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DT SSRCAT MG MEI CA Acs BSN EST ECY EC)
For College Grove
iL.J,VANSKIVER
1903

 

 
THESIS

 

 

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PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before date due.

MAY BE RECALLED with earlier due date if requested.

 

DATE DUE

DATE DUE

DATE DUE

 

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6/07 p:/CIRC/DateDue.indd-p.1

—————
THESIS.

DESIGN OF SEWER SYSTEM FOR COLLEGE CROVE.

WA
I’. Je Vanskiver.

on,
THESIS”
_1-

fhe design of the sewer system for Colleze Grove,
began by a survey to obtain the topography of the plat. ihe
levels were taken with reference to the bench mark on College
Hall, because all the levels, in this vicinity have been
taker with refererce to this bei.ch mark, and could easily
be compared with. those of.the plat. ‘the ievels were taken
at the lot corners, as this method would save the tine of
following out even contours, and then establishing lines on
which to run. the levels. As the ground is very e.en, and with
a slight, but gradual slope, these levels also served to
obtain the profiles of the streets and alleys.

A map of the plat was then made, and the le:els
wore plotted direcely on the map. No centour lines were
drawn, as they were not needed. An inspection of the levels,
as plotted, being all that was necessary to determine the
natural water courses. Zhse all slope toward the South
Easi corner of the plat, and this was chosen as the out -

let of all. the sewage.

The next step, which aiso figures somewhat in

104024
~2-
the selection of the sewer lines, is determining the method
of disposal of the sewage. The usual method of disposing of
sewage, is io turn it into neighboring streams, and, in this
particular cage, the Lest an most economical method would ba
to turn it into the Red Cedar river, if that were possible.
but, the only natural water course, running from the plat
to the river, rar direcily across ihe College Campus, and
according. to. the staie law, no sewers can be put through
public property without a special permit. As ihis permit
could not be obtained, some cther means had to be used of
disposing of the sewage. another means of dispesal would be
to purity the sewage by means of a septic tank, and let the
purified sewage run offi through the ditch, ocr small strear.
which flows along the East side of the plat, and tnence
across the Campus to the river. This method was the one
adopted, and a septic :ank is to be installed on Charles
ste, opposite the alley between Ihe Elms and Albert ave.
This place was selected because it was the most convenient

place for the collection of ali the sewage.
 
-&-

The sewer lines were then selected. Many routes
could be selectea, but the most economical ones were found
to be ir the alleys. Ly placing them in the allevs, it will
requiee fewer sewer lines, as is seen in the sewerage of the
lots between Albert ave. and. fhe Eims. By placing the sewer
in the alley, the one line will serve all the lots, while
if the sewer were placed in the street, two lines would be
necessary, one an Alvert ave. ard one on The Elms. In the
case of the alleys parallel to M. A. C. ave@e, it was thought
more economical to place sewers in these alleys, as otherwiss
it would recuire sewers in Grove Ste, Me Ao Ue aV&Geyg and
Charles ste Of course, if the plai were buiit up rapidly,
and require an enlargemert, so that lots would have to be
laid out on the West side of Grove st., ana the Easi side
of Charles st., it would nct make any very material dif-
ference, whether the sewers were placed in the streets or
in the alleys. Eut from the present outlook, such additions
to the plat would probably not be made during the life of this

sysiem, and therefore the plan adopied seems to be the most
 

 

 
economical one.

An estimate of the amount of sewage was made by
assuming six persons to a lot, and that the amount of sewage
per capita was 0.0162 cu. ft. per minute. These were consider-
ed as very good \alues for a residential cistrict. Estimai-
ing the amount in this way, the sewer through the East alley
does service for twenty four lois, or one hundred forty four
persons, making the amount of sewage l44 x .0162 ~ 2.552 cu
ft. per minute. The sewer through the hest alley does service
for the same amount or 2.5¢2 cu. ft. per minute. Along Anna
st., the increase of sewage is from five lots or thirty per-
sons, making an increase of .486 cue ft. per minute. In the
Alley between Alpvert ave. and the Elms, the sewer serves
twenty four lots or one hundred forty lour per sons, making
£.552 cue ft. per minute. This maxes the total amount for
the whole plat 2.552 + 2.252 + .486 + 2.552 - 7.“84ou. ft.
per rinute. According to the diagram which gi:es the capacity
of sewers on diiferent grades, this amouni is considerably

less than the capacity of a six inch sewer on a tive tenths
_6-
percent grade. As no grades wiil pe less than five tentns
percent, a s1x inch pipe would allow a cconsiderabie factor
of safety.

