SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
SEDIMENTS REMEDIATION ACTION TEAM MEETING

Regal Riverfront Hotel
St. Louis, Missouri
May 25, 1999

EXECUTIVE SUMMARY

About 30 participants attended the Sediments Remediation Action Team meeting in St. Louis, Missouri, on May 25, 1999. Action Team co-Chair Richard Jensen provided an update of the team's activities and the goals for the meeting. He stated that sediments remediation is an important topic that has received increased attention over the past several years. This increased attention has spurred the team to re-energize their efforts.

The goals for the meeting were to: (1) maintain the team's momentum, (2) touch base with other organizations, (3) move ahead on 2+ programs for self-empowered subgroups, (3) accomplish some work, and (4) agree when to meet again. The meeting featured presentations to promote increased team activity, encourage discussion, and provide an update of ongoing and proposed field demonstrations and pilot projects.

Proposed Activities

John Davis discussed demonstration projects that have been conducted by the Bioremediation Consortium. He encouraged collaboration between the Bioremediation Consortium and the Sediments Remediation Action Team based on their mutual interests and complementary experiences.

Ralph Stahl presented three potential ongoing activities: development of white papers, creation of a compendium listing assessment tools, and contribution to a sediments remediation training game. The white papers, discussed during the January 1999 meeting, would serve as a resource to help identify areas of concern and initiate site discussions. The list of assessment tools would provide information on available sediments remediation technologies, including advantages and disadvantages associated with each technology. Stahl said that he is in the process of developing a sediment remediation game and requested input and comment from meeting participants.

Jensen provided information about site background and funding possibilities for a potential demonstration project at the Brookhaven National Laboratory. This project would assess phytoremediation technologies as applied to contaminated river sediments. Before committing funding or personnel, Jensen suggested, the team should meet with the study scientists and gain a better understanding of the technology and the project. Jensen noted that this project may provide an opportunity to work with other RTDF groups.

John George, a member of the Sediments Management Work Group (SMWG), provided an update of SMGW's activities. Since its inception, the group has worked to create a coordinated approach toward evaluating contaminated sediment sites. The SMWG has produced a series of technical papers and is currently creating a decision tree tool to help investigators evaluate contaminated sediments sites. George stated that, based on their similar goals and objectives, the SMWG and Sediments Remediation Action Team may benefit by forming a working relationship.

Open Discussions

Richard Jensen and Ralph Stahl presented a hypothetical case study to promote discussion. Participants expressed multiple concerns about conducting a pilot study without adequate site characterization. Many participants felt the pilot project would be doomed for failure and would not be appropriate given the limited information available.

Site Updates

Joseph Jersak and John Hull (both of Hull & Associates) provided Action Team members with information about the Aquablok™ capping material and a demonstration project they are conducting in Toledo, Ohio. Jersak also described a successful Aquablok™ project completed at an Army base in Alaska. Aquablok™ is a capping material composed of clay particles "glued" to a gravel core. When hydrated, this material creates a cap across contaminated sediments. Noted benefits, according to Jersak, are that the cap has a very low permeability, the clay may enhance biodegradation, and the clay mimics fine-grained sediments used as habitat by benthic communities. Hull & Associates is scheduled to begin a pilot demonstration project in the Ottawa River near Toledo, Ohio, in summer 1999. The purpose of this project is to assess the effectiveness of several capping materials in preventing contaminant migration and providing a suitable habitat for the benthic community. Jersak mentioned that there may be an opportunity for the Sediments Remediation Action Team to conduct a site visit.

John Smith (of Alcoa, Inc.) provided a site update for a particle broadcasting project in Niagara, New York. Currently, the pilot project is undergoing regulatory review; however, Smith hopes that the project will begin in summer 1999. This project includes installing a thin cap over contaminated sediments in the slow-moving Grasse River. Smith's presentation focused on the technical background of the project and completed and ongoing investigations conducted to support the technology. Alcoa, Inc., has conducted settling column tests, cap stability tests, and contaminant migration tests to assess the applicability of this technology. These studies indicate that particle broadcasting may be an appropriate long-term solution for sediment contamination at this site.

WELCOME, OPENING REMARKS, AND DESCRIPTION OF MEETING OBJECTIVES
Richard Jensen, DuPont Corporate Remediation

Richard Jensen, co-chair of the Remediation Technologies Development Forum (RTDF) Sediments Remediation Action Team, welcomed approximately 30 participants (see Attachment A) to the Sediments Remediation Action Team meeting. (Jensen's co-chair, Dennis Timberlake, was unable to attend this meeting.)

For those new to the group, Jensen began by discussing the previous Sediments Remediation Action Team meetings, including the three meetings in 1996 (in Cincinnati, Ohio; Wilmington, Delaware; and Vicksburg, Mississippi); the September 1998 meeting in Cincinnati, Ohio; and the January 1999 meeting in Washington, D.C. Between 1996 and 1998, the group did not meet, but many events occurred that led group members to believe that the Sediments Remediation Action Team should reconvene. Some of these events, which were discussed at the January 1999 meeting, included:

• Many projects approaching the construction phase.
• Technical activity and focus accelerating in the sediment field.
• The U.S. Environmental Protection Agency (EPA) preparing a report for Congress on contaminated sediments management strategy.
• The National Academy of Sciences (NAS) completing a related study and holding a conference over the summer of 1998.
• EPA working with other agencies to draft user's manuals supporting EPA's sediment remediation strategy. The Sediments Remediation Action Team felt this was an opportune time to meet the regulators and provide input.
• NAS commencing a study on dredging and polychlorinated biphenyls (PCBs). Jensen noted that Timberlake is serving as the EPA program manager for this study.

Minutes of meetings and several conference call can be found on the Web at www.rtdf.org/public/sediment/minutes/default.htm. The overheads that Jensen showed during his opening remarks are included as Attachment B.

After providing a brief overview for new members, Jensen presented the goals of this meeting.

• Maintain the team's momentum.
• Touch base with other organizations. For example, Jensen has been meeting with the RTDF Bioremediation Consortium to discuss ways to collaborate efforts.
• Move ahead on 2+ programs for self-empowered subgroups.
• Accomplish some work. Jensen pointed out that the group is small enough to move forward; discussions of how this should occur were to begin at this meeting.
• Agree to meet again, in either conference calls or "face-to-face" meetings, and discuss dates and locations for future meetings.

To conclude the opening remarks, Jensen presented the meeting agenda and briefly summarized the content of each presentation.

PRESENTATIONS

LINKAGES WITH THE RTDF BIOREMEDIATION CONSORTIUM
John Davis, Dow Chemical Company

As a member of the RTDF Bioremediation Consortium, John Davis discussed the potential for interactions between the Bioremediation Consortium and the Sediments Remediation Action Team. Davis began by presenting an overview of the Bioremediation Consortium, discussing past projects completed by the group, describing potential future projects, and suggesting several ways in which the two groups could work together. The overheads that Davis showed during his presentation are included as Attachment C.

The Bioremediation Consortium was formed in 1993 and includes members such as the Dow Chemical Company, Beak International, Ciba-Geigy Corporation, DuPont, General Electric, ICI Americas, Novartis Zeneca, Inc., the U.S. Air Force (USAF), the U.S. Department of Energy (DOE), and the EPA. The focus of this consortium has been the development, application, validation, and acceptance of technologies for in situ remediation, specifically biotreatment of chlorinated solvents in groundwater. The consortium was originally convened in order to leverage its members' resources. For example, the entire cost of projects has been between $15 and $18 million. However, the Bioremediation Consortium has contributed less than $1 million, and this has been not in true dollars but in "sweat-equity"--several "people years" in work effort every year for the past 4 to 5 years. The consortium has been successful in helping advance the science and application of natural attenuation, and biotreatment in general, as a cost-effective treatment alternative. Over the years, the technology and science have moved forward and the Consortium has been valuable for all the participants. For example, the Dow Chemical Company has been able to use natural attenuation as the remediation alternative at a variety of sites. Davis presented two key reasons why the Bioremediation Consortium has been successful. First, the group established an early focus on a specific technology and specific contaminants. Second, the projects selected have been of mutual interest to all parties within the consortium. Davis noted that these are key points to consider if the Bioremediation Consortium and the Sediments Remediation Action Team decide to work together.

Before discussing the Consortium's current activities, Davis discussed past accomplishments. The Bioremediation Consortium conducted a project at Dover Air Force Base in a series of phases. The overall objective of the project was to remediate contamination, specifically chlorinated solvents in ground water. Phase I was completed over the past 4 to 5 years and focused on dissolved-phase solvents in ground water. Phase I investigations consisted of laboratory and field studies for natural attenuation and accelerated anaerobic bioremediation. Davis felt the studies were a success. The Bioremediation Consortium has produced a series of publications and National Technical Information Service (NTIS) reports, which will be available soon, discussing natural attenuation and accelerated anaerobic bioremediation. In addition, the USAF included natural attenuation in the Record of Decision (ROD) for Dover Air Force Base. A bioaugmentation pilot study, which included adding microorganisms to remediate a small area, was completed and was so successful that the USAF will be implementing this technology as a full-scale project. In addition, companies involved in the Bioremediation Consortium have been able to use data from Dover Air Force Base to support natural attenuation technologies to other sites.

