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Caution over new reservoir inspection plan

Engineers said this week that they feared that new government plans to tighten the reservoir inspection regime are unworkable.

They said that trebling the number of dams covered by legal inspection requirements to around 7,000 would result in many slipping through the net.

The proposals are part of the draft Floods & Water Management Bill, published by the government last week. They are part of the effort to implement recommendations made in Sir Michael Pitt’s independent review of the summer 2007 floods.

Engineers warned that the plan could fail because of the logistics of registering the reservoirs.

“It will require a significant amount of effort to find the owners [of the reservoirs to register them],” said Atkins director of dams and reservoir engineering Andy Hughes.

He warned that the government would face the same problems that followed the  passing of previous reservoir safety Acts in 1930 and 1975.

“It didn’t happen then and it won’t happen now. When you’re talking about finding another 5,000 reservoirs, it’s so difficult. Many will be very small – and they could be privately owned or abandoned,” said Hughes.

The new plan would update the current system, which covers 2,092 reservoirs that hold, or are capable of holding, more than 25,000m3 of water above the natural level of land adjoining the reservoir. The amendments to the draft Bill, say that reservoirs with a minimum capacity of 10,000m3 would be added to the register – the Environment Agency estimates this would be another 5,000.

It states: “Raised reservoirs with a capacity of less than 25,000m3 potentially pose similar dangers [as reservoirs with over 25,000m3 capacity] to people living immediately downstream.”

But an Environment Agency spokesman said that not all of the additional 5,000 dams would be such high risk structures that their failure would kill people.

“As a result they would not require the same level of engineering or assessment,” he said.

The ICE  agreed and said that in the long term it did not expect the number of inspections to change as some structures would only need limited monitoring.

“Although there will be an examination of all of the reservoirs, our understanding is that there should not be a great overall increase in the number subject to control,” said ICE reservoir committee secretary Paul Taylor.

“For example, the method of dam construction might make a difference.

“Modern concrete dams pose virtually no risk at all, while earth embankment dams constructed in the 19th century could pose considerable risks.”

Hughes added that while the draft Bill could throw up problems, the profession would welcome suggestions to improve safety as well as the increase in work available to engineers for assessing reservoir safety.

Proposed registration requirements:

  • Details of how the reservoir manager monitors its safety
  • An inundation map showing flooded areas in event of an uncontrolled release of water
  • Name and address of the owner
  • Limited technical information – including grid reference, height, volume, type of construction

Readers' comments (1)

  • LIVING IN A SMALL COMMUNITY WHERE BRISTOL WATER INTEND TO BUILD A SECOND 65+ CAPACITY RAISED RESERVOIR WHICH ALONGSIDE THE ORIGINAL ONE WILL IN EFFECT BLOCK THE TOWN BETWEEN RESERVOIRS AND THE MENDIPS CAUSES GREAT CONCERN. IF ONE SHOULD BURST AND THE WATER PRESSURE HIT THE SIDE OF THE SECOND RESERVOIR WOULD THAT NOT IN EFFECT CAUSE A TSUNAMI TYPE SITUATION? I AM OF THE OPINION THAT IF THE SECOND RESERVOIR SHOULD GO AHEAD THE POTENTIAL LOSS OF LIFE WOULD BE UNTHINKABLE. WOULD THEY BE ALLOWED TO DO THIS UNDER PROPOSED KLEEGISLATION?

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