United States «««,,-, ^* ™*
Environmental Protection EPA-600/R-04-001
Agency January 2004
<>EPA Research and
Development
Measurement of Fugitive Emissions at
a Region I Landfill
Prepared for
U.S. Environmental Protection Agency Region I
Prepared by
National Risk Management
Research Laboratory
Research Triangle Park, NC 27711
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EPA-600/R-04-001
January 2004
Measurement of Fugitive Emissions
at a Region I Landfill
by
Mark Modrak, Ram Hashmonay, and Robert Keagan
ARCADIS Geraghty & Miller
P.O. Box13109
Research Triangle Park, NC 27709
Contract No. 68-C99-201, Work Assignment No. 4-003
EPA Project Officer: Susan A. Thorneloe
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
Research Triangle Park, NC 27711
Prepared for:
U.S. Environmental Protection Agency
Office of Research and Development
Washington, DC 20460
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Abstract
This report discusses a new measurement technology for characterizing emissions from large
area sources. This work was funded by EPA's Monitoring and Measurement for the 21st Century
Initiative, or 21M2. The site selected for demonstrating this technology is a superfund landfill
that is being evaluated for recreational use. Data on methane and air toxics were needed to help
determine any increased risk to those using the site. Open-path Fourier transform infrared (OP-
FTIR) spectrometers were used to provide data on both background and surface emissions. The
technology provides concentration maps indicating the spatial variability and areas where
additional control may be needed. Horizontal scans to identify any hot spots and vertical scans
to determine the mass flux using a multiple-beam configuration were conducted. Optical remote
sensing-radial plume mapping provided concentration mapping of the site. These data will be
used to make decisions about potential recreational use of this site.
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Foreword
The U.S. Environmental Protection Agency (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, 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 EPA's Office of Research and Development to
assist the user community and to link researchers with their clients.
Lee A. Mulkey, Acting Director
National Risk Management Research Laboratory
in
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EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental Protection
Agency and approved for publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Information Service,
Springfield, Virginia 22161.
IV
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Contents
Section Page
Abstract ii
Foreword iii
EPA Review Notice iv
List of Figures vii
List of Tables viii
Executive Summary E-l
El. Background/Site Information E-l
El.l Horizontal Radial Plume Mapping E-2
El.2 Vertical Radial Plume Mapping E-2
E2. Results and Discussions E-2
E2.1 Horizontal Radial Plume Mapping Results E-2
E2.2 Vertical Radial Plume Mapping Results E-3
E2.3 Hazardous Air Pollutants E-4
E3. Concluding Statements E-4
1.0 Introduction 1-1
1.1 Background 1-1
1.2 Project Purpose and Description 1-2
1.2.1 Horizontal Radial Plume Mapping 1-4
1.2.2 Vertical Radial Plume Mapping 1-5
1.3 Data Quality Objectives and Criteria 1-6
1.4 Schedule of Work Performed for Project 1-8
2.0 The Measurements 2-1
2.1 Area A 2-1
2.2 Area B 2-3
2.3 Area C 2-4
2.4 Area D 2-5
2.5 Area E 2-5
2.6 Vertical Scanning 2-7
2.7 Meteorological Data 2-7
v
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Contents (continued)
Section Page
2.8 Data Analysis 2-8
3.0 Analytical Results and Discussion 3-1
3.1 The Horizontal RPM Results 3-1
3.2 The Vertical RPM Results 3-9
3.3 The Search for HAPs and Other Chemicals 3-12
4.0 Quality Assurance/Quality Control 4-1
4.1 Assessment of DQI Goals 4-1
4.2 Ethylene Tracer Release 4-2
4.3 Assessment of Number of Cycles Used for Moving Average 4-5
5.0 Conclusion 5-1
6.0 References 6-1
VI
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List of Figures
Figure Page
1-1 Map of the Somersworth Superfund Landfill 1-2
1-2 Overhead View of an Example Horizontal RPM Configuration 1-4
1-3 Example of a Vertical RPM Configuration 1-5
2-1 Schematic of OP-FTIR RPM Measurement Configuration in Area A 2-2
2-2 Schematic of OP-FTIR RPM Measurement Configuration in Area B 2-3
2-3 Schematic of OP-FTIR RPM Measurement Configuration in Area C 2-4
2-4 Schematic of OP-FTIR RPM Measurement Configuration in Area D 2-5
2-5 Schematic of OP-FTIR RPM Measurement Configuration in Area E 2-6
3-1 Reconstructed Methane Concentrations (in ppmv) for Area A 3-3
3-2 Reconstructed Methane Concentrations (in ppmv) for Area B 3-4
3-3 Reconstructed Methane Concentrations (in ppmv) for Area C 3-5
3-4 Reconstructed Methane Concentrations (in ppmv) for Area D 3-6
3-5 Reconstructed Methane Concentrations (in ppmv) for Area E 3-7
3-6 The OP-FTIR RPM Methane Concentration Contours Overlaid on the
Map of the Somersworth Superfund Landfill 3-8
3-7 Vertical Scan RPM Measurement of the Vertical Methane Plume Profile 3-10
3-8 Vertical Scan RPM Measurement of the Plume Profile from the Hot Spot
in the Valley 3-11
3-9 Two Beam RPM Measurement of the Vertical Methane Plume Profile on
the Western (Upwind) Side of the Landfill 3-12
4-1 OP-FTIR RPM Measurement of the Vertical Ethylene Tracer Plume Profile
on the Western (Upwind) Side of the Landfill 4-3
4-2 Time Series of the Calculated Ethylene Flux from Tracer Release Experiment .... 4-5
4-3 Calculated Average Methane Flux and Average CCF from the Vertical
Scanning Survey 4-6
vn
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List of Tables
Table Page
El. Range of Mean Methane Concentrations (in ppmv above global background)
Found in Each Survey Area E-3
1-1 DQI Goals for Critical Measurements 1-6
1-2 Detection Limits for Target Compounds 1-7
1-3 Schedule of Work Performed for Somersworth, NH Field Study 1-9
2-1 Coordinates of Mirrors Used for Horizontal Scanning in Area A 2-2
2-2 Coordinates of Mirrors Used for Horizontal Scanning in Area B 2-3
2-3 Coordinates of Mirrors Used for Horizontal Scanning in Area C 2-4
2-4 Coordinates of Mirrors Used for Horizontal Scanning in Area D 2-6
2-5 Coordinates of Mirrors Used for Horizontal Scanning in Area E 2-7
2-6 Coordinates of Mirrors Used for Vertical Scanning 2-7
3-1 Moving Average of Calculated Methane Flux, CCF, Wind Speed, and
Wind Direction for the Vertical Scanning Survey 3-2
3-2 Mean Methane Concentration (ppm) Determinations for Each Area 3-7
Vlll
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Executive Summary
E1. Background/Site Information
A field study was performed during September and October, 2002 by ARCADIS and the U.S.
EPA to measure emissions from a superfund site in Somersworth, New Hampshire using an
open-path Fourier transform infrared (OP-FTIR) spectrometer. The study involved a technique,
developed through research funded by the EPA's National Risk Management Research
Laboratory (NRMRL), which uses optical remote sensing-radial plume mapping (ORS-RPM)
to evaluate fugitive emissions.
