Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1901-10-04
SEPTIC TANK system.
Method OF Sewage Publication
in Marshalltown Is Com
mended.
City Engineer. Of Vancouver. B.
C.. Says II Is the Only Salts.
factory System.
His Views 40 Printed in the Amer
lean Medical Journal With
Explanations.

According to the statement of Col. j.
n. Tracey, city engineer of Vancouver,
B. c., the septic tank system of sewage
disposal, adopted by the city Of Mar
shalltown, is the only successful and
practical method of sewage publication.
The same system is in operation in Van
couver, and so many are the inquiries
from other cities that Col. Tracey. in
order to answer all, has published in
pamphlet form description and COM
parison of this and other methods. In
the American Medical Journal, one of
the leading publications OF its class in
the country, Col. Tracey's views are
published, and because of the adoption
of the same system in Marshalltown and
the nearing OF completion of the plant,
they are reproduced In these columns.
Col. Tracey Gays:
1.-The economical disposal of sewage Is
problem which has engaged the at
tention of engineers and scientists for a
great many years with varying results.
sand filtration, sewage farming,
chemical precipitation and bacterial fl
tration are the most notable processes
tried and found wanting. The objection
to each OF these processes are briefly as
follows:
Sand filtration, continuous or inter-
mittent.-The area Of suitable sand
ground required is usually difficult to
obtain in the neighbolhood OF city, and
il obtainable the elevation or position is
such az to necessitate pumping and con-
sequent continuous expense.
Sewage farming II, growing into dis
use for principally the same reasons.
chemical precipitation is expensive,
both on account Of the cost Of the chem
icals and handling and also the dealing
with the .sludge' which Is produced in
excessive quantity. The eftiuent is also
liable to become offensive.
Bacterial filtration. - Considerable
success has attended this method Of
treating sewage, but taken alone there
are objections to it In treating raw
sewage the filters become clogged and
require to be OF considerable size and
consequently expensive construction.
Septic tanks. The most effective
method OF treatment of sewage SO far
known is the septic tank, either used
alone where the discharge Is into salt
water or where q high degree of purifi-
cation is not necessary or In conjunc-
ton with bacterial filters where the eff
fluent must be comparatively pure. The
tanks are usually constructed OF con-
crete, arched over and Of q capacity
equal from eighteen to twenty-four
hours, flow of sewage with a depth of
about five feet, the inlet and outlet pipes
being turned down to depth Of about
eighteen feet below the surface, SO as to
leave the scum, which forms on the sur
face, and in which the bacterial action
is carried on, undisturbed. After the
tank has been In llae about a week a
brown scum forms en- the surface. which
gradually increases, until the full ac-
ton Is attained. In this scum the action
of what are known as anarobic bacteria
goes on, the greater part OF the sewage
being liquefied and a very small deposit
resembling black ashes being deposited:
that about 90 per cent of the organic
matter in suspension and about 30 per
cent OF that in solution are removed and
that the deposit does not require to be
removed for several years. The practi-
cal result undoubtedly is that the Of
fensive matter OF the sewage is de-
tstroyed and the eiiiuent is sufficiently
clear for dlschargi.ng into salt water or
where a high degree OF publication is
not necessary. +
Where discharged into a running
stream or where greater publication is
desirable small bacterial filter or set of
| filters may be added In such case a
much smaller area Of filter is necessary
| than II filters alone are used, as the eff
fluent from the septic tank will go thru
at least four times as fast as the raw
sewage. and the filter beds are not liable
TO be clogged.
THE Vancouver septic tanks are three
In number. designed for populations Of
5000. 5000 and 1000 respectively, and
were constructed in 1900 from plans fur
rished by the Septic Tank Syndicate,
the first being put In. operation about
Jan. /, 1901. and the others month or
two later. The results so far (August)
are quite satisfactory, tho the quantity
OF sewage passing thru is not such as to
make the conditions most favorable for
the development of bacterial action In
one of the tanks near the creamatory
| the scavengers have been dumping night
soil to the extent of five or SIX loads a
might, and, tho the last tank to be put
in operation, the effluent is the clearest.
There have been no analyses yet
made either Of the sewage or the eff
fluent, but the practical effect Of the
bacterial action is very apparent. There
is no smell from the tarnks or the eff
fluent The earth has been filled over
the tanks, leveled and seeded, SO that
the appearance OF the surface IL not un-
slightly or offensive in any way.
Some slight changes have been made
in the plans furnished by the syndicate;
in order to avoid the use of wood COW
ering for the inlet and effiuent channels
the concrete walls having been contin-
ued up and arched over, leaving only the