Ended on the 18 March 2021
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Chapter 9: Conserving and Enhancing the Environment

(3) Conserving and Enhancing the Environment

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Figure 9.1: Green infrastructure in Watford

9.1 Although Watford is a densely populated urban borough, the natural environment is relatively rich. There are many high quality and high value open spaces, including 12 Green Flag parks, ancient woodland and sites of national and regional significance. Two rivers run through the borough, as well as the Grand Union Canal, which stretches from London to Birmingham. Watford supports wider green and blue links to other natural areas of significance in the region, including Colne Valley Regional Park and the Chilterns Area of Natural Beauty. Urban planning can be an important instrument for the natural environment, for it seeks to balance the need for new development while also striving to conserve and enhance the natural environment.

9.2 Designated green infrastructure and open spaces in Watford are shown on Figure 9.1. Ecological resources and opportunities have been identified and mapped as part of data held by the Hertfordshire Ecological Records Centre. This data includes species and site records and maps, as well as the Local Nature Partnership's Network Mapping.

(4) Strategic Policy NE9.1: The Natural Environment

The Local Plan will support the conservation and enhancement of the natural and local environment. Development proposals will be required to demonstrate a positive impact on Watford's natural environment by:

  1. Protecting and enhancing Watford's natural and environmental assets and seeking to create new environmental features where possible;
  2. Conserving and enhancing the extent and quality of green infrastructure and ecological networks by seeking to create, expand and restore links within the network, and support the wider benefits from natural capital and ecosystem services at a landscape scale where appropriate;
  3. Ensuring all new development minimises impacts on biodiversity and achieves a measurable biodiversity net gain, locally, where possible;
  4. Following the 'mitigation hierarchy' of avoidance, mitigation or compensation as appropriate;
  5. Maximising the role of watercourses for leisure, recreation and active travel purposes, as well as seeking to enhance their water quality and biodiversity value;
  6. Minimising the risk of flooding, including surface water flood risk;
  7. Bettering access to open space across the borough where there is an identified need and delivering new green spaces as part of new development;
  8. Delivering non-traditional forms of urban greening as part of high density development, as well as traditional open space, including green roofs and walls;
  9. Improving the quality of Watford's existing open spaces through development contributions;
  10. Where necessary, ensuring that protected species and their habitats are a material consideration when determining planning applications; and
  11. Protecting trees and encouraging native planting on new development; and
  12. Considering the cumulative impacts of development on green and blue infrastructure.

The green infrastructure network

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9.3 Green infrastructure is defined as multi-functional networks of open spaces, green corridors and natural green space. Together, these networks perform a variety of functions for the environment and the people who live here. The importance of green infrastructure is highlighted in Figure 9.2. Watford's green infrastructure network contains critical links across the borough, but also across wider Hertfordshire and beyond.

9.4 To conserve and enhance the green infrastructure network, new proposals adjacent or in close proximity to open space and green corridors should consider the impact of development on existing networks and prevent fragmentation. New development can help deliver enhancements to the green infrastructure network and improve connectivity between green spaces if opportunities are proactively identified in the early stages, as proposals are being drafted. The potential impact of landscaping, access, excessive lighting, overshadowing and noise should also be considered and appropriate mitigation provided to protect the intrinsic quality of the network.

9.5 Opportunities to improve the green infrastructure network have been set out in the Green Infrastructure Plan and have been illustrated on Figure 9.1. The projects identified are:

  • Cassiobury Park enhancement;
  • Whippendell Woods enhancement;
  • Grand Union Canal enhancement;
  • Colne Valley Wetland enhancement;
  • Urban greening and legibility for Watford.

9.6 Trees also make an important contribution to biodiversity and should be protected where possible to support the government's England Tree Strategy (2020). Opportunities should also be taken to increase native planting to support biosecurity.

(6) Policy NE9.2: Green Infrastructure Network

Proposals must demonstrate how they will appropriately conserve, restore, expand or enhance the green infrastructure network, including how the site connects with the wider network. Development should protect the function and amenity of green routes, including public rights of way.

