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Comparison of Environmental Impacts of Wood Treated with Chromated Copper Arsenate (CCA)and Three Different Arsenic-Free Preservatives

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Title:
Comparison of Environmental Impacts of Wood Treated with Chromated Copper Arsenate (CCA)and Three Different Arsenic-Free Preservatives
Creator:
DUBEY, BRAJESH KUMAR
Copyright Date:
2008

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Subjects / Keywords:
Arsenic ( jstor )
Boron ( jstor )
Landfills ( jstor )
Leaching ( jstor )
Lumber ( jstor )
Lysimeters ( jstor )
pH ( jstor )
Soils ( jstor )
Toxicity ( jstor )
Wood ( jstor )
City of Gainesville ( local )

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Source Institution:
University of Florida
Holding Location:
University of Florida
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Copyright Brajesh Kumar Dubey. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
Embargo Date:
12/31/2006
Resource Identifier:
443947240 ( OCLC )

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COMPARISON OF ENVIRONMENTAL IMPACTS OF WOOD TREATED WITH CHROMATED COPPER ARSENA TE (CCA) AND THREE DIFFERENT ARSENIC-FREE PRESERVATIVES By BRAJESH KUMAR DUBEY A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2005

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Copyright 2005 by Brajesh Kumar Dubey

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To the memory of my nephew “Somu”

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ACKNOWLEDGMENTS I am grateful to my advisor, Dr. Timothy Townsend, for his excellent support throughout my academic career at the University of Florida. He helped me get trained in various facets of solid and hazardous waste management, always giving me opportunities to learn something new. He has been a great source of inspiration and a role model. I am thankful for the immense encouragement and financial support that he graciously provided during this study. I would like to express my sincere gratitude to Dr. Helena Solo-Gabriele for her guidance and encouragement during the course of various treated wood projects that we worked together on for the past five years. I would also like to thank my other committee members, Dr. Gabriel Bitton and Dr. R. D. Rhue, for always being available to help and give suggestions whenever I needed them. I thank Dr. J.C. Bonzongo, and Dr. W. Harris for their help. I would like to thank the Florida Center of Solid and Hazardous Waste Management for their support of treated wood research. I wish to thank and acknowledge the help and support of our garbage group members, past and present. I owe much of my academic and personal success to my parents and my family, who, by example, provided me with the motivation and courage to pursue a Ph.D. degree. Special thanks go to my Indian Gainesville family, for their love and support that made my stay in Gainesville so memorable. Finally, the greatest thanks go to my wife, Abhilasha, for her tremendous friendship, encouragement, patience, and unconditional love. iv

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TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................iv LIST OF TABLES .............................................................................................................ix LIST OF FIGURES .............................................................................................................x ABSTRACT .....................................................................................................................xiv CHAPTER 1 INTRODUCTION...................................................................................................1 1.1 Background and Problem Statement..................................................................1 1.2 Research Objective............................................................................................3 1.3 Research Approach............................................................................................5 1.4 Outline of Dissertation.......................................................................................6 2 IMPACT OF SURFACE WATER CONDITIONS ON PRESERVATIVE LEACHING AND AQUATIC TOXICITY FROM TREATED WOOD PRODUCTS.............................................................................................................7 2.1 Introduction........................................................................................................7 2.2 Material and Methods......................................................................................11 2.2.1 Collection of Wood Samples.........................................................11 2.2.2 Collection and Preparation of Leaching Fluids.............................11 2.2.3 Laboratory Leaching Procedures...................................................12 2.2.4 Chemical Analysis.........................................................................13 2.2.5 Toxicity Testing Methodology......................................................14 2.2.6 Determination of Heavy Metal Binding Capacity for Copper (HMBC).........................................................................................15 2.3 Results and Discussion....................................................................................16 2.3.1 Characterization of the Leaching Fluid..........................................16 2.3.2 Total Leached Copper Concentration............................................16 2.3.3 Labile Copper Concentration in Treated Wood Leachate.............20 2.3.4 Aquatic Toxicity of Treated Wood Leachate.................................21 v

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2.3.5 Comparison of Aquatic Toxicity with Leached Copper Concentrations...............................................................................22 2.3.6 Heavy Metal Binding Capacity (HMBC) of Copper in Different Waters 24 2.4 Summary..........................................................................................................25 3 COMPARISON OF RELATIVE RISKS FROM PRESERVATIVE COMPONENTS IN SOIL BELOW STRUCTURES MADE OF CCA, ACQ, CBA AND DOT TREATED WOOD....................................................................36 3.1 Introduction......................................................................................................36 3.2 Material and Methods......................................................................................38 3.2.1 Construction and Setup of Decks...................................................38 3.2.2 Soil Collection and Characterization.............................................39 3.2.3 Soil Column Construction and Set up............................................41 3.2.4 Leachate Analysis..........................................................................42 3.2.5 Dismantling of Soil Columns and Surface Soil Analysis..............43 3.2.6 Calculation for the Percent Mobility and Relative Risk in Soils...44 3.2.7 Calculation of SCTL and GWCTL for Organic Biocides.............44 3.3 Results and Discussion....................................................................................45 3.3.1 Deck Runoff Characterization.......................................................45 3.3.2 Preservative Concentrations in the Soil Leachate..........................47 3.3.3 Mobility of Preservative Components in Different Soils..............49 3.3.4 Concentration of Preservative Components in the Surface Layer of Soil Column...............................................................................51 3.3.5 Relative Risk Assessment for Preservative Components of Different Treated Wood.................................................................52 3.4 Summary..........................................................................................................54 4 COMPARISON OF METAL LEACHING FROM TREATED WOOD WHEN LEACHED WITH MUNICIPAL SOLID WASTE LANDFILL LEACHATE....66 4.1 Introduction......................................................................................................66 4.2 Materials and Methods.....................................................................................69 4.2.1 Sample Collection and Preparation................................................69 4.2.2 Determination of Total Extractable Metal Concentrations............69 4.2.3 Landfill Leachate Collection..........................................................69 4.2.4 Laboratory Leaching Procedures...................................................70 4.2.5 Impact of Solution pH on Leaching...............................................71 4.2.6 Leachate Analysis..........................................................................72 4.3 Results and Discussion....................................................................................72 4.3.1 Total Metal Content in the Sawdust Samples................................72 4.3.2 Landfill Leachate Characterization................................................73 4.3.3 Average Preservative Leaching From Pressure-Treated Wood under Different Leaching Environments.......................................74 4.3.3.1 Chromated copper arsenate treated wood..........................74 4.3.3.2 Alkaline copper quaternary treated wood..........................76 vi

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4.3.3.3 Copper boron azole treated wood......................................77 4.3.3.4 Borate treated wood...........................................................78 4.3.4 Variation of Preservative Leaching with Different Landfill Sites.78 4.3.4.1 Arsenic and Cr leaching as a function of landfill leachate source.................................................................................78 4.3.4.2 Boron leaching as a function of landfill leachate source...80 4.3.4.3 Copper leaching as a function of landfill leachate source.81 4.3.5 Comparison of Leaching by Acidogenic and Methanogenic Leachates........................................................................................83 4.4 Regulatory and Disposal Implications.............................................................84 4.5 Summary..........................................................................................................88 5 COMPARISON OF CCAAND ACQTREATED WOOD DISPOSAL IN CONSTRUCTION AND DEMOLITION DEBRIS LANDFILLS.......................98 5.1 Introduction......................................................................................................98 5.2 Material and Methods....................................................................................100 5.2.1 Lysimeter Construction and Installation......................................100 5.2.2 Lysimeter Composition and Loading...........................................101 5.2.3 Determination of Total Extractable Metal Concentrations in Untreated and Treated Wood.......................................................101 5.2.4 Lysimeter Monitoring, Water Addition and Sample Collection..102 5.2.5 Laboratory Batch Leaching Procedures.......................................102 5.2.6 Leachate Analysis........................................................................103 5.3 Results and Discussion..................................................................................103 5.3.1 Total Metal Content in the Co-Disposed Wood Waste...............103 5.3.2 Temporal Variation of Leachate Parameters...............................104 5.3.3 Arsenic, Chromium, Boron and Copper Leaching Over Time....107 5.3.4 Batch Leaching Test Results for As, Cr, Cu and B.....................109 5.4 Implication for Management..........................................................................112 5.5 Summary........................................................................................................114 6 SUMMARY AND CONCLUSION....................................................................128 6.1 Summary........................................................................................................128 6.2 Conclusion.....................................................................................................130 6.3 Future Work...................................................................................................131 APPENDIX A ADDITIONAL SURFACE WATER STUDY DATA........................................133 A.1 Leaching Solution Collection and Leaching Setup.......................................133 A.2 Detailed Procedure for Analysis...................................................................134 A.2.1 Labile Cu Measurement.................................................................134 A.2.2 MetPLATE Procedure................................................................135 A.2.3 Assessing Cu Binding Capacity of Different Surface Waters.......136 vii

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A.3 Arsenic and Chromium Concentrations in CCA-Treated Wood Leachates.139 A.4 Boron Concentration in the ACQand CBA-Treated Wood Leachates.......140 A.5 Labile Copper as a Function of Alkalinity and Total Organic Carbon.........141 B ADDITIONAL MATERIAL FOR RELATIVE RISK FROM VARIOUS TREATED WOOD PRODUCTS........................................................................142 B.1 Construction of Decks...................................................................................142 B.2 Organic Analysis...........................................................................................145 B.2.1 Method for Determining DDAC Concentrations in ACQ...........145 B.2.2 Method for the Determination of Tebuconazole..........................147 B.2.3 Calculation of Soil Cleanup Target Level for DDAC and Tebuconazole...................................................................148 B.2.4 Calculation of Groundwater Cleanup Target Level for DDAC and Tebuconazole............................................................149 B.2.5 Soil Cleanup Target Level (SCTL) and GWCTL Values for Preservative Components.................................................150 C ADDITIONAL MATERIAL FOR TREATED WOOD LEACHING IN MSW LEACHATE........................................................................................................156 C.1 Impact of pH on Copper Leaching from ACQ and CBA Treated Wood Sawdust Samples.....................................................................................156 C.2 Copper Leaching as a Function of Various Leachate Parameters.................158 D ADDITIONAL SIMULATED CONSTRUCTION AND DEMOLITION DEBRIS LANDFILL STUDY DATA................................................................172 D.1 Lysimeter Construction and Installation.......................................................172 D.2 Experimental Site Detail...............................................................................174 D.3 Lysimeter Loading and Compaction.............................................................174 D.4 Predicted Cu Concentration in Batch Leaching Tests..................................175 LIST OF REFERENCES.................................................................................................176 BIOGRAPHICAL SKETCH...........................................................................................186 viii

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LIST OF TABLES Table page 2-1 Characterization of leaching solutions for water quality parameters.........................28 3-1 Physical and chemical properties of soil horizons used in the study..........................56 3-2 Percentage mobility of preservative components calculated at the end of the experiment................................................................................................................56 3-3 Preservative components concentrations (mg/kg) in soil surface layer.....................57 3-4 Risk factor calculated for preservative components based on surface layer concentration and florida soil clean up target levels (SCTLs a )................................57 4-1 Summary of leaching test procedures used in this study............................................90 4-2 Composition of landfill leachate collected from twenty six landfill sites..................91 4-3 Comparison of preservative leaching using acidogenic and methanogenic leachates for leaching...............................................................................................92 5-1 Waste composition of C&D simulated lysimeters...................................................116 B-1 Summary of toxicological data a for DDAC and tebuconazole................................148 B-2 SCTL and GWCTL values for preservative components........................................150 ix

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LIST OF FIGURES Figure page 2-1 Total copper leaching from CCA treated wood products in different leaching solutions...................................................................................................................28 2-2 Total copper leaching from ACQ treated wood products in different leaching solutions...................................................................................................................29 2-3 Total copper leaching from CBA treated wood products in different leaching solutions...................................................................................................................29 2-4 Labile copper concentration in the treated wood leachate (error bars represent standard deviation of four replicates).......................................................................30 2-5 MetPLATE toxicity of treated wood leachates as a function of leaching solution (error bars represent standard deviation of four replicates).....................................31 2-6 Total copper concentrations (mg/L) vs. toxicity EC 50 for CCA-treated wood leachates...................................................................................................................32 2-7 Total copper concentrations (mg/L) vs. toxicity EC 50 for ACQ-treated wood leachates...................................................................................................................32 2-8 Total copper concentrations (mg/L) vs. toxicity EC 50 for CBA-treated wood leachates...................................................................................................................33 2-9 Labile copper concentrations (mg/L) vs. toxicity EC 50 for treated wood leachates...34 2-10 Copper binding capacity of different extraction solutions when copper was spiked to natural waters. .........................................................................................35 3-1 Soil sample collected from a soil pit at an ifas research station.................................58 3-2 Soil column setup in laboratory for three soil horizons..............................................58 3-3 Copper concentration in deck runoff samples............................................................59 3-4 Boron concentration in deck runoff samples..............................................................59 3-5 DDAC and tebuconazole concentration in deck runoff samples................................60 x

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3-6 Arsenic and chromium concentration in deck runoff samples...................................60 3-7 Copper concentrations in soil column eluents............................................................61 3-8 Cumulative copper concentrations in soil column eluents.........................................62 3-9 Arsenic and chromium concentrations in soil column eluents...................................63 3-10 Relative risk factors on sandy soil when surface soil concentration was compared to SCTL...................................................................................................64 3-11 Relative risk factors for potential groundwater contamination using data from sandy soil horizon column eluent concentrations....................................................65 3-12 Relative risk factors for potential groundwater contamination using data from deck runoff concentrations.......................................................................................65 4-1 Average preservative leaching wood products under several leaching environments (A) CCA, (B) ACQ, (C) CBA, (D) DOT..........................................93 4-2 Arsenic and chromium leaching from CCA-treated wood samples leached with various landfill leachates as the leaching fluid.........................................................94 4-3 Boron leaching from ACQ-, CBAand DOTtreated wood samples leached with various landfill leachates as the leaching fluid.........................................................95 4-4 Cu leaching from pressure treated wood samples leached with several landfill leachates as the leaching fluid..................................................................................96 4-5 Cu concentrations in the extracts as a function of landfill leachate -ammonia..........97 5-1 Water addition/leachate production for simulated C&D landfills over time............117 5-2 pH and ORP of leachate over time from simulated C&D landfills..........................118 5-3 Conductivity of leachate over time from simulated C&D landfills..........................119 5-4 COD and sulfide of leachate over time from simulated C&D landfills...................120 5-5 TDS and alkalinity of leachate over time from simulated C&D landfills................121 5-6 Sulfate concentration of leachate over time from simulated C&D landfills............122 5-7 Arsenic concentrations in the leachates from three lysimeters over time................123 5-8 Chromium concentrations in the leachates from three lysimeters over time...........123 5-9 Boron concentrations in the leachates from three lysimeters over time...................124 xi

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5-10 Preservative leaching from CCA-treated wood under batch leaching tests of TCLP, SPLP and leaching with a C&D debris landfill leachate............................125 5-11 Copper and Boron leaching from ACQ-treated wood under batch leaching tests of SPLP, TCLP and with a C&D debris landfill leachate......................................126 5-12 Arsenic concentration in CCA lysimeter leachates from three C&D lysimeter projects...................................................................................................................127 A-1 Sampling locations for surface water samples collected for leaching solutions used in the study.....................................................................................................133 A-2 A typical leaching setup for the treated wood blocks..............................................133 A-3 Calibration curve for labile cu measurement in treated wood leachates.................134 A-4 Method for computing EC50 (From Townsend et al., 2003c)................................137 A-5 Step by step procedure for cu binding capacity measurement in different surface waters.....................................................................................................................138 A-6 Arsenic and Chromium concentration in CCA leachates from different surface waters (The error bars represent the standard deviation of four replicates)...........139 A-7 Boron concentration in ACQ and CBA leachates from different surface waters (The error bars represent the standard deviation of four replicates)......................140 A-8 Labile Copper as a function of alkalinity and TOC of leaching solutions..............141 B-1 Plan view of a deck (Dimensions in inches)............................................................143 B-2 Sectional view of a deck (Dimensions in inches)....................................................143 B-3 As built decks...........................................................................................................144 B-4 Tubs in which decks were placed............................................................................144 B-5 Cumulative copper concentrations in deck runoffs.................................................151 B-6 Cumulative boron concentrations in deck runoffs...................................................151 B-7 Cumulative arsenic and chromium concentrations in deck runoffs.........................152 B-8 Cumulative DDAC and tebuconazole concentrations in deck runoffs....................152 B-9 Cumulative copper concentrations in soil column eluents......................................153 B-10 Cumulative boron concentrations in soil column eluents......................................154 xii

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B-11 Cumulative arsenic and chromium concentrations in soil column eluents............155 C-1 pH impact on Cu leaching from ACQ-treated wood sawdust samples...................157 C-2 pH impact on Cu leaching from CBA-treated wood sawdust sample.....................157 C-3 Copper leaching from treated wood as a function of leachate ammonia.................159 C-4 Copper leaching from treated wood as a function of leachate alkalinity.................161 C-5 Copper leaching from treated wood as a function of initial leachate pH.................163 C-6 Copper leaching from treated wood as a function of leachate conductivity............165 C-7 Copper leaching from treated wood as a function of leachate ORP........................167 C-8 Copper leaching from treated wood as a function of leachate TDS........................169 C-9 Copper leaching from treated wood as a function of leachate COD.......................171 D-1 Schematic of lysimeter............................................................................................172 D-2 Lysimeter construction photographs........................................................................173 D-3 Lysimeter placement inside the landfill...................................................................173 D-4 Lysimeter loading and compaction of waste components.......................................174 xiii

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Abstract of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy COMPARISON OF ENVIRONMENTAL IMPACTS OF WOOD TREATED WITH CHROMATED COPPER ARSENATE (CCA) AND THREE DIFFERENT ARSENIC-FREE PRESERVATIVES By Brajesh Kumar Dubey December 2005 Chair: Timothy G. Townsend Major Department: Environmental Engineering Sciences Recently, the treated wood industry phased out the use of arsenic (As)-preserved wood for residential uses in favor of copper-preserved wood. Pressure-treated wood products of CCA and three Asand Crfree preservatives, alkaline copper quaternary (ACQ), copper boron azole (CBA), and disodium octaborate tetrahydrate (DOT), were studied, and the possible environmental impacts from these treated wood products were compared under identical in-service and disposal scenarios. The scenario of treated wood use in an aquatic ecosystem was simulated in laboratory conditions. Part of the present study is focused on studying the effect of natural water chemistry on chemical leaching and aquatic toxicity when a treated wood structure is used in these conditions. In general, it was found that the major part of the total copper leached was present as a complex with inorganic or organic ligands present in water and was not bio-available. xiv

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The relative risks from preservative components of various wood treatment chemicals in soil for direct exposure and groundwater contamination were evaluated by using a deck and soil column experiment. Arsenic from CCA-treated wood was found to pose highest relative risk in terms of direct exposure. In terms of potential groundwater contamination boron (B) from DOT-treated wood and As from CCA-treated wood posed a greater relative risk compared to Cu and organic biocides from ACQand CBA-treated wood. The impact of pressure treated wood on leachate quality when disposed in landfills was studied. Simulated C&D columns were constructed for CCAand ACQtreated wood co-disposal scenario and the treated wood sawdust of CCA-, ACQ-, CBAand DOT-treated wood were leached using leachates collected from various MSW landfill sites in Florida. In batch leaching tests higher Cu concentration was measured in the extract, but Cu was below the detection limit in C&D column leachate throughout the duration of experiment. Elevated As, Cr and B concentration in both batch and column leaching tests indicate potential groundwater contamination in an unlined landfill and leachate management and treatment problem for lined landfill. xv

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CHAPTER 1 INTRODUCTION 1.1 Background and Problem Statement Wood is a favored structural material because of qualities such as ready availability and high strength-to-weight ratio. However, most wood species are very prone to fungal degradation and insect damage when in contact with the ground or in wet environments, and hence need preservative treatment to extend their service life when used in such a fashion. The service life of an untreated southern yellow pine fence post in the environment is between one and three years, whereas a post treated with preservatives can last from twenty to thirty years (Cooper and Ung, 1993). Until recently, chromated copper arsenate (CCA) was the most common wood treatment chemical used by the wood preservation industry. Concerns over the risks to human health and the environmental impact of the heavy metals used in CCA prompted the industry to voluntarily withdraw CCA from most residential uses in 2004 (Cooper, 1991; Merkle et al., 1993; Breslin, 1996; Stillwell and Gorny, 1997; Adler-Ivanbrook, 1998; Lebow et al., 1999; Solo-Gabriele et al., 2002; USEPA, 2002; Lebow et al., 2003; Townsend et al., 2003a, Khan et al., 2004; and Song et al., in-press). CCA-treated structures manufactured prior to the phase-down will, however, remain in the environment for many years, and products exempted from the phase-down will continue to be produced (e.g., poles, piles, round posts). CCA-treated wood may thus continue to impact the environment during use and disposal, if not managed properly. 1

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2 The wood preservatives available on the market as replacements to CCA include alkaline copper quaternary (ACQ), copper boron azole (CBA), and borate-based preservatives such as disodium octaborate tetrahydrate (DOT). Alkaline copper quaternary and CBA utilize copper (Cu) as a primary biocide, and as secondary biocide use didecyldimethyl ammonium chloride (DDAC) and tebuconazole [C 16 H 22 ClN 3 O] respectively. These organic compounds interact synergistically with the Cu to improve the efficacy of the treatment chemical by providing protection against Cu-tolerant fungi and other decay fungi (Solo-Gabriele et al., 2000). A supplemental biocide, boric acid, is added to CBA to provide some initial protection against termites and other decay causing organisms. Boric acid is also added to ACQ to serve as a corrosion inhibitor and is not claimed by the manufacturers of ACQ as to be used as an active biocide. Several borate-based preservatives such as borax, boric acid, disodium octaborate tetrahydrate (DOT) and sodium borate are also used as wood preservatives. Borates are effective preservatives against the decay caused by fungi and insects. Borate preservatives are diffusible, and with appropriate treating practices, they can achieve excellent penetration in species that are difficult to treat with other preservatives (Lebow and Tippie, 2001). Although some non soluble forms such as zinc borate is used in wood based composite material, however, most of the borate forms used for wood treatment remains water soluble and thus readily leache out in soil or rainwater. Recently, one of the borate-treated wood manufacturers developed a product called “Envirosafe”, which they claim has a “patented binding agent” that assure the retention of effective levels of the preservative’s active ingredient (DOT) and provides a long-term barrier against fungi, insects and termites. In the present study, this particular borate-treated wood was used.

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3 When seeking alternatives to CCA, a primary concern is whether the new treatment chemical is as effective as CCA in terms of preservation. After comparing several characteristics of treated wood products, it was found that the alternative chemicals perform nearly as well as CCA for standardized applications, but that they are slightly more expensive (Solo-Gabriele et al., 2000). Copper or B-based alternatives do not contain the carcinogenic elements arsenic (As) and chromium (Cr), thus lending these alternative chemicals an advantage over CCA with respect to human health exposure issues and waste management issues. Copper leaching from the Cu-based alternatives is a potential concern, however, when treated wood is used in an aquatic environment due to the toxicity of Cu to aquatic organisms. With the voluntary withdrawal of CCA-treated wood from most residential applications, the use of alternative treated (mainly copper or boron-based) wood has increased. Substantial research has been done evaluating environmental impact of CCA-treated wood in different use and disposal scenarios in the past decades. Minimal similar research is available evaluating the new Cu-or B-based alternative treated wood products in similar scenarios. Further research is needed to understand the potential environmental impact of these new alternatives under different environmental scenarios and to compare their impacts to that from CCA-treated wood under similar conditions; this will help make decisions on the proper use and disposal of these treated wood products. 1.2 Research Objective The objective of this doctoral research was to compare and contrast the potential environmental impacts of CCA-treated wood with that of wood treated with ACQ, CBA and DOT. The chemicals chosen for the study were based on their availability in the

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4 market and their potential candidacy for replacing CCA. This research addresses several of the use and disposal concerns related to preservative treated wood. In a natural aquatic system, preservative chemicals from treated wood can leach out, possibly resulting in an increase in preservative concentration in the water body which at elevated concentrations may be toxic to aquatic life. The chemical environment of the natural aquatic system can possibly play a major role in the bio-availability of a leached preservative chemical. The first objective of this dissertation research was to study the impact of surface water conditions on chemical leaching and aquatic toxicity of leachates produced from different pressure-treated wood products. Preservative chemicals that leach from a treated wood structure could potentially increase the preservative concentration in the underlying soil and eventually could possibly lead to groundwater contamination. Various factors such as pattern of rainfall, UV exposure of the structure, temperature, and humidity, affect the leaching pattern of preservatives when exposed to natural conditions. Physical and chemical properties of the soil type influence the migration of preservative chemicals in soil. These factors make the comparison of results from various studies conducted under different environmental conditions very difficult. Relative risk of preservative components in soils was studied in identical settings for CCA-, ACQ-, CBAand DOT-treated wood products. There is a growing concern over the environmental impacts of pressure-treated wood disposed in unlined construction and demolition debris (C&D) landfills and municipal solid waste (MSW) landfills. The potential for groundwater contamination at unlined C&D debris landfills and the impact of elevated metal concentration in leachate

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5 at MSW landfills raises the question of appropriateness of disposing treated wood products in these landfills. Leaching conditions of C&D and MSW environments has been simulated and the effect of preservative components on leachate quality was studied. 1.3 Research Approach The impact of surface water conditions on chemical leaching and aquatic toxicity of treated wood products was studied by leaching wood blocks treated with CCA, ACQ, and CBA in water samples collected from different Florida surface waters. All of the leaching fluids were characterized for various water quality parameters. Total Cu, labile Cu and heavy metal specific toxicity using MetPLATE TM assays were evaluated in the leachates produced. Additionally, the heavy metal binding capacity (HMBC) of the leaching fluids was determined following a modified procedure based on the EPA’s water effect ratio (WER) method. The relative risk of preservative components in soil below treated wood structures was studied by calculating the relative risk factors for different components present in these preservative chemicals. A deck and soil column study was used to collect the data for preservative component concentration in soil, soil column eluents and deck runoff samples. Risk factor was calculated as a ratio of element concentration and corresponding risk based standards of soil cleanup target level (SCTL) and groundwater cleanup target level (GWCTL). For the organic biocides these risk based standards were derived using the same procedure as used by Florida department of environmental protection (FDEP) for different elements of environmental concern. The relative risks from different wood preservatives were compared and discussed.

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6 The impact of treated wood on leachate quality at C&D debris and MSW landfills was evaluated in two experiments. One experiment compared the leachate quality of two simulated C&D debris landfills, one containing CCAand the other ACQ-treated wood. A control lysimeter column with untreated wood was also used for comparison. In a second experiment, sawdust samples of CCA, ACQ, CBA and DOT treated wood were leached with MSW landfill leachate collected from 26 different sites. Untreated wood sawdust was also used as a control and the metal concentrations from the leaching experiment was compared with the regulatory batch leaching tests of toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP) and California waste extraction test (WET). 1.4 Outline of Dissertation This PhD dissertation is presented in 6 chapters, including the present chapter which covers the background, objectives and approaches for this research. Chapter 2 presents the impact of surface water conditions on preservative concentrations and aquatic toxicity of treated wood leachate. Concentration of preservative components in soils below treated wood structures is presented in Chapter 3. Chapter 4 presents the evaluation of leachate quality produced on leaching of treated wood sawdust with various municipal solid waste landfill leachates as leaching fluid. Chapter 5 compares the leachate quality of simulated C&D landfills on co-disposal of CCA and ACQ treated wood with other waste streams of C&D landfill. Chapter 6 presents a summary and the conclusions of all of these research experiments. The literature cited as references to this document are included at the end of this document. Appendix A through D contains additional information for chapters 2 through 5.

