This was an Environment Agency project, which required the construction of a water retaining earth dam across the River Wansbeck to prevent flooding in Morpeth, Northumberland.
Works included the provision of a Temporary River Diversion Channel to change the course of the river during construction of a series of concrete culverts, which are located within the existing river channel. Once in place the culverts were then overlaid with an engineered clay dam stretching across the Wansbeck Valley.
The River Wansbeck is the only river in Northumberland that still contains a healthy population of the native White Clawed Crayfish, which are a protected species. Environmental measures were implemented to ensure the wellbeing of the crayfish during construction of both temporary and permanent structures and to prevent the spread of crayfish plague, which is carried by the non-native Signal Crayfish. The river is also home to otters, kingfishers, salmon, sea trout and eels.
Once diversion works were completed, a row of six culverts was installed within the river bed with specialised culverts for crayfish and salmon. The main culvert sections are 3m high x 3m wide x 2m long and a total of 145 culvert sections were installed. On completion, concrete headwalls were built to house sluice gates at the upstream end of the dam, which close automatically as water levels rise.
The earth dam structure comprises of 73,000m3 of engineered clay built over the culverts and ties into the existing valley slopes at either side of the river. The dam retains approximately one and a half million m3 of water.
