Handbook of Pollution Prevention and Cleaner Production Vol. 2: Best Practices in the Wood and Paper Industries

William Andrew is an imprint of Elsevier The Boulevard, Langford Lane, Kidlington, Oxford, OX5 1GB, UK 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA First edition 2010 Copyright Ó 2010, Nicholas P. Cheremisinoff and Paul E. Rosenfeld. Published by Elsevier Inc. All rights reserved The rights of Nicholas P. Cheremisinoff and Paul E. Rosenfeld to be identified as the authors of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangement with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. British Library Cataloguing in Publication Data Cheremisinoff, Nicholas P. Best practices in the wood and paper industries. 1. Forest products industrydEnvironmental aspects. 2. Paper industrydEnvironmental aspects. 3. Wood-pulp industrydEnvironmental aspects. 4. Best management practices (Pollution prevention) I. Title II. Rosenfeld, Paul E. 674.8’4-dc22 Library of Congress Control Number: 2009938289 ISBN: 978-0-08-096446-1 For information on all William Andrew publications visit our website at elsevierdirect.com Printed and bound in the United States of America 09 10 11 12 11 10 9 8 7 6 5 4 3 2 1

Acknowledgements

While there are a large number of individuals who have helped to shape and contribute to this volume, we thank them all but wish to acknowledge two individuals in particular. First, we wish to acknowledge Mr Christopher Cagney Waller, B.S. in civil engineering from UCLA class of 2009, who is currently doing an internship at SWAPE under the guidance of Dr Paul Rosenfeld. Mr Waller was instrumental in editing the manuscript, in conducting research for information used in certain sections, and in preparing draft notes for the authors. The second individual we wish to acknowledge is Mr Dennis Davis of Somerville, Texas. Mr Davis worked at a wood-treating facility for more than 30 years. He provided his time and insight into the handling and operational practices of wood-treating plants. His intimate knowledge of specific practices helped to clarify a number of issues concerning the evolution of fugitive emissions at these types of facilities. Mr Davis was also a great inspiration on a personal level. He has been diagnosed with an incurable cancer associated with his many years of working in the industry sector. Throughout his illness he has shown great resolve, fortitude, and an unwavering sense for living every day to the fullest. The authors wish to thank Elsevier for their continued interest in working with us and for their efforts in the fine production of this volume.

About the authors

Nicholas P. Cheremisinoff is a chemical engineer specializing in the safe handling and management of chemicals and hazardous materials with more than 35 years of industry and applied research experience. He earned his B.Sc., M.Sc., and Ph.D. degrees in chemical engineering from Clarkson College of Technology. He is a consultant to industry and foreign governments, private sector corporations, international lending institutions such as the World Bank Organization, the US Export–Import Bank, donor agencies including the US Agency for International Development and the US Trade and Development Agency, the European Union, the US Department of Energy and the US Department of Defense, and has served as a technical consultant and advisor on industrial waste, worker safety, environmental management, and process safety. Additionally, he has served as consultant and advisor to various foreign ministries on policymaking issues concerning environmental management and responsible industry practices, including the governments of Jordan, Ukraine, the Russian Federation, and Nigeria. He is the author, co-author, or editor of 160 technical reference books. Paul E. Rosenfeld is an environmental chemist with over 20 years of experience. His focus is fate and transport of environmental contaminants, risk assessment, and ecological restoration. His project experience ranges from monitoring and modeling of pollution sources as they relate to human and ecological health. Dr Rosenfeld has investigated and designed cleanup programs and risk assessments for contaminated sites containing pesticides, radioactive waste, PCBs, PAHs, dioxins, furans, volatile organics, semi-volatile organics, chlorinated solvents, perchlorate, heavy metals, asbestos, odorants, petroleum, PFOA, unusual polymers, and fuel oxygenates. He received a B.A. in Environmental Studies from UC Santa Barbara, an M.S. in Environmental Science, Policy and Management from UC Berkeley, and a Ph.D. from the University of Washington.