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CHAPTER 2 IMPACT OF SURFACE WATER CONDITIONS ON PRESERVATIVE LEACHING AND AQUATIC TOXICITY FROM TREATED WOOD PRODUCTS 2.1 Introduction The preservation of wood serves the intended purpose of preventing biological decay, but it may also pose a potential environmental risk. Preservative components leach from pressure-treated wood products when exposed to water (Warner and Soloman, 1990; Cooper, 1991; Adler-Ivanbrook and Breslin, 1998; Lebow et al., 1999; Hingston et al., 2001; Stook et al., 2004, 2005; and Townsend et al., 2004a, 2005). Until recently, chromated copper arsenate (CCA) was the most common wood treatment chemical used by the wood preservation industry in the US. The copper (Cu) in CCA-treated wood helps prevent fungal attack, chromium (Cr) “fixes” or binds the chemical to the wood and the arsenic (As) acts as an insecticide (Milton, 1995). Concerns over human-health and the environmental impact of the preservative elements (especially As) used in CCA (Cooper, 1991; Merkle et al., 1993; Breslin and Adler-Ivanbrook, 1996; Stillwell and Gorny, 1997; Adler-Ivan brook and Breslin, 1998; Roberts and Ochoa, 2001; Lebow et al., 2003; Townsend et al., 2003a; Zartarian et al., 2003; Khan et al., 2004; and Song et al.-in press) prompted the industry to withdraw the use of CCA in connection with most residential uses starting in 2004 (USEPA, 2002). Wood products treated with Cu-based preservatives are now widely used as a result of the phase down of CCA-treated wood. Among the new generation of wood preservative solutions, alkaline copper quaternary (ACQ) and copper boron azole (CBA) 7

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8 are the most popular Cu-based preservatives in current use. Although Cu-based alternatives do not leach As or Cr, they do leach several times more Cu than CCA-treated wood (Stook et al., 2004; 2005). This may be partly due to the absence of Cr, which partly oxidizes the lignocellulose material to provide relatively strong binding sites for Cu in CCA-treated wood (Schultz and Nicholas 2003). Copper is known to be toxic to a variety of aquatic organisms at low concentrations (Flemming and Trevors, 1989). Recent studies comparing the chemical leaching and aquatic toxicity of different wood preservatives (Stook et al., 2004; 2005) found that the Cu-based preservatives leached more Cu than CCA-treated wood, and that the aquatic toxicity of the leachates correlated with total Cu concentrations. Though the elimination of As and Cr from these alternative preservatives may reduce the risk posed by direct human contact and from a waste disposal standpoint, the additional Cu leaching may possibly present a greater concern for aquatic ecosystems (Flemming and Trevors, 1989; Weis and Weis, 1995; Stook et al., 2005). Although Cu can have an impact on aquatic organisms, several physical and chemical phenomena can occur that might limit its toxicity. Dissolved Cu tends to complex with inorganic and organic ligands such as CO 3 2, OH , humic and fulvic acids (Newell and Sander, 1986; Donat et al., 1994; Chow et al., 1996). The Cu in these compounds is often much less bioavailable to aquatic organisms and, thus, is less toxic (Flemming and Trevors, 1989; Ma et al., 1999; Devez et al., 2005). The Cu 2+ ion is generally considered the most environmentally relevant species to the aquatic system and the most toxic form of Cu to aquatic life. It is common in many natural waters for dissolved Cu to be predominantly in the complexed state and hence less toxic than the

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9 total copper concentrations alone would suggest (Arnold, 2005). The type of water that the copper leaches into can have a significant impact on its bioavailability and toxicity to aquatic organisms (Flemming and Trevors, 1989; Tao and Liang, 1997). A preliminary study by Dubey et al. (2005) reported lower Cu concentrations and resulting aquatic toxicity of treated wood leachates when leached with two Florida surface water samples as compared to de-ionized (DI) water. Although free Cu 2+ is considered the most toxic form of Cu (Brand et al., 1986), several studies have reported that other forms of Cu are also likely to contribute to the Cu toxicity (Brown and Markich, 2000; Eriksen et al., 2001; Lorenzo et al., 2002; Hauri and Horne, 2004; and Devez et al., 2005;). Forms of Cu identified in these studies to contribute to toxicity include Cu 2+ , CuOH + , CuCO 3 0 , and CuCO 3 0 OH . Loosely bound fractions (free and readily reversible complexes (labile)) of Cu (which include the forms mentioned here) have been measured in a few studies and have shown to correlate with toxicity (Deaver and Rodgers, 1996; Devez et al., 2005). Since a measurement of total Cu concentration alone may not provide a good indication of toxicity posed by Cu in aquatic systems, several studies have used ion-selective electrode (ISE) for the measurement of Cu 2+ . Depending on the pH of water, other forms of Cu may also exist. Labile Cu (the loosely bound Cu) gets back to solution as free Cu 2+ when a water sample is slightly acidified (Stumm and Morgan, 1996). Wiese and Schwedt (1997) measured the Cu 2+ concentrations in wine samples acidified to a pH = 4, and the combined free Cu 2+ and labile Cu measurement in the wine samples was also conducted using the differential pulse anodic-stripping voltammetry (DPASV) methodology. The two measurements were found to follow a similar trend. Rozan et al. (1999) also found good

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10 correlation of the Cu data generated with DPASV and ISE methodology when these two methods were compared for the measurement of Cu complexation characteristics of natural organic matter (NOM) in fresh water systems. Since water chemistry is well established to affect bioavailability and hence toxicity of Cu in aquatic systems, the water effect ratio (WER) was developed and used by the US EPA (US EPA 1982, 1984, 1994) to assess the bioavailability of metal in aquatic environments. It is defined as the ratio of the 50% effect (for example LC 50 ) derived from testing the toxicity of an element to an indicator organism in water to 50% effect derived from testing the same organism in laboratory water. If WER for a water body is 2.0, it implies that the water body will exhibit half the toxicity as compared to laboratory water for the same concentration of the concerned element. This approach has been used to derive site specific water quality criteria for Cu (Sinclair, 1989). A similar simplified approach as WER to determine metal bioavailability has been developed (termed heavy metal binding capacity (HMBC)) using MetPLATE (a heavy metal specific aquatic toxicity test, presented in detail in the subsequent section) to quantify the influence of site-specific water quality parameters on metal bioavailability (Huang et al., 1999). The HMBC assay has been validated with surface water samples, with a direct relationship identified between water quality and bioavailability (Huang et al., 1999). Recently, HMBC assay has also been used for evaluating the binding capacity of municipal solid waste (MSW) landfill leachates (Ward et al., 2005). The objective of the research presented in this chapter was to evaluate the impact of surface water conditions on preservative leaching and aquatic toxicity of treated wood leachates. Measurements were taken of total and labile Cu concentrations in the treated

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11 wood leachates from CCA-, ACQ-, and CBA-treated wood when leached with different Florida surface waters. Heavy metal specific aquatic toxicity was quantified for treated wood leachates and HMBC assays were conducted for Cu in the surface waters used as leaching solutions. The data generated can be used to evaluate the risk from treated wood use in different aquatic conditions. 2.2 Material and Methods 2.2.1 Collection of Wood Samples Samples of southern yellow pine treated with CCA, ACQ, and CBA were prepared using lumber purchased from home improvement stores in Gainesville, Florida. Blocks of approximately 80 g each were obtained by cutting pieces of dimensional lumber treated with CCA, ACQ or CBA using a power saw. The average surface area of wood blocks was in the range of 140-150cm2. For each wood type, a separate blade was used to cut the wood sample. Sawdust samples were collected for each wood type for subsequent total Cu determination. 2.2.2 Collection and Preparation of Leaching Fluids Eleven different leaching solutions were used in the study. Water samples were collected from two rivers (the Kissimmee River (KR) and the St. Johns River (SJR)), three lakes (Lake Okeechobee (LO), Lake Alice (LA) and Lake Wauberg (LW)), two wetlands (WL-1 and WL-2), and from the Atlantic Ocean (AO) (Figure A-1 in appendix A). All the leaching solutions were passed through a paint strainer to remove sediments, weeds and leaves etc., if any, prior to leaching. In an earlier study it was shown that landfill leachates rich in organic and inorganic ligands, reduced bioavailability of heavy metals including Cu (Sletten et al., 1995; Ward et al., 2005). For comparison, a landfill leachate was also collected from a local Florida Landfill (the term “LL” will be used for

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12 this leaching solution in this chapter) to be used as a leaching solution. Each sample was collected in a 20-L container with minimum head space and transported to the solid and hazardous waste laboratory at the University of Florida. The leaching experiments were performed within 24 hours of extraction solution collection. De-ionized water (DI) and moderately hard water (MHW) were also used as leaching solutions. The MHW leaching solution was prepared in the laboratory as per EPA Method 600/4-90/027 (US EPA, 1991) by mixing several grams of sodium bi-carbonate (NaHCO 3 ) , calcium sulfate (CaSO 4 ) , anhydrous magnesium sulfate (MgSO 4 ) and a 0.5 mM potassium chloride (KCl) solution with 18 liters of nanopure water in a 20-L carboy container. 2.2.3 Laboratory Leaching Procedures Four replicate tests were conducted for each wood-leaching fluid combination. Block samples were used for leaching tests as has been performed in previous work (Kennedy and Collins, 2001; Stook et al., 2004) reported in literature. Each test consisted of an 80 g wooden blocks immersed in a 2-L jar with 1.6 L of leaching solution, resulting in a liquid to solid ratio (L/S) of 20:1. The L/S of 20 was chosen in order to have the same ratio as used in the AWPA standard E-11 test (AWPA, 1987) and EPA tests of synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) (EPA, 2003). Wooden blocks were kept submerged in the leaching solution by using a glass beaker upside down as shown in Figure A-2 of Appendix A. After 24 hours, the resulting leachate was collected without filtration and split into two aliquots; one aliquot was collected in an acid rinsed container and preserved with nitric acid to a pH below 2.0 for metal analysis and the second aliquot was collected in an amber glass bottle and kept unpreserved for labile Cu measurement and toxicity testing. Each sample was assayed for heavy metal toxicity using MetPlate either within 24

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13 hours of sample collection, or the sample was stored in a freezer at -40 O C until MetPLATE analysis. 2.2.4 Chemical Analysis The sawdust generated when cutting block specimens was analyzed for its total Cu content. This was accomplished by digesting 2g sub samples in triplicates using EPA Method 3050B and analyzing the digested samples using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) as per EPA Method 6010B (US EPA, 2003). The total Cu concentration in wooden blocks were 1330 70 mg-Cu/kg for CCA, 2860 85 mg-Cu/kg for ACQ and 5420 120 mg-Cu/kg for CBA treated wood. The eleven leaching solutions used for the leaching tests were characterized for different water quality parameters including pH, total dissolved solids (TDS), alkalinity, hardness, chloride, total organic carbon (TOC), chemical oxygen demand (COD), and turbidity (in NTU). US EPA methods (US EPA, 2003) and other standard methods (APHA, 1995) were employed as applicable. Copper, As, Cr and B concentrations in the treated wood leachates and the leaching solution blanks were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES Thermo Electron Corporation, Trace Analyzer, US EPA Method 6010B) after digesting the aqueous leachate samples as per US EPA Method 3010A (US EPA, 2003). The detection limit for Cu, As, Cr and B were 4 g/L, 12 g/L, 4 g/L and 6 g/L respectively. The Cu concentration is presented and discussed in this chapter, concentrations of other elements are included in Appendix A. Ion-specific electrode (ISE) for Cu 2+ has been used extensively in previous research for free Cu 2+ determination in aqueous samples (Chow et al., 1996; Wiese and Schwedt, 1997; Rozan et al., 1999; and Eriksen et al., 2001). A similar approach was used to

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14 measure the labile Cu concentration in the treated wood leachate samples using the ISE. The Cu 2+ electrode measures the free Cu ion activity in solution and gives the response in a mV scale. When the pH of an aqueous sample is reduced to pH<= 4, part of the loosely bound Cu (readily reversible complex) will get released and come back in solution as free Cu 2+ (Stumm and Morgan, 1996). The free Cu 2+ ion activity was measured and recorded using the electrode for each treated wood leachate (with pH reduced to pH=4). A detailed procedure of the labile Cu measurement along with an example of the calibration curve has been included in Appendix A. 2.2.5 Toxicity Testing Methodology MetPLATE is a heavy metal specific aquatic toxicity assay based on inhibition of -galactosidase activity in an E. coli strain (Bitton et al., 1994). The use of MetPLATE for evaluating aquatic toxicity of treated wood leachate has been demonstrated before (Stook et al., 2004). The MetPLATE kit contains a lyophilized bacterial reagent, chlorophenol red galactopyranoside (CPRG) that serves as the substrate for -galactosidase and moderatly hard water (MHW) as a diluent. The bacterial reagent is rehydrated with 5-mL of diluent (moderately hard water) and thoroughly mixed by vortexing. A 100-L aliquot of the bacterial reagent was added to a 900-L aliquot of the leachate or its appropriate dilution in a test tube and mixed by vortexing. Test tubes were incubated for 90 minutes at 35 0 C. A 200-L aliquot of the suspension (leachate + bacteria) was transferred to a 96-well microplate to which 100 L of CPRG; (the enzyme substrate) was added followed by shaking. The microplate was incubated at 35 C for color development. Conversion of the yellow substrate (CPRG) to the purple product (chlorophenol red) was quantified at 570 nm using a kinetic microplate reader (make Molecular Devices). A negative control of moderately hard water and a positive control

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15 of 1 mg/L Cu were used with each set of analysis. The detailed experimental procedure has been included in Appendix A. EC 50 indicates the 50% inhibition of enzyme activity observed in the test. Higher EC 50 value would indicate lower toxicity. In this chapter the toxicity values have also been presented as Toxicity Unit (TU) which is derived from EC 50 using the equation below. Higher TU values would indicate higher aquatic toxicity. 50EC100TU (1) 2.2.6 Determination of Heavy Metal Binding Capacity for Copper (HMBC) HMBC quantifies the decrease in heavy metal bioavailability and thus toxicity in aquatic environments, and is dependent on physico-chemical parameters such as pH, alkalinity, hardness, and the presence of complexing ligands (Huang et al., 1999). The HMBC was measured using a modified version of the protocol developed by Huang et al., (1999). Treated wood leachate of CCA-, ACQ-, and CBA-treated wood was produced using DI water as the leaching solution and this leachate was used as the metal spike solution for the receiving waters (different surface waters used in the study). The rest of the procedure was similar as followed in the study by Huang et al., (1999) and Ward et al., (2005). Three sets of HMBC tests were conducted for each surface water sample, one each for three wood types (CCA, ACQ and CBA). Detailed step by step procedures are presented in Appendix A. Receiving water was spiked with treated wood DI leachate and mixed at 160 rpm for 60 minutes. Several dilutions were prepared using the mixed treated wood leachate with the surface water samples collected and also with MHW. Aquatic toxicity (EC 50 ) values were obtained following the MetPLATE protocol, as previously described. The HMBC for Cu was expressed as the ratio of the

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16 EC 50 of treated wood leachate in the site water sample to the EC 50 of the same leachate in MHW, as expressed in the following equation: Water HardModerately50ECSampleWater Site50ECHMBC (2) 2.3 Results and Discussion 2.3.1 Characterization of the Leaching Fluid Table 2.1 presents the results of the leaching solutions characterization. The pH of the water samples used for leaching was in the neutral range (varied from 6.39 to 8.14). Comparatively higher concentrations of various parameters were measured for LL and AO waters as compared to other water samples with the lowest concentrations measured in the DI and MHW leaching solutions. Copper concentrations were below the detection limit of the ICP-AES in almost half of the leaching solutions with the exception of LA, LW, WL-1, WL-2 and LL. The characterization of the leaching solutions was carried out to identify the range of water quality parameters which can be used along with the leaching results presented in the next section to predict the possible leaching potential of a certain wood treatment in a given water body. 2.3.2 Total Leached Copper Concentration Figures 2-1 through 2-3 present the total copper leached with different leaching solutions for CCA (Figure 2-1), ACQ (Figure 2-2) and CBA (Figure 2-3) treated wood blocks. Copper leaching was highest (1.0 0.02 mg/L for CCA and 9.2 1.2 mg/L for ACQ) when CCA and ACQ blocks were leached with landfill leachates as the leaching solution. This was not unexpected as Cu is known to make stable soluble complexes with organic and inorganic ligands present in landfill leachate (Adriano, 2001). The lowest concentration of Cu (0.20 0.05 mg/L) measured in the leachate was produced with

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17 MHW as the leaching fluid for the CCA-treated wood blocks. The highest pH was recorded for the MHW treated wood leachates compared to other treated wood leachates (except for AO, LL); this could possibly be the reason for lower concentration of Cu in this leachate. A similar observation was also made by Townsend et al. (2004) when CCA-treated wood sawdust was leached over a range of different pH values, higher Cu concentration was measured in leachates with lower pH. The CCA-treated wood leachates (final pH = 7.39) produced with the AO leaching solution had higher Cu concentration compared to MHW treated wood leachates (final pH = 6.95), and this was attributed to the presence of ligands (Cl , Br ), which are capable of forming stable soluble Cu complexes (Stumm and Morgan, 1996). Similar observations were also made with ACQ-treated wood leachate in seawater solution. Copper concentrations measured in the other nine leaching solutions ranged from 0.42 0.14 mg/L to 0.82 0.19 mg/L for CCA-treated wood and varied from 3.3 0.75 mg/L to 5.8 0.14 mg/L for ACQ-treated wood. Although the final pH was slightly higher (pH = 6.27) for WL-1 CCA leachate compared to WL-2 CCA leachate (pH=6.15), higher Cu concentration in WL-1 CCA leachate was observed, which could possibly be due to comparatively high organic matter (TOC = 173 mg/L for WL-1 compared to 57 mg/L for WL-2) present in the WL-1 sample. The final pH of the leaching solution and the presence of inorganic and organic ligands influenced Cu leaching from CCAand ACQ-treated wood blocks. The Cu concentrations from different natural waters were statistically significantly different ( = 0.05, P<0.01, ANOVA analysis). Stastistical difference were also observed for individual means of CCA DI and CCA MHW leachates

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18 ( = 0.05, P= 0.034) for the means of CCA WL-1 and CCA WL-2 leachates ( = 0.05, P= 0.068). For the ACQ-treated wood, the final pH of the leachate from different leaching solutions was in the range of 5.37 (DI water) to 7.09 (LL). For the total Cu concentration from different leaching solutions, a trend of lower concentration with increasing pH was observed in most cases with the presence of organic matter also playing a role in a few observations (for e.g., WL-2 vs. WL-1). Statistically similar concentrations in ACQ leachate from DI and MHW waters were attributed to the formation of Cu(CO 3 ) 2 2and CuOH + around pH = 7 bringing more Cu in solution (Stumm and Morgan, 1996). On comparing the variability between different leaching solutions using single factor ANOVA analysis, the F-value was 217 and P-value was <0.01 indicating that the Cu concentrations leached in different natural waters were statistically significantly different ( = 0.05). On comparing individual means using the t-test, P = 0.041 ( = 0.05) for the means of ACQ WL-1 and ACQ WL-2 leachates, suggesting significant differences between Cu leaching in these two types of water. The CBA-treated wood leachate’s final pH varied from 5.54 (DI water) to 7.00 (landfill leachate). The highest Cu concentration (18.5 3.2 mg/L) was observed in the DI leachate of CBA-treated wood and the lowest concentration (12.3 1.5 mg/L) was observed in the lake water (LA). This followed the pH trend with higher leaching occurring at lower pH. Cu concentrations in other CBA leachates did not have much variation and were in the range 12.4 2.1 mg/L to 16.8 1.3 mg/L. On comparing the variability between different leaching solutions using single factor ANOVA analysis, the

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19 F-value was 6.93 and P-value was <0.01, indicating significant statistical differences among average concentrations measured in different types of waters ( = 0.05). Higher concentrations of Cu present in the CBA-treated wood blocks help drive the reaction towards more Cu leaching out in solution. Comparatively less variation in final pH among different leachates was also observed with CBA-treated wood leachates. This could possibly be one of the reasons for comparatively less variability among the Cu concentrations in different CBA leachates. The final pH of all three treated wood leachates with different leaching solutions was in the range of pH = 5 to pH = 8. In this pH range, Cu can exist in natural system as Cu-aq 2+ , inorganic complexes (CuCO 3 , CuOH + , Cu(CO 3 ) 2 , Cu(OH) 2 ), organic soluble complexes (fulvate) and colloids. Higher Cu concentration in CBA-treated wood samples also helped the ionic product of CuCO 3 0 (the most prominent species in the pH range encountered in these leaching tests, K sp = 10 -9.63 ) to exceed its solubility limit by comparatively higher amount compared to CCA-and ACQ-treated wood. Considering the total Cu present in the treated wood blocks, the percent Cu leached for CCA-treated wood was 0.3 to 1.5% for different leaching solutions. For the ACQand CBA-treated wood blocks, the percent leached for Cu varied from 2.2 to 6.7% and 4.4 to 7.7%, respectively, for different leaching solutions used in this study. In an earlier study using batch leaching tests on sawdust samples, the percentage of Cu leaching from CCA-, ACQand CBA-treated wood samples was found to be 6.4 to 19%, 14 to 40%, 19 to 39% respectively (Stook et al., 2005). Using the block samples in this study instead of sawdust as used by Stook et al. (2005) was one of the reasons for the lower percentage of the leaching of Cu from these treated wood products in the current study. Surface area

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20 plays a major role in the amount of preservative leached from treated wood products in a leaching test (Townsend et al., 2004). Kennedy and Colins (2001) used 19 mm blocks of CCA-and CBA-treated wood and leached them using AWPA E-11 methodology. The study found 4.9 to 6.5% and 8.9 to 9.2% of Cu leaching from CCA and CBA blocks at the end of 14 days of exposure period. The total Cu concentrations leached with the different leaching solutions for the three wood types were compared with parameters such as TDS, alkalinity, hardness, chloride, TOC, COD and turbidity of the leaching solution. As explained in the previous paragraphs, the combination of final extraction pH and the presence of inorganic and organic ligands in leaching solutions were found to impact the amount of Cu leaching from different leaching solutions with more Cu leached out in waters with higher concentrations of these ligands in most cases. The pH was found to be a more dominating factor for Cu leaching in some observations. 2.3.3 Labile Copper Concentration in Treated Wood Leachate The labile Cu concentration measured from different treated wood leachates produced on leaching with various leaching solutions is presented in Figure 2-4. For all three wood types, the highest labile Cu concentration was measured in the treated wood DI leachate. After calculating the percentage of Cu as labile compared to the total Cu measured in the treated wood leachate in natural waters, the labile Cu was found to vary from 0.3 to 2.4% for CCA, 0.5 to 2.5% for ACQ and 0.14 to 2.1% for CBA respectively. DI water leachate had 8%, 5% and 3% labile Cu for CCA, ACQ and CBA samples respectively. Ndungu et al. (2005) has found that only about 3% of total dissolved copper was labile in Cu-contaminated natural water samples in the San Francisco Bay area. When comparing the labile Cu concentrations with the leaching solution water

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21 quality parameter, the labile Cu concentration in the leachate sample was found to be inversely proportional to the TOC and alkalinity concentrations in the leaching solutions. The R 2 values between labile Cu concentrations and TOC in leaching solutions were 0.83, 0.72, and 0.98, respectively, for CCA, ACQ, and CBA. Similarly, for labile Cu and the alkalinity of the leaching solutions, R 2 values were 0.89, 0.73 and 0.95 respectively for CCA, ACQ, and CBA leachates. Figures have been included in Appendix A with labile Cu concentration vs. TOC and alkalinity of the water sample. This indicates that with higher concentrations of organic acids and inorganic ligands in solution, lower amounts of labile Cu would be available. 2.3.4 Aquatic Toxicity of Treated Wood Leachate Leachates from untreated southern yellow pine were found to be non-toxic to the MetPLATE test bacteria. The treated wood leachates all showed some degree of toxicity using MetPLATE. The results of all three treated wood samples leached with nine leaching solutions are summarized in Figure 2-5. Lower toxicity was observed with AO and LL leachate samples for each wood type (0.8 0.1 TU for LL-CCA and AO-CCA; 0.32 0.11 for LL-ACQ and 4.63 0.15 for AO-ACQ; and 1.20 0.13 for LL-CBA and 15.9 1.34 for AO-CBA) compared with the other leachates. This was attributed to the presence of inorganic (e.g., Cl , Br ) and organic ligands (e.g., CH 3 COO ) at comparatively higher concentrations in these leaching solutions making complexes with Cu and rendering it less bioavailable (Flemming and Trevors, 1989). The values corresponding to LL and AO leaching solutions are not included in Figure 2-5. Among the other nine leachates for each wood treatment, it was found that, in general, toxicity followed the pattern CBA > ACQ > CCA. For all three treated wood leachates the highest toxicity was observed from the DI leachate (CCA, 19.5 TU 3.7;

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22 ACQ, 92.8 TU 6.8; CBA, 649 TU 114), although as presented in Figure 2-1 through 2-3, the highest total copper concentration was observed from the treated wood leachate produced with LL as a leaching solution for CCA and ACQ samples. The highest total Cu leached and the highest toxicity was observed with DI water and the CBA sample. The higher toxicity with DI water could be attributed to lack of complexation due to the absence of any inorganic or organic ligands in this solution. When toxicity was compared to the labile Cu concentration as presented in Figure 2-4, a direct correlation was observed. The aquatic toxicity was also found to inversely correlate with TOC and alkalinity concentration of the leaching solution. The highest toxicity from ACQ-treated wood leachate (with DI water) was almost five times greater than the toxicity observed with CCA-treated wood leachate (again with DI water). This is not unexpected since ACQ-treated wood contains more Cu than CCA to start with and the percentage leaching of Cu from ACQ is also higher than that from CCA (Stook et al., 2004). 2.3.5 Comparison of Aquatic Toxicity with Leached Copper Concentrations Since copper was suspected to be the primary toxicant to the MetPLATE bacteria, the EC 50 values measured for all leachate samples were plotted as a function of their corresponding total copper concentrations (see Figure 2-6 through 2-8) for each treated wood sample to evaluate the proportion of aquatic toxicity due to Cu. For the purpose of comparison, the same scale was used for each axis in each plot. The figures illustrate in general that there was an increase in toxicity with an increase in Cu concentrations in most of the leachates. The toxicity value for Cu as EC 50 in mg/L was determined by conducting a MetPLATE toxicity assay on several dilutions of 1 ppm Cu as CuSO 4 . The EC 50 value obtained was 0.11 0.05 mg/L. Using this toxicity value

