Where farms have water under pressure an open or leaching cesspool is a
common method of disposing of the sewage. Ordinary cesspools are circular
excavations in the ground, lined with stone or brick laid without mortar.
They vary from 5 to 10 feet in diameter and from 7 to 12 feet in depth.
Sometimes the top is arched and capped at the ground surf ace by a
cover of wood, stone, or cast iron. At other times the walls are carried
straight up and boards or planks are laid, across for a cover, and the
entire structure is hidden with a hedge or shrubbery.
[Illustration: Fig. 18.--How to waste kitchen-sink drainage. _A_, Sink;
_B_, waste pipe; _C_, trap; _D_, clean-out; _E_, box filled with hay,
straw, sawdust, excelsior, coke, or other insulating material; _F_, 4-inch
vitrified sewer-pipe, hubs uphill, and joints made water tight for at
least 100 feet downhill from a well; _G_, 4-inch vitrified sewer pipe,
hubs downhill, joints slightly open, laid in an 18-inch bed of coarse
sand, gravel, stone, broken brick, slag, cinders, or coke; strip of tarred
paper on burlap or a thin layer of hay, straw, cornstalks, brush, or sods,
grass side down; _I_, 12 inches of natural soil; _J_, stone-filled pit.
As here illustrated, water is drawn by a pitcher or kitchen pump (_K_)
through a 1-1/4 or 1-1/2 inch galvanized-iron suction pipe (_L_) from a
cistern (_M_). The suction pipe should be laid below frost and on a smooth
upward grade from cistern to pump and be provided with a foot valve (_N_)
to keep the pump primed. If a foot valve is used, pump and pipe must be
safe from frost or other means than tripping the pump be provided for
draining the system.]
Except under the most favorable conditions the construction and use of
a cesspool can not be condemned too strongly. They are only permissible
where no other arrangement is possible. Leaching cesspools especially are
open to these serious objections:
1. Unless located in porous soil, stagnation is likely to occur, and
failure of the liquid to seep away may result in overflow on the surface
of the ground and the creation of a nuisance and a menace.
2. They retain a mass of filth in a decomposing condition deep in the
ground where it is but slightly affected by the bacteria and air of the
soil. In seeping through the ground it may be strained, but there can be
no assurance that the foul liquid with little improvement in its condition
may not pass into the ground water and pollute wells and springs situated
long distances away in the direction of underground flow.
For the purpose of avoiding soil and ground-water pollution cesspools have
been made of water-tight construction and the contents removed by bailing
or pumping. Upon the farm, however, this type of construction has little
to recommend it, for the reason that facilities for removing and disposing
of the contents in a clean manner are lacking.
In some instances cesspools have been made water-tight, the outflow being
effected by three or four elbows or =T=-branches set in the masonry near
the top, with the inner ends turned down below the water surface, the
whole surrounded to a thickness of several feet with stone or gravel
intended to act as a filtering medium. Tests of the soil water adjacent to
cesspools of this type show that no reliance 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 17 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 ventilation. 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 extending 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.