Sheraton Grand Hotel
Irving, Texas
January 7­8, 1998

WELCOME--TEAM UPDATE AND PROPOSED TEAM STRUCTURE
Dr. A. Lynn Wood, U.S. Environmental Protection Agency (EPA)
Mr. Stephen Shoemaker, E.I. DuPont DeNemours & Company, Inc.

Dr. Wood and Mr. 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 second official meeting. The co-chairs briefly summarized the proceedings of the first meeting, which was held in May 1997 at Hill Air Force Base (AFB). During the first meeting, the team:

• Learned about the current status of in situ flushing technologies. Several scientists presented data from demonstration projects that were conducted at Hill AFB.

• Talked about the major unmet developmental needs associated with the technology. The team identified technical and economic barriers that must be surpassed before in situ flushing technologies can be considered for widespread implementation.

• Generated a mission statement. The team agreed that the group's mission should be: to facilitate the development and implementation of in situ flushing technologies for site remediation.

• Identified action items and future activities that will help achieve the mission. The team generally agreed that there are five major action areas that need to be addressed together, as one project:

• Design a full-scale (i.e., commercial-size) demonstration.

• Develop a "best practices" handbook and a general protocol.

• Perform additional economic evaluations and compare the costs of in situ flushing technologies with other source remediation approaches.

• Develop systems that allow for remedial agent (e.g., surfactants or cosolvents) recovery and reuse.

• Analyze end-point issues and define success criteria by answering "How clean is clean?" (e.g., Can the technology be considered a success if it removes 98 to 99 percent of nonaqueous phase liquids [NAPL], or does 100 percent need to be removed?)

After recapping the proceedings of the first meeting, the co-chairs identified five goals for the second meeting:

• Regain the momentum and enthusiasm that was generated at the May 1997 meeting and continue formulating a "game plan" for the team. As noted by Dr. Wood, discussion is needed to further define the role of the team. While other RTDF teams are concentrating their efforts to sponsor field projects, this particular team has not expressed an interest to do so thus far. Based on feedback from others, Dr. Wood envisions this action team acting more as a "sounding board" and an "advisory board" for pilot projects.

• Organize into subgroups:

  • Economic Assessment and Remedial Agent Recovery/Reuse. This subgroup will address two of the five action areas that were identified at the May 1997 meeting. The co-chairs decided to combine these issues because they are so intimately connected.

  • Endpoint Assessment/Technical Performance Criteria

  • Technical Practices/Protocol

  • Full-Scale Design

  The co-chairs emphasized that participants are free to become involved in more than one subgroup or to switch subgroups at any time.

• Allow the subgroups to identify clear goals and strategies during breakout sessions.

• Provide an opportunity for subgroup leaders to summarize their goals and strategies and discuss the integration of these into the team mission.

• Learn about the latest developments in ongoing field demonstration projects.

SUBGROUP REPORTS

After the co-chairs welcomed the group and described the goals of the meeting, the participants separated into four subgroups and discussed goals and strategies for the remainder of the afternoon (January 7). The following morning (January 8), the entire team reconvened and subgroup leaders summarized the discussions from their breakout meetings.

Economic Assessment and Remedial Agent Recovery/Reuse
Subgroup Leader: Other Participants:	Jeff Harwell, University of Oklahoma Steve Byrne, Cytec Industries Jon Ginn, Hill AFB Richard Jackson, Duke Engineering & Services, Inc. Donald Lowe, Rice University Richard Schoenfeld, Lubrizol Corporation Leland Vane, EPA Kathleen Yager, EPA Technology Innovation Office (TIO)

Ways To Minimize Costs Associated With In Situ Flushing Technologies

Dr. Harwell offered some preliminary suggestions of ways to minimize costs associated with in situ flushing technologies. These include:

• Using hydraulic controls rather than sheet pilings to confine the treated area
• Choosing a low adsorbing surfactant that can be easily recovered
• Buying only enough surfactant-recovery equipment, and NAPL-disposal equipment to treat approximately 10 percent of a contaminated site, but putting in enough wells (the costs of wells is nearly negligible versus the overall cost of an in situ flush) to complete remediation within 5 years. Dr. Harwell recommends separating a contaminated site into ten segments and treating each segment one at a time, in a sequence beginning with the most upgradient area and ending with the most downgradient area. (After completing a flush in one segment, the surfactant should be recovered [for reinjection] and the recovery system and disposal equipment should be moved to the next segment.)
• Mobilizing pollutants rather than solubilizing them
• Not trying to clean the area to meet drinking water standards. Dr. Harwell emphasized that the goal of in situ flushing technologies should be to reach a point at which 1) plume migration can be stopped (flux from hot spot will be handled by biodegradation and adsorption) and 2) natural attenuation will be able to polish the treated zone.

Dr. Harwell estimated that adhering to the above-listed recommendations could reduce the cost associated with in situ flushing by 76 percent.

Future Subgroup Activities: Goals, Strategies, and Schedules

The subgroup identified four goals toward which they plan to work over the next year:

• Identify how to recover and reuse surfactants for different NAPLs (e.g., chlorohydrocarbons and nonvolatiles such as polychlorinated biphenyls or creosote) and summarize the technological status and cost of these methodologies. Leland Vane will head up this effort.
• Examine the pros and cons of using various "bottom-line" flushing cost measures and determine which measures are the most useful. Meeting participants are anxious for guidance in this area. As noted by several participants, some commonly used civil engineering measures, such as dollars per treated cubic yard ($/yd³) are not always very useful. Richard Jackson will head up this effort.
• Review and compare existing economic analyses, identify/analyze the assumptions used to generate the economic analyses, and present the results of the subgroup's findings in a "user- friendly" form. Steve Byrne, Jon Ginn, and Jeff Harwell will work together on this effort.
• Survey state regulators to find out what their attitude is towards surfactant injection and reinjection and use this information to produce "best-practice"guidelines. A few years ago, Richard Steimle headed up a similar effort and the information that he gathered was considered very useful. Given that regulators' attitudes towards injection/reinjection is rapidly changing, the subgroup believes that the survey should be updated. Kathleen Yager has been nominated to lead this effort. (Ms. Yager had not officially accepted this charge at the time that the subgroup presented their ideas.) The RTDF team recommends contacting the Interstate Technology Regulatory Cooperation (ITRC) Work Group to assist in gathering information for the survey. (ITRC can be contacted through: Brian Sogorka [609-633-1348]). Once a year, ITRC has a budget meeting and forms subgroups to address specific technologies. RTDF team members did not know when ITRC's annual allocation of funds takes place.