The focus of the study was to characterize the emissions of methane and hazardous air pollutants
to assess landfill gas emissions from the site. The results will help determine whether active
controls will be required at the site. Concentrations of each compound were measured, and fluxes
(determined as the rate of flow per unit time, through a unit area) were calculated for each
compound detected. The site was divided into five survey areas for the field campaign. Detailed
maps of each survey area, and the survey configurations used in each area are included in the
report (see Figures 1-1,2-1 through 2-5, and Tables 2-1 through 2-5).
The ORS-RPM techniques used in the present study were designed to characterize the emissions
of fugitive gases from area sources. Detailed spatial information is obtained from path-integrated
ORS measurements by the use of optimization algorithms. The method involved the use of an
innovative configuration of non-overlapping radial beam geometry to map the concentration
distributions in a plane. This method, radial plume mapping (RPM) (Hashmonay et al., 1999; Wu
et al., 1999; Hashmonay et al., 2002), can also be applied to a vertical plane downwind from an
area emission source to map the crosswind and vertical profiles of a plume. By incorporating
wind information, the flux through the plane is calculated, which leads to an emission rate of the
upwind area source.
E-l
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E1.1 Horizontal Radial Plume Mapping
Horizontal scanning was performed in each of the five survey areas (see Figure 1-1) to search
for emission hot spots. Area A is located in the northwestern section of the landfill site; Area B
is located in the southeastern section of the site and includes a baseball field and basketball
courts; Area C is located in the northern section of the site and includes a baseball field; Area
D is located inside the chain-link fence of four tennis courts in the northeastern corner of the site;
Area E is located in the southwestern section of the site.
E1.2 Vertical Radial Plume Mapping
The vertical scan configuration was set up along the eastern boundary of the landfill site. This
location was chosen because it was optimum for determining a flux that would be representative
of the entire site under the given wind conditions. Figure 1-1 shows the location of the vertical
scanning configuration (the red line shows the location of the vertical plane, the red dot shows
the location of the OP-FTIR instrument, and the red square shows the location of the scissors
jack).
E2. Results and Discussions
An emissions contour map of the entire site and identification of three emission hot spots was
obtained from radial plume mapping. Vertical scanning enabled an estimate of the methane flux
from the entire site to be made.
E2.1 Horizontal Radial Plume Mapping Results
Horizontal scans were performed at each of the five survey areas. Figures 3-1 through 3-5 show
the average reconstructed methane concentrations in parts per million by volume for Areas A,
B, C, D, and E, respectively. The global methane background value of 1.75 ppm was subtracted
from each of the measurements taken. Table El shows a range of the area-averaged methane
concentrations measured in the five areas.
E-2
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Table E1. Range of Mean Methane Concentrations (in ppmv above global background) Found
in Each Survey Area.
Area
A
B
C
D
E
Range of Methane Concentrations
0.00 to 2.69
0.56 to 1.83
0.00 to 3. 06
0.00 to 1.91
0.00 to 1.44
The measured surface methane concentrations ranged from the global background to 3.06 ppm.
The average methane concentration found was 1.03 ppm above global background.
Figure 3-6 shows the horizontal RPM-determined methane concentration contours overlaid on
a map of the Somersworth site. The determination of this concentration map is based solely on
the mean path-integrated measurements made in each survey area, and six auxiliary path-
integrated measurements made by an additional OP-FTIR instrument. Figure 3-6 shows three
methane hot spots, one in Area A (2.5 ppm above ambient), the second in the northwest corner
of Area C (3.0 ppm above ambient), and the third hot spot, the most intense at 6.5 ppm above
ambient, occurred in a small valley that lies north of the baseball field in Area B. This hot spot
was identified in sub-area B, so the additional OP-FTIR instrument was set up in the valley and
made six auxiliary measurements. These six measurements provided the detail showing the sharp
concentration gradients shown in Figure 3-6. Strong methane emissions were located near an
uncapped vent that was on the south slope of the valley adjacent to Area B.
E2.2 Vertical Radial Plume Mapping Results
Vertical scanning was done on the eastern boundary of the landfill to determine a methane flux
from the entire site, which was estimated to be 5.8 g/s. Additionally, the methane flux from the
hot spots (found during the surface scanning survey) was estimated by modifying the vertical
scanning configuration slightly. The estimated methane flux from the hot spots was 3.3 g/s,
which represents 57 percent of the emission from the entire landfill.
E-3
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E2.3 Hazardous Air Pollutants
All data collected at the site, including data from horizontal and vertical scanning surveys, were
analyzed for any chemicals that are normally not found in the atmosphere, and this analysis did
not detect the presence of any of these chemicals at the site. This result is not surprising when
one notes that the maximum methane concentration measured at the landfill was 6.5 ppm, and
the minor constituents (neglecting aliphatic hydrocarbons) occur in landfills at levels that are
typically much less than 10"4 times the methane levels. Thus, minor constituents of the landfill
gases would be expected to be present at levels much lower than the detection limits of the OP-
FTIR instrument.
E3. Concluding Statements
The present study employed OP-FTIR sensors to determine chemical concentrations over the
entire area of the Superfund landfill in Somersworth, New Hampshire. The spatial information
was extracted from path-integrated OP-FTIR measurements using the RPM method. This
measurement-based technique provided a complete methane concentration-contour map of the
entire landfill and located methane emission hot spots (up to 6.5 ppm average above the global
background). In addition, the vertical scanning technique provided an estimate for the methane
emission from the entire landfill of 5.8 g/s. The methane emission rate from the hot spots in the
valley was determined to be 3.3 g/s, which is estimated to be 57 percent of the emission from the
entire landfill.
E-4
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1.0
Introduction
1.1 Background
A superfund site in Somersworth, New Hampshire is being considered for re-use as a soccer
field/recreational area, and the state has requested a study to assess landfill gas emissions from
this site. The results will help determine whether active controls will be required. The focus of
the study was to characterize the emissions of methane and hazardous air pollutants. The study
employed optical remote sensing (ORS) techniques to determine chemical concentrations over
the entire area of the landfill. These techniques result in the generation of maps showing the
locations of high methane concentrations. In addition, concentration contour lines (isopleths)
were generated in the downwind vertical plane from which emission rates were determined.
There is much concern over the potential hazards of landfill gas emissions. Hazardous air
pollutants (HAPs) at sufficient levels can result in negative health effects due to both short-term
and long-term exposures. The predominant component of landfill emissions is methane, which
can result in fire and possible explosions at high levels. Methane is also a major greenhouse gas
that is implicated in global warming. Adding to these concerns is the annoyance of the odors due
to some of the minor components of landfill gases. EPA has promulgated regulations under the
Clean Air Act to address the public health and welfare concerns of landfill gas emissions. The
final rule and guidelines are contained in 40 CFR Parts 51, 52, and 60, Standards of Performance
for New Stationary Sources and Guidelines for Control of Existing Sources: Municipal Solid
Waste Landfills.
The Somersworth site was divided into five rectangular survey areas (A-E). Figure 1-1 presents
the overall layout of the Somersworth Superfund Site, detailing the geographic location of each
survey region. Additionally, the figure shows the location of the vertical scanning configuration,
which was used to gather data in order to calculate emission fluxes for the entire site.
