Chapter XXI: Automatic Dosing Devices

=283. Types.=—Automatic dosing devices are used to apply sewage to contact beds, trickling filters, and intermittent sand filters. These devices can be separated into two classes; those with moving parts and those without moving parts. The latter are better known as air-locked dosing devices. Simple devices without moving parts are less liable to disorders and are nearer “fool-proof” than any device depending on moving parts for its operation.

No one type of moving part device has been used extensively in different sewage treatment plants. Designing engineers have exercised their ingenuity at different plants, resulting in the production of different types.[207] Among the best known forms is the apparatus designed by J. W. Alvord for the intermittent sand filters at Lake Forest, Illinois.[208] In its operation....

A float in the dosing chamber lifts an iron ball in one of a
series of wooden columns, and at a certain height the ball rolls
through a trough from one column to the next, in its passage
striking a catch, which opens an air valve attached to one of ten
bell-siphons in the dosing chamber. Each of the siphons discharges
on one of the ten sand beds, which are thus dosed in rotation.

Since air-locked dosing devices are in more general use their operation will be explained in greater detail.

=284. Operation.=—The simplest form of these devices is the automatic siphon used for flush-tanks, the operation of which is described in Art. 61.

In the operation of sand filters, sprinkling filters, or other forms of treatment where there are two or more units to be dosed it is desirable that the dosing of the beds be done alternately. A simple arrangement for two siphons operating alternately is shown in Fig. 182. They operate as follows: with the dosing tank empty at the start water will stand at _bb′_ in siphon No. 2 and at _aa′_ in siphon No. 1. As the water enters through the inlet on the left the tank fills. When the water rises sufficiently, air is trapped in the bells, and as the water continues to rise in the tank, surfaces _a_ and _b_ are depressed an equal amount. When _b_ has been depressed to _d_, _a_ has been depressed to _c_. Air is released from siphon No. 2 through the short leg, and siphon No. 2 goes into operation. Surface _c_ rises in siphon No. 1 as the tank empties and when the action of Siphon No. 2 is broken by the admission of air when the bottom of the bell is uncovered the water in siphon No. 1 has assumed the position of _bb′_ and that in No. 2 is at _aa′_. The conditions of the two siphons are now reversed from that at the beginning of the operation and as the tank refills siphon No. 1 will go into operation. It is to be noted that these siphons are made to alternate by weakening the seal of the next one to discharge and by strengthening the seal of the one which has just discharged.

FIG. 182.—Diagram Showing the Operation of Two Alternating Siphons.
]

FIG. 183.—Diagram Showing the Operation of Three Alternating Siphons.
]

=285. Three Alternating Siphons.=—This principle can be extended to the operation of three alternating siphons as shown in Fig. No. 183. These operate as follows: with the dosing tank empty at the start and water at _aa′_ in siphons 1 and 2, and at _bb′_ in siphon No. 3, the dosing tank will be allowed to fill. As the water rises in the tank air is trapped in all the bells and surfaces _a_ and _b_ are depressed. When surface _b_ has been depressed to _d_, _a_ has been depressed to _c_. Air is released from siphon No. 3 and this siphon goes into action. Surface _c_ rises in siphons 1 and 2 to the position _b_, as the dosing tank is emptied. At the same time a small amount of water is passed from siphon No. 3 to the short leg of siphon No. 1, through the small pipes shown, thus filling this leg so that when siphon No. 3 ceases to operate the water in siphons 1 and 3 stands at _aa′_ and that in No. 2 stands at _bb′_. Siphon No. 2, having the weaker seal, will be the next to operate. During its operation it will fill siphon No. 3, leaving No. 1 weak. When No. 1 operates it will refill No. 2, leaving No. 3 weak, thus completing a cycle for the three siphons. This principle has not been applied to the operation of more than three alternating siphons and is seldom used on recent installations.

FIG. 184.—Miller Plural Alternating Siphons.

Courtesy, Pacific Flush Tank Co.
]

=286. Four or More Alternating Siphons.=—An arrangement for the alternation of four or more siphons is illustrated in Fig. 184. At the commencement of the cycle it will be assumed that all starting wells are filled with water except well No. 1, and that all main and all blow-off traps are filled with water. The following description of the operation of the siphons is taken from the catalog of the Pacific Flush Tank Company:

The liquid in the tank gradually rises and finally overflows into
the starting well No. 1 and the starting bell being filled with
air, pressure is developed which is transmitted, as shown by the
arrows, to the blow-off trap connected with siphon No. 2. When the
discharge line is reached, sufficient head is obtained on the
starting bell to force the seal in blow-off trap No. 2, thus
releasing the air confined in siphon No. 2 and bringing it into
full operation.

During the time that siphon No. 2 is operating, siphonic action is
developed in the draining siphon connected with starting well No.
2 and as soon as the level in the tank is below the top of the
well it is drained down to a point below the bottom of starting
well No. 2. It can now be seen that after the first discharge
starting well No. 2 is empty, whereas the other three are full....
Therefore when the tank is filled the second time, pressure is
developed in starting bell No. 2, which forces the seal of
blow-off trap No. 3, thus starting siphon No. 3....

This alternation can be continued for any number of siphons. Other arrangements have been devised for the automatic control of alternating siphons, but these principles of the air-locked devices are fundamental.

=287. Timed Siphons.=—In the operation of a number of contact beds not only must the dosing of the tanks be alternated, but some method is needed by which the beds shall be automatically emptied after the proper period of standing full. To fulfill this need the principle of the timed siphon must be employed in conjunction with the alternating siphons. Fig. 185 illustrates the operation of the Miller timed siphon. Its operation is as follows: water is admitted to the contact bed and transmitted to the main siphon chamber through the “opening into bed.” Water flows from the main siphon chamber into the timing chamber at a rate determined by the timing valve. The contact bed is held full during this period. As the timing chamber fills with water air is caught in the starting bell and the pressure is increased until the seal in the main blow-off trap is blown and the main siphon is put into operation. As the water level in the main siphon chamber descends, water flows from the timing chamber into the main siphon through the draining siphon and the timing chamber is emptied, ready to commence another cycle.

=288. Multiple Alternating and Timed Siphons.=[209]—The alternating and timing of a number of beds is more complicated. The arrangement necessary for this is shown in Fig. 186. It will be assumed at the start that all beds are empty and that all feeds are air locked as shown in Section _AB_ except that to bed No. 4 into which sewage is running. As bed No. 4 fills, sewage is transmitted through the opening in the wall into the timed siphon chamber No. 4. When the level of the water in the bed and therefore in this chamber has reached the top of the withdraw siphon leading to the compression dome chamber No. 4, this latter chamber is quickly filled. The air pressure in starting bell No. 4_a_ is transmitted to blow-off trap No. 1_a_. The seal of this trap is blown, releasing the air lock in feed No. 1 and the flow into bed No. 1 is commenced. At the same time the air pressure in compression dome No. 4 is transmitted to feed No. 4, air locking this feed and stopping the flow into bed No. 4. The alternation of the feed into the different beds is continued in this manner.

FIG. 185.—Miller Timed Siphon.

Courtesy, Pacific Flush Tank Co.
]

Bed No. 4 is now standing full and No. 1 is filling. When compression dome chamber No. 4 was filled, water started flowing through timing siphon valve No. 4 into timing chamber No. 4 at a rate determined by the amount of the opening of the timing valve. As this chamber fills compression is transmitted to blow-off trap 4_b_ and when sufficiently great this trap is blown and timed siphon No. 4 is put into operation. Bed No. 4 is emptied by it, and compression dome chamber No. 4 is emptied through the withdraw siphon at the same time. This completes a cycle for the filling and emptying of one bed and the method of passing the dose on to another bed has been explained. The principle can be extended to the operation of any number of beds.

FIG. 186.—Plural Timed and Alternating Siphons for Contact Bed
Control.

Courtesy, Pacific Flush Tank Co.
]

INDEX

A. B. C. process of sewage treatment, 4

Abandonment of contract, 225

Access to work, 228, 229

Accident, contractor’s responsibility, 221, 224

Acetylene, explosive, 347

Acid precipitation. _See_ Miles Acid Process.
of sludge, 503

Acids as disinfectants, 489, 490

Activated sludge. Chapter XVIII, 465–479
advantages and disadvantages, 469, 470
aëration tank, 471, 472
air diffusion, 475, 477
air distribution, 473–478
air quantity, 475, 476
area of filtros plates, 478
colloid removal, 358
composition, 465–469
cost, 478, 479
definition, 466
dewatering, 468, 469, 497–505
fertilizing value, 469, 470
historical, 470, 471
how obtained, 478
nitrogen content, 468
patent, 471
process, 465
quantity, 469
reaëration tank, 473
results, 467, 468, 476
sedimentation tank, 472

Advertisement, 214

Aëration, effect on oxygen dissolved, 373–375
of sewage, 371, 376, 465–479

Aërobes, 363

Aërobic decomposition, 366, 367

Aftergrowths, 492

Aggregates, specifications, 172–174

Air, see also ventilation, activated sludge, compressed air, etc.
ejectors, 150
lock dosing apparatus. Chap. XXI, 506–512
machinery for activated sludge, 473, 474

Algæ, 363

Alkalinity, 358

Alleys, sewers in, 80

Alum, 407, 408

Alvord tank, 427, 429

Ammonia, 366, 367, 374, 375, 410
explosives, 297

Analyses, bacteriological, 364
chemical, 354, 355
mechanical of sand, 182
physical, 352–354
sewage, 352–364

