid water is difficult to clarify by filtration because these fine
particles can cause rapid plugging or even pass through a filter. The
agglomeration of these colloids into settleable or filtrable aggregates
through the action of certain chemicals is called coagulation. Iron
and aluminum salts are the most widely used coagulants in water treat-
ment plants.
SEDIMENTATION
Plain sedimentation is the natural settling of solids heavier than water
without the addition of chemical coagulants. Solids heavier than water
are held in suspension while in moving water, but gradually settle to
the bottom as the water velocity is reduced. The time required to
clarify water by sedimentation depends on the size of the suspended
particles and their specific gravity. Large and heavy particles settle
in a few minutes once the water has become still, whereas very smal]
particles such as clay and silt may remain in suspension for several
days.
Plain sedimentation is not ordinarily used as a separate step in water
treatment because the long period required for complete settling would
call for an 4mpractical number of settlino tanks. However, in emer-
gency situations, such as the necessity of taking water from a swift-
63
flowing stream which is heavily silt-laden after a rainstorm, special
sedimentation tanks may be set up as a first step. This initial re-
moval of turbidity reduces the load on the coagulation and filtration
steps of the water treatment process, and the frequency of filter back-
washing is reduced.
FILTRATION
Filtration consists of passing the water through some porous material
to remove the suspended impurities. Filtration is one of the oldest
and simplest procedures known to man for revoving suspended matter
from water and other fludis.
The simplest form of water filter is the sand filter. This filter
resembles a smal] reservoir, the bottom of which is a bed of filter
sand which in turn rests on a bed of wel!-graded agqregate with the
largest size aggregate being at the bottom. An underdrain system of
tile or brick is provided under the gravel to collect the water from
the filter area. The underdrain system consists of a header or main
conduit extending across the filter bed. Means are provided for reg-
ulating the flow of water out of the filter through this header and
also for controlling the rate of flow on to the filter. This allows
the filter to be operated at controlled rates which should not exceed
3.0 gallons per minute per square foot of filter area. An average
filter bed consists of about 12 to 20 inches of gravel and 20 to 40
inches of sand. The depth of water over the sand bed varies from 3
to 5 feet.
DISINFECTION
In addition to coagulation, sedimentation, and filtration, water must
undergo an additional treatment step: disinfection. This is neces-
sary because no combination of the other three steps can be relied
upon to remove all disease-producing organisms, the pH and temperature
of the water, the presence of interferring substances, and the degree
of protection afforded organisms from the disinfecting solution by
materials in which they are imbedded. Therefore, various concentra-
tions of disinfectant are required depending upon the local environ-
mental conditions and the amount of particle removal effected.
Chlorine is the most commonly used chemical for disinfection of water.
It is employed in field water supply in the form of calcium hypochlor-
ite, a standard item in the supply system (commercially known as HTH
powder). When the calcium hypochlorite is dissolved, the chlorine
goes into solution and a calcium carbonate sludge settles out. The
chlorine is present in the solution as hypochlorous acid or hypochlor-
ite ion depending on the pil, both of which are powerful oxidizing
substances. The chlorine available in either of these two forms
rapidly oxidizes the organic and inorqanic matter including the bac-
teria in the water. Jn this reaction the chlorine is converted to
chloride and is no lonaer available as a disinfectant. The organic
matter as well as such material as iron and manganese consume the
chlorine. The use of chlorine makes it possible to introduce an ac-
curately measured dosage to insure the destruction of disease-produc-
ing organisms as well as provide a readily measured residual to safe-
guard against recontamination. during further handling.
64
-54-
Chlorine Dosage
Dosage is the amount of chlorine added to water to satisfy the
chlorine demand as well as to provide a residual after a speci-
fied time. The amount required to disinfect water varies with
the organic content and pH value of the water, the temperature,
the time of contact, and the chlorine residual required, The
dosage is usually stated in terms of parts per million (ppm) or
milligrams per liter (mg/l). In water supply terminology, ppm
means the same thing as milliarams per liter or "“mg/1".
Chlorine Demand
The chlorine demand of water is the difference between the quantity
of chlorine applied in water treatment and the total available re-
sidual chlorine present at the end of a specified contact period.
The chlorine demand is dependent upon the nature and the quantity
of chlorine-consuming agents present and the pli value and tempera-
ture of the water (high pH and low temperatures retard disinfection
by chlorination). For comparative purposes, it is imperative that
all test conditions be stated. The smallest amount of residual
chlorine considered to be significant is 0.1 ppm. The relationship
of the demand to the length of che contact period is discussed be-
low. Some of the chlorine--consuming agents in the water are non-
pathogenic (non-disease causing organisms) but this bears no re-
lationship to the fact that they contribute to the total chlorine
demand of the water.
Residual Chlorine
As indicated above, residual chlorine is the amount of unreacted
chlorine remaining at a specified time after the chlorine compound
is added. Chlorine in aqueous solution is highly unstable. It
may change quantitatively and qualitatively under numerous condi-
tions, including the presence of other elements or compounds. The
total residual chlorine in the water can be chemically divided into
the following types:
1. Totalavailable_residual chlorine. This is the sum of the
free available chlorine and the combined available chlorine.
2. Free available chlorine. Refers to hypochlorous acid and
hypochlorite ion present in the water. These are the most
effective disinfection forms of chlorine. The free available
chlorine is a rapid-acting type, important because it can be
relied upon to destroy bacteria relatively quickly, and thus
is active during the period inmediately following chlorination.
The relative amount of each present in the water is dependent
upon the pil value of the water. It is important to remember
that when the pl! is raised-the quantity of free available
chlorine required to kill the same number of micro-organisms
increases. With decreasing temperature the same situation of
increasing dosane to maintain the same kill is encountered.
If the contact time is varied, then the dosage applied must
also be changed. For example, to shorten the contact time
the dosaqe would have to be increased.
65
Combined available chlorine. This results from the presence
of ammonia or organic nitrogen that will react to form simple
chloramines. Thus the term "combined available chlorine"
arises from the fact that the chlorine has combined with an-
other substance. Chloramines are a slower acting and less
active form of disinfectant. Therefore, a much higher concen-
tration than that of free available chlorine is needed to oro-
duce the same germ destroying effect. The specific chlora-
mines present are also a function of pH.
Disinfecting Time
Chlorine demand in most water is likely to be largely satisfied
10 minutes after chlorine is added. After the first 10 minutes
of chlorination, disinfection continues but at a diminishing rate.
A standard period of 30 minutes contact time is used to assure
that highly resistant or high disease-producing organisms have
been applied. Given a sufficiently large chlorine content, and if
certain other conditions are met, even such special water purifi-
cation problems as the presence of amoebic cysts or schistosomes
will be solved with.the 30-minute contact period.
DISINFECTION REQUIREMENTS FOR ENGINEER OPERATED FIELD WATER TREATMENT
EQUIPMENT
As has been previously discussed, the efficiency of the chemical dis-
infection process is dependent upon numerous factors which include
the type and concentration of micro-organisms, the pH and temperature
of the water, presence of interferring substances and whether or not
the organisms are protected from the disinfection solution by being
embedded in tissue cells, or clumps of tissue cells, or other material.
Therefore, various concentrations of disinfectants are required. Min-
imum concentrations of disinfectants are prescribed below.
Engineer operated mobile and portable water treatment units employ
coagulation and filtration as a part of the treatment process and are
capable of a high degree of removal of particulate material. When
those units are employed, sufficient chlorine will be added to the
water, preferably before coagulation so that the residual in the finished
water after 30 minutes of contact will be at least as much as that indi-
cated by the following table.
pH 30 Minute Free Chlorine
TABLE 2: Residuals in ppm
COAGULATION
RESIDUALS 0.75
75
.00
.00
.00
] .00
If adequate provisions are not made for accurate and frequent measure-
ment of pH, 5.00 ppm must be used.
-56-
The following guidelines were used in developing the above table:
1. The water to be treated would be natural surface or ground
water of average composition and not grossly or deliberately
contaminated.
Water temperature would be above the freezing point.
The prescribed concentrations of free chlorine should provide a
reasonable margin of safety for all bacteria and viruses patho-
genic to man, Parasitic ova would have been removed in the co-
agulation and filtration steps of the treatment process.
SAMPLE DESIGNS FOR TREATMENT SYSTEMS
SAND FILTER
Sand filtration does not make polluted water safe for drinking. But
a properly built and kept sand filter will prepare water for boiling
or chlorination that will make it safe. Trickling sand filters if
built properly and cleaned periodically, provide clear water that
must be boiled or treated with chlorine.
The following tools and materials are required:
Steel drum, 2 feet wide by 29 1/2 inches high
Sheet metal to make cover, 29 1/2 inches square,
9.8 feet of wood, 2 x 4 inches
Sand, 7 cubic feet
Gravel
Blocks and nails
Pipe to attach to water supply
Optional...valve and asphalt roofing compound to treat drum.
Surface water, from ponds, streams or open wells is very likely to be
contaminated with leaves and other organic matter. A trickling sand
filter can remove most of this organic material but will always allow
virus and other bacteria to pass through. For this reason it is al-
ways best to boil or chlorinate water after filtering.
There are several sand filters, but the trickiing filter is easiest to
set-up and understand. The trickling filter uses sand to strain the
organic matter from the water, although this does not always stop
small pieces of organic matter or bacteria. But in time, biological
growth forms on the top six inches of sand. This slows down the flow
of water through the sand but will trap more small organic matter and,
at times, up to 95 percent of the bacteria. But if not operated cor-
rectly, the sand filter can actually add bacteria to the water.
By removing most of the organic matter, the filter achieves the follow-
ing results.
1. Removes larger worm eggs, cysts, and cercariae, which are the
hardest to kill with chlorine.
