Document text
DOCUMENT RESUME
ED 243 656
SE 044 387
TITLE
SPONS AGENCY
PUB DATE
CONTRACT
NOTE
AVAILABLE FROM
PUB TYPE
Water Purification , Distribution and Sewage Disposal,
Appropriate Technologies for Development; Reprint
R-29.
Peace Corps , Washington , DC . Information Collection
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 20526i *
Guides - Classroom Use - Guides (For teachers) (052)
EDRS PRICE
DESCRIPTORS
IDENTIFIERS
MF01/PC11 Plus Postage.
*Construc t ion (Process ) ; Design Requirements ;
Developing Nations; Learning. Activities;
Post secondary Education; Public Health; *Toilet
Facilities; *Training Methods ; ; _ Training, Object iyes ;
Units of Study; *Waste Disposal; Waste Water; *Water
Resources; *Wa_ter Treatment
*Peace Corps; Water Distribution
ABSTRACT 7Z
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 uni.tsu 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 construct ion 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)
*******************************************
* Reproductions supplied by EDRS are the best that can be made *
* from the original document. *
*****************************
ERLC
iiS^RyBSiew collbctio^ & exchange
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established so that the strategies and technologies devel-
oped by Peace Corps Vblunteers, their cs>-workers f and their
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you and your fellow development workers.
Peace Corps
3
ERIC
[CATION,
^Ser pui^ie^ON, distribution mid 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:
OVS/Technical Resources Divisibn-5/69
OPDElVlnf ormat ion Resource Services-11/69
Inforrnation Collection & Exchange-4/79
4
TABLE j
SECTION 1
WATER SUPPLY SOURCES AND TREATMENT
WATER SUPPLY SOURCES
OVERVIEW. ........................... .. .......... ......... 1
Background Information. .......................................... ..4
Evaluation of Sources. .. ... . . . . , ±1 . . . . ........................ .14
Factors Influencing the Qu?.lity of Water. ........................ .21
The Quantity of Water. .......................................... .23
Types of Sources. ... .................................... .24
Development of Water Sources. .. ............................... .31
The Basic Requirements of a Water Supply. ........................ ;40
Selection of the Source of Supply. ........... '. ................... .41
LESSON PLANS. : 44
SECTION 2
WATER TREATMENT
OVERVIEW. ; 48
Self PuriflMtlQh........^,^ 51
Basic Steps Mn Treating Water.,..,^ 52
Sample Designs for Treatment Systems .56
LESSON PLANS. .64
SECTION
PLANNING THE DISTRIBUTION SYSTEM
67
71
Existing Facilities ; 72
Size /and Nature of the Community. ................................ .72
Systtm Capacl ty . . . . . . . . . . . . . . i . . . . . . . . . . . . i . . . . . . . . . . . . . . . . ; ; ; i ;73
Wateft Source; ................................................. -76
Proposed System^. ..... . ................. i................ .77
Financing the Project. 87
LESSON PLANS. . ........ .i 89
OVERVIEW.
SECTION 4'
CHARACTERISTICS OF AN ADEQUATE SYSTEM
OVERVIEW. L .. ... ... ..... ........................... • -95
Essential Components of an Adequate System... .................... .99
General Requirements for an Adequate System.^. .................. .101
Relationship of Distribution System to Community. ............... .105
Headloss and Distribution Systems. . ............................. .106
LESSON PLANS 108
SECTION 5
CONSTRUCTION TECHNIQUES
OVERVIEW. 110
Scheme. . . , n|
Concrete. .. .. • ]I*
Construction at the Source....... JZ1
Construction at the. Pumping Station .122
Construction at the Storage Facility .123
Coi.structloh on Supply bine. ... .> .133
LESSON PLANS ........... -. -. V. 1 35
ERIC
SECTION 6 Of , NATION AND MAINTENANCE
OVERVIEW .139
Water Source Maintenance and Inspection. ........................ .144
Regulations for Installing New ' Service Connections. ........... ;148
Regulations for Cleaning the Distributions System. .............. .148
Inventorying for Operation in Erriergehejes. ........ .............. .148
Types of Financial Statements for Small Waterworks .............. .151
LESSON PLANS... 154
SECTION 7 SCOPE OF DISPOSAL SYSTEM PROJECTS IN HOST COMMUNITIES
OVERVIEW^.,.,., ...^ 160
Public Healtfr Importance of Excreta Disposal 163
How Disease is Carried from Excreta.^. . , 163
The Characteristics of an Adequate System 165
Possible Sanitary Measures in Rural Areas ....165
Soi 1 and Ground-Water Pollution. .... . .171
Location of Latrines and Other Excreta Disposal Facilities. . . . . ..172
Sludge Accumulation and the Life of a Pit Privy. ................ .173
Community Participation. ........... 5 ............ , ......... • . .... A75
Family Parti cipati on. . ... . .... ... ... ........................ .176
Role of Heal I th Department and Other Agencies .................... .1 77
Public Versus Private Latrines.*. . ............................... .178
Human Factors. ......................................... .'. ....... .179
LESSON PLANS 181
SECTION .8 THE PRIVY METHOD OF EXCRETA DISPOSAL DESIGN FOR
A VILLAGE
OVERVIEW. 184
The Sanitary Survey. ...................................... < 188
The Pit TPrivy. .................. A 189
Example Privy Designs. «. 195
Latrine for Village Use. 199
Thailand Water-Seal Privy : 204
LESSON PLANS * 208
SECTION 9 WATER CARRIED SEWAGE SYSTEMS CONSTRUCTION AND.
MAINTENANCE
OVERVIEW. . . ........... 1 ^ .......... i .................. 211
"I he Septic Tank. ............................................... ..219
Cjperation and Maintenance. ..................................... . .229
LESSON PLANS. . .................................................. .236
BIBLIOGRAPHY. 242
6
TABLE OF CONTENTS
FIGURES
Fig. 1 Contour lines. , .... ...................................... .5
Fig. 2 Symbols for Topographic maps .5
Fig. 3 Contouring from spot elevations ..5
Fig. 4 Plane Table mapping . . . . . s 9
Fig, c , Nomenclature of unconsolidated rocks.................... 12
Fig; o Turbidity. test, ^ . i i ............................................. 22
Eicj. 7 Geological formations. . , ............. .27
Fig. 8 Occurrence and distribution. of sub-surface water 28
Fig. 9 Shallow well in free water zone. 30
Fig. 10 Well tapping confined water. .................................... 30
Eig. 11 Direct Intake, with hose bh bottom of water source, ............ .33
Fig. 12 Surface Intake with hose burled 1n_ gravel -f 1 1 led pit ...33
Fig. 13 Use ofbucketon end of surface Intake.,^ 34
Fig. 14, Improvised dam for Impounding small streams, .34
Fig. 15 Baffle dam for protecting Inlet strainer. ...................... ,35
Eig . IB Float-type. surface Intake* with anchors... .35
Eig. 17 Gravel -filled gallery intake 36
Fig. 18 Spring Inlet. . . . 36
Fig . 19 Typical dug well with suction pump. ............................ .38
Fig. 20 Finished drive point well .39
Eig. 21 Trickling sand filter...... .57
Fig. 22 Chlori nation system 59
Fig. 23 Chlorination system ....................................... .63 -
Fig. 24 Cistern catchment yield. ..................... ; ................. .74
Eig. 25 Determine stream yield. 7.5
F1g. 26 Cross section of stream 76
Fig. 27 Hydraulic Ram.. ................................................ .82
Fig. 28 Typical Installation of jet pump. .............................. .83
Eig . 29 Di spl acement Pump Operat i on 83
Fig. 30 Elementary, single acting fofce pump .84
Fig. 31 Centrifugal pumps. ............................................. .84
Fig. 32 Pump size and horsepower requirement.............. .86
Eig. 33 Layout of a combination water system 101
Fig. 34 Pipe flow calculation ....> .............. 103
Fig. 35 Dead-end system. .............................................. .105
Fig. 36 Loop system - 105
Eig. 37 Head Measurement. 106
Fig. 38 Distribution system layout ....................................114
Fig. 39 Concrete Calculator, ......................................... .117
Fig. 40 Concrete mixing 118
Eig. 41 Slump cone 113
Fig. 42 Slump cone plans . . L . ......................................... 120
Fig. 43 Small intake structure. ....................................... .122
Fig. 44 Ground. level reservoirs............... 123
Eig. 45 Typical spring collection-chamber for towns 124
Fig. 46 Properly protected spring. ..................................... 124
Fig. 47 Properly protected spring {11). ............................ ...124
Fig; 48 Elevated storage tank... , 125
Eig. 49 Water-level indicator for elevated storage tanks 126
Fig 50 Storage tank. . . ............................................ 127
Fig.
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M»
tig.
Oc
tig.
DO
Fig.
D<t
Fig.
cc
Fig.
00
Eig,
D /
Fig.
ru
Dp
Mm.
rig.
AH
OU
Kig.
61
Fiy.
62
F"| g •
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F i cj .
Fig.
Mij.
DC
t i
F.g-
y /.
c o
DO
Fig.
/■ n
o9
Fig.
7 A
Eig.
/I
Fig.
7 0
Fi.g.
73
F1g.
7/1
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Fig.
75
Fig.
77
Eig.
78
Eig,
79
Fig.
80
Fig.
o 1
Fig.
QO
oc
tig-
Fig.
83B
Fig.
84
Fig.
ob
Eig.
86
Fig.
87
Eig.
08
Pin
Fig.
90
Fig.
91
Fig.
92
Fig.
93
Fig-
94
Manhole covers ^ ....... ; ....... ; ;".'.* 127
Typieal valve and box 127
Piping installation .128
Cistern f i 1 ters • 128
Chlorlnstion system. . . . . .« 13Q
Boiler for potable water. 132
Standard pipe fittings.. 1 34
Treatment system flow chart. ..... ... .145
Transmission of disease from Excreta. . ........................ .164
Cesspool Lined with large stones. ...159
Seepage p ' i t . ^ . * ... 1 ...... . , . :<-. 16?
Typical household septic tank : . 170
Typi cal layout of septic-tank system. . . . . ............. .171
Movtniei.l cf pol 1 u tiori in underground water. ................. 1 72
Sludge accumulation in pit latrines. ..... .... - ..174
Privy designs ensuring privacy and separation of the sexes 180
Types of Privy Shelters......... ... rJ . ........ . . .194
Various parts of a sanitary, privy. ............................ .197
Typical round and square bases............................ 198
A hewn- log privy base 198
Latrine for village use,,.,..,... 199
Inner to mi ot ldtrine (top view). ... .................... .200
inne/ form and steei rim in place oh base...... 200
Latrine bowl mold. , .S • • • '201
Views of construction of slab for latring. .................... .202
Views of construction of slab for latrine. .. > ................. .202
Views of construction of slab for latrine 202
Views of construction of slab for latrine ........202
Views of construction of slab for latrine. ............ ...... .202
Views of construction of slab, for latrine. . ............ .202
The completed casting.................. ' 203
Sketch of the. completed privy .204
Backward flushing trap ............................. .205
Forward flushing trap. 205
Bowl core handles ............ I ......... ? 206
Privy frame. . , * . • .207
Privy slab outline. ......................... • -20/
Methods _of- / making percolation tests .. ....... 217
Longitudinal section of single compartment concrete
septi c tank, .. t ............ 223
Concrete silo stave tank,. .224
Cover slab for septic tank. .-. ................................. -226
Concrete block tank. ... ...... - : ... i ■ • • ■ -227
Closed or continuous tile system arrangement for level ground
Serial distributlpn system arrangement for sloping ground 232
Typical distribution box. ............... . 235
8
TABLE OF-
TABLE 1 Classification of unconsolidated materials ;.ll
TABLE 2 Coagulation Residuals. ....... ... ............................... .55
TABLE 3 Test for proper chlorinatlon dosage. .61
TABLE 4 Conversion of ppm to ounces per 1,888 gal. .................... .62
TABLE 5 Advantages and disadvantages of various types of pumps 78
TABLE 6 Average friction loss for water flowing through pipe. .......... .85
TABLE 7 Allowance in equivalent length of pipe for friction loss
in valves and threaded fittings.......................... .104
TABLE 8 Repair record chart. . ...... ... . . .. .146
TABLE 9 Maintenance chart of a G.M. diesel 71.. ...147
TABLE 18 Pit privy capacity for a family of five 195
TABLE 11 Volume and depth for rural latrine. 196;
TABLE 12 Bistarices from various sources to disposal facilities. ........ .213
TABLE 13 Required absorption area for given percolation rates
TABLE 14 Required capacities for septic tanks serving individual
dwellings 214
TABLE 15 Required capacities for .septic tanks serving canps and day
schools .............. ..221
lABCE 16 Capacities* dimensions and materials for septic tanks. ........ .228
TABLE 17 Absorption trench area and spacTTig. ........................... .230
PREFACE
WATE R PURIFICATION, RiSTRIBUTION > AND SEWAQE DISPOSAL Is designed to B '
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 kb turn out Volunteers who can perform effectively 1n
the field.
Each logical unit of Instruction 1s sub-divided Into the following
categories: ■ „ 1
OVERVIEW v - A statement summarizing the general significance of
the material to follow, and points requiring special
emphasis.
OBJECTIVE - 'A definition of the goal to be achieved by the trainee
for that unit of Instruction. "
TASKS the steps to be followed. to accomplish the objective.
FUNCTIONAL The knowledge and skills needed to be able to perform
SKILLS the tasks.
TERMINAL The means of evaluating the ability of the trainee to
PERFORMANCE perform the skills needed to complete the- tasks in
TESTS order to accomplish the i objective -.
RELATED Content jhformatl brv describing the knowledge and skills
INFORMATION needed to perform the tasks correctly.
LESSON . Suggested guidelines for providing Instructional time
PLANS for the essential areas Of each unit.
Al though we have followed a typical pattern of presentation, offering
logical units of Information, 1t is important to ke*ep in mind that the
manual is to be used in preparing Volunteers for a program and pat no
single unit can possibly stand alone. All are interrelated and need to
be included 1n a systematic presentation. Its value as a refer mce tool
will come after the skills have been learned and the Volunteer Us over-
seas. Once in the field, the objectives and tasks can be used by the-
Volunteer as ah outline description of how the project should proceed.
During the early stages of the project, valuable suggestions and opinions
were offered by VITA Volunteers, Robert Fortman. James Patterson, Morton
Hllbert 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 05 thanks; \
A deep bow to Ethel Carlson, who managed to keep all the horses_pn the
tracks and Barbara Ille^ who spehtfcroany hours trudging through first
draft scratehlngs. *• ... £ -
Special appreciation 1s extended to Messrs* Richard Will jams and MiJce
Furst, United States Peaee Corps, and Ken Kal§, Executive Director, VIJA,
Without their vision, support and encouragement, this manual would not have
been written.
Finally, "errors and oversights must.be credited to. . .
Schenectady* New- York
April 18, 1969
Michael J. GlowacM
Project Coordinator
11
ERIC
SECTION 1
■If
WATER SUPPLY SOURCES
OVERVIEW :
The purpose of a water supply system 1s to distribute water to the locations
where It is needed, A source of water must be found which 1s adeqiiatein
quantity and qual ity. An uriderstand]\rig,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 farnillari zq. the student with these basic geologi-
cal properties. Also included is Information on making topographic maps to
aid in this .evaluation:, this background, knowledge 1s_ then_u$ed_ to describe,
water sources and how they can be develdped to provide potable and palatable
water for distribution by the water supply system.
The learhingactivl ties in this section are primarily field exercises. The
trainees will be in the field seeing actual examples of water sources. They
will examine, samples_pf the various rock types. __The; emphasis should be on
individual participation. It is only through this ex that a trainee
will be able to again recognize suitable sources when he is overseas.
-2-
WATER PURIFICATION, DISTRIBUTION, AND 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 arid consult people with a knowledge
of the same Information ontthe types and loca-
tions of the sources.
2. Determine the location of any 1akes\or ponds,
cisterns, springs, rivers, or wells Srf th re-
spect to the community. \
3. Identify any lakes, ponds* rivers* springs*
wells* or cisterns.
4. Roughly sketch tlie topography between the
sources arid the community.
5. Plot the location of any housfs* 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 amburit. arid the variation
in the amount of water available from each
source.
7. Icleritlfy the natyre arid quaritlty of
physical, bacteriological, and chemical
pollutants *of each source.
8* Identify the extent to which any developments
would improve the quality or quantity of the
various potentially productive sources.
9. Detenrtirie the cost of developments for each
potential source.
FUNCTIONAL SKILLS:
1. Interpret ari«J make simple topographic maps.
2. Use a compass.
3. Identify ^the various types of water supply
sources.
13
HATER SUPPLY SOURCES (coifit.)
1.
2.
3.
4.
5'.
6.
7.
Identify the basic rock arid soil types
arid know the hydrologlcal properties of
each.
Know what factors, Influence the quantity
of a given water supply source.
Know wha t_ factors ^fn^ueTCe^the ^aftty
of a qiven water supply source.
Identify physical pollutants (the extent
of chemical and bacteriological pollution
will be determiried by laboratory analysis) .
Identify what developments can significantly
reduce .-pollution or improyethe yield of the
various water supply sources.
L1$t the relativecosts of various types of
source developments.
Given a compass, draw a simple topographic
map of any prominent 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 arid 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 given tybes of source developments.
