In laying out a plan of drainage and sewerage when a river or brook passes through or alongside of a town, it will naturally become the main drain of the place, and be the normal line from whence the second-class sewers would diverge; but it not unfrequently happens when such a brook is small and becomes the cloaca maxima, that, being left open, and insufficiently supplied with water in the summer season, it constitutes, instead of a benefit, a serious nuisance to the inhabitants; instances of this kind may be observed at Edinburgh, Birmingham, Coventry, Camberwell, &c., &c. It also happens at many towns that a stream passing through or by them is dammed up to turn a mill just above or below the town, or even in the middle of it, by which means the current useful to clear away the filth is diverted, the water in the bed of the stream into which sewers are discharged is left stagnant, while the vicinity of the town is rendered wet and unwholesome from the pent up water.
At Birmingham the Rea Brook is dammed up in its course through the town to supply a mill. In the very excellent sanitary report of the town by Dr. Hodgson and other medical gentlemen, it is stated that “the river Rea may be considered the cloaca or main sewer of the town, but that its condition is very bad;” the report also states, “that the stream is sluggish, and the quantity of water which it supplies is not sufficient to dilute and wash away the refuse which it receives in passing through the town, and that in hot weather it is consequently very offensive; and in some situations in these seasons is covered with a thick scum of decomposing matters; and this filthy condition of the river near the railway stations is a subject of constant and merited animadversions, and that it requires especial attention lest it should become a source of disease, &c.”
The cloaca maxima of Birmingham differs from that of ancient Rome; that whereas in the latter art was employed to effect what nature had left undone, here art has been employed to obstruct the useful course of nature. I quite agree with the sanitary report as to the present noxious state of the brook; and even those who travel on the railway may at times be very sensible of the effluvia when crossing it.
I am inclined to differ from the sanitary report as to insufficiency of the water of the Rea for cleansing its own bed; but that report has not adverted to the fact of the abstraction and diversion of the water of the Rea from its natural bed to turn a mill, a fact which will amply account for the deficiency and sluggishness of the current in the very places where the contrary condition is most wanted.
From my inspection of the locality, I am inclined to believe that the descent of the Rea and its quantity of water in passing through the town of Birmingham is sufficient under good arrangements for the efficient and wholesome sewerage of its bed.
If we take a distance of half a mile above the weir and half a mile below it, that is, nearly from Morley-street to Lawley-street, I consider I shall be justified in saying there is a descent of about 14 feet, for I find a slight weir in Floodgate-street; at the dam itself the fall is about eight feet, and from thence for a considerable distance downwards the fall is considerable.
Above the weir the stream for a short distance is sluggish from want of declivity, and the water being pent up, keeps the houses there wet or damp, while below the weir the bed of the Rea being left nearly dry, the filth from the sewers which discharge there must stagnate, while at the same time the water of the Rea passing through the mill-race with a good body and current, applies to no act of cleansing.
The mill-pool is extensive but shallow, and there the filth from above accumulates. When the pool is filled with water it is worked off by the mill, but the gratings prevent dead dogs and such like matter from passing, and are there left to fester at low water.
The remedy is as easy as the evil is great; all obstruction being removed from the course of the brook and the water restored to its original bed, the object would be effected; as to the value of the mill-power which would thus be subverted, it cannot be a matter of much amount in a place where coals and steam-engines are so cheap, and where the constant and regular work of the mill must be an object of some importance.
In applying a remedy to the great evil under notice, the engineer should not be content by merely restoring matters to their original and natural state, but in so populous a town should apply all the aid which art can bestow to assist natural circumstances. The bed of the Rea should be formed with an uniform descent through the town and for some distance below it, by dredging in some places and filling it in others with coarse gravel or broken stones; or, better still, if funds will afford it, by forming an inverted arch of stone or blue bricks to give full effect to the scour of the stream; further, the engineer would render the course of the brook through the town as straight as circumstances would permit by cutting off loops and sinuosities. In this manner, and by reserving the whole body of the water of the Rea for cleansing its own bed, I have no doubt that this main sewer of Birmingham would become as conspicuous for its wholesome and efficient action as it is now for the contrary.