United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

Research Paper

RMRS-RP-50

August 2004

Wood Wastes and Residues 

Generated Along the Colorado 

Front Range as a Potential 

Fuel Source

Julie E. Ward

Kurt H. Mackes

Dennis L. Lynch
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 Rocky Mountain Research Station

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Ward, Julie E.; Mackes, Kurt H.; Lynch, Dennis L. 2004. Wood wastes and residues generated along 

the Colorado Front Range as a potential fuel source. Res. Pap. RMRS-RP-50. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 9 p.

Abstract

Throughout the United States there is interest in utilizing renewable fuel sources as an alternative to coal and natural gas. This project was initiated to determine the availability of wood wastes and residues for use as fuel in cement kilns and power plants located along the Colorado Front Range. Research was conducted through literature 

searches, phone surveys, personal communications, and public meetings to determine the types of wood wastes 

and residues generated. Four main sources were identified: municipal solid waste, construction and demolition 

debris, primary and secondary wood processing residues, and forest residues. Quantities of wood wastes and 

residues generated were estimated, separated into components, and further evaluated to determine availability 

for recovery and utilization. Overall, the results of this project made it evident that substantial quantities of wood 

wastes and residues exist. However, the recovery costs currently present a significant barrier to utilizing this material as an alternative fuel.

Key words: Wood waste, residue generation, recovery, utilization, municipal solid waste, construction and 

demolition debris, primary and secondary processors, forest residues, renewable fuel alternatives

The Authors

Julie E. Ward is a Research Associate with the Colorado State Forest Service at Colorado State University in 

Fort Collins, Colorado. Kurt H. Mackes is an Assistant Professor at Colorado State University in the Department 

of Forest, Rangeland, and Watershed Stewardship in Fort Collins, Colorado. Dennis L. Lynch is a Professor 

Emeritus at Colorado State University in the Department of Forest, Rangeland, and Watershed Stewardship in 

Fort Collins, Colorado.

Acknowledgments

The Colorado State Forest Service funded this research. The authors also wish to thank Tim Rooney and Randy 

Hunsberger of McNeil Technology and John Zerbe, Forest Products Lab, for their reviews.
Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Municipal Solid Waste (MSW) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Construction and Demolition Debris (C&D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Primary and Secondary Processing Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Forest Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Potential for Utilizing Wood Wastes and Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Wood Wastes and Residues Generated Along the 

Colorado Front Range as a Potential Fuel Source

Julie E. Ward

Kurt H. Mackes

Dennis L. Lynch

USDA Forest Service RMRS-RP-50. 2004 1

Introduction

During 1999 energy consumption totaled 

1,226.6 trillion BTUs in Colorado, with wood energy providing less than 1% of this total (DOE 

1999). An estimated 18.17 million tons (355.2 trillion BTUs) of coal and 316 billion cubic feet (318.2 

trillion BTUs) of natural gas were consumed. Wood 

energy consumption amounted to 10.3 trillion 

BTUs. Along the Colorado Front Range there are 

significant quantities of wood wastes and residues 

from residential and commercial sources that are 

discarded in landfills. This wood could be recovered and utilized as a renewable fuel source. In 

addition to urban residue generation, and because 

of the overstocked condition of forests in many areas along the Front Range, small diameter wood 

material from forest restoration and fire mitigation 

efforts could also be another fuel source.

There are needs to identify potential wood 

sources for recovery and to determine if there are 

sufficient quantities of low cost wood to supply 

potential users such as cement kilns and power 

plants. This report characterizes wood wastes and 

residues for Colorado Front Range counties to determine which components can be utilized as a fuel 

source, and assesses the quantity of wood available.

Methodology

The study area was comprised of 18 Colorado 

counties highlighted in figure 1. Counties that 

were included for study were either intersected by 

or were close in proximity to the I25 corridor extending from Fort Collins to Pueblo, Colorado. This 

includes the region generally referred to as the 

Colorado Front Range.

Data sources for residue generation and use 

were obtained from literature and internet searches, personal contacts, a telephone survey, and 

public meetings. Wood residues and wastes were 

categorized into four specific groups/sources 

based on how they were generated:

• Municipal Solid Waste Stream (MSW);

• Construction and Demolition Debris (C&D);

• Primary and Secondary wood processing residues (P&S); and

• Forest residues.

