U.S. EPA Contaminated Site Cleanup Information (CLU-IN)


U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Phytotechnologies

Application

Like all other remediation technologies, phytotechnologies are site specific and appropriate only under certain conditions. The major limitations are depth, area, and time.

Phytoextraction and phytovolatilization are technologies that remove contaminants from environmental media. Contaminant destruction can be accomplished using rhizodegradation and phytodegradation. These remediation mechanisms can be combined with containment. Phytoremediation applications for removal or destruction include groundcovers, tree stands for remediating deeper soil and groundwater, constructed treatment wetlands, and riparian buffers.

Where reducing contaminant mobility is the primary objective, the main focus should be on rain interception and/or groundwater uptake and the evapotranspiration from both processes. Contaminant solubility and availability must be considered as well. Hydraulic barriers and vegetated caps and covers can be used simply to control and contain contaminants. Phytotechnology applications that combine containment with remediation can include covers that stabilize soil and phytoremediate contaminants, tree stands that create both a hydraulic barrier while remediating impacted soil and groundwater, constructed wetland treatment systems, and riparian buffers (ITRC 2009). Detailed information on vegetated covers is available on the CLU-IN pages for Evapotranspiration Covers.

The Case Study Databases section below identifies searchable databases that contain case studies for a wide range of phytotechnology applications. The rest of the case study resources are grouped by contaminant type.

NOTE: For links to additional information that are identified only by author and date (e.g., Rieske and Lewis 2008), full citations are provided in the Additional Information Bibliography.


Adobe PDF LogoITRC (Interstate Technology & Regulatory Council). 2009. Phytotechnology
Technical and Regulatory Guidance and Decision Trees, Revised
. Phyto-3


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Case Study Databases | Chlorinated Organic Compounds | Inorganics, Metals, and Radionuclides | Multiple Contaminants | Munitions Constituents | Petroleum Products | Additional Information Bibliography

Case Study Databases

Phytotechnology Project Profiles Database

Over 165 projects encompassing international, completed, and ongoing phytotechnology applications have been found in the literature and documented in this database. Each profile contains information about relevant site background, the types of contaminants treated, type of vegetation used, phytotechnology mechanisms, planting date, project size, location, cost, monitoring and performance results, as well as points of contact and references.

Remediation Technology Demonstration Project Profiles

Over 20 phytotechnology demonstration projects are documented in this database.

Chlorinated Organic Compounds

Aberdeen Proving Ground (Edgewood Area)
U.S. EPA Superfund Information System.

In 1996, Aberdeen Proving Ground and EPA began a pilot-scale phytoremediation study the J-Field area to evaluate the capability of hybrid poplar trees to reduce a groundwater plume of VOCs, primarily chlorinated solvents. Eventually implemented as part of the legal remedial alternative for the site, the phytoremediation system has proven to be an effective, low-cost solution to groundwater contamination. See the link to 'Additional Site Documents' for the ROD, amendment, and 2008 5-year review. Additional information: (Schneider et al. 2002Adobe PDF Logo); (Hirsch et al. 2003); (Jackson et al. 2005); (2008 5-year reviewAdobe PDF Logo)

Adaptive Treatment Strategy Addresses Extensive DNAPL Contamination
Technology News & Trends, Issue 35, April 2008

The Cascade Corporation is remediating a 47-acre operative manufacturing facility near Troutdale, OR, using a series of innovative technologies to address TCE in the unsaturated zone and groundwater. Initial cleanup efforts focused on pump and treat with air stripping and subsequent installation of a french drain with air stripping to treat the upper gravel aquifer. Additional remedies include dual-phase extraction, SVE, air sparging, phytoremediation, biostimulation, and a biobarrier. In 2001, 800 poplar trees were planted to serve as a polishing step for the shallow contaminated water downgradient of the french drain. The configuration of planted trees is sufficiently long that the water entering the root zone during the dormant season does not exit before the trees become active again in spring. Additional information: Oregon DEQ Web page: Cascade Corporation

Adobe PDF LogoAssessment and Comparison of Two Phytoremediation Systems Treating Slow-Moving Groundwater Plumes of TCE
A.C. Lewis, Master's thesis, Ohio University, 158 pp, 2006

The effects of differences in planting technique and tree species used on groundwater uptake and TCE removal were analyzed for the X-740 and X-749 phytoremediation system installed in 1999 and 2003, respectively, DOE's Portsmouth Gaseous Diffusion Plant. Although the plantings initially were expected to reach maturity in 2 years, 4 years passed before the system began noticeably influencing the groundwater. UPDATE: After 10 years of monitoring, the X-740 system's performance was judged insufficient to meet remedial objectives owing to the depth to groundwater, a fundamental physical limitation to phytoremediation effectiveness. Additional information: (Lewis and Baird 2005); (Rieske and Lewis 2008); (Looney et al. 2010Adobe PDF Logo);

Adobe PDF LogoD-Area Drip Irrigation-Phytoremediation Project: SRTC Final Report
E.W. Wilde, et al.
WSRC-TR-2002-00080, 100 pp, 2003

The system involved pumping water from the TCE-contaminated aquifer and discharging the water into overlying plots below the surface using drip irrigation. The plots contained pines and cottonwoods.

Adobe PDF LogoDemonstration of Phytostabilization of Shallow Contaminated Groundwater Using Tree Plantings Travis Air Force Base, California: Final Addendum Report No. 3 to the Interim Technical Report
Air Force Center for Environmental Excellence, 150 pp, 2005

The purpose of this demonstration project was to test the ability of selected plants to remove groundwater through uptake and consumption to contain or control the migration of dissolved contaminants (i.e., PCE, TCE, and daughter products).

Demonstration-Site Development and Phytoremediation Processes Associated with Trichloroethene (TCE) in Ground Water, Naval Air Station-Joint Reserve Base Carswell Field, Fort Worth, Texas
S.D. Shay and C.L. Braun.
U.S. Geological Survey Fact Sheet 2004-3087, 4 pp, 2004

The objective of this demonstration project is to determine the effectiveness of eastern cottonwoods in decreasing the mass of dissolved TCE in ground water through chemical, physical, and biological means Plant 4. Additional information on this project is available in the Superfund Innovative Technology Evaluation ReportAdobe PDF Logo (2003) and the ESTCP Cost and Performance ReportAdobe PDF Logo (2006).