A proposed loss or damage of non-protected trees, woodland or hedgerows should be avoided, and if demonstrated as being unavoidable, appropriate replacement or compensation will be required. Native planting should be prioritised.

Priorities for green infrastructure focus on the projects identified in the Green Infrastructure Plan.

(1) The blue infrastructure network

9.7 The Grand Union Canal, River Gade and the River Colne all flow through Watford and form the borough's blue infrastructure network. Rivers Colne and Gade are designated as main watercourses by the Environment Agency, whereas the Grand Union Canal is designated as an ordinary watercourse for the length it runs through Watford. Protecting and enhancing these watercourses is important for many reasons, such as to effectively manage flood risk, to conserve and enhance river habitats and to maximise opportunities for active travel and leisure. The Water Framework Directive (WFD) also sets an objective to improve these watercourses to 'good' status by 2027.

9.8 During the plan period, there is expected to be new development occurring near to Watford's watercourses and their corridors. High quality development presents an opportunity to enhance the role of watercourses and make them a central feature of new development. This would maximise the contribution that blue infrastructure can make to creating successful places.

9.9 New development also presents an opportunity to enhance the quality of watercourses, to support them achieving Water Framework Directive 'good' status within the established timeframe. The potential impact of landscaping, access, lighting, overshadowing and noise should be considered and appropriate mitigation provided to protect the intrinsic quality of the water environment. This is particularly pertinent for taller buildings, which can overshadow rivers and result in the loss of habitats.

9.10 Development that occurs too close to the banks of watercourses can increase the risk of pollution and limit capacity to manage run off. The South West Hertfordshire Strategic Flood Risk Assessment Stage 1 (2018) identifies the need for 8m undeveloped buffer zones between the top of the bank of any main watercourse and the built environment (including formal landscaping, sport fields, footpaths, lighting and fencing). The buffer zone must be free of hard standing, paths or lighting and must not be used for storage of materials. Planning conditions will require the developer to provide details of an appropriate management scheme to ensure that the buffer is well maintained.

9.11 Many of Watford's watercourses have been culverted, to support historic development and infrastructure projects. However, the culverting of watercourses can be harmful for the ecology, as it creates barriers to the movement of fish and causes the loss of bankside habitats.[4] Culverts also contribute to an increased risk of blockage, which in turn, increases flood risk. As new development comes forward, it is important that deculverting and the re-naturalisation of the watercourse occurs as much as possible to improve the water environment. Culverting, among other issues, has meant that routes for cyclists and pedestrians along canals are also relatively fragmented. New development can help deliver enhancements to watercourses and their corridors by providing new connections and routes for active travel and leisure uses and by enhancing interconnectivity with the green infrastructure network.

9.12 This policy should be read in conjunction with Policy NE9.4 'Flood Risk and Mitigation', which provides more detailed guidance on mitigating flood risk.

(3) Policy NE9.3: Blue Infrastructure Network

Development proposals in close proximity to watercourses must support the strategic importance of Watford's blue infrastructure network and seek to maximise its multifunctional environmental, social and economic benefits. Development proposals in close proximity to, or that include a watercourse must:

  1. Maintain an undeveloped and unobstructed buffer strip of eight metres from the top of the bank of all watercourses. Where this enables public access, proposals should be accompanied by a management plan;
  2. Conserve and enhance the biodiversity value of the watercourse and its corridor through the inclusion of in-channel enhancements, the creation of priority wetland habitats, prioritising native planting schemes and by addressing misconnections;
  3. Enhance the role of the watercourse as an accessible active travel and leisure route for pedestrians, cyclists and boaters, and increase connectivity along the length of the watercourse. This includes connectivity and access, where appropriate, to the green infrastructure network;
  4. Integrate the watercourse into the scheme as a vital part of the public realm; and
  5. Open and re-naturalise modified watercourses, including culverted and piped waterways.

