SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
IN SITU FLUSHING ACTION TEAM MEETING

Sheraton Grand Hotel
Irving, Texas
September 14-15, 1998

WELCOME AND OPENING REMARKS
Dr. A. Lynn Wood, U.S. Environmental Protection Agency (EPA)
Mr. Stephen Shoemaker, E.I. DuPont DeNemours & Company, Inc.

Dr. A. Lynn Wood and Mr. Stephen Shoemaker, the two co-chairs for the Remediation Technologies Development Forum (RTDF) In Situ Flushing Action Team, opened the meeting by welcoming participants (see Attachment A) to the team's third official meeting. Mr. Shoemaker explained that the RTDF was established so that members of government, industry, and academia could work together to solve difficult environmental remediation issues. He said that several RTDF Action Teams have been established, each of which focuses on a different innovative technology.

Mr. Shoemaker said the In Situ Flushing Action Team's mission is to facilitate the development and implementation of in situ flushing technology for site remediation. To date, Mr. Shoemaker noted, the Team has focused on remediation of nonaqueous phase liquids (NAPL), but the focus could be expanded in the future. Although the mission sounds simple, Mr. Shoemaker said, several technical problems must be addressed to meet the Team's objectives. During the January 1998 meeting, four subgroups were identified to address these issues.

The co-chairs noted three goals for this September 1998 meeting:

• Allow the four subgroups to reconvene. Mr. Shoemaker said the principal reason for holding this meeting was to allow subgroups to met separately and carry forth with the momentum that was evident at the January 1998 meeting. One participant asked Mr. Shoemaker whether the subgroups were supposed to meet a goal by the end of the meeting (e.g.., start drafting a document). Mr. Shoemaker said each subgroup is at a different stage of progress. Eventually, he said, the goal is to generate a series of joint working documents. For this meeting, however, no definite goals were expected to be achieved.
• Provide requested information. During the January 1998 meeting, several participants asked for information about activities conducted by the Interstate Technology Regulatory Cooperation (ITRC) and the RTDF Bioremediation Consortium. Interest in the latter, Mr.. Shoemaker noted, was spurred by suggestions of linking in situ flushing and bioremediation technologies together in a treatment train. In response to RTDF member requests, Mr. Shoemaker continued, representatives from ITRC and the Bioremediation Consortium were invited to speak at this meeting.
• Provide site updates. Dr. Wood said site updates would be presented to keep RTDF members abreast of upcoming and new projects.

DESCRIPTION OF SUBGROUPS

After completing his introductory remarks, Mr. Shoemaker invited subgroup leaders to summarize their activities to date. Mr. Shoemaker informed participants that they would be participating in separate subgroup breakout meetings after hearing the descriptions.

Endpoint Assessment/Technical Performance Criteria
Dr. George Losonsky, IT Corporation

Dr. George Losonsky provided a brief summary of the Endpoint Assessment/Technical Performance Subgroup's activities. He said three objectives were identified during the January 1998 meeting:

• Develop guidelines for establishing target endpoints for in situ flushing technologies. Dr. Losonsky said regulators, consultants, and industry members are all asking for information on target endpoints. As a result, the Subgroup plans to evaluate the whole spectrum of possible target endpoints (e.g., achieving maximum concentration levels [MCLs] or removing a specified percentage of NAPL).
• Develop protocol/guidelines for predicting the ability to (1) reach target endpoints and (2) identify potential negative outcomes. Dr. Losonsky said his Subgroup plans to produce a tool that state regulators and consultants can use to quickly determine whether in situ flushing technologies will be successful at a certain site.
• Develop a framework for performance assessment. Dr. Losonsky said his Subgroup plans to identify the performance measurements that all in situ flushing investigators should be evaluating. He said the Subgroup will need to work with the Technical Practices/Protocol Subgroup to accomplish this goal.

Economic Assessment and Remedial Agent Recovery/Reuse
Dr. Jeff Harwell, University of Oklahoma

Dr. Jeff Harwell provided a brief summary of the Economic Assessment and Remedial Agent Recovery/ Reuse Subgroup's activities. He said his Subgroup has decided to concentrate their efforts on (1) determining the best way to perform an economic analysis for in situ flushing technologies and (2) comparing costs against those generated by other types of technologies. Dr. Harwell said four goals were identified during the January 1998 meeting:

• Identify ways to recover and reuse surfactants. Dr. Harwell said the Subgroup plans to discuss limitations of different surfactant recovery technologies. At this point, he stressed, the Subgroup does not plan to evaluate cosolvent recovery technologies because no proponents of the technology are currently involved in the Subgroup.
• Review and compare existing economic analyses. Dr. Harwell noted that a wide range of cost estimates have been cited for in situ flushing technologies. He said his Subgroup will review existing analyses and identify the underlying assumptions. Doing so, he continued, should provide insight as to why estimates in the literature vary so dramatically.
• Determine the best way to present "bottom-line" cost.
• Work with state regulators on addressing reinjection policy issues.

Full-Scale Design
Dr. Michael Annable, University of Florida

Dr. Michael Annable provided a brief summary of the Full-Scale Design Subgroup's activities. He said that the Subgroup identified two goals at the January 1998 RTDF meeting:

• Develop a hypothetical full-scale in situ flushing design that could serve as a model for others to use. Dr. Annable said his Subgroup plans to place a full-scale design model on the RTDF Web site and to establish linkages to ongoing full-scale flushing projects. At the last RTDF meeting, Dr. Annable noted, the Subgroup had discussed using the Advanced Applied Technology Demonstration Facility (AATDF)'s full-scale design manual as a springboard for the RTDF full-scale model. Since that time, however, Dr. Annable has discovered that AATDF plans to publish their information as a monograph. Thus, while the RTDF will be able to refer to the AATDF manual, they will not be able to utilize it as they had hoped.
• Identify an ongoing full-scale design project and provide as sistance. Dr. Annable said the Subgroup plans to assist groups who are conducting a full-scale flushing project by (1) taking an advisory role, and (2) helping to distribute project information via the RTDF Web site. The latter, Dr. Annable noted, is particularly important.

Dr. Annable said that his Subgroup and the Technical Practices/Protocol Subgroup share many of the same goals. For this reason, he said, there has been some discussion of combining these Subgroups.

Technical Practices/Protocol
Dr. Gary Pope, University of Texas

Dr. Gary Pope provided a brief summary of the Technical Practices/Protocol Subgroup's activities. During the January 1998 meeting, Dr. Pope reported, the Subgroup decided to create a living up-to-date technical guide that would describe best practices and technology needs. The group had decided, Dr. Pope continued, to separate their technical guide into two volumes, with the first addressing "What we know now" and the second addressing "What we still need to do." Dr. Pope said the Subgroup had decided to focus only on surfactant and cosolvent flushing technologies. He did note, however, that the focus could expand if proponents of other flushing agents joined the Subgroup. Dr. Pope displayed the outlines that were generated at the January 1998 meeting:

Volume I. Protocol

1.0	Description of Technology
1.1	Screening
	1.1.1	Site Parameters
	1.1.2	Preliminary Cost Estimating/Budgeting
1.2	Conceptual Approach (e.g., phased site characterization, phased surfactant/cosolvent flushing events)
1.3	Site Characterization
1.4	Design Processes
	1.4.1	Laboratory Testing
	1.4.2	Subsurface Modeling
	1.4.3	Facilities Design (e.g., well construction and placement)
	1.4.4	Treatment Engineering
1.5	Performance Assessment
1.6	Implementation/Regulatory Issues (e.g., injection well permitting/regulatory issues with disposal)
Volume II. Technology Needs
1.0	State of the Art
1.1	Technology Limitations (e.g., fractured bedrock)
1.2	Site Characterization (e.g., innovative dense nonaqueous phase liquids [DNAPL] detection technologies)
1.3	Design Processes
	1.3.1	Heterogeneities
	1.3.2	Access Limitations (e.g., buildings)
	1.3.3	Surfactant Recovery
	1.3.4	Integration with Other Technologies in a Treatment Train
	1.3.5	Application to Other Compounds (e.g., polychlorinated biphenyls [PCBs])
	1.3.6	Numerical Modeling
1.4	Recommendations

Like Dr. Annable, Dr. Pope agreed that a significant overlap exists between the Full-Scale Design and the Technical Practices/Protocol Subgroups. He agreed the two Subgroups should meet and discuss the most effective way to accomplish their goals without duplicating each other's efforts. He expressed a strong need to expand the participation base for his Subgroup.

SUBGROUP REPORTS

After the Subgroup leaders described their activities, the participants separated into their four Subgroups and discussed goals and strategies for the remainder of the afternoon (September 14). The following day (September 15), the entire team reconvened and Subgroup leaders summarized the discussions from their breakout meetings.

Dr. Wood noted that there would likely be significant overlap between the Subgroups. He said the RTDF team would need to identify more ways for Subgroup members to communicate with each other between meetings. He encouraged participants to offer communication suggestions.

Endpoint Assessment/Technical Performance Criteria

Subgroup Leader:	George Losonsky, IT Corporation Randy Parker, EPA
Other Participants:	Neeraj Gupta, Battelle Memorial Institute Min Quan Jin, Duke Engineering & Services Bill Kosko, Tetra Tech EM, Inc. Ken Moor, Idaho National Engineering & Environmental Laboratory (INEEL) Stephen Shoemaker, DuPont Richard Willey, EPA

Dr. Losonsky said his Subgroup defined three tasks (Tasks I, II, and III) during their breakout meetings and made progress on the first two. Participants who concentrated their efforts on Task I included Dr. Losonsky, Randy Parker, Richard Willey, and Ken Moor. Those who concentrated on Task II included Neeraj Gupta, Min-Quan Jin, Bill Kosco, and Stephen Shoemaker.