After the selection of the sewer lines, protiles
were madé of the streets and alleys through which they were
to run for the purpose of determining the vest grades for
the sewers. The profiles were drawn to a horizontal scale
of one inch ecuals fifty feet, and to a vertical scale of one
inch eywual to five teet. The distances were computed fron
the widths and lengths o!: the iots and streets. betore de-
termining the grades and depths oi the sewers, it was found
necessary to take the levels at the bottoms o1 the oellars
which the sewers would drain, and also the elevation of the
ditch thai flows across the Campus, ana into which the tank
would empty. The elevation ot this ditch was a very importan*

item in determining the depth.of the sewer at the outlet,

as ample fali had to be proviaed for between the sewer and
the ditch to carry off.ihe purified sewage. ihe mouth o/ the

sewer was placed about a foot higher than the bottom of the
-§-
ditch. ihis brings it about three feet below the surface a‘
this point which is considerea shallow, but as it lies in the
street, the streé) will probably be tilled in and graded up
higher, it it is ever improved. This was the first point de-
termined, and was the one upon wnich all the grades were
based as they had to be brought to this elevation at the out-
let.

ihe depth of the sewer in the alley parallel to
The Elms was determined principally by the elevation oi the
cellar oi the store at the hest ond. io brirg it below the
cellar, the sewer had to be lowered io about nine feet be-
low the surface. Examining the profile, the point was seleci-
ed at which the grade would have to be chang@dy ard an ap-
proximate depth of sewer determined at that poirt. ‘hen
beginning at the outlei and working backwards, an e\en
grade was determined which would bring the sewer at about
the depth required at that point, care bei:rg taken that the
sewer did not run too deep or toc shaliow at the inter-

mediate points. After having determined upon the pest grade,
-7-
the depth of the sewer was computed acourately at the point
where the prade was to be changed, anc with this depth,

the grade and depth of the sewer aboie was determined in the
Sane way.

The grades of the sewers along Charles and Annz
streets were next determined. ihe voveenire factors in this
case, were the depth of the sewer at the outlet, and also,
the fact that the sewer along Anna st. had to be deep
enough to afford an outlet for the sewers in the East and
hest alleys. Inspecting the profiles of the iwo alleys, an
approximate depth was made at the mouth of each, which
would be sufficient for the mouths of the sewers in the al-
leys. Then beginning at the outlet, even grades were de-
terminea which would bring the sewer at the required eleva-
tion at the alleys. ihe elevation of the sewers at. the
mouths of the alleys were then computed accurately, and the
grades in the alleys determined with reference vo these

points. In determining the grades, the method ot beginning
-8-

at the outlet and working backwards, was used so as to
avoiac using fractional graces, and thus facilitate the work
of seiting grade staxes.

Manholes are to be placed at all iniersections,
and at all changes of grade. At the dead ends lamp holes are
to be placed. It was thought that manholes at the dead ends
would not be necessary, uniess the sewers would sometime be
extendea. But in ail probability, sewers will not te ex-
tenced beyond the present design within the life of this
system.

The cost of. the s,etem was extimated as follows:
382] tt. &" tile © l2v per ft. ------------ 456.62

Excavating, laying, and backfilling,

231.6 rdse & $4.00 per rde = ----------- 926.40
7 manholes at «~SC.CO each ------------- 210.00
3 lampholes at %5.CO each ------------- 2, -LB2GQO_

Total - - ---- & 1609 .Y2
-- -_——_—= = -

 

     

 
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