Integration of the HS2 rail line with the Western Valley slopes. Credit: HS2 HS2 has announced a new "ambitious" scheme designed to enhance the environment near two major tunnels it is constructing. Bosses of the multibillion pound high speed railway say they want to create 127 hectares of new chalk grassland, woodland, wood pasture and wetland habitats. Labelled the Colne Valley Western Slopes project, HS2 says the scheme is the "biggest single landscape and habitat creation project within HS2’s Green Corridor programme". The plans near West Hyde on the Hertfordshire and Buckinghamshire border includes the planting of almost 65,000 trees and shrubs of 32 species, with nearly 3.5km of new hedgerows.