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should be placed upon them as a means of purifying sewage, the
fatal defects being constant, saturation with sewage and lack of air
supply. To the extent that the submerged outlets keep back grease
and solid matters the scheme is of service in preventing clogging
of the pores of the surrounding ground.

Where the ground about a cesspool has become clogged and water-
logged, relief is often secured by laying several lines of drain
tile at shallow depth, radiating from the cesspool. The ends of the
pipes within the cesspool should turn down, and it is advantageous
to surround the lines of pipe with stones or coarse gravel, as shown
in figures IT and 18 and discussed under " Septic tanks/' In this
way not only is the area of percolation extended, but" aeration and
partial purification of the sewage are effected.

Where a cesspool is located at a distance from a dwelling and
there is opportunity to lead a vent pipe up the' side of a shed, barn,
or any stable object it is advisable to do so for purposes of ven-
tilation. Where the conditions are less favorable it may be best,
because of the odor, to omit any direct vent pipe from the cesspool
and rely for ventilation on the house sewer and main soil stack ex-
tending above the roof of the house.

Cesspools should be emptied and cleaned at least once a year and
the contents given safe burial or. with the requisite permission,
wasted in some municipal sewerage system. After cleaning, the
walls and bottom may be treated with a disinfectant or a deodorant.

SEPTIC TANKS.

A tight, underground septic tank with shallow distribution of the
effluent in porous soil generally is the safest and least troublesome
method of treating sewage upon the farm, while at the same time
more or less of the irrigating and manurial value of the sewage may
be realized.

The late Prof. Kinnicutt used to say that a septic tank is " simply
a cesspool, regulated and controlled." The reactions described under
the captions " How sewage decomposes," " Liquefying closet," and
" Cesspools" take place in septic tanks.



Sewage and Sewerage of Farm Homes. 29

In all sewage tanks, whatever their size and shape, a portion of
the solid matter, especially if the sewage contains much grease, floats
as scum on the liquid, the heavier solids settle to form sludge, while
finely divided solids and matter in a state of emulsion are held in
suspension. If the sludge is retained in the bottom of the tank and
converted or partly converted into liquids and gases the tank is called
a septic tank and the process is known as septicization. The process
is sometimes spoken of as one of digestion or rotting.

History. Prototypes of the septic tank were known in Europe
nearly 50 years ago. Between 1876 and 1893 a number of closed tanks
with submerged inlets and outlets embodying the principle of storage
of sewage and liquefaction of the solids were built in the United States
and Canada. It was later seen that many of the early claims for the
septic process were extravagant. In recent years septic tanks have
been used mainly in small installations, or, where employed in large
installations, the form has been modified to secure digestion of the
sludge in a separate compartment, thus in a measure obviating dis-
advantages that exist where septicization takes place in the presence
of the entering fresh sewage.

Purposes. The purposes of a septic tank are to receive all the farm
sewage, as defined on page 4, hold it in a quiet state for a time,
thus causing partial settlement of the solids, and by nature's proc-
esses of decomposition insure, as fully as may be, the destruction of
the organic matter.

Limitations. That a septic tank is a complete method of sewage
treatment is a widespread but wrong impression. A septic tank
does not eliminate odor and does not destroy all organic solids. On
the contrary, foul odors develop, and of all the suspended matter in
the sewage about one-third escapes with the effluent, about one-third
remains in the tank, and about one-third only is destroyed or reduced
to liquids and gases. The effluent is foul and dangerous. It may con-
tain even more bacteria than the raw sewage, since the process in-
volves intensive growths. As to the effects upon the growth and viru-
lence of disease germs little is known definitely. It is not believed
that such germs multiply under the conditions prevailing in a septic
tank. If disease germs are present many of their number along with
other bacteria may pass through with the flow or may be enmeshed
in the settling solids and there survive a long time. Hence the farmer
should safeguard wells and springs from the seepage or discharges
from a septic tank as carefully as from those of liquefying closets
and cesspools.

Further treatment of effluents. The effluent of a septic tank or any
other form of sewage tank is foul and dangerous. Whether or not
the solids are removed by screening, by short periods of rest, as in
plain or modified forms of settling tanks, or by longer quiescence,



30 Farmers Bulletin 1227.

as in septic tanks, .the effluent generally requires further treatment
to reduce the number of harmful organisms and the liability of
nuisance. This further treatment usually consists of some mode of
filtration. In the earliest example of such treatment the sewage
was used to irrigate land by either broad flooding or furrow irriga-
tion. By another method the sewage, is distributed underground by
means of drain tile laid with open joints, as illustrated in figures
17, 29, and 32.