These categories or residue sources were 

evaluated further, dissecting them into smaller 

components to determine which elements are recoverable for use.

For MSW, U.S. Environmental Protection Agency 

(EPA 2003) information provided a general assessment of the municipal waste stream composition 

Figure 1—Colorado Front Range 

counties where primary and 

secondary wood processors 

were surveyed by Ward (2000).
2 USDA Forest Service RMRS-RP-50. 2004

and components. Estimates of MSW wood generation for Colorado Front Range counties are based 

on per capita consumption nationally multiplied by 

area population. Values and estimates that address 

local sources came from previous studies done 

within Larimer County reported by Lynch (1999).

National statistics and summaries provided information on C&D debris generation (EPA 1998; 

McKeever 1998). To determine the amount of C&D 

generated annually in the Front Range region, data 

from a pilot project study completed by the City of 

Fort Collins (2000) that worked with local development projects to separate clean construction woody 

materials at building sites and divert them from the 

MSW stream were used. From this study, an estimate of wood debris generated per square foot of new 

residential construction was obtained and multiplied by the average floor space in a new unit (NAHB 

2001) to arrive at an average amount of woody debris 

generated when new housing units are constructed. 

This amount was then multiplied by the number of 

new housing units authorized in the Front Range region during 2002 (US Census Bureau 2004).

Primary and secondary wood processing survey 

information from the region was evaluated. A survey completed by the New Energy – Environmental 

Options & Solutions Corporation (NEOS 1993a) 

evaluated P&S processors in the Denver metropolitan area. A telephone survey by Ward (2000) 

covered a broader area, which included the counties highlighted in figure 1. The telephone survey 

was conducted to evaluate the amount of residues 

available and current methods of disposal. A total 

of 173 P&S processors were contacted, with 75 

responses. There were many reasons that companies gave for not responding, which included 

being disconnected, relocated and no forwarding 

number, retired, closed, or no longer involved in 

processes that generated wood residues.

Information related to forest residue generation 

came from regional data in Larimer County and 

along the Front Range (NEOS 1993b; Lynch 1999 

and 2000). Estimates of residue generation were 

derived from harvesting data, which was used to 

determine how many tons per acre of wood debris 

would be generated, multiplied by the total acres 

treated in Colorado during 2001 (USDI 2002). 

Analyses of transportation and other economic 

cost factors were also assessed.

Results and Discussion

Municipal Solid Waste (MSW)

MSW comes from materials disposed of by residential, commercial, industrial, and institutional 

facilities. A study done by the EPA (2003) categorized 

materials in MSW as being glass, metal, plastic, food 

scraps, wood, yard trimmings, paper, rubber, leather, and textiles, and “other” miscellaneous wastes. 

The amount generated and percent of MSW for each 

category nationally is shown in figure 2.

Wood wastes from these sources can be separated into three categories: wood, yard trimmings, and 

paper (including paperboard). The wood consists of 

discarded furniture, cabinets, pallets, containers, 

scrap lumber and panels from activities other than 

C&D projects, and wood residues from manufacturers. Data describing the percentage that each 

specific component comprises was unavailable. 

Yard trimmings consist of branches, stumps, and 

other woody debris. The paper category consists 

of corrugated cardboard, newspapers, magazines, 

telephone books, paper bags, packaging and cartons, office papers, third-class mail, and other 

commercial printings.

In 2001, the largest component of MSW was paper, which amounted to 81.8 million tons (35.7% 

of MSW) or almost 575 pounds per capita (EPA 

2003). Yard trimmings contributed an additional 

28.0 million tons (12.2% of MSW) or about 197 

pounds per capita (12.2% of total MSW generation), making it the second largest component of 

MSW, while wood wastes totaled 13.2 million tons 

(5.7% of MSW) or about 93 pounds per capita (EPA 

2003). Considering that the 18 Colorado Front 

Range counties in the study area had a combined 

population of 3.62 million in 2000 (US Census 

Bureau 2004), MSW generated in this area during 

2000 included an estimated 1.04 million tons of 

paper, 170 thousand tons of wood wastes, and 360 

thousand tons of yard trimmings.

