Rivers and roads could be re-routed under a “masterplan” to expand Heathrow Airport.

The M25 would be realigned under a tunnel, rivers diverted and local roads rerouted within the next decade as part of the first phase of expansion of the west London hub.

A four-phase plan was released as a 12-week consultation opened on Tuesday to allow people to give feedback on the airport’s proposals, which include the completion of a third runway by around 2026.

Expansion of the airport has been the subject of debate for many years.

A stage-by-stage map of how plans will progress until around 2050 has been released, showing the development of hotels, offices and parking in the area, as well as marking out green spaces.

The public will be able to have their say on plans to manage the environmental impacts of expansion, including a proposed Heathrow Ultra Low Emissions Zone, Heathrow Vehicle Access Charge and a proposed six-and-a-half-hour ban on scheduled night flights.

Among developments in the first phase of the plan are the re-routing of a 12-lane section of the M25 into a tunnel under the new runway, diverting of river corridors and creation of new drainage and pollution control areas, and realignment of the Colnbrook Railhead freight line.

New locations have also been marked out for places such as Harmondsworth Primary School and Heathrow Special Needs Centre, which will be moved within the first phase.

Plans for mitigating the effects of expansion, include property compensation, namely a home loss payment calculated at 25% of the unaffected open market value, a £700 million noise insulation policy, and a community fund.

Emma Gilthorpe, Heathrow’s executive director for expansion, said: “Expansion must not come at any cost.

“That is why we have been working with partners at the airport, in local communities and in Government to ensure our plans show how we can grow sustainably and responsibly – with environmental considerations at the heart of expansion.

“This consultation is an opportunity for people to have their say on our preferred masterplan, so it’s really important that as many people as possible take part. We look forward to hearing your views.”

The plans revealed in this consultation incorporate the feedback gathered from the airport’s first public consultation on expansion in 2018, and the Airspace and Future Operations Consultation held earlier this year, “as well as from continuous engagement with local communities, local authorities, airlines, environmental stakeholders and other interested parties”, the airport said.

Responses to this consultation will inform Heathrow’s application for a Development Consent Order (DCO) – the planning consent required for the project – which is expected to be submitted to the Transport Secretary next year.

Paul Beckford from the No 3rd Runway Coalition, a campaign organisation opposing the expansion, said: “Heathrow will claim this is the largest consultation ever and that may well be right.

“However, this simply reflects the sheer scale of the impact that their expansion plans will have on local communities.”

Mr Beckford said that “incredibly” it appears Heathrow wants to “spread the misery of their expansion plans over a 30-year period, inflicting the blight of construction and the resultant increases in air and noise pollution on communities across London for decades”.

He added: “Every community across London and the Home Counties will experience the impacts to these proposals and we urge anyone concerned about the expansion to state their objections loudly and clearly in their responses to the consultation."