14
-4-
HATER SUPPLY SOU RCES AND TREAT MENT
WATER SUPPLY SOURCES
BACKGROUND INFORMATION
TOPOGRAPHIC MAPPING
Tn planning a water distribution- or sewa ge disposal system, the
~ 1 ayoiit Tlif~tfie~cbnfnun1 ty"wTtnrr«pect tcr any-water_sup^Ty-s^urces
must be mapped. When no maps of an area are available, _crude
sketch maps are sufficient. Such maps shouTd indicate the
approximate placemerit_bf _any_man-niade structures* Tivestock
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 grourid_ relief (topography)
from points whose elevations above sea level are known,
the method is called "contouring from spot elevations". The
data might have been bbtair.ed_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 contourinq.
1 All points lying on a contour are of the same ilfvatipn
above (or Below) a reference point. However, one contour
need hot satisfy alV CTe points of equal elevation; ^eg.
adiacerit_hilltops"o7 similar relief might require sepa-
rate, closed contours each shbwing_comparable levels.
Some contours mav 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.
2 With rare exceptions, the_contour Interval Is constant for
the map area and is defined as the vertical dlstancebe-
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 surfacebas Identity. Ten-foot^
twenty-foot^ fifty-foot and 100-fbpt Intervals are common.
The interval is selected to best show the shape of the sur-
face at the desired horizontal scale w1thout_requir1ng^an
% unnecessary, unreadable number of lines. The relief of^the
area to be mapped also Influences the choice of the contour
Interval .
3. 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.
15
t
ERIC
-5-
4.
Closed depression contours are hachured on the lower
s1de._ They are used when all points within the line
are below the level of the _]1ne._ Obviously they are
only required to show depressions which are completely
surrounded by high ground. Sullies and river valleys
are not usually closed on the downstream side and
therefore are hbtJllustrated by depression contours^
A depresslon contour takes Its value from that of the
lowest, topographically adjacent regular contour.
In contouring gullies and valleys, the contours vee
In the upstream direction. Becafeful to confine the
stream to the lbwestpart of Its valley by passing
the stream through the notch of the vee.
Fig. 1 Contour Lines
Contours are broken where numbering 1s necessary, to
Improve readability.
6. The use of some degree of "artlstlc.llcens^lsrecpm-
mehded 1n contouring. __Dp_npt attempt to just satisfy
thf poiht data. Try to make the trend of a contour
reflect the trend of Its neighboring contours.
Tunnel
L -i . I
Strrama
Mnnh
Private road
si
Mine or quarry
Intermitlrnl --
ftlmmi
IWnch mar*
\-/ m U r
Trail
Howl* and
SUtc line
Lake or pond
Countour line*
i i
Church School
(ounljr line
Inlormiucnl loki
F1g. 2 Symbols for Topographical Maps
ERIC
ie
Fig. J CONTOURING FROM SPOT ELEVATIONS
C
1. 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.
at
17
-7-
Gehera 1
In making a erode 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 i_d1staht object In. a path and
determination of its position relative to a present mark will serve
for proper orientation.
Determining Pace?
tay out a one hundred foot interval on level ground, art 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 sticky and this stick
in. turn used to nieasure the 100 _fe|t.__Be1hg_careful to work nor-
mally* the map maker then determines the number of . paces over the
100 foot interval for qach slope. By division* it Is then possible
to finda number of feet in an average pace for uphill, level, and
downhill slopes.
faking 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 neaM rigs, three things must be done; {1}
the compass must be leveled, (2) the point sighted mustfce centered
exactly in the sights * and J3J the needle must be brought to rest.
In a sketch map^ contours are used only to show the relative dlffer-
ericeMrv elevation arid rthe nature of ^ the- topography. - H- Is unneces-
sary to know the elevation of a given contour or to cohnect all of
them. Contours can be drawn arbitrarily to Indicate that a hill 1s
steep^ a stream riins in a given direction* the ebninuniiy is uphill
from a water source, etc. A realistic sketch ijnapcaOl drawri_by__
estimating the relief of an area around a point and then proceeding
to a point oritfie periphery of this area. Plane table mapping may
prove more adequate when more detailed maps are required.
Map Making Using a Plane fable
A description is given 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:
... - Piane fable
Paper.
Pencil
Ruler
Pins
Tape measure (optional)
Spirit level '(optional )
is
The first step Is to decide on ascalffbr 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
canbe spliced together when completed. As an example. If one
wanted a man 2 1/2- feet long to portray an area whose major
distance Is 1/2 mile, 264Q_feet, then a scale of 166 feet to
the inch would be convenient,
Taper should be placed_pri_the plane tableTnd, the plane table
oriented on or near some principal feature of the map, thatis,
a path, road, creek street, etc- A_p1h_ should then be placed
vertically in the spot pnthe finished map where. this location
Is desired. The plane table should be made level -by use of
a spirit level, if available- The_table_should be rotated to
a prbper_orientatipn,^that_1s,.sa that^the diction will ap-
pear on the finished map 1n:the desired way,__Hpw_ sight along
the first pin to another principal feature which is visible
from thetable location (a bend in the road* a hill orany ___
feature that wit! tie the map together), moving_the second pin
into the line of 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 the direction. defined by the two pins.
Measure the distance to_the feature observed either by pacihg
or with a tape. Scale- this distance along the l_1he_drawn i _
starting at the initial pin. Repeat this process for other
priric1pal_featuref 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 moveover
the territory in a convenient fashion. For example - % follow a_
lane or creek or some feature which, ties things together. Set
up the plane table bver_th1s_ppint and reorient the table. Do
th1s_by putting pins into the map at the present ahd_ previous _
locations. Next rotate the table so that the pins line up with
the previbusjbcatipn. This procedure in fact locates the line
joining the two locations on the map in the same direction as
the line exists in nature. Again from this new location jnap
in the desired features which can be conveniently sighted.
In this way the eritire_regipn to be mapped 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 Re used ih mapping featyre|_whlch
are not going to be used as plane table locations in the map-
ping process. This involves drawing a line In the. direction
IB
$f 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 1t_ Is imppsslbleto
avoid measuring the distances between plane table locations.
If a spirit level is available* 1t 1s 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
-frbotrt- six or e i g ht fee t l o ri g ~sh b U1 d be-markedroff in 1 richest *nd
the person holding the stick vertical ly 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 PROPfcRTIFS
The rocks that form the crust of the earth are divided into three
classes: '
Ighebus--rbcks"wh1ch are derived from the hot magma deepen the
earth. They include granlte arid other coarsely crystal line rocks *
dense igneous rocks such as occur in dikes arid sills, basal tj arid
other lava rocks, cinders* tuff* and other fragmental volcanic ma-
terials.
Sedimentary— rocks which cbrislst 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--cbriglooicrate* saridstbrie, siltstdrie, shale, limestone,
arid deposits of gypsum and salt.
Metam6rphic--rbcks which are derived frpm^bpth igneous^nd sedi-
Itientary rbcks through considerable alteration by heat and pres-
sureat great depths. They include gneiss* schist* quartzite,
slate, and marble.
Fig. 4 PLANE TABLE MAPPING
-10-
The pores 3 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 rah be stored in the
subsurface reservoir .of_the._fdck foraat1qns_1s large. The_mpst prp^__
ducttve aquifers* are deposits of clean, coarse sand and gravel : coarse
porous sands tones; cavernous limestones; and broken lava rock* Some
1 lines tones * however, arevery derise_ahd_uhprbduct1ye._ Hps t_of_the_ Ig-
neous and metamorphic rocks are hard, dense, and of low permeability.
They generally yield small quantities _bf water. Among the most unpro-
ductive-format i ons _ ar e ^tft e^i Hs~and 1?1 ays^ — The-openings" trr these ma"-
terials are too small to yield water, and tlie formations are structur-
ally too incoherent to maintain large openings under pressure. Com-
pact materials hear the surface* with open joints similar to crevices
in rock, may yield small amounts of water.
EXAMPLES OF MIXED ROCK
Medium sand with fine gravel, gray Fine gravel . . 2025
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%
Ttre nomenclature used in conso 1 1 da ted sed 1 men ta ry rocks 1s very similar
to that used for the unconsolidated rocks, the fotlowirTg^names should
be applied to the consolidated equivalent of the eight classes of un-
consolidated rocks.
" * . *•
Name of unconsolidated rock Name of consolidated equivalent
1. Boulders
2. Coarse gravel
3. Medium gravel
4. Fine gravel
5. Coarse sand
6. Medium sand
7. Fine sand
8. Clay ~
Boulder conglomerate
Coarse congfomrate
Medl urn cqngl omerate
Fine conglomerate
Coarse sands tone
Medium sandstone
Fine .sandstone
CI ays tone
* A formation, group of formations, or part of a fprmation that is
water belling.
TABLE 1
UNCONSOLIDATED MATERIALS
Classification
Grade Name
Particle Dimensions**
Very large boulders
ka rge_Duu i uers
Medium boulders
Small boulders
Large cobbles
2048 to 4096 80 to 160
lnba tn ?n£ft AC\ tn ftri
512 to 1024 20 to 40
256 to 512 10 to 20
128 to 256 5 to 10
64 to 128 2.5 to 5
32 to 64 1.3 to 2.5
GRAVEL
✓
Small cobbles
Very coarse pebbles
Coarse pebbles
Medium pebbles
16 to 32 .6 to 1.3
8 to 16 .3 to .6
_F1he pebbles
Very fine pebbles
4 to 8 .16 to .3
2 to 4 .08 to .16
SAND *
Very coarse sand
Coarse sand
1 to 2
.5 to 1
neuium sanu
-25 ta 5
Fine sand
Very fijje.sahd
Coarse silt
.125 to .25
.062 to .125
.031 to .062
CLAY AND
SILT
Medium silt
Fine silt
Very fine silt
Coarse clay
Medium clay
Fine clay
Very fine clay
.016 to .031
.008 to .016
.004 to .008 \
.002 to .004
.001 to .002
.0005 to .001
00024 to .0005
Name to be
Applied in
Logging a
Water Wells
Boulders
Coarse
Gravel
Medium
Gravel
Fine
Gravel
Coarse
Sand
Medium sand
Fine sand,
Clay
American Geological Institute Data Sheet No. 7
22
-12-.
Fig. S
NOMENCLATURE OF UNCONSOLIDATED ROCKS
!
) -----
, 5 Inches or greater
in diameter
■ ■■ '
i
i
i
i
»
1 3
MOULDERS
2 1/2 tp 5 inches
in diameter
COARSE GRAVEL
COARSE SAND
MEDIUM SAND
"7. . ■ i
.*""V." —
MEDIUM GRAVEL
FINE SAND
J —
Coarsest particles
barely visible
FINE GRAVEL
CLAY
-13-
I
Sedimentary rocks and volcanic rocks are sometimes Interbedded with
strata of volcanic ejecta. Some of ihese_strata have been deposited. *
by water and others by direct air fail. The terms "pumice" and "cin-
ders" should be used to describe these materials,.
Pumice A very light, excessively cellular ^volcanic glass A _ Its
color 1s -generally light gray or white and Is often so
light that It will float bh water.
Cinders Uncemented glassy and vesicular ejecta from a volcanic
€ ctme. Generally black or red in color. In logging a
well penetrating intdftrata of cinders, the cinders
should be also described by color and degrees of coarse-
ness.
MISCELLANEOUS TERMS RELATED TO SEDIMENTARY ROCKS:
Caliche
Chalk
A hard lime deposit generally found in the soil zone
in arld^reglons. It Isusually found in layers rang-
ing from a few inches to a few feci in thickness.
A soft, whitetg gray, fine-grained limestone. Often
incorrectly used on well logs to describe diatomite.
Diatdmite A sof* white to gray , fine-grained rock composed of
the siliceous shells of diatoms.
Dirt
Gumbo
Hard pan
Loess
Mud
Quicksand
A tgrffi used by many well drillers' to describe the soil
zone. The term "soil" with adescrf ptive adjective as
"gravelly soil" or "sandy soil" is recommended for use
bh well logs.
c
A term applied by some well drillers tg_a soft sticky
clay ? _ The term "soft sticky clay" Is preferred for
use on well logs.
A term that has been applied to many hard impermeable
rocks including glacial sill, caliche, conglomerate,
claystone, and sandstone. The term should never be
uspd on a well log.
Wind deposited material composed .chiefly _of_ijlt but
may contain subordinate amounts of very fine 3 sand and
clay.- Loess should generally be reported as clay on
a well log.
A- term used by many well drillers to defer 1b|__sOft __
clay or silt. The term "soft clay" 1s preferred for
use on well logs.
A term often applied to "running" or "heaving" sand.
The terms "finesand^ waterbearing" or medium s& rid*
waterbearing" is preferred for use on well logs.
)
Shale A laminated claystone. As laminations are not generally
discernible. In drill cuttings, the term "clays tone" 1s
preferred for use on well logs.
Slate A metamorphlc rpckpossesslng a very well developed platy
cleavagef The term has been used- by many wel^ drillers
to describe a "hard claystbheV It 1s recommended that
this term not be used to describe sedimentary rocks but .
restricted to true slates.
' POROSITY AND PERMEABILITY
Porosity is essentially the qapacity of a rbck or sedfmerit tb.cbntajri
water. It can be measured as the tptal volume of a rtwrterlar that 1s
void spacer Permeability is the capacity of a rock or sediment to
transmit water. Permeability is measurable as the quantity of water
fldwing through a given crbss-sectlprialareaper unit time. Permea-
bility isdlrectly proportional to grain siie^ Thus clay, which has
a high porosity, has a very l^fB^rmeabillty Bfccause 1t 1s fine
grained. '
The following figures indicate the pbrbstiy of common soils and rocks: ^
Saftd 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, scfilst, and gneiss 0.02* - 2%
Slate and shale 0.5 % - S% .
Limestone _ - 0.5 % - 17%
•
Clay ; * 44% - 47%
Topsoils > 37% - 65%
Silts may be ats high as_8p£ porosity In general, soils with fine,
separate particles, such as clay; to,>soil, and silt, have a very high
porbsity* In other words* they have a big* volume 1ri which water can ^
be stored. - ^
EVALUATION 0F SOURCES ' s (
THE QUALITY OF WATER,
Absolytelypure water Is never found in nature. The Impurities in water
vary from dissolved gases and chemlal compounds to suspended ^tter
such as disease organisms arid dirt, *h1le some of these Impurities
can be seen by the naked eye and others can be detected by taste or odor,
most can be detected only by laborato y test, '
Water takes on various characteristics a<nd properties as It passes
over arid through the earth. These characteristics and properties
vary, and are dependent on the /materials Ihcouritered. They may be N
classified according to means of detection as physical (detected by
• one or more of, the five senses) and chemical (detected by chemical
.analysis). The _mpst^1mpprtant_phys1ca^ are turbidity*
^color, odor, taste and temperature. The most Important chemical char-
acteristics are acidity; alkalinity* hardness, and corroslveness.
Sometimes these two v tyges_ of character istlcs overlap; for example* iron
In water Is a dissolved mineral detectable by chemical analyilSj 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 pfeco-
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
1n specific, quantitative values. For Instance, the bac^iolpglcal
quality of filtered, chlorinatedwater is dependent upgn the bacterial
content of the raw water; ,its chlorine demand; the coagulating, settling
and filtering characteristics of the _treatment_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 signi-
ficance of the degree of bacterial pollution of raw water, and henc^
of any bacteria remaining in the treated water produced., depends .upofi
the probable source of cohtami nation of the raw water with coliform '
organisms, which serve as anicdlcator of pollution. These organisms
may have originated largely from surface drainage, a situation likely
to be most noticeable when manured .fields are found within the watershed
involved. On the other hand, sewage pollution may be the chief source
of such organisms, in which case the incidence of intestinal diseases
among the population contributing the sewage would have ammarked impact
on the watery In this case the probable ratio between_the numbers of
pathogenic organisms and of coliform bacteria in the polluted wajter'
will be considerably increased. Such conditions are often encountered'
in rural as well as *sem1 -urban areas where_intest1naj diseases constitute
a serious public health probl em ? the i treatment "df. the sewage is pot prac-
ticable, and effective water-treatment 1s beyond the economic and tech-
nical resources available.
For these reasons, ariy .bacteriological standards of quality adopted
for drinking-water on a country-wi^e basis* generally, appear to be
too rigid for large areas where, because of economic and social con- .
dltidns, theyarempltd
must be reckoned that the adoption under these circumstances of more " *
lenient standards - f betause they a^ear to be morp-^seajjstic^ only
cpnfuse_th£ issue bj lowering the goal of safet^and g^blllty wlthput
prQviding a meaningful substitute. Instead, it is preferable to keep
the pubTlc health objective; of the water supply constantly in mind*
-16-
but to appraise local situations and review pertinent Information 1n
the light of qualified professional Judgement. In^many cases i there-
fore H II belt 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 hot 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 1t possible to
provide consumers with ample quantities of water 1n their own homes,
thus fulfilling most of the major health objectives of the systems.
In some Instances this 1s 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 1n the right direction, and 1s
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
gradually bring about the' Improvement of pSaht efficiency, operation
and technical supervision to a point where the enforcement of existing \
standards of water quality may be possible.
It 1s necessary and desirable to establish some form°of control over
rural water-supplies. However, 1n 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 latterj the attention o# the local health adm1n-_
i strati on should be concentrated primarlj^on those major elements of
location and design of the supplies whlrfT will afford natural protec-
tion later against- outside cohtaffifnlrfTon, 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 jnade for the purpose of-detecting major health hazards.
