&EPA

United States Environmental Protection Agency
Office of Enforcement and Compliance Assurance
Office of Criminal Enforcement, Forensics and Training

NEICVP1456E02

NEIC CIVIL INVESTIGATION REPORT
GMAP Region 6 Pollution Accountability Team FY2022

Calcasieu Parish, Louisiana
St. Charles Parish, Louisiana
St. James Parish, Louisiana
St. John the Baptist Parish, Louisiana

Investigation Dates:

April 11-23, 2022

NEIC Project Team:

Digitally signed by BRADLEY

BRADLEY VENNER VENNER

Date: 2022.08.02 20:06:26 -06'00'

Bradley Venner, Project Manager, NEIC

_	Digitally signed by DAVID

DAVID BRIGHT^®'

Date: 2022.08.03 07:56:08 -06W
Richard Helmich, Field Team Lead Investigator, NEIC

Authorized for Release by:

DCDCrr A	Digitally signed by REBECCA

nCDIlL.L.r\	connell

CONNELL

Rebecca Connell, Field Branch Chief, NEIC

Report Prepared for:
Steve Thompson
EPA Region 6
1201 Elm Street, Suite 500
Dallas, Texas 75270

iaffi

NATIONAL ENFORCEMENT INVESTIGATIONS CENTER
P.O. Box 25227
Building 25, Denver Federal Center
Denver, Colorado 80225

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CONTENTS

SUMMARY	3

METHODOLOGY	4

INSTRUMENTATION	4

CALIBRATION	4

DATA MANAGEMENT	5

QUALITY ASSURANCE	5

RESULTS	9

DISCUSSION	9

TABLES

Table 1. SUMMARY OF DAILY CALIBRATION VERIFICATION RESULTS	4

Table 2. COMPARISON OF ETO RESULTS FROM CRDS AND CANISTER ANALYSIS	7

FIGURE

Figure 1. EtO and VOC response, with overlay of VOC response on EtO response delayed by 12.5
seconds. Mapping ID: 220413_MA26	6

APPENDICES (NEIC-created*)

Appendix A KML Files (51 files)*

Appendix B Graphs of Calibration Results (4 pages)*

Appendix C EtO Quality Assurance Screening Results (3 pages)*

This Contents page shows all the sections contained in this report
and provides a clear indication of the end of this report.

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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SUMMARY

This report supplements U.S. Environmental Protection Agency (EPA) National Enforcement
Investigations Center (NEIC) report NEICVP1456E01 with additional data provided by the
Picarro G2920 cavity ring-down spectrometer (CRDS) instrument, which measured ethylene
oxide (EtO) and methane (CH4) concentrations, and maps developed from these measurements.
The CRDS was installed in NEIC's Geospatial Measurement of Air Pollution (GMAP) vehicle for
this investigation. These measurements were not provided in report NEICVP1456E01 because
results of laboratory analysis performed by Eastern Research Group (ERG) of canisters collected
during the GMAP survey were not yet available. These analytical results were necessary to
confirm EtO responses as measured by the CRDS. This report also describes additional steps
taken to validate these results. Report NEICVP1456E01 provides detailed information on the
events of the survey, which are not repeated in this report. Field measurements from the CRDS
were processed into files in Keyhole Markup Language (KML) format and are provided in
Appendix A.

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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METHODOLOGY

INSTRUMENTATION

The Picarro G2920 instrument can measure EtO, CH4, carbon dioxide, and water vapor. The
instrument was integrated into the other on-board GMAP instruments for the purposes of this
project by Richard Helmich and Ali Gitipour.

CALIBRATION

Calibration verifications for the CRDS were performed at the beginning and the end of each
working day. The gas cylinders used for calibration verification of EtO and CH4 were maintained
in a separate trailer. Corresponding calibration gases were metered from the cylinders through
a valved manifold. The calibration gases used for the CRDS were single-component calibration
mixtures of EtO and CH4. Detailed descriptions and certificates of analysis of the calibration
gases are in the project file. Calibration verifications also included analysis of a "ultra zero air"
that contains, at most, only very small quantities of any analyte.

