Meeting Biodiversity Net Gain (BNG) requirements on Northern Gateway’s complex, multi-authority development

Complexity of stakeholders

The project is led by the Northern Gateway Development Vehicle (NGDV), which is a joint venture between two major land developers, Russell LDP and Harworth Group. The site spans two separate local councils in Greater Manchester (Rochdale and Bury). That means two separate local planning authorities (LPAs) as well as the two developers, collaborating with our ecologists, arboriculturists and landscape architects. Add to that all the other disciplines within the wider project team, such as heritage, drainage, and so on. That’s a lot of moving parts.

A worst-case scenario

We initially assessed the outline application on a worst-case BNG scenario. In simple terms, we assumed the majority of the site would be developed; other than areas of retained habitats, of particular note, the Whittle Brook Corridor.

That assumption led to a significant projected drop in the site’s net BNG. However, it was a deliberate and justified approach. By testing the scheme under the most demanding scenario, we’ve built in maximum flexibility for future developers. That flexibility will be essential for delivering a commercial scheme that is likely to come forward in phases over a long period.

Nick Bell, our Senior Ecology Consultant, explains how: “It’s unusual because we’ve assessed it on a worst-case basis, assuming a much larger development footprint than what will ultimately be built out. It was essential that for the outline application, maximum flexibility for the size, location and orientation of the units was assessed. Knowing that as the scheme progresses through planning, and further detail comes forward, BNG can be refined and the overall BNG deficit reduced as more green infrastructure is incorporated into the scheme design on a plot-by-plot basis.”

BNG at scale

Mandatory BNG is a relatively new regulatory landscape. At this scale, the approach created some initial nervousness surrounding the BNG deficit. Commercial schemes of this nature (large warehouse units) generally struggle to achieve net gains purely on-site compared to residential or solar projects, where BNG offsetting can occur more easily within the redline boundary. It was accepted from the project’s inception that a development this big would likely require off-site BNG, but would also need careful planning to deliver both on-site habitat creation and appropriate off-site BNG units.

Nick expands: “Although the BNG baseline value of the site was relatively low (90% of the baseline habitats comprised species-poor agricultural grassland), the scale of the grassland loss resulted in a large on-site BNG deficit”.

Off-site BNG (but only across the road)

While it was clear that much of the mitigation would need to take place off-site, green space will still be integrated into later phases of the development, as Nick points out: “In addition to the retained habitats, such as the Whittle Brook Wetland Habitat Corridor, when it comes to detailed design, habitats such as hedgerows, watercourses and woodland will be retained and created in the green infrastructure landscaping around the warehouses.”

For the off-site BNG, however, there’s an ideal solution just over the road. The owners of the land, Wilton Estates, also own neighbouring land and have given permission for its use for off-site BNG. This is an ideal solution. Not only will the BNG loss be lower than currently proposed, but the off-site BNG mitigation will occur within the same districts (Bury and Rochdale) as the application land, and therefore keep biodiversity net gains within the local area.

“Not only is this a benefit for BNG, it helps in terms of the protected species that are present at the application site. For example, for birds, specific habitats are being created both on-site and within neighbouring land to maintain and enhance the suitability of habitat for such species,” says Nick.