EPA-600/R-05/041

April 2005

Evaluation of Fugitive

Emissions at a Former

Landfill Site in Colorado

Springs, Colorado Using

Ground-Based Optical

Remote Sensing

Technology
EPA-600/R-05/041

April 2005

Evaluation of Fugitive Emissions at a

Former Landfill Site in Colorado

Springs, Colorado Using

Ground-Based Optical Remote

Sensing Technology

by

Mark Modrak

Ram A. Hashmonay

Ravi Varma

Robert Kagann

ARCADIS G&M, Inc

4915 Prospectus Dr. Suite F,

Durham, NC 27713

Contract Number: EP-C-04-023

Work Assignment Number: 0-25

Project Officer: Susan A. Thorneloe

National Risk Management Laboratory

Air Pollution Prevention and Control Division

Research Triangle Park, NC 27711

U.S. Environmental Protection Agency

Office of Research and Development

Washington, DC 20460
ii

Abstract

A former landfill site located in Colorado Springs, Colorado was assessed for landfill gas

emissions in support of reuse options for the property. The current owners of the landfill and

the State of Colorado requested assistance from the EPA Region 8 Office, and the Office of

Superfund Remediation and Technology Innovation, Technology Integration and Information

Branch to perform a site assessment to search for the presence of any fugitive gas emissions

from the site.

The focus of this study was to evaluate fugitive emissions of methane and volatile organic

compounds at the site in support of the reuse objectives, using a scanning open-path Fourier

transform infrared spectrometer, open-path tunable diode laser absorption spectroscopy, and

an ultra-violet differential optical absorption spectrometer. The study involved a technique

developed through research funded by the EPA’s National Risk Management Research

Laboratory that uses ground-based optical remote sensing technology, known as optical remote

sensing-radial plume mapping. The horizontal radial plume mapping (HRPM) method was used

to map surface concentrations, and the Vertical Radial Plume Mapping (VRPM) method was

used to measure emissions fluxes downwind of the site.

The HRPM surveys detected the presence of a methane hot spot in the Northeast quadrant of

the site, and the peak concentration for this hot spot was greater than 0.4 ppm above ambient

background levels. Another methane hot spot was detected in the Southeast quadrant of the site,

and the peak concentration for this hot spot was greater than 0.5 ppm above ambient

background. The VRPM survey measured an average methane flux from the site of 4.9 g/s. The

location of the peak of the reconstructed methane plume agrees well with the location of the hot

spots detected during the HRPM surveys. This suggests that emissions from the two hot spots

are a major source of the methane plume detected during the VRPM survey.
iii

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.

Sally Gutierrez, Acting Director

National Risk Management Research Laboratory
iv

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.
v

Contents

Section Page

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x

1 Project Description and Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.2 Project Description and Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.2.1 Horizontal RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

1.2.2 Vertical RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

1.3 Quality Objectives and Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

1.4 Project Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

2 Testing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.1 HRPM Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

2.1.1 Northwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

2.1.2 Southwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.1.3 Northeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.1.4 Southeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.2 VRPM Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.3 OP-TDLAS Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

3 Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.1 The Horizontal RPM Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2 The Vertical RPM Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.3 VOC and Ammonia Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.4 OP-TDLAS Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

4 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

5 QA/QC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.1 Equipment Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.2 Assessment of DQI Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.2.1 DQI Check for Analyte PIC Measurement . . . . . . . . . . . . . . . . . . . . . . 5-1

5.2.2 DQI Checks for Ambient Wind Speed and Wind Direction

Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

5.2.3 DQI Check for Precision and Accuracy of Theodolite Measurements . 5-3

5.3 QC Checks of OP-FTIR Instrument Performance . . . . . . . . . . . . . . . . . . . . . . 5-3

5.4 Validation of Concentration Data Collected with the OP-FTIR . . . . . . . . . . . 5-4

5.5 Internal Audit of Data Input Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Contents (concluded)

Section Page

vi

5.6 OP-TDLAS Instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

6 List of References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Appendix A: OP-FTIR Mirror Coordinates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B: OP-TDLAS Configuration Path Length Distances . . . . . . . . . . . . . . . . . . B-1

Appendix C: Methane Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1
vii

List of Tables

Table Page

1-1 Summary Information on the ORS Instrumentation Used in the Study . . . . . . . . . 1-4

1-2 Detection Limits for Target Compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6

1-3 Schedule of Work Performed at the Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7

3-1 Moving Average of Calculated Methane Flux, CCF, Wind Speed, and Wind

Direction for the Downwind As-Built Area Upper Cell . . . . . . . . . . . . . . . . . . . . . 3-2

3-2 Minimum Detection Levels by Compound for the OP-FTIR Instrument . . . . . . . . 3-4

3-3 Average Methane Concentrations aove Ambient Background Levels

Measured with the OP TDLAS System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

5-1 Instrumentation Calibration Frequency and Description . . . . . . . . . . . . . . . . . . . . . 5-1

5-2 DQI Goals for Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

A-1 Distance and Horizontal Coordinates of Mirrors Used in the HRPM Survey of

Northwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A-2 Distance and Horizontal Coordinates of Mirrors Used in the HRPM Survey of 

Southwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A-3 Distance and Horizontal Coordinates of Mirrors Used in the HRPM Survey of

Northeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A-4 Distance and Horizontal Coordinates of Mirrors Used in the HRPM Survey of 

Southeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

A-5 Distance, and Horizontal and Vertical Coordinates of Mirrors Used in the VRPM 

Survey of Northern Border . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2

B-1 Distance of Path Lengths Used in OP-TDLAS Configurations . . . . . . . . . . . . . . B-1

C-1 Methane Concentrations Found during the HRPM Survey of the

Northeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

C-2 Methane Concentrations Found during the HRPM Survey of the

Northwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-2

C-3 Methane Concentrations Found during the HRPM Survey of the

Southeast Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-3

C-4 Methane Concentrations Found during the HRPM Survey of the

Southwest Quadrant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-4

C-5 Methane Concentrations Found during the VRPM Survey . . . . . . . . . . . . . . . . . C-5
viii

List of Figures

Figure Page

E-1 Map of the Site Detailing the Location of the HRPM Survey Areas . . . . . . . . . . . . xi

E-2 Map of the Site Detailing the Location of the VRPM Configurations . . . . . . . . . . . xi

1-1 Colorado Springs, Colorado, Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1-2 Map of Colorado Springs Site Showing the Location of the HRPM

Survey Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1-3 Map of the Colorado Springs Site Showing the Location of the VRPM

Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1-4 OP-FTIR Instrument/Scanner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1-5 Example of a HRPM Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

1-6 Example of a VRPM Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

2-1 Passive Vent Sealed During the HRPM Surveys . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2-2 Schematic of the HRPM Configuration Used in the NW Quadrant . . . . . . . . . . . . 2-2

2-3 Schematic of the HRPM Configuration Used in the SW Quadrant . . . . . . . . . . . . 2-3

2-4 Schematic of the HRPM Configuration Used in the NE Quadrant . . . . . . . . . . . . 2-3

2-5 Schematic of the HRPM Configuration Used in the SE Quadrant . . . . . . . . . . . . . 2-3

2-6 OP-TDLAS System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

2-7 Schematic of the OP-TDLAS Configuration Used on September 10 . . . . . . . . . . . 2-4

2-8 Schematic of OP-TDLAS Configuration Used on September 11 . . . . . . . . . . . . . 2-4

3-1 Average Surface Methane Concentration Contour Map of the Colorado

Springs Landfill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3-2 Average Reconstructed Methane Plume from the VRPM Survey . . . . . . . . . . . . . 3-3

3-3 Methane Flux and Prevailing Wind Direction Measured During the

VRPM Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

5-1 Comparison of a Spectrum Measured at the Site to Reference Spectra of

Gasoline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4

5-2 Post-Colorado Springs Comparison of Methane Concentrations Measured

with the OP-TDLAS and OP-FTIR Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . 5-5
ix

Acknowledgments

This study was jointly sponsored by the United States Environmental Protection Agency

(EPA) Region 8 Office, and the Office of Superfund Remediation and Technology

Innovation, Technology Integration and Information Branch under its Monitoring and

Measurement for the 21st Century (21M2) initiative. The 21M2 initiative is intended to

provide EPA staff with resources to apply new approaches to real site problems.
x

Executive Summary

Background and Site Information

A former landfill site located in Colorado Springs, Colorado was assessed for landfill gas

emissions in support of reuse options for the property. The landfill is approximately 40 acres,

and landfill operations took place on the site from about 1957 to 1980. The landfill accepted

waste from both commercial and residential operations. Several volatile organic compounds

(VOCs) are known to be present in soil gas and groundwater beneath the landfill. The current

landfill owners and the State of Colorado requested assistance from EPA to perform a site

assessment searching for the presence of any fugitive gas emissions from the site. This

assessment was necessary due to the potential adverse health effects associated with exposure

to landfill gas. The EPA Region 8 Office requested assistance with this study through the 21M2

program to utilize innovative approaches for performing an assessment at the site.

