United States 

Environmental Protection 

Agency 

Surfactant-Enhanced Extraction 

Technology Evaluation 

EPA - BMBF Bilateral Site 

Demonstration 

Versuchseinrichtung zur 

Grundwasser-und 

Altlastensanierung (VEGAS) Facility 

Stuttgart, Germany 

Innovative Technology 

Evaluation Report
September 2000 

SURFACTANT-ENHANCED 

EXTRACTION TECHNOLOGY 

EVALUATION

EPA - BMBF BILATERAL SITE 

DEMONSTRATION

Versuchseinrichtung zur Grundwasser-und 

Altlastensanierung (VEGAS) Facility 

STUTTGART, GERMANY

INNOVATIVE TECHNOLOGY EVALUATION REPORT 

By

Tetra Tech EM Inc. 

1230 Columbia Street, Suite 1000 

San Diego, California 92101 

Contract No. 68-C5-0037 

Work Assignment No. 0-05 

Work Assignment Manager 

Ann Vega 

Land Remediation and Pollution Control Division 

National Risk Management Research Laboratory

 Cincinnati, Ohio 45268 

National Risk Management Research Laboratory 

Office of Research and Development 

U.S. Environmental Protection Agency

 Cincinnati, Ohio 45268 

EPA/540/R-07/004
 NOTICE 

The information in this document has been prepared for the U.S. Environmental Protection Agency’s (EPA’s) 

Superfund Innovative Technology Evaluation program by Tetra Tech EM Inc. under Contract No. 68-C5­

0037. This document has been prepared in support of a bilateral agreement between the EPA and the 

Federal Republic of Germany Ministry for Research and Technology. This document has been subject to 

the EPA’s peer and administrative reviews and has been approved for publication as an EPA document. 

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

for use. 

ii 
FOREWORD 

The U.S. Environmental Protection Agency (EPA) 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 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 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 groundwater; 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 has 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. 

Hugh W. McKinnon, Director 

National Risk Management Research Laboratory 

iii 
CONTENTS 

NOTICE........................................................................................................................................................i i 

FOREWORD ...............................................................................................................................................iii 

ACRONYMS AND ABBREVIATIONS ................................................................................................... vii 

CONVERSION TABLE............................................................................................................................viii 

ACKNOWLEDGMENTS ...........................................................................................................................ix

EXECUTIVE SUMMARY..................................................................................................................... ES-1 

1.0 INTRODUCTION ........................................................................................................................... 1 

1.1 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION PROGRAM................ 3 

1.2 BILATERAL AGREEMENT BETWEEN THE UNITED STATES AND 

GERMANY ON REMEDIATION OF HAZARDOUS WASTE SITES........................... 5 

1.3 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY DESCRIPTION.......... 6 

1.4 KEY CONTACTS .............................................................................................................. 8

2.0 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY EFFECTIVENESS................ 10 

2.1 DEMONSTRATION BACKGROUND ........................................................................... 10 

2.1.1 VEGAS Research Facility ................................................................................... 10 

2.1.2 Preparation of the Artificial Aquifer.................................................................... 12 

2.1.3 Process Description and Planned Operation ........................................................ 12 

2.1.4 Demonstration Objectives and Approach ............................................................ 17 

2.2 DEMONSTRATION PROCEDURES ............................................................................. 20 

2.2.1 Sampling and Analysis Program.......................................................................... 20 

2.2.1.1 Sampling and Measurement Locations................................................... 20 

2.2.2 Sampling and Analytical Methods....................................................................... 22 

2.2.3 Quality Assurance and Quality Control Program ................................................ 23 

2.2.4 Chronology of Process Operations and Changes to the Sampling Program........ 23 

2.3 DEMONSTRATION RESULTS AND CONCLUSIONS ............................................... 26 

2.3.1 Results and Discussion ........................................................................................ 26 

2.3.1.1 Primary Objective P-1 ............................................................................ 26 

2.3.1.2 Primary Objective P-2 ............................................................................ 27 

2.3.1.3 Secondary Objective S-1 ........................................................................ 31 

2.3.1.4 Secondary Objective S-2 ........................................................................ 34 

2.3.1.5 Secondary Objective S-3 ........................................................................ 39 

2.3.1.6 Secondary Objective S-4 ........................................................................ 39 

iv 
CONTENTS (Continued)

 2.3.2 Data Quality......................................................................................................... 41

 2.3.3 Conclusions.......................................................................................................... 45 

3.0 ECONOMIC ANALYSIS ............................................................................................................. 46 

4.0 TECHNOLOGY APPLICATIONS ANALYSIS .......................................................................... 47 

4.1 FEASIBILITY STUDY EVALUATION CRITERIA...................................................... 47 

4.1.1 Overall Protection of Human Health and the Environment................................. 47 

4.1.2 Compliance with ARARs .................................................................................... 47 

4.1.3 Long-Term Effectiveness and Permanence ......................................................... 48 

4.1.4 Reduction of Toxicity, Mobility, or Volume Through Treatment....................... 48

 4.1.5 Short-Term Effectiveness .................................................................................... 48 

4.1.6 Implementability.................................................................................................. 48 

4.1.7 Cost ................................................................................................................ 49 

4.1.8 State Acceptance.................................................................................................. 49 

4.1.9 Community Acceptance....................................................................................... 49 

4.2 APPLICABLE WASTES ................................................................................................. 49 

4.3 LIMITATIONS OF THE TECHNOLOGY...................................................................... 49 

5.0 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY STATUS ............................... 50 

6.0 REFERENCES .............................................................................................................................. 51 

v 
FIGURES

1 LOCATION OF VEGAS RESEARCH FACILITY........................................................................ 2 

2 PROJECT ORGANIZATION ......................................................................................................... 7 

3 CROSS-SECTION OF ARTIFICIAL AQUIFER ......................................................................... 11 

4 MONITORING WELL CONFIGURATION................................................................................ 13 

5 SURFACTANT INJECTION/EXTRACTION SYSTEM............................................................. 14 

6 SURFACTANT RECOVERY SYSTEM ...................................................................................... 16 

7 CONCEPTUAL PLOT OF ANTICIPATED XYLENE MASS REMOVAL RATES.................. 18 

8 SAMPLING AND MONITORING LOCATIONS ....................................................................... 21 

9 XYLENE MASS REMOVAL RATES DURING THE DEMONSTRATION............................. 30 

TABLES 

1 CRITICAL MEASUREMENT PARAMETERS .......................................................................... 17 

2 NONCRITICAL MEASUREMENT PARAMETERS.................................................................. 19 

3 ANALYTICAL METHODS: SURFACTANT-ENHANCED EXTRACTION SYSTEM ........... 23

4 XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER 

(SAMPLING LOCATION S4, MONITORING LOCATION M1) .............................................. 27 

5 XYLENE CONCENTRATIONS IN THE EFFLUENT GROUNDWATER 

(SAMPLING LOCATION S2)...................................................................................................... 32 

6 ACUTE TOXICITY OF GROUNDWATER EFFLUENT TO DAPHNIA.................................. 34 

7 SUMMARY OF THE PROCESS FLOW RESULTS ................................................................... 35 

8 SELECTED PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE 

INFLUENT GROUNDWATER.................................................................................................... 36 

9 SURFACTANT CONCENTRATIONS OF GROUNDWATER EFFLUENT 

(SAMPLING LOCATION S2)...................................................................................................... 40 

10 RESULTS FOR MATRIX SPIKE QC SAMPLES ....................................................................... 42 

vi 
ACRONYMS AND ABBREVIATIONS 

ARARs Applicable or relevant and appropriate requirements 

ArGe Arbeitgemeinschaft (focon Probiotec) 

ASTM American Society for Testing and Materials 

ATTIC Alternative Treatment Technology Information Center 

BASF BASF AG 

BMBF Federal Republic of German Ministry for Research and Technology 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

CERI Center for Environmental Research Information 

CLU-IN Clean-up Information (on-line database) 

cm Centimeters 

oC Degrees Celsius 

€ Euro 

EPA U.S. Environmental Protection Agency 

GC/MS Gas chromatography/Mass Spectrograph 

HPLC High performance liquid chromatography 

ITER Innovative Technology Evaluation Report 

kg Kilogram 

LC50 Lethal concentration - 50 percent 

L/h Liters per hour 

m3 Cubic meters 

MCAWW Methods for Chemical Analysis of Water and Wastes 

MS/MSD Matrix spike/matrix spike duplicate 

m/p-xylene meta-xylene and para-xylene 

NPL National Priorities List 

NRMRL National Risk Management Research Laboratory 

NTIS National Technical Information Service 

o-xylene ortho-xylene 

ORD U.S. EPA Office of Research and Development 

OSWER U.S. Office of Solid Waste and Emergency Response 

QA/QC Quality assurance and quality control 

QAPP Quality assurance project plan 

QC Quality control 

RCRA Resource Conservation and Recovery Act 

RPD Relative percent difference 

SARA Superfund Amendments and Reauthorization Act (of 1986) 

SITE Superfund Innovative Technology Evaluation (program) 

Superfund Hazardous Substance Response Trust Fund 

SVOC Semivolatile organic compound 

SW-846 Test Methods for Evaluating Solid Waste 

Tauw Tauw Umwelt GmbH Moers 

Tetra Tech Tetra Tech EM Inc. 

μg/L M icrograms per liter 

VISITT Vendor Information System for Innovative Treatment Technologies 

VEGAS Versuchseinrichtung zur Grundwasser-und Altlastensanierung 

VOC Volatile organic compound 

vii 
To Convert Into Multiply By 

Centimeters Feet 0.0328 

Centimeters Inches 0.393 

Cubic meters Cubic feet 35.0 

Cubic meters Gallons 264 

Cubic meters Cubic yards 1.31 

Degrees Celsius Degrees Fahrenheit multiply by 1.80; add 

32 

Hectopascals Atmosphere 0.000986 

Kilograms per square meter Pounds per square inch, absolute 0.00142 

Kilograms Pounds 2.21 

Kilograms per liter Pounds per cubic foot 12.8 

Kilometers Miles (statute) 0.621 

Liters Gallons 0.265 

Liters per hour Gallons per minute 0.0044 

Liters per second Cubic feet (standard) per minute 2.12 

Meters Feet 3.278 

Millimeters Inches 0.039 

Square meters Square feet 10.764 

CONVERSION TABLE 

(Metric to English Units) 

viii 
ACKNOWLEDGMENTS

This report was prepared under the direction of Dr. Ronald Lewis of the EPA National Risk Management 

Research Laboratory (NRMRL) in Cincinnati, Ohio. This report was prepared by Mr. Roger Argus, Ms. 

Elizabeth Barr, and Mr. Steven Geyer of Tetra Tech EM Inc. Ms. Ann Vega of NRMRL, Mr. Burkhard 

Heuel-Fabianek of Probiotec, and Dr. Reiner Kurz of Institut Fresenius were contributors to, and 

reviewers of, this report. 

ix 
EXECUTIVE SUMMARY

This innovative technology evaluation report (ITER) summarizes the results of an evaluation of a 

surfactant-enhanced extraction technology. This evaluation was conducted under a bilateral agreement 

between the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation 

(SITE) program and the Federal Republic of Germany Ministry for Research and Technology (BMBF). 