Before the next RTDF meeting, the subgroup plans to initiate all four of the above-listed efforts, update each other on their progress, discuss problems encountered via e-mail, and meet as necessary. By 1999, the subgroup plans to release a draft summary paper for a journal such as "Ground Water Monitoring and Remediation." At this time, the subgroup is planning to address only surfactant flushing technologies because there are currently no proponents of cosolvent flushing in the subgroup, nor have the cosolvent recovery technologies been identified or developed. The subgroup would be willing, however, to expand the scope of the study if representatives for this technology join the subgroup. The summary paper will incorporate the information gathered for the four goals and will identify the best approaches for conducting an economic analysis.

The RTDF team asked the subgroup to consider site characterization costs in their economic analyses. These costs are usually not included in economic analyses, even though most flushing teams have to perform additional site characterization when they arrive at a site. Participants agreed that initial characterization studies are typically "woefully inadequate" to accurately define NAPL plumes or properly design an in situ flush. Accurately defining the location of NAPL is crucial because it ensures that money is not wasted flushing non-polluted areas.

Endpoint Assessment/Technical Performance Criteria
Subgroup Leader: Backup Subgroup Leader: Other Participants:	George Losonsky, IT Corporation Randy Parker, EPA Ken Moor, Idaho National Engineering & Environmental Laboratory (INEEL) Bill Rixey, University of Houston Stephen Shoemaker, E.I. DuPont DeNemours & Company, Inc. Richard Steimle, EPA TIO Richard Willey, EPA

Questions That Need To Be Addressed

After brainstorming and generating a long list of questions that need to be addressed, the subgroup distilled their questions into four categories:

• What is the target endpoint and how do we assess meeting it? Subgroup members acknowledged that there are a variety of targets to choose from. For example, the goal of an in situ flush could be to:

  • Reach a specific environmental guideline (e.g., maximum contaminant levels).

  • Reach a water and soil concentration that does not pose a significant health risk at compliance points.

  • Remove the contaminant source.

  • Serve as part of a treatment train (e.g., in situ flushing could be used to remove a source and then other technologies, such as pump and treat or natural attenuation, could be used for plume reduction).

• What should the target be? Subgroup members acknowledged that the target could be different for different sites. The group believes that the targets should be:

  • Viewed within the context of a risk management framework for the particular site. In general, the entire RTDF team thinks that in situ flushing technologies should be viewed as an alternative within the context of a set of remedial actions designed to achieve effective risk management. Some participants thought that enhanced or intrinsic bioremediation could serve as a good followup treatment. It is unclear, however, to what level in situ flushing would have to reduce NAPL in order for bioremediation to be efficient. If the bioremediation group can identify source area contaminant concentrations at which bioremediation will be effective, this could serve as a target for the in situ flushing technologies. Although many participants were excited about the idea of using bioremediation as a followup to in situ flushing, others warned that researchers will need to determine how the introduction of a surfactant impacts biodegradation processes before more useful predictions can be made.

    Potential users will need to understand that in situ flushing technologies are not likely to achieve complete aquifer restoration as a stand-alone treatment and are designed to remove NAPL rather than to achieve compliance with drinking water standards.

  • Tied to risk-based endpoints

  • Based on assessment of impacts on the whole system

• How can one predict the benefits of in situ flushing? The subgroup identified two tiers of activities that can be performed to predict the benefits of choosing in situ flushing technologies as a remedial option. Activities in the first tier include analyses of:

  • Cost-benefit. Tools are needed to allow potential users to evaluate the cost of flushing versus the predicted benefit in reducing the overall cost of managing risk at the site. The subgroup members believed such tools are key to the technology becoming accepted in the remediation community.

  • Data collected from field tests

  • Laboratory testing

  • Transport modeling (e.g., partitioning interwell tracer test [PITT] and sitewide modeling)

  • Comparison with other alternative remediation technologies (e.g., conventional technologies and other innovative technologies)

  • Site characteristics. To accurately predict how successful in situ flushing technology will be at a given site, the researchers must have a thorough understanding of the source term and the site's geology.

    Activities in the second tier include analyses of:

  • Pilot tests

  • Tests from representative sites

  • Decision trees

  • Key parameters

  • Laboratory tests (e.g., tests for interfacial tension and permeability reduction)

• How can one predict/prevent the potential negative outcomes (e.g., mobilization of pollutants into a previously uncontaminated area) that are associated with in situ flushing? The subgroup suggested that the potential downside of in situ technology can be predicted/prevented if:

  • The site is thoroughly characterized (e.g., the researcher has a thorough understanding of the interfacial tension at the site).

  • The transport mechanisms and the hydraulics of the area are clearly understood.

  • The area being flushed is thoroughly contained either via hydraulic or physical controls.

  • The zone targeted for flushing is clearly defined and monitored.

  • The flushing agent is nontoxic or has regulatory acceptance.

  • Researchers have a data collection framework in place that allows them to identify potential or real problems.

The subgroup also noted that it is important that the public be informed of potential negative outcomes. If the public is hesitant to accept the use of in situ flushing technologies, a comparison of the liabilities associated with other technologies may help alleviate concern.

