First look at HS2's approved 'ambitious' plans to improve environment surrounding Chiltern tunnels

HS2 has received permission to use material excavated from the Chiltern tunnels to create new grassland by the affected area

Plans have been approved to create new chalk grassland, woodland, wood pasture and wetland habitats on what is currently an HS2 construction site.

A HS2 spokesperson described the plans: "As the biggest single landscape and habitat creation project within HS2’s green corridor programme".

The project involves planting 5,000 trees and shrubs of 32 species, and 3.5km of new hedgerows, HS2 says.

The Colne Valley is the area HS2 plans to transform using chalk grassland. Which is a type of calcareous grassland, mainly found on limestone and chalk valleys of south-east England and the Isle of Wight.

A HS2 spokesperson described the effects of the chalk grassland, saying: "Lime-rich, but low in nutrients, the thin soil holds little water and heats up quickly. These conditions encourage a huge variety of smaller herbs and wildflowers and over 40 species can be found in one square metre of grassland, including some of the UK’s rarest orchids and invertebrates. Only 700 hectares of chalk grassland exist across the whole of the Chilterns AONB (Area of Natural Outstanding Beauty) .

"Ninety hectares of chalk grassland will be seeded into re-profiled soil layers using the nutrient poor subsoils on the site and mixing these soils with chalk from the tunnelling and recycled concrete and aggregates from construction works. The design of these soil profiles will be completed through collaboration with Cranfield University and Tim O’Hare Associates in an innovative research study that will use the results from both laboratory and on-site trialling of the soil layers.

"This will sit alongside new areas of woodland, wood pasture and wetlands, including almost 65,000 trees and shrubs of 32 species and nearly 3.5km of new hedgerows. Around 4.5km of new footpath, cycling and horse-riding routes will give the public areas to large parts of the site, which sits between the Colne Valley Regional Park and the Chilterns AONB."

HS2's environment director Peter Miller commented: “The Western Valley Slopes project is one of the most important parts of our Green Corridor programme to establish better connected, sustainable and biodiverse landscapes along the route of the new railway and will contribute substantially to HS2’s carbon reduction target.

“It demonstrates HS2’s approach to addressing many of the complex issues surrounding climate change and which are central to protecting our environment, and is a great example of how good design and planning can mitigate the effects of climate change. A huge amount of work has gone into the planning for this ambitious project and it’s great that that’s been recognised in the schedule 17 approval.”

The plans were approved by Three Rivers District Council (which covers more than 99% of the site) and Bucks Council under Schedule 17 of the HS2 Act 2017.

HS2 has previously come under fire for its plans in Bucks and the impact it would have on the environment as a whole, both from the public and the council.

The 10-mile long Chiltern tunnel is due to be completed in 2024. The planting of trees and shrubs is scheduled for 2025.