Time periods during the calibration process when relatively constant zero gas and calibration
gas responses were obtained were visually identified by Bradley Venner. A summary of the daily
quantitative calibration results is shown in Table 1.

Table 1. SUMMARY OF DAILY CALIBRATION VERIFICATION RESULTS

Calibration
Level
(Span or
Zero)

Analyte

Unit

Calibration
Standard
Concentration

Average
Measured
Concentration
of Calibration
Events

Standard
Deviation
Between
Calibration
Events

Pooled Standard
Deviation Within
Calibration
Events

Span

EtO

parts per
billion (ppb)

105.4

65.2

0.7

0.4

Span

CH4

parts per
million
(ppm)

20.4

20.3

0.01

0.06

Zero

EtO

ppb

0

-0.1

0.1

0.3

Zero

CH4

ppm

0

0.0

0.0

0.0

The average calibration response of EtO was 65.2 ppb, and the stated value of the calibration
response was 105.4 ppb, so the average recovery of the calibration standard was 62%. This
response was stable; the variation in the average calibration response during the run was 0.7
ppb, a 1% relative standard deviation. This may imply that measurement results could be as
much as 162% higher than observed. Given the high precision of the instrument, this should be
considered an upper uncertainty bound on the measured results. Plots of the calibration results
used to calculate these values are shown in Appendix B.

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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During the calibration process, introducing or turning off the CH4 gas often resulted in an
intermittent EtO response. This response could be positive, negative, or oscillating. The CH4
concentration in the calibration gas was 20 ppm, and the Picarro G2920 instrument is stated to
be compatible with CH4 concentrations between 0 and 10 ppm, so this response may be an
artifact of the scale switching routine in the software. As shown by the calibration results after
the instrument completed the electronic scale adjustment, the concentration measured was
congruent with the certificated concentration. As discussed below, similar behavior was seen
when high CH4 concentrations were encountered in the field.

DATA MANAGEMENT

Following the completion of field activities, data files were processed by the custom application
software Google Earth Map Plotter, version 1.7. This software produces KML files that can be
opened using geographic information systems such as Google Earth Pro (GEP).

Fixed mapping scales were used for ChUand EtO. The minimum mapping scale (green) was set
at 2 ppm and 2 ppb for CH4 and EtO, respectively. The maximum mapping scale (red) was set at
4 ppm and 5 ppb for ChUand EtO, respectively. Values greater than maximum mapping scale
appear on the maps as proportionally taller red bars.

QUALITY ASSURANCE

All sampling and measurements, including GMAP measurements and the canister analysis
performed by ERG, that are described in this report are not within the scope of NEIC's ISO/I EC
17025 accreditation issued by the ANSI National Accreditation Board (certificate No. FT-0303).

During the data analysis process, a delay was observed in the response of the CRDS when
compared to the volatile organic compound (VOC) measurements. This delay could be detected
during the collection of some VOC measurements, where a very similar response could be
observed in the EtO measurements. The magnitude of the delay was roughly 13 seconds,
although there was some day-to-day variation of a second or two. The reason for the delay has
not been identified. The delay is unlikely to be due to the photo-ionization detector (PID)
instrument since it is located on the main sample trunk and an immediate response of the PID
instrument to calibration gases is observed.

An example of the delay is shown in Figure 1. This figure shows the measured EtO
concentrations by the CRDS and the measured VOC concentrations by the PID. It also shows
both responses on the same graph, normalized to their maximum values, but with the VOC
response delayed by 12.5 seconds.1 The maximum concentration for VOCs on this mapping run

1 VOC data for the GMAP survey are available in report NEICVP1456E01.

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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was 5,793 ppb, and the maximum concentration for EtO was 18.7 ppb. The qualitative
resemblance between the two responses is visually apparent, with multiple peaks matching
exactly and parallel behavior on several other peaks.

