Västerås is a city with an industrial heritage. One of the larger companies in Västerås is ABB AB, which has multiply businesses located at the area Finnslätten. High concentrations of trichloroethene (TCE) were found in the soil and groundwater at Finnslätten 1 during a phase II environmental site assessment. Due to the result of the assessment a supplementary investigation and a site specific risk assessment were made of building 358. The source zone and plume of trichloroethene have not been characterized even after several investigations at the site. The aim of this study was to make a risk assessment of three other buildings inside the area were degreasing with TCE have historical taken place. The collected information resulted in a risk class 2 of the three objects and shows that the buildings might be potential pre-emission sources of trichloroethene. The second aim contains a comparison between traditional and alternative approaches to enlighten the importance of effective characterization methods. Two potential characterization strategies were chosen; TRIAD approach and CMF approach. The result showed the importance of systematic project planning, dynamic work planning strategy and the use of multiple techniques to form the best “hybrid” during characterization of DNAPL. In order to bring the investigation to a successful conclusion it is of great importance to consider the uncertainties or diminish the uncertainties by collecting essential information.