EPA/540/R-05/011 

December 2003 

Deployment of Phytotechnology in the 317/319 Area at 

Argonne National Laboratory-East

Innovative Technology Evaluation Report 

National Risk Management Research Laboratory

Office of Research and Development

U.S. Environmental Protection Agency

Cincinnati, Ohio 45224
Notice 

The information in this document has been funded wholly or in part by the U.S. Environmental 

Protection Agency (EPA) in partial fulfillment of Contract Nos. 68-C-00-179 (TO#8) and 68-C5-0036 

(WA#19) with Science Applications International Corporation (SAIC). It has been subject to the 

Agency's peer and administrative review, and it has been approved for publication as an EPA 

document. Mention of trade names of commercial products does not constitute an endorsement or 

recommendation for use. 

ii 
Foreword 

The U.S. Environmental Protection Agency is charged by Congress with protecting the Nation's land, 

air, and water resources. Under a mandate of national environmental laws, the Agency strives to 

formulate and implement actions leading to a compatible balance between human activities and the 

ability of natural systems to support and nurture life. To meet this mandate, EPA's research program 

is providing data and technical support for solving environmental problems today and building a 

science knowledge base necessary to manage our ecological resources wisely, understand how 

pollutants affect our health, and prevent or reduce environmental risks in the future. 

The National Risk Management Research Laboratory (NRMRL) is the Agency's center for 

investigation of technological and management approaches for reducing risks from threats to human 

health and the environment. The focus of the Laboratory's research program is on methods for the 

prevention and control of pollution to air, land, water, and subsurface resources; protection of water 

quality in public water systems; remediation of contaminated sites and ground water; and prevention 

and control of indoor air pollution. The goal of this research effort is to catalyze development and 

implementation of innovative, cost-effective environmental technologies; develop scientific and 

engineering information needed by EPA to support regulatory and policy decisions; and provide 

technical support and information transfer to ensure effective implementation of environmental 

regulations and strategies. 

This publication had been produced as part of the Laboratory's strategic long-term research plan. It 

is published and made available by EPA's Office of Research and Development to assist the user 

community and to link researchers with their clients. 

Sally Gutierrez, Director 

National Risk Management Research Laboratory 

iii 
Abstract 

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 TreeMediation® TreeWell® Treatment System developed by Applied Natural Sciences. 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. A weather station with data logging equipment was installed. ANL-E predicted physical 

effects of the plants on groundwater using a standard hydrological model. The treatment period will 

continue for up to 20 years. 

This Innovative Technology Evaluation Report presents the results from sampling, monitoring, and 

modeling efforts to date. The project has demonstrated success in reducing contaminated 

groundwater flow and taking up contaminants at the source; it also provides insight into the 

techniques that are useful for measuring and predicting the effectiveness of future similar projects. 

iv 
Contents 

Notice ....................................................................... ii

Forward ..................................................................... iii

Abstract .................................................................... iv

Tables ...................................................................... viii

Figures ..................................................................... ix

Acronyms, Abbreviations and Symbols ............................................. x

Acknowledgments ............................................................ xiii

Disclaimer ................................................................... xiv

Executive Summary ............................................................ 1

Section 1 Introduction ...................................................... 5

1.1 The Study Site, Contaminants of Concern, and Potential Remedies . . . 5

1.1.1 The Study Site ...................................... 5

1.1.2 Chlorinated Aliphatic Hydrocarbons ...................... 5

1.1.3 The Fate of CAHs .................................... 6

1.1.4 Tritium ............................................ 6

1.1.5 Limitations of Conventional Treatment Technologies ........ 6

1.1.6 The Case for Phytotechnology .......................... 8

1.2 Brief Technology Description ................................. 9

1.3 Description of SITE Program and Reports ...................... 11

1.4 The SITE Demonstration Program ............................ 12

1.5 Purpose of the Innovative Technology Evaluation Report .......... 12

1.6 Key Contacts ............................................. 12

Section 2 Technology Applications Analysis ................................... 15

2.1 Key Features ............................................. 15

2.2 Operability of the Technology ................................ 15

2.2.1 Site Screening ..................................... 15

2.2.2 Engineering and Installation ........................... 17

2.2.3 Operation and Maintenance ........................... 18

2.2.4 Site Closure ....................................... 19

2.3 Applicable Wastes ......................................... 19

2.4 Availability and Transportability of the Equipment ................. 19

2.5 Materials Handling Requirements ............................. 20

2.6 Site Support Requirements .................................. 20

2.7 Range of Suitable Site Characteristics ......................... 21

2.8 Limitations of the Technology ................................ 21

2.9 Technology Performance versus ARARS ....................... 21

2.9.1 Resource Conservation and Recovery Act ............... 22

2.9.2 Comprehensive Environmental Response, Compensation, 

and Liability Act .................................... 22

v 
Contents (Con’t) 

2.9.3 Clean Water Act .................................... 22

2.9.4 Clean Air Act ...................................... 23

2.9.5 Toxic Substances Control Act ......................... 23

2.9.6 Work Safety and Training ............................. 23

2.9.7 Other Statutes ..................................... 24

Section 3 Economic Analysis ............................................... 27

3.1 Introduction .............................................. 27

3.2 Conclusions .............................................. 27

3.3 Issues and Assumptions .................................... 29

3.3.1 Site Characteristics ................................. 29

3.3.2 Design and Performance Factors ....................... 29

3.3.3 Financial Assumptions ............................... 29

3.4 Basis for Economic Analysis ................................. 29

3.4.1 Inspection/Assessment Develop Monitoring Plan .......... 29

3.4.2 Engineering and Deployment .......................... 30

3.4.3 Non-O&M Cost (FY00-FY02) .......................... 30

3.4.4 O&M Cost (FY99-FY02) .............................. 31

3.4.5 Recurring O&M Cost (FY03-FY19) ..................... 31

3.5 Comparison between DOE Baseline Technology & Phytotechnology . 31

3.5.1 Baseline Approach .................................. 31

3.5.2 Phytotechnology Approach ........................... 31

3.5.3 Technical Comparison ............................... 31

3.5.4 Cost Comparison ................................... 32

Section 4 Treatment Effectiveness ........................................... 33

4.1 Project Overview .......................................... 33

4.2 Detailed Project Description ................................. 34

4.2.1 317/319 Area ...................................... 34

4.2.2 Hydrogeology ...................................... 35

4.2.3 Climatology ........................................ 36

4.2.4 Remedy Selection .................................. 37

4.2.5 Plantation Installation ................................ 37

4.2.6 Monitoring ......................................... 40

4.3 Project Objectives ......................................... 41

4.3.1 Primary Objectives .................................. 41

4.3.2 Non-primary Objectives .............................. 44

4.4 Performance Data ......................................... 46

4.4.1 Primary Objectives .................................. 46

4.4.2 Non-primary Objectives .............................. 55

4.5 Discussion ............................................... 64

4.6 Data Quality Summary ..................................... 66

4.6.1 TCE in Soil ........................................ 66

4.6.2 Target VOCs in Groundwater .......................... 67

4.6.3 Tritium in Groundwater ............................... 67

Section 5 Other Technology Requirements .................................... 70

5.1 Environmental Regulation Requirements ....................... 70

5.2 Personnel Issues .......................................... 70

vi 
Contents (Con’t) 

5.3 Community Acceptance .................................... 71

Section 6 Technology Status ............................................... 72

6.1 Previous Experience ....................................... 72

6.2 Scaling Capabilities ........................................ 72

References Cited ............................................................. 74

vii 
Tables 

1-1 Conventional Treatment Technologies for DNAPL Source Areas ................... 7

1-2 Conventional Treatment Technologies for Dissolved DNAPL Plumes ............... 7

2-1 Potential Federal and State Requirements for a Tree-Based 

Phytoremediation System ................................................ 25

3-1 Cost Estimates for the ANL-E Tree-Based Phytoremediation System .............. 28

3-2 Total Tree Planted Surface Area ........................................... 29

4-1 Maximum 317 Area VOC Concentrations above Applicable Remediation Objectives . . 35

4-2 Maximum 319 Area Tritium/VOC Concentrations above or Equal to Applicable 

Remediation Objectives ................................................. 35

4-3 Transpiration Rates for Instrumented Trees during 2001 Growing Season .......... 47

4-4 Sap Flow Change between 2000 and 2001 .................................. 48

4-5 Mean Target VOC Concentration in Groundwater (mg l-1) ....................... 50

4-6 Mean Tritium Concentration in Groundwater (pCi l-1) ........................... 50

4-7 Water Column Sizes for Sampled Monitoring Wells ............................ 52

4-8 Comparison of Baseline and Final Sample Pairs for French Drain Soils ............ 55

4-9 Mean Groundwater Geochemical Results .................................... 58

4-10 Geochemical Indicator Traits .............................................. 59

4-11 Groundwater Product / Byproduct Ratios .................................... 60

4-12 Selected Groundwater PLFA Results ....................................... 60

4-13 Summary of Soil Geochemical Data ........................................ 62

4-14 Summary of Soil PLFA Results ............................................ 63

viii 
Figures 

1-1 Diagram of the ANS TTTS® ............................................... 10

1-2 317/319 Area Phytosystem ............................................... 11

2-1 Inspecting Livestock prior to Planting ....................................... 18

2-2 Tree Installation at ANL-E ................................................ 20

4-1 Locations of ANL-E and the 317/319 Area ................................... 34

4-2 As-built Drawing of 317/319 Area Plantations ................................. 39

4-3 SITE Demonstration Monitoring Locations ................................... 40

4-4 Relationship between July-October 2001 Sap Flow and Mean Basal Area .......... 48

4-5 Baseline and Final Concentration of Target VOCs ............................. 51

4-6 Mean TCE Concentration in 317 FD ........................................ 54

4-7 ORP Ranges for Various Biochemical Reducing Conditions ..................... 59

4-8 Mean Soil Geochemical Results ........................................... 62

4-9 Well 317181 Water Levels, July 1-5, 2001 ................................... 65

ix 
Acronyms, Abbreviations and Symbols 

ac acre 

ANL-E Argonne National Laboratory-East 

ANS Applied Natural Sciences 

ARARs Applicable or Relevant and Appropriate Regulations 

ASTD Accelerated Site Technology Deployment 

bgs below ground surface 

BSE Baseline Sampling Event 

BTEX Benzene, Toluene, Ethylbenzene, and Xylene o

C Degree Centigrade 

CAA Clean Air Act 

CAHs Chlorinated Aliphatic Hydrocarbons 

CAP-88 Clean Air Act Assessment Package-1988 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CDD Cooling Degree Days 

CFR Code of Federal Regulations 

CLF Chloroform 

cm centimeter 

COE Corps of Engineers 

CSO ANL-E Construction Safety Officer 

CV Coefficient of Variation 

CWA Clean Water Act 

db decibel 

DCA 1,1-Dichloroethane 

DCE cis-1,2-Dichloroethene 

DNAPL Dense Non-Aqueous Phase Liquid 

DO Dissolved Oxygen 

DOC Dissolved Organic Carbon 

DOE U.S. Department of Energy 

EPA U.S. Environmental Protection Agency o

F Degree Fahrenheit 

FD French Drain or French Drain Plantation 

FDCP French Drain Control Plot 

Fe Iron 

FID/ECD Flame Ionization and Election Capture Detection 

FSE Final Sampling Event 

ft foot 

FY Fiscal Year 

g gram 

gal gallon (US) 

GC/CD Gas Chromatography/Conventional Detector 

GDD Growing Degree Day 

x 
Acronyms, Abbreviations and Symbols (cont’d) 

ha hectare 

HASP Health and Safety Plan 

HAP Hazardous Air Pollutant 

HAZWOPER Hazardous Waste Operations and Emergency Response 

HC Hydraulic Control Area 

IEPA Illinois Environmental Protection Agency (IEPA) 

in inch 

ITER Innovative Technology Evaluation Report 

JSA Job Safety Analysis 

kg kilogram 

km kilometer 

L or l liter 

LCS/LCSD Laboratory Control Sample/Laboratory Control Sample Duplicate 

m meter 

mg milligram 

mi standard mile 

mm millimeter 

Mn Manganese 

MS/MSD Matrix Spike/Matrix Spike Duplicates 

MSE Mid-term Sampling Event 

NESHAP National Emission Standards for Hazardous Air Pollutants 

ng nanogram 

NPDES National Pollution Discharge Elimination System 

NPL National Priority List 

NPK Nitrogen, Phosphorous, and Potassium 

NRMRL National Risk Management Research Laboratory 

O&M Operations & Maintenance 

ORP Oxidation Reduction Potential 

OSHA Occupational Safety and Health Administration 

PCBs Polychlorinated Biphenyls 

PCE Tetrachloroethene or Perchloroethene 

pCi picoCurie 

PET Potential Evapotranspiration 

PLFA Phospholipid Fatty Acids 

pmol picomole 

PPE Personal Protective Equipment 

QA/QC Quality Assurance/Quality Control 

r

2 coefficient of determination 

RCRA Resource Conservation and Recovery Act 

RPD Relative Percent Difference 

RSD Relative Standard Deviation 

s second 

SAIC Science Applications International Corporation 

SB Soil Bore 

SITE Superfund Innovative Technology Evaluation Program 

SSI Site Screening Inspection 

SWMU Solid Waste Management Unit 

TCA 1,1,1-Trichloroethane 

TCAA Trichloroacetic Acid 

TCE Trichloroethene 

xi 
Acronyms, Abbreviations and Symbols (cont’d) 

TDP Thermal Dissipation Probe 

TOC Total Organic Carbon 

TSA Technical Systems Audit 

TSCA Toxic Substance Control Act 

USDA United States Department of Agriculture 

ug microgram 

VC Vinyl Chloride 

VOCs Volatile Organic Compounds 

xii 
Acknowledgments 

This report was developed under the direction of Steven Rock, the EPA Technical Project Manager 

for this demonstration. Gratefully acknowledged are the participation and contributions by the ANL-E 

technical and management team, including Cristina Negri, John Quinn, Jim Wozniak, and Ray 

Hinchman (retired). Their tireless efforts were instrumental in making this project a success. 

This report would like to recognize the financial support provided by the EPA and U.S. Department 

of Energy (DOE) Accelerated Site Technology Deployment (ASTD) program, along with the EM-50, 

Subsurface Contaminant Focus Area. 

xiii 
Disclaimer 

Project objectives evaluated in section 4, Treatment Effectiveness, were done so with data generated 

in accordance with the project-specific quality assurance project plan (QAPP), as is customary. 

However, data and information describing other (non-QAPP) technology performance indicators in 

section 4 were produced by ANL-E. Including their measurements and scientific analyses in this 

report helps significantly in forming a more complete picture of the behavior of this technology to date 

and identifying important operating trends that may manifest more fully in future years. 

The methods and materials used by ANL-E are summarized in section 4 so that the validity of the 

measurements and scientific conclusions drawn therefrom may be assessed by the reader. 

xiv 
EXECUTIVE SUMMARY 

Introduction 

The Argonne National Laboratory-East (ANL-E) is a Department of Energy (DOE) research and development laboratory 

that performs a variety of research in the basic energy and related sciences (i.e., physical, chemical, material, computer, 

nuclear, biomedical, and environmental) and serves as an important engineering center for the study of nuclear and nonnuclear energy sources. ANL-E maintains an active and robust environmental protection program that supports its policy 

of protecting the public, employees, and the environment from harm that could be caused by ANL-E activities, and of 

reducing environmental impacts to the greatest degree practicable. 

Among its environmental restoration duties, ANL-E is managing some 50 cleanup projects. Seven of the projects are 

located in what is referred to in this document as the 317/319 Area at ANL-E. It is located on the extreme southern end 

of the ANL-E site, immediately adjacent to the DuPage County Waterfall Glen Forest Preserve, an area used for public 

recreation and as a nature preserve. The principal environmental concern in the 317/319 Area is related to the presence 

of several volatile organic compounds (VOCs) in the soil and groundwater and low levels of tritium in the groundwater 

beneath and downgradient of the site. Several interim actions have already been implemented to reduce the VOC and 

tritium releases from this area; however, additional remedial actions are ongoing which should further restore the site. 

This report discusses the accomplishments of a phytotechnology system deployed by ANL-E in the 317/319 Area to reduce 

the risks from the VOCs and tritium. Phytotechnology is a proven yet innovative remediation technology, which in this case 

is intended to improve the rate and effectiveness, while decreasing the overall cost, of the planned cleanup of the site. 

Phytotechnology relies on the natural process by which woody and herbaceous plants extract pore water and entrained 

chemical substances from subsurface soils and transpire them into the atmosphere. Degradation of VOCs also takes place 

in the zone of chemical and biological activity immediately surrounding the plant root system. Because of its lower 

deployment costs, phytotechnology is being applied in a more extensive and integrated fashion across the entire 317/319 

Area than would be possible if the baseline approach (capping/extraction wells) were used. 

Activities 

During June and July 1999, ANL-E installed stands of hybrid poplars and hybrid willows and a supplemental ground cover 

of herbaceous plants with the following objectives: 

• Hydraulically contain the VOC and tritium plumes south of the 317 Area French Drain and 319 Area Landfill 

• Continue the remediation of residual VOCs within the 317 Area French Drain 

• Minimize water infiltration into the 317 Area French Drain soils and stabilize the surface to prevent erosion, runoff, and 

downstream sedimentation. 

Earlier in 1999, the U.S. Environmental Protection Agency (EPA) expressed an interest in participating with DOE in this 

study and subsequently included it as a demonstration project under the National Risk Management Research Laboratory 

(NRMRL) Superfund Innovative Technology Evaluation program (SITE). ANL-E anticipates an operating period for the 

phytotechnology deployment of up to 20 years; SITE’s involvement covers the first three years of operations, from July 

1999 through September 2001. During the program kick-off meeting held on April 7, 1999, specific scientific and 

xv 
engineering project objectives were discussed, and tasks designed to generate the data required to evaluate those 

objectives were divided between ANL-E and EPA. 

Monitoring activities during the demonstration included the following: 

• Groundwater Containment 

• Groundwater Contaminant Removal 

• Soil Contaminant Removal 

• Contaminant Uptake and Degradation in Plant Tissue 

• Geochemical and Microbial Indices of Reductive Dechlorination 

• Modeling and Confirming Water Use and Hydraulic Control 

• Health and Growth of the Planted System 

The details on collection methods and evaluation results are presented in section 4. 

Discussion 

The phytotechnologies deployed at ANL-E are supplementary to and intended to eventually replace an existing pump-andtreat system. As the trees completed their third growing season in the field (2001), a significant amount of information had 

been collected to assess their performance at achieving the remedial objectives. From this data, the young plantations 

appear to have begun to influence the cleanup area. The deep-planted trees have tapped into the lower saturated zone 

and are consuming contaminated water. Degradation of volatile organics from the source area soil is occurring in the 

plants, and the rhizosphere is moving toward conditions that are capable of supporting reductive dechlorination. In ground 

water, pollutants are being removed (tritium) or degraded (VOCs) in some areas of the contaminated groundwater plumes. 

Overall, less contamination is reaching the extraction well system than before the plants were installed. 

Probably the key remediation mechanism of this planted system is the interception and removal of water from the impacted 

aquifer (i.e. phytostabilization). Consequently, the magnitude of transpiration is one of the most important monitoring 

parameters: transpiration rates for the trees at the site provide information for evaluating current water removal as well 

as predicting future water usage. Quantified sapflow rates were used to estimate transpiration. Data show that maximum 

sapflow rates determined during the 2001 growing season are still below the plants’ potential as estimated by the hydraulic 

flux at baseline. However, the year-to-year increase in rates suggests that across the plantation water use is closing the 

gap. These data complement others derived from the recording of continuous groundwater elevation at the site, which 

shows diurnal fluctuations of hydraulic heads in correspondence with elevated daily solar radiation (transpiration) during 

the vegetative season. 

Multiple lines of evidence are often needed to demonstrate biodegradation processes at contaminated sites. The lines 

of evidence used to examine biodegradation for this project include (1) detection of TCE and its degradation products in 

tree tissue in the 317 FD; (2) groundwater chemical data that indicate decreasing concentrations of target VOCs and 

increasing concentrations of degradation byproducts (3) geochemical data that indicate depletion of electron donors and 

acceptors; and (4) laboratory microbiological data that indicate the bacteria present at a site can degrade contaminants. 

Tissue analysis of willows growing at the contaminated source area indicate that TCE and PCE are taken up by the trees 

in measurable amounts, and that at least a portion of the transported contaminants is degraded in the leaf. The 

intermediate degradation product, TCAA, appears to be subsequently degraded further in the leaf litter to background 

levels. 

TCE and TCA and their degradation byproducts are seen at nearly all groundwater wells throughout the study area, 

implying that microbial attenuation of some form has occurred. In a number of cases monitoring data are unclear about 

where or how degradation byproducts were formed, and at other locations VOC, geochemical, and biological indicators 

suggest that reductive dechlorination is ongoing. 

xvi 
Source area soils, which may have been aerated as a result of plant installation, have lost much of their initial aerobic 

nature. Obligate-anaerobic, iron and sulfate-reducing bacteria have established colonies across the 317 FD, and there 

appears to be a particularly strong anaerobic character building in segments of the source area where contaminant levels 

are greatest. 

After enduring a transplant shock and below-optimal growth conditions during the first two years in the field, the trees grew 

at faster rates in 2001. Their increased size is reflected in increased transpiration rates, and presumably larger/longer root 

systems and enhanced rhizosphere to better influence contaminant reduction and hydraulic control. Modeling based on 

data collected during the first three years of the project predicts full containment of the 317 plume, and significant 

containment of the 319 plume. Figure ES-1 is a time-lapse compilation of a portion of the 317/319 Area collected at 

discrete periods during the course of the demonstration. 

Figure ES-1. Hybrid Poplar Growth in 317/319 Area. 

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xviii
SECTION 1

INTRODUCTION

This section provides a discussion of the origin and need for remediation of the study site, background on the analytes of 

concern, a description of phytotechnology, a summary of the Superfund Innovative Technology Evaluation (SITE) Program, 

and a statement regarding the purpose of this Innovative Technology Evaluation Report (ITER). For additional information 

about the SITE Program visit the U.S. Environmental Protection Agency (EPA) SITE Program web page at 

http://www.epa.gov/ORD/SITE/. For information on this SITE project and the technology involved, key contacts are listed 

at the end of this section. 

1.1 The Study Site, Contaminants of Concern, and Potential Remedies 

1.1.1 The Study Site 

The 317/319 Area at ANL-E covers a surface area of approximately two hectares (five acres) and contains several release 

sites used in the past to dispose of solid and liquid waste from various laboratory activities. Consequently, solvents such 

as trichloroethene (TCE), perchloroethene (PCE), and others and tritium have been detected at soil and groundwater 

monitoring points throughout the 317/319 Area and in adjacent properties. Several interim actions have been completed 

at the site, and the functional requirements for the final remedial actions in the 317/319 Area are to (1) prevent the release 

of soil contamination to groundwater, (2) minimize the offsite migration of groundwater containing VOCs and tritium from 

source areas, and (3) minimize the release of contaminants to storm water runoff. 

The DOE funded ANL-E to deploy a phytotechnology-based system across the site instead of a traditional pump-and-treat 

remedy on the assumption that phytotechnology is more cost effective and better suited to the complex stratigraphy 

underlying the area than the combination of mechanical extraction wells (currently removing groundwater as an interim 

measure) and an asphalt cap to achieve long-term objectives. 

Turn to section 4.1 for a detailed description of the 317/319 Area and 4.2.4 for information on previous remedial actions 

taken. 

1.1.2 Chlorinated Aliphatic Hydrocarbons 

TCE, PCE, and other similar chemicals are from a chemical group known as chlorinated aliphatic hydrocarbons (CAHs). 

For decades these man-made compounds were used at ANL-E for purposes ranging from equipment degreasing to 

laboratory extraction solvents. Through intentional and unintentional releases at facilities nationwide, CAHs are now 

ubiquitous in the environment and include ten of the 25 most common pollutants found in groundwater (NRC, 1994). 

Because they have high specific gravity and low water solubility, CAHs migrate down through the subsurface soil as dense 

nonaqueous-phase liquids (DNAPLs) and form pools at the bottom of aquifers. These DNAPL pools act as continual 

sources of groundwater contamination and are often mobile and difficult to locate or gauge their size. In the vadose zone 

(soil above the water table), CAHs can commingle with soil pore water and volatilize into the soil gas. It is often the case 

that CAHs move upward and laterally in the subsurface and increase or re-distribute the area of the original release 

(Russell et al., 1992). These characteristics have been observed or suspected at the 317/319 Area. 

v 
1.1.3 The Fate of CAHs 

The fate of CAHs in groundwater has been the subject of considerable investigation. Research has shown that many of 

these chemicals can naturally attenuate by either non-destructive or destructive means (Chapelle, 2000). Non-destructive 

mechanisms include dilution through recharge, sorption, and hydrodynamic dispersion (EPA, 1998) as well as diffusion 

into micropores and entrapment in immobile groundwater zones (NRC, 1997). Among the destructive attenuation 

mechanisms, biological degradation is the most important (EPA, 1998). 

EPA (1998) reports that many laboratory and field studies have demonstrated CAHs are biodegradable naturally under 

three different processes: (1) CAHs as electron acceptors (reductive dehalogenation); (2) CAHs as electron donors 

(aerobic respiration); and (3) cometabolism, where degradation of CAHs is fortuitous and of no benefit to the 

microorganism. One or all of these processes may occur at a given site. 

The most significant of these processes for highly chlorinated (i.e. highly oxidized) CAHs is reductive dehalogenation. 