Anaërobes, 363, 365–367

Anaërobic, action, 410
bacteria, 363
conditions, 367
decomposition, 365–367

Ann Arbor, Michigan, Population, 14

Annual expense, method of financing, 157, 158

Ansonia air ejector, 150, 151

Antibiosis, definition, 363

Appurtenances to sewers. Chap. VI, 99–115

Arch, analyses, 204–208
elastic method, 206–208
vouissoir analysis, 204–206
brick construction, 312, 313
centers for brick sewers, 313
concrete construction, 318–321

Ardern and Lockett, development of activated sludge, 467, 468, 471

Area of cities, 31

Asphyxiation in sewer gas, 336

Assessments, special, 15, 16

Augers, earth, 21

Automatic, regulators, 117–121
siphons, flush-tanks, 110
double alternating, 507
multiple alternating, 508–512
timed, 510
timed and multiple alternating, 510–512
triple alternating, 508

Bacillus, definition and morphology, 362, 363

Backfilling, 328–331

Backfill, puddling, 330
weight of, 199, 201

Backwater curve, 73

Bacteria, definition and morphology, 362, 363
good and bad, 363, 364
nature of, 362, 363
nitrifying, 431, 432
sanitary significance of, 364
in sewage, 362, 363
total count, 364

Bacterial analyses, results in sewage, 364

Baffles, scum, 404, 413, 414, 421
in sedimentation tanks, 404
in septic tanks, 413, 414
in Imhoff tanks, 421

Balls, for cleaning sewers, 338

Band screen, 384

Barring, definition, 263

Bars for screens, 390

Basins, sedimentation, baffling, 404
bottoms, 404
cleaning arrangements, 404
depth, 401
economical dimensions, 401–403
inlets and outlets, 404
scum boards, 404
types, 395

Basket handle sewer section, 67, 69

Bathing beaches, pollution, 381

Bazin’s formula, 54

Bearings, for centrifugal pumps, 131, 137, 138
thrust, 138

Bellmouth, 121, 122

Bends in pipe, loss of head in, 116

Berlin, sewage farm, 460, 461
sewers, date of, 3

Bids, proposal, 217–219

Bidder’s duties, 215–217

Bio-chemical oxygen demand, 359–361

Biolysis of sewage, 366, 367

Black and Phelps dilution formulas, 377–379

Blasting and explosives, 294–304
caps, 297, 299, 300
detonators, 294, 297–300
firing, 302–304
fuses and detonators, 297–300
fuses, delayed action, 291, 300
fuses, electric, 299, 300
splicing, 303
gelatine, 296
loading holes, 303
powder, 295
precautions, 300–302
priming and loading, 303
rock, 269
size of charge, 304, 305
tunneling, 290, 291

Bleach, characteristics of for disinfection, 491

Block sewer, construction, 311–314
hollow tile as underdrains, 126

Blocks, vitrified clay, 189, 190

Boilers, steam, 147–150

Boilers, efficiencies, 149
horse-power, 149

Bond, contractor’s, 213, 214, 232
issues, 14

Bonds, definition and types, 14–16

Boring underground, 20

Bottom, activated sludge aëration tank, 472
Imhoff tanks, 423
sedimentation tanks, 404
trickling filter, 451, 452

Box sheeting, 272

Branch sewer, defined, 7

Breast boards, 288

Brick, arch construction, 312, 313
and block sewer construction, 311–315
invert construction, 311, 312
sewer construction, 311–315
arch centers, 313
invert, 311–312
organization, 314, 315
progress, 314
row lock bond, 312
specifications, 188, 189
sewers, life of, 351

Bricks for sewers, 316

British Royal Commission on Sewage Disposal, 4

Broad irrigation. _See_ under Irrigation.

Bucket excavators, 246, 255, 256

Building material, weight of, 201

Burkli-Ziegler formula, 47, 425

Butyrine, 366

Cableway excavators, 246, 250–252

Cage screen, 384, 385

Caisson excavation, 285, 286

Calcium carbide, explosive, 347

Calumet pumping station, 128, 142

Cameron septic patent, 411

Capacity of sewers, diagrams, 57–60

Capital, private invested in sewers, 17

Capitalization, method of financing, 157–160

Caps, blasting. _See_ blasting.

Carbohydrate, 366, 367

Carbon, analysis for, 356
dioxide, 366, 367

Carson Trench machine, 250, 251

Cast-iron pipe, 122, 164, 190, 191
joints, 164
quality, 101, 102, 190

Castings, iron, 101, 102

Catch-basins, 99, 107–108, 217
cleaning, 343, 344
inspection, 337

Catenary sewer section, 69

Cellars, depth of, 88

Cellulose, 367

Cement. _See also_ Concrete,
pipe, specifications, manufacture and sizes, 171–179
vs. concrete, 164

Centrifugal pumps. _See_ pumps, centrifugal.

Centrifuge for sludge drying, 501, 502

Cesspool, 411, 416, 417

Champaign, Illinois, septic tank, 415, 416

Changes in plan, 222, 223

Channeling, definition, 263

Character of surface, 44

Chemical analyses, 354–362

Chemical precipitation, 371, 405–409
chemicals used, 405–407
preparation of chemicals, 407, 408
results, 408, 409
at Worcester, 408

Chezy formula, 52, 53

Chicago. _See also_ Sanitary District of Chicago.
drainage canal, 374, 375
dilution requirement for sewage, 380
early sewers, 3
method of sewage disposal, 374
population and density, 29, 30
trench excavation in, 248

Chlorine. _See also_ Disinfection.
disinfectant, 489–493
in sewage, 358, 374, 375

Chlorine liquid, application, 491, 492

Cholera, transmittable disease, 364

Chromatin, 365

Chutes for concrete, 187

Circular sewer section, hydraulic elements, 65, 66, 69
types, 70, 71

City, growth of area, 31
growth of population, 24–28
legal powers, 219

Clay, life of pipe, 349–351
manufacture of pipe, 165–167
specifications for pipe, 168–170
unglazed for pipe, 165
vitrified blocks, 167, 189, 190
vitrified pipe, 165–171

Cleaning, grit chambers, 398, 400
sedimentation basins, 404
sewers, cost, 341
in N. Y. City, 332
methods, 337–343
tools, 338–340
up after completion of work, 228

Coccus, 362

Coefficient of uniformity of sand, 456

Coffin sewer regulator, 117, 118

Colloid, nature of, 358
treatment for, 358

Color of sewage, 352, 353

Combined sewer system, 78, 79

Commercial districts, characteristics of and sewage from, 32, 34, 35

Compensators for pumps, 142

Compressed air. _See also_ ventilation, tunneling, drilling, etc.
activated sludge, 473–475
for drilling, 264–268
in tunnels, 292–294
transporting concrete, 320, 321

Concentration, time of flood flow, 41–43, 96, 97

Concrete, aggregates, 172–174
mixing and placing, 184–188
pipe, details, 175–179
manufacture, 171–179
reinforcement, 177, 178, 209, 210
pipe, steam process, 176
sizes, 175
pressure against forms, 232, 323

Concrete, proportioning, 179–183
qualities, 179, 180
reinforcement, placing, 178, 326, 327
reinforcing steel, quality, 191
sewer construction, 314–328
arch, 318–321
form length, 319
labor costs, 327, 328
in open cut, 314–320
in tunnel, 320, 321
invert, 315–320
organization for, 328
working joints, 319
sewer costs, 327–329
strength, 181
waterproofing, 184

Conduits, special sections, 67, 70, 71

Connections to sewers, ordinances, 344, 345
record of 92, 238

Construction of sewers, Chap. XI, 233–331

Construction, elements of, 233
organizations, 315, 328

Contact bed, 432–437, 506
advantages and disadvantages, 432–434
automatic control, 437, 506
cleaning, 435
clogging, 435
construction, 434–436
control, 437, 506
cycle, 436, 437
depth, 434
description, 432, 433
design, 434–436
dimensions, 434, 435
loss of capacity, 435
material, 435, 436
multiple, 433, 435
operating conditions, 432–437
rate, 435
results, 433, 434
ripening, 432

Continuous bucket excavators, 246–250

Contour interval on maps, 79, 80

Contracts, Chap. X, 211–232
abandonment of, 225
assignment, 228
completion of, 222, 228
bond, 213, 222
content, 213, 230, 231
cost-plus, 212, 213
disputes, 220
divisions of, 213
drawings, 213
engineer as an arbitrator, 220
the instrument, 230, 231
interpretation of, 220, 234, 235
lump sum, 212
nature of, 211, 212
sample, 230, 231
time allowed, 222
types, 212, 213
unit-price, 213

Contractor, absence of, 222
bond, 232
claims against, 228
duties, 221
liability, 224
relations with other contractors, 228, 229

Contractor’s powder, 294

Control devices, automatic, for sewers, 117–121
for filters, 500–512
inspection of, 336, 337

Copper sulphate, disinfectant, 490

Copperas, precipitant, 406–408

Cordeau Bickford, 298, 303

Corrugated iron pipe, 165

Cost. _See_ under item wanted.

Cost, annual. Method of financing, 157–160
capitalized. Method of financing, 157–160
classification of, 235–238
comparisons of. Methods for
making, 157–160
collection of data, 10–14, 235–238
estimate. Method of making, 10–14
overhead, 237, 238

Couplings, flexible for shafts, 138

Covers, Imhoff tanks, 424
septic tanks, 415
trickling filters, 451

Crops on sewage farms, 463, 464

Cunette, 67, 70

Cut, depth of excavation, 88, 92

Cycle, contact bed, 436
life and death, 367, 431
nitrogen, 367, 368
trickling filter, 441

Cylinders, stresses in, 194, 202–204

Cytoplasm, 365

Damages, liquidated, 222
material, 221, 224

Darcy’s formula, 52

Day labor, 211

Decomposition of sewage, 365–367

Definitions. _See_ word defined.

