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Dam Problem


Upon hearing the reports of a problem on an impounding dam I looked on with interest when the helicopter shots were broadcast.

Yes, severe scour had reduced the safety of the embankment and yes, I am sure that Jim Claydon, the Panel All Reservoirs Engineer, had very little option but to clear the flood route in the immediate aftermath.

But I have two questions.

Was there an emergency draw off valve built into the dam in 1874? If not, why was an emergency siphon not retrofitted? It always annoys me to see diesel pumps being used in an emergency instead of a couple of large diameter siphons.

The media coverage of this problem has also set back my negotiations with several district councils on reservoir developments because the Environment Agency Development Control now insists on a dam break report for every retaining structure.

As a result, councils naturally think that this is now a probability.

I am not aware of any dam breaks in the UK in the last 40 years. However, in December 1999, a Boeing 747 aircraft crashed into an impounding reservoir shortly after take off from Stansted. The main embankment, similar in design to Ulley but only 5m high, took the full force of the impact. The result was five craters of about 3m deep and 6m across each and no leakage from the reservoir.

On this basis it is more relevant for the Environment Agency to insist on a 747 impact report than a dam break report.

Andrew Hawes, Supervising Panel 1975 Reservoir Act, 11 Church Walk, Aldeburgh, Suffolk, IP15 5DU

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