Draft Flood Risk Supplementary Planning Document

Part 2 Development and flood risk

2.1 Flood risk and the planning process

2.1.1 A site-specific FRA is carried out to assess flood risk to and from a development and should accompany a planning application, where appropriate.

Is an FRA required?

2.1.2 Before proceeding all applicants are advised to use the flow chart (Figure 3) and information below to determine if an FRA is required. This applies to all development including minor[1] but excluding proposals where there will be no impact on flood risk e.g. loft conversions and first floor extensions above an existing ground floor extension where there is no change of use and non-ground based adverts.

Figure 3: Determining whether an FRA is required

Figure 3 - Determining whether an FRA is required

2.1.3 In order to determine if an FRA is required applicants must have an understanding of the sources of flood risk that affect a site (Tables 5 and 6).

2.1.4 Whilst the main source of flood risk in Elmbridge is from rivers (Table 5) it is also important to consider other sources of flooding e.g. groundwater, surface water etc. (Table 6).

Table 5 - Flood risk from rivers

Sources of flooding

When is an FRA required

Where to look

Flooding from Rivers

Is the site located within Flood Zones 2 or 3?

Is site located within Flood Zone 1 and over 1ha?

SFRA Appendix C & E

Table 6 - Flood risk from other sources

Sources of flooding

When is an FRA required

Where to look

Flooding from Land

Is the site affected by surface water flooding e.g. within at High (1 in 30 year) or Medium/Low (1 in 100 year)? and;

Has the site been affected by flooding in the past.

SFRA Appendix D & E

Flooding from Groundwater

Is there potential for groundwater flooding to occur at the surface or to affect properties below ground?

Has the site been affected by flooding in the past?

SFRA Appendix B, Figures B2, B3, B5.& Appendix

Flooding from Sewers

Has the site been affected by flooding in the past?

SFRA Appendix E, Appendix B, Figures B7 & B8

Reservoirs, canals and other artificial sources

Is the site at risk of flooding from reservoirs?

SFRA Appendix E

Risk of Flooding from Reservoirs mapping (EA website)[2] .

2.1.5 Once the sources of flooding have been considered it is necessary to determine the vulnerability classification of the development. FRAs are required where a change of use to a more vulnerable class is proposed and the site is affected by other sources of flood risk. The Government has produced a list of vulnerability classifications and these are reproduced in Appendix 1[3] .

1. Minor development – minor non-residential extensions: industrial/commercial/leisure etc extensions with a footprint of 250 sqm or less; alterations: development that does not increase the size of buildings e.g. alterations to external appearance; householder development: for example; sheds, garages, games rooms etc. within the curtilage of the existing dwelling, in addition to physical extensions to the dwelling itself. This definition excludes any proposed development that would create a separate dwelling within the curtilage of the existing dwelling e.g. subdivision of house into flats [back]
2. Risk of Flooding from Reservoirs - http://watermaps.environment-agency.gov.uk/wiyby/wiyby.aspx?topic=reservoir&scale=1&textonly=off&ep=map&layerGroups=default&lang=_e&y=355134&x=357683#x=357683&y=355134&scale=1 [back]
3. An FRA may also be required where a site is located within Flood Zone 1 but is surrounded by flooding (‘dry island’). [back]

Is development appropriate?

2.1.6 Where a site is affected by flooding from rivers there are strict controls on the types of development that are appropriate within different Flood Zones depending on the vulnerability classification (Appendix 1). Prior to preparing an FRA applicants are encouraged to consider whether or not the proposed development is likely to be appropriate in the proposed location (Table 7).

2.1.7 If the development type is not appropriate it is unlikely that it would be permitted and, therefore, applicants should consider carefully whether or not to proceed with an application.

2.1.8 If development is appropriate then applicants should proceed to prepare an FRA to accompany their planning application. The remaining sections of this SPD provides detailed guidance on the preparation of an FRA.

Table 7: Development types and appropriate uses

Flood Zone 3b (1 in 20 (5%) annual probability flood outline)

Undeveloped land (Functional Floodplain), where water has to flow or be stored in times of flood, should be protected from any new development. Only Essential Infrastructure or Water Compatible development may be permitted. Basements are not not permitted.

Flood Zone 3b (1 in 20 (5%) annual probability flood outline)

Developed land relates solely to existing buildings that are impermeable to flood water. Some minor or re-development proposals may be considered[4] . Changes of use to a higher vulnerability classification are not permitted. Basements, basement extensions, conversions of basements to a higher vulnerability classification or self-contained units are not permitted.

