SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
PHYTOREMEDIATION ACTION TEAM MEETING

Omni Parker House Hotel
Boston, Massachusetts
May 3, 2000

INTRODUCTION
Steve Rock, U.S. Environmental Protection Agency (EPA)

Steve Rock, one of the co-chairs for the Remediation Technologies Development Forum's (RTDF's) Phytoremediation Action Team, welcomed meeting attendees (see Attachment A). He said that three Subgroups have formed within the Action Team, and that each would give presentations and seek comments and input during the meeting. Rock said that each Subgroup is exploring a different way to apply phytoremediation. One is evaluating phytoremediation's potential to remediate total petroleum hydrocarbons (TPH) in surficial soils. Another is assessing vegetative caps as alternative landfill covers. The third Subgroup, which is just initiating activities, will evaluate phytoremedial systems at sites with chlorinated solvent contamination. Rock said that all three Subgroups have adopted the same general approach for their research: they are developing standardized (but flexible) protocols and inviting site managers/owners to test the protocols in the field. By using this approach, Rock said, the Subgroups will gain a better understanding of how phytoremediation performs across the country.

The Subgroups are composed of representatives from academia, government, and industry. Rock said that the Subgroups have a fairly informal organizational structure, but they all have three tiers of membership:

• Core group. The core consists of people who contribute significant time or resources to the Subgroup. This includes Subgroup co-chairs, site managers who are performing field studies, and people who play a key role in developing protocols or implementing field activities.

• Reviewers. Those who are interested in Subgroup activities but do not have sites to include in a field study program can stay closely involved by serving as reviewers for Subgroup products.

• Observers or interested parties. Those who do not want to participate actively in Subgroup activities can keep abreast of new developments by attending annual meetings and/or reading summary reports on Subgroup meetings and conference calls. (These summaries are available on the RTDF Web site at http://www.rtdf.org/public/phyto/minutes.) People in this group are on the RTDF mailing list; they receive announcements when meetings are scheduled and reports are released.

TPH IN SOIL SUBGROUP

Overview of the Subgroup's Composition, Goals, and Benefits
Phil Sayre, EPA

Phil Sayre, one of the co-chairs for the TPH in Soil Subgroup, opened the Subgroup's presentation by providing background information. (The other co-chair, Lucinda Jackson of Chevron Corporation, was unable to attend the meeting.) Sayre said that the Subgroup—formed in early 1998—is composed of representatives from major oil companies, universities, government, consulting groups, and the Petroleum Environmental Research Forum (PERF). Its main goal is to evaluate how effectively vegetation enhances the degradation of aged petroleum hydrocarbons in soil. Toward this end, Sayre said, the Subgroup has developed a standardized test protocol and has identified 11 sites that are willing to test phytoremediation in the field. Sayre said that site managers benefit from participating in the Subgroup because they receive:

• Regulatory input. Sayre said that the Subgroup's field test protocol was developed with regulators' input; thus, site managers who follow it can have some assurance that their field tests will be acceptable to the regulatory community.

• Discounted laboratory costs. Subgroup members are offered discounts on hydrocarbon analyses.

• Free formatting, analysis, and summarizing of data. Sayre said that the Great Plains Rocky Mountain Hazardous Substances Research Center (HSRC) provides a number of services to the Subgroup through its grant with EPA's Technology Innovation Office (TIO). For example, the HSRC collects the Subgroup's raw data from analytical laboratories, and then formats, analyzes, and summarizes these data. Sayre said that Peter Kulakow—a representative from Kansas State University—leads the HSRC's efforts to support the Subgroup.

• Immediate access to Subgroup data. The Subgroup's core members have access to data from all of the Subgroup sites. These data are not released to the public, though they will be in about two to four years.

The Subgroup's Protocol: Experimental Design and Sampling Plan
Phil Sayre, EPA
Peter Kulakow, Kansas State University

Over the course of several conference calls, Subgroup members created a field study protocol. (The protocol is posted on the RTDF Web site, http://www.rtdf.org; also, the issues debated during protocol development are posted at this site and can be found within conference call summary reports. The protocol was generated to ensure that comparable study designs and analytical procedures are used at all field sites. Sayre and Kulakow said that the protocol recommends testing three treatments:

• Standardized grass/legume mixture. Sayre said that the Subgroup has decided that a standardized grass/legume mixture should be tested at Subgroup sites to determine whether a standardized treatment can be used across the country. The mixture should be composed of 10% to 15% perennial or annual rye grass, 20% to 25% legume, and 60% to 70% fescue. (A large percentage of fescue is included because studies suggest that fescues are effective remediators.) At different sites, Kulakow noted, different species may be used to represent the three categories listed above.

• Local optimized treatment. Sayre said that the Subgroup recommends setting up plots containing native plants that thrive in the site's region.

• Unvegetated/unfertilized control. Over the course of several conference calls, Subgroup members have debated whether to fertilize unvegetated plots. (The vegetated plots described above will be fertilized as needed.) Subgroup members, Kulakow said, felt it would be ideal to test two types of unvegetated plots, one with fertilizer and one without. They knew, however, that most sites would only support one type because of budget and/or space constraints. When this is the case, they agreed, fertilizer should not be added to unvegetated plots. Kulakow admitted that using this approach will make it impossible for the Subgroup to determine whether adding plants to a system enhances contaminant degradation compared to using fertilizer alone. Subgroup members are fully aware of this, but decided to keep unvegetated plots unfertilized because it will allow them to answer the question that is most important to them: how does using phytoremediation (which includes plants, fertilizer, and irrigation) compare to doing nothing?

Kulakow said that the protocol indicates that (1) at least four replicates should be established for each treatment, (2) test plots should be at least 20 feet by 20 feet in size, (3) plots should be set up in a randomized block design, and (4) field studies should be conducted over at least three years. Expanding on the latter point, Kulakow noted that many Subgroup members want to extend the length of the study. Sayre said this is being discussed; efforts are underway to extend the grant that the Great Plains Rocky Mountain HSRC has with EPA's TIO.

Sayre and Kulakow said that the protocol indicates that several types of analyses must be conducted to evaluate phytoremediation. It outlines analyses for the following media:

• Plants. Investigators must assess above-ground biomass (shoot height and cover density), root depth, and root density to determine whether plants have established themselves successfully. Also, plant tissues must be analyzed for hydrocarbons to determine if there has been plant uptake.

• Soils. The protocol indicates that two composite samples should be collected from each test plot: one should be collected from shallow soils (0 to 15 centimeters), and the other from deeper layers (15 to 45 centimeters). (Each composite should represent a homogenized mixture collected from eight core samples.) Sayre and Kulakow said that the protocol lists the following as parameters that must be tested: agronomic conditions (e.g., nutrients, pH, and organic matter), TPH (using the modified EPA method 8015), polycyclic aromatic hydrocarbons (PAHs) and biomarkers (using the modified EPA method 8270), and hydrocarbon fractions (using the TPH Criteria Working Group, or TPHCWG, methodology). The protocol also lists other parameters that would be useful to assess, but that are not considered mandatory under the Subgroup's field program. These include microbial diversity, alkylated PAHs, and BTEX (benzene, toluene, ethylbenzene, and xylene). (Kulakow said that BTEX is not present at most of the Subgroup's sites.)

Sayre said that the protocol outlines a schedule of sampling events. Samples are to be collected before treatment plots are established (T_i), after seed bed preparation but before planting (T₀), and after each growing season (T₁, T₂, and T₃). He said that all of the analytical tests listed above do not have to be performed for each sampling event. The following table clarifies this:

Sampling Event	Matrix and Analysis	Purpose
Ti	Soil: TPH, PAH, biomarkers, TPHCWG, agronomic	Determine variability and which agronomic amendments to use. Determine where to establish plots.
T0	Soil: TPH, PAH, biomarkers, TPHCWG, microbial	Establish baseline.
T1(about 6 months after planting)	Soil: TPH, PAH, biomarkers, agronomic Plant: Growth parameters, species cover	Assess first season results.
T2 (about 18 months after planting)	Soil: TPH, PAH, biomarkers, agronomic Plant: Growth parameters, species cover	Assess second season results.
T3 (about 30 months after planting)	Soil: TPH, PAH, biomarkers, TPHCWG, agronomic, microbial Plant: Growth parameters, species cover, plant uptake	Assess third season results. Determine whether plant uptake occurred.

Kulakow stressed that the protocol is intended to serve as a useful framework, a model for people to follow when setting up a statistically valid experiment. He did say, however, that some Subgroup members are not following the protocol exactly. For example, at some sites, more than three treatments are being evaluated, but at another only two are being tested. Also, some sites have established more than four replicates per treatment, others are collecting samples from more than two depths, and some have combined the T_i and T₀ sampling events. Subgroup members feel that these variations are not a problem, as long as the Subgroup sites are all conducting statistically sound field tests and using appropriate analytical techniques. Following up on Kulakow's comment, Mike Reynolds (another Subgroup member) said that the protocol simply provides an ideal target. Having a target to aim for is important, he said, but Subgroup members are realistic: they understand that budget and site constraints may prevent members from following all aspects of the protocol. Kathy Banks, another Subgroup member, said that the flexibility that the Subgroup offers is very important to her. She said that she is often leery of standardized protocols, because she believes that investigators must be allowed to think creatively in the field. Before entering a site into the Subgroup's program, she said, she had to be assured that the protocol would not stifle her research or her efforts to pursue tests that are not currently listed in the protocol.

Description of Sites That Are Participating in the Subgroup's Field Study Program
Multiple Speakers

Eleven sites have been identified for the Subgroup's field study program, nine of which have already been planted. Kulakow said that the sites—labeled A through J—share at least one thing in common: they all have weathered petroleum hydrocarbon contaminants in their soil. The source of the contamination and the composition of the petroleum, however, differs from site to site. (Three sites were used as oil refineries, two were used as manufactured gas plants [MGP], one was an oil production site, and five had refined oils spilled onto them.) The Subgroup sites represent a wide range of climatic and environmental conditions. (Sites are located in Alaska, California, Arkansas, the Northeast, and the Midwest.) Kulakow and Sayre said that the Subgroup is glad to have such varied distribution, because it will help the Subgroup determine whether the standardized grass/legume mixture is effective across a variety of regions.

Sayre asked Subgroup members for information on the sites that they are working on. Attendees obliged; the information they provided is summarized below.

Site A

Kulakow said that Site A was formerly used as a refinery; sludge from the refining processes has impacted the site's soils. Treatment plots have been established at this site, he said, and T₀ and T₁ sampling events have been conducted.

Site B

Rock summarized Site B's history and status, described its experimental design, and discussed problems that have been encountered. He said that a heterogenous mixture of refinery wastes (e.g., tank bottoms, spill materials, and contaminated soils) were excavated from a refinery site, hauled to Site B, and spread on top of a confining clay layer. The site was land farmed for several years, he said; this involved adding urea once a year, tilling the site regularly during the growing season, and sowing the site with rye during the winter season. Rock said that Site B is currently designated as a closed RCRA site. It is still contaminated, however, so site managers will have to monitor it for 30 years unless they can demonstrate that the site is clean. Rock said that site managers hope that phytoremediation will clean up the site so that a "clean closure" designation can be obtained. Thus, a field test was initiated under the Subgroup's field study program.

Rock said that the contaminated soils sit on top of a clay-confining layer. The contaminants have stratified; shallow soils are cleaner than deeper soils, and a sludge layer is encountered on top of the clay layer. After evaluating the subsurface profile, Rock said, investigators decided that phytoremediation should be evaluated at three depths (0 to 6 inches, 6 to 18 inches, and 18 to 30 inches) rather than two.

