Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1907-08-06

NEW DE- w aOL / LhN
Grinnell's RemodeIed Disposal Sys-
tenn Believed to be Adequate to
Demands Made Upon It - Old Sys-
tenn insufficient.
Special to Times Republican.
Grinnell, Aug. 6.-Grinnell, like many
other cities OF the state, has been
bothered with the problem of dispos-
ing of its sewage, and considerable
money has been spent in efforts to
devise q system Of publication and
disposal that is satisfactory. Several
methods have been tried and all found
wanting, but the remodeling of the
present disposal plant on new lines
the question for all time.
A brief comparison of the old tank
with the new one may be of interest
at this point The old tank consisted
With the new one may be of interest
of three compartments of the follow
ing dimensions, 10x2S, 15x2S. and 20x2S,
all Of them six feet deep. 1t was COW
cred with roof of Is flooring laid on
wooden joists and more or less storm
water and free air was thus admitted
to the tank. The effect of these con-
ditions was to make it essentially a
settling tank. This is proven by the
20 tbat 1x-hn ~ 81, a
year or so since there was nearly four
feet of sediment in the bottom, con-
sisting Of solid sewage matter and
dirt which had been washed in from
the storm sewers.
The new tank consists OF three
compartments 10X50, 15x75 and 20x12S.
all eleven feet deep and all covered
by an ART tight roof of reinforced
concrete which is practically air
tight.
The sewage is taken at the top of
the tank and by means of special cast
iron fittings is delivered to the proper
compartment about IS inches from
the bottom thereof
The flow of the sewage thru the
tank is retarded by a series of BATTLE
walls which extend downward from
the top of the compartment to within
about four feet of the floor and from
the main compartment 1T is removed
to the weir chamber thru cast iron
fittings which permit of the flow being
taken only from near the bottom. In
this weir chamber the final stage Of
purifica ton takes place and the efflu-
ent is practically clear and odorless.
This system of sewage publication
is really an amplitication of natures
method of getting rid of decaylng
matter it being well known that ma
ture provides means to this end. The
principles used are retarding the flow
Of incoming sewage by means of spec
ial fittings and BATTLE walls, the dead
air space which is insured by the air.
tight concrete roof the proper proper
tioning of water and air space and the
proportion of length to width of the
compartments. When these conditions
are properly complied with, the de-
velopment of what are called anerobic
bacteria is not only made possible but
are most favorable therefor and 1t is
upon these that dependence is placed
for proper publication. The aneroblc
are distinguished from the aer-
ohio bacteria by the fact that
they are capable of living
and performing their normal func-
lions without the light of the sun or
free air. in fact these would destroy
them. They are the most efficient
agent known for the publication of
sewage and the object of all the APP
paratus used is to make the conditions
for their development as favorable as
possible.
No chemicals are used and they
would be worse than useless as they
would make the conditions most I'M
favora Bile for their development. About
two hundred feet above the tank is
placed storm water interceptor which
is intended to prevent change of level
of the contents of the tank by the
sudden influx of a large body of fresh
water during heavy storms. This IN
terceptor removes the storm water
from the sewer but permits all the SOL
id matter to enter the tank. The nat
ural life of these bacteria is about
70 hours and the flow of the sewage
thru the tank is made to correspond
Herewith.
IF this new septic tank does all that
only be free from any offensive odor
but will be nearly as free from disease
bearing germs as the water used by
many cities and towns.
1t is expected the flow of sewage
will be turned into the tank within the
next two weeks and the practical use
of it will demonstrate the truth or
falsity of the theory upon which the
construction is based. AS proof that
the theory is correct Mr. Anderson
shows statement of an analysis of
the sewage of three thousand people
as it entered such a tank and one
made at the outflow thereof.
These show the inflow to carry be-
tween four and five million bacteria to
the cubic centmeter while the outflow
reveals only $500 to the cubic cent?
meter.
If this tank Will prevent the pollu-
ton of the water in the streams below
the outlet ii will be money we'll in
vested and will speak well for the
Indictment and sa1acity of the council