On Wednesday 12th
March Ian Hope, Chair of the British Dam Society, unveiled an evocative
sculpture with annotated plaque to commemorate the 150th anniversary
of the Dale Dyke disaster. This dam failure was the biggest disaster of its
kind in our history and led to the tragic loss of at least 250 lives.
Memorial Plaque Picture
In setting the scene Ian
placed the early Victorian reservoir building programme into context with the
rapid industrial expansion and dire public health needs of the day. Sheffield
itself had suffered a number of well documented cholera outbreaks reinforcing
the demand for safe drinking water and proper sanitation. The Dale Dyke
reservoir was constructed by the Sheffield Waterworks Company following an 1853
Act of Parliament. In stark contrast to
today the Company was not regulated in this activity and was itself able to
design, supervise construction and potentially operate the reservoir without
Immediately on completion of
construction, the "300 yard long, 85 feet high" dam failed on first filling,
exposing inherent weaknesses. The dam was unable to withstand the forces of the
full reservoir which were further compounded by a storm event.
There is considerable
conjecture as to the cause. As engineers our forensic instincts will remain
frustrated! We do know that there were a number of signs we would attribute to
degradation of the core by internal erosion - a "whirlpool upstream" and "cracking of the downstream face". The
dam failed during the night when appraisal under candle light would have been
unlikely to shed light on the true failure mechanism.
The history of the disaster
and post-event hearings brought vested interests and human behaviour into play.
The scene was set for a tense and intriguing drama. Clearly Sheffield
Waterworks Company was protective of its position and commendably did stand by its
employees, principally the Chief Engineer, John Gunsen. Arguably, had the coroner been less zealous with
his corrosive, opinionated, directive approach perhaps the real causes would
have been laid open for analysis.
Whilst there remains scant
evidence as to the true cause of the failure, we are led to question whether
the pressurised pipes through the body of the dam contributed to the failure. We
do know that their presence would have created an inherent threat and later
designs were to avoid this feature.
responsible for later dam construction, adopted a far more conservative
approach to the construction of neighbouring structures. He undoubtedly had a
greater insight as to the cause of failure, being responsible for the
demolition of the remaining Dale Dyke dam structure and able to examine key
features such as the integral pipework. He steadfastedly protected the interests of
his clients and did not publically admit that the Dale Dyke dam had any
defects.These days beyond the
internet more information can be found in Geoffrey Binnie's book "Early dam builders
in Britain" and geotechnical analysis by the late Peter Vaughan. Dr Andy
Hughes, BDS Vice Chair, is conducting a series of talks on the subject (please
see BDS website meetings page for further information).
As an industry we have
learnt a great deal from this and other similar tragic events in Victorian
times. Our confidence in the significantly increased safety of our dams today
comes from the continued vigilance employed by owners and the supervision by
properly trained and qualified engineers who form the membership of the British
Dam Society. The Reservoirs Act 1975 provides further structured safeguards
ensuring the independence of crucial engineering roles which are also detached
from direct employment of the owner. Ian
Hope Chair British Dam Society.
See how the unveiling of the memorial was reported by the South Yorkshire Times here
Watch Ian Hope (British Dam Society) & Newman Booth (Yorkshire Water) explain the background behind the memorial on YouTube here.