ATTACHMENT A TO THE STAFF REPORT 

SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

Technology Assessment for: 

PROPOSED RULE 1133: EMISSION REDUCTIONS FROM COMPOSTING 

 AND RELATED OPERATIONS 

March 22, 2002 

Deputy Executive Officer 

Planning, Rule Development and Area Sources 

Elaine Chang, DrPH 

Assistant Deputy Executive Officer 

Planning, Rule Development and Area Sources 

Laki Tisopulos, Ph.D., P.E. 

Planning and Rules Manager 

Planning, Rule Development and Area Sources 

Alene Taber, AICP 

Authors: Shah Dabirian, Ph.D. Air Quality Specialist 

 Tuyet-Le Pham Transportation Specialist 

Barbara Radlein Air Quality Specialist 

Ricardo A. Rivera Air Quality Specialist 

Reviewed by: Frances Keeler Senior Deputy District Counsel 

 Julia Lester, Ph.D. Program Supervisor 

Contributors: Fred Braganza Air Quality Inspector II 

Mike Garibay Air Quality Engineer II 

Rick Gluck Air Quality Inspector II 

John Higuchi Source Testing & Monitoring Manager 

Lori Inga Sr. Office Assistant 

Dave Jones Air Quality Analysis & Compliance Supervisor 

Rodney Millican Senior Air Quality Engineer 

Arun Roychowdhury Supervising Air Quality Engineer 

Dan Russell Air Quality Specialist 

Kathy C. Stevens Air Quality Specialist 

Rich Tambara Supervising Air Quality Inspector 
 

SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

GOVERNING BOARD 

CHAIR: NORMA J. GLOVER 

 Councilmember, City of Newport Beach 

 Cities Representative, Orange County 

VICE CHAIR: WILLIAM A. BURKE, Ed.D. 

 Speaker of the Assembly Appointee 

MEMBERS: 

 MICHAEL D. ANTONOVICH 

 Supervisor, Fifth District 

 Los Angeles County Representative 

 HAL BERNSON 

 Councilmember, City of Los Angeles 

 Cities Representative, Los Angeles County, Western Region 

 JANE CARNEY 

 Senate Rules Committee Appointee 

 JAMES W. SILVA 

 Supervisor, Second District 

 Orange County Representative 

 BEATRICE J.S. LAPISTO-KIRTLEY 

 Councilmember, City of Bradbury 

 Cities Representative, Los Angeles County, Eastern Region 

 RONALD O. LOVERIDGE 

 Mayor, City of Riverside 

 Cities Representative, Riverside County 

 JON D. MIKELS 

 Supervisor, Second District 

 San Bernardino County Representative 

 LEONARD PAULITZ 

 Mayor Pro Tem, City of Montclair 

 Cities Representative, San Bernardino County 

 CYNTHIA VERDUGO-PERALTA 

 Governor's Appointee 

 S. ROY WILSON, Ed.D. 

 Supervisor, Fourth District 

 Riverside County Representative 

EXECUTIVE OFFICER: 

BARRY R. WALLERSTEIN, D.Env. 
LIST OF ACRONYMS AND ABBREVIATIONS

AB Assembly Bill 

AQMD South Coast Air Quality Management District 

AQMP Air Quality Management Plan 

BACT Best Available Control Technology 

CARB California Air Resources Board 

CEQA California Environmental Quality Act 

CIWMB California Integrated Waste Management Board 

EPA U.S. Environmental Protection Agency 

LEA Local Enforcement Agency 

NH3 Ammonia 

NPDES National Pollutant Discharge Elimination System 

PM10 Particulate Matter with Aerodynamic Diameter less than 10 Microns 

RWQCB Regional Water Quality Control Board 

RCRA Resource Conservation and Recovery Act 

ROG Reactive Organic Gas 

SIC Standard Industrial Classification 

SIP State Implementation Plan 

VOC Volatile Organic Compound 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 i March 2002 

TABLE OF CONTENTS 

TABLE OF CONTENTS .................................................................................................. i 

TABLES OF TABLES .................................................................................................... iii 

TABLE OF FIGURES................................................................................................... iii 

EXECUTIVE SUMMARY ........................................................................................ES-1

CHAPTER I – BACKGROUND INFORMATION 

 Air Quality ........................................................................................................... 1-1 

 Composting Process............................................................................................. 1-3 

 Chipping and Grinding Activities........................................................................ 1-8 

 Overview of Current Regulatory Requirements .................................................. 1-9 

 Other Issues Facing the Composting Industry................................................... 1-14 

 Necessity for Proposed Rule 1133..................................................................... 1-20 

CHAPTER II – INDUSTRY PROFILE AND EMISSIONS 

 Industry Profile .................................................................................................... 2-1 

 Emissions Inventory............................................................................................. 2-2 

CHAPTER III – CONTROL TECHNOLOGY ASSESSMENT 

 Composting Methods........................................................................................... 3-1 

 Emission Control System..................................................................................... 3-4 

 Demonstrated Control Efficiencies...................................................................... 3-6 

 Chipping and Grinding Methods ......................................................................... 3-7 

CHAPTER IV - PROPOSED RULE 1133 

 Emission Reductions............................................................................................ 4-1 

 Cost-Effectiveness ............................................................................................... 4-5 

CHAPTER V - RECOMENDATIONS 

 AQMD Staff Recommendations.......................................................................... 5-1 

CHAPTER VI – OUTREACH, KEY ISSUES, AND RESPONSES 

 Public Outreach.................................................................................................... 6-1 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 ii March 2002 

REFERENCES ..........................................................................................................Ref. 1 

APPENDIX A - List of Operational ASP Facilities In the U.S................ Appendix-A-1 

APPENDIX B – List of Operational In-Vessel Composting 

 Facilities In the U.S........................................................ Appendix-B-1 

APPENDIX C – Biofilters In Operation At Composting 

 Facilities In the United States ...................................... Appendix-C-1 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 iii March 2002 

TABLE OF TABLES 

Table 1-1 Solid Waste Tipping Fee Survey of California 1-9 

Table 1-2 2000-2001 Public Complaints/AQMD Enforcement Actions 

On Composting and Chipping and Grinding Operations 

1-14 

Table 1-3 Types of Organics Contributing to Waste Stream 1-16 

Table 1-4 Top Ten Materials in Waste Stream 1-16 

Table 1-5 CIWMB Identified Examples of Programs to Divert 

Greenwaste 

1-17 

Table 1-6 CIWMB Statewide ADC Analysis (tons/year) 1-19 

Table 2-1 Composting Industry and Related Operations 2-1 

Table 2-2 Composting Facilities by County 2-2 

Table 2-3 Windrow Emissions Factors 2-3 

Table 2-4 Composite Emission Rates (Early Fall Test) 2-5 

Table 2-5 Composite Emission Factors 2-6 

Table 2-6 Emission Factors for Greenwaste Composting 2-6 

Table 2-7 Emission Rates 2-6 

Table 2-8 Emission Factors 2-7 

Table 2-9 Emission Factors for Greenwaste-Composting 2-7 

Table 2-10 Weighted-Average Emission Factors for Greenwaste 

Composting 

2-7 

Table 2-11 Emissions Inventory 2-8 

Table 3-1 Optimal Composting Conditions 3-1 

Table 3-2 Composting Methods, Capture and Control Efficiencies 3-6 

Table 4-1 Co-Composting Scenarios 4-3 

Table 4-2 Greenwaste Scenarios 4-4 

Table 4-3 Number of Facilities by Sales and Employees 4-6 

Table 4-4 Co-Composting Annualized Cost and Cost Effectiveness by 

Scenario 

4-8 

Table 4-5 Greenwaste-Only Annualized Cost and Cost-effectiveness by 

Scenario 

4-9 

Table 4-6 Potential Cost Impacts of the Proposed Rule on Selected CoComposting Facilities 

4-11 

Table 4-7 Potential Cost Impacts of the Proposed Rule on Selected 

Greenwaste-only Facilities 

4-11 

TABLE OF FIGURES

Figure 1-1 Phases During Composting 1-5 

 

Figure 2-1 Methane Emissions vs. Time 2-4 

Figure 2-2 Ammonia Emissions vs. Time 2-4 
 

EXECUTIVE SUMMARY 

 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 ES - 1 March 2002 

INTRODUCTION 

9 This chapter provides an Executive Summary 

EXECUTIVE SUMMARY 

Background 

The South Coast Air Quality Management District (AQMD) is the local agency 

responsible for air quality assessment and improvement in the four-county area that 

includes Orange, the non-desert portions of Los Angeles and San Bernardino 

Counties, and most of Riverside County. In order to accomplish its mandate, AQMD 

is required to adopt and implement an Air Quality Management Plan (AQMP) that 

identifies the control strategies to achieve federal ambient air quality standards and 

demonstrate compliance with the state and federal clean air acts. The South Coast 

Air Basin (Basin) is a serious non-attainment area for PM10 (particulate matter less 

than 10 microns) and must attain the standard by 2006. The Basin is the only extreme 

ozone non-attainment area and must attain the standard by 2010. Ammonia is a 

precursor of PM10, particularly aerosol ammonium nitrate and ammonium sulfate. 

Volatile Organic Compounds (VOCs) are precursors to ozone. As shown in this 

report, composting of greenwaste only produces significant VOC emissions and 

appreciable ammonia emissions. Composting of sewage sludge and manure produces 

significant ammonia emissions in localized areas, as well as VOC emissions. 

The 1997 AQMP and the 1999 Amendments to the 1997 Ozone State Implementation 

Plan (SIP) for the South Coast Air Basin included Control Measure WST-02 – 

Emission Reductions from Composting. This technology assessment report provides 

information developed as part of the rule development efforts undertaken to date by 

AQMD staff to implement Control Measure WST-02. 

This report provides background information and rule development recommendations 

that will be submitted to the AQMD Governing Board at the April 5, 2001 PreHearing for Proposed Rule 1133 – Emissions Reductions from Composting and 

Related Operations. 

Industry Profile 

The composting and related operations industry within the AQMD’s jurisdiction 

includes 277 facilities categorized as follows: co-composting facilities; greenwaste 

only composting facilities; chipping and grinding facilities; and, exempt facilities. 

Co-composting facilities use putrescible materials, such as, wastewater sludge, 

manure, or food waste in combination with greenwaste as their process feedstock. 

Greenwaste composting facilities are composting facilities that only use greenwaste 

as process feedstock. Chipping and grinding facilities are facilities dedicated to the 

size reduction of greenwaste for uses such as alternative daily cover, biomass fuel, 

mulch, soil amendments, or composting feedstock. Finally; exempt facilities are 

facilities that are part of this industry but are likely to be exempt from regulation 

under Proposed Rule 1133. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 March 2002 

Emissions Inventory 

The baseline emissions inventory estimated for the industry is 4.7 and 6.8 tons per 

day for ammonia and VOC, respectively. The co-composting emissions inventory is 

estimated at 3.7 and 2.2 tons per day of ammonia and VOC, respectively. The 

greenwaste composting emissions inventory is estimated at 1.0 and 4.4 tons per day 

of ammonia and VOC, respectively. 

The largest co-composting facilities are estimated each to emit 100 to 300 tons per 

year of VOC and 150 to 500 tons per year of ammonia. The largest greenwaste 

composting facilities are estimated each to emit 250 to 600 tons per year of VOC 

emissions, which would rank them among the largest VOC sources in the Basin. 

The baseline emission inventory is based on source tests and emissions studies 

conducted by AQMD staff. The CIWMB subsequently conducted a series of source 

tests at greenwaste processing and composting facilities in December of 2001. 

Although the final results have not been completely reviewed by AQMD staff in time 

to be included in this report, AQMD staff will incorporate those test results to the 

greewaste composting emissions analysis and report the revised analysis to 

stakeholders as soon as possible. 

Technical Assessment 

AQMD staff has conducted a technology assessment of the composting and related 

operations industry. The technology assessment reviews composting processes 

available to industry including the following: windrow, aerated static piles, and invessel. The analysis also evaluated ASP systems and enclosures in combination with 

bio-filtration systems. Based on this analysis, AQMD staff demonstrated that there 

are technological options that will significantly reduce emissions from the 

composting and related operations industry. 

Control Options and Socioeconomic Analysis 

AQMD staff developed three control scenarios to evaluate the potential emission 

reductions and cost of controlling co-composting and greenwaste composting. 

Scenario one assumes the enclosure of the active and curing parts of the composting 

process, the use of an ASP or in-vessel system, and venting of emissions to control 

equipment (i.e., biofilter). Scenario two assumes enclosure of the active phase of the 

process and the use of an ASP or in-vessel system with emissions vented to control 

equipment. For the curing phase of the process, scenario two has a variation for cocomposting and greenwaste composting. For co-composting, scenario two assumes 

the use of a negative-pressure ASP system with emissions vented to controls (no 

enclosure). For the greenwaste composting, scenario two assumes no controls for the 

curing phase of the process. Finally, scenario three assumes the use of a negativepressure ASP system for both the active and curing phases of the process with 

emissions vented to control equipment (no enclosures). 

As part of the cost analysis, AQMD staff has analyzed cost-effectiveness and 

compliance affordability. In general, while the control options for the co-composting 

sector of the industry are seen as feasible and effective, they are costly. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 March 2002 

Relative to co-composting, the control options for the greenwaste composting sector 

of the industry are more cost effective. However, the affordability analysis, as 

presented in Chapter IV, demonstrates that the cost impact for this industry would be 

substantial. 

Recommendation 

Based on information in this report, AQMD staff is recommending that AQMP 

Control Measure WST-2 – Emission Reductions from Composting, be implemented 

in two phases. The first phase would consist of an adoption of a fact-finding rule that 

would have the elements listed below. The first phase would also include control 

requirements for new co-composting facilities with total throughput design capacity 

of 100,000 tons per year. The second phase would consider composting control 

technologies for new and existing facilities based on the results of additional technical 

work described below. 

Requirements for Co-Composting

As described in this report, co-composting facilities are major sources of VOC and 

ammonia emissions (e.g., a 100,000 ton/year total throughput facility has annual 

emissions of 89 tons/year VOC and 147 tons/year ammonia). Based on local 

community concerns and industry studies, siting of large co-composing facilities in 

urban areas now requires active consideration of enclosed and controlled facilities to 

address public health and nuisance concerns. Enclosed ASP or in-vessel systems 

with control equipment, while feasible and effective at significantly reducing 

emissions, are costly. Therefore, AQMD staff recommendations are as follows: 

Existing and new Co-Composting Facilities 

• One-time registration with AQMD; 

• Annual reporting requirements; 

• PM10 controls to prevent visible PM10 emissions over the property line 

during operations and from compost piles; and, 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions. 

New Co-Composting Facilities with a Design Capacity > 100,000 tpy 

• Scenario II control requirements for new facilities with total throughput 

designed capacity of 100,000 tons per year; 

9 Enclosure and ASP for the active phase of the process with emissions 

vented to a bio-filtration system; 

9 Open ASP for the curing phase of the process with emission vented to 

a bio-filtration system; 

Greenwaste Composting

As described in this report, the greenwaste industry represents a significant source of 

VOC emissions. Control options, in general, are more cost-effective; however, our 

affordability analysis indicates that these controls may have adverse impacts on the 

industry. As a result, the staff is proposing minimal requirements on greenwaste 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 March 2002 

composting at this time. The requirements are intended to primarily track operations 

and emissions, so that emission reductions can be claimed if specific controls are 

implemented in the future. The following summarizes the proposed requirements for 

existing and new greenwaste composting operations. 

• One-time registration 

• Annual reporting requirements 

• PM10 controls to prevent visible PM10 emissions over the property line 

during operations and from compost piles; and, 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions. 

In light of the fact that there are feasible control options for this industry that are not 

yet affordable, AQMD staff is recommending that, through the District’s Legislative 

Committee, special funding from the state legislature be sought to implement state-ofthe-art composting methods, including but not limited to, enclosed ASP. AQMD 

staff will work with the CIWMB and CARB to seek additional funding and/or make 

existing funding directed more towards air quality spending. 

The administrative requirements for the proposed rule are detailed in Chapter V of 

this report. These requirements would include a one-time registration with AQMD 

and annual reporting. 