Task I: Write a Letter

Dr. Losonsky said the Subgroup agreed to write a letter requesting regulatory guidance in defining target endpoints for in situ flushing technologies. Once the letter is completed, Dr. Losonsky noted, the Subgroup plans to have it reviewed internally by the RTDF and then by the Technology Innovation Office (TIO)'s Richard Steimle. After reviews are completed, the letter will be distributed to Walter Kovalick (TIO), Robert Olexsey (Office of Research and Development), and Steve Luftig (Office of Emergency and Remedial Response). Dr. Losonsky said the Subgroup also hopes to publish the letter on the RTDF Web site and as an open letter to a journal.

Dr. Losonsky said that the letter will contain the following sections:

• Statement of the problem/background
• Approaches to defining target endpoints other than using MCLs
• Recommendations of the most useful and meaningful target endpoints to use for in situ flushing technologies
• Closing summary and a date by which the RTDF would like a response

Dr. Losonsky said the Subgroup started drafting the letter during their breakout meetings and he read what they had generated. Dr. Losonsky stressed that the letter is a work in progress and many elements remain to be added. He said the final letter will clearly define what the RTDF is and will address the following issues: (1) risk-based decision making over short- and long-terms, (2) the intrinsic value of ground water as a resource, (3) economic feasibility, and (4) long-term survival of potentially responsible parties (PRPs). In addition, the authors plan to offer their assistance in defining endpoints by providing technical support.

In general, the draft letter was well received by the RTDF audience. Dr. Harwell suggested changing the statement "Remove DNAPL to within 10% of the original mass" so that the letter does not imply that 90% mass removal is the best that in situ flushing technologies can achieve. He stressed that this technology will likely remove much more than that, perhaps even 99%. One meeting participant asked whether the Subgroup could predict how regulatory agencies would respond to the letter. Mr. Willey said that the Subgroup really has no idea. He said that the group feels it is necessary to ask regulatory agencies about target endpoints, even though they are not necessarily expecting a clear-cut answer. Mr. Willey stressed that defining appropriate endpoints is an issue that the entire nation is wrestling with.

Task II: Make a List Of Performance Assessment Parameters That Should Be Monitored Before, During, and After In Situ Flushing

Dr. Losonsky said the Subgroup compiled a list of performance parameters. For each parameter, Dr. Losonsky continued, the Subgroup identified measurement tools, error bars, and their utility. He said the group separated the parameters into three categories: hydrogeological, geochemical, and microbiological. A table was generated listing all of the identified parameters. The table is presented below and indicates:

• When data should be collected (i.e, before [B], during [D] or after [A] an in situ flush).
• How important it is to collect data. Gupta said that primary parameters are those that must be collected to determine the success of an in situ flush. Those listed as secondary parameters, Gupta continued, are not necessarily essential for measuring success, but do still provide important information.
• Why the parameter data are useful. The table indicates whether the parameters are used as design parameters (DP), process control (PC), site characterization (SC), compliance monitoring (CM), or success measure (SM).
• Which matrix is tested.

Dr. Losonsky said the table will be placed on the Internet and he encouraged RTDF members to review and comment.

TABLE 1: PERFORMANCE ASSESSMENT PARAMETERS

Parameter	When should data be collected (in relation to the flush)?	Rank (Importance in defining performance)	Why should the data be collected?	Matrix
Hydrogeological Parameters
Hydraulic conductivity (vertical conductivity [Kv] and horizontal conductivity [Kh])	B,A	Primary	DP,SC	soil
Porosity and grain size distribution	B	Primary	DP,SC	soil
Water levels (Vertical and horizontal gradients)	B,D,A	Primary	PC,SC,CM	water
Water and NAPL saturation	B,A	Primary	DP,SC,SM	soil
Flow rates	D	Primary	PC	water
Fluid density	B	Primary	DP,SC	NAPL
Viscosity	B	Primary	DP,SC	NAPL
Interfacial tension	B	Primary	DP,SC	NAPL
DNAPL entry pressure (capillary desaturation curve)	B	Primary	DP,SC	soil,water
Surfactant Phase Behavior	B,D,A	Primary	DP,CM	water
Geochemical Parameters
Soil concentration	B,A	Primary	SC,DP,SM	soil
pH	B,D,A	Secondary	SC,PC,DP	water
Eh (ORP)	B,D,A	Secondary	SC,PC,DP	water
Specific conductance	B,D,A	Primary	SC,PC,DP	water
Temperature	B,D,A	Primary	SC,PC,DP	water
Adsorption coefficient	B	Primary	DP,SC	soil
Major Ions (cations [Ca, Mg, Na, K, Fe] and anions [SO4-, HCO3-, Cl-, CO3-, NO3-])	B,D,A	Primary, Secondary	SC,DP	water
TOC	B,A	Secondary	SC,SM	water,soil
Total petroleum hydrocarbon (TPH)	B,A	Secondary	SC,CM	water,soil
CEC	B	Primary	SC,DP	soil
Ground-water concentration	B,D,A	Primary	SC,PC,SM,CM	water
Surf Rc	B,D,A	Primary	PC,SM,CM	water
C. Tracer	D	Secondary	PC,CM	water
Microbiological Parameters
DNAPL degradation daughter products	B,A	Secondary	SC	water
Dissolved oxygen	B,A	Secondary	SC	water
Carbon dioxide	B,A	Secondary	SC	water
BOD/COD	B,A	Secondary	SC	water
Fe2, Fe3	B,A	Secondary	SC	water

Dr. Losonsky noted that the Subgroup plans to construct parameter response curves in the future.

Task III

Dr. Losonsky said the Subgroup was unable to tackle Task III during the breakout meetings. As part of this task, the Subgroup plans to:

• Review the experience base
• Evaluate the accuracy, precision, and limitations of assessment tools
• Evaluate coupled predictive models (e.g., multiphase flow and natural attenuation)

Economic Assessment and Remedial Agent Recovery/Reuse

Subgroup Leader:	Jeff Harwell, University of Oklahoma
Other Participants:	Steve Byrne, Cytec Industries Fred Holzmer, Duke Engineering & Services, Inc. Robert Jones, The Lubrizol Corporation Robert Legrand, Radian International Wayne Lundberg, U.S. Air Force (USAF) Steve Rosansky, Battelle Stephen Schmelling, EPA Leland Vane, EPA

Dr. Harwell said his Subgroup talked about a variety of contaminant removal technologies and surfactant reconcentration technologies during their breakout meetings. He said the group compiled a list of technologies (see Table 2) and discussed their status and cost. Dr. Harwell said the list would be distributed to all RTDF members and that Leland Vane would field any comments that members might have on the list.

TABLE 2: SURFACTANT RECOVERY AND REUSE TECHNOLOGIES

Contaminant Removal Technologies	Surfactant Reconcentration Technologies
1. Air stripper 2. Liquid/liquid extraction, with or without membrane 3. Pervaporation 4. Steam strip 5. Vacuum extraction 6. Precipitation 7. Carbon adsorption 8. Catalytic degradation 9. Other phase separations 10. Distillation (separate contaminant from volatile cosolvent)	1. Micellar-enhanced ultrafiltration (MEUF) 2. Foam fraction - Mining industry type fractionation - Tray strippers - Air sparged hydrocyclone 3. Nanofiltration 4. Distillation 5. Precipitation 6. Batch drying

Dr. Harwell said three concerns were identified during the discussion of different technologies: (1) mineral precipitation, (2) identifying the best method for off-gas treatment, and (3) the ramifications of using alcohols as a flushing agent. Dr. Harwell said the Subgroup failed to identify suitable technologies for alcohol recovery. Also, he noted, treating waste alcohol can be very expensive. For these reasons, the Subgroup recommended finding ways to conduct floods without involving alcohol. (Note: See discussion below on "Sage's Dry Cleaners" for a discussion of a system that was used to recover alcohol.)

Dr. Harwell said the Subgroup evaluated existing economic analyses and identified their underlying assumptions. He said many available and pending economic analyses overestimate costs because they fail to account for:

• Recovering and reusing surfactants. Dr. Harwell noted that costs can be cut drastically when surfactants are recovered and reinjected into the ground.
• Using an incremental approach. During the January 1998 meeting, the Subgroup demonstrated that a site can be remediated at a lower cost if it is divided into small segments, with each segment treated one at a time. With this approach, investigators only purchase enough surfactant, recovery equipment, and NAPL disposal equipment to treat small areas. Then, after one segment area is treated, the equipment is withdrawn, "walked" over to the next downstream segment, and reinstalled. Dr. Harwell said the Subgroup members agreed that this incremental approach should be employed at all sites. Dr. Harwell predicted that cost savings could be maximized by separating a site into 8 to 10 segments. He stressed, however, that additional research is required before firm recommendations can be offered about the optimal number of segments per site.
• Using skid-mounted units and temporary piping. Dr. Harwell noted that pump and treat technologies require permanent, and therefore expensive, installations. He said all available in situ flushing cost analyses assume that the equipment used will be of the same caliber as that used in the pump and treat system. Dr. Harwell questioned this logic, noting that permanent structures should not be required because in situ flushing projects should be completed within 2 to 3 years of initiation. Using skid-mounted units and temporary piping, installation costs would be about 20 to 30% of that reported for pump and treat technologies. One participant pointed out that using temporary equipment will not save long-term costs if pump and treat systems are required as a follow-up to in situ flushing technologies. Dr. Harwell agreed, but said that the Subgroup assumed in situ flushing technologies would only be installed at sites where no more than 2 to 3 years of follow-up pump and treat technology would be required.

