I! E P OR T
ON A
PROJECT FOR* THE DRAINAGE
OF
BOMBAY.
ALSO
REPORT 01ST
Mr. SOWERBTa? MEMORANDU'M
ON THE DRAINAGE OF BOMBAY.
BY
HECTOR TULLOCH,
CATTAIN KOVAL ENGINEEKS.
NOVEMBER 1808.
^ 0 lit b 3 It:
* >— 'O
rHINTED AT THE
EDUCATION SOCIETY’S PRESS, BYCULLA
1SC8.
REPORT
ON A
PROJECT FOR THE DRAINAGE
OF
BOMBAY.
BY
HECTOR TUBLOCH,
C'APl'AIN royal engineers.
NOVEMBER 186S.
PRINTED AT THE
EDUCATION SOOI ETY'S PRESS, BYCELLA.
18f>8.
Bombay, 2nd November 1868.
From the MUNICIPAL COMMISSIONER of Bombay,
To the SECRETARY TO GOVERNMENT,
Department of Public Works.
Sir,
In forwarding Captain Tulloch’s Project for the Drain¬
age of Bombay, my health does not permit me to do more
than make a few general remarks. I regret this because
I have had daily consultation with Captain Tulloch on the
subject as his scheme matured, and there is no detail which
has not been fully discussed between us.
â–  The project appears to be entirely in accord with the
views of the Secretary of State and the recommendations of
Mr. Rawlinson.
It proposes to utilise the sewage for irrigational pur¬
poses at a point distant from the town, and thus in the long
run to make the works remunerative.
We do not need to learn in India that irrigated land is
highly productive, and it is a fair inference that land
irrigated with diluted sewage would be even more produc¬
tive.
We are told by all who have seen the sewage irriga¬
tion farms in Europe that no nuisance whatever is caused
by the use of sewage in this manner, but we have yet to
combat this bugbear here.
This is a simple matter. The question will be tested
during the present season on a small scale in the neighbour¬
hood of the Love Grove Sluices. •
11
Meanwhile the project may be fairly discussed on
its general merits apart from the proposal to utilise the
sewage—for if such utilisation is found a failure the sewage
o o
can still be discharged at Colaba or anywhere else at a less
cost.
Captain Tulloch’s project differs from Mr. Aitken’s
in the following important particulars : —
1st. Capt. Tulloch drains
the whole island and the
city, present and future.
2nd. Capt. Tulloch sepa¬
rates the storm waters from
the Sewage, as suggested by
Colonel DeLisle, General
Tremenheere, and Mr. Or-
miston, and thus reduces the
size and cost of his sewers.
3rd. Capt. Tulloch drains
off all the floods on the town
and flats, and disposes of a
rainfall of 14 inches in the
24 hours.
4th. Capt.TulIoch’sMain
Sewer follows the natural
valley of the Island.
5th. Capt. Tulloch pro¬
vides in his estimate and
plans for all street drains, and
his is thus a complete esti¬
mate.
6th. Capt. Tulloch’s com¬
plete scheme is financially
possible*.
Mr. Aitken leaves a great
portion untouched.
Mr. Aitken carries both
rain water and sewage toge¬
ther in huge costly drains
which will be empty during
eight months of every year.
Mr. Aitken leaves the
question of the flats untouch¬
ed, and deals with a rainfall
on the town only of but 4
inches in the 24 hours.
Mr. Aitken’s runs in the
opposite direction.
Mr. Aitken only deals with
main and principal sewers,
and leaves us in doubt as to
the ultimate cost ofthewhole
scheme.
Mr. Aitken’s incomplete
scheme has been pronounced
financially impossible.
Ill
It remains now for Government to decide how this
question can he best discussed and settled, by special com¬
mission or otherwise.
Captain Tulloch only desires a fair field in which he
may meet all objectors,
A question of this importance cannot be too freely
ventilated, and i have, therefore, in anticipation of the sanc¬
tion of Government, placed the papers at the disposal of
the press.
Captain Tulloch is publishing a separate paper which
effectually disposes of Mr. Sowerby’s Project.
I have the honour to be,
Sir,
Your most obedient Servant,
ARTHUR T. CRAWFORD,
Municipal Commissioner for the City of Bombay.
REPORT
ON A
PROJECT FOR THE DRAINAGE
OP
BOMBAY.
The harbour considered as an
outfall.
Until the publication of Mr. Rawlinson’s last Report
on the Drainage of Bombay, dated
January 1868, the prevalent idea in
the town seemed to be that the sewage sh,ould be dis¬
charged into the harbour. The reasons for this proposition
have never seemed to me at all satisfactory. The greatest
argument in its favcrur is that Bombay lies to the windward of
the harbour. Almost every other consideration will convince
us that the harbour is badly suited to the purposes of an
outfall.
I will first show the aspect of the question from a phy¬
sical point of view. If the Island of Bombay sloped down
towards the harbour there would manifestly be a great
advantage in taking the sewage in that direction, but the
slope of the greater portion of the Island is actually in the
contrary direction—right away from the harbour towards
the west. It is clear, therefore, that if the outfall is situated
in the harbour the sewage will have to flow in the opposite
direction to that in which it would flow if left to itself.
4
Now the only way in which this could be effected would be
by putting the sewers at a great depth belowground ; so, on
the face of the thing, we should be driven to a most
expensive expedient to carry out an arrangement for which, as
I shall presently show, there is no necessity.
If, however, the sewage were discharged into the
harbour, would the inhabitants be rid of it ? In considering
this question it should be borne in mind that the only
facts we have on record to guide us are Mr. Jaggonath
Sadasew’s float experiments. They are valuable so far as
they go, but they are very imperfect. Such as they are,
however, most people who reason on them will probably
come to the same conclusion. This is, that casting the sewage
into the sea on any point on.the eastern side of the island
may be attended hereafter with some risk to the health of
the inhabitants, and that much nuisance must inevitably arise
to the shipping from such a course of proceeding. It may'
be contended by a few that the sewage, being mixed with
so large a body of water, would become extremely diluted,
and thus be rendered harmless. I am not of that opinion.
I am told that the nuisance even from the present main
drain of the Fort is at times very great. Even if this were
not so, I should still hesitate to draw the inference that
because there is no nuisance at present from this drain
therefore there will be none in the future from the main
drain of Bombay. The nuisance from foul matter of any
kind must, ceteris paribus, be directly proportional to its
quantity. Now the main drain of the Fort is, comparatively
speaking, quite an insignificant work. It conveys away
the sewage of only about 80,000 people, and does this
under an incomplete system of drainage. When Bombay
is drained under a complete scheme, the main drain, where-
ever it may be situated, will have to discharge the sewage
of nearly one million people, and fifty years hence of
probably two millions of people. Let me try and convey
to the mind what this means. It means 4,400 cubic feet
of sewage every minute, night and day without interrup¬
tion. Wherever on the coast such a large quantity of filthy
matter is discharged, I maintain that it will make its presence
known. Indeed the most serious consequences might
arise if we acted on a judgment, founded simply from
considering the main drain in the Fort, which, except
during rainy weather, has not more than 12 inches of water
flowing through it during the day.
What gives Bombay its importance in India is its
magnificent harbour. No other town in the peninsula
offers such great facilities to the shipping trade as this
favoured little Island. If it is the harbour which makes
the town, as I should fancy all will admit, would it not be
indiscreet, to say the least of it, to do anything that should
detract from the advantages which that harbour holds out
to all the world to trade with India? Before, therefore,
discharging the sewage into the sea at Colaba, should it
not be shown by the advocates of that measure that the
sewage could not return to the harbour nor cause a nuisance
there? Can these propositions be maintained with even a
show of reason in the face of Mr. Jaggonath Sadasew’s float
experiments, all of which with hardly an exception, go far
to prove the direct contrary? Could even the majority of
those interested in the question be got to believe in them ?
Until it is clearly demonstrated that the sewage of Bombay
cannot be got rid of otherwise, the harbour should never
be permitted to be polluted with it.
Looking at the question of drainage from a purely
engineering point of view, and setting
aside for the present all sanitary
The advisability of draining the
town towards the flats.
6
considerations whatsoever, I hope to be able to prove the
necessity of the abandonment of the harbour as the outfall.
A careful examination of the accompanying map of
Bombay* on which the levels of the different districts and
streets are marked can hardly fail to convince an engineer
that the natural drainage line rims along the following
streets :—Syed Abdool Rahimon street, Bappo Kote street,
Falkland Road, and so on to the Flats. This is clearly the
valley line, and, therefore, from a prinvl facie point of view,
the direction in which the main sewer should run—provided
of course that no objection of a serious nature can be urged
against it. There is a very serious objection which compels
us to abandon this line. That objection is that the present
main drain which, in parts, is 20 feet wide, runs along this
very valley line. The new main sewer could not be built
in this direction without destroying this large drain, which
will still be required for purposes of rainfall. In altering
the course of the main sewer, I propose to carry it along
those streets which run as close to the valley line as
possible.
The first advantage which will be secured by adopting
the valley as the main line of drainage will be that all the
street sewers will have better slopes than could be given
to them under other circumstances. It is impossible for
me to prove this by any amount of writing. But if any one
should doubt the statement, he can easily test it by running
the main sewer along some other line. He will find that
the nearer the main sewrer runs to the valley the better will
be the slopes of the street sewers, and that the further the
sewer is removed from the valley the worse will be their
slopes. The importance of this can hardly be exaggerated,
inasmuch as the successful working of every system of
* Vide Plan No, 1.
7
‘drainage depends more on the slopes of the sewers than
perhaps on anything else. The less the slopes the greater
must be the deposit in the sewers, the greater the slopes
the less the deposit.
The second great advantage of carrying the sewage
towards the flats is. connected with the soil. On the
accompanying map of Bombay* the geology of the Island is
delineated. It will be seen that the nnain sewer will run in
the “ alluvium and superficial deposits,” the strata which are
the cheapest for the engineer to work in. There will
be a little rock cutting involved in the branch sewer
to the Elphinstone Reclamation, but under any system of
sewerage some rock cutting would be necessary. The
eastern portion of the Island is separated from the rest of
the town by a ridge of hills of trap rock. It would therefore
manifestly be impossible to bring the sewage of the two
districts to one point without passing through the hills. •
If the depth of cutting which always'materially affects
the cost of drainage works be considered, it will be found
that it is* far less under the proposed system than that
which any other line of main sewerage would involve. In
fact, the depth of the cuttings will be moderate throughout,
and wherever rock abounds there the cuttings for the street
drainage will be reduced to a minimum.
But perhaps the greatest of all advantages will be of a
prospective nature. In an important town like Bombay
which has already set up its claim to be considered the
capital of India, and which is increasing in size, population,
and importance every year, no system of drainage should
be adopted which will not suit her growing requirements.
