Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

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Chapter 3 Results and Discussion The results from the measurement campaign are presented in the following subsections, including the calculated methane flux values from each landfill cell, total site methane emission rates, data on VOC constituents in the landfill gas from each site, and data on total, elemental and organo-mercury (including methyl- and dimethyl- mercury) collected in the vicinity of the gas header pipes at the sites. The methane concentrations used to calculate methane flux values from each cell are presented in Appendix C of this document. As mentioned previously, background methane concentration measurements were collected at each site to establish a background methane concentration value. Although measurements were collected at Site #1 in an area upwind of the measurement cells, the measurement location was still within the boundaries of the landfill facility. The average methane concentration found from the background survey at Site #1 was 3.1 ± 1.68 ppm. The fact that the standard deviation of the measurement is high (almost equal to the expected atmospheric background value of 1.7 ppm) indicates that there were methane sources captured by the background measurement configuration. Therefore, the background data collected at Site #1 does not represent a true site background measurement. Due to this, we used an accepted global methane background value of 1.7 ppm. The average methane concentration from the background survey performed at Site #2 was 1.7 ± 0.376 ppm. The background values from each site were subtracted from all raw methane concentrations prior to calculating methane flux values from the sites. During the Site #1 measurement campaign, an inter-comparison study was performed between the OP-FTIR and OP-TDLAS instruments. The objective of the study was to assess the comparability of the two instruments by deploying them along the same optical path and comparing the measured path-averaged methane concentrations. Due to project time constraints, the inter-comparison study was not performed over an adequate period of time to obtain reliable data. Ideally this should have been done during the study at each site. However, for the reporting of this data and based on previous studies where both instruments were compared over adequate time periods, it is assumed that the two instruments provide identical results for methane concentration measurements. Further information is presented in Section 5. 3.1 Landfill Site #1 3.1.1 Control Cell ORS measurements were collected in the control cell on February 20. A schematic of the ORS measurement configuration from this cell can be found in Figure 2-1. Although measurements were collected in this cell for several hours, problems were encountered with the alignment of the OP-TDLAS beams on the retro-reflecting mirror targets, as the synthetic liner on the surface of the cell did not provide a firm surface to deploy the OP-TDLAS scanner. After the instrument 3-1
was aligned on the mirror targets in the configuration, the scanner positions drifted after a short period of time due to slight movement of the scanner base, and eventually the instrument was completely misaligned on all mirrors. Consequently, it was necessary to stop data acquisition, and re-align the instrument on all mirrors in the configuration. This problem was especially evident along the long VRPM configuration, located along the southern boundary of the cell. Due to this problem, there are limited ORS data from this survey, especially data from the long OP-TDLAS configuration located along the southern boundary of the cell. In fact, data was collected along only the longest surface beam path of this configuration (mirror target located at the base of the vertical structure) in order to obtain enough information to estimate the methane flux value along this VRPM plane. Emissions data presented in this section are from two surveys. The flux values presented in the tables in this section represent a moving average of three measurement cycles, where a cycle is defined as data collected along each measurement path in the configuration. The time of the flux measurements presented in the tables represents the midpoint time of the averaging period, where the averaging period is approximately 15 minutes. Figure 3-1 presents a summary of the actual measurement configurations used in the cell, as well as the measurement results from the first survey conducted at 4:00 p.m. Figure 3-2 presents the measurement results from the second survey conducted at 5:00 p.m. The figures depict the average calculated methane flux values along each VRPM measurement plane during each survey. The blue arrow depicts the prevailing wind values during the time of the measurements. Figure 3-1. Summary of ORS measurements from the 4:00 pm survey of the control cell of Site #1 3-2
Page 1 and 2: Quantifying Uncontrolled Landfill G
Page 3 and 4: Foreword The U.S. Environmental Pro
Page 5 and 6: 3.1.3 Total Site Methane Emissions
Page 7 and 8: List of Tables Table 1-1. Target Co
Page 9 and 10: Table 3-28. Calculated Methane Flux
Page 11 and 12: Table C-6. Methane Concentrations (
Page 13 and 14: List of Figures Figure 1-1. Map of
Page 15 and 16: Executive Summary Waste decompositi
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Page 19 and 20: instrument (IMACC, Inc.). Figures 1
Page 21 and 22: Figure 1-3. Scanning Boreal GasFind
Page 23 and 24: wind direction data are collected n
Page 25 and 26: adsorption spectrometer. The analyz
Page 27 and 28: Table 1-2. Schedule of Work Perform
Page 29 and 30: Figure 2-2. Detail of measurement c
Page 31 and 32: corners of the cell, respectively.
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Page 39 and 40: methane concentrations measured alo
Page 41 and 42: Figure 3-3 Summary of ORS measureme
Page 43 and 44: Table 3-5. Calculated methane flux
Page 45 and 46: Table 3-7. Calculated methane flux
Page 47 and 48: cell to the base. The following equ
Page 49 and 50: Table 3-9. Results of TO-15 analysi
Page 51 and 52: Table 3-10. Results of C1 to C6 and
Page 53 and 54: Table 3-14. Monomethyl Mercury Conc
Page 55 and 56: 3.2 Landfill Site #2 3.2.1 Control
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Page 71 and 72: Table 3-34. Results for C1 to C6 an
Page 73 and 74: Table 3-38. Monomethyl Mercury Conc
Page 75 and 76: 3.3 Gas and Mercury Sampling Result
Page 77 and 78: Site #1 with a level of 83 ppmv. Th
Page 79 and 80: The surveys also found significant
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the measured path-integrated methan
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5.2.7 DQI Check of Total Mercury Sa
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Site #1 5.4 Site #2 77.9 Completene
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U.S. Environmental Protection Agenc
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d f e c b PDCs Y X a 2 12( y)( z) (
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When the VRPM configuration consist
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Table B-3. Distance, and Horizontal
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Table B-7. Distance, and Horizontal
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APPENDIX C Path-Averaged Methane Co
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Table C-3. Methane Concentrations (
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Table C-11. Methane Concentrations
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