Flood Zone 3a (High Probability)

Land use should be restricted to Water Compatible or Less Vulnerable development. More Vulnerable development can be considered. Highly Vulnerable development is not appropriate. Self-contained residential basements and bedrooms at basement level are not permitted. All other basements, basement extensions and basement conversions may be considered. Regard will be had to whether the site is also affected by groundwater flooding.

Flood Zone 2 (Medium Probability)

Land use should be restricted to Water Compatible, Less Vulnerable or More Vulnerable development. Highly Vulnerable development can be considered. Self-contained residential basements and bedrooms at basement level are not permitted. All other basements, basement extensions and basement conversions may be considered. Regard will be had to whether the site is also affected by groundwater flooding.

Flood Zone 1 (Low Probability)

No restrictions

NB - Areas shown to be affected by climate change will be treated as 3a and areas in Flood Zone 1 surrounded by flood water ('dry islands') will need to have regard to the Flood Zone surrounding the site and may require an FRA.

4. See Appendix 3 for details of approach [back]

Why are FRAs required?

2.1.9 FRAs are required to provide an assessment of flood risk and demonstrate how the proposed development will be made safe, will not increase flood risk elsewhere and where possible will reduce flood risk overall. The objectives of an assessment are to establish:

  • whether it is likely to be affected by current or future flooding from any source;
  • what measures are proposed to deal with these effects and risks are appropriate;
  • evidence to show that the development does not increase the risk of flooding elsewhere by not impeding flow or reducing flood storage capacity;
  • whether development is safe for its lifetime and passes the Exception Test, if applicable; and
  • the evidence for the local planning authority to apply (if necessary) the Sequential Test.

What needs to be addressed in an FRA?

2.1.10 The requirements for a FRA will vary depending on the degree and type of flood risk, scale and nature of development, its vulnerability classification and whether or not the Sequential or Exceptions Tests are required (See Section 2.4). For example, where the development is an extension to an existing house in a lower risk area, the Council would generally require a less detailed assessment in order to make an informed decision.

2.1.11 Site specific FRAs should make full use of readily available information in the first instance, for example the mapping within the SFRA, although in some cases additional modelling, detailed calculations or site surveys will need to be undertaken. 

Enough information must be included to enable the Council to determine that the development is safe, does not increase flood risk elsewhere and, where possible, reduces risk overall. If sufficient information is not provided this could result in the application being refused.

How to submit a valid planning application?

2.1.12 Where an FRA is required, this must be submitted alongside a planning application. All FRAs must include a completed FRA pro-forma using the template table included in Appendix 2. This should be included at the front of the assessment to summarise and signpost findings or for low risk applications it may form the actual FRA.

2.1.13 Regardless of whether a FRA is required, all major[5] planning applications must submit a separate Surface Water Drainage Pro-forma[6] . Where appropriate this should be cross referenced within the FRA. For other applications where an FRA is required surface water drainage requirements must be addressed within the accompanying FRA and for those where an FRA is not required this should be addressed within the Climate Neutral Checklist.

2.1.14 Without this information an application will not be validated. 

Where an FRA is required this must be submitted alongside a planning application accompanied by a completed FRA Proforma. For major applications a Surface Water Drainage Proforma also needs to be submitted. Without this information an application will not be validated.
5. Major planning applications – http://www.legislation.gov.uk/uksi/2010/2184/made [back]
6. Surface Water Drainage Proforma - http://new.surreycc.gov.uk/people-and-community/emergency-planning-and-community-safety/flooding-advice/more-about-flooding/suds-planning-advice [back]

Will any other formal consents be required?

2.1.15 Any works within 20 metres of a Main River or 8 metres of an Ordinary Watercourse require Flood Defence consent from the Environment Agency or Surrey County Council (as the Lead Local Flood Authority) respectively. As the requirements of the consenting process may result in changes to development proposals or construction methods, the Council will aim to consult the relevant organisations and advise on this as part of the planning process. Consents will be refused if the works results in an increase in flood risk, a prevention of operational access to the watercourse and/or an unacceptable risk to nature conservation.

Who will the Council consult with?

2.1.16 Depending on the type of application the Council will consult with different organisations as part of the planning application process.

