Secondary Mill Residues and Urban Wood Waste

Quantities in the United States

Final Report

Prepared for:

Northeast Regional Biomass Program

Washington, D.C.

Prepared by

Jeffrey E. Fehrs, P.E.

Williston, Vermont

December 1999
Secondary Mill Residues and Urban Wood Waste

Quantities in the United States

Final Report

Prepared for:

Northeast Regional Biomass Program

CONEG Policy Research Center, Inc.

400 North Capitol Street, Suite 382

Washington, D.C. 20001

Prepared by

Jeffrey E. Fehrs, P.E.

20 Hideaway Lane

Williston, Vermont 05495

December 1999
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

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TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY.........................................................................................................iii

SECTION I: INTRODUCTION.................................................................................................1

Purpose of this Study ....................................................................................................................1

Types of Wood Residues and Wastes Included in the Study..........................................................2

Definitions....................................................................................................................................2

SECTION II: NATIONAL WOOD WASTE ASSESSMENT SUMMARIES .........................5

Characterization of Building-Related Construction and

Demolition Debris in the United States .........................................................................................7

Characterization of Municipal Solid Waste in the United States: 1997 Update ..............................11

Lignocellulosic Feedstock Resource Assessment ..........................................................................15

Urban Tree Residues: Results of the First National Inventory........................................................19

Urban Wood Waste Resource Assessment ....................................................................................23

Biomass Residue Supply Curves for the United States (Update)....................................................27

The Changing Solid Waste Wood Resource in the United States, 1990-1998 ................................31

SECTION III: ESTIMATES OF NATIONAL WOOD WASTE

 QUANTITIES AND PRICES............................................................................37

Methodology Used to Develop Estimates of Quantities and Prices................................................37

Results..........................................................................................................................................45

APPENDIX A: Bibliography......................................................................................................A-1

APPENDIX B: Matrix Table......................................................................................................B-1

APPENDIX C: Calculated Delivered Residue Cost and Graph of DRC Versus

 Cumulative Percent Available ..........................................................................C-1

APPENDIX D: Calculation of Weighted Average Landfill and Incinerator

 Tipping Fee .......................................................................................................D-1
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Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

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EXECUTIVE SUMMARY

The Northeast Regional Biomass Program (NRBP) has undertaken this study is to assist the U.S.

Department of Energy and other biomass resources and energy stakeholders by providing a clear

understanding on the types and amounts of wood available for fuel (and other uses). This study

focuses on secondary mill residues and urban wood wastes, and estimates quantities and prices

based on seven national wood waste assessments completed by others.

A goal of the study is to build overall confidence in estimates of secondary mill residues and

urban wood waste quantities and prices. This is achieved by obtaining a clear understanding

existing data on wood residues and wastes, identifying residues or wastes for which data is not

available, and analyzing and compiling the data into a defendable estimate of quantities and

prices.

Overall, the results of the analysis indicate that a tremendous amount of secondary mill residues

and urban wood wastes are generated in the U.S., and that a large fraction of that amount is

potentially available for fuel. A summary of wood residue and waste quantities is presented

below.

National Wood Residue and Waste Quantities

WOOD WASTE

TOTOL

GENERATION

(Tons/year)

AVAILABLE

@ up to $10/ton

(Tons/year)

AVAILABLE

@ up to $20/ton

(Tons/year)

AVAILABLE

@ above $20(c)

(Tons/year)

Secondary mill 15,644,000 1,342,000 3,783,000 6,101,000

Construction 16,726,000 2,796,000 7,882,000 12,712,000

Demolition 26,400,000 1,742,000 4,910,000 7,920,000

MSW(a) 11,800,000 1,999,000 5,633,000 9,086,000

Yard trimmings 6,300,000 1,199,000 3,379,000 5,450,000

Urban tree residues 51,455,000 9,962,000 28,074,000 45,280,000

Used pallets(b) 6,544,000 230,000 647,000 1,044,000

Railroad ties 1,688,000 n/a n/a n/a

Land clearing n/a n/a n/a n/a

Used utility poles n/a n/a n/a n/a

TOTAL <136,557,000 <19,270,000 <54,308,000 <87,593,000

(a): Includes used pallets that are disposed in landfills.

(b): Includes used pallets that are repaired, refurbished, or recycled. Used pallets are disposed in landfills are

included as MSW wood waste.

(c): The methodology used to estimate quantities and prices equates wood waste available at $20 and above with

that that potentially available for fuel. Wood waste potentially available as fuel is defined as the quantity

generated less that used by high value markets and that which is commingled, unseparatable, or contaminated.

n/a: Data not available
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Several conclusions can be drawn from the data:

• More secondary mill residues and urban wood wastes are generated and potentially available

that previously estimated.

• Urban tree residues comprise a surprisingly large fraction (about half) of secondary mill

residues and wood wastes potentially available.

• Demolition wood waste comprises the largest fraction of C&D wood waste, but due to

contamination and commingling issues, less demolition wood is potentially available than

construction and renovation wood waste.

• Used railway ties and land clearing wood waste are likely generated in tremendous

quantities, but insufficient information is available to estimate the amounts potentially

available.

• At a delivered price of $0 - $10/ton, woodfuel is considered to be competitive with fossil

fuels, in particular with coal. This analysis indicates that just under 20,000,000 tons/yr are

available at a price of $10/ton.
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SECTION I:

INTRODUCTION

The U.S. Department of Energy, the Regional Biomass Energy Programs, national laboratories,

and others involved in biomass energy require defensible data on biomass resources and costs to

aid in their planning and evaluation of biomass technologies, programs, and policies. The U.S.

DOE and the national laboratories are spearheading research and development of various energy

crops, harvesting and storage technologies, and conversion technologies capable of using

biomass resources for energy. Although several crops appear promising for energy conversion,

currently they are neither grown commercially (except on a limited basis) nor economically

(compared to fossil fuels or biomass residues or wastes used for fuel).

The research and development continues to indicate that energy crops can be grown, harvested,

and processed economically, and that energy crops will be an important source of fuel and

feedstock for biofuels. However, at least in the short term, various low-cost biomass residues

and wastes will continue be used for fuel. Today, most power plants and industrial boilers that

use biomass as a primary or supplemental fuel rely on wood residues and wastes as fuel. At its

peak in early 1990s, thousands of industrial boilers and nearly 50 power plants throughout the

U.S. used wood residues and waste as fuel. The facilities produced about 7,000 MW of power

and an un-estimated amount of thermal and electrical energy for industrial uses.

To date, hundreds, if not thousands of local, state, regional, and national wood residue and waste

resource assessments have been completed. The assessments were completed by a wide variety

of government agencies, private consultants, research or academic entities, and others. The

research methodologies, sources of information, and assumptions used vary depending on the

specific goals, research and analytical technique, as well as budget and time constraints.

When compared to each other, the assessments often present significant variability in the results,

and it is not uncommon for the information or results to appear contradictory. The variability

and contradiction can lead to loss of confidence in the results.

PURPOSE OF THIS STUDY

The Northeast Regional Biomass Program (NRBP) has undertaken this study is to assist the U.S.

Department of Energy and other biomass resources and energy stakeholders by providing a clear

understanding on the types and amounts of wood available for fuel (and other uses). This study

focuses on secondary mill residues and urban wood wastes, and estimates quantities and prices

based on seven national wood waste assessments completed by others.

A goal of the study is to build overall confidence in estimates of secondary mill residues and

urban wood waste quantities and prices. This is achieved by obtaining a clear understanding

existing data on wood residues and wastes, identifying residues or wastes for which data is not
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

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available, and analyzing and compiling the data into a defendable estimate of quantities and

prices.

TYPES OF WOOD RESIDUES AND WASTES INCLUDED IN THE STUDY

The USDA Forest Service performs inventories, collects and analyzes data, and publishes

detailed statistics on both logging and timber harvesting, and primary wood products industry

activities (primary wood products industry is primarily pulp mills and sawmills). The USDA

Forest Service utilizes a rigorous methodology to collect and analyze data, and updates its

statistics on a regular basis. A result is the USDA Forest Service statistics are recognized for

their completeness and reliability. Due to the USDA Forest Service statistics, reliable

information on logging residues and primary wood products industry residues are either directly

available or can be readily derived from it.

However, similar or as complete data or statistics for most, if not all other types of wood residues

or waste are not available from the USDA Forest Service, other government agencies, or other

organizations. These other types can be described as “wood residues and wastes produced in the

secondary wood products industry or further along in the production process.” This material can

be further defined as consisting of two types of wood residues or waste:

• Secondary mill residues, which is produced by secondary wood products industries that

manufacture wood products from lumber, engineered wood products, or wood particles.

Examples include companies that manufacture furniture, doors, cabinets, flooring, pallets,

fences, and building products.

• Urban wood waste, which refers collectively to a wide variety of wood waste present in

commercial, industrial, and municipal solid waste. Examples include used wooden

pallets and shipping containers, wood contained in construction and demolition debris,

used railroad ties, wood commingled with other solid waste, and other types of wood not

included in (or defined as) logging residues, primary wood products industry residues, or

secondary mill residues.

This study focuses on obtaining and reviewing recent national assessments that focus on or

include both secondary mill residues and urban wood waste.

DEFINITIONS

The following terms are used throughout this study:

• Generation refers to the wood waste produced by generators prior to reuse, recycling,

disposal, or other management. Generation does not include “internal” reuse or recycling,

which is reuse or recycling of wood waste before it leaves the generators facility. For

instance, the cutting and reuse of boards broken during the production of large pallets on
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smaller pallets at a pallet manufacturing facility is internal reuse. This definition of

generation is different that that used by some. For instance, the U.S. Environmental

Protection Agency considers generation not to include waste materials that are reused. For

instance, the repair and reuse of used pallets are not included in estimates of MSW

generation.

• Potentially Available refers to the amount of wood waste generated less that used, reused, or

recycled in high value markets, that unavailable due to contamination, and that unavailable

due to commingling with other waste materials.

• High Value Markets refers to industries that manufacture products like pulp, lumber,

engineered wood products (such as particle and fiberboard) and pay a relatively high price

for wood that meets their specification. Overall, it is assumed that wood used by these

markets is not available to woodfuel or other “lower” value markets.

• Green ton is the weight in tons of wood waste in its “as is” state, or including any moisture.

• Dry ton referes to the weight of wood waste in a “bone dry” state, or with no moisture.

• “Assessment” refers to the seven wood waste assessments reviewed and included in this

study.

• “Study” refers to this study. Because this study evaluated seven assessments, some of which

are referred to as studies, there exists significant potential to confuse the seven assessments

with this study. To help reduce confusion, this document is referred to as “this study”.

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SECTION II:

NATIONAL WOOD WASTE ASSESSMENT SUMMARIES

Seven national assessments of wood residues and waste were identified through a rigorous

literature search as meeting the goals of this study as well as possessing a minimum level of

research and analysis. The literature search included interviewing numerous research or

technical staff at federal energy, environmental, and forestry agencies, private consulting firms,

utilities, trade organizations, and others.

The seven assessments were carefully reviewed to obtain a clear understanding of the research

and analysis completed, assumptions made, and conclusions. Detailed summaries of the seven

studies are presented in this section. The results and assumptions contained in the assessments

was “disseminated and reassembled” into estimates of secondary mill residues and urban wood

waste quantities and prices, including that potentially available for fuel. The methodology used

to and results of the “dissemination and reassembly” are presented in Section III.

The assessments reviewed, summarized, and use to estimate national quantities are:

1. Characterization of Building-Related Construction and Demolition Debris in the

United States. U.S. EPA. June 1988,

2. Characterization of Municipal Solid Waste in the United States: 1997 Update. U.S.

EPA. May 1998.

3. Lignocellulosic Feedstock Resource Assessment. NEOS Corporation. September

1998.

4. Urban Tree Residues: Results of the First National Inventory. . September 1994.

5. Urban Wood Waste Resource Assessment. G. Wiltsee. November 1998.

6. Biomass Residue Supply Curves for the United States (Update). Antares Group, Inc.

June 16, 1999

7. “The Changing Solid Waste Wood Resource in the United States, 1990-1998”. David B.

McKeever, USDA Forest Service. For publication in BioCycle Journal of Composting

& Recycling.

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TITLE: Characterization of Building-Related Construction and Demolition Debris in

the United States.

BY: Franklin Associates (under subcontract to TechLaw, Inc.)

Prairie Village, Kansas

FOR: Municipal and Industrial Solid Waste Division

Office of Solid Waste

U.S. Environmental Protection Agency

DATE: June 1998

SUMMARY

Franklin Associates is well known and respected for their work characterizing municipal solid

waste generation, reuse and recycling, and disposal in the U.S. Franklin Associates has been

completing biannual updates for the U.S. EPA for some 10 –15 years. Similar to the

methodology developed for MSW, the construction and demolition (C&D) methodology relies

on “readily available national data” which is suitable for periodic updates. The methodology

utilizes U.S. Census data on C&D activities along with “point source waste assessment data” (i.e.

data on C&D waste generated by specific construction or demolition projects). Overall, it is a

sound methodology, but results in a fair amount of uncertainty due to the reliability of both the

U.S. Census data and application of point source data to national estimates. As stated in the

report, the authors acknowledge this and expect the methodology will be updated and modified

over time to more accurately estimate C&D debris generation.

Overall, the assessment estimates that 136,000,000 tons of building-related C/D debris was

generated throughout the U.S. in 1996. Presented in Table 1 is a summary of the amounts

generated.

TABLE 2-1: Summary of 1996 C&D Generation

Residential Non-Residential Total

Green tons Percent Green Tons Percent Green Tons Percent

Construction 6,500,000 11 4,270,000 6 10,830,000 8

Renovation 31,900,000 55 28,000,000 36 59,900,000 44

Demolition 19,700,000 34 45,100,000 58 64,800,000 48

TOTAL 58,100,000 100 77,370,000 100 135,530,000 100

This assessment reports on six sets of C&D sorting studies, which indicate the wood waste

comprises 14% to 67% of C&D debris. Applying the results of the sorting studies to the amount

of C&D debris generated, an estimated 9,040,000 and 91,120,000 tons of C&D wood waste were

generated nationally in 1996.
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LIMITATIONS OF THIS ASSESSMENT

As the title suggests, this assessment focuses on building-related C&D debris, and does not

include other types of C&D debris such as road and bridge construction and demolition, and land

clearing debris. It is my experience that road and bridge construction does generate some wood

waste, but is relatively small compared to the amount of other types of C&D debris generated,

such as concrete, asphalt, steel, dirt or soil, etc. It is likely the amount of wood waste generated

by road and bridge construction, repair, and demolition is relatively small compared to the

amount generated by building-related C&D activities.

