Part One: Spatial Strategy and Policies

Policy DLP45 Flood Risk

1. The council will seek to minimise the probability and consequences of flooding from all sources by adopting a strong risk-based approach to site allocations and the granting of planning permission, in line with the National Planning Policy Framework.

2. The sequential test²⁶ will:
   1. be applied to all developments to ensure that development takes place in areas with the lowest flood risk, in line with NPPF requirements.
   2. take account of the most up-to-date information available on river (fluvial) flooding and all other sources of flooding, making use of the information provided in the most recent Strategic Flood Risk Assessment (SFRA);
   3. consider the impact of climate change over the lifetime of that development.
       
3. Developers should apply the Sequential Test to all development sites, unless the site is:
   1. a strategic allocation and the test has already been carried out by the LPA; or
   2. a change of use (except to a more vulnerable use); or
   3. a minor development (householder development, small non-residential extensions with a footprint of less than 250m²); or
   4. a development in Flood Zone 1, unless there are other flooding issues in the area of the development (i.e. surface water, ground water, sewer flooding). The SFRA can be used to identify where there are flooding issues from sources others than rivers.
       
4. Developers should provide evidence to the LPA that they have considered all reasonably available alternative sites that are at a lower risk of flooding prior to determining the suitability of the chosen site for the proposed development type, in relation to all sources of flood risk on it.
    
5. For all developments the vulnerability of the development type to flooding should be considered with regard to the most up-to-date flood zone information in accordance with the NPPF, as set out below:

Flood Zone 3

5. Where the site is in Flood Zone 3b (Functional Floodplain), all development other than essential infrastructure (subject to the Exception Test) will be refused (including extensions and intensification of use and changes of use) and opportunities to relocate development out of the floodplain should be sought.
    
6. Where the site is in Flood Zone 3a (High Probability), new homes can only be permitted subject to the Exception Test.
    
7. Flood Zone 2
   1. Where the site is in Flood Zone 2 (Medium Probability), most development can be permitted, subject to a site-specific flood risk assessment;
   2. Highly vulnerable developments, such as caravans, mobile homes and park homes with permanent residential use can be permitted, subject to the Exception Test;
   3. Where the site is in Flood Zone 1 (Low Probability), the information in the most up to date SFRA should be used to assess if a development is at risk from other sources of flooding and / or if there is an increased risk of flooding in the future due to climate change. If this site is shown to be at risk, a site-specific flood risk assessment should accompany a planning application.
       
8. To pass the Exception Test, developments will need to:
   1. provide a demonstrable benefit to the wider sustainability of the area. Matters such as biodiversity, green infrastructure, historic environment, climate change adaptation, flood risk, green energy, pollution, health and transport should be considered;
   2. detail the sustainability issues the development will address and how doing so will outweigh the flood risk concerns for the site;
   3. prove that the development will be safe from flooding for its lifetime, taking account of the vulnerability of its users;
   4. prove that the development can be achieved without increasing flood risk elsewhere, and, where possible, will result in a reduced flood risk overall.
       
9. All new developments in the following locations should be accompanied by a flood risk assessment and surface water drainage strategy that sets out how the development will provide a betterment in flood risk terms i.e. help to reduce flood risk both on and off site:
   1. where any part of the site is within Flood Zone 2 or Flood Zone 3;
   2. where the site is greater than one hectare and is within Flood Zone 1;
   3. where the site is within five metres of an ordinary watercourse;
   4. where the site is within 20m of a known flooding hotspot;
   5. where the site is within the 1 in 100-year flood extent based on the Risk of Flooding from Surface Water Map.
      
      Surface water drainage strategies are also required for all major developments. These should consider all sources of flooding to ensure that future development is resilient to flood risk and does not increase flood risk elsewhere.

Watercourses and flood mitigation

10. Developments should, where possible, naturalise urban watercourses (by reinstating a natural, sinuous river channel and restoring the functional floodplain) and open up underground culverts, to provide biodiversity net gain as well as amenity improvements; reference should be made to the latest River Basin Management Plans for the area.
     
11. Developers should set out how their mitigation designs will ensure that there is no net increase to fluvial flood risk downstream and where practicable how the development could help mitigate against downstream fluvial flood risk.
     
12. Development should not take place over culverted watercourses and a suitable easement should be provided from the outside edge of the culvert.
     
13. There should be no built development within five metres of an ordinary watercourse and within ten metres of the top of the bank of a main river. This is to enable the preservation of the watercourse corridor, wildlife habitat, flood flow conveyance and future watercourse maintenance or improvement.
     
14. Where there is a known or suspected culverted watercourse either on or immediately downstream of a site, where the SFRA highlights there may be a risk of flooding, developers should:
    1. confirm the location and presence of a watercourse (or otherwise) through ground-truthing strategic datasets and undertaking an assessment of the culvert extent and condition.
    2. confirm by survey, modelling and mapping, the flood extents of the watercourse(s), as many of the flood outlines associated with such watercourses have been carried out at a broad scale and may not take into account specific local features, such as culverts, bridges and detailed topographical survey.
    3. design the development to accommodate the floodplain of the watercourse and mitigate against flooding to properties on the site. This should include a consideration of residual flood risk e.g. if a culvert were to block downstream.
        
15. All developments should seek to provide wider betterment by demonstrating in site-specific flood risk assessments and surface water drainage strategies (where required) what measures can be put in place to contribute to a reduction in overall flood risk downstream. This may be by provision of additional storage on site e.g. through oversized SuDS, natural flood management techniques, green infrastructure and green-blue corridors and / or by providing a partnership funding contribution towards wider community schemes (both within Dudley, the Black Country and in shared catchments with Southern Staffordshire and Birmingham). Consultation on the site-specific requirements should be undertaken with the Council, the Environment Agency, and Severn Trent Water (where this is a sewer flooding issue) at the earliest opportunity.