Deflagration, definition, 294

Delays in contract work, 228

Delayed action fuses, 291, 300

Densities. _See_ population.

Depreciation, of sewers, 348–351
rate of, financial, 158

Depth of sewers, 88

Design conditions, 88–92
economical, mathematics of, 401–403
preparations for, 17–23

Detention period, grit chamber, 397
Imhoff tank, 419
plain sedimentation, 392–395, 401
septic tank, 415

Detonation, definition, 294

Detonator. _See_ blasting cap.

Diameter of sewers, 57–60, 72, 88–92

Diaphragm pump, 257, 258

Diesel engine, 152, 154

Digestion chamber, Imhoff tank, 422, 423

Digestion of sludge in separate tank, 427–430, 497

Dilution, amount needed, 377–380
conditions for success, 372, 373

Dilution, definition, 372
formulas for quantity, 378–380
governmental control, 380, 381
preliminary studies, 381, 382
in salt water, 376, 377
in streams, 372–376
of sewage, 370 and Chap. XIV, 372–382

Diseases, water-borne, 364

Disinfection, 489–493
action of, 489–491
bleaching powder, 491
chlorine, liquid, 491
amount of, 492
disinfectants, 489, 490
purpose, 489
selective action of disinfectants, 492, 493

Disk screen, 384

Disposal of sewage, _See_ sewage treatment.

Disputes, engineer to settle, 220

Dissolved oxygen. _See_ Oxygen dissolved.

Distribution of sewage,
contact beds, 436
irrigation, 461, 462
nozzles, 442–449
sand filter, 450–458
traveling distributor, 442
trickling filters, 441–451

Districts, character of, 29, 30, 32–37
classification of, 34, 35

Domestic sewage, defined, 6, 7, 352

Dorr Thickeners, 472, 504

Dortmund tank, 404

Dosing devices, 506–512
alternating and timed siphons, 500–512
Alvord device at Lake Forest, 506
four or more alternating siphons, 509
operation of automatic siphon, 110
three alternating siphons, 508
timed siphons, 510
two alternating siphons, 507
types, 506

Dosing tank design, for trickling
filter, 446–450

Doten tank, 429, 430

Drag line excavators, 255, 256

Drainage areas, 81, 84, 94

Drills, electric, 267
jack hammer, 264, 265
punch, 20
size of cylinder for, 266
tripod, 264, 265

Drilling, methods, 20–23, 264–270
depth, diameter and spacing of
holes, 268–270
power for, 267, 268
rate of, in rock, 267
steam and air, 267, 268

Drop manhole, 100, 101

Drop-down curve, 73, 77

Drum screen, 384

Dry weather flow, 24, 38

Drying sludge. _See_ sludge drying.

Dualin, 296

Duty of contractor. _See_ Contractor, duties

Duty of engineer. _See_ Engineer, duties.

Duty of inspector. _See_ Inspector, duties.

Duty of a pump, defined, 135

Dynamite, 296–298, 300–302, 304, 305
cartridge, 268, 296, 302
thawing, 301, 302

Dysentery, 365

Earth pressures, theories, 274, 275

Economical dimensions, mathematics of, 401–403

Effective size of sand, defined, 456

Efficiency of a pump, defined, 135

Effluents, character of
activated sludge, 467, 468
chemical precipitation, 408
contact bed, 434
Imhoff tank, 414, 424, 425, 432
lime and electricity, 489
Miles acid process, 484, 485
sand filter, 453

Effluents, sedimentation tank, 401
septic tank, 412–414

Egg-shaped section, 67, 68, 70

Ejectors, air, 150, 151

Elastic arch analysis, 206–208

Electric motors, 150–152

Electrolytic treatment, 487–489

Elevations, method of recording, 92

Emergencies, duties of engineer, 235

Emerson pump, 261

Engines, internal combustion, 152–154
steam, types, 142–144.

Engineer, absence of, 221
defined, 220
disputes settled by, 220, 234
duties of, 9, 10, 220, 233, 234, 238
individuality and personality, 9, 234
qualifications, 9
sanitary, definition, 2

Engineering News pile formula, 125, 126

Entering sewers, precautions, 335, 336

Enzymes, 365

Equipment for construction, 237

Equivalent sections, defined, 72
solution of problems in, 67–72

Estimates, cost and work done, 10–14
when made, 226
data for, 235

Excavation, depth of open cut, 284
drainage, 252, 262
hand, 242–245, 249
economy, 245
laborer’s ability, 243
lay out of tasks, 243

Excavation, hand, opening trench, 243
vs. machine, 245, 249
tools, 242
machine, 244–246
economy, 245
limitations, 246
vs. hand, 245, 249
specifications, 240, 241

Excavating machines, bucket, 246, 255
cableway and trestle, 246, 250–252
Carson machine, 250, 251
continuous belt, 246
bucket, 246, 247
drag line, 255
Potter machine, 251
steam shovel, 252–254
tower cableway, 252
wheel excavators, 246–250

Excavation, machine, organization, 249
pumping and drainage, 256, 257
quicksand, 256
rock, 263, 264
payment for, 230
specifications, 240, 241
trench bottom, 241, 304, 311

Explosions in sewers, 108, 336, 346–348
causes of, 346
historical, 346
prevention, 108, 348

Explosives. _See also_ Blasting.

Explosives, and blasting, 294–304
ammonia compounds, 297
blasting gelatine, 296
contractor’s powder, 294
deflagrating, 294
detonating, 294
detonators, 294, 297–300
“Don’ts,” 300, 301
dynamite, 296–298, 300–302, 304, 305
fuses and detonators, 297–300
gelatine dynamite, 296
gunpowder, 295
handling, 300–302
nitro-glycerine, 295
nitro-substitution compounds, 295
permissible, 297
quantity, 304, 305
requirements, 294
strength of, 297, 298
T.N.T., 295
types, 294–297

Exponential formulas for flow of water, 54, 55

Extra work, compensation, 227

Facultative bacteria, 363

Fanning’s run-off formula, 49

Farms, septic tanks for, 416, 417

Farming with sewage. _See_ irrigation.

Fats in sewage, 357–359, 366, 367
from Miles acid process, 485–487

Feathers, for splitting rock, 264

Ferrous sulphate, precipitant, 406–408

Fertilizer from sludge, 470, 495, 497

Fertilizing value of, activated sludge, 470
sewage, 459, 460

Filter press for sludge, 500, 501

Filters. _See_ under name of filter.

Filtration, of sewage, 370, 371, 431–459
action in, theory of, 431
cost, 458, 459

Filtros plates, 477, 478

Finances, mathematics of, 157–160

Financing, methods of, 14–17

Flamant’s formula, 54, 56

Flies on trickling filters, 438

Flight sewer, 101, 102

Flood, crest velocities, 42, 43
flow computations, 94–98
McMath formula, 94, 96, 97
Rational method, 95–98

Flow, laws of, 52
velocity of, 52, 90, 91

Fluctuations, in rate of sewage flow, 33–38
in quality of sewage, 368–370

Flush-tanks, automatic, 109–113
capacity, 111
details, 110, 112
inspection of, 336, 337
payment for, 217
siphon sizes, 111

Flushing, 109–113, 341–343
amount of water needed, 112
methods, 341–343
manhole, 109
sewer, defined, 8

Foaming of Imhoff tanks, 425, 426

Foot valves, 141

Force main, defined, 8

Forms, design of, 322, 323
length of, 319
materials, 321, 322
oiling, 174, 186, 322
specifications, 322
steel, 325, 326
steel-lined, 325
support for, 316, 318
time in place, 319
wooden, 323, 324

Formulas, hydraulic, methods for solution, 55–61
for flow of water, 52–55
for rainfall. _See_ Rainfall,
for run-off. _See_ Run-off.

Foundations, 99, 124–126

Franchises for sewers, 17

Free ammonia, 366, 367, 374, 375, 410

Freezing, catch-basins, 108
concrete, 186, 187
dynamite, 301, 302

Fresh sewage, characteristics, 352–354

Friction losses. _See_ Head losses.
flow in pipe, 51, 52

Fuel, consumption by prime movers, 153
costs, 153
heat value, 150

Fungus growth in sewers, 333

Fuses. _See_ blasting fuses.

Ganguillet and Kutter’s formula, 52–65

Gas, chamber in Imhoff tank. _See_ Scum chamber.
engines, 152–154
illuminating, explosive, 347
sewer, 335, 336

Gasoline, explosive, 108, 109, 335, 346, 347
engines, 152–154
and oil separator, 109
odors, significance, 335, 353

Gearing, reduction for turbines, 140, 146

Gelatine dynamite, 296

Glycerol, 366

Gothic section, 67

Governmental control, stream pollution, 380, 381

Grade, of sewers. _See also_ Slope.
how given, 281–284
selection of, 90
stakes, 221, 281–283

Gravel, specifications, 172

Grease, in sewers, 99, 108, 333, 345
cutter, 340
ordinance concerning, 345
traps, 99, 108

Gregory’s imperviousness formulas, 44, 46

Grit, clogs sewers, 333
chambers, 127, 397–401
description, 395, 398
design, 397, 398
dimensions, 397, 398
existing, 398–400
outlet arrangements, 400
results, 397
retention period, 397
sludge analyses, 397
units, number of, 400, 401
velocity of flow in, 396–398
quantity and character of, 397

Grooves in concrete, working joints, 319

Ground water in sewers, 38, 39, 85, 87, 256, 352

Gun cotton, 296

Gunpowder, 295

Hazen, theory of sedimentation, 392–395
dilution formula, 380

Hazen and William’s formula, 55, 57

Head loss, in bends, 116
entrance, 115
friction in straight pipe, 51, 52, 115

Hercules powder, 296

Hering, Rudolph, dilution recommendations, 380

Hering, Rudolph, introduction of Imhoff tank and hydraulic formulas,
425

Historical résumé of sewerage and sewage treatment, 2–5

Hitch, tunnel frame, 286, 287

Holes, drill. _See_ Drill holes.