Future Subgroup Activities: Goals, Strategies, and Schedules

The subgroup identified three objectives:

• Develop a position-statement document providing guidelines for establishing target endpoints. The subgroup envisions this document as conceptual and generic. Bill Rixey has been assigned to produce an outline for the guidelines. The document will provide guidelines to determine acceptable endpoints for:

  • Contaminant concentrations

  • Surfactant concentrations. Some residual surfactant will remain in the soil after flushing activities are complete. In general, people agree that the concentration of the residual surfactant should be less than the critical micelle concentration (CMC).

• Develop protocol/guidelines for predicting our ability to:

  • Reach target endpoints.

  • Identify potential negative outcomes.

    Richard Willey has been assigned to create an outline for the protocol/guidelines.

• Develop a framework for performance assessment. Mr. Shoemaker has been assigned to create an outline for the framework.

This subgroup is considering using contractors to write a first draft of each of the above-listed documents. Mr. Steimle noted that contractual support is available.

Technical Practices/Protocol

Subgroup Leader: Other Participants:

Gary Pope, University of Texas Thomas Early, Oak Ridge National Laboratory Carol English, Cytec Industries Stephanie Fiorenza, Rice University Anthony Holder, Rice University C. Wayne Ives, New Hampshire Department of Environmental Services Richard Jahnke, Lubrizol Corporation Clarence Miller, Rice University Mike Shook, INEEL Randall Sillan, University of Florida A. Lynn Wood, EPA Kathleen Yager, EPA TIO S. Laura Yeh, Naval Facilities Engineering Service Center (NFESC)

Future Subgroup Activities: Goals, Strategies, and Schedules

The subgroup plans to create a living up-to-date technical guide on both best practices and technology needs. The Technology Practices Manual (TPM) written by the Advanced Applied Technology Demonstration Facility (AATDF) will be used as a resource and a point of departure for this technical guide. The subgroup plans to place their technical guide on the Internet so that the document can be updated by the group and linked to the TPM and other source documents. The guide will be separated into two volumes. Volume I will address "What we know now" and will be targeted for regulators and contractors. Volume II will address "What we still need to do" and will be targeted to researchers. At this point, the subgroup plans to focus only on surfactant and cosolvent flushing technologies, but will consider including other types of flushing agents if proponents of these technologies join their subgroup.

The subgroup drafted the following preliminary outlines for both volumes of the technical guide:

Volume I. Protocol

1.0	Description of Technology
1.1	Screening
	1.1.1	Site Parameters. This section will discuss how to evaluate whether a site is an appropriate candidate for in situ flushing.
	1.1.2	Preliminary Cost Estimating/Budgeting. The subgroup plans to coordinate with the "Economic Assessment and Remedial Agent Recovery/Reuse" subgroup for this section of the document.
1.2	Conceptual Approach (e.g., phased site characterization, phased surfactant/cosolvent flushing events)
1.3	Site Characterization
1.4	Design Processes. The subgroup plans to refer to the AATDF TPM for assistance with this section of the document.
	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. This section will provide a discussion of completed projects and lessons that have been learned.
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 Treatment Train
	1.3.5	Application to Other Compounds (e.g., polychlorinated biphenyls)
	1.3.6	Numerical Modeling
1.4	Recommendations

The subgroup has identified several short-term goals:

• Coordinate with other subgroups

• Tighten the definition of the product goal and audience needs.

• Develop a production schedule.

• Expand participation base to include more experts within technical areas.

• Continue making revisions to the above-listed outlines for Volumes I and II.

• Identify task assignments.

Future Subgroup Activities: Goals, Strategies, and Schedules

The subgroup identified two goals:

• Develop a hypothetical full-scale in situ flushing design that will serve as a model for others to use. As part of this goal, the subgroup will:

  • Review AATDF's detailed design plans for the demonstrations conducted at Hill AFB.

  • Write a document outlining steps involved in the full-scale design process and significant issues.

  • Provide a mechanism for additional site designs to be made available on the RTDF Web site.

• Identify a full-scale design project in which the RTDF subgroup might serve in an advisory role. As part of this goal, the subgroup will:

  • Search for sites that might qualify as one of the first full-scale remediation studies.

  • Establish a relationship between those conducting projects and the RTDF subgroup.

  • Provide positive input into the design process through a review cycle.

  • Make frequent reports on the design project's progress, including details of the design, through the RTDF Web site.

TEAM STRATEGY DEVELOPMENT

Coordination Between Subgroups

After the subgroups completed their presentations, the entire RTDF team discussed ways to work together to achieve their team mission. It was noted that there are two ways in which the subgroups can work:

• Compile subgroup documents. Many of the participants in the audience liked the idea of placing the documents on the Internet so that links could be established between the different documents. Some participants thought the different documents should be presented in a series of connecting volumes or as a "suite" of documents.

• Keep the subgroup documents autonomous and separate from each other.

The team did not officially decide which approach they would pursue. It was generally agreed that the subgroups need more time to solidify their ideas before deciding on which option will be the most useful. The team will finalize coordination strategies at the next In Situ Flushing Action Team Meeting.

Activities Planned Before the Next In Situ Flushing Action Team Meeting

The team agreed that the next action team meeting should take place in June or July 1998. Before the group reconvenes, the following should occur:

• Disseminate information more efficiently. As noted by Dr. Annable, cutting-edge information needs to be disseminated more rapidly so that it benefits those people who are currently at work on new pilots and demonstrations. In general, the team agreed that the best way to disseminate information (e.g., data and postings of upcoming events) to each other is through the Internet. A Web site has already been established for this group at: http://www.rtdf.org. Once the user dials into this address, they can access the In Situ Flushing Action Team's Web site by clicking on a specific button. If team members want to post information on the Web site, they should contact Carolyn Perroni of Environmental Management Support, Inc. (EMS). (Ms. Perroni's address, phone number, fax number, and e-mail address are provided in Attachment A.) Access to the Web site is currently unrestricted. If a team member wants to post something confidential on the Internet, arrangements can be made to make the information password restricted.