Bacteriological Standards for Drinking Water Recommended by the
- WHO Study Group
Some public dr1nk1ng"£ater supplies are chlorinated or otherwise '
disinfected befora being dlstribated; others are not, ..Effective,
chlorlnatlon yields « water which 1s virtually free from conform
orqanlsms i.e. these organisms are absent 1n 100-ml portions;
if communal supplies .?hich 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 chlori nation or disinfection! or other treat-
* . ment, of these supplies. _
A standard demanding that col 1 form organisms be absent from each
100-ml sample of water entering the distribution system--whether
the water be disinfected or naturally pure— and from at least ?ox
of the samples taken from the distribution system can be, applied
27
(J >:
-17-
In many parts of _the_world. Although there 1s 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 1s hot 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 aretreated or. disin-
fected and for those which are hot treated... The-_fd]low.1ng._bac-_
teriolpgical standards_are_recomm^
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 wi]] be taken. . . For each individual
sample, co Inform density Is estimated in terms of the "most
probable number (MPN)" in 100-ml of water, or "MPN" Index...
The use of the MPN index Is recpfrtnended 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 us|_ of _data from aseries of samples to warrant
its use in the recommended standards.
Treated Water
Si 90% of the samples examined throughout any year, coliform
bacteria shall not be detected or the_MPN_inclex 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-ml portions of a sample this
would preclude three qf_the_five 10-ml portions ( an Mp N index of
9.2) being positive in consecutive samples.
In any instance in which two consectuive samples show an MPN
index of coliform bacteria inexcess of 8, an additional sample
or samples from the same sampl1hg_ppiht_shquld_be_exa^^
put delay. This is_the minimum action that should be taken.
It may also be desirable to examine samples from several points
in the distribution systeiii_ahd_ tt_SUpplemnt_tKe$$_9lth_sai^les
col lected.f ram sources, reservoirs, pumping stations and treat-
ment points. In addition, the operation or all treatment pro-
cesses should be investigated Immediately.
Untreated Water
In 90% of jthe samples examined throughout any year, the MPN index
of coliform micro-organisms should be less than 10. None of the
samples should show ah MPN index greater than 20.
An MPN Index of 15 or more should not be permitted 1n consecutive
samples. With the examl nation of five 10-ml portfbns of a sample,
28
-18-
this would preclude four df_ the five jO-ml portions (an MPN index
of 16) being positive in consecutive samples* If the MPS Index ^
is consistently 20 or greater § application of treatment to the
water-supply should be considered.
In any Instance in which two consecutive samp] |s shpw an MPN Index
of conform organisms greater_than 10; an additional sample or
samples from the same sampling point should be examined 1mmed1-_
ately. It may also be desirable to examine samples from several
points in the /distribution system_and to supplement these wi th
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 all possible
points, of pollution, are available and Indicate that ihdices hlgh-
er than the established max1mum_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
Watlr/of gddd chemical I 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 whdhas 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 charactlristlc of
being pleasing to the sensf 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 i used in Judg1hg_these_gual1t1es.
They are the senses of sight (color and turbidity), taste, smell (odor),
and touch (temperature). However, palatable water is hot always safe
to drink or potable.
Jurbidity and color are important in rural water-supplies. Depending
upon the character of the watershed * turbidity may yary/cdhsiderably_
from one season to Stidther because of rainf all . A sudden increase in
turbidity may do. serious damage, or at least stop the operation^ of
small water-treatment. pi ants if adequate precautions, are hdt_taken In
advance in order to. al 1 Bw_fdr_ reject 1on_of_the_ incoming supplies at
such_ times. Water "from slow-moving streams and sma'M lakes is likely
to be colored, at least during certain seasons of theyear. Both tur-
bidity and color will cause discoloration of clothes and may be respon-
slblefpr 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
... O
ERIC
-19-
destroys storage tanks built bf_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 well 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 _pipe|j_thUs crea-
ting increasing difficulties with maintenance and operation of a water
system. Various materials, mostly bituminous compounds and cement
are qsed by manufacturers for lining the Interior sUrfacfs 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 will dissolve carbonates from
rocks in the ground, thus producing soluble bicarbbriates. Depending
upon the relationships between the bicarbonate alkalinity and the pH
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 som times develop sufficiently to become
3 L_th1ck_scale which obstructs fmall 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^ 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 small rural water-supply systems arid* 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, dissolve and_ 1 eaves - % and to humus
and iron and 'manganese salts, true color is due to substances in Vcxi*
solution; apparent color includes true color and also that due to sub-
stances in_suspensipn. Water taken i f rom swamps, _weedy_ lakes* arid
streams containing vegetation is most likely to be colored. Color may
also be causejd by industrial waste* and turbidity. The latter is re-
sponsible fori an _apparerit_cpl or/ rather than i the true_co]prj_arid_1s
caused by materials of vegetable origin. Color as such is harmless,
30
but objectionable due to its appearance arid to the taste and odors
sometimes associated with it.
ODORS AND TASTE
Taste and odors found 1n>water are most commonly caused by alga (m1n-.
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. Qnjhe.
other hand, palatability is frequently affected, particular y when a
substance such as bone or fish oil 1s 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
Warn, water tastes flat, towering the tem P e rt tur ^ 0 ^?^ v SUp ?: e ?hp S
odors and tastes and, therefore, increases its palatability. in the
summer the temperature of deep lakes and reservoirs d " re "« 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. Cool 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 "use water to behave as
either an acid or as a base. The degree of acid behav or is called
acidity. The doqree of basic behavior is called alkalinity ^ince
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
" waler. The pH value ranges from 0-14. A value of 7 is neutral.
A high pH 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 is caused by the soluble salts of calcium, ma ^«i urn. Iron,
manganese sodium, sulfates, chlorides, and nitrates, ^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.
31
-21-
The hardness caused by carbonates arid bicarbonates is called carbonate
hardrifss. Jhe_ hardness caused by all others (chl prides t sulfates,
filtrates) isca 11 ed non-carbonate hardness. Alk^ Is usual ly
equivalent to the carbonate hardness. Sodium, however, also causes
alkalinity*. In natural waters, sodium is not normally present 1h
appreciable amounts. Therefore, in natural waters, the alkalinity
is equal to the carbpnate hardness. . After a water has been softened,
however, a large amount of sodium remains in the treated water. In
softenedwater, the total alkalinity ts the sum of the carbonate 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 a lka 11 nity and
carbonate hardness of water. Calcium bicarbonate when
heated produces carbon dioxide and calcium. carbonate.
This calcium carbonatp precipitates as scale in boilers
and distillation units.
Calcium sulfate or gypsum. Causes noncarbonate hardness
in water. Being more soluble in cole! Water than in hot, it
separates from the water in boilers and forms scale on the
Doi ler tubes. -
Calcium chloride. Causes noncarbonate hardness in water.
In steam bpilers and d]\stjllatipn_uni ts, 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 hydrolpgic 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, _arid_disease_
organisms. As it enters theearth through seepage and infiltration
of the suspended impurities may be filtered out, but at the same timei
other minerals and chemicals are dissolved and carried along. It is now
ground water in an underground deposit and, although it may now become
lei-s cpntaminated 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.
/
-22-
Impuritles Iriwater are__|1_ther_suspended or dissolved !., The suspended
Impurities are usually more dangerous to healthy. They Include mineral,
matter, disease organisms* silt* bacteria, aridalgae, arid must be des-
troyed 6r 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 arid rocks.
B) Character of vegetation; forests; cultivated and irrigated
lands, including salinity* effect on Irrigation water, etc.
C) Methods of sewage ^disposal whether by diversion from watershed
or by treatment.
bj Character and efficiency of sewage-treatment works on watershed.
E) Proximity of sources of faecal pollution to Intake of water
supply.
TURBIDITY TEST
The turbidity test is used to show the amount of suspended mattef_pres-
ent in raw water* arid alsb_td 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 using
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 cap 1s 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
LESS THAN 5 ppm
DOT HAZY
BETWEEN 5 ppm AND 1W
DOT OBSCURED
MORE THAN 100 ppm
Fig. 6 Turbidity Test
... 33
o " '•■
ERIC
-23-
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 f 1 vers , ponds and lakes* and
the small upland streams which_may originate from springs antf collect the_
fun-off from the watersheds. The quantity of ruh-bff depends upon a large
number of factors, the most impprtant pf whlch are the amount and Intensity
of rainfall, the. climate and vegetation and, also, the geplpgicaij_geog-_
faphlcal, and topographical features of the area under consideration. It
varies widely, from about 20X_in afld and sanSy areas^wheroTtS^falfvfall
Is heavy. Of the remaining portion of the rainfall I, somepf the water
percolates into the ground,, and the rest is lost by evaporation, trans-
piration and absorption.
a -
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.
bj 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 perl pd
are low, and ground-w^ter tables are at minimum elevations^
2. „. Eor_purposes of ^^^estimatf^" gi^tTtles of stored water which
would sustain demands during these critical periods.
The peak demand rates must be estimated In order to detemlne plumbing
and pipe sizing, pressure losses, and storage requirements necessary
to supply sufffcieht water during peribds of peak wa^er demand.
-24-
SURFACE WATERS
* Surface water sources are lakes and ponds, rivers, streams, and control
led catchments (cisterns). ;
takes arid Porids^
A lake or pond 1s any. standing tody of Inland water.
Quantity: Advantageous in that 1t 1s usually able to store
water in wet periods for use 1n dry periods.
Quality: Generally poor. Normally turbidity and bacteria are
the major pollutants. Use only when ground water sources
and control led catchments are not available or are Insuf-
ficient or Inadequate.
Development requirements:— The^ Weal- tuition U that the water-
shed permits water of the highest qual 1 ty tcTFriter 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 1f necessary).
Treatment requirements: No lake or pond water can be considered
safe until 1t 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 e ^] v e treatment
and a floating intake. structure. In many cases the ™ Ration
unit becomes clogged and must be cleaned. It 1s advisable to look
elsewhere for a source of Water.
Rive rs and St reams
General- A stream or river 1s a body of running water on the sur-
face of the earth, from higher to lower ground.
n.ianHtv Ylpld controlled by rate of minimum flow per day and
° year. Streams qerikr-aliy exhibit marked seasonal variation In
flow.
c 35
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-25-
Quality:^ General lyppor. Chemical nature partially dependent
on bedrock, fthyslcal and bacterlologlcalqaallty highly
variable. Easily contaminated. Impossible to exert saril-
; tary control ovfc^watershed. - *
development requirements: Requires-a submerg^ Thtake structure
arid 1n the case of small streams requires the construction
of small diversion dams.
Treatment requirements: Same as lakes and ponds. _L1kejy_to be
more turbid and have a greater quantity of chem.ical pollu-
tants.
Treatment Processes: Same as the lakes and ponds.
Warning: Rivers arid streams shqulO
tial source of water unless, of course, adequate treatment
facilities already exist.
Springs
J3eheral: The outflow of water that has previous ly_run or per-.
" ro^^d^Ju^Jj^ Two types:
1. Gravity-ground water flows over 1mpifvT^T^tl^tum-onto^
ground surface.
2. Artesian-water rise to surface after confinement between
two Impervious beds.
Quantity: (1) Yield of gravity |pf 1ngs_fluctuates_w1th 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*- fpMrigs emerging from! imestone,
channel s all ow for very 1 ittl e -na-tura 1-f 1 1 tra ti on . May become
highly turbid and I polluted after heavy rains. Careful Inves-
tigation recommended.
Development requirements^ El imlnatibn of all Iburces of contami-
nation hear point of emergence. If gravity type, further
development not recommended.
Requirements--- (1) filtratlbh-sdmetimes not necessary
(2) disinfection
Processes: (1) slow-sand filter \z) chl or 1 nation
« Gravity springs have the advantage in that they proyidfa
gravity type distribution syfternv JKflltration and storage
unit can be constructed before- poi nt of v emergence. Such a
development is not feasible unless the spring has a substan-
tial yield.
-26-
Catch Basins (C teteffis^
General! A- sloping surface^area for_cpliect1dri. of ralnfa
*?ff_iw'diw_to,«_cofe«d 'tank (cistern). * Roofs are the most
common cal lection' areas. 1
- . . y _ . v
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: Whol 1y dependent on the character of the surface of the
area of collection.
Development requirements: Construction of a watertight, mahholed
covered, tank with* outlet.
Treatment requirements: Tank roust be periodically disinfected.
With fenced catch areas of clay surface, filtrationadylsable
bifdfe_ intake. W1th_ roof secernent or other hard surfaces
It is advisable to- have some screen to catch leaves, etc.
Hard surfaces should be cleaned periodically.
Treatment processed: Disinfection is the only necessary treatment.
GROUND RATER
Ground water serves the great majority of people who live in rural areas
Tddrh^^^watfrFs^ system of one type or another. The reason is
that, among the^varTous--^ far the
most practical and safe in nature^ E^mnHtH-a-J^
country such as the USA, jnunicipal ground-water 1n?taTlTtitms^far_qut^^
number sarf ace-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 cdntpunlties 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 1t 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 1n mineral content;
2. It usually requires pumping.
-27-
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, 1ri order to reduce transport costs;
2. to extract, It fey fneans of a system which producesthe quantity re-
quired, safeguards the quality, and, at the same time, Involves the
least capital outlay;
3. to transport the water to theconsumerln a way which requires the
/least amount of operational and maintenance skill and cost.
- Area* where there are food possibilities of obtaining water from infiltration faiitries, well-point
2 --~Gro!mt^^ that a flowing spring S formed. At the foot of river
_ banks and hill, other spHn^mayi>ossM>lx^4ouhd.
3 m Top of (round-water table
4_ — Area of infiltration to supply-formation B
A ~ Non-confined (non-artesian), water-bearing formation covered with top soil
8 •*> Confined (artesian): water-bearing formation
C — Impervious rock, or hard-pan formation
2'
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 fpraattpns) (See Fig. 8). These
ran 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. F1g. shows
the occurrence and distribution of subsurface water.
-28-
F1g. 8 OCCURRENCE AND DISTRIBUTION OF ^UB-SURFACE WATER
SOIL WATER
Limited to tbc Mil irvj mcb«l
by ruuli
H
7ZCC
—
§3
PKLUCCLAJttWATES.
Adhere* to r»*k turface*
throughout inn* *4 aera*
tbn tod ii >»ot movni by
gravity bjl may be
•ltae.tr J _ _ by__ evap»»r»l ion
and lraiuf*f Jliun
CRAVITV-Olt A AB03E
WATER
Movr« down* jnl by force
«»'___ iraw.y tVuvtlwut
inn*
PERCHED WATER
Occur* torttty in »he tone
»bove'fth iaaperviouJ bar-
rier
CAPILLARY WATER
OoWo -owly-i^-lbe- eafliUary
fringc il Ibe bolloo of the *mo
Fit EE WATER
jn_d b bounded by the firal ef-.
fectW* cuitfiiuhg stratum
MoVfNG 6£TWf£# SUMS 6* WMt* -.-
BC « preuur* iraditnt: indicates actual itttic lave! in walls plarcinf U»i conduit
Reproduce I fro- Tolman, C. F. (IM7) GroW p. 5* by kiM permbMO* of MeGuwHill Book Co.
Inc., New York
39
BEST COPY WM^BLE
ERIC
-29-
The great majority of wells for rural water-suppl iestake water from
the "free-wa.ter zbhe\ (Figs. 9, 101- These will usually be jetted,
dug* dMverij.or bored wells. Infiltration galleries also take water
from this zone. Drilled wells often penetrate* the confined water
aquifer. It 1s from this stratum that flowing wells are developed. *
Ihi aquifer must be supplied with an ample quantity of waterlf _it_is_
to serve as a source. It is simply a reservoir and can b^depleted in
the sanie manner as a surface reservoir if its supplyis inferior to the
demand placed on^it. 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_cppiun1t1es.^ An element of greater sig-
nificance fpr_the_engineer searching for ground water pertains to the
characteristics of the soil formation of the aquife* M 1 .e A ,_tq the_abil-
ity of the aquifer to give up water and, therefore, to serve as a re-
liable source of supply. z
The quantity of water that can be extracted from an aquifer will depend
on (1) its porosity and permeability, and (2) the draw-down 1n the '
weil._ The porosity and the permeability, of a formation a*e_ limited _
by nature; aptf while conditions may be altered somewhat in the Immediate
vicinity of a well intake, _the_general nature of the aquifer is fixed
and cannot bVnrodified. The draw-down in a well, however, can be varied
within the limits of the thickness of the aquifer, the penetration of
the well 1htb thi aquifer, and the capacity of the pump used (F1g. 9 »10 J.
