MACT, AMOS and other regulatory requirements. Therefore, we have
decided to propose the thresholds that are used in the HON (see Table 1
of this preamble). These thresholds are widely applicable because many
current rules reference the HON, and we think they represent the best
choice as defaults for the Uniform Standards. We request comment on
this decision.
    For most chemical manufacturing facilities, the costs to comply
with the combined requirements of Control Options ST1, ST2, ST3 and ST4
for atmospheric storage vessels above the proposed thresholds are
expected to be zero or minimal because they are already subject to
current rules that have the same or similar thresholds and control
requirements. However, many storage vessels at petroleum refineries are
subject to 40 CFR part 63, subpart CC, which does not require control
of deck fittings (i.e., Control Options ST2 and ST4). Based on
information provided by petroleum refiners in response to an
information request, we determined that nationwide there are
approximately 2,400 storage vessels with an EFR and 1,400 storage
vessels with an IFR that meet or exceed the proposed thresholds in
Table 1 of this preamble and about 60 percent of these storage vessels
have slotted guidepoles (see the petroleum refinery database in Docket
ID No. EPA-HQ-OAR-2010-0682). About 50 percent of the IFR storage
vessels that have slotted guidepoles are controlled, and about two-
thirds of the EFR storage vessels that have slotted guidepoles are
controlled. We assumed all of the other fittings have typical controls
(i.e., consistent with Control Options ST1 and ST3). We also assumed
each EFR is equipped with two rim seals, as required in 40 CFR part 63,
subpart CC, and in Control Option ST3. To estimate current annual
emissions, we first represented each storage vessel with one of four
model sizes. Each model storage vessel also was assigned one of four
model liquids, depending on the reported vapor pressure of the actual
stored liquid. Storage vessels containing liquids with the lowest vapor
pressures were represented with methyl ethyl ketone. The other storage
vessels were organized into three groups, each of which was represented
with a different grade of gasoline.
    We estimated the current and controlled emissions for each model-
refinery storage vessel using the AP-42 procedures and other
assumptions, as described above in the discussion of the analysis to
establish thresholds for control. We estimated costs to upgrade
fittings for each storage vessel using the same information that we
used in the analysis to establish thresholds for control. We also
applied a product recovery credit of $500/ton of VOC to the prevented
emissions. The emission reductions associated with upgrading the deck
fittings on EFR storage vessels, particularly slotted guidepoles,
resulted in a product recovery credit that exceeded the estimate of all
costs associated with Control Options ST2 and ST4. Thus, the nationwide
impacts of the control options for petroleum refineries is a cost
savings of about $350/ton of VOC controlled. See the memorandum titled
Survey of Control Technology for Storage Vessels Analysis of Impacts
for Storage Vessel Control Options, in the docket for proposed subpart
I for additional discussion of how these impacts were developed.
3. How did the EPA determine the control and compliance requirements
for fixed roof atmospheric storage vessels?
    All atmospheric storage vessels below the capacity and MTVP
thresholds noted in section III.A.2 of this preamble would have to be
equipped with a fixed roof. Although most current rules do not specify
standards for such storage vessels, we expect that storage vessels at
facilities that may in the future be subject to rules that reference
the Uniform Standards already meet this proposed requirement. Thus, we
do not expect any cost or emission impacts to meet this requirement. We
request comment on the accuracy of this assumption.
    The design and operating requirements that we are proposing for
fixed roofs are based on the requirements in the Generic MACT for Tanks
Level 1. However, we are proposing the seven changes to the
requirements in the Generic MACT for Tanks Level 1, described below, to
control more effectively fugitive emissions, simplify requirements and
enhance consistency with requirements for storage vessels that may be
subject to other sections in proposed subpart I.

    First, we are not proposing to specify suitable materials for the
fixed roof and closure devices. We decided that these decisions are
best left to you and the storage vessel manufacturer. You would have
the flexibility to choose whatever materials work best in your
situation, provided you meet the design and operational requirements in
proposed subpart I.
    Second, like the Generic MACT for Tanks Level 1, proposed subpart I
would allow opening of a closure device or removal of the roof when
needed to provide access. The Generic MACT for Tanks Level 1 specifies
that the closure devices may be opened to provide access for
``performing routine inspection, maintenance, or other activities
needed for normal operations'' and ``to remove accumulated sludge or
other residues from the bottom of the tank.'' In proposed subpart I, we
use an edited version of these statements to clarify that the opening
is allowed for ``manual operations that require access such as
inspections, maintenance, sampling, and cleaning.'' A related
difference between the Generic MACT for Tanks Level 1 and the proposed
rule is that the proposed rule does not explicitly state that the
closure device must be secured in the closed position or the roof
reinstalled when the activity that requires access is complete. Such a
statement is unnecessary, because the inverse of the provision allows
openings when access is needed. The proposed rule clearly states that
closure devices must be closed at all times except when access is
needed.
    Third, as in the Generic MACT for Tanks Level 1, proposed subpart I
would allow you to route emissions from an opening through a closed
vent system to a control device as an alternative to equipping the
opening with a closure device. However, the Generic MACT for Tanks
Level 1 does not specify compliance procedures for this control option.
To ensure that emission reductions are consistent and quantifiable when
a control device is used, we are proposing to require compliance with
the procedures in proposed 40 CFR 65.325 for closed vent systems and
control devices.
    Fourth, the Generic MACT for Tanks Level 1 specifies at 40 CFR
63.902(c)(3) that opening of a safety device is allowed at any time.
This provision was not included in proposed subpart I because the
referencing subparts will address malfunctions.
    Fifth, we are proposing delay of repair provisions that differ from
the requirements in the Generic MACT for Storage Tanks Level 1. The
primary difference between the Generic MACT for Storage Tanks Level 1
and proposed subpart I is the time allowed to complete repair. The
Generic MACT for Tanks Level 1 allows delay as long as the owner or
operator demonstrates that alternative tank capacity is not available
to accept the regulated material from the tank that needs to be
repaired, whereas the proposed rule would allow a maximum delay of 105
days (45 days plus up to two extensions of up to 30 days each). We have
determined that 105 days is sufficient time to empty the tank, either
to other existing tanks on site or to temporary storage, if necessary.
Furthermore, current rules (and proposed subpart I) already include
such requirements for repair of any floating roof, and applying the
same requirements for fixed roof storage tanks would promote
consistency and reduce the likelihood of inadvertent compliance errors.
Sixth, we are proposing to require periodic monitoring of each
potential source of vapor leakage from the fixed roof and fittings on
the roof instead of annual visual inspections for defects. The
monitoring could be conducted annually using Method 21 of 40 CFR part
60, appendix A-7 or semiannually using optical gas imaging (after
promulgation of the protocol that we are developing for 40 CFR part 60,
appendix K). See sections III.A.3 and IV.A.5 of this preamble for
discussions of the protocol. Repairs would be required for each leak. A
leak would be defined as any instrument reading greater than 500 ppmv
when monitoring using Method 21 of 40 CFR part 60, appendix A-7, or any
emissions imaged when using an optical gas imaging instrument. We are
proposing this monitoring change to better control fugitive emissions.
As documented in the docket for proposed subpart I, EPA inspectors have
often found significant leaks from fittings by sensory means
(particularly olfactory) and optical gas imaging when visual
inspections indicate the gaskets and other elements of closure devices
appear to be sound, and the conservation vent is not actively releasing
to relieve increased pressure caused by diurnal temperature changes or
filling the storage vessel (see the memorandum titled Leaks Observed
From Fixed Roof and Floating Roof Fittings, in the docket for proposed
subpart I).
    The estimated annual costs, emission reductions and cost-
effectiveness values for the three monitoring options are shown in
Table 5 of this preamble. The estimated cost-effectiveness values for
monitoring using either optical gas imaging or Method 21 of 40 CFR part
60, appendix A-7 are less than $230/ton per storage vessel, which we
determined is reasonable. Note that the emission reductions for these
two options are relative to estimated uncontrolled emissions. We lack
the data needed to attempt to quantify the reductions for the visual
inspections option, but we expect the reductions to be significantly
less than for the other two options given the results of agency
inspections noted above.
    The impacts were estimated for a representative fixed roof storage
vessel with eight fittings on the roof (an access hatch, gauge hatch,
conservation vent, emergency pressure relief vent and four other
miscellaneous types of valves and instruments). Costs were estimated
assuming a visual inspection takes an average of 30 minutes and the
other monitoring options take between 40 minutes and an hour, depending
on the size of the facility at which the storage vessel is located.
Based on the results of agency inspections, we estimated that initial
optical gas imaging would find about 0.5 leaking fittings per storage
vessel, and that monitoring with Method 21 of 40 CFR part 60, appendix
A-7, would find an average of about 1 leaking fitting per storage
vessel. We assumed that subsequent monitoring would find about 5-
percent leaking fittings if optical gas imaging is conducted
semiannually and monitoring with Method 21 of 40 CFR part 60, appendix
A-7, is conducted annually. As in equipment leak analyses, repair costs
were estimated assuming 75 percent of the leaks could be eliminated by
a simple adjustment to the fitting and that 25 percent of the fittings
would require a more extensive repair or replacement. Recordkeeping
costs were estimated assuming 1 hr/yr to document the results of visual
inspections and 0.5 hr/yr to document the results of the other
monitoring options. Reporting costs were estimated assuming 0.5 hour
per reporting period, to include records in annual periodic reports of
inspections of each storage vessel for which a leak was found, and that
40 percent of the storage vessels have one leaking fitting each year
(i.e., 5 percent of the fittings are found to be leaking, and each tank
has an average of eight fittings). Uncontrolled emissions for the
conservation vent, emergency pressure relief vent and miscellaneous
valves were estimated using average emission factors from the Protocol
for Equipment Leaks Emission Estimates (EPA-453/R-95-017) for such
equipment in the SOCMI. Uncontrolled emissions for access hatches and
gauge hatches were approximated using AP-42 factors for such fittings
on EFR

(unbolted, gasketed cover for access hatches and gasketed, weighted
mechanical actuation gauge hatches). Controlled emissions were
estimated assuming the percent reduction in emissions equals the
percent reduction in the number of fittings found to be leaking.

                 Table 5--Estimated Impacts of Monitoring Options for Fixed Roof Storage Vessels
----------------------------------------------------------------------------------------------------------------
                                                                Emission
                                                                reduction           Cost        Incremental cost
            Monitoring option               Total annual       relative to      effectiveness     effectiveness
                                            cost  ($/yr)      uncontrolled         ($/ton)           ($/ton)
                                                                  (tpy)
----------------------------------------------------------------------------------------------------------------
Visual..................................               120           unknown           unknown               N/A
EPA Method 21...........................               170               1.1               150           unknown
Optical gas imaging.....................               260               1.1               230         undefined
----------------------------------------------------------------------------------------------------------------
tpy means tons per year.
N/A means not applicable.