To provide performance data for the evaluation, the surfactant-enhanced extraction system was 

demonstrated within an artificial aquifer from February 28 through March 5, 1998 at the 

Versuchseinrichtung zur Grundwasser-und Altlastensanierung (VEGAS) research facility in Stuttgart, 

Germany. Prior to the demonstration, the artificial aquifer was injected with xylene to create a 

contaminant plume for the technology evaluation. During the demonstration, surfactant was injected into 

the artificial aquifer, groundwater containing xylene was extracted, and the system was monitored to 

assess the effectiveness of the technology. 

The Surfactant-Enhanced Extraction Technology 

The use of surfactants to enhance in-situ flushing of aquifers for remediation of non-aqueous phase liquid 

contaminant plumes has not yet been accepted in Germany because of the limited availability of credible 

test data. In order to collect more reliable data, a large-scale test of surfactant-enhanced extraction was 

conducted at the VEGAS research facility. The technology demonstrated uses a proprietary surfactant 

developed by BASF AG and a surfactant recovery system developed by Tauw Umwelt GmbH Moers. 

VEGAS facility personnel installed and operated the treatment system. 

The VEGAS research facility was constructed to facilitate the evaluation of remediation technologies. An 

artificial aquifer has been constructed at the VEGAS facility to allow for controlled testing of in-situ 

treatment technologies. Thirty-one kilograms (kg) of xylene, an organic contaminant with low solubility 

in water, was injected into the artificial aquifer and “groundwater” flow was induced to stimulate a 

contaminant plume. Groundwater was sampled by the BMBF support contractors, ArGe focon-Probiotec 

and Institut Fresenius, with assistance from the EPA support contractor, Tetra Tech EM Inc. (Tetra Tech). 

System operating parameters were monitored by VEGAS personnel. All samples were analyzed by the 

Institut Fresenius laboratory in Taunusstein. The groundwater effluent from the aquifer was treated using 

a conventional water treatment system and recycled into the aquifer. The conventional water treatment 

system consisted of a sedimentation tank, a phase separator, a sand filter, and a granular activated carbon 

bed. 

The proprietary surfactant was designed to enhance the removal of volatile organic compounds (VOCs), 

including xylene, from the saturated zone by increasing the partitioning of those compounds into the 

ES-1 
groundwater phase, which is then extracted. The above-ground surfactant recovery system was designed 

to separate the surfactant from the extracted groundwater for recycling. This system included an air 

stripper to remove xylene from the extracted groundwater, a membrane filter to recover surfactant, and a 

bioremediation unit to treat permeate from the membrane filter. Therefore, the only wastewater stream 

from the system is the treated permeate stream. Five original sample and measurement points were 

identified to evaluate the process. Due to a change in the process configuration, sample location S6 and 

measurement location M6 were added. Specifically, the Tauw surfactant recovery system was not 

operational during the demonstration, as is described in more detail in Section 2.2.2. Therefore, it was 

not possible to obtain recycled water from the Tauw surfactant recovery system for reinjection. During 

Phase 1 of the process operations (water injection only), this equipment unavailability was overcome by 

passing the extracted groundwater through a carbon filter, and then recycling the carbon-treated 

groundwater back to the injection well or hydraulic control wells (see Figure 8, Diagram 1). 

The groundwater effluent from the artificial aquifer is treated with a conventional water treatment system 

at the VEGAS facility and recycled into the artificial aquifer, forming a continuous loop of groundwater 

flow. The conventional water treatment system consists of a sedimentation tank, a phase separator, a sand 

filter, and a granular activated carbon bed. 

Demonstration Conclusions 

The conclusions of the surfactant-enhanced extraction technology demonstration are summarized below: 

• The xylene mass removal rate increased as a result of the surfactant enhancement. Specifically, 

the concentration of xylene in the extracted groundwater increased by a factor of approximately 

15 after the injection of the surfactant solution. 

• There was no significant increase in the xylene concentration of the groundwater exiting the 

artificial aquifer as a result of the surfactant enhancement. Average groundwater effluent xylene 

concentrations were 19.8 micrograms per liter (μg/L) before surfactant injection, 7.7 μg/L during 

surfactant injection, and 2.3 μg/L following surfactant injection. 

• The toxicity results indicate that the extracted groundwater was not sufficiently toxic to kill 50 

percent of the Daphnia test organisms, even at no dilution. 

• The process operational parameters were as follows: extracted groundwater flow rates ranged 

from 116 to 230 liters per hour (L/h); injected groundwater flow rates ranged from 101.4 to 112 

L/h. Influent groundwater flow rates ranged from 207 to 252 L/h; and effluent groundwater flow 

rates ranged from 191 to 315 L/h. The groundwater influent temperature ranged from 18.5 to 

19.1 C and the pH ranged from 7.53 to 7.9. The above ground surfactant recycling system was 

not operational and was not used during the evaluation; therefore, the surfactant was not 

separated and recycled. 

ES-2 
• The surfactant concentrations in the effluent groundwater were all less than 0.05 milligrams per 

liter (mg/L) for anionic surfactants and less than 0.25 mg/L for nonanionic surfactants. The 

treated permeate was not analyzed since the recovery system was not operational. 

• The cost of the surfactant provided by BASF was 1.78 Euros (€) per kilogram of surfactant 

($2.33 per kilogram assuming a 0.76 € to $1 U.S. exchange rate). Because the surfactant 

recovery system was not operational during the demonstration and the ability to recycle surfactant 

was not determined, a detailed cost analysis could not be developed. 

Technology Applicability 

The surfactant-enhanced extraction technology demonstrated at the VEGAS facility accelerated the 

removal of xylene from the artificial aquifer. The developer claims that in addition to xylene, the 

technology can also remove other non-aqueous phase liquids from the saturated zone. The surfactantenhanced extraction technology provides both short-term and long-term protection of human health and 

the environment by reducing the concentrations of non-aqueous phase liquid contaminants in the 

saturated zone. Because the contaminants are permanently removed, the toxicity, mobility, and volume of 

contaminants are also significantly reduced. Minimal adverse impacts to the community, workers, or the 

environment are anticipated during site preparation, system installation, and system operation. 

Site preparation and access requirements for the technology can be significant. The contamination plume 

at the site must be in an aquifer where hydraulic control can be maintained. Operation and maintenance 

of the large network of surfactant injection and groundwater extraction wells requires competent technical 

and engineering personnel to be available at all times. 

ES-3 
1.0 INTRODUCTION 

This report documents the findings of an evaluation of a surfactant-enhanced extraction 

technology for removal of non-aqueous and volatile organic compounds (VOCs) liquid 

contaminants from the saturated zone. This evaluation was conducted under a bilateral agreement 

between the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology 

Evaluation (SITE) program and the Federal Republic of Germany Ministry for Research and 

Technology (BMBF). 

The technology was demonstrated from February 28 through March 5, 1998 at the 

Versuchseinrichtung zur Grundwasser-und Altlastensanierung (VEGAS) research facility in 

Stuttgart, Germany (see Figure 1). The VEGAS research facility was constructed to facilitate the 

evaluation of remediation technologies and includes an artificial aquifer to allow for controlled 

testing of in-situ technologies. Thirty-one kilograms (kg) of xylene, an organic contaminant with 

low solubility in water, was injected into the artificial aquifer at four different locations (and at 

four depths), and “groundwater” flow was induced to stimulate a contaminant plume. 

The surfactant-enhanced extraction technology was demonstrated at the VEGAS facility to 

evaluate its effectiveness in enhancing the removal of a light non-aqueous liquid, specifically 

xylene, from the artificial aquifer. Groundwater was sampled by a field team of personnel from 

the BMBF support contractors, Institut Fresenius and ArGe focon-Probiotec, with assistance from 

the EPA technical support contractor, Tetra Tech EM Inc. (Tetra Tech). System operating 

parameters were monitored by VEGAS personnel. All samples were analyzed by the Institut 

Fresenius laboratory in Taunusstein. All demonstration activities were conducted in accordance 

with the February 1998 quality assurance project plan (QAPP) (Tetra Tech 1998). 

The technology demonstration involved three test phases: Phase I - Groundwater flow in the 

artificial aquifer with injection and extraction of water only (pump and treat without surfactants); 

Phase II - Groundwater flow in the artificial aquifer with surfactant injection and extraction of 

groundwater; and Phase III - Groundwater flow in the artificial aquifer with the injection and 

extraction of groundwater only to remove residual surfactant. Groundwater samples were 

collected and flow rates were measured during each phase. VEGAS personnel conducted routine 

monitoring and adjusted the extraction flow rates during the initiation of each phase of the 

demonstration. Once VEGAS personnel had initiated each phase, Institut Fresenius personnel 

collected the necessary groundwater samples. The decision of when to begin injection of 

surfactants was made by VEGAS personnel. 

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This report documents the results of the demonstration and provides information that is intended 

to be useful to remedial managers, environmental consultants, and other potential technology 

users in implementing surfactant-enhanced extraction technologies at contaminated sites. Section 

1.0 presents an overview of the SITE program and bilateral agreement, describes the technology, 

and lists key contacts. Section 2.0 presents information relevant to the technology’s 

effectiveness, including contaminated aquifer characteristics and process flow diagrams, 

demonstration procedures, and the results and conclusions of the evaluation. Section 3.0 presents 

information on the costs associated with applying the technology. Section 4.0 presents 

information relevant to the technology’s application, including assessment of the technology 

related to nine feasibility study evaluation criteria used for decision making in the Superfund 

process. Section 4.0 also discusses applicable wastes/contaminants and limitations of the 

technology. Section 5.0 summarizes the technology status, and Section 6.0 lists references used 

in preparing this report. 

1.1 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION PROGRAM 

This section provides background information about the U.S. Superfund law and the EPA SITE 

program. Additional information about the SITE program, the surfactant-enhanced extraction 

technology, and the technology demonstration can be obtained by contacting the key individuals 

listed in Section 1.4. 

Past hazardous waste disposal practices and their human health and environmental impacts 

prompted the U.S. Congress to enact the Comprehensive Environmental Response, 

Compensation, and Liability Act (CERCLA) of 1980 (PL96-510). CERCLA established a 

Hazardous Substance Response Trust Fund (Superfund) to pay for handling emergencies at and 

cleaning up uncontrolled hazardous waste sites. Under CERCLA, EPA has investigated these 

hazardous waste sites and established national priorities for site remediation. The ultimate 

objective of the investigations is to develop plans for permanent, long-term site cleanups, 

although EPA initiates short-term removal actions when necessary. EPA’s list of the nation’s 

top-priority hazardous waste sites that are eligible to receive federal cleanup assistance under the 

Superfund program is known as the National Priorities List (NPL). 