Dr. Harwell said the Subgroup performed a quick "back-of-the-envelope" analysis to get an idea how much it would cost to remove 99.9% of NAPL if surfactants were recovered and reused, the incremental method were employed, and temporary equipment were purchased. Preliminary estimates indicate that the cost would be about $20 to $30 per cubic yard. Dr. Harwell says this rough estimate agrees with some of the estimates that Mark Hasegawa has generated for other projects..

Dr. Harwell said the Subgroup plans to redo some of the cost analyses that are currently available. Mark Hasegawa agreed to provide some worksheets to help facilitate this process. Also, the Subgroup has decided to conduct their own cost analysis for a hypothetical full-scale design. They would like to coordinate with the Full-Scale Design Subgroup on this aspect of the project. Ideally, Dr. Harwell said, the Subgroup plans to meet in person at least once before the next RTDF team meeting is scheduled.

Dr. Harwell said the team briefly discussed reinjection policy issues and the importance of surveying state regulators about their opinions regarding reinjection. Dr. Harwell said he would like Kathleen Yager and the ITRC to work together on this task.

Technical Practices/Protocol and Full-Scale Design Subgroups

Subgroup Leader:

Gary Pope, University of Texas Michael Annable, University of Florida

Other Participants:

Thomas Early, Oak Ridge National Laboratory Jennifer Field, Oregon State University Mark Hasegawa, Surbec Environmental C. Wayne Ives, New Hampshire Department of Environmental Services Richard Jahnke, Lubrizol Corporation John Londergan, Duke Engineering & Services, Inc. Clarence Miller, Rice University Kurt Pennell, Georgia Institute of Technology Jeffrey Sacre, Ground Water Remediation Technologies Analysis Center (GWRTAC) Thomas Sawyer, Oregon State University Mike Shook, INEEL Henry Stopplecamp, Burlington Northern Sante Fe Kevin Warner, Levine*Fricke*Recon A. Lynn Wood, EPA S. Laura Yeh, Naval Facilities Engineering Service Center (NFESC)

Dr. Annable provided an update of the Technical Practices/Protocol and Full-Scale Design Subgroups' breakout meetings. He said that the two Subgroups had officially decided to combine. Dr. Annable said that the two Subgroups shared the same common goal of producing text to discuss processes and steps involved with design. In addition to this goal, the Full Scale Design Subgroup had planned to distribute information about ongoing design projects via the Internet. Annable said this goal would not be lost by combining the groups.

Technical Guide: Volume I

Dr. Annable noted that the Technical Practice/Protocols Subgroup's original outline for Volume I was changed quite a bit during the breakout meeting. Some topics were reordered or expanded, and some new topics (e.g., full-scale design, pilot scale studies, and a general evaluation step) were added. In summary, Volume I will contain eight sections: (1) Screening, (2) Conceptual Approach, (3) Site Characterization, (4) General Evaluation Step, (5) Design Processes, (6) Pilot-Scale Testing, (7) Performance Assessment, and (8) Full-Scale Design. Attachment B provides a much more detailed outline and indicates which Subgroup members have agreed to work on different topics. RTDF meeting participants generally accepted the revised Volume I outline. Laura Yeh recommended, however, adding information regarding surfactant recovery and reuse, the incremental method, and waste management costs in the full-scale design section. Dr. Annable said the Volume I outline will be refined over the next weeks and months. He agreed to send all RTDF members a copy of the refined outline.

Technical Guide: Volume II

Dr. Annable noted that Clarence Miller, Thomas Early, Jeff Sacre, and John Londergan have agreed to lead the effort to develop Volume II of the technical guide. This small team plans to build on GWRTAC's information base. Ideally, Dr. Annable noted, this team plans to distribute information on a few ongoing full-scale projects in "real-time" fashion over the Internet.

REPORT FROM THE RTDF BIOREMEDIATION CONSORTIUM

Dr. David Ellis, DuPont Specialty Chemicals

Dr. David Ellis provided a brief overview of the RTDF Bioremediation Consortium's history and organizational structure, activities at Dover air force base (AFB), and future areas of research. In addition, Dr. Ellis speculated on interactions between surfactant flushing and natural attenuation.

Bioremediation Consortium's History and Organizational Structure

Dr. Ellis said the Bioremediation Consortium's mission is to accelerate the development of the most cost-effective in situ bioremediation processes for degrading chlorinated solvents. To accomplish this mission, Dr. Ellis continued, Consortium members are undertaking the research, development, demonstration, and evaluation effort that is needed to achieve public and regulatory acceptance of these technologies.

Dr. Ellis said the Consortium consists of seven industrial companies (i.e., Beak International, Ciba-Geigy Corporation, Dow Chemical Company, DuPont, General Electric, ICI Americas, Novartis, and Zeneca, Inc.) and three government agencies (i.e., the Air Force, EPA, and the Department of Energy [DOE]). Several other organizations support the Bioremediation Consortium's activities, but do not have voting members on the Consortium's steering committee. These include, the Western Governors Association (WGA), the ITRC, United States Geological Survey (USGS), and the Chlorine Chemistry Council (CCC). Dr. Ellis said that the Consortium's organizational structure is bound by research contracts and Cooperative Research and Development Agreements (CRADAs). Dr. Ellis noted that the Consortium generates much of its own funding. (In fact, industrial members are required to contribute a minimum of cash or in-kind services.) Funding for Consortium projects is also provided by CCC and site owners.

Dr. Ellis said the Consortium has six demonstration projects underway, two of which involve natural attenuation. To date, Dr. Ellis noted, the Consortium has focused primarily on the remediation of trichloroethylene (TCE) and its biodegradation products. In the near future, however, the Consortium will be expanding their focus to evaluate other chlorinated contaminants.

Evidence of Natural Attenuation at Dover AFB

Dr. Ellis said that Dover AFB was the first site where the Consortium evaluated natural attenuation. At this site, Dr. Ellis said, the Consortium had two objectives:

• Apply and understand the development and application of a conceptual model.
• Examine the three lines of evidence that are defined in the National Research Council's report on natural attenuation:

• Are concentrations downgradient of the source lower than what you would expect from chemical and mechanical effects?

• Has biodegradation been observed in field studies?

• Is there laboratory evidence demonstrating that microbial organisms are capable of degrading chlorinated wastes?

Dr. Ellis said that the plume at Dover is large (7,000 feet long and 3,000 feet wide) and occupies the lower zone (the bottom 10 to 15 feet) of a layered aquifer. Originally, Dr. Ellis noted, the Consortium believed that the chlorinated solvents were all part of one plume. Now, however, they realize that the plume is separated into two subplumes, which run parallel to each other. After studying the plume for three years, the Consortium found that the plume is atypical, demonstrating high concentration streaks down the middle.

Dr. Ellis reported that contaminant concentrations have dropped markedly over the last five years. For example, TCE concentrations have dropped from 50 to 60 parts per million (ppm) to 3 to 4 ppm. Likewise, cis-dichloroethene (cis-DCE) concentrations have decreased from 12 ppm to 7 ppm. Also, vinyl chloride concentrations have decreased from 1 ppm to 0.4 ppm. Dr. Ellis said the disappearance of these constituents is credited, in large part, to two biodegradative processes:

• Reductive dehalogenation. Dr. Ellis said reductive dehalogenation processes convert tetrachloroethylene (PCE) to TCE, then to cis-DCE, then to vinyl chloride, then to ethene (non-toxic). Dr. Ellis said this pathway is important at Dover AFB, but that other biological pathways probably contributed more heavily to the biological destruction of chlorinated wastes.
• Oxidation. Dr. Ellis said that bacteria use cis-DCE, vinyl chloride, and ethene as a food source. The bacteria, he continued, can convert these compounds to carbon dioxide when in the presence of oxygen (direct oxidation) or oxygen plus methane (co-oxidation). Dr. Ellis said that proof of these conversions is provided by radiolabeled tests. Dr. Ellis said that oxidative reactions occur in zones where mixing processes lead to oxygenation of ground water. Dr. Ellis said the Consortium learned much about oxidative processes while at Dover AFB. Before working at this site, they had been unaware that bacteria could so effectively oxidize cis-DCE and vinyl chloride.

Dr. Ellis said other biological processes (e.g., fermentation) may play a role in biodegradation. No proof is available to confirm this, however. Dr. Ellis also offered the following points about the Dover AFB plume:

• The plume is static and has not traveled during the 5 years that the Consortium has been studying it.
• Retardation is low for all compounds.
• Contaminant distributions were not observed as expected (e.g.., the vinyl chloride plume has not traveled beyond the TCE plume).
• The half-lives observed are similar to those cited in literature..
• The geochemistry at Dover AFB is very favorable.
• Chloride concentrations accumulated as solvents disappeared.
• Microcosm studies show clear biodegradation.

