BWB Consulting provided a range of multi-disciplinary services for a new Waitrose store at the historic Wiltshire town of Malmesbury. The food retailer had purchased a 28,000 sq ft site on the outskirts of the town which was intended to accommodate a new 18,250 sq ft supermarket. BWB was appointed by Simons Group to provide flood risk, drainage, geotechnical including on-site supervision of earthworks and civil & structural design.
While the site is at low flood risk, Malmesbury itself has experienced regular flooding and this posed particular challenges through the planning application stage. An added emphasis on public consultation and stakeholder engagement was required to demonstrate that the development would not exacerbate the existing flood risk. BWB co-ordinated extensive consultations with the local residents, flood group and Environment Agency which were fundamental in allowing the development of the site.
Following a six month period of construction the store opened its doors to shoppers in August 2014.
The site was not at risk of flooding but Malmesbury itself is very sensitive to flood events. As the new development would be outfalling upstream of the main historical road bridge over the River Avon which forms a restriction on river flows, it had led to a perception among local residents that the surface water discharge might increase the local flood risk.
BWB carried out an extensive public consultation process, including meetings with residents as well as the EA and Wiltshire Council, to try and explain how the development would not increase flood risk. All flows from the site were being restricted to a low average annual greenfield runoff rate which was demonstrated to be negligible with respect the flood flow rates of the River Avon at times of flood risk.
Further challenges came from the site's steeply sloping nature which BWB addressed by optimising the levels of earthworks. Our Geotechnics team carried out an intrusive site investigation to assess the underlying ground conditions which enabled an earthworks cut and fill scheme to be developed. Following this an investigation was undertaken, which included laboratory analysis of the materials that were to be used, in order to produce an earthworks strategy and specification.
Given the ground conditions and time of year the works were to take place, BWB recommended that lime stabilisation would be necessary to ensure the earthworks were completed to the satisfactory level. During the earthworks our on-site representative ensured the work was undertaken and testing regime followed in accordance with our specification to ensure the final structure would be suitable for the ground.