Figure 3 shows paper, wood, and yard trimmings separated into materials recovered for 

recycling and those that were discarded in 2001 

nationally. This figure shows that while relatively high percentages of paper and yard trimmings 

were recovered for recycling in 2001, only a small 

percentage of wood waste was recovered.

In 1996, the Larimer County landfill received a 

total of 187,237 tons of MSW (Lynch 1999). In the 

residential waste stream, wood waste amounted 

to 2410 tons and contributed 3.9% of the overall 

residential total. Wood constituted 27.7% or an estimated 29,563 tons of commercial waste. In 1997, 

Waste Management opened another landfill locally and this reduced the amount of MSW received 

by the Larimer County landfill in 1997 to 166,683 

tons. Wood made up approximately 26,318 tons of 

this total, which amounts to about 72 tons per day 

(Lynch 1999). At a county meeting in March 2000, 

it was reported that 90 tons of wood was delivered 

to the Larimer County landfill daily (Henderson 
USDA Forest Service RMRS-RP-50. 2004 3

Paper

(35.7%)

81.8 million tons

Other

7.8 million tons

(3.4%)

Glass

12.6 million tons

(5.5%)

Wood

13.2 million tons

(5.7%)

Rubber, leather, and textiles

16.3 million tons

(7.1%)

Metals

18.1 million tons

(7.9%)

Plastics

25.4 million tons

(11.1%)

Food scraps

26.1 million tons

(11.4%)

Yard trimmings

28.0 million tons

(12.2%)

0

5

10

15

20

25

30

35

40

45

50

Recovered for recycling Discarded

Paper (81.8 million

tons)

Wood wastes (13.2

million tons)

Yard trimmings

(28.0 million tons)

Figure 2—Categorized materials 

in MSW generated nationally 

during 2001 (EPA 2003).

Figure 3—Wood residue in MSW 

generated nationally during 2001 

(EPA 2003).
4 USDA Forest Service RMRS-RP-50. 2004

2000). Depending on the extent of sorting efforts, 

an estimated 50 to 75% of that material or 45 to 70 

tons per day could be recovered.

Construction and Demolition Debris (C&D)

C&D materials are generated from new construction, renovation, and demolition of residential 

and commercial buildings. An EPA study (1998) 

identified the quantities and types of debris and 

how they vary from one type of project to the next. 

The major constituents of C&D debris are concrete, asphalt, wood, metals, gypsum wallboard, 

roofing, and flooring tiles. Land-clearing debris 

such as rocks, stumps, dirt, and sweepings can 

also be considered as part of C&D.

It was estimated that 136 million tons of C&D 

debris were generated in the United States during 

1996 (EPA 1998). Building demolition accounted 

for 48% of the waste stream, renovations were 

44%, and the remaining 8% came from construction projects. Of total debris generated, 43% were 

from residential projects, and the remaining 57% 

were from non-residential projects. At non-residential demolition sites, concrete was the largest 

component contributing to waste (table 1). Wood 

was the largest component at residential construction and renovation sites (table 2).

It was also estimated that 35 to 45% of C&D 

wastes were discarded in C&D landfills (EPA 

1998). In Colorado, there are five C&D landfills. 

Approximately 30 to 40% of C&D debris is managed at MSW landfills or other landfills that were 

not permitted, and the remaining 15 to 35% were 

recovered and utilized.

Wood components in C&D debris consist of 

framing lumber, stumps from land clearing, plywood, particleboard, oriented strandboard (OSB), 

dimensional lumber, pressure treated wood, 

and painted wood. The difference between construction debris and demolition debris is that 

construction wastes tend to be cleaner and more 

easily separated. Demolition debris may consist 

of commingled aggregates, concrete, metal, insulation, and other building materials. Demolition 

materials also tend to be older, so contaminants 

such as asbestos, lead-based finishes, mercury, 

and polychlorinated biphenyls commingle with 

wood preventing recovery. One way that demolition crews are trying to minimize commingling and 

potential contamination is to remove valuable components first, deconstructing them, and diverting 

them from demolition rubble to increase recovery. 