The focus of this study was to evaluate emissions of fugitive gases and VOCs at the site in

support of the reuse objectives, using an open-path Fourier transform infrared (OP-FTIR)

spectrometer and an open-path tunable diode laser absorption spectroscopy (OP-TDLAS)

system. The OP-FTIR instrument provided the critical measurements in the current study. The

OP-TDLAS provided non-critical, supplemental data. The study involved a technique

developed through research funded by the U.S. EPA’s National Risk Management Research

Laboratory (NRMRL) that uses ground-based optical remote sensing technology, known as

optical remote sensing-radial plume mapping (ORS-RPM) (Hashmonay and Yost, 1999;

Hashmonay et al., 1999; Wu et al., 1999; Hashmonay et al., 2001; Hashmonay et al., 2002).

The site assessment consisted of one field campaign performed during September 2003 by

ARCADIS and EPA personnel. Figure E1 presents the overall layout of the site, detailing the

geographic location of each horizontal radial plume mapping (HRPM) survey area. Figure E2

shows the location of the vertical radial plume mapping (VRPM) configuration that was used

to collect data for emission flux calculations.

Testing Procedures

HRPM surveys were done in the NW, SW, NE, and SE quadrants to search for surface

emissions of methane, ammonia, and VOCS (see Table 1 of the report for a list of target

compounds). A VRPM survey was done along the northern border of the site to measure

emissions of methane, ammonia, and VOCS downwind of the site. The OP-TDLAS instrument

was deployed along the surface of the site, and on a slope adjacent to the southern boundary of

the site to provide additional information on methane concentrations. 
xi

Figure E-2. Map of the Site Detailing the Location of the

VRPM Configurations.

Figure E-1. Map of the Site Detailing the Location of the HRPM

Survey Areas.
xii

Results and Discussion

HRPM Results

The HRPM surveys of the site detected the presence of a methane hot spot in the Northeast

quadrant of the site. The peak concentration for this hot spot was greater than 0.4 ppm above

the determined ambient background level of 1.55 ppm, which was the lowest methane

concentration measured during the field campaign. Another methane hot spot was detected in

the Southeast quadrant of the site. The peak concentration for this hot spot was greater than 0.5

ppm above ambient background.

VRPM Results

The VRPM survey measured an average methane flux from the site of 4.9 g/s. The location of

the peak of the reconstructed methane plume agrees well with the location of the hot spots

detected during the HRPM surveys. This suggests that emissions from the two hot spots are a

major source of the methane plume detected during the VRPM survey.

VOC and Ammonia Results

All data sets from the HRPM and VRPM surveys were searched for the presence of VOCs and

ammonia. The analysis detected the presence of gasoline (primarily octane) during the HRPM

survey of the Northeast quadrant. However, this is attributed to emissions from the gasoline

generators used in the field campaign, which were located upwind of the measurement

configuration during the HRPM survey of the Northeast quadrant. The measured gasoline

concentrations ranged from below the detection limit to 23 ppb. Analysis of the other data sets

did not detect VOCs or ammonia at levels higher than the minimum detection levels of the

OP-FTIR instruments.

OP-TDLAS Measurements

The OP-TDLAS survey of the surface of the site found average methane concentrations

between 0.47 and 0.53 ppm above the ambient background level of 1.55 ppm. The surface

methane concentrations measured with the OP-TDLAS system agree fairly well with the

methane levels measured during the HRPM surveys.

The survey of the slope along the southern boundary of the site found relatively higher methane

concentrations. The largest average methane concentration detected was 1.34 ppm above

ambient background. The relatively larger standard deviations found during the slope survey

suggest that methane hot spots were present along the slope.
1-1

Figure 1-1. Colorado Springs, Colorado, Site.

Chapter 1

Project Description and Objectives

1.1 Background

A former landfill site located in Colorado Springs,

Colorado was assessed for landfill gas emissions as

part of an effort to rehabilitate the site as a recreational facility. The landfill is approximately 40 acres

and accepted waste from both commercial and

residential sources from about 1957 to 1980. Several

volatile organic compounds (VOCs) are known to be

present in soil gas and groundwater beneath the

landfill. The current owners of the landfill and the

State of Colorado requested assistance from the EPA

to perform a site assessment to search for the presence of any fugitive gas emissions from the site. This

assessment was necessary due to the potential adverse health effects associated with exposure to

landfill gas. The EPA Region 8 Office requested

assistance with this study through the 21M2

 program

to utilize innovative approaches for performing an

assessment at the site. Figure 1-1 shows a picture of

the site.

The focus of this study was to evaluate emissions of

fugitive gases, such as methane and ammonia, and

VOCs at the site in support of the reuse objectives,

using an pen-path Fourier transform infrared (OPFTIR) spectrometer and an open-path tunable diode

laser absorption spectroscopy (OP-TDLAS) system.

The OP-FTIR instrument provided the critical measurements in the current study. The OP-TDLAS

system provided non-critical, supplemental data on

methane concentrations. The study involved a technique developed through research funded by the U.S.

EPA’s National Risk Management Research Laboratory NRMRL that uses ground-based optical remote

sensing technology, known as optical remote sensing-radial plume mapping (ORS-RPM) (Hashmonay

and Yost, 1999; Hashmonay et al., 1999; Wu et al.,

1999; Hashmonay et al., 2001; Hashmonay et al.,

2002). The assessment identified emission hot spots

(areas of relatively higher emissions), investigated

source homogeneity, and calculated an emission flux

rate for each compound detected at the site. This

information can be used to identify specific areas at

the site in need of better gas control and to assess

whether or not better controls should be implemented

at the site as a whole. Concentration maps in the

horizontal and downwind vertical planes were generated using the horizontal radial plume mapping

(HRPM), and vertical plume mapping (VRPM)

methods, respectively.

The study consisted of one field campaign performed

during September 2003 by ARCADIS and EPA

personnel. The Colorado Springs site was divided

into four areas. Figure 1-2 presents the overall layout

of the site, detailing the geographic location of the

HRPM survey areas. The red dot indicates the position of the OP-FTIR instrument during the HRPM

surveys. Figure 1-3 shows the location of the VRPM

configuration used at the site. The blue dot indicates
Evaluation of Fugitive Emissions at a

1-2

Figure 1-2. Map of Colorado Springs Site Showing the Location

of the HRPM Survey Areas.

Figure 1-3. Map of the Colorado Springs Site Showing the

Location of the VRPM Configuration.
Former Landfill in Colorado Springs, Colorado

1-3

Figure 1-4. OP-FTIR Instrument/Scanner.

the location of the OP-FTIR; the blue diamond

indicates the location of a scissors jack (vertical

structure) on which were placed three mirrors used in

the configuration; and the blue squares indicate the

location of the surface mirrors.

1.2 Project Description and Purpose

The objectives of the study were to identify major

emissions hot spots by collecting OP-FTIR data and

creating surface concentration maps in the horizontal

plane, measure emission fluxes of detectable compounds downwind from major hot spots, and demonstrate the operation and function of the optical remote

sensing (ORS) technologies.

The ORS techniques used in this study were designed

to characterize the emissions of fugitive gases from

area sources. Detailed spatial information is obtained

from path-integrated ORS measurements by iterative

algorithms. The HRPM method involves a configuration of non-overlapping radial beam geometry to map

the concentration distributions in a horizontal plane.

This 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 incorporating wind information, the flux through the plane

is calculated, which leads to an emission rate of the

upwind area source. An OP-FTIR sensor was chosen

as the primary instrument for the 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 ORSRPM method is designed for fence-line monitoring;

real-time, on-site hot spot detection and source

characterization; and emissions flux determination.

An infrared light beam modulated by a Michelson

interferometer is transmitted from a single telescope

to a retroreflector (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 it propagates to the mirror and

absorbed further as it is reflected back to the ana

lyzer. One advantage of OP-FTIR monitoring is that

the concentrations of a multitude of infrared absorbing gaseous chemicals can be detected and measured

simultaneously with high temporal resolution. Figure

1-4 shows a picture of the OP-FTIR instrument/

scanner used in the current study.