Deployment of Phytotechnology in the 317/319 Area Argonne National Laboratory-East: Innovative Technology Evaluation Report
EPA 540-R-05-011, 88 pp, 2003

In 1999, Argonne National Laboratory-East installed a vegetative cover system and approximately 800 hybrid poplars and willows to contain soil erosion and address chlorinated organics (e.g., PCE and TCE) and tritium in the ground water. The treatment period will continue for up to 20 years. This report presents results from the first few years of site sampling, monitoring, and modeling. 2005 Growing SeasonAdobe PDF Logo; 2009 Growing SeasonAdobe PDF Logo

Adobe PDF LogoEvapotranspiration Buffer Leachate Management System Installation Work Plan, Operable Unit 2: Landfill 4, Former Chanute Air Force Base, Rantoul, Illinois: Addendum 1 for Landfill 2
Air Force Civil Engineer Center, Environmental Center of Excellence, 43 pp, 2013

An ET buffer leachate management system of hybrid poplars and willows is being implemented for leachate migration control at Landfill 2, where TCE, DCE, and vinyl chloride in groundwater or leachate have been detected above the landfill groundwater monitoring concentration limits. This work plan provides the design basis, criteria, and details for (1) hydraulics and (2) tree selection and plantin

Adobe PDF LogoFY02 Final Report on Phytoremediation of Chlorinated Ethenes in Southern Sector Seepline Sediments of the Savannah River Site
R.L. Brigmon, F.M. Saunders, D. Altman, E. Wilde, C.J. Berry, M. Franck, P. McKinsey, S. Burdick, F. Loeffler, and S. Harris. WSRC-TR-2002-00557, 171 pp, 2003

This final report details the operations and results of a 3-year TCE Seepline Phytoremediation Project adjacent to Tims Branch in the Savannah River site A/M Area. Phytoreactor 1 was planted with loblolly pines, Phytoreactor 2 with hybrid poplars, Phytoreactor 3 was the non-vegetated control to evaluate natural attenuation progress, Phytoreactor 4 was planted with sterile Vetiver grass, and Phytoreactor 5 was set up as a wetland system. Additional information: (Stanhope et al. 2008)

Fate Processes in a Pilot-Scale Natural Treatment System for Chlorinated VOCS
J. Pardue, M. Worthy, F. Symmes, and M. Last.
Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2008). Battelle Press, Columbus, OH. ISBN 1-57477-163-9, Abstract B-076, 2008

A four-year pilot study of a biofilter phytobed (BFP) was conducted to develop a natural treatment system for VOCs in the groundwater an NPL site in New England. This paper describes the fate processes identified for chlorinated ethenes and chlorinated ethanes in the BFP system over the length of the study. Removal of chloroethenes (1,2-DCE, VC, and trace amounts of TCE) in the pilot system has approached 100% since December 2003 without addition of exogenous carbon sources. Removal of TCA has been similarly effective, with nearly 100% removal. Taken together, results demonstrate that the system performs by encouraging rapid dechlorination of parent VOCs, sustained by the highly organic bed materials, which also serve to retard VOC transport through the bed. Longer abstract.

Federal Remediation Technologies Roundtable Cost and Performance Case Studies

Measuring the Removal of Trichloroethylene from Phytoremediation Sites Travis and Fairchild Air Force Bases
Klein, Heather A., Master's thesis, Utah State University, Logan. 113 pp, 2011

This thesis discusses the quantification of total TCE removal from phytoremediation demonstration plots the Travis and Fairchild sites using tree coring and volatilization of TCE from leaves, tree trunks, and soil. The removal of TCE was estimated to be 18 g/yr at Fairchild and 839 g/yr at Travis, mainly from leaf and soil volatilization. Based on these estimates, phytoremediation removed 5% and 50% of the mass of TCE in the groundwater at the Fairchild and Travis Air Force sites, respectively.

Phytoremediation Reduces Mechanical Pumping and Ex-Situ Treatment of Ground Water
Technology News & Trends, Issue 24, May 2006

A ground-water phytoremediation system comprising a 0.8-acre stand of willows was installed in 1999 the Solvents Recovery Service of New England Superfund site in Southington, CT, for seasonal pump and treat of contaminated ground water, thereby reducing the extent of mechanical pumping and treatment.

Adobe PDF LogoPhytoremediation of TCE in Groundwater Using Populus
J. Chappell. Status Report prepared for the U.S. EPA Technology Innovation Office under a National Network of Environmental Management Studies Fellowship, 59 pp, 1998

Adobe PDF LogoPhytoremediation of Volatile Organic Compounds in Groundwater: Case Studies in Plume Control
A. Van Den Bos. Status Report prepared for U.S. EPA's Technology Innovation Office under a National Network of Environmental Management Studies Fellowship, 44 pp, 2002

Adobe PDF LogoPush-Pull Tests to Quantify in Situ Degradation Rates a Phytoremediation Site
M.T. Pitterle, R.G. Andersen, J.T. Novak, and M.A. Widdowson.
Environmental Science & Technology 39(23):9317-9323(2005)

A creosote-contaminated site in Oneida, TN, has been the subject of extensive monitoring and research since the installation of 1,146 hybrid poplar trees in 1997. To determine in situ aerobic respiration rates the site and to assess the contribution of hybrid poplar trees to the remediation of PAHs in groundwater, push-pull tests were conducted by injecting reactive tracers (a solution containing dissolved oxygen and naphthalene) with a nonreactive tracer (bromide) into the aquifer. Additional information: (Waters 2003); (Pitterle 2004); (Booth 2005); (Andersen 2006); (Marr et al. 2006); (Widdowson et al. 2007Adobe PDF Logo); (Andersen et al. 2008)

Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, June 2006
R.S. Dinicola and R.L. Huffman.
U.S. Geological Survey Open-File Report 2007-1430, 38 pp, 2007

The Navy selected phytoremediation combined with on-going natural attenuation processes as the preferred remedy for contaminants beneath OU-1, a 9-acre inactive landfill. Two hybrid poplar plantations were planted on the landfill in the spring of 1999 to remove and control the migration of chlorinated VOCs in the shallow groundwater. Additional information: (Dinicola and Huffman 2009); (Dinicola and Huffman 2012)

Summary of Operations and Performance of the Murdock Site Restoration Project in 2007
L.M. LaFreniere.
ANL/EVS/AGEM/TR-08-07, 418 pp, 2008

Innovative technologies are being used to remove carbon tetrachloride contamination from a shallow aquifer underlying Murdock, NE, as well as from water naturally discharged to the surface the headwaters of a small creek. The principal elements of the remediation/reclamation approach are a ground-water extraction well and spray irrigation treatment system, a phytoremediation (2,000 trees representing 6 species) and buffer vegetation (deep-rooted native grasses) planting area, and constructed wetlands. The remediation systems functioned successfully as designed during the second full year (2007) of system operation.

Inorganics, Metals, and Radionuclides

Adobe PDF Logo100-N Area Strontium-90 Treatability Demonstration Project: Phytoextraction Along the 100-N Columbia River Riparian Zone Field Treatability Study
Fellows, R.J., J.S. Fruchter, C.J. Driver, and C.C. Ainsworth.
PNNL-19120, 52 pp, 2010

A field treatability demonstration plot was established on the Columbia River shoreline alongside the 100-K West water intake the end of January 2007. Within a chain-link fence 3.05 m high, ~10 x 25 m in size, and screened with fine-mesh metal to keep out small animals, 60 coyote willows were placed in six slightly staggered rows with 1-m spacing between plants. Over the following 2 years, the plants continued to flourish even when river waters submerged the site for part or all of the day. Projected biomass yields suggest the trees could prove effective in removing Sr-90 from the 100-NR-2 riparian zone.