2. Allows the use of smaller and fixed doses of chlorine for dis-
infecting, which results in drinkable water with less taste of
chlorine.
| ae
entrance helps
to prevent pipe
plugging and extends
TRICKLING SAND FILTER filter life
Figure 21
Valve not necessary
but helps to
regulate incoming
Pipe must be flexible f low
enough to allow
removal of lid
F ith Sheet metal roofing
Lid fits tight
or weighed
to prevent
Sm
blowing off Flat stones
Overflow to drain
area
| A
| ls
Frame
overhangs
at least
2 cm to
prevent
dust and
rain from
filter
Nail allows
air to circu-
late over sand PSP SSPS SELES
jSand depth *-;
f “60 om min, ::
. ‘ preferably 4
395 or more, --:
+3 or more
cm of
3 or more
pea-sized
blocks, high
enough to
allow pipe
or contain-
er’ under ——____
_ gravel
Drain should
be screened
a the point
of discharge
Water collection
Pipe or container
must fit close
to prevent entrance
of insects or dust
Outlet to
further
treatment and
storage
BEST COPY AVAILABLE
Makes the water look cleaner
Reduces the amount of organic matter, including living organ-
isms and their food, and the possibility of recontamination of
the water.
The unit shown in Fig. 2}should give about 1 quart of water a minute.
The drum should be of heavy steel and can be coated with asphalt ma-
terial so that it will last longer. The 2 millimeter hole at the
bottom regulates flow and must not be made larger (slightly less than
1/13th of an inch.)
It is important to use clean, fine sand, but not too fine. The sand
should be able to pass through a window screen and it is best to wash it.
The following points are very important in assuring that your sand filter
operates properly:
1. Keep a continuous flow of water passing through the filter and do
not allow the sand to dry out, as this will destroy the microorgan-
isms that form on the surface layer. The best way to insure a con-
tinuing flow is to fix’ the water intake so that there is always a
small overflow. Screen the intake and provide a settling basin to
help keep pipes from becoming plugged, which would stop the flow
of water. This will also delay your having to clean the filter.
Never allow the filter to run faster than 0.6 gallons of water a
minute per square foot, as it will prevent the growth of micro-
organisms in the sand and wash them out through the outlet.
Keep light from the sand surface but allow air to circulate, as
this will prevent the growth of green plant matter on the surface
but help the growth of microorganisms that aid the filtering action.
When the flow drops below daily needs, clean the filter. This is
done by scraping off and discarding the 1/2 inch of sand and lightly
raking or scratching the surface. After several cleanings, the sand
should be raised to its former height by adding clean sand. Before
doing this, scrape the old sand down to a clean level. Cleaning
should not be more often than every several weeks or even months.
WATER PURIFICATION PLANT
A crude water purification plant is described which uses laundry bleach
as a source of chlorine. Although lacking the reliability of a modern
water system, this manual plant will provide safe drinking water. Many
factors in this system depend upon operating experience. When starting
to use the system, it is best to have the assistance of an engineer ex-
perienced in water supplies. For constuuction details see section II,
C.
Operation
1. Mix concentrated bleach with water in the concentrate barrel
with all valves closed.
-59-
CHLORINATION SYSTEM
Fig. 22
MIXING TANK
¢
MEASURING STICK
CONCENTRATE
TANK a
O
QIOLUTION
DISCHARGE
BOX 7
u
|
Se
ae
i
UNTREATED
| WATER SUPPLY
3o,,
‘@ C \
a 40
DISTRIBUTION ~S al
TANK
a
Fill the pipe from the mixing barrel to the solution tank with
water after having propped the float valve in a closed position.
Allow a trial amount of concentrate to flow into the mixing
barrel by opening Valve #2.
Use the measuring stick to see how much concentrate was used.
Close valve #2 and open valve #1 so that untreated water enters
the mixing barrel
Close valve #1 and mix solution in the mixing barrel with a
stick.
Remove the prop from the float valve of the solution tank so
that it will operate properly.
Open wide the metering valve and valve #4 to clean the system.
Allow a gallon to drain through the system.
Close down the metering valve until only a stream of drops
enters the funnel.
(steps 2, 8 and 9 may be omitted after the first charging of
the system, if the pipe mentioned in the second step is not
permitted to empty before recharging the mixing barrel).
10. Open valve #3.
Trial and error must be used to learn how much concentrate should be
put in the concentrate barrel, the amount of concentrate to flow into
the mixing barrel and the amount of solution to allow past the funnel.
The result should be water with a noticeable chlorine taste in the
distribution barrel.
The flow into the funnel and the taste of the water in the distribution
barrel should be checked regularly to insure proper treatment.
CHLORINATION FOR POLLUTED WATER
Chlorination, when properly applied, is a simpte way to insure and pro-
tect the purity of water. These guidelines include tables to give a
rough indication of the amounts of chlorine bearing chemicals needed.
The amount of chlorine specified will normally make reasonably safe
water. Try to have your water treatment system inspected by an expert,
and the water itself periodically inspected.
The surest way to treat water for drinking is to boil it--see "Boiler
for Potable Water". lowever, under controlled conditions chlorination
is a safe method, and often more convenient and practical than boiling.
Water properly treated has residual free chlorine which resists recon-
tamination. The chlorine in water is not harmful since water with a
harmful amount of chlorine in it is extremely distasteful. Proper
treatment of water with chlorine requires some knowledge of the process
and its effects.
71
When chlorine is added to water, it attacks and combines with any sus-
pended organic matter as well as some minerals such as iron. There is
always a certain amount of dead organic matter in water, and almost
always live bacteria, virus, and perhaps other types of life. Enough
chlorine must be added to oxidize all of the organic matter, dead or
alive, and to leave some excess uncombined or "free" chlorine.
Some organisms are more resistant to chlorine than others. Two parti-
cularly resistant varieties are amebic cysts (which cause amebic dysen-
tary) and the cercariae of schistosomes (which cause schistosomiasis).
These, among others, require much higher levels of residual free chol-
rine and longer contact periods than usual to be safe. Often special
techniques are used to combat these and other specific diseases. It
always takes time for chlorine to work. Be sure that water is thor-
oughly mixed with an adequate dose of the dissolved chemical, and that
it stands for at least 30 minutes before consumption.
Since both combined and uncombined chlorine has an unpalatable taste,
it is best (and safest) to choose the clearest water available. A
settling tank, and-simple filtration can help reduce the amount of
suspended matter, especially particles large enough to see. Filtra-
tion that can be depended upon to remove all of the amebic cysts,
schistosomes, and other pathogen normally requires professionals to
set up and operate. NEVER depend on home-made filters alone to provide
potable water. However, a home-made slow sand filter is an excellent
way to prepare water for chlorination.
Thus, depending on your water, different amounts of chlorine are needed
for adequate protection. Measuring the amount of free chlorine after
the 30 minute holding period is the best way to control the process. A
simple chemical test using a special organic indicator (orthotolidine)
can be used. When this is not available, Table 3 may be used.
TABLE 3: TEST FOR PROPER CHLORINATION DOSAGE
Water Condition Initial Chlorine Dose in Parts Per Million (ppm)
No hard-to-kill Hard-to-kill organisms
organisms suspected present or suspected
Get expert advice; in an
emergency boil and cool
Very clear, few water first, then use 5
minerals ppm to help-prevent recon-
tamination. If boiling is
impossible, use 10 ppm.
A coin in the bottom Get expert advice; in an
of an 8 oz. glass of emergency boil and coo)
the water looks hazy, first. If boiling is im-
possible use 15 ppm.
72
In the chart, parts per million or “ppm” means the ratio of:
Weight of active material (chlorine)
Weight of water
In water supply terminology, ppm means exactly the same thing as
milligrams per liter or "mg/1"
The second chart,Table 4, gives the amount of chemical to add to
1000 gallons of water to get a solution of 1 ppm. Multiply the amount
of chemical shown in Table4 by the number of ppm recommended in Fig. 3
to get the amount of chemical you should add to 1000 gallons of water.
Usually it is convenient to make up a solution of 500 ppm strength
which can then be further diluted to give the chlorine concentration
needed. The 500 ppm solution must be stored in a sealed container in
a cool dark place, and should be used as quickly as possible since it
does lose strength. Modern chlorination plants use bottled chlorine
gas, but this can only be used with expensive machinery by trained
experts.
TABLE 4 CONVERSION OF PPM TO OUNCES PER 1,000 GAL.
Quantity to add to
Compound % by weight of 1000 gallons of water
active material to get a 1 ppm solution
High Test (Calcium hy-
pochlorite) Ca(0C1). 70% 1/5 ounce
Chlorinated lime 25% 1/2 ounce
Sodium hypochlorite 14% 1 ounce
(Naoc?)
Sodium hypochlorite 10% 1.3 ounces
Bleach - a solution of usually
chlorine in water 5.25% 2.6 ounces
FUNNEL WITH
FILTER MEDIUM
Fru TAP
a
FAUCET WITH
PIPE WiPAE
Bae
PAIL
HIGH
{ 2
WATT ULL LIL TLL LLL LL LL LLL
METAL PLATE
FOR DRAFT CONTRO
LESSON OBJECTIVE:
WATER TREATMENT
LESSON NO. 1
Describe and demonstrate how to estimate the
cost of the four methods used in treating water.
SUPPLEMENTAL MATERIALS /
INSTRUCTIONAL PROCEDURE RELATED READING
Treatment
Processes
Discuss the process of self-purification. Manual of Individual
Water Supply Systems
List and describe the four basic methods of p. 64-83.
water treatment: WHO Monograph Series #42
1) coagulation p. 171-193.
2) sedimentation Small Water Supplies
3) filtration pe 26-47. ©
4) disinfection.
