Danville, IL — 2014-Present
Carbon tetrachloride; as well as lower concentrations of several other VOC constituents in shallow soils and groundwater (0 to approximately 25 feet below ground surface).
To evaluate the potential for utilizing phytoremediation in to treat dissolved-phase contamination and control hydraulic characteristics of a contaminated aquifer.
The TreeMediation implementation consisted of 51 TreeWell units which were installed in 20 by 20 foot spacing at approximately 25 feet below ground surface. One month after the May, 2015 installation, alternations of willow and poplar trees were planted in each unit. In October, 2016, 28 additional TreeWell units were installed to insure total hydraulic capture of the contaminant plume, with aspen and Norway spruce trees planted in April, 2017. includes evaluation of influence on groundwater flow and evaluation of effectiveness of contaminant removal. To accomplish this, groundwater monitor wells were installed upgradient, midgradient, and downgradient relative to the planting configuration and orientation to the source area for each planting area. Selected wells were equipped with data logger transducers to provide constant monitoring of groundwater elevation. Data loggers were added to select monitoring well locations in the 2016 planting areas during spring 2017. The monitoring wells are also sampled on a quarterly basis for analysis of VOCs.
Results to Date:
For the 2015-2019 growing seasons, tree growth and viability were observed to be “very good” for the entire TreeWell study. The tree health assessments do not show any significant indicators of plant stress. The height and canopy of most of the trees in the TreeWell units have continued to increase. Poplar and Willow trees are displaying vigorous growth and, based on hydrogeologic monitoring data, are providing hydraulic capture. The Spruce and Aspen trees planted in 2017 have all survived and are also displaying vigorous growth. Preliminary hydrogeologic data suggest they are on track to perform as designed.