U.S. Environmental Protection Agency

Applicability Determination Index

Control Number: M990012 

Category: MACT 

EPA Office: Region 9 

Date: 09/30/1999 

Title: Control Devices and Venting 

Recipient: Wayne Morgan 

Author: Duane James 

Subparts: Part 63, S, Pulp and Paper Production 

References: 63.2 

63.6(e)(3)(A) 

Abstract: 

Q: Does venting apply to the individual sources at each step of the process or only to 

venting from the total closed-vent system? 

A: Venting applies to the total closed-vent system. Thus, venting is allowed only from the 

system as a whole, and not from individual sources. 

Q: If the control device is operative and problems occur in the closed-vent collection 

system, does this time count against the 4% allowance or is this a violation of the 

NESHAP? 

A: Whether the time counts against the 4% allowance or is a violation of the NESHAP 

depends on the Startup, Shutdown and Malfunction (SSM) plan. Problems that are 

avoidable through proper operation and maintenance, including bypasses that are not 

addressed in the SSM plan, would be violations. 

Q: Must the control device (Recovery Furnace) be inoperative (non-functional) in order for 

HVLC gas streams to legitimately bypass the control system? 

A: Yes. The control device must by inoperative/nonfunctional for the HVLC gas streams to 
bypass the control. 

Q: Is a pressure/vacuum valve on a liquor storage tank that vents to the atmosphere 

considered a leak or defect in the ductwork, piping or enclosure and therefore subject to the 

5/15 day time limit for repair or correction once detected? 

A: The 5/15 day schedule applies upon detection of a leaking or broken seal. However, 

uncontrolled venting from an affected source detected after the compliance date and not 

accounted for in the Title V permit constitutes a violation not covered by the enclosure leak 

or defect provisions. 

Q: Is a storage tank that vents through its pressure/vacuum valve for a 30 day period as a 

result of an incident other than a startup considered a malfunction or is it instead a 

NESHAP violation? 

A: A venting resulting from an incident other than a startup is predictable and does not fit 

the definition of malfunction. Thus, it is a violation of the NESHAP. 

Letter: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION IX

75 Hawthorne Street

San Francisco, CA 94105

September 30, 1999

Wayne Morgan

Air Pollution Control Officer

North Coast Unified Air Quality Management District 2300 Myrtle Avenue Eureka, CA 

95501 

Re: Clarification of NESHAP for Pulp and Paper Mills 

Dear Mr. Morgan,

This letter is in response to your June 15, 1999 letter addressed to Stephen Shedd of EPA's 

Emissions Standards Division which sought assistance in interpreting the provisions of the 

National Emissions Standards for Hazardous Air Pollutants (NESHAPs) for Pulp and Paper 

Mills (40 CFR part 63, subpart S) as they apply to a Louisiana-Pacific (LP) kraft pulp mill in 

your District. Your letter was forwarded to EPA's Region IX Office for resolution. We hope 

the information provided below will help the District resolve any issues that may be 

hampering the District's efforts to process the LP pulp mill's Title V permit and will clarify the 

intent of EPA's Office of Air Quality Planning and Standards when it issued this regulation 
and defined Maximum Achievable Control Technology for this source category. 

Since the LP mill was required to install equipment to capture and incinerate High Volume 

Low Concentration (HVLC) gas streams, we will assume that the mill is a new kraft mill 

which must meet the NESHAPs requirements for new sources. Furthermore, we will 

assume that the mill's liquor storage tanks are for weak black liquor. The NESHAP does not 

require control of strong black liquor storage tanks because most hazardous air pollutants 

are considered to have been removed from strong black liquor by other controls. 

Question 1: Does venting apply to the individual sources at each step of the process or only 

to venting from the total closed vent system? 

The NESHAP does not establish excess emission times for condensate collection. Excess 

emission times apply to control devices into which the closed collection system vents. 

Venting is allowed only from the total closed vent system, not the individual sources. 

Question 2a: If the control device is operative and problems occur in the closed-vent 

collection system (i.e., air-preheater to recovery is plugged), dictating a by-pass to the main 

stack, does the time involved in this example count against the 4% allowance or is this a 

violation of the NESHAP? 

Whether the time involved in your example counts against the 4% allowance or is a 

violation of the NESHAP depends on what has been defined as a malfunction under the 

Startup, Shutdown and Malfunction (SSM) plan. Problems that should be avoided through 

proper operation and maintenance, including bypasses that are not addressed in the SSM 

plan, would be violations of the NESHAP. Note that malfunction as defined in 40 CFR Sec. 

63.2 is "any sudden, infrequent and not reasonably preventable failure." "Failures that are 

caused in part by poor maintenance or careless operation are not malfunctions." 

Question 2b: Must the control device (Recovery Furnace) be inoperative (nonfunctional) in 

order for HVLC gas streams to legitimately bypass the control system? 

Yes, the control device must by inoperative/nonfunctional for the HVLC gas streams to 

bypass the control system. Per 40 CFR Sec. 63.6(e)(3)(A), facilities are still obliged under 

their SSM plans to make a good faith effort to control emissions and to operate "in a 

manner consistent with good air pollution control practices for minimizing emissions at least 

to the levels required by all relevant standards." 

Question 3: Does EPA interpret, under the NESHAP, pressure/vacuum valves on liquor 

storage tanks that vent to the atmosphere as a leak or defect in the ductwork, piping or 

enclosure which is subject to the 5/15 days for repairing and correcting it once detected? 

Once a facility and the delegated agency have determined which sources will be controlled, 

the facility should have a clear understanding of where the emission points are in each 

system. Vents should be controlled as part of the facility's compliance strategy. The 5/15 

day schedule would apply to a leaking seal, one that is broken. However, uncontrolled 
venting from an affected source that is detected after the compliance date and that is not 

accounted for in the Title V permit would constitute a violation and not fit the enclosure leak 

or defect provisions. 

Question 4: If a storage tank were to vent through its pressure/vacuum valve for a 30 day 

period (constantly on some days and intermittently on other days) and is not a result of 

startup or shutdown, would you consider these to qualify as a malfunction or should it be 

considered as a violation of the NESHAP? 

The District should refer to the definition of malfunction contained in 40 CFR Sec. 63.2. It 

appears as though the venting, as described above, is predictable and would not fit the 

definition of malfunction. This should be considered a violation of the NESHAP. 

We hope this letter throughly addressed your concerns. If you have additional questions 

regarding the Pulp and Paper NESHAP or require further clarification, please contact 

Yvonne Fong of EPA's Region IX Office at (415) 744-1199. 

Sincerely,

Duane James

Acting Chief, Enforcement 

Office