London Labour and the London Poor, Vol. 2

by Henry Mayhew

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 ¼ 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 (1,080,000l.). 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.