The assessment relies on U.S. Census data on C&D related activities, and then applies this data

to assumed C&D debris generation rates. This methodology ignores any local, state, or regional

factors that affect the amount actually generated. As the authors acknowledge, this lends

uncertainty to the results. However, the purpose of the assessment was to estimate C&D debris

on a nation basis using a methodology that permits periodic updates as the national data or

assumption are updated. The assessment was not an attempt to conduct more detailed state or

regional C&D debris assessments. Based on the goals of the assessment, the methodology and

assumption are sound and appropriate.

The lack of land clearing debris is truly a liability, since not including this material results in

significant under-estimation of the amount of wood waste available. Land clearing debris is

comprised mostly (if not only) of wood and may be a significant component of C&D debris.

Based on studies completed by C.T. Donovan Associates, Inc. on C&D debris generation,

reuse/recycling, and disposal in Rhode Island and Vermont, the amount of land clearing debris in

C&D debris ranges from about 7% to 20% respectively. Please note the Vermont percentage

may be high, since the methodology used to estimate wood waste generation appears to have

relied heavily on estimates of wood generated by land clearing activities and under-estimated

wood waste generated by other C&D activities.

WHY INCLUDE THIS ASSESSMENT?

Many have long argued that C&D wood waste is a significant, appropriate (if properly

processed), and available source of wood fuel. At least two wood-fired power plants in the U.S.

have been specifically permitted to use C&D wood, and various other use clean, untreated

woodfuel separated from C&D debris.

This assessment is one of two national assessment I am aware of that estimates C&D debris

generation as well as recycling and disposal in the U.S. The other is that completed by David

McKeever, the results of which are presented in “The Changing Solid Waste Wood Resource in

the United States, 1990-1998” to be published in BioCycle Journal of Composting &

Recycling. Both this assessment and that used by McKeever to estimate construction and

renovation C&D debris are similar. One could argue that the methodology is not perfect, that

local, state, and regional factors have a large effect on the amount of C&D debris actually

generated, recycled, and disposed, and that not including land clearing debris means a significant

amount of wood waste is not included in the assessment. While this is true, it is also true that
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this peer-reviewed assessment uses a sound methodology and the best available data to estimate

C&D debris and wood waste.

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TITLE: Characterization of Municipal Solid Waste in the United States: 1997 Update

BY: Franklin Associates

Prairie Village, Kansas

FOR: Municipal and Industrial Solid Waste Division

Office of Solid Waste

U.S. Environmental Protection Agency

DATE: May 1998

SUMMARY

For some 10-15 years, Franklin Associates has assisted the U.S. EPA identify the types and

amounts of municipal solid waste (MSW) generated, recycled, and disposed in the U.S. and has

published a series of annual or biannual updates. These “characterization studies” have gained

wide acceptance are regarded as one of, if not the key resource regarding overall MSW

generation, recycling, and disposal in the U.S.

The approach used in the assessment is a “material flows methodology”, which relies on

manufacturing or production data for both durable and non-durable goods to estimate the amount

of MSW entering the waste stream. This methodology adjusts production data to account for

product life and for the import and export of products.

The material flow methodology is not the only methodology that could be used to estimate MSW

quantities. The authors discuss using “site-specific” sampling, sorting, and weighing data, but

dismiss this methodology due to both the lack of data across the U.S., and the uncertainty that

will result when using limited data to project national estimates. Just as important, the materials

flow methodology allows estimates to be updated relatively easily as new national

manufacturing, production, product life, or import/export data becomes available.

Since some materials in MSW cannot be quantified by this approach (such as yard waste, for

which there is no production data), quantification of these materials is based on data from waste

characterization studies.

It is important to note that this assessment quantifies or characterizes the MSW portion of the

total solid waste stream. Other types of solid waste, such as industrial process wastes, hazardous

wastes, construction and demolition wastes, agricultural wastes, natural resource extraction

wastes are not included. The authors characterize MSW as durable goods, nondurable goods,

containers and packaging, food wastes, and yard trimmings, which are generated by residential,

commercial, institutional, and industrial (packaging and administrative, but not process waste)

sources. Wood is clearly a material found in MSW as wood packaging (pallets and shipping

containers), furniture, and other miscellaneous products, as well as in yard waste.
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Urban Wood Waste Quantities in the U.S.

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According to the 1997 Update, the total MSW generation in the U.S. was just under 210,000,000

tons. Of this amount, wood accounted for 5.2%, or just under 11,000,000 tons. Yard waste

accounted for 13.4%, or 28,000,000 tons. For wood waste, 4.5% or 490,000 tons was recovered

or recycled in some way, while the remaining 95.5% or about 10,500,000 tons was disposed.

For yard waste the amount recovered or recycled was 38.6% or just under 11,000,000 tons, and

the amount disposed was 61.4%, or about 17,000,000 tons.

Used pallets and MSW wood are typically classified together as urban wood waste. Used pallets

are generated by many different types of commercial and industrial businesses, and may be

managed as either municipal or industrial solid waste. This has lead to some confusion about

whether estimates of MSW wood waste include used pallets. The 1997 Update does include

used pallets, and incorporates the data on pallet production for the Wooden Pallet and Container

Association as well as data on used pallet generation, reuse and recycling, and disposal from

research completed by Robert Bush, Philip Araman, and Vijay Reddy.

Data published by Bush et al indicate that in 1995, 223,000,000 pallets, or 6,140,000 tons were

taken to MSW or C&D landfills. Of this amount, 17%, or about 1,044,000 tons were recovered,

mostly for low value uses or products like mulch and fuel. The remaining 83%, or 5,096,000

tons were disposed.

According to the 1997 Update, 200,000,000 used pallets, or over 5,000,000 tons were are

repaired or refurbished and returned to service in 1996. This quantity is in addition to the

quantity of used pallets taken to landfills. Since pallet repair and refurbishing is considered reuse

(and not recycling), this quantity is not included in estimates of pallet or MSW generation or

recycling presented in the 1997 Update. In addition, the amount of used pallets and other types

of wood waste (and other types of MSW) used as fuel is not considered recycling.

LIMITATIONS OF THIS ASSESSMENT

There are no significant limitations with this assessment, and the methodology used is

appropriate to estimate the amount of wood waste in MSW. An assumption used in the

methodology is that “source reduction” is prior to generation. The definition of source reduction

used in the 1997 Update includes reuse of a material in its current form. An example is

refurbishing used pallets so that they can be reused as pallets. Not including source reduction

means waste materials that are managed by source reduction activities are not included in

estimates of either generation or recycling. This is important because not including source

reduction of wood waste may undercount the amount potential available for fuel. Wood waste

managed by source reduction activities might be diverted to fuel markets if these markets

existed. However, this is judged to be a minor issue since wood waste managed by source

reduction activities will likely have much higher value than that processed into fuel. This

indicates little, if any wood waste managed by source reduction activities will be available to fuel

or other low value markets.
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WHY INCLUDE THIS ASSESSMENT?

Overall, the 1997 Update is the most comprehensive estimate of national MSW generation,

recycling, and disposal available. The methodology used is sound, and permits a defensible

estimate of the amount of wood waste in MSW as well as the amount potentially available as

fuel.

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TITLE: Lignocellulosic Feedstock Resource Assessment

BY: Timothy Rooney

NEOS Corporation

Lakewood, Colorado

FOR: Art Wiselogel, Technical Monitor

National Renewable Energy Laboratory

DATE: September 1998

SUMMARY

This assessment is a “macro-level screening tool” which evaluates various lignocellulosic

materials with potential for conversion to ethanol for use as a motor fuel. It contains state-level

resource generation and availability information on 13 different biomass feedstocks. Five of the

feedstocks are wood based, and are:

• Primary wood products industry (termed “primary mills”) hardwood residues;

• Primary mill softwood residues;

• Secondary wood products industry (termed “secondary mills”) hardwood residues;

• Secondary mill softwood residues; and

• Urban tree residue (UTR).

The NRBP study focuses on secondary wood products industry residues or wood waste

produced further along in the production. The materials included in the Lignocellulosic

Feedstock assessment that are of interest to the NRBP study are the hard and softwood

secondary mill residues and urban tree residues.

The author notes that good data on secondary mill residue generation and availability is not

readably available through agencies that track wood products industries trends such as the U.S.

Forest Service, state agencies, or others. The USDA Forest Service, other government agencies,

or industry associations do not compile the types of data for secondary mills that allows

calculation or projection of residue quantities. This is very different than primary mill residues,

which the USDA Forest Service does compile data as part of the 1974 Resource Planning Act.

Because of the lack of data, the author developed a methodology to estimate state-level

secondary mill residue quantities. The methodology utilizes per mill generation factors and

1992 U.S. Bureau of Census data on secondary mills in each state. The per mill generation

factors are based on Minnesota Wood Waste Studies: One Man’s Waste is Another Man’s

Gold (Minnesota Wood Waste Studies) published by the Minnesota Department of Natural

Resources in 1994. Based on the Minnesota Wood Waste Studies, the author was able to

estimate the average amount of residues secondary mills with a specified range of employees

generate (for instance, secondary mills with 10 to 19 employees generate on average 280 dry
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Urban Wood Waste Quantities in the U.S.

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tons/mill/year). State-level quantities were calculated by multiplying the number of secondary

mills with a certain range of employees by the appropriate generation factor. Quantities of

hardwood versus softwood residues were estimated based on U.S.D.A. Forest Service data on

primary wood product industry resides, which is assumed to be representative of secondary mill

residues.

Data from Minnesota Wood Waste Studies was also used to estimate the amount of secondary

mill residues that are either unused and can be recovered (as a feedstock for ethanol) or used by

“non-captive” markets. Non-captive markets are markets that utilize secondary mill residues,

but the prices paid indicate the residuals could be diverted to ethanol plants if such plants

existed. For instance, pulp markets are assumed to be a “captive” market since it is assumed

prices paid for pulp chips will likely exceed the prices paid by ethanol plants. The end uses for

secondary mill residues management are presented in Table 2.

TABLE 2-2: End uses of Secondary Mill Residues

End Use

Amount

(Percent)

Fuel, sold or given away 17.3

Fuel, used on site 20.7

Animal bedding 26.2

Mulch 4.1

Pulp and engineered wood products 2.8

Other 1.8

Landfilled or disposed as solid waste 17.2

TOTAL 100.1

Based on secondary mill residue end uses presented in Minnesota Wood Waste Studies, the

author assumes that 36% of secondary mill residues currently used are sold in non-captive

markets, and that 50% of unused residues are not available due to contamination, quality, or

recoverability.

The assessment includes information on secondary mill residue prices, which are presented as

statewide averages. Little information is presented on the source of the price data, other than it

is from the U.S. DOE Energy Information Agency.

The results for secondary mill residues generated in the U.S. are presented in Table 2-3. The

conversion to green tons assumes UTRs have a moisture content of 20%. Overall, 39% of

UTRs are either used in non-captive markets or that are unused and recoverable ((3,627,800 +

1,219,100)/12,515,300 = 39%).
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TABLE 2-3: Secondary Mill Residues

Generation

(Dry tons/yr)

Price

(Dry tons/yr)

Used by NonCaptive Markets

(Dry tons/yr)

Unused and

Recoverable

(Dry tons/yr)

Hardwood 4,827,200 $20.10 1,407,300 459,100

Softwood 7,688,100 $20.03 2,220,500 760,000

TOTAL (dry tons) 12,515,300 3,627,800 1,219,100

TOTAL (green tons) 15,644,125 4,534,750 1,523,875

The data and information on UTR is from Urban Tree Residues: Results of the First National

Inventory, Final Report completed by NEOS for the International Society of Arboriculture

Research Trust and others in September 1994. The Urban Tree Residue assessment is

discussed is a separate summary.

LIMITATIONS OF THIS ASSESSMENT

The key limitation regarding secondary mill residue is the methodology used to estimate

quantities. The methodology used is appropriate and is relatively accurate in estimating wood

residue quantities. The same methodology (applying per mill or per employee generation factors

to employment data) has been successfully used by others (such as C.T. Donovan Associates,

Inc.).

However, a key issue regarding accuracy is the assumptions regarding per mill generation

factors. The author relies on data from Minnesota, which may or may not represent national

trends for secondary mills. Secondary mills include a broad range of industries that utilize

various types of wood products as feedstock and technologies to convert the resources into

products. This implies residue generation factors, whether per employee, per mill, per boardfeet

of wood feedstock, etc. will vary significantly. Included as secondary mills are Standard

Industrial Classifications (SIC) codes 2426 to 2499 and 2511 to 2519, and nationally there are

about 89,000 establishments within these SIC codes. The large number of secondary mills

further suggests there is significant variability in residue generator factors. One issue the author

does not address is how conservative are the various assumptions that have been made. For

instance, have assumptions been made so that the results will under-estimate (versus overestimate) residue generation or availability. However, methodologies that estimate quantities

based on SIC codes are likely to underestimate quantities. This is because it is very difficult to

identify and/or include all establishments that one is interested in, which leads to underestimates

of national quantities.

The author assumes that 36% of secondary mill residues currently used are used in non-captive

markets. This assumption may slightly overestimate the amount potentially available for fuel.

Presented in Table 3 is an analysis of the amount of secondary mill residue used by non-captive

markets, based on data presented in Minnesota Wood Waste Studies. The results of this

analysis indicate that only 29.4% of secondary mill residues currently used are used by non-
Secondary Mill Residues &

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18

captive markets. However, the difference between what the author assumed and that developed

in Table 2-4 is relatively small considering the variability in the data and that actually available

as fuel. The assumption that 50% of unused residues are not available due to contamination,

quality, or recoverability appears reasonable.

