near Birmingham. Preliminary to carrying the Gloucester Railway through
the village, in deep cutting, it had been ascertained by trial shafts
that the bottom consisted of quicksand, which rendered it difficult
either to construct a tunnel or to support the slopes in open cutting
until the water was removed; and for this object a drift or level was
brought up from a distance of a quarter of a mile through a bed of marl;
the miners proceeded for some distance perfectly dry until they reached
the quicksand, when the water flowed into the drift at the rate of 253
cubic feet per hour, or 77½ gallons per minute, and the wells in the
village in a short time were laid dry, and had to be deepened at the
expense of the Railway company. It so happened in this instance that the
level of the quicksand was so deep that the surface of the land had not
been affected by the pending up of the water below; but if it had been
otherwise, the measure resorted to would have proved as useful to the
land as it was to the Railway.
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.
About a mile above the town of Birmingham, there is another mill which I
am disposed to think would act rather beneficially than otherwise, in
removing the filth from the bed of the brook in its course through the
town; for in summer weather when the stream is scanty, by pooling it up
and letting the water down with force at intervals, the effect is much
increased. Whether the stream of the Rea be so deficient in summer as to
require this process, I would not now give a positive opinion, but there
are many somewhat analogous cases where the stream in summer is not
sufficient and where the pooling up and flushing off at intervals could
not but prove of great utility; and if I have now brought the case of
Birmingham into considerable detail, it is owing to the circumstance of
its exemplifying certain conditions that are common to a great number of
towns, and which, in a sanitary point of view, and more especially in
regard to the poorer classes of the community, are the most urgent for
remedy of any that have fallen under my observation.
In the town of Haddington, a mill-dam crosses the river Tyne in its
passage through the place and into the mill-pool; the main sewer is
discharged with a diminished and sluggish descent; and on occasion of
floods in the river, the water passes up the sewers and occasionally
lays the lowest part of the town under water. It would not be difficult
to direct the main sewer into the bed of the river below the dam or
weir, and by the additional declivity give some current to the water of
the sewer, which from the pending up of the river at its present outlet
has rendered it almost stagnant, so much so, that in hot weather, and
where it is not covered over, the exhalations are very offensive; but
was the sewer improved by the alteration mentioned, still the pooling up
of the river for the mill keeps the lower part of the town damp, and
even subjects it to partial inundations.
One of the medical officers reports, that when “fever has been at any
time prevalent in the town, it has been most so in a portion of it
called the Nungate,[50] lying close by the river, when during the summer
and autumn it is occasionally almost stagnant, and where there is a
considerable decomposition of vegetable matter.”
Another medical gentleman, speaking of the main sewer, says, “this small
burn is a receptacle of the privies and refuse of vegetable matters from
the houses near which it passes; and in those parts where it is
uncovered, it forms an excellent index of the weather; previous to rain
the smell is intolerable.”
The same gentleman proposes as a remedy that another small burn, having
a parallel course at a short distance, should be turned into the sewer
to aid the sewerage. From my knowledge of the locality, the
recommendation, I should say, is judicious, but in this manner, though
the supply of water would be increased, the declivity or rather want of
declivity of the sewer would remain the same, and could only be improved
by removing the mill-dam, or directing the sewer into the bed of the
river below it, as already mentioned. Unquestionably from the pending up
of the river, the lower part of the town is at present very ill drained,
and it is somewhat remarkable that it was the first site in Scotland
visited by the Asiatic cholera.
In reference to the two cases cited and to others of a similar nature,
it should be remarked, that the vicinities of the nuisances are chiefly
inhabited by the poorer classes, and who from want of influence in their
own parts are the more necessarily thrown under the protection of state
regulations.
The sewers of a city or town may be conveniently divided into four
classes:—First, the main drain or sewer, and this, whether natural or
artificial, being fixed, becomes the basis of the system, and upon it
the second drains or district class will be directed: these again will
receive the third class or street drains; and lastly, the house or
fourth class drains, will be discharged into the street drains. In small
towns, only the third and fourth class drains will be required; in large
towns, three classes of drains may be necessary; and in great cities,
all the four classes will be required.
PLAN OF SEWERAGE
[Illustration]
[Illustration:
STREET SEWERS (_o._ _p._)
]
[Illustration:
DISTRICT SEWERS (_c._ _d._)
]
[Illustration:
MAIN SEWERS (A. B.)
]
[Illustration:
_Fig. 1._
]
[Illustration:
_Fig. 2._
]
With respect to the form of the drains, when bricks are used as building
materials, the bottoms of the drains will be best formed of inverted
arches of blue bricks, as forming a cheap, hard, and durable surface,
and giving every facility from the form, for the scouring force of the
water to remove the filth brought into the drain; but whether the curve
of the bottom shall be a semicircle or a segment will, I apprehend,
depend on the size of the drain. For very small drains a circular form
would be the cheapest and best; the next size would be more
advantageously constructed of an oval or egg shape, but still of bricks.