Reductive dehalogenation is a reduction-oxidation (redox) reaction where a highly chlorinated CAH, e.g. PCE, is reduced 

by accepting electrons released during the metabolism (oxidation) of organic food sources by methanogenic bacteria. A 

chlorine atom is replaced on the molecule by electrons coupled to a hydrogen atom, which results in the transformation 

of PCE to TCE. The process can repeat itself with TCE to produce dichloroethene isomers, of which cis-1,2-dichloroethene 

(DCE) is the most commonly produced under these conditions (Bouwer, 1994). The rate of reductive dehalogenation 

decreases as the degree of chlorination decreases, so further degradation of DCE to vinyl chloride, while possible, is 

usually slow. 

To a lesser extent, direct aerobic respiration and cometabolism have been observed as natural attenuation mechanisms. 

McCarty and Semprini (1994) describe investigations in which vinyl chloride (VC) and 1,2-dichloroethane (DCA) served 

as primary substrates. In contrast to reductive dehalogenation where the most chlorinated CAHs are preferred, aerobic 

respiration can utilize only the least chlorinated (i.e. least oxidized) of the CAH compounds. Murray and Richardson (1993) 

have reported that under aerobic conditions chlorinated ethenes, with the exception of PCE, are susceptible to cometabolic 

degradation. During cometabolism, CAH compounds are coincidentally transformed by bacteria as they consume other 

organic compounds to meet their energy requirements. Vogel (1994) further elaborates that the rate of cometabolism 

increases as the degree of chlorination decreases. 

1.1.4 Tritium 

The other contaminant of concern for this project is tritium. Tritium is a radioactive form (radioactive isotope) of hydrogen. 

The normal hydrogen atom (also called protium) has one proton and one electron and accounts for 99.985% of natural 

hydrogen. Like hydrogen, tritium also has one proton and one electron, but differs because it also has two neutrons, which 

give it too much energy to be stable. Each atom of tritium releases its excess energy in the form of a low energy beta 

particle, whereupon the atom becomes a stable isotope of helium. This release of excess energy is called radioactive 

decay. Tritium has a radioactive half-life of about 12.3 years, which means that in that time half of the original tritium atoms 

will have decayed to helium (SRS, 2002). 

Tritium is constantly produced both by natural processes (the interaction of cosmic rays with the atmosphere) and by 

human-made processes. Tritium is used in a wide variety of consumer products such as illuminated watches, thermostat 

dials, and exit signs. Both the natural and human sources contribute to a worldwide background level of tritium. 

Because tritium is simply a hydrogen atom with two neutrons instead of none, its chemical behavior is essentially the same 

as regular hydrogen. In water, tritium isotopes very easily replace one or both of the normal hydrogen atoms. This 

behavior presents a unique cleanup challenge because, on a large scale, there is no technology that removes or separates 

tritium from groundwater (SRS, 2002). 

vi 
1.1.5 Limitations of Conventional Treatment Technologies 

The conventional strategies of excavating soil and pumping and treating contaminated groundwater are generally 

unsatisfactory at restoring DNAPL-contaminated sites (Pankow and Cherry, 1996). A 1994 National Research Council 

study of conventional groundwater cleanup systems at 77 contaminated sites determined that cleanup levels had been 

achieved at only eight of the sites and full realization of cleanup goals was highly unlikely with the in-place technologies 

at 34 of the 77 sites (NRC, 1997). Tables 1-1 and 1-2 list conventional technologies used to treat source areas and 

groundwater plumes and summarize their limitations. 

Although the weaknesses of these technologies have become increasingly clear, their use is widespread. A U.S. 

Environmental Protection Agency (EPA) status report observed that as of 1996 conventional methods were in operation 

at 93% of Superfund sites (EPA, 1996a). 

Table 1-1. Conventional Treatment Technologies for DNAPL Source Areas 

Technology Mechanism Limitations 

Steam Volatilization, 

mobilization 

Must be able to control steam flow and to heat units to appropriate temperature. 

Heterogeneity may increase treatment times and produce tailing. Must consider 

implications of DNAPL mobilization. 

Surfactants Dissolution, 

mobilization 

Must be able to establish hydraulic control. Heterogeneity may increase 

treatment time and produce tailing. Must consider implications of DNAPL 

mobilization. 

Solvents Dissolution, 

mobilization 

Must be able to establish hydraulic control. Heterogeneity may increase 

treatment time and produce tailing. Must consider implications of DNAPL 

mobilization. 

Insitu oxidation Chemical reaction Must be able to deliver adequate reagent to source zone. Heterogeneity may 

increase treatment time and produce tailing. Reaction with other compounds may 

reduce effectiveness 

Insitu vitrification Thermal 

decomposition 

Soil must produce appropriate melt. Vapor emissions must be controlled. Depth 

limited to 10 m (30 ft). 

Soil vapor extraction Volatilization Must be able to induce adequate air flow through entire source zone. 

Heterogeneity and high water content may limit effectiveness. 

Air sparging Volatilization Must be able to induce adequate air flow through entire source zone. 

Heterogeneity may limit effectiveness. Contaminants must be volatile at 

groundwater temperature, generally less than 15o

 C (59o F). 

Electrical heating Volatilization Volatilized contaminants must be removed by another technology 

(typically vapor extraction or steam). Permeability must be sufficient for 

vapor flow. 

vii 
Table 1-2. Conventional Treatment Technologies for Dissolved DNAPL Plumes 

Technology Mechanism Limitations 

In-well stripping Volatilization Treatment zone depends on groundwater flow pattern established. 

Reactive barriers Dechlorination Treats only aqueous phase. Wall must intercept entire plume. Specific 

limitations attached to barrier type. 

Electrokinetic 

systems 

Electrically induced 

mobilization 

Applications to DNAPL not well established. Must be coupled with technology for 

destruction or removal of contamination. 

Physical barriers Containment Limitations vary with barrier type. If not keyed into impermeable unit at 

base, system will be open and contamination will not be contained. 

Note: Tables 1-1 and 1-2 adapted from NRC, 1999. 

1.1.6 The Case for Phytotechnology 

1.1.6.1 Technical Characteristics 

Phytotechnology can be defined as the purposeful use of green plants to affect pollutants in soil, sediment, surface water, 

and ground water. Phytotechnologies have been reported successful in laboratory, bench-scale, or full scale projects 

involving a variety of contaminants (ITRC, 2001): 

• Organic contaminants, including petroleum hydrocarbons, gas condensates, crude oil, chlorinated compounds, 

pesticides, PCBs, and explosive compounds. 

• Inorganic contaminants, including salts, heavy metals, metalloids, nutrients, and radioactive materials. 

Six different plant-facilitated processes have been recognized as contributing to phytotechnology success. These 

processes are as follows: 

• Phytoaccumulation, referring to a process where plant roots uptake and translocate contaminants (typically metals and 

radionuclides) from their roots to their above-ground biomass where the contaminants are concentrated and removed 

by harvesting the plants 

• Rhizostabilization, which is a process whereby contaminants (typically metals) are sorbed onto plant roots and 

therefore not likely to migrate 

• Rhizodegradation, which involves the complex interaction of roots, root exudates, and the surrounding soil and 

microbial community, and how these elements combine to break down contaminants, (typically organics) in situ 

• Phytodegradation, which includes processes occurring inside the plant which can degrade contaminants, (usually 

organics) 

• Phytovolatilization, referring to the process whereby contaminants are extracted from soil or ground water and then 

transpired into the atmosphere (typically organics) 

• Phytostabilization, which describes how certain plants with high water demand (woody plants typically) can slow or 

reverse ground water flow paths thereby containing contaminated groundwater plumes. 

Phytotechnology has been suggested as a strategy for treating CAH contamination. In the case of TCE (one of the 

contaminants of concern at the ANL-E site), hybrid poplars (Populus spp.) have been the subject of many lab and fieldscale investigations (Chappell, 1997). These investigations propose several of the plant-facilitated processes described 

above as reasons why poplars are considered useful for treating TCE in soil and groundwater: 

• Rhizodegradation (I) - Poplar root systems can break down TCE in soil by exuding certain ex planta enzymes (those 

released by the plant into the root zone). These include dehalogenases and laccases, enzymes which have important 

natural functions and have been shown to help degrade TCE and other CAHs (Negri et al., 1998). 

• Rhizodegradation (II) - TCE degradation has been observed in soil with increased microbial activity. Roots exude 

complex secretions containing carbohydrates that feed and stimulate the microorganisms and natural chelating agents 

viii 
that help mobilize both nutrients and contaminants (Negri et al., 1998). Significant mineralization of TCE has been 

documented in slurries of rhizosphere soil collected from a former solvent disposal site (Walton and Anderson, in 

Cunningham et al., 1996). 

• Phytodegradation - Poplars can take up TCE and metabolize it into benign end products. In one study, xenic (sterile, 

homogenous) cell cultures were studied to examine the consequences of the metabolic activity of a poplar hybrid 

(Populus trichocarpa x deltoides, H 11-11) in the absence of soil, mycorrhizal flora, or microbial activity. The cells were 

incubated with TCE and later extracted and analyzed for metabolites. Chloral, trichloroacetate, dichloroacetate, and 

trichloroethanol were detected in the extracts. These compounds are known physiological oxidative metabolites of 

TCE; thus, researchers suspect that similar oxygenase activities exist in cells of this and other poplars (Newman et 

al., 1997). 

• Phytostabilization - Poplars can provide hydraulic control of a contaminated plume until plant-stimulated activity, natural 

attenuation, or other processes degrade contaminants. PopIars and many other members of the willow family 

(Salicaceae) are phreatophytes, meaning their deep roots draw water from or near the water table. These trees are 

also known as fast growers and must transpire a substantial amount of moisture to meet their metabolic needs. These 

characteristics make poplars ideally suited to provide hydraulic control of groundwater. 

In addition to the plant-facilitated mechanisms described above, it is estimated that a typical poplar plantation can produce 

as much as 120,000 km (75,000 mi) of fine roots per acre (EPA, 2000). Such a density allows roots more complete 

coverage of a waste site, particularly in a heterogeneous subsurface that limits the effectiveness of conventional 

technologies. 

1.1.6.2 Other Potential Advantages 

Beyond potential technical advantages, phytotechnology is an attractive strategy for several reasons. It is considered less 

expensive than conventional methods. Estimated costs are as low as 10% to 50% of other methods such as pump and 

treat (Rock and Sayre, 1998; Chappell, 1997). Phytotechnology is also viewed as an environment-friendly concept. 

Vegetation is a "natural" part of ecosystems, and tree plantations have a park-like aesthetic and provide shade, habitat, 

and windbreaks (Lay, 1999). Implementation may be less intrusive than the installation of mechanical equipment and 

utilities associated with conventional technologies. 

1.1.6.3 Potential Regulatory Acceptability 

Due to the potential utility of phytotechnology and its lower estimated costs, there is a great deal of interest on the part of 

site owners, managers, and their consultants and contractors in applying this technology to their sites. Balanced against 

this prospect are questions regarding the true rate and extent of cleanup using this technology, as well as other associated 

risk concerns. Specific regulatory standards on the efficacy and potential risks for phytoremediation have not been 

developed, and installations are currently approved on a site-by-site basis (Rock and Sayre, 1998). 

One indication that a technique will be accepted for treatment of a given site is a track record of prior successful 

applications on similar sites. Because it is relatively new, phytotechnology does not have a long history of completed 

cleanups or site closures. Past results of studies done in greenhouses and on field test plots in different locales can be 

used generally to show proof of concept. Similar type studies performed on soil or water from the site can confirm the 

efficacy of site-specific treatment (Rock and Sayre, 1998). 

1.2 Brief Technology Description 

The primary technical challenge at the 317/319 Area is reaching polluted soil and groundwater as deep as 30 ft (9 m) below 

ground surface (bgs). Root-to-contaminant contact is the key to phytotechnology success; therefore, the depth to the 

affected media has to be shallow enough for the roots reach it. In the case of ground water, roots to must be able to 

develop to the capillary fringe, the zone above the aquifer where water is drawn upward by the capillary action of soil 

micropores. Given these limitations, phytosystems (prior to 1999) generally targeted affected media at depths of 20 ft (6 

m) or less (EPA, 2001); however, Applied Natural Sciences, Inc (ANS), Hamilton, OH, the contractor hired by ANL-E to 

plan and install the system in the 317/319 Area, developed planting techniques that purportedly extend the treatment range 

to over 30 ft (9 m) bgs. 

ix 
According to ANS, the TreeMediation® TreeWell® Treatment System (TTTS® ) creates a permeable zone to promote and 

direct root growth by developing a column through the vertical extent of the affected media (see Figure 1-1). The existence 

of the column provides a preferential pathway for roots to develop either (1) throughout the area of contaminated soil, or, 

if the column is lined to prevent outward root penetration, (2) down into the capillary fringe of the contaminated aquifer. 

Figure 1-1. Diagram of the ANS TTTS® 

x 
Figure 1-2. 317/319 Area Phytosystem 

The column also allows for ready upflow of 

the water to the root system. The installation depth of the root ball mass can 

be varied to better target subsurface soil 

horizons or decrease the distance and 

time the roots must travel to reach ground 

water. 

During the summer of 1999, approximately 800 hybrid poplars and hybrid 

willows were planted using the ANS 

TTTS® in and downgradient of the 317/319 

Area with the goal of intercepting the flow 

of ground water and preventing the offsite 

migration of pollutants. In the upgradient 

source area (i.e., 317 Area French Drain) 

hybrid willow trees were planted in a 

manner such that their roots could freely 

explore the contaminated soil and take up 

pore water and entrained chemicals. A 

vegetative cover of herbaceous plants was 

seeded among the trees to control soil erosion and minimize water infiltration. 

Figure 1-2 is an aerial view of the 317/319 Area shortly after the phytosystem was installed. Turn to section 4.2.5 for a 

detailed description of the specific planting techniques used at the 317/319 Area. 

1.3 Description of the SITE Program and Reports 

The SITE Program is a formal program established by EPA's Office of Solid Waste and Emergency Response (OSWER) 

and Office of Research and Development (ORD) in response to the Superfund Amendments and Reauthorization Act of 

1986 (SARA). The SITE Program promotes the development, demonstration, and use of new or innovative tech-nologies 

to clean up Superfund sites across the country. 

The SITE Program's primary purpose is to maximize the use of alternatives in cleaning hazardous waste sites by 

encouraging the development and demonstration of new, innovative treatment and monitoring technologies. It consists 

of three major elements discussed below: 

• the Demonstration Program, 

• the Monitoring and Measuring Technologies Program, and 

• the Technology Transfer Program. 

The objective of the Demonstration Program is to develop reliable performance and cost data on innovative technologies 

so that potential users can assess the technology's site-specific applicability. Technologies evaluated are either available 

commercially or close to being available for full-scale remediation of Superfund sites. SITE demonstrations usually are 

conducted on hazardous waste sites under conditions that closely simulate full-scale remediation conditions, thus assuring 

the usefulness and reliability of information collected. Data collected are used to assess: (1) the performance of the 

technology, (2) the potential need for pre- and post-treatment processing of wastes, (3) potential operating problems, and 

(4) the approximate costs. The demonstrations also provide opportunities to evaluate the long-term risks, capital and O&M 

costs associated with full-scale application of the subject technology, and limitations of the technology. 

Existing technologies and new technologies and test procedures that improve field monitoring and site characterizations 

are identified in the Monitoring and Measurement Technologies Program. New technologies that provide faster, more costeffective contamination and site assessment data are supported by this program. The Monitoring and Measurement 

Technologies Program also formulates the protocols and standard operating procedures for demonstrating methods and 

equipment. 

xi 
The Technology Transfer Program disseminates technical information on innovative technologies in the Demonstration, 

and the Monitoring and Measurement Technologies Programs through various activities. These activities increase the 

awareness and promote the use of innovative technologies for assessment and remediation at Superfund sites. The goal 

of technology transfer activities is to develop interactive communication among individuals requiring up-to-date technical 

information. 

1.4 The SITE Demonstration Program 

Technologies are selected for the SITE Demonstration Program through annual requests for proposals. ORD staff review 

the proposals to determine which technologies show the most promise for use at Superfund sites. Technologies chosen 

must be at the pilot- or full-scale stage, must be innovative, and must have some advantage over existing technologies. 

Mobile and in-situ technologies are of particular interest. 

Once EPA has accepted a proposal, cooperative agreements between EPA and the developer establish responsibilities 

for conducting the demonstrations and evaluating the technology. The developer is responsible for demonstrating the 

technology at the selected site and is expected to pay any costs for transport, operations, and removal of the equipment. 

EPA is responsible for project planning, sampling and analysis, quality assurance and quality control, preparing reports, 

disseminating information, and transporting and disposing of treated waste materials. 

At the conclusion of a SITE demonstration, EPA prepares an Innovative Technology Evaluation Report (ITER), Technology 

Capsule, and Demonstration Bulletin. These reports evaluate all available information on the technology and analyze its 

overall applicability to other site characteristics, waste types, and waste matrices. Testing procedures, performance and 

cost data, and quality assurance and quality standards are also presented. 

1.5 Purpose of the Innovative Technology Evaluation Report 

This ITER provides information on the deployment of phytoremediation at the 317/319 Area of ANL-E and includes a 

comprehensive description of the demonstration and its results. The ITER is intended for use by EPA remedial project 

managers, EPA on-scene coordinators, contractors, and other decision makers in implementing specific remedial actions. 

The ITER is designed to aid decision makers in further evaluating specific technologies when considering applicable 

options for particular cleanup operations. This report represents a critical step in the development and commercialization 

of a treatment technology. 

To encourage the general use of demonstrated technologies, EPA provides information regarding the applicability of each 

technology to specific sites and wastes. The ITER includes information on cost and performance, particularly as eval-uated 

during the demonstration. It also discusses advantages, disadvantages, and limitations of the technology. 

Each SITE demonstration evaluates the performance of a technology in treating a specific waste or combination of wastes 

in a specific environmental setting. The characteristics of other sites likely differ from the characteristics of the site tested. 

Therefore, a successful field demonstration of a technology at one site does not necessarily ensure that it will be applicable 

at other sites. Data from the field demonstration may require extrapolation for estimating the operating ranges in which 

the technology will perform satisfactorily. Only limited conclusions can be drawn from a single field demonstration. 

1.6 Key Contacts 

Additional information on the ANL-E field demonstration and the SITE Program can be obtained from the following sources: 

This SITE Demonstration 

Steven Rock 

National Risk Management Research Laboratory 

U.S. Environmental Protection Agency 

5995 Center Hill Avenue 

Cincinnati, OH 45224 

Tel: (513) 569-7149 

xii 
Fax: (513) 569-7879 

Email: rock.steven@epa.gov 

ANL-E Phytotechnology System 

M. Cristina Negri 

Argonne National Laboratory 

9700 South Cass Avenue 

Building 362 

Argonne, IL 60439 

Tel: 630-252-9662 

Email: Negri@anl.gov 

James Wozniak 

Argonne National Laboratory 

9700 South Cass Avenue 

Building 331 

Argonne, IL 60439 

Tel: 630-252-6306 

Email: Jwozniak@anl.gov 

The SITE Program 

Annette Gatchett 

National Risk Management Research Laboratory 

U.S. Environmental Protection Agency 

26 West Martin Luther King Drive 

Cincinnati, OH 45268 

Tel: (513) 569-7697 

Email: gatchett.annette@epa.gov 

Information on the SITE Program also is available through the following on-line information clearinghouses: 

C The Hazardous Waste Clean-up Information Web Site provides information about innovative treatment 

technologies to the hazardous waste community. It describes programs, organizations, publications and other tools 

for federal and state personnel, consulting engineers, technology developers and vendors, remediation 

contractors, researchers, community groups and individual citizens. CLU-In may be accessed at http://www.cluin.org/. 

C EPA REmediation And CHaracterization Innovative Technologies (REACH IT) is a system that lets environmental 

professionals use the power of the Internet to search, view, download and print information about innovative 

remediation and characterization technologies. EPA REACH IT will give you information about more than 650 

service providers that offer almost 1,300 remediation technologies and more than 150 characterization 

technologies. EPA REACH IT combines information from three established EPA databases, the Vendor 

Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and 

Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give 

users access to comprehensive information about treatment and characterization technologies and their 

applications. used and the service providers that offer them. EPA REACH IT can be accessed at 

http://www.epareachit.org/. 

Technical reports may be obtained by contacting the Center for Environmental Research Information (CERI), 26 West 

Martin Luther King Drive in Cincinnati, Ohio, 45268 at 1-800-490-9198 or (513) 569-7562. 

xiii 
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xiv
SECTION 2

TECHNOLOGY APPLICATIONS ANALYSIS

This section addresses the applicability of the phytotechnology system deployed by ANL-E at its 317/319 Area to other 

sites. This analysis is general in nature and intended primarily to highlight features of the ANL-E system and call out other 

issues to investigate further by readers considering a similar remedy. The information presented in this section is based 

upon the results of this SITE project and research conducted by others. A concise overview of the ANL-E phytosystem 

is on the ANL-E website at www.es.anl.gov/htmls/cbt10-phyto.html. 

2.1 Key Features 

Some of the key features of the ANL-E deployment include the following: 

• Proprietary ANS TTTS® rooting techniques designed to reach ground water 30 ft (9 m) bgs. See section 1.2 for 

more details on the ANS TTTS® . 

• Application designed to reduce or control the movement of contaminants until reductive dehalogenation, natural 

attenuation or other processes can reduce contaminant concentrations consistent with site goals. 

• Full scale, with more than 800 trees. Hybrid poplars (600-plus) and hybrid willows (200-plus) planted in several 

engineered, strategically positioned plantations. (Turn to section 4.2.5 for an “as-built” map of the ANL-E 

phytosystem.) 

• Trees of the Salicaceae family, poplar and willow, have high growth and transpiration rates. They are also 

phreatophytes (literally, “water-loving tree”). Phreatophytes are plants whose roots generally extend downward 

to the water table and feed on the capillary fringe. The combination of fast growth, large water demand, and the 

need to take in ground water makes poplars and willows ideal candidates for phytostabilization applications. 

• Poplars and willows have a known, demonstrated ability to transform a variety of chlorinated VOCs, including TCE 

and PCE. 

• Planting scheme (i.e., various depths, lined/unlined tree wells) promotes contact with soil pollutants in 317 Area 

French Drain and fast root growth to the water table in hydraulic control areas. 

• 317 Area French Drain area seeded with a mix of legumes and grasses to minimize water infiltration and stabilize 

the soil. 

• Eight-foot tall security encircling entire study area; radiologically-contaminated portion of site is access-restricted. 

ANL-E plans to operate the system for a period of up to 20 years. Afterward, the trees will be harvested, chipped, and used 

at the ANL-E campus as landscaping material. 

2.2 Operability of the Technology 

2.2.1 Site Screening 

2.2.1.1 Climate 

There are a number of variables that affect the operability of phytotechnology systems. Chief among these are 

precipitation and evaporation. Phytostabilization of groundwater flow is more likely to succeed in areas where annual 

evaporation exceeds annual precipitation (Hauser et al., 1999). This can be expressed as a ratio: 

xv 
Ratio = annual evaporation/annual precipitation. 

Annual evaporation is best represented by calculating potential evapotranspiration (PET). However, PET is a fairly 

involved calculation requiring a large variety of data inputs. Perhaps more appropriate for an initial screening is to use 

Class-A pan evaporation. Data are available at state water surveys (e.g., www.sws.uiuc.edu) and the National Weather 

Service (e.g., www.crh.noaa.gov). 

In areas were the ratio is greater than 1, the phytosystem should be able to lower the water table and control the migration 

of contaminants (Hauser et al., 1999). Where the ratio is below 1, engineering controls that may still allow successful 

phytostabilization. At ANL-E, where annual precipitation exceeds annual evaporation, the ground surface surrounding the 

poplar and willow trees was planted with vegetation to limit infiltration of precipitation to ground water. 

2.2.1.2 Hydraulic Setting 

In applications where hydraulic control is an important objective, phytostabilization success is more likely at sites where 

the water table is near the surface. Prior to 1999, tree-based systems were generally considered acceptable for 

groundwater depths to 20 ft (6 m). Below this depth severe reductions of water consumption were believed to occur 

(Hauser et al., 1999); however, the ANS TTTS® purportedly extends the treatment range to over 30 ft (9 m) bgs. (Refer 

back to section 1.2 for details on the ANS TTTS®.) 

2.2.1.3 Soil Properties 

During preliminary screening, data on surface soils, the vadose zone, and aquifer(s) of interest should be assembled and 

evaluated. Summary data are often available from the Natural Resources Conservation Service of the U. S. Department 

of Agriculture at either county or state offices. These data can help define the soil types likely to be found at the site if no 

significant construction or cutting and filling have occurred. 

Cemented, high-density layers of soil may be strong enough to prevent root penetration. Such layers should be identified 

during preliminary screening because, if they exist, they must be modified. (Hauser et al., 1999). The ANS TTTS® claims 

to overcome the limitations of high density soil by creating permeable zones to promote and direct root growth through the 

vertical extent of the affected media. (Refer back to section 1.2 for details on the ANS TTTS®.) 

2.2.1.4 Site Objectives and Plant Selection 

An important principle of phytotechnology is to match the plant species and subspecies to the site and planned 

applications. Each site will be different: Some will be in wetlands, some in rubble, others in well drained sandy soils. 

Different plants thrive in these various conditions. Choosing the appropriate plants for the growing conditions is critical 

because if plants cannot grow, they cannot affect contaminants. 

Different plants do well at remediating different types of contaminants. Some plants are better for treating heavy metals, 

others for volatile organics. Westphal and Isebrands (2001) lists some of the contaminants taken up by different species 

of poplars and willows: ammonium and nitrate nitrogen; barium, boron, cadmium, calcium, iron, magnesium, manganese, 

potassium, sodium, and zinc; BTEX, PAHs, TCE, and TNT; formaldehyde, herbicides, and pesticides; and cesium and 

strontium. It should be emphasized that not all poplar and willow species can metabolize these contaminants. Some 

varieties do, many do not. 