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23 for Cu, the toxicity was predicted using the different Cu concentrations as per the equation below. 100*mg/Lin Cu ofion Concentrat mg/Lin measuredCu 50,ECpredicted 50,EC % (3) The above equation has been adapted from the one used by Stook et al. (2004). Lines representing the range of toxicity expected to occur solely as a result of dissolved total copper (Cu +2 ) are plotted as dashed lines. These lines were created using the EC 50 values obtained from equation (3) as explained above. A majority of the EC 50 (%) and copper (mg/L) measurements fell within the range that would be expected from Cu +2 toxicity alone for the leachates in which no or low complexation ability was present . This indicates that toxicity was mainly due to Cu present in these leachates. For the other leachates, especially the ones from AO, LL and SJR, the EC 50 value was higher than would be expected from the total Cu concentration; this could be due to the fact that part of the Cu leached is not free and hence not available to affect bacterial activity. For the CCA-treated wood leachates from DI water and MHW and for the CBA-treated wood leachate from DI water and LA showed slightly higher toxicity than expected just from Cu alone, indicating that there are other chemicals in these leachates which are also contributing to aquatic toxicity. It is to be noted that a different set of bacteria was used when the aquatic toxicity assay was conducted for these samples than the one used for the 1 ppm Cu as CuSO 4 . This also could have contributed to the variability observed. Stook et al., (2004) has also used a similar approach of plotting the EC 50 (%) value along with Cu concentration in the leachate. While comparing the fraction of toxicity due to Cu alone in the two studies (Stook et al., (2004) and the present study), it was found that the observed toxicity from treated wood leachates followed the predicted

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24 values more closely in Stook et al. (2004). The leaching tests in that study were completed using various leaching fluids generated in laboratory. Since natural waters were used as the leaching fluid in the present study, the DOC and multiple inorganic and organic ligands present in natural water would complex with Cu (Cu makes stable soluble complex with various inorganic and organic ligands) and make it less bioavailable. The labile Cu concentration measured in this study essentially quantifies the free Cu and the loosely bound Cu present in treated wood leachate. As discussed in the previous sections, earlier studies have shown that this fraction of Cu does contribute to aquatic toxicity. When labile Cu concentration and the corresponding aquatic toxicity were plotted (presented in Figure 2-9), it was observed that there was a general trend of higher toxicity (lower EC 50 values) corresponding to higher labile Cu concentrations in the leachate. The regression analysis on the data presented in this figure gave a R 2 value of 0.34, 0.46 and 0.31 respectively for CCA, ACQ and CBA treated wood leachate. Figures 2-6 through 2-9, show a better correlation of toxicity with labile Cu concentration in the treated wood leachate compared to total Cu concentrations. 2.3.6 Heavy Metal Binding Capacity (HMBC) of Copper in Different Waters The highest HMBC values were observed for LL and AO waters for all three wood DI leachates (Figure 2-10). The HMBC values from different leaching solutions follow the trend of concentrations of TOC, COD and chloride in the solutions as presented in Table 2-1 with high HMBC values observed with high concentrations of these parameters in the leaching solutions. For CCA treated wood, the EC 50 (%) for LL and AO leaching solutions were higher than 100% and therefore the HMBC calculated using equation (2) was >5.62. One observation from Figure 2-10 is the difference in the binding capacity of Cu in different

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25 types of water was less pronounced for ACQ treated wood compared to CCA and CBA treated wood. The specific reason for this observation is not known. Ward et al., (2005) has conducted a HMBC study (using standard methodology as explained in the methods section) for Cu in LA water, the HMBC value obtained in the study was 1.1 0.1. For the Cu from three leachates, the HMBC value obtained for the LA water was 1.28 0.25, 1.32 0.17 and 1.26 0.12 for CCA, ACQ and CBA DI leachates, respectively. When HMBC values for different leaching solutions were compared with the toxicity of the treated wood leachates, a general trend of higher toxicity was observed in the leachates produced from a natural water sample which exhibited lower binding capacity of Cu. 2.4 Summary Total Cu concentrations in the leachates produced with various Florida surface water followed the trend CBA > ACQ > CCA. Higher Cu present in treated wood samples of Cu-based alternatives led to the release of higher Cu in the leaching solution. As mentioned previously, a higher percentage of Cu leaching was also observed with CBA and ACQ treated wood samples. Comparing the total Cu concentration with the drinking water (DW) limit (1.0 mg/L), all the leachate samples of ACQ and CBA exceeded the DW limit for total Cu. It should be noted that the leaching study reported in this chapter used an 80gm treated wood block with 1600mL of several FL surface waters as leaching solutions. In a natural water body large amounts of dilution would occur as the leached chemicals will get mixed with the surrounding water and will also be flushed with the new water flowing into the system. The Cu concentration measured in the leachates produced in this study would be expected to be higher than what would be measured in a natural system, but at the same time it gives an estimate of the impact of surface water chemistry on preservative leaching from treated wood products.

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26 The labile Cu concentration also followed the trend of total Cu with concentrations measured in the leachates as CBA > ACQ > CCA. None of the labile Cu concentration from any of the leachate samples exceeded the DW limit for Cu. Most of the surface waters in Florida are classified as Class III waters, which are categorized as “Recreation, Propagation and Maintenance of a Healthy, Well-Balanced Population of Fish and Wildlife” (FDEP 1996, 62-302.530). The Cu limits for Class III waters are 3.6-39 g/L (the range of the value is a function of water hardness with a range of 25mg/L – 400mg/L as CaCO 3 ) for predominantly fresh water and 2.9g/L for predominantly marine water. Comparing the labile Cu concentration with the Cu surface water criteria, it was found that for ACQ and CBA labile Cu concentrations were higher than the surface water limit of 39g/L. For CCA leachates the labile Cu concentrations exceeded the surface water limit (calculated with the assumption of a linear relation between hardness and Cu limit) in half of the samples. Toxicity values measured in different leachates followed the trend CBA > ACQ > CCA. A similar trend was observed by Stook et al. (2004). Labile Cu concentration correlated with the toxicity values as R 2 = 0.64 (CCA), 0.75 (ACQ) and 0.69 (CBA). In general lower toxicity was observed with lower labile Cu concentration in the leachate. Labile Cu concentration was found to correlate with the water chemistry of the leaching solutions. Toxicity was reduced in the treated wood leachates with natural waters compared to DI and MHW. This is believed to be due to the presence of inorganic and organic ligands in the natural waters. The Cu binding capacity was found to be relatively similar for receiving waters when leachates from three different Cu treated wood samples were spiked to the natural water. Treated wood leachate with natural water as leaching

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27 solutions exhibited higher toxicity for the water showing lower binding capacity for Cu in the HMBC study.

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28 Table 2-1 Characterization of leaching solutions for water quality parameters Leaching Solution pH TDS (mg/L) Alkalinity (mg/L as CaCO 3 ) Hardness (mg/L as CaCO 3 ) Chloride (mg/L) TOC (mg/L) COD (mg/L) Turbidity (NTU) Cu (g/L) DI 6.44 <10 <1 <1 <10 <10 <10 0.2 <4.0 MHW 7.74 150 57 94 <10 26 23 0.2 <4.0 KR 6.39 90 17 25 26 32 41 0.94 <4.0 SJR 7.98 820 59 116 36 41 47 1.78 <4.0 LO 7.35 165 54 59 22 43 62 1.96 <4.0 LA 7.24 160 107 90 <10 49 30 1.64 13.0 LW 7.28 360 97 73 17 110 75 2.58 <4.0 WL-1 6.98 940 37 44 27 173 140 4.31 11.0 WL-2 6.59 185 27 12 <10 57 41 1.45 35.0 AO 8.14 39,000 250 2,080 >15,000 21 960 0.29 <4.0 LL 7.12 8,760 4,800 438 2,380 450 1,200 44.4 20.0 Extraction solutions DIMHWKRSJRLOLALWWL-1WL-2AOLL Copper concentration (mg/L) 0.00.20.40.60.81.01.2 CCA4.836.957.396.725.746.377.156.606.016.276.15 Figure 2-1 Total copper leaching from CCA treated wood products in different leaching solutions (error bars represent standard deviation of four replicates, the final pH of the extraction solutions is presented within the bars)

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29 Extraction solutions DIMHWKRSJRLOLALWWL-1WL-2AOLL Copper concentration (mg/L) 024681012 ACQ5.377.006.026.806.826.847.096.846.676.376.32 Figure 2-2 Total copper leaching from ACQ treated wood products in different leaching solutions (error bars represent standard deviation of four replicates, the final pH of the extraction solutions is presented within the bars) Extraction solutions DIMHWKRSJRLOLALWWL-1WL-2AOLL Copper concentration (mg/L) 0510152025 CBA5.546.796.076.806.596.887.006.646.486.476.43 Figure 2-3 Total copper leaching from CBA treated wood products in different leaching solutions (error bars represent standard deviation of four replicates, the final pH of the extraction solutions is presented within the bars)

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30 CCAExtraction solutions DIMHWKRSJRLOLALWWL-1WL-2 Labile Cu (g/L) 010203040 ACQExtraction solutions DIMHWKRSJRLOLALWWL-1WL-2 Labile Cu (g/L) 050100150200250 CBAExtraction solutions DIMHWKRSJRLOLALWWL-1WL-2 Labile Cu (g/L) 0200400600800 Figure 2-4 Labile copper concentration in the treated wood leachate (error bars represent standard deviation of four replicates)

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31 CCA DIMHWKRSJRLOLALWWL-1WL-2 Toxicity Unit (TU) 110100 ACQ DIMHWKRSJRLOLALWWL-1WL-2 Toxicity Unit (TU) 10100 CBA DIMHWKRSJRLOLALWWL-1WL-2 Toxicity Unit (TU) 101001000 Figure 2-5 MetPLATE toxicity of treated wood leachates as a function of leaching solution (error bars represent standard deviation of four replicates).

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32 DI MHW KR SJR LO LA LW WL-1 WL-2 AO LL Copper (mg/L) 0.1110100 EC50(%) 0.1110100 CCA EC50 Cu = 0.11.05mg/L Figure 2-6 Total copper concentrations (mg/L) vs. toxicity EC 50 for CCA-treated wood leachates (The dotted lines indicate the range of toxicity predicted due to total Cu alone) ACQCopper (mg/L) 0.1110100 EC50 (%) 0.1110100 DI MHW KR SJR LO LA LW WL-1 WL-2 AO LL EC50 Cu = 0.110.05mg/L Figure 2-7 Total copper concentrations (mg/L) vs. toxicity EC 50 for ACQ-treated wood leachates (The dotted lines indicate the range of toxicity predicted due to total Cu alone)

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33 EC50 Cu = 0.11.05mg/L Copper (mg/L) 0.1110100 EC50(%) 0.1110100 CBADI MHW KR SJR LO LA LW WL-1 WL-2 AO LL EC50 Cu = 0.110.05mg/L Figure 2-8 Total copper concentrations (mg/L) vs. toxicity EC 50 for CBA-treated wood leachates (The dotted lines indicate the range of toxicity predicted due to total Cu alone)

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34 CCALabile Cu Concentration (mg/L) 0.0010.010.1 EC50 of Leachate (%) 110100 R2=0.64 ACQLabile Cu Concentration (mg/L) 0.010.11 EC50 of Leachates 0.1110 R2=0.75 CBALabile Cu Concentration (mg/L) 0.010.11 EC50 of Leachate 0.1110 R2=0.69 Figure 2-9 Labile copper concentrations (mg/L) vs. toxicity EC 50 for treated wood leachates

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35 CCA KRLOSJRLALWWL-1WL-2AOLL Copper binding capacity 0123456 >5.62Extraction solutions ACQ KRLOSJRLALWWL-1WL-2AOLL Copper binding capacity 01234567 Extraction solutions CBA KRLOSJRLALWWL-1WL-2AOLL Copper binding capacity 0246810 Extraction solutions Figure 2-10 Copper binding capacity of different extraction solutions when copper was spiked to natural waters. Spike was made by leaching treated wood with DI water (error bars represent standard deviation of three replicates)

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CHAPTER 3 COMPARISON OF RELATIVE RISKS FROM PRESERVATIVE COMPONENTS IN SOIL BELOW STRUCTURES MADE OF CCA, ACQ, CBA AND DOT TREATED WOOD 3.1 Introduction Concerns over the human health and environmental impact of chromated copper arsenate (CCA) treated wood structures caused the treated wood industry to voluntarily withdraw CCA-treated wood from most residential applications starting in 2004 (EPA, 2002). One of the concerns was leaching of preservative components, especially arsenic, (As) from treated wood structures into underlying soil. The risks include elevation of surface soil concentration and possible direct human exposure (e.g. inhalation, dermal contact, ingestion), and also the contamination of groundwater due to preservative leaching from the treated wood structure through the soil into the groundwater. In general, direct exposure is evaluated by considering the total concentration of pollutants (mg/kg) in the waste and evaluating the risk based on assumptions of the mass of waste entering the body and the toxicity of the pollutants of concern. For the risk of contaminating groundwater from a pollutant, a common approach is to conduct a leaching test. A similar approach was used in this study as explained subsequently in this chapter. New preservatives containing copper (Cu), boron (B) and organic biocides are now marketed as replacements to CCA. Although substantial research has been reported regarding preservative leaching from CCA-treated wood and its impact on the surrounding soil environment (Stillwell and Gorny, 1997; Lebow et al., 1999; Stillwell 36

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37 and Graetz, 2001; Kennedy and Collins, 2001; Lebow et al., 2003; Townsend et al., 2003a; Dagan et al., 2006), little similar research has been reported for the CCA replacements. A previous study (Stook et al., 2005) examined the relative risks using the batch leaching tests on CCA and various Cu based alternatives under different environmental scenarios. The percentage of preservative leaching in the batch leaching test of synthetic precipitation leaching procedure (SPLP) was calculated and used to estimate the soil concentration that might result if wood preservative chemicals leached from a treated wood structure in a similar fashion as measured using SPLP. The estimated preservative component concentrations were compared with the risk-based soil cleanup target levels (SCTLs) and risk factors were calculated for each chemical. Comparing the risk factors for various chemicals in several wood preservatives, it was concluded that CCA-treated wood posed a greater problem with respect to soil contamination. The above risk calculations were done using the data calculated by laboratory batch leaching tests. Various factors including pattern of rainfall, exposure of the structure to UV, temperature, and humidity, among others, would influence the rate of preservative leaching from a treated wood structure exposed to natural conditions. These factors are generally not considered in a standard batch leaching test. Additionally, there have been criticisms of batch leaching tests for over-predicting the chemical concentrations in the leachate compared to that encountered under natural conditions. The objective of this study was to compare the relative risk of treated wood products based upon data collected from more realistic field tests. Small scale decks were constructed and exposed to natural precipitation. After each rain event, runoff from

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38 the decks were collected and analyzed for preservative components. Part of the runoff was passed through the soil columns and the effluents from each soil column were analyzed for preservative components. At the end of the experiment, preservative concentrations were measured in the top surface layer (5 cm) in soil columns. Risks from direct exposure and potential groundwater contamination from preservative chemicals was assessed using the concentrations measured with the deck runoff and soil column eluent and surface soil samples generated in the present experiment. 3.2 Material and Methods 3.2.1 Construction and Setup of Decks Pressure treated wood lumber (CCA, ACQ and CBA) was purchased from Central Builders Supply in Gainesville, Florida. The borate treated wood was purchased from a wood treatment company (Cook Lumber) in Tampa, Florida. Two different sizes of lumber 5cm 15cm (2" 6") and 10cm 10cm (4" 4") were used for deck construction. It is to be noted that the nomenclature for lumber sizes used does not represent the exact size of the wood piece (for example, 4" 4" dimensional lumber will not measure 4" 4"for its cross-section). The deck was 1.2m 1.2m (4' 4') in plan and 0.9m (35”) in height. The plan and sectional view along with additional construction details of the decks are included in Appendix B. The tub in which the decks were placed was 1.3m 1.3m (52"") in width with a depth of 0.9m (35”). A total of five decks were set up, one each made of wood treated with CCA-, ACQ-, CBA-, and DOT-treated wood. An untreated wood deck was also included in the study as a control. The water hitting the deck and collected at the tub bottom were collected in jars. The jars were covered with a box to avoid exposure to sunlight. The whole assembly was kept at an angle of approximately 5 to facilitate runoff collection at the bottom.

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39 3.2.2 Soil Collection and Characterization Three different soil horizons were used in the soil column study. These soils were collected from a research site at Citra, Florida (see Figure 3-1); this site was recommended by University of Florida soil scientists. The soil samples were characterized for their physical and chemical properties. The pH was measured using the EPA Method 9045C (EPA, 2003). Moisture content on the soil sample was measured by drying several grams of sample in an oven overnight at 105 o C and the weight loss was quantified as the moisture content of the soil (ASTM D 4959-89). Bulk density was measured by filling a 100mL graduated cylinder with the soil sample; the soil was filled in as different layers and compacted lightly between the layers. The weight of the soil required to fill in 100mL was recorded and was used for bulk density determination. The measure of organic carbon in the soils was obtained through following the Walkley-Black Method as described in the USDA Soil Survey Methods Manual (USDA, 1992). The amorphous Fe and Al concentrations in the soil samples were obtained by acid oxalate ammonium extraction (in the dark). The method used was essentially a modification of the McKeague and Day procedure (McKeague and Day, 1966). 0.25gm of soil sample (for sandy soil 2 grams) ground to pass through a 2.5 mm sieve was taken in a 15mL disposable test tube, and 10mL of acid oxalate solution (mixture of ammonium oxalate and oxalic acid, adjusted to a pH of 3) was added. The soil was extracted in the solution for four hours in the dark. After the extraction, the soil solution was centrifuged at 2000 rpm for 20 minutes. The clear supernatant was analyzed by ICP-AES (Thermo Jarrell Ash Corp. Trace Analyzer) by EPA Method 6010B for Fe and Al. Particle size distribution of the soil sample was carried out as per the Soil Survey Staff Method (USDA-NRCS, 1996). The effective cation exchange capacity (CEC e ) of

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40 soil samples was determined using a 0.2 M NH 4 Cl extraction solution. Five grams of soil sample were taken in a 50-mL centrifuge tube; 30mL of 0.2 M NH 4 Cl was added and vibrated at the speed of 260 rpm for 5 minutes. The extracted solution was centrifuged at 4000rpm for 10 minutes and the supernatant was collected in a 250mL flask. The extraction and centrifugation step were repeated three more times. Combined supernatants were diluted to 250mL using the 0.2 M NH 4 Cl solution and were analyzed using ICP-AES as per EPA Method 6010B (EPA, 2003) for Na, K, Ca, Mg and Al. The CEC e from each of these elements were calculated and added to get the total CEC e . The total metal concentrations (mg/kg) were obtained by conducting an acid digestion following EPA method 3050B prior to analyzing the samples on ICP-AES using EPA method 6010B. The taxonomy of soil used in the study was Loamy Siliceous Hyperthermic Grossarenic Paleudult. The soil series and order for the soils used was SPARR and Ultisols, respectively. Table 3-1 presents the different physical and chemical properties of the soil samples used in the study. The pH for the three soils was in the range of 5.81 to 6.66. The texture class of a soil sample was measured by obtaining relative fractions of sand, silt and clay. As the texture of soil material became finer, the groundwater velocity tend to decrease for the same groundwater potential. For example, a coarse-textured sandy soil provides good drainage when not overlain by fine grained clay. Such coarse grain material will lead to contaminant migration. In addition, as soil texture becomes finer and clay content increases, grain surface area increases, which increases the soil sorption capacity. For the three soil horizons included in the present study, as observed from the particle size analysis results, organic and sandy horizons are

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41 essentially “sand” as per USDA classification and clay horizon is “sandy clay loam”. Therefore, for the columns containing soil from the clay horizon, a higher sorption capacity would be expected for heavy metals. The total metal concentrations of As, Cr, Cu and B from the three soil horizons are also included in Table 3.1. The average As concentrations for the three soil horizons are 2.8 mg/kg, 3.4 mg/kg and 6.2 mg/kg for organic, sandy and clay horizons respectively. When compared to the study by Ma et al. (Ma et al., 1997) on concentrations and distribution of eleven metals in Florida soils, it was found that the values obtained for As, Cu and Cr concentrations in the present study are in the same order of magnitude as reported (geometric mean) in the literature (Ma et al., 1997) but were at slightly lower levels. 3.2.3 Soil Column Construction and Set up Soil columns were constructed using a 5 cm diameter (2 inch) PVC pipe. Each column was 76 cm (30 inches) long. A reducer was glued at the bottom of the pipe to accommodate a 2.5cm (one inch) valve used for leachate sample collection. The top of the column was capped with a 5cm (2 inch) cap; a hole was made in the cap to facilitate the deck runoff addition using a tube (Figure 3-2). A geotextile was placed at the bottom of the column. Fifteen centimeters (six inches) of drainage layer (pre-washed pea gravel) was placed on top of geo-textile. 45cm (18 inches) of soil was placed on top of the drainage layer,. The soil was placed in six lifts of 7.5 cm (3inches) each. In between the lifts, the soil was lightly compacted for even distribution of soil. The soil layer was separated from the gravel layers at the top and bottom by using a stainless steel screen. A pea gravel layer of 7.5cm (3 inches) was added on top of the screen to facilitate even distribution of deck runoff into the soil columns.

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42 Three soil columns were set up for each deck runoff, each column having a different soil horizon, making a total of fifteen soil columns. Part of the deck runoff collected after every rain event was passed through the soil column. The cross-sectional area of the deck and of the soil column was calculated. It was found that the soil column had 0.14% of the area of the deck. A factor of 10 was applied and 1.4% of runoff collected from a deck in the field was passed through the corresponding soil columns using a peristaltic pump at a rate of 2mL/min. During the latter part of the experiment 5% of the deck runoff collected in the field was passed through the soil column. The effluent from the soil columns were collected at regular intervals and analyzed for preservative components. 3.2.4 Leachate Analysis The deck runoff and eluent coming off the soil column were analyzed for preservative components. The samples were digested using EPA Method 3010B (EPA, 2003) and digestates were analyzed on an ICP-AES by EPA Method 6010B for As, Cr, Cu and B. The ICP detection limits for As, Cr, Cu and B were 12g/L, 4g/L, 4g/L and 6g/L, respectively. The runoff from the deck and soil column eluents were also analyzed for organic biocide content, such as DDAC concentration in ACQ and tebuconazole concentration in the CBA deck runoff and soil column eluents. The method for DDAC determination was adapted from a procedure developed by Chemical Specialties Incorporated, Charlotte, NC. The method is a two-phase titration using the leaching fluid as one phase and chloroform as the second phase along with an indicator dye (methylene blue). The method is based on DDAC being a cationic surfactant, and sodium dodecyl sulfate is an anionic surfactant. An aqueous sample containing DDAC and methylene blue is placed into a container with chloroform. Two

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43 distinct phases are seen. There is a blue aqueous layer containing the DDAC and a clear chloroform layer. The sample is then titrated with sodium dodecyl sulfate (SDS). SDS forms a more stable complex with DDAC and the indicator dye is displaced into the chloroform layer, which turns blue (AWPA, 1999). The detailed analytical procedure is presented in Appendix B. Tebuconazole analysis method was an AWPA (2000) standard method to determine the concentration of tebuconazole in treated wood leachates. The method as published is for extraction and analysis using gas chromatography with a nitrogen phosphorus detector (GC-NPD), but the samples from this study were analyzed using gas chromatography coupled with a Flame ionization detector (GC-FID). The leachate samples were saturated with sodium chloride, extracted with methylene chloride and concentrated prior to analysis on the GC-FID. Appropriate spikes and blanks were included in all analyses. Detailed analysis steps have been described in Appendix B. 3.2.5 Dismantling of Soil Columns and Surface Soil Analysis At the end of the experiment, the soil columns were dismantled. The top 5cm of soil was collected for each column. The collected soil was dried overnight at 105C and analyzed for total metal content by digesting 2gm of soil sample in triplicates following EPA Method 3050B. The digestates were analyzed using ICP-AES following EPA Method 6010B. Concentrations of organic biocides in the surface soil samples were calculated using a mass balance approach. It was assumed that all the organic biocide is concentrated in the top 5cm of the soil column. The total concentration added to the soil column (calculated from organic concentration in deck runoff and the volume of runoff added to the soil column) was obtained and was subtracted by the total organic biocide

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44 concentration in the soil column eluents. The balance was assumed to be distributed evenly in the top 5cm of soil column. 3.2.6 Calculation for the Percent Mobility and Relative Risk in Soils The percent mobility for a particular preservative was calculated as the ratio of the corresponding cumulative soil column eluent concentration divided by the cumulative amount of that particular preservative added to the soil column as presented in equation (1) below. column soil toaddedion concentrat vepreservati Cumulativeionconcentrateluent column soil CumulativeMobility% (1) The relative risk factor for a preservative component in soil was calculated for different soil types as per the approach used by Townsend et al. (2003c). The risk factor for a chemical “x” is the ratio of soil sample concentration divided by the Florida Soil cleanup target levels (SCTLs) limits for that particular chemical as presented in the equation below: xSx,SCTLx,SCTLCRF (2) Where, RF x, SCTL = risk factor, C x,s = concentration of chemical in surface soil, and SCTL x = SCTL of chemical “x”. 3.2.7 Calculation of SCTL and GWCTL for Organic Biocides The available toxicological data has been reviewed for both DDAC and tebuconazole and has been summarized in Table B-1 of Appendix B. DDAC and tebuconazole SCTLs for ingestion route as well as groundwater cleanup target level (GWCTLs) were calculated by using corresponding non-carcinogen risk-based equations from Saranko et al. (1999). The available chronic toxicity data on dog (NOEL = 10

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45 mg/Kg-day for DDAC and 2.96 mg/kg-day for Tebuconazole) was used for the oral reference dose calculation which was calculated using an uncertainty factor of 100 (personal communication Dr. Steve Roberts, University of Florida). A detailed stepwise calculation is presented in Appendix B. 3.3 Results and Discussion 3.3.1 Deck Runoff Characterization The treated wood decks were exposed to a rainfall of 17.2cm (6.75 inches) throughout the experimental duration of 155 days. As mentioned previously, deck runoff was collected after each rain event throughout the experimental duration. The runoff samples collected were analyzed for preservative components. Figures 3-3 to 3-6 present the Cu, B, DDAC, tebuconazole, As, and Cr concentrations of the deck runoff from CCA, ACQ, CBA, and DOT decks. In general, the concentrations of the preservative elements evaluated decreased as more runoff volumes were collected with the progress of the experiment with a higher rate during the initial part of the experiment. This observation suggests a “wash off” from the surface of the wood. On occasion an increase in concentration was observed (e.g., between cumulative runoff of 100 to 150 liters). This increase could be due to alternate drying and wetting of the deck surface in between the sampling events. When the wood surface dries, the moisture inside the wood could move towards the surface and with this moisture movement preservatives would also make their way towards the surface of the wood and be available for leaching. Khan (2004) also found higher concentrations of As in subsequent runoff samples after a dry period of several days and hypothesized that the releases were associated with splitting of the wood and possibly effects from ultraviolet light. Other factors such as the intensity and pattern of rainfall also affect the leaching rate of preservative components. Cockcroft and

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46 Laidlaw (1978) found more leaching of preservatives when rainfall was light but for a longer duration compared to a heavy downpour for a short period of time. The higher rate of Cu leaching from ACQ and CBA samples compared to CCA has been observed. Stook et al. (2004 and 2005) also found a higher percentage of leaching of Cu with ACQ and CBA samples in batch leaching experiments as compared to CCA. It was hypothesized as a result of the absence of Cr, which partly oxidizes the lignocellulose material to provide relatively strong binding sites for Cu in CCA-treated wood (Schultz and Nicholas, 2003). Boron concentrations in the DOT leachate were reduced to one-third of its initial value after the first three rain exposures (50 L of runoff). ACQ and CBA deck runoff samples had lower B concentrations when compared to DOT and the rate of leaching was also relatively uniform when compared to DOT-treated wood. Cumulative Cu in the runoff samples of the CCA, ACQ and CBA decks were 65.6 mg, 700mg, and 670mg, respectively. Cumulative B concentrations in the runoff were 305mg, 334mg and 2056 mg for ACQ, CBA and DOT decks respectively. The variation of cumulative preservative components leaching as a function of cumulative deck runoff has been presented in Appendix B. Results also show that 0.8%, 0.7% and 1.5% of total B leached out from ACQ, CBA and DOT decks, respectively. As observed in a previous study (Humar et al., 2004) comparatively higher percentages of B leached from borate treated wood compared to ACQ treated wood. Cumulative As and Cr loss in deck runoff was 212mg and 56 mg, respectively. Results also showed that 0.1% of the As leached and 0.03% of the Cr leached during the duration of the experiment.

