Flood Risk Assessment for Major Development
Planning Evidence for Major Development
Our Flood Risk Assessment for Major Development service provides the robust planning evidence required for larger and more complex developments. RIDA combines experienced flood risk consultants, fast response times and competitive fees to help identify constraints early and keep your application moving. We provide clear, practical advice and reliable assessments tailored to your development and local planning requirements. Flood risk and coastal change Planning Practice Guidance
Get A Free No Obligation QuoteEnvironment Agency Flood Map for Planning
Send your site boundary, proposal details and planning information so we can define the assessment scope, technical inputs and fee.
Get A Free No Obligation QuoteWhat You Will Receive
Technical Deliverables
| Technical deliverable | Purpose |
|---|---|
| Site-specific FRA and flood source review | Provides technical evidence for your planning submission. |
| Flood mapping and available data review | Identifies relevant constraints and information gaps. |
| Climate change, mitigation, residual risk and safe access assessment where relevant | Sets out proportionate measures for the proposed layout. |
| Drainage coordination notes | Connects flood risk findings with SuDS, runoff control and exceedance routing. |
| Calculations, model review or modelling outputs where scoped | Provides further evidence for sites requiring detailed assessment. |
| Final report package and agreed response support | Supports submission and replies to technical comments within the agreed scope. |
Drainage, Modelling and Consultee Coordination
Flood Risk and Surface Water Drainage
For major development, flood risk and surface water drainage often need to be considered together. RIDA can coordinate the Flood Risk Assessment and drainage strategy so that proposed levels, runoff rates, SuDS, exceedance routes and mitigation measures form a consistent planning submission. Where drainage evidence is required, our team can develop the strategy alongside the FRA, helping to identify potential issues early and reducing the risk of conflicting information or avoidable requests for further information.
When Further Technical Work May Be Needed
Some major developments require more detailed assessment where existing flood information is limited or the proposed development could affect flood levels or flow routes. RIDA can review the available evidence and advise whether flood modelling or additional technical work is proportionate to the planning requirements. flood modelling support | Lead Local Flood Authority requirements
What We Need to Scope Your Assessment
- Site address, postcode and red line boundary to review the planning and flood context.
- Proposed use, development area, unit numbers and drawings to define the assessment scope.
- Planning reference, validation request or consultee comments to identify requested evidence.
- Existing FRA, drainage strategy, topographical survey, ground investigation or model data to avoid duplicated work.
- Target submission date to plan the agreed work.
check the long-term flood risk for an area | flood risk assessment costs
Major Development FRA FAQs
Do I need a flood risk assessment for a major development?
An FRA is commonly required for sites in Flood Zones 2 or 3 and Flood Zone 1 sites over one hectare. Other triggers can arise from surface water, groundwater, ordinary watercourses or local planning policy. RIDA reviews the site and proposal before confirming scope.
Do I need both a flood risk assessment and a drainage strategy?
Many major development applications need both. The FRA assesses flood risk to and from the development. The drainage strategy sets out how surface water will be managed. The documents should use consistent levels, layouts, discharge assumptions and mitigation measures.
Can RIDA work from existing drawings, surveys or flood data?
Yes. Send all current information for review. RIDA will identify what can be used and flag missing surveys, calculations or model data before agreeing the scope.
What affects the cost and programme of a major development FRA?
Key factors include site size, flood sources, data availability, design maturity, drainage coordination, survey needs and hydraulic modelling. RIDA confirms the required inputs and fee after reviewing your information.
Request a Major Development FRA Scope
Send your site boundary, development details, drawings, planning information and target date. RIDA will identify the proportionate FRA, drainage and modelling inputs before work begins.
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