```

[Federal Register Volume 80, Number 155 (Wednesday, August 12, 2015)]
[Rules and Regulations]
[Pages 48262-48268]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-19733]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2010-0505; FRL-9931-76-OAR]
RIN 2060-AS49

Oil and Natural Gas Sector: Definitions of Low Pressure Gas Well 
and Storage Vessel

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action finalizes amendments to new source performance 
standards (NSPS) for the Oil and Natural Gas Sector. On March 23, 2015, 
the Environmental Protection Agency (EPA) re-proposed its definition of 
``low pressure gas well'' for notice and comment to correct a 
procedural defect with its prior rulemaking that included this 
definition. The EPA also proposed to amend the NSPS to remove 
provisions concerning storage vessels connected or installed in 
parallel and to revise the definition of ``storage vessel.'' This 
action finalizes the definition of ``low pressure gas well'' and the 
amendments to the storage vessel provisions.

DATES: The final rule is effective on August 12, 2015.

ADDRESSES: The EPA has established a docket for this rulemaking under 
Docket ID Number EPA-HQ-OAR-2010-0505. All documents in the docket are 
listed in the www.regulations.gov index. Although listed in the index, 
some information is not publicly available, e.g., confidential business 
information or other information whose disclosure is restricted by 
statute. Certain other material, such as copyrighted material, is not 
placed on the Internet and will be publicly available only in hard 
copy. Publicly available docket materials are available either 
electronically in regulations.gov or in hard copy at the EPA Docket 
Center, EPA WJC West Building, Room 3334, 1301 Constitution Ave. NW., 
Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 
p.m., Monday through Friday, excluding legal holidays. The telephone 
number for the Public Reading Room is (202) 566-1744, and the telephone 
number for the EPA Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For further information on this 
action, contact Mr. Matthew Witosky, Sector Policies and Programs 
Division (E143-05), Office of Air Quality Planning and Standards, 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711, telephone number: (919) 541-2865; facsimile number: (919) 541-
3470; email address: witosky.matthew@epa.gov. For further information 
on the EPA's Oil and Natural Gas Sector regulatory program for air, 
contact Mr. Bruce Moore, Sector Policies and Programs Division (E143-
05), Office of Air Quality Planning and Standards, Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711, 
telephone number: (919) 541-5460; facsimile number: (919) 541-3470; 
email address: moore.bruce@epa.gov.

SUPPLEMENTARY INFORMATION: 

I. General Information

A. Does this reconsideration action apply to me?

    Categories and entities potentially affected by this action 
include:

[[Page 48263]]

----------------------------------------------------------------------------------------------------------------
           Category             NAICS code \1\                   Examples of regulated entities
----------------------------------------------------------------------------------------------------------------
Industry......................          211111  Crude Petroleum and Natural Gas Extraction.
                                        211112  Natural Gas Extraction.
                                        221210  Natural Gas Distribution.
                                        486110  Pipeline Distribution of Crude Oil.
                                        486210  Pipeline Transportation of Natural Gas.
Federal government............  ..............  Not affected.
State/local/tribal government.  ..............  Not affected.
----------------------------------------------------------------------------------------------------------------
\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
action. If you have any questions regarding the applicability of this 
action to a particular entity, consult either the air permitting 
authority for the entity or your EPA regional representative as listed 
in 40 CFR 60.4 (General Provisions).

B. How do I obtain a copy of this document and other related 
information?

    In addition to being available in the docket, an electronic copy of 
this action is available on the World Wide Web (WWW). Following 
signature by the EPA Administrator, a copy of this proposed action will 
be posted at the following address: http://www.epa.gov/airquality/oilandgas/actions.html.

C. Judicial Review

    Under section 307(b)(1) of the Clean Air Act (CAA), judicial review 
of this final rule is available only by filing a petition for review in 
the United States Court of Appeals for the District of Columbia Circuit 
by October 13, 2015. Under section 307(d)(7)(B) of the CAA, only an 
objection to this final rule that was raised with reasonable 
specificity during the period for public comment can be raised during 
judicial review. Moreover, under section 307(b)(2) of the CAA, the 
requirements established in this final rule may not be challenged 
separately in any civil or criminal proceedings brought by the EPA to 
enforce these requirements. Section 307(d)(7)(B) of the CAA further 
provides that ``[o]nly an objection to a rule or procedure which was 
raised with reasonable specificity during the period for public comment 
(including any public hearing) may be raised during judicial review.'' 
