A consultation exercise launched this week provides details of a proposed expansion that includes construction of a third runway and diverting the M25.
The airport is hoping to increase the number of flights by more than 50 per cent but has faced fierce opposition from local residents and environmental campaigners who say the proposed expansion would result in unacceptable increases in noise and pollution.
Heathrow said the consultation exercise will inform a development consent order (DCO) application to be submitted to the Planning Inspectorate in 2020. If consent is granted, the airport said it hopes the third runway will open in 2026.
The airport said the DCO application will seek to lift the current cap of 480,000 air transport movements a year, which was imposed when planning permission was granted for Terminal 5 in 2001. Heathrow said it wants to increase the cap by 260,000.
Diversion of the M25 near the airport, which is expected to involve a new carriageway and tunnel built up to 150m to the west of the existing road, will be the subject of a separate DCO application.
Mitigation measures proposed within the current consultation include a ‘noise envelope’, described as "a set of legally binding and enforceable limits and controls to manage noise", which will be developed "with local communities and other stakeholders".
Heathrow said expansion would allow restrictions to be imposed on night time operations to ensure all nearby communities receive at least seven hours respite between the hours of 10pm and 7am.
The consultation states that expansion will only take place if it can be shown that it will not result in any changes to air quality that would cause an air quality-compliant zone to be non-compliant or delay the date that any currently underperforming areas are expected to achieve compliance.
Heathrow has also proposed a 20km "green loop" around the airport, comprised of footpaths and cycleways that "connects open spaces, communities and functions as a wildlife corridor in places".
Revised boundaries will include alterations to local rivers to the west and south to create a "natural edge" between the airport and the M25, the document says.
An earth embankment "may combine noise mitigation and visual screening" to the north. The southern boundary will include hotels, offices and cargo facilities, the consultation states.
Heathrow also said it is proposing a community fund for "community activities, health, transport, or the environment", employment initiatives, and "additional or ongoing mitigation measures, particularly where it is not possible to identify or quantify the measures necessary at the time of submitting the DCO application or when the DCO is granted consent".
The consultation will run for 12 weeks until 13 September 2019.
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."
Government support for a third runway at Heathrow was established in principle by the Airports National Policy Statement (NPS), which was adopted in June 2018 and sets out a number of requirements any expansion will be expected to meet with regards to issues including air quality and noise pollution.
A legal challenge to the NPS, made by five local authorities, Greenpeace and the mayor of London, was dismissed by the High Court last month.