Drains of a still larger size, viz. the second class, may be
conveniently made either of brick or stone, arched and counter-arched at
top and bottom with battered sides, either straight or curved; the
counter-arches or curved bottoms will conveniently become flatter as the
drains increase in capacity to afford greater room for the accumulated
water to pass without rising and flooding back into the feeders. The
first and second-class sewers must be deep seated to receive their
respective tributaries or feeders, with some overfall; and though a
sufficient width for large drains may generally be procured, it is
difficult in many cases to command enough of depth, another circumstance
that can best be obviated by flattening the arches both at top and
bottom; but in large drains, where there is a body of water, the
scourage will be sufficient, without resorting to deeply curved bottoms.
When bricks abound as a building material, they are particularly
convenient for the construction of deep sewers and drains, from the
facility of handling in confined spaces; but it is important their
quality should be of the best, since if they scale and decay, great
expense must be involved in the repair of the drain. The Tipton, or blue
brick, is the best for the facework of drains.
In parts of the country where stone abounds, bricks are often little
known, and the resources of the district must be made use of; where the
blue lias limestone occurs, I have found it a cheap and excellent
material for forming culverts and drains of all sizes; and it was used
largely for that purpose on the Birmingham and Gloucester Railway.
Annexed is a sketch of the sections of drains varying in form according
to their size. The batter which I found most useful and convenient for
wall-sided drains was 1 in 9, either curved or straight; the first is
the best form in theory, but in small works I found the bricklayers’ and
masons’ work more accurately to the straight batter; and the last is,
from its simplicity, better adapted to receive any sluices or
flush-gates that may be necessary.
Annexed is also a sketch to show the distribution of drains in a town
supposed to be built on a regular plan, with a pretty uniform descent
towards an axis, which constitutes the site of the main drain; each
class of drains consisting of several sizes, it would be most useful as
well as economical that the drain of a particular class (if large)
should commence with the smaller size, and discharge or terminate with
the greater size, a plan that would aid the sewerage of the water.
In a system of drainage, it is necessary to consider that the greater
the body of water, or in other words, the class of the drain, the less
declivity is sufficient; and the converse, the less the body of water,
or class of drain, the greater declivity is required; in the first case,
the hydraulic depth compensates for the want of declivity; and in the
second case, the declivity compensates for the want of hydraulic depth;
the multiplication of these qualities being a function of the velocity
or force of the current, due attention to the above is important in
economizing or turning to the best account the declivity for the
drainage of a large town.
Having arranged the system of sewerage for a town, the next object will
be to render it as extensively useful as practice will admit of; and
from the experiments and practice of Mr. Roe, the surveyor to the
Holborn and Finsbury Commission of Sewers, we are warranted in the
belief that a good system of sewerage, aided by a sufficient supply of
water, will, in most localities, be sufficient to remove all the dirt
which arises in the streets, without the necessity of cartage, and also
all the filth of private dwellings which is at present led through
drains or pipes, or which by the aid of water may be practised more
extensively in future.
We have first to consider the conveyance or discharge of the street dirt
into the main sewers, and the discontinuance of the present expense, and
annoyance of using carts for that purpose, at least with some few
exceptions.
It is pretty obvious, that if the mud of London, like water, could be
made to flow through the drains much trouble and expense of cartage
would be saved; and it does happen that the street-dirt of London is so
diffusible with water, that with a little arrangement such a mode of
cleansing maybe followed; indeed it is highly probable that at present
more than one-half of the whole mud is carried off by the rains in that
manner.
The mud of London, and other great towns in England, may be assumed in
wet weather[51] to arise, in three-fourths of its amount, from the
grinding or abrasion of the paving-stones, the remaining one-fourth part
consisting of soot, shop-sweepings, and cattle dung.
The dirt arising from the detritus of the stones may be obviated in two
ways; 1st, by substituting for the green-stone forming the carriage-way,
quartz-rock, or quartzose stones. The green-stones contain hornblende
and felspar, which grind, like all argillaceous stones, into fine mud or
powder mixable in water, whereas quartz rock retains when ground the
form of clean sand, neither soiling nor capable of forming mud in
itself. The Lickey Hills in Worcestershire are composed of quartz rock,
and the roads in their vicinity show its excellence as a material for
road making. The quartz rock, however, of the island of Jura is much
purer, and that island contains an inexhaustible supply already broken
by nature into sizes nearly fit for laying on the roads; and Small’s Bay
in the island of Jura would form a convenient loading place, and by
means of a jetty and tram-way vessels might be laden at a small expense,
and much of the country supplied with the best of all materials for
road-making. The substance of the stone is hard and durable, and
consequently suffering little by abrasion; and it would be well worth
while to try the experiment of Macadamizing one of the leading streets
of London with this material, as the means of forming a good road, and
at the same avoiding the creating of a great quantity of street dirt.
