The push-pull test is a powerful site characterization technique that has been applied to a wide range of problems in contaminant hydrogeology. The theoretical and practical apsects of push-pull testing were initially developed to characterize groundwater acquifers but the method has now been extended to saturated and unsaturated soils and sediments as well as to surface water bodies. Dr. Istok and his collaborators have been instrumental in the development of these techniques and he is widely recognized as the world's leading expert push-pull testing. This is the only reference book available on this powerful method.