Outline the essential components of sand
filtration and two chlorination units.
Estimate the costs of construction, operation,
and maintenance for these units.
LESSON OBJECTIVE:
WATER TREATMENT
LESSON NO. 2
Define the pollutants that must be eliminated;
(a) to provide esthetically pleasing and safe water; and,
(b) to prolong the life of the delivery system.
SUPPLEMENTAL MATERIALS /
INSTRUCTIONAL PROCEDURE RELATED READING
Peruissible
Levels of Chemical,
Physical and
Bacteriological
Pollutants
List and describe pollutants that are WHO Monograph Series #42
1) esthetically objectionable pe 46-54.
2) health hazards
3) contribute to the destruction of a
delivery system.
Establish permissible levels of concentration
for each of these cpollutants.
Recall the processes that will eliminate or
reduce these pollutants.
From a list of pollutants, have each student
state the undesirable property (ies) of each
and recall a method of elimination (if
applicable).
WATER TREATMENT
LESSON NO. 3
LESSON OBJECTIVE: Define the criteria that must be applied in
selecting the most economically feasible source.
SUPPLEMENTAL MATERIAL
INSTRUCTIONAL PROCEDURE RELATED READING
Criteria of Water| Review the basic requirements of a water Small Water Supplies
Supply Selection supply source. p. 8-14
Outline the criteria to be used in the
selection of water supply sources.
SECTION 3
PLANNING THE DISTRIBUTION SYSTEM
OVERVIEW:
A water distribution system is a large project requiring great expense in
time and capital. The health of the community will be affected by the
results of the project. The planning of the project is necessarily of
great importance, so as to ensure an economic, efficient, and safe result.
The trainee must be aware of the effects thet the existing facilities,
the community, the material and financial requirements, impose upon the
plans he must prepare prior to the start of the project. This section
covers these basic requirements of the planning for a water distribution
system.
~68-
SECTION 3: WATER DISTRIBUTION SYSTEMS
A. PLANNING THE DISTRIBUTION SYSTEMS
OBJECTIVE:
Develop a plan for a distribution system which
will meet the requirements of the given community,
utilizing the existing and proposed facilities.
Assemble a list of existing man-made facilities
and potential water sources.
Determine average demand; peak demand and when
it occurs; and the capacity of the system required
to meet both the present and projected requirements
of the community.
List the components and characteristics of the
proposed system. These include:
a. Water source.
b. Pumping equipment -- type of pump
Capacity of distributing reservoir or storage
Location of distributing reservoir with relation
to service connections.
e. Source of energy used in the system
f. Pipe sizes and pipe laying system
Choose the most economical and practical source
from among existing and proposed sources, with the
following characteristics:
a. Supplies required quantity
b. Requires no treatment or very simple treatment
c. System easily installed
d. Located in such a position that gravity can be
used as supply energy.
Choose most suitable site for the system facilities.
Choice guided by:
a. Proximity to and accessibility from residence
b. Safety from contamination
PLANNING THE DISTRIBUTION SYSTEMS
c. Safety from destruction
d. Availability of room for future expansion
Estimate the expected cost of construction, operation
and maintenance of the whole system.
Identify the source of finance, amount to be financed
and conditions related to the transaction.
FUNCTIONAL SKILLS:
1. Classify type of water sources
2. Measure the yield of different water sources.
Draw topographic map. Estimate distance and scale
this on a sketched map.
Classify climatic types and state construction
precautions, e.g., Tropical: heavy rain, insect
pests, etc.
Recognize useful local materials which can be used
instead of a relatively expensive imported one, e.c.
bamboo pipes.
Calculate projected population.
Calculate the capacity of a storage tank from data
on population and rate of individual consumption.
State factors which determine and guide the selection
of pumping equipment.
Recognize conditions which make a distribution
reservoir a necessity.
Decide what traditions can be changed without much
social discontent and which must be contended with.
Prepare a chart projecting expected costs of mater-
jials and labor, and estimate the required amount of
money.
TERMINAL PERFORMANCE TESTS:
1. Ina field exercise:
a. Classify and measure yield of various water
sources which exist in the area.
b. Describe the rest of the existing facilities.
PLANNING THE DISTRIBUTION SYSTEMS (cont.)
c. Sketch the system on a labeled map of the area.
d. Classify climatic types.
e. List at! local materials which can be used to
improve the system.
In a given community:
a. Estimate the present, and project the future
population.
Determine average daily demand, the peak demand
and when it occurs.
Cc.
Calculate the capacity required by the population.
From amonc many sources in the area, choose the
best one to develop, and justify.
Estimate the cost of establishing the proposed
system, and prepare a plan for financing that would
be feasible in a local village environment.
o]\«
WATER DISTRIBUTION SYSTEMS
PLANNING THE DISTRIBUTION SYSTEM
DESIGN
One of the most difficult and baffling problems in the planning of a small
water-supply system for a rural community is the lack of criteria upon
which a design can be based. The voiunteer needs answers to such questions
as: "What increase should be allowed for future population growth?"; "Should
provision be made for periods of peak demand?"; and "What about storage?"
Such technical questions have been thoroughly studied and standardized in
textbooks dealing with design of water supplies for urban communities.
However, for most rural, underdeveloped areas of the world, reliable design
guides have not yet been established. Furthermore, certain elements of
design are matters for local decision, depending on geography, local economy,
custom, and other factors.
The experience gathered from several rural water-supply programs has been
analyzed and is summarized below to serve only as a broad guide. It is
realized that there are wide variations in water-supply ~actice throuch-
out the world and that every designer should not apply b.indly the criteria
listed here; instead, you should be able to make a critical analysis of the
conditions and problems of the area under study and should develop appl ica-
ble criteria. In so doing, you should contact the health administration of
the area concerned with a view to consulting the minimum standards for de-
sign and construction which this administration may have issued through
its public health engineering division.
There is, however, general agreement on the following fundamental point;
in the design of rural water-supply systems, primary consideration should
be given to the protection of the quality of the natural water selected,
Since treatment should be considered only as the very last resort. This
requires the incorporation in the design of necessary sanitary safeguards,
beginning with the proper location of intake structures and pipes. Except,
in unusual circumstances, other engineering and structural elements should
be conceived around this need.
Before beginning the actual construction of a village water system, a wel]
defined plan needs to be drawn. The water system, when completed, will be
the result of a large commitment from all the local people, both in finances
and labor. To be sure that the system is what they want and need, careful
planning is a requisite. In planning the water distribution system, there
are seven major categories to be defined.
1. Existing Facilities: What already exists? How good is it? Can
it be made part of the overa'! system?
2. Size and Nature of the Community? How many people will be users?
How are they distributed? What customs or tracitions do they
have that must be considered in the overall plan?
a
3. System Capacity: How much water is needed daily? When are the
peak demands?
4. Water Source: What type of source will provide the most economical
and satiSfactory water for the system?
5. Proposed System: Location of facilities, pipes, outlets, etc.
6. Site of Proposed Facilities: An outgrowth of the proposed system,
What problems will there be ir obtaining the land needed for the
proposed facilities?
7. Financing: How will the materials be obtained? Will this project
be financed by government, cocoperatives, on a cost basis,etc?
EXISTING FACILITIES
From cata collected in Section I, you have already quite fully analyzed the
types of sources available, and evaluated each as a potential water source
for a water system. How you need to concentrate on matching the sources of
water to the existing community. This is accomplished by:
1. Adding to the topographical map already started, the distribution
of the users in the community.
2. Considering local customs and traditions regarding water uses, and
needs.
3. From (2) above, calculating system capacity requirements, and
system proposa!s to satisfy those requirements.
SIZE AND NATURE OF THE COMMUNITY
The proposed water system has to be built around the customs and traditions
of the community it will be serving. For example, if the social patterns of
the community are built around family structures, the system should strive
to provide sources of water to families, and not to the community through
centrally located water distribution facilities.
In many developing countries there are some traditions which appear “primitive”
to western culture. For example, in most parts of Africa, men swim upstream,
and women downstream. Or men first, then women. In Moslem countries women
do not appear in public unveiled. For an outsider, Peace Corps are outsiders,
to institute an acceptable new system in such areas, he has to study very
carefu'ly all such traditions and then modify his system to suit the com-
munity. If he cannot adjust the system, he should try to get his point
across by explaining to the people (or their representatives) why it is
important that he interferes with their life. For example: in the Moslem
community cited, the best plan would be to distribute water into houses
instead of establishing public wells. It must be emphasized that in order
to establish the most effective plan, a thorough study of the community
must be done by the planner. Usually a discussion with the local authorities
will y’eld a good result. Remember, when help is imposed from above, it
meets with resentment and failure.
84
In describing the community, care should be taken to determine population,
both present and projected.
Population growth is determined by:
1. Future economic developments in the community.
2. The character and location of the community in relation to other
population centers.
The presence or possible introduction of small industries into
and around the community (the installation of water schemwne itself
will cause population growth. )
A common acceptable estimate for future population growth in most rural
areas is a 50% increase in population over a ten year period, or approxi-
mately 5% per year. This should be the minimum figure upon which the
rural water-supply design should be based.
If this estimate appears too high for a particular situation, the system
should be designed for present population in a way as to allow for future
expansion.
Example on projecting population:
Original population 100,000
Increase over 10 year period 50% 50,000
Projected population in 10 years 150,000
Relationship between population and storage capacity:
The required capacity for a storage tank equals half the total daily
water requirement.
Total daily water requirement = average demand x population + larger users.
(Large users would include public centers, schools and factories. If
these are not in the community, then the last term is left out)
Storage Capacity = 1/2[average demand x design population + large users]
SYSTEM CAPACITY
The methods for evaluating each type as a potential water system source was
covered in Section I. For each source you will have to determine its yield.