Deconstruction methods can potentially separate 

70% by volume, 76% by weight (EPA 1998), of recoverable materials from total demolition waste.

In 1996, C&D wood debris amounted to 33.2 

million tons in the United States (McKeever 1998). 

Figure 4 shows the quantity of wood wastes that 

were generated from construction and demolition 

projects and the amount available for recovery.

The City of Fort Collins facilitated a wood separation and recycling program in response to its 

end-of-year report in 1998 which revealed that 

approximately 55% of the city’s waste generation 

came from construction debris, of which wood 

comprised a large portion. Eight construction 

companies were involved with this project and 13 

construction sites were evaluated. This pilot program started in July and ended mid-November 

2000. The two goals of this project were (1) to 

evaluate the quantities of wood volume that were 

generated from construction of new structures 

(residential and commercial) in Fort Collins and 

(2) assess factors that would encourage or hinder future recycling of wood materials (City of Fort 

Collins 2000).

Of the 13 sites that contributed construction 

debris, 11 were residential developments and the 

remaining two were commercial. The building sizes 

ranged between 1,500 and 8,500 square feet. For 

all sites evaluated, the average building size was 

3,485 square feet. By the end of the study, 330 

cubic yards or approximately 75,000 pounds of 

wood material were diverted from the landfill waste 

Table 1—Composition of demolition debris from nonresidential sources (EPA 1998).

Debris Percent

Concrete 66

Wood 16

Landfill debris 9

Scrap iron 5

Asphalt 2

Brick 1

Roofing 1

Table 2—Composition of construction debris from residential 

sites (EPA 1998).

Debris Percent

Wood 42

Drywall 27

Misc. 15

Brick 6

Roofing 6

Metal 2

Plastic 2
USDA Forest Service RMRS-RP-50. 2004 5

stream. Considering all buildings, wood debris 

amounted to 1.72 pounds per square foot with a 

volume of 7.27 cubic yards per 1000 square feet.

Based on this research, companies involved 

with separating materials were able to divert on 

average 39.3% of their residues from the landfill. The amount of residues diverted ranged from 

28.57% to 62.50%. As a result, participating companies experienced considerably lower bills for 

trash removal.

Woody debris collected during the study was 

characterized into two building material categories: (1) dimensional lumber and (2) composite 

panels, including plywood, oriented strandboard, 

and particleboard. Based on estimates, 38% of the 

material collected was dimensional lumber and 

59% was composite panels. The remaining 3% 

was comprised of trash and contaminated materials. The wood residues that were collected at the 

Larimer County landfill were set aside for processing into landscape mulch.

To determine estimates of total annual C&D debris generated by Colorado Front Range counties, 

data from the research done by the City of Fort 

Collins (2000) were used. Based on the study, it 

was estimated that an average of 1.72 pounds of 

wood debris per square foot was generated in new 

residential housing construction. Considering that 

the average size of a new residential housing unit 

is 2,200 square feet (NAHB 2000), each new unit 

that is built generates an average of 3,780 pounds 

of wood wastes and residues. In 2002, 40,340 new 

housing units were constructed in Colorado Front 

Range counties (US Census Bureau 2004). Based 

on the number of new housing units constructed 

and estimates of average wood residue generation 

per new housing unit, over 76,200 tons of wood 

wastes and residues were generated from the construction of new housing units in the region during 

2002.

Primary and Secondary Processing Residues

Primary processing includes the production of 

roundwood, lumber, and composite panel products. Residues from primary processing include 

bark, sawmill slabs and edging, sawdust, and 

peeler log cores. It has been estimated that 30.3 

million tons of bark and 86.7 million tons of wood 

residues were generated in the United States during 1997 (McKeever 1998). Most of these residues 

were used in producing other materials such as 

paper, leaving only about 5% of bark and 6% of 

wood residues remaining that could potentially be 

recovered for alternative uses.

