Phytoremediation, a plant-based remediation technology, offers a cost-effective alternative to more traditional remediation and containment methods. Phytoremediation is an aesthetically pleasing approach to site cleanup, with the potential for significant cost savings compared to active remediation systems. Geosyntec practitioners have decades of experience applying phytoremediation, and our broad experience enables us to use these versatile plant-based technologies as part of an integrated approach with other remedial systems, or as stand-alone technology.

As an industry leader in bringing innovative remedial designs to the field, Geosyntec makes use of sophisticated methods in our phytoremediation systems that promote more complete remedial outcomes than conventional phytoremediation methodologies. Our knowledge and experience allow us to capitalize on the inherent advantages of plant-based remediation by successfully implementing these solutions even at locations with challenging site conditions and high contaminant concentrations.

TreeWell Technology Overcomes Limitations of Conventional Phytoremediation

The effectiveness of groundwater remediation using conventional phytoremediation approaches may be limited by compacted soil conditions that impede root penetration, target groundwater that is too deep for root access, or phytotoxicity due to excessively high contaminant concentrations. Geosyntec is a licensed provider of TreeWell technology, an innovative phytoremediation system developed by Dr. Edward Gatliff of Applied Natural Sciences, Inc. TreeWell systems overcome these challenges by utilizing a specialized lined planting unit with optimum planting media that promotes downward root growth, encourages contaminant treatment, and focuses groundwater extraction from a targeted depth interval.  Geosyntec's phytoremediation practitioners have successfully utilized this system at multiple sites in North America to address a wide range of environmental contaminants under diverse hydrogeologic settings.

How TreeWell Technology Works

TreeWell technology overcomes limitations of conventional phytoremediation design and planting methods by targeting groundwater normally inaccessible to plant roots – and therefore out of reach for effective remediation. The TreeWell system is a patented design that focuses groundwater extraction from a targeted depth interval using a specialized planting unit with a Root_Sleeve™ liner.  Targeted groundwater is drawn upward through the planting unit and into the root zone, creating a hydraulic connection between impacted groundwater and the phytoremediation system. Advanced techniques have been developed to address groundwater typically too deep for root contact, at depths greater than 50 feet below ground surface. By targeting only the depth interval requiring remediation, TreeWell technology has been proven to be a cost-effective strategy for hydraulic control and treatment of groundwater contaminant plumes.

An example of a TreeWell phytoremediation system design

Once the TreeWell system is installed, the soil media provides excellent growth conditions for roots and microbes. In addition, the roots of the growing trees release carbohydrates, amino acids and other growth factors that encourage the colonization and proliferation of microflora in the root zone, also called the rhizosphere. The soil column and rhizosphere act as a bioreactor where microbial and plant-based remediation processes (i.e., chemical transformation) occurs, which also serves to reduce possible phytotoxic effects from high contaminant levels. In some cases, the contaminants, such as petroleum hydrocarbons, are degraded in the soil column before coming into direct contact with the roots. In other cases, such as for chlorinated solvents, contaminants can be degraded by reductive dechlorination processes in the saturated zone of the TreeWell soil column, aerobic biodegradation processes in the unsaturated zone, or can be taken up by the plant, where they are either transpired or further metabolized. Typically, a combination of plant and microbial processes occur, resulting in effective contaminant treatment delivered in a passive manner.

Tree species utilized in the TreeWell system generally include those with favorable growth characteristics and high transpiration rates (e.g., hybrid poplars, willows and eucalyptus); however, the TreeWell system can also be used with native and ornamental species to fit the site-specific conditions and goals. When applicable, Geosyntec can coordinate tree selection with landscape architects and site planners to meet their aesthetic needs while also delivering the remedial benefits necessary for effective site cleanup.

Overall, the TreeWell system has proven to be adaptable to a diverse range of settings, contaminant types and contaminant concentrations, with proven, cumulative effectiveness over time. Geosyntec's phytoremediation practitioners have many years of experience using TreeWell technology to effectively remediate our clients' sites, even under challenging conditions. Our knowledge and experience enable us to successfully apply this innovative technology as a cost effective site cleanup strategy. Please contact us to learn more about TreeWell technology and how it can benefit your sites.

Download a Geosyntec TreeWell Technology PDF

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