October 10, 2012

MEMORANDUM

SUBJECT: Meeting notes for the October 9, 2012 Meeting with AF&PA & NCASI

FROM: John Bradfield

Kelley Spence

TO: Project files

This memorandum summarizes the meeting between the American Forest and Paper Association 

(AF&PA), National Council for Air and Stream Improvement (NCASI), member company 

representatives, and the U.S. Environmental Protection Agency (EPA) on October 9, 2012. This meeting 

was to discuss the venting allowances for noncondensible gases (NCGs) and the pending review of the 

kraft pulp mills new source performance standards (NSPS). The agenda for the meeting is provided in 

Attachment 1.

Meeting Attendees:

Corey Brandt-RockTenn Skip Missimer-PH Glatfelter

Ken Brockway-Green Bay Packaging Paul Noe-AF&PA

Mike Curtis-Georgia-Pacific John Petchul-Greif Packaging

Russ Frye-Counsel for AF&PA Annabeth Reitter-NewPage

Rich Garber-Boise Inc. Jeff Shumaker-International Paper

Ed Harrington-MeadWestvaco Jim Taylor-MeadWestvaco

Tim Hunt-AF&PA

Ashok Jain-NCASI

Vipin Varma-NCASI

John Bradfield-EPA/SPPD

Kelley Spence-EPA/SPPD

Nick Swanson-EPA/SPPD

Katie Hanks-RTI

Tom Holloway-RTI
Discussion Points:

• Discussions during the meeting primarily followed the industry handouts in Attachments 2 through 4 

regarding NCG venting duration from the NCASI NCG venting survey, key takeaways from the NCG 

venting survey, and an alternate long-term treatment standard for hazardous air pollutants (HAPs) in 

low-volume high-concentration (LVHC) and high-volume low-concentration (HVLC) NCGs.

• In addition, AF&PA noted concern about statements in the preamble to the subpart S risk and 

technology review (RTR) rule and response-to-comments document that emissions during periods of 

startup, shutdown, and malfunction (SSM) are the same as emissions during normal operations.

AF&PA indicated that this statement is incorrect, citing information previously provided to EPA, and 

suggested that EPA formally clarify its statement. AF&PA indicated they are currently evaluating 

their options concerning EPA’s removal of the SSM exemptions and supporting rationale.

• Discussions about the pending NSPS review included the information sources being used in the 

review and the data needed for the economic impacts analysis to determine which sources would 

modify, reconstruct, or be replaced during the 5-year period after proposal of the NSPS review.

AF&PA noted that they will be submitting comments on the proposed consent decree for the NSPS 

review.

• There was insufficient time during the meeting to discuss the final two items on the agenda (i.e., 

subpart MM RTR and volatile organic compound [VOC] measurement), which could be addressed in 

a later meeting.

• Action items following the October 9 meeting include the following:

o NCASI to elaborate on the development of the alternate standards for LVHC/HVLC 

treatment.

o EPA to review the alternate standards and relay any questions/comments.

o Industry to develop and provide a suggested alternate standard for treatment of stripper 

off-gases (SOGs).

o EPA to relay AF&PA’s concern regarding statements that emissions during SSM are the 

same as emissions during normal operation and its suggestion for a formal clarification.

o EPA to set up a follow-up meeting with industry in December (date TBD) to discuss the 

initial findings of the NSPS review.
Attachment 1

Draft Agenda for AF&PA-EPA Meeting on Venting Allowances and SSM
Draft Agenda for AF&PA-EPA Meeting on Venting Allowances and SSM

EPA Offices in RTP: Room C113

October 9 meeting from 1:30 to 4:30 PM

Conference phone: 919.541.4557

EPA: John Bradfield, Bill Schrock, Kelley Spence, Nicholas Swanson, Robin Dunkins

AF&PA: Vipin Varma, Ashok Jain, Tim Hunt, Jeff Shumaker, Rich Garber, Mike Curtis, 

Guy Martin, Corey Brandt, Skip Missimer, Ed Harrington; others may join by phone

• Introductions and Goals of Meeting

• Review NCASI survey results on SSM and Venting

o Answer questions about distribution of responses and any outliers

o Review duration/frequency summary for venting and SSM events

• Discuss June 27 AF&PA/NCASI comments

o Review main causes for events

o Answer questions about information presented

o Clarify statements in preamble, response to comment and background 

document that emissions during SSM are same as normal operations

• Explore alternatives to current venting allowances

o Review considerations important to EPA

o Review considerations important to industry

o Discuss approach that would integrate 98% control efficiency with 1 and 

4% venting periods

o Discuss issues with steam stripper 10% allowance and possible work 

practices such as use of wastewater treatment systems

• Discuss Kraft NSPS review

o What data is EPA using to complete its assessment?