The OP-TDLAS system (Unisearch Associates) is a

fast, interference-free technique for making continuous concentration measurements of many gases. The

OP-TDLAS used in the current assessment is capable

of measuring concentrations in the range of tens of

parts per billion over an open path up to 1 km, for

gases such as carbon monoxide, carbo dioxide,

ammonia, and methane. The laser emits radiation at

a particular wavelength when an electrical current is

passed through it. The light wavelength depends on

the current and therefore allows scanning over an

absorption feature and analyzing for the target gas

concentration, using Beer’s law. The OP-TDLAS

used in this study is a multiple channel TDL instrument that allows fast scanning electronically (few

seconds) among many beam-paths (presently, 8

beams). The OP-TDLAS applies a small 4-inch

telescope, which launches the laser beam to a mirror.

The laser beam is returned by the mirror to the

telescope, which is connected with fiber optics to a

control box that houses the laser and a multiple

channel detection device. For this particular field

campaign, data from the OP-TDLAS were used to

provide additional information on methane concentrations at the site. At the time of the field campaign, the

OP-TDLAS system had only recently been acquired

by EPA. Consequently, standard operating and
Evaluation of Fugitive Emissions at a

1-4

Figure 1-5. Example of a HRPM Configuration.

calibration procedures were still being developed.

Table 1-1 presents summary information on the ORS

instrumentation used in this study. The table lists the

compounds measured by each instrument during the

current study, and instrument limitations such as

weather and interfering species.

Table 1-1. Summary Information on the ORS

Instrumentation Used in the Study

Parameter OP-FTIR OP_TDLAS

Wavelength range Infrared (2–20

μm)

Near Infrared

(-1.5 μm)

Target analysis

Methane, ammonia, gasoline,

other VOCs

Methane

Detection limit Parts per billion Parts per billion

Limiting weather

conditions

Heavy rain Heavy rain, fog

Interfering species carbon dioxide.

water

None

Meteorological and survey measurements were also

made during the field campaign. 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.

1.2.1 Horizontal RPM

The HRPM provides spatial information to pathintegrated measurements acquired in a horizontal

plane by an ORS system. This technique yields

information on the two-dimensional distribution of

the concentrations in the form of chemicalconcentration contour maps. This form of output

readily identifies the location of higher chemical

emissions, or “hot spots.” This method can be of

great benefit for performing site surveys before,

during, and after site remediation activities. In this

particular study, this method is useful for identifying

areas where the landfill gas collection control system

may not be functioning properly. These areas are the

major source of emissions from the site.

HRPM scanning is usually performed with the ORS

beams located as close to the ground as is practical.

This enhances the ability to detect minor constituents

emitted from the ground, since the emitted plumes

dilute significantly at higher elevations. 

The survey area is typically divided into a Cartesian

grid of n times m rectangular cells. In some unique

cases, the survey area may not be rectangular due to

obstructions, and the shape of the cells may be

slightly altered accordingly. A mirror is located in

each of these cells, and the ORS sensor scans to each

of these mirrors, dwelling on each for a set measurement time (30 seconds in the present assessment).

The system scans to the mirrors in the order of either

increasing or decreasing azimuth angle. The pathintegrated concentrations (PIC) measured at each

mirror are averaged over several scanning cycles to

produce time-averaged concentration maps. Meteorological measurements are made concurrent to the

scanning measurements.

Figure 1-5 represents a typical HRPM configuration.

In this particular case, n = m = 3. The solid lines

represent the nine optical paths, each terminating at

a mirror.
Former Landfill in Colorado Springs, Colorado

1-5

Figure 1-6. Example of a VRPM Configuration.

One OP-FTIR instrument (manufactured by Unisearch Associates) was used to collect HRPM data

during the field campaign.

1.2.2 Vertical RPM

The VRPM method maps the concentrations in the

vertical plane by scanning the ORS system in a

vertical plane downwind from an area source. One

can obtain the plane-integrated concentration from

the reconstructed concentration maps. The flux is

calculated by multiplying the plane-integrated concentration by the wind speed component perpendicular to the vertical plane. Thus, the VRPM method

leads to a direct measurement-based determination of

the upwind source emission rate (Hashmonay et al.,

1998; Hashmonay and Yost, 1999, Hashmonay et al.,

2001).

Figure 1-6 shows a schematic of the experimental

setup used for vertical scanning. Several mirrors were

placed in various locations on a vertical plane in-line

with the scanning OP-FTIR. A vertical platform

(scissors jack) was used to place two of the mirrors at

a predetermined height above the surface. The location of the vertical plane is selected so that it intersects the mean wind direction as close to perpendicular as practical. One OP-FTIR instrument (manufactured by IMACC, Inc.) was used to complete the

VRPM survey.

1.3 Quality Objectives and Criteria

Data quality objectives (DQOs) are qualitative and

quantitative statements developed using EPA’s DQO

Process (U.S. EPA QA/G-4, 2000) 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. 

Quantitative objectives are established for critical

measurements using the data quality indicators

(DQIs) of accuracy, precision, and completeness. The

acceptance criteria for these DQIs are summarized

later in Table 5-2 of Section 5 of this report. Accuracy of measurement parameters is determined by

comparing a measured value to a known standard,

assessed in terms of percent bias. Values must be

within the listed tolerance to be considered acceptable.

Precision is evaluated by making replicate measurements of the same parameter and assessing the

variations of the results. Precision is assessed in

terms of relative percent difference (RPD) or relative

standard deviation (RSD). Replicate measurements

are expected to fall within the tolerances shown later

in Table 5-2. Completeness is expressed as a percentage of the number of valid measurements compared

to the total number of measurements taken.

Estimated minimum detection limits of the OP-FTIR

instrument, 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 approximations, as the

minimum detection limit is highly variable and

depends on many factors including atmospheric

conditions. Actual minimum detection levels are
Evaluation of Fugitive Emissions at a

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Table 1-2. Detection Limits for Target Compounds.

Compound

OP-FTIR Estimated Detection

Limit for Path Length = 100m,

1 min Average

(ppmv)

AP-42 Value ratioed to an

average methane concentration of 50 ppma

(ppmv)

1,4-Dichlorobenzene 0.012 0.000021

2-Propanol 0.0060 0.0050

Acetone 0.024 0.00070

Acrylonitrile 0.010 0.00063

Butane 0.0060 0.00050

Chlorobenzene 0.040 0.000025

Chloroform 0.012 0.0000030

Chloromethane 0.012 0.00010

Dichlorodifluoromethane 0.0040 0.0016

Dimethyl sulfide 0.018 0.00078

Ethane 0.010 0.089

Ethanol 0.0060 0.0027

Ethyl benzene 0.060 0.00046

Ethyl chloride 0.0040 0.00013

Ethylene dibromide 0.0060 0.00000010

Ethylene dichloride 0.030 0.000041

Fluorotrichloromethane 0.0040 0.000076

Hexane 0.0060 0.00066

Hydrogen sulfide 6.0 0.0036

Methane 0.024 N/Ab

Methanol 0.0015 N/A

Methyl ethyl ketone 0.030 0.00071

Methyl isobutyl ketone 0.040 0.00019

Methyl mercaptan 0.060 0.00025

Methylene chloride 0.014 0.0014

Octane 0.0025 N/A

Pentane 0.0080 0.00033

Propane 0.0080 0.0011

Propylene dichloride 0.014 0.000018

Tetrachloroethene 0.0040 0.00037

Trichlorethylene 0.0040 0.00028

Vinyl chloride 0.010 0.00073

Vinylidene chloride 0.014 0.000020

Xylenes 0.030 0.0012

a The AP-42 values represent an average concentration of different pollutants in the raw landfill gas. This is not comparable

to the detection limits for the OP-FTIR which is an average value for a path length of 100 meters across the surface of the

area source being evaluated. However, it does provide an indication of the types of pollutants and range of concentrations

associated with landfill gas emissions in comparison to the detection limits of the OP-FTIR. b N/A = not available.
Former Landfill in Colorado Springs, Colorado

1-7

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.

1.4 Project Schedule

The field campaign was completed for this study

during September 2003. Table 1-3 provides the

schedule of ORS work that was performed.

Table 1-3. Schedule of Work Performed at the Site.

Day Detail of Work Performed

Tuesday, September 9 Travel to site

Wednesday, September 10 AM—HRPM survey of NW quadrant

PM—HRPM survey of SW quadrant

Thursday, September 11 AM—HRPM survey of NE quadrant

PM—HRPM survey of SE quadrant

Friday, September 12 VRPM survey of site

Saturday, September 13 Travel from site
Evaluation of Fugitive Emissions at a

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Former Landfill in Colorado Springs, Colorado

2-1

Figure 2-1. Passive Vent Sealed During the

HRPM Surveys.

