vvEPA 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 -20 mg/1 Xylene Settling Tank stlonWell Air Stripper 1 \ \ \ V / ~ / / \ \ \ \ \ \ \ x Air (ram VEGAS-Hall . Liquid (Water) Streams _ Air Streams ------- EPA/540/R-07/004 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 ------- 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. ------- 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 in ------- CONTENTS NOTICE ii 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. 2.3. 2.3. 2.3. 2.3. 2.3. .1 Primary Objective P-l 26 .2 Primary Objective P-2 27 .3 Secondary Objective S-l 31 .4 Secondary Objective S-2 34 .5 Secondary Objective S-3 39 .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 ------- 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 MAS S 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 Ml) 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 °C 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. (ig/L Micrograms per liter VISITT Vendor Information System for Innovative Treatment Technologies VEGAS Versuchseinrichtung zur Grundwasser-und Altlastensanierung VOC Volatile organic compound vn ------- To Convert Centimeters Centimeters Cubic meters Cubic meters Cubic meters Degrees Celsius Hectopascals Kilograms per square meter Kilograms Kilograms per liter Kilometers Liters Liters per hour Liters per second Meters Millimeters Square meters CONVERSION TABLE (Metric to English Units) Into Feet Inches Cubic feet Gallons Cubic yards Degrees Fahrenheit Atmosphere Pounds per square inch, absolute Pounds Pounds per cubic foot Miles (statute) Gallons Gallons per minute Cubic feet (standard) per minute 2.12 Feet Inches Square feet Multiply By 0.0328 0.393 35.0 264 1.31 multiply by 1.80; add 32 0.000986 0.00142 2.21 12.8 0.621 0.265 0.0044 3.278 0.039 10.764 Vlll ------- 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 ((ig/L) before surfactant injection, 7.7 (ig/L during surfactant injection, and 2.3 (ig/L following surfactant injection. • The toxicity results indicate that the extracted groundwater was not sufficiently toxic to kill 50 percent of the Daphniatest 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 101.4to 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 surfactant- enhanced 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. ------- Location of VEGAS Research Facility Figure 1 Location of the VEGAS Research Facility ------- 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 ------- 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 decision- making • 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. ------- 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 full- scale 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 focon- Probiotec technical consulting partnership is not directly involved in the German remedial actions, and ------- 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 pilot- scale 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. ------- BMBF PROJECT MANAGER Dr. Hartmut Pohl UBA [TECHNICAL COORDINATOR Dr. Annett Weiland-Wascher I VEGAS PROJECT MANAGER Mr. Reinhold Josef ARGE FOCON-PROBIOTECl PROJECT MANAGER Mr. Burkhard Heuel-Fabianekl BASFAG PROJECT MANAGER Dr. Michael Ehle IINSTITUTFRESNIUS PROJECT MANAGER Dr. Reiner Kurz INSTITUTFRESNIUS QA MANAGER Dr. Jurgen Ehmann EPA PROGRAM MANAGER Annette