Meeting held March 26, 1999 in Miami, Florida
Disposal of CCA-Treated Wood: Existing and Alternative Management Options
Agenda for TAG Meeting
-Results from Year 2
-TCLP/SPLP, U.Florida Townsend/Messick
-Solvent Extraction, U.Miami Solo-Gabriele/Calitu
-Sorting Study, work with stains and ASOMA Equipment Solo-Gabriele/Kormienko
-Dicussion of Year 2 Results
5. Plans for next year (year 3) Solo-Gabriele/Townsend
-Phase I: Alternative Chemicals
-Phase II: Disposal-End Management
-Distribution of Questionnaire's Developed for Year 3 Research Solo-Gabriele/Kormienko /Gary
Attendees in Miami:
Vandin Calitu, Graduate Student, University of Miami, Coral Gables, FL
Lee Casey, Chief Environ. Compliance Division, Metro-Dade County Dept. of Solid Waste, Miami, FL
Kenneth Cogan, Technical Representative, Hickson Corporation, Conley, GA
Keith Drescher, Environmental Specialist, Florida Power & Light, West Palm Beach, FL
Kelvin Gary, Undergraduate Student, University of Miami, Coral Gables, FL
Bill Krumbholz, Environ. Manager, Dept. of Environ. Protection - Solid Waste Div., Ft.Myers, FL
Lisa Martin, Engineer II, Florida Department of Environmental Protection, Tallahassee, FL
Brian Messick, Graduate Student, University of Florida, Gainesville, FL
Helena Solo-Gabriele, Assistant Professor, University of Miami, Coral Gables, FL
Ram Tewari, Project Manager, Broward County Comm. Solid Waste Operations Div., Ft. Lauderdale, FL
Timothy Townsend, Assistant
Professor, University of Florida, Gainesville, FL
Attendees in Gainesville via Teleconference:
Bill Gay, Wood Preserving Group Manager, Langdale Forest Products Co., Valdosta, GA
Maria Hall, Research Associate, Florida Center for Solid & Haz. Waste Mgt., Gainesville, FL
John Schert, Executive Director,
Florida Center for Solid & Haz. Waste Mgt., Gainesville, FL
The meeting began at 10:20 am and ended at 12:15 noon
Dr. Helena Solo-Gabriele welcomed all TAG members and invited guests to the meeting.
Individuals present in Miami and at the remote site in Gainesville introduced themselves by stating their name and affiliation.
3. Results from Year 2
Dr. Helena Solo-Gabriele described the format for the morning's presentations which were to occur in two parts. First results from last year's study (year 2) would be presented followed by a description of the plans for next year. Dr. Solo-Gabriele then described the objectives of the year 2 study which included an ash leaching study (including TCLP and SPLP tests and solvent extraction experiments) and a sorting study (including chemical stains and x-ray fluorescence). She then described the sample preparation procedure for the ash leaching studies which included the collection of wood controls and samples from C&D recycling facilities. Controls were then shredded and samples were ashed using an industrial furnace owned by Florida Power and Light.
