Rishton's 'high risk' reservoir needs urgent safety works

The problems at the raised artificial lake in Rishton were identified by a 2022 inspection by an independent engineer.

The Canal and Rivers Trust is now seeking prior approval for 'measures in the interest of safety comprising replacement of the existing spillway, earthworks to the existing dam, and an improved vehicular access around the embankment at Rishton Reservoir in Cut Lane off the A678 Blackburn Road'.

It has asked Hyndburn Council to complete the necessary paperwork 'in a timely manner' so the works can be completed swiftly.

In a supporting statement, it tells planners: "Rishton Reservoir is a large raised reservoir of Cut Lane.

The existing spillway at Rishton Reservoir

"The application site comprises an existing vehicular access and parking area off Cut Lane includes the existing reservoir spillway, the reservoir embankment and part of the adjacent agricultural field.

"Rishton Reservoir is designated as a 'High Risk Large Raised Reservoir' under the Reservoirs Act 1976,

"Rishton Reservoir was subject to a Statutory Inspection on April 6 2022 resulting in measures in the interest of safety (MIOS) mandated by the independent engineer as essential for the safe operation of the reservoir."

To fully address the requirements of the MIOS, the Trust is proposing to carry out the following:

• Works to increase the capacity of the spillway. The ability of the reservoir to pass predicated flood flows requires a new improved spillway structure. The proposed new spillway will be located adjacent to the line of the existing spillway and have a slightly larger footprint. The existing spillway channel will be infilled and grassed over to match the appearance of the existing embankment and the existing fence will be removed. The new spillway channel structure will be two metres wide. The scheme will include a 900-millimetre wide pedestrian footpath.
• Improved vehicular access track. The existing vehicular access is made up of a muddy unmade ground surface lading from Cut Lane towards the reservoir. The proposed vehicular access works will consist of a four-metre wide single-lane track surfaced with stone.
• Embankment stability work. The proposed embankment stabilisation work has been developed to raise the crest by 600 millimetres above its existing height with a two-metre wide width. The face of the downstream embankment will be re-profiled by adding surface material so that it is a one-in-three gradient.

The statement adds: "To fully address the requirements of the MIOS, the trust must increase the capacity of the spillway at Rishton Reservoir so that it can cope with the increased flows expected in the future due to climate change."