Obtaining insight on how contaminants change and move in the environment may be important in distinguishing the party responsible for a release, judging if a significant potential for chemical exposure exists, or determining appropriate remedial actions.  EKI is accomplished in fate and transport modeling of contaminants in the vadose zone, groundwater, surface water, and atmosphere.  We have conducted vapor intrusion to indoor air analyses, performed natural attenuation evaluations of chlorinated solvents, petroleum hydrocarbons, hexavalent chromium, pesticides, and other contaminants, and completed groundwater flow simulations ranging from the use of simple analytical equations to numerical computer codes such as MODFLOW.