The scheme to be carried out should be so comprehensive
* Vide Plan No. 2.
8
that in whatever direction the town might spread the
drainage of the new parts should fit in at once with that of
the old. I do not mean that the system of drainage should
be so complete that nothing further should be required,
for that would be.absurd. New works must be executed
as the town spreads, but they should still form part of one
grand scheme. They should be additions to that scheme,
not systems apart from it.
I am given to understand that the direction in which the
town has always shown a tendency to spread is towards the
Flats. Now as this is the direction in which it is proposed
to take the sewage, it should be clear to evei’y one that this
is the very part of Bombay that would drain the best of
all. The main sewer would pass through the Tlats and of
course the most rapid falls could be secured for the street
drains.
But this is taking a very simple case. I will put a much
more difficult one. Suppose the town were to spread a
mile beyond Parell, or suppose even that the whole island
were to be covered with habitations, how would, the pro¬
posed project answer in that case ? My reply is that this
project has been expressly designed for the drainage of
the whole Island. A short inspection of the accompany¬
ing map of Bombay* will show that the lowest portion of
the island is the valley running from the Flats right up to
the northern coast. Now if the entire island were thickly
populated, all that would be required for its drainage
would be to carry a sewer from the north along the bottom
of this valley to the Flats. I have so arranged the levels
of the proposed works that this sewer would be at a suffi¬
cient depth below ground to drain the whole of the island
* Vide Plan No- L
9
effectually, and would enter the Pumping Station at Love
Grove at the same level as the sewer from the south. In
other words, all the sewage of the future town of Bombay
could still be concentrated at one point, to be there dealt
with under one management. And this brings me to the
question of pumping.
Whatever outfall may be selected it is a physical impossi-
Thenecessity for punning the bility to discharge the sewage without
the help of pumps. A large portion
of Bombay lies below high tide level. Some parts of the
island are elevated only a few feet above low water mark.
Under these circumstances • it is clear the sewage could
notbemade to flow into the sea without artificial aid. . Nor
is the case altered if we decide to utilise the sewage on
land. There is no land lying at a sufficiently low level and
away from the influence of the tides on which the sewage
could be used without first being raised. It is thus a matter
of necessity (in which the engineer has no choice at all) to
employ pumping in order togetrid of the sewage. Ifthistruth
be recognised as established,! will try and point out the advan¬
tages to be gained by leading the sewage towards the Flats.
The Flats near Love Grove are, I should fancy, too well
known to need any description at my
The Reclamation of the flats. -it t * • i *
hands, it is universally admitted
among sanitarians that a high death rate generally accom¬
panies swampy ground. Indeed, one of the most essential
conditions of health is a dry dwelling. Dirt and stagnant
water abound in low lying districts. If we rightly estimate
the value of houses free from damp \ye must see the
importance of preventing the Flats from being inundated,
as they now are, i.c. for about five or six months together
at a time. I feel certain that the reclamation of the Flats
would in a very short time be followed by a reduction in
3 D
10
the death rates throughout the town, and no drainage
project therefore should command the confidence of the
inhabitants which ignores the necessity of preventing the
formation of swamps in the island.
It has been proposed to raise the Flats, but I cannot see
what good result, commensurate with the cost, would
follow, unless the whole of the island were raised above
high tide level. It appears to me that the reason why the
Flats are swamped has not been sufficiently considered, or the
proposition of elevating them would never have been made.
Taking mean sea level at 50 feet above datum line, the
following will be the levels of the different tides : —
High water spring tides 57*25*
High water neap tides 55*00
Mean sea level 50*00
Low water neap tides 45*00
Low water spring tides .. 42*75
The Flats vary in level. Parts are as low as 47*00.
There is a considerable area at 48. The average level may
be taken at about 49*00 or 50*00 and the highest level at 54.
Now when a storm overtakes the town it depends entirely
on the state of the tide at the time how deep the lower
parts of the island are under water. The greatest storm
that has ever visited Bombay during the last 20 years was
that of the 9th of August last, when 14*21 inches of rain
fell in 24 hours. Parts of the town were three feet under
water. The level of the water on the Flats was at 54*50
above datum, and the level of the water in the town stood
as high as 58*00. The tide rose to 55*83. In such storms
the rain collects on the Flats very much quicker than the
sluices at Love Grove and elsewhere can discharge it, and
* To reduce these levels to Colonel DeLisle’s datum add 29*70 to each.
11
the effect of raising the Flats without enlarging the sluices
would simply be to throw a larger body of water on to the
town. The water must accumulate somewhere. It cannot
escape to the sea, because the sluices are not nearly large
enough. During spring-tides the sea would for several
hours be higher than the floods, and the sluices could not
be kept open at all. Where then is the water to stay
during this time if the Flats are.raised ? It is evident that
it must run to the lower parts of the island wherever they
may be, and these will then take the place of the present
Flats and become the swamps of Bombay in their turn. So
that all we shall have done by elevating the Flats will be
virtually to remove them to some other locality. Would
this be worth the expense ?
The fact is that before the Breach Vellard was constructed,
the town was not liable to floods by rain, because the
rain couldalways escape to the sea. It was, however, liable
to floods by the sea, because the sea could enter through
the breach. The construction of the Breach Vellard has
solved only half the problem. It has kept the sea out, but
unfortunately it has also kept the rain in. No one can
doubt this who has been in Bombay during the months
from June to November. The Flats are always under
water at that time. The remaining half of the problem is,
cannot the rain be allowed to flow into the sea so that
there shall be no swampy ground at all in the Island? I
am certain it can. Even after such an extraordinary storm
as that of the 9th of August last, if proper arrangements
had been previously made, the Flats should have been dry
the day after.
If I have rendered myself clear, it will be seen that
during heavy falls of rain some part or other of the island
must be under water; that if, in order to prevent this state
12
of things, it were determined to raise the lower lands, no
part of the island should be allowed to remain below the
level of high water of extraordinary spring tides, or below
COg- above datum. Unless this were done, there would
still be portions of Bombay liable to be flooded. But to
raise the lower lands to anything like this level would be
pecuniarily impossible. It is altogether out of the question
I do think, therefore, that the idea of relieving the town of
floods by raising any part of the Island should be entirely
abandoned. The difficulty must be overcome by other
means, but before pointing them out it is necessary that
the object in view should be kept in mind.
The area which drains into the Flats and the lower parts
of the island is 16 square miles. The greatest fall of rain
during the last 20 years is 14 inches in 24 hours, and this
amounts over that area to 520,000,000 cubic feet. This
is a tremendous body of water to deal with, but we know
for a fact that this quantity did actually flood the island on
the 9th of August last, and it would not be right to ignore
the circumstance. Thg problem which I have set to myself,
therefore, is this. Can 520,000,000 cubic feet of water be
run off into the sea in one day during those hours when the
tide is below the floods? The question is immensely
complicated by the fact that the problem varies with the
state of the tide when the storm takes place. If spring-
tides are prevailing the sea must rise above the level of the
floods, which cannot in that case be discharged for many
hours of the day. On the other hand, if neap tides are
prevailing, there will be very few hours when the floods
may not be relieved. At a first glance, therefore, it would
appear that the most unfortunate state of things for the
town would be for a great storm to take place while spring¬
tides prevailed. But this is really not the case. The worst
state of things is when a storm occurs during neap tides,
the very worst of all during extraordinary neaps. A little
consideration will render the matter clear.
. During spring-tides the sea rises of course very much
higher than during neaps, but on the other hand, it falls
very much lower, and this is of the greatest importance.
The head of water in the former case is considerably
more than that in the latter, and the consequence is that
during the hours at spring-tides when the sea is lower than
the floods, much more water can be passed off than during
a greater number of hours at neaps.
It is evident, therefore, that if during neap tides the
floods can be relieved in 24 hours of a storm of water over
the island amounting to 14 inches in that time, we shall
have provided for the worst state of things—a state that may
not occur in 50 years. I propose therefore to construct
three sluices each 120 feet long—one at Love Grove,
one at Worlee, and one at Daravee. These works with
the present sluices, will in one day discharge all the rain
(taken at 14 inches in 24 hours) which falls on the area
draining towards the Bombay swamps. That is to say,
that if a storm similar to that of the 9th of August last occurs
even during neap tides, the whole of the water standing
on the island will be discharged into the sea within a
single day.
The relief of the town from
floods.
The difficulty has not yet been entirely got over, for
there is another point demanding con¬
sideration. This is, that in great
storms daring those hours of the day when the sluices cannot
be kept open, the lower parts of - the town may still be
liable to floods in consequence of the rain not being able
to run off to the Flats as rapidly as it falls. In fact, the
question is whether the state of things which occurred on
14
the 9th of August last can be prevented. It may be quite
true that all the floods might, with proper sluices, have been
discharged into the sea in 24 hours, but would not the
water still have collected in the town itself, as it actually
did while the sluices could not be kept open, and in con¬
sequence of the mouth of the main drain being dammed up
by the floods on the Flats. This is a very important question,
and will show. that another great advantage has been
secured by this project.
J have already pointed out that pumping must under any
circumstances be resorted to before the sewage of Bombay
can be disposed of. By leading the sewage towards the
Flats we shall require the engines to be erected there.
Now these engines in a time of great emergency like a
storm will be most admirably situated for two purposes, in
addition to their ordinary one, viz. that of pumping up the
sewage only. The first is that of helping towards relieving-
the Flats, and the second, which is much the more important
one, is that of keeping the town from being flooded. We
can afford to let the’Flats lie under water for a few hours,
as nobody will be inconvenienced thereby, but it would
never do to let the town get swamped.
There will be three engines, each of 150 horse power.
Two of these will be sufficient, in ordinary dry weather,
for pumping the sewage to the irrigation lands. In times
of extraordinary storms (but not oftener on the average
than once a year) the sewage for a few hours might, with
hardly any nuisance, be pumped into the sea. If this
were done one engine would be enough for the purpose, as
the lift in that case would be only half of that required
when the sewage had to be raised for irrigation. Two of
the engines would thus be free for keeping the town dry;
and if the work of the third got slack, that is to say, if
it were the time of day when there was little or no sewage,
15
even the third engine could be put to the other duty. And
if all the engines were worked to their utmost power,
there would be about five or six hundred horse-power
employed in pumping the town dry.
These engines would draw the water directly from the
town itself by a sewer running under the Flats, and so
arranged that the floods on the latter would be entirely
excluded from the sewer. In fact the rain would be allowed
to collect on the Flats, but not in the town. The Flats
would be relieved as soon as the tide went down, and so too
would the town itself; but while the sluices could not be
opened and the rain continued, the engines would be
exerting their utmost power to keep the town dry, and,
even in the rare case of a great storm occurring simultane¬
ously with a neap tide, they would still, I believe, be
successful in effecting the desired object.