The provision of crossings and bridges will be supported where they improve connectivity for pedestrians and cyclists, are in keeping with the setting of the area, and are designed to avoid obstructing flood flows.

(1) Flood risk and groundwater management

9.13 The National Planning Policy Framework supports a risk-based, sequential approach to manage flood risk and ensure development is located in areas of lowest risk. Along with the Flood and Water Management Act (2010), there is a requirement for new development to minimise vulnerability and improve resilience to the impacts of climate change including flooding.

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Figure 9.3: Flood Zones with climate change allowances in Watford

Flood risk

9.14 Flood zone classifications reflect the local risk to people and property and indicate types of development that may be suitable in that zone due to risk level. In Watford, zones of fluvial and surface water flood risk and groundwater protection are identified in the Level 1 (2018) and Level 2 (2020) Strategic Flood Risk Assessments. These areas are largely, but not exclusively, associated to the water basins of the Rivers Colne and Gade.

  • Sites located within Flood Zone 1 are subject to lower levels of flood risk, however, they may still require a Flood Risk Assessment where new development could affect the floodplain and increase risk on site or on other sites nearby. A sequential test may be required for development where there is a previously identified flood risk issue.
  • Development located in Flood Zones 2 and 3 is at high risk of flooding. Site specific Flood Risk Assessments are required for all developments within these zones. Development should be prioritised outside of these areas, however, where this is not possible, sites will need to comply with Sequential and Exception Test requirements, as appropriate, before planning permission can be granted.

9.15 Flood risk should be discussed when development proposals are prepared. Applicants are expected to consider how their proposals affect, or could potentially impact other sites in the vicinity and the cumulative impact on flood risk. In some circumstances this may require further modelling to determine the overall impact and potential mitigation measures that may be needed. Developments should seek betterment of existing flood risks, both within the site and in the surrounding area. External organisations such as the Environment Agency and the Lead Local Flood Risk Authority (Hertfordshire County Council) should be consulted to provide guidance when required.

Groundwater protection

9.16 The River Colne basin is designated as Groundwater Source Protection Zone 1, most sensitive with an area buffering the waterway covering much of east Watford identified as Groundwater Source Protection Zone 2 and sensitive to contamination. This means several land uses including industrial, petrol stations and waste management may not be suitable in certain areas of Watford due to the high risk of contamination to the aquifer and drinking water. Developers are expected to implement measures to minimise these potential negative impacts on the ground source. Where these are required these should be prepared in collaboration with the Environment Agency and the Lead Local Flood Authority.

Flood risk mitigation

9.17 There are different causes that can trigger fluvial, surface and ground source flooding, and appropriate mitigation measures are required to reflect this. Proposals located in different parts of the borough that are subject to any type of flood risk will need to consider suitable measures to minimise the potential impacts. This should include measures to address safe access and egress, particularly for changes of use to a 'more vulnerable' classification (e.g. commercial to residential). These should satisfy the requirements set out in the Hertfordshire Local Flood Risk Management Strategy (2019) and should be prepared in collaboration with the Environment Agency.

9.18 Developments located in Flood Zones 2 or 3 are encouraged to have early and ongoing discussions with the Environment Agency (EA) and Lead Local Flood Authority to ensure proposals comply with their requirements. New residential developments should be designed to withstand a 1-in-100 year flood, plus a 35% climate change allowance while considering the impacts of plus 70% climate change during the process, to ensure longevity and safety of the development over time.

Sequential and Exception Tests

9.19 Sites designated for development in this Plan have already been put through the Sequential and Exception Tests. However, the Exception Test may need to be reapplied if relevant aspects of a proposal were not considered initially. Windfall sites located within Flood Zones 2 or 3, or sites within Flood Zone 1 where there is an identified flood risk, which have not been subjected to Sequential and Exception Tests, will be required to do so.

(4) Policy NE9.4: Flood Risk and Mitigation

Fluvial flooding

When located within areas identified as being at risk of flooding, applicants are required to demonstrate how appropriate and effective mitigation measures have been integrated into the scheme, including management of residual flood risk.