TABLE: 2-4: Analysis of Secondary Mill Residue Uses

End Use

Amount

(Percent)

Amount Used by

Non-Captive

Markets

(Percent) Comments

Fuel, sold or given away 17.3

17.3 All since already sold or

given away as fuel

Fuel, used on site 20.7

0 Little or none since

valuable to generator as

fuel

Animal bedding 26.2

0 Little or none since high

value market

Mulch 4.1

4.1 All since fuel markets

can compete with mulch

markets

Pulp and engineered wood products 2.8

0 Little or none since high

value market

Other 1.8

0 None since assumed not

available

TOTAL 72.9% 21.4%

PERCENT OF TOTAL 21.4/72.9 = 29.4%

Limitations associated with urban tree residues are discussed in the summary of the Urban Tree

Residues: Results of the First National Inventory, Final Report.

WHY INCLUDE THIS ASSESSMENT?

To my knowledge, no other national wood waste assessments utilizes a similar methodology or

one that produces similar results to estimate quantities of secondary mill residues. Despite

concerns over generation factors and other assumptions, I believe the methodology used is both

sound and appropriate, and for the purposes of a national assessment of secondary mill residues,

it is the best methodology to use.
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TITLE: Urban Tree Residues: Results of the First National Inventory

BY: NEOS Corporation

Lakewood, Colorado

FOR: International Society of Arboriculture Research Trust

Allegheny Power Service Corporation

National Arborist Foundation

DATE: September 1994

Summary

Yard waste is recognized as the second largest component of municipal solid waste (see

Characterization of Municipal Solid Waste in the United States: 1997 Update), but accurate

and comprehensive data on the quantities generated is lacking. This assessment is an attempt to

quantify “urban tree and landscape residue” (UTR) generated in the contiguous 48 states.

UTR is loosely defined as “green” materials generated by urban forestry-related businesses. The

components of UTR include:

• Wood, including chips, logs, tops and brush, mixed wood (combination of logs, whole

tops, and brush), and whole stumps;

• Leaves collected during seasonal leaf collection; and

• Grass clipping.

Although seasonal leaf collection and grass clippings are included in this assessment, these

materials are not wood and are of limited value as fuel. Because of this, both materials will not

be included in this study.

The methodology used to quantify UTR was to conduct telephone and mail surveys of UTR

generators throughout the U.S., and to extrapolate the survey data to estimate national UTR

quantities. The authors identified a total of nine groups or types of entities that generate UTRs.

The groups are:

• Commercial tree care firms;

• Municipal/county park and recreation departments;

• Municipal tree care divisions;

• County tree care divisions;

• Electric utility power line maintenance;

• Nurseries;

• Landscapers and landscape maintenance;

• Excavators and land clearing; and

• Orchards
Secondary Mill Residues &

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20

Although orchards are a significant generator of UTR, orchard residues are not included in the

assessment. This is because the survey of orchards produced a low response and meaningful

data was not obtained.

The number of surveys mailed was relatively large (3,878 surveys were mailed), and the

response rate was excellent (a total of 44% of the surveys were returned, and 1,330 surveys, or

34% were useable). Since the methodology relies on extrapolating the survey results to national

quantities based on the total number of UTR generators, significant research went into

identifying the total number of generators within each group.

It is important to note the survey was of UTR generators, and as such the results also focus on

UTR generation. However, good information was also obtained through the survey on UTR end

uses, management, and disposal. No attempt was made to verify or independently estimate the

amounts of UTR recycled or disposed through end users or disposal options.

The assessment concludes that just over 200,000,000 cubic yards of UTRs were generated in the

U.S. in 1994. Of this amount, just over 194,000,000 cubic yards of UTR wood waste (i.e. not

including seasonal leaf collection and grass clippings) were generated. A summary of the

estimates is presented in Table 2-5. In addition, the assessment states that just over 2,000,000

cubic yards of “natural disaster” (i.e. generated by strong wind and storms, hurricanes, ice, etc.)

UTR is generated. It is not explicitly stated whether the natural disaster amount is an annual

average or is the amount generated in 1994. It is believed the national estimate of UTR

generation includes natural disaster UTR. It is also not explicitly stated what natural disaster

UTR consists of (whether wood, leaves, grass clipping, or a mixture), but it is reasonable to

assume it consists primarily of wood.

TABLE 2-5: Estimate of 1994 UTR Wood Waste Generation in the U.S.

Amount

Urban Tree Residue

All UTRs

(cubic yards)

UTR Wood Waste

(cubic yards)

Chips 134,352,000 134,352,000

Unchipped logs 30,078,000 30,078,000

Unchipped tops and brush 16,042,000 16,042,000

Unchipped mixed wood 12,031,000 12,031,000

Fall leaves 4,010,000 0

Grass clippings 4,010,000 0

Whole stumps 2,005,000 2,005,000

TOTAL 202,528,000 194,508,000

One issue with this assessment is units, woodfuels are typically reported based on weight (i.e.

tons) and not volume (i.e. cubic yards). In order to convert from volume to weight, one needs to

know the density of the material in question. In Lignocellulosic Feedstock Resource
Secondary Mill Residues &

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21

Assessment, the author provides “conversion factors” (i.e. densities) which were used to convert

UTR volumes to weight. The various densities and conversion of UTR wood waste volumes to

weight is presented in Table 2-6.

TABLE 2-6: Conversion of 1994 UTR Wood Waste Volumes to Weight

UTR Wood Waste

Generation

(cubic yards)

Density

(green tons/cubic yard)

Generation(a)

(tons)

Chips 134,352,000 0.30 40,306,000

Unchipped logs 30,078,000 0.40 12,031,000

Unchipped tops and brush 16,042,000 0.17 2,727,000

Unchipped mixed wood 12,031,000 0.20 2,406,000

Whole stumps 2,005,000 0.50 1,002,000

TOTAL 194,508,000 58,472,000

(a): The amount of generation calculated has been rounded to the nearest thousand tons.

In terms of UTR management, the assessment states that for types of UTR combined:

• 42% is given away;

• 17% is landfilled;

• 12% is sold (to boiler fuel, compost, mulch, wood products manufacturing, cordwood,

and other markets)

• 11% is left on-site;

• 6% is sent to recyclers;

• 3% is burned for energy (assumed to be by the generator); and

• The remaining 9% is open burned, stockpiled, incinerated, or managed in other ways.

The information on UTR management indicates that up to 88% of UTRs generation is potentially

available for fuel or other uses. Presented in Table 2-7 an analysis of UTR management and

calculation of that potentially available.

LIMITATIONS OF THIS ASSESSMENT

As the authors acknowledge, the methodology used in the assessment is both sound and well

carried out, but there are a few “disappointments” (or liabilities) in the results. The authors note

two key liabilities: the inability of industry personnel to accurately estimate UTR quantities and

the level of accuracy in national estimates due to large data variations in the survey results. Both

of these limitations are significant.

There are at least two other important liabilities. The first is units. Volume can easily be

converted to weight based on density, if the density is known. But UTR density can vary
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

22

TABLE 2-7: Analysis of UTRs Potentially Available for Fuel

UTR Management

Amount

(% of generation)

Assumption Regarding

Availability

Amount Potentially

Available

(% of generation)

Given away 42 All is available 42

Landfilled 17 All is available 17

Sold 12 1⁄2 is available 6

Left on-site 11 All is available 11

Sent to recyclers 6 None is available 0

Burned for energy 3 All is available 3

Open burned, etc. 9 All is available 9

TOTAL 100% 88%

significantly depending on UTR type (i.e. chips, logs, tops and brush, mixed wood, and whole

stumps), wood species, moisture content, how the UTR was/is collected, processed, and/or

stored, and other factors.

The second is that the survey date was extrapolated into national quantities based on the number

of entities that generate UTR. The number of entities is a valid parameter (to extrapolate this

type of data), but the results likely less accurate than if other parameters had been used. For

instance, both small and large companies are classified as one entity, but it is likely the larger

company with more equipment and employees will generated more UTRs. The results would

likely be more accurate if another parameter, such as the number of employees. The number of

employees is a better indication of a company’s size and potential for UTR generation, and has

been successfully used in various national biomass resource assessments.

WHY INCLUDE THIS ASSESSMENT

This assessment is not only the most comprehensive, but also the only national urban tree residue

assessment. The methodology used is sound and well carried out, and despite the limitations

discussed above, the results will allow reasonable and defensible estimates of various types of

residues generated (and potentially available as fuel) by commercial and municipal tree care,

utility power line maintenance, and land clearing activities.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

23

TITLE: Urban Wood Waste Resource Assessment

BY: George Wiltsee

Appel Consultants, Inc.

Valencia, California

FOR: K. Shane Tyson, Technical Monitor

National Renewable Energy Laboratory

DATE: November 1998

SUMMARY

This is a very interesting and unique assessment. The assessment estimates the quantity, end

uses, and supply curves for three types of urban wood wastes in 30 randomly selected

metropolitan areas (as defined by the U.S. Office of Management and Budget) in the contiguous

48 states. The three urban wood wastes are:

• Wood waste in municipal solid waste;

• Industrial wood waste; and

• Construction and demolition wood waste.

What is unique about this assessment is the methodology used. The author traveled to each

metropolitan area and spent 2 to 5 days doing telephone research/interviews (mostly from hotel

rooms!) and conducting site visits. The telephone research included government solid

waste/recycling agencies, economic development agencies, chambers of commerce as well as

both public- and private sector entities involved in wood waste generation, collection,

processing, and disposal. The purpose of the research/interviews and site visits was to obtain

representative information on the amounts, management or disposal options, and associated price

or cost for the three types of urban wood waste. Traveling to each area combined with the site

visits provided the author with an “on-the-ground” perspective of the area. A consistent

telephone research/interview and site visit methodology was used for each metropolitan area.

The author used the data collected by telephone research/interviews, site visits, and numerous

“estimating techniques” developed over the course of the project to estimate the quantity of

urban wood waste in each metropolitan area. The 30 areas were completed in sets of five, and

after each set was completed it was submitted to the NREL technical monitor (K. Shane Tyson)

for feedback and redirection. Once all research, interviews, site visits, and technical reviews

were completed, all data was re-reviewed and modified as needed to insure both the data used

and analysis was as consistent as possible for all metropolitan areas.

For each metropolitan area as well as the combined 30 metropolitan areas, the assessment

provides estimates of MSW wood waste, industrial wood, and C/D wood “resources” (believed

to be equivalent to generation) as well as estimates of the quantities utilized by end use markets
Secondary Mill Residues &

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24

and quantities disposed. The information on quantities combined with price/cost information

was used to create supply curves for both each metropolitan area as well as the combined 30

areas.

Not surprising, urban wood waste resources in the 30 metropolitan areas varied significantly.

However, based on data from 28 areas (two “outlier” areas with data irregularities were

disregarded), the author was able to develop a “predictive equation” to estimate urban wood

resources in metropolitan areas. The predictive equation can be used to project the urban wood

waste quantities for all metropolitan areas in the U.S. The author reports that in 1990, there were

281 areas within the U.S. that met the U.S. Office of Management and Budget (U.S. OMB)

definition of a metropolitan area and that the population within the 281 metropolitan areas was

193,007,670. Presented in Table 2-8 is the predictive equation as well as the results of applying

the equation to the total population within metropolitan areas. It is important to note the amounts

shown in Table 2-8 are not for the entire U.S., but instead for the 281 metropolitan areas within

the U.S. The assessment also includes a projected urban wood waste resource supply curve for

all metropolitan areas in the U.S. The author projects the total urban wood waste resource (in all

281 areas) is slightly over 64 million tons per year. The curve suggests that 95%, or 60.8 million

tons are available at a “price” of $0/ton or less (i.e. negative cost). The remaining 5%, or 3.2

million tons are available at a “price” ranging from $3 to $24/ton.

TABLE: 2-8: Urban Wood Wastes Predictive Equation and Generation in the U.S.(a)

Wood Waste Type

Predictive Equation

(tons/yr/capita)

Generation(b)

(tons/yr)

MSW Wood 0.203 39,181,000

Industrial Wood 0.039 7,527,000

C/D Wood 0.091 17,564,000

TOTAL 0.333 64,272,000

(a) Based on a 1990 population in the 281 metropolitan areas of 193,007,670.

(b) Estimates of urban wood waste generation have been rounded to the nearest thousand tons.

LIMITATIONS OF THIS ASSESSMENT

There are few if any significant limitations in the methodology used in this assessment. Overall,

the research and analysis used are ideal for completing local resource assessments. Furthermore,

I have completed numerous local resource assessments myself, I am very cognizant of the need

for and benefit of an “on-the-ground” perspective (I use the term “local flavor”). I am also

convinced the author appropriately combined the 30 separate resource assessments into one

national urban wood waste resource assessment.

However, I do have two concerns. One concern is the supply curves, and how they will or

should be used. As the author notes, the supply curves are created by assembling data on both

quantities and cost to wood waste generators to manage their wood waste. My concern is that

some may interpret the supply curves as urban wood waste availability (for fuel or other uses)
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

25

curves, which they are not. The reason the supply curves do not reflect availability is the data

used to create the curves do not take into account the various factors that affect availability, such

as processing costs and transportation. To illustrate, consider wood given or left by tree care

companies to the landowner after trimming or removing his/her trees. This wood is considered

to have a cost of $0/ton, since there is no cost to the company to manage it. But, this cost is not

indicative of the price a power plant would need to pay for the same wood. In order to be

delivered to the power plant, the tree care company or another entity would likely need to

process (i.e. chip and screen) and transport the wood, both of which are costs and will need to be

recovered in the price charged to the power plant.

The other concern is the completeness of the individual resource assessments done in each

metropolitan area. I have completed numerous local resource assessments, and I am well aware

of the time it takes to complete the research. The time is not measured just in hours spent doing

research, but also how long it takes to locate the right people (to obtain the information you

need), for some people to call back, for leads to be developed, etc. My concern is that the

individual resource assessments needed to be completed in a relatively short amount of time, and

that this resulted in some sources and quantities of urban wood waste not being identified. The

overall result is that the individual and national assessments may underestimate the amount

actually generated. Please note this is not a criticism of this assessment, and in fact the issue of

undercounting resources is an inherent concern of all biomass assessments.

