What has changed?

The short answer, is that almost everything has changed in the PPG (Planning Practice Guidance) Flood Risk and Coastal Change. From functional floodplain definition, to building lifetimes and applications of the sequential test. This is the largest overhaul of the guidance since it’s publication. It is worth noting that this change applies to England only – Wales and Scotland guidance has not been updated. So without further preamble, use the links below to jump to the section that interests you, or read through the whole lot!

Sequential Test Updates
Exception Test Updates
Design Flood Definition
Functional Flood Plain Definition
Lifetime of Development
Minor, Major and Non-Major Development Definitions
Changes of Use
Flood Mitigation
Off-Site Impacts
Safe Access & Egress
Reservoirs
Residual Risks

Aegaea will continue to monitor and update on these changes as well as explore the implication of these changes in upcoming articles and webinars.  If you would like to be included in a mailing list to find out about the webinars, please send us an email to kirsty@aegaea.com and we will mail you when dates and times are confirmed.

In the latest updates to the NPPF in July 2021, there were no changes to the wording of the Exception Test or its application. Once it has been demonstrated that the Sequential Test can be passed, it should then still be demonstrated that:

• development that has to be in a flood risk area will provide wider sustainability benefits to the community that outweigh flood risk; and
• the development will be safe for its lifetime taking account of the vulnerability of its users, without increasing flood risk elsewhere, and, where possible, will reduce flood risk overall.

Despite a move away from the EA’s Flood Zones within the Sequential Test in the PPG, the circumstances under which the Exception Test is applicable are defined by Table 2 of the PPG (previously Table 3) – which remains the same as before with only the subtle title change to ‘Flood risk vulnerability and flood zone ‘incompatibility’.

However, the updated PPG provides more in depth guidance on how both parts of the Test should be applied, which is stricter than the previous iteration (Link);

• The PPG still requires the development to demonstrate wider sustainability benefits to be provided for the first part of the test, otherwise planning permission should not be granted. It further clarifies that the impacts of flood risk on social, economic and environmental factors should be considered. One major change however that the PPG no longer states that “If a potential site allocation fails to score positively against the aims and objectives of the sustainability appraisal, or is not otherwise capable of demonstrating sustainability benefits, the local planning authority should consider whether the use of planning conditions and/or planning obligations could make it do so.”
• With respect to the second part of the Exception Test, stating that, where possible, flood risk should be reduced overall, the PPG has been updated to state “In order to demonstrate that the Exception Test has been satisfied without securing measures that would reduce flood risk overall, it will need to be demonstrated that such measures cannot be identified or are unfeasible.”

The definition of the functional floodplain is now regarded as the 3.3% AEP, or 1 in 30 year event. Previously this was defined as the 5% AEP or the 1 in 20 year event. This has major implications for proposed developments that are near watercourses or that might otherwise be defined as functional floodplain.

Despite a move to include surface water in the definition of the design flood event, the definition of the functional floodplain remains to be relevant to flood risk from rivers or the sea.

In addition, the definition no longer recognises areas which are prevented by flooding from solid buildings from being outside of the functional floodplain, although it does assume flood management infrastructure is operating as intended.

With no clear national mapping of the 1 in 30 event, this could be problematic for developers to understand the implications.  In short, it is likely that we will need to consult with the EA and LLFAs to understand the new allocation and to make sure that we offer comprehensive advice to clients. It is interesting and important to note that the guidance states that “the identification of the functional floodplain should take account of local circumstances and not be defined solely on rigid probability parameters”. So while the 1 in 30 is an approximation, local knowledge and information will still need to be taken into account.

Both the NPPF and PPG refer to requirements for ‘major development’, defined in accordance with the definition set out in The Town and Country Planning (Development Management Procedure) (England) Order 2010. This is a standard planning definition used by the Local Planning Authority, and sits alongside the definition of ‘householder development’.

Development which sites between ‘householder’ and ‘major’ development is considered as ‘minor development’ from a planning perspective. However, this is not to be confused with ‘minor development (in terms of flood risk)’ which is referenced within both the NPPF and PPG. For ‘minor development (in terms of flood risk)’ there are certain exemptions, such as the Sequential and Exception Test. Furthermore, such development falls under the EA’s Flood Risk Standing Advice, and is the responsibility of the Local Authority to assess with respect to flood risk.

