Materials Characterization Paper In Support of the Proposed Rulemaking – Identification of Nonhazardous Secondary Materials That Are Solid Waste Construction and Demolition Materials – Land Clearing Debris

March 18, 2010

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1. Definition of Land Clearing Debris

Land clearing debris is defined as growing stock and other timb er sources cut or otherwise destroyed in the process of convert ing forest land to non-forest uses. 1 Growing stock that is removed in silvicultural operations such as pre- commercial thinning is also included in this definition. Land clearing debris is typically in the form of tree tops and branches, trees cut or knocked down and left on site, and st umps. In non-forested areas, su ch as grasslands and desert, land clearing debris may include soil, rocks, an d shrubs, although fuel is primarily derived from previously forested areas.

2. Annual Quantities of Land Clearing Debris Generated and Used

(1) Sectors that generate Land Clearing Debris:

• NAICS 561730 Landscaping Services - This industry comprises (1) establishments primarily engaged in pr oviding landscape care and maintenance

services and/or installi ng trees, shrubs, plants, la wns, or gardens and (2) establishments primarily engaged in pr oviding these services along with the design of landscape plans and/or the constr uction (i.e., installation) of walkways, retaining walls, decks, fences, ponds, and similar structures (U.S. Census Bureau 2007).

• NAICS 11310 - This industry comprises esta blishments primarily engaged in one or more of the following: (1) cutting timber; (2) cutting and transporting timber; and (3) producing wood chips in th e field (U.S. Census Bureau 2007)..

• NAICS 236 – This subsector comprises es tablishments primarily responsible for the construction of buildings. The work performed may include new work, additions, alterations, or maintenance and re pairs. The on-site assembly of precut, panelized, and prefabricate d buildings and co nstruction of temporary buildings

are included in this subsector . (U.S. Census Bureau 2007).

(2) Quantities and Prices of La nd Clearing Debris Generated:

• In 2002, 30 million short tons of land cleari ng debris were generated in the U.S. According to a 2002 USDA Forest Service Study, 10 percent was considered to be unusable because of size, location, or other reasons. Based on this assumption,

1 This is distinct from forest derived biomass, which is extracted from logging oper ations on areas that will

remain forest land.Construction and Demolition Materials – Land Clearing Debris

27 million short tons of land clearing debr is were available for recovery in 2002 (McKeever 2002, p. 3-4).

• Paper mills sign one, two or three year contracts with supply companies for land clearing debris used as fuel. The pr ice per ton depends significantly on the

distance over which the material must be transported. One source identified for the development of this document sugge sts that ground wood that meets mill specifications commands a market pr ice ranging from $15 to $20 per ton (Goldstein 2006, p. 29).

• A developing market for biomass is exportation to Europe, where biomass demand has increased due to cap-and-trade policies and other efforts to reduce fossil fuel use and emissions (Yepsen 2008, p. 51).

(3) Trends in generation of Land Clearing Debris:

• Information was not readily available to ga uge the trend in the generation of land clearing debris.

3. Uses of Land Clearing Debris

(1) Fuel uses of Land Clearing Debris:

• Land clearing debris is comm only used as a fuel in indus trial boilers. In general, this material can be combusted for energy recovery if the processing capacity and

markets for the fuel exist. Furthermore th e thermal value of this material varies depending on its moisture content. Wood with a moisture content of 50 percent generally has a heating value betwee n 9 and 10 million btu/ton (4,500 to 4,980 btu/lb) (EPA 2003, EIA 2008c). The heating value for dry (0 percent moisture) woody materials 2 is typically between 15.5 and 16.4 million Btu/ton (7,750 to 8,200 btu/lb) (Wright et al. 2006). If oven dried, however, wood may produce approximately 9,000 Btu/lb when burned, a nd can also be conve rted to liquid or gaseous fuel. Mixed wood debris with so me green wood has a Btu value typically near 7,300 Btu/lb, and debris with higher percentages of green wood can have lower Btu values, though land clearing debris is typically dried as part of its processing. In addition, it is possible to pr oduce different forms of solid fuel from wood debris, such as charcoal (SW ANA 2002, p. 2, 24, 30, Goldstein 2006, p. 29).