Phase II at Dover Air Force Base is currently in progress and consists of using laboratory and field studies to investigate source areas. A common belief, stated Davis, is that biotreatment is not an effective remediation technology for source areas because contaminant concentrations are too high. Initial Phase II studies, however, have found that this may not be accurate. Currently, the Bioremediation Consortium is selecting test sites for Phase II field studies. One potential site is an industrial site located in Niagara, New York, and the other site is located at Kelly Air Force Base, Texas. The rationale for selecting two potential field study sites, Davis noted, is based on a lesson learned from the Phase I studies: a backup site should always be selected if the site investigations or additional data indicate that the first site does not meet the study parameters. Additional sampling at the Niagara site and Kelly Air Force Base--with preliminary screening in the laboratory--is being conducted for the Phase II study to determine if there is enough biological activity to degrade solvents.

Phases I and II were included in the initial agreement between members. The Bioremediation Consortium operates under a series of formal agreements between the different partners, including a Cooperative Research and Development Agreement (CRADA) with EPA and the Air Force, agreements with the Department of Defense (DOD), and industry subgroup agreements. These agreements serve as formal time and funding commitments from the different participants. Davis stated that the participants have been pleased with the success of the program and have felt that the program has brought value to their organizations. They have therefore been exploring ways to extend their working relationships by extending agreements to include continued Phase II activities and additional Phase III studies.

Davis stated that the mechanisms for extending the Phase II agreements have been completed, but the Phase III activities are still being discussed. The Bioremediation Consortium is working to identify topics of interest and participant commitments. As a first step, the Bioremediation Consortium created a list of potential study topics, two of which were considered areas of key interest. One topic was source reduction of chlorinated solvents in ground water, which is not of specific interest to the Sediments Remediation Action Team. The other topic was sediments remediation, with a particular focus on the sediment-groundwater interface (many Consortium members are working at sites where ground water is passing through sediment) or use of assessment tools (such as the protocol for natural attenuation). Davis presented an excerpt from minutes of a Bioremediation Consortium meeting in which these ideas were discussed. The Consortium felt there should be a focus on solvents because their experience is with solvents, although they may not be a primary sediment contaminant. The belief was that some of the principles learned from studying solvents could be applied to other contaminants. Davis noted that Consortium members were concerned about the differences between the aquifer sediments and the aquatic sediments, including geochemical, physical, and biological aspects; spatial distribution; and degradation rates.

Davis stated that the Bioremediation Consortium has made a significant effort to examine how to apply natural attenuation to ground water. The Consortium feels some of the ground-water principles may apply to sediment. One reason the members are discussing the possibility of extending ground-water natural attenuation to sediment is the recent directive from the Office of Solid Waste and Emergency Response (OSWER) on the use of monitored natural attenuation at Superfund and Resource Conservation Recovery Act (RCRA) corrective action sites with underground storage tanks. The directive states that "although this directive does not address remediation of contaminated sediments, the principles would be applicable." Davis believes this is an interesting concept and may serve as a basis for interaction between the RTDF groups. The Sediments Remediation Action Team may be interesting in exploring which ground-water principles are applicable to sediments.

To further investigate the potential for forming a working group, David Ellis, a Steering Committee chairperson, invited Jensen to the last Bioremediation Consortium Steering Committee meeting. At that meeting, Jensen informed Consortium members about the Sediments Remediation Action Team's activities. This meeting served to identify ways these groups could provide technical support to each other. Davis felt that beyond technical support, the Bioremediation Consortium has resources and experience that would benefit the Sediments Remediation Action Team. For example, the Bioremediation Consortium established a series of formal agreements for members. If the Sediments Remediation Action Team chooses to use formal agreements, the Bioremediation Consortium agreements could serve as a template. The Bioremediation Consortium also has experience in fund raising--they have raised several millions of dollars for field projects. This means that they have identified who to approach with funding request and who may be interested in the technology. (Davis noted that some of the field projects could not have been completed without funding solicited from the Chlorine Chemical Council or DOE.) The Consortium also has 5 to 6 years of experience in implementing and conducting field studies. The Sediments Remediation Action Team could benefit from applying the lessons the Consortium has learned, (for example, always have a back-up field study site). The Bioremediation Consortium also has experience in gaining public and regulatory acceptance for alternative treatment technologies, which is one of RTDF's objectives. The Consortium has sponsored a natural attenuation training course through the Western Governors Association and the Interstate Technology and Regulatory Cooperation (ITRC). Over 1,000 state regulators have been educated about natural attenuation through this course, which has been so successful that ITRC has asked the Bioremediation Consortium to develop a course on accelerated bioremediation. In addition, the Dutch Organization for Applied and Natural Sciences Research (TNO) would like to translate the natural attenuation course to Dutch for use in the Netherlands.

Davis also presented some ideas for topics or issues that the Sediments Remediation Action Team may explore as they move forward. The group could compare natural attenuation protocols for aquifer sediments to examine how these protocols relate to aquatic sediments. Specific areas of interest may include geochemical, physical, and biological parameters. These parameters are well described for aquifer sediments, but it is unknown how these parameters apply to natural attenuation or natural recovery in aquatic sediments. The group could also examine aquifer and aquatic sediments to identify the key differences. Davis felt that the Sediments Remediation Action Team should begin work by writing technical papers.

At the conclusion of his presentation, Davis volunteered his time and energy to help coordinate a working relationship with the Bioremediation Consortium. Davis believes that natural attenuation as applied to sediments is an area of interest for both groups. The topic was then opened for discussion.

Jensen asked how the Bioremediation Consortium produced their documents. Davis indicated that the Bioremediation Consortium identified 16 documents (seven publications and nine NTIS reports) associated with the Phase I studies. In order to produce these documents, the Consortium divided the document topics into different areas of expertise, such as ground-water chemistry or microbial characterization. Each area was addressed by a 4- or 5-member subgroup, which prepared information and an outline for the topic area. This information was then presented to the Steering Committee to determine funding allocation and document preparation.

To answer a question posed by Jensen about subgroup logistics, Davis responded that most of the Consortium's subgroups meet in conference calls. When possible, the subgroups hold meetings when members are attending conferences or professional meetings. (They do not schedule individual subgroup meetings.) Another participant asked how much time was needed to prepare a document. For the one or two documents that were not based on the laboratory or field studies, Davis indicated, the document was produced within a year of identifying the topic. Most of the documents and reports are based on interpretation and analysis of the laboratory and field data. The Bioremediation Consortium also developed a position paper, which it produced within 8 months. (That paper is available at the RTDF web site, www.rtdf.org.)

Davis noted that the Bioremediation Consortium recognized that other organizations, such as the USAF, are also studying natural attenuation. Therefore, a key concern was to avoid duplicating others' efforts. As a result, the Consortium spent significant effort identifying other investigations.

A participant questioned how appropriate it is to apply the natural attenuation protocol to sediments because contaminated sediments undergo an ecological risk assessment. If risk is identified, then remedial actions are examined. If no risk is identified, then a no-action alternative, essentially natural attenuation, is selected. The participant was especially concerned about the site-specific issues surrounding sediments. Davis agreed that sediments should be examined on a site-specific base, as should ground water, to determine if natural attenuation is an appropriate remedial action. Davis noted the importance of considering site-specific conditions for application to ground water, because at some sites natural attenuation is not occurring in ground water and is not a viable alternative. An investigator should examine site conditions, contaminants of concern, and the site's geochemical, physical, and biological parameters to determine if natural attenuation will occur. The technical justification for natural attenuation needs to be established. Natural attenuation should not be confused with a no-action alternative.

A participant asked if the references to a natural attenuation protocol meant that the Bioremediation Consortium is developing a method for assessing the applicability of natural attenuation. Davis responded that the protocol would list parameters that should be considered when assessing natural attenuation as an option, but would not be a list of steps to follow as a method for assessing natural attenuation.

Another participant asked if the principles of natural attenuation were applicable to both freshwater and marine environments and if differences in these environments have been considered. Davis indicated that the consortium has considered these differences and has mostly focused on freshwater issues. However, Davis is currently working at a site where ground water is entering a marine environment; therefore, both freshwater and marine environments are involved. When evaluating this issue, the Bioremediation Consortium examined differences between high-energy (ocean) and low-energy (lake or river) environments, rather than differences between marine and freshwater environments. The Consortium has not decided upon a focus, but they are tending toward the low-energy environment with the understanding that many of the principles will not apply to high-energy environments. For example, in marine sediments there are sulfate-reducing conditions for microbial activity, whereas methanogenic processes are involved in freshwater sediments.

As a final question, a participant asked if there has been a greater focus on the biological or physical degradation processes. Davis answered that his expertise is in biological process, but he believes that for sediments the physical processes may be as important if not more so. The different impacts of biological and physical process must be recognized when applying ground-water principles to sediments. Davis noted that even the terms "natural attenuation" versus "natural recovery" have different meanings for the different media. Jensen added that there have been discussions of the definitions of bioalteration, biostimulation, and bioaugmentation. These definitions continue to evolve as knowledge of the field grows. Jensen noted that DuPont became involved originally, not because of interest in natural attenuation, but because of interest in biostimulation: its study of natural attenuation arose from that earlier interest. Jensen also commented that one of the catalysts for beginning discussions between the Bioremediation Consortium and the Sediments Remediation Action Team was a DuPont Corporate Remediation site with arsenic in ground water and sedimens. Bioconsortium members thought the biological and geochemical processes occurring within the ground-water-sediment interface could have important impacts. Jensen gave an example of processes occurring at the surface water-sediment interface, mentioning a marine site at which tidal fluctuation is causing sulfate chemistry in the retaining wall, or dike, of a confined disposal facility (CDF) to immobilize metals and prevent contaminant migration.

