Description: This course is intended for environmental professionals seeking an improved understanding of the 3- and 4-phase partitioning models specified under the Washington State Model Toxics Control Act (MTCA). Both models are prescribed in MTCA as predictive tools for deriving soil cleanup levels that are protective of groundwater. Washington State Department of Ecology recently updated two powerful Excel spreadsheets (MTCATPH11 and MTCASGL11) to assist with the complex model calculations. The instructor will lead participants through a number of hands-on exercises that demonstrate the appropriate use and capabilities of the spreadsheet models. The instructor will also discuss model theory, assumptions, limitations, and alternatives such as empirical demonstrations and leaching tests. Participants will have their own computer workstation to apply their knowledge to case study data during numerous hands-on exercises.