2.2 Ground Improvement
The soft clay beneath of west runway and east runway system along with main apron was improved by the prefabricated vertical drain (PVD) preloading method started in the late 1990s. The site was first cleared and leveled before the ground improvement work. Existing canals were backfilled by silty sand (with fine content of less than 25%) and clayey soil for the upper 1.5 m (Figure 2).