TOOL FOR SEDIMENT ASSESSMENT TRAINING
Ralph Stahl, DuPont Corporate Remediation

Ralph Stahl presented three topics for discussion: potential white paper subjects, assessment tools and approaches, and a sediments assessment training program. As part of the presentation, Stahl sought comments and feedback from meeting participants. The overheads that Stahl showed during his presentation are included as Attachment D.

The first topic, potential white paper subjects, was also discussed by the Assessment Subgroup at the January 1999 meeting. Stahl presented an overhead listing 13 potential white paper subjects. Such papers are used to initiate discussion about a site, such as data needs or data interpretation. For the Sediments Remediation Action Team, these white papers are intended to support a demonstration project using a hypothetical site. A similar demonstration project using white papers was recently completed by EPA and several trade associations. These organizations created a hypothetical site and provided information on how to complete a risk characterization and risk assessment. One of the products of that project was a set of 1- to 3-page papers designed to identify the important issues in the risk characterization and assessment process. The Assessment Subgroup has not moved forward on creating white papers since the January 1999 meeting; Stahl said he would like to receive commitments from people to move forward on this task, and requested that interested members contact him. A participant asked if the white papers would be internal documents or if they would be distributed. Stahl felt that initially the papers would be for internal use, but that publication is a possibility.

In discussing the second topic, assessment tools and approaches, Stahl asked if it would be possible for the Assessment Subgroup to develop a compendium or listing of assessment tools. Stahl argued, that although this type of compendium may be available already, there has never been a short summary of the assessment tools listing their advantages and disadvantages, application to sediments risk assessments, and application to remedial alternatives. The compendium could also list which tools would not succeed in certain situations or which tools should be used in concert to gain the most valuable results. If possible, general costs could be included. Stahl presented four assessment areas: chemical, biological, physical, and toxicological (this is not an exhaustive list of areas). Stahl stated that, hopefully, the compendium he was proposing could lead to research ideas and studies for RTDF to fund.

Participants provided comments on the proposed compendium and suggested alternative ideas. A useful component of the compendium, as suggested by a participant, would be a list of acceptable technologies for each state. One participant expressed concern that a compendium of assessment tools and approaches would overlap in subject matter with the white papers. Stahl agreed that there may be some overlap, but he believes that the compendium would be a "tangible" product. Another participant noted that many different groups are attempting to create similar compendiums of assessment tools and each group is using a different approach to achieve this task. Perhaps RTDF would be best served, this participant continued, by compiling the compendiums created by other groups. Another participant noted that the Permeable Reactive Barrier Action Team maintains a database of technology profiles in which project descriptions are entered by team members; perhaps a similar database could be created on the Sediments Remediation Action Team's Web site. Another participant noted that the Sediments Management Work Group (SMWG), which operates independently of the Sediments Remediation Action Team, maintains a list of technical papers, but a compendium of assessment tools is absent from this list and may prove valuable as a companion to the technical papers. Stahl stated that his main objective in suggesting the compendium was to prompt the Sediments Remediation Action Team to move forward. Overall, Stahl felt that discussions indicated that there would be some value to generating the white papers and an assessment tools/approach document. The next step would be for the Assessment Subgroup to meet and begin generating these documents.

Stahl said that he discussed creating a sediment assessment game during the January 1999 meeting. He said that the idea for this game developed over the past 2 or 3 years based on another game used to train regulators and organizations how to conduct an ecological risk assessment and why ecological risk assessment is important. This latter game is also used as an outreach tool. For example, several universities use it in their course work to educate students about the many factors considered when addressing contaminated sites. To play the game, a group of people are brought together and presented with a site scenario, either real or hypothetical. Each scenario includes background information, questions to answer, and a set spending limit. To add complexity, unforseen events can be added, such as being sued by the Environmental Defense Fund. As the game is played, people begin to gain an understanding of how to evaluate ecological risk at sites, what information is useful, and how to pay for investigations and remediation. The scenarios can last from 1.5 to 4 hours depending on complexity and time limits. At the end of each scenario, there is a debriefing to discuss results and problem-solving approaches. People with different backgrounds can have very different perspective on how to approach problems. Currently, Stahl and David Hohreiter are adding a sediment module to the game. The goal of the game is to educate people about the many tools available for assessing sediments. Stahl said that team members could help by providing ideas and insight on how to make this game a good training tool and a useful interface between groups with various backgrounds.

In looking at the outline for the sediments scenario, Jensen used the tethered clams study as an example of how sediments remediation is an interdisciplinary topic. He noted that there are great benefits from bringing together experts with different backgrounds. Jensen also commented on the need for good communication between these experts.

In closing, Stahl presented an ecological risk management framework, which was developed as a multi-stakeholder project and appeared in Environmental Toxicology and Chemistry, volume 18 supplement. The risk management framework presents a step-by-step method for making ecologically based risk management decisions, but could apply to human health decisions. This risk management framework is part of a larger risk assessment process, which Stahl did not present. Stahl thought the risk management framework could be a useful tool for the Sediments Remediation Action Team and felt its potential uses and benefits should be discussed. Some of the topics of interest to the Sediments Remediation Action Team, particularly those related to assessment, may apply to more than just the risk management portion of the larger risk assessment process. However, information on potential actions, such as capping and dredging, is also compiled within the risk management framework. Stahl also noted that once a potential remedial action is in place, there is the question of what monitoring is needed to determine the action's feasibility. Stahl noted that the framework is currently missing a feedback loop for reassessment of selected remedies.

ASSESSING BENTHIC RECOLONIZATION AFTER CAPPING
Richard Jensen, DuPont Corporate Remediation
Ralph Stahl, DuPont Corporate Remediation

Jensen and Stahl presented a hypothetical river system site to discuss methods for assessing benthic recolonization after capping. Jensen indicated that this presentation was formatted to encourage interactive discussion between team members. The site defined for the discussion was fresh water riverine, with moderate flow, and with probable ongoing contamination sources of unknown magnitude, including oil and grease.

Jensen asked if members had any experience with test caps in terms of recruiting and sustaining benthic communities. He noted that the Army Corps of Engineers (USACE) has completed many capping projects, but wondered if they have completed benthic community studies. Jensen then requested participant comments and questions.

Several participants commented that conducting a pilot study without fully characterizing the site may be premature. Numerous fundamental questions should be addressed before designing or installing a test bed. What are the contaminants of concern? Are there risk drivers? What is the relationship between contaminant concentrations and the ongoing contaminant sources? Has an ecological link been established between the contaminants of concern and the organisms that are lacking in the benthic community? Physical and geochemical factors, as well as contaminants, can limit the benthic community.

Information on physical characteristics that may affect the cap type (such as the current profile velocity) should be collected. Suspended sediment samples should be collected to determine what is depositing at the site and if these sediments are geochemically and anthropogenically different from the bottom sediments. Unless a historical source is causing ecological damage, a fundamental tenet of site remediation is "do not complete remediation until the source is stopped."

Jensen suggested that a test bed could be used to answer the overall question of success without having to answer all the individual questions, especially if the answers to individual questions would be difficult to reach. Jensen noted that the test bed approach is an example of using a surrogacy tree. Several branches of the tree, in this case, would be skipped in an attempt to answer a general question. If a benthic community could be established in the test bed, knowing why the community was successful might not be necessary. However, if the cap were unsuccessful, then it would be unknown why; the cap might have been unsuccessful in isolating contaminated sediments or ongoing sources might still be affecting the community. If unsuccessful, therefore, experiments would have to start over. Not knowing why a cap was or was not successful would also make it difficult to apply the technology to similar sites. One participant noted that even if a project like this were successful, it would be unknown if the methods used to measure success were appropriate. Without an understanding of the system before the study, the project would be left without an effective means to measures success. This also leads to the question of how long the test beds should be monitored to assess sustainability.

Jensen also speculated that the test bed might serve as an effective means of assessing ongoing sources. One participant suggested using sediment traps first to assess ongoing sources. Jensen asked if there is a sediment trap that could also recruit a benthic community, the parameter of concern. He wondered if a very small test bed (1 to 2 feet in diameter) could serve as a sediment trap and a recolonization study site. Participants noted that there are biological assays to test organisms' willingness to colonize an area. In this hypothetical situation, Stahl agreed that investigators would have tried some tests in the laboratory before commencing field studies.

As further definition, Stahl stated that sources would continue to contaminate the river after capping, and that this might provide a rationale for installing test beds before complete characterization. A participant felt that this provides even more reason to fully characterize the site before conducting a pilot test: source control is a key component of successful capping and site remediation. This participant believes that the pilot test is doomed to fail if contamination is ongoing.

