The Portland daily press., 1895-04-02


tant factorsis therefore ADDED TO the con
ditions ana requirements, since the above
mentioned Recommendations were mad,
by Mr.. Shedd.
The territory hich is now to be consid
cred eoinprehends that which naturally
drains into the Back Cove between Turkey :,
bridge and the line of the town of Deering
and thence as far north as the area which
can be severed into the present Deerins
main sewer extends.
The remaining wafer sheds draining in tt
the Cows will also be improved eventually
with residence property. Then in due tins
sewerage will be required. But this terri
tory may now be properly ignored because
the exact extent OF the same is not as ye
clearly indicated. Most OF it is to low tt
be severed into the Deering main sewer
or, in fact, to any proper point OIL dispose
by gravity. The treatment of these areai
Will form Il problem by itself and can bt
taken up Independently when the proper
time arrives. The. Deering main isewer has
been made sufficiently large SO ihat some
of their sewage may eventually De lifted
into it. Amy excessive quantity will prob
ably have to be taken around the east side
of the Cove.
A sewerage project, designed
to relieve the Back Cove, should
be of a permanent character
and satisfactory feraH times. II should bic
lased upon the best known principles
Whjleit may not be necessary 10 carry out
the entire project at once. every portion
which may be built should form snbstan-
tiel and permanent part thereof. SO that in
time in harmonious construction and oper.
alton of the whole will oe effected.
The first question 10 be considered in such
a project is the best final disposal of tine
sewage. 1t is not worth while to discuss the
feasibility of CRITICALLY purifying it. be-
cause the operation would be attended with
considerable expense, and because it is
quite unnecessary. The large body of water
aronnd.s the city, with its daily 1uctustion,
and a tide over nine feet in beighth. clearly
Indicates that diffusion and dispersion Of
che sewage in Underwater, as already suggest
ed by Mr.. Shedd, is he final disposal that
should be recommended to you at the pres
ent time. IL is doubtful even whether it
will ever be necessary to change this mode
of'disposal
The best point at which theisewage can
linus PEA BSust OlHIpJ
Rock. tor the reasons given b. Dir. Shedd
when he. rec commended this ontfall.
But this point need not tie used at pres
eat. A temporary disposal Will be satisfac-
tory for some ime and save considerable
expense. would suggest that the present
Quit fall be located in the deep water at the
bridge of the Grand Trunk railroad, where
there is quite suffit lent current to dislersa
and dilute The large quantity of sewage.
Still, it would he wise to obtain at an early
day a right of way to Pomroy's Rock, in
order 10 prevent future difficulties in seeur-
ing 1t.
At either out fall it is necessary 10 retain
the sewage during incoming tide, as other
wise it would he brought back into the
Cove.
When examining the feasibility of deliver
ing thu sewage from all the territory at
these points by gravity we find u deficiency
of grade. There is q low area which cannot
have its sewage delivered at either point
without pumping and this area should be
reduced as much as possible, without injur-
ing he successful operation of he gravity
delivered. An intercepting sewer for the
higher territory and
A PUMPING Project
for the lower one, are the means to 4
adopted to prevent any future trouble in
the Back Cove.
The area which is no6 slnied and pollut-
ed with sewage. deposited between the Mar
ginal Way and the shore line. should be
filled up 10 above highwater mark as soon
as practicable, as the only means of abat-
ing the nuisance arising therefrpm. The
proposed Sc ers will not prevent shis nui-
sance, but would allow it to continue or
years. cause the large amount of matter
already deposited will disappear Zoo slowly
even if no more were aided to it.
Tits of great Importance to include in the
gravity system. if possible. the territory
of Deering. because of the large quantity OF
sewage eventually TO be delivered from it,
This requires the main sewer to cross
behring's bridge, the lowest point between
Deering and Portland. By raising the tle-
walton of the street at The bridge about Two
or three feet SO as to give sufficient cover
ing to the sewer, il will be practica Bile &c
include Deering in the gravity system. II
might be possible to convey the sewage
across the depression, by using an inverted
syphon, and thus avoid the raising of the
street. Though such syphons are entirely
practicable. it is nevertheless advisable to
do without them if possible, and l trust
that there will be no obstacle in the way of
this by change of grade.
Mr.. Shedd assumed for the interceptor a
slope of in 1000. This gave for the largest
section, and for a smooth interior, a yeloci-
of aboutss2.3 feet per second when run
ming full. ! have adopted the same slope.
1t is the least that will, think, accomplish
She desired results. The velooities which
it is possible to obtain in the largest size
of the sewer which I now recommend will
be about.2.S feet perIsecund when running
full.
In view of the, great advantage of includ-
ig Deering. we must endeayOr to counterfeit
the effects of this minimum slope and the
onsequent slight yelocities by increasing
the interior snoothness by plastering OF
neat Portland cement and by devoting
special care to the subsequent maintenance
particularly by frequently flushing the
sewer.
In calculating the velocity have assumed
a degree of roughness of the interior sur
face, or n. to equal 0.0l3, (IIufter's formula. }
equivalent to that of the Sudbury Cond uii
in massachusetts, where plastered with
hull of ~, hui