Evaluation of Mass Flux at Dover AFB

Dr. Ellis said the Consortium evaluated mass flux of chlorocarbons at Dover AFB. This topic, he stressed, has generated much interest in the scientific community. He noted that Dover AFB has an excellent network of wells. In the past, a skilled geologist calculated mass flux (in pounds per year) using the well data. Dr. Ellis noted that this approach was inexpensive ($10,000 to $15,000) because it simply involved using a static test pump and an existing well network. The Consortium decided to calculate mass flux using a much more complicated methodology that employed field transect studies. With this approach, conceptual lines were drawn across the plume and chemical and hydrogeological data were collected at numerous points along the transect lines. Dr. Ellis said about $185,440 was spent to calculate the mass flux using this method. The Consortium has completed the data collection for their transect studies and has calculated mass flux. The results, Dr. Ellis said, will be presented at the spring 1999 Battelle conference and in hydrogeological journals after they receive peer review. An analysis of results indicate that the simple well data approach and the complicated transect study approach yielded similar mass flux estimates. Given the lower cost associated with the former, Dr. Ellis recommended using well data to calculate mass flux at sites that already have good well networks in place. In summary, Dr. Ellis said that about 160 to 170 pounds of chlorocarbons are being biodegraded per year at Dover AFB.

Future Natural Attenuation Projects

Dr. Ellis said the Consortium is embarking on Phase II of the natural attenuation program. During Phase II, the Consortium plans to make efforts to:

• Understand biodegradation of high concentration chlorinated solvents. Dr. Ellis said many people have already been convinced that natural attenuation is a reasonable approach for plumes with low or modest contaminant concentrations. The Consortium is interested in determining how biodegradation processes operate at higher contaminant concentrations..
• Examine how DNAPL is biodegraded at source areas. Dr. Ellis stressed that several NAPL source areas support bacterial growth. In the past, he noted, scientists believed that TCE proved toxic to bacteria. In recent years, however, that belief has been changing. Dr. Ellis said that some evidence suggests that biological reactions play a major role in constituent destruction at source areas. In fact, he continued, investigators believe about 50% of all chlorinated solvent destruction at Dover AFB took place within the source zone. To determine whether source zones foster biodegradative activities, Dr. Ellis noted, investigators should look for rapid accumulations of cis-DCE and vinyl chloride. If these contaminant concentrations are rising rapidly, it is a strong indication that reductive dehalogenation is taking place in the source zone. Some source zones, he continued, contain sufficient electron donors to facilitate the reduction reaction.
• Add biological activities to source paradigms. Dr. Ellis stressed that conceptual models of source areas are currently incomplete because investigators have not accounted for the biological processes ongoing at source zones.
• Track water packages

Dr. Ellis said that the Consortium will choose two Phase II demonstration sites. One site, Kelly AFB, has already been chosen and Work Plan development has been initiated.

Interactions Between Surfactant Flushing and Natural Attenuation

Dr. Ellis said some scientists have estimated that natural attenuation, as a stand-alone treatment, could only remediate about 20% of NAPL sites. Dr. Ellis said the real question is whether natural attenuation can serve as a useful component of a treatment train. He predicted that 60% to 70% of sites would benefit from natural attenuation if it was employed as part of a treatment train. Dr. Ellis said that DuPont worked on one site, in Texas, where the combination of surfactant flooding and natural attenuation was highly successful. Dr. Ellis said, however, that there are several points that must be considered if investigators are thinking of using natural attenuation as a follow-up to surfactant flushing.

Dr. Ellis noted that surfactants can benefit bacterial organisms in the following ways:

• Bioavailability might be increased.
• Bacterial growth might be increased because surfactants serve as good substrates and contain bacterial food sources (i.e., carbon, phosphorus, and nitrogen).

Conversely, Dr. Ellis noted that surfactants can also exert negative effects on bacterial populations by:

• Mobilizing bacteria. Dr. Ellis noted that bacteria, like other charged particles, can be suspended and removed by surfactants.
• Disrupting bacterial colonies. Dr. Ellis noted that many types of bacteria live in layered colonies known as biofilms. Organisms living in different layers have different characteristics and functions. Dr. Ellis said some bacterial species cannot survive if their layered colonies are not intact. He also noted that EPA has shown that biofilm colonies take a long time to reestablish after a disturbance. The introduction of surfactants, Dr. Ellis noted, could cause such a disturbance.
• Exposing methanogens to oxygen. Dr. Ellis cautioned investigators against changing the redox state of the subsurface. He said that bioactive source areas are often very reduced environments. He said a significant quantity of oxygen could be introduced to the subsurface if surfactants are extracted, treated with an air stripper, and reinjected back into the ground. Dr. Ellis stressed that many methanogens cannot withstand exposures to oxygen.
• Selectively removing benzene, toluene, ethylbenzene, and xylene (BTEX). Dr. Ellis noted that NAPL sources are rarely composed solely of chlorinated solvents. In many cases, other compounds in the waste mixture facilitate reductive dehalogenation processes by serving as a food source or electron donor. BTEX is thought to facilitate bacterial processes. Dr. Ellis expressed concern that surfactants would selectively remove BTEX from waste mixtures. Such an occurrence, he stressed, would have a deleterious effect on bacteria. Dr. Pope responded to Dr. Ellis' statement by noting that it is well documented in the literature that surfactant floods do not selectively remove BTEX compounds.

Dr. Ellis also noted that bacterial populations can prove deleterious to surfactants by degrading them. He warned investigators that laboratory tests indicating relationships between surfactants and bacteria do not always mimic the interactions in the field. He said that quick reproductive rates yield many bacterial mutants. It is more likely, he continued, that a surfactant-eating mutant will develop in the field than the laboratory.

Dr. Ellis also noted that several bacterial species produce their own surfactants. They do this, he noted, to increase their ability to ingest dissolved compounds through their cell walls. Dr. Ellis said he first became aware of bacterial surfactants while working on gas station remedial projects. At these sites, he noted, foam (bacterial surfactant) started emerging from the subsurface after 3 months of extraction. He said a large slug of free product, which was mobilized by the bacterial surfactant, would accompany the foam.

Dr. Ellis reminded the meeting participants that surfactants are not the only materials that can be injected into the ground. In fact, he said, renewed interest has been generated in the area of bioaugmentation, a process where bacteria are introduced into the subsurface. At Dover AFB, Dr. Ellis said, some researchers are experimenting with bioaugmentation and receiving very encouraging results.

Dr. Ellis said inadequate information is presently available to predict how surfactants and bacterial organisms will react to each other at a given site. He warned participants that killing bacteria at a natural attenuation site can have serious ramifications on plume size. Even if a surfactant flush could remove 90% of NAPL, he continued, the remaining 10% could still cause a large problem if all of the microbes in the area are destroyed or removed. Dr. Ellis said that no one can predict how long it takes bacterial populations to recover after being killed or removed from the subsurface. With no contaminant-destroying microbes available, Dr. Ellis stressed, the plume could increase in size even without 90% of its original mass.

In closing, Dr. Ellis asked meeting participants to understand the biology at their sites before proceeding with their activities. Also, he stressed the importance of adding biological activities to source paradigms.

Dr. Ellis fielded comments from the audience after completing his talk.. Dr. Annable noted that cosolvent flushing and natural attenuation technologies will be combined at the Sage Dry Cleaning site. He said that the cosolvent flush has been completed at this site and that the microbial population does not appear to be adversely impacted. Dr. Harwell said that some investigators have been talking about revisiting flushed sites to determine how the flushes impacted subsurface site biology. Dr. Pope agreed that such efforts would be very beneficial, but cautioned that obtaining funding could be a challenge because of (1) artificial barriers that separate biological and chemical studies, and (2) the difficulty that arises when trying to establish interdisciplinary teams. Ms. Yeh said that field acti vities are scheduled to begin at Camp Lejeune, a site contaminated with Varsol and PCE, in January 1999. Dr. Ellis said he would speak to the Consortium about collecting 2 or 3 samples before and after the Camp Lejeune flush to determine the impact on subsurface biology. Ms. Yeh and Dr. Ellis agreed to contact each other after the meeting.

REPORT FROM THE ITRC WORKING GROUP
Ms. Nancy Worst, WGA

Ms. Nancy Worst provided a brief description of the ITRC's history and activities. Ms. Worst noted that state agencies have been known to impose barriers to the development of innovative technology. Ms. Worst said the ITRC was established three years ago to remove these state barriers. The ITRC's mission is to create tools and strategies to reduce interstate barriers to the development of new and useful environmental technologies.

The ITRC has representatives from 27 states across the nation. Although it is state led, Ms. Worst continued, many other entities act as participants or sponsors, including the WGA, Southern States Energy Board, DOE, the Department of Defense, EPA, industrial representatives, and other stakeholders. Starting in January, Ms. Worst noted, the ITRC will be moved to Washington, D.C., under the sponsorship of the Environmental Council of States. Ms. Worst said affiliation with this new sponsor will give the ITRC national breadth and will likely attract more states to participate.

