|
Heavily locked canal routes are often vulnerable in times
of drought and the Huddersfield Narrow Canal became notorious
in this respect. Outram initially proposed feeder reservoirs
'to contain 14,900 locks-full of water to supply one hundred
locks per day for four months altogether', claiming this
was more than enough for the largest trade that could be expected,
and that with this 'capacious system' there was no need to
tap the rivers in the dry season and thus deprive the mills
of vital supplies. In spite of this claim the cautious weavers
still insisted on increasing total capacity to 20,000 locks
full.
Brown's original survey showed a reservoir at Stayley Mill,
another near Saddleworth Church, three in the Wessenden Valley
above Marsden and others at March Haigh, Diggle and Slaithwaite.
Only the last three were built by the company. The Wessenden
chain was completed before 1800 by a consortium of mill-owners,
although the system was taken over eventually by Huddersfield
Corporation and developed for potable water supply. A location
on Swinshore Common was eventually preferred to that at Staley
Mill, although this was also abandoned after its partial destruction
during the floods of 1799.
Reservoirs were built as the canal sections were completed
and opened to traffic. Thus Slaithwaite reservoir was being
built in 1796 as the canal approached from Huddersfield, to
be followed by a new reservoir at Tunnel End, above Marsden,
in 1798. These were soon followed by March Haigh and Red Brook
reservoirs which used to augment the Tunnel End supply via
the Red Brook and its tributaries. Similarly that at Diggle
was under construction in late 1799 to provide for the section
from Stalybridge to Woolroad.
All reservoirs were contained by earth dams with clay cores,
although the design and construction methods are unknown.
Most leaked for several years after completion and this can
no doubt be attributed to ignorance of the engineering principles
involved, lack of suitable plant for consolidation and, perhaps,
also to the absence of skilled supervision. The state of the
reservoirs on the summit level in 1800 was said by Rooth to
be so bad 'that there was not one reservoir out of five that
would retain any water' and 'there was a fairly well-grounded
apprehension of great destruction to the property of the country
below the Slaithwaite dam'.
In 1807, Black Moss reservoir was under construction on
the watershed of the Colne and Tame valleys such that flow
could be directed into either valley as required. Thomas Telford
also recommended that another reservoir should be constructed
close by at Swellands, which he stated would be of 50 acres
and 45 feet in depth. A small capacity reservoir at Sparth
in the Colne Valley was constructed in 1807 to complete the
original supply system for the canal.
Work seemed to be drawing to a conclusion when a very serious
accident occurred with the failure of Swellands dam on 29
November 1810. The reservoir was then only partially filled
with water to a depth of 7 feet but this proved sufficient
to cause the underseepage and collapse of the earthworks.
Water rushed eastwards into the Colne Valley at one o'clock
in the morning inundated the valley at Marsden and as far
beyond as Paddock. The force of the water was such that a
15 ton boulder was washed two miles from the summit and the
mountainside was denuded of soil. Factories and homes were
destroyed in what became known as the night of the black flood.
|
