EPA RESPONSE TO

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

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Environmental Protection Agency (EPA): Proposed Rule

Oil and Natural Gas Sector: Emission Standards for New and Modified Sources

RIN 2060-AS30

General Comments:

1. Reviewer recommends providing additional discussion on why it is necessary to regulate 

methane in the areas where controls for VOCs are already providing the reduction.

EPA RESPONSE: 

We believe the preamble fully supports across the category regulation of VOC and 

methane. “Based on the EPA’s analysis (see section VIII), we believe it is important to 

regulate methane from the oil and gas sources already regulated for VOC emissions to 

provide more consistency across the category, and that the best system of emission 

reduction (BSER) for methane for all these sources is the same as the BSER for VOC. 

Accordingly, the current VOC standards also reflect the BSER for methane reduction for 

the same emission sources. In addition, with respect to equipment used category-wide of 

which only a subset of those equipment are covered under the NSPS VOC standards (i.e., 

pneumatic controllers and compressors located other than at well sites), EPA’s analysis 

shows that the BSER for reducing VOC from the remaining unregulated equipment to be 

the same as the BSER for those currently regulated. The EPA is therefore proposing to 

extend the current VOC standards for these equipment to the remaining unregulated 

equipment.”

2. Reviewer recommends considering the overall economic impact on stripper wells and 

ensuring that any proposed NSPS requirements are not overly burdensome such that 

stripper wells would need to be shut down based on any single or combination of 

proposed requirements.

EPA RESPONSE: 

Please see additional discussion in the preamble. “We do not intend to subject low 

production wells (i.e., those with an average daily production of 15 barrel equivalents or 

less) to the standards for well completion. It is our understanding that drilling of a low 

production well is infrequent and in most instances unintentional, but production may 

nevertheless proceed due to economic reasons. While we have learned that a daily 

average of 15 barrel equivalents is representative of low production wells, we solicit 

comment on the appropriateness of this threshold for applying the standards for well 

completions. We further solicit comment on the air emissions associated with low 

production wells, and the characteristics of low production wells that may inform owners 

or operators and enforcement personnel in advance of production whether such a well 

would be a low production well, so we may evaluate the feasibility of an exemption from 

well completion standards.”
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Summary of Interagency Working Comments on Draft Language under 

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

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Well Completions:

1. Reviewer recommends considering other factors such as geographic location, gas 

production and GOR of nearby wells, length of hydraulic fracturing, and well depth to 

sub-categorize units to maximize cost-effectiveness and not unduly burden units.

EPA RESPONSE: 

We are taking comment on this in Section VIII.F “We solicit comment on the types of oil 

wells that will not be capable of performing a REC or combusting completion emissions 

due to technical considerations such as low pressure or low gas content, or other physical 

characteristics such as location, well depth, length of hydraulic fracturing, or drilling 

direction (e.g., horizontal, vertical, directional).”

Further, we are proposing a GOR threshold of 300 scf/barrel for applicability of well 

completion requirements. We understand that it is important for operators to know the 

affected facility status of a well completion prior to commencement of the completion 

operation and are soliciting comment whether GOR of nearby wells is a reliable indicator

that could be used by operators. 

2. Reviewer recommends not regulating oil wells for which gas recovers would be too small 

(e.g., yielding less than 30 tons).

EPA RESPONSE: 

We are taking comment on this in Section VIII.F. Please see response to previous 

question. The purpose of the proposed GOR threshold is to identify and exclude wells 

that would have very small magnitudes of gas production and potential emissions.

3. Reviewer recommends considering the following thresholds:

a. physical characteristics of certain oil wells that make REC and/or combustion not 

technically feasible or economic;

b. all vertical oil wells as the nature of the wells make it difficult or technically 

infeasible to operate a two or three phase gas/liquid separator because these wells 

generally lack sufficient wellhead pressure or a sufficient quantity of gas; and/or

c. low pressure or low volume wells and heavy oil wells based on the GOR. Low 

pressure wells could be based on a threshold sales line/gathering line or a wate 

gradient formula.

EPA RESPONSE: 

We are taking comment on this in Section VIII.F. 