• The combustor survey database devel oped by EPA for the 2009 proposal of the

Commercial and Industrial Solid Waste Incinerator (CISWI) standards and the Industrial Boilers Maximum Achievable Control Technology (MACT) standards indicates that the sources surveyed for these rules annually combust approximately 3.3 million tons of sec ondary wood material that may be construction and demolition disaster debris (EPA 2009). 3

, 4

2 Also called the gross or higher heating value.

3 Although we report wood quantities from the combustion database as tonnages, the database includes material quantities expressed in terms of heating values (Btu). To express this information as a tonnage, we assumed that wood has a heating value of 7,975 Btu per pound, which is the midpoint of the 7,750 to 8,200 Btu/lb range for wood reported by Wright (Wright 2006).

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(2) Non-combustion uses of Land Clearing Debris:

• Non-combustion beneficial use applica tions for land clearing debris include shredding for mulch and other land applica tions. Land clearing debris can also be composted.

(3) Quantities of Land Clearing Debris Landfilled:

• Information was not readily available to gauge the amount of land clearing debris that is disposed in landfills.

(4) Quantities of Land Clearing Debris Stockpiled/Stored:

• The data sources consulted in the devel opment of this document did not suggest that large quantities of land clearing debris are stored or stockpiled.

4. Management and Combustion processes for Land Clearing Debris

(1) Types of units using Land Clearing Debris:

• For combustion/fuel applications, land cl earing debris is primarily used by woodfired industrial boilers and burners. Mulch is sold to landscaping companies, suppliers, or retailers for use by re sidential and commercial customers.

• Public comments submitted on behalf of the American Forest and Paper Association indicate that forest products boilers are specifically designed to handle biomass, particularly the lower Bt u value material such as biomass with higher moisture content (Hunt 2009).

(2) Sourcing of Land Clearing Debris:

• Some companies that process land clea ring debris use wood derived from their own land. Other processors typically receive land clearing debris from land clearing companies and municipalities th at collect yard trimmings. Processing companies then provide wood chips to m ills with whom they have contracted (Goldstein 2006, p. 29).

(3) Processing of Land Clearing Debris:

• At processing facilities, land clearing debris goes through a multi-step process to produce marketable wood fuel. After the de bris arrives at the processing facility, it is inspected for contaminants, and an excavator is used to remove any

contaminants identified. A bulldozer with a rake then shakes the material to remove any soil that is attached to the debris. Fo llowing this step, the woody products are staged in stoc kpiles to dry prior to grinding. Processors then grind the debris so that it can easily be fed into an industrial boiler. The ground wood generally needs to be 2-inch minus in size and scope for most mills. Some

4 The categories of wood material in the combustion database that may contain C&D land clearing debris include (1) unadulterated wood and (2) unadulterated lumb er. Note that these categ ories could include building debris, disaster debris, or biomass (as defined in the three biomass materials characterization papers) rather than land clearing debris.

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processing facilities achieve the 2-inch minus size in one grind, whereas other processes will do double grindi ng (Goldstein 2006, p. 29).

After land clearing debris is processed, the mills that purchase wood fuel derived

from this material will often conduct a te st burn to evaluate the moisture content of the fuel. Mills prefer wood fuel with a low moisture content because it has a higher Btu value per pound (Goldstein 2006, p. 29).

(4) State status of Land Cleari ng Debris use as fuel:

• According to state respons es to a 2006 survey by the Association of State and Territorial Solid Waste Management O fficials (ASTSWMO), two states—New York and North Carolina—have approved th e use of recovered wood materials as a fuel source on at least one occasion, but it is unclear whether these approvals apply to wood debris from land clearing or the beneficial use of finished wood product. In both states, th e beneficial use of recovere d wood materials as a fuel does not appear to have pre-approve d status (ASTSWMO 2007, p.B-42).

5. Land Clearing Debris Composition and Impacts

(1) Composition of Land Clearing Debris:

• By definition, land-clearing debris is ma de up of cleared vegetation, and may

include rocks and soil.