One problem of conducting a pilot study, as noted by a participant, is that the river system is altered without knowing the impacts to the benthic community. Community structure is an opportunistic phenomenon and when the environment changes, either chemically or physically, the community structure will change. Finding a reference site that has the same physical characteristics but lacks contamination may be beneficial in examining community structure. That pristine community could have low diversity and be perceived to be unhealthy. However, the community structure that has evolved there may be the best structure possible based on the physical constraints.

One participant expressed concern about oil and grease content limiting the stability of the sediments and their ability to support a cap. If a cap were constructed, he asked how would the underlying sediments react and would there be sediments migration? Another concern was that if the river is shallow, installing a cap might affect river flow and flooding. More information on these issues should be gathered before installing a pilot bed.

A participant noted that the pilot test may be a good concept, but in practice the parameters selected for testing must be selected very carefully. A river is a dynamic system and is not the final destination for the sediments. A particular section of a river is only a transfer point through which sediments pass as they migrate further downstream. He presented an example of system dynamics, describing the study of sandbars. An important factor to consider is that the sediment within sandbars are always shifting. The first goal in examining a sandbar is to determine how it is moving. The next step is to determine if vegetation can be established, and the final step is to determine if the plants can be used for phytoremediation. If these parameters are known, there is a chance for success. However, if nothing is know about the sandbar, there is a good chance the sandbar will move and the study will fail.

Joseph Jersak stated that his company is preparing to conduct an actual pilot test in northwestern Ohio in summer 1999. The pilot test is being completed under a grant received by the city of Toledo, Ohio. This pilot test will involve applying Aquablok™, a sediment-capping material, to a 3-acre area within the Ottawa River. Hull & Associates has received an USACE permit, but the permit requires study of the impacts of this capping technology on the benthic community. His company is working with the Ohio Environmental Protection Agency (OEPA) to conduct this study, with OEPA assuming the lead in sampling and analyzing the initial data. Some of the questions raised concerning Jensen and Stahl's hypothetical site may be answered by studies at this site. OEPA is using a lacustuary vertebrate index, developed for mixed lacustrine and estuary environments. With qualitative and quantitative sampling, OEPA will determine baseline conditions in the impacted area and, over the course of a 5-year monitoring program, will assess benthic recolonization. The study includes a control area. Several different cap designs are proposed, so community questions over time and cap type can hopefully be addressed. In terms of source control, the primary sources have been addressed. (This has involved closing several landfills and implementing remedial actions.) However, secondary sources, such as contaminated sediments up- and downstream, are not being addressed. Therefore, there will be some opportunity for additional contamination to enter the system. However, Jersak indicated that he would not expect radical changes in the benthic community over the study period and area. Aquablok™ is a bentonite-based material, clay with a gravel core. The bentonite is similar to the fine-grained silts currently present and one objective of the study is to determine if the benthic organisms find Aquablok™ habitable. As a different approach to this question, a participant asked what the remediation objectives are and whether there is a regulatory basis for establishing benthic communities. This participant also expressed concern about a need to study benthic community recolonization. His experience has shown that people feel funds may be spent better elsewhere, especially if there will be ongoing contaminant sources even after a cap is installed. Jensen re-stated the definition, that it is unknown if ongoing sources are substantial enough to preclude recolonization. Another participant noted that this is an important question to answer because there are no longer pristine sediments anywhere. Another question to answer, she continued, is the relative contaminant contribution of different areas. Understanding of the different toxicities or relative impacts of the sediments and the ongoing sources can contribute to achieving the overall goal of net improved ecological environment. Using capping or test beds may be reasonable if areas of high contaminant concentration are being isolated.

Another participant noted that the objectives in this case seem not to be remediation goals, but community restoration goals. This hypothetical case should be approached with some understanding of risk assessment, receptor identification, critical contaminants, and target contaminant levels. It may not be necessary to restore a healthy benthos throughout the whole system, nor possible to address unacceptable contaminant levels in fish tissue. Understanding system interactions, based on a conceptual site model, is fundamental to making any remedial action decisions. As presented here, installing test beds manipulates a system without understanding what the responses will be.

The purpose of the RTDF, as noted by a participant, is to evaluate and recommend remediation approaches. From this discussion, the participant was unsure if the group is attempting to recommend a capping approach without assessing the different aspects of this approach or examining other approaches. Another participant noted that there are very few technologies available for addressing sediment contamination. Capping should be used very carefully. In this hypothetical case, capping would likely be a failure, and the project should not be implemented. As a failure, this might damage the reputation of capping, which may be a very good technology for other sites.

One participant noted that this hypothetical case raised the issue that there are some sites that are so large that dredging or removing contaminated sediments is overwhelming in terms of habitat destruction and cost. At these sites, there may be a feeling that there is nothing to lose by trying alternative technologies in addition to capping. Many technologies should be considered concurrently. Carefully planned approaches are still needed when implementing alternative technologies.

Jensen responded by stating that the intent of this exercise was to ask if a test pilot project is appropriate. The answer from the members seems to be no. Jensen and Stahl were also trying to determine if anybody has done a similar pilot test and to discuss potential concerns. Stahl stated that these discussions indicate that nobody knows of such a project being completed.

Jensen summarized this discussion by stating that there were some interesting concerns raised. There was an overall agreement that conducting pilot tests with small test beds would not be beneficial without additional site information. Participants did not feel the regulators would object to conducting studies as long as the project time frame is not jeopardized.

ANNOUNCEMENT: SEDIMENTS RESEARCH WEB SITE
Mark Hodges, Georgia Tech University

(The overheads that Hodges showed are included as Attachment F). Mark Hodges is involved with a group that transfers technology developed by the Hazardous Substance Research Center, which is sponsored by EPA. Hodges spoke to the group to notify participants of a project of potential interest. His group has created a sediments research community at the Web site http://maven.gtri.gatech.edu/sediments/. The project is intended to facilitate interactions between practitioners and researchers and to serve as another information resource about contaminated sediments. Currently, the Web site is a shell which includes: (1) a list of individuals working in the contaminated sediments area with pertinent professional information; (2) an introduction to contaminated sediments with summaries of the state of the art and research problems in several key areas; (3) an online library of articles, proceedings, and reports; (4) a page with links to other resources on the Web; and (5) a bulletin board of events and other information of interest. A list-serve (Internet newsgroup) will be created in the future for discussion of various topics. Hodges requested that participants review the site and provide feedback. Currently, the development of the site is in the early stages, but will grow as members add information. Hodges invited RTDF members to submit their own professional information to the site and contact him at (404) 894-6987 or mark.hodges@gtri.gatech.edu with questions or comments.

AQUABLOK™ IN SITU TECHNOLOGY AND THE POSSIBILITY OF A FIELD VISIT
Joseph M. Jersak and John Hull, Hull & Associates

Joseph Jersak and John Hull are both with Hull & Associates, Inc. (HAI). HAI provides technical support to further the Aquablok™ in situ capping technology. In discussing the Aquablok™ technology, Jersak quickly defined the extent of the contamination problem nationally, the different approaches for addressing contaminated sediments, and the recommended functions of an in situ cap, per ARCS guidelines. He also described the Aquablok™ technology and demonstrated how it can meet capping requirements, how it has been successfully used in a tidally influenced wetland ecosystem, and how it can be integrated into typical capping project. Overheads used during Jersak's presentation are included in Attachment G.

Nationally, over 1 billion cubic yards of sediments have been impacted by contamination, based on the EPA documents produced last year. Contaminants include PCBs, pesticides, and metals at concentrations that could affect human and ecological receptors. In terms of spatial extent, areas of probable concern (regions where contaminants are at or near risk levels) compose approximately 5% of the watersheds across the United States. Most of these sites are located in the Northeast and Midwest (including around the Great Lakes). Jersak noted that there are about as many freshwater inland sites among these as there are brackish or saltwater coastal sites.

Historically, sediments remediation techniques have included natural attenuation or recovery, removal and treatment (dredging), containment or treatment in place (chemical injections, promoting biodegradation), and in situ capping. Historically, sandy materials have typically been used for in situ capping for many reasons: relative availability, ease of distinguishing between the cap and sediment material, and past success. The primary functions of a cap, as defined in EPA's ARCS guidance document are: (1) physical isolation of the sediment from the benthic environment; (2) stabilization of contaminated sediments, thus minimizing their transport and redistribution (this essentially addresses cap integrity in an erosive environment); and (3) reduction of dissolved contaminant movement up through the sediments, into the benthic community, and finally to the overlying water column.

To describe how Aquablok™ meets these three capping functions, Jersak presented background information about this technology. Aquablok™ is a composite clay mineral-based material with a gravel core. The clay material is primarily bentonite and an organic polymer is used to "glue" the clay to the gravel core. Bentonite is used for its reactive and hydrating properties, which cause it to swell upon wetting. Aquablok™, which handles like gravel when dry, is installed by depositing the dry material through the water column in bulk and across the contaminated sediment surface. Jersak presented a slide showing this process. Once the Aquablok™ settles across the contaminated surface, and within a couple of weeks (the exact time depends on the type of Aquablok™, the application method, and application rate), the Aquablok™ transforms from a layer of discrete particles to a unified, cohesive, and homogeneous mass that effectively sits on top of the sediments and below the water column.

