The objective of this research project is to develop a methodology to predict the range of capillary pressure- saturation relationships for contaminated aquifers. This method will be based on the use of independently derived scaling parameters so that if the relationship is known for one system, the relationship for another can be obtained using this procedure. Since the interfacial tension and the contact angle of the system affects the capillary pressure relationships, this dependence needs to be examined. The study will encompass measurements of four types of capillary pressure curves, primary drainage, spontaneous imbibition, forced imbibition and secondary drainage, as well as measurements of interfacial tension and contact angles. The proposal leading to this award was submitted in response to NSF 88-99, Research Initiation Awards. The project is expected to result in improved ability to predict movement of contaminants in aqifers. Currently, there are few capillary pressure measurements available for two-phase systems at hazardous waste sites. This lack of data hampers efforts to use models to describe the relevant processes and to design effective remediation strategies at these sites. This research would help alleviate that problem and reduce the need to make capillary pressure measurements for each contaminant and each soil type that may be present at waste sites.