Preface

This is the second volume in a series on cleaner production and pollution prevention. The intent of the series is to provide guidance on best management practices, technologies, and approaches to managing environmental aspects. The world is currently in the midst of the worst financial recession in more than 70 years. While the Chairman of the Federal Reserve announced in August of 2009 that signs of recovery show that the world financial meltdown is ending, the fact remains that unemployment is at an all-time high, with official figures in the league of 10% to unofficial estimates soaring to 20% in the USA. The media has touted the recovery as a jobless recovery – which simply means that unemployment is likely to remain high for some time, and productivity low. Looking back to the era of the last Great Depression, it took a world war and subsequent reconstruction to return industrial levels of production to normality. But in both the war years and postwar years of growth, prosperity and technological innovations, industrial activities ran with little oversight. Industrial activities consumed natural resources at paces we now acknowledge as both unsustainable and environmentally damaging. While strict environmental regulations introduced throughout the decades stretching from the early 1970s through to the mid-1990s curtailed the environmental footprint created by industry, both the new and likely next generation are still faced with an aftermath of damages to groundwater, soil, the air we breathe, and global climate change that need to be addressed. And if we misplace priorities and decide that the only way to return to prosperity is by placing environmental protection at a low priority, as was clearly national policy under the last administration in the USA, then we will simply continue down a path of destruction that has global consequences. It is both unrealistic and irresponsible to separate environmental management from infrastructure investments and business strategies and policies. Companies that make it a policy and overall strategy to only meet their minimum statutory requirements are in fact not managing both the financial and environmental aspects of their businesses responsibly. This narrow-minded approach to environmental stewardship simply is a license to pollute, because if a particular standard or regulation has not been enacted, then industry can do as it pleases with the wastes generated from manufacturing. As an example, the American Wood Preservers’ Association and the Association of American Railroads have argued for decades that there are no definitive studies that link carcinogenicity with the hundreds of chemicals that make up coal tar creosote, and with

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pentachlorophenol, and arsenical chemicals used in the preservation of wood. To argue differently would severely restrict the use of and even result in delisting of these chemicals since they are all registered pesticides. Despite industry, academic, medical, and governmental studies including and predating those of the National Institute of Occupational Safety and Health (NIOSH), the American Conference of Governmental Industrial Hygienists (ACGIH), the International Agency for Research on Cancer (IARC) and the Occupational Safety and Health Administration (OSHA), the wood-preserving industry continued to take a stand that as long as these chemicals are used within industry guidelines, the risks to communities, the consumer, and the environment are minimal. In short, industry knows best and will ensure that workers and neighboring communities will not be affected by exposures to such chemicals. Prior to 1992 wood-treating companies could allow these chemicals to drip and spill on to bare ground. There are wood-treating facilities in the USA that have been operating for 100 years and have eight or more decades of cumulative spills to property. In 1992 the US Environmental Protection Agency (EPA) finally got around to saying enough is enough. This practice contaminates the groundwater and creates airborne emissions that may enter into communities. So the EPA passed a standard requiring drip pads to be installed to collect the spills and drips that the industry had allowed for nearly a century. The industry understood that the chemicals it uses are toxic, linked to cancers, and can contaminate groundwater and storm water. It is no leap in logic that when contaminated groundwater and storm water travel off the plant property it carries these same chemicals for people to come into contact with from well water or when walking through puddles or swimming in lakes or fishing in streams. But because there were no statutory standards, the industry could ignore these pathways to toxic exposures. Prior to the 1990s, with the introduction of boiler industrial furnace (BIF) standards, many wood-treating facilities could burn toxic sludge and treat wood in wood-waste boilers legally. A number of facilities grandfathered 30-year-old boilers with minimal to no air pollution controls prior to these standards, burning their wastes in an uncontrolled manner, and introducing millions of pounds of polycyclic aromatic hydrocarbons (PAHs) and dioxins into the atmosphere, exposing neighboring communities. The science, technologies, and tools were there 40 years ago for stack testing, monitoring, and controlling stack emissions – but these cost money, and if there are no regulations or required standards, why should a company reduce its profits by installing and operating such equipment? This kind of sounds like a child – if you tell your 8-year-old to do what he or she thinks is best, even with warnings against consequences, what do you think they will do? On the whole, the wood-preserving industry has historically operated its facilities like toxic waste dumps. It buried, spilled, burned, stockpiled, and lagooned hundreds of millions of tons of toxic waste on properties that bordered residential communities. Since 1980, the EPA has classified 56 wood-preserving sites as Superfund sites. At about 40 of these sites, the EPA has completed the