Adobe PDF LogoAlcoa-Mt. Holly Zero Process Water Discharge Using Phytotechnology
L. Schmelter.
Proceedings of the 2008 South Carolina Water Resources Conference, 14-15 October 2008, Charleston, South Carolina. 4 pp, 2008

The Alcoa-Mt. Holly aluminum reduction facility generates ~70,000 gallons of wastewater each day. In 2002, a pilot project consisting of 1.33 acres of OP-367 hybrid poplars (1,200 trees) and 1.33 acres of native grasses was permitted under a no-discharge permit. By their sixth growing season, the trees reached a height of 35 ft and a girth of 1 ft. The mortality rate has been 9.8%, due largely to isolated wet conditions in low-lying areas, and willows have been planted as replacements. As the trees matured, application of total effluent to the spray field increased from 9.6% in 2005 to 19.8% in 2007. The tree plot has outperformed the grass plot based on field observations and flow data. Soil and groundwater monitoring data have shown no increase in constituents of interest (fluoride, copper, nickel, and zinc) from the effluent spray. A full-scale phytotechnology expansion to 13.1 acres is being designed.

Adobe PDF LogoApplication of Agronomic Practice Improves Phytoextraction on a Multipolluted Site
D. Claus, H. Dietze, A. Gerth, W. Grosser, and A. Hebner.
Journal of Environmental Engineering and Landscape Management 15(4):208-212(2007)

In the largest phytotechnology project of its kind in Europe—a surface area of 27,000 square meters planted primarily with common reed—phytoremediation of metals-contaminated soil and sediment has been underway since 1995 a former sewage sludge dewatering plant in Schladitz near Leipzig. An extensive monitoring and analysis program scheduled to conclude in 2012 is ongoing to evaluate remediation progress. Results to date indicate that the type of plant species is the most important factor affecting the extent of metal removal.

Arsenic Uptake by Poplars and Implications for Use in Hydraulic Control of Groundwater
A. Lewis-Russ, R. Henning, D. Fenske, E. Hicks, J. Haramut, M. Goan, J. Perkins, and C. Bury.
Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2008). Battelle Press, Columbus, OH. ISBN 1-57477-163-9, Abstract B-080, 2008

The efficacy of hybrid poplars for groundwater withdrawal was evaluated in a pilot test a site adjacent to a river in the upper Midwest. The groundwater table is shallow (4 to 6 ft bgs) and contains elevated arsenic concentrations. Groundwater must be withdrawn to avoid potential mounding within a proposed containment wall. For the pilot test, nearly one acre of poplars (over 1,000 trees) was planted in June 2006. Monitoring shows that the trees are affecting groundwater levels, and the treed area has been expanded. Monitoring results also indicate that movement of arsenic from groundwater to the surface should not prevent use of the trees for hydraulic control at this site. Longer abstract.

Adobe PDF LogoConstructed Wetlands for the Remediation of Blast Furnace Slag Leachates
M.K. Banks, A.P. Schwab, J.E. Alleman, J.G. Hunter, and J.C. Hickey.
FHWA/IN/JTRP-2006/3, 202 pp, 2006

A field-scale subsurface constructed wetland was emplaced to mitigate the impacts of leachate from slag used in a roadbed. The leachate had a greenish/yellow color and hydrogen sulfide odor a pH of 12. The wetland was effective in reducing pH, total dissolved solids, salinity, and sulfate and was most effective under low-flow conditions and extended retention times between surges of leachate into the wetland.

Federal Remediation Technologies Roundtable Cost and Performance Case Studies

Long-Term Performance of a Constructed Wetland for Metal Removal
Knox, A.S., E.A. Nelson, N.V. Halverson, and J.B. Gladden.
Soil and Sediment Contamination 19(6):667-685(2010)

This paper summarizes four years of data collected from the A-01 treatment system, a surface-flow wetland planted with giant bulrush to remove metals from the A-01 NPDES outfall effluent the Savannah River site. Rather than sequestering the metals, the bulrush plants provide a continuing source of organic material to the sediments where bacteria and fungi decompose the plants and maintain anoxic conditions, which works to capture and immobilize the metals in the sediments. Yearly growth, dieback, and decomposition of the plants keep the soil ecosystem functioning year after year. Two wetland cells began receiving continuous water flow for treatment when construction of the system was completed in early fall 2000. Cu, Hg, Z, and Pb concentrations in the outfall water decrease by 60 to 80% during passage through the system. Longer abstract. Additional information: (Lehman et al. 2001Adobe PDF Logo); (Nelson et al. 2002); (Lehman et al. 2002Adobe PDF Logo); (Knox et al. 2004Adobe PDF Logo); (Knox et al. 2005aAdobe PDF Logo); (Knox et al. 2005b); (Nelson and Gladden 2007Adobe PDF Logo)

Monitored Natural and Enhanced Attenuation of the Alluvial Aquifer and Subpile Soils at the Monument Valley, Arizona, Processing Site: Final Pilot Study Report
U.S. DOE, Office of Legacy Management. LMS/MON/S07670, 106 pp + 124 pp appendix, 2013

In pilot studies designed to evaluate at field scale proposed remedies for ammonium, nitrate, and sulfate in an alluvial aquifer at the Monument Valley Processing Site, land-farm phytoremediation involved irrigating a crop of native shrubs with nitrate-contaminated groundwater pumped and piped from the alluvial aquifer.

Adobe PDF LogoAn Overview of the Phytoremediation of Lead and Mercury
J.R. Henry. Status Report prepared for the U.S. EPA Technology Innovation Office under a National Network of Environmental Management Studies Fellowship, 55 pp, 2000

Phytoremediation with Innovative Irrigation Technique Treats Arsenic-Contaminated Soil
Technology News & Trends, Issue 39, Dec 2008

In the summer of 2005, approximately 20,000 Chinese brake ferns of a patented variety were installed the Crozet Orchard near Crozet, VA, to address residential properties exhibiting high concentrations of arsenic in soil.

Adobe PDF LogoProof-of-Concept of the Phytoimmobilization Technology for TNX Outfall Delta: Final Report
D.I. Kaplan, S.M. Serkiz, A.S. Knox, T.G. Hinton, R.R. Sharitz, and B.P. Allen.
WSRC-TR-2001-00032, 99 pp, 2001

This project involved phytoextraction of actinium, cobalt, chromium, mercury, lead, radium, thorium, and uranium from soil by indigenous trees, ferns, and grasses, followed in the winter months by immobilization of the contaminants leaching from the fallen leaves and decaying plant matter in a geotextile embedded with mineral-sequestering agents.

Adobe PDF LogoResults of the 1998 Field Demonstration and Preliminary Implementation Guidance for Phytoremediation of Lead-Contaminated Soil the Twin Cities Army Ammunition Plant, Arden Hills, Minnesota
A.D. Behel, Jr., P.A. Pier, R.A. Almond, J.J. Kelsoe, and J.J. Hoagland.
DTIC: ADA373496, 380 pp, 1999

This report describes the first-year (1998) results of a 2-year field demonstration conducted to determine the feasibility of metals phytoextraction from soil. The report also provides preliminary guidance for implementing phytoextraction of ionic Pb. Soil acidifiers and a chelating agent were used to increase the water solubility of Pb and its availability to plants. Corn plants performed near expectations, but white mustard did not.

Spring Valley, Washington, DC: A Formerly Used Defense Site
U.S. Army Corps of Engineers, Baltimore District Web site.

