United States
Environmental Protection
Agency
Office of Drinking Water
EPA-570/9-82-004
October 1982
Washington DC 20460
Water
>EPA Manual of
Individual Water
Supply Systems
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Manual of
Individual Water
Supply Systems
ecology and environment inc.
223 W£S,T JAUHS0N, BLVD.
OHtCAOO, H. S060S {312} 663-9415
U.S. Environmental Protection Agency
Office of Drinking Water
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EPA-430/9-74-007
For sale by the Superintendent of Documents. U.S. Government Printing Office
Washington. D.C.. 20402
Washington, D.C., 20402
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Acknowledgment
This manual follows in general the format of its predecessor,
Public Health Service Publication No. 24, prepared by the Joint
Committee on Rural Sanitation.1 The Water Supply Division is
indebted to that committee for the many important contributions
that have been retained.
The special committee charged with responsibility for preparing
this new manual was composed of the following persons:
W. J. Whitsell (Committee Chairman), Ground Water Engineer,
Water Supply Division, Environmental Protection Agency
R. D. Lee, Chief, Surveillance and Technical Assistance, Water
Supply Division, Environmental Protection Agency
E. L. Hockman, Ground Water Engineer, Water Supply
Division, Environmental Protection Agency
D. K. Keech, Chief, Ground Water Quality Control Section,
Michigan State Department of Health
G. F. Briggs, Vice President—Engineering, U. O. P. Johnson
Division, St. Paul, Minn.
Ed Norman, Marvin Norman Drilling Co., Vienna, W. Va.
It is impractical to list here all persons and organizations that have
offered valuable criticisms and suggestions for improvements. Some
30 Federal, State, and private agencies participated in the final
technical review of the completed draft. Their contributions led to
a considerable number of improvements. To all of them, the Water
Supply Division expresses its sincere gratitude.
James H. McDermott, Director
Water Supply Division
The Joint Committee on Rural Sanitation was composed of specialists from the
following agencies: U.S. Department of Agriculture, U.S. Department of Health,
Education, and Welfare, U.S. Department of the Interior, U.S. Coast Guard, Federal
Housing Administration, Veterans' Administration, Tennessee Valley Authority,
Conference of State Sanitary Engineers, Water Pollution Control Federation, Conference
of Municipal Public Health Engineers, American Public Health Association, National Water
Well Association, and Water Systems Council.
iii
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Foreword
Healthful, comfortable living requires the availability of an
adequate supply of good quality water for drinking and domestic
purposes.
Whenever feasible, the consumer will do well to obtain his water
from a public water system in order to enjoy the advantages of
qualified supervision under the control of a responsible public
agency. It is usually his best assurance of an uninterrupted supply
of safe water.
It is not always possible, or economically feasible, to obtain
water from a community water system, and the consumer is then
faced with the need to choose an alternative supply. It is to the
individual or institution faced with this need that this manual is
primarily directed.
This manual is a revision of PHS Publication No. 24, Individual
Water Supply Systems, published in 1962. The revision was begun
by the Bureau of Water Hygiene of the U.S. Public Health Service in
1969. In late 1970, the Bureau's activities and personnel were
transferred by law to the newly created Environmental Protection
Agency (EPA). Work on the manual was completed within EPA.
The Water Supply Division hopes the manual will be useful to
Federal agencies concerned with the development of individual
water supplies, and to State and local health departments, well
drillers, contractors, and individual homeowners as well as to
owners and operators of private and public institutions.
Persons familiar with PHS Publication No. 24 will note that
extensive rewriting and expansion of certain portions have taken
place. This is especially notable in the sections dealing with ground
water and wells. The changes reflect primarily the experiences of
the past 10 years, and especially the advent of new equipment,
methods, and materials. Totally new sections, new illustrations, and
new tables have been added to provide more complete coverage of
the subjects. Color has been used to clarify illustrations. Particular
attention has been paid to the need for keeping recommendations
on construction as practical as possible without compromising
quality and basic principles of sanitation.
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Since a considerable portion of the manual deals with ground
water and wells — over 90 percent of individual systems — the
special committee organized to assemble the new manual was
reinforced appropriately with persons who have had extensive
practical experience in water well construction. Their contributions
were in turn reviewed by individuals and organizations whose work
keeps them in close contact with the field application of practices
recommended in this manual.
Changing times and changing living habits have imposed greater
and greater pollution loads on our environment. It is imperative
that all water systems be constructed in accordance with
recommended practices known to provide effective defenses against
contamination. In addition, each recommendation has been
carefully studied to make sure that it meets the following other
important requirements:
1. It must be practical, yielding results with equipment and
techniques currently available.
2. Its cost must be consistent with the benefits to be expected
from its execution.
3. It must make an important contribution to the useful life of
the installation.
Assistance in the planning of individual water systems usually can
be obtained from State or local health departments. The health
department may in turn suggest other agencies — health
departments and departments of geology and water resources.
These agencies should be the first contacts.
If any question of water rights is involved, the owner should seek
legal advice. Departments of geology and water resources can
frequently advise as to whether water rights are likely to be a
problem.
VI
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Contents
Page
Acknowledgment iii
Foreword v
Part I. Selection of a Water Source 1
II. Ground Water 21
III. Surface Water for Rural Use 61
IV. Water Treatment 73
V. Pumping, Distribution, and Storage 93
Bibliography: List of References on Individual Water Supply Systems 129
Appendixes:
A. Recommended Procedure for Cement Grouting of Wells for
Sanitary Protection 133
B. Bacteriological Quality 137
C. Emergency Disinfection 139
D. Suggested Ordinance 143
Index 151
List of Tables
Table Page
1. Planning guide for water use 15
2. Rates of flow for certain plumbing, household and farm fixtures 17
3. Suitability of well construction methods to different geological conditions 31
4. Steel pipe and casing, standard and standard line pipe 43
5. Quantities of calcium hypochlorite and liquid bleach required for water
well disinfection 52
6. Recommended mechanical analysis of slow sand filter media 75
7. Information on pumps 100
8. Allowance in equivalent length of pipe for friction loss in valves and
threaded fittings 122
vu
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List of Illustrations
Figure Page
1. The hydrologic cycle 2
2. Pumping effects on aquifers 29
3. Dug well with two-pipe jet pump installation 34
4. Different kinds of drive-well points 35
5. Well-point driving methods 36
6. Hand-bored well with driven-well point and "shallow well" jet pump 37
7. Drilled well with submersible pump 40
8. Well seal for jet pump installation 46
9. Well seal for submersible pump installation 47
10. Spring protection 57
11. Yield of impervious catchment area 63
12. Cistern 65
13. Pond 68
14. Schematic diagram of pond water-treatment system 69
15. Exploded view of submersible pump 95
16. "Over-the-well" jet pump installation 97
17. Determining recommended pump capacity 99
18. Components of total operating head in well pump installations 102
19. Vertical (line shaft) turbine pump mounted on well casing 105
20. Pumphouse 108
21. Clamp-on pitless adapter for submersible pump installation Ill
22. Pitless unit with concentric external piping for jet pump installation 112
23. Weld-on pitless adapter with concentric external piping for "shallow well"
purnp installation 113
24. Pitless adapter with submersible pump installation for basement storage 114
25. Pitless adapter and unit testing equipment 117
26. Head loss versus pipe size 121
27. Typical concrete reservoir 127
28. Typical valve and box, manhole covers, and piping installations 128
VTll
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Parti
Selection of a
Water Source
The planning of an individual water supply system requires a
determination of the quality of the water and available sources. In
addition, it is desirable for one to have a basic knowledge of water
rights and the hydrological, geological, chemical, biological, and
possible radiological factors affecting the water. These factors are
usually interrelated because of the continuous circulation of the
water or water vapor from the oceans to the air, over the surface of
the land and underground, and back to the oceans. This circulation
is called hydrologic cycle. (See fig. 1.)
RIGHTS TO THE USE OF WATER
The right of an individual to use of water for domestic, irrigation,
or other purposes varies in different States. Some water rights stem
from ownership of the land bordering or overlying the source, while
others are acquired by a performance of certain acts required by
law.
There are three basic types of water rights. They are:
Riparian.-Rights that are acquired together with title to the
land bordering or overlying the source of water.
Appropriative.— Rights that are acquired by following a specific
legal procedure.
Prescriptive.—Rights that are acquired by diverting and putting
to use, for a period specified by statute, water to which
other parties may or may not have prior claims. The
procedure necessary to obtain prescriptive rights must
conform with the conditions established by the water rights
laws of individual States.
When there is any question regarding the right to the use of
water, the property owner should consult the appropriate authority
in his State and clearly establish his rights to its use.
SOURCES OF WATER SUPPLY
At some time in its history, water resided in the oceans. By
evaporation, moisture is transferred from the ocean surface to the
atmosphere, where the winds carry the moisture-laden air over
landmasses. Under certain conditions, this water vapor condenses to
form clouds, which release their moisture as precipitation in the
form of rain, hail, sleet, or snow.
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When rain falls toward the earth, a part may evaporate and return
immediately to the atmosphere. Precipitation in excess of the
amount that wets a surface or supplies evaporation requirements is
available as a potential source of water supply.
Ground Water
A part of the precipitation may infiltrate into the soil. (See fig.
1.) This water replenishes the soil moisture or is used by growing
plants and returned to the atmosphere by transpiration. Water that
drains downward below the root zone finally reaches a level at
which all of the openings or voids in the earth's materials are filled
with water. This zone is known as the "zone of saturation." Water
in the zone of saturation is referred to as "ground water." The
upper surface of the zone of saturation, if not confined by
impermeable material, is called the "water table." When an
overlying impermeable formation confines the water in the zone of
saturation under a pressure greater than atmospheric pressure, the
ground water is under artesian pressure. The name "artesian" comes
from the ancient province of Artesium in France, where in the days
of the Romans water flowed to the surface of the ground from a
well. Not all water from wells that penetrate artesian formations
flows above the surface of the land. For a well to be artesian, the
water in the well must stand above the top of the aquifer. An
aquifer, or water-bearing formation, is an underground layer of
permeable rock or soil that permits the passage of water.
The porous material just above the water table may contain water
by capillarity in the smaller void spaces. This zone is referred to as
the "capillary fringe." It is not a source of supply since the water
held will not drain freely by gravity.
Because of the irregularities in underground deposits and in
surface topography, the water table occasionally intersects the
surface of the ground or the bed of a stream, lake, or ocean. As a
result, ground water moves to these locations and out of the aquifer
or ground water reservoir. Thus, ground water is continually moving
within the aquifer even though the movement may be slow. The
water table or artesian pressure surface slopes from areas of
recharge to areas of discharge. The pressure differences represented
by these slopes cause the flow of ground water within the aquifer.
At any point the slope is a reflection of the rate of flow and
resistance to movement of water through the saturated formation.
Seasonal variations in the supply of water to the underground
reservoir cause considerable changes in the elevation and slope of
the water table and artesian pressure level.
Wells
A well can be used to extract water from the ground water
reservoir. Pumping will cause a lowering of the water table near the
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well. If pumping continues at a rate that exceeds the rate at which
the water may be replaced by the water-bearing formations, the
sustained yield of the well is exceeded. If wells extract water from
an aquifer over a period of time at a rate such that the aquifer will
become depleted or bring about other undesired results, then the
"safe yield" of the aquifer is exceeded. Under these conditions, salt-
water encroachment may occur where wells are located near the
seashore or other surface or underground saline waters.
Springs
An opening in the ground surface from which ground water flows
is a spring. Water may flow by force of gravity (from water-table
aquifers), or be forced out by artesian pressure. The flow from a
spring may vary considerably. When the water-table or artesian
pressure fluctuates, so does the flow of springs. For further
discussion, see part II.
Surface Water
Precipitation that does not enter the ground through infiltration
or is not returned to the atmosphere by evaporation flows over the
ground surface and is classified as direct runoff. Direct runoff is
water that moves over saturated or impermeable surfaces, and in
stream channels or other natural or artificial storage sites. The dry
weather (base) flow of streams is derived from ground water or
snowmelt.
In some areas, a source of water for individual development is the
rainfall intercepted by roof surfaces on homes, barns, or other
buildings. Water from such impermeable surfaces can be collected
and stored in tanks called cisterns. In some instances, natural
ground surfaces can be conditioned to make them impermeable.
This conditioning will increase runoff to cisterns or large artificial
storage reservoirs, thereby reducing loss by infiltration into the
ground.
Runoff from ground surfaces may be collected in either natural
or artificial reservoirs. A portion of the water stored in surface
reservoirs is lost by evaporation and from infiltration to the ground
water table from the pond bottom. Transpiration from vegetation
in and adjacent to ponds constitutes another means of water loss.
Ground and Surface Water
Ground water may become surface water at springs or at
intersections of a water body and a water table. During extended
dry periods, stream flows consist largely of water from the
ground water reservoir. As the ground water reservoir is drained by
the surface stream, the flow will reach a minimum or may cease
altogether. It is important in evaluating stream and spring supplies
to consider seasonal fluctuations in flow.
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Snow
Much of the snow falling on a water shed is kept in storage on the
ground surface until temperatures rise above freezing. In the
mountainous areas of the western United States, snow storage is an
important source of water supply through much of the normal
irrigation season. Measures taken to increase the snowpack and
reduce the melt rate are usually beneficial to individual water
supply systems in these areas.
QUALITY OF WATER
Precipitation in the form of rain, snow, hail, or sleet contains
very few impurities. It may contain trace amounts of mineral
matter, gases, and other substances as it forms and falls through the
earth's atmosphere. The precipitation, however, has virtually no
bacterial content.
Once precipitation reaches the earth's surface, many
opportunities are presented for the introduction of mineral and
organic substances, micro-organisms, and other forms of pollution
(contamination).1 When water runs over or through the ground
surface, it may pick up particles of soil. This is noticeable in the
water as cloudiness or turbidity. It also picks up particles of organic
matter and bacteria. As surface water seeps downward into the soil
and through the underlying material to the water table, most of the
suspended particles are filtered out. This natural filtration may be
partially effective in removing bacteria and other particulate
materials; however, the chemical characteristics of the water may
change and vary widely when it comes in contact with mineral
deposits. Chemical and bacteriological analyses may be performed
by a State or local health department or by a commercial
laboratory.
The widespread use of synthetically produced chemical
compounds, including pesticides and insecticides, has caused a
renewed interest in the quality of water. Many of these materials
are known to be toxic and others have certain undesirable
characteristics which interfere with the use of the water even when
present in relatively small concentrations. In recent years instances
of water pollution have been traced to a sewage or waste water
source containing synthetic detergents.
Substances that alter the quality of water as it moves over or
below the surface of the earth may be classified under four major
headings.
Pollution as used in this manual means the presence in water of any foreign substances
(organic, inorganic, radiological, or biological) which tend to lower its quality to a point
that it constitutes a health hazard or impairs the usefulness of the water. Contamination,
where used in this manual, has essentially the same meaning.
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1. Physical. Physical characteristics relate to the quality of
water for domestic use and are usually associated with
the appearance of water, its color or turbidity,
temperature, taste, and odor in particular.
2. Chemical. Chemical differences between waters are
sometimes evidenced by their observed reactions, such as
the comparative performance of hard and soft waters in
laundering.
3. Biological. Biological agents are very important in their
relation to public health and may also be significant in
modifying the physical and chemical characteristics of
water.
4. Radiological. Radiological factors must be considered in
areas where there is a possibility that the water may have
come in contact with radioactive substances.
Consequently, in the development of an individual water supply
system, it is necessary to examine carefully all the factors that
might adversely affect the intended use of a water supply source.
Physical Characteristics
The water as used should be free from all impurities that are
offensive to the sense of sight, taste, or smell. The physical
characteristics of the water include turbidity, color, taste and odor,
temperature, and foamability.
Turbidity. The presence of suspended material such as clay, silt,
finely divided organic material, plankton, and other inorganic
material in water is known as turbidity. Turbidities in excess of 5
units are easily detectable in a glass of water, and are usually
objectionable for esthetic reasons.
Clay or other inert suspended particles in drinking water may not
adversely affect health, but water containing such particles may
require treatment to make it suitable for its intended use. Following
a rainfall, variations in the ground water turbidity may be
considered an indication of surface or other introduced pollution.
Color. Dissolved organic material from decaying vegetation and
certain inorganic matter cause color in water. Occasionally,
excessive blooms of algae or the growth of aquatic micro-organisms
may also impart color. While color itself is not usually objectionable
from the standpoint of health, its presence is esthetically
objectionable and suggests that the water needs appropriate
treatment.
Taste and Odor. Taste and odor in water can be caused by
foreign matter such as organic compounds, inorganic salts, or
dissolved gases. These materials may come from domestic,
agricultural, or natural sources. Acceptable waters should be free
from any objectionable taste or odor at point of use. Knowledge
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concerning the chemical quality of a water supply source is
important in order to determine what treatment, if any, is required
to make the water acceptable for domestic use.
Temperature. The most desirable drinking waters are
consistently cool and do not have temperature fluctuations of more
than a few degrees. Ground water and surface water from
mountainous areas generally meet these criteria. Most individuals
find that water having a temperature between 50° and 60° F is most
palatable.
Foamability. Since 1965 the detergent formulations have been
changed to eliminate alkyl benzene sulfonate (ABS), which was
very slowly degraded by nature. The more rapidly biodegradable
linear alkylate sulfonate (LAS) has been substituted in most
detergents. Even LAS is not degraded very rapidly in the absence of
oxygen — a condition that exists in cesspools and some septic tank
tile fields.
Foam in water is usually caused by concentrations of detergents
greater than 1 milligram per liter. While foam itself is not
hazardous, the user should understand that if enough detergent is
reaching a water supply to cause a noticeable froth to appear on a
glass of water, other possibly hazardous materials of sewage origin
are also likely to be present.
Chemical Characteristics
The nature of the rocks that form the earth's crust affects not
only the quantity of water that may be recovered but also its
characteristics. As surface water seeps downward to the water table,
it dissolves portions of the minerals contained by soils and rocks.
Ground water, therefore, usually contains more dissolved minerals
than surf ace water.
The chemical characteristics of water in a particular locality can
sometimes be predicted from analyses of adjacent water sources.
These data are often available in published reports of the U.S.
Geological Survey or from Federal, State, and local health,
geological, and water agencies. In the event that the information is
not available, a chemical analysis of the water source should be
made. Some State health and geological departments, as well as
State colleges, and many commercial laboratories have the facilities
and may be able to provide this service.
Information that can be obtained from a chemical analysis is -
• The possible presence of harmful or disagreeable substances
• The potential for the water to corrode parts of the water
system
• The tendency for the water to stain fixtures and clothing
The size of sample required and the method of collection should be
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in accordance with recommendations of the facility making the
analysis.
The following is a discussion of the chemical characteristics of water
based on the limits recommended by the U.S. Environmental Protection
Agency.2
Toxic Substances. Water may contain toxic substances in
solution. If analysis of the water supply shows that these substances
exceed the following concentrations, the supply should not be
used:
Substance
Arsenic (As)
Barium (Ba)
Cadmium (Cd)
Chromium (Cr+6)
Milligrams
per literl
0 05
1.00
01
.05
Substance
Fluoride (F)
Lead (Pb)
Mercury
Selenium (Se)
Silver (Ag)
Milligrams
per literl*
(2*1
005
0002
01
05
1 The term "milligrams per liter (mg/8)" replace
water, the two terms are essentially equivalent.
2* See following table.
the term "parts per million (ppm)." For
The maximum concentrations of fluoride depend on the annual
average maximum daily air temperature, as shown in the following
table, because the temperature influences water intake:
Annual average of maximum
daily aii temperature
Maximum allowable
fluoride
concentration (mg/C)
50.0°-53 7°
53.8°-58.3°
58.4°-63 8°
63.9°-70.6°
70.7°-79 2°
79.3°-90.5°
p
2.4
2 2
2.0
1.8
1.6
1.4
Chlorides. Most waters contain some chloride in solution. The
amount present can be caused by the leaching of marine
sedimentary deposits, by pollution from sea water, brine, or
industrial and domestic wastes. Chloride concentrations in excess of
about 250 mg/£ usually produce a noticeable taste in drinking
water. In areas where the chloride content is higher than 250 mg/C
and all other criteria are met, it may be necessary to use a water
source that exceeds this limit.
An increase in chloride content in water may indicate possible
pollution from sewage sources, particularly if the normal chloride
content is known to be low.
2 U.S. Environmental Protection Agency, Office of Drinking Water, "National Interim
Primary Drinking Water Regulations," December 1975. U.S. Environmental Protection
Agency, Washington, D.C. 20460
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Copper. Copper is found in some natural waters, particularly in
areas where these ore deposits have been mined.
Excessive amounts of copper can occur in corrosive water that
passes through copper pipes. Copper in small amounts is not
considered detrimental to health, but will impart an undesirable
taste to the drinking water. For this reason, the recommended limit
for copper is 1.0 mg/C.
Fluorides. In some areas water sources contain natural fluorides.
Where the concentrations approach optimum levels, beneficial
health effects have been observed. In such areas the incidence of
dental caries has been found to be below the rate in areas without
natural fluorides.4 The optimum fluoride level for a given area
depends upon air temperature, since that is what primarily
influences the amount of water people drink. Optimum
concentrations from 0.7 to 1.2 mg/C are recommended. Excessive
fluorides in drinking water supplies may produce fluorosis
(mottling) of teeth, which increases as the optimum fluoride level is
exceeded. The State or local health departments, therefore, should
be consulted for their recommendations.
Iron. Small amounts of iron are frequently present in water
because of the large amount of iron present in the soil and because
corrosive water will pick up iron from pipes. The presence of iron in
water is considered objectionable because it imparts a brownish
color to laundered goods and affects the taste of beverages such as
tea and coffee. Recent studies indicate that eggs spoil faster when
washed in water containing iron in excess of 10 mg/C. The
recommended limit for iron is 0.3 mg/C.
Lead. A brief or prolonged exposure of the body to lead can be
seriously injurious to health. Prolonged exposure to relatively small
quantities may result in serious illness or death. Lead taken into the
body in quantities in excess of certain relatively low "normal"
limits is a cumulative poison. A maximum concentration of 0.05
mg/C of lead in water must not be exceeded. Excessive lead may
occur in the source water, but the usual cause of excessive lead is
corrosive water in contact with lead-painted roofs or the use of lead
pipes. These conditions must be corrected to provide a safe water
supply.
Manganese. There are two reasons for limiting the concentration
of manganese in drinking water: (1) to prevent esthetic and
economic damage, and (2) to avoid any possible physiological
effects from excessive intake. The domestic user finds that
manganese produces a brownish color in laundered goods, and
impairs the taste of beverages, including coffee and tea. The
recommended limit for manganese is 0.05 mg/C.
It is a known fact that the addition of about 1 mg/C of fluoride to water supplies will
help to prevent tooth decay in children. Some natural water supplies already contain
amounts of fluoride that exceed the recommended optimum concentrations.
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Nitrates. Nitrate (NO3) has caused methemoglobinemia (infant
cyanosis or "blue baby disease") in infants who have been given
water or fed formulas prepared with water having high nitrates. A
domestic water supply should not contain nitrate concentrations in
excess of 45 mg/£ (10 mg/£ expressed as nitrogen). Nitrates in
excess of normal concentrations, often in shallow wells, may be an
indication of seepage from livestock manure deposits. In some
polluted wells, nitrite will also be present in concentrations greater
than 1 mg/£ and is even more hazardous to infants. When the
presence of high nitrite concentration is suspected the water should
not be used for infant feeding. The nitrate concentration should be
determined, and if excessive, advice should be obtained from health
authorities about the suitability of using the water for drinking by
anyone.
Pesticides. Careless use of pesticides can contaminate water
sources and make the water unsuitable for drinking. Numerous
cases have been reported where individual wells have been
contaminated when the house was treated for termite control. The
use of pesticides near wells is not recommended.
Sodium. When it is necessary to know the precise amount of
sodium present in a water supply, a laboratory analysis should be
made. When home water softeners utilizing the ion-exchange
method are used, the amount of sodium will be increased. For this
reason, water that has been softened should be analyzed for sodium
when a precise record of individual sodium intake is recommended.
For healthy persons, the sodium content of water is unimportant
because the intake from salt is so much greater, but for persons
placed on a low-sodium diet because of heart, kidney, or circulatory
ailments or complications of pregnancy, sodium in water must be
considered. The usual low-sodium diets allow for 20 mg/£ sodium in
the drinking water. When this limit is exceeded, such persons should
seek a physician's advice on diet and sodium intake.
Sulfates. Waters containing high concentrations of sulfate caused
by the leaching of natural deposits of magnesium sulfate (Epsom
salts) or sodium sulfate (Glauber's salt) may be undesirable because
of their laxative effects. Sulfate content should not exceed 250
mg/C.
Zinc. Zinc is found in some natural waters, particularly in areas
where these ore deposits have been mined. Zinc is not considered
detrimental to health, but it will impart an undesirable taste to
drinking water. For this reason, the recommended limit for zinc is
5.0 mg/fi.
Serious surface and ground water pollution problems have
developed from existing and abandoned mining operations. Among
the worst are those associated with coalmine operations, where
heavy concentrations of iron, manganese, sulfates, and acids have
10
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resulted from the weathering and leaching of minerals (pyrites).
Chemical Terms
Alkalinity. Alkalinity is imparted to water by bicarbonate,
carbonate, or hydroxide components. The presence of these
compounds is determined by standard methods involving titration
with various indicator solutions. Knowledge of the alkalinity
components is useful in the treatment of water supplies.
Hardness. Hard water and soft water are relative terms. Hard
water retards the cleaning action of soaps and detergents, causing an
expense in the form of extra work and cleaning agents.
Furthermore, when hard water is heated it will deposit a hard scale
(as in a kettle, heating coils, or cooking utensils) with a consequent
waste of fuel.
Calcium and magnesium salts, which cause hardness in water
supplies, are divided into two general classifications: carbonate or
temporary hardness and noncarbonate or permanent hardness.
Carbonate or temporary hardness is so called because heating the
water will largely remove it. When the water is heated, bicarbonates
break down into insoluble carbonates that precipitate as solid
particles which adhere to a heated surface and the inside of pipes.
Noncarbonate or permanent hardness is so called because it is not
removed when water is heated. Noncarbonate hardness is due
largely to the presence of the sulfates and chlorides of calcium and
magnesium in the water.
pH. pH is a measure of the hydrogen ion concentration in water.
It is also a measure of the acid or alkaline content. pH values range
from 0 to 14, where 7 indicates neutral water; values less than 7,
increasing acidity; and values greater than 7, increasing alkalinity.
The pH of water in its natural state often varies from 5.5 to 9.0.
Determination of the pH value assists in the control of corrosion,
the determination of proper chemical dosages, and adequate control
of disinfection.
Biological Factors
Water for drinking and cooking purposes must be made free from
disease-producing organisms. These organisms include bacteria,
protozoa, virus, and helminths (worms).
Contamination of Water Supplies
Some organisms that cause disease in man originate with the fecal
discharges of infected individuals. It is seldom practical to monitor
and control the activities of human disease carriers. For this reason,
it is necessary to exercise precautions against contamination of a
normally safe water source or to institute treatment methods which
will produce a safe water.
Unfortunately, the specific disease-producing organisms present
11
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in water are not easily identified. The techniques for comprehensive
bacteriological examination are complex and time consuming. It has
been necessary to develop tests that indicate the relative degree of
contamination in terms of an easily defined quantity. The most
widely used test involves estimation of the number of bacteria of
the coliform group, which is always present in fecal wastes and
outnumbers disease-producing organisms. The coliform group
normally inhabits the intestinal tract of man, but is also found in
most domestic animals and birds, as well as certain wild species.
Bacteriological Quality
The Public Health Service Drinking Water Standards have
established limits for the mean concentration of coliform bacteria
in a series of water samples and the frequency at which
concentrations may exceed the mean. The results are expressed
either in terms of a direct count of bacteria per unit volume - if the
membrane filter (MF) procedure is used — or in terms of the "most
probable number" (MPN). This latter term is an estimate based on
mathematical formulas of probability.
The recommended standards for drinking water are roughly
equivalent to restricting the coliform concentration to not more
than one organism for each 100 milliliters of water.5
Application of the Public Health Service Drinking Water
Standards to individual water supplies is difficult due to the low
frequency with which samples can be properly collected and
examined. Bacteriological examinations indicate the presence or
absence of contamination in the collected sample only, and are
indicative of quality only at the time of collection. A sample
positive for coliforms is a good indication that the source may have
been contaminated by surface washings or fecal material. On the
other hand, a negative result cannot be considered assurance of a
continuously safe supply unless the results of a thorough sanitary
survey of the surrounding area, together with subsequent negative
samples, support this position.
Collection of Samples for Bacteriological Examination
For a reliable indication of the bacteriological safety of an
individual water supply, the owner should depend on the
experience of qualified public health personnel. Special precautions
are necessary in the collection of water samples, and proper training
and experience are essential in evaluating the analytical results.
Before a sample is collected, the examining facility should be
contacted to obtain its recommendations. In the event that a
procedure is not given, one should follow the suggestions found in
appendix B.
5One hundred milliliters is about one-half cup in volume.
12
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Other Biological Factors
Certain forms of aquatic vegetation and microscopic animal life
in natural water may be either stimulated or retarded in their
growth cycles by physical, chemical, or biological factors. For
example, the growth of algae, minute green plants usually found
floating in surface water, is stimulated by light, heat, nutrients such
as nitrogen and phosphorus, and the presence of carbon dioxide as a
product of organic decomposition. Their growth may, in turn, be
retarded by changes in pH (measure of acidity), the presence of
inorganic impurities, excessive cloudiness or darkness, temperature,
and the presence of certain bacterial species.
Continuous cycles of growth and decay of algal cell material may
result in the production of noxious byproducts that may adversely
affect the quality of a water supply. The same general statements
may be made regarding the growth cycles of certain nonpathogenic
bacteria or microcrustacea that inhabit natural waters.
A water source should be as free from biological activity as
possible. Biological activity can be avoided or kept to a minimum by:
1. Selecting water sources that do not normally support much
plant or animal life.
2. Protecting the supply against subsequent contamination by
biological agents.
3. Minimizing entrance of fertilizing materials, such as organic
and nutrient minerals.
4. Controlling the light and temperature of stored water.
5. Providing treatment for the destruction of biologic life or its
byproducts.
Radiological Factors
The development and use of atomic energy as a power source and
mining of radioactive materials have made it necessary to establish
limiting concentrations for the intake into the body of radioactive
substances, including drinking water.