Since its inception, the ITRC has focused its efforts in seven technological areas:

• Accelerated site characterization. Ms. Worst said ITRC's involvement in this area was primarily with the Navy's pulsing laser sensor, a tool that provides immediate information during site investigations.
• In situ bioremediation. Ms. Worst said the ITRC developed project guidelines to help project managers understand the process of in situ bioremediation. In addition, she noted, the ITRC and RTDF Bioremediation Consortium worked together to create a training course that targets state regulators, consultants, and problem-holders. Ms. Worst said the course has been presented in a number of regions throughout the country and has been well attended.
• Metals in soil. Ms. Worst said the ITRC did an overview of available technologies.
• Permeable barrier walls
• Policy regulation issues. Ms. Worst said the ITRC has been involved with reinjection issues pertaining to biotreatment projects.
• Plasma technologies
• Thermal desorption

Ms. Worst said the ITRC helps to maximize limited state resources. She stressed that single states cannot be expected to eliminate barriers. By banding together and working in conjunction, however, states can make much more progress. Ms. Worst noted that the ITRC generates three types of products: (1) technical guidelines, (2) training courses, and (3) networks that connect state project managers with technical experts. Ms. Worst said the ITRC's products help state program managers in many ways. First, they lessen uncertainties about how to review and whether to approve an innovative technology. Second, they provide advance knowledge of the technology so that learning curves can be shortened. Also, she said, the products provide a consistent and predictable process for reviewing innovative technologies. These advantages have led to:

• A shortening in the length of time it takes for a technology to receive regulatory approval. Ms. Worst said that ITRC products are credited as shortening (1) review times by 20% in New Jersey, and (2) the permitting process by 2 to 3 months in Massachusetts.
• Increased confidence to approve innovative technologies.. In Colorado, Ms. Worst noted, the ITRC helped establish permeable barrier walls as a standard remedial technology. Likewise, in New York, the ITRC helped establish a routine permitting system for thermal desorption technologies.
• New state policies. Ms. Worst said the ITRC's technical guidelines are being incorporated into state policies. In New York, she noted, ITRC guidance was pulled directly into state guidance. Additionally, she continued, two states have used the In Situ Bioremediation training document as a guide to develop natural attenuation policy.

Ms. Worst said that additional information about ITRC can be obtained through the Internet (www.westgov.org/itrc) or by contacting the ITRC co-chairs (James Allen and Brian Sogorka). Ms. Worst invited participants to talk about ways the RTDF In Situ Flushing Action Team and the ITRC could collaborate. Dr. Wood said he would be interested in having the ITRC work with the RTDF team to reduce the amount of time required to get a permit. Ms. Yeh and Dr. Harwell said they would like the ITRC to research reinjection policies across different states. In North Carolina, Ms. Yeh said, regulators have agreed to allow surfactant reinjection if at least 95% of DNAPL is removed before reinjection. Ms. Yeh said she would like to know whether other states would adopt the 95% rule. Mr. Shoemaker said he would be interested in having the RTDF and ITRC collaborate to put out a regulatory guidance document. After getting feedback from the group, Mr. Shoemaker said the RTDF team would likely be ready to embark on a joint partnership during fiscal year 1999.

Ms. Worst agreed that there are many areas in which the ITRC could be of service to the RTDF team. She advised the team to identify a contact person who could act as the interface between the two groups. She also advised having a representative attend the November 1998 ITRC meeting. At these meetings, she explained, the ITRC gathers information about technologies they are considering.

FIELD DEMONSTRATION REPORTS AND UPDATES

In Situ Field Scale Evaluation of Surfactant Enhanced DNAPL Recovery Using Single-Well
Push-Pull Tests
Dr. Jennifer Field, Oregon State University

Dr. Jennifer Field opened her discussion by noting that surfactant phase behavior and solubilization potential are affected by the way that surfactants move through the subsurface. She said that any losses or changes in the composition can affect a surfactant's ability to solubilize or mobilize DNAPL. For this reason, she said, investigators need a simple pilot-scale tool to help predict how surfactants will be altered in the subsurface. Dr. Field said her team is trying to develop such a tool. Toward this end, her team is experimenting with the push-pull test, a test originally developed to evaluate in situ biological reactions. Dr. Field's team has three objectives:

• To develop a modified push-pull test for use in identifying and quantifying the effects of sorption, precipitation, and biodegradation on the fate and transport of injected surfactants.
• To use the developed test method to quantify the effects of these processes on the ability of injected surfactants to solubilize and mobilize residual TCE.
• To demonstrate the utility of the developed test method at a test site.

Dr. Field explained that the push-pull test involves a single well and consists of an injection phase, a resting phase, and an extraction phase. During the injection phase, a prepared solution of surfactant and/or tracer is introduced into the well over a time interval of the investigator's choosing. The investigator chooses how much of the aquifer to interrogate by choosing the amount of solution to add. During the extraction phase, the flow is reversed and water flows back along the same pathway. Water is sampled at timed intervals when it reaches the surface, resulting in a series of breakthrough curves. Dr. Field noted that the data provided from the push-pull well test can be presented in a number of ways.

Dr. Field said there are several advantages associated with push-pull tests, including:

• At the pilot scale, where regulatory concern is often expressed, investigators can define the volume of the aquifer that they interrogate.
• The test is inexpensive because an existing monitoring well can be used and other required equipment consists of plastic carboys, braided hoses, and an on-off switch for adding solution. The injection phase, Dr. Field noted, simply requires a gravity feed or pump; the extraction phase can be performed using pumps or bailers.
• Multiple tests can be performed in a single day.
• The test allows for large sample volumes. Dr. Field said the push-pull test allows for a much larger sampling volume than small soil core tests. As a result, the push-pull test can either be used as a substitute or compliment to soil core testing.

Dr. Field said that the push-pull test can be modeled in the laboratory using 1 meter long, wedge-shaped polypropylene models. She said that investigators can use the models to get an idea of how surfactants flow through the subsurface and to better understand breakthrough curves. Dr. Field's team has used laboratory models and field tests to evaluate the sorption properties of three surfactants:

• Alkylbenzylsulfonate. Dr. Field's team used a laboratory model, filled with uncontaminated sediments from Lawrence Livermore site #300, to evaluate the properties of alkylbenzyl-sulfonate. Dr. Field said that breakthrough curves indicated that various components of the test solution had different separation histories. Likewise, mass recovery curves indicated that different components of the surfactant were recovered at different rates. From these curves, Dr. Field's team concluded that this surfactant separates during transport. This conclusion was confirmed when the surfactant was tested in the field at an Oregon State University site. Such confirmation suggests that findings in the laboratory can help predict activities in the field.
• Dowfax. Dr. Field said that Dowfax was also initially tested in the laboratory using the Lawrence Livermore site #300 model described above. Unlike alkylbenzylsulfonate, Dowfax's breakthrough curve indicated very conservative behavior. That is, its curve was very similar to bromide's curve. Based on this finding, Dr. Field's team concluded that Dowfax has very favorable transport properties. As a follow-up experiment, the team performed a number of sequential push-pull tests within a physical aquifer model that contained about 5% residual TCE. Dr. Field said that the Dowfax retained its conservative behavior in the presence of TCE. TCE recovery rates, however, declined with each additional push-pull test. Dr.. Field said the team cannot explain this finding and would appreciate input on this matter.
• Aerosol MA 80-I. Dr. Field said that her team recently started evaluating Aerosol MA 80-I. In her first laboratory experiment, which was performed in the absence of TCE, Dr. Field found that breakthrough curves indicated that the surfactant had conservative behavior. After getting these results, Dr. Field said that she repeated the experiment in the presence of TCE. She said that a conservative breakthrough curve was recorded at the first port, but no breakthrough curves were apparent at ports 2 or 3, the locations where surfactant encountered TCE. Further investigation revealed that the surfactant being extracted was not the same as the species injected. To fix the problem, Dr. Field said, her team reflushed the system with 10 pore volumes of sodium chloride in an attempt to exchange out some of the calcium in the system. By doing so, the team successfully restored the surfactant's conservative behavior at some of the ports.

Dr. Field concluded her talk by asking participants to contact her if they know of a site that her team can use for demonstrations.

The Bachman Road Site
Dr. Kurt Pennell, Georgia Institute of Technology

Dr. Kurt Pennell said that two innovative technologies--Surfactant Enhanced Aquifer Remediation (SEAR) and halorespiration--are scheduled to be tested at the Bachman Road site. Dr. Pennell opened his discussion with a brief site description. Dr. Pennell said that the Bachman Road site is a commercial area. In the past, it housed a dry cleaner, but it is now occupied by a jewelry store and copy center. Dr. Pennell said that the site is contaminated with PCE and that a number of contaminated ground-water plumes underlie the site and discharge to Lake Huron (located 800 feet away). He said the conditions at the site are ideal for a SEAR test (i.e., the water table sits about 8 to 10 feet below the ground and a clay layer is present about 25 feet below the ground).

Dr. Pennell said that Brown and Root Environmental conducted the initial site characterization at the Bachman Road site. Unfortunately, their characterization failed to adequately delineate a source zone or define the extent of the problem. Based on their site characterization results, Dr. Pennell continued, Brown and Root Environmental drafted a pump and treat remedial design system. Dr. Pennell stressed that the costs cited for this treatment system (about $2 million) are misleadingly low because the design does not account for remediation of the source zone.

Dr. Pennell said that additional site characterization was performed under the SEAR program. The SEAR team collected additional information from existing monitoring wells and collected a number of soil samples and soil cores. Dr. Pennell noted that an angle drill core was used to collect samples under the former dry cleaners' foundation. Collection of these samples was motivated by the fact that PCE spill stains were found in the dry cleaners' basement. Dr. Pennell said the SEAR's team site characterization indicated that (1) the source of the PCE spill is under the former dry cleaners' foundation and (2) two zones of contamination are present.

