• Capabilities: Environmental Solutions, Water Solutions
  • Sectors: Water

Helston Flood Protection

Cornwall, United Kingdom - Helston in Cornwall has a long history of flooding throughout the 20th century and a new solution was needed to reduce the risk and improve the town’s resilience to climate change.

49 homes

protected from flooding

10 ha

of new habitat created

Arcadis was engaged by the Environment Agency to provide detailed engineering design, which included a wide range of environmental services from arboricultural impact assessment through landscape to ecological surveys and planning submission. 

The Environment Agency considered a long list of options for reducing flood risk in the area, ranging from upstream storage, additional flood relief storage and individual property protection. With significant time and cost pressures, the final decision was to build a new emergency outfall culvert that will prevent high water levels building in the large fresh water lake downstream of the town. This will reduce the current risk of flooding to 49 properties.

The area is a designated Special Site of Scientific Interest (SSSI), which meant that the intervention had to be as visually unobtrusive as possible. This will be achieved by minor modifications to the existing intake structure with the remainder of the work being buried from sight.  When required, the outfall will be exposed by the Environment Agency’s in-house operations team and a penstock opened at the intake to allow use of this secondary emergency relief culvert. This option improves control, increases emergency outflows and reduces the risk of flood. It also will have a positive effect on the environment due to an additional 10 hectares of habitat creation around Loe Pool created by lowering the intake’s invert.

The new emergency tunnel will only be used when there are flood warnings for the local area and will divert water to the sea, thereby reducing the likelihood of flooding in the town. It should not only relieve one source of flooding but it will improve water quality in the lake by increased flushing as well.

Work will continue in an effort to further reduce the risk of flooding to properties in Helston and further options will be investigated to find an affordable solution. 

Outcomes

49 homes

protected from flooding

10 ha

of new habitat created

Questions about this project

Simon Bimpson

Managing Director - Water, Energy and Utilities Ask me a question