As the Superfund program matured, Congress expressed concern over the use of land-based 

disposal and containment technologies to mitigate problems caused by releases of hazardous 

substances at hazardous waste sites. As a result of this concern, the 1986 reauthorization of 

CERCLA, called the Superfund Amendments and Reauthorization Act (SARA), mandates that 

EPA “select a remedial action that is protective of human health and the environment, that is cost 

3 
effective, and that utilizes permanent solutions and alternative treatment technologies or resource 

recovery technologies to the maximum extent practicable.” 

 In response to this requirement, EPA established the SITE program to accelerate the 

development, demonstration, evaluation, and use of innovative technologies for site cleanups. 

The SITE program has four goals: 

• Identify and remove impediments to development and commercial use of innovative 

technologies, where possible 

• Conduct demonstrations of the more promising innovative technologies to establish 

reliable performance and cost information for site characterization and cleanup decisionmaking 

• Develop procedures and policies that encourage selection of effective innovative 

treatment technologies at uncontrolled hazardous waste sites 

• Structure a development program that nurtures emerging technologies 

Each year EPA selects the best available innovative technologies for demonstration evaluation. The 

screening and selection process for these technologies is based on four factors: (1) the technology’s 

capability to treat Superfund wastes, (2) expectations regarding the technology’s performance and cost, 

(3) the technology’s readiness for full-scale demonstrations and applicability to sites or problems needing 

remedy, and (4) the developer's capability for and approach to testing. SITE program demonstration 

evaluations are administered by EPA’s Office of Research and Development (ORD) through the National 

Risk Management Research Laboratory (NRMRL) in Cincinnati, Ohio. 

SITE demonstration evaluations are usually conducted at uncontrolled hazardous waste sites such as EPA 

removal and remedial action sites, sites under the regulatory jurisdiction of other federal agencies, state 

sites, EPA testing and evaluation facilities, sites undergoing private cleanup, the technology developer’s 

site, or privately owned facilities. In the case of the surfactant-enhanced extraction technology 

demonstration, the VEGAS site was selected cooperatively by EPA and BMBF. The EPA-BMBF 

bilateral agreement is discussed in Section 1.2. 

SITE and bilateral SITE demonstration evaluations provide detailed data on the performance, cost 

effectiveness, and reliability of innovative technologies. These data will provide potential users of a 

technology with sufficient information to make sound judgments about the applicability of the technology 

to a specific site or waste and to allow comparisons of the technology to other treatment alternatives. 

4 
EPA established the SITE program to accelerate the development, demonstration, and use of innovative 

technologies to remediate hazardous waste sites. The demonstration portion of the SITE program focuses 

on technologies in the pilot-scale or full-scale stage of development. 

The evaluations conducted during SITE technology demonstrations are intended to generate performance 

data of known quality. Therefore, sampling and analysis procedures are critical and approved quality 

assurance and quality control (QA/QC) procedures are stringently applied as part of all technology 

evaluations under SITE. 

1.2 BILATERAL AGREEMENT BETWEEN THE UNITED STATES AND GERMANY ON 

REMEDIATION OF HAZARDOUS WASTE SITES 

In April 1990, EPA and BMBF entered into a bilateral agreement to gain a better understanding of each 

country’s efforts in developing and demonstrating remedial technologies. The bilateral agreement has the 

following goals: 

• Facilitate an understanding of each country’s approach to remediation of contaminated 

sites 

• Demonstrate innovative remedial technologies as if the demonstrations had taken place in 

each country 

• Facilitate international technology exchange 

Technologies in the U.S. and in Germany are evaluated under the bilateral agreement. Individual or, in 

some cases, multiple remedial technologies are demonstrated at each site. Technology evaluations 

occurring in the U.S. correspond to SITE demonstrations; those occurring in Germany correspond to fullscale site remedial activities and are referred to as bilateral SITE demonstrations. In the case of the U.S. 

evaluations, technology evaluation plans are prepared following routine SITE procedures. Additional 

monitoring and evaluation measurements required for evaluation of the technology under German 

regulations will be specified by the German partners. For the demonstrations occurring in Germany, the 

German partners provide all required information to allow the U.S. to develop an EPA NRML QAPP. An 

EPA-approved QAPP entitled “Quality Assurance Project Plan for the Surfactant-Enhanced Extraction 

Technology Evaluation” and dated February 1998 was prepared for this technology evaluation (Tetra 

Tech 1998). 

ArGe focon-Probiotec (a partnership of two German environmental consulting firms) was commissioned 

by BMBF to compile summary reports for the German technologies and sites, to evaluate the U.S. 

demonstration plans, and to facilitate the bilateral agreement on behalf of BMBF. The ArGe foconProbiotec technical consulting partnership is not directly involved in the German remedial actions, and 

5 
the partnership does not influence actual site remediation activities. Tetra Tech has been contracted by 

the U.S. EPA to provide comprehensive technical support to U.S. evaluations and to coordinate U.S. 

activities for bilateral SITE evaluations. The bilateral project organization is presented in Figure 2. 

1.3 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY DESCRIPTION 

Surfactants and other chemicals have recently been applied as enhancements to conventional soil flushing 

technology to accelerate the in situ extraction of contaminants from the saturated zone. In conventional 

soil flushing, water is circulated through a contaminated zone to wash out chemical contaminants. The 

use of surfactants in the circulated water can increase the mobility or solubility of many organic 

contaminants, including particularly non-aqueous phase liquids (NAPLs), further facilitating extraction. 

Specifically, surfactants can disperse and solubilize NAPLs through the formation of micelles. 

The use of surfactants to enhance in situ soil flushing has not yet been accepted in Germany because 

limited credible test data are available for this technology. In order to collect more reliable data, a pilotscale demonstration of in situ surfactant-enhanced extraction was conducted at the VEGAS research 

facility. 

The specific surfactant-enhanced extraction technology evaluated during this bilateral SITE 

demonstration employs a proprietary mixture of anionic and nonionic surfactants developed by BASF AG 

(BASF) and a surfactant recovery system developed by Tauw Umwelt GmbH Moers (Tauw). The 

surfactant recovery system incorporates an air stripper to remove xylene from the extracted water stream, 

a membrane filter to recover surfactant, and a bioremediation unit to treat permeate from the membrane 

filter. These two components of the surfactant-enhanced extraction technology provide for the 

accelerated extraction of NAPL contaminants and for the separation of the surfactant mixture so that it 

can be recycled. 

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1.4 KEY CONTACTS 

Additional information on the surfactant-enhanced extraction technology and the EPA-BMBF bilateral 

technology evaluation program can be obtained from the following sources: 

Surfactant-Enhanced Extraction Technology 

 Reinhold Josef 

VEGAS Project Manager 

Institut fur Wasserbau 

 Universitat Stuttgart 

 Pfaffenwaldring 61 

 70550 Stuttgart 

07 11 / 685 7023 

EPA-BMBF Bilateral Technology Evaluation Program 

Annette Gatchett Bilateral Program Manager 

U.S. Environmental Protection Agency

Office of Research and Development 

26 West Martin Luther King Drive 

Cincinnati, Ohio 45268 

513-569-7697 

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

• The Alternative Treatment Technology Information Center (ATTIC) System (operator: 703­

908-2137) is a comprehensive, automated information retrieval system that integrates data on 

hazardous waste treatment technologies into a centralized, searchable source. This data base 

provides summarized information on innovative treatment technologies. 

• The Vendor Information System for Innovative Treatment Technologies (VISITT) (Hotline: 

800-245-4505) data base contains current information on nearly 350 technologies submitted 

by nearly 210 developers, manufacturers, and suppliers of innovative treatment technology 

equipment and services. 

• The Office of Solid Waste and Emergency Response (OSWER) Clean-up Information (CLUIN) electronic bulletin board contains information on the status of SITE technology 

evaluations. Its web site is www.clu-in.org. 

8 
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 (513) 569-7562. Additional 

information is available on the EPA home page at: www.epa.gov/oerrpage/superfund/sites. 

9 
2.0 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY EFFECTIVENESS 

This section provides background information and documents the field and analytical procedures as well 

as the operation of the process during the demonstration. This section further describes the results and 

conclusions of the surfactant-enhanced extraction technology demonstration. 

2.1 DEMONSTRATION BACKGROUND 

The bilateral SITE evaluation of the surfactant-enhanced extraction technology was conducted at the 

VEGAS research facility in Stuttgart, Germany. Xylene, an organic contaminant with low solubility in 

water, was injected into an artificial aquifer and groundwater flow was induced to stimulate a contaminant 

plume. The surfactant-enhanced extraction technology was then applied to remove the xylene 

contaminant from the artificial aquifer. 

2.1.1 VEGAS Research Facility 

The VEGAS research facility was constructed to facilitate the evaluation of remediation technologies. At 

the VEGAS facility, an artificial aquifer has been constructed to allow for controlled testing of in situ 

technologies. The artificial aquifer is located in a container that has a length of approximately 9 meters, a 

width of approximately 6 meters, and a depth of approximately 4.5 meters. The artificial aquifer within 

the container was constructed with inclined layers of sand (fine, medium, and coarse sand) resulting in 

hydrologic strata with differing hydraulic permeabilities. The permeability (kf value) of the three kinds 

of sand strata have been determined by VEGAS personnel using tracer studies. The value of kf was 

determined to be 3.2 x 10-4 meters per second for fine sand, 12.0 x 10-4 meters per second for medium 

sand, and 35 x 10-4 meters per second for coarse sand. A cross-section of the artificial aquifer is shown 

in the Figure 3. 

The container is fitted with 378 sampling and monitoring probes that are available to technology 

developers to monitor and control system operation. These probes can be used to measure the height of 

the water table, to monitor the hydraulic conditions during the experiment, and to sample the 

groundwater. 

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“Groundwater” is fed to the container through a permeable wall to maintain a flow of approximately 180 

liters per hour. The groundwater table in the container is approximately 3.70 meters from the bottom of 

the container. A hydraulic gradient of 0.6 percent is maintained for groundwater flow. 

2.1.2 Preparation of the Artificial Aquifer 

For the demonstration of the surfactant-enhanced extraction technology, six wells were installed in the 

container and labeled MW 1 through MW 6, as shown in Figure 4. The wells labeled MW 1, MW 2, MW 

4, and MW 5 were screened across the top two strata. MW 3 was screened across two intervals: the top 

strata and the bottom strata. MW 6 was screened from 90 centimeters (cm) to 185 cm below the top to 

the well casing. 

Approximately 3 months prior to the demonstration, on November 25, 1997, 31 kilograms (kg) of xylene 

solution were injected into the aquifer at four different locations between MW 1 and MW 4 and at four 

depths (a total of 16 injection points) . After termination of the four injections at the first depth, the 

groundwater table was raised to just above the first injection depth. The injection at the next depth was 

then made and the groundwater table was raised again. This process was repeated for each of the 

specified depths and, after the final xylene injection, the groundwater was raised to result in a saturated 

thickness of 3.70 meters above the bottom of the artificial aquifer. Analysis of samples collected from the 

groundwater effluent before application of the surfactant-enhanced extraction technology indicated a 

relatively constant xylene concentration of about 20 milligrams per liter. 

2.1.3 Process Description and Planned Operation 

This section describes the system that was installed and the planned mode of operation. It should be 

noted that the actual operation changed from these plans as described in Section 2.2.4. 