Dr. Pennell said that several practical considerations are being addressed to select the most appropriate surfactant, including:

• Compatibility. Dr. Pennell said the team is evaluating whether the surfactant could prove toxic and whether it will biodegrade.
• Surfactant losses. Dr. Pennell noted that the team is trying to estimate how much of the surfactant will be lost through sorption, precipitation, and biodegradation.
• Recovery process. Dr. Pennell said the team is trying to determine whether solubilization or mobilization is preferable at this site.
• Delivery issues. Dr. Pennell said the team is evaluating permeability, viscosity, and density issues.
• Economic considerations. Dr. Pennell stressed that economic concerns may be difficult to hurdle at this site. Because Brown and Root Environmental indicated that pump and treat costs would be low, the Department of Environmental Quality might be reluctant to invest in other technologies. Dr. Pennell said the SEAR team will have to convince the regulators that the problem at the site is much worse than originally thought and that Brown and Root Environmental's cost estimate is too low.

Dr. Pennell encouraged participants to review the 2-D box studies that the SEAR team conducted at this site. He said results will be presented at a Monterey conference and published soon.

Dr. Pennell closed his discussion with a brief description of the halorespiration project that is being conducted at this site. He stressed that he is not involved with the project and advised participants to contact the University of Michigan's Jim Tiedje for additional information. Dr. Pennell said that a portion of the Bachman Road site has already been remediated via reductive dehalogenation. In many cases, Dr. Pennell continued, the rate at which reactions occur is limited by the number of free electrons in a system. Halorespiration, Dr. Pennell stressed, increases the number of available free electrons by adding electron donor material (i.e., substrate). By doing so, halorespiration enhances biodegradation reactions and increases the likelihood that PCE will degrade all the way to ethene (a safe constituent) rather than stopping at vinyl chloride (a toxic constituent). Dr. Pennell said that the University of Michigan research team is considering implementing the halorespiration technology via bioaugmentation or biostimulation. He said the team plans to install a magnesium peroxide wall near Lake Huron to ensure that no additional contaminants are introduced.

Millican Field
Mr. Fred Holzmer, Duke Engineering & Services, Inc.

Mr. Fred Holzmer noted that the Navy Facilities Engineering Command (NAVFAC) has agreed to fund four side-by-side test demonstration projects at Millican Field in Pearl Harbor, Hawaii. Mr. Holzmer said that SEAR has been chosen as one of the technologies. He noted that the SEAR team has encountered numerous challenges since embarking on this project because:

• The LNAPL at Millican Field has a very high viscosity. Mr. Holzmer said the LNAPL at the Pearl Harbor site is called Navy Special Fuel Oil (NSFO) and has a viscosity of about 1,000 to 3,000 centipoise.
• No commercially available surfactants are capable of solubilizing NFSO.
• No previous work had ever been performed on such a highly viscous NAPL.
• The hydrogeology at the site is very complex. Mr. Holzmer said that the subsurface is highly fractured. In addition, the LNAPL is located below a layer of relatively low permeability.

Mr. Holzmer said that the expertise of multiple scientists was called upon to identify a surfactant that would solubilize NFSO. After much experimentation, a custom-designed surfactant was generated. The surfactant has been named IsalChem 145(PO)_3,9 Sodium Ether. It is a C₁₃ alcohol that is perpoxylated with a sodium sulfate at one end. The feature that really sets this surfactant apart, Mr. Holzmer emphasized, is the fact that the surfactant has a highly branched R group, no ethylene oxide groups, and many propylene side groups. Mr. Holzmer said that the surfactant must be heated in order for it to solubilize NSFO. (At 60 degrees Celsius, the surfactant has a viscosity of 200 centipoise.) Although NFSO solubilizes into the surfactant more readily at 70 degrees Celsius , the surfactant will only be heated to 50 degrees Celsius at Millican Field because the plastic in onsite injection and recovery wells cannot withstand higher temperatures. Mr. Holzmer said this limitation does not pose a large hardship because solubility difference between 50 and 70 degrees Celsius is not too large. Mr. Holzmer said the treatment zone will be preheated before surfactants are injected.

Mr. Holzmer noted that the SEAR team has tested the interaction between NFSO and the custom-made surfactant extensively in the laboratory. In laboratory column tests, Mr. Holzmer reported, the vast majority of NFSO is removed by the surfactant, but a thin coating of asphalt-type consistency remains in the cell. Fortunately, Mr. Holzmer said, this coating appears to be immobile.

Mr. Holzmer said that the SEAR team plans to conduct pre-and post-partitioning interwell tracer tests to evaluate the efficacy of the in situ flushing demonstration. Mr. Holzmer said tests were performed to ensure that the tracers would work properly in the presence of the custom-made surfactant. The result indicated that they do, although the tracers must also be heated. Tests conducted to date, Mr. Holzmer noted, indicate that the partitioning coefficient for NSFO and its residual asphalt-like coating are different.

Mr. Holzmer provided a schedule for the four demonstration projects that are scheduled to take place at Millican Field:

• Belt skimming: scheduled for initiation in mid-September 1998
• Vacuum enhanced belt skimming: scheduled for initiation in early October 1998
• Electroheat and pumping: scheduled for initiation by mid-October 1998
• Thermally enhanced SEAR: scheduled for initiation in early December 1998

Mr. Holzmer noted that SEAR is the only one of the above-listed technologies that addresses the removal of residual NAPL. Mr. Holzmer closed his discussion by noting that the custom-made surfactant could prove helpful on other highly viscous materials (e.g., coal tars) as well as chlorinated solvents (e.g., PCE). He said that this surfactant is being considered for use at Camp Lejeune.

Interagency DNAPL Consortium
Dr. Thomas Early, Oak Ridge National Laboratory

Dr. Thomas Early provided an update on the Interagency DNAPL Consortium's activities. Two years ago, Dr. Early noted, several federal agencies decided to band together to address common DNAPL problems. These agencies agreed to select relatively mature DNAPL-remediation innovative technologies and to test them in side-by-side demonstrations. Such an approach, Dr. Early noted, would allow for direct comparisons of different technologies' cost and efficacy.. The agencies also agreed, Dr. Early continued, to coordinate their activities with regulators to gain regulatory acceptance of the innovative technologies.

Dr. Early said the Consortium has selected Cape Canaveral's Launch Complex 34 as the site for their demonstration project. This site was chosen because it has simple hydrogeology, relatively shallow ground water, DNAPL, and numerous TCE hot spots. Dr. Early said the Consortium completed preliminary site characterization at the Launch 34 complex in June 1998. The results indicated that the highest TCE concentrations are located in two zones (a clay zone and a finer grain zone) and that a large quantity of DNAPL is located under a building.

Dr. Early said that the Technical Advisory Group met in April 1998 and decided that the following innovative technologies will be tested:

• Thermal technologies. Dr. Early said the Consortium has not decided whether they will use a steam or an electrical resistance technology.
• In situ chemical oxidation. Dr. Early said that the Consortium is leaning toward using permanganate, but is also conducting a Feasibility Study to evaluate using Fenton's reaction.
• Surfactant flushing

Although the Consortium originally planned to perform side-by-side demonstrations, Dr. Early said some consideration is being given to installing the thermal technology demonstration at another location at Cape Canaveral. Dr. Early said this suggestion has been put forth because some people fear placing three projects in the same area will compromise hydraulic control.

Dr. Early summarized the time frame of future activities as follows:

• Complete design review and vendor selection: October 1998
• Conduct predemonstration site characterization: Fall 1998
• Conduct predemonstration performance assessment: Fall/Winter 1998/1999
• Conduct demonstration construction and operation: Spring 1999 through Winter 2000
• Conduct demonstration performance assessment: Summer 1999 through Summer 2000

Sage's Dry Cleaners, Florida
Mr. Kevin Warner, Levine*Fricke*Recon

Mr. Kevin Warner described a cosolvent pilot-scale flushing demonstration that was conducted at Sage's Dry Cleaners in Jacksonville, Florida. Mr. Warner noted that four objectives had been cited before the project was initiated:

• Achieve enhanced mass recovery of PCE.
• Obtain design parameters for the full-scale design of a flushing remediation system.
• Test the AKZO macroporous polymer (MPP) system to determine how effectively it treats extracted wastes.
• Convince regulators to allow flushing technology at this site.

Mr. Warner provided a brief description of the site. He said that DNAPL distribution had been delineated using soil borings, electrical resistivity, and ultraviolet- and infrared-laser induced fluorescence. Mr. Warner briefly described the well configuration that was used during the flushing demonstration and noted that the team was able to achieve hydraulic control.

During the cosolvent flush, Mr. Warner reported, his team injected water and alcohol into two different zones. Mr. Warner said the injection flushed the test cell and created an alcohol blanket underneath the test zone that served to solubilize any downward-mobilizing PCE. Mr. Warner said that the flush was designed to sweep the NAPL zone rather than the entire swept zones. He said that his team underestimated the amount of alcohol that was needed for this project. Mr.. Warner said that significant quantities of PCE were withdrawn from recovery wells #3, #6, and #7. Preliminary estimates indicate that the flushing test extracted 41 liters of PCE from the subsurface.

Mr. Warner said that the wastestream from the recovery wells was treated with the AKZO MMP system. He said the system was so effective that he would have felt confident reinjecting the alcohol into the ground if this had been a full-scale project. Mr. Warner stressed that alcohols can be treated and reused. He said that the team leased the AKZO MPP system for about $4,000 a week. He noted that the team had also procured an air stripper tower to "polish" the effluent coming out of the AKZO MPP system. After a couple of days, however, the team decided that this step was not necessary. Mr. Warner said that the team spent $40,000 to $60,000 for offsite disposal of their treated fluids (ethanol and water).

