1 

Technical Support Document 

March 2015 

Regulations to Control Volatile Organic Compound Emissions from Degassing of Storage 

Tanks, Transport Vessels and Marine Vessels in the Houston/Galveston/Brazoria (HGB), 

Beaumont Port Arthur (BPA), Dallas-Ft. Worth (DFW) and El Paso Areas. 

EPA-R06-OAR-2011-0079 

Background 

On July 18, 1997, the Environmental Protection Agency (EPA) promulgated an 8-hour ozone 

national ambient air quality standard (NAAQS), known as the 1997 ozone standard of 0.08 parts 

per million (ppm), which was more protective than the previous 1-hour ozone standard (62 FR 

38855). On April 30, 2004, EPA published designations and classifications for the 1997 8-hour 

ozone standard (69 FR 23858). The HGB area, which consists of Brazoria, Chambers, Fort Bend, 

Galveston, Harris, Liberty, Montgomery and Waller counties was classified as a moderate ozone 

nonattainment area, with an attainment date no later than June 15, 2010. On October 1, 2008, at 

the request of the Governor of Texas, we reclassified the area as a severe ozone nonattainment 

area with an attainment date no later than June 15, 2019 (73 FR 56983). 

On March 27, 2008 (73 FR 16436), the EPA promulgated a revised 8-hour ozone NAAQS of 

0.075 ppm, known as the 2008 ozone standard. On April 30, 2012, the EPA promulgated 

designations under the 2008 ozone standard (77 FR 30088) and in that action, the EPA 

designated 10 counties in the DFW area as a Moderate ozone nonattainment area: Collin, Dallas, 

Denton, Ellis, Johnson, Kaufman, Parker, Rockwall, Tarrant, and Wise. Also in the action at 77 

FR 30088, the EPA designated the HGB area as a Marginal ozone nonattainment area. 

Volatile organic compounds (VOC) and oxides of nitrogen (NOx) are known as “ozone 

precursors”, as they react with oxygen and sunlight to form ozone. Motor vehicle exhaust and 

industrial emissions, gasoline vapors and chemical solvents emit NOx and VOCs. Controlling 

sources of NOx and VOC emissions can lower ozone levels in the ambient air. 

Sections 172(c)(1) and 182 of the Clean Air Act (CAA) require ozone nonattainment areas that 

are classified as moderate or above for ozone nonattainment to adopt Reasonably Available 

Control Technology (RACT) requirements for sources that are subject to Control Techniques 

Guidelines (CTGs) issued by EPA and for “major sources” of volatile organic compounds 

(VOCs) and nitrogen oxides (NOx). RACT is defined as the lowest emissions limitation that a 

particular source is capable of meeting by the application of control technology that is reasonably 

available considering technological and economic feasibility (44 FR 53762; September 17, 

1979). The Act also requires states to establish Rate of Progress (RoP) plans to ensure the 

capacity of a state to meet emission reduction goals in case an area is not able to achieve 

attainment as designated by regulation. 

Degassing emissions occur when gas or vapor is removed from a storage tank, transport vessel or 

marine vessels. This generally occurs when a tank or vessel is being prepared for a change of 

service or as part of required maintenance. VOC emissions could total several thousand tons per 

year from tanks and vessels across an industrial area. In 2003 the state has estimated that 
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unreported or underreported floating roof landing loss emissions alone in the HGB area totaled 

approximately 7,250 tons in 2003. A subsequent analysis of degassing emissions in the DFW 

core counties estimated as much as 0.2 tons per day of VOC emissions would be reduced if the 

90 % control requirement were implemented. As a result, the State revised its VOC control 

regulations to help reduce emissions from these sources in the HGB area. 