Gatchett EPA QA COORDINATOR Ann Vega EPA PROJECT MANAGER Dr. Ronald Lewis TETRA TECH QA MANAGER Dr. Greg Swanson TETRA TECH PROJECT MANAGER Roger Argus Tetra Tech Technical Support Staff Figure 2 Project Organization ------- 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 11/6857023 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 (CLU- IN) electronic bulletin board contains information on the status of SITE technology evaluations. Its web site is www.clu-in.org. ------- Technical reports may be obtained by contacting the Center for Environmental Research Information (CERI), 26 West Martin Luther King Drive in Cincinnati, Ohio 45268 at (513) 569-7562. Additional information is available on the EPA home page at: www.epa. gov/oerrpage/superfund/sites. ------- 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. 10 ------- Direction of Groundwater Flow Medium Sand Coarse Sand Injected Xylene Medium Sand Length in Meters E o Groundwater Elevation Medium Grained Sand Coarse Grained Sand Fine Grained Sand Contamination Plume Figure 3 Cross-Section of Artificial Aquifer ------- "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 ------- 6.0 m Length in Meters -9.0 rrr Direction of Groundwater Flow MW5 MW1 MW2 Injected Groundwater/ Surfactant Solution Influent ^ Groundwater Effluent Groundwater Top View of Artificial Aquifer Side View of Artificial Aquifer Medium Grained Sand Fine Grained Sand Coarse Grained Sand ^ Groundwater Elevation Figure 4 Monitoring Well Configuration ------- Groundwater Influent Conventional Groundwater Surfactant Solution Direction of Groundwater Flow MW4 VEGAS-Container 1 MW5 MW1 ^/1W2 Tauw Surfactant Recovery System 1 i Permeate Discharge Air Treatment Groundwater Effluent Source: ArGe focon PROBIOTEC, 1997 Figure 5 Surfactant Injection/Extraction System ------- • 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 15 ------- Extraction Water Flow Rate = 200 l/h -20 mg/l Xylene Settling Tank Extraction Well Air Stripper r\ Air from VEGAS -Hall Recycle to Hydraulic Control Wells Liquid (Water) Streams Air Streams Sewage Drain Concentrate Figure 6 Surfactant Recovery System ------- 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 PI. 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. 17 ------- 128 64 Contaminant Mass Removal Rate (9/hr) Initial Surfactant Injection Days Figure 7 Conceptual Plot of Anticipated Xylene Mass Removal Rates ------- TABLE 2. NONCRITICAL MEASUREMENT PARAMETERS Secondary Objective Measurement Parameter SI. 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 LC50 SW-846 VEGAS U.S. Environmental Protection Agency Lethal concentration - 50 percent Test Methods for Evaluating Solid Waste 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 SI: 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 Ml: 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) 20 ------- Groundwater Influent Conventional Groundwater Treatment Direction of Groundwater Flow MW4 MW6 MW1 MW3 VEGAS-Container MW5 MW2 Granular Activated Carbon Bed Groundwater Effluent Discharge Diagram 1: Simplified Process Flow Diagram for Phase 1 Conventional Groundwater Treatment Groundwater Influent (IJI Activated Carbon Filter Surfactants Direction of Groundwater Flow MW4 MW3 VEGAS-Container MW 1 t MW5 MW2 Extracted Solution Storage Tank Groundwater Effluent Diagram 2: Simplified Process