Preface

xiii

process of selecting a cleanup strategy for the soil, sludge, sediments, and water contaminated by wood treatment wastes. If we conservatively assume that remediation costs are $20 million per site, then the cost to American taxpayers can exceed $1.1 billion. Add to this the costs for medical monitoring for communities that have been exposed to air pollution or whose groundwater has been contaminated, or continue to receive toxic emissions from contaminated soils that become airborne, or are subjected to the pollution from wood-waste boilers, as well as healthcare costs from workers and community members who are battling illnesses from chemical exposures, then the costs to society are staggering. New Jersey and New York are states that have banned the manufacture and use of creosote-treated wood. We believe this is a prelude to the demise of the industry and has long been overdue. The industry on the whole has misrepresented the dangerous nature of the chemicals it uses, has failed to act responsibly in reporting its emissions accurately, has not been transparent in quantifying its emission sources, and has misrepresented that the benefits these products bring to society outweigh the negative impacts. Many will argue that modern wood-treating plants are not environmentally damaging because there are better technologies, industry understands more, and there are stringent regulations and environmental enforcement today. But we think old habits are hard to break. While the gross housekeeping and uncontrolled waste burying and burning has been eliminated, wood-treating facilities simply do not report accurate and transparent air emissions. The same problem exists within the pulp and paper industry. The standard approach in the USA to reporting air pollution emissions is by means of calculation and not measurement. To the company, the US EPA’s AP-42 is relied upon for the application of emission factors to calculate yearly emissions and report these under the Toxics Release Inventory program, which is a legal requirement. The objective of TRI is to inform the public of pollution in their communities and to provide a basis to monitor industry activity. But emission factors are based on measurements reported by industry itself more than 30 years ago. AP-42 emission factors are not plant specific, they are not necessarily representative of all plants, they are not based on statistical sampling for a large number of facilities, they do not reflect the age and inefficiencies of older operating equipment, and they do not consider upsets and transient operating conditions that occur on a regular basis at operating plants. In examining AP-42 emission factors for the wood-treating industry, we find that emission factors for a mere eight PAHs out of a possible 130 chemicals found in this product are reported, and further all of the factors provided by industry are referenced to ambient conditions and not actual handling conditions. The same publication offers no reasonable guidelines to account for the effect of surface area with exposures from treated wood, which has a direct impact on the magnitude and duration of fugitive emissions from the surfaces of treated wood. The pulp and paper industry has similar if not identical shortcomings in its reporting of emissions. It bases emissions reporting on self-reported emissions using emission factors that were measured in the 1960s and 1970s. Stack testing

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and independent emissions monitoring are performed under steady-state conditions, with upsets rarely reported or required to be reported. Such practices are unreasonable, especially based on the human health risk tools and precision of monitoring instrumentation we have available today. Furthermore, we believe that many companies simply have ignored the financial benefits associated with good environmental performance. Good environmental performance is not simply about meeting statutory requirements. It’s about staying ahead of the game. At the end of the day, business is in business to make business. The basis for our capitalist society is to make profits. When companies are short-sighted and only meet the minimum requirements of statutes, they expose the corporation, shareholders, and employees to financial liabilities from cleanup damages, future enforcement actions, and communities that seek retribution from the negative impacts of the manufacturing operations. The intent of this volume, as with others, is to focus on best management practices and technologies that may help to continually improve environmental performance. A commitment to continual environmental performance is increasingly becoming the standard of care for smart industry leaders. The term ‘‘best practices’’ does not necessarily mean the most costly. A decade ago, best practices simply meant good housekeeping. Practices such as source reduction, chemical substitution, leak detection and repair programs, measurement and monitoring, adaptation of environmental management information systems, and a whole gambit of other low-cost tools and practices can assist facilities to better manage their environmental aspects. This volume contains seven chapters. The first five chapters focus on the wood-preserving industry; however, Chapter 5 has information and discussions that are relevant to both the wood-treating and pulp and paper industry sectors. Chapter 1 provides an overview of the properties and applications of chemicals used in wood treating. Chapter 2 provides a working overview of wood-treating technology with focus on tie and utility pole treatment. Chapter 3 discusses pollution sources and methods of controlling air emissions. Chapter 4 focuses on calculation methods for air emissions from wood-treating plants. Discussions of wood-waste combustion are included in this chapter. Chapter 5 deals with pollution prevention practices in the wood-treating sector, along with discussions on conducting an initial environmental review, the application of environmental management information systems, and the structure and benefits of an environmental management system. Chapter 6 addresses the technologies, sources of pollution, and chemicals of concern and pollution control technologies within the pulp and paper sector. Chapter 7 covers pollution prevention and best practices for the sector. In this last chapter a spotlight on black liquor gasification as an emerging technology is given. Nicholas P. Cheremisinoff Ph.D. Paul E. Rosenfeld Ph.D.

