5. Natural Environment

5.1 This chapter is framed around the following objectives:

Objective 2: To conserve and enhance the natural environment, biodiversity and important wildlife habitats

5.2 It presents policies, and projects, in respect of biodiversity and flood risk.

Biodiversity

5.3 The NPPF recognises the importance of conserving and protecting the natural environment. This is also reflected in the Environment Act (2021) which, coupled with the declaration of the Environment and Climate Emergency by RBWM, has raised awareness of the value and importance of biodiversity and natural habitats.

5.4 There are a number of important wildlife areas, designations and habitats in the Neighbourhood Plan area (see Figure 2) and immediately adjacent to it. These include the Cock Marsh Site of Special Scientific Interest (SSSI) and, just outside the Parish boundary, Bisham Woods SSSI and Local Nature Reserve, and the Chilterns Beechwood Special Area of Conservation: a site designated for protection at the European level (see mapping in Appendix 4). The Parish also includes a number of priority habitat areas, including areas of grassland, marsh and woodland. These extend beyond Cookham Parish and create a network of connected habitats (see mapping in Appendix 4). The quality of soils in the Parish is also important for biodiversity, with approximately 50% of organisms occupying the soil.

5.5 Locally, a number of actions to improve biodiversity have been identified in the RBWM Biodiversity Action Plan (see Box 5) and which biodiversity net gain plans should seek to support.

INFORMATION BOX 5: Biodiversity Action Plan

The RBWM Biodiversity Action Plan (BAP) covers the period 2022-26. Projects and initiatives identified in the BAP are supported by the Parish Council, and developers are encouraged to help deliver these where appropriate to proposals. It is recommended that the use of pesticides and herbicides be avoided within Cookham Parish on any public or private land to spare the environment. Objectives defined in the draft updated BAP include, but are not limited to:

Increasing the area of woodland, trees and hedgerows through planting.
Protect and provide better management for existing woodlands and grassland.
Encourage the creation and enhancement of biodiverse grasslands, woodlands, hedgerows and waterways.
Identify opportunities to enhance the biodiversity value and carbon sequestration of existing grasslands.
Develop a Habitat Action Plan with landowners and farmers to implement environmental best practice.
Enhance the biodiversity value of existing waterways, manage and eradicate non-native invasive species.
Increase numbers of wildlife ponds for the benefit of all wildlife.
Encourage the creation and enhancement of biodiverse standing water, and prevent and reverse degradation of waterbodies from non-native invasive species.
Protect locally designated sites, and identify land to be protected to achieve protection and enhancement of 30% of the land in the Borough for biodiversity.
Reduce the use of herbicides and pesticides on roadside verges and in parks.

Within built-up areas, the following objectives are identified:

Ensuring permeability for hedgehogs, small mammals and amphibians across the borough.
Improve ecological connectivity through no net loss of roadside verges.
Decrease lighting to positively impact bats and other nocturnal animals.
Integrating bat and bird boxes in new development and creating suitable foraging and commuting habitats for bats and birds.
Increasing the number of green walls and roofs.
Increasing biodiversity in all Council-owned parks, to include new wildlife areas, fruit and herb gardens.

Policy C-EN1: Biodiversity

Other than where exempt by national guidance, development proposals must manage impacts on biodiversity and secure a minimum net biodiversity gain of 10% on-site where practicable, as demonstrated through use of the most up-to-date version of the Defra biodiversity metric (or any successor document to this).
Where it is not practicable to deliver biodiversity net-gain on-site, off-site measures must be provided. These should be located within the Parish, but where this is not possible, they should be located as close to the development site as practicable.

Green infrastructure, habitats and corridors

5.6 Cookham Parish is surrounded by three significant and distinct areas of habitat: the River Thames, suburban Maidenhead and the Bisham Woods. Within the Parish, the built-up areas create barriers to the free movement and/or spread of flora and fauna, potentially creating species isolation which can result in in-breeding, a breakdown in ecological resilience and degrading biodiversity. Intensive farming on arable land creates additional barriers.

5.7 Development should be planned in such a way that avoids habitat loss and fragmentation, and opportunities should be sought to improve ecological connectivity, including through the creation, restoration and enhancement of linking habitats and ‘stepping stones’ through the landscape.