Proposals located within flood zones, need to meet the requirements of the Sequential and Exception Tests. To demonstrate compliance with the Exception Test, a flood resilient design and emergency planning considerations will need to be accounted for, over the lifetime of the development including:

  1. The development to remain safe and operational under flood events;
  2. Safe evacuation and/or safely remaining in the building under flood conditions;
  3. Key services must continue to be provided under flood conditions; and
  4. Buildings are to be designed for quick recovery following a flood.

Any development within Flood Zones 2 and 3, and those over one hectare in Flood Zone 1, should use a Flood Risk Assessment to show how they have considered flood risk beyond the site boundaries, including cumulative impacts arising from other developments. Proposals should demonstrate that suitable flood compensation storage is available to avoid any net loss in floodplain.

Proposals located in areas where waterways have been culverted or altered should seek to re-naturalise the river and surroundings, improve water storage and enhance riparian habitats, in line with requirements to meet Water Framework Directive objectives and the Thames River Basin Management Plan. Flood defences within the site boundary must be maintained, repaired or replaced by the developer for the lifetime of the development.

Groundwater protection

Where a proposal is located within a Groundwater Source Protection Zone, applicants will be required to demonstrate there will be no significant impacts. If a potential impact is identified, appropriate mitigation measures need to be incorporated as part of the scheme. Within Source Protection Zone 1 (SPZ1), deep infiltration soakaways should be the last resort. Certain discharges into the ground may require an Environmental Permit.

9.20 In some instances, following the application of the Sequential Test, it may be necessary for a developer to make a contribution to the improvement of flood-management provision that would benefit the proposed new development and the existing community. Where a proposed development is deemed to have a harmful impact on flood risk, a contribution towards flood mitigation may be required through planning conditions.

(1) Surface Water Management

9.21 A well-considered drainage strategy plays a vital role in the management of surface water flood risk. Sustainable Drainage Systems (SuDS) are water-management measures that use natural methods designed to manage surface water as close to the source as possible. To be effective, a Sustainable Drainage System can be designed to use a combination of approaches including rainwater collection, grey water recycling, infiltration, soakaways, bio-swales and discharge to a watercourse as appropriate. Design requirements for effective drainage systems can be found in the CIRIA (Construction Industry Research and Information Association) SuDS Manual (2015) and Hertfordshire Local Flood Risk Management Strategy (2019).

9.22 Sustainable Drainage Systems should be multifunctional in their approach and be designed to maximise their benefits in other areas such as biodiversity and useable space for periods when they are not actively managing water for flood risk. Sustainable Drainage Systems can also aid in pollution mitigation when implemented correctly, but it is important that they are designed carefully to avoid contamination. For example, soakaways should not be implemented on contaminated land and infiltration should only be incorporated when using uncontaminated water. A surface water management plan is necessary to ensure Sustainable Drainage Systems are effectively designed, maintained and monitored.

9.23 The quality and effectiveness Sustainable Drainage Systems can vary. The hierarchy below sets out an approach that should be considered where a scheme could use single or multiple measures. From preferable, to least preferable:

  1. storage rainwater for later use
  2. use of infiltration measures, such as porous surfaces in non-clay areas
  3. attenuate rainwater in ponds or open water features for gradual release
  4. attenuate rainwater by storing in tanks or sealed water features for gradual release
  5. discharge rainwater direct to a watercourse
  6. discharge rainwater to a surface water sewer/drain
  7. discharge rainwater to a combined sewer.[5]

9.24 Where management and maintenance of Sustainable Drainage Systems are required, the applicant should set out how this will be approached. This will need to be discussed with the appropriate stakeholders and required through the use of planning conditions.

9.25 Site specific and Strategic Flood Risk Assessments for surface water management should consider both central and upper-end climate change allowances as stated in the National Planning Policy Framework. Details on the locations and necessary allowances are provided in the most recent Strategic Flood Risk Assessment. Predicted climate change allowances are increasing with time, and developments must consider this increase based on the expected duration of the structure.

