Kennet & Avon Canal dredged to help water voles

As part of a £600,000 project on the Kennet & Avon Canal, which celebrated turning 200 years old in December 2010, a 2.5km stretch of waterway embankment near Hungerford in Wiltshire will be rebuilt.

The modern day canal builders are looking back to the ideas of the canal’s original creator, famous civil engineer John Rennie, to help them come up with solutions to modern day problems. One important issue is how to create natural looking, stable canal banks that are also water vole friendly.

British Waterways’ senior project engineer, Antonia Zotali explained, ‘This winter British Waterways, in partnership with Natural England and the Trustees of the Town and Manor of Hungerford, is rebuilding stretches of the waterway banks near Hungerford as part of its continued work to maintain the nation’s historic waterways.

‘The banks have, over the years, been eroded by boat wash, cattle grazing, soil conditions and even burrowing invasive crayfish. It would be very easy to just say we are going to rebuild the banks using concrete and steel, but this wouldn’t reflect the special canal heritage and environment so we are using more natural methods to do the job.’

The canal banks are being rebuilt by recycling the sediment dredged from the bottom of the canal. Dredging is done to help keep the canal navigable for boats and, in this scheme, provides the perfect material for rebuilding the canal banks. The freshly dredged material is held in place by a below water level shelf , supplemented by a reed planting scheme which includes a line of tussock sedges, just as John Rennie did 200 years ago.

British Waterways’ ecologist, Oda Dijksterhuis said, ‘Tussock sedges are brilliant plants to use as part of this scheme to rebuild the waterway banks. By planting the sedge we will create a fringe of greenery along the water’s edge. John Rennie originally planted tussock sedges when the canal was first built because as the plant grows, and its roots form, they help to knit the soil and sediment together, stopping erosion and defending the bank.’