Public water-supplies : requirements, resources, and the construction of works

Front matter

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Preface To The Second Edition

Since the publication of the first edition of this work, in 1901, there has been a noteworthy development in the design and construction of works for public water-supplies. While this development has been greatest in the methods of water purification and in the construction of purification works for the large cities of the country, yet it may be said that the engineering of water-works has in general been brought to a more scientific as well as economical basis. In the revision of this work the authors have endeavored to bring it into accordance with the best modem practice.

The chapters relating to the purification of water have been thoroughly revised, that on mechanical or rapid filtration being rewritten and greatly enlarged. In view of the essential diflferences between the two systems of filtration and the direction along which their development is taking place the authors decided to change the term "mechanical filtration," formerly used, to "rapid sand filtration," and to employ the term " slow sand filtration" for the other system. The subject of coagulation is now made an important part of the chapter on Sedimentation and Coagulation. Besides the matter relating to purification many other changes and additions have been made in nearly every chapter. The most important of these relate to methods of bacterial examination of water, the investigation of gmund-water and the construction of collecting works, data on the use of water, data on rainfall and flow of streams, the construction of dams, and the application of reinforced concrete to conduits, dams, filters, reservoirs, and tanks. The literature of each chapter has also been extended and brought up to date.

F. E. T.

H. L. R.

Madison, Wis., July, 1908.

fit

Preface To The First Edition

Tbe present volume has been prepared with particular reference to the needs of teachers and students in technical schools in which the subject of Water-supply receives a considerable amount of attention. The work is based chiefly upon the experience of the first-named author in teaching the subject for a number of years in the institution with which he is connected, and has been written with special reference to use in his own class-room.

In the discussion of the various subjects treated, the endeavor has been to lay stress upon fundamental principles rather than upon details of practice, although methods of construction have been freely given where they might serve to illustrate the principles involved or bring out the effects of differences in conditions. With the same idea in mind many problems, usually treated empirically, have been subjected to analysis, more or less crude, but useful for calling attention to certain general laws and limitations. It is believed also that such analyses may often be of much assistance in utilizing the results of observation, and that, if properly applied, they will aid much in the cultivation of the judgment. The necessity for the designer to keep constantly before him the question of true economy has been frequently emphasized, and to aid the beginner a brief general discussion of this subject has been given in Chapter XI. No apology is necessary at this time for the comparatively full treatment given to the subject of the Quality of Water-supplies in Chapters VIII, IX, and X. The authors have felt that the great importance of questions relating to the purification of water requires a more thorough presentation of the sanitary phase of the subject than has heretofore been customary in works designed for engineers. The subject of Ground-water has also received considerably more attention than is usual, but, it is thought, not more than the importance of the subject will justify.

References to authorities are numerous, and the plan has been adopted of giving, at the end of each chapter, a brief list of the best literature of the subject treated. It is believed that this feature will prove of value not only to the student, but esj)ecially to the young practitioner who finds it necessary to make a special study of a particular branch of the

VI PREFACE TO THE FIRST EDITION.

subject. According to the authors' view, there is no branch of the profession in which a good working library, consisting largely of periodicak, is more necessary than in that of municipal or sanitary engineering.

To the water-works specialist there is doubtless little that is new to be found in this work, but it is hoped that the form in which a large amount of widely scattered information has here been presented will prove of convenience to this class of readers.

With regard to the authorship it is proper to say that Chapters VIII, IX, and X are by Prof. Russell; also several of the articles of Chapters XIX to XXin, which relate more specifically to bacteriological and chemical features. The remainder of the work, with the exception of the chapter on Pumping-machinery, has been written by Prof. Tumeaure.