• Subgroups should work on the outlines for their suggested products.

• Subgroup work assignments should be discussed further and be clearly assigned to volunteers.

• The focus of the In Situ Flushing Action Team should be expanded. Participants agree that the goals set forth by the group would be easier to attain with additional representation. Some participants strongly encouraged team leaders to contact proponents of flushing technologies that utilize agents other than surfactants and cosolvents. Ms. Perroni told the group that EMS has a list of 84 people who expressed interest in the In Situ Flushing Action Team. These people can be contacted to ascertain their interest in more active involvement in the subgroups and may also provide a resource through which individual subgroup chairs can seek specific additional expertise needed in their groups.

• A discussion leader from the Bioremediation Consortium should be invited to the next In Situ Flushing Action Team Meeting. Mr. Shoemaker suggested talking to David Ellis from DuPont.

• A Web site format will be designed to enable each of the subgroups to present information on their goals and planned activities in a consistent style. It was agreed that these meeting summary notes will be used as a "springboard" for a template. A format containing the goals/activities information presented at the meeting will be prepared and sent to the subgroup chairs to review early in February prior to posting the information on the RTDF Web site.

• Monthly or bimonthly conference calls will be set up between the team co-chairs (Dr. Wood and Mr. Shoemaker) and the subgroup team leaders (Dr. Harwell, Dr. Losonsky, Dr. Pope, and Dr. Annable). The conference calls will be organized by EMS and Eastern Research Group, Inc. Each call will have a 1-hour time limit.

Suggested Format for the Next In Situ Flushing Action Team Meeting

Dr. Wood asked the participants for feedback on the format of the first and second team meetings. In general, the participants liked having a mix of talks and group activities. Some thought that more time should be dedicated to subgroup meetings. One member suggested allowing subgroups to meet in the morning, reconvening the entire team in the early afternoon, and then allowing the subgroups to meet again in the late afternoon.

PROPOSED DNAPL REMEDIATION FIELD DEMONSTRATION EFFORTS

Savage Well Site, New Hampshire
Mr. Richard Willey, EPA
Mr. Mike Shook, INEEL

The Savage Well site is located in Milford, New Hampshire. Mr. Willey provided information on site background and Mr. Shook gave a presentation on a neutral buoyance demonstration that is planned in the near future.

Site Background

Ground water in Milford, New Hampshire is contaminated with DNAPL compounds. Contaminated ground water has migrated over a mile downgradient, has resulted in the shutdown of the Savage Municipal Well, and has impacted a supply well at a trailer park. Contaminants have also been detected in the vicinity of private and state fish hatcheries on both sides of the Souhegan River.

Site characterization studies indicate that the horizontal and vertical distribution of contaminants has shifted dramatically over the years due to changes in pumping patterns in the area. The most recent characterization studies utilized data from vertical profiling and permanent monitoring wells. Although these data have been very useful, there is still only a generalized description of the contaminant source.

The Record of Decision and subsequent consent decree that have been issued for the Savage Well site divide the area into two sections:

• The OK Tool source area, which includes the building and the downgradient area within 800 feet of the building. The federal and state governments are responsible for remediating the OK Tool source area, and must attain source control within a specified time frame.
• The remainder of the extended dissolved plume, which is the responsibility of the potentially responsible parties.

Three potential DNAPL locations have been identified at the OK Tool source area. Site characterization studies indicate that depth to bedrock is variable, and that the till is discontinuous. A slurry wall, coupled with soil vapor extraction and hydraulic control within the walled-off space were selected for source containment and treatment. Subsequent to remedy selection, EPA was approached by INEEL and agreed to use this site for a neutral buoyancy field demonstration. Both EPA and the state believe that removal of DNAPL mass represents the best chance of reducing the time needed for operation and maintenance activities.

Concepts Related to Neutral Buoyancy

The concept of surfactant-enhanced aquifer remediation at neutral buoyancy (SEAR-NB) was developed in 1995. By solubilizing the more dense DNAPL constituents in a neutrally buoyant microemulsion, vertical migration of the contaminants can be eliminated. A design process that eliminates vertical migration is especially attractive at sites where no capillary barrier exists to restrict vertical movement (such as the Savage Well Site). Typically, although identically neutral buoyancy can be acheived, it is often considered an impractical overdesign. Instead, negative buoyancy is minimized, and a small degree of vertical migration is allowed. The application of SEAR-NB, then, is to minimize the degree of vertical migration, and to predict the degree of migration expected so that wells can be screened sufficiently deeply to ensure full capture of the contaminant. Three approaches were used in the development of SEAR-NB:

• Theoretical analysis. Researchers have identified four design parameters that can be manipulated to affect the amount of subsurface vertical migration. They are referred to as design parameters because the engineer/operator has some control over their value. These parameters are:

• Numerical modeling. Numerical modeling has shown that vertical migration is predictable on the basis of design parameters and aquifer properties. Nomographs have been constructed for that purpose.

• Laboratory experiments. Using a variety of laboratory experiments (e.g., batch experiments, column experiments, and sand tank experiments), the ability to predict vertical migration as a function of these design parameters was verified.

INEEL's Demonstration At the Savage Well Site

INEEL plans to test the concept of neutral buoyancy with a field demonstration at the OK Tool source area. This site does not have a confining bed to preclude vertical migration. Therefore, a neutral buoyancy flood is considered an attractive option.

