Open Spaces Supplementary Planning Document

Chapter 6 Open Spaces and the Water Environment

Open Spaces and the Water Environment

River Corridors and Riparian Areas

6.1 Many of the Local Plan development allocations have watercourses either adjacent or running through the sites. Open space provision will often be centred around these areas. Not exclusively, this is because:

  • development of built infrastructure should be directed away from areas at risk of flooding (Local Plan Policy EM4);
  • development of built infrastructure should be set back at least 8m from Main River and 5m from ordinary watercourses (EM4);
  • where a development proposal lies adjacent to a river corridor or tributary, a natural sinuous river channel should be retained or, where possible, re-instated (GE1);
  • all opportunities to undertake river restoration and enhancement including de-culverting, removing unnecessary structures and reinstating a natural, sinuous watercourse will be encouraged (EM4); and
  • both Keresley and Eastern Green SUE's require publicly accessible green and blue infrastructure corridors along the brooks running through these allocations (see Local Plan Policy DS4 parts C and D, and Local Plan Table 4.2).

Sustainable Urban Extension SPD

6.2 The natural landscape section of the Coventry Urban Extensions Design Guide (page 89) provides guidance on blue infrastructure.

6.3 Blue infrastructure will provide a key component of incorporating high quality design as well as supporting the overall drainage and flood risk strategy. This can take the form of individual pools, or in the case of Keresley and Eastern Green in particular existing and established brook corridors. These brook corridors should become focal points for the green and blue infrastructure strategy and provide a high quality useable route through the wider developments - connecting with the wider natural landscape both within the sites and beyond. They should incorporate high quality footpaths and cycle ways whilst also providing a magnet for ecology and biodiversity to thrive across the sites.

River restoration and natural morphology

6.4 The Lead Local Flood Authority can provide advice and guidance on river restoration requirements. This may include site specific mitigation measures to help achieve the requirements of the Water Framework Directive.

6.5 Access routes and other greenspace assets are encouraged within river corridors. When locating these, the natural morphology of the river should be considered. Features should either be located away from areas where the river may encroach over time, or be easily movable. This is to avoid:

  • damage to assets and associated replacement costs; and / or
  • costly and inappropriate river engineering
  • Allowing river channels to naturally migrate over time is always preferred if possible.

Consideration of flood risk within Green Spaces

6.6 As well as often being located adjacent to rivers and watercourses, greenspaces are often located within other areas not appropriate for development due to flood risk, such as surface water flood risk areas and exceedance flow routes. Areas may also be designed to flood, such as flood storage areas and SuDS.

It is stated within national flood risk guidance:

6.7 "Amenity open space, nature conservation and biodiversity, outdoor sports and recreation and essential facilities such as changing rooms" are described as water compatible in national guidance and therefore appropriate for siting within flood risk areas.

6.8 Consideration should be given in design to use of the greenspace during and after flood events. For example:

  • In areas of high flood risk, flood warning signs should be considered warning users they may be temporarily affected.
  • Key assets should be located in areas where flood water dissipates quickly after storm events. There may be locations where flood water will remain for longer periods, for example where floodplain does not drain freely back to a river due to site levels.
  • Where flood water dissipates, greenspaces may still remain saturated for a time after flood events. Most soils in Coventry are clayey not freely draining. This should be considered in design, for example, through provision of hard surfaced footpaths.
  • Flood water also has the potential to be contaminated or carry debris and refuse. This should be considered within landscape management and maintenance plans.

6.9 The intended use of greenspaces should be compared with flood risk information provided in a site specific flood risk assessment, including flood risk hazard ratings.

Existing ponds

6.10 Existing ponds should usually be retained as part of greenspaces, and not be used or enhanced as SuDS.

Sustainable Drainage Systems in Greenspaces

6.11 As is stated in the Local Plan "SuDS involve a range of techniques that mimic the way that rainfall drains in natural systems and avoids any increase in flood risk and improves water quality."

6.12 In policy EM5 it is stated "all development must apply SuDS and ensure that surface water runoff is managed as close to its source as possible".

6.13 The Councils' preference is for above ground SuDS which deliver multiple benefits. SuDS are therefore often located within development greenspaces.

Design considerations relevant to open spaces

6.14 More detailed design requirements for SuDS are provided within the Coventry SuDS in design guide (in draft). Standing advice is available here:

6.15 SuDs in greenspaces should bring amenity, landscaping and biodiversity benefits as well as the water management elements required. They can be designed to meet wider greenspace requirements, such as for the provision of biodiversity for net gain requirements, or to be used as joint use amenity spaces.

6.16 They should interface well with the surrounding space and be incorporated into usable green space for most of the year. For example; pathways running the perimeter of ponds to allow people to interact with the feature.