2.1.17 The Environment Agency is consulted in the following instances:

  • Flood Zone 3 - all applications (excluding minor development) including change of use where flood risk vulnerability has changed to more vulnerable or highly vulnerable or from water compatible to less vulnerable
  • Flood Zone 2 - all applications (excluding minor development) where the flood risk vulnerability is essential infrastructure; highly vulnerable; more vulnerable (where it is a landfill or waste facility or is a caravan site); less vulnerable (where it is land or building used for agriculture or forestry; a waste treatment facility; a mineral processing site, a waste water treatment plant)
  • Flood defence consent - any development (including minor) if it is within 20m of a Main River

2.1.18 Surrey County Council (as the Lead Local Flood Authority) is consulted in the following instances:

  • Flood defence consent - any development (including minor) within 8m of an Ordinary Watercourse
  • Surface Water Management requirements - all major planning applications

How to obtain pre-application advice?

2.1.19 The Council, Environment Agency and Surrey County Council all offer pre-application advice services (Table 8) which will assist applicants in scoping the requirements of an FRA. Where to go for advice will depend on the specific issues for the particular development in question and who is consulted as part of the planning process. The Council strongly advises applicants to use these services.

Table 8 Pre-application advice services

Strategy/Guidance document

Type of advice

How to obtain advice

Elmbridge Borough Council - Pre-application advice

[Charge]

Advice on potential sources of flood risk and content of an FRA

Different levels of service offered - Platinum, Gold, Silver, Bronze.

http://www.elmbridge.gov.uk/planning/enquiryservice.htm

Elmbridge Borough Council - Duty Planning Officer

[No charge]

- Provide general

  advice

- Help identify

  planning 

  constraints

- Guidance on how

  to make an

  application

Operates between 10.00am to 1.00pm Monday-Friday via phone or face-to-face http://www.elmbridge.gov.uk/planning/advice.htm [01372 474474]

Elmbridge Borough Council - Planning Policy

[No charge]

General advice on flooding policies.

Operates between 9.00am to 5pm Monday-Friday via phone or face-to-face.[01372 474474]

Surrey County Council

[Charge]

Advice only on surface water requirements for major applications.

Request for advice can be made via flooding.enquiries@surreycc.gov.uk

Environment Agency

[No charge]

Free preliminary opinion

Request for advice made via https://www.gov.uk/government/publications/pre-planning-application-enquiry-form-preliminary-opinion

Environment Agency

[Charge]

Technical feedback, to help to ensure applicants have included all of the relevant information.

Request for advice made via https://www.gov.uk/government/publications/planning-advice-environment-agency-standard-terms-and-conditions

What are the requirements where planning permission is not required?

2.1.20 There are a wide variety of applications that require prior approval. The Council will consider these and the flood risk implications on a case by case basis.

2.1.21 Flood Defence consent may also be required for development requiring prior approval or permitted development (including minor development) and should be obtained as follows (Table 9). 

Table 9 - Flood Defence consent

When to obtain consent

How to obtain consent

Within 8m of a Main River

Environment Agency - enquiries@environment-agency.gov.uk

Within 8m of an Ordinary Watercourse

Surrey County Council (as Lead Local Flood Authority) - landdrainage.consents@surreycc.gov.uk.

How does the Council make decisions?

2.1.22 Whilst the Environment Agency and Lead Local Flood Authority are consulted for flood risk advice on higher risk and larger proposals, all decisions on planning applications rest with the Council. In all respects, this SPD and guidance within the SFRA should be used to prepare FRAs. This will help to ensure that local policy and issues have been addressed and that sufficient information is included in order for the Council to make a decision and, where appropriate, consultees to provide advice.

2.1.23 Whether or not an application has addressed the detailed requirements for the content of an FRA/ Surface Water Drainage Pro-forma will be considered by the Case Officer and relevant consultees when assessing the application. Where sufficient information has not been provided this could result in the application being refused.

Who should prepare an FRA?

2.1.24 An FRA and any accompanying Surface Water Drainage Pro-forma should be prepared by a suitably qualified person e.g. drainage engineer (recognised by the Engineering Council[7] , the Institute of Civil Engineers[8] or equivalent). This is particularly important in cases where the risk of flooding is high.

7. Engineering Council - http://www.engc.org.uk/ [back]
8. Institute of Civil Engineers - https://www.ice.org.uk/ [back]

How to prepare an FRA?

2.1.25 The following sections of this guidance provide a step-by-step guide to completing the FRA Proforma (Appendix 2) and preparing an FRA to support a planning application. It will help to ensure that it is suitable to the scale, nature and type of development proposed as well as the degree of flood risk and contains sufficient information to support decision making.