EPA originally approved the Texas VOC regulations for Degassing or Cleaning of Stationary 

and Transport Vessels (30 TAC 115, Subchapter F, Division 3) as part the Texas SIP in 1997, 

under the 1-hour ozone standard. (62 FR 27966, May 22, 1997) That action approved VOC 

control measures on sources in the HGB and BPA areas and approved the same measures to be 

used as contingency measures in the DFW and El Paso areas if either of those nonattainment 

areas did not meet their ozone attainment dates. Subsequent changes to the Chapter 115 

Degassing and Cleaning regulations affecting the HGB and DFW areas were adopted into the 

SIP on March 29, 2010 (75 FR 15348), January 14, 2009 (74 FR 1903) and April 2, 2013 (78 FR 

19599). On May 21, 2010 the TCEQ invoked the contingency measure in the DFW area after the 

area failed to attain the 1997 ozone standard by June 15, 2010. (35 TexReg 4268, May 21, 2010) 

Affected tanks and vessels in the DFW area core counties, Collins, Dallas, Denton and Tarrant 

counties were required to comply with Chapter 115, Subchapter F, Division 3 control standards 

as of May 21, 2011. The State of Texas adopted the current revisions to 115 on February 11, 

2011 and submitted them to the EPA for inclusion into the SIP on February 18, 2011, including 

implementing contingency measures for sources in the core DFW counties. 

Three public hearings for the proposed revisions were held on September 7, 2010 in Austin, 

September 8, 2010 in Houston and September 9, 2010 in Ft. Worth. The hearings were not 

officially opened because none of the attendees indicated a desire to provide comment. However, 

the State did receive comments from EPA and others. EPA’s comment and others were 

addressed by the TCEQ. The State’s response to the comments can be found in the SIP submittal 

to EPA, which is part of the electronic docket (Docket number EPA-R06-OAR-2011-0079). 

Requirements to Control VOC Emissions 

The revision amends Chapter 115 of Title 30 of the Texas Administrative Code (30 TAC 115), 

Subchapter F Division 3 (Degassing of Stationary, Marine and Transport Vessels) by repealing 

the existing sections 115.541, 115.542 and 115.545, adopts new sections 115.540 – 115.542 and 

115.545 and amends existing sections115.543. 115.544, 115.546, 115.547 and 115.549. 

 Specifically the revision: Changed the title from “Degassing and Cleaning of Stationary, 

Marine and Transport Vessels” to “Degassing of Stationary, Marine and Transport Vessels” 

within the title of Subchapter F, Division 3. 

 Simplifies and clarifies the requirements of the regulation by consolidating emission 

specification and control requirements, defining terms commonly used in the division and 

making formatting changes to comply with current style and format requirements of the state. 

 Adopts additional options for demonstrating the VOC concentration in tanks or vessel being 

degassed do not increase above the concentration limits established in the control 

requirements section of the regulation; 
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 Requires recordkeeping to validate compliance; 

 Allows the use of a recirculation system to meet control requirements, with appropriate 

monitoring to assure effectiveness of the system; 

 Explicitly requires the flare flame, as well as the flare pilot, be lit at all times VOC vapors are 

vented to a flare for control during degassing operations; and 

 Allows the use of an option to limit the VOC concentration at the outlet of a control device to 

less than 500 ppm(v) at 0% oxygen, dry basis expressed as methane to demonstrate 

compliance. 

Table 1 is a summary of the revision by section. 

Table 1. Summary of Revision to 30 TAC §115 

Subchapter F, Division 3, Degassing of Stationary, Marine and 

Transport Vessels 

Title Revised Revision Reason Revision is 

Approvable 

Subchapter F, 

Division 3 Title 

Changed Title from “Degassing and Cleaning 

of Stationary, Marine and Transport Vessels” 

to “Degassing of Stationary, Marine and 

Transport Vessels” within the title of 

Subchapter F, Division 3. 

Does not change applicability or 

level of VOC reductions 

achieved by this rule. 

Section Revised Revision Reason Revision is 

Approvable

§115.540 

Applicability and 

Definitions 

New applicability and definitions added. 

Adds applicability and definition to clarify 

rules. Establishes consistency with other 

Chap §115 rules and improves readability. 

Additional section will clarify 

applicability of degassing 

requirements and 

responsibilities of affected 

owners and operators (O/O). 

§115.540(a) New applicability section. Clarifies 

applicability to degassing of storage tank, 

transport vessel and marine vessel containing 

volatile organic liquids with vapor pressure 

equal to or greater than 0.5 pounds per square 

inch absolute (psia). 