This is the maximum quantity of water that can be drawn from a source in a
given period of time. To calculate the yield for a source of water you:
1. Draw a measured quantity of water from the source;
2. Time how long it takes the source to replenish the drawn qu tity;
3. Divide the amount of water drawn by the time taken to refill.
Yield is usually stated in gallons per minute. Below are examples for
estimating yield for various types of water sources.
85
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Boe S17 SEA YIPZ PIZI27 JOP 42TH &2O/
a. Cistern Catchment Yield
To estimate your catchment area, the minimum yearly rainfall and the
amount of water required by the family during one year, must be esti-
mated. Sometimes, the government meteorological section can give you
the minimum rainfall expected. If they do not, you can estimate the
minimum rainfall at two-thirds of the yearly average. Take the average
amount of water needed by the family for one day and multiply it be
365 to learn how much is needed for one year. Then use the chart to
find how much roofspace is needed (Fig. 24 )... Suppose you have a
rainfall of 60 inches a year and the family needs 20 gallons a day,
then...
2/3 x 60 equals a minimum rainfall of 40 inches a year
365 days x 20 gallons a day equals 7300 gallons a year
The chart shows that a catchment area of about 300 square feet is
needed to supply the family with enough water for one year.
b. Yield of Small Streams
This is a rough but very rapid method of estimating water flow for
smal] streams. The number of streams that must be used and the flow
variations are important factors in determining the necessary facil-
ities for utilizing the water. Here is a way to survey a water supply
problem quickly by allowing you to take rapid flow measurements.
The equation for stream flow is --- Q=KxAxV
Q = flow in gallons per minute (8.33 pounds = 1 gallon)
A = cross section of stream, perpendicular to flow, in square feet.
stream velocity, feet per minute.
a corrected conversion factor since surface flow is normally
slower than average flow. For normal stages use K = 6.4; for
flood stages use K = 6.7 to 7.1).
Fig. 25 Determine Stream Yield
87
Fig. 26 Cross Sectior of Stream
To find "A"... the stream will probably have different depths along
its length so select a place where the depth of the stream is aver-
age...take a measuring stick and place it upright in the water about
one foot from the bank...note the depth of water...move the stick
two feet from the bank in a line directly across the stream...note the
the depth...move the stick three feet from the bank, note the depth,
and continue moving it at one-foot lengths until you cross the stream.
Draw a grid, iike the one above, and mark the varying depths on it so
that a cross-section of the stream is shown. A scale of one inch
equals one foot is often used for such grids. By counting the grid
squares and fractions of squares, the area of the water can be esti-
mated. For example, the grid shown here has about 15 square feet of
water.
To find "V",..put a float in the stream and measure the distance of
travel in one minute (or fraction of a minute, if necessary.) The
width of the stream shouid be as constant as possible and free of
rapids, when measuring the velocity.
Example:
Cross section is 15 square feet.
Velocity of float = 20 feet traveled in 1/2 minute
tream flow is normal
Q = 6.4 x 15 x 20 feet 3300 gallons a minute
.5 minute
WATER SOURCE
Factors to be considered in the selection of a water source include the
following:
a. Purity of the source.
b. Proximity of the source to the community
c. Altitude of source above service connections
d.
Guide to
a.
PROPOSED
atte
Temperature variations of water from the source.
choosing a source:
First choice, a source that
requires no treatment
uses gravity for distribution energy
- requires minimum maintenance
is cheap to develop
- @.g. springs
Second choice, that which
- requires no treatment
- but must be pumped out and into the supply lines.
- e.g. wells.
Third choice, that which
- requires simple treatment
-uses gravity for distribution energy
- e.g. catchment cisterns.
Fourth choice, that which
- requires simple treatment
- must be pumped
- e.g. rivers
SYSTEM
SELECTING SITES FOR THE SYSTEM'S FACILITIES
1.
és
de
Source - must be near to the community (see above),
Pump station - should be above the highest probable flood level;
or be suitably protected against flood.
- should be accessible at all times
- should be large enough to meet future expansion.
- should have suitable topography
- should be well protected from possible sabotage-e.g.
by enclosing it within an industrial type wire fence
with a locked gate.
Storage Tanks - should be centrally located
- If possible, should be put on the highest ground in
the area.
83
PUMP SELECTION
The most important considerations in selecting a pump are:
The skill of the operators and maintenance men available
The iritial cost of pump and driving equipment
The cost of operation and maintenance
The capacity and lift required
Availability of power to operate the pump
The sanitary features of the pumps available commercially.
Type of source in which the pump is to be installed; including the
depth of static water level from ground surface.
8. Reliability of equipment, and availability of spare parts.
NOM WP —
The following is a general guide to the selection of pumps for rural
water-supply systems:
1. Structure of the pump
a. All movable parts above ground and easily accessible are easy
te maintain. Suitable for areas with no skilled maintenance man.
b. If skilled maintenance men are available, first choice should be
pumps with submerged cylinders.
Type of power available; Power-driven pumps must be of high effi-
ciency to reduce the cost of power.
Design of the pump: The pump design should be flexible enough to
be used in a wide range of sources. There are some pumps which
must operate under the conditions for which they were designed,
e.g. deep-well turbine and centrifugal pumps.
Repairs: The selected pump must be of a type for which repair and
replacement parts are easily obtainable.
Sanitary Standards: The pump and equipment must be constructed as
to prevent contamination of water either at source or enroute to
storage. Specific sanitary conditons to be considered:
a. Pump head should be designed tc prevent contamination from
environment from reaching the water-chamber of the pump
b. The base should be waterproof.
c. The pump should not need priming
Information required when ordering or inquiring about a pump.
1. The inside diameter of hole or casing in which the pump is to be
installed.
The static level of water in well, measured from ground level.
The desired output in gallons per minute.
ADVANTAGES AND DISADVANTAGES OF VARIOUS TYPES OF PUMPS
VELOCITY
TABLE: § ;
POSITIVE DISPLACEMENT
Types
pumps
hand
plunger type
motor, wind dri-
ven, plunger type
chain or contin-
uous bucket
centrifugal
deep-wel]
turbine
jet
Usual well
pumpin
depth tre)
22-25 ft shallow
well; up to
600 deep well
22-25 ft shallow
well; up to
600 deep well
Depends on valve
being lifted and
type of power
10-20 ft
50-300 ft
15-20 ft below
ejector
Capacity
Gallons/
Minute
3-15
10-25
4-20
Very wide
range: 2 to
unlimited
Very wide
range:
25-5,000
Efficiency
range (%)
Low; can be im-
proved with
double-acting
cylinders;
252-60%
Low; can be im-
proved with
double-acting
cylinders;
25%-60%
Good:
50%-85%
Good:
65%-80%
Low: 402-60%
Operation
Very Simple
Simple
Very Simple
More difficult;
needs attention
Simple; air locks
can cause trouble
Maintenance
Simple, but val-
ves and plunger
require atten-
tion; more dif-
ficult when pump
cylinder is in
the well
Same as hand
pump; mainten-
ance of motors
sometimes diffi-
cult in rural
areas
Simple, but
attention is
necessary
More difficult
and constant;
skilled atten-
tion fs neces-
sary
Simple, but
attention is
necessary
Low, but higher
when cylinder
is in the well
Low, but higher
when cylinder is
in the well
Reasonable
Reasonable
Higher, espec-
tally in deep
wells
Reasonable
TABLE 5 (Cont.) ADVANTAGES AND DISADVANTAGES OF VARIOUS TYPES OF PUMPS
POSITIVE DISPLACEMENT
VELOCITY
Types of
pumps
hand pumps,
plunger type
motor, wind dri-
ven, plunger type
chain or contin-
uous bucket
centrifugal
deep-wel]
turbine
Power
Hand or animal
Wind, motor
Hand, animal,
wind, motor
Motor
| Motor
i
Advantages
Low speed; easily
understood by
unskilled people;
low cost
Low cost; sim-
ple; low speed
Simple; easy to
operate and
maintain
Efficient;
wide range
of capacity
and head
Good for small-
diameter bore-
holes; ease of
operation
Moving parts on
surface; ease of
operation
Dis-
advantages
Low efficiency;
limited use;
maintenance
more difficult
when cylinder is
in the well
Low efficiency;
limited use;
maintenance
more difficult
when cylimder
is in the well
Low efficiency;
limited use
Moving parts
and packing
require
attention
Moving parts in
well; rather ex-
pensive; requi-
res good main-
tenance and op-
eration
Limited appli-
cation; low effi-
ciency; moving
parts require
attention
The lowest water level expected during pumping.
The desired water pressure at ground level.
The type of power available (If electric, specify voltage, phase,
frequency, etc.)
7. The total depth and nature of source.
PUMPS AND PIPES
Generally, pump size determines appropriate pipe sizes, and vice versa.
Pumps
The types most commonly used in small community water systems
are:
1. Hand-or power-operated reciprocating pumps with the cylinder
above the ground.
Power-operated centrifugal pumps with pump mechanism above
ground.
Hand-power-, or wind-operated reciprocating deep-well pumps,
with cylinder in the well.
Deep-well turbine pumps driven either from the surface or from
a submersible electric motor.
Jet pumps, power-driven at surface.
Hydraulic rams
Air-lift pump, operated by power-driven compressor on the
surface.
Classification of pumps (see Table § )
1. Displacement a) Reciprocating
b) Rotary
c) Chain
2. Velocity a) Centrifugal
b) Jet
3. Airlift
4. Hydraulic rams
Where various pumps are used:
1. Reciprocating plunger - in wells mainly. The most commonly used
pump.
10.
Ǥ2-
Semi-rotary pumps - for low lift - e.g. fro
to overhead tanks. g m wells and cisterns
Rope-and-bucket systems - in open dug wells. Either hand or wind-
less operated.