Holidays, work on, 221

Hook for lifting pipe, 304, 306

Horse-power, boiler, 149, 150
of pumps, 144–146

Horseshoe sewer section, 71

House, connections, record of, 92, 234
drains, 7, 88, 90
sewer, defined, 7

Hydraulic, elements, 65, 69
formulas, 52–55
jump, 73–74
principles, 51, 52, 72, 73
value of settling particles, 393

Hydraulics of, sewers, Chap. IV, 51–77
circular pipes partly full, 65, 66
equivalent sections, 72
non-uniform flow, 72–77
sections other than circular, 67–72
use of diagrams, 61–65

Hydrocarbon, 367

Hydrogen sulphide, 353, 366, 410

Hydrolytic tank, 427, 428

“Hypo” as a disinfectant, 491

Hytor Turbo blower, 473, 474

Illinois River, self-purification, 374–376

Imhoff tank, and chlorination, costs, 487
cover, 424
description, 417–419
design, 419–424
digestion chamber, 422
inlet and outlet, 421
operation, 426–427
patent, 418
results, 414, 424, 425, 439, 467
sedimentation chamber, 419–422
scum chamber, 424
slot, 422
sludge, 414, 467
sludge pipe, 423, 424
status, 425, 426
and trickling filter, cost, 479

Impeller, for centrifugal pump, 131, 136

Imperviousness, relative, 40, 42, 44–46, 95–97

Industrial, districts, 32–37
wastes, defined, 7, 352
tannery, 491

Information and instructions for bidders, 213, 215–217

Inlets, street, 93, 94, 99, 104–107

Inspection, contract stipulations, 221–224
during construction, 233, 234
for maintenance, 104, 333–337, 348, 349

Inspector, absence of, 221, 222
duties, 233–234
qualifications, 234

Institutional sewage treatment plants, 416, 417

Intercepting sewer, defined, 7

Intermittentsand filter. _See_ Sand filter.

Internal combustion engines, 152–154

Inverted siphon, 113–116

Iron, ferrous sulphate, precipitant, 406–408
cast. _See_ cast iron.

Irrigation. _See also_ Farming and Sewage farming.
area required, 463
Berlin sewage farm, 460, 461
crops, 463, 464
description, 459
fertilizing value of sewage, 460, 470, 495, 498
vs. farming, 459
operation, 461–463
preliminary treatment, 462, 463
preparation for, 461–463
process, 459, 460
sanitary aspects 463
status, 460, 461
theory, 432
in the United States, 461

Jack hammer drill, 264, 265

Jetting method, 21–23

Jet pump, 259, 341, 343

Joints, bituminous, 309–311
in cast-iron pipe, 164
cement, 307, 308
inspection of, 234
lead, 164
mortar, 307
open, 307
poured, 309–311
cement, 309, 311
riveted steel, 195, 196
sulphur and sand, 309
types, for pipe, 307
working, in concrete, 319

Junctions, 99

Kuichling, run-off rules, 46, 47, 49
storm intensity formulas, 50

Kutter’s formula, 52–65

Labor, day vs. contract, 211
costs on concrete sewer, 328, 329

Labyrinth packing rings, 136, 137

Lagging, tunnel frames, 287
for forms, 322

Lagooning sludge, 495–497

Laitance, 186, 188

Lakes, self-purification of, 376

Lampé’s formula, 54

Lampholes, 99, 104

Lateral sewer, defined, 7

Lawrence Experiment Station, 4

Leaping weir, 118–121, 337

Legal requirements, construction, 224
dilution, 380, 381
in design, 9

Liernur system, 5

Life, organic in sewage, 363, 364
of sewers, 348–351

Lime as a precipitant, 405–408
with electricity, 488, 489
with iron, 406, 407

Line and grade, 281–284
how given, 281–283

Liquefaction of sludge, 411–413, 496, 497

Liquid chlorine. _See also_ Chlorine, 491

Liquidated damages, 222

Loads on, pipe, 198–202
Marston’s method, 198–202
trench, 199–202

Lock bar pipe, 197

Lock-joint pipe, 177

Long loads, 201

Machine excavation. _See_ Excavation.

Macroscopic organisms, 363, 368

Main sewer, defined, 7

Maintenance of sewers, Chap. XII, 332–351
catch-basin cleaning, 343, 344
cleaning sewers, 337–343
complaints, 333
cost, 341
entering sewers, 335, 336
flushing, 109–113, 341–343
hand cleaning, 341
inspection, 333–337
organization, 332
protection of sewers, 344, 345
repairs, 337
tools, 338–341
troubles, 333
work involved, 332

Man, shoveling ability, 243

Manholes, 81, 99–104
bottom, 100
cover, 102–103
drop, 101
flushing, 109, 342
location and numbering, 81
payment methods, 217, 218
steps, 100, 103, 104

Manning’s formula, 55

Map, preliminary, 17, 79, 80, 82, 83

Marsh gas, 347, 366, 367, 410, 415

Marston’s methods for external loads on buried pipe, 198–202

Materials, for sewers, Chap. VIII, 164–193
measurement of, 236, 237
record of, 237
unit weights, 201, 202

McMath’s formula, 47, 48, 94, 95

Meem’s theory of earth pressure, 274, 275

Mercaptan, 367

Metabolism, 365

Methane, 347, 366, 367, 410, 415

Methylene blue, 360

Microscopic organisms, 363, 364, 368

Miles acid process, costs, 487
amount of acid, 483
analyses of sludge, 485
description, 482
results, 483–487
sludge, 485

Mineral matter in sewage, 357

Mirror, inspecting device, 334

Money retained by city, 227

Mosquitoes in catch-basins, 108

Motors, electric, 150–152

Municipal, bond, 14, 15
corporations, 15

_n_, value of in Kutter’s formula, 53

New York City, density of population, 29, 31
siphons under subway, 114
grease and gasoline trap, 108, 109
aëration of sewage, 377, 470
cleaning sewers, 332
depreciation of sewers, 348–351

Needle beam, 286, 287

Night, soil, 5
work, 221

Nitrates, 355, 356

Nitrites, 355, 356

Nitrifying organisms, 431, 432

Nitrobacter, 431, 432

Nitro explosives, 295, 296

Nitrogen, cycle, 367, 368 organic, 355, 356

Nitro-glycerine, 295

Nitrosomonas, 431, 432

Nomograph, 55, 56

Non-uniform flow, 72–77

Nozzles. _See also_ Trickling filters.
coefficients of discharge, 446
types, 445

Numbering, drainage areas, 81, 94
manholes, 81

Nye steam pump, 260, 263

Obstructions to construction, 235

Odor of sewage, 353

Oil in sewage, 108, 344–348

Oiling forms, 174, 186, 322

Olein, 366

Ordinances, for protection of sewers, 344, 345

Organisms in sewage, 363, 364, 368

Organic matter, composition, 366

Organizations for construction, 315, 317, 328

Orders, to whom given, 222

Outfall sewer, defined, 8

Outlets, 99, 122–124, 373

Overflow weir, 118–121
inspection of, 337

Overhead, costs, division of, 10, 237, 238
-track excavators, 246, 250, 251

Oxidation in streams, 373–376

Oxygen, absorption of, 374–377
consumed, 355, 356
demand, 359–361
computation of, 360
bio-chemical, 359–361

Oxygen dissolved
exhaustion of, 366
in dilution, 381
solubility, 362
supersaturation, 361
concentration for successful dilution, 377–380
formulas for concentration, 378–380
significance of in sewage, 359–362

Oysters, contamination of, 372, 489

Packing rings, labyrinth type, 136, 137

Palmatin, 366

Parasites, 365

Paris sewage farm, 460

Patents. Protection of City by contractor, 224, 225

Pathogenic bacteria, 364

Pavement, replacing, 329

Payment, final on contract, 228

Payments, methods of making, 217, 218

Periscope inspecting device, 334, 335

Permissible explosives, 297

Phenolphthalein indicator, 408

Photographic records, 238

Piles for foundations, 123–126

Pills for cleaning sewers, 338

Pipe, bedding, 230, 304, 328
cast-iron. _See_ under cast-iron pipe.
design of ring, Chap. IX, 194–210
external loads on, 198–202
joints. _See_ Joints.
sewer construction, 304–311
laying, line and grade, 282–284
organization, 311
method of laying, 304, 306, 307
steel, design, 195–197
stresses in, external forces, 194, 202–204
stresses due to internal pressure, 194
stresses in buried pipe, 198–204
stresses in circular ring, 202–204
wood design, 197, 198

Plankton, defined, 363
in sewage, 368

Plans, changes in contract, 222, 223

Plug and feathers for splitting rock, 264

Pneumatic, collection system, 5
concreting, 320, 321

Poling boards, in open cut, 271, 272
in tunnel, 287

Pollution, legal features, 380, 381

Population, density, 28–31
predictions, 24–27
served by sewers in the U. S., 3
sources of information, 27, 28
and quantity of sewage, 31, 32

Potter trench machine, 251

Powder. _See_ Blasting.

Power pump, 132, 133

Precautions in entering sewers, 335, 336

Precipitants, chemical, 405–407

Preliminary, map, 17, 79, 80, 82, 83
work, 9, 17–23

Present worth, 158, 160

Pressing sludge, 500, 501

Priming explosives, 302–304

Private, capital, 17
sewers, 17

Privy, 5

Profile, for brick sewers, 312
sewer, 92
surface, 88

Progress, rate of, 222
reports, 238

Promotion (inception of sewers), 9

Proportioning concrete. _See_ Concrete proportioning.