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47 After the 71 st day of the experiment’s duration, the concentrations of DDAC and tebuconazole were below detection (<0.1mg/L) in the deck runoff samples (Figure 3-5). Cumulative losses for DDAC and CBA samples were 17.1mg (0.005%) and 20 mg (0.09%) respectively. The deck runoff from the untreated wood deck and the rain water samples were also analyzed periodically for As, Cu, Cr, B, DDAC and tebuconazole; the concentrations were consistently below the detection limits of the concerned analytical method. 3.3.2 Preservative Concentrations in the Soil Leachate Figure 3-7 through 3-9 presents the Cu, B, As and Cr concentrations from different soil columns as a function of cumulative soil column eluent volume. The concentrations of these elements in the eluent from three different soil types followed a similar trend. As explained in the methodology section during the initial part of the experiment, 1.4% of the deck runoff was passed through the soil column. During this phase (approximately up to 2000mL of eluent volume) there was a steady increase in the eluent Cu concentration over time. During the next phase when a higher volume (5%) of deck runoff was passed through the soil columns, there was a considerable elevation of Cu concentration in the soil column eluent. The change was more pronounced in the ACQ and CBA soil column eluents than in the CCA eluent, as the influent to the soil column from ACQ and CBA had much higher Cu concentrations compared to CCA. This phase simulated a scenario of heavy storm flooding. None of the soil eluents exceeded the drinking water limit for Cu of 1.0 mg/L for the duration of the experiment. For the DOT sandy and organic soil columns B concentration exceeded its groundwater cleanup target level of 630g/L during the second half of the experiment. Boron concentrations in the soil column eluent of organic and clay horizon sample followed an identical trend. The

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48 same trend was not observed for sandy soil. The comparatively lower pH and lower OM content may have influenced this phenomenon as explained in the next section. The highest B cumulative concentration was observed in the deck runoff from DOTtreated wood, hence the highest cumulative B concentration for the three soil types was also observed in the soil column which received the runoff from the DOT deck. The difference in the cumulative B concentration among DOT-, ACQand CBA-treated wood columns was reduced with the three soil types. The highest difference was observed with the sandy soil which had the lowest retention for B (see Table 3-2). As the mobility of B increased with the other soil types, the difference between the ACQ and CBA cumulative concentration and DOT cumulative concentration were reduced over time. Figure 3-9 presents the As and Cr concentrations as a function of soil column eluent volume. As and Cr followed a similar trend as Cu and B. The Cr concentrations in the soil column eluents never exceeded the drinking water limit of 100g/L throughout the duration of the experiment. The As concentration of the soil column eluents exceeded the new drinking water standard of 10g/L from the very first sample and it exceeded the existing drinking water standard of 50g/L during the second half of the experimental duration of 155 days. DDAC and tebuconazole concentrations were below detection limits for all the ACQ and CBA leachates respectively throughout the duration of the experiment. This suggest that the organic biocides added to the soil columns as part of ACQ and CBA runoff were either adsorbed in the soil column or were degraded while passing through the soil column. A previous study has shown that more than 90% of DDAC in a river was bound with the sediments (Environmental Canada, 1999). A similar situation could

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49 explain the results from the current study, where the organic co-biocides associated with ACQ & CBA were bound to sediments in the soil column. 3.3.3 Mobility of Preservative Components in Different Soils The percentage of mobility of all the preservative components is presented in Table 3-2. Similar mobility was observed for Cu from CCA, ACQ and CBA samples. Chromium from CCA showed the highest percent mobility among all the elements. Boron from ACQ, CBA and DOT samples exhibited similar percent mobility. The same amount of preservative components was added to the three different soil horizons as part of column influent. Comparing the percente mobility (the inverse of the fraction retained in the soil) for the three soil horizons, the highest amount of Cu was retained with clay soil followed by organic soil with sandy soil retaining the least amount of Cu among the three. The factors which influence the mobility of Cu in soil are pH, OM, oxides of iron and manganese and the soil type (% clay and silt) (Adriano, 2001). Copper mobility is highly reduced above pH 7 and for pH < 7, the lower the pH, the higher the mobility. For the three soil types used in this experiment, sandy soil had the lowest pH of 5.81which could be the reason for lower retention of Cu in sandy soil columns. The organic soil horizon used in this study is also classified as a sandy soil (as per USDA classification), but this soil has comparatively higher OM than the other two (nearly 5 times). Copper makes a very strong complex with OM which could have helped in reducing Cu mobility in the organic horizon soil columns (Tyler and McBride, 1982). Soil texture, particularly the silt and clay fractions, have been positively correlated with sorption capacity of soil for Cu (Dhillon et al., 1981). The higher silt and clay fraction in the clay horizon soil helped to achieve lower mobility for Cu in those columns. Similar mobility with Cu was

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50 also observed by Dagan et al. (2006) while evaluating the metal attenuation capability of three different soil types using laboratory generated CCA-treated wood leachate. The Cu mobility in ACQ and CBA soil columns also followed a similar trend with the lowest mobility in clay horizon and the highest in sandy horizon, indicating that Cu from all three treated wood types would behave similarly in soil environments. Boron mobility in soil is also influenced by soil pH, OM, clay content, and iron and aluminum oxide content in the soil (Adriano, 2001). In the pH range of 5.4 to 7.5 (all three soils evaluated in this chapter were in this range) the mobility is uniform (Parker and Gardner, 1982). As in the case of Cu, here again higher mobility was observed in sandy soil, followed by organic and clay soil. High amounts of amorphous iron and aluminum and higher clay content in clay soil horizon enhanced the absorption of B in these soils for all treated wood types (Adriano, 2001). In soils with comparatively lower pH, OM plays a major role in B absorption by forming stable complexes. The highest As and Cr concentrations were retained in sandy horizon columns and the lowest in the clay horizon columns. As and Cr exist as oxyanions in the soil solutions. Iron and aluminum oxide present in the soil form a bridge between soil organic matter and oxyanions by forming a coordination bond (Chirenje et al., 2003). A positive correlation has been established between amorphous iron and aluminum concentration and arsenic retention in soil (Cai et al., 2002). The clay horizon soil used in this experiment had the highest amorphous iron and aluminum and hence the lowest mobility of As and Cr. Adsorption of As decreases with increasing pH (Smith et al., 1999). In the present study the sandy soil had the lowest pH and also the lowest retention of As.

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51 3.3.4 Concentration of Preservative Components in the Surface Layer of Soil Column At the end of the experiment, the top surface layer of the soil columns (5cm) was analyzed for Cu, B, As and Cr. The content of DDAC and tebuconazole in the top surface was calculated using a mass balance approach as explained in the methods section of this chapter. The concentration of different preservative components has been presented in Table 3-3. In general, higher concentrations of these components were found in the clay surface soil samples compared to the other two soil surface samples. Concentrations followed the trend: clay horizon > sandy horizon > organic horizon for most of the samples. It should be noted here that the organic and the sandy horizons were classified as sandy soils as per USDA classification (detail presented in section 3.2.2). The percentage of mobility values (see Table 3-2) for an element in different soils follows the same trend as the soil concentrations measured in surface soil samples, with higher concentration measured in soil with a lower percentage of mobility. When the concentration measured in the present study was compared with the values available in literature, it was found that the average As, Cr and Cu concentrations measured in the surface soil samples of this study were lower than the average values measured from the soil samples collected below the CCA-treated wood deck by Townsend et al. (2003a) and Stillwell and Gorny (1997). The As concentration in all three soil types exceeded the risk-based Florida SCTL residential limit. Clay horizon surface soil exceeded the limit by a factor of 8.7 followed by sandy horizon (3.5) and organic horizon (2.0). No other elements exceeded the SCTL limit in any of the samples. The concentration of organic components was calculated based on a conservative assumption that all the DDAC and tebuconazole concentrations added to the column were

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52 adsorbed to soil and retained in the top 5 cm layer of soil columns. The calculated value for DDAC and tebuconazole is included in Table 3-3. The concentration for both the organic chemicals followed the trend of organic horizon > clay horizon >sandy horizon. Comparing the two organic chemicals among themselves, the concentrations were similar for the different soil types. 3.3.5 Relative Risk Assessment for Preservative Components of Different Treated Wood Risk factors, as defined in section 3.2.5, were calculated for each component in the different soil types as presented in Table 3-4. The risk factor for different preservative components for sandy horizon surface concentrations is also presented as Figure 3-10. The risk factor is the ratio of soil sample concentration divided by the Florida Soil cleanup target levels (SCTLs) limits (FDEP, 2005). Arsenic from CCA treated wood exceeded the SCTL for residential settings for all three soil horizons and also for the industrial setting in the clay horizon soil samples. Other than As, no components exceeded the SCTL limits for the concentrations observed in this experiment. When comparing the risk factors for Cu in different wood treatments, Cu from ACQ and CBA has eight to ten times more chances of exceeding SCTL for Cu compared to that from CCA-treated wood. Similarly the chances of exceeding the SCTLs for B is six to eight times higher for DOT treated wood compared to ACQ and CBA. Chromium concentrations did not exceed SCTL limits in this experiment. Comparing the various risk factor values presented in Table 3-4, it was found that for most of the components (except As) the concentrations were very low, and not to exceed the SCTL industrial limits of these chemicals. For the residential limits, Cu concentration in ACQ and CBA soil columns were approximately 70%, 40% and 30% of the residential limit in clay,

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53 sandy and organic horizons, respectively. Arsenic from CCA-treated wood was most likely to exceed SCTLs. Soil Cleanup target levels for the ingestion route were calculated for DDAC and tebuconazole as per the methodology presented in section 3.2.6. The values obtained were 21.4mg/kg for DDAC and 6.4 mg/kg for tebuconazole. The maximum concentration calculated from the mass balance approach in the surface layer (5 cm) was 2.9mg/kg for DDAC and 2.87 mg/kg for tebuconazole as presented in Table 3-3. The ratio of maximum soil concentration with corresponding SCTL values were 0.14 and 0.45 for DDAC and tebuconazole respectively. Comparing the relative risk from organic biocides with the inorganic components of ACQ and CBA, it was found that risk from these components follow the order Cu > organic biocide > B. A GWCTL limit for DDAC and tebuconazole were also calculated as per the procedure outlined in 3.2.6 and was found to be 0.7mg/L and 0.21 mg/L respectively. Figure 3-11 presents the relative risk factors for potential groundwater contamination from preservative components using the maximum concentration observed in the soil column eluent of the sandy soil column. Boron from DOT-treated wood was found to have the highest relative risk factor followed by As from CCA-treated wood. When the relative risk factor was calculated using the deck runoff concentrations (Figure 3-12), B from DOT and As from CCA-treated wood were found to have higher relative risk factors compared to risks from Cu and organic biocides from ACQand CBA-treated wood. For ACQand CBA-treated wood, Cu was found to have higher relative risk compared to organic biocides.

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54 3.4. Summary In this experiment the risk from preservative components in the deck runoff, soil column eluents, and the concentration in surface soil samples were compared for different wood preservations and soil types. Among the deck runoff samples, Cu concentration in ACQ and CBA samples were higher than the GWCTL for Cu (1mg/L) for most of the experiment. Copper concentrations in the CCA deck runoff samples were approximately at 10% of the concentrations measured from CBAand ACQ-treated wood. Boron concentrations were higher than the corresponding GWCTL of 630g/L for CBA samples throughout the duration of the experiment and for ACQ during the first half of the experiment. Copper concentrations in the deck runoff samples of ACQ and CBA were statistically similar. The DOT deck leached approximately 10 times more B than the CBA and ACQ samples. For the CCA deck samples As and Cr concentrations were higher than the DW limits of 50g/L and 0.1mg/L, respectively, for the duration of the experiment. The highest concentration of DDAC measured in the ACQ runoff sample was 0.24 mg/L. DDAC does not have a GWCTL as of date. The maximum concentration measured in the deck runoff was 3.4% of the calculated GWCTL for DDAC. Similarly the highest tebuconazole concentration in the CBA deck runoff sample was 0.32mg/L, and was 15.5% of the calculated GWCTL. Therefore, in terms of deck runoff samples, a higher risk was observed from Cu and B in CBA and ACQ samples, and As and Cr had comparatively higher risk for CCA samples. Boron leaching was limiting for the DOT treated wood decks. Among the soil column eluent samples, Cu concentration in all the samples was below the GWCTL limit for Cu. Comparatively, Cu concentrations were higher in the

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55 ACQ and CBA columns compared to the CCA columns. Boron concentration in the sandy soil column eluents of DOT samples exceeded the corresponding GWCTL for B during the second half of the experiment. Arsenic concentration in the soil column eluents exceeded the new DW standard of 10g/L for most of the samples. DDAC and tebuconazole were below the detection limit (<0.1mg/L) for all the soil column eluents of ACQ and CBA samples respectively. Comparing the relative risk in terms of preservative chemical concentrations in the soil column eluent, a higher risk was observed with As concentration in CCA soil column (in all soil types) eluents and boron concentration in DOT sandy soil column eluents. Most of the Cu was absorbed in soil resulting in relatively low risk from Cu. Comparing the risk factors (as presented in detail in the previous section) for different elements under different wood preservation and soil types, it was found that ACQ and CBA have almost a ten times higher chance of exceeding SCTL for Cu compared to CCA. A similar observation was made for B in DOT treated wood compared to ACQ and CBA. For organic components of DDAC and tebuconazole, it was found that relative risk from these compounds were lower than that from Cu. Comparing the relative risks from different treated wood products, As from CCA was the most limiting in terms of risk analysis.

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56 Table 3-1 Physical and chemical properties of soil horizons used in the study Parameter Organic Horizon Sandy Horizon Clay Horizon pH 6.66 5.81 6.09 Moisture content (%) 1.8 2.3 5.5 Bulk density (gm/cm 3 ) 1.27 1.43 1.35 % OM 1.80 0.40 0.53 Particle size distribution % sand 92.9 93.8 73.3 % silt 4.9 2.9 4.6 % clay 2.2 3.3 22.1 Classification as per USDA Texture Diagram Sand Sand Sandy Clay Loam CEC e (cmol c /kg) 21.2 19.1 61.2 Amorphous Fe (mg/kg-dry soil) Al (mg/kg-dry soil) 132 310 54.0 675 3,150 1,195 Totals (mg/kg-dry soil) As Cr Cu B 2.8 0.4 a 5.6 0.7 2.1 0.4 6.4 1.2 3.4 0.8 7.6 1.2 4.5 0.5 5.8 0.8 6.2 0.8 11.4 1.3 5.8 0.9 4.8 0.7 a Arithmetic mean standard deviation of three replicates. Table 3-2 Percentage mobility of preservative components calculated at the end of the experiment Preservative Component Sandy Horizon Organic Horizon Clay Horizon CCA-Cu 7.6 6.6 5.7 ACQ-Cu 7.1 5.9 5.2 CBA-Cu 7.3 6.9 4.9 ACQ-B 6.2 5.6 3.0 CBA-B 4.0 3.9 2.2 DOT-B 11.6 6.1 4.1 CCA-As 5.3 4.4 3.1 CCA-Cr 19 16 15

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57 Table 3-3 Preservative components concentrations (mg/kg) in soil surface layer Preservative Components Sandy Horizon Organic Horizon Clay Horizon CCA-Cu 11.0 1.3 a 6.47 1.4 17.3 2.4 ACQ-Cu 61.5 5.7 42.3 3.6 107 13.4 CBA-Cu 58.7 3.4 44.7 2.6 97.6 8.3 ACQ-B 22.6 2.6 15.3 1.3 34.7 4.3 CBA-B 29.4 5.4 22.3 3.1 51.2 5.4 DOT-B 142.4 10.3 96.5 7.8 224 21.4 CCA-As 10.8 1.4 7.14 0.8 24.4 2.1 CCA-Cr 10.1 0.4 8.31 0.7 16.3 0.6 ACQ-DDAC b 2.58 2.90 2.74 CBA-Tebuconazole b 2.56 2.87 2.71 a arithmetic mean standard deviation of three replicates taken from top 5 cm soil layer, b Calculated based on amount added to the column, assuming 100% retention in top 5cm of the column. Table 3-4 Risk factor calculated for preservative components based on surface layer concentration and florida soil clean up target levels (SCTLs a ) Sandy Horizon Organic Horizon Clay Horizon Preservative Components Residential Industrial Residential Industrial Residential Industrial CCA-Cu 0.073 0.00007 0.043 0.00005 0.12 0.00013 ACQ-Cu 0.41 0.00069 0.282 0.0005 0.71 0.0012 CBA-Cu 0.39 0.00066 0.29 0.0005 0.65 0.0011 ACQ-B 0.0013 0.00005 0.0009 0.00004 0.002 0.00008 CBA-B 0.0017 0.00007 0.0013 0.00005 0.003 0.0001 DOT-B 0.0084 0.0003 0.0057 0.00022 0.013 0.0005 CCA-As 5.1 0.9 3.4 0.6 11.6 2.03 CCA-Cr 0.048 0.021 0.04 0.018 0.078 0.035 a SCTL values are included in Appendix B Table B-1.

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58 Organic HorizonSandy HorizonClay Horizon Organic HorizonSandy HorizonClay Horizon Organic HorizonSandy HorizonClay Horizon Figure 3-1 Soil sample collected from a soil pit at an ifas research station 7.5 cm Pea gravel 7.5 cm Pea gravel layerlayer15 cm Pea gravel layer15 cm Pea gravel layer GeoGeo--textiletextile 45 cm soil layer45 cm soil layerStainless Stainless steel screensteel screenStainless Stainless steel screensteel screen Influent (deck runoff)Influent (deck runoff) EffluentEffluent7.5 cm Pea gravel 7.5 cm Pea gravel layerlayer15 cm Pea gravel layer15 cm Pea gravel layer GeoGeo--textiletextile 45 cm soil layer45 cm soil layerStainless Stainless steel screensteel screenStainless Stainless steel screensteel screen Influent (deck runoff)Influent (deck runoff) EffluentEffluent Figure 3-2 Soil column setup in laboratory for three soil horizons

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59 Cumulative Deck Runoff (Litres) 050100150200250 Cu (mg/L) 0246810 CCA-Cu ACQ-Cu CBA-Cu Figure 3-3 Copper concentration in deck runoff samples Cumulative Deck Runoff (Litres) 050100150200250 B (mg/L) 05101520253035 ACQ-B CBA-B DOT-B Figure 3-4 Boron concentration in deck runoff samples

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60 Cumulative Deck Runoff (Litres) 050100150200250 Concentration (mg/L) 0.050.100.150.200.250.300.35 DDAC Tebuconazole Detection LimitBelow detection limit during this part of the experiment Figure 3-5 DDAC and tebuconazole concentration in deck runoff samples Cumulative Deck Runoff (litres) 050100150200250 Concentration (mg/L) 0.00.51.01.52.02.5 CCA-As CCA-Cr Figure 3-6 Arsenic and chromium concentration in deck runoff samples

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61 Eluent Volume (mL) 0100020003000400050006000 Cu (mg/L) 0.00.10.20.30.4 CCA-Cu ACQ-Cu CBA-Cu Sandy Horizon Eluent Volume (mL) 0100020003000400050006000 Cu (mg/L) 0.000.050.100.150.200.250.300.35 CCA-Cu ACQ-Cu CBA-Cu Organic Horizon Clay HorizonEluent Volume (mL) 0100020003000400050006000 Cu (mg/L) 0.000.020.040.060.080.100.120.140.160.180.20 CCA-Cu ACQ-Cu CBA-Cu Figure 3-7 Copper concentrations in soil column eluents

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62 Sandy HorizonEluent Volume (mL) 0100020003000400050006000 Boron (mg/L) 0.00.20.40.60.81.01.2 ACQ-B CBA-B DOT-B Organic HorizonEluent Volume (mL) 0100020003000400050006000 Boron (mg/L) 0.00.10.20.30.40.50.6 ACQB CBA-B DOT-B Clay HorizonEluent Volume (mL) 0100020003000400050006000 Boron (mg/L) 0.000.050.100.150.200.25 ACQ-B CBA-B DOT-B Figure 3-8 Cumulative copper concentrations in soil column eluents

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63 Eluent Volume (mL) 0100020003000400050006000 As and Cr (mg/L) 0.000.020.040.060.08 As-Sandy Cr-Sandy As-Org Cr-Org As-Clay Cr-Clay Figure 3-9 Arsenic and chromium concentrations in soil column eluents

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64 Sandy horizon CCA-AsACQ-CuCBA-CuDOT-BDDACTebuconazole Risk factor 0123456 Figure 3-10 Relative risk factors on sandy soil when surface soil concentration was compared to SCTL

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65 Sandy horizon CCA-AsACQ-CuCBA-CuDOT-B Risk factor 0.00.51.01.52.02.53.0 Figure 3-11 Relative risk factors for potential groundwater contamination using data from sandy soil horizon column eluent concentrations CCA-AsACQ-CuCBA-CuDOT-BDDACTebuconazole Risk factor 0102030405060 Figure 3-12 Relative risk factors for potential groundwater contamination using data from deck runoff concentrations

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CHAPTER 4 COMPARISON OF METAL LEACHING FROM TREATED WOOD WHEN LEACHED WITH MUNICIPAL SOLID WASTE LANDFILL LEACHATE 4.1 Introduction The majority of waterborne wood preservatives used in recent years contain one or more heavy metals. Aqueous wood preservative solutions are infused into wood products under pressure to create a product that will resist biological decay in the harsh environment. The most prevalent wood preservative in recent years, chromated copper arsenate (CCA), contains chromium (Cr), copper (Cu) and arsenic (As). Concerns over human-health and environmental impact of As and Cr from CCA-treated wood (Cooper, 1991; Breslin and Adler-Ivanbrook, 1996; Stilwell and Gorny, 1997; Lebow et al., 1999; Solo-Gabriele et al., 2002; Lebow et al., 2003; Townsend et al., 2003a, Khan et al., 2004) prompted the wood preservation industry to develop alternative Asand Cr-free waterborne wood preservatives. Cu is the main component in many of these alternative preservatives; some preservatives also use boron (B). The alternative wood preservatives commercially available include alkaline copper quaternary (ACQ), copper boron azole (CBA), and disodium octaborate tetrahydrate (DOT). Previous research has shown that metals leach from pressure-treated wood products to some extent when exposed to water (Cooper, 1991; Cooper, 1994; Hingston et al., 2001; Lebow et al., 2003). One of the several scenarios where leaching of metals from pressure-treated wood poses a concern is final disposal (Jambeck 2004, Townsend et al., 2004a; Townsend et al., 2005). The large demand for pressure-treated wood products in 66

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67 the past few decades results in the disposal of significant amounts of these materials at the end of their service life (McQueen and Stevens, 1998; Solo-Gabriele and Townsend, 1999). Landfills represent one of the primary disposal methods for discarded pressure-treated wood products. Since treated wood does leach metals in aqueous environments, a potential concern for a landfill operator accepting this material is the fate of elevated metal concentrations. Groundwater contamination is a concern at unlined landfills. The concern at lined landfills is elevation of preservative chemical concentrations in the collected leachate. Most lined MSW landfills send their leachate for treatment to an offsite wastewater treatment plant (WWTP), and because these facilities often impose pretreatment standards, elevated metal concentrations in leachate can result in extra fees to the landfill (LF) operator or possibly the denial of service. An additional concern with respect to elevated metal leachate concentrations is the ultimate fate of these metals. In a WWTP, the metals in the leachate accumulate for the most part in the biosolids. Since biosolids are often land applied, this could result in a return of metals back to the non-landfill environment. Laboratory leaching tests are widely used to assess the likely leaching potential of wastes being landfilled. Several leaching tests have been developed and used by regulatory agencies for this purpose in the past. The toxicity characteristic leaching procedure (TCLP) was designed to simulate the leaching conditions that occur when a potentially hazardous waste is disposed in a municipal solid waste (MSW) landfill (Francis et al., 1984; Francis and Maskarinec, 1986). The toxicity characteristic (TC) limit for As and Cr are each 5 mg/L. CCA-treated wood was found to leach As using TCLP at concentrations greater than the TC limit (Townsend et al., 2004a; Stook et al.,

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68 2005; Townsend et al., 2005). While the Cu-based preserved wood products do not leach As or Cr, they do leach several times more Cu than CCA-treated wood, especially under TCLP (Stook et al., 2005). Although the TCLP has been used to assess the leaching of metals from waste disposed in MSW landfills, this procedure has potential limitations in simulating the leaching conditions that truly occur in a MSW landfill (Cernuschi et al., 1990; Poon and Lio, 1997; Hooper et al., 1998; Dubey et al., 2004). An alternative approach for assessing the ability of a pollutant to leach from waste co-disposed in a MSW landfill is to perform a batch leaching test similar to TCLP, but using actual landfill leachate as the leaching solution (Hooper et al., 1998; Jang and Townsend, 2003a; Dubey et al., 2004; Halim et al., 2004). The objective of the research presented in this chapter was to assess the potential impact on leachate quality on disposal of discarded treated wood products in MSW landfills. The leaching of As, Cr, Cu and B from several types of pressure treated wood (CCA, ACQ, CBA, and DOT) using leachate collected from twenty-six MSW landfills in Florida was examined. The TCLP, the synthetic precipitation leaching procedure (SPLP) and California’s waste extraction test (WET) were also performed on these samples to compare the results in different leaching environments. The goal of this research was to provide data that would help assess the true impact of pressure treated wood disposed of in sanitary landfills. The results are useful to those evaluating disposal options for 1) CCA-treated wood currently present in the wood waste stream, and 2) the copperand boron-based treated wood products that have started entering the wood waste stream.

