On the eastern bank of the Lea the sewage of both districts is to
be concentrated. The high-level sewer will commence and _cross_ the
Lea near the “Four Mills.” It is then to proceed “in a westerly
direction under the East and West India Dock Railway and the Blackwall
Extension Railway, beneath the Regent’s-canal, to the east end of the
Bethnal-green-road, at the crossing of the Cambridge-heath-road, at
which point it will be joined by the proposed northern division of the
Hackney-brook, which drains an extensive district up to the watershed
line north of London, including Hackney, Stoke Newington and Holloway,
and part of Highgate and Hampstead; from thence the main sewer proceeds
along the Bethnal-green-road, Church-street, Old-street, Wilderness-row
(where a short branch from Coppice-row will join) to Brook-street-hill;
from thence to Little Saffron-hill, where a distance of about 100 yards
is proposed to be carried by an aqueduct over the Fleet-valley; thence
along Liquorpond-street, at the end of which it will receive a branch
from Piccadilly, on the south side, and a diversion of the Fleet-river,
on the north side; thence along Theobald’s-road, Bloomsbury-square,
Hart-street, New Oxford-street, to Rathbone-place (where it will
receive a diversion of the Regent-street sewer from Park-crescent),
along Oxford-street, and extending thence across Regent-circus to
South Molton-lane (where it will intercept the King’s Scholars’ Pond
sewer), continuing still along Oxford-street to Bayswater-place, Grand
Junction-road, Uxbridge-road, where it is joined by the Ranelagh sewer,
the sewage of which it is capable of receiving, and at this point it
terminates.”
It is difficult to convey to a reader, especially to a reader who
may not be familiar with the localities of London generally, any
adequate notion of the largeness, speaking merely of extent, of this
undertaking. Even a map conveys no sufficient idea of it.
Perhaps I may best be able to suggest to a reader’s mind a knowledge
of this largeness, when I state that in the district I have just
described, which is but _one_ portion (although the greatest) of the
sewerage of but _one_ side of the Thames, more than half a million of
persons, and nearly 100,000 houses are, so to speak, to be sewered.
The low-level tract sewerage, also, concentrates on the Lea, “near to
Four Mill’s distillery, taking the north-western bank of the Limehouse
Cut, at which point it receives the branch intended to intercept
the sewage of the Isle of Dogs; thence continuing along the bank of
Limehouse Cut, through a portion of the Commercial-road, Brook-street,
and beneath the Sun Tavern Fields, into High-street, or Upper
Shadwell; thence along Ratcliffe-highway and Upper East Smithfield,
across Tower-hill, through Little and Great Tower-streets, Eastcheap,
Cannon-street, Little and Great St. Thomas Apostle, Trinity-lane, Old
Fish-street, and Little Knight Rider-street; thence beneath houses in
Wardrobe-terrace, and on the eastern side of St. Andrew’s-hill, along
Earl-street to Blackfriars-road. From Blackfriars Bridge it is proposed
to construct the sewer along the river shore to the junction of the
Victoria-street sewer at Percy-wharf; which sewer between Percy-wharf
and Shaftesbury-terrace, Pimlico, becomes thus an integral portion of
the intercepting line; at Bridge-street, Westminster, a branch from
the Victoria-street sewer is intended to proceed along Abingdon and
Millbank-streets, as far as and for the purpose of taking up the King’s
Scholars’ Pond and other sewers at their outlets into the Thames.
From Shaftesbury-terrace the Victoria-street sewer is proposed to be
extended through Eaton-square and along the King’s-road, Chelsea, to
Park-walk, intercepting all the sewers along its line, and terminating
at a point where the drainage of Kensington may be brought into it
without pumping.”
The lines of sewerage thus described are, then, all to the _west_ of
the Lea, and all, whether from the shore of the Thames, or the northern
reaches in Highgate and Hampstead, converging to a pumping station
or sewage-concentration, on the _east_ bank of the Lea, in West Ham.
By this new plan, then, the high-level sewer is to _cross_ the Lea,
but that arrangement is impossible as respects the second district
described, which is _below_ the level of the Lea, so that its course
is to be _beneath_ that river, a little below where it is crossed by
the high-level line. To dispose of the sewage, therefore, conveyed from
the low-level tract, there will be a sewer of a “depth of _forty-seven_
feet _below_” the invert of the high-level sewer. This sewer, then, at
the depth of 47 feet, will run to the point of concentration containing
the low-level sewage.
