United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 2771 1
EPA-450, 3-36-00-1
September 1986
Air
Vinyl Chloride
Standards:
Responses to
Comments on
January 1985
Proposed Revisions
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EPA-450/3-86-004
Viny] Chloride Standards:
Responses to Comments on
January 1985 Proposed Revision
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
September 1986
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This report has been reviewed by the Emission Standards and Engineering Division of the Office of Air Quality
Planning and Standards, EPA, and approved for publication Mention of trade names or commercial products is
not intended to constitute endorsement or recommendation for use. Copies of this report are available through
the Library Services Office (MD-35), U S Environmental Protection Agency, Research Triangle Park, North
Carolina 27711, or, for a fee, from the National Technical information Services, 5235 Port Royal Road,
Springfield, Virginia 221 61
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VINYL CHLORIDE STA?iC£RD: RESPONSES TO COWENTS
J £, 1" t' £ p Y' iQP^i poppps"
EMISSION STANDARDS AND ENGINEERING DIVISION
U.S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North~Carolina 27711
SEPTEMBER 1986
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TABLE OF CONTENTS
Section ?age
' . '" 5'. •' 'Mj -'/
" 1 ? l ! V * * "• TJ V ^ T ^ !_ A ^ ! C* C "^ C " * : P 3 0 D ^ ^ °' C ^ !
1.2 SIWAPV OF IMPACTS CF PROMULGATEr ACTION
2.C SUMMARY OF PUBLIC CONVENTS AND RESPONSES
2.2 REVISIONS T0 RELIEF VALVE DISCHARGE STANDARD
2.3 REVISIONS TO LEAK DETECTION' AND REPAIR
REQUIREMENTS 2-22
2.4 DEFINITIONS 2-41
2.5 REVISIONS TO OTHER PARTS OF THE STANDARD 2-58
2.6 MISCELLANEOUS 2-65
3.0 PETITION FOR RECONSIDERATION 3-1
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On January 9, 1985, the U. S. Environmental Protection Agency (EPA)
proposed revisions to the national emission standard fcr vinyl chloride 'VO
(50 FR 1182) under authority of Section 11? of the Clean Air Act. The
standard limits atrr;osphev"'c emissions o^ VC frcr: plants p^ccucir^ ethylt^e
dichloride (EDC) by the reaction cf oxygen and hydrogen chloride with ethylene,
plants producing VC by any process, and plants producing one or more polymers
containing any fraction of VC (e.g., polyvinyl chloride (PVC^. The January-9,
1985, Federal Register notice proposed administrative and clarifying revisions
to the VC standard based on a review of the standard.
Public comments were requested on the proposal in the Federal Register
notice. A total of 16 comment letters were received. Commenters included
industry representatives, representatives of industry trade organizations,
State and Federal legislators, one environmental group and one State regulatory
agency. The public comments are summarized in this document along with
responses to the comments. The comments and responses serve as the basis for
changes and clarifications to the revised standard made between proposal and
promulgation.
1.1 SUMMARY OF CHANGES SINCE PROPOSAL
In response to the public comments, one major change and a few minor
changes and clarifications have been made in the proposed revisions to the VC
standard. The major change involves the proposed reformatting of the relief
valve discharge standard. Several comments were received that resulted in
withdrawal of the proposed requirements for relief valve discharges.
Other comments resulted in several minor clarifications to definitions
and other regulatory language.
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The revised definition of "EDC purification" in the proposed
standard has been further darkled by specifically exempting
intermediate and final product storage.
The definition of relief valve has beer modified to exclude two
specific pressure contro1 systems: polymerization shortstec
systems and refrigerated water systems. Also, emissions frcii;
pressure relief devices that control exhaust gas flow to
incinerators are not considered relier valve discharges.
The definition of leak has been clarified by adding the EPA test
method en which leak measurements are to be based, "he orcv'sicn
specifying that leaks are emissions not regulated under exhaust gas
provisions has been dropped.
Three-hour averaging periods have been specified in the -
oxychlorination vent standard and in three other provisions where
exhaust gas limits are prescribed. (Three-hour averages were
specified in all other exhaust gas provisions in the proposed
standard.)
Certain open-ended lines have been made exempt from Subpart V
requirements.
The provision allowing plants to demonstrate effectiveness of
existing leak detection and repair programs through a performance
test of a sample of valves has been revised to more clearly indicate
the number of valves required to be tested.
Method 601 of 40 CFR 136.3 was approved and incorporated by reference
for measurement of VC in inprocess wastewater.
The American Society of Testing and Materials (ASTM) method for
determining by process sample whether equipment is in VC service
has been incorporated by reference.
The definition of connector in Subpart V has been modified to allow
exemption from reporting and recordkeeping requirements for all
screwed and welded connectors and flanged connectors that are
covered by insulation or other materials.
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1.2 SUMMARY OF IMPACTS OF PROMULGATED ACTION
No changes in the environmental, energy and economic impacts of the
standard have occurred since proposal. Further, since no major revisions tc
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2.n SUW^Y OF PUBLIC ccCu^Ts AN: RESPONSES
This document includes responses to public comments on the proposed
revisions to the VC standard. A list of the ccmmenters. their a^'i 1 iations.
and the EPA docket numbers assigned to their correspondence is given in
Tfble 2-1, The ccir,;r.ent3 f.re organized according to fopic in t'^e To1 ~ov ^
sections.
2.1 General Policy and Legal Issues
2.2 Revisions to Relief Valve Discharge Standard
2.3 Revisions to Leak Detection and Repair Requirements
2.4 Definitions
2.5 Revisions to Other Parts of the Standard
2.6 Miscellaneous
2.1 GENERAL POLICY AND LEGAL ISSUES
Comment Level of Standard
Six ccmmenters (IV-D-1, IV-D-2, IV-D-6, IV-D-11, IV-D-12, IV-D-13)
addressed the level of control associated with the VC standard. Three
comment.ers (IV-D-1, IV-D-2, IV-D-6) agreed with the EPA's decision not to
regulate additional sources or change the quantitative emission limits of the
standard. They alleged no basis exists for making the standard more stringent
based on health effects, and that there is no new technology which would
justify a more stringent standard. One commenter (IV-D-6) further stated
that in light o^ the EPA's findings that other regulations have been effective
in reducing VC emissions, a more stringent standard under Section 112 cannot
be justified. In contrast, four other commenters (IV-D-11, IV-D-12, IV-D-13,
IV-D-16) stated that the level of the standard would be weakened by the
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TABLE 2-1. LIST OF COMMENTERS ON PROPOSED REVISIONS
TO THE VINYL CHLORIDE STANDARD
Docket Item Number3 Conmenter and Affiliation
The Vinyl Institute
355 Lexington Avenue
New York, New York. 10017
Date: March 15, 1985
IV-D-2 David L. Lul1
Occidental Chemical Cooperation
P.O. Box 699
Pottstown, Pennsylvania 19464
Pate: March 19, 1985
IV-D-3 J. C. Ledvina
Vista Chemical Company
P.O. Box 19029
Houston, Texas 77224
Date: March 21, 1985
IV-D-4 R. R. Kienle
Shell Oil Company
P.O. Box 4320
Houston, Texas 77210
Date: March 19, 1985
IV-D-5 Paul M. King
PPG Industries, Inc.
One PPG Place
Pittsburgh, Pennsylvania 15272
Date: March 22, 1985
IV-D-6 John T. Barr
Air Products and Chemicals, Inc.
P.O. Box 538
Allentown, Pennsylvania 18105
Date: March 20/1985
IV-D-7 William T. Newman
Georgia Gulf Corporation
P.O. Box 629
Plaquemine, Louisiana 70765-0629
Date: March 20, 1985
aThe docket number for this project is A-S1-21. Dockets are on file at
EPA's Central Docket Section in Washington, D.C.
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TABLE 2-1 (Continued). LIST OF COMMENTERS ON PROPOSED REVISIONS
TO THE VINYL CHLORIDE STANDARD
Dow Chemical U.S.A.
2030 Willard H. n0w Center
'•lid1 and, Micri.can 4564C
Date: Yarch 19, 1985
Chemical Manufacturers
2501 M Street, N.1/.'.
Washington, D.C. 20037
Date: March 25, 1985
IV-D-10 Charles A. Johnson
National Solid Wastes Management
Association
1730 Rhode Island Avenue, N.W.
Washington, D.C. 20036
Date: March ?1, 1985
1V-0-11 Jeffrey G. Mack
Delaware House of Representatives
Dover, Delaware 19904
Date: March 21, 1985
IV-D-12 David D. Doniger
National Resources Defense Council
1350 New York Avenue, N.W.
Washington, D.C. 20005
Date: March 25, 1985
IV-D-13 Tom Carper
U.S. House of Representatives
Washington, D.C. 20515
Date: March 25, 1985
IV-D-14 James D. Fannin
The BF Goodrich Company
6100 Oak Tree Boulevard
Cleveland, Ohio 44131
Date: March 19, 1985
The docket number for this project is A-81-21. Dockets are on file at
EPA's Central Docket Section in Washington, D.C.
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TABLE 2-1 (Concluded). LIST OF COMMENTERS ON PROPOSED REVISIONS
TO THE VINYL CHLORIDE STANDARD
TY-C-15 V:. EaTe'/ Barton
Borclen Inc.
165 M. Washington Avenue
Columbus, Ohio 43215
Date: March 25, 1985
-»' - j - j. G ." a" r" c" a L . . z r ~ o r,
Louisiana Department of
Environmental Quality
P.O. Box 44066
Baton Rouge, Louisiana 70804
Date: April 2, 1985
The docket number for this project is A-81-21. Dockets are on file at
EPA's Central Docket Section in Washington, D.C.
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proposed changes and should be made more stringent. One commenter (IV-D-11)
stated that EPP should replace the standard with one which provides additional
risk reduction. The other commenter (IV-D-13) argued that the level of the
standard should be based on the protection of public health and the environ-
ment, rather than the ability cf i'ldus^ry to comply with the standard, "he
commenter stated the level of the standarc should prov'ce incer.^'.e -"or tne
development of improved emission control systems.
Response
These comments relate to huv; E?a se^cfs the level o~ ccr^ro1 "or
standards under Section 11? of the Clean Air Act. As noted by these
commenters, standards set by EPA under Section 112 reflect the level of
control necessary to provide an ample margin of safety to protect public
health. However, in contrast to some of the ccmmenters, EPA believes that
this level of control must also be achievable to be meaningful and to avoid
being arbitrary and capricious. The VC standard, established in 1976 as an
appropriate level of control under Section 112, represented the most stringent
level of control that can be achieved by VC and PVC plants based on best
available technologies, while avoiding unreasonable cost. Because the
revisions to the standard proposed on January 9, 1985, did not substantively
change the level of control associated with the standard, EPA considered
these comments in the context of the level of control established in 1976.
As discussed in more detail in the follov/ing response, EPA concluded that the
level of control in the VC standard is appropriate.
Comment Zero Discharge Goal and Consideration of Costs
Two commenters (IV-D-1, IV-D-6) concurred with the EPA's conclusion that
Section 11? of the Clean Air Act does not require emissions of VC to be
eliminated. One of the commenters (IV-D-1) added that the 1977 proposed
amendments were based on the "erroneous premise" that a zero discharge level
should be achieved. In contrast, another commenter (IV-D-12) pointed out
that EPA previously recognized a zero emissions goal.
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Three commenters (IV-D-6, IV-D-8, IV-D-12) addressed the use of costs
and cost effectiveness in the development of the standard. Ore commenter
(IV-D-6) emphasized the importance of a sound, cost-effective regulation.
The second commenter (TV-D-8^ stated that the proposed modifications to the
standard ere aimed at reducing emissions in the most cost-effecti"e n.?.rn-?r.
even though some new requirements have been adaed. Ccn-'ersely, two commer'Ters
(IV-D-11, IV-D-12) objected to the EPA's consideration of costs in developing
the VC standard.
Response
In the EPA's judgment, the VC standard protects the public health within
the meaning of Section 112, and EPA may consider cost and feasibility in
setting the standard. The EPA views are explained in the 1975-76 VC rule-
making, and in the Agency's brief in NRDC v. hPA, No. 85-1150 (D.C. Cir).
The NRDC/EDF provided no new information on this issue.
Comment Emission Standards vs. Equipment and Work
Practice Standards
The commenter (IV-D-16) stated that uncertainties in the existing
standard have required enforcement personnel to develop enforcement policies
outlining the level of effort expected of plants for compliance. The commenter
recommended that revisions to the standard specify required equipment and
operating practices for meeting the existing limits. Revising the standard
in this manner would ensure continued strict control of VC emissions while
providing industry and enforcement personnel with specific guidance on
required level of effort. The result would be more effective enforcement of
the standard.
Response
Under the requirements of the Clean Air Act, as amended, EPA is to set
emission (i.e., performance) limits wherever possible and to allow the owners
and operators of affected facilities to achieve that limit in any way
available. In the case of VC emissions, it is both possible and appropriate
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to establish an emission limit for most sources. Thus, EPA can not require
the use of specific types of equipment for most of the sources covered by the
standard. However, where it is not practicable to set an emission standard,
E0A has required the use or equipment and other work practices.
Comment
One commenter (IV-D-1) questioned the need for a standard regulating VC
emissions on the basis of heaHh r-'sks, citing fhe absence of h'jnan deaths
related to VC exposure in the vicinity of regulated plants. Another commenter
exposure are proof of the success of the VC standard.
Response
Generally, the absence of specific evidence linking human deaths related
to VC emissions to the environment is not indicative of the absence of risk
from these emissions. At the time the original VC standard was developed,
unit risk factors were developed based on studies of the health effects from
exposure to VC emissions. These health studies implicated instances of liver
angiosarcoma, other cancers, and noncarcinogenic disorders in animals from
inhalation of VC. While there have been no recent epidemiological studies
relating to exposure to VC emissions, instances of liver angiosarcoma in
individuals exposed to VC have been reported. As part of the review of the
VC standard, the EPA carcinogen assessment group reviewed the original health
studies and subsequent health information which confirmed the link between VC
exposure and brain and liver cancer. The review concluded that the health
effects associated with VC and the risk estimates developed at the time of
the original standard remain valid.
To the extent that the original VC standard has been effective in
reducing or eliminating incidences of cancer due to exposure to VC, then the
efforts of EPA, industry and individuals in controlling VC emissions have
been successful. However, given the latency period for health effects and
the existence of confounding variables in exposure and development of cancer,
both the Agency and industry should continue to make reasonable efforts to
continue controllina VC emissions.
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Comment Technology Demonstration Requirements
One ccrcmenter (IV-D-12) stated that there is no language in Section 112
which would require a control technology or emission level to be demonstrated
in order to serve as the basis of a NESHAP. The cornmenter pointed to the
control which has been consistently achieved1' as indicative thac i?A was
applying such a requirement in evaluating alternative exhaust gas limns.
