SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
SEDIMENTS REMEDIATION ACTION TEAM
NATURAL RECOVERY SUBGROUP CONFERENCE CALL

August 24, 2000
1:30 p.m-2:30 p.m.

On Thursday, August 24, 2000, the following members of the Remediation Technologies Development Forum's (RTDF's) Sediments Remediation Action Team, Natural Recovery Subgroup, met in a conference call:

John Davis, The Dow Chemical Company (Subgroup co-chair)
Richard Jensen, DuPont Corporate Remediation
Erin Mack, DuPont Corporate Remediation
Victor Magar, Battelle Memorial Institute

Christine Hartnett of Eastern Research Group, Inc. (ERG), was also present.

INTRODUCTION

The Natural Recovery Subgroup was formed to promote the use of monitored natural recovery (MNR) as a remedial option for contaminated sediments. The Subgroup met via conference call on August 18, 2000. During that call, Subgroup members agreed to write a short document on MNR and started drafting an outline for the text. At the end of the call, Subgroup members agreed to continue their discussions in another conference call. The proceedings from this second call are summarized below.

THE DOCUMENT'S OUTLINE

John Davis proposed calling the Subgroup's document Monitored Natural Recovery of Sediments. Subgroup members approved of this title. Davis presented a proposed outline for the document, noting that it summarized what had been agreed upon during the Subgroup's previous conference call. The outline listed the following sections:

Definition

Davis said that the document will begin with a definition of MNR; this definition will provide the groundwork for the entire document. Richard Jensen said that he has started writing text for this section, but that he has not completed it yet. For example, Jensen said, he still needs to incorporate a point that Ken Finkelstein made during the last conference call: the regulated community will be required to show that MNR achieves results as quickly as other remedial options. Davis said it might be useful to define MNR as a risk management strategy that relies on natural mechanisms to reduce or immobilize contamination.

Documenting Processes Involved in MNR

Davis said that he and Erin Mack will write about activities that must be undertaken to document the processes involved with MNR. After reading through the list of necessary activities, he said, readers should understand that MNR is not a "no action" strategy, as some people have suggested. Davis said that a variety of processes will be discussed, including transport of sediments, bioturbation, biomixing, deposition of contaminated sediments, burial, and transfer through the food web.

Call participants listed some additional issues that should be discussed in this section:

• Identifying endpoints. Call participants acknowledged that defining endpoints is a controversial policy issue. In some states, efforts are underway to create contaminant concentration standards for sediments. In some situations, call participants noted, regulators may specify a mass removal goal (e.g., 95%). The endpoints chosen will vary on a site-by-site basis. Therefore, call participants agreed, the Subgroup's document should not promote the use of a single type of endpoint. Rather, it will indicate that it is useful to use a risk-based approach when identifying endpoints. This section will also clearly state that, before initiating remedial processes, one must (1) identify appropriate endpoints and (2) indicate which portion of the sediments must meet the endpoints.



• Ongoing sources. Mack and Victor Magar stressed the importance of determining whether ongoing sources are present at a site. If they are, Magar said, it is often pointless to implement a remediation effort.



• The fate and transport of different types of contaminants. Davis noted that a contaminant's properties impact its fate. Thus, the Subgroup's document will provide brief descriptions of the processes that impact the fate of broad classes of chemicals, such as petroleum hydrocarbons, chlorinated organics, and metals. For example, Davis said, the text will indicate that polychlorinated biphenyls are known to dechlorinate.



• How the quantity of a contaminant and the area of its distribution impacts the choice of a remedial option. Davis noted that an investigator's choice of remedial actions will be influenced by the extent of contamination. For example, he said, if 1 kilogram of contaminant were isolated in a small area, MNR might not be considered an optimal cleanup strategy. If, however, the same amount of contaminant were spread over 2 square miles, MNR might be a logical approach to use.



• Permanence of results. Call participants brought up a question: Can a site ever be officially closed if MNR is used as a remedial option? To close a site, they noted, regulators must be assured that the site is stable, it poses no current or potential future risks, and contaminants are not migrating from it.