Flow Diagram for Phases 2 and 3 Legend ^S1) Sampling location (Ml) Monitoring location Source: ArGefocon PROBIOTEC, 1997 Figure 8 Sampling and Monitoring Locations ------- 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 SW-846 8260B EPA/600/4-90/027 SW-846 3010A/6010A MCAWW 170.1 SW-846 9040B SW-846 9050 SM 5540C and D Parametera VOCs Acute toxicity VIetals Temperature Name of Method VOCs by GC/MS: Capillary Column Technique (preparation method is included in 8260B) 48-hour Static Acute Toxicity Test (Definitive) Using Ceriodaphnia dubia (C. dubia) Acid digestion of Aqueous Samples/Inductively coupled Plasma- Atomic Emission Spectroscopy Temperature )H pH Electrometric Measurement Conductivity [Specific Conductance 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 Ha, 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 mid- morning 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-l 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 Ml. 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 Ml) Sample Description Phase I 1-1-1-1 Phase I 1-1-1-2 Phase I 1-1-1-3 Phase I 1-1-1-4 Phase I 1-1-1-5 Phase I 1-1-1-6 Phase I 1-1-1-7 Phase I 1-1-1-8 Phase I 1-1-1-9 Phase I 1-1-1-10 Phase Ha 2a-l-l-l Phase Ha 2a-l-l-2 Phase Ha 2a-l-l-3 Sampling Date and Time 2/28/98 00:00 2/28/98 04:00 3/1/98 07:30 3/1/98 15:00 3/1/98 20:00 3/1/98 25:00 3/1/98 30:00 3/2/98 39:00 3/2/98 44:00 3/2/98 49:00 3/2/98 54:30 3/3/98 55:00 3/3/98 55:30 Total Xylene Concentration (HS/L) 33.0 32.5 32.6 35.6 36.7 35.9 27.6 26.1 26.8 26.9 28.7 26.3 26.7 Flow Rate (L/h) 144 143 131 130 121 116 206 192 192 184 202 202 202 Xylene Mass Removal Rate (Hg/h) 4,750 4,650 4,270 4,630 4,440 4,160 5,690 5,010 5,150 4,950 5,800 5,310 5,390 27 ------- TABLE 4. XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER (SAMPLING LOCATION S4, MONITORING LOCATION Ml) Phase Ha 2a-l-l-4 Phase Ha 2a-l-l-5 Phase Ha 2a-l-l-6 Phase Ha 2a-l-l-7 Phase Ha 2a-l-l-7 Phase Ha 2a-l-l-8 Phase Ha 2a-l-l-9 Phase Ha 2a-l-l-10 Phase Ha 2a-l-l-ll Phase Ha 2a-l-l-12 Phase Ha 2a-l-l-13 Phase Ha 2a-l-l-14 Phase II 2-1-1-1 Phase II 2-1-1-2 Phase II 2-1-1-3 Phase II 2-1-1-4 Phase II 2-1-1-5 Phase II 2-1-1-6 Phase II 2-1-1-7 Phase II 2-1-1-8 Phase II 2-1-1-9 Phase II 2-1-1-10 Phase II 2-1-1-11 Phase II 2-1-1-12 Phase II 2-1-1-13 Phase II 2-1-1-14 Phase II 2-1-1-15 3/3/98 56:00 3/3/98 56:30 3/3/98 57:00 3/3/98 57:30 3/3/98 58:00 3/3/98 58:30 3/3/98 59:00 3/3/98 59:30 3/3/98 60:00 3/3/98 61:00 3/3/98 62:00 3/3/98 63:00 3/3/98 64:00 3/3/98 66:00 3/3/98 68:00 3/3/98 70:00 3/3/98 72:00 3/3/98 74:00 3/3/98 76:00 3/3/98 78:00 3/4/98 80:00 3/4/98 82:00 3/4/98 84:00 3/4/98 86:00 3/4/98 88:00 3/4/98 90:00 3/4/98 92:00 27.5 14.4 27.3 28.1 28.4 25.0 28.1 27.0 27.1 28.3 28.0 31.0 64.5 184 387 506 486 128 567 534 506 516 453 397 274 294 239 200 200 200 203 202 202 203 202 203 204 230 181 209 211 209 214 226 227 223 224 217 219 219 217 214 219 216 5,500 2,880 5,460 5,700 5,740 5,050 5,700 5,450 5500 5,770 6,440 5,610 13,500 38,800 80,900 108,000 110,000 29,000 12,700 120,000 110,000 113,000 99,200 86,100 58,600 64,400 51,600 28 ------- TABLE 4. XYLENE EXTRACTION RATES IN THE EXTRACTED GROUNDWATER (SAMPLING LOCATION S4, MONITORING LOCATION Ml) Phase II 2-1-1-16 Phase II 2-1-1-17 Phase II 2-1-1-18 Phase II 2-1-1-19 Phase II 2-1-1-20 Phase II 2-1-1-21 Phase II 2-1-1-22 Phase II 2-1-1-23 Phase