Artificial sewage filters are composed of coarse sand, screened
gravel, broken stone, coke, or other material, and the sewage is
applied in numerous ways. Since filtration is essentially an oxidiz-
ing process requiring air, the sewage is applied intermittently in
doses. 9

If properly designed and operated, filters of sand, coke, or stone
are capable of excellent results. Under the most favorable condi-
tions it is unwise to discharge the effluent of a sewage filter in the
near vicinity of a source of water supply. Under farm conditions
filters are usually neglected or the sewage is improperly applied,
resulting in the clogging and befouling of sand filters and the dis-
charge from stone filters of an effluent which is practically as danger-
ous and even more offensive than raw sewage. Moreover unless the
filters are covered there are likely to be annoying odors, 'and there
is always the possibility of disease germs being carried by flies where
sewage is exposed in the vicinity of dwellings. Hence it seems more
practical for the farmer, avoiding the expense of earth embankments
or masonry sides and bottom for a filter bed, to waste the tank
effluent beneath the surface of such area of land as is most suitable
and available. This method of applying sewage to the soil or sub-
soil is often spoken of as subirrigation. but subsoil distribution of
sewage is different in principle and practice from subirrigation for
the increase of crop yields. Subirrigation is rarely successful unless
the land is nearly level, the top soil porous and underlaid with an
impervious stratum to hold the water within reach of plant roots,
and unless a relatively large quantity of water is used and -the work
is skillfully done. On the other hand, the quantity of sewage on
farms being small, it may be wasted in hilly ground, which should be
as porous, deeply drained, and dry as possible.

Parts of a system. The four parts of a septic-tank installation with
subsurface distribution of the effluent are outlined in figure 19: (1)
The house sewer from house to tank; (2) the sewage tank consisting
of one or more chambers; (3) the sewer from tank to distribution

9 Artificial filters of various types are well described and illustrated in Public Health
Bulletin No. 101. " Studies of Methods for the Treatment and Disposal of Sewage The
Treatment of Sewage from Single Houses and Small Communities." U. S. Public Health
Service. December, 1919.



Sewage and Sewerage of Farm Homes.



31



field; (4) the distribution field, where the sewage is distributed and
wasted, sometimes called the absorption field. These parts will be
discussed in the order named, although the last should have the first
consideration.

House sewer. The length will vary with the slope of the ground
and position of buildings, well, and distribution field. Fifty to 100



Distribution Tile



House



TankT



Under drain
(if necessary)



. - J Drainage

in-r



Outlet



1051




FIG. 19. Parts of a septic-tank installation.

feet is a fair length ; a greater is still more sanitary. Wherever pos-
sible the house sewer should be laid straight in line and grade. Fig-
ure 20 shows how this work may be done. Suppose the distance from
A to E be 100 feet ; that grade boards be set 25 feet apart crosswise
of the trench at A, B, C, D, and E; that the ground at A be 4 feet
lower than at E ; that the top of the sewer be 2| feet below the surface



B




I3&I

PIG. 20. Setting line and grade for house sewer. To the observer at A the top edges
of the grade boards appear as one ; the half-driven nails are set to line.

of the ground at A and 4| feet below the surface of the ground at E ;
the fall of the sewer between A and E is 2 feet (4+2^ 4J=:2). If
the fall in 100 feet be 2 feet, in 25 feet it is one-fourth as much, or 6
inches. Hence, grade board B is 6 inches higher than grade board
A, C is (? inches higher than B, and so on to E. The top edges when
all the boards are set with a carpenter's level and fastened in position
should be in line. The grade thus established may be any con-



32 Farmers' Bulletin 1227.

venient height above the top of the proposed sewer, and the measur-
ing stick used to grade the pipe is cut accordingly. This height is
usually a certain number of whole feet. Fixing the line of the sewer
is a mere matter of settling nails in the top edges of boards A and E
directly over the center of the proposed sewer and tightly stretching
a fish line or grade cord; nails should be set where the cord crosses
boards B, C, and D.

