SUMMARY OF THE REMEDIATION TECHNOLOGIES DEVELOPMENT FORUM
IN-PLACE INACTIVATION AND NATURAL ECOLOGICAL
RESTORATION TECHNOLOGIES SOIL-METALS
ACTION TEAM MEETING
Las Vegas, Nevada
January 2122, 1998
WELCOME AND INTRODUCTIONS
Dr. Jim Ryan, U.S. Environmental Protection Agency (EPA)
Dr. Bill Berti, DuPont Central Research and Development
Dr. Jim Ryan and Dr. Bill Berti, meeting co-chairs, welcomed participants and reviewed the agenda for the two-day In-Place Inactivation and Natural Ecological Restoration Technologies (IINERT) Soil-Metals Action Team meeting. The goal of the meeting was to continue efforts initiated at the May 1997 IINERT Action Team meeting, including the following:
Dr. Berti noted that one major objective of this meeting was for the group to discuss the draft IINERT research document, distributed to participants prior to the meeting. The document includes some background information and an outline of the major research efforts the IINERT Soil-Metals Action Team plans to undertake. Dr. Berti emphasized that much of the meeting would be devoted to expanding on and detailing the overall research plan.
Workshop participants introduced themselves. The group communicated their common interest in developing, refining, and using in situ techniques as a cost-effective alternative to digging and hauling metal-contaminated soils off site. Several participants noted that much progress has been made to date. The group was anxious to identify additional research/experiments that are needed to help more clearly demonstrate the effectiveness of available in situ techniques.
The meeting agenda and a list of meeting participants are included as attachments to this meeting summary.
JOPLIN FIELD RESEARCH SITE
Mr. Mark Doolan, EPA
Dr. Sally Brown, U.S. Department of Agriculture - Agricultural Research Service (USDA-ARS)
Mark Doolan and Sally Brown provided an update on the ongoing research at this residential site that was contaminated as a result of lead smelting and mining. The approximate one-acre site (roughly a city block) is contaminated with 400-5,000 parts per million (ppm) lead. Mr. Doolan summarized EPA's activities at the site. EPA's goal is to treat soils in place; despite initial resistance to in-place treatment, the community is slowly warming up to the idea. The contamination was plotted and the distribution of lead contamination was studied to evaluate how each plot would be treated. EPA applied agricultural-grade phosphoric acid (1 percent) via three different application methods (i.e., rototilling, pressure injection, and surface aeration). After application and curing, EPA studied the distribution of phosphate through the soil to evaluate the efficiency of the different methods. Of the three methods used to apply the soil amendment, rototilling was shown to be the most effective.
In vitro results showed a 78 percent reduction in bioaccessibility in bench-treated soils and a nearly 90 percent reduction in field tests (likely due to a drastic reduction in pH). In vivo tests (on swine) were run using both bench- and field-treated soils. Blood, liver, kidney, and bone lead measurements revealed an approximate 35 percent reduction in bioavailability for both field and bench amendments. Mr. Doolan noted that while the reduction is not bad, it is not as high as they had hoped. EPA will be dosing one more sample to the swine which is considered to represent optimum conditions (a bench sample treated over a year ago, maintained at a constant temperature, with several wetting and drying cycles).
A short discussion followed on whether blood or bone lead is a better indicator of bioavailability. Although it was agreed that blood lead is variable over time and dependent on feeding patterns, the group decided that measuring blood lead (the index used to evaluate lead poisoning in children) is the most practical approach.
Mr. Doolan noted that samples were also studied (using scanning electron microprobes) for chloropyromorphite content. Treated soils matched control standards, suggesting chloropyromorphite had been formed in the treated soils. EPA also has speciation data for these soils; all information will be presented in a final comprehensive report.
Researchers (Ruby and Drexler) are developing and testing an in vitro method which is using soil samples run through a swine model. Samples include a variety of soil types (with different minerology/speciation). The correlation between in vitro and in vivo results is being evaluated and the method is being refined. EPA is looking very closely at this method and hopes to validate the method by early summer 1998 (by comparing its results to the in vivo/swine data). Validating an in vitro method would have great cost benefits. In vivo studies, especially those using swine, can be very expensive (approximately $25,000).
