Materials Characterization Paper

In Support of the

Advanced Notice of Proposed Rulemaking –

Identification of Nonhazardous Materials That Are Solid Waste

Construction and Demolition Materials – Building-Related C&D Materials

December 16, 2008

=====================================================================

1.	Definition of Building-Related Construction and Demolition Materials

Building-related construction debris and demolition (C&D) materials are
commonly grouped as a single type of material, despite the fact that
these two material streams come from different processes. Construction
materials originate from construction, repair or remodeling activities.
This materials stream typically consists of a variety of building
products (such as concrete, roofing, gypsum wallboard, wood products,
plastics, insulation, tile, and metal) as well as the packaging
materials that building materials arrive in (such as cardboard and
plastics). Construction materials are usually generated as a result of
cutting a material down to size for installation or purchasing materials
in excess of what is needed. Wood materials consists of wood scraps from
dimensional lumber, siding, laminates, flooring (potentially stained),
laminated beams, and moldings (potentially painted). Demolition
materials are generated from the dismantling of buildings or the removal
phase of remodeling. Typical constituents include concrete, wood, metal,
insulation, glass, carpet, and other building materials. Debris from
this process is often painted or chemically treated or is fastened to
other materials, making separation difficult (NESCAUM 2006).  For the
purposes of this summary, wooden railroad crossties and wooden utility
poles are also characterized as demolition materials.

This summary of C&D debris focuses largely on the scrap wood generated
from construction and demolition activities, as this is the main C&D
constituent beneficially used as a fuel.  EPA has also expressed
interest in obtaining information on the beneficial use of C&D plastics
and rubber, particularly fuel applications of these materials.  The
major plastic components of C&D materials (vinyl siding and PVC piping),
however, can contain 57 percent chlorine (Commission of the European
Communities, 2000).  Information on the quantities of vinyl siding and
PVC piping combusted in energy recovery facilities is not readily
available. In addition, rubber does not appear to be a major component
of C&D debris.  This C&D summary does not include a detailed examination
of either C&D plastic or rubber.

2.	Annual Quantities of C&D Materials Generated and Used

Sectors that generate C&D Materials: 

Construction Materials are produced by NAICS 236: Construction of
Buildings (U.S. Department of Labor 2008). Demolition Materials are
produced by NAICS 238910: Site Preparation Contractors (U.S. Census
Bureau 2007).

(2) Quantities and prices of C&D Materials generated:   

EPA estimates that 164 million tons of building-related C&D debris were
produced in 2003.  Approximately 47 percent of this was generated
through construction and renovation activities, and 52 percent was
generated through demolition activities (Franklin 2005).

Of the 164 million tons of building-related C&D materials generated in
2003, EPA estimates that between 33 and 49 million tons2 was C&D wood
(Franklin 2005).

As corroboration for EPA’s 2003 estimate of C&D wood debris
generation, a USDA source estimates that approximately 39.35 million
tons of C&D wood were generated in the U.S. in 2002.  Of this,
approximately 30 percent originated in construction activities and 70
percent in demolition activities (McKeever 2002).

Approximately 50 percent of C&D wood debris (20.28 million short tons)
is of acceptable size, quality, and condition to be considered available
for recovery. Factors limiting “availability” include contamination
and the commingling of wood with other nonwood building products
(McKeever 2002). 

The quantity data presented above do not reflect the generation of scrap
railroad ties or utility poles.  A 1995 analysis indicates that 13
million wooden crossties are removed from railroad service each year
(WasteAge 1995). A 2000 analysis reports that 1 to 2 million wooden
utility poles are replaced each year (Choong et. al. 2000, pg 1).

The available data on the market price of ground wood includes a range
of values.  Data for 2000 show a range of $11.16 to $12.50 per ton,
while 2006 data suggest a range of $15 to $20 per ton (Krause 2000,
Goldstein 2006).  These prices vary by region, with prices in the
Northeast lower than in the West (Krause 2000). 

