EPA/600/R-14/039 / August 2014 / www.epa.gov/researc
United States
Environmental Protection
Agency
Best Management Practices to
Prevent and Control Hydrogen
Sulfide and Reduced Sulfur
Compound Emissions at
Landfills That Dispose of
Gypsum Drywall
Office of Research and Development
National Risk Management Research Laboratory
Land Remediation and Pollution Control Division
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EPA/600/R-14/039 BMP to Prevent and Control H2S and Reduced
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The U.S. Environmental Protection Agency (U.S. EPA) through the Office of Research and Development
funded and managed the research described here under contract order number: EP-W-09-004 to RTI
International in Research Triangle Park, North Carolina. It has been subject to the Agency's review and
has been approved for publication as a U.S. EPA document. Use of the methods or data presented in this
manual does not constitute endorsement or recommendation for use. Mention of trade names or
commercial products does not constitute endorsement or recommendation.
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Foreword
The U.S. Environmental Protection Agency (U.S. EPA) is charged by Congress with protecting the
Nation's land, air, and water resources. Under a mandate of national environmental laws, the Agency
strives to formulate and implement actions leading to a compatible balance between human activities and
the ability of natural systems to support and nurture life. To meet this mandate, U.S. EPA's research
program is providing data and technical support for solving environmental problems today and building a
science knowledge base necessary to manage our ecological resources wisely, understand how pollutants
affect our health, and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investigation
of technological and management approaches for preventing and reducing risks from pollution that
threaten human health and the environment. The focus of the Laboratory's research program is on
methods and their cost-effectiveness for prevention and control of pollution to air, land, water, and
subsurface resources; protection of water quality in public water systems; remediation of contaminated
sites, sediments, and ground water; prevention and control of indoor air pollution; and restoration of
ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that
reduce the cost of compliance and to anticipate emerging problems. NRMRL's research provides
solutions to environmental problems by: developing and promoting technologies that protect and
improve the environment; advancing scientific and engineering information to support regulatory and
policy decisions; and providing the technical support and information transfer to ensure implementation
of environmental regulations and strategies at the national, state, and community levels.
This publication has been produced as part of the Laboratory's strategic long-term research plan. It is
published and made available by U.S. EPA's Office of Research and Development to assist the user
community and to link researchers with their clients.
Cynthia Sonich-Mullin, Director
National Risk Management Research Laboratory
in
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Table of Contents
Abbreviations, Acronyms, and Initialisms vi
1. Introduction and Background 1
1.1 Issue Description and Report Objectives 1
1.2 Intended Audience 1
1.3 Report Organization 1
2. Fundamentals 2
2.1 Basics of H2S 2
2.2 H2S Regulatory Standards and Health Effects 2
2.3 H2S Formation in Landfills 4
2.4 Factors Impacting Emission of LFG 6
2.5 Composition of Waste Disposed of in C&D and MSW Landfills 8
2.6 H2S at C&D Debris Landfills 10
2.6.1 Factors Contributing to H2S Formation and Emission at C&D Landfills 10
2.6.2 H2S Concentrations Measured at C&D Landfills 11
2.7 H2S at MSW Landfills 16
2.7.1 Factors Contributing to H2S Formation and Emission at MSW Landfills 16
2.7.2 H2S Concentrations at MSW Landfills 17
2.8 Considerations for Other Reduced Sulfur Compounds 22
3. Methods to Prevent and Control H2S Emissions 23
3.1 Methods to Prevent H2S Formation 23
3.1.1 Diversion of Drywall and Limiting SO42" Content of RSM 23
3.1.2 Moisture Control 24
3.1.3 Bacterial Inhibition 25
3.2 Methods to Control H2S Emission 25
3.2.1 Leachate Management 25
3.2.2 Cover Soil and Amendments 26
3.2.3 Capping Systems 27
3.2.4 Odor Neutralizers 28
3.2.5 LFG Collection and Treatment 28
4. Site Investigation and Monitoring Techniques 31
4.1 Site Inspection Procedure Considerations 31
4.2 H2S Monitoring Techniques 32
5. BMP Framework to Manage H2S Emissions From Disposal of Gypsum Drywall 35
6. References 37
Appendix A - State and Federal Exposure Limits for H2S
IV
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List of Figures
Figure 2-1. Odor Threshold Ranges Reported by Different Sources 3
Figure 2-2. Illustration Indicating Common Landfill Processes and Examples of Areas Where
H2S May Be Sampled 8
Figure 2-3. Mass-Based Discarded C&D Debris Composition Based on Reported Data From
Seven States (adapted from Staley and Barlaz, 2009) 9
Figure 2-4. Discarded MSW Composition by Mass (adapted from Staley and Barlaz, 2009) 10
Figure 2-5. Reported H2S Concentrations Measured Within Landfilled C&D Waste or in an LFG
Well at a C&D Landfill (#1-10: Lee et al. (2006), #11: Rizzo and Associates
(2002), #12: Degner (2008)) 12
Figure 2-6. Reported H2S Concentrations Measured at the Surface of 11 C&D Landfill Sites in
Florida(#1-10: Lee etal. (2006), #11: ATSDR(2007)) 13
Figure 2-7. Compilation of Ambient Air H2S Measurements Near C&D Landfills (#1: ATSDR
(2007), #2: TetraTech(2004),and#3: Cooper etal. (2011)) 15
Figure 2-8. H2S Concentrations Measured in LFG at MSW Landfills (#1: U.S. EPA (1998b), #2:
Tennant (2012), #3 - 7: U.S. EPA (2007), #8: Capenter and Bidwell (1996), and #9:
Carlton et al. (2005)) 19
Figure 2-9. Ambient, Perimeter, and Offsite Measured or Modeled Concentrations of H2S at
MSW Landfills (#1: OEPA, 2006' #2: ATSDR, 2009; and #3: Heaney et al., 2011) 21
Figure 5-1. Framework for Developing a BMP Guide for Managing H2S at C&D or MSW
Landfills 35
List of Tables
2-1. Health Effects and Approximate Corresponding H2S Concentration, as Summarized
by WHO (2003) 4
2-2. Examples of State and Regional H2S Gas Standards, Guidelines, and Screening
Levels 4
2-3. Summary of Factors that Contribute to the Production of H2S in Landfills 5
2-4. Transport Mechanisms and the Factors That Impact LFG Emission (U.S. EPA 1997) 6
2-5. Conditions That May Promote H2S Production at C&D Landfills 11
2-6. Calculated Modeled Minimum Nuisance Odor Buffer Distances Based on H2S
Measurements Collected at a Florida C&D Landfill (adapted from Cooper et al.,
2011) 14
2-7. Conditions That May Promote H2S Production at MSW Landfills 17
2-8. Summary of H2S Concentration Data in MSW LFG Reported in the Draft
Compilation of Air Pollutant Emission Factors for MSW Landfills (U.S. EPA, 2008) 18
2-9. Reported H2S Measurement Data From Five MSW Landfills (U.S. EPA, 2007) 18
2-10. Summary of Measured RSC Concentrations From MSW LFG (U.S. EPA, 2008) 22
3-1. Summary of and Discussion of Moisture Control and Cover Soil Use Techniques to
Minimize the Production and Emissions of H2S 24
3-2. Summary of Treatment Technologies to Reduce H2S Concentrations in Collected
LFG 30
4-1. Examples of H2S Monitoring Devices, Applications, and Limitations 33
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CH4
Abbreviations, Acronyms, and Initialisms
ADC Alternative Daily Cover
AEGL Acute Exposure Guideline Level
ATSDR Agency for Toxic Substances and Disease Registry
BMP Best Management Practice(s)
°C Degrees Celsius
C&D Construction and Demolition
Ca Calcium
CaSO4 Calcium Sulfate
CDC Centers for Disease Control and Prevention
CH2O Formaldehyde
CH3SH Methyl Mercaptan
(CH3)2S Dimethyl Sulfur
(CH3)2S2 Dimethyl Disulfide
(CH3)2S3 Dimethyl Trisulfide
C3H§S Isopropyl Mercaptan
Isobutyl Mercaptan
Methane
Tert-Butyl Mercaptan
CO2 Carbon Dioxide
COD Chemical Oxygen Demand
COS Carbonyl Sulfide
CS2 Carbon Disulfide
GCCS Gas Collection and Control System
H2S Hydrogen Sulfide
LFG Landfill Gas
MoO42" Molybdate
MSW Municipal Solid Waste
mV Millivolt
(iL/L Microliters per Liter
N2 Nitrogen
nL/L Nanoliters per Liter
RSC Reduced Sulfur Compound
RSM Recovered Screen Material
S° Elemental Sulfur
SO2 Sulfur Dioxide
SO42- Sulfate
SRB Sulfate Reducing Bacteria
U.S. United States
U.S. EPA United States Environmental Protection Agency
WHO World Health Organization
WWTP Wastewater Treatment Plant
VI
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1. Introduction and Background
1.1 Issue Description and Report Objectives
Hydrogen sulfide (H2S) gas can be emitted from both construction and demolition (C&D) debris and
municipal solid waste (MSW) landfills. H2S emissions may be problematic at a landfill as they can cause
odor, impact surrounding communities, cause wear or damage to landfill gas (LFG) collection and energy
utilization components, or contribute to the formation of explosive conditions. H2S emissions at landfills
have often been attributed to the disposal of gypsum drywall, though other sources such as sulfur-
containing industrial wastes and biosolids from municipal wastewater treatment facilities can also
contribute to H2S production. Addressing problems from H2S emissions at landfills can be costly and
time consuming for landfill owners and operators. Several years of operational experience and research
efforts have identified several key pieces of information regarding the conditions that can cause H2S
production, factors that result in H2S production at landfills, and strategies to prevent these conditions
from occurring and to minimize the release of H2S to the surrounding environment when it is produced.
The U.S Environmental Protection Agency (U.S. EPA) Office of Research and Development, in
coordination with U.S. EPA Region 5, commissioned the development of a document designed to provide
landfill owners and operators with guidance on pertinent subject matter associated with H2S production,
emissions, prevention, and control at landfill sites. A previous effort (U.S. Environmental Protection
Agency [U.S. EPA], 2006b) focused on practices to prevent and control H2S emissions from C&D
landfills that accept pulverized gypsum debris in Ohio. This document expands the scope of this
previously developed guidance by consolidating additional landfill operational and research information
from a broader knowledge base (both C&D and MSW landfills), including additional information
regarding the science of H2S formation and control, the results of case studies with field and laboratory
measurement of H2S, and updated best management practices (BMPs).
1.2 Intended Audience
This report provides regulatory agencies, landfill owners and operators, and other interested parties with
information regarding the science of H2S production and emissions at landfill sites, and information on
BMPs to prevent and control these emissions. Emission levels are discussed in the context of published
health and safety standards and health-based or nuisance-based thresholds.
1.3 Report Organization
This report is organized into six sections. Section 1 presents the objectives of this report and describes
the report organization. Section 2 provides the fundamentals of H2S generation, related emission or
exposure standards, measured levels at C&D and MSW landfills, and information regarding production
and emission of other reduced sulfur compounds (RSCs). Section 3 presents a review of measures to
prevent and control the formation and/or emission of H2S from C&D and MSW landfills. Section 4
describes site investigation and monitoring techniques for H2S. Section 5 includes a framework that
landfill owners and operators can use to develop a BMP guide for their facility. Section 6 provides a list
of references cited in the report.
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2. Fundamentals
2.1 Basics of H2S
H2S (CAS #7783-06-4) is a poisonous, irritating, flammable, and colorless gas, with a characteristic
rotten-egg-like odor detectable by humans at low concentrations and a sweet odor at higher
concentrations. H2S (also known as hydrosulfuric acid, sewer gas, sulphuretted hydrogen, hepatic gas,
sour gas, and stink damp) is naturally occurring and found in crude petroleum, natural gas, volcanic gases,
and hot springs. There are also anthropogenic (man-made) sources of H2S gas, such as food processing,
coke ovens, paper manufacturing mills, tanneries, solid waste disposal facilities, petroleum refineries, and
waste water treatment plants (WWTPs). H2S gas is slightly heavier than air (specific gravity of 1.189)
and may accumulate in enclosed, poorly ventilated, and low-lying areas. When released into the
environment, H2S has been observed to persist for approximately 18 hours (Agency for Toxic Substances
and Disease Registry [ATSDR], 2006a) and up to 42 days, typically persisting longer in cold weather
(Bottenheim and Strausz, 1980). In the atmosphere, H2S transforms into sulfur dioxide (SO2) and/or
sulfuric acid (H2SO4>.
The explosive limit of H2S in air ranges from 4.3 to 46% (43,000 (iL/L to 460,000 (iL/L) (Centers for
Disease Control and Prevention [CDC], 2000). It has an autoignition temperature of 260 °C, a National
Fire Protection Association (NFPA) fire and health rating of 4, and a reactivity rating of 0 (scale 0-4)
(CDC, 2000). The water solubility limit of H2S is relatively high, with an equilibrium concentration of
4,132 mg/L at 20 °C (World Health Organization [WHO], 2003).
2.2 H2S Regulatory Standards and Health Effects
The lowest detectable concentration of H2S by humans has been examined by several investigators.
Amoore (1985) conducted a literature review of 26 H2S-related odor studies and found a median odor
detection threshold of 0.008 (iL/L (by volume). Figure 2-1 displays reported odor threshold ranges
reported by several different sources; differences in odor detection levels are primarily attributed to
differences in individual olfactory systems and sensitivity.