In Colorado, residues from primary processing 

were estimated to be about 115,000 bone-dry tons 

in 1993 (NEOS 1993a). There were approximately 

100 mills in Colorado at the time of the survey, 

and on average, for every 1 million board feet 

0

2

4

6

8

10

12

14

16

18

20

Recovered, combusted, or not usable Available for recovery

Construction debris

(7.1 million tons)

Demolition debris

(26.1 million tons)

Figure 4—Quantity of wood waste 

generated from construction and 

demolition sites in the United 

States during 1996 (McKeever 

1998).
6 USDA Forest Service RMRS-RP-50. 2004

• Given away

• Stockpiled on site

• Sold for other products/uses

The two most significant means of end use/

disposal were landfill disposal (37%) and given 

away (36%). Both serve to get rid of material either 

at an expense or, at best, no additional cost. In the 

case of landfill disposal, further consideration for 

using the wood as a byproduct is eliminated.

From the results of the survey, the total quantity of wood residue generation was conservatively 

380 tons per week (19,760 tons annually) along 

the Front Range. Of those that responded, 49% 

were definite in their willingness to utilize their 

residues for alternative uses. Another 20% would 

strongly be in favor of alternative uses and 31% 

would likely not consider alternatives because 

they were currently utilizing their residues, selling 

them for use as a byproduct, or did not generate 

enough residues to consider the effort.

Forest Residues

Forest residues could come from a variety of 

activities on private and public lands. This would 

include activities such as traditional logging 

operations, forest restoration work, and road construction. In addition, wood removal on private 

land can also result from landowners implementing best management practices or providing for defensible space around structures.

Forest restoration and fuel hazard reduction 

projects could provide a significant source of wood 

supply. These projects are designed to improve 

forest health and mitigate conditions favorable for 

catastrophic wildfire. The Colorado State Forest 

Service has identified Red Zone Regions across 

the state where the conditions are favorable for 

catastrophic fire. Over 6.3 million acres of forests 

statewide are considered as “buffered high” risk 

for catastrophic wildfire. About 2.4 million acres 

Table 4—Percent distribution of wood residues generated by 

Colorado processors surveyed by Ward (2000).

Residue Percent

Sawdust 39

Scrap 35

Shavings/chips 16

Pole peelings 6

Pallets 1

Dunnage 1

Fines 1

Firewood 1

processed there were 576 bone-dry tons of residue 

generated.

Secondary processing utilizes primary forest 

products and further manufactures them into 

other products. Residues from secondary processing include sawdust, shavings, wood chips, sander 

dust, and solid wood residues. In 1993, there were 

approximately 300 secondary processing facilities 

in Colorado, of which more than 200 were located 

along the Front Range. There were 60 to 70 facilities within Boulder, Weld, and Larimer Counties 

(NEOS 1993a).

The amount of wood residues produced annually by 41 of 176 secondary processing facilities 

in the Denver and Colorado Springs metropolitan 

areas is shown in table 3. Based on the survey 

conducted by NEOS (1993a), 77% of wood residues were deposited in landfills. Seventy percent 

of the respondents were interested in alternatives 

to landfill disposal.

A more recent study (Ward 2000) surveyed P&S 

processors along the Front Range of Colorado. 

From the data that was collected, the major forms 

of residues generated fell into eight categories:

• Sawdust

• Scrap

• Pole peelings

• Pallets

• Dunnage

• Fines

• Shavings and chips

• Firewood

Of these, table 4 reveals that the three most 

common forms of residue were sawdust (39%), 

scrap material (35%), and shavings/chips (16%).

The means by which these residues were further 

utilized or disposed of fell into seven categories:

• Landfilled (MSW)

• Horse bedding

• Used on site

• Fuelwood

Table 3—Secondary wood processing residues produced by 

Colorado processors surveyed by NEOS (1993a).

Residue Bone dry tons

Sawdust 211

Chips 12

Shavings 174

Sander dust 1393

Solid wood 215
USDA Forest Service RMRS-RP-50. 2004 7

of red zone are located along the Front Range. 

In addition, approximately 17.3 million acres of 

forests are considered moderate to high risk in 

Colorado.