The effects of human exposure to radiation or radioactive
materials are viewed as harmful and any unnecessary exposure
should be avoided. The concentrations of radioactive materials
specified in the current Public Health Service Drinking Water
Standards are intended to limit the human intake of these
substances so that the total radiation exposure of any individual
will not exceed those defined in the Radiation Protection Guides
recommended by the Federal Radiation Council. Man has always
been exposed to natural radiation from water, food, and air. The
amount of radiation to which the individual is normally exposed
varies with the amount of background radioactivity. Water of high
radioactivity is unusual. Nevertheless it is known to exist in certain
areas, either from natural or manmade sources.
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Radiological data indicating both background and other forms of
radioactivity in an area may be available in publications of the U.S.
Environmental Protection Agency, U.S. Public Health Service, U.S.
Geological Survey, or from Federal, State, or local agencies. For
information or recommendations on specific problems, the
appropriate agency should be contacted.
QUANTITY OF WATER
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
continuing demands over critical periods when surface
flows are low and ground water tables are at minimum
elevations and
2. For purposes of estimating quantities of stored water that
would sustain demands during these critical periods.
The peak demand rates must be estimated in order to determine
plumbing and pipe sizing, pressure losses, and storage requirements
necessary to supply sufficient water during periods of peak water
demand.
Average Daily Water Use
Many factors influence water use for a given system. For
example, the mere fact that water under pressure is available
stimulates its use for watering lawns and gardens, for washing
automobiles, for operating air-conditioning equipment, and for
performing many other utility activities at home and on the farm.
Modern kitchen and laundry appliances, such as food waste
disposers and automatic dishwashers, contribute to a higher total
water use and tend to increase peak demands. Since water
requirements will influence all features of an individual
development or improvement, they must figure prominently in plan
preparation. Table 1 presents a summary of average water use as a
guide in preparing estimates, with local adaptations where
necessary.
Peak Demands
The rate of water use for an individual water system will vary
directly with domestic activity in the home or with the operational
farm program. Rates are generally highest in the home near
mealtimes, during midmorning laundry periods, and shortly before
bedtime. During the intervening daytime hours and at night, water
use may be virtually nil. Thus, the total amount of water used by a
household may be distributed over only a few hours of the day,
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TABLE 1. - Planning guide for water use
Types of establishments
Gallons
per day
Airports (per passenger) 3-5
Apartments, multiple family (per resident) 60
Bath houses (per bather) 10
Camps:
Construction, semipermanent (per worker) 50
Day with no meals served (per camper) 15
Luxury (per camper) 100-150
Resorts, day and night, with limited plumbing (per camper) 50
Tourist with central bath and toilet facilities (per person) 35
Cottages with seasonal occupancy (per resident) 50
Courts, tourist with individual bath units (per person) 50
Clubs:
Country (per resident member) 100
Country (per nonresident member present) 25
Dwellings:
Boardinghouses (per boarder) 50
Additional kitchen requirements for nonresident boarders 10
Luxury (per person) 100-150
Multiple-family apartments (per resident) 40
Rooming houses (per resident) 60
Single family (per resident) 50-75
Estates (per resident) 100-150
Factories (gallons per person per shift) 15-35
Highway rest area (per person) 5
Hotels with private baths (2 persons per room) 60
Hotels without private baths (per person) 50
Institutions other than hospitals (per person) 75-125
Hospitals (per bed) 250-400
Laundries, self-serviced (gallons per washing, i.e., per customer) 50
Livestock (per animal):
Cattle (drinking) 12
Dairy (drinking and servicing) 35
Goat (drinking) 2
Hog (drinking) 4
Horse (drinking) 12
Mule (drinking) 12
Sheep (drinking) 2
Steer (drinking) 12
Motels with bath, toilet, and kitchen facilities (per bed space) 50
With bed and toilet (per bed space) 40
Parks:
Overnight with flush toilets (per camper) 25
Trailers with individual bath units, no sewer connection (per trailer) • • • 25
Trailers with individual baths, connected to sewer (per person) 50
Picnic:
With bathhouses, showers, and flush toilets (per picnicker) 20
With toilet facilities only (gallons per picnicker) 10
Poultry:
Chickens (per 100) 5-10
Turkeys (per 100) 10-18
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TABLE 1. — Planning guide for water use — Continued
Types of establishments
Gallons
per day
Restaurants with toilet facilities (per patron)
Without toilet facilities (per patron)
With bars and cocktail lounge (additional quantity per patron)
Schools:
Boarding (per pupil)
Day with cafeteria, gymnasiums, and showers (per pupil) • •
Day with cafeteria but no gymnasiums or showers (per pupil)
Day without cafeteria, gymnasiums, or showers (per pupil)
Service stations (per vehicle)
Stores (per toilet room)
Swimming pools (per swimmer)
Theaters:
Drive-in (per car space)
Movie (per auditorium seat)
Workers:
Construction (per person per shift)
Day (school or offices per person per shift)
7-10
2'/2-3
2
75-100
25
20
15
10
400
10
5
5
50
15
during which the actual use is much greater than the average rate
determined from Table 1.
Simultaneous operation of several plumbing fixtures will
determine the maximum peak rate of water delivery for the home
water system. For example, a shower, an automatic dishwasher, a
lawn-sprinkler system, and a flush valve toilet all operated at the
same time would probably produce a near-critical peak. It is true
that not all of these facilities are usually operated together; but if
they exist on the same system, there is always a possibility that a
critical combination may result, and for design purposes this
method of calculation is sound. Table 2 summarizes the rate of flow
which would be expected for certain household and farm fixtures.
Special Water Considerations
Lawn Sprinkling. The amount of water required for lawn
sprinkling depends upon the size of the lawn, type of sprinkling
equipment, climate, soil, and water control. In dry or arid areas the
amount of water required may equal or exceed the total used for
domestic or farmstead needs. For estimating purposes, a rate of
approximately l/2 inch per hour of surface area is reasonable. This
amount of water can be applied by sprinkling 30 gallons of water
per hour over each 100 square feet.
Example:
1000
X 30 = 300 gallons per hour or 5 gpm
A lawn of 1,000 square feet would require 300 gallons per hour.
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TABLE 2. — Rates of flow for certain plumbing, household, and farm fixtures
Location
Ordinary basin faucet
Self-closing basin faucet ... ....
Sink faucet 3/8 inch
Sink faucet, 1/2 inch
Bathtub faucet
Laundry tub faucet 1/2 inch
Shower
Ball-cock for closet
Flush valve for closet . .
Garden hose (50 ft 3/4-inch sill cock)
Garden hose (50 ft 5/8-inch outlet) ...
Drinking fountains
Flow pressure
-pounds per
square inch
(psi)
8
8
8
8
8
8
8
8
15
15
30
15
15
30
Flow rate-
gallons per
minute (gpm)
2.0
2 5
4 5
4.5
6.0
5 0
5.0
3.0
2 15-40
15 0
5 0
3.33
.75
40 0
1 Flow pressure is the pressure in the supply near the faucet or water outlet while the
faucet or water outlet is wide open and flowing.
2Wide range due to variation in design and type of closet flush valves.
When possible, the water system should have a minimum capacity
of 500-600 gallons per hour. A water system of this size may be
able to operate satisfactorily during a peak demand. Peak flows can
be estimated by adding lawn sprinkling to peak domestic flows but
not to fire flows.
Fire Protection. In areas of individual water supply systems,
effective firefighting depends upon the facilities provided by the
property owner. The National Fire Protection Association has
prepared a report which outlines and describes ways to utilize
available water supplies.6
The most important factors in successful firefighting are early
discovery and immediate action. For immediate protection,
portable fire extinguishers are desirable. Such first-aid protection is
designed only for the control of fires in the early stage; therefore, a
water supply is desirable as a second line of defense.
The use of gravity water supplies for firefighting presents certain
basic problems. These include (1) the construction of a dam, farm
pond, or storage tank to hold the water until needed, and (2) the
determination of the size of pipeline installed from the supply. The
National Fire Protection Association, "Water Supply Systems for Rural Fire Protection,"
National Fire Codes, vol. 8 (Boston, 1969).
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size of the pipe is dependent upon two factors: (1) the total fall or
head from the point of supply to the point of use and (2) the length
of pipeline required.
A properly constructed well tapping a good aquifer can be a
dependable source for both domestic use and fire protection. If the
well is to be relied upon for fire protection without supplemental
storage, it should demonstrate, by a pumping test, minimum
capacity of 8 to 10 gallons per minute continuously for a period of
2 hours during the driest time of the year.
A more dependable installation results when motor, controls, and
powerlines are protected from fire. A high degree of protection is
achieved when all electrical elements are located outside at the well,
and there is a separate powerline bypassing other buildings.
There are numerous factors determining the amount of fire
protection that should be built into a water system. Publications of
the National Fire Protection Association7 provide more
information on this subject.
The smallest individual pressure systems commercially available
provide about 210 gallons per hour (3J/2 gallons per minute).
While this capacity will furnish a stream, through an ordinary
garden hose, of some value in combating incipient fires or in
wetting down adjacent buildings, it cannot be expected to be
effective on a fire that has gained any headway. When such systems
are already installed, connections and hose should be provided.
When a new system is being planned or a replacement of equipment
made, it is urged that a capacity of at least 500 gallons an hour
(8-1/3 gallons per minute) be specified and the supply increased to
meet this demand. If necessary, storage should be added. The
additional cost for the larger unit necessary for fire protection is
partially offset by the increased quantities of water available for
other uses.
SANITARY SURVEY
The importance of a sanitary survey of water sources cannot be
overemphasized. With a new supply, the sanitary survey should be
made in conjunction with the collection of initial engineering data
covering the development of a given source and its capacity to meet
existing and future needs. The sanitary survey should include the
detection of all health hazards and the assessment of their present
and future importance. Persons trained and competent in public
health engineering and the epidemiology of waterborne diseases
should conduct the sanitary survey. In the case of an existing
supply, the sanitary survey should be made at a frequency
compatible with the control of the health hazards and the
maintenance of a good sanitary quality.
7Ibid.
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The information furnished by the sanitary survey is essential to
complete interpretation of bacteriological and frequently the
chemical data. This information should always accompany the
laboratory findings. The following outline covers the essential
factors which should be investigated or considered in a sanitary
survey. Not all of the items are pertinent to any one supply and, in
some cases, items not in the list would be important additions to
the survey list.
Ground Water Supplies
a. Character of local geology; slope of ground surface.
b. Nature of soil and underlying porous strata; whether clay,
sand, gravel, rock (especially porous limestone);
coarseness of sand or gravel; thickness of water-bearing
stratum, depth to water table; location, log, and
construction details of local wells in use and
abandoned.
c. Slope of water table, preferably as determined from
observational wells or as indicated, presumptively but
not certainly, by slope of ground surface.
d. Extent of drainage area likely to contribute water to the
supply.
e. Nature, distance, and direction of local sources of
pollution.
f. Possibility of surface-drainage water entering the supply
and of wells becoming flooded; methods of protection.
g. Methods used for protecting the supply against pollution
by means of sewage treatment, waste disposal, and the
like.
h. Well construction:
1. Total depth of well.
2. Casing: diameter, wall thickness, material, and length
from surface.
3. Screen or perforations: diameter, material,
construction, locations, and lengths.
4. Formation seal: material (cement, sand, bentonite,
etc.), depth intervals, annular thickness, and
method of placement.
i. Protection of well at top: presence of sanitary well seal,
casing height above ground, floor, or flood level,
protection of well vent, protection of well from
erosion and animals.
j. Pumphouse construction (floors, drains, etc.), capacity of
pumps, drawdown when pumps are in operation.
k. Availability of an unsafe supply, usable in place of normal
supply, hence involving danger to the public health.
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1. Disinfection: equipment, supervision, test kits, or other
types of laboratory control.
Surface-Water Supplies
a. Nature of surface geology: character of soils and rocks.
b. Character of vegetation, forests, cultivated and irrigated
land, including salinity, effect on irrigation water, etc.
c. Population and sewered population per square mile of
catchment area.
d. Methods of sewage disposal, whether by diversion from
watershed or by treatment.
e. Character and efficiency of sewage-treatment works on
watershed.
f. Proximity of sources of fecal pollution to intake of water
supply.
g. Proximity, sources, and character of industrial wastes, oil
field brines, acid mine waters, etc.
h. Adequacy of supply as to quantity.
i. For lake or reservoir supplies: wind direction and velocity
data, drift of pollution, sunshine data (algae).
j. Character and quality of raw water: coliform organisms
(MPN), algae, turbidity, color, objectionable mineral
constituents.
k. Nominal period of detention in reservoir or storage basin.
1. Probable minimum time required for water to flow from
sources of pollution to reservoir and through reservoir
intake.
m. Shape of reservoir, with reference to possible currents of
water, induced by wind or reservoir discharge, from
inlet to water-supply intake.
n. Protective measures in connection with the use of
watershed to control fishing, boating, landing of
airplanes, swimming, wading, ice cutting, permitting
animals on marginal shore areas and in or upon the
water, etc.
o. Efficiency and constancy of policing.
p. Treatment of water: kind and adequacy of equipment;
duplication of parts; effectiveness of treatment;
adequacy of supervision and testing; contact period
after disinfection; free chlorine residuals carried.
q. Pumping facilities: pumphouse, pump capacity and
standby units, storage facilities.
20
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Part II
Ground Water
ROCK FORMATIONS AND THEIR WATER-BEARING
PROPERTIES
The rocks that form the crust of the earth are divided into three
classes:
1. Igneous. Rocks that are derived from the hot magma deep
in the earth. They include granite and other coarsely
crystalline rocks, dense igneous rocks such as occur in
dikes and sills, basalt and other lava rocks, cinders, tuff,
and other fragmental volcanic materials.
2. Sedimentary. Rocks that consist of chemical precipitates
and of rock fragments deposited by water, ice, or wind.
They include deposits of gravel, sand, silt, clay, and the
hardened equivalents of these — conglomerate, sandstone,
siltstone, shale, limestone, and deposits of gypsum and
salt.
3.Metamorphic. Rocks that are derived from both igneous and
sedimentary rocks through considerable alteration by heat
and pressure at great depths. They include gneiss, schist,
quartzite, slate, and marble.
The pores, joints, and crevices of the rocks in the zone of
saturation are generally filled with water. Although the openings in
these rocks are usually small, the total amount of water that can be
stored in the subsurface reservoirs of the rock formations is large.
The most productive aquifers are deposits of clean, coarse sand and
gravel; coarse, porous sandstones; cavernous limestones; and broken
lava rock. Some limestones, however, are very dense and
unproductive. Most of the igneous and metamorphic rocks are hard,
dense, and of low permeability. They generally yield small
quantities of water. Among the most unproductive formations are
the silts and clays. The openings in these materials are too small to
yield water, and the formations are structurally too incoherent to
maintain large openings under pressure. Compact materials near the
surface, with open joints similar to crevices in rock, may yield small
amounts of water.
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GROUND WATER BASINS
In an undeveloped ground water basin, movement of water to
lower basins, seepage from and to surface-water sources, and
transpiration are dependent upon the water in storage and the rate
of recharge. During periods following abundant rainfall, recharge
may exceed discharge. When recharge exceeds discharge, the excess
rainfall increases the amount of water available in storage in the
ground water basin. As the water table or artesian pressure rises, the
gradients to points of discharge become steeper and outflows
increase. When recharge ceases, storage decrease from outflow
causes water-table levels and artesian pressures to decline. In most
undeveloped basins the major fluctuations in storage are seasonal,
with the mean annual elevation of water levels showing little
variation. Thus, the average annual inflow to storage equals the
average annual outflow, a quantity of water referred to as the basin
yield.
The proper development of a ground water source requires
careful consideration of the hydrological and geological conditions
of the area. The individual who wishes to take full advantage of a
water source for domestic use should obtain the assistance of a
qualified ground water engineer, ground water geologist,
hydrologist, or contractor familiar with the construction of wells in
his area. He should rely on facts and experience, not on instinct or
intuition. Facts on the geology and hydrology of an area may be
available in publications of the U.S. Geological Survey or from
other Federal and State agencies. The National Water Well
Association1 also offers assistance.
SANITARY QUALITY OF GROUND WATER
When water seeps downward through overlying material to the
water table, particles in suspension, including micro-organisms, may
be removed. The extent of removal depends on the thickness and
character of the overlying material. Clay or "hardpan" provides the
most effective natural protection of ground water. Silt and sand
also provide good filtration if fine enough and in thick enough
layers. The bacterial quality of the water also improves during
storage in the aquifer because storage conditions are usually
unfavorable for bacterial survival. Clarity alone does not guarantee
that ground water is safe to drink; this can only be determined by
laboratory testing.
Ground water found in unconsolidated formations (sand, clay,
and gravel) and protected by similar materials from sources of
pollution is more likely to be safe than water coming from
consolidated formations (limestone, fractured rock, lava, etc.).
Where limited filtration is provided by overlying earth materials,
188 East Broad St., Columbus, Ohio 43215.
22
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water of better sanitary quality can sometimes be obtained by
drilling deeper. It should be recognized, however, that there are
areas where it is not possible, because of the geology, to find water
at greater depths. Much unnecessary drilling has been done in the
mistaken belief that more and better quality water can always be
obtained by drilling to deeper formations.
In areas without central sewerage systems, human excreta are
usually deposited in septic tanks, cesspools, or pit privies. Bacteria
in the liquid effluents from such installations may enter shallow
aquifers. Sewage effluents have been known to find their way
directly into water-bearing formations by way of abandoned wells
or soil-absorption systems. In such areas, the threat of
contamination may be reduced by proper well construction,
locating it farther from the source of contamination. The direction
of ground water flow usually approximates that of the surface flow.
It is always desirable to locate a well so that the normal movement
of ground water flow carries the contaminant away from the well.
CHEMICAL AND PHYSICAL QUALITY OF GROUND WATER
The mineral content of ground water reflects its movement
through the minerals which make up the earth's crust. Generally,
ground water in arid regions is harder and more mineralized than
water in regions of high annual rainfall. Also, deeper aquifers are
more likely to contain higher concentrations of minerals in solution
because the water has had more time (perhaps millions of years) to
dissolve the mineral rocks. For any ground water region there is a
depth below which salty water, or brine, is almost certain to be
found. This depth varies from one region to another.
Some substances found naturally in ground water, while not
necessarily harmful, may impart a disagreeable taste or undesirable
property to the water. Magnesium sulfate (Epsom salt), sodium
sulfate (Glauber's salt), and sodium chloride (common table salt)
are but a few of these. Iron and manganese are commonly found in
ground waters (see p. 9). It is an interesting fact that regular users
of waters containing amounts of these substances considered by
many to be excessive commonly become accustomed to the water
and consider it to have a good taste!
Concentrations of chlorides and nitrates that are usually high for
a particular region may be indicators of sewage pollution. This is
another reason why a chemical analysis of the water (p. 7) should
be made periodically and these results interpreted by someone
familiar with the area.
TEMPERATURE
The temperature of ground water remains nearly constant
throughout the year. Water from very shallow sources (less than 50
feet deep) may vary somewhat from one season to another, but
23
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water from deeper zones remains quite constant, its temperature
being close to that for the average annual temperature at the
surface. This is why water from a well may seem to be warm in
winter or cold during the summer.
Contrary to popular opinion, colder water is not obtained by
drilling deeper. Beyond about 100 feet of depth, the temperature of
ground water increases steadily at the rate of about 1°F for each 75
to 150 feet of depth. In volcanic regions this rate of increase may
be much greater.
DISTANCES TO SOURCES OF CONTAMINATION
All ground water sources should be located a safe distance from
sources of contamination. In cases where sources are severely
limited, however, a ground water aquifer that might become
contaminated may be considered for a water supply if treatment is
provided. After a decision has been made to locate a water source in
an area, it is necessary to determine the distance the source should
be placed from the origin of contamination and the direction of
water movement. A determination of a safe distance is based on
specific local factors described in the section on "Sanitary Survey"
in part I of this manual.
Because many factors affect the determination of "safe"
distances between ground water supplies and sources of pollution, it
is impractical to set fixed distances. Where insufficient information
is available to determine the "safe" distance, the distance should be
the maximum that economics, land ownership, geology, and
topography will permit. It should be noted that the direction of
ground water flow does not always follow the slope of the land
surface. Each installation should be inspected by a person with
sufficient training and experience to evaluate all of the factors
involved.
Since safety of a ground water source depends primarily on
considerations of good well construction and geology, these factors
should be the guides in determining safe distances for different
situations. The following criteria apply only to properly
constructed wells as described in this manual. There is no safe
distance for a poorly constructed well!
When a properly constructed well penetrates an unconsolidated
formation with good filtering properties, and when the aquifer itself
is separated from sources of contamination by similar materials,
research and experience have demonstrated that 50 feet is an
adequate distance separating the two. Lesser distances should be
accepted only after a comprehensive sanitary survey, conducted by
qualified State or local health agency officials, has satisfied the
officials that such lesser distances are both necessary and safe.
If it is proposed to install a properly constructed well in
formations of unknown character, the State or U.S. Geological
24
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Survey and the State or local health agency should be consulted.
When wells must be constructed in consolidated formations,
extra care should always be taken in the location of the well and in
setting "safe" distances, since pollutants have been known to travel
great distances in such formations. The owner should request
assistance from the State or local health agency.
The following table is offered as a guide in determining distances:
Formations
Minimum acceptable distance from
well to source of contamination
Favorable (unconsolidated).
50 feet. Lesser distances only on health department
approval following comprehensive sanitary survey of
proposed site and immediate surroundings.
Unknown
50 feet only after comprehensive geological survey of
the site and its surroundings has established, to the
satisfaction of the health agency, that favorable
formations do exist.
Poor (consolidated).
Safe distances can be established only following both
the comprehensive geological and comprehensive
sanitary surveys. These surveys also permit
determining the direction in which a well may be
located with respect to sources of contamination. In
no case should the acceptable distance be less than 50
feet.
EVALUATING CONTAMINATION THREATS TO WELLS
Conditions unfavorable to the control of contamination and that
may require specifying greater distances between a well and sources
of contamination are:
1. Nature of the contaminant. Human and animal excreta and
toxic chemical wastes are serious health hazards. Salts,
detergents, and other substances that dissolve in water
can mix with ground water and travel with it. They are
not ordinarily removed by natural filtration.
2. Deeper disposal. Cesspools, dry wells, disposal and waste
injection wells, and deep leaching pits that reach aquifers
or reduce the amount of filtering earth materials between
the wastes and the aquifer increase the danger of
contamination.
3. Limited filtration. When earth materials surrounding the
well and overlying the aquifer are too coarse to provide
effective filtration — as in limestone, coarse gravel, etc. —
or when they form a layer too thin, the risk of
contamination is increased.
4. The aquifer. When the materials of the aquifer itself are
too coarse to provide good filtration — as in limestone,
fractured rock, etc. — contaminants entering the aquifer
25
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through outcrops or excavations may travel great
distances. It is especially important in such cases to know
the direction of ground water flow and whether there are
outcrops of the formation (or excavations reaching it)
"upstream" and close enough to be a threat.
5. Volume of waste discharged. Since greater volumes of
wastes discharged and reaching an aquifer can
significantly change the slope of the water table and the
direction of ground water flow, it is obvious that heavier
discharges can increase the threat of contamination.
6. Contact surface. When pits and channels are designed and
constructed to increase the rate of absorption — as in
septic tank leaching systems, cesspools, and leaching pits
— more separation from the water source will be needed
than when tight sewer lines or waste pipes are used.
7. Concentration of contamination sources. The existence of
more than one source of contamination contributing to
the general area increases the total pollution load and,
consequently, the danger of contamination.
DEVELOPMENT OF GROUND WATER
The type of ground water development to be undertaken is
dependent upon the geological formations and hydrological
characteristics of the water-bearing formation. The development of
ground water falls into two main categories:
1. Development by wells
a. Nonartesian or water table
b. Artesian
2. Development from springs
a. Gravity
b. Artesian
Nonartesian wells are those that penetrate formations in which
ground water is found under water-table conditions. Pumping from
the well lowers the water table in the vicinity of the well and water
moves toward the well under the pressure differences thus
artificially created.
Artesian wells are those that penetrate aquifers in which the
ground water is found under hydrostatic pressure. Such a condition
occurs in an aquifer that is confined beneath an impermeable layer
of material at an elevation lower than that of the intake area of the
aquifer. The intake areas or recharge areas of confined aquifers are
commonly at high-level surface outcrops of the formations. Ground
water flow occurs from high-level outcrop areas to low-level
outcrop areas, which are areas of natural discharge. It also flows
toward points where water levels are lowered artificially by
pumping from wells. When the water level in the well stands above
26
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the top of the aquifer, the well is described as artesian. A well that
yields water by artesian pressure at the ground surface is a flowing
artesian well.
Gravity springs occur where water percolating laterally through
permeable material overlying an impermeable stratum comes to the
surface. They also occur where the land surface intersects the water
table. This type of spring is particularly sensitive to seasonal
fluctuations in ground water storage and frequently dwindles to a
seep or disappears during dry periods. Gravity springs are
characteristically low-discharge sources, but when properly
developed they make satisfactory individual water supply systems.
Artesian springs discharge from artesian aquifers. They may occur
where the confining formation over the artesian aquifer is ruptured
by a fault or where the aquifer discharges to a lower topographic
area. The flow from these springs depends on the difference in
recharge and discharge elevations of the aquifer and on the size of
the openings transmitting the water. Artesian springs are usually
more dependable than gravity springs, but they are particularly
sensitive to the pumping of wells developed in the same aquifer. As
a consequence, artesian springs may be dried by pumping.
Springs may be further classified by the nature of the passages
through which water issues from the source.
Seepage springs are those in which the water seeps out of sand,
gravel, or other material that contains many small interstices. The
term as used here includes many large springs as well as small ones.
Some of the large springs have extensive seepage areas and are
usually marked by the presence of abundant vegetation. The water
of small seepage springs may be colored or carry an oily scum
because of decomposition of organic matter or the presence of iron.
Seepage springs may emerge along the top of an impermeable bed,
but they occur more commonly where valleys are cut into the zone
of saturation of water-bearing deposits. These springs are generally
free from harmful bacteria, but they are susceptible to
contamination by surface runoff which collects in valleys or
depressions.
Tubular springs issue from relatively large channels, such as the
solution channels and caverns of limestone, and soluble rocks and
smaller channels that occur in glacial drift. They are sometimes
referred to as "bold" springs because the water issues freely from
one or more large openings. When the water reaches the channels by
percolation through sand or other fine-grained material, it is usually
free from contamination. When the channels receive surface water
directly or receive the indirect effluent of cesspools, privies, or
septic tanks, the water must be regarded as unsafe.
Fissure springs issue along bedding, joint, cleavage, or fault
planes. Their distinguishing feature is a break in the rocks along
27
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which the water passes. Some of these springs discharge
xmcontaminated water of deep-source origin. A large number of
thermal springs are of this type. Fissure springs, however, may
discharge water which is contaminated by surface drainage from
strata close to the surface.
DEVELOPMENT BY WELLS
When a well is pumped, the level of the water table in the vicinity
of the well will be lowered. (See fig. 2.) This lowering or
"drawdown" causes the water table or artesian pressure surface,
depending on the type of aquifer, to take the shape of an inverted
cone called a cone of depression. This cone, with the well at the
apex, is measured in terms of the difference between the static
water level and the pumping level. At increasing distances from the
well, the drawdown decreases until the slope of the cone merges
with the static water table. The distance from the well at which this
occurs is called the radius of influence. The radius of influence is
not constant but tends to continuously expand with continued
pumping. At a given pumping rate, the shape of the cone of
depression depends on the characteristics of the water-bearing
formation. Shallow and wide cones will form in highly permeable
aquifers composed of coarse sands or gravel. Steeper and narrower
cones will form in less permeable aquifers. As the pumping rate
increases, the drawdown increases and consequently the slope of
the cone steepens.
The character of the aquifer - artesian or water table — and the
physical characteristics of the formation which will affect the shape
of the cone include thickness, lateral extent, and the size and
grading of sands or gravels. In a material of low permeability such as
fine sand or sandy clay, the drawdown will be greater and the radius
of influence less than for the same pumpage from very coarse
gravel. (See fig. 2.)
For example, when other conditions are equal for two wells, it
may be expected that pumping costs for the same pumping rate will
be higher for the well surrounded by material of lower permeability
because of the greater drawdown.
When the cones of depression overlap, the local water table will
be lowered. (See fig. 2.) This requires additional pumping lifts to
obtain water from the interior portion of the group of wells. In
addition, a wider distribution of the wells over the ground water
basin will reduce the cost of pumping and will allow the
development of a larger quantity of water.
Yield of Wells
The amount of water that can be pumped from any well depends
on the character of the aquifer and the construction of the well.
Contrary to popular belief, doubling the diameter of a well
28
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EFFECT OF PUMPING ON CONE OF DEPRESSION
-Discharge
Ground Surface
e .Draw-Down ' Lesser Pumping Rite
• Discharge
EFFECT OF AQUI PER MATER IAL ON CONE OF DEPRES SI ON
_r- *- Discharge
Ground Surface
EFFECT OF OVERLAPPING FIELD OF INFLUENCE PUMPED WELLS
A --Discharge ?
Discharge
FIGURE 2. Pumping effects on aquifers.
29
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increases its yield only about 10 percent. Or, it could be said that it
decreases the drawdown only about 10 percent at the same
pumping rate. The casing diameter should be chosen to provide
enough room for proper installation of the pump. Individual wells
seldom require casings larger than 6 inches. Four-inch wells are
common in many areas.
A more effective way of increasing well capacity is by drilling
deeper into the aquifer — assuming, of course, that the aquifer has
the necessary thickness. The inlet portion of the well structure
(screen, perforations, slots) is also important in determining the
yield of a well in a sand or gravel formation. The amount of "open
area" in the screened or perforated portion exposed to the aquifer
is critical. Wells completed in consolidated formations are usually of
open hole construction; i.e., there is no casing in the aquifer itself.
It is not always possible to predict accurately the yield of a given
well before its completion. Knowledge can be gained, however,
from studying the geology of the area and interpreting the results
obtained from other wells constructed in the vicinity. This
information will be helpful in selecting the location and type of
well most likely to be successful. The information can also provide
an indication of the quantity or yield to expect.
