The Liverpool Standard, and General Advertiser.
Liverpool, Merseyside, England, 1854-07-04 00:00:00

al pressure,
to which it is likely

,nly risk to

be guarded against in such a work, the more dangerous
because more insidious and less perceptible risks, arising
from percolation and filtration, require also to be calculated
and provided against ; and on the excellence of this
provision depends nearly the whole stability of the
structure, and of course the value as well as the
safety of the works. The most obvious precaution in
regard to this source of danger consists in the construc-
tion of a water-tight barrier, extending throughout
the whole length of the embankment, and reaching from
a foundation perfectly impervious to water, to a height
considerably above the surface-level of the water to be con-
tained in the reservoir. This water-tight barrier is here, and
generally formed of compactly rammed puddle-clay, and
in the case before us it is of great magnitude, and is care-
fully consolidated by ramming. It is in every portion of
its great length carried down two feet into the solid rock,
which in some places is from 57 to 60 feet below the sur-
face of the valley ; in other words this puddle-wall is in
some places 117 feet in depth, its base being from 14 to
16 feet wide, and gradually diminishing in thickness till
it reaches the top of the embankment with a thickness of
five feet. This embankment, then, with its puddle-wall,
constitutes the restraining barrier to the mass of pent-up
water; the regulated delivery of which is managed by a
built cylindrical tunnel, six feet in diameter, which passes
through the mound near the bottom of the lake and
towards the eastern end of the embankment ; in the mid-
dle of this tunnel is a sluice-valve, by the partial or com-
plete opening of which the flow of water is permitted or
checked. This sluice-valve is reached by a built shaft,
which opens on the upper surface of the embankment.

On the west side of the lake are constructed other sluices
communicating with the waste-wear for running off the
surplus water, and for regulating the supply of compensa-
tion-water to the mills and factories situated below the
water-works. The above description of the Horwich em-
bankment will, in its leading features, apply to the
others, any variation from it consisting more in details
than in geneial principle.

A large portion of that embankment has been
executed, and its farther progress is being rapidly pro-
ceeded with. It has already reached an altitude of 35
feet, leaving about 22 feet to be yet raised ; this portion, it
will be obvious from the preceding description, becomes
rapidly narrower as its height increases, and when it is
borne in mind that the great extra depth of the puddle
wall has been overcome, it will be seen that by far the
largest, as well as the most arduous, portion of its con-
struction has been completed, although not more than nine
months have elapsed since operations were commenced on
it. In addition to the formation, however, it requires also
to be faced with shingling, that is, broken stones, for forty-
two feet up its slope on the side next the water.
Immediately to the south of this embankment, but on
a considerably lower level, a large space has been levelled
and divided by a central embankment running north and
south. On the east side of this embankment the space is
subdivided into six large ponds or filtering beds, while the
opposite or west side is divided into two ; these latter
being the equalising or pure-water tanks. These ponds or
tanks are divided from each other by massive

inbauk-

meats similarly constructed to that already described;

state into the song

delivered into tt

cess of filtration, passing

;hs already me:

the tunnels and sluice-valves,

itioned, and by

em being

The whole of these filte.r-

ing tanks have been made, and the soughs are all con-
structed, while some portions of the rougher filtering
material are in process of being filled in. The sides of

these six ponds are all to be shingle-covered ; and at their
eastern end, but cut off by an embankment from them, is
a channel for running off waste water, when more is run
off from the reservoir than is requisite for supplying the
filter ponds.

The two pure water tanks measure each about 220 feet

a breadth of about 200 feet.

These are to be

paved with thick square-set stones placed on edge, and
firmly cemented in concrete, divided longitudinally into
three floors by stone ridges, VI-lid

oject about a foot

above the general level, a considerabie portion of the floor
of one being already laid. From each of these tanks a tun-