A simplified flow diagram of the surfactant-enhanced extraction system that was installed at the VEGAS 

facility is shown in Figure 5. Originally, only five wells were installed in the container (MW 1 through 

MW 5); it was planned that the surfactant solution would be injected into MW 1 at approximately 50 

liters per hour (L/h) and extracted from MW 2 at 200 L/h. Further, MW 4 and MW 5 were to serve as 

hydraulic control wells through the injection of 75 L/h of groundwater into each well. However, it was 

later decided to install a sixth well (MW 6) and to alter the planned hydraulic flow scheme as follows: 

12 
    

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• MW 1 and MW 4 - Not used 

• MW 2 and MW 5 - Hydraulic control wells 

• MW 3 - Extraction well 

• MW 6 - Surfactant/groundwater solution injection well 

Thus, in the revised hydraulic flow scheme, surfactant solution is injected through MW 6 and extracted 

through MW 3. After processing in the surfactant recovery system to remove the extracted xylene and to 

separate the surfactant, the extracted groundwater is recycled to supply the hydraulic control wells (MW 2 

and MW 5) as well as the injection well (MW 6). This is the flow scheme that was ultimately 

implemented at the VEGAS facility. 

The above-ground surfactant recovery system includes an air stripper to remove xylene from the extracted 

water stream, a membrane filter to recover surfactant, and a bioremediation unit to treat permeate from the 

membrane filter. A schematic flow diagram is shown as Figure 6. The only wastewater stream from this 

system is the treated permeate stream. The system was designed to meet German discharge limits for the 

treated permeate, which are 0.5 milligrams per liter (mg/L) for xylene (a VEGAS facility permit 

requirement) and 200 mg/L for surfactants (a self-imposed limit not required by the VEGAS facility 

permit). 

The groundwater effluent from the artificial aquifer is treated with a conventional water treatment system 

at the VEGAS facility and recycled into the artificial aquifer, forming a continuous loop of groundwater 

flow. The conventional water treatment system consists of a sedimentation tank, a phase separator, a sand 

filter, and a granular activated carbon bed. 

The surfactant enhanced extraction technology is implemented in three phases: 

• Phase I - groundwater flow in the artificial aquifer with injection and extraction of water only 

(pump and treat without surfactants) 

• Phase II - groundwater flow in the artificial aquifer with surfactant injection and extraction of 

groundwater 

• Phase III - groundwater flow in the artificial aquifer with the injection and extraction of water 

only to remove residual surfactant 

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Figure 7 is a conceptual plot of the anticipated contaminant mass removal rates during these three 

operational phases. As shown in this figure, contaminant mass removal rates increase dramatically 

immediately following the initiation of surfactant injection. After two days of surfactant injection, much 

of the extractable contaminant mass is removed from the aquifer and removal rates begin to decline. At 

this point, surfactant injection is stopped, and the surfactant as well as residual contaminant is washed out 

of the aquifer through continued injection of water alone. 

2.1.4 Demonstration Objectives and Approach 

Demonstration objectives were selected to provide potential users of the system with the necessary 

technical information to assess the applicability of the treatment system to other contaminated sites. 

Primary objectives and secondary objectives bilateral were developed and agreed upon for this SITE 

demonstration. 

The primary objectives and associated critical measurements to evaluate these objectives are listed in 

Table 1. The secondary project objectives and associated non-critical measurements required to evaluate 

those objectives are listed in Table 2. 

TABLE 1. CRITICAL MEASUREMENT PARAMETERS 

Primary Objective Measurement Parameters 

P1. Determine whether xylene mass removal rate 

increases due to surfactant enhancement. 

Flow rate and concentration of xylene in the 

extracted groundwater during three test 

phases. 

P2. Verify that there is no statistically significant 

increase in xylene concentrations in groundwater 

exiting the artificial aquifer due to surfactant 

enhancement. 

Concentration of xylene in groundwater 

effluent from the artificial aquifer to 

determine whether xylene mobilized by the 

surfactant is captured in the extracted 

groundwater. 

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TABLE 2. NONCRITICAL MEASUREMENT PARAMETERS

Secondary Objective Measurement Parameter 

S1. Evaluate the acute toxicity of the treated 

permeate from the surfactant recovery system 

and of groundwater effluent from the artificial 

aquifer before and after surfactant injection. 

LC50 acute tests on samples of surfactant 

recycling system permeate and groundwater 

effluent. 

Toxicity tests on samples of influent groundwater 

to provide a baseline. 

S2. Document process operating parameters. Process operating parameters: influent and 

effluent groundwater, injected 

surfactant/groundwater solution, and extracted 

groundwater flow rates; surfactant use rates; and 

flow rate of treated permeate. 

Documentation of soil and stratigraphic 

information, and any operational problems and 

difficulties as well as resolutions. 

Measurement of physical/chemical groundwater 

parameters (temperature; pH; conductivity, and 

metals content) in three samples collected from the 

influent groundwater to the artificial aquifer. 

S3. Document the xylene and surfactant 

concentration in the treated surfactant recovery 

permeate and surfactant concentration in the 

effluent groundwater. 

Analysis of samples of treated surfactant recovery 

permeate for total xylene according to EPA 

method SW-846 8260B (EPA 1996) and 

surfactants according to Standard Method 5540C 

and D (APHA et al. 1994). 

Analysis of samples of groundwater effluent from 

the artificial aquifer for surfactants according to 

Standard Method 5540C. 

S4. Estimate capital and operating costs. Based on (1) process operating parameters 

mentioned above, (2) operating requirements 

observed during the evaluation, and (3) capital 

costs and operating information provided by 

VEGAS and Tauw. 

Notes: 

EPA U.S. Environmental Protection Agency

 LC50 Lethal concentration - 50 percent 

SW-846 Test Methods for Evaluating Solid Waste 

VEGAS Versuchseinrichtung zur Grundwasser-und Altlastensanierung 

19 
To perform the measurements needed to meet each of the objectives, samples were collected and analyzed 

and field data were recorded using the methods and procedures summarized in the following section. 

2.2 DEMONSTRATION PROCEDURES 

This section describes the methods and procedures used to collect and analyze samples for the bilateral 

SITE evaluation of the surfactant-enhanced extraction technology and discusses the operation of the 

process during the demonstration. 

2.2.1 Sampling and Analysis Program 

This section describes the sampling and analysis program, including sample collection frequencies and 

locations. 

2.2.1.1 Sampling and Measurement Locations 

Sampling and measurement locations were selected based on the configuration of the treatment system 

and project objectives. These locations are shown in Figure 8 and include the following sampling ports: 

• Location S1: The groundwater influent sampling port 

• Location S2: The groundwater effluent sampling port 

• Location S3: The surfactant/water injection stream port 

• Location S4: The groundwater extraction stream sampling port. 

• Location S5: Not used 

• Location S6: The conventional groundwater treatment system effluent sampling port 

These locations also include the following flow measurement points: 

• Location M1: The extracted groundwater 

• Location M2: The injected surfactant/water solution rotameter 

• Location M3: The influent groundwater 

• Location M4: The effluent groundwater 

• Location M5: Not used 

• Location M6: The injected water for hydraulic control (MW 5 and MW 2) 

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It should be noted that sample location S6 and measurement location M6 were added to the list of five 

original sample points, and sample location S5 and measurement location M5 were deleted due to a 

change in the process configuration. Specifically, the Tauw surfactant recovery system was not 

operational during the demonstration, as is described in more detail in Section 2.2.2. Therefore, it was 

not possible to sample or monitor the permeate or to obtain recycled water from the Tauw surfactant 

recovery system for reinjection. During Phase I of the process operations (water injection only), this 

equipment unavailability was overcome by passing the extracted groundwater through a carbon filter, and 

then recycling the carbon-treated groundwater back to the injection well or hydraulic control wells (see 

Figure 8, Diagram 1). 

The groundwater effluent from the artificial aquifer is treated with a conventional water treatment system 

at the VEGAS facility and recycled into the artificial aquifer, forming a continuous loop of groundwater 

flow. The conventional water treatment system consists of a sedimentation tank, a phase separator, a sand 

filter, and a granular activated carbon bed. 

2.2.2 Sampling and Analytical Methods 

This section briefly summarizes the sampling frequencies and procedures as well as analytical methods 

used during the evaluation. Details of these sampling procedures and analytical methods are described in 

the QAPP (Tetra Tech 1998). 

Groundwater samples were collected at the six locations described in the Section 2.2.1. Grab sampling 

techniques were employed for all samples taken from the designated sampling ports throughout the 

demonstration. Samples of major process streams (the injected and extracted groundwater as well as the 

influent and effluent groundwater) were collected approximately every 4 hours. Samples of other 

process streams were taken either once per day or once per phase, as specified in the QAPP. 

Table 3 lists the analytical procedures used to measure the parameters of interest for the samples collected 

during the demonstration. These measurements were made on the samples collected from all locations. 

Flow rates were measured by in-line flow meters maintained by VEGAS personnel. 

22 
TABLE 3. ANALYTICAL METHODS

SURFACTANT-ENHANCED EXTRACTION SYSTEM

Method Source Parametera Name of Method 

SW-846 8260B VOCs VOCs by GC/MS: Capillary Column Technique 

(preparation method is included in 8260B) 

EPA/600/4-90/027 Acute toxicity 48-hour Static Acute Toxicity Test (Definitive) Using 

Ceriodaphnia dubia (C. dubia) 

SW-846 

3010A/6010A 

Metals Acid digestion of Aqueous Samples/Inductively coupled PlasmaAtomic Emission Spectroscopy 

MCAWW 170.1 Temperature Temperature 

SW-846 9040B pH pH Electrometric Measurement 

SW-846 9050 Conductivity Specific Conductance 

SM 5540C and D Surfactants Surfactants 

Notes: 

VOCs Volatile Organic Compounds 

GC/MS Gas Chromatograph/Mass Spectrograph 

MCAWW Methods for Chemical Analysis of Water and Wastes (EPA, 1983) 

SW-846 Test Methods for Evaluating Solid Waste (EPA, 1996) 

2.2.3 Quality Assurance and Quality Control Program 

Quality control checks were an integral part of the bilateral SITE demonstration to ensure that the QA 

objectives were met. These checks and procedures focused on the collection of representative samples 

absent of external contamination and on the generation of data of acceptable precision and accuracy. The 

QC checks and procedures conducted during the demonstration were of two kinds: (1) checks controlling 

field activities, such as sample collection and shipping, and (2) checks controlling laboratory activities, 

such as extraction and analysis. The results of the field and laboratory QC checks are summarized in 

Section 2.3.3. 

No project specific field or laboratory audits were conducted during this technology demonstration. 

However, general systems audits of Institut Fresenius have been conducted under other bilateral 

technology demonstrations. 

2.2.4 Chronology of Process Operations and Changes to the Sampling Program 

This section summarizes the operation of the surfactant-enhanced extraction system during the bilateral 

SITE demonstration. The system was operated from February 28, 1998 at 5:00 p.m. (beginning of Phase 

23 
I sampling) to March 5, 1998 at 11:00 a.m. (end of Phase III), for a total of 114 hours. The Tauw 

surfactant recovery system was not fully operational, and therefore, sampling of the permeate was not 

performed during the demonstration. 