TCLP and SPLP Tests
Dr. Townsend described the significance of TCLP and SPLP procedures including the relevance of such procedures in designating a waste as hazardous and in determining the potential impacts of the waste upon receiving waters. Brian Messick described the analytical details of the TCLP, SPLP, and total recoverable metals tests conducted on the ash samples. The method included size separation, pH measurements, extractions with leaching solutions, and metals analyses. Results showed that the pH of the leaching solutions were generally higher for SPLP than for TCLP except for the 2.50 pcf sample. As a result, TCLP solutions are generally more aggressive with TCLP leachate concentrations for copper generally higher than the SPLP concentrations. A notable exception was observed for the 2.50 pcf sample. For arsenic small differences were noted between TCLP and SPLP results. Chromium extracts were not as expected, especially notable was the below detection limit value for the 0.60 pcf ash sample. All samples exceeded TCLP limits for arsenic, except for the C&D#1, C&D#2, and untreated wood samples. TCLP exceedances for chromium were observed for the 0.25 pcf and C&D#1samples. All samples, except for untreated wood, exceeded at least one of the groundwater guidance concentrations for chromium, copper, and arsenic. Brian Messick also described an additional study investigating concentration changes over short time intervals throughout the TCLP and SPLP tests. Different variations in metal concentrations were observed with time. Dr. Townsend made a few closing remarks including that the 5% mixture of treated wood with untreated wood is considered to be borderline for failure of TCLP tests. Wood ash, even if it contains minimal amounts of CCA, would not likely pass criteria for land application. The abrupt changes in metal concentrations during the TCLP tests during the first few minutes were surprising. Results suggest that perhaps a shorter test (<18 hours) can be utilized for TCLP and SPLP analysis. Chromium behavior during the leaching studies merits more exploration.
Solvent Extraction Study
Vandin Calitu presented the results of the solvent extraction study. The extraction was conducted in two parts. The first part consisted of an extraction with a particular solvent. Each extraction was followed by a total recoverable metals extraction in sequence. Analytical methods were described. Total metals provided on the plots were referenced to a total metals concentration, as determined by computation. Dr. Solo-Gabriele added that the research team has initiated two additional analytical methods for directly measuring the total metal concentrations in the original sample. These methods include energy dispersive x-ray fluorescence and neutron activation. Vandin Calitu then described the results of the extraction emphasizing the finding that the total mass of metals removed (mg/L) increased with initial sample retention value. Strong acids were found to be the most powerful solvents removing up to 47% of the copper, 23% of the chromium, and 13% of the arsenic. The highest percent removals were observed for samples containing the least CCA (except for weathered wood in the case of arsenic). It was also noted that measureable amounts of chromium were removed with weak solvents. Dr. Solo-Gabriele mentioned that given the low percent removals, the solvents tested would likely not be a cost effective means for extracting metals for recycling purposes. Although the results were not promising from a metals recycling point-of-view, they are valuable in evaluating the environmental impacts of treated wood ash. Especially notable is the mobility of chromium by the action of weak solvents. Recommendations were provided for further research.
Question: John Schert asked why the TCLP and SPLP of the samples were the same for arsenic but different for copper. Tim Townsend responded by stating that the solubility of arsenic is not as sensitive to pH as is the solubility of copper.
Question: Keith Drescher asked if there were biological processes available for removing CCA from wood. Helena Solo-Gabriele responded by stating that there is currently a significant amount of work in this area evaluating the ability of fungii to dissolve the metals into water, thereby treating the wood.
Question: Ram Tewari asked why the weathered wood samples showed higher percent removals than the wood controls. Helena Solo-Gabriele suggested that perhaps the weathering process affects the manner in which the metals are bonded to the wood. She also mentioned that the utility pole utilized for the experiments was produced 20 years ago, when other formulations for CCA were more popular, thereby resulting in different leaching characteristics.
Question: Ken Cogan asked if the original retention level was experimentally determined for the CCA-treated wood. Helena Solo-Gabriele responded that it was not; however, Bill Gay, through earlier correspondence, had agreed to perform the analysis for the research team. Ken Cogan asked Bill Gay how the analyses were to be performed. Bill Gay mentioned that many replicates would be conducted utilizing ASOMA equipment. Bill Gay also plans to send the samples to an inspection agency. Ken Cogan mentioned that he would also conduct the analysis. It was agreed that Dr. Solo-Gabriele would send samples of unburned wood to Bill Gay. Bill Gay will then provide the residual dust from the analysis to Helena Solo-Gabriele. Helena Solo-Gabriele will then send this material to Ken Cogan for confirmatory analysis.