o What economic analysis is EPA planning?

o Comments on consent decree schedule due by 10/15

• Subpart MM RTR

o EPA discuss any plans or issues at this stage

 Identification of any “technology changes” being examined

 Economic considerations – value of averaging and NDCE-DCEs

subcategories/distinctions

• VOC measurement (if time)

o Review NCASI test method studies (TB 991) and April EPA-NCASI Mtg

o Confirm that EPA comfortable with Method OTM 26 as the best predictor

o Research continuing slowly on other wood species but paper sources 

deferred given other regulatory priorities
Attachment 2

Venting Duration Summaries from the NCASI NCG Venting Survey
VENTING DURATION SUMMARIES FROM THE NCASI NCG VENTING SURVEY

Background

The NCASI NCG venting survey was conducted in response to specific questions, raised

by the EPA in the December 27, 2011 proposal, on intermittent NCG venting that occurs during

routine operations and covered under the venting allowances.  This survey was developed and

conducted in order to highlight the basic principles that apply in designing and operating these

systems, while keeping in mind that each individual NCG system is unique in the types of

sources it collects, its configuration, and its accommodation of site‐specific constraints.  

Facilities were requested to provide qualitative information, based on prevailing process

knowledge and experience, on the types of events triggering intermittent venting episodes.  

Additionally, facilities were also requested to identify operating conditions or threshold

operating parameters used to differentiate Startup Shutdown and Malfunction (SSM) venting

events from those occurring during routine operation.  A total of 81 mills responded to the

survey.  The results of the NCG Venting survey were summarized for the EPA in a summary

report on June 27, 20121

.  The summary report analyzes survey responses and draws collective

conclusions on the types of events triggering intermittent venting.

Questions 9 through 12 of the NCG venting survey2 requested facilities to provide

information on the duration of venting episodes associated with both SSM3 and non‐SSM4

events.  Facilities were requested to provide venting duration information, either for 2011 (two

semi‐annual reporting periods) or for an alternative reporting year.  These data were collected

primarily to obtain a snapshot of industry performance as compared against the 1% and 4%

allowances.  An analysis of longer‐term venting performance (either on a mill‐specific or

industry‐wide basis) was beyond the scope of the survey.  This one‐year snapshot on venting

performance was collected with the understanding that individual mill performance data would

not be disclosed to other industry respondents or identified as such.

The Tables provided below summarize the venting duration data collected from 81 mills

responding to the survey.  This summary includes all venting episodes (both SSM and routine

events) and reflects the regulatory requirements currently in place with the removal of the SSM

exemption in the September 11, 2012 rulemaking.  It is worthwhile to reiterate that these data

are a snapshot of performance and not necessarily indicative of long term performance.  

However, it serves to highlight the importance of preserving these venting allowances and that

the current levels of these allowances (1% and 4%) are appropriate as indicated by industry

averages.

                                                           

1 NCASI, “The Collection and Transport of Noncondensible Gases (NCG) in NCG Systems at Pulp and Paper Mills:

Background and Characteristics of NCG Systems and Summary of NCASI Survey Responses,” June 27, 2012. 2 Survey questionnaire provided as part of the June 27, 2012 submittal. 3 Venting associated with SSM periods. 4 Venting that occurs during routine operations and not associated with SSM conditions and reported under the 1%

and 4% excess emissions allowances in the 1998 subpart S MACT standards
LVHC and HVLC Venting Duration Summaries for one reporting year (all venting including SSM

Periods)

As summarized in the Tables below, the maximum LVHC venting duration inclusive of

those corresponding to SSM periods was ~ 1.9%.  In the case of HVLC systems, the maximum

venting duration inclusive of SSM was ~ 9.9%.   

 A handful (2 or 3) of facilities would have exceeded the 1% venting allowance for LVHC

and 4% venting allowance for HVLC during that reporting year if they had been required

to include venting events associated with SSM periods.

 NCG venting performance at these mills during this particular reporting year also

included a few anomalous events not reflective of year‐on‐year performance.