The authors desire to acknowledge their indebtedness to the various engineers and water-works officiak who have kindly responded to requests for information. They are also under special obligations to Mr. C. B. Stewart, Assoc. M. Am. Soc. C. E., for a very thorough investigation of the literature of the flow of water in pipes, the results of which appear on pages 227-234, including the diagram of Fig. 34. Of the large number of original articles and pap)ers which have been consulted, a great many have appeared in the Engineering News^ the Engineering Record^ or the Transactions of the American Society of Civil Engineers; and to the publishers of these journals special thanks are due for many of the illustrations which appear in this work.

ILL.R.

Madison, Wis., March, 1901

Introduction

PAGE

Historical Sketch. — Water-supplies in Ancient Times — Water-works of the Romans — The Middle Ages — Development of Modern Water-works in Europe — Development of Water-works in the United States i

Value and Iiiportance of a Public Water-supply. — Domestic Use — Commercial

Uses — Public Uses — Literature 12

Part I. Requirements And Resources

A. QUANTITY OF WATER REQUIRED: SOURCES OF SUPPLY.

CHAPTER IL

quantity op water required.

Nature of the Problem — Consumption, How Stated — Influences Affecting the Consumption per capita — Consumption of Water for Various Purposes — Total Consumption per capita — Increase in Consumption — Variations in Consumption — Consumption in European Cities — Growth of Cities — Literature 15

Chapter III

sources op supply.

Classification — Quality of Water from Various Sources — Utilization of the Various

Sources 38

Chapter IV. The Rainfall

Measurement of Rainfall — Rainfall Statistics — Mean Annual Rainfall — Secular Variations in the Rainfall — Mean Monthly Rainfall — Minimum Yearly Rainfall — Majdmum Rates of Rainfall — Extent of Great Rain-storms — Literature 41

Chapter V. Evaporation And Percolation

Relation of Evaporation and Percolation tp Stream-flow and to Ground-water. 54

Evaporation prom Water-surfaces. — Influences Affecting Evaporation — Experiments on Evaporation from Water-surfaces — Calculated Evaporations from Water-surfaces 55

vii

Vlll CONTENTS.

PACK

Percolation and Evaporation from Land-surfaces. — Influences Affecting Evaporation and Percolation — Effect of Vegetation or Other Soil -covering — Experiments on Evaporation and Percolation — Evaporation as Determined from Stream-flow — Amount of Percolation over Large Areas — Literature 57

Chapter VI. Flow Of Streams

General Methods of Procedure — Influences Affecting Stream-flow — Units of Measure

— Division of the Subject 66

Minimum Flow 68

Maximum or Flood Flow. — General Considerations — Data of Maximum Rates of

Flow — Formulas for Flood-flow — Rational Method of Estimating Flood-flow —

Diagram of Flood-flows — Example — Some Great Floods 69

Total Flow for Various Periods of Time. — Statistics of Stream-flow — Minimum Yearly Flow — Monthly and Seasonal Flow — Estimates of Flow — Effect of Lakes and Ponds on Stream -flow — Example of Estimate of Flow — Literature 78

CHAPTER VIL

GROUND- WATER.

General Considerations. — Occurrence of Ground-water — General Form of the Water-table — Porosity of Soils — Formations Favorable for the Transmission of Ground-water — Occurrence of Water-bearing Formations 89

Flow op Ground-water. — Methods of Determining the Flow of Ground-water — Formula for Estimating Velocity of Flow — Direct Method of Determining Velocity

— Quantity Flowing — Quantity Available 94

Springs. — Formations of Springs — Yield of Springs 102

Artesian Water. — General Conditions — Use of the Word *' Artesian " — The Character and Inclination of the Strata — Capacity — Predictions Concerning Artesian Wells — Important Artesian Areas in the United States — Literature 106

B. QUALITY OF WATERrSUPPLIES.

CHAPTER VIII. examination op water-supplies.