Ground formations* however, have S certain. tehdency_tp hold the wat§r
and *o give up only a part of it. This characteristic of a soil for-
mation 1s called permeability; it is the quality of a formation which
controls the passage of water throu^_ it.__From_a knowledge of hydrau-
lics; 1t 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
permeabilltyjvery small opening between particles), so that_water___
passes through them with great difficulty. Gravels and sands, on the
other hand, are permeableahd therefore allow ground water to pass with
relative ease.. This type of formation is^also porous, as can_be_ieen
above, so that it can store larqe quantities of _water. These, then,
are the water-bearing forma ti oris _mp|t amenable to the development of -
wel l I and most Important to the engineer in searching for a fural_cqm-
munity water-supply. Sandstone 1s both_pprQUs_and_perv1ous and there-
fore an excellent aquifer which canbe tapped to produce-large Quanti-
ties of water, especially if it Is confinedas shown in F1g A ?_Ifqr-__
mation B) and Fig. 10 . Where 1t 1s known, for example, that sandstone
underlies an areaj and whe^_no other_read1ly available source is found f
a telt hole Into this stratum would be a" good risk. _Chal_k_fdfmat1ons
in the British Isles and in Haiti are known to produce reasonable
quantities of water. '
ERLC
BEST COPY AVAILABLE
39
30-
A «• Ground surface
B - Top layers of soil
C = Water-bearing stratum
D Impervious stratum
E - Thickness of water-bearing
_ stratum
F -. Water table
G « Draw-down
H -« Depth of penetration of well
into aquifer
J » Draw-down cone
J_ « Curve of maximum draw-down
P Pump
R » Radius of circle of Influence
Fig. 10 WELL TAPPING CONFINED WATER
P
A_
■A
A ■» Ground surface .
C w Water- bearing it rat urn
P ■ ln|pJtr>ioui_|trAturn
E — Thickness of water-bearing
stratum
I s - Water t'ble
C mm Drawdown
I. ■» Drawdown cone
P_ *! £ump_
Q ^iPe_p_th of witer In weU
R **( Radius of circle of influence
41
BEST CQPy AWFLABLE
-31-
Exceptfpr 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
ruVe^ 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. _Irt_this_way,_samp]es of the be_
taken and examined to fletermine the characteristics of the aquifer and
its ability to supply the quantity of water /needed. Fortunately, a_
great many small towns jn
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, qalleries, 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 paragraphs.
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 recbnnbitened for a source requiring
less development. L __A11 intake hoses pr 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 unnecessarily pollute them. Proper anchorage of suction
lines and strainers prevents loss of prime* punctured or kinked lines,
and damage to strainer. _Figuf|s_ll,12il3 an<J 14 depict several of the
common methods of suction inlet anchorage.
Waterat the 'intake point should be as possible. The
straineron the suction hose is placed at least 4 .inches below the water
level . This precaution reduces thepbsslbili
clogged with floating debris, or the prime being lost due to air getting
into the suction line.
SURFACE WATER SUPPLIES
Advantage s . For normal field water supply, surface water is the
most, accessible type of water source. This source also lends itself
readily t£_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 ^taJces. 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_oyerhead to pre-
vent the suction of air into the_intake pipe. If the water source
is a small stream or shallow lake the Intake pipe can be secured
to a post or pile as shown in Fig. 11 .
Pits. When a stream-is so shallow that the intake screen i 1s_nbt__
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
gravel to prevent dirt from ehteringthe purification equipment ,
(Fiq. 12 _L The, screen is surrounded by gratfcl which prevents col-
lapse of the sides of the pit^ahd also shields, thv?_fcreen from dam-
age by large floating objects^ The graver 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 .
Darns^. the leveH of the water in small streams can be_ raised to *
cover the intake straiher by buildlng a dam as shown in Fig. 14 .
In swiftly flowinq streams, a wing or baffle dam can be construc-
ted to protect the intake screen without impounding the water*
(Fig. 15 ).
Floats. Floats made of lbgSilumberj sealed I cans, or empty fuel
drums can beused to support the intake strainer in deep-water. _
They are especially useful in large streams wherethequality of
the water varies across its width or where the water ts not deep
enough near the banks to cover the intake strainer. The Intake
point can be covered by ah adequate depthpf_water byjarichoring
or stationing theflpat at the deep part^of-thie 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
tb_secufe theflpat to the banks, the position of the float _cah be
altered to correspond to changes In depth by manipulation bf_the
liheo. The chief advantage bf_a fVpatintake is the ease with *
which the screen can be adjusted vertically. Fig. 15 illustrates
two types of improvised floats. \
8 _______
Galleries. Water- from muddy streams can be improved in quality by_
digging intake galleriel along the bank. __A trench is dug along the
bahkjdeep enpugh so that water from the stream percolates into it
so It- intercepts ground water flowing toward the .stream. _ The trench
is filled with graveltb preventthe sides from collapsing. The in-^
take strainer is placed in the gravel below the water line tFig. 17 J.
The amount of work required toprbduce thegallery is justified by
areductibninthe amount of chemicals needed to coagulate the water*
the elimination of the necessity of frequently backwashirig the filter
and the higher quality of water obtained.
Drive Points. Many times it 11 advantageous to utilize shallow ground
water. sources or percolated waters adjacent_to a turbid surface water.
Hell points are Issued in 2-inch diameter, 54-1 rich lerigths. A drive
43
\
^33-
Flg. 11 Direct Intake* with Hose oh bottom of water source
FINE GRAVEL AND SAND . . " * " ■' •
o_._ _ _ _ _ _
Fig. 12 Surface Intake with Hose burled 1n gravel -filled pit.
-i .
-34-
TO UNIT-
4"
WATER LEVEL
GRAVEL
FINE GRAVEL AND SAND • .o • •
INTAKE SCREEN
Fig. 13 Use of bucket on end of surface Intake
PICKETS
WISED
TOGETHER
4_T0_1 SLOPE
FRONT AND REAR
*^^rT^* ^ i CORRUGATED IRON
WOOD OR**- — J$
ANGLE IRON
PICKETS
SAND3AGS FILLED WITH MUD -
7
Fig. 14 Improvised dam for Impounding siMU^feams.
4S
Fig. 15 Baffle dam for protecting inlet strainer.
INTAKE SCREEN ,
Fig. 16 Float-type surface, intake, with anchors.
ERIC
-36-
GALLERY FILLED WITH GRAVEL
F1g\ 17 Gravel-filled gallery Intake..
LEAD-OFF DITCH
Fig. 18 Spring Inlet.
, 47 .. . . ... . . . ^
ERIC
•37-
cap is driven Into the ground with a sledge. Successive sections
of pipe* each 5_feet Iphg^ 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. 1 I if t of the pumps_ issued
with, field equipment is 22 to 25 feet at sea levels Suction lift
pumps can be used, therefore, only where the pumping level in the
wellwill be within the limit of suctionTift, or 22 to_25 feet be-
low the position of the pump. ; At 5*000 feet ?bove_ sea level j the
practical limit of suction li/t is only 20 feet. It should be noted
that since a suction-lift pump i must create a partial yacuutn In th?, ^
suction line, it is necessary that the line be absolutely airtight
if the pump is to function properly.
SPRINGS
Springs yielding 20 gallons per minute or more of water can be used as
a source of field water supply if properly developed. Springs may be
developed by enlarging the outlet of the spring* and by reducing loss
by dammina and conductina water to storage. To reduce possible pol-
lution, springs should be cleared of all debris, undergrowth, top soil,
loose rocks, and sand.
Water which flows fromrocfcs under the force of gravity and collects™
depressions can be collected in boxes or basins i pf wopd^ til e A 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 pol lytic n. This re-
quires fencing off the areaand providing proper drainage. Flg^
shows a spring inletwhich has been protected in this manner. The
screen on the overflow pipe prevents the entrance of insects andsmall
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 spring located pna 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.
2. Constructing pipeline tunnels from the spring. to the collecting
point. Pipe of large diameter is more suitable for thispurppse.
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
sprlngthan blasting. In using explosives 1r developing the yield
from springs you should ixercise great caution. Blasting 1n unconsoli-
dated rock ^ may shift the sand or gravel in such a way as to divert the
spring to a different point;
' . t 48
ERIC
-38-
-39-
Fig. 20 FinisheG drive point well.
59
-40-
WELLS
When ground and surface water suppl'1 es are Inadequate or cannot,be iised .
ground water supplies are developed by constructing wells ^el^s ^re-
classified Into five types, according to their method of construction.
These are dug, bored, driven, jetted and drilled wells. Each type of
well his 1ts 9 part1cuiar advantages, which may be ease of construct on,
type of equipment required, storage capacity, ease of Pen et ™^° n n J?t°
certain types of formations, or ease of safeguarding against pollution.
THE BASIC REQUIREMENTS jjg A WATER SUPPLY
The objectives of any water supply, big or small, are to P™vide 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 1s essential. Water which the tests have shown to be safe
\ may be polluted after the samples have been taken and the onlj wwf-of_
ensuring the early detection of intermittent pollution is through f re-
cent routine bacteriological examinations. In ruraTareas H ^often
difficult enough to have one such examination done but to Insist orL
weekly repetitions would be quite unrealistic. The Bacillus coll which
normalities in the bowels of warm-blooded animals and which Is pre-
sent in human faeces in enormous numbers 1s used as the bacterial in
dicator. of pollution. Unfortunately there is no ready method of dif-
ferentiating B. col i of animal origin from those of human origin.
In view of the foregoing 1t is of the utmost Importance that the supply
system be correctly located and constructed so as to provide natural
detection against outside contamination. A careful ^ inspection of the
?e°rt?nen? arS must, therefore, be carried out and it i^ld beregagd
at regular intervals to ensure that this area 1s maintained In the neces
sary sanitary state.
ADEQUATE QUANTITY \ ~
The average amount of water required dally by an individual Is about
Ona lions for domestic purposes, I.e. drinking, coofeing, bathing and
aundry! Piopli can SwItE less for short periods «hen jecessary. but
public health is best served by encouraging the use of water and^dls-
couraainq its waste. T» provision of 25 or more gallons per person
Jerdly does no? include water needed for gardening purposes or for
\
\
-41-
The former usually affects only the bungalows and varies considerably
in amount. The standard daily allowances for animal sare : --for horses
and cattle--10 gallons per capita: and for sheep, goats and" pigs, 2 gal-
lons each. J^ospltalsrequire about 50 gal Ions jper patient dally , and
schools need approximately 10 gallons daily for each chllcU
AVAILABILITY
a 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 tap! and
the wastage of water is minimal , On the otherhand, where the dlstrl-
- but ion of water is by public stand-pipes , the ta^ps" are generally left
running and many of them are repeatedly broken so that they cannot be
turned off ^ Unfortunately the capital cost of a waterpbirit in each
house is often too great and It 1s 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 arid they will continue
to use their bid polluted sources unless the news^nitary supply 1s
superior in some respects obvious to them, such as greater convenience
or greater reliability. They may bathe^tfiemselves 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 riot 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 pollutedwater. Such prac-
tices defeat the real object for which. the new supply 1s, being instal-
led, namely, to improve the public health. As many stand-pipesamL
household connections as possible should, therefore, be supplied and
the layout of the whole. pipe system should be such as to facilitate the
futjre provision of a tip 1n each house. The following are Suggested
as minimum standards:--one standrplpe should not serve much more than
40 people; arid in the case of wells to which the people must no for their
water there shbuld be at least one well for every 250 people (approxi-
mately) . ^_ .
SELECTION OF THE SOURCE OF SUPPLY
* •*
The choice of a source of supply for development depends on a number of factors i
chief among which are: --the quantity and ouality of the water available; the
possibilities of sanitary control of the catchment area; whether the water
can be supplied to the consumers by 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 1 .
The first step in*startinn any water scheme is to determine whajt source
of }supply are available. ' Frequently a good source is not difficult to
find but it is usually advisable to check all alternatives asiqme may
be more economical apid safer to develop^ Sometimes suitable sources
are not obvious and a serrch should then be m^de in the valleys, albrig^ ^
the foot of the hills* when?- the vegetation Is greener » arid such places.
In this rlcbnnaissance theinhabitants are generally very willing to
assist with their 1 oca 1 knowledge. *
If the search falls to^reveal a satisfactory source an investigationof
the groundwater becomes necessary* and for this a knowledge of the_ lo-
cal geological font»t1dns_1|_mpst helpful. Study of any existing wells
villi provide some Information about the layers 1t penetrates, and the
location^ quantityahd quality of the water. Unless a good deal 1s__
already known about the aquifer It Is expedient to sink test holesat
various liktely spots. These holes may be made with a pipe^ abbut v 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 surf ace. __If It Isnecfssiry to probe |ny_deeper,1jt. 1s
usually wise to obtain the services of an engineer possessing the ex-
perience and the equipment for this type of Worfc._ 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
rainfal I f iguresmay be obtained and the history of springs and exist-
ing veils 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- of ten neglected.. Animal contamina-
tion of the water is very undesirable* and_in_sbme_places may be danger-
bus, but thegreatest hazard lies In pollution from human source*. It
may be possible to finda spring, or stream, coming from a safe catch-
ment area situated uphill frqm.humah habita
cable to render a^source safe by moving potential origins cf cbhtami na-
tion or to protect the source by suitable intercepting drainage etc. °
Though the water frbm a ltream may be liable to pollution it 1s often
feasible to obtain wholesome water through wfel Is and infiltration ,
channels sunk in sand and gravel layers near, the stream. Wherever -
pblslble the watef 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 require! jrp_t^ bacteriological physical,
and chemical requirements and which can be delivered to the consumer
by a gravity system should be given f irst cqjislderatlon. This
would usually bf linjlied to spHngs and protected drainage areas.
Such a system requires no treatment and no pumping and* therefore,
53
1s_ ideal from the_ppint of view of itialntenance, which is thus
reduced to an absolute rtinimurg.
Second-priority Consideration
Water which requires no treatment to meet bacteriological - t physical
and chemical requirements bi^t which must be pumped to consumers,
would be the second choice. vWell supplies would fall within this
category. - . \
Piimpihg can be ah economical and simple solution, but it can also
bean expeh|iye and complicated* one, according, to Ipca^^
stances. It depends on the availability of qualified operators*
and bh the local cost of fuel. Such factors vary widely from
country to county 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 ^hich requires simple treatment before it can meet bacterio-
logical, physical ,_pr chemic|l_requirem^ j can be del 1-
vered to the consumer through a gravity system should be given 6
third-priority consideration. Simple treatment is considered. to _ __
be limited tO| (1) stprage which would provide plain sedimentation
and some reduction" in bacteria, (2) chloririatjbh without the use
of a mechanically operated chloririator* (3). slow sand filtration;
or a combination of "these.
For rural areas thisis normal ly an Inferior solution; It Is usu-
ally more expensive than the above solutions and involves bpera-
/ tibhtl procedures which are mostdifficult tb_ma1htl1h_1ri_small_
rural communities. In such places, when the^chlorine stock runs
but, chlbrihat.ion is abandohedin almost, every .instance; and, when
the illow sand fjltlr becomes clpggedj a L^^s|_4'sLofteiLCQns1dered
an easy arrangement. Such is the history of treatment measures
in r.ost rural* areas where routine technical assistance is hot 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 £y^ pumping w$uld obviously
be the most expensive choice to make,
DETERMINING IMF RELATIVE COST OF A DEVELOPMENT
The easiest method of determining the relative cost of a development
Is to:
(A) Estimate the cost of the various components for a given design;
(B) Calculate the time required for construction; ____ •_
(C) Determine the total labor cost from the price per hour;
(D) Sum items A and C.
WATER SUPPLY SOURCES
LESSON NO. 1
LESSON OBJECTIVE-
Describe the methods used to locate and record
. . _ . . i _
existing water supply sources with respect to
the community to be served.
TOPIC
Topographic
Contouring
Topographic
Mapping
Plane Table
Mapping
INSTRUCTIONAL PROCEDURE
Hand out exercise on topographic contouring
and assist students where necessary.
Disouas, the use of the compass mid the
interpretation of topographic maps.
Demonstrate drawing a cinjde topographic map
of a prominent topographic feature.
Outline what features are to be included and
how they are to be represented in a topo-
graphic sketch map.
Assign students to groups of five. Rave each
group map a Quarter mile area. Escsh map
should include the following features:
1) man-made structures
2) livestock grazing areas
3) ¥^®?_? u PP^y sources
4) disposal systems
Demonstrate how to construct a more service-
able map, the plane table map.
SUPPLEMENTAL MATERIALS
RELATED REA DING -
Manual of Field CJeologj
p. 21-25. __ L
Any basic 1/iboratory
manual of Physical Gebld
Manual, of Field
p. 3&-50.
A.F.M. _TM 5-700
p. 6-15.
55
-45-
WATER SUPPLY SOURCES
LESSON NO. 2
LESSON OBJECTIVE* Demonstrate how to identify and evaluate various
water supply sources •
topic
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS /
_ RELATED READING
Rock and Soil
Type
Outline the physical characteristics and
discuss the hydrological properties of the
basic rock ajnd soil types.
Assist students in identifying the basic rock
and soil types>
Have each student identify rock and soil
types from a series of circulating samples.
rhysical and
Chemical
Pollutants
i _ . _
List the ma^or chemical and physical pollu-
tants and discuss the nature of these
. pollutants.
Manual of Individual
Water. Supply Systems
p. 5-13.
Identification of
rhysical
pollutants
Demonstrate how to identify turbidity with
the measuring cup.
AccH fit, ^-turfpnts in identifying physical
pollutants from a suite of water samples .
Water sp^ples* chould reflect the various
pollutants: turbidity - 9 color, odor, taste
and temperature,
\ ' \
Outline the factors that influence the
*
Water Supply
Sources
Manual of Individual
quality and quantity of a given water supply
source .
Water Supply Systems
p. 13-20 \
List\ tfid discuss the characteristics of the
vni'loijs watejf* supply sources.
WHO Monograph #42
Chapter 5.
