Client: Residential Property Owner in Trafford.
Scheme: Demolition of existing commercial building and construction of a new dwelling.

The Challenge: Risk of river flooding for new dwelling.

Ashfield was commissioned to conduct a Flood Risk and Drainage Assessment for the demolition of existing commercial buildings and the construction of a new dwelling in Trafford, Greater Manchester.

With two main rivers in close proximity and the site situated within Flood Zone 3, indicating a potential risk of fluvial flooding, a comprehensive assessment was essential to support the planning application.

Our Approach: Mitigation measures based on Environment Agency flood model data.

Ashfield conducted a site-specific Flood Risk Assessment (FRA) in line with the latest local and national policies.

This involved comparing the on-site topographical ground levels with the Environment Agency’s flood model data. From this analysis, the site was projected to be at risk of river (fluvial) flooding during the 1 in 100 year + 70% allowance for climate change in the defended scenario.

However, the site was not indicated to be impacted during the design 1 in 100 year +35% climate change event in the defended scenario, which is a promising sign when applying for planning.

Therefore, Ashfield recommended several mitigation measures to manage the residual flood risk as part of the development’s design.

Outcome: Planning permission was granted

Despite the residual risk of flooding from two nearby rivers, Ashfield successfully provided mitigation measures for the development.

These included:

Setting the finished floor levels (FFL) at a specified height
Implementing flood-resilient measures
Identifying safe evacuation routes with no detrimental flood impact elsewhere.
Developing a comprehensive flood warning and evacuation plan.

Planning permission was granted on the condition that the development follows Ashfield’s approved FRA, incorporating the proposed flood-risk recommendations and evacuation plan.