If the cellar or basement contains plumbing fixtures, the house
sewer should enter 1 to 2 feet below the cellar floor. If all plumbing
fixtures are (5n the floors above, the sewer may enter at no greater
depth than necessary to insure protection from frost outside the cel-
lar wall. Digging the trench and laying the pipe should begin at the
tank or lower end. The large end of the pipes, called the hub, should
face uphill, and the barrel of each pipe should have even bearing
throughout its length. Sufficient earth should be removed from be-
neath the hubs to permit the joints to be made in a workmanlike
manner.

The house sewer may be vitrified salt-glazed sewer pipe, con-
crete pipe, or cast-iron soil pipe. The latter, with poured and calked
lead joints makes a permanently water-tight and root-proof sewer,
which always should be used where the vicinity of a well must be
passed ; 4, 5, or 6-inch pipe may be used, depending mainly on the fall
and in less degree on the quantity of sewage discharged. As a meas-
ure of economy the 4-inch size is favored for iron pipe. If vitrified
pipe is used, either the 5 or 6 inch size is preferable, as these sizes are
made straighter than the 4-inch size and are less liable to obstruction.
Of the two the 5-inch size is preferable. The fall in 100 feet should
never be less than 2 feet for 4-inch size, H feet for 5-inch size,
1 foot for 6-irich size.

Figure 21 shows methods of making good joints. A, B, G, D, E,
F, and G are ordinary sewer pipe joints; H, is cast-iron soil pipe.

A shows the use of a yarning iron to pack a small strand of jute into the
joint space, thus centering the pipes and preventing the joint filler running inside.
The joint surfaces should be free of dirt and oil. The jute is cut in lengths to
go around the pipe ; a small strand is soaked in neat Portland cement grout, then
twisted and wrapped around the .small end of the pipe to he pushed into the
hub of the last pipe laid. After the pipe is pushed home the jute is packed
evenly to a depth of not over \ inch, leaving about 14 inches for the joint filler.
Old hemp rope or oakum dipped in liquid cement or paper may be used in place
of jute, and the packing may be done with a thin file or piece of wood.

fi shows the use of a rubber mitten or glove to force Portland cement mortar
into the joint space. The mortar should be thoroughly and freshly mixed in the
proportion of one volume of cement to one volume of clean sand and should be
pressed and tamped to fill the joint completely.

C shows a section of finished joint. The fresh mortar should not be loosened
or disturbed when laying the next pipe.

D shows method of pouring a joint with grout, which is quicker, cheaper, and
better than using a rubber mitten. A flexible sheet-metal form or mold, oiled
to prevent the grout sticking, is clamped tightly around the joint and is com-
pletely filled with grout consisting of equal parts of Portland cement and clean



Sewage and Seweraae of Farm Homes. 33

sand mixed dry, to which water is added to produce a creamy consistency. The
pipes should not be disturbed and the form Khould not be removed for 24 hours.

/; shows a section of grouted joint, well rounded out, strong, and tight.

F shows the use of a pipe jointer for pouring a hot filler. The pipe jointer
may be an asbestos or rubber runner or collar or a piece, of garden hose clamped
around the pipe leaving a small triangular opening at the top. The jointer is
pressed firmly against the hub, and any small openings between the jointer and
pipe are smeared with plastic clay to prevent leakage of the tiller. A clay dike
or funnel about 3 inches high built around the triangular opening greatly aids
rapid and complete filling of the joint space. The filler may be a commercially
prepared bituminous compound or molten sulphur and fine sand. The former
makes a slightly elastic joint; the latter a hard unyielding joint. With good
workmanship both kinds of joint are practically water-tight and root-proof,
and cost about the same as cement mortar joints. The filler is heated in an iron
kettle over a wood, coke, or coal fire. It should be well stirred, and when at a
free running consistency should be poured with a ladle large enough to fill the
joint completely at one operation. As soon as the compound cools the jointer
is removed. Sulphur-sand filler is made by mixijig together dry and melting
equal volumes of ordinary powdered sulphur and very fine clean sand, pre-
lerahly the finest quicksand. A .~>-incli sewer pipe joint requires from three-tenths
to nine-tenths of a pound (according to the kind of pipe) of sulphur, worth 3 to
T) cents per pound, and a like quantity of sand. From to 1 pounds of bitu-
minous filler are required for a 5-inch pipe joint.

G shows section of finished joint.

H shows the use of a pouring ladle in making lead joints in cast-iron soil pipe.
This pipe is in lengths to lay 5 feet, and the metal of the barrel is inch thick.
The joint is yarned with dry jute or oakum, as described above, and is poured
full with molten, soft, pig lead to be afterwards driven tightly with hammer and
calking tools. About 1 pound of lead for each inch in diameter of pipe is
required. Prepared cements of varying composition have proved effective and,
as they require no calking, are economical. Among the best is a finely ground,
thoroughly mixed compound of iron, sulphur, slag, and salt.