In 2004, the Corps of Engineers initiated a field verification study to evaluate the potential of phytoremediation to address elevated arsenic soil concentrations Spring Valley. The study began with 14 study sites in two residential areas and one public access area using 3 species of hyperaccumulating ferns. This ongoing project was expanded in 2005 and again in 2008. Phytoremediation Study Fact Sheet (2005)Adobe PDF Logo; 2005 Arsenic Phytoremediation Field Verification Study; (Hughes and Blaylock 2006)

Adobe PDF LogoTritium Phytoremediation Project: BGC Southwest Plume Cleanup
Savannah River Site Fact Sheet, 3 pp, 2003

Pines, hardwoods, and other plants have been installed the Savannah River site burial ground complex (BGC) to take up tritium-contaminated water via root systems and transpire trace amounts of tritium to the atmosphere through foliage. The irrigation system for the phytoremediation technology began operation in 2001. Although this system was designed to reduce tritium discharges to Fourmile Branch by 25%, tritium concentrations in the discharges to Fourmile Branch have decreased by over 50%. Additional information: (Riha and Rebel 2004Adobe PDF Logo); (Hitchcock et al. 2005Adobe PDF Logo); (Rebel et al. 2005); (Prater et al. 2013Adobe PDF Logo)

Multiple Contaminants

Aberdeen Pesticide Dumps
U.S. EPA Superfund Information System.

ESDs modifying the cleanup approach from the 1993 ROD for contaminated groundwater the Farm Chemicals, Twin Sites, and Fairway Six Areas were issued in 1994 and 1997 to list additional COCs (benzene hexachloride isomers, toxaphene, DDT, DDE, dibromochloropropane, xylene, ethyl benzene, toluene) and include phytoremediation as part of the cleanup strategy. Phytoremediation and MNA also were selected for the McIver Area in a 1999 ROD. According the 2008 5-year review, the remedy is functioning as designed. Groundwater concentrations of the COCs are declining, and the poplar trees are robust and thriving. 2008 5-year reviewAdobe PDF Logo

Adobe PDF LogoThe Bioremediation and Phytoremediation of Pesticide-Contaminated Sites
C. Frazar. Summary prepared for U.S. EPA's Technology Innovation Office under a National Network of Environmental Management Studies Fellowship, 55 pp, 2000

Adobe PDF LogoCase Studies of Phytoremediation of Petrochemicals and Chlorinated Solvents in Soil and Groundwater
V.A. Nzengung.
Proceedings of the 2005 Georgia Water Resources Conference held April 25-27, 2005, the University of Georgia, Athens, Georgia.

Three case studies discuss phytoremediation of VOCs. I. Willow tress planted over a petroleum spill removed 90% of residual contaminants from the soil and groundwater after 3 growing seasons. II. Poplars and willows were used as a polishing step for a chlorinated solvent plume following chemical oxidation of the source. III. The contribution of plants in the attenuation of a mixed plume of hydrocarbon and chlorinated solvent constituents Kennedy Space Center was confirmed by analysis of geochemical and hydrogeological data.

Adobe PDF LogoConstructed Wetlands: Passive Systems for Wastewater Treatment
R. Lorion. Technology Status Report prepared for U.S. EPA's Technology Innovation Office under a National Network of Environmental Management Studies Fellowship, 29 pp, 2001

Dredged Material Reclamation the Jones Island Confined Disposal Facility. Innovative Technology Evaluation Report
EPA 540-R-04-508, 117 pp, 2003

Concurrent treatability studies conducted in 2001 and 2002 by the U.S. Army Corps of Engineers using hybrid corn, indigenous willow, and local grasses indicated that plants would survive in the dredged material and reduce levels of PAHs, PCBs, and DRO.

Federal Remediation Technologies Roundtable Cost and Performance Database

Field Note: Irrigation of Tree Stands with Groundwater Containing 1,4-Dioxane
A.M. Ferro and C.E. Tammi.
International Journal of Phytoremediation 11(5):425-440(2009)

Coniferous and deciduous tree stands recently were planted on a closed landfill over a 14 ha area as part of a natural treatment system for recovered groundwater containing 1,4-dioxane (< 10 mg/L), among other components. This paper describes the pilot study and the feasibility studies performed prior to full-scale planting. Longer abstract. Additional information: (Ferro et al. 2005Adobe PDF Logo); (Ferro and Tammi 2007Adobe PDF Logo); (Ecolotree 2007Adobe PDF Logo); (Dahlgren 2009Adobe PDF Logo); (Ferro et al. 2013 [Abstract])

In-Situ Bioremediation and Phytoremediation of Contaminated Soils and Water: Three Case Studies
W.L. O'Niell and V.A. Nzengung.
Environmental Research, Engineering and Management 4(30):49-54(2004)

This paper presents 2 phytoremediation case studies. I. In 1997, a gasoline release occurred from a gasoline line located near the city of Athens, GA. Gasoline flowed into a ravine and then into a wetland on the banks of a creek. An initial phytoremediation effort failed. After further study, the ravine soils were planted with wetland plants and 290 white willows in April 2001. After 2 successful growing seasons, groundwater samples showed very low levels of BTEX constituents, and 85% of the BTEX mass had been removed from the soils. After 3 growing seasons, more than 90% of the BTEX mass was gone. II. At a U.S. Navy dry cleaning facility in Orlando, FL, PCE and daughter products contaminated both soil and groundwater and were transported 300 m into an adjacent lake. The soil was amended with compost and planted in March 2002 with 3,200 poplar tree cuttings. Two years after installation, the tree canopy was 75% closure over the planted areas, PCE levels were decreasing, PCE metabolite concentrations were increasing, and the CVOC plume was no longer reaching the lake.

Adobe PDF LogoInnovative Phytoremediation Process Utilizes Landfill Leachate as a Resource in Lieu of Traditional Disposal as a Waste
Environmental Engineer: News, Current Events & Careers 38(2):32(2012)

At Gulf Coast Area Landfills, Biloxi, MS, leachate problems compounded rapidly when leachate production suddenly increased from 350,000 to 3,500,000 gal/yr. For disposal, the leachate was transported in tanker trucks to a municipal WWTP 150 miles away. A 3-acre demonstration of phytoremediation for on-site leachate management focused on using vetiver, a perennial grass native to India. Designated a non-invasive plant by USDA, vetiver is well suited for leachate utilization due to its tremendous water and nutrient demand, fast growth, and high tolerance of extreme environmental conditions. The contractor designed and installed an automated leachate pre-treatment and distribution system that responds to changes in weather conditions and leachate production and quality. The leachate flows through 35,000 feet of underground piping and a specially-designed subsurface drip irrigation system designed for desktop monitoring and management. The system has been operating successfully. Additional information: 29 slidesAdobe PDF Logo

Adobe PDF LogoLandfill Leachate Management by Application to Short Rotation Willow Coppice
G.R. Alker, A.R. Godley, and J.E. Hallett.
Proceedings Sardinia 2003, Ninth International Waste Management and Landfill Symposium, S. Margherita di Pula, Cagliari, Italy. CISA, Environmental Sanitary Engineering Centre, Italy. 12 pp, 2003

Two operational-scale field trials were managed over 5 years to investigate the feasibility and sustainability of landfill leachate management by its application to plantations of short-rotation willow coppice. Plant yields were improved by leachate application. Almost complete removal of ammoniacal nitrogen by nitrification and plant uptake and a reduction in mass of N by 80% was observed. Most of the other leachate components were held within the soil without detriment during the growing season and were released during the winter periods lower concentrations than they were applied, following dilution by rainfall.