Trends in generation of C&D Materials:  

Information on the trend in C&D wood debris generation is not readily
available; however, between 1998 and 2003 the generation of all
building-related C&D rose by approximately 17 percent, from 136 million
tons in 1998 to 164 million tons in 2003 (EPA 1998, Franklin 2005). 
Assuming that this growth rate applies to building-related C&D wood
debris, the generation of this debris grew from 28 to 42 million tons in
1998 to 33 to 49 million tons in 2003.

Trends in the generation of C&D debris tend to mirror the trend in
economic activity (McKeever 2002).  That is, a strong economy generally
results in more construction and demolition activity.  For example, the
annual percentage change in U.S. Gross Domestic Product (GDP) in 2006
decreased from 2.8 to 2.0 in 2007. During the same time period, total
U.S. new housing starts decreased from 1,800 to 1,355 (thousands) (U.S.
Census Bureau 2008, U.S. Department of Commerce 2008).

On a more local scale, the rate of C&D debris generation is heavily
influenced by a number of area-specific factors including the age of the
building stock (SWANA 2002b).

3.	Uses of C&D Materials

Fuel uses of C&D Materials:  

C&D wood residues are commonly used for boiler fuel. The biomass can
either be combusted directly to heat a conventional type of boiler and
produce steam for power production, or it can be converted into gaseous
components (carbon monoxide, hydrogen, methane, and other inert gases)
through gasification. In contrast to incineration, which fully converts
the input debris into energy and ash, gasification deliberately limits
the conversion so the biomass is converted into the intermediate
products of gas and charcoal, which can be used for further energy
recovery (NRI).

Oven-dry wood produces approximately 9,000 Btu/lb when burned (SWANA
2002a).  

Information on the quantity of C&D materials combusted for energy
recovery is unavailable.

Railroad ties are in demand for combustion due to their low moisture
content. In addition, because most crossties are creosote-treated, the
chips reportedly allow boilers to burn at a higher temperature than they
would with untreated wood chips. Furthermore, treated wood chips from
railroad ties reportedly leave less combustion residue behind than
untreated chips (WasteAge 1995).

Asphalt shingles can be used as fuel in cement kilns, and the mineral
components remaining after combustion can serve as raw material for the
cement (EPA 2008, p. 23).  However, while the use of asphalt shingles as
fuel is an established market in Europe, this use is limited in the
United States because of air pollution concerns and concerns about the
previous use of asbestos in older shingles (Shingle Recycling.org 2007).

Non-combustion uses of C&D Materials:

EPA estimates that 48 percent (65.6 million tons) of C&D materials were
recovered for beneficial use (including recycling and use as a fuel) in
2003 (Franklin 2005).  A corresponding estimate specific to wood C&D is
not readily available.

Approximately 3,500 C&D recycling facilities are operating in the U.S.
(Franklin 2005).  

Additional markets for C&D wood include flooring, feedstock for
engineered woods, landscape mulch, soil conditioner, animal bedding,
compost additive, and sewage sludge bulking medium. Reusing wood as
lumber can potentially yield revenues 20 to 32 times higher than those
from selling wood for fuel or mulch. Similarly, recycling wood to the
manufacturing of engineered wood products can potentially generate
revenues four times greater than the revenues generated from selling the
same amount of wood for fuel or mulch. However, processing and handling
costs associated with the reuse of lumber and engineered wood product
feedstock options are also much greater than those associated with using
debris wood for fuel or mulch. Therefore, some of the revenues
associated with more “high-end” applications are offset by greater
processing and handling costs (SWANA 2002a).

More than half of scrap railroad ties are reused in landscaping,
fencing, construction, retaining walls and as fuel for utilities and
other plants (WasteAge 1995).

Quantities of C&D Materials landfilled: 

Most C&D materials are non-hazardous and are frequently accepted at C&D
and municipal solid waste (MSW) landfills, depending on the state and
local laws governing disposal (EPA 2004).