A minor limitation of the assessment is only areas that meet U.S. Office of Management and

Budget definition of a “metropolitan area” are included in the assessment. There are many towns

and perhaps cities that generate urban wood waste, but are not accounted for in the assessment

(since they do not meet the OMB definition). The means the national urban wood waste

estimates and supply curves actually underestimates total quantities. Again, this is not meant to

be a criticism, but this limitation should be recognized when using the information in the

assessment.

WHY INCLUDE THIS ASSESSMENT

I believe this assessment is one of the most comprehensive and useful assessments of urban

wood waste completed to date, both from the national perspective, but also from the perspective

of local influences on wood waste generation and management. I firmly believe the

methodology used, and in particularly the site visits, provide a heightened understanding and

awareness of both the resource and how it is managed. The end result is increased confidence

and reliability of both the data and the analysis.
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26

TITLE: Biomass Residue Supply Curves for the United States (Update)

BY: Antares Group, Inc.

Landover, Maryland

FOR: U.S. Department of Energy’s Biomass Power Program

National Renewable Energy Laboratory

DATE: June 16, 1999

SUMMARY

This assessment was completed at the request of both the U.S. Department of Energy and the

National Renewable Energy Laboratory. The goal of the assessment was to provide the Energy

Information Agency (EIA) with credible and defensible information on wood residue and waste

supply and costs for use in national energy modeling efforts. In order for EIA modelers to be

comfortable with the data, when assumptions were required, conservative assumptions were

made. The goal was accomplished, and for the first time ever biomass was included in EIA’s

energy models for the Annual Energy Outlook 1999 report. Previously, biomass was

treated outside EIS’s models and consequently the full role of biomass as an energy source in the

U.S. was not presented. This assessment is also presently being used by a several corporate

interests for their biopower market investigations, and by the Electric Power Research Institute

EPRI for climate change modeling efforts.

This assessment develops supply curves for the portion of seven types of wood waste that are

considered to be “available”. Available is defined as “not currently destined for other productive

uses.” The seven types of wood waste are:

• Forest wood residues, which includes both silvicultural and site conversion wood waste;

• Bark residues from primary wood product industries (“primary mills”);

• Wood residues from primary mills;

• Construction wood waste;

• Demolition wood waste;

• Woody yard trimmings; and

• Other wood waste, which includes pallets, shipping containers, secondary wood products

industry wood residues, industrial wood waste, and wood in municipal solid waste (MSW

wood).

Of interest to this study are construction wood waste, demolition wood waste, woody yard

trimmings, and other wood waste.

Supply curves are developed for each state, as well as the five biomass energy program regions,

15 electric supply regions, and the U.S. as a whole.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

27

The supply curves of available wood waste were developed using a unique methodology. The

methodology uses state-level information on available wood waste quantities and projects the

“delivered residue cost” (DRC) based on disposal (in landfills), collection and processing, and

transportation costs. The DRC is estimated as follows:

DRC = RPC + RTC - 1⁄2(LFT)

Where:

RPC = Average collection and processing cost, which vary for the 7 types of wood wastes.

RTC = Transportation cost, which vary depending on one of four assumed transportation distances and state

specific transportation cost index.

LFT = Average cost to disposed solid waste in landfills (i.e. “tipping fee”), which vary depending on the state.

When available, state-specific data was used to quantify the amount of available wood waste in

each state. For instance, information on available wood waste in each of the 11 states in the

Northeast Regional Biomass Program (NRBP) is from The Potential for Producing Ethanol

from Biomass in the Northeast by C.T. Donovan Associates, Inc. and published by the NRBP

in September 1994. If state-specific data was not available, then national data was used and the

state quantity calculated based on a factor that closely tracks the activity that produces the

material. For instance, state construction wood waste estimates are based on number of housing

starts in the state compared to the national housing starts. The various factors used for each

wood waste type are presented in Table 2-9. In general, national estimates of available wood

waste are based on work done by David McKeever of the U.S.D.A. Forest Service, Forest

Products Laboratory.

TABLE 2-9: Factors Used to Estimate State Quantities and Wood Waste Collection and

Processing Costs

Wood Waste Type Factor Collection and Processing Cost

Forest residues Timber Harvest $17/green ton

Bark Timber Harvest $4/green ton

Primary mill

residues

Timber Harvest $4/green ton

Construction Housing Starts $12/green ton

Demolition Population $12/green ton

Yard waste MSW $12/green ton

Other MSW $12/green ton

Collection and processing costs for the seven types of wood wastes were obtained from several

published sources, and the average value was used to calculate the DRC. A summary of the

collection and processing costs are presented in Table 2-9.

All available wood waste is assumed to be within 100 miles of potential power plant sites, and

transportation costs are based on four assumed transportation distances: 25, 50, 75, and 100
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

28

miles. In some states, a maximum transportation distance of 100 miles does not make sense due

to the size of the state. In smaller states (less than 31,416 square miles, the area of a 100 mile

radius circle), the maximum transportation distance was adjusted downward. The authors

researched freight costs, and a national freight cost of 24.11¢/mile is used, and was derived from

national statistics on local (non-intercity) freight costs. The freight cost in each state was

adjusted based on U.S. Department of Commerce transportation cost index. For wood waste that

tends to be generated in rural settings (forest residues, bark, and primary mill residues) the state’s

lowest transportation index was used. For wood waste tending to be generated in urban settings

(construction wood waste, demolition wood waste, yard waste, and other wood waste), the index

for the major city (in the state) was used.

For the wood waste types that are commonly disposed in landfills (i.e. construction wood waste,

demolition wood waste, yard waste, and other wood waste), it is assumed that wood waste

processors/recyclers will charge a tipping fee that is one-half of the fee charged to dispose

municipal solid waste in landfills. The reduced fee reflects a financial incentive

processors/recyclers will charge to divert wood waste from landfills to their facilities. The statespecific tipping fee used is the state average, and is based on data published in the magazine

Solid Waste Digest in 1998. For wood waste that is not typically landfilled (i.e. forestry

residues, bark, and primary mill residues), no tipping fee is assumed (i.e. $0/ton).

For each state, a total of 28 data points (seven wood waste types

and four transportation distances) were calculated and used to plot

the state supply curve. Each data point consists or is the product

of both a wood waste quantity and the corresponding DRC. The

state-level quantity of each wood waste type was “allocated” to the

four transportation distances based on area (of a circle with a

radius equal to the transportation distance).

In some cases, the assumed fee charged by processors/recyclers

(i.e. one-half of the state average landfill tipping fee) exceeds the collection, processing, and

transportation cost, resulting in a negative DRC. A negative DRC implies power plants are paid

to accept processed wood waste as fuel, which is unrealistic. It is assumed that the minimum

price power plants will pay for woodfuel is 50¢/million Btu (MMBtu), and a “market floor price”

of 50¢/MMBtus is assumed in all supply curves.

The data used to create the state supply curves is aggregated together to create a national supply

curve and supply curves for the five regional biomass programs. Supply curves are also created

for the 15 electric supply regions, but since some of these regions include portions of states,

“mapping factors” were used to adjust the state-specific data for use in the regional supply

curves. Mapping factors are the area a specific supply region occupies in a state divided by the

total area of the state.

As shown in Table 2-10, this assessment concludes that just over 111,000,000 green tons/year of

all types of wood residues and wastes are available in the U.S. (i.e. “not currently destined for

other productive uses”). The study further concludes that of this amount:

Allocation of Wood Waste

Quantities

Transportation

Distance

Quantity

(% Of Total)

25 miles 6

50 miles 19

75 miles 31

100 miles 44

100%
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

29

• 34%, or about 38 million tons/year are low cost residues (< $1.00/MMBtu) consisting of

construction wood waste, demolition wood waste, yard waste, and other waste wood;

• 6%, or about 7 million tons/year are medium cost residues ($1.00 to $3.00/MMBtu)

consisting of primary mill residues and bark;

• 60%, or about 67 million tons/year are high cost residues ($2.50 to $5.00/MMBtu)

consisting of forestry residuals.

TABLE 2-10: Wood Residues and Wastes Potentially Available for Fuel

Wood Waste

Amount Potentially Available

(tons)

Silviculture/site conversion 72,192,000

Primary mill bark residues 1,956,000

Primary mill residues 6,015,000

Woody yard trimmings 10,123,000

Construction residues 6,238,000

Demolition residues 7,864,000

Other wood wastes(a) 6,759,000

TOTAL 111,147,000

(a) Includes some, but not all secondary mill residues.

LIMITATIONS OF THIS ASSESSMENT

This assessment offers a very innovative approach and methodology to developing national and

regional biomass supply curves I am aware of. However, embedded in the methodology are two

assumptions that lead to underestimation of the available wood waste resource. The first is little,

if any available secondary wood products industry (“secondary mill”) wood waste is accounted

for by the methodology. The authors acknowledge that secondary mill residues are

underestimated in the assessment. Secondary mill residues are not addressed as a separate wood

waste type, but instead are assumed to be a part of “other wood waste” which is essentially MSW

wood waste (i.e. wood waste managed as municipal solid waste). Estimates of MSW will likely

include only a fraction of the amount of secondary mill residues actually produced, since

secondary mill residues are managed as industrial waste and not as MSW (although in some

cases it may be). The amount of available secondary mill residue could be significant. The

assessment Lignocellulosic Feedstock Resource Assessment completed by NEOS Corporation

for the National Renewable Energy Laboratory in September 1998 (see attached summary)

conservatively estimates the amount of “unused and recoverable” (similar to the definition of

“available” used in this assessment) secondary mill residues at about 1.2 million tons/year.

The second is the implicit assumption in the assessment that “energy production uses will not

compete for materials already used productively.” While this is a valid and likely necessary

assumption to make, but it also means that a great reservoir of potentially low cost woodfuel is
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

30

not addressed. If and when woodfuel markets expand, it is reasonable to expect wood waste will

be diverted from low value markets (such as landfill cover, compost amendment, and mulch) to

fuel markets due to economic and other factors or benefits. It is not possible to estimate how

much wood would be diverted, but it does not seem unreasonable to assume it is roughly

equivalent to the low cost residues estimated in this assessment.

A concern I have about the methodology used is the “delivered residual cost” (DRC), which is

determined using the identical formula for all residuals in all states. This means a rigid

procedure is used to estimate a very dynamic and in some cases volatile parameter. Factors such

as the centralized biomass resources (which occurs in many areas and may greatly impact

transportation costs), landfill bans (on yard waste and other types of clean, untreated wood),

logging restrictions, and other market dynamics (a good example is the demise of biomass power

plants in the Northeast and California) are not incorporated into the methodology and thus can

not affect the results. The end result of the methodology’s “inflexibility” is of more concern in

the state and regional supply curves and less of a concern in the national supply curve. It would

be very interesting to run some “sensitivity analysis”, that is vary the collection, processing,

transportation, and disposal costs to reflect state or regional trends or factors, and observe what

the impact is on the state, regional, and national supply curves.

WHY INCLUDE THIS ASSESSMENT?

Without a doubt, this assessment is one of the most important analyses of wood waste supply and

cost completed to date. The assessment includes an estimate of the overall quantity of wood

waste available for use as fuel and a sound methodology to project woodfuel prices. It provides

a not only a valuable tool to estimate wood waste amounts and costs, but also to understand the

impact of economic factors on delivered price. The assessment will be of great value in my task

of estimating the overall amounts and price of wood waste in the U.S.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

31

TITLE: The Changing Solid Waste Wood Resource in the United States, 1990-1998(a)

BY: David McKeever(a)

Forest Products Laboratory

USDA Forest Service

Madison, Wisconsin

FOR: BioCycle Journal of Composting & Recycling (a)

DATE: Prepared for publication November 19981

(a): David McKeever with others at the Forest Products Laboratory have completed several reports, papers, articles,

and presentation on wood waste generation, recycling, and disposal in the U.S. The article published in

BioCycle Journal of Composting & Recycling in January 1998 is the latest public presentation of their

research. Collectively, the documents authored (solely or with other co-authors) by David McKeever are

referred to by the title used in the BioCycle article.

SUMMARY

The assessment provides estimates of wood waste generation, recovery or combustion, and

available for recovery (for fuel or other uses) in the U.S. The assessment focus on three sources

of wood waste:

• Municipal solid waste (MSW), including the wood waste components of MSW as well

as woody yard trimmings;

• Construction and demolition (C&D) activities; and

• Primary wood products industry, including bark and wood residues.

The NRBP study focuses on secondary wood products industry residues or wood waste produced

further along in the production. The sources of wood wastes included in this assessment that are

of interest to the NRBP study are MSW and C&D activities.

The author utilizes the most recent MSW data published by Franklin Associates, and thus

represents the most current U.S. EPA information on MSW wood waste. Presented in Table 2-

11 is a summary of the estimated amounts of MSW wood waste generation, recycling, disposal,

and that available for recovery.

The estimates of MSW wood waste do not include pallets that were repaired, refurbished, or

recycled. The author sites the research by Robert Bush, Philip Araman, and Vijay Reddy which

indicate that 5,300,000 million tons of used pallets were repaired or recycled. The quantity of

pallets repaired or recycled are not included in the quantities presented in Table 2-11.

It appears that land clearing debris is not included since this material it is typically not managed

as MSW (and thus is not included in estimates of MSW wood), is not included as a type of

construction wood waste, and is clearly not a demolition wood waste or primary mill residue. It
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TABLE 2-11: MSW Wood Waste Generation, Recycling, Disposal, and Available for

Recovery in 1998.

Amount Percent of Generation

MSW Wood Waste

Generation(a) 11,800,000 tons

Recycling and Composting(a) 600,000 tons 5.1%

Combustion(b) 3,100,000 tons 26.3%

Unacceptable for Recovery(c) 2,700,000 tons 22.9%

Remainder = Available 5,400,000 tons 45.8%

(a): Does not included an estimated 5,300,000 tons of used pallets that were repaired or recycled.

(b): Assumed to be in waste-to-energy facilities, facilities that burn refuse-derived fuel, and incinerators.

(c): Due to commingling, contamination, or other reasons.

also appears secondary wood products industry (“secondary mills”) residues are also not

included. Secondary mill residues would be classified as “industrial process waste” in the U.S.