As planned, the process was operated and samples were collected in three test phases. The purpose of 

Phase I (injection and extraction of water only) was simply to establish steady state operation prior to the 

injection of any surfactants. Phase II incorporated the surfactant injection into MW 6 and the enhanced 

removal of xylene in the groundwater extracted from MW 3. Phase III returned to water-only injection to 

MW 6 to remove the residual surfactant for recovery. The injection and extraction rates during each 

phase were set by VEGAS personnel during startup of that phase based on the planned flow rates and 

observed operational conditions. Injection into hydraulic control wells MW 2 and MW 5 was maintained 

during Phases II and III. 

Several changes to the planned operation of the system were implemented during the demonstration by 

VEGAS operational personnel. As a result, the on-site personnel from the bilateral SITE sampling team 

had to adapt some sampling procedures to meet the demands of the revised process operations. A 

chronology of the process operations and descriptions of the changes to planned procedures is included 

below. For convenience, all references to the timing of events during the demonstration are hereinafter 

referred to by hour and minute using the initiation of Phase I as Time 00:00. 

Phase I 

Time 00:00. The initial injection rate into MW 6 and the extraction rate from MW 3 were set at 

approximately 120 L/h. The water extracted from MW 3 was passed through an activated carbon bed 

prior to recycling to MW 6, since the Tauw surfactant recovery system was not yet operational. No 

injection into MW 2 or MW 5 was conducted since these wells were for hydraulic control during 

surfactant injection. 

Time 26:00 to 28:00. To prepare for the surfactant injection, the pumping rate at the extraction well 

(MW 3) was increased to approximately 200 L/h. To compensate for this increase and maintain the water 

balance in the aquifer container, water from the VEGAS water treatment system was pumped into the 

aquifer at MW 2 and MW 5 at a rate of approximately 80 L/h. 

Time 49:00. The last Phase I samples were taken. 

24 
Phase II 

Time 50:00. The pumping configuration was changed by increasing the pumping rate at MW 3 to 200 

L/h. As a result of the change in the pumping configuration for the extraction of water, concern arose as 

to whether the hydraulic conditions of the aquifer might have been altered. The U.S.-German Bilateral 

team decided that additional samples of the extracted groundwater would be collected for xylene analysis 

at half-hour intervals from Time 54:30 to Time 60:00 and at 1-hour intervals from Time 60:00 to Time 

87:00. The purpose of these samples was to determine whether changes in the hydraulic conditions 

affected the xylene concentration at the extraction well and to track the arrival of the surfactant at the 

extraction well. This sampling period was designated as Phase IIa, and the samples were labeled 

accordingly. Subsequent to this decision, some additional adjustments to the sampling times were 

necessary throughout the remainder of Phase II because of various technical modifications (for example, 

air in the lines precluding effective sampling, thereby requiring a new sampling point to be installed). 

Time 50:20. The injection of surfactant began at MW 6. The surfactant was a 2.2 percent solution of the 

BASF proprietary mixture. The volume of surfactant solution was 2.7 cubic meters (m3) and was 

contained in a 12 m3 vat in the basement of the VEGAS research facility. The vat employed a stirring 

mechanism to keep the solution mixed. A pump was used to inject the surfactant solution and 

groundwater into MW 6 at a rate of 100 to 120 L/h. 

Time 61:00. Foaming was noted in the water extracted from MW 3. This indicated that the surfactant 

had migrated to the extraction well and that the corresponding travel time from the injection well (MW 6) 

to the extraction well (MW 3) was approximately 11 hours or less. 

Time 70:00. The vat containing the surfactant ran dry. The surfactant had been injected into MW 6 for 

approximately 20 hours. The input to the injection well was switched from the surfactant vat to water 

from the VEGAS on-site water treatment system. This water was sampled twice (once on March 3 and 

once on March 4, 1998) for toxicity tests. No additional samples were collected at MW 6 following the 

completion of surfactant addition. 

On the third day of operation, Tauw was unable to get their surfactant recovery system to operate as 

intended; therefore, no treated permeate samples were collected. All water and surfactant extracted at 

MW 3 was collected for processing through the Tauw system and stored in a 12 m3 storage tank in the 

basement of the VEGAS research facility. Phase II sampling continued through the fourth day of 

operation. During the fifth day of operation, the xylene concentration in a grab sample from MW 3 was 

determined by on-site high performance liquid chromatography (HPLC) to be 270 milligrams per liter 

(mg/L). Also, water could not be injected into MW 2 so all 80 L/hr of flow for hydraulic control was 

being injected into MW 5. 

25 
Phase III 

Time 110:00. Phase III began on the morning of March 5, 1998. A grab sample collected in midmorning from MW 3 was analyzed by on-site HPLC and contained a xylene concentration of 85 mg/L. 

This analysis confirmed the beginning of Phase III because this was the first sign of a decreased xylene 

concentration in the extracted groundwater. A grab sample also was collected from the extracted 

groundwater storage tank; the xylene concentration in this sample was 500 mg/L. 

Time 114:00. The 12 m3 storage tank was noted to be full and therefore the demonstration was ended 

shortly after. Because Tauw continued to be unable to get their surfactant recovery system to operate as 

intended, no treated permeate samples were collected during the demonstration. 

2.3 DEMONSTRATION RESULTS AND CONCLUSIONS 

This section presents the results of the field measurements and groundwater sampling and analysis 

conducted over the 5-day period of the demonstration. This section then describes the conclusions of the 

bilateral SITE demonstration of the surfactant-enhanced extraction technology. 

2.3.1 Results and Discussion 

The results of the bilateral SITE demonstration of the surfactant-enhanced extraction technology are 

presented below in relation to the project objectives. In each subsection below, the specific primary or 

secondary objective is shown in italics, followed by a discussion of the objective-specific results. Data 

quality and conclusions based on these results are presented in Sections 2.3.3 and 2.3.4, respectively. 

2.3.1.1 Primary Objective P-1 

Determine whether the xylene mass removal rate increases due to surfactant enhancement. 

To determine the mass removal rate, samples of groundwater entering and exiting the system were 

collected during the three test phases. The mass removal rate was calculated based on the measured flow 

rates and xylene concentrations in the extracted groundwater from the artificial aquifer. 

The xylene mass removal rates were calculated using the xylene concentration data from samples 

collected at S4 and the flow rate of the extracted groundwater measured at M1. 

26 
 Specifically, the mass removal rates were calculated by multiplying each xylene concentration by the 

flow rate at the time each sample was collected, as listed in Table 4. A graph of the removal rate over all 

three phases of the demonstration is shown in Figure 9. The figure shows a mass removal rate pattern that 

is consistent with what was expected (Figure 7). However, at Time 76:00, an anomalous decrease in the 

xylene concentration from 500 to 126 mg/L was noted. This anomalous data point appears to be related 

to an increase in the injection rate of groundwater (from 93 to 189 L/h) at MW 5 at that time due to 

plugging in the second hydraulic control well (MW 2). 

2.3.1.2 Primary Objective P-2 

Verify that there is no statistically significant increase in xylene concentrations in groundwater exiting 

the artificial aquifer due to surfactant enhancement. 

TABLE 4. XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER 

(SAMPLING LOCATION S4, MONITORING LOCATION M1) 

Sample 

Description 

Sampling Date 

and 

Time 

Total Xylene 

Concentration 

(μg/L) 

Flow Rate 

(L/h) 

Xylene Mass 

Removal Rate 

(μg/h) 

Phase I 

1-1-1-1 

2/28/98 

00:00 

33.0 144 4,750 

Phase I 

1-1-1-2 

2/28/98 

04:00 

32.5 143 4,650 

Phase I 

1-1-1-3 

3/1/98 

07:30 

32.6 131 4,270 

Phase I 

1-1-1-4 

3/1/98 

15:00 

35.6 130 4,630 

Phase I 

1-1-1-5 

3/1/98 

20:00 

36.7 121 4,440 

Phase I 

1-1-1-6 

3/1/98 

25:00 

35.9 116 4,160 

Phase I 

1-1-1-7 

3/1/98 

30:00 

27.6 206 5,690 

Phase I 

1-1-1-8 

3/2/98 

39:00 

26.1 192 5,010 

Phase I 

1-1-1-9 

3/2/98 

44:00 

26.8 192 5,150 

Phase I 

1-1-1-10 

3/2/98 

49:00 

26.9 184 4,950 

Phase IIa 

2a-1-1-1 

3/2/98 

54:30 

28.7 202 5,800 

Phase IIa 

2a-1-1-2 

3/3/98 

55:00 

26.3 202 5,310 

Phase IIa 

2a-1-1-3 

3/3/98 

55:30 

26.7 202 5,390 

27 
TABLE 4. XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER (SAMPLING 

LOCATION S4, MONITORING LOCATION M1)

Phase IIa 

2a-1-1-4 

3/3/98 

56:00 

27.5 200 5,500 

Phase IIa 

2a-1-1-5 

3/3/98 

56:30 

14.4 200 2,880 

Phase IIa 

2a-1-1-6 

3/3/98 

57:00 

27.3 200 5,460 

Phase IIa 

2a-1-1-7 

3/3/98 

57:30 

28.1 203 5,700 

Phase IIa 

2a-1-1-7 

3/3/98 

58:00 

28.4 202 5,740 

Phase IIa 

2a-1-1-8 

3/3/98 

58:30 

25.0 202 5,050 

Phase IIa 

2a-1-1-9 

3/3/98 

59:00 

28.1 203 5,700 

Phase IIa 

2a-1-1-10 

3/3/98 

59:30 

27.0 202 5,450 

Phase IIa 

2a-1-1-11 

3/3/98 

60:00 

27.1 203 5500 

Phase IIa 

2a-1-1-12 

3/3/98 

61:00 

28.3 204 5,770 

Phase IIa 

2a-1-1-13 

3/3/98 

62:00 

28.0 230 6,440 

Phase IIa 

2a-1-1-14 

3/3/98 

63:00 

31.0 181 5,610 

Phase II 

2-1-1-1 

3/3/98 

64:00 

64.5 209 13,500 

Phase II 

2-1-1-2 

3/3/98 

66:00 

184 211 38,800 

Phase II 

2-1-1-3 

3/3/98 

68:00 

387 209 80,900 

Phase II 

2-1-1-4 

3/3/98 

70:00 

506 214 108,000 

Phase II 

2-1-1-5 

3/3/98 

72:00 

486 226 110,000 

Phase II 

2-1-1-6 

3/3/98 

74:00 

128 227 29,000 

Phase II 

2-1-1-7 

3/3/98 

76:00 

567 223 12,700 

Phase II 

2-1-1-8 

3/3/98 

78:00 

534 224 120,000 

Phase II 

2-1-1-9 

3/4/98 

80:00 

506 217 110,000 

Phase II 

2-1-1-10 

3/4/98 

82:00 

516 219 113,000 

Phase II 

2-1-1-11 

3/4/98 

84:00 

453 219 99,200 

Phase II 

2-1-1-12 

3/4/98 

86:00 

397 217 86,100 

Phase II 

2-1-1-13 

3/4/98 

88:00 

274 214 58,600 

Phase II 

2-1-1-14 

3/4/98 

90:00 

294 219 64,400 

Phase II 

2-1-1-15 

3/4/98 

92:00 

239 216 51,600 

28 
TABLE 4. XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER (SAMPLING 

LOCATION S4, MONITORING LOCATION M1)