At this point of the works, in order that the sewage may be collected,
so as to be disposed of ultimately in one mass, it has to be _lifted_
from the low to the high-level sewer. The invert of the high-level
sewer will at the lifting or pumping station be 20 feet _above_ the
ordnance datum, while that of the low-level sewer will be 27 feet
_below_ the same standard. Thus a great body of metropolitan sewage,
comprising among other districts the refuse of the whole City of
London, must be lifted no less than 47 feet, in order to be got rid of
along with what has been carried to the same focus by its natural flow.
The lifting is to be effected by means of steam, and the pumping power
required has been computed at 1100-horse power. To supply this great
mechanical and scientific force, there are to be provided two engines,
each of 550-horse power, with a third engine of equal capacity, to be
available in case of accident, or while either of the other engines
might require repairs of some duration.
The northern sewage of London (or that of the Middlesex bank of the
Thames, covered by that division of the capital) having been thus
brought to a sort of central reservoir, or meeting point, will be
conveyed in two parallel lines of sewerage to the bank of the river
Roding, being the eastern extremity of Gallion’s Reach (which is below
Woolwich Reach), in the Thames. The Roding flows into the Thames at
Barking Creek mouth. The length of this line will be four miles.
“At this point,” it is stated in the Report, “the level of the inverts
of the parallel sewers will be eight feet below high-water mark, and
here it is intended to collect the sewage into a reservoir during
the flood-tide, and discharge the same with the ebb-tide immediately
after high-water; and, as it is estimated that the reservoir will be
completely emptied during the first three hours of the ebb, it may be
safely anticipated that no portion of the sewage will be returned, with
the flood-tide, to within the bounds of the metropolis.”
The whole of the sewage and rainfall, then, will be thus diverted to
_one_ destination, instead of being issued into the river through a
multiplicity of outlets in every part of the northern shore where the
population is dense, and will be carried into the Thames at Barking
Creek, unless, as I have intimated, a market be found for the sewage;
when it may be disposed of as is most advantageous. The only exceptions
to this carrying off will be upon the occurrence of long-continued and
heavy rains or violent storms, when the surplus water will be carried
off by some of the present outlets into the river; but even on such
occasions, the _first scour_ or cleansings of the sewerage will be
conveyed to the main outlet at the river Roding.
The inclination which has been assigned to the whole of the lines
of sewers I have described, is, with some unimportant exceptions, 4
feet per mile, or 1 in 1320. These new sewers are, or rather will be,
calculated to carry off a fall of rain, equal to 1/4 inch in 24 hours,
in addition to the average daily flow of sewage.
Mr. Forster concludes his Report:--“I am only able to submit
approximately that I estimate the cost of the whole of the lines
of sewers, the pumping engines, and station, the reservoir, tidal
gates, and other apparatus, at one million and eighty thousand pounds
(1,080,000_l._). This estimate does not include the sums required for
the purchase of land and houses, which may be needed for the site of
the pumping engine-house, or compensation for certain portions of the
lines of sewers.”
As regards the improvements in the sewerage on the south side of the
Thames (the great fever district of the metropolis, and consequently
the most important of all, and where the drainage is of the worst
kind), I can be very brief, as nothing has been positively determined.
A somewhat similar system will be adopted on the south side of the
Thames, where it is proposed to form one main intercepting sewer; but,
owing to the physical configuration of this part of the town, none
of the water will flow away entirely by gravitation. There will be a
pumping station on the banks of the Ravensbourne, to raise the water
about 25 feet; and a second pumping station to raise the water from
the continued sewer in the reservoir, in Woolwich Marsh, which is to
receive it during the intervals of the tides. The waters are to be
discharged into the river at the last-named point. The main sewer on
the south side will be of nearly equally colossal proportions; for its
total length is proposed to be about 13 miles 3 furlongs, including the
main trunk drain of about 2 miles long, and the respective branches.
The area to be relieved is about proportionate to the length of the
drain; but the steam power employed will be proportionally greater upon
the southern than upon the northern side.
There are divers opinions, of course, as to the practicability and
ultimate good working of this plan; speculations into which it is
not necessary for me to enter. Mr. Forster has, moreover, resigned
his office, adding another to the many changes among the engineers,
surveyors, and other employés under the Metropolitan Commission; a fact
little creditable to the management of the Commissioners, who, with one
exception, may be looked upon as irresponsible.