AbstractDemonstrations of remedial technologies are undertaken to show that the treatment process causes some level of contaminant reduction, and to follow important operating or process parameters during treatment. In projects utilizing biological processes, it is important to demonstrate that enhanced metabolic activity — the proposed treatment mechanism — actually is responsible for the contaminant reduction. Results from two field‐scale bioremediation projects are used to highlight the importance of remedial objectives or endpoints when designing proper controls and selecting appropriate analytical methods. The results are also used to illustrate some of the limitations of using the “total”; concentration of a mixture for evaluating the effectiveness of a technology.