United States
Environmental Protection
Agency

Petroleum and Natural Gas Systems	&EFA

Monitoring Checklist for Underground
Natural Gas Storage

Final Rule: Mandatory Reporting of Greenhouse Gases (40 CFR Part 98)

What must be monitored?

If emissions are going to flares, need data elements under the source flare stacks (see

Monitoring Checklist for Onshore Petroleum and Natural Gas Production).

Record these parameters on an annual basis, unless specified otherwise.

1. Reciprocating Compressor Rod Packing Venting

Record emissions at each reciprocating compressor in as-found mode. Each
mode must be monitored at least once in any three consecutive calendar years.

Reciprocating Compressor Emissions in Operating Mode:

~	Rod packing venting from	~ Blowdown vent emissions from
reciprocating compressor in	reciprocating compressor in operational
operational mode (standard cubic	mode (standard cubic feet per hour)
feet per hour)

~	Total time the compressor is in	~ Annual throughput (million standard
operating mode (hours)	cubic feet per day)

~	Mole fraction of GHG in the vent
gas

Reciprocating Compressors Emissions in Standby Pressurized Mode:

~	Blowdown vent emissions from ~ Total time the reciprocating compressor is
reciprocating compressor in standby	in standby, pressurized mode (hours)
pressurized mode (standard cubic

feet)

~	Mole fraction of GHG in the vent
gas

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Underground Natural Gas Storage
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40 CFR 98, subpart W
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Reciprocating Compressors in Shutdown, Depressurized Mode:

~	Unit isolation valve emissions from ~ Total time the reciprocating compressor is
reciprocating compressor in	in shutdown, depressurized mode (hours)
shutdown depressurized mode

(standard cubic feet)

~	Mole fraction of GHG in the vent
gas

Record emission factors for recip

~	Total annual reciprocating	~
compressor emissions in operating
mode (cubic feet)

~	Total annual reciprocating	~
compressor emissions in shut down,
depressurized mode (cubic feet)

~	Total number of compressors	~
measured in standby, pressurized
mode

ing compressors in each mode.

Total annual reciprocating compressor
emissions in standby, pressurized mode
(cubic feet)

Total number of compressors measured in
operating mode

Total number of compressors measured in
shutdown, depressurized mode

~	Emission factor for rod packing ~
vent emission in operating mode
(cubic feet per hour)

~	Emission factor for blowdown vent ~
emissions in standby pressurized

mode (cubic feet per hour)

Emission factor for blowdown vent
emissions in operating mode (cubic feet
per hour)

Emission factor for isolation valve in
shutdown, depressurized mode (cubic feet
per hour)

Record emissions from each reciprocating compressor in all modes and total

annual emissions.

~	Total annual compressor emission ~
from all modes of operation
(standard cubic feet)

~	Total time the reciprocating	~
compressor is in standby,
pressurized mode in reporting year
(hours)

Total time the compressor is in operating
mode in reporting year (hours)

Total time the reciprocating compressor is
in shutdown, depressurized mode in
reporting year (hours)

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Underground Natural Gas Storage
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40 CFR 98, subpart W
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2. Centrifugal Compressor Venting

Record emissions at both wet and dry seal centrifugal compressors in as-
found mode. Each mode must be monitored at least once in any three

consecutive calendar years.

Centrifugal Compressor Emissions in Operating Mode, Wet and Dry Seal Compressors:

~	Wet seal oil degassing vents	~
emissions from centrifugal
compressor in operational mode
(standard cubic feet per hour)

~	Total time the centrifugal	~
compressor is in operating mode
(hours)

~	Type of meters used for making ~
measurements

~	Mole fraction of GHG in the vent ~
gas

Blowdown vent emissions centrifugal
compressor in operational mode (standard
cubic feet per hour)

Number of wet seals connected to the
degassing vent

Fraction of operating time vent gas is sent
to vapor recovery or fuel gas

Annual throughput (million standard
cubic feet per day)

Centrifugal Compressors in Not-operating, Depressurized Mode, Wet and Dry Seal
Compressors:

~	Unit isolation valve emissions from ~ Total time the centrifugal compressor is in
centrifugal compressor in shutdown	shutdown, depressurized mode (hours)
depressurized mode (standard cubic

feet)

~	Mole fraction of GHG in the vent
gas

Record emission factors for cent

~	Total annual emissions from all ~
centrifugal compressor in operating
mode (cubic feet)

~	Total number of centrifugal	~
compressors measured in operating

Petroleum and Natural Gas Monitoring Checklist

Underground Natural Gas Storage

Page 3 of 6

;al compressors in each mode.

