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

June 11, 1998
3:00 p.m.-4:00 p.m.

On June 11, 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)
Lee Newman, University of Washington School of Medicine
Steve Rock, EPA
Richard Steimle, EPA, TIO
Robert Tossell, Beak International, Inc.
Jerry Tuskan, Oak Ridge National Laboratories

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

EXPANDING THE FOCUS OF THE TCE SUBGROUP

Selecting a Broader Range of Compounds

Greg Harvey said that most phytoremedial studies have focused on TCE cleanup. Conference call participants recommended expanding the focus of future studies and investigating other contaminants that are commonly found in ground water (e.g., tetrachloroethylene [PERC] and trichloroethane [TCA]). One participant, Lee Newman, said that she has already started experimenting with other compounds. (Newman has established a field test in a 1,1,1-TCA contaminated site in Oregon and she expects to have metabolite data available soon.) Harvey said that the Agency for Toxic Substances and Disease Registry (ATSDR) has compiled a list of the most common ground-water contaminants. He suggested that the Subgroup focus their efforts on five to ten contaminants from the list. Harry Compton agreed to circulate ATSDR's list to conference call participants. (Dawn Carroll agreed to help him find the list.)

Collaborating With the Department of Energy (DOE)'s Biomass/Biofuel Program To Identify a Broader Range of Plant Species for Phytoremediation

Harvey said that cottonwoods and poplars have been used the most extensively in phytoremedial studies. These two species, he noted, do not grow well in all regions of the country. Several conference call participants recommended that studies be performed to (1) identify other plants that offer phytoremedial capabilities, and (2) determine which plants are most effective in different climatic regions. To accomplish these goals, Harvey and Jerry Tuskan suggested collaborating with the DOE's biomass/biofuels program.

Over the last 20 years, Tuskan said, DOE has screened about 200 plants (160 woody crop species and 40 herbaceous grasses) to determine which are the most productive in different regions of the country. Of the 200 plant species tested, DOE has identified 20 that have very high productivity rates (i.e., aboveground yields ranging from 3 to 10 dry tons per acre per year). Tuskan said DOE has established plantations for some of these highly productive plants. Some of these plantations, including those for sycamore, sweet gum, willow, black locust, and cottonwood, have ground-water monitoring systems installed on site. Tuskan stressed that DOE has not evaluated phytoremediation at the test plantations. To determine whether phytoremedial activities are ongoing, he said, the Subgroup could collect plant and ground-water samples from DOE's plantations. Attachment A 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.

Harvey expressed interest in learning more about the geochemistry of the areas underlying DOE's established plantations. He said he is particularly interested to find out whether ground-water geochemistry can be altered by microbial communities.

Harvey said he would like to screen some or all of the DOE's 20 species to determine whether the plants can degrade halogenated solvents. Conference call participants said a plant's remedial capabilities can be assessed by conducting:

• Specific enzyme assays. Harvey noted that assays can be performed to determine whether plants contain enzymes that degrade contaminants.
• General plant uptake and metabolism studies. Robert Tossell recommended performing fate and transport studies in a controlled laboratory setting. Newman agreed with Tossell's idea, noting that it is relatively quick and easy to trace a radio-labeled compound's passage through a plant.

Initially, Harvey suggested conducting just the enzyme assays. Newman, however, feared that the Subgroup could "get burned" by focusing solely on enzyme screening. She noted that there is no published data stating that scientists have correctly identified the enzymes that degrade halogenated solvents. Newman recommended performing enzyme assays and general plant uptake and metabolism studies concurrently. Using this approach, Newman noted, the Subgroup can try to correlate enzymatic activity with plant uptake and metabolism. Assuming that correlations are found, she said, the general plant uptake and metabolism studies might not be required in the future.

Assuming that the Subgroup decides to conduct plant analyses, conference call participants acknowledged, results will come from several different teams within the Subgroup. In fact, Harvey has already started testing willows, cottonwoods, sycamores, and eucalyptus in Texas; Newman has started testing alder, black locust, and willows in Washington. To generate meaningful and comparable data across team leaders, participants suggested:

• Identifying a central coordinating group. Compton recommended using a central coordinating group to organize the data that are submitted by various Subgroup participants.
• Endorsing a standardized protocol. Newman and Compton stressed that all participating laboratories should use the same soil, grow plants under identical conditions, administer identical contaminant concentrations, and monitor results using consistent procedures. Harvey and Newman have already drafted protocols and said they would be willing to share them with the Subgroup. Tossell asked conference call participants to send existing protocols to him so that he can compile a list. He said the Subgroup will need to decide whether to adopt an existing protocol or to create a new protocol.

Harvey asked participants to estimate the cost of conducting the plant analyses. Newman said it will depend on how comprehensive the Subgroup wants to be. The cost could be significant, she warned, if the Subgroup chooses to screen all 20 DOE plants for a dozen compounds. She said purchasing radio-labeled compounds can range in price from $1,000 to 20,000 per compound. Harvey and Compton advised asking TIO for financial support. Carroll agreed to talk to Walter Kovalick about funding issues.

RECENT DRY-CLEANING SITE DEVELOPMENTS

Richard Steimle said that he and Harvey have discussed the possibility of conducting phytoremediation field demonstrations at PERC-contaminated dry-cleaning facilities. Steimle said dry-cleaning remedial programs have been established in about 10 states. These states, Steimle continued, pay for the cleanup with a tax collected from the garment industry and other PERC users. Steimle estimated that there are about 1,500 to 3,000 sites that must be remediated. With such a large number of sites, Steimle stressed, states are eager to identify innovative technologies that offer better performance than conventional pump-and-treat systems. Some of the states (e.g., Florida) have already started to experiment with innovative technologies.