    We request comment, with supporting rationale, on all aspects of
the proposed requirements for fixed roof storage vessels that store
regulated material. We are particularly interested in comment on the
proposed monitoring requirements. For example, itemized cost estimates,
data on mass emissions from leaks and information about the types of
initial repairs that would be needed and the expected frequency of
replacements would be useful. Comparisons of results obtained using
both Method 21 of 40 CFR part 60, appendix A-7, and optical gas imaging
are requested.
4. How did the EPA determine the proposed requirements for atmospheric
storage vessels that are controlled using an IFR or EFR?
    As noted in section III.A.2 of this preamble, we are proposing four
different compliance approaches for atmospheric storage vessels that
exceed specified capacity and MTVP thresholds. One of these approaches
is to use a floating roof. The requirements that we are proposing for
this approach in proposed 40 CFR 65.315 are essentially the same as the
requirements in the Generic MACT for Tanks Level 2. We are proposing
additional requirements and clarifications as described below.
    Rim seal design. The Generic MACT for Tanks Level 2 specifies
alternative rim seal configurations for IFR and EFR storage vessels at
40 CFR 63.1063(a)(1)(i) and (ii). However, if certain conditions are
met, 40 CFR 63.1063(a)(1)(i)(D) and (ii)(C) specify that full
compliance with these configurations is not required for existing tanks
until the next time the storage vessel is completely emptied and
degassed or 10 years after promulgation of the referencing subpart,
whichever occurs first. The storage vessel provisions in 40 CFR
63.119(b) and (c) of the HON contain the same provision. We are not
proposing this delayed compliance provision because we expect most
rules that reference the Uniform Standards will be amended versions of
current rules, and these amended rules will not reference the Uniform
Standards until more than 10 years after their original promulgation.
Thus, all existing storage vessels that are subject to a referencing
subpart should already be equipped with the required rim seals before
they become subject to the Uniform Standards.
    One of the objectives of rim seals is to help fill the annular
space between the rim of the floating roof and the wall of the storage
vessel thereby minimizing evaporative losses from this area. To meet
this objective, rim seals must be constructed of a material that is
impermeable to the stored material or any components of the stored
material. A rim seal that is saturated with (or has been plasticized
by) stored liquid would constitute an inspection failure because the
rim seal would not be functioning as designed. In proposed subpart I,
this requirement is specified in section 65.315(c)(1)(iii). We request
comment on whether explicitly stating in subpart I that rim seal
material saturated with (or plasticized by) stored liquid constitutes
an inspection failure would help clarify this requirement. We also
request comment on other possible approaches for clarifying this
requirement. In addition, we are interested in strategies that could
minimize repeated use of seal materials that are demonstrated to be
less reliable than others. For example, we request comment on the
feasibility and potential effectiveness of requiring more frequent
inspections if a seal that failed during the first 5 years of use is
replaced with a seal made from the same material.
    Sample well requirements. The Generic MACT for Tanks Level 2
specifies at 40 CFR 63.1063(a)(2)(v) that each sample well and each
deck drain that empties into the stored liquid may be equipped with a
slit fabric seal or similar device that covers at least 90 percent of
the opening instead of a deck cover. In other rules, such as the CAR,
the HON and Standards of Performance for Volatile Organic Liquid
Storage Vessels (Including Petroleum Liquid Storage Vessels) for Which
Construction, Reconstruction, or Modification Commenced After July 23,
1984 (40 CFR part 60, subpart Kb; ``NSPS Kb''), the option for sample
wells to use a slit fabric cover applies only for IFR. Therefore, to
clarify the requirement, we are proposing to split the requirements for
sample wells and deck drains into two paragraphs in subpart I. As an
alternative to using a gasketed deck cover, proposed 40 CFR
65.315(a)(3)(v) specifies that sample wells in IFR may be equipped with
a slit fabric seal (or similar device) that covers at least 90 percent
of the opening. Proposed 40 CFR 65.315(a)(3)(vi) specifies that each
opening for a deck drain (in any floating roof) that empties into the
stored liquid must be equipped with a slit fabric (or similar device)
that covers at least 90 percent of the opening.
    Control requirements for guidepoles. The Generic MACT for Tanks
Level 2 specifies in 40 CFR 63.1063(a)(2)(vii) that each unslotted
guide pole shall be equipped with a gasketed cap on the top of the
guide pole. We are proposing an alternative to this provision for
proposed 40 CFR 65.315(a)(3)(viii) to indicate that a welded cap is an
acceptable alternative to a gasketed cap for anti-rotational devices.
The cap may be welded on an unslotted guide pole because such a guide
pole is not used for gauging the liquid level. Emissions reductions are
expected to be the same for both types of caps.
    As part of the STERPP, we offered to enter into agreements with
companies that have installed or will install controls to reduce their
slotted guide pole emissions from storage vessels that

are subject to Standards of Performance for Storage Vessels for
Petroleum Liquids for Which Construction, Reconstruction, or
Modification Commenced After May 18, 1978, and Prior to July 23, 1984
(40 CFR part 60, subpart Ka) or NSPS Kb. During development of the
program, we identified two additional slotted guide pole control
options that are not included in the Generic MACT for Tanks Level 2.
The STERPP included these options because their performance was
determined to be comparable to the performance of other control options
already specified in the rules. One of the new options is to use a
flexible enclosure device that completely encloses the slotted guide
pole and a cover on the top of the guide pole. The second new option is
to install an internal guide pole sleeve, a pole wiper and a cover on
the top of the guide pole. We are proposing to include both of these
options in proposed 40 CFR 65.315(a)(3)(ix). As discussed above for
unslotted guidepoles, the cover may be either gasketed or welded. There
is no cost impact associated with these control options because these
options are providing compliance flexibility without imposing new
requirements.
    Control requirements for slotted ladder legs. Many IFR tanks have a
ladder with one slotted leg so that the leg can also be used for
gauging and/or sampling. Current rules specify that ladder wells must
have gasketed sliding deck covers, and slotted guidepoles must be
controlled using any one of several techniques. However, current rules
do not explicitly specify requirements for slotted ladder legs.
Therefore, we are proposing to require any one of three options for
this type of fitting. One option is to use a pole float in the slotted
leg and pole wipers for both legs. A second option is to use a ladder
sleeve and pole wipers for both legs. The third option is to use a
flexible device that completely encloses the ladder and either a
gasketed or welded cap on the top of the slotted leg. Each option also
includes the requirement to have a gasketed sliding deck cover. These
controls are similar to the controls for slotted guidepoles, and they
have been accepted in equivalency determinations for numerous storage
vessels that are subject to current rules. Thus, the costs to comply
with proposed subpart I would be the same as costs to comply with
current rules.
    Delayed compliance date for deck fitting requirements. The Generic
MACT for Tanks Level 2 specifies in 40 CFR 63.1063(a)(2)(ix) that deck
fitting requirements do not apply for an existing IFR or EFR until the
next time the storage vessel is completely emptied and degassed or 10
years after the promulgation date of the referencing subpart, whichever
occurs first. We have not included this provision in proposed subpart I
for the same reason described above regarding a similar provision for
rim seals (i.e., all existing storage tanks that may in the future be
subject to rules that reference the Uniform Standards should have
already complied with the deck fitting requirements before they become
subject to the Uniform Standards).
    Operational requirements. The Generic MACT for Tanks Level 2
requires that the floating roof float on the stored liquid surface at
all times, except for times when the floating roof is supported by its
leg supports or other support devices such as hangers from the fixed
roof (``landings''). Once the floating roof lands, ``the process of
filling to the point of refloating the floating roof shall be
continuous and shall be performed as soon as practical'' (40 CFR
63.1063(b)(2)), and you must keep records of the date the roof landed
and the date it was refloated (40 CFR 63.1065(c)). The language at 40
CFR 63.1063(b)(2) is similar to the language in the CAR (40 CFR
65.43(b) and 65.44(b)), and the preamble to the CAR has clarified that
the intent of this language is ``to prevent the liquid level [in the
storage vessel] from rising and falling while the roof is resting on
the supports'' (63 FR 57768, October 28, 1998). However, neither the
Generic MACT for Tanks Level 2 nor the CAR place any limits on the
number of landings or the amount of time that a floating roof may be
landed. The lack of limits is a concern because the standing idle
emissions can be significant, especially relative to the emissions and
emissions reductions for deck fittings while the roof is floating. For
example, Table 6 of this preamble presents estimated emissions from
typical gasoline storage tanks equipped with an EFR and standing idle
for 2 or 5 days. These emissions were estimated using AP-42 procedures
for a storage vessel in Corpus Christi, Texas. The landed height of the
roof was assumed to be 5 feet above the floor of the storage vessel,
and the liquid level was assumed to be 0.75 feet above the floor of the
storage vessel.

     Table 6--Estimated Standing Idle Emissions From Gasoline Storage Vessels That are Equipped With an EFR
----------------------------------------------------------------------------------------------------------------
                                                                                Estimated
        Size of storage vessel  (gal)                 Stored contents          Number of days     standing idle
                                                                                standing idle    emissions  (lb)
----------------------------------------------------------------------------------------------------------------
2,000,000...................................  gasoline......................                 2               830
                                                                                5             2,100
7,000,000...................................  gasoline......................                 2             1,500
                                                                                5             3,900
----------------------------------------------------------------------------------------------------------------

    Other rules (e.g., NSPS Kb) allow floating roof landings only if
the storage vessel is being completely emptied, and both the emptying
and refilling processes must be continuous and as rapid as possible.
This requirement has been interpreted as requiring the storage vessel
to be emptied each time the floating roof lands. However, as we
clarified in the preamble to the CAR (63 FR 57768), emptying the
storage vessel every time the roof lands is undesirable because it
increases the vapor space, which in turn increases emissions. Thus,
emptying the storage vessel when landings are inadvertent or other
times when emptying is not needed for operational reasons is
counterproductive.
    To minimize emissions from landings and clarify the requirements,
we are proposing several differences relative to the requirements in
current rules. For example, instead of requiring the floating roof to
be floating on the liquid surface at all times except when it is landed
on its supports, we are proposing to list specific situations under
which the floating roof is not required to be floating on the stored
liquid (proposed 40 CFR 65.315(b)(1)). We are proposing to allow the
roof to be landed during the

initial fill because the landed height is typically several feet above
the floor of the storage vessel. We are not proposing to require
control of emissions in displaced gases during the initial fill because
the average concentration of regulated materials in the vapor space
over the course of the fill is relatively low, and the costs to vent
such emissions to a control device are not reasonable. Like current
rules, however, the proposed rule typically would require filling to
the point of refloating the roof to be conducted continuously and as
rapidly as practicable to minimize the amount of time a vapor space is
present below the floating roof. The only exception to the proposed
requirement for continuous filling until the roof is refloated would be
for storage vessels that are used to store product from batch
processes. The exemption would apply if the quantity of product from
one batch is insufficient to refloat the roof, but sufficient product
from additional batches to refloat the roof will be added before any
material is withdrawn from the storage vessel.
    We also recognize that landings are required in order to take the
storage vessel out of service, and they are often required in order to
perform inspections, maintenance or before filling the storage vessel
with a liquid that is incompatible with the liquid currently stored in
the storage vessel. Therefore, we are proposing to allow roof landings
in these situations, provided the time spent standing idle is limited
to no more than 24 hours. After 24 hours, you would be required to
either begin actions to completely empty (and clean, if necessary) or
refill the storage vessel. These requirements clarify that you would
not be required to empty a storage vessel when the storage vessel does
not need to be empty in order to conduct maintenance or inspections.
The limited number of situations when landings are allowed is intended
to eliminate unnecessary or convenience landings, and the 24-hour limit
is intended to prevent emissions from unnecessary time spent standing
idle. We request comment on the suitability of the 24-hour limit. In
particular, we request comment on specific situations where a storage
vessel does not need to be completely emptied to perform maintenance or
inspection, but the maintenance or inspection activity cannot be
completed in less than 24 hours. We also request comment on the
proposed list of circumstances under which floating roof landings would
be allowed, in particular whether there are other circumstances that
would require a floating roof landing or whether the list allows
landings in situations where they are unnecessary.
    We are also proposing to allow landings if you elect to route
emissions through a closed vent system to a control device that reduces
emissions by at least 90 percent while the roof is landed because this
control technique will also reduce standing loss emissions relative to
uncontrolled landings. To prevent liquid from being drawn into the
closed vent system, control would be required only when the liquid
fills less than 90 percent of the volume under the landed roof. We are
not proposing to require control of displaced emissions during refill
after these events because the cost to control, considering the
estimated emissions reduction, would not be reasonable except for very
large storage vessels that store highly volatile material. We request
comment on the technical feasibility and cost of this control option.
In particular, we are interested in test data showing the gas flow rate
and inlet mass emissions to a control device that was used as we
proposed; please also provide related supporting information, such as
the diameter of the storage vessel, the height of the landed roof, the
average height of the liquid, the type of material stored and the
pressure drop across the floating roof. We also request comment on
whether the rule should limit the number of days operating in this
manner so that the total controlled emissions do not exceed the
standing idle emissions from one day. We also request comment on
whether any facilities would have no choice but to comply with this
control option because it would not be possible to limit landings to
the situations described in the paragraph above; please provide a
description of any such facilities and explain why limiting landings
would not be possible.
    Proposed subpart I would require you to estimate regulated material
standing idle emissions from each landing and to submit the results in
your next periodic report. As in the Generic MACT for Tanks Level 2,
you would also be required to keep records documenting the start and
end times of all roof landing events. We have determined that
maintaining information on the occurrence, time span and quantity of
standing idle emissions for landings is needed to demonstrate
compliance with the proposed limits on when landings are allowed. This
information will also help inform decisions about where to target
compliance inspections. We request comment on the feasibility and
burden of estimating emissions from landings.
    Monitoring and alarm systems. Under the proposed rule, an
inadvertent landing of a floating roof would be a deviation of the
operating requirements described above. To minimize the number of
unintended landings of floating roofs (and the additional emissions
generated as a result), we are proposing to require that you equip each
affected storage vessel with a system that provides a visual or audible
signal when the floating roof is about to land on its legs (or other
support devices). This monitoring is intended to alert you in time to
take action to prevent an inadvertent landing and the resulting
deviation. We are soliciting comment on the prevalence of such
monitoring systems in use with existing storage vessels and the burden
to add them to storage vessels that are not already so equipped. We
estimated the cost to plan, purchase and install the required monitors
to be about $2,000 per storage vessel. We estimated the annual costs,
including costs to estimate emissions for each landing and related
recordkeeping and reporting, to be about $900/year per storage vessel.
These estimates assume each floating roof will be landed an average of
two times per year, and that one of the landings will be inadvertent.
    IFR and EFR inspections. The proposed inspection requirements are
consistent with the inspection requirements in 40 CFR 63.1063(c) and
(d), except for the six proposed changes discussed below. First, in an
effort to improve clarity, we are proposing to tabulate many of the
inspection and frequency requirements (see Tables 2 and 3 in proposed
subpart I). The intent is not to change the requirements except as
discussed below.
    Second, we are proposing to specify how an inspector is to
demonstrate when a gap constitutes an inspection failure for a deck
fitting. The Generic MACT for Tanks Level 2 specifies at 40 CFR
63.1063(d)(1)(v) that a gap of more than \1/8\ inch between any deck
fitting gasket, seal or wiper, and the surface that it is intended to
seal is an inspection failure. The Generic MACT for Tanks Level 2 does
not, however, explicitly specify how an inspector is to determine
whether gaps exceed this amount. Therefore, we are proposing to specify
in proposed 40 CFR 65.315(c)(2)(i) that an inspector must use a \1/8\-
inch diameter probe, and each location where the probe passes freely
constitutes a gap. This procedure is consistent with the currently
specified procedure for monitoring rim seal gaps in EFR tanks.
    Third, we are proposing an editorial change to the language from 40
CFR 63.1063(d)(1)(v) that is incorporated in