If extraordinary neap tides prevailed during the storm,
it would be impossible without the help of pumps to get
the Flats dry, because at no time of the day would the
floods be entirely above the level of the sea. Low water of
extraordinary neaps is 43-75 feet above datum, and parts
of the Flats are as low as 47. Over these parts, therefore,
there would be nearly two feet of water standing which
could not escape through the sluices even when the tide
was at its lowest. In this very peculiar case, after the
town had been relieved, the engines would be set to
work to pump the floods on the Flats, and the whole island
would be dry in the course of a few hours.
Now it should be clear that such a number of advantages
could never be secured by a project which had its engines
erected on the harbour #de of the island to pump the
sewage into the sea in that locality. By placing the
engines on the western edge of the Flats we shall be near
16
the sea, and we shall have them in the very best position
to meet all emergencies arising in times of great storms.
If, as I have shown above, some part of the island must
be under water for some hours during heavy rain, I trust
it will be granted that no object will be answered by raising
the flats. Indeed a very important one will be gained by
letting them be what they now are : at present they form a
reservoir for storm water while the sea rises above the
floods, and for this object I would still retain them.
Numerous projects appear to have been put forward for
reclaiming the Flats, with the view to
The flats should be converted ^
into a pai-k. fit them for building purposes. But
why should the Flats always be selected as eligible ground
for this object? They are covered with foul matter, and
I doubt whether the best sanitary arrangements would
make them habitable. It is much more probable that if
this portion of the island were built upon it would become
the centre of disease in Bombay, from which every one
Avould more or less suffer.
I should be the last to advocate that the Flats should be
converted to no useful purpose at all, or that we should
rest satisfied with having relieved them of floods. On the
contrary I would have them not only negatively harmless,
but I would make them positively healthful—a place where
all classes might go for recreation, amusement, and even
for pure air!
Bombay, with its million inhabitants, has no park; why
should not the Flats be made into one ?* The more the
subject is considered the better it will look. That very filth
* For tlie position and extent of the proposed park, vide Tlan No. 1.
The idea of a park was first suggested to me by Mr. A. T. Crawford, the
Municipal Commissioner of Bombay, to whom, therefore, ail the credit for
>o excellent a proposition should hr given.
17
with which this part of the island has been for years covered
has rendered the soil rich enough to produce any thing.
In place of a fetid swamp reeking with emanations from
all kinds of the foulest matter, we should have a garden
in which it would be a pleasure to walk.. Somebody has
well said that “dirt is matter out of placethat is just
the case with the dirt on the Flats, but it will certainly not
be so if this proposition of a park is carried out. Manure
is offensive only while there are no crops growing on the
soil, but as soon as the field isgreenthe nuisance vanishes.
It is wonderful with what rapidity the foulest matters are
absorbed and assimilated, into their systems by plants.
It is precisely because the Flats are so filthy that they
are so well suited for a park.
If we consider the position of the park with reference
to future Bombay, it is very favourable. The town must
’ spread towards the north, for the southern portion of the
island is nearly as thickly populated as it well can be ; the
park would thus stand about midway between the old and
the new town, and be equally convenient for the inhabitants
of either.
From a financial point of view the question looks equally
well. The land already belongs to Government, it will
therefore cost nothing to purchase. It would be a noble
act on behalf of the Government to present it to the Muni¬
cipality for such an excellent purpose. I feel confident
that hereafter, when the Flats are reclaimed and the soil is
cultivated, the park will not only pay its own expenses but
•be a source of profit to the town.
I have all the greater confidence in urging this proposi¬
tion on the people of Boiflbay, because I have seen a park
spring up under similar circumstances in another large
Indian town, and prove to be a great success. Only a few
5 D
18
years ago the People’s Park in Madras was a swamp and
a receptacle for the filth of the town—a pface which every
one avoided if he could, which literally stank in the nostrils
of the inhabitants. Now it is one of the loveliest gardens,
to which all classes resort during their hours of leisure.
Hardly any one could have anticipated the immense success
of the undertaking. ' There is no reason which I can see
that should prevent the Bombay Park being equally
successful. It will never do to let the town spread indis¬
criminately in all directions without preserving some open
spaces for health and recreation. The time must come
when the people will demand a .place of this kind. Now
there is the chance of securing land at nobody’s expense,
and, if the opportunity is allowed to slip, the people will
have themselves onlv to blame for it.
I need hardly point out that all the property about Maha-
luxtnee, Tardeo, Carnmateepoora, Byculla, Chinchpoogly,'
Worleeand other adjacent districts will be immediately en¬
hanced in value if the Flats are reclaimed as proposed in this
project, and still more if they are converted into a park.
Having already shown the numerous advantages that
will be secured by taking the sewage
The julvnnmgcs of this project . , v . n , , .
even if >rwngu utilisation pioves 111 1116 (lLreCtlOll Ol tile 1} Jell’S, it IS
a failure.
necessary that I should explain what
is intended to be done with it. My opinion is that Mr.
Ilawlinsoirs proposition to utilise the sewage overcomes
all difficulties regarding its disposal. But before entering
on this question, I wish to answer the arguments of those
who, being opposed to this scheme of sewage irrigation,
might be expected to put forth their objections somewhat
in this form. Of course if sewage can be utilised, there is
no doubt that is what should be done with it; but it is
questionable whether it will succeed in Bombay, and if it
19 .
does not, will not this project be a failure, and will not all
the expense that the inhabitants will have been put to in
leading the sewage towards the Flats be thrown away ?
Giving the objectors all the advantage they may claim on
this ground, I will assume that sewage utilisation turns out
not only to be a failure, but to be the most miserable of
failures—that not one blade of grass nor a pound of vege¬
tables can be grown—that the land refuses to yield any pro¬
duce of any kind, apply the sewage how we may ; then I
maintain that even in this case it will.be far cheaper to
take the sewage to the Flats and to pump it up there, than
to carry it direct to any other part of the island. It hardly
matters at all to this project, and that is a great advantage,
where it may be decided to take the sewage to ultimately.
For the sake of argument I will assume that its utilisation
having proved a failure the sewage is to be discharged into
the sea on the harbour side of Colaba. The only difference
then in this project would be that the irrigation pipe which
would have been taken to the north for the utilisation of
the sewaee would have to be carried to the south to dis-
o
charge the sewage into the sea. No land would, therefore,
be required for irrigationai purposes. The result would
be that an actual saving °f 8 lacs {the estimate:! price of that
land) ivoitld be effected. I hope this will be a satisfactory
answer to those who think that by permitting the town
to be drained to the Flats the Municipality will be pledged
either to sewage utilisation or to adopt any particular
outfall fpr the sewage. On the contrary, the Municipality
will be free to cast the sewage at whatever outfall they may
hereafter discover to be the best, and at a costless than that
of this project. The only*work that need be suspended in
carrying out this scheme is that of the irrigation pipe which,
if sewage is found valuable, can be laid down to the agri-
. 20
cultural lands in the north, and which, if sewage proves to
be worthless, can be carried to the south.
I must repeat here that I have spoken of the failure of
sewage application, not because there is the least doubt
in my mind of its success, for I have never had any such
doubt at all, but because I wished to argue the question
of the advisability of draining the town towards the Flats
from the point of view of those people who, being opposed
to sewage utilisation, take their stand upon the ground
that the Municipality will commit a grievous error to
adopt Mr. Rawlinson’s Project. The fact being just the
reverse, viz. that the Municipality will be as independent
in their action with regard to the ultimate disposal of the
sewage as they could possibly be.
It is not my intention to argue the question of sewage
utilisation. It would be impossible
Sewage utilisation.
by any process of abstract reasoning
to prove its success to the satisfaction of those who are
opposed to it. It is a matter of practice, not of theory.
If I wished to maintain my point, I could not do better than
describe all the sewage farms which 1 have seen in Europe.
But even if I did this the opponents to sewage irrigation
would probably reply that India was not Europe, and
if I answered that India was better than Europe—that
the conditions of success in India are more favourable than
in Europe—that a greater number of crops can be got off
land in India during the year than can ever be produced
in Europe—that while land in England has to be .drained,
the soil in India thirsts for water—to all this my opponents
could urge that in the absence of actual experiments .with
sewage in India my statements were mere assumptions, and
therefore valueless. The end of such an argument would
simply be a dead-lock.
21
Under- these circumstances it would answer no useful
purpose to enter on this discussion. I am quite willing that
the matter should be decided by direct experiment. There
will be plenty of time before the irrigational part of this
project is carried out for the conversion of the most scep¬
tical.
There is only one argument which I think it necessary
to meet. It may sound very absurd, but it is really the
case that in some towns in England, Rugby for instance,
such a large quantity of food for cattle has been produced
by the help of sewage that there has been the greatest
difficulty in disposing of'it. Croydon being near London,
and having thus a ready market for her produce, has always
been able to sell it, but the town of Rugby could not, for
a fact, get her produce consumed. The town had to pur¬
chase cows and to establish a kind of farm, in order to
dispose of the crops. Now in Bombay this is not likely
to occur. The prices of vegetables and all kinds of garden
produce for human consumption are extraordinarily high,
and especially is this the case in the dry months when water
is scarce. A different state of things will exist when the
sewage is utilised. There need be no fear of overstocking
the markets, for Bombay has a population of nearly a million
people, and many of her wants are badly supplied. Milk
and butter, the two articles that can be produced most
successfully and in the largest quantity by the help of
sewage, are at extraordinary prices. Bad butter is twice as
dear as the best in England, and buffalo’s milk fetches three
times the price of cow’s milk at home. Italian rye grass, of
which I anticipate that from six to eight crops will be taken
yearly off the land in Bombay, will find a ready sale. The
Municipality would require large quantites for their bul¬
locks, of which they keep from three to four hundred
22
pairs. Thus, a direct return would be obtained by the town
for their expenditure on the drainage, and this would
certainly not be the case if the sewage were cast into the
sea.
Before closing this subject, I beg to add that as the
sewage is proposed to be utilised several miles from Bombay,
no possible objection can reasonably be made to this part or
the project, on the score that the inhabitants will be
subjected to a nuisance. Sewage lands, if the irrigation is
carried on properly, give off no noxious gases. It is
difficult to believe this unless one has actually stood in a
sewage field. But those who may differ from me in this
respect could hardly maintain that any mischief will arise
to the town if the sewage is applied to the land so far from
Bombay as is proposed.
