Local Flood Risk Management Strategy

Our objective is to support the development of places that are more climate resilient.

As a result, new developments will be at lower risk of flooding from all sources and will include sustainable drainage and blue-green infrastructure, bringing multiple benefits. Existing properties and infrastructure will ‘build back better’ to become more resilient to future flooding. The actions we will be undertaking to address this objective are set out in our action plan.

Effective, adaptive land use planning is paramount in facilitating sustainable development to minimise flood risk. New development has the potential to increase flood risk, yet also has the potential opportunity for managing current and future flood risk through innovative design.

The National Planning Policy Framework (NPPF) (2021) and Planning Practice Guidance (PPG) (2022) have been updated since the previous strategy was published.

Buckinghamshire Council is currently preparing a Local Plan (LP4B) which will set out our vision and objectives as a unitary authority for new developments from 2027 up to 2040. We will provide technical advice helping to sequentially plan and steer development away from flood risk from all sources, now and in the future (as required by Paragraph 162 of the NPPF).

We will support the development of the Strategic Flood Risk Assessment and Water Cycle Study for the Local Plan for Buckinghamshire. We will also advise our Local Planning Authority colleagues of opportunities to manage existing and future flood risk through development.

There are notable gaps in the consideration of groundwater flood risk in national planning policy and climate change guidance, in comparison to other sources of flooding. Project Groundwater is trying to tackle this problem through its Placemaking workstream, and it is our ambition that the outcomes will influence and strengthen groundwater flood risk planning policy nationally.

Sustainable drainage systems (SuDS) aim to reduce the impact of development by replicating the natural processes through which rainwater is captured, stored, and transported. SuDS can be integrated as part of blue-green infrastructure provision in new developments and regeneration projects.

As well as managing surface water runoff, well designed SuDS have many other benefits which improve our climate and biodiversity resilience. They can provide some natural removal of pollutants and sediments, promote aquifer recharge and enhance biodiversity. SuDS should be designed to also add aesthetic value and offer attractive natural amenity for the local community.

These benefits can contribute to the aims of the:

• Climate change and air quality strategy
• Biodiversity Net Gain
• Biodiversity Action Plan
• Local Nature Recovery Strategy
• Vision and Principles for the improvement of Green Infrastructure
• Thames Drainage and Wastewater Management Plan
• Anglian Drainage and Wastewater Management Plan

A key part of our role in supporting the development of places that are more climate resilient is to promote and use our statutory role to ensure that well-designed SuDS delivering a range of other benefits are built in Buckinghamshire.

Water companies can adopt SuDS if they meet the industry's Design and Construction Guidance.

We are a statutory consultee in the planning process in relation to surface water drainage for major development. We also have a local arrangement in place with our Local Planning Authority colleagues to provide advice on planning applications with three dwellings or more or a non-residential footprint greater than 250m2.

We have published guidance on planning submissions in relation to surface water drainage. This guidance sets out the requirements and design standards for the management of surface water runoff and drainage for varying types of planning applications within Buckinghamshire. We require developers to demonstrate that any new development does no exacerbate existing flood risk and is designed to maintain runoff to at or below pre-development rates. You can view the SuDS guidance for developers on our website.

We will advise the Local Planning Authority on how to ensure that new development does not exacerbate existing flood risk and is resilient to climate change, by following government guidance on how to consider climate change in flood risk assessments.

Following the announcement made in January 2023 by the Department of Environment, Food and Rural Affairs (Defra) it is expected that Schedule 3 of the Flood and Water Management Act 2010 will be implemented in 2024. The enactment of Schedule 3 will have the following implications for the planning process:

• Designation of local authorities as SuDS Approval Bodies (SAB) which have a duty to adopt new drainage systems.
• The cessation of the automatic right for new developments to connect to the existing sewer system.
• Developers must ensure that drainage systems are built as per the approved drainage plan that complied with mandatory national standards as outlined in the NPPF and the PPG.

Following the implementation of Schedule 3, it is expected that new legislation will adopt relevant findings and recommendations from the Defra research project (Recommendations to Update Non-Statutory Technical Standards for Sustainable Drainage Systems) published in July 2021. We anticipate that the introduction of new statutory standards will allow for the strengthening of requirements to achieve higher quality SuDS schemes that are able to deliver many benefits.

The council will incorporate our new role as a SuDS Approval Body (SAB) within our wider functions as a local authority. Our duties as a SAB will sit in parallel with the planning application process, drainage strategies will be evaluated more extensively against requirements for amenity, biodiversity net gain, water quality and other relevant drivers beyond flood risk.

The planning process will therefore include greater engagement with others within the council (such as Ecology and Highways teams), to ensure that opportunities to maximise benefits and minimise risk are identified as early as possible.

Existing buildings and roads often have old drainage systems, which are not designed with an allowance for climate change. However, it is possible to retrofit SuDS that are able reduce existing flood risk both in the surrounding area and wider catchment, and improve climate resilience, particularly in more frequent, low magnitude events.

Retrofit schemes can also be made more cost-beneficial if they are included within a wider programme of works to regenerate an area. Possible interventions could include:

• Multifunctional green spaces e.g. attenuation or swales in parks
• Green roofs
• Rain gardens or bio-retention features upstream of existing highway gullies
• Disconnecting down pipes into plot-scale rain gardens
• Rainwater harvesting

Anglian Water and Thames Water recognise the value of retrofitting SuDS in relieving pressure on foul and combined sewer networks and reducing sewer overflows by reducing surface runoff contributions. This is particularly important for Buckinghamshire's environmentally sensitive Chalk streams.

We will work with communities, Buckinghamshire Highways, water companies and other stakeholders to identify opportunities to retrofit SuDS in our towns and villages. We will support Buckinghamshire Highways in developing a 'build back better' climate resilient approach to Highway works which includes SuDS retrofit. We will also explore the options for maintenance of retrofit schemes by suitable council contractors.

Community engagement is a vital component of delivering urban retrofit schemes. Engagement can also be productive beyond gaining support for schemes, particularly where tangible benefits for the wider community can be demonstrated and opportunities for the long-term implementation, maintenance and ownership by the community can be explored.