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New National Standards for Sustainable Drainage

On 19th June DEFRA published the new ‘National Standards for Sustainable Drainage (SuDS)’. These standards are intended to be used in the design of surface water drainage systems for new infrastructure and development, whether on greenfield or brownfield sites.

These standards replace the ‘Non-Statutory Guidance for SuDS’ and immediately became a material planning consideration.

The LLFA is currently in discussion the Local Planning Authorities to ensure a coordinated and consistent approach to planning responses can be provided across East Sussex.

Further information will be provided here in due course.

Alternatively, if you have a specific query regarding this new guidance, please contact the Flood Risk Management team at FRM@eastsussex.gov.uk.

East Sussex County Council (as the Lead Local Flood Authority or LLFA) provides a strategic flood risk role across East Sussex. As part of this role, we are a statutory planning consultee in relation to flood risk and rainwater/ surface water drainage for major planning applications across the county.

Our advice to the Local Planning Authorities (LPAs) is considered alongside other consultation responses and planning matters during the determination process. Planning decisions are the sole responsibility of the relevant LPA and the LLFA does not have the power to alter a planning decision.

Seeking advice before submitting a planning application

Flood risk management and drainage design can have a significant impact on a development’s masterplan and for that reason we recommend developers engage with us prior to submitting a major planning application.

Pre-application advice from the LLFA is separate to any pre-application service provided by Local Planning Authorities or other ESCC teams. Any fees will be payable directly to the LLFA.

Apply for formal planning advice. [140.1 KB] [docx]

Pre-application guidance and advice

Service	Fee	Request
ESCC framework for integrating sustainable drainage into developments.	Free	Available to download: Guide to Sustainable Drainage in East Sussex [7.4 MB] [pdf] Water. People. Places. A guide for master planning sustainable drainage into developments [6.0 MB] [pdf]
County level guidance for major planning applications.	Free	Available online here: General advice for major applications.
County level guidance for minor planning applications.	Free	Available online here: General advice for minor applications
Information regarding any assets which may have an impact on the management of local flood risk (and are not the responsibility of the Highway Authority, Environment Agency or a Water and Sewerage Company).	Free	Please email FRM@eastsussex.gov.uk with a location plan, street address and either a what3words reference or grid reference for the site.
Advice meeting Review of a maximum 5 pages on information prior to a meeting to be undertaken by a suitably qualified officer on behalf of the Flood Risk Management team Maximum 1-hour virtual meeting/phone call with the reviewing officer. A short email outlining the officer's views and comments on the information, submitted post meeting. VAT receipt on payment. Can be utilised on its own or alongside written advice services listed below. Not suitable for technical reviews of full detailed drainage designs, flood modelling, or flood management designs without additional advice provided.	£495 + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Written advice - 5 page limit Review of maximum 5 pages of information undertaken by a suitably qualified officer on behalf of the Flood Risk Management team. A short email outlining the officer's views and comments on the information submitted. VAT receipt on payment. Not suitable for technical reviews of full detailed drainage designs, flood modelling, or flood management designs.	£340 + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Written advice - unlimited pages Review of unlimited pages of information submitted undertaken by a suitably qualified officer on behalf of the Flood Risk Management team. An email outlining the officer's views and comments on the information submitted.	Price on request Based on estimated time for review at a rate of £155/hr + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Fully bespoke advice service If the above services do not address your requirements, please provide a detailed description of the advice/service you require to to allow a bespoke quote to be provided.	Price on request	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk

By submitting a request for pre-application advice, you consent to East Sussex County Council holding and processing your data. For more information, please see our privacy notice.

Seeking advice after submitting a planning application (post-app)

As a statutory consultee the LLFA will provide a substantive response to consultations on major developments received from the Local Planning Authorities. If following receipt of our comments an applicant requires further advice we provide the below detailed services.