Figure 1. EtO and VOC response, with overlay of VOC response on EtO response delayed by 12.5 seconds.

Mapping ID: 220413_MA26

EtO

1.00-

0.00-

Time

variable
	 EtO

	 VOC

o
O

£? 0.50-
CQ

E
"cS
c
o
O

variable

	 EtO

	 VOC

15-
10-
5-

S °-

CL

| 6000-
° 5000-
4000-
3000-
2000-
1000-

14:20

14:26

VOC

14:22	14:24

Time

The delay introduces some uncertainty as to the wind conditions that prevailed at the time of a
recorded CRDS reading. This report presents maps that correlate the wind speed and direction
recorded at time t, with the CRDS reading recorded at time t + d, where d is the duration of the
delay. To create these maps, modified data files were prepared by projecting the CRDS readings
and a row identifier into a separate data table, subtracting 13 from the row identifier, and then
merging the separate data table into the original file using the row identifier. Since instrumental
responses are recorded roughly every second, this approach corresponds to a 13-second delay
but avoids the complexity of the approximate merge that would be required by using the

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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recorded time value. Although this procedure means that the exact value of the delay can vary
from map to map, this variation should be less than 1 second. Maps prepared using this
method should be interpreted with some caution, particularly when wind directions are highly
variable, and the exact value of the delay can impact the attributed wind speed and direction.

Another data quality concern is the potential that the observed EtO response was not specific
to EtO but could be the result of an interferent. This survey involved some near-field
measurements of relatively high VOC concentrations (e.g., at the parts per million level) while
measuring EtO at low concentrations (e.g., at the parts per billion level). An example of this
type of situation is illustrated in Figure 1, where the observed VOC concentrations were much
higher than the observed EtO concentrations. Although the observed correlation does not
prove that there was an interference, this potential must be recognized.

An important measure of the specificity of the CRDS measurement can be obtained by
comparing the EtO concentration measured in the canister to the average EtO concentration
measured by the CRDS during the canister sampling time. The average EtO concentration was
calculated both with and without the delay. The results of this comparison are shown in Table
2.

Table 2. COMPARISON OF ETO RESULTS FROM CRDS AND CANISTER ANALYSIS

CanisterJD

MapJD

EtO, ppb
(CRDS, no delay)

EtO, ppb
(CRDS, with delay)

EtO, ppb
(Canister)

3071

220411_MA10

<2

<2

0.09

10027

220411_MA14

<2

<2

0.08

3101

220411_MA28

<2

<2

0.04

3068

220411_MA35

<2

<2

0.04

4612

220412_MA01

<2

<2

0.15

521

220412_MA24

<2

<2

0.05

3116

220412_MA41

<2

<2

0.04

9497

220412_MA47

<2

<2

0.11

4621

220413_MA12

<2

<2

0.57

4609

220413_MA16

3.6

3.3

5.39

4605

220414_MA36

<2

<2

0.07

10007

220414_MA42

<2

<2

0.06

10009

220415_MA03

<2

<2

0.07

9490

220415_MA07

<2

<2

0.06

3066

220416_MA24

5.5

5.3

5.13

4606

220418_MA13

3.3

<2

1.59

527

220418_MA54

<2

<2

0.06

535

220418_MA56

<2

<2

0.06

278

220419_MA17

12.5

13.1

19

10018

220419_MA23

5.9

5.2

10.4

118

220419_MA35

7

6.4

8.62

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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Table 2. COMPARISON OF ETO RESULTS FROM CRDS AND CANISTER ANALYSIS

CanisterJD

MapJD

EtO, ppb
(CRDS, no delay)

EtO, ppb
(CRDS, with delay)

EtO, ppb
(Canister)

4602

220420_MA08

<2

<2

0.22

3073

220421_MA32

<2

<2

0.14

4618

220421_MA37

<2

<2

0.33

279

220421_MA39

<2

<2

ND

4601

220421_MA54

<2

<2

0.25

10008

220422_MA11

<2

<2

0.08

519

220422_MA18

<2

<2

ND

The EtO response also depends upon the CH4 response of the instrument. The Picarro G2920
instrument is only stated to be consistent with CH4 concentrations between 0 and 10 ppm. On
several occasions during field measurements, CH4 concentrations higher than 10 ppm were
observed, and these resulted in an EtO response, which could be positive, negative, or
oscillating. A similar phenomenon was observed during instrument calibration, when negative
EtO values were sometimes observed at the same time as a change in the CH4 calibration gas
flow (on or off).

