The suggestion to move the centre to Buckinghamshire from its current home in Denham was put forward a year ago, but the Department for Transport (DfT) announced on Thursday (September 20) it had been abandoned.
In the wake of the decision, HOAC management has written to the Transport Secretary Chris Grayling to say the centre will close before HS2 work starts if the decision is not reversed.
The letter, signed by chair of the Colne Valley Youth and Community Association, Karen Smaggasgale, says: “Since the first visit by HS2 to HOAC's site we have been clear that HOAC cannot co-exist with HS2.
“The disruption to the centre during construction and during operation due to adverse noise effects and the visual impacts the construction work and subsequent viaduct will render HOAC's operations unviable.
“If the decision remains not to relocate HOAC then the centre will close before any operation starts.”
HOAC was set up as a Youth Educational Charity in 1992 in partnership with Hillingdon Council and provides outdoors activities for schools and groups.
The 45-acre lake is used for kayaking, canoeing, sailing and windsurfing, while land activities include archery, caving, fencing and karting.
Two key decisions on the future of HOAC were made by the DfT on Thursday – the building of a viaduct, rather than a tunnel through the Colne Valley was confirmed as well as the decision not to relocate the outdoor centre.
'HOAC cannot co-exist with HS2'
A DfT spokesperson said: “Following an independent review, the Transport Secretary has agreed with HS2 Commons Select Committee that the plan for a viaduct, rather than a tunnel, in the Colne Valley is best value for money.
“Also, despite our very best efforts to relocate the Hillingdon Outdoor Activities Centre to Denham Quarry, it has now become clear that escalating costs mean it won't be a sustainable long term option.”
The company behind the rail link to Birmingham and the north of England, HS2 Ltd, said last October HOAC could be relocated to Denham Quarry near Uxbridge by 2018.
According to the DfT, the anticipated cost of relocating HOAC had more than doubled to £55million because of construction, land costs and compensation arrangements.
Instead the government has suggested an alternative plan to keep HOAC at its current site, but this has not been welcomed.
Chair of Hillingdon Against HS2, Keri Brennan , said: “It's disgusting. They let people believe there was going to be this alternative.
“They're saying we can run an activity centre in the middle of a building site.”
The letter from HOAC to Chris Grayling goes on to say: “HOAC is currently in an ideal location offering peace and serenity so close to major areas of population, a building site and subsequent railway will remove the key attributes that makes the centre work for all of its users.”
Preparing to terminate contracts
HOAC have requested a firm start date for HS2 work so they can "make provision to terminate staff contracts, cancel future group bookings and inform members and users so they can make alternative arrangements."
The DfT spokesperson added: “Despite being one of the largest construction projects in Europe, the government and HS2 Ltd are committed to making sure HS2 is an environmentally responsible transport scheme and that we minimise the effects on the countryside and communities as much as possible.”