Mr. Shook summarized the steps that INEEL is taking to ensure that their demonstration is successfully deployed:

• Conduct laboratory work to identify appropriate chemicals to use for the PITT and flush. Variables that need to be addressed in the laboratory include phase behavior, viscosity, equilibrium rates, adsorption, density, and partitioning coefficients. INEEL plans to use the following chemicals in their demonstration: 1-propanol, 1-hexanol, 1-heptanol, 2-ethyl-1-hexanol, MA-80, and isopropanol. Additionally, xanthan gum might be used for mobility control.
• Create a conceptual design. The conceptual design is intended to assist in actual design of the flood, and should address the following questions:

• What is an appropriate well field (e.g., line drive, 5-spot, etc.)?

• What should the pumping rates be?

• How many pore volumes of injectate should be used?

• What contaminant concentrations should be expected in the effluent?

  INEEL is currently in the process of creating a conceptual design.

• Conduct coring and aquifer testing. INEEL plans to complete this task in late summer or early fall of 1998.
• Conduct a PITT to characterize the amount and distribution of the DNAPL. Although evidence indicates that there is tetrachloroethylene (PCE) located under the OK Tool building, its quantity and exact location are unclear. Additional vertical profiling is currently being performed and INEEL plans to perform a PITT in an effort to identify the source term. As noted by Mr. Shook, it may not be economically worthwhile to run the demonstration test if the PITT shows that there is only a small amount of PCE in the ground.
• Develop a design for the neutral buoyancy flood. Creating a design for the neutral buoyancy flood requires information provided by the laboratory tests, well tests, and PITT.
• Deploy pilot flood.
• Treat effluent stream.
• Assess the performance of the pilot. INEEL plans to use a second PITT to assess the performance of their flood. Other performance assessment techniques might also be used.

RTDF team members can keep abreast of developments at the Savage Well site by dialing into the Milford, New Hampshire Web site.

Dover AFB, Delaware
Dr. A. Lynn Wood, EPA
Dr. Michael Annable, University of Florida

Dr. Wood and Dr. Annable provided an overview of the in situ flushing demonstrations that are planned at Dover AFB. This project is being conducted by EPA's National Risk Management Research Laboratory (NRMRL) with funding from the Strategic Environmental Research and Development Program (SERDP). The goal of the project is to compare enhanced in situ extraction technologies for removal of NAPL at two field sites (one light nonaqueous phase liquids [LNAPL] site and one DNAPL site) using side-by-side demonstrations. Hill AFB was chosen as the LNAPL site and the Ground-Water Remediation Field Laboratory (GRFL) at Dover AFB has been chosen as the DNAPL site. Activities at Hill AFB are nearing completion (i.e., all field work activities have been completed, researchers are completing technology performance assessments for the different test cells, and EPA will start comparing the results attained at the different test cells in the near future). Activities at Dover AFB are just getting underway.

Dover AFB is located in a permeable silty sand formation with a clay-rich aquitard at approximately 40 feet below the surface. The natural water table is approximately 20 to 25 feet below the ground surface and the natural hydraulic gradient is relatively flat. The NRMRL has installed two hydraulically isolated test cells and plans to perform about 6 demonstrations at Dover AFB. The first demonstration will be led by the University of Florida (under Dr. Annable's direction) and will be a cosolvent flush. The aim of this first demonstration, therefore, will be to solubilize contaminants rather than to mobilize them. The University of Florida plans to conduct a single phase microemulsion (Windsor Type I system) flush in the future.

Unlike that of Hill AFB, the ground water in the proposed test location at Dover AFB is not contaminated. DNAPL (i.e., PCE) will be released into the test cells and then recovered via in situ flushing technologies. The DNAPL release strategy is currently in place, but EPA is awaiting regulatory approval for their plan. Upon issuance of a regulatory permit, the demonstrations will go forth as follows:

• Release a known amount of PCE to the test cell. PCE will enter the test cells through preinstalled locations. EPA will create a nonuniformly-distributed plume by releasing different amounts of PCE in the different locations. Demonstration teams will not be told how much PCE was released at the injection points. Some challenges include:

  • Placing the DNAPL within the test cell so that it is equivalent to a site which has "aged" for several years.

  • Placing the DNAPL in the test cell without allowing any significant portion to rest on the aquitard interface.

  • Overcoming difficulties that are associated with unstable flow conditions during placement.

• Characterize the hydrodynamics and the DNAPL mass and distribution in the test cell. As described by Dr. Annable, the University of Florida team will use information provided from initial aqueous dissolution tests, a PITT, and inverse modeling to characterize the plume. Because EPA will know release locations and the total mass released, this exercise will help researchers determine how well their tests predict the location of DNAPL.

• Design an extraction test. Researchers will use bench-scale tests and cell characterization tests to determine the best flushing design for the test cell. Dr. Annable's team has started to do some laboratory work to identify which cosolvent should be used in the cosolvent flush. Some of their tests have analyzed how much PCE solubilization can be achieved using different alcohol mixtures. Some column studies have shown that 99 percent of PCE can be removed when 4-pore volumes of 100 percent ethanol are used. Dr. Annable's team has already started thinking about what well formations will be used. At this point, they are leaning toward using a 5-spot well pattern.

• Perform the flush.

• Determine the mass and distribution of DNAPL in the test cell after extraction. As noted by Dr. Annable, the University of Florida team will use a PITT to determine how much DNAPL remains in the test cell.

• Assess the flushing technologies performance. As noted by Dr. Annable, the University of Florida team will perform a contaminant mass balance once all the data have been collected. The mass balance calculations should be more accurate than those performed at other sites because the initial volume of PCE will be known.

• Compare performance with other techniques, including conventional techniques (e.g., pump and treat).