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69 4.2 Materials and Methods 4.2.1 Sample Collection and Preparation Pieces of dimensional CCA-, ACQ-, CBAand DOT-treated lumber were purchased from different home improvement stores in Florida. The sawdust generated on cutting the dimensional lumber into small blocks using a power saw was collected and used as samples in this study. Separate blades were used for each wood type to avoid cross contamination and the power saw was vacuum cleaned prior to sample preparation for each wood type. 4.2.2 Determination of Total Extractable Metal Concentrations Total extractable arsenic, copper, chromium and boron concentrations in the treated wood sawdust samples were obtained through a hot acid digestion (Method 3050B, US EPA, 2003) and analyzing the digestates using inductively coupled plasma atomic emission spectroscopy (ICP-AES, Thermo Electron Corporation, Trace Analyzer) as per Method 6010B (US EPA, 2003). 4.2.3 Landfill Leachate Collection Leachate samples were collected from twenty-six MSW landfill sites in Florida. Eleven (sites 2,5,7,9,10,14,16,20,24-26) of the twenty six landfill sites were active landfills, which means they were accepting waste when samples were collected from the leachate collection system. The waste accepted per day at these active sites ranged from 370 to 1200 metric tons per day. The remaining fifteen sites were closed at the time of sample collection. The lined cell areas from which leachates were collected for these twenty six landfill sites ranged from 4.85 to 50.6 hectares. The variety of sites provided the opportunity to collect wide varieties of leachate having leachate parameters over broader ranges. Leachate samples were collected either from the sump of the leachate

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70 collection system (LCS) or from the leachate collection pipe outlet into a manhole of the LCS. The leachate samples were collected in 5-gallon HDPE containers while maintaining minimum headspace. Leachate samples were bailed using a Teflon bailer at majority of landfill sites. At a few sites, the leachate sample was collected using the landfill’s existing pumping system. The leachate parameters measured in the field immediately after collection included pH and specific conductance. The leachate samples were transported to the laboratory and stored at 4 o C until the leaching test was performed using these leachates as a leaching fluid. Separate aliquots of each leachate sample were collected as per sampling procedures of different leachate parameter analyses. 4.2.4 Laboratory Leaching Procedures Wood samples were subjected to 29 different extraction solutions, 26 of these were the landfill leachates and 3 were those prescribed by the following regulatory leaching procedures: TCLP, SPLP (US EPA, 2003) and WET (CCR, 1998). The pH of the landfill leachates ranged from 5.75 to 8.10. This pH range is typical of modern MSW landfills (Reinhart and Grosh, 1998; Kjeldsen et al., 2002). The TCLP solution was prepared by mixing 0.1 M acetic acid and 1 N sodium hydroxide in a ratio of 1:11 with DI to achieve the pH of the solution as 4.930.05. The SPLP solution was prepared by mixing sulfuric acid and nitric acid in a ratio of 3:2. The pH of the solution used was 4.200.05. The WET, a supplementary test in the state of California along with TCLP for hazardous waste determination, utilizes a buffered citric acid solution as the leaching fluid. The WET extraction solution was prepared by titrating a 0.2 M citric acid solution with 4.0 N sodium hydroxide to a pH of 5.0 0.05.

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71 In order to compare the leaching results from the twenty nine leaching fluids, the extraction procedure for each of the fluids was kept similar as presented in Table 4-1. For the WET test, nitrogen purging of the leaching fluid was conducted immediately prior to extraction. After extraction in a rotary extractor, samples were filtered using a pressurized filtration apparatus with a 0.7-m borosilicate glass fiber filter (Environmental Express TCLP filter). The filtrate was preserved with a few drops of concentrated nitric acid (to reduce pH <2.0). The extraction for each sample type was performed in triplicate for each of the twenty nine extraction fluids. The arithmetic mean of the concentrations from these three replicates and the corresponding standard deviation are presented in this paper. Laboratory blanks, matrix spikes, and calibration checks were performed when appropriate for analysis as a form of quality assurance/quality control (QA/QC) practices. Analysis of blank samples were consistently below detection limits, matrix spike samples and calibration check samples showed recoveries between 87 and 110%. 4.2.5 Impact of Solution pH on Leaching ACQ and CBA sawdust samples were leached with modified TCLP solutions at pH of 5.97 and 7.65 adjusted with addition of 1 N NaOH to study the impact of pH change of TCLP solution on Cu leaching from these treated wood products. Two pH values from typical MSW landfill leachate pH range were chosen for the extraction. Additionally, a pH impact experiment was also performed by adjusting pH of DI water with 1N HNO 3 and 1N NaOH as needed in the pH range of 4.3 to 8.4. The pH was monitored and adjusted throughout the leaching duration of 18hours. Other procedures for these leaching tests were similar to those for TCLP. Detailed procedure and results of pH impact study are presented in Appendix A.

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72 4.2.6 Leachate Analysis Leachate collected from the landfills was characterized for typical leachate quality parameters, including metals, sulfides, alkalinity, total dissolved solids (TDS), biochemical oxygen demand (BOD 5 ), chemical oxygen demand (COD), total organic carbon (TOC) and ammonia. US EPA methods (US EPA, 2003) and other standard methods (APHA, 1995) were employed when applicable. The detection limit for As, Cu, Cr and B were 12g/L, 4g/L, 4g/L and 6g/L, respectively. Volatile fatty acids were measured by gas chromatography. The equipment used was a Shimadzu gas chromatograph (Shimadzu GC 9-AM) with a flame ionization detector (FID). Samples were centrifuged at 10,000 rpm for 10 minutes and the resultant supernatant was acidified with 1:9 v/v parts sample to 20% H 3 PO 4 containing 1000 mg/L of isobutryate. Two micro-liters of sample were injected onto a 2-m long, 3.2 mm wide internal diameter glass column packed with 10% SP1000 and 1% H 3 PO 4 in Chromosorb WAW 100/120. 4.3 Results and Discussion 4.3.1 Total Metal Content in the Sawdust Samples The CCA sawdust samples contained 2350 50 mg-As/kg (arithmetic mean of three replicate corresponding standard deviation), 2890 56 mg-Cr/kg and 1330 10 mg-Cu/kg, which is equivalent to CCA Type-C treated wood with 5.4 kg/m 3 retention. The rated retention for CCA-treated wood as indicated by the manufacturer was 6.4 kg/m 3 . It should be noted here that the rated retention values reported by the manufacturer is based on the outer 1.5 cm (0.6 in.) of the wood. The total metal analysis results presented here was conducted on the sawdust collected through the entire cross section of the wood. Copper and B concentrations in the ACQ and CBA sawdust samples were 2860 40 mg-Cu/kg, 360 20 mg-B/kg and 5420 120 mg-Cu/kg, 810

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73 20 mg-B/kg respectively. Calculated retention values based on Cu concentration for ACQ and CBA treated wood were 1.9kg/m 3 as CuO and 3.6kg/m 3 as CuO, respectively. Rated retention of ACQand CBA-treated wood was 4.0kg/m 3 and 6.4kg/m 3 respectively. The borate treated wood contained 0.15% of B (1690 15 mg-B/kg) by weight (retention value of 5.07kg/m 3 as B 2 O 3 ). 4.3.2 Landfill Leachate Characterization Table 4-2 summarizes the chemical characteristics of the leachates collected from the twenty-six landfill sites. Conductivity readings correlated with the TDS value as expected. A number of landfill investigation studies (Pohland and Englebrech 1976) have suggested that the stabilization of waste proceeds in sequential and distinct phases. In general any landfill site can be broadly classified as either being in an acidogenic phase or in a methanogenic phase based on the prevalent stage of waste decomposition at that particular site. Leachate pH is considered as an indicator of these phases. Although the transition from the acidogenic phase to the methanogenic phase is not distinct, landfill leachate with pH < 7.0 is generally considered to be in acidogenic phase. The twenty five landfill sites out of total twenty six from where the leachates were collected have been classified into the two categories. The site 18, consisting of a vertical well at a bioreactor landfill was not included in this classification as the leachate from this well was very different in terms of leachate parameters that were measured. Out of a total of twenty five landfill sites, fourteen were found to be in acidogenic phase and remaining eleven in methanogenic phase based on the pH of the leachate samples from these sites. Another parameter which may indicate the phase of waste degradation in a MSW landfill is the volatile fatty acid (VFA) concentration in the leachate. Among the landfill sites identified as to be in acidogenic phase the average VFA concentration was 498.2mg/L

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74 with a range from <1.0mg/L to 3420mg/L. For the leachates identified as methanogenic leachate, only four out of twelve leachates had VFA concentration above detection limit with average and range of concentrations as 7.6mg/L and (<1.0mg/L to 53 mg/L) respectively. The averages pH for the acidogenic and methanogenic leachate was 6.60 and 7.30 respectively. Concentrations of other leachate parameters evaluated were in same order of magnitude for both categories of leachate. 4.3.3 Average Preservative Leaching From Pressure-Treated Wood under Different Leaching Environments The results of the average inorganic preservative components leaching from the different pressure treated wood samples evaluated in this study are presented in Figure 4-1. The average concentration axis for CCA, ACQ and CBA graphs are in logarithmic scale to present the data from different leaching tests together. MSW concentrations in the figure represent the average of various element concentrations obtained on leaching with 26 landfill leachates as extraction fluid. 4.3.3.1 Chromated copper arsenate treated wood The average As, Cr and Cu concentrations from CCA-treated wood is presented (Figure 4-1 (A)). The amount of As and Cr leached from CCA-treated wood in TCLP, SPLP, WET and MSW leaching followed the same trend as observed previously in Townsend et al., (2004). The highest As leaching was observed with WET (56 mg-As/L) followed by TCLP (11.3 mg-As/L), SPLP (7.7 mg-As/L) and MSW (4.4 mg-As/L) respectively. The average final pH values for WET, TCLP SPLP and MSW leachates were 4.88, 4.84, 4.74 and 6.95 respectively (with initial pH as 5.00, 4.93, 4.20 and 6.97 respectively). The pH dropped for all the extractions except for SPLP where the final pH was higher than the initial pH. SPLP solution does not have any buffering capacity and

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75 with typical CCA treated wood pH around 4.90-5.00, the final pH of the SPLP extract went up with wood pH controlling the pH change. The average Cr concentration followed the same pattern as As with higher levels observed with the WET extraction (41mg-Cr/L) followed by TCLP (3.7 mg-Cr/L), SPLP (1.95 mg-Cr/L) and average MSW concentrations (1.2 mg-Cr/L). TCLP As concentration exceeded the TC limit of 5 mg-As/L. As (56 mg/L) and Cr (41 mg/L) concentration under WET leaching test also exceeded the corresponding soluble threshold limit concentration (STLC) of 5mg/L for both the elements. Copper leached the most under WET (73 mg/L) followed by TCLP (11 mg/L), MSW (4.5 mg/L) and SPLP (2.2 mg/L). Similar observations were made by Townsend et al., (2004) except for the fact that more Cu leached with MSW leachate compare to TCLP. As can be observed from the pH values mentioned above, pH of the SPLP, WET and TCLP leachate were statistically similar (4.74 4.88) with average pH of MSW (6.95) greater than 2 units higher than the other three. Although pH was higher for MSW leachate compared to SPLP, higher Cu leaching was observed with MSW leachate. This could be due to the presence of organic acids which tend to complex with Cu producing soluble complexes. The average concentration of VFA in the leachate was 215mg/L. Along similar lines, citrate in WET extraction fluid extracted more Cu compare to acetate in TCLP fluid because citrate makes more stable complexes than acetate due to its multi-dentate character (Stumm and Morgan, 1996). In previous studies as well, more Cu leaching has been observed in TCLP compare to SPLP (Townsend et al., 2004). One more point that needs to be noted here is, in the WET test twice the amount of sample is leached compared to other leaching tests reported here. WET uses a liquid-to-solid ratio

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76 of 10:1 where as other leaching tests use a liquid-to-solid ratio of 20:1. A previous study (Townsend et al., 2006) has shown that for most elements including As, Cr and Cu, the element concentrations in the leachate decrease as the liquid-to-solid ratio is increased. As stated earlier, Cu is not a TC element, but it is regulated in the state of California. A Cu concentration of 73mg/L in the WET leachate exceeded the STLC limit for Cu of 25mg/L. Hence, the CCA-treated wood sample used in this study fails TCLP for As and fails WET for all three elements (As, Cr and Cu). The variation of Cr, Cu and As leaching with different landfill leachate fluid has been discussed in more detail in subsequent sections of this chapter. 4.3.3.2 Alkaline copper quaternary treated wood Average inorganic preservative components leaching from ACQ-treated wood under WET, SPLP, and TCLP and leaching with MSW landfill leachate have been presented (Figure 4-1 (B)). The average final pH of the extracts under different leaching tests was 4.89 for WET, 5.70 for SPLP, 4.86 for TCLP and 7.03 for MSW leachates. Comparing to the initial pH as presented in Table 4-1, it was found that there was not a significant change in pH of TCLP, WET and landfill leachate, but the final pH of the SPLP extract went up by 1.5 points. Cu leaching for ACQ followed the same trend as for the CCA sample presented in the previous section. Higher Cu leaching was observed under WET (200 mg/L) followed by TCLP (47 mg/L), MSW (24 mg/L) and SPLP (20mg/L). A similar trend was observed for SPLP and TCLP Cu leaching for ACQ treated wood by Stook et al. (2005). A comparatively lower pH of TCLP and WET along with presence of citrate in WET and acetate in TCLP resulted in more Cu leaching out in these extractions. The average Cu concentrations for SPLP and MSW leaching were similar although pH was higher for MSW, this again could be due to organic acids in

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77 MSW leachates (Stumm and Morgan, 1996). Cu concentrations for ACQ samples also exceeded the STLC limit (for WET) of 25mg/L for Cu. Therefore, the ACQ-treated wood sample used in the present study would qualify as a hazardous waste in the state of California. B leaching from ACQ sawdust was highest for WET leachate (31mg/L) followed by the concentrations in MSW (17.2 mg/L), TCLP (9.1 mg/L) and SPLP (8.4 mg/L). 4.3.3.3 Copper boron azole treated wood The average Cu and B leaching from CBA-treated wood sample have been presented (Figure 4-1(C)). Copper leaching was highest from CBA-treated wood under WET (average final pH= 4.90) followed by TCLP (average final pH = 5.05), MSW (average final pH = 6.83), and SPLP (average final pH = 5.54). The change in pH followed a similar trend as ACQ, but the final pH was closer to the pH of CBA treated wood samples (pH of 5.80). Formation of soluble Cu complexes with organic acids (average VFA concentration in leachates used as leaching solutions was 214mg/L) could be one of the factors leading to the observed trend of Cu concentrations in different leachates. Average Cu concentrations in the leachates samples were 327 mg/L for WET, 104 mg/L for the TCLP, 53.7 mg/L for the MSW leachates, and 31.0 mg/L for SPLP. Stook et al. (2005) also observed more Cu leaching from CBAtreated wood under TCLP compared to SPLP. When CBA sawdust samples were leached with modified TCLP solutions at pH of 5.97 and 7.65, similar concentrations of Cu leached in these two extractions compare to regular TCLP. On performing a pH impact experiment by adjusting pH of DI water with 1N HNO 3 and 1N NaOH as needed, it was found that for the pH range of 4.3 to 8.4, Cu concentrations were reduced marginally as the pH of the extraction solution was

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78 increased (results are presented in detail in Appendix C). These two observations indicated that pH was not a major factor influencing the Cu leaching from CBA-treated wood in the pH range encountered in this experiment. Presence of multiple inorganic (Cl , SO 4 2, CO 3 2etc.) and organic ligands (i.e. CH 3 COO ) in a MSW leachate would lead to the formation of soluble Cu complexes resulting in the higher Cu concentration in the resulting leachate when the treated wood is leached with landfill leachate as the leaching solution. Boron leaching of CBA samples followed the same trend as for the ACQ samples with highest leaching reported for WET leachate (65mg/L) followed by MSW (33mg/L), TCLP (32mg/L) and SPLP (17mg/L). 4.3.3.4 Borate treated wood Average final pH of the extracts were 4.95 (WET), 4.86 (TCLP), 6.85 (SPLP) and 7.10 (average for leaching with MSW leachates). There was a substantial increase of pH in SPLP extraction (from 4.20 to 6.85). Highest B leaching was observed under WET extraction (134mg/L). TCLP, SPLP and MSW leachates (average of 26 extractions in triplicates) concentrations were in statistically similar range of 65 mg/L, 72mg/L and 62 mg/L respectively. Higher concentrations were observed with lower final pH of the extraction fluid. 4.3.4 Variation of Preservative Leaching with Different Landfill Sites 4.3.4.1 Arsenic and Cr leaching as a function of landfill leachate source Arsenic leaching from CCA-treated wood samples leached with various landfill leachates as the leaching fluid has been presented in Figure 4-2 (A), to compare the variation in leaching with different leachates. Arsenic concentration in the leachate from site -18 was the highest among the leachates produced with MSW leachates. This concentration was higher than the corresponding SPLP concentration but lower than

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79 TCLP concentration. On comparing the As concentrations in the CCA-leachate on leaching with various MSW leachates with As TC limit of 5 mg/L, it was found that As concentration in six out twenty six CCA-leachate samples exceeded the TC limit for As. For the remaining 20 CCA-leachates As concentration varied between 0.74 mg/L to 4.80 mg/L. No specific trend with leachate pH was observed for As leaching. The pH of the leachate samples (used for extraction) varied from 5.80 to 8.10. In a previous study investigating the pH impact on preservative leaching from CCA-treated wood, As concentration was found to be similar in the samples in this pH range (Townsend et al., 2004). The average TCLP concentration was greater than that measured using actual landfill leachates. Thus, while some recent studies suggest that As may leach more in actual landfill leachate compared to TCLP (Hopper et al., 1998; Halim et al., 2004); the same trend was not observed for CCA treated wood samples evaluated in this study. It has also been found in a previous study (Dubey et al., 2004) that As leaching from TCLP and MSW leachates vary with the pH of the waste material being evaluated. For the waste materials evaluated in that study, it was found that waste with pH greater than pH=7 leached more arsenic with landfill leachates compare to TCLP while the waste with pH= 2.9 thru 6.3 leached more arsenic with TCLP compared with nine landfill leachates used in the study. The pH of the CCA sawdust used in the present study was 4.83 (similar to the second category of the waste evaluated in study by Dubey et al., (2004)). On comparing the As leaching from different landfill leachates with leachate parameters it was observed that there was a general trend of higher As concentration in the extract produced from the landfill leachates that has a higher alkalinity concentration (R 2 =0.38).

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80 Chromium leaching from CCA-treated wood samples leached with various landfill leachates as the leaching fluid is presented in Figure 4-2(B). The Cr concentration (5.1mg/L) in the CCA leachate produced from MSW landfill leachate from site-18 exceeded the TC-limit for Cr (5mg/L). The TCLP concentration of 3.74 mg-Cr/L was greater than that measured using most of the actual landfill leachates. Here again, although, some recent studies suggest that chromium may leach more in actual landfill leachate compare to TCLP (Hopper et al., 1998; Halim et al., 2004); the same was not observed for Cr waste evaluated in this study. This again could be the result of the pH of the CCA sawdust as explained for As in the previous paragraph. Four out of 26 CCA leachate samples with MSW leachates exceeded the corresponding SPLP concentrations. For the remaining 22 CCA-leachates Cr concentration varied between 0.46 mg/L to 1.99 mg/L. When comparing the Cr leaching from different landfill leachates with leachate parameters, no trend with leachate pH was observed but there was a general trend of higher Cr concentration in the extract produced from the landfill leachates that has a higher alkalinity concentration (R 2 = 0.55). 4.3.4.2 Boron leaching as a function of landfill leachate source Boron leaching from pressure treated wood samples leached with several landfill leachates as the leaching fluid has been presented in Figure 4-3. For the DOT sawdust sample, the B concentration varied from 61mg-B/L to 76 mg-B/L. If 100% B leach out from DOT treated wood the leachate concentration would be 84.5mg/L. Out of 26 landfill sites three samples had concentrations higher than the corresponding SPLP concentration. Ten of the DOT leachates were characterized by concentrations between TCLP and SPLP concentrations. The remaining samples had concentrations below the TCLP concentration. In general, B leached at higher concentrations from DOT treated

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81 wood for all of the leaching fluids relative to that for ACQand CBA-treated wood; this is likely due to the presence of higher boron concentrations in DOT treated wood. For the ACQ and CBA treated wood, in general TCLP and SPLP, B concentrations were lower than B concentrations in the leachate produced on leaching with landfill leachates. Variation of the B concentrations with various landfill sites followed similar patterns for both ACQ and CBA samples with relatively higher concentrations recorded for the CBA samples. 4.3.4.1 Copper leaching as a function of landfill leachate source Copper leaching from pressure treated wood samples leached with several landfill leachates as the leaching fluid has been presented (Figure 4-4). For the CCA sample, Cu concentration varied from 0.8mg-Cu/L to 23 mg-Cu/L. Out of 26 landfill leachates, two samples had concentrations higher than the corresponding TCLP concentration as shown in Figure 4-4(A). Both of these had highest concentrations of ammonia (1620 mg/L and 625 mg/L) in the leaching fluid. Copper concentration was found to be higher in thirteen samples compared to the SPLP concentration. For the ACQ treated wood, in general the TCLP Cu concentration was higher than Cu concentrations in the leachate produced on leaching of ACQ sawdust samples with landfill leachate with the exception of site-13 (47.8 mg/L). In fifteen out of twenty six landfill leachate extractions, Cu concentrations in the resulting leachates were higher than the corresponding concentrations in the SPLP extracts (Figure 4-4(B)). The final pH of ACQ landfill leachate extracts varied from 5.91 to 7.47. In the pH impact experiment on this pH range for ACQ treated wood sample, Cu concentration reduced to 27mg/L at pH = 8 compare to 41mg/L at pH=4.8 (see Appendix A for details). Lower pH in TCLP extract compare to MSW leachate extracts could have impacted Cu leaching.

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82 For the CBA samples the average Cu concentrations in the leachate produced from MSW leachates was lower than the TCLP Cu concentration. Comparing to impact of pH on Cu leaching from CBA (as described in section 4.3.3.3, see also Appendix A for further detail), it was found that reduction of Cu leaching in CBA treated wood with an increase in pH was not that pronounced as for ACQ samples. The total Cu concentration in the CBA sawdust samples used in the leaching tests was 5420 mg/kg, which is nearly four times the Cu concentration in CCA (1330 mg/kg) and nearly two times the total Cu concentration in ACQ (2860 mg/kg). In the Cu-rich CBA system, the hydrated Cu-ion makes a temporary complex with amine (or ammonia) solution which helps to minimize metal corrosion in the treatment plant and improve Cu penetration and distribution in the treated lumber (Freeman et al., 2004). The high amine and Cu concentration in CBA-treated wood compare to CCA and ACQ treated wood may have resulted in higher Cu leaching as Cu has been shown to make stable soluble complexes with ammonia in the pH range observed in the experiment (details on next paragraph). The overall trend of Cu concentrations on leaching with different leachates follows similar pattern for all the three wood types. At a closer look on the graphs for copper concentration vs. sites the three plots with CCA, ACQ and CBA show nearly identical patterns. Efforts were made to identify what factor in a leachate influenced Cu leaching. Variation of amount of Cu leached with ammonia concentration in the leachate has been presented (Figure 4-5). As observed in the figure there is a relationship between ammonia concentration in the landfill leachate and Cu concentration in the leachates produced on leaching with MSW leachates (R 2 = 0.83 for CCA, 0.43 for ACQ and 0.64 for CBA) leaching. Addition of ligands like NH 3 to Cu(II) in aqueous solution leads to

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83 stepwise formation of soluble stable Cu complexes in pH range of 6 thru 9 (Nriagu, 1979). Humar et al., (2004) has also observed that higher amounts of Cu leached out from chromated copper borate (CCB) treated wood when mixture of ammonia and oxalic acid was used as an extraction solution compared to when only oxalic acid was used as the leaching solution. More and more landfill sites are adopting bioreactor technology for faster stabilization and other benefits associated with this. A higher ammonia concentration has been observed compared to traditional landfills as in bioreactor landfills the rate of ammonification increases with moisture addition and/or recirculating leachate (Onay and Pohland, 1998; Barlaz et al., 2002). Higher ammonia in the bioreactor landfill leachate may be the concern for leading to elevated Cu concentration in the leachate on disposal of Cu-rich waste such as ACQ, CBA and even CCA-treated wood. As mentioned in the previous section, the leachate quality of the site 18 leachate was much different compared to other leachates. The pH of the leachate was 8.10. BOD 5 , COD and Ammonia concentrations were 2,400mg/L, 10,900mg/L and 1620mg/L respectively. The Cu leaching was highest in the leachate produced on leaching with this leachate and statistically different compared to leaching with other leachates for CCA and CBA samples. For ACQ sample, Cu leaching with leachate from this site was the second highest among the Cu concentrations on leaching with landfill leachates. 4.3.5 Comparison of Leaching by Acidogenic and Methanogenic Leachates The Cu, Cr, B and As concentrations in the leachates produced by leaching with treated wood with leachates have been grouped separately for acidogenic leachates and methanogenic leachates (site 18 was not included in this classification as mentioned previously). The average concentrations and corresponding standard deviations for

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84 different elements is presented in Table 4-3. Statistical ‘t-test’ was performed on the concentrations from the two leachate types and the P-value corresponding to the ‘t-test’ is also presented in Table 4-3. Comparing different elements in Table 4-3, the average preservative concentrations following leaching with these two groups of leachates were significantly different except for boron concentration from CBA samples. 4.4 Regulatory and Disposal Implications The CCA-treated wood has been reported to exceed TC-limit for As in many instances (Townsend et al., 2005. 2004). A similar observation was made in the present study. Limitations to TCLP have been identified and many recent studies have suggested that TCLP does not always predict the leaching concentration in a MSW landfill (Hooper et al., 1998; Jang and Townsend, 2003; Halim et al., 2004; Dubey et al., 2004). In some of these studies, TCLP was found to over-predict the MSW leaching concentrations and in some of the other cases reverse trend was observed. For example, Jang and Townsend (2003), found lead from electronic devices to leach more with the TCLP compared to MSW leachates. Both Hooper et al. (1998) and Halim et al (2003) measured arsenic leachability at greater concentrations with actual landfill leachates compared to TCLP. Hopper et al. (1998) hypothesized that negatively charged oxy-anions such as arsenic are unlikely to complex with negatively charged acetate ions in the TCLP solution, and thus other factors in the landfill leachate caused arsenic to leach more. Halim et al. (2003) postulated that high amounts of organics in the municipal landfill leachate may lead to a reducing condition resulting in the conversion of arsenic (V) to arsenic (III), which is more soluble at high pH. Additionally they suggested that under TCLP conditions the arsenate would precipitate with calcium, but under landfill leachate conditions carbonate

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85 would preferentially precipitate with calcium, thus resulting in higher arsenic concentrations. In the present study, the average As concentration produced by leaching with MSW leachate was below the TCLP concentration with all the concentrations from different leaching tests (except WET) were in similar order of magnitude. Dubey et al. (2004) has found a trend with arsenic waste sample with pH<7 leaching higher concentration in TCLP than MSW leachates and for the As-waste with pH>7 (of waste), higher concentration leached with MSW leachate compared to TCLP. The As concentrations produced by leaching with MSW leachates varied from 0.3 to 8.4 mg/L with the majority of samples having a concentration between 3 mg/L to 5 mg/L. The results from the present study shows that CCA-treated wood, if disposed in a MSW landfill, could potentially increase the As and Cr concentrations in the leachates, a concern for leachate management. Several cases are being cited in the landfill industry where leachates had to be hauled over a long distances from the local WWTP for treatment due to high concentrations of pollutants, such as As, in the leachates. As stated earlier, most of the WWTP end up sending off their end-product “biosolids” for land application. The WWTP is generally not designed to treat heavy metals and, therefore, high concentration of heavy metals in the leachate will be transferred to the biosolids, which may limit its reuse. The Cu-based alternatives studied were found to leach Cu greater (a degree of magnitude higher) than CCA-treated wood. The Cu concentrations leached using the landfill leachate samples varied somewhat among the sites. If the Cu-based alternatives are disposed in MSW landfill, the present study indicates that it may lead to elevated