/ is a homemade pipe jointer or clay roll for use in pouring molten lead. A
strand of jute long enough to encircle the pipe and the ends to fold back, leaving
an opening at the top, is covered with clay m< listened, rolled, and worked to form
a plastic rope about 1 inch in diameter. The jointer gives the very best results
but must be frequently moistened and worked to keep the clay soft and pliable.
The jointer shown in F is frequently used for pouring lead joints.

Obstructions in house sewers are frequent. Among the causes
are broken pipes, grade insufficient to give cleansing velocities, news-
paper, rags, garbage, or other solids in the sewage, congealing of
grease in pipes and main running traps (house sewer traps), and
poor joint construction whereby rootlets grow into the sewer and
choke it. Good grade and good construction, with particular care
given to the joints, will avert or lessen these troubles. The sewer
should be perfectly straight, with the interior of the joints scraped
or swabbed smooth. When the joint-filling material has set, the
hollows beneath the hubs should be filled with good earth free of
stones, well tamped or puddled in place. It is important that like
material be used at the sides of the pipe and above it for at least
1 foot. The back filling may be completed with scraper or plow.
No running trap should be placed on the house sewer, because it
is liable to become obstructed and it prevents free movement of air
through the sewer and soil stack. Conductors or drains for rain
or other clean water should never connect with the house sewer,
but should discharge into a watercourse or other outlet.



34



Farmers Bulletin 1227.



Where obstruction of a house sewer occurs, use of some of the

simple tools shown in figure 22 may remedy the trouble. It is not

likely that farmers will have these appliances, except possibly some

of the augers; but some of them can be made at home or by a black -

\ smith, and most of



Jute



\




B




c

Cem ent mortar -



Jute




Grout after setting.



Jute




jointing
compound^




I

Strand of jute



Plastic clay



1308



them should be ob-
tainable for tempo-
ran; use from a well-
organized town or
city sewer depart-
ment. The purpose of
the several tools
shown is indicated in
the notation.

The tank.. The
septic tank should be
in an isolated location
at least 50 to 100 feet
from any dwelling.
This is not always
possible, because of
flat ground, but in
many such instances
reasonable distance
and fall may be se-
cured by raising both
the house sewer and
tank and embanking
them with earth.
Cases are known
where tanks adjoin
ce 1 1 a r or basement
walls and the top of
the tank is used as a
doorstep ; in other
cases tanks have been
constructed within
buildings. Such prac-
tices are bad. It is



FIG. 21. How to make good joints. See text for direo-
tions and specifications.

difficulty to construct an absolutely water-tight masonry tank, and
still more difficult to make it proof against the passage of sewage odors.
In Northern States, particularly in exposed situations, it is de-
sirable to have the top of the tank 1 to 2 feet underground, thus
promoting warmth and uniformity of temperature in the sewage.



Sewage and Sewerage of Farm Homes.



35



In Southern States this feature is less important, and the top of the
tank may be flush with the ground. Every tank should be tightly
covered, for the reason above stated and to guard against the spread

B D



-LJ-





<T < C




H



or>




LLLLLLUJ



M



1305




K



FIG. 22. Sewer-cleaning tools how to use them. A, Ordinary 1| or 2 Inch auger
welded to a piece of 2 -inch extra-strong wrought pipe about 5 feet long ; the stem Is
lengthened by adding other pieces of pipe with screw couplings, and is fitted with a
pipe handle; all cleaning work should proceed upstream ; B, twist or open earth auger ;
C, ribbon or closed earth auger ; D, spiral or coal auger ; E, ship auger ; F, root cutter ;
<?, sewer rods with hook coupling, usually of hickory or ash 1 or 1| inches in diameter
and 3 or 4 feet long ; //, gouge for cutting obstructions ; /, scoop for removing sand or
similar material ; J, claw, and K, screw, for removing paper or rags; L, scraper;
M, wire brush for removing grease, drawn back and forth with a wire or rope ; N,
home-made wire brush (for a 5-inch sewer use a 1 i-inch wooden pole to which is
securely tacked a piece of heavy rubber, canvas or leather belting or harness leather
5i by 8 inches, spirally studded, as shown, with ordinary wire nails 1| inches in
length).

of odors, the transmission of disease germs by flies, and accidents to
children.