Proposal (contract), 213, 217–219

Protection of sewers (ordinances), 344, 345

Protein, 366

Puddling, backfill, 330

Pulsometer pump, 260, 261

Pumping, in excavations, 256–263
selection of machinery, 154–156
equipment, cost comparison, 162
station, 128, 142
costs, 156–163
equipment, 127, 128

Pumps, air ejector, 150, 151
capacity, 129, 160–163
capacity of units, 160–163
centrifugal, details, 130, 131, 136–138
automatic control, 141, 142
characteristics, 138–140
efficiency, 140
for excavation, 262
motors for driving, 150–152
performance, 138–140
protection of, by screens, 386
selection of, 154–156
setting, 140–142
turbine, 130–132, 154
types, 130, 131

Pumps, centrifugal, volute, 130–132, 154
character of load, 129
costs, 156, 157
description of types, 130–134
for construction work, 256–263
diaphragm, 257, 258
direct-acting, 133
duty of, 135, 136
efficiencies, 135, 136
ejector, 134, 150, 151, 259, 341, 343
jet, 259
need for, 127
number of units, 160–163
packing of, 133, 134
piston, 133
speed, 133, 134
plunger, 133
power, 132, 133
reciprocating, 130, 132–135, 154–156
for excavation, 262
reliability, 127
sizes, 135
steam, 134, 135, 142–146
consumption, 144, 145
vacuum, 259, 262
improvised for trench work, 257
turbine, 130–132, 154
volute, 130–132, 154

Putrescibility, 359, 360

Quantity, of sewage, 24–50, 84–87
variations, 33–38
storm water, 40–50, 94–98

Quicksand, definition, 256
excavation in, 256
safeguards, 235

Quiescent water, self-purification, 374

Racks. _See_ Screens.

Rainfall, 17, 40, 41, 50, 96, 97
data, 17
rate, 96, 97

Rangers, 270–274, 276–279

Rankine’s theory of earth pressure, 275

Rapid sand filtration of sewage, 458

Rational method of run-off determination, 40, 95–98

Reaëration tank in activated sludge, 473

Receiving well, capacity, 129, 130

Reciprocating pumps. _See_ Pumps, reciprocating.

Records, character of, on construction, 238–240

Rectangular sewer section, 67–69

Regulators, 99, 117–121, 337
inspection of, 337

Reinforced concrete sewer design, 209, 210

Reinforcing steel, specifications, 191
placing, 326, 327

Reinsch Wurl screen, 384

Relative stability numbers, 359

Relief sewer, defined, 7

Repairs to sewers, 337

Report, engineer’s preliminary, 10

Reservoir, collecting capacity, 129, 130

Residences, septic tanks for, 416, 417

Residential districts, characteristics, 32–37

Residue on evaporation, 356, 357

Rideal’s dilution formula, 379

Ring, design. Chap. IX, 194–210
stresses in circular, 202–204

River pollution, legal features, 380, 381

Rivers, self-purification of, 373–376

Riveted joints, properties, 196

Rock, blasting, 268, 290, 291
definition, 263
drill, data on, 266, 267
drilling. _See_ also Drilling.
by hand, 264
by power, 264–268
rates, 267
excavation. _See also_ Excavation.
payment for, 230
measurement of, in place, 235
tunnels, 290, 291

Rods, sewer, 338

Roman ordinance relative to sewers, 2

Roofs. _See_ Covers.

Root cutters, 340

Roots, 333, 340

Row lock bond for bricks, 312

Running water, self-purification, 373–376

Run-off, computations, 17, 40, 46–50, 94–98

Safeguards during construction, 221, 241

Salt water, dilution in, 376, 377

Sand, effective size, 456
uniformity coefficient, 456
filters, 452–459
action in, 431, 432, 452–454
control, 458, 506–510
description, 452
dimensions, 456
distribution systems, 433, 456–458
dosing, 454–456
dosing devices, 506–510
materials, 456
operation, 454, 455
preliminary treatment, 455
rate, 455
results, 452, 453
size of sand for, 456
thickness, 456
in winter, 455

Sanitary District of Chicago,
dilution factor, 380
specifications, for manhole covers, 101, 102
tunnel cover, 284
tunnel ventilation, 291

Sanitary engineering, 1, 2

Sanitary sewage, defined, 7, 352

Saph and Schoder’s formula, 54

Saprophytes, 365

Screed, 316

Screens, 383–391
chlorination and fine screens, costs, 487
coarse, 386, 391
data on fine, 388, 389
design of, 389–391
fine, 381, 382, 387–389
fixed, 385, 390
medium, 386
movable, 385, 386, 389–391
moving, 384–386
openings, 386–389
protection to pumps, 127, 141
purpose, 383
results, 386–389
sewage treatment by, 371, 381
size and performance, 386–389
sizes, 386–391
types, 384–386

Screening, vs. sedimentation, 383
purpose, object, 383

Screenings, character of, 386–389

Scum, boards for, septic tanks, 413, 414
Imhoff tanks, 421
chamber in an Imhoff tank, 424
definition, 495

Sediment, velocity of transportation, 396, 397

Sedimentation, 383–405
definition, 383
Hazen’s analysis, 392–395
hydraulic values, 393
a method of treatment, 370
object, 383
Peoria Lakes, 376
protection of siphons, 113, 114
results from plain sedimentation, 401
theory of, 391–395
transportation of debris, 396
velocity of, 392, 393
vs. screening, 383
velocities, limiting, 396, 397

Sedimentation, basins, arrangement, 394
baffling, 404
cleaning, 404
dimensions, 401–403
inlet and outlet, 404
operation, 411
types, 395
chamber, Imhoff tank, 419–422

Self-purification of lakes, 376

Self-purification of streams, 373–376

Separate sewer systems, 78–80

Septic action, 353, 365–368, 371, 410, 411, 496, 497
results, 412, 413
vs. sedimentation, 411

Septic tank, 411
baffling, 413, 414
capacities of small tanks, 417
for country homes, 416, 417
covers for, 415
definition, 411
design, 413–417
explosions in, 415
results, 412, 413
seeding, 413
sludge storage, 414
small, 416, 417
units, 415

Septic sludge analysis, 414

Septicization. Chap. XVI, 410–430
a method of treatment, 371
the process, 410, 411
results, 412, 413

Settling solids, 357

Sewage and water supply, 32
aëration, 371, 376, 465–479
alkalinity of, 358
analyses, chemical, 355, 369, 467
interpretation of, 356–362
physical, 352–354
average, 352–355
bacteria, 362–365
biolysis of, 366, 367
changes in, rate of discharge of, 33–38
characteristics, 368–370
characteristics of, 352–354
chemical constituents, 354–356
classification of, 6, 7, 352
collection, 5
color, 352, 353
components and properties, 352–356
decomposition of, 365–367
definition, 6, 7, 352
disposal. _See also_ Sewage treatment.
methods, 6, 370, 371
purposes, 370, 371
domestic, 7, 352
farming. _See_ Irrigation.
fertilizing value, 459, 460
flow fluctuations, 33–38
ratio of maximum to average, 36, 37, 85
fresh, 352–354
gas, 335, 336, 353
industrial, defined, 7, 352
life in, 363–365, 368
odor, 353
physical, analyses, 352–354
characteristics, 352–354
quality variations, 368–370
quantity. Chap. III, 24–50, and 84, 87
and population, 31, 32
of sanitary, 24–40
variations, 33–38
sanitary, defined, 7, 352
septic, 353, 365–368, 371, 410, 411, 496, 497
stability, 359, 360
stale, 353
storm, defined, 7, 352
strong, 355
temperature, 353
turbidity, 353
treatment processes, 370, 371
A. B. C., 4
activated sludge, Chap. XVIII, 465–479
biological, 371
chemical, 371
contact bed, 432–437, 506
costs, 459
dilution. Chap. XIV, 372–382
disinfection, 489–493
electrolytic, 487–489
filtration, 431–459
increase of, 3
irrigation, 431, 459–464
mechanical, 471
Miles acid process, 482–487
purpose of, 6, 370
résumé, 6, 370, 371
sand filter, 452–458
screening, 383–391
sedimentation, 391–409, 411
septicization. Chap. XVI, 410–430
trickling filters, 437–452
weak, 355
and water supplies, 31, 32

Sewerage, definition, 7
demand for, 2
design, 78–98
growth of, 2–4
historical, 2–4

Sewers, ancient, 2, 3
capacity, diagrams, 56–60
cost, 10–14
definitions of various types, 7, 8
depth of, 88
diameter, 58–60, 88–92
flat grades, 73, 109
flight, 101, 102
inspection of, 333–337
life of, 348–351
location of, 80, 81, 94
materials. Chap. VIII, 164–193
medieval, 3
pipe, properties of concrete, 175
design. Chap. IX, 194–210
vitrified clay, properties, 169–171
profile, 89, 92
section of different types, 67–72
separate system, 78, 79, 82, 86, 87
slope, 88–92
storm-water system, 78, 79, 83, 93, 94
stresses in, 194, 198–204

Shafts, for tunnels, 284–287

Sheeting, 270–280
alignment, 240, 241
backfilling, 330
box, 272
design, 275–280
driving, 273
length, 273
lumber, 277
moving, 248
poling boards, 271, 272, 287
pulling, 274
skeleton, 270, 271
stay bracing, 270
steel, 252, 280, 281
thickness, 276–278
types, 270
vertical, 270, 272–274
Wakefield piling, 273

Shellfish contamination, 372, 489

Shields, tunnel, 288–290

Short loads on trenches, 202

Shovels, for hand excavation, 242
steam. _See_ Steam shovels.