 The 95th percentile of venting performance for LVHC and HVLC systems in 2011 (and in a

few cases 2010) when including SSM periods was 0.85% and 3.51% respectively and fall

within the currently applicable emission allowances.

 The 95th percentile of venting performance when including SSM periods suggests that

the current levels of allowances (1% and 4% for LVHC and HVLC systems) are

appropriate and justified.

LVHC Venting

(Including SSM

Periods)

   First semi‐annual Period    Second semi‐annual

Period

   Annual **

     Minutes   % of

Operating

Time

Minutes   % of

Operating

Time

Minutes   % of

Operating

Time

Maximum    3816 1.47% 4940 1.91% 8756 1.67%

Average    563 0.22% 530 0.20% 1301 0.25%

               

95th percentile    2214 0.85% 1462 0.56% 3857 0.73%

                     

HVLC Venting

(Including SSM

Periods)

   First semi‐annual Period    Second semi‐annual

Period

   Annual **

     Minutes   % of

Operating

Time

Minutes   % of

Operating

Time

Minutes   % of

Operating

Time

Max    17372 6.70% 25600 9.88% 37600 7.15%

Average    1881 0.73% 2055 0.79% 3911 0.74%

                     

95th percentile    8000 3.09% 9092 3.51% 13386 2.55%

** “Annual” grouping created to include mills providing annual venting data in the survey.   

Grouping includes all 81 responding mills.
Attachment 3

Key Takeaways from Non-Condensible Gas (NCG) Venting Survey
KEY TAKEAWAYS FROM NON‐CONDENS

GAS (NCG) VENTING VENTING SURVEY

Industry	Group	Meeting	with	OAQPSOctober 9 2012 October 9,	2012
NCASI Venting Survey

Survey

• A	total	of	81	mills	respq y onded	to	qualitative	survey

• Highlights	basic	principles	involved	in	designing	and	opera

systems	

• Survey designed to gather information on types of events tr

Survey designed to gather information on types of events tr

venting	episodes	

• Survey	designed	with	the	complexity	and	uniqueness	of	ind

NCG system NCG system in mind in mind –

• Unique	in	the	types	of	sources	collected,	the	configuration,	and

accommodation	of	site‐specific	constraints		

• Facilities requested Facilities requested to provide qualitative to provide qualitative information information base

base

prevailing	process	knowledge	and	operating	experience

• Facilities	requested	to	also	identify	operating	conditions	or

operating parameters used to differentiate Startup operating parameters used to differentiate Startup / Shutd

hutd

venting	events	from	those	occurring	during	routine	operati
NCG Collection / Transport Design Philosop

NCG Collection / Transport – Design Philosop• Exp py losions	in	collection	and	transport	systems	are	

by	the	coexistence	of	three	primary	ingredients,	viz

• combustibles	within	flammable	ranges,	• sufficient oxygen and oxygen,	and• an	ignition	source.		

• The	strategy	adopted	for	design	and	operation	of	th

systems	is	to	prevent	explosions	by	excluding	one	othe above the above‐mentioned components from these syste

mentioned components from these syste

times.
NCG Collection / Transport Design Philosop

NCG Collection / Transport – Design Philosop• LVHC	and	SOG	Systems

• Maintain	concentrations	above	Upper	Explosive	Limits	(UE

major	components

• Prevent ingression of air (use steam ejectors for transport) Prevent ingression of air (use steam ejectors for transport)• Eliminate	condensation	and	two‐phase	flows	(due	to	turpe

• HVLC	Systems

• Eliminate	explosion	hazard	by	ensuring	that	combustibles	

concentrations	well	below	Lower	Explosive	Limits	(LEL)

• Eliminate	turpentine	carryover	(potential	to	exist	in	chip	b

gases)
NCG Transport Approaches• Two	alternatives	available,	viz.,	vapor	phase	transfeNCG Transport ‐ Approaches

, ,p p 

and	conditioned	gas	transfer	system

• Vapor	phase	transfer	– heavily	insulated	and	heat	traced	us

thus preventing thus preventing the accumulation of condensible compone

the accumulation of condensible compone

methanol	and	turpentine

• Conditioned	gas	transfer	– reduce	water	vapor	and	conden

components being incinerated components being incinerated.		Includes the Includes the following addi

following addi

components.

