Teton Dam Failure 1976
By group 22
•Gavin Kerr
•Conleth O'Connor
•Paul Watters
•Jonathon Craig
Introduction
The Teton Dam was designed and built as a
multi-purpose reservoir.
It was to provide
• Irrigation
• Water
• Flood prevention
• Electricity
• Recreational water facility
The Design
The Dam was 97m deep and 975m wide which
enclosed a reservoir which spread back for 27km.
The central core was composed of
• Sand
• Silt
• Clay
• Gravel
• Cobbles
Which engineers believed to be impervious to water.
The core was protected by layers of overlying rock
What happened?
The dam collapsed on the 5th June 1976 when
the reservoir was approaching full capacity.
Although two days previous to this, engineers
had noticed springs in the right abutment
downstream from the dam.
What happened?
Observers noticed a wet patch that morning on the
downstream face of the dam
This wet patch soon turned into seepage and surface
materials began to collapse
As the reservoir grew, so did the hole and eventually
the crest of the embankment fell through and the
water surged through the gap
How did it happen
The rock used in the presumed to be
impervious core contained small faults that
weren’t deemed to be large enough to cause
any problems
As the water behind the dam increased, the
greater pressure created, forced these small
faults to open and allowed for the seepage
which incurred
The main causes
Unfortunately rash and unwise governmental
and political decisions were deemed the
driving force behind the dams failure
Senators seeking re-election believed by
providing such a huge water reserve, it would
boost their chances of returning to office
Causes…
Politicians overstated benefits and understated
costs which led to vital areas of the dam
construction being overlooked
Bureaucracy played a huge part in hurrying the
project along before and during construction
However…
Ultimately it was decided it was the fault of the design
team
Geologists testified that poor site selection and
inadequate approach to design and construction led
to the failure
High permeability, porosity and frailty of the material
under the dam greatly contributed to the failure of
the tetra dam
Lessons learned
It was decided that for successful dam construction
changes needed to be made
• Peer review studies for dams
• Ensuring redundant measures to control seepage
and piping
• Special treatment for fractured rock foundations
• And finally frequent site visits during construction by
the design engineers
28/10/04
Thank you!!!!!!!!!!!!!!!!!