This section also provides a mechanism for us to convene a proceeding 
for reconsideration, ``[i]f the person raising an objection can 
demonstrate to the EPA that it was impracticable to raise such 
objection within the period for public comment (but within the time 
specified for judicial review) and if such objection is of central 
relevance to the outcome of the rule.'' Any person seeking to make such 
a demonstration to us should submit a Petition for Reconsideration to 
the EPA, Room 3000, EPA WJC West Building, 1200 Pennsylvania Ave. NW., 
Washington, DC 20460, with a copy to both the person(s) listed in the 
preceding FOR FURTHER INFORMATION CONTACT section, and the Associate 
General Counsel for the Air and Radiation Law Office, Office of General 
Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW., 
Washington, DC 20460.

II. Background

A. Low Pressure Gas Wells

    On August 23, 2011 (76 FR 52758), the EPA proposed the Oil and 
Natural Gas Sector NSPS (40 CFR part 60, subpart OOOO). Among the 
elements of the proposed rule were provisions for reduced emission 
completion (REC), also known as ``green completion'' of hydraulically 
fractured gas wells. In the proposal, the EPA solicited comment on 
situations where conducting a REC would be infeasible. Several 
commenters highlighted technical issues that prevent the implementation 
of a REC on what they referred to as ``low pressure'' gas wells because 
of the lack of the necessary reservoir pressure to flow at rates 
appropriate for the transportation of solids and liquids from a 
hydraulically fractured gas well completion against additional 
backpressure which would be caused by the REC equipment. Based on our 
analysis of the public comments received, we determined that there are 
certain wells where a REC is technically infeasible because of the 
characteristics of the reservoir and the well depth that will not allow 
the flowback to overcome the gathering system pressure due to the 
additional backpressure imposed by the REC surface equipment.
    On August 16, 2012, the EPA published the final NSPS (77 FR 49490). 
Under the 2012 NSPS, a REC is not required for well completions of low 
pressure gas wells. Rather, the 2012 final NSPS requires at 40 CFR 
60.5375(f) that well completions of low pressure gas wells using 
hydraulic fracturing meet the requirements for combustion of flowback 
emissions and to the general duty to safely maximize resource recovery 
and minimize releases to the atmosphere required under 40 CFR 
60.5375(a)(4).
    The 2012 NSPS includes a definition of ``low pressure gas well'' 
that is based on a mathematical formula that takes into account a 
well's depth, reservoir pressure, and flow line pressure. Section 
60.5430 defines low pressure gas well as ``a well with reservoir 
pressure and vertical well depth such that 0.445 times the reservoir 
pressure (in psia) minus 0.038 times the vertical well depth (in feet) 
minus 67.578 psia is less than the flow line pressure at the sales 
meter.''
    Following publication of the 2012 NSPS, a group of petitioners, led 
by the Independent Petroleum Association of America (IPAA), 
representing independent oil and natural gas owners and operators, 
submitted a joint petition for administrative reconsideration of the 
rule. The petitioners questioned the technical merits of the low 
pressure well definition and asserted that the public had not had an 
opportunity to comment on the definition because it was added in the 
final rule.\1\
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    \1\ Letter from James D. Elliott, Spilman, Thomas & Battle PLLC, 
to Lisa P. Jackson, EPA Administrator, October 15, 2012; Petition 
for Administrative Reconsideration of Final Rule ``Oil and Natural 
Gas Sector: New Source Performance Standards and National Emission 
Standards for Hazardous Air Pollutants Reviews,'' 77 FR 49490 
(August 16, 2012).
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    On March 24, 2014, the petitioners submitted to the EPA a suggested 
alternative definition \2\ for consideration. The petitioners' 
definition is based on the fresh water hydrostatic gradient of 0.433 
pounds per square inch per foot (psi/ft). The petitioners assert that 
this approach is straightforward and has been recognized for many years 
in the oil and natural gas industry and by governmental agencies and 
professional organizations. As expressed in the paper submitted by the

[[Page 48264]]

petitioners, the alternative definition for consideration by the EPA, 
as stated by the petitioners, would be ``a well where the field 
pressure is less than 0.433 times the vertical depth of the deepest 
target reservoir and the flow-back period will be less than three days 
in duration.''
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    \2\ Email from James D. Elliott, Spilman, Thomas & Battle PLLC, 
to Bruce Moore, EPA, March 24, 2014.