Long-Term Monitoring (1993-2007) of the Effect of Hybrid Poplar Trees on a Petroleum-Hydrocarbon Contaminated Ground-Water System
J.E. Landmeyer, A.R. Contrael, and T.N. Effinger.
International Conference on Phytotechnologies, Denver, Colorado, September 2007

Changes in ground-water levels and contaminant geochemistry were observed in a shallow aquifer contaminated with coal-tar near Charleston, SC, before and after the installation of a grove of 600 hybrid poplar trees. Longer Abstract

Adobe PDF LogoLong-Term Performance of an Integrated CTW/Phyto Cap System
Kwan, W. and W. Eifert.
Regional Workshop: Introduction to Phytotechnologies and Water Balance (Evapotranspiration) Covers, December 14 & 15, 2011, San Francisco, California. 41 slides, 2011

Near Williamsburg, VA, an inactive, unlined, 34-acre industrial waste landfill surrounds a 16-acre jurisdictional wetland. Leachate containing high levels of zinc, iron, and acidity discharges into the wetlands and affects the sediment. To manage this contamination, a staged, constructed treatment wetland (CTW) was incorporated into the existing jurisdictional wetland in 1999; and a tree plantation (phyto cap) was installed over key landfill areas in 2001.

Adobe PDF LogoManufactured Soil Field Demonstration for Constructing Wetlands to Treat Acid Mine Drainage on Abandoned Minelands
C.R. Lee, D.L. Brandon, and R.A. Price. ERDC-TN-DOER-D9, 15 pp, 2007

An abandoned 35-acre acid mine drainage (AMD) site Vintondale, PA, was reclaimed as a recreational park and passive remediation facility. The demonstration crew planted 5,000 trees and shrubs in extremely acidic overburden soil and used a blend of dredged material, waste-paper fiber, and processed cow manure to produce a substrate to support plant life in the constructed wetland as a final polishing treatment for AMD.
Additional information: The AMD&ART Project

Adobe PDF LogoMonitoring the Effectiveness of Phytoremediation and Hydrologic Response an Agricultural Chemical Facility
W.M. DeVita and M. Dawson.
Center for Watershed Science and Education, Univ. of Wisconsin, Stevens Point. Project WR04R007, 15 pp, 2004

An active aerial agricultural chemical facility located near Bancroft, WI, has a history of soil and groundwater degradation. Dinoseb (2-sec-butyl-4,6-dinitrophenol) is the primary contaminant of concern. Sandy soil, shallow groundwater, and other factors make this a prime site to study the effects of phytoremediation. In June 2000, a mixture of 834 hybrid poplars, willows, and cottonwoods was planted in an effort to degrade and/or retard the movement of pesticides. Additional information: (DeVita and Dawson 2006Adobe PDF Logo)

Adobe PDF LogoMonitoring Remediation with Trembling Leaves: Assessing the Effectiveness of a Full-Scale Phytoremediation System
E.I. McLinn, J.E. Vondracek, and E.A. Aitchison.
Phytoremediation, Wetlands and Sediments: The Sixth International in Situ and On-Site Bioremediation Symposium (San Diego, 2001). Battelle Press, ISBN: 9781574771152, 121-128, 2001

At the Ashland, Inc. facility in Milwaukee, WI, a RCRA Corrective Action site, historic accidental spills contaminated the soil and groundwater with petroleum-related organics, PAHs, and chlorinated organics, such as PCE and TCE. In May 2000, Ashland and site contractors installed 485 10-15 ft tall hybrid poplar trees. This paper discusses the importance of tailoring environmental monitoring phytoremediation sites to site conditions and the remedial objectives.

Naval Surface Warfare Center, Dahlgren, VA: Site 17 - 1400 Area Landfill, Soil Cap with Phytoremediation
R. Mayer.
RPM News 4-6(Summer 2001)

A vegetative cap was implemented the Site 17/1400 Area Landfill to minimize migration of contaminated ground water through hydraulic control by groves of phreatophytic trees, limit rain water reaching the water table, and stabilize the soil cover. This article details the construction of the remedy in 2000, lists the tree species selected, and describes the lessons learned during the course of installing a plant-based system. The Site 17 Landfill originally covered about 6 acres. As a result of this project, the landfill now covers 3.5 acres and is properly controlled. The cost of the project was $1,800,000. Additional information: 2010 UpdateAdobe PDF Logo

Adobe PDF LogoPhytoremediation Field Studies Database for Chlorinated Solvents, Pesticides, Explosives, and Metals
A. Hoffnagle and C. Green. Compiled during an internship with U.S. EPA's Office of Superfund Remediation and Technology Innovation, 168 pp, 2004

Adobe PDF LogoPhytoremediation of Contaminated Sites Using Wood Biomass
D. Rockwood, G.R. Alker, R.W. Cardellino, L.Q. Ma, and C. Tu.
Florida Center for Solid and Hazardous Waste Management Report 01-03, 96 pp, 2001

In addition to greenhouse and pot research results, this report contains case studies of pilot-scale plantings installed to assess the feasibility of full-scale phytoremediation for As, Cu, Cr, and PCP a former wood preserving facility; N and P in reclaimed water; and toluene, benzene, and xylenes at a hydrocarbon spill site.

Adobe PDF LogoPhytoremediation of Dissolved Phase Organic Compounds: Optimal Site Considerations Relative to Field Case Studies
H.R. Compton, G.R. Prince, S.C. Fredericks, and C.D. Gussman.
Remediation Journal 13(3):21-37(2003)

The authors compare studies from the literature and discuss lessons learned five Superfund sites: J-Field, Aberdeen Proving Ground, Edgewood, MD; Edward Sears Property, New Gretna, NJ; Kauffman and Minteer, Jobstown, NJ: Oregon Poplar, Clackamas, OR; and Naples Truck Stop Site, Naples, UT. One is a fuel site and the others have mixed contaminants, predominantly chlorinated organics.

Phytoremediation of Industrial Sludge Using Vegetation-Assisted Dewatering
X. Qiu and R.C. Loehr.
Remediation Journal 13(1):121-136(2003)

A 3-year phytoremediation field pilot study involved the use of plants to enhance sludge dewatering an inactive natural gas-cracking wastewater lagoon. The dewatering was accompanied by contaminant reduction of benzene, toluene, xylenes, and naphthalene concentrations to below the cleanup goals, while the concentration reductions of PAHs with 3 or more ring varied between 30 and 60%, except for dibenz[a,h]anthracene. Longer abstract.

Practical Salinity Management for Leachate Irrigation to Poplar Trees
Smesrud, J.K. G.D. Duvendack, J.M. Obereiner, J.L. Jordahl, and M.F. Madison.
International Journal of Phytoremediation 14(1):26-46(2012)

The Riverbend Landfill in Western Oregon has been employing phytoremediation of landfill leachate since 1993 by using the leachate to irrigate poplar trees. The site has been adaptively managed to control salinity impacts to the tree crop while beneficially utilizing the applied water and nutrients during each growing season. This paper identifies lessons learned during 15 years of successful site management.

