Intermediate-Scale Experiments (ISEs)—controlled experiments on porous media that contain physical and/or chemical heterogeneities—are valuable research tools for addressing transport and coupled processes hypotheses. ISEs' unique capabilities stand to benefit research in the scaling of measurements, the study of subsurface microbial populations, and the characterization of coupled processes. But although these experiments have been used for over a decade, applying them presents a number of challenges.

Much work lies ahead in making ISEs more applicable to field problems; increasing their interaction with theoretical, field, numerical, and batch-scale efforts; scaling the knowledge gained from ISEs to interpret field-scale mechanisms; and in developing nonintrusive and nondestructive sampling techniques. The biggest challenge is integrating ISEs into programs that incorporate a number of research techniques as well as several scales of measurement.