Steimle said that he will encourage state representatives to coordinate their innovative technology testing efforts. Steimle said he will try to convince state regulators that results can be extrapolated between states because dry-cleaning sites across the country have several things in common: (1) PERC contamination, (2) small-scale spills, and (3) industrialized locations. Steimle said flushing technologies and phytoremediation could prove useful for dry-cleaning facilities.

Newman noted that the Interstate Technology Regulatory Cooperation (ITRC) promotes shared information between states. States participating within the ITRC, she said, work together to promote innovative technologies. She agreed to give Harvey a contact name for the ITRC.

Harvey asked whether it would be possible to identify contaminated dry-cleaning sites that already have large trees located on site or downstream of the source. If so, Harvey continued, the Subgroup could collect samples to determine whether contaminants have attenuated in the trees. Steimle did not think that an effort of this kind had been initiated previously.

Steve Rock asked whether Harvey plans to target small shops (i.e., "Mom and Pop" establishments) or large disposal facilities (i.e., companies that clean dry-cleaning tools and dispose dry-cleaning waste). Harvey said the focus would be mostly on small shops. Newman said phytoremediation could prove useful at sites where contaminants are still isolated in the soil. At sites where the contaminants have reached the ground water, she warned, the majority of dry-cleaning facilities will not have enough land to support a plantation of trees. She suggested, therefore, that the Subgroup consider pursuing other types of PERC-contaminated sites rather than just dry-cleaning facilities.

Given land limitations, Steimle agreed that phytoremediation will be an impractical alternative for many dry-cleaning facilities. With 1,500 to 3,000 facilities in need of remediation, however, Steimle stressed that phytoremediation would be worth pursuing even if it proves useful for only a small percentage of sites. Steimle also noted that some cleanups will involve remediating areas downgradient of the dry-cleaning facility. In some cases, he said, the downgradient areas may have enough land to support a plantation.

Conference call participants agreed that additional information needs to be collected before they can determine whether field demonstrations can be established at dry-cleaning facilities. Participants said they need a list to determine (1) where dry-cleaning facilities are located, (2) how much empty space there is between the facilities and other buildings, (3) whether contaminants are located in the soil or the ground water, and (4) how fast contaminants are migrating. Steimle said that he plans to meet with state representatives via conference calls on a monthly basis starting in July. He said that he will identify available databases with relevant information. Steimle warned that some states will not have detailed databases because they have only recently been mandated to remediate dry-cleaning facilities. Harvey recommended telling state representatives that the Subgroup is searching for sites with plenty of land, existing vegetation, and PERC contamination in shallow, slow-moving ground water.

PROBLEM STATEMENT

Rock noted that the Subgroup identified two separate goals during the conference call:

• Identify additional plants and compounds that are applicable for the Subgroup.
• Identify dry-cleaning facilities that could serve as potential field demonstration sites.

Rock encouraged the conference call participants to prioritize their goals. Conference call participants expressed interest in achieving both goals. In general, however, more enthusiasm was stated for the former.

MISCELLANEOUS

In the near future, Newman said, she plans to release a report that summarizes the protocol and results for a site in Takoma, Washington.

Newman noted that she and Compton are working together on the Ambler Road West site. She said the site is contaminated with PERC and is located in Milwaukee, Oregon.

Harvey invited Tuskan to join the Subgroup. As a DOE representative, Tuskan explained that he is interested in phytoremediation. He noted that DOE is performing work in the Ukraine to determine how plants take up cesium and strontium.

ACTION ITEMS

• Tuskan agreed to provide additional information about DOE's plantations (See Attachment A).
• Carroll and Rock agreed to investigate the possibility of obtaining funds for the Subgroup.
• Tossell agreed to act as a clearinghouse for protocols. He said he would compile a list of currently available protocols before the next conference call.
• Steimle agreed to gather additional information on the locations and characteristics of dry-cleaning facilities.
• Compton agreed to distribute ATSDR's list of common ground-water contaminants to conference call participants.

NEXT CONFERENCE CALL

The next conference call is scheduled for July 13, 1998, between 3:00 p.m. and 4:00 p.m. (EST). Conference call participants agreed that they would like to hold conference calls on a monthly basis.

Attachment A

Species	Genotype cultivars	Age	Location	Ground-water lysimeters	Aboveground yield (tons/ac/yr)	Propagation method
Hybrid Poplar	4	10	WA	No	8-10	Cuttings
Hybrid Cottonwood	10	4-10	MN, WI, IA, ND, SD, MI	No	4-6	Cuttings
Eastern Cottonwood	8	4	SC	Yes	4-6	Cuttings
Sycamore	1	4	SC	Yes	3-5	Seedlings
Sweetgum	1	4	SC	Yes	2-3	Seedlings
Hybrid Willow	4	3	NY	Yes	7-10	Cuttings
Black Locust	6	8	GA	No	2-3	Cuttings
Silver Maple	10	5	IL, MN	No	2-4	Cuttings
Sycamore	1	4	TN	No	2-5	Seedlings
Sweetgum	1	4	AL	No	2-3	Seedlings
Switchgrass	3	1-5	AL, IA	??	3-10	Seed
Red Alder	1	10	TX, WA	No	2-4	Cuttings
Green Ash	-	-	Southeast	-	-	-
Eucalyptus	-	-	FL, CA, HI	-	-	-
Reed Canarygrass	-	-	PA, NY, VT, NH	-	-	-