43 Apple Grove, Enfield
The Brief
RIDA Reports Ltd was appointed to undertake a detailed flood risk assessment for a proposed residential extension at 43 Apple Grove, Enfield (EN1 3DA). The project involves the construction of new ground and first-floor extensions to an existing single-family dwelling, creating a proposed development footprint of 80.40 square metres within the 262.52 square metre plot.
Why the Client Chose RIDA
Navigating local planning requirements for residential extensions requires a clear understanding of sustainable water management and national planning policies. The client required a specialist consultancy capable of delivering a robust, detailed assessment to evaluate potential site-specific hazards. RIDA was selected for its proven expertise in providing practical drainage solutions and the technical evidence necessary to seamlessly support household planning applications.
The Challenge
The property is situated in River Flood Zone 1, indicating a low probability of fluvial flooding. However, the primary constraint involved safely managing the surface water runoff generated by the new 80.40 square metre building footprint. The challenge was to demonstrate that this ‘More vulnerable’ residential development would remain safe over its lifetime and that the increased impermeable area would not result in surface water exceedance events or exacerbate flood risk to neighbouring properties.
The RIDA Difference
RIDA conducted a detailed flood risk assessment, evaluating the site against Environment Agency flood maps, local council data, and CIRIA ‘Designing for exceedance in urban drainage’ (C635) guidelines. To directly mitigate the identified surface water runoff risks associated with the new footprint, the team formulated a site-specific Sustainable Drainage System (SuDS) strategy. This involved designing and specifying a dedicated soakaway system (1.2m deep x 1m wide x 1m long) located in the rear garden, ensuring that rainwater is safely captured and infiltrated into the ground, thereby replicating the site’s natural drainage regime.
The Outcome
The detailed assessment successfully demonstrated that the proposed extensions could be safely accommodated on the site. By integrating the targeted garden soakaway to manage surface water runoff, RIDA ensured the development would not increase flood risk elsewhere. The comprehensive report provided the robust, National Planning Policy Framework (NPPF) compliant technical justification required to support the client’s planning application.