A common way to describe the yield of a well is to express its
discharge capacity in relation to its drawdown. This relationship is
called the specific capacity of the well and is expressed in "gallons
per minute (gpm) per foot of drawdown." The specific capacity
may range from less than 1 gpm per foot of drawdown for a poorly
developed well or one in a tight aquifer to more than 100 gpm per
foot of drawdown for a properly developed well in a highly
permeable aquifer.
Table 3 gives general information on the practicality of
penetrating various types of geologic formations by the methods
indicated.
Dug wells can be sunk only a few feet below the water table. This
seriously limits the drawdown that can be imposed during pumping,
which in turn limits the yield of the well. A dug well that taps a
highly permeable formation such as gravel may yield 10 to 30 gpm
or even more in some situations with only 2 or 3 feet of drawdown.
If the formation is primarily fine sand, the yield may be on the
order of 2 to 10 gpm. These refer to dug wells of the sizes
commonly used.
Bored wells, like dug wells, can also be sunk only a limited depth
below the static water level. A penetration of 5 to 10 feet into the
water-bearing formation can probably be achieved. If the well is
nonartesian, the available drawdown would be 2 or 3 feet less than
the depth of water standing in the well. If the well taps an artesian
aquifer, however, the static water level will rise to some point above
30
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the top of the aquifer. This rise of the static water level increases
the depth of the water. The available drawdown and the yield of
the well will therefore be increased. A bored well tapping a highly
permeable aquifer and providing several feet of available drawdown
may yield 20 gpm or more. If the aquifer has a low permeability or
the depth of water in the well is small, the yield may be much
lower.
Driven wells can be sunk to as much as 30 feet or more below the
static water level. A well at this depth can provide 20 feet or more
of drawdown when being pumped. The small diameter of the well,
however, limits the type of pump that can be employed, so that the
yield under favorable conditions is limited to about 30 gpm. In fine
sand or sandy clay formations of limited thickness, the yield may
be less than 5 gpm.
Drilled and jetted wells can usually be sunk to such depths that
the depth of water standing in the well and consequently the
available drawdown will vary from less than 10 to hundreds of feet.
In productive formations of considerable thickness, yields of 300
gpm and more are readily attained. Drilled wells can be constructed
in all instances where driven wells are used and in many areas where
dug and bored wells are constructed. The larger diameter of a
drilled well as opposed to that of a driven well permits use of larger
pumping equipment that can develop the full capacity of the
aquifer. As has already been pointed out, the capacity or yield of a
well varies greatly, depending upon the permeability and thickness
of the formation, the construction of the well, and the available
drawdown.
Preparation of Ground Surface at Well Site
A properly constructed well should exclude surface water from a
ground water source to the same degree as does the undisturbed
overlying geologic formation. The top of the well must be
constructed so that no foreign matter or surface water can enter.
The well site should be properly drained and adequately protected
against erosion, flooding, and damage or contamination from
animals. Surface drainage should be diverted away from the well.
CONSTRUCTION OF WELLS
Dug Wells
The dug well, constructed by hand, is usually shallow. It is more
difficult to protect from contamination, although if finished
properly it may provide a satisfactory supply. Because of
advantages offered by other types of wells, consideration should
first be given to one of those described in this section.
Dug wells are usually excavated with pick and shovel. The
excavated material can be lifted to the surface by a bucket attached
32
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to a windlass or hoist. A power-operated clam shell or orange peel
bucket may be used in holes greater than 3 feet in diameter where
the material is principally gravel or sand. In dense clays or cemented
materials, pneumatic hand tools are effective means of excavation.
To prevent the native material from caving, one must place a crib
or lining in the excavation and move it downward as the pit is
deepened. The space between the lining and the undisturbed
embankment should be backfilled with clean material. In the region
of water-bearing formations, the backfilled material should be sand
or gravel. Cement grout should be placed to a depth of 10 feet
below the ground surface to prevent entrance of surface water along
the well lining. (See fig. 3.)
Dug wells may be lined with brick, stone, or concrete, depending
on the availability of materials and the cost of labor. Precast
concrete pipe, available in a wide range of sizes, provides an
excellent lining. This lining can be used as a crib as the pit is
deepened. When the lining is to be used as a crib, concrete pipe with
tongue-and-groove joints and smooth exterior surface is preferred.
(See fig. 3.)
Bell and spigot pipe may be used for a lining where it can be
placed inside the crib or in an unsupported pit. This type of pipe
requires careful backfilling to guarantee a tight well near the
surface. The prime factor with regard to preventing contaminated
water from entering a dug well is the sealing of the well lining and
otherwise excluding draining-in of surface water at and near the
well.
Most dug wells do not penetrate much below the water table
because of the difficulties in manual excavation and the positioning
of cribs and linings. The depth of excavation can be increased by
the use of pumps to lower the water level during construction.
Because of their shallow penetration into the zone of saturation,
many dug wells fail in times of drought when the water level
recedes or when large quantities of water are pumped from the
wells.
Bored Wells
Bored wells are commonly constructed with earth augers turned
either by hand or by power equipment. Such wells are usually
regarded as practical at depths of less than 100 feet when the water
requirement is low and the material overlying the water-bearing
formation has noncaving properties and contains few large boulders.
In suitable material, holes from 2 to 30 inches in diameter can be
bored to about 100 feet without caving.
In general, bored wells have the same characteristics as dug wells,
but they may be extended deeper into the water-bearing formation.
Bored wells may be cased with vitrified tile, concrete pipe,
33
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Note:
Pump screen to be
placed below point
of maximum draw-down
Pump Unit
Sanitary Well Seal
Cobble Drain
Reinforced Concrete
Cover Slab Sloped
Away From Pump
FIGURE 3. Dug well with two-pipe jet pump installation.
34
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Galvanized
Steel Alloy.or
Stainless Steel
Construction
Throughout
Continuous
Slot Type
Brass Jacket
Type
Brass Tube
Type
FIGURE 4. Different kinds of drive-well points.
standard wrought iron, steel casing, or other suitable material
capable of sustaining imposed loads. The well may be completed by
installing well screens or perforated casing in the water-bearing sand
and gravel. Proper protection from surface drainage should be
provided by sealing the casing with cement grout to the depth
necessary to protect the well from contamination. (See p. 48 and
app. A.)
Driven Wells
The simplest and least expensive of all well types is the driven
well. It is constructed by driving into the ground a drive-well point
which is fitted to the end of a series of pipe sections. (See figs. 4-5.)
The drive point is of forged or cast steel. Drive points are usually
1% or 2 inches in diameter. The well is driven with the aid of a
maul, or a special drive weight. (See fig. 5.) For deeper wells, the
well points are sometimes driven into water-bearing strata from the
bottom of a bored or dug well. (See fig. 6.) The yield of driven
35
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Single Pipe (shallow well)
Jet Pump
Sheet Plastic Separator
Cobble Drain
Reinforced Concrete
.Cover Slab Sloped
Away From Pump
FIGURE 6. Hand-bored well with driven well point and
"shallow well" jet pump.
37
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wells is generally small to moderate. Where they can be driven an
appreciable depth below the water table, they are no more likely
than bored wells to be seriously affected by water-table
fluctuations. The most suitable locations for driven wells are areas
containing alluvial deposits of high permeability. The presence of
coarse gravels, cobbles, or boulders interferes with sinking the well
point and may damage the wire mesh jacket.
Well-drive points can be obtained in a variety of designs and
materials. (See fig. 4.) In general, the serviceability and efficiency of
each is related to its basic design. The continuous-slot, wire-wound
type is more resistant to corrosion and can usually be treated with
chemicals to correct problems of incrustation. It is more efficient
because of its greater open area, and is easier to develop (see p. 44)
because its design permits easy access to the formation for cleanup.
Another type has a metal gauze wrapped around a perforated
steel pipe base and covered by a perforated jacket; if it contains
dissimilar metals, electrolytic corrosion is likely to shorten its life -
especially in corrosive waters.
Wherever maximum capacity is required, well-drive points of
good design are a worthwhile investment. The manufacturer should
be consulted for his recommendation of the metal alloy best suited
to the particular situation.
Good drive-well points are available with different size openings,
or slot sizes, for use in sands of different grain sizes. If too large a
slot size is used, it may never be possible to develop the well
properly, and the well is likely to be a "sand pumper," or gradually
to fill in with sand, cutting off the flow of water from the aquifer.
On the other hand, if the slot size chosen is too small, it may be
difficult to improve the well capacity by development, and the
yield may be too low. When the nature of aquifer sand is not
known beforehand, a medium-sized slot — 0.015 inch or 0.020 inch
— can be tried. If during development sand and sediments continue
indefinitely to pass through the slots, a smaller slot size should be
used. If, however, the water cleans up very quickly with very little
sand and sediment removed during development — less than
one-third of the volume of the drive point — then a larger slot size
could have been selected, resulting in more complete development
and greater well yield.
When a well is driven, it is desirable to prepare a pilot hole that
extends to the maximum practical depth. This can be done with a
hand auger slightly larger than the well point. After the pilot hole
has been prepared, the assembled point and pipe are lowered into
the hole. Depending on the resistance afforded by the formation,
driving is accomplished in several ways. The pipe is driven by
directly striking the drive cap, which is snugly threaded to the top
of the protruding section of the pipe. A maul, a sledge, or a special
38
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driver may be used to hand-drive the pipe. The special driver may
consist of a weight and sleeve arrangement which slides over the
drive cap as the weight is lifted and dropped in the driving process.
(See fig. 5.)
Jetted Wells
A rapid and efficient method of sinking well points is that of
jetting or washing-in. This method requires a source of water and a
pressure pump. Water forced under pressure down the riser pipe
issues from a special washing point. The well point and pipe are
then lowered as material is loosened by the jetting.
The riser pipe of a jetted well is often used as the suction pipe for
the pump. In such instances, surface water may be drawn into the
well if the pipe develops holes by corrosion. An outside protective
casing may be installed to the depth necessary to provide protection
against the possible entry of contaminated surface water. The
annular space between the casings should then be filled with cement
grout. The protective casing is best installed in an auger hole and
the drive point then driven inside it.
Drilled Wells
Construction of a drilled well (see fig. 7) is ordinarily
accomplished by one of two techniques - percussion or rotary
hydraulic drilling. The selection of the method depends primarily
on the geology of the site and the availability of equipment.
Percussion (Cable-Tool) Method. Drilling by the cable-tool or
percussion method is accomplished by raising and dropping a heavy
drill bit and stem. The impact of the bit crushes and dislodges
pieces of the formation. The reciprocating motion of the drill tools
mixes the drill cuttings with water into a slurry at the bottom of
the hole. This is periodically brought to the surface with a bailer, a
10- to 20-foot-long pipe equipped with a valve at the lower end.
Caving is prevented as drilling progresses by driving or sinking
into the ground a casing slightly larger in diameter than the bit.
When wells are drilled in hard rock, casing is usually necessary only
through the overburden of unconsolidated material. A casing may
be necessary in hard rock formations to prevent caving of beds of
softer material.
When good drilling practices are followed, water-bearing beds are
readily detected in cable-tool holes, because the slurry does not
tend to seal off the water-bearing formation. A rise or fall in the
water level in the hole during drilling, or more rapid recovery of the
water level during bailing, indicates that a permeable bed has been
entered. Crevices or soft streaks in hard formations are often water
bearing. Sand, gravel, limestone, and sandstone are generally
permeable and yield the most water.
Hydraulic Rotary Drilling Method. The hydraulic rotary drilling
39
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Plug Discharge
Ground Surface Sloped
to Drain Away from Well
Air Vent
FIGURE 7. Drilled well with submersible pump.
40
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method may be used in most formations. The essential parts of the
drilling assembly include a derrick and hoist, a revolving table
through which the drill pipe passes, a series of drill-pipe sections, a
cutting bit at the lower end of the drill pipe, a pump for circulation
of drilling fluid, and a power source to drive the drill.
In the drilling operation, the bit breaks up the material as it
rotates and advances. The drilling fluid (called mud) pumped down
the drill pipe picks up the drill cuttings and carries them up the
annular space between the rotating pipe and the wall of the hole.
The mixture of mud and cuttings is discharged to a settling pit
where the cuttings drop to the bottom and mud is recirculated to
the drill pipe.
When the hole is completed, the drill pipe is withdrawn and the
casing placed. The drilling mud is usually left in place and pumped
out after the casing and screen are positioned. The annular space
between the hole wall and the casing is generally filled with cement
grout in non-water-bearing sections, but may be enlarged and filled
with gravel at the level of water-bearing strata.
When little is known concerning the geology of the area, the
search for water-bearing formations must be done carefully and
deliberately so that all possible formations are located and tested.
Water-bearing formations may be difficult to recognize by the
rotary method or may be plugged by the pressure of the mud.
Air Rotary Drilling Method. The air rotary method i$ similar to
the rotary hydraulic method in that the same type of drilling
machine and tools may be used. The principal difference is that air
is the fluid used rather than mud or water. In place of the
conventional mud pump to circulate the fluids, air compressors are
used. Many drillers equip the rig with a mud pump to increase the
versatility of the equipment.
The air rotary method is well adapted to rapid penetration of
consolidated formations, and is especially popular in regions where
limestone is the principal source of water. It is not generally suited
to unconsolidated formations where careful sampling of rock
materials is required for well-screen installation. Small quantities of
water can be detected readily during drilling, and the yield
estimated. Larger sources of water may impede progress.
The air rotary method requires that air be supplied at pressures
from 100 to 250 pounds per square inch. To effect removal of the
cuttings, ascending velocities of at least 3,000 feet per minute are
necessary.
Penetration rates of 20 to 30 feet per hour in very hard rock are
common with air rotary methods.
Conventional mud drilling is sometimes used to drill through
caving formations that overlie bedrock. Casing may have to be
installed through the overburden before continuing with the air
41
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rotary method.
Down-the-Hole Air Hammer. The down-hole pneumatic hammer
combines the percussion effect of cable-tool drilling and the rotary
movement of rotary drilling. The tool bit is equipped with
tungsten-carbide inserts at the cutting surfaces. Tungsten-carbide is
very resistant to abrasion.
Water Well Casing and Pipe
There are several kinds of steel pipe that are suitable for casing
drilled wells. The following are the most commonly used:
Standard pipe
Line pipe
Drive pipe
Reamed and drifted (R&D) pipe
Water well casing
There are certain differences in sizes, in wall thicknesses, in types
of threaded connections available, and in methods of manufacture.
The important thing for the owner to know about well casing is
that it meet certain generally accepted specifications for quality of
the steel and thickness of the wall. Both are important because they
determine resistance to corrosion, and consequently the useful life
of the well. Strength of the casing may also be important in
determining whether certain well construction procedures may be
successfully carried out — particularly in cable-tool drilling where
hard driving of the casing is sometimes required.
The most commonly accepted specifications for water well casing
are those prepared by:
American Society for Testing and Materials (ASTM)
American Petroleum Institute (API)
American Iron and Steel Institute (AISI)
Federal Government
Each source lists several specifications that might be used, but those
most likely to be called for are ASTM A-120 and A-53, API 5-L,
AISI Standard for R&D pipe, and Federal specification WW-P-406B.
Table 4 lists "standard weight" wall thicknesses for standard pipe
and line pipe through the sizes ordinarily used in well construction.
Thinner pipe should not be used. If conditions in the area are
known to be highly corrosive, the "extra strong" and heavier
weights should be used.
Setting Screens or Slotted Casings in Wells
Screens or slotted casings are installed in wells to permit sand-free
water to flow into the well and to provide support for unstable
formations to prevent caving. The size of the slot for the screen or
perforated pipe should be based on a sieve analysis of carefully
selected samples of the water-bearing formation that is to be
developed. The analysis is usually made by the screen manufacturer.
42
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TABLE 4. — Steel pipe and casing, standard and standard line pipe
Nominal
size
(m.)
1'4
m
2
3
4
5
6
8
8
10
10
10
12
12
Diameters (in.)
Outside
1.660
1.900
2.375
3.500
4.500
5.563
6.625
8.625
8.625
10.750
10.750
10.750
12.750
12.750
Inside
1.380
1.610
2.067
3.068
4.026
5.047
6.065
8.071
7.981
10.192
10.136
10.020
12.090
12.000
Wall
thickness
(m.)
.140
.145
.154
.216
.237
.258
.280
.277
.322
.279
.307
.365
.330
.375
Approximate weight (Ib./ft.)
Plain ends
2.27
2.72
3.65
7.58
10.79
14.62
18.97
24.70
28.55
31.20
34.24
40.48
43.77
49.56
Threaded and
coupled
2.30
2.75
3.75
7.70
11.00
15.00
19.45
25.55
29.35
32.75
35.75
41.85
45.45
51.10
If the slot size is too large, the well may yield sand when pumped.
If the slots are too small, they may become plugged with fine
material and the well yield will be reduced. In a drilled well, the
screens are normally placed after the casing has been installed;
however, in a driven well, the screen is a part of the drive assembly
and is sunk to its final position as the well is driven.
The relationship between the open area of the screen and the
velocity of water through the openings should be considered if
maximum hydraulic efficiency is desired. Loss of energy through
friction is kept to a minimum by holding velocities to 0.1 foot per
second or less. Since the slot size is determined by the grain size
distribution in the aquifer sand, the required open area must be
obtained by varying the diameter — or, if aquifer thickness permits,
the length — of the screen. Manufacturers of well screens provide
tables of capacities and other information to facilitate selection of
the most economical screen dimensions.
Methods of screen installation in drilled wells include (1) the
pullback method, (2) the open-hole method, and (3) the baildown
method. The pullback method of installation is one in which the
casing is drawn back to expose a well screen placed inside the casing
at the bottom of the well. In the open-hole installation the screen
attached to the casing is inserted in the uncased bottom part of the
hole when the aquifer portion of the hole remains open. When the
baildown method is employed, the screen is placed at the bottom of
the cased hole and advanced into the water-bearing formation by
bailing the sand out from below the screen.
The pullback method is suited to bored or drilled wells, as long as
the casing can be moved, while the open-hole method is used in
most instances with rotary drilling. The baildown method may be
used in wells drilled by any method where water-bearing formations
43
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consist of sand. It is not well adapted to gravel formations.
A screen is seldom required in wells tapping bedrock or tightly
cemented sediments such as sandstone or limestone.
A fourth method, adaptable primarily in rotary drilled holes, is
the washdown method. This procedure entails the circulation of
water, by use of the mud pump, through a special self-closing
bottom upward around the screen and through the annular space
between the washpipe and the permanent casing to the surface. As
material is washed by jet action from below it, the well screen
settles to its desired position.
If the screen is placed after positioning of the casing, it must be
firmly sealed to the casing. This is generally done by swaging out a
lead packer attached to the top of the screen. When the pullback
method of installation is employed, a closed bail bottom usually
provides the bottom closure; a self-closing bottom serves this
purpose when the washdown method is used. A special plug is
placed in the bottom when the baildown method is employed. A
quantity of lead wool or a small bag of dry cement may also be
tamped into the bottom of the screen to seal it.
Development of Wells
Before a well is put into use, it is necessary to completely remove
silt and fine sand from the formation adjacent to the well screen by
one of several processes known as "development." The
development procedure unplugs the formation and produces a
natural filter of coarser and more uniform particles of high
permeability surrounding the well screen. After the development is
completed, there will be a well-graded, stabilized layer of coarse
material which will entirely surround the well screen and facilitate
the flow of water in the formation into the well.
The simplest method of well development is that of surging. In
this process the silt and sand grains are agitated by a series of rapid
reversals in the direction of flow of water and are drawn toward the
screen through larger pore openings. A well may be surged by
moving a plunger up and down in it. This action moves the water
alternately into and out of the formation. When water containing
fine granular material moves into the well, the particles tend to
settle to the bottom of the screen. They can be removed
subsequently by pumping or bailing.
One of the most effective methods of development is the
high-velocity hydraulic-jetting method. Water under pressure
ejected from orifices passes through the slot openings, violently
agitating the aquifer material. Sand grains finer than the slot size
move through the screen and either settle to the bottom of the well
(from which they are subsequently removed by bailing) or are
washed out at the top (if the, well overflows). Conventional
centrifugal or piston pumps may be used; or the mud pump of the
44
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rotary hydraulic drill easily accomplishes this. Pressures of at least
100 psi should be used, with pressure greater than 150 psi
preferred. In addition to the intensity of development that may be
applied by this method, it has the advantage of permitting selective
concentration of development on those portions of the screen most
in need. High-velocity jetting is of most benefit in screens of
continuous horizontal slot design. It has also proven effective in
washing out drilling mud and cuttings from crevices in hard-rock
wells. It is less useful in slotted or perforated pipe.
Other methods of development are interrupted pumping and,
sometimes in consolidated material, explosives when used only by
experts. The method of development must be suited to the aquifer
and the type of well construction. Proper development is necessary
in many formations and under many conditions for the completion
of a successful well. Its importance should not be overlooked.
Testing Well for Yield and Drawdown
In order that the most suitable pumping equipment can be
selected, a pumping test should be made after the well has been
developed to determine its yield and drawdown. The pumping test
for yield and drawdown should include the determination of the
volume of water pumped per minute or hour, the depth to the
pumping level as determined over a period of time at one or more
constant rates of pumpage, the recovery of the water level after
pumping is stopped, and the length of time the well is pumped at
each rate during the test procedure. When the completed well is
tested for yield and drawdown, it is essential that it be done
accurately by the use of approved measuring devices and accepted
methods. Additional information regarding the testing of wells for
drawdown or yield may be obtained from the U.S. Geological
Survey, the State or local health department, and the manufacturers
of well screens or pumping equipment.
Water table wells (see pp. 26, 28) are more affected than artesian
wells by seasonal fluctuations in ground water levels. When testing a
water table well for yield and drawdown, it is desirable - though
frequently not practical - to test it near the end of the dry season.
When this cannot be done, it is important to determine as nearly as
possible, from other wells tapping the same formations, the
additional seasonal decline in water levels that can be expected.
This additional decline should then be added to the drawdown
determined by the pumping test, in order to arrive at the ultimate
pumping water level. Seasonal declines of several feet in water table
wells are not unusual, and these can seriously reduce the capacity of
such wells in the dry season.
Individual wells should be test pumped at a constant pumping
rate that is not less than that planned for the final pump
45
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installation. The well should be pumped at this rate for not less
than 4 hours, and the maximum drawdown recorded. Measurements
of the water levels during recovery can then be made. Failure to
recover completely to the original static water level within 24 hours
should be reason to question the dependability of the water-bearing
formation.
Well Failure
Over a period of time, wells may fail to produce for any of these
main causes:
1. Failure or wear of the pump.
2. Declining water levels.
3. Plugged or corroded screens.
4. Accumulation of sand or sediments in the well.
Proper analysis of the cause necessitates measuring the water level
before, during, and after pumping. To facilitate measuring the water
level, one should provide for the entrance of a tape or an electrical
measuring device into the well in the annular space between the
well casing and the pump column (figs. 7-8).
An "air line" with a water-depth indicating gage, available from
pump suppliers, may also be used. On some larger wells, the air line
Drive Water"
iea ^^^^H ^^^H*""
•" ^^^^| ^^H
Pipe
FIGURE 8. Well seal for jet pump installation.
46
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and gage are left installed so that periodic readings can be taken and
a record of well and pump performance kept. While not as accurate
as the tape or electrode method, this installation is popular for use
in a well that is being pumped because it is unaffected by water that
may be falling from above.
Unless the well is the pitless adapter or pitless unit type (p. 109),
access for water-level measurements can be obtained through a
threaded hole in the sanitary well seal (figs. 8-9). This is true for
submersible and jet pump installations, as well as for some others. If
it is not possible to gain access through the top of the well, access
may be provided by means of a pipe welded to the side of the
casing. (See discussion under "Installation of Pumping Equipment,"
p. 104.)
If the well is completed as a pitless adapter installation (p. 109),
Pipe Plug
Drop Pipe from
Submersible
Pump
Submersible
Pump Cable
FIGURE 9. Well seal for submersible pump installation.
47
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it is usually possible to slide the measuring device past the adapter
assembly inside the casing and on to the water below. If it is a
pitless unit, particularly the "spool" type (see fig. 22, p. 112), it
probably will not be possible to reach the water level. In the latter
case, the well can only be tested by removing the spool and pump
and reinstalling the pump, or another one, without the spool.
Any work performed within the well — including insertion of a
measuring line — is likely to contaminate the water with coliform
bacteria and other organisms. The well should be disinfected (see p.
50) before returning it to service. All access holes should be tightly
plugged or covered following the work.
Sanitary Construction of Wells
The penetration of a water-bearing formation by a well provides a
direct route for possible contamination of the ground water.
Although there are different types of wells and well construction,
there are basic sanitary aspects that must be considered and
followed.
1. The annular space outside the casing should be filled with a
watertight cement grout or puddled clay from a point
just below the frost line or deepest level of excavation
near the well (see "Pitless Units and Adapters," p.109), to
as deep as necessary to prevent entry of contaminated
water. See appendix A for grouting recommendations.
2. For artesian aquifers, the casing should be sealed into the
overlying impermeable formations so as to retain the
artesian pressure.
3. When a water-bearing formation containing water of poor
quality is penetrated, the formation should be sealed off
to prevent the infiltration of water into the well and
aquifer.
4. A sanitary well seal with an approved vent should be
installed at the top of the well casing to prevent the
entrance of contaminated water or other objectionable
material.
For large-diameter wells such as dug wells, it would be difficult to
provide a sanitary well seal; consequently, a reinforced concrete
slab, overlapping the casing and sealed to it with a flexible sealant
or rubber gasket, should be installed. The annular space outside the
casing should first be filled with suitable grouting or sealing
materials — cement, clay, or fine sand.
Well Covers and Seals
Every well should be provided with an overlapping, tight-fitting
cover at the top of the casing or pipe sleeve to prevent
contaminated water or other material from entering the well.
The sanitary well seal in a well exposed to possible flooding
48
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should be either watertight or elevated at least 2 feet above the
highest known flood level. When it is expected that a well seal may
become flooded, it should be watertight and equipped with a vent
line whose opening to the atmosphere is at least 2 feet above the
highest known flood level.
The seal in a well not exposed to possible flooding should be
either watertight (with an approved vent line) or self-draining with
an overlapping and downward flange. If the seal is of the
self-draining (nonwatertight) type, all openings in the cover should
be either watertight or flanged upward and provided with
overlapping, downward flanged covers.
Some pump and power units have closed bases that effectively
seal the upper terminal of the well casing. When the unit is the open
type, or when it is located at the side (some jet- and
suction-pump-type installations), it is especially important that a
sanitary well seal be used. There are several acceptable designs
consisting of an expandable neoprene gasket compressed between
two steel plates (see figs. 8-9). They are easily installed and removed
for well servicing. Pump and water well suppliers normally stock
sanitary well seals.
If the pump is not installed immediately after well drilling and
placement of the casing, the top of the casing should be closed with
a metal cap screwed or tack-welded into place, or covered with a
sanitary well seal.
A well slab alone is not an effective sanitary defense, since it can
be undermined by burrowing animals and insects, cracked from
settlement or frost heave, or broken by vehicles and vibrating
machinery. The cement grout formation seal is far more effective.
(See p. 48.) It is recognized, however, that there are situations that
call for a concrete slab or floor around the well casing to facilitate
cleaning and improve appearance. When such a floor is necessary, it
should be placed only after the formation seal and the pitless
installation (see p. 109) have been inspected.
Well covers and pump platforms should be elevated above the
adjacent finished ground level. Pumproom floors should be
constructed of reinforced, watertight concrete, and carefully leveled
or sloped away from the well so that surface and waste water
cannot stand near the well. The minimum thickness of such a slab
or floor should be 4 inches. Concrete slabs or floors should be
poured separately from the cement formation seal and — when the
threat of freezing exists — insulated from it and the well casing by a
plastic or mastic coating or sleeve to prevent bonding of the
concrete to either.
All water wells should be readily accessible at the top for
inspection, servicing, and testing. This requires that any structure
over the well be easily removable to provide full, unobstructed
49
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access for well-servicing equipment. The so-called "buried seal,"
with the well cover buried under several feet of earth, is
unacceptable because (1) it discourages periodic inspection and
preventive maintenance, (2) it makes severe contamination during
pump servicing and well repair more likely, (3) any well servicing is
more expensive, and (4) excavation to expose the top of the well
increases the risk of damage to the well, the cover, the vent and the
electrical connections.
Disinfection of Wells
All newly constructed wells should be disinfected to neutralize
contamination from equipment, material, or surface drainage
introduced during construction. Every well should be disinfected
promptly after construction or repair.
An effective and economical method of disinfecting wells and
appurtenances is that of using calcium hypochlorite containing
approximately 70-percent available chlorine. This chemical can be
purchased in granular or tablet form at hardware stores, swimming
pool equipment supply outlets, or chemical supply houses.
When used in the disinfection of wells, calcium hypochlorite
should be added in sufficient amounts to provide a dosage of
approximately 100 mg/K of available chlorine in the well water.
This concentration is roughly equivalent to a mixture of 2 ounces
of dry chemical per 100 gallons of water to be disinfected. Practical
disinfection requires the use of a stock solution. The stock solution
may be prepared by mixing 2 ounces of high-test hypochlorite with
2 quarts of water. Mixing is facilitated if a small amount of the
water is first added to the granular calcium hypochlorite and stirred
to a smooth watery paste free of lumps. It should then be mixed
with the remaining quantity of water. The stock solution should be
stirred thoroughly for 10 to 15 minutes prior to allowing the inert
ingredients to settle. The clearer liquid containing the chlorine
should be used and the inert material discarded. Each 2 quarts of
stock solution will provide a concentration of approximately 100
mg/£ when added to 100 gallons of water. The solution should be
prepared in a thoroughly clean utensil; the use of metal containers
should be avoided, if possible, as they are corroded by strong
chlorine solutions. Crockery, glass, or rubber-lined containers are
recommended.
Where small quantities of disinfectant are required and a scale is
not available, the material can be measured with a spoon. A heaping
tablespoonful of granular calcium hypochlorite weighs
approximately Vz ounce.
When calcium hypochlorite is not available, other sources of
available chlorine, such as sodium hypochlorite (12-15 percent of
volume), can be used. Sodium hypochlorite, which is also
50
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commonly available as liquid household bleach with 5.25 percent
available chlorine, can be diluted with one part of water to produce
the stock solution. Two quarts of this solution can be used for
disinfecting 100 gallons of water.
