The Sun.
London, England, 1856-12-03 00:00:00

MR. BAZALGETTE'S REPORT ON THE GOVERNMENT

SOREME.
The following report of Mr. Bazalgette, the engineer
of the board, upon the points of discharge for the drain-
age of the metropolis, suggested in Capt.Burstall's letter,
and approved by the First Commissioner of her Ma-
jesty's Works, &c, was then read :

"Dec. 1.
" The point and mode of outfalls for the metropolitan
drainage which have been approved by the First Com-
missioner of her Majesty's Works, &c., marked B* upon
the accompanying map, require an extension of five fur-
longs further eastward, in Efornchurch marsh, on the
north side of the Thames, and of one mile in the Erith
marshes, on the south side.

" The outfalls would now be 15 miles below London-
bridge, and it is proposed to confine the periods of dis-
charge from them within 1i hours before high water and
24 hours after high water, with certain exceptions here-
atter named, giving a period of 8 hours' storeage and 41
hours of discharge per tide.
" The official return of the quantity cf water now sup.
plied by the water companies to the metropolis, which
has just been issued, shows that the supply has increased
from about 7,000,000 to 13,000,000 cubic feet per day
within the last 6 years, and,it is more than probable that
the quantity of sewage discharged from the sewers has
increased in the same ratio since they were last gauged
in 1853-4. Making therefore a liberal allowance for such
increase, it may now be assumed to have amounted to I
nearly 9,000,000 cubic feet per 24 hours on the north
side of the Thames, and 3,250,000 cubic feeton the south
side. Taus, the quantity which would now be. collected
in the reservoirs during the 8 hours they were closed
would amount on the north side to nearly 3,000,000
cubic feet, and on the south side to rather more than
1,000,000 cubic feet.
" The bottom of the reservoirs would be two feet
above'Ordnance datum, or at the level of the ebb tide at
2 hours after high water, that being the period when
the discharge of sewage into the river would cease.
r, 'l' The level of the overflow weir would be 161 feet
s above dcauni,, and the mean depth of the reservoirs
would be 14 feet. The reservoir on the north side would
cover about 10 acres, and contain about 6,000,000 cubic
feet when full ; that on the south would cover about 41
acres, and contain about 2,750,000 cubic feet when full;
so that the average daily flow of sewage during dry wea-
ther would about half fill the reservoirs iu eight bows.
"In order to arrive at a more accurate idea of the
time and mode of discharging the sewage from the reser-
voirs, I have obtained an abstract of the quantity of rain
which fell last year, as observed at this office. From this
it appears that there were 226 days in that year upon
which there was no rain, 90 days upon which there was
less than 1-10th of an inch, and 21 days upon which
there were rainfalls varying in depth between 1-10th and
1-sth of an inch, making 337 days upon which less than
I-sth of an inch of rain fell, and 28 days upon which
that quantity was exceeded.

" Upon tile 226 dry days the reservoirs would, as
already shown, be on the average only half full at the
end of eight hours; therefore it would be not only un-
necessary, but also impossible, to discharge any portion
of their contents into the river during the last hour of
flood-tide ; because the tide would during that period be
above the level of the sewage in the reservoir, and the
tide would thea be allowed to flow into the reservoir,
diluting its sewage, and raising its level to that of high
water in the river. The discharge of sewage would on
those 226 days commence immediately after high water,
and would be completed within 21 hours, by which time
the tide would have ebbed below the bettoni of the
reservoir. Upon the 90 days of minimum, rainfall it ap-
pears that, after making the necessary deductions for the
amount of evaporation, absorption, and the time occupied
by the rain waters m flowing from remote portions of the
district to the point of outfall, the reservoir would not be
more than about two-thirds full, and therefore the period
of discharge would on those 90 days also take place only
during the first 24 hours of ebb tide. Upon the 21 days
the reservoir would probably be nearly filled during
the 8 hours, and the discharge would then commence
1. hours before high water. Upon the remaining 28
days of heavier rain the discharge would take place at
earlier periods, varying with the amount of rain that had
fallen.