A final consideration in selecting the appropriate plant type is whether it is native to the ecosystem where the 

phytotechnology is taking place. This criterion is particularly important for sites near natural areas that need to be protected 

(Westphal and Isebrands, 2001). 

An important component of the ANS TTTS® is the selection of TreeMediation® vegetation (i.e., vegetation that is selected 

for its remedial capacity). ANS identified hybrid poplar and hybrid willow species known for their ability to treat TCE and 

other analytes of concern at the 317/319 Area. (Turn to section 4.2.5 for details on the selected poplar and willow species.) 

At the conclusion of the project, the poplar and willow trees will be harvested and the site will be re-planted with indigenous 

vegetation. 

xvi 
2.2.2 Engineering and Installation 

2.2.2.1 Plantation Design 

The design and performance assessment of phytotechnology systems requires a water balance. An important facet of 

the water balance is an understanding of the hydraulic framework surrounding the site. Data needs will include the 

following (EPA, 2001): 

• Groundwater flow pathways, direction, and velocity 

• Hydraulic gradient 

• Average depth to ground water 

• Aquifer thickness and recharge points 

• Seasonal and diurnal groundwater level fluctuations, 

• Connectivity of water bearing zones 

• Interrelation of the contaminated aquifer with other aquifers or surface water features 

• Principal mechanism of groundwater flow (intergranular or secondary porosity features) 

• Volume of groundwater flows through treatment area 

• Volume of ground water stored in aquifer underlying beneath treatment area 

• Fraction of precipitation percolating to ground water 

• Size and shape of the contaminant plume. 

Past remedial investigations, corrective measures studies, or the information centers mentioned earlier should provide 

much of the required data. A numerical groundwater model may be needed to estimate flow rates and volumes. Such 

a model can be calibrated to actual site conditions and used throughout the project to evaluate hydrogeologic data as it 

is collected. Another component of the water balance is determining the rates at which the candidate plants consume 

ground water as they mature and over the life of the project. This directly affects design parameters such as the number, 

placement, and spacing of plants required to achieve site goals (e.g., hydraulic containment, alter subsurface 

geochemistry). ANL-E has developed a website that allows viewing of animated results of groundwater flow modeling in 

support of the 317/319 Area phytosystem. The website address is http://web.ead.anl.gov/phyto/. 

A vegetative cover throughout a tree plantation helps to maximize total water use, control erosion, and keep shallow soil 

dry. Turn to section 4.2.5 for details on the vegetative cover deployed at the 317/319 Area. 

For a number of plant varieties, a growing information base of water use characteristics is available from sources such as 

(but not limited to) U.S. and international universities, U.S. Forest Service and state agencies, and phytotechnology 

consultants. 

The soil at treatment sites may have been significantly altered by past activities. Common adverse conditions include soil 

compaction and the addition of gravel or other oversized material. These conditions affect soil parameters such as bulk 

density, water holding capacity, porosity, and aeration. The soil at treatment sites should be investigated for its suitability 

as a growing medium. Hauser et al. (1999) lists important soil properties and associated test methods. One of the claimed 

advantages of the ANS TTTS® is that it can overcome the compacted soil in the 317 French Drain resulting from past soil 

mixing action. (Turn to section 4.2.4 for details about past treatment activities at the 317 French Drain.) 

2.2.2.2 Installation 

Ideally, plants should be installed early in the year to take advantage of the entire season. Early fall planting is acceptable 

since roots can begin to grow before the dormant season. 

Trees are normally transplanted as either cuttings or growing trees. Smaller trees are less expensive, but the root mass 

of larger ones will likely begin treatment quicker. Trees should be watched closely to guard against drying during transport 

and inspected for damage upon delivery. For larger applications, a protected staging area will aid systematic monitoring 

for signs of plant stress (e.g. foliar discoloration) during an extended installation period that could take several weeks or 

more to complete. Figure 2-1 shows ANL-E scientists inspecting plants prior to planting. 

xvii 
Figure 2-1. Inspecting plants prior to Planting 

It may be necessary to remove unsuitable native soil and 

foreign material in each tree installation point prior to 

placement. Soil borings (or “columns”) at each installation 

point is an new method pioneered by ANS. The drilling action 

removes heavy clay, hardpan, and other undesirable 

materials, which are then replaced by a combination of sand, 

peat, topsoil, and other materials to provide nutrients, wick 

water, and create a preferred growth path. 

Inadequate aeration at depth may retard root growth. At ANLE air inlet wells made of flexible perforated plastic pipe were 

installed to improve gas exchange within the rhizosphere. 

For phreatophytic trees it desirable for the roots to reach and 

utilize ground water as quickly as possible. However, a brief 

period of surface irrigation may be necessary during and after 

installation to minimize transplant stress and meet the 

moisture needs of the plants, particularly if weather conditions 

are unseasonably warm and dry. Willows planted in the 317 

French Drain were hand-watered periodically for several 

weeks after planting to alleviate stress from the hot, dry 

weather conditions. 

2.2.3 Operation and Maintenance 

2.2.3.1 Monitoring 

(Turn to section 4.2.6 for monitoring activities undertaken specifically for the ANL-E phytosystem.) 

Phreatophytic plants, with roots in or near the water table, can produce an obvious daily cycle of groundwater elevations 

beyond those exerted by variations in barometric pressure. The magnitude of these water level changes is more 

pronounced if the rate of groundwater recharge is less than the cumulative transpiration rate of the plantation. Continuous 

measurement of groundwater elevation within and outside planted areas will give a picture of the change in groundwater 

contours due to transpirative influence. 

If a site goal is the reduction of contaminants in the ground water or soil as a result of root growth and influence or natural 

attenuation, then ground water and soil quality should be monitored. Sampling and analysis should be performed as 

required to determine the change in contaminants. 

Climatological measurements should be obtained from either an onsite weather station (preferred) or one located nearby. 

Important parameters include precipitation, high/low daily temperature, humidity, wind speed, and solar radiation. These 

measurements permit the calculation of PET, which is useful in understanding changes in hydraulic conditions at the site 

and estimating transpiration rates for groundcover vegetation. 

One method to assess the physiological development of plants is based upon the amount of heat absorbed during the 

growing season. This is described by a quantity known as the cooling degree day (Ball and Jones, 1998). There are 

several methods for calculating cooling degree days (CDD), including a widely-used variant known as the growing degree 

day (GDD) originally developed for corn crops (Eckert, 1990). The Climate Prediction Center of the National Weather 

Service gives brief descriptions of the different types of degree days as well as current and archived data for a number of 

regions across the nation (www.cpc.ncep.noaa.gov). 

The quality of a growing season can be judged by comparing the current total site CDD against the average for the 

community. This is a simple and useful tool. A 1992 study of operational plantings on 50 to 100-acre agricultural-scale 

field plots in the north central United States indicated that among all the measured environmental characteristics, CDD had 

xviii 
the strongest correlation (r2

=0.91) to poplar productivity (Downing and Tuskan, 1995). CDD may also provide a method 

to normalize or predict the performance of phytotechnology systems in different geographic regions to a proposed site 

during initial screening. 

Evaluation of system performance is enhanced by measuring sapflow rate in individual trees after the plants have had a 

chance to recover from transplantation shock. Sap flow measurements are generally expensive and require a fair amount 

of expertise to collect and interpret. A number of different techniques and systems are available with varying degrees of 

accuracy (Smith and Allen, 1996). Indirect methods of determining sapflow rates are based upon correlations between 

sap flow and PET, basal diameter, or total leaf area. These methods are less accurate, but far less costly. 

The overall health of the plants should be monitored on a regular basis. On-site inspections can determine whether 

disease, insects, wildlife, or lack of adequate plant nutrients is affecting rate of growth, water consumption, or plant health. 

Inspections should periodically include a sampling of basic measurements such as tree height, (basal) trunk diameter, and 

(after several growing seasons) canopy width. 

2.2.3.2 Maintenance 

The loss and replacement of plants during the treatment period should be expected. Losses are due to a number of 

reasons including transplant shock, nutrient deficiency, disease, wind or hail damage, and insect and animal predators, 

to name just a few. First year losses for willow and poplar trees have been reported between 5% and more than 50%. First 

year losses at ANL-E were less than 5%. 

A vibrant stand of young trees is an inviting sight to animal and insect predators. In most cases were a problem develops, 

a fence will be needed to protect the plants from being damaged by animals. (ANL-E constructed a gated 8-ft tall security 

encircling entire study area). GDD can be used as a tool for insect pest management. The University of California at 

Davis maintains a phenology database that relates insect life cycle to the number of degree days that have accrued. Many 

insects require a certain amount of heat in order to evolve from one stage of development to another. Such infor-mation 

can be useful in planning pest management options. The website, www.ipm.ucdavis.edu/ 

PHENOLOGY/models.html, gives details about this database. 

2.2.4 Site Closure 

If the site does not require removal of the trees, they can be left in place. It is unlikely that the shoots (above ground tree 

material) will contain a significant amount of accumulated organic contaminants, particularly at the end of the remediation 

period when the concentration of contaminants in the water is low enough to meet cleanup goals. As a result, there should 

be no obstacles to the general disposal or reuse of tree parts or other biomass if they must be removed. However, if 

significant metals (determined on a case-by-case basis) were present in the groundwater plume, sampling of the roots 

may be required to determine disposal options (Hauser et al., 1999). At the conclusion of the ANL-E phytosystem 

deployment, ANL-E plans to harvest the trees and use wood on-campus. 

2.3 Applicable Wastes 

Generally, tree-based phytotechnology is best applied to sites with relatively shallow soil and groundwater contamination 

containing non-toxic levels of pollutants. Chappell (1997) reported separate case studies involving hybrid poplars treating 

groundwater containing more than 220 mg l-1 CAHs. The contaminants, whether organic or inorganic, should possess 

certain physical and chemical properties that make them amenable to phytotransformation, rhizosphere bioremediation, 

and/or phytoextraction. Burken and Schnoor (1998) reported that chemicals with moderate hydrophobicity (i.e., log Kow 

= 1 to 3.5) make good candidates for extraction. Such chemicals include benzene, toluene, ethylbenzene and xylenes 

(BTEX), and short-chain (chlorinated and ono-chlorinated) aliphatic compounds. 

2.4 Availability and Transportability of the Equipment 

Unlike conventional technologies, phytotechnology systems do not involve mechanical equipment beyond that necessary 

for installation. 

xix 
Figure 2-2. Tree Installation at ANL-E 

Plants can usually be obtained from a nursery or tree 

farm and trucked to the site. Equipment required to 

install the system is entirely site specific, and to a 

large extent, dependent upon the soil conditions, 

target installation depth, and the size of the plots. For 

example, a pile driving crane with a 46-cm (18-in) 

auger was used to a depth up to 9 m (30 ft) bgs to 

install the poplars and willows at the ANL-E site. Site 

prep tasks such as clearing and grading can be outsourced. 

Other equipment that might be necessary during plant 

installation includes a backhoe, front-end loader and 

skid mounted loader for moving fertilizer, top soil and 

fill around the site, a mixing unit and a screen for 

blending the planting soil, a trencher for burying data 

cables, and discing and plowing equipment for 

loosening the ground surface and incorporating 

fertilizer and soil conditioners. This equipment can usually be rented locally. Figure 2-2 shows a portion of the tree 

installation process at ANL-E. 

Typical monitoring equipment for sites where hydraulic control is a priority includes a network of monitoring wells. These 

wells can be equipped with electronic pressure transducers connected to data loggers for continuous water level 

monitoring. Weather stations are often installed at large plantations whenever other reliable data sources are not 

available. 

2.5 Materials Handling Requirements 

Materials handling is required mainly during three phases of the project: site preparation, plant installation, and site 

closure. Refuse from site preparation typically includes plant biomass and waste debris from clearing and surface soil 

and other material from grading. These items are usually uncontaminated and can be disposed of at a general landfill. 

Treatment area soils may require incorporation of fertilizer and soil conditioners at the time of planting. Fertilizer could 

include any variety of commercially-available products depending on the desired nitrogen/phosphorus/potassium (NPK) 

ratios. Soil conditioners have traditionally included aged manure, sewage sludge, compost, straw and mulch. A mix 

mill/grinder and spreader can facilitate handling of these products. Screening equipment (i.e. subsurface combs, portable 

vibrating screens) may also be necessary to remove debris and cobbles from the soil. Turn to 4.2.5 for details about 

fertilization and soil conditioning at the 317/319 Area. 

Installation byproducts, such as contaminated soil, may require specialized handling, storage and disposal. At ANL-E, 

the majority of drill cuttings were not considered contaminated and were spread across the ground surface at the site. 

Any drill cuttings that are considered contaminated are typically containerized (55-gallon drums, e.g.) and disposed of at 

a permitted facility. During installation, soil should be kept damp when being worked to limit dust production. 

In a large-scale application, as many as 1,000 trees per acre may be planted initially to assure a significant amount of 

evapotranspiration in the first few years. In order to partially offset capital costs, the trees can be harvested on a periodic 

rotation and sold as fuel-wood or for pulp and paper production. The trees will grow back from the cut stump. ANL-E 

plans to operate their system for a period of up to 20 years. Afterward the trees will be harvested, chipped, and used at 

the ANL-E campus as landscaping material. 

2.6 Site Support Requirements 

Phytotechnology systems in general have minimal site support requirements and require few utilities to operate. Water 

is generally needed for irrigation and possibly decontamination purposes. A drip irrigation system may be installed and 

operated periodically over the first few growing seasons when the young trees are most susceptible to water stress. It 

xx 
may be operated at times afterwards to make up for rainfall deficits that occur during times of drought. Irrigation water 

would not necessarily have to be potable water. Depending upon local regulations, water from the contaminated aquifer 

might be used at no cost, with the additional benefit of enhancing groundwater treatment during the first few growing 

seasons when little remediation is expected. 

The electricity needed to operate well pumps can be provided by small generators. Monitoring equipment (e.g., soil 

moisture probes, pressure transducers, data loggers, weather station components) can be powered by batteries or solar 

panels, as was the case at ANL-E. 

Depending upon site location, security measures might be required to protect the public from accidental exposures and 

prevent accidental and intentional damage to the trees and monitoring equipment. A fence would also serve the purpose 

of discouraging local wildlife from using the trees as a food source. 

2.7 Range of Suitable Site Characteristics 

The suitability of the soil, groundwater, and climate for growing plants is assessed during initial site screening (refer back 

to section 2.2.1) and then refined for specific candidate plants and site objectives during the design phase (refer back 

to section 2.2.2). 

A tree-based phytotechnology system is land intensive, requiring plenty of clear space, or at least a sufficient amount to 

hold the number of trees necessary to meet site goals. The site surface should be stable and capable of handling traffic 

from trucks, trailers, and construction-type heavy equipment. 

2.8 Limitations of the Technology 

Although current research continues to explore the boundaries of phytotechnology applications, there are some limiting 

factors that need to be considered. 

Contaminant-to-root contact, a function of root mass and depth, is a limiting factor for direct uptake of contaminants. To 

overcome the depth barrier researchers (e.g., ANS) have developed and employed specialized (often proprietary) 

techniques that train the tree roots to penetrate to greater depths. 

Contamination that is too tightly bound to the organic portions of a soil and root surfaces may also pose limitations. This 

is especially true with hydrophobic compounds (logKow > 3.5) that cannot be easily translocated within the tree or are 

simply unavailable to microorganisms in the rhizosphere. Contaminants that are water soluble (logKow <1.0) simply pass 

through the roots unimpeded. 

High concentrations of organics may inhibit tree growth (Dietz and Schnoor, 2001). Sites that possess toxic levels of 

organic contamination are best handled by other techniques. A tree-based phytotechnology system can then serve as 

a secondary step after hot spots have been treated. 

A potential impediment from a regulatory standpoint is the transfer of contaminants or metabolites to the atmosphere. 

Transpiration of TCE to the atmosphere has been measured (Newman et al., 1997); however, there is little indication of 

releases of more toxic daughter products (i.e., vinyl chloride). 

2.9 Technology Performance versus ARARS 

ANL-E is a government-owned, contractor-operated research and development facility that is subject to environmental 

statutes and regulations administered by the EPA, the Illinois Environmental Protection Agency (IEPA), U.S. Army Corps 

of Engineers (COE), and the State Fire Marshal, as well as to numerous DOE Orders and Executive Orders. A detailed 

listing of regulations applicable facility-wide is contained in DOE Order 5400.1, which establishes DOE’s policy concerning 

environmental compliance. Some of these regulations can be described as applicable or relevant and appropriate (ARAR) 

to the 317/319 Area phytotechnology site. Others may not, but are common to other cleanup sites and are worth 

examining in the present context. The list includes the following: 

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• Resource Conservation and Recovery Act 

• Comprehensive Environmental Response, Compensation, and Liability Act 

• Clean Water Act 

• Clean Air Act 

• Toxic Substances Control Act 

• Worker Safety and Training 

• Other Statutes 

Much of the information presented was derived from the ANL-E document, Site Environmental Report for Calendar Year 

2001 (Golchert and Kolzow, 2002). ARARs are summarized in Table 2-1 located at the rear of this section. 

The regulatory setting of each contaminated site is unique. Readers evaluating ARARs for a particular remediation project 

are strongly urged to seek experienced guidance. 

2.9.1 Resource Conservation and Recovery Act 

The Resource Conservation and Recovery Act (RCRA) and its implementing regulations are intended to ensure that 

facilities that treat, store, or dispose of hazardous waste do so in a way that protects human health and the environment. 

The Hazardous and Solid Waste Amendments of 1984 created a set of restrictions on land disposal of hazardous waste. 

The HSWA also require that releases of hazardous waste or hazardous constituents from any Solid Waste Management 

Unit (SWMU) at a RCRA-permitted (RCRA Part B Permit) facility be remediated, regardless of when the waste was placed 

in the unit or whether the unit originally was intended as a waste disposal unit. 

The IEPA has been authorized to administer most aspects of the RCRA program in Illinois. The IEPA issued a RCRA Part 

B Permit to ANL-E and DOE in September 1997 and it became effective in November 1997. The Part B Permit identifies 

49 SWMUs and 5 areas of concerns, which includes portions of the 317/319 Area. The remediation program for the 

317/319 Area as well as the other units is under the authority of the Part B Permit and is being conducted in accordance 

with IEPA-approved corrective action work plans. 

2.9.2 Comprehensive Environmental Response, Compensation, and Liability Act 

The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), commonly known as 

Superfund, addresses the cleanup of hazardous waste disposal sites and the response to hazardous substance spills. 

Under CERCLA, the EPA collects data regarding sites subject to CERCLA action through generation of a Preliminary 

Assessment, followed up by a Site Screening Investigation (SSI). Sites then are ranked on the basis of the data collected 

according to their potential for affecting human health or causing environmental damage. The sites with the highest 

rankings are placed on the National Priority List (NPL) and are subject to mandatory cleanup actions. No ANL-E sites are 

included in the NPL. 

Remedial actions to clean up any release of hazardous materials from inactive waste sites follows one of two main routes. 

The first is through the CERCLA program and is generally used for abandoned sites. The second route is the RCRA 

corrective action process, which is used frequently for waste sites on active facilities. SWMUs are the units subject to 

RCRA corrective action. Of the sites described in the ANL-E SSI reports, most are included as SWMUs in the RCRA Part 

B Permit. The ANL-E phytotechnology action is part of an effort to cleanup two SWMUs located in the 317/319 Area. 

2.9.3 Clean Water Act 

The Clean Water Act (CWA) was established in 1977 as a major amendment to the Federal Water Pollution Control Act 

of 1972 and was modified substantially by the Water Quality Act of 1987. Section 101 of the CWA provides for the 

restoration and maintenance of water quality in all waters throughout the country, with the ultimate goal of “fishable and 

swimmable” water quality. The act established the National Pollutant Discharge Elimination System (NPDES), which is 

the regulatory permitting mechanism designed to achieve this goal. The authority to implement the NPDES program has 

been delegated to those states, including Illinois, that have developed a program substantially the same and at least as 

stringent as the federal NPDES program. 

xxii 
The 1987 amendments to the CWA significantly changed the thrust of regulatory activities. Greater emphasis is placed 

on monitoring and control of toxic constituents in wastewater, the permitting of outfalls composed entirely of storm water, 

and the imposition of regulations governing sewage sludge disposal. These changes in the NPDES program resulted in 

much stricter discharge limits and greatly expanded the number of chemical constituents monitored in the effluent. 

In November 1990, the EPA promulgated regulations governing the permitting and discharge of storm water from industrial 

sites. The ANL-E site contains a large number of small-scale operations that are considered industrial activities under 

these regulations and, thus, are subject to these requirements. There are two permitted storm water outfalls in the 

317/319 Area. Parameters routinely inspected include flow measurements; analyses for certain specified pollutants 

including VOCs considered target analytes for this project; and dates, durations, and precipitation volumes for monitored 

storm events. 

2.9.4 Clean Air Act 

The Clean Air Act (CAA) is a federal statute that sets emission limits for air pollutants and determines emission limits and 

operating criteria for certain hazardous air pollutants. The program for compliance with the requirements is implemented 

by individual states through a State Implementation Plan that describes how that state will ensure compliance with the air 

quality standards for stationary sources. 

A number of major changes to the CAA were made with the passage of the Clean Air Act Amendments of 1990. Under 

Title V of the Clean Air Act Amendments of 1990, ANL-E was required to submit a Clean Air Act Permit Program 

application to the IEPA for a sitewide, federally enforceable operating permit to cover emissions of all regulated air 

pollutants at the facility. All facilities designated as major emission sources for regulated air pollutants are subject to this 

requirement. ANL-E meets the definition of a major source. Facilities subject to Title V must characterize emissions of 

all regulated air pollutants, including oxides of nitrogen, sulfur dioxide, carbon monoxide, particulate matter, volatile organic 

compounds (VOCs), hazardous air pollutants (HAPs, a list of 188 chemicals, including radionuclides), and ozone-depleting 

substances. The ANL-E site contains a large number of air emission point sources; however, projected emissions from 

the 317/319 Area phytotechnology are considered minimal, so the site is not counted as an emission point source. 

The National Emission Standards for Hazardous Air Pollutants (NESHAP) constitute a body of federal regulations that set 

forth emission limits and other requirements, such as monitoring, record keeping, and operational and reporting 

requirements, for activities generating emissions of certain HAPs. The only standards affecting ANL-E operations are those 

for asbestos and radionuclides. By the end of 2001, the IEPA had issued a total of 21 air pollution control permits to ANLE for NESHAP sources. The 317/319 Area is not considered a NESHAP source and therefore does not require an air 

pollution control permit. 

2.9.5 Toxic Substances Control Act 

The Toxic Substances Control Act (TSCA) was enacted to require chemical manufacturers and processors to develop 

adequate data on the health and environmental effects of their chemical substances. The EPA has promulgated 

regulations to implement the provisions of TSCA. These regulations provide specific authorizations and prohibitions on 

the manufacturing, processing, and distribution in commerce of designated chemicals. The principal impact of these 

regulations at the ANL-E site concerns the handling of asbestos and polychlorinated biphenyls (PCBs). 

PCB items in use or in storage for reuse are tracked by the ANL-E PCB Item Inventory Program. All PCB items identified 

by the PCB Item Inventory Program have been labeled appropriately with a unique number for inventory and tracking 

purposes. None of the PCB items are located currently within the 317/319 Area. 

2.9.6 Worker Safety and Training 

All SAIC employees and subcontractors who performed work in the 317/319 Area had to complete the initial 40-hr 

Hazardous Waste Operations and Emergency Response (HAZWOPER) training course per 29 CFR 1910.120(e)(3)(i) and 

the annual 8-hr HAZWOPER refresher training per 29 CFR 1910.120(e)(8) within the past 12 months. In addition, SAIC 

xxiii 
field managers directly responsible for overseeing field work had to complete the 8-hr Hazardous Waste Site Worker 

Supervisor training course per 29 CFR 1910.120(e)(4). 

For the final sampling event SAIC added a Competent Person for Excavation and Trenching to the soil sampling field crew. 

Some months before, the ANL-E Construction Safety Officer (CSO) in charge of the 317/319 Area determined that using 

a Geoprobe® is considered "excavation." As such, he directed that the "excavation" operation be supervised by a 

"competent person" as defined by 29 CFR 1926.650. 

SAIC included a sample shipping manager trained per 49 CFR 172.704, Hazardous Materials Packing and Handling. The 

methanol extracts developed as a component of the soil sampling program were considered a hazardous material. 

All SAIC personnel and subcontractors were required to complete a computer-aided Radiological Worker Training I course 

(4 hours) per 10 CFR 839.902 and attend a contractor safety orientation (1-1/2 hours) prior to entering the field work area. 

The course and orientation were provided on-site by ANL-E. 

In addition to the comprehensive health and safety plan (HASP) prepared for USEPA, SAIC prepared and submitted to 

ANL-E a series of Job Safety Analysis (JSA) documents. The JSA is the ANL-E equivalent of a HASP, except that it 

focuses solely on the tasks to be performed during a specific work event (field or laboratory). The JSA was updated and 

re-submitted prior to each work event. 

SAIC obtained ANL-E dig permits for all field activities that involved penetrating the ground surface within the 317/319 

Area. 

All powered equipment and tools were inspected by the CSO prior to entry and use in the 317/319 Area. Any and all 

defects were replaced or corrected and re-inspected. 

2.9.7 Other Statutes 

Rock and Sayre (1998) have identified other statutes and rules potentially applicable to phytotechnology projects. Plants 

used for phytotechnology are potentially regulable under several U.S. statutes. The United States Department of 

Agriculture (USDA) administers several statutes that could be used to regulate such plants; e.g., The Federal Plant Pest 

Act (7 U.S.C. 150 et seq.), the Plant Quarantine Act (7 U.S.C. 151 et seq.), and the Federal Noxious Weed Act (7 U.S.C. 