Shovel vane screen, 384

Shoveling by hand, height raised, 244
performance by one man, 243

Symbiosis, definition, 363
example, 432

Sinking fund, 158

Siphons, automatic. Chap. XXI, 506–512. _See also under_ Dosing
devices.
in flush-tanks, 109–110
inspection, 337
operation, 109–110, 506–512
for trickling filter, 448–451
true and inverted, 113–117

Skeleton sheeting, 270, 271

Slope, of sewers, 88–92
of tank bottoms, Imhoff, 419, 423
sedimentation tank, 404

Skewback, 204

Sludge. Chap. XX, 495–505
activated. Chap. XVIII, 465–479. _See also under_ Activated sludge.
analyses, 414, 467, 468, 485, 496
characteristics, 495
definition, 495
digestion tanks, 427–430, 497
disposal methods, 495
drying, 497–505
acid flotation, 503
beds, 498, 500
centrifuge, 501–502
heat, 502, 503
press, 500–501
thickeners, 504, 505
fertilizing value, 470, 495, 497

Sludge, filters, 498–500
lagooning, 495, 496
measurement, 427
press, 500, 501
sedimentation, 401
septic analysis, 434
treatment methods, 495

Soaps, 357

Soil, bearing value, 125
stack, definition, 7

Solids in sewage, 356–368

Special assessment, 15, 16

Specifications. Chap. X, 211–232
general, 219–229
special, 230
technical, 229, 230

Spiling. _See_ Piles.

Spirillum, 362

Spores, 363

Springing line, 204

Sprinkling filter. _See_ Trickling filter

Square sewer section, 68, 69

Stability, relative, 359–361

Stagnant water, 374

Stakes, contractor to provide, 221
where driven, 281, 282

Stationing, 92

Stay bracing, 270

Steam boilers, 147–150

Steam, consumption by, pumps, 144, 145
turbines, 144, 147
engines, 144, 145
pumping engines, 142–146
pumps. _See_ Pumps, steam.
shovels, 246, 252–254
turbines, 146, 147

Stearin, 366

Steel, forms. _See_ Forms, steel.
pipe, 164, 191, 192
design, 195–197
specifications, 191
reinforcement for concrete, 191, 326–327
sheet piling, 252, 280, 281

Stench, historic in London, 4

Sterilization. _See_ Disinfection.

Storm, sewage, definition, 7, 352 Storm, sewer system design, 93–98 water, quantity, 40–50

Storms, extent and intensity, 50

Stream pollution, regulation, 380, 381

Streams, self-purification, 373–376

Street, inlet. _See_ Inlets.
wash, definition, 352

Stresses, in buried pipe, 198–204
in circular ring, 194, 202–204

Sub-main, defined, 7

Subsurface surveys, 18–20

Suction for centrifugal pump, 141

Sulphur and sand joint compound, 309

Sunday work, 221

Surface, elevation, 92
of ground, character, 44–46
profile, 88
water, 7, 352

Surveys, underground, 18–20

Suspended matter, 357

Talbot’s run-off formula, 49

Tamping, backfilling, 328–331

Tannery wastes, disinfection, 491

Taxation, general, 16, 17

Taylor nozzles, 444, 445

Temperature of sewage, 353

Templates, brick sewers, 312

Thawing dynamite, 301, 302

Tide gate, 122

Timbering tunnels, 286–288

Timber, strength of, 277

Time of concentration, 41–43, 95–97

Tools, for cleaning sewers, 337–341
excavating, 242, 246

Tower cableways, 252

Trade wastes. _See_ Industrial wastes.

Traps, in catch-basins, 107
grease, gasoline, and oil, 108, 109
in street inlets, 104, 105

Travis tank, 427, 428

Tree roots, 333, 340

Tremie, 187, 188

Trench, backfilling, 328–331
blasting in, 244, 269
bottom, shape of, 241, 304, 311
breaking surface, 243, 244
drainage, 256–263
excavating, by hand, 242–245
machine, 244–256
guarding and lighting, 221
layout of tasks, 243
length of open, 241, 248
line and grade, 281–284
location, 243, 281
opening, 243, 244
pumps, 256–263
sheeting, 270–280
width, 240, 241, 246

Trestle excavators, 250, 251

Trickling filter, 437–452
advantages, 438, 439
covers for, 451
depth, 441, 442
description, 437, 438
dimensions, 442
distribution of sewage, 442–451
dosing siphon, 446–451
dosing tank, 446–451
head lost, 438
insects, 438
material, 441
nozzles, 442–451
layout, 447–451
odors, 438, 439
operation, 441
rate, 441
results, 439, 440
siphon size, 449–451
underdrainage, 451, 452
unloading, 431, 437

Tripod drill, 265

Triton, 295

Troubles with sewers, causes, 333

Trumpet arch, 121

Trunk sewer, defined, 7

Tunnels, 283–294
backfilling, 331
breast boards, 288
brick invert, 313
compressed air in, 292–294
concrete construction, 320, 321
depth of cover, 284
line and grade in, 283
machines, 290
rock, 290–292
shafts, 284–286
shield, 288–290
timbering, 284–288
ventilation, 291, 292

Turbidity of sewage, 353

Turbine, for cleaning sewers, 340
pumps, 130, 132
steam, 146, 147

Typhoid fever, 364

U-shaped sewer section, 67, 69, 71

Underdrains for, sewers, 126
trickling filters, 451, 452

Underground surveys, 18–20

Unexpected situations, 235

Uniformity coefficient of sand, 456

Unloading of filters, 431, 437

Urea, 367

Valuation of sewers, 332, 348–351

Velocities, depositing, 395–397
distribution of, 51
flow in sewers, 90
over surface of ground, 42
limiting for sedimentation, 396, 397
limiting in sewers, 396, 397
principles of flow in sewers, 51
transporting, 396

Ventilation, air pressures, 291
compressed air, 292–294
pipes, 291

Ventilation, of sewers, 102, 103, 335
tunnel, 291

Vertical sheeting, 270–274

Vitrified clay. _See_ Clay vitrified.

Volatile matter in sewage, 357

Volute pumps, 130, 132, 154

Vouissoir arch analysis, 204

Wakefield piling, 273

Wales, 288

Waste pipe, defined, 7

Wastes. _See_ Industrial wastes.

Water consumption, 31–33
flow of, 51–77
rate of steam engines, 144, 145
supply and sewage flow, 31–33

Watershed. _See_ Drainage area.

Weight, of backfill, 199
of building material, 201
of moving loads, 200, 202

Well, hole, 101
points, 262, 263

Wheel excavator, 246–250

Wing screen, 384

Wood, forms. _See_ Forms.
pipe, materials, 164, 165, 190, 192, 193
design, 197, 198
working strength of, 277

Work, extra, 227
preliminary to design, 9
Sunday, night, and holiday, 221

Workmen, competent, 227
dishonesty, 233, 234

-----

Footnote 1:

Frontinus and the Water Supply of Rome, p. 81, by Clemens Herschel.

Footnote 2:

Estimated by G. W. Fuller, Trans. Am. Society of Civil Engineers, Vol.
44, 1905, p. 148. The total population connected with sewerage systems
was assumed to be the total population in the United States in cities
over 4000 in population.

Footnote 3:

Estimated by Metcalf and Eddy, American Sewerage Practice, Vol. III,
p. 240.

Footnote 4:

Computed from report of the United States Census, 1920, on the same
basis as Fuller’s estimate for 1905.

Footnote 5:

Cosgrove, History of Sanitation.

Footnote 6:

Sedgwick: Sanitary Science and Public Health.

Footnote 7:

No detrimental effect on the public health was noted as a result of
this condition however. It has never been conclusively proven that
such nuisances are detrimental to the public health.

Footnote 8:

Moore and Silcock, Sanitary Engineering, p. 67, 1909.

Footnote 9:

Similar to the definition proposed by the Am. Public Health Assn.

Footnote 10:

Definition recommended by Am. Public Health Assn.

Footnote 11:

Ibid.

Footnote 12:

Ibid.

Footnote 13:

Eng. News, Vol. 76, 1916, p. 781. See also Eng. News-Record, Vol. 85,
1920, pp. 22, 1175.

Footnote 14:

For a more extensive treatment of the subject see Principles and
Methods of Municipal Administration by W. B. Munro, 1916.

Footnote 15:

Eng. Record, Vol. 74, 1916, p. 263.

Footnote 16:

Professional paper No. 46, United States Geological Survey, 1906, p.
97.

Footnote 17:

United States Geological Survey, Water Supply paper No. 257, 1911.

Footnote 18:

From Eng. Cont., Vol. 41, 1914, p. 698.

Footnote 19:

Max. represents only the average maximum, not the greatest maximum.

Footnote 20:

Eng. News-Record, Vol. 80, page 1233, 1918.

Footnote 21:

Infiltration of Ground Water into Sewers. Transactions of the American
Society of Civil Engineers, Vol. 76, 1913, p. 1909.

Footnote 22:

A comprehensive discussion of rainfall formulas will be found in Vol.
54 of the Transactions Am. Society of Civil Engineers, 1905.

Footnote 23:

Formula devised by H. E. Babbitt from Allen’s 25–year curve.

Footnote 24:

See Note under Table 14.

Footnote 25:

Sewerage by A. P. Folwell.

Footnote 26:

From an article by E. Kuichling in Transactions American Society of
Civil Engineers, Vol. 65, 1909, p. 399.

Footnote 27:

Trans. Am. Society Civil Engineers, Vol. 58, 1907, p. 483.

Footnote 28:

Trans. American Society of Civil Engineers, Vol. 58, 1907, p. 498.

Footnote 29:

Ibid.