Therefore, a quality assurance screen was conducted on each mapping ID for which the average
EtO response was greater than 3 ppb. Maps were excluded from this report when CH4
concentrations were outside the recommended range or had strong correlations with VOCs and
for which there were no known EtO sources.

KML files were included for each mapping run that passed the quality assurance screening
process. The resulting KML files are provided electronically as Appendix A. The results of the
quality screen are provided in Appendix C.

The GMAP AirMar instrument (wind speed and direction sensor) failed to provide wind speed
and direction data on several occasions. The most severe outages occurred on April 11, 2022,
and April 22, 2022, when approximately 50% and 0%, respectively, of the wind speed and
direction data were recorded. However, most survey days had at least one partial outage.
During malfunction events, source attribution can be more challenging. Wind speed and
direction data from the National Weather Service at nearby locations can be examined in the
absence of data from the AirMar.2

2 https://www.weather.gov/help-past-weather, accessed May 16, 2022.

Page 8 of 9

NEICVP1456E02

GMAP R6 PAT FY22, Louisiana

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RESULTS

GMAP field measurement activities were conducted on 12 days during the investigation period.
Detailed information of GMAP activities, indexed by mapping run, are provided in report
NEICVP1456E01.

DISCUSSION

GMAP data are best used to screen for areas where further investigation using more traditional
inspection and leak detection instruments can help to determine if emissions meet regulatory
requirements.

Wind direction provides an important, but not infallible, source of information on the direction
of potential emissions sources. For example, when the wind direction is changing frequently, a
measured concentration may also be from an emitted plume that has been blown back to the
source. Large obstructions such as tanks also have wakes that can generate local winds
opposite of the prevailing wind direction. Additionally, the AirMar is located on top of the
moving vehicle and can be affected by the vehicle slipstream at higher speeds. To avoid issues
with vehicle slipstream causing erroneous wind data, the data is only recorded when the
vehicle's speed is less than 25 miles per hour. The wind direction is determined with an internal
magnetic compass that also may be affected by local magnetic fields and large, nearby metallic
objects.

NEICVP1456E02

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GMAP R6 PAT FY22, Louisiana

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Appendix A
KML Files

VP1456E02

GMAP Region 6 Pollution Accountability Team FY2022
Calcasieu Parish, Louisiana
St. Charles Parish, Louisiana
St. James Parish, Louisiana
St. John the Baptist Parish, Louisiana

Please see folder sent with project report for digital KML files.

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Appendix B
Graphs of Calibration Results

VP1456E02

GMAP R6 Pollution Accountability Team FY2022
Calcasieu Parish, Louisiana
St. Charles Parish, Louisiana
St. James Parish, Louisiana
St. John the Baptist Parish, Louisiana

4 pages

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Figure 1: Ultra-zero gas data and mapping scales, EtO

X

w
w

0)

o
o

dI

+

Cone	°

ProcessMin	°

Quant	°

ProcessMax	0

0 10203040 5060

0 102030405060

0 102030 405060

3-

2'
1"

o-

-1"

3

2

1"

0"