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    On July 17, 2014, the EPA proposed clarifying amendments to the gas 
well completion provisions of the NSPS. In the July proposal, we re-
proposed the definition of ``low pressure gas well'' for notice and 
comment. We also discussed the alternative definition provided by the 
IPAA. Specifically, we expressed concern that the IPAA alternative 
definition is too simplistic and may not adequately account for the 
parameters that must be considered when determining whether a REC would 
be feasible for a given hydraulically fractured gas well. We expressed 
disagreement with the petitioners' assertion that the EPA definition is 
too complicated and that it would pose difficulty or hardship for 
smaller operators. However, we agreed with the petitioners that the 
public should have been provided an opportunity to comment on the 2012 
definition of ``low pressure gas well,'' and we, therefore, re-proposed 
the 2012 definition for notice and comment. In addition, we solicited 
comment on the alternative definition suggested by the petitioners.
    On August 18, 2014, prior to the close of the public comment period 
for the July 17, 2014, proposal, the IPAA, on behalf of the independent 
oil and natural gas owner and operator petitioners, submitted a comment 
to the EPA via the email address to the Air and Radiation Docket 
provided in the proposed rule.
    The EPA published final amendments in the Federal Register at 79 FR 
79018 on December 31, 2014, which finalized the definition of ``low 
pressure gas well'' unchanged from the 2012 definition. Subsequent to 
the December 31, 2014, publication of the final amendments, the EPA 
became aware that the comment submitted by the IPAA was not made part 
of the record in the docket and, thus, was not available to be 
considered by the EPA in its decision-making process prior to 
finalizing the amendments. On March 23, 2015 (80 FR 15180), the EPA re-
proposed the definition of ``low pressure gas well'', and took comment 
on IPAA's alternative definition to correct the procedural defect.

B. Storage Vessels Connected in Parallel

    In the December 31, 2014, final rule, the EPA finalized amendments 
to the NSPS to address, among other issues, the affected facility 
status of storage vessel affected facilities. The final action included 
amendments related to storage vessels ``connected in parallel'' or 
``installed in parallel.'' As we explained in the final rule preamble 
(79 FR 79027), ``Although we believe it is an unlikely occurrence, we 
note that, when two or more storage vessels receive liquids in 
parallel, the total throughput is shared between or among the parallel 
vessels and, in turn, this causes the PTE of each vessel to be a 
fraction of the total PTE.'' To address such isolated occurrences where 
storage vessels are installed or connected to reduce the potential to 
emit (PTE) and, therefore, avoid being subject to 40 CFR part 60, 
subpart OOOO, we amended the NSPS to address situations in which two or 
more storage vessels could be installed or connected in parallel which 
could, in some cases, lower the PTE of the individual storage vessels 
to levels below the 6 tons per year (tpy) applicability threshold 
provided in 40 CFR 60.5365(e). Specifically, we amended 40 CFR 
60.5365(e)(4) to provide that a storage vessel that is being placed 
into service, and is connected in parallel with a storage vessel 
affected facility, is immediately subject to the same requirements as 
the affected facility with which it is being connected in parallel. We 
also amended the definitions for ``returned to service'' and ``storage 
vessel'' in 40 CFR 60.5430 to provide that two or more storage vessels 
connected in parallel are considered equivalent to a single storage 
vessel with throughput equal to the total throughput of the storage 
vessels connected in parallel.
    Following publication of the December 2014 final rule, we became 
aware that the terms ``connected in parallel'' and ``installed in 
parallel'' inadvertently included storage vessels beyond those we 
attempted to address as described above. On February 19, 2015, the Gas 
Processors Association (GPA) submitted a petition for administrative 
reconsideration of the December 31, 2014, amendments. The GPA asserted 
that ``it is quite common for multiple storage vessels to be situated 
next to each other and connected in parallel. Sometimes the storage 
vessels are operated in parallel, sometimes they are operated in 
series, and sometimes they are operated one-at-a-time with the 
connecting valves closed.'' The GPA further asserted that this 
configuration has existed for decades and that ``this language 
potentially has large impacts to how our members evaluate affected 
facility status.'' For the reasons discussed above, we proposed to 
remove the regulatory provisions relative to storage vessels 
``installed in parallel'' or ``connected in parallel.''

III. Summary of Final Amendments

    This section presents a summary of the provisions of the final 
action with brief explanations where appropriate. In some cases, 
additional detailed discussions are provided in section IV and V of 
this preamble, as well as the Response to Comment document. The final 
amendments include revisions to certain reconsidered aspects of the 
2012 NSPS as follows: (1) Definition of ``low pressure gas well''; (2) 
definition of ``returned to service''; (3) definition of ``storage 
vessel''; (4) revision of 40 CFR 60.5365(e)(4) to remove the phrases 
``or is installed in parallel with any storage vessel affected 
facility,'' and ``or with which it is installed in parallel.''

