When Hong Kong International Airport (HKIA) set out to build a new runway and associated facilities for the three-runway system operation, engineers had to carefully navigate a challenge hidden beneath the surrounding waters. The project involved 650 hectares (1,606 acres) of reclaimed land adjacent to the existing airport, an area equivalent to about 34 Victoria Parks or 900 standard football pitches. More significantly, some 40 per cent of it sat directly above decades-old mud pits storing...