Jersak then discussed how Aquablok™ meets the three capping functions. The material isolates contaminants from the benthic (invertebrate) community by providing a clean replacement substrate. Jersak showed typical burrowing depths of several species, which ranged from 0.5 to 3 inches with some worm taxa (oligochaetes) burrowing to 6 inches. The caps are typically less than 1 foot thick, which, in general, should encompass the burrowing depths of most species. However, because many factors control the bioturbation depths (including dissolved oxygen levels and substrate distribution), the benthic community should be evaluated on a site-by-site basis to characterize bioturbation depths. The benthic community may also be further isolated from the contaminated sediment as clean sediment is deposited over time, assuming adequate source control. In addition, because Aquablok™ is a fine-grained material, it can serve as a physically comparable substrate for invertebrate recolonization, assuming that most contaminated sediments are fine-grained. A participant asked if this hypothesis has been tested with detailed study. Jersak responded that although a detailed study has not been completed, anecdotal evidence from an Alaskan site has supported this belief. Currently, HAI is gathering data about the benthic community through other projects. Jersak speculated that a sand cap may encourage a different benthic community structure than previously present in fine-grained, contaminated sediments.

The second function is physically stabilizing the contaminated sediment, which is essentially a cap integrity issue. The premise is that if a cap remains stable during a high-flow event, such as a 100-year storm, the underlying sediment will remain in place. There are many environmental and economical reasons to keep the contaminated sediment in one place; among these are saving money if dredging is needed later and preventing risk associated with sediment dispersion. Jersak noted that HAI has completed laboratory flume studies of the relative erodibility of Aquablok™ and other capping materials (sands and gravel) and that an erosion CD-ROM is available upon request. The flume system for conducting these studies consists of an 8-foot-long, 4-inch-diameter clear tube; flow velocities and durations can be controlled using this apparatus. Tested material included sand at approximately 1.5 to 3 feet per second flow velocity and Aquablok™ at 4 to 6 feet per second. Results of laboratory tests indicate that Aquablok™, as a cohesive material, is very resistant to erosion at flow velocities up to 5 feet per second over several days. In contrast, the sandy material showed significant and rapid erosion at flow velocities of less than 3 feet per second. Gravel fell between the Aquablok™ and sand results.

The third capping function is reduction of dissolved contaminant movement through the sediments into the water column. The cap protects the benthic community in this respect by preventing contaminants from migrating upward toward the benthic community (i.e., the bioturbation zone). Other studies show that once contaminants enter the bioturbation zone, however, the contaminants are quickly released to the overlying water column. The goal of capping is to maximize the time it takes dissolved contaminants to move from the sediment/cap interface up to the base of the bioturbation zone. To address this issue, HAI studied advection (bulk flow of water as a function of gradient and permeability of the substrate) and diffusion (concentration gradient driven transport of dissolved contaminants). Superimposed over these two processes is chemical attenuation of dissolved contaminants by solid-phase surfaces within the sediment or cap. Small- and large-scale laboratory studies found Aquablok™ permeability to be between 10-8 and 10-9 centimeters per second. This applies to the "typical" Aquablok™ compositions (approximately half clay and half gravel by weight), as well as to relatively "lean" mixes (20% clay and 80% gravel). In addition, the attenuating potential of an Aquablok™ cap can be increased by using reactive organic clays (called organoclays) to encourage increased contaminant attenuation. Given the low permeability and potential for contaminant interactions with the clays, contaminant movement through Aquablok™ caps will be limited.

Jersak presented the Fort Richardson Army Base in Alaska as an example Aquablok™ application to a wetland ecosystem. As a result of ordnance disposal over several decades, sediments at the site were contaminated with white phosphorus to the point that waterfowl deaths occurred. Animal researchers with the U. S. Department of Agriculture (USDA) tested several techniques for addressing sediment contamination, ranging from draining ponds to promote white phosphorus sublimation, to hazing (preventing birds from entering the area), to using Aquablok™ to isolate the sediments. As a result of these studies, Aquablok™ was selected as one of the remediation alternatives for the site. USDA researchers established treatment and control pens into which they placed wing-clipped mallards. They conducted mortality studies for the treated and untreated areas. The study results indicated decreased mortality in the Aquablok™ treatment pen, indicating that Aquablok™ can isolate sediments below depths to which waterfowl can dabble. Results also indicated that, at this site, Aquablok™ can act as a viable substrate for vegetation regrowth and for at least one species of macroinvertebrate. Jersak showed two photographs taken before and after the Aquablok™ was applied to illustrate that the material can act as a viable substrate for vegetation regrowth. After 1 year, lush vegetation and a macroinvertebrate species were supported by the cap. There were no noticeable impacts on the surface water hydrology.

A participant asked if other innovative technologies were tested at this site. Jersak indicated that another, pulp-based capping material was tested and that waterfowl were observed to easily break or dabble through this material. As a noted, conventional dredging was not seen as a viable option for sediment remediation at this site due to the potential presence of unexploded ordinance. Furthermore, in terms of how Aquablok™ will be incorporated into sediment remediation at the site, it will likely be used in ponded areas that cannot be easily drained; where possible, areas that can be drained will be drained to promote sublimation of the white phosphorus (encourage reactions with the atmosphere).

An audience member asked if Aquablok™ application to an uneven surface, perhaps areas with tree stumps or debris, had been tested. Jersak responded that this has not yet been tested. Field transect investigations at the Toledo, Ohio (Ottawa River) site, where a field demonstration of Aquablok™ application will soon occur, indicates relatively low relief with few stumps or debris, so this should not be an issue at this site. At other sites, in areas of extreme relief or where things like tires and tree stumps occur, there may be not be complete coverage of such items, but the sediment mass will be covered, which is the most important consideration.

A participant then asked how effective coverage is measured, by cover thickness or by other parameters such as water column levels or appearance of contaminants in biota. Jersak answered that there are generally two monitoring approaches used during installation verification and long-term monitoring. The indirect approach includes determining the pre- and post-cap bed elevations, with the difference indicating cap presence and thickness. This is one of the primary monitoring methods used during capping, according to the ARCS document. Sonar techniques can also be used as an indirect approach to determine cap presence or absence. In contrast, direct approaches to monitoring include core sample collection for visual cap inspection, and to verify that bed-elevation increases, for example, are due to cap presence rather than sediment accumulation. The direct monitoring approach adds details that the indirect methods do not provide.

To place Aquablok™ in the context of an overall in situ capping project, Jersak presented some chronological issues to consider. The overall project goal dictates the remedial actions—for example, is the project goal to physically contain the sediment in one place or to reduce body burden of contaminants in organisms? Based on goals and site conditions, a cap can be designed to meet project goals. Next, one must identify the appropriate equipment to install the cap, which depends on site-specific conditions such as site accessibility. Options range from shore-based conveyors to barge systems. At the Alaska site, helicopters were used to apply the cap material, primarily because of the danger from unexploded ordnance. The next step is to develop a monitoring program to verify that the cap was correctly installed, remains stable, and maintains function over time; Jersak stated that the monitoring should be considered an integral part of any capping project. Then one must estimate costs. Remediation through capping can theoretically be rejected as an option at any point in this chronological process. Site conditions to consider in designing a cap include water depth, flow rates, erosion events (flooding), source control, and sediment contaminant distribution. There should also be an understanding of the physical characteristics of the sediments involved, such as moisture content and particle size.

Jersak concluded the presentation by summarizing his key points. Aquablok™ can act as a physical barrier between contaminated sediments and the overlying ecosystem, as well as a hydraulic and chemical barrier. His company believes that in situ capping is a cost-effective technology that could be used as a replacement for or in conjunction with other technologies, such as dredging. Although it is certainly not the solution to all sediment contamination issues, capping should be considered a viable option in conducting sediment remediation projects. As a final note, Jersak stated that Aquablok™ has been discussed today mainly as a sediment-capping material, but it may also have application as a barrier to protect ground-water resources or as a component of landfill liners, based on its low permeability and reactive nature.

After Jersak's presentation, one participant asked, "What is the Aquablok™ particle size once hydrated?" Jersak responded that Hull & Associates has not tracked individual particle size upon hydration, having instead focused on volume change and net cap thickness increase upon hydration. The particle size of the dry Aquablok™ material depends on its manufacturer; based on the beginning gravel size, the final product contains particles from 0.25 to over 1 inch in diameter. Different proportions of gravel and clay will alter the percentage of different particle sizes once the product is prepared.

Another participant asked if particles of Aquablok™ material remain discrete or merge after hydration. Jersak answered that the expanding bentonite fills the secondary pore spaces as the particles hydrate to form a coalesced layer. The final consistency is a thick, gooey substance, similar to wetland sediments. The final cap is cohesive and resistant to flow, but not strong (competent) enough to stand on.

A participant asked about the organic carbon component, and questioned why an organism would inhabit a "cohesive, gooey substance," as Jersak described the Aquablok™. To the first question, Jersak answered that the organic carbon content of the clay component in a typical formulation is approximately 0.5%. In answering the second concern, Jersak stated that there is a physical similarity between the Aquablok™ and fine-grained sediments. Dissolved oxygen and organic carbon concentration differences may occur between Aquablok™ and sediments, as least initially. Potential effects of this on the benthic community will be tested. Jersak also stated that, over time, secondary coverage of caps with clean sediments may also help provide an inhabitable environment.