The corr.menter stated that the Requirements of Section 112 are intended to be
technology forcing, based on projections of the capabilities of technology
rathe*" tnan or oast 5c.nJ"i.'efr'oT;"^
Response
The VC standard was established at a level which was determined to be
achievable using best available control technologies. The data on VC emissions
control indicate that a 5 ppm emission limit would not be consistently
achievable, and EPA selected a 10 ppm emission limit to reflect the level of
control required by the standard. In doing so, EPA considered both the
feasibility of this level of control and the health impacts resulting from
this control level including that the standard provides an ample margin of
safety for public health.
Comment Withdrawal of 1977 Proposal
Three commenters (IV-D-4, IV-D-7, IV-D-14) stated their support for the
EPA's withdrawal of the 1977 proposed amendments to the standard.
Response
As discussed in the preamble (50 FR 1183), EPA did not believe it was
appropriate to leave the proposed amendments to the VC standard in effect or
to promulgate amendments based on the proposed amendments. This decision was
the outcome of a review procedure that considered the 1977 proposal, as well
as a recent revaluation of existing and new control technologies, of VC
sources not regulated by the standard and of enforcement and compliance
experience since promulgation of the standard.
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Comment Effectiveness of VC Standard
One ccmmenter {IV-D-14) stated that the industry has effective"1 y
implemented the VC standard as evidenced by the fact that actual VC emission
reductions unde^ the standard have exceeded the oncina"! standard estimates.
Ar,othe-~ C3:r~e:it,;r ''V-D-lf' a" so staged "hat the v'C staricard l-.;^ '~ee"
success^ii" ir greatly reducing VC eri-'ssions, arc pointer oL.t t;i~ ccnsic^'^c" -
expense to plants in Louisiana to install control equipment and implement
operative procedures to nee4: the standard.
No response necessary.
Comment Clarification of Preamble and Peculation
Three commenters (IV-D-i, IV-D-6, IV-D-9) stated that the explanation c~
the standard contained in the preamble and the language of the standard
itself need to be clarified and made more consistent. One commenter (IV-D-1^
suggested that the interpretative language of the preamble be incorporated
into the standard, where appropriate, to help ensure consistent interpretation,
The commenter stressed the importance of resolving uncertainties associated
with the standard to prevent unnecessary cost to the industry and EPA. A
second commenter (IV-D-6) also emphasized the need to remove all ambiguity
from the standard to prevent the costs of negotiation and litigation caused
by differing interpretations of the standard.
Response
One purpose of the proposed revisions was to enhance the clarity of the
requirements of the VC standard. All specific instances of confusion over
provisions of the standard and the language of the preamble cited by the
commenters have been addressed in other responses directed toward the relief
valve definition, the leak detection requirements, the applicability of the
standard to storage tanks, the three-hour averaging period, and other issues.
The EPA believes that with these clarifications the requirements of the
standard are clear and consistent with the intent of this action.
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Comment Need to Update Standard
The commenter (1V-D-14) emphasized the need to update the standard based
on eight years of experience by EPA and industry since promulgation of the
standard. He noted that EPA has effectively analyzed experience under the
standard in developing rev's ions.
Response
No response necessary.
CcTrent Authority for Work Practice Stanr'ards
The commenter (IV-D-1) restated industry's position during the original
rulemaking that EPA had no legal authority at that time to promulgate work
practice rules.
Response
What the Agency's authority was in 1976 is not a subject of this
rulemaking.
2.2 REVISIONS TO RELIEF VALVE DISCHARGE STANDARD
2.2.1 Numerical Limit Format
Comment Numerical Limit Format
Seven commenters (IV-D-2, IV-D-7, IV-D-9, IV-D-12, IV-D-13, IV-D-14,
IV-D-16) addressed the numerical limit format selected for the relief valve
discharge standard.
Four commenters (IV-D-11, IV-D-12, IV-D-13, IV-D-16) objected to the
proposal to grant an allowable relief valve discharge rate. One of these
commenters (IV-D-16) stated that although the proposed revised relief valve
discharge requirements more clearly specify which relief valve discharges are
in violation of the standard, they do not penalize discharges which may be
caused by gross negligence. The second commenter (IV-D-12) urged EPA to
retain the existing standard that relief valve discharges are violations of
the standard unless unpreventable. The commenter stated that EPA has presented
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no analysis of the "significant" burden on Agency resources which was cited
as one reason for the proposal. Further, the commenter stated that preventable
discharges should be avoided as a matter of principle, and pointed out that
've discharges are the single largest remaining source
emissions
at s orris nlan+'s. Final!1'/ '""h^ ^GiTir^^r^ei' ^b'f^c^cd ~~< ^h-^ --~1^v?'" "- ^ '" ~~'r':\r~~-
provision as being a significant weakening of the standard s~;nce cvrvent £3-
enforcement policy has routinely concluded that the vast majority of releases
are preventable. The ccrrneiter expressed concern that the rubefies"! 1in;"i?
would legitimize the current discharge rates by industry, regardless of the
p s 1 1 -i ••- i ' -t- n » pu'0 v> •*- -- on"< •«- M jo "t" P c; ^ '^o -t- n T y-* n r- rM~irr 0 ri •?• d v- • 7' __ r ,. ~ < c *~ ,-, "_;'•' ~ i' ^ - - "> L.
proposed numerical standards are not consistent with the Congressional inte-t
for the regulation of hazardous substances. The commenter pointed out that
the proposed standards would be less stringent than the retirements of a
consent agreement reached in a recent case against Formosa Plastics in
Delaware. The commenter stated that the recent relief valve discharge
performance of the Formosa Plastics facility would not have been affected by
the proposed standard, even though it was the top VC emitter in the country.
Both commenters IV-D-11 and IV-D-12 urged EPA to drop the proposed revisions
and to develop more stringent requirements for relief valve discharges.
Four commenters (IV-D-2, IV-D-7, IV-D-9, IV-D-14) expressed general
support for the EPA's proposal of numerical limits. One of these commenters
(IV-D-14) stated his belief that the proposed numerical limits for relief
valve discharges are practical but sufficiently stringent to require further
progress by industry in preventing discharges. Another of these commenters
(IV-D-2) further urged EPA to adopt an enforcement policy of reviewing al i
relief valve discharge incidents in excess of the limits and suspending
enforcement if those incidents were deemed to be emergencies.
Response
At the time the original VC standard was developed, it was recognized
that relief valves and other safety relief devices are a potential source of
VC emissions which are controllable through a combination of equipment and
work practices. However, information was not available on the effectiveness
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of control measures on relief valve discharge performance. The original
standard regulated relief valve discharge emissions by prohibiting all
nonemergency discharges. Emergency discharges are described as those which
could not have been, avoided by taking measures to prevent the discharce.
This standard is ar eir,~'ss":cn cr performance standard t~at liT."i~3 ;"" ".
emissions except those resulting from emergency discharges.
During the review of the VC standard begun in 1980 and completed in
1982, including enforcement and compliance experience under the VC stand?rd.
EPA enforcement personnel reported significant manpower and resource require-
ments we"^6 bf3 i nc usPd r ° p,;^n i ^"o r rnTn"* ^ ~* Pr ? i>/n'"" h ^^° r-*^ ~ p"~ * ^ "> \* ^ ~ ~> ^ ~* ^~ ,--~^
standard. Ihis was primarily cue to the effort required tc individually
evaluate each relief valve discharge for preventability. The review study
a"!so found that many producers were uncertain about whether they complied
with the relief valve discharge standard. The review study concluded that
the format of the standard should be reviewed, primarily to reduce the
enforcement burden on EPA and to improve industry's understanding of com-
pliance requirements. Based on the recommendations of the review study, EPA
set out to establish a standard for relief valve discharges based on numerical
discharge limits reflecting performance representative of compliance with the
original standard. The results of this effort to reformat the relief valve
discharge standard were proposed in January 1985 (see 50 FR 1182).
In response to comments objecting to the proposed revised relief valve
discharge requirements, EPA has reconsidered the proposed action to add new
numerical limits for relief valve discharges. In particular, EPA has reviewed
the basis for the review study recommendations that the format of the standard
be changed (i.e., to reduce enforcement burden and to improve understanding
of compliance requirements). During the five years since the review study
was conducted, efficiency of activities relating to the enforcement of relief
valve discharge standard has improved. This is due in large part to experience
established over the last 5 years in enforcing the original standard. As a
result, EPA enforcement personnel consider this standard to be much less
resource and manpower intensive. Furthermore, enforcement actions taken by
EPA against a number of plants since the time of the review study have served
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two purposes. First, they have resulted in improved control of relief valve
discharges accompanied by a reduction in relief valve discharge emissions.
Second, some of these enforcement actions have resulted in consent decrees
which outline specific measures required to be taken by the individual plant
for ccmo'iiance purposes. Trese consent decrees net only serve to clari~y
compliance reauirerr.ents for tne subject p^r.' but serve as guidelines fc-~ aP
plants of the types of measures deemed appropriate by EPA for controlling
relief val'pe discharges. In this way, understanding of compliance requirements
has been appreciably improved. Because these recent findings tend ^o invali-
date ~he major conclusions of the review study, EPA believes it is r? longer
appropriate to reformat the original standard. Consequently, the proposed
numerical limits for relief valve discharges are not being promulgated.
2.2.2 Level of Numerical Limits
Comment Cap on Mass Emissions, 100-Pound
De Minimus Exemption
The commenter (IV-D-13) stated that the revised relief valve discharge
limits should also include a cap on the size of discharges so that the
quantity of VC emitted is regulated in addition to the frequency of discharge
events.
Two commenters (IV-D-2, IV-D-7) recommended that relief valve discharges
less than 100 pounds be exempted from the revised relief valve discharge
requirements. One of the commenters (IV-D-7) emphasized the small environ-
mental impact of brief relief valve "chatter" incidents. The second commenter
(IV-D-2) stated that the administrative burden and personnel requirements for
investigating, documenting, reporting, and negotiating minor discharges are
disproportionate to the corresponding hazard to human health.
Response
As discussed in Section 2.2.1, EPA has decided not to reformat the
original standard with numerical limits. The original relief valve discharge
standard provides for review of all discharges, including both large and
small discharges. Any relief valve discharge which is preventable is in
violation of the standard and subject to enforcement.
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Comment Numerical Limit Applied to EDC/VC Production Units
Three commenters (IV-D-1, IV-D-5, IV-D-14) provided recommendations on
applying the relief valve discharge limit for EDC/VC plants to multi-unit
complexes and expanded plants. Commenter IV-D-1 requested that the limit of
4 discharges oer year be applied tc each individual production uMt within a
plant. Commenter IV-D-5 suggested that the limit be applied separately to
each discrete plant under separate management in a multi-plant complex.
Commenter IV-D-1 anso recommended that the relief valve discharge limit be
applied to each new EDC/VC production unit added to an existing facility.
Alternatively, Commenter IV-D-1 agreed w>fb the suggestion o^ another commenter
(IV-D-14) that the limit for expanded EDC/VC plants be increased in proportion
to the increase in production capacity.
Response
As discussed in Section 2.2.1, EPA has decided not to revise the relief
valve discharge reauirements by adding numerical limits. As done currently,
EPA will continue to evaluate the preventability of each discharge.
2.2.3 Control Measures
Comment Equipment Requirements in Relief Valve
Discharge Standard
The Commenter (IV-D-16) requested that the revised standard delineate
the types of measures considered adequate to prevent unnecessary discharges
from relief valves and failed equipment. In particular, the commenter
(IV-D-16) recommended that a provision be added to the standard requiring a
level of redundancy for any equipment and control instrumentation which
influence operating pressures so that failure of a single equipment piece or
control instrument does not cause a relief valve discharge from
overpressurization.
Response
I he approach recommended by the commenter is inappropriate in this case.
The Clean Air Act, as amended, requires EPA to establish emission standards
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(i.e., performance standards) unless they are not feasible to prescribe or
enforce. Thus, because EPA can establish an emission/performance standard,
such as a standard prohibiting all relief valve discharges except emergencies,
EPA is reouired to do so. Information on the effectiveness of various
equipment arc oseraf'onc." prccecures "or :c"trc"1 ing rslie*" va^'e d•';.';; i-'ces
v;as not available at the time the original star.c'ard was written, "t v/hh,
expected that different combinations of control measures would be equally
effective in preventing relief valve discu?i/-ges _ pne finding o^ the revie^
study was that individua1 "contro1 techniques" 'including equipment and
can net be directly related to emissions reduction. Furthermore, the att^.'jce
of plant owners and operators appears to be an important factor in controlling
relief valve discharge occurrences. During visits to five PVC plants with
good performance records, EPA learned that these plants had effectively
implemented different combinations of equipment and work practices for
preventing relief valve discharges fDocket Item II-B-31). Based on these
findings, EPA continues to believe that it is more effective to allow plants
to develop their own combination of preventive measures that will enable them
to eliminate preventable discharges limits rather than to prescribe control
measures.
The EPA agrees that redundant instrumentation and certain other equipment
are an important factor in prevention of relief valve discharges at some
plants. However, the level of redundancy vanes according to plant and the
type of discharge tc be controlled and cannot be uniformly specified for all
plants. Generally, at least one level of redundancy for key instrumentation
and equipment affecting relief valve discharge incidence is considered by EPA
to be necessary for proper operation and maintenance.
Comment Gasholder Containment System
Two commenters (IV-D-11, IV-D-12) urged EPA to strengthen the standard
by specifying the use of all available equipment and practices to minimize
emissions, particularly gasholders. One of the commenters (IV-D-12) stated
that gasholder containment systems are feasible and should not be rejected on
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the basis of cost or the small quantity of emissions that would be controlled
through a gasholder system. The commenter asserted that, cost is an inappro-
priate factor for consideration under Section 112 and that gasholder
containment systems have beer, installed pursuant to enforcement actons.
Further, the commenter ctated ^'r:£t VC enissiors c;ntrcl t^cugh tue L^?. c~
gasholder containment systems should be pursued, even if they are only
effective in controlling emergency releases of VC.
The second commenter (IV-C-11N stated that EPA should examine the L:SS c^
gasholder containment systems en PVC plants to contain releases of VC. This
c cmm^r11 f^r oc" M L 3 c ou~ u n £, ^ ^'! r ^ ? ^ ' '5 ~ ~rr, is DQ ~" n ° ^^ cu i *~>Gd ~*~ ~ r ^ ^ '* C c ' 'J ^ ~ ~f^
Delaware pursuant to a consent decree.
Response
Gasholders are one of many control measures that are available to plants
to control relief valve discharge emissions. In fact, some plants currently
have gasholders available as part of the VC recovery system or as a surge
vessel feeding the incinerator or other primary control device (Docket Item
II-A-19). At least one PVC plant vents relief valves on certain equipment
(i.e., equipment other than reactors and storage spheres) to a gasholder
(Docket Item II-B-31). The EPA is unaware of any plant that currently vents
relief valves on PVC reactors directly to a gasholder.
Although gasholders may be appropriate technology for certain plants to
reduce relie* valve discharge emissions, they are not essential control
technology for all plants, as evidenced by the fact that some plants with the
lowest relief valve discharge rates do not have gasholders. Consequently,
EPA believes it is inappropriate to require gasholders for all plants.