Chemical Stain Experiments
Dr. Solo-Gabriele mentioned that the sorting work was conducted by a graduate student, Monika Kormienko, who could not make it to the meeting due to her participation at another conference. Dr. Solo-Gabriele described the three stains that were tested including chrome azurol, rubeanic acid, and PAN indicator. The formulation for chrome azurol was modified to improve the rate at which the color change occurred. With the new formulation, which is alcohol based, the reaction is immediate. The original formulation for rubeanic acid required two separate stains; the new formulation requires only one. Distinct color changes were observed for all three chemical stains. This was observed for whole pieces of wood, shredded wood samples prepared in the laboratory, and for most field samples collected from C&D recycling facilities. The chemical chosen for use is dependent upon personal preferences. Dr. Solo-Gabriele prefers the chrome azurol due to its deep blue color since it is not usually observed for soiled wood waste. The stains were found suitable for most but not all recycled wood waste. Recycled wood waste which contained a lot of soil or fibrous material did not stain well. The stains can be used to sort small quantities of treated wood from untreated wood and for screening fuel quality. Plans for next year include the publication of results from the sorting study and informing C&D recyclers of the technologies available for sorting treated from untreated wood.
X-ray Fluorescence Technology
Dr. Solo-Gabriele mentioned that three studies were performed to evaluate the suitability of x-ray fluorescence technology for sorting CCA-treated wood from the remaining wood waste stream. The primary effort consisted of a two day visit to ASOMA headquarters located in Austin, Texas. The theory of x-ray fluorescence was briefly described. Some background information was provided for ASOMA instruments including the characteristics of the different x-ray analyzers they manufacture. The primary purpose of the work with x-ray technology was to determine whether x-ray analyzers were feasible for sorting treated from untreated wood using an on-line automated system. Experiments conducted were designed to determine the best metal for analysis, the detection limit for the technology, minimum analysis time, and the maximum spacing between the sensor and wood for proper analysis. Conclusions from these experiments were that the best indicator metal was arsenic; the minimum detection limit for the instrument is a 3 to 5% mixture of CCA-treated wood; the minimum count time was 2 seconds; however, the true minimum is likely shorter for an on-line system since time will not be needed for the sensor shutter to open and close. Detection of whole pieces of wood (0.25 pcf) is possible at a 1 inch distance. This distance is adequate whether or not a plastic shield is used to protect the sensor. The advantages of x-ray fluorescence include no sample preparation, no alteration or contamination of the wood being analyzed, low maintenance, and no waste generation. The primary disadvantage is cost; an on-line system will cost between $20,000 to $100,000. Currently the research team is investigating options for funding a demonstration unit.
Question: John Schert asked whether recycling facilities actively sort treated wood out of the waste stream, especially given that TCLP limits may be exceeded in the ash residue when CCA is present in the fuel at low concentrations. Tim Townsend responded by stating that only obvious pieces, such as utility poles, are sorted out. Bill Krumbholz added that the pressure to sort was not observed in the field. Ram mentioned that Atlas Waste is having a problem selling its wood waste to Okeelanta. There appears to be some QA/QC initiatives by the cogeneration plant.
Question: John Schert asked whether the research team was successful in testing the ash from the Okeelanta facility. Helena Solo-Gabriele mentioned that representatives from Okeelanta were contacted; however, they did not want to provide samples. John Schert added that it may be more accurate to measure the amount of CCA treated wood in a sample by analyzing the ash rather than the unburned material.
Question: Lee Casey asked about the depth over which the ASOMA x-ray analyzer could detect CCA. His question was focused on determining the maximum depth of wood on a conveyor system. Helena Solo-Gabriele mentioned that the ASOMA equipment analyzes the surface of the wood, therefore only one piece of wood could be analyzed at a time by the x-ray analyzer.