The detectable concentration of H2S does not necessarily equate to that of a nuisance level, although
Amoore (1985) indicated that five of the studies reported a nuisance-level concentration of 0.04 (iL/L,
approximately five times the detectable odor threshold. Mean atmospheric (i.e., ambient) H2S
concentrations in the United States reportedly range between 0.00071 (iL/L and 0.066 (iL/L (U.S. EPA,
2010a). Close proximity to a natural or anthropogenic source of H2S may produce ambient H2S
concentrations greater than the ambient mean.
Humans may not detect H2S at high concentrations due to olfactory fatigue (which may occur at
approximately 100 (iL/L with a 2- to 15-minute exposure) and olfactory paralysis (reported at
approximately 150 (iL/L) (Beauchamp, 1984; U.S. EPA, 2010a). Thus, odor is not always a reliable
indicator of the presence of H2S and may not provide adequate warning of hazardous concentrations.
H2S affects the body if inhaled or comes in contact with the eyes, skin, nose, and throat (Beauchamp,
1984, ATSDR 2006a, ATSDR 2006b, ATSDR 2006c). Respiratory protection can be used to prevent
inhalation if sufficient engineering controls are not available; a self-contained breathing apparatus and
supplied airline respirators (both supply a clean source of breathable air rather than purifying ambient air)
are considered acceptable protection from H2S (Kalusche, 2004).
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Iowa State University (2004)
Amoore (1985)
I
Collins and Lewis (2000)
ATSDR (2006)
I • •—'
Cooper etal. (2011)
o.oooi
o.ooi o.oi
H2S Odor Threshold Range (\i\Jl)
0.1
Figure 2-1. Odor Threshold Ranges Reported by Different Sources
Currently, there are no enforceable federal standards for offsite H2S gas emissions from landfills, or H2S
monitoring requirements specific to landfills. However, health effects due to H2S exposure have led to
the development of H2S workplace standards, which are typically expressed as a concentration and
referenced to an exposure time limit. Nuisance standards and health-based guidelines for human
exposure to H2S in the United States have been developed by numerous agencies and organizations.
Individual nuisance or health effects from H2S exposure vary depending on:
• exposure duration
• exposure concentration
• individual factors (e.g., asthmatics).
H2S blocks the oxidative process of tissue cells, reduces the oxygen-carrying capacity of blood, depresses
the central nervous system, and causes respiratory failure and asphyxiation in high concentrations
(Kalusche, 2004). At acute, lower-level concentrations, nausea, fatigue, loss of appetite, headaches, and
irritation can occur (WHO 2003). The reported effect of low-level, long-term H2S exposure in humans
has been mixed in the technical literature. For example, Kalusche (2004) reports effects such as eye
irritation, headache, photophobia, and blurred vision from long-term, low-level exposure. However, the
WHO (2003) stated that"... effects in human populations exposed for long periods to low levels of (H2S)
cannot serve as a basis for setting tolerable concentrations because of either co-exposure to several
substances or insufficient exposure characterization." WHO (2003) states that insufficient data on
possible carcinogenicity of H2S exists, and the compound has not been classified as a carcinogen
(ATSDR, 2006b). WHO (2003) summarized human health effects at variable H2S concentration levels
based on acute exposure scenarios, shown in Table 2-1.
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Table 2-1. Health Effects and Approximate Corresponding hhS Concentration, as Summarized by
WHO (2003)
Health Effect
No Observed Adverse Effect Level
Odor threshold
Bronchial constriction in asthmatic individuals
Eye irritation
Fatigue, loss of appetite, headache, irritability, poor memory,
dizziness
Olfactory paralysis
Respiratory distress
Death (likely a result of respiratory failure/arrest)
H2S Concentration (uL/L)
0.0014
0.007
2
4-21
20
>100
>400
>500
Acute Exposure Guideline Levels (AEGLs) (U.S. EPA, 2010a) for H2S have been developed and are
intended to describe the risk to humans that would result from once-in-a-lifetime, or rare, exposure to
airborne chemicals. The AEGLs for H2S were established based on a three-tiered system (level 1, level 2,
and level 3) that acknowledges the severity of expected health effects. Additionally, many other agencies
have published their own guidelines, screening levels, or health-based levels for H2S, which are detailed
in Appendix A of this report.
Some U.S. EPA regions and states have developed or adopted H2S air quality standards. Some examples
of these standards are included in Table 2-2. This list is not exhaustive and is not intended to encompass
all regional, state, or local H2S standards, guidelines, and screening levels. Additionally, the standards
may not apply to all areas in the region, state, or municipality.
Table 2-2. Examples of State and Regional H2S Gas Standards, Guidelines, and Screening Levels
Standards, Guidelines and Screening
Level Description
California Ambient Air Quality Standard
Maine Ambient Air Guidelines
Minnesota Ambient Air Quality Standards
(7009.0080- applies to property boundary,
primary standards)
Montana Ambient Air Quality Standards
(17.8.214)
New Mexico (20.2.3.1 10)
New York Ambient Air Quality Standards (257-
10.3)
Pennsylvania Ambient Air Quality Standards
U.S. EPA Region 9 Regional Screening Levels
(Also used by U.S. EPA Region 3 and 61
Concentration (uL/L)
0.03 - 1 hour average
0.03 - 30 minute average
0.001 - 1 year average
0.05 - 30 minute average not to be exceeded > 2
per year
0.03 - 30 minute average not to be exceeded > 2
in any 5 consecutive days
0.05 - 1 hour average not to be exceeded > once
year
times
times
per
0.01 - 1 hour average
0.01 - 1 hour
0.005 -24 hour
0.1 - 1 hour
0.0015 Residential Air
0.0063 Industrial Air
Note: ' Regional Screening Levels are risk-based target levels developed by guidance from the U.S. EPA Superfund program
that are used for Superfund sites. They are generic screening levels considered by U.S. EPA to be protective for humans
(including sensitive groups) over a lifetime.
2.3 H2S Formation in Landfills
H2S is generally formed in a landfill environment through the reduction of sulfate (SC>42~) Sulfate-
reducing bacteria (SRB) causing SO42" reduction to H2S are commonly observed in groundwater,
wastewater treatment plants, and sewers. Additionally, H2S production is attributed to hydrolysis of
sulfur-containing minerals (e.g., FeS2) in natural sources such as volcanoes and hot springs (ATSDR,
2006b).
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The reduction of SC>42 represents the primary generation mechanism in landfills; SC>42 may be present
from gypsum or other waste sources in the landfill (e.g., WWTP sludge), though the mass of reducible
sulfur minerals in drywall far exceeds that typically present in WWTP sludge. Gypsum is hydrated
calcium sulfate (CaSC>4 *2H2O) and is the major component of gypsum drywall panels, which normally
consists of 90% (by weight) gypsum and 10% backing paper. Gypsum drywall is also known as
plasterboard, gypsum board, gyproc, gib board, sheetrock, and wallboard, and hereafter referred to in this
report as gypsum drywall.
Gypsum drywall is a component of C&D waste and can be disposed of in C&D landfills or MSW
landfills, where it can arrive in bulk form or in size-reduced (pulverized or fine) form. Gypsum may also
be present in landfills (particularly MSW landfills) that accept screened, fine-grained material from C&D
recycling operations, which is typically referred to as recovered screen material (RSM). RSM is typically
sized from 3/8" to 2" or more and can contain a varying amount of size-reduced gypsum (the degree of
gypsum is largely dependent on the practices of the C&D recycler to remove gypsum prior to processing
the C&D at its facility). There are several contributing factors that may result in the production of IrkS in
landfills. These factors are summarized in Table 2-3.
Table 2-3. Summary of Factors that Contribute to the Production of hhS in Landfills
HhS Formation
Factor
SO42 Source
Moisture
Organic Matter
Anaerobic
Conditions
pH Conditions
Temperature
Conditions
Discussion
Sources of reducible sulfur in landfills may include gypsum drywall, WWTP sludges, or
other residential, commercial, or industrial wastes (e.g., auto shredder fluff impacted by
lead-acid batteries). Gypsum may be present in larger pieces of drywall or size-reduced
drywall, and may be present in fine particles contained in RSM.
Moisture provides a medium for SRB growth and chemical reactions to occur. Infiltration of
stormwater into the waste, lack of leachate collection and removal, and moisture inherent to
deposed waste can all act to contribute to moisture within landfills.
Production of hhS requires organic matter as a substrate for SRB utilization. Several
studies (Hardy Associates, 1978; Townsend etal., 2002, New Hampshire Department of
Environmental Services 2004) have indicated organic matter presence in C&D landfills is
not limiting, and that the paper backing on drywall is sufficient to sustain a viable community
of SRB that can produce H2S. MSW landfills have substantially more organic matter
compared to C&D landfills because of the characteristics of wastes that are normally
deposited in MSW landfills.
Anaerobic conditions (i.e., a lack of oxygen) are required for the reduction of SO42~into H2S.
Anaerobic conditions form within C&D and MSW landfills following placement and
subsequent compaction of waste material.
SRB typically thrive in environments with pH ranging from 6 to 9, though SRB have been
observed in environments with greater acidity (Koschorreck, 2008). These pH conditions
are consistent with those normally found in C&D and MSW landfills.
SRB can thrive over a wide range of temperatures - investigators have observed SRB in
the thermophilic range at temperatures up to 80 °C (Elsgaard et al., 1994) and at cryophilic
ranges as low as -1 .8 °C (Knoblauch and Jorgensen, 1 999).
SRB produce H2S gas from the SCV present in gypsum and organic carbon waste materials, as
demonstrated by using formaldehyde (ClrbO) as an example (Townsend et al., 2002; Bogner and Heguy,
2004):
S0%- + 2CH20 -> 2HCOJ + H2S
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Based on stoichiometry, one hundred tons of SC>42 have the potential to produce 35 tons of FfcS gas
(Bogner and Heguy, 2004).
Laboratory studies have examined FfcS production potential in batch reactors or in simulated landfill
columns. Yang et al. (2006) measured H2S concentrations as high as 65,000 (iL/L in a reactor containing
only drywall that was flushed with a synthetic precipitation leaching procedure solution, which is a
simulated rainfall used in standard laboratory leaching tests. Additionally, Yang et al. (2006) tested a
simulated column with mixed C&D debris (wood and drywall) and flushed in a similar fashion as the
drywall-only experiment, and the results showed an FfcS concentration of approximately 40,000 (iL/L.
2.4 Factors Impacting Emission of LFG
The emission of landfill gas (LFG) from landfills depends on the different transport mechanisms
associated with the LFG and the factors that influence the transport mechanisms. The mechanisms and
influencing factors are presented in Table 2-4.
Table 2-4. Transport Mechanisms and the Factors That Impact LFG Emission (U.S. EPA 1997)
LFG Transport
Mechanism
Diffusion Through the
Waste or Cover Soils
Diffusion Through the Air
Boundary Layer
Convection
Displacement
Factors that Impact Emission
• Soil porosity
• Concentration gradient
• Diffusivity of the LFG
• Thickness of cover soil
• Wind speed, which is related to atmospheric stability
• Concentration gradient
• Diffusivity of the LFG
• Pressure gradient (which is influenced by LFG production rates). A
larger pressure gradient between the landfill and the atmosphere
results in greater emissions.
• Compaction or size reduction of waste
• Settlement of waste
• Water table fluctuations (unlined sites)
• Changes in atmospheric pressure
H2S migrates with LFG through pore space and soil cover in landfills to escape to the atmosphere. H2S is
heavier than air and thus tends to settle in low-lying areas, including outside of the landfill boundary.
Pressure changes (causing convection) in the landfill are influenced by nutrient availability, refuse
composition, moisture content, landfill age, temperature, pH, oxygen availability, the presence of a LFG
collection system, and wastes that may inhibit biological activity (industrial waste, or waste containing
large quantities of metals). Landfill settling and compaction can also cause displacement of LFG and
force the gas to migrate out of the landfill. The displacement can occur also through water table
fluctuations, which are affected by the presence of a liner, evaporation, precipitation, and variations
between horizontal and vertical permeability. If the landfill is unlined, the ground water table and
surrounding water bodies may have an impact. Xu et al. (2014) developed a model to predict emitted
concentrations of H2S based on conditions that may be present at a specific site (e.g., cover soil thickness,
cover soil compaction, and moisture content of the cover soil).
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H2S has a relatively high solubility, thus the gas tends to dissolve in landfill leachate and serve as an
emissions source in leachate collection areas or areas on a landfill where leachate is exposed to the
atmosphere (Profumo et al., 1992; Reinhart et al., 2004).
Evaluation of where H2S concentrations are measured at landfills is an important consideration, as the
implications measured inside of the landfill differ from those measured at the property boundary.
Figure 2-2 presents an illustration of a landfill and the locations where LFG samples including H2S may
be collected. Additional discussion regarding these potential sampling locations is presented below.
• LFG Header Pipe, LFG Well, or Soil Vapor Probe. Concentrations measured at these
locations would be expected to be the highest measured H2S levels at a landfill, as limited
dilution with atmospheric air would have occurred. Normally, measurements are conducted
by directly connecting the monitoring instrument to the pipe or probe. Monitoring H2S at
these points may help to identify areas of high concentrations in the landfill or allow the
operator to evaluate overall collected H2S concentration, which has importance particularly at
sites with energy conversion systems.
• Landfill Surface. Measurements conducted at the landfill surface can identify areas of high
concentration and assess concentrations to which landfill workers or site visitors may be
exposed. Measurements at the surface are typically conducted anywhere from just above the
surface to the normal breathing zone, depending on the goals of monitoring and the
instrument used.