Mr. Warner noted that EPA and the University of Florida are collecting some samples at the site to determine whether bioremediation is ongoing. He said some consideration is being given to cometabolic technologies.

In closing, Mr. Warner noted that the pilot test cost $400,000. He said this price was reasonable considering that a pump and treat system would have to be operated for 10 years to extract an equivalent volume of PCE.

Activities Conducted by Surbec Environmental
Mr. Mark Hasegawa, Surbec Environmental

Mr. Hasegawa opened his talk with an overview of Surbec Environmental's approach to in situ flushing technology demonstrations. He noted that Surbec Environmental draws on the expertise of an interdisciplinary team, so that they can take a more holistic approach when implementing demonstration projects. Mr. Hasegawa said that Surbec Environmental uses an integrative approach and regards treatment of effluent as a high priority. Mr. Hasegawa stressed that treating the effluent is important so that (1) surfactants can be recovered and reused and (2) costly offsite waste disposal can be avoided. He said that Surbec Environmental often uses treatment systems (e.g., packed tower air strippers and hollow fiber membrane strippers) and ultrafiltration systems (e.g., tray strippers).

Mr. Hasegawa provided brief descriptions of several projects that Surbec Environmental has been involved with:

• Tinker AFB. Mr. Hasegawa said his team conducted a flushing project at the Southwestern Tank area at Tinker AFB. He said "bioslurping" had been conducted at the site for years and site representatives were confident that no free-phase product remained under the site. They had based their conclusion, Mr. Hasegawa noted, on the fact that no free product had been observed in base recovery wells. Mr. Hasegawa said that Surbec Environmental drilled some additional wells and found 2 to 3 feet of free product under the site.

Mr. Hasegawa said that Dowfax was used to remove LNAPL at Tinker AFB. During this demonstration, several effluent treatment systems were evaluated including (1) a packed tower air stripper, (2) a hollow fiber membrane stripper unit, and (3) a MEUF tray stripper. Mr. Hasegawa said that the packed tower air stripper and hollow fiber membrane stripper unit performed with similar efficacy. The latter, however, had the advantage of not producing foam. Using the treatment systems, about 85% of the injected surfactant was recovered.

Mr. Hasegawa noted that free product migrated to the base recovery wells three weeks after the flush was performed. Mr. Hasegawa said he thinks the product moved to the well because the surfactant affected the multiphase flow characteristics of the NAPL.

• Underground Storage Tank (UST) site in Shawnee, Oklahoma. Mr. Hasegawa said his team used a tray stripper to treat recovered effluent at a UST site in Shawnee, Oklahoma. After treatment was completed, he said, a few hundred gallons of surfactant were reinjected into the subsurface.
• McClellan AFB. Mr. Hasegawa said his team is currently assisting with a field demonstration project involving TCE removal at McClellan AFB near Sacramento, California. Mr. Hasegawa said the water table at this site is 110 to 120 feet deep and that it is questionable whether there is a contiguous confining layer underneath. The Work Implementation Plan has been completed and field investigation activities have been initiated. Mr. Hasegawa said his team plans to search for NAPL at this site. Flushing activities are expected to start in March 1999, on a plot that is 20 feet by 30 feet.
• Paducah Gaseous Diffusion Plant. Mr. Hasegawa said his team is conducting a bench-scale treatability study at this site. Contaminants of concern include Technetium 99, a fission byproduct. Mr. Hasegawa said efforts are being made to evaluate the potential for contaminant solubilization, ultrasolubilization, and mobilization. As part of the bench-scale analysis, he noted, surfactant recovery and reuse is being considered and air stripping and ultrafiltration systems are being tested. Mr. Hasegawa said results are expected in December 1999.
• Cape Canaveral. Mr. Hasegawa said that Surbec Environmental will be assisting with some pre-design work at Cape Canaveral. Their goal will be to remediate a 50 foot by 50 foot TCE-contaminated plot.
• Spartan Chemical. Mr. Hasegawa said his team will be involved in a field demonstration at the Spartan Chemical site in Michigan. He said this site has DNAPL and LNAPL and a wide variety of contaminants, including TCE, BTEX, PCE, and methylene chloride. He said that part of the surfactant screening process at this site involves an analysis of the effects that surfactants and bacteria could have upon each other. Mr. Hasegawa said the project is scheduled to start in early 1999 and will likely involve a 20 foot by 30 foot demonstration plot.

CLOSING REMARKS
Dr. A. Lynn Wood, U.S. Environmental Protection Agency (EPA)
Mr. Stephen Shoemaker, E.I. DuPont DeNemours & Company, Inc.

Dr. Wood and Mr. Shoemaker thanked meeting participants for their enthusiasm. Dr. Wood said he would like to identify ways to facilitate communication between team members between meetings. He said he has talked to Carolyn Perroni (Environmental Management Services) about establishing a password-restricted Web site at which RTDF members can review unpublished draft data. In closing, Dr. Wood encouraged participants to provide feedback on the meeting format and agenda.

Attachment A
Final Attendee List

In Situ Flushing
Action Team Meeting

Sheraton Grand Hotel
Irving, TX
September 14-15, 1998

Final Attendee List

*Michael Annable Associate Professor Department of Environmental Engineering University of Florida 217 Black Hall Gainesville, FL 32611-2013 352-392-3294 Fax: 352-392-3076 E-mail: manna@eng.ufl.edu Stephen Byrne Regulatory Services Manager Environmental Services Department Cytec Industries, Inc. 1300 Mt. Kemble Avenue Morristown, NJ 07960 973-425-8406 Fax: 973-425-0185 E-mail: steve_byrne@gm.cytec.com Paul Devane Environmental Engineer Air Force Research Laboratory 139 Barnes Drive - Suite 2 Tyndall AFB, FL 32403-2323 850-283-6288 Fax: 850-283-6064 E-mail: paul_devane@ccmail.aleq.tyndall.af.mil *Thomas Early Senior Development Staff Oak Ridge National Laboratory Building 1509 - Bethel Valley Road P.O. Box 2008 (MS-6400) Oak Ridge, TN 37831-6409 423-576-2103 Fax: 423-574-7420 E-mail: eot@ornl.gov *David Ellis DuPont Specialty Chemicals Barley Mill Plaza - Building 27 P.O. Box 80027 - Routes 141 & 48 Wilmington, DE 19805 302-892-7445 Fax: 302-892-7641 E-mail: ellisde@csoc.dnet.dupont.com *Jennifer Field Associate Professor Department of Environmental and Molecular Toxicology Oregon State University Corvallis, OR 97331 541-737-2265 Fax: 541-737-0497 E-mail: jennifer.field@orst.edu Richard Goehlert Remedial Project Manager U.S. Environmental Protection Agency JFK Federal Building (HBO) Boston, MA 02203 617-573-5742 Fax: 617-473-9662 E-mail: goehlert.dick@epamail.epa.gov Neeraj Gupta Principal Research Scientist Environmental Restoration Department Battelle Memorial Institute 505 King Avenue Columbus, OH 43201 614-424-3820 Fax: 614-424-3667 E-mail: gupta@battelle.org *Jeff Harwell Professor University of Oklahoma 100 East Boyd - SEC, T335 Norman, OK 73019-0628 405-325-5814 Fax: 405-325-5813 E-mail: jharwell@ou.edu *Mark Hasegawa Operations Manager Surbec Environmental 3200 Marshall Avenue - Suite 200 Norman, OK 73072 405-364-9726 Fax: 405-366-1798 E-mail: markhase@aol.com *Fred Holzmer Hydrogeologist Duke Engineering & Services, Inc. 9111 Research Boulevard Austin, TX 78758 C. Wayne Ives Hydrogeologist Waste Management Division New Hampshire Department of Environmental Services 6 Hazen Drive P.O. Box 95 Concord, NH 03302-0095 603-271-2890 Fax: 603-271-2456 E-mail: w_ives@des.state.nh.us Richard Jahnke Technology Manager, Commercial Development The Lubrizol Corporation 29400 Lakeland Boulevard Wickliffe, OH 44092-2298 440-943-1200 Fax: 440-944-6847 E-mail: rwj@lubrizol.com Minquan Jin Engineer Duke Engineering & Services, Inc. 9111 Research Boulevard Austin, TX 78758 512-425-2016 Fax: 512-425-9000 E-mail: mjin@duke-energy.com Robert Jones Research Scientist The Lubrizol Corporation 29400 Lakeland Boulevard (402L) Wickliffe, OH 44092 440-943-4200 Fax: 440-943-9094 E-mail: rnj@lubrizol.com Bill Kosco Environmental Engineer Tetra Tech EM, Inc. 625 Eden Park Drive - Suite 100 Cincinnati, OH 45202 513-564-8346 Fax: 513-241-0354 E-mail: koscow@ttemi.com Robert Legrand Senior Engineer Radian International P.O. Box 201088 Austin, TX 78720-1088 512-419-6147 Fax: 512-454-8807 E-mail: robert_legrand@radian.com John Londergan Senior Hydrogeologist Duke Engineering & Services, Inc. 9111 Research Boulevard Austin, TX 78758 512-425-2028 Fax: 512-425-2099 E-mail: jtlonder@duke-energy.com *George Losonsky Regional Manager IT/OHM Corporation 13400 Mohawk Road Clermont, FL 34711 352-394-8601 Fax: 352-394-7722 E-mail: glosonsk@ohm.com Wayne Lundberg Physical Scientist Aquisition Environmental Management Restoration Division U.S. Air Force 1801 Tenth Street - Suite 2 (ASC/EMR) Wright Patterson AFB, OH 45433-7626 937-255-7716 Fax: 937-255-4155 E-mail: wayne.lundberg@wpafb.af.mil Clarence Miller Professor Department of Chemical Engineering Rice University 6100 Main Street (MS 362) P.O. Box 1892 Houston, TX 77251-1892 713-527-4904 Fax: 713-285-5478 E-mail: camill@rice.edu Ken Moor Advisory Scientist Environmental Assessment Technology Environmental and Risk Assessment Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83401 208-526-8810 Fax: 208-526-0603 E-mail: ksm@intel.gov