1-1
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^ / /
Figure 1-1. Map of the Somersworth Superfund Landfill
1.2 Project Purpose and Description
The optical remote sensing (ORS) techniques used in the present study were designed to
characterize the emissions of fugitive gases from area sources. These techniques were developed
in research and development programs funded by the U.S. EPA's National Risk Management
Research Laboratory (NRMRL). Detailed spatial information is obtained from path-integrated
ORS measurements by the use of optimization algorithms. The method involved the use of an
innovative configuration of non-overlapping radial beam geometry to map the concentration
distributions in a plane. This method, radial plume mapping (RPM) (Hashmonay et al., 1999; Wu
et al., 1999; Hashmonay et al., 2002), can also be applied to a vertical plane downwind from an
area emission source to map the crosswind and vertical profiles of a plume. By incorporating
wind information, the flux through the plane is calculated, which leads to an emission rate of the
upwind area source. An open-path Fourier transform infrared (OP-FTIR) sensor manufactured
1-2
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by Unisearch Associates was chosen for the present study because of its capability of accurately
measuring a large number of chemical species that might occur in a plume.
The OP-FTIR spectrometer combined with the RPM method can be used for both fence-line
monitoring applications, and real-time, on-site, remediation monitoring and source character-
ization. An infrared light beam modulated by a Michelson interferometer is transmitted from a
single OP-FTIR instrument to a corner cube mirror target, which is usually set up at a range of
100 to 500 meters. The returned light signal is received by the single telescope and directed to
a detector. The light is absorbed by the molecules in the beam path as the light is transmitted to
the mirror and again as the light is reflected back to the analyzer. Thus, the round-trip path of the
light doubles the chemical absorption signal. The OP-FTIR measures the path-integrated con-
centration (PIC) along the beam path. One advantage of OP-FTIR monitoring is that the con-
centrations of a multitude of infrared absorbing gaseous chemicals can be detected and measured
simultaneously with high temporal resolution.
The chemical vapor emitted from an emission source forms a plume, which is carried by the
wind across the multiple infrared beams. The OP-FTIR PIC measurements can be used with
wind data to calculate the emission rate applying the RPM method for vertical planes. The beam
measurements avoid the uncertainties that are inherent in the traditional point measurements.
Meteorological and survey measurements were also made. A theodolite was used to make the
survey measurement of the azimuth and elevation angles and the radial distances to the mirrors
relative to the OP-FTIR sensor. ARCADIS had the following tasks:
Collect OP-FTIR data in order to identify major emissions hot spots by generating
surface concentration maps in the horizontal plane
• Measure emission fluxes of detectable compounds downwind from major hot spots
Collect any ancillary data
• Demonstrate the operation and function of the ORS technology
Additionally, U.S. EPA personnel operated abistatic, non-scanning OP-FTIR (manufactured by
Midac) to determine ambient background concentrations, and these measurements were used to
correct the results of the ORS-RPM measurements for background contributions of the analytes.
The following sections provide general descriptions of the experiments performed at the site.
1-3
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1.2.1 Horizontal Radial Plume Mapping
The RPM approach provides spatial information to path-integrated measurements by optical
remote sensing. This technique yields information on the two-dimensional distribution of the
concentrations in the form of chemical-concentration contour maps (Hashmonay et al., 1999; Wu
et al., 1999; Hashmonay et al., 2002). This form of output readily identifies chemical "hot spots,"
the location of high emissions. This method can be of great benefit for performing site surveys
prior to site remediation activities.
Horizontal radial scanning is usually performed with the ORS beams located as close to the
ground as practical. This enhances the ability to detect minor constituents emitted from the
ground, since the emitted plumes dilute significantly at higher levels above the ground. The
survey area is divided into a Cartesian grid of n times m rectangular cells. A mirror is located in
each of these cells and the OP-FTIR sensor scans to each of these mirrors, dwelling on each for
a set measurement time (30 seconds in the present study). The system scans to the mirrors in the
order of either increasing or decreasing
azimuth angle. The path-integrated Dislocation Distance = 2.4 m; CCF = 1.0
concentrations measured at each mirror
are averaged over a several scanning
cycles to produce time-averaged
concentration maps. Meteoro-logical
measurements are made concurrent with
the scanning measurements.
Figure 1-2 represents a typical horizontal
RPM configuration in which n = m = 3.
The lines represent the nine optical paths,
each terminating at a mirror (Hashmonay
et al., 2002). The solid square represents a
point source. The enclosed areas represent
the calculated plume, transported down-
wind by the wind. The numbers associated
with the isopleths are the determined
values for the concentrations. Horizontal
scanning was performed at the five survey
areas depicted in Figure 1-1.
10 20
X Distance [m]
Figure 1-2. Overhead View of an Example Horizontal
RPM Configuration.
1-4
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1.2.2 Vertical Radial Plume Mapping
The vertical RPM method maps the concentrations in the vertical plane of the measurement. By
scanning in a vertical plane downwind from an area source, one can obtain plume concentration
profiles and calculate the plane-integrated concentrations. The flux is calculated by multiplying
the plane-integrated concentration by the wind speed component perpendicular to the vertical
plane. The flux leads directly to a determination of the emission rate (Hashmonay et al., 1998;
Hashmonay and Yost, 1999, Hashmonay et al., 2001). Thus, vertical scanning leads to a direct
measurement-based determination of the upwind source emission rate. At the Somersworth
Superfund Site, a vertical scanning measurement was performed at the eastern boundary (See
Figure 1-1).
Figure 1-3 shows a schematic of
the experimental setup used for
vertical scanning. Several mirrors
are placed in various locations on
a vertical plane in-line with the
scanning OP FTIR. Two of the
mirrors used in the configuration
are mounted on a scissors jack
(which is a piece of equipment
used to create a vertical platform
for mounting mirrors in the
configuration). The location of
the vertical plane is selected so
that it intersects the mean wind
direction as close to perpen-
dicular as practical. Vertical scan-
ning was performed on the down-
wind side of the Somersworth
Superfund site (the eastern border
in Figure 1-1), in order to esti-
mate a methane flux for the entire
site.
• Scanning
OP-FTIR
Figure 1-3. Example of a Vertical RPM Configuration
1-5
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1.3 Data Quality Objectives and Criteria
Data quality objectives (DQOs) are qualitative and quantitative statements developed using
EPA's DQO Process (described in EPA QA/G-4, Guidance for the Data Quality Objectives
Process) that clarify study objectives, define the appropriate type of data, and specify tolerable
levels of potential decision errors that will be used as the basis for establishing the quality and
quantity of data needed to support decisions. DQOs define the performance criteria that limit the
probabilities of making decision errors by considering the purpose of collecting the data, defining
the appropriate type of data needed, and specifying tolerable probabilities of making decision
errors. For this proj ect, the qualitative data quality obj ective is to provide data to support the state
in a risk assessment decision regarding this site.
Quantitative obj ectives are established for critical measurements using the data quality indicators
of accuracy, precision, and completeness. The acceptance criteria for these data quality indicators
are summarized in Table 1 -1. Accuracy of measurement parameters is determined by comparing
a measured value to a known standard. Values must be within the listed tolerance to be
considered acceptable. Accuracy can also be measured by calculating the percent bias of a
measured value to that of a true value.
