The HS2 route in the Chilterns and the Colne Valley High Speed Two (HS2) N North Portal Chesham Rd Intervention Shaft Little Missenden Vent Shaft Amersham Vent Shaft In design development In design development In design development In design development is the new high speed Next event Next event This event Next event North Portal – Design Event, Chesham Road Intervention Shaft - Little Missenden ‘You Said, Amersham – ‘You Said, We Did’, railway for Britain. Summer 2021 Design event, Summer 2021 We Did’, May 2021 Summer 2021 Chesham What we are doing Great Missenden Align are working on behalf of HS2 Ltd HERTFORDSHIRE Chilterns Area to build 22 kilometres of the high speed of Outstanding Amersham rail line, running between the Colne Natural Beauty Valley and the Chilterns. It includes the 3.4 kilometre long Colne Valley High Viaduct and the Chiltern tunnel with Chalfont Wycombe four ventilation (vent) shafts to regulate St Giles airflow, one intervention shaft and the shaft headhouses which contain Chalfont St Peter electrical equipment. GREATER LONDON Our main works programme is now Colne Valley underway and we are holding regular Regional Park BUCKINGHAMSHIRE information events to share details Old Oak Euston on the progress of the designs, seek Common Station views and respond to feedback. Due to Station Covid-19 we have postponed all public face-to-face engagement events and Chalfont St Giles Vent Shaft Chalfont St Peter Vent Shaft Colne Valley Viaduct South Portal/Western Valley slopes meetings, but we will continue to find Next event Next event Next event Next event Chalfont St Giles Vent Shaft - Chalfont St Peter Vent Shaft - Colne Valley Viaduct Western Valley Slopes new ways to involve the community. ‘Construction Update, ‘Construction Update, ‘Construction update, ‘Construction update, Summer 2021 Summer 2021 Summer 2021 Summer 2021 Introduction Welcome to our ‘You HS2 route through the Chilterns Said, We Did’ event for Hyde Heath the Little Missenden vent shaft A413 Chesham Road Keepers Lane Intervention Shaft Little Missenden In November 2020 we held an event to Vent Shaft share our plans for the Little Missenden vent shaft, the construction processes, Little Missenden Mop End Lane traffic management plans and the early Vent Shaft plans for the design of the headhouse. Now we would like to: Amersham Vent Shaft Chalfont St Giles N HS2 Tunnel • Show you the feedback that we have Vent Shaft received during design development, which has influenced our approach Chalfont St Peter The Little Missenden vent shaft will • Share the final designs we will be Vent Shaft provide air ventilation and access for seeking consent on from your local emergency services. It is located off the authority A413 to the east of Little Missenden. • Provide information on the construction of the vent shaft and headhouse • Show you how we plan to reduce the impact of our work on residents. N 0 1 2 4km Public feedback In November 2020, we held a public engagement event and you gave us feedback on four topics about our design. We asked you to rank our objectives in order of priority and provide comments. Your ranking of these objectives are shown below: Landscape Ecology Design of the headhouse Construction • Respond to the character of the site • Protect existing wildlife species on the • Design a structure that blends into the • Return the wider construction site to and surrounding landscape site during construction landscape how it was before construction started • Use existing trees, hedgerows and new • Keep as many existing trees and • Reduce visibility of buildings • Reduce noise and vibration on the planting to conceal structures as far as hedgerows as possible • Keep the overall footprint (area) of the construction site possible • Restore the area using planting or compound as small as possible • Reduce HGV movements • Replace lost trees which must seeding of native and indigenous • Maintain a familiar scale and form to • Let people know when noisy works are be removed during construction, species local farm buildings occurring and keep residents regularly wherever possible • Create habitats that support as many • Reduce the operational impact of the updated • Consider the long term management species as possible (biodiverse) proposed structure • Minimise any visible impact of of the site and appearance of the new • Create habitats that are typical of construction landscape • Choose materials and detailing inspired the area but rare and declining – for by the local landscape • Minimise carbon footprint and reduce • Consider ways to enhance public example, chalk grassland the noise and air pollution across experience in places where people get • Create habitats that are integrated with construction fleet close to the site (for