As indicated in Exhibit 1, EPA estimates that 98.4 million tons of
building-related C&D debris were disposed in 2003 (Franklin 2005).  A
corresponding estimate specific to wood C&D is not readily available.

A 1994 EPA survey identified approximately 1,900 active C&D landfills in
the United States. (EPA 1998). 

In 1998, EPA estimated that 45-60 million tons of C&D debris were
disposed of in permitted C&D landfills. This amount is equal to about
35-45 percent of the estimated 136 million tons of building related C&D
debris produced that year (EPA 1998).

Less than half of scrap railroad ties are landfilled (WasteAge 1995).

Quantities of C&D Materials stockpiled/stored:

Construction and demolition debris is not believed to be stockpiled in
significant quantities.  The data sources consulted for the development
of this document provided no indication that large quantities of C&D
materials are stockpiled. 

 Exhibit 1:  C&D Material Quantities Generated and Managed in 2003

Material	Quantity Generated (million short tons)	Quantity Recycled or
used as Fuel (million short tons)	Percent Recycled or used as Fuel
Quantity Disposed

(million short tons)	Percent Disposed



	Building Related C&D Materials 	164 million	65.6	40%	98.4	60%



Sources:

Franklin 2005



4.	Management and Combustion processes using C&D Materials

Types of units using C&D Materials:

C&D wood is used by wood-fired industrial boilers and burners.

Sourcing of C&D Materials:

Wood from C&D activities becomes available as combustion fuel through a
variety of methods, but it is typically sent to a processing facility by
municipal haulers, private haulers, construction companies, or
individual households. After the wood is processed according to
combustor specifications, it is delivered to combustion facilities
(NESCAUM 2006).

Processing of C&D Materials:  

Prior to use as fuel, scrap wood typically requires removal of non-wood
materials and processing into chips. Fuel specifications for combustors
usually include minimum and maximum chip sizes, amount of C&D fines,
maximum moisture content, and maximum contaminant levels (NESCAUM 2006).
 

A “hog” (also called a shredder or tub grinder) is used to process
construction and demolition wood materials. The hog uses rotating
hammers and stationary anvils to smash, crush and tear large wood into
smaller fragments. The maximum output particle dimension of hogged fuel
is typically less than 3 inches. Hogged fuel often has a high moisture
content and a significant ash content (from 2 to 20 percent) (Natural
Resources Canada 2000).  

State status of C&D Materials use as fuel:  

According to state responses to a 2006 survey by the Association of
State and Territorial Solid Waste Management Officials (ASTSWMO), two
states—Maine and Michigan—have approved the use of wood C&D
(excluding railroad ties) as fuel on at least one occasion.  In
addition, the following states have approved the use of railroad ties as
fuel on at least one occasion: Maryland, Pennsylvania, Iowa, Michigan,
and North Dakota.  

5.	C&D Materials Composition and Impacts

Composition of C&D Materials:

As indicated in Exhibit 2, EPA estimates that concrete rubble makes up
40 to 50 percent of building-related C&D materials and that wood makes
up 20 to 30 percent of this material.

Exhibit 2:  Average Composition of Building-related C&D Materials

Building-Related C&D Material	Quantity Generated

(million tons)	Percent of C&D Debris Stream





Concrete Rubble	66 to 83	40-50%

Wood	33 to 49	20-30%

Gypsum Drywall	8 to 25	5-15%

Asphalt Roofing	2 to 16	1-10%

Metals	2 to 8	1-5%

Bricks	2 to 8	1-5%

Plastics	2 to 8	1-5%

Total	164	100%



Source: 

Sandler 2003



A 2004 analysis of the composition of C&D wood chips used as fuel
conducted by the Maine Department of Environmental Protection found that
approximately 60 percent were untreated wood, 20 to 26 percent were C&D
fines, and less than 10 percent were painted wood, pressure-treated
wood, non-burnables, and plastic (NESCAUM 2006).