Chipping and Grinding Operations

Chipping and grinding operations can be sources of PM10 and VOCs. PM10 results 

from the chipping, grinding and screening of green materials. It can also result when 

high winds entrain material from processed material piles. Chipped and ground 

material that is not removed or further processed can decompose anaerobically, 

resulting in odors and higher levels of VOCs. To address these issues, AQMD staff is 

proposing the following requirements: 

• One-time registration; 

• PM10 controls to prevent visible PM10 emissions over the property line 

during operations and from processed material piles; 

• Holding time restrictions on curbside fines and processed green material piles; 

and 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions 

As part of this proposal, AQMD staff is also recommending that the Governing Board 

direct staff to continue the rule development efforts with the following objectives: 1) 

continue to evaluate ongoing emissions studies and refine the emissions inventory for 

the industry; 2) refine the socioeconomic analysis; 3) work with the Integrated Waste 

Management Board, sanitation districts and other pertinent agencies to identify 

sources of funding to help reduce the cost of compliance for the greenwaste 

composting sector of the composing industry. Finally, AQMD staff is further 

recommending that a Technical Advisory Committee be formed and serve as a forum 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 5 March 2002 

to address technical issues related to Proposed Rule 1133. There will be annual status 

reports to the AQMD Stationary Source Committee on facility emissions and the 

feasibility of implementing additional cost-effective controls. 
CHAPTER I 

 

BACKGROUND INFORMATION 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 1 March 2002 

INTRODUCTION 

This chapter discusses the following: 

9 Air quality; 

9 Composting Process; 

9 Chipping and Grinding Activities; 

9 Overview of Current Regulatory Requirements; 

9 Other Issues Facing the Composting Industry; and, 

9 Necessity for Proposed Rule 1133. 

AIR QUALITY 

The AQMD is the local government agency responsible for air quality assessment and 

improvement in Orange county, the non-desert portions of Los Angeles and San 

Bernardino counties, and most of Riverside county. AQMD jurisdictional boundaries 

include all of the South Coast Air Basin (SCAB) and portions of the Salton Sea Air 

Basin (SSAB). AQMD air monitoring indicates that these air basins exceed State and 

federal health-based air quality standards for PM10 (small particulate matter less than 

10 microns in diameter) and ozone. Accordingly, the U.S. EPA has designated both 

the SCAB and the SSAB as serious non-attainment areas for PM10. The designation 

for ozone is extreme and severe-171

 for SCAB and SSAB, receptively. Under the 

federal Clean Air Act, the AQMD is required to attain the PM10 standards for both of 

these air basins by 2006. For ozone, the AQMD is required to attain the ozone 

standards by 2010 and 2007 for SCAB and SSAB, respectively. 

In order to attain healthful air, federal and state laws require the AQMD to adopt an 

Air Quality Management Plan (AQMP) that identifies a control strategy to 

demonstrate compliance with federal ambient air quality standards and expeditious 

progress toward state air quality standards.2 To address these state and federal 

mandates, the 1997 AQMP and 1999 Amendments to the 1997 Ozone State 

Implementation Plan for the SCAB included Control Measure WST-02 – Emission 

Reductions from Composting. These air plans identified composting as a source of 

ammonia, PM10, and VOC emissions. As such, Control Measure WST-02 calls for 

the development of viable controls to reduce the emissions from this industry by 

2001. Proposed Rule 1133 – Emission Reductions from Composting Operations and 

Related Operations, has been developed to implement Control Measure WST-02. 

Following is a brief description of the health and environmental concerns with air 

contaminants emitted from composting and related operations that contribute to the 

formation of PM10 and ozone. Bioaerosols, which are organisms (including 

aspergillus fumigatus, endoctoxin, and organic dust) dispersed through the air that 

can affect human health, are not addressed in this report. Finally, since U.S. EPA 

regulates pathogens, which are bacteria, viruses, and parasites found in most compost 

 

1 Name given to a severe ozone non-attainments are with a 1988 ozone design value between 

0.19 and 0.28. The attainment date is 17 years (instead of 15 years) after the date of enactment 

of the Clean Air Act Amendments of 1990. 

2

 California Health and Safety Code Section 40460(a).
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 2 March 2002

feedstocks, and the regulations are considered effective in pathogen destruction by 

experts in the field, this issue is also not addressed in this technology assessment. 

Particulate Matter (PM10) 

Composting and related operations (i.e., chipping and grinding) are sources of direct 

PM10 and ammonia, which is a PM10 precursor. Ammonia in the atmosphere reacts 

with nitric acid and sulfuric acid to produce nitrate and sulfate particles, a constituent 

of PM10. 

PM10 is generated when composting piles are turned, moved, and from wind 

entrainment of static uncovered piles. Associated activities like chipping and 

grinding also produces PM10 emissions when the wood and greenwaste are 

mechanically ground and shredded. Biological degradation (or decomposition) of 

organic materials (i.e., yard waste, manure, sewer sludge, etc.) that occurs during 

composting and when chipped and ground material begins to rot produces ammonia. 

Ammonia is produced in both aerobic (in the presence of oxygen) and anaerobic (in 

the absence of oxygen) environments. Composting is an aerobic process but can 

become anaerobic when for example, a pile is built incorrectly, the pile gets too little 

oxygen, the temperature is too high, or there is too little or too much moisture. 

Chipped and ground material that is left unmanaged likewise begins to decompose 

and produce ammonia emissions for the same reasons as composting. 

PM10 is a public health concern since particles less than 10 microns can be deposited 

in, and can damage, the airways of the lower respiratory tract and the gas-exchange 

portions of the lung. The adverse health effects of particulates, especially PM10, are 

well documented. Various health studies have linked PM10 emissions to increased 

respiratory infections, more severe asthma, declines in pulmonary function, and 

shortened life spans. Specifically, recent studies indicate that the current ambient 

levels of PM10 (30 to 150 μg/m3

) experienced in many different communities in the 

United States are associated with increases in daily cardio-respiratory mortality and in 

total mortality, excluding accidental and suicide deaths. Increases in ambient PM10 

levels have also been shown to result in increases in acute respiratory hospital 

admissions, school absences in children, and increases in the use of medications in 

children and adults with asthma. 

Ozone 

VOCs are produced during the anaerobic (in the absence of oxygen) decomposition of 

organic material. Decomposition occurs when chipped and ground material is 

composted or when the material is left in an unmanaged state and begins to rot. 

There are no state or national ambient air quality standards for VOCs because they 

are not classified as criteria pollutants. VOCs are regulated, however, because VOCs 

contribute to the formation of ozone and are transformed into organic aerosols in the 

atmosphere, contributing to higher PM10 and lower visibility levels. Ozone is formed 

in the atmosphere through a photochemical reaction of VOC and NOx. 

Ozone is a deep lung irritant, causing the lung passages to become inflamed and 

swollen. Exposure to ozone produces alterations in respiration, the most 

characteristic of which is shallow, rapid breathing and a decrease in pulmonary 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 3 March 2002

performance. Ozone reduces the respiratory system's ability to fight infection and to 

remove foreign particles. People who suffer from respiratory diseases such as 

asthma, emphysema, and chronic bronchitis are more sensitive to ozone's effects. 

Early studies suggested that long-term exposure to ozone results in adverse effects on 

morphology and function of the lung and acceleration of lung-tumor formation and 

aging. Ozone exposure also increases the sensitivity of the lung to 

bronchoconstrictive agents such as histamine, acetylcholine, and allergens. 

COMPOSTING PROCESS 

Composting is a biological process where organic materials (i.e., leaves and grass, 

yard trimmings, agricultural crop residues, etc.) are decomposed by microorganisms 

to create a soil-like material called compost. While decomposition occurs naturally 

anywhere plants grow, the process has also been industrialized whereby green and 

wood wastes are mechanically ground and shredded accelerate and control the 

decomposition process. 

Sometimes the green and wood waste is mixed with putrescible wastes (i.e., manure, 

horse shavings, food waste, sewer sludge, etc.). In this region, with the exception of 

three facilities, the material is moved with front-end loaders into long piles called 

windrows. The windrows are then mechanically turned generally with front-end 

loaders to increase aeration and provide oxygen to facilitate the decomposition 

process. The temperature and moisture are monitored to optimize and hasten 

decomposition. After two to four months in the windrows, the material becomes 

compost. 

Composting is an important component of the solid waste industry. It provides 

resource conservation through source reduction, recycling, and reuse. However, as 

with other industrial processes, composting produces air emissions that are currently 

uncontrolled. In terms of air quality, composting is an exothermic process that 

releases carbon dioxide, water vapor, and other organic and inorganic gases such as 

ammonia, methane, VOCs, amines, and sulfides. The emissions impacts of 

composting are presented in the emission inventory section of this report. 

From an industrial perspective, composting is a three-stage process that begins as 

soon as appropriate materials are combined and piled together. The initial stage of 

the process is referred to as active composting followed by curing or finishing, and 

storage and/or processing of composted products. 

During the composting process microorganisms such as bacteria, fungi, and 

actinomycetes, consume oxygen while feeding on organic material such as 

wood/greenwaste, food-waste, livestock manure, sewer sludge (the semisolid residue 

of domestic sewage treatment processes) and other putrescible materials. The 

microbial activity results in the decay of the initial mixture and at the completion of 

the composting cycle wastes are transformed into a stable, pathogen-free composted 

material. 

The microorganisms that contribute to the composting process contain both 

thermophilic and mesophilic species. Themophilic and mesophilic microorganisms 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 4 March 2002

are microorganisms that can sustain life under high (110-150 oF) and low (50–105 oF) 

temperatures, respectively. The type of microbial activity present can characterize 

the active and curing stages of the composting process. Active composting is where 

the thermophilic microorganisms’ population is the highest. This stage is 

characterized by high temperatures, high level of oxygen demand and high 

evaporation rates due to temperature. Conversely, the curing stage of the process is 

where the mesophilic microorganism population is the highest and the need for 

oxygen and the evaporation rates decreases. There is also a linkage between the 

microbial activity and the VOC emissions profile from composting operations. 

Specifically, emissions can be correlated to the activity of these microorganisms in 

that the emissions are generally higher during thermophilic temperatures and lower 

during mesophilic temperatures. Figure 1-1 illustrates the oxygen demand and 

microbial profile of the various composting stages. This figure can be used to 

illustrate the corresponding VOC emissions. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 5 March 2002

Figure 1-1 

PHASES DURING COMPOSTING

OXYGEN DEMAND RATE, * CARBON DIOXIDE EVOLUTION TEMPERATURE 

COMPOSTING CURING SCREENING 

TIME

THERMOPHILIC

MESOPHILIC COMPOST IS 

STABLE 

PHASES DURING COMPOSTING

This graphic was provided by Eliot Epstein, Ph.D. Chief 

Environmental Scientist, Tetra Tech, Inc. 

*VOC emissions are expected to follow the similar profile as 

oxygen demand. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 6 March 2002

As stated before, it is the ability to control the physical and chemical characteristics 

of the process that makes composting a viable industrial process. Following is a 

description of the main characteristics that are optimized in an industrial composting 

process. 

Carbon-to-Nitrogen ratio (C:N) represents the weight of decomposable carbon to the 

weight of total nitrogen in an organic material. Carbon and nitrogen are two 

fundamental elements for microbial activity. Microorganisms utilize carbon for 

energy and growth, and nitrogen for protein and reproduction. C:N ratio is significant 

to the composting process because insufficient nitrogen (higher ratio) will limit 

microbial growth, but excess nitrogen (lower ratio) will generate ammonia or other 

compounds that cause odors. For the best composting, the recommended C:N range 

from 25:1 to 40:1, and a ratio of 30:1 is ideal. C:N ratio can be adjusted by adding 

organic materials high in nitrogen such as grass, sewage sludge, or animal manure, or 

by adding materials high in carbon such as leaves. Using commercial fertilizer as 

nitrogen supplement is not recommended because it will modify salt concentration in 

the compost and impede microbial activity. 

Moisture content is the water portion of the material's total weight, expressed in a 

percentage. Moisture is an essential part of composting. It allows microorganisms to 

move about and transport nutrients, as well as provides the medium for chemical 

reactions. Insufficient moisture content will lead to microorganisms entering a 

dormant stage. Excessive moisture will limit air movement to and in the compost 

pile, causing an anaerobic decomposition that generates unpleasant odors. In 

addition, excessive moisture will also result in leachate. Since moisture content 

decreases as composting proceeds, a starting moisture content of 40% to 60% is 

recommended, and 50% to 60% is considered to be ideal. Usually, a mixture that 

feels moist, like a well-wrung sponge, indicates sufficient moisture. Moisture content 

can be adjusted either by adding water or moisture-rich organic materials, such as 

liquid sewage sludge, or by adding dry bulking agents such as leaves or wood chips. 

Oxygen is critical to composting, especially during the early stage when 

microorganisms rapidly metabolize and grow. Insufficient oxygen supply will slow 

down the composting process and lead to an anaerobic decomposition that generates 

obnoxious odors, and ammonia and VOC emissions. Excess oxygen (or air) will also 

lower the pile's temperature slowing down the composting rate. Oxygen 

concentration fluctuates in response to the microbial activity. Usually, at the 

beginning of the composting process, oxygen concentration within the pore spaces is 

identical to oxygen concentration in the air (about 15% to 20%). However, as the 

compost ages, the oxygen concentration decreases and carbon dioxide concentration 

increases. A 5% to 15% oxygen concentration must be maintained for fast, aerobic 

composting. Oxygen (or air) can be provided by mechanical turning or by forced 

aeration, where air is either drawn or forced through the compost pile. 

Temperature is an important aspect of composting since composting occurs within 

two temperatures ranges, known as mesophilic (50o

F to 105oF) and thermophilic 

(over 105o

F). Thermophilic temperatures are preferred because they promote rapid 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 7 March 2002

composting, and destroy pathogens, weed seeds, as well as fly larvae. However, 

extreme temperatures (above 160oF) will kill most of the active, important 

microorganisms. According to composting experts, temperatures in the range of 

110o

F to 150oF are best for composting. The U.S. EPA requires that a minimum 

temperature of 131o

F be maintained for several days to eliminate bacteria and 

pathogens. Usually, adding external heat is unnecessary because during the 

composting process, heat is generated by microorganisms and is accumulated due to 

the pile's self-insulation. To prevent the temperature from rising to an extreme level 

that creates a fire hazard, frequent aeration is necessary. 

pH value indicates the level of acid or base in the compost. pH value is critical to 

composting since it affects the nutrient and metabolism of the microorganisms. 

Microorganisms consume organic acid very quickly; however, the majority of them 

can not survive an extreme acidic environment (i.e., where the pH value is far less 

than 7). According to composting experts, optimum pH values range between 6.5 and 

8.0. Increasing the pH value by the addition of lime or other additives is not advised 

because of the potential ammonia loss. pH values above 8.5 encourage the 

conversion of nitrogen compounds to ammonia, creating an odor problem. pH value 

changes during the composting process, and it can be adjusted by aeration or through 

a natural process called carbonate buffering. Through the carbonate buffering 

process, carbon dioxide combines with water to produce carbonic acid that will lower 

the compost pH. As a result, the final compost product always has a stable, close to 

neutral pH value. 

Particle size affects the efficiency of the composting process. Generally, microbial 

activity occurs on the surface of the particles. Therefore, an increase in the surface 

area by using smaller particles will increase the rate of decomposition. However, 

smaller particles also reduce the porosity, which is a measurement of the air space 

within the composting mass. This can result in poor aeration and increased 

emissions. Good particle sizes range from 1/8 to 2 inches average diameter and can 

be achieved by chopping, shredding, mowing, or breaking up the materials. 

Pile structure, in particular the mixing of materials, size and shape are important to 

start off the composting process properly. The materials to be composted must be 

thoroughly blended to evenly distribute moisture, porosity, and C:N ratio. A compost 

pile must be well constructed to prevent rapid dissipation of heat and moisture, yet 

allow good air circulation. The pile should be at least 3 ft x 3 ft x 3ft (1 cubic yard) to 

keep sufficient heat, but not larger than 5 ft x 5 ft x any length so air can diffuse to the 

center of the pile. Some composting system use forced air or mechanical turning to 

compensate for larger size piles. 

Feedstock also affects the composting process. One of the most important aspects of 

feedstock is how it affects the C:N ratio of the compost pile overall. Some 

feedstocks, like grass clippings, digested sewer sludge and food waste are higher in 

nitrogen content, while tree limbs and wood scraps are lower in nitrogen content. As 

such, waste materials are blended to achieve an optimum C:N ratio and 

decomposition rate. For the purpose of this rule, the composting industry has been 

divided into two main categories based on feedstocks handled: co-composting and 
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Proposed Rule 1133 1 - 8 March 2002

greenwaste composting. Co-composting uses putrescible feedstock materials 

including, but limited to, sewer sludge, cow and horse manure, and food waste 

combined with bulking agents like greenwaste or wood chips. The feedstock comes 

from sewage treatment plants, dairies, horse stables, restaurants, etc. 

Greenwaste composting only uses greenwaste feedstock materials such as wood, 

leaves and related raw materials. The feedstock comes from landscape maintenance 

activities, construction sites, agriculture, curb side recycling programs, etc. One of 

the primary factors affecting greenwaste supply from curb side recycling programs is 

the level of contamination (i.e., mixing of yard waste with other trash). The level of 

contamination varies widely among curb side recycling programs and is influenced 

by the amount of public outreach, the containment method, and frequency of pick-up. 

