Align JV is utilizing chalk excavated from the Excessive Pace 2 Chiltern tunnels to create grassland habitats within the Chiltern Hills.
The environmental venture on Excessive Pace 2’s (HS2’s) largest building website reached the 1M.m3 milestone this week. The chalk has been laid out across the south portal of the tunnels.
In complete, round 2.6M.m3 of chalk might be excavated throughout the building of the 16m lengthy tunnels. It will likely be used to panorama the location, which is about to change into a 127ha wildlife haven.
It will embody the biggest areas of chalk grassland within the Chiltern Hills.
The plans have been developed by HS2’s most important works contractor, Align, a three way partnership fashioned of Bouygues Travaux Publics, Sir Robert McAlpine and Volker Fitzpatrick. It’s engaged on the venture with its design companions Jacobs, Rendel-Ingerop and LDA Design, which kind Align D.
HS2 Ltd’s surroundings director Peter Miller mentioned: “The south portal venture is likely one of the most essential elements of our Inexperienced Hall programme to determine higher related, sustainable and biodiverse landscapes alongside the route of the brand new railway and can contribute considerably to HS2’s carbon discount goal.”
The 2 tunnel boring machines (TBMs) – named Florence and Cecilia – engaged on the Chiltern tunnels are presently round 6.4km into their journey. Align not too long ago additionally accomplished the primary tunnel cross passage underneath the Chilterns.
The fabric the TBMs excavate is blended with water to kind a slurry earlier than being pumped out of the tunnel.
It’s then processed at a slurry therapy plant on the south portal website the place the flint is eliminated and water extracted. This leaves a chalk cake which is then laid out on website, along with recycled concrete and aggregates from building works, to be able to create a naturalistic panorama with all of the short-term building buildings eliminated.
Align D design director Chris Chantler mentioned: “This progressive, multi-discipline venture is offering a singular alternative to create an enormous expanse of recent grassland utilizing chalk being excavated from the Chiltern tunnels.
“With the primary million cubic metres of chalk having already been positioned to create the grassland, we’re properly on the best way to making a panorama which might be each wealthy in variety and a spot for folks to discover and join with the pure surroundings.”
Chalk grassland – a kind of calcareous grassland – is a habitat of worldwide conservation significance primarily discovered on limestone and chalk downlands of south east England and the Isle of Wight.
The skinny soil is lime wealthy however low in vitamins, and it holds little water and drains properly. In keeping with HS2 Ltd, these circumstances encourage an enormous number of smaller herbs and wildflowers and greater than 40 plant species could be present in 1m2 of grassland, together with a number of the UK’s rarest orchids in addition to various invertebrate populations. Solely 700ha of chalk grassland exist throughout the entire of the Chilterns Space of Excellent Pure Magnificence.
On the Chilterns website, 90ha of chalk grassland might be seeded into re-profiled soil layers. It will sit alongside new areas of woodland, wooden pasture and wetlands, together with nearly 65,000 timber and shrubs of 32 species and almost 3.5km of recent hedgerows.
Subject trials are in preparation forward of ultimate seeding, and planting of timber and shrubs in 2025.
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