40 CFR 65.315(c)(2)(i). In the Generic MACT for Tanks Level 2, 40 CFR
63.1063(d)(1)(v) specifies that the gap limit for deck fittings applies
to ``any deck fitting gasket, seal, or wiper.'' The use of the word
``seal'' in this sentence may be misinterpreted as meaning the
provision applies to rim seals because the design requirements for deck
fittings refer only to gaskets and wipers. Therefore, to eliminate
confusion and improve clarity, we are proposing in 40 CFR
65.315(c)(2)(i) to specify that the gap limit applies to each deck
fitting gasket or wiper.
    Fourth, to increase compliance flexibility and possibly emissions
reductions, we are proposing to allow optical gas imaging or monitoring
using Method 21 of 40 CFR part 60, appendix A-7 as an alternative to
measuring rim seal gaps for EFR and deck fitting gaps for both IFR and
EFR. The monitoring would be required on the same schedule as the
otherwise applicable gap measurement requirements. An inspection
failure would occur if you obtain an instrument reading greater than
500 ppmv when monitoring using Method 21 of 40 CFR part 60, appendix A-
7, or when you obtain an image of emissions when using optical gas
imaging. Conditions causing an inspection failure would have to be
repaired. To ensure consistent and reliable results when using optical
gas imaging, we are also proposing two additional requirements: (1)
Optical gas imaging would be allowed only if at least one compound in
the emissions from the storage vessel can be detected by the optical
gas imaging instrument and (2) monitoring would be required in
accordance with a new protocol for optical gas imaging. As discussed in
sections III.A.3 and III.A.4 of this preamble, we are currently
developing a protocol for using optical gas imaging instruments, and we
expect that the protocol will be proposed as appendix K in 40 CFR part
60. We anticipate that compliance with either of the proposed
monitoring alternatives would result in lower emissions than compliance
with the conventional gap measurement requirements because agency
personnel using an optical gas imaging instrument have often seen
images of emissions from seals and fittings that appear to be in good
condition upon visual inspection (see the memorandum titled Leaks
Observed from Fixed Roof and Floating Roof Fittings, in the docket for
proposed subpart I). We have not estimated cost effectiveness to
conduct optical gas imaging or monitoring using Method 21 of 40 CFR
part 60, appendix A-7, because such monitoring is only an alternative
to gap measurements, not a requirement. However, monitoring costs and
burden for optical gas imaging may be lower if several fittings can be
monitored simultaneously. We request comment on the technical
feasibility, performance and costs of both proposed alternatives to gap
measurement requirements.
    Fifth, we are proposing to require inspections of an EFR deck and
fittings annually rather than at least every 10 years, as specified in
the Generic MACT for Tanks Level 2. The Generic MACT for Tanks Level 2
requires annual secondary seal gap measurements, but complete
inspections of the EFR, rim seals and deck fittings are required only
when the storage vessel is completely emptied and degassed, or every 10
years, whichever occurs first. A commenter on the proposed changes to
storage vessel requirements in 40 CFR part 63, subpart CC (73 FR 66694,
November 10, 2008), which would have referenced the Generic MACT for
Tanks Level 2, stated that the annual inspection for EFR should be
expanded to include inspection of the roof and deck fittings as well as
the secondary seal because defects in the roof or fittings are often
clearly visible during the secondary seal inspections (see Docket Item
No. EPA-HQ-OAR-2003-0146-0176). Furthermore, the commenter noted that,
under the current rule, it is unclear whether any such defects noted
during the annual inspection are to be repaired, reported or ignored
until the next complete inspection. Upon review, we have determined
that annual inspections of the EFR deck and fittings are reasonable
because: (1) An inspection for other failures can readily be
accomplished each time an inspector is measuring secondary seal gaps;
(2) conducting such failure inspections annually would more closely
align the EFR inspection requirements with the current IFR inspection
requirements; and (3) we estimated the additional burden and costs to
be minimal. Measurement of gaps between deck fitting gaskets and the
surfaces they are intended to seal is not required for IFR. However,
given that EFR have a greater potential for emissions due to wind
effects, we think the minimal additional time and cost to perform such
measurements of EFR fittings is reasonable in light of the potential
for reduced emissions. We estimated the additional labor costs for
visual inspections, measurement of deck fitting gasket gaps and
associated recordkeeping to be about $100/year. The additional burden
was estimated to be about 2 hours per storage vessel.
    As noted above, we are proposing to allow monitoring using Method
21 of 40 CFR part 60, appendix A-7 and optical gas imaging as
alternatives to gap measurement requirements. We estimated the costs
and burden to conduct annual monitoring of EFR deck fittings using
Method 21 of 40 CFR part 60, appendix A-7 to be about the same as for
annual to measurement of gaps at each fitting because an inspector has
to check each fitting individually in both cases. Theoretically, costs
and burden to conduct optical gas imaging could be slightly less
(assuming the facility is using a camera that has already been
purchased for monitoring equipment leaks) because several emission
points can be monitored simultaneously with an optical gas imaging
instrument, but we assumed the same amount of time because time is
needed to prepare the camera and to obtain images from multiple
locations. See the memorandum titled Survey of Control Technology for
Storage Vessels and Analysis of Impacts for Storage Vessel Control
Options, in the docket for proposed subpart I for additional discussion
of how these costs and burden estimates were developed. We request
comments that assess the effectiveness and burden of the proposed
annual EFR inspections relative to the inspection requirements in the
Generic MACT for Tanks Level 2.
    We are also proposing to clarify that repair is required any time a
condition that constitutes an inspection failure is noted, regardless
of whether it was noted as part of a scheduled inspection. Although not
stated explicitly, current rules imply that repair is required any time
an inspection failure is noted because they state that inspections must
be conducted at least once during a specified time period. Any time a
condition that constitutes an inspection failure is noted is
effectively an inspection, whether or not it was scheduled.
    Finally, we are proposing changes to clarify the required frequency
of inspections because we received comments on proposed amendments to
40 CFR part 63, subpart CC, that the current requirements could be
subject to different interpretations (see docket item EPA-HQ-OAR-2003-
0146-0176). For example, the requirement to conduct inspections ``every
10 years'' could mean in every tenth calendar year, no later than the
date 10 years after the previous inspection or in the same month every
10 years. The same uncertainties also apply to the inspection
requirements that must be

conducted once per year or every 5 years. We have also been asked when
the inspection must be conducted if the storage vessel is out of
service on the date when the inspection must be completed. To address
these questions, we are proposing to replace the requirements for
inspections at least once per year with a requirement to conduct
inspections at least annually. The proposed General Provisions in 40
CFR part 65, subpart H specify that ``annually'' means once per
calendar year, and successive occurrences of such events must be
separated by at least 120 days. For the inspections that are required
at least every 5 years and every 10 years under the Generic MACT for
Tanks Level 2, we are proposing to require that the inspection
typically must be conducted before the date 5 years (or 10 years) after
the last inspection. The only exception is that an inspection may be
delayed if the storage vessel is out of service on that date, but in
such cases, the inspection must be conducted before the storage vessel
is refilled.
    Repairs. The proposed requirements to repair conditions that caused
inspection failures are similar to the requirements at 40 CFR
63.1063(e) in the Generic MACT for Tanks Level 2. We are proposing
three changes to clarify the requirements. As discussed above, the
first change clarifies that all conditions that cause an inspection
failure, regardless of whether they were identified during a scheduled
inspection, must be repaired.
    The second change would clarify terminology. The applicable repair
requirements in 40 CFR 63.1063(e) differ depending on whether or not
the inspection was conducted while the storage vessel was storing
liquid. These requirements could be subject to inconsistent
interpretations because the term ``storing liquid'' is not defined in
the rule. The intent of the language was to apply different procedures
depending on whether or not the storage vessel was completely empty
when the inspection was conducted. The term ``completely empty'' is
defined in the rule. Therefore, rather than define ``storing liquid,''
we are proposing to replace that term with the term ``completely
empty'' to clarify the requirements.
    The third change would clarify the recordkeeping requirements when
you use an extension to delay repair or emptying of a storage vessel
beyond 45 days. The current requirements in 40 CFR 63.1063(e) imply
that documentation of extensions is to be prepared before you use an
extension and could be misinterpreted as requiring a request for
approval to use an extension. Section 63.1067 of the Generic MACT for
Tanks Level 2 also specifies that this documentation be submitted in
periodic reports. We have determined that approvals are not necessary;
records that document the type of failure, the reasons why an extension
was needed, the steps taken to either repair or completely empty the
storage vessel during the extension and the date on which repairs were
completed or the storage vessel was completely emptied are sufficient
to demonstrate compliance. Furthermore, requesting approval via a
periodic report is impractical because the schedule of such reports is
unlikely to coincide with many extension periods. Therefore, to clarify
the reporting requirements, the language in the proposed rule differs
from the Generic MACT for Tanks Level 2 in that it clearly requires
records of each decision to use an extension.
5. How did the EPA determine the proposed requirements for vapor
balancing as a compliance approach for atmospheric storage vessels?
    We are proposing that the second approach for atmospheric storage
vessels is vapor balancing (proposed 40 CFR 65.320). Proposed subpart I
would require the same design, operating, monitoring and repair
requirements for the fixed roof and closure devices that would be
required for the closed vent system approach. See section III.B.6 of
this preamble for a discussion of our rationale for these requirements.
The vapor balancing requirements that we are proposing are similar to
requirements in several rules in 40 CFR part 63 (e.g., the MON), except
for the following three changes. First, we are proposing to replace the
requirement to conduct quarterly monitoring of pressure relief valves
on storage vessels using Method 21 of 40 CFR part 60, appendix A-7,
with a requirement to conduct applicable LDAR requirements for all
equipment in the vapor balancing system. The proposed requirements are
nearly identical to the proposed requirements for closed vent systems,
as described in section III.B.6 of this preamble. The only difference
is that you would have the option to reduce instrument monitoring
frequencies (for types of equipment that must be monitored) consistent
with the alternative for equipment in batch operations in proposed 40
CFR part 65, subpart J. We proposed this difference because it would be
possible to determine the total operating hours for a vapor balancing
system, but not for a closed vent system. We are not proposing to limit
the monitoring requirement to PRD because such monitoring provides
information only for that one piece of equipment. Conducting monitoring
of the entire vapor balancing system while the storage vessel is being
filled provides more information about the integrity of the entire
system, and it is information collected while the system is actually
operating and most likely to be emitting vapors.
    The second difference from vapor balancing requirements in current
rules is that the proposed rule would require design, operation,
inspection and repair of openings and closure devices consistent with
the requirements for fixed roofs in storage vessels that are controlled
by routing emissions through a closed vent system to a control device,
as described in section III.B.6 of this preamble. Although current
rules and proposed subpart I require PRD be set at levels to prevent
breathing losses, we determined that additional requirements are needed
to minimize vapor leakage through the roof and fittings regardless of
the method for controlling breathing and working losses.
    The third difference from vapor balancing requirements in current
rules is that the proposed rule would specify no requirements for
offsite facilities that reload (and in some cases clean) the transport
vehicle or barge. In current rules, these facilities are subject to the
same control requirements as the facility that has the affected storage
vessel. Both the vapor balancing and closed vent system options were
included in current rules in 40 CFR part 63 because they were
determined to be at least as effective as using floating roofs, which
represented the MACT floors. Based on recent analyses, we determined
that requiring control of offsite facilities as part of a vapor
balancing option results in better overall control than the other
options. Furthermore, the total emissions from a regulated source
implementing vapor balancing and an uncontrolled offsite cleaning/
reloading facility typically are about the same as the total emissions
from both facilities when the regulated source implements the closed
vent system approach. The performance of the closed vent system
approach relative to vapor balancing will vary depending on the
saturation level of the vapor space in the transport vehicle or barge
when unloading of liquid to the storage vessel is complete. If the
organic compound concentration in the vapor space of the transport
vehicle or barge when transfer is complete is approximately the same as
the concentration in the vapor space of the storage vessel, then the
total mass of organic compounds in the transport