2801 et seq.). Pertinent regulations are found at 7 CFR parts 319, 321, 330, 340, and 360, respectively. Under USDA 

authorities one type of plant (transgenic or naturally-occurring) which would potentially be subject to review would be a 

plant considered to be a plant pest. For additional guidance on USDA regulations pertaining to plants, consult the USDA 

web site http://www.aphis.usda.gov/bbep/bp/. 

The U.S. EPA does not currently regulate plants intended for commercial bioremediation, although EPA believes the TSCA 

gives EPA authority to do so, if such action is necessary to prevent unreasonable risk to human health or the environment. 

TSCA gives EPA authority to regulate " chemical substances". TSCA defines chemical substances broadly to mean all 

organic and inorganic chemicals and mixtures of chemicals, including products, byproducts and residues. Living 

organisms, such as plants, are mixtures of chemical substances and thus are subject to TSCA. Although TSCA could 

potentially be applied to plants used in bioremediation, EPA has not yet made a determination of whether such action is 

necessary to protect the environment and human health. EPA to date has only issued regulations for microorganisms 

under section 5 of TSCA (EPA, 1997). Further information on TSCA and biotechnology products can be found at 

http://www.epa.gov/opptintr/biotech/. 

xxiv 
Table 2-1. Federal and State Requirements for a Tree-Based Phytotechnology System 

Process Activity ARAR Description Comment 

Cleanup Process CERCLA: 40 CFR 

300 

RCRA: 40 CFR 261 

(or State Equivalent) 

Waste from drilling RCRA: 40 CFR 261 

and excavation (or State Equivalent) 

activities related to 

system installation 

Wastewater or storm CWA: 40 CFR 122 

water discharges (or State Equivalent) 

from site 

Air emissions from CAA: 40 CFR 70 

large tree stand (State operating 

permit); 40 CFR 61 

and 63 NESHAP 

All field activities OSHA: 29 CFR 

1910.120 

DOE: 10 CFR 835 

CERCLA generally applicable to 

abandoned sites, RCRA to active 

businesses or organizations. 

Determine waste components; may be 

hazardous if listed or characteristic waste is 

present. 

Discharges of wastewater and storm water 

from industrial facilities, including waste 

treatment sites. 

Stationary sources above threshold 

quantity of regulated pollutant require CAA 

permit. Under NESHAP, remediation at 

source owner site may constitute 

construction or modification. 

All field work conducted at CERCLA or 

RCRA sites requires OSHA worker training 

and monitoring; radiological sites may 

require additional training prescribed by 

DOE. 

ANL-E 317/319 Area cleanup 

under RCRA Part B Permit 

Small amount of hazardous 

drill cuttings generated during 

installation at 317 French Drain 

317/319 Area has two storm 

water outfalls to nearby creek. 

Effluent permitted and 

monitored on routine basis. 

ANL-E considered a major 

source; however, regulations 

not applicable to 317/319 Area 

activities. 

Applicable to field work at 

317/319 Area. 

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xxvi
SECTION 3

ECONOMIC ANALYSIS

3.1 Introduction 

The purpose of this economic analysis is to present the actual and planned (future) costs of the phytotechnology system 

deployed at the ANL-E 317/319 area. This evaluation is of a full-scale operation that is being implemented as part of an 

ongoing RCRA Corrective Action. 

The primary source of the cost information is Mr. Jim Wozniak, the ANL-E project manager (630-252-6306). In describing 

project expenditures, Mr. Wozniak identified five major cost categories organized by fiscal year (FY). The categories are 

as follows:

 (1) Inspection/Assessment and Develop

Monitoring Plan (FY99)

 (2) Engineering and Deployment (FY99)

 (3) Non-O&M costs (FY00-FY02)

 (4) O&M costs (FY99-FY02)

 (5) Recurring O&M costs (FY03-FY19) 

Amounts reported for the period FY99 through FY02 represent actual expenses. Costs attributed to the period FY03 

through the end of the treatment (FY19) are estimates. 

This section concludes with a cost comparison between the ANL-E phytosystem and the DOE baseline technology that 

features an asphalt cap and extraction wells. 

3.2 Conclusions 

The following conclusions have been drawn based upon the information provided by ANL-E: 

• The cost for designing, installing, and maintaining the system for the first four years (1999-2002) is $2,382,632. 

This is the sum of Non-Recurring ($1,480,000), Non-O&M ($589,432), and O&M ($313,200) costs. 

• The total amount of the system over the 20 year treatment period is $4,592,632 ($38/ft2

). This includes estimated 

O&M expenditures of $2,210,000 for the period FY03 to FY19. 

• Approximately 32% ($1,480,000) of the total cost was incurred designing and installing the system. Over the 

duration of the project O&M is the dominant expense, estimated at 55% ($2,532,000) of total cost. 

Table 3-1 presents the categorical breakdown of actual and future costs. 

xxvii 
Table 3-1. Cost Estimates for the ANL-E Tree-Based Phytotechnology System. 

ANL-E CATEGORIES ITEMIZED COSTS --------TOTALS-------­ % of TOTAL COST 

FY99 NON-RECURRING COSTS 

1. Inspection/Assessment & Develop Monitoring Plan 1 $222,000 

2. Engineering & Deployment $1,258,000

 2a - Engineering 2 $262,400

 2b - Deployment $995,600 

-- Drilling 3 $170,800 

-- Planting 4 $184,800 

-- Oversight 5 $357,600 

-- Other Efforts & Subs 6 $282,400 

Total ANL-E FY99 Non-Recurring Costs ÷ $1,480,000 32.2% 

NON-O&M COSTS (FY00-FY02) 

3. Non-O&M Costs

 3a - Applied Natural Sciences $72,232

 3b - ANL-E Energy Systems $517,200 

Subtotal of Non-O&M Costs for FY00-FY02÷ $589,432 12.8% 

O&M COSTS 

4. FY99-FY02 O&M Costs $313,200 

5. Recurring O&M Costs ($130,000 x 17 years) $2,210,000 

Subtotal of all O&M Costs for FY99-FY19÷ $2,523,200 

Projected Total ANL-E Phytotechnology Costs for FY99-FY19÷ $4,592,632 

55% 

100% 1

 Tasks associated with Inspection/Assessment & Develop Monitoring Plan include inspecting tree livestock at site (e.g., assessing root mass, taking

 and recording stem caliper measurements). Monitoring plan included the monitoring tasks for the first growing season (1999).

 Expenditures, which are estimated at about 95% labor, cover approximately three full-time ANL-E personnel during 1999. 2

 Of the $262,400, approximately 90% are labor. Tasks include collecting soil samples with a Geoprobe®, analyzing those soil samples for agronomic

 analyses by ANS. Tasks also included producing engineering specifications/drawings and installation details for IEPA

 review. Costs include all support from ANL-E project management for 1999. 3

 Drilling includes the drilling of tree holes in the French Drain area as well as in the hydraulic control area. 4

 Planting includes the physical placement of trees into the holes along with previously purchased soil amendments. 5

 Oversight includes the cost of furnishing the trees and the ANS scientific effort overseeing the entire planting operation. 6

 Other Efforts and Subs include a variety of miscellaneous costs. Major costs include the installation of about 60 monitoring wells, the purchase of

 topsoil, sand, and manure; and the deforestation (including stump removal) of the eastern portion of the 319 area.

xxviii 
3.3 Issues and Assumptions 

3.3.1 Site Characteristics 

Costs presented reflect the complexity of the type and method of treatment required at the 317/319 Area. For example, 

instead of using inexpensive whips or cuttings, the deep soil and groundwater contamination called for the installation of 

specially developed trees with large root masses capable of reducing the dormancy period before actual treatment begins. 

Instead of using picks and hand shovels, the ANS TTTS® installation processes demanded a heavy-duty auger and earthmoving equipment to emplace the trees at depth and clear and spread substantial amounts of drill cuttings. It is expected 

that cost differences will result at sites with less challenging treatment needs. 

Although not evaluated in this cost analysis, it is anticipated that larger sites employing a similar treatment approach will 

experience greater economies of scale from certain fixed cost elements. In particular, those items identified in Table 3-1 

as category 1, 2a, and 3 represent approximately 23% of the total figure and are less sensitive to total treatment area than 

other cost elements. Application of these outlays against a larger site would decrease their unit cost. 

Table 3-2 provides the dimensions of the 317/319 planted surface. 

Table 3-2. Total Tree Planted Surface Area 

ANL-E AREA OF HYDRAULIC CONTROL/TREATMENT ESTIMATED PLANTED SURFACE AREA 

- 317 Area French Drain 270' x 75' = 20,250 ft2 

- Area South (Downgradient) of 317 Area French Drain 370' x 120' = 44,400 ft2 

- Area South (Downgradient) of 319 Area Landfill 400' x 130' = 52,000 ft2 

Total Area 116,650 ft2 

3.3.2 Design and Performance Factors 

The number of growing seasons required for sufficient tree growth is a considerable variable. Climate has a direct impact 

on the growth of trees and, therefore, affects the total number years needed to achieve cleanup goals. 

The need for specialized monitoring equipment utilized by EPA during this SITE demonstration is highly dependent on 

minimum data needs and budget. For this project, specialized monitoring equipment included sap flow sensors, electronic 

soil moisture probes, groundwater well pressure transducers, minirhizotrons, multi-parameter water quality meters used 

during groundwater sample collection, an onsite weather station, and solar-recharged dataloggers. The minimum data 

needs of other projects may not warrant the expense of some or all of these items; therefore, their costs have been 

excluded from this analysis. 

3.3.3 Financial Assumptions 

All costs are in U.S. dollars. For FY99 to FY02 amounts are actual expenses based upon the year in which they were 

incurred. Projected O&M costs (FY03-FY19) are in 2003 dollars and provided without accounting for interest rates, 

inflation, or the time value of money. 

3.4 Basis for Economic Analysis 

The five categories used in this cost analysis were provided by ANL-E, and each is discussed in this section. 

xxix 
3.4.1 Inspection/Assessment & Develop Monitoring Plan 

The category referred to by ANL-E as Inspection/Assessment & Develop Monitoring Plan can be considered as a collection 

of site preparation-type costs. Inspection/Assessment consists mostly of the field activities conducted prior to actual tree 

planting. Tasks are reported to involve inspecting tree livestock at the site (e.g., assessing root mass, and taking and 

recording stem caliper measurements). 

Monitoring Plan is reported to include monitoring tasks for the first growing season. The majority (an estimated 95%) of 

the $222,000 expenditure covered approximately three full-time ANL-E personnel during 1999. These personnel were 

higher level professionals (e.g., engineers and scientists). 

3.4.2 Engineering and Deployment 

3.4.2.1 Engineering 

Engineering includes review and assessment of data for the purpose of determining the nature and extent of the required 

deployment. Some of the data were developed through Geoprobe® soil sampling and analysis for agronomic parameters. 

Agronomic analyses determine the condition and general ability of the soils to promote healthy tree growth. This category 

also includes production of engineering specifications, drawings, and installation details for review by IEPA. This category 

includes all ANL-E management support for 1999. Engineering cost was reported as $262,400, of which an estimated 

90% is labor. 

3.5.2.1 Deployment 

Deployment consists of a number of pre- and post-planting activities that are described by four subcategories: Drilling, 

Planting, Oversight, Other Efforts and Subcontractors. 

Drilling. This category includes the specialized tree installation services that produced the borings needed to place the 

trees at the proper depth. While all trees were deep planted, only those in the hydraulic control areas utilized the patented 

TreeWell® method. Total Drilling cost was reported as $170,800, which is a mix of labor, equipment rentals, and field 

supplies. 

Planting. This category includes the physical placement of trees. Over 800 hybrid poplar and willow trees were planted 

during the summer of 1999 in and downgradient of the 317/319 Area at predetermined and varying depths. The trees were 

planted along with amendments (topsoil, sand, and manure). Planting also involved installing a vegetative cover among 

the trees to control soil erosion and minimize water infiltration. Planting costs were reported as $184,800, of which 100% 

is described as labor. 

Oversight. This category covers the subcontracted ANS effort overseeing the entire planting operation. Oversight cost 

was reported as $357,600. This category also includes expenses for the 809-tree inventory ($107,266), which is a 

cumulative total comprised of the purchase of sapling poplars ($189 each) and willows ($61 each), two-years’ nursery 

development, delivery of the tree livestock to the 317/319 Area by truck, and pre-planting care. 

The use of an irrigation system was intentionally avoided in order to encourage root growth toward the target aquifer. The 

willows in the 317 Area French Drain were hand watered for several weeks after planting to lessen transplant shock and 

relieve the stress caused by a period of severe heat and dry conditions. The labor for manual watering is included in this 

category. 

Other Efforts and Subs. This category represents a catch-all for tasks not covered under the previous categories. 

Significant activities include the installation of groundwater monitoring wells (about 60); purchase of amendments such 

as topsoil, sand, and manure; and deforestation and stump removal (via subcontractor) within the eastern portion of 319 

Area. The total cost of Other Efforts and Subs was reported as $282,400, which is a mix of labor, equipment purchases 

(wells) and rentals, and field supplies. 

xxx 
3.4.3 Non-O&M Cost (FY00-FY02) 

This category consists of efforts by ANL-E scientific investigators and ANS. ANL-E tasks focus on data collection and 

review, performance evaluations, and periodic internal progress reports. ANS tasks include assessments of tree stand 

health and replacement of dead trees. Non-O&M costs for ANL-E were reported as $517,200, which was 100% labor. 

Non-O&M costs for ANS were reported as $72,232 and represent a mix of labor, equipment purchases (trees) and rentals, 

and field supplies. 

3.4.4 O&M Cost (FY99-FY02) 

This category consists of establishing O&M routines during the early stages of the project and one-time maintenance 

events (e.g., perimeter fence repair). O&M routines were established for grass mowing; tree stand walk-throughs and, 

periodically, more intensive surveys to collect and evaluate physiological measurements (e.g., basal diameter, tree height, 

canopy width); and quarterly groundwater verification sampling and reporting for IEPA. 

Approximately 20 of the 60 wells at the 317/319 area are monitored on a quarterly basis. ANL-E utilizes dedicated bailers 

to collect ground water samples from each well. Annual analytical laboratory costs are reported as approximately $26,000, 

which consists of 156 VOC samples at $120 per sample ($18,720) and 156 tritium samples at $46 per sample ($7,176). 

The total outlay for O&M Costs (FY99-FY02) is reported as $313,200, which is primarily a mix of labor and subcontracted 

services. 

3.4.5 Recurring O&M Cost (FY03-FY19) 

This category represents a continuation of the O&M routines established during FY99-FY02. The total cost of Recurring 

O&M Costs is reported as $2,210,000, which is based on estimated expenditures of $130,000 per annum. 

3.5 Comparison between ANL-E Phytosystem and DOE Baseline Technology 

As described in section 1.1.1, the functional requirements for the final remedial actions in the 317/319 Area are to (1) 

prevent the release of soil contamination to ground water, (2) minimize the offsite migration of ground water containing 

VOCs and tritium from source areas, and (3) minimize the release of contaminants to stormwater runoff. Two approaches 

were considered: the DOE baseline, featuring traditional mechanical systems, and a phytotechnology alternative. These 

two approaches are discussed below. 

3.5.1 Baseline Approach 

Under the baseline approach, the specific actions taken would include (1) containing residual VOC contamination in the 

area under an asphalt cap and (2) preventing the release of contaminated ground water by installing a hydraulic 

containment system. The system would be installed within and downgradient of the 317 Area French Drain and include 

groundwater extraction wells to intercept the lateral migration of the plume. For the 319 Area Landfill, the objectives would 

be achieved by continuing to contain the waste material in the landfill under the existing impermeable cap, and operating 

the existing leachate and groundwater collection system at the 319 Area Landfill. 

3.5.2 Phytotechnology Approach 

Under the phytotechnology approach, a hybrid-tree-based system and a vegetative cap at the 317/319 Area was deployed 

to (1) hydraulically contain the VOC and tritium plumes south of the 317 Area French Drain and 319 Area Landfill, (2) 

continue the remediation of residual VOCs within the 317 Area French Drain, and (3) minimize water infiltration into the 

317 Area French Drain soils and stabilize the surface to prevent erosion, runoff, and downstream sedimentation. (Turn 

to section 4.2.5 for further details about the deployed phytotechnology system.) 

xxxi 
3.5.3 Technical Comparison 

According to ANL-E (1999), the phytotechnology approach has several distinct technical advantages over the baseline 

approach. These advantages are discussed below. 

3.5.3.1 More Effective Reduction in Plume Size 

An engineered plantation across the southern portion of the 317/319 Area establishes an extensive root network in the 

desired areas. ANL-E believes this approach should be much more effective than employing the anticipated 36 

groundwater extraction wells under the baseline approach. Previous (ANL-E) experience has shown that the zone of 

influence of groundwater extraction wells in the glacial till soil is very limited. (Turn to section 4.2.2 for details on the site’s 

hydrogeologic setting.) In contrast, the roots of the hybrid poplar and willow trees penetrate throughout the soil column 

seeking out water in the saturated porous zones and shifting location in response to seasonal changes in groundwater 

location and flow. 

3.5.3.2 Source Removal 

As described in sections 1.1.6.1 and 2.2.1.4, hybrid poplar and willows have the ability to destroy the type of VOCs found 

at the 317/319 Area through rhizo- and phytodegradative processes. The baseline approach does not encourage the 

destruction of contaminants. As a result, the contaminated soil would remain as a potential source of contamination for 

decades, requiring careful maintenance of the cap and groundwater collection system. 

3.5.3.3 Waste Prevention 

ANL-E projects that the phytotechnology system significantly reduces the generation of secondary waste requiring 

additional treatment. The largest secondary waste stream under both options is ground water. The minimum design 

estimate of groundwater removal is approximately 1,000 gallons per day (3,900 liters per day), and increases depending 

upon seasonal fluctuations. Under the baseline approach the ground water would be pumped from the various wells and 

discharged to the ANL-E wastewater treatment facility. However, with the phytotechnology system in full effect, the ground 

water should be transpired by the trees and released directly to the atmosphere as water vapor. 

3.5.4 Cost Comparison 

According to ANL-E (1999), the phytotechnology approach has the potential to result in large cost savings over the 

baseline approach. Under the phytotechnology approach, system design and installation (FY99), other sunk costs (FY00­

FY02), and non-recurring O&M (FY00-FY02), cost categories that represent items 1-4 in table 3-1, amount to $2,382,632. 

The equivalent cost for the baseline approach is approximately $400K more at $2,789,872. ANL-E estimated recurring 

O&M costs of $233,636 per annum, which is slightly more than $100K greater than the recurring yearly O&M costs of 

$130,000 (item 5 in table 3-1) for phytotechnology. Total costs for design, installation, operation, and maintenance of the 

baseline approach for twenty years is $6,994,520, which is approximately than $2.4 million greater than the 

phytotechnology approach ($4,592,632). 

xxxii 
SECTION 4

TREATMENT EFFECTIVENESS

4.1 Project Overview 

The 317/319 Area is located on the southern end of the ANL-E property. It contains a number of sites that were used 

before 1980 to dispose of a variety of solid and liquid wastes. These sites have been delineated and classified by IEPA 

as SWMUs and require corrective action pursuant to ANL-E’s RCRA Part B Permit. 

Past remedial investigations have identified two distinct plumes of contaminated ground water moving in a southeasterly 

direction below the 317/319 Area (Moos, 1997). One plume begins at the 317 French Drain (the suspected source area) 

and contains a mixture of chlorinated and aromatic VOCs. The other plume extends downgradient of the 319 Area Landfill 

and contains primarily tritium and some VOCs. Groundwater and leachate collection systems have been installed to 

intercept these plumes and prevent migration to a public forest preserve immediately south of the ANL-E boundary. 

A series of interim remedial actions were conducted in the 317/319 Area to initiate the cleanup process and reduce 

pollutant migration to the underlying ground water (Wozniak, 1998). The DOE Accelerated Site Technology Deployment 

program and EM-40 funded ANL-E to deploy a phytotechnology system to complete the restoration of the site. As 

described in section 1.1.6, phytotechnology is the purposeful use of living plants for in situ treatment of contaminated soil 

and ground water. The process acts as a system of abatement mechanisms that include some or all of the following: 

sequestration, removal, stabilization, degradation, and mineralization. In the instant case, ANL-E has chosen 

phytotechnology over the baseline pump-and-treat technology because it appears to be less costly and is thought to offer 

technical advantages such as active cleanup, less residual waste generation, and better operation in the complex 

stratigraphy of the site. 

During June and July 1999, ANL-E installed stands of hybrid poplars and hybrid willows and a supplemental ground cover 

of herbaceous plants with the following objectives: 

• Hydraulically contain the VOC and tritium plumes south of the 317 Area French Drain and 319 Area Landfill 

• Continue the remediation of residual VOCs within the 317 Area French Drain 

• Minimize water infiltration into the 317 Area French Drain soils and stabilize the surface to prevent erosion, runoff, 

and downstream sedimentation. 

Earlier in 1999, EPA expressed an interest in participating with DOE in this study and subsequently included it as a 

demonstration project under the National Risk Management Research Laboratory (NRMRL) SITE program. Through a 

written commitment between the two organizations, ANL-E and EPA agreed to share the responsibility for monitoring the 

system and evaluating its performance. 

xxxiii 
ANL-E anticipates an operating period of up to 20 years; EPA’s involvement covers the first three years of operations, from 

July 1999 through September 2001. A number of monitoring and measurement activities were planned, and these are 

described in section 4.3. 

4.2 Detailed Project Description 

4.2.1 317/319 Area 

ANL-E comprises more than wooded 600 ha (1,500 ac) approximately 40 km (25 mi) southwest of Chicago, Illinois. The 

317/319 Area occupies 2 ha (5 ac) at the southern end of the property. Figure 4-1 shows the location of ANL-E relative 

to the Chicago area (left) and the position of the 317/319 Area within the ANL-E campus (right). (Larger, easier-to-view 

versions of these maps are available at www.anl.gov.) 

The 317 Area French Drain, IEPA SWMU No. 11, is described as an active hazardous and radioactive waste processing 

and storage area. According to ANL-E, liquid chemical wastes were disposed of at this site during the 1950s in shallow, 

gravel-filled trenches (Moos, 1997). The types and volumes of products disposed of were not documented; however, they 

likely consisted of cleaning solvents, oils and lubricants, and laboratory chemicals. Over time, these chemicals migrated 

into the surrounding environment. Data show that VOCs were detected in soil and groundwater samples from the French 

Drain (various depths to 10.3 m, 34 ft) and the downgradient fence line at levels above applicable standards (Moos, 1997). 

These data are summarized in Table 4-1. 

Figure 4-1. Locations of ANL-E (left) and the 317/319 Area (right) 

xxxiv 
Table 4-1. Maximum 317 Area VOC Concentrations above Applicable Remediation Objectives 1 

Analyte 317 French Drain Soil 

(ug/kg)

 317 French Drain 

Ground water 

(ug/l) 

ANL-E Fence-line 

Ground water 

(ug/l) 

Benzene 3,200 (80)2 -- --

Carbon tetrachloride 54,000 (1,024)2 -- 8 (5) 4 

Chloroform 21,000 (1,670)2 380 (211)3 4 (0.02)4 

Methylene chloride -- -- 14 (5)4 

Tetrachloroethene 190,000 (152)2 50,000 (316) 3 --

Trichloroethene 47,000 (80) 2 8,600 (127)3 6 (5)4 

1,2-Dichloroethane -- -- 6 (5)4 

4-Methyl-2-pentanone 78,000 (28,200) 3 -- --

1

 Remediation objectives in parentheses

2

 Tier 2 value recommended by IEPA, March 1, 1999.

3

 Tier 2 value presented in Moos, 1997. 

4

 Tier 1 value presented in Moos, 1997.

– Data not collected 

The 319 Area Landfill, IEPA SWMU No.2, was previously operated as a solid waste landfill by the trench-and-fill method. 

Wastes disposed of within the landfill included general rubbish, construction and demolition debris, old equipment, metal 

scrap, wood, concrete, and other miscellaneous items. According to ANL-E, tritium and three VOCs were detected in 

groundwater samples from the southern tip of the landfill and the downgradient fence line at levels above applicable 

standards (Moos, 1998). These data are summarized in Table 4-2. 

Table 4-2. Maximum 319 Area Tritium/VOC Concentrations above or Equal to Applicable Remediation Objectives 1 

Analyte 319 Landfill Ground water 

(ug/l or pCi/l) 

ANL-E Fence line Ground 

water 

(ug/l or pCi/l) 

cis-1,2-Dichloroethene 240 (70)2 --

Trichloroethene 24 (5) 3 5 (5) 3 

Vinyl chloride 5 (2)2 --

Tritium 233,000 (20,000) 3 --

1

 Remediation objectives in parentheses 

2

 Tier 1 value presented in Moos, 1997. 

3

 35 IAC 620.410, Groundwater Quality Standards for Class 1 

– Data not collected 

xxxv 
4.2.2 Hydrogeology 

According to ANL-E, the subsurface within the study area is a complex arrangement of approximately 18 m (60 ft) of 

glacial deposits over dolomite bedrock (Quinn, 1999). The glacial sequence is comprised of two main bodies that are 

dominated by fine-grained, low-permeability till. Permeable zones of varying character and thickness are present in each. 

