Biodiversity Net Gain, guidance for developers and ecological consultants

Important issues to consider when planning how to meet your BNG requirements.

Mitigation hierarchy

While the introduction of a metric that generates numerical values to quantify losses and gains of habitats is one of the most striking aspects of Biodiversity Net Gain, the metric is only a tool to help to estimate the value of what is being proposed.

The purpose of Biodiversity Net Gain is to require development to have a positive impact on biodiversity overall through the creation and enhancement of habitats, and so at every stage of the process it is essential that ecological principles are being followed and the process is being considered in terms of how to achieve best outcomes for nature rather than just best numbers in the metric. 

Importantly, the mitigation hierarchy set out in paragraph 186a of the National Planning Policy Framework (NPPF), (when determining planning applications, local planning authorities should apply the following principles: (a) if significant harm to biodiversity resulting from a development cannot be avoided (through locating on an alternative site with less harmful impacts), adequately mitigated, or, as a last resort, compensated for, then planning permission should be refused), remains paramount - harmful impacts must first be avoided. Where they are unavoidable, they must be adequately mitigated, with compensation being a last resort.

Enhancement should then be secured over and above that. Accordingly, the net gain process can be seen to apply right at the end of that process - to the compensatory and enhancement stages. It does not remove the need to seek to avoid impacts as the first priority. 

To help ensure that good ecological outcomes are secured through the Biodiversity Net Gain process, a series of nine metric principles are set out in section 3 of the metric user guide (opens new window), in addition to the four metric rules that must be adhered to in all circumstances. The principles exist to ensure that expert ecological advice and established ecological principles are always used throughout the BNG process.

A guide called Biodiversity Net Gain: Good Practice Principles for Development (opens new window) has also been produced by Chartered Institute of Ecology and Environmental Management (CIEEM), Institute of Environmental Management and Assessment (IEMA) and Construction Industry Research and Information Association (CIRIA), which provides extensive advice to ensure that best ecological outcomes can be secured through the BNG process. 

The use of the biodiversity metric does not override existing biodiversity protections, statutory obligations, policy requirements, the ecological mitigation hierarchy or any other requirements.

These are interim arrangements for the strategic significance section of the metric until the South of Tyne and Wear Local Nature Recovery Strategy is published

Strategic significance describes the local significance of a habitat based on its location and the habitat type.

All habitat parcels (both baseline and post-development) must be assigned a strategic significance score; it should be considered separately for each individual habitat parcel in the metric and not on a site-wide basis. 

On an interim basis, until the South of Tyne and Wear Local Nature Recovery Strategy (LNRS) is published, strategic significance categories should be based on:

• Mapping of the Gateshead Wildlife Corridors as shown on the Policies Map 
• Habitats listed as Priority Habitats for Durham Vice County 66 in Appendix 16 of Making Spaces for Growing Places (MSGP) Local Plan Document (PDF, 8 MB) for Gateshead (Gateshead Council February 2021).

High:

Where the project delivers a local priority habitat within a Wildlife Corridor:

• Record the strategic significance as low in the baseline tab
• Record strategic significance as high in post-development tab 
• Record the documents used in the user comments

Medium:

Cannot be applied given that the habitats and locations to be considered have been specified by the local planning authority (as above).(See table 7 of Statutory Metric User Guidelines)

Low:

Where the definitions for high strategic significance are not met. Even if your project is within a Wildlife Corridor, if it does not deliver a local priority habitat you should:

• Record strategic significance as low in the baseline
• Record strategic significance as low in in post-intervention sheets

Provision of BNG on the development site

In principle, the development site itself is the preferred location for created or enhanced habitats that will satisfy the BNG requirement, so that there isn't a spatial separation between where habitats are being lost and where they are being established, and to ensure that local communities benefit from a nature-rich environment.

However, there are significant issues to be considered when determining whether this is realistic, especially on residential sites. Inevitably open space is going to be used by local residents for a range of uses such as informal play and exercise, including dog-walking.

This imposes some extra considerations on top of the normal considerations such as soil nutrient status in determining what habitats could realistically be sustained and managed, and what condition could realistically be achieved for those habitats. 

Size / extent, disturbance levels and lighting must also be considered when determining whether habitat types/conditions can be deemed realistically representative of targeted habitats.

Once they have been created, the habitats will need to be managed for a 30-year period, during which a monitoring process will be used for significant on site habitats, to determine if the required gains are being achieved and to identify remedial measures if not. It is therefore in everyone's interests to ensure that BNG proposals are realistic and achievable.

Meeting the BNG requirement through the purchase of biodiversity units

Habitat Banks, areas of land where habitat is created or enhanced to sell the resulting biodiversity units to developers,  may be established in Gateshead. In order to do this, landowners will need to conclude legal agreements with the Council and then register the sites with Natural England.

The Council intends to maintain a list of registered sites in Gateshead so that it is straightforward for developers to find local providers.

Meeting the BNG requirement on other land owned by the developer

If a developer intends to satisfy their BNG requirements on land that they own outside of the red-line boundary of their development site, they will need to sign a S.106 Agreement with Gateshead Council and then register the offsite area with Natural England, following the same process as for Habitat Banks.

For further information about BNG visit the Planning Advisory Service (PAS) (opens new window).

To discuss Gateshead Council's approach to biodiversity net gain, including delivery of offsite gains, please contact planning@gateshead.gov.uk