Footnote 30:

The principles governing the run-off from large areas are explained in
Elements of Hydrology, by A. F. Meyer, 1917.

Footnote 31:

Transactions of the American Society of Civil Engineers, Vol. 51,
1903, p. 11.

Footnote 32:

Municipal and County Engineering, Vol. 58. 1920, p. 164.

Footnote 33:

Industrial waste Treated as ground water.

Footnote 34:

For diagrams for the Solution of the Rational Method, see Eng.
News-Record, Vol. 83, 1919, p. 868 and Vol. 85, 1920, p. 151.

Footnote 35:

Municipal and County Engineering, October, 1909.

Footnote 36:

“Cleaning and Flushing Sewers.” Journal of the Association of
Engineering Societies, Vol. 33, 1904, p. 212.

Footnote 37:

Notes on the Design and Principles of Sewage Siphons, Eng.
News-Record, Vol. 85, 1920, p. 1041.

Footnote 38:

From A. E. Phillips, Trans. Am. Society of Municipal Improvements,
1898, p. 70.

Footnote 39:

Trans. Am. Society of Civil Engineers, Vol. 15, 1886.

Footnote 40:

True Siphon at East Providence, Eng. News-Record, Vol. 85, 1920, p.
862.

Footnote 41:

“The Effect of Mouthpieces on The Flow of Water Through a Submerged
Short Pipe,” by F. B. Seely. Bulletin No. 96, 1917, of the Eng’g.
Experiment Station of the University of Illinois.

Footnote 42:

Trans. Am. Society of Civil Engineers, Vol. 49, 1902.

Footnote 43:

Described by W. L. Stevenson before the Boston Society of Civil
Engineers in 1916.

Footnote 44:

Multiple Outlet for Calumet Intercepting Sewer, by S. T. Smetters,
Eng. News-Record, Vol. 83, 1919, p. 728.

Footnote 45:

“Direct Acting Steam Pumps,” by F. R. Nickel, 1915.

Footnote 46:

From Heat Engines, by Allen and Bursley.

Footnote 47:

“The Economy Resulting from the Use of Variable Speed Induction Motors
for Driving Centrifugal Pumps” by M. L. Enger and W. J. Putnam.
Journal Am. Water Works Ass’n., 1920, Vol. 7, p. 536.

Footnote 48:

C. A. Hague in Trans. Am. Society of Civil Engineers, Vol. 74, 1911,
p. 20.

Footnote 49:

Includes screen chamber, collecting reservoir, and building.

Footnote 50:

Computed on the assumption that the pumps may be operated at 50 per
cent overload for short periods, the rated capacity being equal to the
loads given in Table 33.

Footnote 51:

For description of type see note under Table 35.

Footnote 52:

Proceedings Illinois Society of Engineers, 1916, page 81.

Footnote 53:

Municipal Engineers’ Journal for April, 1918.

Footnote 54:

Workability involves ease in placing and smoothness of working.

Footnote 55:

Johnson’s Materials of Construction, 5th Edition, 1918, p. 432.

Footnote 56:

Trans. Am. Society of Civil Engineers, Vol. 59, 1907, p. 146.

Footnote 57:

L. N. Edwards, Trans. Am. Society Testing Materials, 1918, and R. B.
Young, Eng. News-Record, Vol. 82, 1919, p. 33.

Footnote 58:

Bulletin No. 1, Structural Materials Research Laboratory, Lewis
Institute, Chicago, Illinois.

Footnote 59:

Proportioning Concrete by Voids in the Mortar, A. N. Talbot, read
before Am. Society Testing Materials, June 22, 1921. Abstract in Eng.
News-Record, Vol. 87, 1921, p. 147.

Footnote 60:

Trans. Am. Society of Civil Engineers, Vol. 81, 1917, p. 1122.

Footnote 61:

See also Tentative Specifications for Concrete and Reinforced Concrete
submitted by the Joint Committee to its Constituent Organizations,
June 4, 1921.

Footnote 62:

Journal Illinois Society of Engineers for 1916, p. 75.

Footnote 63:

See A. S. T. M. Standards for 1918, p. 148.

Footnote 64:

Trans. Am. Society Civil Engrs., Vol. 82, 1918, p. 459.

Footnote 65:

See Trans. Am. Society Civil Eng., Vol. 82, 1918, p. 482.

Footnote 66:

See Trans. Am. Society Civil Engr., Vol. 41, 1899, p. 76, and Vol. 82,
1918, p. 433, Eng. News, Vol. 74, 1915, p. 400, and Vol. 75, 1916, p.
911.

Footnote 67:

Trans. Am. Soc. Civil Engrs., Vol. 82, 1918, p. 433.

Footnote 68:

Bulletin No. 31 of the Engineering Experiment Station of the Iowa
State College of Agriculture.

Footnote 69:

From bulletin No. 31, Engineering Experiment Station, Iowa State
College of Agriculture.

Footnote 70:

From Bulletin No. 31, Engineering Experiment Station, Iowa State
College of Agriculture.

Footnote 71:

From Bulletin No. 31, Engineering Experiment Station, Iowa State
College of Agriculture.

Footnote 72:

From Vouissoir Arches by Cain.

Footnote 73:

Baker’s Masonry, 10th Edition, p. 676.

Footnote 74:

Business Law for Engineers, C. Frank Allen, McGraw-Hill, 1917;
Engineering Contracts and Specifications, J. B. Johnson, McGraw-Hill,
1904; Contracts in Engineering, J. I. Tucker, McGraw-Hill, 1910; The
Law Affecting Engineers, W. V. Ball, Archibald Constable, 1909; Law
and Business of Engineering and Contracting, C. E. Fowler,
McGraw-Hill, 1909; The Economics of Contracting, D. J. Hauer, E. H.
Baumgartner, 1915; The Elements of Specification Writing, R. S. Kirby,
John Wiley & Son, 1913; Contracts, Specifications and Engineering
Relations, D. W. Mead, McGraw-Hill, 1916; Engineering and
Architectural Jurisprudence, J. C. Wait, John Wiley, 1912.

Footnote 75:

See article by E. W. Bush in Eng. News-Record, Vol. 85, 1920, p. 122.

Footnote 76:

An unbalanced proposal is one in which the bids on some of the items
are obviously low and on other items are obviously or suspiciously
high. The purpose of submitting unbalanced bids is to keep secret the
true or supposed cost of the work to the contractor or to obtain more
money by bidding high on those items which are believed to have been
underestimated by the Engineer. A low bid is made on other items in
order to keep down the total amount of the bid.

Footnote 77:

Taken mainly from specifications of the Sanitary District of Chicago
and the Baltimore Sewerage Commission, with miscellaneous selections
from other sources.

Footnote 78:

Restrictions are placed on work done outside of ordinary working hours
in order that the Contractor may not perform work in the absence of an
engineer or inspector.

Footnote 79:

Cost Keeping and Management, by Gillette and Dana. Practical Cost
Keeping for Contractors, by F. R. Walker. Cost Keeping in Sewer Work,
by K. O. Guthrie in Eng. Contracting, Vol. 28, p. 238, 1905. Sewer
Construction Records at Scarsdale, Eng. News-Record, Vol. 83, p. 111,
1919.

Footnote 80:

See Planning and Progress on a Big Construction Job, by Chas. Penrose,
Eng. News-Record, Vol. 84, 1920, pp. 554 and 627.

Footnote 81:

See also “Ownership and Operation of Trench Excavators by the Water
Department of Baltimore,” by V. B. Seims, presented before Am. Water
Works Association, June 9, 1921.

Footnote 82:

Eng. and Contracting, Vol. 48, 1917, p. 492.

Footnote 83:

Earth Excavation by A. B. McDaniel.

Footnote 84:

Courtesy, Sanitary District of Chicago.

Footnote 85:

See article by J. R. Gow, Journal New England Waterworks Ass’n, Sept.,
1920, also Public Works, Vol. 50, p. 98.

Footnote 86:

Diameter of diaphragm.

Footnote 87:

Gallons per minute.

Footnote 88:

Eng. News, Vol. 75, 1916 p. 1050.

Footnote 89:

Mun. Engineering, Vol. 53, p. 6.

Footnote 90:

For types of drill bits see article by T. H. Proske, Mining and
Scientific Press, March 5, 1910.

Footnote 91:

These intermediate holes are seldom more than 3 feet apart.

Footnote 92:

Earth Pressures, Old Theories and New Test Results, Eng. News-Record,
Vol. 85, 1920, p. 632.

Footnote 93:

Trans. Am. Society Civil Eng’rs, Vol. 60, 1908.

Footnote 94:

Adopted by the Am. Ry. and Maintenance of Way Ass’n in 1907.

Footnote 95:

Tunneling Machines Successful on Detroit Sewers, Eng. News-Record,
Vol. 84, 1920, p. 329.

Footnote 96:

Rules on Compressed-Air Work of N. Y. State Industrial Commission,
Eng. News-Record, Vol. 85, 1920, p. 1225.

Footnote 97:

Taken mainly from the Engineer Field Manual of the U. S. Army; Safety
Factors in the Use of Explosives by W. O. Snelling, Technical Paper
No. 18, U. S. Bureau of Mines; and an article in Eng’g and
Contracting, Vol. 52, 1919, p. 585.

Footnote 98:

See paper by C. T. Hall before Am. Inst. Chemical Engineers.

Footnote 99:

Per cubic yard of material displaced.

Footnote 100:

Eng. News, Vol. 75, 1916, p. 592.

Footnote 101:

Pressure of Concrete on Forms Measured in Tests, by E. B. Smith,
before Am. Concrete Institute, Feb. 15, 1920. Abstracted in Eng.
News-Record, Vol. 84, 1920, p. 665.