Chapter 2

Testing Procedures

The following subsections describe the testing procedures used at the site. The site was divided into

quadrants designated as Northeast, Northwest,

Southeast, and Southwest. HRPM was performed in

each of the quadrants to produce surface concentration maps and to locate any emissions hot spots.

VRPM was performed on the northern border of the

site. The coordinates of the mirrors used in each

configuration relative to the position of the OP-FTIR

instrument are presented in Appendix A.

The site contained several passive vents located

approximately 2 m above the surface. These vents

were sealed during the HRPM surveys of the surface

(see Figure 2-1). The rational for sealing the vents

was that they were suspected emissions hot spots, and

may have masked other emissions hot spots located

along the surface of the site. The seals were removed

from the vents for the VRPM survey.

OP-FTIR data were collected as interferograms and

archived to CD-ROMs. After archiving, the interferograms were transferred to ARCADIS. They were then

transformed to absorbance spectra, and concentrations were calculated using Non-Lin (Spectrosoft)

quantification software. This analysis was done after

completion of the field campaign. Concentration data

were then matched with the appropriate mirror

locations, wind speed, and wind direction. The

ARCADIS RPM software was used to process the

data into horizontal plane concentration maps or

vertical plane plume visualizations, as appropriate.

Meteorological data including wind direction, wind

speed, temperature, relative humidity, and barometric

pressure were continuously collected during the

measurement campaign with a Climatronics model

101990-G1 instrument. The Climatronics instrument

is automated. It collects real-time data from its

sensors and records time-stamped one-minute averages to the data collection computer. Wind direction

and speed sensing heads were used to collect data at

the surface during the HRPM surveys and at heights

of 2 and 10 m during the VRPM survey (the 10 m
Evaluation of Fugitive Emissions at a

2-2

Figure 2-2. Schematic of the HRPM Configuration Used in the Northwest Quadrant.

sensor was placed on top of the scissors jack). The

sensing heads for wind direction incorporate an

auto-north function (automatically adjusts to magnetic north) that eliminates the errors associated with

subjective field alignment to a compass heading.

After collection, a linear interpolation between the

two sets of data is done to estimate wind velocity as

a function of height.

Once the concentrations maps and wind information

were processed, the concentration values were integrated, incorporating the wind speed component

normal to the plane at each height level to compute

the flux through the vertical plane. In this stage, the

concentration values were integrated from parts per

million by volume to grams per cubic meter, considering the molecular weight of the target gas and

ambient temperature. This enables the flux to be

calculated directly in grams per second using wind

speed data in meters per second.

The concordance correlation factor (CCF) is used to

measure the reproducibility of a reference measurement to another measurement. In the RPM methodologies, it is used to represent the level of fit for the

reconstruction in the path-integrated domain (predicted vs observed PIC). The CCF is similar to the

Pearson correlation coefficient (r) 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, and its slope equals 1. Its absolute

value will be lower than the Pearson correlation when

the above 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.

A moving average is used in the calculation of the

average flux values to show temporal variability in

the measurements. A moving average involves

averaging flux values calculated from several 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 5

cycles may be reported using a moving average of 4,

where values from cycles 1 to 4, and 2 to 5 are

averaged together to show any variability in the flux

values.

The shape of the plume maps generated by this method are used to give information on the homogeneity

of the plume and do not affect the calculated flux

values. The shape of the maps generated represents

the best fit of the limited data to a symmetric Gaussian function, and this fit may drive the plume shape

outside of the measurement configuration.

2.1 HRPM Measurements

The variation in terrain at the site resulted in a unique

geometry and measurement configuration for each

quadrant.

2.1.1 Northwest Quadrant

The Northwest quadrant was bounded on the north

and west side by a slope, on the east by the Northeast

quadrant, and on the south by the Southwest quadrant. Figure 2-2 is a schematic of the HRPM configuration used in the Northwest quadrant. The solid red

lines represent the nine optical paths used in the

configuration, each terminating at a mirror.
Former Landfill in Colorado Springs, Colorado

2-3

Figure 2-3. Schematic of the HRPM Configuration Used in the Southwest Quadrant.

Figure 2-4. Schematic of the HRPM configuration used in the northeast quadrant.

Figure 2-5. Schematic of the HRPM Configuration Used in the Southeast Quadrant.

2.1.2 Southwest Quadrant

The Southwest quadrant was bounded on the west

and south sides by a slope, on the east by the Southeast quadrant, and on the north by the Northwest

quadrant. Figure 2-3 is a schematic of the HRPM

configuration used in the Southwest quadrant. Due to

the shape of the quadrant, the configuration consisted

of only seven optical paths.

2.1.3 Northeast Quadrant

Figure 2-4 presents a schematic of the HRPM configuration used in the Northeast quadrant. The Northeast

quadrant was bounded on the east and north sides by

a slope, on the south by the Southeast quadrant, and

on the west by the Northwest quadrant. Due to the

size and shape of the quadrant, the configuration

consisted of only six optical paths.

2.1.4 Southeast Quadrant

The Southeast quadrant was bounded on the east and

south sides by a slope, on the west by the Southwest

quadrant, and on the north by the Northeast quadrant.

Figure 2-5 presents a schematic of the HRPM configuration used in the Southeast quadrant. Due to the

size and shape of the quadrant, the configuration

consisted of only five optical paths. 

2.2 VRPM Measurements

A VRPM survey was conducted along the northern

border of the site (see Figure 1-3). The VRPM

configuration consisted of one mirror placed on the

ground between the OP-FTIR and the scissors jack,

one mirror placed at the base of the scissors jack, two

mirrors placed on the scissors jack, and one mirror

placed on the ground beyond the scissors jack.

2.3 OP-TDLAS Measurements

The OP-TDLAS system was deployed for two days

of the field campaign to provide additional informa-
Evaluation of Fugitive Emissions at a

2-4

Figure 2-6. OP-TDLAS System.

Figure 2-8. Schematic of OP-TDLAS

Configuration Used on September 11.

Figure 2-7. Schematic of the OP-TDLAS

Configuration Used on September 10.

tion on methane concentrations at the site. Figure 2-6

is a picture of the OP-TDLAS system. The OPTDLAS collected data along the surface of the site on

September 10. On September 11, the instrument was

set up on a slope adjacent to the southern boundary of

the site, where a large amount of erosion was observed. Figures 2-7 and 2-8 present a schematic of the

OP-TDLAS configurations used on September 10

and 11, respectively. The distance of the path lengths

used in each OP-TDLAS configuration are presented

in Appendix B of this report.
Former Landfill in Colorado Springs, Colorado

3-1

Figure 3-1. Average Surface Methane Concentration Contour Map of

the Colorado Springs Landfill. 

Chapter 3

Results and Discussion

The results from the ORS data collected at the site are

presented in the following subsections. It should be

noted that the concentration values reported in the

following sections have not been corrected to standard atmospheric conditions. The measured methane

concentrations from the HRPM and VRPM surveys

are presented in Appendix C.

3.1 The Horizontal RPM Results

Figure 3-1 presents the average surface methane

concentration contour map of the entire site. The

contours give methane concentration values (in parts

per million) above an ambient background concentration of 1.55 ppm, which was the lowest methane

concentration measured during the field campaign.

The determination of this map is based on the mean

path-integrated methane concentration measurements

collected with the Unisearch OP-FTIR instrument in

the four quadrants, along 27 beam paths. The red X’s

show the location of the 27 mirrors used in the
Evaluation of Fugitive Emissions at a

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HRPM surveys, and the red dot shows the location of

the OP-FTIR/scanner used in the HRPM surveys. The

location of the VRPM survey is also shown in the

figure. The blue dot indicates the location of the

OP-FTIR/scanner used in the VRPM survey. The

figure shows the presence of a hot spot in the Northeast quadrant (denoted as hot spot “A” in Figure 3-1,

with concentrations greater than 0.4 ppm above

ambient background), and the Southeast quadrant

(denoted as hot spot “B” in Figure 3-1, with concentrations greater than 0.5 ppm above ambient background).

3.2 The Vertical RPM Results

As mentioned previously, the VRPM configuration

was located along the northern boundary of the site.

Table 3-1 presents methane emission flux determinations from the downwind VRPM survey. Figure 3-2

presents the reconstructed methane plume from the

VRPM survey of the site. Contour lines give methane

concentrations (in ppm) above an ambient background concentration of 1.55 ppm. The average

calculated methane flux from the site was 4.9 g/s.

Even though the observed wind direction was nearly

perpendicular to the VRPM configuration, this value

may be an underestimation of the actual emission rate

from the site.

Table 3-1. Moving Average of Calculated Methane

Flux, CCF, Wind Speed, and Wind Direction from

the VRPM Survey.