Demouytrat^evaluatiiig these sources in the
field;, /
WHO Monograph #4^\
Annex 4 (p. 271-275).
also p. 39-42.
Assigril students to groups of five.
Assign \each of these groups to a three mile
area.:
i ;
i
58
BEST COPY AVAILABLE
ERIC
-46-
WATER SUPPLY SOURCES
Lesson No. 2
(Continued)
T
Have each group evaluate each source in its
area in terms of
1) location
2) quantity
3) quality. as determined from any
Physical pollutants present and
possible sources of contamination*
Assemble groups to have each group report
;on the feasibility of the water supply
sources in its area.
ERLC
57
-47-
WATER SUPPLY SOURCES
LESSON NO. 3
LESSON OBJECTIVE:
Discuss developments that will improve the
quality and yield of the various water
supply sources .
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS /
RELATED REAPING
.ater Point
Recall the heed 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 ah estimate of
the labor cot" ;
Supervise students in estimating the relative
cost of basic developments for
1) lakes and ponds
2) streams and rivers
3) cisterns
4) 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 #g!_p. 5-7* 11-13.
WHO Monograph #42
Annex 1 9 p. 297-310.
Diagrams or charts
these types of
developments*
of
58
-48-
_ *
SECTION 2
WATER TREATMENT
OVERVIEW:
When the source of water supply 1s not entirely satisfactory treatonent 1s
necessary to insure that the quality of the water meets certain require-
ments. The trainees are Instructed 1n the basic requirements of water-
treatment and receive detailed plans for the Installation of two simple
yet effective treatment systems.
ERIC
59
-49-
SECTION 2 WATER TREATMENT
OBJECTIVE: Determine which of the potential water- supply
sbureesare the nibst ecdhoinically feasible in
terms of any treatment process requirements,
TASKS: 1. Define minimal standards of concentration for
each pollutant.
2. Identify thenature and extent of pollution
for each water supply source.
3. Determine_which type of treatment system
would most probably be necessary to reduce
the pollution level of each source to a
safe level .
4. Determine the cost of a_ treatment process or
processes for each source.
5. 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.
2. Identify the relative costs of different
types of treatment systems.
3. Know the effect various pollutants have bh
different delivery systems.
4. know what pollutants make water esthetically
objectionable.
5. know what concentrations Jbf chemical pollutants
and col i form bacteria constitute health hazards.
6. Identify the factors that influence the future
population trends of a given locale.
7. Recb§hize_the relationship between number of
water system users and treatment process capac-
ities.
\ 60
ERIC
-50-
WATER TBEATMEf^ (cont.j
TERMINAL PERFORMANCE TESTS:
1; Given the designs for various types of treat
ment systems, calculate with reasonable accu
racy tne cost of each.
2. Given aljstof pollutants, correctly list
after each one, 1f applicable:
a. In what circumstances It can contribute
to the destruction of a delivery system.
b. In what concentration It makes water
esthetlcally objectionable.
c. In what concentration It constitutes a
health hazard.
61
-51-
WATER SUPPLY SOURCES AND TREATMENT
WATER TREATMENT
SELF PURIFICATION
Under favorable condi
or river, lake or_pond--will rid 1tse1f_of a certain amount of its pol-
lution by means of natural processes. This self-purifi cation 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 relult,_the pattern of changes is notcrisply
distinguished. If, on the other hand, the water moves steadily
av/ay from the outfall , as in a stream, the successive changes occur
in different ri?er_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 asinglejargl charge^pf |ewage_ is poured into a clean stream,
the water becomes turbidi-sunllght is shut out of the depths * and
green plants , which by photosynthesis remove carbon dioxide from the
water arid release oxygen to it, die off. Depending on the stream
velocity, the water soon turns nearly black. Odorous sulfur compounds
are formed and sdl ids settle, to the _ bottom _fqrmi rig a _ sludge. ^The
settl ed solids soon decompose, forming gases such as ammonia ^ carbon
dioxide, and methane or marsh gas. Scavenging organisms increase. in
number until they match the_f pod supply. The oxygen resources are '
drawn upon heavily and, when overloaded, become exhausted. Lifq in
such waters is confined to anaerobic bacteria_(which exist when ;no
oxygen is available), larvae of certain insects such asmosquitoes,
and a few worms. There are no fish; turtles are generally the only
fprmspfhigher life present. This condition is known as the zone
of degradation.
In a second zone, or zone of decomposition, more sol ids settle but, the
the water becomes somewhat clearer, and sunlight penetrates the sur-
face . _ Oxygf ri is_absprbed from the .atmosphere at the ai r-water 1 nter-
face permitting the establishment of aerobic (oxygen available) con-
ditions. The aerobic bacteria continue the conversion of -organic
matter into nitrates^ sulfates, and carbonates. These, together with
the carbondioxide produced by decomposition as well as by bacteria
arid pi ant 1 i f I, are food sources . •__ W1 th sunlight now penetrating the
water, and with abundant food, algae begin to flourish and form a
green scum over the surface.
83
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-52-
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 w1T I liberate in the say time more oxygen than
1s consumed, thus hastening the recovery of the_streanu Simul tanebusly*
the fish that require little oxygen . such, as__catf1sH_ahd_carpj are aHo
found. As the dissolved oxygen increases, more types of fish appear.
After recovery, in the. zone of cleaner watery fish find th^ stream high-
ly favorable* as[ the ailgae suppbrt vaMous_aguat1c 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 pjj values of water. However, the -
water is still dangerous since all disease organisms haye not perished.
LAKES AND PONDS
Self-purif1 cation in lakesand ponds is brought about by the same pro-
cesses as in rivers arid streams. However, currents are not as strong
and sedimentation plays a larger role, Large deposltsof sludge,_dead
algae, and other organic material build up on the bottom. In deep
lakes, self-purification is aided by seasonal "overturns." This 1s
simply an exqharige of bottom water fbfsurface water* which occurs in
the spring and fall, caused by the difference in the temperature of
the water at the surface and bottom of dees lakes.
STEPS IN TREATING WATER
COAGULATION
Turbidity 1ri watercbhsists bfflhely divided negatively charged col-
loidal materials which are kept in suspension by mutual repulsion*
Turbid water is difficult to clarify by filtration i because, these f1ne_
particlescan cause rapid plugging or even pass through a filter. The
agglomeration of these col loids Into settleable or flltrable aggregates
through the action of certain chemicals iscalled cbagulat1bn A Iron
and aluminum salts are the most widely used coagulants in water treat-
ment plants.
SEDIMENTATION
Plain sedimentation 1s the natural settling of solids heavier than water
without the addition of chemical coagulants. Solids heavier thanwatef
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 theif specif ic gravity,. Large and heavy particles settle
in a few minutes once the water has become still, whereas very small
particles such as clay and silt may remain in suspension for several
days.
Plain sedlmehtatibn ls not ordinarily used as a separate step in water
treatment because the long period required for complete settling would
call for an impractical number of settling tanks. Hgwever_,_1n emer-
gency situations, such as the necessity of taking water from a swift-
J3
-53-
flowino stream which is heavily silt-laden after a rainstorm* special
sedirertatioh tanks may be set up as a first step^ This Initial re-
moval o^ turbidity reduces the load on the coagulation and filtration,
steps 61 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 impuri ties^ Filtration 1s 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
resemble! a small resefyd1r t _ the bottom of which is a bed of filter
sand which in turn rests on a bed of well-graded aggregate with the
largest size aggregate being at the bottom. An underdrain system of
$1]e 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 headerand
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
inchef of sand. The depth of water over the sand bed varies from 3
to 5 feet*
DISINFECTION
In addition tqcoagulatidri, sedini^htation, 5nd filtration, water must
undergo an additional treatment stepj disinfection. This is neces-
sary because no combination of the other three steps_can be relied
upon to remove all Ldisease-producing organisms, the pH and temperature
of the water, the presence of interferring substances* and the degree
of protection afforded organisms, from thedisinfecting 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 piij, both of which are powerful oxidizing
substances. The chlorine available in either of these two_fornis.
rapidly oxidizes the organic and inorganic matter including the bac-
teria in the water. In this reaction the chlorine is converted to
chloride and is no longer 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 recontami nation- during further handling.
< 7 64
-54-
Chlorine Dosage
Dosage is the amount of chlorine added to water to_|at1sfy_the
chlorine demand as well as to prdv1de_fi_res1dusl after a speci-
fied time. THe amount required to disinfect water varies with
the organic content and pH value of the water f the temperature,
the time of contact, |hd the_cmprine_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 milligrams per liter or "mg/l".
Chlorine Demand
The chlorine demand of water is the difference bftween the quantity
of chlorine appl led in_watef_ 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 chlprine-cdnsuming present and the pH value and tempera-
ture of the water (high pH and low temperatures retard disinfection
by chlbri nation}-. For cbmparative purposes, it is imperative that
alltest conditions be stated. The smallest amount of residual,
chlorine considered to be significant ; s 0.1 ppm. The_relat1onsh1p
of the demand to the length pfche contact period is discussed be-
low. Some of the chlorine--consuming agents in the water are non-
pathogenic (non-disease causing prganismsi but this bears ; no re-
lationship to thefact that they contribute to the total chlorine
demand of the water;
Residual Chlorine ^ *
As indicated above, .residual chlorine is the ampuntof unreacted
chlorine remaining at a specified time after the chlorine compound
is added. Chi brine in aqueous sol ut Ion 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. ftit V ayajl a ble ftesi duaLcit l ori ne ; , This is the sum of the
free available chlorine and the combined available chlorine. .
2. Free available chl orine . Refers to hypbchlbrbus acid~ahd
hypochlorite"*ion~present in the water. These are the most -
effective disinfection forms of chlorines The free available
chlorine is a rapid-acting type, important because itcanbe
relied upon to destroy bacteriarelatlvely quickly, and thus
is active cjuMnq th*» period immediately following chlorl nation.
The relative amount of each present in the_water is dependent
upon the "pU value pfthe water. It is Important to remember
that when the pli is raised the quantity of free ayaiVable
chlorine required to kil lthesame number of m1cro-organisms_
increases. With decreasing temperature the same situation of
increasing dosane to maintain the,same_kill_is encountered.
If the cbritact_time_1s._varied, then the dosage applied must
also be changed. For example, tp shorten the contact time
the dosage would have to be increased.
-55-
t
3. Combined available chlorine . This results from the presence
of ammonia or organic nitrogen that will react to form simple
chloramines. Thus the term "combined ayailable_chlbrine ,, __
arises from the fact that the chlorine has combined with an-
other substance. CKloramines are aslofcer acting and less
active form of disinfectant. Therefore, a much higher concen-
tration than that_bf_free availab^ chlorine is needed- to pro-
duce the same germ destroying effect. The specific chlora-
mines present are also a function of pH.
__i • r
Disinfecting Time
Chlorine_demand injiost water is likely to be largely. satisfied
10 minutes after chlorine is added./ After the first. 10 minytes__
of chlori nation, dis1hfect1bn_cbnt}nues but at a diminishing rate.
A standard period of 30 minutes contact time is used to assure
that highly resistant or high di^vase-producing organisms have
been applied. _G|ven a sufficiently large chlorine. content, and if
certain other conditions are met, ^veh such special water_purifi-
cation problems as the presence of amoebi\c cysts or schistosomes
will be solved with. the 30-m1nute -contact period.
DISINFECTION REQUIREMENTS FOR ENGINEER OPERATED FIELD WATER TREATMENT
EQUIPMENT
As has besri previously di seized, the efficiency of the chemical dis-
infection process is dependent upon numerous factors which include
the t$*e and concentration of micro-organisms, the pH and temperature
_bf the water, presence of interferring substances and whether or not
the organisms are protected from the disinfection sblut1bn_by being
embedded in tissue cellf j_br_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 ynitiemplby
coagulation arid filtration as a part of the treatment process and are
capable;of_a high degree of removal of particulate material. When
those units areemployed, sufficient chlori ne_will_be_added to the _ _
water* preferably_b|fpre_Cbagulat^on 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. 1
TABLE 2:
COAGULATION
RESIDUALS
pH
5
6.
7
8
9
10
30 Minute Free Chlorine
Rcsidoa ls in ppm — 1
0.75
0.75
1.00-
3.00
5.00,
5.00-
\
If adequate provisions are not made for accurate and frequent measure-
ment of pH, 5.00 ppm must be used.
66
-56-
The following guidelines were used 1h developing the above table:
1. The water to be treated would be natural surface br^grbund
watlf_pf_ average composition and hot grossly or deliberately
contaminated.
2. Water temperature would be above/ the freezing point*
3. The prescribed concentrations of _ free, chlorine, should. proyldea
reasonable tfargln of safety for all bacteria and viruses patho-
genic to mani Parasitic ova would have been removed In the co^-
agulation arid 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 chl pri nation that wi 1 ] _make_ i t life. Trickll ng 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 A inches
Sand, 7 cubic feet
Gravel
B]pcks_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 leavesand other prganic_mattef . 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 1s al-
ways best to boil or chlorinate water after filtering.
There are severalsarid f 11 ters,_but_thc .trickling 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
|mall_picce| 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 wi]1_ trap mgre snmlLoT9a n lc_f^xter 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 wat^r.
By removing most of the organic matter, the filter achieves /the 'follow-
ing results. /
_ / _-__--/- - - _
1, Removes larger worm eggs, cy$ ts , and cercariae* which are the
hardest_tb killwith chlorine. ■ /
2. Allows the use of smaller and fixeddbses of chlorine for dis-
infecting, which results iri (flririfcable water with less taste of
chlorine. ■ ! /'
3
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68
BEST COflf AVAILABLE
3. Makes the water look cleaner _
4. Rfduces_th|_ainoyHt_of_prgan organ-
Isms and thtlr food, and the possibility of recontami nation of
the water.
the unit shown in Fig.: 21 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
1/1 3th of. an Inch.)
It 1s Important to use clean* fine sahdj but _nbt_tbo_f1nei__TH|_sIn"d_
should be able to pass through a window screen and it is best to wash 1t.
The following points are very Important 1ri 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 outs as thiswl 11 destroy the microorgan-
isms that form on the syrface layer. The best way^ Insure a con-
tinuing flow 1sjto fix*: the water tntajce so that there 1s always a
small overflow. Screen the intake and provide a settling basin to
hllp kefp pipes from becoming plugged^ whlch would stop the flow
of water. This will also delay your having to clean the filter.
2. Never allow the filter to run faster than O.f? gallons of water a
minute per square foot, as It will prevent the growth of micro-
organisms 1h the sand and wash them but through the outlet.— ~
3. Keep light from the sand surface but allow a1f to circulate* as
thiswillpfeyint the growth of green ptant matter on the surface
but help the growth of microorganisms that aid the filtering action.
_'. * ___ _____ ___ ,_•
4. When the flow drops below da jly;needs, clean the filter. This is
done by scraping off and discarding the 1/2 Inch of sand aridllghtly
flklrig of scratching the_surfac|. _Aftfr several cleanings, the sand
should be raised to Its former height by adding clean sand. Before
doing this* scrape the bid sand down i 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 1s descr1bed which uses lauhdry bllach
as a source of chlorine. Although lacking the reliability of a modern
water system* this manual plant will provide s^fe drinking water,. Many
factbfslh this system depend upon operating experience. When starting
to use the system, tt Is best to have the assistance. of an engineer ex-
perienced in water supplies. For constuuctlon details see section II,
C. ■ . j •
Operation
1. Mix concentrated bleach with water in the concentrate barrel
with all valves closed.
/
2\ Fill the plpe from the mixing barrel to the solution tank with
\water after having propped the float valve In a closed position.
3. AHow a trial amount of concentrate to flow 1htb the mixing
barrel by opening Valve #2. %
4. Use the measuring stick to see how much concentrate was used.
5. Close yalyef 2_and open valve #1 so that untreated water enters
the mixing barrel . —
6. Close valve #1 and mix solution In the mixing barrel with a
_ stick.
\i. Remove the prop from the float valve of the solution tank so
that It will operate properly.
8.' Open wide the metering valve and yalve #4 to clean the system.
Allow a gallon to drain through the system.
3. Close down the metering valve until only a stream of drops
enters the funnel. 1
, . \ . ........
\ (steps 2, 8' and 9 may be omitted after.the^first charging of
the system* 1f the pipe mentioned 1n the second step is not
permitted to empty before recharging the mixing barrel).
10. Open valve *3.
Trial and error must be used tbleafhhpw muchcqncentrate should be
put in the concentrate barrel, the amount of concentrate to flow Into
the mixing barrel and the amount of solution to allow pastthe funnel,
the result should be water with a noticeable chlorine taste 1n 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
Chlori nation, when properly applied, is a simple way to Insure and pro-
tect the purity of water. These guidelines include table|_to_give_i
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 j.is.to boll it— see "Boiler
for Potable Water". _ llbwfyer^under controlled conditions chlorinatjon
1s a safe method, and often more convenient and practlcal than bolnng.
Water properly treated Has residual freechlorine which resists ^con-
tamination. Thechlorlne 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.
n
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i
When chlorine 1s added to j*ater, 1t_attacks and combines with any sus-
pended organic matter as well as some minerals such as Iron. There is
always a certain amount of_deid brgaM In water* and almost
always live bacteria, virus, and perhaps other types of life. Enough
chlprlne must beadded to oxidize all of the organic matter* dead or
alive, and to leave some excess uncombined or "free" chlorine.