Pneumatic Controllers:

1. Reviewer recommends removing any recordkeeping requirements for low-bleed or 

zero-bleed pneumatic controllers as it is unnecessary and burdensome.
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Summary of Interagency Working Comments on Draft Language under 

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EPA RESPONSE: 

In locations other than natural gas processing plants, low-bleed and zero-bleed pneumatic 

controllers are not affected facilities, and thus no recordkeeping or reporting requirements 

apply to this equipment. However, natural gas-operated pneumatic controllers located at 

natural gas processing plants are affected facilities regardless of their bleed rate. In such 

cases, this equipment is subject to the recordkeeping and reporting requirements outlined 

in §60.5420a. Such records would include justification of the need for a device with a 

natural gas bleed rate greater than zero.

Compressors:

1. Reviewer recommends explaining how the National Inventory based on Subpart W data 

was considered within the development of the proposed rule. Specifically, as the more 

recent data appears to provide lower emission data, how has EPA taken that into 

consideration when developing the proposed rule?

EPA RESPONSE: 

Detailed information on data used in the development of the proposed rule, and a 

discussion of data from alternative and newly available data sources, is included in the 

TSD.

For most sources, emissions and activity data from the 2014 U.S. GHG Inventory 

(GHGI) were used in the development of the proposed rule. While overall sector-level 

emissions decreased in the 2015 GHGI compared to the 2014 GHGI (primarily due to 

revisions to offshore production estimates), emissions and activity data for the sources 

included in this proposal did not change significantly. The most recent facility-level 

GHGRP data was also reviewed in the development of the proposed rule. The GHGRP 

data indicate higher emissions than in the GHGI for some sources and indicate lower 

emissions for others, as is discussed in the TSD.

As EPA continues to review new data sources, including key activity data from the 

GHGRP which will become available in the fall of 2015, EPA will consider how these 

data may be used to update its GHG inventory estimates and analyses related to this 

rulemaking. EPA has for several sources updated the GHGI to use GHGRP data and will 

continue to do so as additional key data become available. 

2. Reviewer recommends removing the requirement for vapor recovery units for wet-seal 

centrifugal compressors as there are potential issues related to feasibility and safety. 

EPA RESPONSE: 

The proposed NSPS does not require vapor recovery units for control of emissions from 

wet-seal centrifugal compressors; the rule requires 95 percent control of these emissions

or routing of the emissions to a process. Under section 111, the EPA cannot dictate what 
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type of control device is required to meet an emission standard. That decision is made by 

the owner or operator. The NSPS does include, however, requirements for specific types 

of control devices, if such devices are used to meet the emission standard (e.g., cover and 

closed vent system requirements and requirements for periodic monitoring). As is the 

case across the NSPS, a control technique is not considered BSER if technical feasibility 

or safety issues are a concern.

3. Reviewer recommends providing additional explanation how EPA ensured that emissions 

from rod packing leaks are separated from fugitive emissions from compressors. 

EPA RESPONSE: 

Fugitive emissions do not include gas that is vented from a device (e.g., pneumatic 

controller exhaust port, reciprocating compressor rod packing). As a result, fugitives seen 

in the rod packing area would likely not be from a fugitive emissions component since, 

given the structure of reciprocating compressors, it is unlikely to have valves, flanges, 

etc. located in the immediate area of the rod packing.

Pneumatic Pumps:

1. Reviewer recommends excluding diaphragm pumps, glycol pumps, and all low volume 

chemical injection pumps or other pumps that are used intermittently below a fixed 

number of hours/year. 

EPA RESPONSE: 

Glycol (i.e., “Kimray”) pumps are not covered by the proposed NSPS. With regard to an 

operating hour threshold, we would need additional data (such as emissions levels 

associated with different operating times and costs) to fully evaluate this potential option. 

Fugitive Emissions:

1. Reviewer recommends considering additional options besides OGI and Method 21, 

specifically AVO methods. The relative benefits and costs should be included within the 

discussion.

EPA RESPONSE: 

We are requesting comment on whether there are other fugitive emission detection 

technologies that provide an equivalent or greater level of detection than OGI technology 

or EPA Method 21 that should be allowed in VIII.F. 

