Drainage—Report of the Engineer to the Commissioners

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DRAINAGE—REPORT OF THE ENGINEER TO THE COMMISSIONERS.

The pressure of other matter upon our columns during the last month has prevented us hitherto from noticing as it deserves, the Report of the Engineers to the Commissioners of Drainage of this city, upon a plan for the drainage of the First, Third and Sixth Wards.

The Engineers, in submitting their plan, make a few remarks upon the subject of drainage, generally, commenting upon the little attention which it has received in this country, so contrasted with the prominence which has been given it in the English Parliamentary Reports.

Up to 1848 the details of the sewerage arrangements of London were under the control of seven distinct boards of management, which were united in that year under one commission, called the "Metropolitan Commissioners of Sewers," embracing in their supervision one thousand miles of sewers. About this time a series of experiments were instituted for the purpose of ascertaining the proportion of decomposed animal or vegetable matter and waste from street refuse merely held in mechanical suspension. It was found to amount to 1 part in 96, taking the average velocities of the current at the ends or outfall of the sewers, and it appears that over 5,400,000 cubic feet of solid matter had been carried to the Thames yearly from a very limited number of sewers only, and by the force of the water alone, although all their sewers are built upon the principle that they should be large enough for workmen to enter and remove the matter by hand. In one division alone, embracing 48 miles of sewers, over 2000 loads had to be annually removed in this manner.¹

In the report received from the Engineer of this Commission,² the principles of Town Drainage were laid down as follows:

That two outfalls, should be provided: one for the discharge of land and surface waters, and the other for the discharge of house and soil drainage. That in order to perfectly drain the subsoil, a system of permeable land drains and sewers should be provided, to discharge into the natural water courses and rivers. That as outfalls are already provided by streams and rivers for the discharge of the natural waters, it is only necessary to provide separate and proper outfalls for this discharge of the artificial or house and subsoil drainage, which outfalls should convey the sewerage as fast as it is produced, to a depot at a convenient and unobjectionable place. That, in order to carry off the house and soil drainage, without contaminating the atmosphere of the town by the escape of effluvia through the numerous inlets, a system of impermeable drains should be provided, to discharge without intermission into the said artificial outfalls, independently of the rivers. That at the main outlet a depot should be formed, and works established, for raising the sewerage, and connecting and distributing the same for agricultural and horticultural purposes.

Discarding some of the above provisions as unnecessary, here, the Brooklyn Commissioner’s come to the following essentials necessary to an effectual drainage:

First, A system of impermeable drains through which the waste matter both of the surface and from the dwelling, assisted by the supply, are removed to their outlets at tidewater, forming a combined system of water supply and drainage; and second, such a fall and dimensions should be given to the drains and sewer, as shall insure if possible, their self-cleaning action without having recourse to removing the contents of the sewers by hand. That this may be accomplished in Brooklyn in view of the quantity of water at command, as also the inclination attainable for the main sewers, (at all events in that part of the city now under consideration,) there can be no question.

The plan accompanying the Report shows that the Engineers have aimed at bringing all the drainage possible into the Bay, between the extreme points of Hamilton avenue and Fulton ferries.—Owing to the conformation of the shore, all refuse thrown into tide water between these points may be expected to be carried off without further trouble. The whole area drained amounts to 562 acres, covering twenty miles of streets, and requiring sixteen outlets into the Bay. Nine of these are short and drain but a single block and their outlets need not be carried below low water. The remaining seven outfalls stand. Of these seven, five are already built, viz;—Fulton street sewer, Pierrepont street sewer, private sewer between Montague and Joralemon streets, Warren street sewer, Hamilton avenue sewer.

The dimensions of those brick sewers already built are quite ample for the service, Fulton sewer being 6 feet in diameter for a length of 700 feet, and 5 feet in diameter for about 740 feet, and the remainder of its length, 1,600 feet, being eliptical, 4 feet by 5 feet. It terminates at the summit of Fulton street, opposite the Globe Hotel, and is provided with street basins and gully shoots at the corners of all the streets. It discharges two-and-a-half feet below high water.

The sewers are to be of the best hard brick, well laid in cement, and true and uniform in section—the grade of street sewers to be generally thirteen feet below the level of the curb. It can hardly be doubted that with such precautions as it will be in the power of the Commissioners to adopt there need be no apprehensions that the more economical system of drainage proposed, will not effect all the desired improvements in the health and comfort of that portion of the city where it may be introduced.

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