- 15th July 2016
- Posted by: Joanne Woodhouse
- Category: Projects
The stability of an electricity pylon located on the left-hand floodplain of the River Irwell was placed at risk following significant erosion of the bank during the December 2015 floods. We were commissioned to undertake a geomorphological assessment to advise Electricity North West how best to approach either protecting or relocating the pylon. This involved a site based assessment, hydraulic modelling and liaison with our engineers. Of further concern was the presence of a weir, no longer maintained, immediately downstream of the pylon’s location. Modelling work was therefore undertaken to estimate the impact if the weir were to fail.
A site visit was undertaken to observe processes and the current condition of the River Irwell. Historic maps and aerial imagery were consulted to investigate the historic behaviour of the watercourse. A gradual eastward trend of the watercourse was found, with the impoundment caused by the weir influencing sediment deposition upstream and downstream. It was concluded that the land around the pylon is at risk of continued erosion, which may be further increased initially if the weir were to collapse (by lowering the water level more of the bank would be exposed).
It was recommended that the pylon be re-located away from the channel to reduce the risk, although residual risk would remain. JBA recommended types of bank protection to reduce the risk of scour.
For more information: Matthew Hemsworth