Some organismsgfe mof^resistant to chlorine than others . Two parti-
cularly resistant varieties are amebic cysts (which cause amebic d^sen-
tary) and the cercariae\of schistosomes (which cause schistosomiasis).
These, among pth^ 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 fdrchlbrineto wpfk A _ Be sure that water is thr-
oughly mixed with- an adequate dose of the dissolved cheffnca^ , c^f.d that
1t Stands for at least 3D minutes before consumption . \
Since both combined and uncombined chlorine has an unpauwac
It is best {arid safest) tb chopse the clearest water ayailable.
settling tank, and simple filtration can help reduce the amount of
suspended matter * especially particles large enough to see. Filtra-
tion that can J>e depended _uppn_to_ remove all of the amebic cysts*
schistosomes* and other pathogen normally requires professlonalstp
set up and operate. NEVER depend on home-made filters alone to provide
potable water. However, a home-madeslow sand filter is ah excellent
way to prepare water for chlorination.
taste,
A
Thus, depending on your water, different amounts of chl prine are_ needed
for adequate protection. Measuring the amount of free. chlorine after
the 30, minute holding period isthe best way tbcontrbl the process. A
simple chemical test using a special organic indicator (orthotolidlne)
can be used. When this is not available* Table 3 may fas used-
TABLE 3: ^"EST^FQR PBOPER CHLORINATION DOSAGE
Water Condition
Initial Chlorine Dose in Parts Per Million (ppm)
No hard-to-kill
organisms suspected
Hard-tb-kUl organisms
present or suspected
Very clear, few
minerals
5 ppm
Get expert advice; in an -
emergency boil and cool
water f 1rst,jthen_use_5__
ppm to hel p • prevent- recon-
tamihatlbn. If boiling 1s
impossible, use 10 ppm.
cbi h i h_the bottom
of an 8 pz. glass of
the water looks
10 ppm
Get expert advice; in an
emergency, boil and cool
first.- If boiling is Im-
possible use 15 ppm.
-62-
In the chart, parts per million or "ppm" means the ratio of:
l)
In water supply terminology, ppm means exactly the same thing as
milligrams per liter or "mg/V'
The secbndchart, Table 4, gives the amount of chemical to add to
lOOQgallons of water- to get a solution of 1 ppm. MultipH the amount
of chemical shown in Table4 5y the number of ppm recommended in Fig A 3
to get thf amount of chemical you should add to leOOgallons of water.
Usually it is convenient to make up a solution of 500 ppm_strength
which can then be further diluted tp giye the chlorine concentration
needed. TheSOQ ppm solution must be stored in a sealed container in
a cool dark place* and should be used as quickly as ppssiblesince it
does lose strength.. Modfrn chlorination plants use bottled chlorine
gas, but this can only be used with expensive machinery t>y trained
experts.
CONVERSION OF PPM TO
Compound
% by weight 6f_
active material—
quantity to add to
1000 gallons of water
to get a 1 ppm solution
High Test (Calcium hy-
pochlorite) Ca(0Cl} 2
70%
1/5 ounce
Chlorinated lime
25*
1/2 ounce
Sodium hypochlorite
(NaOCl)
14*
1 bonce
Sodium hypochlorite .
10*
1.3 ounces
Bleach - a solution of
chlorine in water
usually
5.25*
2.6 ounces
\
73
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WW V5NT
WttT VQ1H
F« MOT CWTrol
i
u
i
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74
,75
I
-64-
WATER TREATMENT
LESSON NO. 1
LESSON OBJECTIVE: Describe and demonstrate how to estimate the
edit of the four methods Used in treating water.
TOPIC
I NST RUCTION AL PROCEDURE
SUPPLEMENTAL MATERIALS/
RELATED READING ,
Treatment
Processes
ERLC
Discuss the process of self -purification*
List and describe the four basic methods of
water treatment:
1) Coagulation
2) sedimentation
3) filtration
Z) disinfection*
Outline the essential. components of sand
filtration and two chlorination units.
Estimate the costs of construction, operation - s
and maintenance for these units.
Manual of Individual
Water Supply Systems
p^ &4-33.
WHO Monograph Series #12
p. 171-193.
Small Water Supplies
p. 26-47 • m
?&
-65-
WATER TREATMENT
LESSON NO. 2
LESSON OBJECTIVE:
Define the pollutants that must be eliminated;
(a) to provide esthetically pleasing and safe water; and,
(b) to prolong the life of the delivery systems
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS /
RELATED READING
Permissible
Levels of Chemical,
Physical and
Pollutants
ERLC
List and describe pollutants that are
1) esthetically objectionable
2) health hazards
3) contribute to the destruction of a
delivery system.
Establish permissible levels of concentration
for each of these c pollutants.
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
WHO Monograph Series #4i
p. 46-54*
77
-66-
v WATER TREATMENT
LESSON NO. 3
LESSON OBJECTIVE: Define the criteria that must be applied in
selecting the most economically feasible source.
TOPie
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATEP'AL
RELATED READING
Criteria of Water
Supply Selection
Review the basic requirements of a water-
supply source. ,
Outline the criteria tobe used in the
selection- of water supply sources.
Small, Water Supplies
p. 8-U
SECTION 3 — -
PLANNING THE DISTRIBUTION SYSTEM
OVERVIEW:
A water%_d1str1but1^ lafge prpject requiring greatexpense 1n
tlmeand -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. effect!. that the exist1ng_facljlt1elj_
the community, the material and financial requirements, Impose upon the
plans he must prepare prior to the startof the project. This section
covers these basic requirements of the planning for a water distribution
system.
79
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THE D7 e9 r 0 yi SYSTEMS
E; SSvelbpji plan for a distribution system which
will meet the requirements of c the given community,
utilizing the existing and proposed facilities.
lr Assemble a list of existing man-made facilities
and potential water sources.
2. Determine average demand; peak demand ind when
it occurs; Irid the capacity of the systw required
to meet bot h the present and projected requirements
of the community*
3. List; the components and characteristics of the
proposed system. These include:
a. Water sou Cc,
b. Pumping equipment ~ type of pump
c. Capacity of distributing reservoir or storage
d. tocatlbn of distributing reservoir with relation
to service connections.
e. Source of energy used in the system^__ . - -""
f. Pipe sizes ind. pipe l^injj^s'iem
4. Chqose the rngft economical aiv 7 r^w'^il source
from amon j existing and prbpr j.*J fo ., ^e*, with the
^ ^fotTowi hg characteM sties :
a. Supplies required Quantity
b. Requires no treatment or very simple treatment
c. System easily Installed
d. located 1hl|Uch_a_pqs1t1on that gravity can be
used as supply, energy ;
5. Choose most suitable site for the ,system facilities.
Choice guided by: '
a. Proximity, to and accessibility from residence
_ <»_ _ _' j _
b. Safety frjom contamination
SO p
-69-
PLANNING THE DISTRIBUTION
c. Safety from destruction
d; Availability of room for future expansion
6. Estimatf theexpected cost of construction, operation
and maintenance, of the whokf system.
7. Identify thesource 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.
<* •
3. Draw topographic map. Estimate distance and scale '
thisj on a sketched map.
4. Classify climatic types and stale construction
precautions* e.g.* Tropical: heavy rain* insect
pests i etc. : ; ■
5. Recognize useful local materials which can be used,
instead of a relatively expensive imported one, e.g.
bamboo pipes.
6. Calculate projected population.
7. Calculuce the capacity of a_itprage_tank_fram/Att
5 oh population and rate of Individual consumption.
8. State factors whicpdetennlne and guide the selection
of pumping equipment. j
9. Recognlje^b^^ make a distribution
^— — — -reserWTr a necessity.
10. necide what traditions can be changed without much
iocial discontent and wtrlch must be contended With.
11. Prepare a chart projecting\expected cojts of mater-
ials and labor, and estimate the required amount of
* money.
TERMINAL PERFORMANCE TESTS:
1. In a field exercise:
a. Classify and measure yield of various water
sources which exist 1n the area.
b. Describe, the rest of the existing facilities i
'i<4
9
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PLANNING THE DISTRIBUTION SYSTEMS fcbnt.)
c. Sketch the system oh a labeled map of the area.
d. Classify climatic types.
, «i List all local materials which can be use«s to
i improve the system.
2. In a given community:
a. Estimate the present * and project the future
population.
b. Determine average daily demand, the peak demand
and when it occurs.
c. Calculate the capacity required by the population.
3. From among many sources^ln the area, choose the
best one to develop, and justify.
4. Estimate the cost of establishing the proposed
system, and prepare a platwfbr financing that would
be feasible in a local Village environment.
-71-
WATER DISTRIBUTION SYSTEMS
JTION SYSTEM
DESIGN
One of the most difficult and baffling problems in the planning of a small
water-supplysystem for a rural community is the lack of criteria upon
which a design can be based. The volunteer needs answers to such /questions
as: "What increase should be allowed for future population growth?"; "Should
proyisipn_be_made_fpr 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. 4
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 fromseveral 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 1ri water-supply^
but the world and that everydesigner should not apply blindly the criteria
listed here; instead, you should be able to make a critical analysis of the
conditions and problems of the area under Itudy and should develop applica-
ble criteria., Iri_so doing, you should contact the health administration of
the area concerned with a viewHo 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 thedesign 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_cbnsidered 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 _c1rcyTnstance|,_qther engineering and structural elements should
be conceived around this need.
Befbfebeginning the actual construction of a village water system, a well
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_labqr._ To be sure that the system is what they want and heed, 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 overall system?
2, Size and Nature of the_Cpmmunity? How many people will be users?
How are ithey distributed? What customs or traditions do they
have that must be considered in the overall plan?
S3
-72-
3. System Capacity: How much Water Is heeded dally? \When are the
peak demands?
v
4. Water Source: What type of _sdurce_w1 11 provide the Viost economical
and satisfactory water for thn system? j \
5. :Proposed System: Location of facilities, pipes* outlets, etc.
6. Site of ProposedFacilltles: An outgrowth ofi the proposed system §
What problems will there be ir obtaining the land needed for the
proposed facilities? j
7. Financing: How will the materials be obtained? Will thi^ project
.be financed by government, cocoperatives, on a cost basis Vetc?
FVI STING FACILITIES ! \
From data collected in Section I, you have already quite fully analysed the
types of .source! .available*, and _eva]uated_e£Ch_as_a potential water source
for a water system. How, yoq need to concentrate, on rpatching the sources of
water to the existing cbninuhity. This 1s accomplished by: [
U Adding to the topographical I map el ready started, the distribution
of the users in the community. \
/ \_ -
2. Considering local customs and traditions regarding water uses* arid
needs. \
3. From (2) above* calculating system capacity requirements t arid \
system proposals to satisfy those requirements. I
SIZE AND NATURE OF THE COMMUNITY '
• - -
The proposed water system has to be bullet around the customs and tradlti *_
of the community it will be serving. For example »__1f the sccia] patternslof
the community are tjullt.aroiind family ^ructures, 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, 1n most parts of Africa, men swim upstream,
r arid^wbmeri_ddwristr^am. Or men first, then women. !n_ Moslem countries womeri
do not. appear in public unveiled. For an outsider, Peace Corps are outsiders,
to institute an acceptable riew systemin such areas, hehas to study very !
carefully all such traditions and then modify his system to suit the com- 15
mariity. If he cannot adjust the $yster, he should "^y to get his point
across by explaining to the pebplMor their representatives) why it is
Important that he interferes with 'their life. Tor example: in the Moslem
cormiunity cited, the best pflah would be to distriNte water Into he uses
iristead of establishing public wells. It mast be e Tp';asized that in order
to establish the most effective p; n, a thorough . jdy. of the community j
must be done by the planner. Usually a_di|cussiqn with thelocal authorities
will y'eld a good result. Remember, when help is imposed from above, it .
ireets with resentment and failure.
84
-73-
In describing the community, care should be taken to determine population,
both present and projected.
Population growth 1s determined by:
1. Future economic developments In the community.
2. The cnaracter and location of the community 1h relation to other
population centers.
3. The presence or possible Introduction of small Industries Into
and around the community (the Installation of water scheme itself
will cause population growth.)
fs ccrsnon acceptable estimate for future population growth In most rural
erris* 1s a 50% Increase 1n 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 1n a way as to allow for future
expansion.
Example bh projecting population:
Original population
Increase over lOyear period 50% bO.QQQ
Projected population in 10 years 150*000
Relationship between population and storage Capacity:
The required capac 4 .y f ' * a storage tank equals half the total daily
Water requirement.
Total daily water requirement » average demand x population + larger users.
j t
(La-ge users would Include public centers, schools and factories. If
theue are hot 1n the community, chen the last term 1s left out;
Storage Capacity « l/2[average demand x design population + large users]
SYSTEM CAPACITY
The methods for evaluating each type as a potential w ^er system source was
covered h Section U For each source you will have to determine Its yield.
This is the ^xlmum quantity of water that ««• be drawn f ™ a fource in a
g,/lh p«Hou of time: To calculate the ylelc for a source of water you.
1. Draw a measured quantity of water from t..e source;
2. Time how long 1t takes ci.e source to replenish the drawr quantity;
3. Divide the amount of water drawn by the time taken to refill.
Yield is usually ;ta**»H in aallons oer minute. Below are examples for
estimating yield tor -arious types of water sources.
86
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-74-
Flg. 24 Cistern Catchment Yield
55
i
CO
1
Sj
ISO ZOO
aOO 40O S90 ',90 1M 900 ywO \JOO 1,000 s OOO HSOQ S 6 T ft 9
HarixoNtoI Catchment Are* in Squirl Feet
HawzaNT'.L a#ca ar
MJV£- HALF THI*
86
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-75-
a. Cistern Catchment Yield
To estimate your catchment area the minimum yearly rainfall and the
amount of water required by the family during _one_ ;r jaf j_must be esti-
mated. Spmetlmesj the government meteorological section :an give you
the frlnlmum rainfall expected. If they do hot* 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 noeded (Fig. 24 )... Suppose you have a
rainfall of 60 Inches a vear and the family needs 20 gallons a day.
then... 7
2/3 x 60 equals a :. uirtm raihfSIl of 40 inches a year
365 days x 20 gallons a dt ■ ^ouals 7300 gallons a year
Thechart shows that a catchment area of aboyt 300 square feet 1s
needed to supply the family with enough wat ° for one year.
b. Yield of Small Streams
This is a rough but very rapid method of estimating water flow for
small streams. The number of streams that must bemused and the flow
variations are Important factors determining the necessary facil-_
Ities for utilizing the water. Ksre is a_way to flirvfya water supply
problem quickly by allowing you u> take rapid flow measurements.
The equation for stream flow is — g » K x # x V
Q ■* flow in gallons per minute (S.33 pounds « 1 gallon)
A * cross section of stream, perpendicular to flow, in square feat.
V » stream velocity, feet per minute.
K « a corrected conversion factor since surface flow 1s normally
slower thah ayerage flow. For normal stager use K « 6.4; for
flood stages use K * 6.7 to 7.1.
t
\
i
i
•
i
»
i
l
pi
: :•
-1
*****
»1
1111$
Pi
t
i
1 'I
}
m
mm
\ foot
Foot \
F1g. 26 Cros s Se ction of Stream
To find "A" . . . the stream will probably have different depths along
its lenqth so select a place where the depth. of the stream is aver-
age. l!tlke a melsurlng Stick and place 1t upright \"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
ill depth., move the stick three feet -from the bank, note. the depth,
and continue movlnq it -t one-foot lengths until you cross the stream.
Draw a grid! like 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 watery beestr
mated. For example, the grid shown here has about 15 square re" ot
water.
To find "V" out a float in the stream and measure the distance of
SaJel 1n one Snute " (or Action L cf a ^nute. lf necessary ) The
width of the stream should be as constant as possible and free of
rapidS, wh»n measuring the velocity.
Example:
Cross section i : 15 scuare feet. M ;-zi
Velocity of float =25 feet traveled 1p 1/2 minute
Stream flow is normal
q = f.4 x 15 x 20 feet
.5 minute
3800 gallons a minute
WATER SOURCE
Factors to be considered In the selection o- a water source Include the
following:
a. Purity of the source.
b. Proximity of the sourrs: tj the community
c AH!t. 4 de of source above service connections
8S
^77-
d. Temperature variations of water from the source.
Guide to choosing a source:
First choice, a source that
- requires ho treatment
- uses gravity for distribution energy
- requires minimum maintenance
- 1s cheap to develop
- e.g. springs
b. Second choice, that which
- require no treatment
- but must be pumped out and Into the -aptly lines.
- eg. wells.
c. Third choice that which
- requires simple treatment
-uses gravity for distribution energy
- e.g. catchment cisterns.
d. Fourth choice, that which
- squires simple treatment
- must be pumped
- e.g. rivers
PROPOSED SYSTEM
SELECTING SITFS FOR THE SYSTEM'S FACILITIES
1. Source - must be near to the LCdmSiunlty (see above).
2. Pwnp station •should be above the highest probable fVooC level;
or be suitably protected against flood.
- should be accessible at 11 times
- should be largeehough. to meet future expansion.
- should have suitable topography
- should be well protected from possible sabotagere.g.
•^_ei_ *1ng_1t_ within an Industrial type wire fence
with a indeed gate.
3. Storage Tanks - should be cehtrally located
. possible, should be put on the highest ground in
the area.
