Westmeads Community Infant School
The Brief
The project involves the siting of a new 66m² mobile classroom, along with a ramp, timber pergola, and external decked area, to provide nursery provision within the existing boundary of Westmeads Community Infant School. Located on Cromwell Road in Whitstable, the proposed development is situated on the school’s current external playground. A detailed flood risk assessment was required to evaluate the site and support the planning application for this minor educational development.
Why the Client Chose RIDA
The client required specialist engineering expertise to navigate the strict national planning policies associated with developing educational facilities in higher-risk flood zones. RIDA was chosen for their ability to deliver a detailed flood risk assessment that could provide clear, pragmatic mitigation strategies while ensuring full compliance with the National Planning Policy Framework (NPPF) to support the planning application.
The Challenge
The primary constraint for this site was its location within Environment Agency Flood Zone 3, which indicates a high probability of tidal flooding. While the site benefits from existing flood defences and has a low risk of surface water flooding and a very low risk of groundwater flooding, the predicted extreme tidal water levels necessitated careful planning. Furthermore, although the minor scale of the development (under 250m²) exempted it from the Sequential and Exception Tests under NPPF standing advice, it still required a robust strategy to protect the highly vulnerable future users of the nursery and manage potential inundation without increasing flood risk elsewhere.
The RIDA Difference
RIDA conducted a detailed flood risk assessment to evaluate the tidal threat and establish appropriate site-specific mitigation measures in strict accordance with NPPF guidelines. To address the high tidal flood risk, the assessment determined a design flood level of 2.8m AOD and recommended setting the finished floor level at 3.1m AOD to provide a 300mm freeboard safety margin. Because the foundations and lower structural elements would still interact with potential floodwaters, RIDA outlined a ‘water exclusion strategy’ utilising flood-resilient construction materials—such as engineering bricks, cement-based mortars, and closed-cell insulation—for all construction up to 3.4m AOD. Additionally, to ensure the immediate safety of students and staff, a clear evacuation route was mapped out directing users toward higher ground on Westmead Road, and the implementation of a formal Flood Warning and Emergency Response Plan was advised.
The Outcome
The detailed flood risk assessment successfully demonstrated that the proposed nursery provision could be developed safely and sustainably. By incorporating the recommended finished floor levels, resilient material specifications, and emergency evacuation planning, the assessment confirmed full compliance with NPPF guidelines. Ultimately, the report provided the necessary technical evidence to support the planning application, proving that the development would safely manage its flood risk for its 50 to 100-year design life without increasing flood risk to the surrounding community.
