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

11:00 p.m.-12:30 p.m.
May 3, 2002

On May 3, 2002, 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)
Tim Dekker, Limno-Tech, Inc.
Joe DePinto, Limno-Tech, Inc.
Diane Douglas, DC Water Quality Division
Mike Erickson, Blasland, Bouck, and Lee, Inc.
Erin Mack, DuPont Corporate Remediation
Victor Magar, Battelle Memorial Institute
Dale Matey, U.S. Environmental Protection Agency (EPA)
Douglas McLaughlin, Blasland, Bouck, and Lee, Inc.
Clay Patmont, Anchor Environmental
Mike Swindoll, ExxonMobil Biomedical Sciences, Inc.
Brett Thomas, Chevron Texaco

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

INTRODUCTION

The Natural Recovery Subgroup is evaluating sites where monitored natural recovery (MNR) has been an integral component of remediation management strategies. The Subgroup's goal is to develop an analytical framework that can be used to assess the efficacy of MNR. Its purpose is to help evaluators hone in on data that provide important information on MNR efficacy. This is necessary because "boxloads" of data are available for some sites.

The analytical framework will be structured around five lines of evidence (LOEs). These LOEs were most recently revised at the Natural Recovery Subgroup's meeting on April 9, 2002. Within the month, John Davis and Mike Swindoll will write a short document that summarizes the five LOEs and describes the Subgroup's analytical framework. Subgroup members are expected to apply the framework to individual sites; the ultimate goal is to generate a series of MNR evaluation case studies. Clay Patmont said that it would be ideal if Subgroup members started applying the framework to individual sites before the next Subgroup meeting.

LOE DISCUSSION

Call participants discussed and commented on four of the five LOEs. Their discussion was facilitated by interactive tools (set up by Doug McLaughlin) that allowed call participants to view an Internet slide presentation while speaking with one another on the phone.

LOE #1: Characterization of Historical Contaminant Sources and Controls

Davis presented the slides for this LOE, and noted that this particular LOE generated a significant amount of discussion at the April 9, 2002, meeting. Much of the discussion focused on terminology. Davis said that he plans to differentiate between external and internal sources when writing a description of this LOE, and to define these terms as follows:

• External source: Contaminant sources to the water column in areas outside the remediation zone.



• Internal contamination: Contaminant sources in areas of the water column where remedial activities are being considered.

Davis asked for feedback on these terms. Victor Magar suggested using "primary" and "secondary" rather than "external" and "internal," where primary sources would be considered those that represent areas where contamination originates (e.g., industry outfall pipe) and secondary sources would include contaminated areas that originate from redistribution processes. Magar's suggestion was discussed, but the decision was made to use the "external"/"internal" terminology. Davis said that he will be explicit when defining the terms. Dale Matey agreed to review EPA documents to determine whether the agency has already made headway defining source terms. If so, the Subgroup may consider adopting EPA's terminology.

LOE #2: Characterization of Fate and Transport Processes

Tim Dekker said that this LOE focuses on fate and transport processes that affect the ongoing behavior of systems. He presented slides that describe the properties (e.g., diffusion, advective dispersion) that can be used to evaluate fate and transport. The LOE's presentation does not discuss extreme events (e.g., storms) and more routine disruptive events (e.g., tidal forces), Dekker noted; it might be wise, he said, to fold in such a discussion. One of Dekker's slides was a schematic drawing: an overview of the processes that impact the fate and transport of contaminants and sediment. Call participants thought the schematic was useful, but suggested attaching a note explaining that not all of the processes will be significant at each site. In a different slide, Dekker outlined the concept of a tiered evaluation approach. Call participants liked the idea of using such an approach, but thought that the concept required additional explanation. Matey said that EPA's Remedial Project Managers might not be familiar with the Tier I/Tier II terminology and approach.

LOE #3: Compilation of a Sufficient Historical Record for Chemicals of Interest To Evaluate Temporal Trends

Magar described this LOE, noting that its objective is to obtain a strong horizontal and vertical spatial overview of a site's contaminant profile. McLaughlin said that this LOE overlaps with LOE #2. Magar and Davis agreed, and said that care must be taken to establish clear linkages between the different LOEs and to indicate where overlaps exist. Magar provided a brief overview of some of the topics included under this LOE. These included: (1) the use of trend analysis, (2) the importance of quality assurance/quality control, (3) the use of statistical analysis to determine the comparability of data, and (4) the use of vertical coring analysis to augment historical data. Call participants advised adding: (1) information on the importance of using historical data to determine the likelihood of disruptive events and the way these events will impact sediment stability, and (2) an appendix that describes what is needed to compile a solid trend analysis.

LOE #4: Compilation of Historical Trends in Biological Endpoint Data To Corroborate Chemical Data

This LOE was not discussed during the conference call.

LOE #5: Development of an Acceptable and Defensible Predictive Tool (or Tools) To Allow Prediction of Future MNR

Mike Erickson presented the slides for this LOE. He asked call participants whether risk modeling should be included. Call participants debated this point, but decided that it should not be included under a description of this LOE. Defining risk-based cleanup goals is not the objective of MNR evaluation, they agreed--goals would be set prior to evaluation, and the Subgroup's objective is to determine whether MNR is helping to achieve the selected goals.

NEXT SUBGROUP MEETING

Magar suggested having the next Subgroup meeting at Battelle Memorial Institute's facilities in Columbus, Ohio. Call participants expressed enthusiasm for this suggestion.

ACTION ITEMS

• Magar will find out whether Battelle can host a 1-day meeting sometime between June 17 and 28, 2002. He will report his findings to Davis.



• Matey will review EPA documents to determine whether the agency has made headway defining source terms.



• Magar agreed to forward a slide to Dekker.



• Subgroup members agreed to send comments on the five LOEs to Davis or Swindoll as soon as possible.



• Over the next few weeks, Davis and Swindoll will summarize the five LOEs and create the Subgroup's analytical framework for MNR evaluation at sites with historical data.



• ERG will set up the next call for May 31, 2002, between 11:00 and 12:30 Eastern Daylight Time.