However, EPA does not discourage the use of gasholder containment systems as
a control technology for relief valve discharges when appropriate.
2.2.4 Applicability of Numerical Limits
Comment Multiple Discharges During Single
Overpressure Event
Three commenters (IV-D-1, IV-D-3, IV-D-6) requested that multiple relief
valve discharges that occur from the same piece of equipment because of a
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single overpressure event be considered a single discharge regardless of
whether they occur simultaneously.
Response
This comment refers to the method for counting discharges under the
proposed revised requirements for relief valve discharges which EPA has
decided not to promulgate (see Section 2.2.1). The number of relief valves
"-hat discharge during an overpressure event is ret critical to compliance
determinations under the current standard.
Comment Discharges Vented to a Control Device
I wo ccmmenters (1V-D-1, JV-D-14) requested additional clarification on
the applicability of the relief valve discharge limits to discharges that are
vented to a control device. One commenter (IV-D-1) suggested the limits
specify that only discharges direct to the atmosphere are to be considered
when determining compliance with the limits. The second commenter (IV-D-14)
questioned whether a relief valve discharge vented to a control device not
meeting the 10 ppm limit would be counted as a relief valve discharge for
compliance purposes. He expressed concern that both a 10 ppm violation and a
relief valve discharge violation could be cited if the standard does not
clearly indicate that relief valve discharges conveyed to a control device
are no longer considered to be relief valve discharges regardless of whether
10 ppm is achieved.
Response
As with the previous comment, this comment refers to the method of
determining which relief valve discharges are subject to the numerical
discharge limits. Although EPA has decided not to revise the relief valve
discharge standard (see Section 2.2.1), the discussion on which discharges
are subject to the standard remains valid. Specifying that only relief valve
discharges direct to the atmosphere are to be considered relief valve dis-
charges for compliance purposes is inconsistent with the LPA's intent.
Relief valves that discharge to headers that ultimately discharge to the
-------
atmosphere without control are clearly intended by EPA to be relief valve
discharges subject to the standard.
As explained in the preamble to the proposed revisions (50 FR 1189),
relief valve discharges that are vented to a control device meeting 10 ppm
are exempt from the relief valve discharge standard. Analyses -'nciicate 'cha"
a 99.9 percent reduction in VC content is achievable when a relief valve
discharge is vented through a control device designed to reduce emissions to
10 ppm. Consequently, although it is not feasible to vent, all relief valve
discharges to a control device, benefits in emission reductions are attainable
in many cases. Therefore, the EFA supports and encourages the ventirg of
relief valve discharges to a control device as long as such venting does not
interfere with the ability of the control device to reduce exhaust gas
emissions to 10 ppm. In the event that a relief valve discharge is vented to
a control device while it is not meeting 10 ppm, both the standards for
exhaust gas and relief valve discharges are applicable.
2.2.5 Compliance Method
Comment Batch Production Rate at Bulk Plants
Two commenters (IV-D-1, IV-D-2) requested that the relief valve discharge
compliance method for bulk PYC plants be changed to allow separate counting
of prepolymerization and postpolymerization batches.
Response
This comment is not relevant because it refers to counting of batches
for demonstrating compliance with proposed limits on the number of discharges
per 100 batches. As discussed in Section 2.2.1, EPA has decided not to
revise the relief valve discharge standard.
Comment Effect of Batch Production Rates
One commenter (IV-D-1) stated that the method for determining compliance
with the relief valve discharge limits for PVC plants unduly penalizes plants
whose batch production rates are slightly less than the exact number of
batches needed to qualify for the next integer of permitted discharges. The
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commenter alleged that the method is unfair because business conditions alone
determine how many batches a plant, makes. A second commenter T/-D-15} also
pointed cut the penalty to plants operating at low capacity Hess than 2,85S
batches per yeaH such that a single discharge would violate t^e l^'trit.
Pespcrse
As with the previous comment, this comment is not relevant because EF'a
is no longer planning to reasure compliance with the reln'ef val^e discharge
standard at PVC plants based en a number of allowable discharges per batch
Comment Rounding of Calculated Discharge Frequency
One commenter (IV-D-2) objected to the "preciseness" of the proposed
relief valve discharge limits and requested clarification on how rounding
would be used to compare calculated discharge frequencies to the limits.
Response
As with previous comments, this comment is no longer relevant.
Comment Low Batch Rate Provision
Three commenters (IV-D-1, IV-D-9, IV-D-14) recommended alternative
language for the proposed provision in 40 CFR 61.65(a)(l)(iii) pertaining to
allowable discharges at low batch production PVC plants.
Response
As with previous comments, this comment is no longer relevant.
Comment 2-Year vs. IP-Month Compliance Period
Three commenters (IV-D-1, IV-D-2, IV-D-6), pointed out that the relief
valve discharge limits are based on two years of performance data but are
applied on an annual basis. Accordingly, two of the commenters (IV-D-2,
IV-D-6) stated that a 2-year compliance period would be more appropriate.
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Response
As with previous comments, this comment is no longer relevant.
Comment Fixed 12-Month Compliance Period
Tv>c commen-ers fIV-D-3, IV-D-9) reccrrended that ire ccmp"-'c^cs zer-
for relief valve discharges be chanced from a 12-mcni'n period rolling evs
6 months to a fixed 12-month period to ensure that the same discharge or
group of discharges are net counted towards more than one exccedence.
As with previous comments, this comment is no longer relevant,
Comment Alternative Regulation Format
The commenter (IV-D-2) suggested that the basis of prescribing the
relief valve discharge limits for PVC plants be revised by adopting "a system
of permitted discharges, expressed as whole integers, for increasing incre-
ments of ranges of number of batches polymerized: 2,858 to 5,716; 5,716 to
8,754; etc."
Response
As with previous comments, this comment is no longer relevant.
2.2.6 Reporting Requirements
Comment 10-Day vs. Quarterly Report
Three commenters (IV-D-12, IV-D-13, IV-D-16) objected to the chance in
relief valve discharge reporting requirements from 10-day to quarterly
reporting. Two of the commenters (IV-D-12, IV-D-13) stated that a shorter
reporting period would alert State, Federal and local officials as well as
the public of VC releases sooner. Commenter IV-D-12 urged adoption of a
24-hour reporting requirement as consistent with requirements of the
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).
The third commenter (IV-D-16) explained that the current practice for enforce-
ment personnel to complete investigations of discharges within 45 days of the
incident has been mutually advantageous to industry and enforcement personnel.
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Response
The EPA has reviewed enforcement data and agrees with the cornmenters
that retention of the 10-day reporting requirement is desirable. Federal,
State and local officials promptly review these reports and use the irformation
contained therein in enforcement activity to aid in the preventicr, c* repeal
incidents. Allowing a longer reporting period would net only make it more
difficult to investigate a release because of the passage of time, but would
unnecessarily delay appropriate action by the enforcement agency and possibly
also the source. Further, 1C days is a sufficient time for sources to gather
the needed information to prepare a report.
A 24-hour reporting requirement was not selected. The EPA believes that
the benefits of the 10-day reports would not be significantly increased by
24-hour reporting. Also, at least one State already requires its source to
report discharges by telephone within three hours. The EPA feels that other
States may also include the requirement if the need and enforcement resources
exist. Owners and operators should review and consider the need to report
emissions of VC as they relate to the Comprehensive Environmental Response,
Compensation and Liability Act (CERCLA). In particular, emissions of VC not
allowed by the VC standard and greater than the CERCLA "reportable quantity"
may need to be reported to the National Response Center.
2.3 REVISIONS TO LEAK DETECTION AND REPAIR REQUIREMENTS
2.3.1 Meed for Subpart V in VC Standard
Comment Reouest to Drop Subpart V
Several commenters urged dropping the addition of Subpart V in the VC
standard.
Five commenters (IV-D-4, IV-D-3, IV-D-5, IV-D-14, IV-D-15) stated that
existing leak detection and elimination programs are at least as effective as
Subpart V in controlling equipment leaks. According to these commenters,
applying Subpart V to the VC industry is not justified because emission
reduction would be insignificant and no health benefit would result. Further-
more, Subpart V would create additional administrative burden that would
necessitate an increase in resource and manpower requirements.
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Two commenters (IV-D-3, IV-D-12) stated that incorporation of Subpart V
in the VC standard could potentially result in less stringent control of
equipment leaks because some plants have existing leak detection and elimi-
nation programs with more stringent leak definitions than Subpart V. Comrcenter
IV-D-l? urged EPA to prepare and make public a pcint-by-point analyses
comparing existing leak detection anc elimination programs to requirements in
Subpart V.
Response
The original VC standard required implementation of a -formalized program
for detection of leaks from equipment in VC service and elimination of these
leaks. This program was based on an area-wide monitoring system and routine
use of a portable monitor to detect leaks. Detailed requirements for these
leak detection and repair programs were not specified; rather, plants were
required to develop their own plans subject to approval. During the review
of the original standard, EPA found that existing leak detection and repair
programs implemented by plants vary significantly from plant to plant (Docket
Item II-A-19). While some of the differences in these programs resulted from
site-specific differences in plants (e.g., layout of plant, background
concentration, etc.), others resulted from ineffective approaches to routine
leak detection and repair. For example, differences in plant programs
include variations in leak definitions and monitoring practices. Leak
definitions used in conjunction with portable monitors are very stringent (10
to 25 ppm) at some plants, while some plants have no specific leak level
defined for portable monitors. Some leak definition concentration levels
were comparable to the 10,000 ppm used in the routine program of Subpart V
but were based on measuring the leak at a distance from the equipment rather
than at the surface (leak interface) of the equipment as required by Subpart V.
Similarly, some plants routinely monitor equipment components for leaks with
a portable monitor on a formal schedule, while others monitor for leaks only
when indicated by an area monitor detection. These differences can signifi-
cantly affect the effectiveness of leak detection and repair programs. Based
on these findings, EPA concluded that more specific leak detection and repair
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requirements should be established for certain equipment in VC service. The
EPA did not propose to charge the level of control (emission or risk reductions
or cost implications) with this part of the VC standard as some commenters
indicated, but instead proposed to provide a better way to evaluate compliance
with the original cecisicr. to 'require effective 1e?'\ detection a^c1 e"'""'"at";:;.
As noted in the preamble to the proposed re^'s^ons '50 PR 119C', stuc-'e;
conducted by EPA and industry in conjunction with development of equipment
leak standards for other industries have provided informatics en what ccr.st"'-
tutes an effective program for detecting and repairing equipment leaks since
the VC standaro was f"rc''" veve^op'Sc i n 1975 and 197G. Bas-^c en t^ese 5".' ~"'e;
EPA selected equipment and work practice requirements that represent an
effective leak detection and repair program and included them in 40 CFR Part
61 Subpart V. This subpart, promulgated o-n June 6, 1984, established leak
detection and repair requirements for equipment in volatile hazardous air
pollutant (VHAP) service. These requirements were specifically developed to
regulate emissions of hazardous pollutants such as benzene and are equally
applicable to VC. Accordingly, EPA proposed to designate VC as a VHAP in the
context of Subpart V. Addition of Subpart V to the VC standard would ensure
effective control of equipment leaks on a consistent basis throughout the VC
and PVC industries. (It should be noted that new, modified, or reconstructed
VC production and recovery plants are covered by the new source performance
standard for the organic chemical industry. This standard for VOC emission
is essentially identical to Subpart V.) The basis for adding Subpart V to
the VC standard was explained in detail in the preamble to the proposed
revisions (50 FR 1190-92).
Prior to the January 9, 1985, proposal, EPA requested and then responded
to industry comments by adjusting how Subpart V is to be applied under the VC
standard. At that time, industry comments emphasized the effectiveness of
existing leak detection and repair programs resulting from compliance with
requirements of the VC standard and OSHA. regulations. The industry commenters
suggested that Subpart V be required only for those plants with inferior
programs. While Subpart V already provides alternative standards for reducing
the burden on plants with effective leak detection and repair programs (see
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40 CFR 61.243), industry representatives pointed out that even the alterna-
tive Subpart V requirements would require plants to inventory equipment
components in VC service, an unreasonable administrative burden according to
the industry commerters. Even though EPA ^'rds it difficult to understand
responded to the industry concerns in the January 9, 19S5, prccosal r\v
allowing plant owners and operators to determine compliance with the alterna
tive standards in Subpart V by testing a prescribed sarr.pl e cf a"!"! valves,
thereby reducing significantly the administrative burden associated
with
The EPA disagrees with the comment that Subpart V could result in less
stringent control of equipment leaks than existing programs. In general,
Subpart V represents a better way to determine compliance with requirements
for leak detection and repair. In contrast to the provisions for leak
detection and repair programs in the original VC standard, Subpart V contains
a detailed list of requirements that, once implemented, will result ir
effective control of equipment leaks at reasonable cost. Any plants with
effective existing programs based on more stringent leak definitions or
monitoring practices than Subpart V will continue to effectively control
equipment leaks either by implementing Subpart V or continuing with their
existing program. Any increase in eauipment leak emissions caused by plants
switching to Subpart V would be more than offset by additional reductions
achieved at plants with programs less effective than Subpart V. In this way,
the overall level of control of equipment leak emissions would not be changed
by incorporation of Subpart V in the VC standard.
2.3.2 Applicability of Subpart V Under VC Standard
Comment Option to Implement Subpart V
Two commenters (IV-D-2, IV-D-14) recommended that the regulation clearly
specify that plants may elect to implement Subpart V or continue their
existing leak detection and elimination program supplemented to demonstrate
that less than 2 percent of valves in VC service are leaking. Similarly,
another commenter (IV-D-6) requested that the regulation clearly indicate
>-24
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that plants demonstrating that less than 2 percent of valves are leaking are
not subject to Subpart V. A third commenter (IV-D-14) also recommended that
plants be given the option of continuing existing programs or complying with
Subpart V, explaining that such an option is appropriate in the absence nf
justification that Subpart V is more effective than existing programs.
Response
The EPA will use Subpart V, as reeded, to supplement determination? cf
compliance with the requirements of §61.65(b). Because Subpart V does not
address some sources covered under 55I.65(b1, Si-bpart F will serve as t^e
main basis for determinations of compliance for these sources. For example,
Subpart V does not address loading or unloading lines (except to the extent
such lines are open-ended lines or valves) and, therefore, the requirements
of §61.65(b)(l) will be used to evaluate compliance. Other sources covered
by §61.65(b) (e.g., pumps) are also covered by Subpart V. For these sources,
Subpart V will be used to supplement Subpart F when EPA makes compliance
determinations. The EPA decided to propose and promulgate this approach
because, while the work practices and equipment requirements of Subpart F
specify the goal of the original standard, it did not always clearly specify
how to achieve acceptable compliance. For example, the requirements for
pumps [§61.65(a)(3)(i)] require double mechanical seals or equivalent.
Subpart V goes on to define compliance for all the known equivalent systems
for pumps: other dual seal systems and leakless pumps. The only aspect of
Subpart F where compliance determinations would be substantially changed
concerns the routine leak detection and repair requirements of
§61.65(a)(8)(ii). The basis for this decision is discussed in the previous
response and is needed to spell out clearly how compliance is determined. In
making this change EPA considered options, as requested by industry commenters,
before the standard was proposed and selected an approach as discussed below.