Quality Assurance Project Plan: Saginaw Mill Groundwater Monitoring
P.B. Marti.
Washington State Department of Ecology, Publication 05-03-102, 13 pp, 2005

Soils the former Saginaw Mill site in Aberdeen, WA, are contaminated with diesel, heavy-oil-range TPH, and formaldehyde. Formaldehyde also was detected in the groundwater at concentrations above the cleanup level of 1.46 µg/L. In 1999, the University of Washington planted poplar trees on the site as part of a continued phytoremediation-based site cleanup. The 2000 monitoring data showed that formaldehyde concentrations in groundwater had declined to levels near the reporting limit of 20 µg/L. Additional information: (Marti 2007)

Adobe PDF LogoSecond Five-Year Review Report for Tibbetts Road Superfund Site, Town of Barrington, Strafford County, New Hampshire
U.S. EPA Region 1, Boston, MA. 79 pp, 2008

Groundwater monitoring continues the Tibbetts Road Superfund site to assess the effectiveness of the reduction of groundwater contaminants by vacuum-enhanced recovery, phytoremediation, and intrinsic biodegradation. EPA's second 5-year review of the remedy confirms that progress is being made in site cleanup and that the remedies already in place to deal with chlorinated organics, gasoline components, and metals continue to be protective. The levels of organics in the shallow groundwater beneath most areas of historically highest concentrations are now at or near cleanup levels. In 1998, 1,600 poplar trees were installed primarily to lower the water table, decrease infiltration, and slow the groundwater flow. Additional information: U.S. EPA Region 1: Tibbetts Road Superfund Site

Adobe PDF LogoThe Use and Effectiveness of Phytoremediation to Treat Persistent Organic Pollutants
K. Russell. Overview prepared during an internship with U.S. EPA's Office of Superfund Remediation and Technology Innovation, 49 pp, 2005

Adobe PDF LogoUse of Field-Scale Phytotechnology for Chlorinated Solvents, Metals, Explosives and Propellants, and Pesticides
EPA 542-R-05-002, 2005

U.S. EPA collected information from 79 field-scale phytotechnology projects conducted throughout the U.S. and Canada for treatment of soil and groundwater contaminated with chlorinated solvents, metals, explosives and pesticides. This report was compiled to inform readers of the status of these projects and to share lessons learned and practical experiences with field-scale applications of phytotechnology.

Munitions Constituents

Containerized Wetland Bioreactor Evaluated for Perchlorate and Nitrate Degradation
Technology News & Trends, Issue 16, Jan 2005

DOE and Lawrence Livermore National Laboratory designed and constructed an innovative containerized wetland (bioreactor) system that began operation in November 2000 to degrade perchlorate and nitrate biologically under relatively low-flow conditions a remote Site 300 location.

Demonstration Results of Phytoremediation of Explosives-Contaminated Groundwater Using Constructed Wetlands the Milan Army Ammunition Plant, Milan, Tennessee. Vols. I-IV (Phase II Demonstration Results)
F.J. Sikora, R.A. Almond, L.L. Behrends, J.J. Hoagland, D.A. Kelly.
SFIM-AEC-ET-CR-97059, 4 vols, 1998

The reports describe a demonstration of phytoremediation methods to treat explosives contamination in groundwater using a gravel-based subsurface flow wetland and a lagoon-based surface flow wetland.

Phytorestoration the Iowa Army Ammunition Plant
P.L. Thompson, D.D. Moses, and K.M. Howe.
Phytoremediation, S.C. McCutcheon and J.L. Schnoor (eds.).
John Wiley & Sons, ISBN: 9780471394358, 481-496, 2003

The U.S. Army Corps of Engineers constructed the first full-scale treatment wetland to contain and treat residual TNT and RDX contamination the Iowa Army Ammunition Plant (IAAP) following removal of 38,000 kg of explosives and contaminated soil. TNT concentrations were undetectable in surface water or plant tissues 2 years after wetland installation. Concentrations of RDX in wetland surface waters were below 2 g/L and were undetectable in plant tissues during the summer months. After the initial startup period, RDX concentrations in the treatment wetland never exceeded 0.19 mg/L. The cost of constructing, planting, and monitoring the wetland was comparable to that of covering the residual contamination with native topsoil. Longer abstract. Additional information: (Burken 2000)

Petroleum Products

200 Weeks Later: Rhizodegradation of Trimethylbenzenes in Soil a Former Refinery
B.J. Harding, J.D. Spruit, and D.P. Cassidy.
Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2008). Battelle Press, Columbus, OH. ISBN 1-57477-163-9, Paper B-078, 11 pp, 2008

TMBs are recalcitrant mono-aromatic compounds found in crude oil, and they constitute ~40% of C-9 distillation fractions added directly to gasoline. At an abandoned oil refinery site in south-central Michigan in 2003, the effectiveness of plant-assisted biodegradation using both seeded and planted prairie grasses to address TMBs was evaluated in an ex situ pilot study in 45 cubic yard cells. Enhanced rhizodegradation in the test cell was compared to a control (unplanted but tilled or landfarmed) cell. In June 2007, both cells were evaluated for plant diversity (including presence of invasive plants), concentration of contaminants, and microbial activity. TMBs were not detected in the test cell (<1 µg/kg) in 2007 but were present in the control cell 210 µg/kg. Longer abstract.

Comparison of Trees and Grasses for Rhizoremediation of Petroleum Hydrocarbons
Cook, R.L. and D. Hesterberg.
International Journal of Phytoremediation 15:844-860(2013)

This literature review compares the effectiveness of trees and grasses for rhizoremediation of hydrocarbons and notes the advantages of each vegetation type. Grasses were more heavily represented in the literature and therefore demonstrated a wider range of effectiveness; however, the greater biomass and depth of tree roots may have greater potential for promoting environmental conditions that can improve rhizoremediation, such as increased metabolizable organic carbon, oxygen, and water. Little difference overall was discerned between grasses and trees with respect to average reduction of hydrocarbons for studies that compared planted treatments with a control.

Adobe PDF LogoEngineered Phytoremediation of Benzene, GROs, DROs and Other VOCs in Groundwater
Gatliff, E.G., F. Manale, S. Lucas, and M. Siegman.
IPEC 2012: Proceedings of the 19th International Petroleum & BioFuels Environmental Conference, October 29 - November 1, 2012, San Antonio, Texas. 43 slides, 2012

Two phytoremediation pilots were installed in 2007 at sites in central Michigan to assess the potential for engineered phytoremediation to (1) gain hydraulic control of the local groundwater units and (2) remediate groundwater containing elevated concentrations of benzene, dichloropropane, gasoline range organics (GROs), diesel range organics (DROs), and other VOCs. The Root_Sleeve™ liner of the TreeWell® engineered phytoremediation system is designed to treat the groundwater via a bioreactor effect before the groundwater contacts the root system. Despite elevated VOC concentrations, most of the trees realized aggressive and healthy growth, with the few occurrences of phytotoxicity attributed to elevated chloride levels. Five years of monitoring data show progressive reductions in contaminant concentrations (~20% cumulatively) in affected groundwater in the study area.