-1-

220421 CA01

220421 CA02

220422 CA01

220422 CA02

220423 CA01

220423 CA02





























Aa

>JWwv>mr+/\hs-





220418 CA01

220418 CA02

220419 CA01

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220414 CA01

220414 CA02

220415 CA01

220415 CA03

220416 CA01

220416 CA02



































W/V

220411 CA01

220411 CA02

220412 CA01

220412 CA02

220413 CA01

220413 CA02



























vWW









3
2
" 1

-	0

-	-1

" 3

2
1

" 0
- -1

0 1 020 3040 50 60

0 10 2030405060

Row.lndex

0 102030405060

NEICVP1456E02

Appendix B
Page 1 of 4

GMAP R6 PAT FY22, Louisiana

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Figure 2: Ultra-zero gas data and mapping scales, CH4

X

w
w

O)

o
o

dI

+

220421 CAP 1220421 CA02 220422 CAP 1220422 CA02 220423 CAP 1220423 CA02

220418 CA01

CHi:

cm

0:11
CMH

0i):
0:
0:
0i)i

Cone	°

ProcessMin °

Quant	°

ProcessMax 0

0 102030405060 0 102030405060 0 102030405060
						

220418 CA02220419 CA01



220414 CA01



220411 CA01

i\2-

<11-

I I I I I I I





i i i i i i i

220419 CA02

220414 CA02220415 CA01



220411 CA02220412 CA01



m—i i i i i

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i i i i i i i



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220416 CA01

220413 CA01

i i i i i i i

220416 CA02

220413 CA02



I I I I I I I

0 102030405060

0 102030405060

Row.lndex

0 102030405060

NEICVP1456E02

Appendix B
Page 2 of 4

GMAP R6 PAT FY22, Louisiana

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Figure 3: Calibration gas data and mapping scales, EtO

X

w
w

0)

o
o

dI

+

74
72
70
68
66
64

74
72
76
68
66
6 A

0 102030405060
			

220421 CA01

220418 CA01



220414 CA01

220411 CA01

i i i i i i i

220421 CA02

220422 CA01



220418 CA02

220419 CA01

220414 CA02

220411 CA02



I I I I I I I

Cone	°

ProcessMin	°

Quant	°

ProcessMax	0

0 102030405060
			



220415 CA01

220412 CA01

i i i i i i i

220422 CA02



220419 CA02

220415 CA03

220412 CA02

i i i i i i—r

0 102030405060
I'll.	

220423 CA01

220423 CA02

220420 CA01

220420 CA02

220416 CA01

220413 CA01

l—i i i i i i

220416 CA02

220413 CA02

i i i i i i i

0 102030405060

0 102030405060

Row.lndex

0 102030405060

NEICVP1456E02

Appendix B
Page 3 of 4

GMAP R6 PAT FY22, Louisiana

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Figure 4: Calibration gas data and mapping scales, CH4

X
CO

W

w

0)

o
o

dI

+

Cone	0

ProcessMin	0

Quant	0

ProcessMax	0

0 102030405060

0 102030405060

0 102030405060

2+

2t
20
20

2t
21-
20
20

220421 CA01

220421 CA02

220422 CA01

220422 CA02

220423 CA01

220423 CA02





































220418 CA01

220418 CA02

220419 CA01

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220414 CA02

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A.







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220412 CA02

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5
o















I







n











11111n11111n11111n11111n11111n11111r

0 102030405060	0 102030405060	0 102030405060

Row.lndex

NEICVP1456E02

Appendix B
Page 4 of 4

GMAP R6 PAT FY22, Louisiana

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Appendix C
EtO Quality Assurance Screening Results

VP1456E02

GMAP Region 6 Pollution Accountability Team FY2022
Calcasieu Parish, Louisiana
St. Charles Parish, Louisiana
St. James Parish, Louisiana
St. John the Baptist Parish, Louisiana

3 pages

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M.-n:- ID

t;o (n |=.">)