2. Reviewer recommends providing clarification for the repair costs within the RIA and 

TSD for Method 21 and OGI. It is unclear why the repair costs change within OGI to the 

extent that they do and why they differ from Method 21. 
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EPA RESPONSE: 

Please see clarification in section VIII.G, “While the costs for repairing components that 

are found to have fugitive emissions during a fugitive monitoring survey remain the 

same, the annual repair costs will differ based on monitoring frequency”. Section 5.4 of 

the TSD provides additional repair cost information. 

3. Reviewer recommends providing clarification for why the emission reduction estimates 

deviate from the Colorado source document and how it was used within the RIA.

EPA RESPONSE: 

The preamble states that information in the white paper related to the potential emission 

reductions from the implementation of an OGI monitoring program varied from 40 to 99 

percent. The causes for this range in reduction efficiency were the frequency of surveys 

performed and different assumptions made by the study authors. We used engineering 

judgment to identify anticipated percent reduction based on frequency. We believe that 

40%, 60%, and 80% are adequately representative of the reduction we would expect with 

increased frequencies of survey. 

4. Reviewer recommends providing additional information on the Method 21 emission 

reduction information. It is unclear within the TSD how the differences between the 

Method 21 for 10,000 ppm leaks and Method 21 for 5,000 ppm leaks were determined 

(see Table 5-20 on page 98). 

EPA RESPONSE: 

Please see clarifying text in Section VIII.G, and Section 5.4 of the TSD. “In our analysis, 

we estimated emissions reductions for annual, semiannual and quarterly options for 

conducting the Method 21 monitoring at the three repair threshold levels of 500 ppm, 

2,500 ppm and 10,000 ppm. The EPA Equipment Leaks Protocol document provides 

emissions factor data based on leak definition and monitoring frequencies primarily for 

the Synthetic Organic Chemical Manufacturing Industry (SOCMI) and Petroleum 

Refining Industry. This data was used to estimate the uncontrolled emissions (i.e., 

baseline emissions and the corresponding emission reduction percentages that could 

potentially be achieved for each of the leak definitions (500 ppm, 2,500 ppm, 10,000 

ppm) and monitoring frequencies (annual, semiannual, quarterly). Using this information 

we calculated an expected emissions reduction percentage for each of the combinations 

of monitoring frequency and repair threshold.”

5. Reviewer recommends providing additional discussion on whether observed leak rate 

would change over successive surveys, and if so, account for that within the analysis.

EPA RESPONSE: 

EPA will provide this additional context in the technical support document.
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6. Reviewer recommends phasing in fugitive emissions requirements with larger sources in 

the first year and smaller sources in the following years. Small firs should also be 

provided 180 days instead of 30 days after well completion.

EPA RESPONSE:

We are soliciting comment on whether 30 days is an appropriate period for the first 

survey following startup or modification.

7. Reviewer recommends co-proposing OGI and Method 21 as BSER or proposing Method 

21 as BSER and allowing OGI as an acceptable compliance mechanism. 

EPA RESPONSE:

Our BSER analysis is detailed in Section VIII.G, and OGI with semiannual monitoring 

remains BSER. However, we are taking comment on allowances for use of Method 21 in 

certain circumstances. “As explained above, Method 21 is not as cost-effective as OGI. 

That said, there may be reasons why and owner and operator may prefer to use Method 

21 over OGI, either for monitoring surveys or re-survey to assure proper repair. For 

example even though we envision repairs and resurveys to occur during the monitoring 

survey, there may be components that cannot be immediately repaired and require 

additional time for such repairs thus requiring the resurveying at a later time. In such 

situations, an owner and operator may prefer to use Method 21 for resurvey if it is readily 

available. While we are confident with the ability of Method 21 to detect fugitive 

emissions and therefore consider it a viable alternative to OGI, we solicit comment on the 

appropriate fugitive emissions repair threshold for Method 21 monitoring surveys and resurveys.” 

8. Reviewer recommends not performing LDAR at well sites unless there are gathering 

lines or well head pressure greater than 150 psi. Reviewer also recommends EPA take 

comment on varying survey frequencies based on performance criteria.

EPA RESPONSE: 

Although we agree that pressure can have an effect on occurrence and magnitude of some 

leaks causing fugitive emissions, we do not have information that would support a 

specific threshold. We also note that many fugitive emissions are related to flash 

emissions from storage vessels combined with undersized closed vent systems that are 

required to be designed to convey all emissions from the storage vessel to the control 

device. These emissions are independent of gathering line pressure.