vehicle or barge (in both the vapor space and the liquid heel) would be
the same under both approaches. Under these conditions, the performance
of the two approaches is essentially the same, and control at the
offsite cleaning/reloading facility as part of the vapor balancing
approach is not needed to achieve the same level of control as the
closed vent system approach. See the memorandum titled Vapor Balancing
Emissions Estimates for Storage Vessels, in the docket for proposed
subpart I for example calculations.
    Another issue with the vapor balancing approach, as specified in
current rules, is that it imposes a significant burden on the offsite
facilities (assuming these facilities are not required to control
transfer operations emissions under a rule that currently applies to
their source category). Furthermore, because facilities outside the
United States are not required to comply with this rule, a regulated
source would not be allowed to use the vapor balancing approach if the
transport vehicle is cleaned outside of the United States. Therefore,
we have decided not to include control requirements for offsite
facilities in proposed subpart I because we have determined that such
requirements result in greater overall emissions reductions than other
storage vessel control approaches. This additional control is not
needed to meet regulatory requirements such as MACT in current rules
because the performance of vapor balancing without offsite control is
at least equivalent to the performance of other control approaches,
including those that represent MACT in current rules. As a result, the
offsite control requirement also imposes an unnecessary burden on the
offsite facilities. Furthermore, the vapor balancing approach without
offsite controls imposes clearly enforceable requirements on the
regulated facility. We request comment on the differences between the
proposed vapor balancing requirements and the vapor balancing
requirements in current rules. In particular, we are interested in
whether the proposed lack of requirements for offsite facilities could
result in significantly higher total emissions under some conditions.
We are also interested in test data or theoretical calculations of the
organic compound saturation level or concentration in the vapor space
of freely vented transport vehicles at the time when unloading of
various liquids is complete.
6. How did the EPA determine the proposed requirements for control of
atmospheric storage vessels when routing emissions through a closed
vent system to a control device?
    As discussed in section III.A.5 of this preamble, the proposed
requirements are based on a combination of the procedures specified in
40 CFR part 65, subpart M and several additional requirements. As
discussed in section V.B of this preamble, we have structured the
proposed requirements in subpart M to be applicable to any emissions
stream that is controlled by routing through a closed vent system to a
control device. Referencing these provisions from proposed subpart I
promotes consistency for all emissions streams that are routed through
a closed vent system to a control device. It is also intended to
simplify and reduce the burden of compliance and reduce the potential
for inadvertent errors. However, we are also proposing several
additional requirements to ensure appropriate control for storage
vessels.
    In addition to the proposed requirements in 40 CFR part 65, subpart
M, we are proposing to require design and operation of the fixed roof
and closure devices consistent with the proposed requirements for fixed
roof storage vessels, as discussed in section III.B.3 of this preamble,
except that breathing and working losses would have to be controlled
rather than vented to the atmosphere. We are also proposing to require
the same type of monitoring and repair of all potential sources of
vapor leakage from the fixed roof and closure devices, as discussed in
section III.B.3 of this preamble. We request comment on whether the
proposed monitoring frequencies are reasonable and if any changes to
operating procedures for the monitoring devices would ensure that the
alternative monitoring methods provide similar results.
    For equipment in a closed vent system, proposed 40 CFR part 65,
subpart M references the compliance requirements in proposed 40 CFR
part 65, subpart J. However, in subpart I we are proposing to reference
only the bypass line requirements in proposed subpart M and reference
directly the applicable equipment leak requirements in proposed subpart
J. We selected this approach to specify more easily that certain
options in proposed subpart J do not apply to equipment in a closed
vent system that conveys emissions from a regulated storage vessel.
Specifically, the alternative monitoring frequency requirements for
equipment in batch operations would not be allowed for equipment in
such closed vent systems because the closed vent system must be in
service continuously. Similarly, the provision that specifies sensory
monitoring for equipment in service less than 300 hr/yr would not be
allowed for equipment in such closed vent systems because determining
the amount of time the system actually is conveying emissions is not
practical.
    The applicable requirements in 40 CFR part 65, subpart J differ
depending on whether the equipment is in regulated material service or
if it contains or contacts fluid that contains regulated material at
levels below the regulated material service threshold. Current rules
typically require sensory monitoring of closed vent systems (only
closed vent systems constructed of ductwork are subject to monitoring
using Method 21 of 40 CFR part 60, appendix A-7). We are proposing
instrument monitoring of closed vent systems in regulated material
service to be consistent with the requirements for process lines that
convey gaseous materials and to ensure that the emission streams reach
the control device so that the required level of control is met. As an
alternative to using Method 21 of 40 CFR part 60, appendix A-7, we are
proposing to allow monitoring using an optical gas imaging device
(after the protocol is promulgated, as discussed in section III.A.3 of
this preamble), provided at least one compound in the emissions can be
detected by the optical gas imaging instrument.
    The proposed rule also specifies that all equipment in sections of
closed vent systems that convey emissions from storage vessels that
meet the thresholds for control (i.e., the thresholds specified in
Table 1 of this preamble) are in regulated material service; no
additional determination of the composition of gas streams in the
closed vent system is required. This approach is being proposed because
it provides an easy way for determining when equipment is in regulated
material service and because the concentration of organic compounds in
vapor that is in equilibrium with a liquid that has a vapor pressure of
0.75 psia (the minimum threshold for control) is approximately 50,000
ppmv, which after conversion to a weight basis, is comparable to or
lower than typical 5 percent or 10 percent by weight thresholds in
definitions of ``in organic HAP service'' or ``in VOC service'' in
current rules. We request comment on other approaches that can
accurately determine whether equipment is in regulated material service
without imposing unreasonable burden.

    Current rules for storage vessels generally require non-flare
control devices to reduce organic compound emissions by at least 95
percent or to an outlet concentration of regulated material less than
20 ppmv. They also require at least a 99-percent reduction or outlet
concentration less than 20 ppmv for acid gases or halogen atoms (the
acid gases may be part of the emission stream directly from the storage
vessel, or they may be generated by burning halogenated organic
compounds in combustion control devices). These levels are achievable
by storage vessels storing a wide range of materials in a wide range of
source categories, and they are at least equivalent to the reductions
that are achieved when using floating roofs. Thus, we are proposing to
specify these required control levels in proposed subpart I rather than
in each of the individual referencing subparts, thereby improving
consistency and simplifying the referencing subparts. The use of flares
to control organic emissions from storage vessels is another option
that would be allowed in proposed subpart I; all requirements for
flares are covered in 40 CFR 63.11(b) of subpart A.
    Proposed 40 CFR part 65, subpart M specifies that control
performance requirements will be specified in referencing subparts.
Because proposed subpart I specifies the required reductions or outlet
concentrations for non-flare control devices used to control emissions
from storage vessels, subpart I (rather than the rule that references
subpart I) would be the referencing subpart for the purpose of
complying with proposed subpart M. Therefore, subpart I must specify
the provisions for initial compliance determinations (i.e., design
evaluation or performance test), if applicable for storage vessels. We
determined that design evaluations provide sufficiently accurate
results for demonstrating compliance with the reductions required for
storage vessels. Thus, we are proposing to specify in subpart I that
initial compliance with requirements for non-flare control devices that
control emissions from storage vessels may be demonstrated using a
design evaluation instead of a performance test, which is the default
in subpart M. However, any control devices that control other emissions
(e.g., process vents) in addition to storage vessel emissions, may
still be required to conduct a performance test instead of a design
evaluation, if another subpart references subpart M for the same
control device.
    As in current rules, we are proposing to require different
standards for periods of planned routine maintenance of the control
device. We are not proposing to require compliance with the same
standard at all times because the cost of such a requirement would be
unreasonable. Instead, we are proposing to prohibit the addition of
material to the storage vessel during periods of planned routine
maintenance and to limit the time of planned routine maintenance to
less than 360 hr/yr. If you need more than 240 hr/yr, you would be
required to keep a record documenting why 240 hours is insufficient and
the steps you took to minimize the additional time for planned routine
maintenance. In analyses for current rules, 240 hours has been
determined as sufficient for most control device rebuilds.
7. How did the EPA determine the proposed requirements for control of
atmospheric storage vessels when routing emissions to a fuel gas
system?
    For fuel gas systems that control emissions from storage vessels,
proposed subpart I references the fuel gas system requirements in
proposed 40 CFR part 65, subpart M and specifies a few additional
requirements to ensure appropriate control for storage vessels. See
section V.B.4 of this preamble for a discussion of the requirements in
subpart M for fuel gas systems. Proposed subpart I also would require
the same design operating, monitoring and repair requirements for the
fixed roof and closure devices that would be required for the closed
vent system approach. See section III.B.6 of this preamble for a
discussion of our rationale for these requirements. Proposed subpart I
also would require compliance with proposed 40 CFR part 65, subpart J
for the equipment in the fuel gas system. As for the closed vent system
approach, all equipment in sections of a fuel gas system that convey
emissions from an affected storage vessel are in regulated material
service and subject to the monitoring and other LDAR requirements for
equipment in regulated material service. See section III.B.6 of this
preamble for a discussion of the rationale for these requirements.
8. How did the EPA determine the proposed requirements for control for
pressure vessels?
    A pressure vessel is defined in the Uniform Standards as a storage
vessel that is designed not to vent to the atmosphere as a result of
compression of the vapor headspace in the vessel during filling of the
vessel. We are proposing standards for all pressure vessels that
contain any regulated material. We are not proposing thresholds for the
following reasons. First, materials stored in a pressure vessel are
likely to be highly volatile; thus, a low vapor pressure threshold
would have little or no impact. Second, we do not expect the operating
pressure or frequency of leaks to vary with the size of the storage
vessel. Thus, the emissions for the same emission pathway would be the
same regardless of the size of the storage vessel. Third, the fittings
on the pressure vessel are comparable to the types of equipment (and in
the same service as equipment) that would be subject to monitoring
under proposed 40 CFR part 65, subpart J.
    The proposed requirements for pressure vessels are to equip each
opening with a closure device, operate without emissions to the
atmosphere at any time, monitor annually all potential leak interfaces
using Method 21 of 40 CFR part 60, appendix A-7 (or semiannually when
using optical gas imaging), estimate and report emissions from periods
when instrument readings exceed 500 ppmv or an image is detected and
route purge streams to a control device. Closure devices are an
operational necessity for pressure vessels, and they prevent emissions
as well. We are proposing periodic monitoring requirements as a means
to demonstrate compliance with the requirement to operate without
emissions to the atmosphere. We have determined that estimating and
reporting emissions is needed to help inform decisions about where to
target compliance inspections and to ensure that the pressure vessels
are properly operating with no vents to the atmosphere. The burden to
conduct monitoring and associated recordkeeping and reporting is
estimated to be about 2 hr/yr per storage vessel, at a cost of about
$170/year for monitoring with Method 21 of 40 CFR part 60, appendix A-
7. The burden is estimated to be about 3.5 hr/yr at a cost of about
$260/year for monitoring with an optical gas imaging instrument. The
differences in the proposed Uniform Standards are due primarily to the
different monitoring frequencies.
    We are proposing to include an alternative to the requirement of
maintaining a closed system at all times. This alternative would allow
you to purge inert materials that build up in the pressure vessel,
provided the purge stream is routed through a closed vent system to a
control device that achieves the same performance that is being
proposed for atmospheric storage vessels (i.e., reductions of at least
95 percent or to less than 20 ppmv or routed to a flare that meets the
requirements in 40 CFR 63.11(b)). This