In the latest PPG, certain guidance is relevant to development which is not classified as ‘major development’ and to save confusion of covering the types of application which this includes, the guidance covers this with the introduction of the simpler term of ‘non-major development’.

This iteration of the PPG adopts an updated hierarchical approach to flood risk within the guidance.  The hierarchy states that (in order of preference) flood risk to development should be reduced through:

• Avoidance of flood risk in plan making, decision making and within sites through sequential allocation.
• Control of flood risk through engagement with flood risk management authorities
• Mitigation of flood risk through use of flood resistance and resilience measures
• Management of residual flood risk through management measures and flood warnings.

The PPG emphasises that such an approach should be considered early in the design process to iron out any conflicting design requirements. A new addition to the PPG is that it explicitly states that tensions between flood risk matters and planning matters do not justify unsafe development. Examples of this include;

• The impact of raised floor levels on access. For the former, there is a focus on ensuring that design is inclusive, and encourages innovative design to mitigate flood risk whilst not excluding certain sections of society, such as the elderly or those with less mobility.
• Where historic buildings are involved, guidance states that no flood resilience for historic properties is recommended alongside early consultation with Historic England.
• Structural safety of buildings should be considered, especially for flood depths greater than 600mm where the PPG recommends that a structural engineer is consulted.

One of the largest changes to the PPG has been the focus on emergency response and safe access and egress from both new and existing development. The guidance acknowledges the challenges that may be presented to occupants/users who are less mobile or have physical impairment. It has always been a requirement to assess the availability of safe access/egress during design flood conditions, but the latest iteration of the guidance now also requires an assessment of the “ability of residents and users to….evacuate  before an extreme flood (0.1% annual probability of flooding with allowance for climate change)”. Many flood modelling studies do not include an assessment of the impact of climate change during a 0.1% annual probability event (1 in 1000 chance each year).

The guidance identities that an increase in the number of people living or working in areas of flood risk could increase the scale of evacuation required during a flood event. A significant change in the PPG is the introduction of the concept of mitigating such impact on emergency response. The guidance suggests that either design considerations within the development, or off-site works could be proposed to reduce the consequence of flooding either locally or in the wider area respectively.

Paragraph 187 of the NPPF (July 2021) is referenced with regards to the applicant (or ‘agent of change’) being required to provide suitable mitigation before the completion of development for any significant adverse effect on existing businesses or community facilities in its vicinity (including change of use). The PPG states “where the impact cannot be wholly mitigated, developers need to cover the full cost of any additional emergency services provision needed”. Details on the cost implications of this are not provided, but it is likely the provision will be made through Community Infrastructure Levy or Section 106 contributions.

Another major addition to the PPG is additional detail with respect to quantifying and mitigating ‘residual risks’ of flooding – it now has its own section!

The definition of residual risk has been extended from just the risk to a development once any site-specific flood mitigation measures are taken into account, to include the risk from flood risk management infrastructure.

Whilst the residual risks from flood risk management still include the following;

• a breach of a raised flood defence, blockage of a surface water conveyance system or failure of a pumped drainage system;
• failure of a reservoir; and
• a flood event that exceeds a flood management design standard, such as a flood that overtops a raised flood defence, or an intense rainfall event which the drainage system cannot accommodate.

The PPG now includes additional guidance on the likely presence of flood risk management infrastructure in the future. It should be considered whether flood risk infrastructure is likely to be improved to keep pace with climate change, e.g. is funding available and what are the funding options (e.g. Community Infrastructure Levy, planning obligations / S106 agreements, or Partnership Funding). This information is likely to come from the Local Planning Authority, in conjunction with Risk Management Authorities. For each circumstance, the PPG advises;

• “Where flood risk management infrastructure is likely to be improved to keep pace with climate change, the potential consequences of flooding resulting from breach or failure of that improved infrastructure is likely to be the main driver for mitigation.
• Where infrastructure is unlikely to be improved, the potential consequences of flooding resulting from overtopping or the design standard being exceeded will also be an important consideration. It is important to consider the consequences of both overtopping and breach, as the nature of flooding will be different in each case.”

Due to the potential for rapid onset of fast-flowing and deep flooding, with little to no warning of a failure, development should avoid internal flooding and ensure that people are not exposed to hazardous flooding. The latter applies irrespective of the development’s vulnerability classification. An emergency plan, or Flood Warning and Evacuation Plan, is likely to be fundamental in such circumstance to ensure users/occupants can be safe.