• Ambient Air. Measurements in ambient air are typically conducted to measure the
concentration of H2S that may be present at the landfill's perimeter, property boundary, or
even offsite. Measurements can be conducted with fixed instruments (which analyze H2S
levels at a single point) or using a roving instrument to capture a larger area.
Landfill Gas
Concentration
LFG Well Soil Vapor Landfill Surface
Probe Concentrations
) ) )
\ < \
Flare/Energy
System
Lajm
drill
Ambient Air
Concentration
Leachate collection system (if present)
j Landfill
Perimeter
Leachate Collection
System Sump
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Figure 2-2. Illustration Indicating Common Landfill Processes and Examples of Areas Where hhS
May Be Sampled
Sections 2.6 and 2.7 discuss H2S production and measured concentrations at C&D landfills and MSW
landfills, respectively. Information in each section is grouped to acknowledge measurements of H2S
inside of landfills, on the surface of landfills, and in ambient air on or off of the landfill property. The
concentrations measured at each of these points have different implications with respect to operational
impacts, environmental impacts, and human health impacts.
It is noted that the monitoring or measurement of H2S is not necessarily a standard practice at C&D or
MSW landfills, and that some data in Section 2.6 and 2.7 were gathered based on published information
at sites where an actual or suspected problem with H2S production or emissions was present. Therefore,
the concentrations presented in this report should not necessarily be viewed as "typical" or "average" for
C&D landfills or MSW landfills, but simply examples of concentrations that may be encountered. As
discussed previously, numerous site-specific factors (waste types and quantities, weather conditions,
topographic conditions, distance to receptors) play a role when considering whether a landfill has H2S
production or emissions at problematic levels.
2.5 Composition of Waste Disposed of in C&D and MSW Landfills
Assessing the composition of waste disposed of in C&D debris and MSW landfills is important to
understand the potential for the formation of H2S in these facilities. Gypsum drywall is one of the major
components of the C&D debris waste stream. Staley and Barlaz (2009) summarized several statewide
studies that estimated the composition of C&D debris discarded at landfills. The mean weight-based
composition was calculated and is presented in Figure 2-3. Based on composition data reported by seven
states in the United States, the average weight-based composition of discarded gypsum in C&D debris
was calculated to be approximately 10%.
U.S. EPA (1998a) and (2009) presented estimates of building-related C&D debris generation in the
United States based on an assumed waste weight per unit construction activity area and Census Bureau
data on construction industry project activity. These studies estimated a building-related C&D debris
generation rate estimate of 136 and 170 million tons for years 1996 and 2003, respectively. The
estimated recycling rate of C&D reported by U.S. EPA (1998a) ranged from 20 to 30%; the most
commonly recycled components included concrete, asphalt, metal, and wood. Assuming that the drywall
recycling rate based on the 1996 data was minimal, the amount of disposed gypsum drywall may be on
the order of 10 million tons annually in the United States.
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Other C&D
14%
Gypsum Drywall
10% M Lumber
40%
Concrete/Rock
/Brick
11%
Soil/Fines
11% Asphalt Products
14%
Figure 2-3. Mass-Based Discarded C&D Debris Composition Based on Reported Data From Seven
States (adapted from Staley and Barlaz, 2009)
The generation of MSW in the United States is estimated annually by the U.S. EPA. In 2010, total MSW
generation was estimated to be 250 million tons, with an approximately 34% recycling rate and 54%
discard rate (U.S. EPA, 2011). Staley and Barlaz (2009) summarized reported statewide waste
composition data for discarded MSW, as shown in Figure 2-4. It is important to note that many MSW
landfills accept waste other than MSW (e.g., C&D debris, industrial wastes, and ash). C&D debris may
be disposed of at an MSW landfill for a variety of reasons, including (but not limited to) lack of recycling
markets, lack of permitted C&D debris-only facilities, and disposal costs.
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Durable Goods
7%
Plastics
Organ ics
29%
Figure 2-4. Discarded MSW Composition by Mass (adapted from Staley and Barlaz, 2009)
Accurate nationwide estimates of the fraction of waste received at MSW landfills that is composed of
C&D debris are not available. However, statewide characterization studies can provide relevant data. For
example, a statewide waste characterization study conducted in Delaware that examined the waste
composition of six facilities owned by the Delaware Solid Waste Authority found that approximately
23% (weight basis) of materials handled at these facilities was C&D debris (Delaware Solid Waste
Authority, 2007). So while accurate nationwide estimates of the fraction of waste disposed of in MSW
landfills that consists of C&D debris are not available, the data from Delaware show that the amount of
C&D debris disposed of in MSW landfills can be substantial.
2.6 H2S at C&D Debris Landfills
2.6.1 Factors Contributing to h^S Formation and Emission at C&D Landfills
The data presented in Section 2.5 show that potentially large quantities of SCV from gypsum drywall
disposal are available at C&D landfills. Coupling this with the fact that these landfills harbor the broad
conditions that need to exist at landfills for IrkS formation to occur, the potential exists for appreciable
quantities of IrkS to form at C&D landfills. Additional conditions that may promote IrkS production at
C&D landfills are summarized in Table 2-5.
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Table 2-5. Conditions That May Promote hhS Production at C&D Landfills
Condition or
Factor
Cover Soil
Requirements
Discussion
Cover soil requirements at C&D landfills (which can reduce the amount of stormwater
that infiltrates into the waste and can also serve to reduce quantities of hhS emitted
as described later) are limited in some states. A review of state-mandated cover soil
requirements indicated that 12 states require daily cover, 14 require weekly cover at a
minimum, and 24 states have no operational cover requirements or a cover
placement requirement less frequent than weekly (U.S. EPA, 2012b). The lack of a
cover soil requirement may tend to increase the production of hhS by promoting
conditions that cause its formation.
Bulky Nature of C&D
Debris
The bulky nature of C&D debris may allow moisture to more readily infiltrate into the
waste or percolate through the waste when compared to another waste stream such
as MSW.
Liquids
management
As of 2012, 17 states in the US have a minimum requirement for C&D landfills to
collect and remove leachate (U.S. EPA, 2012b). Depending on local geology (e.g.,
presence of a low permeability layer underlying the waste or presence of groundwater
at or near the waste bottom), conditions may form that allow for the build-up of
moisture or the contact of groundwater with the waste mass. This could increase
moisture content of waste and result in greater hhS formation, but could also result in
greater leaching of SCU2" into solution, thus representing a potential source for hhS
off-gassing within or beyond the landfill footprint. Also, recirculation of leachate into
the waste and poor surface water management can lead to an increase in waste
moisture content.
Placement of Size-
Reduced Gypsum
Drywall in the
Landfill
Some C&D landfills accept or have accepted size-reduced C&D debris, which can
include ground-up pieces of gypsum drywall. The reduced size creates an increased
specific surface area which can lead to greater rates of hhS gas production compared
to larger, bulkier pieces of drywall. Size-reduced gypsum drywall may be in the form
of processed C&D debris or in RSM.
2.6.2 H2S Concentrations Measured at C&D Landfills
This section summarizes measured H2S concentrations at C&D landfills, focusing on the three major data
types presented in Figure 2-2. This includes data collected in the waste or LFG extracted from the waste,
at the landfill surface, and in ambient air at or near C&D landfills. The data indicate levels of H2S that
may be encountered at a C&D landfill based on what has been reported in the technical literature and
other sources.
H2S Measurements in LFG at C&D Landfills
Although most C&D landfills do not have active LFG collection, data from a limited number of sources
were examined to assess concentrations of H2S that have been measured at C&D landfills. Lee et al.
(2006) sampled in-situ LFG using soil vapor probes installed 0.3 m below the landfill surface and from
existing passive gas collection vent wells at 10 C&D landfills. The results showed highly variable H2S
concentrations, ranging from <0.03 (iL/L to 12,000 \\LfL. Collected samples from the C&D landfill with
the highest observed H2S concentrations, which showed a mean concentration of 2,110 (iL/L and a
median of 1,800 (iL/L, were collected from passive gas collection vent wells.
Sampling from two leachate cleanout lines at a C&D landfill in Ohio showed H2S concentrations as high
as 1,995 uL/L and 600 uL/L (Rizzo and Associates, 2002). A 74-acre C&D landfill in Kansas
experienced H2S odor problems attributed to the collection and buildup of stormwater within the waste
footprint because of a low-permeability shale layer underlying the site and lack of a mechanism to remove
the liquid. The landfill contains 25 onsite wells that serve as the LFG collection system. Degner (2008)
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reported an average collected LFG H2S concentration of 54 (iL/L, with a range of 4 to 120 (iL/L at a
facility in Kansas.
H2S concentrations were measured at a New York landfill with two phases devoted to C&D disposal.
Phase 1 consisted of processed C&D debris and Phase 2 consisted of bulk C&D debris (McCarron and
DiMaria, 2007). H2S measurements conducted in 2000 in Phase 1 reached 9,000 (iL/L. Investigations
conducted between 2001 and 2006 in Phase 1 measured concentrations as high as 12,000 (iL/L and Phase
2 concentrations as high as 18,000 (iL/L.
Figure 2-5 summarizes the measured concentrations of H2S within C&D landfills reported in the
investigations described above.
10*
o
'-I—'
ro
o>
o
o
O
(f)
10* -
10° -
10-1-
10-
• Mean Observed Concentration
n Maximum Observed Concentration
o
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12
C&D Landfill Site
Sam ping Methodology
*1,2,5: Soil Vapor P-obeand Soil Vapor We s
ff3,7,8, 9,10: Soil Va por Probe On ly
W4: Passive Vent Weis
*6: AvEr3£Eof 3 Lsact-EteC earoLt Grab Sarrp ei
ttil: LF5 Exfact'or
Figure 2-5. Reported hhS Concentrations Measured Within Landfilled C&D Waste or in an LFG
Well at a C&D Landfill (#1 - 10: Lee et al. (2006), #11: Rizzo and Associates (2002), #12: Degner
(2008))
H2S Concentration Measurements at the Landfill Surface of C&D Landfills
Lee et al. (2006) measured H2S concentrations on the surface of 10 C&D landfill sites in Florida to
measure concentrations near soil vapor probes. The results indicated readings between <0.003 (iL/L and
>50 (iL/L; detections of H2S at the landfill surface occurred in 48% of measurements. The two sites with
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the highest observed H2S concentrations (maximum concentrations of >50 (iL/L at the surface) were sites
known to accept processed C&D debris.
The ATSDR (2007) reported on H2S concentrations measured using personal badge monitors affixed to
landfill workers during the work day at a C&D site. The maximum observed concentration from this
evaluation was 130 (iL/L. Figure 2-6 summarizes the reported H2S surface concentration measurements
from these studies. The figure shows that three of the landfills had a maximum H2S concentration greater
than 10 (iL/L, which exceeds the AEGL-1 standard presented in Appendix A, and other guideline levels.
o
01
o
c:
o
O
CO
if
10'
10° -
10-' -
10- -
Observed Concentration
n Maximum Observed Concentration
o a
D
n n
n •
O
#1 #2
#3
#4 #5 #6 #7 #8
C&D Landfill Site
Representative of peak Landfill worker badges concentration
#9 #10 #11
Figure 2-6. Reported hhS Concentrations Measured at the Surface of 11 C&D Landfill Sites in
Florida (#1 - 10: Lee et al. (2006), #11: ATSDR (2007))
Eun et al. (2007) measured the H2S flux from five C&D landfills (n = 20 measurements per site) in central
Florida during the summer using a dynamic flux chamber. Measured flux rates ranged from 0. 192 - 1 .76
mg/m2-day. These flux rates are less than those reported for LFG flux rates reported by Amini and
Reinhart (2012) at MSW landfills, which was approximately 20 to 120 g/m2-day. The H2S measured by
Eun et al. (2007) was detected at frequencies ranging from 10% to 55% of measurements, indicating that
emissions through the cover of C&D landfills were variable.
Ambient H2S Concentrations Measured Near C&D Landfills
Residents living near a C&D landfill in Florida with documented odor nuisance problems wore H2S
personal badge monitors for one month. The results showed 15 positive detections of H2S, ranging from
0.015 to 0.123 (iL/L. Additionally, stationary ambient air monitors detected H2S concentrations up to
0.224 (iL/L (ATSDR, 2007).
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Cooper et al. (2011) utilized techniques to assess H2S emission rates from C&D landfills to calculate an
odor buffer distance beyond which nuisance odors would not be detected. The study measured H2S
concentrations near a C&D landfill in Florida and subsequently used the measured results in a model that
used aproblematic odor threshold (0.015 (iL/L, which was established based on a literature review of six
studies) to delineate the odor buffer distance from the landfill. H2S readings were measured in the
morning, where higher concentrations were more likely because of lower atmospheric turbulence. On the
first site visit, H2S concentrations from 0.2 (iL/L to 0.4 (iL/L were observed at two corners of the landfill,
at a maximum of approximately 40 m from the edge of the landfill. H2S concentration declined to 0.015
(iL/L at approximately 70 to 200 m from the landfill edge. On the second site visit, H2S measurements
surrounding the landfill was >0.8 (iL/L.
Table 2-6 shows the modeled buffer distances with their corresponding predicted H2S concentration
ranges. The calculated buffer distance varied substantially between the two visits (which was a reflection
of the difference in measured concentrations at the landfill). This demonstrates a couple of important
phenomena: 1) that the concentration of H2S produced from landfills has the potential to be highly
variable, even when measured at a similar time of day at the same location; and 2) based on the results of
site-specific atmospheric modeling, the impact that the source H2S concentration has on the area
surrounding the landfill that may experience problematic H2S concentrations is dramatic.