Environmental Protection Agency’s MSW characterization studies (see the summary of

Characterization of Municipal Solid Waste in The United States: 1997 Update), which are

used by the author to estimate the amount of wood waste in MSW. Industrial process wastes are

not included in the U.S. EPA estimates of MSW.

The estimates of MSW wood waste and yard trimmings generation and recycling are also based

on estimates in the U.S. EPA MSW characterization studies. Yard waste is noted to be the

largest component of MSW, and comprises about 12% of total MSW generation. Presented in

Table 2-12 are the estimated amounts of woody yard trimmings MSW wood waste generation,

recycling, disposal, and that available for recovery. The author assumes that 95% of yard

trimmings is woody, which is based on information presented in Urban Tree Residues: Results

of the First National Inventory. This assumption is consistent with the results presented in

Table 2-5. However, there may be large differences between yard trimmings in MSW and

UTRs. As noted in Characterization of Municipal Solid Waste in The United States: 1997

Update, there is little data on the composition of yard trimming, and yard trimming are assumed

to consist of 50% grass, 25% brush, and 25% leaves. The assumed composition in the 1997

Update suggests yard trimmings contain at most 25% wood as brush.

TABLE 2-12: Woody Yard Trimmings Generation, Recycling, Disposal, and Available for

Recovery in 1998.

Amount Percent of Generation

Woody Yard Trimmings Generation(a) 25,200,000 tons

Recycling and Composting(a) 11,100,000 tons 44.0%

Combustion(b) 3,900,000 tons 15.5%

Unusable(c) 3,400,000 tons 13.5%

Remainder =Available 6,800,000 tons 27.0%

The author notes that construction debris and demolition debris are typically referred to or

combined into a single form of waste, but in reality they are generated by different activities and
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33

have different characteristics. Because of this, the generation, recycling, disposal, and

availability of construction (and the related repair and remodeling) debris should be evaluated

separately from demolition debris.

Estimates of wood waste generated by construction and repair/remodeling of residential and nonresidential buildings is based on construction activities as well as the wood products used in their

construction. The author notes there is much information available regarding these parameters

from the U.S. Department of Commerce, Bureau of Census, Wood Products Council, and others.

David McKeever and others at the USDA Forest Service have also published extensively on

these parameters. The amount of wood waste generation by building-related construction

activities is based on actual case studies. The methodology the author has developed over the

years and uses in this assessment appears similar to that used by Franklin Associates in

Characterization of Building-Related Construction and Demolition Debris in the United

States. A summary of the results for construction wood waste is presented in Table 2-13.

TABLE 2-13: Building-Related Construction Wood Waste Generation and Available for

Recovery in 1998.

GENERATION AVAILABLE FOR RECOVERY

Amount

(tons)

Amount

(tons)

Percent of

Generation

(%)

Residential Buildings

Construction 3,400,000 3,000,000 88.2

Repair/remodeling 4,300,00 2,800,000 65.1

Subtotal 7,700,000 5,800,000 75.3

Non-Residential

Buildings

Construction and

repair/remodeling 1,000,000 900,000 90.0

TOTAL 8,700,000 6,700,000 77.0

Estimates of building-related demolition debris and wood waste are based on a per capita

generation rate of about 1.3 pounds/capita/day derived from quantities estimate in

Characterization of Building-Related Construction and Demolition Debris in the United

States. The amount of demolition debris generated in 1998 was calculated to be 66,000,000

tons based on the 1998 U.S. population, or about a 1.8% increase from that estimated by Franklin

Associates for 1996. The author assumes wood waste comprises 40% of demolition debris, or

about 26,400,000 tons in 1998. The amount of demolition wood waste considered to be

available for recovery is based on information provided by a C&D recycling facility located in

Massachusetts and projections of advances in C&D recovery, separation, and recycling

technologies. Overall, 30% or about 9,000,000 tons of demolition wood waste generated in 1998

is considered available.
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Urban Wood Waste Quantities in the U.S.

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LIMITATIONS OF THIS ASSESSMENT

There are few limitations associated with this assessment and the quantities of MSW wood

waste, woody yard trimming, construction and repair/remodeling, and demolition wood waste.

For construction and repair/remodeling wood waste, the author uses a rigorous methodology that

is similar to that used by Franklin Associates in Characterization of Building-Related

Construction and Demolition Debris in the United States. The estimate by Franklin

Associates is for building-related construction and repair/renovation debris, and not for the wood

waste component within. Thus, it is difficult to compare Franklin Associates’ estimates to David

McKeever’s. However, assuming wood waste comprises 35% of building-related construction

and repair/renovation debris estimated by Franklin Associates, the two estimates appear

relatively close. One limitation of the estimate of construction and repair/renovation wood waste

is the amounts judged to be available for recovery. There is little if any information presented on

how the quantities were derived, and thus it is not possible to verify or evaluate whether the

assumption are reasonable.

This assessment relies of previous research by Franklin Associates and others to estimate the

amount of MSW wood waste, woody yard trimmings, and demolition wood waste, which are

adjusted to reflect 1998 quantities. The methodologies used to adjust data to reflect 1998

quantities appear to be appropriate. However, several of the assumptions regarding wood waste

quantities or availability should be mentioned:

• No explanation is provided regarding the how amount of MSW wood and woody yard

trimmings judged to be unacceptable for recovery was derived, thus it is not possible to

verify or evaluate whether the assumptions used are reasonable.

• The estimate of woody yard trimming assumes that 95% of yard trimmings is wood waste,

which is based on estimates wood waste in UTRs. However, UTRs and yard trimmings are

different materials, and the quantities of wood waste within each will likely differ. It appears

more reasonable and conservative to assume wood waste comprises no more than 25% of

yard trimmings.

• Demolition wood waste is assumed to contain 40% wood waste. The literature often cites

C&D debris (combined together) as containing 25% to 40% wood waste. The six C&D

sorting studies identified in Characterization of Building-Related Construction and

Demolition Debris in the United States indicate C&D debris contains between 14% and

67% wood waste. There is significant variability in the data on wood waste in C&D debris,

and there appears to be little or no information regarding demolition debris only, and thus it

in not possible to evaluate whether 40% accurately reflects actual amounts.
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Urban Wood Waste Quantities in the U.S.

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WHY INCLUDE THIS ASSESSMENT?

This assessment provides an important estimate of construction and repair/remodeling wood

waste. This estimate can be compared to or verify other estimates of construction wood waste

estimates, such as that in Characterization of Building-Related Construction and Demolition

Debris in the United States. The assessment also provides adjustments of MSW wood waste,

woody yard waste, and demolition wood waste to reflect 1998 quantities.

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SECTION III:

ESTIMATE OF NATIONAL WOOD WASTE QUANTITIES AND PRICES

The seven wood waste assessments identified and discussed in Section 2 were included in this

study because they are judged to be the most complete and utilize the most appropriate or

accurate methodologies to estimate national wood waste quantities and/or prices. However,

without further analysis the assessments cannot be used to estimate the quantity and price of

secondary mill residues and urban wood waste available nationally. The reasons for this include:

• None of the assessments include all types of secondary mill residues and urban wood waste;

• All of the assessments include wood waste that is included in other wood waste assessments,

leading to potential for double counting wood waste when results are combined; and

• With the exception of Biomass Residue Supply Curves for the U.S. (Update), and perhaps

Lignocellulosic Feedstock Resource Assessment, none of the assessments include an

analysis of the prices residues and wood waste will be available at.

The information and data presented in each assessment as well as the assumptions used were

reviewed and analyzed, and estimates of national quantities of secondary mill residues and urban

wood wastes were developed. The methodology used included developing a matrix table which

tracked the various steps used in the review and analysis, as well as obtaining additional

information on wood waste that were not included in the seven assessments.

METHODOLOGY USED TO DEVELOP ESTIMATES OF QUANTITIES AND PRICES

The methodology used involved various steps as well as developing a matrix table to track and

document the results of each step. The matrix table is presented in Appendix B. The steps are

described below:

Identify The Types Of Wood Waste Included In Each Assessment

The seven assessments included a wide range of wood residues or wastes as well as other types

of biomass feedstocks. In this preliminary step, the types of secondary mill residues or urban

wood waste included in each assessment were identified.
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Urban Wood Waste Quantities in the U.S.

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Further Interpret The Types Of Wood Waste

Many of the types of wood residue or waste included in an assessment are actually a combination

of many different wood wastes. For instance, “MSW wood waste” may be comprised of

household wood waste, commercial wood waste, institutional wood waste, pallets, and yard

waste. Based on the review of each assessment and the assumptions used, the types of wood

residue or waste were further delineated to identify the specific types of wood that are or are not

included.

Identify The Types Of Wood Waste That Are Included In Other Assessments

A key aspect of developing a defendable estimate of biomass quantities is demonstration that

most, if not all types of appropriated biomass are included, and that “double counting” does not

occur. Double counting is counting more than once a specific type of biomass. Within each

assessment, all wood wastes were reviewed to determine which assessments also included the

wood waste.

Choose Which Assessment To Use For Each Type Of Wood Wastes

This is a difficult step, and involves determining which assessment(s) provides the most

complete or comprehensive assessment for a particular type of wood residue or waste. In some

cases it is obvious which assessment’s methodology is best or which assessment is the most

complete, in other cases it is less so. For each type of wood residue or waste, the quantity

estimated by the assessment judged to be the most complete, comprehensive, and/or current was

used in the estimate of the national quantity.

Estimate National Generation

Generation, as defined in this study, is the amount of wood waste produced by all generators

prior to any reuse, recycling, disposal, or other diversion. Mathematically, generation should

equal the sum of reuse, recycling, and discards.

The estimate of national wood waste generation is the sum of that estimated for all individual

types of secondary mill residues and urban wood waste. It is important to note that generation is

not the amount potentially available for fuel or other uses. Generation includes that which is

available for fuel as well as that not available due to reuse, higher value markets, contamination,

commingling, and other factors.

Estimate Amounts Potentially Available For Fuel

This is a tricky step because it involves assumptions, and different assumptions will lead to

different results. For the purpose of this study, two assumptions were made. The first is to
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Urban Wood Waste Quantities in the U.S.

39

assume commingled and/or contaminated wood waste is not available for use as fuel.

Commingling and/or contamination are issues with wood waste in construction and demolition

(C&D) debris as well as wood waste in municipal solid waste (MSW). Contamination refers to

the presence (or potential presence) of variable amounts of non-wood materials that negatively

impact fuel quality, air emissions, and/or ash emissions. Contamination does not include sourceseparated treated wood waste, which is wood containing non-wood materials such as adhesives.

For instance, residues from the manufacture of plywood (or other wood products containing

adhesives) are considered available for fuel since they can be used as fuel in certain applications.

The second is to assume wood residues or wastes currently used by "high-value" markets such as

pulp, sawtimber, or engineered wood products manufacturing are not available for use as fuel.

It is beyond the scope of this study to complete a analysis of the amount of commingled and/or

contaminated wood is present in secondary mill residues or urban wood waste as well as how

much of these residues or wastes are utilized by high-value markets. Instead, the research

completed by others was relied on. Specifically:

• For secondary mill residues, the material is assumed to be source separated (and not

commingled or contaminated) since it is generated in an industrial/manufacturing setting

with relatively high potential for source separation. This assumption likely results in some

overestimating the amount of residues potentially available since some secondary mills will

generate residues that cannot be used as fuel, even if source-separated. However, this

amount is judged to be relatively small. And when combined with the concern that the

methodology used to estimate secondary mill residues tends to underestimate residue

generation, this assumption should not lead to significant overestimation of available

secondary mill residues. The amount of secondary mill residues used in high value markets

is estimated based on estimates of “captive markets” presented in Lignocellulosic Feedstock

Resource Assessment. Although not specifically defined, the term “captive markets”

implies it is those markets that pay a high enough price for wood residues that there is little

potential the residues they receive will be diverted to lower value markets such as fuel.

• For urban tree residues (UTRs), the material is assumed not to be commingled or

contaminated since it is comprised solely of tree and other woody biomass residues. As

shown in Table 2-7, the results of the survey used in the study Urban Tree Residues:

Results of the First National Inventory indicated that 88% of the material is given away,

sold or used as fuel, used in low-value markets (such as compost or mulch), or is disposed,.

This indicates 88% the material is potentially available as fuel. This estimate is likely

conservative (i.e. the actual percentage is higher), since at least some of the 12% assumed to

not be available (due to being used in high value markets) is likely actually used by low

value markets, and thus actually would be available.

• For C&D and MSW wood waste, the amount commingled, contaminated, and

reused/recycled is based on research completed by David McKeever and presented in

BioCycle Journal of Composting & Recycling articles as well as personal communications.

For wood waste generated by construction and renovation of buildings, of the 8,700,000

tons/year generated, an estimated 2,100,000 tons/year, or 24% are either being recovered or
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Urban Wood Waste Quantities in the U.S.

40

are not usable. Of this amount, it is not possible to determine how much is not available due

to commingling or contamination, or how much is recovered. Thus, a conservative (i.e.

underestimates the amount potentially available for fuel) assumption was made that 76%

(100%-24%=76%) is available for fuel. For demolition wood waste, David McKeever

assumes an initial recovery rate of 30%, which is in part based on the performance of a

recycling facility located in Massachusetts that accepts and processes demolition wood

waste. For MSW wood, David McKeever estimates MSW wood waste generation at

11,800,000 tons/year. Of this amount, 2,700,000 tons/year, or about 23% are unacceptable

for recovery because of contamination, commingling, or other reasons. This implies that

about 77% (100%-23%=77%) are potentially available for recovery and use as fuel.

The amount of a wood residue or waste generated less the amount commingled, contaminated, or

used in high value markets is the amount potentially available for fuel. High value markets for

wood residues or wastes, such as pulp, sawtimber, engineered wood products manufacturing

often pay $23/green ton and upwards for wood delivered to the to the plant. The price paid by

these markets can be highly variable depending on the economy, location, season, competing

resources, transportation distances, and other factors. However, the results of many wood

residue or waste assessments completed across the U.S. indicate $23/ton is representative of the

overall price paid by high value markets.