Apply for formal planning advice. [140.1 KB] [docx]

Post-application guidance and advice

Service	Fee	Request
ESCC framework for integrating sustainable drainage into developments.	Free	Available to download: Guide to Sustainable Drainage in East Sussex [7.4 MB] [pdf] Water. People. Places. A guide for master planning sustainable drainage into developments [6.0 MB] [pdf]
County level guidance for major planning applications.	Free	Available online here: General advice for major applications.
County level guidance for minor planning applications.	Free	Available online here: General advice for minor applications
Information regarding any assets which may have an impact on the management of local flood risk (and are not the responsibility of the Highway Authority, Environment Agency or a Water and Sewerage Company).	Free	Please email FRM@eastsussex.gov.uk with a location plan, street address and either a what3words reference or grid reference for the site.
Advice meeting Review of a maximum 5 pages on information prior to a meeting to be undertaken by a suitably qualified officer on behalf of the Flood Risk Management team Maximum 1-hour virtual meeting/phone call with the reviewing officer. A short email outlining the officer's views and comments on the information, submitted post meeting. VAT receipt on payment. Can be utilised on its own or alongside written advice services listed below. Not suitable for technical reviews of full detailed drainage designs, flood modelling, or flood management designs without additional advice provided.	£495 + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Written advice - 5 page limit Review of maximum 5 pages of information undertaken by a suitably qualified officer on behalf of the Flood Risk Management team. A short email outlining the officer's views and comments on the information submitted. VAT receipt on payment. Not suitable for technical reviews of full detailed drainage designs, flood modelling, or flood management designs.	£340 + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Written advice - unlimited pages Review of unlimited pages of information submitted undertaken by a suitably qualified officer on behalf of the Flood Risk Management team. An email outlining the officer's views and comments on the information submitted.	Price on request Based on estimated time for review at a rate of £155/hr + VAT	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk
Fully bespoke advice service If the above services do not address your requirements, please provide a detailed description of the advice/service you require to to allow a bespoke quote to be provided.	Price on request	Please email a completed request for formal advice form (found at the top of this page) to: Su.DS@eastsussex.gov.uk

General advice for major applications

National planning policy requires all developments to not increase flood risk elsewhere and remain safe from flooding for the lifetime of the development. In addition, all major developments must utilise sustainable drainage systems (SuDS) to manage surface water drainage.

The level of detail required to be submitted differs depending on site and development characteristics, as well as planning application type. This section outlines the minimum information ESCC expects applicants to submit to allow a substantive consultation response to be provided to the Local Planning Authority based on application type. Where further details are required due to site and development characteristics this will be highlighted as part of our consultation response (or during a pre-application advice consultation).

All drainage strategies and designs should follow national policy and guidance, available to view online at:

Outline application requirements

Application details

Application number.
Site address.
Site co-ordinates and/or What3Words reference.
Site are in hectares.
Existing site usage.
Proposed development.
Existing site plan.
Proposed development plan/masterplan.

Flood Risk

Sufficient information should be submitted which shows, in principle, that the development will be safe from flooding for its lifetime and will not increase flood risk elsewhere. This should include as a minimum:

A plan showing the flood zones of the site.
A plan showing the surface water risk of the site.
A Flood Risk Assessment which meets the requirements of the Environment Agency and DEFRA as set out in their online guidance: Flood risk assessments: applying for planning permission - GOV.UK.
Outline information into how safe access during the design flood and emergency egress during the extreme flood could be achieved as part of the development.

We advise applicants that flood risk from all sources of flooding should be treated consistently, and no single source of flooding should be considered more important than another. In line with national guidance flood risk assessments should consider the design flood event from all sources as well as greater frequency flood events, especially the 1:30 flood event.

In areas of increased flood risk the level of detail required, even at outline application stage, is likely to be significant and may require site specific flood modelling.

It is advised that developers engage in pre-application discussions with the LLFA if their development incorporates more or highly vulnerable development and/or the site is subject to increased flood risk from any source.

Drainage

At outline application stage applicants should be able to provide evidence that, in principle, surface water drainage will be possible for the type and scale of development proposed.