Cycles CCF Flux,

g/s

Wind

Speed,

m/s

Directiona

,

deg

1 to 4 0.959 5.7 4.9 15

2 to 5 0.960 5.8 4.9 14

3 to 6 0.930 5.3 4.7 17

4 to 7 0.932 4.3 4.9 17

5 to 8 0.930 4.3 4.8 20

6 to 9 0.914 3.9 5.0 19

7 to 10 0.893 5.0 4.9 14

8 to 11 0.934 6.1 4.5 12

9 to 12 0.926 5.4 4.4 5

Mean 0.931

Std. Dev. 0.0206

a Wind direction is measured from a vector normal to the plane of

the measurement configuration.

Figure 3-2 shows that the methane plume detected

during the VRPM survey was centered near the

location of the OP-FTIR/scanner (crosswind distance

between 0 and 100 meters) indicating that most of the

emissions originated from the eastern portion of the

site. Based on an analysis of the HRPM data presented in Figure 3-1 and wind data collected during

the VRPM survey, it is likely that the emissions from

hot spot “A” were completely captured by the VRPM

configuration. However, a portion of the emissions

from hot spot “B” (the most intense hot spot detected

during the HRPM survey) were probably not captured

by the VRPM configuration. Consequently, the

calculated methane flux may be underestimating the

actual emission rate from the site by as much as a

factor of two.

The methane concentrations measured during the

VRPM survey (peak concentrations of greater than

2.25 ppm above ambient background) are higher than

the surface methane concentrations measured during

the HRPM surveys (peak concentration of greater

than 0.5 ppm above ambient background). This is

probably due to the fact that the passive vents at the

site were sealed during the HRPM surveys, but were

not sealed during the VRPM survey.

Figure 3-3 presents a time series of calculated methane fluxes and the observed wind direction (from

normal to the configuration). The figure shows that

the largest methane flux values occurred when the

winds were close to perpendicular to the VRPM

configuration.

3.3 VOC and Ammonia Results

All data sets from the HRPM and VRPM surveys

were searched for the presence of VOCs and ammonia. The analysis detected the presence of gasoline

(primarily octane) during the HRPM survey of the

Northeast quadrant. However, this is attributed to

emissions from the gasoline generators used in the
Former Landfill in Colorado Springs, Colorado

3-3

Figure 3-2. Average Reconstructed Methane Plume from the VRPM Survey.

Figure 3-3. Methane Flux and Prevailing Wind Direction

Measured During the VRPM Survey.

field campaign, which were located upwind of the measurement configuration during the HRPM survey
Evaluation of Fugitive Emissions at a

3-4

of the Northeast quadrant. The measured gasoline

concentrations ranged from below detection level to

23 ppb.

Analysis of the other data sets did not reveal VOCs or

ammonia at levels higher than the minimum detection

level (MDL) of the OP-FTIR instruments. Table 3-2

presents the average MDL by compound of the

OP-FTIR for this field campaign.

Table 3-2. Minimum Detection Levels by Compound for the OP-FTIR Instrument.

Compound Average MDL,

ppb

Range,

ppb

Ammonia 8.4 3.6 to 20

Benzene 140 75 to 280

Ethanol 27 12 to 65

Gasoline 13 6.3 to 37

Methanol 17 7.2 to 41

Toluene 67 32 to 180

m-Xylene 45 22 to 120

o-Xylene 49 25 to 120

p-Xylene 59 28 to 160

3.4 OP-TDLAS Results

The OP-TDLAS system measured methane concentrations along the surface and on the slope adjacent to

the southern boundary of the site. Table 3-3 presents

the average methane concentrations (in parts per

million above an ambient background level of 1.55

ppm) measured at the site by the OP-TDLAS system.

Refer to Figures 2-7 and 2-8 for the location of the

beam paths used in each survey.

The survey of the surface found average methane

concentrations between 0.47 and 0.53 ppm above

ambient background levels. The surface methane

concentrations measured with the OP-TDLAS system

agree fairly well with the levels found in hot spots

identified during the HRPM surveys.

Table 3-3. Average Methane Concentrations

above Ambient Background Levels Measured

with the OP-TDLAS System.

Beam

Path

Survey of

Surface

9/10/03

Survey of

Slope

9/11/03

1 Average 0.53 0.74

Std. Dev. 0.05 0.13

2 Average 0.51 1.07

Std. Dev. 0.05 0.16

3 Average 0.52 0.78

Std. Dev. 0.03 0.15

4 Average 0.51 0.55

Std. Dev. 0.01 0.12

5 Average 0.51 0.89

Std. Dev. 0.05 0.27

6 Average 0.51 0.55

Std. Dev. 0.02 0.20

7 Average 0.47 1.34

Std. Dev. 0.02 0.33

8 Average 0.49 0.47

Std. Dev. 0.02 0.22

The survey of the slope along the southern boundary

of the site found relatively higher methane concentrations. The largest average methane concentrations

were detected along beam path #2 (1.07 ppm above

ambient background) and beam path #7 (1.34 ppm

above ambient background). The relatively larger

standard deviations found during the survey of the

slope suggest that methane hot spots were present

along the slope.
Former Landfill in Colorado Springs, Colorado

4-1

Chapter 4

Conclusion

This report presents the results from a field campaign

conducted in September 2003 at a former landfill site

in Colorado Springs, Colorado. The study used

measurements from ground-based ORS instruments

and the ORS-RPM method to characterize fugitive

emissions of methane and VOCs from the site.

HRPM surveys of the site detected the presence of

two methane hot spots located along the eastern side

of the site. The first methane hot spot, located in the

Northeast quadrant, had concentrations greater than

0.4 ppm above an ambient background concentration

of 1.55 ppm. The other hot spot was located in the

Southeast quadrant and had concentrations greater

than 0.5 ppm above ambient background levels.

The HRPM survey of the Northeast quadrant detected

the presence of gasoline at concentrations ranging

from below detection level to 23 ppb. This was

attributed to the field operations based on analysis of

the observed wind. The data sets from the HRPM and

VRPM surveys were searched for the presence of

VOCs and ammonia. Analysis did not detect VOCs

or ammonia at levels higher than the minimum

detection level (MDL) of the OP-FTIR instruments.

The VRPM configuration was set up along the

northern boundary of the site. The calculated methane

flux from the site was 4.9 g/s. The peak of the methane plume measured during the VRPM survey was

located close to the location of the OP-FTIR/scanner.

This agrees well with the location of the methane hot

spots detected during the HRPM survey, indicating

that the hot spots may be a major source of the

methane plume detected during the VRPM survey.

The OP-TDLAS system collected information on

methane concentrations along the surface of the site

and on a slope adjacent to the southern boundary of

the site. The survey of the surface found average

methane concentrations between 0.47 ppm and 0.53

ppm above ambient background levels. These values

agree fairly well with the methane levels found in hot

spots identified during the HRPM surveys.

The survey of the slope along the southern boundary

of the site found slightly elevated methane concentrations. The largest average measured methane concentration was 1.34 ppm above ambient background

levels. The relatively larger standard deviations found

during the slope survey suggest that methane hot

spots were present along the slope.

The schedule of the field campaign allowed for only

three days of data collection. HRPM data was collected during the first two days of the campaign, and

VRPM data was collected during the last day. Due to

a change in prevailing wind direction during the last

day of the campaign, the VRPM configuration had to

be relocated. Consequently, only about one hour

worth of VRPM data was collected. For future

campaigns, it is recommended that more time be

allocated for VRPM data collection to ensure that a

larger data set is obtained. This would provide more

information on flux variations from the site due to

differing weather conditions.

The site contained several passive vents located

approximately 2 meters above the surface. These

vents were sealed during the HRPM surveys because

they were suspected emissions hot spots, and may

have masked other emissions hot spots located along

the surface of the site. The seals were removed from

the vents for the VRPM survey. This may not have
Evaluation of Fugitive Emissions at a

4-2

been the best approach for characterizing the surface

emissions from this site.

Future monitoring of this site using the ORS-RPM

method with alternate configurations may be warranted in order to get a more definitive methane flux

value, and to address the issues above.
Former Landfill in Colorado Springs, Colorado

5-1

Table 5-1. Instrumentation Calibration Frequency and Description.

