SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION OF ORGANICS ACTION TEAM
TCE IN GROUND WATER SUBGROUP
CONFERENCE CALL

July 13, 1998
3:00 p.m.­4:00 p.m.

On July 13, 1998, the following members of the Phytoremediation of Organics Action Team, Trichloroethylene (TCE) in Ground Water Subgroup, met in a conference call:

Greg Harvey, U.S. Air Force (Subgroup Co-Chair)
Harry Compton, U.S. Environmental Protection Agency (EPA) (Subgroup Co-Chair)
Dawn Carroll, EPA, Technology Innovation Office (TIO)
Larry Erickson, Kansas State University (KSU)
Milton Gordon, University of Washington School of Medicine
Lee Newman, University of Washington School of Medicine
Nishith Vasavada, Eastman Chemical Company (Eastman)

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

SELECTING A BROADER RANGE OF COMPOUNDS

Conference call participants recommended investigating a variety of contaminants rather than just TCE. Harry Compton said EPA has compiled a list of common ground-water contaminants. Dawn Carroll agreed to circulate the list to conference call participants.

COLLABORATING WITH THE DEPARTMENT OF ENERGY'S BIOMASS/BIOFUEL PROGRAM

During the June 11, 1998, conference call, Jerry Tuskan noted that the Department of Energy (DOE) has identified about 20 plant species (trees and grasses) with very high productivity. Tuskan noted that DOE has established plantations for some of these highly productive plants. Attachment A of the June 11, 1998, conference call summary provides additional information on DOE's plantations, including the (1) species, (2) genotype cultivar, (3) age of the study, (4) location of the study, (5) presence or absence of a lysimeter, (6) aboveground yields, and (7) propagation method.

Greg Harvey asked participants whether they had looked at Attachment A and which plants (e.g., eucalyptus, sycamore, hybrid willow, sweet gum, alder, ash, cottonwood, switch grass, reed canary grass) are most likely to be effective for phytoremediation. Unfortunately, several participants had not evaluated Attachment A before the call. One participant, Lee Newman, said that she never received a copy of the attachment. Harvey agreed to forward a copy to her. Harvey agreed to postpone the selection of the most promising plants until everyone has a copy of Attachment A. He encouraged participants to consider the switch and reed canary grasses. To date, he noted, neither grass has been examined for its phytoremedial value.

Once participants pick the five most promising plants, Harvey said phyto-based studies could be initiated. Newman recommended trying to get DOE to fund a portion of the studies, noting that DOE could benefit from phytoremedial technologies. (Participants said that halogenated hydrocarbons are at Hanford, Savannah River, and Oak Ridge National Laboratories.) Harvey said DOE has initiated some phyto-based research at Argonne Laboratories. Conference call participants agreed that Tuskan (DOE) and Ray Hinchman (Argonne Laboratories) should be contacted about additional DOE participation.

CONDUCTING TESTS

Compton said he sent Harvey and Newman a list of potential analytical tests. Harvey agreed to add information about geochemistry testing. Newman recommended adding ground-water modeling to the list. She agreed to give Compton information on ground-water modeling by mid-July. Newman said she is trying to obtain grant money for ground-water modeling. Originally, she said, her DOE contract included funding for this task, but it was later eliminated.

PHYTOREMEDIATION FOR CHLOROFORM PHYTOREMEDIATION/CONTAINMENT

Nishith Vasavada, a representative from Eastman, said his company is searching for alternatives to conventional pump-and-treat remediation. Vasavada said he is interested in innovative technologies that (1) control hydraulics and (2) remediate petroleum hydrocarbon-contaminated soil.

Vasavada said Eastman plans to plant trees early next year at a site in Texas. The site, Vasavada continued, has very low levels of chloroform contamination. Although Vasavada expressed interest in the phytoremedial properties of plants, he stressed that the goal at the Texas site is to contain the plume by controlling hydraulics. Vasavada asked for additional information on:

As a general rule, one participant noted, some investigators have suggested that plantations be 14 times larger than the area they are remediating. The participant was unsure, however, whether this general recommendation offers any practical use.

Harvey said he is working with the Forest Service to complete a model by next spring. He said the model will provide some insight but noted that predictions will rely heavily on site-specific information, climatic drivers, and soil-moisture release curves.

Vasavada said Eastman has used the GMS ground-water modeling software for rough estimates of the number of trees required. The software, he said, allows users to model well pumping rates under different conditions. Vasavada noted that tree performance can be roughly estimated using the model because a tree acts much like a well. Compton warned Vasavada to be careful using this approach, stressing the importance of considering seasonal and diurnal changes in pumping rates. Vasavada said these changes can be addressed in the software package.

Vasavada noted that Eastman is not an expert in the area of phytoremediation. He said Eastman has already contacted vendors for further guidance.

RECENT DRY-CLEANING SITE DEVELOPMENTS

Harvey said he is very interested in conducting phytoremediation field demonstrations at tetrachloroethylene (PERC)-contaminated dry-cleaning facilities. During the June 11, 1998, conference call, TIO's Richard Steimle noted that 10 to 12 states have expressed interest in using innovative technologies to remediate dry-cleaning sites. Steimle agreed to meet monthly with state representatives via conference calls starting in July. He also agreed to compile additional information about PERC-contaminated facilities. Harvey asked whether Steimle had made any progress. Carroll, Steimle's colleague, said that no additional information is available to date.