A. Low Pressure Gas Wells

    The EPA is finalizing its definition of ``low pressure gas well.'' 
For the purposes of 40 CFR part 60, subpart OOOO, our definition of low 
pressure gas well is for a singular purpose--to identify the wells that 
cannot implement a REC because of a lack of necessary reservoir 
pressure to flow gas at rates appropriate for the transportation of 
solids and liquids from a hydraulically fractured gas well against 
additional backpressure that would be caused by the REC equipment, 
thereby making a REC infeasible (80 FR 15182).
    In response to comments, we are amending the definition of ``low 
pressure gas well'' in this final action by changing ``vertical depth'' 
to ``true vertical depth.'' This change more accurately reflects our 
intent when formulating the definition of ``low pressure gas well.''

B. Storage Vessels Connected in Parallel

    The EPA is revising the definition of ``storage vessel'' to remove 
references to ``connected in parallel'' and ``installed in parallel'' 
from the current definition, and making associated changes to 40 CFR 
60.5365(e)(4). We are not making any changes to the proposed definition 
of ``storage vessel.''

IV. Significant Changes Since Proposal

    There is only one significant change since proposal, which is to 
refer to ``true vertical depth'' (instead of ``vertical depth'') in the 
definition of ``low pressure gas well.'' Several commenters took issue 
that the proposal definition of ``low pressure gas well'' does not take 
into account the ``true vertical depth'' of the well, as the ``vertical 
depth'' of the

[[Page 48265]]

well can overstate actual vertical depth because well bores may not be 
absolutely vertical. The commenters concluded that measured vertical 
depth often exceeds the true vertical depth of a well bore. The 
commenters believe this is an important distinction, especially for 
directional or horizontal wells, that should be clarified in the 
definition.
    We agree with the commenters that ``true vertical depth'' is more 
accurate terminology that better represents our intent. In light of the 
above considerations, we are amending the definition of ``low pressure 
gas well'' in this action by changing ``vertical depth'' to ``true 
vertical depth.''

V. Summary of Significant Comments and Responses

    This section summarizes the significant comments on our proposed 
amendments and our responses.

A. Definition of ``Low Pressure Gas Well''

    Comment: One commenter noted that the EPA's defense of the low 
pressure well definition focuses on the level of burden the definition 
imposes on the industry. The commenter contended that the EPA is 
missing the point with this response. The commenter contended that 
their concern is not the hardship imposed by the calculation required 
by the definition but rather that the definition does not accurately 
depict what historically has been considered to be a low pressure gas 
well. Thus, according to the commenter, the current definition would 
require RECs to be performed on marginally cost-effective wells.
    Response: In the 2012 rulemaking, EPA concluded that the BSER for 
well completion was a combination of REC and combustion; however, in 
response to comment that REC is not technically feasible for ``low 
pressure gas wells'' due to the inability of such wells to attain a gas 
velocity sufficient to clean up the well when flowing against the 
backpressure imposed by the surface equipment and the flow line 
pressure, the EPA exempted ``low pressure gas wells'' from REC in the 
2012 NSPS. The EPA subsequently re-proposed its ``low pressure gas 
well'' definition in response to an administrative petition that notice 
or an opportunity to comment was not provided for the EPA's 2012 
definition of ``low pressure gas well.'' However, rather than 
commenting on parameters for defining ``technical infeasibility'' to 
implement REC, the commenter asks the EPA to consider other burdens and 
hardships in defining ``low pressure wells.'' In the 2015 re-proposal 
of the ``low pressure gas well'' definition, the EPA did not propose or 
otherwise contempt exempting well completions from performing REC for 
reasons beyond technical infeasibility. This request is thus beyond the 
purpose and scope of this re-proposal, which is to provide a low 
pressure well definition that would accurately describe wells for which 
REC is technically infeasible due to low pressure and, therefore, 
exempt from the REC requirements under 40 CFR part 60, subpart OOOO.
    Comment: Several commenters expressed support for the alternative 
definition of ``low pressure gas well'' provided by IPAA as being more 
representative of current industry practice of defining these wells.
