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Rock Ramp Perturbation Fish Pass

This project was to construct a rock ramp perturbation fish pass at the site of twin weirs enabling migratory fish to access the upper River Ouse once again.

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    The upstream temporary dam and pipework from two of the pumps.
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    The downstream temporary dam and a diesel pump dealing with the seepage through it.
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    The formwork is constructed around the base of the boulders prior to the final concrete pour to secure them in place.
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    The boulders in place before final concreting looking upstream.
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    The commissioned fish pass.
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Two temporary dams were installed to divert the entire flow of the river over the right bank weir leaving the left channel dry for the construction of the fish pass.

Two diesel and two electric submersible pumps were used running 24 hours to keep the working area dry for the duration of the works.

The channel was excavated in order to construct the base for the fish pass. Once this had cured the boulders were imported and placed out before being set in concrete.

The upstream and downstream ends of the fish pass were protected with a smaller grade of rock.


The Environment Agency

Guildbourne House, Worthing


Sharpsbridge, Uckfield, East Sussex

  • Armorloc interlocking concrete blocks
  • Granite rip rap stone
  • Imported crushed stone
  • Woven geotextile