CH4 Ipp^O

IVUip

Notes

220411_MA09

8.3

11.5

No

Single large EtO negative spike at -7500 ppb

220411_MA13

3.5

2.7

Yes

No clear relation with VOC or CH4

220411_MA14

5.3

4.1

No

Parallel with VOC

220411_MA15

3.3

2.7

No

Below quant; no clear relation with VOC or CH4

220411_MA24

4.5

5.6

No

CH4 greater than 5 ppm; EtO spikes correspond with
CH4 peaks

220411_MA35

14.1

2.1

No

Strong correlation with VOC

220412_MA01

8575.3

2.0

No

Peaked VOC plus CH4 goes to zero

220412_MA02

10.5

2.6

No

Strong correlation with VOC but only a single peak

220412_MA08

3.2

2.0

No

Below quant; no clear relation with VOC or CH4

220413_MA04

5.8

2.1

Yes

No clear relation with VOC or CH4

220413_MA08

3.5

2.0

No

Below quant; no clear relation with VOC or CH4

220413_MA09

4.1

2.0

No

Averaged 1 meter bin below quant; ORD canister; No
clear relationship with VOC or CH4

220413_MA13

5.0

1.9

Yes

No clear relation with VOC or CH4

220413_MA16

25.0

2.7

Yes

Confirmed by ERG canister

220413_MA24

3.9

5.5

No

Large negative EtO value

220413_MA26

18.7

2.0

No

Parallel with large VOC value

220413_MA27

15.8

1.9

No

Parallel with large VOC value

220413_MA28

13.5

1.9

No

Parallel with large VOC value

220413_MA29

14.5

1.9

No

Parallel with large VOC value

220413_MA30

12.8

2.0

No

Parallel with large VOC value

220413_MA31

15.5

1.9

No

Parallel with large VOC value

220413_MA37

15.7

2.2

No

Parallel with large VOC value

220413_MA38

12.4

2.1

No

Parallel with large VOC value

220413_MA41

11.1

6.6

No

Methane-related spike

220413_MA42

24843.4



No

Methane-related spike

220413_MA43

824.0

7.9

No

Methane-related spike

220413_MA45

13.3

2.3

Possible

No clear relation with VOC or CH4

220413_MA46

4.7

2.0

No

Parallel with large VOC value

220413_MA47

11.2

8.0

Possible

Early hit on EtO followed by methane-related spike

220413_MA48

65.5

2.3

No

Methane-related spike

220413_MA49

13.3

1.9

No

Parallel with VOC value

220413_MA50

22.4

2.0

No

Parallel with VOC value

220413_MA51

16.8

481.8

No

Methane-related spike

220414_MA06

3.0

440.6

No

Methane-related spike

220415_MA35

4.0

2.0

Possible

Brief peak but unrelated to CH4 or VOC

220416_MA23

3.5

2.3

Possible

Brief peak but unrelated to CH4 or VOC

220416_MA24

10.4

2.0

Yes

Confirmed by ERG canister

220416_MA25

7.2

1.9

Yes

Unrelated to CH4 & VOC, vicinity of previous canister

220416_MA27

7.2

1.9

Possible

Peak occurs near peak VOC value but not exact parallel

220416 MA28

3.2

1.9

Possible

Barely over background but unrelated

NEICVP1456E02

Appendix C
Page 1 of 3

GMAP R6 Louisiana, FY2022

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M.-n:- ID

t;o (n |=.">)

