The Sun.
London, England, 1857-11-06 00:00:00

METROPOLITAN BOARD OF WORKS.

CONFERENCE WITH SIR BENJAMIN HALL
ON ME MAIN DRAINAGE OF THE
METROPOLIS,
The Metropolitan Board of Works originally

submitted a plan called plan B to the First Com-
missioner of her Majesty's Works and Buildings
for the main drainage of the metropolis. This
plan was rejected, on the ground that it did not
fulfil the requirements of the Act of Parliament.
A second plan, called plan Blt, was then prepared,
and laid before the Commissioner, by whom it was
referred to Capt. D. Galton, R.E. Mr. Jas. Simp-
son, C.E., and Mr. T. E. Blackwell, C.E., for con-
sideration. These gentlemen made their report on
the 31st of July last, in which they recommended a
system of drainage varying in many material re-
spects from that proposed by the Metropolitan
Board of Works, and involving numerous modifi-
cations of that plan. The Metropolitan Board
came to a resolution rejecting the plan of the Go-
vernment engineers, and on Friday last addressed
a letter to Sir B. Hall, in which they assigned
their reasons for so doing, and at the same time
requested an interview with him on the subject.
A conference was accordingly held yesterday at the
office of the Board of Works, Whitehall-place, be-
tween Sir B. Hall, the First Commissioner (who was
assisted by Capt. D. Galion and Mr. Simpson), and
Mr. Thwaites, the chairman of the Metropolitan i
Board, accompanied by Mr. Woolrych, the clerk,
and Mr. Bazalgette, the engineer of the board.
Mr. THWAITES —This, Sir Benjamin, will be the
third time I have had the honour of appearing be-
fore you on the all-important subject of the main
drainage of the metropolis. It is now within a few
days of a twelvemonth ago that I presented to you
plan 85. That plan has been referred by you to
three gentlemen of the highest eminence and re-
spectability. The delay that has arisen out of that
reference is a matter which the Metropolitan Board
of Works deeply regret. lam not about to blame
you for having so referred that plan ; probably it
was the course which any person under similar cir-
cumstances would have adopted. Neither am I pre-
pared to blame the referees for the time taken by
them for the consideration of this important sub-
ject. Indeed, they have acknowledged in their
report that so vast has been the question that the
time occupied by them (being somewhat about nine
months) has been insufficient to enable them care-
fully to master all the details and difficulties of the
matter. No doubt, the referees found that the more
they investigated the subject the more it was beset
with difficulties which did not appear on the sur-
face.
Without making any further prefatory remarks
I beg to express a hope that the result of the present
conference will be to rescue the question from all
engineering conflicts on the one hand, and from
fierce personal and private jealousies on the other.
I trust that we shall be able to bring to bear on the
subject such an amount of common sense and prac-
tical knowledge as shall result in relieving the in-
habitants of London of those evils arising from an
imperfect and an impure state of drainage from which
they have been sufferinefor so many years. The hon.
gentleman then proceeded- to call the attenion of
Sir B. Hall to the reasons which had induced the
Metropolitan Board to refuse the adoption of the
plan proposed by the Government engineers. One
very serious objection was the proposed increased
area which the plan of these gentlemen compre-
hended. Upon that subject, probably, it was only
necessary for him to refer to the fact that upon Sir
Benjamin'sown motion Parliament had but recently
fixed the extent or area to be dealt with bythe Board
of Works, and there might probablyat this period be
some difficulty in extending that area. But there
were other objections to an extension of the area, to
which he begged to call especial attention. The area
under the jurisdiction of the Metropolitan Board
comprised 117 e square miles. The area which the
Government referees proposed that the Board should
have to deal would comprise 354 square miles ; the
drainage of a large portion of the additional districts
being simply that of the rainfalls, the ordinary ma-
nure of those districts being applied to agricultural
purposes. But what would be the consequence to
the ratepayers of thus increasing the area ? It
would be necessary to increase the size of the sewers
some three or four times in capacity ; while fur the
greater portion of the year, owing to that increased
size, the sewage would be running in mere driblets,
the result of which would be a vast deposit, and an
inefficiency in the general action of the sewer alt '-
Ober opposed to those hydraulic principles which
guided engineers in the construction of such works.
The deposit in the sewers of London was a very im-
portant question. It involved an annual expense of
26,0001. to remove the deposit which remained stag-
nant in the present sewers. The object both of Par-
liament and of the Board must be so to coustructthe
sewers as to insure a sufficient scouring power to re-
lieve the districts that were suffering from these de-