The next point which will require consideration is
. , , whether rain and sewage should be
The necessity for the separation °
of ram ami swage. removed by the same channels, or
whether they should be separated. In a Report on the
Drainage of Madras, submitted to the Madras Government
in I860, I endeavoured to show that the expense of
sewering a town in India on the principles.usually adopted
by engineers in England would be enormous. Instead of
repeating the arguments again, I take the liberty of forward¬
ing a copy of that Report, where in pages from 82 to 90
they can be read. Since that Report was written I have
had the opportunity of studying the different systems of
drainage which have been carried out in the countries of
Europe, and I feel more than ever convinced of the neces¬
sity of separating' sewage from rainfall. The London
sewers are built to remove both sewage and rain, and the
rain was taken atone quarter ofan inch in24hours. On these
data the rain amounts to as much as the sewage, so that one
half of each sewer is required for rain and the other half for
sewage.* In Bombay on the 9th of August last, we had
a fall of rain amounting to upwards of 14 inches in 24
hours. Let me, however, take for India the moderate fail
of /> inches in 24 hours. Then, if in London, where the
water supply is above 40 gallons per diem per head of the
population, the rain, with a fall of one quarter of an inch
in 24 hours, is equal to the sewage, it follows that in
Indian towns with a fall of 5 inches in 24 hours and a water
supply of, say, 20 gallons per diem per head of the popu¬
lation, it would be about 40 times as much as the sewage.
So that virtually one-fortieth part only of each sewer
would be required for the sewage and thirty-nine-fortieths
of it for rain. And as falls of rain of 5 inches in the
day do not occur except twice in a year or so, and yet
would have to be provided for, the sewers in Indian towns
to be effectual in removing the rain would require to be
nearly 40 times as large as they need be for sewage
only, and would not have to act to their full discharging
capacity except on the average of once in six months I
In Bombay I would propose to effect a complete separa¬
tion of rain from sewage. The sewers would not conse¬
quently have to deal with a variable quantity of matter de¬
pendent on the amount of rain during the day, but with a
fixed amount of sewage according to the habits of the people.
Thus the normal state of the sewers would be to be
constantly charged with sewage,—constantly acting nearly
to their.full capacity.
Large sewers, when empty, as the sewers of Bombay
would be if they were constructed for rainfall, would during
the dry months be large cesspools. A small body of water
* Vide page 305 of “ Neville’s II)*draulics/’ second Edition,
24
hfls a much greater evaporating surface in a large sewer
than in a little one; more noxious gases escape and the
inhabitants become poisoned with them.
Frortl a pecuniary point of view I do not see how it will
ever be possible for any Indian town to carry out a com¬
plete system of underground drains to remove such heavy
rains as fall in the country. To provide every street in
Bombay with a sewer for rain (and this is the practice in
Europe) would cost the Municipality not less than two
crores of rupees, i.e. £2,000,000. It would simply be
waste of time to prepare a project on such a scale. Indeed
it will be hopeless to expect that any large sanitary works
will ever be carried out in the country, if the usual prin¬
ciples of drainage adopted by engineers in England are
rigidly adhered to. The mere fact that the London Drain¬
age Scheme is based oh the assumption that only two-fifths
of an inch of fain falls over the town in 8 hours should
show the aspect of the question in its true light as soon as
we come to apply the principles to Bombay, where only
three months ago there was a fall of rain over the town
amounting to more than 14 inches of rain in 24 hours. It
cannot, moreover, be urged, as it may be in England, that
all heavy storms are merely local and therefore should not
be considered in drainage schemes. Every one who has
been in India but a few years knows that one of the great
characteristics of the monsoon is that it is never confined
to one small locality. When the monsoon breaks over a
town it is almost certain to be raining equally hard not only
over the entire area of it but over the surrounding country
for miles distant.
Under these circumstances I maintain that the only way
in which it will be possible to drain
The proposed drainage system A
for rain water. Indian towns of heavy rainfalls, so as
25
to bring the cost within the means of Municipalities, will
be by the help of a few main underground channels, and
by dispensing with these works in all the minor streets—
letting the water escape from them along the surface of the
roads. I believe Bombay has already a sufficient number of
underground drains for the removal of rain. All that I
propose to do is to extend the main drain to the Pumping
Station at Love Grove.* This main drain will actually be
capable of removing more than 14 inches of rainfall over
the town in 24 hours, and the engines on the other hand
will be able to pump nearly the whole of this into the sea
during the same time. .Thus the state of things which
occurred on the 9th of August last when some of the houses
in the town were three feet under water will be rendered
impossible. In fact the town will probably never be under
water at all, and this irrespective even of tides.
The main drain, moreover, would have an overflow on to
the Plats, so that if the water beat the engines, or, in
other words, if there were at some very critical period of
the storm more water brought down to the station than
the engines could deal with, the overflow would come into
operation and the surplus water would be passed on to
the Flats, to wait there till the tide went down, when
the sluices would be opened and it would run into the sea.
Should there be any water in the town which could not
enter the main drain, on account of the latter being quite
full, such water would pass on to the Flats, as it now does,
by the natural valley line. But such a case is not likely to
occur, and I would not therefore recommend the construc¬
tion of any new large drains for rain water till the effect of
the proposed works can be judged of. I believe the town
* Vide Plans Nos. 1 and I.
20
will be perfectly dry, even when 14 inches of rain fall in
24 hours. For greater storms, I think, it will be admitted
by all, I could not justifiably provide. The emergency
might not occur in two or three generations.
i Only to give an idea of the cost of large sewers I may
mention that one of the heaviest items in the estimate for
the proposed works is the continuation of the present main
drain, 20 feet wide and 10 feet high, to the pumping station.
The distance is rather more than a mile and a half, and
the cost will be about eight lakhs of rupees. A few works
of this nature would swell the cost of any project to such
an extent as to render its practicability out of the question.
I do think they are uncalled for. Let as much rain as
possible escape naturally to the Flats to be discharged into
the sea by the sluices, and let only so much be pumped as
will keep the town dry.
It should be borne in mind that every extension of the
town and consequently of the sewerage works will render
the treatment of floods easier. A greater number of en¬
gines will have to be erected for the increased amount of
sewage, and these, at times of emergency, can be employed
for the relief of the town and island from floods. Thus
as the town grows older more and more power will be
brought to bear for the removal of rainfall. The project
will become more perfect, and a flood be ultimately ren¬
dered quite impossible.
If it then be decided, as I propose, to separate rainfall
from sewage, and to treat the two differently, the sewers
and pipes for the removal of the latter will be of reasonable
dimensions. The main sewer, where it is largest, will be
only 8 feet 6 inches high by 5 feet 8 inches wide, and it
will be of this size for only two-thirds of a mile. By far
the larger portion of the island may be drained simply
â– 27
by earthenware pipes. On the accompanying map* the
directions, sizes, slopes, and other information regarding
the works may be obtained. The sewers have been put at
such a depth below ground as will give slopes to the
earthenware pipes which will keep them clear of deposit.
•
There is a question here which demands attention. It
has been maintained by some that the sewage of Indian
towns will always be thicker than that of towns in
England, because rain is admitted into the sewers of the
latter, while, even if it were so into those of the former,
still from the long continuance of dry weather there would
be many months of the year when the sewers would only
be filled with the waste water from the houses. Now
though it is quite true that the more water there is the
more liquid will the sewage be, still it must not be for¬
gotten that the addition of rain to sewage entails also the
addition of the very matter with which most sewers are
found to be choked up. It is not light substances such
as house refuse of all kinds of which the deposit consists,
but it is almost entirely composed of sand, gravel, clay,
&c., and these are washed into the sewers by the rain.
Light substances float on the surface, and thus pass on to
the outfall, while the road detritus sinks at once to the
bottom and accumulates there. I feel certain, therefore, that
there will be very few obstructions in the Bombay sewers
as compared with those which occur in the English ones.
However perfect works may .be in theory, something
will occasionally happen to prevent
The cleansing of the sewers. i /» . . * ..
them from acting properly in practice.
Provision should, therefore, be made, not only for as-
* Vide Plan No. 1.
28
eertaining when an obstruction occurs in a sewer, but also
for removing it. In England the usual practice is to put
manholes at about a hundred yards apart. In Bombay I
propose to put them only 200 feet apart. The facilities
for examining the works under ground will be much in-
creased. By the help of a lamp, the position of an ob¬
struction will be easily ascertained, and in order to remove
it flushing will have to be used.
For the sewers I would employ the same means of flush¬
ing as that adopted in England where the practice is to
form a temporary dam in order to let the water collect
above the obstruction, and, when a sufficient body of water
has been obtained, to remove the dam suddenly. I think
this will answer every purpose in Bombay. But for the
earthenware pipes I propose to make arrangements by
which every manhole may, as occasion demands, be con¬
verted into a flushing reservoir. Suppose there is an
obstruction in a pipe, then the mouths of the pipes at the
bottom of the manhole above the obstruction will be closed,
and the manhole filled with as much water from the nearest
Vehar main as may be considered necessary. The mouth
.then of the pipe to be flushed will be suddenly opened by
a lever from the surface of the street and the water will
rush with great velocity to remove the obstruction. I feel
confident that very few obstructions will ever occur which
cannot be removed by these means. Should it, however,
become necessary at any time from the fracture of a pipe
or other accident to dig down to the work, the proposed
short distance between every two manholes will enable the
workpeople to ascertain wflth great precision the exact
position where the damage has occurred. Consequently
no labour will be thrown away or useless expense incurred
in digging up more of the street than necessary.
29
There is no doubt that the perfect ventilation of sewers
has not been effected up to the present.
Ventilation. A A
The charcoal system is, however, ad¬
mitted by most engineers to be the best. Until some more
successful plan is discovered, I propose to disinfect the
Bombay sewage by charcoal ventilators, one of which will
be put down at every manhole.
The house drainage of Bombay will not be nearly so
difficult as that of other Indian towns.
House Drainage.
Between every two houses in Bombay
there is usually a narrow open passage for drainage. I
propose to lay the new house drain under this passage, and
to connect it, at one end with the sewer in the street, and
at the other with the pipe which now brings down the
waste water from the upper stories of the house. In those
few cases where “ back drainage” can be adopted, this
'should of course be done.
Wherever water is used in a house I should insist on a
proper sink, with perforated holes in it and with a syphon
trap, being put down. .This would effectually prevent
large substances passing into the pipes to choke them up,
and would at the same time keep the noxious gases from
entering the rooms. A ventilating pipe connected with
the house drain, would be carried up above the roof of the
dwelling. All house drains, without exception, would be
six inches in diameter.
