FLOOD RISK ASSESSMENTS
Pragmatic, Policy-Led Flood Risk Assessments
Flood risk is often described as a "dark art" — and for good reason. Delivering a robust Flood Risk Assessment (FRA) means navigating a complex web of national policy, guidance, and technical standards. At Enviren Ltd, we bring clarity to that process. With a near-100% approval rate, we are trusted by developers, planners, and Local Planning Authorities.
REGULATORY COMPLIANCE
The Policy Backbone: NPPF & PPG
The NPPF (December 2024 update) requires all development to avoid areas of flood risk wherever possible. It mandates the use of the Sequential Test to direct development to areas of lowest risk, and, where unavoidable, the Exception Test to demonstrate that development will be safe for its lifetime and provide sustainability benefits.
The PPG: Flood Risk and Coastal Change expands on these requirements — setting out when FRAs are required, how to consider all sources of flood risk, apply climate-change allowances, and account for residual and emergency planning considerations. At Enviren, every assessment we produce adheres to these principles, ensuring that applications are technically robust, policy compliant, and ready for submission.
STRATEGIC APPROACH
Sequential and Exception Tests
The Sequential Test and Exception Test are central to national flood risk policy. The Sequential Test ensures development is located in the lowest-risk areas first, starting with Flood Zone 1 before moving to Zones 2 or 3. Where there are no suitable alternatives, the Exception Test must be passed — demonstrating that the proposal provides clear sustainability benefits to the community, and will be safe for its lifetime without increasing flood risk elsewhere.
Enviren Ltd excels at applying these tests pragmatically and persuasively. Our engineers combine detailed hydrological data, EA modelling, and planning context to produce robust Sequential and Exception Test reports that satisfy both the LPA and the Environment Agency. We reference Strategic Flood Risk Assessments (SFRAs), local plan allocations, and catchment-specific guidance, ensuring that every justification aligns seamlessly with both national and local flood risk frameworks.
Sequential Test
We ensure development is directed to areas with the lowest probability of flooding, using EA flood maps, SFRA data, and local plan evidence.
Our approach balances technical compliance with commercial viability, helping constrained sites proceed confidently.
Exception Test
Where Sequential Test cannot be satisfied, we demonstrate clear sustainability benefits and prove the development will be safe for its lifetime.
We prepare compelling evidence using detailed modelling, design levels, and emergency planning measures.
TECHNICAL EXCELLENCE
Expertise in Complex Flood Zones (2 & 3)
For developments within Flood Zones 2 and 3, Enviren undertakes a detailed, evidence-based analysis that ensures full compliance with EA requirements and NPPF policy.
High-accuracy topographic survey — used to compare finished-floor and site levels (mAOD) against modelled flood levels and exceedance routes.
Environment Agency datasets — requested through the Flood Map for Planning service, including detailed model outputs (historically "Product 4") and defence data (now through the AIMS Spatial Flood Defences database, formerly "Product 8").
Climate-change allowances — application of the EA's latest guidance for peak river flows, rainfall intensity, and sea-level rise, selected according to vulnerability class and development lifetime.
Residual risk & freeboard — application of the EA's SC120014 freeboard update, ensuring confidence in level design and mitigation measures.
Safe access and egress — assessment of hazard to people (depth × velocity + debris factor) using DEFRA/EA methodology FD2320/TR2, ensuring safe evacuation and compliance with local emergency-planning requirements.
UNDERSTANDING RISK
Comprehensive Coverage of All Flood Sources
Every FRA produced by Enviren considers all sources of flood risk. This holistic approach ensures that flood risk is fully understood and mitigated across all pathways.
Fluvial & Tidal
From rivers, estuaries, and the sea, using EA modelling and historic flood data.
Surface Water
Pluvial flooding assessed using national RoFSW datasets and local drainage mapping.
Groundwater
Evaluated with specialist hydrogeologists and aligned with LLFA standing advice.
Sewer Flooding
Informed by asset records and network performance data from water companies.
Reservoir Risk
Assessment where applicable using EA reservoir flood maps and breach scenarios.
Climate Change
Latest EA allowances for peak flows, rainfall intensity, and sea-level rise.
OUR PROCESS
Transparent, Efficient, and Approval-Ready
Front-Loaded Viability
Before quoting, we review EA data, flood zones, modelled levels, and SFRA mapping to identify the most efficient path to compliance.
We Manage Coordination
We liaise directly with the EA, LLFA, and contractors to obtain all required data, surveys, and testing. Clients stay informed but never burdened.
Submission-Ready Reports
Every FRA includes policy references, design-level mapping, and clear visuals that align with the NPPF, PPG, EA guidance, and local templates.
Local Policy Integration
We tailor each report to the latest LPA and LLFA standards, referencing recent Sequential and Exception Test notes and local FRA checklists.
Why Choose Enviren
35+ Years Experience
Combined civil and environmental drainage design expertise
National Recognition
Expertise in SuDS, nutrient neutrality, and off-mains systems
Full Compliance
Designs satisfy NPPF, PPG, and CIRIA guidance
End-to-End Service
Complete coordination delivering cost-effective solutions
750+ Projects
Proven track record across all development scales
94% Success Rate
Near-perfect approval rate at first submission
Frequently Asked
Questions
What is a Flood Risk Assessment (FRA) for planning?
An FRA demonstrates that a development is safe from all forms of flooding for its lifetime and aligns with the NPPF and PPG. It includes design levels, mitigation, resilience, and emergency-planning measures.
When do I need an FRA?
You'll need one if your site lies within Flood Zones 2 or 3, is larger than 1 ha in Flood Zone 1, or if local mapping identifies increased flood risk. Use the Flood Map for Planning service to check requirements.
What are the Sequential and Exception Tests?
The Sequential Test directs development to the areas of lowest flood probability, while the Exception Test demonstrates that the proposal will be safe, sustainable, and beneficial to the community.
How do climate-change allowances affect design?
The EA's latest allowances for river flows, rainfall intensity, and sea-level rise determine design event thresholds (e.g. 1% AEP + climate change). The chosen allowance depends on vulnerability class and development lifetime.
How is safe access and egress assessed?
We use the Defra/EA hazard-to-people method (depth × velocity + debris factor) to determine safe access routes and emergency thresholds.
What EA data do you request for an FRA?
We obtain detailed model outputs (historically "Product 4"), defence/asset data (via AIMS Spatial Flood Defences, formerly "Product 8"), and all relevant Flood Map for Planning and RoFRS layers.