CH4 Ipp^O

IVUip

Notes

220418_MA04

5.0

2.1

Possible

Unrelated to CH4 & VOC

220418_MA05

53.4

2.0

No

Parallel to VOC

220418_MA07

11.9

2.1

Possible

Unrelated to CH4 & VOC

220418_MA13

29.1

2.0

No

Parallel to VOC

220418 MA63

3.5

2.1

Possible

Brief peak but unrelated to CH4 or VOC

220418 MA68

30.4

2.2

Possible

Somewhat related to VOC but not exact

220418 MA69

8.6

2.1

Possible

Unrelated to CH4 & VOC

220418_MA70

13.5

2.0

Possible

Continued from previous result, unrelated to CH4 and
VOC

220418_MA71

10.4

2.0

Possible

Unrelated to CH4 & VOC

220418_MA72

17.0

2.1

Possible

Somewhat related to VOC but not exact

220418_MA73

10.6

2.1

Possible

Somewhat related to VOC but not exact

220419_MA04

9.8

10.6

No

Large negative EtO value

220419_MA09

10.2

2.0

Possible

Unrelated to CH4 & VOC

220419_MA17

23.3

2.1

Possible

Somewhat related to VOC but not exact

220419_MA18

20.4

2.0

Yes

Unrelated to CH4 & VOC

220419_MA19

20.2

2.0

Yes

Unrelated to CH4 & VOC

220419_MA20

12.5

2.1

Possible

Somewhat related to VOC but not exact

220419_MA22

12.0

2.2

Possible

Somewhat related to CH4 but not exact, unrelated to
VOC

220419_MA23

16.1

2.2

Yes

Confirmed by ERG canister

220419_MA24

7.2

2.1

Possible

Unrelated to CH4 & VOC

220419_MA26

11.5

2.0

Possible

Unrelated to CH4 & VOC

220419_MA31

4.7

2.4

Possible

Unrelated to CH4 & VOC

220419_MA33

21.9

2.1

No

Parallel to VOC

220419_MA34

12.1

2.1

Possible

Somewhat related to VOC but not exact

220419_MA35

16.4

2.1

Yes

Confirmed by ERG canister

220419_MA36

15.2

2.1

Possible

Somewhat related to VOC but not exact

220419_MA44

5.0

2.4

Possible

Unrelated to CH4 & VOC

220420_MA03

10.0

4.1

Possible

Somewhat related to VOC but not exact

220420_MA04

5.9

2.5

Possible

Somewhat related to CH4 but not exact, unrelated to
VOC

220420_MA10

3.6

2.8

Possible

Somewhat related to CH4 but not exact, unrelated to
VOC

220420_MA12

3.2

2.9

Possible

Barely over background but unrelated

220420_MA15

9.9

2.3

Possible

Unrelated to CH4 & VOC

220420_MA16

13.6

2.0

Possible

Parallel with VOC but may be co-generated

220420_MA17

13.4

2.1

Possible

Late rise in value prior to end of mapping run

220420_MA18

66.6

6.0

Possible

Somewhat related to VOC but not exact

220420_MA19

7.4

3.3

Possible

Somewhat related to VOC but not exact

220420_MA20

18.2

5.3

Possible

Closely related to VOC but not exact

220420_MA24

6.6

2.4

Possible

Unrelated to CH4 & VOC

220420 MA26

5.6

2.4

Possible

Unrelated to CH4 & VOC

220420_MA27

4.4

2.3

Possible

Looks like drift

220420 MA28

11.0

2.0

Possible

Unrelated to VOC, related to CH4 but at very low levels
of CH4

NEICVP1456E02

Appendix C
Page 2 of 3

GMAP R6 Louisiana, FY2022

-------
Map_ID

EtO (ppb)

CH4 (ppm)

Map

Notes

220420_MA29

7.4

2.0

No

Map duration is too short

220420_MA30

9.6

2.5

Possible

Unrelated to CH4 & VOC

220420_MA31

10.1

2.4

Possible

Closely related to CH4 but not exact

220421_MA32

7.6

356.9

No

Sharp spike in CH4

220421_MA42

3169.2

25.2

No

CH4 greater than 25 ppm

220421_MA43

11940.7

596.9

No

CH4 greater than 400 ppm; EtO spikes at the same time

220421_MA44

643.9

531.8

No

CH4 greater than 400 ppm; EtO spikes at the same time

220421_MA45

3442.5

14.0

No

CH4 greater than 10 ppm

220421_MA47

3903.5

661.4

No

CH4 greater than 600 ppm; EtO spikes correspond with
CH4 peaks

220422 MA25

136.8

16.5

No

CH4 greater than 15 ppm; EtO spikes correspond with
CH4 peaks

NEICVP1456E02

Appendix C
Page 3 of 3

GMAP R6 Louisiana, FY2022

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