PHYTOREMEDIATION OF ORGANICS ACTION
TEAM
ALTERNATIVE COVER SUBGROUP
CONFERENCE CALL
3:30 p.m. - 5:00 p.m.
March 30, 1998
On Monday, March 30, 1998, members of the Phytoremediation of Organics Action Team, Alternative Cover Subgroup, met via a conference call. The following members participated:
Tom Wong, Union Carbide Corporation (Subgroup Co-chair)
Steven Rock, U.S. Environmental Protection Agency (EPA) (Subgroup Co-chair)
William Albright, Desert Research Institute (DRI)
Mary Beck, EPA Region III
Craig Benson, University of Wisconsin
Paula Estornell, EPA
John Fletcher, University of Oklahoma
Ray Hinchman, Argonne National Laboratory
Lucinda Jackson, Chevron Corporation
Kelly Madalinski, EPA
Bruce Pivetz, ManTech Environmental Research Services Corporation
Paul Schroeder, U.S. Army Engineer and Waterways Experiment Station
Steve Wall, EPA Region IX
Glenn Wilson, DRI
Also present was Christine Hartnett of Eastern Research Group, Inc. (ERG).
SUMMARY OF THE ALTERNATIVE COVERS WORKSHOP IN LAS VEGAS, NEVADA
William Albright summarized the proceedings of the Alternative Covers Workshop that was held on February 17 and 18 in Las Vegas, Nevada. The workshop brought together researchers, regulators, and site owners (e.g., Department of Defense [DOD], Department of Energy [DOE], and Bureau of Land Management [BLM]). State regulators from most of the states west of the Mississippi were invited, and about 10 attended. The workshop was held to solicit feedback about the Alternative Covers Assessment Program (ACAP). The ACAP proposes to fill existing data gaps by collecting data from a network of facilities throughout the country. The workshop took place over 2 days and included the following presentations and activities:
Albright said that the workshop was very productive and that the ACAP approach seems valid in that it will help solve design and permitting issues.
Tom Wong asked whether any clear direction emerged during the panel discussion. Wilson
responded by
saying that good points had been brought forth, and that the modelers were open to suggestions
from the
crowd, but that no clear future direction had been established. For the most part, workshop
participants
agreed that most of the needs are met by one model or another. In off-the-record conversations,
Albright
learned that some people would like a model like MODFLOW developed. MODFLOW is a
model for ground-water flow that was developed by the U.S. Geological Survey.
VISIT TO COSHOCTON, OHIO
During the Subgroup's last conference call, representatives from Geraghty & Miller, Inc., told the group about a 30- to 40-year data set that has been collected at the U.S. Department of Agriculture's (USDA's) facility in Coshocton, Ohio. John Fletcher said that he followed this lead and visited the facility about a month ago. While there, he toured the facility, looked through data sets, and talked to the facility's operators. Fletcher provided the conference call participants with a summary of his findings.
As a plant physiologist, Fletcher was "tremendously" impressed with the facility and the historical data that has been gathered on site. The facility was built in the 1930s and is still operational. Data have been collected from the site nearly every year since operations commenced. The facility has been set up to evaluate crop plants with lysimeters. Fletcher said that he was particularly intrigued by data collected from a group of four lysimeters, one of which is a 65-ton weighing lysimeter used exclusively for pasture-type crops.
Water relationships have been evaluated at Coshocton, and Fletcher described the results as "remarkable." Originally, alfalfa and brome grass were planted at the site. As the alfalfa died out and the grass took over, the precipitation entering the system started equaling the evaporation. (Coshocton receives about 30 to 40 inches of rain a year.) For a block of 3 years, the system attained or nearly attained a water balance (i.e., no through flow). During the first year, the amount of through flow equaled zero. For the subsequent 2 years, the through flow measured about 1 to 1.5 inches. Fletcher noted that these results are particularly impressive since the area was mowed during the midsummer monthsa time when evapotranspiration (ET) activities should be at their peak.
Through discussions with Malone [Note: spelling of name not confirmed], a facility representative, Fletcher learned that a number of USDA facilities (e.g., a site in Fresno) throughout the country may have valuable data. Fletcher suggested that the RTDF Subgroup consider performing a project at Coshocton. He noted that using Coshocton as a test facility would help answer questions that are being asked by people in Illinois, Ohio, and Indiana about how covers will perform during winter.
Fletcher said that the Coshocton facility may be receptive to new projects. Wilson, who is also familiar with the site, said that Coshocton has one of the most extensive data sets available and that the data has only been partially analyzed. Wilson said that the Coshocton facility is investing significant effort in analyzing previously collected data, but he also agreed that facility staff would likely be receptive to taking on new projects as well. He noted that the facility's funding is shrinking and that staff members are worried about losing their laboratory. They are eager to become involved in projects that tie into funding sources other than USDA. Wilson suggested, therefore, that Coshocton would be receptive to teaming up with EPA. (Wilson noted that this site is interesting because it has a certain type of earthworm that significantly effects soil drainage.)