One participant expressed concern that animals would ingest unhydrated material immediately after application, and asked if this has been considered. This participant also questioned if the mallards at the Alaska site did not penetrate the Aquablok™ layer because of physical restrictions or because of other factors. Answering the first question, Jersak said that HAI is considering studies of Aquablok™ compatibility with invertebrate organisms/communities. To the second question, Jersak responded that, at the Alaska site, the mortality rate studies conducted by the USDA in 1994 were completed soon after the cap was installed and indicated that the cap presented a physical barrier. As part of the study, USDA observed dabbling and feeding behavior, and noted that the mallards were dabbling in the capped areas and, therefore, potentially disturbing the material. In 1995, USDA returned and conducted additional investigations and also observed dabbling and foraging behavior. Jersak speculated that if the material was not serving as a chemical barrier to some degree (in addition to a physical barrier), some mortality might have been seen in the 1995 study.

One participant asked about the cost of using Aquablok™. Hull responded that the Alaska project cost $55,000 to $60,000 per acre to install a 4- to 6-inch Aquablok™ layer. However, a fairly expensive application method (helicopters) was used. Depending on the particular application, Hull is hoping the cost will be less than $1 per square foot. Combining Aquablok™ with other materials, such as a sand layer, could further reduce costs.

In a wetland environment with a peat base that is covered with clay, an anaerobic environment is created. One participant, having brought this up, asked about gas migration and potential cap impacts from this gas. Jersak said that this issue is similar to those that arise when capping an area with upwelling ground water. These site-specific issues need to be addressed, especially for a ground-water concerns but also for gas concerns. Literature for sites with geomembranes is available, and include studies of piping and venting systems. Jersak noted that installing piping and venting may not be feasible at all sites. He also agreed that an anaerobic environment would be created; however, many wetlands already function under anaerobic conditions anyway so such changes may be minimal. HAI is currently considering ground-water and gas migration concerns with some small-scale studies and computer modeling. Results may be applied to a large-scale laboratory study before the technology is implemented in the field.

One participant asked about hydrating Aquablok™ before application, particularly if applying it in a situation in which it is exposed to the elements before being placed in its final location. For example, in areas with difficult access, one option may be to place the material on ice and then let the cap settle when the ice melts. Jersak noted that bentonite-based landfill liner materials, pose the same handling challenges as Aquablok™. Because of its consistency after hydration, Aquablok™ could not be stockpiled on site without a cover. Placing the Aquablok™ on ice was considered at the Alaska site, but there were too many uncertainties about ice and flow movement to ensure adequate capping. Hull stated that the particles could be coated with an organic polymer to slow hydration, if needed.

Because some sediments have very low density, one participant asked if HAI has studied application of Aquablok™ to lower density sediments. The issue of density and distribution, Jersak responded, was one of the first concerns addressed in studying this material and dictated much of the initial laboratory research conducted for the Ottawa River demonstration site. Jersak stated that beyond the compatibility issues, if Aquablok™ or any other capping material cannot be applied and remain in place atop the sediments, it is essentially ineffective. Dry weight densities of Aquablok™ particles range from 1.6 to 2.3 grams per cubic centimeter, which is lower than typical sand or gravel densities. In large-scale column studies, Aquablok™ did not significantly "sink" into and become incorporated with the contaminated sediment mass being capped. There was some degree of mixing at the sediment/cap interface, but this was not significant. In applying the capping material, there must be an understanding of the application rate (amount) needed to form a cohesive unit of the proper thickness. This is a site-specific concern.

If the material is not "attached" to the substrate being capped, one participant asked, could the cap withstand the flow velocities seen in the laboratory studies? Jersak responded that cap stability is one parameter being studied at the Toledo, Ohio (Ottawa River), demonstration site. One concern of the participants is that at high flow rates, the edge of the cap could be lifted and pulled away. To address this concern, incorporating design methods for stabilizing the upstream edge of a remedial sediment cap could be explored. Jersak reiterated that the Aquablok™ does, to some degree, mix with the sediment being capped to create an "attachment" to the sediment to keep the cap in place.

A participant asked what measures are needed to gain regulatory acceptance of this capping technology and to begin commercial production. Hull said that regulatory agency acceptance varies across the country. Another participant noted that the Office of Research and Development (ORD) is studying this technology; if ORD accepts this technology, the participant said, then it will likely be accepted by other agencies. Hull indicated Aquablok™ is typically produced on site and the technology exists for mass production. For the Alaska site, material was manufactured in 2 days and applied over a 1-acre area in 2 days. Hull expects that this time frame can be shortened.

As a final question, a participant asked about the leaching potential of the organic polymers used to bind the clay to the gravel. Hull indicated that the polymers used are bio-friendly and have relatively low organic content levels. The organic polymers are only needed for material placement, so later leaching would not affect cap performance.

Jensen asked if the Sediments Remediation Action Team could visit the Ottawa River demonstration project. Jersak and Hull provided some background information regarding this demonstration project. The demonstration project consists of capping a 3-acre area in the upper reaches of the Ottawa River near Toledo, Ohio. In the area under study, PCBs, PAHs, and heavy metals contribute to the down-stream sediment contamination problems in the river. Eventually, these sediments migrate in river water that discharges to the Lake Erie. Many of the sources (landfills and dump sites) have been addressed and are no longer contributing contamination to the river. The Ottawa River demonstration project involves capping with three different cap designs. Field conditions were characterized and settling-column pilot studies were conducted in the laboratory using river sediments. HAI also completed hydrologic and hydraulic modeling studies to predict potential impacts of the capping, which appear to be insignificant. The final cap thickness will be approximately 5 to 6 inches where protective stone is not present, and 7 to 8 inches where a surficial stone layer is present. Baseline (pre-capping) characterization of benthic (invertebrate) communities in the capping area is scheduled to begin on or near June 15, 1999, and will last 6 weeks. Therefore, cap application should occur during the first or second week of August 1999. Hull will speak with the project engineers and the Sediments Remediation Action Team to schedule a site visit.

POTENTIAL CAPPING PILOT UPDATE
John Smith, Alcoa, Inc.

As a follow-up to the last RTDF meeting, John Smith presented a site update for Alcoa's Grasse River capping project. At the last meeting, Smith provided site background, and at this meeting Davis discussed the proposed pilot demonstration. Alcoa, Inc., is currently negotiating the project scope with EPA, the New York Department of Environmental Conservation (NYDEC), and the St. Regis Mohawk Tribe. In 1998, Alcoa, Inc., proposed to conduct a 1-mile pilot demonstration of particle broadcasting. However, EPA has since indicated that they are uncomfortable with the 1-mile study area. Therefore, the parties involved are discussing the completion of a smaller-scale demonstration in summer 1999.

Smith noted that this project evaluates particle broadcasting (a form of enhanced natural attenuation) as an alternative technology. These technologies are different from capping, but do include applying a thin cap layer. This cap is only thick enough to maintain its stability and raise the bioturbation zone above the contaminated area. The cap also acts as a barrier to prevent vertical contaminant migration and prevent ground-water flux. Initial studies have estimated PCB breakthrough approximately 200 years after installation. Therefore, particle broadcasting is considered a permanent remedy.

Smith indicated that the Grasse River was selected as a demonstration site because it has the right characteristics to support this technology. The river was dredged in the early 1900s, becoming a backwater to the St. Lawrence. The Grasse River is 20 to 30 feet deep and has a 6-inch to 3-foot sediment layer. Contaminated sediments are located along a 4- to 5-mile stretch of the river. One of the concerns about the site is the presence of a hard pan layer underlying the contaminated sediments. The maximum flow rates are very low: the average flow rate is only 0.02 to 0.03 feet per second and the January thaw flow rates are 2 to 3 feet per second. Investigations have found very little ground-water flux.

Smith next discussed some of the critical engineering issues addressed while designing this project. The first issue was cap configuration and deployment. Alcoa, Inc., is examining several materials, although they have not considered Aquablok™. Materials under consideration include one composed of fine- to medium-grain sand with an organic carbon content of 2% to 5% from a local source. Alcoa, Inc., determined that the dry application is the best method for obtaining uniform placement. Other concerns were cap placement and migration, particle sorting, particle consolidation over time, resuspension of bottom sediments, contamination of capping material, cap integrity, and physical and biological erosion.

To address these concerns, Alcoa, Inc., is conducting pre-design studies and implementation tests before commencing the pilot demonstration. Numerous geophysical surveys found the hard pan layer, mentioned earlier, underlying river sediments. Higher contamination concentrations are found at the hard pan layer, and this is a consideration in evaluating dredging as a remedial option. Current laboratory studies include settling column tests, cap stability studies, and PCB migration studies. The settling column tests have focused not only on the cap material's physical properties, but also on different application techniques. The settling tests examine how the material settles through the column. Once the material has settled, these tests examine how it consolidates and if there is uniformity in particle size throughout the cap. These tests also examine PCB movement caused by disturbing the contaminated sediment during cap application.