Phase II 

2-1-1-16 

3/4/98 

94:00 

207 215 44,500 

Phase II 

2-1-1-17 

3/4/98 

96:00 

143 220 31,500 

Phase II 

2-1-1-18 

3/4/98 

98:00 

121 218 26,400 

Phase II 

2-1-1-19 

3/4/98 

100:00 

113 216 24,400 

Phase II 

2-1-1-20 

3/4/98 

102:00 

98.0 207 20,300 

Phase II 

2-1-1-21 

3/5/98 

104:00 

95.0 218 21,400 

Phase II 

2-1-1-22 

3/3/98 

106:00 

91.1 230 21,000 

Phase II 

2-1-1-23 

3/3/98 

108:00 

85.6 181 15,500 

Phase III 

3-1-1-1 

3/5/98 

111:00 

81.0 221 17,900 

Phase III 

3-1-1-2 

3/5/98 

112:00 

70.4 221 15,600 

Phase III 

3-1-1-3 

3/5/98 

114:00 

69.5 218 15,200 

Phase III 

3-1-1-4 

3/5/98 

116:00 

64.5 218 14,100 

Phase III 

3-1-1-5 

3/5/98 

118:10 

63.3 213 13,500 

Phase III 

3-1-1-6 

3/5/98 

120:00 

59.9 213 12,800 

Phase III 

3-1-1-7 

3/5/98 

122:00 

53.3 213 11,400 

Phase III 

3-1-1-8 

3/5/98 

126:00 

49.8 212 10,600 

Phase III 

3-1-1-9 

3/6/98 

130:00 

45.5 200 9,100 

Phase III 

3-1-1-10 

3/6/98 

134:00 

44.7 200 8,940 

Phase III 

3-1-1-11 

3/6/98 

138:00 

39.6 200 7,920 

Phase III 

3-1-1-12 

3/6/98 

142:00 

39.5 194 7,660 

Notes: 

μg/L micrograms per liter 

L/h liters per hour 

μg/h micrograms per hour 

29 
Xylene Mass Removal Rates During the Demonstration 

E

xtraction W

ell S4 

0

20000400006000080000

100000120000140000

0

6.17

19.42

28.84

42.26

52.76

53.76

54.76

55.76

56.76

57.76

59.26

61.26

64.42

68.25

72.25

76.25

80.25

84.25

88.25

92.25

96.25

100.25

104.25

108.25

112.25

116.25

120.25

128.2

Ti

me in Hours 

Mass Flow Rate 

30 
This objective was to be achieved by calculating a test statistic to determine the probability of observing 

that particular result or one more extreme. However, the xylene concentrations detected during Phase I of 

the demonstration, which were expected to serve as a constant baseline for which to compare the data 

obtained during Phase II and Phase III, were decreasing throughout Phase I and were not constant to serve 

for a basis of comparison. 

Therefore, this objective, to show a statistical significance in the change of xylene concentrations in 

groundwater exiting the artificial aquifer, could not be conducted. The data obtained to achieve this 

objective are presented in Table 5. The range and average xylene concentration during each phase of the 

demonstration was as follows: 

• Phase I (steady state without surfactant addition): range of from <1 to 43.5 μg/L, with an average 

concentration of 19.8 μg/L (assuming a value equal to the detection limit for results below the 

detection limit) 

• Phase II (surfactant addition): range of from 3.8 to 12.9 μg/L, with an average concentration of 7.7 

μg/L 

• Phase III (post-surfactant addition): range of from <1 to 4.6 μg/L, with an average concentration of 

2.3 μg/L (assuming a value equal to the detection limit for results below the detection limit) 

These results show that the xylene concentration was actually decreasing in the effluent groundwater 

during the surfactant addition and post-surfactant addition phases. These results appear to reflect the 

degree of success achieved in removing the xylene mass from the artificial aquifer. With less xylene 

mass present during the surfactant addition and post-surfactant addition phases, there was apparently less 

mobilization into the groundwater flow exiting the artificial aquifer. This explanation is supported by the 

fact that the effluent xylene concentrations declined with time over both Phase II and Phase III of the 

demonstration. 

Even though a statistical test could not be calculated on the data, the data obtained during Phase II and 

Phase III does not show an upward trend. No notable increase was observed between Phase II and Phase 

III. Therefore, the hydraulic control wells appeared to have functioned as planned. 

2.3.1.3 Secondary Objective S-1 

Evaluate the acute toxicity of the treated permeate from the surfactant recovery system and of 

groundwater effluent from the artificial aquifer before and after surfactant injection. 

31 
TABLE 5. XYLENE CONCENTRATIONS IN THE EFFLUENT GROUND WATER 

(SAMPLING LOCATION S2) 

Phase Sample Time Sampling Date Total Xylene Concentration 

(μg/L) 

Phase I 

0:00 

2/28/98 <1 

Phase I 

4:00 

2/28/98 <1 

Phase I 

7:30 

3/1/98 <1 

Phase I 

15:00 

3/1/98 <1 

Phase I 

20:00 

3/1/98 39.6 

Phase I 

25:00 

3/1/98 43.5 

Phase I 

30:00 

3/1/98 39.8 

Phase I 

39:00 

3/2/98 29.9 

Phase I 

44:00 

3/2/98 24.3 

Phase I 

49:00 

3/2/98 17.7 

Phase II 

64:00 

3/3/98 12.9 

Phase II 

68:00 

3/3/98 12.9 

Phase II 

72:00 

3/3/98 11.4 

Phase II 

76:00 

3/3/98 9.7 

Phase II 

80:00 

3/4/98 9.1 

Phase II 

84:00 

3/4/98 6.3 

Phase II 

88:00 

3/4/98 5.4 

Phase II 

92:00 

3/4/98 6.7 

Phase II 

96:00 

3/4/98 5.0 

Phase II 

100:00 

3/4/98 4.6 

Phase II 

104:00 

3/5/98 3.8 

Phase II 

108:00 

3/5/98 4.6 

Phase III 

111:00 

3/5/98 4.6 

Phase III 

112:00 

3/5/98 NA 

32 
Phase III 

114:00 

3/5/98 3.5 

Phase III 

118:00 

3/5/98 3.2 

Phase III 

122:00 

3/5/98 2.6 

Phase III 

126:00 

3/5/98 2.5 

Phase III 

130:00 

3/6/98 1.2 

Phase III 

134:00 

3/6/98 1.1 

Phase III 

138:00 

3/6/98 <1 

Phase III 

142:00 

3/6/98 1.1 

Notes: 

μg/L Microgram per liter

The results of the evaluation of acute toxicity of groundwater effluent before and after surfactant injection 

are presented in Table 6. The toxicity results indicate that the extracted groundwater was not sufficiently 

toxic to kill 50 percent of the Daphnia test organisms, even at no dilution. An evaluation of the treated 

permeate was not performed since the surfactant recovery system was not operational. 

33 
TABLE 6. ACUTE TOXICITY OF GROUNDWATER EFFLUENT TO DAPHNIA

Sample Phase and Time Sampling Date Effluent Concentration for 

50% Mortality (%) 

Phase I 

00:00 

2/28/98 >100 

Phase II 

64:00 

3/3/98 >100 

Phase II 

76:00 

3/3/98 >100 

Phase II 

80:00 

3/4/98 >100 

Phase II 

104:00 

3/5/98 >100 

Phase III 

111:00 

3/5/98 >100 

Phase III 

130:00 

3/6/98 >100 

Notes: 

% Percent 

2.3.1.4 Secondary Objective S-2 

Document process operating parameters. 

Various process operating parameters were measured to document system conditions throughout the 

demonstration. Process flow rates are presented in Table 7. A summary of other process flow rates is 

given below: 

• The injected groundwater flow rate ranged from 101.4 to 112 L/h; the extracted groundwater flow 

rate ranged from 116 to 230 L/hr 

• The influent groundwater flow rate ranged from 207 to 252 L/h; the effluent groundwater flow 

rate ranged from 191 to 315 L/h. 

Additionally, selected groundwater physical and chemical characteristics (temperature, pH, conductivity 

and metals) were monitored for the influent groundwater to the artificial aquifer. The results of these 

measurements are presented in Table 8. 

34 
TABLE 7 

SURFACTANT CONCENTRATIONS 

OF GOUNDWATER INFLUENT 

Sample Description Sampling Date Anionic Surfactants 

(mg/L) 

Nonanionic 

Surfactants 

(mg/L) 

1-4-X-1 

2/28/98 <0.05 <0.25 

2-4-X-1 

3/3/98 <0.05 <0.25 

2-4-X-3 

3/3/98 <0.05 <0.25 

2-4-X-4 

3/3/98 <0.05 <0.25 

2-4-X-6 

3/4/98 <0.05 <0.25 

2-4-X-7 

3/4/98 <0.05 <0.25 

2-4-X-9 

3/4/98 <0.05 <0.25 

2-4-X-11 

3/5/98 <0.05 <0.25 

3-4-X-3 

3/5/98 <0.05 <0.25 

3-4-X-5 

3/5/98 <0.05 <0.25 

3-4-X-8 

3/6/98 <0.05 <0.25 

3-4-X-10 

3/6/98 <0.05 <0.25 

• Note: Acute toxicity values expressed in the mortality of species for each tested; 

Fish, Daphnia, and Leuchtbakterien repectively. 