The Colorado State Forest Service conducted 

fuel break thinning projects at three sites located in the vicinity of Cheesman Reservoir in 

the spring of 2000. The purpose of these projects was to reduce fire hazard and restore forest 

health and diversity. Lynch (2000) completed an 

economic analysis that evaluated the costs associated with removal and transportation of logs to 

the Louisiana Pacific oriented strandboard mill 

located in Olathe, Colorado. In addition to cost 

data, information related to the quantity of trees 

cut, diameter, number of logs skidded and loaded, 

and truckload weights was recorded. Almost 160 

acres were treated on the three sites with an average density of 58.9 trees per acre. Overall, 9,545 

trees were cut and 2,113 green-tons of logs were 

removed. An average of 13.3 tons of trees was removed per acre. Treatment of each site resulted in 

a financial loss to the logger, which totaled about 

$77,870. The average loss per ton of green logs removed was around $37.

Based on this study, it was estimated that forest restoration projects along the Front Range of 

Colorado could conservatively yield 9 to 15 green 

tons per acre. The majority of the trees removed 

from each site, 88% to 90%, were classified as 

small diameter (less than 12 inches diameter at 

breast height), which limits how merchantable they 

would be in wood processing markets. Considering 

the acreage involved along the Front Range, there 

is an enormous amount of wood that could potentially be removed. The NEOS Corporation (1993b) 

estimated that Larimer County forests have over 

1.4 million tons of wood that could be removed during fuel hazard reduction and restoration projects. 

More recently, the National Fire Plan (USDI 2002) 

stated that 30,442 acres were treated in Colorado 

during 2001 as part of hazardous fuels reduction 

and forest restoration efforts. The precise amount 

of forest biomass generated from these projects is 

difficult to estimate because a high percentage of it 

was left in the forest loped and scattered, chipped 

and blown on the forest floor, or piled and burned. 

However, based on conservative yields (9 to 15 

green-tons per acre) from restoration projects, the 

amount of forest biomass that could have been removed and utilized was in the range of 270,000 

to 460,000 green tons. Because this was for the 

entire state, the potential amount of biomass 

generated along the Front Range in 2001 was considerably less.

In addition, there is a pine beetle epidemic underway in ponderosa pine forests of Colorado, 

including the Front Range. Beetle-killed trees removed to promote forest health could be utilized 

for fuel. In 1999, Larimer County had 4,000 to 

5,000 beetle-killed pine trees (CSFS 2000).

Potential for Utilizing Wood Wastes and 

Residues

Even though a substantial wood supply exists, 

there are many factors that could interfere with 

utilizing it. Costs associated with procurement can 

be a limiting factor. This would include recovery 

(sorting), transportation, drying, and processing 

(chipping and/or grinding) costs. For significant 

amounts of wood to be utilized, procurement costs 

will have to be much less than the current price of 

coal, which is $20 to $25 per ton.

MSW debris is commingled, making it difficult 

and expensive to sort. To maximize wood recovery 

from the MSW, it might be most efficient to have 

wood sorted by households for curbside collection, 

similar to the way existing recycling programs 

are implemented. This would minimize the effort 

and cost to the county associated with sorting. 

A curbside wood-sorting program would increase 

the recoverability of wood that otherwise is typically deposited in landfills. If sorting is done at the 

landfill, the only realistic means of covering costs 

associated with sorting would be to charge appropriate tipping fees that would pay for separation.

Separated construction woody material is clean 

and would be suitable for fuel and other alternative uses. However, there are possible limitations 

and barriers that could impede proper sorting. 

Construction debris often consists of commingled 

wood and non-wood products (shingles, caulk, 

plastic tubing, and other miscellaneous contaminants). Other limitations that were cited in the City 

of Fort Collins (2000) study stated that size of site 

and method of cleanup also significantly contributed to how effective wood sorting efforts would be. 

Generally, the larger the site is (longer distance to 

sorting bins), the greater the contamination.

To encourage future efforts and progress in maintaining successful recycling programs, it would be 

optimal for the costs of recycling woody materials to 

be less than standard trash disposal. As previously 

stated, most of the companies involved in the Fort 

Collins pilot project did experience lower trash disposal fees. However, time and labor costs increased 

because materials needed to be sorted. To create 

more incentive and keep costs lower for construction companies, consideration is being given to 

reduced tipping fees or directly subsidizing efforts.