Stability studies include flume studies to ensure that the maximum velocities observed in the Grasse River would scour the cap. (One participant asked how Alcoa, Inc., collected the Grasse River sediments to recreate natural conditions in the laboratory column tests. Smith responded that Alcoa, Inc., collected unconsolidated sediments from the surface in areas with known high PCB concentrations. Overall, Alcoa, Inc., tried to collect sediments that are somewhat representative of the river.) The study was designed to represent a worst-case scenario. Sediments were allowed to consolidate for only 2 weeks before studies began although greater consolidation would be observed in the river. Alcoa, Inc., was interested in the physical movement of sediments during cap application. Smith commented that Alcoa, Inc., is also conducting modeling studies to examine sediment movement, including two-dimensional hydrodynamic modeling and sediment transport modeling. These modeling studies are also examining the impact of high-flow events on cap stability. The study uses the sediment transport model to simulate the cap over a portion of the river and during a series of rare flow events (100- to 500-year storm events). This modeling uses information developed during the flume studies. The purpose of these studies is to optimize the cap design.

Alcoa, Inc., is also conducting PCB migration tests to study diffusive flux. These tests are being completed in the laboratory; they involve a series of microcosms capped with different materials at different thicknesses (0.5 to 1.0 inches). Smith noted that in the demonstration study, the final cap thickness should be 4 to 6 inches. One participant asked if the PCB migration tests include methods to examine processes occurring under the cap, such as biodegradation. Smith responded that Alcoa, Inc., is conducting ongoing biodegradation studies with microcosms. Some of these studies have been ongoing for 2 years and have detected some dechlorination. Sediment cores have also been collected from the Grasse River and significant dechlorination has been observed. However, biodegradation is not being used to support the remedial action. Alcoa, Inc., realizes that if particle broadcasting is selected as the remedial option, long-term monitoring would be required and would likely include tracking PCB contamination under the cap.

Other investigations are examining the fate of PCBs to evaluate the long-term effectiveness of caps. Migration studies are in place, and have estimated a 200-year breakthrough time for dichlorobiphenyls. Considering the slow migration time, Smith believes that biodegradation will occur in the bioturbation zone. In pore water studies, Alcoa, Inc., has observed high monochlorobiphenyl concentrations, but these concentrations have not been detected in the water column. Therefore, Alcoa, Inc., hypothesized that monochlorobiphenyls are readily biodegrading in the aerobic zone of the sediment. Smith noted that breakthrough is inevitable, but the cap will reduce the amount of PCBs entering the water column to 0.5% to 1.0% of the current flux. At the slow flux rate, there are greater opportunities for biodegradation. Smith said that Alcoa, Inc., is conducting extensive dechlorination and degradation studies.

Field studies at the Grasse River have included or will include geophysical surveys to establish current river bed conditions. Bathymetry and sonar studies have been conducted to provide a physical characterization of the river. One participant asked how the substrate characterization was completed. Smith responded that sonar scanning from boats on the river was used. The sonar penetrated several layers of sediment to differentiate the sediments from the surface to the till layer at approximately 3 feet. River bed elevation monitoring will allow Alcoa, Inc., to evaluate particle coverage after application and after the first spring thaw. River bed elevations, at 12 to 13 locations, were measured with a series of aluminum plates placed on the sediment surface. These plates were surveyed using global positioning systems (GPS) and can be easily relocated using GPS. To measure elevation changes after the particle broadcasting, a surveying rod with a small plate on the end is placed on top of the aluminum plate and capping material and surveyed. More plates will be installed during the pilot demonstration to establish sediment bed elevation, cap thickness, and periodic sampling to evaluate erosion or deposition.

Smith noted that groundwater seepage is a concern when using a capping technology. Alcoa, Inc., installed multiple monitoring wells and seepage meters along the Grasse River to evaluate ground-water flux, which can significantly impact a cap's effectiveness. Current data indicate that there is little to no ground-water flux compared to the diffusive flux. One participant asked if there is a means for ongoing monitoring. Smith responded that seepage meters with continuous monitoring, as well as ground-water monitoring wells, will continue to be used. The pilot demonstration should provide valuable information about ground-water flux. Another participant asked if the colloidal content of the ground water has been investigated. Smith stated that Alcoa, Inc., completed water column studies looking for colloids, but did not find any. These studies have also looked for algae and radioisotopes. During investigations, however, Alcoa, Inc., observed St. Lawrence river water was flowing under the Grasse River water, as indicated by temperature differences. Underflow velocity data have not been collected, but the presence of the thermocline is evidence that the velocity is very low.

The current proposal for a demonstration test includes a 150-foot-square test cell on the north side of the river. The test would include adding capping material and monitoring. Coring would be conducted to examine PCB migration through the cap. The proposal would include installing the cap in summer 1999 and conducting monitoring and evaluating in spring 2000. Smith noted that the test cell study is part of a work plan that is still under development and has not yet been approved by the regulatory authorities. The pilot study size was reduced due to EPA's concerns.

Smith opened the discussion to participant questions.

One participant asked about cap permeability at the Grasse River site. Smith noted that permeability has not been tested. Because ground-water flux is low, the modeling and studies have focused on PCB migration through diffusive flux. The proposed cap is composed of fine- to medium-grained sand.

Another participant asked if there is an opportunity for RTDF involvement. Smith stated that there may be some possibility for RTDF involvement. However, the regulatory agencies must first approve the project. There may be an opportunity for a site visit once the regulatory approvals have been received.

A participant noted that significant time, effort, and funding have been dedicated to the particle broadcasting alternative. He questioned if it would have been better to have just dredged the river. Smith noted that the final remedial action is still under consideration. The studies have not truly caused project delays because source remediation is ongoing: several outfalls are still contributing PCBs to the river during storm and high-flow events. The regulatory agencies have agreed that sediment remediation should not occur until the sources are controlled. Alcoa, Inc., has been conducting these sediment studies to provide an overall understanding of PCB behavior and migration and river conditions. Dredging has been discussed, but the entire 4 to 5 miles of contaminated sediment is contributing PCBs into the water column through diffusive flux. No true hot spots have been identified. Therefore, a surface wide solution is needed, which would require dredging along the entire length of contaminated sediment. In addition, the hard pan would render dredging difficult. Although the ultimate solution has not been selected, Smith indicated that he is confident that some kind of capping would provide the fastest recovery. Some natural recovery has been observed: clean sediments are being deposited at a rate of approximately 0.5 centimeters per year. This is slower, however, than is needed to address the PCB contamination. Therefore, the cap is intended to enhance natural recovery. Smith has used the definition of natural recovery that is given in EPA's sediment guidance manual.

PHYTOREMEDIATION OPPORTUNITY AND FIELD VISIT TO BROOKHAVEN
Richard Jensen, DuPont Corporate Remediation
slides prepared by Michael Coia, Phytoworks, Inc.

Because Michael Coia was unable to attend the meeting, Jensen presented Coia's material. The overheads used in this presentation are provided in Attachment H. Coia's presentation provided an overview for several potential RTDF phytoremediation demonstration project sites. The potential demonstrations sites include:

• Brookhaven National Laboratory, New York. The Peconic River sediments and wastewater treatment plant filter beds have been identified as potential demonstration sites. These sites are contaminated with radionuclides, PCBs, and mercury. The Peconic River sediments would undergo wetland phytoremediation, while terrestrial phytoremediation would apply to the wastewater treatment plant filter beds. The Sediments Remediation Action Team would focus on the Peconic River sediments remediation.
• Cache Creek Watershed, California. This site may serve as an alternative to Brookhaven National Laboratory. Sediments at this site are contaminated with mercury.
• Sulfur Bank Superfund Site, California. This site could also serve as an alternative to the Brookhaven National Laboratory sites. Sediments at this site are also contaminated with mercury.

Jensen noted that Phytoworks, Inc., has conducted multiple projects addressing mercury in sediments. Phytoworks, Inc., is a company that genetically engineers plants to transform mercury from one species to another. One of Phytowork's engineered plant species transforms mercury to its elemental form, which is then transpired from the leaves into the atmosphere. There has been some concern about allowing mercury to transpire. However, Jensen said the rate of mercury transpiring is very low. Also, the plants can be engineered so that the mercury can be accumulated in the leaves rather than transpired. Jensen noted that only a few people are experimenting with genetically engineering plants to transform contaminants.

At the Brookhaven National Laboratory, the Peconic River sediments were contaminated by effluent discharging from the wastewater treatment plant. Contaminants are concentrated in shallow sediments in wetland areas and include cesium, PCBs, and mercury. Six wastewater treatment plant filter beds are located at Brookhaven National Laboratory. The filter beds serve as an ongoing source of cesium and mercury to the sediments. As currently planned, the sediments and filter beds will be remediated concurrently.

Investigations and research at Brookhaven National Laboratory are ongoing. There is an ongoing phytoremediation study using terrestrial plants to remediate cesium contamination. This study has shown some promising results. The study is being completed as part of a joint effort with USDA and Cornell University and a CRADA research project has recently been initiated. This is a DOE-funded project that includes laboratory study of terrestrial and wetland phytoremediation. The project studies mercury uptake in transgenic plants and cesium uptake in native plants. However, the funding applies only to the laboratory treatability study; there is no funding for field studies. A field application demonstration would require follow-up funding at sites designated by Brookhaven National Laboratory.