Scope and Extent of Examination — Necessity of Full Data in Interpreting Conditions — Collection of Samples — Sanitary Analysis of Water — Detection of Pollution by Addition of Chemicals — Various Analytical Methods — Value of Different Methods. 1 1 5

Physical Examination of Water. — Color — Turbidity — Odor and Taste — Temperature — Chemical Reaction 122

Chemical Examination of Water. — Purpose of Chemical Tests — Expression of Chemical Data — Interpretation of Chemical Data — Total Solids and Character of Same — Loss on Ignition — Chlorine — Organic Matter — Free and Albuminoid Ammonia — Oxygen Consumption — Nitrites — Nitrates — Summary. 125

Bacterial Examination of Water. — Development of Methods — Scope of Bacterial Tests — Methods of Determining Bacteria — Multiplication of Bacteria in Collected Sample — Quantitative Bacterial Analysis — Qualitative Bacterial Analysis — Presumptive Tests — Litmus-Lactose Agar Test — Fermentation Tests — Number

CONTENTS. ix

of Spedes — Significance of Liquefying Bacteria — Significance of Colon Badllus — Other Sewage Types — Isolation of Sewage Types — Animal Tests — Concentra- • tion of Oiganisms in Water — Detection of Specific Disease-bacteria — Isolation of Typhoid Organism — Isolation of Cholera — Disinfection of Polluted Wells and Pipes — Bacterial Control of Filter Operations 131

Microscopical Exaionatign of Water. — Scope of Microscopic Examinations — Direct Microscopic Examination in Filtration-work 143

Sanitary Surveys. — Object and Value — Literature 144

CHAPTER IX.

QUALITY OF WATER.

Importance of Quality — Changes in Quality Determined by Course of Water — Requirements as to Quality — Potableness — Water for Domestic Use — Water for Manufacturing Purposes — Distribution of Bacteria in Soil 149

Meteoric Waters. — Absorption of Impurities from Air. 153

Surface-waters. — Character Determined by Nature of Underlying Soil — Surface-waters as Potable Supplies — Physical Appearance — Bacterial Condition of Flowing Streams — Self-purification of Streams — Causes of Self-purification of Streams

— Dilution — Sedimentation — Vital Concurrence — Unsuitable Food-supply — Aeration — Chemical Reaction — Conclusion — Vertical Circulation in Lakes — Bacterial Content of Open Surface-waters — Natural Purification Processes — Influence of Vegetation — Odors in Water-supplies — Influence of Freezing on Bacterial Life 154

Subterranean Waters. — Change in Quality Due to Percolation — Purification of Water in the,Soil — Capacity of Soil for Purification — Extent of Filtration Necessary to Eff^ect Purification — Spring-waters — Well-waters — Bacterial Content of Wells

— Effect of Pumping — Effect of Organic Nutriment on Growth of Water-bacteria

— Artesian Wells 169

Effect of Storage and Distribution on Quality. — Improvement of Water by

Storage — Impairment of Water by Storage — Effect of Distribution on Quality — Literature 177

CHAPTER X. communicable diseases and water-supplies.

Relation of Water-supplies to Disease Dissemination — The Germ-theory of Disease —

Specific Nature of Water-borne Disease-germs — Diseases Due to Parasitic Worms. 181

IiVFEcnous Diseases Transmissible by Water-supplies. — Conditions Necessary for Infection — Water-borne Diseases Affect Intestinal Canal — The Most Important Water-borne Diseases — Typhoid Fever — Typhoid Fever and Sewage Pollution — Mohawk Valley Epidemic — Lowell-Lawrence Epidemic — Pollution of Lake-towns

— Typhoid and Polluted Wells — Outbreaks Inaugurated from Single Cases — Typhoid Rates an Index of Quality of Water — Diminished Typhoid Rates Incident to Improved Supplies — Seasonal Distribution of Typhoid Fever — Asiatic Cholera

— Cholera Outbreaks traced to Water-supplies — Anthrax — Other Water-borne Diseases — Gastro-intestinal Disturbances — Dysentery — Malaria 183

Vitality of Pathogenic Bacteria in Water. — Conditions Affecting Vitality — Vitality of l^hoid Organism — Cholera — Anthrax — Literature 199

X CONTENTS.

