Dubbs Impounding Reservoir Remedial Works

This contract was undertaken to provide additional overflow capacity to the large raised impounding reservoir at Dubbs IR in Cumbria to enable it to safely pass the probable maximum flood (PMF).

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This contract was undertaken to provide additional overflow capacity to the large raised impounding reservoir at Dubbs IR in Cumbria to enable it to safely pass the probable maximum flood (PMF).

The substantial remedial works consisted of:

  • New spillway channel and apron
  • New auxiliary overflow weir
  • New reinforced concrete core wall clad with stone 
  • Raising levels of reservoir wall at non overflow areas
  • Re grading and strengthening of embankments
  • New land drainage and flow meter chambers

The environmental constraints and contract requirements were considerable given that the site is designated as a SAC (Special Area of Conservation), a higher environmental grade than SSSI.

EWCE successfully completed the works achieving Zero pollution issues throughout the contract in spite of the following issues:

  • The works were located directly upstream of a stream containing freshwater pearl mussels and white clawed crayfish
  • Water quality was measured twice daily throughout the contract period at four specified locations without a single instance of non-compliance
  • Site was intensively monitored by external environmental specialists from United Utilities, the EA, the Lake District National Park and Natural England - all were extremely satisfied with the environmental management of the site
  • Adders (snakes) found on site were captured by a specialist and relocated to a purpose built hibernaculum.

Client: United Utilities

Contract: Dubbs Impounding Reservoir Remedial Works

Value: £400k

Duration: 25 Weeks