The rapid growth in the use of CCA-treated wood into the 1990s may
translate into future growth of this material as a component of C&D.
While information on national generation rates is not readily available,
some states do have data. For example, approximately 450 tons of
CCA-treated wood was disposed of in Florida in 1996, and this figure was
expected to quadruple by 2006. Recovered wood from C&D processing
facilities in Florida was found to contain, on average, six percent
CCA-treated wood in 1996. It should be noted that Florida’s
utilization of treated wood may be greater than utilization in many
states due to the extensive use of treated wood for marine applications
(Iida 2004). 

Impacts of C&D Materials use:

Cost Impacts: The net cost impacts associated with beneficial use
applications for construction and demolition materials depend on the
avoided input or fuel costs for facilities that use these materials and
the cost of beneficial use itself.  Both of these vary by C&D material
and application, as fees charged at the processing site for delivered
loads of recovered wood are based in part on local competitive disposal
market rates. Construction wood and chemically treated wood often incur
higher tipping fees, whereas a number of operations will pay for sawmill
residue. The unit fuel savings for C&D used as a fuel (e.g., C&D wood
burned in a boiler) would equal the savings from the fuel replaced net
of the cost of the C&D wood and processing costs. Estimates of the
average price of processed wood used as fuel in 2000 ranged from $11.16
to $12.50 per ton net of transportation (Krause 2000). The going rates
of fossil fuels that could be readily replaced by C&D wood are as
follows: 

Natural Gas (Industrial): $7.35 / million Btu (MMBtu) (EIA 2008a, Table
20)

No. 2 Distillate (Industrial): $16.80 / MMBtu (EIA 2008b, Table 36)

Residual Fuel Oil Average:  $9.19 / MMBtu (EIA 2008b, Table 38)

Coal – Average Delivered Price in 2006: $2.23 / MMBtu (EIA 2007, Table
ES1)

Emissions Impacts of Using C&D Wood Debris as a Fuel: To evaluate the
environmental impacts of burning C&D wood debris, we examined the
emissions associated with burning wood debris in a boiler and compared
these values to the emissions associated with the combustion of
conventional fossil fuels, as summarized in Exhibit 3.  The estimates in
the exhibit suggest that the combustion of wood results in higher PM
emissions than natural gas or distillate oil, but lower PM emissions
than coal or residual oil systems. The data in Exhibit 3 also suggest
that wood results in lower SO2 emissions than most conventional fuels. 
The estimated NOx emissions associated with wood combustion are similar
to those associated with distillate and lower than the NOx emissions for
other conventional fuels.  

The emissions profile of treated woods or wood with lead paint may
differ from the values presented in Exhibit 3.  For example, concerning
the combustion of railroad ties, the creosote in the ties increases the
combustion temperature, resulting in a more complete combustion of some
organics such as benzene, formaldehyde, and dioxins.  However, the
creosote itself contains 200 to 300 chemicals (Reid 2002).  In addition,
wood treated with chromium copper arsenate (CCA-treated wood) contains
arsenic, copper, and chromium that may be emitted when this wood is
combusted (Iida et al. 2004).  Similarly, lead may be emitted during the
combustion of lead-painted wood. Information on the magnitudes of these
emissions is not readily available.

Lifecycle Emissions Impacts: Use of C&D wood debris as a replacement for
traditional primary fuels may eliminate the environmental impacts
associated with extraction and processing of traditional fuels.  In
addition to the emissions impacts of combustion described above, Exhibit
3 lists the quantities of the total cradle-to-gate emissions
(“Combustion plus Upstream”) for these fuels based on typical
processes in the United States in the late 1990s, with wood scrap
combustion presented as an indicator of the emissions likely from the
combustion of C&D wood debris.  Note that there may be impacts
associated with the processing of C&D wood debris into useable fuel that
are not accounted for in the values presented in the exhibit.  In
addition, there may be alternative uses (e.g., composting) that are
environmentally preferable to combustion.  

