### 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**Environmental Protection Agency (EPA): Draft Guidance**  **Control Techniques Guideline for the Oil and Natural Gas Sector**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 an y 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 additio nal 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

— especiall y as new technologies emerge that provide similar or increased performan ce at reduced cost

-- e.g. infrared absorption based technologies, continuous monitoring sy stems, and unmanned sensing s ys tems. Suggested language could be: “...OGI and other sufficientl y tested monitoring technologies that demonstrate equivalency

or superior ity

to the technical capabilities of current OGI technologies.” This language (or similar) should accompan y all specifications of OGI technologies. 4) Reviewer recommends that EPA should propose allowing flexibility to enable the use of continuous emission s monitoring s ys tems 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 leak s since it does not consider the impact of atmos pheric conditions, such as wind or background methane. 5) Reviewer recommends that EPA consider alternative approaches to conducting leak survey s that are more akin to approaches taken b y Colorado and Wy oming. 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 survey s may be necessary

to identify

and repair the largest leaks. b. The proposed structure for determining the frequency of survey s may

create a disincentive for companies to find leaks because not detecting a leak for two consecutive survey s would reduce the frequency (and costs) of future survey s. **Specific Comments**
1) Rev iewer 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 Ga s Gathering Facilities and Processing Plants: Measurement Results study published in 2015 1 , 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 th e 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 emiss ion factor used in the 2011 NSPS TSD.” Reviewer notes that the logic underl yi ng this statement is unclear (there also seems to be grammatical problems with the second sentence). The text seems to be say ing that recent research indicates that the distributi on of emissions is skewed and greater than previousl y thought. Yet, a decision is made to use an emissions factor based on less current information. I s EPA trying to make the point that their estimated benefits of the rule are conservative? Please clari fy

.

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.