Rock said that four treatments are being tested at Site B:

• Unvegetated/unfertilized control. Rock said that the control plots are being "hand turned" to keep them weed-free. (At most of the other Subgroup sites, an herbicide is being used instead.)

• Standardized grass/legume mixture. Rock said that rye grass was already prevalent at Site B when investigators arrived to establish treatment plots. This grass—one of the standardized mixture's components—was left in place and fescue and clover were planted on top of it. The rye is currently dominating the plots, Rock said. The fescue and clover did not compete well.

• Local optimized mixture. Rock said that poplar trees, willow trees, and a grass understory are being used in the local optimized mixture.

• Hackberry tree plot. Rock said that hackberry trees are being tested because one study indicates that hackberry root exudates perform effectively on Site B's PAHs.

Rock explained how trees were planted at Site B, how they are spaced, and what difficulties emerged during initial planting. The trees were planted, he said, by placing them directly into 3-foot-deep holes dug out with an auger. This ensured that the trees' roots would immediately contact the most contaminated portion of Site B. The trees are established, Rock said, in a 3-foot by 3-foot grid. (The trees were initially planted in a 6-foot by 3-foot grid, but site managers decided to double the tree density after reviewing work performed at other sites.) Rock said that a significant replanting effort was required at Site B, because about 50% of the trees that were initially planted died. A severe drought is partially responsible, he said, for this poor survival rate. (Site managers were reluctant to irrigate the site. Even though they agreed to truck in water later in the growing season, it arrived too late to save the trees.) Rock said that substandard planting techniques also contributed to the poor survival rates.

Rock's discussion on poor survival rates sparked input from meeting attendees, who described what they have learned about poplars. Lee Newman said that poplars tend to be invasive when planted on disturbed land, but that they have much greater difficulty becoming established if other plant species are already present. Thus, she said, it may be difficult to establish plots that have poplars and grass unless the former are established before the latter. Another participant said that brush blankets (small pieces of plastic) can help establish poplar whips. These blankets, he said, can be placed around the whips to keep grass away while the poplars become rooted and established.

Sites C, D, and E

Reynolds said that three phytoremediation demonstration projects have been established in Alaska. These sites, formerly operated by the Department of Defense (DOD), are on Native American lands. Information about these sites, Reynolds said, was provided in detail on the previous day at EPA's Phytoremediation State of the Science Conference. He said that nearly all of the RTDF meeting attendees were present at that conference; thus, he saw no need to repeat information about these sites.

Site F

Steve Geiger said that Site F, a former MGP site, has contaminated soil stockpiled in several locations. Some of this soil has been spread over the ground, he said, and phytoremedial treatments have been established. (Site owners did not initially plan to spread stockpiled soils over the ground. They decided to do so after finding that the area designated for field study had low contaminant concentrations.) Geiger said that the Subgroup's standardized grass/legume mixture is being tested at Site F, as well as a local optimized treatment that consists of a poplar/willow mixture. (The latter contains two different cultivars of poplar and seven cultivars of willow.) Geiger noted that willows were chosen for evaluation because the site owner is interested in the Department of Energy's (DOE's) efforts to promote willows for biomass reuse.

Site G

Kulakow said that Site G, a DOD site, has sediments that are contaminated with petroleum hydrocarbons. In fall 1999, he said, the sediments were excavated from a motor pool waste lagoon, spread over field plots, dried, sampled, and seeded. Three treatment plots have been established at this site: an unvegetated control, the Subgroup's standardized grass/legume mixture, and a local optimized treatment that consists of a native switchgrass.

Sites H and I

David Tsao provided updates for Sites H and I. Field activities have not yet been initiated at these sites, but Tsao hopes that samples will be collected and plants will be established in June 2000. While no foreseeable obstacles stand in the way of activities at Site I, it is not clear whether Tsao's proposed schedule will be met at Site H. In a recent e-mail, he learned that there might be some unresolved regulatory issues at the site; this could delay field activities and cause investigators to miss the planting season. Tsao said that this concerns him, because he knows the Subgroup may not be willing to accept new sites into the field study program for much longer. Tsao said that he was surprised to learn that regulatory concerns are still an issue at Site H; he was under the impression that permission had been granted to proceed with a phytoremedial demonstration project. Steve McCutcheon suggested contacting the Interstate Technology and Regulatory Cooperation (ITRC) Work Group and asking for help in resolving outstanding regulatory concerns. (ITRC's main goal is to reduce state regulatory barriers that prohibit the use of innovative technologies.)

Tsao talked about the T_i and T₀ sampling efforts that are planned at Sites H and I. He said investigators plan to skip the former at Site H, since the site is so small. At Site I, which is 55 acres in size, T_i sampling data must be collected to help investigators determine where to establish test plots. Although the Subgroup's protocol recommends collecting 20 samples during the T_i event, more will be collected at Site I. They will only be evaluated for TPH, however.

Before closing, Tsao noted that he had originally planned to perform microbial analyses at Sites H and I. Due to budget constraints, however, this is no longer possible.

Site K

Banks said that Site K, a former MGP site, has PAH contaminants about 3 to 6 feet below ground surface. Phytoremediation is being tested at this site, she noted, along with four other types of remedial systems: natural attenuation, land farming, compost treatments, and a bioslurry treatment. Each of the technologies, Banks said, has nine replicate plots. The plots that are being used to test phytoremediation contain poplars. This is the only vegetated treatment being tested; the Subgroup's standardized grass/legume mixture is not included in Site K's study design. Banks said that the poplars were planted in May 1999. They were chosen, in part, to draw down the high water level at Site K; investigators are hopeful that this will create a more aerobic zone in contaminated soil areas. Banks said that efforts have been initiated to establish a grass understory under the poplars. So far, this has been fairly unsuccessful, probably because the poplars provide so much shade. (The trees are spaced close together; each row of trees is about 3 feet apart, and the trees within each row are separated by about 3 feet. The trees might be thinned out in the future.)

Banks said that soil at Site K is sampled over three depths: 0 to 2 feet, 2 to 4 feet, and 4 to 6 feet. Several types of measurements will be used, she explained, to determine whether these soils are being remediated. For example, changes in contaminant concentrations, microbial diversity, and toxicity will be evaluated. (Some of the toxicity tests that will be used are documented in the literature; others are being developed through a grant that Purdue University has with EPA.) Banks said that it is too early to determine whether concentrations are changing at Site K, but some preliminary data do suggest that microbial diversity is changing and that soils are becoming less toxic to microbes and earthworms.

The Subgroup's First Annual Report
Peter Kulakow, Kansas State University

Kulakow said that the Subgroup's activities, data, and lessons learned will be summarized in a series of annual reports. The reports' format will follow the format developed by EPA's Federal Remediation Technologies Roundtable. That way, there will be consistency in how investigators present information about different remedial technologies.

Kulakow said that the first annual report was completed in March 2000; it contains a summary of T₀ soil data at five sites and plant assessment summaries at three sites. The report contains nine sections: (1) Executive Summary; (2) Introduction and Protocol; (3) Site Descriptions, which describes environmental conditions and experimental design; (4) Matrix Descriptions, which describes soil characteristics; (5) Status of Field Sites; (6) Summary of Plant Growth; (7) Cost Estimation, which describes methodologies for estimating the costs for demonstration and full-scale projects; (8) Regulatory Issues, which describes how approval was obtained for demonstration projects and provides information on the TPHCWG methodology; and (9) Issues Discussion, which summarizes discussions that the Subgroup has had on fertilization, mowing, plant species selection, microbial assessments, analytical methods, and integrating phyto- and bioremediation.

Kulakow said that the annual report contains about 50 data summary tables or graphs. He presented some of the data that have been collected on TPH, priority pollutant PAHs, and benzo(a)pyrene equivalents. In addition, he provided information on:

• Environmental conditions. Kulakow said that data on environmental conditions have been collected from local weather stations near each of the Subgroup's sites. He presented data on average annual rainfall and maximum, minimum, and average temperatures for all 11 Subgroup sites. Values recorded ranged dramatically. For example, while average annual rainfall was about 5 inches per year at one site, it was more than 100 inches per year at another. As for temperatures, while maximum temperatures never exceed 0 degrees Celsius ( C) at one site, they reach beyond 20 C at another. Mike van Bavel—one of the meeting attendees—asked Kulakow whether the Subgroup had considered irrigating sites that receive less than 40 inches of rainfall each year. Kulakow said that the Subgroup encourages irrigation if it is needed to get plants established. In full-scale applications, however, site managers will be reluctant to irrigate regularly. Another participant asked whether any soil sensors have been established to measure soil moisture or soil temperature. Kulakow said that this is not a mandatory part of the monitoring scheme, but that soil temperature is measured intermittently at Sites C, D, and E. van Bavel said that Dynamax, Inc., could probably provide soil sensors at low cost. Kulakow said that Subgroup members might discuss this offer during their next conference call.

• T₁ root growth data. Kulakow said that plant assessments were conducted at the end of the first growing season at three sites. He presented data on root length density (measured in millimeters per milliliter) for the standardized grass/legume mixture and the local optimized mixture. He gave this information for two different depths, 0 to 15 centimeters and 15 to 30 centimeters. At some sites, he said, the values recorded do not just represent root growth during the phytoremedial test project; they also represent historic roots—remnants of plants that were growing at the site before the Subgroup's field activities were initiated.

Kulakow said that all of the data presented in the first annual report will eventually be made available to the general public. At this point, however, the report, with all of its site-specific data, is only being distributed to core Subgroup members. This is because PERF (one of the Subgroup's members) has a policy that requires site-specific data to be protected for two to three years. However, Kulakow said, a less detailed version of the report will be produced and released to the public over the summer. (Much of the site-specific data will be removed from this version.)

Kulakow's closing comments sparked comments from the audience. Fiedler recommended having the annual report peer-reviewed. She also asked whether site names will be provided in the version that is released to the public. Kulakow said that he planned to refer to the sites as Sites A through J rather than using their real names. Fiedler questioned whether this was necessary for all of the sites; for the sake of technology transfer, she said, it would be useful for people to know where technologies are being tested. She said that she understood that some site managers might ask for anonymity at this point, but thought that information on Site G, which is a DOD site, could probably be released immediately. She recommended using the following approach in the report: list some sites under their code names, but use actual site names for those that do not require anonymity.

Regulatory Perspective
Bob Mueller, New Jersey Department of Environmental Protection
Felix Flechas, EPA's Region 8

Sayre said that the Subgroup's field projects are being performed, in part, to address regulatory concerns. (If promising data are generated in the field, regulators will be more likely to grant approval for phytoremedial technologies.) Sayre asked two regulators—Bob Mueller and Felix Flechas—to identify some of the questions that they want addressed. The two regulators listed the following:

• Contaminant byproducts. Mueller said that regulators want information about byproducts that form when contaminants are treated by plants. (In some cases, these byproducts can be more toxic than the parent compound.)

• Ecological risks. Mueller said that some regulators are concerned that phytoremediation could cause ecological risks. They feel that contaminants might be incorporated into plant tissues, which could in turn be ingested by animals (e.g., insects and rabbits).