Instrument Measurement Calibration Date Calibration Detail

Climatronics Model

101990-G1 Meteorological

Heads

Wind speed in miles

per hour

22 April 2003 APPCD Metrology Lab cal. records

on file

Climatronics Model

101990-G1 Meteorological

Heads

Wind direction in

degrees from north

22 April 2003 APPCD Metrology Lab cal. records

on file

Topcon Model GTS-211D

Theodolite

Distance 1 May 2003 Actual distance = 50 ft

Measured distance = 50.6 and 50.5

ft

Topcon Model GTS-211D

Theodolite

Angle 21 May 2003 Actual angle = 360°

Measured angle = 359° 41N 18O and

359° 59N 55O

Chapter 5

Quality Assurance/Quality Control

5.1 Equipment Calibration

As stated in the ECPD Optical Remote Sensing

Facility Manual (U.S. EPA, 2004), all equipment is

calibrated annually or cal-checked as part of standard

operating procedures. Certificates of calibration are

kept on file. Maintenance records are kept for any

equipment adjustments or repairs in bound project

notebooks that include the data and description of

maintenance performed. Instrument calibration

procedures and frequency are listed in Table 5-1 and

further described in the text.

As part of the preparation for this project, a Category

III Quality Assurance Project Plan (QAPP) was

prepared and approved for each separate field campaign. In addition, standard operating procedures

were in place during the field campaign.

5.2 Assessment of DQI Goals

The critical measurements associated with this

project and the established data quality indicator

(DQI) goals in terms of accuracy, precision, and

completeness are listed in Table 5-2. More information on the procedures used to assess DQI goals can

be found in Section 10 of the ECPD Optical Remote

Sensing Facility Manual (U.S. EPA, 2004).

5.2.1 DQI Check for Analyte PIC Measurement

The precision and accuracy of the analyte pathintegrated concentration (PIC) measurements was

assessed by analyzing the measured nitrous oxide

concentrations in the atmosphere. A typical background atmospheric concentration for nitrous oxide

is about 315 ppb. However, this value may fluctuate
Evaluation of Fugitive Emissions at a

5-2

Table 5-2. DQI Goals for Instrumentation.

Measurement

Parameter Analysis Method Accuracy Precision DetectionLimit Completeness

Analyte PIC OP-FTIR: nitrous oxide

concentrations

±25%, ±15%, ±10%a ±10% See Table 1-1 90%

Ambient Wind

Speed

Climatronics met heads sideby-side comparison in the

field

±1 m/s ±1 m/s N/A 90%

Ambient Wind

Direction

Climatronics met heads sideby-side comparison in the

field

±10° ±10° N/A 90%

Distance

Measurement

Topcon Theodolite ±1 m ±1 m 0.1 m 100%

a

 The accuracy acceptance criterion of ±25% is for pathlengths of less than 50 m, ±15% is for pathlengths between 50 and 100 m, and ±10%

is for pathlengths greater than 100 m.

due to seasonal variations in nitrous oxide concentrations or elevation of the site. The elevation of the site

surveyed in this field campaign is approximately

6,000 ft above sea level. At this elevation, the optical

density of a nitrous oxide concentration of 315 ppb

would be equivalent to a lower concentration of

nitrous oxide at sea level, due to the decreased air

density. To correct the background nitrous oxide

level for the effects of elevation, the measured

temperature and atmospheric pressure were ratioed to

standard temperature and pressure values. The

corrected background nitrous oxide concentration for

this site is approximately 249 ppb.

The precision of the analyte PIC measurements was

evaluated by calculating the relative standard deviation of each data subset. A subset is defined as the

data collected along one particular path length during

one particular survey in one survey sub-area. The

number of data points in a data subset depends on the

number of cycles used in a particular survey.

The accuracy of the analyte PIC measurements was

evaluated by comparing the calculated nitrous oxide

concentrations from each data subsets to the corrected background concentration of 249 ppb. The

number of calculated nitrous oxide concentrations

that failed to meet the DQI accuracy criterion in each

data subset was recorded.

Overall, 39 data subsets were analyzed from this field

campaign. Based on the DQI criterion set forth for

precision of ±10%, each of the 39 data subsets were

found to be acceptable. The range of calculated

relative standard deviations for the data subsets from

this field campaign was 0.54 to 6.9 ppbm, which

represents 0.22 to 2.8% RSD.

Each data point (calculated nitrous oxide concentration) in the 39 data subsets were analyzed to assess

whether or not it met the DQI criterion for accuracy

of ±25% (249 ± 62 ppb) for path lengths less than 50

meters, ±15% (249 ± 37 ppb) for path lengths between 50 and 100 meters, and ±10% (249 ± 25 ppb)

for path lengths greater than 100 meters. A total of

646 data points were analyzed, and all met the DQI

criteria for accuracy. Based on the DQI criterion set

forth for accuracy and precision, all data points were

found to be acceptable, for a total completeness of

100%.

5.2.2 DQI Checks for Ambient Wind Speed

and Wind Direction Measurements

Section 10 of the ECPD Optical Remote Sensing
Former Landfill in Colorado Springs, Colorado

5-3

Facility Manual (U.S. EPA, 2004) states that the DQI

goals for precision and accuracy of the Climatronics

meteorological heads are assessed by collecting

meteorological data for 10 minutes with the two

heads set up side-by side. This was not done prior to

the current field campaign because this DQI procedure had not been implemented at the time of the

study. However, the Climatronics heads were calibrated in April 2003 by the APPCD Metrology Lab

(see Table 5-1). Additionally, checks for agreement

of the wind speed and wind direction measured from

the two heads (2 m and 10 m) were done in the field

during data collection. Although 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. Another check is done in the field by comparing the

measured wind direction to the forecasted wind

direction for that particular day.

5.2.3 DQI Check for Precision and Accuracy

of Theodolite Measurements

Although calibration of this instrument did not occur

immediately prior to this field campaign, the theodolite was originally calibrated by the manufacturer

prior to being received by the U.S. EPA. Additionally, there are several internal checks in the theodolite

software that prevent data collection from occurring

if the instrument is not properly aligned on the object

being measured or if the instrument has not been

balanced correctly. When this occurs, it is necessary

to re-initialize the instrument to collect data.

Prior to this field campaign, DQI checks were performed on the theodolite during May 2003 at a field

site near Chapel Hill, NC. The calibration of distance

measurement was done using a tape measure to

compare the actual distance to the measured distance.

This check was duplicated to test the precision of this

measurement. The actual distance measured was 15.2

m. The measured distance during the first test was

15.4 m, and the measured distance during the second

test was 15.4 m. The results indicate the accuracy

(1.3% bias for test one and two) and precision (0%

RSD) of the distance measurement fell well within

the DQI goals.

The check to test the precision and accuracy of the

angle measurement was done by placing two mirror

targets approximately 180 degrees apart. The theodolite was placed in the middle of the imaginary circle

formed by the two mirrors. Thus, the actual angle was

360°. The angle measured during the first test was

359° 41N 18O, and the angle measured during the

second test was 359° 59N 55O. The results indicate the

accuracy and precision of the angle measurement fall

well within the DQI goals.

5.3 QC Checks of OP-FTIR Instrument

Performance

Several checks should be performed on the OP-FTIR

instrumentation prior to deployment to the field and

during the duration of the field campaign. More

information on these checks can be found in MOP

6802 and 6807 of the ECPD Optical Remote Sensing

Facility Manual. At the time of the current field

campaign, the procedures and schedule of QC checks

were still being developed. Consequently, QC checks

were performed only in the field on the Unisearch

OP-FTIR.

On the first day of the field campaign (September

10), the single beam ratio, signal-to-noise, baseline

stability, electronic noise, saturation, and random

baseline noise tests were performed on the Unisearch

OP-FTIR. The results of the tests indicated that the

instrument was operating within the acceptable

criteria range.

On September 11, the signal-to-noise, and single

beam ratio tests were performed on the Unisearch

OP-FTIR. The results of these tests indicated that the

instrument was operating within the acceptable

criteria range.

In addition to the QC checks performed on the

OP-FTIR, the quality of the instrument signal

(interferogram) was checked constantly during the

field campaign. This was done by ensuring that the

intensity of the signal is at least 5 times the intensity

of the stray light signal (the stray light signal is

collected as background data prior to actual data
Evaluation of Fugitive Emissions at a

5-4

Figure 3-4. Comparison of a spectrum

Measured at the Site (green trace) to Reference

Spectra of Gasoline (red trace).

collection and measures internal stray light from the

instrument itself). In addition to checking the strength

of the signal, checks were done constantly in the field

to ensure that the data were being collected and

stored to the data collection computer. During the

campaign, a member of the field team constantly

monitored the data collection computer to make sure

these checks were completed.

5.4 Validation of Concentration Data

Collected with the OP-FTIR

During the analysis of the OP-FTIR data, a validation

procedure was performed to aid in identifying the

presence of gasoline in the dataset. This validation

procedure involves visually comparing an example of

the measured spectra to a laboratory-measured

reference spectrum.