    According to one commenter, the alternative definition is based on 
the fresh water gradient, is widely used in industry, and appropriately 
describes the well conditions where installation of REC equipment is 
impractical. The commenter stated that the fresh water gradient (i.e., 
0.433 psi/ft or 8.33 pounds(lbs)/gallon (gal) x 0.052 x True Vertical 
Depth (TVD)) represents normally pressured wells based on the 
hydrostatic overhead pressure of fresh water that increases linearly 
with TVD. If reservoir pressure is less than the hydrostatic pressure 
of water, the well will not flow on its own because of the overhead 
pressure of fracture fluids in the wellbore that will be higher than 
the reservoir pressure which may make REC equipment impractical. The 
commenter added that whether a well's productive reservoir pressure is 
above or below the water gradient may be readily confirmed by reading 
offset reservoir pressure data in the development field or by 
evaluating certain wireline well logs that may be run after drilling a 
well before well completion begins.
    Another commenter stated that the EPA's current definition does not 
accurately define what industry has historically defined and recognized 
as a low pressure well. According to the commenter, because EPA's 
definition does not accurately delineate low pressure wells, the 
current definition will subject a subset of wells to RECs where the 
operation of a separator is not physically possible, thereby making the 
wells uneconomical as a result of being subject to REC requirements. 
The commenter included a table showing the values calculated using the 
EPA's definition for various well depths and flow line pressures. 
According to the commenter, the alternate definition would classify all 
of the values in the table as a low pressure well, while the EPA's 
definition would only consider about a quarter of the wells as low 
pressure.
    The commenter further stated that the permeability of the reservoir 
and other reservoir characteristics play a critical role in determining 
when a well is low pressure well or under-pressured. In addition to 
overcoming the hydrostatic pressure and sale line pressure, the 
separator necessary for the REC adds to the pressure which must be 
overcome for gas to flow from the reservoir. The commenter stated that 
the separator pressure is arguably the controlling parameter on when a 
REC is feasible versus the sales line pressure. Unlike the sales line 
pressure, which is easily known, the commenter contended that the 
separator pressure can vary greatly depending on gas and liquid rates, 
liquid composition, and equipment limitations. The commenter pointed 
out that the EPA's definition does not take separator pressure into 
account, thereby making the definition overly conservative. The 
commenter admitted that the alternative definition does not contain an 
adjustment for separator pressure either, but the definition is more 
accurate and is inclusive of wells recognized by the industry as ``low 
pressure.''
    In addition to the pressure associated with the separator, the 
commenter stated that in order for a separator to function, there must 
be a sufficient volume of gas (at appropriate pressure) to lift the 
associated liquids and overcome the pressure of the separator. The 
commenter added that if that gas rate is not achieved, the well will 
load up and a REC will not be possible. According to the commenter, the 
gas rate necessary for a REC varies based on reservoir pressure and 
casing/tubing diameter. The commenter provided a graph of Coleman 
curves to illustrate this point, which illustrates that as the pressure 
and casing diameter increase, so must the gas rate.
    Response: The EPA believes that the alternative definition of ``low 
pressure gas well,'' based only on fresh water gradient, may not 
adequately account for the parameters that must be taken into account 
when determining whether a REC would be feasible for a given 
hydraulically fractured gas well. We believe that, to determine whether 
the flowback gas has sufficient pressure to flow into a flow line, it 
is necessary to account for reservoir pressure, well depth, and flow 
line pressure. In addition, it is important for any such determination 
to take into account pressure losses in the surface equipment used to 
perform the REC. The EPA's definition in the proposed rule was 
developed to account for these factors.

[[Page 48266]]

    The EPA agrees that there must be a sufficient volumetric flow of 
gas (caused by adequate reservoir pressure) to lift the associated 
liquids and overcome the pressure of the separator, enabling the gas to 
be collected (i.e., enter the flow line). However, the EPA disagrees 
that the current definition, which we re-proposed for notice and 
comment, does not take into account the additional backpressure caused 
by the REC equipment, including a separator. The model uses an energy 
balance to determine the pressure drop based on the calculated 
velocity, and then the model accounts for pressure losses caused by REC 
equipment, including the separator. The result of the model is a 
prediction of the pressure of the flowback gas immediately before it 
enters the flow line. The result can be compared to the actual flow 
line pressure available to the well. For wells with insufficient 
pressure to produce into the flow line, as predicted using the EPA 
equation, combustion must be used to control emissions. For wells with 
sufficient pressure to produce into the flow line, gas capture in 
combination with combustion must be used to control emissions.