Table 2-6. Calculated Modeled Minimum Nuisance Odor Buffer Distances Based on
Measurements Collected at a Florida C&D Landfill (adapted from Cooper et al., 2011)
Measured hhS Concentration
Near Landfill (uL/L)
0.0-0.015
0.015-0.030
0.03-0.10
>0.10
Site Visit #1 :
Buffer Distance
(m)
600
400
200
100
Site Visit #2:
Buffer Distance
(m)
2,800
2,400
2,000
1,600
A C&D landfill site with reported odor issues in Ohio reported monitoring data from three ambient
monitoring locations (bordering the landfill perimeter) of 60-minute rolling average H2S concentrations of
0.154 uL/L, 0.043 uL/L, and 0.071 uL/L during September 2004 (Tetra Tech, 2004).
Figure 2-7 displays ambient air H2S data collected from three different sites as reported by ATSDR
(2007), Tetra Tech (2004), and Cooper et al. (2011).
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10'
c
o
"c
a;
o
!Z
O
O
CO
r*J
10-' -
1C-2
• Minimum Observed Concentration
n 1-hour Average Concentration
n Maximum Observed Concentration
#1'
#2
C&D Site
#1 : Residential Badge Monitors
#1E: Ambient Air Perimeter Monitors
#2: Ambient Air Perimeter M onitors
tt3A: 1st monitoring event
#3 : 2nd monitoring event
Figure 2-7. Compilation of Ambient Air H2S Measurements Near C&D Landfills (#1: ATSDR (2007),
#2: Tetra Tech (2004), and #3: Cooper et al. (2011))
Summary
The results show that measured concentrations within C&D landfills, and in some cases at the landfill
surface, are high enough to fall within the range where acute exposure symptoms may occur. Data from
the measurements in the waste mass or collected LFG showed H2S concentrations above the level that
could cause death in a short-term exposure scenario. Thus, operators at C&D debris landfills that accept
gypsum drywall should be made aware of the potentially high concentrations of H2S that may be
encountered.
The measured landfill surface H2S concentrations in the studies evaluated were somewhat variable, but
several cases indicated concentrations that may be of concern. For example, one site reported an H2S
concentration measured by a personal badge worn by a landfill worker during the work day of greater
than 100 u,L/L, which exceeds the Occupational Safety and Health Administration's Immediately
Dangerous to Life and Health level of 100 u,L/L (refer to Appendix A for details on additional H2S
guidance and standards). In the 10-landfill study conducted by Lee et al. (2006), the mean surface H2S
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concentration was less than 10 (iL/L for each site, but two sites had measured concentrations greater than
the 10-minute AEGL-1 (which corresponds to nuisance and irritation in a short-term exposure scenario)
and five of the sites examined by Lee et al. (2006) had a measured concentration that exceeded the
ATSDR's acute maximum risk level.
The H2S concentrations reported in ambient air near three C&D landfills (two of which were sites that
had reported H2S emission problems) indicate that the potential exists for the detection of H2S
concentrations above nuisance odor thresholds at or beyond the landfill property boundary, but the results
varied and demonstrated that the presence of problematic or nuisance-level H2S concentrations is not
necessarily constant. The effect that H2S source concentration at the landfill on the migration of H2S off-
site can be dramatic, as demonstrated by Cooper et al. (2011), which underscores the importance of
mitigating H2S at the landfill site.
1G5
03
-b
(D
o
!=
O
O
CO
101 -
102 -
10" -
10---
10-1-
10
-4
a
B
• Minimum Observed Concentration
a Average Observed Concentration
D Maximum Observed Concentration
#1 #2 #3 #4 #5 #6 #7
MSW Landfill Site(s}
#1 : Compilation of data from multiple sites for A P-42 defaults
2. 7 H2S at MS W Landfills
2.7.1 Factors Contributing to
Formation and Emission at MSW Landfills
The conditions that cause H2S formation in MSW landfills are similar to C&D landfills, in that a SC>42~
source, carbon source, anaerobic conditions, moisture, and appropriate pH and temperature must be
present. Gypsum drywall may be disposed of in MSW landfills through bulk C&D disposal, processed
C&D disposal, or the use of C&D fines (also referred to as RSM) for initial cover or for grading and
shaping of side slopes.
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The presence of gypsum drywall in MSW landfills is a large contributor to FfcS formation at these sites.
Fairweather and Barlaz (1998) conducted laboratory experiments comparing SCV reduction in reactors
containing fresh MSW with and without gypsum drywall. The results indicated that the reduction of
SC>42 to FfcS occurred concurrently with the production of methane (CFL) from the MSW, and the
reactors containing gypsum drywall produced sulfur emissions that were 10 times greater compared to the
reactors without added gypsum drywall.
In contrast to C&D landfills, MSW landfills are required per federal regulations (40 CFR Part 258) to
apply a soil cover (or equivalent) at least daily to control moisture and reduce odors and disease vectors.
Thus, the presence of a daily cover is expected to reduce the infiltration of stormwater relative to a C&D
landfill that does not have a soil cover requirement; however, it is expected that the higher moisture
content inherent in MSW supplies enough moisture to contribute to FfcS production.
Several factors exist at MSW landfills that may contribute to the production or emission of FfcS beyond
the basic conditions that must be met for H2S to form. These factors are presented in Table 2-7.
Table 2-7. Conditions That May Promote H2S Production at MSW Landfills
Condition or
Factor
SC-42' Source
Waste
Moisture
Content
LFG
Production
Rate
RSM Use in
Cover Soil
Leachate
Recirculation
Discussion
Larger sources of SCM2' from gypsum drywall may be present, in addition to other potential
sources such as sludges. The amount of the SCM2" is a function of the amount of SCM2"-
containing wastes accepted by the facility, which can vary widely. For example, a statewide
characterization of waste at disposal facilities in Georgia indicated a weighted average of
approximately 12% C&D debris (out of the total waste disposed in MSW landfills in the state),
with a range of 0 % to 50% (Georgia Department of Community Affairs, 2005).
The nature of MSW differs from C&D debris in several ways, including the inherent moisture
content of the waste as delivered to the disposal facility. Reported weight-based moisture
contents range from 15% to 40% (Tchobanoglous et al., 1993), although multiple investigators
have shown amounts beyond this range (e.g., 46% [EI-Fadel, 1999]).
The content of highly and moderately degradable organic waste normally found in MSW
landfills results in the production of large volumes of LFG (particularly relative to C&D
landfills), which may lead to greater transport of hhS into LFG collection systems or through
the landfill surface.
MSW landfills have more stringent cover application requirements compared to C&D landfills,
and as a result several MSW landfills have evaluated sources of material to use as cover,
including RSM. Several states (e.g., Massachusetts) have C&D recycling mandates, thus the
expansion in availability of RSM has led to an increase in the delivery of this material to
facilities that beneficially use (as an alternative daily cover [ADC]) or dispose of the RSM.
Several states have granted approvals for using RSM as an ADC. The presence of fine
gypsum particles in RSM, which can be dramatic (Musson et al. (2008) measured the gypsum
content of RSM from several facilities in the U.S. and the results ranged from 1% to 25% by
weight gypsum) can lead to the production of hhS.
Leachate recirculation is a common practice at MSW landfills. This process attempts to raise
the moisture content of MSW in order to promote decomposition of the waste. Subsequently,
gas production is increased, thus increasing the production of hhS.
2.7.2 H2S Concentrations at MSW Landfills
H2S Measured in MSW LFG
H2S in MSW LFG can pose additional issues beyond potential worker health and safety and nuisance
conditions—specifically, sites that have active gas collection and control systems (GCCS) may be at risk
of triggering emission thresholds for sulfur oxides (SOX) if mass flow rates of FfcS are high enough (FfcS
is converted into SOX following combustion in typical LFG destruction devices). SCh is one of the six
priority pollutants that are subject to the National Ambient Air Quality Standards (U.S. EPA, 2012a).
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Landfills with Title V air permits and/or stationary source permits typically have an upper allowable limit
of 862 emissions. Additionally, high H2S concentrations can be problematic at MSW landfills that collect
and beneficially use LFG to produce energy because a performance standard related to H2S
concentrations must usually be met (these performance standards vary depending on the type of energy
conversion system, as discussed in Section 3.2.5); the requirement to reduce H2S concentrations to meet
these levels represents a cost that can impact energy project economics.
U.S. EPA (1998b) reported a default H2S concentration of 35.5 uL/L for MSW LFG in the compilation of
air pollutant emission factors (AP-42), which was developed based on the average of 37 test reports
analyzed. The AP-42 develops emission factors, which facilitate the estimation of emissions from various
sources of air pollution. The emission factors are typically averages of available data of acceptable
quality. In recent years, U.S. EPA (2008) began to update the AP-42 default concentrations based on
more recent measurements, and a draft background document presented updated H2S monitoring data
collected from active GCCS. Table 2-8 presents summary statistics of the H2S concentrations reported in
U.S. EPA (2008). Note that the majority of data points were collected from MSW landfills in California.
Table 2-8. Summary of hhS Concentration Data in MSW LFG Reported in the Draft Compilation of
Air Pollutant Emission Factors for MSW Landfills (U.S. EPA, 2008)
Metric
Minimum Concentration
Maximum Concentration
Mean Concentration
Standard Deviation
95% Upper Confidence
Level
Value (uL/L)
0.001
330
32.0
55.7
18.2
H2S was measured in the field from active GCCS wells at an MSW landfill in Virginia that had been the
subject of odor complaints. The results showed that approximately 15% of wells (approximately 22 out
of 129) exhibited an H2S concentration greater than 2,000 (iL/L (Tennant, 2012). Note that these
concentrations were measured prior to a destruction device. The U.S. EPA (2007) conducted a study of
five MSW landfills (two in the Northeast and three in the Midwest) with active GCCS. LFG samples
were collected from the GCCS from a main header pipe (which represents the cumulative volume of LFG
collected from each site). The results of the sampling events are presented in Table 2-9.
Table 2-9. Reported H2S Measurement Data From Five MSW Landfills (U.S. EPA, 2007)
Landfill
A
B
C
D
E
Range of H2S
Measured in Raw
LFG (uL/L)
7.6-18.4
18.7-25.6
19.0-78.0
22.7-132
291 - 366A
Average HhS
Concentration in
Raw LFG (uL/L)
13.0
22.9
55.5
72.7
322A
A: Estimated Value
Capenter and Bidwell (1996) reported an H2S concentration (determined by a chemiluminescence
detector) in MSW LFG of 28.33 (iL/L from a 60-acre landfill in Connecticut from a GCCS header pipe.
A regional MSW landfill in New Jersey accepted C&D screenings from 1998 to 2004 for use as an ADC
(Carlton et al., 2005). The site began to receive odor complaints in 2002 (and reportedly had not received
any odor complaints prior to this time) and an active GCCS was installed in early 2003 and expanded in
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early 2004. LFG sampling in 2004 revealed H2S concentrations up to 11,600 (iL/L. Prior to acceptance
of C&D screenings, a target SCV level in the screenings was established at 3% (by weight). Monthly
testing reportedly indicated the target SO42" level was met (Carlton et al., 2005). Figure 2-8 presents a
summary of reported H2S measurements in MSW LFG presented by U.S. EPA (1998b), Tennant (2012),
U.S. EPA (2007), Capenter and Bidwell (1996), and Carlton et al. (2005).
1
— 1
c
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o
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a
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• Minimum Observed Concentration
n Average Observed Concentration
o Maximum Observed Concentration
TT \ T"l~i rfj M'' I T^ D T^ U T*~ / T^O T^J
MSW Landfill Site(s)
#1 : Compilation of data from multiple sites for A P-42 defaults
Figure 2-8. H2S Concentrations Measured in LFG at MSW Landfills (#1: U.S. EPA (1998b), #2:
Tennant (2012), #3-7: U.S. EPA (2007), #8: Capenter and Bidwell (1996), and #9: Carlton etal.
(2005))
Anderson et al. (2010) conducted a study to estimate the H2S production potential and kinetics based on
the acceptance of C&D screenings at MSW landfills using SO42" content measurement data from the C&D
screenings and field-measured H2S concentrations. The range of field-measured H2S concentrations was
from approximately 100 U.L/L to 14,000 U.L/L. Models were developed to predict H2S production
amounts based on data collected from six different landfills. The average production potential was
calculated to be 4,310 ft3 of H2S per ton of sulfur in C&D fines. Anderson et al. (2010) also suggested
that H2S from the production of C&D screenings in MSW is expected to peak and decline more rapidly
compared to CH4 production.
The data provided in this section indicate that the concentrations of H2S that can be formed in MSW
landfills can be significant and comparable to levels measured in C&D landfills.
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H2S Concentrations Measured on the Surface of MSW Landfills
Gowing (2001) measured the flux of several gases, including H2S through the landfill surface using a flux
chamber at an MSW landfill in Waterloo, Canada. A total of 20 sampling locations that consisted of a
30-cm thick interim cover comprised of clay. The landfill site had an active GCCS in place on the side
slopes, and measurements were taken in areas that were and were not under the influence of the GCCS.
The results ranged from below the detection limit to approximately 7.7 (iL/L. Measurements in the areas
of highest H2S flux ranged from approximately 4.2 (iL/L to 7.7 (iL/L.
