SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION ACTION TEAM MEETING
CHLORINATED SOLVENTS SUBGROUP
CONFERENCE CALL

November 15, 2001
1:00 p.m.-2:30 p.m.

On November 15, 2001, the following members of the Remediation Technologies Development Forum's Phytoremediation Action Team, Chlorinated Solvents Subgroup, met via conference call:

Bob Tossell, CH2M Hill, Inc.
Harry Compton, U.S. Environmental Protection Agency (EPA)
Xiujin Qiu, The Dow Chemical Company
Keith Rose, EPA

Also present was Christine Hartnett of Eastern Research Group, Inc.

INTRODUCTION

The Chlorinated Solvents Subgroup is drafting documents that describe how to determine if phytoremediation should be used at a given site, and also how to evaluate the technology's performance. Two documents are being created: (1) a short protocol that contains concise step-by-step instructions, and (2) a longer document that provides more detailed background information about the processes underlying chlorinated solvent degradation.

Bob Tossell said that drafts have been created for both the short and long protocol. He asked Subgroup members to focus their attention on the short protocol for now, and to submit comments (or new text) before the end of November. Tossell will incorporate the comments and distribute a revised version of the protocol on December 7, 2001. Subgroup members should be prepared to comment on the revised version during the Subgroup's December 13 conference call.

COMMENTS ON THE SUBGROUP'S SHORT PROTOCOL

Bob Tossell said that the short protocol is about 50% complete. He asked whether it is headed in the right direction. Call participants agreed that it is, and offered the following suggestions:

• The short protocol should be completed soon. Harry Compton said that guidance on chlorinated solvents phytoremediation projects is long overdue. Call participants agreed to complete a draft of the short protocol by the end of the year, and to post a final version on the RTDF Web site by March 2002.



• Consider breaking the protocol into two sections. Xiujin Qiu recommended breaking the protocol into two major sections: (1) Assessment and Applicability, and (2) Implementation and Performance Monitoring.



• Add a decision tree flow chart. Qiu recommended adding a flow chart to lead readers through the phytoremediation assessment process. Tossell indicated that the Interstate Technology Regulatory Cooperation (ITRC) Work Group has created a decision tree; he asked Qiu to review the tree (located at www.itrcweb.org/phyto_1.pdf) and to create a shorter, more streamlined version for the Subgroup's short protocol.



• Include a conceptual model. Qiu suggested including a conceptual model, noting that it would help stakeholders understand phytoremedial processes.



• Incorporate water balance modeling. Qiu recommended providing information about water balance models, noting that these could be used to assess phytoremediation's ability to achieve hydraulic control. Tossell agreed that modeling is important, but said that information about water balance and ground-water models will be provided in the Subgroup's longer document. He suggested simply mentioning the models in the short protocol, and referring readers to the long protocol for additional information.



• Incorporate fate-and-transport modeling. Qiu recommended adding information about fate-and-transport models, which can be used to predict whether contaminants are likely to become incorporated into plant tissue or transpired and released to the air. Compton agreed that it is important to track contaminant fate, but questioned whether modeling is the best tool to use. As an alternative, he suggested using direct monitoring techniques.



• Provide information about phytotoxicity. Qiu said that it would be useful to provide information about contaminant concentration ranges that are toxic to plants.

COMMENTS ON THE SUBGROUP'S LONG DOCUMENT

Keith Rose offered the following suggestions:

• Reduce the "fuzziness" that currently appears in the document's "Screening Level Assessment Stage" and "Evaluation Stage" sections.



• Include a discussion about the dangers associated with monoculture techniques. Tossell said that phytoremediation strategies that use monocultures are vulnerable to disease. He suggested applying a broader "ecosystem approach."



• Make sure a flow chart appears in the "Screening Level Assessment Stage" section. Rose said that a flowchart has been created, but that it does not appear in the most recent version of the document. Tossell said that it will be inserted into the final version.