The option recommended by the commenter of continuing the existing leak
detection and elimination program or complying with the Subpart V monitoring
and repair requirements for valves is already offered in the revised standard,
but only for plants who initially, annually, and at the request of EPA
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demonstrate that less than 2 percent of the prescribed sample of valves are
leaking. Plants failing the performance test at any time may no longer e^ect
the option of only continuing their existing program and performing an annual
test. Removal of this option is not unreasonable because failure of the
performance test is indicative that improvement, in ""eak detection and rer?.:t
techniques is needed and warranted. Such improvement is provider! by the
requirements of Subpart V. However, plants required to comply with all
requirements o^ Subpart V may be able to perform annual leak checks instead
of more frequent monitoring. This is possible because Subpart V contains
alternative provisions exempting valves fror;1 routine monitorino requi^eiTie'"! ;s
if an annual test demonstrates that less than 2 percent of valves are leakirn.
Comment Additional Equipment Requirements Under Subpart V
Three commenters (IV-D-1, IV-D-8, IV-D-9) noted that the EPA's conclusion
that all equipment except valves and flanges are already controlled to a
level consistent with Subpart V is not adequately reflected in the proposed
regulation. The commenters recommended that the inconsistencies in require-
ments of Subpart V and the VC standard be clarified by listing which
requirements apply to specific equipment.
In particular, several commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4)
pointed out that Subpart V contains requirements for sensors on pump seals
not found in the VC standard and that under the revised standard, plants
would be required to retrofit pumps with seal sensor devices at significant
cost. One of the commenters (IV-D-3) also stated that compliance with the
open-ended valve requirements of Subpart V would require retrofit expenditure.
Another commenter (IV-D-2) expressed concern about the cost of performing
annual leak checks on valves, many of which are reportedly difficult to
access. Three commenters (IV-D-1, IV-D-2, IV-D-4) stated that the area
monitors operated under the VC standard provide adequate leak detection for
seal failures.
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Response
As stated in the preamble to the proposed revisions (50 FR 1191),
addition of Subpart V to the VC standard substantively affects only valves
arc flanges in VC service. Kore specifically, ever, though Subcart V ",<•;: "I
requirements in Subpart F, p'ants complying with the e^uicrr.er.t e.nc '.-,cr'<
practice requirements of Subpart F for equipment components other than valves
and flanges should automatically comply w'th the Subpart V provisions.
Requirements in 40 CFR 61.65(h^ of Subpart F for valves, purps, compressors,
Despite the concerns raised by the commenters, this conclusion is sti'1
judged by EPA to be essentially correct with the following exception.
For those plants that have not already adopted the usual industry
practice of capping open-ended lines, Subpart V will require these lines to
be capped. Capping of open-ended lines is required both in Subpart V for
controlling equipment leaks of volatile hazardous air pollutants and in the
SOCMI equipment leak standards (40 CFR Part 60 Subpart VV). In both cases,
capping open-ended lines was judged to be a cost-effective method for elimi-
nating leaks from open-ended lines. The cost effectiveness of capping
open-ended lines is about $400/Mg VOC. The EPA believes this finding also
applies to most open-ended lines in VC service. However, EPA investigated
the retrofit expenditure for capping open-ended lines at the plants operated
by Commenter IY-D-3 and found that certain open-ended lines resulting when
multi-purpose lines used to charge materials tc polymerization reactors in
PVC plants are in VC service (i.e., charging VC) may be unreasonable to cap,
because of the high cost associated with additional piping and other retrofit
requirements (Docket Items IV-C-9, IV-B-10). For this reason, EPA has
decided to exempt certain open-ended lines in batch operations from the
requirements of Subpart V.
The basis for the comment that compliance with Subpart V would require
plants to retrofit their VC service pumps with seal sensors is unclear. The
VC standard requires plants to minimize emissions from seals on pumps in VC
service by installing sealless pumps, pumps with double mechanical seals, or
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equivalent. Plants choosing to meet the requirement by installing pumps with
double mechanical seals are required to maintain the pressure between the two
seals so that any leak that occurs is into the pump cr by ducting any VC
between the two seals to the primary contro1 device. In order to ascertain
proper operation of these seal systems, seme method of ^o-^tcr "°;; :•", a :cf"-r-'
fluid is essential. To the EPA s Kr,cv ledge, area-wide ^CT^cring is •:",".<
effective for detecting large leaks and cannot be relied upon to indicate the
need for repair of seal systems prior to catastrophic fa-'lure. Infornat-or
from several PVC plants about their seal systems indicates a range of
monitoring metnocs 7<"GiT a sior<~ q'ass marking -he "eve! O"" fi'j'-o i •'• ~ "-
barrier fluid pot to a pressure gauge measuring the nitrogen paa used ~c
maintain the barrier fluid at a positive pressure to the pumped material.
The EPA considers these types of methods of monitoring the seal system to be
adequate for meeting the Subpart V requirements for seal sensors on pumps
with double mechanical seals.
Comment Approval of Existing Plans
Three commenters (IV-D-1, IV-D-3, IV-D-4) questioned the requirements
for obtaining approval for leak detection and elimination programs. One
commenter (IV-D-4) recommended that resubmission of plans be required only
if plants modify their plans. The second commenter (IV-D-1) recommended that
already approved plans be exempt from resubmittal requirements. The commenter
(IV-D-1) suggested that the standard specify that plans submitted for approve1
that are not acted upon within 60 days will be considered approved.
The third commenter (IV-D-3) questioned whether effective existing leak
detection and elimination programs would be deemed equivalent to Subpart V if
they did not contain the extensive administrative requirements of Subpart V.
The commenter added that past experience in submitting equivalency requests
has indicated that significant man-hours are required to prepare an acceptable
equivalency request.
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Response
The commenters misinterpreted the meaning of the provision in proposed
40 CFR 61.65(b)(8) which introduces criteria for approval of "leak detection
and elimination plans. The EPA does not intend for plants to resubmit plans
already approved under the origina1 standard. Only new or modified pl^ns are
reouired to be submitted for approval under the revised standard. E?H v; :'
use Subpart V, as an aid, when evaluating compliance with requirements for
pumps, compressors and other equipment components. However, compliance with
the VC standard requirements (in 40 CFR 61.65(b)(8)(3)) for these equipment
components represents compliance with Subpart V. "Equivalency1 of existing
leak detection and elimination programs with the Subpart V requirements may
be demonstrated, through a performance test of valves as prescribed in proposed
40 CFR 61.61(b)(8)(ii). This does not apply to equipment requirements for
pumps and other equipment or the performance standard for leaks from pressure
relief devices.
Comment Basis of Subpart V Requirements
The commenter (IV-D-3) stated that the emission reductions projected for
Subpart V are based on refinery fugitive data and are not accurate for the VC
industry which is a low-leak industry.
Response
Subpart V was developed based on leak studies for VOC, in general, and
benzene, specifically. As noted by the commenter, these studies were performed
at petroleum refineries. However, EPA investigated other leak studies per-
formed in the synthetic organic chemical manufacturing industry (SCCMI) in
developing equipment leak standards for SOCMI. (Vinyl chloride production is
part of SCCMI.) The SOCMI equipment leak standard (40 CFR Part 60 Subpart
VV) contains the same equipment and work practice requirements as Subpart V.
The differences between petroleum refinery and SOCMI leak data were found to
be unimportant in developing standards for these industries.
In addition, Subpart V contains a provision for low-leak plants such as
some of the plants in the VC industry (see 40 CFR 61.243). This provision
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allows plants that have demonstrated their low-leak status to monitor for
leaks on a less frequent basis and therefore significantly reduce the cost oj
controlling equipment leaks to the required level.
Comment Subpart V 2 Method 21 - Notice for Pev-'e",1
The commer.ter '11-0-9) stated that EPA should issue a notice allowing
for public review and comment on Subpart V and EPA Test Method 21 as they
apply to VC.
Response
Comments on Subpart V and EPA Test Method 21 as they apply to the VC
standard have been considered in developing the promulgated standard for VC.
A separate notice is not needed. Responses to specific comments on Subpart V
and Method 21 as they apply to VC are included in Sections 2.3.7 and 2.3.8.
2.3.3 Alternative Compliance Demonstration Option
Comment VOC Service vs. VC Service Components
Four commenters (IV-D-1, IV-D-4, IV-D-8, IV-D-9) requested that the
provision allowing plants to demonstrate equivalency of leak detection and
elimination programs with Subpart V through a performance test specify a
sample of VC service valves to be tested instead of VOC service valves. Two
of the commenters (IV-D-8, IV-D-9) stated that testing of VOC service valves
is inappropriate under a standard regulating VC.
Response
The EPA agrees that specifying a performance test of valves in VC
service would be more appropriate for demonstrating the effectiveness of a
plant's leak detection and repair program for controlling VC leaks. Subpart V
already includes an option for plants to demonstrate their program's effec-
tiveness through an annual performance test of VC service valves (see
40 CFR 61.243). However, in response to concerns raised by industry represen-
tatives, EPA recognized if a performance test of VC service valves is
2-30
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prescribed, some plants would have to identify, tag and keep a record of all
VC service valves for the first time. At the August 30, 1984, meeting o^ tue
National Air Pollution Control Techniques Advisory Committee (NAPCTA.C),
industry representatives voiced opposition to inventorying eruipment component:
for purposes o~ ~ed,<, :escirc :ecause of the ac;di tiontJ adiTn'r.i s'-r^.'.: •. e :.,-•'.-:••
associfitee witn tacging equiprent ana maintaining records. Tr,e £:- ~e:' -v~?
this administrative burden can be reduced without affecting the level of
control exoected to be demonstrated during the performance fast by al "o'.v'r:'~
plants tc test a sample of valves in VOC service which are more readily
iclenti*~"i6b'e . ~'ie EP^'s '"£•:"'$'! on "c so^c'fy a performance test _,~ , 1C
service valves is based on tne assumption that if 2 percent cr less o" ~"e
tested VOC service valves are leaking, it is reasonable to expect that
2 percent or less of the VC service subset of these valves are leaking.
Based on these considerations, EPA sees no reason to revise this provision.
Comment Leak Criteria
Two commenters (IV-D-8, IV-D-9) recommended that the provision allowing
plants to demonstrate equivalency of existing leak detection and elimination
programs with Subpart V through a performance test specify that instrument
readings exceeding the plant's approved leak definition be used as the leak
criteria rather than instrument readings greater than 10,000 ppm as specified
in Subpart V. The commenter stated that use of the plant-specific leak
definition would be more consistent with the provision requiring plants to
develop leak definitions as part of their leak detection and elimination
programs.
Response
The commenter apparently believes that if a performance test is to
demonstrate the effectiveness of existing leak detection and repair programs
practiced by plants relative to the Subpart V requirements, it should be
based on the leak definition implemented as part of the existing program. In
contrast, EPA believes that demonstration of effectiveness of existing
programs [relative to Subpart V] can be achieved only with a performance test
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on valves using the leak criterion in Subpart V (i.e., instrument readings of
greater than 1C,COO ppm at the interface based on calibration with methane).
In fact, using the Subpart V leak criterion during the performance test is
more appropriate then using the plant-specific definitions because of differ-
ences in piant-scec".~ic leak cefinitions v.'hic'n contribute re \~e~~-^~';±
programs. Use of a stancaro ~ ea'< criterion ensures that the c- r^cr^anci "~~G ~.
is applied with equal stringency at all plants throughout the industry.
Plants may request J'haf existing leak definitions established as oar1: of
their plant-specific programs be allowed for use during performance tests.
I'se OT the plc|rT-spec'i'~"c "•eak oef'Tif">oro wiV be al'iowec ~? t"6' a^e
demonstrated tc be more stringent than the leak criterion found :r, Subpart V.
Comment Number of Valves Required to be Tested
Three commenters (IV-D-4, IV-D-8, IV-D-9) requested clarification
regarding the number of valves required to be tested as part of the perform-
ance test to demonstrate equivalency of leak detection and elimination
programs with Subpart V.
Response
The provision in proposed 40 CFR 61.65(b)(8)(ii)(B) prescribing the
performance test states that "a minimum of 2CO or 90 percent of the total
valves in VOC service" within each process unit are to be tested. Specifi-
cally, process units with more than 200 valves in VOC service are required to
test at least 200 valves while process units with less than 200 valves in VOC
service must test 90 percent or more of valves. Accordingly, the provision
has been clarified:
§61.65(b)(8)(ii)(B)
"For each performance test, a minimum of 200 or 90 percent, whichever is
less, of the total valves . . . . "
Comment 30 Day Retest & Annual Option
Four commenters (IV-D-1, JV-D-3, IV-D-4, IV-D-5) suggested that plants
failing to demonstrate equivalency of existing leak detection and elimination
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programs with Subpart V through a performance test be allowed to retest
within 30 days rather than become automatically subject to all Subpart V
requirements. Commenter IV-D-2 added that a retest would provide incentive
for plants to evaluate and correct problems prior to the retest to avc^'d
becoming subject to Subpart V. Commenter IV-D-4 explained that r retest ~'s
appropriate considering the time required to implement Subpart V. Tv.c
commenters (IV-D-1, IV-D-3) also recommended that plants be allowed the
option of reverting back to the existing leak detection and elimination
programs after a year' under Subpart V.
One ccmmenter (IV-C-Sl recommended dropping inclusion of Subcart
requirements in the VC standard, but maintaining the proposed provision
requiring plants to demonstrate the effectiveness of their existing leak
detection and elimination program through an annual performance test.
Response
The changes recommended by the commenters are not consistent with the
purpose for adding Subpart V to the VC standard. The VC standard, as revised,
requires plants to implement an effective leak detection and elimination
program for valves either by complying with Subpart V or by following their
existing program if it results in fewer than 2 percent leaking valves. As
discussed above, other requirements of Subpart V will be used to supplement
compliance determinations with §61.65(b)(8). In the EPA's judgement, a
performance test measuring greater than 2 percent leaking valves is indicative
of an inadequate existing program. Consistent with the purpose of adding
Subpart V, it is appropriate to reauire these programs to be upgraded to
comply with Subpart V requirements because they represent an effective
program for detection and repair of leaks from valves.
The performance test on valves is a convenient and efficient way for
plants to demonstrate the effectiveness of their existing leak detection and
elimination programs without the additional burden of inventorying equipment
components and maintaining records. However, once failure of a performance
test triggers Subpart V and the associated inventory and recordkeeping
requirements, the benefit of the convenient and efficient performance test
-------
option no longer exists. However, under Subpart V, monitoring of valves may
also be limited to an annual performance test as long as 2 percent or fewer
valves are found to leak.
Comrr.ent Impact of Performance Test
Two comrr.enters (IV-D-3, IV-D-4^ recoirn.ended that -failure by plants
demonstrate through a performance test that fewer than 2 percent of valves
leak shouTd trigger Subpart V requirements for valves only and not c^her
equipment components.
