Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

More documents

Recommendations

Info

315 ppb. The number of calculated nitrous oxide concentrations that failed to meet the DQI accuracy criterion in each data subset was recorded. Overall, 180 data subsets were analyzed from this field campaign. Based on the DQI criterion set forth for precision of ±10 percent, all of the data subsets were found to be acceptable for a completeness of 100 percent. The range of calculated relative standard deviations for the data subsets from this field campaign was 0.36 to 17.4 ppb, which represents 0.11- to 5.5-percent RSD. Each data point (calculated nitrous oxide concentration) in the data subsets was analyzed to assess whether or not it met the DQI criterion for accuracy of ±25 percent (315 ± 79 ppb) for path lengths less than 50 meters, ±15 percent (315 ± 47 ppb) for path lengths between 50 and 100 meters, and ±10 percent (315 ± 32 ppb) for path lengths greater than 100 meters. A total of 1569 data points were analyzed, and 1482 met the DQI criteria for accuracy, for a total completeness of 94 percent. 5.2.3 Inter-comparison Study of OP-FTIR and OP-TDLAS Instruments Operational difficulties were encountered in the field that resulted in scaling back the study to the extent that the results are not considered reliable. Whenever two different types of instruments are used (i.e., OP-FTIR and OP-TDLAS), field interlaboratory comparison is recommended. This is to ensure that there is no potential bias between measurements. At each survey area, the instruments were to be located diagonally across the survey area and operated for ~30 minutes to collect methane concentration data across the same optical path. The study was performed for Site #1 using the same optical path with a distance of ~200 meters. Data were collected with the OP-FTIR for approximately 10 minutes and with the OP-TDLAS for about 20 minutes. Overlapping data for the comparison were available for only 7 minutes. If these data are fitted to a linear regression, the results indicated the OP-TDLAS is approximately 40% greater than the concentrations measured with the OP-FTIR. The very limited number of measurements (n = 7) and the poor regression coefficient of determination (r 2 = 0.205) raise question as to the validity of the inter-comparison results. Although the instruments were deployed along an identical beam path, the difference in the concentrations measured with both instruments may be due to a difference in the height of the scanners, resulting in a difference in the height of the beam paths. The OP-FTIR scanner mount is higher than the OP-TDLAS scanner mount, resulting in the OP-FTIR optical beam path being higher than the OP-TDLAS beam path. The higher concentrations measured with the OP TDLAS may be due to the fact that the OP-TDLAS beam path was located closer to the surface of the landfill cell. The field team personnel have extensive experience with use of both OP FTIR and OP-TDLAS instruments and have observed and documented through other studies that the two instruments exhibit good comparability. (U.S. EPA, 2004; U. S. EPA, 2005a; U.S. EPA, 2005c; U.S. EPA, 2005e, U.S. EPA, 2005f. U. S. EPA, 2007). Immediately prior to this field study, Boreal Laser, Inc. performed a bench top calibration experiment with the OP-TDLAS instrument in a laboratory environment. The experiment consisted of inserting a known concentration of methane into a calibration cell, and comparing 5-4
the measured path-integrated methane concentration to the known path-integrated methane concentration in the calibration cell (9950 ppm-meter). Measurements were collected with the GasFinder OP-TDL instrument for approximately 3 minutes, and the results are shown in Figure 5-1. The average measured path-integrated concentration was 9,926 ppm meter, which yielded a percent error of -0.2%. The certificate of calibration is presented as an appendix to this report. Therefore, it was decided since the intercomparison results for these particular tests were not reliable, to report the results assuming that there was agreement based on previous experience. However, future tests should allow enough time to conduct intercomparison studies when two different types of optical instruments are in use. Figure 5-1. Results of the Methane Gasfinder Calibration Experiment 5.2.4 DQI Checks for Ambient Wind Speed and Wind Direction Measurements The meteorological head DQIs are checked annually as part of the routine calibration procedure. Before deployment to the field, the user is to verify the calibration date of the instrument by referencing the calibration sticker. If the date indicates the instrument is in need of calibration, the proper procedure is to return it to the APPCD Metrology Laboratory before deployment to the field. The precision and accuracy of the heads is assessed by conducting a post-deployment calibration in the EPA Metrology Lab using the exhaust from a bench top wind tunnel. This 5-5
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
Page 17 and 18:
This page intentionally left blank.
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.
Page 33 and 34:
2.2.3 Background Measurements Backg
Page 35 and 36: This page intentionally left blank.
Page 37 and 38: was aligned on the mirror targets i
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
Page 57 and 58: Table 3-17. Calculated Methane Flux
Page 63 and 64: 3.2.2 Bioreactor Cell 3.2.2.1 Febru
Page 69 and 70: Based on the calculations presented
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
Page 81 and 82: Monomethyl mercury concentrations i
Page 83 and 84: 5.1 Equipment Calibration Chapter 5
Page 85: The R 2 value was used to assess th
Page 89 and 90: 5.2.7 DQI Check of Total Mercury Sa
Page 91 and 92: Site #1 5.4 Site #2 77.9 Completene
Page 95 and 96: U.S. Environmental Protection Agenc
Page 97 and 98: d f e c b PDCs Y X a 2 12( y)( z) (
Page 99 and 100: When the VRPM configuration consist
Page 103 and 104: Table B-3. Distance, and Horizontal
Page 105 and 106: Table B-7. Distance, and Horizontal
Page 107 and 108: APPENDIX C Path-Averaged Methane Co
Page 109 and 110: Table C-3. Methane Concentrations (
Page 117 and 118: Table C-11. Methane Concentrations
show all

Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?