Randy Parker Environmental Engineer U.S. Environmental Protection Agency 26 West Martin Luther King Drive (MS-481) Cincinnati, OH 45268 513-569-7271 Fax: 513-569-7143 E-mail: parker.randy@epamail.epa.gov *Kurt Pennell Assistant Professor Department of Civil & Environmental Engineering Georgia Institute of Technology 200 Bobby Dodd Way Daniel Laboratory (0512) Atlanta, GA 30332-0512 404-894-9365 Fax: 404-894-8266 E-mail: kpennell@ce.gatech.edu *Gary Pope Director Center for Petroleum and Geosystems Engineering The University of Texas at Austin CPE 2.502 (MC-C0300) 26th Street & Speedway Boulevard Austin, TX 78712 512-471-3235 Fax: 512-471-9678 E-mail: gary_pope@pe.utexas.edu Steve Rosansky Environmental Engineer Environmental Restoration Department Battelle 505 King Avenue Columbus, OH 43201-2693 614-424-7289 Fax: 614-424-3667 E-mail: rosansky@battelle.org Jeffrey Sacre Senior Environmental Engineer Ground Water Remediation Technologies Analysis Center (CTC) 2626 North Mesa Street - Suite 414 El Paso, TX 79902 915-845-3195 Fax: 915-845-3195 E-mail: sacrej@ctc.com Thomas Sawyer Department of Environmental and Molecular Toxicology Oregon State University Corvallis, OR 97331 541-737-2267 Fax: 541-737-0497 E-mail: sawyert@ucs.orst.edu Stephen Schmelling Director of Research National Risk Management Research Laboratory Subsurface Protection and Remediation Division U.S. Environmental Protection Agency 919 Kerr Research Drive P.O. Box 1198 Ada, OK 74821-1198 580-436-8540 Fax: 580-436-8582 E-mail: schmelling.steve@epamail.epa.gov *Stephen Shoemaker Consulting Associate DuPont Company 140 Cypress Station Drive - Suite 140 Houston, TX 77090 281-586-2513 Fax: 281-586-5650 E-mail: stephen.h.shoemaker@usa.dupont.com Mike Shook Advisory Scientist Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83415-2107 208-526-6945 Fax: 208-526-0875 E-mail: ook@inel.gov Henry Stopplecamp Assistant Manager Environmental Remediation Burlington Northern Santa Fe 4200 Deen Road Fort Worth, TX 76106 817-740-7357 Fax: 817-740-7250 E-mail: henry.stopplecamp@bnsf.com Leland Vane Chemical Engineer National Risk Management Research Laboratory U.S. Environmental Protection Agency 26 West Martin Luther King Drive (MS-443) Cincinnati, OH 45268 513-569-7799 Fax: 513-569-7677 E-mail: vane.leland@epamail.epa.gov *Kevin Warner Senior Associate Engineer Southeast Region Levin*Fricke*Recon 3382 Capital Circle, NE Tallahassee, FL 32308 850-422-2555 Fax: 850-422-2624 E-mail: kevin.warner@lfr.com Richard Willey Hydrologist U.S. Environmental Protection Agency JFK Federal Building (HBS) Boston, MA 02203 617-573-9639 Fax: 617-573-9662 E-mail: willey.dick@epamail.epa.gov *Lynn Wood Soil Scientist Abiotic Processes and Applications Subsurface Protection and Remediation Division U.S. Environmental Protection Agency Robert S. Kerr Environmental Research Center 919 Kerr Research Drive - P.O. Box 1198 Ada, OK 74820 580-436-8552 Fax: 580-436-8582 E-mail: wood.lynn@epamail.epa.gov *Nancy Worst ITRC Program Manager Western Governors Association 12517 Fallen Tower Austin, TX 78753 512-821-1942 Fax: 512-821-1968 E-mail: nworst@worldnet.att.net Kathleen Yager Environmental Engineer Technology Innovation Office U.S. Environmental Protection Agency 401 M Street, SW (5102G) Washington, DC 20460 703-603-1237 Fax: 703-603-9135 E-mail: yager.kathleen@epamail.epa.gov S. Laura Yeh Chemical Engineer Naval Facilities Engineering Service Center 1100 23rd Avenue (ESC 411) Port Hueneme, CA 93043-4370 805-982-1660 Fax: 805-982-4304 E-mail: yehsl@nfesc.navy.mil RTDF logistical and technical support provided by: Christine Hartnett Environmental Scientist Eastern Research Group, Inc. 8303 North MOPAC Expressway Building A - Suite 101 Austin, TX 78759 512-231-2260 Fax: 512-231-2261 E-mail: chartnett7@aol.com Susan Brager Murphy Conference Manager Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02421-3136 781-674-7347 Fax: 781-674-2906 E-mail: sbmurphy@erg.com Carolyn Perroni Senior Project Manager Environmental Management Support, Inc. 8601 Georgia Avenue - Suite 500 Silver Spring, MD 20910 301-589-5318 Fax: 301-589-8487 E-mail: cperroni@emsus.com Meg Vrablik Conference Coordinator Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02421-3136 781-674-7396 Fax: 781-674-2906 E-mail: mleitzel@erg.com

* Speaker

Attachment B
Revised Outline for Volume I

Topic	Assigned Team Members
1.1 Screening        1.1.1 Site Parameter                  NAPL (Yes/No)                  COC (Yes/No)                  Site hydrogeology                  Site information                      Site history                      Plume size                  Regulatory barriers
1.2 Conceptual Approach        Overview of the whole protocol
1.3 Site Characterization        Soil characterization (mineralogy, etc.)        NAPL characterization (density, viscosity)        Determining NAPL extent and distribution        Regulatory concerns to be addressed	Hasegawa, Ives, Field, Stopplecamp
1.4 General Evaluation Step        Is the site appropriate for flushing technology?
1.5 Design Process        1.5.1 Develop Design Criteria (for pilot-scale testing)        1.5.2 Laboratory Testing of Flushing Chemicals/Solution                  Initial selection criteria for surfactant/co-solvent (biodegradation/toxicity)                  Phase behavior (look at solubility and temperature effects)                  Viscosity                  IFT                  Batch                  Sorption                  Column Testing                  2-D test (unconfined)        1.5.3 Subsurface Modeling                  Hydrogeologic modeling (develop geosystems model)                  Flushing design (wellfield, hydraulic control, screens)                  Process design (amount of chemical, rates, etc.)                  Prediction of contaminant recovery, chemical recovery                  Model requirements and review, key features	Warner, Pope, Yeh, Pennell, Jahnke
1.5 (continued)        1.5.4 Treatment Engineering                  1.5.4..1 Effluent Stream Treatment                              Air-stripping + carbon (off-gas)                              Liquid/liquid absorption (PCE+ethanol+water)                              Membrane technologies                              Pervaporation                              Hollow fiber                              Rotating shear (VSEP)                              Steam stripping                              Liquid/liquid separation                              Extraction                              Precipitation                              Steam reforming (catalytic oxidation)                              UV oxidation                              Microbiological processes                  1.5.4.2 Remedial Agent Recovery/Reuse	Warner, Pope, Yeh, Pennell, Jahnke
1.6 Pilot-Scale Testing        Develop objectives        Regulatory issues        Process considerations (mobility control, etc.)        Wellfield installation        Facilities construction (tanks, etc.)
1.7 Performance Assessment
1.8 Scale up (Full-Scale Design)        Delineate the extent of the:                  NAPL zone                  Target flush zone                  Permeable zone        Is the pilot-scale data sufficient for full-scale design?                  Variability in media properties                  Variability in geochemical properties                  NAPL variability                  Existing well tests adequate        Additional data required to determine the well pattern                  New hydraulic well testing                  GPR                  Seismic                  CPT tests        Well pattern selection                  Well spacing                  Well screen interval                  System modeling                  Waste management and reuse	Annable, Shook, Wood, Sawyer Annable
1.8 Scale up (Full-Scale Design) (continued)        Well installation                  Soil core analysis                  Hydraulic well testing        Flood zone media characterization                  Heterogeneity                  Hydraulic containment                  Modeling        Flood zone NAPL characterization                  NAPL volume                  NAPL spatial distribution        Flood design                  Total throughput requirement to meet endpoints                  Effluent concentration and waste management                  Optimization of injection scheme                  Modeling        Effluent treatment                  Management of large scale floods                  Cost implications for agent selection        Performance assessment                  Effluent analysis                  PITT                  Core data                  Ground-water sampling	Annable Wood Wood Shook Shook