Response
The commenters' concern is not relevant because plants complying with
the equipment leak provisions of the VC standard already meet the Subpart V
requirements for equipment components other than valves and "Hanges, with the
possible exception of open-ended lines. (As discussed in Section 2.3.2,
plants not currently complying with the open-ended line requirements in
Subpart V will have to cap these lines. Capping of open ended lines is
considered by EPA to be a cost-effective method for controlling leaks from
open-ended lines.) In addition, the requirements of Subpart V will only be
used to supplement determinations of compliance with §61.65(b). If compliance
with Subpart V is not demonstrated by a plant, the plant does not comply with
Subpart F.
2.3.4 Leak Definition
Comment Clarification of Leak Definition
Three commenters (IV-D-4, IV-D-8, IV-D-9) requested clarification
regarding the requirement that plants establish a leak definition as part of
their leak detection and elimination program. Two of the commenters (IV-D-8,
IV-D-9) recommended that the provision requiring plants to establish a leak
definition as part of their leak detection and elimination program indicate
whether the leak definition applies to both area monitors and to portable
monitors, or just to area monitors. The third commenter (IV-D-4) recommended
modifying the provision requiring establishment of a leak definition to
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require plants instead to define a Teak level in conjunction with area
monitors such that area monitor readings in excess of the defined level are
not considered leaks in themselves but rather an indication to search for a
"leak" as now defined by the criteria cf Subpart ".
Response
Under the original VC standard, plants are required to define a leak as
part c~ the^'r program for detecting and eliminating equicntr^ leaks, -1 ">-,'.;:
different approaches were taken by plants, the intent was ^cr plants to
background concentrations, inen, when portable monitors we^e used ~c pin-
point leak sources, a different leak definition was to be applied. Because
of differences among plants in the number and location of area monitors and
background concentrations, leak definitions pertaining to area monitor
detections necessarily vary and should remain a plant-specific measurement.
However, both the industry and EPA may want to review and alter the area
monitor leak definitions to improve their usefulness.
Unlike the leak definition for area monitors, the definition used to
measure leaks from specific equipment components can and should be standard-
ized. Addition of Subpart V to the VC standard provides this standardiza-
tion. As a result, plants no longer are required to develop their own leak
definition for detecting leaks with a portable monitor.
In response to the comment that leeks defined in conjunction with area
monitor detection of leaks should be considered an action level indicating
the need to search for a leak, it. should be pointed out that a reading in
excess of the area monitor leak definition is an indication of a leak. Even
if the actual source of the leak is not found, the event is recorded as a
leak for compliance purposes.
2.3.5 Relief Valve Monitoring Requirements
Comment Rupture Disc Exemption
Three commenters (IV-D-3, IV-D-8, IV-D-9) requested that relief valves
equipped with rupture discs be exempt from the proposed monitoring requirements
-------
for relief valves. Commenter IV-D-9 further recommended that relief valves
connected to a process line, recovery system or equivalent be exempt fron
relief valve monitoring requirements. The commenters recommended that
Subpart V be revised accordingly.
Response
Section 112 of the Clean Air Act requires EPA to set performance
standards, whenever -Feasible. In the case of relief valve ""eaks, it is
possible and acpropriate for a performance standard to be applied. Further-
more, the -P& does rot agree thai onlv eQuioc^a re lip- --e^es "r>~';> fip~;r"c
discs is adequate basis for exempting relief valves from monitoring requ're-
ments for leaks. As part of good operation and maintenance practices,
rupture discs should be checked at least annually and after each discharge to
maintain their integrity. The best way to ensure that integrity of the
rupture disc is constantly maintained is through the performance test in
Subpart V.
The EPA agrees that venting a relief valve through a closed vent system
to a control device warrants exemption from monitoring requirements. The
Subpart V requirements referenced in the VC standard for controlling equip-
ment leaks from relief valves already exempt relief valves connected through
a closed vent system to a control device from monitoring requirements. In
this situation, process lines or recovery systems may qualify as control
devices for the purpose of complying with Subpart V.
2.3.6 Calibration Requirements
Comment Calibration Gas for Monitors
Two commenters (IV-D-8, IV-D-9) requested clarification on calibration
gas requirements for monitors under the revised standard. Commenter IV-D-9
recommended that the standard specify continued use of VC as calibration gas
instead of methane or hexane as prescribed in Subpart V.
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Response
There are two different definitions of a leak, and thus two different
calibration gas requirements. Leaks are detected in two different ways: by
an area monitor specific to VC measuring the general condition or possible
presence cf VC leaks -'n an area; and by routire leak detection monitoring ''of
particular valve or purr.p seels, etc.) to determine if specific pieces o'~
equipment are leaking.
The area monitor must be specific to and calibrated with VC because
other organics may be present in the air to such an extent that the VC
concentration would be masked, i.'hether the routine ""eak defection rror. i~or is
calibrated with VC or some other organic is not as critical tc EPA as long as
that monitor is less responsive to VC than the alternative calibration gas.
If such a monitor is calibrated with VC, then the definition of a leak is in
effect lowered, and EPA would consider that acceptable in an alternative
method request.
Comment Monitor Span Checks
Two commenters (IV-D-8, IV-D-9) suggested that because the same
instruments are often used for both area monitoring and exhaust gas moni-
toring, a single span check using a 10 ppm VC standard should be allowed
instead of two separate span checks.
Response
Area monitoring and exhaust gas monitoring serve two different regulatory
purposes within the standard. While a 10 ppm span is appropriate for emission
monitoring for the exhaust gas standard, it may or may not be appropriate for
area monitoring, depending on the background concentration of VC in the areas
of the plant to be monitored. Therefore, while the same instrument may be
used to serve both monitoring requirements, there is no regulatory justifica-
tion for requiring that the required span gases be the same concentration.
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2.3.7 Subpart V
Comment Exemption from Administrative Requirements
Two commenters (IV-D-8, IV-D-9) requested that a provision be added to
Subpart V allowing exemption from certain inventory and recordkeeping recip'r
ments for values if a performance test indicates tha^: 2 percent or -ewer
valves in VHAP service are leaking. Commenter IV-D-8 also recommence tnat
similar provision be added to Subpart VV.
Response
Subpart V of Part 61 and Subpart VV of Part 60 already contain a prcvis1
which allows plants that establish a low valve leak rate (i.e., less than
2 percent) to skip monthly monitoring and to perform monitoring on an annual
basis. This differs from the provision in the VC standard that exempts
plants that initially, annually, and at the request of EPA, demonstrate a
2 percent or better leak rate from certain inventory and recordkeeping
requirements. Exempting VC plants that consistently demonstrate a low leak
rate from these inventory and recordkeeping requirements is reasonable
because these plants have over eight years of operating experience under
formal leak detection and repair plans required by the original VC standard.
Special consideration should be given to those plants for their successful
efforts in response to the original VC standard requirements. Because other
plants subject to 40 CFR Part 61 Subpart V and 40 CFR Part 60 Subpart VV do
not have this level of experience nor have they been subject to a prior NSPS
or NESHAP for equipment leaks, it is reasonable to require these plants to
comply with all the requirements under Subpart V.
Comment Equipment Identification
The commenter (IV-D-8) recommended that Subpart V be revised to also
allow identification of equipment by labeling on engineering drawings rather
than only tagging in the field.
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Response
Methods other than tagging in the field are currently allowed ^or
identification of equipment components for testing purposes. However, more
detail thar ^s tyrr;cal~!y available on engineering drawings is often required.
For ex^cle, onctc-""5ox3 c~ ec1.. "'onenc c opponents or o^her idcr;t~ "1' zz~.~, cr :::~
may be necessary tc ensure t>'c~ inspectors and plan~ personnel are ae;e ".:•
find the location of all eauipment components subject to Subpart V
requirements.
Comment ""ange '.c^~~~': >:?~''.••
The commenter i'IV-D-8) stated that Subpart V should clearly specify tr.at
only flanges which have been found to be leaking are required to be identified.
He noted the difficulty and expense in identifying every flange because many
are covered with insulation.
Response
Flanges need to be identified to ensure effectiveness of the leak
detection and repair requirements of Subpart V. However, EPA recognizes that
identification of covered flanges and other connectors according to the
inventory requirements in Subpart V could be too costly. Thus, in response
to this comment, EPA has decided to add a provision to Subpart V allowing
plants to forego identification of covered flanges. In addition, Subpart V
is being revised to exempt all other connectors from identification and
tagging requirements. However, these connectors-are still subject tc leak
detection and repair requirements.
Comment Valve Repair
The commenter (IV-D-8) stated that valves which have undergone repair
during a shutdown and which are found to still be leaking after startup
should be considered a new leak and not an extension of the first leak,
providing proper repair techniques were applied. The commenter explained
that the success of the repair often can be tested only under operating
conditions.
2-39
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Response
The ccmmenter's recommended approach is already allowed. In these
cases, a review of the repair efforts is made by EPA. If they are judged to
be proper, then the subseauent leak would be a new leak.
Comment
process
The commenter (IV-D-3) requested that the Subpart V provision regulating
process accumulators be modified to specify that /ents arc! ret all fi^it^e
sources on process accumulators in VHAP service are required to be controlled.
Response
The process accumulator vent standard in Subpart V is not applicable to
PVC and ECC/VC plants because these vents are already regulated under the VC
standard by the more restrictive requirements of the exhaust gas limits.
However, valves and other equipment components associated with process
accumulators in VHAP service are intended to be controlled like other VHAP
service equipment components under Subpart V, and consequently, under the VC
standard.
Comment Connector Definition
Two commenters (IV-D-8, IV-D-9) stated that the definition of connector
in Subpart V as it applies to VC should clearly exempt welded joints which
are permanent.
Response
Subpart V already contains the recommended exemption.
2.3.8 Method 21
Comment Sample Flowrate
Two commenters (IV-D-8, IV-D-9) pointed out that the nominal sample
flowrate requirement of one-half to 3 liters per minute in EPA Test Method 21
should be deleted because a response time equal to or less than 30 seconds is
specified in a separate provision. The commenters explained that certain
reliable instruments are precluded by the flowrate requirements.
2-40
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Response
Method 21 includes a flowrate specification specifically to exclude from
the method those types of monitors that have a large or unccnfined sample
inlet area, because EPA found that these instruments were net sufficiently
responsive to leaks of a magnitude that EPA expects tc be identified and
corrected.
Comment Probe Placement
Two commenters (IV-D-8, IV-D-9) requested that EPA Test Method 21 be
revised to specify that equipment components are tc be monitored by placing
the probe inlet within 1 cm of the component interface rather than directly
on the surface of the interface.
Response
Method 21 for measuring VOC leaks from fugitive emission sources specifies
that the portable monitor is to be placed on the surface of the interface to
be tested. In the case of rotating equipment such as pumps, a distance of
1 cm between the probe inlet and equipment interface is specified. The leak
definition specified in conjunction with Method 21 is based on data collected
by placing the sample probe directly on the surface of the interface (except
for rotating shafts on pumps and compressors). In the EPA's judgment, changing
the sampling distance to 1 cm for all equipment components is inappropriate.
2.4 DEFINITIONS
2.4.1 In VC Service
Comment Reason for Revising "In VC Service" Definition
Three commenters (IV-D-1, IV-D-4, IV-D-14) recommended modification to
the revised definition of "in VC service" and to the related provision in
proposed 40 CFR 61.67(h) which describes how to determine whether equipment
is in VC service. One of the commenters (IV-D-14) stated that the rationale
for changing the definition of "in VC service" and adding requirements for
determining whether equipment is in VC service has not been adequately
2-41
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explained and that the existing definition should be retained because it is
clear and workable. The corrmenter (IV-D-14) also pointed out that certain
pieces of equipment alternate in and out of VC service, depending on the
operation being conducted.
Response
During the review of enforcement, and compliance experience under the VC
standard. EPA found *hat the classification of "in VC service" is a point of
contention between regional compliance and industry personnel (Docket Hem
II-A-19'. The EPA concluded fhat the definition of "in VC service" needed
clarification to ensure that all equipment capable of emitting VC is identi-
fied and that the burden of identification falls on plant personnel and not
Regional compliance personnel. To achieve the desired clarification, EPA
adopted the approach for identifying equipment in VHAP service developed for
the Subpart V regulation for equipment leaks. In Subpart V, a definition for
"in VHAP service" is given along with a method for determining whether
equipment is in VHAP service. The VHAP provisions effectively place the
burden on plant personnel to identify all equipment capable of emitting VHAP.
The EPA believes that adoption of the "in VHAP service" provisions of Subpart V
in the VC standard is reasonable and appropriate and that changes to these
provisions in context of the VC standard are not warranted.
The concern raised by the commenter regarding equipment that alternates
in and cut of VC service is apparently directed toward polymerization reactors
and other vessels and equipment that normally contain VC but are occasionally
purged prior to opening for routine or emergency maintenance. The VC standard
contains specific requirements for minimizing emissions during reactor and
equipment opening. Discharges from equipment not in VC service do not
contain VC and therefore are not intended to be regulated by the standard.
The provision regulating relief valve discharges has been clarified to apply
to discharges containing VC to the atmosphere from relief valves on equipment
in VC service. The provision has also been clarified to more adequately
address equipment used in batch processes by referring to contained volumes
in addition to process fluid streams.
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2.4.2 EDC and VC Purification
Comment Clarification of Covered Equipment
Five commenters (IV-D-1, IV-D-3, IV-D-4, IV-D-5, IV-D-14) requested
clarification of equipment covered by the rev'sec1 definition of EDC ourifica-
ticr,, Dart i c'j"1 ar 1 v st^raae ~3.r,
-------
for the original standard that purification equipment containing VC were
intended to be covered by the standard. Curing the review of the standard,
EPA learned that different interpretations of the definitions of EDC and VC
purification had been applied by industry personnel with the result that some
plants vere con-robing erriss^cns ~ro~>, a"" equip-nen- ^ n the CL,rr'"cat:Lr
processes, incluaing storage tanks while others were control" inq on"'.' trv
major emission sources (i.e., finishing columns). Interpretation cf these
definitions also varied among compliance personnel. In particular, octroi iano?
personnel were concerned that some plants interpreted the definition of VC
curifi cation such t'nat control of emissions ^ni VC storage fo"'
-------
final finishing column is not cost effective and that regulation of these
tanks under the VC standard is not warranted.
Although the standard under review regulates VC emissions, EPA considered
the benefit of controlling other VOC, primarily EDC, in its decision regarding
whether to regulate these tarks under the VC standard. Many o" these tan'xs
are already controlled for VOC (dud thus VC; according to state SIP provisions.
The remainder of these tanks are located primarily in attainment areas where
less stringent VOC regulations apply. Moreover, EPA is currently investigating
EDC emissions for possible regulatory development as a hazardous air pollutant
under Section IIP:. The potential emission reduction associated ;-n~\i cor.:,ro*
of EDC storage tanks would amount to about 6GO Mg/yr and the resulting cost
effectiveness would be about $330/Mg EDC (Docket Item IV-B-8). Intermediate
and final EDC storage tanks which follow the final finishing column would
likely be regulated under an EDC regulation. The EPA concluded that regulation
of these storage tanks would be more appropriately carried cut by these other
regulatory mechanisms.