Dr. Brown presented a summary of recent USDA research including rat, soil (in vitro), and plant (grass)
studies. USDA is using the same field plots as EPA. She explained that plant and soil samples were
collected from the field site to evaluate the effectiveness of 10 different treatments. Investigators also
looked at the effects of the various treatments on plant growth. Plant lead results showed great variation.
Dr. Brown also presented the in vitro results. Based on available in vitro and plant data, she asked the
group for suggestions on the best treatment/amendment to use for her upcoming rat dosing study. She
noted that USDA has performed one rat dosing study using the same samples dosed to swine; the results
were comparable to the swine study, but discouraging in terms of percent reduction in bioavailability. She
also noted that reductions vary across methods (rat, soil, grass) and across treatments, which is a little
discouraging.
INTERNATIONAL LEAD ZINC RESEARCH ORGANIZATION LEAD RESEARCH
PROGRAM
Dr. Andrew Green, International Lead Zinc Research Organization (ILZRO)
Andrew Green presented an overview of ILZRO's ongoing and proposed research activities. He briefly described the organization's primary research areas, suggesting the possibility of combining some of ILZRO's and the IINERT Soil-Metals Action Team's efforts:
This three-part project involves developing/refining pharmacokinetic models to study correlations between environmental lead concentrations and blood lead levels; performing Monte Carlo-type simulations to predict exposures, and validating models to be used as predictive tools. Results of these efforts are due out in the spring of 1998.
This project includes four substasks including (1) a critical review of past remediated sites worldwide (successes and failures; published and unpublished), (2) review of field sampling results (soil chemistry) at these sites, (3) information transfer (working on the development of a web page, including a bulletin board to announce meetings, papers, etc.), and (4) a reciprocity project through which the best U.S. and European techniques are being exchanged.
Assuming continued funding, this program will continue to look at the bioavailability of copper, lead, and possibly zinc in animals (worms) and plants. ILZRO is collecting approximately 40 to 50 samples worldwide to complete chemistry and develop a predictive model.
Dr. Green also announced the upcoming 16th International World Congress on Soil Science to be held in
Montpellier, France, in August 1998.
SOLUBILITY BIOAVAILABILITY RESEARCH CONSORTIUM (SBRC)
Dr. Bill Berti, DuPont Central Research and Development
Dr. Berti presented the results of recent research efforts on arsenic and lead bioaccessibility/ bioavail-ability studies, comparing new and old in vitro methods and comparing in vivo results with the new in vitro method results. A good correlation was observed between the old and new in vitro methods when looking at lead. Dr. Berti cautioned that the test results represent only a limited number of untreated soil samples, with limited quantities. He questioned whether the same correlation would be seen in treated soils. With arsenic, in vivo to in vitro correlations were not as good. The group recognized that one test is not likely to satisfy requirements for different metals.
A good correlation was also seen when comparing in vitro to in vivo (swine) results. Arsenic bioaccessibility and bioavailability correlations were not as good.
Related Discussions
Rufus Chaney briefly described an ongoing collaborative effort between EPA Region III and the U.S. Agency for International Development in which interaction of metals at a zinc/lead smelter site in Poland are being studied. The results of hay analysis suggest that the presence of metals together can influence the bioavailability of one or the other. Studies such as this one should help us better understand the risk to crops being grown on sites being remediated.
The group briefly discussed the concept of "meta-analysis" (i.e., pooling bioavailability data sets from as many sources as possible to increase overall data pool). While meta-analysis is possible, the concept is controversial because of the possible lack of homogeneity across data sets (e.g., different methodologies, etc.).
Dr. Ryan discussed the importance of understanding the chemical form/mineralogy of lead in different pH
systems. Studies are ongoing to evaluate the chemistry of different minerals. These studies are critical to
better understanding the differences observed in in vitro versus in vivo tests. To optimize in vitro systems,
scientists need to understand the chemical form and where the critical transformation processes are. The
group recognized the progress in this area since first discussions in 1995. The goal now is to validate an in
vitro method that will enable movement towards the group's ultimate goal of a field-demonstrated
remediation technology that also protects ecosystems.