(2) Impacts of Land Clea ring Debris use:

• Cost Impacts: The net cost impacts associated with the beneficial use of land clearing debris as a fuel depends on the avoided input or fuel costs for facilities

that use these materials and the cost of beneficial use itself. Information on the processing costs for land clearing debris is not readily available, but the fuel savings associated with usi ng this material as a substi tute for conventional fuels could be as follows, depending on the fuel replaced: 5

Natural Gas (Industrial): $7.35 / 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 Combustion: Exhibit 1 compares the emission factors for wood with the corresponding va lues for conventional fuel s that land clearing debris may displace. The estimates in th e exhibit suggest that the combustion of wood results in higher PM emissions than natural gas or distil late oil, but lower PM emissions than coal or residual oil syst ems. The data in Exhibit 1 also suggest

that wood results in lower SO 2 emissions than most conventional fuels. The

estimated NO

x emissions associated with wood combustion are similar to those

5 To express these values as dollars per MMBtu, the fo llowing 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).

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5 associated with distillate and lower than the NO

x emissions for other conventional

fuels. 6

Exhibit 1 also includes greenhouse gas em ission factors associated with the combustion of wood. It is unclear, however, whether the combustion of wood land clearing debris would lead to increased greenhouse gas emissions. Vegetative land clearing de bris, by definition, has already been removed from the ground and therefore has initiated decay. Combustion of this material merely accelerates the release of the stored carbon into the atmosphere.

• Lifecycle Emissions Impacts: Use of land clearing debris as a replacement for traditional primary fuels may eliminate the environmental impacts associated with extraction and processing of traditional fu els. In addition to the emissions impacts of combustion described above, E xhibit 1 lists the quantities of the total cradle-to-gate emissions for these fuels based on typical pro cesses in the United States in the late 1990s, with wood scrap combustion presented as a proxy for land clearing debris. Note that ther e may be impacts associated with the processing of land clearing debris into useab le fuel that are not accounted for in the values presented in Exhibit 1. In a ddition, there may be alternative uses (e.g., composting) that are environmentally preferable to combustion.

6 We note that the emission factors for wood presented in Exhibit 1 represent averages for wood-burning boilers. To the extent that these data reflect the combustion of finished wood product (e.g., C&D wood debris), they may not be representative emissions from the combustion of land clearing debris.Construction and Demolition Materials – Land Clearing Debris6Exhibit 1: Comparative Impacts of WoodCombustion versus Alternative Primary FuelsWoodCoalDistillate Fuel OilResidual Fuel OilNatural GasCombustionCombustionCombustionplusUpstreamCombustionCombustionplusUpstreamCombustionCombustionplusUpstreamCombustionCombustionplusUpstreamPollutant----------------------------------------- lb./MMBtu -------------------------------------Criteria PollutantsPM2.5---------PM100.0190.0540.0540.0110.0110.0930.0930.0090.009PM,unspecified--0.246-0.012-0.012-0.004NOx0.1670.4820.5040.1730.2340.3670.4280.3010.417VOCs-0.0060.0140.0010.3630.0020.3670.0090.524SOx0.0081.4461.4690.2090.3941.5931.7810.0731.985CO1.5110.0680.0850.0360.0820.0330.0790.0580.282Pb1.33x10-48.93x10-69.19x10-64.60x10-65.61x10-65.80x10-55.90x10-5-2.72x10-7Hg-2.05x10-62.14x10-61.58x10-61.77x10-68.67x10-68.85x10-6-7.18x10-8Greenhouse GasesCO2233.3210.7214.7161.2180.1173.3192.5114.6129.8CH4-0.0070.4583.74x10-40.030.0070.0360.0030.372N2O-0.0030.003-2.01x10-5-2.07x10-5-1.17x10-5MTCO2E/MMBtu0.1060.0960.1020.0730.0820.0790.0880.0520.062Source:Franklin Associates 1998.Note:“-” signifies data not available; may equal zero.The emission information presented in this table is derived from Life Cycle Inventory (LCI) data, as compiled by Franklin Associates. LCI data identifies andquantifies resource inputs, energyrequirements, and releases to the air, water,and land for each step in the manufacture of aproduct or process, from theextraction of the raw materials to ultimate disposal. The LCI canbe used to identify those systemcomponents or life cycle steps that are the main contributorsto environmental burdens such as energy use, solid waste, and atmospheric and waterborne emissions. Uncertainty in an LCI is due to the cumulative effects ofinput 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 readilyavailable LCI database that wasmost consistent with the materials and uses examined. These LCI data rely on system boundaries as defined by Franklin Associates, as described in thedocumentation for this database, available at:http://www.pre.nl/download/manuals/DatabaseManualFranklinUS98.pdf.Construction and Demolition Materials – Land Clearing Debris

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,.

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