With regard to P&S wood processors, they 

generally support the concept of recovering and 

utilizing their wood residues. The main factors that 
8 USDA Forest Service RMRS-RP-50. 2004

interfere with diversion and recovery of wood residues are the costs. It is often easier for processors 

to dispose of materials rather than take the time 

to sort. There are also some processing facilities 

that sell their residues. The majority breakeven 

or incur losses, but a few make a profit (generally 

small). If costs of diversion are less than or comparable to current disposal methods, there will be 

more willingness to utilize residue productively. 

The cost of disposal and/or the revenues generated from selling wood residues varies depending 

on the type and quantity generated.

To utilize wood residues, the primary requirement 

is that they be clean and free of foreign materials 

such as steel and other contaminants. Therefore, 

some consideration might be given to developing 

collection methods that minimize the commingling 

of wood with other materials that might be unacceptable for combustion or other uses.

While some research of forest residue generation in the region is available (NEOS 1993b; Lynch 

1999), specific data on residue availability and 

costs associated with collecting forest residues are 

harder to come by. Significant quantities of forest 

residues could be available, but the costs associated with collecting these residues create the 

greatest barrier to utilizing this resource.

For the three fuel mitigation (forest restoration thinning) projects near Cheesman Reservoir 

in Colorado assessed by Lynch (2000), work was 

completed at an average loss to the logger of about 

$491 per acre. This was primarily due to high costs 

associated with removing small diameter trees, the 

poor quality of trees removed, and the average hauling distance of 256 miles to the nearest processing 

facility that would take them. It has become evident that even though tree densities are high and 

thinning will be necessary to improve forest health 

conditions and reduce fire hazards, it is more than 

likely that without subsidies, thinning will not occur 

on public forestlands unless higher value products 

can be produced from small diameter material.

Forest residues are expensive to collect. In a test 

conducted at the Holcim (formerly Holnam) Cement 

Plant north of Fort Collins, 98 tons of forest residues were delivered to the plant at a cost of $35 

per green-ton for the wood and an additional $10 

per ton to chip logs into a useable form (Mackes 

and Lightburn 2002). Costs could be reduced if an 

operation were set up specifically to supply wood 

chips for energy. However, the concept of utilizing 

conventional logging to supply wood to these facilities is not promising. Mobile collection sites where 

private landowners can deposit wood residues 

have been established in Larimer County and other Front Range counties. These sites could provide 

a solution for collecting wood at a low cost. Efforts 

need to be directed at educating private landowners so they will properly manage their forested 

acres and provide for defensible space around 

structures, utilizing these sites to dispose of the 

wood removed from their property.

Conclusion

Wood residues and wastes could be used as a 

fuel source. Sources of this material include MSW, 

C&D, P&S, and forest residues. Significant quantities of wood are being deposited into landfills, 

even though opportunities and markets exist for 

utilizing woody residues. The majority of this wood 

wastes (excluding paper) comes from construction 

and urban forest residue. Although these residues 

tend to be cleaner and better sorted, a program 

is needed to separate C&D materials and urban 

forest residues from the MSW stream going into 

landfills. This can be accomplished by sorting at 

curbside, construction sites, or landfills, or by 

establishing specific areas designated to receive 

wood wastes and residues.

Primary and secondary wood processors could 

potentially supply significant quantities of wood as 

well. Processors appeared willing to consider alternative wood disposal methods such as using them 

for fuel given that any costs associated with utilizing 

the material were equal to or ideally less than current 

methods of disposal/end use. In some cases, it may 

be necessary to purchase higher quality residues 

with specified form and cleanliness. This ultimately 

depends on the desired end use for the residue.

Although significant quantities of forest residues could be generated and available from 

thinning projects, in the absence of government 

subsidies, forest residues may be too expensive. 

The economic feasibility and functionality of sites 

established to receive forest residues have to be 

assessed further to determine if they are a viable 

collection alternative.