Fletcher said that Malone is receptive to the idea of installing grasses at the site and
managing them in a
fashion that will help address the RTDF Subgroup's questions and needs. At this point, Malone
does not
want to install trees because he thinks they will disturb the texture and composition of the soil.
Fletcher said
that this shouldn't be a problem. He suggested that the Subgroup should not limit themselves to
trees.
RTDF NEEDS
Installation of Monitoring Devices and a Discussion on the Subgroup's Focus
Rock noted that the Subgroup needs to identify which data must be collected to satisfy the regulatory community's questions about alternative covers. He suggested that monitoring requirements will be somewhat site-specific, but stressed that there should be as much consistency as possible. He proposed splitting the country into regions and making sure that monitoring activities are consistent within regions.
Rock asked participants for feedback on what kinds of monitoring devices and data should be used and collected at test sites. Because different monitoring systems provide answers to different questions, Rock's question sparked a lengthy debate about the Subgroup's focus. Wong noted that the Subgroup was originally formed to evaluate whether alternative covers could achieve:
Whether the Subgroup still wants to focus its attention on both issues is a matter of debate. Conference call participants agreed that it is imperative for the Subgroup to evaluate the containment component. There was less consensus on the importance of going forth with monitoring efforts that evaluate the treatment component.
Rock stated that the group should focus on containment. To Rock, all that is important is that the alternative cap reduces risk to an acceptable level.
The participants talked about how containment and treatment impact overall risk at a given site. Wong suggested thinking about a scenario where a phytocover is placed on 50 feet of waste. Participants noted that the treatment component would only be effective on the first 10 to 20 feet, because roots have difficulty penetrating further. While reducing the source of contaminants is helpful, the overall risk at the hypothetical site would only be reduced sufficiently if the cover could contain (i.e., prevent contaminant migration from) the bottom 30 to 40 feet of wastes.
Craig Benson agreed that containment and treatment are both important, but he said that the latter could not be addressed within the next 5 years. From a practical standpoint, tackling both issues simultaneously is too broad and unrealistic. Benson said that the key to gaining regulatory approval is the ability to prove containment. If the Subgroup focuses on containment, Benson said, it will have a better chance of producing something that can be used by the engineering and design community. Benson stressed that the ACAP is focused on applied research and guidance development rather than fundamental science.
Schroeder agreed that the focus needs to be on containment. He asked the participants whether any models are able to predict how effectively plants degrade contaminants. Fletcher and Rock told him that no such models are currently available. Without predictive tests, Schroeder argued, regulators will not be comfortable using a technology. Schroeder said that regulators will not put much faith in the treatment component of the technology unless they have predictive models that are based on greenhouse and laboratory testing. Fletcher noted that it would be difficult to predict performance based on greenhouse studies. He said that tests that involve microbial populations have little meaning unless they are performed in the field.
Wilson said that, as far as the ACAP is concerned, the focus has to remain on containment. He added, however, that he had always thought the issue of treatment would be handled by the RTDF Subgroup. Wilson suggested that an effort to investigate the treatment component of alternative caps would complement the ACAP's work.
Paula Estornell asked the group what type of monitoring is needed to measure the treatment capabilities of a cover. She said that it is important to keep the focus on containment, but that it would be great to collect data on the cap's treatment potential if at all possible. If the requirements are not too extensive, collecting as much positive information as possible will bring the most "bang for the buck," Estornell said.
Albright agreed that it would be ideal to collect data related to the cap's treatment potential. But he also identified a couple of logistical problems that could arise if the Subgroup wants to pursue this angle under the ACAP:
Both Albright and Estornell asked Fletcher to comment on what monitoring would be required to better understand the treatment component of alternative covers. Fletcher responded that monitoring would have to be site-specific. He said that there would be some benefit in identifying sites that already have pump systems in place to track contaminant migration. Other than that, a wide variety of rhizosphere studies could be conducted to see how the concentration of contaminants changes over time and what microflora populations are present. Albright said that it would be relatively easy for him to keep an eye out for the type of sites that Fletcher is looking for when he initiates Phase I of the ACAP. (Phase I is scheduled to begin in early April and involves a review of a variety of sites.)
Rock reminded the participants that the Subgroup is a "capping group" and that the two other RTDF Phytoremediation of Organics Subgroups are investing efforts to learn more about the mechanisms of the treatment component of phytoremediation. He noted that sites have been set up to evaluate whether trees can degrade trichloroethylene in ground water. Also, several field sites are analyzing phytoremediation of contaminated soil. Fletcher agreed that these studies are important, but he said that he would like to perform some studies using mixed waste.
Rock said that the Subgroup's primary goal needs to be measuring the caps' efficiency. He said that the first set of monitoring devices installed by the Subgroup should evaluate whether covers act as barriers. Evaluating contaminant degradation is a worthy secondary goal, Rock said, and he is open to suggestions about ways to do this.
