Cheltenham's flood risk reduced
Safer working was one of the benefits of an innovative approach to flood management in the Gloucestershire village of Prestbury, says Craig Burrows of Asset International
In response to severe flooding which hit England in 2007, an extensive project to reduce the risk of further flooding was commissioned to improve the flood water management in the village of Prestbury, near Cheltenham in Gloucestershire. The scheme, costing £1.5M in total, involves connecting two existing flood relief culverts and creating a bypass pipeline using Weholite structured wall pipe, manufactured by Asset International.
The project is a collaboration between the Environment Agency, Gloucester County Council and Cheltenham Borough Council. It is being delivered by Birse Civils and was designed to manage peak flows from the nearby Mill Stream and Noverton Brook.
The initial design of the scheme, during the planning application stage, included an open channel with a series of culvert crossings on roads to act as a bypass channel. Due to the nature of the topography, following further detailed surveying, it was not feasible to excavate and build a suitably sized open channel across grazing fields as it would have significantly increased the landtake and created safety issues.
Asset worked with civil engineers Royal Haskoning and Birse Civils, a division of Balfour Beatty Regional Civil Engineering, during the ECI design stage, providing feedback on their preliminary sketches. When Birse was appointed, Asset was able to provide them with the Weholite solution.
The high-density polyethylene (HDPE) pipe, which is manufactured at a facility in Newport, South Wales, allowed for a quicker, easier installation and reduced the requirement for landtake. Asset supplied 500m of 1.2m and 1.35m diameter pipe and a number of prefabricated 2.2m and 2.5m oversized manholes.
Terry Tuck, agent for Birse Civils, says: "We were really impressed with Asset's bespoke flood alleviation solution. There were many advantages to using Weholite over more traditional methods in terms of making the installation easier and safer for my team and more economical for the customer.
"One of the biggest advantages was that the manholes were pre-fabricated offsite, which reduced the need for confined space working and reduced the need for people to enter excavations. The manholes and pipes were light and easy to transport, as well as easy to store, as we can double stack them. The manhole excavations were backfilled quickly, shortening the time required for the job."
Work began on the project in February 2011 and on completion will reduce the risk of flooding to a 1-in-100 chance for 57 homes in Prestbury. Craig Burrows, technical sales engineer at Asset, says: ''By working in partnership with the Environment Agency and Birse Civils we have developed a flood alleviation system that will keep the homes in Prestbury safe from flooding for the significant future.
"Once again our ability to offer a range of bespoke solutions, with them all fabricated offsite, has allowed us to provide exactly what the project needed as well as the additional benefits of easier installation and storage. The fact that we can nest the pipes cuts down on the vehicles needed for transportation, which helps reduce cost as well as lowering the project's carbon footprint."