Precision is evaluated by making replicate measurements of the same parameter and then
assessing the variations of the results. Replicate measurements are expected to fall within the
tolerances shown in Table 1 -1. Completeness is expressed as a percentage of the number of valid
measurements compared to the total number of measurements taken.
Table 1-1. DQI Goals for Critical Measurements
Measurement
Parameter
Wind direction
Wind speed
Optical path length
Mid-IR absorbance
Sampling
Method(s)
N/A
N/A
N/A
N/A
Analysis Method
Magnetic compass with
vane
Heavy duty wind cup set
Theodolite
FTIR
Accuracy
±5° tolerance
±0.8 m/s
±1 m
±10%
Precision
±5°
±0.8 m/s
±1 m
±10%abs
% Complete
90%
90%
100%
90%
1-6
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ORS-RPM was used at each test site to evaluate fugitive emissions of the target compounds, if
detectable. Estimated minimum detection limits, by compound, are given in Table 1-2. It is
important to note that the values listed in Table 1-2 should be considered first step approx-
imations, as the minimum detection limit is highly variable, and depends on many factors
including atmospheric conditions. Actual minimum detection levels are calculated in the
quantification software for all measurements taken. Minimum detection levels for each
absorbance spectrum are determined by calculating the root mean square (RMS) absorbance
noise in the spectral region of the target absorption feature. The minimum detection level is the
absorbance signal (of the target compound) that is five times the RMS noise level using a
reference spectrum acquired for a known concentration of the target compound.
Table 1-2. Detection Limits for Target Compounds
Compound
Acetaldehyde
Acetone
Acrylonitrile
Benzene
Bromodichloromethane
1,3-Butadiene
Butane
Carbon disulfide
Carbon tetrachloride
Carbonyl sulfide
Chlorobenzene
Chloroform
Chloromethane
1,4-Dichlorobenzene
Dichlorodifluoromethane
t-1 ,2-Dichloroethene
Dichlorofluoromethane
Dimethyl sulfide
Ethane
Ethanol
Sampling/ Analytical
Method
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
Estimated Detection Limits
for 100 m One-Way Path,
1 min Average (ppmv)
0.010
0.024
0.010
0.040
N/A
0.012
0.006
0.028
0.008
0.006
0.040
0.012
0.012
0.012
0.004
N/A
N/A
0.018
0.010
0.006
(Continued)
1-7
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Table 1-2. Detection Limits for Target Compounds (continued)
Compound
Ethyl benzene
Ethyl chloride
Ethyl mercaptan
Ethylene dibromide
Ethylene dichloride
Fluorotrichloromethane
Formaldehyde
Hexane
Hydrogen sulfide
Methane
Methyl chloroform
Methyl ethyl ketone
Methyl isobutyl ketone
Methyl mercaptan
Methylene chloride
Pentane
Propane
2-Propanol
Propylene dichloride
Tetrachloroethene
Toluene
Trichlorethylene
Vinyl chloride
Vinylidene chloride
Xylenes
Sampling/ Analytical
Method
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
FTIR
Estimated Detection Limits
for 100 m One-Way Path,
1 min Average (ppmv
0.060
0.004
N/A
0.006
0.030
0.004
0.006
0.006
6.0
0.024
0.006
0.030
0.040
0.060
0.014
0.008
0.008
0.006
0.014
0.004
0.040
0.004
0.010
0.014
0.030
1.4 Schedule of Work Performed for Project
One field measurement campaign was completed for this proj ect. The field tests were performed
at the site during the end of September and beginning of October 2002 and were completed in
six days (three days at the site and three days traveling to and from the site). Table 1-3 provides
the schedule of work that was performed for each day of the project.
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Table 1-3. Schedule of Work Performed for Somersworth, NH Field Study
Date
29 September 2002
30 September 2002
1 October 2002
2 October 2002
3 October 2002
4 October 2002
Day of Week
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Detail of Work Performed
Transport equipment to site
AM: Arrive at site
PM: Horizontal scanning of Area A (1 .5 hours)
Horizontal scanning of Area B (2 hours), Area D (2
hours), and Area E (1 hour)
Horizontal scanning of Area B (2 hours) and vertical
scanning
Transport equipment from site
Continue travel with equipment
1-9
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2.0
The Measurements
The following subsections describe testing procedures done at each of the five survey areas,
which are designated as Area A through Area E. Each site was scanned horizontally to produce
concentration maps and to locate any hot spots. In addition, a vertical scanning survey was done
on the eastern side of the site. In each of these sections, a figure is included that details the
respective survey area. The location of the vertical scanning configuration is depicted in Figure
1-1. The square shows the location of the scissors jack, the dot shows the location of the
scanner/OP-FTIR instrument, and the dashed line indicates the position of the vertical plane.
2.1 Area A
Area A is located in the northwestern section of the landfill site. A line of large trees bounds the
survey area on the northern side (see Figure 1-1). Figure 2-1 shows a schematic of the horizontal
scanning configuration in Area A, which was divided into nine cells located as in Figure 2-1. The
scanning OP-FTIR sensor was setup in the southeast corner of Cell 1 in Area A. In the RPM
calculations, the boundaries of Cells 8 and 9 were altered to accommodate the tree-lined fence.
Table 2-1 lists the radial coordinates (relative to the OP-FTIR sensor) for each of the nine
mirrors.
2-1
-------
180
160
140
120
100
80
60
40
20
0
-40 -20 0 20 40 60 80 100 120 140
Figure 2-1. Schematic of OP-FTIR RPM Measurement
Configuration in Area A (distances in meters).
Table 2-1. Coordinates of Mirrors Used for Horizontal Scanning in Area A.
Mirror Number
1
2
3
4
5
6
7
8
9
Radial Distance3
(m)
58.9
64.1
103
121
130
125
191
179
170
Azimuth Angle from North3
(deg)
315
334
2
304
320
332
296
307
313
The radial distance and azimuth are relative to the position of the scanning
OP-FTIR.
2-2
-------
2.2 Area B
Area B is located in the southeastern section of
the site, includes a baseball field and basketball
courts (see Figure 1-1), and is divided into 11
cells. Figure 2-2 is a schematic of the horizontal
scanning configuration in Area B and shows the
scanning OP-FTIR sensor was setup in the
northwest corner of the area. A second
monostatic (Unisearch) OP-FTIR system was
setup four meters from the scanning OP-FTIR
and made simultaneous measurements over two
paths to the mirror positions shown in Figure 2-2
for Cells 10 and 11. These measurements were
combined with those made to the nine cells by
the scanning system, resulting in an eleven-cell
RPM computation. Table 2-2 lists the radial
coordinates (relative to the OP-FTIR sensor) for
each of the nine mirrors.
200
150
100
50
-4
FTIR-2
*
-10
r
/ .-•
i ..-
i -•' /
i1-/
/ /'f
;i / j
I//
N^*f&?
7
/
/
(-'
/
.---''
/ /
/ a--"'
/ / ,:*
/"
/ 5 -'
---'^
•
/ 11
/ /•
/*
•
' 6
_-.
3
7
0 -20 0 20 40 60 80 100 120
Figure 2-2. Schematic of OP-FTIR RPM Meas-
urement Configuration in Area B
(distances in meters).
Table 2-2. Coordinates of Mirrors Used for Horizontal Scanning in Area B.
