Flood Risk Assessment for Insurance Purposes: Devon Manufacturing Facility

A large manufacturing business in North Devon commissioned a Flood Risk Assessment following a request from their insurer. The site had no recorded flood history, but the insurer required a formal assessment before the policy could be confirmed. The facilities manager also wanted a clearer understanding of the site’s actual exposure.

This type of commission is common across the commercial and industrial sector. Insurance requirements are often the trigger, but the underlying need is the same: an accurate picture of flood risk, based on site-specific data rather than generic mapping.

The Approach

The assessment was structured across two phases.

Phase 1 comprised the desk-based study. This involved collating EA flood mapping, submitting a formal data request to the Environment Agency for the relevant hydraulic model outputs, and reviewing both fluvial and surface water flood risk for the site and its surroundings. Given the site’s location in North Devon, within the Taw catchment, tidal risk was also within scope alongside fluvial and surface water sources. The site drainage was understood to operate as a combined foul and surface water system, which has direct implications for how the site responds during high rainfall events.

The standard EA flood maps indicated a low risk from rivers and the sea, but maps at that resolution are not suitable for site-level assessment. To obtain meaningful depth data, the EA hydraulic model was requested directly. The LiDAR data available for this location was insufficient for reliable depth prediction, so a topographic survey was commissioned. This produced finished floor levels at eleven node points around the building perimeter, which were then compared against modelled flood levels across a range of return periods.

Phase 2 was the site walkover. The physical inspection assessed the construction of the building, which had been extended and altered several times using mixed materials including brick, concrete and cladding. The interfaces between different construction phases represented potential water ingress routes, alongside more conventional entry points including doors, low-level windows, service penetrations and areas of low-level blockwork. A drainage ditch to the west of the site was noted as overgrown and in need of maintenance, representing an avoidable increase in surface water risk.

Findings

Under present-day conditions, the site is not predicted to be at fluvial flood risk up to the 1 in 100-year return period. At the 1 in 200-year event, the western and northern perimeter of the site enters the modelled flood extent, with finished floor levels at most node points sitting marginally above the modelled flood level.

The future climate change scenario presents a more significant picture. Under the 2115 tidal climate change scenario, a 1 in 200-year event produces modelled flood depths of up to approximately 1 metre above finished floor level at several points around the building. This represents a material increase in risk that requires consideration in any future site planning or alteration work.

Outcome

The assessment satisfied the insurer’s requirements and provided the client with a site-specific understanding of flood risk from all relevant sources. The combination of hydraulic model data, topographic survey and physical inspection produced a more reliable picture than desk-based mapping alone could have provided. Recommendations were made covering maintenance priorities and flood resilience considerations for any future building works.

If your site is in Devon and requires a flood risk assessment, whether for insurance, planning or due diligence purposes, our Devon flood risk assessment service covers sites across the county.