Estimate The Amount Available At Greater Than $20/ton Delivered

A simplifying assumption is made that the amount of wood residues and waste available at a

price of $20/ton or greater is assumed to be the amount potentially available. This assumption is

made based on the overall price high value markets pay for wood feedstocks as well as the

methodology used to estimate the amount potentially available. Since the amount potentially

available assumes quantities used by high value markets is not available, it is reasonable to

assume that all other available quantities are available up to (and above) the price high value

markets pay.

Estimate The Amount Available At $10 and $20/ton Delivered

To estimate the quantity of wood residues and waste potentially available at or up to specified

prices, the methodology developed by Antares Group, Inc. and presented in Urban Wood Waste

Resource Assessment was adopted and modified slightly. As described in the previous section,

this methodology involves determining the “delivered residue cost” (DRC), which is based on

wood residue or waste collection and processing costs, transportation costs, and disposal (in

landfills). The DRC is estimated as follows:
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Urban Wood Waste Quantities in the U.S.

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DRC = RPC + RTC - 1⁄2(LFT)

Where:

RPC = Average collection and processing cost, which vary for the 7 types of wood wastes.

RTC = Transportation cost, which vary depending on one of four assumed transportation distances and state

specific transportation cost index.

LFT = Average cost to disposed solid waste in landfills (i.e. “tipping fee”), which vary depending on the state.

The methodology used in Urban Wood Waste Resource Assessment includes determining

DRC based on assumed processing costs and state-specific data on the transportation cost index,

state size, and average tipping fee. Within each state, the quantity of a wood residue or waste

type generated (or available) is “allocated” to one of four transportation distances based on area.

The transportation distances are 25 miles, 50 miles, 75 miles, and 100 miles, and the

corresponding allocation is 6%, 19%, 31%, and 44% respectively.

For this study, it is desirable to know what amounts or percent of wood residue or waste that is

available at or up to a specified delivered price. To do this, the equation used to calculate DRC

was used to estimate the national average DRC for each type of wood residue or waste for

transportation distances of 25, 50, 75, and 100 miles. The calculated national average DRC was

then graphed against the corresponding allocation expressed as a cumulative. This graph allows

estimation of the percent of a mill residue or urban wood waste available at specified national

average DRC. The allocation is expressed as a cumulative percent so the graph plots DRC (on

the “y” axis) against 0% to100% of available wood residue or waste. A summary of the

calculated DRC and graph of DRC versus cumulative percent available is presented in Appendix

C.

The residue collection and processing costs (RPC) estimated by Antares Group were used (the

costs are presented in Table 2-8), as was a national freight cost of 24.11¢/mile. The RPC for

secondary mill residues and used pallets were not specifically estimated in Urban Wood Waste

Resource Assessment, but it is reasonable to assume these cost are also $12/ton, or the same as

for construction wood waste, demolition wood waste, yard waste, and other wood waste. This is

because these residues are similar in nature, and thus the collection and processing costs should

also be similar. In addition, the “other wood waste” category identified and used in Urban

Wood Waste Resource Assessment likely includes some secondary mill residues and used

pallets, indicating it is reasonable to assume the collection and processing cost for the three types

of wood wastes is the same.

The average national landfill tipping fee was estimated based on information presented in the

article “The State of Garbage in America: 11th Annual BioCycle Nationwide Survey” published

in BioCycle Journal of Composting & Recycling in April 1999. The BioCycle article contains

information on solid waste generation, landfill tipping fee, and incineration tipping fee for each

state. Based on the BioCycle data, the average weighted landfill and incinerator tipping fee for

the U.S. was calculated to be $24.50/ton. The data used in and the results of the spreadsheet

software used to calculate the average weighted tipping fee is presented in Appendix D.
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Urban Wood Waste Quantities in the U.S.

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Analysis of the graph of calculated DRC versus percent of wood residue or waste was plotted

indicates that about 22% of secondary mill residues and urban wood waste are available

(including delivery) at a price of up to $10/green ton, and 62% or available at a price of up to

$20/green ton. In addition, 100% or all secondary mill residues and urban wood waste would be

available at a price of about 23.86/green ton. This amount is extremely close to the anticipated

price paid by high value markets for wood residues and wastes.

Identify Types Of Wood Wastes Not Included

Also important in developing a defendable estimate of national quantities is identifying what key

or important types of wood residues or waste are not included. Since the focus of this study is on

wood residues and waste that are potentially available for fuel (as well as other uses), the focus

of this step is to identify key types of waste wood fuel that are not included.

Based on the review of the seven assessments, four types of wood waste are not included or

incomplete amounts are included in the seven assessments. These are:

• Used pallets

• Landclearing wood waste;

• Used wood railroad ties; and

• Used wood utility poles.

Presented below is a brief description of the four types of wood waste as well as readily available

information on quantities.

Used Pallets

Used pallets typically contain only clean, untreated wood and metallic fasteners. A small portion

of used pallets may be contaminated with paint or other surface coatings, non-wood materials

(such as adhesives or preservatives), or materials that spilled on to the pallets. The majority, if

not all metallic fasteners can be removed using magnetic or other separation technologies. In

general, ground or chipped pallets consist of only clean, untreated wood and an excellent source

of woodfuel.

The types and amounts of used pallets contained in the various wood waste assessments is

neither consistent or clear. For instance, the quantity of used pallet generation reported in

Characterization of Municipal Solid Waste in the United States, 1997 Update does not

include pallets that are repaired or refurbished, since this is considered to be “reuse”, and waste

materials that are reused are not included in estimates of MSW generation. Similarly, used

pallets that are repaired, refurbished, or recycled are not included is estimates of MSW wood

waste reported in The Changing Solid Waste Wood Resource in the United States, 1990-

1998. Presented in Table 3-1 is a summary of used pallet generation, reuse/recycling, and
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Urban Wood Waste Quantities in the U.S.

43

disposal which is intended to provide a more clear picture of used pallet quantities as well as that

potentially available for fuel.

According to Characterization of Municipal Solid Waste in the United States, 1997 Update,

nearly 200,000,000 pallets were repaired or refurbished in 1996 (but, as noted above, this

quantity is not included in MSW quantities). Assuming pallets have an average weight of 55

pounds, this indicates that over 5,500,000 pallets were repaired or refurbished in 1996. The

average pallet weight is adopted from pallet generation data from Robert Bush, Philip Araman,

and Vijay Reddy. According to data compiled by Robert Bush et al, over 223,000,000 used

pallets, or about 6,140,000 tons were taken to MSW or C&D landfills in 1996. Of this amount,

17%, or 1,044,000 tons were recovered, mostly for use in low value end uses or products. The

remaining 5,096,000 million tons were disposed in either MSW or C&D landfills.

The repair or refurbishing of used pallets is a high value use, and these pallets will not be

available for fuel or other lower value uses. However, the 6,140,000 tons of used pallets taken to

landfills can be assumed to be available. This is because this amount is either used by low value

markets (that fuel markets could compete with), or is disposed. Contamination and

commingling of used pallets with other wastes will likely limit the actual amount that is

available. However, since used pallets tend to be clean, contamination is likely a minor issue.

Commingling may have a bigger impact on availability than contamination. However, pallets to

be taken to landfills are often already separated, or are easily separated at the generator, by

haulers, at landfills, or at transfer stations. Thus it can be assumed that commingling is also a

relatively minor issue. It is important to note that assuming contamination and commingling are

minor issues (and all used pallets taken to landfills are available) will result in minor

overestimation of the amount actually available.

TABLE 3-1: Estimates of Used Pallet Generation, Reuse/Recycling, and Disposal

Reuse/Recycling

Pallet Management

Generation(a)

(tons/yr)

High Value

Markets(b)

(tons/yr)

Low Value

Markets(c)

(tons/yr)

Disposal(b)

(tons/yr)

Taken to Landfills 6,140,000 0 1,044,000 5,096,000

Repaired/Refurbished 5,500,000 5,500,000 0 0

TOTAL 11,640,000 5,500,000 1,044,000 5,096,000

(a): Generation includes used pallets that have served their initial function and have been recovered for reuse, repair,

or refurbishing.

(b): Pallet repair and refurbishing is considered to be a high value market, and the amount of used pallets repaired or

refurbished is assumed not to be available for fuel.

(c): Used pallets recycled via low value markets and disposed are considered available for fuel.

Land clearing Wood Waste

Wood waste generated by clearing land of trees and stumps prior to construction of buildings,

other structures, or roads. Land clearing wood consists primarily, if not solely of clean,
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Urban Wood Waste Quantities in the U.S.

44

untreated wood. Since land clearing wood is similar to pulpwood and sawtimber harvested from

the forest, it is sold to these markets when possible. Land clearing wood is also chipped for fuel,

mulch, or other markets, or may be sold as cordwood. Because land clearing wood is generated

as part of construction activities, it is often identified as a type of C&D debris or wood waste. In

Urban Wood Waste Resource Assessment, land clearing wood is specifically identified as a

component of C&D wood waste. However, incomplete information on the amount of land

clearing wood generated was obtained, as the author notes, “It was not possible to obtain even

rough estimates of the amounts of wood generated by construction contractors, demolition

contractors, and land clearing companies.” Information was obtained on the amounts of C&D

reused or recycled as well as disposed, but it is not possible to estimate how much is C&D wood

and how much is land clearing wood. In Characterization of Building-Related Construction

and Demolition Debris in the U.S., land clearing debris is identified as a component of C&D

debris, but is specifically not included in the types of C&D debris included in the assessment.

Used Railroad Ties

Used railroad ties (ties) are generated by the repair, refurbishing, or removal of railroad tracks.

Ties can be made of various materials such as concrete or plastic, but the majority is creosotetreated wood. Used creosote-treated wood ties have successfully been used as fuel in various

applications, including wood-fired power plants and co-firing at coal-fired utility power plants.

According to the Railway Tie Association (RTA), approximately 12,500,000 ties are used in

Class 1 railroads, with an unknown amount used in Class II and other railroads. The majority of

ties used in Class 1 railroads are due to track maintenance and upgrades, as opposed to new track

construction. This indicates that a corresponding amount of ties are replaced annually. The

average weight of a tie is about 250 pounds, and the overall weight of used creosote-treated ties

generated annually is calculated to be 1,688,000 tons. Anecdotic information on tie generation

for non-Class I railways suggest the quantities will likely greatly surpass that of Class I railways,

but this information cannot be verified. Information on used tie collection, processing, and

transportation is not available, and thus it is not possible to estimate the amounts available.

Used utility poles

Used utility poles are generated by the repair or replacement of utility poles. Utility poles can be

made of various materials such as steel or concrete, but the majority is treated wood. Wood

utility poles are commonly treated with creosote, pentachlorophenol (penta), or chromated

copper arsenate (CCA), or other preservatives. Similar to creosote-treated railway ties,

creosote-treated utility poles have been successfully used as fuel in various applications. At least

one large wood-fired power plant was permitted to burn up to 50% penta-treated wood.

However, there are air emission issues surrounding penta, and it appears penta use as a

preservative for utility poles may be declining. CCA-treated wood appears to have limited, if

any use as woodfuel due to the presence of chromium, copper, and arsenic. One issue

surrounding utility poles is “ground treatments” which are preservatives, insecticides, or other

chemicals applied to the utility pole at or near the ground level. Ground treatments are used to

increase the in-ground life of the pole. The issue is that ground treatments can contaminate poles
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

45

that would otherwise be viable woodfuels. An example is the use of the preservative CCA as a

ground treatment for creosote-treated poles. Information on used utility pole generation,

collection, processing, transportation cost, recycling, and disposal is limited, if available at all,

and it is not possible to estimate quantities.

RESULTS

Presented in Table 3-2 are the results of the national estimate of secondary mill residues and

urban wood waste quantities and prices. The amount generated is estimated to be over

136,000,000 tons/year. Generation refers to production of wood residues or wastes prior to any

reuse, recycling, disposal, or other management except internal reuse or cycling. Of this

amount, over 87,000,000 tons/yr, or 64% of that generated, is potentially available for fuel or

other lower value uses. At a price of up to $10/ton, it is estimated that just under 20,000,000

tons/yr are available, and at a price of up to $20, an estimated 54,000,000 tons are available. It is

important to note the overall generation and available quantities are minimums, the actual

amount likely exceed that report. This is because reliable data on several types of wood waste

(with potential to be used as woodfuel) is not currently available, and could not be included in

the estimates

The results include some interesting results, including

• At a delivered price of $0 - $10/ton, woodfuel is considered to be competitive with fossil

fuels, in particular with coal. This analysis indicates that just under 20,000,000 tons/yr are

available at a price of $10/ton.

• At about 45,000,000 tons/year, UTRs represents the largest single source of available wood

waste. The amount of UTRs available exceeds the other types of wood waste by at least a

factor of 4.

• Although demolition wood waste is generation in large quantities, issues surrounding

commingling, contamination, and separation greatly affect its potential availability. The

opposite is true of construction wood waste.

• Anecdotic information indicates that railroad ties and site clearing wood waste may represent

additional large sources of potentially available wood. Research into the quantities and

availability of these wood wastes should be conducted so a more complete picture of the

wood waste availability is obtained.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

46

TABLE 3-2: National Wood Waste Quantities and Prices

WOOD WASTE

TOTOL

GENERATION

(Tons/year)

AVAILABLE

@ up to $10/ton

(Tons/year)

AVAILABLE

@ up to $20/ton

(Tons/year)

AVAILABLE

@ above $20(c)

(Tons/year)

Secondary mill 15,644,000 1,342,000 3,783,000 6,101,000

Construction 16,726,000 2,796,000 7,882,000 12,712,000

Demolition 26,400,000 1,742,000 4,910,000 7,920,000

MSW(a) 11,800,000 1,999,000 5,633,000 9,086,000

Yard trimmings 6,300,000 1,199,000 3,379,000 5,450,000

Urban tree residues 51,455,000 9,962,000 28,074,000 45,280,000

Used pallets(b) 6,544,000 230,000 647,000 1,044,000

Railroad ties 1,688,000 n/a n/a n/a

Land clearing n/a n/a n/a n/a

Used utility poles n/a n/a n/a n/a

TOTAL <136,557,000 <19,270,000 <54,308,000 <87,593,000

(a): Includes used pallets that are disposed in landfills.