Figure 3-4 shows an example of a validation done

using a spectrum collected during the HRPM survey

of the Northeast quadrant. Gasoline was detected in

this particular spectrum. The gasoline features can be

seen in the measured field spectrum (green trace).

Classical Least Squares (CLS) analysis performed on

this spectrum resulted in determinations of 22.0 ± 6.5

ppb of gasoline. The uncertainty value is equal to

three times the standard error in the regression fit of

the measured spectrum to a calibrated reference

spectrum.

5.5 Internal Audit of Data Input Files

An internal audit was performed by the ARCADIS

Field Team Leader on a sample of approximately

10% of the data from the field campaign. The audit

investigated the accuracy of the input files used in

running the RPM programs. The input files contain

analyzed concentration data, mirror path lengths, and

wind data. The results of this audit found no problems with the accuracy of the input files created.

5.6 OP-TDLAS Instrument

At the time of the field campaign, the OP-TDLAS

system had only recently been acquired by EPA.

Consequently, standard operating and calibration

procedures were still being developed. Many improvements have been made to the QA procedures for

this instrument since this field campaign. Some of

these improvements include the development of

calibration cells, and the development of a standard

operating procedure for collecting emissions measurements with the OP-TDLAS (see MOP 6811 of

the ECPD Optical Remote Sensing Facility Manual).

The results of the current field campaign present

methane concentrations measured with the OP-FTIR

instrument and the OP-TDLAS system. In order to

evaluate the comparability of measurements from the

two instruments, an experiment was done in January

2004 to compare methane concentrations measured

with the OP-TDLAS system and the IMACC

OP-FTIR. Figure 3-5 shows the results of this experiment. The results show that methane concentrations

measured with the OP-TDLAS were slightly higher

(3%) than concentrations measured with the OPFTIR instrument.
Former Landfill in Colorado Springs, Colorado

5-5

Figure 5-2.Post-Colorado Springs Comparison

of Methane Concentrations Measured with the

OP-TDLAS and OP-FTIR Instruments.
Evaluation of Fugitive Emissions at a

5-6
Former Landfill in Colorado Springs, Colorado

6-1

Chapter 6

List of References

Hashmonay, R.A., M.G. Yost, D.B. Harris, and E.L. Thompson (1998), 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,

pp. 405-410.

Hashmonay, R.A., and M.G. Yost (1999), Innovative approach for estimating fugitive gaseous fluxes using

computed tomography and remote optical sensing techniques, J. Air Waste Manage. Assoc., 49:8, pp. 966-972.

Hashmonay, R.A., M.G. Yost, and C. Wu (1999), Computed tomography of air pollutants using radial scanning

path-integrated optical remote sensing, Atmos. Environ., 33:2, pp. 267-274.

Hashmonay, R.A., D.F. Natschke, K.Wagoner, D.B. Harris, E.L.Thompson, and M.G. Yost (2001), Field

evaluation of a method for estimating gaseous fluxes from area sources using open-path Fourier transform

infrared, Environ. Sci. Technol., 35:11, pp. 2309-2313.

Hashmonay, R.A., K. Wagoner, D.F. Natschke, D.B. Harris, and E.L. Thompson (2002), Radial computed

tomography of air contaminants using optical remote sensing, presented June 23-27, 2002 at the AWMA 95th

Annual Conference and Exhibition, Baltimore, MD.

Platt, U. (1994), Differential optical absorption spectroscopy (DOAS), In: Air Monitoring by Spectroscopic

Techniques, Chemical Analysis Series, Vol. 127, John Wiley & Sons, Inc. pp. 27-84.

U.S. EPA QA/G4 (2000), Guidance for the Data Quality Objectives Process, EPA-600/R-96/055, Office of

Environmental Information, U.S. EPA, Washington, DC. Also at 

http://www.epa.gov/quality/qs-docs/g4-final.pdf (accessed April 2005).

U.S. EPA (2004), ECPB Optical Remote Sensing Facility Draft Facility Manual, approved April.

Wu, C., M.G. Yost, R.A. Hashmonay, and D.Y. Park (1999), Experimental evaluation of a radial beam

geometry for mapping air pollutants using optical remote sensing and computed tomography, Atmos. Environ.,

33:28, pp. 4709-4716.
Evaluation of Fugitive Emissions at a

6-2
Former Landfill in Colorado Springs, Colorado

A-1

Appendix A

OP-FTIR Mirror Coordinates

Table A-1. Standard Distance and Horizontal

Coordinates of Mirrors Used in the HRPM Survey

of Northwest Quadrant.

Mirror

Number

Standard

Distance

(m)

Horizontal Angle

from North 

(degrees)

1 120 244

2 87.1 253

3 120 263

4 106 273

5 143 276

6 56.7 279

7 141 293

8 83.3 305

9 114 311

Table A-2. Standard Distance and Horizontal

Coordinates of Mirrors Used in the HRPM Survey

of Southwest Quadrant.

Mirror

Number

Standard

Distance

(m)

Horizontal Angle

from North 

(degrees)

1 135 149

2 112 156

3 135 180

4 68.9 181

5 155 192

6 95.6 208

7 131 217

Table A-3. Standard Distance and Horizontal

Coordinates of Mirrors Used in the HRPM Survey

of Northeast Quadrant.

Mirror

Number

Standard

Distance

(m)

Horizontal Angle

from North 

(degrees)

1 115 327

2 90.5 338

3 70.8 5

4 140 7

5 188 21

6 117 30

7 173 56

Table A-4. Standard Distance and Horizontal

Coordinates of Mirrors Used in the HRPM Survey

of Southeast Quadrant.

Mirror

Number

Standard

Distance

(m)

Horizontal Angle

from North 

(degrees)

1 117 68

2 74.1 92

3 130 95

4 108 119

5 158 127
Evaluation of Fugitive Emissions at a

A-2

Table A-5. Standard Distance, and Horizontal and

Vertical Coordinates of Mirrors Used in the VRPM

Survey of the Northern Border.

Mirror

Number

Standard

Distance

(m)

Horizontal

Angle from

North 

(degrees)

Vertical Anglea

(degrees)

1 116 235 0

2 179 233 0

3 282 234 0

4 180 233 2

5 179 233 5 a Vertical angle shown is the angle from horizontal (positive values

indicate elevation from the horizontal, negative values indicate

descent from the horizontal).
Former Landfill in Colorado Springs, Colorado

B-1

Appendix B

OP-TDLAS Configuration Path Length Distances

Table B-1. Distance of Path Lengths Used in OP-TDLAS Configurations.

Mirror Number

Surface Survey

on 9/10/03

(m)

Slope Adjacent to

Southern Boundary Surveyed on 9/11/03

(m)

1 205 225

2 134 235

3 238 179

4 314 179

5 141 177

6 281 176

7 149 170

8 307 158
Evaluation of Fugitive Emissions at a

B-2
Former Landfill in Colorado Springs, Colorado

C-1

Appendix C

Methane Concentrations

Table C-1. Methane Concentrations Found during the HRPM Survey of the Northeast Quadrant.

Cycle

Methane Concentration

(ppm)

Mirror 1 Mirror 2 Mirror 3 Mirror 4 Mirror 5 Mirror 6 Mirror 7

1 1.81 1.78 1.95 1.80 1.73 1.78 1.75

2 1.82 1.78 1.78 1.94 1.95 1.77 1.74

3 1.86 1.76 1.79 1.94 1.92 1.86 1.82

4 1.93 1.82 1.78 2.09 1.89 1.81 1.75

5 1.81 1.72 1.77 1.74 1.81 1.80 1.76

6 1.81 1.86 1.90 2.19 1.90 1.96 1.99

7 1.89 1.97 2.13 1.97 1.79 1.96 1.93

8 1.83 1.77 1.83 1.84 1.80 1.76 1.77

9 1.78 1.82 1.94 1.88 1.81 1.78 1.80

10 1.86 1.83 1.89 1.79 1.73 1.75 1.72

11 1.75 1.75 1.80 1.77 1.73 1.76 1.72

12 1.76 1.78 1.87 1.85 1.77 1.76 1.76

13 1.75 1.81 1.90 1.85 1.79 1.90 1.86

14 1.82 1.91 1.96 1.98 1.94 1.93 1.81

15 1.88 1.88 1.88 2.02 1.85 1.84 1.75

16 1.90 1.90 1.85 1.93 1.78 1.76 1.75

17 1.74 1.74 1.84 1.79 1.84 1.78 1.75

18 1.98 1.78 1.80 1.92 1.84 1.84 1.76
Evaluation of Fugitive Emissions at a

C-2

Table C-2. Methane Concentrations Found during the HRPM Survey of the Northwest Quadrant.