Stock solutions of chlorine in any form will deteriorate rapidly
unless properly stored. Dark glass or plastic bottles with airtight
caps are recommended. Bottles containing solution should be kept
in a cool place and protected from direct sunlight. If proper storage
facilities are not available, the solution should always be prepared
fresh immediately before use. Commercially available household
bleach solutions, because of their convenience and usual reliability
as to concentration or strength, are preferred stock solutions for
disinfecting individual water supplies.
Table 5 shows quantities of disinfectants to be used in treating
wells of different diameters and water depths. For sizes or depths
not shown, the next larger figure should be used.
Dug Wells
1. After the casing or lining has been completed, follow the
procedure outlined below before placing the cover platform over
the well.
a. Remove all equipment and materials, including tools, forms,
platforms, etc., that will not form a permanent part of
the completed structure.
b. Using a stiff broom or brush, wash the interior wall of the
casing or lining with a strong solution (100 mg/C of
chlorine) to insure thorough cleaning.
2. Place the cover over the well and pour the required amount of
chlorine solution into the well through the manhole or pipesleeve
opening just before inserting the pump cylinder and drop-pipe
assembly. The chlorine solution should be distributed over as much
of the surface of the water as possible to obtain proper diffusion of
the chemical through the water. Diffusion of the chemical with the
well water may be facilitated by running the solution into the well
through the water hose or pipeline as the line is being alternately
raised and lowered. This method should be followed whenever
possible.
3. Wash the exterior surface of the pump cylinder and drop pipe
with the chlorine solution as the assembly is being lowered into the
well.
4. After the pump has been set in position, pump water from the
well until a strong odor of chlorine is noted.
5. Allow the chlorine solution to remain in the well for not less
than 24 hours.
6. After 24 hours or more have elapsed, flush the well to remove
all traces of chlorine.
51
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Drilled, Driven, and Bored Wells
1. When the well is being tested for yield, the testpump should
be operated until the well water is as clear and as free from
turbidity as possible.
2. After the testing equipment has been removed, slowly pour
the required amount of chlorine solution into the well just before
installing the permanent pumping equipment. Diffusion of the
solution with the well water may be facilitated as previously
described in item 2, "Dug Wells."
3. Add 5 or 10 gallons of clean, chlorinated water (see Table 5)
to the well to force the solution out into the formation. One-half
teaspoon of calcium hypochlorite or one-half cup of laundry bleach
in 5 gallons of water is enough for this purpose.
4. Wash the exterior surface of the pump cylinder and drop pipe
as they are lowered into the well.
5. After the pump has been set in position, operate the pump
until a distinct odor of chlorine can be detected in the water
discharged.
6. Allow the chlorine solution to remain in the well for at least 4
hours - preferably overnight.
7. After disinfection, pump the well until the odor of chlorine
can no longer be noticed in the water discharged.
In the case of deep wells having a high water level, it may be
necessary to resort to special methods of introducing the
disinfecting agent into the well so as to insure proper diffusion of
chlorine throughout the well. The following method is suggested.
Place the granulated calcium hypochlorite in a short section of
pipe capped at both ends. A number of small holes should be drilled
through each cap or into the sides of the pipe. One of the caps
should be fitted with an eye to facilitate attachment of a suitable
cable. The disinfecting agent is distributed when the pipe section is
lowered or raised throughout the depth of the water.
Flowing Artesian Wells
The water from flowing artesian wells is generally free from
contamination as soon as the well is completed or after it has been
allowed to flow a short time. It is therefore not generally necessary
to disinfect flowing wells. If, however, analyses show persistent
contamination, the well should be thoroughly disinfected as
follows.
Use a device such as the pipe described in the preceding section
or any other appropriate device by means of which a surplus supply
of disinfectant can be placed at or near the bottom of the well. The
cable supporting the device can be passed through a stuffing box at
the top of the well. After the disinfectant has been placed at or near
the bottom of the well, throttle down the flow sufficiently to
53
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obtain an adequate concentration. When water showing an adequate
disinfectant concentration appears at the surface, close the valve
completely and keep it closed for at least 24 hours.
Bacteriological Tests Following Disinfection
If the bacteriological examination of water samples collected
after disinfection indicates that the water is not safe for use,
disinfection should be repeated until tests show that water samples
from that portion of the system being disinfected are satisfactory.
Samples collected immediately after disinfection may not be
representative of the water served normally. Hence, if
bacteriological samples are collected immediately after disinfection,
it is necessary that the sampling be repeated several days later to
check on the delivered water under normal conditions of operation
and use. The water from the system should not be used for
domestic and culinary purposes until the reports of the tests
indicate that the water is safe for such uses. If after repeated
disinfection the water is unsatisfactory, treatment of the supply is
needed to provide water which always meets the Public Health
Service Drinking Water Standards. Under these conditions, the
supply should not be used for drinking and culinary purposes until
adequate treatment has been provided.
Abandonment of Wells
Unsealed, abandoned wells constitute a potential hazard to the
public health and welfare of the surrounding area. The sealing of an
abandoned well presents certain problems, the solution of which
involves consideration of the construction of the well and the
geological and hydrological conditions of the area. In the proper
sealing of a well, the main factors to be considered are elimination
of any physical hazard, the prevention of any possible
contamination of the ground water, the conservation and
maintenance of the yield and hydrostatic pressure of the aquifer,
and the prevention of any possible contact between desirable and
undesirable waters.
The basic concept behind the proper sealing of any abandoned
well is that of restoration, as far as feasible, of the controlling
geological conditions that existed before the well was drilled or
constructed. If this restoration can be properly accomplished, an
abandoned well will not create a physical or health hazard.
When a well is to be permanently abandoned, the lower portion
of it is best protected when filled with concrete, cement grout, neat
cement, or clays with sealing properties similar to those of cement.
When dug or bored wells are filled, as much of the lining should be
removed as possible so that surface water will not reach the
water-bearing strata through a porous lining or one containing
cracks or fissures. When any question arises, follow the regulations
54
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and recommendations of the State or local health department.
Abandoned wells should never be used for the disposal of sewage
or other wastes.
Reconstruction of Existing Dug Wells
Existing wells used for domestic water supplies subject to
contamination should be reconstructed so as to insure safe water.
When reconstruction is not practicable, the water supply should be
treated or a new well constructed.
Dug wells with stone or brick casings can often be rebuilt by
enclosing existing casings with concrete or by the use of a buried
concrete slab.
Care must be exercised on entering wells because until properly
ventilated they may contain dangerous gases or lack oxygen.
Hydrogen sulfide gas is found in certain ground waters and, being
heavier than air, tends to accumulate in excavations. It is explosive,
and nearly as poisonous as cyanide. Also, a person's sense of smell
tires quickly in its presence, so that he is unable to sense danger.
Concentrations may become dangerous without further warning.
Methane gas is also found in some ground water or in
underground formations. It is the product of the decomposition of
organic matter. It is not toxic, but is highly explosive.
Gasoline or carbide lanterns or candles may not be reliable
indicators of safe atmospheres within a well, as many of these
devices will continue to burn at oxygen levels well below those safe
for humans. Also, any open flame carries the additional risk of an
explosion from accumulated combustible gases.
The "flame safety lamp" used by miners, construction
companies, and utilities service departments is a much better device
for determining safe atmospheres. It is readily obtainable from mine
safety equipment suppliers. It should be lowered on a rope to the
bottom of the well to test the atmosphere. Even after the well has
passed this test, the first person to enter the well should carry a
safety rope tied around his waist, with two persons standing by,
above ground, to rescue him at the first sign of dizziness or other
distress.
Improvements should be planned so that the reconstructed well
will conform as nearly as possible with the principles set forth in
this manual. If there is any doubt as to what should be done, advice
should be obtained from the State or local health department.
Special Considerations in Constructing Artesian Wells
In order that the water may be conserved and the productivity of
an artesian well improved, it is essential that the casing be sealed
into the confining stratum. Otherwise, a loss of water may occur by
leakage into lower pressure permeable strata at higher elevations. A
flowing artesian well should be designed so that the movement of
55
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water from the aquifer can be controlled. Water can be conserved if
such a well is equipped with a valve or shutoff device. When the
recharge area and aquifer are large and the number of wells which
penetrate the aquifer are small, the flowing artesian well produces a
fairly steady flow of water throughout the year.
DEVELOPMENT OF SPRINGS
There are two general requirements necessary in the development
of a spring used as a source of domestic water: (1) selection of a
spring with adequate capacity to provide the required quantity or
quality of water for its intended use throughout the year, (2)
protection of the sanitary quality of the spring. The measures taken
to develop a spring must be tailored to its geological conditions and
sources.
The features of a spring encasement are the following: (1) an
open-bottom, watertight basin intercepting the source which
extends to bedrock or a system of collection pipes and a storage
tank, (2) a cover that prevents the entrance of surface drainage or
debris into the storage tank, (3) provision for the cleanout and
emptying of the tank contents, (4) provision for overflow, and (5) a
connection to the distribution system or auxiliary supply. (See fig.
10.)
A tank is usually constructed in place with reinforced concrete of
such dimensions as to enclose or intercept as much of the spring as
possible. When a spring is located on a hillside, the downhill wall
and sides are extended to bedrock or to a depth that will insure
maintenance of an adequate water level in the tank. Supplementary
cutoff walls of concrete or impermeable clay extending laterally
from the tank may be used to assist in controlling the water table in
the locality of the tank. The lower portion of the uphill wall of the
tank can be constructed of stone, brick, or other material so placed
that water may move freely into the tank from the formation.
Backfill of graded gravel and sand will aid in restricting movement
of fine material from the formation toward the tank.
The tank cover should be cast in place to insure a good fit. Forms
should be designed to allow for shrinkage of concrete and expansion
of form lumber. The cover should extend down over the top edge
of the tank at least 2 inches. The tank cover should be heavy
enough so that it cannot be dislodged by children and should be
equipped for locking.
A drain pipe with an exterior valve should be placed close to the
wall of the tank near the bottom. The pipe should extend
horizontally so as to clear the normal ground level at the point of
discharge by at least 6 inches. The discharge end of the pipe should
be screened to prevent the entrance of rodents and insects.
The overflow is usually placed slightly below the maximum
water-level elevation and screened. A drain apron of rock should be
56
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-Ctewiout Brain
Perforated Pipe—-j
|Surface Waters,
Diversion
Ditch J
Fence-J
PUN
Surface Water
Diversion Ditch-
Lock
-.'•'. •-:/.• Wpe /.'••'.;-
Waler'-Bsarlng Gravel;
' . . EUVATION
FIGURE 10. Spring protection.
57
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provided to prevent soil erosion at the point of overflow discharge.
The supply outlet from the developed spring should be located
about 6 inches above the drain outlet and properly screened. Care
should be taken in casting pipes into the walls of the tank to insure
good bond with the concrete and freedom from honeycomb around
the pipes.
Sanitary Protection of Springs
Springs usually become contaminated when barnyards, sewers,
septic tanks, cesspools, or other sources of pollution are located on
higher adjacent land. In limestone formations, however,
contaminated material frequently enters the water-bearing channels
through sink holes or other large openings and may be carried along
with ground water for long distances. Similarly, if material from
such sources of contamination finds access to the tubular channels
in glacial drift, this water may retain its contamination for long
periods of time and for long distances.
The following precautionary measures will help to insure
developed spring water of a consistently high quality:
1. Provide for the removal of surface drainage from the site. A
surface drainage ditch should be located uphill from the
source so as to intercept surface-water runoff and carry it
away from the source. Location of the ditch and the
points at which the water should be discharged are a
matter of judgment. Criteria used should include the
topography, the subsurface geology, land ownership, and
land use.
2. Construct a fence to prevent entry of livestock. Its location
should be guided by the considerations mentioned in item
1. The fence should exclude livestock from the
surface-water drainage system at all points uphill from the
source.
3. Provide for access to the tank for maintenance, but prevent
removal of the cover by a suitable locking device.
4. Monitor the quality of the spring water with periodic checks
for contamination. A marked increase in turbidity or flow
after a rainstorm is a good indication that surface runoff is
reaching the spring.
Disinfection of Springs
Spring encasements should be disinfected by a procedure similar
to that used for dug wells. If the water pressure is not sufficient to
raise the water to the top of the encasement, it may be possible to
shut off the flow and thus keep the disinfectant in the encasement
for 24 hours. If the flow cannot be shut off entirely, arrangements
should be made to supply disinfectant continuously for as long a
period as practicable.
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INFILTRATION GALLERIES
Many recreational or other developments located in the
mountains have access to water supplies that are located near the
headwaters of mountain streams where the watersheds are generally
heavily forested and uninhabited by man. Even under these
conditions, pathogenic bacteria — in addition to soil bacteria — have
been found in the water.
Some of the major problems which are encountered in operating
and maintaining these supplies are created by debris and turbidity
encountered at the waterworks intake following spring thaws and
periods of heavy rainfall. When practical, arrangements should be
made to remove this material before it reaches the intake.
Experience has demonstrated that this material can be removed
successfully, especially when small volumes of water are involved,
by installing an infiltration gallery at or near the intake.
Where soil formations adjoining a stream are favorable, the water
can be intercepted by an infiltration gallery located a reasonable
distance from the high-water level and a safe distance below the
ground surface. The gallery should be installed so that it will
intercept the flow from the stream after flowing through the
intervening soil formations between the stream and infiltration
gallery.
A typical installation generally involves the construction of an
underdrained, sand-filter trench located parallel to the stream bed
and about 10 feet from the high-water mark. The sand filter is
usually located in a trench with a minimum width of 30 inches and
a depth of about 10 feet. At the bottom of the trench, perforated
or open joint tile is laid in a bed of gravel about 12 inches in
thickness with about 4 inches of graded gravel located over the top
of the tile to support the filtering material. The embedded tile is
then covered with clean, coarse sand to a minimum depth of 24
inches, and the remainder of the trench backfilled with fairly
impervious material. The collection tile is terminated in a
watertight, concrete basin from where it is diverted or pumped to
the distribution system following chlorination.
Where soil formations adjoining a stream are unfavorable for the
location of an infiltration gallery, the debris and turbidity which are
occasionally encountered in a mountain stream can be removed by
constructing a modified infiltration gallery-slow sand filter
combination in the stream bed. A typical installation involves the
construction of a dam across the stream to form a natural pool or
the excavation of a pool behind the dam. The filter is installed in
the pool behind the dam by laying perforated pipe in a bed of
graded gravel which is covered by at least 24 inches of clean, coarse
sand. About 24 inches of free board should be allowed between the
surface of the sand and the dam spillway. The collection lines
59
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usually terminate in a watertight, concrete basin located adjacent to
the upstream face of the dam from where the water is diverted to
chlorination facilities. Experience with these units indicates that
they provide satisfactory service with limited maintenance.
60
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Part III
Surface Water
for Rural Use
The selection and use of surface-water sources for individual
water supply systems require consideration of additional factors not
usually associated with ground water sources. When small streams,
open ponds, lakes, or open reservoirs must be used as sources of
water supply, the danger of contamination and of the consequent
spread of enteric diseases such as typhoid fever and dysentery is
increased. As a rule, surface water should be used only when ground
water sources are not available or are inadequate. Clear water is not
always safe, and the old saying that running water "purifies itself
to drinking water quality within a stated distance is false.
The physical and bacteriological contamination of surface water
makes it necessary to regard such sources of supply as unsafe for
domestic use unless reliable treatment, including filtration and
disinfection, is provided.
The treatment of surface water to insure a constant, safe supply
requires diligent attention to operation and maintenance by the
owner of the system.
When ground water sources are limited, consideration should be
given to their development for domestic purposes only.
Surface-water sources can then provide water needed for stock and
poultry watering, gardening, firefighting, and similar purposes.
Treatment of surface water used for livestock is not generally
considered essential. There is, however, a trend to provide stock and
poultry drinking water which is free from bacterial contamination
and certain chemical elements.
SOURCES OF SURFACE WATER
Principal sources of surface water which may be developed
include controlled catchments, ponds or lakes, surface streams, and
irrigation canals. Except for irrigation canals, where discharges are
dependent on irrigation activity, these sources derive water from
direct precipitation over the drainage area.
Because of the complexities of the hydrological, geological, and
meteorological factors affecting surface-water sources, it is
recommended that in planning the development of natural
catchment areas of more than a few acres, engineering advice be
obtained.
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To estimate the yield of the source, it is necessary for one to
consider the following information pertaining to the drainage area.
1. Total annual precipitation.
2. Seasonal distribution of precipitation.
3. Annual or monthly variations of rainfall from normal levels.
4. Annual and monthly evaporation and transpiration rates.
5. Soil moisture requirements and infiltration rates.
6. Runoff gage information.
7. All available local experience records.
Much of the required data, particularly that concerning
precipitation, can be obtained from publications of the U.S.
Weather Bureau. Essential data such as soil moisture and
evapotranspiration requirements may be obtained from local soil
conservation and agricultural agencies or from field tests conducted
by hydrologists.
Controlled Catchments
In some areas ground water is so inaccessible or so highly
mineralized that it is not satisfactory for domestic use. In these
cases the use of controlled catchments and cisterns may be
necessary. A properly located and constructed controlled
catchment and cistern, augmented by a satisfactory filtration unit
and adequate disinfection facilities, will provide a safe water.
A controlled catchment is a defined surface area from which
rainfall runoff is collected. It may be a roof or a paved ground
surface. The collected water is stored in a constructed covered tank
called a cistern or reservoir. Ground-surface catchments should be
fenced to prevent unauthorized entrance by either man or animals.
There should be no possibility of the mixture of undesirable surface
drainage and controlled runoff. An intercepting drainage ditch
around the upper edge of the area and a raised curb around the
surface will prevent the entry of any undesirable surface drainage.
For these controlled catchments, simple guidelines to determine
water yield from rainfall totals can be established. When the
controlled catchment area has a smooth surface or is paved and the
runoff is collected in a cistern, water loss due to evaporation,
replacement of soil moisture deficit, and infiltration is small. As a
general rule, losses from smooth concrete or asphalt-covered ground
catchments average less than 10 percent; for shingled roofs or tar
and gravel surfaces losses should not exceed 15 percent, and for
sheet metal roofs the loss is negligible.
A conservative design can be based on the assumption that the
amount of water that can be recovered for use is three-fourths of
the total annual rainfall. (See fig. 11.)
Location. A controlled catchment may be suitably located on a
hillside near the edge of a natural bench. The catchment area can be
placed on a moderate slope above the receiving cistern.
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150
130
no
90
70
50
30
10
Runoff-0.75 Total Preciptation
~Z
2,000 4,000
Horizontal Area of Catchment, (In Square Feet)
6,000
FIGURE 11. Yield of impervious catchment area.
The location of the cistern should be governed by both
convenience and quality protection. A cistern should be as close to
the point of ultimate use as practical. A cistern should not be
placed closer than 50 feet from any part of a sewage-disposal
installation, and should be on higher ground.
Cisterns collecting water from roof surfaces should be located
adjacent to the building, but not in basements subject to flooding.
They may be placed below the surface of the ground for protection
against freezing in cold climates and to keep water temperatures
low in warm climates but should be situated on the highest ground
practicable, with the surrounding area graded to provide good
drainage.
Size. The size of a cistern needed will depend on the size of the
family and the length of time between periods of heavy rainfall.
Daily water requirements can be estimated from Table 1, p. 15. The
size of the catchment or roof will depend on the amount of rainfall
and the character of the surface. It is desirable to allow a safety
factor for lower than normal rainfall levels. Designing for two-thirds
of the mean annual rainfall will result usually in a catchment area of
adequate capacity.
The following example illustrates the procedure for determining
63
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the size of the cistern and required catchment area. Assume that the
minimum drinking and culinary requirements of a family of four
persons are 100 gallons per day1 (4 persons X 25 gallons per day =
100 gallons) and that the effective period2 between rainy periods is
150 days. The minimum volume of the cistern required will be
15,000 gallons (100X150). This volume could be held by a cistern
10 feet deep and 15 feet square. If the mean annual rainfall is 50
inches, then the total design rainfall is 33 inches (50X2/3). In figure
11 the catchment area required to produce 36,500 gallons (365
days X 100 gallons per day) - the total year's requirement - is
2,400 square feet.
Construction. Cisterns should be of watertight construction
with smooth interior surfaces. Manhole or other covers should be
tight to prevent the entrance of light, dust, surface water, insects,
and animals.
Manhole openings should have a watertight curb with edges
projecting a minimum of 4 inches above the level of the
surrounding surface. The edges of the manhole cover should overlap
the curb and project downward a minimum of 2 inches. The covers
should be provided with locks to minimize the danger of
contamination and accidents.
Provision can be made for diverting initial runoff from paved
surfaces or roof tops before the runoff is allowed to enter the
cistern. (See fig. 12.)
Inlet, outlet, and waste pipes should be effectively screened.
Cistern drains and waste or sewer lines should not be connected.
Underground cisterns can be built of brick or stone, although
reinforced concrete is preferable. If used, brick or stone must be
low in permeability and laid with full portland cement mortar joints.
Brick should be wet before laying. High-quality workmanship is
required, and the use of unskilled labor for laying brick or stone is
not advisable. Two 1/2-inch plaster coats of 1:3 portland cement
mortar on the interior surface will aid in providing waterproofing. A
hard impervious surface can be made by troweling the final coat
before it is fully hardened.
Figure 12 shows a suggested design for a cistern of reinforced
concrete. A dense concrete should be used to obtain watertightness
and should be vibrated adequately during construction to eliminate
honeycomb. All masonry cisterns should be allowed to wet cure
properly before being used.
The procedures outlined in part V of this manual should be
followed in disinfecting the cistern with chlorine solutions. Initial
twenty-five gallons per person per day, assuming that other uses are supplied by water
of poorer quality.
2F,ffcetive period is the number of days between periods of rainfall during which there is
negligible precipitation.
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e
l-l
01
O
a
o
65
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and periodic water samples should be taken to determine the
bacteriological quality of the water supply. Chlorination may be
required on a continuing basis if the bacteriological results indicate
that the quality is unsatisfactory.
Ponds or Lakes
A pond or lake should be considered as a source of water supply
only after ground water sources and controlled catchment systems
are found to be inadequate or unacceptable. The development of a
pond as a supply source depends on several factors: (1) the
selection of a watershed that permits only water of the highest
quality to enter the pond, (2) usage of the best water collected in
the pond, (3) filtration of the water to remove turbidity and reduce
bacteria, (4) disinfection of filtered water, (5) proper storage of the
treated water, and (6) proper maintenance of the entire water
system. Local authorities may be able to furnish advice on pond
development.
The value of a pond or lake development is its ability to store
water during wet periods for use during periods of little or no
rainfall. A pond should be capable of storing a minimum of 1 year's
supply of water. It must be of sufficient capacity to meet water
supply demands during periods of low rainfall with an additional
allowance for seepage and evaporation losses. The drainage area
(watershed) should be large enough to catch sufficient water to fill
the pond or lake during wet seasons of the year.
Careful consideration of the location of the watershed and pond
site reduces the possibility of chance contamination.
The watershed should:
1. Be clean, preferably grassed.
2. Be free from barns, septic tanks, privies, and soil-absorption
fields.
3. Be effectively protected against erosion and drainage from
livestock areas.
4. Be fenced to exclude livestock.
The pond should:
1. Be not less than 8 feet deep at deepest point.
2. Be designed to have the maximum possible water storage
area over 3 feet in depth.
3. Be large enough to store at least 1 year's supply.
4. Be fenced to keep out livestock.
5. Be kept free of weeds, algae, and floating debris.
In many instances pond development requires the construction of
an embankment with an overflow or spillway. Assistance in
designing a storage pond may be available from Federal, State, or
local health agencies; the U.S. Soil Conservation Service; and in
publications from the State or county agricultural, geological, or
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soil conservation departments. For specific conditions, engineering
or geological advice may be needed.
Intake. A pond intake must be properly located in order that it
may draw water of the highest possible quality. When the intake is
placed too close to the pond bottom, it may draw turbid water or
water containing decayed organic material. When placed too near
the pond surface, the intake system may draw floating debris, algae,
and aquatic plants. The depth at which it operates best will vary,
depending upon the season of the year and the layout of the pond.
The most desirable water is usually obtained when the intake is
located between 12 and 18 inches below the water surface. An
intake located at the deepest point of the pond makes maximum
use of stored water.
Pond intakes should be of the type illustrated in figure 13. This is
known as a floating intake. The intake consists of a flexible pipe
attached to a rigid conduit which passes through the pond
embankment.
In accordance with applicable specifications, gate valves should
be installed on the main line below the dam and on any branch line
to facilitate control of the rate of discharge.
Treatment. The pond water-treatment facility consists of four
general parts. (See fig. 14.)
1. Settling Basin. The first unit is a settling basin. The purpose
of the basin is to allow the large particles of turbidity to settle. This
may be adequately accomplished in the pond. When this is not
completely effective, a properly designed settling basin with
provision for coagulation may be needed. The turbid water is mixed
with a suitable chemical such as alum. Alum and other chemical
aids speed up the settling rate of suspended materials present in the
water. This initial process helps to reduce the turbidity of the water
to be passed through the filter. Addition of alum will lower the pH,
which may have to be readjusted with lime if corrosion of the
distribution piping results.
2. Filtration Unit. After settling, the water moves to a second
compartment where it passes through a filter bed of sand and
gravel. The suspended particles which are not removed by
settlement or flocculation are now removed.
3. Clear Water Storage. After the water leaves the filter, it drains
into a clear well, cistern, or storage tank.
4. Disinfection. After water has settled and has been filtered it
must be disinfected. Proper disinfection is the most important part
of pond-water treatment. The continuous operation and
high-quality performance of the equipment are very important. The
different types of equipment and processes are described in detail in
part IV. When the water is chlorinated, livestock unaccustomed to
chlorinated water may refuse to drink the water for several days.
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"O
I
w
a!
1
Cb
-------
Pressure Tank -
Hand
Valve
Automatic Chlorinator
Automatic Jet Pump
Pumphouse
Reinforced Concrete Top rReinforced Concrete Top
Hand Valve
Reinforced
Concrete Cover
Purified Water to House
(Below Frost Line)
Washed River Sand
Screened Through 1/8" Sieve
FM.TER
To Water Coagulation &
Source Sedimentation Chamber
Concentric Piping with Outer
Pipe under System Pressure
FIGURE 14. Schematic diagram of pond water-treatment system.
They usually become accustomed to it within a short period of
time.
Bacteriological Examination. After the treatment and
disinfection equipment have been checked and are operating
satisfactorily, a bacteriological examination of a water sample
should be made. Before a sample is collected, the examining
laboratory should be contacted for its recommendations. These
recommendations should include the type of container to be used
and the method and precautions to take during collection, handling,
and mailing. When no other recommendations are available, follow
those given in appendix B.
Water should not be used for drinking and culinary purposes until
the results of the bacteriological examination show the water to be
safe.
The frequency of subsequent bacteriological examinations should
be based on any breakdown or changes made in the sanitary
construction or protective measures associated with the supply. A
daily determination and record of the chlorine residual is
recommended to insure that proper disinfection is accomplished.
Plant Maintenance. The treatment facility should be inspected
daily. The disinfection equipment should be checked to make sure
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it is operating satisfactorily. When chlorine disinfection is practiced,
the chlorinator and the supply of chlorine solution should be
checked. The water supply should be checked daily for its chlorine
residual. The water may become turbid after heavy rains and the
quality may change. Increases in the amount of chlorine and
coagulants used will then be required. The performance of the filter
should be watched closely. When the water becomes turbid or the
available quantity of water decreases, the filter should be cleaned or
backwashed.
Protection From Freezing. Protection against freezing must be
provided unless the plant is not operated and is drained during
freezing weather. In general, the filter and pumproom should be
located in a building that can be heated in winter. With suitable
topography the need for heat can be eliminated by placement of
the pumproom and filter underground on a hillside. Gravity
drainage from the pumproom must be possible to prevent flooding.
No matter what the arrangement, the filter and pumproom must be
easily accessible for maintenance and operation.
Tastes and Odors. Surface water frequently develops musty or
undesirable tastes and odors. These are generally caused by the
presence of microscopic plants called algae. There are many kinds
of algae. Some occur in long threadlike filaments that are visible as
large green masses of scum; others may be separately free floating
and entirely invisible to the unaided eye. Some varieties may grow
in great quantities in the early spring, others in summer, and still
others in the fall. Tastes and odors generally result from the decay
of dead algae. This decay occurs naturally as plants pass through
their life cycle. For additional discussion, see "Control of Algae" in
part IV.
Tastes and odors in water can usually be satisfactorily removed
by passing the previously filtered and chlorinated surface water
through an activated carbon filter. These filters may be helpful in
improving the taste of small quantities of previously treated water
used for drinking or culinary purposes. They also absorb excess
chlorine. Carbon filters are commercially available, and require
periodic servicing.
Carbon filters should not be expected to be a substitute for sand
filtration and disinfection. They have insufficient area to handle
raw surface water and will clog very rapidly when filtering turbid
water.
Weed Control. The growth of weeds around a pond should be
controlled by cutting or pulling. Before weedkillers are used, the
local health department should be contacted for advice since
herbicides often contain compounds that are highly toxic to
humans and animals. Algae in the pond should be controlled,
particularly the blue-green types that produce scum and
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objectionable odors and that, in unusual instances, may harm
livestock. (See pt. IV.)
Streams
Streams receiving runoff from large uncontrolled watersheds may
be the only source of water supply. The physical and bacteriological
quality of surface water varies and may impose unusually or
abnormally high loads on the treatment facilities.
Stream intakes should be located upstream from sewer outlets or
other sources of contamination. The water should be pumped when
the silt load is low. A low-water stage usually means that the
temperature of the water is higher than normal and the water is of
poor chemical quality. Maximum silt loads, however, occur during
maximum runoff. High-water stages shortly after storms are usually
the most favorable for diverting or pumping water to storage. These
conditions vary and should be determined for the particular stream.
Irrigation Canals
If properly treated, irrigation water may be used as a source of
domestic water supply. Water obtained from irrigation canals
should be treated the same as water from any other surface-water
source. For additional information, see part IV.
When return irrigation (tail water) is practiced, the water may
contain large concentrations of undesirable chemicals, including
pesticides, herbicides, and fertilizer. Whenever water from return
irrigation is used for domestic purposes, a periodic chemical analysis
should be made. Because of the poor quality of this water, it should
only be used if no other water source is available.