• Managing plant waste. Flechas said that studies indicate that some contaminants accumulate in plant leaves and roots without degrading. As a result, the ultimate fate of contaminated plant tissues concerns many regulators, especially when metals or radionuclides are present at a site. (Although the TPH in Soil Subgroup is not focusing on metals and radionuclides, these contaminants were discussed, along with organics, in order to present a more comprehensive discussion of the regulatory concerns that surround plant waste management issues.) Flechas presented an overview of the regulations that influence how plant wastes must be managed. He said that the approach used will differ significantly depending on a site's status:
  
  

  —	Sites with listed hazardous waste. If a phytoremediation project is established at a site that has listed hazardous waste, Flechas said, then all of the treatment residuals (i.e., plants) are considered listed hazardous waste and must be managed as such. This means that site managers might be required to ship the materials to a hazardous waste disposal facility. As an alternative, Flechas said, regulators might allow site managers to dispose of treatment residuals in a Corrective Action Management Unit (CAMU). (Flechas said that it is not yet clear how enthusiastically EPA, as a whole, will embrace CAMUs. The concept is currently being presented and discussed throughout the Agency. More decisive information about EPA's stance will probably be released in summer 2000.) Milton Gordon (a meeting attendee) noted that studies have been performed using poplars to remediate chlorinated solvents. The results, he said, indicate that parent compounds are not present in the poplar tissues. In a case like this, Gordon asked, would the poplars still be considered listed waste? Flechas said they would, under current regulations. He did note, however, that it might be possible to delist an actual treatment process if enough data are generated to prove that contaminants are not accumulating within plant tissues at unacceptable levels. Fiedler questioned whether phytoremedial processes could be delisted, since there is such variation in how different contaminants behave in plants. Flechas agreed that it would not be possible to simply delist all phytoremedial processes for all contaminants. Instead, he suggested pursuing very specific processes. For example, if enough data become available, it might be possible to say: if contaminant x is treated by plant y, then plant residuals will not be considered listed hazardous waste. Fiedler said that TIO might want to work with EPA's Office of Solid Waste and Emergency Response to discuss how to regulate treatment residuals that are generated from listed hazardous waste.
  —	Sites with "characteristic" waste. If a site is designated as having characteristic waste, Flechas said, sampling is conducted to determine how treatment residuals should be managed. If they are shown to be less contaminated than characteristic sources, they are considered nonhazardous and may be disposed of in a sanitary waste landfill.

  To date, Flechas said, offsite disposal and burning appear to be the approaches that are most commonly used to manage plant wastes. He questioned whether these are the best approaches, noting that the former can be very costly and that the latter, which simply concentrates contaminants, can create dangerous air emissions. He recommended brainstorming to identify other potential solutions. For example, he said, maybe some consideration should be given to simply turning plant wastes back into the ground. Doing so, he said, might enhance the overall productivity of the entire field. Flechas said that such an approach might be a viable solution at sites that have organic contaminants, but he was not sure it would be viable for sites contaminated with inorganics. He said that more information is needed on the fate of metals to determine whether they can be extracted from plant tissues. Linda Fiedler was opposed to turning metal-contaminated plants back into the soil. She said that it is challenging to remove inorganics from soil; she did not think they should be redeposited. Another meeting participant also questioned Flechas' proposed alternative, but did agree with his main point: alternatives to offsite disposal and burning should be investigated. (She said that the University of Florida is conducting studies to determine whether a gas fixation process can be used to extract metals and simultaneously produce energy.)

• Contingency plans. Mueller said that regulators want to see contingency plans incorporated into phytoremediation proposals. These will need to explain what will be done if plant systems are destroyed or compromised by hurricane, animal invasion, droughts, or fires.

• Lack of performance data. Mueller said that several laboratory and greenhouse studies have been performed to assess phytoremediation, but that relatively few field trials have been conducted. More field data are needed to convince regulators that phytoremediation is a viable and effective remedial approach. (He noted that the Subgroup's effort will help address this concern.)

• Statistical significance of changes detected in the field. In order to be convinced that phytoremediation is working, Flechas said, regulators will need to be assured that changes detected in the field are statistically significant. He encouraged investigators to collect detailed baseline information about sites so that they understand their contamination distributions before initiating a phytoremedial project. Without this information, he said, it is difficult (if not impossible) to determine whether changes represent anomalies or statistically significant changes. Flechas said that Dr. Schwab has prepared guidance that explains how to design field experiments so that they generate statistically significant data. Kulakow said that Schwab's guidance has been incorporated into the work plan for Site G; this guidance will be made available to a wider audience soon. In addition, Flechas said, one of EPA's contractors has drafted some suggestions.

Geiger asked Mueller and Flechas to explain what site managers should do to obtain regulatory approval for phytoremediation projects. If the site is state-led, Mueller said, ITRC may be able to help facilitate approval. After proposing phytoremediation to a state agency, Mueller said, site managers should let ITRC know that the proposal has been made. As a followup, he said, ITRC will send information about itself to the state agency, along with a contact name. If the site is led by one of EPA's regional offices, Flechas said, site managers should: (1) gather information on phytoremediation projects that have been conducted by TIO or the Office of Research and Development, and (2) present these educational materials to regulators.

ITRC Phytoremediation Decision Tree
David Tsao, BP Amoco

Tsao said that ITRC's Phytoremediation Work Group has created a 40-page document to help site managers determine whether phytoremediation is a reasonable approach to use at their sites. (The document can be downloaded from http://www.itrcweb.org. An interactive version is available at http://www/eas/battelle.org/dev/phyto/index.htm.) The document, Tsao said, was written by a team of 12 people, including representatives from state agencies, EPA, and private industry. It contains flow diagrams that present a series of "yes or no" questions. Depending on the user's responses to these questions, Tsao explained, he or she will eventually be led to one of the following conclusions: (1) phytoremediation could be effective at their site, or (2) phytoremediation is not an option at their site. Tsao said that the flow diagrams present the decision-making process in a concise fashion. The questions force site managers to consider the following when trying to decide if phytoremediation is suitable at their sites: climate, space constraints, time constraints, contaminant depth and concentration, fate and transport processes, regulatory issues, and design compatibility. More detailed information about these key considerations is provided, Tsao said, in the text that accompanies the flow diagrams.

Tsao noted that phytoremediation can be used to clean up a variety of media. Because of this, ITRC created separate flow diagrams to assess phytoremediation for applications in soil, sediment, and ground water (see Attachment B). He presented the flow diagram for soils and described it in some detail. The first questions posed, Tsao said, ask whether plants can grow in the site's climate, whether time or space constraints exist, whether contaminants are present at phytotoxic levels, and whether the contaminants are located within plant root zones. After these questions are addressed, he said, the flow diagram asks: Will the rhizosphere microbes and plant-exuded enzymes degrade the target contaminants in the rhizosphere, and are the metabolic products acceptable? If the user answers "yes," the flow diagram concludes that phytoremediation could be effective at the site. If the answer is "no" or if users simply do not know the answer, then a series of additional questions must be answered about the contaminant's log K_ow, its likelihood to accumulate in plant tissues, and its ability to transpire. Depending on how these questions are answered, Tsao said, the flow diagram asks users about the acceptability of transpiration rates or accumulation levels. If levels are unacceptable, Tsao said, users must determine whether there are controls that can alter transpiration rates, immobilize contaminants, or prevent plant materials from being transferred to humans and animals. After all of these questions are addressed, if phytoremediation still appears to be a candidate, users must determine whether plant waste will be considered hazardous and whether it can be disposed of economically. Tsao showed meeting attendees how the flow diagram leads to the conclusion that the Subgroup's standardized grass/legume mixture is a viable approach to test at the Subgroup's sites.

Tsao stressed that the decision tree is only intended to serve as a screening tool. If, after going through one of the flow diagrams, site managers conclude that phytoremediation is a reasonable option, they should follow up with a more rigorous assessment before making a final decision. Tsao said that ITRC is writing a document that will guide site managers through this part of the process. This manuscript, a technical and regulatory guidance document, is scheduled for release in July 2000. It will provide specific guidance on how to assess phytoremediation's potential in soil, sediment, surface water, and ground water that are contaminated with organics or inorganics. It will also contain detailed descriptions of the mechanisms that underlie phytoremediation and the different ways the technology can be applied. Mueller—one of ITRC's leaders—said that the document will also discuss regulatory concerns in detail. The document will acknowledge that phytoremediation has limitations, but that it often offers enough benefits to make it worthwhile. McCutcheon asked whether the document will address regulatory barriers that prevent phytoremedial systems from being installed in wetland areas. Mueller said that constructed wetlands will be addressed in ITRC's technical and regulatory document.

Analytical Tests Used to Evaluate Phytoremediation at Petroleum-Contaminated Sites
Henry Camp, Arthur D. Little

Henry Camp opened his presentation by summarizing the issues that Subgroup members had to consider when drafting a sampling and analysis plan:

• Degradation occurs slowly and subtly. Camp said that phytoremedial systems induce changes in contaminant concentration and composition, but that these changes occur gradually and subtly. He said that it is important to document changes, because regulators will want to know whether contaminants are being reduced below regulatory standards. In addition, from a scientific point of view, it is important to document changes in composition, because the toxicity of a petroleum-contaminated material is contingent on the composition of its hydrocarbon profile.

• Monitoring must be conducted over a long period. In order to fully assess a phytoremedial system's performance, Camp said, samples must be monitored over a long period of time. Thus, sampling and analytical plans should be designed to ensure that consistent techniques and quality control procedures are used throughout the course of a study. Without this consistency, inherent analytical variability will compound over time, and this will make it difficult to interpret analytical results. Camp said that the Subgroup has taken great efforts to think about their long-term data collection needs. The Subgroup even decided, Camp said, to store frozen soils in case they want to evaluate a new parameter in the future.

• Contaminants are not distributed evenly throughout the matrix. Petroleum-contaminated sites rarely have contaminants distributed evenly throughout their soils. This appears to be the case, Camp said, even when sites are tilled, mixed, and homogenized. To demonstrate his point, Camp presented chromatograms for one Subgroup site: these showed that petroleum was heavily degraded in one portion of the site, but not at another. For another Subgroup site, he presented photographs that documented plant growth. He noted that growth was not equally robust in all areas. While erosion of topsoil could be partly to blame, he said, variations in contaminant concentrations are probably also responsible for this distribution pattern. Because there is such variation between individual sites, Camp said, it can be difficult to determine when detected changes in concentration are statistically significant.

Camp described the limitations of using conventional laboratory techniques to evaluate TPH. Such techniques provide no information on contaminant composition; they simply measure TPH concentrations. Also, conventional analytical techniques often have significant analytical variability. This can obscure subtle changes that occur in the field. When assessing phytoremediation at petroleum-contaminated sites, Camp said, more advanced analytical methods should be used, so that the data produced are very accurate and precise.

Camp described the analytical methods that are being used at the Subgroup's sites. He said that TPH is being measured using a gas chromatography (GC)/flame ionization detector (FID), and that biomarkers and PAHs are measured using GC/mass spectrometry (MS). Camp said that these techniques are very sensitive; in fact, the GC/MS method can detect PAHs at trace levels. The results obtained in the laboratory, he said, can be used to evaluate total oil content, view individual petroleum constituents, and evaluate changes in composition over time.