We advise that infiltration drainage is generally difficult to achieve due to the poor infiltration potential of much of our geology and high groundwater levels found across the county.

As a minimum we would expect the following information/plans to be presented as part of an outline drainage strategy:

Topographic survey.
Details of existing drainage of the site (man-made and natural).
Existing and greenfield runoff rates and volumes.
Outline proposed runoff rates and volumes (based on impermeable/hard landscape areas of submitted masterplan layout).
A plan showing the proposed outline drainage strategy, including proposed attenuation areas and discharge points.
An outline drainage strategy report which demonstrates compliance with the national Planning Practice Guidance, the non-statutory technical standards and any relevant Local Planning Authority drainage policies.
If infiltration drainage is proposed, then evidence that winter groundwater levels and infiltration potential of the site have been investigated and considered will be required.

Full application requirements

Application details

Application number.
Site address.
Site co-ordinates and/or What3Words reference.
Site area in hectares.
Existing site usage.
Proposed development.
Existing site plan.
Proposed development plan/masterplan.

Flood Risk

A plan showing the flood zones of the site.
A plan showing the surface water risk of the site.
A Flood Risk Assessment which meets the requirements of the Environment Agency and DEFRA as set out in their online guidance: Flood risk assessments: applying for planning permission - GOV.UK.
Outline information into how safe access during the design flood and emergency egress during the extreme flood could be achieved as part of the development.

In areas of increased flood risk the level of detail required is likely to be significant. If any development, including level changes, are proposed within the flood extents then site specific flood modelling is likely to be required. We advise applicants to engage in pre-application discussions with the LLFA to ensure any modelling undertaken meets requirements.

It is also advised that applicants engage in pre-application discussions with the LLFA if their development incorporates more or highly vulnerable development and/or the site is subject to increased flood risk from any source, and this has not been undertaken at an earlier planning stage.

Drainage

At full application stage we expect applicants to submit a largely complete drainage design which shows how the proposed development shall manage surface water drainage in line with national and local drainage guidance and policies.
We advise that infiltration drainage is generally difficult to achieve due to the poor soakage potential of much of our geology and high groundwater levels found across the county. Any proposed use of infiltration drainage will therefore need to be fully evidenced with winter groundwater level monitoring results and infiltration testing.
As a minimum we would expect the following information/ plans to be presented as part of a drainage design:

Topographic survey.
Details of existing drainage of site (man-made and natural).
Details of site and ground conditions including contamination and geo-hazard (such as ground stability).
- Groundwater monitoring and infiltration testing (to BRE365 standard) will be required, unless it can be shown that these are not required. We would advise that due to generally high groundwater across the county, winter groundwater monitoring will be required for most sites regardless of drainage design to ensure excavations consider potential groundwater ingress.
Existing and greenfield runoff rates and volumes.
Proposed runoff rates and volumes (based on finalised development layouts and landscaping plans).
Plans showing the proposed drainage system, including component details such as pipe diameters and ground and invert levels.
Drainage calculations, with drainage features identifiable on both calculations and plans.
A drainage design report which demonstrates compliance with the national Planning Practice Guidance, the non-statutory technical standards and any relevant Local Planning Authority drainage policies.
Outline information into how surface water exceedance flows shall be managed to ensure no internal flooding occurs on site, and flood risk is not increased offsite.
An initial assessment of offsite flood risk impacts, demonstrating how they shall be managed to ensure development does not increase flood risk elsewhere.
Drainage system outfall/connection information including locations and agreements in principle from all relevant authorities/asset owners.
- Should access to third party land be required to facilitate connection then evidence of an agreement in principle for this will also be required.
Evidence that consideration has been given to maintenance and management of the proposed drainage system considering the proposed development and other services on site. This should include as a minimum:
- Plans showing the proposed development and the easement/maintenance corridors for all onsite services (retained, existing and proposed).
- Outline information into the proposed means of maintaining each drainage element including potential responsible parties (i.e. adoption by water authority, private maintenance and management company etc.).