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PartIV
Water Treatment
NEED AND PURPOSE
Raw waters obtained from natural sources may not be
completely satisfactory for domestic use. Surface waters may
contain pathogenic (disease-producing) organisms, suspended
matter, or organic substances. Except in limestone areas, ground
water is less likely to have pathogenic organisms than surface water,
but may contain undesirable tastes and odors or mineral impurities
limiting its use or acceptability. Some of these objectionable
characteristics may be tolerated temporarily, but it is desirable to
raise the quality of the water to the highest possible level by
suitable treatment. In those instances where the nearly ideal water
can be developed from a source, it is still advisable to provide the
necessary equipment for treatment to insure safe water at all times.
The quality of surface water constantly changes. Natural
processes which affect water quality are the dissolving of minerals,
sedimentation, filtration, aeration, sunlight, and biochemical
decomposition. Natural processes may tend to pollute and
contaminate or to purify the water; however, the natural processes
of purification are not consistent or reliable.
Bacteria which are numerous in waters at or near the earth's
surface may be reduced by soil filtration, depletion of available
oxygen, or underground detention for long periods under
conditions unfavorable for bacterial growth or survival. When water
flows through underground fissures or channels, however, it may
retain contamination over long distances and for extended periods
of time.
The false belief that flowing water purifies itself after traveling
various distances has led to unjustified feelings of security about its
safety. Under certain conditions the number of micro-organisms in
flowing surface water may increase instead of decrease.
Water treatment incorporates, modifies, or supplements certain
natural processes. This provides adequate assurance that the water is
free from pathogenic organisms or other undesirable materials or
chemicals. Water treatment may condition or reduce to acceptable
levels any chemicals or esthetically objectionable impurities which
may be present in the water.
Some of the natural treatment processes and manmade
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adaptations to improve and condition water are discussed in the
following sections.
SEDIMENTATION
Sedimentation is a process of gravity settling and deposition of
comparatively heavy suspended material in water.
This settling action can be accomplished in a quiescent pond or
properly constructed tank or basin. At least 24 hours' detention
time must be provided if a significant reduction in suspended
matter is to be accomplished. The inlet of the tank should be
arranged so that the incoming water containing suspended matter is
distributed uniformly across the entire width as the water flows to
the outlet located at the opposite end. Baffles are usually
constructed to reduce high local velocities and short circuiting of
the water. The cleaning and repairing of an installation can be
facilitated by the use of a tank designed with two separated
sections, each of which may be used independently.
COAGULATION-FLOCCULATION
Coagulation is the process of forming flocculent particles in a
liquid by the addition of a chemical. Coagulation is achieved by
adding to the water a chemical such as alum (hydrated aluminum
sulfate). The chemical is mixed with the turbid water and then
allowed to remain quiet. The suspended particles will combine
physically and form a floe. The floe or larger particles will settle to
the bottom of the basin. This may be done in a separate tank or in
the same tank after the mixing has been stopped. Adjustment of pH
may be required after sedimentation. Some colors can be removed
from water by using proper coagulation techniques. Competent
engineering advice, however, should be obtained on specific
coagulation problems.
FILTRATION
Filtration is the process of removing suspended matter from
water as it passes through beds of porous material. The degree of
removal depends on the character and size of the filter media, the
thickness of the porous media, and the size and quantity of the
suspended solids. Since bacteria can travel long distances through
granular materials, filters should not be relied upon to produce
bacteriologically safe water, even though they may greatly improve
the quality. When a water source contains a large amount of
turbidity, a large portion of it can first be removed by
sedimentation. A protected pond with gentle grassy slopes is often
helpful in producing a reasonably clear raw water. This action will
reduce the load placed on the filters.
Types of filters that may be used include:
Slow Sand Filters. Water passes slowly through beds of fine sand
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at rates averaging 0.05 gallon per minute per square foot of filter
area.
Pressure Sand Filters. Water is applied at a rate at or above 2
gallons per minute per square foot of filter area with provisions
made for frequent backwashing of the filters.
Diatomaceous Earth Filters. Suspended solids are removed by
passing the water through a layer of diatomaceous filter media
supported by a rigid base septum at rates approximately that of
pressure sand filters.
Porous Stone, Ceramic, or Unglazed Porcelain Filters (Pasteur
Filters). These are small household filters that are attached to
faucets.
Properly constructed slow sand filters require a minimum of
maintenance and can be easily adapted to individual water systems.
The length of time between cleaning will vary from a day to a week
or month; the length of the interval depends upon the turbidity of
the water. After an interval it is necessary to clean the filter by
removing approximately 1 inch of sand from the surface of the
filter and either discarding it or stockpiling it for subsequent
washing and reuse. This removal will necessitate the periodic
addition of new or washed sand.
Sand for slow sand filters should consist of hard, durable grains
free from clay, loam, dirt, and organic matter. It should have a sieve
analysis which falls within the range of values shown in table 6.
TABLE6. — Recommended mechanical analysis of slow sand filter media
Material passing sieve
(percent)
99
90-97
75-90
60-80
U.S. sieve
no.
4
12
16
20
Material passing sieve
(percent)
33-55
17-35
4-10
1
U.S. sieve
no.
30
40
60
100
Sands with an effective size of 0.20 to 0.40 millimeter are
satisfactory. The effective size is the size of the grain in millimeters,
such that 10 percent of the material, by weight, is of a smaller size.
The uniformity coefficient should be between 2.0 and 3.0. The
uniformity coefficient is taken as the ratio of the grain size that has
60 percent finer than itself to the size that has 10 percent finer than
itself.
For best results the rate of filtration for a slow sand filter should
be 60 to 180 gallons per day per square foot of filter bed surface.
The amount of water that flows through the filter bed can be
adjusted by a valve placed on the effluent line. Between 27 and 36
inches of sand, with an additional 6 to 12 inches that can be
removed during cleaning, is usually sufficient. Six to 8 inches of
gravel will support the sand and keep it out of the underdrain
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system. A 1%-inch plastic pipe drilled with 3/4-inch holes facing
down makes a convenient underdrain system. One to 2 feet of
freeboard on the top of the filter is usually sufficient.
Rapid sand filtration is not usually desirable for small individual
water supplies because of the necessary controls and additional
attention required to obtain satisfactory results. When adequate
operation and supervision are provided, pressure sand filtration can
be used successfully.
Diatomaceous earth filters, which require periodic attention, are
of two types — vacuum or pressure. These filters are effective when
properly operated and maintained.
The effectiveness of filtration is monitored by measurement of
turbidity, a light-scattering property of particles suspended in
water. Filtered water must contain low turbidity if adequate
disinfection is to be accomplished.
The possibility must be considered that dirty stone or ceramic
faucet filters may attract bacteria and provide a place for their
multiplication or that these filters may develop hairline cracks. For
these reasons, small household faucet filters cannot be depended
upon to remove pathogenic bacteria, and their use is not
recommended for producing bacteriologically safe water.
Small pad, spool, or wad coarse filters may be useful for
low-capacity, coarse filtration for removal of large suspended
particles only. Proper disinfection of water before consumption is
necessary to assure its safety.
DISINFECTION
The most important water treatment process is disinfection.
Disinfection is necessary to destroy all pathogenic bacteria and
other harmful organisms that may be present in water. If complete
destruction of these organisms is to be accomplished, the water to
which the disinfectant is added must be low in turbidity. After
disinfection, water must be kept in suitable tanks or other storage
facilities to prevent recontamination.
Chemical Disinfection
The desirable properties for a chemical disinfectant are high
germicidal power, stability, solubility, nontoxicity to man or
animals, economy, dependability, residual effect, ease of use and
measurement, and availability.
Compounds of chlorine most satisfactorily comply with the
desirable properties of a chemical disinfectant; and as a result,
chlorine is the most commonly used water disinfectant.
Disinfectant Terminology
1. Chlorine concentration. This is expressed in milligrams per
liter (mg/2). One mg/£ is equivalent to 1 milligram of
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chlorine in 1 liter of water. For water, the terms parts per
million (ppm) and mg/2 are essentially equal.
2. Chlorine feed or dosage. The actual amount in mg/£ fed
into the water system by feeder or automatic dosing
apparatus is the chlorine feed or dosage.
3. Chlorine demand. The chlorine fed into the water that
combines with the impurities, and, therefore, may not be
available for disinfection action, is commonly called the
chlorine demand of the water. Examples of impurities
causing chlorine demand are organic materials and certain
"reducing" materials such as hydrogen sulfide, ferrous
iron, nitrites, etc.
4.Free and combined chlorine. In addition to organic
materials that exert a chlorine demand, chlorine can
combine with ammonia nitrogen, if any is present in the
water, to form chlorine compounds that have some biocidal
properties. These chlorine compounds are called combined
chlorine residual. If no ammonia is present in the water,
however, the chlorine that remains in the water once the
chlorine demand has been satisfied is called free chlorine
residual.
5. Chlorine contact time. The chlorine contact time is the
period of time that elapses between the time when the
chlorine is added to the water and the time when that
particular water is used. Contact time is required for
chlorine to act as a disinfectant.
Chlorine Disinfection
In general, the primary factors that determine the biocidal
efficiency of chlorine are as follows:
I. Chlorine concentration. The higher the concentration, the
more effective the disinfection and the faster the
disinfection rate.
2. Type of chlorine residual. Free chlorine is a much more
effective disinfectant than combined chlorine.
3. Contact time between the organism and chlorine. The
longer the time, the more effective the disinfection.
4. Temperature of the water in which contact is made. The
higher the temperature, the more effective the
disinfection.
5. The pH of the water in which contact is made. The lower
the pH, the more effective the disinfection.
Chlorine dosage should be great enough to satisfy the chlorine
demand and provide a residual of 0.4 mg/£ after a chlorine contact
time of 30 minutes or a combined residual of 2.0 mg/£ with a
2-hour contact time. Hypochlorinators pump or inject a chlorine
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solution into the water, and, when they are properly maintained,
provide a reliable method for applying chlorine. Hypochlorinators
and chlorine residual test equipment are available from several
manufacturers through local dealers.
Chlorine Compounds and Solutions
Compounds of chlorine such as sodium or calcium hypochlorite
have excellent disinfecting properties. In small water systems these
chlorine compounds are usually added to the water in a solution
form.
One of the commonly used forms of chlorine is calcium
hypochlorite. It is commercially available in the form of soluble
powder or tablets. These compounds are classed as high-test
hypochlorites and contain 65 to 75 percent available chlorine by
weight. Packed in cans or drums, these compounds are stable and
will not deteriorate if properly stored and handled.
Prepared sodium hypochlorite solution is available locally
through chemical or swimming pool equipment suppliers. The most
common type is household chlorine bleach which has a strength of
approximately 5 percent available chlorine by weight. Other sodium
hypochlorite solutions vary in strength from 3 to 15 percent
available chlorine by weight, and are reasonably stable when stored
in a cool, dark place. These solutions are diluted with potable water
to obtain the desired solution strength to be fed into the system.
When hypochlorite powders are used, fresh chlorine solutions
should be prepared at frequent intervals because the strength of
chlorine solutions deteriorates gradually after preparation. The
container or vessel used for preparation, storage, or distribution of
the chlorine solution should be resistant to corrosion and light.
(Light produces a photochemical reaction that reduces the strength
of chlorine solutions.) Suitable materials include glass, plastic,
crockery, or rubber-lined metal containers.
Hypochlorite solutions are used either full strength as prepared or
are diluted to solution strength suited to the feeding equipment and
the rate of water flow. In preparing these solutions, one must take
into account the chlorine content of the concentrated solution. For
example, if 5 gallons of 2 percent solution are to be prepared with a
high-test calcium hypochlorite powder or tablet containing 70
percent available chlorine, the high-test hypochlorite would weigh
1.2 pounds.
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Pounds of compound required
% strength x gallons solution „ „ ~
_ of solution required
% available chlorine in compound
= 2X5X8.3
70
= 1.2 pounds
Expressed in another way, 1.2 pounds of high-test hypochlorite
with 70 percent available chlorine would be added to 5 gallons of
water to produce a 2-percent chlorine solution.
Determination of Chlorine Residual
Residual chlorine can exist in water as a chlorine compound of
organic matter and ammonia or as both combined and free available
chlorine residual. When present as a chlorine compound, it is called
combined available chlorine residual, as free chlorine it is known as
free available chlorine residual, and as both combined and free
available chlorine it is called total available chlorine residual. Thus,
"sufficient chlorine" is that amount required to produce a desired
residual after a definite contact period, whether combined, free, or
total.
The amount of chlorine remaining (chlorine residual) in the water is
determined by a relatively simple test commonly called the DPD colori-
metric test, short for the chemical name N,N-diethyl-p-phenylene-diam-
ine. The test may be done under "field" conditions, using pill reagents
that are placed in a special test tube. The presence of free chlorine
residual produces a violet color that can be compared with color
standards to determine the quantity present. The kits, complete with all
necessary tubes, chemicals, color standards and instructions, can be
obtained from firms that specialize in the manufacture of water testing
equipment and materials. A combination DPD and pH kit is available; its
modest price makes it a good investment. State and county water supply
agencies can provide the names of kits they consider acceptable.
Wherever chlorination is required for disinfection, testing for chlorine
residual should be done at least daily.
For those desiring more information on the DPD test, a description is
included in Standard Methods for the Examination of Water and
Wastewater.l
Obtainable from the American Public Health Association, 1015 Fifteenth Street, NW.,
Washington, D.C. 20036
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Chlorination Equipment
Hypo chlorina tors
Hypochlorinators pump or inject a chlorine solution into the
water. When they are properly maintained, hypochlorinators
provide a reliable method for applying chlorine to disinfect water.
Types of hypochlorinators include positive displacement feeders,
aspirator feeders, suction feeders, and tablet hypochlorinators.
Positive Displacement Feeders. A common type of positive
displacement hypochlorinator is one that uses a piston or
diaphragm pump to inject the solution. This type of equipment,
which is adjustable during operation, can be designed to give
reliable and accurate feed rates. When electricity is available, the
stopping and starting of the hypochlorinator can be synchronized
with the pumping unit. A hypochlorinator of this kind can be used
with any water system; however, it is especially desirable in systems
where water pressure is low and fluctuating.
Aspirator Feeders. The aspirator feeder operates on a simple
hydraulic principle that employs the use of the vacuum created
when water flows either through a venturi tube or perpendicular to
a nozzle. The vacuum created draws the chlorine solution from a
container into the chlorinator unit where it is mixed with water
passing through the unit, and the solution is then injected into the
water system. In most cases, the water inlet line to the chlorinator
is connected to receive water from the discharge side of the water
pump, with the chlorine solution being injected back into the
suction side of the same pump. The chlorinator operates only when
the pump is operating. Solution flow rate is regulated by means of a
control valve, though pressure variations may cause changes in the
feed rate.
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Suction Feeders. One type of suction feeder consists of a single
line that runs from the chlorine solution container through the
chlorinator unit and connects to the suction side of the pump. The
chlorine solution is pulled from the container by suction created by
the operating water pump.
Another type of suction feeder operates on the siphon principle,
with the chlorine solution being introduced directly into the well.
This type also consists of a single line, but the line terminates in the
well below the water surface instead of the influent side of the
water pump. When the pump is operating, the chlorinator is
activated so that a valve is opened and the chlorine solution is
passed into the well.
In each of these units, the solution flow rate is regulated by
means of a control valve and the chlorinators operate only when the
pump is operating. The pump circuit should be connected to a
liquid level control so that the water supply pump operation is
interrupted when the chlorine solution is exhausted.
Tablet Hypochlorinators. The tablet hypochlorinating unit
consists of a special pot feeder containing calcium hypochlorite
tablets. Accurately controlled by means of a flowmeter, small jets
of feed water are injected into the lower portion of the tablet bed.
The slow dissolution of the tablets provides a continuous source of
fresh hypochlorite solution. This unit controls the chlorine
solution. This type of chlorinator is used when electricity is not
available, but requires adequate maintenance for efficient
operation. It can operate where the water pressure is low.
Gaseous Feed Chlorinators
In installations where large quantities of water are treated,
chlorine gas in pressure cylinders may be used as the disinfectant.
The high cost of this type of chlorination equipment and the safety
precautions necessary to guard against accidents do not usually
justify its use in individual water supply systems.
Solution Supply Monitor
Sensing units which can be placed in solution containers to sound
a warning alarm when the solution goes below a predetermined level
are commercially available. This equipment can also be connected
to the pump, which will automatically shut off the pump and
activate a warning bell. On such a signal the operator will be
required to refill the solution container and take necessary steps to
insure proper disinfection.
Chlorination Control
As indicated previously, several factors pertaining to a water
supply system have a direct bearing on the effectiveness of chlorine.
Because of these variable factors, it is not possible to suggest rigid
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standards of chlorine disinfection applicable to all water supply
systems. It is considered desirable, however, to suggest the
following practice in this regard for the guidance of persons
responsible for water supply operation and maintenance.
Simple Chlorination
Unless bacteriological or other tests indicate the need for
maintaining higher minimum concentrations of free residual
chlorine, at least 0.4 mg/£ of free residual chlorine (see p. 77)
should be in contact with the treated water for not less than 30
minutes before the water reaches the first user beyond the point of
chlorine application. It is considered desirable to maintain a
detectable free chlorine residual at distant points in the distribution
system when using simple chlorination; however, the water can be
properly disinfected if a minimum contact time of 30 minutes is
assured.
A method known as superchlorination-dechlorination is suggested
for use in overcoming and simplifying the problem of insufficient
contact time in such water systems. By this method chlorine is
added to the water in increased amounts (superchlorination) to
provide a minimum chlorine residual of 3.0 mg/£ for a minimum
contact period of 5 minutes. Removal of the excess chlorine
(dechlorination) follows to eliminate objectionable chlorine tastes.
Dechlorination equipment is commercially available.
Records
Adequate control is also dependent on the maintenance of
accurate operating records of the chlorination process. The record
should serve as an indicator that proper chlorination is being
accomplished and as a guide in improving operations. The record
should show the amount of water treated, amount of chlorine used,
setting of the chlorinator, time and location of tests, and results of
chlorine residual determinations. This information should be kept
current and posted near the chlorinator.
Disinfection With Ultraviolet Light
Ultraviolet (UV) light produced from UV lamps has been shown
to be an effective bactericide for both air and water. In disinfecting
water, the quantity of radiation required is dependent on such
factors as turbidity, color, and dissolved iron salts, which adversely
affect the penetration of ultraviolet energy through the water. UV
light would not be satisfactory for disinfecting water with high
turbidity.
Cylindrical units with standard plumbing fittings have been de-
signed for use in waterlines. They should be checked frequently for
light intensity and cleaned of any material that would block radia-
tion from reaching the water. A disadvantage of UV light is that it
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does not provide a residual in the water as does chlorine. Thus,
there is no barrier against recontamination in UV-disinfected water.
Also, an uninterrupted source of electric power is needed for UV
units. The counsel of the State health authority should be obtained
before selecting a particular unit for installation.
Other Methods and Materials for Water Disinfection
A number of other materials and methods are used for
disinfecting water. Some of these are as follows:
1. Organic chlorine-yielding compounds
2. Bromine
3. Iodine and iodine-yielding organics
4. Ozone
5. Hydrogen peroxide and peroxide-generating compounds
6. Silver
7. Nontoxic organic acids
8. Lime and mild alkaline agents
9. Ultrasonic cavitation
10. Heat treatment
Some of these are old processes on which detailed studies have
been made; others are relatively new.
When a question of specific application arises, the recommenda-
tions of the State or local health department should be followed.
CONDITIONING
Iron and/or Manganese
The presence of iron and/or manganese in water creates a
problem common to many individual water supply systems. When
both are present beyond applicable drinking water standards,
special attention should be given. Their removal or elimination
depends somewhat on type and quantity, and this influences the
procedure and possibly the equipment to be used.
Well water is usually clear and colorless when drawn from the
faucet or tap. When water containing colorless, dissolved iron is
allowed to stand in a cooking container or comes in contact with a
sink or bathtub, the iron combines with oxygen from the air to
form a reddish-brown precipitate commonly called rust. Manganese
acts in a similar manner, but forms a brownish-black precipitate.
These impurities can impart a metallic taste to the water or to
any food in whose preparation such a supply is used. Deposits of
iron and manganese produce rusty or brown stains on plumbing
fixtures, fabrics, dishes, or utensils. The use of soaps or detergents
will not remove these stains, and bleaches and alkaline builders
(often sodium phosphate) can intensify the staining. After a
prolonged period, iron deposits can build up in pressure tanks,
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water heaters, and pipelines. This buildup reduces the available
quantity and pressure of the water supply.
Iron and manganese can be removed by a combination of
automatic chlorination and fine filtration. The chlorine chemically
oxidizes the iron or manganese (forming a precipitate), kills iron
bacteria, and eliminates any disease bacteria which may be present.
The fine filter then removes the iron or manganese precipitates.
Other techniques, such as aeration followed by filtration, ion
exchange with greensand, or treatment with potassium
permanganate followed by filtration, will also remove
these materials.
Some filters may dechlorinate also. This chlorination-filtration
method provides complete correction of such problems and assures
disinfection as well.
Insoluble iron or manganese and iron bacteria will intensely
"foul" the mineral bed and the valving of a water softener. It is
best, therefore, to remove iron and manganese before the water
reaches the softener.
When a backwash filter medium is used it is essential that an
adequate quantity of water at sufficient pressure be provided for
removing the iron precipitate.
Iron Bacteria
Under certain conditions the removal of iron compounds from a
water supply may be complicated by the presence of iron bacteria.
When dissolved iron and oxygen are present in the water, these
bacteria derive the energy they need for their life processes from
the oxidation of the iron to its insoluble form. These products
accumulate within a gelatinous mass which coats submerged
surfaces. A slimy, rust-colored mass on the interior surface of flush
tanks or water closets indicates the presence of iron bacteria.
Iron bacteria can reduce the carrying capacity of water pipes by
increasing frictional losses. They may impart an unpleasant taste
and odor to the water or discolor and spot fabrics, plumbing
fixtures, and clog pumps. A detectable slime also builds up on any
surface with which the water containing these organisms comes in
contact. Iron bacteria may be concentrated in a specific location
and may periodically break loose and appear at the faucet in
detectable amounts of rust.
Iron-removal filters or water softeners can remove iron bacteria;
however, they often become clogged and fouled because of the
slime buildup. A disinfecting solution such as chlorine bleach
should be injected into the water to control the growth of iron
bacteria. Such a solution causes a chemical reaction which allows an
iron precipitate to form. This precipitate can be removed with a
suitable fine filter.
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Softening
Water softening is a process for the removal of the minerals,
primarily calcium and magnesium, which cause hardness.
Softening of hard water is desirable if
1. Large quantities of soap are needed to produce a lather.
2. Hard scale is formed on cooking utensils or laundry basins.
3. Hard, chalklike formations coat the interiors of piping or
water tanks.
4. Heat-transfer efficiency through the walls of the heating
element or exchange unit of the water tank is reduced.
The buildup of scale will cause an appreciable reduction in pipe
capacities and pressures. The appearance of excessive scale from
hard waters will also be esthetically objectionable. Experience has
shown that hardness values greatly in excess of 200 mg/£ (12 grains
per gallon) may cause some problems in the household.
Water may be softened by either the ion-exchange or the
lime-soda ash process, but both processes increase the sodium
content of the water and may make it unsuitable for people on a
low-sodium diet.
Ion Exchange
The ion-exchange process causes a replacement of the calcium or
magnesium ions by sodium ions. The process takes place when the
hard water containing calcium or magnesium compounds comes in
contact with an exchange medium. The materials used in the
process of ion exchange are insoluble, granular materials that
possess a unique property of ion exchange. Ion-exchange material
may be classed as follows: glauconite (or greensand); precipitated
synthetic, organic (carbonaceous), and synthetic resins; or gel
zeolites. The last two are the most commonly used for domestic
purposes.
The type of ion-exchange material used is determined by the type
of water treatment required. For example, when a sodium zeolite is
used to soften water by exchanging the sodium ion for calcium and
magnesium ions in the hard water, the zeolite sodium ions
eventually become of insufficient quantity to effect the exchange.
After a certain period of time determined by the exchange rate, the
exchange material must be regenerated. The sodium ion is restored
to the zeolite by passing a salt (NaCl) or brine solution through the
bed. The salt solution used must contain the same type of ions
which were displaced by the calcium and magnesium. The solution
causes a reversal of the ion-exchange process, restoring the exchange
material to its original condition.
The type of regenerating material or solution which must be used
depends upon the type of exchange material in the ion-exchange
column.
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The ion-exchange method of softening water is relatively simple
and can be easily adapted to the small or individual water supply
system. Only a portion of the hard water needs to be passed
through the softening process because the exchange process
produces water of zero hardness. The processed water can then be
mixed with the hard water in proportions to produce a final water
with a hardness between 50 to 80 mg/£ (3 to 5 grains per gallon).
Waters with a turbidity of more than 10 Jackson units (an arbitrary
measure of the light-scattering properties of suspended particles in
water) should be properly treated for removal to increase the
effectiveness and the efficiency of the softening process.
Ion-exchange softeners are commercially available for individual
water systems. Their capacities range from about 85,000 to
550,000 milligrams of hardness that can be removed for each cubic
foot of the ion-exchange material. Water softeners should be
installed only by responsible persons in strict accordance with the
instructions from the manufacturer and applicable codes. The
materials and workmanship should be guaranteed for a specified
period of time. First consideration in securing ion-exchange
water-softening equipment should be given to those companies
providing responsible servicing dealers permanently located within a
reasonable distance from the water supply system. Note: Zeolite
softening is not recommended if any of the water consumers, for
medical reasons, are on a restricted sodium diet.
Lime-Soda Ash Process
The use of the lime-soda ash process or the addition of other
chemicals is not practical for a small water supply system. Water
used for laundry purposes, however, may be softened at the time of
use by the addition of certain chemicals such as borax, washing
soda, trisodium phosphate, or ammonia. Commercial softening or
water conditioning compounds of unknown composition should
not be used in water intended for drinking or cooking until the
advice of the State or local health department is obtained regarding
their safety.
Fluoridation
The presence of trace quantities of fluoride in the diet has been
found beneficial in reducing dental caries in children and young
adults. Water is currently an economical medium through which
these trace quantities can be assimilated through body processes
into the enamel of the teeth.
Equipment for fluoridating even the smallest home water supplies
has been developed and used for several years. It is recommended,
however, that the installer maintain the home fluoridator and test
the treated water for fluoride level. It is an economical and reliable
means of providing fluoridated water if the operation and
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maintenance of the fluoridating equipment are combined with
other home water supply services; i.e., softening, iron removal,
chlorination, and the like.
When a question of specific application arises, the recommenda-
tions of the State or local health department should be followed.
Tastes and Odors
Tastes and odors present in an individual water supply system fall
into two general classes - natural and man made. Some natural
causes may be traced to the presence of or contact of water with
algae, leaves, grass, decaying vegetation, dissolved gases, and
slime-forming organisms. Some of the manmade causes of taste and
odor may be attributed to the presence of chemicals or sewage.
Water having a "rotten egg" odor indicates the presence of
hydrogen sulfide and is commonly referred to as sulfur water. In
addition to its objectionable odor, sulfur water may cause a black
stain on plumbing fixtures. Hydrogen sulfide is very corrosive to
common metals and will react with iron, copper, or silver to form
the sulfides of these metals.
Depending upon the cause, taste and odor can be removed or
reduced by aeration or by treatment with activated carbon, copper
sulfate, or an oxidizing agent such as chlorine.
Aeration is exposure of as much water surface as possible to the
air. It is described in the section entitled "Aeration." Hydrogen
sulfide can be removed by aeration or by a combination
oxidization-filtration process. A simple iron-removal filter will also
do a good job of removing this objectionable compound when small
amounts are involved.
The activated carbon treatment consists of passing the water to
be treated through granular carbon, or adding powdered activated
carbon to the water. Activated carbon adsorbs (attracts to itself)
large quantities of dissolved gases, soluble organics, and finely
divided solids. It is therefore extremely effective in taste and odor
control. Activated carbon can be used in carbon filters
commercially available from the manufacturers or producers of
water-conditioning or treatment equipment. The recommendations
included with the filter should be followed.
Copper Sulfate. The most frequent source of taste and odors in
an individual water supply system is algae. These minute plants
produce certain biological byproducts which cause tastes and odors
in the water. These tastes and odors may be accentuated when
chlorine is added to the water. When they are present in a water
supply their growth can be controlled by adding copper sulfate to
the water source, as described in the section dealing with "Algae
Control."
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Because algae and other chlorophyll-containing plants need
sunlight to grow, the storage of water in covered reservoirs inhibits
their growth.
Chlorine. Chlorine is an effective agent in reducing tastes and
odors present in water. The process used for the reduction of tastes
and odors is the same as described in the section dealing with
"Superchlorination-Dechlorination."
Corrosion Control
The control of corrosion is important not only to continuous and
efficient operation of the individual water system but also to
delivery of properly conditioned water that has not picked up trace
quantities of metals that may be hazardous to health. Whenever
corrosion is minimized there is an appreciable reduction in the
maintenance and possible replacement of water pipes, water
heaters, or other metallic appurtenances of the system.
Corrosion is commonly defined as an electrochemical reaction in
which metal deteriorates or is destroyed when in contact with
elements of its environment such as air, water, or soil. Whenever
this reaction occurs there is a flow of electric current from the
corroding portion of the metal toward the electrolyte or conductor
of electricity, such as water or soil. The point at which current
flows from the metal into the electrolyte is called the "anode" and
the point at which current flows away from the electrolyte is called
the "cathode." Any characteristic of the water which tends to allow
or increase the rate of this electrical current will increase the rate of
corrosion. The important characteristics of a water that affect its
corrosiveness include the following:
I.Acidity. A measure of the water's ability to neutralize
alkaline materials. Water with acidity or low alkalinity (a
measure of the concentration of alkaline materials) tends
to be corrosive.
2. Conductivity. A measure of the amount of dissolved
mineral salts. An increase in conductivity promotes flow
of electrical current and increases the rate of corrosion.
3. Oxygen content. Amount dissolved in water promotes
corrosion by destroying the thin protective hydrogen film
that is present on the surface of metals immersed in water .
4. Carbon dioxide. Forms carbonic acid, which tends to attack
metallic surfaces.
5. Water temperatures. The corrosion rate increases with water
temperature.
Corrosion and Scale Relationship
Corrosion and scale are associated problems, but their effect and
cause should not be confused. The essential effect of corrosion is to
destroy-.rne-tal;-scale, pn.thep.therfchaKdj tends to clog open sections
88 '• ."" •' "••A:~--: \-"'.'
