Client: Environment Agency
Location: Northumberland
Contract Value: £0.27 million
Contract Period: February 2009 until April 2009
The works to Haydon Bridge, which is a Specialist Site of Scientific Interest (SSSI), were carried out to renew the existing flood defence wall due to it being outflanked by rising water from the South River Tyne during the serious flooding in 2005.
The project consisted of the removal of an existing flood defence wall and in its place, the construction of a new flood defence wall approximately 400 meters long constructed along the existing line of foundation. The construction method adopt was groundbreaking, and the first time that the Environment Agency had used one tonne, interlocking blocks, which are molded from concrete with a weathered.
Finish giving a natural stone finish to adapt to the existing environment. The wall was constructed to almost double the size of the existing flood defence wall, measuring 380m in length protecting 23 properties.
Prior to commencement of works tree removal was required to gain access to the site. This was carried out by specialist sub-contractors and managed by our site team. A CCTV conditional survey was then carried out to the existing drainage network adjacent to the wall to assess its condition.
Due to the close proximity of the site to residential dwellings a good relationship was formed from the outset to ensure smooth lines of communication between ourselves and the residents. To develop this relationship the offset trees from the felling works were chopped into logs and distributed to the local community to use as fire wood.
As the works involved the removal of the existing aging concrete flood wall the integrity of the flood bank had to be maintained at all times. This was achieved by forming a temporary clay bund. As construction of the new flood defence wall progressed this temporary bund was removed accordingly.
To begin the construction of the new flood defence wall the existing trench was excavated and a concrete base blocks installed with an insitu concrete surround laid upon a damp proof membrane. The interlocking Redi-Rock concrete building blocks were then placed upon foundation on a motor bed. Once the flood defence wall had been built to the required height an interlocking coping stone was installed to all the top of the wall. As part of this process numerous stair cases were built using the same construction method to allow access for home owners to their gardens. Landscaping to either side of the wall was then undertaken with construction of footpaths and erosion controlled, pre-seeding matting installed to the wet side of the flood wall to create a naturally looking grass covered river bank.
During recent flooding the new flood wall was tested by rising river levels. This proved to be very successful due to no flooding incidents. Due to this new construction method being undertaken and successfully completed various media sources reported on the scheme. This was carried out in the form of coverage in local newspaper articles and local radio interviews.