(4) Policy NE9.5: Surface Water Management

Proposals that incorporate well-designed Sustainable Drainage Systems that are appropriately integrated into the scheme, aim to achieve greenfield run-off rates manage surface water and improve resilience will be supported.

Sustainable Drainage Systems should make effective use of land by being multifunctional, to maximise ecological benefits such as biodiversity, provide open space or incorporate tree planting and landscaping. Developments will need to ensure the implementation of Sustainable Drainage Systems does not worsen contamination effects, and soakaways should not be located within land affected by land contamination. Details of the Sustainable Drainage System should be submitted to the Council as part of the Sustainability Statement.

Developments should seek betterment of existing surface water flood risk, both within the site and surrounding area, as an opportunity to have a positive impact on cumulative risk, using appropriate drainage measures. Allowances for changes and increases in flood risk due to climate change need to be considered. Sustainable Drainage Systems must be designed to respond to risk for the lifetime of a development, including the appropriate climate change impacts.

Sustainable Drainage Systems should be designed and integrated into the proposal to effectively manage the existing surface water flow paths on the site and help to mitigate other flood risks. Measures should be agreed with the lead flood risk authority and be consistent with the Hertfordshire Local Flood Risk Management Strategy. As part of an application, an applicant should provide a management plan that clarifies how any measures will be managed and maintained and agreed with the lead Local Flood Risk Authority.

(1) Protecting open space

9.26 Watford's open spaces are a great source of pride for our communities. Our award-winning parks are not the only types of green spaces that Watford's residents can enjoy, as the borough contains a wide variety of types of open space. From allotments to playing pitches, these different open spaces can provide for a variety of different uses, functions and activities. Open space can make an important contribution to the green infrastructure network and offer valuable space for recreational and amenity use. Open spaces can also contribute towards flood risk management schemes and sustainable drainage systems.

9.27 Everyone living, working in and visiting Watford should have access to high quality open space and sports and recreation facilities. The types of open spaces provided and protected through new development should reflect a locally identified need. This can help to avoid deficiencies in different types of open space, and to ensure that open spaces are being effectively used. Watford's open spaces are not evenly distributed across the borough. Some communities are deficient in open space and require improved access to these recreational areas, whereas in some neighbourhoods there may be opportunities where alternative open space and ancillary uses could be considered if there is a demonstrated need.

(3) Policy NE9.6: Protecting Open Space

Open space and ancillary facilities used for leisure and recreation will be protected, unless an up to date assessment demonstrates the space is surplus to need. For an open space or an ancillary facility to be considered surplus to requirements, the following must be demonstrated:

  1. An assessment has been undertaken that has clearly shown the open space, buildings or land to be surplus to requirements, having regard to the Council's most recent evidence base; and
  2. The open space is not needed for alternative open space uses; or
  3. An equivalent or better facility in terms of quality and quantity is to be provided in a more suitable location that meets the needs of the local community.

Development proposals for alternative open space uses will be supported where an up-to-date assessment clearly shows the benefits outweigh the loss.

The absence of identification of an open space on the Policies Map does not imply that development is appropriate.

(1) Providing new open space

9.28 As new development comes forward, there will be opportunities to create new communal open space on site. While some level of private amenity space will be expected (Policy HO3.11 Private and Communal Outdoor Amenity Space'), larger developments can also help to provide communal sports and recreational facilities, such as:

  • Parks, public gardens and recreational grounds;
  • Amenity green spaces;
  • Equipped play space;
  • Natural and semi-natural green spaces;
  • Outdoor sports facilities;
  • Churchyards and cemeteries; and
  • Allotments.

9.29 The different types of open space have been defined in the Green Spaces Strategy. The strategy sets out where these different facilities are located in the borough and appropriate catchment distances for each type of open space. Where a development does not lie within the catchment distance of a type of open space, it will be imperative that this is provided on site to reverse the deficiency.