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and line surfaces with deposits. The products of corrosion often
contribute to scale formation and aggravate the problem of its
treatment.
Prevention of Corrosion
When corrosion is caused by the acidity of the water supply, it
can be effectively controlled by installing an acid neutralizer ahead
of a water softener. Another method of controlling corrosion is that
of feeding small amounts of commercially available film-forming
materials such as polyphosphates or silicates. Other methods for
controlling corrosion are the installation of dielectric or insulating
unions, reduction of velocities and pressures, removal of oxygen or
acid constituents, chemical treatment to decrease the acidity, or the
use of nonmetallic piping and equipment.
pH Correction or Neutralizing Solution
The pH of water may be increased by feeding a neutralizing
solution so that it no longer attacks parts of the water system or
contributes to electrolytic corrosion. Neutralizing solutions may be
prepared by mixing soda ash (58% light grade) with water — 3
pounds soda ash to 4 gallons of water. This solution may be fed
into the water supply with feeders as described under
"Chlorination," and may be mixed with chlorine solutions to
accomplish both pH correction and disinfection with the same
equipment. Soda ash is available at chemical supply houses.
Nuisance Organisms
Organisms that have been known to cause problems in water supplies
include several species of algae, protozoa, and diatoms that produce
tastes and odors and clog filters. Iron bacteria plug water well intakes
and clog pipes in distribution systems (see Iron Bacteria, p. 84). Still
other nuisance organisms are copepods, whose eggs pass through filters;
midge larvae or bloodworms; and snails and mollusca. These organisms
vary in complexity and size. They are uncommon or absent in ground
water, but are common in surface waters.
Perhaps none of the organisms is injurious to health. Interference with
water treatment processes, and unpleasant taste, odor and appearance
constitute the chief complaints against them.
Control of Algae
Growths of algae can be controlled by treating the water with copper
sulfate (blue stone or blue vitriol) or, when feasible, by covering the
storage unit to exclude sunlight. Maintenance of an adequate chlorine
residual will effectively control the growth of algae and other organisms
wherever storage is covered and protected from contamination. The
particular control method, or combination of methods, is determined
by studying each case to a«fifS| theprpbabiiity for success and the costs
involved. UP etfdfogy ancf environment inc.
223 WEST JACKSON BLVD. oq
CHICAGO, IL 60606 (312) 663.9415
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Copper sulfate has been used successfully for the control of algae
since 1900. Temperature, pH and alkalinity all affect the solubility of
copper in water. From this it can be seen that the dosage required de-
pends on the chemistry of the water treated and the susceptibility to
copper of the particular nuisance organism present. Dosage rates of 1
ounce of copper sulfate (CuSO4-5H2O) for each 25,000 gallons of water
have proven effective where the total alkalinity of the water does not
exceed 40 mg/1 (40 ppm). For more alkaline waters, the dosage can be
increased to 5.5 pounds of copper sulfate per acre of surface water
treated regardless of depth.
Frequency of treatment depends on temperature, amount of sunlight,
and nutrients in the water. Systematic application of the calculated
amount of chemical over the entire surface area ensures that serious
algal blooms do not reappear. Several treatments per season are gen-
erally required, with treatments as frequent as twice a month during the
growing season not being unusual.
The most practical method of application for small ponds is by spray-
ing a solution on the surface. Or, a burlap bag of copper sulfate can be
dragged through the water. Rapid and uniform distribution of the chemi-
cal is important.
It should be noted that sudden kill of heavy growths of algae may be
followed by decomposition on a scale that depletes the oxygen content
of the water. If the removal of oxygen is excessive, a fish kill may result.
Any chemical applied to control a problem with nuisance organisms
must be used with caution. The concentrations recommended above will
affect only a portion of the biotic system. Excessive amounts of chemi-
cal may endanger other life systems in the environment. If there is any
doubt about the effects which treatment might have on other life sys-
tems, advice should be sought from responsible environmental agencies.
Aeration
Aeration is the process of bringing about the intimate contact
between air and a liquid such as water.
Many methods are available for obtaining effective aeration,
including spraying water into the air, allowing water to fall over a
spillway in a turbulent stream, or distributing water in multiple
streams Or droplets through a series of perforated plates. Although
the aeration of water may be accomplished in an open system,
adequate precautions should be exercised to eliminate possible
external contamination of the water. Whenever possible, a totally
enclosed system should be provided.
Aeration may be used to oxidize iron or manganese and remove
odors from water, such as those caused by hydrogen sulfide and
algae. It is also effective in increasing the oxygen content of water
deficient in dissolved oxygen. The flat taste of cistern water and
90
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distilled water may be improved by adding oxygen. Carbon dioxide
and other gases that increase the corrosiveness of water can be
eliminated largely by effective aeration, although the increase in
corrosion because of increased oxygen may partially offset the
advantage of the decrease in carbon dioxide.
Aeration of water results in partial oxidation of its dissolved iron
or manganese and thereby changes the iron into an insoluble form.
Sometimes a short period of storage permits the insoluble material
to settle; at other times the precipitated iron or manganese cannot
be removed successfully except by filtration.
A simple cascade device or a coke tray (wire-bottom trays filled
with activated carbon) aerator can be incorporated into a water
supply system. In addition to aerating, the coke tray will reduce
tastes and odors.
Insects such as the chironomus fly may lay eggs in the stagnant
portion of the aerator tray. The eggs develop into small red worms,
which is the larvae stage of this insect. Proper encasement of the
aerator prevents the development of this situation. Adequate
screening will provide, in addition, protection from windblown
debris.
91
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PartV
Pumping, Distribution,
and Storage
PUMPING
Types of Well Pumps
Three types of pumps are commonly used in individual water
distribution systems. They are the positive displacement, the
centrifugal, and the jet. These pumps can be used in a water system
utilizing either a ground or surface source. It is desirable in areas
where electricity or other power (gasoline, diesel oil, or windmill) is
available to use a power-operated pump. When a power supply is
not available, a hand pump or some other manual method of
supplying water must be used.
Special types of pumps with limited application for individual
water-supply systems include air lift pumps and hydraulic rams.
Positive Displacement Pumps
The positive displacement pump forces or displaces the water
through a pumping mechanism. These pumps are of several types.
One type of positive displacement pump is the reciprocating
pump. This pump consists of a mechanical device which moves a
plunger back and forth in a closely fitted cylinder. The plunger is
driven by the power source, and the power motion is converted
from a rotating action to a reciprocating motion by the combined
work of a speed reducer, crank, and a connecting rod. The cylinder,
composed of a cylinder wall, plunger, and check valve, should be
located near or below the static water level to eliminate the need
for priming. The pumping action begins when the water enters the
cylinder through a check valve. When the piston moves, the check
valve closes, and in so doing forces the water through a check valve
in the plunger. With each subsequent stroke, the water is forced
toward the surface through the discharge pipe.
Another type of positive displacement pump is the helical or
spiral rotor. The helical rotor consists of a shaft with a helical
(spiral) surface which rotates in a rubber sleeve. As the shaft turns,
it pockets or traps the water between the shaft and the sleeve and
forces it to the upper end of the sleeve.
Other types of positive displacement pumps include the
regenerative turbine type. It incorporates a rotating wheel or
impeller which has a series of blades or fins (sometimes called
93
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buckets) on its outer edge and a stationary enclosure called a
raceway or casting. Pressures several times that of pumps relying
solely on centrifugal force can be developed.
Centrifugal Pumps
Centrifugal pumps are pumps containing a rotating impeller
mounted on a shaft turned by the power source. The rotating
impeller increases the velocity of the water and discharges it into a
surrounding casing shaped to slow down the flow of the water and
convert the velocity to pressure. This decrease of the flow further
increases the pressure.
Each impeller and matching casing is called a stage. The number
of stages necessary for a particular installation will be determined
by the pressure needed for the operation of the water system, and
the height the water must be raised from the surface of the water
source.
When the pressure is more than can be practicably or
economically furnished by a single stage, additional stages are used.
A pump with more than one stage is called a multistage pump. In a
multistage pump water passes through each stage in succession, with
an increase in pressure at each stage.
Multistage pumps commonly used in individual water systems are
of the turbine and submersible types.
Turbine Pumps. The vertical-drive turbine pump consists of one
or more stages with the pumping unit located below the drawdown
level of the water source. A vertical shaft connects the pumping
assembly to a drive mechanism located above the pumping
assembly. The discharge casing, pumphousing, and inlet screen are
suspended from the pump base at the ground surface. The weight of
the rotating portion of the pump is usually suspended by a thrust
bearing located in the pump head. The intermediate pump bearings
may be lubricated by either oil or water. From a sanitary point of
view, lubrication of pump bearings by water is preferable, since
lubricating oil may leak and contaminate the water.
Submersible Pumps. When a centrifugal pump is driven by a
closely coupled electric motor constructed for submerged operation
as a single unit, it is called a submersible pump. (See fig. 15.) The
electrical wiring to the submersible motor must be waterproof. The
electrical control should be properly grounded to minimize the
possibility of shorting and thus damaging the entire unit. The pump
and motor assembly are supported by the discharge pipe; therefore,
the pipe should be of such size that there is no possibility of
breakage.
The turbine or submersible pump forces water directly into the
distribution system; therefore, the pump assembly must be located
below the maximum drawdown level. This type of pump can deliver
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Power Cable
Drop Pipe Connection
-Check Valve
- Pump Casing
'Inlet Screen
Diffusers 8 Impellers'
1 Inlet Body
Power Leads
Motor Shaft
' Motor Section
Lubricant Seal
F IGURE 15. Exploded view of submersible
pump.
95
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water across a wide range of pressures with the only limiting factor
being the size of the unit and the horsepower applied. When sand is
present or anticipated in the water source, special precautions
should be taken before this type of pump is used since the abrasion
action of the sand during pumping will shorten the life of the
pump.
Jet (Ejector) Pumps
Jet pumps are actually combined centrifugal and ejector pumps.
A portion of the discharged water from the centrifugal pump is
diverted through a nozzle and venturi tube. A pressure zone lower
than that of the surrounding area exists in the venturi tube;
therefore, water from the source (well) flows into this area of
reduced pressure. The velocity of the water from the nozzle pushes
it through the pipe toward the surface where the centrifugal pump
can lift it by suction. The centrifugal pump then forces it into the
distribution system. (See fig. 16.)
Selection of Pumping Equipment
The type of pump selected for a particular installation should be
determined on the basis of the following fundamental
considerations.
1. Yield of the well or water source.
2. Daily needs and instantaneous demand of the users.
3. The "usable water" in the pressure or storage tank.
4. Size and alinement of the well casing.
5. Total operating head pressure of the pump at normal
delivery rates, including lift and all friction losses.
6. Difference in elevation between ground level and water
level in the well during pumping.
7. Availability of power.
8. Ease of maintenance and availability of replacement parts.
9. First cost and economy of operation.
10. Reliability of pumping equipment.
The rate of water delivery required depends on the time of effective
pump operation as related to the total water consumption between
periods of pumping. Total water use can be determined from table 1, page
15. The period of pump operation depends upon the quantity of water on
hand to meet peak demands and the storage available. If the well yield
permits, a pump capable of meeting the peak demand (see table 9, page
124) should be used.
When the well yield is low in comparison to peak demand
requirements, an appropriate increase in the storage capacity is
required. The life of an electric drive motor will be reduced when
there is excessive starting and stopping. The water system,
therefore, should be designed so that the interval between starting
96
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Pressure
Switch
Regulating
Pressure Gage
^Discharge
FIGURE 16. "Over-the-well" jet pump installation.
97
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and stopping is as long as is practicable but not less than 1 minute.
Counting the number of fixtures in the home permits a ready
determination of required pump capacity from figure 17. For
example, a home with kitchen sink, water closet, bathtub, wash
basin, automatic clothes washer, laundry tub and two outside hose
bibs, has a total of eight fixtures. Referring to the figure, it is seen
that eight fixtures correspond to a recommended pump capacity
between 9 and 11 gallons per minute. The lower value should be the
minimum. The higher value might be preferred if additional fire
protection (see p. 17) is desired, or if garden irrigation (see "Lawn
Sprinkling," p. 16) or farm use (table 7) is contemplated.
(Note: This simple calculation does not take into account the
possibility that low well capacity may limit the size of pump that
should be installed. In this case, the system can be reinforced by
providing additional storage to help cover periods of peak demand.
See "Storage,"?. 124.)
The total operating head of a pump consists of the lift (vertical
distance from pumping level of the water source to the pump), the
friction losses in the pipe and fittings from water source to pump,
and the discharge pressure at the pump. (See fig. 18.)
Pumps that cannot be wholly submerged during pumping are
dependent on suction to raise the water from the source by
reducing the pressure in the pump column, or creating a suction.
The vertical distance from the source (pumping level) to the axis of
the pump is called the suction lift, and for practical purposes
cannot exceed between 15 and 25 feet, depending on the design of
the pump and the altitude above sea level where it is used.
Shallow well pumps should be installed with a foot valve at the
bottom of the suction line or with a check valve in the suction line
in order to maintain pump prime.
The selection of a pump for any specific installation should be
based on competent advice. Authorized factory representatives of
pump manufacturers are among those best qualified to provide this
service.
Sanitary Protection of Pumping Facilities
The pump equipment for either power-driven or manual systems
should be so constructed and installed as to prevent the entrance of
contamination or objectionable material either into the well or into
the water that is being pumped. The following factors should be
considered.
1. Designing the pump head or enclosure so as to prevent
pollution of the water by lubricants or other maintenance
materials used during operation of the equipment.
Pollution from hand contact, dust, rain, birds, flies,
rodents or animals, and similar sources should be
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102
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prevented from reaching the water chamber of the pump
or the source of supply.
2. Designing the pump base or enclosure so as to facilitate the
installation of a sanitary well seal within the well cover or
casing.
3. Installation of the pumping portion of the assembly near or
below the static water level in the well so that priming will
not be necessary.
4. Designing for frost protection, including pump drainage
within the well when necessary.
5. Overall design consideration so as to best facilitate necessary
maintenance and repair, including overhead clearance for
removing the drop pipe and other accessories.
When planning for sanitary protection of a pump, specific types
of installations must be considered. The following points should be
considered for the different types of installations.
Check Valves. The only check valve between the pump and
storage should be located within the well (see fig. 24, p. 114), or at
least upstream from any portion of a buried discharge line. This will
assure that the discharge line at any point where it is in contact
with soil or a potentially contaminated medium will remain under
positive system pressure — whether or not the pump is operating.
There should be no check valve at the inlet to the pressure tank or
elevated storage tank. This requirement would not apply to a
concentric piping system, with the external pipe constantly under
system pressure. (See fig. 14, p. 69; fig. 22, p. 112; and fig. 23, p.
113.)
Many pumps (submersibles, jets) normally have check valves
installed within the well.
Well Vents. A well vent is recommended on all wells not having a
packer-type jet pump. The vent prevents a partial vacuum inside the
well casing as the pump lowers the water level in the well. (The
packer-type jet installation cannot have a well vent, since the casing
is subjected to positive system pressure.) The well vent — whether
built into the sanitary well cover or conducted to a point remote
from the well — should be protected from mechanical damage, have
watertight connections, and be resistant to corrosion, vermin, and
rodents. (See fig. 7, p. 40; fig. 9, p. 47; and fig. 24, p. 114.)
The opening of the well vent should be located not less than 24
inches above the highest known flood level. It should be screened
with durable and corrosion-resistant materials (bronze or stainless
steel no. 24 mesh) or otherwise constructed so that openings
exclude insects and vermin.
Miscellaneous. Certain types of power pumps require that the
water be introduced into the pumping system, either to prime the
pump or to lubricate rubber bearings that have become dry while
103
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the pump was inoperative. Water used for priming or lubricating
should be free of contamination.
It is desirable to provide a water-sampling tap on the discharge
line from power pumps.
Installation of Pumping Equipment
Where and how the pump and power unit are mounted depend
primarily on the type of pump employed. The vertical turbine
centrifugal pump, with power source located directly over the well
and the pumping assembly submerged within the well, is gradually
being replaced by the submersible unit, where both the power unit
(electric motor) and the pump are submerged within the well.
Similarly, the jet pump is gradually giving way to the submersible
pump - especially for deeper installations - because of the latter's
inherently superior performance and better operating economy.
Vertical Turbine Pumps. In the vertical turbine pump
installation, the power unit (usually an electric motor) is installed
directly over the well casing. The pump portion is submerged within
the well, and the two are connected by a shaft enclosed within the
pump column. The pump column supports the bearing system for
the drive shaft and conducts the pumped water to the surface. (See
% 19.)
Since the long shaft must rotate at high speed (1,800 to 3,600
rpm), correct alinement of the motor, shaft, and pump is vital to
good performance and long life of the equipment. There are two
main points to consider in obtaining a proper installation:
1. Correct and stable positioning of the power unit.
2. Verticality and straightness of the pump column within the
well.
Since concrete slabs tend to deteriorate, settle, or crack from
weight and vibration, it is usually better to attach the discharge
head to the well casing. Figure 19 shows one way to accomplish
this. For smoothest operation and minimum wear, the plate (and
discharge head) should be mounted perpendicular to the axis of the
pump column as pump and column hang in the well. If the casing is
perfectly plumb, the pump column axis and the well axis coincide,
and a perfect installation results. It sometimes happens, though,
that the well is not plumb, or that it is crooked. In this case, it is
necessary to adjust the position of the plate so that the axis of the
pump column lies as close as possible to the axis of the well. If
there is enough room inside the casing (and this is one of the
reasons for installing larger casing), there is a better chance that
pump and column will be able to hang plumb -- or at least be able
to operate smoothly. Once the correct position of the plate is
determined, it is welded to the well casing. The discharge head is
then bolted securely to the support plate.
As explained under "Sanitary Construction of Wells" on p. 48,
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Bolt
Lock
Washer
1/2
Support
Plate
Pump
Discharge
Head
Line
Shaft
Weld, Inside
and Out
Well
Casing
'Adequate for 6"and smaller wells
FIGURE 19. Vertical (line shaft) turbine pump mounted on well casing.
105
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sanitary well seals or covers are available for installation to seal the
well casing against contamination entering at this point. Some
designs, however, make it difficult or impossible to measure water
levels within the well. This deficiency should be corrected by
welding to the side of the casing an access pipe, which permits
introduction of a water-level measuring device. A hole is first cut in
the casing at a point far enough below the top to permit clear access
past the discharge head of the pump. The angle between the access
pipe and the casing should be small enough to permit free entry of
the measuring line. Minimum inside diameter of the pipe should be
3/4 inch, and larger when possible. Before welding the pipe in place,
any sharp edges around the hole through the casing should be filed
smooth so that the measuring device will slide freely through
without catching or becoming scratched. An inclination angle of
one unit horizontal to four units vertical provides a good access —
or, in other words, for each foot down from the top of the casing,
the access pipe will be inclined outward 3 inches horizontally from
the top.
Some engineers and well service technicians recommend that all
wells be equipped with such access pipes because of the ease of
introducing and withdrawing measuring devices and because the
pipe permits chemical treatment of the well without removing the
sanitary well seal and pump.
The welding around the access pipe should be at least as thick
and resistant to corrosion as the well casing itself. This is especially
important if the connection will be located below the ground
surface.
Submersible Pumps. Because all moving parts of the submersible
pump are located within the well in a unit, this pump can perform
well in casings that might be too crooked for vertical turbine
pumps. If there is little difference between the inside casing
diameter and the outside diameter of the pump, the pump might
stick in the well casing, with the possibility that it could be damaged
during installation. If there is any doubt about whether there is
room, a "dummy" piece of pipe whose dimensions are slightly
greater than those of the pump should first be run through the
casing to make sure that the pump will pass freely to the desired
depth of setting.
The entire weight of the pump, cable, drop pipe, column of water
within the pipe, and reaction load when pumping must be
supported by the drop pipe itself. It is important, therefore, that
the drop pipe and couplings be of good quality steel, galvanized,
and of standard weight. (See "Casing and Pipe," p. 42.) Cast-iron
fittings should not be used where they must support pumps and
pump columns.
The entire load of submersible pumping equipment is normally
106
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suspended from the sanitary well seal or cover. An exception to this
would be the "pitless" installation. (See p. 109.)
Jet Pumps. Jet pumps may be installed directly over the well, or
alongside it. Since there are no moving parts in the well, straightness
and plumbness do not affect the jet pump's performance. The
weight of equipment in the well is relatively light, being mostly pipe
(often plastic), so that loads are supported easily by the sanitary
well seal. There are also a number of good "pitless adapter" and
"pitless unit" designs for both single and double pipe jet systems.
(Seep. 109.)
Hand Pumps. The pump heads on most force pumps are
designed with a stuffing box surrounding the pump rod. This design
provides reasonable protection against contamination. Ordinary lift
pumps with slotted pump head tops are open to contamination and
should not be used. The pump spout should be closed and directed
downward.
The pump base should be designed to serve a twofold purpose:
first, to provide a means of supporting the pump on the well cover
or casing top; and second, to protect the well opening or casing top
from the entrance of contaminated water or other harmful or
objectionable material. The base should be of the solid, one-piece,
recessed type, cast integrally with or threaded to the pump column
or stand. It should be of sufficient diameter and depth to permit a
6-inch well casing to extend at least 1 inch above the surface upon
which the pump base is to rest. The use of a flanged sleeve
embedded in the concrete well cover or a flange threaded or
clamped on the top of the casing to form a support for the pump
base is recommended. Suitable gaskets should be used to insure
tight closure.
The protective closing of the pump head, together with the
pollution hazard incident to pump priming, makes it essential that
the pump cylinders be so installed that priming will not be
necessary.
Pumphousing and Appurtenances
A pumphouse installed above the surface of the ground should be
used. (See fig. 20.) The pumproom floor should be of watertight
construction, preferably concrete, and should slope uniformly away
in all directions from the well casing or pipesleeve. It should be
unnecessary to use an underground discharge connection if an
insulated, heated pumphouse is provided. For individual
installations in rural areas, two 60-watt light bulbs, a
thermostatically controlled electric heater, or a heating cable will
generally provide adequate protection when the pumphouse is
properly insulated.
In areas where power failures may occur, an emergency,
107
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Removable
Roof/Walls
Shingles*
Sheathing
^SanitaryJ_\.™ __^_ .' Min4"T •_'. ^.
108
FIGURE 20. Pumphouse.
-------
gasoline-driven power supply or pump should be considered. A
natural disaster, such as a severe storm, hurricane, tornado, blizzard,
or flood, may cut off power for hours or even days. A gasoline,
power-driven electrical unit could supply the power requirements of
the pump, basic lighting, refrigeration, and other emergency needs.
Lightning Protection
Voltage and current surges produced in powerlines by nearby
lightning discharges constitute a serious threat to electric motors.
The high voltage can easily perforate and burn the insulation
between motor windings and motor frame. The submersible pump
motor is somewhat more vulnerable to this kind of damage because
it is submerged in ground water — the natural "ground" sought by
the lightning discharge. Actual failure of the motor may be
immediate, or it may be delayed for weeks or months.
There are simple lightning arresters available to protect motors
and appliances from "near miss" lightning strikes. (They are seldom
effective against direct hits.) The two types available are the valve
type and the expulsion type. The valve type should be preferred
because its "sparkover" voltage remains constant with repeated
operation.
Just as important as selecting a good arrester is installing it
properly. The device must be installed according to instructions
from the manufacturer and connected to a. good ground. In the case
of submersible pumps, this good ground can be achieved by
connecting the ground terminal of the arrester to the submersible
pump motor frame by means of a no. 12 stranded bare copper wire.
The low resistance (1 ohm or less) reduces the voltage surge
reaching the motor windings to levels that it can resist.
If steel well casing extends into the ground water, the ground can
be improved still further by also connecting the bare copper wire to
the well casing. IMPORTANT NOTE. Connecting the ground
terminal of the arrester to a copper rod driven into the ground does
not satisfy grounding requirements. Similarly, if a steel casing that
does not reach the ground water is relied upon, the arrester may be
rendered ineffective.)
Additional advice on the location and installation of lightning
arresters can be obtained from the power company serving the area.
Pitless Units and Adapters
Because of the pollution hazards involved, a well pit to house the
pumping equipment or to permit accessibility to the top of the well
is not recommended. Some States prohibit its use.
A commercial unit known as the "pitless adapter" is available to
eliminate well pit construction. A specially designed connection
between the underground horizontal discharge pipe and the vertical
casing pipe makes it possible to terminate the permanent,
109
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watertight casing of the well at a safe height (8 inches or more)
above the final grade level. The underground section of the
discharge pipe is permanently installed and it is not necessary to
disturb it when repairing the pump or cleaning the well. (See figs.
21-24.)
There are numerous makes and models of pitless adapters and
units available. Not all are of good design, and a few are not
acceptable to some States. The State or local health department
should be consulted first to learn what is acceptable.
Both the National Sanitation Foundation1 and the Water
Systems Council2 have adopted criteria intended to assure that
quality materials and workmanship are employed in the
manufacture and installation of these devices. Unfortunately, the
safety of these installations is highly dependent on the quality of
workmanship applied during their attachment in the field. For this
reason, additional precautions and suggestions are offered here.
There are two general types of pitless installations. One, the
"pitless adapter," requires cutting a hole in the side of the casing at
a predetermined depth below the ground surface (usually below the
frost line). Into this opening there is inserted and attached a fitting
to accommodate the discharge line from the pump. Its design varies
according to whether it is for a pressure line alone or for both
pressure and suction lines (two-pipe jet pump system with pump
mounted away from well). The other part of the adapter, mounted
inside the well, supports the pumping components that are
suspended in the well. Watertight connection is accomplished by a
system of rubber seals compressed by clamps or by the weight of
the equipment itself.
The second type — the "pitless unit" — requires cutting off the
well casing at the required depth and mounting thereon an entire
unit with all necessary attachments preassembled at the factory.
Regardless of the type of device employed, certain problems
arise, calling for special care. Some of these are described below,
with suggestions for their correction:
1. Welding below ground, in cramped quarters and under
all-weather conditions, is not conducive to good workmanship. If
welding must be done, the welder should be an expert pipe welder,
and he should have ample room for freedom of movement and ease
of visual inspection. A clamp-on, gasketed pitless adapter is easier to
install, but requires a smooth and clean surface for the gasket.
2. The pitless unit is manufactured and tested under factory
conditions. However, its attachment to the casing may present
special problems. If the well casing is threaded and coupled (T&C),
'National Sanitation Foundation, Post Office Box 1468, Ann Arbor, Mich. 48106.
2Water Systems Council, 221 North LaSalle St., Chicago, 111. 60601.
110
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Lift-Out Device
Snifter
Nfclve
Submersible
Pump Rower
Cable
FIGURE 21. Clamp-on pitless adapter for submersible pump installation.
Ill
-------
Lift-Out Device
Grout
Seal
FIGURE 22. Pitless unit with concentric external piping
for jet pump installation.
112
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Lift-out Device
Frost Line
Water-tight Weld on all Sides
0-Ring Seal
Space between Pipes Under
FIGURE 23. Weld-on pitless adapter with concentric external piping for
"shallow well" pump installation.
113
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-Sanitary Well Cover (Vented)
-Basement Wall
• Power
• Fused Disconnect Switch
or Circuit Breakers
Pump Controls
Pressure Tank
Pros
Outlet
FIGURE 24. Pitless adapter with submersible pump installation for
basement storage.
114
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it may be possible to adjust the height of one of the joints so that it
is about right for the attachment of the unit. If the height cannot
be adjusted, or if welded joints have been made, the casing must be
cut off at the proper depth below ground and then threaded.
Power-driven pipe-threading machines can be used to thread
casing "in place" in sizes up to and including 4 inches. Between 10
and 12 full threads should be cut on the casing to make a good,
strong joint. The threads should be good quality, cut with dies in
good condition.
When it is necessary to weld, the first requirement is that the
casing be cut off square. This cut can be made by special
casing-cutting tools working inside the casing, or by "burning" with
an acetylene torch from outside. If the torch method is used, it is
better to use a jig that attaches to the casing, supporting and
guiding the torch as the casing is burned off.
A competent welder should be able to make a strong weld if
given enough room in which to work. It is not so easy to get a
watertight joint under these conditions. Two or three "passes"
around the pipe should be made, following recommended
procedures for pressure pipe welding. The final welded connection
should be at least as thick, as strong, and as resistant to corrosion as
the well casing itself.
3. Clamps and gaskets are used for attachment of both adapters
and units. These devices have been criticized by some health
departments because of their relative structural weakness as
compared with other connections. It is feared by some that the
joint is more easily broken or caused to leak by mechanical damage,
or by frost-heave acting on the casing or the well slab.3
It is apparent that a watertight joint requires good contact
between the gasket and the surfaces against which it is to seal.
Corrosion-resistant, machined surfaces provide better conditions for
this seal. When the rubber gasket is required to seal against the
casing, special care must be taken to assure that the contact surface
is clean and smooth. Clamp-and-gasket connections should be
designed so that forces resulting from weight, misalinement,
twisting, settlement, and vibration are resisted by the metal parts,
and not by the rubber gaskets.
4. Materials used in adapters, adapter units, and accessories
should be selected carefully for strength and resistance of corrosion.
Corrosion potential is high in the earth formations found closest to
the surface and where there is moisture and air. To use metals of
differing "potential" in contact with each other in a corrosive
environment is to invite rapid destruction of one of them by
electrolytic corrosion. For example, steel clamps would be more
Some States prohibit the use of "Dresser type" connections for pitless units.
115
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compatible with steel casing than most other metals or alloys. Some
metals that by themselves resist corrosion — e.g., bronze, brass,
copper, aluminum — may corrode, or cause others to corrode, when
placed in contact with dissimilar metals. Different metals placed in
a corrosive environment should be insulated from each other by
rubber, plastic, or other nonconductor. Care should be taken in the
selection of welding materials; the welded connection is frequently
the point where corrosion begins.
Cast iron is more resistant to corrosion than steel under many
conditions of soil and water corrosiveness. However, some grades of
cast iron are unable to resist severe stresses resulting from tension,
bending, and impact. Metals used in castings subjected to such loads
should be selected, and the parts designed, to meet these
requirements. The consequences of breakage can be serious and
expensive, especially if pumping equipment, pipes, and accessories
fall into the well.
For the same reasons, plastics should be used in adapters and
units only where they are not subjected to severe forces of bending,
tension, or shear.