Products Produced 

Composted products are used in many applications depending on the characteristics 

of the raw materials and the quality of the product produced. In general, high quality 

compost may be used in agriculture, horticulture, landscaping and home gardening. 

Composting facilities that use sewer sludge as a feedstock generally rate the quality 

of their compost as high. Medium quality compost can be used in applications such 

as erosion control and roadside landscaping. Low quality compost can be used as a 

landfill cover or in land reclamation projects. In southern California, most of the 

composting products are used in agricultural and horticultural operations. Smaller 

markets for composting products include municipal, Caltrans, local residents, etc. 

Most composting facilities make between one and five different composting products. 

Some compost facilities also provide specialized services including special product 

blending, spreading, bagging and delivery. 

CHIPPING AND GRINDING ACTIVITIES 

The chipping and grinding component of the composting and related operations 

industry include operations that are dedicated mainly to the mechanical size reduction 

of greenwaste. Mobile chippers and/or tub grinders are used to shred the green 

material. Sometimes the equipment is connected to screens and magnetic separators 

to produce certain end products and improve the quality of the end product. These 

operations chip and grind greenwaste such as tree trunks, residential and commercial 

landscaping, curbside green-waste recycling, and debris from construction sites. The 

chipped and ground material produced is then used as an alternative daily cover 

(ADC) at landfills, fuel in waste-to energy facilities, mulch, raw material for 

greenwaste composting, or bulking agents for co-composting operations. Chip and 

grind operations can be a stand-alone operation or a part of a composting facility. 

Business Structure 

Composting and chipping and grinding facilities generate income from two sources. 

First, these facilities charge haulers “tipping” fees when they drop off the raw 

feedstocks. Second, these facilities sell the final products (e.g., compost, fuel for 

waste-to-energy plants, mulch, etc.). Tipping fees vary across the state. Table 1-1 

provides a summary of tipping fees throughout California from a study sponsored by 

the CIWMB in 2000. The study indicates that southern California has lower tipping 

fees than northern California. 
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Proposed Rule 1133 1 - 9 March 2002

Table 1-1 

Solid Waste Tipping Fee Survey of California 

Region Average Tipping Fee (per ton) 

Northern $58.49 

Bay Area $47.73 

Central Coast $39.21 

Central Valley $35.79 

Southern (includes SCAB) $35.42 

In the SCAB, based on staff survey, tipping fees for greenwaste range from $10 to 

$15 per ton and tipping fees for sewer sludge range from $30 to $40 per ton. If the 

material was landfilled, the tipping fee would be $30 per ton. 

The sale price of compost varies widely and competes with fertilizers. Composting 

facilities generally sell their final compost product for around $30 per ton. Very high 

quality and specialty compost can command a price of $90 a ton. Chipping and 

grinding facilities sell a final product like fuel for waste-to-energy plants for about 

$10 per ton. 

For facilities that compost by windrowing the feedstock (which is the dominate 

method in the SCAB) operational costs include leasing unimproved land, leasing 

equipment (i.e., grinders and front-end loaders), and low-skilled labor. These 

operations are generally not labor intensive. An average size composting facility has 

5 to 10 employees. Operational costs are higher for facilities that transport their final 

products since they incur additional costs for trucks and drivers. Generally, these cost 

are recouped by having the customer pay shipping costs. Chippers and grinders incur 

similar costs to composting facilities. 

Sanitation agencies that do not currently compost sewer sludge incur costs for 

disposing of the sludge by land spreading. These agencies must pay for the sludge to 

be transported (to Kerns, Kings, and/or Riverside Counties). Currently the transport 

cost including labor and tipping fee is approximately $38 per ton and is expected to 

increase if the disposal site is further away from the SCAB. 

OVERVIEW OF CURRENT REGULATORY REQUIREMENTS 

There are three levels of regulatory requirements that apply to the composting and 

chipping and grinding industries: 1) federal requirements (i.e., U.S. Environmental 

Protection Agency or EPA; 2) state (i.e., the California Air Resources Board (CARB) 

and the California Integrated Waste Management Board (CIWMB)), and, 3) local 

(i.e., the AQMD, local governments, and local enforcement agencies). Each of these 

agencies’ regulatory structure is designed to deal with different issues and while not 

necessarily driven by air issues some may indirectly benefit air quality. None of the 

existing regulations directly address air quality impacts from these operations. The 

following is an overview of federal, state and local regulatory programs that are 

applicable to the chipping and grinding and composting industries. 
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Proposed Rule 1133 1 - 10 March 2002

Federal Requirements 

The federal Clean Air Act requires the AQMD to adopt an AQMP that identifies a 

control strategy to demonstrate compliance with the federal ambient air quality 

standards. To address this federal mandate, the 1997 AQMP and 1999 Amendments 

to the 1997 Ozone State Implementation Plan for the SCAB included Control 

Measure WST-02 – Emission Reductions from Composting. The U.S. EPA approved 

these plans making the development of this control measure federally enforceable. In 

addition to air quality issues, there are other federal requirements that apply to 

composting operations. Specifically, the federal requirements focus mainly on water 

and solid waste (i.e., sewage sludge) issues. The following is a brief summary of 

these requirements. 

Resource Conservation and Recovery Act 

In 1976, Congress enacted the Resource Conservation and Recovery Act (RCRA), an 

amendment to the 1965 Solid Waste Disposal Act. RCRA calls for conservation of 

energy and natural resources, waste reduction, and environmentally sound waste 

management practices. In addition, RCRA encourages states to develop plans for 

non-hazardous industrial solid waste and municipal solid waste (MSW) management, 

sets criteria for MSW landfills, as well as for other solid waste disposal facilities, and 

prohibits the opening dumping of solid waste. Congress delegated authority to U.S. 

EPA to develop specific regulations to implement the requirements of RCRA. Solid 

waste regulations have been promulgated in the Code of Federal Regulations under 

Title 40, Chapter I, Subchapter I, Parts 240-282 (40 CFR Parts 240-282). As a result 

of RCRA’s prohibition on open dumping of solid waste other disposal alternatives for 

sewage sludge has been pursued including land spreading (treated sludge is spread 

over crop land as fertilizer), aerobic digestion, and composting. 

National Pollutant Discharge Elimination System

The National Pollutant Discharge Elimination System (NPDES) is an EPAimplemented program that requires permits for discharging pollutants from facility 

operations into water3. Even though the NPDES program focuses on water pollution 

from all types of industries, NPDES also applies to owners or operators of facilities 

that treat and handle sewage sludge, including composting with sewage sludge. The 

criteria and standards for NPDES are quite extensive and have been promulgated in 

several parts of the Code of Federal Regulations under Title 40, Chapter I, Subchapter 

D, Parts 122, 123, 124 and 125 (40 CFR Parts 122–125). 

Sewage Sludge Disposal Standards

EPA promulgated standards for the use or disposal of sewage sludge in Title 40, 

Chapter I, Subchapter O, Part 503 of the Code of Federal Regulations (40 CFR Part 

503). 40 CFR Part 503 contains requirements for the control of pathogens, vectors, 

and heavy metal for sludge composting operations. In particular, to qualify as Class 

A compost Appendix B to Part 503-Pathogen Treatment Processes, generally requires 

processes to further reduce pathogens (PFRP). PFRP requires that open windrow 

composting maintain the temperature of the compost to be 550

 C or higher for 15 days 

or longer, and during this time there must be a minimum of 5 turnings of the 

 

3

 40 CFR Part 122, §122.1 (b). 
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Proposed Rule 1133 1 - 11 March 2002

windrows. For in-vessel or aerated static pile (ASP) composting, the PFRP requires 

the active pile temperature be at least 550 C or higher for 3 days. 

State Requirements 

State law also requires the AQMD to adopt an AQMP that identifies a control 

strategy to demonstrate progress towards achieving the state ambient air quality 

standards. The 1997 AQMP and 1999 Amendments to the 1997 Ozone State 

Implementation Plan for the SCAB that included Control Measure WST-02 – 

Emission Reductions from Composting, was also submitted to the CARB to comply 

with state law. These air plans identified composting as a source of ammonia, PM10, 

and VOC emissions. As such, Control Measure WST-02 required the development of 

viable control to reduce the emissions from this industry by 2003. In addition to air 

quality requirements, there are several other state requirements that may apply to 

chipping and grinding and composting operations. Specifically, these state 

requirements focus on air, water and solid waste (i.e., sewage sludge) issues. The 

following is a summary of these requirements. 

California Air Resources Board

In addition to reviewing and approving the AQMP, CARB permitting requirements 

can affect composting and chipping and grinding operations that use portable 

equipment. As of December 1, 1999, CARB runs the “Statewide Registration 

Program” which regulates portable engines and portable engine-driven equipment 

units. Once equipment is registered in this program, engines and equipment units can 

operate throughout California without the need to get individual permits from local 

air pollution control districts, such as the AQMD. The AQMD is preempted from 

permitting, registering, or regulating portable engines and portable equipment units 

properly registered with the CARB. 

Owners and operators of portable engines and portable equipment units that meet the 

definitions and requirements of the registration program are eligible for statewide 

registration. Facilities that conduct chipping and grinding or composting activities 

operate portable engines that are affiliated with equipment, including but not limited 

to, wood chippers, tub grinders and trommel screens. It is common for these types of 

facilities to have equipment operating pursuant to Statewide Registration Permits. 

California State Legislature: California Integrated Waste Management Act 

Recognizing the need for integrated waste management practices, in September 1989, 

the California state legislature passed Assembly Bill (AB) 939 – California Integrated 

Waste Management Act, into law, which was incorporated into the California Public 

Resources Code, Division 30, §40000 et seq. (Division 30). Division 30 is 

implemented by CIWMB. Section 41780-41786 of the law contains mandates for 

cities and counties to achieve a total waste diversion of 25 percent by 1995, and a 

total waste diversion of 50 percent by 2000, as established by a 1990 baseline. 

Division 30 also requires California to secure and plan for adequate long-term 

disposal capacity. Since organic materials, such as food and greenwastes, represented 

approximately 25 percent of California’s waste stream in 1999, recycling, reuse, and 

source reduction have been widely promoted to achieve the goals of Division 30. 
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Proposed Rule 1133 1 - 12 March 2002

California Integrated Waste Management Board 

In June 1995, the CIWMB promulgated a set of regulations governing composting 

operations and facilities. The CIWMB currently regulates approximately 87 

composting facilities operating in California in accordance with the California Code 

of Regulations, Title 14, Division 7, Chapter 3.1 – Composting Operations 

Regulatory Requirements (Chapter 3.1). Depending on the type of composting 

materials and the throughputs, affected facilities are required to obtain a Registration 

Permit, a Standardized Composting Permit, or a Full Solid Waste Facilities Permit 

(Full Permit). Full Permits require the preparation of an Environmental Impact 

Report (EIR) and are issued by CIWMB while Registration and Standardized Permits 

are issued through local enforcement agencies (LEAs), such as the environmental 

health departments. According to the CIWMB data-base, sixteen of the twenty-seven 

facilities in the AQMD’s jurisdiction are identified as having a CIWMB permit. 

Currently, the CIWMB is revising these regulations to address a number of issues 

relating to composting activities including an increasing number of complaints 

regarding odor at compostable organic materials transfer/processing operations and 

facilities. The CIWMB’s staff is concerned that continued problems with odors could 

limit the growth of the composting industry. As such, the CIWMB is proposing to 

revise its regulations to require odor minimization plans developed by the composting 

facilities. The odor minimization plans would be reviewed only if there exists a 

documented public nuisance. While odors are under the regulatory oversight of the 

jurisdiction’s local enforcement agency, odors are an indication that the piles are 

emitting ammonia and VOCs. The AQMD retains authority over emissions from 

these facilities. 

Though chipping/grinding facilities are not currently required to obtain permits, 

CIWMB is developing a proposal to amend the permit requirements in Chapter 3.1 to 

include chipping/grinding and other operations that handle compostable organic 

materials. 

Regional Water Quality Control Board 

The Regional Water Quality Control Board (RWQCB), a state agency with regional 

offices throughout California, enforces EPA-issued National Pollutant Discharge 

Elimination System (NPDES) permits. In addition, the RWQCB focuses on 

wastewater generation, water demand, the capacity of existing or planned stormwater 

drainage systems and potential new sources of polluted run-off, and potential 

depletion of groundwater supplies or interference with groundwater recharge. In the 

case of composting and chipping/grinding facilities, the RWQCB has required 

various sites to be graded, paved, and surrounded by berms and other drainage-related 

protections to prevent run-off and the leaching of composted/chipped ground 

materials into the groundwater. 

Local Requirements 

There are several local requirements that may apply to chipping/grinding and 

composting operations. Specifically, these requirements focus on air, land use and 

solid waste (i.e., sewage sludge) issues. The following is a summary of these 

requirements. 
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Proposed Rule 1133 1 - 13 March 2002

AQMD Rule Requirements

Currently, operators of composting and chipping/grinding facilities located in the 

district are required to comply with AQMD Rule 402 – Nuisance, Rule 403 – 

Fugitive Dust, and Rule 203 – Permit to Operate for equipment that require permits. 

However, none of these rules require specific emission controls at composting or 

related facilities. 

Local Enforcement Agency Requirements

There are several different local (i.e., city or county) enforcement agencies or LEAs 

that act as the either the permitting or enforcement division of the CIWMB, 

depending on the throughput and type of compostable materials. For example, the 

local department of health services, on behalf of the CIWMB, issues Registration and 

Standardized permits and enforces the requirements in these permits for facilities with 

lower throughputs. However, for facilities that have throughputs that require a Full 

Permit issued by the CIWMB, the LEA is only responsible for enforcing the 

requirements in the Full Permit. For either type of permit scenario, the LEAs are 

responsible for handling and investigating complaints from composting and 

chipping/grinding operations. 

City or county offices in the jurisdiction where a facility is located approve or deny 

conditional use permits, and have the authority over land use and the siting of 

composting facilities, transfer stations, or other solid waste management activities. 

Sewage Sludge Ordinances

In addition to EPA’s federal requirements regarding the use or disposal of sewage 

sludge, there are local ordinances or restrictions throughout California and other 

states that ban the import and land application use of certain grades of sewage sludge. 

For example, 14 counties within California, with Riverside county being the only one 

located within the AQMD’s jurisdiction, have passed ordinances or permitting 

requirements that either ban or restrict the application of certain grades of sewer 

sludge onto farmland4

. In addition, recent litigation and regulations in both Kern and 

Kings counties have resulted in ordinances that ban the import of certain classes of 

sewage sludge starting early 2003. Other states such as Pennsylvania, Vermont, and 

New Hampshire, have also passed similar ordinances to ban or limit the application of 

sewer sludge onto land. These restrictions will likely force the water treatment plants 

within the AQMD’s jurisdiction, throughout California and the nation to further 

process the sewage sludge so that it can be recycled and used on farmland. 

Local Governments

Local government zoning and general plan standards determine where composting 

and chipping and grinding activities can occur. In addition, local governments grant 

conditional use permits if the jurisdiction has determined that special conditions and 

approvals are necessary. Local governments, through curb side recycling programs, 

may also be providing some composters with greenwaste feedstock. 

 

4

 County of Riverside Ordinance No. 744 – Regulating the Processing of Greenwaste. 
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Proposed Rule 1133 1 - 14 March 2002

OTHER ISSUES FACING THE COMPOSTING INDUSTRY 

Public Nuisance Issues 

Uncontrolled emissions, odors, and dust generated by windrow composting and 

chipping and grinding operations are often sources of public complaints. Emissions 

and odors can dramatically increase if the windrows are not maintained properly or 

chipped and ground material is allowed to decompose. Some feedstocks like food 

waste, dairy products, manure, sewer sludge, are odorous. Also, some outdoor 

blending operations of putrescible feedstocks generate odor related public nuisance 

complaints. Dust may also result from open feedstock preparation areas, chipping 

and grinding operations, and compost turning, curing, screening, storage, and loading. 

The problem can be worse during high winds. 

Over the last two years, thousands of odor and dust complaints have been filed with 

the AQMD and with local enforcement agencies (LEAs). In particular, between 

January 1, 2000 and December 31, 2001, the AQMD received 470 public complaints 

regarding composting and chipping and grinding operations. The LEAs have 

received over 2,600 complaints regarding composting and chipping and grinding 

operations.5 The AQMD staff has issued notices to comply (NC) and notices of 

violation (NOVs). The AQMD does not have records of enforcement actions taken 

by the LEAs. Table 1-2 summarizes this information. 