35 
TABLE 8. SELECTED PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE INFLUENT GROUNDWA

Sample Description: Sample Date: 

Phase I 

Groundwater 

Effluent 

(S2) 

03/01/98 

Phase I 

Injected 

Groundwater 

(S3) 

03/01/98 

Phase II 

Injected 

Groundwater 

(S3) 

03/04/98 

Phase II 

Injected into 

Hydraulic Control 

Wells (S6) 

03/04/98 

Phase III 

Injected 

Groundwater 

(S3) 

03/05/98 

Temperature ( C) 18.5 18.5 19.1 19.1 18.6 pH 7.53 7.53 7.9 7.9 7.83 Surfactants, anionic (mg/L) 

<0.05 <0.05 <0.05 <0.05 <0.05 

Surfactants, nonionic (mg/L) 

<0.25 <0.25 <0.25 <0.25 0.27 

Metals Al (μg/L) 45 <40 <40 65 <40 Sb (μg/L) <30 <30 <30 <30 <30 As (μg/L) <50 <50 <50 <50 <50 Ba (μg/L) 172 83 159 64 143 Be (μg/L) <1 <1 <1 <1 <1 Cd (μg/L) <4 <4 <4 <4 <4 Cr (μg/L) <10 <10 <10 <10 <10 Co (μg/L) <10 <10 <10 <10 <10 Cu (μg/L) 11 <10 <10 <10 <10 Fe (μg/L) 484 <10 851 <10 864 Pb (μg/L) <40 <40 <40 <40 <40 Li (μg/L) <5 <5 7 <5 7 

36 
TABLE 8. SELECTED PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE INFLUENT GROUNDWA

Sample Description: Sample Date: 

Phase I 

Groundwater 

Effluent 

(S2) 

03/01/98 

Phase I 

Injected 

Groundwater 

(S3) 

03/01/98 

Phase II 

Injected 

Groundwater 

(S3) 

03/04/98 

Phase II 

Injected into 

Hydraulic Control 

Wells (S6) 

03/04/98 

Phase III 

Injected 

Groundwater 

(S3) 

03/05/98 

Mn (μg/L) 849 7 676 <5 552 Mo (μg/L) <10 <10 <10 <10 17 Ni (μg/L) 15 <15 <15 <15 <15 Se (μg/L) <80 <80 <80 <80 <80 Ag (μg/L) <10 <10 <10 <10 <10 Sr (μg/L) 541 465 514 419 504 TI (μg/L) <40 <40 <40 <40 <40 V (μg/L) <10 <10 <10 <10 <10 Zn (μg/L) 15 370 5 2 <2 Na (mg/L) 153 154 151 115 155 K (mg/L) 12.5 12.4 12.7 9.1 12.2 Mg (mg/L) 8.9 8.5 8.4 7.2 8.5 Ca (mg/L) 97.1 84.2 95.5 73.0 92.0 Ammonia (mg/L) <0.02 0.10 0.26 <0.02 0.15 F (mg/L) 0.18 0.17 0.18 0.15 0.18 Cl (mg/L) 264 262 263 186 257 NO2 (mg/L) <0.02 1.2 <0.02 <0.02 <0.02 NO3 (mg/L) 0.3 1.2 <0.3 0.5 <0.3 HCO3 (mg/L) 210 177 197 177 195 

37 
Sample Description: 

Sample Date: 

Phase I 

Groundwater 

Effluent 

(S2) 

03/01/98 

Phase I 

Injected 

Groundwater 

(S3) 

03/01/98 

Phase II 

Injected 

Groundwater 

(S3) 

03/04/98 

Phase II 

Injected into 

Hydraulic Control 

Wells (S6) 

03/04/98 

Phase III 

Injected 

Groundwater 

(S3) 

03/05/98 

SO4 (mg/L) 94 85 93 66 89 

Notes: 

C Degrees Celsius mg/L Milligrams per liter μg/L Micrograms per liter 

38 
As shown in Table 8, the influent groundwater was relatively consistent in its physical and chemical 

characteristics. Specifically, the groundwater influent temperature ranged from 18.5 C to 19.1 C and the 

pH ranged from 7.53 to 7.9. Major cations and anions also showed little variability. 

2.3.1.5 Secondary Objective S-3 

Document the xylene and surfactant concentrations in the treated surfactant recovery permeate and 

surfactant concentration in effluent groundwater. 

The results of the surfactant concentration measurements for samples of the groundwater effluent are 

presented in Table 9. As shown in this table, neither anionic nor nonionic surfactants were detected in 

any of the groundwater effluent samples. Thus, the injection of groundwater into the hydraulic control 

wells appears to have been successful in excluding surfactant from the groundwater effluent. 

Results were not available for the treated permeate since the surfactant recovery system was not 

operational during the demonstration. 

2.3.1.6 Secondary Objective S-4 

Estimate capital and operating costs. 

Because the surfactant recovery system was not operational during the demonstration and the ability to 

recycle surfactant was not determined, a detailed cost analysis of the surfactant-enhanced extraction 

technology could not be developed. The cost of the surfactant provided by BASF was 3.50 DM per 

kilogram of surfactant ($1.82 per kilogram assuming a 1.92 DM to $1 U.S. exchange rate). A further 

discussion of cost information is provided in Section 3.0. 

39 
TABLE 9. SURFACTANT CONCENTRATIONS IN GROUNDWATER EFFLUENT 

(SAMPLE LOCATION S2)

Sample Phase and Time Sampling Date Anionic Surfactants 

(mg/L) 

Nonanionic 

Surfactants 

(mg/L) 

Phase I 

00:00 

2/28/98 <0.05 <0.25 

Phase II 

64:00 

3/3/98 <0.05 <0.25 

Phase II 

72:00 

3/3/98 <0.05 <0.25 

Phase II 

76:00 

3/3/98 <0.05 <0.25 

Phase II 

84:00 

3/4/98 <0.05 <0.25 

Phase II 

88:00 

3/4/98 <0.05 <0.25 

Phase II 

96:00 

3/4/98 <0.05 <0.25 

Phase II 

104:00 

3/5/98 <0.05 <0.25 

Phase III 

114:00 

3/5/98 <0.05 <0.25 

Phase III 

122:00 

3/5/98 <0.05 <0.25 

Phase III 

134:00 

3/6/98 <0.05 <0.25 

Phase III 

142:00 

3/6/98 <0.05 <0.25

 Notes: 

mg/L Milligram per liter 

< Less than 

40 
2.3.2 Data Quality 

This section summarizes the results for quality control samples collected and analyzed during the 

demonstration and addresses associated data quality issues. The results of this assessment were used to 

produce the known, defensible information employed to define the investigation findings and to draw 

conclusions. 

The primary QC samples processed in relation to the sole critical analysis (xylene in groundwater 

samples) included trip blanks and field blanks, matrix spike/matrix spike duplicates (MS/MSDs). Xylene 

concentrations reported in previous sections for evaluation of process performance are total xylenes 

concentrations, measured as the sum of ortho-xylene (o-xylene) and combined meta-xylene and paraxylene (m/p-xylene). For the quality control samples, o-xylene and m/p-xylene are reported separately. 

Field blanks and trip blanks were collected to monitor whether field techniques or sample shipping 

potentially introduced xylene into the field samples. All three trip blanks and all three field blanks had 

concentrations of <1 μg/L for both o-xylene and m/p-xylene. Therefore, field techniques and sample 

shipping did not introduce measurable concentrations of xylenes. 

One extracted groundwater MS/MSD sample was analyzed in association with each of the sampling 

events to assess the precision and accuracy of the xylene results in the groundwater matrix. Table 10 lists 

the results of these MS/MSD analyses. In general, these results were within the acceptance criteria for 

recovery of xylene and relative percent difference (RPD) of the duplicate results. Specifically, only three 

recoveries out of 22 pairs of MS/MSD sample results were outside of the acceptance criteria for the 

associated percent recoveries. Of those three samples, two samples were also outside of the RPD 

acceptance criteria. Further, none of the excursions outside of the acceptance criteria were extraordinary 

or appeared to indicate anything other than random errors. Therefore, these MS/MSD results indicate that 

generally acceptable laboratory precision and accuracy were achieved for the xylene determinations in 

groundwater samples. 

41 
TABLE 10. RESULTS FOR MATRIX SPIKE QC SAMPLES

Sample 

Phase, Time 

Parameter Sample 

(μg/L) 

MS 

(μg/L) 

MSD 

(μg/L) 

Spike 

(μg/L) 

Spike 

Recovery 

RPD 

(%) 

QC 

(%

Phase I, 08:00 m/p-xylene <1 55.16 56.42 50.8 108.1 2.3 75

o-xylene <1 27.1 26.56 24.4 110.7 2.0 75

Phase II, 88:00 m/p-xylene 1.6 25.1 24.78 25.44 97.4 1.3 75

o-xylene <1 12.02 11.78 12.2 97.7 2.0 75

Phase III, 112:00 m/p-xylene <1 49.84 50.42 50.88 97.9 1.2 75

o-xylene <1 24.3 24.18 24.4 99.4 0.5 75

Phase III, 122:00 m/p-xylene <1 26.06 25.16 25.44 102.3 3.5 75

o-xylene <1 12.58 11.92 12.2 103.0 5.4 75

Phase I, 15:00 m/p-xylene 3.4 42.66 49.86 50.88 82.5 15.6 75

o-xylene 1.5 23.38 24.74 24.4 94.6 5.7 75

Phase II, 80:00 m/p-xylene 29.2 58.3 55.12 50.88 103.1 5.6 75

o-xylene 16.4 27.9 26.94 24.4 100.9 3.5 75

Phase III, 114:00 m/p-xylene 10.1 78.6 53.3 50.88 150.5† 38.4 75

o-xylene 7.6 38.74 25.78 24.44 152.6† 40.2 75

Phase I, 15:00 m/p-xylene 5.5 54.78 55.92 50.88 104.2 1.1 75

o-xylene 2.6 26.76 26.82 24.4 107.5 0.2 75

Phase II, 72:00 m/p-xylene 2.2 53.46 54.06 50.88 104.2 1.1 75

42 
TABLE 10. RESULTS FOR MATRIX SPIKE QC SAMPLES

o-xylene 0.2 25.2 25.9 24.4 107.5 0.2 7

Phase III, 118:00 m/p-xylene 0.9 49.46 53.3 50.88 96.9 7.5 7

o-xylene 0.4 24.3 25.78 24.4 103.1 2.8 7

Phase I, 7:30 m/p-xylene 13.4 15.38 15.66 12.72 99.8 5.9 7

o-xylene 2.9 5.94 6.04 6.1 88.0 1.8 7

Phase I, 39:00 m/p-xylene 10.8 11.86 11.8 12.72 76.3 0.5 7

o-xylene 2.2 5.0 5.22 6.1 74.6 4.5 7

Phase I, 44:00 m/p-xylene 11.1 26.1 27.06 25.44 93.8 3.6 7

o-xylene 2.4 12.48 13.26 12.2 98.4 6.1 7

Phase II, 60:00 m/p-xylene 238.2 69.62 68.75 25.44 86.4 1.3 7

o-xylene 45.1 22.02 21.96 12.2 106.6 0.3 7

Phase II, 76:00 m/p-xylene 123.9 46.24 45.06 25.44 84.3 2.6 7

o-xylene 23.6 17.08 16.56 12.2 121.9 2.9 7

Phase II, 78:00 m/p-xylene 16.0 33.68 32.98 25.44 119.9 2.1 7

o-xylene 3.1 15.5 15.06 12.2 121.9 2.9 7

Phase II, 94:00 m/p-xylene 44.0 39.1 35.9 25.44 119.9 8.6 7

o-xylene 9.3 17.24 15.92 12.2 126.1† 7.9 7

Phase II, 102:00 m/p-xylene 9.6 25.78 24.98 25.44 93.8 3.3 7

o-xylene 1.7 12.36 12.44 12.2 98.4 0.8 7

Phase II, 94:00 m/p-xylene 18.3 26.6 26.78 25.44 90.2 0.7 7

o-xylene 3.7 12.82 13.02 12.2 98.9 1.5 7

Phase III, 122:00 m/p-xylene 10.2 27.78 25.62 25.44 101.1 8.1 7

43 
TABLE 10. RESULTS FOR MATRIX SPIKE QC SAMPLES

o-xylene 2.0 13.5 13.28 12.2 107.3 1.7 7

Phase III, m/p-xylene 20.6 27.72 27.46 25.44 92.88 0.9 7

o-xylene 4.3 12.88 12.54 12.2 98.4 2.6 7

 Notes: † and bold font indicates QC results outside of acceptancea criteria (75-125% recovery and/or <20%RPD). 