Chain-bucket pump - in open dug wells.
Chain-and-plug bucket.
Multicellular band pump.
Centrifugal pump - in deep wells.
Jet pump - in deep wells.
Airlift pumps - in drilled wells and wells with irregula d
also for pumping muddy water. wie sete
Hydraulic Rams - in springs, streams and rivers.
Examples of various pumps.
A -= Supply—litres/minute
B ~ Difference in elevation between ram and supply-power head
C = Length of drive pipe
D = Difference in elevation between ram an
vated—pumping head
E -= Total length of supply pipe
F = Stand-pipe, necessary in case of exceedingly long drive pipe
d highest point to which water is Co be ele-
Under the proper circumstances—a situation similar to that shown, in which the supply
of water is considerably in excess of the needs, and is situated so that the ram can be locat-
ed well below the supply—the hydraulic ram can be an excellent solutior to a pumping
problem.
When writing to manufacturers about ram sizes, the information in items A, B, C. D,
and E is necessary. With this the factory will be able to recommend the correct size,
feasibility, etc.
Fig. 27 Hvdraylic Ram
96 eee ts
BEST COPY AVAILABLE
-83-
28 Typical Installation of Jet Punip
= Water being return-
ed from pump above
Water from well
being sucked up into
throat (D) by high-
velocity discharge
(C)
Jet assembly
Water line from pump to nozzle
Rising water
Centrifugal pump
- Pressure-regulating valve
+ Discharge pipe
Height of water pushed by jet
Suction by centrifugal pump (about 4.5-6 m,
or 15-20 ft)
IO*™mOINSD
Fig. 29 Displacement Pump Operation
A = Down-stroke: Cylinder above plunger fills while valve at base of cylinder closes, and vaive in plunger
opens.
B = Upstroke: Cylinder full of water above plunger is expelled while, at the same time, valve at base of
pump opens, fillirg cylinder below plunger. As plunger rises, a vacuum is formed below, pulling water
into the cylinder
When the cylinde: Is above ground, a foot valve is necessary to avoid priming.
97
BEST COPY AVAILABLE
Adapied by _ permirsion from Graham. F.D. & Emery, T. J. (1942) Audel’s Phombers’ and sicam fters’ guide, No |,
New York, p. 2748,
Fig. 30 Elementary, Single Acting Force Pump
In addition to the foot and bucket valves of the lift pump, a head valve is provided.
In operation, during the up-stroke, atmospheric pressure forces water into the cylinder; during the
down-stroke, this water is transferred from the lower to the upper side of the piston.
Fig. 31
Centrifugal Pumps
This is the best and simplest arrangement for centrifugal pumps. Power unit may be
electric Mets, ur imerna: combustion engine.
B«.t-driven centrifugal pumps are common but introduce belt maintenance. Necessary
in order to get the correct engine-pump speed ratio.
The manufacturers’ recommendations for operation and maintenance should be followed
4)
ee BEST copy AVAILABLE
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~85-
3. Choose a pipe size, so that velocity through it will be about 6
feet per second.
4. Estimate the pipe friction loss “head" (10 foot "head" represents
the pressure at the bottom of a 10 foot high column of water) for
both suction and discharge piping, using the following table.
TABLE 6 Average friction loss for water flowing through pipe when velocity
is 6 ft./second.
| Pipe inside
diameter j as 2" “I a” 6" 8" i ag 24"
F = approxi-
mate friction
100 ft. pipe
F x length of pipe
100
Friction Loss Head -=
Any bends, valves, constrictions, and enlargements (such as passing
through a tank) add to friction. The equivalent pipe iength of
such "fittings" in the pipe line should be added to the pipe length
used in the friction loss equation.
5. Obtain "Total Head" as follows:
Total Head = height of lift + friction loss head.
Using a straight edge connect the proper point on the "Total Head
(ft.)" line with the proper point of the "Discharge U.S. gallon/
minute" line. Read motor horsepower and pump size (diameter of
discharge outlet), choosing the printed values just above the
straight edge.
Note that water horsepower is less than motor horsepower. This is be-
cause of friction losses in the pump and motor. The nomograph should
be used for rough estimate only. For: an exact determination give al]
tnformation on the flow and piping to the pump manufacturer. He has
the exact data on his pump for various applications. Pump specifica-
tions can be tricky especially if suction piping is long and the suc-
tion lift is great.
Example:
Desired - to pump 100 gallons/minute 50 feet high, no fittings
Pipe Size - 3" (for 6 feet/second)
reference: Handbook entry "Velocity of Water in Pipes”
Friction loss head - about 3 feet.
Total head - 53 feet.
Pump size - 2"
Motor horsepower - 3 H.P.
39
VUNP SIZE AND WOREPOWER REQUIREMENT
3,904 so80
E300 2000 F-21000
7 0003-1) e006
F200 So Sao
— x 200 +} 200 t
‘ >, >
Let g “i= 8
Sear wy \y
+ BO t
% $
60 ~ D
x x
S p
3 > 2
' ~ FR
~o
o
= ry
a
Po)
Pe)
bo 2
,)
+ SO Q é in
an res
a . s
a 2
ae
F NS 2
t 20 © st,
? fk
%
t art h
L1o %
ig aos te
- Oo
r8
< 0.02 Yeo
ADAPTED FRom WNomocgracnic Cuners psy GCA. Kouann
WPYRtanr 1951. MoGemw Hr Boo Co. Ten.
By PERMImTION
or CUSEC
FT®/sEc
DISCHARGE
US. GAL/MIN
DISCHARGE
PumMP SsIz€ fovrseT DIA IN)
ee
vom
If you plan to use human power for the pump, figure that a man can
generate about 0.1 H.P. for a reasonably long period and 0.4 H.P.
for short bursts. From this and the total head, you can predict
the flow you should design the hand pump for.
Pipes
Most commonly used pipes are made of:
Galvanized wrought-iron and cast iron
Asbestos
Transite (mixture of cement and asbestos fiber)
Lead
Copper
Plastic
Bamboo stems and other related tropical plants
Wood-stave, made out of light wood
Sa noanonwew
Measuring diameters: The diameter of a pipe is determined by
measuring the inside diameter.
FINANCING THE PROJECT
The stock reply to questions about financing is that the country, state,
province, or community concerned is too poor to afford the cost of needed
improvements. Upon investigation, however, it often turns out that public
money is being spent for projects which are of much less importance and
which cannot possibly give the same returns as those obtained when the
same amount of funds is invested in the construction of public water-
supplies. There is usually a way to obtain long-range financing for rural
water-supply programs if the individuals concerned with the problem wil]
look far enough for a good case to present to their legislators or to
financial institutions. Lona-range pians have been effective in many
countries throughout the world, both in the Western and Eastern Hemispheres.
Most of them are the result of the work of a few people who have succeeded
after painstaking efforts, in convincing the right government or bank of
the importance of sanitation work.
In almost a’] successful programs, federal] or central governments have
shouldered the responsibility for financing the construction of small rural
water projects. In many cases this decision will have been made by the
time you begin. Because of the lack of credit on the part of most rural
towns and villages and the. absence of a system of financing public works
through direct loans from private banking institutions, the central govern-
ment must usually fill the role of provider of funds. In some places the
states or provinces co-operate. In many countries, the normal pattern is
for the central government to loan the necessary funds directly to a local
community at a low rate of interest or to make a partial grant, with the
community and state jointly, supplying the remainder. Loans or grants are
made on the basis of projects presented through proper channels for approval
by state or federal engineers. A sanitary engineering section in a central
health department would be qualified and might be available to provide this
technical service to rural communities.
In many financing plans the community is expected to contribute labor,
land, local materials, and some services to the project, because these
may be easily obtained locally and are often very reasonable in cost to
the community. As a matter of fact, where the town or village is receiving
a grant, it should at least be required to contribute those things that are
available locally. Such a system offers an excellent opportunity to foster
in the community a sense of ownership and pride in something which its mem-
bers had to toil hard to achieve.
Co-Operative projects are not always appreciated by government administra-
tions, which often fail to understand their great advantages and sionifi-
cance from the standpoint of public relations and interest. It is true
that such projects are slow of execution and that great patience and tact
are demanded if they are to be carried through to successful conclusion.
However, they are indispensable when large numbers of community water-
supplies are to be constructed in areas of poor economic possibilities.
In some areas original cost estimates of new water-systems have been re-
duced by as much as 50% because the local people were able to furninh all
the unskilled labor as well as services such as transportation, office
Space, warehouses, etc., plus all the local materials required.
Thus, you, by taking the initiative, can successfully, over a long period,
accomplish a great deal in the reatm of rural water-supply development.
When estimating the cost for the project, you should carefully calculate
costs for the following items:
1. Materials - List all materiais needed
2. Labor
3. Transportation
As a general rule of thumb, labor should be about 25% of the cost of the
project, materials about 70%, and transportation the remaining 5%. Al-
though this will vary for particular situations, large variations from
these guidelines should be carefully examined.
In countries where water systems have been built, it has been found that
the total cost of the water system can be recovered in 3 to 5 years by the
reduction in cost of sickness and death from water-born diseases and the
actua! money outlay to buy water from vendors. In money, only, the capital
savings for a ten year period can be as high as 800%. In addition to finan-
cial savings, a pure water system can reduce 75% of the sickness and death
caused by water-borne diseases as well as increasing the amount of pure
water available seven-fold. This information will be appreciated by local
people and government administrators and should be used to promote necessary
financing for rural water-supply programs.
LUF 102
LESSON OBJECTIVE:
PLANNING THE DISTRIBUTION SYSTEMS
LESSON NO. 1
To determine existing frcilities which may
be useful as part. of the planned system.