    According to some of the commenters, the EPA's definition of low 
pressure gas well should be revised because it does not comport with 
what the industry has historically considered to be a low pressure gas 
well. We are not making a determination on the similarity of the two 
definitions because we do not believe that the two must be the same for 
purposes of the Oil and Gas NSPS. The EPA has provided a definition of 
``low pressure gas well'' in the NSPS in order to designate a class of 
wells where a REC is not technically feasible. Our definition of ``low 
pressure gas well'' in the NSPS is for a singular purpose--to identify 
the wells that cannot implement a REC because of a lack of necessary 
reservoir pressure to flow gas at rates appropriate for the 
transportation of solids and liquids from a hydraulically fractured gas 
well during flowback against additional backpressure which would be 
caused by the REC equipment, thereby making a REC technically 
infeasible (80 FR 15182). To the extent that the industry definition is 
different from the EPA definition, the industry likely defines a 
particular well as being low pressure for a variety of reasons.\3\ As 
such, it is not clear that a REC is not technically infeasible for all 
of the wells that the industry has historically considered to be ``low 
pressure wells.''
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    \3\ ``USEPA's proposed low pressure well definition forces 
controls on a segment of the industry that have no or minimal 
beneficial impact on the environment while imposing significant 
additional costs that will make drilling and operating such wells 
uneconomical.'' (James Elliott, Spilman Thomas & Battle, PLLC, on 
behalf of Independent Petroleum Association of America et al., 
August 8, 2014)
---------------------------------------------------------------------------

B. Revisions to the Alternate Definition

    Comment: One commenter stated that the alternative definition 
should also be clarified to state ``where field reservoir pressure is 
less than 0.433 times the true vertical depth of the reservoir.'' 
According to the commenter, referring to reservoir pressure adds 
clarity and true vertical depth is a well-known standard term in the 
industry to differentiate from ``measured depth,'' where measured depth 
is the length of the well. The commenters stated this is an important 
distinction, especially for directional or horizontal wells, that 
should be clarified in the low pressure well definition.
    Another commenter similarly suggested that instead of defining the 
term ``low pressure gas well'' in terms of the ``vertical depth'' of 
the deepest target reservoir, it should instead by defined in terms of 
the ``true vertical depth.'' The commenter cited to the Schlumberger 
online Oil Field Glossary, which defines ``true vertical depth'' as 
follows:
    The vertical distance from a point in the well (usually the current 
or final depth) to a point at the surface, usually the elevation of the 
rotary kelly bushing (RKB). This is one of two primary depth 
measurements used by the drillers, the other being measured depth. TVD 
is important in determining bottomhole pressures, which are caused in 
part by the hydrostatic head of fluid in the wellbore. For this 
calculation, measured depth is irrelevant and TVD must be used. For 
most other operations, the driller is interested in the length of the 
hole or how much pipe will fit into the hole. For those measurements, 
measured depth, not TVD, is used. While the drilling crew should be 
careful to designate which measurement they are referring to, if no 
designation is used, they are usually referring to measured depth. Note 
that measured depth, due to intentional or unintentional curves in the 
wellbore, is always longer than true vertical depth.
    The commenter stated that it would be better to use ``true vertical 
depth'' because the measured vertical depth can overstate actual 
vertical depth because well bores may not be absolutely vertical. Thus, 
measured vertical depth often exceeds the true vertical depth of a well 
bore.
    One commenter stated that the IPAA's proposed definition for ``low 
pressure well'' was based on the weight of fresh water (8.33 lbs/gal) 
which is stacked on top of itself, and is known as hydrostatic 
pressure. Converting the density of fresh water to a pressure gradient 
results in 8.33 lb/gal being equal to 0.433 psi/ft. Therefore, the 
pressure of fresh water in the well bore is 0.433 psi/ft times the 
vertical well depth.
    The commenter added that in reality, the fluid flowing to the 
surface could be fresh water, re-used hydraulic fracturing water, re-
used, produced water, or a mixture. Additionally, in the beginning of 
the operation, the commenter stated that initial fluids flowing to the 
surface are essentially the fracturing fluids put down hole. At the end 
of the operation, the fluids flowing to the surface will mainly consist 
of reservoir fluids, and the water will be more of a brine water and 
not fresh water. The commenter added that brine water has a greater 
density, and more reservoir pressure will be required to lift the fluid 
to the surface. The commenter contended that the use of a fresh water 
gradient of 0.433 psi/ft should be used to keep the definition 
conservative and simple.