provision is consistent with an option for controlling emissions from
pressure vessels that manage hazardous waste and are subject to the
Standards for Owners and Operators of Hazardous Waste Treatment,
Storage, and Disposal Facilities in 40 CFR 264.1084 and 40 CFR
265.1085. We are proposing this option in subpart I because it is
consistent with and ensures control comparable to proposed requirements
for atmospheric storage vessels.
9. How did the EPA determine the proposed requirements for overfill
detection and alarms?
    We are proposing to require you to equip each storage vessel with
an overfill detection sensor. A consortium of international oil
companies conducted a study that concluded 11 percent of sunken-roof
accidents were caused by overfilling the storage vessel (see 2008
American Petroleum Institute (API) AST Conference, in the docket for
proposed subpart I). According to instrumentation industry
representatives, overfill detection systems are currently available,
and storage vessels designed to American Society of Mechanical
Engineers (ASME) standards must be equipped with such monitoring and
alarm systems. The proposed overfill monitoring requirement is intended
to alert you to a potential overfill so that you can take action to
prevent the overfill and, thus, avoid a deviation of design
requirements. We estimated the average cost to plan, purchase and
install the required monitor and alarm to be about $1,900 per storage
vessel. We estimated the average annual cost of the proposed
requirement, including recordkeeping and reporting, to be about $400/
year per storage vessel. We expect that this requirement will add
little burden because we understand that most storage vessels are
already equipped with overfill monitoring and alarm systems. Therefore,
we request comment with descriptions of any types of affected storage
vessels that are not already equipped with overfill protection systems.
We also request comment on whether additional design or operational
requirements are needed to ensure successful implementation and
enforcement of the proposed overfill monitoring requirement, and
whether other types of monitoring could better prevent overfill and the
resulting emissions.
10. How did the EPA determine the proposed requirements for control of
transfer operations to load transport vehicles?
    In the survey of technology for control of transfer operations that
involve loading transport vehicles, we identified several compliance
approaches. The most common is submerged loading (or bottom loading).
We identified this compliance approach as Control Option TR1. We also
identified four additional compliance approaches that are more
effective than submerged loading alone: (1) Control Option TR2 is to
route displaced emissions through a closed vent system to a flare; (2)
Control Option TR3 is to route displaced emissions through a closed
vent system to a control device that reduces regulated organic
emissions by at least 98 percent or to less than 20 ppmv; (3) Control
Option TR4 is to vapor balance the displaced emissions back to the
storage vessel from which the transport vehicle is being loaded; and
(4) Control Option TR5 is to route displaced emissions to a fuel gas
system.
    We estimated impacts only for Control Options TR1 and TR2. We did
not estimate impacts for the other compliance approaches for several
reasons. We did not estimate costs for Control Option TR3 because, as
part of the analysis for the OLD NESHAP, we determined that flares are
the most common and least costly control device for transfer racks. See
the memorandum titled Environmental and Cost Impacts of the Proposed
OLD NESHAP, in docket item EPA-HQ-OAR-2003-0138-0053 for the flare
analysis. Although vapor balancing may be less costly than control
using a flare in some cases, we did not estimate impacts for Control
Option TR4 because vapor balancing requires no venting from the system
while a transfer is occurring. This will require pressure settings in
the system that may not be feasible for some atmospheric storage
vessels. We also did not estimate impacts for Control Option TR5
because not all facilities have or could make use of a fuel gas system,
and it would be impractical to install a fuel gas system to handle
transfer emissions alone.
    Regardless of the control option, vapor tightness testing of the
transport vehicle is an approach for ensuring that emissions are
conveyed to the intended destination. Finally, LDAR for the equipment
in the transfer rack is an approach for controlling fugitive emissions
from the transfer rack itself. Each of the control options and other
compliance approaches and how they have been incorporated into proposed
subpart I are discussed in the sections below.
    Control Option TR1. According to AP-42 Chapter 5.2, splash loading
results in a vapor-space saturation factor of 1.45, and submerged
loading results in a saturation factor of 0.6. Reducing the saturation
factor also reduces the concentration of organic compounds in the gases
that are displaced when loading the transport vehicle. Thus, Control
Option TR1 reduces transfer emissions by an estimated 60 percent
relative to splash loading. As shown in Table 7 of this preamble, the
costs for Control Option TR1 in light of the estimated emissions
reductions also are reasonable for a wide range of transfer throughputs
and average vapor pressures. In many cases, the switch to submerged
loading would result in a cost savings. Thus, we are proposing that all
transfers of regulated material to transport vehicles be conducted
using submerged (or bottom) loading.

                     Table 7--Estimated Impacts for Submerged Loading of Transport Vehicles
                                              [Control option TR1]
----------------------------------------------------------------------------------------------------------------
                                Total transfer
                                 throughput at                                     Emission        Incremental
   Average vapor pressure of       facility        Number of     Total annual    reduction \a\        cost
 transferred material  (psia)    (million gal/   loading arms    costs  ($/yr)       (tpy)        effectiveness
                                      yr)                                                         \a\  ($/ton)
----------------------------------------------------------------------------------------------------------------
0.08..........................               2               1             710            0.13             5,400
0.08..........................              21               4           2,100            1.4              1,500
0.08..........................              45              12           7,300            2.9              2,500
1.............................               2               1             190            1.6                100
1.............................              21               4        (12,100)           17                (710)
1.............................              45               6        (28,000)           37                (770)
3.............................               2               2         (2,700)            4.9              (560)
3.............................              21               4        (43,000)           51                (840)

3.............................              45               6        (94,000)          110                (860)
----------------------------------------------------------------------------------------------------------------
\a\ Relative to uncontrolled (i.e., splash loading).

    The emissions estimates for the model facilities in Table 7 of this
preamble were estimated using procedures in AP-42 Chapter 5.2, assuming
the average transfer temperature is 60[emsp14][deg]Farenheit and the
average vapor molecular weight of transferred materials is 80. The
total capital investment was scaled from a quote for converting a rack
that has six arms from splash loading to submerged loading; this quote
was provided by an industry trade association during development of the
gasoline distribution area source rule (see docket item EPA-HQ-OAR-
2006-0406-0060). Annual costs were developed for operation, maintenance
and indirect costs such as capital recovery. We also included a product
recovery credit for the emissions prevented by the change in loading
procedures. See the memorandum titled Survey of Control Technology for
Transfer Operations and Analysis of Impacts for Transfer Operation
Control Options, in the docket for proposed subpart I for additional
information regarding the development of these impacts.
    Control Option TR2. In the impacts analysis for Control Option TR2,
we evaluated the impacts for model facilities similar to those that we
used in the analysis of submerged loading impacts. The resulting annual
costs, emission reductions and incremental cost effectiveness relative
to Control Option TR1 are shown in Table 8 of this preamble. See the
memorandum titled Survey of Control Technology for Transfer Operations
and Analysis of Impacts for Transfer Operation Control Options, in the
docket for proposed subpart I for a more detailed discussion of how the
impacts were developed.

  Table 8--Estimated Impacts To Control Emissions From Loading of Transport Vehicles Using a Closed Vent System
                                                    and Flare
                                              [Control option TR2]
----------------------------------------------------------------------------------------------------------------
                                Average vapor
                                 pressure of                                       Emission     Incremental cost
 Total transfer throughput at    transferred      Number of     Total annual    reduction \a\     effectiveness
  facility  (million gal/yr)      material      loading arms    costs  ($/yr)       (tpy)         \a\  ($/ton)
                                   (psia)
----------------------------------------------------------------------------------------------------------------
15...........................               1               6          94,000              8.5            11,100
                                            3               2          79,000             25.4             3,100
                                            6               6          94,000             50.7             1,900
25...........................               1              10         116,000             14.1             8,200
                                            3               8         104,000             42.3             2,500
                                            6               8         104,000             84.5             1,200
45...........................               1               6          94,000             25.4             3,700
                                            3               6          94,000             76.1             1,200
                                            6              12         131,000            152                 860
----------------------------------------------------------------------------------------------------------------
\a\ Relative to submerged loading.

    Based on the results in Table 8 of this preamble, we determined
that the costs of Control Option TR2 are reasonable when a facility
transfers more than 35 million gal/yr of liquids that contain regulated
material, and the weighted-average vapor pressure of the transferred
liquids is a little over 3 psia. Using the monthly temperature data in
AP-42 Chapter 7.1 to calculate vapor pressures for several cities shows
the average true vapor pressure often is about 80 percent of the MTVP.
Thus, we are proposing to require control of displaced emissions from
transport vehicle loading at facilities that meet thresholds of at
least 35 million gal/yr throughput and a weighted average MTVP of at
least 4 psia.
    As for storage vessels, some current rules specify thresholds for
transfer operation control that are more stringent than the thresholds
that we determined to be cost effective. For transfer operations, we
decided not to propose any of the thresholds from current rules because
few current rules require control of transfer operations, and the
thresholds in these rules vary. We also have not conducted regulatory
analyses for source categories that do not have control requirements
for transfer operations. Therefore, we do not know what thresholds
would be appropriate in those rules if they were to be amended to
include requirements for transfer operations. At a minimum, the current
analysis identifies the cost-effective thresholds that could be used as
a starting point in more detailed analysis of requirements on a source
category-specific basis.
    In contrast to some current rules (e.g., the HON), the proposed
vapor pressure threshold is based on the MTVP instead of average vapor
pressure. This is intended to reduce the compliance burden. If the
temperature of the transferred material varies over the year, then
significant calculations and recordkeeping is needed to document the
vapor pressure for each transfer and the average over all transfers
during the year. The burden grows as the number of materials
transferred increases. We recognize that even determining the
throughput-weighted MTVP could be burdensome for a rack that transfers
numerous regulated materials. It also