These materials range from silty sands to sandy, clayey gravels to gravelly sands. In some locations, pure silt was 

encountered. If deep enough, this silt was typically saturated, and it is assumed to play a role in the flow of ground water 

in the study area. The permeable zones have a wide range of shape, including thin, lenticular, alluvial deposits; thick plugs 

of possible slump or channel-fill material; interfingerings; and a thick, basal, proglacial sand and gravel. In general, the 

permeable units are poorly sorted and many of them may represent slope-induced mass movement, resulting in transport 

and mixing of sediments. Their thickness range from 0.3 m (1 ft) to more than 4.6 m (15 ft), and data suggest short lateral 

extent. 

The use of the term “aquifer” in this glacial setting is applied to any of the relatively permeable materials, including pure 

silt, and is not related to a permeable unit’s thickness, lateral extent, or ability to yield water at any certain rate. 

The focus of this demonstration is the uppermost contaminated aquifer. The depth to the top of this unit ranges from 6.7 

to 8.5 m (22 ft - 28 ft) in the 317 Area French Drain vicinity and 6.7 m to 10.4 m (22 ft - 34 ft) near the southern fence line. 

It is not a continuous feature in the study area. The aquifer is best described as numerous permeable subunits of varying 

character and geometry that share some similarity in depth and likely have some degree of hydraulic connection (Quinn, 

1999). Based on well data, aquifers above this unit are assumed to be clean south of the 317/319 Area, though aquifers 

below it are impacted somewhat by VOCs and/or tritium. 

Ground water in the aquifers flows generally to the southeast. ANL-E states that this is supported by head measurements 

reported in site investigation documents, and it is in keeping with the notion of regional flow following the topography and 

moving toward the Des Plaines valley. 

The aquifer of interest is assumed to receive input from upgradient sandy units to the northwest and from downward 

infiltration. The recharge from infiltration may be localized, originating from shallower perched aquifers or directly from 

precipitation and conveyed by fractures within the overlying till. 

The hydraulic conductivity determined from slug tests at monitoring wells throughout the 317/319 Area ranges from 4E-6 

cm s-1 to 6E-2 cm s-1 (0.01 ft day-1 - 170 ft day-1), with an average of 3.8E-3 cm s-1 (10.8 ft day-1). The slug tests indicate 

variable permeability across the site without any trend (Quinn, 1999). 

4.2.3 Climatology 

ANL-E and the greater Chicago area are in a region of frequently changeable weather. The climate is predominantly 

continental, characterized by wide seasonal temperature swings. This continentality is partially moderated by Lake 

Michigan, and to a lesser extent by the other Great Lakes as air masses gain or lose heat to the underlying water bodies. 

Very low winter temperatures most often occur in air that flows from the north, west of Lake Superior. High summer 

temperatures are the result of south or southwest flow not influenced by the lakes (GRC, 1977). Average maximum daily 

temperatures are highest during July (29 o

C, 84 oF) and lowest during January (-2 oC, 29 oF). 

There is a 50 percent likelihood that the temperature will fall to 0 o

C (32 oF) or lower by October 26, and that the last 

temperature of 0 o

C (32 oF) or lower in spring will have occurred by April 20. However, temperatures this low have been 

recorded as early as September 25 in autumn, and as late in spring as May 14 (GRC, 1977). The Illinois State 

Climatologist’s Office estimates that the median growing season for the area surrounding ANL-E is between 155 and 165 

days. Seasonal CDD (May through October) averages approximately 750 degree days (base 65). 

xxxvi 
Precipitation falls mostly from air that has passed over the Gulf of Mexico. Summer thundershowers are often locally 

heavy and variable; parts of the Chicago area may receive substantial rainfall and other parts none. Longer periods of 

continuous precipitation are mostly in autumn, winter, and spring. Annual precipitation averages approximately 91 cm (36 

in), of which about 48 cm (19 in) falls during the growing season (May through September). 

The amount of sunshine is moderate in summer and quite low in winter. A considerable amount of cloudiness, especially 

in winter, is locally produced by lake effect. Days in summer with no sunshine are rare. The total sunshine in December, 

partly because of shorter days, is only a little over one-third the July total (GRC, 1977). Annual pan evaporation (May 

through October) for the area is estimated at approximately 73 cm (29 in). 

4.2.4 Remedy Selection 

4.2.4.1 Interim Measures 

In 1997, ANL-E installed seven extraction wells at the southern fence line and just south of the 319 Area Landfill to 

intercept contaminated ground water. The wells capture a portion of these plumes along with uncontaminated ground 

water; the water collected, estimated at 26,500 L d-1 (7,000 gal d-1), is forwarded to Argonne’s treatment plant before being 

released. 

In 1998, ANL-E performed a voluntary interim corrective action on soils within the 317 Area French Drain. The goal was 

to remove the majority of VOCs from selected highly-contaminated areas with the intent that the larger, surrounding, 

lightly-contaminated area could be treated by another approach at a later date. The primary method of treatment was soil 

mixing combined with hot air/steam and vapor extraction. This technology was chosen because the soils are stiff glacial 

till and thought to require considerable (mechanical) energy to work the matrix and increase permeability. The secondary 

method was zero-valent iron injection in conjunction with further soil mixing. Removal rates in excess of 95% were 

reported (Lynch et al., 1998). 

4.2.4.2 Phytotechnology 

ANL-E decided against using DOE’s “baseline” technology, which would have involved installing an asphalt cap and 

adding additional extraction wells. ANL-E believed the site’s complicated subsurface would make it too difficult to predict 

where to place wells to produce a significant zone of influence. Instead, site managers chose phytotechnology. At the 

time, phytotechnology had been (at least on a limited basis) demonstrated feasible on VOCs in soil and ground water, and 

the following had already been shown or hypothesized about tritium: (1) tritium can be directly incorporated into water and 

biological tissues; (2) plants transpire tritiated water vapor; (3) tritium can accumulate in plant tissues, but the contaminant 

mean residence time is only about 4 to 37 days; and (4) contaminated ground water can be controlled using engineered 

plant-based systems. (Refer to section 3.5 for a comparison between the baseline technology and phytotechnology.) 

To gain regulatory approval for the phytotechnology project, ANL-E had to prove that the plants would not release 

hazardous quantities of airborne VOCs or tritium. Emissions were calculated using EPA’s CAP-88 (Clean Air Assessment 

Package-1988) exposure equations assuming worst-case scenarios. The highest concentrations detected in ground water 

after interim treatment were assumed to be in contact with and transpired by the plants. Emission levels were then 

calculated for an entire mature plantation with the expectation that transpiration rates would range from 8 to 190 L d-1 tree-1 

(2 to 50 gal d-1 tree-1), depending on the season. The results indicate that VOC and tritium emission rates would be 

several orders of magnitude lower than what is allowed under NESHAP. 

xxxvii 
4.2.5 Plantation Installation 

In June and July 1999, an engineered phytotechnology system was initiated and completed. It has the following 

components: (1) a herbaceous cover that is designed to minimize water infiltration and soil erosion; (2) shallow-planted 

TreeMediation® hybrid willows, which are intended to address the VOC source area; and (3) deep-planted TreeWell® 

hybrid poplars, which are expected to achieve hydraulic groundwater control. The latter were planted in lined columns 

where the roots are cut off from all shallow sources of water and are forced to grow downward in search of ground water. 

ANL-E stated that plume velocity and winter dormancy were considered when the number of trees to include in the 

phytotechnology design was determined. 

A total of 809 trees were planted across the 317/319 Area. The trees were nursery raised for two years by ANS using 

proprietary techniques to maximize root mass prior to delivery and installation. Some 200 willows were planted on 3-m 

centers (10-ft) directly over the foot print of the former 317 Area French Drain (317 FD). The mix of willow species 

planted include laurel (salix pentandra), golden weeping (salix alba ‘Niobe’) and the prairie cascade hybrid (salix x ‘Prairie 

Cascade’). A total of 481 poplar saplings were planted on 5-m (16-ft) centers south of the demolished 317 Area South 

Vaults and south of the 319 Area Landfill. These plantings are known as the hydraulic control areas (HCs). The mix of 

poplars planted included a hybrid species (populas charkowiiensis x incrassata, NE 308). An additional 128 poplars were 

planted to fill in gaps and extend the treatment area. In the southwest corner of the 317 HC, the extra poplars increase 

the density of the tree stand by halving the distance between plants, i.e. 2.5-m (8-ft) spacing. At least two rows of hybrid 

poplars were planted along the southern edge of the willow plantation just north of the still-active North Vaults. The poplar 

trees were planted on both sides of the chain-link fence bounding the southernmost perimeter of the 317 Area Radioactive 

Control Zone. South of this fence, rows of poplar trees extend about 49 m (160 ft) to the southern property line. 

Poplars in the 317/319 HC were planted in 9.1 m (30-ft) columns with the root mass installed to a depth of approximately 

3.0 m to 4.6 m (10 ft - 15 ft) bgs. The 0.6-m (2 ft) diameter columns have a 6-m (20-ft) plastic liner that reportedly "trains" 

the roots to develop in a downward direction past clean surficial aquifers (5 m, 16 ft bgs) toward the contaminated aquifer. 

ANS states that the root system can grow as much as several centimeters per day during the growing season. The hybrid 

willows in the 317 FD were planted in 3-m (10-ft) unlined wells, with the root mass installed just below ground surface. 

Without a liner, the root system is free (presumably) to develop horizontally as well as vertically throughout the soil volume 

so that the rhizosphere can reach and affect the soil contaminants. All columns were backfilled with layers of blended 

top soil (10% manure) and sand to provide nutrients and wick ground water to the developing roots. 

The 317 FD was seeded with a mix of legumes (Lotus corniculatus) and grasses (Lolium perenne and Phalaris 

arundinacea) to minimize water infiltration and stabilize the soil. Control cells were set up at the ANL-E greenhouse area 

to represent background conditions. 

Figure 4-2 is an “as-built” drawing of the planted system as of September 11, 1999. Note: While the legend and other 

details of this drawing are not legible, the location and extent of the plantations are clearly visible. The “x” symbols 

represent willow trees planted within the 317 FD. The “+” symbols represent poplar trees, which have been planted in 

a wide, generally continuous band below the 317 FD and 319 Landfill. For reference purposes, it should be helpful to 

the reader to compare figure 4-2 with figure 1-2 (photograph of the site taken at about the same time frame in which the 

drawing was developed) and figure 4-3, which is a schematic representation of the 317/319 Area. 

xxxviii 
Figure 4-2. As-built Drawing of 317/319 Area Plantations 

xxxix
4.2.6 Monitoring 

The monitoring system was designed to measure incremental changes in site conditions over time. The monitoring 

strategy for this study was more extensive than would be required for a typical phytotechnology project due to its research 

nature. Data collected for the monitoring program were used to determine how well the system performed during the 

demonstration period and to predict future system performance. The following monitoring stations were employed in this 

study: 

• Approximately 60 wells upgradient, within, downgradient of the 317/319 Area were used to calibrate a 

groundwater model (MODFLOW) to assess hydraulic control. 

• A total of 13 groundwater monitoring wells were sampled for selected VOCs, tritium, and other parameters. 

• Pressure transducers were installed in 7 monitoring wells, including 2 upgradient of and 5 within the planted area. 

• A weather station was installed to collect site-specific climate data 

• Thermal dissipation probes were used during the 2000 and 2001 growing seasons to measure sap flow in 

selected trees. 

Figure 4-3 (not to scale) depicts the location of monitoring points used by the SITE program with respect to the tree 

plantations, which are represented by the shaded rectangles. 

Figure 4-3. SITE Demonstration Monitoring Locations 

xl 
4.3 Project Objectives 

The deployment of phytotechnology at the 317/319 Area at ANL-E was studied to determine the ability of a purposefullyplanted tree system to reduce the hazards of past releases of solvent-type VOCs and tritium into the environment. For 

the term of this SITE demonstration (1999-2001) monitoring and assessment duties were shared between the ANL-E and 

EPA. During the program kick-off meeting held on April 7, 1999 at ANL-E, specific scientific and engineering project 

objectives were discussed, and tasks designed to generate the data required to evaluate those objectives were divided 

among the organizations. The objectives, collection methods, and evaluation results are presented in this section. 

4.3.1 Primary Objectives 

4.3.1.1 Groundwater Containment 

The first primary objective of this technology demonstration was to measure the sap flow of a small portion of the trees 

within the hydraulic control area and extrapolate the results stand-wide. The goal was to determine whether the 

extrapolated, stand-wide sap flow during the height of the second full growing season (2001) matches the estimated 

groundwater flow at baseline (1999). 

An important mechanism for this system is the containment of polluted ground water through the interception and removal 

of water from the aquifer of interest. It was hypothesized that containment is achieved if the hybrid poplars take up water 

(represented by sapflow measurements) at a rate at least equal to the groundwater flux beneath the tree stands. Implicit 

in this hypothesis were several assumptions: 

• The combination of deep planting and fast root growth would allow the plants to reach and establish the aquifer 

of interest as an unrestricted source of water (luxury consumption) at some point prior to the measurement 

period. 

• The lined caissons would prevent hydraulic contact with shallow, uncontaminated water-bearing units scattered 

throughout the 317/319 Area. 

• Based upon previous research and experience, ANS estimated that hybrid poplars in-ground for four years could 

transpire as much as 150 L d-1 (40 gal d-1). The ANL-E trees were in-ground for two years when sap flow was 

measured in 2001. 

• Trees planted in the area known as the 319 Waste Trench were not included because they do not intercept the 

aquifer of interest. 

Monitoring Protocol. SITE installed thermal dissipation probes (TDP-30, Dynamax, Inc., Houston, TX) on 20 hybrid 

poplar trees inside the 317 HC within 30 m (100 ft) of one of two data collection systems located 53 m (175 ft) apart. 

TDPs measure sap flow via the temperature difference between a (non-heated) reference probe and a heated probe that 

is cooled proportionally by the movement of the sap liquid. Figure 4-3 shows the relative position of the instrumented 

trees within the 317 HC. The trees were instrumented beginning June 28, 2001 and monitored through October 18, 2001 

(112 days). At the time of probe installation, all instrumented trees were greater than 30 mm in diameter (minimum 

requirement). The cross-sectional (basal) area of each instrumented tree was determined by measuring the trunk 

diameter at the point of probe insertion approximately 15 cm (6 in) above ground surface. Trunk diameter was measured 

along the north-south aspect and the east-west aspect and averaged to determine basal area. These measurements 

were made at the beginning of the data collection period and again the following spring (June 2002). The mean of these 

two values was used to calculate specific sap flow (i.e., sap flow normalized to basal area) for each instrumented tree. 

Basal area measurements for all hybrid poplars in the 317 HC and 319 HC were collected during June 2002 and used 

to extrapolate the mean sapflow rate from the 20 instrumented trees to the entire 317/319 HC tree stand (509 trees). 

xli 
SITE employed two remote data collection systems (AM 416 Multiplexer, Campbell Scientific, Inc., Logan, UT). Each 

system was powered by a 12-volt battery recharged by a 60-watt solar panel. A voltage regulator (AVRD, Dynamax, Inc.) 

maintained the output from the multiplexers to the TDPs at approximately 2.8 volts. Data from the 20 TDPs were 

collected at 10-second intervals. Sixty-minute averages and minimum and maximum values were recorded daily by a 

datalogger (CR10X Datalogger, Campbell Scientific, Inc. Logan, UT). Stored data were downloaded periodically by a 

site worker, generally on two-week intervals. SITE converted sapflow measurements to gross water use using methods 

outlined by Dynamax, Inc. The following notation is used to describe how stand-wide transpiration was determined. 

Define mean specific sap flow as x (g hr-1 cm-2), the mean of individual specific sapflow measurements, xi (g hr-1 cm-2), 

where 

x = xi 

1 ∑

ns

n (Eqn. 4-1) s i=1 

for i = 1,2,3..., ns instrumented trees. Define the basal area of the entire 317/319 HC tree stand as B (cm2), the sum of 

basal area measurements for individual trees, bi (cm2

), where 

np 

B= ∑bi (Eqn. 4-2) 

i=1 

for i=1,2,3..., np trees in the 317/319 HC tree stand. Define total sap flow as Y (g hr-1), where 

Y = x B (Eqn. 4-3) 

SITE compared total sap flow (after conversion to L day-1) using a statistical test of hypothesis to the estimate of baseline 

groundwater flux developed by Quinn (1999). 

4.3.1.2 Groundwater Contaminant Removal 

The second primary objective was to determine how effective the planted system could be in reducing the concentration 

of VOCs in the contaminated aquifer. 

In addition to hydraulic control, poplars have a demonstrated ability to remove a variety of compounds from ground water. 

For this study it was hypothesized that the trees would remove contaminated water from the aquifer by means of their 

root systems, followed by the physiological alteration and incorporation of some compounds within the tree stems or the 

transpiration and volatilization of others into the atmosphere. The trees would also promote microbially-mediated 

reductive dechlorination of dissolved CAHs within the aquifer. Implicit in this hypothesis were several assumptions: 

• The trees would establish contact with the saturated zone with ample time to influence subsurface geochemistry 

and promote reducing conditions. 

• Treatment of tritium is primarily from groundwater uptake and volatilization, with a fraction retained for a brief 

period of time within the plant stem. 

xlii 
• The effect of non-destructive attenuation mechanisms (dilution, dispersion, sorption, etc.) is not known, but is 

thought to be negligible. 

Monitoring Protocol. Data supplied by ANL-E from ongoing monitoring programs were used by SITE to identify a group 

of contaminants to be used in calculating VOC reduction. The top five VOCs were identified in terms of concentration and 

frequency of occurrence (i.e. lack of reported non-detects). These contaminants were (in descending order of 

concentration): 1,1,1-trichloroethane (TCA), 1,1-dichloroethane (DCA), cis-1,2-dichloroethene (DCE), chloroform (CLF), 

and trichloroethene (TCE). 

SITE collected groundwater VOC samples with a bladder pump using low-flow purging techniques (EPA, 1996b) to 

prepare the well. Samples were analyzed by (baseline) EMAX Laboratories, Torrance, CA and (final) Analytical 

Laboratory Services, Inc., Middletown, PA. All samples were analyzed by gas chromatography with flame ionization and 

election capture detection (GC/FID/ECD) according to EPA SW-846 Method 8021B (EPA, 1986). 

SITE collected one sample per day for six days from each of seven primary monitoring wells during the baseline sampling 

event (BSE, August 1999) and again during the final sampling event (FSE, June 2002). Consequently, a total of 42 

baseline and 42 final samples were available to evaluate the project objective. A number of sample results were also 

available from non-primary monitoring wells. These non-primary data in conjunction with the primary well data assist in 

shaping a better understanding of conditions throughout the study area. In addition, a limited data set was available for 

all monitoring wells from the mid-term sampling event (MSE). The MSE was conducted during November 2000; the 

timing and data from the event can add some perspective in gauging the progress of the system. 

There are five target analytes per sample (CLF, DCA, DCE, TCA, and TCE), which equates to 210 analyte results per 

data set. In the BSE data set 33 of 210 results were non-detect, and 19 of 210 results were non-detect in the FSE data 

set. Non-detect results were set equal to the reporting limit, generally 1 ug l-1. The concentrations of the five target 

analytes were summed to yield a “total VOC” concentration for each sample. 

SITE collected groundwater tritium samples with a disposable Teflon® bailer and shipped to and analyzed by (baseline) 

Barringer Laboratories, Golden, CO and (final) Paragon Analytics, Ft. Collins, CO. All samples were analyzed by liquid 

scintillation according to EPA Method 906.0 (EPA, 1980). 

SITE collected one sample per day for six days from each of two primary monitoring wells during the BSE and again 

during the FSE. Consequently, 12 baseline and 12 final samples were available to evaluate the project objective. All 

sample concentrations were above the reporting limit of 1,000 pCi l-1. 

4.3.1.3 Soil Contaminant Removal 

The third primary objective was to determine how effective the planted system could be in reducing the concentration of 

TCE in the 317 FD soils. 

In addition to poplars, willows also have a reported ability to remove a variety of compounds from soil-pore water. In the 

instant case, it was hypothesized that the trees would remove soil-pore water from the 317 FD soils by means of their 

root systems, followed by the physiological alteration of TCE within the trees or the transpiration and volatilization of TCE 

into the atmosphere. It was believed that the trees would also promote microbially-mediated reductive dechlorination of 

TCE. Implicit in this hypothesis were several assumptions: 

xliii 
• The tree roots can develop vertically and horizontally to reach and affect TCE throughout the 317 FD. 

• After the interim soil-mixing activities undertaken in 1998, the tight clay-like soil matrix does not hamper root 

growth or channel roots away from polluted areas via preferred growth pathways. 

• The residual levels of TCE and other contaminants are not toxic to the plants. 

Monitoring Protocol. SITE collected soil samples via Geoprobe® from 28 boreholes arrayed in regular spacings across 

the 317 FD. Composite samples were drawn from three different subsurface intervals: 4 ft to 8 ft (1.2 m to 2.4 m), 8 ft to 

12 ft (2.4 m to 3.6 m), and 12 ft to 16 ft (3.6 m to 4.9 m). SITE extracted the samples promptly onsite using methanol and 

then shipped to and analyzed by (baseline) EMAX Laboratories, Torrance, CA and (final) Analytical Laboratory Services, 

Inc., Middletown, PA. All extracts were analyzed by GC/FID/ECD according to USEPA SW-846 Method 8021B. Results 

were reported on a dry weight basis. 

SITE collected a total of 84 baseline and 84 final samples from the 317 FD producing a combined data set of 84 paired 

samples. A large number of non-detections were reported, including 43 of 84 and 46 of 84 in BSE and FSE data, 

respectively. All non-detect results were set equal to the reporting limit, which ranged from 4 to 69 ug kg-1. 

4.3.2 Non-primary Objectives 

Non-primary objectives were included in the study to elucidate the biological, hydrological, and biochemical processes 

that contribute to the effectiveness of the ANL-E deployment on contaminated ground water and soil. Since planted 

systems can take several years to become fully effective, much of the data associated with the non-primary objectives 

were collected to build predictive models to determine future performance. Measurements are primarily related to tree 

physiology (tree growth and contaminant translocation) and aquifer characteristics (hydraulic, geochemical, 

microbiological). Scientists at ANL-E and Science Applications International Corporation (SAIC) conducted the work 

related to the non-primary objectives in coordination with the EPA SITE program. 

Non-primary objectives and the scope of the associated data collected are described herein. 

4.3.2.1 Contaminant Uptake and Degradation in Plant Tissue 

While it is known (Gatliff et al., 1998; Newman et al., 1997) that trees such as poplars and willows are capable of taking 

up a number of organic compounds (including CAHs), there are varying opinions on the fate of those compounds in the 

rhizosphere and plant systems. These compounds can be degraded in the root zone (Nzengung et al., 2001), taken into 

the plant and vented through the bark (Burken and Ma, 2002), and degraded in leaf tissue (Newman et al., 1999). 

Portions of these contaminants have also shown to be vented out by the same trees into the air via the transpirative flow 

or, during winter, by gas diffusion through the plant’s air conducting tissue (Nietch et al., 1999; Vroblesky et al., 1999; 

Davis et al., 1998). 

ANL-E sampled plant tissues (leaves and stems) to determine the presence of VOCs and their degradation intermediate 

trichloroacetic acid (TCAA). Finding VOCs in leaf and/or branch tissue above background levels would provide a clear 

indication that the trees are indeed taking up the contaminants from soil or ground water and translocating it to the 

aboveground tissues. Finding TCAA in these tissues would provide proof that at least a portion of the parent compound 

is being degraded by the plant. In principle, by multiplying contaminant concentrations in the sap by sapflow rate, a 

measure of contaminant removal by plant uptake can be obtained. However, this is still a very imprecise measurement 

xliv 
because of unknown diffusion rates from the sap through cell walls into external air, and because it is still unknown how 

much of the total contaminant detected in tissue is in the freely moving sap and how much is adsorbed to the plant 

tissues. 

ANL-E collected samples of leaves and branches by cutting with sharp scissors and placing into airtight crimped 

headspace vials. Samples for VOC and TCAA analysis were directly placed into headspace vials for gas 

chromatographic analysis within 24 hours. While analysis of VOCs was conducted via direct headspace techniques, 

samples for TCAA analysis were thermally decarboxylated at 90<C before being analyzed via headspace. Control 

samples from plants growing in non-contaminated soil were also sampled and analyzed using the same methods. 

Detection limits were 0.5 ng g-1 for CLF, TCAA, TCE, and 0.2 ng g-1 for PCE. 

ANL-E collected samples from more than 30 different trees at the 317 FD area, plus willows at the greenhouse control 

plots, at various times during 1999, 2000, and 2001. In each sampling event, six samples were collected from each 

sampled tree, including two of branch tissue, and four of leaves growing on that branch. 

4.3.2.2 Geochemical and Microbial Indices of Reductive Dechlorination 

Davis et al (1996) in Chappell (1997) reports that microbial degradation of TCE can take place either aerobically or 

anaerobically. The aerobic process is an oxidative mechanism catalyzed by a mono-oxygenase enzyme. The anaerobic 

mechanism is reductive dechlorination, which is primarily carried out in the rhizosphere by methanogens. EPA (1998) 

suggests that reductive dechlorination is the most frequently encountered biodegradation mechanism in the subsurface. 

Furthermore, Bouwer (1994) in EPA (1998) reports that cis-1,2-DCE is a more common daughter product than either 

trans-1,2-DCE or 1,1-DCE. Baseline data from this project shows a preponderance of cis-1,2-DCE as compared to the 

other two congeners, which indicates that reductive dechlorination likely has occurred at the site. It was surmised that 

the action of the planted trees would re-activate the microbial population responsible for reductive dechlorination. 

