Quantifying Uncontrolled Landfill Gas Emissions from Two Florida ...

southern and eastern planes (28 g/s), is a negative value. This is most likely due to the fact that
the methane flux values measured along the northern and western VRPM planes (14 and 2.8
grams per second, respectively) represent slight underestimations of the actual fluxes. The
prevailing winds during the time of the measurements were from the southeast, directly towards
the location of the OP-FTIR instrument, or convergence of the optical beams used in the OP­
FTIR measurements (see Figure 2-4). Flux values calculated with the VRPM method during
these conditions often result in an underestimation of the flux values. Based on this information,
the methane flux value from the top of the landfill cell is estimated to be negligible. This
conclusion is supported by the results of the ORS measurements collected in the control cell on
February 25, which are presented in section 3.2.1.2.
The sum of the flux values measured along the southern and eastern planes, 28 grams per second,
represents the calculated methane flux value from the southern and eastern slopes of the landfill
cell.
Tables 3-16, 3-17, 3-18, and 3-19 present the calculated methane flux, measurement time,
prevailing wind speed, and prevailing wind direction during the time of the VRPM
measurements along the northern, eastern, southern, and western VRPM configurations,
respectively. The measurement time shown represents the midpoint of the averaging period,
which lasts approximately 15 minutes.
Table 3-16. Calculated Methane Flux and Prevailing Wind Speed and Direction
Measured on February 24 along the Northern VRPM Configuration in the
Control Cell of Site #2
Time
Methane Flux
(g/s)
Prevailing Wind Direction
(degrees from North)
Prevailing Wind Speed
(m/s)
15:11:22 8.2 127 5.1
15:18:21 11 136 6.2
15:24:51 19 147 7.6
15:31:52 21 153 7.6
15:38:52 17 151 7.1
15:45:51 18 153 7.1
15:52:52 15 147 6.2
15:59:52 15 144 6.6
16:06:51 14 148 6.2
16:13:22 12 144 5.7
16:20:22 14 143 6.3
16:26:52 14 139 6.7
16:33:51 17 142 7.2
16:40:52 14 135 5.3
16:47:52 12 132 5.8
16:54:51 11 130 5.7
17:01:52 9.8
Average= 14
Standard Dev.=3.43
131 6.1
3-21