For the purpose of ground improvement by means of soil flushing systems. Incorporated technique with prefabricated vertical drains have been used for dewatering from fine-grained soils. The laboratory model tests were performed by using the flushing tracer solutions for silty soils and recorded the tracer concentration changes with the elapsed time and flow rates. A mathematical model for prediction of contaminant transport using the PVD technology has been developed. The clean-up times for the predictions on both soil condition indicate more of a sensitivity to the dispersivity parameter than to the extracted flow rate and vertical velocity parameters. Based on the results of the analyses, numerical analysis indicate that the most important factor to the in-situ soil remediation in prefabricated vertical drain system is the effective diameter of contaminated soil.