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86 concentration of Cu in the MSW landfill leachate, Cu is toxic to aquatic organisms at very low concentrations (Flemming and Trevors, 1989) and has also been listed as one of the heavy metal toxicants to methanogens (Bitton, 2005). High boron leaching was also observed when MSW leachates are used as the leaching fluid. The boron concentrations for all the samples exceed the groundwater cleanup target level of 630g/L. The elevated concentrations of boron in the landfill leachate will also pose a concern for biosolid reuse as soils with boron concentration greater than 100 mg/kg are toxic to certain plants (Adriano, 2001). A variation of preservative leaching from treated wood in different extractions solutions was observed. The preservative leaching was found to vary with leachate chemistry when landfill leachate was used as an extraction fluid. Tr ends of higher element leaching with higher concentrations of certain leachate parameters has been identified and presented in the previous sections. Although using landfill leachates instead of TCLP fluid does give an advantage of having organic and inorganic constituents (the factors which influence metal leaching) similar to what will be encountered in a real landfill; it is important to note that there are many factors that can not be simulated in a laboratory leaching test that occur in a landfill (e.g., sorption, precipitation, reducing conditions). Heavy metals can be removed from solution by these mechanisms. Jambeck (2004) has simulated disposal of CCA-treated wood in a MSW landfill environment. Two percent CCA-treated wood by weight was disposed with other components of MSW. The maximum As, Cr and Cu concentration observed in the leachate was 3.8mg/L, 4.0mg/L and 0.6mg/L respectively. Extrapolating (assuming

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87 linear relationship) to a scenario of 5% treated wood disposal (TCLP assumes 5% co-disposal) in a MSW landfill, the maximum concentration would be 9.5mg/L, 10mg/L and 1.5mg/L for As, Cr and Cu respectively. In the leaching tests with CCA-treated wood in this study, As, Cr and Cu concentrations measured with TCLP were 11.3mg/L, 3.75mg/L and 10.9mg/L respectively. Comparing the two set of concentrations, it was found that TCLP concentration was similar for As in two experiments. Chromium was under predicted and Cu was over predicted with TCLP. Copper is less soluble in anaerobic conditions and has been found to precipitate out in the presence of sulfides generally present in reducing landfill conditions (Erses and Onay, 2003). Comparing the concentrations measured with landfill leachates, it was found that As and Cr concentrations measured in the leachate were lower than the predicted lysimeter concentrations. Copper concentrations in batch test with leachates were higher than the predicted lysimeter value for most of the CCA leachates. It should also be noted that although the preservative concentrations were lower in the simulated landfills compared to the concentrations observed in batch leaching tests of the present study, the concentrations in experimental lysimeter were significantly elevated for As and Cr even with 2% co-disposal of treated wood in simulated MSW landfill, a concern for leachate management and treatment. A recent review study by Solid Waste Association of North America (SWANA) applied research foundation’s disposal group concluded that “MSW landfills can provide for the safe, efficient, and long-term management of disposed products containing RCRA heavy metals without exceeding limits that have been established to protect public health and the environment” (SWANA, 2004). The study has focused on RCRA heavy metals

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88 and has collected leachate data from USEPA Leach 2000 database on these elements and compared them to the corresponding TC-limit. The RCRA heavy metal concentrations were below the TC-limit for all the leachate concentrations reported. When the leachate concentrations were compared with the four local government pretreatment standards at four counties at different parts of the country, it was found that average concentrations of As and Hg in the landfill leachate exceeded one out of four pretreatment standards. For the treated wood products As and Cr are on RCRA TC list (Cu is not included in this list). With the new As drinking water limit of 10g/L becoming effective from January 1, 2006, the pretreatment standard for As may also be subsequently lowered at many of the WWTP facilities. Therefore, even though disposal of treated wood products may not result in leachates exceeding TC limit, but it may result in increase in leachate treatment cost and management problem for a landfill operator and potentially could also limit the reuse of biosolid produced at the WWTP receiving the leachates. 4.5 Summary In this study CCA-, ACQ-, CBAand DOT-treated wood products were leached with 26 different landfill leachates and also with TCLP, SPLP and WET procedure. Leaching of preservative components was influenced by leachate chemistry. Copper leaching from CCA-, ACQand CBA-treated wood was similar in magnitude when leached with landfill leachates compared to TCLP and SPLP concentrations. Comparing with the Cu concentrations in the simulated landfill experiment (Jambeck, 2004), higher Cu concentration was observed in the batch leaching test with landfill leachate as leaching fluid. It is hypothesized that during anaerobic phase of landfill Cu is less soluble and will be precipitated out of solution. Over longer period of time, if landfills are slightly aerobic or when with operating a landfill as aerobic bioreactor the

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89 concentration of Cu in leachate may become elevated. Arsenic and Cr TCLP concentrations from CCA-treated wood were found to be in the same range as MSW leachate leaching with the majority of leachate concentrations at a level below the TCLP concentration.

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90 Table 4-1. Summary of leaching test procedures used in this study Standardized Leaching Test TCLP WET SPLP MSW leachate pH of leaching solution 4.93 0.05 (acetic acid and sodium hydroxide) 5.00 0.05 (citric acid and sodium hydroxide) 4.20 0.05 (sulfuric and nitric acids) 6.97 a Solid to liquid ratio (gram of waste to liter of solution) 100g/2L 200g/2L 100g/2L 100g/2L Extraction period 18 2 hrs 48 hrs 18 2 hrs 18 2 hrs a Average of 26 landfill leachates.

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91 Table 4-2 Composition of landfill leachate collected from twenty six landfill sites Parameter Present Study (Overall) Range Reported in Literatures a Leachates from Landfills in Acidogenic Phase Leachates from Landfills in Methanogenic Phase pH 6.97 b (5.75-8.10) c 4.5-9.0 c 6.60 (5.75-6.89) 7.30 (7.0-7.57) Conductivity (ms/cm) 7.63 (1.54-31.2) 2.5-3.5 5.6 (1.54-11.82) 8.10 (2.90-13.3) TDS (mg/L) 3,830 (880-15,300) NR d 3,160 (880-8,000) 3,630 (1,380-5,540) Alkalinity (mg/L as CaCO 3 ) 2,500 (400-10,500) NR 1,660 (400-3,750) 3,890 (1,050-4,900) TOC (mg/L) 380 (46-1,890) 30-29,000 420 (46-1,890) 280 (80-600) BOD 5 (mg/L) 430 (7.5-2,400) 20-57,000 500 (7.5-1,980) 130 (25-285) COD (mg/L) 2,020(220-10,930) 140-152,000 1,860 (220-9,660) 1,400 (330-2840) BOD 5 /COD 0.18 (0.02-0.74) 0.2 (0.02-0.74) 0.11 (0.03-0.29) Sulfides (g/L) 2,360 (10-32,000) NR 206 (10–1,450) 4,670 (10-32,000) Ammonia-N (mg/L) 325 (11.5-1620) 50-2,200 220 (11-500) 350 (90-665) Total VFA (mg/L) 215 (<1.0 – 3420) 498 (<1.0–3420) 7.7 (<1.0-53.1) As (mg/L) 0.035 (0.012-0.165) 0.01-1.0 0.021 (0.012-0.037) 0.05 (0.012-0.165) B (mg/L) 1.50 (0.02-5.50) NR 0.8 (0.010-2.0) 2.15 (0.02-5.50) Cr (mg/L) 0.043 (0.006-0.164) 0.02-1.50 0.03 (0.006-0.09) 0.05 (0.01-0.16) Cu (mg/L) 0.031 (0.011-0.10) 0.005-10 0.05 (0.006-0.101) 0.02 (0.004-0.071) Sites e 1-26 2-5, 7-10, 15-17, 19-20, 24 1, 6, 11-14, 21-23, 25, 26 a (Reinhart and Grosh, 1998; Kjeldsen et al., 2002) b Average; c Range (Min-Max); d NR=Not reported, e Site 18 was not included in acidogenic and methanogenic classification.

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92 Table 4-3 Comparison of preservative leaching using acidogenic and methanogenic leachates for leaching Preservation Type Elements Concentration in acidogenic leachate Concentration in methanogenic leachate P-value ( = 0.01) Arsenic 3.72 1.10 5.00 1.7 0.0004 Chromium 0.79 0.3 1.32 0.6 0.00001 CCA Copper 2.72 1.7 4.95 3.5 0.0015 Copper 20.6 6.1 26.6 11.7 0.011 ACQ Boron 16.0 2.5 18.4 4.0 0.005 Copper 49.5 9.2 54.3 11.3 0.06 CBA Boron 31.7 5.1 33.6 4.6 0.104 DOT Boron 68.8 5.0 65.1 5.5 0.004

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93 Borate MSWTCLPSPLPWET Concentration (mg/L) 020406080100120140160 Boron MSWTCLPSPLPWET Concentration (mg/L) 110100 ACQCu B MSWTCLPSPLPWET Concentration (mg/L) 0.1110100 As Cr Cu CCA TC-Limit for As and Cr CBA MSWTCLPSPLPWET Concentration (mg/L) 10100 Cu B Figure 4-1 Average preservative leaching wood products under several leaching environments (A) CCA, (B) ACQ, (C) CBA, (D) DOT (error bar represents standard deviation of three replicates for TCLP, SPLP and WET; for MSW leaching the error bar represents standard deviation of seventy eight samples (three replicate per leachate from twenty six sites)

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94 Sites 0510152025 Arsenic concentration (mg/L) 0246810121416 Average As TCLP concentration TCLP limit SPLP concentration (A) Sites 0510152025 Chromium concentration (mg/L) 02468 Average Cr TCLP concentration TCLP limit SPLP concentration (B) Figure 4-2 Arsenic and chromium leaching from CCA-treated wood samples leached with various landfill leachates as the leaching fluid (Error bars represent standard deviation among replicates), (A) Arsenic, (B) Chromium .

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95 Sites 0510152025 Boron concentration (mg/L) 5101520253035 Average concentration TCLP concentration SPLP concentration (A) ACQ Sites 0510152025 Boron concentration (mg/L) 1520253035404550 Average concentration TCLP concentration SPLP concentration (B) CBA Sites 0510152025 Boron concentration (mg/L) 5055606570758085 Average concentration TCLP concentration SPLP concentration (C) DOT Figure 4-3 Boron leaching from ACQ-, CBAand DOTtreated wood samples leached with various landfill leachates as the leaching fluid (Error bars represent standard deviation among replicates)

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96 Sites 0510152025 Copper concentration (mg/L) 0510152025 Average Cu TCLP concentration SPLP concentration CCA(A) Sites 0510152025 Copper concentration (mg/L) 0102030405060 Average Cu TCLP concentration SPLP concentration ACQ(B) Sites 0510152025 Copper concentration (mg/L) 020406080100120140 Average Cu TCLP concentration SPLP concentration CBA(C) Figure 4-4 Cu leaching from pressure treated wood samples leached with several landfill leachates as the leaching fluid (Error bars represent standard deviation among replicates) (A) CCA, (B) ACQ, and (C) CBA.

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97 Ammonia (mg/L) 0200400600800 Percent Copper Leached 010203040 CCA ACQ CBA R2=0.64 for CBAR2=0.43 for ACQR2=0.83 for CCA Figure 4-5 Cu concentrations in the extracts as a function of landfill leachate -ammonia

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CHAPTER 5 COMPARISON OF CCAAND ACQTREATED WOOD DISPOSAL IN CONSTRUCTION AND DEMOLITION DEBRIS LANDFILLS 5.1 Introduction The generation and widespread use of chromated copper arsenate (CCA-) treated wood products in the U.S. started in the 1970s. Since the service life of a typical CCA-treated wood product ranges from 15-30 years, large quantities of CCA-treated wood product have been disposed of in the last several years. It has been estimated that approximately 140,000 m 3 of CCA-treated wood product were disposed in Florida during the year 2000. This quantity is forecasted to increase to 900,000 m 3 by 2015 (Solo-Gabriele and Townsend, 1999). In a recent extensive study at one Florida C&D recycling facility, wood waste was found to contain an average 22% CCA-treated wood (Solo-Gabriele et al., 2004). In many states, including Florida, the majority of CCA-treated wood is disposed in construction and demolition debris (C&D) landfills. C&D debris landfills are not regulated specifically at the US federal level, and some states require bottom liner systems for these facilities while others do not (Clark et al., in-press). In states where C&D debris landfills must be lined, C&D debris is often co-disposed in lined municipal solid waste (MSW) landfills. An issue at lined landfills with respect to treated wood disposal is the impact on leachate quality. The potential for groundwater contamination is the primary concern at unlined C&D debris landfills. For both of these scenarios, the 98

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99 impact of elevated metal concentrations in leachates can raise questions regarding the appropriateness of disposing treated wood products in C&D debris landfills. As of January 2004, the treated wood industry phased out the use of CCA for most residential uses in favor of arsenic (As) and chromium (Cr) free preservatives. One of the most popular As and Cr free preservatives is the copper(Cu-) based alkaline copper quaternary (ACQ). ACQ currently makes its way into the C&D wood waste stream primarily as a construction scrap (Jacobi, 2005), but in the future it will enter as demolition debris (after hurricane Katrina, a considerable amount of ACQ-treated wood was observed as part of the wood waste in the C&D debris generated in Gulf coast). Several experiments have been conducted to assess the impact on leachate quality from the disposal of CCA-treated wood in the C&D debris landfill environment using simulated landfills (Weber et al., 2002; Jang and Townsend, 2003b; Jambeck, 2004). Another technique that has been used to assess the leaching behavior of treated wood in a landfill environment is to leach treated wood in landfill leachate as presented in detail in the Chapter 4 (Jang and Townsend 2003b, Townsend et al., 2004; Dubey et al, 2004). The objective of this chapter was to compare the impact of the disposal of CCAand ACQ-treated wood on leachate quality in a C&D debris landfill environment. Three lysimeters (simulated landfill columns) were used, one each simulating CCAand ACQ-treated wood disposal in a C&D debris landfill; a third lysimeter was included as a control with no pressure treated wood disposed in it. Treated wood blocks and drill shavings were leached using leachates collected from the control lysimeter. Two additional batch leaching tests were conducted, the synthetic precipitation leaching

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100 procedure (SPLP) (EPA Method 1312) and the toxicity characteristic leaching procedure (TCLP) (EPA Method 1311). 5.2 Material and Methods 5.2.1 Lysimeter Construction and Installation Lysimeters were constructed of high density polyethylene (HDPE) pipe, 0.6-meter (2-feet) in diameter and 5-meter (16-feet) long. A 7.5-centimeter (3-inch) diameter HDPE pipe was attached to the lysimeter and connected at the bottom for leachate sampling. A HDPE geonet was placed at the point of connection of the two pipes to prevent the drainage material (gravel) from entering the leachate collection pipe. A schematic and photographs of the lysimeters are included in Appendix D. The lysimeters were buried upright in 0.9-meter (3-feet) diameter bucket auger borings in the Polk County North Central landfill, Florida (a brief site detail is presented in Appendix D). One challenge with previous lysimeter studies was temperature control. Temperature influences both the microbiology and chemistry of the lysimeter. A lysimeter in a laboratory or outside environment will not maintain the temperature of a landfill, which is approximately 50C. Simulated C&D debris landfill experiment (conducted in the outside environment) by Jambeck (2004) saw a sharp decrease of sulfide production (approximately two orders of magnitude lower) when ambient temperature dropped by approximately 15C (from around 30C to 15C) during winter months. This issue was addressed in the present study by placing the entire lysimeter inside a landfill where the surrounding waste could moderate the temperature of simulated C&D debris in the lysimeter.

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101 5.2.2 Lysimeter Composition and Loading The composition of C&D debris used to fill the lysimeters was based on an EPA C&D debris characterization (US EPA, 1998) and previous C&D debris lysimeter studies (Jang and Townsend, 2003b; Jambeck, 2004). The waste components and their percentage, source and method of processing for the control lysimeter are presented in Table 5-1. For the CCA and ACQ lysimeters, part of the untreated wood was replaced with an equal weight of CCA-treated wood or ACQ-treated wood with a composition of 5% of the total weight of C&D debris (15% by weight of wood waste). The C&D debris components were size reduced and mixed prior to loading. Loading was performed in several lifts with each lift containing all the components of C&D debris in the same proportion (as per Table 5-1). After loading every lift, the waste was compacted by dropping a weighed plate repeatedly to achieve a density of approximately 450 kg/m 3 (see Figure D-4 of Appendix D). C&D debris mixing and loading photographs are included in Appendix D. 5.2.3 Determination of Total Extractable Metal Concentrations in Untreated and Treated Wood Total extractable As, Cu, Cr and boron (B) concentrations in the treated wood and untreated wood samples were obtained. The drill shavings were produced by drilling through treated wood blocks sampled from the set those used for the lysimeters. The ground pallet used for the untreated wood was further processed through a Fritsch Pulverisette 19 mill to a particle size less than 3 mm prior to analysis. For both treated and untreated wood, two grams of the sample were weighed and acid digested in five replicates following EPA, Method 3050B (US EPA, 2003) prior to analysis by

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102 inductively coupled plasma atomic emission spectroscopy (ICP-AES, Thermo Electron Corporation, Trace Analyzer) following EPA Method 6010B. 5.2.4 Lysimeter Monitoring, Water Addition and Sample Collection The results presented in this chapter covered a monitoring period of thirteen months for these lysimeters. The lysimeters are operational as of date and will be monitored further with possible air injection at the end of the monitoring period. Rainfall was simulated by adding de-chlorinated tap water at regular intervals. Water was distributed evenly on top of the lysimeter using coils of perforated tubes connected to a hose and bucket filled with water. The depth of leachate was measured in the side pipe of the lysimeter using a water sensor meter (Heron Instruments, Little Dipper). Leachate, if available, was pumped using a submersible pump from the 7.5-cm (3-inch) side pipe and samples were collected for various analyses in appropriate containers. The samples were transported to the lab on ice and preserved as appropriate. They were stored at 4 o C until analysis for various parameters as presented in detail later in this chapter. 5.2.5 Laboratory Batch Leaching Procedures For comparative purpose several batch leaching tests were conducted. Sub-samples of the CCAand ACQ-treated wood blocks (100 gm blocks) were leached in duplicate using the leachate collected from the control lysimeter on the 208 th day of lysimeter operation. The extraction procedure used for leaching with C&D debris control leachate was similar to TCLP. The leaching tests TCLP (EPA Method 1311) and SPLP (EPA Method 1312) were also conducted on these samples (US EPA, 2003). Drill shaving samples were also leached in triplicate using these three leaching procedures. The pH of the C&D control leachate used for the testing was 6.65. The TCLP solution was prepared by mixing appropriate volumes of 0.1 M glacial acetic acid with 1 N sodium hydroxide

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103 and diluting to 2-L using de-ionized water to achieve a pH of 4.93 0.05. The SPLP solution was prepared by mixing dilute sulfuric and nitric acid at a 40/60 weight ratio to achieve a pH of 4.200.05 (US EPA, 2003). After mixing on a rotary extractor, samples were filtered using a pressurized filtration apparatus with a 0.7-m borosilicate glass fiber filter (Environmental Express TCLP filter). The filtrate was preserved with concentrated nitric acid (pH < 2.0) and analyzed. 5.2.6 Leachate Analysis Leachate sample collected from the columns were characterized for typical leachate quality parameters, including metals, sulfides, alkalinity, total dissolved solids (TDS), and chemical oxygen demand (COD). EPA methods (US EPA, 2003) and other standard methods (APHA, 1995) were employed when applicable. Heavy metal concentrations in the simulated landfill leachates as well as the batch leaching leachates were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES Thermo Electron Corporation, Trace Analyzer, EPA Method 6010B) after digesting the aqueous leachate samples following EPA Method 3010A (US EPA, 2003). The detection limits for As, Cu, Cr and B were 12g/L, 4g/L, 4g/L and 6g/L, respectively. Laboratory blanks, matrix spikes, and calibration checks were performed when appropriate for analysis for quality assurance/quality control (QA/QC). Analysis of blank samples were consistently below detection limits, matrix spike samples and calibration check samples showed recoveries between 90 and 107%. 5.3 Results and Discussion 5.3.1 Total Metal Content in the Co-Disposed Wood Waste The rated retention for CCA and ACQ wood used for the wood waste component was 4 kg/m 3 . On analysis it was found that the CCA treated wood sample contained

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104 1710 93 mg-As/kg, 1890 150 mg-Cr/kg and 1130 78 mg-Cu/kg. Cu and B concentrations in the ACQ treated wood samples were 3750 125 mg-Cu/kg and 510 35 mg-B/kg, respectively. The total Cu concentrations measured for the CCAand ACQtreated wood samples were similar in magnitude as measured for 4 kg/m 3 rated retention CCA and ACQ samples used by Townsend et al. (2003c). Lysimeter leachate analysis (as presented in section 5.3.3. below) found As and Cr concentrations above the detection limit in leachates from both the C&D control lysimeter and the CCA and ACQ lysimeters. The untreated wood used for the simulated C&D debris was found to be the source of As and Cr, as it contained 49.5 5.3 mg/kg of As (arithmetic mean of five replicates corresponding standard deviation), 63.0 5.5 mg/kg of Cr, 28.6 2.1 mg/kg of Cu and 6.5 1.2 mg/kg of B. These concentrations suggest that the untreated wood waste contained approximately 3% CCA-treated wood. The untreated wood was collected from a local transfer station also collecting wood waste for recycling. Previous research has shown that CCA-treated wood does get inadvertently mixed with other wood waste in a C&D debris recycling facility (Tolaymat et al., 2000; Townsend et al., 2003a; Solo-Gabriele et al., 2004; Jacobi, 2005). 5.3.2 Temporal Variation of Leachate Parameters Figure 5-1 presents the amount of water added and leachate produced over time from the three simulated C&D lysimeters. In general, the rate of leachate production followed the trend of water addition into the lysimeters. The ACQ lysimeter produced more leachate throughout the duration of the experiment. This occurred because of temporary flooding on top of the lysimeter during heavy storms, as this lysimeter was

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105 located at a slightly lower elevation compared to the other two. The control and CCA lysimeters followed very similar trends in terms of leachate production. . Leachate pH, ORP (Figure 5-2), and conductivity (Figure 5-3) from the control, CCA and ACQ lysimeters are presented as a function of time. The pH ranged between 6.2 and 7.0 throughout the experiment. This pH range is typical for C&D debris leachate and follows trends reported in previous studies (Weber et al., 2002; Jang and Townsend, 2003b; Jambeck, 2004). The ORP values (-350 to -450 mV) for the three lysimeters were within the range reported by previous studies (Jang 2000, Jambeck 2004). The ORP value observed in this experiment fell in the range of the anaerobic, sulfate reducing phase of a C&D debris landfill as described by Jang (2000). Conductivity measures the dissolved ions in solution. With CCAand ACQtreated wood contributing more ions to solution, higher conductivity values were observed in these leachates compare to control. Temperature readings were collected from thermocouple wires at different depths next to the lysimeters. The temperature ranged from approximately 30C (ranged from 28.9C to 35.5C) at 2.6 feet from the top of the lysimeters to about 45C (ranged from 44.3C to 48.5C) at the bottom of the lysimeters throughout the duration of the experiment. In previous lysimeter studies (Jambeck, 2004), the temperature of the leachate changed drastically with ambient conditions. This was prevented in this study by burying the lysimeters inside the landfill o o o o o o . Figure 5-4 through Figure 5-6 presents other leachate parameters over time including COD, sulfides, TDS, alkalinity and sulfate. Gypsum drywall (CaSO 4 2H 2 O) present in C&D debris is dissociated in aqueous solution producing sulfate. The sulfate

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106 reducing bacteria (SRB) then reduce sulfate (oxidizing the organic matter) producing hydrogen sulfide as per following equations (Bitton, 2005): 2CO O2H -2S matter organic 24SO (1) S2 H 2H -2S (2) In this reaction organic matter acts as an electron donor and the sulfate is the electron acceptor. Sulfide concentrations for the three lysimeters varied between 100 mg/L to 300 mg/L for most of the experiment. The variation of sulfide concentration was less prominent in this experiment compared to the one observed in previous studies as 0.17 to 84 mg/L (Jambeck, 2004) and 0 to 37 mg/L (Jang, 2000). Less variation in temperature (an important parameter affecting SRB activity) could be one of the reasons for this observation. The COD values for the three lysimeters are presented in Figure 5-4. Comparing the CCA lysimeter COD values (range 2000 to 5000mg/L) with previous studies, it was found that this value was higher than the reported values earlier of 720 to 2170 mg/L (Jambeck, 2004) and 90 to 630 mg/L (Jang, 2000). In general, for most of the leachate parameters evaluated, the values observed in this study were higher compared to previous studies of Jang (2000) and Jambeck (2004). This is possibily due to relatively higher waste density in the present simulated landfill study. Comparatively higher COD in the ACQ lysimeter could be due to the additional contribution of amine leaching from ACQ treated wood (Stumm and Morgan, 1996). TDS concentrations in the three leachates followed the trend of the conductivities of the leachates. TDS and alkalinity concentrations in the CCA lysimeter were slightly higher than observed by previous studies (Jambeck, 2004; Jang, 2000). The ACQ lysimeter had more alkalinity compared

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107 to the CCA and control lysimeters. This could be due to the presence of high levels of borates leaching from the ACQ treated wood in the ACQ lysimeter as presented in the next section (Stumm and Morgan, 1996). Figure 5-6 presents the sulfate concentrations in the leachates from the three lysimeters over time. The sulfate concentration measured was in the same range as observed by Jang, 2000. 5.3.3 Arsenic, Chromium, Boron and Copper Leaching Over Time Figures 5-7, through 5-9 present the As, Cr and B concentrations for the three lysimeters for the duration of the experiment. The As concentrations (Figure 5-7) from the CCA lysimeter were found to be significantly (‘t’ test with unequal variance, = 0.01, P < 10 -6 ) elevated compared to the control and ACQ lysimeters. The As concentration reached its peak of approximately 1.2 mg/L and then gradually decreased over time. The As concentration in the last sample was slightly above 0.5 mg/L which is 10 times higher than the present drinking water standard of 50g/L and 50 times higher than the new drinking water limit of 10 g/L (will be effective on Jan 1, 2006). Arsenic was also detected in the control and ACQ lysimeter leachates with concentrations measuring in the range of approximately 0.3 mg/L in the beginning to 50 g/L towards the end of the monitoring period of the lysimeters. The presence of CCA-treated wood in the untreated wood waste component resulted in elevated As concentrations in control and ACQ lysimeters. Comparing the As concentrations in the CCA lysimeter leachate to the values observed in previous studies, it was observed that the As concentrations measured in this present study were higher than values reported by Jang, (2000) (0.01mg/L to 0.38mg/L) and were lower than values reported by Jambeck, (2004) (1.09 mg/L to 4.25mg/L). This was not unexpected, as the amount of CCA-treated wood disposed in the present study was 5% by weight of the total C&D debris;

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108 while Jang (2000) and Jambeck (2004) had 0.5% and 10.2% of CCA-treated wood in their experimental lysimeters respectively. The Cr concentrations (see Figure 5-8) in the CCA lysimeter were significantly elevated (‘t’ test, unequal variance, = 0.01, P < 10 -8 ) in comparison to the control and ACQ lysimeters. The Cr concentration in the CCA leachate was higher than the drinking water limit of 100g/L for the first 6 months of the experiment. The Cr concentration in control and ACQ lysimeters followed a similar pattern with significant levels of Cr observed in both leachates. This again could be the contribution of CCA contaminated untreated wood as explained in the previous paragraph for As. Comparison to the previous studies (Jambeck, 2004 (0.3 to 2.1mg/L); Jang, 2000 (0.07 to 0.17mg/L)) found that the Cr concentration followed the same patterns as noted for As. Copper concentrations throughout the duration of the experiment were below the detection limit (4 g/L) in all three lysimeters. Sulfide was produced on reduction of sulfate as presented in equation (1) as discussed in section 5.3.2. Copper being a chalcophile element has highest affinity for sulfide to make stable insoluble complexes of CuS as per following equation: CuS -2S 2Cu Stability constant of 25.9 (Benjamin, 2001) (3) The C&D lysimeters in this study had a steady sulfide concentration throughout the duration of the experiment (no SRB inhibition due to temperature fluctuation observed in the present study). Cu is expected to precipitate as CuS in the pH and ORP conditions observed in the present experiment. The observation here follows the trend observed in previous experiments (Jambeck, 2004; Weber, 2002; Jang, 2000) suggesting that Cu precipitates as a sulfide mineral in the strongly reducing, sulfide-rich environment.