1 Wood-preserving chemicals 1.1 Introduction This chapter describes the chemicals that are used in the preservation of wood. The chapter is followed by a discussion of pressure-treated wood manufacturing technologies. An understanding of both the toxic nature of chemicals used and manufacturing steps is critical to identifying and responsibly managing the many forms of pollution and waste generated in the production of treated wood products. As described in later chapters, a wood-treating plant generates both fugitive and point sources of pollution. While many of these are better managed today, historically the industry has been among the worst polluters, leaving toxic legacies that are likely to be a concern for present and future generations. The industry overall has lagged in adopting good housekeeping and source reduction practices that have been available for more than 70 years. Much of this can be attributed to an industry structure that is historically based on small fragmented business units and enterprises. The USA almost stands as an island unto itself with the industry’s continued dependence on creosote coal tars, pentachlorophenol, and arsenicals. While these chemicals unquestionably provide superior product performance as pesticides designed to kill, they bring with them negative impacts to workers, neighboring communities, and the environment. For more than 30 years the National Institute of Occupational Safety and Health (NIOSH, 1977a) and the Occupational Safety and Health Administration (OSHA, 1978) have labeled creosote as a dangerous chemical that is linked to cancer. The US Environmental Protection Agency (EPA, 1984) has defined creosote, pentachlorophenol, and arsenical treating formulations as chemicals that are potential carcinogens. Austria, India, Indonesia, New Zealand, Sweden, Switzerland, the EU/EEA member states, and Belize are among the international community that have banned, or placed severe restrictions on, the use of pentachlorophenol because of its link to carcinogenicity and the fact that the product contains dioxins. Both New York and New Jersey have banned all use of creosote in treated wood manufacturing as of 2008. There is overwhelming consensus from the scientific community and governmental organizations that the chemicals used by the US wood-preserving industry are dangerous and cancer causing. Companies that continue to use such chemicals have an obligation to employ the best available technologies and practices that eliminate these materials from entering into the air and into surface water run-off that may enter into receiving bodies or pass through communities, and from contaminating groundwater.

Handbook of Pollution Prevention and Cleaner Production Vol. 2 Copyright Ó 2010 by Elsevier Inc. All rights reserved.

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Handbook of Pollution Prevention and Cleaner Production

1.2 Wood types and products The feedstock material used by the industry sector is wood, of which there are several varieties. Primary types of wood exploited by the industry are Douglas fir, southern pine, oak, and mixed hardwood. The products made to service the rail industry are crossties, switches (switch ties), pilings, poles, crossarms, lumber and timber, and fence posts. A crosstie is also referred to as a railroad tie or a tie. The British call a railroad tie a sleeper. It is one of the cross-braces that support the rails on a railway track. Figure 1.1 shows a stack of crossties as they are typically bundled for shipment to a customer. Rail tracks are used on railways which, together with switches, guide trains without the need for steering. The tracks consist of two parallel steel rails, which are laid upon sleepers (crossties) that are embedded in ballast to form the railroad track. The rail is fastened to the ties with spikes, lag screws, bolts, or clips such as Pandrol clips. Figure 1.2 shows crossties arranged in a track. On average, about 3000 railroad ties are used per mile of track. A rail profile is a hot rolled steel profile of a specific shape or cross-section (an asymmetrical I-beam) designed for use as the primary component of railway track. Railway rails are subject to very high stresses and have to be constructed of very-high-quality steel. Minor flaws in the steel that pose no problems in reinforcing rods for buildings can, however, lead to broken rails and dangerous derailments when used on railway tracks. The rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by the steelworks at one time, so a railway must select the nearest suitable size. Worn, heavy rail from a mainline is often reclaimed and downgraded for reuse on a branchline, siding or yard.