requires you to project the total amount of various materials that you
expect to transfer during the year so that you can determine whether
there is a chance that you would exceed the thresholds. Basing the
control threshold only on throughput as in some rules (e.g., the OLD
NESHAP) would be less burdensome, but control would be required
regardless of the material transferred. Therefore, we request comment
on the proposed thresholds for control and suggestions for alternative
thresholds that would impose less compliance burden while still
ensuring control of emissions when the cost of such control is
reasonable.
    Other compliance approaches. We are proposing to include several
alternative compliance options with which you may elect to comply
instead of using a flare. These alternatives are based on Control
Options TR3, TR4 and TR5, and they are being included because their
performance is the same as or possibly marginally better than the
performance obtained by routing emissions through a closed vent system
to a flare. We are proposing compliance procedures based on Control
Options TR3 and TR5 that are the same as for the closed vent system and
fuel gas system approaches for control of storage vessel emissions,
except that monitoring or inspections would be required while a
transport vehicle is being filled with regulated material. As in the
requirements for storage vessels, we are proposing to allow you to
demonstrate initial compliance with an emission limit using either a
design evaluation or performance test regardless of the throughput. We
are proposing this approach to minimize the compliance burden and
because we have determined a design evaluation is sufficient given the
relatively low level of emissions from transfer operations relative to
other emission sources.
    The option based on Control Option TR4 is similar to the vapor
balancing approach in the OLD NESHAP and other rules in that it
includes both design requirements and inspection requirements (e.g.,
see 40 CFR 63.2346 and Tables 7 and 10 in 40 CFR part 63, subpart
EEEE). Unlike current rules, however, we are also proposing to require
the following specific design elements and operating procedures: (1)
The vapor balancing system must be designed to prevent any regulated
material vapors collected at one transfer rack from passing to another
transfer rack; (2) all vapor connections in the system must be equipped
with closures that seal upon disconnect; and (3) PRD in the system must
remain closed while regulated material is loaded in the transport
vehicle. Meeting these requirements will help ensure that the vapors
displaced from loading transport vehicles with regulated materials are
returned to the storage tank from which the liquids being loaded
originated. The second and third requirements also are consistent with
proposed requirements for vapor balancing systems to control emissions
from storage vessels. Finally, we are proposing to require LDAR of
equipment in the vapor balancing system consistent with the proposed
requirements for equipment in closed vent systems. The vapor balancing
system monitoring requirements vary widely in current rules. For
example, no monitoring requirement is specified in the MON; the HON
requires either annual visual inspections or annual monitoring using
Method 21 of 40 CFR part 60, appendix A-7, depending on whether the
system is constructed of hard-piping or ductwork; and the OLD NESHAP
requires quarterly monitoring using Method 21 of 40 CFR part 60,
appendix A-7. We are proposing requirements consistent with those for
closed vent systems to streamline the compliance procedures and because
a vapor balancing system serves essentially the same purpose as a
closed vent system.
    Transport vehicle tightness testing. As part of the compliance
approaches that are based on Control Options TR2, TR3, TR4 and TR5, you
would be required to transfer regulated materials only to transport
vehicles that are determined to be vapor tight. We are proposing the
vapor tightness requirement for transport vehicles that are loaded at
affected transfer racks to ensure that the requirement to collect and
convey emissions to control during transfer operations is effective.
These requirements have the added benefit of minimizing emissions while
the vehicle is in transport as well. To be considered vapor tight, each
transport vehicle that is loaded with material that has a MTVP greater
than 4 psia would be required to pass an annual vapor tightness test
conducted using Method 27 of 40 CFR part 60, appendix A-8. All other
transport vehicles would be required to have a current certification in
accordance with DOT pressure test requirements in 49 CFR part 180 for
cargo tanks or 49 CFR 173.31 for tank cars. These proposed requirements
are similar to requirements in several current rules. For example,
several gasoline distribution rules require testing of gasoline
transport vehicles using Method 27 of 40 CFR part 60, appendix A-8
(e.g., 40 CFR part 60, subpart XX, and 40 CFR part 63, subpart R). The
OLD NESHAP requires EPA Method 27 testing for transport vehicles that
are equipped with vapor-collection equipment, and other transport
vehicles must meet the DOT certification requirements. In the preamble
to the proposed OLD NESHAP, we noted that tank trucks in chemical
service typically are not equipped with vapor-collection equipment (63
FR 15682, April 2, 2002). Although we are uncertain whether vapor-
collection equipment is now more common on trucks used to transport
chemicals than it was 10 years ago, we think it is appropriate that all
vehicles used to transport materials with vapor pressure comparable to
the vapor pressure of gasoline should be subject to the same vapor
tightness requirements. The proposed MTVP threshold was set at 4 psia
because this is about the minimum MTVP for any grade of gasoline. We
request comment on the burden and costs of this proposed requirement to
conduct vapor-tightness testing using Method 27 of 40 CFR part 60,
appendix A-8. For example, we are interested in estimates of the number
of vehicles that would have to be retrofitted with vapor-collection
equipment, the costs of such retrofits and the fraction of the volume
transported in such vehicles that exceeds the 4-psia threshold. In
addition, since the MTVP of a given material varies depending on
location, we request comment on whether a threshold based on another
parameter would be easier to implement.
    Finally, as in current rules, you would be required to take actions
to assure that your closed vent system, vapor balancing system or fuel
gas system is connected to the transport vehicle's vapor-collection
equipment when regulated material is transferred. These requirements
are intended to ensure that the displaced emissions are routed to the
required control. Examples of actions to satisfy this requirement
include training drivers in the hookup procedures and posting visible
reminder signs at the affected transfer racks.
11. How did the EPA determine the proposed requirements for control of
transfer operations to load containers?
    In the survey of technology of emission controls for transfer racks
that are used to load containers, we identified several control
approaches that have each been included in one or more current rules.
For example, one approach is to use controls such as submerged loading
or fitted openings in conjunction with transfer line purging. We also
identified operational practices to control emissions from containers
that are storing transferred regulated

material (e.g., maintaining covers and other closure devices in the
closed position except when access to the container is necessary). We
also identified three more effective compliance approaches: (1) Vapor
balance displaced emissions back to a storage vessel; (2) locate the
transfer rack inside an enclosure that meets the requirements for a
Permanent or Temporary Total Enclosure in 40 CFR 52.741, appendix B,
and exhaust the enclosure through a closed vent system to a control
device; and (3) vent displaced emissions from the container itself
through a closed vent system to a control device. In addition, vapor
tightness testing can be conducted on containers, like transport
vehicles.
    For the impacts analysis, we evaluated two control options: Control
Option TR6, which combines submerged fill with the operational
practices of using closure devices on stored containers and Control
Option TR7, which consists of venting displaced emissions through a
closed vent system to a flare. We did not estimate impacts for the
enclosure approach (Control Option TR8) because costs for the enclosure
are expected to result in higher total costs than for Control Option
TR7, and the control device might have to be larger to handle the
airflow needed to meet the requirements in 40 CFR 52.741, appendix B.
We did not estimate impacts for the vapor balancing approach (Control
Option TR9) because we are not aware of any facility that is using this
approach, and as with storage vessels, vapor balancing may not be
feasible at all facilities due to allowable pressure limits for safe
operation.
    The impacts of Control Options TR6 and TR7 for a series of model
transfer racks are presented in Table 9 of this preamble. The models
cover a range of typical throughputs as reported by facilities that
responded to an information collection request (ICR) for OLD operations
(see the memorandum titled Model Plants for the OLD Source Category, in
docket item EPA-HQ-OAR-2003-0138-0052 for site-specific throughputs).
The models also span a wide range of average vapor pressures.

       Table 9--Estimated Impacts of Control Options TR6 and TR7 for Loading Containers at a Transfer Rack
----------------------------------------------------------------------------------------------------------------
                                                               Total
                                                              transfer      Total
                                                             throughput     annual      Emission        Cost
Average Reid vapor pressure of transferred material (psia)  at facility   costs ($/    reduction   effectiveness
                                                              (million       yr)         (tpy)      \a\ ($/ton)
                                                              gal/yr)
----------------------------------------------------------------------------------------------------------------
                                               Control Option TR6
----------------------------------------------------------------------------------------------------------------
1.5.......................................................          0.1         700         0.016       43,000
1.5.......................................................            5         (13)         0.81          (16)
3.37......................................................          0.1         680         0.036       19,000
3.37......................................................            5        (920)          1.8         (510)
8.........................................................          0.1         630          0.12        5,500
8.........................................................            5      (3,200)        0.016         (550)
----------------------------------------------------------------------------------------------------------------
                                               Control Option TR7
----------------------------------------------------------------------------------------------------------------
1.5.......................................................          0.1      81,000         0.050    2,400,000
1.5.......................................................            5      81,000           2.5       47,000
3.37......................................................          0.1      81,000          0.11    1,100,000
3.37......................................................            5      81,000           5.6       21,000
8.........................................................          0.1      81,000          0.36      330,000
8.........................................................            5      81,000            18        6,600
----------------------------------------------------------------------------------------------------------------
\a\ Relative to uncontrolled for Control Option TR6 and relative to Control Option TR6 for Control Option TR7.

    Capital costs for submerged fill were estimated assuming the
capital costs for retrofitting one station that loads containers are
about half of the costs for retrofitting one arm that loads transport
vehicles. Annual costs for submerged fill were estimated using the same
procedures as in the analysis for Control Option TR1. Costs for the
closed vent and flare system were scaled from costs developed from
vendor information in the analysis for the OLD analysis (see docket
item EPA-HQ-OAR-2003-0138-0053).
    Uncontrolled emissions were estimated using two approaches. One
approach was to use the vehicle refueling equation presented in AP-42
chapter 5.2. This approach was used in the analysis for the OLD NESHAP
because surveyed OLD facilities were using nozzles like those used at
gasoline service stations. A problem with this approach is that it is
not reliable at low vapor pressures. Specifically, as the vapor
pressure approaches zero, the emissions are estimated to be negative.
Therefore, we also estimated emissions using a second approach, which
was to use the transfer rack loss equation in AP-42 chapter 5.2 (i.e.,
the same approach that we used to estimate emissions from transport
vehicles), but with one modification. It is not clear that the splash-
loading factor in AP-42 is applicable for container loading given the
much lower fill rate of containers. Therefore, we selected a saturation
factor (i.e., 0.88) that, when used in the transfer rack loss equation,
produced the same emissions as the vehicle refueling equation when the
Reid vapor pressure of transferred material is 3.37 psia (this is the
vapor pressure used for models in the OLD analysis). Using this factor
gave higher emissions estimates than the vapor refueling equation for
Reid vapor pressures lower than 3.37 psia, and it gave higher emissions
for Reid vapor pressures higher than 3.37 psia. To estimate controlled
emissions for Control Option TR6, we assumed the saturation factor
would be 0.6, as in the analysis for Control Option TR1. Thus, we
assumed Control Option TR6 reduces emissions by 32 percent ([0.88 -
0.6]/[0.88] = 0.32). Controlled emissions for Control Option TR7 were
assumed to be 2 percent of the emissions for Control Option TR6.
    The results of this analysis show the cost impacts for Control
Option TR6 are reasonable for throughputs greater than about 1 million
gal/yr over the range of vapor pressures specified for the model
transfer racks. The analysis also shows

