AbstractAlthough many conventional physical remediation methods are viewed as proven, they often only relocate wastes to other sites or into the air. How do the emerging biological and chemical in situ methods perform in the same applications? This article reviews their results (much of it in the laboratory) as well as their promise of more complete neutralization of hazardous wastes, lower capital costs, and longer‐duration cleanup processes. The optimal method may be a combination of chemical and biological in situ techniques with physical pump‐and‐treat me