example from the the surrounding area diverted public footpath) Landscape You said: “Respond to the character of the site and surrounding landscape” Landscape proposals Keeper’s Wood Public “Use existing trees, hedgerows and new planting to conceal Retained vegetation screens footpath structures as far as possible” views from the A413 We did: A413 Section A-A Maintain landscape character Screen buildings and compound The landscape will be shaped to We will retain as much of the existing integrate with the profile of the valley vegetation along the A413 as possible, 6 edge, whilst woodland and shrub whilst planting substantial areas of native 2 planting and chalk grasslands will tree and shrub species to screen the 4 reinforce the rural setting. buildings and structures. Key A N 1 Proposed woodland edge and 2 6 scrub planting areas 7 5 4 2 Chalk grassland 1 3 Temporary water body 5 7 4 Agricultural style fencing 3 1 compliments rural character A413 of the site 1 A 3 1 5 Profile of chalk valley retained Key A413 6 Reinstatement of public footpath Existing trees retained Proposed trees and vegetation 7 Site access from A413 Public footpath reinstatement Landscape plan Illustrative view of the site Ecology You said: “Consider the long-term management of site” “Restore the area using planting or seeding of native and indigenous species” 5 We did: Propose new contextual habitats and prepare management plans 6 We will create connected habitats using 1 c native plants and seeds to enhance the biodiversity value of the site. HS2 will undertake long-term management of land in its ownership guided by b b a Habitat Management Plan for the lifespan of HS2. Our plans include: Creation of calcareous grassland habitat 1 3 1 2 reflective of Chilterns grassland Calcareous grassland (target habitat) 2 Retention and protection of existing habitat 6 a connectivity New woodland edge and scrub planting used 2 3 Subsoil cap A413 4 to connect habitats, encouraging animal 3 foraging and movement Stones, branches, logs 4 Incorporation of habitat features such as: Gravel drainage layer a Hibernaculum Entrance points Key b Reptile Egg Laying Heaps Existing trees retained c Reptile and Invertebrate / Basking Bank Proposed trees and vegetation 5 Protection of Keeper’s Wood (ancient a Public footpath reinstatement woodland) - this will not be impacted by HS2 and is outside our site boundary Section - Typical hibernaculum Habitat creation proposals Headhouse design You said: “The vent shaft should blend into the Chilterns landscape as far as Gently raised land possible to minimise the impact on our countryside” Agricultural courtyard arrangement We did: Agricultural fence and gate Arrange buildings in an agricultural compound layout Headhouse compound fence The arrangement of the buildings is 1 Central courtyard for access and based on an agricultural courtyard manoeuvring Above Ground Permanent access road layout, with the overall footprint of the 2 Doors accessed from the courtyard Infiltration basin compound kept to a minimum. 3 Primary elevation of each building faces into courtyard Existing trees retained 4 Ancillary structures kept low to reduce visual A413 clutter 3 2 Basement box 2 Below Ground 1 3 Ventilation shaft 4 3 North and South running tunnels N 3D diagram - Building arrangement 3D diagram - Overall site arrangement Headhouse design You said: “The proposed buildings must be sensitive to the environment and look to blend in with existing houses, farm dwellings“ We did: Took inspiration from the local historic and industrial agricultural buildings Pitched roofs wrap around the buildings, recessed and treated in a different creating simple agricultural barn forms. material, providing greater articulation to Buildings are orientated to reduce their the buildings. The louvred screen breaks perceived scale from key viewpoints. up the overall form and hides visual Door and ventilation openings are clutter associated with plant equipment. 3D diagram - Form and scale Visualisation - Aerial view 3D diagram - Louvred openings Headhouse design View looking west from lane through the trees Key Plan - Location of view point Visualisation - View from east (Year 1) Visualisation - View from east of site looking west (Year 15) Headhouse design You said: “Can you reflect local building materials?” We did: Use a simple palette of robust materials that blend in The zinc, painted steel and engineering The building colour and detail has been brick will be durable and designed to designed to blend into the landscape, age gracefully over time without losing using a simple palette of materials robustness and quality. Dark, neutral inspired by local agricultural and colours will ensure the buildings are industrial buildings. concealed as much as possible.