Trees can induce subsurface oxygen utilization by providing organic matter that stimulates aerobic microbial activity and 

depletes oxygen levels. SITE collected geochemical samples to assess the development of subsurface anaerobic 

conditions over time, along with any associated reductive dechlorination of CAHs. SITE collected samples and 

measurements from monitoring wells and soil throughout the study area. BSE, MSE, and FSE groundwater field 

measurements include specific conductance, dissolved oxygen (DO), oxidation reduction potential (ORP), temperature, 

pH, and ferrous iron (Fe II); laboratory analyses include sulfate, nitrate, manganese, total iron, and dissolved organic 

carbon (DOC). The ratio of TCE to DCE is also examined. Soil measurements (unsaturated zone) include total organic 

carbon (TOC), manganese, iron and pH. 

SITE conducted a microbial survey to determine if the planted trees have driven the local microbial community structure 

to one that supports reductive dechlorination. SITE collected BSE and FSE samples of ground water and soil throughout 

the study area. Bacterial enumeration assays were performed for aerobic and anaerobic total heterotrophic plate counts 

by method 9215A/B (AWWA, 1971). Analyses of phospholipid fatty acids (PLFA) were performed to describe the classes 

of microbes present in the system and how they are reacting to environmental factors. PLFA analysis (White et al., 1997) 

is based on the extraction, separation, and recovery of lipid classes (Bligh and Dyer, 1959), followed by identification and 

quantitation using gas chromatography and mass spectrometry (GC/MS). 

4.3.2.3 Modeling and Confirming Water Use and Hydraulic Control 

As a means of evaluating the potential of the planted system for hydraulic containment, a finite-difference numerical flow 

model was constructed by at ANL-E Quinn et al. (2001). This model uses the U.S. Geological Survey code MODFLOW 

xlv 
(MacDonald and Harbaugh, 1988) and focuses on the confined, perched, glacial drift aquifer that extends below much 

of the 317/319 Area at a depth of approximately 7.6 m (25 ft) bgs. Modeling was directed initially toward calibrating to 

seasonally changing hydraulic heads based on over ten years of water level measurements at site wells. The effect of 

the ANS TTTS® of the plantation was then incorporated by assuming a best estimate for the water use of the trees under 

luxury consumption conditions. Both the growth phase and the mature phase of the plantations were modeled. ANL-E 

has developed a website that allows viewing of animated results of groundwater flow modeling in support of the 317/319 

Area phytosystem. The website address is http://web.ead.anl.gov/phyto/. 

In November 1999, as part of the phytotechnology system-monitoring program, SITE installed seven water level sensors 

(Druck model PDCR 1830, New Fairfield, CT) in monitoring wells in the 317 and 319 Areas. The water level data, along 

with weather station data, were collected hourly at several battery or solar-powered data loggers and were used by ANL-E 

to verify the validity of the predictions generated by the groundwater model. 

4.3.2.4 Health and Growth of the Planted System 

ANL-E monitored tree vitality by periodically measuring the height of the above ground stem (or tallest branch) and the 

diameter of the stem at 30 cm (1 ft) above ground level. ANL-E randomly selected approximately 10% of the trees for 

these measurements. ANL-E also carried out visual inspections were also carried out throughout the year to monitor 

aspect, presence of leaves, and branching, mortality, and presence of insects or other pests on the trees. 

Three observation areas for the herbaceous cover were also randomly chosen and established. ANL-E conducted 

observations periodically and included the determination of percent plant cover versus bare soil, and percent coverage 

for each herbaceous species. From a reference tree center, using a sighting compass, a measuring tape was directed 

outwards at 160/ from the tree. A 1-m2

 rigid quadrant (the survey area) was then placed on the ground, parallel to the 

tape on its west side at 1 m from the tree. The percent cover was defined as the amount of ground surface covered by 

living parts of plants, including but not limited to leaves. 

4.4 Performance Data 

The following sections present a discussion of the technology's performance with respect to the primary and non-primary 

project objectives. The purpose of the following sections is to present and discuss the results specific to each objective, 

provide an interpretive analysis from which the conclusions are drawn, and, if relevant, offer alternative explanations and 

viewpoints. 

4.4.1 Primary Objectives 

4.4.1.1 Groundwater Containment 

TDP data were evaluated per manufacturer’s guidelines. Some data were found unusable due to factors that led to 

extraneous or negatively reported numbers. Factors that may have caused data glitches include a poorly charged battery, 

cross signaling within the lines, and shorts within the system from electrical pulses or broken wires. Each data set was 

checked carefully for daily fluctuations and cross-checked against evapotranspiration data. Erroneous data were 

excluded from water use calculations. Four probes (N48, P96, R0, and T16) continuously reported negative or extreme 

values that did not correspond with evapotranspiration (e.g. night-time sap flow). Consequently, data from these trees 

were not used to assess groundwater containment. 

Average transpiration (L day-1) for each tree measured during the 2001 monitoring period is presented in Table 4-3. The 

results show that cumulative water use was highest during the month of July (62.5 L day-1). Accordingly, transpiration 

rates from July 2001 were used to evaluate the project objective. 

xlvi 
The June 2002 survey of the 317/319 HC poplars (509 trees) generated a cumulative, stand-wide basal area of 8,592 

cm2

. This area combined with the July 2001 transpiration data yields a mean stand-wide transpiration of 1,440 L day-1, 

with a 90% confidence interval between 1,270 L day-1 and 1,610 L day-1 (see p. 4-10 for calculation method). The 

underlying baseline groundwater flux was estimated previously by Quinn (1999) to be 4,870 liters day-1. Thus, the mean 

July 2001 transpiration rate was approximately 30% of the baseline groundwater flux. (A statistical test of hypothesis ("

= 0.10) confirmed statistically that the 317/319 HC plantation did not reach its target.) 

Table 4-3. Transpiration Rates for Instrumented Trees during 2001 Growing Season 

Tree ID 

Month N32 P64 P112 Q24 S32 T72 T256 U200 

July 0.95 6.76 2.55 1.33 2.09 2.58 6.61 5.62 

August 0.72 4.71 2.20 1.52 2.70 2.66 6.80 6.69 

September 0.65 3.72 2.28 1.33 2.20 2.20 5.13 5.02 

October 0.53 4.56 2.36 1.06 1.63 2.20 3.69 2.47 

N192 O200 O248 Q200 S176 S224 T160 T208 

July 2.39 6.23 2.32 4.86 2.89 2.70 7.87 4.75 

August 2.85 5.55 2.96 3.42 2.58 3.53 5.85 5.09 

September 1.98 3.61 1.98 2.39 0.80 2.51 3.50 4.67 

October 0.80 1.48 1.60 1.37 1.14 1.90 3.61 2.36 

Sum Mean 

per Tree 

July 62.50 L day-1 3.9 L day-1 

August 59.83 L day-1 3.7 L day-1 

September 43.97 L day-1 2.7 L day-1 

October 32.76 L day-1 2.0 L day-1 

Transpiration rates for individual trees during July 2001 range from 0. 95 L day-1 to 7.9 L day-1 with an average value 

of 3.9 L day-1. Not surprisingly, these rates were substantially below the ANS estimate of 150 L day-1 for poplars four 

years in-ground, which suggests that (1) the plants are not fully mature, and (2) the plants have not yet established luxury 

consumption conditions. However, Table 4-4 informs on encouraging year-to-year gains in transpiration rates despite 

the restricted water availability. Preliminary sapflow measurements were made on a sampling of 317 HC poplars from 

August 4 to September 18, 2000. This was a trial run for the purpose of testing the methods of installation and data 

gathering prior to the 2001 growing season when critical data would be generated. Table 4-4 compares the average 

transpiration rate from this trial period to a similar period during the 2001 study. Results show that the transpiration rate 

increased for individual trees between 0.2% (P64) to 81% (S32) with a cumulative increase of 18%. It is anticipated that 

the average year-to-year increases in transpiration will improve significantly once the plant roots are fully established in 

the saturated zone. 

A plot of mean results from the 2001 study (July-October) describes a modest correlation between basal diameter and 

transpiration rate (Figure 4-4). Further confirmation of this relationship after luxury water consumption conditions have 

been established may provide in future years a rough estimate of stand-level transpiration without direct sapflow 

measurements. 

xlvii 
Table 4-4. Sapflow Change between 2000 and 2001 

Tree 

Number 

Mean Sap 

Flow 2000 

Mean Sap 

Flow 2001 

Increase 

in Sap 

Rate 

N32 0.54 0.70 30% 

P64 4.73 4.74 0.2% 

P112 1.89 2.22 17% 

S32 1.17 2.12 81% 

T72 1.98 2.43 23% 

Total 10.31 12.21 18% 

0 5 10 15 20 25 30 35 40 45 

Basal Area (cm2) 

Figure 4-4. Relationship between July-October 2001 Sap Flow and Mean Basal Area 

SITE calculated daily PET with REF-ET software (Allen, 2000) using data obtained from a weather station located at ANLE. Values for PET were paired with daily water use and regressed. This was done for each instrumented tree for the 

2001 growing season. Results show weak-to-moderate correlations between PET and transpiration rate with coefficient 

Mean Vt (

L/day) 0 

1 

2 

3 

4 

5 

6 

7 

8 

xlviii 
of determination (r2

) values ranging from 0.09 to 0.65 (data not shown). This is further evidence that unrestricted water 

use conditions have not been established. 

4.4.1.2 Groundwater Contaminant Removal 

Data are summarized in Tables 4-5 (VOCs) and 4-6 (tritium), and figure 4-5 compares BSE and FSE VOCs concentrations 

at each of the groundwater sampling locations across the study area. 

VOCs: Baseline Conditions. Well construction information and the observed minimal difference in measured water levels 

(less than 1.5 ft / 0.5 m) at project outset suggest that the five wells within, upgradient, and downgradient of the 317 FD 

are situated in the same water bearing unit (data not shown). As such, the differences in groundwater total VOC 

concentration across the 317 FD at baseline are thought to be attributable mainly to the VOC content of the soil 

surrounding each well. For example, the baseline level of TCE in ground water at 317322, 317332, 317342, and 317422 

was 4.3, 0.38, 0.09, and <0.001 mg l

-1 (non-detect), respectively. TCE in soil sampling locations adjacent to each well 

was 47, 1.5, 0.24, and <0.061 mg kg-1 (non-detect). 

Well construction information and measured water levels of the five monitoring wells within and upgradient of the 317 HC 

suggest greater variability in aquifer physical characteristics. Well completion depths range from 27.6 ft / 8.4 m (317181) 

to 42.5 ft / 13 m (317172), and water levels were between 16.9 ft / 5.2 m (317151) and 30.8 ft / 9.4 m (317172). Baseline 

VOC concentrations also varied widely. Wells 317452 near the beginning of the HC plantation and 317221 near the end 

of the stand had low total VOCs levels of 0.0053 mg l-1 and 0.35 mg l-1, respectively. In contrast, 317151 and 317181, 

both located in the center of the 317 HC, had much higher total VOC concentrations, 62 mg l

-1 and 8.2 mg l-1, respectively. 

In general, baseline total VOC levels in the vicinity of the 317 HC do not appear to be spatially correlated. 

Information for the three monitoring locations within and upgradient of the 319 HC suggest that the wells may be located 

in two different water bearing units. Well 319261 appears to be screened in a shallower aquifer because its completion 

depth (17 ft / 5.2 m), which presumably represents the bottom of the formation, is above the water level of 319171 (26.8 

ft / 8.2 m) and MW007 (22.9 ft / 7.0 m). Baseline concentration of total VOCs was low for all three wells, as expected, 

ranging from 0.28 mg l-1 (319171) to 0.010 mg l-1 (319261). 

VOCs: Changes in Concentrations. A comparison of BSE and FSE data for the four monitoring locations within and 

downgradient of the 317 FD shows that the concentration of total VOCs increased in two wells (317322 and 317332) and 

decreased in two locations (317342 and 317432). The upgradient well that serves as a control (317422) remained 

constant at a non-detect level (<0.005), as anticipated. Table 4-7 shows mean water level data collected during the 

periods when groundwater wells were sampled by SITE. In general, changes in water column size are small and do not 

appear to have an impact on the interpretation of groundwater analyte data. 

The increase in total VOCs in 317322 was attributable to a single compound, DCE. The other four target analytes 

exhibited moderate to strong declines ranging from 36% (DCA) to over 99% (TCA). There is geochemical and biological 

evidence that the decreases in these analytes were brought about microbially under sulfate-reducing conditions (turn to 

section 4.4.2.2). Such an environment is generally conducive to dechlorination of each of the target analytes. The 

increase in DCE is thought to stem from coincidental leaching from the surrounding soil matrix, which is known to contain 

substantial amounts of the analyte (data not shown). Aerobic conditions (>1.0 mg l-1) were observed at 317332 during 

the study period (section 4.4.2.2). Aerobic conditions preclude the possibility of reductive dechlorination. Increases in 

concentration, possibly due to transport processes, were noted for each target analyte. The slight decrease in total VOCs 

observed at 317342 from 2.6 mg l-1 to 2.4 mg l-1 is probably an artifact of analytical variability. The decline in total VOC 

levels at 317432 (0.31 mg l-1 to 0.12 mg l-1) involves comparatively minor pollutant levels; however, the decrease between 

the BSE and FSE sampling events (61%) is significant (" = 0.10) when evaluated by single factor analysis of variance 

(ANOVA), where n=6 for each data set (means only shown in Table 4-5). The underlying attenuation mechanisms are 

xlix 
Table 4-5. Mean Target VOC Concentration in Ground water (mg l-1) 

Above 317 FD West of 317 HC 

317422 317172 

Analyte BSE MSE FSE BSE MSE FSE 

TCA <0.001 <0.001 <0.001 0.004 <0.001 <0.001 

DCA <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 

CLF <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 

DCE <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 

TCE <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 

Total <0.005 <0.005 <0.005 0.008 <0.005 <0.005 

Within and below 317 FD 

317322 317332 317342 317432 

Analyte BSE MSE FSE BSE MSE FSE BSE MSE FSE BSE MSE FSE 

TCA 8.3 0.68 0.030 3.7 4.8 13 1.9 1.9 1.5 0.18 0.073 0.065 

DCA 3.7 3.1 2.4 1.3 2.6 2.8 0.57 0.90 0.77 0.13 0.060 0.049 

CLF 12 12 2.0 0.0093 0.0076 0.028 0.0091 0.0030 0.0026 <0.001 <0.001 <0.001 

DCE 6.4 15 42 1.2 1.4 2.0 0.074 0.052 0.083 <0.001 <0.001 <0.001 

TCE 4.3 5.3 2.1 0.38 0.40 0.76 0.090 0.058 0.069 <0.001 <0.001 <0.001 

Total 34 36 49 6.6 9.2 19 2.6 2.9 2.4 0.31 0.14 0.12 

Within 317 HC 

317151 317181 317221 317452 

Analyte BSE MSE FSE BSE MSE FSE BSE MSE FSE BSE MSE FSE 

TCA 48 15 19 5.3 3.6 5.6 0.11 0.37 0.73 <0.001 <0.001 <0.001 

DCA 9.9 1.6 3.8 2.5 2.3 3.8 0.22 0.56 0.36 0.0013 0.0038 <0.001 

CLF 0.32 0.052 0.21 0.020 0.014 0.048 0.0011 0.003 0.0087 <0.001 <0.001 <0.001 

DCE 0.61 0.098 0.17 0.11 0.042 0.39 0.0041 0.0067 0.015 <0.001 <0.001 <0.001 

TCE 2.9 2.1 1.6 0.27 0.43 0.72 0.012 0.0054 0.13 <0.001 <0.001 <0.001 

Total 62 19 25 8.2 6.4 11 0.35 0.99 1.2 0.0053 0.0078 <0.005 

Above and within 319 HC 

MW007 319171 319261 

Analyte BSE MSE FSE BSE MSE FSE BSE MSE FSE 

TCA 0.015 0.011 0.015 0.24 0.28 0.18 0.0056 0.0058 0.0081 

DCA 0.0014 0.0022 0.0011 0.036 0.040 0.015 <0.001 0.0014 0.0013 

CLF <0.001 <0.001 <0.001 0.0017 0.0014 <0.001 <0.001 <0.001 <0.001 

DCE <0.001 <0.001 <0.001 0.0015 0.0016 0.0011 <0.001 <0.001 <0.001 

TCE <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 

Total 0.019 0.016 0.019 0.28 0.32 0.19 0.010 0.010 0.012 

l 
Table 4-6. Mean Tritium Concentration in Ground water (pCi l-1) 

Well BSE MSE FSE 

Within 319 HC 

319171 

319261 

Average 

MW007 

10,400 6,600 

3,700 2,000 

7,000 4,300 

Upgradient 319 HC 

3,000 2,200 

2,600 

1,200 

1,900 

3,100 

Figure 4-5. Baseline and Final Concentration of Target VOCs 

li 
Avg BSE 

Water 

Well Depth, Table, 

Well No. BTOC (ft) BTOC (ft) 

317322 30.3 20.2 

317332 36.4 20.2 

317342 37.9 21.6 

317432 37.9 20.5 

317151 31.7 16.9 

317181 27.6 19.7 

317221 36.8 29.3 

317452 37.0 20.2 

MW007 34.8 22.9 

319171 28.3 26.8 

319261 17.0 15.9 

317422 36.9 20.2 

317172 42.5 30.8 

Table 4-7. Water Column Sizes for Sampled Monitoring Wells 

BSE Water 

Column, (ft) 

Avg MSE 

FSE Water 

Column, (ft) 

Avg FSE 

Water Water 

Table, Table, 

BTOC (ft) BTOC (ft) 

317 French Drain 

10.1 

16.2 

16.3 

17.4 

21.0 9.3 

14.1 

13.9 

14.8 

20.1 1% 

22.3 16.9 20% 

24.0 19.8 11% 

23.1 19.4 6% 

317 Hydraulic Control 

14.8 

7.9 

7.5 

16.8 

18.3 13.4 

6.7 

7.0 

37.0 

18.1 -8% 

20.9 19.3 5% 

29.8 28.6 10% 

19.1 7% 

319 Hydraulic Control 

11.9 

1.5 

1.1 

34.8 23.9

0.5 

1.9 

-8% 

27.8 26.6 13% 

15.1 13.7 200% 

Above 317 FD and West of 317 HC 

16.7 

11.7 

36.9 19.1

42.5 

7% 

28.0 24% 

FSE Water 

Column, (ft) % Change 

10.2 

19.5 

18.1 

18.5 

13.6 

8.3 

8.2 

17.9 

10.9 

1.7 

3.3 

17.8 

14.5 

not known specifically, but geochemical and biological indices imply that the analytes may be undergoing dechlorination 

under weak reducing conditions. Overall, the concentration of total VOCs at monitoring locations within the 317 FD still 

appears at this stage to be influenced primarily by the elevated analyte levels in the surrounding soils. 

Data from monitoring wells within the 317 HC also indicate mixed performance. Locations 317181 and 317221 

demonstrate small magnitude gains in all or most individual compounds culminating in significant (" = 0.10 ) total VOC 

increases of 34% and 240%, respectively. In contrast, 317151 exhibits decreases in all analyte levels with a significant 

(" = 0.10) drop (60%) in total VOCs from 62 mg l-1 to 25 mg l-1, although the nature of the attenuation mechanism(s) is 

unclear. Control well 317172 located upgradient (to the west) of the 317 HC maintained near non-detect VOC levels 

throughout the demonstration, as anticipated. Location 317452 also maintained near non-detect VOC concentrations. 

Its placement within the 317 HC in relation to the general direction of groundwater flow makes it likely to receive water 

from a relatively clean source. 

In the 319 HC, the concentration of total VOCs in the upgradient well MW007 was unchanged (0.019 mg l-1), as expected. 

Well 319171 exhibits small declines in each of the target analytes detected combining for a modest drop (32%) in total 

VOCs from 0.28 mg l

-1 to 0.19 mg l-1. The attenuation mechanisms are unclear; the geochemical and biological 

parameters point to the presence of both aerobic and anaerobic conditions (turn to section 4.4.2.2). At 319261 small 

increases in the analytes detected result in a 20% gain, from 0.010 mg l-1 to 0.012 mg l-1. It is suspected that a portion 

of the difference in baseline/final analyte concentrations at these two monitoring locations can be explained by normal 

analytical variability. 

VOCs: Evaluation of the Project Objective. To evaluate the project objective, SITE examined BSE and FSE data from 

seven monitoring wells across the 317 FD and HC: 317151, 317181, 317221, 317322, 317332, 317342, and 317432. 

lii 
Collectively the mean concentration of target VOCs changed only slightly between the BSE (16.3 mg l-1) and FSE (15.2 

mg l-1). A statistical test of hypothesis (" = 0.10) showed that the suggested SITE reduction target (95%) for the 317 Area 

ground water was not yet achieved. 

Tritium: Evaluation of the Project Objective. To evaluate the project objective, SITE examined BSE and FSE data from 

the two monitoring wells within the 319 HC, 319171 and 319261. Collectively, the mean concentration of tritium decreased 

from 7,000 to 1,900 pCi l-1, a 73% reduction. The results were evaluated using a statistical test of hypothesis (" = 0.10) 

that concluded the suggested SITE reduction target (95%) for the 319 HC ground water was not yet achieved. 

The mean BSE and FSE data combined with the elapsed time between sampling events (1022 days) yield a tritium half-life 

of 540 days, according to the following relationship: 

T1⁄2 = -0.693 t / ln (Af

 / Ab) (Eqn. 4-4) 

where T1⁄2 is the half-life (days), t is the elapsed time (days) between activity measurements, Ab is the baseline activity, 

and Af

 is the final activity. When the data sets from 319171 and 318261 are investigated separately, both produce 

similar half-lives of 510 and 620 days, respectively. These are periods much shorter than the commonly-held 

standard for tritium of approximately 12.3 years or 4,500 days (Merck, 1989). In contrast, a single check sample 

(3,100 pCi l-1) collected from MW007, a control well located upgradient of the 319 HC, exhibited essentially no change 

from the baseline mean (3,000 pCi l-1). These results suggest that tritium is being removed from the system in 

addition to decreasing by natural decay. 

4.4.1.3 Soil Contaminant Removal 

Baseline Conditions. Figure 4-6 shows baseline and final TCE concentrations in a way that approximates the layout 

of the soil bore locations within the 317 FD. For example, SB#01 was physically located near the northwest corner of 

the 317 FD, and SB#28 was located in the southwest corner. The 317 FD Control Plot (317 FDCP) is a small (unplanted) 

parcel located just above the northwest corner of the 317 FD. Inspection of figure 4-6 provides the following observations: 

• Most TCE detections reside along the borders of the 317 FD from the northwest corner down along the western 

edge and then across the southern border to the southeast corner. 

• The area of heaviest contamination is along a large portion of the southern border, particularly within the 

subsurface interval from 8 ft to 16 ft (2.4 m - 4.9 m). 

• With the exception of some scattered detections, the northern and eastern borders and the central portion of the 

317 FD are mostly free of quantifiable amounts of TCE. 

Evaluation of the Project Objective. Originally, reductions in TCE soil concentrations were to be evaluated within the 

context of root density measurements. At the outset of the project it was surmised that meaningful reductions in TCE 

would be observed only where roots had developed to an extent where (1) roots could contact and uptake TCE entrained 

in soil-pore water, or (2) conditions for rhizodegradation could be established. However, over the course of the 

demonstration period, no reliable, standardized procedure could be identified for collecting root density samples at depths 

to 16 ft (4.9 m) bgs. Therefore, the evaluation of soil contaminant removal, as originally envisioned, could not be 

performed. Nonetheless, SITE collected FSE samples in order to document changes, if any, in soil TCE concen tration. 

Results show that the mean concentration of TCE increased 23% between the BSE (3.4 mg kg-1) and FSE (4.2 mg kg-1). 

A similar evaluation (non-primary) was performed on PCE, a TCE precursor. Analytical results also demonstrate little 

movement, with mean baseline and final concentrations of 5.4 and 5.5 mg kg-1, respectively (data not shown). 

liii 
Control Plot 

SB#29 SB#30 

BSE FSE BSE FSE 

4ft-8ft 56 56 63 56 

8ft-12ft 59 59 59 58 

12ft-16ft 59 59 61 58 

317 Area French Drain 

SB#01 SB#02 SB#03 SB#04 SB#05 

BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE 

4ft-8ft 540 360 800 63 58 69 110 57 59 55 

8ft-12ft 630 1,400 4,000 63 64 58 56 58 64 57 

12ft-16ft 130 270 12,000 77 61 57 62 61 62 58 

SB#06 SB#07 SB#08 SB#09 SB#10 

BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE 

4ft-8ft 8,600 12,000 63 61 62 61 65 56 59 58 

8ft-12ft 11,000 7,500 61 4,500 64 61 66 58 57 56 

12ft-16ft 3,000 6,200 61 4,200 66 62 66 65 61 66 

SB#11 SB#12 SB#13 SB#14 SB#15 SB#16 

BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE 

4ft-8ft 110 790 200 32 60 63 60 62 75 59 58 58 

8ft-12ft 370 720 1,900 14 63 63 60 57 59 64 57 59 

12ft-16ft 65 360 5,400 3,100 1,100 3,800 450 210 50 57 1,500 770 

SB#17 SB#18 SB#19 SB#20 SB#21 SB#22 

BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE 

4ft-8ft 140 430 51 61 50 62 61 63 68 62 58 57 

8ft-12ft 420 680 73 99 50 57 62 64 60 55 2,200 62 

12ft-16ft 120 190 50 4 48 57 71 64 59 59 4,800 2,000 

SB#23 SB#24 SB#25 SB#26 SB#27 SB#28 

BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE BSE FSE 

4ft-8ft 3,500 2,400 65 420 18,000 840 7,000 72,000 1,300 2,600 570 590 

8ft-12ft 2,800 590 59 61,000 25,000 810 40,000 60,000 21,000 17,000 620 4,000 

12ft-16ft 2,100 3,300 61 50,000 22,000 530 47,000 20,000 31,000 6,600 240 59 

Units in ug kg-1 Figures in bold type are above reporting limit 

Figure 4-6. Mean TCE Concentration in 317 French Drain 

liv 
Nonparametric Test of TCE and PCE Soil Results. The findings of parametric statistical analysis of the results can 

be influenced by erratic or inhomogeneous measurements. The 317FD TCE and PCE soil measurements for both 

baseline and final assessment show a relatively large proportion of nondetections together with a relatively small number 

of measurements at large concentrations. In the parametric statistical analysis, these large measurements can have large 

effect on sample mean values and standard errors. 