Engineered Wetland Removes Subsurface Hydrocarbons While Providing Beneficial Reuse
Technology News & Trends, Issue 36, May 2008

British Petroleum is operating an engineered wetland to treat petroleum-contaminated ground water a 300-acre site in Casper, WY. Augmented by a cascading aeration system, the engineered wetland is achieving non-detect concentrations of target compounds such as BTEX while allowing concurrent reuse of the property for commercial and recreational purposes.

Field Demonstration of Rhizosphere-Enhanced Treatment of Organics-Contaminated Soils on Native American Lands with Application to Northern FUD Sites
C.M. Reynolds.

Demonstrations of rhizodegradation of petroleum in surface soils were conducted to assess performance in cold regions.

Adobe PDF LogoLong Term Hydrocarbon Removal Using Treatment Wetlands
Wallace, S., M. Schmidt, and E. Larson.
Society of Petroleum Engineers Annual Technical Conference and Exhibition, 30 October - 2 November 2011, Denver, Colorado. Paper SPE 145797, 10 pp, 2011

Full-scale treatment wetlands were constructed by BP for groundwater remediation in Casper, Wyoming (commissioned in 2003 to treat benzene, BTEX, and gasoline-range organics) and Wellsville, New York (commissioned in 2008 to treat aniline and nitrobenzene). Both treatment systems have been highly effective and have met regulatory compliance objectives. Excursions above non-detect concentrations typically occur during the winter months when water temperatures are at a minimum and the wetlands are partially iced over.

Adobe PDF LogoA Multi-Process Phytoremediation System for Decontamination of Persistent Total Petroleum Hydrocarbons (TPHs) from Soils
X.-D. Huang, Y. El-Alawi, J. Gurska, B.R. Glick, and B.M. Greenberg.
Microchemical Journal 81(1):139-147(2005)

Scientists the University of Waterloo in Canada have developed a multi-process phytoremediation system (MPPS) that combines landfarming (aeration and light exposure), contaminant-degrading bacteria, plant growth-promoting rhizobacteria (PGPR), and growth of contaminant-tolerant tall fescue. Over a 4-month period, application of the MPPS to soil contaminated with oil refinery sludge at ~5% (w/w) TPH achieved an average TPH removal efficiency twice that of land-farming alone, 50% more than bioremediation alone, and 45% more than phytoremediation alone. After a second 4-month period, the MPPS had removed 90% of all TPH fractions from the soil while phytoremediation alone had removed only 50% TPH. The key elements for successful phytoremediation were the use of a plant species able to proliferate in the presence of high levels of contaminants, plus PGPR strains that increased plant tolerance and accelerated plant growth in the heavily contaminated soils. Additional information: (Greenberg et al. 2008Adobe PDF Logo); (Gurska et al. 2009Adobe PDF Logo)

Adobe PDF LogoPhytoremediation of Petroleum Hydrocarbons
A. Van Epps. Compiled during an internship with U.S. EPA's Office of Superfund Remediation and Technology Innovation, 171 pp, 2006

Phytoremediation of a Petroleum-Hydrocarbon Contaminated Shallow Aquifer, Elizabeth City, NC: Planting Methods and Preliminary Results
R.C. Cook, Master's thesis, North Carolina State University. 97 pp, 2008

The goal of the phytoremediation demonstration site the U.S. Coast Guard Support Center former fuel facility is to prevent petroleum contamination (gasoline and diesel and jet fuel) in soil and groundwater from entering the adjacent river. Over 3,000 bare root or unrooted cuttings of hybrid poplars and willows were planted across the 5-acre site in 2006. In addition to contaminant monitoring results, this work details the effects of three different planting methods on tree growth and mortality. Additional information: (Nichols 2009)Adobe PDF Logo; (Cook et al. 2010); (Nichols et al. 2014, Open Access paper)

Using Native Species Superfund Sites: The Tonolli Metals Site Project
R.J. Nadeau, S.C. Fredericks, and J.L. Brown.
Land and Water 46(4):29-32(2002)

After the removal of metals-contaminated soil from the Tonolli Corporation Superfund site, a former smelter, a portion of the site's soil contained highly weathered #4 fuel oil 3,800 ppm. The soil was screened and spread in a 6-in lift covering approximately 3 acres in the northern section of the Tonolli site property, and plant-mediated bioremediation with revegetation was implemented using native warm-season grasses. Three 1-acre native grasslands were established within the treatment area. This paper reports the results with respect to vegetated and unvegetated sites, planting changes, and cost savings.

Additional Information Bibliography

Andersen, R.G., E.C. Booth, L.C. Marr, M.A. Widdowson, and J.T. Novak. 2008. Volatilization and biodegradation of naphthalene in the vadose zone impacted by phytoremediation. Environmental Science & Technology 42(7):2575-2581.

Andersen, R.G. 2006. In Situ Characterization and Quantification of Phytoremediation Removal Mechanisms for Naphthalene at a Creosote-Contaminated Site. Ph.D. dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA.

Booth, E.C. 2005. Direct Volatilization of Naphthalene at a Creosote-Contaminated Site with a Phytoremediation System. Master's thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.

Burken, J.A. 2000. Phytoremediation/wetlands treatment at the Iowa Army Ammunition Plant. Regional Perspectives in Ecology and Environmental Science. McGraw Hill Web site.

Cook, R.L., J.E. Landmeyer, B. Atkinson, J.-P. Messier, and E.G. Nichols. 2010. Field note: Successful establishment of a phytoremediation system at a petroleum hydrocarbon contaminated shallow aquifer: Trends, trials, and tribulations. International Journal of Phytoremediation 12(7):716-732.

Dahlgren, B. 2009. May 2009 Semiannual Report: Needmore Road Landfill Facility, Salisbury, North Carolina. North Carolina Department of Environment and Natural Resources.

DeVita, W.M. and M. Dawson. 2006. Monitoring Environmental Effects at an Established Phytoremediation Site: Phase III. Center for Watershed Science and Education, Univ. of Wisconsin, Stevens Point. WRI#: R/UW-REM-009, GCC#:03-REM-06.

Dinicola, R.S. and R.L. Huffman. 2009. Selected Natural Attenuation Monitoring Data, Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, 2007 and 2008. U.S. Geological Survey Open-File Report 2009-1141.

Dinicola, R.S. and R.L. Huffman. 2012. Biodegradation of Chloroethene Compounds in Groundwater at Operable Unit 1, Naval Undersea Warfare Center, Division Keyport, Washington, 1999-2010. U.S. Geological Survey Scientific Investigations Report 2012-5013.

Ecolotree. 2007. 2006 Year-End Report for the Phytoremediation EBuffer at the Needmore Landfill near Salisbury, North Carolina. Ecolotree Project #2005.15.

Ferro, A.M. and C.E. Tammi. 2007. Irrigation of tree stands with recovered groundwater containing 1,4-dioxane. International Conference on Phytotechnologies in Denver, CO, September 2007: Abstracts.

