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1150 (6)
MAKING CONCRETE SEPTIC TANKS
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. H .xiudSiVE FARMER
fQpenjbnted Tite
Description of a Sanitary Method of Sewage Disposal Where the
Advantages of a Modern City of Town Sewerage System Are Not
Available . . - - ,- - ,-
AS THERE must be some way of disposed of to prevent them from
disposing of the house wastes - being Vpossiblejource of disease.
a a from tne dwelling equippeu .. uauuiy wwuuvu, vr.w
with modern plumbing appointments, tank is built in two. compartments, as
where a town or city sewerage sys- shown in Figure 1. Slight modifica-
tem is not available, the septic tank tions of this design are often made,
has been developed, as an approved none'of which, however, departs from
means of meeting requirements un- the fundamental principles shown,
der certain conditions. ' . The house, wastes after they leave
In disposing of sewage from a the house plumbing, enter the first
dwelling that cannot be connected compartment. In this compartment
with a city sewerage system there the action of the bacteria spoken of
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' TlgtLM 2. 4 This plan UluBtrateg the layout of a septic tunlr .
.. necessary tUa lines -when the final dlaposal tystem la planned for XtStiSfrJ
The aketch at "A ahow8n method whichl5mettoe8P S
In laying tile where the soil is dense, like clay or gumbo. """y to use
forms in this tank after it is in ef- about 6 feet apart and with sufficient
iective - operaiiun.; iai5 stum iuusi giauc su inai ine nuias will quickly
not be disturbed nor be allowed and easily spread over the whole
to- flow out of this compartment, area, lhis will prevent the soil at
i Round rodiictocTJbdow
p o floor .
on
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because it is the home of the
bacteria which : do the first work to
wards changing the nature of the
sewage: namely, destroying the solid field had to receive and dispose of all
and semi-solid substances which are the tank discharges. Where the vol
carried into the tank along' with the ume of sewage exceeds a certain
liquids. '
Two methods are commonly, de
pended upon to dispose of the dis
charges from the siphon chamber, re
sulting from the- frequent emptying
of this compartment due to the auto
matic operation of the siphon. Wher
ever the nature of the surroundings which is "frequently practiced con
is such that a certain area of ground sists of what is called subsurface ir-
1
that portion of the field near the
outlet trom becoming clogged up, as
would happen if a small area of the
quantity, that is, more than results
from the average household, it is
sometimes advisable to arrange for
two disposal fields that can be used
alternately, ; thus allowing one to
"rest" at intervals.
Another method of final disposal
J f - A
Figure 1. Longitudinal and cross-sectional views, also plan of an efficient type of septic tank. The upper
left-hand view shows the tank as it would appear if cut away at its center along a line following Its length.
To the right of thiBTlew is .a section of the siphon chamber ,
are several problems to be taken takes place and the solids and semi--
into consideration. House wastes solids are digested, so to speak, by
consist of a combination of liquid this bacterial action.
and solid or semi-solid matter, and The second compartment is fre-
the solids must in some way be "di- quently referred to as the "siphon
gested" or separated from the liquid chamber.". It will be noticed that
matter. After this has been done,7 there is a device built into the floor
proper arrangements must be made of this compartment and connected,
to dispose of the liquids.
. Experience has proved that the
solid matter in ordinary domes-
tic sewage win, it connned in a
to an outlet pipe. This device is call
ed a siphon and automatically emp
ties the contents of the compartment
when they have reached a certain
suitable compartment, practically air- level by overflow from the first com- -DIO
tight and away from light, undergo partment. These siphons are not ex-
a rotting or decomposition as a re- pensive and can be obtained from
any one of a number of firms.
After; having remained in the first
ra - ... . . rrb.ljl...w,Mtig -u-r-
dill R i: III! I , S . 22 22221' S22f-
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77iS ecnsfrvction at
ttmrtrtgbttJitt
erafir ,secrONAL plan
figure 4. Two sectknal vlew plan" and alternattTe filter Jloo? tat type cl tank that fa
where final disposal by broad Irrigation must be practiced. This riew shows the t Mit sway awm
- a Hue followtog its length at the center and a similar sectional flew o .the filter compartment.
can be set aside for the purpose, W- rigation. This means discharging the
face, or broad irrigation, as it is call- tank contents into lines of (our-incn
ed, is satisfactory. This means allow- drain tile, laid with open Jojmmo
ing the wastes deHvered from the that; fluids may leach out ot tnese
siphon compartment to flow upon the joints and filter into and twougn we
land where they spread over .the soil. : Such' a tile line should be . law
itU i err A tint creater than & mcn-
and certain bacteria which live in the es per 100 feet. To prevent soil trom
. r . !ia tli rmi ph open
upper Uyers or portion of the soil entering the tile line wrougu
In the final disposal of sewage by joints, and tnus-cioggmg h
brnad irricratinn: if is nf mtirso nPS. iftints mav be Covered Wltn
x -u j: i i i...,;'...!., nf broken tile oi
as it is sometime called, where the larger diameter. All connections w
wastes will not be immediately wash- tween; the house and septic tame
ed into some nearby stream, thus from the septic tank to the aisp
contaminating the water. Fluids: thus field should be made with tight jou . .
disposed of should be carried to the This means that m the subsuri at
disposal field through a tile line'lead- disposal system there should i oe
ing from the siphon connection, these least 200 feet of tile laid trom i
tile being dense, non-porous and laid siphon chamber before the open-
-with sealed joints." The outlet should laterals are laid." , ,.ffle
discharge into an open ditch, - say. Figure 2 shows the general sen
about 12 inches wide by 6 inches of laying tile lines where suu"
deep; with laterals pr side pitches at disposals employed. As a i ru
right angles to the main one, dug 1 (Concluded on pags 22, this
Cover"
Figure I. combined section il and perspective tiew
of the tank Illustrated la Figure 1.
Cover
"suit of the development of certain compartment a sufficient length of fXfPf
bacteria which might be referred to time the solid matter which the
as Nature's scavengers, ihese bacte- wastes contained upon entering this
ria feed, so to speak, upon the solids compartment has been destroyed, and
. and- semi-solids in the sewage, thus the liquids overflow into the second
'-. converting them into gas send rela- compartment or siphon chamber. ,
lively harmless compounds It must It will be noticed in the design
not be understood, bowever, that this , shown in Figure 1 that the first com
action is by any means likely to de- partment contains two baffle boards
stroy disease -germs that may be extending in part above and below
' present, since the processes; taking the level of liquid in this compart
vplace .in the septic -tank are inot ment. These are necessary to pre-'
chemical ones and the discharges af- . vent tne rush of incoming sewage,
ttife 'Wakincr down" process of from the house olumbinor svstem
: ;r the , sewage Atnust tiU ,be properly from disturbing the , scum which - a SToiV
l&ntildtor..
u.X - Cover" 1V
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Reinforcing
Figure
A combined sectional and nersnectlra
detau the construction of the
tank illustrated in Figure4.