Discharge of conditions application requirements

Flood Risk

It is unusual to manage any flood risk elements of a development via a planning condition. Any flood risk condition placed on a planning permission will therefore have bespoke requirements.

We advise applicants to engage with us via the pre-application process to ensure all relevant information is provided to address the needs of the condition.

Drainage

At discharge of conditions stage a complete, for construction, detailed drainage design should be submitted by the applicant, and should include:

Topographic survey (existing) and proposed level plan.
Details of existing drainage of site (man-made and natural).
Details of site and ground conditions including contamination and geo-hazard (such as ground stability).
- Groundwater monitoring and infiltration testing (to BRE365 standard) will be required, unless it can be shown that these are not required. We would advise that due to generally high groundwater across the county, winter groundwater monitoring will be required for most sites regardless of drainage design to ensure excavations consider potential groundwater ingress.
Existing and greenfield runoff rates and volumes.
Proposed runoff rates and volumes (based on finalised development layouts and landscaping plans).
Plans showing the proposed drainage system, including component details such as pipe diameters and ground and invert levels.
Long and cross sections of the proposed drainage system, showing finished levels, cover levels, invert levels, gradients, and referenced drainage features.
Drainage calculations, with drainage features identifiable on both calculations and plans.
- Details of all assumptions, design criteria and emptying times should also be included.
A drainage design report which demonstrates compliance with the national Planning Practice Guidance, the non-statutory technical standards and any relevant Local Planning Authority drainage policies.
Details into how surface water exceedance flows shall be managed to ensure no internal flooding occurs on site, and flood risk is not increased offsite. As a minimum this should include:
- Evidence all of watercourses/ditches and surface water flow routes on site have been maintained post-development.
- Plans showing proposed surface water exceedance flow routes and any areas where exceedance flood waters are designed to be stored.
- A plan showing the pre and post development surface water flow routes across the site to ensure flood risk offsite is not increased.
An assessment of offsite flood risk impacts, demonstrating how they shall be managed to ensure development does not increase flood risk elsewhere.
Drainage system outfall/connection information including locations and agreements in principle from all relevant authorities/asset owners.
- Should access to third party land be required to facilitate connection then evidence of an agreement in principle for this will also be required.
Design specific construction details for all drainage elements, including storage and flow controls.
A maintenance and management plan for the proposed development which should include:
- Evidence that consideration has been given to maintenance and management of the proposed drainage system considering the proposed development and other services on site.
- Plans showing the proposed development and the easement/maintenance corridors for all onsite services (retained, existing and proposed).
- Details of the proposed means of maintaining each drainage element including responsible parties (i.e. adoption by water authority, private maintenance and management company etc.).

General advice for minor applications

The LLFA has no statutory responsibility to provide planning consultation responses to Local Planning Authorities for non-major or minor planning applications. However, applicants should be aware that national planning policy continues to apply to minor applications and as such flood risk and drainage remain requirements of this scale of planning application.

On a case-by-case basis the LPAs may request flood risk and drainage assistance from the LLFA for non-major and minor planning applications. Where we feel our assistance could be useful, we will provide non-statutory advice to the LPA to assist their planning decision. The LLFA no longer provides formal recommendations or potential condition wording for non-major or minor planning applications.

Flood Risk

The Environment Agency has produced guidance on when flood risk assessments should be undertaken and what information those assessments should contain.

General guidance on when an assessment is needed, and what it should include is available online at https://www.gov.uk/guidance/flood-risk-assessment-for-planning-applications.

Standing advice for both minor extensions and minor applications is also available online at: https://www.gov.uk/guidance/flood-risk-assessment-standing-advice.

The Environment Agency’s advice is focused on flood zone flood risk (main rivers and the sea). We advise applicants to contact their LPA to determine whether there are any local standing advice/ policies relating to other flood risk sources, such as surface water.