the cost impacts of Control Option TR7 are unreasonable for all of the
same model transfer racks. Thus, for transfer operations that include
the loading of regulated material into containers, we are proposing
that the Uniform Standards require submerged loading. In addition, when
a loaded container contains regulated material and is maintained on
site, all openings in the containers would have to be equipped with
covers and closure devices, which you would have to maintain in the
closed position except when access to the container is necessary (e.g.,
for adding or removing material, sampling or cleaning).
    We are also proposing other options that have equal or better
performance that may be used instead of submerged loading, or that may
be required, if justified, by referencing subparts. These other options
include using fitted openings in conjunction with transfer line
purging, which is specified in the Gasoline Distribution NESHAP (40 CFR
part 63, subpart R). We are also proposing requirements for compliance
approaches that are based on Control Options TR8 and TR9. These
proposed requirements are a consolidated and streamlined version of the
requirements in the Generic MACT for Containers and OLD NESHAP. If you
use a closed vent system and control device, the control device would
be required to reduce regulated material emissions by 95 percent, as in
current rules. Inspection requirements for both closed vent systems and
vapor balancing systems would be the same as for such systems used to
convey emissions from loading of transport vehicles.
    If you load a container 55 gallons or larger with material that has
a MTVP greater than 4 psia and use the container for onsite storage of
that material, then the container would be subject to either annual
vapor tightness testing in accordance with Method 27 of 40 CFR part 60,
appendix A-8, or annual monitoring of potential leak interfaces using
Method 21 of 40 CFR part 60, appendix A-7. The leak definition for the
EPA Method 21 testing would be 500 ppmv. These testing or monitoring
requirements are needed to demonstrate that transferred materials with
high vapor pressures are not emitted from storage. We request comment
on the burden and costs of this proposed requirement to conduct vapor-
tightness testing using Method 27 of 40 CFR part 60, appendix A-8. For
example, we are interested in estimates of the number of containers
that would have to be retrofitted with vapor-collection equipment, the
costs of such retrofits and the fraction of the volume stored in such
containers that exceeds the 4-psia threshold. In addition, since the
MTVP of a given material varies, depending on location, we request
comment on whether a threshold based on another parameter would be
easier to implement.
12. How did the EPA determine the definitions of terms used in proposed
subpart I?
    As discussed in section VI.B.16 of this preamble, all definitions
are located in proposed 40 CFR part 65, subpart H. Most of the
definitions that are used in proposed subpart I are unchanged from the
definitions in current rules, such as 40 CFR part 63, subpart WW and
subpart EEEE. We are also proposing definitions for the terms
``barge,'' ``fittings'' and ``pressure vessel,'' which are not defined
in current rules. The vapor balancing requirements for storage vessels
specify that emissions from the storage vessel may be vapor balanced to
a barge that is providing the liquid to fill the storage vessel. To
clarify what type of vessel qualifies as a barge, we are proposing to
define a barge as ``any vessel that transports regulated material
liquids in bulk on inland waterways or at sea.''
    We are proposing to add a definition for the term ``storage
capacity.'' This term is intended to take the place of the term
``capacity'' that is defined in 40 CFR part 63, subpart WW. We are
proposing the change to avoid possible confusion because the term
capacity is also used in a different context in proposed 40 CFR part
65, subpart M. We are also modifying the definition to specify that
storage capacity of a flat-bottomed storage vessel is determined by
multiplying the internal cross-sectional area of the storage vessel by
the internal height of the shell, but the calculation for storage
vessels with a sloped bottom or cone-up or cone-down bottoms need to be
adjusted to account for the fact that the floor is not flat.
    We are proposing to include a definition for ``automatic bleeder
vent (vacuum breaker vent).'' Vacuum breaker vents equalize the
pressure across a landed floating roof when liquid is either being
withdrawn or added below the landed roof. Current rules do not include
a definition for such devices, but historically vacuum breaker devices
have been a covered well opening with a leg attached to the underside
of the cover. When the roof lands, the leg opens the vent by lifting
the cover off the well. Recently, we learned of a new design that is
activated by pressure or vacuum differences across the roof.
Theoretical calculations have shown such vents should open only while
the roof is landed, not while it is floating. Based on this analysis,
we have decided to include both mechanically activated and pressure/
vacuum activated devices in the proposed definition of ``automatic
bleeder vent (vacuum breaker vent).'' We request additional
information, in particular, any test data that either supports or
contradicts the theoretical analysis.
    Finally, we are proposing to use a new definition of ``maximum true
vapor pressure'' that excludes the list of methods that may be used to
determine MTVP. In proposed subpart I, this list has been moved to 40
CFR 65.306. We also added a new method to the list: Test Method for
Vapor Pressure of Reactive Organic Compounds in Heavy Crude Oil Using
Gas Chromatography. This method was developed because existing methods
cannot be applied to heavy crude oils. We moved the list of methods to
40 CFR 65.306 because we are also proposing three additional changes to
the procedures for determining MTVP that cannot be readily included in
a definition. First, we are proposing to require testing to determine
MTVP of mixtures (such as petroleum liquids) and to allow information
from reference texts to be used only for pure compounds. We are
proposing this change because we are concerned that the compositions of
mixtures (e.g., crude oils) vary considerably depending on their source
and how they are handled before storage. Thus, average or generic
values for a class of materials do not necessarily accurately represent
the characteristics of the material in each storage vessel. Second, we
are proposing to require new determinations each time a storage vessel
is filled with a different type of material. This is an implied
requirement in current rules, but this change clearly states the
requirement. Third, because the composition of mixtures can vary (as
noted above), we are proposing to require redetermination of the MTVP
annually if stored materials are mixtures and previous testing has
determined the MTVP is below the thresholds for control, as specified
in Table 1 of proposed subpart I (and Table 1 of this preamble).

IV. Summary and Rationale for the Proposed 40 CFR Part 65 National
Uniform Emission Standards for Equipment Leaks--Subpart J

A. Summary

    We are proposing new Uniform Standards for control of emissions
from equipment leaks. These Uniform Standards for equipment leaks would

apply only to equipment that is subject to a regulation that references
provisions in 40 CFR part 65, subpart J, for control of equipment
leaks. We would only issue regulations that reference provisions of 40
CFR part 65, subpart J, once we have determined that those provisions
meet applicable statutory requirements for a particular source category
(e.g., MACT, AMOS, BSER).
    In section IV of this preamble, the term ``we'' refers to the EPA
and the term ``you'' refers to owners and operators affected by the
proposed standards. Section IV.A.1 of this preamble identifies the
regulated sources under the proposed 40 CFR part 65, subpart J.
Sections IV.A.2 through 4 of this preamble summarize the proposed
standards for equipment leaks. Section IV.A.5 of this preamble
summarizes the proposed standards for using an optical gas imaging
instrument to detect leaks. Section IV.A.6 of this preamble summarizes
the notification, reporting and recordkeeping requirements. Section
IV.B of this preamble presents the rationale behind the development of
the proposed standards.
1. What parts of my plant are affected by the proposed rule?
    The proposed 40 CFR part 65, subpart J includes requirements for
equipment in process units, closed vent systems and fuel gas systems,
including valves, pumps, connectors, agitators, PRD, compressors,
sampling connection systems, open-ended valves and lines,
instrumentation systems and any other types of equipment specified by
the referencing subpart that contain or contact regulated material (as
defined by the referencing subpart). This subpart also includes
requirements for closed-purge and closed-loop systems used to control
emissions from certain types of equipment. Proposed 40 CFR part 65,
subpart J does not include applicability provisions; instead, the
referencing subpart would define what equipment in that source category
is subject to the provisions of the Uniform Standards.
2. What are the proposed general requirements for complying with this
subpart?
    Your equipment would be subject to some or all of the requirements
of 40 CFR part 65, subpart J when another subpart references the use of
provisions of subpart J for air emission control. In addition, you
would be required to meet the general provisions applicable to part 65
(i.e., subpart H of 40 CFR part 65) and the general provisions
applicable to the referencing subpart (i.e., subpart A of 40 CFR parts
60, 61 or 63).
3. What are the types of techniques we are proposing to reduce
emissions from equipment leaks?
    Equipment leak standards consist of techniques to detect leaks
based on sensory inspections, instrument monitoring or use of an
optical gas imaging instrument, as applicable. Equipment design
standards specify requirements regarding the use, design or operation
of the equipment. Each of these techniques is summarized in this
section.
    Sensory monitoring. Sensory monitoring includes visual, audible,
olfactory or any other sensory detection method used to determine a
potential leak to the atmosphere. If you found indications of a
potential leak, you would be required either to: (1) Repair the
equipment such that the indications of a potential leak to the
atmosphere are no longer evident; (2) determine that no bubbles are
observed at potential leak sites during a leak check using a soap
solution; or (3) conduct instrument monitoring as described in the next
paragraph to determine if the instrument reading is above the
applicable threshold (indicating that the equipment is leaking) and, if
the equipment is leaking, repair the leak as described in section
IV.A.4 of this preamble.
    Instrument monitoring. Instrument monitoring would require you to
check for leaks with a portable instrument in accordance with Method 21
of 40 CFR part 60, appendix A-7. A leak would be detected if you obtain
an instrument reading above the threshold (i.e., leak definition)
specified in the applicable section of the proposed regulation. If you
detect a leak, you would be required to repair the leak as described in
section IV.A.4 of this preamble. The frequency at which you would be
required to conduct instrument monitoring is specified for each type of
equipment. For some equipment, the required monitoring frequency varies
depending on the percentage of the equipment in the applicable process
unit that was determined to be leaking in previous monitoring periods.
In addition to following the procedures in Method 21 of 40 CFR part 60,
appendix A-7, the proposed rule would require you to conduct a
calibration drift assessment at the end of each monitoring day. The
proposed rule also specifies procedures that would allow you to correct
instrument readings for background concentrations of regulated
materials.
    Optical gas imaging. Another method of detecting leaks from
equipment is to scan equipment using a device or system specially
designed to use one of several types of remote sensing techniques,
including optical gas imaging of infrared wavelengths, differential
absorption light detection and ranging [DIAL], and solar occultation
flux. The most common optical gas imaging instrument (also referred to
as a ``camera'') is a passive system that creates an image based on the
absorption of infrared wavelengths. A gas cloud containing certain
hydrocarbons (i.e., leaks) will show up as black or white plumes
(depending on the instrument settings and characteristics of the leak)
on the optical gas imaging instrument screen. This type of optical gas
imaging instrument is the device on which our optical gas imaging
provisions are based.
    On December 22, 2008, we published an Alternative Work Practice
(AWP) for LDAR that includes a combination of optical gas imaging and
instrument monitoring techniques (73 FR 78199). The AWP provisions are
located in the General Provisions in 40 CFR parts 60, 61 and 63, so any
source subject to LDAR requirements in any current equipment leak rule
may elect to comply with this AWP. (This includes the proposed Uniform
Standards, as proposed 40 CFR part 65, subpart H specifies that those
sections would continue to apply to the referencing subparts.) In
addition, we are proposing the optical gas imaging-only provisions
described in section IV.A.5 of this preamble. If specifically allowed
by your referencing subpart, you would be allowed to use optical gas
imaging rather than instrument monitoring to detect leaks from your
equipment. You would be required to comply with the leak survey
procedures for an optical gas imaging device that will be proposed in
40 CFR part 60, appendix K.
    Equipment design. Proposed standards for some equipment consist of
design features that either provide an additional barrier to emissions
or provide for collection of otherwise discharged material for recycle,
reuse or treatment. Where applicable, the specific requirements for
each type of equipment and control level are described in section
IV.A.4 of this preamble.
4. What are the specific equipment leak standards we are proposing?
    As in current equipment leak rules, the proposed Uniform Standards
for equipment leaks are based on a combination of standards, including

