Yaoqiang Airport is an international airport serving the city of Jinan, China. The soil on the site consists of alternate layers of silty sand, silty clay, silt and clay. An under-consolidated soft clay layer approximately 4 m thick is located at between 7·5 m and 11·5 m depth above a silty clay layer. Soil improvement was proposed to consolidate the site prior to the construction of a runway to eliminate excessive settlement under static and dynamic loads on the runway. The results from field pilot tests for both surcharge preloading and vacuum preloading under the same consolidation pressure of 80 kPa are presented. Soil settlement in the range 20–30 cm was achieved in 80–90 days. For the vacuum treatment, in-situ deep mixing slurry cut-off walls were installed to control vacuum loss in a shallow silty sand layer. Data from the successful full-scale vacuum treatment of the site are also presented