83
-78-
PUMP SELECTION
The most Important considerations 1n selecting a pump ere*
1. Ihe skill of the operators and maintenance men available
2. The initial cost of pump and driving equipment
3. The cost of Operation and maintenance
4. The capacity and lift required
5. Availability of power to operate the pump - a -n--
6. The sanitary features of the .pump! available [.conrorxlally;
7. Type of source 1ri which the pump 1s to be Installed! including the
. depth of static water level from ground surface.
8. Reliability of equipment, and availability of spare parts.
Th- following 1s a general guide to the selection of pumps for rural
water-supply systems:
1 . Structure of the pump
a. m movable parts above ground and easily accessible are easy
tc maintain. Suitable for arear with no skilled maintenance neo
b. If skilled maintenance men are available, first choice should Be
pumps with submerged cylinders.
2. Type of power available; Power-driven pumps must be of high effi-
ciency to reduce the cost of power.
3. Design of the pump: The pump design should be flexible enough to
be used in a wide range of sources. There are some purops^whlch
must operate under the conditions for which they were designed,,
e.g. deep-well turbine and centrifugal pumps .
4. Repairs: The selected pump' must be of a type for which repair and.
replacement parts are easily obtainable.
5. sanitary Standards : ..The -pump-aifd" equ1 pine.it must be constructed as
to prevent con tami nation of Water either at source or enroute to
storage. Specific sanitary conditions to be considered:
a Pump head should be designed to prevent contamination from
environment from reaching the water-chamber of the pump
b. The base : ■"•'Yd be waterproof.
c. The pump should not need priming
Information required when ordering or Inquiring abut a pump.
1. The inside diameter of *ole or casing 1n which the pump is to be
Totalled.
2. fhe static level of water 1n well, measured -'rom ground level.
3. The desired output <n gallons per mi:.dte.
do
pomps
TABLE; 5 ; ADVANTAGES A ND DISADVANTAGES OF VARIOUS TYPES OF PUMPS
POSITIVE DISPLACEMENT
Usual well I 22-25 ft shallow
pumping Sell; up to
depth (ft) I 600 deep well
Capacity
Gallon?/
Minute
Efficiency Jaw; can.be
range (J) proved with
Maintenance.
Cost
3-15
Very Staple
Simple, but val-
ves and plunger
require atten-
tion; more dif-
ficult when pump
c iinde? is in
tiv v '1
tow, but higher
when cylinder
is in the well
motor.-wind dri-
ven, plunger type
22-25 ft shallow
well; up to
goo deep well
10-25
tow; can be im-
25I-60X
chain or contin-
uous bucket
Depends on valve
being lifted and
type of power
4-20
Low
Simple
as.
pump; mainten-
ance of motors
sometimes diffi-
cult In rural
areas
Low, but higher
when cylinder is
in the well
VELOCITY
centrifugal
10-20 ft
Very wide
range: 2 to
unlimited
Good;
505-851
Simple, bud
attention is
necessary
deep-well
50-300 ft
pr J
jet
Very. wide
range;
25-5,000
^ood;
65I-80X
More difficult;
needs attention
More difficult
and constant;
skilled atten-
tion is neces-
sary
15-20 ft below
5-125
Low: 401-60J
Simple; air locks
can cause
Reasonable
Simple, but
attention is
necessary
Higher, espsj-
ERLC
91
92
I
TABLE 5 (Cor , , .ANTAGES AND DISADVANTAGES OF VARIOUS TYPES OF PUMPS
POSITIVE DISPLACEMENT
VELOCITY
Types of
pumps
hand pumps *
plunger type
mowr» winu un-
ven, plunger type
rhxln hr rnntin*
WHO 1,11 U] VyU*M'
uous bucket
centrifugal
deep-well
turbine
jet
Power
Hand or animal
Hind, motor
Hand, animal,
wind, motor
Motor
Motor
Motor
Advantages
Low speed; easily
understood by
unskilled people;
low cost
Low cost; sim-
ple; low speed
Simple; easy to
operate and
maintain
Eff'^Mt;
wide ,*nye
of capacity
and heaJ
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
lore difficult
when cylinder
Is in the well
Lew 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
-81-
ERIC
4. The lowest water level expected during pumping.
^ j " ■ '*
5. The desired water pressure at ground level.
6. 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.
I
Pumps.
The types most commonly used In small community water systems
are:
1. Hand-or /power-operated reciprocating pumps with the cylinder
' above the grcund.
2. Power-ojlerated centrifugal pumps with pump mechanism above
grounds;
» 3. Hand-power-, or wind-operated reciprocating deep-well puSps,
with cylinder 1h the well.
4. Deep-well turbine pumps driven either from the surface or from
• a submersible electric motor.
5. Jet primps, power-drlveri at surface.
6. Hydraulic rams
7. A1r-I1^t pump, operated by power-driven compressor on the
surface.
Classification; c|f pumps (see Table 5 )
ly Displacement a) Reciprocating
• b ) "Rotary
| c) Chain
V
3. Airlift
4* Hydraul
f
b) Jet
2. Velocity a) Centrifugal
1c rams
Where various pumps are used:
1. Reciprocating plunger - 1h wells mainly. The most commonly used
pump. s
9S
J
i
1
-82-
2. Semi-rotary pums - for low 11ft - e.g. from welU arid cisterns
to overhead tanks.
3. Rope-and-bueket systems - in open duo wells. Either hand or wind-
less operated. .
4. 'Chain-bucket pump - Jn open dug wells.
5. Chain-and-plag bucket.
Multicellular band pump. j
Centrifugal pump - in deep y^lls.
Jet pump - in deep wells. ^
Ajirji ft pumps. - in drilled wells and wells with Irregular sides*
Ajirli
ajlsf
for pumping muddy water.
10.
Ijfcfraulic Rams - In springs, streams arid rivers.
Examples of various pomps.
tZ ZZXLt^Son b.ew..n ran, and SgSA prtnt ao which wa t ,r i, to b.
vnted— pumping head *
E ri T6tal length of supply pip* _ _ : : _ -j—
F * Suhd-plpe. neceuary in cue of exceedingly long drive pipe
problem.
/
and E It rt*e*»»a<7, With
fallibility, ate
Fig. 27 Hvdraul 1c Ram
0
ERIC
as
BEST COPY AVAILABUj
-83-
Fig. 28 Typical Ihstal latibri of Jet Puhip
H
4
-I
B
A - Water being return-
A
ed Irpm pump above
B «
8 - Water from well
c ~
being incited up into
O -
throat (D) by high.
E
velocity discharge
(C)
Q
H
jei membjy
Water line fr<
Rising water
Discharge pipe _ _ _
Height of water puthed by Jf_t__
o. 1S-20(t)
Fig. 29 Displacement Pump Operation
A - Down-stroke: Cylinder above plunger nil* while *alve at base of cylinder doses, and valve In plunger
B - Upstroke: Cylinder full of witer aj>ove jWun t er_is ^
pUmp opens, r.mng cylinder below pluogrr. A, plunger rises, a vacuum is formed below, pulling water
__ihio the cylinder, : _ : ;
When the cylinder Is above ground, a foot valve is necessary to avoid pri img.
97
ERIC
-84-
0
ERIC
AJaricd by kind pertniition Trom ^-r. im. F. D. A Enwry. T. i. <i*42> ^-rfcT* H-mbr,,' umt Mm fintr,' No I.
St» >i>f^. P. 2741. "
F1i. 20 Elementary, Single Acting Force Pump
» the foot and bucket valves the lift pump, a *tad valve is provided.,
jn operation, durlnj t^ie up-ttroke^atmoipherlc pressure 'orCes water into _the cylinder;
down-ttroke. this water is trahsferrea from the lower tO the upper side of the piston.
F-g. 31
Centrifugal Pumps
This is the be»t and simplest arrangement for centrifugal pumps. Power whit may be
electric motor or internal combustion engine.
Belt-driven centrifugal pumps are common but introduce belt maintenance. Necessary
in order to f et the correct ehfihe.pump speed ratio.
Tht» manufact ur er *' recommendations for operation and mainten*
owed.
98
MilE
-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" (ID foot "head" represents
the pressure at the bottom o f _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
1" 2" 3 r 4" 6"
8" 12" : 24"
F = approxi-
mate friction
head (ft.) per
100 ft. pipe
16 7 5 3 2
1 ,/2 1 1/2
l- ii — -i - F x length of pipe
Friction boss Head •= ^
Any bends, valves* constrictions, and enlargements (such as pessihg
through a tank) add to friction. The equivalent pipe length of
such "fittings" in the pipe line should-be added to the pipe length
used in the friction Toss equation.
5. Obtain "Total Read" 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. Readmptprlhorsepower 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 all
information 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 M _(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.
99
-8b-
< j KJ
*f -
! i
Fig. 32
TOTAL &£AD >n «Tr
I
% p -
' - 1
n 1
4*
WflTffR HORSEPOWER.
S . _
PISeMfiRSE t=T*/5KC or- £t/SGC
-i— r~n~r
1 | 2 s e ? b e h
«* «■ ill x K V\ v" w JA O E
PUMP 312 C (ovTt-ST Vfc** &i)
MOTOR fcW?S£1«Wr« a
s
100
ERIC
-87-
If you plan to use human power for the pump, figure that a man can
generate about 0.1 tl.P. for a reasonably long period and 0,4 H. Pi
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:
a. Galvanized wrought-iron and cast iron
b. Asbestos _
c. Transite (mixture of cement and asbestos fiber)
d. bead
e. Copper
_____ f .._ P.laslic _^ . - —
g, Bamboo stems and other related tropical plants
h. Wood-stave, made but of light wood
Measuring diameters:- The diameter of a pipe 1s 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 1s 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 tbesame returns as tbpse 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_1ndiv1duals concerned with the problem will
look far enough for a good case to present to their legislators or to
financial institutions,. Long-range plans 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 all successful programs, federal or central governments have
shouldered the responsibility for financing the. construction of small rural
water projects. In many cases this decisionwIH 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 pr1vate_bariking1nst1tutions, the central govern-
ment must usuallyflll the role of provider of funds. In some places the
states or provinces co-operate- In many countries, the normal pattern 1s
for the central government to loan the necessary funds directly to a local
cofttiiunity at a low rate of interest or to make a partial grant. w1tb_the__
community and state jointly, supplying the remainder. Loans or grants are
made on the ba|is of projects presented through proper channels for approval
by state or federal engineers.. A sanitary engineering section ina central
health department would be quail f ledand might be available to provide this
technical service to rural communities.
101
If _ybu_plari to use humah_pdwer_fOf the pump, figure that a man can
generate about 0.1 U.P. for a reasonably long period and OA H.P.
for short bursts. From this arid the total head, ybli can predict
the flow you should design the hand pump for.
Pipes
Most commonly used pipes are made of:
a. Galvanized wrought-iron and cast iron
b. Asbestos _ _
c. Transite (mixture of cement and asbestos fiber)
d. bead
e. Copper
f.._ Plastic . - —
g, Bamboo stems and other related tropical plants
h. Wood-stave, made but of light wood
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 thesame 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 theindividuals concerned with the problem will
look far enough for a good case to present to their legislators or to
financial institutions. Long-range plans have been effective in many .
countries throughout the world, both iir 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 all successful programs, federal or central governments have
shouldered the responsibility for financing the. construction of small rural
water projects. In many cases this decisibnwill 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 pr1vate_bariking1nst1tut1ons, the central govern-
ment must usuallyfill 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 qovernment toloan the necessfary funds directly to a local
cofttiiunity 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 batisbf 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.
101
.89-
FtAwriiiie the DistiiiBufioN systems
LESSON NO; 1
<*
LESSON OBJECTIVE; To determine existing facilities which may
be useful ar. part, of the planned system.
TOPIC
INSTRUCTIONAL PROCEDURE
SUPPLEfciEMXAL MATERIALS
REL A TED RE ADING
*ater Sources
tanps
ipee
ioographic
Locations
Lecture on various types of possible water
sources and their characteristics.
Show how to use t abler, 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 goi v
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..
P^?rt_giying_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*
ERiC
103
-90-
I'LANNING THE DISTRIBUTION SYSTEM
Lesson Kb* 1 (Continued)
Local Materials
Lecture on climate of each region.
Discuss in class possible hindrances to
.construction work.
Group them on the board under causr*tives.
Lecture on _trade-off _valuesj e.g., quality
vs. expenses to achieve convenience*
Discuss in class the materials which can be
adapted to suit an improved distribution
system.
104
PLANNING THE DISTRIBUTION SYSlEftS
LESSON NO. 2
LESSOR OBJECTIVE: To choose the most suitable source for development
J - :
! and select a suitable site for the system facilities.
TOPIC *
INSTRUCTIONAL PROCEDURE
SUPPLEMENTAL MATERIALS
RELATED READING
selecting Water
Source
Discuss the possible combination of '
characters n source can have.
Section bri Sources,
fcet each student draw the character! sties of
the source he would choose first.
Discuss the feasibility of each proposal.
Formulate a guide to quick choices,
■
WHO Monograph Series #42
pp. 34-35-
lecting the
te
Discuss the importance of proper locations
of facility sites.
Draw a guide to site selection,,
Suggested Design Criteria
for Waterworks in
Recreational Areas,
Sections -2*4 and V3*
\
-92-
PLANNING THE DISTRIBUTION SYSTEMS
LESSON WO. 3 |
LESSON Oi3^€CTIVE- To select pumping equipment most suited
for use in rural areas.
TOPIC
INSTRUCTIONAL PROC EDURE
SUPPLEMENTAL ^MATERIALS /
RELATED READING
Oh.-trac tori Sties
of i : umps
Ask students to recall characteristics of
pumps ;
Discuss oith students what would be the best
guide criteria for choosing a pump i ^
Section on character-
istics of pumps •
Pumps and/or pump
models .
ERIC
108
-93--
. i > ■ ■
" ' PLANNING THE DISTRIBUTION SYSTEMS ^
- - L ESSOIN NO. 4
5SON OBJECTIVE: To describe the community to be. served;
snecif ically, theV' aspects that affect the plan.
TOPIC
'_ INSTRUCTIONAL PROCEDURE _ _ _
i ?
Lecture cri hbW to er»tiihate; t.he population of •
a community. *
Show how -to calculate projected population
and relationship between population and
demand. y
Discuss the importance of long established
traditions. ^ |
Discuss what traditions, axe iJr^cely to clash
with the planned system arid How to avoid
such a clash.
Discuss the connection between occupation and
water demands. ^
Relate type of houses to distribution systems
Compare availability of skilled labor in U.S.
to undcr-fieveloped cbuhtri.es.
■_ _. V
Discuss how to select workers for the prfcject
SUPPl^ttERTAL -MATERIALS :' >
RELATES REAPING
. 1 « t,i oh
it ions and
1 iiti'uoture
ic Standard
WHO Konogroj.il :><;r1'::r
p. 42-43-
/
> A *
107
PLANNING THE DISTRIBUTION SYSTEMS
LESSON NO. 5
LESSON OBJECTIVE:
To prepare a chart projecting expected costs 6i
material and labor. Estimate the required axnos
money and how to raise the money*
TOPIC
: INSTRUCTIONAL PROCEDURE
Cost
Discuss how to estimate the cost of the
project*
FinGfiicing
Discuss various methods.
\
*
. — i
\
•
— •
" .'
108
SECTION 4
riCS Ql-AN-ADEQUATE SYSTEM
OVERVIEW:
There are many technicc.1 problems and factors tb.be considered in the
design of a_distributidn syster 1 . The layout of the system^ the sizes of
the pipes, the loss of pressure, and many other factors mast be considered
in the actual planning of the system.
This section provides the trainee with an understanding of the^character-
istlcs of an adequate system, Uith this_uhderstandihn he will^e able_td
plan Uie technical aspects of the project and avoid mistakes in x ttie con-
struction phase of the program. V
BEST COPY AVAILABLE
109
CHARACTERISTICS OF AN ADEQUATE SYSTEM
OBJECTIVE: Define and evolve a detailed plan for the con-
struction of the basic components in ah adequate
system.
TASKS: 1. Draw to seal e_ the plan and profile 11 lustra ting
the relative locations of the component parts
of the system.
2. Prepare a detaijedaccpunt of the characteristics
of the_cHosen 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 i treatment plant or dlstflbutlpn reser-
voirs, and the sanitary precautions to be taken.
5. Describe the safety_prlcaut1pnl_Vp be taken
during' the construction and operation of the
treatment plant; i.e. i to avoid recontaml nation
and protect personnel .
6. Determine the storage requirement for the system.
7. Based on the location of the tank* select the
materiaHs)-tb be used In Its construction.
8. identify sanitary and servicing prdvlslbnstd
be followed 1ri constructing the storage tank.
9. Decide which system of distribution best suits
the community.
c
10. Determine the required pressures at service
connect! ens and_des1gn the pipes and joints
for distHb'.itlna.
BEST COPY M*MLE
110
-97-
CHARACTER1STICS 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 beinclgded 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 betwfen distribution systems
and various contmunity patterns.
6. Calculate required head, hfadlpss^ Read from
tablesthe 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 editing paints.
10. Recall safety standards to be maintained in the
construction and operation of a system.
TERMINAL PERFORMANCE TESTS:
1. For a given cowunity layout, design a distri-
bution system which best suits it* and draw_tp__
scale the plan ahd_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. In a given trfatment system, state in detail
« what happens as the water passes through the
successive stages.