Many types of wood wastes and residues can be 

recovered for use. Uses for this material aren’t limited to fuel alternatives. Further analyses should 

also evaluate the potential for utilizing wood residues that are currently sent to landfills in other 

commercial uses, such as landscape mulch, animal bedding, and compost. However, given the 

current market conditions, it will take willingness 

on the part of the public and wood processors in 

the region to recover wood destined for landfills 

and utilize it for fuel and/or other products that 

benefit society.
USDA Forest Service RMRS-RP-50. 2004 

9

References

City of Fort Collins. 2000. Construction wood debris 

recycling pilot project report. Fort Collins, CO: 

Natural Resources Department.

CSFS. 2000. Mountain pine beetle. Colorado Forestry 

Newsletter, Fort Collins District: Colorado State 

Forest Service. 8(1): 4; February.

Henderson, Janelle. 2000. Personal communication. 

March 30. Director, Natural Resources Department, 

City of Fort Collins, CO.

Lynch, Dennis L. 1999. Fort Collins vicinity preliminary 

wood biomass report. Fort Collins, CO: Department of 

Forest Sciences, Colorado State University.

Lynch, Dennis L. 2000. Summary report: Forest 

restoration thinning project on Denver Water Board 

property at Cheesman Reservoir and Trumbull sites. 

Fort Collins, CO: Department of Forest Sciences, 

Colorado State University.

McKeever, David B. 1998. Wood residual quantities in 

the United States. BioCycle. 39(1): 65-68.

Mackes, Kurt H.; Lightburn, Charles R. 2003. Evaluating 

the use of wood as an alternative fuel for making 

cement. Forest Products Journal. 53(4): 42-47.

National Association of Home Builders. 2001. Annual 

building permit activity 1998 – 2000. <http:/

/www.nahb.com/facts/permits/permits_yrly_

comparison.htm>

NEOS Corporation. 1993a. Colorado wood residues 

resource assessment: results of a survey of the 

metropolitan Denver and Colorado Springs secondary 

wood products manufactures: Final report. Denver, 

CO: State of Colorado, Office of Energy Conservation.

NEOS Corporation. 1993b. Wood pellet manufacturing 

in Colorado: An opportunity analysis. Denver, CO: 

State of Colorado, Office of Energy Conservation.

U.S. Census Bureau. 2004. Colorado quickfacts: Housing 

units authorized by building permits, 2002. <http://

quickfacts.census.gov/qfd/states/08000.html>

U.S. Department of Energy, Energy Information 

Administration. 1999. Primary Energy Consumed in 

Colorado by Source, 1999. <http://www/eia.doe.gov/

emeu/sep/co/pecg.html>

U.S. Department of the Interior. 2002. National Fire 

Plan: Colorado state summary from Department of 

the Interior. 2001. <http://www.fireplan.gov/

statebystate/Colorado1.cfm>

U.S. Environmental Protection Agency, Office of 

Solid Waste. 1998. Characterization of buildingrelated construction and demolition debris. 

EPA530-R-98-010. <http://www.epa.gov/epaoswer/

hazwaste/sqg/c&d-rpt.pdf>

U.S. Environmental Protection Agency, Office of Solid 

Waste. 2003. Municipal Solid Waste in the United 

States: 2001 facts and figures. EPA530-R-03-011. 

<http://www.epa.gov/epaoswer/non-hw/muncpl/

pubs/msw2001.pdf>

Ward, Julie E. 2000. Phone survey of primary and 

secondary wood processors along the Front Range 

of Colorado. Fort Collins, CO: Colorado State Forest 

Service.
The U.S. Department of Agriculture (USDA) prohibits discrimination 

in all its programs and activities on the basis of race, color, national 

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programs.) Persons with disabilities who require alternative means for 

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The Rocky Mountain Research Station develops scientific 

information and technology to improve management, protection, 

and use of the forests and rangelands. Research is designed to 

meet the needs of the National Forest managers, Federal and 

State agencies, public and private organizations, academic 

institutions, industry, and individuals.

Studies accelerate solutions to problems involving 

ecosystems, range, forests, water, recreation, fire, resource 

inventory, land reclamation, community sustainability, forest 

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Research Locations

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