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

Mr. Warner of Levine*Fricke*Recon (LFR) described a cosolvent flushing demonstration that is planned at Sage's Dry Cleaners in Jacksonville, Florida. The pilot project is being sponsored by the state of Florida and supported by tax money collected from dry cleaning companies. To date, LFR has completed a contamination assessement of the dissolved PCE at the site using data collected from direct push soil borings and from existing monitoring and supply wells. Mr. Warner realizes that a DNAPL source area characterization study (or studies) will need to be performed before the pilot flush is deployed.

LFR plans to use hydraulic controls in the test area (an area 15 feet in diameter and 5 feet deep). The system will involve one injection well and three extraction wells, the latter of which will pump at twice the rate of the injection well. The team (University of Florida, Florida Department of Environmental Protection [FDEP], LFR) plans to use ethanol as a flushing agent. LFR is currently writing the plans for their project and hopes to kick off the demonstration in April 1998.

Mr. Warner also mentioned that LFR is hoping to conduct a surfactant flushing pilot in the near future at an FDEP Dry Cleaner Program Site. This test may be implemented in the fall of 1998.

Environmental Security Technology Certification Program at Camp Lejeune, North Carolina
Ms. Laura Yeh, NFESC

Ms. Yeh is working on an in situ flushing project funded by the Department of Defense (DOD)'s Environmental Security Technology Certification Program (ESTCP). The parties involved on this project are the Navy (NFESC, Port Hueneme, California); EPA (NRMRL in Cincinnati, Ohio and Ada, Oklahoma); University of Texas, Austin, Texas (Gary Pope's Group); and the University of Oklahoma, Norman, Oklahoma (Jeff Harwell and others). While SERDP focuses primarily on technical issues, ESTCP focuses on implementation issues as well. The main goals of the project are to:

• Show that recovery and reuse of surfactants is technically feasible. Originally, Ms. Yeh's team planned to use a two-step process to recover surfactant:

  • Pervaporation. This technology separates DNAPL from the surfactant.

  • Micellar-enhanced ultrafiltration (MEUF). This process reconcentrates the surfactant. (The surfactant becomes quite diluted when it is in the subsurface.)

    As will be noted below, the team is now considering using other recovery technologies.

• Identify surfactants that are conducive to recovery projects.

• Show that recovery and reuse of surfactants is economically feasible. As noted earlier, recovery and reuse of surfactants dramatically impact the cost of in situ flushing technologies. As part of the team's economic analysis, they will set up a controlled pump and treat system at the site so that they can compare the costs generated with pump and treat versus in situ flushing technologies.

• Show that there are a broad range of sites that could benefit from in situ flushing technologies. Hill AFB is regarded as having ideal conditions because it has very permeable soils and a very thick clay barrier. Ms. Yeh hopes to show that the technology works in sites that do not share these "ideal" conditions.

• Receive regulatory permission to reinject surfactants that still have some DNAPL attached to them. Ms. Yeh pointed out that it is not economically feasible to try to achieve 100 percent separation between surfactants and DNAPLs.

After a lengthy search, Ms. Yeh's team chose Camp Lejeune in North Carolina as the site for their demonstration project. Initial site characterization was initiated in July 1997 and was split into two phases. During Phase I, which involved a geoprobe investigation, the team located DNAPL. Phase II involved installing wells for a pump test. Additional site characterization studies were conducted in November 1997. Representatives from Camp Lejeune were surprised to learn that their site was extensively contaminated with DNAPL. Although site characterization studies had been conducted in the past, none of the wells had been deep enough to find the DNAPL. The facility is very interested in the work that Ms. Yeh's team is conducting and have discussed the possibility of making the test pilot area larger than originally anticipated.

In December 1997, Ms. Yeh's team installed the wells for the tracer tests and surfactant flushing demonstration. The well formation includes three injection wells, six extraction wells, and two wells that will be used for hydraulic control. As advised by Dr. Pope, the team is now considering installing two additional hydraulic control wells. Additionally, three wells were installed to remove free-phase DNAPL.

Activities planned for the future include:

• Remove free-phase DNAPL in January and February 1998.

• Run a conservative-tracer test in March 1998.

• Run a pre-flushing PITT in March and April 1998.

• Perform the surfactant flush.

• Perform a post-flush PITT.

To date, the team has encountered several challenges:

• The nature of the DNAPL. Originally, the team had hoped to find a site that was contaminated with trichloroethylene (TCE) because this DNAPL separates fairly easily from surfactants. PCE is the DNAPL located at Camp Lejeune, however, and PCE partitions more readily into the surfactant and is harder to recover.

• Low soil permeability (i.e., 0.5 darcy). Due to the low permeability of the soil, the PITTs and the flushing tests will take a long time to conduct. The PITTs are predicted to take about 40 days to complete and the flushing will likely require 90 days. This time commitment is much greater than that required at Hill AFB, where the flushing demonstration took about 10 to 12 days.

• Viscosity issues and their impact on the choice of surfactant. The team has performed a number of surfactant phase behavior studies in the laboratory. Originally, the team had hoped to use Dowfax 8390 because this surfactant is fairly easy to recover and reconcentrate using pervaporation and MEUF, respectively. Laboratory tests showed that this surfactant was not a viable option, however. Other surfactants that were tested included: MA-80, Tweens (21,80), DNP-18, Glucopon 625FE, and surfactant mixtures such as MA-80/OT and Glucopon 625FE/MA-80. The analysis indicated that MA-80 will work best in the system. Unfortunately, the MEUF system will not work as efficiently with MA-80 as it would with other surfactants. (Ms. Yeh predicts that the recovery system will only be able to recover 70 percent of the surfactant.) For this reason, the team is currently investigating other recovery systems, such as Dr. Harwell's foam fractionation technology.

• Viscosity issues related to the need for cosolvent. Originally, the team had hoped to avoid using alcohol in the flush because cosolvents are not readily recoverable using pervaporation and MEUF. It has become clear that alcohol will be needed. The team currently plans to include alcohol in the flush.