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS
RELATED READING
aater Sources
oographic
vocations
Lecture on various types of possible water
sources and their characteristics.
Show how to use tables in determining the
yield of a source.
Demonstrate how to measure velocity of water.
Ask students the conditions under which a
pump is necessary to distribute water.
Briefly mention pumps used in large systems
(stress it is not the concern now),
Lecture on the characteristic features of
pumps most often used in Rural Water Supply.
Ask students to name materials most commonly
used for pipes.
Add local materials omitted by the students,
Demonstrate how to measure pipe diameters.
Show general areas where the Peace Corps
will go.
Pictures of various
sources. Chart on
characteristics of source
Water sources, floats,
current meters, weirs.
tables on yield.
Individual Water Supply
Systems, p. 24-52.
Models of pumps.
Photographs and/or
drawings of pumps.
Chart giving character-
istics of pumps.
WHO Monograph Series #42,
Chapter 4.
Samples of pipes from
various materials,
measuring scales & gauges
World Map
Atlas of climatic regions
of the world, showing:
relief, vegetation,
seasonal rainfall and
temperature distributions.
PLANNING THE DISTRIBUTION SYSTEM
Lesson No. 1 (Continued)
Local Materials
Lecture on climate of each region.
Discuss in class possible hindrances to
construction work.
Group them on the board under causatives.
Lecture on trade-off values: e.g., quality
vs. expenses to achieve convenience.
Discuss in class the materials which can be
adapted to suit an improved distribution
system.
LESSON OBJECTIVE:
PLANNING THE DISTRIBUTICN SYSTEMS
LESSON NO. 2
To choose the most suitable source for development
aid select a suitable site for the system facilities.
TOPIC
SUPPLEMENTAL MATERIALS
INSTRUCTIONAL PROCEDURE RELATED READING
selecting Water
source
lecting the
te
Discuss the possible combination of Section on Sources.
characters a source can have.
Let each student draw the characteristics of
the source he would choose first.
Discuss the feasibility of each proposal.
Formulate a guide to quick choices. WHO Monograph Series #42
fo. 34-35.
Discuss the importance of proper locations Suggested Design Criteri:
of facility sites. for Waterworks in
Recreationel Areas,
Sections 2°4 and 9°3.
Draw a guide to site selection.
PLANNING THE DISTRIBUTION SYSTEMS
LESSON NO. 3
LESSON OBJECTIVE: To select pumping equipment most suited
for use in rural areas.
SUPPLEMENTAL MATERIALS /
INSTRUCTIONAL PROCEDURE RELATED READING
Characteristics Ask students to recall characteristics of Section on character-
pumps. istics of pumps.
of Fumps
Discuss with students what would be the best Pumps and/or pump
guide criteria for choosing a pump. models.
-93-
PLANNING THE DISTRIBUTION SYSTEMS
LESSON NO. 4
SSON OBJECTIVE: To describe the community to be served;
specifically, the aspects that affect the plan.
SUPPLEMENTAL MATERIALS
INSTRUCTIONAL PROCEDURE RELATED READING
Lecturem how to estimate the population of
a community.
Show how to calculate projected population WHC Monograph Series F42,
and relationship between population and p. 42-43.
demand,
itions and Discuss the importance of long established
l Structure traditions.
Discuss what traditions are likely to clash
with the planned system and how to avoid
such a clash.
“nic Standard Discuss the connection between occupation and
water demands.
Relate type of houses te distribution systems.
Compare availability of skilled labor in !.S.
to underdeveloped countries.
Discuss how to seJect workers for the project.
-94-
PLANNING THE DISTRIBUTION SYSTEMS
LESSON NO. 5
LESSON OBJECTIVE: To prepare a chart projecting expected costs of
material and labor. Estimate the required amount of
money and how to raise the money. ’
SUPPLEMENTAL MATERIALS
INSTRUCTIONAL PROCEDURE RELATED READING
an
Cost Discuss how to estimate the cost of the WHO Monograph Series #4
project. pp. 28-33.
Finaucing Discuss various methods. Financial Statements
Section 6
~95-
SECTION 4
CHARACTERISTICS Of AN ADEQUATE SYSTEM
OVERVIEW:
There are many technical problems and factors to be considered in the
design of a distribution system. The layout of the system, the sizes of
the pipes, the loss of pressure, and many other factors must be considered
in the actual plannina of tne system.
This section provides the trainee with an understandina of the character-
istics of an adequate system. With this understanding he will be able to
plan the technical aspects of the project and avoid mistakes in the con-
struction phase of the program.
BEST COPY AVAILABLE
109
-96-
SECTION 4: CHARACTERISTICS OF AN ADEQUATE SYSTEM
OBJECTIVE: Define and evolve a detailed plan for the con-
struction of the basic components in an adequate
system.
TASKS: 1. Draw to scale the plan and profile illustrating
the relative locations of the component parts
of the system.
2. Prepare a detailed account of the characteristics
of the chusen source, and state how it is to be
developed.
3. Analyze data (collected in Section 1) and decide
what type of treatment processes are required.
4. Describe how water will be transferred from the
source to treatment plant or distribution reser-
voirs, and the sanitary precautions to be taken.
5. Describe the safety precautions to be taken
during the construction and operation of the
treatment plant; i.e., to avoid recontamination
and protect personnel.
6. Determine the storage requirement for the system.
7. Based on the location of the tank, select the
material(s) to be used in its construction.
8. Identify sanitary and servicing provisions to
be followed in constructing the storage tank.
9, Decide which system of distribution best suits
the community.
10. Determine the required pressures at service
connecticns and design the pipes and joints
for distributing.
see ges 9 gs sh ong ef pewis Sinn amingg 340°
° > ee ie “oe « coess 2
uid! BEST COPY AVAILABLE
110
-97-
CHARACTERISTICS OF AN ADEQUATE SYSTEM (cont)
FUNCTIONAL SKILLS:
1. Recall the essential components of an adequate
system.
2. Draw topographic, plan, and elevation maps. List
data which should be included on a topographic
map of an adequate distribution system. Measure
elevation of points.
3. Identify safe water.
4. Recall functions of component parts of a treat-
ment plant. Use high and low lift pumps. De-
scribe and evaluate the various treatment pro-
cesses described in Section 2.
5. Recall relationship between distribution systems
and various community patterns.
6. Calculate required head, headloss. Read from
tables the relationships between pipe sizes,
pipe joints, and headloss.
7. Recall relationship between different pumping
facilities and size of community.
8. Identify the relevant structural properties of
materials.
9. Identify properties of coating paints.
10. Recall safety standards to be maintained in the
construction and operation of a system.
TERMINAL PERFORMANCE TESTS:
1. For a given community layout, design a distri-
bution system which best suits it, and draw to
scale the plan and profile showing the locations
of the various component parts of the water dis-
tribution system, pipe lengths and size, and
valve locations along the line.
2. Given a number of water samples, identify those
defined as "safe".
3. Ina given treatment system, state in detail
what happens as the water passes through the
successive stages.
M3 11]
-9-
CHARACTERISTICS OF AN ADEQUATE SYSTEM (cont.)
4.
Giver, a source and treatment plant, and/or
distribution reservoir some distance apart,
list all sanitary precautions which should
be taken while transferring the water.
List all sanitary and personnel safety pro-
visions to be taken into consideration while
planning the construction and operation of a
treatment plant.
Choose the appropriate materials for construc-
ting storage tanks,
a. underground
b. on the ground
c. above the ground
Determine the difference in height between a
given storage plant and service connection, and
calculate the required head and headloss in the
section.
From given tables, choose pipe sizes that will
deliver water with a specified residual pressure
at a service connection distance ( ) units away.
-99-
WATER DISTRIBUTION SYSTEMS
CHARACTERISTICS OF AN ADEQUATE SYSTEM
ESSENTIAL COMPONENTS OF AN ADEQUATE SYSTEM
SOURCE
The source of water for the distribution system must meet the require-
ments that have been established for quantity and quality. The source
will meet the quantity requirement by simply being able to provide
enough water to meet the demand. If no single source can satisfy
this requirement, the construction of storage tanks and/or reservoirs
can be built to compensate for this deficiency. The quality require-
ments for drinking water are aenera!ly established by local or national
health departments. (If none exist, you should review the minimum
standards for drinking water discussed in Section 2) If no satis-
factory water sources exist, you should carefully consider the con-
struction of wells before choosing a source that would require exten-
sive treatment. Although the distribution of water from a central
source by means of pipes to each village house is a goal towards which
every community should strive, the construction of wells (if necessary)
would be an incomplete, but very satisfactory step toward that goal.
Once satisfactory water has been located, it is essential that care
be taken not to contaminate the water during its distribution. To
insure the preservation of potable water, the following protective
measures shoulc be taken:
1. Wells and pump bases should be sealed so that surface water
is unable to enter the well;
2. Water used to prime pumps must not be polluted (when possible
use pumps that do not need priming).
3. Only trained workers should be responsible for maintaining the
system once it has been built. (Initially, care should be
taken to select workers who are healthy and free from communi-
cable diseases).
TREATMENT FACILITIES
In selecting a water source, the goal is one needing no chemical treat-
ment (other than disinfection) prior to use. As stated earlier. if no
such source already exists, explore the possibility of a well construc-
tion program.* When an acceptable-but-less-than desirable source is
the only alternative, a treatment plant will need to be part of the
distribution system. The purpose of the plant will be to upgrade the
quality of water that does not meet drinking water standards. The
methods for evaluating water and selecting treatment processes is
discussed in Section 2.
