This paper presents the performances of prefabricated vertical drains with embankment preloading (conventional PVDs) and with embankment combined with vacuum preloading (Vacuum-PVDs) using the field data obtained from the site of the Suvarnabhumi Airport, Thailand. The flow parameters were illustrated in terms of the horizontal coefficient of consolidation (Ch) and the ratio between the horizontal hydraulic conductivity in undisturbed zone (kh) to the horizontal hydraulic conductivity in smear zone (ks) or (kh/ks). Numerical simulations using axisymmetric FEM by ABQUS software, incorporating horizontal (kh) and vertical (kv) permeabilities, to determine the appropriate (kh/ks) based on back-calculated (Ch) of convential PVD and Vacuum-PVD were done. At considering locations, the Vacuum-PVDs at indicated faster rate of settlement than conventional PVDs by about 1.4 times with slight reduction of the (kh/ks) ratio.