Groundwater contamination by petroleum product releases is a common threat to public health. Contaminant plume dimensions and stability are important to characterize for risk management because they determine the area of influence and the potential duration of exposure. This project will analyze data from about 600 sites to identify central tendencies, variability, and regional trends of hydrocarbon plume characteristics. The data will be obtained from the Iowa Department of Natural Resources electronic database. Statistical analysis will be conducted to answer important questions, such as: What is a typical 'safe' distance down gradient of the source, beyond the reach of the plume? Technical Report Available.