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

CONFERENCE CALL

August 17, 2000

1:30 p.m.-2:30 p.m.

On August 17, 2000, the following members of the Remediation Technologies Development Forum's (RTDF's) Phytoremediation Action Team, Chlorinated Solvents Subgroup, met in a conference call:

Bob Tossell, GeoSyntec Consultants (Subgroup Co-chair)
Steve Rock, U.S. Environmental Protection Agency (EPA) (Subgroup Co-chair)
Jim Jordahl, CH2M Hill, Inc.
Keith Rose, EPA (Subgroup Co-chair)
Steve McCutcheon, EPA

Also present was Michelle Arbogast of Eastern Research Group, Inc. (ERG).

THE SUBGROUP'S PROTOCOL

Bob Tossell described the goals and activities of the Chlorinated Solvents Subgroup. He also briefly summarized the sections of the Subgroup's protocol, outlining each section's status.

Comments on the Protocol

Tossell said that Keith Rose and Jim Jordahl submitted comments on the protocol. Most of the conference call was spent discussing these comments, which included:

• Shortening the microbial attenuation section (Section 2.3.5). Currently, the section is three pages long. One call participant suggested reducing it to about one page. Jordahl's written comments suggested describing microbial attenuation in greater detail in an appendix, but call participants agreed that it would be acceptable to explain microbial and anaerobic processes in the main body of the document. However, they agreed shortening the section would be appropriate.
  

• Enhancing the plant attenuation section (Section 2.3.6) to discuss the fate and transport of solvents. Tossell said that he plans to enhance this section after he receives the literature review from Lee Newman and Milton Gordon. This section is going to be three to five pages long once it is completed, so its length will balance that of the microbial section.
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One call participant suggested making the plant attenuation discussion stand alone rather than including it as a subsection of the fate and attenuation section. Call participants agreed that doing this would better emphasize the main topic of the protocol. The title of the section will be adjusted appropriately.

• Adding a subsection to Section 3 that addresses phytoremediation of solvents in soil. Call participants discussed plants' usefulness in remediating soil contamination and the limited information regarding that topic. They agreed that the protocol should include a brief section discussing phytoremediation of chlorinated solvents in soil. This discussion would incorporate two scenarios: residual saturation in a source zone and plume discharge to soil.
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• Identifying basic conditions needed for evaluating phytoremediation as a feasible option for source control or recharge control in Section 3 of the protocol. This section will discuss such topics as plant toxicity at high concentrations of chlorinated solvents, depth to ground-water requirements, root mass depth, and deep rooting techniques. Tossell will draft this section for the next meeting.
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The call participants briefly discussed the content of Section 3. They talked about the usefulness of plants in areas with high levels of chlorinated solvents and free-phase material (i.e., source areas). They also discussed the suggestion that roots avoid contaminated ground water when "clean" water is available. Different techniques for wet and dry climates and strategies to control surface recharge (e.g., clay layers and geomembranes) will also need to be further evaluated in this section.

• Providing examples in the polishing systems section (Section 2.4.2.5). Rose suggested giving examples of systems in operation or concepts in theory to demonstrate how the treatment chain and/or tertiary treatment system would work. Call participants agreed that this was a good suggestion.
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• Explaining practical limitations in the deep ground-water control section (Section 2.4.3.1). Call participants agreed that information about limitations should be added.

Other Work on the Protocol

Section 4, the section on screening processes, will address what data are needed for a preliminary review and will allow readers to determine if phytoremediation is appropriate for their sites. Section 4 will include the Interstate Technology Regulatory Cooperation (ITRC) Work Group's decision tree. As a courtesy, Tossell will inform Bob Mueller that the decision tree will be used in the protocol.

Tossell agreed to incorporate the comments into Sections 1 and 2, continue to write Section 3, and begin Section 4. Tossell agreed to send another draft to Subgroup members before beginning Section 4. He suggested that writing a detailed outline and then eliciting help from other committee members, as appropriate, would be a good use of the Subgroup's expertise. After Tossell drafts a detailed outline, he will ask for volunteers to write certain sections.

CONFERENCE CALL AGENDAS

Tossell asked the call participants if they thought an agenda would be a useful tool. Call participants said that it would, noting that having an agenda will inform members about what to expect in upcoming conference calls. They also suggested attaching the latest version of the protocol to the agenda. Tossell agreed to write an agenda for the next conference call.

ACTION ITEMS

• Steve Rock agreed to send a copy of the Subgroup's protocol to Steve McCutcheon via e-mail.
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• Tossell agreed to make the appropriate changes to Sections 1 and 2 of the protocol and send another draft to the Subgroup for comments. His work will include:
  

• Shortening the microbial attenuation section.

• Enhancing the plant attenuation section and making it a separate section.

• Adding a brief subsection to Section 3 that discusses phytoremediation of chlorinated solvents in soil.

• Adding examples of systems in progress or in concept to demonstrate how the treatment chain and/or tertiary treatment system would work.

• Explaining the limitations of deep ground-water control in Section 2.4.3.1.

• Continuing to write Section 3.

• Creating a detailed outline of Section 4.
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• Incorporating Jordahl's editorial comments.

• Tossell will inform Mueller that the ITRC's decision tree will be used in the protocol.
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• One call participant agreed to contact Newman or Gordon to check on the status of the protocol's literature review.
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• Jordahl agreed to send Subgroup members information about treatment wetlands.
  

• ERG agreed to include McCutcheon on the Subgroup's e-mail list.
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• ERG agreed to set up the next conference call for Thursday, September 14, 2000, at 1:30 p.m. Eastern Daylight Time. Tossell agreed to write an agenda for this call.