Capenter and Bidwell (1996) measured ambient air samples 10 to 13 cm above the landfill surface,
collected in a grid pattern, at a regional MSW landfill in Connecticut that had been subject to offsite odor
complaints. At the time of the study, an active GCCS and enclosed flare had been operational for 2 years
and intermediate or daily cover soil was in place at the site. Five grids on the landfill surface
encompassing 4,650 m2 were sampled over 9 days in locations considered to be "worst-case scenario"
(e.g., odors noted previously, visible leachate or residue). H2S in ambient surface air was measured to be
0.00095 (iL/L. As a point of reference, the measured concentration of H2S during the study collected
from an active GCCS header was approximately 27 (iL/L.
Ambient H2S Concentrations Measured Near MSW Landfills
An ATSDR (2009) public health assessment of an MSW landfill in New York found offsite migration of
H2S resulting from poor operational practices exceeding 1 (iL/L (daily maximum levels exceeding 3
(iL/L) at the landfill perimeter for a period of 2 months (December 1990 and January 1991) before control
measures were put in place and concentrations decreased to approximately 0.5 (iL/L in downwind
samples.
An MSW landfill that also included a C&D landfill in Ohio accepted a large amount of size-reduced
C&D debris that resulted in odor problems (Ohio Environmental Protection Agency [OEPA], 2006).
Roving monitoring data near the perimeter of the facility in 2005 exhibited 1-hour average H2S
concentrations ranging from 0.031 (iL/L to 0.078 (iL/L. During the same time frame, a 24-hour average
of 0.011 (iL/L was measured.
As part of an effort to address H2S odors emanating from an MSW landfill in Illinois, which was
attributed to the acceptance of pulverized C&D debris, a year-long monitoring effort was conducted to
establish ambient H2S concentrations around the site perimeter and define fluctuations in concentration
that could be related back to weather data and landfill operations by the Lake County Health Department
and Community Health Center (LCHDCHC; 201 la, 201 Ib). Three high-sensitivity, Honeywell low-level
H2S single-point monitors were installed around the perimeter of the site (one at a location upwind [#1]
and two located downwind [#2 and #3]) from April 2010 through March 2011; the monitors had a lower
detection limit of 1 nL/L (0.001 (iL/L) and an upper detection limit of 90 nL/L (0.09 (iL/L).
The monitoring results showed that a measured H2S concentration greater than 0.005 (iL/L was observed
at monitor #2 at least once on 82 different days, whereas monitor # 1 and #3 had a measured concentration
exceeding 0.005 (iL/L on 28 and 21 different days, respectively. Measured H2S concentrations of greater
than 0.09 (iL/L were observed once at monitor #1 and #3 and on seven different days at monitor #2. The
location of monitor #2 was most proximate to an area of the landfill where pulverized C&D was disposed.
In general, peaks in H2S concentration occurred during the late evening and early morning hours, when
wind activity was minimal.
Heaney et al. (2011) evaluated H2S concentrations measured between an MSW landfill and a neighboring
community that was located within 0.75 miles of the site. Measurements using two different fixed H2S
monitors were conducted. One monitor conducted measurements at 15-minute intervals for 47 days, and
one analyzer conducted measurements at 5-minute intervals for 58 days. The H2S 1-hour average
concentration during the study period was 0.00022 (iL/L, with a range of below detection limit to 0.0023
(iL/L. The H2S monitoring results were compared with reports from nearby residents that maintained a
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log of observed odor. The results were mixed to some degree in that resident observations of odor did not
always correlate with an observed detection of H2S. For example, 76% of reported "no odor"
observations corresponded with FbS detections less than 1 nL/L, and 72% of reported "no odor"
observations corresponded with FbS detections greater than 1 nL/L. Conversely, 8% of "strong" odor
observations by residents corresponded to instances of H2S less than 1 nL/L, but 6% of "strong" odor
observations corresponded to instances of FbS greater than 1 nL/L. The results of the study underscore
some of the challenges associated with correlating a subjective observation (i.e., the presence of odor)
with quantitative measurement data. Figure 2-9 presents a summary of ambient concentrations reported
by OEPA (2006), ATSDR (2009), and Heaney et al. (2011).
10
E
Q.
Q.
C
o
I
"c
CD
O
c
o
O
(N
1 -
0.1 -
0.01 -
0.001 -
0.0001
n
D
• Minimum Observed Concentration
D Average Observed Concentration
D Maximum Observed Concentration
D
D
#1
#1
#2
#3
at MSW
MSW Landfill Site(s)
#1 : Min and Max 1-hour Average Concentrations (exceed std.)
n
#1 : 24 hour Average (exceed std.)
#2: Prior to control measures
#3: 1-hour average
Figure 2-9. Ambient, Perimeter, and Offsite Measured or Modeled Concentrations of
Landfills (#1: OEPA, 2006' #2: ATSDR, 2009; and #3: Heaney et al., 2011)
Summary ofH2S Measured at MSW Landfills
The FbS measurement data from LFG at MSW landfills suggest that high concentrations of FbS may be
produced at levels comparable to that measured within C&D landfills. In many of the cases presented,
the measurements were taken from a GCCS (either individual collection wells or header pipes). The
results indicate the importance of routine monitoring of FbS for systems that have active GCCS,
particularly larger sites that may accept gypsum drywall or RSM, as potentially high H2S concentrations
may impact LFG to energy systems and in some cases could have implications on SOX limits in a
landfill's Title V permit.
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The results of landfill surface concentration sampling of H2S were somewhat variable, with one case
indicating low measured concentrations that were generally less than the nuisance level for H2S presented
by Amoore (1985) and comparable to U.S. EPA (2010a) reported atmospheric concentrations of H2S.
Another case indicated measured concentrations greater than 1 (iL/L, exceeding irritation levels
summarized by WHO (2003), and some of the exposure guideline levels presented in Appendix A. The
results indicate different factors such as operation of a GCCS, cover soil type and quality, and H2S source
concentration can have an impact on measured concentrations at the landfill surface.
Ambient H2S concentration data, similar to surface concentration measurements, were variable. Data
from the sites in Ohio and Illinois both indicated ambient concentrations beyond the landfill footprint
greater than the H2S nuisance level of 0.015 (iL/L reported by Cooper et al. (2011), and in the case of
Ohio, measured concentrations exceeded the acute minimum risk level of 0.07 \\LfL established by
ATSDR. Conversely, monitoring data near a landfill in North Carolina indicated H2S concentrations
below nuisance levels and most of the reported human odor detection limits as well. Regardless of the
low H2S levels, the evaluation by Heaney et al. (2011) concluded that observations and log books
maintained by nearby residents during the study still indicated effects such as irritation and behavioral
changes.
2.8 Considerations for Other Reduced Sulfur Compounds
Although H2S is the most-studied RSC with respect to landfill emissions, other RSCs have been
investigated in LFG; most are malodorous, with low odor thresholds, and considered undesirable
contaminants in LFG (Moreau-Le Golvan, 2003). Other RSCs that may be detected in LFG include
methyl mercaptan (CH3SH), isopropyl mercaptan (C3H8S), isobutyl mercaptan (C4Hi0S), dimethyl sulfur
((CH3)2S), dimethyl disulfide ((CH3)2S2), dimethyl trisulfide ((CH3)2S3), carbonyl sulfide (COS), carbon
disulfide (CS2), and tert-butyl mercaptan (CFLHioS). These compounds generally are malodorous, and
some have odor thresholds at similar concentrations to H2S. Christensen et al. (1996) reports that RSCs
such as mercaptans are formed from highly degradable materials and are usually only found during the
initial operational phase of the landfill, whereas H2S is normally generated in all phases of a landfill's life.
As with H2S, the odor detection threshold of other RSCs occurs at different concentrations based on the
individual. ATSDR (n.d.) reports odor thresholds for CH3SH of 0.002 (iL/L, Cameo Chemicals (1999)
reports 0.00025 (iL/L as an odor threshold for C3H8S, and ATSDR (2011) reports CS2 can be detected by
most humans from 0.02 to 0.1 (iL/L. C4HioS has a reported odor threshold of <0.001 (iL/L (Chevron
Phillips, n.d.). (CH3)2S has an odor threshold of approximately 0.001 (iL/L (Bayou Engineering, 2004);
(CH3)2S2 has an odor threshold of 0.008 (iL/L (Bayou Engineering, 2007).
U.S. EPA (2008) reported uncontrolled LFG data on several RSCs, in addition to H2S. Table 2-10
summarizes the data from U.S. EPA (2008) for several RSCs. Samples of LFG were collected from
MSW landfills, and the sample collection point was from the main GCCS header pipe.
Table 2-10. Summary of Measured RSC Concentrations From MSW LFG (U.S. EPA, 2008)
Compound
CHsSH
CsHsS
COS
CS2
(CH3)2S
(CH3)2S2
Minimum
(ML/L)
9.8 x10-4
3.75x10-5
1.04x10-4
2.92 x10-4
7.51 x10-3
2.29 x10-4
Maximum
(ML/L)
4.05
1.22
0.275
0.353
14.7
0.435
Mean
(ML/L)
1.37
0.175
0.122
0.147
5.66
0.137
Standard
Deviation (uL/L)
0.955
0.26
7.12x10-2
8.74x10-2
0.383
0.103
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Lee et al. (2006) measured RSCs at 10 C&D landfill sites in Florida. Samples were collected above the
landfill surface, and from gas collection pipes and subsurface vapor probes. H2S was typically found in
significantly greater concentrations than the other RSCs. However, at one site where samples were drawn
from LFG wells, concentrations of COS (22 (iL/L) and CHsSH (85 (iL/L) exceeded that of H2S (average
of5.9jiL/L).
While the presence of all RSCs can create potential odor and operational issues (with respect to gas
collection and energy utilization) at landfills, the relative and persistent dominance of H2S indicates that
in most cases the measurement of H2S will likely provide appropriate information to site operators
regarding the presence and magnitude of potential odor or other issues related to RSCs at a landfill.
3. Methods to Prevent and Control H2S Emissions
Knowledge of the factors that contribute to H2S formation is essential to preventing its formation, and
strategies to actively reduce emitted H2S concentrations are detailed in this section. Formation of H2S in
landfills may not be avoidable due to varying constraints; thus it is critical to discuss strategies to control
H2S emissions once the gas is formed. There are several strategies to prevent and control H2S that have
been explored at the research level and in practical application. Given the differences in site
characteristics and regulatory schemes that landfill sites may be subject to, an integrated approach that
employs one or more of the strategies in this section, coupled with effective site-specific BMPs, may
yield effective results.
3.1 Methods to Prevent H2S Formation
3.1.1 Diversion of Drywall and Limiting SCU2" Content of RSM
The diversion of drywall from disposal has been recommended as a measure to prevent H2S formation in
landfills (CalRecycle, 2007; FDEP, 2011). In some cases, landfills have instituted bans on the disposal of
drywall except for small amounts. For example, a landfill in Vancouver, Canada is subject to a bylaw
created by the Greater Vancouver Sewerage and Drainage District Act (GVSDDA) of 2012, which states,
in part:
No person shall dispose of any Gypsum at a Disposal Site: (a) except at a Recycling
Area designated for Gypsum; and (b) unless the Load of Gypsum weighs one-half (1/2)
tonne or less.
Metro Vancouver uses two elements in addition to the disposal ban to facilitate compliance and
appropriate management of gypsum drywall. First, an economic disincentive for delivering gypsum
drywall to the landfill was established. Generators that bring prohibited gypsum drywall to the landfill
are assessed a minimum surcharge of $50, plus the cost of removal, cleanup, or remediation. Loads that
contain banned materials are assessed a 50% tipping fee surcharge. Second, Metro Vancouver provides
generators with information on a drywall recycling facility where scrap drywall can be delivered
(provided the material does not contain asbestos) (Metro Vancouver, 2012).
A variety of recycling markets have been developed for gypsum drywall, including for purposes such as
agricultural soil amendments and manufacture of new drywall, so the increase in the diversion of drywall
for recycling would be expected to reduce the amount of drywall that is deposited into landfills. As with
any recycled product, the ability to effectively recycle a waste component depends on market demand, the
cost of virgin materials or materials being replaced by the recycled product, disposal costs, transport
costs, and other factors.
Another practice that may reduce H2S emissions at disposal facilities that accept RSM is to limit the SO42"
content of the RSM delivered to the facility. Musson et al. (2008) developed a method to establish SO42"
content in RSM, which can be used by C&D recyclers to track performance related to gypsum drywall
removal and provides receiving facilities with important data to understand the SO42" content (and
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therefore potential to produce FfcS) in RSM that is accepted. In some states (e.g., Massachusetts and New
Hampshire), the removal of gypsum drywall at the front end of the C&D recycling process is required
where feasible. Landfills may also develop specifications for RSM that include sampling procedures and
sampling personnel training requirements, and chemical limits of the RSM, which may include SC>42.
While the practice of separating drywall and limiting the SO42" content of RSM produced by C&D
recycling facilities should decrease the amount of reducible sulfur entering a landfill, the specification of
maximum SCV limits at a landfill that uses RSM may not necessarily prevent all H2S emission problems.
For example, Carlton et al. (2005) reported that an MSW landfill that accepted C&D fines specified and
routinely met a SCV limit of 3%, but odor problems at the facility persisted anyway. Another
consideration for operators that specify SC>42 limits in RSM is that the results can be somewhat variable
between C&D recyclers and even at the same recycling facility. For instance, Anderson et al. (2010)
summarized SCV content data from eight C&D recyclers in Massachusetts and found the mean SCV
content of C&D fines to range from 1.6% to 8.7%. Data presented by Anderson et al. (2010) for one
C&D recycling facility over a 2-year sampling period showed a SCV content range from approximately
0% to 15%. Anderson et al. (2010) also noted data from a landfill that monofilled C&D fines and layered
the fines with material to reduce odors, which suggested some effectiveness, but further study was needed
to more closely evaluate this technique.