DISCUSSION OF OTHER NON-PROPRIETARY INFORMATION
Dr. Jeff Newton, IWT Company
Dr. Nick Basta, Oklahoma State University
Dr. Newton provided an overview of his research efforts related to the remediation of organic-contaminated soils, much of which has also involved studying the behavior of metals in treated soils. He described the concepts of his "georemediation" techniques, which involve applying a combination of phosphorous, glass, and silicates. Dr. Newton indicated that the stable "ordered" mineral forms created after treatment render them less bioavailable, noting that the bioavailability of metals is dependent on the organic content of the soil. The technique is relatively inexpensive and grass can be grown following treatment. The results of Dr. Newton's research will be presented in a paper being released by the North Atlantic Treaty Organization in the spring of 1998; while the paper does not address lead in soils specifically, the concepts presented are applicable to the Action Team's work.
Dr. Nick Basta described his research activities in quantifying the bioavailability of arsenic in contaminated
soils by in vitro gastrointestinal (GI) methods. He discussed the advantages of in vitro over in vivo
(swine) methods. In vitro techniques provide an inexpensive and quick way of determining "rough" or
"estimated" bioavailability. Dr. Basta's GI in vitro procedures mimic gastric and intestinal phases,
particularly with respect to pH. With the samples studied to date, a good correlation has been observed
between in vivo and in vitro methods.
RESEARCH DOCUMENT & DISCUSSION
Dr. Berti and Dr. Ryan reviewed the status of the evolving IINERT research document, which defines
IINERT's goals and will serve as the Action Team's work plan. The document describes IINERT's
research plan, including identification of sites, collection of soil samples, standard analysis of samples, and
areas for research. The group reviewed the draft outline and identified areas requiring additional work
(e.g., ecological toxicity). Dr. Berti presented a draft bioavailability matrix (a.k.a. "soil bioavailability
scorecard") of existing in vivo studies and suggested that this be included as an appendix to the research
document. The matrix includes study title, collaborators/institution, source of funding, test system
characteristics, compliance/ethical issues, group size, and cost per substrate. Dr. Berti encouraged the
group to provide additional input to the matrix. Other attachments to the research document will include
papers describing activities at field research sites (Joplin, Bunker Hill, and Palmerton), soil characterization
methods, and the results of the soil/site survey.
SOIL/SITE SURVEY RESULTS
Dr. Berti provided an update on the soil/site survey recently distributed to everyone on the IINERT Soil-Metals Action Team mailing list. The purpose of the survey is to help the Action Team identify possible field demonstration sites and to collect sufficient quantities and types of soils for research purposes. To date, 16 responses to the survey have been received. A simple spreadsheet has been developed that summarizes these responses, most of which represent mining/smelting sites. The information presented in the spreadsheet which includes site name, EPA region, site size, lead concentration, other metals present, site use, presence of floodplain, bioavailability information, and site contact. Dr. Berti commented that supplemental information on site size and detected lead concentrations needs to be requested. As evidenced by some of the responses, some minor shortcomings of the survey need to be resolved.
The group discussed key issues associated with selecting field demonstration sites. The group agreed to try
to identify 100 potential sites within the next 1 to 2 months. The ultimate goal is to select at least six sites
from each of the five possible lead source areas (i.e., mining/smelting, industrial/waste sites, orchards,
urban soils, and firing ranges). A protocol needs to be developed specifying how the final sites will be
selected, what sampling should be performed, and who will collect samples. The group identified issues
that might limit site inclusion: accessibility, confidentiality, and timing (e.g., depending where a Superfund
site is in the record-of-decision process, a field demonstration could slow down the process and be viewed
as nonadvantageous).
BUNKER HILL STUDY
Dr. Sally Brown, USDA-ARS
Dr. Charles Henry, University of Washington
Dr. Brown and Dr. Henry presented a status report of the remedial activities at the Bunker Hill site. The site, one of the largest metal process/smelter facilities, created contamination that poisoned nearby elementary school children in the early 1970s. The site consists of 1,200 to 1,500 acres of highly sloping/eroding lands. Past attempts to grow grass and pine seedlings have not been very successful. Soils contain 2,000 ppm zinc and have a pH of 3. Dr. Brown discussed the primary obstacles encountered when trying to remediate this type of environment, including:
Dr. Brown described the biosolids/ash/residual amendment applied to site soils. The addition of this type of mix is advantageous for the following reasons:
The mixture is highly adhesive so it adheres well to the slopes. Dr. Brown described the replicated series of field plots (tailings) that they treated. Lead was detected at concentrations up to 10,000 ppm, with a pH of 6 to 7. Application of the amendment has resulted in successful revegetation/growth in the tailings area. The group discussed the observed tomato growth (as a result of using biosolids) and possible lead uptake. Other studies have shown limited uptake by tomatoes in lead-contaminated areas, but Dr. Brown agreed to analyze tomatoes next season in response to continued public concern and risk assessment needs reported by the group.