2.4.3 Relief Valve
Comment Exemption of Nonventing Pressure Control
Systems
Four commenters (IV-P-1, IV-D-4, IV-D-9, IV-D-14) requested additional
clarification to the definition of relief valve. Two of the commenters
(IV-D-1, IV-D-9) requested that relief valve be defined as any pressure
relief system used to protect process components from overpressure conditions
by venting directly to the atmosphere. The commenters further recommended
that the definition of relief valve explicitly exempt pressure control
systems such as reaction shortstop systems, refrigerated water systems and
other systems which act to reduce pressure by means other than venting to the
atmosphere. The third commenter (IV-D-4) stated his understanding from past
discussions with EPA that the nonventing pressure control systems are not
intended to be covered by the definition. The commenter (IV-D-4) also
recommended that the definition be modified to exclude all devices controlling
flow around an incinerator, not just control valves. The fourth commenter
>-45
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(IV-D-14) stated that although the revised relief valve discharge standard
eliminates the most significant problem in the original regulation, additional
clarification to the definition of relief valve in proposed 40 CFR 61.61(v)
is reeded to adequately reflect the expressed intent in the preamble
^50 FP 1192). The concenter recommended that- the definition specifically
identify all types of relief devices that are subject to regulation as relief
valves. This clarification would eliminate vagueness arid achieve consistency
with the preamble.
Response
One purpose of defining relief valve is to aid in identification of
emissions of VC to the atmosphere which are subject to the relief valve
discharge standard. The commenters' concern that the definition of relief
valve could be interpreted to include shortstop systems and refrigerated
water systems is irrelevant because it is difficult to conceive that VC could
be emitted from these pressure control systems to the atmosphere. Nonetheless,
EPA has revised the definition of relief valve to explicitly exclude shortstop
systems and refrigerated water systems. However, the promulgated definition
has not been revised to exempt all pressure control systems that protect
process components from overpressure conditions by methods other than venting
directly to the atmosphere. The EPA believes that exemption of all nonventing
pressure control systems would be inconsistent with the intent that discharges
from gasholders or other containment systems to which relief valve discharges
may be vented are subject to the relief valve discharge standard.
The definition of relief valve has also been revised as recommended to
exclude all devices controlling flow around an incinerator, and not just
control valves. These pressure control devices act to bypass exhaust gas
around the incinerator in the event of overpressure conditions or incinerator
malfunction. .Bypassed exhaust gas is subject to the 10 ppm exhaust gas
standard and not to the limits for relief valve discharges unless the bypass
is caused by a relief valve discharge.
Finally, the definition identifies several types of pressure relief
devices which are to be considered "relief valves" when evaluating compliance
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with the relief valve discharge standard. As explained in the preamble to
the proposed revisions (50 FR 1187), this definition is necessary to clarify
that the relief valve discharge standard applies not only to emissions from
pressure relief valves but to other types of pressure relief devices as well.
>. acdiu^on to the lib ted equipment, ^he defirrticn also stages th;;t ;-.:,,
other pressure relief systems that function in the same way (i.e., to protect
process components from overpressure conditions) are to be considered relief
valves. In this v/ay, the indent that all pressure re"""ef devices, arc1 re4"
just certain types, are subject to the relief valve discharge standard is
emphasized.
Comment "Relief Valve" vs. "Relief Device"
Two commenters (IV-D-8, IV-D-9) suggested that the term "relief valve"
be changed to "relief device" to be consistent with the American Society of
Mechanical Engineers (ASME) designation and common usage and to avoid the
confusion of referring to a rupture disc as a valve.
Response
The commenter is correct in noting that "relief valve" is a more narrow
term than "relief device" and that "relief device" better connotes the
variety of pressure relief equipment subject to the VC standard. However,
most pressure relief discharges from equipment in PVC and EDC/VC plants occur
through relief valves. As a result, the original standard was written in
terms of "relief valve" for convenience even though other relief devices were
intended to be included. In order to clarify that all pressure relief
devices are subject to the relief valve discharge standard, a definition of
relief valve has been added. The EPA believes that the added definition
provides a less cumbersome solution for clarifying equipment subject to the
standard than the commenter's suggestion. Nonetheless, EPA appreciates the
confirmation by the industry commenter indicating understanding of the broad
use of the term "relief valve".
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2.4.4 Leak
Comment "Leak" Definition
One commenter (IV-D-14) recommended that the definition of leak be
revised to distinguish what a leak is from events that suggest the presence
Response
As discussed in the preamble to the proposed rev's ions (50 PR 119?}, ore
purpose of adding a definition of leak to the VC standard is to help dis-
tinguish v'C emissions resnltinc ^rorr ''leaks ' ^rom '*'C 0:?isc^^ri • •,-,-,ir-.~- .-.•- ^^
relief valve discharges and exhaust gas. To achieve this purpose, the
definition of leak lists events regulated by the VC standard and Subpart V
(incorporated in the VC standard by reference) which indicate a need for
repair or further action on the part of plant owners or operators. As
explained in responses to other comments, EPA believes that each of the
regulated events listed in the definition represent adequate criteria for
requiring repair or further action and are appropriately included in the
definition.
Comment Indications of Liquid Dripping
Six commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4, IV-D-8, IV-D-9^
recommended modifications to the portion of the leak definition pertaining tc
indications of liquid dripping. Four of the commenters (IV-D-1, IV-D-3,
IV-D-8, IV-D-9) stated that indications of liquid dripping should be considered
leaks only if confirmed by an objective measurement. Commenter TV-D-3
suggested that an instrument reading greater than 10,000 ppm be the criterion
for establishing that dripping liquids are VC leaks. Commenters IV-D-8 and
IV-D-9 recommended that barrier fluid levels and/or pressures be relied upon
instead as indicators of VC leaks from double mechanical seal pumps. Commenter
IV-D-4 suggested that leaks defined as indications of liquid dripping should
be limited to liquid dripping from pump seals in VC service. Commenter
IV-D-2 recommended deletion of indications of liquid dripping from the leak
definition on the basis that drips from pumps are likely not VC.
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Response
The EPA believes that indications of liquid dripping is appropriate
criterion for requiring repair actions on double mechanical seal pumps in VC
service and should therefore be included in the definition of leak. Visible
leakage from all types of pump sea's, inducing double rechanical see^s
required by the \.'C standarc, is genera "My indicative of seal wear even i ' nc
VC is present in the leaking fluid. To prevent further seal wear resulting
in catastrophic seal failure accompanied by VC emissions ^o the atmosphere,
the seals should be repaired soon after leakage is initially detected. The
same leak criterion for double mechanical seal pumas is prescribed in •Ecu^me-",;
leak standards for SOCMI and benzene. In the VC standard, the portion of the
leak definition referring to indications of liquid dripping applies only to
pumps in VC service.
Barrier fluid level and pressure sensors also provide indication of
certain types of seal wear and are thus included in the Subpart V require-
ments for detecting leaks from double mechanical seal pumps. In the EPA's
judgment, monitoring of barrier fluid as well as dripping liquids is necessary
to ensure control of equipment leaks from pumps with double mechanical seals.
Comment Sensor Detection of Seal Failure
Three commenters (IV-D-1, IV-D-2, IV-D-4) disagreed with inclusion of
"sensor detection of failure of a sea"1 system" in the definition of leak.
Two of the commenters 'IV-D-1, IV-D-2) explained that seal system failures
are not necessarily indicative of VC leaks to the atmosphere. The third
commenter (IV-D-4) stated that sensor detection of seal failures should be
deleted from the definition of leak in conjunction with the recommended
removal of proposed seal monitor requirements for pump seals.
Response
As in the case of indications of liquid dripping, EPA believes that
sensor detections of seal failure (i.e., detection of a rapid change in
barrier fluid leve"i or pressure) is appropriate criterion for requiring
repair actions for double mechanical seal pumps in VC service and should be
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included in the definition of leak. Although failure of an inner seal on a
double mechanical seal pump in VC service may not result in direct emission
of VC to the atmosphere, continued operation would result in total seal
failure accompanied by direct emission of VC to the atmosphere. The eoinpn^ent
leak standards for SCC'-'I and benrene also list sensor detection of sea"1
failure as a criterion requiring repair actions for double mechanical seal
pumps.
The EPA is net exempting double mechanical seal pumps in VC service frcrr.
seal monitoring requirements in Subpart V. The basis for this decision is
described in Section 2.3.2.
Comment Leak Definitions Under Existing Standard
Five commenters (IV-D-1, IV-D-3, IV-D-4, IV-D-8, IV-D-9) requested
clarification of the status of leak definitions established under existing
leak detection and elimination programs. Commenter IV-D-1 recommended that
leaks defined under existing approved leak detection and elimination programs
be included in the definition of leak. Commenter IV-D-3 disagreed that
existing leak definitions should be retained under the revised leak definition
on the basis that some plant's existing leak definitions are much lower than
the proposed leak definition and that imposition of Subpart V repair and
recordkeeping requirements for leaks found under these existing, more stringent
definitions would not be justified. Another commenter (IV-D-4) stated that
the definition of leak should not include events regulated in the original VC
standard of detection of ambient concentrations in excess of background
concentration. Instead, these events should be considered an action level
triggering a search to detect leaks on the basis of other defined leak
criteria. Two additional commenters (IV-D-8, IV-D-9) recommended that the
portion of the definition of leak referring to events regulated under existing
plant programs should specifically reference the provision in the existing
standard where these leak events are defined.
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Response
Under 40 CFR 61.65(5)(8)(vi) of the VC standard, plants are required to
establish a leak definition at an acceptable level when compared to the
background concentration. The provision allows -for different leak definitions
to be established in different oa^rs c~ the plant ::ecajse c^ "ar-aticr^ -'-
background concentrations. The provision alsc allows for icjusrrre-i :s ':•:> ~~&<,
definitions over time as background concentrations are reduced. During tne
review o^ the standard. EPA found that leak definitions established <;ir!e»"
this prevision varied widely -^rorn plant to plant (Docket Item II-A-19\
are in part due to the variability among plants in the number and ;cca~icr, or
area monitors and differences in background concentrations. Because of these
factors, it is impossible to establish a standard leak definition applicable
to area monitors.
In the case of detection of leaks using portable monitors, however, it
is possible and appropriate to establish a standard leak definition and
method for detection of leaks. Consequently, the definition of leak in the
VC standard includes specific criteria to be used by plants in place of
existing definitions for identifying leaks with portable monitors. The
prescribed leak criteria is consistent with the criteria developed for
detection of leaks with a portable monitor under equipment leak standards for
benzene and SOCMI and may be more or less stringent than the definitions
established under the original VC standard. The EPA believes that the leak
criteria developed for these other standards represent an effective program
for detection of leaks with portable monitors and that more stringent
definitions are not needed.
Because of the difficulty in establishing standard criteria for
identifying leaks with area monitors, the definition of leak incorporates the
plant's existing definition developed for use with the plant's area monitors.
In reviewing the standard EPA did not identify specific problems with the
definitions of leak pertaining to area-wide monitoring systems in use by the
plants. The EPA concluded that the area-wide leak definitions can appro-
priately serve their purpose. Further, EPA does not intend for changes in
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the standard to interfere with this method of controlling leaks. However, as
discussed in the preamble to the proposed revisions (50 FR 1190), plants have
the option of altering the number of points that are monitored and the
distribution of monitoring locations associated with existing fixed-point
monitoring plans to better complement the nsv^y presc"~':_ec pcrtc^'i r:-""'to'""':":
requi reiiients. The revised portable monitoring leak detection ^ec; : r-rj.er.ts if
conjunction with the fixed-point monitoring requirements will ensure control
of VC emissions from equipment leeks to the level intended by the original
regulation.
Comment Reference to Events anc Emissions
Regulated Elsewhere
One commenter (IV-D-14) stated that reference to events regulated under
Subpart V and under the original leak detection and elimination requirements
in 40 CFR 61.G5(b)(8)(i) of the VC standard is not appropriate in the proposed
leak definition because the referenced regulations do not contain leak
definitions. The commenter (IV-D-14) further stated that the provision in
the proposed leak definition that defines leaks as emissions not specifically
regulated elsewhere in the standard should be omitted because it has no
apparent basis and would be confusing.
Response
For purposes of the VC standard, a leak is defined as those events
regulated under the VC standard and Subpart V (included in the VC standarc by
reference) which indicate the need for repair or further action by the plant.
The definition of leak appropriately references where these events are
regulated (i.e., either Subpart V or the VC standard). The provision in the
definition that leaks include emissions not regulated under certain prescribed
parts of the VC standard was included primarily to help ensure regulation of
VC emissions from sources not addressed elsewhere in the standard. For
example, although uncommon, emissions of VC occasionally occur from sources
such as broken pipes or headers. In the past, it was unclear to some plant
owners and operators whether these types of emissions were subject to
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regulation as exhaust gas, as a leak, as both, or as neither. The proposed
definitions of leak and exhaust gas included provisions intended to clearly
distinguish between the two types of emissions. However, these provisions
were not intended to imply that compliance with requirements for leaks and
exhaust gas would be mutual ""y exclusive. After reviewing the proposed
definitions, it is the EPA's opinion that automatic classification of enrss ~'crs
from unconventional sources such as broken pipes as either a leak or exhaust
gas is neither practical nor appropriate. Accordingly, the provision in the
definition of leak which specifies that emissions not regulated under the
prescribed parts of the standard are to be considered leaks has been delete.
Comment Instrument Readings of 500 ppm Above
Background
Five commenters (IV-D-1, IV-D-2, IV-D-3, IV-D-4, IV-D-9) suggested that
the distinction between leaks defined as instrument readings greater than
10,000 ppm and leaks defined as instrument readings of 500 ppm above background
be clarified by specifying that instrument readings of 500 pprn above background
apply only to certain equipment. Three of the commenters (IV-D-1, IV-D-2,
IV-D-9) recommended that instrument readings of 500 ppm above background be
applied to relief valves when not relieving and sealless pumps. A fourth
commenter (IV-D-3) recommended applying the 500 ppm above background definition
to leaks from sealless valves in addition to pumps and relief valves and the
fifth commenter (IV-D-4) recommended applying the 500 pprn above background
definition to non-relieving relief valves only.
Response
The commenters correctly pointed out that leaks defined as instrument
readings of 500 ppm above background are intended to apply to equipment
designated to comply with no detectable emissions. According to the revised
VC standard, relief valves are to be operated with no detectable emissions.
In addition, valves, sealless pumps and compressors can be designated for no
detectable emissions under Subpart V under certain conditions. To clarify
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the leak definition, it has been revised to clearly distinguish between leaks
defined as instrument readings of 10,000 ppm and leaks defined as instrument
readings of 500 ppm above background as follows:
561.61fw) "Leak" means any of several events ... (4) detectable emissions
as indicated by an instrument reading of greater than 5GC ppn1 above
background "'or equipment designated for no detectable emissions.