3.1.2 Moisture Control
Minimization of moisture contact with gypsum-containing waste is a key to minimizing FfcS generation;
thus, practices to reduce the infiltration of moisture into the waste are expected to reduce the production
and emissions of FfcS - note that many of these practices can help to reduce the emission of other gases
that are not in the form of a reduced sulfur compound. These practices, which are summarized in Table
3-1, are expected to apply to both C&D and MSW landfills. It is noted that some of the practices (such as
minimizing the size of the working face) are more commonly required in MSW landfill permits.
Table 3-1. Summary of and Discussion of Moisture Control and Cover Soil Use Techniques to
Minimize the Production and Emissions of
Landfilling
Practice
Minimizing the
Landfill Working
Face
Working Face
Grading
Landfill Phasing
Using Daily or
Weekly Cover
Discussion
Reducing the size of the working face reduces the potential for surface water to contact and
percolate through the waste mass. A smaller working face also reduces the amount of cover
soil needed, thus the quantity of soil needed would be less, which would be a benefit at sites
that use RSM as daily cover. A smaller working face would also reduce the area of waste
open to the atmosphere, which would be expected to reduce odorous gas emissions
compared to a facility with a larger working face.
Grading the active face for drainage helps to avoid ponding of water on the landfill surface
and thus encourages runoff.
The use of intermediate cover, particularly on side slopes as a landfill is built up, would be
expected to encourage surface water runoff and reduce the amount of moisture that
infiltrates into the waste mass.
Many states do not have a regulatory minimum requirement to apply cover soil at C&D
landfills. The use of cover soil can help reduce the migration of liquid into and through the
waste, and can act as a barrier and removal mechanism for hhS, depending on the cover
material used. Soil has the potential to absorb released hhS that passes through the cover,
(continued)
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Table 3-1. Summary of and Discussion of Moisture Control and Cover Soil Use Techniques to
Minimize the Production and Emissions of H2S (continued)
Landfilling
Practice
Discussion
Disposal Practices
with Drywall
Instituting unique practices at landfills that accept gypsum drywall may help to mitigate
issues that can occur when the materials are exposed to moisture. Options may include:
• Placing loads of material containing drywall in areas of the active landfill face that
are at a higher elevation, which would decrease the potential of moisture contact
compared with placement in a low-lying area on the active face.
• Immediately placing additional waste or a cover (e.g., temporary tarp or soil
cover) on top of newly-placed loads that contain gypsum drywall to reduce the
likelihood of contact with stormwater.
• Segregating received drywall to distinct areas and perhaps making note in
operations records of areas where larger amounts of drywall were placed (similar
to how landfills that accept asbestos make note of incoming quantities and
disposal location). This practice would be expected to consolidate locations
where hbS may be formed and facilitate future hbS mitigation, if needed.
Run-On and Run-
Off Controls for
Stormwater
The use of run-on controls will prevent stormwater from encroaching onto or into the
landfill, while run-off controls help to divert stormwater to appropriate stormwater
management areas.
Use and Proper
Operation of
Leachate Removal
and Treatment
Systems
Leachate build-up on the bottom of landfills can occur if there is naturally-occurring low
permeability material beneath the waste, and can occur with an improperly functioning
leachate collection system. As an example of the impact that liquid levels can have on
production, Bergersen and Haarstad (2008) observed in the laboratory an approximately
8-fold difference in hhS off-gassing from effluent from submerged MSW mixtures
containing crushed gypsum board compared to MSW mixtures with crushed gypsum
board with a low water content.
3.1.3 Bacterial Inhibition
The use of bacterial inhibitors to reduce the proliferation of SRBs has been evaluated at the laboratory
scale. Isa and Anderson (2005) evaluated the use of molybdate (MoO42~) as an SRB inhibitor in a
continuous feed anaerobic digestion process. The findings showed that SRB and CH/rproducing bacteria
were inhibited; thus, such a solution may not be appropriate for MSW landfills that are recovering LFG
for energy. Xu et al. (2011) evaluated the use of different chemical inhibitors at the laboratory scale,
including sodium molybdate on the production of H2S from gypsum drywall. The results showed that a
three orders of magnitude decrease in H2S concentration was observed when the inhibitor was used,
which was attributed to the development of pH conditions unfavorable to biological growth. Overall, the
use of bacterial inhibitors has not been examined on a field scale and further evaluation is needed to
assess the effectiveness of a bacterial inhibitor on H2S production and potential environmental impacts
(such as resultant leachate concentrations and subsequent potential impact to groundwater).
3.2 Methods to Control H2S Emission
3.2.1 Leachate Management
Once leachate is generated in a landfill, it is either collected in a leachate drainage system or infiltrates
into the groundwater (in the case of unlined landfills). H2S contained in leachate volatilizes in accordance
with Henry's law due to new concentration and pressure gradients outside of the landfill. Profumo et al.
(1992) demonstrated that leachate can be a significant source of H2S. Thus, the identification and control
of leachate (e.g., seeps at side slopes, at the landfill surface, or at the toe of the landfill) may help to limit
exposure of raw leachate to the atmosphere and thus reduce the potential for H2S to volatilize into the
atmosphere. An additional consideration is acknowledging the potential hazardous atmospheres that can
form in areas where leachate may accumulate, including gas wells, leachate sumps and cleanout lines, and
tanks, and ensuring that landfill personnel are aware of these areas and the potential for H2S to be present.
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Oxidation of H2S inside of leachate containment areas such as sumps can prevent the eventual off-gassing
of H2S; an oxidizing agent (e.g., hydrogen peroxide) oxidizes H2S to elemental sulfur or SCV", depending
on pH. Also, aerated leachate ponds (e.g., using floating aerators) are commonly used to lower BOD and
COD levels in leachate, which can oxidize RSCs as well.
3.2.2 Cover Soil Amendments
Research regarding various landfill cover amendments to reduce H2S through precipitation, adsorption, or
oxidation has been conducted at the laboratory and field scale. Prior to consideration of a soil
amendment, it should be noted that the use of natural soils has shown the ability to decrease the
concentration gradient (one of the main driving forces behind H2S emissions, as described in Section 2)
and thus provide time for H2S to be adsorbed or removed. For example, Xu et al. (2010) observed up to a
60% removal capacity of H2S by natural soils in a set of field experiments in Florida.
In some cases, the use of natural soils may require supplementation to further enhance the removal or
mitigation of H2S. Below is a summary of cover soil amendments that have been used at the laboratory or
field scale and shown to decrease H2S emissions. Note that the effectiveness (short-term and long-term)
depends on the amendment blend that is used and specific site characteristics such as source H2S
concentration, atmospheric characteristics, and landfill characteristics. The materials list provided in this
section represents examples of amendments reported in the literature and is not intended to represent
guidelines for design. Some of the amendments listed could potentially be used at landfills other than
those that accept C&D debris and MSW (such as an industrial waste facility that accepts paper mill
sludge); however, factors such as waste mass stability should be considered when applying cover
amendments to industrial waste facilities. The selection and use of a cover soil amendment must be made
with consideration of numerous factors, including economics, site permit conditions, and other relevant
site characteristics.
• Ammonium nitrate fertilizer. Sungthong (2010) and Sungthong and Reinhart (2011)
evaluated the removal of H2S at the lab scale by ammonium nitrate fertilizer, which
proceeded under the autotrophic denitrification process. An analysis of an example 10-acre
MSW landfill (modeled after an actual operating facility) using measured H2S concentrations
(which had H2S concentrations in collected LFG ranging from 480 to 2,800 (iL/L) suggested
that the application of 157,000 kg of 34% nitrogen fertilizer could sufficiently remove the
anticipated 15-year emission amount of 80,900 kg of H2S.
• Coal ash. CMRA (n.d.) reported that a mixture of 30% coal ash and 70% RSM helped to
control H2S emissions by an order of magnitude in a C&D cell. New Hampshire evaluated
the use of a 50% coal ash and 50% RSM blend that indicated H2S reduction (NHDES, 2004).
In most cases, the use of coal ash would likely only be allowable at an MSW landfill because
of restrictions on using/disposing ash in many C&D landfills based on a review of state
regulations (U.S. EPA, 2012b).
• Compost/biocover soil. Xu et al. (2010a) showed that a yard waste-derived compost in a
field study at a C&D landfill attenuated H2S more effectively than sandy soil. Materials
similar to composted yard waste such as chipped waste wood or bark may also be effective.
Bergersen and Haarstad (2008) used organic filter materials and observed H2S removal
capacities of 215 and 387 mg S/kg for spruce bark and wood chips, respectively.
• Concrete fines. Plaza et al. (2007) showed that concrete fines (those smaller than 2.5 cm)
reduced H2S concentrations by 99% in a laboratory column study. At the field scale, Xu et
al. (2010a) covered plots at a C&D debris landfill and observed a 90% reduction in H2S
levels, which was attributed to a pH shift caused by the high-pH concrete fines and
adsorption of H2S onto the fines.
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• Fuller's earth. This material is a clay-like substance that has been used as an absorbent in
numerous applications (e.g., cat litter). Commercial products and patents have been
developed that are Fuller's earth-based. Lab-scale test results presented in USPTO (2005)
indicate approximately 0.2 mg of H2S could be removed (to levels at a normal human odor
threshold) per g of a blend comprised mostly of Fuller's earth, or approximately 65 to 75 tons
per acre of landfill surface for a 2-cm thick layer.
• Lime. Plaza et al. (2007) showed that lime-amended soil (5% by weight mixture) removed
H2S substantially in a laboratory column study. Xu et al. (2010a) conducted a field study that
evaluated a 1% and 3% by weight lime-soil mixture on the surface of a C&D landfill. In both
cases, the lime-amended soils were shown to attenuate H2S, which was attributed to changing
of pH conditions and physical removal. Sungthong (2010) calculated that approximately
176,000 kg of hydrated lime would be needed to create a 1% (wt) blend with a 2-ft thick
cover soil to attenuate expected H2S emissions from an example 10-acre landfill (described in
the ammonium nitrate fertilizer section above) with a 15-year H2S emissions amount of
80,900 kg.
• Steel tire shreds. Anunsen (2007) showed that Ml steel from a tire shredder placed near
passive LFG vents at an MSW landfill showed the attenuation of H2S over a range of flow
rates. Xu et al. (201 Ob) showed substantial attenuation of H2S (from 100 (iL/Lto 1 (iL/L)
using tire-derived steel in a simulated landfill cover.
• Metallic filter materials. Metallic filter materials removed H2S (600-1,200 (iL/L) in
laboratory experiments where H2S was generated from submerged waste materials with and
without gypsum drywall in column reactors (Bergersen and Haarstad, 2008). Iron oxide,
iron-rich sewage sludge compost, and a 3:1 mixture of bottom ash and iron oxide removed
983 mg S/kg, 762 mg S/kg, and 3,345 mg S/kg, respectively.
3.2.3 Capping Systems
Capping a landfill with a low-permeability layer can help to remediate H2S emission by both curbing
production and preventing emissions from entering the atmosphere. Landfill capping systems limit or
prevent infiltration of stormwater (and thus the production of leachate) into the waste. Once H2S has been
generated in a landfill, the cap systems provide a barrier to uncontrolled venting of LFG. The use of a
capping system in combination with a GCCS minimizes escape of H2S gas. The deployment of capping
systems in combination with an active GCCS has been recommended as a BMP for H2S control at both
MSW and C&D landfills (Waste Management, 2005; Massachusetts DEP, 2007). Capping systems are
often part of a final or intermediate cover at landfills, and both will be discussed in this section.
Discussion regarding the integration of a capping system with an active GCCS is presented in
Section 3.2.5.
Intermediate cover is intended to provide a greater barrier between the waste and the atmosphere than
daily cover and in addition provide cover to an area that will not to be filled over for an extended period
of time and may need to be driven over in order to fill the landfill sequentially. While daily cover
typically consists of a six-inch layer of soil (or approved equivalent), intermediate cover is typically
thicker (e.g., 1 ft) and is normally compacted to allow ease of access. Thus, intermediate cover with a
greater thickness than a typical daily cover is expected to provide the benefits described in Section 3.2.2
for soil covers, but also potentially facilitate LFG collection as well. Temporary membranes (synthetic
materials) can also be utilized as an intermediate cap prior to the installation of a final permitted capping
system. In cases where intermediate covers cannot be constructed at a slope to allow for positive
drainage, supplemental piping and drainage infrastructure may be needed to prevent ponding of
stormwater on the landfill surface.
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The components of final cover systems vary depending on the type of landfill and the specific conditions
of a disposal facility's permit. Low-permeability final cover normally consists of the following layers
(from top to bottom): soil layer capable of supporting vegetation, drainage layer (e.g., geonet overlain by
geotextile to prevent clogging), barrier layer, grading layer (this is sometimes overlain by a high-
permeability layer, such as coarse sand, to allow the transmission of LFG to collection points). The
barrier layer can consist of either synthetic (e.g., HDPE) or natural materials (e.g., low-permeability
compacted clay). For facilities that do not require a low-permeability final cover, the final cover
configuration typically consists of (from top to bottom) a soil layer capable of supporting vegetation and a
soil layer to provide a buffer distance between the top of the final cover and the top of the waste mass
(e.g., 2-ft thick).
At facilities where H2S emissions are problematic, the installation of final cover as soon as final waste
filling grades are reached can aid in controlling H2S when coupled with some form of LFG controls. This
practice may or may not be accelerated based on permit requirements, and the decision to deploy a final
cap earlier than a facility's permit requires may be necessary for practically handling H2S emission
problems in some cases.
