This paper presents a case study for soil improvement using a combined vacuum and fill sur-charge preloading method for the 3rd runway of the Suvarnabhumi International Airport in Bangkok, Thailand. Prefabricated vertical drains of 10 m long was used. The preloading consisted of an average of 86 kPa of vacuum pressure plus a 22 kPa of fill sur-charge due to the granular fill and drainage layer. The vacuum preloading system adopted is described. Monitored settlements and pore water pressures are presented. The average ground settled monitored is around 70 cm and the average degree of consolidation as estimated using settlement data is higher than 90%. Degree of consolidation is also calculated using pores water pressure distribution monitored along the depth which gave a good verification of the degree of consolidation achieved.