TIO INVOLVEMENT

Harvey noted that TIO has compiled a list of questions for the TCE Subgroup to answer (see Attachment A). For some of the questions, Harvey said, enough information is already available to formulate an answer. For others, there is not.

One question was whether phytoremediation can be used to remediate dense nonaqueous phase liquids (DNAPL). Both Harvey and Newman agreed that DNAPL will likely prove toxic to plants. Newman said she can nearly guarantee that trees will die if their roots penetrate DNAPL. She did note, however, that plants might survive if they are planted downgradient of DNAPL. With this scenario, she said, DNAPL could get flushed and dissipated as trees pull water from the capillary fringe. On a related topic, Harvey said contact with light nonaqueous phase liquids (LNAPLs) would probably also prove toxic. Newman agreed, stating that LNAPL would coat root hairs and suffocate trees. In summary, Harvey said, phytoremediation is not a logical remedial choice in situations where DNAPL or LNAPL is present as pure product. Compton agreed that this was probably true, but said he thought Jerry Schnoor is using trees at a BTEX site. The other conference call participants were unaware of this work.

Carroll said that TIO and the Office of Research and Development (i.e., Steve Rock) will hold a conference call at the end of July. Harvey asked that he and Compton be included in the call.

Harvey asked Carroll for information on potential funding. He noted that TIO has agreed to contribute funds to KSU on behalf of the Phytoremediation of Organics' TPH in Soil Subgroup and asked whether similar funding could be made available for the TCE in Ground Water Subgroup. Carroll said that a more concrete proposal of planned activities is needed before TIO will consider donating funds.

DEHALOGENASE ACTIVITIES

Harvey noted that Lazlo Martone (University of South Carolina) is examining the phytoremedial potential of marsh grasses. According to Harvey, Martone claims that marsh grasses along the eastern seaboard have extremely high dehalogenase levels.

Newman said that Mike Saunders is also analyzing the dehalogenase activities of marsh grasses. As part of his work, she continued, Saunders plans to test the accuracy of enzyme kits. Newman said that many people are evaluating enzyme activity using enzyme kits. Saunders plans to evaluate activity (1) using the kits and (2) performing time-intensive plant studies. After obtaining results from the two methods, she said, Saunders will indicate how well the two methods correlate. Newman said that she is glad Saunders is conducting this work. Although she has no information indicating that the kits are inaccurate, as a scientist she needs hard-core proof before she can gain confidence.

Harvey agreed that comparing the two methods is valuable. He said the Subgroup could conduct a similar comparison. He noted, however, that confidentiality issues make it difficult to get information about the enzyme kits. Harvey recommended doing a literature review and gathering existing information on halogenated hydrocarbons and plant materials and discussing the results in the fall. Newman agreed that this was a good idea and extremely worthwhile. She stressed that EPA regulators need solid data to feel comfortable blessing phytoremediation as a viable technology.

SUBGROUP MEETING

Harvey asked whether participants want to meet face-to-face in late fall or early winter. By then, he continued, preliminary results would likely be available for the Carswell site, an Army site in Orlando, Hill Air Force Base (AFB), as well as sites with which Newman and Compton are involved. Harvey recommended gathering available information before initiating more field demonstrations. Participants agreed that the meeting should be informal. The goal would be to create a proposal of future activities.

Conference call participants agreed that a meeting is a good idea. Harvey offered to hold it at Wright Patterson AFB in Ohio. In general, however, participants were more enthusiastic about having the meeting in Amherst, Massachusetts. Newman noted that a 4-day soil and ground-water conference is planned for October 19­22, 1998 in Amherst. She said she is planning to attend and thought Steve Rock was also. She recommended meeting informally sometime during those days. Newman said Denise Leonard (413-545-1239) could be contacted for information on conference registration fees.

MISCELLANEOUS

Compton said that committees associated with the Toxic Substances Control Act (TSCA) are establishing a working group to discuss transgenic plants and their implementation. According to some sources, Compton said, hybrids fall under the jurisdiction of transgenic plants. Harvey and Newman questioned this, stating that many hybrids form naturally without any human intervention. Compton said he would participate in the TSCA Working Group initially to determine how TSCA defines transgenic.

Harvey asked Carroll whether information can be gathered about people contacting the Web site. Carroll said she would talk to Environmental Management Support, Inc. (EMS) about this possibility.

ACTION ITEMS

NEXT CONFERENCE CALL

Harvey asked how often conference calls should be held. Newman recommended monthly calls so momentum is maintained. The next conference call is scheduled for August 10, 1998, between 3:00 p.m. and 4:00 p.m. (EDT). Harvey encouraged participants to e-mail him with suggestions for the call's agenda.

Attachment A

Questions From TIO

What is the fate of TCE?

What is the depth of efficacy?

What are the treatable concentrations?

How do DNAPLs act on the system?

What is really happening seasonally?

Are there other treatable contaminants (i.e., PERC or carbon tet)?

Are other types of vegetation applicable to phytoremediation?