5. Extensive excavation around the well produces unstable soil
conditions, and later settlement is to be expected. Settlement of the
discharge line, unless at least a portion of the line is flexible, will
place a load on the adapter connection that could cause it to break
or leak. If for some reason the use of rigid pipe is necessary, the
connection should be by means of a "gooseneck," a "swing joint,"
or other device that will adjust to the settlement without
transferring the load to the adapter. The best fill material to use to
minimize settlement of the discharge line is fine to medium sand,
washed into place. With a correctly placed cement grout seal around
the casing and below the point of attachment (see fig. 25), the sand
will not find its way into the well. Sand does not shrink or crack in
drying, and several feet of it form an efficient barrier against
penetration by bacteria.
6. Once a pitless unit has been installed and tested, there remains
the risk of accidental damage to the buried connection. Numerous
cases of breakage by bulldozers and other vehicles have been
documented. Until all construction and grading around the area
have been completed, the well should be marked clearly with a post
and flag. A "2 x 4" 3 or 4 feet long, clamped or wired securely to
the well casing and bearing a red flag, has proved effective.
If the well is located in an area where motor vehicles are likely to
be operated, the final installation should include protective pipe
posts set in concrete. The posts should be just high enough to
protect the well, but not so high that they would interfere with well
servicing.
116
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Vacuum Gage
Hose Rtting
for Negative
Pressure Test
Pressure Gage
Snifter Valve for
Positive Pressure Test
Petcock Valve
Sanitary Well Seal
Air Line to
Test Plug
Safety Cham
Attached to
Test Plug
I 0 Aluminum
Pipe
Capped Discharge
Connection
I-IA" ^Aluminum
Pipe
Plumber's Test Plug
Inflated to Manufacturer
Recommended
Pressure
Reid Connection
FIGURE 25. Pitless adapter and unit testing equipment.
117
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Inspection and Testing of Pitless Devices
Pitless adapters and units are installed within the upper 10 feet of
the well structure — the zone of greatest potential for corrosion and
contamination. Procedures for inspecting and testing are therefore
important.
The buyer should select an adapter or unit that not only satisfies
health department requirements and the design criteria above, but
whose manufacturer will stand behind it.
Hiring a contractor with a reputation for good work is probably
the best assurance of getting the job done right. The owner should
insist that the contractor guarantee his work for at least 1 year.
Some State and local health departments maintain lists of licensed
or certified contractors authorized by law to construct wells and
install pumping systems.
Field connections on pitless adapters and units can be easily
tested with the equipment shown in figure 25. The lower plug is
first positioned just below the deepest joint to be tested, and then
inflated to the required pressure. The sanitary well seal is then
positioned in the top of the well and tightened securely to form an
airtight seal. This isolated section of the casing or unit is then
pressurized through the discharge fitting, or through a fitting in the
sanitary well seal. (See fig. 25.) A pressure of 5 to 7 pounds per
square inch should be applied and this pressure maintained, without
the addition of more air, for 1 hour. Warning: Do not hold face
over well seal while pressurized! While under pressure, all field
connections should be tested for leaks with soap foam. Any sign of
leakage — either by loss of pressure or by the appearance of bubbles
through the soap — calls for repair and retesting.
Adapters and units that depend on rubber or plastic seals in the
field connection should also be tested under negative pressure
conditions. This can be accomplished by connecting the hose fitting
(fig. 25) to a source of vacuum. The negative pressure is read on the
vacuum gage.
Positive pressure may be applied to the isolated section by means
of a tire pump, but a powered source makes the job much easier
and encourages better testing. If an air compressor is not available
or handy, a tire-inflation kit of the kind that uses automobile
engine compression will be found convenient. The plumber's test
plug should only be inflated by means of a hand-operated tire
pump.
Negative pressure is most readily applied by connecting a length
of vacuum hose (heavy wall, small bore) between the hose fitting in
the well seal and the vacuum system of an automobile engine. To
reach the desired negative pressure range (10 to 14 inches of
mercury vacuum), it may be necessary to accelerate the engine for a
period of time. Once the desired range is reached, the hose is
118
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clamped shut or plugged, the engine disconnected, and the vacuum
gage observed over a period of 1 hour to see whether there is any
detectable loss of negative pressure.
Leaks found in rubber or plastic seals should be closed by
tightening the clamps, if possible. In case a cement sealant must be
applied, it should be of a kind that will provide a strong yet flexible
bond between the sealing surfaces, and should be compounded to
provide long service when buried.
A negative pressure of 10 inches of mercury vacuum is equivalent
to about 11.3 feet of flood water over the joint in question when
the well casing is at atmospheric pressure.
DISTRIBUTION
Pipe and Fittings
For reasons of economy and ease of construction, distribution
lines for small water systems are ordinarily made up with standard
threaded, galvanized iron or steel pipe and fittings. Other types of
pipes used are cast iron, asbestos-cement, concrete, plastic, and
copper. Under certain conditions and in certain areas, it may be
necessary to use protective coatings, galvanizing, or have the pipes
dipped or wrapped. When corrosive water or soil is encountered,
copper, brass, wrought iron, plastic or cast iron pipe, although
usually more expensive initially, will have a longer, more useful life.
Cast iron is not usually available in sizes below 2 inches in diameter;
hence, its use is restricted to the larger transmission lines.
Plastic pipe for cold water piping is usually simple to install, has a
low initial cost, and has good hydraulic properties. When used in a
domestic water system, plastic pipe should be certified by an
acceptable testing laboratory (such as the National Sanitation
Foundation) as being nontoxic and non-taste-producing. It should
be protected against crushing and from attack by rodents.
Asbestos-cement pipe for water systems, available in the sizes
required, has the advantages of ease of installation and moderate
resistance to corrosion.
Fittings are usually available in the same sizes and materials as
piping, but valves are generally cast in bronze or other alloys. In
certain soils the use of dissimilar metals in fittings and pipe may
create electrolytic corrosion problems. The use of nonconductive
plastic inserts between pipe and fittings or the installation of
sacrificial anodes is helpful in minimizing such corrosion.
Pipes should be laid as straight as possible in trenches, with
air-relief valves or hydrants located at the high points on the line.
Failure to provide for the release of accumulated air in a pipeline on
hilly ground may greatly reduce the capacity of the line. It is
necessary that pipeline trenches be excavated deep enough to
prevent freezing in the winter. Pipes placed in trenches at a depth of
119
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more than 3 feet will help to keep the water in the pipeline cool
during the summer months.
Pipe Capacity and Head Loss
The pipeline selected should be adequate to deliver the required
peak flow of water without excessive loss of head; i.e., without
decreasing the discharge pressure below a desirable minimum. The
normal operating water pressure for household or domestic use
ranges from 20 to 60 pounds per square inch,4 or about 45 to 140
feet of head at the fixture.
The capacity of a pipeline is determined by its size, length, and
interior surface condition. Assuming that the length of the pipe is
fixed and its interior condition established by the type of material,
the usual problem in design of a pipeline is that of determining the
required diameter.
The correct pipe size can be selected with the aid of figure 26,
which gives size as a function of head loss, H, length of pipeline, L,
and peak discharge, Q. As an example of the use of figure 26,
suppose that a home and farm installation is served by a reservoir a
minimum distance of 500 feet from the point of use, one whose
surface elevation is at least 150 feet above the level of domestic
service, and in which a minimum service pressure of 30 pounds per
square inch is required. It will be necessary first to determine the
maximum operating head loss, i.e., the difference in total head and
the required pressure head at the service.
H=l 50-2.3X30=1 50-69=81 feet
The maximum peak demand which must be delivered by the
pipeline is determined to be 30 gallons per minute.
Q=30 gallons per minute
The hydraulic gradient is 0.162 foot per foot.
IT O1
-^=P777.=0.162 foot per foot
Entering figure 26, with the computed values of H/L and Q, one
finds that the required standard galvanized pipe size is
approximately 1-3/8 inches. Since pipes are available only in
standard dimensions, standard pipe of 1 ¥2 inches in diameter (the
next size) should be used.
Additional head losses may be expected from the inclusion of
4One pound per square inch is the pressure produced by a column of water 2.31 feet high.
120
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O.I
009
008
007
0.06
0.05
0.04
0.01
0.009
0.008
0.007
0006
0001
0.0009
0.0008
0.0007
0.0006
0.0005
00004
(Hazen- William Formula C-100)
0.0002
000015
3/4" I" 1-1/4" 1-1/2 2" 2-1/2" 3
Nominal Diameter- Standard Galvanized Pipe
FIGURE 26. Head loss versus pipe size.
121
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fittings in the pipeline. These losses may be expressed in terms of
the equivalent to the length and size of pipe which would produce
an equivalent loss if, instead of adding fittings, we added additional
pipe. Table 8 lists some common fitting losses in terms of an
equivalent pipe length.
TABLE 8. - Allowance in equivalent length of pipe for friction loss in valves
and threaded fittings
Diameter
of fitting
Inches
3/8
1/2
3/4
1
1-1/4
1-1/2
2
2-1/2
3
3-1/2
4
5
6
90° std.
ell
Feet
1
2
2.5
3
4
5
7
8
10
12
14
17
20
45° std.
ell
Feet
0.6
1.2
1.5
1.8
2.4
3
4
5
6
7
8
10
12
90° side
tee
Feet
1.5
3
4
5
6
7
10
12
15
18
21
25
30
Coupling
or straight
run
Feet
0.3
0.6
0.8
0.9
1.2
1.5
2
2.5
3
3.6
4
5
6
Gate
valve
Feet
0.2
0.4
0.5
0.6
0.8
1.0
1.3
1.6
2
2.4
2.7
3.3
4
Globe
valve
Feet
8
15
20
25
35
45
55
65
80
100
125
140
165
Angle
valve
Feet
4
8
12
15
18
22
28
34
40
50
55
70
80
In the example given above the inclusion of two gate valves
(open), two standard elbows, and two standard tees (through)
would produce a head loss equivalent to 15 feet of l^-inch pipe.
From figure 26 one finds that by using 515 feet of IVa-inch pipe
instead of the actual length of 500 feet (H/L=0.157), the capacity
of the system for the same total head loss is about 38 gallons per
minute, a satisfactory discharge.
It can be seen from this example that fitting losses are not
particularly important for fairly long pipelines, say greater than
about 300 feet. For pipelines less than 300 feet, fitting losses are
very important and have a direct bearing on pipe selected;
therefore, they should be calculated carefully.
Globe valves which do produce large head losses should be
avoided in main transmission lines for small water systems.
Interior piping, fittings, and accessories should conform to the
minimum requirements for plumbing of the National Plumbing
Code5 or equivalent applicable plumbing code of the locality.
Protection of Distribution Systems
The sanitary protection of new or repaired pipelines can be
facilitated by proper attention to certain details of construction. All
Obtainable at the American Society of Mechanical Engineeis, United Engineering
Center, 345 East 47th St., New York, N.Y. 10017.
122
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connections should be made under dry conditions, either in a dry
trench or, if it is not possible to completely dewater the trench,
above the ground surface. Soiled piping s°hould be thoroughly
cleaned and disinfected before connections are made. Flush valves
or cleanouts should be provided at low points where there is no
possibility of flooding.
When not properly designed or installed, frostproof hydrants may
permit contamination to enter the water system. Such hydrants
should be provided with suitable drainage to a free atmosphere
outlet where possible. The drainage from the base of the hydrant
should not be connected to a seepage pit which is subject to
pollution or to a sewer. The water-supply inlet to water tanks used
for stock, laundry tubs, and other similar installations should be
placed with an air gap (twice pipe diameter) above the flooding
level of the fixtures to prevent danger of back siphonage. There
should be no cross-connection, auxiliary intake, bypass, or other
piping arrangement whereby polluted water or water of
questionable quality can be discharged or drawn into the domestic
water supply system.
Before a distribution system is placed in service it should be
completely flushed and disinfected.
Disinfection of Water-Distribution System
General
These instructions cover the disinfection of water distribution
systems and attendant standpipes or tanks. It is always necessary to
disinfect a water system before placing it in use under the following
conditions:
1. Disinfection of a system that has been in service with raw or
polluted water, preparatory to transferring the service to
treated water.
2. Disinfection of a new system upon completion and
preparatory to placing in operation with treated water or
water of satisfactory quality.
3. Disinfection of a system after completion of maintenance
and repair operations.
Procedure
The entire system, including tank or standpipe, should be
thoroughly flushed with water to remove any sediment that may
have collected during operation with raw water. Following flushing,
the system should be filled with a disinfecting solution of calcium
hypochlorite and treated water. This solution is prepared by adding
1.2 pounds of high-test 70 percent calcium hypochlorite to each
1,000 gallons of water, or by adding 2 gallons of ordinary
household liquid bleach to each 1,000 gallons of water. A mixture
123
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of this kind provides a solution having not less than 100 mg/9. of
available chlorine.
The disinfectant should be retained in the system, tank, or
standpipe, if included, for not less than 24 hours, then examined
for residual chlorine and drained out. If no residual chlorine is
found present, the process should be repeated. The system is next
flushed with treated water and put into operation.
STORAGE
Determination of Storage Volume
Three types of storage facilities are commonly employed for
individual water supply systems. They are pressure tanks, elevated
storage tanks, and ground-level reservoirs and cisterns.
When ground water sources with sufficient capacity and not
requiring treatment are used, only a small artificial storage facility
may be needed since the water-bearing formation tapped
constitutes a natural storage area.
Pressure Tanks. Pressure in a distribution system served by a
pneumatic tank is maintained by pumping water directly to the
tank from the source. This pumping action compresses a volume of
entrapped air. The air pressure equal to the water pressure in the
tank can be controlled between desired limits by means of pressure
switches which stop the pump at the maximum setting and start it
at the minimum setting. The capacity of pressure tanks is usually
small when compared to the total daily water consumption. Tanks
are designed to meet only peak demands because only 10 to 40 percent of
tank volume is usable storage. The maximum steady demand the system
can deliver is equal to the pump capacity.
The usable storage of a pressure tank can be increased by "supercharg-
ing" with air at the time of installation, or by precharging at the factory.
Precharging can only be done in tanks having the water space and air
space completely separated by a diaphragm or bladder. Consult your
dealer for design details and characteristics.
The Water Systems Council6 recommends the figures in Tables 9 and
10 for the selection of pumps and pressure tanks for various size homes.
TABLE 9. Seven-minute Peak Demand Period Usage
Number of baths in home: 1 IVz 2-2 Yz 3-4
Normal 7-min. peak demand (gal.) 45 75 98 122
Minimum size pump to meet peak demand with-
out using storage 7 GPM 10 GPM 14 GPM 17 GPM
Note: Values given are average and do not include higher or lower extremes.
6Water Systems Council, 221 North LaSalle Street, Chicago, IL 60601.
124
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Using the pump capacity obtained from Table 9, find the tank size that
corresponds to the kind of tank (precharged, supercharged, or plain) and
the pressure range:
TABLE 10. Tank Selection Chart—Gallons (Based on present industry practice)
PUMP Minimum
CAPACITY Draw-
GPH
240
.100
360
420
480
540
600
660
720
780
840
900
960
1020
1080
1140
1200
GPM Down (Gals ) A«
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
4
5
6
7
8
9
10
12
13
15
17
19
20
23
25
27
30
15
15
20
20
25
30
30
35
40
45
55
60
65
70
80
85
95
20-40
B«
15
20
20
25
30
30
35
40
45
50
60
65
70
80
85
95
105
Switch Setting
Pounds Per Square Inch)
30-50
C*
20
30
35
40
40
50
55
60
70
80
90
100
110
120
135
150
160
A*
15
20
25
25
30
35
40
45
50
60
65
75
75
90
95
105
115
B*
20
25
25
30
35
40
45
50
60
65
75
80
90
100
110
120
130
40-60
C' A*
30
40
45
55
65
70
80
95
105
120
135
150
160
185
200
215
240
20
25
30
30
35
40
45
55
60
70
75
85
95
105
115
125
140
B'
20
25
30
40
45
50
55
65
70
80
90
105
115
125
140
150
165
C*
40
50
55
75
85
95
105
125
135
155
175
195
205
240
260
280
310
*A—Precharged bladder or diaphragm lank B—Supercharged, floating water tank C—Plain steel t
the minimum tank size needed.
When a pressure tank is provided in the distribution system there
is no difficulty with water hammer. Otherwise, it may be necessary
to provide an air chamber on the discharge line from the well
located near the pump to minimize the effects caused by water
hammer.
Elevated Storage. Elevated tanks should have a capacity which is
at least equal to 2 days' average consumption requirement. Larger
storage volume may be necessary to meet special demands such as
firefighting or equipment cleanup operations.
Ground-Level Reservoirs and Cisterns. Reservoirs that receive
surface runoff should generally be large enough to supply the
average daily demand over a drought period of maximum length.
Cisterns are customarily designed with sufficient capacity to
provide water during periods less than 1 year in duration.
Protection of Storage Facilities
Suitable storage facilities for relatively small systems may be
constructed of concrete, steel, brick, and sometimes of wood above
the land surface, or of concrete or brick if partially or wholly below
the ground surface. Such storage installations should receive the
same care as cistern installations in the selection of a suitable
location and provision against contamination. Asphalt or tar for
waterproofing the interior of storage units is not recommended
because of the objectionable taste imparted to the water and the
125
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possibility of undesirable chemical 'reaction with the materials used
for treatment. Specifications covering the painting of water tanks
are available from the American Water Works Association.7
Appropriate Federal, State, or local health agencies should be
consulted relative to approved paint coatings for interior tank use.
All storage tanks for domestic water supply should be completely
covered and so constructed as to prevent the possibility of pollution
of the tank contents by outside water or other foreign matter.
Figures 27 and 28 show some details for manhole covers and piping
connections to prevent the entrance of pollution from surface
drainage. Concrete and brick tanks should be made watertight by a
lining of rich cement mortar. Wood tanks are generally constructed
of redwood or cypress and while filled they will remain watertight.
All tanks require adequate screening of any openings to protect
against the entrance of small animals, mosquitoes, flies, and other
small insects.
Tanks containing water to be used for livestock should be
partially covered and so constructed that cattle will not enter the
tank. The area around the tank should be sloped to drain away
from the tank.
Figure 27 shows a typical concrete reservoir with screened inlet
and outlet pipes. This figure also illustrates the sanitary manhole
cover. The cover should overlap by at least 2 inches a rim elevated
at least 4 inches to prevent drainage from entering the reservoir.
This type of manhole frame and cover should be designed so that it
may be locked to prevent access by unauthorized persons.
The water in storage tanks, cisterns, or pipelines should not be
polluted with an emergency water supply that has been polluted at
its source or in transit.
Disinfection of storage facilities subsequent to construction or
repair should be carried out in accordance with the
recommendations stated under "Disinfection of Water Distribution
System" in this part of the manual.
7American Water Works Association, 2 Park Ave., New York, N.Y. 10016.
126
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Lock
Switch Control -
Screened Overflow
and Vent
FIGURE 27. Typical concrete reservoir.
127
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Overlapping, Circular Iron Cover
Iron Cover
Galvanized Sheet Metal
Over Wooden Cover
Concrete Cover
MANHOLE COVERS
Foot Piece or Brick
TYPICAL VALVE AND BOX
Pipe Connection With
Anchor Flange Casting
Coupling
Top of Cistern
or Reservoir
OVERFLOW AND VENT VENT
FIGURE 28. Typical valve and box, manhole covers, and piping installations.
128
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Bibliography
List of References on Individual Water
Supply S
ystems
American Public Health Association, American Water Works Association, and Water
Pollution Control Federation, Standard Methods for the Examination of Water and Waste
Water, 15th ed., Amer. Pub. Hlth. Assn., Washington, D.C. (1975).
American Water Works Association, Water Quality and Treatment, 3d ed., American Water
Works Association, New York, N.Y. (1971).
American Water Works Association, American Society of Civil Engineers, and Conference
of State Sanitary Engineers, Water Treatment Plant Design, American Water Works
Association, New York, N.Y. (1969)
American Water Works Association, Committee on Viruses in Water, "Viruses in Water,"
Journal of the American Water Works Association, Vol. 61, No. 10, pp. 491-494 (1969).
Anderson, Keith E., Water Well Handbook, Missouri Water Well and Pump Contractors
Association, Rolla. Mo. (1971).
Baker, R. J., Carroll, L. J., and Laubusch, E. J., Water Chlorination Handbook, American
Water Works Association, New York, N.Y. (19J2).
Capitol Controls Co., "Chlonnation Guide," Capitol Controls Co., Colmar, Pa. (undated).
Chang, S. L., "lodmation of Water," Boletin de la Oficina Sanitaria Panamericana, Vol. 59,
pp. 317-331 (1966).
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85-23), U.S. Government Printing Office, Washington, D.C. (Sept. 1965).
Gibson, U. P., and Singer, R. D.,- Water Well Manual, Premier Press, Berkeley, Calif.
(1971).
Goldstein, Melvin, McCabe, L. J., Jr., and Woodward, Richard L., "Continuous-Flow
Water Pasteurizer for Small Supplies," Journal of the American Water Works
Association, Vol. 52, No. 2. pp. 247-254 (Feb. 1960).
4
Hill, R. D., and Schwab, G. O., "Pressurized {Filters for Pond Water Treatment."
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Agricultural Engineers. St. Joseph, Mich. (1964).
129
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Hodgkinson, Carl, Removal of Coliform Bacteria from Sewage by Percolation through
Soil, University of California, Sanitary Engineering Research Laboratory, IER Series 90,
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Bulletin DPED-27, General Electric Co., Pittsfield, Mass. (1969).
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Water Data," Notes on Hydrologic Activities, Bulletin No. 12, U.S. Geological Survey,
Washington, D.C. (1966).
Joint Committee on Plastics. Thermoplastic Materials, Pipe, Fittings, Valves, Traps, and
Joining Materials (Standard No. 14), National Sanitation Foundation, Ann Arbor, Mich.
(1965).
National Association of Plumbing, Heating, and Cooling Contractors, National Standard
Plumbing Code, National Association of Plumbing, Heating, and Cooling Contractors,
Washington, D.C. (1971).
National Fire Protection Association, "Water Supply Systems for Rural Fire Protection,"
National Fire Codes, Vol. 8, Boston, Mass. (1969).
National Sanitation Foundation Testing Laboratory, Seal of Approval Listing of Plastic
Materials, Pipe, Fittings and Appurtenances for Potable Water and Waste Water, National
Sanitation Foundation, Ann Arbor, Mich, (revised annually).
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New York, N.Y. (1962).
Tardiff, R. D., and McCabe, L. J., "Rural Water Quality Problems and the Need for
Improvement," Second Water Quality Seminar Proceedings, pp. 34-36, American Society
of Agricultural Engineers, St. Joseph, Mich. (1968).
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Appendix A
Recommended Procedure for Cement
Grouting of Wells for Sanitary Protection1
The annular open space on the outside of the well casing is one of
the principal avenues through which undesirable water and
contamination may gain access to a well. The most satisfactory way
of eliminating this hazard is to fill the annular space with neat
cement grout. To accomplish this satisfactorily, careful attention
should be given to see that:
1. The grout mixture is properly prepared.
2. The grout material is placed in one continuous mass.
3. The grout material is placed upward from the bottom of the
space to be grouted.
Neat cement grout should be a mixture of cement and water in
the proportion of 1 bag of cement (94 pounds) and 5 to 6 gallons
of clean water. Whenever possible, the water content should be kept
near the lower limit given. Hydrated lime to the extent of 10
percent of the volume of cement may be added to make the grout
mix more fluid and thereby facilitate placement by the pumping
equipment. Mixing of cement or cement and hydrated lime with the
water must be thorough. Up to 5 percent by weight of bentonite
clay may be added to reduce shrinkage.
GROUTING PROCEDURE
The grout mixture must be placed in one continuous mass; hence,
before starting the operation, sufficient materials should be on hand
anfl other facilities available to accomplish its placement without
interruption.
Restricted passages will result in clogging and failure to complete
the grouting operation. The minimum clearance at any point,
including couplings, should not be less than IVi inches. When
grouting through the annular space, the grout pipe should not be
'This information has been taken principally from a pamphlet of the Wisconsin State
Board of Health entitled "Method of Cement Grouting for Sanitary Protection of Wells."
The subject is discussed in greater detail in that publication. (NOTE: Publication is out of
print.)
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less than 1-inch nominal diameter. As the grout moves upward, it
picks up much loose material such as results from caving.
Accordingly, it is desirable to waste a suitable quantity of the grout
which first emerges from the drill hole.
In grouting a well so that the material will move upward, there are
two general procedures that may be followed. The grout pipe may
be installed within the well casing or in the annular space between
the casing and drill hole if there is sufficient clearance to permit
this. In the latter case, the grout pipe is installed in the annular
space to within a few inches of the bottom. The grout is pumped
through this pipe, discharging into the annular space, and moving
upward around the casing, finally overflowing at the land surface.
In 3 to 7 days the grout will be set, and the well can be completed
and pumping started. A waiting period of only 24 to 36 hours is
required if quick-setting cement is used.
When the grout pipe is installed within the well casing, the casing
should be supported a few inches above the bottom during grouting
to permit grout to flow into the annular space. The well casing is
fitted at the bottom with an adapter threaded to receive the grout
pipe and a check valve to prevent return of grout inside of the
casing. After grout appears at the surface, the casing is lowered to
the bottom and the grout pipe is unscrewed immediately and raised
a few inches. A suitable quantity of water should then be pumped
through it, thereby flushing any remaining grout from it and the
casing. The grout pipe is then removed from the well and 3 to 7
days are allowed for setting of the grout. The well is then cleared by
drilling out the adapter, check valve, plug, and grout remaining
within the well.
A modification of this procedure is the use of the well casing
itself to convey the grout to the annular space. The casing is
suspended in the drill hole and held several feet off the bottom. A
spacer is inserted in the casing. The casing is then capped and
connection made from it to grout pump. The estimated quantity of
grout, including a suitable allowance for filling of crevices and other
voids, is then pumped into the casing. The spacer moves before the
grout, in turn forcing the water in the well ahead of it. Arriving at
the lower casing terminal, the spacer is forced to the bottom of the
drill hole, leaving sufficient clearance to permit flow of grout into
the annular space and upward through it.
After the desired amount of grout has been pumped into the
casing, the cap is removed and a second spacer is inserted in the
casing. The cap is then replaced and a measured volume of water
sufficient to fill all but a few feet of the casing is pumped into it.
Thus all but a small quantity of the grout is forced from the casing
into the annular space. From 3 to 7 days are allowed for setting of
the grout. The spacers and grout remaining in the casing and drill
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hole are then drilled out and the well completed.
If the annular space is to be grouted for only part of the total
depth of the well, the grouting can be carried out as directed above
when the well reaches the desired depth, and the well can then be
drilled deeper by lowering the tools inside of the first casing. In this
type of construction, where casings of various sizes telescope within
each other, a seal should be placed at the level where the
telescoping begins, that is, in the annular space between the two
casings. The annular space for grouting between two casings should
provide a clearance of at least 11/2 inches, and the depth of the seal
should be not less than 10 feet.
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Appendix B
Bacteriological Quality
SAMPLING
In the event that bacteriological samples must be obtained
without technical assistance, it is possible to insure satisfactory
results by following these steps carefully:
1. Use a sterile sample bottle provided by the laboratory that
will examine the sample.
2. Be very careful so that nothing except the water to be
analyzed will come in contact with the inside of the bottle
or the cap. Do not rinse the bottle.
3. Inspect the outside of the faucet. If water leaks around the
outside of the faucet, a different sampling point should be
selected.
4. Allow the water to run for sufficient time to permit clearing
of the service line before the sample of water is collected.
5. When filling the bottle, be sure that the bottle is held so that
no water which contacts the hands runs into the bottle.
6. Deliver the sample immediately to the laboratory. If samples
cannot be processed within 1 hour, the use of iced coolers
for storage of samples during transport is recommended.
In no case should the time elapsing between collection and
examination exceed 30 hours.
EXAMINATIONS
At the present time there are two methods used for determining
the bacteriological quality of a water supply: the multiple-tube
fermentation technique and the membrane filter technique.
The multiple-tube fermentation technique for determining the
presence of coliform bacteria requires 2 to 4 days to obtain results
after the sample is received in the laboratory. It also requires the
use of trained personnel and centralized laboratory facilities.
In addition, the membrane filter technique is a standard method
for making coliform determinations. This technique permits the
examination of a greater number of samples than the multiple-tube
test, with increased sensitivity in coliform detection. The most
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important benefit derived from the use of this technique is that
definite results are obtained in 18 to 20 hours, a much shorter time
than with the multiple-tube procedure. The membrane filter
method also permits field testing with self-contained portable kits
that are commercially available. The membrane filter technique
may be used in disasters and in emergencies such as those arising
from floods or hurricanes, where the time which elapses before
results of the examination are available is an important
consideration in the prompt initiation of protective measures.
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Appendix C
Emergency Disinfection
When ground water is not available and surface water must be
used, avoid sources containing floating material or water with a
dark color or an odor. The water tank from a surface source should
be taken from a point upstream from any inhabited area and
dipped, if possible, from below the surface.
When the home water supply system is interrupted by natural or
other forms of disaster, limited amounts of water may be obtained
by draining the hot water tank or melting ice cubes.
In case of a nuclear attack, surface water should not be used for
domestic purposes unless it is first found to be free from excessive
radioactive fallout. The usual emergency treatment procedures do
not remove such substances. Competent radiological monitoring
services as may be available in local areas should be relied upon for
this information.
There are two general methods by which small quantities of
water can be effectively disinfected. One method is by boiling. It is
the most positive method by which water can be made bacterially
safe to drink. Another method is chemical treatment. If applied
with care, certain chemicals will make most waters free of harmful
or pathogenic organisms.
When emergency disinfection is necessary, the physical condition
of the water must be considered. The degree of disinfection will be
reduced in water that is turbid. Turbid or colored water should be
filtered through clean cloths or allowed to settle, and the clean
water drawn off before disinfection. Water prepared for disinfection
should be stored only in clean, tightly covered, noncorrodible
containers.
METHODS OF EMERGENCY DISINFECTION
1. Boiling. Vigorous boiling for 1 full minute will kill any
disease-causing bacteria present in water. The flat taste of boiled
water can be improved by pouring it back and forth from one
container into another, by allowing it to stand for a few hours, or
by adding a small pinch of salt for each quart of water boiled.