Dr. Henry discussed the third phase of the Bunker Hill ecological restoration program. The objectives of this large-scale demonstration and long-term ecological research program are as follows:
This collaborative effort, involving the Northwest Biosolids Management Association and researchers (USDA, University of Washington, University of Idaho), will serve as an instrument for long-term research. Potential funding sources include EPA Region X, EPA Headquarters, and private organizations. Dr. Henry briefly described the steep-slope application technology being developed and tested, noting that the technique has good coverage (can scan a distance of up to 2,000 feet and fling 150 feet on both sides) and revolutionizes the cost for application. Depending on funding, it is anticipated that the Phase III efforts of development and application of technology will be initiated in 1998. Ideally, the study will evaluate the following:
The group discussed the prospects of the long-term effectiveness of such treatments (what happens when
plants penetrate surface compost?). Dr. Brown and Dr. Henry are optimistic that a persistent vegetative
cover can be maintained because this amendment introduces legumes and adds organic matter and nutrients
providing an inoculum and substrate for nutrients. Furthermore, mineral soil below the amendment has
been shown to be metabolically active and diverse (the amendment brings the soil pH up to make it calcarious). They emphasized that it is important to consider the kind of material being remediated to
determine the specific blend of the amendment.
SUBGROUP BREAKOUTS
The three research subgroups met independently over the course of the two-day meeting. The three research areas and the "hypothesis" for each subgroup are presented below.
Field Application (In-Place Inactivation)
Engineered addition of materials to lead-containing soils will induce the formation of less-hazardous lead
forms, providing a practical approach to in-place inactivation.
Bioaccessibility/bioavailability
Surrogate relationships can be identified/confirmed among lead availability to humans, pigs, rats, and
glassware extraction.
Chemical Form (Solid Reactions/Components)
Good correlation exists between soil components and soil-lead hazard.
The subgroups were charged with reviewing the draft research document and modifying it as necessary to clearly define future research efforts, including timelines, costs, and possible resources. The groups were asked to prioritize what needs to be done, starting where they left off after the May 1997 meeting.
[One participant suggested that additional effort should be made to involve the Department of Defense
(DOD) in IINERT's efforts because of the nature of their sites.]
REPORTS FROM SUBGROUPS
Each of the subgroups presented a summary of their discussions on research needs and next steps.
Field Application (leader Sally Brown)
The group concurred with the objectives of field research studies as stated in the draft research document. That is, the primary objectives of the field application component of the IINERT Soil-Metals Action Team's work are:
In selecting a site, the following criteria need to be considered:
The choice of treatment is dependent on the laboratory screening results (fine-tune treatments based on extensive treatability [laboratory in vitro, in vivo]). In addition, the decision to choose one of the five most promising treatments (to use on all sites) is based on:
To test application efficacy in the field, the group proposes factorial experiments, which include use of the technologies and optimizing techniques listed below.
Sampling and analysis in the field would consist of the following:
Scheme
Suggestions for laboratory screening include:
The group's recommendations for field demonstration and public education include:
Bioaccessibility/Bioavailability (leader Bill Berti)
The group's discussions are summarized below.
| 1) | Perform in vitro and in vivo lead analyses on 13 arsenic samples. | |
| Who: Timeline: Cost: |
Nick Basta 1 to 3 months <$10,000 |
|
| 2) | Analyze IINERT soil samples (30 sites); select subset for animal dosing. |
|
| 3) | Review relevancy of using swine as surrogate for children. |
|
| Timeline: Cost: |
1 year $500,000 (untreated soil samples) $1M (treated samples) |
|
| [The group as a whole discussed whether monkey studies should be pursued and discussed
the overall acceptability of the swine model. The group agreed to consult the Science
Advisory Board report on the swine model for further insight, including information on
low-dose information. In addition, USDA's upcoming rat study should provide useful
information on comparability of results using a rodent species.] |
||
| 4) | Build database of lead bioavailability of pure lead minerals. |
|
| 5) | Acquire data for lead ranging from 400 to 2,000 ppm. |
|
| 6) | Evaluate Ecotoxicity Issues |
|
National Biological Survey?) |
||
Chemical Form (Solid Reactions/Components) (leader Jim Ryan)
The group outlined the primary analyses to be conducted on the samples collected as part of IINERT's research program.