Mirror Number
1
2
3
4
5
6
7
8
9
10
11
Radial Distance3
(m)
51.4
63.4
89.8
90.4
105
114
128
139
149
219
219
Azimuth Angle from North3
(deg)
119
147
156
100
117
132
93
104
116
97
119
The radial distance and azimuth are relative to the position of the scanning
OP-FTIR.
2-3
-------
2.3 Area C
Area C is located in the northern section of the site and includes a baseball field (see Figure 1-1).
Figure 2-3 is a schematic of the horizontal scanning configuration in Area C and shows the
scanning OP-FTIR sensor set up in the southeastern corner of the area. A fence cut across the
northwest corner of the area, resulting in locating some of the mirrors in less than optimum po-
sitions for the RPM algorithm. The radial coordinates are given for all nine mirrors in Table 2-3.
140 r
120
100
80
BO
40
20
-60
-40
-20
40
80
100
120
Figure 2-3. Schematic of OP-FTIR RPM Measurement Configuration
in Area C (distances in meters).
Table 2-3. Coordinates of Mirrors Used for Horizontal Scanning in Area C.
Mirror Number
1
2
3
4
5
6
7
8
9
Radial Distance3
(m)
38.1
50.1
99.6
80.5
76.4
90.5
123
122
131
Azimuth Angle from North3
(deg)
301
347
358
270
297
321
265
281
295
The radial distance and azimuth are relative to the position of the scanning
OP-FTIR.
2-4
-------
2.4 Area D
Area D is inside the chain-link fence of four tennis courts in the northeastern corner of the
landfill site (see Figure 1-1). Figure 2-4 is a schematic of the horizontal scanning configuration
in Area D and shows the setup in this area was different from the other areas in that the scanning
OP-FTIR sensor was located on the center of one side, instead of a corner, of the rectangular
area. The scanning sensor was located on the western side of Area D. Since Area D was confined
by a chain-link fence, it was much smaller than the other survey areas in the study. The
coordinates of the nine mirrors are listed in Table 2-4.
70
60
50
40
30
20
10
-10
-20
20
40
60
80
100
Figure 2-4. Schematic of OP-FTIR RPM Measurement Configuration in
Area D (distances in meters).
2.5 Area E
Area E is located in the southwestern section of the site (see Figure 1-1). Figure 2-5 shows a
schematic of the horizontal scanning configuration in Area E. The scanning OP-FTIR sensor was
setup in the northeastern corner of the designated area, and only four mirrors were used. The
coordinates of the four mirrors are listed in Table 2-5.
2-5
-------
Table 2-4. Coordinates of Mirrors Used for Horizontal Scanning in Area D.
Mirror Number
1
2
3
4
5
6
7
8
9
Radial Distance3
(m)
41.6
27.6
32.8
50.8
43.7
46.1
70.9
60.2
64.3
Azimuth Angle from North3
(deg)
35
73
121
55
80
104
54
83
107
The radial distance and azimuth are relative to the position of the scanning
OP-FTIR.
100
80
60
40
20
-20
-40 L-
-20
20
40
60
80
100
120
140
160
Figure 2-5. Schematic of OP-FTIR RPM Measurement Configuration in Area E
(distances in meters).
2-6
-------
Table 2-5. Coordinates of Mirrors Used for Horizontal Scanning in Area E.
Mirror Number
1
2
3
4
Radial Distance3
(m)
55.3
123
85.5
126
Azimuth Angle from North3
(deg)
253
275
215
259
The radial distance and azimuth are relative to the position of the scanning
OP-FTIR.
2.6 Vertical Scanning
The vertical scan configuration was set up along the eastern boundary of the landfill site. This
location was chosen because it was optimum under the given wind condition for determining a
methane flux that would be representative of the entire site. Figure 1-1 shows the location of the
vertical scanning configuration (the line shows the location of the vertical plane, the dot shows
the location of the scanner/OP-FTIR, and the square shows the location of the scissors] ack). The
angular coordinates of the five mirrors are listed in Table 2-6.
Table 2-6. Coordinates of Mirrors Used for Vertical Scanning.
Mirror Number
1
2
3
4
5
Radial Distance3
(m)
47.1
109
110
111
186
Elevation Angle"
(deg)
0
0
2
6
0
Azimuth Angle from North3
(deg)
6
1
2
1
2
a The radial distance and azimuth are relative to the position of the scanning OP-FTIR.
b Elevation angle shown is the angle from the horizontal axis to the mirror.
2.7 Meteorological Data
Meteorological data, including wind direction, wind speed, temperature, relative humidity, and
barometric pressure, were continuously collected during the sampling campaign with a
2-7
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Climatronics weather station, model 101990-G1. The weather station collects real-time data from
its sensors and records time-stamped data to a data logger.
Wind direction and speed-sensing heads were used to measure the wind speed and direction at
height of 2 and 10 meters. The sensing heads for wind direction incorporate an automatic sensing
function that adjusts to true north, eliminating the errors associated with using a compass
heading. The sensing heads incorporate standard cup-type wind speed sensors.
2.8 Data Analysis
The OP-FTIR data were collected as interferograms and archived to CD-ROMs. The archived
interferograms were delivered to U. S. EPA personnel, who performed the conversions to absorb-
ance spectra, which they analyzed to determine concentrations using Non-Lin (Spectrosoft)
software. This analysis was done after completion of the field campaign. The concentration
determinations were combined with the appropriate mirror locations, wind speed, and wind
direction, and algorithms developed in MatLab (Math-works) were then used to process the data
into horizontal plane concentration maps or vertical plane plume profiles. The fluxes were then
determined as the product of the determined area-integrated concentrations times the component
of the wind speed normal to the vertical measurement plane.
Copies of the interferogram data were also analyzed by ARCADIS. These spectra files were
searched for volatile organic compounds (VOCs) and ammonia concentrations, and EPA's
methane-concentration determinations were verified.
2-8
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3.0
Analytical Results and Discussion
The RPM algorithm is the tool that extracts the spatial information from the open-path
measurements to produce plume concentration maps and emission rates. The concordance
correlation factor (CCF) is used to represent the level of fit for the reconstruction in the path-
integrated domain (predicted vs. observed PIC) (Hashmonay et. al, 1999). The CCF is similar
to the Pearson correlation coefficient but is adjusted to account for shifts in location and scale.
Like the Pearson correlation, CCF values are bounded between -1 and 1, yet the CCF can never
exceed the absolute value of the Pearson correlation factor. For example, the CCF will be equal
to the Pearson correlation when the linear regression line intercepts the ordinate at 0, its slope
equals 1, and its absolute value will be lower than the Pearson correlation when these conditions
are not met. For the purposes of this report, the closer the CCF value is to 1, the better the fit for
the reconstruction in the path-integrated domain.
In reporting the average calculated fluxes, a moving average is used in Table 3-1 to show
temporal variability in the flux values. A moving average involves averaging flux values
calculated from several different consecutive cycles (a cycle is defined as data collected when
scanning one time through all the mirrors in the configuration). For example, a data set taken
from five cycles may be reported using a moving average of four, where values from cycle one
to four and two to five are averaged together to show any variability in the flux values.