Figure 1.1 Stack of creosote-treated railroad ties.

Wood-preserving chemicals

3

Figure 1.2 Railroad ties comprising a section of track.

Track ballast forms the trackbed upon which railroad ties are laid. It is packed between, below, and around the ties. It is used to facilitate drainage of water, to distribute the load from the railroad ties, and also to keep down vegetation that might interfere with the track structure. This also serves to hold the track in place as the trains roll by. It is typically made of crushed stone, although ballast has sometimes consisted of other, less suitable materials. The term ‘‘ballast’’ comes from a nautical term for the stones used to stabilize a ship. Good-quality track ballast is made of crushed natural rock with particles between 28 and 50 mm in diameter; a high proportion of particles finer than this will reduce its drainage properties, and a high proportion of larger particles result in the load on the ties being distributed improperly. Angular stones are preferable to naturally rounded ones, as these interlock with each other, inhibiting track movement. Soft materials such as limestone are not particularly suitable, as they tend to degrade under load when wet, causing deterioration of the line; granite, although expensive, is one of the best materials in this regard (Ellis, 2006). Usually, a baseplate (i.e. a tie plate) is used between the rail and wood sleepers, to spread the load of the rail over a larger area of the sleeper. Sometimes spikes are driven through a hole in the baseplate to hold the rail, while at other times the baseplates are spiked or screwed to the sleeper and the rails clipped to the baseplate. Tie plates add to the stability of track, lengthen the life of wood ties, and provide uniform wear on the rail head. Tie plates are available in single- or double-shoulder design (see Figure 1.3). Steel rails can carry heavier loads than any other material. Railroad ties spread the load from the rails over the ground and also serve to hold the rails a fixed distance apart (the gauge). Ties are laid across the ballast at intervals of about two feet (roughly 3000 ties per mile). The rails are then laid atop the ties, perpendicular to them. If the ties

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Handbook of Pollution Prevention and Cleaner Production

Figure 1.3 Examples of tie plates.

are wood, tie plates are then set atop the ties on the rail flange, and then spikes or bolts are driven through the tie plates into the ties to clamp down the rails. Historically, US railroads have used driven rail spikes to hold the rail to the tie, while European railways favor square-headed bolts that are screwed into the wood. For concrete ties, steel clips (e.g. the Pandrol clip) are used to fasten the rails. After this is done, additional ballast is then added to fill the spaces between and around the ties to anchor them in place. The ties serve as anchors and spacers for the rails, while providing a slight amount of give to accommodate weather and settling. The ties are ‘‘floating’’ in the top of the ballast. Failure of a single tie is generally insignificant to the usability and safety of the rails. Rails lie somewhat freely in tie plates and sliding movement of the rail through the plate is possible, leading to creeping rails or misaligned or unevenly spaced ties. To prevent this, anchors are placed transversely under the rail at each side of the tie to prevent slippage of the rail and the tie relative to each other. The tie anchor is usually a spring-loaded clip placed with a hammer blow (driven) or with a special lever (wrench). Wood is a versatile and effective material for use as a crosstie. However, the key properties of wood will vary with class of wood type. In order to allow for the potential use of a broad range of wood types, the wood tie properties need to be considered in terms of the categories of wood. The material properties noted herein are based on a collection of data reported from various sources on the Web and are consistent with those presented in the Manual for Railway Engineering of the American Railway Engineering and Maintenance of Way Association (AREMA, 2007). Table 1.1 provides wood property values using the following parameters: 1. Dimensions are for a standard main line wood crosstie and are based on the AREMA specification that allows a ¼-inch reduction in width and depth. The unit of measure is inches. 2. Volume is defined as the total amount of space occupied by the crosstie and is calculated based on the dimensions shown. The unit of measure is cubic feet. 3. Density is mass per unit volume and is based on reported values derived from the testing of small clear specimens of wood using ASTM procedure D-143 and US Forest Service data. Actual whole tie values may differ. The unit of measure is pounds per cubic foot.