Camp reiterated a point that he made earlier in his presentation: significant variability often exists at petroleum-contaminated sites. He said that this can be addressed using biomarkers. These compounds, which are highly resistant to degradation, remain in soil samples even after other petroleum constituents have degraded. Thus, biomarkers can serve as conservative internal markers and can be used to normalize data. Camp, citing the following equation, said that biomarkers can be used to calculate how much oil depletes over time:

Total oil depletion over a specified amount of time

= (1 H0/H1) x 100

In this equation, Camp said, H₀ represents the biomarker concentration in the source oil and H₁ represents the biomarker analyte concentration in the degraded oil. Biomarker concentrations within a sample increase over time, he said, noting that the amount of biomarker stays the same as other constituents within a petroleum source degrade. He said that all of the terms that are used in the above equation should be expressed in an oil weight basis. Thus, for the Subgroup's sites, the concentration of the biomarker would be expressed based on 100 milligrams of oil, not on a certain quantity of soil.

Camp said that hopane is often used as a biomarker. It is usually detected at sites that are contaminated with crude oils, but it is not always present at sites that have more refined wastes (e.g., MGP sites). If hopane is not present, he said, other recalcitrant constituents can be used to normalize data. For example, he said, in some cases, data have been normalized by comparing the ratios of individual PAHs against the sum of more recalcitrant PAHs. (Camp said that the PAHs were not as recalcitrant as biomarkers, but they were still more resistant to degradation than other petroleum constituents. He said that investigators chose to sum the recalcitrant PAHs rather than using an individual constituent because it helped eliminate some analytical variability.)

Before closing, Camp reviewed the parameters that are included in the Subgroup's protocol: agronomic conditions, TPH, PAHs, biomarkers, hydrocarbon fractions (via the TPHCWG methodology), alkyl PAHs, BTEX, and microbial analyses. (The last three are optional.) He praised the Subgroup for their comprehensive analytical plan. He said that it has been set up to keep analytical costs down, to encourage flexibility, to reduce variability, to facilitate comparisons across sites, and to evaluate treatment mechanisms and treatment efficacy. Expanding on the latter, Camp explained that efficacy can be evaluated using two different approaches: (1) assessing contaminant reductions and (2) evaluating how changes in composition impact human health or ecological risks. He said that the latter approach will be particularly important to use at sites that have low TPH values, but high PAH concentrations. He said that at least two of the Subgroup's sites (a former MGP site and a former refinery site) fit this profile.

Meeting attendees asked about the following when Camp finished his presentation:

• Interference. Flechas asked a hypothetical question: If a sample contains petroleum in the 1% range and benzo(a)pyrene at 100 parts per million (ppm), will the latter be detected? Camp said that it would, noting that the analytical tests that are being used to assess Subgroup samples incorporate several cleanup techniques.

• Sample size. In response to a question from the audience, Camp said that 30-milligram samples are used in the laboratory. Larry Erickson asked why 30 milligrams had been chosen as the sample size. Camp said that he thinks EPA recommends this as a minimal sample size.

The TPHCWG Methodology
Steve Geiger, ThermoRetec, Inc.

Geiger opened his presentation by explaining why he advocates using the TPHCWG methodology. This method—developed by representatives from academia, industry, and the Air Force Center for Environmental Excellence—can be used to generate site-specific TPH cleanup levels. He said that it is preferable, from a scientific and practical point of view, to use these levels rather than prescribed state or national standards because:

• Risks posed by TPH exposures vary significantly across sites. Geiger noted that there are more than 100,000 different compounds present in crude oil. Although toxicological studies have only been conducted on about 40 to 50 of these constituents, enough data have been collected to show that hydrocarbons exhibit a wide range of toxicological effect. Some are highly toxic, some are more benign, some pose carcinogenic risks, and others pose noncarcinogenic hazards. Thus, the potential risks associated with TPH exposure at a given site are determined by the composition of the specific petroleum product that is present.

• Current TPH standards are arbitrarily derived and fairly low. Geiger said that several states have established TPH standards, but that most of these have been derived arbitrarily rather than through risk-based methodologies. Thus, the most important considerations—protection of human health and the environment—were not the driving forces behind setting the standards. He said that the standards cited across the country vary dramatically. Demonstrating this point, he presented a graph that showed the gasoline TPH cleanup levels that have been established across the country. Concentrations cited ranged from less than 10 ppm (Maine) to greater than 10,000 ppm (Arizona). Geiger said that phytoremedial systems may not be able to achieve the low levels that have been established in some states. He questioned whether the technology should be penalized for this, since the standards represent arbitrary numbers. He thought it made more sense to set endpoints that are risk-based; some regulators agree with this, and are willing to use risk-based cleanup levels to assess phytoremediation's efficacy.

• Cleanup levels derived from the TPHCWG approach provide realistic cleanup goals that are easy to verify in the field.

Geiger provided a brief overview of the TPHCWG methodology, noting that the process involves using the Direct Analysis Procedure to separate TPH extracts into numerous aliphatic and aromatic fractions. He said that each fraction contains several compounds that are grouped together based on carbon number and behavioral characteristics (e.g., leaching and volatilization). Toxicological information is assigned to each fraction based on surrogate compounds. (If toxicological information is available for more than one constituent within a fraction, investigators assume that the entire fraction represents the most toxic compound.) Once the toxicity of each fraction is estimated, Geiger said, investigators calculate acceptable risk-based cleanup levels. They do this by setting hazard quotients to 1.0, then using risk assessment calculations to determine how much contamination can be allowed without pushing overall risk over 1.0.

Geiger stressed that the TPHCWG methodology should only be used at sites where noncarcinogenic PAHs are the main risk drivers; it is not appropriate for sites where carcinogenic PAH concentrations exceed Tier I screening criteria. Geiger said that benzo(a)pyrene (a carcinogen) poses unacceptable risks at the Subgroup's Site F; thus, the TPHCWG methodology is not being used at this site. At Site G, however, the TPHCWG methodology has been a useful tool. Geiger said that spreadsheets were used to calculate site-specific cleanup levels at Site G based on potential risks posed through soil ingestion, leaching to groundwater, and volatilization. (Geiger said that the spreadsheets that were used are a bit outdated. Recently, the TPHCWG released revised spreadsheets that address additional exposure pathways.)

Geiger presented the spreadsheets that were used at Site G and explained the steps that were taken to define site-specific cleanup levels. These steps are presented in the following table, along with information about the results obtained and the cleanup levels established.

TPHCWG Methodology As Applied at Site G: Procedure, Results, and Conclusions

Generating TPH data Samples were analyzed using the Direct Analysis Procedure. This provided information on (1) PAH concentrations and (2) hydrocarbon fractions. (The TPH was separated into numerous aliphatic and aromatic fractions, each of which contains several compounds that are grouped together based on carbon number and behavioral characteristics.) Results indicated that Site G's soils are weathered; most of the lighter-end hydrocarbons have already been degraded.

Screening carcinogenic PAHs to determine whether to proceed with the TPHCWG methodology Carcinogenic PAH concentrations in the surface soil and subsurface soil were compared to Tier I screening criteria. (Mean and maximum concentrations were compared to EPA's Region III risk-based concentrations.) Screening criteria were provided for several scenarios: (1) soil ingestion in an industrial setting, (2) soil ingestion in a residential setting, (3) and ground-water migration. Benzo(b)fluoranthene and benzo(a)pyrene exceeded the criteria, but only under the residential scenario. If the site were reused as a residential area, then the TPHCWG methodology would not be applied, because the carcinogenic PAHs would drive risk and cleanup decisions. At Site G, however, it was assumed that institutional measures (e.g., deed restrictions preventing residential reuse) will be established so that the site's future use will be industrial. Thus, since none of the carcinogenic PAH concentrations exceeded industrial criteria, the decision was made to calculate site-specific cleanup levels based on noncarcinogenic PAHs.

Evaluating toxicity and identifying input parameters Toxicity values were assigned to the hydrocarbon fractions. Input parameters for risk-based corrective action (RBCA) calculations were gathered. (The inputs selected were default values that had been published in the literature. Inputs that were needed for Site G's risk assessment included averaging time, body weight, exposure duration, exposure frequency, ingestion rates, leaching factors, ground-water mixing zone thicknesses, and ambient air mixing zone height.)

Using RBCA worksheets to generate site-specific cleanup levels A risk assessment worksheet was used to assess the risks that noncarcinogenic PAHs could pose through soil ingestion, ground-water migration, and volatilization. First, input parameters and site-specific data were entered on the worksheet. Then, for each pathway, the hazard quotients for the fractions were set to 1, and calculations were performed to determine how high contaminant levels could be without exceeding the hazard quotient. The results indicated that the following cleanup levels would be appropriate to use under an industrial use scenario:   Leaching Pathway Inhalation Pathway Ingestion Pathway         Surface Soil: 247,187 ppm 26,144,553 ppm 14,126 ppm Subsurface Soil: 127,664 ppm 13,072,276 ppm 10, 163 ppm Investigators decided that the values calculated under the ingestion pathway are the most appropriate to use as site-specific cleanup goals at Site G. Because surface soil is only about 8 inches deep at the site, it would not be difficult for individuals to expose the subsurface. Thus, the decision was made to use 10,163 ppm (the more conservative value) as the site-specific cleanup goal.

In summary, Geiger said, a site-specific cleanup goal of 10,163 ppm was calculated for Site G using the TPHCWG methodology. Although this is higher than the standards that have been established in many states, Geiger said, it may be an acceptable target for Site G since it was generated based on a scientifically valid process that is designed to protect human health.

Before closing his talk, Geiger presented data to show how close Site G is to meeting the 10,163-ppm cleanup goal. He said that available data provide conflicting information. When TPH is measured using GC/FID or gravimetric methods, he said, concentrations in the surface and subsurface soils are recorded as being above the cleanup level. (They range between about 13,000 and 15,000 ppm). However, when TPH is measured using TPHCWG methodologies, the values fall below the cleanup values, ranging between 1,000 and 4,000 ppm.

THE CHLORINATED SOLVENTS SUBGROUP
Robert Tossell, GeoSyntec Consultants

Robert Tossell, one of the co-chairs for the Chlorinated Solvents Subgroup, began by saying said that his Subgroup was formerly known as the Trichloroethylene (TCE) in Ground Water Subgroup. About six months ago, however, Subgroup members decided to broaden the Subgroup's scope to address a wider variety of media and contaminants. Accordingly, the name has been changed to the Chlorinated Solvents Subgroup. In addition, a new mission statement has been written: To advance the knowledge, development, and application of phytoremediation of chlorinated solvents in soil, ground water, and surface water. (Tossell said that the mission statement uses the term "chlorinated solvents" because these will be the Subgroup's main focus. However, the Subgroup will also consider evaluating phytoremedial systems at sites that have brominated compounds.)

Tossell said that the Subgroup has identified four goals. Subgroup members aim to (1) further the development and efficacy of phytoremediation for chlorinated solvents, (2) develop a protocol for the application of phytoremediation at sites with chlorinated solvents, (3) "test drive" the protocol at one or more sites, and (4) update the protocol based on field tests. By pursuing these goals, Subgroup members hope to be able to develop a proof of concept, identify the technology's limitations, compare the benefits and costs to those incurred using other technologies, formulate strong evidence that can be used to overcome skepticism, and define the best ways to use phytoremediation (e.g., as part of a treatment train).

Tossell summarized what has already been learned about phytoremedial systems that are used to treat chlorinated solvents. He said that various plants and algae have been evaluated to determine how effectively they degrade contaminants. (In some of the studies, he said, kinetic degradation rates have actually been calculated.) Tossell said that studies indicate that contaminant degradation can occur by a number of mechanisms. Some of these (e.g., bioremediation) occur in the soils that surround the plants, while others occur after contaminants partition into plant tissues. Tossell said that the degradation processes that occur within plants and in the rhizosphere are not well understood, but that some of the enzymes that might be involved have been identified. For example, he said, cytochrome p-450, glutithione-S-transferase, and dehalogenase may play an important role in plant degradation pathways. Also, methane mono-oxygenase might be playing a role in the rhizosphere. In addition, he said, enzymes that cause reductive dechlorination play a role in converting TCE to ethane and carbon dioxide.