PART n.

THE CONSTRUCTION OF WATER-WORKS.

CHAPTER XL

GENERALITIES PERTAINING TO WATER-WORKS CONSTRUCTION.

PAOB

General Arrangement of Water-works. — ClassiOcalion — Works for the Collection of Water — Works for the Purification of Water — Works for the Distribution of Water — Arrangement of Works — Systems of Operation — Comparison of the Various Systems — Existing Works as Affecting Choice — The Dual System 206

Prinoples of Economic Construction. — The General Problem — Methods of Comparing Cost — Method of Capitalization — Method of Annual Expense — Depreciation of Structures — Annuity Table — Provision for the Future — Estimates of Cost — Literature ai^

CHAPTER XII.

HYDRAULICS.

Purpose of the Chapter — Units of Measure — Notation — Weight of Water — Pressure

of the Atmosphere — Vapor Tension of Water — Pressure of Water 223

Flow of Water through Orifices. — Form and Proportion of Orifices — Flow through Small Orifices — Large Rectangular Vertical Orifices — Circular Vertical Orifices 226

Flow of Water over Weirs. — Sharp-crested Weirs — Submeiged Weirs — Weirs of Various Sections 228

Flow of Water through Pipes. — General Relations between Velocity and Pressure — Nature of Fluid-friction — General Formulas — Coefficients and Formulas for Cast-iron Pipes — Comparison of Various Formulas — Diagram Recommended for Use in the Design of Distributing Systems — Effect of Age of Service on Loss of Head — Friction Loss in Service-pipes — Coefficients for Riveted Pipes — Friction Loss in Wood-stave Pipe — Measurement of Flow through Large Pipes — Minor Losses of Head — Hydraulics of Fire-streams — Friction Loss in Fire-hydrants — Water-hammer 235

Flow of Water in Open Channels. — Formulas Employed — Measurement of Water

Flowing in Open Channels 256

A. WORKS FOR THE COLLECTION OF WATER.

CHAPTER Xni.

river and lake intakes.

General Conditions 259

River Intakes. — Location — Intakes in Large Streams Varying Little in Stage — intakes in Streams of Ordinary or Great Variation in Water-level — Intake-works for

Gravity-supplies ' 259

Lake Intakes. — Location — The Intake Conduit — Protection-works — Obstruction of Intakes by Anchor-ice — Literature 266

CONTENTS, XI

CHAPTER XIV.

WOKKS FOR THE COLLECTION OF GROUND-WATER.

PAGB

Classification 274

Works for Utilizing the flow from Springs. — Objects to be Attained — Ordinary

Forms of Collecting-basins — Methods of Increasing the Flow 274

The Hydrauucs of Wells. — A, Principles Governing the Flow into Ordinary Wells and Galleries — General Form of Ground-water Surface — Derivation of Formula for Flow — Calculation of Flow — Effect on the Yield of a Change in the Various Elements — Flow into Galleries — B, Principles Governing the Flow into Artesian Wells — C. Considerations of General Application — Pipe-friction and other Losses of Head — Effect of Depth of Well — Mutual Interference of a Number of Wells — Determination of Yield by Tests — Wells Sunk into Strata in which the Flow Takes Place through Fissures 277

Construction op Wells. — Forms of Construction — Location of Wells — Relative Advantages of Large and Small Wells — Large Open Wells — Size and Depth of Wells — Construction — Yield — Examples — 5Aa//<wi; Tubular W^«//j — Methods of Sinking — Strainers — General Method of Operating a Well-system — Arrangement and Spacing of Wells — Size of Well — Details of Connections — The Clogging of Wells — Tests — Yield — Examples — Deep and Artesian Wells — Comparison with Shallow Wells — Boring Deep Wells — Casing of Wells — Cost — Arrangement — Size and Spacing — Methods of Operation — Examples of Artesian-well Plants — Yields — Failure of Wells 292

Horizontal Galleries and Wells. — Filter-galleries — Examples — Tunnels in Rock — Wells and Galleries near Streams — Horizontal or Push Wells — Filter-cribs — Literature 318

CHAPTER XV. impounding-reservoirs.