Rock has compiled a list of monitoring activities that he would like to see performed at every test facility. He agreed to distribute the list to Subgroup participants. (The list is included as Attachment A.) He asked the participants to look at the list and offer feedback. Ideally, he said, the Subgroup may want to consider making a tiered list, which separates data collection activities into three categories: 1) those that definitely need to be performed, 2) those that should be performed if the program has additional money available, and 3) those that should be performed if someone else is willing to pay for it.
Plant Selection
The talk about the Subgroup's focus spurred a discussion about plant selection. Participants debated whether plants should be selected based on their ET properties or their biochemistry. The biochemical properties of a plant are important in determining how:
Cap Design
Two types of sites may be incorporated into the ACAP: 1) sites with several small demonstration plots, and 2) sites with full-scale caps. In some cases, full-scale caps have already been installed. In other cases, site owners and regulators are in the process of identifying an appropriate design. Rock stressed that site owners will be expected to pay for their covers and will be responsible for the design of the cap. He did note, however, that owners will be encouraged to get input from the RTDF Subgroup and the ACAP team.
Benson said that it is dangerous to separate design people from monitoring people. He suggested that many consulting companies are not knowledgeable enough to produce a good alternative cover. He cited a site where, in his opinion, the alternative cover was practically designed to fail. Benson stressed that site owners will not be pleased if they sink money into an alternative cap, only to have it fail.
Albright assured Benson that the ACAP team plans to evaluate designs and to provide input before accepting sites into the program. In March, Albright received a call from a consulting company that is designing a cover for a California facility. The consulting company wanted to participate in the ACAP. Albright explained that the company would have to pay a little money so that the ACAP team could analyze 1) the facility design to make sure that it can produce the quality of data that the ACAP needs, and 2) the cover design.
Albright stated that there is a real benefit to monitoring installed covers. He reminded the
participants that
the Subgroup can learn from "failures" as well as "successes." Albright's comment sparked a
brief
discussion on defining terms such as "failure," "success," and "leaking." Rock recommended
reading Brent
Nixon's paper for definitions. The paper can be found in Waste Management and
Research.
RTDF STRUCTURE/COMMITMENTS
It has been determined that the team needs to compile a list of sites that are committed to participating in the program. Rock noted, however, that site owners can't be expected to commit themselves unless they fully understand what is expected of them.
DRI has pulled together a proposal that outlines what is needed from site owners. The document defines data needs and explains how data must be collected. Albright said that it would be a good idea to distribute the document to the Subgroup, to get input, and then to distribute the document to site owners. Benson noted that the document should "spec" out the whole monitoring system.
Albright and Wilson reported that several site owners are ready to come on board. Albright
has been
getting calls from people saying "We've got sites, we've got money, where is your program?"
Benson said
that he has a client who wants to build a cap in the summer. Rock said that he knows of a site in
Cincinnati
that could be a candidate for some monitoring. Wilson added that Glendon Gee has identified
some candidates as well.
ACTION ITEMS
Wong identified the following as Action Items:
DATE FOR NEXT CALL
The next conference call is scheduled for May 4, 1998, between 3:00 and 5:00 p.m. (EST).
The call will focus on the modified DRI proposal.
ATTACHMENT A
ACAP         DRAFT Monitoring System
The evaluation criteria of the performance of a landfill or containment system should be its ability to hold its contents. In the case of hazardous or municipal waste landfills, the goal of the system is to prevent leakage to groundwater or surface water, and to prevent hazardous gas emissions.
A monitoring system should directly measure the efficacy of the containment system. Since confining the waste within container boundaries is the goal, the first monitoring should be established at those boundaries. For a shallow aquifer this might include upgradient and downgradient water-quality sampling, and periodic air sampling. For a deep aquifer this might require retrofitting the site with shallow pan lysimeters, or time domain reflectometry (TDR).
Second, the monitoring system should measure the inputs into the projection of the
containment
performance. Alternative covers rely on evapo-transpiration, so the e-t rates should be calculated
from on-site weather data: precipitation, solar input, wind, temp, humidity. Vegetation coverage
will have to be
estimated by inspection. These secondary measurements will confirm the information from the
primary
measurements, and provide inputs for predictive models for future projects.
Parameter | Equipment | Units |
---|---|---|
In Ground | ||
Water Sampling | well | contaminant concentration |
Water Level | tensiometer in well | feet above sea level |
soil moisture | TDR | |
pan lysimeter | installed under cap | cm of water |
Above Ground - On Site Weather Station | ||
precipitation | rain gauge | inches (cm) |
solar input | solar gain meter | |
wind speed | wind gauge | |
temperature max & duration | recording thermometer | o C ( oF) |
humidity | humidistat | |
Periodic On Site Sampling and Inspection | ||
Gas wells, periodic gas sampling, FTIR, or other | ||
Vegetation coverage inspection |
Most of the devices listed above can and should be connected to data recording equipment (dataloggers). Those datalogging devices can be hooked up to modem so the information can be collected from a remote location from one or several collection centers.