This design and build ECI contract was delivered in two phases, with the purpose of this scheme being to divert floodwater to the River Wye before it reached Hereford town centre.
The first phase began in October 2010 and involved geotechnical investigation, completion of detailed design, along with input from stakeholders, archaeological investigation and discharge of planning conditions. During this phase, public exhibitions and liaison with the local landowners was also carried out to inform the local community of the proposed works.
In the second phase Dawnus completed a temporary diversion of Yazor Brook in order to construct a 30m long masonry clad reinforced concrete outfall structure, with associated retaining walls and 1.4km of 2m diameter culvert. Works also included construction of a 70m long reinforced concrete spillway and energy dissipation chamber prior to the flows returning to the River Wye across the re-graded floodplain.
Construction of the culvert required crossing the A438 Trunk Road, installing a 200m section within a 4m corridor to minimise disturbance to archaeological remains, whilst the spillway was installed within a 6m deep propped sheet piled cofferdam to retain significant trees located within National Trust Land.
Successful management of extensive ecological and archaeological mitigation measures was a central element of this scheme, along with significant re-use of site-arising gravels to produce primary aggregates. The scheme consequently achieved CEEQUAL Very Good with a score of 72.6%, just 2.4% off an excellent award, with the recycling works making a significant contribution to the award scoring.
Dawnus worked with the adjacent Football Club and Community centre to include community benefits within the solution, securing additional town centre improvement works as a result of successful delivery of this flood defence scheme.