    As an alternative, or in addition, to a fresh water gradient, the 
commenter recommended that the density of brine water influenced by 
sand or proppant should be used to more accurately reflect the pressure 
of the water column in the well bore. The commenter pointed out that 
the EPA appears to have utilized a gradient of 0.4645 psi/ft in the 
``Lessons Learned from Natural Gas STAR Partners; Reduced Emissions 
Completions for Hydraulically Fractured Natural Gas Wells'' paper 
developed as a part of the EPA's Natural Gas STAR Program. The 
commenter stated that this is evidenced by the gradients listed in 
Exhibit 5 of the paper. Additionally, to perform a REC, the commenter 
contended that the downhole reservoir pressure must be sufficient 
enough to lift the hydraulic fracturing fluid to the surface and 
through the separation equipment and piping, with the resulting gas 
still having enough backpressure for it to get into the natural gas 
gathering line. According to the commenter, to combust flowback 
emissions the downhole reservoir pressure must be sufficient enough to 
lift the hydraulic fracturing fluid to the surface and through the 
separation equipment and piping, with the resulting gas still having 
enough backpressure to flow to a flare or enclosed combustion device.
    To reflect these realities, the commenter proposed that no emission

[[Page 48267]]

control be required when the following scenario exists:

    A well where the reservoir pressure is less than 0.4645 times 
the vertical depth of the deepest target reservoir.

    At reservoir pressures below this value, the commenter contends 
that insufficient pressure exists for any gas to flow to a flare, 
enclosed combustion device or the process. Consequently, the commenter 
proposes that combustion through a flare or enclosed combustion device 
be required when the following scenario exists:

    A well where the reservoir pressure is less than 0.4645 times 
the vertical depth of the deepest target reservoir plus the 
gathering or sales line pressure.

    At reservoir pressures less than the sum of the water column 
pressure and the sales line pressure, the commenter contended that the 
recovered gas will not naturally flow into the sales line. The 
commenter stated that the proposed rule does not require compression of 
recovered gas into the sales line. The commenter further states that 
the EPA has recognized this type of simpler approach in estimating the 
level of pressure necessary for recovered gas to flow into a gathering 
or sales line in their Gas STAR document cited above. In this Gas STAR 
paper, a table (Exhibit 5) is provided that shows the pressures 
necessary for various well depths. For instance, the commenter pointed 
out that the document indicates that the reservoir pressure necessary 
to flow recovered gas into a sales line for a 10,000-foot well would be 
4,645 psig plus the sales line pressure.
    Response: We agree with the commenters that ``true vertical depth'' 
is more accurate terminology that better represents our intent. 
Although we are not adopting the alternative definitions for the 
reasons presented above, we are amending the current definition of low 
pressure gas well to include ``true vertical depth.''

C. Storage Vessel Requirements

    Comment: One commenter acknowledged the EPA's proposal to remove 
provisions relating to storage vessels ``installed in parallel'' or 
``connected in parallel'' because these provisions ``inadvertently'' 
encompassed storage vessels the Agency did not intend to address. 
However, the commenter contended that the EPA does not identify those 
vessels that it believes were inadvertently covered in the December 
2014 rule, nor does it propose alternative regulatory language that 
would ensure adequate control measures for vessels connected or 
installed in parallel that were intended to be covered under the 
December 2014 rule.
    Given that storage vessels, including those installed or connected 
in parallel, can be significant sources of emissions, the commenter 
opposed the EPA's proposal to simply remove any provisions addressing 
these vessels. Instead of removing all provisions regarding vessels 
installed or connected in parallel, as the Agency proposed, the 
commenter urged the EPA to instead clarify its existing requirements 
for such vessels. The commenter suggested that the EPA could, for 
instance, clarify that pollution control measures apply to storage 
vessels operated in parallel in the relevant regulatory provisions 
addressing storage vessel affected facilities and the definitions of 
``returned to service'' and ``storage vessel.''
    Response: The change to the definition of ``storage vessel'' is 
intended to preserve the original basis on individual storage vessels 
to determine affected facility status, while addressing the potential 
situation where the flow of crude oil, condensate, intermediate 
hydrocarbon liquids, or produced water is divided into two or more 
tanks operated in parallel (i.e., sharing the emissions at the 
correlated fraction of what a single tank would emit). Through comments 
submitted on the March 2015 proposed rule, the public has informed us 
that many storage vessels that are configured in parallel may not be 
operated or constructed to divide their potential to emit continuously, 
if ever. The EPA has now reconsidered our attempt to include storage 
vessels connected in parallel to address the specific situation 
resulting in circumvention. We believe that we do not have sufficient 
data to evaluate the scope of storage vessels that would fall under the 
amended definition and for which we did not intend to cover.