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2. Chemical Treatment. When boiling is not practical, chemical
disinfection should be used. The two chemicals commonly used are
chlorine and iodine.
a. Chlorine
(1) Chlorine Bleach. Common household bleach contains a
chlorine compound that will disinfect water. The procedure to be
followed is usually written on the label. When the necessary
procedure is not given, one should find the percentage of available
chlorine on the label and use the information in the following
tabulation as a guide:
Available chlorine
1%
4-6%
7-10%
Drops per
quart of
clear water
10
2
1
1 If strength is unknown, add 10 drops per quart to
purify.
Double amount for turbid or colored water.
The treated water should be mixed thoroughly and allowed to
stand for 30 minutes. The water should have a slight chlorine odor;
if not, repeat the dosage and allow the water to stand for an
additional 15 minutes. If the treated water has too strong a chlorine
taste, it can be made more palatable by allowing the water to stand
exposed to the air for a few hours or by pouring it from one clean
container to another several times.
(2) Granular Calcium Hypochlorite. Add and dissolve one
heaping teaspoon of high-test granular calcium hypochlorite
(approximately 1/4 ounce) for each 2 gallons of water. This
mixture will produce a stock chlorine solution of approximately
500 mg/K, since the calcium hypochlorite has an available chlorine
equal to 70 percent of its weight. To disinfect water, add the
chlorine solution in the ratio of one part of chlorine solution to
each 100 parts of water to be treated. This is roughly equal to
adding 1 pint (16 oz.) of stock chlorine solution to each 12.5
gallons of water to be disinfected. To remove any objectionable
chlorine odor, aerate the water as described above.
(3) Chlorine Tablets. Chlorine tablets containing the
necessary dosage for drinking water disinfection can be purchased
in a commercially prepared form. These tablets are available from
drug and sporting goods stores and should be used as stated in the
instructions. When instructions are not available, use one tablet for
each quart of water to be purified.
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b. Iodine
(1) Tincture of Iodine. Common household iodine from the
medicine chest or first aid package may be used to disinfect water.
Add five drops of 2 percent United States Pharmacopeia (U.S.P.)
tincture of iodine to each quart of clear water. For turbid water add
10 drops and let the solution stand for at least 30 minutes.
(2) Iodine Tablets. Commercially prepared iodine tablets
containing the necessary dosage for drinking water disinfection can
be purchased at drug and sporting goods stores. They should be
used as stated in the instructions. When instructions are not
available, use one tablet for each quart of water to be purified.
Water to be used for drinking, cooking, making any prepared
drink, or brushing the teeth should be properly disinfected.
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Appendix D
Suggested Ordinance
The following is suggested for consideration in drafting an
ordinance for local application, subject to the approval of the
appropriate legal authority, to permit the exercise of appropriate
legal controls over nonpublic ground water supply systems used for
domestic purposes, to assure that the quality of such water is
protected by the proper construction and installation of wells,
pumping equipment and appurtenant pipelines.
This suggested legislation has been adapted from U.S. Public
Health Service Publication No. 1451, "Recommended State
Legislation and Regulations" (July 1965).
Persons using this draft as a guide are urged to familiarize
themselves with applicable legal requirements governing the
adoption of ordinances of this kind and to adapt the suggested
language as may be necessary to meet such requirements.
SUGGESTED LEGISLATION FOR WATER WELL
CONSTRUCTION AND PUMP INSTALLATION
[Title should conform to State requirements]
Be it enacted, etc.
Section 1. Short Title
This Act shall be known and may be cited as the "[State] Water
Well Construction and Pump Installation Act."
Section 2. Findings and Policy
The [State] legislature finds that" improperly constructed,
operated, maintained, or abandoned water wells and improperly
installed pumps and pumping equipment can affect the public
health adversely. Consistent with the duty to safeguard the public
health of this State, it is declared to be the policy of this State to
require that the location, construction, repair, and abandonment of
water wells, and the installation and repair of pumps and pumping
equipment conform to such reasonable requirements as may be
necessary to protect the public health.
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Section 3. Definitions
As used in this act:
(a) Abandoned water well means a well whose use has been
permanently discontinued. Any well shall be deemed abandoned
that is in such a state of disrepair that continued use for the
purpose of obtaining ground water is impracticable.
(b) Construction of water wells means all acts necessary to
obtain ground water by wells, including the location and excavation
of the well, but excluding the installation of pumps and pumping
equipment.
(c) Department means the [designated agency presently having
authority to regulate sanitary practices within the State, usually the
State department of health].
(d) Ground water means water occurring naturally in under-
ground formations that are saturated with water.
(e) Installation of pumps and pumping equipment means the
procedure employed in the placement and preparation for
operation of pumps and pumping equipment, including all
construction involved in making entrance to the well and
establishing seals, but not including repairs, as defined in this
section, to existing installations.
(f) Municipality means a city, town, borough, county, parish,
district, or other public body created by or pursuant to State law,
or any combination thereof acting cooperatively or jointly.
(g) Pumps and pumping equipment mean any equipment or
materials used or intended for use in withdrawing or obtaining
ground water, including, without limitation, seals and tanks,
together with fittings and controls.
(h) Pump installation contractor means any person, firm, or
corporation engaged in the business of installing or repairing pumps
and pumping equipment.
(i) Repair means any action that results in a breaking or
opening of the well seal or replacement of a pump.
(j) Well means any excavation that is drilled, cored, bored,
washed, driven, dug, jetted, or otherwise constructed when the
intended use of such excavation is for the location, extraction, or
artificial recharge of ground water; but such term does not include
an excavation made for the purpose of obtaining or for prospecting
tor oil, natural gas, minerals, or products of mining or quarrying, or
for inserting media to repressure oil or natural gas bearing for-
mation or for storing petroleum, natural gas, or other products.1
(k) Water well contractor means any person, firm, or corpora-
tion engaged in the business of constructing water wells.
'Some States may wish to include within the coverage of this definition seismological,
geophysical, prospecting, observation, or test wells.
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(1) Well seal means an approved arrangement or device used to
cap a well or to establish and maintain a junction between the
casing or curbing of a well and the piping or equipment installed
therein, the purpose or function of which is to prevent pollutants
from entering the well at the upper terminal.
Section 4. Scope
No person shall construct, repair, or abandon, or cause to be
constructed, repaired, or abandoned, any water well, nor shall any
person install, repair, or cause to be installed or repaired, any pump
or pumping equipment contrary to the provisions of this act and
applicable rules and regulations, provided that this act shall not
apply to any distribution of water beyond the point of discharge
from the storage or pressure tank, or beyond the point of discharge
from the pump if no tank is employed, nor to wells used or
intended to be used as a source of water supply for municipal water
supply systems, nor to any well, pump, or other equipment used
temporarily for dewatering purposes.
Section 5. Authority to Adopt Rules, Regulations, and Procedures
The Department shall adopt, and from time to time amend, rules
and regulations governing the location, construction, repair, and
abandonment of water wells, and the installation, and repair of
pumps and pumping equipment, and shall be responsible for the
administration of this act. With respect thereto it shall:
(a) Hold public hearings, upon not less than sixty (60) days'
prior notice published in one or more newspapers, as may be
necessary to assure general circulation throughout the State, in
connection with proposed rules and regulations and amendments
thereto.2
(b) Enforce the provisions of this act and any rules and
regulations adopted pursuant thereto.
(c) Delegate, at its discretion, to any municipality any of its
authority under this act in the administration of the rules and
regulations adopted hereunder.
(d) Establish procedures and forms for the submission, review,
approval, and rejection of applications, notifications, and reports
required under this act.
(e) Issue such additional regulations, and take such other
actions as may be necessary to carry out the provisions of this act.
This requirement should be consistent with the general practice for publication re-
quirements in the State and with any State administrative procedure act that may apply.
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Section 6. Prior Permission and Notification
(a) Prior permission shall be obtained from the Department for
each of the following:
(1) The construction of any water well
(2) The abandonment of any water well
(3) The first installation of any pump or pumping equip-
ment in any well
in any geographical area where the Department determines such
permission to be reasonably necessary to protect the public health,
taking into consideration other applicable State laws, provided that
in any area where undue hardship might arise by reason of such
requirement, prior permission will not be required.
(b) The Department shall be notified of any of the following
whenever prior permission is not required:
(1) The construction of any water well
(2) The abandonment of any water well
(3) The first installation of any pump or pumping equip-
ment in any well
(4) Any repair, as defined in this act, to any water well or
pump
Section 7. Existing Installations
No well or pump installation in existence on the effective date of
this act shall be required to conform to the provisions of subsection
(a) of section 6 of this act, or any rules or regulations adopted
pursuant thereto; provided, however, that any well now or hereafter
abandoned, including any well deemed to have been abandoned, as
defined in this act, shall be brought into compliance with the
requirements of this act and any applicable rules or regulations with
respect to abandonment of wells; and further provided, that any
well or pump installation supplying water that is determined by the
Department to be a health hazard must comply with the provisions
of this act and applicable rules and regulations within a reasonable
time after notification of such determination has been given.
Section 8. Inspections
(a) The Department is authorized to inspect any water well,
abandoned water well, or pump installation for any well. Duly
authorized representatives of the Department may at reasonable
times enter upon, and shall be given access to, any premises for the
purpose of such inspection.
(b) Upon the basis of such inspections, if the Department finds
applicable laws, rules, or regulations have not been complied with,
or that a health hazard exists, the Department shall disapprove the
well and/or pump installation. If disapproved, no well or pump
installation shall thereafter be used until brought into compliance
and any health hazard is eliminated.
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(c) Any person aggrieved by the disapproval of a well or pump
installation shall be afforded the opportunity of a hearing as
provided in section 13 of this act.
Section 9. Licenses
Every person who wishes to engage in such business as a water
well contractor or pump installation contractor, or both, shall
obtain from the Department a license to conduct such business.
(a) The Department may adopt, and from time to time amend,
rules and regulations governing applications for water well
contractor licenses or pump installation contractor licenses,
provided that the Department shall license, as a water well
contractor or pump installation contractor, any person properly
making application therefor, who is not less than twenty-one (21)
years of age, is of good moral character, has knowledge of rules and
regulations adopted under this act, and has had not less than two
(2) years' experience in the work for which he is applying for a
license; and provided further, that the Department shall prepare an
examination that each such applicant must pass in order to qualify
for such license.
(b) This section shall not apply to any person who performs
labor or services at the direction and under the personal supervision
of a licensed water well contractor or pump installation contractor.
(c) A county, municipality, or other political subdivision of the
State engaged in well drilling or pump installing shall be licensed
under this act, but shall be exempt from paying the license fees for
the drilling or installing done by regular employees of, and with
equipment owned by, the governmental entity.
(d) Any person who was engaged in the business of a water
well contractor or pump installation contractor, or both, for a
period of two (2) years immediately prior to (date of enactment)
shall, upon application made within twelve (12) months of (date of
enactment), accompanied by satisfactory proof that he was so
engaged, and accompanied by payment of the required fees, be
licensed as a water well contractor, pump installation contractor, or
both, as provided in subsection (a) of this section, without fulfilling
the requirement that he pass any examination prescribed pursuant
thereto.
(e) Any person whose application for a license to engage in
business as a water well contractor or pump installation contractor
has been denied, may request, and shall be granted, a hearing in the
county where such complainant has his place of business before an
appropriate official of [insert the name of the hearing body
designated in section 13 of this act].
(0 Licenses issued pursuant to this section are not transferable
and shall expire on of each year. A license may be renewed
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without examination for an ensuing year by making application not
later than thirty (30) days after the expiration date and paying the
applicable fee. Such application shall have the effect of extending
the validity of the current license until a new license is received or
the applicant is notified by the Department that it has refused to
renew his license. After of each year, a license will be renewed
only upon application and payment of the applicable fee plus a
penalty of $
(g) Whenever the Department determines that the holder of
any license issued pursuant to this section has violated any
provision of this act, or any rule or regulation adopted pursuant
thereto, the Department is authorized to suspend or revoke any
such license. Any order issued pursuant to this subsection shall be
served upon the license holder pursuant to the provisions of
subsection (a) of section 12 of this act. Any such order shall
become effective days after service thereof, unless a written
petition requesting hearing, under the procedure provided in section
13, is filed sooner. Any person aggrieved by any order issued after
such hearing may appeal therefrom in any court of competent
jurisdiction as provided by the laws of this State.
(h) No application for a license issued pursuant to this section
may be made within one (1) year after revocation thereof.
Section 10. Exemptions
(a) Where the Department finds that compliance with all
requirements of this act would result in undue hardship, an
exemption from any one or more such requirements may be
granted by the Department to the extent necessary to ameliorate
such undue hardship and to the extent such exemption can be
granted without impairing the intent and purpose of this act.
(b) Nothing in this act shall prevent a person who has not
obtained a license pursuant to section 9 of this act from
constructing a well or installing a pump on his own or leased
property intended for use only in a single family house that is his
permanent residence, or intended for use only for farming purposes
on his farm, and where the waters to be produced are not intended
for use by the public or in any residence other than his own. Such
person shall comply with all rules and regulations as to construction
of wells and installation of pumps and pumping equipment adopted
under this act.
Section 11. Fees
The following fees are required :
(a) A fee of $ shall accompany each application for
permission required under section 6(a) of this act.
(b) A fee of $ shall accompany each application for a
license required under section 9 of this act.
148
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Section 12. Enforcement
(a) Whenever the Department has reasonable grounds for
believing that there has been a violation of this act, or any rule or
regulation adopted pursuant thereto, the Department shall give
written notice to the person or persons alleged to be in violation.
Such notice shall identify the provision of this act, or regulation
issued hereunder, alleged to be violated and the facts alleged to
constitute such violation.
(b) Such notice shall be served in the manner required by law
for the service of process upon person in a civil action, and may be
accompanied by an order of the Department requiring described
remedial action, which, if taken within the time specified in such
order, will effect compliance with the requirements of this act and
regulations issued hereunder. Such order shall become final unless a
request for hearing as provided in section 13 of this act is made
within days from the date of service of such order. In lieu of
such order, the Department may require the person or persons
named in such notice to appear at a hearing, at a time and place
specified in the notice.
Section 13. Hearing
[Unless already prescribed in State law, this section should be
used to specify procedures for administrative hearing. ]
Section 14. Judicial Review
[Unless already prescribed in State law, this section should be
used to specify procedures for judicial review.]
Section 15. Penalties
Any person who violates any provision of this act, or regulations
issued hereunder, or order pursuant hereto, shall be subject to a
penalty of $ Every day, or any part thereof, in which such
violation occurs shall constitute a separate violation.
Section 16. Conflict With Other Laws
The provisions of any law, or regulation of any municipality
establishing standards affording greater protection to the public
health or safety, shall prevail within the jurisdiction of such
municipality over the provisions of this act and regulations adopted
hereunder.
Section 17. Severability
[Insert severability clause.]
Section 18. Effective Date
[Insert effective date.]
149
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Index
Abandoning wells 23, 54
ABS in water 7
Access pipe on well casing 106
Acidity 11, 88, 89
Activated carbon 70, 87
Adapters, pitless 109-119
Aeration 87, 91
Aggressive water 88, 89, 91
Air line 46
Air rotary drilling 41
Air tightness in wells (see also
Vent, well) 118
Algae 13, 20, 70, 87-89, 91
Alkalinity 11
Alkyl benzene sulfonate (ABS) 7
Analysis of water:
bacteriological ... 12,54,69,137,138
chemical 7, 23
radiological 6,13
Aquifer 1-4, 21-32
Arsenic 8
Artesian aquifers and
wells 22, 26-29, 53, 55
B
Bacteria:
coliform 12
in water 12, 22
Bacteriological analysis
of water 12, 54, 69, 137
Barium in water 8
Bentonite clay 133
Bleach for disinfection . 51, 78, 123, 140
"Blue baby" disease 10
Blue stone (blue vitriol) 87,89
Bored wells 30-33, 53
"Buried seals" 50
Cable tool drilling 39
Cadmium in water 8
Calcium hypochlorite . . 50, 78, 123, 140
Calcium in water 85
Calgon (polyphosphates) 89
Canals as source of water 71
Carbon, activated 70, 87
Carbon dioxide in water 91
Carbonate hardness 11
Casing for water wells (see also
Pitless adapters and units).... 19, 42, 43
Catchments 62
Cement grouting
of wells 48, 49, 54, 116, 133-135
Centrifugal pumps 94, 96
Ceramic filters 75
CH4 (methane) in water 55
Check valves 103
Chemical analysis of water 7, 23
Chemical characteristics:
of ground water 23
of water 7-11
Chemical disinfection
of water 67, 76-83, 139-141
Chlorides in water 8, 23
Chlorinated hydrocarbons
(see also Pesticides) 5, 10
Chlorination 67, 76-82, 87, 140
Chlorination equipment 80, 81
Chlorine:
demand 77
residual 77, 79, 90
Chromium 8
Churn drill (cable tool drill) 39
Cisterns 4, 62-66, 91, 125
COz (carbon dioxide) in water 91
Coagulation 74
Color in water 6, 27
Conditioning, water 83-91
Cone of depression 28
Cone of influence 28
Consolidated formations . 21, 22, 25, 41
Consumption, water 14-18
Contamination:
sources of 19, 20, 24, 25
threats to wells 25, 26, 48, 98,109,118
water supplies 11, 24-26
Copper in water 9, 87
Copper sulfate in algae control . .. 87, 89
Corrosion:
in pitless installations .. 115, 116, 118
of pipe lines 119
of well casing 42, 106, 115, 116
Corrosive water 7, 88, 89, 91
Covers:
sanitary well .19,46-49,98-103,106-107
spring box 56-58
Cyanide in water 8
151
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D
Dechlorination 82
Demand, water, for various uses . . 14-18
Destroying (abandoning) wells 54
Detergents in drinking water 7
Development of wells 44
Diatomaceous earth filters 75
Diatoms in water 89
Disinfection:
of springs 58
of water 67, 76-83, 139-141
of water-distribution systems .... 123
of wells 50-52
Distances, "safe," between water source
and source of contamination.. 19, 24, 25
Distribution system 119-124
Distribution system, disinfection of .123
Down-the-hole air hammer 42
Drawdown 28
Drilled wells 30, 39-44, 53
Drilling equipment and methods . . 28-45
Drinking Water Standards USPHS . . 8, 54
Drive (well) points 35-39
Driven wells 31, 35-39, 53
Dug wells 30-33, 51, 55
Dynamic (total operating) head 98
E
Efficiency, pump 100, 101
Epsom salts in water 10, 23
Equipment, chlorination 80, 81
Equipment, pumping 93-119
housing of 107-109
installation of 49, 104-107
selection of 96-98
Farm livestock water needs 15, 90
Fast-setting cement 133
Federal Radiation Council 13
Fertilizers, mineral, in water 13
Filters for water treatment 62, 67, 74-76
Filtration, natural 22, 25, 73
Fire protection 17, 125
Fish tolerance to copper 90
"Flame safety lamp" 55
Flooding of wells 19, 49, 123
Flowing artesian wells 27, 53
Fluoridation of water 86, 87
Fluorides in water 8, 9, 86, 87
Foaming in water 7
Formation seal 19, 48, 49, 116
Formations:
consolidated 22, 25, 41
unconsolidated 22, 24, 41
Freezing protection for:
wells 49, 107
discharge lines 107, 119
pumping equipment .... 70, 103, 107
Friction (head loss, energy loss)
in pipes and fittings 120-122
G
Gas in well water 55
Geological survey 18-20, 25
Geological Survey, U.S 7, 22, 24
Geology and
ground water. . 19, 21, 22, 24, 25, 30-32
Glauber's salt 10, 23
Greensand 85
Ground water:
basins 22
movement 3, 4
quality 5, 22-24
temperature 23
Grouting, cement,
of wells 19, 48, 49, 116, 133
H
Hand pumps 107
Hardness:
in ground water 23
in water 11, 85
treatment for 85, 86
Head:
dynamic 120
operating, of pumps 98
pressure 98, 120
Head loss 98, 120-122
Herbicides 70, 71
High-test calcium
hypochlorite(HTH) . .. 50, 78, 123, 140
Home water needs 14-18
HaS (hydrogen sulfide) in
well water 55, 91
I
Infiltration galleries 59
Inspection:
of pitless installations 118
of proposed well sites (sanitary
and geological surveys) . 18-20, 24, 25
of wells 49, 50, 118
Interference between wells 28, 29
Iodine for disinfection of water . 83, 141
Ion exchange 85
Iron bacteria 84
Iron in water 9, 23, 27, 83, 87, 91
Irrigation canals as source of water ... 71
J
Jet pumps 49, 93, 96, 107
152
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Jetted wells 32, 39
Jetting, development of wells by 44
L
Lakes, as source of water 66
Lawn sprinkling, water required for . . 16
LAS in water 7
Lead in water 8
Lead packer (seal) 44
Legislation, suggested, for water well
construction and pump
installation 143-149
Light, effect on algae growth .... 13, 89
Lightning, protection of pumps
against 109
Lime-soda ash process for
softening 85, 86
Lubrication of pumps 94, 98
M
Magnesium in water 23, 85
Manganese in water 9, 23, 83, 91
Membrane filter (MF) 12
Methane gas in water 55
Methemoglobinemia 10
Minerals in
water 5, 7-11, 83-86, 88, 89, 91
Mining, pollution from 10
Most probable number (MPN) 12, 20
Mud rotary drilling 39-41
N
National Fire Protection
Association 17, 18
National Water Well Association 22
Nitrates in water 10, 23
Nonartesian wells 26
Noncarbonate hardness 11
0
Odors in water 6, 23, 70, 87, 91
OTA (orthotolidine) 79
Ozone in water disinfection 83
Painting water storage tanks 126
Percussion (cable tool) drilling 39
Permanent hardness 11
Permeability, effect on wells 28
pH 11, 77
Pesticides in water 5, 10
PHS Drinking Water Standards 8, 54
Piezometric surface 37
Pipe:
and fittings, friction loss in . 120-122
for distribution systems 119
for well casing 42, 43
plastic 119
Pitless adapters and units 47, 48, 109-119
Pitless installations, testing .... 118, 119
Pit, well 109
Pneumatic pressure systems 18, 124
Pollution, sources of 19, 20, 24-26
Polyphosphates 89
Ponds and lakes 66
Positive displacement pumps 93
Pressure filters 75
Pressure, operating 120
Pressure tanks 124
Priming of pumps 103, 107
Protecting pumps against lightning . .. 109
Protection, sanitary:
of springs 58
of wells . . 22, 24-26, 48, 98, 109, 118
Pump:
alinement in wells 104, 106
lubrication 94, 98
platforms 49
priming 103, 107
Pumphouses 19, 107-109
Pumping:
equipment, selection of 96-98
facilities, sanitary protection of ... 98
Pumps:
centrifugal 94-96
hand 107
helical or spiral rotor 93
installation of 49, 104
jet 49, 93, 96, 107
line-shaft (vertical) turbine 104
positive displacement 93
shallow well 98
submersible 94, 95, 106
vertical turbine 93, 94
Quality:
of ground water 22, 23
of surface water 4-14, 18, 20, 61
Quantity of water needed for
various uses 14-18
Quick-setting cement 133
R
Radiation Protection Guides 13
Radioactivity in water 6, 13
Radiological factors 6, 13
Radius of influence 28
Rates of flow for various fixtures . 16, 17
Reciprocating pumps 93
Reconstruction of dug wells 55
"Red water" (see Iron in water)
Repair of wells 49, 116
Rights, water 1
153
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Rock formations, classification of .... 21
Rotary drilling methods 39-42
Rust (iron) in water 9, 23, 83, 91
S
"Safe" distances between water source
and contamination sources . . 19, 24-26
Salt in water (see Sodium; Chlorides)
Sand in well water 38, 42-45
Sand (well) points 35-38
Sanitary covers:
for spring boxes, cisterns . . 58, 64, 65
for wells 19, 46-49, 106, 107
Sanitary protection:
of distribution systems . 103, 122, 123
of springs 56, 58
of storage 64, 66, 125
of wells 24-26, 98, 109, 118
Sanitary quality of ground water 22
Sanitary survey 18-20
Screens, well 19, 30, 35-38, 42-44
installation of 42
selection of 38, 42-44
Seal, cement grout
(formation) 19, 48, 49, 116
Seal (cover), sanitary well
19, 46-49, 98-103, 106, 107
Sedimentation in water treatment . 67, 74
Selenium in water 8
Servicing wells 48, 103, 116
Settling basins 67
Silver in water 8, 83
Site selection for wells 19, 20, 24-26
Slab, well 49, 104, 107
Slow sand filters 75
Sodium arsenite, use in testing for
residual chlorine 79
Sodium hypochlorite 50, 78, 140
Sodium in water 10, 23, 85
Softening of water 85, 86, 87
Sources of water 1
Specific capacity of wells 30
Springs 4, 27, 56-58
Staining of clothing and fixtures . . 83, 84
Standards, USPHS Drinking Water . . 8, 54
Static water level 28
Steel pipe for casing 42, 43
Storage of water
14,17,18, 66, 67, 91,124-128
Storage tanks, painting of 126
Stream as source of water 71
Sulfates in water 10, 23
Sulfur (hydrogen sulfide)
in water 55, 91
Superchlorination 82
Surface water supplies 4, 20, 61-71
Survey, geological 24, 25
Survey, U.S. Geological 7, 22, 24
T
Taste and odor in water . . .6, 23, 70, 87, 91
Temporary hardness 11
Temperature:
of ground water 23
of water 7
Testing:
pitless adapters and units
for leaks 118,119
water for bacteria .... 11, 54, 69, 137
water for minerals 7, 23
wells for capacity 45
Tincture of iodine 141
Toxic substances in water 8
Treatment of water 73
Turbidity in water 6, 20,70, 141
U
Ultraviolet light for disinfection
of water 82
Unconsolidated formations .... 22, 25, 41
U.S. Geological Survey 7, 22, 24
V
Valves:
air relief 119
check 103
Vent, well 19, 103
Vertical turbine pumps 104
W
Water conditioning 83-91
Water consumption (demand) 14-18
Water disinfection 67, 76-83, 139-141
with chemicals .... 67, 76-83, 139-141
with ultraviolet light 82
Water quality 5-14
Water rights 1
Water table (nonartesian) wells 26, 28
Water treatment 73-91
Water use 14-18
Weed control 70
Well:
abandonment (destruction) .... 23, 54
casing 19, 42, 43
construction .. 19,28-44,55,109-119
covers 19, 48, 98-103,106,107
development (see also Well construction;
Site selection for wells) 44
disinfection 50-54
failure 46
grouting 19, 49, 54, 116,133-135
inspection 18, 20, 49, 50, 118
154
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log .......................... 19 for leaks .................... 118
pits ........................ 109
points ..................... 35-38 Y
repair .................... 49, 116 Y- ij.
screens ............ 19, 30, 35-38, 42 1C '
seals ........... 19,48,49,106,107
slabs ............. ... lOMO? ................ 45
straightness .............. 104, 106
yield .............. ;> ...... 28, 45 Z
Well testing: Zeolite softening .................. 85
for capacity ................... 45 Zinc in water .................... 10
155
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ENVIRONMENTAL PROTECTION AGENCY
REGIONAL WATER SUPPLY AGENCIES
REGION I—Connecticut, Maine,
Massachusetts, New Hampshire,
Rhode Island, Vermont
John F. Kennedy Federal Building
Boston, Mass. 02203
Tel. (617) 223-5731
REGION II—New Jersey, New York,
Puerto Rico, Virgin Islands
Federal Building
26 Federal Plaza
New York, N.Y. 10007
Tel. (212) 264-1800
REGION III—Delaware, District of
Columbia, Maryland, Pennsylva-
nia, Virginia, West Virginia
Curtis Bldg., 6th & Walnut Streets
Philadelphia, Pa. 19106
Tel. (215) 597-8227
REGION IV—Alabama, Florida,
Georgia, Kentucky, Mississippi,
North Carolina, South Carolina,
Tennessee
345 Courtland Street
Atlanta, Ga. 30308
Tel. (404) 881-3781
REGION V—Illinois, Indiana,
Michigan, Minnesota, Ohio,
Wisconsin
230 South Dearborn Street
Chicago, 111. 60604
Tel. (312) 353-2151
REGION VI—Arkansas, Louisiana,
New Mexico, Oklahoma, Texas
1201 Elm Street
Dallas, Tex. 75270
Tel. (214)749-2106
REGION VII—Iowa, Kansas, Missouri,
Nebraska
324 E. llth Street
Kansas City, Mo. 64106
Tel. (816) 374-5429
REGION VIII—Colorado, Montana,
North Dakota, South Dakota, Utah,
Wyoming
Lincoln Tower Building
1860 Lincoln Street
Denver, Colo. 80295
Tel. (303) 837-2731
REGION IX—Arizona, California, Ha-
waii, Nevada, Guam, American Sa-
moa, Trust Territory of Pacific
Islands
215 Fremont Street
San Francisco, Calif. 94105
Tel. (415)974-8106'
REGION X—Alaska, Idaho, Oregon,
Washington
1200 Sixth Avenue
Seattle, Wash. 98101
Tel. (206) 442-1223
i, V. S. GOVERNMENT PRINTING OFFICE • 1982 389-245;
-------
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
Regional Office*
Boston, Massachusetts 02203
New York, New York 10007
Philadelphia, Pa. 19106
Atlanta, Georgia 30308
Chicago, Illinois 60604
Dallas, Texas 75270
Kansas City, Missouri 64106
Denver, Colorado 80295
San Francisco, Calif. 94105
Phone States Covered
617-223-7210 Connecticut, Maine, Massachusetts,
New Hampshire, Rhode Island,
Vermont
212-264-2525 New Jersey, New York, Puerto Rico,
Virgin Islands
215-597-9814 Delaware, Maryland, Pennsylvania,
Virginia, West Virginia, D.C.
404-881-4727 Alabama, Florida, Georgia, Kentucky,
Mississippi, North Carolina,
South Carolina, Tennessee
312-353-2000 Illinois, Indiana, Michigan,
Minnesota, Ohio, Wisconsin
214-767-2600 Arkansas, Louisiana, New Mexico,
Oklahoma, Texas
816-374-5493 Iowa, Kansas, Missouri, Nebraska
303-837-3895 Colorado, Montana, North Dakota,
South Dakota, Utah, Wyoming
415-974-8153 Arizona, California, Hawaii, Nevada,
American Samoa, Guam, Trust
Territories of Pacific Islands, Wake
Island
Seattle, Washington 98101
206-442-1220
Alaska, Idaho, Oregon, Washington
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