The marine clay underlying the second runway, taxiways and turnoffs of the new Changi International Airport was consolidated using geodrains and surcharge. A pilot test was carried out to enable the selection of the most suitable method of soil treatment and to determine the design soil parameters. This paper describes the design procedure and the acceptance criteria for main works. Typical results from the pilot test and the main works are presented. The phenomenon of a back pressure effect and stagnation of high excess pore pressure occurring with continuing ground settlement is discussed. (TRRL)