Table 1-2 

2000-2001 Public Complaints/AQMD Enforcement Actions 

On Composting and Chipping and Grinding Operations 

Agency # of Complaints # of NCs/NOVs 

AQMD 470 55 (30 NCs and 27 NOVs)

LEAs 2,600+ N/A 

The AQMD’s role in addressing public complaints from these facilities has been 

affected by AB 59 that become law in 1995. Under this law, all air districts in 

California are to refer public complaints pertaining to odors from a composting 

facility that is subject to the CIWMB’s regulatory requirements to the LEA. Odors 

from non-composting activities like chipping and grinding activities, mulching, and 

ADC are under the AQMD’s jurisdiction. Non-odor related public complaints 

including dust-, permitting-, or emissions-related nuisances affecting the public are 

within the AQMD’s jurisdiction. 

Waste Diversion (AB 939) 

AQMD staff has received public testimony that composting is an integral program 

used to comply with AB 939 (the California Integrated Waste Management Act of 

1989) Waste Diversion requirements. AB 939 is implemented by the CIWMB, and 

mandates cities and counties to achieve a 25 percent total waste diversion by the year 

 

5

 This number underestimates the total number of complaints to LEAs because not all the LEAs maintain 

the data in a tabulated format and not all the composting and chipping and grinding facilities were included 

in the AQMD’s data request. 
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Proposed Rule 1133 1 - 15 March 2002

1995, and a 50 percent waste diversion by the year 2000, based on the 1990 baseline 

year. Organic materials, one component of the waste stream, can be diverted from 

landfills through methods including use as ADC, fuel at waste-to-energy facilities, 

mulch, composting, soil amendments and erosion control. 

AQMD staff has conducted an evaluation of the current practices in achieving the 

waste diversion goals of AB 939. The CIWMB measures compliance with AB 939 

waste diversion goals by measuring the reduction in the amount a given jurisdiction 

disposes to the landfill. There is no quantifiable measurement of the quantity of 

waste actually being diverted. For each jurisdiction a maximum allowable disposal 

amount is calculated which represents a 50 percent reduction of disposed waste from 

1990. To meet the diversion rate requirement, a jurisdiction may not dispose more 

than the maximum allowed amount. Each jurisdiction must also submit an annual 

report that includes information on all programs being implemented to divert waste 

disposal to a landfill. Organics are only one of the waste categories that is affected to 

achieve the AB 939 goals. Jurisdictions also promote source reduction and the 

recycling of paper, glass, and aluminum cans, and household hazardous waste. 

The CIWMB estimates that the year 2000 statewide diversion rate is at 42 percent. 

As indicated above, it is unknown how much each individual waste diversion 

program contributes to the overall waste diversion rate. AB 939 requires each 

jurisdiction to prepare, adopt, and submit to the CIWMB a source reduction and 

recycling element (SRRE) that demonstrates how the jurisdiction will meet the 

CIWMB’s mandated diversion goals. The CIWMB approves the information 

submitted by each jurisdiction, but does not keep track of each individual program’s 

effect on diversion. It is the burden of each individual jurisdiction to show to the 

CIWMB that the diversion mandate is being met. While the database does not 

provide specific information on the amount of waste diverted from each of these 

programs, it does indicate an intention to divert waste by using a variety of programs. 

These programs include: source reduction, composting, recycling, specials waste, 

public education, policy incentives, facility recovery, transformation, and household 

hazardous waste. Recycling and source reduction are the preferred programs used by 

the most number of jurisdictions to achieve the targets. Recycling programs included 

curb-side pick up, drop-off programs and special programs. Source reduction 

included thrift shops, business programs, xeriscaping, and backyard composting 

(proposed to be exempt from PR 1133). 

The CIWMB further analyzes the SRRE documents to determine waste stream 

characteristics. Based on a 1999 waste characterization study conducted by the 

CIWMB, all organics contribute about 35.1 percent to the overall waste stream. 

Organics include materials that are eligible for composting programs. Organics waste 

includes food, landscaping materials, agricultural crop residues, manures, textiles, etc. 

Table 103 lists a break-down of the organics-only waste stream based on the 

CIWMB’s records. 
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Proposed Rule 1133 1 - 16 March 2002

Table 1-3 

Types of Organics Contributing to Waste Stream 

Organic Material Type Percentage of Waste Stream 

Food 15.7% 

Leaves & Grass 7.9% 

Prunings & Trimmings 2.2% 

Branches & Stumps 0.1% 

Agricultural Crop Residues 0.0% 

Manures 0.1% 

Textiles 2.1% 

Remainder/Composite Organic 6.9% 

Recent studies by the CIWMB show that while organics are prevalent in the waste 

stream, many of these organic materials are also associated with odor and emissions 

problems. For example, Table 1-4 indicates the top ten materials in the waste stream. 

Food waste makes up the highest percentage of the waste stream. The AQMD staff 

has received a significant number of odor complaints from composting-related 

activities that includes food wastes. Grass is another organic waste material that has 

odor problems associated with it. Grass can be an issue in greenwaste composting 

leading to higher emissions and odors because of its moisture and rapid 

decomposition. 

Table 1-4 

Top Ten Materials in Waste Stream 

Material Percentage of Waste Stream 

Food 15.7% 

Remainder/Composite Paper 9.6% 

Leaves & Grass 7.9% 

Remainder/Composite Organic 6.9% 

Lumber 4.9% 

Uncoated Corrugated Cardboard 4.6% 

Other Miscellaneous Paper 4.4% 

Newspaper 4.3% 

Film Plastic 3.9% 

Other Ferrous Metal 2.4% 

There are a number of different programs being used to divert greenwaste that rely on 

source reduction, transformation, public education, incentive programs, and 

composting. These programs are listed in Table 1-5. 

Table 1-5 

CIWMB Identified Examples of Programs to Divert Greenwaste 
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Proposed Rule 1133 1 - 17 March 2002

Programs Description 

Xeriscaping, grasscycling Landscaping to reduce waste 

Backyard composting Composting at home by residents 

Mulching Gardening product 

Seasonal Collections Holiday foliage 

Commercial Composting Creation of commercially sold gardening products 

Alternative Daily Cover Substitute cover for soil at landfills 

Fuel For waste-to-energy facilities 

Bulking agent For use in co-composting of sewer sludge, food 

waste, manure 

Landfill ban on 

greenwaste 

Not accept greenwaste 

Tipping fee incentives Structure fees to benefit source reduction 

Collection rate incentives Structure fees to benefit source reduction 

School composting Composting conducted at schools with on-site 

materials 

A review of the CIWMB’s database on local government’s SRRE’s indicates ADC 

appears to be an important program currently being using to achieve the AB 939 

diversion targets. For example, in the facility recovery component of the SRRE, 

approximately 58 local governments (in the four counties) indicated that they rely on 

a composting facility program, while approximately 103 local governments indicated 

they rely on ADC programs. 

A study was also conducted by the CIWMB to assess California’s compost and mulch 

producing infrastructure. The study analyzed both composters and processors (i.e., 

process material, but do not compost). The surveys of the chippers and grinders are 

good general indicators of the types of programs being relied upon to divert 

greenwaste from landfills for several reasons. All the greenwaste that is diverted 

from landfills must be processed (i.e., chipped and ground) before it can be put to 

other uses, including the greenwaste collected by local jurisdictions in curb-side 

recycling programs. The chippers and grinders in the survey are stand-alone 

operations that do not compost on site, so it is good indication of the overall market 

demands for processed greenwaste.6

 There are more chippers and grinders (47) than 

composters (28) in the AQMD’s jurisdiction and the chippers and grinders handle 3 

times more greenwaste than the composters. This study (focusing on the chippers and 

grinders data) indicates that in southern California alternative daily cover (ADC) is 

the most heavily relied upon method jurisdictions use to divert greenwaste from 

landfills (46%), followed by fuel for waste–to-energy facilities (25%), and then 

composting (18%). The study also acknowledged that southern California’s use of 

ADC leads other regions in California. Even when the composters’ product 

distribution is considered, ADC and fuel are still important to waste diversion. 

 

6

 The survey of the chippers and grinders was viewed as a better overall indicator of the markets since 

chippers and grinders facilities serve as the first stage in the diversion process. For example, chippers and 

grinders provide raw feedstock to composters. Therefore, using composter data may result in double 

counting of product markets. Further, any chipping and grinding performed by the composters is primarily 

for processing composting-related products and not as reflective of the other markets for processed green 

waste. 
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Proposed Rule 1133 1 - 18 March 2002

Composters in southern California produce compost (50% of their products), ADC 

(16%), fuel (6%), and mulch (13%). 

The AQMD staff conducted a survey of composting and related facilities in the 

region. The composting facilities and most of the chipping and grinding facilities 

were visited by AQMD staff and the surveys completed as part of that visit. Surveys 

were also mailed to other facilities and some facilities were surveyed over the 

telephone. Part of the AQMD’s survey included collecting information on the 

amount of greenwaste that was being composted in the AQMD’s jurisdictional 

boundaries. The AQMD’s survey of the chipping and grinding and composting 

facilities supports the finding that ADC and fuel for waste-to-energy facilities are key 

programs being relied on by local governments in general for achieving the AB 939 

waste diversion goals. Based on this survey, the AQMD staff also determined that 

the total amount of greenwaste used either as a bulking agent for co-composting or at 

a greenwaste composting facilities was approximately 1.1 million tons a year. Of the 

3 million tons of material processed at chipping and grinding facilities, approximately 

15-40% of the material is used for waste-to-energy, 50-60% for ADC, and 10% for 

mulching or composting. 

The prevalence of ADC as a key program for greenwaste diversion is also recognized 

by the CIWMB. The CIWMB has summarized the reported waste-derived ADC 

since 1996 in Table 1-6. 

Table 1-6 

CIWMB Statewide ADC Analysis (tons/year) 

ADC Type 1996 1997 1998 1999 2000 

Green Material 560,266 625,198 1,083,673 1,396,026 4,302,4437

Other (mainly Sludge; 

Treated Auto Shredder 

Residue; C&D) 

383,669 659,339 587,285 791,786 666,042

Total ADC 943,935 1,284,537 1,670,958 2,187,812 4,968,485

ADC % of Total Disposal 3.0% 3.5% 4.5% 5.5% 15%

Based on available data, AQMD staff has not been able to quantify the extent to 

which these programs are actually being utilized to achieve the AB 939 waste 

diversion goals. There are no records that indicate which programs are the most 

important to achieving the AB 939 waste diversion goals. Therefore, a qualitative 

assessment of surveys and other information has been conducted to determine the 

relative importance of each program in diverting waste. 

To further address the waste problem in California, the CIWMB is exploring 

conversion technologies that would convert organic materials, including greenwaste, 

into high-value products like energy, alternative fuels (ethanol), solvents, and other 

products. These technologies include hydrolysis, gasification, and anaerobic 

digestion. Hydrolysis is the chemical decompostion process that uses water to split 

the chemical bounds of substances. This process can be used to create products such 

 

7

 Preliminary amounts. CIWMB Staff is currently reviewing revised DRS reports from counties. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 19 March 2002

as ethanol, specialty chemicals, fuels, and citric acid for the beverage industry. 

Gasification is a process that uses heat, pressure, and steam to convert materials 

directly into a gas composed primarily of carbon monoxide and hydrogen. The 

products from this process can be used as a fuel to generate electricity or a gasoline 

additive. Anaerobic digestion is the biological decomposition of matter in the 

absence of oxygen and is used to produce compost, fertilizer, and methane. The 

emissions from all of these processes are controlled unlike the emissions from 

windrow composting. 

The CIWMB is currently analyzing the regulatory issues surrounding the use of 

conversion technologies including permitting, public health standards, and diversion 

credits. The current law allows for 10 percent of the diversion credit to be met by 

these transformation technologies if certain requirements are met. 

Regardless of the fact that composting does not appear to be as highly relied upon as 

other programs, the AQMD staff is cognizant of the AB 939 requirements on local 

governments and is striving to draft a regulatory program that would not adversely 

affect AB 939, while achieving clean air objectives. For this reason, AQMD staff has 

focussed its efforts in identifying and quantifying the impacts to the specific 

industries affected by the proposal. 

Environmental Justice 

In California, environmental justice is generally considered to be a call for the fair 

treatment of people of all races, cultures, and incomes with respect to the 

development, adoption, implementation, and enforcement of environmental laws and 

polices. In October 1997 the AQMD Governing Board adopted an environmental 

justice policy. The four guiding principles are: 

• All basin residents have the right to live and work in an environment of clean 

air, free of airborne health threats; 

• Government is obligated to protect public health; 

• The public and private sectors have the right to be informed of scientific 

findings concerning hazardous and toxic emission levels, and to participate in 

the development and implementation of adequate environmental regulations in 

their communities; and 

• The (AQMD) governing board is to uphold the civic expectation that the 

public and private sectors of the basin will engage in practices that contribute 

to a healthy economy and truly livable environment." 

Environmental justice can be an issue in the siting of composting operations because 

of odors and dust impacts on neighborhoods from uncontrolled operations. The 

number of public nuisance complaints that the AQMD and LEAs have received 

regarding composting and related activities shows that these operations are having an 

impact on the surrounding community. As such, regardless of air quality regulations, 

environmental justice issues will affect the ability for future expansion of composting 

operations unless these issues can be adequately addressed. Controls to reduce 

emissions are expected to go a long way in addressing these impacts and would be 

consistent with the AQMD’s environmental justice policy. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 1 - 20 March 2002

Regulatory Limits on Land-Application of Wastewater Sludge 

Currently, sewer sludge that has been treated to reduce pathogens and metals is 

trucked from this region to Kings and Kern Counties where it is spread on croplands. 

Sewer sludge enriches the soil and can supplement or replace commercial fertilizers. 

There are two classes of processed sludge. Class A sludge must undergo pathogen 

reduction to be below detectable levels. Class A can be used on edible vegetables and 

plants. Class B sludge must undergo pathogen reduction to ensure the pathogens are 

reduced to levels that are protective of public health and the environment. Class B 

sludge is only used on non-edible crops, forests, and reclamation sites. Class B 

sludge can not be used for composting. Public concerns over Class B sludge used on 

croplands in Kings and Kern Counties has resulted in these jurisdictions placing 

limitations on Class B sludge. As a result, additional options to deal with the Class B 

sludge will need to be developed. This could include additional composting of sludge 

in the region if the sludge is treated to Class A levels. Therefore, there is an increased 

need to resolve the environmental impacts issues associated with co-composting 

operation so that additional co-composting facilities can be sited in the AQMD’s 

jurisdiction. The majority of the co-composting facilities in the region have already 

indicated that they will enclose active composting and vent emissions to a control 

device. 

NECESSITY FOR PROPOSED RULE 1133 

PR 1133 was developed to fulfill the AQMD’s commitment in the 1997 AQMP and 

1999 Amendments to reduce ammonia and VOC emissions from composting and 

related operations. As such, this rulemaking is part of an integral plan to achieve 

healthful air in the region. Currently, the manner in which composting is conducted 

by windrows results in a source of VOC and ammonia emissions. Composting is also 

a source of numerous public nuisance complaints regarding dust and odors. The 

former would be addressed by this rulemaking. Various control techniques have been 

applied to bio-solid composting throughout the U.S. to reduce emissions and public 

nuisance complaints. This report examines viable control options for the local 

composting industry. 
CHAPTER II 

 

INDUSTRY PROFILE AND EMISSIONS INVENTORY 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 1 March 2002

INTRODUCTION 

This chapter discusses the following: 

9 Industry Profile; and, 

9 Emissions Inventory. 

INDUSTRY PROFILE 

The AQMD staff developed an industry profile for the composting and related 

operations industry based on information obtained from the CIWMB permit database, 

AQMD permit system, AQMD-conducted surveys and site visits, and comments from 

the public. Through this process, the AQMD staff identified 277 facilities. For the 

purpose of rule development, the facilities that make up the composting and related 

operations industry are classified into four categories: 1) co-composting facilities; 2) 

greenwaste composting facilities; 3) chipping and grinding facilities; and, 4) exempt 

facilities. 

Co-composting facilities include facilities that compost putrescible materials such as, 

sewage sludge, manure, and food wastes in combination with greenwaste. 

Greenwaste composting facilities are composting facilities that use only greenwaste 

as feedstock materials. Chipping and grinding facilities are facilities that chip and 

grind greenwaste for use in composting, waste-to-energy, and alternate daily recovery 

(ADC) at landfills, or to produce mulches. Finally, exempt facilities are those 

facilities that are categorically exempt from Proposed Rule 1133 based on the type of 

operation (i.e., transfer station/MRF, sewage treatment, fertilizer blending/bagging, 

manure shredding, landscaping/nursery/gardening, agricultural farm composting, 

winery, community composting, portable chipping/grinding, botanical 

garden/arboretum, and public park/camping.) 