III 3-1-1-1 Phase III 3-1-1-2 Phase III 3-1-1-3 Phase III 3-1-1-4 Phase III 3-1-1-5 Phase III 3-1-1-6 Phase III 3-1-1-7 Phase III 3-1-1-8 Phase III 3-1-1-9 Phase III 3-1-1-10 Phase III 3-1-1-11 Phase III 3-1-1-12 3/4/98 94:00 3/4/98 96:00 3/4/98 98:00 3/4/98 100:00 3/4/98 102:00 3/5/98 104:00 3/3/98 106:00 3/3/98 108:00 3/5/98 111:00 3/5/98 112:00 3/5/98 114:00 3/5/98 116:00 3/5/98 118:10 3/5/98 120:00 3/5/98 122:00 3/5/98 126:00 3/6/98 130:00 3/6/98 134:00 3/6/98 138:00 3/6/98 142:00 207 143 121 113 98.0 95.0 91.1 85.6 81.0 70.4 69.5 64.5 63.3 59.9 53.3 49.8 45.5 44.7 39.6 39.5 215 220 218 216 207 218 230 181 221 221 218 218 213 213 213 212 200 200 200 194 44,500 31,500 26,400 24,400 20,300 21,400 21,000 15,500 17,900 15,600 15,200 14,100 13,500 12,800 11,400 10,600 9,100 8,940 7,920 7,660 Notes: ug/L micrograms per liter L/h liters per hour ug/h micrograms per hour 29 ------- Xylene Mass Removal Rates During the Demonstration Extraction Well S4 140000 -r 120000 -- 100000 -- •S 80000 - 60000 40000 -- 20000 -- Time in Hours Figure 9 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 (ig/L, with an average concentration of 19.8 (ig/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 (ig/L, with an average concentration of 7.7 • Phase III (post-surfactant addition): range of from <1 to 4.6 (ig/L, with an average concentration of 2.3 (ig/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-l 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 Phase I 0:00 Phase I 4:00 Phase I 7:30 Phase I 15:00 Phase I 20:00 Phase I 25:00 Phase I 30:00 Phase I 39:00 Phase I 44:00 Phase I 49:00 Phase II 64:00 Phase II 68:00 Phase II 72:00 Phase II 76:00 Phase II 80:00 Phase II 84:00 Phase II 88:00 Phase II 92:00 Phase II 96:00 Phase II 100:00 Phase II 104:00 Phase II 108:00 Phase III 111:00 Phase III 112:00 Sampling Date 2/28/98 2/28/98 3/1/98 3/1/98 3/1/98 3/1/98 3/1/98 3/2/98 3/2/98 3/2/98 3/3/98 3/3/98 3/3/98 3/3/98 3/4/98 3/4/98 3/4/98 3/4/98 3/4/98 3/4/98 3/5/98 3/5/98 3/5/98 3/5/98 Total Xylene Concentration (HS/L) <1 <1 <1 <1 39.6 43.5 39.8 29.9 24.3 17.7 12.9 12.9 11.4 9.7 9.1 6.3 5.4 6.7 5.0 4.6 3.8 4.6 4.6 NA 32 ------- Phase III 114:00 Phase III 118:00 Phase III 122:00 Phase III 126:00 Phase III 130:00 Phase III 134:00 Phase III 138:00 Phase III 142:00 3/5/98 3/5/98 3/5/98 3/5/98 3/6/98 3/6/98 3/6/98 3/6/98 3.5 3.2 2.6 2.5 1.2 1.1 <1 1.1 Notes: Hg/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 Phase I 00:00 Phase II 64:00 Phase II 76:00 Phase II 80:00 Phase II 104:00 Phase III 111:00 Phase III 130:00 Sampling Date 2/28/98 3/3/98 3/3/98 3/4/98 3/5/98 3/5/98 3/6/98 Effluent Concentration for 50% Mortality (%) >100 >100 >100 >100 >100 >100 >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 1-4-X-l 2-4-X-l 2-4-X-3 2-4-X-4 2-4-X-6 2-4-X-7 2-4-X-9 2-4-X-l 1 3-4-X-3 3-4-X-5 3-4-X-8 3-4-X-10 Sampling Date 2/28/98 3/3/98 3/3/98 3/3/98 3/4/98 3/4/98 3/4/98 3/5/98 3/5/98 3/5/98 3/6/98 3/6/98 Anionic Surfactants (mg/L) <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.05 Nonanionic Surfactants (mg/L) <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 <0.25 • Note: Acute toxicity values expressed in the mortality of species for each tested; Fish, Daphnia, and Leuchtbakterien repectively. ------- TABLE 8. SELECTED PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE INFLUENT GROUNDWATER Sample Description: Sample Date: Temperature ( C) pH Surfactants, anionic (mg/L) Surfactants, nonionic (mg/L) Phase I Groundwater Effluent (S2) 03/01/98 18.5 7.53 <0.05 <0.25 Phase I Injected Groundwater (S3) 03/01/98 18.5 7.53 <0.05 <0.25 Phase II Injected Groundwater (S3) 03/04/98 19.1 7.9 <0.05 <0.25 Phase II Injected into Hydraulic Control Wells (S6) 03/04/98 19.1 7.9 <0.05 <0.25 Phase III Injected Groundwater (S3) 03/05/98 18.6 7.83 <0.05 0.27 Phase III Groundwater Injected into Hydraulic Control Wells (S6) 03/05/98 18.6 7.83 <0.05 <0.25 Metals Al (ug/L) Sb (ug/L) As (ug/L) Ba (ug/L) Be (ug/L) Cd (ug/L) Cr(ug/L) Co (ug/L) Cu (ug/L) Fe (ug/L) Pb (ug/L) Li (ug/L) 45 <30 <50 172 <1 <4 <10 <10 11 484 <40 <5 <40 <30 <50 83 <1 <4 <10 <10 <10 <10 <40 <5 <40 <30 <50 159 <1 <4 <10 <10 <10 851 <40 7 65 <30 <50 64 <1 <4 <10 <10 <10 <10 <40 <5 <40 <30 <50 143 <1 <4 <10 <10 <10 864 <40 7 <40 <30 <50 66 <1 <4 <10 <10 <10 <10 <40 5 36 ------- TABLE 8. SELECTED PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE INFLUENT GROUNDWATER (Continued) Sample Description: Sample Date: Mn (ng/L) Mo (jig/L) Ni (ng/L) Se (ng/L) Ag (ng/L) Sr (,ig/L) TI (ng/L) V (ng/L) Zn(ng/L) Na (mg/L) K (mg/L) Mg (mg/L) Ca (mg/L) Ammonia (mg/L) F (mg/L) Cl (mg/L) NO2 (mg/L) NO3 (mg/L) HCO3 (mg/L) Phase I Groundwater Effluent (S2) 03/01/98 849 <10 15 <80 <10 541 <40 <10 15 153 12.5 8.9 97.1 <0.02 0.18 264 0.02 0.3 210 Phase I Injected Groundwater (S3) 03/01/98 7 <10 <15 <80 <10 465 <40 <10 370 154 12.4 8.5 84.2 0.10 0.17 262 1.2 1.2 177 Phase II Injected Groundwater (S3) 03/04/98 676 <10 <15 <80 <10 514 <40 <10 5 151 12.7 8.4 95.5 0.26 0.18 263 0.02 O.3 197 Phase II Injected into Hydraulic Control Wells (S6) 03/04/98 <5 <10 <15 <80 <10 419 <40 <10 2 115 9.1 7.2 73.0 O.02 0.15 186 0.02 0.5 177 Phase III Injected Groundwater (S3) 03/05/98 552 17 <15 <80 <10 504 <40 <10 <2 155 12.2 8.5 92.0 0.15 0.18 257 0.02 O.3 195 Phase III Groundwater Injected into Hydraulic Control Wells (S6) 03/05/98 <2 <10 <15 <80 <10 423 <40 <10 7 112 9.7 7.6 75.0 O.02 0.16 187 0.02 0.7 176 37 ------- Sample Description: Sample Date: SO4 (mg/L) Phase I Groundwater Effluent (S2) 03/01/98 94 Phase I Injected Groundwater (S3) 03/01/98 85 Phase II Injected Groundwater (S3) 03/04/98 93 Phase II Injected into Hydraulic Control Wells (S6) 03/04/98 66 Phase III Injected Groundwater (S3) 03/05/98 89 Phase III Groundwater Injected into Hydraulic Control Wells (S6) 03/05/98 68 Notes: C mg/L Hg/L Degrees Celsius Milligrams per liter 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 Cto 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 GROUND WATER EFFLUENT (SAMPLE LOCATION S2) Sample Phase and Time Phase I 00:00 Phase II 64:00 Phase II 72:00 Phase II 76:00 Phase II 84:00 Phase II 88:00 Phase II 96:00 Phase II 104:00 Phase III 114:00 Phase III 122:00 Phase III 134:00 Phase III 142:00 Sampling Date 2/28/98 3/3/98 3/3/98 3/3/98 3/4/98 3/4/98 3/4/98 3/5/98 3/5/98 3/5/98 3/6/98 3/6/98 Anionic Surfactants (mg/L) 0.05 <0.05 0.05 0.05 O.05 0.05 O.05 O.05 0.05 O.05 O.05 0.05 Nonanionic Surfactants (mg/L) 0.25 O.25 0.25 0.25 O.25 0.25 O.25 O.25 0.25 O.25 O.25 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 para- xylene (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 (ig/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 Phase I, 08:00 Phase II, 88:00 Phase III, 112:00 Phase III, 122:00 Phase