• Gas	cooler/Condenser• Mist eliminator Mist eliminator• Indirect	steam	pre‐heater	to	re‐heat	gases
Key Takeaways

Four	most	identified	events	during / 	routine	/	normal	operation	that	trigger	intermittent	venting• #	1	‐ Primary	combustion	device	not	available

• Momentary	loss	of	NCG	burning	permissives• Not	caused	by	malfunctions	of	associated	equipment	and	a

the	ability	of	the	control	device	to	burn	NCGs.	

• An	example	‐ Transient	changes	in	process	steam/energy	d

the	mill	(inherent	variability	in	upstream	processes	or	swinproduction	rates)	cause	variations	in	steam	header	pressurcould	lead	to	changes	in	fuel	feed	rates	and/or	fuel	mixes	aburning	permissives.
Key Takeaways

Four	most	identified	events	that	occur	during	routine	/	nooperation	and	trigger	intermittent	venting• #	2	– Pressure	/	Temperature	interlocks	in	transport	sy

• Flow	balancing	between	different	branches	of	the	system• Interlocks	used	to	detect	flame	blow‐backs,	carry‐over	of	liquo

condenser/cooler	overload,	etc.

• #	3	– Process	Equipment	Outside	Normal	Operating	Ran

• Interlocks	at	or	near	process	equipment	are	designed	to	effect

any	variability	and	preventing	it	from	propagating	into	the	trasystem.

• Isolating process vessels Isolating process vessels during temporary periods of process during temporary periods of process 

allows	problem	isolation	and	continued	operation	of	the	NCG	

• This	ability	to	prevent	the	propagation	of	isolated	process	var

averts	the	onset	of	dangerous	and	py p otentially	catastrophic	con

the	NCG	system
Key Takeaways

Four	most	identified	events	that	occur	during	routinnormal	operation	and	trigger	intermittent	venting• #	4	‐ Switching	between	Incineration	Points

• Driver is primarily Driver is primarily safety and system safety and system integrity integrity• Transfers	of	LVHC	gases	from	primary	to	secondary	inciner

devices	are	required	to	be	preceded	by	steam	purges	to	rementrained air

• Steam	purge	requirement	is	frequently	a	permissive	built	in

control	logic
Key Takeaways – NCG Venting during Ro

y y g g

Operations• Inherent	p y rocess	variability	during p 	routine	operatio

cannot	be	reasonably	prevented	through	corrective

• Not	considered	to	be	malfunctions	of	equipment,	pr

or	cont ld i ro ev ces.

• Venting	episodes	are	designed	to	promote	safety	an

integrity integrity – they are inherent in they are inherent in “fail‐safe” control st

control st

• Insurability	of	NCG	systems	contingent	on	the	availability	o

systems

• Venting Venting events necessary necessary both for both for technological technological,	

operational,	and	safety	reasons
Startup and Shutdown (SS) Events Triggering 

Startup and Shutdown (SS) Events Triggering 

• Isolated	venting p qp 	of	process	equipment	before	reac

steady	state

• Inability	to	resolve	interlocks	due	to	process	varia

during startup and during startup and shutdown shutdown

• Intermittent	venting	of	isolated	sections	of	transp

system	due	to	flow	balancing	issues	

• Hi h th l i bilit Higher	than	normal	variability	i fl f n	 ows	from	sub t ‐sys ems

• Purge	requirement	of	concentrated	NCG	line	befor

mill	start‐up

• Transient	venting	of	LVHC	and	HVLC	sources	due	t

"warm	up"	of	boiler	

• Lower	than	normal	steam	requirements
Startup and Shutdown (SS) Events Contd

Startup and Shutdown (SS) Events – Contd.• While	the	venting p 	e isode	is	no	different	from	a	ven

episode	that	occurs	during	routine	or	normal	operatriggering	conditions	are	unique	SS	conditions

• Majority of the facilities use threshold parameters to differ

of the facilities use threshold parameters to differ

normal	operating	periods	from	SS	periods

• Twelve	of	the	81	facilities	reported	using	a	pre‐defined	set	

actions to differentiate SS to differentiate SS conditions conditions from routine operatio

from routine operatio
Other Elements ofthe Survey

Other Elements ofthe Survey• Venting p 	duration	summaries	provided	for	one	calen

reporting	year

• Intent	was	to	provide	a	snapshot	and	not	to	assess	long‐ter

performance

• Work	practices	during	steam	stripper	downtimes

• Majority	of	facilities	route	condensates	to	biological	treatm

systems	and	achieve	high	HAP	treatment	efficiencies

• Not	a	“zero	HAP	control”	scenario

• Information	on	state‐sp g p

ecific	recording	and	reporti

requirements	pertaining	to	NCG	venting	events	com
Questi
Attachment 4

Alternate Long Term Treatment Standard for HAPs in LVHC and HVLC NCGs
ALTERNATE LONG TERM TREATMENT STANDARD FOR HAPs IN LVHC AND HVLC NCGs