* For further information refer to the Peace Corps training manual
on the Construction of Water Wells
BEST COPY AVA
113 EST COPY AVAILABLE
-100-
DISTRIBUTION RESERVOIR
In small distribution systems, whether the water is obtained by gravity
or by pumping, it is always desirable to provide a distribution reser-
voir. The main reasons are:
1. Hourly variations in the rate of consumption are more easily
satisfied (in small systems, such variations may be three
times the average hourly consumption and sometimes more) ;
2. Adequate pressure can be maintained throughout the distribution
system;
3. Adduction pipes between the source of .upply and the reservoir
may be repaired without interruption of the village water ser-
vice.
4. Provisions may be made for fire protection.
5. Pumps can be operated uniformly throughovt the day. (Such pumps
may be much smaller than would be required otherwise).
6. The size of the adduction pipe between the supply source and
the reservoir can be made smaller than would be necessary if
the village were fed directly from the water source.
7. Fluctuations in peak periods of demand can be more easily ob-
served and compensated for when all water is dra . froma dis-
tribution reservoir.
The first consideration when designing storage is the capacity which will
be provided. This to a great extent depends on the type of supply, and
is influenced by two main factors--the necessity of catering for peak de-
mand periods, and the provision of reserve to cover normal breakdown or
maintenance interruptions.
Conditions vary in different parts of the world, but a typical pattern
of draw-off in a village is as follows--30% of the day's supply between
7 a.m. and 8 a.m.; 30% between 5 p.m. and 6:30 p.m.; 35% during the
other hours of daylight; and 5% between sunset and sunrise. Local cus-
tome will produce local variations; for instance, in Moslem countries
the demand during Ramadan will be high at about 3 am., and in other
parts of the world where Monday is the traditional "wash-day" the Monday
morning draw-off may be equivalent to the total supply of another day.
These considerations must be taken into account when assessing the ex-
tent and duration of peak draw-offs; this must then be balanced against
the rate and periods of water delivery.
When water is supplied by gravity from the source it is most economical
in cost, as well as most satisfactory from an operational aspect, if a
constant flow is maintained throughout the twenty-four hours. Obviously
in such a method of working a smaller delivery main is needed than if
larger quantities are required in shorter periods. When electricity ‘s
used for pumping it is usually most economical to operate for about
twenty hours a day, leaving the pumps idle during the peak hours of elec-
tricity demand. With diesel- or gasoline-driven pumps, the cost of atten-
dance (generally continuous with such engines, but normally unnecessary
with electric motors) becomes an important factor and one shift of eight
hours, or two totalling 16 hours, is a frequent method of operation.
114
It is quite common to find schemes designed to operate with a single
shift of 8 hours initially, increasing to 16 hours when the demand
rises later. More than 16 hours a day is not desirable with such
engines; not only do labor costs increase but the wear on machinerv
working continuously throughout the day and night becomes excessive
and the life of the plant is correspondingly shortened.
To determine the amount of storage that will be required to provide
uniform serice througliout the day, you must estimate three factors:
1. the hourly consumption throughout the day (measured in gallons)
2. the proposed hours of pumping (as explained above, this is
determined by the type of equipment available)
3. the pumping capacity of the system (gallons per hour).
GENERAL REQUIREMENTS FOR AN ADEQUATE SYSTEM
An adequate system is one which will deliver the required amount of potable,
palatable water to all outlets at a prescribed or satisfactory pressure.
MAPPING THE PROPOSED SYSTEM
A drawing or map and a profile of the distribution system should be
made showing the location of each component in relation to others (see
Section 1 on drawing topographic maps). Below are a number of ways
that the distribution system layout can be illustrated.
TO
DISTRIBUTION
a
7 —_
PROFILE
FIGURE 33
LAYOUT OF A COMBINATION W/TER SYSTEM
-102-
SYSTEM CAPACITY et
Once these factors have been determined, the storage capacity can be
determined. The following guidelines should be considered in arriving
at adequate storage capacity:
1. As a rule-of-thumb, the storage required should be approxi-
mately equal to a days consumption of water.
2. Minimum capacity should be large enough to handle morning and
afternoon peaks. In no case should it be less than half a
day's supply.
3. If it is not possible to store a day.’s requirement, long per-
iods of pumping should be adopted with no interruptions.
4. Where possible, ground storage is preferable.
PIPES
In selecting pipes, the following suggestions should be followed:
1. The velocity of flow of water should not be more than 6 ft.
per second in main pipes; and 3 ft. per second in feeder pipes.
2. Pipe sizes for mains must be at least 2 inches in diameter.
3. Using the nomograph attached, determine the pipe size which
will deliver water at a desired rate.
Pipe Flow Calculation
This chart helps determine the flow of water from several sizes
of pipe when you know the height of the water source.
The nomograph applies to steel pipe. Fiq. 34 should be used
to find the equivalent pipe length. The length of pipe run can
be paced off. One can crudely sight with their eyes and attempt
measuring the reservoir height. To make this measurement with
any accuracy requires some type of surveyor's instrument.
To use the nomograph, first find the number of pipe diameters
there are in the pipe lengths. This is accomplished by dividing
the pipe diameter in inches into 12 x pipe lengths in feet; or
divide the pipe diameter in centimeters into 100 x the pipe
length in meters.
Then with the straight edge connect the pipe diameter on the d
scale in inches (1 inch = 2.54 cm) with the reservoir height in
feet on the h scale. Mark on the index scale where the straight
edge crosses. Now connect this point on the index with the number
of pipe diameters in the pipe length as calculated and observe the
reading on the Q scale. This will be the discharge in gallons per
minute.
Rt
~
oa
AAAAAK
2e,
oe
/h-Available Head, in Feet of Weter
in inches
{ eee Pe he OO ee he
es
3 $ ;
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7
/
#3
AF
387
phitias
i
§
25 ae pe
/
& «=
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:
mish t
/
48
L/D-Length of Pipe, in Diameters
CALS Gee ee
/
a
haute | t ! T
oa od
an
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Oona
| T ee i ee Be 229 £erre
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Lassttiserdsngsl 1 Lala dads
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od
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a
Fig. 34 Pipe Flow Calculation
Pump Size and Horsepower Requirement
For preliminary sizing of a pump used to lift liquid to a known height
through simple piping, follow these steps:
1. Determine the quantity of flow desired in gallons per minute.
8.33 pounds = 1 gallon.
2. Measure the height of the lift required (from the point where the
water enters the pump suction piping to where it discharges.)
117
Example:
Assume a reservoir height of 30 feet, a pipe size of 1 1/2"
diameter and 100 feet in pipe length, what will the discharge
rate be?
First divide the length by the diameter each in inches
1200
r.5 = 800
now convert 1.5 on the d scale with 30 feet on the h scale and
make a mark on the index scale. Connect this mark with 800 on
the = scale and read the flow as 60 gallons per minute on the
Q scale.
Headloss Calculation
How to compensate for the headlosses due to pipe fittings: Express
in terms of the equivalent to the length and size of pipe which
would produce an equivalent loss if, instead of adding fittings,
additional pipe was added. Note in table below that headloss
due to pipe fittings can be neglected for relatively long pipes.
TABLE 7
Allowance in equivalent length of pipe for friction
loss in valves and threaded fittings
Diameter . af a Coupling
of fitting or straight
ee @oon@
apPPwoee
_—
RELATIONSHIP OF DISTRIBUTION SYSTEM TO COMMUNITY
ARRANGEMENT OF THE NETWORK
There are two main systems uf distributing water in a comunity:
Dead-end System
This consists of direct lines from the mains to the outlet without
inter-connected lines (see Fiq.35 ).
Evaluation:
1. Easy to instal}
2. Takes less material for pipes
3. Best for small, unplanned community layout.
4. Disadvantage: If water not used often nay breed
bacterial at the stagnant end.
RVICE LINE
a BRANCH $ CEC
a “fser"
faa ae tee
oe _
Fig. 35 Dead-End System
Loop System
In this, the ends of all the supply lines are connected $0 there
is continuous flow of water in the system while it is being drawn
from any point in the loop (see fig.36 )
Evaluation 1. No stagnant water
2. Less vulnerable to breakdowns since valve arrange-
ments may be made to re-route the flow of water,
isolating smal] trouble areas.
Suitable for well-planned community.
FEEDERS
|
Fig. 36 Loop System
Generally, in a large community, the loop system can be used
around main residential or business areas; and the dead-end
system for the rest of the system
The network of pipes should be arranged so large primary mains feed
sinaller secondary pipes. Branches or feeders carry water from mains
to service connections. Service pipes carry water from the branch to
the building.
HEAVLOSS AND DISTRIBUTION SYSTEMS
HEAD
In planning a distribution system it is desirable to draw water at
a tap with a good pressure- not too high nor too low. Required head
is the height (or depth) of water which is required to produce a given
pressure. Pressures are expressed in pounds per square inch (psi) or
in height units (ft.).
——_— To.
wa- Water Head Water
aoe ee
Fig. 37 Head Measurement
Retation of Pressure and head: from the definition of head and some
traulic factors, it can be shown that 2.31 ft. of water exurts 1] psi
at its base or 1 psi exerted at base of water solumn will reise it 2.31 ft.
Example: Calculate the pressure exerted by a colum. of water 100 ft
at its base.
.3] ft. exert 2 psi ‘
00 7t. exert x 100 psi = 43.3 ps
ya} |
HEADLOSS
This is the reduction of pressure in a pipe which may be due to friction
in pipe and pipe fittings, or valves, and can be expressed as a change
in head. Allowable headloss is the difference, in feet of water, be-
tween the tank elecation, and the elevation of service connection, plus
the required head at the service connection. i.e. allowable headloss =
Elev. tank - (elev. service connection + required head)
Example: Given elevation of tank = 750 ft.
elevation service conn. = 665 ft.
required head (-20 psi) = 46.2 ft.
allowable headloss = 750 - (665 + 46.2) = 38.8 ft. of head.