Tossell said that the Subgroup hopes to obtain a more thorough understanding of phytoremedial systems by creating a study protocol and finding sites that will implement it. The protocol will outline what laboratory tests and greenhouse tests need to be completed before field trials are conducted. It will also clearly indicate how to design field tests for various applications and will indicate which parameters should be monitored.

At this point, Tossell said, the Subgroup has three main goals: (1) complete a draft of the protocol, (2) identify sites that will implement the protocol, and (3) expand the Subgroup's membership. After data are generated at field sites, he said, the Subgroup will update the protocol and initiate a technology transfer communication effort.

THE ALTERNATIVE COVER ASSESSMENT PROGRAM SUBGROUP

Introductory Remarks
Steve Rock, EPA

Steve Rock, one of the co-chairs of the Alternative Cover Assessment Program (ACAP) Subgroup, provided background information on the Subgroup's history, goals, and activities, as well as an overview of the main concepts behind vegetative cover systems. He said that the Subgroup is evaluating whether vegetative covers can be a viable alternative to prescriptive RCRA-style landfill covers. To demonstrate that they can, he said, the Subgroup must show that alternative covers prevent (1) physical contact with underlying waste, (2) water from percolating downward toward ground-water tables, and (3) harmful gas production. In addition, he said, proof must be generated to show that vegetative covers perform at least as well as RCRA-style covers.

Rock used an analogy to describe the difference between an RCRA-style prescriptive cover and a vegetative cover. While the former is supposed to act like a raincoat, he said, the latter is designed to act more like a sponge. When precipitation falls on a landfill cover, Rock explained, it can either run off, sink in, evaporate, or transpire. RCRA-style covers are designed to minimize the amount of water that enters a cover by maximizing runoff. Vegetative covers do allow some water to enter; this water is absorbed by materials with high water-holding capacities, then extracted and transpired by plants. Thus, in theory, water that enters a vegetative cover should not percolate to ground water.

Rock said that there are two basic types of vegetative cover designs. Systems that are installed in arid or semi-arid climates, Rock said, typically use a mixture of local prairie grasses with shallow root systems (i.e., 70% of their roots are within the first 3 feet below ground surface). In areas where annual rainfalls are greater than 20 inches, deeper-rooted plants, such as hybrid poplars and willows, are used. Rock said that these trees, which have roots that reach 8 to 10 feet below ground surface, may be able to penetrate into waste layers.

Rock said that the Subgroup formed in December 1996, at a meeting in Fort Worth, Texas. Since that time, the Subgroup has met three times and has developed a detailed field study program. Rock cited the program's three main goals: (1) evaluate alternatives to prescriptive covers, (2) gather a data set that can be used to improve computer models and to develop regulatory guidance, and (3) help site managers/owners install, monitor, instrument, operate, and maintain alternative covers. Rock said that significant headway has been made in achieving these goals.

Rock said that the Subgroup has identified a monitoring scheme that can be used to assess cover performance. It recommends measuring the following water balance components:

Parameter	Monitoring Equipment Used
Precipitation	Rain gauge
Runoff	Collection weir, tipping bucket
Evapotranspiration	Meteorological station
Transpiration	Sap flow measurements
Infiltration	Lysimeter, soil moisture probe system

Rock said that the infiltration parameter, which represents how much water drains out of a cover, will be of great interest to regulators. Subgroup members spent much time talking about the best way to measure this parameter. It can be estimated indirectly, Rock said, but Subgroup members decided that it is necessary to use a direct measurement approach. Thus, the Subgroup recommends installing lysimeters underneath covers. These are designed to catch any water that escapes.

Once the Subgroup decided on a monitoring scheme, Rock said, it started working with site managers to install test pads (i.e., covers that have lysimeters under them) in the field. To date, he said, test pads have been installed at 5 sites, and they will be established at a total of 12 sites before the end of 2000. Rock said that the Subgroup's sites represent a wide variety of conditions. For example, they are located across a wide geographical range (California, Montana, Utah, Ohio, and Georgia) and have different climates. Even sites that are located relatively close together, he said, have different environmental conditions. For example, two of the Subgroup's sites are in Montana. While one receives most of its precipitation in the form of snow melt, the other receives most of it during dramatic thunderstorms.

Rock said that at least two test pads will be established at every site. One will have a RCRA-prescribed cover. The other will have an alternative cover. Through this side-by-side comparison, investigators will be able to determine if alternative covers perform as well as prescriptive caps. It would be difficult, if not impossible, to demonstrate equivalence otherwise, Rock said—very few studies have been performed to determine how well prescriptive covers prevent infiltration. Without this kind of data available, he said, there really is no numerical standard against which to compare alternative covers.

Rock said that the Subgroup will monitor the 12 Subgroup sites for a five-year period. During this time, Subgroup members will collect data from data loggers, post these data on a Web site, correlate drainage data with weather data, and produce annual summary reports. Rock said that data are currently only being shared among the Subgroup's core members. Eventually, however, these data will be made available to the public.

Before closing his talk, Rock provided an overview of the Subgroup's main players:

• Subgroup co-chairs. Rock said that the Subgroup is supposed to have two co-chairs, a government representative and an industry representative. Rock said that he is currently serving as the former, but that the latter position is vacant. He asked audience members to contact him if they are interesting in serving in this capacity.

• Site owners. Rock said that 12 sites will be participating in the Subgroup's program. Six of the sites are publicly owned. (These are mostly county landfills.) Four sites are privately owned. (Two of the owners are landfill operators and the other two are potentially responsible parties at hazardous waste sites.) One site is owned by DOD and one is owned by DOE. Rock said that the site owners have committed significant resources to participate in the Subgroup's program. For example, he said, owners pay about $80,000 to install test pads, and they commit significant time by serving as onsite field contacts. (In this capacity, they cooperate with Subgroup members by checking on field equipment as necessary.)

• Regional regulators. Rock said that the regulators who have jurisdiction over the 12 Subgroup sites are also considered part of the Subgroup's team. Subgroup members work with each regulator to identify project objectives up front. The criteria for a cover's performance, Rock said, differ between regions and states. For example, while some regulators may cite specific infiltration rates that must be achieved, others will say that alternative covers must simply perform as well as prescriptive covers to be considered successful. Rock said that it is important to define success criteria at the beginning of a project.

• Science Applications International Corporation (SAIC). Rock said that SAIC is the Subgroup's general contractor. He introduced two SAIC representatives: Mike Bolen and Art Roesler. Rock said that Bolen, the project's program manager, has played a key role in getting sites into the Subgroup's program and has processed several field work plans. Roesler, the project's field manager, has been present at all of the Subgroup's site installations and has developed equipment lists and spreadsheets that are used during test pad installation.

• Desert Research Institute (DRI). Rock said that DRI's Bill Albright has been involved with recruiting and advertising the Subgroup's program. In addition, Albright has performed much of the Subgroup's field work and is in charge of instrument calibration.

• University of Wisconsin. Rock said that the University of Wisconsin's Craig Benson has provided engineering input and has played a key role in developing lysimeter construction plans.

• Battelle Memorial Institute. Rock described Glendon Gee, a representative from Battelle Memorial Institute, as the father of alternative covers. He said that Gee's insight has been invaluable to the Subgroup.

After introducing these people, Rock asked Bolen, Roesler, Albright, Benson, and Gee to form a panel at the front of the room. Rock asked them to provide additional background information on the Subgroup's program and to solicit questions, comments, and suggestions from the audience.

Reporting Procedures

Bolen described the reports that are generated under the Subgroup's program. Before field activities are initiated at a site, he said, two documents are submitted to EPA for review:

• Site-specific design plan (SSD). Bolen said that the SSD, which serves as a work plan, describes the cover design that is to be tested in the field. It also provides information about regulatory issues that pertain to a particular site. Bolen said that site owners must design their own test covers; Subgroup members do not do this for them. After site owners (or their contractors) prepare the SSD, Subgroup members review the proposed design to make sure it is plausible.

• Quality Assurance Project Plan (QAPP). Bolen said that QAPPs are generated by the Subgroup. These documents describe the instruments and the quality assurance procedures that must be used to monitor test pads. Stringent requirements are outlined, he said, for instrument calibration and recordkeeping.

Sample SSDs and QAPPs will be posted on the RTDF Web site soon. After field activities are complete, Bolen said, summary construction reports are generated. These documents, typically about 300 to 400 pages long, explain how test sections were built and where instruments were placed.

Bolen said that the Subgroup's activities will be summarized in a series of annual reports. At the end of the entire project, short bulletins, a technology capsule (a 10-page pamphlet developed for regional offices), and two detailed technical reports will be released. Bolen said that one of these two technical reports (called a Technology Evaluation Report) will contain a very comprehensive explanation of the mechanics of the program and will contain all of the Subgroup's raw data. The other report (called an Innovative Technology Evaluation Report) will present a concise summary of how test covers can be applied full scale, and whether the economics of using vegetative covers are favorable.

The Subgroup's Monitoring System

Benson reiterated some points that Rock made earlier: (1) lysimeters can be used to measure any water that drains out the bottom of a test cover, and (2) lysimeters will be present at all of the Subgroup's test pads. Benson said that the Subgroup has created a series of documents that indicate how lysimeters should be constructed. He said that the lysimeter has been designed to be very durable and easy to construct. It can be installed, he said, without using special tools or specialty contractors. Also, Benson said, the lysimeter was designed to detect very small quantities of water without exerting significant influence on water-balance components.

Benson said that the lysimeter looks like a large bathtub. Its bottom, which is about 10 meters by 20 meters, is lined with a low density polyethylene geomembrane. A geocomposite drainage layer sits directly on top of this. Benson said that test covers are constructed over the lysimeters. These have top decks of about 20 meters by 30 meters and side slopes that are about 3 to 1 or 4 to 1. Water that falls onto the test covers, Rock said, is collected by different siphoning systems. For example, one system collects the portion that runs off, while another collects the portion that drains to the lysimeter. Gee described the collection system associated with the latter. He said that water that percolates to the lysimeter is routed to a tipping bucket, which tips if 10 milliliters of water accumulates in it. If the bucket is overwhelmed by too much water, Gee said, the water is captured in a siphon that has a capacity of about 90 liters. A pressure transducer is used to determine whether the siphon is working properly.

Albright said that data on a wide variety of parameters are being collected from the Subgroup's sites. For example, he said, data on precipitation (rain and snow), wind speed and direction, solar radiation, temperature, and humidity are being collected from onsite meteorological stations. In addition, measurement instruments have been attached to the lysimeters; these are being used to gather data on volumetric water content, soil moisture matric units, and soil temperature. (Instruments are established at three horizontal locations along the lysimeter. Each location is instrumented at several depths, the number of which differs from site to site. There are water content reflectometers at all three horizontal locations and heat dissipation units at the central location.) Gee said that the data that are being collected will be used to calculate evapotranspiration and potential evapotranspiration. Also, the data will be used to verify and validate existing predictive models.

Participants asked several questions about the monitoring system that is being used at the Subgroup sites. Questions revolved around the following topics:

• The sensitivity of drainage measurements. Flechas asked Subgroup members whether the lysimeter's water collection system is capable of detecting breakthroughs as small as one-tenth of a millimeter. Gee and Rock said that it definitely would. Gee said that the resolution on the tipping cup is about one-thousandth of a millimeter. The resolution on the siphon is about 0.5 millimeters.