3.1 The Horizontal RPM Results
Figures 3-1 through 3-5 present the average reconstructed methane concentrations for Areas A
through E, respectively. The contours give methane concentrations in ppmv, and the Xs show
the positions of the mirrors. The corresponding schematic diagrams of each area provide
directional indicators. Additionally, the calculated CCF for each reconstruction is provided.
Table 3-2 shows a list of the area-averaged concentrations of methane in all of the 42 cells
measured in the 5 areas. The table also includes five auxiliary measurements taken with the
Unisearch OP-FTIR within Cell 10 of Area B. These additional measurements were taken to
3-1
-------
provide more detailed spatial information on the hot spot detected in this area. The listed
methane values are area averages for each of the cells as computed by the RPM algorithms. The
global methane background value of 1.75 ppm was subtracted from each of the area-averaged
values. The highest methane area-averaged concentrations were measured in Cell 8 (3.06 ppm)
in Area C and Cells 1 and 2 in Area A (2.64 ppm and 2.69 ppm, respectively, see Figures 2-1 and
2-3). The methane levels in these three cells were more than 2.5 ppm higher than the global
background level of 1.75 ppm. The area-averaged determinations for methane in the other 39
cells ranged from the ambient background level to 2.27 ppm above background. The mean value
of all 42 determinates was 1.03 ppm.
Table 3-1. Moving Average of Calculated Methane Flux, CCF, Wind Speed, and Wind
Direction for the Vertical Scanning Survey.
Cycles
1 to 4
2 to 5
3 to 6
4 to 7
5 to 8
6 to 9
7 to 10
8 to 11
9 to 12
10 to 13
11 to 14
Average
St. Dev. of Mean
CCF
0.999
0.998
0.998
0.993
0.992
0.985
0.985
0.994
0.994
0.997
0.999
0.994
0.0051
Flux
(g/s)
4.4
5.2
5.5
5.1
6.0
6.5
7.1
8.7
7.7
6.4
5.1
6.1
1.28
Wind Speed
(mis)
2.23
2.32
2.27
2.42
2.78
2.73
2.78
2.72
2.41
2.29
2.11
-
-
Wind Direction3
(deg)
7
3
0
0
1
3
1
356
345
340
333
-
-
Wind direction shown is the angle from a vector normal to the plane of the configuration.
3-2
-------
180
160
140
120
100
80
60
40
20
0 20 40 60 80 100
x
Figure 3-1. Reconstructed Methane Concentrations (in ppmv) for Area A (distances in
meters).
3-3
-------
120
100
80
60
40
20
0
0
20
40 60
x
80
Figure 3-2. Reconstructed Methane Concentrations (in ppmv) for Area B (distances in meters).
3-4
-------
120
100*
80
60
40
20
-20 0 20 40 60 80 100
Figure 3-3. Reconstructed Methane Concentrations (in ppmv) for Area C
(distances in meters).
3-5
-------
60
50
40
30
20
10
0 10 20 30 40 50 60 70
Figure 3-4. Reconstructed Methane Concentrations (in ppmv) for Area D (distances
in meters).
3-6
-------
80
70
60
50
40
30
20
10
X
X
20
40
60
80
100
120
Figure 3-5. Reconstructed Methane Concentrations (in ppmv) for Area E (distances
in meters).
Table 3-2. Mean Methane Concentration (ppm) Determinations for Each Area.
Cell
Number
1
2
3
4
5
6
7
8
9
10
11
Area A
2.6
2.7
1.2
0.00
0.00
0.00
0.62
0.33
0.00
Area B
1.3
0.65
1.3
1.6
0.56
0.75
1.8
0.68
0.92
1.1
0.31
Area B Auxiliary
Measurements
1.5
0.00
1.7
6.4
5.8
AreaC
1.6
0.95
0.77
2.3
1.4
0.79
0.00
3.1
0.00
Area D
1.1
1.3
1.3
0.72
0.85
1.8
1.9
1.5
1.3
Area E
1.1
0.15
1.4
0.00
3-7
-------
Figure 3-6 shows RPM-determined methane concentration contours overlaid on a site map of
the Somersworth landfill. The dots indicate the OP-FTIR locations used to collect the data. The
determination of this concentration map is based solely on the mean path-integrated measure-
ments in the five areas comprising a total of 42 cells and 5 auxiliary path-integrated measure-
ments made by the Unisearch OP-FTIR in Area B. The methane concentration map shows three
hot spots, one in Area A (2.5 ppm above ambient), the second in the north west corner of Area
C (3.0 ppm above ambient), and the third hot spot, the most intense at 6.5 ppm above ambient,
occurred in the small valley north of the baseball field in Area B. Since this hot spot was
identified in Area B, the Unisearch OP-FTIR was setup in the valley and made path-integrated
measure-ments to five mirror positions in, and on, the north and south slopes of the valley.
Including the five path-integrated measurements from the Unisearch instrument in the RPM
calculation of provided the detail showing the sharp concentration gradients shown in Figure 3 -6.
The Unisearch measurements located strong methane emissions from an uncapped vent
(probably from a hole dug for a utility pole that was never installed) located on the south slope
of the valley adjacent to the Area B ball field.
Figure 3-6. The OP-FTIR RPM Methane Concentration Contours Overlaid on the Map of the
Somersworth Superfund Landfill.
3-8
-------
3.2 The Vertical RPM Results
Table3-l presents methane emission flux determinations from the vertical scanning survey. See
Figure 1-1 for the location of the vertical scanning survey at the site. The first column of this
table refers to a running average calculation from the several cycles. The second column shows
the calculated CCF. The third, fourth, and fifth columns show the calculated methane flux, the
average wind speed, and the wind direction, respectively, during the time the measurements were
taken.
Figure 1 -3 shows the schematic of the vertical scanning configuration. The measurement was set
up on the eastern boundary that was on the downwind side of the landfill and located so that the
centerline of the methane plume emitted from the hot spots in the valley and from Areas C and
A would intersect the beam paths. The centerline of the plume was closer to the mirror tower
than to the OP-FTIR sensor, and some of the plume extended beyond the tower. This portion of
the plume was captured by the beam to mirror number 5, which was situated 186 meters from
the sensor.
The emission flux was determined for the vertical-plane area shown in Figure 3-7 (186 meters
horizontal and 23 meters vertical) by multiplying the area-integrated concentration by the
component of the wind speed normal to the vertical plane. This resulted in a flux value of 5.8
g/sec. This vertical plane captured most of the methane plume emitted from the landfill; thus,
the flux through this plane is approximately equal to the emission rate for the entire landfill.
The vertical scanning configuration shown in Figure 3-7 was situated just downwind of the
location of high methane emissions in the valley, which is referred to as the hot spot. However,
the vertical plane with the 186-meter horizontal distance extended sixty meters beyond the hot-
spot plume. The vertical scan measurements can also be used to determine the emission flux
from the hot spot by narrowing the RPM computation to the portion of the vertical plane through
which the hot spot plume passes, as shown in Figure 3-8. The RPM determined flux for this
modified plane, which extends to 140 meters from the OP-FTIR sensor, was 4.6 g/sec. This flux
also includes contributions from the areas of the landfill that are upwind of the hot spot. To
determine the net flux from the hot spot, a vertical plane configuration was set up immediately
upwind, just west of the hot spot and collected data simultaneously. This configuration, which
used two separate non-scanning OP-FTIR sensors, is shown in Figure 3-9. The flux through this
plane was determined as 1.3 g/sec. The net flux through the 140-meter by 25-meter plane is the
difference between the flux through the downwind plane and that of the upwind plane, 3.3 g/sec.