(b): Includes used pallets that are repaired, refurbished, or recycled. Used pallets are disposed in landfills are

included as MSW wood waste.

(c): The methodology used to estimate quantities and prices equates wood waste available at $20 and above with

that that potentially available for fuel. Wood waste potentially available as fuel is defined as the quantity

generated less that used by high value markets and that which is commingled, unseparatable, or contaminated.

n/a: Data not available.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

A-1

Appendix A - BIBLIOGRAPHY

Antares Group Inc. Biomass Residue Supply Curves for the United States (Update).

Prepared for the U.S. Dept. of Energy’s Biomass Power Program and the National Renewable

Energy Laboratory. Washington, D.C. and Golden, CO. June 16, 1999.

Appel Consultants, Inc. Urban Wood Waste Resource Assessment. Prepared for the National

Renewable Energy Laboratory. Golden, CO. NREL/SR-580-25918. November 1998.

Araman, Philip, Project Leader. USDA Forest Service, Southern Research Station. Blacksburg,

VA. Personal Communication. August 10, 1999.

Araman, Philip A., Robert J. Bush, E. Bradley Hager, and A.L. Hammett. “Landfill Potential

Source of Cores”. Published in Pallet Enterprise. Richmond, VA. February 1999.

Bush, Robert J., Philip A. Araman, and Vijay S. Reddy. “Construction and Demolition Landfills

and Wood Pallets - What’s Happening in the United States”. Published in Pallet Enterprise.

Richmond, VA. March 1997.

Chapman, Mary, Forster - Economic Action. USDA Forest Service, State and Private Forestry,

Northeastern Area. Durham, NH. Personal Communication. August 13, 1999.

Comer, Kevin. Antares Group Inc. Landover, MD. Personal Communications. July, August,

and September 1999.

C.T. Donovan Associates, Inc. Recycling Construction and Demolition Waste in Rhode

Island. Prepared for the Rhode Island Governor’s Office of Housing, Energy, and

Intergovernmental Relations. Providence, RI. December 1992.

C.T. Donovan Associates, Inc. Recycling Construction and Demolition Waste in Vermont.

Prepared for the Vermont Agency of Natural Resources, Recycling and Resource

Conservation Section. Waterbury, Vermont. December 1990.

Gauntt, James, Executive Director. Railway Tie Association. Fayetteville, GA. Personal

Communications. December 10 and 20, 1999.

Glen, Jim, Senior Editor. BioCycle Journal of Composting & Recycling. Emmaus, PA.

Personal Communication. October 10, 1999.

Glenn, Jim. “The State of Garbage in America: 11th Annual BioCycle Nationwide Survey”.

Published in BioCycle Journal of Composting & Recycling. Emmaus, PA. April 1998.

Lee, Eugene. U.S. Environmental Protection Agency, Office of Solid Waste. Washington, D.C.

Personal Communication. August 6, 1999.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

A-2

McKeever, David, Research Forester. USDA Forest Service, Forest Products Laboratory.

Madison, WI. Personal Communications. July, October, November, and December 1999.

McKeever, David. “The Changing Solid Waste Wood Resource in the United States, 1990-

1998”. Prepared for publication in BioCycle Journal of Composting & Recycling.

Emmaus, PA. November 1999.

McKeever, David. “Wood Residual Quantities in the United States”. Published in BioCycle

Journal of Composting & Recycling. Emmaus, PA. January 1998.

NEOS Corporation. Lignocellulosic Feedstock Resource Assessment. Prepared for the

National Renewable Energy Laboratory. Golden, CO. NREL/TP-580-24189. September

1998

NEOS Corporation. Urban Tree Residues: Results of the First National Inventory.

Prepared for the International Society of Arboriculture Research Trust, Allegheny Power

Service Corporation, and National Arborist Foundation. September 1994.

Perhac, Ralph. University of Tennessee. Personal Communication. July 8, 1999.

Rooney, Tim. McNeil Technologies, Inc. Golden, CO. Personal Communications. October

and November 1999.

U.S. Environmental Protection Agency. Characterization of Building-Related Construction

and Demolition Debris in the United States. EPA530-R-98-010. Washington, D.C. June

1998. Prepared by Franklin Associates, Prairie Village, KS.

U.S. Environmental Protection Agency. Characterization of Municipal Solid Waste in the

United States. EPA530-R-98-007. Washington, D.C. May 1998. Prepared by Franklin

Associates, Prairie Village, KS.

Walsh, Marie, Ph.D., Agricultural Economist. Oak Ridge National Laboratory. Oak Ridge, TN.

Personal Communication. September 10, 1999.

Wiltsee, George. Appel Consultants, Inc. Valencia, CA. Personal Communication. September

13, 1999.

Wiselogel, Art, Senior Scientist. National Renewable Energy Laboratory. Golden, CO.

Personal Communication. September 10, 1999.

Wright, Lynn, Deputy Program Manager, Bioenergy Feedstock Development Program. Oak

Ridge National Laboratory. Oak Ridge, TN. Personal Communication. September 10, 1999.

Wood, John. Franklin Associates. Prairie Village, KS. Personal Communication. December

14, 1999.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

B-1

Appendix B - Matrix Table
ASSESSMENT 

NUMBER

WOOD WASTE ASSESSMENT

Author, Date of Report

WASTE INCLUDED

(as identified by the 

assessment's author)

WASTE INCLUDED

(as further intrepreted

by J.E. Fehrs, P.E.)

ANNUAL WOOD WASTE 

GENERATION 

IDENTIFIED IN 

ASSESSMENT UNITS

Building-related construction and 

repair/renovation debris

 Debris from construction, remodeling, and repair of residential and non-residential buildings.

 Does not include debris from road & bridge construction or repair.

 Does not include landclearing debris.

 Construction and renovation debris comprise 8% and 44% of C&D debris respectively.

 Assessment 1 includes the results of 6 building-related C&D waste composition studies, which 

indicate wood waste comprises 14 to 65% of C&D debris.

 C/D debris typically contains between 15 and 40% wood waste. 9,901,000 to 47,382,000 Green tons/yr

1

Characterization of BuildingRelated Construction and 

Demolition Debris in the U.S.

Franklin Associates, Ltd, 1998

Building-related demolition 

debris

 Debris from demolition of residential and non-residential buildings.

 Does not include debris from road & bridge demolition.

 Demolition debris comprise 48% of C&D debris respectively.

 Assessment 1 includes the results of 6 building-related C&D waste composition studies, which 

indicate wood waste comprises 14 to 65% of C&D debris. 9,792,000 to 26,112,000 Green tons/yr

Wood in MSW

 Household wood waste.

 Commercial wood waste.

 Institutional wood waste.

 Recycled or landfilled pallets and shipping containers.

 Industrial wood waste.

 Does not include reused pallets 10, 840,000 Green tons/yr

2

Characterization of Municipal 

Solid Waste in the U.S., 1997 

Update

Franklin Associates, Ltd, 1988 Yard trimmings

 Leaves, grass, and tree and brush trimmings

 Residential, institutional, and commercial sources

 Estimated to contain no more that 25% wood (as tree trimmings) <7,000,000 Green tons/yr

Secondary mills residues 12,515,000 Dry tons/yr

3

Lignocellulosic Feedstock 

Resource Assessment

NEOS 1998 Urban tree residues (UTRs) Information on UTR is from Assessment 4. 37,953,000 Dry tons/yr

4

Urban Tree Residues: Results 

of the First National Inventory

NEOS 1994

Urban tree residues (UTRs) or 

"Green" materials generated by 

urban forestry related businesses

 Solid wood residues generated by tree maintenance and landscaping activities on municipal and 

(residential, commercial, industrial, and institutional) private property.

Believed to include storm-related UTR.

 Does not include non-wood UTRs such as grass and leaves.

 Does not include residues from landclearing activities.

 Does not include residues from orchards. 194,508,000 Cubic yards/yr

Wood waste in MSW

 Household wood waste.

 Commercial wood waste.

 Institutional wood waste.

 Yard waste.

 Municipal tree waste.

 Utility tree waste. 39,000,000 Green tons/yr

Industrial wood waste

 Pallets

 Industrial wood waste

 Primary mill residues

 Secondary mill residues 8,000,000 Green tons/yr

5

Urban Wood Waste Resoruce 

Assessment

Appel Consultants, Inc., 1998 C/D wood waste

 Building-related C&D wood waste

 Bridge &road-related C&D wood waste

 Landclearing wood waste 17,000,000 Green tons/yr

Construction wood waste  Same as Assessment 7 6,238,000 Green tons/yr

Demolition wood waste  Wood waste from demolition of buildings. 7,864,000 Green tons/yr

Woody yard trimmings

 Same as that for Assessment 2

 Assumes 95% of yard trimmings is wood 10,123,000 Green tons/yr

6

Biomass Residue Sipply 

Curves for the U.S. (Update)

Antares Group Inc., 1999 Other wood waste

 Similar to MSW wood waste.

 Pallets and shipping containers.

 Industrial wood waste.

 Some, but likely not all secondary mill residues. 6,759,000 Green tons/yr

Wood in MSW

 Same as that for Assessment 2.

 Includes used pallets discarded in landfills.

 Does not in include used pallets that are repaired, refurbished, or recycled. 11,800,000 Green tons/yr

Woody Yard Trimmings

 Same as that for Assessment 2

 Assumes 95% of yard trimmings is wood 25,200,000 Green tons/yr

Construction wood waste

 New residential and non-residential building construction wood waste

 Residential and non-residential building repair and remodeling wood waste

 Does not included road & bridge construction wood waste

 Does not include landclearing wood 8,700,000 Green tons/yr

7

The Changing Solid Waste 

Wood Resource in the U.S., 

1990-1998

David McKeever, 1999 Demolition wood waste  Same as that for Assessment 1 26,400,000 Green tons/yr

8 Railroad ties  Used railroad ties 12,500,000 Ties

9 Other wood waste Used pallets  Repaired, refurbished, or recycled used pallets not inlcuded in MSW wood waste. 6,544,000 Green tons/yr

Page 1 of 5
ASSESSMENT 

NUMBER

WOOD WASTE ASSESSMENT

Author, Date of Report

1

Characterization of BuildingRelated Construction and 

Demolition Debris in the U.S.

Franklin Associates, Ltd, 1998

2

Characterization of Municipal 

Solid Waste in the U.S., 1997 

Update

Franklin Associates, Ltd, 1988

3

Lignocellulosic Feedstock 

Resource Assessment

NEOS 1998

4

Urban Tree Residues: Results 

of the First National Inventory

NEOS 1994

5

Urban Wood Waste Resoruce 

Assessment

Appel Consultants, Inc., 1998

6

Biomass Residue Sipply 

Curves for the U.S. (Update)

Antares Group Inc., 1999

7

The Changing Solid Waste 

Wood Resource in the U.S., 

1990-1998

David McKeever, 1999

8

9 Other wood waste

Year

IS OF WOOD WASTE 

INCLUDED IN OTHER 

ASSESSMENTS?

AMOUNT TO INCLUDE IN 

ESTIMATE OF NATIONAL 

WOOD WASTE GENERATION

(Green tons/yr)

1996 5,6,7 12,376,000

1996 5,6,7 0

1996 5,6,7 0

1996 3,4,5,6,7 0

1996 5 15,644,000

1996 2,4,5,6,7 0

1994 2,3,5,67 51,455,000

1997/1998 2,3,4,6,7 0

1997/1998 3,7 0

1997/1998 1,6,7 0

None 1,5,7 0

None 1,5,7 0

None 2,3,4,5,7 0

None 2,5,7 0

1998 2,3,4,5,6 11,800,000

1998 2,3,4,5,6 6,300,000

1998 1,5,6 4,350,000

1998 1,5,6 26,400,000

1999 1,688,000

1995 6,544,000

TOTAL =

136,557,000

Page 2 of 5
ASSESSMENT 

NUMBER

WOOD WASTE ASSESSMENT

Author, Date of Report

1

Characterization of BuildingRelated Construction and 

Demolition Debris in the U.S.

Franklin Associates, Ltd, 1998

2

Characterization of Municipal 

Solid Waste in the U.S., 1997 

Update

Franklin Associates, Ltd, 1988

3

Lignocellulosic Feedstock 

Resource Assessment

NEOS 1998

4

Urban Tree Residues: Results 

of the First National Inventory

NEOS 1994

5

Urban Wood Waste Resoruce 

Assessment

Appel Consultants, Inc., 1998

6

Biomass Residue Sipply 

Curves for the U.S. (Update)

Antares Group Inc., 1999

7

The Changing Solid Waste 

Wood Resource in the U.S., 

1990-1998

David McKeever, 1999

8

9 Other wood waste

COMMENTS REGARDING GENERATION

AMOUNT POTENTIALLY 

AVAILABLE OF$20 OR 

GREATER

Used similar methodology as that used in Assessment 7 to estimate building-related construction and renovation debris, but differences in 

data intrepretation and use resulted in differences in wood waste estimates.

Assessment 1 includes the results of 6 building-related C&D waste composition studies, which indicate wood waste comprises 14 to 65% of 

C&D debris. An overall wood waste composition of 35% is assumed.

Assume building-related construction and renovation wood waste generation is the average of that estimated in Assessment 1 and 7 (include 

1/2 of generation estimated in Assessment 1). 9,406,000

Use demolition wood waste estimates from Assessment 7 due to being adjusted to reflect 1998 quantities.

Believed to be the most comprehensive data on wood waste in MSW.

Use estimates of MSW wood waste in Assessment 7 due to being adjusted to 1998. 

According to Assessment 2, contains at most 25% wood waste.

It is likely that some UTRs generated by "urban forestry related" businesses estimated in Assessment 4 are also included in yard trimming 

possible leading to double counting. 

 Believed to be the most comprehensive, if not the only national data on secondary mill residues

 Likely underestimates secondary mill residue quantities

 Assumes secondary mill residues have a moisture content of 20% 6,101,000

This estimate is based on UTR data from Assessment 4.

Uses slightly different assumptions for calculating green tons available compared to that done for Assessment 4.

Use estimates of UTR from 4. 