44 
2.3.3 Conclusions 

The results of the surfactant-enhanced extraction bilateral SITE demonstration are discussed above in 

relation to the two primary and four secondary objectives. The corresponding conclusions of this 

evaluation are summarized below: 

• The xylene mass removal rate increased as a result of surfactant injection. The concentration of 

xylene in the extracted groundwater increased by a factor of approximately 15 after the injection 

of the surfactant solution. The graph of the xylene mass removal rate (Figure 9) illustrates the 

increase in xylene mass removal rate after injection of the surfactant. 

• There was no significant increase in xylene concentration exiting the artificial aquifer due to 

surfactant enhancement. Groundwater effluent xylene concentrations during: Phase I (steady 

state without surfactants) ranged from <1 to 43.5 μg/L with an average concentration of 19.8

μg/L; Phase II (non steady state with surfactants) ranged from 3.8 to 12.9 μg/L with an average 

concentration of 7.7 μg/L; and Phase III (steady state, post surfactant injection) ranged from <1 to 

4.6 μg/L with an average concentration of 2.3 μg/L. 

• The toxicity results indicate that the extracted groundwater was not sufficiently toxic to kill 50 

percent of the Daphnia test organisms, even at no dilution. 

• The process operation parameters were as follows. The extracted groundwater flow rates ranged 

from 116 to 230 L/h and injected groundwater (M2) flow rates ranged from 101.4 to 112 L/h. 

The influent groundwater (M3) flow rate ranged from 207 to 252 L/h and the effluent 

groundwater (Location M4) flow rate ranged from 191 to 315 L/h. The following changes were 

made to the planned operation: 1) A revised flow scheme was utilized and Wells MW 1, 2, and 4 

were not used; a new well (MW 6) was installed and utilized as the groundwater/surfactant 

injection well, 2) The above ground surfactant recovery system was not operational. The 

groundwater influent samples temperature ranged from 18.5 to 19.1 C; and pH ranged from 7.53 

to 7.9. 

• The surfactant concentrations in the effluent groundwater were all less than 0.05 mg/L for anionic 

surfactants and less than 0.25 mg/L for nonanionic surfactants. The treated permeate was not 

analyzed since the recovery system was not operational. 

• The cost of the surfactant provided by BASF was 1.78 Euros (€) per kilogram of surfactant 

($2.33 per kilogram assuming a 0.76 € to $1 U.S. exchange rate). Because the surfactant 

recovery system was not operational during the demonstration and the ability to recycle the 

surfactant was not determined, a detailed cost analysis could not be developed. 

45 
3.0 ECONOMIC ANALYSIS 

This section presents available cost information for the surfactant-enhanced extraction technology based 

on data provided by Tauw Umwelt GmbH Moers and BASF AG. 

Because the surfactant recovery system was not operational during the demonstration and the ability to 

recycle surfactant was not determined, a detailed cost analysis of the surfactant-enhanced extraction 

technology could not be developed. 

Cost information was solicited from Tauw Umwelt GmbH Moers and BASF AG. The only cost 

information provided was that provided by BASF AG for the surfactant. BASF indicated that the cost of 

the surfactant was 1.78 Euros (€) per kilogram of surfactant ($2.33 per kilogram assuming a 0.76 € to $1 

U.S. exchange rate). 

Although treatment costs were not independently estimated, the following cost categories (Evans 1990) 

should be considered when evaluating the potential cost of treating groundwater using the surfactantenhanced extraction technology: 

• Site preparation 

• Permitting and regulatory requirements 

• Capital equipment 

• Startup 

• Labor 

• Consumables and supplies 

• Utilities 

• Effluent treatment and disposal 

• Residuals and waste shipping and handling 

• Analytical services 

• Maintenance and modifications 

• Demobilization 

46 
4.0 TECHNOLOGY APPLICATIONS ANALYSIS 

This section evaluates the general applicability of the surfactant-enhanced extraction technology to 

remediation of the saturated zone at contaminated sites. Information presented in this section is intended 

to assist decision makers in screening specific technologies for a particular cleanup situation. This section 

presents the advantages, disadvantages, and limitations of the technology and discusses factors that have a 

major impact on the performance and cost of the technology. The analysis is based both on the 

demonstration results and on available information from other applications of the technology. 

4.1 FEASIBILITY STUDY EVALUATION CRITERIA 

This section assesses the surfactant-enhanced extraction technology against the nine evaluation criteria 

used for conducting detailed analyses of remedial alternatives in feasibility studies under CERCLA (EPA 

1988). 

4.1.1 Overall Protection of Human Health and the Environment 

The surfactant-enhanced extraction technology provides both short-term and long-term protection of 

human health and the environment by removing organic contaminants from the saturated zone. Treated 

groundwater is recycled to the aquifer, thereby limiting exposure routes. Exposure from air emissions can 

be minimized by passing the system's air process stream through carbon adsorption units before discharge 

to the atmosphere. 

4.1.2 Compliance with ARARs 

Although general and specific applicable or relevant and appropriate requirements (ARARs) were not 

specifically identified for the surfactant-enhanced extraction technology, compliance with chemical-, 

location-, and action-specific ARARs should be determined on a site-specific basis. While location- and 

action-specific ARARs generally can be met, compliance with chemical-specific ARARs depends on the 

efficiency of the surfactant-enhanced extraction system in removing contaminants from the groundwater 

and the site-specific cleanup level. 

47
4.1.3 Long-Term Effectiveness and Permanence 

The surfactant-enhanced extraction system permanently removes organic contaminants from the saturated 

zone and recovers the surfactant for reuse. Long-term risks to treatment system workers, the community, 

and the environment from exposure to contaminated groundwater are mitigated by ensuring that 

established standards are met. 

The concentrated solution of organic contaminants (the permeate) must be disposed of properly to ensure 

the permanence of remediation using this technology. Secondary emissions from the treatment and 

disposal of the permeate may present other risks not addressed in this report. 

4.1.4 Reduction of Toxicity, Mobility, or Volume Through Treatment 

As discussed in Section 4.1.1 and 4.1.3, the surfactant-enhanced extraction technology offers permanent 

removal of organic contaminants from the saturated zone. As such, the toxicity, mobility, and volume of 

contaminants are also significantly reduced. 

4.1.5 Short-Term Effectiveness 

The removal of organic contaminants is achieved relatively quickly, providing for short-term 

effectiveness as well as long-term effectiveness, as discussed in Section 4.1.3. Potential short-term risks 

presented during system operation to workers, the community, and the environment includes air 

emissions. Exposure to air emissions during operation, monitoring, and maintenance can be minimized 

through the removal of contaminants from the system's air process stream using carbon adsorption units 

before emitting this stream to the atmosphere. 

4.1.6 Implementability 

The surfactant-enhanced extraction technology has been demonstrated at a number of sites in the U.S. and 

in Europe. While an innovative technology, sufficient technical information is available to support 

application of this technology (Ground Water Remediation Technologies Analysis Center, Technology 

Evaluation Report: Surfactants/Cosolvents). The equipment and supply requirements for surfactant 

extraction are relatively standard, including wells, pumps, piping, and chemicals (surfactant). Surfactant 

separation and recovery processes are more complex, and need to be further proven prior to full-scale 

implementation. 

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4.1.7 Cost 

The cost of surfactant-enhanced extraction has not been fully defined due to unresolved issues related to 

recycling the surfactant. However, currently available information suggest that the cost will be relatively 

high in comparison to other technologies. Thus, surfactant enhanced extraction should be reserved for 

contaminated sites where other, less expensive treatment technologies cannot accomplish the remediation 

goals. 

4.1.8 State Acceptance 

State acceptance is anticipated because the surfactant-enhanced extraction system uses widely accepted 

processes to remove contaminants from the saturated zone, and air emissions can be effectively treated 

using carbon adsorption. If remediation is conducted as part of Resource Conservation and Recovery Act 

(RCRA) corrective actions, state regulatory agencies will require that permits be obtained before 

implementing the system, such as a permit to operate the treatment system and an air emissions permit. 

4.1.9 Community Acceptance 

The system's size and space requirements, as well as the principles of operation, may raise concern in 

nearby communities. However, proper management and operational controls coupled with minimal shortterm risks to the community and the permanent removal of contaminants in situ make this technology 

likely to be accepted by the public. 

4.2 APPLICABLE WASTES 

The surfactant-enhanced extraction technology demonstrated at Stuttgart-Vaihingen, Germany, was 

designed to remove xylene from the saturated zone. The developer claims and other demonstration 

results suggest that the technology can also remove other non-aqueous phase liquid organic contaminants. 

However, the technology’s applicability to contaminants other than xylene was not examined as part of 

this demonstration. 

4.3 LIMITATIONS OF THE TECHNOLOGY 

The developer claims that there are no concentration limits on the contamination that can be treated by the 

system. However, high concentrations of contaminants may require longer operation of the technology 

and multiple extractions to achieve remediation goals. 

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5.0 SURFACTANT-ENHANCED EXTRACTION TECHNOLOGY STATUS 

According to Tauw Umwelt GmbH Moers, the technology can be used for remediation of contamination 

in the saturated zone with both VOCs and semivolatile organic compounds (SVOCs). The surfactantenhanced extraction technology has been or is currently being demonstrated at several sites in the U.S. 

There are currently no commercially operating systems in the U.S. 

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6.0 REFERENCES 

American Public Health Association (APHA), American Water Works Association (AWWA), and Water 

Environment Federation (WEF). 1994. Standard Methods for the Examination of Water and 

Wastewater. Greenberg, Arnold E., Lenore S. Clesceri, and Andrew D. Eaton, eds. 19th edition. 

Washington, D.C. 

Evans, G. 1990. "Estimating Innovative Technology Costs for the SITE Program." Journal of Air and 

Waste Management Assessment. Volume 40, Number 7. July. 

Ground Water Remediation Technologies Analysis Center (GWRTAC). Technology Evaluation Report: 

Surfactants/Cosolvents. 

Tetra Tech EM Inc. (TTEMI) 1998 Quality Assurance Project Plan for the Surfactant-Enhanced 

Extraction Technology Evaluation in Stuttgart, Germany. February 4. 

U.S. Environmental Protection Agency (EPA). 1983. Methods for Chemical Analysis of Water and 

Wastes (MCAWW). Environmental Monitoring and Support Laboratory. Cincinnati, Ohio. EPA600/4-79-020. March 

EPA. 1988. "Guidance for Conducting Remedial Investigations and Feasibility Studies under 

CERCLA." EPA/540/G-89/004. October. 

EPA. 1996. “Test Methods for Evaluating Solid Waste.” Volumes 1A through 1C. SW-846. Third 

Edition. Update III. Office of Solid Waste and Emergency Response (OSWER). Washington, DC. 

December. 

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