6.17 Other requirements pertinent to greenspaces are:

  • SuDs should usually be built within the natural ground conditions.
  • SuDS storage should not usually be located within areas of fluvial flood risk.
  • Given they are located in publicly accessible areas, design for safety is paramount.

Adoption and maintenance

6.18 The adoption and maintenance of all drainage features are a key consideration to ensure the long-term operation at the designed standards. Underground drainage infrastructure such as pipes and tanks will be considered for adoption by a Sewerage Undertaker. The Council will consider the adoption of open-air sustainable drainage within areas of public open space, (subject to a commuted sum). Such features could include semi-dry detention basins which form joint-use amenity space. Open attenuation features must be accessible by appropriate maintenance vehicles and require a maintenance strip with a minimum width of 3 metres, and potentially wider to suit the specific development.

Severn Trent Water now adopt certain SuDS, but only the functional drainage aspects of them

6.19 SuDS within greenspaces have unfortunately been mistreated by residents in certain areas in the past, particularly for the disposal of rubbish. Consideration should be given to this within asset maintenance plans.

Developer contributions

6.20 The Council may seek developer contributions related to greenspaces and water. Contributions are sought to reduce flood risk and deliver improvements to the water environment, with benefits for both people and nature, safeguarding against the future impacts of climate change and development creep.

6.21Paragraph 34 of the NPPF 2021 discusses contributions. - Plans should set out the contributions expected from development. This should include for flood and water management and green infrastructure. Such policies should not undermine the deliverability of the plan.

In what circumstances will development contributions be sought?

When, why, where and how?

6.22 Developer contributions will only be sought where they meet all of the following tests from NPPF para. 56:

a) necessary to make the development acceptable in planning terms;

b) directly related to the development; and

c) fairly and reasonably related in scale and kind to the development.

6.23 Contributions may be considered for both on-site and off-site requirements, consistent with Local Plan Policy IM1: The Council will, where appropriate, seek to secure site-specific infrastructure investments and/or contributions as well as off-site contributions and/or investments. In accordance with NPPF para 53, contributions will only be sought where they are directly related to the development.

On-site SuDS, watercourses and other assets

6.24 As stated in Local Plan Policy IM1, The Council will, where appropriate, seek to secure site-specific infrastructure investments and/or contributions, contributions as well as off-site contributions and/or investments.

6.25 Where the Local Authority will maintain SuDS, watercourse or other assets on-site, contributions will be required to support ongoing maintenance over the lifetime of the development.

6.26 Account will also be taken of the ease of maintaining a system according to its design, with reference to health and safety. Some assets will need more frequent maintenance or replacement; therefore, this will be taken into consideration when setting the term over which a contribution will be required.

6.27 Where SuDS are combined with amenity or biodiversity or provide such benefits lower contributions may be applied. If separate, then the rate will reflect the full cost and if any manufactured product is used maintenance costs will be based on the recommended manufacturer's regime and relevant technical guidance (e.g. CiRIA SuDS Manual).

6.28 Contributions will be tailored towards the development proposals and contributions will be advised. Contributions are normally negotiated at the pre-application, outline or full application stage where matters of principle are established. In all cases we encourage applicants to seek pre-application advice from the LLFA; the details of which can be found on the Council's website here:

6.29 Depending on the situation, it may also be beneficial to seek pre-application advice from other risk management authorities such as the Environment Agency.

Additional flood storage

6.30 In accordance with Local Plan Policy EM4(2) "All opportunities to reduce flood risk in the surrounding area must be taken, including creation of additional flood storage. In this instance reference should be made to the Council's Infrastructure Delivery Plan (IDP) or regulation 123 list."

6.31 In the IDP, under Water and Flood Mitigation, a city-wide Flood Prevention programme is listed as a Category 1 item (essential infrastructure) to "Prevent/mitigate potential issues in the future and resolve existing issues. To ensure all homes, business and public spaces are free from flood risk".

6.32 Additional flood storage therefore may be required in greenspaces. Other entries in the Plan under the Water and Flood Mitigation, and Green and Blue Infrastructure sections are relevant, including site specific schemes. A site-specific evaluation will be required to determine the necessary mitigations of the specific flood risk within the catchment associated with the new development.

River and catchment restoration including de-culverting

6.33 In accordance with the Local Plan policy EM4(2c) which refers to the surrounding area, "all opportunities to undertake river restoration and enhancement including deculverting removing unnecessary structures and reinstating a natural, sinuous watercourses will be encouraged". For example, a contribution may be sought to secure the deculverting of watercourse to secure flood and water management benefits. Reference should also be made to the Green and Blue Infrastructure section of the IDP.

Watercourse access

6.34 A contribution may be sought for supporting the creation or improvement of access and linkages to river corridors for maintenance and amenity purposes.