1.0 BACKGROUND

§63.443 of the Subpart S NESHAP standards, promulgated in April 1998, require the collection

and treatment of non‐condensible gases (NCGs) from specified equipment systems.  Low Volume High

Concentration (LVHC) and High Volume Low Concentration (HVLC) gases from applicable equipment

systems are required to be collected and transported to a control device that achieves one of the

following:  

1) Reduce total HAP emissions by 98% or more by weight; or

2) Reduce total HAP concentration at the outlet of the thermal oxidizer to 20 parts per

million or less by volume, corrected to 10% oxygen on a dry basis; or  

3) Reduce total HAP emissions using a thermal oxidizer designed and operated at a

minimum temperature of 1600 °F and a minimum residence time of 0.75 seconds; or

4) Reduce total HAP emissions using a boiler, lime kiln, or recovery furnace by introducing

the HAP emission stream with the primary fuel or into the flame zone.   

As promulgated in April 1998, periods of excess emissions reported under § 63.455 are not

violations of the requirements under § 63.443 (c) and (d) provided that the time of excess emissions

(excluding periods of startup, shutdown, or malfunction (SSM)) divided by the total process operating

time, in a semi‐annual reporting period, did not exceed 1% for LVHC systems, 4% for HVLC systems, and

4% for combined LVHC/HVLC systems.

With the September 11, 2012 rulemaking that finalizes the residual risk and technology review

(RTR) for Subpart S sources, EPA removed the SSM exemption for affected facilities and eliminated all

parenthetical language in the rule that applies to SSM periods.  Additionally, the EPA is also deferring

final action on whether to remove or modify the excess emissions provisions, pending review of more

recent information on the allowances that we have obtained from industry.  EPA expects to publish a

proposed rule describing any changes to the excess emissions allowance provisions, thus providing an

opportunity for public comment before taking final action.

2.0 SUMMARY OF NCASI SURVEY ON INTERMITTENT NCG VENTING

The NCG Venting survey conducted by NCASI, the results of which were summarized for the EPA

in the June 27, 2012 submittal1

, indicated that intermittent venting can be caused by events that occur

during normal operation including temporary control device non‐availability, steam‐purge requirements

when switching LVHC gases between control devices, and the occasional tripping of pressure/

temperature/flow interlocks.  The vast majority of these events are triggered by inherent process

variability and transient conditions in the collection, transport, and conditioning equipment.  

Additionally, survey responses indicated that intermittent NCG venting can also be caused by Startup

and Shutdown (SS) events.  As it pertains to the NCG system, SS conditions are unlike normal operation,

potentially create unique operating conditions, and trigger intermittent venting episodes.  As discussed

in the June 27, 2012 summary report, control system interlocks are an integral part of NCG system

                                                           

1 NCASI, “The Collection and Transport of Noncondensible Gases (NCG) in NCG Systems at Pulp and Paper Mills:

Background and Characteristics of NCG Systems and Summary of NCASI Survey Responses,” June 27, 2012.
design and operation.  They are designed to prevent unsafe operating conditions that could promote

ignitability such as two‐phase flows, gases in flammable ranges, and the ingression of air in LVHC

systems.  These control systems protect the structural integrity of the system and are essential to

prevent catastrophic operating conditions like explosions.  As discussed in the June 27, 2012 submittal,

these control systems and associated interlocks are prerequisites for the insurability of NCG collection

and transport systems.  The ability to vent these gases when unsafe conditions exist is therefore an

essential requirement for operating these collection and transport systems.

3.0 ALTERNATE TREATMENT STANDARD FOR NCG SYSTEMS OVER SIX‐MONTH AVERAGING

PERIOD

The methodology outlined below calculates an alternate numerical treatment standard,

applicable to NCG systems over a six‐month averaging period, and expressed as the minimum percent

destruction of HAPs in vent gases.  Facilities can use this approach (along with recorded information on

total venting periods and hours of operation) to demonstrate compliance with this numerical standard.  