Capacity. — Use and Value of Storage — Factors to be Considered — Appropriation of Surface-waters — Computation of Storage — Storage Calculation from the Sudbury River Records — Capacity of a System of Reservoirs 327

Location and Construction. — Considerations Affecting Location — Surveys and Preliminary Work — Depth of Reservoir — Cleaning the Site — Shallow Flowage — Maintenance — Literature 333

CHAPTER XVI.

EARTHEN DAMS.

General Considerations. — The Requisites of a Dam — Kinds of Dams — The Dam

as a Porous Structure 339

TBe Earthen Embankment. — Advantages and Requisite Conditions — Forms of Construction — Stability of the Various Forms of Embankments — Material for Embankments — Core-walls — Embankment-slopes — Height above Water-line — Width of Top — Preparing the Foundation — Construction of the Embankment — Hydraulic Dam-construction — Slope-protection — Embankments and Foundations of Porous Materia] — Outlet-pipes — Gate-chambers — Valves and Sluice-gates — Waste-weirs — Care of Floods during Construction — Cost — Literature. . 341

Xn X CONTENTS,

CHAPTER XVIL

MASONRY DAMS.

The Design. — General Conditions — The External Forces Acting upon a Dam — Internal Stresses — Conditions of Stability — Allowable Pressure — Weight of Masonry

— A. Stabiliiy of Low Dams — Calculation of Section — B. Stability of High Dams

— General Statement of the Problem — Wegmann's Method of Determining the Profile — Eflfect of Approximations in the Foregoing Treatment — Use of a Standard Profile — Approximate Triangular Profile — Forces not Considered in the Preceding Analysis — Top Width and Height above Water-line — Curved Dams 374

Construction. — The Foundation — Construction of the Masonry — Imperviousness

— Earth Backing for Masonry Dams — Draw-oflf Arrangements — Masonr>' Waste-weirs — Other Examples of Dams — Dams of the Buttress Type — Cost — Literature 392

CHAPTER XVIII.

TIMBER dams; STEEL DAMS; LOOSE-ROCK DAMS.

Timber Dams. — Use of Timber Dams — Examples of Timber Dams. . . ^ 412

LoosE-ROCK Dams. — Examples 414

Steel Dams. — Steel Cores — Dams Wholly of Steel — Literature 415

B. WORKS FOR THE PURIFICATION OF WATER.

CHAPTER XIX. objects and methods of purification.

Purification of Water for Manufacturing Purposes — Purification of Water for Domestic Purposes — Outline of Methods of Purification Employed — Literature 419

CHAPTER XX. sedimentation.

The Character of the Suspended Matter — Limitations of Artificial Sedimentation —

Methods of Sedimentation 424

Plain Sedimentation. — Action of Subsidence — Time Required for Subsidence — Bacterial EflSciency of Sedimentation — Bacterial Content of Reservoir Sediment — Experimental Data on the Action of Finely Divided Matter in Water 426

Sedimentation with Coagulation. — The Use of Coagulants — The Action of Various Coagulants — The Amount of Chemical Required — Time of Subsidence — Efficiency of Sedimentation with Coagulation 431

Settling-basins. — Methods of Operation — Number and Size of Basins — Form of Basin — Arrangement of Pipes, Continuous-flow System — Arrangement of Pipes, Intermittent System — Drain-pipes — Clear-water Well — Preparation and Control of Coagulant — Examples of Settling-basins — Literature 438

CHAPTER XXI.

SLOW SAND FILTRATION.

