SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
IN SITU FLUSHING ACTION TEAM MEETING
Sheraton Grand Hotel
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:
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:
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:
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:
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.
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|
|1.1.2||Preliminary Cost Estimating/Budgeting|
|1.2||Conceptual Approach (e.g., phased site characterization, phased surfactant/cosolvent flushing events)|
|1.4.3||Facilities Design (e.g., well construction and placement)|
|1.6||Implementation/Regulatory Issues (e.g., injection well permitting/regulatory issues with disposal)|
|Volume II. Technology Needs|
|1.0||State of the Art|
Technology Limitations (e.g., fractured bedrock)
|Site Characterization (e.g., innovative dense nonaqueous phase liquids [DNAPL] detection technologies)|
Access Limitations (e.g., buildings)
|1.3.4||Integration with Other Technologies in a Treatment Train|
|1.3.5||Application to Other Compounds (e.g., polychlorinated biphenyls [PCBs])|
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.
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:
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:
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
in defining performance)
|Why should the data be collected?||Matrix|
|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|
|DNAPL entry pressure (capillary desaturation curve)||B||Primary||DP,SC||soil,water|
|Surfactant Phase Behavior||B,D,A||Primary||DP,CM||water|
|Major Ions (cations [Ca, Mg, Na, K, Fe] and anions [SO4-, HCO3-, Cl-, CO3-, NO3-])||B,D,A||Primary, Secondary||SC,DP||water|
|Total petroleum hydrocarbon (TPH)||B,A||Secondary||SC,CM||water,soil|
|DNAPL degradation daughter products||B,A||Secondary||SC||water|
Dr. Losonsky noted that the Subgroup plans to construct parameter response curves in the future.
Dr. Losonsky said the Subgroup was unable to tackle Task III during the breakout meetings. As part of this task, the Subgroup plans to:
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
4. Steam strip
5. Vacuum extraction
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
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:
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:
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:
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:
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:
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:
Conversely, Dr. Ellis noted that surfactants can also exert negative effects on bacterial populations by:
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:
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:
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
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:
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:
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:
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:
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 Tiedjefor 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.
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:
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:
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:
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:
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:
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:
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.
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.
Final Attendee List
Action Team Meeting
Sheraton Grand Hotel
September 14-15, 1998
Final Attendee List
C. Wayne Ives
S. Laura Yeh
RTDF logistical and technical
Susan Brager Murphy
Revised Outline for Volume I
|Topic||Assigned Team Members|
|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)
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|
1.5.4 Treatment Engineering
1.5.4..1 Effluent Stream Treatment
Air-stripping + carbon (off-gas)
Liquid/liquid absorption (PCE+ethanol+water)
Rotating shear (VSEP)
Steam reforming (catalytic oxidation)
184.108.40.206 Remedial Agent Recovery/Reuse
|Warner, Pope, Yeh, Pennell, Jahnke|
|1.6 Pilot-Scale Testing
Process considerations (mobility control, etc.)
Facilities construction (tanks, etc.)
|1.7 Performance Assessment|
|1.8 Scale up (Full-Scale Design)
Delineate the extent of the:
Target flush zone
Is the pilot-scale data sufficient for full-scale design?
Variability in media properties
Variability in geochemical properties
Existing well tests adequate
Additional data required to determine the well pattern
New hydraulic well testing
Well pattern selection
Well screen interval
Waste management and reuse
|Annable, Shook, Wood, Sawyer
1.8 Scale up (Full-Scale Design) (continued)