Question: Ken Cogan asked if x-ray analyzers from other companies were evaluated. Helena Solo-Gabriele mentioned that Oxford, the primary competitor to ASOMA, produces an analyzer that uses an x-ray tube rather than a radioactive source to produce the x-rays needed for analysis. However, the instrument Oxford currently has available requires considerable sample preprocessing. Oxford analyzers do not have a remote probe similar to that of the ASOMA analyzer. The x-ray tube has its advantages; however the Oxford analyzer will have to undergo considerable modifications in order to minimize sample pre-processing.
Question: Ram Tewari mentioned that he is aware of one C&D facility in Broward that produces mulch from wood waste. The spec sheet from this facility does not specify that CCA-treated wood is to be removed prior to the production of the mulch. He also mentioned that there is still a problem with the CCA-treated wood once it is sorted-out. What can be done with the material that is rejected? Tim Townsend mentioned that mulch is a big business in Florida and that he has noted that CCA separation is limited at C&D facilities. Ken Cogan added that if separation is to occur it must occur prior to mulching. Ram Tewari then mentioned that home owners have asked him about disposal of wood decking and fencing; however, there is currently no solid answers concerning what can be done with the material
Question: Tim Townsend asked about the reporting practices for ash analyses. Bill Krumbholz mentioned that up until a couple of years ago, cogeneration plants were exempt from the ash rule which required reporting. Tim Townsend asked about how to track the increase in CCA through the disposal sector. Bill Krumbholz mentioned that testing of the ash can be required by the landfill accepting the ash waste. Keith Drescher mentioned that such testing may not happen very often. Ram Tewari mentioned that Broward County accepted 10% of the ash from the Okeelanta facility. Broward County at that time required that an independent laboratory conduct the extractions. Ram Tewari also mentioned that Palm Beach County Solid Waste Authority also accepted a considerable amount of the ash from Okeelanta, and they too should have records concerning ash quality.
Question: Ram Tewari asked about how CCA-treated wood is disposed in other states. Helena Solo-Gabriele mentioned that most other states have not tracked the disposal of CCA-treated wood. One state, Minnesota, is considering a ban of CCA-treated wood. Ken Cogan added that disposal was not the issue motivating the ban in Minnesota. It was motivated by concerns over the presence of chromium(VI) versus chromium(III).
Question: Ram Tewari asked about pit burners. He mentioned that the ash from such burners was generally land applied. Helena Solo-Gabriele mentioned that Dr. Shieh of the Florida Institute of Technology has conducted a study on such incineration systems. He found many such facilities throughout the state. Tim Townsend added that Dr. Shieh's findings support that CCA-treated wood can be found in the ash. Usually, air emissions are the primary factors evaluated when permitting these facilities.
4. Presentation of Research Results to Date
Dr. Solo-Gabriele presented the plans for next year's research titled, "Chemical Alternatives and Improved Disposal-End Practices for CCA-Treated Wood." Next year's study consists of two phases: Phase I, Alternative Chemicals, and Phase II, Disposal-End Management. Alternative chemicals considered for next year's study are waterborne preservatives that contain no arsenic and which have been used commercially to some extent. Alternative chemicals initially considered include: alkyl ammonium compound, ammoniacal copper quat, borates, copper azole, ammoniacal copper citrate, and copper dimethydithiocarbamate. Evaluation of these chemicals will include feedback from the chemical manufacturers, wood treaters, and from large end-users of CCA-treated wood. Work on disposal-end management will focus on field demonstrations of sorting technologies, an evaluation of available pyrolysis systems, and developing a sourcebook for the wood disposal sector. A final report along with a draft copy of the sourcebook will be available by March 2000. The practical benefits of the research were listed.
Two questionnaires were distributed to the TAG for their evaluation. One questionnaire will be sent to wood treaters inquiring about alternative chemicals and another will be sent to C&D facilities to inform them of the chemical stains.
Dr. Solo-Gabriele asked the TAG members to provide either written or verbal comments on the final technical report within the next two weeks.
The next TAG meeting has
been scheduled for July 12, 1999 in West Palm Beach, Florida.