A nonparametric, descriptive assessment of the TCE and PCE demonstration measurements is presented. This 

nonparametric assessment cannot be unduly dominated by a small set of large values. However, it is not a useful 

approach to estimate the percentage magnitude of pollutant reduction. 

For this assessment, samples are paired uniquely across the BSE and FSE episodes by soil bore location and subsurface 

interval. If both members of the pair are nondetect, then the given sample pair exhibits “no change”; the sample pair 

exhibits an “increase” if the pollution concentration is larger at the FSE than the BSE; and otherwise, the pair exhibits a 

“decrease.” The respective pair sample counts are displayed in Table 4-8. 

For TCE, 37 of the 84 sample pairs showed no change, and there were 23 pairs with an increase in pollutant 

concentrations and 24 with a decrease. For TCE, these results provide no indication that there is a positive removal on 

a sample pair basis. 

For the 84 PCE measurements, 18 showed no change, 24 showed an increase, and 42 or half the measurements 

indicated a decrease (data not shown). This lends, at best, a marginal showing that the technology demonstrates a trend 

of positive removal on an individual sample pair bases, irrespective of the absolute or percentage magnitude of the 

removals. 

Table 4-8. Comparison of Baseline and Final Sample Pairs for French Drain Soils 

Sample Count PCE TCE 

Number sample pairs with no change 18 37 

Number of sample pairs with increase 24 23 

Number of sample pairs with decrease 42 24 

Total number of sample pairs 84 84 

4.4.2 Non-primary Objectives 

4.4.2.1 Contaminant Uptake and Degradation in Plant Tissue 

Plant tissue analyzed for VOCs and their degradation product TCAA show that the willows at the 317 FD started in the 

1999 growing season to take up and degrade these contaminants, and continued throughout the three growing seasons 

at rates that were very specific to each tree analyzed (data not shown). In general, the levels of contaminants and TCAA 

were consistently and significantly higher than background (as measured in the control trees) in the trees growing at the 

317 FD. TCE and PCE were found rarely in the leaf tissue, but consistently in the branch tissue. TCAA in contrast, was 

found exclusively and consistently in leaf tissue, where it accumulated throughout the summer, typically peaking late in 

the season, and then reverting to background levels in dead leaves approximately three months from their abscission 

from the tree. These observations support the hypothesis that contaminants are transported with the ascending sap to 

the leaves, where they are degraded to TCAA and subsequently mineralized. 

TCE concentrations in branches varied between non-detect and 301 μg g-1 on a dry weight basis. PCE also varied 

significantly, between non-detect and 600 μg g-1. TCAA was found in the large majority of leaf samples from the 

contaminated area. For a number of trees a strong, positive correlation was found between TCAA levels in the leaves 

lv 
and TCE and/or PCE in the corresponding branches at least for subsets of time. Many of these trees were spatially 

related. A few trees showed relatively elevated levels of TCAA, but quite lower levels of parent compounds, and no 

correlation between them. This points, among other hypotheses, to the potential presence of other contaminants in the 

soil that are not currently monitored but could degrade to TCAA. 

The importance of understanding the kinetics of TCE/PCE metabolism and the quantitative correlation between the TCAA 

and the parent compounds is fundamental to a correct prediction of contaminant uptake and degradation. However, while 

the data obtained so far clearly confirm plant uptake and at least partial degradation of the contaminants, more work is 

needed to determine sufficiently accurate removal rates, and the relationship between kinetics of TCAA formation and 

further degradation and environmental conditions such as radiant energy, ambient temperature, relative humidity, stomatal 

conditions, sap velocity, and general plant metabolic rates. For the time being, it is prudent to state that the willows in 

the 317 FD area are exerting a positive effect on contaminant removal. This effect is expected to be quantitatively more 

significant as the amounts of contaminated soil-pore water that is taken up and processed by the plants increases with 

plant size. 

4.4.2.2 Geochemical and Microbial Indices of Reductive Dechlorination 

Ground water. SITE used geochemical data as indicators of terminal electron acceptor processes occurring in ground 

water across the study area. The electron acceptor data includes DO, manganese, nitrate, ferric iron, and sulfate. Other 

measurements such as ORP, specific conductance, pH, and TOC provide additional information concerning 

biodegradation processes and changes in water chemistry associated with site hydrology. The results are summarized 

in Table 4-9; Table 4-10 and Figure 4-7 (both adapted from EPA, 1998 and Byl and Williams, 1999) were used in the 

interpretation of the data. It should be stressed that the criteria contained in table 4-9 and figure 4-7 should be viewed 

as general guidelines. 

317 FD. Because the overall direction of groundwater flow and the general extent of the contaminant plume are known, 

an attempt was made to identify discrete redox zones along the flow path of the aquifer of interest. The delineation of 

redox zones, supplemented by analyte chemistry data, was used to infer which VOC reduction process, if any, prevailed 

along the plume. 

Conditions in control well 317422 were aerobic during the study period with moderate levels of DO (2.0 to 2.5 mg l-1) and 

a positive ORP (4 to 67 mV). Since it is located upgradient of the source area, 317422 contained no detectable levels 

of the target analytes, as anticipated. The wells located along the flow path downgradient of 317422, sequentially 

317332, 317342, and 317432, contained progressively lesser concentrations of DO (1.7 to 0.64 mg l-1, FSE) and total 

VOCs (19 to 0.12 mg l-1, FSE). ORP measurements between locations fluctuated during the study period, but were within 

the range of possible reducing mechanisms. The following conclusions can be drawn about the downgradient wells: 

• 317332 was consistently aerobic with DO levels above 1.0 mg l-1. Aerobic conditions preclude reductive 

dechlorination from occurring since oxygen is the preferred electron acceptor. The concentration of total VOCs 

increased over time, conceivably due to transport from the surrounding soil matrix. 

• With DO levels below 1 mg l-1, an ORP between 110 and 130 mV, and a low concentration of nitrate (<0.2 mg 

l

-1), mildly reducing conditions (e.g., nitrate reducing) may be present at 317342. Changes in VOCs were slight, 

but the movement is consistent with mild reducing conditions in that the concentration of more oxidized species 

(TCE, TCA, and CLF) decreased, while less oxidized species (DCE, DCA) accumulated. 

• As the flow path proceeds downgradient to 317432, the concentration and trend of electron acceptors imply that 

nitrate reducing conditions may be present. However, the decrease and disappearance of DCA and DCE 

suggest that other attenuation mechanisms are also acting upon the contaminant plume. 

lvi 
Table 4-9. Mean Groundwater Geochemical Results 

Upgradient 317 FD West of 317 HC 

317422 317172 

Parameter BSE MSE FSE BSE MSE FSE 

DO (mg l-1) 2.24 -- -- 0.73 -- -­

NO3 (mg l-1) 0.163 -- -- 0.206 -- -­

Fe 2+ (mg l-1) <0.1 -- -- 0.5 -- -­

SO4 (mg l-1) 68.4 -- -- 94 -- --

Mn (mg l-1) 0.13 -- -- 0.053 -- -­

TOC (mg l-1) <5 -- -- <5 -- -­

ORP (mV) 7 -- 67 -68 -- -41 

S. Cond. (uS cm-1) 1200 -- 1600 1200 -- 1000 

pH 6.9 -- 6.4 7 -- 6.2 

Within and downgradient 317 FD 

317322 317332 317342 317432 

BSE MSE FSE BSE MSE FSE BSE MSE FSE BSE MSE FSE 

DO 0.90 0.67 0.61 1.8 2.8 1.7 0.57 0.75 0.95 0.52 5.9 0.64 

NO3 0.29 -- <1 -- -- <0.2 -- -- <0.2 0.588 -- <0.2 

Fe 2+ 3.2 -- 6.1 -- -- -- -- -- -- <0.1 -- <0.1 

SO4 16 -- 2.5 -- -- 55 -- -- 71 102 -- 90 

Mn 0.9 -- 0.32 -- -- -- -- -- -- 0.11 -- 0.1 

TOC 18 -- 41 -- -- 4 -- -- 3 <5 -- 2.1 

ORP -120 -- -410 -43 -18 -3 110 89 130 28 137 74 

S. Cond. 2100 2100 2100 1100 1300 1400 1100 1300 1300 1100 1300 1100 

pH 7 6.9 7.1 6.9 6.9 6.7 6.9 6.8 6.6 6.9 6.9 6.7 

Within 317 HC 

317151 317181 317221 317452 

BSE MSE FSE BSE MSE FSE BSE MSE FSE BSE MSE FSE 

DO 0.99 1.22 0.48 0.8 0.58 0.54 -- -- 0.46 0.73 -- 0.34 

NO3 0.0436 -- 1.6 -- -- <0.2 -- -- <0.2 0.298 -- -­

Fe 2+ <0.1 -- 0.2 -- -- -- -- -- -- -- -- -­

SO4 74.9 -- 81 -- -- 170 -- -- 120 80.8 -- --

Mn 0.093 -- 0.038 -- -- -- -- -- -- -- -- -­

TOC <5 -- 3.3 -- -- 3 -- -- 2.7 <5 -- -­

ORP 100 64 45 -0.9 -7 -21 -- -- -22 -52 -- -36 

S. Cond. 1100 1100 890 1300 1300 1300 -- -- 940 1100 -- 1000 

pH 6.9 6.9 6.5 7 6.9 6.5 -- -- 6.6 6.9 -- 6.8 

Upgradient and within 319 HC 

MW007 319171 319261 

BSE MSE FSE BSE MSE FSE BSE MSE FSE 

DO 0.51 -- 16.4 -- -- -- -- -- -­

NO3 <1 -- -- 0.647 -- 1.4 0.147 -- 0.35 

lvii 
Fe 2+ <0.1 -- -- <0.1 -- 4.8 <0.1 -- 2.1 

SO4 113 -- -- 129 -- 110 223 -- 130 

Mn 0.11 -- -- 0.046 -- 0.2 0.61 -- 0.16 

TOC <5 -- -- <5 -- 3.4 <5 -- 3.9 

ORP -150 -- 150 -- -- -- -- -- -­

S. Cond. 1100 -- 880 -- -- -- -- -- -­

pH 6.9 -- 6.9 -- -- -- -- -- -­

S Data not collected 

Table 4-10. Geochemical Indicator Traits 

Concentration Interpretation 

Analyte 

Dissolved Oxygen #1.0 mg l-1 If DO is greater than 1.0 mg l

-1 (aerobic conditions) reductive dechlorination unlikely; 

however, cometabolism and direct oxidation are possible. 

Nitrate <1 mg l-1 At higher concentrations, may compete with reductive pathway. Reductive 

dechlorination of PCE and TCE can occur under these mildly reducing conditions; 

direct oxidation is also possible. 

Soluble manganese (Mn2+) Increasing Increased concentrations of Mn2+ and Fe2+ coinciding with low DO levels are indicators 

and ferrous iron (Fe2+) concentrations that insoluble Mn4+ and Fe3+ are serving as electron acceptors. Reductive 

dechlorination of PCE and TCE possible under these mildly reducing conditions. 

Sulfate <20 mg l-1 At higher concentrations, may compete with reductive pathway; however, plumes with 

high sulfate levels can still support reductive dechlorination. Reductive dechlorination 

of DCE occurs under these stronger reducing conditions. 

TOC >20 mg l-1 Carbon/energy source, drives dechlorination 

Oxidation Reduct i on <100 mV Reductive dechlorination possible for highly chlorinated, electron poor compounds 

Potential (ORP) under mild reducing conditions (manganese, nitrate, iron); dechlorination of lesser 

chlorinated compounds requires stronger reducing conditions (sulfate, 

methanogenesis). 

Specific Conductance Above background Increase in ionic activity, possibly due to analyte degradation 

pH 5<pH<9 Optimal range for reductive pathway. 

lviii 
Figure 4-7. ORP Ranges for Various Biochemical Reducing Conditions 

• The influence of the planted system on ground water within this group of wells is uncertain. The conditions at 

each well were largely present at baseline and have not changed appreciably. 

Well 317322 is centrally located near the southern edge of the 317 FD. The concentration and trend of electron acceptors 

were within ranges normally associated with iron or possibly sulfate-reducing conditions. Conditions were strongly 

anaerobic at baseline and have become even more so during the study period possibly as a consequence of rhizospheric 

activity, which is expected to have such an effect. It is located in an area with some of the heaviest contamination, which 

may have helped initiate and promote anaerobic metabolism earlier than other areas. Concentrations for four of the five 

individual target analytes in samples collected from 317322 decreased over time, including TCA (99.6%), CLF (83%), 

TCE (52%) and DCA (36%). DCE increased sharply from 6.4 to 42 mg l-1; however, given the presence of strong 

reducing conditions capable of supporting dechlorination of DCE, it is suspected that the increased DCE is principally 

the result of transport from the surrounding soil matrix. 

317 HC. The monitoring wells within and upgradient of the 317 HC exhibit similar geochemical features. For the most 

part they are characterized by low DO (0.34 to 0.73 mg l-1), low nitrate (0.30 to <0.20 mg l-1), high sulfate concentrations 

(81 to 170 mg l-1), a moderately low ORP (45 to -41 mV), and similar specific conductance (890 to 1300 uS/cm). These 

indices suggest that the environment within this group of wells lies somewhere between nitrate- and iron-reducing 

conditions. However, the analyte data do not confirm this observation. VOC concentration increases were noted for each 

analyte over the course of the study period in 317181 and 317221. This includes TCE and TCA, which are normally 

susceptible to reductive dechlorination under nitrate and iron-reducing conditions. It may be that the absence of 

lix 
dechlorination is a reflection of the lack of TOC to participate in the redox reaction. Well 317151 displayed the opposite

performance, with sharp declines in all analytes including DCE (72%) and DCA (62%), compounds which typically require

much stronger reducing conditions. Localized dilution does not appear to play a role in the decreases since the water

level dropped by 1.2 ft (0.4 m) between the BSE and FSE. The location of the dechlorination process is not clear, but

it is possible that the degradation by products were formed near the southern edge of the 317 FD where strong reducing

conditions have been observed and transported downgradient to 317151. 

319 HC. Well MW007, upgradient of the 319 HC, switched from anaerobic to aerobic conditions during the course of the

demonstration, with an increase in DO (0.51 to >1.0 mg l

-1) and ORP (-150 to 150 mV). There was no change in the level

of total VOCs (0.019 mg l-1). Well 319171, within the 319 HC, exhibits a dual nature. An increase in NO3

-

suggests that

the environment is moving away from reducing conditions, while increased concentrations of Mn (0.046 to 0.2 mg l

-1) and

Fe2+ (<0.1 to 4.8 mg l-1) and a decreasing concentration of SO4

2- (130 to 110 mg l-1) are indicative of a reducing

environment. (DO data are not available for this monitoring location). The concentration of each detected target VOC

(TCE not detected) declined over time with a combined decrease of 32% (0.28 to 0.19 mg l-1). 

Product/Byproduct Ratios. Throughout the 317/319 study area decreasing ratios of parent compounds to daughter

byproducts offer other indications of where reductive dechlorination is occurring. Under reducing conditions compounds

such as TCE and TCA degrade more readily than their respective byproducts DCE and DCA, which results in decreasing

ratios of TCE/DCE and TCA/DCA. In several cases increases in DCE and DCA were accompanied by increases in TCE

and TCA. These movements are more likely the consequence of transport processes and not reductive dechlorination.

Table 4-11 summarizes the results across the study area where decreases in TCE and TCA have occurred. Consistent,

decreasing ratios are seen at locations were reducing conditions are suspected (317322 and 317342). Where conditions

are less apparent (317432, 317151, 319171), ratios are either unchanged or increasing. 

Biological Indicators. The geochemical information helps determine if conditions are suitable for biodegradation. 

Bacterial identification and quantification strengthens the interpretation of the geochemical data. 

Analysis of PLFA has been demonstrated useful in providing information on the amount and types of bacteria present

in a system and how they are reacting to environmental factors (White et al., 1997). Specifically, PLFA gives quantitative

insight into two main areas of microbial communities: viable biomass and community structure. Phospholipid fatty acids

are found in the membranes of all living cells, but decompose rapidly upon cell death through enzymatic hydrolysis. Thus,

measuring the total PLFA content provides a gauge of viable microbial biomass. Categorizing and quantifying the

different fatty acid species creates profiles that can be used to distinguish the community composition among different

samples.

PLFA results are summarized in Table 4-12. Overall, the lab reported that the concentration of biomass was much lower

than that found in soil, with a median concentration of 0.4 pmol PLFA ml-1 water versus 145 pmol PLFA g-1 soil. There

were notable differences among the fatty acid profiles in groundwater samples, although most contained moderately

diverse community structures (data not shown). In general, the lipid makeup of groundwater samples was more varied

and different than soil samples, even for water samples collected near soil bores. For example, the community structure

of well 317342 did not correspond to the community structure of the soil sample SB28; the same is true for 317332 and

SB16 and 317322 and SB26. These differences are expected to diminish over time as the plantations mature and exert

a dominant influence within the subsurface environment. 

Within the 317 HC, well 317322 showed a substantial increase (32%) in gram-negative monoenoic bacteria. These

bacteria are of particular interest due to their ability to use a wide range of carbon sources and adapt quickly to

environmental conditions. Biomarkers for obligate iron and sulfate-reducing anaerobic bacteria, absent at baseline, were

detected (1.9% of PLFA) in a sample collected during the FSE. The implication is that groundwater in the vicinity of

lx 
Table 4-11. Groundwater Product / Byproduct Ratios 

Within and below 317 FD 

317322 317342 317432 

Analytes BSE MSE FSE BSE MSE FSE BSE MSE FSE 

TCA/DCA 2.3 0.2 0.01 2.9 1.8 4.7 3.2 2.1 1.9 

TCE/DCE 0.7 0.4 0.05 0.3 0.3 0.4 N/C N/C N/C 

Within 317 HC 

317151

Analytes BSE MSE FSE

TCA/DCA 4.8 9.4 5.0

TCE/DCE 4.7 21.4 9.0

Within 319 HC 

319171 

Analytes BSE MSE FSE 

TCA/DCA 6.6 7.0 12 

TCE/DCE N/C N/C N/C N/C= Not calculable 

Table 4-12. Selected Groundwater PLFA Results 

% of Total PLFA pmol PLFA ml-1 

Well No. Monoenoic, Gram- Obligate Desulfobacter-like Actinomycetes Bacterial Biomass 

negative bacteria anaerobes: Iron sulfate reducers (obligate and

reducers and and facultative facultative

Desulfovibrio-like anaerobes: aerobes):

sulfate reducers 10me16:0 10me18:0

Baseline Final Baseline Final Baseline Final Baseline Final Baseline Final 

Upgradient, within, and downgradient of 317 FD

317322 46.0 60.7 0.0 1.9 1.8 1.2 0.1 0.0 18 7

317332 --- 40.2 --- 0.0 --- 6.4 --- 0.0 --- 0.4

317342 --- 69.8 --- 0.0 --- 1.2 --- 0.0 --- 0.4

317422 29.9 Lost 0.0 Lost 1.7 Lost 1.3 Lost 1 Lost

317432 43.0 24.8 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.3

Upgradient and within 317 HC

317151 Lost 42.7 Lost 0.0 Lost 3.1 Lost 0.0 Lost 0.4

317172 21.0 --- 0.0 --- 1.3 --- 1.2 --- 1 ---

317181 --- 48.2 --- 0.0 --- 3.4 --- 0.0 --- 0.2

317221 --- 87.6 --- 0.0 --- 0.0 --- 0.0 --- 0.6

317452 54.7 --- 0.0 --- 4.2 --- 0.0 --- 4 ---

Upgradient and within 319 HC

319171 43.0 78.8 0.0 0.4 3.5 0.1 2.0 0.1 4 107

319261 59.9 24.1 0.0 0.6 1.7 0.3 0.3 0.3 15 35

MW007 40.7 --- 0.0 --- 0.0 --- 0.0 --- 1 ---

Bold values under Final column represent increases of 50% or more over Baseline; bold values under Baseline column indicate sampling 

points were Final values declined 50% or more. 

– Data not collected 

lxi 
317322 is shifting in nature from aerobic to anaerobic. There was a decrease in the fatty acid indicator for the 

Desulfobacter-like sulfate reducing bacteria, which suggests that the Desulfobacterium sp. may not be primarily 

responsible for reductive dechlorination. The decrease in total biomass (18 to 7 pmol ml-1) is not unexpected since it is 

well known that anaerobic metabolism is generally less efficient and therefore produces less biomass than aerobic 

metabolism. These data corroborate the general perception that conditions at 317322 are strongly anaerobic and can 

support bacteria capable of dechlorinating all of the target VOCs. 

Within the 319 HC, well 319171 showed a substantial increase (83%) in gram-negative monoenoic bacteria. This was 

accompanied by an increase of more than 25-fold in total biomass (4 to 107 pmol ml-1). Given the relatively low level of 

available food as measured by TOC (3.4 mg l-1), the large build-up of bacteria and biomass suggest the presence of 

aerobic respiration since it is much more growth-efficient (capable of growing larger on a given measure of food) than 

anaerobic metabolism. However, the development of iron and sulfate-reducing anaerobic bacteria during the same period 

implies a trend toward anaerobiosis. Thus 319171 exhibits both aerobic and anaerobic traits, a conclusion in agreement 

with the trends of the geochemical data for this location. 

Soil. Geochemical data were used as indicators of the capability of the soil within the 317 FD to support a reducing 

environment. Data includes surveillance of terminal electron acceptors (manganese and iron) and available food sources 

(TOC). It is assumed that a portion of the manganese and iron are in insoluble forms (Mn4+ and Fe3+) and that anaerobic 

conditions will favor the bacterial reduction of these oxidized metals into more soluble (reduced) species(Mn2+ and Fe2+) 

with an accompanying decrease in the soil-bound concentration of total manganese and iron. The level of TOC is 

expected to increase in response to expression of root exudates and decaying root matter. 

The data are summarized in Figure 4–8, which is a simplified representation of the 317 FD and FDCP, and Table 4-13. 

Across the study area, there were measurable but insignificant changes in the concentration of iron and manganese. 

There was a large increase of nearly 8-fold in the average concentration of TOC (2,700 to 21,000 mg kg-1). Increases 

were observed at all sampling locations across the 317 FD and viewed initially as a natural response to root growth and 

influence permeating the soil volume. However, this interpretation is less certain since the (unplanted) 317 FDCP also 

exhibited a similar growth in TOC. 

It was noted earlier that the areas of heaviest contamination occur along the western and southern borders of the 317 

FD. Soil bores SB06, SB24, and SB26 lie along these borders. These locations exhibited decreases in manganese and 

iron and increases in TOC well above either the site-wide average or that observed in the 317 FDCP. It is suspected that 

these trends, which run counter to the trends of the other soil bore locations, have been induced by a shift in the 

subsurface environment toward anaerobiosis. Well 317322, which is located just west of SB26, was described previously 

as exhibiting geochemical and biological characteristics of strongly reducing conditions. These observations lend support 

for the association of anaerobic conditions and areas of elevated contamination within the 317 FD. 

Biological Indicators. PLFA results are summarized in Table 4-14. Overall, the mean concentration of biomass and 

monoenoic gram-negative bacteria exhibited no significant changes. During the course of the study, the lipid make of 

soil samples varied less as the community structures of some locations changed to resemble other locations. For 

example, samples SB14, SB16 and SB28 changed to resemble SB22; and SB02 and SB08 changed to resemble SB20. 

In general, the PLFA profiles among soil samples varied less than water samples. This convergence of biomarkers is 

seen as an indication that the root system is encouraging the development of similar microbial communities. 

Obligate anaerobic, iron and sulfate-reducing bacteria were absent from all samples collected at baseline. This was an 

expected consequence of planting activities. Boreholes were drilled to depths of 10 ft (3 m) bgs at 200 locations across 

the 317 FD. This likely resulted in localized aeration of the soil volume, perhaps including, perhaps, the 317 FDCP, which 

is located 15 ft (4 m) north of the 317 FD. Obligate anaerobes were detected in all samples collected at the end of the 

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Figure 4-8. Mean Soil Geochemical Results 

Control Plot 

SB#29 SB#30 SB#31 Results in mg kg-1, except pH. 