"The reservoirs, as at present designed, will there-
fore always contain a sufficient amount of reserved
space to hold the metropolitan sewage, estimated as
being due to the anticipated increase of the population
and water supply in future ages, and produced within
eight hours ; taking also into consideration the unequal
flow of that sewage during different portions of the day.
The reservoirs might, however, be added to hereafter,
from time to time, without difficulty or disadvantage, if
considered necessary ; and this mode of enlarging them
—by adding a second basin—would be preferable in an
engineering point of view to now constructing one basin
of increased area...„140 not, however, recommend any
enlargement of the reservoirs beyond the dimensions now-
named, in order to include within eight hours the rain-
fall due to the 28 days per annum, because to do this
would spread the sewage for 337 days over an unneces-
sarily large space, while on the 28 days it would be
considerably diluted, and the storm overflows into the
river would on some portion of those days necessarily
come into action at higher points in the river.
" Since September last, when I prepared a design
for carrying the lower portion of the outfall sewer on
the north side of the Thames in a direct route across
the mouth of Dagenham Gulf to point B, I have ascer-
tained that a company has been formed and an act ob-
tained last year for the conversion of this gulf into a
dock, and it is stated that preparations are now being
made to effect that object have now, therefore,
diverted the northern outfall sewer round the north side
of the gulf, instead of across the entrance. This altera-
tion has somewhat increase& the length, diminished the
fall, and necessitated a corresponding enlargement of the
sewers, which, coupled with the deepening of the reser-
voir, has increased the estimate beyond what is due to
an extension from point B to B*.
"The drainage from the high and middle level areas
on the north side of the Thames would still be discharged
by gravitation, and the lifts and pumping power already
provided on both sides of the river would remain the
same as originally designed for discharging- at point A.
"The total estimate for the metropolitan drainage as
now designed will be 2,836,6001."
In reply to Mr. Turner Mr. BAZALG ETTE stated that
the level of the Thames 21 hours after high water would
be plus 14 feet above Ordnance datum, and the bottom
of the reservoir 2 feet above the Ordnance datum ; that
he had made careful experiments at Deptford Creek with
those results ; tbat there might be a slight variation at
point 85, but that, practically, there would always be
sufficient difference of level to insure the discharge, In
reply to Mr. Doulton he said the plan was not well
adapted to extension, but that its extension could be
economically carried out by starting from Barking on
the north side, and Woolwich on the south side ; about
four miles of sewer on the north and three miles on the
south would be rendered entirely useless. And, in an-
swer to other hon. members, he said he did not appre-
hend much deposit, but would propose to remove any
that might be made by barges; he thought that no nui-
sance would arise ; that with regard to the sewer above
ground there were few canals in this country which had
not iron aqueducts, and no difficulty had ever
arisen with these. With regard to the effects of
cold the sewage was always warmer than the atmo-
spheric air, that it would flow from two to three
miles per hour, and would be from three to four
hours passing through the aqueduct; that it would not
during its progress have time to freeze, and in respect to
the flat bottoms of the reservoirs a at bottom was not
subject to an equal slow, as there would always be a
large stream. As to the capitalisation of working ex-
penses, it would be tke same as in plain B, but the struc-
tural expense would be greater by 103,0001. ; that it
would cost the same money to extend the sewers to the
sea whether plan B or plan B* was adopted, but that in
the case of plan 103,0001. more would be lost—and
that he believed that plan B was better than plan 85,
notwithstanding Capt. Borstal's report, and that cast.
iron pipes had already been tried in smaller sewers, and
had proved to be uninjured by any chemical action of
the sewage.
Mr. LESLIE said that on the ground of the expenses
of making long lines of flat-bottomed sewers, and on the
ground that reservoirs of 10 acres on the north side and
41 acres on the south side to pond back the sewage for
eight hours in every tide would be contrary to the act
of Parliament, he should move that the engineer's report
of the let of December now just read be not received.
He considered the plan to commence, Progress, and ter-
minate in error. It commenced iu error in regard to the
size of the sewers. In all previous reports the size of
sewers, pumps, &c., bad been calculated on the north
side fora discharge at 35,293 cubic feet per minute, and
on the south 16,599 cubic feet. By the plan now proposed
it was on the north 6,250 feet per minute, and on the
south 2,257 feet per minute. It progressed in error, be-
cause it divided the metropolis into two distinct parts,
north and south, whereas by the 170th section of the
act the board in assessing the sums to be charged upon
the city and other parts of the metropolis should have re-
gard to the annual value of the property, and also, in the
case of expenditure on works of drainage, to the benefit
derived from such expenditure by the several parts of i.he
metropolis affected thereby. He would call the attention
of the members for the Surrey and Kent side to what
would be the effect of the proposed plan on them. The
acreage on the Surrey and Kent side was 45,542,
while in Middlesex it was only 32,487 ; the popula-
tion on the Surrey and Kent side was 616,635 ; on the
Middlesex side 1,745,601 ; the rant on the Surrey and
Kent side was 2,257,8001., while on the Middlesex side
it was 8,894,1391. As he read the act, the whole of this
11 millions odd was to be taxed to 'ether, and not in
twe separate sums of 2 millions and 9millions. He had
no doubt the whole of the additional work would exceed
a million of money. He objected to four iron flit-bot-
tomed sewers going into the reservoir causing deposits
and becoming tide-locked. All the sewers that were

ti le-locked were nothing but cesspools, and of a most
injurious character. The sewage ought always to be it
constant motion. The hon. member, on the grounds
stated, moved that the report be rejected.
Mr. DENNIS seconded the motion. Their engineer's
report had never appeared twice in the same form. He
had always opposed the plan as being at the same time
an expensive and extravagant scheme, and one that
would never answer the purpose. He remained of opi-
nion that the sewage ought to be carried down to Sea
Reach.' No one could for a moment believe that the
Government would allow this immense nuisance to stop
at the point fixed by this plan Be. The board ought to
strike out a bold scheme, regardless of expense, and one
that would bear inspection by the whole world.
After a few words from Major LYON, the motion was
put, and, on a division, was negatived, 4 voting for it
and 23 against it.
Mr. CARPLIAEL then ruse to move that the resolution
of the board of the 22d of October last, which adopted
the engineer's plan marked B in his report, be revoked,
for the purpose of moving that the report of the engineer
in respect of the outfalls at Be, suggested in Captain
Borstal's report, and approved by Sir B. Hall, be
adopted, when an objection was taken that sufficient
notice of the motion had not been given.
The CHAIRMAN held the objection to be good, and the
motion was postponed till Tuesday next.
The board then adjourned.