Client: Environment Agency
Location: Corbridge, Northumberland
Contract Value: £0.5 million
Contract Period: December 2008 until April 2009
The works were undertaken within a Site of Special Scientific Interest (SSSI) at Devils Water, Corbridge and were to reinforce the existing flood bank that had previously been breached and over topped by the River Tyne during flood conditions. This caused substantial damage to the south side of the village of Corbridge.
Project Details
The works undertaken were to construct 1,500m of flood defence, comprising clay banks and 3m deep continuous sheet piling to prevent under scour and water seepage from breaching the new defence.
In order to gain access to the site, over one mile of haul roads were constructed in order to supply the operation with the required 6,000 m3 of engineered clay. Using advanced, fully automated, machine controlled GPS Technology we were able to place this fill material in compliance with a detailed 3D design, with minimal interface and to the correct profiles, minimising the fill required and maximising machine efficiency.
Extreme care was required around the existing flood defence to maintain its integrity during construction of the new defence. A flood warning system was put in place to notify the operatives of any potential flooding conditions to allow safe evacuation to the dry side if necessary. All machinery used throughout the works was modified to operate on biological oils, with robust procedures in place regarding a spill event, given the huge environmental impact.
On completion of the earthworks an ecological plan was put in place where over 100 trees were planted, including protection, and the construction of hibernacula (lizard habitats). A new stock proof fence and temporary access track was constructed to allow Environment Agency operatives to safely access and maintain the flood defence asset.
Added Value
Whilst placing the plastic piles a significant archaeological find was uncovered, an ancient Wear was discovered, which served as a historic flood defence for the area. This find raised the profile of the project and resulted in all works being subject to a watching brief with Tyne & Wear Museums.
To add value to the overall project the proposed permanent steel sheet piling was replaced with recycled plastic piles, reducing both cost and the environmental impacts of the scheme on the local environment.
