23 Flood risk and water management

FW 1

Flood risk and water management

Flood risk

• Where relevant all development must consider its vulnerability to flooding, taking account of all sources of flood risk and the impacts of climate change. 
• Apply a borough wide Sequential Test where required in line with the National Planning Policy Framework (NPPF) and the Planning Practice Guidance (PPG). Proposals for development must seek to utilise land at lowest risk of flooding from all sources. 
• In the application of the sequential test the search for alternative sites should be borough-wide and should not be restricted to sites only capable of accommodating the proposed scale of development. Opportunities to provide development on more than one, sequentially preferable site should be explored where suitable. More guidance on the application of the sequential test is anticipated in future updates to the Flood Risk and Coastal Change PPG. 
• Where development is necessary in areas of greater flood risk, the development should be made safe for its lifetime without increasing flood risk elsewhere. 
• Where required, the Exception Test will also be applicable in line with the NPPF and the PPG. Flood resilient construction should be utilised to manage any residual risk. 
• For development proposals where only part of the site is affected by flooding, including any future flood risk, a sequential approach should be applied to the layout of development avoiding vulnerable uses and site accesses being located in areas at higher risk. If this is achieved, a sequential test may not be necessary and will be subject to case by case assessment. 
• The assessment of flood risk in relation to any proposed development, should take into account the Cheshire West and Chester Strategic Flood Risk Assessment (SFRA) update (in preparation at the time of writing) and its mapping in addition to the updated mapping provided nationally through the national flood risk assessment (NaFRA2) (Environment Agency). 

Flood Risk Assessment

• The policy will set out the requirements for a site-specific flood risk assessment in line with NPPF and PPG. 

Sustainable Drainage

The policy will detail the standards and requirements to manage surface water drainage effectively and reduce the risk of flooding elsewhere including:

• how surface water runoff should be appropriately managed (in accordance with the Cheshire West and Chester Sustainable Drainage Systems (SuDS) Guidance or any subsequent replacement standards;
• how development proposals should manage and discharge surface water through a sustainable drainage system (SuDS). The preference will be for new development to incorporate surface level SuDS with multi-functional benefits, as opposed to underground tanked storage systems, for the management of surface water;
• the requirement for approved development proposals to be supplemented by appropriate maintenance and management regimes for surface water drainage schemes;
• that development proposals should not result in the loss of open watercourse, and culverts should be opened wherever possible;
• the use of SuDS to enhance the site design and sense of place and where it is incorporated in open space, provide a safe naturalised system without the need for fencing or barriers in line with the Design Code. 

Flood Storage

• The outputs from the SFRA update will be used to identify the need for additional flood storage areas in liaison with the LLFA and EA. 

Natural flood management

The policy will detail the standards and requirements to deliver natural flood management solutions in accordance with the Local Nature Recovery Strategy (LNRS) including:

• the design and layout of the SuDS to prioritise nature-based solutions and be designed to incorporate surface water management features as green and blue infrastructure wherever possible; maximising multifunctional benefits for biodiversity, amenity, cooling and water quality;
• the requirement for natural flood management features such as SuDS to be incorporated into design of schemes providing amenity value and / or biodiversity improvements;  
• the requirement for watercourses and riverside habitats to be conserved and enhanced, where necessary through management and mitigation measures.

Water quality, supply and treatment

• The current policy requirements to ensure that development proposals do not cause unacceptable deterioration to water quality or have an unacceptable impact on water quantity (including drinking water supplies, water for industry and managing drought) or wastewater infrastructure capacity will be retained.