LDAR programs, equipment design standards and performance standards. In
addition, we are proposing two alternative means of compliance that can
be used only in specific situations. Many of these proposed equipment
leak standards are consistent with current equipment leak standards.
The discussion in this section IV.A of the preamble describes all
elements of the proposed standards. Section IV.B of this preamble
discusses how we developed the proposed provisions and describes how
the proposed provisions are consistent with one or more previous rules
or why we are introducing additional requirements unique to this
proposal.
    For most types of equipment, current rules specify separate
requirements for equipment in different types of service (e.g., gas and
vapor service, light liquid service). The proposed Uniform Standards
also follow this type of approach; for certain types of equipment
(e.g., valves), the proposed Uniform Standards include specific
instrument monitoring requirements for equipment in gas and vapor
service and equipment in light liquid service and specify specific
sensory monitoring requirements for equipment in heavy liquid service.
We are also proposing that the sensory monitoring requirements would
apply to other equipment that meet certain criteria, such as equipment
in regulated service less than 300 hr/yr and equipment that contains or
contacts regulated material, but not in sufficient quantities to be
operating in regulated material service.
    Section IV.A.4 of this preamble describes proposed standards for
specific types of equipment. After you identify indications of a
potential leak using sensory monitoring or identify a leak using
instrument monitoring, optical gas imaging or other method, the
proposed rule would require you to repair the leaking equipment using
procedures that also are summarized in section IV.A.4 of this preamble.
Finally, alternative equipment leak standards that are provided in the
proposed rule are summarized in section IV.A.4 of this preamble.
    Proposed requirements for valves in gas and vapor service and
valves in light liquid service. We are proposing that for valves in gas
and vapor service and valves in light liquid service, you would be
required to conduct instrument monitoring on a monthly basis for at
least the first 2 months after initial startup. An instrument reading
of 500 parts per million (ppm) or greater would indicate a leak
requiring repair. Following the first 2 months, you would be required
to conduct instrument monitoring at a frequency dependent upon the
percentage of leaking valves within the process unit in those first 2
months (the proposed frequencies range from monthly if more than 2
percent of the valves were leaking to biennially if less than 0.25
percent of the valves were leaking). We are also proposing that you may
use prior monitoring data in lieu of conducting initial monthly
monitoring. For example, if your valves in gas and vapor service and
valves in light liquid service are already subject to instrument
monitoring and repair of leaks at 500 ppm or greater, you would be able
to consider the monitoring data collected under your current rule to
determine your monitoring frequency for the Uniform Standards.
    We are also proposing provisions for subgrouping valves for
monitoring purposes. We are proposing specific monitoring and repair
requirements for valves located at a plant site with fewer than 250
total valves, valves for which the valve mechanism is not connected to
a device that penetrates the valve housing (e.g., most check valves),
unsafe-to-monitor valves and difficult-to-monitor valves.
    Proposed requirements for pumps in light liquid service. We are
proposing monthly instrument monitoring for pumps in light liquid
service. The instrument reading indicating a leak would vary based on
the type of material being handled by that pump: 5,000 ppm or greater
for pumps handling polymerizing monomers and 2,000 ppm or greater for
all other pumps. In addition to instrument monitoring, you would be
required to conduct a weekly visual inspection of all pumps in light
liquid service for dripping liquids. If you found indications of
liquids dripping, you would be required either to repair the pump seal,
eliminating the indications of liquids dripping or to conduct
instrument monitoring. If you elected to conduct instrument monitoring,
the instrument reading that defines a leak requiring repair would be
5,000 ppm for a pump handling polymerizing monomers or 2,000 ppm for
all other pumps.
    We are also proposing specific monitoring and repair requirements
for pumps equipped with a dual mechanical seal system that includes a
barrier fluid system, pumps with no externally actuated shaft
penetrating the pump housing, pumps located within the boundary of an
unmanned plant site, unsafe-to-monitor pumps and difficult-to-monitor
pumps.
    Proposed requirements for connectors in gas and vapor service and
connectors in light liquid service. If your referencing subpart
specifically references proposed 40 CFR 65.422, you would be required
to conduct instrument monitoring for connectors in gas and vapor
service and connectors in light liquid service, and you would be
required to conduct initial instrument monitoring within 12 months of
the compliance date specified in a referencing subpart or 12 months
after initial startup, whichever is later. We are also proposing to
specify that if all the connectors in a process unit have been
monitored for leaks prior to the compliance date specified in the
referencing subpart, no initial monitoring is required, provided that
either no process changes have been made since the prior monitoring or
you can show that the results of the monitoring reliably demonstrate
compliance despite process changes. Following the initial monitoring,
you would be required to conduct instrument monitoring at a frequency
between annually and every 8 years, depending on the percentage of
leaking connectors within the process unit. An instrument reading of
500 ppm or greater would indicate a leak that would require repair. We
are also proposing specific monitoring and repair requirements for
unsafe-to-monitor connectors; difficult-to-monitor connectors; and
inaccessible, ceramic or ceramic-lined connectors. Note that you would
only be required to conduct instrument monitoring for connectors in gas
and vapor service and connectors in light liquid service if your
referencing subpart specifies that you must comply with proposed 40 CFR
65.422.
    Proposed requirements for agitators in gas and vapor service and
agitators in light liquid service. We are proposing monthly instrument
monitoring for agitators in gas and vapor service and agitators in
light liquid service. An instrument reading of 10,000 ppm or greater
would indicate a leak that would require repair. In addition to
instrument monitoring, you would be required to conduct weekly visual
inspection of agitators. If you found indications of liquids dripping
from the agitator seal, you would be required either to repair the
agitator seal, eliminating the indications of liquids dripping or to
conduct instrument monitoring. If you elected to conduct instrument
monitoring, the instrument reading that defines a leak would be 10,000
ppm or greater. We are also proposing specific monitoring and repair
requirements for agitators equipped with a dual mechanical seal system
that includes a barrier fluid system, agitators with no externally
actuated shaft penetrating the

agitator housing, agitators located within the boundary of an unmanned
plant site, agitators obstructed by equipment or piping, unsafe-to-
monitor agitators and difficult-to-monitor agitators.
    Proposed requirements for PRD. Proposed 40 CFR 65.424 includes
operational requirements and pressure release management requirements
for all PRD in regulated material service. We are proposing that you
operate PRD in gas or vapor service with an instrument reading less
than 500 ppm above background. If your PRD includes or consists of a
rupture disk, you would be required to install a replacement disk no
later than 5 calendar days after each pressure release. In addition,
after each pressure release from a PRD in gas or vapor service
(regardless of the type of PRD), you would be required to conduct
instrument monitoring to confirm that the instrument reading is less
than 500 ppm no later than 5 calendar days after the PRD returns to
regulated material service following a pressure release.
    In addition, we are proposing provisions that would apply only if
your referencing subpart specifies that no releases to the atmosphere
are allowed from any PRD in regulated material service. We are
proposing that for each such PRD, you would be required to install and
operate a monitor capable of identifying a pressure release, recording
the time and duration of each pressure release and notifying operators
that a pressure release has occurred. We are also proposing that if the
monitor is capable of monitoring concentration of any flow through the
PRD, then you would not also be required to conduct separate instrument
monitoring no later than 5 calendar days after the PRD returns to
regulated material service following a pressure release to confirm that
the instrument reading is less than 500 ppm. You would also be required
to calculate, record and report the quantity of regulated material
released during each pressure relief event. Note that your referencing
subpart may include other requirements for releases to the atmosphere
as well.
    Proposed requirements for compressors. We are proposing two
compliance options for compressors in regulated material service. The
first would be to equip the compressor with a seal system that includes
a barrier fluid system and that prevents leakage of process fluid to
the atmosphere. You would determine, based on design considerations and
operating experience, a criterion that indicates failure of the seal
system, the barrier fluid system or both. You would also be required to
equip the compressor with a sensor that would detect a failure of the
seal system, the barrier fluid system or both. If a failure is
indicated by either of those methods, a leak is detected, and you would
be required to repair the leak. You would also be required to conduct
sensory monitoring for all potential points of vapor leakage on the
compressor other than the seal system.
    The second option would be to designate that the compressor
operates with an instrument reading of less than 500 ppm above
background at all times. After you initially confirm that the
compressor has an instrument reading less than 500 ppm, you would be
required to conduct ongoing instrument monitoring at least annually to
demonstrate that the compressor operates with an instrument reading of
less than 500 ppm above background. If the instrument reading from any
part of the compressor is 500 ppm above background or greater, the
compressor would not be in compliance with proposed 40 CFR part 65,
subpart J until the next instrument reading of less than 500 ppm above
background.
    Proposed requirements for sampling connection systems. We are
proposing equipment design standards for sampling connection systems.
You would be required to equip the sampling connection system with a
closed-purge, closed-loop or closed vent system. You would be required
to control purged process fluids by returning them to the process line,
to a process, routing them to a control device, routing them to a fuel
gas system or treating them in a waste management unit, a hazardous
waste treatment facility or a device used to burn used oil for energy
recovery (all of which would be required to meet specific standards).
Gases displaced during filling of the sample container and gases
remaining in the tubing or piping between the closed-purge system
valve(s) and sample container valves(s) after the valves are closed and
the sample container is disconnected are not considered to be purged
process fluids and would not be required to be collected or captured.
We are proposing to clarify that analyzer vents are considered sampling
connection systems (and that CEMS are not considered analyzer vents).
In-situ sampling systems and systems without purges would be exempt
from these standards.
    Proposed requirements for open-ended valves and lines in gas and
vapor service and open-ended valves and lines in light liquid service.
We are proposing equipment and operational standards for open-ended
lines and open-ended valves. You would be required to equip open-ended
valves and lines with a cap, blind flange, plug or second valve. The
cap, blind flange, plug or second valve would be required to seal the
open-ended valve or line at all times, except during operations
requiring process fluid flow through the open-ended valve or line,
during maintenance or during operations that require venting the line
between block valves in a double block and bleed system. If the open-
ended valve or line is equipped with a second valve, you would be
required to close the valve on the process fluid end before closing the
second valve.
    In addition, you would be required to conduct annual instrument
monitoring to demonstrate that the open-ended valve or line operates
with an instrument reading of less than 500 ppm above background (i.e.,
that the cap, blind flange, plug or second valve seals the open-ended
valve or line at all times). If the instrument reading is 500 ppm above
background or greater, the open-ended valve or line would not be in
compliance with proposed 40 CFR part 65, subpart J until the next
instrument reading of less than 500 ppm above background.
    Open-ended valves and lines in an emergency shutdown system that
are designed to open automatically in the event of a process upset
would be exempt from the equipment design and instrument monitoring
requirements. However, if your referencing subpart specifies that
releases to the atmosphere from these types of open-ended valves and
lines are not allowed, then any time an open-ended valve or line of
this type does release to the atmosphere, it would not be in compliance
with proposed 40 CFR part 65, subpart J. (Note that your referencing
subpart may include other requirements for releases to the atmosphere
as well.) In addition, open-ended valves and lines containing materials
that would auto catalytically polymerize or would present an explosion,
serious overpressure or other safety hazard if capped or equipped with
a double block and bleed system would be exempt from the equipment and
instrument monitoring requirements. Instead, you would be required to
conduct sensory monitoring for these open-ended valves and lines.
    Proposed requirements for equipment in closed vent systems and fuel
gas systems. We are proposing operational standards for equipment in
closed vent systems and fuel gas systems. You would be required to
conduct annual instrument monitoring to demonstrate that each piece of
equipment in a closed vent system or fuel gas system operates with an
instrument reading of less than 500 ppm above background. If the

instrument reading is 500 ppm above background or greater, the
equipment would not be in compliance with proposed 40 CFR part 65,
subpart J until the next instrument reading of less than 500 ppm above
background.
    Proposed requirements for detecting leaks from other equipment. We
are proposing that sensory monitoring would be the basic level of
control for all equipment. Sensory monitoring would be required for all
equipment that contains or contacts regulated material, but is not
required to comply with the specific requirements in proposed 40 CFR
65.420 through 65.427. This would include: (1) Equipment at a plant
site with less than 1,500 total pieces of equipment; (2) equipment that
contains or contacts regulated material, but not in sufficient
quantities to be operating in regulated material service; (3) equipment
in regulated material service less than 300 hr/yr; (4) valves, pumps,
connectors and agitators in heavy liquid service; (5) connectors not
required by your referencing subpart to comply with 40 CFR 65.422; (6)
instrumentation systems; (7) PRD in liquid service; (8) any equipment
for which sensory monitoring is required specifically by a provision in
proposed 40 CFR 65.420 through 65.427 (e.g., potential points of vapor
leakage on the compressor other than the seal system, open-ended valves
and lines containing materials that would auto catalytically polymerize
or would present an explosion, serious overpressure or other safety
hazard if capped or equipped with a double block and bleed system); and
(9) any other equipment, as specified by your referencing subpart. If
you found indications of a potential leak, you would be required either
to repair the equipment, eliminating the indications of the potential
leak or conduct instrument monitoring to confirm whether there is a
leak within 5 calendar days of detection. If you elected to conduct
instrument monitoring, the instrument reading that defines a leak
requiring repair is specified in proposed Table 1 to subpart J of 40
CFR part 65.
    We are also proposing special requirements for equipment in vacuum
service. You would be required to identify equipment operating in
vacuum service. You would also be required to demonstrate that the
equipment is operating in vacuum service by installing and maintaining
a pressure gauge and alarm system that will alert an operator
immediately and automatically when the equipment is not operating
vacuum service. If the alarm were triggered, you would be required
either to initiate procedures immediately to return the equipment to
vacuum service or to begin to comply with the applicable requirements
of proposed 40 CFR part 65, subpart J (e.g., comply with the instrument
monitoring requirements of proposed 40 CFR 65.420 for valves in gas and
vapor service and valves in light liquid service).
    Proposed repair requirements. We are proposing to specify that when
the standards indicate that you are required to repair a leak, you
would be required to do so as soon as practical, but not later than 15
calendar days after the leak is detected. You would also be required to
make a first attempt at repair no later than 5 calendar days after the
leak is detected. For leaks detected through instrument monitoring or
optical gas imaging, repair would include instrument monitoring or
optical gas imaging within the specified time frame to verify that the
leak was repaired successfully.
    We are also proposing to allow repairs to be delayed in a few