...U 111
ERIC
CHARACTERISTICS OF AN ADEQUATE SYSTEM (cbht.)
4. Given a source and treatment plant, and/or
distribution resei^plr some distance apart,
list all sanitary precautions which should
be taken while transferring the water.
5. List all sanitary and personnel safety pro^
visions to be taken into consideration while
planningthecohstruction and operation of a
treatment plant.
6. Chposltheappropriate materials for construc-
ting storage tanks,
a. underground
b. on the ground
c. above the ground
7. Determine the difference in height between a
given storage plant andlefvice connection^ and
calculate the required he*d and headloss in the
section.
8. From given tables* choose pipe sizes that will
deliver water with a specified residual, pressure
at a service connection distance ( ) units away.
Us
-99-
WATER DISTRIBUTION SYSTEMS
CHARACTERISTICS OF AN ADEQUATE SYSTEM
ESSENTIAL COMPONENTS OF AN ADEQUATE SY S TEM
SOURCE
The source of water for the. distribution system roust meet the require-
ments that have been established for quantity and qua 1 ity. 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_^
can be built to compensate for this deficiency. The quality require-
ments for drinking water are generally established by local or national
bf ?lth departments . ( If none exi st , you shoul d 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 wel 1 s 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 comnunity should strive, the construction of wells (if necessary)
wouJd 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 thepreseryatiphpf potable water, the following protective
measures should be taken:
1 . Wells and pump bases should be sealed so that surface water
is unable to enter the wel 1 ; ~ ~
2. Mater used to prime pumps must not be polluted" (when possible
use pumps that do not need priming) •
3. Only trained workeVs should be responsible for maintaining the
system once it has been built. (Initially* care should be
taken tosflfct workers who are healthy, and free from communis
cable diseases) •
TREATMENT FACILITIES
In selecting a water source* the goal is one heedinghp chemical treat
ment (other than disinfection) prior to use. As stated earlier, if no
such source already exists, explore the. possibility of awell construe
tioh program.* When an acciptablerbytrless-than_d||1ra
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
guallty ofwater that_does_not meet drinking water standards. The
methods for evaluating water and selecting treatment processes is
discussed in Section 2.
To"r further Information refer to the Peace Corps training manual
on the Construction of Sta ter Wells
113
BEST COFY MAILABLE
ERIC
-100-
DISTRIBUTION RESERVOIR
In small distribution systems* whether, thewater Is obtained by gravity
or by pumplhg^lt is always desirable to provide a distribution reser-
voir. T he ma 1 n reasons-arei- — — _ _
1. Hpurlyyariatlons in the rate of consumption are more easily
satisfied Un small systems, such variations may be three
ttmes the average hourly consumption and sometimes more);
2. Adequate pressure can be maintained throughout the distribution
system; 1
3. Adduction pipes between the source of supply and the reservoir
maybe repaired without interruption of the village water ser-
vice, - --
4. Provisions maybe made forfire protection.
5. Pumps can be operated uniformly throughout the day, (Such pumps
may be much smaller than would be_requ1red otherwise)^
6. The size of the adduction pipe between the supply source and
the reservoir can be made smaller than would be necessary 1f
the viWfcge were fed directly from the water source.
7. Fluctuat1ohs_1n_peak_per1ods of demand can be more easily ob-
served and compensated for when all water is drawn from a dis-
tribution reservoir. v
The first consideration when designing storage is the capac1ty_wh1ch_w1ll
be provided. This to a great exteritdepehds 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.
Condi tTonsTvar^ in different parts" 6f We ^rl<f,_but_a typical pattern
of draw-off in a vlllageisas follows— 30X 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 sunfetand sunrise, tocal cus-
tome wlllprodyce local variations; for instance^ in Moslem countries
the demand during Ramadan will be high at about 3 am.j_ahd_1n other
parts of the world where Monday is the_trad1t1onal_ ,, wash-day M the Monday
morning draw-off may be equivalent to the total supply of another day.
These considerations must be taken into account wheri assMslng the ex-
tent and duration of p|ak_draw-pffs;_th1s must then be balanced against
the rate and periods of water delivery.
When wateris 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 throughoutthe twenty four hours. Obviously
in such a method of working a smaller delivery wain is needed than if
larger quantities are required in shorter periods. __When_electr1c1ty 1s
used for pumping 1t is usually m ost econom ical to operate for about
twenty hours a day, leaving the pumps idle djririg the peak hours of elec-
tricity demand. With diesel- or gasollne^Hven pumps, the cost of atten
dance (generally cohtinuqus w1 th such engines, but normally unnecessary
with electric motors) becomes art important factor and bne shlft^qfeight
hours, or two totalling 16 hours, 1s a frequent method of operation.
114
-101-
I t is quite common to find schemes desighedto 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; hot only do labor costs increase but the wear oh machinery
working continuously, throughout theday and night becomes excessive
and^:he-14fe-a^theH^^t^1^correspondingly shortened.
To deterftiine the ampunt that _wil 1 be required td_ provide
uniform serice throughout 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
Ahadequate system is one which will deliver tfie requlrfH 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.
SYSTEM CAPACITY
Once these factors have been determined, the storage capacity can^be
determined. The following guidelines should be considered 1n arriving
at adequate storage capacity:
y._ As a n»l»-nf- thumb, the s torage-required s hould be approxl-
mately equal to a days consumption of warer. a -
2. Minimum capacity should be large enough to handle morning and
afternoon peaks. In hb case should 1t be less than half a
day's supply.
3. If It ts not possible to storeaday^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 1n 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 waterfrom several sizes
of pipe When you know the height of the water source.
The nomograph applies to steel Pipe. F1*. 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. Tomake this measurement with
any accuracy^equlres some type of surveyor's Instrument.
To use the nomograph, first find the number 6f_ pipe diameters
thef* are in the pipe lengths. This 1s accomplilhed by dividing
the pipe diameter 1n inches into_12_x pipe lengths 1n feet; or
divide the pipe diameter 1n centimeters Into 100 x the pips fc
length in meters.
Then with the straight edge connect the pipe diameter on the d
scale 1n inches (1 inch « 2.54 cm) with the reservoir height 1n
feet bh 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 1n the pipe lengthas calculated and observe the
readihcj oh the Q scale. This will be the discharge in gallons per
minute.
v He
Index -
Scale -103-
r-7
-5
-4
0
0
O
•H
*4
O
O
o
§
-p
9
I
•P
Cl
M
-3
~2
-1=0
..7
..6
fc-5
I
U
O
rH
—1.000
-400
-400
-Joo
-Zoo
— I o©
P-aoo
4*6
I-.2
-.15
Li
o
03
- 10,000
1 6,000
-4\©00_
So-
4o-
*0-
-30
— 10
— 3
.6
—a,
u.i
3»=
10-
i-
*-
4-
2*T
1—4
10
-30
-P
O
•P
01
9
3
m
o
iH
3
1
«P
(D
ft
5
-50
-*°
-et>
-50
-100
-3*>
— #oo
— 6X0
—too
— >oo
Soo
— *oo
—MOO
-l,*00
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. Determtne the quantity of flow desired in gallons per minute.
8,33 pouras.* 1 gallon.
2. Measure the hetght of thfl if t_ required (from the point where the
water enters thepump suction piping to where it discharges J
117
-104-
Example:
Assume a reservoir height of 3D feet* a pipe size of 1 1/2"
diameter and 100 feet 1h pipe length, what will the discharge
rate be?
First divide the length by the diameter each in inches
1208 ____
~77T « 800
now convert 1.5 on the d scale^wW-3(rfeet-on^be h , ^l*!!!
make a mark dh thejndex scale. Connect this mark with 800 op
the L/0 scale and read the flow as 60 gallons per minute on the
Q scale.
Headloss Calculation
Hdw_to_compensate for the headlossesdue to pipe fittings:
in terms of the equivalent to the length and size of pipe which
would produce an equlyilent loss 1f, Instead of adding fittings - 9
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 fqulvalent length of pipe for friction
loss in valves and threaded fittings
Diameter
Of fitting
htkrn
H
H
K
1
\%
IK
2
2«
3
3H
4
5
6
90*etd.
ell
1
2
2. 6
3
4
5
7
8
10
12
14
17
20
45 # atd.
•11
0.6
1.2
1.6
1.8
2.4
3
4
5
6
7
8
id
12
W aide
tee
M
1.5
3
4
5
6
7
id
12
15
18
21
25
30
Coupling
or atraigbt
rim
rut
a3
0.6
0.8
0.0
1.2
1.5
2
2.5
3 _
3.0
4
5
6
Gate
valve
as
a 4
0.5
a;
0.8
1.0
1.3
1.6
2
2.4
2.7
a 3
4
Globe
valve
M
8
15
20
25
35
45
55
65
80
100
125
140
165
Angle
valve
M
4
8
12
15
15
22
28
34
40
50
55
70
80
ERLC
i
118
-105-
RELATIONSHIP OF DISTRIBUTION SYSTEM TO COMMUNITY
ARRANGEMENT OF THE NETWORK
There are two main systems of distributing waiter in a community:
Dead-end System
This consists ofdirect lines from the mains to the outlet without
ihter-cbhhected lines (see Fig. 35 ).
Evaluation: 1, Easy to install
2. Takes_less_material for pipes ,
3. Best for small , unplanned community layout.
4. Disadvantage: If water not used often may breed
— bacterlal^at the_stagjiant end.
BRANCH
CD
CD
Fig, 35 Dead-Ehd System
Loop System
In ThisTthe ends of all the "supply lines are_ connected so there,
is continuous flow of water in the system while it is being drawn
from any point in the loqp (see fig. 36 )
Evaluation
1.
2.
3.
No stagnant water.
Less vulnerable to breakdowns since. valve arrange-
ments may be made to re-route the flow of water,
isolation small trouble areas^
Suitable for well -planned community.
Fig. 36 boop System
119
-lee-
Generally, In a large community* the loop system can be used
around maih_res1dent1al_pr business areas; and the dead-end
system for the rest of the system
The network of pipls should bfar ranged so large primary mains feed
smaller secondary pipes. Branches or feeders carry water from mains
to service connections. Service pipes carry ^ater from the branch to
the building.
headloss and distribution systems
Head
In planning a distribution system it 1s desirable^ to draw water at
a tap with a good pressure^ ntr. too Mgh nor too low. Required head
is the height (or depth) of water _which_^
pressure. Pressures are expressed in pounds per square inch (psi)
in height units (ft.).
or
f •
Water Head
Water "^4^." -
. . j .
1 *- 1
L «• I
Fig. 37 Head Measurement
Relation 6? Pressure and head: frbm the definition dfhead andsome
' ^raulic factors*. 1t_can_be shown that 2.31 ft. of-4?ater exerts 1 psi
iz its base or 1 psi exerted at base of water sol umn wtl^ raise it 2.31 ft.
Example: Calculate the pressure exerted by a column o
at its base.
er 100 ft
2.31 ft. exert 1 psi
196 ft. exert _ 1 x 100 ps1,» 43.3 ^>s1
or
HEADLOSS
This is the reduction of pressure in a pipe which may be due to friction
in pipe and pipe fittings* or valves* andean be expressed as a change
in head. Allowable headloss is the difference, in feet of water, be-
tween the tank elecatibn, and the elevation of service connection, plus
the required head atthe service cqrirtectlon. i.e. allowable headloss -
Elev. tank - (elev. service connection + required head)
Example: Given elevation of tank - 750 ft*
elevation service cbhn, ■ 665 ft.
required head (-20 psi) - 46.2 ft. ^
allowable headloss - 750 - (665 + 46.2) * 38.8 ft. of head. \
Note: The required head reconinended by U.N. survey must be at 1 fast
10 psi (13.1 ft) for small water supply systems. For'ipttltl-
storied houses, minimum should be 70 psi (91.7 ft). 20 ps1 (46.2 ft)
is a reasonable figure to work with.
Actual headloss 1s the headloss: which actually occursin pipe and
joints. It roust hot exceed the allowable JjjBad]dss._ The pipes and
joints selected must have a total headloss less than the allowable
headloss. " " ■
6 -188-
CHARACTERISTIC3* 'OF AN ADEQUATE SYSTEM
LESSON NO. 1 \ -
tESSONd^jECtlVE: To outline the general requireiSents for a system
to be qualified as adequate.
TOPIC
INSTRUCTIONAL PROCEDURE
Definiti _ of an
Adequate System ,
Component Farts:
Relative Locations
(*}
Source and Pumping
Facilities
(b) .
Treatment giant
ic)
Storage
Discuss in class and draw out a definition
of "an adequate system*.
Demonstrate how to draw the map and profile
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.
DiscU|s 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 community*
Discuss the various etorage systems and the
effect of location on them.
Ask students to outline what particular
attention be paid to maintaining the quality
of the water.
CHARACTERISTICS OF AN ADEQUATE SYSTEM
LESSON NO. 2
\
LESSON OBJECTIVE:
To determine the relationship between the distribution
system and headlbss in the system; and design a distribution
.system suited to & given community •
TOPIC
Definition of
hcadloss
Relationship. .
between Bead loss
■5 the Oirt$itJU-
n ripes
Relationship
Between the
Coipmunity Layout
arid the Distribu-
tion System
INSTRUCTIONAL PROCEDURE
Define head and headioss.
Demonstrate how to measure head;
Show how to calculate headlbss.
Demonstrate the effect of valves mid
threaded fittings on the water flow in a
pipe.
Show how the above loss may be compensated
for in the plan.
Lecture on how to design a .distribution
system to- fit a jtf veh community^
/
SUPPLEMENTAL MATER I ALS /
RELATED READING
Water in tank
Measuring Scale,
Chart of Headlocs vs.
Pipe Size. Teolcii cf
equivalent pipe icnfti.hr
and valves and fitting
Elevated w/iter source;
long and short pipes*
valves arid joints*
123
-no-
S ECTION 5
CONSTRUCTION TECHNIQUES
OVERVIEW;
The preceding sections have covered the background knowledge that a
trainee must havetb recognize and evaluate sources of water and to plan
the deyilppnterit pf_a_d1str1but1ph aridtfeatmfnt lystetfl. Regardless of _
the planning, a system Is only as good as Its construction allows. Thl?
section covers the techniques needed by the volunteer to adequately con-
struct the system he has designed.
The emphasis of this Instructional material 1s on i doing. _fhi_tra1n|e
should learn by doing, for np amount of lecture can Impart "how% It is
only through doing that the trainee will be able to understand when s for
example, concrete 1s wet enough.
This section covers construction with concrete* and specific products for
building and Installing the major components of a treatment and distri-
bution system.
c
ERIC
SECTION 5 : CONSTRUCTION TECHNIQUES
OBJECTIVE: Develop, purify and distribute water in .a given
community.
TASKS: 1. Develop the selected source to meet the requirements
specified 1h 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_arid_ 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* dH]l,_ahd I bore_a_we]1 1n such a way as to ob-
tain maximum yield from it.*
3. M1* 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 wuVd requife low or
high 1 1 f t-pumps for Intake of water.
7. Build a screen of wlre brother piterlals of desired
mesh around an intake terminal in a pond* lake,
stream, river or any other reservoir to keep put
silt i 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.
-112^
CONSTRUCTION TECHNIQUES (Cont.)
10. Connect various treatment stages i n their proper
order. ;
11. Read and follow ah Instruction manual.
12. Put together a prefabricated . structure j_Us1ng
relhfbrcedcoricrete, painting or spraying the
needed parts, and welding, soldering or riveting
pipes together.
TERMINAL PERFORMANCE TESTS:
1. At_a given J Station develop a water source from
underground water which will meet the water de-
mand of the community.*
2. Siven raw materials required to produce concrete,
mix concrete of aspeclfled 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. In a given distribution system, state where you
would use:
a. Low I1ft_pump_
b. High lift pump
6. Design andbuilda model of an intake terminal
of a system if the source is:
a. Lake or_ppnd
b. River or stream
c. Well or cistern
7. For a given source of water* carry but purity. _
tests and state what kind of treatment the water
requires.
8. Cbhstructslparately the various component parts
of a treatment system and tjest the efficiency It the
j the various treatment stages.
i 9. Given a model treatment plant 1n the labpratpryj
assemble the various .treatment units in order of
j performance (e.g., sedimentation-filtering).
*This skill lis optional, depending on the scope
of the particular training program.
12B
ERIC
-113-
CONSTRUCTION TE CHNIQUES (cont.)
10. * Given a package of all parts of a tank or piimp
(or the respective models) with an accompanying
instruction manual, assemble the parts and test
for proper fittings.^
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_distr1bution 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, db1n several pipe lengths^ using
different methods at each joint* e.g. welding,
riveting, etc.
127
-ii4-
WATER DIST RIBUTION SYST EMS
" CONSTRUCTION TECHNIQUES
SCHEME
The following. sketch shows the major components of a distribution system
that must be planned and constructed. ln_total; this represents a com-
plete water distribution system, Indicating the location of each component
relative to the others;
Source
Pipe ^
Pump
_ House
Storage &
freatment
Pipe
Development
Intake
1) Building house
2) installing pump
1) Cons true ting tank
2} Instilling puri-
fication systems
__ en
ui Z
cj o
k > t—
LU UJ
— as
o o
I- <->
CONCRETE
Fig. 38 Distribution System Layout
The material which is used at almost all stages
…[truncated]