I have some difficulty in approaching the Question of
the removal of excreta. This por-
The removal of excreta. A
tion of the drainage of a town is
so intimately connected with its water supply that it is
impossible to treat it successfully by itself. The fact is
that drainage and water supply are really one question
only. To separate the two by considering each apart will
30
render both defective. Yet if I touch on the subject of
excreta I shall have to do so without a sufficient knowledge
O
of the intentions of the Municipality regarding their future
water supply of Bombay. There is, no doubt, a scarcity
of water at present. The town should not rest contented
with a supply of less than 30 gallons per diem per head of the
population. When this supply is obtained I would re¬
commend the introduction of water closets. I must guard
myself against the supposition that these closets would
be similar to those used in England. Such closets would
not at all suit the habits of the people. I would have
closets of a much simpler kind, ,and so constructed as not
to be liable to injury from those who use them. 1 should
hope, too, that the habits of the people, under better
sanitary regulations, would ultimately lead them, though it
might be very gradually, to see the advantage of keeping
their closets clean, and that the introduction of the •
European water closet, at all events among the better
classes, would be rendered possible.
Of course it would be out of the question to put up
closets at present while the supply of water to the town is
so limited. Abundance of water for closets is a sine qua
non, but I think a lengthened discussion of the subject at
present would be only premature.
It really does not matter for the purposes of this project
how the excreta may be disposed of. If it is found best
not to let it go into the sewers, the sewers will still have
their work to do, viz. the removal of all the waste water
in the town. But on the other hand if it be decided to
discharge the excreta into the sewers, the sewers will
convey it away out of the town in a few hours, and it
will be utilised on land.
31
All open drains will 1m done
away with.
Under the new state of things that abominable system
of opening the sewers, which at
present exists in all parts of the town,
will be entirely done away with. There will be no matter
in the sewers that will require removal. Everything will
be carried to the pumping station, pumped up there and
sent on to be utilised on land. Nor will there be any
necessity to continue the present system of open drains. I
think all sanitarians will agree with me when I say that the
chief cause of disease at present in Indian towns arises
from our letting the waste water run in open channels.
It is impossible to keep tl^ese drains clean for the simple
reason that it is impossible to prevent people throwing
their rubbish into them. It is the action of the water on
the vegetable and animal matter in* the drains that gives
rise to the foul smells in the streets. Everywhere around
one decomposition is in rapid progress. Under the new
system there will be no open drains and the foul substances
which at present ferment under the action of water must
at the worst lie in the street, where they will either soon
be converted into dry rubbish by the action of the sun, or
be removed by the scavenging department to the street
receptacles for ’filth. The heat of the sun deprives all
substances of moisture—in fact dessicates them, and it is
well known that matter in this form is comparatively
harmless, whereas the same matter lying in water becomes
a constant source of disease.
I would have all the open drains gradually broken up
and filled in with road material. At the same time the
section of the streets would be improved. They could not
be of a better form than that already adopted in many parts
of the town where the sides of the road are finished off
32
with a slight scoop, and a curb stone separates the carriage
road from that for pedestrians.
The rain which falls on the town will escape in this
way. It will first run along the sides of the roads until it
enters a street where there is one of the present under¬
ground drains, into which it will pass. It will then flow
on to the present main drain which will carry it to the
Flats, or the pumping station (as the occasion may require),
and will there be either pumped into the sea or allowed to
escape through the sluices. The main drain, as I have
already shown, will be capable of removing more than 14
inches of rain falling on the town in 24 hours.
At present the Municipality spend about a lakh of
Rupees a year in cleaning the drains. Under the new
system this sum .will nearly all be saved. I have not, how¬
ever, credited myself with the saving, as I propose that,
this money, which represents a capital of about 16 lakhs of
Rupees, should be devoted to filling up the drains and im¬
proving the roads. Should a drain for rain water be
required in some particular street hereafter, it could be
built when found necessary just below the surface of the
road, but I do think it would be mere waste of money to
erect such works at present.
Having now completed the general description of the
proposed project, it is necessary that I should enter on
some particulars in connection with the works themselves.
The only part of the thickly inhabited portion of the
Particular description of seme SOUtlldU half of tile Island which Will
of the works. . .
not be drained bythis scheme is Colaba.
It is a small locality, and the population can never be
great. It would not be worth while to lay down an
expensive sewer for so few people, but if this should be
33
required, it could be done simply by extending the main
sewer to the south. The main sewer,
The main sewer.
as proposed at present, will start from
the Fort with its invert at 53 above datum. After re¬
ceiving the sewage of this neighbourhood, it will cross
the Esplanade, along the road west of the Dhoby lines,
and then enter the town. It will continue its course along
the following streets : Shaik Memon Street, Bholeshwar
Road, Ardasheer Dady Street, Ivhetwady Back Road. It will
then cross Grant Road and Bellasis Road, and run direct
to the Pumping Station, which will be situated close to the
present one at Love Grove., At this point the main sewer
will have its invert at 37 above datum.* At the Fort
with a slope of 4 feet to the mile it will be 3 feet 9
inches high by 2 feet 6 inches wide, and it will gradually
increase as it passes through the town till it reaches the
Flats, where, with a slope of 2£ feet per mile, it will be 8
feet 6 inches high by 5 feet 8 inches wide. Throughout its
course it will be egg-shaped. There will be two branch
sewers required, f and each will be
Branch sewers. x
3 feet 9 inches by 2 feet 6 inches and
have a slope of 4 feet per mile. The first will start from
Mazagon, and join the main near Mombadevy Tank. The
second will start from the Parell Road, near Sindalpara,
and will join the main on the Flats. The more important
streets running perpendicularly to the main will be furj-
nished with 12 inch earthenware pipes, and all other
streets with 9 inch pipes. Both the main and branch
sewers will be built of the best brick.
The sizes of the sewers have been regulated thus. Each
sewer will discharge rather more than the sewage of the
* Vide Plans Nos. 1 and 3.
f Vide Plan No. 1.
34
inhabitants living on the area which drains into it. Allowing
for a much more abundant water supply than Bombay has
at present, the sewage is taken at 20 gallons per diem per
head, and half this quantity is supposed to run off during 8
hours of maximum flow. The number of people living in the
thickly populated parts of the town has been ascertained,
as well as this could be done, from the last census returns*
and the possible future population on the thinly inhabited
areas is taken at 500 souls per acre.
The power of the engines has been calculated in this
way. The population has been taken
The Engines. x x
at 1,000,0.00, and the water supply at
20 gallons per head per diem, half of which has been assumed
to run oif during 8 hours of maximum flow. In order
to send the sewage to a distance to be utilised it will be
necessary to pump it about 50 feet high. With this lift
about 315 horse-power nominal will be required. Accord*-
ing to the usual plan adopted in water works I propose to
have three engines each of half the actual power required,
or say three engines of 150 horse-power each. Two would
be ordinarily at work, and the • third as a reserve in case
of accidents.
I would have two of the engines of the kind known as
rotatative expansive double powered condensing engines.
The third engine would be a high pressure one, capable in
•an emergency of being worked up to two or three times its
nominal power. This engine would work a large centri¬
fugal pump and would be the principal one employed on
the duty of relieving the town of floods. The average lift
would be 8 feet. Moving at a high speed the pump ought
to throw a large quantity of w’ater. In place of one high
* The density of some of these is extraordinary—700 to 800 souls per
acre. The average density is over 600 per acre.
35
pressure engine it may hereafter be found more convenient
to have two, each of 100 horse power nominal, but this is
a point of minor importance at present, and need not be
entered into further. The length of stroke, size of pumps,
&c. had best be decided upon while the detail plans of the
works are being prepared. Thei’e should be a filth hoist
and a number of other arrangements made, similar to those
carried out at the large sewage pumping stations of
London. All these details will have to be carefully at¬
tended to before the engines are ordered.
As fast as the sewage is pumped up it will be carried by
The irrigational part of the
project.
a 4-foot cast iron main to the irrigation
lands, where it will be let on to the
fields by the help of sluices. If it could have been done
I should have preferred to build a sewer above ground as
recommended by Mr. Iiawlinson in place of laying down
a- cast iron pipe as proposed by me. But I found that in
order to construct such a sewer I should have to raise an
embankment over parts of the island more than 30 feet
high.
In fact the levels of the ground are so unfavour¬
able for a high level irrigation sewer that I am certain
Mr. Rawlinson will agree with me in this departure from
his suggestion when he learns why 1 have adopted the
cast iron pipe. I will not here enter on the question as
to the best mode of applying the sewage, because before
the day comes for doing so there will be plenty of time to
make experiments, and these will be a safer guide than any
instructions I could give, which would be based on my
experience of sewage farms in Europe only.
The present main drain is to be continued from where it
stops now near Bellasis Road down to
the pumping station.* Its form will
Continuation of the present
main drain.
* Vide Flans Nos. 1 and 4.
36
be altered in order to render the work less costly. It will
be nearly semicircular, the diameter being 20 feet. It
will have a slope of about 4 feet per mile, and enter the
pumping' wells at the same level as the new main sewer.
The discharging power of the new main drain will be fully
equal to that of the old. As it will be required for
rainwater only, I propose to build this work with rubble
stone.
The proposed sluices at Love Grove, Worlee, and
giu.fes Daravee,* each having a waterway of
120 feet in length, may be of the
kind now in use, which seem to answer very fairly.
In preparing the detail plans it will probably be found
better to make the sluice at Daravee, with a waterway of
about 80 feet, and each of those at Love Grove and Worlee
with a waterway of 140 feet,—keeping the total waterway
the same as before, viz. 360 feet long. When more levels
are taken over the island the areas that will drain through
each sluice can be calculated, and the length of the sluices
regulated thereby.
The entire cost of this project is estimated at 75 lakhs of
Rupees. The details of the estimate
Cost of the Project. - • i * ,. ~r
may be seen m the Appendix. I have
gone as carefully into the subject as I possibly can, and I
believe if there is any error in the estimate, it will be
found to be on the side of excess.
I may perhaps go over some of the more important items
for the satisfaction of those who may
The Rates for work. .
not care to examine the detailed
statement. Brickwork for the sewers has been taken at
Rs. 90 per 100 cubic feet, excavation at Rs. 12, and rock
* Fide Plan No, 1.
cutting at Rs. 40. Twelve-inch pipes are calculated at
1 Rupee 6 annas, and nine-inch at 14 annas per foot run.
These are higher prices than the Municipality have paid
up to the present.. The excavation for the street drainage
has been taken at Rs. 8 per 100 cubic feet. The cut¬
tings will not be so deep as those required for thesewers.
The engines have been estimated at 1,200 Rs. per horse¬
power, and a lump, sum of 3,00,000 Rs. has been put down
for the engine and boiler houses.
The irrigational part of the scheme will consist chiefly
in the laying down of cast iron pipes, which have been
calculated for at Rs. 120 the ton. About 8 lakhs has been
allowed for the purchase of land for sewage irrigation,
which lies several miles from Bombay.