Ferro, A., C.E. Tammi, J. Hodgen, and J. LaRue. 2005. Treatment of recovered groundwater containing 1,4-dioxane: Year-round phytovolatilization by irrigating stands of deciduous and coniferous trees. The 21st Annual Conference on Contaminated Soils, Sediments and Water, 17-20 October 2005, University of Massachusetts at Amherst: Abstract, p 42..

Greenberg, B. et al. 2008. Successful field and laboratory tests of advanced phytoremediation systems for decontamination of petroleum and salt impacted soils. Proceedings of RemTech 2008.

Gurska, J. et al. 2009. Three Year Field Test of a Plant Growth Promoting Rhizobacteria Enhanced Phytoremediation System at a Land Farm for Treatment of Hydrocarbon Waste. Environmental Science & Technology 43(1):4472-4479.

Hirsh, S.R., H.R. Compton, D.H. Matey, J.G. Wrobel, and W.H. Schneider. 2003. Five-year pilot study: Aberdeen Proving Ground, Maryland. Phytoremediation. Wiley, New York:635-659.

Hitchcock, D.R., C.D. Barton, K.T. Rebel, J. Singer, J.C. Seaman, J.D. Strawbridge, S.J. Riha, and J.I. Blake. 2005. A containment and disposition strategy for tritium-contaminated groundwater at the Savannah River Site, South Carolina, United States. Environmental Geosciences 12(1):17-28.

Hughes, E. and M. Blaylock. 2006. Ferns successfully extract arsenic from soil in Mid-Atlantic climate. Technology News & Trends 24:2-3(May).

Jackson, W.A., L. Martino, S. Hirsh, J. Wrobel, and J.H. Pardue. 2005. Application of a dialysis sampler to monitor phytoremediation processes. Environmental Monitoring and Assessment 107(1-3):155-171.v

Knox, A., D. Dunn, E. Nelson, W. Specht, and J. Seaman. 2004. Wastewater Treatment and Heavy Metals Removal in the A-01 Constructed Wetland: 2003 Report. WSRC-TR-2004-00228.

Knox, A., M. Paller, E. Nelson, W. Specht, and N. Halverson. 2005a. Assessment of Contaminant Distribution and Stability in Sediment of the A-01 Constructed Wetland: 2005 Report. WSRC-TR-2005-00378.

Knox, A.S., D. Dunn, E. Nelson, W. Specht, M. Paller, and J. Seaman. 2005b. Metals retention in constructed wetland sediment. Proceedings from the First International Conference on Environmental Science and Technology, 23-26 January 2005, New Orleans, LA. American Science Press, ISBN: 0-9768853-5-2, 2:289-294.

Lehman, R.W., J.H Rodgers Jr., F.D. Mooney, J.B. Gladden, and J.R. Bell. 2001. Wetlands for industrial wastewater treatment at the savannah river site: a case study. WEFTEC 2001: Water Environment Federation Annual Conference, Atlanta, GA, 13-17 October 2001.

Lehman, R.W., J.H. Rodgers, J.B. Gladden, C. Murray-Gulde, J.F. Bell, and F.D. Mooney. 2002. Wetlands for Industrial Wastewater Treatment at the Savannah River Site. WSRC-MS-2002-00161.

Lewis, A.C. and D.R. Baird. 2005. The effectiveness of phytoremediation at the DOE Portsmouth Gaseous Diffusion Plant. Proceedings of Waste Management 2005, Tucson, Arizona. Paper WM-5132.

Looney, B.B., D.G. Jackson, B.D. Riha, R. Ramirez, L. Whitehurst, and C.A. Eddy-Dilek. 2010. Independent Technical Review of the X-740 Groundwater Remedy, Portsmouth, Ohio: Technical Evaluation and Recommendations. SRNL-STI-2010-00176.

Marr, L.C., E.C. Booth, R.G. Andersen, M.A. Widdowson, and J.T. Novak. 2006. Environmental Science & Technology 40(17):5560-5566.

Marti, P. Saginaw Mill (Aberdeen) Groundwater Monitoring Results, April and August 2006. Washington State Department of Ecology, Publication 07-03-029.

Nelson, E.A., W.L. Specht, J.A. Bowers, and J.B. Gladden. 2002. Constructed Wetlands for Removal of Heavy Metals from NPDES Outfall Effluent. WSRC-MS-2002-00600.

Nelson, E.A. and J.B. Gladden. 2007. Full-Scale Treatment Wetlands for Metal Removal from Industrial Wastewater. WSRC-MS-2007-00058.

Nichols, E.G. 2009. Phytoremediation to Prevent the NPS Discharge of Gasoline Contaminated Ground Water to the Pasquotank River. North Carolina Department of Environment and Natural Resources, Division of Water Quality.

Nichols, E.G., R.L. Cook, J.E. Landmeyer, B. Atkinson, D.R. Malone, G. Shaw, and L. Woods. 2014. Phytoremediation of a petroleum-hydrocarbon contaminated shallow aquifer in Elizabeth City, North Carolina, USA. Remediation Journal 24(2):29-46.

Pitterle, M.T. 2004. Push-Pull Tests to Quantify In-Situ Naphthalene Phytoremediation Rates. Master's thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA.

Prater, P., G. Blount, T. Kmetz, and K. Vangelas. 2013. Forest irrigation of tritiated water: A proven tritiated water management tool. WM2013: Waste Management Conference, 24-28 February 2013, Phoenix, Arizona. 10 pp.

Rebel, K.T., S.J. Riha, J.C. Seaman, and C.D. Barton. 2005. The use of dynamic modeling in assessing tritium phytoremediation. Environmental Geosciences 12(4):243-250.

Rieske, D.E. and A.C. Lewis. 2008. Trichloroethene in tree-core samples collected at the X-749/X-120 phytoremediation area of the Portsmouth Gaseous Diffusion Plant, Piketon, Ohio. Proceedings of the Sixth International Conference on Remediation of Chlorinated and Recalcitrant Compounds (Monterey, CA; May 2008). Battelle Press. Abstract B-079.

Riha, S. and K. Rebel. 2004. Savannah River Site Mixed Waste Management Facility Southwest Plume Tritium Phytoremediation: Evaluating Irrigation Management Strategies Over 25 Years. Technical Report 03-28-R, 15 pp.

Schneider, W.H., S.R. Hirsh, H.R. Compton, A.E. Burgess, and J.G. Wrobel. 2002. Analysis of hydrologic data to evaluate phytoremediation system performance. Proceedings of the Third International Conference on Remediation of Chlorinated and Recalcitrant Compounds. Battelle Press: 2B-26.

Stanhope, A., C.J. Berry, and R.L. Brigmon. 2008. Field Note: Phytoremediation of chlorinated ethenes in seepline sediments: Tree selection. International Journal of Phytoremediation 10(6):529-546.

Waters, L.D. 2003. Relationships between Hybrid Poplar Tree Extractives and Ground Water Contamination at a Phytoremediation Site. Master's thesis, Virginia Polytechnic Institute, 103 pp.

Widdowson, M., L. Marr, and J. Novak. 2007. Mechanisms for phytoremediation of PAH compounds: A long-term field investigation. Geophysical Research Abstracts 9:10373.