Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

Environmental Protection Agency (EPA): Draft Guidance

Control Techniques Guideline for the Oil and Natural Gas Sector

RIN 2060-ZA22

General Comments

1) Reviewer recommends making any conforming changes to the CTGs that come about 

based on comments on the Oil and Gas NSPS rulemaking.

2) Reviewer recommends providing clarity in relation to how the CTGs and the voluntary

EPA programs are consistent and that companies that take voluntary actions that comply

with EPA’s programs will not be required to take additional action that would be counter 

to the voluntary program

3) Reviewer recommends that RACT technologies explicitly include flexibility to include 

technologies in addition to OGI—especially as new technologies emerge that provide 

similar or increased performance at reduced cost--e.g. infrared absorption based 

technologies, continuous monitoring systems, and unmanned sensing systems. Suggested 

language could be: “...OGI and other sufficiently tested monitoring technologies that 

demonstrate equivalency or superiority to the technical capabilities of current OGI 

technologies.” This language (or similar) should accompany all specifications of OGI 

technologies. 

4) Reviewer recommends that EPA should propose allowing flexibility to enable the use of 

continuous emissions monitoring systems and mass flow rate thresholds for compliance. 

Reviewer notes that a mass flow rate (scfh) is preferable to a concentration measurement 

(ppm), which is a less accurate measurement of leaks since it does not consider the impact 

of atmospheric conditions, such as wind or background methane. 

5) Reviewer recommends that EPA consider alternative approaches to conducting leak 

surveys that are more akin to approaches taken by Colorado and Wyoming. Concerns 

with the proposed approach include:

a. Many studies have shown a skewed distribution for emissions related to leaks and 

that the occurrence of such leaks is often random and difficult to predict, which 

suggests that more frequent surveys may be necessary to identify and repair the 

largest leaks. 

b. The proposed structure for determining the frequency of surveys may create a 

disincentive for companies to find leaks because not detecting a leak for two 

consecutive surveys would reduce the frequency (and costs) of future surveys.

Specific Comments

1) Reviewer recommends changing the assumed price for natural gas from $3.50/ mcf to 

$4.00/mcf in Table 4-3. A market price for natural gas of $3.5/mcf is inconsistent with 

the market price assumed on page 5-13 of this document and with the proposed NSPS, 

which assumes $4/mcf. 

2) Reviewer requests clarification regarding the following text on page 5-6:
Summary	of	Interagency	Working	Comments	on	Draft	Language	under	

EO12866/13563	Interagency	Review.		Subject	to	Further	Policy	Review.

“Although we have additional data available on fugitive emission from 

compressor stations, including data from the Measurement of Methane Emissions 

from Natural Gas Gathering Facilities and Processing Plants: Measurement 

Results study published in 20151, the data sets for gathering and boosting 

facilities had skewed distributions. In the study data set, 30 percent of gathering 

facilities contributed 80 percent of the total emissions, and gathering facilities 

emitted, on average, yielded higher emission than would be calculated with the 

factor used in this analysis. Therefore, for gathering and boosting station 

reciprocating compressors, we used the same methane emission factor used in the 

2011 NSPS TSD.”

Reviewer notes that the logic underlying this statement is unclear (there also seems to be 

grammatical problems with the second sentence). The text seems to be saying that recent 

research indicates that the distribution of emissions is skewed and greater than previously 

thought. Yet, a decision is made to use an emissions factor based on less current 

information. Is EPA trying to make the point that their estimated benefits of the rule are 

conservative? Please clarify.

 

1 Mitchell, Austin L. et al. Measurements of Methane Emissions from Natural Gas Gathering Facilities and 

Processing Plants: Measurement Results. Environ. Sci. Technol. 2015, 2119-3227.