The rubble for the Main Drain has been taken at Rs.
50 per 100 cubic feet.
Each sluice, with a waterway of 120 feet in length, has
been estimated to cost l^dakhs.
Ten per cent., or nearly 7 lakhs, has been added to the
total cost of the project to allow for all.contingencies.
I am told that the rates I have taken are unnecessarily
high. If I chose therefore to make the project more
attractive I could do so by reducing the estimate to about
Rupees 68,00,000. I prefer however to let it stand as it is.
I would rather err in having exaggerated than in having
under-estimated the cost.
This project will no doubt be compared by many people
with those which have already been
Summary of Project. ... .. 1 t
submitted to the Municipality. In
order to form a fair judgment in the matter it should
be borne in mind what is intended to be done by each. I
believe this will be fo.und by far the cheapest scheme
yet proposed for the drainage of Bombay, but I should
be the last to urge that it should be adopted merely
on that account. Of course every project must be looked
at from a pecuniary point of view. The cheaper it is the
more advantageous must it be for the inhabitants. But
mere cheapness should never be its sole recommendation.
Its sanitary and engineering advantages should also have
due weight. The following are the main objects to be
effected by this scheme. I beg those who may have done
me the honour to read this report to compare these objects
with those contemplated by other projects :—■
lsf.—This is not a project for main drainage only but for
the entire drainage of Bombay from rain and sewage,—for
all works complete nearly up to the door of every house.
2nd.—The town is to be immediately relieved of floods
even during storms when 14 inches of rain fall in 24 hours.
I believe no city in Europe, and if I add in the world
I shall not perhaps be wrong, has yet attempted to deal with
a rainfall approaching these limits.
3rd.—The entire %island is to be relieved of floods after
similar storms of 14 inches of rain in the day, so that within
24 hours after the close of the storm there shall be no swamps
to be found anywhere.
4th.—From being a foul and pestilential swamp, a re¬
ceptacle for the filth of the town, a constant source of
disease to the inhabitants, and the greatest nuisance in
Bombay, the Flats will be converted not only to a useful but
even to a healthful purpose.
5th.—That which gives Bombay its chief importance,
and must ultimately make her the capital of India—her-
magnificent harbour—will be preserved from sewage pollu¬
tion. Thus the drainage of the tojvn can never in anyway
detract from its maritime advantages.
39 •
6th,—Instead of being thrown away as worthless the
sewage will be utilised on land. Thus, what is rightly
termed a “ source of wealth” by the leading scientific men
in Europe will be secured to the inhabitants.
1th.—In whatever direction the town may spread the
new districts can be drained so that the works required for
them will fit in at once with those already proposed for the
present town. Thus Bombay, increase as she may, will
always be drained on one comprehensive plan and not by
a series of patchwork systems, each unconnected with
the others.
8th.—The Municipality 0will have the sewage so com¬
pletely under command that they will be able to utilise it as
recommended by Mr. Rawlinson, or to discharge it into the
sea at any point on the coast of the island at a cost not ex¬
ceeding that of this project. Thus the disposal of the sewage
will in no way affect the works of drainage and sewerage.
If these are the best in themselves that have yet been pro¬
posed for the town, they need not be delayed on account of
any doubts there may be in the minds of the Municipality
with regard to the success of sewage utilisation.
In conclusion, I beg to add that no one can be more sen¬
sible than I am how imperfectly I have been able, in the
short time I have been engaged on this work, to do justice
to Mr. Rawlinson’s scheme. The more the general princi¬
ples of that scheme are considered the greater conviction
will they carry to the mind that Mr. Rawlinson’s proposi¬
tions are the best that have yet been made for the drainage
of this important town. Now that the scheme for
utilising the London sewage has been temporarily given up
for want of funds in consequence of the depressed state of
the money market, I believe that if this project is quickly
carried out, Bombay will be the first city in the world with
a population of a million inhabitants that will have utilised
her sewage on a systematic plan. In fact she will have set
Europe an example in the adoption of those principles
which, although they have been advocated for years by the
leading engineers of England, and by the most scientific
men on the Continent, have yet never been fully acted*
upon in any one city in the world.
I beg to thank all those who have assisted me with
information or suggestions in the preparation of this project,
and especially Mr. Thwaites, C.E., the present Resident
Engineer, Bombay Main Drainage, whose acquaintance with
sewerage works generally, and with those of Bombay in
particular, has been of great service to me.
H. TULLOCH,
Captain Royal Engineers.
APPENDIX I.
• —<x£$eJCX>
ESTIMATE OF COST OF PROJECT.
SEWERS.
Brickwork.
No. of Cabio -j- _4 .. Cubic feet
Sizo of Sewer. Thickness, feet in one . xl of brick-
c , m ieofc. .
root run. work.
f3
ft.
9
in.
X
2
ft.
6 in. ..
9
in.
.. 9-2 .
. 0,300
.. 57,960
6
4
ft.
6
in.
X
3
ft.,
• .
9
in.
.. 107 .
. 2,520
.. 26,964
d
K
O
ft.
9
in.
X
3
ft.
10
in...
9
in.
o
.. 13-2 .
. 1,943
.. 25,648
6
ft.
6
in.
X
4
ft.
4
in. • •
14
in.
.. 24-5 .
. 4,305
..105,473
3 ]
i 7
ft.
6
in.
X
5
ft.
• ♦
14
in.
.. 28-8 .
. 2,730
.. 78,624
8
ft.
X
5
ft.
4
in...
14
in.
.. 30-5 .
. 5,355
..163,328
. I8
ft.
6
in.
X
5
ft.
8
in..*
14
in.
.. 32-G .
. 3,800
..123,880
so
1J
rs
ft.
9
in.
X
2
ft.
6
in.. ♦
9
in.
.. 9-2 .
. 7,775
.. 71,530
P1
L3
ft.
9
in.
X
2
ft.
6
in...
9
in.
.. 9-2 .
. 6,510
.. 59,892
713,299
or say 7,133 brasses* X 90 Rs. each = Rs, 6,41,970.
Excavation.
Feet run.
Width in feet.
Depth in feet.
Cubic feet.
**
6,300
.... 5
18 =
567,000
2,520
.... 5-5 ....
20 ==
277,200
o
.2
1,943
.... 6-3 ....
21 =
257,059
d <
4,305
.... 7-7 ....
18 =
596,673
*3
k«—<
2,730
.... 8-3 ....
16 =
362,544
i«q
5,355
.... 8-7 ....
13 =
605,651
3,800
.... 9
11 =
376,200
1 1
r
4,575f
.... 5
15
343,125
11
sq
0,510
.... 5
! ! =
455,700
Total....
3,841,152
or say 38,112 brasses X 12 Rs. each = Rs. 4,60,94 k
* ‘ Brass’ is a local term for 100 cubic feet.
f The remaining length, viz. >3/200 feet, is calculated for in rock cutting,
6 D
42
Rock Cutting (Maxagon Branch Sewer).
Feet run. Width in feet. Depth in feet. Cubic feet.
3,200 .... 3 .... 23 = 220,800
or 2,208 brasses X 40 Rs. each. = Rs. 88/320.
Note.—The lengths of all the Sewers will be found on the ground
from 5 to 8 per cent, under these calculated for above. The cost of
the Sewers therefore is, I am positive, over estimated.
STREET DRAINAGE.
Rs.
15 miles of 12 inch earthenware pipe or 79,200 feet
run X 1 Rupee G Annas per foot. = 1,08,900
55 miles of 9 inch earthenware pipe or 290,400 feet
run fX 14 Annas per foot.. = 2,54,100
70 miles of excavation, 3 feet wide and 9 feet deep,
or 9,979,200 cubic feet, at 8 Rupees per brass .. = 7,98,330
Total... .Rs. 11,61,336
MANHOLES.
2,055 Manholes at 200 Rupees each complete.... =Rs. 4,11,000
Note.—A great deal of the stone obtained in excavating for the
sewers, pipes, sluices, &c., can be used for the Engine Houses, Man¬
holes, Main Drain, Sluices, &c.
It is probable that some valuable lime kunkur will be found in
excavating; for the Sewer and Drain on the Hats. This also can be
used on the works.
PUMPING STATION.
Rs.
Two Condensing Engines, each of 150 Hoi'se Power
(nominal), at 1,200 Rs. per Horse Power = 3,GO,000
Two High Pressure Engines, each of 100 Horse
Power, at 750 Rs. a Horse Power = 1,50,000
Engine and Boiler House, &e., say „ 3,00,000
Total..Rs. 8,10,000
43
EXTENSION OF PRESENT MAIN DRAIN.
Floor—8,500 feet long, 20 feet wide and 1 foot thick, Rs.
or 170,000 cubic feet of stone-flooring, at 100 Rs.
per brass 1,70,000
Arch—8,500 feet long, an average thickness of 2| feet and
a mean length (arch) of 43 feet, or 913,750 cubic
feet of stone rubble, at 50 Rs. per brass. 4,56,875
Excavation—8,500 feet long, 26 feet wide and 10 feet deep,
or 2,210,000 cubic feet, at 6 Rs. per brass .. 1,32,600
Manholes at 300 feet apart 6,000
Total.... Rs. 7,65,475
SLUICES.
Three sluices, each 120 feet long, say at Rs. 1,50,000 each.Rs. 4,50,000
OUTLETS.
Outlets to Sea from Pumping Station Rs. 30,000
* SEWAGE IRRIGATION.
CAST IRON PIPES, &C.
6,006 tons of cast iron pipe, 4 feet diameter, at 120
Rupees per ton delivered on works 7,20,720
Laying and jointing the same.. 1,05,600
Excavation for same, 760,320 cubic feet, at 6Rs. a brass. 45,619
1,610 tons of cast iron pipe, 2ft. diam., at 120Rs.perton. 1,93,200
Laying and jointing the same 49,280
Excavation for same, 221,760 cub. ft., at Rs. 5 per brass. 11,088
517 tons of cast iron pipe, 3 ft. 4 in. diameter, at 120
Rs. per ton 62,040
Laying and jointing the same , .... 10,590
Excavation for same, 65,340 cub. feet,‘at 5 Rs. per brass. 3,267
31 Ortons of cast iron pipe 15 in. diam. at 120 Rs. per ton. 37,260
Laying and jointing the same 15,400
Excavation for same, 79,200 cub. feet, at 5 Rs. per brass. 3,960
Stop valves and sluices 11,070
Total.... Rs. 12,69,094
Land.