The Pros and Cons of MNR

Davis said that Finkelstein has been asked to write text on MNR's pros (e.g., minimal disturbance to the environment) and cons (e.g., leaving contaminants in place). Jensen said that the Sediment Management Work Group (SMWG) has produced a paper that addresses pros and cons from the regulated communities perspective. He said that the paper, Paul Doody's Advantages and Disadvantages of Remediation Technologies for Contaminated Sediments, might serve as a useful source of information and can be found at http://www.smwg.org. (During the call, Jensen downloaded the document and e-mailed it to Subgroup members.)

Tools

Davis said that the Subgroup's document will contain information about two categories of tools:

• Physical (or non-computer) tools. Magar agreed to write text on physical tools. Davis and Mack asked him to include information on tools that monitor the long-term performance of MNR. Magar said that he would, but warned that he might not have too many tools to discuss. Davis asked whether tools have been developed to help investigators determine whether contaminated sediments are migrating. Magar said that he and Richard Brenner presented information about proposed tools at the Sediments Remediation Action Team's May 2000 meeting and that these tools are being tested. He also said that the Navy is developing advective and flux meters. These tools have promise, he said, but there are currently few concrete data on how well they work.

Davis said that it is important that he, Mack, and Magar work together while writing the Subgroup's document. Davis and Mack will forward information about the processes that they are writing about so that Magar can indicate whether tools are available to document these processes. In some instances, Davis said, it may be necessary to state that adequate tools are not available to measure certain processes. Hopefully, he said, identifying these inadequacies will prompt researchers to develop better tools. In a way, he said, the Subgroup's document will help identify research needs. If new tools are developed, he said, it would be great if the Subgroup could test them in a pilot demonstration project.

Mack asked Magar to indicate that tools are often site specific. For example, she said, it should be noted that investigators should choose an appropriate indicator organism when performing assessment tests. Davis said that it might be useful to state that investigators should not default to the same indicator organism at each site.

• Models. Jensen said that he has already made significant headway on the section that he is writing on modeling tools. The text summarizes information that was provided at a recent symposium. Jensen said that the section will describe the current state of models, how they are used, and their limitations. He said that he will stress that models should not be used to estimate parameters that can be measured empirically. Rather, they should be used to predict the future.

SOLICITING EPA'S INVOLVEMENT

No EPA representatives are currently involved in the effort to produce the Subgroup's document. Call participants agreed that EPA's input should be solicited, noting it would be useful to involve Fran Kremer. Call participants discussed the role that Kremer would be asked to play, acknowledging that she is a busy woman with limited time. They agreed to ask her to review the Subgroup's document. If Kremer also wants to provide some text, Davis said, she would be welcomed as an author.

This discussion prompted Magar to ask for more information about the relationship between the RTDF and EPA. Specifically, he wanted to know whether documents produced by the RTDF must be endorsed by EPA and represent the Agency's views. If so, he said, it might be difficult to get this document published because there is some political controversy surrounding MNR. In response to Magar's questions, Davis and Jensen said that (1) the RTDF is not considered a spokes-vehicle for EPA, (2) the Subgroup's report is unlikely to be viewed as controversial because it will address technical issues rather than policy issues, and (3) EPA does not have to officially endorse all RTDF documents. Expanding on the latter, Davis said that it is important to let Kremer know that the Subgroup will not assume that EPA has endorsed the document just because she has reviewed it. He said that it would be great if Kremer wants to endorse the document, but said that the Subgroup will refrain from listing her as a reviewer if she is uncomfortable endorsing the document. If she does not want to be listed, he said, the Subgroup will regard Kremer's review as an informal professional critique.

ACTION ITEMS

• Subgroup members agreed to prepare a draft document before the September 2000 Sediments Remediation Action Team meeting.

• Call participants agreed to ask EPA's Fran Kremer for feedback on the Subgroup's draft paper.

• Davis and Mack agreed to talk offline about ways to collaborate on the section they are writing together. They will also stay in close communication with Magar to let him know which processes will be covered in the document.

• Jensen will continue to draft text on modeling tools and the definition of MNR.