1. Dimensions Length (in) Width (in) Depth (in)

Nominal 102 9 7

2. Volume (ft3)

Oak

Northern mixed hardwoods

Southern mixed hardwoods

Southern yellow pine

Softwood

Douglas fir

102 8.75 6.75

102 8.75 6.75

102 8.75 6.75

102 8.75 6.75

102 8.75 6.75

102 8.75 6.75

3.49

3. Density (pcf) (lb/ft3)

69.4

3.49 65.3

3.49 58.9

3.49 62.1

3.49 53.4

3.49 59.7

4. Weight (lb)

238

227

205

216

196

208

5. Moment of inertia (in4)

224

224

224

224

224

224

66.4

66.4

66.4

66.4

66.4

66.4

6. Section modulus (in3) 7. Modulus of elasticity (MOE)

106

1.22

1.29

0.95

8. Modulus of rupture (MOR) (psi)

72F

9392

8893

6810

670

418

Janka Ball

883

690

558

591

9. Rail seat compression test (psi) 10. Material surface hardness test (lb) 11. Static bending strength (in-kips) 12. Stiffness; load/deflection (in) 13. Single tie lateral push test (lb)

0.165 1950

0.157 1900

1.07

1.60

10,508

7144

9299

523

632

430

594

587

565

371

556

453

698

475

618

0.212 1800

1.49

0.134 1850

0.187 1700

Wood-preserving chemicals

Table 1.1 Typical material and tie strength properties

0.125 1800

5

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Handbook of Pollution Prevention and Cleaner Production

4. Weight is the density multiplied by the volume. The unit of measure is pounds. 5. Moment of inertia (MOI) is a measure of the rectangular shape of the crosstie and is calculated around its neutral axis calculated based on the defined dimensions and a rectangular cross-section. The unit of measure is inches4. 6. Section modulus is a measure of the shape of the crosstie and is calculated by dividing the MOI by the greatest distance of the section from the neutral axis, calculated from dimensions and rectangular cross-section. The unit of measure is inches3. 7. Modulus of elasticity (MOE) is the rate of change of unit stress with respect to unit strain under uniaxial loading within the proportional (or elastic) limits of the material. This parameter is a measure of the stiffness of the crosstie, i.e. the relationship between load (stress) and deflection (strain). Values are average reported ones derived from testing of small clear specimens of wood using ASTM procedure D-143 and US Forest Service data. Actual whole tie values may differ. Unit of measure is pounds per square inch. 8. Modulus of rupture (MOR) is a measure of the maximum load-carrying capacity or strength of the crosstie and is defined as the stress at which the material breaks or ruptures (based on the assumption that the material is elastic until rupture occurs). Reported values are those derived from testing of small clear specimens of wood using ASTM procedure D-143 and US Forest Service data. Actual whole tie values may differ. The unit of measure is pounds per square inch. 9. The rail seat compression test is a measure of the crushing strength or load-carrying capacity of the crosstie at the rail seat (under the tie plate) and is defined as load per unit area at which compression of the wood occurs. The unit of measure is pounds per square inch. 10. The material surface hardness (Janka Ball) test is a measure of the surface hardness of the crosstie and is defined as load necessary to push a two-inch-diameter steel ball 0.25 inches into the tie surface. The unit of measure is pounds. 11. Static bending strength is a measure of the strength of the crosstie and is based on a load/deflection test carried out to failure of the wood material (test similar to C-stiffness load/deflection test). The unit of measure is inch-kips. 12. C-stiffness load/deflection is a measure of the flexibility of the crosstie and is based on a load deflection test in which a load of 10,000 lb is applied to the center of the crosstie, which is supported from below at two points 60 inches apart. The deflection is measured. The unit of measure is inches. 13. The single-tie lateral push test is a measure of the lateral resistance of a single crosstie in ballasted track and is representative of the relative resistance of the track to lateral movement in the ballast. Values are based on field tests taken by the US Department of Transportation and are based on ‘‘minimum’’ value for consolidated track adjusted to account for differences in density (weight) of the different crosstie wood materials. The unit of measure is pounds.