Facility and throughput information was compiled based on information obtained 

from the CIWMB, the AQMD Permit System, the AQMD-conducted surveys and site 

visits, and independent contractor’s studies. 

Table 2-1 - Composting Industry and Related Operations, provides a profile of the 

composting and related operations industry. 

Table 2-1 

Composting Industry and Related Operations 

CATEGORY 

Number 

of 

Facilities 

Throughput 

(tons/year) 

Co-Composting 12 922,190 

Greenwaste-composting 16 832,191 

Chipping/Grinding 47 3,033,092 

Exempt Facilities 202 36,865 

 

Total 277 4,824,338 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 2 March 2002

The geographical distribution of the composting and related operations industry is 

approximately 42, 19, 16, and 23 percent for Los Angeles, Orange, Riverside, and 

San Bernardino counties, respectively. Table 2-2, Composting Facilities by County, 

provides number of facilities and throughputs in each of the counties by industry 

sector. 

Table 2 – 2 

Composting Facilities by County 

Number of Facilities by County (Throughputs – tons/year) 

Category Los Angeles Orange Riverside San Bernardino

Co-Composting 3 (18,570) 2 (38,329) 1 (365,000) 6 (500,291) 

Greenwastecomposting 6 (52,516) 3 (240,490) 4 (189,745) 3 (349,690) 

Chipping/Grinding 20 9 13 5 

Exempt Facilities 87 39 26 50 

Total 116 53 44 64 

EMISSIONS INVENTORY 

The 2001 baseline emissions inventory for the composting and related operations 

industry includes emissions from 12 co-composting and 16 greenwaste composting 

facilities operating in the AQMD’s jurisdiction. Emissions for co-composting and 

greenwaste composting were estimated by multiplying the facilities’ annual 

throughput with facility-wide average emission factors. For all but two facilities that 

compost in an aerated static pile (ASP) and an in-vessel system, the emissions are 

considered to be baseline emissions representing the existing setting and do not take 

into consideration future plans. In addition, the inventory includes emissions from 

the exempt facilities. This inventory therefore, represents the existing settings. The 

emissions inventory does not include PM10 emissions from fugitive dust at any of the 

facilities including chipping and grinding operations. From work on similar facilities 

(Rules 1158, 403, 1186), public nuisance complaints, and site visits, the AQMD staff 

believes that there are PM10 emissions from these operations. As such, the total air 

quality impact of this industry is underestimated. 

Emission Factor Development 

The emission factors used for the development of the inventory are based on field 

measurements that were conducted by the AQMD’s Technical Services Division. 

Specifically, field measurements were conducted at four co-composting facilities 

including, three outdoor windrow co-composting facilities and one in-vessel 

composting facility. The AQMD staff also conducted tests at one greenwaste 

composting facility. Complete source test reports are available from the AQMD. 

In general, the field measurements conducted included several samples in order to 

develop an emissions profile that would be reflective of different phases of the 

composting process (i.e., active composting and curing). The following section 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 3 March 2002

provides more information on the development of the emission factors and emissions 

profiles for co-composting and greenwaste composting only. 

Emission Factors for Co-Composting 

In 1995, as part of the PM10 Technical Enhancement Program (PTEP), the AQMD 

staff conducted an emission evaluation of four co-composting facilities, using the 

EPA approved Emission Isolation Flux Chamber method. The following summarizes 

the results of the source tests. Full source test reports are available from the AQMD. 

Based on the PTEP data for three windrow co-composting facilities, the AQMD staff 

developed the emission factors used to estimate ammonia and VOC emissions from 

co-composting operations. Only data from the windrow type of operations were used 

since the windrow composting method represents the current state of the industry, and 

this method of composting is considered to be the source of baseline emissions. The 

estimated emission factors for ammonia and VOC are 2.93 and 1.78 lb/ton mix, 

respectively. The estimated emission factors were calculated as the arithmetic 

average of data presented in Table 2-3 – Windrow Emissions Factors. 

Table 2-3 

Windrow Emissions Factors 

Facilities NH3 E.F. (lb/ton mix) (VOC) E.F. (lb/ton 

mix) 

RECYC Inc. @ Corona (1995) 2.7 0.53 

EKO System @ Corona (1996) 3.28 1.7 

San Joaquin Composting, Inc. @ Lost 

Hills (1996) 

2.81 3.12 

Average 2.93 1.78 

The emission factors presented in Table 2-3 are the weighted-average emissions 

factors for emission rates from different compost piles at different days in the cycle. 

The source tests used for this analysis contain data from the second day through the 

sixtieth day of composting cycle. 

Based on the available source test data, EPA’s pathogen reduction 15-day 

requirement, and information from other studies, for emissions purposes, staff 

assumed that the active phase of the composting cycle takes approximately 22 days. 

The active composting phase of the process is the time period where organic material 

decomposes at its fastest rate and emissions are generated at a high rate. 

The 22-day assumption is anecdotally supported by information found in EPA 503 

regulations and other studies found in the literature. In particular, an odor-emission 

study on manure composting conducted by University of Minnesota demonstrates that 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 4 March 2002

odor emissions generated from 3-day piles are at least six times greater than odor 

emissions of 28-day piles. By way of example, Figures 2-1 and 2-2 provide a 

graphical representation of the composting process, based on the source test 

conducted. These figures representing methane and ammonia emissions over time, 

which are consistent with AQMD staff assumptions on the emissions split time period 

for the active and initial curing phases of the composting process. 

Figure 2-1 - Methane Emissions vs. Time 

Figure 2-2 - Ammonia Emissions vs. Time 

Furthermore, PTEP data was also used to determine the emissions distribution for the 

co-composting process. The weighted-average emission factors of composting piles 

up to 22-days old were used to calculate the emission factors for the active phase of 

composting process. The weighted-average emissions factors of composting piles up 

to 60-days old were used to calculate the emission factors for the curing stage of the 

process. 

Based on the 22-day assumption, staff analysis indicated that, for ammonia, 50% of 

the emissions are released during the active phase and 50% of the emissions are 

released during the curing phase of the process. For VOC, staff analysis indicated 

0

0.2

0.4

0.6

0.8

0 10 20 30 40 50 60

days

lbs/hr - ft2

0

0.05

0.1

0.15

0.2

0.25

0.3

0 10 20 30 40 50 60

days

lbs/hr - ft2
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 5 March 2002

that 80% of the emissions are released during active phase and 20% of the emissions 

are released during the curing phase of the process. 

Based on the results of emissions profile analysis, the estimated ammonia emission 

factor for both active and curing phases of the process is equally estimated to be 1.47 

lb/ton mix. For VOC, the estimated emission factors are 1.42 lb/ton mix and 0.36 

lb/ton mix, for the active and curing phases, respectively. 

Emission Factors for Greenwaste Composting 

The AQMD staff conducted two source testing for greenwaste in September and 

November-December of 2001. Based on the weather conditions, the September and 

November-December tests are referred to as early fall and early winter tests, 

respectively. The early fall test was conducted using the EPA approved Emission 

Isolation Flux Chamber method. The early winter test was conducted using a remote 

sensing measurement technology called Boreal Laser Gas Finder. Basically, this 

technique measures the concentration and the volumetric airflow rate through large 

cross sections of the pile. The results of the cross section analysis are used to provide 

an estimate of emissions from the entire pile. For the purpose of this analysis, both 

early fall and early winter test results were used to develop the weighted-average 

emission factors for greenwaste composting. The early fall source test report is 

available upon request, and the early winter source test report will be available 

shortly. 

The following summarizes the results of AQMD staff’s greenwaste composting 

source tests and the development of related emission’s factors. 

Early Fall Source Testing 

The early fall test was conducted on four piles that were approximately 2-day, 14-

day, 45-day, and 70-day-old. Different age piles were tested to ensure representation 

at various stages of the composting process. 

To obtain the composite samples, testing was also conducted at various positions (up 

to ten positions) of each pile. The results of the composite sample’s emission rates 

are presented in Table 2-4 – Composite Emission Rates (Early Fall Test). 

Table 2-4 

Composite Emission Rates (Early Fall Test) 

2-day Pile 14-day Pile 45-day & 

70-day Pile 

NH3 Emission Rate (lb/hr•1000 ft2) 0.091 0.071 0.004* 

VOC Emission Rate (lb/hr•1000 ft2) 0.368 0.226 0.079* 

(*) Average of two piles 

The above emission rates were then used to estimate the emission factors presented in 

Table 2-5 – Composite Emission Factors (Early Fall Test). 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 6 March 2002

Table 2-5 

Composite Emission Factors (Early Fall Test) 

2-day Pile 14-day Pile 45-day & 70-day Pile 

NH3 Emission Factor (lb/ton 

greenwaste) 

0.69 0.61 0.02 

VOC Emission Factor (lb/ton 

greenwaste) 

2.8 1.95 0.3 

Based on previously described 22-day active phase assumption, the estimated active 

and curing emissions factors for greenwaste composting are presented in Table 2-6 – 

Emission Factors for Greenwaste Composting (Early Fall Test). 

Table 2-6 

Emission Factors for Greenwaste Composting (Early Fall Test) 

Active Composting Curing 

NH3 Emission Factor (lb/ton 

greenwaste) 

1.3 0.02 

VOC Emission Rate (lb/ton 

greenwastes) 

4.75 0.3 

Early Winter Source Testing 

The early winter test was conducted on three piles that were approximately 2-days 

and 14-days old. Different aged piles were also tested to ensure representation at 

various stages of composting process; however, the winter test was not conducted on 

the curing pile. Instead, the average emission rates in lb/hr/1000 ft2 of the 45 and 70-

day piles from the early fall test were used to represent curing emissions for the early 

winter test. 

The early winter emission rates are presented in Table 2-7 – Emission Rates (Early 

Winter Test). 

Table 2-7 

Emission Rates (Early Winter Test) 

2-day Pile 14-day Pile 45-day & 

70-day Pile 

NH3 Emission Rate (lb/hr•1000 ft2) 0.018 0.048* 0.004 

VOC Emission Rate (lb/hr•1000 ft2) 0.28 0.21* 0.079 

(*) Average of two piles 

The above emission rates were then used to estimate the emission factors presented in 

Table 2-8 – Emission Factors (Early Winter Test). 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 7 March 2002

Table 2-8 

Emission Factors (Early Winter Test) 

2-day Pile 14-day Pile 45-day & 70-day Pile 

NH3 Emission Factor (lb/ton 

greenwaste) 

0.06 0.24 0.03 

VOC Emission Factor (lb/ton 

greenwaste) 

0.91 1.06 0.5 

Based on previously described 22-day active phase assumption, the estimated active 

and curing emissions factors for greenwaste composting are presented in Table 2-9 – 

Emission Factors for Greenwaste Composting (Early Winter Test). 

Table 2-9 

Emission Factors for Greenwaste-Composting (Early Winter Test) 

Active Composting Curing 

NH3 Emission Factor (lb/ton 

greenwaste) 

0.3 0.02 

VOC Emission Rate (lb/ton 

greenwaste) 

1.96 0.5 

In summary, greenwaste composting weighted-average emission factors presented in 

Table 2-10 are used to develop an emission inventory profile of the composting and 

related operations industry. 

Table 2-10 

Weighted-Average Emission Factors for Greenwaste Composting 

Active Composting Curing 

NH3 Emission Factor (lb/ton 

greenwaste) 

0.83 0.02 

VOC Emission Rate (lb/ton 

greenwastes) 

3.44 0.4 

Based on this analysis, it was determined that for greenwaste composting, the 

majority of ammonia and VOC emissions are generated during active composting. 

These emission factors are believed to represent emissions for the current state of the 

industry. In general, instead of using windrow composting, with frequent turning by 

scarabs or wildcats, greenwaste facilities process mounded stockpiles of greenwaste 

without frequent turning. 

Additional Greenwastes Testing 

In addition to the early fall and early winter source testing conducted by the AQMD, 

the CIWMB and the City of Los Angeles also conducted three source tests: one at a 

chipping/grinding facility and two tests as greenwaste composting facilities, one of 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 2 - 8 March 2002

which is using the windrow composting technique. The testing was conducted with 

the Emission Isolation Flux Chamber approach. The staff, at both CIWMB and City 

of Los Angeles, have worked cooperatively with the AQMD staff to ensure consistent 

emissions analysis. Although the final results have not been completely reviewed by 

AQMD staff in time to be included in this report, AQMD staff will incorporate those 

test results to the greenwaste composting emissions analysis and report the revised 

analysis to stakeholders as soon as possible. 

 

Baseline Emissions 

Table 2-11 – Baseline Emissions Inventory provides an emission inventory profile of 

the composting and related operations industry. As shown in Table 2-11, the 

composting and related operations industry, as a whole, generates approximately 6.8 

tons per day of VOC emissions, which would place this industry as the second largest 

stationary source category, with the refinery industry being the highest source 

category. 

Table 2-11 

Emissions Inventory 

Emissions (tons/year) 

Total Emissions 

(tons/year) 

Emissions 

Factors 

NH3 VOC 

Process 

Throughput 

Tons/year NH3 

lbs/ton 

VOC 

lbs/ton Active Curing Active Curing 

NH3 VOC 

Co-Composting 922,190 2.93 1.78 677.8 677.8 654.8 166.0 1355.6 820.8 

GreenwasteComposting 832,191 0.85 3.84 345.4 8.3 1431.4 166.4 353.7 1597.8 

Chipping/ 

Grinding 3,033,092 

N/A N/A N/A N/A N/A N/A N/A N/A 

Exempt 

Facilities 

36,865 0.85 3.84 15.3 0.4 63.4 7.4 15.7 70.8 

Total 1038.5 686.5 2149.6 339.8 1725 2489.4 

 

Totals in tons per day based on 365 days per year 2.8 1.9 5.9 0.9 4.7 6.8 

Of this inventory, there are 7 co-composting and 12 greenwaste composting facilities that 

generate an annual VOC emissions exceeding the 10 tons per year threshold for major 

sources as defined in District Rule 3001. Depending on the throughput, the largest 

greenwaste facility is estimated to emit up to 600 tons per year of VOC, which would be 

considered among the top 5 VOC emitters in the SCAB. 
CHAPTER III 

 

CONTROL TECHNOLOGY ASSESSMENT 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 1 March 2002 

INTRODUCTION 

This chapter discusses the following: 

9 Composting Methods; 

9 Emission Control System (Biofilter); 

9 Demonstrated Control Efficiencies; and 

9 Chipping and Grinding Methods. 

COMPOSTING METHODS 

Emissions from composting can be reduced by maintaining optimal aerobic 

conditions, or utilizing state-of-the art emissions control technologies, such as 

aeration static pile (ASP), in-vessel, and biofilters. 

Optimized Practices 

Maintaining optimal aerobic composting conditions can reduce some emissions and 

odors from composting operations. The microorganisms responsible for composting 

function best within a given range of parameters such as carbon to nitrogen ratio, 

moisture content, oxygen concentration, pH, and temperature of the compost piles. 

Although optimal conditions can vary based on the type of feedstock, preferred 

ranges are typically in the following: 

Table 3-1 

Optimal Composting Conditions 

Characteristic Preferred Range 

Carbon:Nitrogen ratio 25:1 to 40:1 

Moisture content 50% to 60% 

Oxygen concentration 5% to 15% 

PH 6.5 to 8.0 

Temperature 130°F to 150°F 

Additionally, good practices for compost mixing, curing and storage can also reduce 

odors, dust and emissions; however, the amount of reduction cannot be easily 

quantified. 

Aerated Static Pile (ASP) 

ASP was developed to eliminate substantial land space requirement and other 

problems associated with windrow composting. ASP is an established technology 

where forced aeration is applied to provide direct, precise control of oxygen, 

temperature, and moisture conditions to the pile. Currently, there are approximately 

118 operational composting facilities in the U.S. utilizing the ASP technology, two of 

them are located in the AQMD jurisdiction. Some of the ASP facilities operate 

within enclosures for further control. These facilities handle a daily throughput 

ranging from about 0.1 dry ton to 300 dry tons. In addition, several groups in the 

AQMD jurisdiction also consider ASP for their facilities. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 2 March 2002 

With the ASP, feedstock is piled over a base of porous materials such as wood chips, 

which contains perforated aeration pipes. In order to avoid short circuiting, the 

porous base should be smaller than the base of the pile. The perforated pipes are 

connected to a blower that either pulls (negative pressure or suction) or pushes 

(positive pressure) air through the pile. The blower should be operated intermittently 

to maintain the 5% to 15% oxygen range and the uniform temperature. To provide 

insulation and prevent escape of odors during composting, the pile is usually covered 

with a thick layer (12 to 18 inches) of finished compost or bulking agent. 