• Drainage rates. Flechas asked whether drainage measurements have a time component. Gee said that they do, noting that drainage rates can be calculated because lysimeters record the time it takes for tipping buckets and siphons to fill.

• Has water drained out of the covers at any Subgroup sites yet? Ken Finkelstein asked whether drainage has been recorded at any of the Subgroup's field test sites yet. Albright said that it had, citing the Subgroup's Alabama site as an example. He said that water started draining out of this site's cap almost immediately. This is because the materials that were used in the cover were extremely wet. Albright said that trees have been established at this site; once they gain a foothold, they are expected to extract water from the wet materials. Albright said that it may take up to a full season to stop drainage at this site. At other Subgroup sites, Albright said, dry materials were used in the covers and drainage has not been a problem. For example, at one site, where a bentonite-filled sand was used in the cover, the tipping bucket has not tipped yet.

• Pre-wetting materials. One participant noted that a material's water-holding capacity must be exceeded before drainage becomes apparent. Thus, he said, it takes longer for water to drain from a dry material than from a wet one. Picking up on these thoughts, another participant asked if, at arid sites, it might take up to 10 to 20 years for a cover's materials to become wet enough for drainage to occur. If so, he asked, will the Subgroup's five-year study be adequate to test cover performance? These questions prompted other Subgroup members to suggest prewetting materials at the start of the field study program. Specifically, suggestions were made to prewet the following:
  
  

  —	The cover. One participant recommended irrigating the Subgroup sites before initiating data collection. Gee said that irrigation has been used at some sites, but that the decision was made not to do this at Subgroup sites.
  —	Geocomposite drainage layer. Finkelstein advised wetting the lysimeter's geocomposite drainage layer. Benson did not think this was necessary, noting that this material usually becomes fairly wet following the first few days after installation. Benson was not sure why this occurred, but wondered if condensation was involved. Benson said that other components of the lysimeter, such as the sump, are filled with water and monitored for leaks during installation. Thus, these parts are not dry either.

• Error bars on drainage measurements. One participant asked if the Subgroup has determined the error bars on drainage measurements. Rock said that it has not.

• The boundaries of the lysimeter and the cover. One participant noted that portions of the test cover do not lie directly over the lysimeter. Benson and Rock said that this was intentional. Having the test pads designed this way helps to minimizes boundary effects. Also, Rock said, with this design, investigators can perform excavations on portions of the cover without disturbing the lysimeter's structure. (Investigators perform excavations to determine how deep roots are and to evaluate settling and compaction rates.)

• Compaction (soil density) across sites. Flechas asked whether compaction is uniform at the test pads. Rock said that compaction rates vary from site to site, but are fairly uniform within a given site. (To ensure uniformity, Benson evaluates a number of samples during installation activities.) Most of the Subgroup's sites, Rock said, are using a compaction rate of about 85%. The soils should not be packed too tight, Rock said, because this could prevent root hairs from penetrating into them. At the same time, Benson said, the soil must be dense enough to support side slopes. (Wendi Goldsmith questioned whether plant root hairs can grow at the soil density percentage that Rock cited. She said that work performed by the U.S. Army Corps of Engineers suggests that plants experience difficulty growing in areas that have soil densities above 75%.)

• Changes in soil density over time. Finkelstein asked whether a cover's soil could become more compacted over time. If it can, he asked, did the Subgroup know how changes in soil density would impact water storage capacity? Gee said that it should not be assumed that soils will become more compacted over time at all sites. In some studies, he said, no additional compaction was observed six years after soils were laid down. In addition, he said, results obtained from civil surveys suggest that the height of soils can actually rise over time. This suggests that soils are loosening up at some sites, he said, possibly from freeze/thaw processes. Another participant said that he too knew of sites (e.g., a site that had full irrigation and farming machinery running over it repeatedly) where compaction did not increase over time. This participant did, however, question Gee's statement about freeze/thaw processes having the potential to loosen soils. He said that he read about a trail in Minnesota that was used to haul steel-wheeled wagons carrying up to 4,000 pound cargo loads. Even though the trail was abandoned about 100 years ago, the participant continued, freeze/thaw processes and other natural activities had not succeeded in loosening up the trail's soil.

• The lysimeter's geocomposite layer. One participant asked Benson why no drainage materials were placed between the lysimeter's geocomposite layer and geomembrane. Benson reminded the participant that the geocomposite layer is a drainage material. It was placed directly over the geomembrane instead of an earthen material because the former has a lower storage capacity. In addition, Benson said, the geocomposite material has another benefit: it cushions the geomembrane. (The geocomposite layer is thick, consisting of a geonet sandwiched between two geotextiles.) The participant asked whether stone had been considered as a drainage layer. Benson said that using stone would create a capillary break and that this would bias the system in a nonconservative fashion.

Collecting and Displaying Data

Albright said that data from the Subgroup's sites are collected by data loggers and sent directly to DRI. These data are then posted on a Web site in a near-real-time fashion. Albright hooked up to the Web site so that attendees could view the data and get an idea of the manipulations that can be performed on them. He said that data and site photographs can be viewed by clicking onto one of the Subgroup's sites. Daily data summaries can be obtained, he said, as well as time series graphs. The latter can be used, he said, to show how parameters change over time. Numerous parameters can be graphed on the same plot, he said; this allows investigators to look for correlations. Albright said that the Web site is still in development and that decisions are still being made about how to present data. For example, he said, some consideration is being given to averaging some of the data within a given site. Frank Beck (one of the attendees) advised against this, saying that it is more useful to present data for individual points.

Albright said that the Subgroup's data are posted on DRI's Web site (http://www.dri.edu), but that they can only be accessed by those who have passwords. Other useful information can be found on the public portions of the Web site, however, including information on how test sections have been designed. Rock said that introductory materials will probably also be posted in the near future.

Evaluating the Success of Alternative Covers

Participants talked at great length about the criteria that should be used to determine whether alternative covers have performed successfully. One meeting participant kicked off this discussion by saying that regulators have unrealistic expectations. He said that some recharge to ground water is inevitable and that regulators should accept the fact that it is impossible to design a landfill cover that will not have at least some drainage component. Rock thanked the participant for his comment, but said that the ACAP Subgroup believes that vegetative covers can be designed to satisfy the regulatory community's concerns.

Flechas said that he has heard ACAP Subgroup members state that 3 millimeters of breakthrough per year is an acceptable guideline to aim for. Flechas asked where this value came from. Albright said that EPA's Superfund Innovative Technology Evaluation program asked the Subgroup to identify a numerical standard for success. After reviewing available literature and performing some preliminary modeling, Albright explained, the Subgroup identified 3 millimeters per year as a general guideline. (A study by Stefan Melchior was the basis for choosing the number. This study measured drainage through a large-scale composite cover system in Hamburg, Germany, a city that receives about 800 millimeters of rain per year. Measurements were collected over eight years; results indicated that breakthrough was about 1 to 3 millimeters.) Albright and Rock assured Flechas that the 3-millimeter guideline is being used internally, and is not being advertised as an acceptable regulatory criterion. Rock said that he knows it is not yet possible to identify an overarching numerical criterion for acceptable drainage. Thus, site-specific success criteria have been established for the different Subgroup sites. The Subgroup will compare the efficacy of prescriptive and alternative covers by setting up side-by-side test pads.

Flechas said that he is concerned about having the 3-millimeter-per-year value cited, noting that values have a way of becoming institutionalized quickly. Thus, he asked the Subgroup to make it clear in all of their documents that success criteria are site-specific and must be established by a regulator. Rock said that the Subgroup will do so.

Flechas comments prompted Benson to ask: If 3 millimeters per year is too much, how much water drainage is acceptable from a regulatory point of view? Flechas said that it is not possible to answer that question at this time. Rock said that the data being generated by the Subgroup may help to identify a reasonable number.

Verifying, Validating, and Improving Predictive Models

Rock said that the Subgroup's program has three phases. As part of the first phase, he said, Subgroup members identified and evaluated models that can be used to predict cover performance. During the second phase, which is underway right now, field data are being collected on a variety of parameters. These data will be used, during the last phase of the project, to verify and validate existing models and to improve modeling capabilities.

Rock said that 13 models were identified and reviewed during Phase I activities. Four of them (HELP, EPIC, UNSAT-H, and HYDRUS-2D) were examined in great detail to determine how accurately they predicted water balance components at the Hanford site and the Coshocton, Ohio, site. This exercise was performed, Rock said, to identify the strengths and weakness of each of the models. The findings were summarized and submitted to EPA.

Of the four models that were evaluated, Rock said, HELP—designed, developed, and promoted by EPA—is the one most commonly used for predicting cover performance. He said that this model is very useful as a design tool, but does have some deficiencies. For example, it cannot predict water storage capacities accurately for cover designs that have multiple layers. These types of covers impose capillary breaks; HELP cannot account for these because it does not model upward flow or evaluate how water is stored in capillary barriers. Gee said that HELP also provides unrealistic estimates when field capacity and wilting point data are used to calculate available water capacity. In addition, Gee said, HELP has been shown to predict much greater drainage rates at arid sites than are actually observed in the field. Gee said that this may be because HELP, like most other existing models, is not good at estimating evapotranspiration.

Subgroup members did say that deficiencies were also identified with the other models that were tested, but they did not address these in detail. They did, however, note that all of the models are weak in the following:

• Estimating runoff. Benson said that most models cannot predict runoff accurately. While some yield overly conservative estimates, he said, the opposite is true for others. Some models are more accurate than others, however. (For example, HELP is better than UNSAT-H.)

• Adjusting for growing vegetation. Rock and Gee said that available models do not address seasonal variations or changes that result from vegetative growth. For example, the models do not account for the fact that leaf area index increases as vegetation becomes established on a cover.

Rock reiterated that one of the Subgroup's main goals is to improve modeling capabilities. He said that the Subgroup has not yet decided whether it will recommend making improvements to existing models or starting from scratch with brand new ones. He asked audience members for input on what should be done to create useful models for regulators and designers. (Rock said that he asked the same question at the Subgroup's February 1998 meeting. Several suggestions were offered; these are posted on the RTDF Web site as part of the summary report that was written for the meeting.)

Several attendees suggested augmenting HELP. They liked the idea of using this model as a basis because it is conservative, publicly available at no charge, and already popular. Gee and Rock agreed that this might be reasonable to do, although Rock cautioned that it may be difficult to create a revised HELP code that can predict cover performance in both arid and humid climates. Ken Finkelstein advised contacting HELP's original developer, Paul Schroeder, and asking for his assistance in revising the code. Attendees talked briefly about what could be done to augment HELP. One participant recommended incorporating components of forestry models that are used to calculate evapotranspiration. Rock said that the Subgroup does plan to review a variety of models to determine whether pieces can be borrowed and appended onto other models. Gee said that he would like to incorporate codes that include the Richards equation.

Rock asked attendees to comment on the costs of models, noting that some cost between $600 and $1,200. Specifically, Rock asked whether attendees thought models must be free or whether people would be willing to pay for them if they would vastly improve their landfill cover assessment programs. Very few attendees responded. Those who did thought the codes should be free, and said that this was one of the main reasons why they recommended using HELP as the basis for any new code. Albright pointed out that the FORTRAN computer code used in HYDRUS-2D is publicly available, even though it costs about $1,200 to purchase it with a Windows® interface. He said that the cost of developing a new interface would probably not be that great. Thus, if EPA would fund an interface development effort, this code could also be made available to the public at no charge.