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109 Figure 5-9 presents the concentration of B in the leachates. B concentrations were significantly elevated (‘t’ test, unequal variance, = 0.01, P < 10 -5 ) in the ACQ lysimeter (ACQ does contain some B); B was also detected in the control and the CCA lysimeters indicating that some other source of boron in C&D debris is present. The B concentrations in the ACQ leachate were approximately 10 mg/L in the initial leachate samples which reduced to approximately 2 mg/L at the end of the experiment. The concentrations of B from the control and CCA lysimeters were similar to the concentrations from ACQ lysimeter towards the end of the experiment, which suggests that there were other sources of boron in the C&D debris. Assuming all the B leaching in ACQ lysimeter is coming from ACQ treated wood, it was found that 30.2% of B initially present leached out during the experimental duration. 5.3.4 Batch Leaching Test Results for As, Cr, Cu and B Figure 5-10 presents the results of the batch leaching tests conducted on the 100-g blocks as well as the drill shavings of CCA-treated wood. The final pH of the extracted solution for each sample is also presented on the figure. For the CCA block samples, the lowest final pH was recorded for the SPLP extraction (pH= 4.62). The TCLP and C&D leachate final pH was 4.98 and 6.45 respectively. The As concentrations for both the CCA blocks and drill shavings followed the pattern of TCLP > SPLP >C&D leachate, however, the As concentrations from the drill shavings were almost five times higher than the concentrations from the CCA blocks. Similar trends were observed with the CCA-treated wood sawdust sample when leached with TCLP, SPLP and a simulated C&D control leachate (Townsend et al., 2004). Arsenic, Cu and Cr concentrations from drill shavings samples using TCLP and SPLP were observed to be in a similar range as observed in previous studies (Townsend

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110 et al., 2004; Stook et al., 2005). The CCA block samples also leached similar concentration of As, Cr and Cu as observed in a previous study (Townsend et al., 2004). The As concentration in the CCA block C&D leachate was 1.12 mg/L, which was similar to the As concentration observed in the CCA lysimeter after approximately 200 days of leachate monitoring (the batch leaching was carried out with the C&D control leachate collected during this period). The As and Cr concentration in the CCA lysimeter varied from 0.5 mg-As/L to 1.2 mg-As/L, and 0.1mg-Cr/L to 0.2mg-Cr/L. Comparing the maximum As and Cr concentration in CCA lysimeter with block TCLP and SPLP concentrations, it was found that TCLP and SPLP over predicted the maximum concentration in simulated landfill by a factor of 1.51 and 1.43 respectively for As, and 1.35 for Cr (both SPLP and TCLP). SPLP has been equated to represent a C&D debris landfill environment (FR 63-243, 1998). The concentration of As and Cr measured in SPLP were 43% and 35% higher than the maximum concentration measured in the CCA lysimeter. This again reconfirms the fact that batch leaching tests are a useful screening tool to evaluate potential leaching issues with a particular waste when disposed in a landfill. In general, the C&D debris landfill leachate resulted in concentrations of the three CCA elements in the same magnitude as the TCLP and SPLP, though the TCLP concentrations were the greatest. Copper leaching is generally enhanced in the TCLP as a result of the ability of copper to complex with the acetic acid in the TCLP solution (Townsend et al., 2004). As mentioned in the previous section, Cu was below the detection limit for all the lysimeter leachate samples. During the batch leaching with the C&D leachate a low amounts of Cu (0.23mg/L) were observed with the CCA block sample as shown in Figure

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111 5-10. The Cu in C&D lysimeters are hypothesized to precipitate as CuS in the reducing conditions as per equation (3) presented in previous section. The sulfide concentration in the control leachate used for leaching test was 330mg/L. Based on this sulfide concentration and the solubility product (K sp ) of CuS, Cu concentration was calculated (detailed calculation presented in Appendix D). It was found that Cu should be below the ICP detection limit (<4 g/L). However low concentrations of Cu was detected in these samples. One of the possible reasons could be partial conversion of sulfide to sulfate while setting up the leaching test and also during the experimental period due to the headspace in the leaching containers. Figure 5-11 presents copper and boron leaching from ACQ-treated wood samples using the three leaching solutions formerly mentioned. Although boron leached similar concentrations for all of the solutions, copper leaching varied dramatically among the leaching solutions. As was the case with CCA, copper leaching was greater with the TCLP relative to the SPLP. Concentrations measured from the C&D leachate test, however, were much lower than the SPLP. Comparing the Cu concentrations leached in C&D leachate from the CCA and ACQ block samples it was found that CCA leached 0.23mg/L while ACQ leached 0.33mg/L. For the drill shavings samples, CCA leached 2.11mg/L and ACQ leached 0.54 mg/L of Cu. The final pH of the CCA and ACQ block C&D leachates were similar and the pH was lower for CCA drill shavings C&D leachate (pH = 5.96) compared to ACQ (pH = 6.20). Comparatively, the lower final pH of the CCA sample could have impacted the Cu leaching from the CCA drill shavings samples. When CCA sawdust samples were leached over a range of pH values, it was found that there was low variation in Cu concentration in the leachate when pH of the extraction

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112 solution was varied from pH=5 to pH=8 (Townsend et al., 2004). In the case of ACQ sawdust samples (part of another experiment, see Appendix A for details) leached over pH range of 5 through 8, the Cu concentration in the leachate decreased to 27 mg/L at pH=8 compared to 41mg/L at pH=4.8. Considerable difference between SPLP and C&D leachate Cu concentrations for ACQ samples compared to CCA could be due to this pH effect on Cu concentration in ACQ leachates. The B concentration from the block samples were 3.9, 3.2, 3.7 mg/L respectively for TCLP, SPLP and C&D control leachate. The maximum B concentration in C&D ACQ lysimeter was 12 mg/L during the early phase of the experiment (lower liquid-to-solid ratio). Unlike As, Cr and Cu from CCA-treated wood, TCLP and SPLP concentrations under predicted the B leachate concentrations in the ACQ lysimeter leachate. Other studies have shown (Townsend et al., 2006), that batch leaching tests such as SPLP do not always predict the highest concentration (pore water concentration) of an element leached from a waste. 5.4 Implication for Management The As and Cr concentrations in the CCA lysimeter and the B concentration in the ACQ lysimeters were elevated compared to the control lysimeter. Cu concentrations were below detection in all three lysimeters, indicating that Cu leaching would not be a concern in a reducing C&D landfill environment when Cu treated wood is disposed in a C&D debris landfill. The majority of Cu is precipitated as CuS under these conditions and rendered immobile. In chapter 4, higher concentrations of Cu leached when treated wood was leached with MSW landfill leachate as the leaching fluid. However, under the reducing lysimeter conditions, as observed in this chapter, most of the Cu is precipitated in the simulated landfill itself and not present in the leachate. The results indicate that Cu leaching on disposal of ACQ treated wood in C&D debris landfill will not be a concern

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113 as long as anaerobic conditions are maintained. However, over an extended period of time if the air makes some intrusion into a C&D landfill, Cu may come back in to solution. Further research is needed to evaluate this phenomenon. Arsenic and Cr leaching at elevated levels (above its drinking water limit of 0.05mg/L and 0.1 mg/L respectively) could be a concern for CCA-treated wood disposal in unlined C&D landfills. The concentrations observed in this study reconfirms the observation made by Jang (2000) and Jambeck (2004) who found elevated As concentrations in experimental lysimeters compared to controls when CCA-treated wood is disposed with simulated C&D debris. Five percent (of total weight) of CCA-treated wood was disposed in CCA lysimeter in the present study, Jang (2000) and Jambeck (2004) had 0.5% and 10% of CCA-treated wood in their experimental lysimeters, respectively. Figure 5-12 presents a box plot of As concentrations in the CCA lysimeter leachate from these three studies. Arsenic concentrations were significantly different with lower concentrations measured in the CCA lysimeter leachates with lower percentages of CCA-treated wood disposed within them. More As was observed as % disposed CCA-treated wood was increased in different experiments. The As concentration in the leachates from Jang (2000) also exceeded the new drinking water standard of 10 g/L throughout the duration of the experiment. This indicates that elevated As concentration would be a concern even with a very low percentage (Jang, (2000) had 0.5% CCA by weight) of CCA-treated wood disposed of in a C&D debris environment. C&D landfills in 27 states (Clark et al. – in press) are unlined, the concentrations of As and Cr observed in the leachates in the present and previous studies (Jambeck, 2004; Jang, 2000) would suggest close monitoring of the groundwater wells

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114 surrounding these C&D landfills. The C&D landfill groundwater monitoring data as of date does not show widespread As or Cr contamination (Jambeck, 2004). This could be either due to dilution and attenuation in the soil below C&D landfills or it may be that As and Cr have not traveled far enough to reach the monitoring groundwater wells. Boron concentrations in the leachate for all the three lysimeters were above the ground water clean target level (GWCTL) of 630 g/L for the duration of the experiment indicating potential groundwater contamination from B following disposal of ACQ treated wood in an unlined C&D landfill. When the percentage leaching was calculated, it was found that 0.82% of the As and 0.11% of Cr present in the CCA lysimeter waste components leached over the duration of the experiment. For the ACQ column, 30.2% of B initially present in waste components leached over the duration of the experiment if all the B is assumed to be coming from the ACQ-treated wood. Other sources of B may be present in the other C&D debris components, identifying the sources would require further exploration. As discussed and presented in previous chapters DOT treated wood was found to leach higher concentrations of B when exposed in natural conditions (deck runoff) or when leached with various batch leaching tests (in Chapter 4). The disposal of DOT treated wood in C&D debris landfill could be a potential concern for boron leaching. 5.5 Summary To summarize, with respect to landfill disposal, elevated As and Cr leaching from CCA-treated wood would be a concern for groundwater contamination in an unlined landfill. Similar observations were made by Jambeck (2004) and Jang (2000). The result from this study reconfirms the observation made in these previous studies. For lined landfills, elevated concentrations would have impacts on leachate treatment and

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115 management. Some landfills in Florida are already facing the problem of elevated As concentrations in their leachates. Source of the elevated As has not been determined at this moment. With lowering of DW limit for As to 10g/L from 50g/L, potential high concentrations of As in leachates would be a major concern for a landfill operator. Copper leaching is not an issue as Cu is potentially precipitated as CuS within the landfill and hence not mobile under anaerobic conditions. High B leaching (both percentage and concentration) would be a concern for groundwater contamination and leachate management when ACQ treated wood is disposed in a landfill in substantial quantities.

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116 Table 5-1 Waste composition of C&D simulated lysimeters Waste Components Percentage in Control Lysimeter Source and Processing (if any) Untreated wood 33.6 #1 Ground pallets from local transfer station Concrete 29.3 Local concrete recycling facility (2-3 inch material) Roofing 13.7 Discarded load of scrap roofing material from a construction contractor, ground using Packer 2000 Drywall 12.4 New drywall scrap from a construction contractor, grounded using Packer 2000 Cardboard 8 Local Material Recycling Facility (MRF), bale of cardboard shredded using Packer 2000 Aluminum cans 0.6 Aluminum cans from the MRF at the landfill Copper wire 0.6 Copper wire from a local private recycler Insulation 0.6 Insulation from onsite renovation at landfill Steel bar 0.6 Rebar from landfill metal shop Steel sheet 0.6 From a local recycler, reduced to approximately 10 cm X 10 cm size mechanically #1 The untreated wood percentage was reduced to 23.6% for the two experimental C&D lysimeters. The difference of 10% was compensated by adding 5% treated wood (CCA or ACQ) and 5% lead based paint wood (in both).

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117 0100200300400 Water Addition and Leachate Production (Litres) 02004006008001000 C&D Control Water added C&D Control Leachate C&D CCA Water added C&D CCA Leachate C&D ACQ Water added C&D ACQ Leachate Days of Lysimeter Monitoring Figure 5-1 Water addition/leachate production for simulated C&D landfills over time

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118 0100200300400 pH 5.05.56.06.57.07.58.0 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring 0100200300400 ORP -500-450-400-350-300 C&D Control C&D CCA C&D ACQ Days of Lysimeter Montoring Figure 5-2 pH and ORP of leachate over time from simulated C&D landfills

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119 0100200300400 Conductivity (mS/cm) 024681012 C&D Control C&D CCA C&D-ACQ Days of Lysimeter Monitoring Figure 5-3 Conductivity of leachate over time from simulated C&D landfills

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120 0100200300400 COD (mg/L) 0200040006000800010000120001400016000 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring 0100200300400 Sulfides (mg/L) 0100200300400500 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Figure 5-4 COD and sulfide of leachate over time from simulated C&D landfills

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121 0100200300400 TDS (mg/L) 2000400060008000100001200014000 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Days of Lysimeter Monitoring 0100200300400 Alkalinity (mg/L) 10001500200025003000350040004500 C&D Control C&D CCA C&D ACQ Figure 5-5 TDS and alkalinity of leachate over time from simulated C&D landfills

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122 0100200300400 Sulfates (mg/L) 020040060080010001200 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Figure 5-6 Sulfate concentration of leachate over time from simulated C&D landfills

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123 100200300400 Arsenic (mg/L) 0.00.20.40.60.81.01.21.4 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Figure 5-7 Arsenic concentrations in the leachates from three lysimeters over time 100200300400 Chromium (mg/L) 0.000.050.100.150.200.25 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Figure 5-8 Chromium concentrations in the leachates from three lysimeters over time

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124 100200300400 Boron (mg/L) 02468101214 C&D Control C&D CCA C&D ACQ Days of Lysimeter Monitoring Figure 5-9 Boron concentrations in the leachates from three lysimeters over time

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125 TCLPSPLPC&D Leachate Concentration (mg/L) 0.00.20.40.60.81.01.21.41.61.82.0 100 gm Blocks4.98Final pH4.626.45 Drill Shavings TCLPSPLPC&D Leachate 02468101214 Concentration (mg/L)4.90Final pH4.475.96Arsenic Copper Chromium Figure 5-10 Preservative leaching from CCA-treated wood under batch leaching tests of TCLP, SPLP and leaching with a C&D debris landfill leachate (Average concentrations reported for duplicate block samples and triplicate drill shavings samples, error bars represent standard deviation for triplicate drill shavings leachates)

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126 TCLPSPLPC&D Leachate 0102030405060 Drill ShavingsCopper Boron 5.025.126.20Final pH 100 gm Blocks TCLPSPLPC&D Leachate 0246810 4.975.166.40Final pH Figure 5-11. Copper and Boron leaching from ACQ-treated wood under batch leaching tests of SPLP, TCLP and with a C&D debris landfill leachate. (Average concentrations reported for duplicate block samples and triplicate drill shavings samples; error bars represent standard deviation for triplicate drill shavings leachates)

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127 Jang (2000) Arsenic (mg/L) 012345 Dubey (2005)Jambeck (2004)(0.5%CCA)(5%CCA)(10%CCA) Figure 5-12. Arsenic concentration in CCA lysimeter leachates from three C&D lysimeter projects

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CHAPTER 6 SUMMARY AND CONCLUSION 6.1 Summary Treated wood is a major construction material in the United States. Most wood species receive treatment to enhance their service life especially in hot and humid weather conditions such as in Florida. Until recently, chromated copper arsenate (CCA-) was the most popular wood preservative. Human health and environmental concerns related to arsenic (As) and chromium (Cr) in CCA prompted the wood preservation industry to voluntary withdraw CCA in favor of Asand Cr-free preservatives for most residential applications. The wood preservatives available on the market as replacements to CCA include alkaline copper quaternary (ACQ), copper boron azole (CBA), and borate-based preservatives such as disodium octaborate tetrahydrate (DOT). Substantial research has been performed evaluating environmental impacts of CCA-treated wood in different use and disposal scenarios in recent decades. Minimal similar research is available evaluating the new Cu-or B-based alternative treated wood products. In this dissertation, research was performed to understand the potential environmental impact of these new alternatives under different environmental scenarios and to compare their impacts to that from CCA-treated wood under similar conditions. Four major experiments were performed. The impact of surface water conditions on chemical leaching and aquatic toxicity of leached chemicals from different pressure-treated wood products were studied as part of the first experiment. The leaching of Cu from treated wood blocks of CCA-, ACQand CBA-treated wood was found to be 128

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129 affected by surface water chemistry, especially pH and the presence of inorganic and organic ligands. A very small fraction of total Cu was measured as labile Cu. Labile Cu concentrations correlated with MetPLATE aquatic toxicity better than total Cu concentrations. Toxicity was reduced in the treated wood leachates with natural water compared with DI and MHW. Treated wood leachate created using the natural water as leaching solution exhibited higher toxicity for the water showing lower heavy metal binding capacity. In a second experiment the relative risk of treated wood products was compared using a deck and soil column experiment. In terms of direct exposure, As from CCA-treated wood was found to have higher relative risk compared to Cu; boron (B) and organic biocides present in alternatives. Concentration of organic biocides such as DDAC and tebuconazole were of relatively lesser concern in comparison to Cu concentrations in ACQand CBA-treated wood structure. In terms of potential groundwater contamination, B from DOT and As from CCA was found to have higher relative risk compared to Cu and organic biocides from ACQ and CBA. The potential impact of treated wood products on leachate quality of an MSW landfill was studied by leaching CCA-, ACQ-, CBAand DOT-treated wood products with 26 different landfill leachates along with TCLP, SPLP and WET procedure. Leaching of preservative components was found to be influenced by landfill leachate chemistry. Similar As concentrations were measured under TCLP and MSW landfill leachate leaching from CCA-treated wood unlike what has been reported in literature with few other types of As-waste. Copper leaching from CCA-, ACQand CBA-treated

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130 wood was similar in magnitude when leached with landfill leachate compared to TCLP and SPLP Cu concentrations. The fourth experiment compared the leachate quality of two simulated C&D debris landfills, one containing CCAand the other ACQ-treated wood. With respect to C&D debris landfill disposal, this study reconfirmed the earlier observation made by Jambeck (2004) and Jang (2000) that elevated As and Cr leaching from CCA-treated wood can pose a concern for groundwater contamination at unlined landfills. For lined landfills, elevated concentrations would have an impact on leachate treatment and management. Copper leaching was not found to be an issue as Cu is potentially precipitated as CuS within the landfill and was not mobile. High B leaching (both percentage and concentration) was found to be a concern for groundwater contamination and leachate management when ACQ-treated wood is disposed in a landfill in substantial quantities. 6.2 Conclusion The four experiments described in detail in previous chapters, as part of this PhD dissertation, compared the potential environmental impact from CCA-, ACQ-, CBAand DOT-treated wood under several use and disposal scenarios. The following specific conclusions were reached: A very small fraction of total Cu was available as labile Cu. Labile Cu concentrations correlated with MetPLATE aquatic toxicity better than the total Cu concentration. Surface water chemistry of natural waters affected Cu leaching from wood blocks of CCA-, ACQand CBA-treated wood. Natural water exhibiting higher heavy metal binding capacity showed lower toxicity in the leachate produced on leaching of treated wood blocks in these waters. Arsenic leaching from CCA-treated wood structure and subsequent build up of As on surface soil layer was found to be the most limiting in terms of exceeding the regulatory limits for all the treated wood products.

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131 Higher Cu leaching from ACQ-, CBAand B from DOT-treated wood products were also a concern in terms of risk analysis with concentrations in deck runoff and soil column eluents exceeding the regulatory limits for the most part of the experiment. Concentration of organic biocides, DDAC and tebuconazole were of relatively lesser concern in comparison to Cu concentrations in ACQ and CBA treated wood structure. Leaching of preservative components was influenced by MSW landfill leachate chemistry. In general, preservative leaching was not under predicted with TCLP as compared to concentrations observed from leaching with MSW landfill leachate. Elevated preservative concentrations could pose a concern for leachate treatment and management if treated wood products are disposed in substantial quantity in a MSW landfill. Elevated Cu concentration could be a concern when Cu containing treated wood is disposed in an anaerobic MSW bioreactor landfill in substantial quantities. Ammonia build up in the leachate could help bring more Cu in solution. As stated from previous research, this experiment reconfirms that elevated As and Cr leaching from CCA-treated wood would be a concern for groundwater contamination in an unlined C&D debris landfill. Copper leaching was not found to be an issue in a C&D debris landfill as Cu got precipitated as CuS within the landfill and was not mobile. High B leaching (both percentage and concentration) was found to be a concern for groundwater contamination and leachate management when ACQ treated wood is disposed in a landfill in substantial quantities. 6.3 Future Work The results from this PhD research will help understand and compare the environmental impact from various treated wood products under similar use and disposal conditions. In terms of impact of natural water conditions on preservative concentrations in the water, a future experiment could be to evaluate the effect of constant mixing and dilution of leached chemical from treated wood products that would occur in a natural water body as the new water flows into the system. In terms of landfill disposal, additional research should be conducted evaluating the impact on leachate quality at actual disposal sites and also simulating landfill experiments which are operated as an aerobic and anaerobic bioreactors. An interesting follow-up research would be to

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132 evaluate different absorbent layers for As at the bottom of an unlined landfill (e.g., a C&D debris landfill) which will help transform As in a form which is not leachable. Economics of the absorbent layer with conventional liner system would need to be evaluated.

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APPENDIX A ADDITIONAL SURFACE WATER STUDY DATA A.1 Leaching Solution Collection and Leaching Setup Lake Okeechobee (LO) Lake Alice (LA) St. Johns River (SJR) Atlantic Ocean (AO) Lake Wauberg (LW) Kissimmee River (KR) Wetland-1 Wetland-2 Lake Okeechobee (LO) Lake Okeechobee (LO) Lake Alice (LA) St. Johns River (SJR) Atlantic Ocean (AO) Lake Wauberg (LW) Kissimmee River (KR) Wetland-1 Wetland-2 Lake Alice (LA) St. Johns River (SJR) Atlantic Ocean (AO) Lake Wauberg (LW) Kissimmee River (KR) Wetland-1 Wetland-2 Figure A-1 Sampling locations for surface water samples collected for leaching solutions used in the study Figure A-2 A typical leaching setup for the treated wood blocks 133

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134 A.2 Detailed Procedure for Analysis A.2.1 Labile Cu Measurement Labile Cu was measured in the treated wood leachate using the Cu 2+ ion-selective electrode (ISE) (Orion 94-29) and double junction reference electrode (Orion 90-02). Detailed stepwise analysis procedure has been included in this section. 1. The ISE and the reference electrode were filled with appropriate filling solutions. 2. 100mL of DI water was placed in a 150mL beaker; 2mL ion strength adjuster solution (ISA, Orion 940011) was added to it. 1mL of 0.1M Cu standard was added to the beaker and the mV reading was recorded when the reading was stable (after approximately 60 sec). 10mL of the 0.1M standard was again added to the same beaker and stable mV reading was recorded. The difference between the two readings was calculated. This difference is called the slope of the electrode which was found to be in the range (+) 25-30 mV/decade under normal room temperature of 20-25C as desired to insure proper functioning of the electrode. 3. Low level measurement technique as presented in the ISE instruction manual was used for the analysis. This technique is recommended for free Cu concentrations less than 0.6 ppm. 4. Calibration curve was obtained by adding Cu standard at different levels to a DI water solution, pH of the DI Cu standard solution was lowered to pH<4 using few drops of 0.1N HNO 3 solution. 2mL of ISA solution was added and the corresponding mV reading was recorded when the meter was stable. A typical calibration curve is included as Figure A-3. 5. Treated wood samples were analyzed at pH 4 along the similar line as was done for the standards, as described in item #4. Standard Cu concentrationmV Reading ppm0.0011160.01144.10.064168.70.6985193.46.35222.6 calibration curvey = 11.945Ln(x) + 199.71R2 = 0.99751301501701902102300.1110concentration std cupric ion soln(ppm)measurement mV Figure A-3 Calibration curve for labile cu measurement in treated wood leachates

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135 A.2.1 MetPLATE Procedure The MetPLATE TM acute heavy metal bioassay is a short-term microbial assay that is unresponsive to organic toxicants to extreme concentrations, and thus, specific for heavy metals (Bitton et al., 1994). The assay is based on inhibition of -galactosidase in an mutant strain of E. coli induced to produce a copious amount of the enzyme. A chromogenic substrate, chlorophenol-red -galactopyranoside (CPRG), is used to quantify the enzyme activity. In the presence of the active enzyme, CPRG is cleaved, changing from yellow to red-purple. The extent of substrate conversion is quantified by measuring absorbance at 570nm. MetPLATE TM test kits are prepared at the University of Florida, Dept. of Environmental Engineering, and Laboratory for Environmental Toxicology and Microbiology. Kits consist of freeze-dried bacterial reagent, positive control, chromogenic substrate, buffer, diluent, and 96-well micro plate. A 0.9mL of diluent are placed in small culture tubes. Serial dilutions of leachates are prepared by adding 0.9mL of leachate to 0.9mL of diluent. Diluent-leachate mixtures are briefly vortexed, and 0.9mL of these mixtures are passed to 0.9mL of diluent to make the next dilution and the process is repeated until the final dilution is made. The 0.9mL of the final dilution is discarded with 0.9mL remaining in the tube. Usually 6 dilutions are prepared in triplicate. Six tubes, three containing 0.9mL negative control (diluent) and three with 0.9mL of positive controls are prepared. The bacterial reagent is rehydrated with 5mL of diluent and 0.1mL of the reagent is added to the dilutions and controls. For colored samples, background dilutions are prepared in the same manner as test dilutions, but 0.1mL of diluent is added instead of the bacterial reagent. All test tubes are vortexed briefly and placed at 35 o C dark incubator

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136 for 90 minutes. After incubations, 0.2mL of each test tube (sample dilution, absorbance background dilutions, and controls) is transferred to the microplate. Freeze-dried chromogenic substrate is rehydrated with 10mL of the buffer, and 0.1mL of substrate is added to each well of the microplate. Microplates are shaken for approx. 1 minute and returned to the incubator. After about 20-30 min., color changes are monitored and absorbance is periodically checked by a microplate spectrophotometer (Molecular Devices, kinetic microplate reader) at 570nm. The test is complete when absorbance in the negative control reached approximately 2. The leachate concentration was plotted on a logarithmic scale versus the percent of the effect observed. In this case the effect was measured as a color change in the test solution. This color change was measured in units of absorbance. The “percent effect” was thus computed from the equation A-1. A linear interpolation technique was then used to determine the concentration of the sample that resulted in a 50% decrease in absorbance (EC 50 ) which is related to the enzyme activity observed in the test. Figure A-4 illustrates the computation procedure. %100*absorbance control negativeabsorbance sample -absorbance control negative Effect % (A-1) A.2.2 Assessing Cu Binding Capacity of Different Surface Waters HMBC quantifies the decrease in heavy metal bioavailability and thus toxicity in aquatic environments, and is dependent on physico-chemical parameters such as pH, alkalinity, hardness, and the presence of complexing ligands (Huang et al., 1999). The HMBC concept is similar to the water effect ratio (WER) previously proposed by USEPA (USEPA, 1984), with both techniques recognizing the significant relationship between site-specific water quality parameters and heavy metal bioavailability.