Drainage

ESCC understands applicants and the LPAs may require support with regards to determining what sustainable drainage is suitable for small scale development. We have therefore created a free to use online tool which allows applicants to undertaken high-level drainage calculations considering mapped ground conditions. This tool provides users with an estimate on required storage volumes and potentially viable sustainable drainage elements which can be used to create a drainage strategy for a site.

SuDS Decision Support Tool for Small Scale Development.

Our policy on deep-bored soakaways

In line with advice received from the Environment Agency, ESCC generally oppose the use of deep-bored soakaways as a means of managing surface water drainage on developments. The reasoning for this opposition is two-fold.

The increased risk of groundwater contamination due to direct discharge of waters into groundwater.
The potential impact on local groundwater levels and flows which can increase the likelihood of groundwater reaching the surface (and potentially increasing flood risk).

ESCC recommend that deep-bored soakaways are used as a last resort where the ground conditions are suitable, and the groundwater levels are known. The County Council requires that the following criteria are met when deep bored soakaways are proposed:

Investigations showing there are no other alternative surface water destinations.
The depth of the system should be no deeper than what is required for soakage.
A minimum of two water treatment stages using SuDS measures must be provided upstream of the soakaway.
An unsaturated zone must be provided below the base of the structure. There should be a minimum of 10m between the base of the structure and recorded maximum winter groundwater level.

Our policy on development near watercourses

The Lead Local Flood Authority requires a minimum 5m no development buffer from the top of bank, or edge of culvert for all ordinary watercourses. This buffer is required to maintain access to the watercourse for ongoing maintenance and management of the watercourse.

Should a 5m buffer be considered unrealistic by a developer we advise that this is raised as part of pre-application conversations.

Where other policies or guidance require a no development buffer from a watercourse, we advise that the maximum buffer distance should be utilised.

Comments from Third Parties on Flood Risk Matters Relating to Planning Applications

We are aware that development proposals, particularly those of a significant size, can often give rise to flood risk and drainage related concerns from members of the public and community groups and organisations. Should you have such concerns then you will need to put these to the relevant Planning Authority during the consultation stage of the planning application. It may be the case that the County Council, as the LLFA, provides comments on such applications that differ from your own views. In this regard, it is important to note that the County Council has to consider and appraise the development proposal in an objective manner, having regard to robust evidence and relevant planning policies, which includes the Government’s National Planning Policy Framework.

With the above in mind, should an individual or organisation wish to challenge the advice we have provided on a planning application then they will need to do so through the relevant Planning Authority. It will then be for the planning authority to decide whether they wish to seek further clarity or advice or reconsideration of position from the County Council. Ultimately it needs to be the planning authority who are content with the advice we are providing as they will be making the decision on the application in question.

It is recognised that very occasionally, a third party (i.e. member of public, town or parish council, etc.) may identify a factual error in either the flood risk evidence that supports the application and or our response to the application. Should this be the case then please contact the County Council highlighting what this factual error is. In turn, we will review our representation, amend it where necessary and maintain a close dialogue with the relevant planning authority and applicant, if necessary. We will respond to the individual or organisation that have highlighted the error to explain what course of action we have taken.

Any correspondence we receive that expresses concerns over flood risk matters, within the context of a planning application, will be sent to the relevant planning authority for their consideration in the determination of the application. In such cases we will acknowledge the correspondence and explain who we have passed it onto and how it will be considered. If you have concerns over sharing of the correspondence between the Local Authorities, please take a look at our privacy notice.

Our policy on groundwater monitoring

In line with best practice and national guidance, ESCC require groundwater monitoring results to be provided as part of drainage design submissions.

The County Council can provide the following guidance on our requirements for groundwater monitoring:

Groundwater monitoring should be undertaken over a 6-month winter period
- Our preferred monitoring period is October - March, although November - April is also considered acceptable.
Groundwater monitoring locations should consider potential drainage locations and any below ground development such as basements.

We would also advise that any designs based on the groundwater monitoring should also utilise published or publicly available groundwater data, including the BGS depth to groundwater dataset. This is to help ensure that wider impacts on groundwater conditions, such as extended dry periods, are considered within designs.