Tesco’s Raised Car Park: Lessons for Flood Risk Assessments and Planning Permission

Key takeaways

What happened at the flood hit Tesco site

Arun District Council has approved a raised car park scheme at a Tesco store on Shripney Road in Bognor Regis, a site with a history of flooding, despite objections from council drainage specialists. The approved design raises some car park spaces by 2m (6ft 6in), allowing customers to park there during periods of flooding.

The new deck proposed deck accommodates 191 spaces, including 22 disabled bays and 18 parent and child spaces. The scheme also includes drainage upgrades, such as a new outlet into the Aldingbourne Rife, and the planting of 36 trees.

Both West Sussex County Council’s lead flood authority and Arun District Council’s drainage engineers objected, citing concerns over flood risk, drainage standards and longterm maintenance. Planning officers concluded the scheme would improve drainage by reducing water discharge into the river, and judged that the flood resilience and access benefits outweighed the fact it did not meet all national drainage standards.

Can you get planning permission for a car park in a flood zone?

But this does not remove the need to work through the Sequential Test and, where relevant, the sequential Test.

The Sequential Test steers development to areas with the lowest flood risk. In most cases a car park is allowed in the proximity of the development if it directly related to the activities of the sites. However a sequential approach is required to locate the car park at the lowest risk of flooding.

Where the Exception Test applies, the applicant must demonstrate that the development provides wider sustainability benefits to the community that outweigh flood risk, and that it will be safe for its lifetime without increasing flood risk elsewhere. Recognised benefits include reuse of brownfield land, an overall reduction in flood risk to the wider community, and SuDS that significantly exceed policy requirements.

Development proposals should not present a risk from flooding to potential occupiers, users, or visitors, and should not increase flood risk elsewhere.

What flood risk assessment is needed for commercial development approval

A site specific flood risk assessment (FRA) is required to accompany planning applications for development in areas at risk of flooding. A flood risk assessment is required for development within Flood Zones 2 or 3, within Flood Zone 3b, or within Flood Zone 1 with a site area of 1 hectare or more.

• Model the fluvial flood risk and the design flood for surface water, defined as an event with a 1 in 100 annual probability plus an allowance for climate change
• Assess the upper end climate change allowances for both the 1% and 3.3% annual exceedance probability events for the 2070s epoch
• For major development with surface water drainage, consult the Lead Local Flood Authority
• Where the Environment Agency must be consulted under Schedule 4 of the 2015 Development Management Procedure Order, build in time for that response

Getting planning permission does not guarantee a developer will also get a flood risk permit or consent, which are often needed separately and should be scoped early.

Why raised car park design features as mitigation

Raising some car park spaces by 2m at Bognor Regis, as approved by Arun District Council, allows customers to continue parking there during periods of flooding. Raised finished floor levels should be paired with flood resistant materials and design, with any associated impact on flood risk elsewhere assessed and mitigated.

Where flood storage is lost as a result of development, on site level for level compensatory storage, accounting for climate change impacts over the development’s lifetime, should normally be provided. Stilts and voids below buildings should not normally be relied upon for this, because voids do not allow water to freely flow through them and can become blocked or silted up.

SuDS for major development need appropriate minimum operational standards and maintenance arrangements to ensure acceptable performance for the development’s lifetime. The national SuDS standards, published in June 2025, also make clear that surface water should be discharged to combined sewers only as a last resort.

Why would planners approve a scheme despite flood risk concerns

The Bognor Regis case shows how planning balance works in practice. A raised car park scheme at a Tesco store on Shripney Road was approved by Arun District Council despite objections from council drainage specialists. Both West Sussex County Council’s lead flood authority and Arun District Council’s drainage engineers objected, citing concerns over flood risk, drainage standards and longterm maintenance.

Planning officers said the scheme would improve drainage by reducing water discharge into the river and judged that flood resilience and access benefits outweighed the fact it did not meet all national drainage standards.

This does not mean objections are ignored. All local planning authorities should notify the Environment Agency of the decision on any planning application where the Agency has objected on flood risk grounds, and the Agency publishes an annual list of such cases, indicating whether its advice was followed.

What drainage standards apply to car parks in flood prone areas

Car park schemes in flood zones are judged against national SuDS standards. National standards for sustainable drainage systems were published in June 2025, providing a comprehensive seven complementary standards for the design, operation and maintenance of SuDS in new development. They make clear that surface water should be discharged to combined sewers only as a last resort, to help alleviate pressure on sewers and reduce storm sewer overflows.

For greenfield developments, the peak runoff rate to any highway drain, sewer or surface water body for the 1 in 1 year and 1 in 100 year rainfall events should never exceed the peak greenfield runoff rate for the same event. SuDS for major development also need appropriate minimum operational standards and maintenance arrangements, to ensure an acceptable standard of operation for the lifetime of the development.

The Bognor Regis scheme illustrates the attenuation and storage expectations this creates in practice.

Where flood storage is lost as a result of development, on site level for level compensatory storage, accounting for climate change impacts over the development’s lifetime, should normally be provided. Techniques such as stilts and voids below buildings should not normally be relied upon for this, because voids do not allow water to freely flow through them and can become blocked or silted up.

How are flood risk planning conditions enforced after approval

Approval of the Bognor Regis scheme was granted subject to conditions, including detailed drainage plans and measures to offset any loss of floodwater storage, before work can begin. Development carried out without having complied with a pre commencement condition would be unlawful and may be subject to enforcement action by the local planning authority.

1. Pre commencement conditions setThe decision notice lists what must be submitted and approved before any work starts, such as detailed drainage plans and compensatory storage measures.
2. Discharge of conditions applicationThe developer submits the flood risk assessment to the local planning authority, which is statutorily required to consult the Environment Agency for developments in certain flood risk areas before granting planning permission.

Carrying out development without required planning permission, or failing to comply with any condition or limitation attached to a planning permission, constitutes unauthorised development that can be subject to local planning authority enforcement action, which may require removal of buildings or works or cessation of an activity.

• Confirm which conditions are precommencement before programming any site works.
• Submit discharge of conditions applications with full technical detail to avoid delay.
• Keep records of EA and LLFA sign off for every discharged condition.

What this means for developers assessing similar sites

The Bognor Regis scheme was approved despite objections from council and lead flood authority drainage specialists over flood risk, drainage standards, and maintenance. Planning officers weighed the flood resilience and access benefits against the fact that the drainage upgrades did not meet all national standards, and approved the application subject to conditions. For developers facing similar sites, the lesson is not that standards are optional, but that evidence and early engagement determine whether an exception can be justified and conditions can be met.

Three practical points follow for any commercial scheme in a flood zone.

1. Engage early on the flood risk assessmentWhere surface water or other local flood risks are likely to significantly affect a site, early discussions with the planning authority help identify the issues the FRA must address before an application is submitted.
2. Build robust modelling evidenceAssessments should cover the design flood for surface water and the upper end climate change allowances for both the 1% and 3.3% annual exceedance probability events in the 2070s epoch, so objections can be answered with data rather than assertion.

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