SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION OF ORGANICS ACTION TEAM
VEGETATIVE CAP SUBGROUP
CONFERENCE CALL

August 14, 1997
11:00 a.m. to 12:30 p.m.


On August 14, 1997, members of the Phytoremediation of Organics Action Team, Vegetative Cap Subgroup, met in a conference call. The following members were present:

Tom Wong, Union Carbide Corporation (Subgroup Co-Chair)
Steven Rock, EPA/NRMRL (Subgroup Co-Chair)
Jeff Bowles, Dames and Moore (for Lucinda Jackson)
Felix Flechas, EPA/Region 8
John Fletcher, University of Oklahoma
Ray Hinchman, Argonne National Laboratory
Bruce Pivetz, ManTech Environmental Research Services Corporation
Phil Sayre, EPA/TIO

Also present was Jennifer Helmick of Eastern Research Group, Inc. (ERG).

SUGGESTED TOPICS AND SPEAKERS FOR THE SEPTEMBER 24-25 WORKSHOP

Tom Wong and Steve Rock stated that the purpose of the work sessions and case histories is to get everyone on the same page, and develop a common language and level of understanding, with respect to what is occurring in the phytoremediation world.

Several participants raised the question of whether there exists a core of vegetative cap examples with hard data. John Fletcher noted that he has observed that actual documentation of what happens at these sites is neglected. He noted that it might be worthwhile to talk not only about vegetative caps but about ecological processes to assist in theoretically identifying what happens. Ray Hinchman agreed, stating that Fletcher's work at the Chevron site should be considered, along with data on Ed Gatliff's sites. Hinchman stated that Gatliff should be asked to speak at the workshop.

Steve Rock proposed five presentations for the workshop: one by Tom Wong and John Fletcher, one on treatment units, one by Steve Dwyer on four different configurations at a DOE site, one on Warren Air Force Base, and one on modeling.

Participants noted that a key issue of this subject area is the lack of good predictive models. Tom Wong raised the possibility of bringing in an expert on the HELP model. This currently is the standard model for evaluating caps; it would be advantageous to adapt it for vegetative caps. Steve Rock noted that Paul Schroeder of the Army Corps of Engineers is interested in adapting the HELP model.

Tom Wong noted that key components that need to be addressed are 1) water balance issues, and 2) the pure phytoremediation portion (degradation of organic contaminants). The overall thrust is to reduce the flux of contaminants that eventually get into ground water. Steve Rock noted that the question has become bigger than just phytoremediation. Rock mentioned a meeting in Washington on August 13, where interest in alternative covers was evident at the EPA program office level.

The Subgroup then revisited the purpose of the workshop, with one participant questioning its title as an alternative cover workshop. It was noted that the subgroup is looking at the phytoremediation alternative. Steve Rock proposed that a purpose of the workshop be to address ways of assessing caps, looking at 1) treating wastes, and 2) excluding water or containing wastes. The remediation aspect is secondary to preventing infiltration.

John Fletcher returned to the question of case studies, noting that it is important to take a long-term perspective when assessing case studies. Studies of 3, 4, or even 10 years don't address the ultimate fate of contaminants. He stressed the need to look at legitimate case studies or projected ecological events.

Phil Sayre suggested that the advantages and disadvantages of traditional and vegetative caps be addressed. At the workshop, Dave Carson will discuss the design history of, and present-day concerns about, RCRA caps.

Steve Rock noted that we are at the point of technology where advantages and disadvantages cannot be quantified for regulatory purposes. With respect to operation and maintenance, it is only possible to speculate. While it appears that maintenance would be low, some history is necessary (considering such situations as when trees die and need to be replanted, or prairie or grass caps that may need to be burned).

Tom Wong then asked for other suggestions on topics and presenters. Bruce Pivetz mentioned several landfills in Oregon with poplars in the caps. Felix Flechas noted that this work is being done in conjunction with the firm CH2M Hill. He also recommended that Craig Benson present his work on performance of covers. Tom Wong noted that Lucinda Jackson's site in Richmond is intriguing.

Steve Rock expressed the hope that the workshop will consist of at least as much discussion as presentation time, so that attendees can put their experience on the table.

Phil Sayre asked whether Dave Carson's introductory talk will discuss the minimum requirements for a cap. Steve Rock responded that Carson will discuss RCRA equivalency. The introduction also will include a presentation on a generic vegetative cap, its function from a water balance and phytoremediation standpoint, and how the overall cap design achieves something similar to a RCRA cap.

Jeff Bowles asked about the extent to which the Subgroup is considering the differences between a landfill and a treatment unit (including with respect to regulatory issues). Subgroup members responded that the Subgroup is mainly addressing landfills, although some members have an interest in land treatment units. Tom Wong stated that the focus on where vegetative caps are used is not as important as regulatory acceptance. Jeff Bowles suggested that discussion of the regulatory framework would be useful. He reported that efforts are under way to look at ways of acheiving more active treatment at landfills through enhancing biological degradation.

Felix Flechas proposed that the workshop include a presentation about methane degradation in the rhizosphere. He noted that Susan Thorneloe is very concerned about methane production.

Several participants noted that regulatory issues keep surfacing in the Subgroup's disscussions, and that it might be appropriate to invite regulatory staff at EPA to address such regulatory policy issues as Subtitle D versus C caps and methane control. Tom Wong noted that a conflict that must be resolved is the requirement that a cap be no more permeable than the soil or liner below it. Steve Rock noted that the workshop is envisioned as a technical session. Phil Sayre suggested that one way to handle regulatory issues would be to interject them into Work Session 3 (Research Priorities).

RESEARCH PRIORITIES WORK SESSION

Steve Rock recommended that the workshop address available data and data needs, resources, and sites where testing could be performed.

The workshop should inform RTDF on how to proceed, and ideally will feed into Agency strategy development as well. Tom Wong stressed that workshop attendees should walk away with a concept for program development for RTDF: how RTDF is organized and function, and what each participant will contribute.

One participant suggested that the workshop break into small groups that discuss the same questions.


TASK FORCE WORK SESSION

Steve Rock recommended that workshop attendees in Work Session 4 (Task Force Work Session) be grouped according to topic areas (e.g., modeling, monitoring). In Work Session 4, a speaker will describe EPA Agreement structures, including how to handle different types of contributions and how to pursue other resources.

Phil Sayre asked if anyone will discuss agreements between companies. He suggested that someone from the Bioremediation Consortium (e.g., Dave Ellis) speak. He also asked whether the Subgroup will invite people who are not now participating but might be in the future. Steve Rock said that a variety of non-members, including Air Force personnel, were being invited.

Attendees will develop an action plan in the last session.

INVITATION LIST

Steve Rock described the invitee list (attached). He noted that invitations will not be broadcast but will be directed. The workshop is planned for about 30 people. Of those individuals invited so far, nearly all have accepted.

Other invitees proposed by the conference call participants included:

The conference call participants indicated whether they would be able to attend the workshop. All said they would or would try to, except Bruce Pivetz, who said he probably could not.

ACTION ITEMS