1.3 Chemicals used in preservation 1.3.1

Coal-tar creosote

Coal-tar creosote is a brownish black/yellowish dark green oily liquid with a characteristic sharp odor, obtained by the fractional distillation of crude coal tars. The approximate distillation range is 200–400 C as reported in

Wood-preserving chemicals

7

Table 1.2 General properties of creosote Property

Value

Synonyms

Coal-tar creosote, creosote oil, coal-tar oil, creosote P1

CAS nos.

8001-58-9; 90640-80-5 (anthracene oil); 61789-28-4

Molecular mass

Variable (complex mixture of hydrocarbons)

Boiling range

~200–400 C

Density

1.00–1.17 g/cm3 at 25 C

Viscosity

4–14 mm2/s at 40 C

Flash point

Above 66 C

Ignition temperature

500 C

Octanol/water partition coefficient (log Kow)

1.0

Solubility in organic solvents

Miscible with many organic solvents

Solubility in water

Slightly soluble/immiscible

the general public literature. Table 1.2 summarizes the general properties of creosote. The chemical composition of creosotes is influenced by the origin of the coal and also by the nature of the distilling process. This means that creosote components are rarely consistent in their type and concentration. According to the US EPA there are six major classes of compounds in creosote (Willeitner and Dieter, 1984; US EPA, 1987): 

 



 

aromatic hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs (nonheterocyclic PAHs can constitute up to 90% of creosote by weight), and benzene, toluene, ethylbenzene and xylene compounds (known collectively as BTEX); tar acids/phenolics, including phenols, cresols, xylenols, and naphthols (tar acids, 1–3 weight %; phenolics, 2–17 weight %); tar bases/nitrogen-containing heterocycles, including pyridines, quinolines, benzoquinolines, acridines, indolines, and carbazoles (tar bases, 1–3 weight %; nitrogencontaining heterocycles, 4.4–8.2 weight %); aromatic amines, such as aniline, aminonaphthalenes, diphenylamines, aminofluorenes, and aminophenanthrenes, cyano-PAHs, benzacridine, and its methylsubstituted congeners; sulfur-containing heterocycles, including benzothiophenes and their derivatives (1–3 weight %); oxygen-containing heterocycles, including dibenzofurans (5–7.5 weight %).

Table 1.3 provides chemical analyses of several coal-tar creosotes as reported by the US EPA, including the source data that were assembled in the reporting.

8

Table 1.3 Chemical analyses of coal-tar creosotesa Chemical analysis (weight %)b

Aromatic hydrocarbons Indene Biphenyl

Tar acids/phenolics Phenol o-Cresol m-, p-Cresol 2,4-Dimethylphenol Naphthols

(B)

(C)

(D)

(E)

(F)

(G)

0.8*/1.6

2.1

1–4

0.8c

0.6 1.3

0.43 1.45

0.87 4.1

1.3/3.0* 0.9*/1.7 1.2*/2.8 2.0*/2.3

11

13–18 12–17 12.0

7.6 0.9c 2.1c

9.0*/14.7 7.3/10.0* 2.3/3.0* 21* 3.0* 2.0* 4.0* 7.6/10.0* 7.0/8.5* 1.0/2.0*

3.1 3.1

9.0 7–9

8.3c 5.2c

12.32 3.29 7.51 3.42 0.15 12.51 5.03

11.4 8.87 11.5 5.16 0.1 5.86 6.33

12.2

12–16

16.9c 8.2d

10.21 0.45 0.9

6.7 0.54 0.8

1–3.3

2–7

12.9 2.2 4.5 1.6 0.2 5.8 4.6 3.1 11.2 3.1 1.7

2–3 1–5

7.5c 5.3c

4.6 3.7 2.2 0.5 0.22 0.5–1.0 0.2 0.2 0.1

4.41 2.0

2.27 1.13

0.2–2.2 0.1–1.5

0.26

0.17

0.21