In 1999, Argonne National Laboratory-East (ANL-E) designed and installed a series of engineered plantings consisting of a vegetative cover system and approximately 800 hybrid poplars and willows rooted at various predetermined depths. The plants were installed using various methods including the treatment systems. The goal of the installation was to protect downgradient surface and groundwater by hydraulic control of the contaminated plume. This goal was to be accomplished by intercepting the plume with the tree roots, removing moisture from the upgradient soil area, reducing water infiltration, preventing soil erosion, degrading and/or removing pollutants from the subsoil and groundwater. The EPA Superfund Innovative Technology Evaluation Program (SITE) and ANL-E evaluated the demonstration for a three-year period (1999-2002). The effectiveness of the various plantings was monitored directly through groundwater and soil measurements and samples, and indirectly via plant tissue analysis, microbial surveys, geochemical analysis, soil moisture probes and sap flow monitoring.