 Converted to green tons/yr based on densities presented in Assessment 3

 Very complete estimate of UTRs

 Uses a similar methodology to estimate national availability of UTRs as Assessment 3, but different assumptions have lead to differences 

in estimates of the quantity potentially available

45,280,000

 Estimate is for urban areas of U.S., and does not include wood waste from rural areas

 Residential, commercial, and institutional wood waste are included in Assessment 2

 Yard waste is included in Assessment 2, but is assumed to not include wood

 Municipal and utility tree waste are included in Assessment 4.

Pallets and shipping containers are included in Assessment 2.

Primary mill residues are not part of this study.

Secondary mill residues are included in Assessment 3.

It is likely minimal quantities of other industrial wood wastes are included as industrial wood waste.

Estimate is for urban areas of U.S., and does not include C/D wood waste from rural areas

The quantity of C&D wood waste generated is incomplete.

Construction and renovation wood waste is included in Assessments 1 & 7.

Demolition wood waste is included in Assessment 7.

Construction and renovation wood waste is included in Assessment 1 & 7.

Demolition wood waste is included in Assessment 7

The amount of yard trimmings assumed to be woody (95%) is judged to be too high.

Likely contains some yard waste generated by "urban forestry related" businesses, which is estimated in Assessment 4.

Woody yard trimmings are included in yard waste in Assessment 7.

 MSW wood waste is included in Assessment 7.

 Industrial wood waste is included in Assessment 5.

 May be small amount of double counting secondary wood waste with Assessment 3.

Adjusts Franklin Associates MSW wood waste data to 1998 9,086,000

Adjusts Franklin Associates yard trimmings data to 1998

The amount of yard waste that is wood assumed in Assessment 7 (95%) is judged to be too high.

Likely contains some yard waste generated by "urban forestry related" businesses estimated in Assessment 4.

Assume yard waste consists of 25% non-UTR wood waste. 5,450,000

Used similar methodology as that used in Assessment 1, but differences in data intrepretation and use resulted in differences in wood waste 

estimates.

Assume building-related construction and renovation wood waste generation is the average of that estimated in Assessment 1 and 7 (include 

1/2 of generation estimated in Assessment 7). 3,306,000

Used estimates of demolition debris from Assessment 2 and adjustes data to 1998 7,920,000 

Ties weight approximately 250 pounds/ea.

Includes only used pallets that are repaired, refurbished, or recycled.

Pallets that are disposed are included in MSW wood waste. 1044000

TOTAL =

87,593,000

Page 3 of 5
ASSESSMENT 

NUMBER

WOOD WASTE ASSESSMENT

Author, Date of Report

1

Characterization of BuildingRelated Construction and 

Demolition Debris in the U.S.

Franklin Associates, Ltd, 1998

2

Characterization of Municipal 

Solid Waste in the U.S., 1997 

Update

Franklin Associates, Ltd, 1988

3

Lignocellulosic Feedstock 

Resource Assessment

NEOS 1998

4

Urban Tree Residues: Results 

of the First National Inventory

NEOS 1994

5

Urban Wood Waste Resoruce 

Assessment

Appel Consultants, Inc., 1998

6

Biomass Residue Sipply 

Curves for the U.S. (Update)

Antares Group Inc., 1999

7

The Changing Solid Waste 

Wood Resource in the U.S., 

1990-1998

David McKeever, 1999

8

9 Other wood waste

COMMENTS REGARDING WOOD WASTE POTENTIAL AVAILABLILITY AT

$20/Green Ton or Greater

AMOUNT POTENTIALLY 

AVAILABLE AT

$0 - $10/Green Ton

COMMENTS REGARDING WOOD WASTE 

POTENTIALLY AVAILABLE AT

$0-10/ Green Ton

Based on data provided in Assessment 7, about 24% of construction and renovation wood 

waste is either currently reused/recycled or is not usable (due to contamination, commingling, 

etc.) The amount reused /recycled only is not known. Assume 76% (100% - 24% = 76%) is 

available. 2,069,000 

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of construction wood 

waste potentially available is projected to be available 

at a delivered price of up to $10.

Based on data presented in Assessment 3, 39% of secondary mill residues are used by "noncaptive" (ie. low-value) markets or are unused and recoverable. The remaining 61% are used 

by high value markets and are assumed not to be available due to their market value. 1,342,000 

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of secondary mill 

residues potentially available are projected to be 

available at a delivered price of up to $10.

Based on survey results presented in Assessment 4, 88% of URTs generated are used in low 

value markets, disposed, or stockpiles.

The amount potentially available is assumed to be 88%. 9,962,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of UTRs are 

potentially available are projected to be available at a 

delivered price of up to $10.

About 23% of MSW wood is unacceptable for recovery (Assessment 7, 1998 data).

Based on data presented in Assessment 2, 4.5% of MSW wood waste was recycled in 1996. 

It is likely most, if not all markets for MSW wood waste are low-value markets such as mulch, 

compost amendment, or fuel.

The amount assumed to be available is that acceptable for recovery (100%-23%=77%). The 

amount recycled is also assumed to be available. 1,999,000 

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of MSW wood waste 

potentially available is projected to be available at a 

delivered price of up to $10.

According to Assessment 7, about 3.4 million tons, or 13.5% of yard waste generated in 1998 

was "disposed as unusable". The remainder was recycled, composted, or burned. It is likely 

no or minimal amounts were used in high value markets such as pulp and sawtimber.

The amount assumed to be available is 86.5% (100% - 13.5% = 86.5%). 1,199,000 

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of woody yard waste 

potentially available is projected to be available at a 

delivered price of up to $10.

Based on data provided in Assessment 7, about 24% of construction and renovation wood 

waste is either currently reused/recycled or is not usable (due to contamination, commingling, 

etc.) The amount reused /recycled only is not known. Assume 76% (100% - 24% = 76%) is 

available. 727,000 

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of construction wood 

waste potentially available is projected to be available 

at a delivered price of up to $10.

Based on data provided in Assessment 7, about 30% of demolition wood is considered 

recoverable. 1,742,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of demolition wood 

waste potentially available is projected to be available 

at a delivered price of up to $10.

An estimated 1,044,000 tons of used pallets are recycled as feedstock in low value markets, 

and are considered available. 230,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 22% of used pallets 

potentially available is projected to be available at a 

delivered price of up to $10.

TOTAL =

 19,270,000 

Page 4 of 5
ASSESSMENT 

NUMBER

WOOD WASTE ASSESSMENT

Author, Date of Report

1

Characterization of BuildingRelated Construction and 

Demolition Debris in the U.S.

Franklin Associates, Ltd, 1998

2

Characterization of Municipal 

Solid Waste in the U.S., 1997 

Update

Franklin Associates, Ltd, 1988

3

Lignocellulosic Feedstock 

Resource Assessment

NEOS 1998

4

Urban Tree Residues: Results 

of the First National Inventory

NEOS 1994

5

Urban Wood Waste Resoruce 

Assessment

Appel Consultants, Inc., 1998

6

Biomass Residue Sipply 

Curves for the U.S. (Update)

Antares Group Inc., 1999

7

The Changing Solid Waste 

Wood Resource in the U.S., 

1990-1998

David McKeever, 1999

8

9 Other wood waste

AMOUNT POTENTIALLY 

AVAILABLE AT

$10 = $20/Green Ton

COMMENTS REGARDING WOOD WASTE 

POTENTIALLY AVAILABLE AT

$10 - $20/Green Ton

5,832,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of construction wood 

waste potentially available is projected to be available at 

a delivered price of up to $20.

3,783,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of secondary mill 

residues potentially available are projected to be 

available at a delivered price of up to $10.

28,074,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of UTRs are potentially 

available are projected to be available at a delivered 

price of up to $10.

5,633,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of MSW wood waste 

potentially available is projected to be available at a 

delivered price of up to $20.

3,379,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of woody yard waste 

potentially available is projected to be available at a 

delivered price of up to $20.

2,050,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of construction wood 

waste potentially available is projected to be available at 

a delivered price of up to $20.

4,910,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of demolition wood 

waste potentially available is projected to be available at 

a delivered price of up to $20.

647,000

Using a similar methodology to that developed in 

Assessment 6, an estimated 62% of used pallets 

potentially available is projected to be available at a 

delivered price of up to $20.

TOTAL =

54,308,000

Page 5 of 5
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

C-1

Appendix C - Calculated Delivered Residue Cost

And Graph of DRC Versus Cumulative Percent Available
Page 1 of 1

Graph of DRC Versus Cumulative Percent of Wood Waste Available

y = -0.002x2 + 0.4237x + 1.5786

R

2

 = 0.9768

$0

$10

$20

$30

0 20 40 60 80 100

Cumulative Percent (of available wood waste)

DRC ($/green ton)
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

C-2
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

C-3

Calculated Delivered Residue Cost and Cumulative Percent of Wood Waste Available(a)

Transportation Percent Available

Distance

(miles)

Processing

Cost (b)

($/ton)

Transportation

Cost (c)

($/ton)

Incentive (d)

($/ton)

Delivered Residual

Cost (e)

($/ton) (Percent)

(Cumulative

Percent)

25 12 6.03 (12.25) 5.78 6 6

50 12 12.06 (12.25) 11.81 19 25

75 12 18.08 (12.25) 17.83 31 56

100 12 24.11 (12.25) 23.86 44 100

(a): Based on the equation developed by Antares Group Inc.

(b): Wood waste processing costs developed by Antares Group Inc. are assumed to apply to secondary mill residues

and urban wood wastes.

(c): Based on a transportation cost of 24.11¢/mile.

(d): Assumed to be 1⁄2 of the national weighted average landfill and incinerator tipping fee.

(e): The DRC is the sum of the processing, transportation, and incentive.
Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

D-1

Appendix D - Calculation of Weighted Average Landfill and

Incinerator Tipping Fee
Calculation of Weighted Average Landfill and Incinerator Tipping Fee for the U.S.

State SW Generation

Percent

Landfilled

Amount

Landfilled

Percent

Incinerated

Amount

Incinerated

Avg. Landfill 

Tipping Fee

Average 

Incinerator 

Tipping Fee

(Amt Landfilled) x 

(Avg Landfill 

Tipping Fee)

(Amt. Incinerated) x 

(Avg. Incinerator 

Tipping Fee)

(Tons/Yr) (%) (Tons/Yr) (%) (Tons/Yr) ($) ($) (Tons/Yr)*($) (Tons/Yr)*($)

Alabama 5630000 72 4053600 5 281500 33 40 133768800 11260000

Arizona 5142000 83 4267860 0 0 22 93892920 0

Arkansas 3316000 67 2221720 0 0 27 59986440 0

California 56000000 67 37520000 0 0 39 34 1463280000 0

Colorado 5085000 82 4169700 0 0 33 137600100 0

Connecticut 3047000 12 365640 64 1950080 64 64 23400960 124805120

Delaware 825000 48 396000 30 247500 58.5 58.5 23166000 14478750

DC 0 0 0 92 0 0 0

Florida 23770000 45 10696500 16 3803200 43 55 459949500 209176000

Georgia 10745000 66 7091700 0 0 28 198567600 0

Idaho 0 0 21 0 0

Illinois 13300000 71 9443000 0 0 28 264404000 0

Indiana 5876000 67 3936920 10 587600 30 27.5 118107600 16159000

Iowa 2518000 66 1661880 0 0 30.5 50687340 0

Kansas 2380000 87 2070600 0 0 23 47623800 0

Kentucky 6320000 68 4297600 0 0 25 107440000 0

Louisiana 4100000 81 3321000 0 0 23 76383000 0

Maine 1635000 18 294300 20 327000 47 47 13832100 15369000

Maryland 5700000 47 2679000 25 1425000 48 51 128592000 72675000

Massachusetts 0 21 0 45 0 0 0

Michigan 0 70 0 5 0 0 0

Minnesota 5010000 27 1352700 28 1402800 50 50 67635000 70140000

Mississippi 3070000 81 2486700 5 153500 18 18 44760600 2763000

Missouri 7950000 70 5565000 0 0 27 150255000 0

Montana 1001000 93 930930 2 20020 32 65 29789760 1301300

Nebraska 2000000 71 1420000 0 0 25 35500000 0

Nevada 2,800,000 86 2408000 0 0 23 55384000 0

New Hampshire 880000 54 475200 20 176000 55 55 26136000 9680000

New Jersey 7,800,000 37 2886000 20 1560000 60 51 173160000 79560000

New Mexico 2640000 90 2376000 0 0 23 54648000 0

New York 0 46 0 11 0 0 0

North Carolina 12575000 67 8425250 0 0 31 261182750 0

North Dakota 501,000 74 370740 0 0 25 9268500 0

Ohio 12335000 83 10238050 0 0 30 307141500 0

Oklahoma 2,545,000 78 1985100 10 254500 18 18 35731800 4581000

Oregon 4100000 59 2419000 11 451000 25 67 60475000 30217000

Pennsylvania 9,200,000 52 4784000 22 2024000 49 69 234416000 139656000

Rhode Island 420000 73 306600 0 0 35 10731000 0

South Carolina 10,010,000 56 5605600 2 200200 29 29 162562400 5805800

South Dakota 510000 58 295800 0 0 32 9465600 0

Tennessee 9,513,000 55 5232150 10 951300 35 43 183125250 40905900

Texas 0 65 0 1 0 0 0

Utah 0 75 0 3 0 0 0

Vermont 550000 63 346500 7 38500 65 65 22522500 2502500

Virginia 10,000,000 42 4200000 18 1800000 35 35 147000000 63000000

Washington 0 59 0 8 0 0 0

West Virginia 2,000,000 80 1600000 0 0 48 76800000 0

Wisconsin 5600000 61 3416000 3 168000 30 45.5 102480000 7644000

Wyoming 530,000 95 503500 0 0 10 5035000 0

TOTALS 268929000 5665887820 921679370

Weighted Average = [(Amt. Landfilled)x(Avg. Lanfill Tipping Fee) + (Amt. Incinterated)x(Avg. Incinerator Tippping Fee)]/(SW Generation)

Weighted Average = $ 24.4955627

Notes:

Bold numbers were adjusted from that presented in the BioCycle article to allow calculation of weighted average tipping fee

Blank spaces indicate that the corresponding data was not presented in the BioCycle article

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Secondary Mill Residues &

Urban Wood Waste Quantities in the U.S.

D-2