With positive pressure aeration, contaminated air is pushed through the pile to the 

outer surface; therefore, is difficult to be collected for odor treatment. However, 

positive pressure aeration is more effective at cooling the pile because it provides 

better airflow. 

With a suction system, air is pulled through the pile from the outer surface. 

Contaminated air is collected in the aeration pipes and can be directed to an odor 

treatment system. To avoid clogging, condensed moist air drawn from the pile must 

be removed before reaching the blower. Negative aeration might create uneven 

drying of the pile due to its airflow patterns. 

A study conducted by City of Columbus, Ohio demonstrates that the weightedaverage odor emissions from an outdoor negative aeration pile is approximately 67% 

lower than those from an outdoor positive aeration pile. However, to provide 

flexibility in operations, some composting facilities aerate in both positive and 

negative modes. Negative aeration is usually used during the beginning of the 

composting process to greatly reduce odors. In enclosed active composting area, 

negative pressure aeration also reduces moisture released into the building, and thus, 

reduces fogging. Positive aeration is used mostly near the end of the composting 

cycle for more efficient drying of the compost. 

In summary, compared to traditional windrow composting, ASP provides a more 

precise control of oxygen and temperature conditions; therefore, it can reduce odors 

and emissions by promoting optimal aerobic conditions. However, currently there is 

no field measure available to quantify any additional emission benefit of ASP (i.e., 

lower pile emissions). An ASP confined in a building enclosure would capture 100% 

of its emissions to an emission control device that will be discussed later in this 

chapter. ASP also provides better flexibility to handle changes in compost feedstock 

quantity and quality. In addition, it requires less time to complete the active 

composting phase. With proper operation, active composting from an ASP might be 

completed within 20 to 28 days; therefore, more finished compost can be produced in 

a smaller footprint. Study conducted by Synagro Composting Facility indicates that, 

in comparison to windrows, ASP reduces the landspace requirement on the order of 

60%. There are two common forms of ASP: individual piles and extended piles. 

Individual Piles 

Individual piles are long triangular piles that are usually constructed with a width 

equal to about twice the height. The aeration pipes run lengthwise beneath the ridge 

of each pile and serve the entire pile. Each pile contains feedstock of roughly the 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 3 March 2002 

same recipe and age. Individual piles are practical when feedstock is available for 

composting at intervals. 

Extended piles 

To make more effective use of available space, another pile configuration called the 

extended aerated pile has been developed. Studies indicate that the area required for 

an extended pile is about 50% less than that for an individual pile. Extended piles 

consist of individual cells that are stacked against each other. Cells of new feedstock 

are constructed in one pile, and cells of nearing mature compost are placed in other. 

The space between the two piles allows the removal of an old cell from one pile and 

adding of a new cell to the other. Cells are usually constructed with a width equals to 

the pile’s height. Each cell contains one day’s volume of feedstock. Generally, each 

cell is aerated by its own blower and controlled by its own timer or temperature 

sensor. However, cells contain feedstock of roughly the same age can share a single 

blower by connecting the pipes with a header. Connecting several cells to one blower 

minimizes the number of blowers required, but also complicates the blower control 

system. 

Appendix A contains the list of ASP composting achieved in practice, which based 

mainly on the 1998 Biocycle survey. 

In-Vessel Composting 

In-vessel is developed to eliminate substantial land space requirement for windrow 

composting, as well as to overcome the deficiencies in windrow. In-vessel 

composting is an established technology where feedstock is confined within a 

building, a container, or a vessel. In-vessel methods rely on forced aeration and 

mechanical turning to speed up the composting. Currently, there are approximately 

50 operational composting facilities in the U.S. utilizing in-vessel technology; one of 

them is located in the District. These facilities handle a daily throughput ranging 

from less than 1 dry ton to over 100 dry tons. There are different types of in-vessel, 

such as silos, rotating drums, transportable containers, bin composting, and agitated 

bed, which are designed/manufactured by about 15 companies; however, bin 

composting, silo, and agitated bed are considered the most popular in-vessel systems 

used in composting operations. 

Bin Composting 

Bin composting is the most basic and simple in-vessel technique, where feedstock is 

contained in a bin with or without roof. Essentially, bin composting operates like the 

ASP; it includes forced aeration in the floor of the bin and requires little or no turning 

of the feedstock. Besides having the advantages of an ASP, bin composting can also 

eliminate weather problems, provide better temperature control, and reduce odors 

released to the atmosphere. 

Silo 

In composting operations, vertical silo is the most popular system where air is 

provided from the base through the feedstock. Contaminated air can be collected 

from the top of the silo and vented to an odor or emission control equipment. 

Feedstock is loaded at the top of the silo, and finished compost is removed from the 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 4 March 2002 

base. Typical active composting time is 14 days, so one-fourteenth of the silo volume 

must be removed and replaced daily. Compost is often cured in a second aerated silo, 

which minimizes land space. However, this composting method may be difficult to 

operate due to compaction, temperature and air-flow problems, which are associated 

with this process. 

Agitated Bed 

Agitated bed is a system where controlled aeration and periodic turning are 

combined. With this system, feedstock is placed at the front end of a long, narrow 

channel (bed). As the turning machine moves forward, it mixes the organic materials 

and discharges it behind itself. With each turning, the machine moves the feedstock a 

set distance toward the end of the bed. The length of a bed and the turning frequency 

determine the composting period. If the machine moves the organic materials 10 feet 

at each turning and the bed is 100 feet long, the composting period is ten days. 

Suggested composting periods for agitated bed system ranges from two to three 

weeks. 

Between turnings, aeration is provided through a set of aeration pipes, which locate in 

the floor of the bed. Since the organic materials along the bed are at different stages 

of composting, the bed is divided into different aeration zones. Each blower supplies 

air to one zone and is controlled by a temperature sensor or a time clock. 

Agitated bed composting, in combination with the use of building enclosures, are 

capable of capturing 100% of the process of emission and odors. This method also 

provides better process controls. This type of process can produce consistent quality 

compost, reduce the composting time cycle, and reduce operational costs, which can 

help offset its high capital costs. 

Attachment B contains the list of operational in-vessel composting facilities in the 

U.S. This list is compiled based on the 1998 Biocycle survey and the input from one 

major in-vessel designer firm. 

EMISSION CONTROL SYSTEMS (BIOFILTER) 

There are several types of emissions control systems that are capable of controlling 

ammonia and VOC emissions; however, this discussion is limited to biofilters, since 

it is the most economically feasible and most common type of control equipment in 

composting operations. 

Biofiltration is a well-established emission and odor control technology in Europe 

where over two hundred biofilters were in use as of 1984 (Eitner, 1984). In the 

United States, biofilters have been mainly utilized for the treatment of odors as well 

as VOC in wastewater treatment plans. Biofilters have recently gained better 

acceptance by composting and other operations such as body repair shops, 

MRF/transfer stations, pharmaceuticals, beer breweries, etc. To date, AQMD has 

issued 17 Permits to Operate biofilters and is processing 15 additional applications. 

Basically, biofilters use microorganisms that live in the biofilm; a thin layer of 

moisture surrounds the particles that make up the media, to adsorb and biologically 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 5 March 2002 

degrade contaminated air into non-harmful substances. In particular, VOC is 

oxidized to carbon dioxide and water, and ammonia is degraded into nitrate without 

creating aggravating pollution issues. 

In biofilter design, the selection of a media is a critical factor. For a biofilter to 

operate efficiently, a media must have a good adsorption capacity and good resistance 

to compaction, be able to provide a suitable environment for microorganism growth 

and reproduction, and have high porosity for minimal back pressure. Typically, 

biofilter media is made up of wood waste and small portion of compost, which would 

provide an air-filled porosity between 40% and 60% and a pH between 6 and 8. 

In order for a biofilter to perform at its best, several parameters should also be 

maintained: 

Moisture Content 

Maintaining proper and consistent moisture content in the biofilter media is essential 

to support microorganisms and to remove ammonia (by dissolution). Ideally, 

moisture levels in the media should be kept between 40% and 60% at all times; 

however, a range of 30% to 65% are proven acceptable. Since the media has a 

tendency to dry out due to the airflow, biofilters usually have a pretreatment stage 

that moisturizes the contaminated air before it reaches the media. However, moisture 

content should be carefully monitored to avoid biofilter clogging. 

Temperature 

The optimum operating temperature for a biofilter is between 80 o

F to 100 oF. In 

order to avoid damaging to microorganisms, influent gas in excess of 105 oF might 

require cooling prior to entering the biofilter. 

Backpressure 

There is no absolute number for optimal backpressure (increase in pressure above 

normal operating gauge pressure). Backpressure varies depending upon media type, 

bed depth, unit airflow, media age, and may range from less than 1 inch water column 

to over 10 inches water column. Backpressure will rise as biofilter media ages (if 

there are no leaks, shortcircuits, channels, or fissures in the media.) 

Maintenance 

Sophisticated monitoring protocols are helpful; however, they should not take the 

place of regular inspection for dry spots, leaks, cracks, fissures of the media, and the 

presence of odors. 

In composting, biofilters are usually used in conjunction with aerated static piles or 

in-vessel systems. Biofilters are known for their competitive capital and low 

operating costs compared to conventional technologies, such as carbon filtration, 

chemical scrubbers, or oxidation; however, it may take up a large land space. 

Biofilters are also known as the best systems to remove multiple odor-causing 

compounds at low concentration. If properly designed and operated, biofilter would 

achieve an overall control efficiency of 75% for ammonia and 90% for VOC 

(Appendix C). 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 6 March 2002 

There are several types of biofilters, such as single-layer open bed, multi-layer stack 

bed, etc. They all have two basic components: a media, and a piping system that 

distributes contaminated air through the biofilter. 

Single-Layer Open Bed Biofilter 

Single-layer open bed biofilter is the most typical biofilter used in the composting 

operations. With this type of biofilter, contaminated air is introduced though a 

distribution system, which typically contains perforated plastic pipes, embedded in a 

layer of gravel. Above this layer, there is a media of approximately 4-ft thick. The 

typical airflow rate is in the range of 3 cfm and 5cfm per ft2 of biofilter surface. An 

open bed biofilter also has a sprinkler system to keep the media moist, and a drainage 

system to drain excess water in the event of over watering or rain. 

Single-layer open bed biofilter takes up a lot of space and often causes compaction of 

the media, which results in an increased head loss. Depending on the usage, biofilter 

media might need replacement every 2 to 3 years. 

Multi-Layers Stack Biofilter 

Multi-layers stack biofilter is an enclosed system that can prevent compaction of the 

media and also minimize the space requirement. Since multiple units can be run in 

parallel, the biofilter will not be shut down during media replacement. This type 

biofilter can also minimize the risk of channeling of the contaminated air stream. 

DEMONSTRATED EMISSIONS CONTROL EFFICIENCY 

Biofiltration is an emission control system that has been widely used by the 

composting industry in the United States. The emissions control effectiveness for 

biofiltration is published in numerous studies. In addition, independent emissions and 

odors evaluations have also been conducted by facilities employing biofiltration. 

Appendix C – Biofilters in Operation at Composting Facilities in the United States, 

provide information on inlet and outlet emission rates for the biofilters systems cited. 

Based on these data, AQMD estimated the destruction efficiency of biofiltration to be 

75 and 90 percent for ammonia and VOC, respectively. 

Table 3-2 – Composting Methods, Capture and Control Efficiencies, provides a 

summary of methods used in the composting and related operations industry and their 

respective efficiencies in terms of controlling air emissions. 

Table 3-2 – Composting Methods, Capture and Control Efficiencies 

Control Equipment 

Efficiency 

Composting Over-all Control Efficiency 

Method 

Emissions 

Capture 

Efficiency Ammonia VOC Ammonia VOC 

Windrow 0% n/a n/a 0 % 0% 

ASP* 25 to 33 % 75.0% 90.0% 18.8 – 24.7% 22.5 – 45.0 

In-Vessel 100% 75.0% 90.0% 75.0% 90.0% 

*Additional emission reduction potential from ASP cannot be quantified at this time. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 3 - 7 March 2002 

CHIPPING AND GRINDING METHODS 

Chipping/grinding facilities chip and grind wood/green waste, which was mostly 

collected from landscaping or from cities’ curbside collection programs, and stockpile the 

processed materials until they are transferred to other facilities for different usage such as 

alternative daily cover (ADC), biomass fuel, mulch, or composting feedstock. 

Stockpiling green waste, especially those from the curbside collection where other 

putrescible wastes are not normally separated, for a period of time under certain moisture 

and temperature, will allow the organic materials to decompose anaerobically and 

generate odors as well as emissions. High temperature and VOC monitoring data 

obtained during the AQMD site visits of the chipping/grinding facilities demonstrate that 

those piles were in the process of decomposing. 

To prevent wood/green waste from decomposing, staff recommends that certain 

processed and unprocessed materials to be removed from the site within certain time limit 

that will be determined later in the rule development process. The explicit holding times 

might vary by the source of unprocessed materials and by the end usage of chipped and 

ground materials. 

Beside VOCs, chipping and grinding operations can also be sources of PM10. PM10 

results from the chipping, grinding and screening of wood/green materials. It can also 

result when high winds entrain materials from processed material piles. To address these 

issues, AQMD staff is recommending consideration of the following PM10 dust controls, 

which are based on the Best Available Control Measures (BACM) listed in Rule 403, 

Fugitive Dust: 

• Cover the chipped/ground material with tarps, plastic or similar covering; or 

• Install a three-sided barriers equal the height of the piles; or 

• Water the piles; or 

• Cease all outdoor chipping/grinding activities during high winds (greater than 

25 mph) or when visible plume extends more than 100 feet from the 

equipment. 
CHAPTER IV 

 

EMISSION REDUCTIONS AND COST EFFECTIVENESS 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 1 March 2002 

INTRODUCTION 

This chapter discusses the following: 

9 Emission Reductions; and, 

9 Cost-Effectiveness. 

EMISSIONS REDUCTIONS 

AQMD staff has evaluated three control scenarios for co-composting and three for 

green-waste composting. Additionally, AQMD has analyzed the impact of hauling 

the green and sewer sludge wastes to landfills. 

Co-Composting 

AQMD staff analyzed the following three control scenarios for the co-composting 

sector of the composting industry: 

Scenario 1

• Enclosure of the active and curing phase of the process and the utilization of 

Aerated Static Pile (ASP) system; and, 

• Venting of emissions to a control device (biofilter). 

Scenario 2

• Enclosure of the active phase of the process and the utilization of ASP 

• Utilization of a ASP system under negative pressure for the curing phase of the 

process (no enclosure); and, 

• Venting of emissions to a control device (biofilter). 

Scenario 3

• Utilization of a ASP system under negative pressure for the active and curing 

phase of the process (no enclosure); and, 

• Venting of emissions to a control device (biofilter). 

The following assumptions were made to analyze the previously described control 

scenarios for co-composting: 

1. The seven largest windrow facilities with a combined throughput of 894,175 

tons/yr would be subject to control; 

2. The ammonia emissions factor for the active phase of the process is the same 

as the emission factor for the curing phase of the process: 1.47 lbs/ton mix; 

3. The VOC emission factor for the active phase of composting is 1.42 lbs/ ton 

mix; 

4. The VOC emission factor for the curing phase of composting is 0.36 lbs/ton 

mix; 

5. The windrow method of composting is assumed to be the baseline source of 

emissions, having no emissions capture efficiency (0%); 

6. No emission reduction benefit for resting pile emissions is assumed for an 

ASP; 

7. The capture efficiency of negative-ASP during the active phase of the process 

is assumed to be 33%; 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 2 March 2002 

8. The capture efficiency of negative-ASP during the curing phase of the process 

is assumed to be 25%; 

9. Enclosure is assumed to mean total enclosure and therefore, having a capture 

efficiency of 100%; 

10. The destruction efficiency of biofiltration for ammonia emissions is assumed 

to be 75%; and, 

11. The destruction efficiency of biofiltration for VOC emissions is assumed to be 

90% percent. 

The following equations where used to calculate emission reductions: 

Emissions (tons/yr)

[Total throughput (tons/yr) X Emissions Factor (lbs/ton)]/2000 (lbs/tons), 

where, 

• Total throughput is the total combined throughput of 7 composting facilities 

using the windrow method of composting; and, 

• The emissions factor is a variable dependant on the pollutant and process 

phase. 

Emission Reductions (tons/yr)

[Emissions (tons/yr) X Control Efficiency %] 

where, 

• The emissions are a variable dependant on the pollutant and process phase; and, 

• Control Efficiency is the result of the capture efficiency multiplied by the 

destruction efficiency of the control device. Control Efficiency is a variable 

dependant on the pollutant and process phase. 