3.2.4 Odor Neutralizers
Odor neutralizers can be utilized to mask or mitigate odors from H2S. Odor neutralizes are chemicals
that react with H2S to form a nonodorous compound, or may simply act to mask odors. Other odor-
neutralizing agents work to encapsulate materials and thus block odors from escaping. Odor neutralizers
are often misted in a spray, which is then applied at landfills to the working face, near the working face,
or near or at the site perimeter, depending on where odor concerns are present.
Examples of chemicals that act as H2S odor neutralizers include bleach, sodium bicarbonate, ammonium
bicarbonate, magnesium bicarbonate, caustic soda, amines, and other proprietary chemicals. Neutralizers
are often sold in concentrated form and are diluted upon deployment; in some cases, dilution ratios can be
controlled, depending on the severity of odor issues or the area being managed.
Odor neutralizing chemicals in aqueous form can be applied via conventional agricultural sprayers, vapor
diffusion systems that use heat to vaporize chemicals (essential oils) and then blow them through a
perforated pipe, water trucks that employ spray bars and hoses for heavy working face product
application, and fogging or industrial misting systems. Passive odor neutralizers (such as deodorizing
sleeves that can be hung at different areas at a site) may be used as well, where a solid granule or powder
neutralizes the odor.
In general, odor neutralizers are considered temporary measures as the products typically do not prevent
the production of odorous compounds.
3.2.5 LFG Collection and Treatment
LFG collection involves the installation of collection devices (e.g., wells) into the waste to control the
flow of LFG, although LFG controls may also include collectors located beyond the perimeter of the
waste. LFG can be passively vented or actively controlled. No federal standards for active LFG control
exist for C&D landfills, but federal standards (e.g., those found in the New Source Performance Standards
for MSW Landfills, 40 CFR Part 63 Subpart WWW) mandate active gas controls once an MSW landfill
reaches a certain size or emission rate of nonmethane organic compounds (NMOC). H2S generated in
landfills is considered a trace component of LFG, and the installation of an active GCCS solely to control
FfcS is not very common because of the extensive design, permitting, and construction needs associated
with an active GCCS.
Collected LFG can be vented to the atmosphere (and typically routed through treatment media or
individual destruction devices), routed to a temporary or permanent flare station to combust the collected
LFG, or utilized for energy production. Passive vents within the waste could be embedded within a
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treatment medium as well (e.g., wood chips), which could provide an added opportunity to remove odor-
causing compounds before the gas is vented to the atmosphere or routed for further treatment. Active
GCCS systems use compressors or vacuums to create a pressure gradient to route LFG to a collection
point. The number and spacing of collection wells depends on waste density, pressure gradients required,
and LFG production expected (which depends on the composition of the waste). The U.S. EPA Landfill
Methane Outreach Program reports that more than 500 MSW landfills have an LFG to energy project and
more than 500 landfills are candidates for an energy project.
Active LFG control at C&D landfills may be complicated by the fact that substantial quantities of other
gases such as CFL are not produced, which is a reflection of the types of waste normally deposited in
C&D landfills (refer to Section 2.5 for discussion of waste composition at C&D landfills). In cases where
active LFG controls are used at C&D landfills, supplemental fuel may be required to provide enough
BTU content to combust the gas (e.g., an active GCCS at a landfill in New York used natural gas as a
supplemental fuel (McCarron, 2007)). Solar spark flares have been used in cases where lower LFG flow
rates or CFL concentrations are present (e.g., at C&D landfills, in areas of MSW landfills that do not yet
require active control, or at areas of landfills where LFG may build up such as leachate lines).
As mentioned previously, high levels of H2S in LFG can be problematic in LFG to energy projects—for
example, Lopez (2012) indicates that the frequency of maintenance and engine overhauls at energy
projects that convert collected LFG to electricity is greater when H2S concentrations are greater because
of wear and corrosion of engine parts. High H2S concentrations in LFG may also void or limit
manufacturer warranty (General Electric, 2009). Rasi et al. (2011) reported that a recommended
maximum H2S concentration for biogas (including LFG) used in boilers and internal combustion engines
is 1,000 (iL/L. GE Jenbacher recommends H2S limits of 700 mg/10 kWh and 1,200 mg/10 kWh for LFG
engines with and without catalytic converters, which equate to 245 (iL/L and 419 (iL/L, respectively
(General Electric, 2009). In cases where LFG is cleaned up to remove CO2 and other constituents for use
as a vehicle fuel or for delivery to natural gas pipelines, H2S concentrations of less than 4 (iL/L are
normally required (Wentworth, 2009).
Collected LFG with a high concentration of H2S can result in the emission of SO2 following combustion
at a LFG destruction device. SO2 is a primary pollutant subject to national ambient air quality standards
in the United States, and Title V operating air permits at MSW landfills may have limits on the emissions
of SO2. In cases where high LFG collection rates and high concentrations of H2S are present, the permit-
specified SO2 emission limits could be reached, thus potentially requiring the implementation of a system
to reduce H2S concentrations prior to combustion of the LFG. For example, a study at a large MSW
landfill in Virginia estimated that the facility's Title V SO2 emission limit of 240 tons per year could be
exceeded with a LFG collection rate of 8,000 standard cubic feet per minute and an H2S concentration of
770 (iL/L (Tennant, 2012).
A variety of treatment technologies are available to reduce the concentration of H2S in collected LFG.
Table 3-2 presents a summary of LFG treatment technologies specific to H2S removal or reduction.
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Table 3-2. Summary of Treatment Technologies to Reduce hhS Concentrations in Collected LFG
Treatment
Technology
Liquid Treatment
(Scrubbers to treat
gas flow)
Liquid Treatment
(Scrubbers to treat
gas flow)
Solid Adsorption
Treatment
Chemical Process
Biological
Processes
Further
Classification
Alkaline Solutions
Amine Solutions
Nitrite Solutions
Metal Solutions
Activated Carbon
Ash
Metal
Oxides/Catalysts
Oxidizing Agents
Sulfur Oxidation
Specific Chemicals, Mechanisms, Results
Caustic Soda (NaOH)
• NaHS or Na2S solid salts are formed (Siemak, 1985)
Other hydroxides (KOH, Kl)
Carbonate Solutions (Na2COs, MgCOs)
Sulfaclear®, Almont 6,6B, 6F®
Methyl Di-ethanol Amine (MDEA) (Pandey 2005)
3H2S + NaNO2^ NHs + 3S +NaOH
Metal SO42' Solutions
• CuSO4, ZnSO4, FeSO4 examined by ter Maat et al. (2005) in
laboratory
• Precipitates metal sulfide, metal carbonate, or metal
hydroxide (pH dependent)
• CuSO4 purified biogas in a pilot scale project (85% removal
of influent H2S at 1 70 ul_/L)
SulFerox®
• H2S reacts with aqueous ferric iron, forms S°
Norit ROZ3®
• Steam activated carbon, designed for H2S and mercaptan
removal
• Can be diluted with less selective, less costly AC species
(Norit RB4W) for similar H2S removal (up to 70% dilution)
(Mesciaetal. 2011)
• Field scale experiments showed H2S (245 uL/L) removal to
1 uL/L; removal of 71.99 ghhS/kg AC (30% ROZ3) (Mescia
etal. 2011)
MSW bottom ash
• Removed H2S (100 ul_/L), CHsSH (4 ul_/L), and (CH3)2S (30
uL/L) from field LFG; mass removals of 3 g, 44 mg, and 86
mg per kg ash, respectively. Contact time played a large role
(Ducomet al. 2009).
Iron sponges
Produces metal sulfides
• Pyrite (FeS2), phalerite (ZnS), Molybdenite (MoS2)
SulfaTreat®
Hydrogen Peroxide (H2O2)
• Can form elemental sulfur or SO42" (pH dependent)
ThioPaq®
• Biologically mediated HS' to elemental sulfur (S°) after
alkaline scrubbing
• Regenerates caustic soda for reuse (Tennant 2012)
Bio-Scrubber®
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4. Site Investigation and Monitoring Techniques
4.1 Site Inspection Procedure Considerations
Site investigations may occur as part of routine operations or in response to an odor complaint. If odor
complaints are received at a landfill, pertinent information about the complaint (e.g., location of
complaint, time of day, weather conditions at the time of complaint, assessment of site conditions at the
time of the complaint) should be recorded.
Multiple states have developed BMP or guidance for the evaluation of odor that may be emanating from a
landfill and/or require that landfills maintain their own odor management plan to address odor. The
practices from several BMP guides were evaluated and the key elements related to site inspection
considerations for landfill personnel are summarized below.
• Identify any potential sources of odor from accepted wastes (e.g., dead animals, gypsum
drywall (bulk or size-reduced), processing of yard waste, biosolids, other industrial wastes).
• If a GCCS is present, evaluate areas where elevated temperatures are present, as these may be
areas of higher decomposition and potential areas of H2S production and emissions.
• Perform site inspections during early morning or late evening, when odors are most likely to
be observed.
• Use monitoring instruments that are properly calibrated to the range of H2S concentrations
expected, and use such equipment consistently with manufacturer specifications.
• Inspect and monitor for H2S along the site perimeter, particularly paying attention to site
topography as H2S may settle in low-lying areas.
• Monitor for H2S near and downwind of the working face.
• Record all measured H2S concentrations and the locations where they were measured.
• Inspect for any leachate seeps or ponded leachate, document and address on- and off-site
structures where leachate may migrate and emit H2S gas, causing exposure to workers and
nearby residents.
• Document information regarding weather conditions and area(s) of the site inspection,
including (but not limited to):
o Date and time
o Weather conditions
• Temperature
• Wind speed and direction
• Cloud cover
• Ongoing or recent precipitation events
o Name of person conducting inspection
o Areas inspected (written description and/or map)
o Locations or observations from other potential nearby sources of odor or H2S (e.g.,
wastewater treatment plant)
• Maintain documented site inspection records on site.
Another important consideration related to site monitoring is awareness of confined spaces. Confined
spaces are generally defined as areas with limited entry or exit that are not designed or intended for
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continuous human occupancy. Confined spaces have the potential for hazardous atmospheres, including
explosive gas concentrations, concentrations of gases that are toxic to humans, and low oxygen.
Examples of confined spaces at C&D and/or MSW landfills include vaults, tanks, pipes, storage bins,
sumps, and trenches.
Many landfills are required to have confined space entry plans intended to prevent someone from entering
a toxic/oxygen-deficient environment with the potential for asphyxiation. These plans emphasize the
buddy system, where if one is entering a confined space, another person stands by ready to aid an escape
from the confined space; in some cases a harness or other safety equipment may be required (Bolton,
1995). At a minimum, site personnel should be trained to understand how to identify a confined space
and know to not enter a confined space unless in accordance with a confined space entry plan.
4.2 H2S Monitoring Techniques
Because of the low odor threshold associated with H2S, the detection of odors by site personnel may serve
as an initial indication of H2S emissions at a site. However, as discussed previously, H2S present at
higher concentrations may not be detectable because of the olfactory paralysis that can occur. OSHA
(2005) recommends that workers not rely on the sense of smell to indicate the continuing presence of H2S
or to warn of hazardous concentrations. Monitoring of H2S concentrations can be part of an odor or H2S
evaluation plan. A variety of instruments have been developed that detect H2S over a range of
concentrations for a variety of purposes (e.g., assessing human exposure levels, measuring concentrations
in confined spaces or gas collection wells, measuring concentrations in ambient air).
It is important when selecting a device that the purpose of the monitoring is clear and that the appropriate
limitations (e.g., detection limits, potential interferences) of a given instrument are understood so that the
data gathered meet the H2S monitoring program's objectives. A presentation and discussion of common
types of H2S monitoring devices is presented in Table 4-1.
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Table 4-1. Examples of hhS Monitoring Devices, Applications, and Limitations
Sampler Type
Applications and Limitations/Interferences
Personal
badges
Disposable devices normally used for detecting acute hhS exposure. Clips on clothing or fits
in a pocket near the wearer's breathing zone. Can produce visual, vibratory, or audible alarm
upon exceedance of a set standard (10 uL/L is common) or simply produce a color change.
hhS reacts with an indicator layer (e.g., lead acetate). Visual color comparison to exposure
dose color (in uL/L*hr) is used to calculate average concentration by dividing this value (in
uL/L*hr) by exposure time. Some can detect other gases in addition to hhS.
Temperature limitations may be an issue (one sampler reported in the 16 °C - 36 °C range).
They can also be used as stationary monitors over limited periods of time simply by affixing to
a pole with the detector facing the emission source.
Typical hhS range: 1-240 uL/L*hr
Example products: Industrial Scientific Gas Badge Pro and Gas Badge Plus, Chromair Gas
Monitoring Badge, Safeair Gas Monitoring Badge, BW Honeywell Gas Alert Clip Extreme hhS
Monitor
Multi-gas
meters
Standard multi-gas samplers typically use an active sample pump to draw gas into the inlet
orifice. Used when monitoring of other gases is necessary (e.g., ChU, CO2, 02, CO).
Because standards often exist for ChU or CO concentrations on site and at the perimeter
boundary (i.e., a certain percentage of the LEL) monitoring of hhS can be conducted in
conjunction with these gases. Meters are typically battery-operated and use a microprocessor
to display concentrations on a display and can often store data via a data logger; some have
alarms that sound at significant concentration levels. Regular calibration is necessary. More
elaborate systems are available that operate using an analyzer with a near-infrared laser that
quantifies spectral features of molecules in a sample gas passed through an optical
measurement cavity. This technology also allows for vehicle mounting and simultaneous gas
measurement and mapping of hbS and ChU concentrations.