Note: The required head recommended by U.N. survey must be at least
10 psi (13.1 ft) for small water supply systems. For multi-
storied houses, minimum should be 70 psi (91.7 ft). 20 psi (46.2 ft)
is a reasonable figure to work with.
120
Actual headloss is the headloss which actually occurs in pipe and
joints. It must not exceed the allowable headiess. The pipes and
joints selected must have a total headloss less than the allowable
headloss.
LESSON OBJECTIVE:
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.
CHARACTERISTICS OF AN ADEQUATE SYSTEM
LESSON NO. 1
To outline the general requirements for a system
to be qualified as adequate.
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERI
RELATED READING
'
Definiti of an
Adequate System
Component Parts:
Relative Locations
(a)
Source and Pumping
Facilities
(b)
Treatment Plant
(c)
Storage
Discuss in class and draw out a definition
of "an adequate system".
Demonstrate how to draw the map and profiie
of a system,
As an exercise let each student draw the
profile from a sample map.
Discuss the requirements for quality and
quantity of water at source.
Discuss the relationship between type of
source and type of pump to be used.
Draw safety provisions required.
Discuss the need for water treatment.
Visit a treatment plant and note the
relative location of treatment stages.
Compare safety requirements to that at
source.
Discuss the need for storage facilities and
how the storage capacity is related to the
size and the commnity.
Discuss the various storage systems and the
effect of location on them.
Ask students to outline what particular
attention be paid to maintaining the quality
of the water.
iS 122
Section 3
Map of a Village
Section 1
Drawing boards.
Section 1
Section 3 on
Pump Selection.
Section 2 on Wa\
Treatment.
WHO Monograph Serig
Chapter 4
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CHARACTERISTICS OF AN ADEQUATE SYSTEM
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LESSON OBJECTIVE: To determine the relationship between the distribution
system and headloss in the system; and design oa distribution
system suited to o given community.
SUPPLEMENTAL MATERIALS /
TOPIC INSTRUCTIONAL PROCEDURE RELATED READING
Definitian of Define head and headloss. Water in tank
headloss Measuring Scale.
Demonstrate how to mensure head. Chart. of Headloscs vs.
Pipe Size. Teoles cf
Show how to calculate headloss. equivelent pipe lengths
and valves and fitting,
Relationship Demonstrate the effect of valves and Flevated water source;
ictween Headloss threaded fittings on the water flow in a4 long and short. pipes,
} the Dirtribu- pipe. valves and joints.
n Pipes
Show how the adove loss may be compensated
for in the plan.
Relationship Lecture on how to design a distribution
Between the system to fit a given community.
Community Layout
and the Distribu-
tion System
123
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SECTION 5
CONSTRUCTION TECHNIQUES
OVERVIEW:
The preceding sections have covered the background knowledge that a
trainee must have to recognize and evaluate sources of water and to plan
the development of a distribution and treatment system. Regardless of
the planning, a system is only as good as its construction allows. This
section covers the techniques needed by the volunteer to adequately con-
struct the system he has designed.
The emphasis of this instructional material is on doing. The trainee
should learn by doing, for no amount of lecture can impart “how", it is
only through doing that the trainee will be able to understand when, for
example, concrete is wet enough.
This section covers Construction with concrete, and specific projects for
building and installing the major components of a treatment and distri-
bution system.
124
-111-
SECTION 5: CONSTRUCTION TECHNIQUES
OBJECTIVE: Develop, purify and distribute water in a given
community.
TASKS: 1. Oevelop the selected source to meet the requirements
specified in the design.
2. Build an intake site and install intake pumping
facilities.
3. Test the water so obtained for sanitary standards.
4. Build a treatment plant appropriate for treating
water from the above developed source.
5. Construct a storage tank with a predetermined capa-
city; apply protective coatings on tank and pipes
against heat, chemical corrosion and insect pests.
6. Lay and connect pipes for the conveyance of water
from the distribution reservoirs (storage tank) to
the various service connections.
FUNCTIONAL SKILLS:
1. Recall characteristics of various types of sources.
2. Dig, drill, and bore a well in such a way as to ob-
tain maximum yield from it.*
3. Mix concrete of a desired strength.
4. Build protective casing for a well, spring, or
pump base.*
5. Build a small pumphouse to specification.
6. Determine conditions which would require low or
high lift-pumps for intake of water.
7. Build a screen of wire or other materials of desired
mesh around an intake terminal in a pond, lake,
stream, river or any other reservoir to keep out
silt, water life and vegetation, and the stress from
water flow.
8. Recognize relevant treatment processes for water
from a given source.
9. Construct or assemble the various treatment processes
such as, filters, sedimentation tanks, etc.
“This skill is optional, depending on the scope
of the particular training program.
af! 125
-112-
CONSTRUCTION TECHNIQUES (Cont.)
10. Connect various treatment stages in their proper
order.
11. Read and follow an instruction manual.
12. Put together a prefabricated structure, using
reinforced concrete, painting or spraying the
needed parts, and welding, soldering or riveting
pipes together.
TERMINAL PERFORMANCE TESTS:
1. At a given location develop a water source from
underground water which will meet the water de-
mand of the community.*
2. Given raw materials required to produce concrete,
mix concrete of a specified strength and show it
meets the specification.
3. For a given source, install an intake pump.
4. Given the plan and all materials, build a house
over a well (or pump).
5. Ina given distribution system, state where you
would use:
a. Low lift pump
b. High lift pump
6. Design and build a model of an intake terminal
of a system if the source is:
a. Lake or pond
b. River or stream
c. Well or cistern
7. For a given source of water, carry out purity
tests and state what kind of treatment the water
requires.
8. Construct separately the various component parts
of a treatment system and test the efficiency at the
the various treatment stages.
9. Given a model treatment plant in the laboratory,
assemble the various treatment units in order of
performance (e.g., sedimentation-filtering).
*This skill is optional, depending on the scope
of the particular training program.
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CONSTRUCTION TECHNIQUES (cont. )
10. Given a peckage of all parts of a tank or pump
(or the respective models) with an accompanying
instruction manual, assemble tie parts and test
for proper fittings.
—_ ae ne emo —->
11. Given a storage tank and its gross weight, design
a foundation for its elevation to a given height
above the ground.
12. Construct a tank of specific volume with rein-
forced concrete.
13. Given a storage tank and distribution pipes,
coat to protect them from:
a. Corrosion from ground and atmospheric chemicals
b. Excessive ‘heat
c. Insect and other pests.
14. In a workshop, join several pipe lengths using
different methods at each joint, e.g. welding,
riveting, etc.
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WATER DISTRIBUTION SYSTEMS
CONSTRUCTION TECHNIQUES
SCHEME
The following sketch shows the major components of a distribution system
that must be planned and constructed. In total, this represents a com-
plete water distribution system, indicating the location of each component
relative to the others.
Source Pipe Pump Pipe Storage &
House reatment
=
@
TO SERVICE
CONNECTIONS
1) Development 2) Building house 1) Constructing tank
2) Intake 2) Installing pump 2) Installing puri-
fication systems
Fig. 38 Distribution System Layout
CONCRETE
The material which is used at almost all stages is concrete. For this mat-
ter, an extensive description of concrete in construction work will be in-
cluded for convenience.
Concrete is a strong, durable and inexpensive construction material when
properly prepared. After concrete has set, there is no simple non-destructive
tive test to evaluate how strong it is. Therefore, the entire responsibil-
ity for making concrete a strong material in accordance with specificaitons
rests with the supervisor on the job and the people who prepare, measure
and mix the ingredients, place them in the forms, and watch over the con-
crete while it hardens.
The most important factor in making strona concrete is the amount of water.
Beginners are likely to have too much. See the entry on a slump cone for
further details.
The proper proportion of all the materials, designed for the application,
is essential. The concrete calculator will help give the proper propor-
tions and amounts for your job.
Properly graded, clean, sharp aggregate and sand is required to make good
concrete. When we glue two pieces of paper together, we spread the glue
evenly and in a thin layer, and press firmly to eleminate air holes. In
concrete, the cement is the glue, and the sand and aggregate the material
being joined.
By properly graded we mean that there are not too many of any one size grains
or pebbles. Visualize this by thinking of a large pile of stone al] 1 1/2"
in diameter. There would be spaces between these stones where smaller peb-
bles would fit. We could add to the pile just enough smaller stones to fil)
the largest voids. Now the voids would be smaller yet, and even smaller peb-
bles could fill these holes; and so forth. Carried to an extreme, the pile
128
would become nearly solid rock, and only a very small amount of cement would
be needed to stick it together. The resulting concrete would be very dense
and strong.
Sharp aggregate and sand is desirable. Smooth, rounded stones and sand can
make fairly good concrete, but sharp, fragmented particles work better be-
cause the cement as a glue can get a better grip on a rough stone with sharp
edges.
It is extremely important to have the aggregate and sand clean. Silt, clay,
bits of organic matter will ruin concrete if there is very much present. A
very simple test for cleanliness makes use of a clear wide-mouth jar. Fill
the jar about half full of the finer material available, the sand and smal]
aggregate, and cover with water. Shake the mixture vigorously, and then
allow it to stand for three hours. In almost every case there will be a
distinct line dividing the fine sand suitable for concrete and what which
is too fine. If the very fine material amounts to more than 10% of the
suitable material, then the concrete made from it will be weak.
This means that other fine material should be sought, or the available ma-
terial should be washed to remove the material that is too fine. This can
be cone by putting the sand (and fine aggregate if necessary) in some con-
tainer such as a drum. Cover the aggregate with water, stir thoroughly,
and let stand for a minute, and pour off the liquid. One or two such
treatments will remove most of the very fine material and organic matter.
Another point to consider in the selection of aggregate is its strength.
About t
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