Helps define universe of 

affected sources. 

§115.540(a)(1) New applicability section. Defines 

applicability in the Beaumont-Port Arthur 

(BPA) area, as defined in §115.10. Applies to 

any storage tank, transport vessel, or marine 

vessel. 

Helps to clarify applicability of 

regulation in the Beaumont-Port 

Arthur area. 

§115.540(a)(2) New applicability section. Defines 

applicability in Dallas-Ft. Worth (DFW) area, 

as defined in §115.10. Applies to any storage 

tank, or transport vessel. 

Helps to clarify applicability of 

regulation in the Dallas-Ft. 

Worth area. 

§115.540(a)(3) New applicability section. Defines 

applicability in El Paso area, as defined in 

Helps to clarify that of 

regulation would apply to 
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§115.10. Applies to any storage tank, or 

transport vessel. 

sources in EL Paso are if the 

need arose in the future. 

§115.540(a)(4) New applicability section. Defines 

applicability in the Houston-GalvestonBrazoria (HGB) area, as defined in §115.10. 

Applies to any storage tank, transport vessel, 

or marine vessel. 

Helps to clarify applicability of 

regulation in the Houston–

Galveston-Brazoria area. 

§115.540(b) 

Definitions 

Definitions and terms have meaning 

commonly used in field of air pollution 

control, unless specifically defined in the 

Texas Clean Air Act. 

Helps to clarify terminology 

used in the section. 

§115.540(b)(1) Defines “Cleaning” to mean the process of 

washing or rinsing a storage tank, transport 

vessel, or marine vessel or removing sludge 

or rinsing liquid from a storage tan, transport 

vessel, or marine vessel. 

Helps to clarify terminology 

used in the section. 

§115.540(b)(2) Defines “Degassing” to mean the process of 

removing volatile organic vapor from a 

storage tank, transport vessel, or marine 

vessel during, or in preparation of, cleaning. 

Helps to clarify terminology 

used in the section. 

§115.540(b)(3) Defines “Drain-dry floating roof tank” to 

mean a floating roof tank designed to 

completely drain its contents to a sump and 

leave no free standing liquids in the tank or 

sump. 

Definition is consistent with API 

Technical Report 2568 and 

meets current industry 

terminology. 

§115.540(b)(4) Defines “Recirculation System” to mean a 

vapor tight system composed of piping, 

ductwork, connections, flow inducing 

devices, and a control device. The system 

conducts volatile organic vapor from a 

storage tank, transport vessel, or marine 

vessel to the control device and the exhaust 

from the control device back to the same tank 

or vessel. It does not include the tank or 

vessel itself. 

Helps to clarify terminology 

used in the section and fully 

describe the new control option. 

§115.540(b)(5) Defines “Storage Capacity” to mean the 

volume of a storage tank as determined by 

multiplying the internal cross-sectional area 

of the tank by the average internal height of 

the tank shell or the volume of a transport 

vessel or marine vessel as determined by the 

manufacturer’s original design capacity. 

Helps to clarify terminology 

used in the section. 

§115.540(b)(6) Defines “Storage Tank” to mean a stationary 

vessel, reservoir or container used to store 

volatile organic compounds. It does not 

include components that are not directly 

Helps to clarify terminology 

used in the section. 
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involved in the containment of liquids or 

vapors, subsurface caverns or porous rock 

reservoirs or process tanks or vessels. 

§115.540(b)(7) Defines “Vapor Tight” to mean the condition 

that exists when no component of a system 

has a leak greater than 500 parts per million 

expressed as methane measure using Method 

21 (40 CFR Part 60, Appendix A-7). 

Helps to clarify terminology 

used in the section. 

§115.541 

Emission 

Specifications 

Existing 115.541 repealed and replaced with 

a new, reformatted section. 

Previously approved 

requirements are incorporated 

into new §115.541 or in new 

§115.542. 

§115.541(a) Requires all volatile organic compounds 

(VOC) vapors be routed to a control device 

per requirements of §115.542. This section 

does not apply if measured VOC 

concentration is under 34,000 parts per 

million by volume (ppmv), as methane, or 

50% of lower explosive limit (LEL). 