The other mode of avoiding the formation of mud is the substitution of
wooden pavements; of the success of these I have little doubt, though
for the present many failures have occurred, either from The foundation
not having been truly and firmly laid, or from the blocks of wood not
being massive enough. The greatest objection to wood pavements at
present is the slipping of the horses, but this I believe might be
obviated.
The question, however, at present is to get rid of the street dirt, such
as it is; and for that purpose I apprehend it would only be necessary in
wet weather during rains that the street-cleaner should sweep the dirt
into the kennels, and aid the water by stirring the mud, to carry off
the material in a state of diffusion; in dry weather, the opening of
pipes with hose attached would serve the same purpose as the rains, and
at the same time aid the sewerage at the time most required. After a
short but heavy fall of rain, the cleansing effect of the water is fully
perceived: and if any means could be devised of saving the rain-water
that falls on the houses and in the streets, so as to apply it in
considerable quantities at intervals, it is probable that the rain-water
would be amply sufficient for all the purposes in question.
I have heard of the plan pursued by the West Middlesex Water Company for
cleansing their reservoir at Kensington, at little expense, by diffusing
the muddy deposit in water, and allowing it to run off in pipes.
In the city of Guanaxuato in Mexico, a similar mode of cleansing has
been long practised; a splendid tank of ample dimensions contains the
water used by the inhabitants; the tank is supplied by mountain
torrents, which bring down a considerable quantity of mud or silt, and
which makes a deposit in the bottom of the tank, which is formed by a
fine dam of masonry crossing a narrow valley, and provided with sluices.
The rainy season commences in the latter part of June, and a short time
previous the ceremony of emptying and cleansing the tank is gone
through; a kind of fair and holiday is held on the ground, to which most
of the inhabitants resort; the sluices are opened, and as the water
recedes, the watermen, boys, and all those who relish the fun, get into
the tank and keep stirring up the silt with sticks and spades, &c., and
in this manner the mud is annually carried off by the remaining water of
the past season, a subsidiary tank serving for use until the principal
one is replenished.
By some sort of a similar process it is alleged that much of the
mud-banks of the Thames above the bridges have been removed, viz., by
the action of the paddle-wheels of the numerous steam-boats running
there. Some of the effect observed must be owing to the greater scour of
the tides since the removal of Old London-bridge, though some part may
also be due to the steam-boats.
For the purpose of giving more aid to the surface-water in cleansing the
streets, and at the same time for keeping the footways and houses drier
and more free from mud, I should propose (at least as an experiment) a
different structure of the carriage-way, viz., to make it incline to a
centre kennel, instead of to two side ones. At present, in many places,
the centre of the carriage-way is elevated above the level of the shop
doors, and at the same time we often find the footway but three inches
higher than the kennel; and it is pretty obvious from this arrangement,
in dry weather, the dust will blow from the more elevated carriage-way
on to the footways, and into the shops and areas; and in wet weather the
water and mud being chiefly accumulated in the side gutters, the
carriage wheels and horses’ feet will distribute it plentifully on the
footways, and not unfrequently on the passengers, and all tending to
keep the houses damp and dirty, whereas it is obvious that, was the
descent constant from the houses[52] on either side to the centre of the
street, these evils would be avoided, and it will be no less evident
that all the surface-water flowing to one common channel would possess
more force and convenience for running the street dirt into the sewers.
I am inclined to believe that the carriage-ways are getting gradually
elevated above their proper level, from the contractors for paving not
excavating deep enough for the foundation of the pavement.
Annexed is a sketch, showing in juxta-position the form of the
street-ways as at present, and as proposed to be; the street is supposed
to be a shop-street, 90 feet wide, having two areas of three feet each,
two footways of 12 feet, and 60 feet of carriage-way; on the section of
the proposed plan a fall of six inches, or 1 in 30, is given from the
shop door to the edge of the pavement; there is then a descent by two
steps of six inches each to the carriage way; and lastly, a descent of 1
in 30, or of one foot to the kennel in the centre of the carriage-way.
The kennel may either be open or covered; if the latter, it must have
many gratings. In the city of Mexico the kennel is chiefly in the centre
of the street, and covered by large flat stones.
On the proposed plan, if we suppose a step from the foot pavement to the
floor of the shop or house, the latter will be elevated about 3 feet
above the gutter, whereas at present we often find it not more than six
inches, and it will readily be admitted that such a difference in the
disposal of the surface-water cannot but keep the houses much drier and
more cleanly.
By having one gutter in the centre of the streets instead of two, (one
at each side,) we remove two sluggish and inefficient kennels, which are
the source of damp to the pavement and to the houses, and we create one
which is at a distance and doubly effective.