BSE FSE – Data not collected 

Fe --- -- 17,000 25,000 --- --

Mn --- -- 440 550 --- --

TOC --- -- 2,400 16,000 --- --

pH --- -- 7.5 7.9 --- --

317 Area French Drain 

SB#01 SB#02 SB#03 SB#04 SB#05 

BSE FSE BSE FSE 

Fe --- --- 15,000 32,000 --- — 19,000 17,000 --- ---

Mn --- — 280 450 --- --- 500 320 --- — 

TOC --- --- 5,200 26,000 --- — 3,200 24,000 --- ---

pH --- — 7.6 8.1 --- --- 7.8 8.6 --- — 

SB#06 SB#07 SB#08 SB#09 SB#10 

BSE FSE BSE FSE BSE FSE 

Fe 22,000 14,000 --- --- 27,000 44,000 --- — 15,000 19,000 

Mn 710 480 --- --- 390 550 --- — 430 350 

TOC <90 30,000 --- --- 3,400 23,000 --- — 2,200 22,000 

pH 7.6 8.6 --- --- 7.6 7.8 --- — 7.7 8.2 

SB#11 SB#12 SB#13 SB#14 SB#15 SB#16 

BSE FSE BSE FSE BSE FSE 

Fe --- --- 20,000 26,000 --- — 25,000 31,000 --- --- 19,000 17,000 

Mn --- — 360 420 --- --- 420 450 --- — 340 340 

TOC --- --- 2,900 21,000 --- — 4,100 26,000 --- --- 1,500 24,000 

pH --- — 7.8 8.3 --- --- 7.6 7.9 --- — 8.0 8.6 

SB#17 SB#18 SB#19 SB#20 SB#21 SB#22 

BSE FSE BSE FSE BSE FSE 

Fe --- — 16,000 16,000 --- --- 28,000 32,000 --- — 16,000 27,000 

Mn --- — 380 270 --- --- 460 480 --- — 660 430 

TOC --- — 1,800 15,000 --- --- 3,600 17,000 --- — 5,200 8,600 

pH --- — 7.7 8.3 --- --- 7.5 7.7 --- — 7.8 8.2 

SB#23 SB#24 SB#25 SB#26 SB#27 SB#28 

BSE FSE BSE FSE BSE FSE 

Iron --- --- 24,000 17,000 --- — 21,000 20,000 --- --- 15,000 19,000 

Mn --- — 410 310 --- --- 380 350 --- — 330 370 

TOC --- --- 1,800 29,000 --- — <90 17,000 --- --- 3,000 21,000 

pH --- — 7.5 8.2 --- --- 7.1 7.8 --- — 7.9 8.1 

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Table 4-13. Summary of Soil Geochemical Data 

Analyte Mean BSE Range Mean FSE Range 

BSE FSE 

Fe 20,000 15,000 - 28,000 24,000 14,000 - 44,000 

Mn 430 280 - 710 410 270 - 550 

TOC 2,700 <90 - 5,300 21,000 8,600 - 30,000 

pH 7.6 7.1 - 8.6 8.2 7.7 - 8.6 

Table 4-14. Summary of Soil PLFA Results 

% of Total PLFA pmol PLFA g-1 

Monoenoic, Gramnegative bacteria Obligate 

anaerobes: Iron 

reducers and 

Desulfovibrio-like 

sulfate reducers 

Desulfobacter-like 

sulfate reducers 

and facultative 

anaerobes: 

10me16:0 

Actinomycetes 

(obligate and 

facultative 

aerobes): 

10me18:0 

Bacterial Biomass 

Baseline Final Baseline Final Baseline Final Baseline Final Baseline Final 

SB02 22.8 30.9 0.0 3.5 11.9 3.1 1.4 0.7 176 1,298 

SB04 27.9 22.2 0.0 2.4 12.5 12.3 2.7 0.9 519 76 

SB06 35.5 30.3 0.0 4.1 2.5 8.4 1.4 1.3 229 185 

SB08 41.5 23.8 0.0 2.8 7.0 2.7 2.1 0.7 1,069 375 

SB10 36.6 22.0 0.0 1.6 10.3 10.8 4.6 1.0 296 128 

SB12 23.2 19.9 0.0 4.2 7.1 5.4 2.0 2.0 299 1,011 

SB14 18.0 26.1 0.0 1.9 1.7 2.5 0.3 0.4 215 322 

SB16 25.3 24.0 0.0 2.3 6.6 7.9 1.8 0.8 184 96 

SB18 24.4 23.0 0.0 4.3 7.3 14.0 2.1 1.4 189 108 

SB20 25.2 19.1 0.0 3.0 7.9 2.4 1.9 0.5 233 382 

SB22 21.6 30.4 0.0 4.1 5.6 4.6 1.0 0.7 106 145 

SB24 17.4 25.0 0.0 5.5 2.4 6.8 0.1 0.3 230 137 

SB26 15.3 14.6 0.0 2.8 2.9 4.6 1.7 1.1 180 105 

SB28 27.3 24.2 0.0 7.8 5.6 5.1 2.5 1.1 103 113 

SB30 35.7 25.7 0.0 3.2 7.0 3.8 2.8 0.7 613 879 

Average 26.5 24.1 0.0 3.6 6.5 6.3 1.9 0.9 309 357 

study period. While, perhaps, not a direct reflection of the action of the trees (these anaerobes were detected in the 

control plot as well), it does suggest that available oxygen is being used up by biotic and/or abiotic processes. 

4.4.2.3 Modeling and Confirming Water Use and Hydraulic Control 

Continuous groundwater elevations were evaluated over the period covering November 1999 through December 2001. 

Its analysis informs on important aspects of the site’s hydrogeology and the affect of the young plantation on water levels. 

A clear response to precipitation was observed, with hydraulic heads rising within one hour of the onset of precipitation. 

The magnitude of the water level response is roughly correlated with the amount of rainfall, though smaller wintertime 

precipitation events may create significant head increases because of concurrent snowmelt. 

Additional examination of the continuous head data reveals additional details about the effect of the phytotechnology 

system on the nearby water levels. The 809 trees, including more than 500 TreeWells® targeting a confined aquifer, were 

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planted in summer 1999. The TreeWells® were planted deep (“up to their shoulders”) in order to maximize their initial 

root depth within their lined boreholes, and they were pruned heavily in order to reduce stress during their hot-weather 

planting. In 2000, the growing season was cool. The height of the growing season (June - August) registered only 570 

CDD as compared to an average of 628 CDD for the area, and 32<C (90<F) was not reached until September (data not 

shown). During that summer, the trees did not exhibit significant above ground growth; instead, the cool weather seemed 

to give them time to establish themselves. The data from the cool 2000 growing season shows no obvious impact of the 

trees on water levels. However, in September 2000, during a brief warming period, the plantation began exhibiting diurnal 

fluctuations (data not shown). These fluctuations, which are up to 7 cm (0.25 ft) in well 317151, were present to a lesser 

degree at 317172, 317452, and 317181. Diurnal fluctuations were not present at 317391, which is upgradient of the 

phytotechnology system, or at the two 319 Area wells 319261 or 319171. The water levels in the 319 Area wells may 

not be responding due to different hydrologic conditions or a smaller plantation. 

The diurnal fluctuations continued during the 2001 growing season and varied in amplitude with the amount of daily solar 

radiation. What is noteworthy of the 2001 data is that the water levels, such as in well 317151, exhibit a gradual 

downward trend during days of high sunlight and strong diurnal fluctuations, with gradual recovery of water level during 

cloudy days that lack strong fluctuations (Figure 4-9). For this young plantation, this is an early indication of what is 

expected in the upcoming years, namely that the maturing poplars will exert an increasing effect on the site’s hydrology 

and ultimately result in hydraulic containment. This anticipated containment has been evaluated through groundwater 

modeling that incorporated the best estimate of water use by the TreeWells® through each month (Quinn et al. 2001). 

Results suggest that despite leaf-off winter periods, the plantation will provide full containment on the larger western (317 

Area) side of the plantation, and a strong degree of containment on the eastern (319 Area) side. 

4.4.2.4 Health and Growth of the Planted System 

During their first year from planting, the trees developed, although at a slower rate than their potential, and successfully 

established themselves at the site, both at the source area and at the hydraulic control areas. While some of the initial 

trees had to be replanted, as they did not survive the transplant shock (the trees were planted in an extremely hot and 

dry weather), the health of those that overcame the transplant (the majority) was more than satisfactory. It is believed 

that the non-optimal climatic conditions at the time of transplant and throughout the first summer caused the trees to go 

into a “survival” mode (rather than a fast growth mode), and that a cooler than expected growing season of 2000 slowed 

down the trees’ growth compared to their potential. 

The 2001 growing season was overall was more favorable to plant growth than the 2000 season. In the summer of 2001, 

a number of the poplars started to show the large apical leaves that are a sign of unrestricted water availability. Poplars 

grew and average of 10 mm in diameter and 109 cm in height. Poplars grew 2.8 more times in height and 1.6 times more 

in diameter in 2001 compared to 2000. On average, during the 2001 summer, willows increased 7 mm in diameter and 

20 cm in height. Compared to the year 2000 growing season, willows grew 2.6 times more in height, while growing at 

about the same pace in diameter (in 2000 the willows grew substantially more in diameter than in height). 

The groundcover species sowed at the site grew according to expectations and were able, by the summer of 2000, to 

establish themselves as a ground cover and minimize risks of erosion and runoff. In some areas, local vegetation 

composes a significant portion of the final plant cover, without decreasing the groundcover effectiveness. 

4.5 Discussion 

The phytotechnologies deployed at ANL-E sites are supplementary to and intended to eventually replace an existing 

pump-and-treat system. As the trees completed their third growing season in the field (2001), a significant amount of 

information had been collected to assess their performance at achieving the remedial objectives. From this data, the 

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Figure 4-9. Well 317151 Water Levels, July 1-5, 2001 

young plantations appear to have begun to influence the cleanup area. The deep-planted trees have tapped into the 

lower saturated zone and are consuming contaminated water. Degradation of volatile organics from the source area soil 

is occurring in the plants, and the rhizosphere is moving toward conditions that are capable of supporting reductive 

dechlorination. In ground water, pollutants are being removed (tritium) or degraded (VOCs) in some areas of the 

contaminated groundwater plumes. Overall, less contamination is reaching the extraction well system than before the 

plants were installed. 

Probably the key remediation mechanism of this planted system is the interception and removal of water from the 

impacted aquifer (i.e. phytostabilization). Consequently, the magnitude of transpiration is one of the most important 

monitoring parameters: transpiration rates for the trees at the site provide information for evaluating current water 

removal as well as predicting future water usage. Quantified sapflow rates were used to estimate transpiration. Data 

show that maximum sapflow rates determined during the 2001 growing season are still below the plants’ potential as 

estimated by the hydraulic flux at baseline. However, the year-to-year increase in rates suggests that across the plantation 

water use is closing the gap. These data complement others derived from the recording of continuous groundwater 

elevation at the site, which shows diurnal fluctuations of hydraulic heads in correspondence with elevated daily solar 

radiation (transpiration) during the vegetative season. 

Multiple lines of evidence are often needed to demonstrate biodegradation processes at contaminated sites (EPA, 1998). 

The lines of evidence used to examine biodegradation for this project include (1) detection of TCE and its degradation 

products in tree tissue in the 317 FD; (2) groundwater chemical data that indicate decreasing concentrations of target 

VOCs and increasing concentrations of degradation byproducts (3) geochemical data that indicate depletion of electron 

lxvi 
donors and acceptors; and (4) laboratory microbiological data that indicate the bacteria present at a site can degrade 

contaminants. 

Tissue analysis of willows growing at the contaminated source area indicate that TCE and PCE are taken up by the trees 

in measurable amounts, and that at least a portion of the transported contaminants is degraded in the leaf. The 

intermediate degradation product, TCAA, appears to be subsequently degraded further in the leaf litter to background 

levels. 

TCE and TCA and their degradation byproducts are seen at nearly all groundwater wells throughout the study area, 

implying that microbial attenuation of some form has occurred. In a number of cases monitoring data are unclear about 

where or how degradation byproducts were formed, and at other locations VOC, geochemical, and biological indicators 

suggest that reductive dechlorination is ongoing. 

Source area soils, which may have been aerated as a result of plant installation, have lost much of their initial aerobic 

nature. Obligate-anaerobic, iron and sulfate-reducing bacteria have established colonies across the 317 FD, and there 

appears to be a particularly strong anaerobic character building in segments of the source area where contaminant levels 

are greatest. 

After enduring a transplant shock and below-optimal growth conditions during the first two years in the field, the trees 

grew at faster rates in 2001. Their increased size is reflected in increased transpiration rates, and presumably 

larger/longer root systems and enhanced rhizosphere to better influence contaminant reduction and hydraulic control. 

Modeling based on data collected during the first three years of the project predicts full containment of the 317 plume, 

and significant containment of the 319 plume. 

Phytotechnologies are by definition dependant on weather and are equally difficult to predict specifically. The timing 

of tree growth is as variable as sunshine and cloud patterns, but equally reliable on the average in the long term. For 

a variety of reasons these planting did not develop as quickly as expected. The question of when trees will be 

effective is not answered in this demonstration, and that uncertainty must be built into regulatory acceptance and 

financial considerations of similar applications. 

4.6 Data Quality Summary 

A review of the primary sample data and associated QC analyses was performed to determine whether the data 

collected were of adequate quality to provide proper evaluation of the project’s technical objectives. Three primary 

parameters were validated: 

1. TCE in soil 

2. Target VOCs in ground water (see section 4.3.1.2 for a list of target VOCs) 

3. Tritium in ground water 

The results of the measurements designed to assess the data quality objectives are summarized below. A detailed 

description of project quality assurance can be found in the companion Technology Evaluation Report for this project. 

lxvii 
4.6.1 TCE in Soil 

Accuracy objectives for soil TCE were assessed by the evaluation of 5 spiked samples analyzed in accordance with 

standard procedures in the same manner as the samples. Recovery values for TCE were well within objectives specified 

in the project Quality Assurance Project Plan. 

Recovery for trichloroethylene averaged 97.2% and for tetrachloroethene (non-primary) the average recovery was 97.5%, 

giving an overall percent recovery of 97.4% for the critical organics. 

Precision was assessed through the analysis of 5 duplicate spikes. Data quality objectives for precision, established as 

RPD values less than 25% , were met. 

Detection limits were established so as to be sufficiently below the concentration of interest for TCE. The program 

required detection limit was established at 50 ppb. Due to the laboratory sample preparation of field methanol extracted 

samples, this required a method detection limit (MDL) of 1 ppb. The MDL was successfully achieved. 

Comparability was achieved through the use of a QAPP, approved EPA protocols, and verified by the validation of 

analytical data, which indicated that the QAPP and method-specified criteria were met. 

Completeness The number of samples for the baseline analysis required to meet completeness was estimated to be 84 

samples. Eighty-four samples were collected in the field and successfully analyzed by the laboratory during both the 

baseline and final sampling events. 

Representativeness refers to the degree with which a sample exhibits average properties of the waste stream at the 

particular time being evaluated. For soil samples, this is assessed in part, by the analysis of split samples spiked in the 

field with trichloroethene, which also provide insight into the homogeneity, or heterogeneity, of the matrix. Spiked split 

samples have, inherent in the result, combined field and analytical variability. The spiked split samples indicated 

reasonable agreement in results, with RPD values for the baseline spiked duplicates averaging 18.3 % with a maximum 

of 38.4 %, final spiked duplicates averaged 19.7 % with a maximum of 50 %, and a goal of #35 % RPD. 

4.6.2 Target VOCs in Ground water 

Accuracy objectives for groundwater target VOCs were assessed by the evaluation of 5 spiked samples during the 

baseline sampling event, 2 spiked samples during the midterm sampling event, and 6 spiked samples during the final 

sampling event. The spiked samples were analyzed in accordance with standard procedures in the same manner as the 

samples. Recovery values for the critical compounds were well within objectives specified in the QAPP, except for one 

cis-1,2-dichlorethene result during the baseline sampling event, and one sample during the final event. The sample 

during the final event with high % R (up to 135 %) had sample concentrations up to 79 % of the spike concentration. The 

highest spike recovery on other samples during the final event was 118%. (The QAPP actually required that the % R 

be achieved only for trichloroethene.) Overall recovery averaged 104 % for the target VOCs. 

Precision was assessed through the analysis of 5 spiked duplicates during the baseline sampling event, 2 spiked 

duplicates during the midterm sampling event, and 6 spiked duplicates during the final sampling event. Data quality 

objectives for precision, established as RPD values less than 20 %, were met. 

Detection limits achievable by the laboratory method were sufficiently below the concentration of interest for the 

groundwater target VOCs. The program therefore utilized the pre-established detection limit of 1 ppb. 

lxviii 
Comparability was achieved through the use of a QAPP, approved EPA protocols, and verified by the validation of 

analytical data, which indicated that the QAPP and method-specified criteria were met. 

Completeness The number of samples for the baseline analysis required to meet completeness was estimated to be 47 

results per volatile organic. Forty-eight baseline samples were collected in the field and analyzed by the laboratory. 

These samples were collected from eight wells at a rate of one per day for six days. During data validation, one sample 

was qualified as “R”, rejected do not use for any reason, leaving 47 valid analyses. Well 317452 had “less than” results 

for all analyses on all days, this well was not sampled as a “primary” well during the final sampling event. Forty-two 

samples (seven wells at one sample per well per six days) were collected in the field and analyzed by the laboratory. 

Representativeness refers to the degree with which a sample exhibits average properties of the waste stream at the 

particular time being evaluated. This is assessed in part by the analysis of field triplicates (duplicates are frequently 

utilized), which also provide insight into the homogeneity, or heterogeneity, of the matrix. Field triplicate samples have, 

inherent in the result, combined field and analytical variability. Results for calculating RSDs are used only when sample 

and triplicate results are all at least 2 times the MDL for a given target VOC. The triplicates indicated reasonable 

agreement in results, with RSD values for the triplicates averaging 5.4 % with a goal of #20 % RSD. 

4.6.3 Tritium in Ground Water 

Accuracy objectives for tritium were assessed by the evaluation of 1 spiked sample during the baseline sampling event, 

2 spiked samples during the midterm sampling event, and 2 spiked samples during the final sampling event. The spiked 

samples were analyzed in accordance with standard procedures in the same manner as the samples. Recovery values 

for tritium were well within objectives specified in the QAPP. Overall recovery averaged 103 % for tritium. 

Precision was assessed through the analysis of 1 sample duplicate during the baseline sampling event, 2 sample 

duplicates during the midterm sampling event, and 1 sample duplicate during the final sampling event. Results for 

calculating RPDs are used only when both the sample and duplicate result are all at least 2 times the MDL. Data quality 

objectives for precision, established as RPD values less than 15 %, were met. 

Detection limits achievable by the laboratory method were 500 pCi/L for tritium. This concentration is sufficiently below 

the concentration of interest; therefore, the project utilized the laboratory pre-established detection limit. 

Comparability was achieved through the use of a QAPP, approved EPA protocols, and verified by the validation of 

analytical data, which indicated that the QAPP and method-specified criteria were met. 

Completeness The number of samples for the baseline analysis required to meet completeness was unable to be 

statistically determined due to the minimal (two) number of analyses previously collected. The intent of the project (and 

QAPP) was to collect samples over six days from three different wells within the tritium plume, yielding 18 samples. Due 

to field conditions and placement of the wells, only two wells were available for sampling within the suspected tritium 

plume. Each of the two wells were sampled over six days for a total of 12 samples during both the baseline and final 

sampling events. 

Representativeness refers to the degree with which a sample exhibits average properties of the waste stream, at the 

particular time being evaluated. This is assessed in part by the analysis of field triplicates (duplicates are frequently 

utilized), which also provide insight into the homogeneity, or heterogeneity, of the matrix. Field triplicate samples have, 

inherent in the result, combined field and analytical variability. For tritium, the primary sample, duplicate, and triplicate 

were collected immediately after each other. Results for calculating RSDs are used only when sample and triplicate 

results are all at least 2 times the MDL. The field triplicates indicated reasonable agreement in results, with RSD values 

for the field triplicates averaging 4.4 % with a goal of #15 % RSD. A sample duplicate was collected during the midterm 

sampling event. 

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SECTION 5

OTHER TECHNOLOGY REQUIREMENTS

5.1 Environmental Regulation Requirements 

The deployment of phytotechnology at ANL-E is being conducted under the jurisdiction of the IEPA. Similar 

phytotechnology efforts conducted outside of the state of Illinois will likely be subject to alternate federal, state and/or local 

regulations consistent with the change in jurisdiction. Governing agencies may require permits prior to implementing a 

phytotechnology system of a similar size and purpose. Section 2 of this report further discusses the environmental 

regulations that may apply to this or similar phytotechnology applications. 

5.2 Personnel Issues 

The number of personnel required to implement a particular phytosystem is largely dependent on the size of the area 

to be treated. Large sites requiring extensive site preparation, tree planting, and other support items may require several 

individuals (inclusive of contractors), especially if there are constraints on time. The size of the 317/319 area at ANL-E 

covers approximately 2 hectares (5 acres) of which about 11,000 m2

 (120,000 ft2) consists of the tree plantings. 

During1999, the year in which the site preparation and tree installation took place, ANL-E utilized three full-time personnel 

in addition to contracted services. Estimated labor requirements for the ANL-E site are discussed in Section 3 of this 

report. 

For complex sites, there may be a need for specialized engineering and/or scientific services. For example, at the ANL-E 

site the physical effects of the tree plantings on the groundwater was modeled using the specialized hydrologic software 

program MODFLOW. Also, there was a need for generating engineering specifications, drawings, and installation details 

so that the state regulatory agency could review the system design. Radiological sites, such as the 317/319 Area, further 

require specialized training for personnel. Also, health physicists were routinely required to monitor activities and scan 

vehicles, samples, and equipment prior to leaving the site. 

The site owner, or other responsible party desiring the installation of a phytotechnology system may need to out source 

certain tasks. Potential out sourcing may involve a landscaping, construction firm, or well drilling firm equipped to perform 

the work. For example, the hybrid poplars used at ANL-E were initially grown at a tree farm owned by ANS. The hybrid 

poplars were grown and nurtured for about two years at that company’s nursery and were then shipped to ANL-E and 

planted using the TreeWell® system patented by ANS. 

Sampling events also require the services of several personnel, whether acquired in house or contracted. During the 

demonstration soil sampling events at ANL-E, a two-person Geoprobe® crew and a geologist were required to collect soil 

samples. Groundwater sampling additionally required one or two 2-person crews to sample selected wells and prepare 

those samples for off-site shipment. 

lxx 
Personnel present during sample collection activities at a CERCLA or RCRA waste site must have current OSHA health 

and safety certification and annual medical surveillance. 

Certain sites may require training above and beyond OSHA certification. For instance, the ANL-E site required all 

contractor personnel to attend a contractor orientation class and complete a Radiological Worker 1 training course. 

For most sites, the personnel protective equipment (PPE) for workers will include steel-toed shoes or boots, safety 

glasses, hard hats, and chemical resistant gloves. Depending on contaminant types, additional PPE (such as 

respirators) may be required. Noise levels would usually not be a concern for a phytotechnology technology. However 

some equipment used for vegetative clearing and regrading (e.g., mowers, chain saws, etc.), tree planting (e.g., trenching 

or drilling equipment) and maintenance activities (e.g., mowers and loaders for moving and spreading fertilizer) could 

create appreciable noise during short time periods. Thus, noise levels should be monitored for such equipment to ensure 

that workers are not exposed to noise levels above the time weighted average of 85 db over an 8-hr day. If this level is 

exceeded and cannot be reduced, workers would be required to wear hearing protection. 

5.3 Community Acceptance 

Phytotechnology approaches have received higher public acceptance than most conventional remedial options. Because 

phytotechnology is a solar-energy driven, passive technique, there are few environmental disturbances associated with 

the process. Phytotechnology systems are low maintenance and produce virtually no process residuals. They can be 

used along with, or in some cases, in place of intrusive mechanical cleanup methods. No appreciable noise beyond that 

generated by the short term use of installation equipment is anticipated for the majority of the treatment time. A fence 

may be desirable to keep unauthorized visitors from entering the site. 

Potential hazards to a surrounding community may include exposure to particulate matter that becomes airborne during 

drilling or trenching operations used to plant rows of trees. Air emissions of VOCs are possible if volatile contaminants, 

such as TCE, are present in the soil (as was the case at ANL-E). Particulate air emissions from installation activities can 

be controlled by dust suppression measures. 

lxxi 
SECTION 6

TECHNOLOGY STATUS

6.1 Previous Experience 

Continued research is needed to better understand the advantages and limitations of the phytoremediation, particularly 

in the area of contaminant transport. A number of studies have been conducted to determine if organic contaminants 

simply pass through the trees and are released to the atmosphere via leaf stomata during evapotranspiration. Research 

in this area has produced mixed results and is not close to quantifying the amounts of organics released. Although 

rhizopheric biodegradation and breakdown of chemicals through metabolic activities within plant tissue are components 

of phytoremediation, these processes as they relate to this technology are not well understood. 

While most phytoremediation systems are limited to the upper three meters of the soil column, new methods may be 

effective to greater depths. Researchers and companies that offer phytoremediation services have developed and 

employed specialized (often proprietary) techniques that train the tree roots to penetrate to greater depths or herd them 

into deeper contamination zones via subsurface drip irrigation. 

ANS reports on their web site (www.treemediation.com) to have project sites including government and commercial 

operations affected by landfills, sludge lagoons and spills. ANS also claims to have the distinction of being the first 

company to obtain regulatory approval for groundwater phyto-projects in the states of New York, New Jersey, Michigan, 

Maryland, Wisconsin, Illinois, North Carolina, Louisiana and Ohio. 

6.2 Ability to Scale Up 

Phytoremediation has been described as being well suited for use at very large field sites, where other methods of 

remediation are not cost effective or practical (EPA, 2001). The type of phytoremediation system that was installed at 

ANL-E is an evolving and adaptive process that can be adjusted to different sized sites having various site conditions. 

That particular system involves treatment of VOCs and tritium in groundwater in the uppermost aquifer, having a depth 

to top of unit ranging from 6.7 m -10.4 m ( 22 ft - 34 ft) bgs. 

ANS has reported additional projects in which the impact of TreeMediation® is being evaluated on soil as deep as 6 m 

(20 ft) and groundwater up to 15 m (50 ft) bgs for the cleanup of organic compounds, primarily VOCs (TCE, PCE & 

BTEX), and inorganic compounds, including heavy metals. With regards to non-volatile organics, ANS has reported that 

soils contaminated with pesticides (Alachlor and Atrazine, and other agricultural compounds) and petroleum hydrocarbons 

have been successfully treated. 

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lxxiii