3-9
-------
Since the downwind plane contained the hot-spot plume, the mean emission rate from the hot
spot is estimated to be 3.3 g/sec, which represents 57 percent of the emission (5.8 g/sec) from
the entire landfill.
22
20
18
Concentrations are in ppm
Flux = 5.8 g/s
40
60 80 100 120 140
Crosswind Distance [meters]
160
180
Figure 3-7. Vertical Scan RPM Measurement of the Vertical Methane Plume Profile (numbers
on the isopleths are methane concentrations above the global background).
3-10
-------
Concentrations are in ppm
Flux = 4.6 g/s
40
60 80
Crosswind Distance [meters]
100
120
Figure 3-8. Vertical Scan RPM Measurement of the Plume Profile from the Hot Spot in the
Valley (numbers on the isopleths are methane concentrations above the global
background).
3-11
-------
22
20
18
16
•i- 12
lio
Concentrations are in ppm
Flux=1.3g/s
40
60 80 100
Crosswind Distance [meters]
120
140
Figure 3-9. Two Beam RPM Measurement of the Vertical Methane Plume Profile on the
Western (Upwind) Side of the Landfill (numbers on the isopleths are the
methane concentrations above the global background).
3.3 The Search for HAPs and Other Chemicals
All regions of the spectra collected by both MID AC and Unisearch Open-Path FTIRs were
carefully searched for absorption features due to any chemicals that are normally not in the
atmosphere. This search included all measurements on the 42 beams and from the vertical
measurements as well as the Unisearch measurements near the methane hot spot in the valley.
No absorption features were found. This result is not surprising, when one notes that the
maximum concentration of methane measured at the landfill was 6.5 ppm. The minor
constituents (neglecting the aliphatic hydrocarbons) occur at landfills at levels that are typically
much less than 10"4 times the methane levels. Thus we would expect the minor constituents of
the landfill gases to be lower than 650 pptv in the ground-level atmosphere, which are levels
considerably lower than the detection limits of the OP-FTIR systems.
3-12
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4.0
Quality Assurance/Quality Control
In preparation for this project, a Category III Quality Assurance Project Plan (QAPP) was
prepared and approved prior to the field campaign. In addition, standard operating procedures
were in place during the survey.
4.1 Assessment of DQI Goals
The data quality obj ectives established for critical measurements using the data quality indicators
(DQIs) of accuracy, precision, and completeness are listed in Table 1-1 of this document.
However, the goal is to develop improved DQIs for the applied techniques used in this type of
research project.
Although calibration of the Climatronics heads did not occur prior to the field study, both
Climatronics heads were calibrated in March 2003 by the U. S. EPA/APPCD Metrology Lab (the
previous calibration of both heads was in November 1999). All functions were checked during
the March 2003 calibration, and the only adjustment made was an approximately 4° change to
wind direction for one of the Climatronics heads. As shown in Table 1-1, accuracy within 5%
is an acceptable range, and this variance will have very little bearing on the final flux estimate.
It should also be noted that the wind direction measurement is not as critical to the flux estimates
as the wind speed measurement. Additionally, checks for agreement of the wind speed and wind
direction measured from the two heads (2m and 10m) were done. While it is true that some
variability in the parameters measured at both levels should be expected, this is a good first-step
check for assessing the performance of the instruments.
It has been determined that the accuracy of the measured optical path-lengths (which are
collected using the theodolite), as stated in the QAPP and by the manufacturer's specifications,
are not crucial to our method. However, calibration of the theodolite was done in the field during
May 2003. The optical path-length was checked by measuring a standard distance of 50 feet
4-1
-------
(15.24 meters). The same distance was measured twice using the theodolite and yielded distances
of 15.43 and 15.39meters. These results fall well within the acceptable accuracy range stated in
Table 1 -1. The horizontal angle was checked by setting up two targets approximately 180° apart,
measuring the two horizontal angles between the targets, and calculating the sum, which should
be 360°. These angles were measured twice using the theodolite. The first test yielded a sum of
359°21'18", and the second test yielded a sum of 359°59'55". Both of these values fall well
within the acceptable accuracy range stated in Table 1-1.
As a QC check of the accuracy of the OP_FTIR, we have verified the measurement of the known
atmospheric background nitrous oxide concentration of around 320 ppbv from data taken with
the monostatic OP-FTIR. It should be noted that 320 ppbv is an average value, as the
atmospheric background value exhibits a slight seasonal variation. The data were taken from a
sample of the actual data collected during the current field campaign. The average nitrous oxide
concentration found was 337 ± 9.121 ppbv. This value falls within the accuracy goals stated in
Table 1-1.
Additionally, DQI procedures for proper operation, as described in EPA Compendium method
TO-16, and the OP-FTIR EPA Guidance Document were followed for this study. The develop-
ment of DQI standards for this method is a future goal, and improved DQI standards will be
included in future QAPP documents written using this method.
4.2 Ethylene Tracer Release
To verify the accuracy of the method used to calculate emission flux, a tracer gas was released
during the vertical scanning survey. Ethylene was released through a soaker hose configuration
located directly west of the vertical scanning survey. The wind direction during the time of the
release was almost due west, which allowed the vertical configuration to capture the plume from
the tracer release. The soaker hoses were set up in an "H" configuration to simulate an area
source, and the approximate dimensions of the "H" configuration were 10 meters wide and 40
meters long on each side. Using a digital scale, the weight of the ethylene cylinder was recorded
prior to release of the gas and immediately after the release was completed. In addition, the
precise starting and ending time of the release was recorded in order to calculate the average
actual flux of ethylene. This flux value was then compared to the ethylene flux calculated from
the vertical scanning survey.
4-2
-------
Figure 4-1 shows a schematic of the vertical scanning configuration used to simultaneously
measure the methane emissions and the ethylene tracer plume. The configuration is overlaid by
the ethylene plume profile in the form of concentration contours as determined by the RPM
algorithm. The emission flux through the vertical measurement plane, calculated from the area
integration of the concentration profile multiplied by the component of the wind speed normal
to the vertical plane, was determined as 0.98 g/sec. Since the measurement plane captured the
entire plume, the entire flux through the plane is the emission rate of ethylene.
12
10
"
g>
I 6
RPM Determination = 0.98 g/s
Actual Rate = 1.01 g/s
\ m n
20 40 60 80 100 120
Crosswind Distance [meters]
140
160
180
Figure 4-1. OP-FTIR RPM Measurement of the Vertical Ethylene Tracer Plume Profile on the
Western (Upwind) Side of the Landfill. These Determinations Were Made from the
Same OP-FTIR Measurements as the Methane Vertical Plume Profile (numbers on
the isopleths are the ethylene concentrations in ppm).
4-3
-------
Ethylene tracer gas was released for 75 minutes. During this period, the measured mass of the
ethylene cylinder was reduced by 4.59 kg. A loss of 4.59 kg over a 75-minute period indicates
an average flow rate of 1.02 g/sec. The measured emission rate indicates an ethylene mass
recovery of 96%.