Total annual emissions from all
centrifugal compressor in shut down,
depressurized mode (cubic feet)

Total number of centrifugal compressors
measured in shutdown, depressurized

40 CFR 98, subpart W
September 2010


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mode

mode

~	Emission factor for wet seal	~ Emission factor for blowdown vent
degassing vent in operating mode emissions in operating mode (cubic feet
(cubic feet per hour) per hour)

~	Emission factor for isolation valve
in shutdown, depressurized mode
(cubic feet per hour)

Record emissions from each centrifugal compressor in all modes and total

annual emissions.

~	Total annual centrifugal compressor ~ Total time the centrifugal compressor is in
emission from all modes of	operating mode in reporting year (hours)
operation (standard cubic feet)

~	Total time the centrifugal
compressor is in shutdown,
depressurized mode in reporting
year (hours)

3.	Natural Gas Pneumatic Device Venting

~	Actual and estimated counts of ~ Actual and estimated counts of
high bleed devices	intermittent bleed devices

~	Actual and estimated counts of low
bleed devices

4.	Connector Equipment Leaks Using Leak Detection at Storage Stations

~	Report CO2 emissions from all	~ Report CH4 emissions from all connectors
connectors (standard cubic feet) (standard cubic feet)

~	Operating time of leaking	~ Total number of components found leaking
component (hours)

5.	Valve Equipment Leaks Using Leak Detection at Storage Stations

~	Report CO2 emissions from all ~ Report CH4 emissions from all valves
valves (standard cubic feet)	(standard cubic feet)

~	Operating time of leaking	~ Total number of components found leaking
component (hours)

6.	Pressure Relief Valve Equipment Leaks Using Leak Detection at Storage Stations

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Underground Natural Gas Storage
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40 CFR 98, subpart W
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~	Report CO2 emissions from all ~ Report CH4 emissions from all pressure
pressure relief valves (standard	relief valves (standard cubic feet)
cubic feet)

~	Operating time of leaking	~ Total number of components found leaking
component (hours)

7.	Meter Equipment Leaks Using Leak Detection at Storage Stations

~	Report CO2 emissions from all ~ Report CH4 emissions from all meters
meters (standard cubic feet)	(standard cubic feet)

~	Operating time of leaking	~ Total number of components found leaking
component (hours)

8.	Open Ended Line Equipment Leaks Using Leak Detection at Storage Stations

~	Report CO2 emissions from all ~
open ended lines (standard cubic

feet)

~	Operating time of leaking	~
component (hours)

Report CH4 emissions from all open ended
lines (standard cubic feet)

Total number of components found leaking

Count and Factors at Storage Wellheads

Report CH4 emissions from all connectors

(standard cubic feet)

Total number of components

9. Connector Equipment Leaks Using Population

~	Report CO2 emissions from all ~
connectors (standard cubic feet)

~	Operating time of component	~
(hours)

10.	Valve Equipment Leaks Using Population Count and Factors at Storage Wellheads

~	Report CO2 emissions from all ~ Report CH4 emissions from all valves
valves (standard cubic feet)	(standard cubic feet)

~	Operating time of component	~ Total number of components
(hours)

11.	Pressure Relief Valve Equipment Leaks Using Population Count and Factors at Storage
Wellheads

~	Report CO2 emissions from all ~ Report CH4 emissions from all pressure
pressure relief valves (standard	relief valves (standard cubic feet)
cubic feet)

~	Operating time of component	~ Total number of components
(hours)

12. Open Ended Line Equipment Leaks Using Population Count and Factors at Storage

Wellheads

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Underground Natural Gas Storage
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40 CFR 98, subpart W
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Report CO2 emissions from all ~ Report CH4 emissions from all open ended

open ended lines (standard cubic	lines (standard cubic feet)

feet)

Operating time of component	~ Total number of components

(hours)

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Underground Natural Gas Storage
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40 CFR 98, subpart W
September 2010


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