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Flood risk

Technical guidance and information on the avoidance, reduction and management of flood risk.

South Gloucestershire strategic flood risk assessment (SFRA) level 1

South Gloucestershire strategic flood risk assessment (SFRA) level 2

Please note the SFRA level 2 Report errata sheet at the beginning A, B and C.

Avonmouth-Severnside strategic flood risk assessment (SFRA) level 2

In addition to referring to the SFRA, all developers and applicants should also use the most recent Environment Agency flood maps entitled “Flood Map for Planning (Rivers and Sea)”. This Environment Agency mapping is updated on a quarterly basis and therefore some areas of the SFRA will have been supersede by more up to date mapping since when the SFRA was published.

The Environment Agency’s website also has mapping showing the risk of flooding from surface water and reservoirs. The surface water mapping does not contain sufficient information for it to be used to determine flood risk to individual properties, but it does provide an indication of whether the area may be affected by surface water flooding and to what extent.

Applicants and developers should use these sources of information alongside the SFRA.

It is the applicants responsibility to ensure all drainage designs, strategies and site-specific flood risk assessments are supported by the most accurate and up to date information on flood risk.

Oldbury on Severn Strategic Flood Risk Assessment  – Planning Policy Statement

National policy

To avoid inappropriate development in areas at risk of flooding, the National Planning Guidance (NPPF) at paragraphs 100-104 directs development to areas of the lowest flood risk. In plan making, development should not be allocated in high risk areas if there are other reasonably available sites in areas with a lower probability of flooding (Flood Zone 1) – this is the Sequential Test. If, following the application of the Sequential Test, it is not possible for the development to be located in zones with a lower probability of flooding, the Exception Test can be applied. For the Exception Test to be passed it must firstly be demonstrated that the development provides sustainability benefits to the community, which outweigh flood risk. Secondly, a site specific flood risk assessment (SFRA2) must demonstrate that the development will be safe for its lifetime (taking account of the vulnerability of its users), not increase flood risk elsewhere and where possible reduce flood risk overall.

Core Strategy and Policies Sites and Places Plan

The South Gloucestershire Core Strategy (adopted 2013) provides the strategic component of the South Gloucestershire Local Plan. It sets out the long term vision and spatial strategy for the area and the strategic policies needed to deliver sustainable communities in the period up to 2027. It provides for a minimum of 28,355 homes to be built between 2006 and 2027. Applying the Sequential Test in line with national guidance, the strategic housing locations identified to meet housing needs in South Gloucestershire have been proposed in areas with lower risk of flooding.

Through the locational strategy set out in Core Strategy policies CS5 (Location of Development) and CS34 (Rural Areas); provision was also made to enable rural communities to identify any need for small scale additional housing to meet local needs through the Policies Sites and Places (PSP) Plan or Neighbourhood Plans.

During the preparation of the PSP Plan, Oldbury-on-Severn Parish Council identified the potential for limited additional housing to meet their local needs and provide sustainable development. The parish council, in consultation with the wider community, initially identified a need for approximately 14 dwellings over and above that which would come forward under existing planning policies and permitted development including redevelopment, conversion and infill.

In response to this, South Gloucestershire Council carried out an assessment of potential housing sites at Oldbury on Severn in December 2014. This process however, identified significant constraints/issues principally in relation to flood risk – see Proposed Submission PSP Plan March 2015 (para 11.1-11.13) and supporting Sustainability Appraisal (p 67-75) South Gloucestershire Online Consultations – Draft Policies, Sites and Places Plan Summer 2014 – CONSULTATION CLOSED – Consultation Homepage

In summary, the PSP Plan evidence concluded that Oldbury village is at risk, but defended, from tidal flooding. The highest flood risk affecting the area is classified as High Probability having a 1 in 100 or greater annual probability of river flooding, also known as functional floodplain (Flood Zone 3b (FZ3b)). This area is associated with flooding from Oldbury Naite Rhine and Pickedmoor Lane Rhine, which also impacts parts of Chapel Road and Pickedmoor Lane.  All main infrastructure, including highway routes which provide access to the village are affected by flood risk, classified as either FZ3a or 3b.

There are however two areas of lower flood risk in Oldbury; one is a “dry island” adjacent to the Toot Scheduled Ancient Monument in the centre of the village and is surrounded by extensive areas of higher flood risk, and the other is to the south and is subject to Green Belt and significant heritage constraints. Potential development sites in Oldbury on Severn which are unaffected by flood risk and which met the requirements of the Sequential Test could not therefore be identified. As a result of the flooding and other constraints, and with the support of the EA, the PSP Plan did not allocate sites for additional homes in Oldbury.

Notwithstanding this, with the advice of the EA, it was agreed that if in the future, a specific local need was identified to meet the first part of the Exception Test, then further work through a detailed Strategic Flood Risk Assessment (SFRA2) could be undertaken in order to improve understanding of flood risk and inform the second part of the Exception Test which would investigate the potential for limited further development in the village.

The Oldbury on Severn SFRA2

Following the decision not to allocate through the PSP Plan, the council, working with the Environment Agency and Oldbury on Severn Parish Council, in 2017 commissioned the Oldbury on Severn SFRA2 in order to provide further detailed evidence to support the potential for small scale housing development at Oldbury on Severn.

Oldbury on Severn Neighbourhood Plan

The village has taken up the option of Neighbourhood Planning and the Neighbourhood Area was designated on 27 November 2016.

How the SFRA2 will inform planning for housing in Oldbury on Severn and the application of the NPPF Exception Test

If the Neighbourhood Planning process in Oldbury confirms a need for limited housing to meet the specific requirements of the village (supported by a technical evidence base and tested through the examination process), this will provide the justification for Part 1 of the Exception Test i.e. that the wider sustainability benefits to be afforded to the village as a result of plan led development outweigh the flood risk, although the justification remains to be tested through a Neighbourhood Plan Examination process.

It should be noted this has yet to be undertaken and is intended to be completed through the preparation of the Oldbury Neighbourhood Plan.

The primary purpose of this SFRA2 therefore is to inform the second part of the Exception Test for the Neighbourhood Planning process to ensure that any potential new development would be in areas with least flood risk and safe for its lifetime (taking account of the vulnerability of its users), not increase flood risk elsewhere and where possible, reduce flood risk overall.

The council considers that the Exception Test Part 1 will not have been met until the Neighbourhood Planning process has been completed. The council is committed to supporting the Parish Council to undertake this work through the Neighbourhood Planning process. This should therefore be afforded much weight.

The Joint Strategic Plan (JSP) and new South Gloucestershire Local Plan

The JSP and new Local Plan will update the strategic housing policies currently in the Core Strategy to meet housing need up to 2036. This includes an element of non-strategic housing in rural areas to meet the needs of the District (allocations of 10 homes and above). However, in line with national policy on flood risk and the Sequential Test, it is not considered that Oldbury on Severn will be considered for additional housing through the District wide plan making process, given the range of other locational options which are situated at a lower risk of flooding and with higher levels of sustainable access to key services and facilities.

The South Gloucestershire Council Level 2 Strategic Flood Risk Assessment for Oldbury on Severn can be viewed below.

Final report September 2017

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