9.30 In circumstances where on site open space provision is not practical, feasible or would not benefit the scheme, a financial contribution may be acceptable with the agreement of the local planning authority. This contribution will be secured through planning conditions. In these cases, some level of communal open space and landscaping should be provided on site.

9.31 For outdoor sports facilities, it is not expected that provision will generally be possible on site. For areas deficient in outdoor sports facilities, contributions will be sought through the Playing Pitch Calculator, in line with the Playing Pitch Strategy (2020). Therefore, new residential developments will be required to provide open space, such as amenity and equipped play space on site, or where practical, other forms of open space such as allotments or semi-natural areas, where opportunities exist to enhance the green infrastructure network and support local residents.

9.32 The design of new play areas and other formal open spaces should take account of good practice provided in Sport England's 'Active Design' guidance and any subsequent replacements.

(1) Policy NE9.7: Providing New Open Space

New developments proposals will be supported where they contribute to the provision, enhancement and maintenance of open space, either by means of on-site provision or though developer contributions.

Where there is an identified deficiency, as set out in an up-to-date open space needs assessment, development proposals of ten dwellings or more will be required to provide publicly accessible open space on site. Provision should reflect the type of open space required in the area through accessibility, quality and value.

Proposals that include new open space should be accompanied by a site management plan, in agreement with the Council, which sets out a proactive approach to the long term maintenance of the site.

(2) Biodiversity

9.33 Despite being a largely urban borough, Watford is rich in biodiversity. Watford contains a number of Local Nature Reserves and Local Wildlife Sites and is home to European Protected Species such as great crested newts and pipistrelle bats. Other locally important but non-designated wildlife sites also make a significant contribution towards biodiversity in the area.

9.34 The sustained loss of green infrastructure and the breaking up of its networks can have a damaging effect on ecosystems in Watford. Inappropriate development could threaten the future of different species through habitat fragmentation and the loss of habitats. Given development pressures, it will important to ensure that Watford's biodiversity is protected and enhanced. Development proposals should contribute positively to ecosystems in Watford through the delivery of net gains in biodiversity.

9.35 New development should support the creation of new wildlife habitats, which can be integrated into the layout and design of sites, as well as offsite where this cannot otherwise be achieved. Traditionally, this would include habitats incorporated as part of open space, such as water courses, vegetation and planting. However, some contemporary schemes have evolved to include green/brown roofs, living walls and roof and rain gardens, which support biodiversity, amongst other benefits. Where appropriate, smaller alterations can include providing integrated bat or bird boxes within the fabric of new buildings, or hedgehog highways to make gardens more permeable.

9.36 The Council will take a hierarchical approach to assessing proposals, as set out in national guidance. Compensatory measures will only be considered when no other measures are demonstrated to be feasible as set out in the mitigation hierarchy (Figure 9.4). In such an instance, Biodiversity Offset Agreements must be secured through Section 106 Agreements. The process for this will be set out in a Supplementary Planning Document.
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(2) Policy NE9.8: Biodiversity

Development proposals should apply the mitigation hierarchy to avoid or mitigate harmful effects on biodiversity. Protected sites of international, national and local importance will be protected from inappropriate development based on the importance of the designation.

New development should seek to achieve an overall net gain in biodiversity. This must be measured through the use of the latest Natural England biodiversity metric. The biodiversity metric should demonstrate an improvement in biodiversity units of 10% or more from the existing baseline value of the site.

Development should apply the mitigation hierarchy to avoid or mitigate harmful effects on biodiversity. Mitigation and compensation measures must offset any losses to achieve a measurable net gain for biodiversity. Where it is not possible to avoid or mitigate all impacts on site, an offsite Biodiversity Offset Agreement should be submitted.

Where there is a reasonable likelihood of the presence of a protected species or its habitat, applications must be supported by an ecological survey. If present, the proposal must mitigate or compensate appropriately in accordance with the legislation that protects them.

To take part in these consultations, you will first need to register as a user by clicking on the link at the top right of this page. Once you have registered, select a document, then comments can be given by clicking on the pen icon and writing in the form that appears. For further assistance please read our help guide.
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