| 1) | Solid-phase characterization |
| 2) | Sample particle-size separation (sand, silt, clay) |
| 3) | In vivo bioavailability |
| The group questioned whether all samples should be fed to swine/rats. Consensus was that in vitro
is adequate for soils from different sites. |
|
| 4) | Excellent correlation exists between mineral forms and bioavailability. In mixed-metals systems, it is therefore necessary to understand what is affecting solubility. |
The group as a whole discussed the logistics of the sampling effort (a timeline and dollar amounts need to be set for the effort).
The Action Team is still working on site identification and where to take samples, including considering issues related to confidentiality. Concern was raised regarding possible limitations that might result if some site owners are not willing to disclose full site information. The group agreed that for the data to be useful, the Action Team needs to know as much about the site as possible.
Protocols need to be developed for handling and shipping samples; EPA's Office of Radiation and Indoor
Air may have applicable protocols (e.g., sampling, distribution to laboratories, chain of custody, etc.)
already in place that could possibly be adapted to the Action Team's soil collection effort.
DECISION DIAGRAM AND DISCUSSIONS
Soils/sites selection criteria
Experimentation
Time line for completion
Resources
The final session of the meeting was a group discussion on IINERT's draft research proposal. The purpose of the discussions was to solicit input from the group that will enable the completion of the draft. Dr. Berti charged the group with working together to identify more sites and to work through the required steps for the collection, preparation, characterization, and storage of the soil samples. The highlights of these discussions are presented below.
[New guidance calls for sieving all soil samples to 250 microns, but the group agreed that, regardless, all fractions need to be considered for treatment.]
Action Team members were requested to send additional comments and/or corrections on the draft research
document to Dr. Berti; he invited the group to rewrite sections as needed.
RTDF IINERT SOIL-METALS ACTION TEAM WORKSHOP
Las Vegas Hilton
Las Vegas, Nevada
January 21-22, 1998
AGENDA
WEDNESDAY, JANUARY 21, 1998
| 7:00AM | Continental Breakfast |
| 8:00AM | Welcome and Introduction Drs. Jim Ryan, U.S. EPA and Bill Berti, DuPont |
| 8:30AM | Joplin Field Research Site Mark Doolan, U.S. EPA and Sally Brown, USDA-ARS |
| International Lead Zinc Research Organization (ILZRO) Lead Research Program Andrew Green, ILZRO |
|
| 10:00AM | BREAK |
| 10:30AM | Solubility Bioavailability Research Consortium (SBRC) Bill Berti, DuPont Discussion of Other Non-Proprietary Information |
| 12:00PM | LUNCH - on your own |
| 1:30PM | Research Document and Discussion |
| 2:30PM | Soil/Site Survey Results |
| 3:00PM | BREAK |
| 3:30PM | Subgroup Breakouts Bioavailability/Bioaccessibility Subgroup Solid Reactions/Components Subgroup In-Place Inactivation: Reduction to Practice Subgroup |
|
THURSDAY, JANUARY 22, 1998 |
|
| 7:00AM | Continental Breakfast |
| 8:00AM | Reconvene |
| 8:15AM | Reports from Subgroups |
| 9:30AM | BREAK |
| 10:00AM | Decision Diagram and Discussions Soils/Sites Selection Criteria Experimentation |
| 12:00PM | LUNCH - on your own |
| 1:30PM | Decision Diagram and Discussions Time Line for Completion Resources |
| 5:00PM | ADJOURN |
RTDF IINERT Soil-Metals
Action Team Meeting
Las Vegas Hilton
Las Vegas, NV
January 21-22, 1998
Final Attendee List
|
Nick Basta Bill Berti Sally Brown Rufus Chaney Mark Doolan Andrew Green Charles Henry Steve Hutchinson Gus Lo |
Carl Ma Technology Innovation Office U.S. Environmental Protection Agency 401 M Street, SW Washington, DC 20460 703-603-9903 Fax: 703-603-9135 E-mail: ma.carl@epamail.epa.gov Michelle McGregor Jeffrey Newton Gary Pierzynski James Ryan Lane Tickanen RTDF logistical and technical support provided by: Naida Gavrelis Susan Brager Murphy Laurie Stamatatos |