    We believe that we have sufficient provisions under the General 
Provisions at 40 CFR 60.12 ``Circumvention'' to address the specific 
situation where storage vessels are divided into smaller tanks to avoid 
applicability of the rule and which was our intent with the previous 
amended definition. Therefore, we do not believe that our reverting to 
the prior definition of ``storage vessel'' will affect our ability to 
ensure control of these storage vessels. Consequently, as proposed, we 
are finalizing the removal of provisions made in the 2014 amendment 
relating to storage vessels ``installed in parallel'' or ``connected in 
parallel.''

V. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at http://www2.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was, 
therefore, not submitted to the Office of Management and Budget (OMB) 
for review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA. OMB has previously approved the information collection 
requirements contained in the existing regulations and has assigned OMB 
control number 2060-0673. This action does not change the information 
collection requirements previously finalized and, as a result, does not 
impose any additional burden on industry.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities. This action 
is a reconsideration of an existing rule and imposes no new impacts or 
costs.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no enforceable duty on any state, 
local, or tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    This action does not have tribal implications as specified in 
Executive Order 13175. This action is a reconsideration of an existing 
rule and imposes no new impacts or costs. Thus, Executive Order 13175 
does not apply to this action.

[[Page 48268]]

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because it does not concern an environmental 
health risk or safety risk.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211 because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    The EPA believes the human health or environmental risk addressed 
by this action will not have potential disproportionately high and 
adverse human health or environmental effects on minority, low-income, 
or indigenous populations because it does not affect the level of 
protection provided to human health or the environment. This action is 
a reconsideration of an existing rule and imposes no new impacts or 
costs.

K. Congressional Review Act (CRA)

    This action is subject to the CRA, and the EPA will submit a rule 
report to each House of the Congress and to the Comptroller General of 
the United States. This action is not a ``major rule'' as defined by 5 
U.S.C. 804(2).

List of Subjects in 40 CFR Part 60

    Administrative practice and procedure, Air pollution control, 
Environmental protection, Intergovernmental relations, Reporting and 
recordkeeping.

    Dated: July 31, 2015.
Gina McCarthy,
Administrator.

    For the reasons set out in the preamble, title 40, chapter I of the 
Code of Federal Regulations is amended as follows:

PART 60--STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES

0
1. The authority citation for part 60 continues to read as follows:

    Authority:  42 U.S.C. 7401, et seq.

Subpart OOOO--Standards of Performance for Crude Oil and Natural 
Gas Production, Transmission, and Distribution

0
2. Section 60.5365(e)(4) is revised to read as follows:

Sec.  60.5365   Am I subject to this subpart?

* * * * *
    (e) * * *
    (4) For each new, reconstructed, or modified storage vessel with 
startup, startup of production, or which is returned to service, 
affected facility status is determined as follows: If a storage vessel 
is reconnected to the original source of liquids or is used to replace 
any storage vessel affected facility, it is a storage vessel affected 
facility subject to the same requirements as before being removed from 
service, or applicable to the storage vessel affected facility being 
replaced, immediately upon startup, startup of production, or return to 
service.
* * * * *

0
3. Section 60.5430 is amended by revising the definitions for ``Low 
pressure gas well,'' ``Returned to service,'' and the first three 
sentences in the introductory text of ``Storage vessel'' to read as 
follows:

Sec.  60.5430  What definitions apply to this subpart?

* * * * *
    Low pressure gas well means a well with reservoir pressure and 
vertical well depth such that 0.445 times the reservoir pressure (in 
psia) minus 0.038 times the true vertical well depth (in feet) minus 
67.578 psia is less than the flow line pressure at the sales meter.
* * * * *
    Returned to service means that a Group 1 or Group 2 storage vessel 
affected facility that was removed from service has been:
    (1) Reconnected to the original source of liquids or has been used 
to replace any storage vessel affected facility; or
    (2) Installed in any location covered by this subpart and 
introduced with crude oil, condensate, intermediate hydrocarbon liquids 
or produced water.
* * * * *
    Storage vessel means a tank or other vessel that contains an 
accumulation of crude oil, condensate, intermediate hydrocarbon 
liquids, or produced water, and that is constructed primarily of 
nonearthen materials (such as wood, concrete, steel, fiberglass, or 
plastic) which provide structural support. A well completion vessel 
that receives recovered liquids from a well after startup of production 
following flowback for a period which exceeds 60 days is considered a 
storage vessel under this subpart. A tank or other vessel shall not be 
considered a storage vessel if it has been removed from service in 
accordance with the requirements of Sec.  60.5395(f) until such time as 
such tank or other vessel has been returned to service. * * *
* * * * *
[FR Doc. 2015-19733 Filed 8-11-15; 8:45 am]
 BILLING CODE 6560-50-P
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