Miscellaneous Topics

Several miscellaneous topics were discussed during question and answer sessions:

• The length of the Subgroup's study. One participant questioned whether the Subgroup's field program is being conducted over too short a time period. He asked whether five years is long enough to capture the extreme weather that regions are faced with. Rock acknowledged that sites will probably not be exposed to a full range of extreme weather over such a short period. He did say, however, that other investigators are performing studies to see how covers will perform under extreme stress. For example, he said, Bridget Scanlon is adding significant stress to test systems by adding irrigation. (Scanlon is conducting her studies separately from the Subgroup.)

• Taking advantage of lateral flow. One participant asked whether alternative covers can be designed to take advantage of lateral flow. Rock said that lateral flow is being captured from covers with drainage layers. Rock pointed out, however, that most of the covers being tested under the Subgroup's program are simple monoliths.

• Designing alternative covers. One participant pointed out that simple design features can be added to monolith vegetative covers to increase their likelihood of working. He asked how Subgroup members made decisions about whether to add these features. Rock reminded the participant that Subgroup members did not design the covers. Rather, all design decisions were made by site owners and their contractors. Eric Atchison (one of the audience members) noted that his company, Ecolotree, Inc., was one of the consultants that designed a cover for the Subgroup. He said that Ecolotree, Inc. used the HELP model to predict the cover's water-holding capacity; the results obtained were used to make decisions about the cover's depth and materials.

• Evaluating covers over unstable conditions. One participant asked whether the Subgroup plans to evaluate test pads at sites that generate gas. Rock said that the Subgroup's industrial partners are interested in such applications, but that doing so is currently beyond the Subgroup's scope. Before setting up test pads over these areas, he said, the Subgroup would need information on how gas diffuses through covers. Rock said that the lysimeters could be used to evaluate this in the future. (The lysimeters have been built with drains. After the Subgroup finishes its activities, a drain could be turned around and used as a gas injection point. A collection system could then be placed at the top of the cover to determine what gas gets through.)

• Bioreactors. Rock said that investigators plan to meet in Paducah, Kentucky, to discuss organic processes that generate water in waste materials.

Rock thanked everyone for attending the meeting, and for providing input and suggestions to the Phytoremediation Action Team's three Subgroups.

Attachment A: Final Attendee List
Annual Phytoremediation
Action Team Meeting
Omni Parker House Hotel
Boston, MA
May 3, 2000

Eric Aitchison Environmental Engineer Ecolotree, Inc. 505 East Washington Street Suite 300 Iowa City, IA 52240 319-358-9753 Fax: 319-358-9773 E-mail: ecolotreeE@aol.com * William Albright Research Hydrogeologist Water Resources Center Desert Research Institute University of Nevada 2215 Raggio Parkway Reno, NV 89512 775-673-7314 Fax: 775-673-7314 E-mail: billa@dri.edu Jon Baldwin Environmental Geologist Texaco P.O. Box 508 Beacon, NY 12508 914-838-7297 Fax: 914-838-7124 E-mail: baldwjj@texaco.com M. Katherine Banks Associate Professor School of Civil Engineering Purdue University 1284 Civil Engineering Building West Lafayette, IN 47906 765-496-3424 Fax: 765-496-1107 E-mail: kbanks@ecn.purdue.edu Felicia Barnett Office of Research and Development U.S. Environmental Protection Agency 61 Forsyth Street Atlanta, GA 30303 404-562-8659 Fax: 404-562-8628 E-mail: barnett.felicia@epa.gov Frank Beck Soil Scientist U.S. Environmental Protection Agency P.O. Box 1198 919 Kerr Research Drive Ada, OK 74821-1198 580-436-8554 Fax: 580-436-8703 E-mail: beck.frank@epa.gov * Craig Benson Associate Professor Geoengineering Program Civil and Environmental Engineering University of Wisconsin, Madison 1415 Engineering Drive Engineering Hall 2214 Madison, WI 53706 608-262-7242 Fax: 608-262-7242 E-mail: benson@engr.wisc.edu John Blake Assistant Manager Research Savannah River Institute USDA Forest Service P.O. Box 700 (760-15G) New Ellenton, SC 29809 803-725-8721 Fax: 803-725-1807 E-mail: j.blake@srs.gov Michael Blaylock Research Director Edenspace Systems Corporation 11720 Sunrise Valley Drive Reston, VA 20191 703-390-1100 Fax: 703-390-1180 E-mail: soilrx@aol.com Holger Boken Dipl. Ing Agr. (FH) Agronomy/Soil Protection/Soil Use Humboldt-University Berlin Dorfstr. 9 Berlin D-13051 Germany E-mail: holger.boeken@t-online.de * Michael Bolen Work Assignment Manager Science Applications International Corporation 411 Hackensack Avenue - 3rd Floor Hackensack, NJ 07601 201-498-7335 Fax: 201-498-7335 E-mail: bolenm@saic.com Martin Brand Senior Geologist Central Remedial Action Environmental Remediation Division New York State Department of Environmental Conservation 50 Wolf Road (7010) Albany, NY 12233-7010 518-457-5637 Fax: 518-457-7925 E-mail: mdbrand@gw.dec.state.ny.us Jim Brown Senior Bioremediation Specialist Lockheed Martin/REAC 1850 Wood Bridge Avenue Edison, NJ 08837 732-494-4060 Fax: 732-494-4021 * Henry Camp Arthur D. Little 20 Acorn Park Cambridge, MA 02140 617-498-5339 Fax: 617-498-7296 camp.henry@adlittle.com Judy Canova Project Manager Bureau of Land & Waste Management South Carolina Department of Health & Environmental Control 2600 Bull Street Columbia, SC 29201 803-896-4046 Fax: 803-896-4292 E-mail: jlcanova@aol.com Joan Colson U.S. Environmental Protection Agency 26 West Martin Luther King Drive Cincinnati, OH 45268 513-569-7501 Fax: 513-569-7585 E-mail: colson.joan@epa.gov Dennis Datin Professional Engineer Oklahoma Department of Environmental Quality 707 North Robinson P.O. Box 1677 Oklahoma City, OK 405-702-5125 Fax: 405-702-5101 E-mail: dennis.datin@deqmail.state.ok.us Paul Deutsch Principal Soil Scientist Geomatrix Consultants, Inc. 2444 Main Street - Suite 215 Fresno, CA 93721 559-264-2535 Fax: 559-264-7431 E-mail: pdeutsch@geomatrix.com Diane Easley Remedial Project Manager IANE Superfund Division U.S. Environmental Protection Agency 901 North 5th Street Kansas City, KS 66101 913-551-7797 Fax: 913-551-7063 E-mail: easley.diane@epa.gov Larry Erickson Professor of Chemical Engineering and Director, Hazardous Substance Research Center Kansas State University 105 Durland Hall Manhattan, KS 66506-5102 785-532-4313 Fax: 785-532-7372 E-mail: lerick@ksu.edu Linda Fiedler Environmental Engineer Technology Innovation Office U.S. Environmental Protection Agency Ariel Rios Building 5102G 1200 Pennsylvania Avenue, NW Washington, DC 20460 703-603-7194 Fax: 703-603-9135 E-mail: fiedler.linda@epa.gov * Felix Flechas Region 8 U.S. Environmental Protection Agency 999 18th Street - Suite 500 (8P-HW) Denver, CO 80202-2466 303-312-6014 E-mail: flechas.felix@epa.gov * Glendon Gee Staff Scientist Pacific Northwest Division Battelle Memorial Institute 3200 Q Avenue - ETB 1349 (MS K9-33) Richland, WA 99352 509-372-6096 Fax: 509-372-6096 E-mail: glendon.gee@pnl.gov * Stephen Geiger Senior Environmental Scientist R&D Services ThermoRetec 214 North Edgewood Street Arlington, VA 22201 703-522-0614 Fax: 703-522-0614 E-mail: sgeiger@thermoretec.com Jon Ginn Environmental Engineer Environmental Management Directorate 7274 Wardleigh Road Hill Air Force Base, UT 84056 801-775-6894 Fax: 801-777-4306 E-mail: jon.ginn@hill.af.mil David Glass President D. Glass Associates, Inc. 124 Bird Street Needham, MA 02492 617-726-5474 Fax: 617-726-1668 E-mail: dglassassc@aol.com Garry Goehring Manager, Environmental Engineering Alcoa Engineered Products 53 Pottsville Street Cressona, PA 17929 570-385-8802 Fax: 570-385-8609 E-mail: garry.goehring@alcoa.com Wendi Goldsmith Soil Scientist The Bioengineering Group, Inc. 18 Commercial Street Salem, MA 01970 978-740-0096 Fax: 978-740-0097 E-mail: wgoldsmith@bioengineering.com Milton Gordon Professor Department of Biochemistry University of Washington J391A Magnuson Health Sciences Center - Box 357350 Seattle, WA 98195 206-543-1769 Fax: 206-685-8279 E-mail: miltong@u.washington.edu Dibakar Goswami Co-Team Leader Phytoremediation Team ITRC/Washington State 1837 South Olson Street Kennewick, WA 99338 509-736-3015 Fax: 509-736-3030 E-mail: dgos461@ecy.wa.gov Kathy Greene Environmental Engineer Naval Facilities Engineering Service Center Installation Restoration Branch U.S. Navy 1100 23rd Avenue (Code 411) Port Hueneme, CA 93043 805-982-5284 Fax: 805-982-4304 E-mail: greeneka@nfesc.navy.mil Tammy Hall Hydrogeologist Toxics Cleanup Program Washington State Department of Ecology P.O. Box 4775 Olympia, WA 98504-7775 360-407-6247 Fax: 360-407-6305 E-mail: thal461@ecy.wa.gov Victor Hauser Principal Engineer Mitretek Systems 13526 George Road - Suite 200 San Antonio, TX 78230 210-479-0479 Fax: 210-479-0482 E-mail: vhauser@mitretek.org Jane Hendricks Unit Coordinator Hazardous Waste Management Branch Environmental Protection Division Georgia Department of Natural Resources 205 Butler Street, SE - Suite 1462 Atlanta, GA 30334 404-657-8600 Fax: 404-657-0807 E-mail: jane_hendricks@mail.dnr.state.ga.us James Higgins Manager, Ecological Engineering Environmental Engineering Division Jacques Whitford Environment, Ltd. 1200 Denison Street Markham, ON L3R 8G6 416-495-8614 Fax: 905-479-9326 E-mail: jhiggins@jacqueswhitford.com Rob Hoey Geologist Bureau of Remediation and Waste Management Maine Department of Environmental Protection State House Station 17 Augusta, ME 04333 207-287-7650 Fax: 207-287-7826 E-mail: rob.hoey@state.me.us Pat Hughes Senior Hydrogeologist Groundwater Technology Team Chevron Research and Technology Company P.O. Box 1627 100 Chevron Way - Room 10-3650 Richmond, VA 94802 510-292-5952 Fax: 510-242-1380 E-mail: joph@chevron.com Jim Jordahl CH2M Hill, Inc. 825 Northeast Multnomah Suite 1300 Portland, OR 97232 503-235-5022 Fax: 503-736-2022 E-mail: jjordahl@ch2m.com Dylan Keenan Environmental Engineer Western Remediation Branch Environmental Remediation Division New York State Department of Environmental Conservation 50 Wolf Road Albany, NY 12233-7010 518-457-5636 Fax: 518-457-3972 E-mail: dtkeenan@gw.dec.state.ny.us John Kornuc Naval Facilities Engineering Service Center Anteon Corporation U.S. Navy 1100 23rd Avenue (Code 411) Port Hueneme, CA 93043 805-982-1615 Fax: 805-982-4304 E-mail: kornucjj@nfesc.navy.mil * Peter Kulakow Department of Agronomy Kansas State University 2004 Throckmorton Plant Sciences Center Manhattan, KS 66506-5501 785-532-7239 Fax: 785-532-7239 E-mail: kulakow@ksu.edu Norm Kulujian Engineer U.S. Environmental Protection Agency 1650 Arch Street Philadelphia, PA 19103-2029 215-814-3130 Fax: 215-814-3015 E-mail: kulujian.norm@epa.gov