Footnote 102:

See, also, Concrete Form Design, by E. F. Rockwood, Eng. and
Contracting, Vol. 55, 1921, p. 528.

Footnote 103:

Includes 6 cents per foot for excavation. Labor for this was 58 per
cent of the total labor cost.

Footnote 104:

Cement at $1.25 per barrel.

Footnote 105:

Mun. Journal, Vol. 36, 1914, p. 736.

Footnote 106:

Mun. Journal, Vol. 39, 1915, p. 911.

Footnote 107:

Formerly the Municipal Journal.

Footnote 108:

See Eng. Record, Vol. 75, 1917, p. 463.

Footnote 109:

Eng. Record, Vol. 73, 1916, p. 141, and Eng. News-Record, Vol. 79,
1917, p. 1019.

Footnote 110:

Eng. Record, Vol. 72, 1915, p. 690.

Footnote 111:

Eng. Record, Vol. 71, 1915, p. 256.

Footnote 112:

Eng. and Contr., Vol. 41, 1914, p. 250.

Footnote 113:

H. J. Kellogg in Journal Connecticut Society of Civil Engineers, 1914,
and Technical Paper 117, U. S. Bureau of Mines.

Footnote 114:

Eng. News, Vol. 70, 1913, p. 1157.

Footnote 115:

Technical Paper No. 117, U. S. Bureau of Mines.

Footnote 116:

Eng. News, Vol. 71, 1914, p. 84.

Footnote 117:

Eng. News, Vol. 71, 1914, p. 82.

Footnote 118:

Similar to definition proposed by the Am. Public Health Ass’n.

Footnote 119:

Economic Values in Sewage and Sewage Sludge, by Raymond Wells,
Proceedings Am. Society Municipal Improvements, Nov. 12, 1919. Eng.
News-Record, Vol. 83, 1919, p. 948.

Footnote 120:

Sample boiled for five minutes.

Footnote 121:

Sample immersed in boiling water for 30 minutes.

Footnote 122:

Four months.

Footnote 123:

One week in March, 1914.

Footnote 124:

R represents any chemical element such as K, Na, etc.

Footnote 125:

Standard Methods of Water Analysis, American Public Health
Association, 1920.

Footnote 126:

Routine tests are ordinarily incubated for this period only, and if
not decolorized in this time are recorded as stable.

Footnote 127:

Determination of the Biochemical Oxygen Demand of Sewage and
Industrial Wastes, by E. J. Theriault, Report of the U. S. Public
Health Service, Vol. 35, May 7, 1920, No. 19, p. 1087.

Footnote 128:

Standard Methods of Water Analysis, American Public Health
Association, 1920.

Footnote 129:

Jordan, General Bacteriology, 1909, p. 91.

Footnote 130:

Ibid.

Footnote 131:

Reprinted in Vol. III of Contributions from the Sanitary Research
Laboratory of Massachusetts Institute of Technology.

Footnote 132:

Formerly Chief Engineer of the Sanitary District of Chicago.

Footnote 133:

From “Sewage,” by Samuel Rideal, 1900, p. 16.

Footnote 134:

See Am. Civil Engineers’ Pocket Book, Second Edition, p. 982.

Footnote 135:

Trans. Am. Society Civil Engineers, Vol. 58, 1907, p. 988.

Footnote 136:

Not defined by the American Public Health Association.

Footnote 137:

Trans. Am. Society Civil Engineers, Vol. 78, 1915, p. 892.

Footnote 138:

Removal of Suspended Matter by Sewage Screens, Cornell Civil Engineer,
1914. Abstracted in Engineering and Contracting, Vol. 41, 1914, p.
451.

Footnote 139:

“The Clarification of Sewage by Fine Screens,” Trans. Am. Society
Civil Engineers, Vol. 78, 1915, p. 1000.

Footnote 140:

Langdon Pearse, Trans. Am. Society Civil Engineers, Vol. 78, 1915, p.
1000.

Footnote 141:

Meshes per inch.

Footnote 142:

See article by Henry Ryon in Cornell Civil Engineer, 1910.

Footnote 143:

The hydraulic coefficient is defined as the rate of settling in mm.
per second.

Footnote 144:

Definition suggested by the American Public Health Association.

Footnote 145:

Computed from formula by Gilbert in “Transportation of Debris by
Running Water,” U. S. Geological Survey, Professional Paper No. 86,
1914. Diameter in mm. = (1.28 (velocity)^{2.7})⁄(Sp. gv. − 1).

Footnote 146:

Computed from Annual Report of the Superintendent of Sewers, Nov. 30,
1919, and 1920.

Footnote 147:

These figures are for 1919.

Footnote 148:

These figures are for 1905.

Footnote 149:

These figures are for 1902.

Footnote 150:

Report of the Ohio State Board of Health, 1908, page 425.

Footnote 151:

Definition proposed by the Am. Public Health Assn.

Footnote 152:

See Eng. News. Vol. 73, 1915, p. 410.

Footnote 153:

Sewage Treatment from Single Houses and Small Communities, by L. C.
Frank. U. S. Public Health Service, Bulletin 101, 1920.

Footnote 154:

Eng. News-Record, Vol. 78, 1917, p. 566.

Footnote 155:

Municipal Engineering, Vol. 54, p. 149.

Footnote 156:

Eng. Record, Vol. 68, 1913, p. 452.

Footnote 157:

Am. Sewerage Practice, Vol. III, p. 437.

Footnote 158:

Trans. Am. Society Civil Engineers, Vol. 83, 1920, p. 337.

Footnote 159:

Eng. News-Record, Vol. 83, 1919, p. 510.

Footnote 160:

See Eng. News, Vol. 70, 1913, p. 1112; Eng. Record, Vol. 68, 1913, p.
440, and Eng. News, Vol. 75, 1916, p. 1028.

Footnote 161:

See Eng. Record, Vol. 67, 1913, p. 232.

Footnote 162:

The use of half-spray nozzles is not always advocated as it is
considered that their use does not markedly improve the distribution.
Where half nozzles are used, a margin of 18 inches to 2 feet should be
allowed between the edge of the filter and the nozzle, to prevent the
blowing of raw sewage from the filter.

Footnote 163:

From paper by E. G. Bradbury in Proceedings of the Ohio Eng. Society,
1910, p. 79.

Footnote 164:

The effective size of sand is the diameter in millimeters of the
largest grain in that 10 per cent, by weight, of the material which
contains the smallest grains.

Footnote 165:

The uniformity coefficient is the ratio of the diameter of the largest
particle of the smallest 60 per cent, by weight, to the effective
size.

Footnote 166:

Interest at 6 per cent.

Footnote 167:

Worcester figures.

Footnote 168:

This method may show a profit from the sale of sludge.

Footnote 169:

Sewage Disposal, 1919, p. 223.

Footnote 170:

See Eng. News, Vol. 9, 1883, p. 203, and Vol. 29, 1893, p. 27.

Footnote 171:

American Sewerage Practice, Vol. III.

Footnote 172:

Reference 11, at end of this chapter.

Footnote 173:

Reference 15.

Footnote 174:

Reference 2.

Footnote 175:

For mechanical methods of drying sludge, see Reference 22, p. 1127,
and No. 33, p. 843.

Footnote 176:

Reference 10.

Footnote 177:

Reference 13.

Footnote 178:

University of California, Bulletin 251, 1915.

Footnote 179:

Reference 25.

Footnote 180:

See Report by Black & Phelps of Metropolitan Sewerage Commission,
1911, reprinted as Vol. VII of Contributions from the Sanitary
Research Laboratory of the Massachusetts Institute of Technology.

Footnote 181:

See Reports, Mass. State Board of Health.

Footnote 182:

Reference 47.

Footnote 183:

Reference 10.

Footnote 184:

Reference 10.

Footnote 185:

Reference 10.

Footnote 186:

Hatton, reference 33.

Footnote 187:

Reference 18.

Footnote 188:

Reference 1, at end of this chapter.

Footnote 189:

Reference 2.

Footnote 190:

Reference 6.

Footnote 191:

Reference 5.

Footnote 192:

Reference 6.

Footnote 193:

Reference 6.

Footnote 194:

Reference 8.

Footnote 195:

Reference 20.

Footnote 196:

Reference 17.

Footnote 197:

Reference 19.

Footnote 198:

Reference 21.

Footnote 199:

Reference 24.

Footnote 200:

Inorganic Chemistry, by Alexander Smith.

Footnote 201:

American Public Health Association definition.

Footnote 202:

Sewage Sludge by Allen.

Footnote 203:

Sewage Disposal by Kinnicutt, Winslow and Pratt.

Footnote 204:

Sewage Disposal by Fuller.

Footnote 205:

Sewage Sludge by Allen.

Footnote 206:

From Eng. News-Record, Vol. 84, 1920, p. 995.

Footnote 207:

A Simple Mechanical Control for Dosing Sewage Beds, by P. Thompson,
Eng. News-Record, Vol. 84, 1920, p. 1018.

Footnote 208:

Sewage Disposal by Kinnicutt, Winslow and Pratt.

Footnote 209:

Design of Siphon by G. H. Bayles, Eng. News-Record, Vol. 84, 1920, p.
974.

------------------------------------------------------------------------

TRANSCRIBER’S NOTES

1. Silently corrected typographical errors and variations in spelling. 2. Archaic, non-standard, and uncertain spellings retained as printed. 3. Enclosed italics font in _underscores_. 4. Enclosed bold font in =equals=. 5. Superscripts are denoted by a caret before a single superscript character or a series of superscripted characters enclosed in curly braces, e.g. M^r. or M^{ister}. 6. Subscripts are denoted by an underscore before a series of subscripted characters enclosed in curly braces, e.g. H_{2}O.