The assessment activities undertaken during the Phase II ESA generate data that need to be critically analyzed by the environmental professional (EP) before being interpreted with respect to the contamination of the subject property. During the work planning stage, the EP had to generate certain assumptions about the condition of the subject property. The assumptions are based on the information available at the outset of the assessment. Assumptions also include combining the available information with training, experience, and expertise of the EPs. Based on the assumptions, the EPs create a mental picture of the migration potential of the contaminants on the property. Often, the EPs actually generate a conceptual site model including a drawing with written explanations before collecting the samples. During interpretation, the conceptual site model is evaluated using the data from the assessment activities.