Historical — Types of Sand Filters 45©

Theory and Effiqency of Filtration. — General Results of Filtration — Theory of Filtration — Bacteria in the Effluent — Efficiency of Filtration — Passage of Bacteria Confirmed by Disease Outbreaks — Death-rates as Measures of Efficiency 453

CONTENTS, XIU

PAGB

Construction and Operation. — Rate of Filtration — Capacity — Number and Size of Beds — General Construction — Necessity of Covering Filters — The Filteringsand — Friction in the Sand-layer — Thickness of Sand-bed — The Depth of Water on the Filter — Drainage Systems — Loss of Head in the Drainage System — Maximum Total Loss of Head — Inlet-pipes — Outlet-pipes and Apparatus for Regulating the Head — Automatic Regulation — Other Pipes and Valves — General Arrangement of Piping — Pure-water Reservoir — Cleaning Filters — Period of Service — Efifect of Scraping on EflBciency of Filtration — Sand-washing — Bacterial Control of Filter Operations — Preliminary Treatment — Double Filtration — Intermittent Filtration — Literature — Cost of Fihers — Cost of Operation 461

CHAPTER XXII.

RAPID SAND filtration.

General Description of the Rapid Sand Filter — Types of Construction — Principles of Operation — Experiments on Rapid Filters and Results of Operation — General Arrangement of Plant — Details of Construction and Operation — Cost — Literature 502

CHAPTER XXIIL

MISCELLANEOUS PURIFICATION PROCESSES.

Special Forms of Filters — Aeration — Softening of Water — Chemistry of Watersoftening — General Features — Softening of Water for Boiler Use — Bacterial EflSciency of the Softening Process — Removal of Iron from Waters — Application of Electricity to Water-purification — The Anderson Revolving Purifier — Sterilization and Distillation — Purification by the Addition of Chemicals — Ozone — Chlorinated lime — Peroxide of Hydrogen — Copper Sulphate — Literature 530

C. WORKS FOR THE DISTRIBUTION OF WATER.

CHAPTER XXIV.

PIPES FOR CONVEYING WATER.

Materials Employed — Stresses to be Considered 551

Cast-iron Pipe. — General — Thickness and Weight of Cast-iron Pipe — Joints — Special Castings — Material and Method of Manufacture — Durability of Cast-iron

Pipe 555

Wrought-iron and Steel Pipe. — Advantages — Quality of the Material — Thickness

of Shell— Joints— Special Details— Coating of Steel Pipe— Durability of Steel Pipe 565 Wooden Pipe. — Advantages — Bored Pipe — Stave Pipe — General Requirements for

Staves and Bands — Size of Bands — Spacing of Bands — Coupling-shoes —

Specials — Leakage and Durability of Wooden Pipe 571

Other Materials Employed for Water-pipe. — Cement Pipe — Vitrified-clay Pipe

— Materials for Service Pipes — Literature 581

CHAPTER XXV.

CONDUITS AND PIPE-LINES.

Classes of Conduits — Capacity of Conduits — Single or Double Conduits — Location of Conduits 586

Canals. — Use of Canals — Slopes and Velocities — Cross-sections — Other Details — Flumes 589

XIV CONTENTS,

TAG»

Masonry Aqvxducts. — Advantages of Masonry Aqueducts — Size of Cro8s-«ection, Velocity and Slope— Materials Employed — Form and Stability of Section — Constructive Features — Special Details — ^Tunnels — Aqueducts of Vitrified Pipe . . 593

Pipe-lines. — The General Design — Material to be Employed — The Profile — Pressures to be Assumed — Calculation of Size of Pipe — Construction — Plan and Profile — Trenching — Foundations — Laying of Pipe — Testing and Inspection — Covering of Pipe — Appurtenances and Special Details — Provision for Expansion and Contraction — Manholes — Stop-valves — Air-valves — Blow-ofiF Valves — Sellacting Shut-off Valves — Check- valves — Pressure-regulation Devices — Terminal Arrangements — Crossings — Bridges — Protection of Exposed Pipes — Submerged Pipes 601

Cost of Conduits and Pipe-unes. — Canals and Masonry Aqueducts — Pipe-lines — literature 624

CHAPTER XXVI. pumping-uachinery.