Land for sewage irrigation 7,20,000
44
Sewers
TOTALS.
lls.
f Brickwork 6,41,970
^ Excavation 4,60,944
LRoek-Cutting 88,320
f 12 inck Pipes 1,08,900
Street Drainage 9 do. do 2,54,100
^Excavation for Pipes .. 7,98,336
Manholes
fEngines 5,10,000
Pumping Station. Engine House, Boiler
House, &c. 3,0Q,000
Extension op Main Drain
Sluices
Outlets to Sea
Sewage utilization
f Pipes and Valves, &c. . 12,69,094
t Land 7,20,000
Add 10 per cent, for contingencies
Grand Total.... llupees
Us,
11,91,234
11,01,336
4,11,000
8,10,000
7,65,475
4,50,000
30,000
19,95,094
♦
68,14,139
6,81,414
74,95,553
or say 75 lakhs ofKupees.
APPENDIX II.
REPORT
ON
Me. SOWEEBY’S MEMORANDUM
ON THE
DRAINAGE OF BOMBAY
Mr. Sowerby^s Memorandum consists principally of a criticism on
Mr. Rawlinsoffis Project, and of a short proposition of his own for
the drainage of Bombay. As the Report which accompanied the
Project which I have already submitted to the Municipal Commis¬
sioner discusses Mr. Rawlinsoffis scheme fully, I do not propose to
go into that subject again here. I shall, therefore, confine myself to
a consideration of Mr. Sowerby*s system of drainage.
Mr. Sowerby ^proposes that “ in order to meet the peculiar cir¬
cumstances of Bombay, with its heavy rainfall at certain periods, it
would be advisable to have a large and open canal carried along the
middle of the island from Back Bay to Mahim. This canal should
communicate with the sea at Back Bay and Mahim, and have two or
three branches connecting it with the harbour at various suitable
points. It should be of considerable width, say 150 to 200 feet, and
of depth enough to admit of laden barges forming a canal of naviga¬
tion, the excavation to afford sufficient material to raise and reclaim
the adjacent lowlying ground on cither side, so as in a great measure
to repay the cost of formation. This canal would form a perfect
catchwater drain for all surface rain water, and to prevent its be¬
coming stagnant by a proper arrangement of sluices at each end at
the branches a continuous stream could be kept passing though it.
7i>
Mr. Sower-
by’s system of
drainage.
His alterna¬
tive system.
Objections to
the alterna¬
tive system.
' 46
Alongside of ttliis canal should be two intercepting sewers of suffi¬
cient capacity, one on each side of the canal. Two small sewers
would be better than one large one, owing to the expense of
construction and the convenience or forming junctions. The whole
of these sewers should be as low as possible so as to get a natural
outfall towards the north, and' to take advantage of the head of
water in the canal for the purpose of flushing if need be.”
Mr. Sowerby adds that “ if it was found necessary to let the
sullage fall into the sea, as it would probably be, then at about half
tide, or earlier, a body of water could be obtained from the canal and
basins attached to it to flush the sewage rapidly away.”
He then goes on to say that u an alternative plan would be to
have no intercepting sewers alongside the canal, but to have the
main drains all running at right angles to it and emptying them¬
selves into the harbour at one side and the sea at the other, something
similar to the plan proposed by Mr. Tracey, using the water from
the canal for the purpose of flushing the drains to the right and left.
This plan, however, would most probably not be so good as that of
carrying the whole body to the north along side the canal, there to
be disposed of for irrigation purposes if possible, or swept iuta the
sea at a point far a#ay from Bombay.”
In making all these propositions I can hardly think that Mr.
Sower by can have had the advantage of reading the previous corre¬
spondence that has taken place regarding the drainage of Bombay,
lie has opened questions which for some time have been considered
as settled, and in opening them he has not answered the objections
â– which have been already brought forward against his propositions.
It would take me a long time if I attempted to go minutely into the
matter, and it would hardly bo worth tho while, especially as the
objections to tho main features of the scheme are themselves over¬
whelming.
I will first take Mr. Sowerby’s (C alternative ” system of drainage.
The late Mr. Tracey, after much consideration, condemned every
portion of the coast of the island for the purposes of an outfall ex¬
cept the harbour. As far as I can gather from the records, and
from the opinions of Engineers in Bombay, there seems to be an
almost unanimous opinion, in which I agree, that the sewage of
Bombay should not bo discharged either in Back Bay or on the
western coast of the island. The reasons are so obvious. The
prevalent winds are from the west, and experiments have shown
47
that the sewage would be <®st back on the foreshore* The effect
of sewage lying on an open beach exposed to the action of the sun
would certainly be anything but pleasant for the inhabitants. Yet
Mr. Sowerby distinctly proposes that part of the sewage be discharged
on the western coast of the island. There can be no possible ob¬
jection to anybody making this proposition clenovo, but whoever does
so should at least answer all that has been previously urged against it.
Similarly Mr. Sowerby proposes to discharge part of the sewage
into the harbour without at all specifying the exact positions of
the outfalls. Now the great point of dispute between Mr. Tracey
and Mr. Aitken is as to the precise locality of the outfall. They
are both agreed that the sewage should be discharged into the sea
on the harbour side of Bombay, but while Mr. Tracey advocated a
more northern outfall, Mr. Aitken, on the contrary, maintains the
advantages of its being placed at Colaba. In recommending his plan
of drainage Mr. Sowerby is bound to answer Mr. Onniston’s and
Mr. Aithen's objections to the northern outfalls, before he can expect
the public to consider the. subject. It is difficult moreover, to
criticise Mr. Sowerby’s scheme because some of the main features
even are so ill-defined. It seems to me clear, however, that his
outfalls would be situated further north than <£ven Mr. Tracey’s.
Therefore Mr. Ormiston’s and Mr. Aithen’s objections would apply
with still greater force to them. I need hardly say that I am utterly
opposed to the harbour being polluted with sewage.
I will say no more of the “ alternative” plan of drainage, as it does
not meet with even Mr. Sowerby’s unqualified approval. Most of
the objections, moreover, which I shall have to urge against his other
system will bo applicable also to this one.
As far as I can understand the object of the proposed canals, the The system
advantages which Mr. Sowerby thinhs he will obtain by them will shicrod^ener^
be these—1st, they will be catchwater basins for all the rain falling aI]y*
on the island; 2ncl} they will be flushing reservoirs to keep the
sewers clean; and 3rcl, they will be useful for purposes of navigation.
Now if they are to be catchwater basins it is evident that they
must be put at such a level that all parts of the island will be able
to drain into them. Taking datum line at 50*00* below mean sea
level, parts of the flats stand at 48*00 above datum. Therefore if the
* To reduce these levels to Colonel DeLisle’s datum add 29*70 to each.
48
flats are to be drained into tlie canal, tli? surface of the water in the
latter must not be above 48*00 Le. about 2 feet below mean sea
level. But this would give us, as I will show, no flushing power
for the sewers that "would be worth having.
According to Mr. Sowerby the sewers are to be put aas low as
possible/” Now it would be of no use to put them below low -water
of spring tides (42*75 above datum) as no extra depth beyond that
limit would give any increased flushing power from the canal. The
surface of the canal being, therefore, fixed at 48*00 and the inverts
of the sewers at 42*75 above datum, the utmost head of water for
flushing purposes will be 5| feet, and this head will be obtainable at
spring tides only.
During neaps the tide does not fall below (45*00) above datum,
and consequently the head of water for flushing purposes would
amount to the difference between the level of the surface of the
canal (48*00) and low water of neap tides (45*00) or 3 feet only.
It will thus be seen that the available head of water by which the
sewers are to be kept clean will be 51 feet during spring tides and
3 feet during neaps .Let us see what this will amount to practically.
The sewage is to be discharged into the sea at Mahim, and the
sewers are to be built one on each side of the canal, -which must run (as
proposed by Mr. Sowerby) from Back Bay to Mahim, a distance of
6 miles. If we divide the length of each of the sewers (6 miles) by
the available head, the flushing power will be equivalent to a fall of
not quite one foot per mile duifing spring tides, and to only half a
foot per mile during neaps. The sewer which Mr. Aitken proposed
to lay down to Colaba was a circular one of 10 feet in diameter and
he gave it a slope of 2 feet per mile. The main sewer proposed by
me has a slope which varies from 4 to 24 feet per mile. Mr. Sowerby's
sewers, therefore, with the help of the canals, would not have even
half the slope of Mr. Aitken^s sewer, and not one-third the slope of
mine. *
Little as the flushing power i3, I have put the case for Mr. Sowerby
at its best—better than he has put it for himself. For I have sup¬
posed that the sewers are flushed at low water only when there is
the greatest possible head available. Mr. Sowerby, however,
suggests that the flushing is to take place “ at about half tide, or
earlier.” If this were done the available flushing power would be
only half of what. I have shown it can be under the most favourable
49
circumstances. In other words this would be equivalent to a fall
of not 6 inches per mile during .spring tides and of just 3 inches
per mile during neaps !
The truth is that if the object is to secure the greatest possible
flushing power it will be necessary to put the canal very much
higher. The highest it could advantageously be put would bevwith
its surface at high water of spring tides, i.e. at 57*25 above datum.
In this case the available head for flushing the sewers would amount
during spring tides to the difference between high (57*25) and low
water (42*75) of springs, or to 14| feet, and during neaps to the
difference between high (55*00), and low water (45*00) of neaps,
or to 10 feet. But as the sewers are to be flushed at half tide, half
these heads only will be practically available. Thus, under the very
best conditions, the sewers will only have a fall of about 11 feet
per mile during spring tides and of 10 inches per mile during neaps.
Unfavourable as these heads are, let me show at what cost they
must be secured. The canal would stand many feet above the
floods on the flats, and therefore would be perfectly useless as a
catchwater basin* If the embankments moreover, were not always
watertight the flats would be constantly liable to inundations.
It would be only fair to suppose that in preparing his scheme
Mr. Sowerby was not aware how very unfavourable the levels of
the different parts of the town and island are for canals. He has
put himself on the horns of a dilemma from which it is impossible
to extricate himself without abandoning some of his main principles.
If the canal is to be a “ perfect catchwater basin for all surface
rain water,” then the level at which it must be put will render it
nearly useless for the purpose of flushing the sewers. And if, on
the other hand, it is put at such a level as to secure the greatest
head of water for flushing purposes which, under the best circum¬
stances, as I have shown, will be equivalent to a slope of about a
foot a mile, then it will be perfectly useless as a catchwater basin.
As an engineering question, therefore, Mr. Sowerby’s propositions
for the drainage of Bombay are not capable of being acted upon.
He must choose either a high level canal for flushing the sewers
very imperfectly or a low level one for surface drainage. He cannot
have one to answer both objects.
The question, therefore, is which is the more important object
—the impeiffcet flushing of the sewers or the surface drainage of the
50
Canals for
flushing the
sewers consi¬
dered.