posits. If the extended area were adopted the tunnels
would be so enlarged as greatly to increase the diffi-
culties which the Board would have to contend with
in other respects. The sewers to be constructed
would be of such an enormous size as to be almost
impracticable in the streets of London. Another
point adverted to by the Government engineers
had engaged his attention. They stated that one
cubic foot of sewage mixed with five times its bulk
would become innoxious. They, indeed, laid this
down as a principle—be might almost call it their
formula, by which they regulated all their proceed-
ings, for he found that their main deductions were
founded on that proportion. It was impossible, as
no doubt the referees had themselves ascertained,
to carry off the whole of the rain water during the
entire year, and the plan of the Board made that
admission; but with the view of preventing an over-
flow of water into the Thames for some ten days in
the yearthesegeetlemen proosed additional sewers,
or rather sewers of an add tonal size, involving a
frightful expense of money. And why should all
this be It What would be the proportion of the
sewage to the rain water when the channels were
surcharged and the contents passed over into the
Thames ? Taking every various condition of the
sewage, he found that that which would pass over
the tunnel into the Thames would be in the propor-
tion of 7i cubic feet of water to one of sewage. This
was a larger dilution than that which the referees
stated would be necessary in their own opinion to
be obtained ; therefore one would logically arrive at
the conclusion that to increase the size of these
sewers for the purpose of preventing during a few
days in the year this diluted sewage from flowing
into the Thames was altogether unnecessary. The
referees did not themselves propose the introduc-
tion of a large stream of water which would effectu-
ally carry off all the sewage throughout the whole
year. They admitted that during certain days in
the year some portion of the sewage must pass over
into the Thames, and yet to effect so small an ob-
ject they proposed a plan that would involve a moat
disproportionate expenditure. He would now call
Sir B. Hall's attention to the proposition for the
construction of open sewers. The Metropolitan Lo-'
cal Management Act expressly provided that the
Board should not oonstruct any works so as to be-
come a nuisance. It had hitherto been the policy of
the Board and of all preceding commissions to abo-
lish all open sewers; but the referees appeared to
be of opinion that by a mixture of five parts
water and one part sewage the evil effects
generated by the impure gases arising from open
sewers would be destroyed, or, in other words that
a constant flow would prevent those consequences
which would arise from tt Mere stagnant pool. The
time that would be occupied iu discharging the
sewage at the outfall, and the time required by de-
composition of the sewage by the action of the at-
mosphere, were questions he would not enter upon.
then, but he apprehended that Sir B. Hall 000!
not fail to arrive at the same conclusion the Boars,
itself had arrived at, that open sewers were entirely
inadmissible, and that it was a proposition which
could never be sanctioned. After some technical
criticisms as to the practicability of cmstructing
those elongated open sewers, and as to the admis-
sion of water into them fa. the purpose of carrying
off the sewage, he stated that the Board were ap-
prehensive that to effect the object proposed by
the referees the navigation of the river itself would
be greatly prejudiced, and that in order to have
a quantity of water equal to the ordinary flow
of the channels it would require the construc-
tion of reservoirs that would occupy no less than
460 acres of land, an area equal to that of Hyde-park
and Kensington-Gardens together. He need not
say that any scheme requiring such a work in order
to keep up the proposed discharging power was al-
together inadmissible. The mechanical power that
would be required to lift thowater from the Thames
into these channels would be attended with an an-

Intel cost of 36,0001.—a most onerous burden on
the ratepayers of London, and one which demanded
the most serious consideration of the First Com-
missioner before giving his sanction to any such
plan. The next point to which he begged to call
attention was the proposed extension of the out-
fall. That had been already the subject of confe-
rence. On the 20th of Nov. last year, a deputation
presented to Sir B. Hall the plan B with a star,
and it was accompanied with a resolution passed by
the board, declaring their readiness to carry out an
extension of their own plan if the Government
wished it to be done ,and were willing to assist in
providing funds for that purpose. On that occasion
a member of the deputation asked whether they
were to understand that the plan indicated in
Capt. Burstall's letter as to the points of outfall
was satisfactory to the First Commissioner, when
Sir Benjamin Hall said he did not think he should
be justified in going beyond those points, because
if he did ho should be asking them to expend
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