5.8 Identifying and securing wildlife or green corridors is essential to ensure the necessary replenishment and maintenance of species diversity for healthy ecological functioning. The aim of the corridors is to provide connectivity between major habitat areas of open water and woodland. Green corridors in the Plan area are illustrated in Figure 3 with more information presented in Table 1.

Green Corridors (Figure 3)

Map Ref (Figure 3)	Name of Corridor	Connected Habitat Name (Figure 3)	Connected Habitat Type	Corridor Type	Type of Habitat/Species Created For
A	Bradcutts Lane	Cockmarsh (1) and Hillgrove Wood (4)	Dry grassland w/ older trees	Hedgerow	Heathland, grassland and mature woodland
B	Halloween	Winter Hill (2) and Hillgrove Wood (4)	Woodland	Hedgerow	Mature and semi-mature woodland
C	Railway with embankments	-	Hedgerows and gardens	Grassland	Insects and wildflowers
D	West of Whyteladyes Lane	Hillgrove Wood (4) and Pigeonhouse Wood (6)	Woodland and gardens	Trees and hedgerow	Semi-mature woodland
E	White Place Farm	Sashes Island/Odney (5) and Battlemead (8)	Wet meadows, woodland	Trees and hedgerow	Meadows, wetland and woodland
F	Long Lane	Pigeonhouse Wood (6) and Beeching-grove Wood (9)	Woodland	Hedgerow	Semi-mature woodland
G	White Brook Strand Water Marsh Meadow	Widbrook (7)/Battlemead (8) and River Thames	Stream, ponds and wetlands	Stream and banks	Aquatic, amphibians, insects etc.
H	Malders Lane and Switchback Rd	Pigeonhouse Wood (6) and Beeching-grove Wood (9)	Woodland	Hedgerow	Semi-mature woodland

Table 1: Green Corridors in Cookham Parish

5.9 The most obvious natural corridors through Cookham are (i) the railway line, linking waterway and wetland habitats around the river and the adjoining chalk grassland common land and providing a valuable wildlife route through the heart of Cookham, and (ii) the waterway leading from its outlet from the River Thames at Marsh Meadow along the Fleet Ditch and Strande Water through to the junction with Widbrook to create the Maidenhead Ditch. This stream links important habitats along its journey through to Widbrook Common and areas in North Maidenhead. Whilst these two corridors have a large degree of protection due to their inherent nature and location, there are other valuable but more at-risk corridors connecting wildlife habitats to the north and west of the Cookham settlement, notably the chalk grassland of Cockmarsh (ref 1, Figure 3), Winter Hill and the Bisham Woods Special Area of Conservation (ref 2, Figure 3) and the Local Wildlife Sites woods (ref 6 and 9, Figure 3). The corridors linking these facilitate wildlife movement via woodland and existing hedgerows, and importantly link to hedgerows providing routes between the higher ground of Cookham Dean and the floodplain.

5.10 Most of the green corridors in the Plan area consist of hedgerows with or without trees. The railway embankments along the line from Maidenhead to Bourne End have a very useful role to play for corridors, providing contiguous and uninterrupted semi-natural habitats.

5.11 Development adjacent to or surrounding these areas should help support the enhancement of habitats through a positive approach to conservation management.

5.12 As a general steer, where a corridor is shown as following a watercourse, its width would normally be considered to be around six metres on either side of the edge of the watercourse in line with guidance from the Environment Agency, extending to around ten or twelve metres where there are upslope pollution pressures. Where a corridor does not follow a watercourse, its width would generally be considered to be around ten metres. The width of corridors supports the uninterrupted migration of land-based species such as badgers, deer, reptiles and amphibians, but also enables the establishment of ‘stepping stone’ habitats to allow all species, including avifauna and insects, to migrate to larger corridor areas. Opportunities that help overcome current barriers to wildlife movement, including those created by the railway line, will be welcomed.

5.13 Information on planning for green infrastructure and wildlife habitats is set out in the Cookham Design Guidance and Codes. This shows how new (and existing) development might help create connected green corridors through:

Provision of front and back gardens including permeable surfaces and planting of local species of trees and shrubs.
Alignment of back gardens where possible to provide for continuous wildlife corridors, with bird (including those for swifts) and bat boxes or bricks in walls installed to enhance biodiversity and wildlife.
Retention of existing green spaces and provision of new green spaces within walking distance of new developments, which should be carefully located in order to maximise their potential as a habitat for wildlife.
Retention of, and planting of new trees (enabling natural regeneration where practicable) and hedgerows in the countryside and agricultural areas, supporting the resilience of green network.
Safeguarding of water bodies and natural open spaces from potentially damaging human interaction.