Typical hbS range: 0-100 uL/L, although other ranges are available
Example standard multi-gas samplers: Gas Alert Mac XTII, MSA Altair 4X Multigas Detector,
MultiRAE Plus 4 Gas Meter, RKI GX-2003 Multi Gas Monitor, RKI Eagle 2,
Example near-infrared laser gas analyzer with mapping capability: Picarro Model G2204
Electrochemical
cells/pods
Sensors designed for a specific gas measurement. Operate through diffusion of hhS (or other
gas of interest) into measurement cell where an oxidation (in the case of hhS) or reduction
reaction at the working electrode occurs. Working electrode is typically contained in an acidic
solution. A measureable voltage is produced upon oxidation; the measured gas concentration
is linearly proportional to the electrical output of the gas sensor.
Other gases (NO, hh, etc.) can cause some interference. Can also utilize a reference
electrode that eliminates interference from side reactions. Low temperatures (
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Table 4-1. Examples of hhS Monitoring Devices, Applications, and Limitations (continued)
Sampler Type
Applications and Limitations/Interferences
Dedicated
meters
Specialty meters that can detect hhS over a range of low and intermediate concentrations.
Technology used includes gold film sensors that work via selective adsorption and desorption.
Interference may be caused by some constituents (e.g., chlorine, ammonia, NO2, and
mercaptans) but filters are available to reduce interference. Detection limits on several of the
meters were reported as 0.003 uL/L. Meters can be set for either a single sample or survey
mode; survey mode provides quicker source detection. Another technology includes the
Honeywell Chemcassette system, which uses an optical scanning system to detect a gas via
color change. Other technologies include pulsed fluorescence, which converts hhS to SO2 and
measures the SO2, thus the measurement of hhS is indirect.
Typical hhS Range: 0.003-50 uL/L
Example products: Arizona Instruments Jerome J605, Jerome 631-X, Jerome 631-XE,
Honeywell Single Point Monitor, Thermo Scientific 451 i
Remote
systems
These systems utilize detectors that can be placed in an area where continuous, remote
monitoring is desired (i.e., site perimeter boundary, confined spaces onsite). Remote sensor
units are either wired or wirelessly connected to a controller. Detectors can be self-powered
(e.g., solar, battery) and selected based on the desired range of H2S concentrations to be
measured. Systems can be changed or expanded to include many monitoring points.
Electrochemical sensors are sometimes used for the sensor components. Visual and audible
alarms can be produced upon exceedance of a given gas concentration. It is recommended
that fixed monitors be placed in low spots due to the H2S-specific gravity. These dedicated
meters are typically expensive as they require infrastructure installation.
Example products: Rig Rat
Sensor Heads
Portable Area Monitoring System, RKI Beacon/Fixed System
Colori metric
detector tubes
One-time use tubes (with printed H2S scales on the tube) specific to a certain gas and
concentration range is opened (tips broken) and inserted into a pump. Ambient air or gas
(e.g., collected in a nonreactive sample container) to measure H2S is pumped through the
tube. Measurements are indicated by the length of the color change in relation to the scale
printed on the tube; adjustment factors for sample volume, temperature, and humidity can be
applied using manufacturer datasheets. Tubes do not require calibration and may be subject
to some interferants, depending on the tube used.
Typical H2S range: Varies depending on product; range-specific tubes are sold (e.g., low,
high, ultra-high). Standard range of 25-250 uL/L. Passive colorimetric detection tubes can
also be used for longer-term time-weighted average measurements.
Example products: Drager Detector Tubes, RAE Systems H2S Colorimetric Gas Detection
Tubes
Electronic
noses
These devices contain an array of sensors that quickly analyze multiple molecules at once;
they are utilized in the food, beverage, and perfume industry extensively. They generally
consist of a wide array of technologies, including conducting polymer sensors, sintered metal
oxide semi-conductors, catalytic metals, organic semi-conductors, surface wave gas sensors,
quartz crystal microbalance, electrochemical, smell-seeing, and field effect transistors (Otles
2008).
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5. BMP Framework to Manage hkS Emissions from Disposal of
Gypsum Drywall
Most permitted landfills are required to develop and maintain operations plans that cover a wide range of
issues and considerations. Normally, odor management is addressed in broad landfill operations plans,
but often do not require the background and detail needed to address the potentially severe issues caused
by elevated H2S emissions. Thus, in some cases the development of a site-specific BMP guide may be
necessary to allow landfill owners and operators to understand the specific issues and challenges
associated with H2S, provide the landfill operators with valuable documentation that can be used to
demonstrate the procedures used to address H2S emissions, and provide direction to landfill staff so that
issues encountered with H2S emissions can be observed and managed more rapidly. Figure 5-1 presents
a simplified flow chart that can be used by landfill owners and operators as a starting point to develop a
site-specific BMP guide for H2S emissions management. Each step presented in Figure 5-1 is described
in more detail below.
3, Perform
Corrective
4. Internal
Audit and
I '
Figure 5-1. Framework for Developing a BMP Guide for Managing hhS at C&D or MSW Landfills
A discussion of each of the framework elements is provided below.
1. Identify the BMP guide objectives. Each landfill's site-specific considerations should be
accounted for when the BMP guide is developed. For example, a landfill that accepts large
amounts of drywall but has never had odor issues or H2S emission issues may structure the
BMP guide in a way that includes measures to help prevent H2S emissions. This would be in
contrast to the structure of a BMP guide for an MSW landfill that beneficially uses collected
LFG and has not had odor issues but has high H2S levels in the collected LFG. In this case,
the guide may be focused on monitoring and maintenance associated with an H2S treatment
system.
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2. Describe the management practices to be employed. The BMP guide would identify key
information, such as responsible parties and lines of communication for maintenance,
monitoring, and inspections; types of equipment to use for monitoring; frequency and
location(s) of IrkS monitoring (including documentation requirements); and an enumeration
of practices that the site adopts based on site-specific conditions to mitigate or otherwise
manage IrkS emissions. The conditions and ultimately the management practices employed
should consider the variety of sources and conditions that may lead to IrkS production and
emission (as described in Section 2) and the procedures that can be used to reduce emissions
(as described in Section 3). The description of management practices should also identify
action levels that are tailored to the facility's needs, which will be used in conjunction with
corrective actions (Step 3 below).
3. Perform corrective action. The BMP guide should discuss actions that should be taken if
H2S emissions or concentrations are greater than target levels established for the facility. The
corrective action steps may include equipment or monitoring instrument evaluation or
calibration, assessment and modification of operating practices, or other activities to mitigate
IrkS emissions.
4. Internal audit and feedback loop. The efficacy of the BMP guide should be periodically
evaluated or audited to ensure that the guide matches up with the needs of the site, as
operating needs and conditions at landfills may change frequently. The BMP guide should
include a mechanism to provide an effective feedback loop so that gaps or limitations in the
procedures for monitoring and addressing IrkS emissions can be quickly identified and
remedied.
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6. References
Agency for Toxic Substances and Disease Registry, (n.d.) Methyl Mercaptan (CHsSH). Accessed 1
November 2012, from: http://www.atsdr.cdc.gov/MHMFmmgl39.pdf
Agency for Toxic Substances and Disease Registry. (2006a). Public Health Statement Hydrogen Sulfide.
July 2006. Accessed 1 November 2012, from: http://www.atsdr.cdc.gov/ToxProfiles/tpll4-cl-
b.pdf
Agency for Toxic Substances and Disease Registry. (2006b). ToxGuide for Hydrogen Sulfide. July
2006. Accessed 1 November 2012, from: http://www.atsdr.cdc.gov/tfacts 114.pdf
Agency for Toxic Substances and Disease Registry. (2006c). Toxicological Profile for Hydrogen
Sulfide. Accessed 1 August 2013, from: http://www.atsdr.cdc.gov/toxprofiles/tp 114.pdf
Agency for Toxic Substances and Disease Registry. (2007). Technical assistance report hydrogen
sulfide in ambient air near Saufley Construction and Demolition Debris Landfill.
Agency for Toxic Substances and Disease Registry. (2009). Public Health Assessments and Health
Consultations. October 2009. Accessed 1 November 2012, from:
http://www.atsdr.cdc.gov/hac/pha/pha.asp?docid=255&pg=2
Agency for Toxic Substances and Disease Registry. (2011). Carbon Disulfide. Accessed 1 November
2012: http://www.atsdr.cdc.gov/mmg/mmg.asp?id=470&tid=84
Agency for Toxic Substances and Disease Registry. (No date). Methyl Mercaptan, General Information.
Accessed 1 November 2012, from: http://www.atsdr.cdc.gov/mhmi/mmg 139.pdf
Amini, H., Reinhart, D. (2012). Evaluating landfill gas collection efficiency uncertainty. 15th Annual
LMOP Conference and Project Expo, Baltimore, MD. January 17-19, 2012.
Amoore, J.E. (1985). The perception of hydrogen sulfide odor in relation to setting an ambient standard.
Prepared for the California Air Resources Board. Berkeley, CA: Olfacto-Labs.
Anderson, R., Jambeck, J.R., McCarron, G.P. (2010). Modeling of hydrogen sulfide generation from
landfills beneficially utilizing processed construction and demolition materials. Final Report.
Accessed 28 September 2012, from:
http://erefdn.org/publications/uploads/H2SModeling Jambeck-UNH 2-26-10 FINAL.pdf
Anunson, S. (2007). An investigation of methods to reduce hydrogen sulfide emissions from landfills.
Master's Thesis. Florida State University, Tallahassee, Florida.
Bayou Engineering. (2004). Dimethyl Sulfide. October 2004. Accessed 1 November 2012, from:
http://bavouengineering.com/images/pdf/dimethyl sulfide-dms .pdf
Bayou Engineering. (2007). Dimethyl Disulfide. June 2007. Accessed 1 November 2012, from:
http://bayouengineering.com/images/pdf/dimethyl_disulfide-dmds.pdf
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APPENDIX A
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BMP to Prevent and Control H2S and Reduced
Sulfur Gases at Landfills that Dispose of Gypsum Drywall
Table A-1. Summary of Standards and Guideline Values for Airborne H2S (adapted from US EPA
201 Oa) (all units in ppm)
Guideline
AEGL-1
AEGL-2
AEGL-3
ERPG-1
ERPG-2
ERPG-3
Acute MRL
Intermediate
MRL
EEGL
IDLH
(NIOSH)
TLV-TWA
(ACGIH)
PEL (OSHA)
TLV-STEL
(ACGIH)
Exposure Duration
10 min
0.75
41
76
50
50
30 min
0.60
32
59
100
1 hr
0.51
27
50
0.1
30
100
4hr
0.36
20
37
8hr
0.33
17
31
1
Other
0.07(0-14
days)
0.02(14-365
days)
10(24hr)
20 (peak)
15 (15 min)
Notes and definitions of terms:
AEGL. Acute Exposure Guideline Levels. AEGL-1 is the airborne concentration of a substance above
which it is predicted that the general population, including susceptible individuals, could experience
notable discomfort, irritation, or certain asymptomatic nonsensory effects. However, the effects are not
disabling and are transient and reversible upon cessation of exposure. AEGL-2 is the airborne
concentration of a substance above which it is predicted that the general population, including susceptible
individuals, could experience irreversible or other serious, long-lasting adverse health effects or an
impaired ability to escape. AEGL-3 is the airborne concentration of a substance above which it is
predicted that the general population, including susceptible individuals, could experience life-threatening
health effects or death.
ERPG. Emergency Response Planning Guideline. ERPG-1 is the maximum airborne concentration
below which it is believed that nearly all individuals could be exposed for up to 1 hr without
experiencing other than mild transient adverse health effects or perceiving a clearly defined,
objectionable odor. ERPG-2 is the maximum airborne concentration below which it is believed
that nearly all individuals could be exposed for up to 1 hr without experiencing or developing
irreversible or other serious health effects or symptoms which could impair an individual's ability
to take protective action. ERPG-3 is the maximum airborne concentration below which it is
believed that nearly all individuals could be exposed for up to 1 hour without experiencing or
developing life-threatening health effects.
Acute/Intermediate Minimum Risk Level (MRL). MRLs are developed by ATSDR and are set below
levels that, based on current information, might cause adverse health effects in the people most sensitive
to such substance-induced effects. Acute is 1-14 days exposure and intermediate is >14-364 days.
EEGL. National Research Council Emergency Exposure Guidance Levels (EEGLs).
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IDLH. Immediately Dangerous to Life and Health. An atmospheric concentration of any toxic, corrosive
or asphyxiant substance that poses an immediate threat to life or would cause irreversible or delayed
adverse health effects or would interfere with an individual's ability to escape from a dangerous
atmosphere.
TLV-TWA. Threshold Limit Value - Time-Weighted Average. The TWA concentration for a
conventional 8-hour work day and 40-hour work week, to which it is believed nearly all workers may be
repeatedly exposed each day without adverse effect.
PEL. Permissible Exposure Limit. An exposure limit that is published and enforced by OSHA as a legal
standard.
TLV-STEL. As defined by ACGIH, concentration to which it is believed that workers can be exposed
continuously for a short period of time without suffering from 1) irritation, 2) chronic or irreversible
tissue damage, or 3) narcosis of sufficient degree to increase the likelihood of accidental injury, impair
self-rescue or materially reduce work efficiency, and provided that the daily TLV-TWA is not exceeded.
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