The calculations are illustrated below:  

3.1 Basis and Assumptions for Calculations

1. Uncontrolled LVHC and HVLC HAP emission rates of C lb/hr and D lb/hr, respectively

2. Maximum operating hours in 6 month period   = (182.5 days) x 24 hours/day = 4380 hours

3. HAP treatment efficiency achieved by thermal destruction   = 98%

Treatment Efficiency of HAPs by Thermal Destruction

The destruction of NCGs in thermal oxidizers, boilers, lime kilns, and recovery furnaces results in

the near complete destruction of HAPs given the robust combustion conditions prevalent in these

devices.  As discussed earlier, facilities are provided with four alternatives to demonstrate compliance

with the treatment requirements under §63.443 (c) and (d), one of which is to demonstrate a

destruction efficiency of 98% or more by weight.  These four alternatives were considered to be

equivalent in their HAP treatment effectiveness during the development of the Subpart S NESHAP

standards.    

For purposes of calculating the long‐term numerical treatment standard, this analysis considers

all ongoing compliance, regardless of the alternative chosen, to be at the 98% destruction efficiency

level.  Therefore, this calculation methodology does not account for demonstrated destruction

efficiencies > 98%.  The 98% treatment efficiency used in this calculation is representative of a facility

demonstrating compliance with the applicable standard – a numerical value representing the minimum

expected destruction efficiency.
All venting episodes calculated at the total mass emission rate

For purposes of calculating the long‐term numerical treatment standard, this analysis assumes

that each venting episode results in emissions of C lb/hr or D lb/hr emissions (LVHC and HVLC systems,

respectively), i.e., sub‐system vents are also calculated at the total mass emission rate.  In reality, the

vast majority of NCG venting occurs from sub‐systems, in response to local control system interlocks.  

Sub‐system vents prevent potential problems from propagating further into the system and ultimately

causing a full‐system vent.  

3.2 Overall HAP treatment efficiency for LVHC systems over six‐month averaging period

Maximum potential HAP emissions in the 6 month period = C lb/hr x (4380 hours)   = 4380 C lb  

HAP Emissions at 98% treatment efficiency   = 4380 C x (1 ‐ 0.98)       = 87.6 C lb

HAP emissions due to LVHC venting up to 1% of the time   = (4380 hours) x (C lb/hr) x 0.01

= 43.8 C lb

Therefore, total HAP emissions during 6 month period = (87.6 C + 43.8 C)     = 131.4 C lb

Therefore, HAP treatment standard for LVHC System over 6‐month averaging period  

= (1 – 131.4 C/4380 C) = 97%

3.3 Overall HAP treatment efficiency for HVLC Systems over six‐month averaging period

Maximum potential HAP emissions in the 6 month period = D lb/hr x (4380 hours) = 4380 D lb  

HAP Emissions at 98% removal efficiency = 4380 D x (1‐ 0.98)       = 87.6 D lb

HAP emissions due to HVLC venting up to 4% of the time   = (4380 hours) x (D lb/hr) x 0.04  

= 175.2 D lb

Therefore, total HAP emissions during 6 month period = (87.6 D + 175.2 D) = 262.8 D lb

Therefore, HAP treatment standard for HVLC System over 6‐month averaging period  

= (1 – 262.8 D/4380 D) = 94%

   
3.4 Demonstrating compliance with the long term treatment efficiency standard

Example Operating Scenario ‐ LVHC System (Uncontrolled Emissions of C lb/hr)

Actual operating hours in the 6‐month period     = H hours (e.g., 4200 hours)

Actual LVHC or HVLC venting time in 6 month period    =   T hours

Maximum potential HAP emissions in the 6 month period = H hours x C lb/hr   = HC lb

Operating hours with 98% destruction         =   (H – T) hours

When all venting episodes, including sub‐system vents, are treated like a full‐system vent, the emission

rate (C lb/hr) is fixed.   

HAP emissions at 98% efficiency during 6‐month period

       = (H‐T) x 0.02 x C lb/hr

HAP emissions during T hours of venting  = (T hours) x C lb/hr   

Total HAP emissions during 6‐month period = ((H – T) x 0.02 +T) hours x (C lb/hr)

       = (0.02H + 0.98T)C lb

To demonstrate compliance, the following would apply

      [1 – (0.02H + 0.98T)/H] > 0.97 for LVHC Systems

      [1 – (0.02H + 0.98T)/H] > 0.94 for HVLC Systems