Flood risk case study: Norfolk Street, Boston

Overview

We developed a land led scheme of 47 dwellings on a site in the centre of Boston. Designated as being in flood zone 3, the site was at risk to breaches of existing local tidal flood defences. The site levels were around 2.85mAOD. The flood risk assessment calculated that the breach of the tidal flood defences would overtop to a depth of 3.50m. Therefore, the plots within the site were designed with a finished floor level of 3.60mAOD. Plots fronting Norfolk Street were set lower to suit the existing road levels, but there wasn’t any habitable ground floor accommodation. Low permeability building materials were specified, with all ground floor electrical connections dropped from the ground floor ceiling. Residents were registered with the EA flood warning service. The increase in finished floor level when compared to existing levels was achieved through a combination of raising site levels and providing ramped and stepped access to homes.