TreeWell® System FAQs

What does Applied Natural Sciences do?  

• With our patented TreeWell® technology, we design and implement plant-based remediation systems to address complex soil and groundwater contamination 

• Our systems: 

• provide contaminant mass reduction and hydraulic control  

• allow access to deep groundwater and bedrock aquifers 

• promote in-situ microbial degradation of subsurface contaminants 

• Our technology was developed to overcome limitations of traditional phytoremediation, particularly regarding groundwater remediation. Over the past 30 years, we have expanded the applicability and effectiveness of phytoremediation 

• We have successfully replaced multiple mechanical remediation systems and allowed sites to achieve regulatory closure, which in turn allows our clients to realize substantial lifecycle cost savings 

How does a TreeWell System work? 

• We excavate a large diameter borehole, place our Root_Sleeve™ liner to a pre-determined depth within the borehole, and backfill the excavated hole with soil amended with organic matter. The TreeWell soil column and native bacterial populations help to reduce potential phytotoxic effects and allow the targeting of specific water-bearing strata 

• Trees act as pumps, moving groundwater upward through the amended soil column 

• Trees also sustain a bioreactor effect and stimulate microbial degradation 

• Residual contaminants can also be degraded within the plant, sequestered within plant tissues, or transpired into the atmosphere  

• Trees’ water consumption can affect the flow direction of groundwater and shift the direction of a migrating contaminant plume 

What depths can TreeWell Systems target? 

• Our TreeWell systems allow access to deep groundwater and bedrock aquifers 

• The soil texture we design within the TreeWell system ensures sufficient capillary rise so that selected fast-growing trees can access the targeted groundwater within a single growing season  

• Trees within the TreeWell units generally target groundwater of up to 20 ft bgs without need for continuous irrigation; strategic temporary supplemental irrigation can allow standard TreeWell units to access groundwater up to approximately 35-40 feet bgs 

• A Straw TreeWell System, which is a closed-bottom version of a standard TreeWell unit, can be employed to address contaminated groundwater exceeding depths of 100 feet bgs—head pressure in the target stratum needs to be sufficient to move groundwater upward to the upper screen inside the Straw TreeWell unit 

What trees are used in TreeWell units? 

• Most commonly, willows and poplars are planted because they root aggressively and can move large volumes of water  

• Species diversity can be helpful in managing the unknowns (various stressors that can affect tree health) of a site, so we have a short list of other high biomass-producing trees with good water consumption rates we may select tailored to each site 

How do the trees survive in circumstances generally considered phytotoxic? 

• Many contaminants we target are metabolized by microbes within the soil column before encountering the tree’s roots 

• The TreeWell soil column, which has been filled with organic matter amended sandy loam soil, greatly reduces phytotoxic effects of target contaminants to the TreeWell System tree 

What contaminants have been successfully treated by TreeWell Systems? 

• VOCs, SVOCs, pesticides, petroleum hydrocarbons, agricultural inorganics (i.e. nitrates, ammonium, phosphorous), tritium, and more recently solubilized metals in groundwater impacted by coal combustion residuals (CCRs) such as lead, arsenic, zinc, boron, and cadmium 

• Several TreeWell System pilot-scale studies are underway to evaluate fate, transport, and remediation potential of PFAS compounds 

Where do the contaminants go/what is the fate of the contaminants within the TreeWell System? 

• In-situ microbial degradation within the TreeWell System’s soil column is common with many targeted organic contaminants; therefore, the tree will not need to be disposed of in the future 

• Less frequently, contaminants are taken up and degraded/metabolized within the tree, sequestered within tree tissues, or transpired into the atmosphere