• Peat in the soil. Peat skews the results of PITTs by indicating that there is a spread in tracer curves even when DNAPL is not present.

• The presence of LNAPL. Varsol is located in the upper aquifer; the facility is planning to help remove this. (Cathy Vogel, a representative of the bioremediation technology, has expressed some interest in the Camp Lejeune site. There has also been some conjecture that the varsol may be helping to promote intrinsic degradation of the PCE.)

• High iron concentrations (10 to 25 parts per million [ppm]) in the ground water. High iron concentrations will cause problems with the recovery system.

• Use of calcium chloride (CaCl₂). Tracer studies have shown that 1,000 ppm of CaCl₂ needs to be added to injected solutions to prevent the mobilization of soil fines. If the calcium precipitates as calcium carbonate in the recovery system this will decrease the efficiency of the system.

• Weak capillary barrier at the aquifer/aquitard interface. Although it has not been confirmed, some recent data indicates that there could be a weak capillary barrier. Ms. Yeh's team plans to collect additional data to determine the validity of this recent finding. If the finding is confirmed, this will have a significant influence on design. Participants from the audience were concerned to hear of this potential finding. A few participants are worried that the DNAPL could migrate downward when surfactant is added to the system during the flush. (Downward migration is highly undesirable because there is a drinking water aquifer located beneath.) Audience participants wanted to make sure that the team has thought about the possibility of downward migration. The team is currently considering installing more monitoring wells screened in the aquitard and drinking water aquifer below the test zone so that they will be able to detect any migration when surfactants are added.

Proposed Joint DOD/Department of Energy (DOE)/EPA Demonstration
Mr. Randy Wolf, BDM International Air Force Research Laboratory

Mr. Wolf explained that DOD, DOE, and EPA are working together to identify a site to test DNAPL remediation technologies simultaneously. This team has had considerable difficulty finding a site because they are looking for a site that meets the following criteria:

• Water within 20 feet of the surface
• Clay (confining layer) within 40 feet of the surface
• Has permeable aquifer material (has hydraulic conductivity greater than 10^-4 centimeters/second and does not have cobbles)
• Has an acre of land that does not have buried pipes and other underground cultural features that would limit placement of equipment and/or structural components

The five sites that are being most seriously considered are: Hill AFB, Utah; Cape Canaveral Air Station, Florida; Kennedy Space Center, Florida; Scott AFB, Illinois, and Kelly AFB, Texas. The team would prefer not to pick Hill AFB, simply because so many demonstrations have already been conducted at this site. At this point, the team is leaning towards Cape Canaveral Air Station, because TCE (up to 500 ppm) is the primary contaminant and the site meets most of the desired criteria.

Once a site is chosen, the team will review the candidate technologies and recommend a few innovative technologies to test in side-by-side test cells. In 1995, an Air Force panel cited the following DNAPL remediation technologies as the most promising:

• Steam-enhanced extraction. This technology has been tested at Hill AFB's Operable Units 1 and 2. The principal investigator claims that this technology achieved a removal efficiency greater than 90 percent. Mr. Richard Jackson, Duke Engineering & Services, Inc., was skeptical about the values being reported, noting that the PITTs did not support them.

Mr. Wolf recommended inviting members from PRAXIS Environmental Technologies, the group that conducted the pilot studies at Hill AFB, to the next RTDF meeting. (Mr. Wolf notes that steam-enhanced extraction is a flushing technology, although not a chemical flushing technology.)

• Six-phase soil heating. This technology has been tested at Dover AFB as well as other sites. To date removal efficiencies of 93 to 97 percent have been reported.
• Cosolvent flushing/surfactant injection.

These technologies have been demonstrated by the Air Force, EPA, and numerous universities at Hill AFB Operable Unit 1 and will be demonstrated at the Dover AFB GRFL. At Hill AFB, contaminant revoval efficiencies of 88 percent to 95 percent were achieved. Several attendees suggested that costs for these technologies can be drastically reduced (perhaps to less than $50 per cubic meter) if the flushing fluids are recycled.

In addition to the mass-removal technologies listed above, DOE will also select several of its in situ destruction technologies for consideration in the joint demonstration.

Once the site is chosen, an expert panel will be convened to choose which technologies should be tested. The panel may choose one, two, or three of the above-listed technologies, or may decide on another type of innovative technology. Due to cuts in technology funding, newer innovative technologies that are not as far advanced as the three above-listed technologies are not likely to be chosen. The group hopes to have the site and the technologies chosen by the next RTDF meeting.

Results of Surfactant and Partitioning Interwell Tracer Test at Louisiana Site
Dr. George Losonsky, IT Corporation

Dr. Losonsky described a pilot project that he performed near the gulf coast of Louisiana. He may be contacted for information (see Attachment A).

OTHER DEMONSTRATION SITES

Mr. Steimle asked the participants for the names of new demonstration projects that are getting underway. The audience listed the following locations:

• McClellan AFB, California

• A site in Paducah, Kentucky

• A site at Pearl Harbor, Hawaii

• A site near Grand Rapids, Michigan

• A site in France

ATTACHMENT A
In Situ Flushing
Action Team Meeting

Sheraton Grand Hotel
Irving, TX
January 7­8, 1998

Final Attendee List

Michael Annable Assistant Professor University of Florida 217 Black Hall Gainesville, FL 32611-2013 352-392-3294 Fax: 352-392-3076 E-mail: manna@eng.ufl.edu Steve Byrne Regulatory Services Manager Cytec Industries 1300 Mt. Kemble Avenue Morristown, NJ 07960 973-425-8406 Fax: 973-425-0185 E-mail: steve_byrne@gm.cytec.com Thomas Early Senior Development Staff Oak Ridge National Laboratory Bethel Valley Road - Building 1509 P.O. Box 2008 (MS 6400) Oak Ridge, TN 37831-6400 423-576-2103 Fax: 423-574-7420 E-mail: eot@ornl.gov Carl Enfield Senior Research Scientist National Risk Management Research Laboratory U.S. Environmental Protection Agency 26 West Martin Luther King Drive (MS 235) Cincinnati, OH 45268 513-569-7489 Fax: 513-569-7571 E-mail: enfield.carl@epamail.epa.gov Carol English Cytec Industries P.O. Box 31 Linden, NJ 07036 908-862-6000 Fax: 908-862-4163 E-mail: carol_english@wa.cytec.com Bart Faulkner Environmental Engineer Subsurface Protection and Remediation Division Robert S. Kerr Environmental Research Center U.S. Environmental Protection Agency P.O. Box 1198 Ada, OK 74820 405-436-8530 Fax: 405-436-8582 E-mail: faulkner.bart@epamail.epa.gov Stephanie Fiorenza Assistant Program Manager, AATDF Energy and Environmental Systems Institute Rice University 6100 Main Street (MS 316) Houston, TX 77005-1892 713-527-4725 Fax: 713-285-5948 E-mail: fiorenza@rice.edu Jon Ginn Technical Project Manager U.S. Air Force - OO-ALC/EMR 7274 Wardleigh Road Hill AFB, UT 84056-5137 801-775-6894 Fax: 801-777-4306 E-mail: ginnj@ hillwpos.hill.af.mil 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 Anthony Holder Research Scientist Environmental Science and Engineering Rice University 6100 Main Street (MS 317) Houston, TX 77005 713-527-4977 Fax: 713-285-5239 E-mail: anthony@rice.edu C. Wayne Ives Hydrogeologist New Hampshire Department of Environmental Services 6 Hazen Drive Concord, NH 03301 603-271-2890 Fax: 603-271-2456 E-mail: wives@deswmsf.tiac.net Richard Jackson Manager, Geosystems Duke Engineering & Services, Inc. 9111 Research Boulevard Austin, TX 78750 512-425-2017 Fax: 512-425-2099 E-mail: rejacks1@duke-energy.com Richard Jahnke Technology Manager, Commerical Development Lubrizol Corporation 29400 Lakeland Boulevard Wickliffe, OH 44092-2298 440-943-4200 Fax: 440-944-6847 E-mail: rwj@lubrizol.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 Project Manager IT Corporation One Lakeshore Drive - Suite 1810 Lake Charles, LA 70629 318-436-3606 Fax: 318-436-3244 E-mail: glosonsky@itcrp.com Donald Lowe Assistant Program Manager DoD/AATDF Energy and Environmental Systems Institute Rice University 6100 Main Street (MS 316) Houston, TX 77005-1892 713-737-5745 Fax: 713-285-5945 E-mail: dlowe@ruf.rice.edu Clarence Miller Professor Department of Chemical Engineering Rice University 6100 Main Street (MS 362) Houston, TX 77005-1892 713-527-4904 Fax: 713-285-5478 E-mail: camill@rice.edu Ken Moor Scientific Specialist Environmental Assessment Technology Idaho National Engineering and Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83401 208-526-8810 Fax: 208-526-0603 E-mail: ksm@inil.gov Randy Parker Environmental Engineer U.S. Environmental Protection Agency 26 West Martin Luther King Drive Cincinnati, OH 45268 513-569-7271 Fax: 513-569-7143 E-mail: parker.randy@epamail.epa.gov

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 Bill Rixey Assistant Professor Department of Civil and Environmental Engineering University of Houston Cullen Engineering Building 4800 Calhoun Houston, TX 77204-4791 713-743-4279 Fax: 713-743-4260 E-mail: srixey@uh.edu Richard Schoenfeld Commerical Development Lubrizol Corporation 29400 Lakeland Boulevard Wickliffe, OH 44092-2298 440-943-4200 Fax: 440-944-6847 E-mail: rwsc@lubrizol.com 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 & Environmental Laboratory P.O. Box 1625 Idaho Falls, ID 83415-2107 208-526-6945 Fax: 208-526-0875 E-mail: ook@inel.gov Randall Sillan Hydrologic Sciences University of Florida 2169 McCarty Hall Gainesville, FL 32611 352-392-1951 Fax: 352-392-3902 E-mail: rksi@gnv.ifas.ufl.edu Richard Steimle Hydrogeologist Technology Innovation Office U.S. Environmental Protection Agency 401 M Street, SW (5102G) Washington, DC 20460 703-603-7195 Fax: 703-603-9135 E-mail: steimle.richard@ epamail.epa.gov 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 Engineer Southeast Region Levine*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 Randy Wolf Environmental Engineer BDM International Air Force Research Laboratory, Airbase and Environmental Technology Division 139 Barnes Drive - Suite 2 (AFRL/MLQE) Tyndall AFB, FL 32403-5323 850-283-6187 Fax: 850-283-6064 E-mail: randy_wolf@ ccmail.aleq.tyndall.af.mil Lynn Wood Soil Scientist Subsurface Protection and Remediation Division Robert S. Kerr Environmental Research Center U.S. Environmental Protection Agency P.O. Box 1198 Ada, OK 74820 405-436-8552 Fax: 405-436-8582 E-mail: wood.lynn@epamail.epa.gov 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: lyeh@nfesc.navy.mil RTDF logistical and technical support provided by: Christine Hartnett Eastern Research Group, Inc. 2903B Robinson Avenue Austin, TX 78722 512-474-5746 Susan Brager Murphy Conference Manager Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02173-3134 781-674-7347 Fax: 781-674-2906 E-mail: sbmurphy@erg.com Carolyn Perroni 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 Laurie Stamatatos Conference Coordinator Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02173-3134 781-674-7320 Fax: 781-674-2906 E-mail: lstamata@erg.com