Jensen said that Coia has proposed a team alliance with the Sediments Remediation Action Team for conducting the field applications demonstration. The project would be linked to the existing Brookhaven National Laboratory information. According to Jensen, Coia estimated that the demonstration project would include two test plots in the Peconic River and one test plot in the wastewater treatment plant filter beds. The test plots would be approximately 20 feet by 50 feet and include a mixture of native and transgenic species. The demonstration would include soil removals to estimate plant uptake rates. This is anticipated to be a 12- to 18-month study since it must cover multiple growth cycles.

In estimating funding for the field application demonstration, Coia designated non-funded "in-kind" services (which would be provided on a voluntary basis) and funded efforts. The non-funded services include the following:

• ART completes the study design, work plan, and engineering during the ongoing CRADA laboratory tests (spring and summer 1999).
• Brookhaven National Laboratory, USDA, and Cornell complete the initial laboratory CRADA.
• RTDF assists during the planning and field operations.

The funded efforts include:

• Dr. Carreira completes the PCB-degradation enzyme analysis.
• Dr. Meagher completes a study of mercury transformation in transgenic wetland species.
• Enviroscapes, Inc., constructs and operates the field test plots.

The proposed funding summary included approximately $190,000 in "in-kind" or volunteer services for the non-funded portion of the project. Approximately $210,000 would be required for the funded portions of the demonstration. Jensen noted that the proposed funding is within RTDF limits.

Before RTDF commits to funding this project, one participant commented, technical documents and supporting information for this approach should be reviewed. Jensen agreed that the Sediments Remediation Action Team should further discuss approaches and technical documentation before committing funding to this project. However, Jensen believes that the science is good and that at this point, it would be beneficial for the Sediments Remediation Action Team to explore options for this matter further.

As a potential path forward, Jensen believes that the groups need to meet at Brookhaven National Laboratory to raise questions, obtain technical documentation, and conduct a site visit. The project would require RTDF members with different skills and experiences to help evaluate the project. Members of the Phytoremediation of Organics Action Team could be included. After gaining confidence and understanding of the project, RTDF could explore funding opportunities. Jensen stated that he would like to conduct these meetings and the site visit during the summer of 1999. One participant requested that further information, such as technical papers, be distributed before the site visit. This would identify members who may be interested in the project and also identify what technical experiences may be necessary. Jensen agreed and stated that he would pursue this with Coia. This information may be most easily posted on the Web site (www.rtdf.org).

UPDATE ON THE SEDIMENTS MANAGEMENT WORK GROUP'S ACTIVITIES
John George, Alcoa, Inc.

John George briefly provided background information about the SMWG. Overheads used during George's presentation are provided in Attachment I. The group was formed in May 1998 to establish a coordinated approach to evaluating contaminated sediment sites by parties responsible for implementing sediment management strategies. Currently, there are approximately 30 entities in the group.

George listed several reasons for forming the group:

• Sediment management decisions are at a critical crossroads.
• There is a need for an objective scientific foundation to ensure sound decision-making.
• Review of existing data suggests that there are key gaps in the knowledge base.
• The group believes that a coordinated perspective is the key to success.

George stated that an effective strategy for managing contaminated sediments must be founded in good science and allow access to appropriate tools for site characterization, risk assessment, risk management, understanding remediation techniques and limitations, and ongoing monitoring. The group's mission is to advance risk-based, scientifically sound approaches for evaluation of sediment management decisions. Based on this mission, they have established this objective: to collect, develop, analyze, and share data and information on the effectiveness of sediment management technologies and approaches.

George presented some of the SMWG's near-term work products. George noted that the products listed were in process when the group was initiated in May 1998. In February 1999, the Manistique Harbor Remediation Monitoring Report was published. In addition, a comprehensive database of contaminated sediments sites is in the final stages of development and validation. This should be available in June 1999. Group members are also working with Alcoa, Inc., to examine the effectiveness of dredging at a variety of different sites. A technical paper with results should be available in draft form in summer 1999.

With respect to formulating an approach to their objective, George stated that shortly after its founding, the group identified the key technical issues for any contaminated sediment management strategy. These key issues include: conceptual site models, natural recovery evaluations, risk management principles, natural processes impacts, sediment stability, and applicability/capabilities of active remediation technologies (removal, containment, and enhanced natural attenuation). To address these key issues, the SMWG developed a series of technical papers directed to the technical community. The technical papers were developed by recognized experts; they are intended to provide a tool for developing consistent and effective sediment management strategies, and to stimulate further discussion. The technical papers should eventually be available at the SMWG Web site (www.smwg.org). Eventually the technical papers may be republished in a format suitable for the general population. One participant questioned if the technical papers have been peer-reviewed. George stated that the papers underwent a peer-review process for the SMWG, but have not undergone a peer-review process for publication in technical journals. However, the SMWG encourages the authors to undergo this process.

The SMWG is also working to produce a decision tree tool. They intend to create a decision tree that is interactive, but integrates the technical issues. An investigator may be able to enter the decision tree with a hypothetical site. This tool would help an investigator reach some conclusions about data limitations and data gaps during the site characterization phase, resolve outstanding data limitation and data gap issues, and perform the risk assessment. The decision tree will include several feedback loops to determine if data are adequate for decision-making and if the site is fully characterized. The final step of the decision tree will allow for evaluation of potential remedial alternatives, using natural recovery as the baseline. Off shoots of the decision tree will examine whether or not there are active and ongoing sources that must be addressed. George stated the SMWG is hoping to post the decision tree on their Web site, and include links to the supporting technical papers and sites with additional information.

George said that one question for the SMWG was how they relate to the RTDF Sediments Remediation Action Team. George believes these groups have a strong alignment of goals and objectives. Both groups view objective science as the basis for making informed decisions about contaminated sediments management and both groups aim to develop tools to help individuals assessing contaminated sediments remediation strategies, as viewed from a regulatory perspective. Therefore, George stated, there are many opportunities for these two groups to support each other and share information.

To close, George presented the SMWG's near-term schedule. This schedule includes a series of presentations and meetings. The SMWG has the opportunity to present to the NAS to provide information about the group and its work products. In addition, the schedule includes holding a session about contaminated sediments at the upcoming Society of Environmental Toxicology and Chemistry (SETAC) meeting (November 17 to 19, 1999). This session will be founded on the technical papers. In addition, the group is continuing to develop technical papers. More information about the group may be found at their Web site. Currently, the site has a membership list and a list of activities, and there are plans to post the technical papers.

SITE UPDATES FROM MEETING PARTICIPANTS
facilitated by Richard Jensen, DuPont Corporate Remediation

Jensen opened the meeting to members to add comments about ongoing projects. Greg Planicka, from the National Environmental Policy Institute (NEPI), briefly described his organization's function and stated that his company is contemplating forming a sediments work group. Planicka stated that NEPI's role has been primarily to act as facilitator and convener for different organizations and individuals for multiple topics, but its projects have been primarily science based. One example is the current bioavailability policy project which started in September 1996 when the question of "how clean is clean" was raised. This is an ongoing project exploring issues related to metals and organics contamination. NEPI became involved with bioavailability issues because of the impact of technical issues on policy and decision-making. One concern noted by Planicka was that perhaps the wrong questions were being asked to determine what acceptable cleanup standards are. NEPI also noted that many of the remedial project managers at contaminated site had the technical authority to make remedial action decisions and relied heavily on the toxicology and risk assessment information. However, these managers often did not have sufficient information about a site to ask the appropriate questions about collecting information and how to include information in a site assessment to support risk assessments. Therefore, NEPI has tried to address these issues in technical papers. These papers address regulatory policies and assess the current scientific knowledge to encourage technologies that work or are worth pursuing. Planicka noted that NEPI's true value is in bringing people together, including the state and local regulators, to bring common sense and a strong science base to decision-making. NEPI communicates their message by convening working groups with multi-disciplinary experiences and producing white papers. In addition, each group is structured around an aggressive communication and education program, which may include symposiums, conferences, and congressional round tables. By bringing this information to attention, NEPI hopes to create a greater dialogue between parties. Planicka believes that sediments contamination issues are currently an important topic.

CLOSING COMMENTS

Jensen closed the meeting by thanking members for their attendance and participation. Hopefully, the group can conduct more conference calls, meetings, and field trips to further the team's mission and goals. Jensen noted the need for writing assignments associated with different groups and projects to move the Sediments Remediation Action Team forward. One participant requested a distribution list for team members. Jensen noted that a complete member list is available on the web site. The team tentatively agreed to meet again during the SETAC meeting in November 1999.

Attachment A
Final Attendee List

RTDF Sediments Remediation
Action Team Meeting

Regal Riverfront Hotel
St. Louis, Missouri
May 25, 1999

Final Attendee List

Attachments B-I

Attachment B: Welcome, Opening Remarks, and Description of Meeting Objectives (Richard Jensen)

Attachment C: Linkages With The RTDF Bioremediation Consortium (John Davis)

Attachment D: Tool For Sediment Assessment Training (Ralph Stahl)

Attachment F: Announcement: Sediments Research Web Site (Mark Hodges)

Attachment G: Aquablok™ Technology And The Possibility of a Field Visit (Joseph M. Jersak and John Hull)

Attachment H: Phytoremediation Opportunity And Field Visit to Brookhaven (Richard Jensen for Michael Coia)

Attachment I: Update on the Sediments Management Work Group's Activities (John George)