Table 4-1 – Co-Composting Scenarios, provides a summary of the emission 

reductions for each of the control scenarios analyzed for co-composting. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 3 March 2002 

Table 4-1 – Co-Composting Scenarios 

Ammonia 

Scenario 

 Composting 

Method 

Uncontrolled 

Emissions 

(tons/yr) 

Over-all Control 

Efficiency % 

Emission Reductions

(tons/yr) 

Total ER

(tons/yr) 

 Active Curing Active Curing Active Curing Active Curing 

1 Enclosed 

ASP 

Enclosed 

ASP 654.98 654.98 75 75 491.24 491.24 982.47 

2 Enclosed 

ASP 

Negative 

Pressure 

ASP 654.98 654.98 75 19 491.24 122.81 614.05 

3 Negative 

Pressure 

ASP 

Negative 

Pressure 

ASP 654.98 654.98 25 19 162.11 123.23 285.34 

VOC 

1 Enclosed 

ASP 

Enclosed 

ASP 636.65 159.16 90 90 572.99 143.24 716.23 

2 Enclosed 

ASP 

Negative 

Pressure 

ASP 636.65 159.16 90 23 572.99 35.81 608.80 

3 Negative 

Pressure 

ASP 

Negative 

Pressure 

ASP 636.65 159.16 30 23 188.70 36.21 224.92 

Greenwaste-Composting 

AQMD staff analyzed the following three control scenarios for the greenwastecomposting sector of the composting industry: 

Scenario 1

• Enclosure of the active and curing phases of the process and the utilization of an 

Aerated Static Pile (ASP) system; 

• Venting of emissions to a control device (biofilter). 

Scenario 2

• Enclosure of the active phase of the process and the utilization of an ASP system; 

• No control for the curing phase of the process; and, 

• Venting of the active composting emissions to a control device (biofilter). 

Scenario 3

• Utilization of an ASP system under negative pressure for the active and curing 

phases of the process (no enclosure); and, 

• Venting of emissions to a control device (biofilter). 

The following assumptions were made to analyze the previously described control 

scenarios for greenwaste-composting: 

1. The ten largest facilities are open static piles windrow type operations and 

combined, these facilities have a total throughput of 819,461 tons/yr; 

2. The emission factor for ammonia for the active phase of the composting 

process is 0.83 lbs/ton greenwaste; 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 4 March 2002 

3. The emission factor for ammonia for the curing phase of the composting 

process is 0.02 lbs/ton greenwaste; 

4. The VOC emission factor for the active phase of composting is 3.44 lbs/ ton 

greenwaste; 

5. The VOC emission factor for the curing phase of composting is 0.4 lbs/ton 

greenwaste; 

6. The static windrow piles method of composting is assumed to be the baseline 

source of emissions, having no emissions capture efficiency (0%); 

7. The capture efficiency of negative-ASP during the active and curing phases of 

the process phase of the process is assumed to be 25%; 

8. Enclosure is assumed to mean total enclosure and therefore, having a capture 

efficiency of 100%; 

9. The ammonia destruction efficiency for biofiltration is assumed to be 75%; 

10. The VOC destruction efficiency for biofiltration is assumed to be 90% 

percent: and, 

11. No emission reduction benefit for resting pile emissions is assumed for an 

ASP. 

Emission reductions were calculated using the previously listed equations. Table 4-2 

– Greenwaste-Composting Scenarios, provides a summary of the emission reduction 

for the three scenarios evaluated for greenwaste-composting. 

Table 4-2 

Greenwaste Scenarios

Ammonia 

Scenario 

 Composting 

Method 

Uncontrolled 

Emissions 

(tons/yr) 

Over-all Control 

Efficiency % 

Emission Reductions

(tons/yr) 

Total ER

(tons/yr) 

 Active Curing Active Curing Active Curing Active Curing 

1 Enclosed 

ASP 

Enclosed 

ASP 

340.50 8.23 75 75 255.4 6.2 261.60 

2 Enclosed 

ASP 

No 

Control 

340.50 8.23 75 0 255.38 0 255.38 

3 Negative 

Pressure 

ASP 

Negative 

Pressure 

ASP 

340.50 8.23 19 19 63.97 1.54 65.51 

VOC 

1 Enclosed 

ASP 

Enclosed 

ASP 

1,411.22 162.55 90 90 1,270.16 147.50 1,417.66 

2 Enclosed 

ASP 

No 

Control 

1,411.22 162.55 90 0 1,270.28 0 1,270.28 

3 Negative 

Pressure 

ASP 

Negative 

Pressure 

ASP 

1,411.22 162.55 23 23 317.13 37.29 354.42 

Summary 

As illustrated in both Tables 4-1 and 4-2, full enclosure of active and curing piles would 

generate the greatest emission reductions with open ASP providing the least reductions. 

However, the emission reduction potential could be higher than the data presented in 

Tables 4-1 and 4-2 for all three scenarios, if additional emission reduction benefits from 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 5 March 2002 

ASP operations can be quantified. It may also modify the incremental difference 

between scenarios 2 and 3. 

COST-EFFECTIVENESS 

Affected Facilities 

The control scenarios analyzed affect composting and chipping and grinding facilities 

in the AQMD jurisdiction. The affected facilities mainly belong to SIC 4952 

(Sewerage System) and 4953 (Refuse System). Of these affected facilities, only 17 

composting facilities are required to install control equipment, and, therefore, would 

incur significant additional costs. Of the 17 composting facilities, ten facilities are 

greenwaste-only and the remaining seven are co-composting facilities. Three 

composting facilities (18%) are located in Los Angeles County, three facilities (18%) 

in Orange County, four facilities (23%) in Riverside County, and the remaining seven 

facilities (41%) are located in San Bernardino County. 

Small Business Impacts 

The AQMD defines a "small business" in Rule 102 as one which employs ten or 

fewer persons and which earns less than $500,000 in gross annual receipts. In 

addition to the AQMD's definition of a small business, the federal Small Business 

Administration (SBA), the federal Clean Air Act Amendments (CAAA) of 1990, and 

the California Department of Health Services (DHS) also provide their own 

definitions of a small business. 

The SBA's definition of a small business uses the criterion of either gross annual 

receipts (ranging from $0.5 million to $17 million, depending on industry type) or 

number of employees (ranging from 100 to 1,500). The SBA definitions of small 

businesses vary by 4-digit SIC code. The industries affected by the proposed Rule 

1133 mainly belong to SIC 4952 and 4953⎯sanitary and refuse systems 

(miscellaneous processes). For the facilities affected by the proposed rule, gross 

annual receipts of $5 million is the criterion below which a business is considered 

small under the federal SBA definition. The CAAA classifies a facility as a "small 

business stationary source" if it: (1) employs 100 or fewer employees, (2) does not 

emit more than ten tons per year of either VOC or NOx, and (3) is a small business as 

defined by SBA. The DHS definition of a small business uses an annual gross receipt 

criterion (ranging from $1 million to $9.5 million, depending on industry type) for 

non-manufacturing industries and an employment criterion of fewer than 250 

employees for manufacturing industries. 

Of the 17 affected composting facilities, ten have gross annual receipts and employee 

information reported in the 2000 Dun & Bradstreet database acquired by the AQMD. 

Based on the AQMD’s Rule 102 definition, only one of the ten facilities would be 

considered a small business. With the federal SBA’s definition, three facilities would 

be considered small businesses. With the CAAA’s, ten could be considered small 

businesses. Table 4-3 provides the range of the gross annual sales and number of 

employees for these facilities. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 6 March 2002 

Table 4-3 

Number of Facilities by Sales and Employees 

Gross Annual 

Sales (millions $) 

Number of 

Facilities 

 Number of 

Employees 

Number of 

Facilities 

Less than $0.5 1 5 to 9 2 

> $0.5 and < $1 1 10 to 19 0 

>$1 and < $2.5 3 20 to 49 6 

> $2.5 and < $5 2 50 and above 2 

> $20 and < $50 3 100 to 500 3 

Cost Assumptions 

Some of the control scenarios require active co-composting and greenwaste-only 

processes to be enclosed and to have forced aeration, either through an in-vessel or 

aerated static pile (ASP) system. Emissions from the enclosure must be vented to a 

biofilter or other control device that achieves a control efficiency of 75 percent 

reduction for ammonia and 90 percent reduction for VOC. 

Compliance costs of the control scenarios were estimated based on the cost of the 

building enclosures, ASP, and biofilters. The cost of building enclosures was 

estimated based on the enclosure area (square feet) required relative to the total 

annual throughput of an affected facility. It should be noted that total throughput 

includes feedstock (sewer sludge/manure) and bulking agent. In addition, for the 

building enclosure, two different structural designs were assumed: concrete and fabric 

structures. For concrete and fabric structures, estimated costs of $50 and $30 per 

square feet were assumed, respectively. These estimates include building structure, 

air exchanges and fire protection systems, and were based on City of Redlands and 

the IEUA RP-1 conceptual design plan. For the enclosure of active and curing, 1.5 

square feet per ton of annual throughput and for enclosure of active piles only, 0.75 

square feet per ton of annual throughput was used. These estimated were based on 

Inland Empire Utility Agency (IEUA) RP-1 conceptual design, IKEA (IEUA) site 

design, and city of Davenport design plans. 

The cost for ASP in the city of Columbus conceptual design and the city of 

Davenport’s plan was used. The annualized cost of ASP was estimated at $6.75 per 

ton of throughput. This estimate includes flooring, piping, and aeration equipment. 

The Biofilter estimate was derived based on biofilter surface required for emissions 

treatment. The biofilter cost was estimated at $12 per square feet of biofilter surface. 

This estimate was provided by Black and Veatch Company, and includes cost 

components such as biofilter fans, ducks, and biofilter media. 

It is assumed that the economic life of building enclosures, ASP, and biofilters is 15 

years each. Operating and maintenance cost for the total enclosure was assumed to 

be 10 percent of the total capital cost. For the biofilters, the cost of media change 

every three years is included in their operating cost. The total annual throughput of 

the affected facilities is estimated at 1,713,636 tons, of which 894,175 tons are from 

co-composting and the remaining 819,461 are from greenwaste only facilities. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 7 March 2002 

Compliance Costs 

Table 4-4 and 4-5 present annualized cost and cost effectiveness of the three 

scenarios for co-composting and greenwaste-only facilities. For co-composting 

facilities, cost-effectiveness ranges from $21,154 to $42,515 per ton of VOC 

reduction. The corresponding annualized costs of scenarios one, two, and three are 

estimated at $27.1 and $22 million, $19.9 and $17.3 million, and $12.9 million, 

respectively. 

The annualized cost of each scenario includes both annualized cost of capital and 

annual operating and maintenance costs (10 % of total annual cost). The total capital 

cost includes cost of building enclosure, ASP, and biofilter. The capital cost is 

annualized by multiplying total capital cost by a capital recovery factor (CRF) of 

0.090. The CRF 0.090 is based on a 15-year period (the assumed equipment lifetime) 

and with a 4 percent real interest rate. 

For the purpose of illustration, the total annualized cost of a typical facility with an 

annual throughput of 200,000 tons is estimated at $4,497,300, as shown below: 

Capital Cost 

Total Building Cost: $7,500,000 

Total ASP Cost: $14,250,000 

Total Biofilter Cost: $1,920,000 

Total Capital Cost: $23,670,000 

Operating Cost 

O & M Cost: 0.1 x($23,670,000) = $2,367,000 

Total Annualized Cost = Total Capital Cost x CRF (0.090) + O & M Cost 

= ($23,670,000 x 0.090) + $2,367,000 = $4,497,300 

For each scenario, cost-effectiveness is calculated based on both overall emission 

reductions and VOC emission reductions only for both concrete and fabric structure 

designs. The cost-effectiveness analysis uses the Discounted Cash Flow (DCF) 

method to compute the present value of the proposed rule’s costs over a 15-year period 

(the assumed equipment lifetime) with a 4 percent real interest rate, which gives the 

present value factor of 11.118. DCF cost effectiveness can then be calculated as: 

( )

Emission R ductions years

Capital Costs Annual O M Costs Cost Effectiveness

tons/yr e 15

& 11.118

×

+ × =
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 8 March 2002 

Table 4-4 

Co-Composting Annualized Cost and 

Cost-effectiveness by Scenario ($/ton) 

Scenarios Description 

Annualized Cost

(Millions $)

C-E for VOC Only C-E for VOC & 

Ammonia 

 

Concrete Fabric Concrete Fabric Concrete Fabric 

1 

Enclose* 

Active and 

Curing 

Piles 

+ASP + 

Biofilter 

$27.1 $22 $28,052 $22,779 $11,828 $9,604

2 

Enclose* 

Active Piles 

only 

+ASP + 

Biofilter 

$19.9 $17.3 $24,255 $21,154 $12,076 $10,531

3 Open ASP 

+ Biofilter $12.9 $42,515 $18,740

*Includes Static and Tipping Piles.

As with the co-composting, three scenarios representing three different levels of 

control were selected to analyze the effectiveness of the proposed rule on greenwasteonly facilities. 

Table 4-5 presents annualized cost and cost-effectiveness of the three scenarios for 

greenwaste-only facilities. Cost-effectiveness ranges from $8,929 to $24,726 per ton 

of VOC reduced. Cost-effectiveness ranges from $9,604 to $18,740 per ton of 

combined VOC and ammonia reduced. The corresponding annualized costs of 

scenarios one, two, and three are estimated at $24.8 and $20.1 million, $17.6 and 

$15.3 million, and $11.8 million, respectively. There is no building enclosure 

requirement for the scenario three. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 9 March 2002 

Table 4-5 

Greenwaste-Only Annualized Cost and 

Cost-effectiveness by Scenario ($/ton) 

Scenarios Description 

Annualized Cost

(Millions $)

C-E for VOC Only C-E for VOC & 

Ammonia 

 

Concrete Fabric Concrete Fabric Concrete Fabric 

1 

Enclose* 

Active and 

Curing 

Piles 

+ASP + 

Biofilter 

$24.8 $20.1 $12,988 $10,547 $10,962 $8,901

2 

Enclose* 

Active Piles 

only 

+ASP + 

Biofilter no 

Control on 

Curing 

$17.6 $15.3 $10,291 $8,929 $8,568 $7,434

3 Open ASP 

+ Biofilter $11.8 $24,726 $20,869

*Includes Static and Tipping Piles.

Due to lack of sufficient data at this time, PM10 emission reductions and additional 

emission reductions from ASP technology (i.e., lower pile emissions) have not been 

quantified for all scenarios. As a result, it is expected that emission reductions could 

be larger and control process would be more cost-effective than is currently 

established. PM10 emissions inventory as well as emission reductions will be further 

evaluated. 

Incremental Cost-effectiveness 

H&SC Section 40920.6, requires that incremental cost effectiveness be performed 

whenever more than one control option is available to meet emission reduction 

requirements for a proposed rule or amendment relating to ozone, carbon monoxide 

(CO), oxides of sulfur (SOx), oxides of nitrogen (NOx), and their precursors. 

Incremental cost effectiveness is defined as the difference in costs divided by the 

difference in emissions between one level of control and the next more stringent 

control. The incremental cost-effectiveness analysis related to the VOC portion of 

the proposed rule will be presented in the final staff report. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 10 March 2002 

Unquantified Savings 

Some control scenarios require active composting process to be enclosed and to have 

forced aeration either through an in-vessel or aerated static pile (ASP) system. This 

process provides a more precise control of oxygen and temperature conditions, and 

can greatly reduce odors and emissions by promoting optimal aerobic conditions. 

Furthermore, this process requires fewer spaces for active composting and reduces 

time required to produce final composting product. For example, the Los Angeles 

County Sanitation District (LACSD) composting study shows that with the ASP 

technology the actual surface area required for composting could be up to 60 percent 

less than the footprint required for active windrow composting piles. Therefore, ASP 

facilities sited could reduce capital investments in land acquisition. 

In addition, with proper operation, active composting from an enclosed ASP could be 

completed in far fewer days than the 45 to 60 days under traditional windrow 

composting. Therefore, the volume of finished compost product and revenue 

generated from selling them could possibly increase. To the extent it could occur, an 

enclosed ASP system could reduce even more emissions generated from this 

additional throughput. Since the capital cost of enclosed ASP systems would remain 

relatively constant during the process, more throughputs would make this process 

more cost-effective. 

Hauling Scenarios 

Staff has developed two additional scenarios to further evaluate the potential cost 

impact, which could incur as a result of the proposed rule. Scenario one assumes that 

the proposed rule would cause complete shutdown of all composting facilities in the 

district, and, as a result, one hundred percent of the biosolid and greenwaste materials 

are hauled away and dumped out of the state. This estimate was based on hauling 

1,713,636 tons per year of materials to landfills out of state. This estimate includes 

both transportation cost and tipping fees cost. Based on both LA County Sanitation 

District and the AQMD’s survey, hauling cost is estimated at $18 per ton. This 

estimate includes fuel cost, driver’s salary, benefits, food and depreciation of the 

vehicle. The tipping fees for outside of the state is assumed to be $20 per ton. Based 

on these assumptions, the total annual cost of hauling scenario is estimated at $38 per 

ton. The annual cost of this scenario is estimated at $65.1 million. 