Mitch Lasat Office of Solid Waste & Emergency Response U.S. Environmental Protection Agency 401 M Street, SW (5102G) Washington, DC 20460 703-603-1234 E-mail: lasat.mitch@epa.gov Stacy Lewis Hutchinson Research Environmental Engineer National Exposure Research Laboratory Ecosystems Research Division U.S. Environmental Protection Agency 960 College Station Road Athens, GA 30605-2720 706-355-8267 Fax: 706-355-8202 E-mail: lewis.stacy@epa.gov Lena Ma Associate Professor Soil & Water Science Department University of Florida Gainesville, FL 32611-0290 352-392-9063 Fax: 352-392-3902 E-mail: lqma@ufl.edu Kelly Madalinski Environmental Engineer U.S. Environmental Protection Agency 1200 Pennsylvania Avenue, NW (5102G) Washington, DC 20460 703-603-9901 Fax: 703-603-9135 E-mail: madalinksi.kelly@epa.gov Karen Maiurano Geologist Division of Environmental Remediation New York State Department of Environmental Conservation 50 Wolf Road Albany, NY 12233-7010 518-457-5636 E-mail: ksmaiura@gw.dec.state.ny.us Stephen Mangion U.S. Environmental Protection Agency 1 Congress Street - Suite 1100 (HBS) Boston, MA 02114-2023 617-918-1452 E-mail: mangion.steve@epa.gov Steve McCutcheon Research Environmental Engineer National Exposure Research Laboratory Ecosystems Research Division U.S. Environmental Protection Agency 960 College Station Road Athens, GA 30605 706-355-8235 Fax: 706-355-8202 E-mail: mccutcheon.steven@epa.gov Andrea McLaughlin Office of Emergency & Remedial Response U.S. Environmental Protection Agency 1200 Pennsylvania Avenue, NW (5202G) Washington, DC 20460 703-603-8793 Fax: 703-603-9133 E-mail: mclaughlin.andrea@epa.gov Victor Medina Assistant Professor Department of Civil & Environmental Engineering Washington State University Tri Cities Branch Campus 100 Sprout Road Richland, WA 99352-1643 509-372-7376 Fax: 509-372-7471 E-mail: vmedina@tricity.wsu.edu * Robert Mueller Research Scientist New Jersey Department of Environmental Protection/ITRC 401 East State Street - P.O. Box 409 Trenton, NJ 08625 609-984-3910 Fax: 609-292-7340 E-mail: bmueller@dep.state.nj.us M. Cristina Negri Soil Scientist/Environmental Engineer Energy Systems Division Argonne National Laboratory 9700 S. Cass Avenue Argonne, IL 60439 630-252-9662 Fax: 630-252-9281 E-mail: negri@anl.gov Lee Newman Research Assistant Professor College of Forest Resources University of Washington Box 352100 Seattle, WA 98195 206-616-2388 Fax: 206-543-3254 E-mail: newmanla@u.washington.edu Valentine Nzengung Department of Geology University of Georgia Athens, GA 30602 706-542-2699 Fax: 706-542-2425 E-mail: vnzengun@arches.uga.edu Paul Olson Post-Doctoral Fellow Biology Department Bioresources & Chemical Engineering Colorado State University A/Z Building (E414) Fort Collins, CO 80523 970-491-3320 Fax: 970-491-0649 E-mail: peolson@lamar.colostate.edu Douglas Outlaw Professional Engineer Hazardous Waste Regulation Florida Department of Environmental Protection 2600 Blair Stone Road (MS 4560) Tallahassee, FL 32399-2400 850-921-9259 Fax: 850-921-8018 E-mail: douglas.outlaw@dep.state.fl.us Dave Palochko Environmental Operations Leader Environment, Health & Safety Department Owens Corning One Owens Corning Parkway Toledo, OH 43659 419-248-8878 Fax: 419-325-4878 E-mail: david.palochko@owenscorning.com Kalpesh Patel Environmental Engineer Corrective Action Branch Bureau of Land Illinois Environmental Protection Agency 1021 North Grand Avenue, E (33) P.O. Box 19276 Springfield, IL 62794-9276 217-524-3862 Fax: 217-524-3291 E-mail: epa4426@epa.state.il.us Ravi Patraju Environmental Engineer Bureau of Discharge Prevention New Jersey Department of Environmental Protection P.O. Box 424 Trenton, NJ 08625-0424 609-292-1690 Fax: 609-633-7031 Robert Peale Senior Geologist Bureau of Remediaion & Waste Management Technical Services Division Maine Department of Environmental Protection State House Station 17 Augusta, ME 04333-0017 207-287-7679 Fax: 207-287-7826 E-mail: rob.n.peale@state.me.us Elizabeth Pilon-Smits Assistant Professor Biology Department Colorado State University Anatomy/Zoology Building Fort Collins, CO 80523 970-491-4991 Fax: 970-491-0649 E-mail: epsmits@lamar.colostate.edu Marcia Quigley Bioenvironmental Engineer Center for Environmental Excellence U.S. Air Force 3207 North Road Brooks Air Force Base, TX 78235 210-536-4366 Fax: 210-536-4330 E-mail: marcia.quigley@hqafcee.brooks.af.mil Mike Reynolds Research Physical Scientist Cold Regions Research & Engineering Laboratory U.S. Army Corps of Engineers 72 Lyme Road Hanover, NH 03755 603-646-4394 Fax: 603-646-4230 E-mail: reynolds@crrel.usace.army.mil * Steve Rock Environmental Engineer U.S. Environmental Protection Agency 26 West Martin Luther King Drive Cincinnati, OH 45268 513-569-7149 Fax: 513-569-7879 E-mail: rock.steven@epa.gov Charles Sagoe Towa Kagaku Company, Ltd. 6-5 Funairi Naku-ku Hiroshima, Japan 730-0841 81-82-292-3111 E-mail: sagoe@mail.towakagaku.co.jp * Art Roesler Science Applications International Corporation 411 Hackensack Avenue - 3rd Floor Hackensack, NJ 07601 201-498-4335 Fax: 201-498-4335 * Phil Sayre U.S. Environmental Protection Agency Ariel Rios Building 7403 1200 Pennsylvania Avenue, NW Washington, DC 20460 202-260-9570 E-mail: sayre.phil@epa.gov Bridget Scanlon Senior Research Scientist Bureau of Economic Geology University of Texas at Austin University Station - Box X Austin, TX 78713 512-471-8242 Fax: 512-471-0140 E-mail: bridget.scanlon@beg.utexas.edu Paul Shoemaker Program Assistant Office of Environmental Health Boston Public Health Commission 1010 Massachusetts Avenue 2nd Floor Boston, MA 02118f 617-534-5966 Fax: 617-534-2372 E-mail: paul_shoemaker@bphc.org Ken Skahn Environmental Engineer Superfund Program U.S. Environmental Protection Agency Ariel Rios Building (5202G) 1200 Pennsylvania Avenue, NW Washington, DC 20460 703-603-8801 Fax: 703-603-9133 E-mail: skahn.ken@epa.gov Bill Smith Project Manager Cummings/Riter Consultants 339 Haymaker Road - Suite 201 Monroeville, PA 15146 412-373-5240 Fax: 412-373-5242 E-mail: wsmith@cummingsriter.com Frances Stanley Associate Consultant TechLaw, Inc. 160 North Washington Street Suite 400 Boston, MA 02114 617-720-0320 Fax: 617-720-0321 E-mail: fstanley@techlawinc.com Jami Striegel Roberts, Schornick & Associates, Inc. 2488 East 81st Street - Suite 610 Tulsa, OK 74137 918-496-0059 Fax: 918-496-0132 E-mail: jstriegel@benham.com Phillip Thompson Assistant Professor Department of Civil & Environmental Engineering Seattle University 900 Broadway - Room 524 Seattle, WA 98122 206-296-5521 Fax: 206-296-2173 E-mail: thompson@seattleu.edu * Robert Tossell Senior Consultant Toronto Branch GeoSyntec Consultants 160 Research Lane - Suite 206 Guelph, Ontario N1G 5B2 CANADA 519-822-2230 Fax: 519-822-2230 E-mail: btossell@geosyntec.com * David Tsao Research Engineer Hydrocarbon & Environmental Management BP Amoco 150 West Warrenville Road (H-7) Naperville, IL 60563 630-420-4321 Fax: 630-420-4321 E-mail: tsaodt@bp.com Mike van Bavel President Dynamax, Inc. 10808 Fallstone - #350 Houston, TX 77099 281-564-5100 Fax: 281-564-5200 E-mail: mvb@dynamax.com William Jody Waugh Principal Scientist Roy F. Weston 2597 B 3/4 Road Building 938, Room 242 Grand Junction, CO 81503 970-248-6431 E-mail: jody.waugh@doegjpo.com Robin Wilcox EHS Specialist GE Power Systems One River Road Building 273 - Room 3080 Schenectady, NY 12208 518-385-4358 Fax: 518-385-0627 E-mail: robin.wilcox@ps.ge.com Richard Willey Hydrologist Office of Site Remediation & Restoration U.S. Environmental Protection Agency One Congress Street Suite 1100 (HBS) Boston, MA 02114-2023 617-918-1266 Fax: 617-918-1291 E-mail: willey.dick@epa.gov Nelson Lee Wolfe Senior Research Chemist National Exposure Research Laboratory Ecosystems Research Division U.S. Environmental Protection Agency 960 College Station Road Athens, GA 30605-2700 706-355-8207 Fax: 706-355-8202 E-mail: wolfe.lee@epa.gov Donald York Manager, Environmental Site Remediation Union Pacific Railroad 327 Spencer Street West Chicago, IL 60185 630-876-2795 Fax: 630-876-4644 E-mail: dryork@notes.up.comes.up.com RTDF/Logistical and Technical Support Provided by: Christine Hartnett Conference Manager/ Technical Writer Eastern Research Group, Inc. 5608 Parkcrest Drive - Suite 100 Austin, TX 78731-4947 512-407-1829 Fax: 512-419-0089 E-mail: chartnet@erg.com Carolyn Perroni Senior Project Manager Environmental Management Support, Inc. 8601 Georgia Avenue - Suite 500 Silver Spring, MD 20910 301-589-5318 Fax: 301-589-8487 E-mail: carolyn.perroni@emsus.com Laurie Stamatatos Conference Assistant Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02421-3136 781-674-7320 Fax: 781-674-2906 E-mail: lstamata@erg.com

* Speaker

Attachment B: Phytoremediation Diagrams

The phytoremdiation diagrams are available as a 27.7KB PDF file. To download Adobe Acrobat Reader to view the diagrams, go to http://www.adobe.com/products/acrobat/readstep.html.