Hong Kong International Airport (HKIA) has launched the multi-year regulatory approval process needed for a major expansion.

Built on a 1,250-hectare, man-made island, HKIA was considered an engineering marvel when it was completed in 1998. Now efforts are under way to add another 650 hectares to the north side of the island to accommodate a third parallel runway.

Operations at HKIA will outgrow the facility’s current two-runway layout by 2020, according to the airport authority. Demand originally was expected to reach 380,000 aircraft movements a year by 2040, but flights have increased much faster, and latest estimates expect demand to rise to 602,000 flights per year by 2030.

A third runway with associated taxiways, aprons, passenger concourses and extensions to existing facilities is expected to cost up to HK$136.2 billion ($17.5 billion) and would open in 2023.

The airport recently began the environmental review process, one of the major regulatory hurdles it must overcome. This week it submitted a project profile to Hong Kong’s Environmental Protection Department, giving basic details of the development plans and outlining potential environmental effects.

The public has 14 days to comment on the project profile, after which the director of environmental protection will set the scope of the main environmental impact assessment (EIA) study.

The EIA process is expected to take two years.

Acquiring the environmental permit, developing detailed plans and gaining final government sign-off on the project should be completed by 2015. Only then can the construction phase begin, and this will likely take eight years.

Cathay Pacific is an enthusiastic supporter of the third runway, which it says is of “critical importance” to the Hong Kong economy. The project is the “only viable option to ensure the long-term competitiveness” of both the airport and Hong Kong itself, says the airline.

The airport authority in 2011 outlined two options for HKIA’s future:­ staying with two runways or adding a third. In March 2012, the government of the Hong Kong Special Administrative Region authorized exploring the third-runway option, opening the way for HKIA to seek the environmental and other regulatory approvals required.

Other developments also are under way at HKIA. A midfield passenger concourse with 20 additional aircraft parking stands will cost HK$10.2 billion and is scheduled to be completed in 2015. Meanwhile, Cathay says it is investing HK$5.7 billion in a cargo terminal that is due to open in early 2013. But the third runway will undoubtedly have the largest long-term impact.