Nonisothermal multiphase modeling with the T2VOC numerical simulator was used as an integration tool in an in situ remediation project in which trichloroethylene (TCE)-contaminated soil was treated with thermally (steam) enhanced soil vapor extraction. Numerical simulation studies were employed in the iterative conceptualization of the migration of the contaminants and the effects of different treatment operations, in the planning of optimal system design and control of the remediation processes, as well as for integration of information obtained from field investigations during different phases of the project. Modeling proved to be a valuable tool in planning and decision making. It was, however, difficult to forecast the costs or the duration of the project, since the actual TCE mass and distribution was poorly known. The power of modeling lies in its ability to compare the effect of different strategies or measures on the cleanup efficiency, and in studying the associated effects during the treatments.