Introductory — Energy Expended in Pumping Water — Work and Power Equivalents — Classification of Energy Losses 630

Sources of Potential Energy. — Available Sources — Fuel — Water-power. 636

Generation and Conversion of Energy. — Ordinary EflBciency of Generators and Motors — The Steam-boiler — The Steam-engine — Use of Steam Expansively — Use of Condensers — Average Steam Consumption — Effect of Operating at Part Load — Heat-engines 637

The Transmission of Energy. — Methods of Transmission and General Efficiencies — Direct Connection — Shafting — Gearing — Belts — Rope Transmission — Wire-rope Transmission — Pneumatic Transmission — HydrauUc Transmission — Electrical Transmission 644

The Pump in General. — Classification of Pumps — (i) Displacement Pumps — Reciprocating Pumps — The Steam-pump — Rotary Pumps — Air- and Steam-displacement PumjK — Continuous-flow Pumps — (2) Impeller Pumps — Action of Impeller Pumps — The Centrifugal Pump — Jet-pumps — (3) Impulse Pumps — (4) Bucket Pumps 649

Pump Details. — General Rules — Valves — Air- and Vacuum-chambers — Suction-pipes — Location of Pum ping-machinery with Respect to the Level of the Water Drawn From 663

Duty and EpFiaENCY of Pumping-machinery. — Measures of Duty — Ordinary Duty and Eflidency of Pumping-machinery — Methods of Analyzing Power Losses — Capacity of Pumping-machinery — Comparison of the Economy of Different Designs

— Examples — Literature 670

CHAPTER XXVIL

distributing and equalizing reservoirs.

Office — Kinds of Reservoirs — Capacity — Location — Elevation 689

Earthen and Masonry Reservoirs. — Form and Arrangement — Depth — Embankment Construction — Linings — Masonry Walls — Arrangement of Pipes, Valves,

etc. — Covered Reservoirs — Masonry Reservoirs — Cost 694

Stand-pipes and Tanks. — Capacity — Location — Stand-pipes — General Proportions— Forces and Stresses — Material Employed — Plate Thickness — Riveting

— Bottom Details — Foundation and Anchorage — Pipes and Valves — Other

I

Digitized by VjOOQ I

CONTENTS. XV

PAGS

Details — Encased Stand-pipes — Eievaled Tanks — Economy, Form, and Proportions— Stresses in Tank — The Tower — Anchorage — Inlet Pipe — Masonry Towers — Wooden Tanks — Reinforced Concrete Tanks — Storage of Water under Pressure *- Literature 7x1

CHAPTER XXVIII.

THE DISTRIBUTING SYSTEM.

General Requirements — The Pressure Required — Number and Size of Fire-streams ^ Location of dydrants — General Arrangement of the Pipe System — Maxindum Rates of Supply for Different Areas — Velocities of Flow for Fire Supplies — Loss of Head in Distributing-pipes — General Problems Pertaining to the Flow through Compound Pipes — Calculation of the Pipe System — Separate Services for Different Zones of Elevation' — Location of Pipes and Valves — Hydrants — Depth of Covers Sxkg for Distributing-pipes — Service Connections — Other Details — Special Firepiotection Systems — Records and Maps — Literature 742

CHAPTER XXIX.

OPERATION AND MAINTENANCE.

Conduits and Pipe-lines — Pumping-stations — Distributing-reservoirs, Stand-pipes, and Tanks. 7 7^

The Distributing System. — Mains and Service-pipes — Valves and Hydrants — Detection and Prevention of Waste — Metere 781

Financial. — General Considerations — Expenses and Charges to be Met — Relati'^e Cost of Diffeient Services — Souices of Revenue — Water Rates — Literature. ... 789

PUBLIC WATER-SUPPLIES.