Considerable latitude is allowable in the design and construction
of septic tanks. No particular shape or exact dimensions can be
presented for a given number of people. One family of 5 persons



Fanners' Ilnllctin 1227.



may use as much water as another family of 10 persons; hence ihe
quantity of sewage rather than the number of persons is the better
basis of design. Exact dimensions are not requisite, for settlement
and septicization proceed whether the sewage is held a few hours
more or a few hours less. As to materials of construction some form
of masonry, either brick, building tile, rubble, concrete, or cement
block, is employed generally. Vitrified pipe, steel, and wood have
been used occasionally.

A plant for use all year round should have two chambers, one to
secure settlement and septicization of the solids and the other to
secure periodic discharge of the effluent by the use of an automatic
sewage siphon. The first chamber is known as the settling chamber,
the second as the siphon or dosing chamber. The siphon chamber is
often omitted and the effluent is allowed to dribble away through sub-
surface tile, as illustrated in figures IT and LS. The latter procedure
is not generally advised, but may be permissible where the land
slopes sharply or has long periods of rest, as at summer houses and
camps.

The septic tanks shown in this bulletin are designed to satisfy
the following conditions :

1. Water consumption of 40 gallons per person per day of 24
hours.

2. A detention period of about 24 hours ; that is, the capacity of the
settling chamber below the flow line is approximately equal to the

quanity of sewage
discharged from the

Double plank cover > __ , C\A i

house in 24 hours.
3. Where a si-
phon chamber is
provided, its size is
such that the close of
sewage shall be ap-
proximately equal
to 20 gallons per
person; that is, the
capacity qf the si-
phon chamber be-
tween the discharge
and low-water lines

FIG. 23. One-chamber septic tankdoes nothing more ^ rou g^l> T equal to

than a tight cesspool. Brick construction, heavily plas- the quantity OT SCW-

tered inside; size suitable for 180 to 280 gallons of age discharged in

sewage daily (nominally 4 to 7 persons). |2 hours

A simple one-chamber brick tank suitable for a household discharg-
ing 180 to 280 gallons of sewage daily is shown in figure 23. A
small two-chamber tank constructed of 24-inch vitrified pipe, suitable
for a household discharging about 125 gallons of sewage daily, is
shown in figure 24. A typical two-chamber concrete tank is shown in
figure 25. Excepting the submerged outlet, all pipes within the tank



to distribution
trenches



Port/and cement
p/asfer coat

4'-0"
2' wide inside




Submerged
otft/et



Sewage and Sewerage of Farm Homes.



37



and built into the masonry are cast-iron soil pipe with cast-iron fit-
tings. Vitrified or concrete sewer pipe and specials are generally
used as they are frequently more readily obtainable and a slight
saving in first cost may be effected. Cast iron is less liable to be
broken in handling or after being set rigidly in masonry, and the
joints are more easily made water-tight. The submerged outlet is
midway of the depth of liquid in the settling chamber. The inside
depth of the siphon chamber is the drawing depth of the siphon
plus 1 foot 5 inches.

The, following table gives the principal dimensions with quantities
of materials for four sizes of tank as illustrated in figure 25 :

Dimension* and quantities for .vr/;//r lunkx.



Settling chamber.



Number of persons. I %^ y

' age in
24 hours.


Capacity
below
flow line.


Length.


Depth.


1

Width. W. X.

i
1


Y.


Z.


GaMs.
5 180-280


Galls.
240


Ft. In.
4


Ft. In.
5


Ft. In. In. Ft. In.
20 6 20


In.

4


In.
6


10 320-480


420


5


."> 6


26 6 23


4


6


15 520-680
20 720-960


620
860


5 6
6


6

6 6


30 8 26
3 6 8 29


5
5


8
8

















Num-
ber
of
per-
sons.


Quan-
tity of
sewage
in 24
hours.


Siphon chamber.


Con-
crete.


Ce-
ment


Sand.


Stogie.


Reinforcement
in top slab
(strip of heavy
stock fencing).


Length.


Depth.


Width.


A.

In.
3
3
4
4


B.


c.

In.
15
15
17
17


D.

In.
18*
18}
20}
20|


Length.


Width.


5
10....
15....
20....


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Online LibraryGeorge M. (George Milton) WarrenSewage and sewerage of farm homes → online text (page 3 of 5)