Cycle

Methane Concentration

(ppm)

Mirror 1 Mirror 2 Mirror 3 Mirror 4 Mirror 5 Mirror 6 Mirror 7 Mirror 8 Mirror 9

1 1.63 1.65 1.60 1.62 1.60 1.66 1.61 1.60 1.57

2 1.61 1.65 1.59 1.61 1.59 1.64 1.60 1.60 1.59

3 1.64 1.64 1.59 1.62 1.60 1.66 1.60 1.62 1.59

4 1.61 1.65 1.61 1.61 1.58 1.64 1.59 1.60 1.58

5 1.64 1.65 1.59 1.60 1.59 1.63 1.60 1.60 1.55

6 1.61 1.63 1.60 1.59 1.60 1.65 1.61 1.60 1.58

7 1.63 1.64 1.60 1.61 1.58 1.63 1.60 1.60 1.60

8 1.60 1.63 1.58 1.58 1.58 1.65 1.59 1.62 1.60

9 1.63 1.66 1.61 1.61 1.58 1.65 1.63 1.63 1.60

10 1.62 1.67 1.62 1.60 1.62 1.67 1.63 1.63 1.61

11 1.63 1.66 1.62 1.61 1.61 1.66 1.63 1.63 1.61

12 1.64 1.67 1.63 1.64 1.62 1.68 1.64 1.64 1.61

13 1.64 1.67 1.63 1.64 1.63 1.69 1.65 1.66 1.62

14 1.65 1.66 1.62 1.63 1.63 1.66 1.61 1.64 1.62

15 1.66 1.67 1.63 1.66 1.62 1.67 1.62 1.63 1.61
Former Landfill in Colorado Springs, Colorado

C-3

Table C-3. Methane Concentrations Found during the HRPM Survey of the Southeast Quadrant.

Cycle

Methane Concentration

(ppm)

Mirror 1 Mirror 2 Mirror 3 Mirror 4 Mirror 5

1 1.84 1.83 2.08 1.87 1.76

2 1.75 1.90 1.83 1.76 1.83

3 1.84 1.78 1.97 1.75 1.86

4 1.81 1.89 1.76 1.81 1.73

5 1.91 2.18 2.10 1.75 1.98

6 1.80 1.81 2.11 1.84 1.80

7 1.78 1.85 1.86 1.79 1.77

8 1.88 1.92 2.20 1.86 1.76

9 1.84 1.81 1.84 1.72 1.89

10 1.85 1.92 1.79 1.76 1.85

11 1.84 1.90 1.77 1.76 1.86

12 1.84 1.87 1.97 1.77 1.80

13 1.88 1.97 1.88 1.78 1.75

14 1.88 2.21 1.99 1.78 1.75

15 1.74 1.83 2.03 1.73 1.81

16 1.73 1.93 1.79 1.84 1.94

17 1.82 1.94 1.96 1.84 1.98

18 1.94 1.94 2.04 1.94 1.96

19 1.78 2.00 1.89 1.89 1.95

20 1.98 1.85 1.90 1.86 1.91

21 1.84 1.93 1.83 1.88 1.96

22 1.87 1.86 1.88 1.80 2.01

23 1.76 1.92 2.02 1.79 1.87

24 1.85 1.93 2.13 1.91 1.83

25 1.79 1.92 2.24 1.82 1.77
Evaluation of Fugitive Emissions at a

C-4

Table C-4. Methane Concentrations Found during the HRPM Survey of the Southwest Quadrant.

Cycle

Methane Concentration

(ppm)

Mirror 1 Mirror 2 Mirror 3 Mirror 4 Mirror 5 Mirror 6 Mirror 7

1 1.76 1.77 1.74 1.80 1.73 1.74 1.75

2 1.75 1.79 1.76 1.79 1.75 1.77 1.75

3 1.76 1.75 1.75 1.80 1.75 1.77 1.75

4 1.76 1.77 1.76 1.80 1.74 1.75 1.70

5 1.76 1.80 1.74 1.79 1.73 1.76 1.75

6 1.74 1.75 1.75 1.78 1.75 1.79 1.74

7 1.74 1.77 1.74 1.81 1.76 1.79 1.79

8 1.78 1.78 1.75 1.81 1.76 1.78 1.74

9 1.73 1.75 1.73 1.78 1.73 1.75 1.77

10 1.74 1.76 1.74 1.79 1.73 1.77 1.73

11 1.73 1.75 1.75 1.80 1.75 1.76 1.73

12 1.73 1.75 1.73 1.78 1.73 1.76 1.77

13 1.74 1.75 1.74 1.78 1.75 1.79 1.83

14 1.76 1.76 1.73 1.78 1.74 1.78 1.80

15 1.77 1.75 1.72 1.79 1.74 1.78 1.80

16 1.74 1.79 1.73 1.77 1.74 1.77 1.79

17 1.73 1.76 1.73 1.78 1.75 1.76 1.78

18 1.77 1.75 1.71 1.77 1.72 1.75 1.77

19 1.73 1.75 1.71 1.77 1.71 1.75 1.91

20 1.74 1.78 1.71 1.77 1.76 1.77 1.74
Former Landfill in Colorado Springs, Colorado

C-5

Table C-5. Methane Concentrations Found during the VRPM Survey.

Cycle

Methane Concentration

(ppm)

Mirror 1 Mirror 2 Mirror 3 Mirror 4 Mirror 5

1 4.03 3.86 3.28 3.06 2.59

2 4.42 3.61 3.17 2.79 2.36

3 3.55 3.68 3.36 2.81 2.42

4 3.69 3.89 3.28 2.97 2.54

5 4.32 4.15 3.58 3.16 2.71

6 3.75 3.49 2.79 2.39 2.34

7 4.73 3.14 2.84 2.72 2.69

8 3.82 3.25 3.12 3.11 2.60

9 3.96 3.74 3.12 2.76 2.41

10 3.77 3.52 2.77 2.79 2.79

11 3.80 3.64 3.21 3.00 2.46

12 3.60 3.41 3.02 2.85 2.23
C-6

ARCADIS G&M, Inc

4915 Prospectus Dr. Suite F,

Durham, NC 27713

TECHNICAL REPORT DATA

(Please read Instructions on the reverse before completing)

1. REPORT NO. 2. 3. RECIPIENT'S ACCESSION NO.

EPA-600/R-05/041

4. TITLE AND SUBTITLE 5. REPORT DATE

Evaluation of Fugitive Emissions at a Former Landfill Site in

Colorado Springs, Colorado Using Ground-Based Optical

Remote Sensing Technology

 April 2005

6. PERFORMING ORGANIZATION CODE

7. AUTHORS 8. PERFORMING ORGANIZATION REPORT NO.

M. Modrak, R.A. Hashmonay, R. Varma, R. Kagann

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO.

11. CONTRACT/GRANT NO.

EP-C-04-023, WA 0-25

12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED

U. S. EPA, Office of Research and Development

Air Pollution Prevention and Control Division

Research Triangle Park, North Carolina 27711

Final; 09/2003–09/2004

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, e-mail

thorneloe.susan@epa.gov

16. ABSTRACT

The report describes an assessment of fugitive landfill gas emissions of methane and VOCs at a former

landfill site in Fort Collins, Colorado. The current owners of the landfill and the State of Colorado requested

assistance from the EPA to search for any fugitive gas emissions from the former landfill site. This

assessment was necessary due to the potential adverse health effects associated with exposure to landfill

gas. An open-path Fourier transform infrared spectrometer, open-path tunable diode laser absorption

spectroscopy, and an ultra-violet differential optical absorption spectrometer were used to make the

assessment survey. The survey detected a methane hot spot in the Northeast quadrant of the site, and the

peak concentration for this hot spot was greater than 0.4 ppm above ambient background levels. Another

methane hot spot was detected in the Southeast quadrant of the site, and the peak concentration for this

hot spot was greater than 0.5 ppm above ambient background. The survey measured an average methane

flux from the site of 4.9 g/s. The location of the peak of the reconstructed methane plume agrees well with

the location of the hot spots, which suggests that emissions from the two hot spots are a major source of

the methane plume.

17. KEY WORDS AND DOCUMENT ANALYSIS

a. DESCRIPTORS b. IDENTIFIERS/OPEN ENDED TERMS c. COSATI Field/Group

Air Pollution

Earth Fills (Landfill)

Emissions

Organic Compounds

Methane

Ammonia

Gasoline

Pollution Control

Stationary Sources

13B

13C

14G

07C

07B

21D

18. DISTRIBUTION STATEMENT 19. SECURITY CLASS (This Report) 21. NO. OF PAGES

Release to Public

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20. SECURITY CLASS (This Page) 22. PRICE

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