Exhibit 3:  Comparative Impacts of Wood Combustion versus Alternative
Primary Fuels

Pollutant	Wood1	Coal	Distillate Fuel Oil	Residual Fuel Oil	Natural Gas

	Combustion	Combustion	Combustion plus Upstream	Combustion	Combustion
plus Upstream	Combustion	Combustion plus Upstream	Combustion	Combustion
plus Upstream

	-------------------------------------- lb./MMBtu
-----------------------------------

Criteria Pollutants

PM2.5	-	-	-	-	-	-	-	-	-

PM10	0.019	0.054	0.054	0.011	0.011	0.093	0.093	0.009	0.009

PM, unspecified	-	-	0.246	-	0.012	-	0.012	-	0.004

NOx	0.167	0.482	0.504	0.173	0.234	0.367	0.428	0.301	0.417

VOCs	-	0.006	0.014	0.001	0.363	0.002	0.367	0.009	0.524

SOx	0.008	1.446	1.469	0.209	0.394	1.593	1.781	0.073	1.985

CO	1.511	0.068	0.085	0.036	0.082	0.033	0.079	0.058	0.282

Pb	1.33x10-4	8.93x10-6	9.19x10-6	4.60x10-6	5.61x10-6	5.80x10-5	5.90x10-5
-	2.72x10-7

Hg	-	2.05x10-6	2.14x10-6	1.58x10-6	1.77x10-6	8.67x10-6	8.85x10-6	-
7.18x10-8





Source:

Franklin Associates 1998.

Note:

“-” signifies data not available; may equal zero.

1. Estimates of the metals emissions associated with the combustion of
CCA-treated wood are not readily available. 

The emission information presented in this table is derived from Life
Cycle Inventory (LCI) data, as compiled by Franklin Associates.   LCI
data identifies and quantifies resource inputs, energy requirements, and
releases to the air, water, and land for each step in the manufacture of
a product or process, from the extraction of the raw materials to
ultimate disposal. The LCI can be used to identify those system
components or life cycle steps that are the main contributors to
environmental burdens such as energy use, solid waste, and atmospheric
and waterborne emissions.  Uncertainty in an LCI is due to the
cumulative effects of input uncertainties and data variability.  

There are several life cycle inventory databases available in the U.S.
and Europe.  For this paper, we applied the most readily available LCI
database that was most consistent with the materials and uses examined.
These LCI data rely on system boundaries as defined by Franklin
Associates, as described in the documentation for this database,
available at:   HYPERLINK
"http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf" 
http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf .  



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 Building-related C&D debris does not include debris generated from the
construction and demolition of roads.  The available data suggest that
most road-related debris is not useable as a fuel; therefore, we exclude
these materials from this document.  

 Data currently under revision.

 Although disaster debris is not considered C&D material, the
construction of new structures following a natural disaster increases
the generation of construction debris.

 The primary exception to this is wood treated with chromated copper
arsenate (CCA).

 The ASTSWMO survey also indicates that New York and North Carolina have
approved the use of recovered wood materials as a fuel on at least one
occasion but does not specify whether these approvals apply to the
beneficial use of finished wood products or vegetative debris generated
through land-clearing or natural disasters (ASTSWMO 2007, p.B-42).

 To express these values as dollars per Million Btu (MMBtu), the
following thermal conversion factors were used: 1,031 Btu per 1,000
cubic foot of natural gas, 138,690 Btu per gallon of Number 2
distillate, 149,690 Btu per gallon of residual fuel oil, and 22,473,000
Btu per short ton of coal (EIA 2005, Tables A1, A4, and A5).

 We note that the emission factors for wood presented in Exhibit 3
represent averages for wood-burning boilers.  In addition, the wood
reflected in the emissions data may include wood other than C&D wood
debris. Emission factors for conventional fuels are based on typical
boilers in use in North America in the late 1990s.

Construction and Demolition Materials – Building-related C&D Materials

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