The flux of the ethylene release determined by mass-loss agrees well with the average ethylene
flux calculated from the vertical scanning survey. Observed wind directions during the vertical
scanning survey were not highly variable, which is indicative of a stable atmosphere. Hashmonay
et al. [2001] found that fluxes calculated during stable environments underestimated the actual
flux by around 12%. The average ethylene flux calculated during the current experiment
underestimated the actual average ethylene flux by 3.9%.
The favorable results found were due to the orientation of the prevailing winds, with respect to
the vertical configuration. Table 3-2 shows that the observed wind direction was generally
perpendicular to the vertical configuration during the entire survey. This allowed the config-
uration to capture a large amount of the ethylene plume from the site. Another factor that
contributed to the favorable results found was the small variability in wind direction and speed
during the period of the survey, which indicates very stable atmospheric conditions. Flux calcu-
lations in unstable atmospheric conditions tend to underestimate down to 60% of the actual
fluxes (Hashmonay et al., 2001).
Figure 4-2 shows a time series of the calculated ethylene fluxes measured during the tracer
release study. It is apparent that the calculated flux decreases sharply with time. This was
expected, as the ethylene flow rate was decreased rapidly after the experiment began in order to
prevent the regulator on the cylinder from freezing. It is important to note that, despite the
fluctuation in the actual flow rate of the ethylene release, the experiment still yielded very
favorable results.
4-4
-------
Calculated Ethylene Flux from Tracer Release
1.6
1.4
1.2
3 0.8
S 0.6
LJ_
0.4
0.2
4 6
Cycle Number
8
10
Figure 4-2. Time Series of the Calculated Ethylene Flux from Tracer Release Experiment
4.3 Assessment of Number of Cycles Used for Moving Average
A statistical analysis of the methane fluxes (measured from the vertical scanning configuration)
was done to investigate trends in methane concentrations, standard deviations, and the average
CCF when a different number of cycles is used for the moving average. The statistical analysis
suggests that a moving average of four cycles is sufficient to provide a valid emission flux.
Figure 4-3 shows the average methane flux and average CCF calculated using many different
numbers of cycles for the moving average. The figure shows that the average calculated methane
flux increases slightly as the number of cycles used for the moving average increases but begins
to level off after two cycles. Additionally, the figure shows that the standard deviations of
methane fluxes decreases after two cycles. The CCF plot shows a similar trend, with values
leveling off after four cycles, and standard deviations decreasing as well.
4-5
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Calculated Average Methane Flux and Average CCF
097
Figure 4-3. Calculated Average Methane Flux and Average CCF from the Vertical
Scanning Survey
4-6
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5.0
Conclusion
The present study employed Open-path FTIR sensors to determine chemical concentrations over
the entire area of the Superfund landfill in Somersworth, New Hampshire. The spatial
information was extracted from the path-integrated open-path FTIR measurements using the
RPM method. This measurement-based technique provided a complete methane concentration-
contour map of the entire landfill and located areas of high methane emissions (up to 6.5 ppm
average methane concentration above the global background). In addition, the vertical scanning
technique provided an estimate for the methane emission of 5.8 g/sec from the entire landfill.
The methane emission rate from the hot spots in the valley was determined to be 3.3 g/sec, which
is 57 percent of the emission from the entire landfill. The vertical scanning technique was tested
for accuracy by using ethylene tracer release. The RPM determination of the ethylene emission
rate agreed with the actual release rate to within four percent.
5-1
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6.0
References
Hashmonay, R.A., K. Wagoner, D.F. Natschke, D.B. Harris, and E.L. Thompson, Radial
Computed Tomography of Air Contaminants Using Optical Remote Sensing, presented at the
AWMA 95th Annual Conference and Exhibition, Baltimore, MD, June 23-27, 2002.
Hashmonay, R.A., D.F. Natschke, K. Wagoner, D.B. Harris, E.L. Thompson, and M.G. Yost,
Field Evaluation of a Method for Estimating Gaseous Fluxes from Area Sources Using Open-
Path Fourier Transform Infrared, Environ. Sci. Technol., 35, 2309-2313, 2001.
Hashmonay, R. A., and M.G. Yost, Innovative Approach for Estimating Fugitive Gaseous Fluxes
Using Computed Tomography and Remote Optical Sensing Techniques, J. Air Waste Manage.
Assoc., 49, 966-972, 1999.
Hashmonay, R.A., M.G. Yost, D.B. Harris, and E.L. Thompson, Simulation Study for Gaseous
Fluxes from an Area Source Using Computed Tomography and Optical Remote Sensing,
presented at SPIE Conference on Environmental Monitoring and Remediation Technologies,
Boston, MA, Nov., 1998, in SPIE Vol. 3534, 405-410.
Hashmonay, R. A., M.G. Yost, and Chang-Fu Wu, Computed Tomography of Air Pollutants
Using Radial Scanning Path-Integrated Optical Remote Sensing, Atmospheric Environment, 33
(2), 267-274, 1999.
Wu, C-F., M.G. Yost, R. A., Hashmonay, D. Y. Park, Experimental Evaluation of a Radial Beam
Geometry for Mapping Air Pollutants Using Optical Remote Sensing and Computed
Tomography, Atmospheric Environment, 33 (28), 4709-4716, 1999.
Tsai, M.Y., M.G. Yost, C.F. Wu, R.A. Hashmonay, and T.V. Larson, Line Profile
Reconstruction: Validation and Comparison of Reconstruction Methods, Atmospheric
Environment, 35 (28), 4791-4799, 2001.
6-1
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Measurement of Fugitive Emissions at a Region I Landfill
5. REPORT DATE
January 2004
6. PERFORMING ORGANIZATION CODE
7. AUTHORS
M. Modrak, R. Hashmonay, and R. Keagan
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
ARCADIS Geraghty & Miller
P.O. Box13109
Research Triangle Park, NC 27709
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-C99-201, WA 4-003
12. SPONSORING AGENCY NAME AND ADDRESS
U. S. EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final: 01/01/02 to 08/19/03
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES
The EPA Project Officer is Susan A. Thorneloe, mail drop E305-02, phone (919) 541-2709
16. ABSTRACT
The report discusses a new measurement technology for characterizing emissions from large area
sources. The work was funded by EPA's Monitoring and Measurement for the 21st Century Initiative, or
21M2. The site selected for demonstrating this technology is a superfund landfill that is being evaluated for
recreational use. Data on methane and air toxics were needed to help determine any increased risk to
those using the site. Open-path Fourier transform infrared (OP-FTIR) spectrometers were used to provide
data on both background and surface emissions. The technology provides concentration maps indicating
the spatial variability and areas where additional control may be needed. Horizontal scans to identify any
hot spots and vertical scans using a multiple-beam configuration to determine the mass flux were
conducted. Optical remote sensing-radial plume mapping provided concentration mapping of the site.
These data will be used to make decisions about potential recreational use of this site.
17.
KEYWORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Aerosol Particles
Earth Fills (Landfill)
Organic Compounds
Methane
Pollution Control
Stationary Sources
14G
13C
17C
7C
18. DISTRIBUTION STATEMENT
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
52
Release to Public
20. SECURITY CLASS (This Page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77 ) PREVIOUS EDITION IS OBSOLETE
6-2
forms/admin/techrpt.frm 7/8/99 pad
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