Comment Reference to EPP Test Method 21
Two cotnmenters (IV-0-1, IV-D-4) pointed out that leaks defined as
instrument readings cr greater that 10,OCC ppm should be referenced to EPA
Test Method 21. One of the commenters (IV-D-4) also suggested that leaks
defined as instrument readings greater the 500 ppm above background be
referenced to Method 21.
Response
As recommended, the leak definition has been revised to appropriately
reference EPA Test Method 21 as follows:
§6.1.65(w) "Leak" means any of several events ... (1) an instrument reading
of 10,000 ppm measured according to Test Method 21 (see Appendix A of 40 CFR
Part 60) ... (4) detectable emissions as indicated by an instrument reading
of greater than 500 ppm above background for equipment designated for no
detectable emissions measured according to Test Method 21 (see Appendix A of
40 CFR Part 60) . . .
2.4.5 Exhaust Gas
Comment Reconsideration of "Leak" and
"Exhaust Gas" Definitions
The commenter (IV-D-7) stated that unintentional emissions from equipment
components for which emission limits are prescribed should not be considered
exhaust gas, as proposed, but rather be considered as a leak, and requested
that the proposed definitions for leak and exhaust gas be changed accordingly.
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Response
The EPA agrees with the commenter that in certain situations,
"unintentional" emissions from equipment components for which emission limits
are prescribed nr.ay be more appropriately regulated under standards applyino
to ecuior,.ent lea:_ t'J'J
such as valves and pumps. The -acts of the situation, such as tne reason -"or
the emission, its magnitude, and the actions taken to alleviate its impacts,
would be taken into account when determining the applicability of the standard
to a specific incident.
Comment Reference to Limits for Equipment
The commenter (IV-D-14) stated that reference in the exhaust gas
definition to "... equipment for which 10 ppm emission limits are pre-
scribed" is misleading and should be deleted because the cited sections apply
limits to exhaust gas and not equipment.
Response
As pointed out by the commenter, the definition of exhaust gas refers to
several sections in the VC standard which prescribe emission limits for
exhaust gas from various equipment in PVC and EDC/VC plants. In order to
clarify any misunderstanding regarding which emissions are subject to regula-
tion as exhaust gas, the definition has been revised as follows:
§61.61(x) "Exhaust gas" means any offgas ... in direct contact with the
equipment, for which emission limits are prescribed in ...
Comment Reference to Disposition of Exhaust Gas
The ccmmenter (IV-D-14) recommended that the definition of exhaust gas
be revised to omit the words "directly or ultimately" because they do no
contribute to the meaning of the definition.
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Response
The definition of exhaust gas intentionally specifies offgas discharged
"directly or ultimately" to the atmosphere to clearly indicate that the
disposition of the offgas does not affect the applicability of the "exhaust
gas" standards. Vihether tre ericas is ventec ~o the at~o5tuere, /5:;tec TO 2
control device or corrbinec with other offgas strearr.s it is subject to tf;e
"exhaust gas" standards. The EPA believes the woras "directly or ultimately1
contribute meanina and should be retained.
The ccmmenter 'IV-D-14) recommended that t.ne definition of exraust gas
recognize that all emissions which have been treated in a control device
become exhaust gas, regardless of their origin. He recommended alternative
language to identify exhaust gas as the object of control to 10 ppm.
Response
One purpose of adding a definition of exhaust gas to the VC standard is
to help distinguish VC emissions occurring with exhaust gas from VC emissions
resulting from leaks and relief valve discharges. The EPA believes that the
proposed definition better achieves that purpose. Thus, the commenter's
suggestion is rejected.
2.4.6 Relief Valve Discharge
Comment "Relief Valve Discharge" Definition
The commenter (IV-D-7) recommended an alternative definition for relief
valve discharge to replace the proposed definition.
Response
The commenter's recommendation that the definition of relief valve
discharge be expanded to any "non-leak discharge" through a pressure relief
device designated to protect process components from overpressure conditions
is unnecessary. The definition of relief valve discharge adequately serves
the purpose of distinguishing relief valve discharge emissions from VC
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emissions occurring with exhaust gas and leaks. Moreover, the definition of
relief valve specifies that relief valves are pressure relief devices designed
to protect process components from overpressure conditions. Inclusion of
this description of relief valve in the definition of relief valve discharge
is reduncant and unnecessary.
?.4.7 3-Hour Period
Comment Potential for Three 3-Hour Exceedences
of 10 ppm Limit
Five commenters (IV-P-1, IV-D-2, IV-D-4, TV-D-6, IV-D-14) noted that the
definition o~ 3-hour period creates 24 3-hour periods per dey with the result
that a single hourly average in excess of 10 ppm could cause three 3-hour
exceedences of the 10 ppm limit. Two of the commenters (IV-D-1, IV-D-4)
explained that establishment of rolling 3-hour averaging periods effectively
negates the intended clarification that 1-hour averages are not the intended
compliance criteria. Another commenter (IV-D-14) pointed out that only eight
performance tests prescribed under 40 CFR 61.67 could be performed during a
24-hour period. The commenters recommended that the 10 ppm regulations
specify that a single hourly average in excess of 10 ppm can not cause more
than one 3-hour period to be considered in excess of 10 ppm.
Response
The commenters correctly interpreted that the definition of 3-hour
period creates 24 3-hour averages per day. In addition, the commenters
correctly concluded that in cases when the control device fails significantly
causing a 1-hour exceedance of the 10 ppm exhaust gas limit, the result can
be three 3-hour exceedances of 10 ppm. Nonetheless, EPA believes the
definition of 3-hour period is correct and should be retained.
The purpose of specifying a 3-hour average for compliance with the
10 ppm limits for exhaust gas was to improve consistency of the exhaust gas
standards with the performance test requirements which specify an average of
three runs of 1 hour each. The performance test method does not, however,
preclude taking 24 1-hour samples during a 24-hour period.
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Rolling 3-hour periods are necessary to ensure that all 3-hour averages
exceeding 1C ppm are reported. Otherwise, 10 ppm exceedances during two
consecutive hours would only be averaged together if they happened to fall in
the same 3-hour reporting period. Rolling 3-hour periods also help ensure
timely response in correcting periods of excess emissions. In the absence o^
rolling averages, 'nigh readings during the first hour of a 3-hour period
could be left unattended for up to two more hours without influencing reported
results or the actions of operating personnel.
2.5 REVISIONS 70 OTHER PARTS OF Th'E STANDARD
2.5.1 Exhaust Gas Standards
Comment Lower Exhaust Gas Limit Achievability
One commenter (IV-D-12) stated that the EPA's conclusion that the
previously proposed 5 ppm exhaust gas limit should be withdrawn is not
supported by the support document in this rulemaking. The commenter asserted
that the record supports the achievability of the 5 ppm limit by new sources
and by existing sources within 3 years of promulgation. The commenter
pointed to the statement in the 1977 proposal that the 5 ppm limit could be
achieved through the more efficient operation of existing equipment applied
to either new or existing sources. The commenter also stated that the
additional emissions reduction that would be achieved through the use of a
5 ppm standard instead of a 10 ppm standard should not be foregone, given the
carcinogenic nature of VC. Finally, the statement in the preamble that
industry commenters objected to the "zero emission goal" which was the
objective of the 1977 proposal would, the commenter stated, be counter to the
requirement of Section 112 that an ample margin of safety be required.
Response
As stated in the preamble (50 FR 1184), EPA concluded during the review
of the standard that 10 ppm reflects the level of performance that can be
consistently achieved by primary control devices on a continuous basis. For
this reason, the 10 ppm exhaust gas limit has been retained in the revised VC
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standard. In fact, however, emissions from primary control devices on a
short-term basis are often much less than 10 ppm. These lower short-term
emission levels would occur regardless of the level of the exhaust gas
standards. Thus, tightening of the exhaust gas s^anderds to 5 ocrr was
to be L'n'.'.arrantec' Because -;f ''Culc not s^or^ "icant: •' ^rrdct err ££-'.:•-• s •:
The concenter presented no evidence whrch would warrant a revis"'cr c~ ~
EPA's decision.
Comment Equipment and Work Practice r.ecuiremeras
what degree of control equipment "backup" is acceptable for complying with
the 10 ppm exhaust gas limits when the primary control equipment is down.
The commenter (IV-D-16) recommended that a provision be added to the standard
requiring a double level of redundancy for backup emission control equipment
used to meet the exhaust gas limits. The commenter further recommended that
backup incinerators be required to be maintained on "warm" standby and that
flares be approved as the second level of redundancy.
Response
Review of enforcement and compliance experience under the VC standard
found that most plants have installed some level of backup control equipment
to meet exhaust gas limits. For example, discussions with four EDC/VC
producers indicated a range of 15 to 100 percent excess incineration capacity
availability under normal operating conditions. The five EDC/VC plants
operated by these producers varied in the number of production units and in
their association with larger, multi-complex chemical plants. As was expected,
the number and configuration of backup incinerators was different for each
plant. In similar discussions with two PVC producers representing seven
plants, it was learned that in addition to incineration, solvent absorption
is being used for both primary and backup control of exhaust gases. Again
the number, type and configuration of backup control devices varied among the
different PVC plants (Docket Item IV-B-1).
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Because of the inherent differences in the plants and processes to which
exhaust gas control devices are applied, coupled with the variation in
effectiveness of operating these devices, it is impractical to specify the
exact amount of backup needed. Nonetheless, EPA agrees, in general, wit'1 ~':a
coir,me"ter' s sugcestiers O'i tre need for and cctra~icr, J': bc.c\-jc ;c.~::';~
devices. For example, backup control dev'ces are necessary to re:p tj-iiurs
control of VC emissions in exhaust gas during periods when the primary
control device is down. In the absence of a backup control device, nlan^s
might have to undergo costly shutdown of process equipment each time the
primary control device is Jown for scheduled o^ unschedincc ^a - i~~erz^r_~ '. ;_,
avoid violating the 10 ppm exhaust gas limits. Even wnen backup contro"
devices are available, exceedences of the 10 ppm exhaust gas limit are
possible. However, plants must analyze and identify ways of operating their
primary and backup control systems to improve the ability of the combined
systems to continuously control exhaust gas emissions. Thus, because it is
impractical to specify the degree of backup needed in the standard.
Comment Specification of 3-Hour Averaging Period in
Exhaust Gas Standards
Two commenters (IV-D-1, IV-D-4) recommended that the 3-hour averaging
period be specified in three sections of the regulation where 1C ppm limits
were not clarified by indicating a 3-hour averaging period.
Response
As explained in the preamble to the proposed revisions (50 FR 1192), the
exhaust gas standards should appropriately specify a 3-hour average to be
consistent with the performance test specifications for these emission
sources.
The three sections of the regulation pointed out by the commenters have
been revised as recommended.
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2.5.2 Oxychlorinatjon Vent Standard
Comment Withdrawal of Lower Oxychlorir.ation
Vent Standard
The comrnenter (IV-D-12) pointed out that the 1977 proposal would have
required new cxych Tori nation vents to meet an emission limit c4" 5 ppm based
on the use of oxygen as a feed material instead of air. The ccrrmenter stated
that EPA has failed to present any discussion which would justify the
withdrav/al of this proposal.
Response
In the preamble (50 FR 1185), EPA presented evidence supporting its
decision not to require more stringent control of new and existing oxychlori-
nation vents. First, the review of the standard identified no new control
technology applicable to oxychlorination vents that had been developed since
the original standard was established. Second, the cost to incinerate
existing oxychlorination vents was reevaluated, and the conclusion of the
original standard support study (Docket Item II-A-2) that incineration of
existing oxychlorination vents is not cost-effective was sustained in the new
analysis. Finally, with the possible exception of one plant, new EDC/VC
plants with oxychlorination reactors are not expected to be constructed.
However, if constructed, a new plant would be subject to the New Source
Performance Standards for air oxidation processes or to BACT or LAER require-
ments of new source review regulations. As a result of these regulations,
new oxychlorination vents would be controlled to a level consistent with the
1C ppm exhaust gas limits in the VC standard.
No information was provided by the commenter to change the EPA's decision
to retain the existing oxychlorination vent standard.
Comment Specification of 3-Hour Averaging Period
in Oxychlorination Reactor Standard
Two commenters (IV-D-1, IV-P-4) recommended that the 3-hour averaging
period be specified in the emission limit for oxychlorination reactors.
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Response
As explained In the preamble to the proposed revisions (50 FR 11S2), the
exhaust gas limits should appropriately specify a 3-hour average to be con-
sistent with the performance test specifications for these emission sources.
This is also true for the oxychlorination vent limit. The oxychlorination
reactor standard has been revised as recommended.
2.5.3 Residual Vinyl Chloride Standards for PVC Pesins
Comment Withdrawal of Lower Stripping Requirements
One commenter (IV-0-12) stated that EPA vrithdrew the proposed reduction
in the residual VC limits for new PVC resins because it was determined that
only some resins can now be stripped to these levels. The commenter asserted
that this conclusion is based on the assumption by EPA that an emission level
must be currently demonstrated to form the basis of the standard, but according
to the commenter, that demonstration is not required by Section 112. Further,
the commenter stated that the lower limits are currently being achieved by
many PVC production facilities and that many of the remaining facilities are
close to the limits. The commenter stated that the more stringent limits
could be achieved by new facilities, as well as by existing facilities if
given a three year lead time, by copying the equipment and procedures currently
used by the leading facilities.
Response
As discussed in the preamble (50 FR 1185), EPA rejected more stringent
stripping level requirements for new resins primarily because of the difficulty
in defining a "new" resin. Although resin compositions are adjusted routinely,
completely "new" resins are seldom if ever made.
The EPA further concluded that there is insufficient technology basis
for more stringent stripping requirements for all resins. In particular,
improved stripping technology is capable of lowering residual VC levels in
only some of the resins currently produced. The ability of improved stripping
technology to achieve lower residual VC levels depends on the resin type and
mix at a particular plant. The equipment and procedures that are effectively
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being used to strip a specific resin may be ineffective on another resin.
^any plants already use improved technology where applicable to average out
the stripping levels achieved for hard-to-strip resins. This technique of
averaging the stripping results o^ hard-to-strip resins with resins that are
more readily striked e^ows these darts tc comply with the ::i;-''e~t r^^'',:M~
VC standard wnile continuing to practice the hc.rd-to-5tr ip resir.s. Ire. easi ,.c
the stringency of the residual VC standard for all resins would, in the
opinion of EPA, force some plants to discontinue production c^ some resins
unreasonably. The commenter submitted no new information on that point.
2.5.4 Peactor Opening Loss Standard for In-Reactor-Str^ppers
Comment Compliance waiver Request
The commenter (IV-D-3) stated that the proposed calculation procedure
for determining reactor opening loss for reactors used as strippers mav
necessitate installation of more accurate instrumentation. He requested that
the regulation provide for waivers of compliance to allow time to select,
order and install additional instruments.
Response
The calculation procedure for determining reactor opening loss emissions
for reactors used as strippers provides plants that perform in-reactor
stripping an optional method for demonstrating compliance with the emission
limit for reactor openings. Plants using the calculation procedure will be
required to continue their current practice for demonstrating compliance
while selecting, ordering, and installing the instruments used to measure the
reactor conditions necessary for calculating reactor opening loss.