Policy C-EN2: Green Infrastructure and Corridors

Development proposals should seek to retain existing trees and hedgerows in their layouts. New planting should comprise native species appropriate to the area.
Where there is unavoidable loss or damage to habitats, sites or features because of exceptional circumstances, mitigation and compensation will be required, including replacement on site with semi-mature, native species or equivalent planting.
New green infrastructure must provide permeability for wildlife. It should be functional as a wildlife habitat in its own right and not just as a link between habitats. The width of wildlife corridors should take account of the requirements of target species and should allow for movement of nocturnal wildlife, minimising the impacts of lighting and glare.
Development should maintain and enhance wildlife spaces. Development proposals should demonstrate how the connectivity and function of the green corridors indicated on Figure 3 and shown in more detail on Figure 4 – Figure 11 will be maintained and, where possible, enhanced.

Flood Risk

5.14 Large parts of the Parish are at risk from fluvial and/or surface water flooding.

5.15 Though Cookham Village itself is on slightly higher ground, it is entirely surrounded by low-lying ground. This has the effect of isolating the settlement in all directions during flooding conditions, with the Causeway between Cookham Village and Cookham Rise the only means of access. It is thus important that this route is maintained to allow access at times of flooding (see Projects in Appendix 8).

5.16 The Local Plan, through Policy NR1 (Managing Flood Risk and Waterways), requires any development proposals situated on land designated as Flood Zone 2 or 3 to be able to demonstrate that an appropriate flood risk assessment has been carried out. The policy also notes that development proposals should incorporate Sustainable Drainage Systems (SuDS) in order to reduce levels of surface water run-off. SuDS are an approach to managing surface water run-off which seeks to mimic natural drainage systems and retain water on or near the site as opposed to traditional drainage approaches which involve piping water off site as quickly as possible.

5.17 The Construction Industry Research and Information Association (CIRIA) has produced comprehensive and technical guidance on the design and delivery of SuDS (C753: The SuDS Manual 2015).

5.18 The RBWM Borough Wide Design Guide recognises the value of SuDS not just in mitigating the risk of flooding, but also in contributing to a diverse and high-quality network of open spaces. Indeed, the use of SuDS can help contribute towards achievement of biodiversity net gain on development sites, as well as comprising a wider response to climate change and resilience. This may include the use of SuDS as ‘raingardens’ within the public realm as part of wider highways projects. These are generally low maintenance, wildlife-friendly spaces that manage rainwater runoff from hard surfaces and are also often referred to as bioretention facilities.

5.19 A range of design responses and SuDS techniques may be appropriate and can be explored through the design process. These include, but are not limited to, the use of permeable pavements, tree pits and planters, raingardens, swales, basins, ponds and rills. The integration of SuDS features on buildings can also be considered, including green/living roofs and walls, rainwater planters, water butts and tanks. Where SuDS features are proposed as part of the building, consideration should be given to structural safety and ongoing maintenance as set out in the CIRIA SuDS Manual.

Policy C-EN3a: Flood Risk

Development should avoid, as far as possible, flood risk to people and property. Where Flood Risk Assessments are a requirement of development proposals, these should incorporate:
1. Assessment of flood risk based on the drainage and water disposal profile of the site and neighbourhood area.
2. Assessment of flood risk based on current and future impacts of climate change.

Policy C-EN3b: Sustainable Drainage Systems (SuDS)

Proposals for major development should demonstrate that:
1. There is adequate water drainage infrastructure to serve the development, without surcharge of foul drainage.
2. There will be no adverse impacts from flood risk, including surface water flood risk, on adjoining, upstream or downstream land.
3. Mechanical pumping is not required in order to prevent flood impact, in the event of up to and including a 1 in 100 year event.
Where SuDS are proposed as part of any development:
1. The design of SuDS should take account of guidance established in the CIRIA SuDS Manual (or a subsequent update of this).
2. SuDS should be designed to be multi-functional and deliver benefits for wildlife, amenity and landscape.
3. Where it is proposed to provide SuDS within the public realm these should be designed as an integral part of the green infrastructure and street network, responding positively to the character of the area.

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