Low level
navigation ca¬
nals consider¬
ed.
island. Tlie latter seems to me to be beyond all doubt tlie main
purpose to be fulfilled by tlie system of canals. But it does not
matter which, is adopted. The objections to canals at either a high
or a low level aro insuperable.
High level canals would cross the roads and railways in all parts
of the island at such unfavourable levels that constant obstructions
would bo caused to traffic. The expense of constructing them more¬
over would be out of all proportion to the single benefit to be deriv¬
ed by their use, viz. that of flushing the sewers. Indeed the object
of the work being so insignificant when compared with its cost,
which, as I shall show further on, will be enormous, I think I shall
be justified in assuming that the main purpose Mr. Sowerby had in
view in proposing canals was to rid the island of those enormous
volumes of water which flood it during storms and at the same time
to combine navigation with surface drainage. Supposing, tnen, that
the idea of flushing the sewers is abandoned, the canals must be ou
a low level—not higher than (as I pointed out before) 48*00 above
datum.
Now although in this position they would not be so obstruc¬
tive to traffic as high level canals which would have to cross some
of the roads nearly at a dead level, still every body must see that the
intersection of a town containing nearly a million inhabitants by
several water channels (and to he useful these should run through
the thickly populated districts) would not be conducive to the deve¬
lopment of rapid locomotion. Whenever a new road or a railway
was required the canals would invariably stand as obstacles to their
construction. Any one who has been in Venice or in a Dutch town
knows what a round-about way one has to go very often in order to
reach a place close by, and that this arises simply from the canals.
A river or a stream is an obstacle to traffic even in the country, but
the evil is increased a hundred times in a town. Place the canals
in the most favourable positions, still they will always be barriers to
traffic and to the execution of all works of public improvement.
But great as the objections even to low level canals are when
considered from an engineer's point of view, they become still greater
when viewed in a sanitary light. I am all the more surprised that
such a proposition should have come from Mr. Sowerby, because he
ought to have a sufficient acquaintance with the town of Madras to
know that nearly every sanitary improvement there is partly nullified
by the dreadful effects produced by the river Cooum. and the north-*
51
era canal. The stench from the water is at certain times of the
year overpowering. Mr. Sowerby might urge that the river and canal
are foul at present because the sewage of the town is discharged
into them. This is quite true, and, no doubt, when the sewage is
conveyed away elsewhere they will be much cleaner than at present-
But with the very best arrangements low level canals must receive
a great deal of the filth of the town. Every body knows that in
order to find the dirtiest neighbourhoods it is only necessary to go
to the lowest lying ones. Filth will accumulate there in spite of
every effort to prevent it from doing so. This is exactly what takes
place in European towns when they are intersected by canals. Any
body who has been in a Dutch town cannot have failed to notice the
very dark colour of the water in the canals. Town drainage in
Holland is in a most unsatisfactory state. The greatest portion of
the filth escapes into the canals, andhhe Dutch do not know how to
get rid of it otherwise. The water is most offensive in the warmer
months. What would be the state of things under similar conditions
in Bombay, with the addition of the heat of an Indian sun ?
With the best precautionary measures it would be impossible to
prevent people throwing rubbish and filth into the canals. Every
fall of rain, moreover, would add its quota of filth to them. In the
course of a few years the water would be not only disgusting to the
sense of sight but intolerable to that of smell.
Let us, however, consider what are the advantages which Mr.
Sowerby offers to Bombay with his canals. It is quite evident that
they are not necessary to enable us to get rid of the surface waters.
Therefore surface drainage is not a peculiarity of his scheme, or a
purpose that cannot be fulfilled by ‘other means than canals. As
far as I can understand the matter, the only advantage which be¬
longs to Mr. Sowerby^s scheme per se is that of navigation. Now
the question is whether navigation in the island is so great an
object that even engineering and sanitary objections must give way
in order to secure it. Let us consider this point.
The main canal would run from Back Bay to Makim. It must be
clear to every one that at all events at present such a canal would be
all but useless. The little traffic there now is between the south of
the island and Mahim could never justify the construction of canals,
while already there are two railways which answer not only every
purpose of the canals, but some important purposes which canals
would not fulfil at all. #
Can ala
versus
Railways.
Suppose, however, the whole of the island were to become thickly
populated, would the construction of canals be justifiable under such
circumstances ? I cannot think that they would.
What is required in a town is rapid locomotion. Now canals
would not give that. Certainly if Mr. Sowerby put steamers on the
canals it might appear at first sight that the object would be attained.
But in this case he would have to make his canals very deep, or
otherwise the filth at the bottom would be constantly stirred about by
the paddles or screws of the steamers. Now the main canal from
Back Bay to Mahim, if it were only 5 feet deep, would cost at
least 75 lakhs of Rupees; and every foot in depth over 5 feet
would cost about 5 lakhs of Rupees. So that a deep canal could
not be obtained except at a cost which would render its construc¬
tion a most expensive undertaking.
And even supposing there were to bo a deep canal with steamers
plying on it, would they offer cheaper means of locomotion than the
railway. I am certain they would not. The first cost of the canals
would render it imperative to charge high rates. Mr. Sowerby
compares the canals to the River Thames. But the Thames is a
natural water channel, and steamers pay nothing for the use of it.
Suppose the Thames had been an artificial channel, does any one
suppose that the rates charged by the steamers would be what
they now are ?
The truth is that railways are in every way better suited to the
purposes of a town than ever canals can be. The traffic between
the north and south of the island, even if it should hereafter become
considerable, would always be of that nature to demand the quickest
transport. Now steamers could never compete with railways in
this respect. And every body must see that the convenience of rail¬
ways is beyond all doubt incomparably greater than that of canals.
Supposing goods had to be sent out of the island. How could
the' canals ever compete against the railways for the traffic ? If
the goods were transported to Mahim by canal it would be necessary
to break bulk there, and to transfer them to the railways. Who
would think of incurring the cost and risk of this when he could
put them at once on the railway at Back Bay, and thus have them
conveyed without further trouble to their destination ?
I have argued the question of the advisability of constructing
canals quite seriously as a matter of duty, # But the opinions that
53
I have heard expressed in Bombay by engineers are so utterly con¬
demnatory of the scheme that I shall probably be laughed at by
some for having gone so much into the subject, especially when the
most cursory examination of the scheme should be enough to put it
out of the question altogether.
The objections which I have stated will I am sure be admitted to
be overwhelming when taken in connection with the cost of the
scheme. I have gone rather carefully into the calculations, and I
am certain that a system of canals and of sewerage, such as that
proposed by Mr. Sowerby, would not cost less ’than from 150 to
200 lakhs of rupees.
If Mr. Sowerby should think that this is an exaggeration, I beg
he will prepare an estimate and give me the opportunity to check it.
I have made the statement after much deliberation and a consider-
• •
able amount of calculation. The enormous quantity of earthwork
in the excavation of the canals, the head works where each canal
joined the sea, the land to be bought, the numerous bridges re¬
quired wherever the canals crossed the roads, the long parapets or
railings, and, in addition to all this, twelve miles of large main sew¬
ers,- many miles of branch sewers, and all the street drains; these
works would simply ruin Bombay.
Thus it will be seen that in no way are Mr. Sowerby's propositions
for the drainage of Bombay such as to demand the serious attention
of the Municipality.
1st. He has proposed canals of navigation which are to answer
both for flushing the sewers and for surface drainage purposes.
I have shown that the two objects are unattainable by any single
system of canals; that if the flushing of the sewers is to be effected
even imperfectly, surface drainage must be utterly abandoned, and
if, on the other hand, surface drainage is of paramount necessity,
then the canals will be nearly useless for flushing the sewers.
2 ndhj. I have supposed high level canals for flushing purposes to
be adopted by Mr. Sowerby, and have shown that the obstructions
to traffic caused by them would be so great, and their cost so utterly
out of all proportion to the object to be attained, that it would be
absurd to construct them.
3rclhj. I have supposed that the idea of flushing the sewers is
given up and low level canals excavated. And I have shown that
Bombay will then be reduced to the state of a Dutch town, with a
8 D
Probable
cost of tlie
scheme.
Conclusion.
54
large portion of its filth constantly accumulating in the canals. I have
pointed out that, although in a less degree than high level canals,
still to a most inconvenient extent these canals would be obstruc¬
tive to traffic and to municipal works. I have shown moreover that
for every purpose of traffic the present railways are far better
suited than any system of canals could possibly be, and lastly, that
the cost of such a scheme would simply ruin the Municipality.
It would indeed be a sad day for the inhabitants which should see
the introduction o£.canals in Bombay. While she has scarcely any¬
thing now to prevent her from being as healthy as any town in India,
and many things to make her healthier than most of them, under a
system of canals every sanitary improvement that was carried out
would in a measure be foiled in its purpose by the effects of these
huge open elongated cesspools. -
If the Municipality once admitted canals in the island, Bombay
would soon forfeit the high position she even now holds as one of
the healthiest towns in India. I do not fear that she will ever
commit so grave an error. But the consequences would be so
serious that I should be falling short of my duty if, after being asked
my opinion, I did not express it in the very plainest terms.
H. TULLOCH,
Captain Royal Engineers.
Municipal Commissioner’s Office,
3rd November 1868.
Forwarded to Government.
ARTHUR T. CRAWFORD,
Municipal Commissioner for the Town of Bombay.
BOMBAY : PRINTED AT THE EDUCATION SOCIETY’S PRESS, BYCULLA.
â– 
.V1AL A H A
SHOWING
PROPOSED SYSTEM
SEWERAGE AND DRAINAGE.
Black lines represent underground main drains for all surface waters
Red lines represent main and branch, sewers for sewage only. â– 
The figures represent levels in feet above datum lines which is 50 feet below mean sea level
To reduce the levels to Colonel DeLisle’s datum, add 29*70 to each.
Sign Water Ordinary Springs 67'25
Do. do. Neaps 55*00
Me 11 Sea Level 50*00
Lo Water Ordinary Neaps 45*00
■Do. do. Springs 42*7§
Le of floods on Plats at high water, Augu st 9th, 1868, when 14 inches of rain fell in 24 hours 54'50
FlcLevel in Native Town (Cammatteepoora) on same date 68-00
1 Wf
Mr .
The portion of ground coloured green is that proposed to be converted into a park.
SEWER STARTS WITH INVERT AT
53 00 ABOVE DATUM.
8,400
SITTIOE S
AVE 3E
SILTTICJES
&
H? 3
SECTION THROUGH A.B
SECTION THROUGH C D.
Horizontal Scale, 880 Feet to an Inch
2000 3000 -TOOO
Gooo Feet.
20