Comment Status of Previously Approved Methods
The commenter (IV-D-1) noted that the proposed emission testing
requirements for reactors used as strippers appear to require all stripping
operations with approved calculation methods to resubmit their calculation
methods for approval and questioned whether resubmittal of already approved
methods was intended.
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Response
The EPA developed a calculation procedure for determining reactor
opening loss emissions from reactors used as strippers to provide a uniform
method for use by all plants that perform in-reactor-stripping. However,
plants
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emission limits cannot be granted in place of an established emission limit,
but only alternative means of emission limitation.
2.6 MISCELLANEOUS COMMENTS
Comment Regulatory Flexibility Act - Small Business
Definition
The commenter (IV-D-3) stated that EPA incorrectly concluded that nc
small business (i.e., less than 500 employees) is affected by the proposal.
The commenter's subsidiary PVC company has 30C employees.
Response
In response to the comment there are three points that are important.
The first point is that at the time the economic analysis (Docket Item IV-B-11)
was performed the commenter's company did not exist.
The second point is that the Regulatory Flexibility Act (RFA) defines a
small business based upon the size of the total company including the parent
company plus all subsidiaries, rather than the size of individual subsidiaries
or individual plants. The commenter's assertion that it is a small business
referred only to the size of a subsidiary and not to the total company.
Later information provided in response to questions from EPA shows that the
total company is not a small business because it has more than 500 employees.
The third point is that size alone is not the only test in assessing the
need for a regulatory flexibility analysis. Significant economic effects
must also be likely, otherwise a regulatory flexibility analysis is not
required. The EPA does not expect such effects. Therefore, for the reasons
cited above, the regulatory flexibility discussion currently in the economic
analysis in the BID does not require any changes.
Comment Economic Impact of Standard
The commenter (IV-D-3) stated that costs required to comply with the VC
standard have a negative impact on the industry's profitability and competitive
situation in regard to foreign producers.
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Response
The ccmmenter discusses three subjects in its comment and its
supplementary information:
» the general economic condition of the domestic VCM/PVC industry
• the economic condition for the commenter's facility specifically
(but with only a limited amount of supporting financial infcnr.ation)
0 the foreign competition.
The economic analysis presently available (Docket Item IV-B-11} incHices
consideration of the above subjects (with the exception of information
specific to the ccmmenter's facility because it did net exist at n:he time;.
Consideration of the general economic condition of the domestic industry runs
throughout the analysis. Foreign competition is also specifically discussed
in Section 8.1.8. More than 2 years have passed since the economic analysis
was completed, so naturally changes have occurred in the industry during the
interim. However, the new information supplied by the commenter about the
industry in general and about foreign producers is not significantly different
from what is currently in the economic analysis. Overall, the economic
analysis appears to be reasonable in addressing the impact of the VC standard
on the VCM/PCV industry.
The financial information presented by the commenter concerning its
specific situation is insufficient to permit a detailed examination. Also,
because the firm is only about 1-1/2 years old, its young age sharply limits
the value of an analysis of historical financial performance. Two points
indicate that the current economic analysis is reasonable. The first point
is that, in general, the commenter's situation seems to be reasonably similar
to the model plant analysis presented in the economic analysis. For example,
a calculation of the cost increases per kilogram of capacity indicates that
the cost increases presented are approximately the same as those for the
model plants. The second point is that the owners and managers of the
commenter's facility are not newcomers to the industry. Therefore, because
the owners and managers had a high degree of prior knowledge about the
industry, considerable importance should be attached to the fact that they
elected to proceed and purchase the plants in question as recently as
July 1984.
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Comment VC Emissions from Landfills
The commenter (IV-D-10) agreed with the EPA's approach of requiring
plants that generate off-specification PVC resins to meet standards designed
to facilitate the ultimate disposer of the cf—specif ication resin in ccir.nlyinc
•,vi"?i tne envirorT.enta1 regu'aticns epp'iccive to hazarccus waste r'stoicT .
"The commenter expressed concern that stripping requirements for o~':-
specification PVC resins prior to removal to landfills may not be sufficient
to prevent subseat;ent exceedences of the proposed drinking ware** standarH -or
VC. The commenter explained that VC contamination of drinking water is
not required to be disposed in facilities regulated under Suoiit'e C or -r,e
Resource Conservation and Recovery Act (RCRA). The ccmmenter urged EPA to
better coordinate all regulatory activities pertaining to VC.
Response
This rulemaking is limited in scope to the regulation of atmospheric
emissions of VC from off-specification PVC resins in landfills. In this
context, the stripping requirements in the standard for off-specification PVC
resins are believed to be the most effective way of limiting VC emissions
from PVC resin in landfills. If there are other environmental consequences
of the disposal of off-specification PVC resins, appropriate restrictions can
be applied under other statutes.
Comment Offer to Assist RCPA Task Force
The commenter (IV-D-1/ offered to provide assistance to the Task Force
established under Subtitle P of RCRA in their assessment of emissions of VC
from hazardous waste facilities, municipal landfills and other air emission
sources. Further, he requested that his organization be kept informed on the
task force's activities.
Response
The commenters1 request has been forwarded to the RCRA Task Force.
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Comment
Reporting of Design Capacity
The commenter (IV-D-3) stated that the requirements in proposed 4C ChP.
6i.70(f) for plants to report design capacity information is inappropriate as
this information is proprietary. Further, plants that strip in the reactor
shcul
irrelevan^ for compliance deternrnation ana other plants shoulc oe allcv^c:
provide design capacity in a separate confidential document.
Response
design capacity o~~ a FVC plant in terms of an estimate of the number of
polymerization batches the plant is capable of producing, rather than specific
batch sizes or rates. Such information would not reveal significant informa-
tion on actual production and, consequently, would not ordinarily involve
confidentiality problems. However, if the owner or operator of an affected
facility has reason to believe that this or any other information submitted
to EPA should be treated as confidential, such treatment can be requested at
the time of submittal and a decision on the request can be made by EPA.
In the case of plants that strip in the reactor, no reporting of design
capacity data is required. For the added compliance method for in-reactor-
strippers, plants need only report VC emissions calculated to be in excess of
the combined limit for reactor opening loss and sources ^ollowing the stripper.
Information on design capacity needed for the calculation method need only be
retained at the plant in the records for compliance calculations.
Comment CERCLA Reporting Requirements
Three commenters (IV-D-1, IV-D-6, IV-D-14) requested clarification on
the applicability of the Comprehensive Environmental Response, Compensation
and Liability Act (CERCLA) reporting requirements to sources regulated under
the VC standard, specifying whether VC releases from EDC/VC and PVC plants
are required to be reported under CERCLA. Commenter IV-D-14 specifically
questioned whether emissions below the threshold concentration defining an
actionable leak are intended to be reported under CERCLA. A third commenter
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(IV-D-12) stated that relief valve discharges of VC are reportable under
CERCLA, except to the extent that they are the result cf a genuine emergency.
Response
Under the provisions cf CERCLA, releases of hazardous substances which
are federally permitted are not subject to CERCLA notification requiregents
and liabilities. The definition of "federally permitted release" in Section
101(10) or" CERCLA specifically includes ". . . (H) any emission into the air
subject to a permit or control regulation under . . . Section 112 ... of
the Clean Air Act ..." therefore, emissions in compliance with this star care
are not subject to CERCLA. However, emissions exceeding this standard and
the reportable quantity provisions of CERCLA are subject to both statutes.
Comment Reporting and Recordkeeping Requirements
Four commenters (IV-D-3, IV-D-8, IV-D-12, IV-D-13) addressed the proposed
reporting and recordkeeping requirements. The first commenter (IV-D-3)
disagreed with the EPA, estimates that the annual paperwork burden will be
reduced by 2.8 person years by the proposed revisions. The commenter claimed
that the inclusion of the Subpart V requirements would necessarily increase
the paperwork burden. The second commenter (IV-D-8) stated that the proposed
changes in reporting requirements represent an emphasis on emission reduction
rather than increasing paperwork. The third commenter (IV-D-12) stated that
all test results should be reported, not just those that exceed the standards.
Such a requirement would promote accuracy and completeness and permit EPA to
build a data base for future revisions of the standard.
Response
The reporting and recordkeeping burden resulting from the revised
standard was evaluated by EPA using standard Agency procedures to arrive at
the estimate that the burden would be reduced by 2.8 person-years. Basically,
this estimate reflects the reduction in reporting and recordkeeping require-
ments in the revised standard. The calculations on which this estimate is
based have been reviewed by OMB as a part of the Information Collection
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Request, which is available for inspection in the docket (Docket Item IV-F-1).
The ccmmenter has suggested re specific errors in this analysis nor recommended
an alternative analysis.
The submission of all test data associated with the standard has not
been required because such a requirement would imcose an urnecessar.
Burden
on both the respondent and EPA. It is mere productive to check "•nto the
accuracy and completeness of calculations as the need arises (using the
authority of Section 114) than to handle a quantity of routine reports. The
calculations are required to be maintained for a 3-year period. Further, an
adequate data base for future review of the standard can be obtcvreo v,ithout
such extensive commitment of resources to reporting.
Since proposal, EPA decided to retain 10-day reporting requirements for
relief valve discharges. In addition, quarterly reporting of excess emissions
will be required instead of semiannual reporting, as proposed. The net result
of the promulgated changes to reporting and recordkeeping requirements is not
expected to significantly increase or decrease the paperwork burden compared
to the existing standard.
Comment Typographical Errors
Five commenters (IV-D-1, IV-D-3, IV-D-6, IV-D-8, IV-D-9) pointed out
typographical errors in the Federal Register notice.
Response
The typographical errors have been noted and those contained in the
regulation will be corrected at promulgation.
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In response to the EPA's notice that the Agency did not intend to
promulgate the amendments to the VC standard \,bich we-e -rcocsed -;n 1CT"7, t?
Natural Resources Defense Council 'NRDC) and the Environmental Defense Fi:r.d
The NRCC/EOF petition was based on four main objections. F'rst, ^TC/^C1-
stated that the EPA's announcement that it did not intend to promulgate the
proposed amendments was a final administrative action, which was not preceded
by a notice proposing the withdrawal and allowing for public comment on the
action. Second, NRDC/EDF objected to the EPA's use of cost information in
the standards setting process, stating that the balancing of the costs and
benefits of VC emissions control is in conflict with the requirements of
Section 112 of the Clean Air Act. Third, NRDC/EDF objected to any interpre-
tation of Section 112 that establishes a requirement that a level of emission
control be "consistently achieved" in order to form the basis of a standard.
Finally, NRDC/EDF stated that the EPA's decisions on specific portions of the
proposed amendments were in conflict with the evidence before the Agency on
those issues.
The criteria established for granting such a petition for reconsideration
are: (1) the petition must be based on information which was not and could
not reasonably have been presented during the original rulemaking; and (2)
the petition must provide substantial support for the argument that the
challenged action should be changed. See Denial of Petition to Revise NSPS
for Stationary Gas Turbines, 45 FR 81653 (December 11, 1980). The objections
raised in the petition submitted by NRDC/EDF in this rulemaking do not meet
either criterion.
The first objection raised by NRDC/EDF, that there was inadequate
opportunity for public comment concerning the Agency's decision not to
3-1
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promulgate the proposed VC regulations, is not supported by the record of
this rulemaking. Between the proposal of the amendments to the VC standard
and the decision not to promulgate them, 8 years have elapsed. During this
time, the amendments, their potential consequences, and the alternative
communicated to NPHC and EDF prior to the "IAPCTAC meeting. In l"'gr:t c~ ^his
record, EPA does not believe that an additional public comment period would
be either necessary or helpful in the resolution cr these issues.
The second issue raised by NRPC/FPF in the petition for reconsideration
ccncGTrs^ "chs cof:2irlf::TdT"~!on c ^ ^ ^ s "t s o ^ ^ c n "" r o "I ^'n s^^^inp r ^ o <~ ' ^ ? r- ~ r r ~ -,~
is the EPA's judgment that the VC standard satisfies the requirement or"
Section 112 of the Clean Air Act that the standard be set at a level which
provides an "ample margin of safety" to the public. Further, EPA believes
that cost and feasibility may be considered in setting the standard. This
argument has been fully examined by the Agency, as discussed in the 1975-1976
VC rulemaking and discussed in the Agency's brief in NRDC v. EPA , Mo. 85-1150
(D.C. Cir). No additional information in support of their argument has been
put forward by NRDC/EDF.
The third issue raised by NRDC/EDF concerns whether an emission level
must be "consistently achieved" in order to form the basis of the standard.
This issue was raised with specific reference to the 10 ppmv standard for
exhaust gas VC emissions. This standard was selected because it was determined
that it provides the public v;it.h the ample margin of safety required by
Section 112. Although a lower emission limit might be assumed to increase
that margin, such a level has not been shown to be achievable on a long-term,
never-to-be-exceeded basis. No additional information has been submitted by
NRDC/EDF to refute the finding that the 10 ppmv emission limit for exhaust
gases provides the required margin of safety for the public.
Finally, the petition points to three actions made by the Agency in this
rulemaking which NRDC/EDF believe to be contrary to the evidence before the
Agency on those issues. These actions are: (1) the decision not to promulgate
the 5 ppmv standard for exhaust gases in favor of the existing 10 ppmv
standard; (2) the decision not to promulgate the 5 ppmv standard for
3-2
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oxychlorination vents; and (3) the decision not to lower the residual VC
limit for new dispersion resins from 2,OCG pprn to 500 ppm, or to lower the
limit for other resins from 400 ppm to 100 ppm. In each case, the petitioners
presented no nev; information in the petition ~or reconsideration relevant to
the decision to retain the existinn standards.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
1 REPORT MO 2.
EPA 450/3-86-00^
4 TITLE AND SUBTITLE
Vinyl chloride standard: Responses to Comments on
January 1985 Proposed Revisions
7 AUTHOR(S)
3 RECIPIENT'S ACCESSION NO
5 REPORT DATE
September 1986
6 PERFORMING ORGAMZAT'CN CODE
8. P E R F O R ,V1 ; N G O R G A \ i Z A T , C \ R £ = C P. T \ C
10"-J-V=- = V-
1 2 SPCMSCR VG AGE'NC • \A,ME A.ND A3Cn £33 13 ~ i P £ ;, F P, £ PC P "" A.\ D - £ - „ ; ; ; -L : i _
Office of Air and Radiation i
u.a. unvironineritai Protection Aaer.c" id SPCNSCP ^3 A-?\C- :::?
15 SUPPLEMENTARY ,\OT£S
16 ABSTRACT
This document summarizes and responds to comments on the proposed revisions
to the vinyl chloride standard set under Section 112 of the Clean Air Act.
17
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
J. COSATI Heidi Group
NESHAP
Hazardous Air Pollutants
Vinyl chloride
18 DISTRIBUTION STATEMEN1
Unlimited
19 SECURITY CLASS (This Report/
Unclassified
21 NO OF PAGES
~
SPA Form 2220-i 'Rev. 4-77)
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