I, 15:00 Phase II, 80:00 Phase III, 114:00 Phase I, 15:00 Phase II, 72: 00 Parameter m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene Sample (HS/L) <1 <1 1.6 <1 <1 <1 <1 <1 3.4 1.5 29.2 16.4 10.1 7.6 5.5 2.6 2.2 MS (HS/L) 55.16 27.1 25.1 12.02 49.84 24.3 26.06 12.58 42.66 23.38 58.3 27.9 78.6 38.74 54.78 26.76 53.46 MSD (HS/L) 56.42 26.56 24.78 11.78 50.42 24.18 25.16 11.92 49.86 24.74 55.12 26.94 53.3 25.78 55.92 26.82 54.06 Spike (HS/L) 50.8 24.4 25.44 12.2 50.88 24.4 25.44 12.2 50.88 24.4 50.88 24.4 50.88 24.44 50.88 24.4 50.88 Spike Recovery 108.1 110.7 97.4 97.7 97.9 99.4 102.3 103.0 82.5 94.6 103.1 100.9 150.5* 152.6* 104.2 107.5 104.2 RPD (%) 2.3 2.0 1.3 2.0 1.2 0.5 3.5 5.4 15.6 5.7 5.6 3.5 38.4 40.2 1.1 0.2 1.1 QC limits (%R) 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 QCRPD (%) <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 42 ------- TABLE 10. RESULTS FOR MATRIX SPIKE QC SAMPLES Phase III, 118:00 Phase I, 7: 30 Phase I, 39:00 Phase I, 44:00 Phase II, 60:00 Phase II, 76:00 Phase II, 78:00 Phase II, 94:00 Phase II, 102:00 Phase II, 94:00 Phase III, 122:00 o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene o-xylene m/p-xylene 0.2 0.9 0.4 13.4 2.9 10.8 2.2 11.1 2.4 238.2 45.1 123.9 23.6 16.0 3.1 44.0 9.3 9.6 1.7 18.3 3.7 10.2 25.2 49.46 24.3 15.38 5.94 11.86 5.0 26.1 12.48 69.62 22.02 46.24 17.08 33.68 15.5 39.1 17.24 25.78 12.36 26.6 12.82 27.78 25.9 53.3 25.78 15.66 6.04 11.8 5.22 27.06 13.26 68.75 21.96 45.06 16.56 32.98 15.06 35.9 15.92 24.98 12.44 26.78 13.02 25.62 24.4 50.88 24.4 12.72 6.1 12.72 6.1 25.44 12.2 25.44 12.2 25.44 12.2 25.44 12.2 25.44 12.2 25.44 12.2 25.44 12.2 25.44 107.5 96.9 103.1 99.8 88.0 76.3 74.6 93.8 98.4 86.4 106.6 84.3 121.9 119.9 121.9 119.9 126. lf 93.8 98.4 90.2 98.9 101.1 0.2 7.5 2.8 5.9 1.8 0.5 4.5 3.6 6.1 1.3 0.3 2.6 2.9 2.1 2.9 8.6 7.9 3.3 0.8 0.7 1.5 8.1 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 75-125 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 43 ------- TABLE 10. RESULTS FOR MATRIX SPIKE QC SAMPLES Phase III, o-xylene m/p-xylene o-xylene 2.0 20.6 4.3 13.5 27.72 12.88 13.28 27.46 12.54 12.2 25.44 12.2 107.3 92.88 98.4 1.7 0.9 2.6 75-125 75-125 75-125 <20 <20 <20 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 (ig/L with an average concentration of 19.8 (ig/L; Phase II (non steady state with surfactants) ranged from 3.8 to 12.9 (ig/L with an average concentration of 7.7 (ig/L; and Phase III (steady state, post surfactant injection) ranged from <1 to 4.6 (ig/L with an average concentration of 2.3 (ig/L. • The toxicity results indicate that the extracted groundwater was not sufficiently toxic to kill 50 percent of the Daphniatest 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 surfactant- enhanced 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. 48 ------- 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 short- term 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. 49 ------- 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 surfactant- enhanced 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. 50 ------- 6.0 REFERENCES American Public Health Association (APHA), American Waterworks 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, B.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. EPA- 600/4-79-020. 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. 51 ------- |