United States
Environmental Protection
Agency
HEPA Project Summary D
Measurement of Fugitive
Emissions at a Region I Landfill
Mark Modrak, Ram Hashmonay, and Robert Keagan
The report discusses a field study to
measure methane and hazardous air
pollutant emissions from a superfund
site in Somersworth, NH. The results
will help determine whether active con-
trols will be required at the site. Con-
centrations of each compound were
measured, and fluxes (determined as
the rate of flow per unit time through a
unit area) were calculated for each com-
pound detected. The study used an
open-path Fourier transform infrared
spectrometer and optical remote sens-
ing-radial plume mapping. Measured
surface methane concentrations ranged
from 0 to 3.06 ppm above the global
background methane concentration of
1.75 ppm, and hot spots with methane
emissions up to 6.5 ppm average above
the global background were located. The
methane flux from the entire site was
estimated to be 5.8 g/s. No hazardous
air pollutants were detected.
This Project Summary was developed
by the National Risk Management Re-
search Laboratory's Air Pollution Pre-
vention and Control Division, Research
Triangle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Background
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, NH using an open-path
Fourier transform infrared (OP-FTIR) spec-
trometer. The study involved a technique,
developed through research funded by
the EPA's National Risk Management
Research Laboratory (NRMRL), that uses
optical remote sensing-radial plume map-
ping (ORS-RPM) to evaluate fugitive emis-
sions.
The focus of the study was to charac-
terize the emissions of methane and haz-
ardous air pollutants to assess landfill
gas emissions from the site. The results
will help determine whether active con-
trols will be required at the site. Concen-
trations 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.
Site Information
The 26-acre Somersworth Sanitary
Landfill, shown in Figure 1, is located in a
predominantly residential area approxi-
mately 1 mile southwest of downtown
Somersworth. Forest Glade Park, which
was reclaimed as a recreational park in
1978, sits atop the easternmost 10 acres
of the site. An apartment building for se-
nior citizens, a fire station, and a National
Guard Armory abut the property to the
east, and an elementary school is located
approximately 2,300 feet northeast.
The Somersworth site was divided into
five rectangular survey subareas (A-E).
Figure 1 presents the overall layout of the
Somersworth Superfund Site, detailing the
geographic location of each survey re-
gion. Additionally, the figure shows the
location of the vertical scanning configu-
ration, which was used to gather data in
order to calculate emission fluxes for the
entire site.
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Jfc*
Figure 1. Map of the Somersworth Superfund Landfill showing the survey subareas.
Measurements
The ORS-RPM techniques used in the
present study were designed to charac-
terize the emissions of fugitive gases from
area sources. Detailed spatial informa-
tion is obtained from path-integrated ORS
measurements by the use of optimization
algorithms. The method involves the use
of an innovative configuration of non-over-
lapping radial beam geometry to map the
concentration distributions in a plane. This
RPM method 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 incor-
porating wind information, the flux through
the plane is calculated, which leads to an
emission rate of the upwind area source.
Surface RPM
Surface scanning was performed in
each of the five survey subareas shown
in Figure 1 to search for emission hot
spots. Area A is located in the northwest-
ern 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; and
Area E is located in the southwestern
section of the site.
Vertical Scanning
Vertical scanning was done to deter-
mine the emission flux for each compound
detected. 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 condi-
tions. Figure 1 shows the location of the
vertical scanning configuration. The
dashed line shows the location of the
vertical plane, the large dot shows the
location of the OP-FTIR instrument, and
the large square shows the location of
the scissors jack.
Results
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 en-
tire site to be made.
Surface RPM Results
Table 1 shows a range of the area-
averaged methane concentrations in the
five subareas. The measured surface
methane concentrations ranged from 0 to
3.06 ppm above the global background
methane concentration of 1.75 ppm. The
average methane concentration was 1.03
ppm above global background.
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Figure 2.OP-FTIR RPM methane concentration contours overlaid on the map of the Somersworth Superfund Landfill.
Table I.DRange of mean methane concentra-
tions above global background found
in each survey subarea.
Area
A
B
C
D
E
Methane Concentration
Range, ppm
0.00 to
0.56 to
0.00 to
0.00 to
0.00 to
2.69
1.83
3.06
1.91
1.44
Figure 2 shows the 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-inte-
grated measurements made in each sur-
vey sub-area and on six auxiliary
path-integrated measurements made by
an additional OP-FTIR instrument. Figure
2 shows methane hot spots in Area A
(2.5 ppm above ambient), in the north-
west corner of Area C (3.0 ppm above
ambient), and in a small valley that lies
north of the baseball field in Area B (6.5
ppm above ambient, the most intense).
The Area B hot spot was identified in
sub-area B, so an additional OP-FTIR
instrument was set up in the valley and
made six auxiliary measurements. Includ-
ing these six measurements provided the
detail showing the sharp concentration
gradients shown in Figure 2. Strong meth-
ane emissions were located near an un-
capped vent on the south slope of the
valley adjacent to Area B.
Vertical Scanning Results
Vertical scanning was done on the east-
ern boundary of the landfill to determine
a methane flux from the entire site, which
was estimated to be 5.8 g/s. The meth-
ane flux from the hot spots found during
the surface scanning survey was esti-
mated to be 3.3 g/s, which represents
57% of the entire landfill emission.
Hazardous Air Pollutants
All data collected at the site (including
data from surface and vertical scanning
surveys) were analyzed for any chemi-
cals that are not normally found in the
atmosphere, and the analysis did not de-
tect any of these chemicals at the site.
This result is not surprising considering
that the maximum methane concentration
measured at the landfill was 6.5 ppm.
The minor constituents (neglecting ali-
phatic hydrocarbons) occur in landfills at
levels that are typically much less than
1CH times the methane levels. Thus, the
minor constituents of the landfill gases
would be expected to be present at lev-
els much lower than the detection limits
of the OP-FTIR instrument.
Conclusions
The study employed OP-FTIR sensors
to determine chemical concentrations
over the entire area of the Superfund land-
fill in Somersworth, NH. The spatial infor-
mation was extracted from path-integrated
OP-FTIR measurements using the RPM
method. A complete methane concentra-
tion contour map of the entire landfill was
developed from these measurements, and
methane emission hot spots (up to 6.5
ppm average above the global back-
ground) were located. In addition, the ver-
tical 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% of the emission
from the entire landfill.
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M. Modrak, R. Hashmonay, and R. Keagan are with ARCADIS Geraghty & Miller,
Research Triangle Park, NC 27709.
Susan A. Thorneloe is the EPA Project Officer (see below).
The complete report, entitled "Measurement of Fugitive Emissions at a Region I
Landfill," is available at http://www.epa.gov/appcdwww/apb/EPA-600-R-04-
001.pdf or as Order No. PB2004-103034; Cost $31.50, subject to change
from:
National Technical Information Serviceo
5285 Port Royal Roado
Springfield, VA 22161-00010
Telephone: (703) 605-60000
(800) 553-6847 (U.S. only)
The EPA Project Officer can be contacted at:
Air Pollution Prevention and Control Division
National Risk Management Research Laboratory
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711-00010
United States
Environmental Protection Agency
CenterforEnvironmental Research Information
Cincinnati, OH 45268
PRESORTED STANDARD
POSTAGES FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use
$300
EPA/600/SR-04/001
March 2004
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