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137 01020304050607080901000.010.1110Concentration (mg/l or percent v/v)% Effect Low concentrationsshow no effect High Concentrationsshow 100% effect Equation of Best FitLine in Linear Rangeof Curve:% Effect = X (Concentration) + YX = slope of lineY = Y intercept of line EC50 is theconcentrationat which 50%of the effect is encountered Figure A-4 Method for computing EC50 (From Townsend et al., 2003c) For HMBC calculation for a particular element, the general practice is to spike a standard solution of the particular metal being studied as done in the previous studies (Huang et al., 1999; Ward et al., 2005). In this study Cu was spiked as treated wood leachate produced on leaching with DI water. Several dilutions were prepared by mixing treated wood leachate with the surface water samples collected and also with MHW. Then these samples were assayed following the MetPLATE protocol, as previously described. Step by step procedure for Cu-binding capacity is preseted in Figure A-5.The HMBC for copper was expressed as the ratio of the EC 50 of treated wood leachate in surface water sample to the EC 50 of the same leachate in MHW, as expressed in the following equation: WaterHard ModeratelyECSample Water SiteECHMBC5050 (1)

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138 Treated Wood DI LeachateTreated Wood DI Leachate Surface Water Surface Water Moderately Hard WaterModerately Hard Water MetPLATEMetPLATEToxicity Analysis Toxicity Analysis in triplicate on several dilutionsin triplicate on several dilutions Shaking at 160 RPM for Shaking at 160 RPM for 60 minutes60 minutes Shaking at 160 RPM for Shaking at 160 RPM for 60 minutes60 minutes WaterHard ModeratelyECSample Water SiteECHMBC5050 Treated Wood DI LeachateTreated Wood DI Leachate Surface Water Surface Water Moderately Hard WaterModerately Hard Water MetPLATEMetPLATEToxicity Analysis Toxicity Analysis in triplicate on several dilutionsin triplicate on several dilutions Shaking at 160 RPM for Shaking at 160 RPM for 60 minutes60 minutes Shaking at 160 RPM for Shaking at 160 RPM for 60 minutes60 minutes WaterHard ModeratelyECSample Water SiteECHMBC5050 Figure A-5 Step by step procedure for cu binding capacity measurement in different surface waters

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139 A.3 Arsenic and Chromium Concentrations in CCA-Treated Wood Leachates Leaching Solutions DIMHWKRSJRLOLALWWL-1WL-2AOLL Arsenic (mg/L) 0.00.20.40.60.81.01.21.41.6 Leaching Solutions DIMHWKRSJRLOLALWWL-1WL-2AOLL Chromium (mg/L) 0.000.050.100.150.200.250.300.35 Figure A-6 Arsenic and Chromium concentration in CCA leachates from different surface waters (The error bars represent the standard deviation of four replicates)

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140 A.4 Boron Concentration in the ACQand CBA-Treated Wood Leachates DIMHWKRSJRLOLALWWL-1WL-2AOLL Boron (mg/L) 024681012 ACQ CBA DIMHWKRSJRLOLALWWL-1WL-2AOLL Boron (mg/L) 02468101214 Figure A-7 Boron concentration in ACQ and CBA leachates from different surface waters (The error bars represent the standard deviation of four replicates)

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141 A.5 Labile Copper as a Function of Alkalinity and Total Organic Carbon Alkalinity (mg/L) in Leaching Solutions 02040608010012 0 Labile Cu (mg/L) 0100200300400500600700 CCA ACQ CBA TOC (mg/L) in Leaching Solutions 050100150200 Labile Cu (mg/L) 0100200300500600700 CCA ACQ CBA Figure A-8 Labile Copper as a function of alkalinity and TOC of leaching solutions

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APPENDIX B ADDITIONAL MATERIAL FOR RELATIVE RISK FROM VARIOUS TREATED WOOD PRODUCTS B.1 Construction of Decks Pressure treated wood lumber (CCA, ACQ and CBA) was purchased from Central Builders Supply in Gainesville, Florida. The Envirosafe TM treated wood was purchased from a wood treatment company (Cook Lumber) in Tampa, Florida. Two different sizes of lumber 2" 4" and 4" 4" were used for deck construction. The plan view of the built deck is shown in Figure B-1. The deck is 4' 4' in plan view. The sectional view of the deck is as presented in Figure B-2. The lumber was cut to the required sizes. The number of fresh cut faces of lumbers were tried to be kept the same for each deck. The different members of the deck were put together using stainless steel screws. Screws were drilled in to the wood using a power drill. Figure B-3 presents the as-built deck. The tub in which decks are placed is 52"" in area with a depth of 33-inches. They are shown in Figure B-4. 142

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143 Figure B-1 Plan view of a deck (Dimensions in inches) Figure B-2 Sectional view of a deck (Dimensions in inches)

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144 Figure B-3 As built decks Figure B-4 Tubs in which decks were placed

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145 B.2 Organic Analysis Method for organic analysis used was the same as the one used by Stook (2001). DDAC and Tebuconazole concentrations in the deck runoff and the soil column eluents were determined as per the method outlined below. B.2.1 Method for Determining DDAC Concentrations in ACQ This method was adapted from a procedure developed by Chemical Specialties, Incorporated, Charlotte, NC. The method is a two-phase titration using the leaching fluid as one phase and chloroform as the second phase along with an indicator dye (methylene blue). The method is based on DDAC being a cationic surfactant, and sodium dodecyl sulfate is an anionic surfactant. An aqueous sample containing DDAC and methylene blue is placed into a container with chloroform. Two distinct phases are seen. There is a blue aqueous layer containing the DDAC and a clear chloroform layer. The sample is then titrated with sodium dodecyl sulfate (SDS). SDS forms a more stable complex with DDAC and the indicator dye is displaced into the chloroform layer, which turned blue (AWPA, 1999). The analysis of the DDAC component of ACQ began with the preparation of solutions. The first solution was 0.002 M SDS, which was prepared by oven weighing several grams at 105 o C to a constant weight. Once dried, 0.575 g (to the nearest 0.0001 g) of the material was weighed and placed into a 250 ml beaker. This was then diluted with approximately 100 ml of DI water. The mixture was then transferred to a one-liter volumetric flask and diluted to volume with DI water. The 0.002 M Hyamine 1622 solution was prepared by weighing 0.90 g (to the nearest 0.0001 g) of the material, which had been dried at 105 o C to a constant weight. The weighed sample was placed into a one liter volumetric flask and brought up to volume with DI water. The final solution

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146 preparation consisted of placing 0.03 g of methylene blue and 50 g of sodium sulfate into a 1-L volumetric flask and diluting to volume with 0.43 N sulfuric acid. Once the solutions were made, the SDS solution was standardized against the Hyamine 1622 solution. First, 20 ml DI water, 10 ml chloroform and 2 ml of the methylene blue solution were placed in a 100 ml glass jar. A 5 ml aliquot of the 0.002 N Hyamine 1622 solutions was placed in the jar and shaken vigorously. The jar was then opened to allow for the release of gas. The solution is then slowly titrated with 0.002 M SDS. The jar is capped, shaken, and opened after each addition of SDS. The end point of the titration is reached when the chloroform layer (bottom) changed from a colorless liquid to light blue. The molarity of the solutions was determined by the following equations: L1.0448.1(g) mass 1622 HyamineM1 (1) SDS of ml titrationin used 1622 Hyamineof mlM1M2 (2) The actual sample titration procedure began by placing 10 ml of chloroform, and 2 ml of methylene blue into a glass jar by graduated cylinder. An aliquot of 25.0 g (to the nearest 0.001 g) of sample solution is then added to the jar and the mass was recorded. The jar was then capped, shaken well and opened to reduce the build up of gas. The organic layer at the bottom of the jar was colorless at the beginning of the titration. The SDS solution was then titrated slowly into the sample mixture until the end point (the organic layer turns light blue). The end point was exceeded if the aqueous layer turned white and the chloroform layer turned blue. The DDAC concentration in the solution was determined by the following calculation:

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147 (g) sample of mass1000100g/mole 362M2%DDAC (3) B.2.2 Method for the Determination of Tebuconazole This method is an AWPA (2000) Standard method to determine the concentration of tebuconazole in treated wood leachates. The method as published is for the extraction and analysis using gas chromatography Nitrogen Phosphorous Detector (GC-NPD), but the samples were analyzed using gas chromatography coupled with Flame Ionization Detector (GC-FID). The leachate samples were saturated with sodium chloride, extracted with methylene chloride and concentrated prior to analysis on the GC-FID. Appropriate spikes and blanks were included in all analysis. All glassware were washed and then rinsed with methanol followed by a rinse with acetone. The glassware were allowed to air dry prior to use in analysis. A 500-ml aliquot of leachate was placed in a 1-liter separatory funnel. The samples were then saturated with 100 g of American Chemical Society (ACS)-grade sodium chloride (NaCl). The separatory funnels were then capped and shaken to dissolve the NaCl. The caps were removed and 30 ml of methylene chloride was added to each funnel. The caps were replaced and the separatory funnels were vigorously shaken for 3 minutes. The samples were allowed to rest for 10 minutes to allow the aqueous phase and the organic phase to separate. After 10 minutes, the caps were removed and the organic phase is drained into 250 ml beakers. This procedure was repeated two additional times. Once the extraction was complete, the samples were filtered through ACS grade sodium sulfate to remove any residual water and placed into Turbo-vap tubes. The

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148 Turbo-vap was turned on prior to use and allowed to heat to 40 o C with nitrogen pressure between 8 to 15 psi. The samples are then reduced to 1 ml, during the process of volume concentration; the sides of the tubes were rinsed three times with methylene chloride to remove any residual organics that may have adsorbed to the sides of the container. The samples were then allowed to reduce to just less than 1 ml. The samples were removed from the turbo-vap and brought up to 1 ml with methylene chloride. A 500-ul aliquot of the sample was placed in an autosampler vial for analysis. Appropriate spikes and blanks were included in the analysis. B.2.3 Calculation of Soil Cleanup Target Level for DDAC and Tebuconazole The available toxicological data has been reviewed for both DDAC and tebuconazole and has been summarized in Table B-1 of Appendix B. Table B-1 Summary of toxicological data a for DDAC and tebuconazole Chemical Toxicity Test Type Species Used Reported NOEL b (mg/kg-day) Chronic Dog 10.0 Oncogenicity Mouse > 1000 Reproduction Rat 750 Teratology Rat 50 DDAC Teratology Rabbit 10 Chronic Dog 2.96 Oncogenicity Mouse 180 Reproduction Rat 27.1 Teratology Rat 60.0 Tebuconazole Teratology Rabbit 10 a Source: California EPA, 2003; b NOEL: No observed effect level Model equation for developing the acceptable risk based concentrations in soil is borrowed from Saranko et al., (1999) as presented below. The SCTL was calculated only for ingestion oral route. SCTL = mgkgIRRfDFCEDEFATBWTHIoo/1016 (B1)

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149 SCTL = Soil Cleanup Target Level THI = target hazard index (unitless) BW = body weight AT = averaging time (days) EF = exposure frequency (days/year) ED = exposure duration (years) FC = fraction from contaminated source (unitless) IR o = ingestion rate, oral (mg/day) RfD o = Reference dose (oral) mg/kg-day. RfD 0 was calculated using the chronic toxicity NOEL data available with dog of 10 mg/Kg-day, with an uncertainty factor of 100. RfD 0 = daykgmgdaykgmg/ 1.0100/10 Data used for calculation: THI = 1.0, BW = 15kg, AT = 6 years = 2190 days, EF = 365 days/yr; ED = 6 years; FC = 1.0; IR o = 200mg/day; Putting in these values in the equation B1, the SCTL value for DDAC is calculated as: 21.4mg/kg. For Tebuconazole, RfD o values was calculated using the same approach as for DDAC, with NOEL data on dog of 2.96 mg/kg-day. The SCTL value was obtained as 6.4mg/kg. B.2.4 Calculation of Groundwater Cleanup Target Level for DDAC and Tebuconazole Equation for deriving site-specific cleanup target levels for non-carcinogens in groundwater has been borrowed from Saranko et al., (1999) as presented below. consp.oralWCFRSCBWRfDg/L)( GWCTL (B2) Where: RfD oral is the same value calculated in section B.2.3, with values for DDAC and tebuconazole as 0.1 mg/kg-day and 0.0296 mg/kg-day respectively. For other parameters default values from Florida Department of Environmental Protection’s “Groundwater Guidance Concentration Manual” was used (FDEP, 1994). BW = 70 kg, RSC=20%, CF = 1000, and W consp = 2

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150 Plugging in these numbers in equation B2, the GWCTL was calculated as: DDAC = 700g/L; Tebuconazole = 207g/L. B.2.5 Soil Cleanup Target Level (SCTL) and GWCTL Values for Preservative Components Table B-2 SCTL and GWCTL values for preservative components Element Residential (mg/kg) Industrial (mg/kg) GWCTL (mg/L) Copper 12.0 150 89,000 1.0 Boron 17,000 430,000 0.63 Arsenic 2.1 12.0 0.05 (0.01)b Chromium 210 470 0.1 DDACa 2.14 0.7 Tebuconazolea 6.4 0.21 a Calculated as per detail presented in above two sections, b Effective Jan 1, 2006 Cumulative Deck Runoff (Litres) 050100150200250 Cumulative Cu (mg) 0200400600800 CCA ACQ CBA

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151 Figure B-5 Cumulative copper concentrations in deck runoffs Cumulative Deck Runoff (Litres) 050100150200250 Cumulative B (mg) 05001000150020002500 ACQ CBA DOT Figure B-6 Cumulative boron concentrations in deck runoffs Cumulative Deck Runoff (litres) 050100150200250 Cumulative As and Cr (mg) 050100150200250 As Cr

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152 Figure B-7 Cumulative arsenic and chromium concentrations in deck runoffs Cumulative Deck Runoff (litres) 050100150200250 Cumulative Concentration (mg) 0246810121416182022 DDAC Tebuconazole Figure B-8 Cumulative DDAC and tebuconazole concentrations in deck runoffs

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153 Eluent Volume (mL) 0100020003000400050006000 Cumulative Cu (g) 02004006008001000 CCA-Cu ACQ-Cu CBA-Cu Sandy Horizon Eluent Volume (mL) 0100020003000400050006000 Cumulative Cu (g) 02004006008001000 CCA-Cu ACQ-Cu CBA-Cu Organic Horizon Clay HorizonEluent Volume (mL) 0100020003000400050006000 Cumulative Cu (g) 0100200300400500 CCA-Cu ACQ-Cu CBA-Cu Figure B-9 Cumulative copper concentrations in soil column eluents

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154 Sandy HorizonEluent Volume (mL) 0100020003000400050006000 Cumulative Boron (g) 050010001500200025003000 ACQ-B CBA-B DOT-B Organic HorizonEluent Volume (mL) 0100020003000400050006000 Cumulative Boron (g) 02004006008001000120014001600 ACQB CBA-B DOT-B Clay HorizonEluent Volume (mL) 0100020003000400050006000 Cumulative Boron (g) 0100200300400500 ACQ-B CBA-B DOT-B Figure B-10 Cumulative boron concentrations in soil column eluents

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155 Eluent Volume (mL) 0100020003000400050006000 Cumulative As and Cr (g) 050100150200250300 As-Sandy Cr-Sandy As-Org Cr-Org As-Clay Cr-Clay Figure B-11 Cumulative arsenic and chromium concentrations in soil column eluents

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APPENDIX C ADDITIONAL MATERIAL FOR TREATED WOOD LEACHING IN MSW LEACHATE C.1 Impact of pH on Copper Leaching from ACQ and CBA Treated Wood Sawdust Samples ACQ and CBA sawdust samples were leached over a pH range of 4 through 8 using DI water and 0.1N HNO 3 or 0.1N NaOH to adjust the pH of the leaching solution. 10gm of sawdust samples was mixed with 100mL of DI water and mixed at 32 RPM for 2 hours. At the end of 2 hours, pH of the samples were recorded and adjusted to the desired pH by either using HNO 3 or NaOH solution. The sample was mixed again at 32 RPM for 1 hour, the pH adjustment step was repeated few more times until the change in pH after rotation was less than 5%. The set of samples were extracted for 18 hours starting at this hour (after pH adjustment and stabilization). At the end of 18 hours, pH was recorded; sample was filtered and analyzed for Cu as any other leachate sample as mentioned in detail in the method section of this chapter. The variation of Cu concentration over pH is presented in Figure C-1 and C-2 for ACQ and CBA-treated wood samples. 156

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157 ACQpH 345678 9 Copper (mg/L) 2628303234363840424446 Figure C-1 pH impact on Cu leaching from ACQ-treated wood sawdust samples CBApH 456789 Cu(mg/L) 80859095100105110115120 Figure C-2 pH impact on Cu leaching from CBA-treated wood sawdust sample

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158 C.1 Copper Leaching as a Function of Various Leachate Parameters Ammonia (mg/L) 0200400600800 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) CCAR2=0.83 Ammonia (mg/L) 0200400600800 Cu (mg/L) 1020304050 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) ACQR2=0.43

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159 CBAAmmonia (mg/L) 0200400600800 Cu (mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) R2=0.64 Figure C-3 Copper leaching from treated wood as a function of leachate ammonia

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160 Alkalinity (mg/L as CaCO3) 0100020003000400050006000 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)CCAR2=0.78 Alkalinity (mg/L as CaCO3) 0100020003000400050006000 Cu (mg/L) 1020304050 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2= 0.50ACQ

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161 CBAAlkalinity (mg/L as CaCO3) 0100020003000400050006000 Cu (mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2=0.52 Figure C-4 Copper leaching from treated wood as a function of leachate alkalinity

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162 CCAInitial pH of the Leaching Solution (Leachates) 5.56.06.57.07.58.08.5 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) ACQInitial pH of Leaching Solution (Leachates) 5.56.06.57.07.58.08.5 Cu (mg/L) 1020304050 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)

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163 CBAInitial pH of the Leaching Solutions (Leachates) 5.56.06.57.07.58.08.5 Cu(mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) Figure C-5 Copper leaching from treated wood as a function of initial leachate pH

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164 CCAConductivity (ms/cm) 02468101214 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2=0.87 ACQConductivity (ms/cm) 02468101214 Cu (mg/L) 102030405060 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2=0.48

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165 CBAConductivity (ms/cm) 02468101214 Cu (mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) R2=0.64 Figure C-6 Copper leaching from treated wood as a function of leachate conductivity

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166 CCAORP (mV) -800-600-400-2000 Cu (mg/L) 02468101214 (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(21)(22)(23)(25)(26) ACQORP (mV) -800-600-400-2000 Cu (mg/L) 1020304050 (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(21)(22)(23)(25)(26)

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167 CBAORP (mV) -800-600-400-2000 Cu (mg/L) 304050607080 (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(21)(22)(23)(25)(26) Figure C-7 Copper leaching from treated wood as a function of leachate ORP

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168 CCATDS (mg/L) 02000400060008000 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2=0.71 ACQTDS (mg/L) 02000400060008000 Cu(mg/L) 102030405060 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26) R2=0.27

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169 CBATDS (mg/L) 02000400060008000 Cu (mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(20)(21)(22)(23)(24)(25)(26)R2=0.44 Figure C-8 Copper leaching from treated wood as a function of leachate TDS

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170 CCACOD (mg/L) 02000400060008000 Cu (mg/L) 02468101214 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(21)(22)(23)(24)(25)(26)R2=0.37 ACQCOD (mg/L) 02000400060008000 Cu (mg/L) 102030405060 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(21)(22)(23)(24)(25)(26)

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171 CBACOD (mg/L) 02000400060008000 Cu(mg/L) 304050607080 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(19)(21)(22)(23)(24)(25)(26)R2=0.21 Figure C-9 Copper leaching from treated wood as a function of leachate COD

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APPENDIX D ADDITIONAL SIMULATED CONSTRUCTION AND DEMOLITION DEBRIS LANDFILL STUDY DATA D.1 Lysimeter Construction and Installation NOTES 1. 0.6 m (24”) PIPE HDPE SDR 32.52. 7.5cm (3”) RISER PIPE EXTRUSI0N WELDEDTO OUTSIDE OF MAIN 0.6m (24”) PIPE 5m (16.5 ft)7.5cm (3”) HDPE0.6 m (24”) DIA HDPEREMOVABLE CAPS :PLUG OR THREADED NOTES 1. 0.6 m (24”) PIPE HDPE SDR 32.52. 7.5cm (3”) RISER PIPE EXTRUSI0N WELDEDTO OUTSIDE OF MAIN 0.6m (24”) PIPE 5m (16.5 ft)7.5cm (3”) HDPE0.6 m (24”) DIA HDPEREMOVABLE CAPS :PLUG OR THREADED Figure D-1 Schematic of lysimeter 172

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173 Geonetconnecting two pipes Geonetconnecting two pipes Figure D-2 Lysimeter construction photographs Figure D-3 Lysimeter placement inside the landfill (Photo Credit: Dr. Tim Townsend)

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174 D.2 Experimental Site Detail As presented in Figure D-3, the lysimeter were buried in a municipal solid waste landfill next to an approach road. By putting the Lysimeters in the landfill surrounded by municipal solid waste help moderate the temperature of the waste in the lysimeter. As mentioned in the chapter-5, the temperature of the waste in the lysimeter ranged from 35 0 C (at top) to 50 0 C (towards bottom of the lysimeter). The landfill site is Polk County North Central Landfill located in central Florida. The landfill opened in 1976 and today it accepts the majority of waste from the country’s 500,000 residents. D.3 Lysimeter Loading and Compaction LBPLBP CCACCA ACQACQ LBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQ River Rock LBP, ACQ LBP, ACQ Hg lamps LBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQ River Rock LBP, ACQ LBP, ACQ Hg lamps LBPLBP CCACCA ACQACQ LBPLBP CCACCA ACQACQ LBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQ River Rock LBP, ACQ LBP, ACQ Hg lamps LBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQLBP, ACQ River Rock LBP, ACQ LBP, ACQ Hg lamps Figure D-4 Lysimeter loading and compaction of waste components

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175 D.4 Predicted Cu Concentration in Batch Leaching Tests The sulfide concentration in the control leachate used for leaching test was 330mg/L (1.03 10 -3 moles/liter). The solubility product (K sp ) of CuS (@ room temp of 25C and standard conditions) is equal to 10 -35.96 . Copper concentration needed to exceed the K sp value is calculated as below: Lmg/10 6.35 moles/L10 10 1.0310 SK Cu29-32.96-3--35.96-2sp2 (D1) Therefore Cu concentration would be expected to be below detect in the batch leaching

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LIST OF REFERENCES Adler-Ivanbrook, L. and Breslin, V., (1998). Accumulation of copper, chromium and arsenic in blue mussels (Mytilus Edulis) from laboratory and field exposures to wood treated with chromated copper arsenate type C, Environmental Toxicology and Chemistry, 18(2), 213-221. Adriano, D., (2001). Trace elements in terrestrial environments biogeochemistry, bioavailability, and risk of metals, 2 nd Edition, Springer-Verlag, New York. APHA, AWWA, WEF, (1995). Standard methods for the examination of water and wastewater, 19 th Edition. AWPA, (1996). American wood preservers’ association book of standards, American wood-preservers’ association, Granbury, TX. AWPA, (1999). E11-97 Standard method of determining the leachability of wood preservative, American wood preservers’ association book of standards, American wood-preservers’ association, Granbury, TX. Arnold, W., (2005). Effects of dissolved organic carbon on copper toxicity: implications for saltwater copper criteria, Integrated Environmental Assessment and Management, 1(1), 34-39. Barlaz, M., Rooker, A., Kjeldsen, P., Gabr, M. and Borden, R., (2002). Critical evaluation of factors required to terminate the post closure monitoring period at solid waste landfills, Environmental Science and Technology, 36(16), 3457. Benjamin, M., (2001). Water Chemistry, McGraw Hill publications, New York, USA. Bitton, G., (2005). Wastewater Microbiology, 3 rd ed. Wiley & Sons, New York. Bitton, G., Jung, K. and Koopman, B., (1994). Evaluation of a microplate assay specific for heavy metal toxicity, Archives of Environmental Contamination and Toxicology, 27, 25-28. Brand, L., Sunda, W. and Guillard, R., (1986). Reduction of marine phytoplankton reproduction rates by copper and cadmium, Journal of Experimental Marine Biology and Ecology, 96, 225-250. 176

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177 Breslin, V. and Adler-Ivanbrook, L., (1996). Release of copper, chromium and arsenic from CCA-C treated lumber in estuaries, Estuarine Coastal and Shelf Science, 46, 111-125. Brown, P. and Markich, S., (2000). Evaluation of the free ion activity model of metal-organism interaction:extension of conceptual model, Aquatic Toxicology, 51(2), 177-194. CCR, 1998. California Code of Regulations, Title 22 Chapter 11, Article 5, Appendix II. CFR, 2003. Code of Federal Regulations, Title 40 Part 261.24. CFR, 2004. Code of Federal Register, 40 CFR 258. Cai, Y., Cabrera, J., Georgiadis, M. and Jayachandran, K., (2002). Assessment of arsenic mobility in the soils of some golf courses in south Florida, Science of the Total Environment, 291, 123. Cernuschi, S., Giugliano, M. and de Paoli, I., (1990). Leaching of residues from MSW incineration, Waste Management and Research, 8, 419-427. Chirenje, T., Ma, L., Clark, C. and Reeves, M., (2003). Cu, Cr and As distribution in soils adjacent to pressure-treated decks, fences and poles. Environmental Pollution, 124, 407. Chow, C., Kolev, S., Davey, D. and Mulcahy, D., (1996). Determination of copper in natural waters by batch and oscillating flow injection stripping potentiometry, Analytica Chimica Acta, 330, 79-87. Clark, C., Jambeck, J. and Townsend, T., (in-press). A review of construction and demolition debris regulations in the U.S., Critical Reviews in Environmental Science and Technology. Cockcroft, R. and Laidlaw, R., (1978). Factors affecting leaching of preservatives in practice, IRG/WP/3113, International Research Group on Wood Protection, Stockholm, Sweden. Cooper, P., (1991). Leaching of CCA from treated wood: pH effects, Forest Products Journal, 41(1), 30-32. Cooper, P., (1994). Leaching of CCA: Is it a problem? In environmental considerations in the manufacture, use and disposal of preservative-treated wood, Forest Products Society, Madison, WI, 45-57. Cooper, P. and Ung, Y., (1993). A simple quantitative measure of CCA fixation, Forest Products Journal, 43(5), 19-20.

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BIOGRAPHICAL SKETCH Brajesh Kumar Dubey was born on September 18, 1974, to Shri Pabindra Kumar Dubey and Smt. Rambha Dubey at Kharagpur, West Bengal, India. He graduated from Indian Institute of Technology (IIT), Kharagpur with a Bachelor of Technology (Hons) in Civil Engineering in June of 1997. He worked as a Civil Engineer at Engineers India Limited, New Delhi from July of 1997 until June of 2001 before enrolling in the PhD program at the Department of Environmental Engineering Sciences, University of Florida. He married his wife, Abhilasha, on April 20, 2001. After graduation, he will be working as a Post-Doctoral Associate with Professor Timothy Townsend at the University of Florida. 186