Scenario two is similar to scenario one, but assumes that only 75 percent of the 

biosolids and greenwaste materials would be shipped out of the state and the 

remaining 25 percent would be hauled to the local landfills. The annual cost includes 

both transportation cost and tipping fees cost. Based on the Integrated Waste 

Management Board (IWMB) survey data (1995-2000), the average tipping fee at the 

local landfill is estimated at $35 per ton. The annual cost of this scenario is estimated 

at $67.5 million. 

According to the recent information received by staff, the projected cost of hauling 

waste is estimated at $63 per ton, which includes $33 per ton for transporting 

materials to out of state (Arizona) and $30 per ton for tipping fees charged by the 

landfills located outside of California. This could significantly increase the cost of 

the hauling scenarios described above. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 11 March 2002 

In response to stakeholders questions, AQMD staff also analyzed the transportation 

emissions impact from increased hauling. The [potential emissions increase from 

hauling scenario is estimated at 13 ton of VOC, 57 tons of CO, 290.5 tons of Nox, 

and 7.50 tons of PM10 (Diesel) per year. These emissions are estimated based on the 

ARB’s EMFAC 2001 emission factors from the above pollutants. The remaining 

assumptions are as follows: 

Total Throughput per year 1,713,636 

Load per Truck 23 tons 

Round trip Miles 400 

Number of truck Trip per year 74,506 

Total number of Miles per day 81,650 

Total Number of Miles per day (District) 40,825 (Based on GIS Analysis) 

Affordability Analysis 

For the purpose of evaluating of the financial impacts, staff has estimated the annualized 

cost per ton of throughput of the most likely control scenario, Scenario 2, for selected 

number of affected facilities. Furthermore, due to lack of financial information from 

these facilities, revenues from tipping fees and product sales were estimated and used as a 

surrogate to a facility’s total revenue. 

Table 4-6 and 4-7 present both annual compliance costs and revenues per ton of 

throughput for the selected co-composting and greenwaste-only facilities. 

Table 4-6 

Potential Cost Impacts of the Proposed Rule (Scenario 2) on 

Selected Co-Composting Facilities 

Facility Annual 

Throughput 

Status 

Annualized 

Control 

Costs 

Incremental

Costs 

Per ton of 

Throughput 

Surrogate Revenue 

From Tipping Fees 

and Product Sales 

per Year ($/ton)** 

A 365,000 Private $8,134,755 $22 $18,213,500

($40 and $30 )

B 200,500 Private $4,468,343 $22 $10,004,501

($40 and $30 )

C 250,000 Public/

Private

$5,571,750 $22 $7,475,000

($20 and $30)

**It was assumed that only 33% of co-composting materials would be converted to a final composting 

product. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 4 - 12 March 2002 

Table 4-7 

Potential Cost Impacts of the Proposed Rule (Scenario 2) on 

Selected Greenwaste-only Facilities 

Facility Annual 

Throughput 

Status 

Annualized 

Control 

Cost 

Incremental

Costs 

Per ton of 

Throughput 

Surrogate Revenue 

From Tipping Fees 

and Product Sales 

per Year ($/ton)** 

A 312,000 Private $6,717,017 $22 $13,728,000

($20 and $30 )

B 187,200 Private $4,030,210 $22 $7,675,200

($25 and $20 )

C 130,000 Private $2,798,757 $22 $3,640,000

($12 and $20 )

** It was assumed that only 80% of greenwaste-only materials would be converted to a 

final composting product. 

The annualized compliance costs of Scenario 2 is about 50 percent of the annual revenue 

received by both co-composting and greenwaste-only facilities. 

Financial Incentives 

The facilities affected by Proposed Rule 1133 may seek funding to help defray the 

cost of the proposed rule. For example, the California IWMB offers funding 

opportunities authorized by legislation to assist public and private entities in the safe 

and effective management of the waste stream. The Recycling Market Development 

Zone Revolving Loan Program (RMDZ) provides direct loans to businesses that use 

post-consumer or secondary waste materials to manufacture new products or that 

undertake projects to reduce the waste resulting from the manufacture of a product. 

Since 1998, the RMDZ program has provided financing totaling $2,146,875 (less than 

10 percent of the total funding) to five companies involved in composting and 

$682,000 to one company involved in mulching. The RMDZ loan program is driven 

by increased diversion from landfills and a development of markets for recycled or 

recycled content products. 

In addition to the RMDZ program, there are other potential sources of financial

assistance for affected facilities as follows: 

• Air Resources Board: Grant or loan programs regarding air quality 

• California Communities: Solid Waste/Recycling–Land, Building, and Equipment 

Loans 

• State Treasurers Office: Various bond financing and loan guarantee programs 

• California Technology, Trade and Commerce: Programs for small businesses 

• U.S. Small Business Administration: Various loans guarantee programs 

• AQMD Small Business Assistance: Various loans guarantee programs 
CHAPTER V 

 

RECOMMENDATIONS 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 5 - 1 March 2002 

INTRODUCTION 

This chapter discusses the following: 

9 AQMD staff Recommendations 

AQMD STAFF RECOMMENDATION 

Based on information from this report, AQMD staff is recommending that AQMP 

Control Measure WST-2 – Emission Reductions from Composting and Related 

Operations, be implemented in two phases. The first phase would consist of an 

adoption of a fact-finding rule that would have the elements listed below. The first 

phase would also include control requirements for new co-composting facilities with 

total design capacity of 100,000 tons per year. The second phase would consider 

composting control technologies for new and existing facilities based on the results of 

additional technical work described below. AQMD staff proposes to bring the first 

phase rule to the Board for consideration in mid-year 2002. 

Co-Composting 

As described in this report, co-composting facilities are major sources of VOC and 

ammonia emissions (e.g., a 100,000 ton/year total throughput facility has annual 

emissions of 89 tons/year VOC and 147 tons/year ammonia). Based on local 

community concerns and industry studies, siting of large co-composing facilities in 

urban areas now requires active consideration of enclosed and controlled facilities to 

address public health and nuisance concerns. Enclosed ASP or in-vessel systems 

with control equipment, while feasible and effective at significantly reducing 

emissions, are costly. Based on industry comment and the staff’s analysis, there may 

be additional emission reductions associated with ASP systems that have not been 

quantified in this report (e.g., reduced pile emissions due to forced aeration). 

Additional testing of ASP systems, such as that proposed by Southern California 

Association of POTWS (SCAP), would allow the emission reduction potential of all 

control scenarios to be refined. Also, additional operational and cost information for 

an enclosed ASP system will be available subsequent to the opening of IEUA's’RP-1 

facility in 2003. This information would allow this report’s conservative costeffectiveness analysis to be refined. PR 1133 would require that new co-composting 

facilities above 100,000 tons/year total throughput meet the Scenario 2 control 

requirements (i.e., enclosed active composting with controls) and all existing 

operations and new operations under 100,000 tons/year of total throughput would 

meet certain registration and annual reporting requirements. Specifically: 

• Scenario II control requirements for new facilities with total throughput 

designed capacity of 100,000 tons per year; 

9 Enclosure and ASP for the active phase of the process with emissions 

vented to a bio-filtration system; 

9 Open ASP for the curing phase of the process with emission vented to a 

bio-filtration system; 

• One-time registration with AQMD; 

• Annual reporting requirements; and, 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 5 - 2 March 2002 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions. 

This proposal is consistent with Best Available Control Technology practices and is 

designed to address potential public nuisance and emission issues. AQMD staff is 

aware that three out of four existing facilities with designed capacities of 100,000 

tons per year or more, are planning to close operations at their existing sites and move 

to other locations where they are expected to meet or exceed Scenario II control 

requirements. Furthermore, it is recommended that the AQMD staff take the 

following actions: 

• Establish a Composting Technical Advisory Group (CTAC): 

AQMD staff will continue to evaluate all source testing and other studies currently 

under development including, but not limited to, the SCAP study and testing 

conducted by the Integrated Waste Management Board. As part of this evaluation 

process, AQMD staff is recommending that a Composting Technical Advisory 

Committee (CTAC) be formed to address the technical concerns of this sector of the 

composting and related operations industry. The TAC would include members of the 

regulated community, staff from the Integrated Waste Management Board and 

AQMD, representatives from sanitation district and utility agencies. 

• Report to the AQMD Stationary Source Committee in six months on findings 

from the SCAP study. The SCAP study is designed to test the effectiveness of 

an open ASP system and some select operating parameters and is expected to 

be completed by June 2002. Staff will summarize the technical findings and 

provide recommendations as appropriate in seeking cost-effective control 

opportunities. 

• Provide technical assistance to local or state jurisdiction on air quality issues 

during permitting or the preparation of CEQA documents. During this 

rulemaking, the staff has obtained a great deal of information on composting 

air emissions and it would be beneficial to the permitting or lead agency to 

give adequate air quality consideration in its decision-making. It also 

provides an opportunity to evaluate emission reduction potential on a case-bycase basis. 

Greenwaste Composting 

As described in Chapters 2 and 4 of this report, the greenwastes industry represents a 

significant source of VOC emissions and its control options in general are considered 

cost-effective even without taking accounting for additional reduction potential from 

an ASP system. However, the affordability analysis and potential increase in tipping 

fees indicate that these controls are infeasible at this time without government grants 

to help finance controls. As a result, the staff is proposing minimal requirements on 

the industry at this time and the proposed requirements would primarily track its 

operations and emissions inventory and to claim SIP reductions should site-specific 

controls be implemented. The following summarizes the proposed requirements: 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 5 - 3 March 2002 

• One-time registration 

• Annual reporting requirements 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions 

In light of the fact that there are cost-effective control options for this industry that 

are not yet affordable, AQMD staff is recommending that, through the District’s 

Legislative Committee, special funding from the state legislature be sought to 

implement state of the art composting methods, including but not limited to, enclosed 

ASP. AQMD staff will work with the CIWMB and CARB to seek additional funding 

and/or make existing funding directed more towards air quality spending. 

Chipping and Grinding Requirements 

• One-time registration; 

• Compliance with all applicable AQMD rules, regulations and permit 

conditions; 

• Holding time restrictions by source of unprocessed materials and by the end 

usage of chipped and ground materials; and 

• PM10 controls to prevent visible PM10 emissions over the property line 

during operations and from processed material piles. 

Exemptions 

• Portable chipping and grinding 

• Community composting 

• Agricultural composting 

• Nurseries 

• Small Operations (throughput threshold to be determined) 

Registration and Annual Reporting Requirements 

The one time registration requirement will, at a minimum, require facility owners 

and/or operators to provide the following information: 

9 Facility name; 

9 Facility location and mailing address; 

9 Facility legal owner; 

9 Facility operator; 

9 Facility contact person; 

9 Facility IWMB identification number and contact person; 

9 LEA identification number and contact person; 

9 Facility designed capacity (throughput); 

9 Feedstock description; 

9 Composting process description; 

9 Products produced; 

9 Customers profile; 

9 Tipping fee schedule; and, 

9 Number of employees. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 5 - 4 March 2002 

The annual reporting requirements would require the following information: 

9 Update of registration information, as pertinent; 

9 Annual actual throughput; 

9 Number of enforcement actions against the facility by enforcing agency; 

Annual Status Report 

The information received from the co-composting and greenwaste facilities and their 

emission estimates will be summarized and presented as an annual status report to the 

AQMD Stationary Source Committee. As part of this report, funding opportunities, 

composting technology, progresses in emission reductions will also be included. 
CHAPTER VI 

 

PUBLIC OUTREACH 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 6 - 1 March 2002 

INTRODUCTION 

This chapter discusses the following: 

9 Public Outreach 

PUBLIC OUTREACH 

The public outreach efforts for Proposed Rule 1133 – Composting and Related 

Operations, included public meetings, focused presentations, and site visits. The 

meetings were well attended. In general, the average number of people in attendance 

for each of the meetings range from 60 to 80 people. Following is chronological 

listing of the public meetings. 

♦ Public Consultation Meeting, October 5, 2000 

♦ Proposed Rule 1133 Working Group Meeting, August 22, 2001 

♦ Public Workshop, September 5, 2001 

♦ Proposed Rule 1133 Working Group Meeting, September 28, 2001 

♦ Proposed Rule 1133 Working Group Meeting, January 15, 2002 

♦ Proposed Rule 1133 Working Group Meeting, February 19, 2002 

Focused presentation on Proposed Rule 1133 where given to the following 

entities: 

♦ Orange County League of Cities 

♦ San Gabriel Valley COG Solid Waste Committee 

♦ California League of Cities – Environmental Quality Committee 

9 Membership includes all cities in the State of California 

♦ San Bernardino County Solid Waste Advisory Task Force 

♦ California Contract Cities Association, Legislative Committee 

♦ SCAG Solid Waste Task Force 

♦ Los Angeles County Solid Waste Management Committee Integrated Waste 

Management Task Force 

♦ AQMD’s Ethnic Community Advisory Group 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 6 - 2 March 2002 

♦ AQMD’s Local Governments and Small Business Advisory roup 

♦ AQMD’s Stationary Source Committee 

AQMD staff conducted site visits to the following facilities: 

♦ Aguinaga Fertilizer 

♦ B. P. Hauling 

♦ California Biomass 

♦ Community Recycling & Resource Recovery, Inc. 

♦ Empire Utilities Agency Composting Facility 

♦ Inland Empire Composting 

♦ Leisure World 

♦ Los Angeles City – Archrorage 

♦ Los Angeles City – Griffith Park 

♦ Los Angles City – VanNorman 

♦ R & S Dumping Service 

♦ Rancho Las Virgenes Composting Facility 

♦ River Ranch Recycling Organics 

♦ Salado Creek – Coachella Landfill Composting 

♦ Sierra Soil Company 

♦ Synagro 

♦ Tierra Verde Industries 

♦ Whittier Fertilizer 

In addition to the site visits, AQMD staff has met numerous times with industry and 

sanitation district(s) representatives, individually and in groups, to address specific 

rule proposal issues and discuss research plans. 

Following is a list of all the cities and governmental agencies that to date have been 

active in the rulemaking process for Proposed Rule 1133: 

♦ City of Burbank 

♦ City of Cerritos 

♦ City of Chino 

♦ City of Chino Hills 

♦ City of Colton 

♦ City of El Segundo 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 6 - 3 March 2002 

♦ City of Glendale 

♦ City of La Canada-Flintridge 

♦ City of Los Angeles 

♦ City of Newport Beach 

♦ City of Palm Springs 

♦ City of Pasadena 

♦ City of Pico Rivera 

♦ City of Redlands 

♦ City of San Diego 

♦ City of San Marino 

♦ City of Santa Fe Springs 

♦ City of Upland 

♦ City of West Covina 

♦ City of Whittier 

♦ Eastern Municipal Water District 

♦ Inland Empire Utilities Agency 

♦ Las Virgenes Municipal Water District 

♦ Los Angeles City Dept. of Water & Power 

♦ Los Angeles County – Dept. of Parks & Recreation 

♦ Los Angeles County – Public Works Dept. 

♦ Los Angeles County Arboretum & Botanical Gardens 

♦ Los Angeles County DPW 

♦ Los Angeles County LEA 

♦ Los Angeles County Sanitation District 

♦ Municipal Water District 

♦ Orange County Council of Governments 

♦ Orange County Integrated Waste Management 

♦ Orange County Sanitation District 

♦ Riverside County Environmental Health 

♦ Riverside County Waste Management Dept. 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 6 - 4 March 2002 

♦ San Bernadino County LEA 

♦ San Bernadino County Solid Waste Management District 

♦ Southern California Alliance of Publicly Owned Treatment Works 

♦ Southern California Association of Governments 

♦ Ventura County Air Pollution Control District 

♦ Ventura County LEA 

♦ Western Riverside Council of Governments 
 

REFERENCES 

 
Technology Assessment for Proposed Rule 1133 

Proposed Rule 1133 REF - 1 March 2002 

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Black & Veatch Corp. Operation and Maintenance Manual for Rancho Compost Facility

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Black & Veatch Corporation. Biofiltration for Odor Control.

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Inland Empire Utilities Agency. Chino Basin Organics Management Strategy Business 

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Rosenfeld, Paul, Ph.D. Synagro’s Odor Control and Pathogen Reduction Pilot Program. 

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Proposed Rule 1133 REF - 2 March 2002 

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SCEC. Compliance Source Testing Plan for Las Virgenes Municipal Water District. 

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