294 LU EDUOT
gallons per day, caused great anxiety, and shewed the
necessity of largely extended works. It was estimated
that the basin above the Croton Dam, 7 el
339 square miles in area, would give
300,000,000 gallons per day on the
average, if the water could be impounded,
and that, therefore, abundant water could
be obtained by increasing the number
or capacity of the impounding reser-
voirs. New reservoirs were therefore
projected, one of which, to contain
3,000,000,000 gallons, was expected to
be completed in the autumn of 1872.
With this the gross storage would be
4,670,000,000 gallons, in addition to
the daily produce of the Croton River,
which, at its minimum as stated, is _ :
27,000,000 gallons per day. Another g, 47%”;5 Gt
reservoir to contain 3,700,000,000 gal- e
lons was also projected, and will, it is presumed, be con-
structed when necessary (fig. 5). Tomeet the growing de-
ATMILES
Distributing Reservoir
Union Square
Universily
Fra. 5.—Part section of Crotor Waterworks.
mand for water, the reservoirs were not only increased as
described, but the means of distribution were largely ex-
tended, and in one part of the city six lines of pipes 4
feet in diameter were laid side by side.
Manchester Waterworks.
The works by which the city of Manchester and its
suburbs are now supplied with water, and which have
been in course of construction from the year 1848 to
the present time (1874), are perhaps, in some respects,
the most stupendous works of the kind which have ever
been constructed, in which difficulties of no ordinary char-
acter have been successfully overcome. These remarks,
however, relate especially to the impounding reservoirs,
which are seven in number, with embankments varying
from 70 to 100 feet above the level of the valley in which
they are constructed, and cannot, therefore, be properly
alluded to here. As the conveyance of the water to the
city is, however, by aqueduct, a few words explanatory of
the general scheme will be necessary.
The water is collected from the river Etherow and its tri-
butaries, which, rising on the westerly slope of the Pennine
chain of hills, flow into the river Mersey,and so into the Irish
Sea. The drainage ground from which the water is collected
lies nearly midway between Manchester and Sheffield. Its
area is about 19,300 acres. It rises in parts to an elevation
of about 1800 feet above the level of the sea, and about
1200 or 1300 feet above the deep and romantic valley of
Longdendale, in which the main collecting reservoirs are
situated. The district consists of the shales and sandstones
which constitute the lower portion of the Coal Measure
formation—the upper millstone grit forming the cap of
the steep escarpments on each side of the valley, while the
lower millstone grit, which may be said to separate the
Coal Measure shale from the limestone shale, is found in
the bottom. The waters produced by this geological forma-
tion are among the purest in the world. The spring water
is especially brilliant, highly aerated, containing little or
no foreign matter, and extremely soft. Tt is at all times
very abundant, the district yielding much more spring
water than the usual quantity, in proportion to the area
from which the springs issue. The quantity of water
flowing from the drainage ground would, if wholly stored,
afford a gross supply of about 40,000,000 gallons per
day, of which about 13,000,000 gallons per day have to be
delivered as compensation to the mills on the stream,
leaving about 27,000,000 gallons per day as the supply
available for the city and its suburbs.
The water of heavy rains and wet seasons is collected 1n
large impounding reservoirs, the gross capacity of which is
4,933,000,000 gallons. In some of these reservoirs the
turbid and coloured water is impounded, where it is allowed
to settle and purify, and is subsequently given as compen-
sation to the stream ; and in others, the pure water, when
more than sufficient for the wants of the city, is collected.
Here it is stored till required, and then given in addition
to the spring water, when that is in itself deficient in
quantity. The spring water is separately collected, and
conveyed to the city by aqueducts specially constructed
for the purpose. In heavy rains, which swell the streams,
and especially in autumn, the water is discoloured, but by
a simple and ingenious contrivance, every stream is made
to separate its coloured water from its pure water—the
coloured water being passed to reservoirs set apart for the
storage of such water, and the pure water being sent at
once to Manchester, or passed to reservoirs in which it is
stored for future use.
The aqueducts by which this water is conveyed from
the springs and from the reservoirs, consist for the most
part of tunnel and covered conduit, 6 feet in diameter, with
a fall of 5 feet in a mile, with cast-iron syphon pipes of
large dimensions across one valley, which has to be passed
before the highest service reservoir is reached. From this
reservoir to the city, about 8 miles distant, cast-iron pipes
are laid along or under the public roads, to convey the
water to various other reservoirs at lower elevations, from
which the city and its suburbs are conveniently supplied.
In the main valleys in which the spring water is col-
lected, or the flood and turbid waters conveyed by separate
channels, the aqueducts are chiefly open, and are, to a
great extent, formed of concrete 6 inches thick on the
sides and bottom, faced with dry stone pitching 9 inches in
thickness. They are cheap, easily constructed, and per-
fectly successful.
The area and capacities of all the reservoirs are as
follows :—
. |
Name. i Area. : Capacity. Depth. }
|
Acres. Gallons. Feet.
Wioodhead, n i o 135 1,235,000,000 72
Norsides =2 160 1,474,000,000 84
RhodesWiood, sty 54 500,000,000 68
Valetotse, o0 63 343,000,000 40
Bottoms, (estimated) ...... | 46 399,000,000 50
Amfieldisin: e A o e 39 209,000,000 52
Hollingworthye .. oo 13 73,000,000 52
Godileys =i s 15 61,000,000 21
Denton sNoT oo i 7 30,000,000 20
Penton; Nos 2, & i s 6 23,000,000 20
Gorton, Upper; ..o o 34 123,000,000 26
Gorton, i Liowern,. .. ... vl 23 100,000,000 29
Prestwachia . oo 41 20,000,000 22
5991 | 4,590,000,000
Loch Katrine Aqueduct, Glasgow.
The Loch Katrine Aqueduct of the Glasgow Waterworks
is the modern aqueduct which has most prabably attracted
the largest share of public attention.
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