This requirement will prevent or 

reduce VOC emissions by 

requiring VOC vapors to be 

controlled before venting to the 

atmosphere. Incorporates 

previously approved 

§115.541(a)(1)(A), (2)(A), and 

(b)(2) and does not impose new 

requirements. Clarifies 

applicability. 

§115.541(b) Prohibits intentional bypassing of a control 

device used to comply with this division. 

Requires repair of visible VOC leaks 

originating from the control device, or other 

associated product recovery device as soon as 

practical. 

Clarifies responsibility of O/O. 

Incorporates previously 

approved §115.541(a)(1)(D), 

(2)(D), and (b)(4) and does not 

impose new requirements. 

§115.541(c) Prohibits avoidable liquid or gaseous leaks, 

as detected by sight or sound, originating 

from degassing operations. 

Prevents direct contact of VOC 

vapors with atmosphere. 

Incorporates previously 

approved §115.541(a)(1)(C), 

(2)(C), and (b)(3) and does not 

impose new requirements. 

§115.541(d) Requires a transport vessel by kept vaportight at all times until the VOC vapors are 

routed to a control device. 

Prevents direct contact of 

uncontrolled VOC vapors with 

atmosphere. Incorporates 

previously approved 

§115.541(a)(2)(E) and does not 

impose new requirements. 

§115.541(e) Requires marine vessels to meet (e)(1) and 

(e)(2) below. 

Prevents direct contact of 

uncontrolled VOC vapors with 

atmosphere. Incorporates 

previously approved 

§115.541(b)(5), reformatted to 

meet current regulation writing 
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standards, and does not impose 

new requirements. 

§115.541(e)(1) Requires marine vessels to have all cargo 

tank closures properly secured or maintain a 

negative pressure within the vessel when a 

closure is opened 

Incorporates elements of 

previously approved 

§115.541(b)(5) and does not 

impose new requirements. 

§115.541(e)(2) Requires marine vessels to have all pressure 

or vacuum relief valves operating within 

certified limits, as specified by the 

classification society or flag state, until the 

VOC vapors are routed to a control device. 

Incorporates elements of 

previously approved 

§115.541(b)(5) and does not 

impose new requirements. 

§115.541(f) Requires VOC vapors from a floating roof 

storage tank that is not a drain-dry floating 

roof tank be routed to a control device as 

soon as practical. 

Reduces VOC emissions by 

limiting the time and amount of 

uncontrolled VOC vapors that 

are exposed to the atmosphere. 

Clarifies applicability. 

§115.541(f)(1) Requires VOC vapors from a floating roof 

storage tank that is not a drain-dry floating 

roof tank be routed to a control device as 

soon as practical, but no later than 24 hours 

after the tank has been emptied to the extent 

practical or the drain pump loses suction for a 

floating roof tank containing VOC liquids 

with a true vapor pressure greater than or 

equal to 1.5 psia under actual storage 

conditions. 

Reduces VOC emissions by 

limiting the time and amount of 

uncontrolled VOC vapors that 

are exposed to the atmosphere. 

§115.541(f)(2) Requires VOC vapors from a floating roof 

storage tank that is not a drain-dry floating 

roof tank be routed to a control device as 

soon as practical, but no later than 72 hours 

after the tank has been emptied to the extent 

practical or the drain pump loses suction for a 

floating roof tank containing VOC liquids 

with a true vapor pressure less than 1.5 psia 

under actual storage conditions. 

Reduces VOC emissions by 

limiting the time and amount of 

uncontrolled VOC vapors that 

are exposed to the atmosphere. 

§115.541(f)(3) Requires VOC vapors from a floating roof 

storage tank that is not a drain-dry floating 

roof tank be routed to a control device as 

soon as practical, but no later than the time 

limit specified in a permit issued under 

Chapter 116 of the title relating to Control of 

Air Pollution by Permits for New 

construction or Modification up to a 

maximum of 72 hours after the tank has been 

emptied to the extent practical or the drain 

pump loses suction. 

Reduces VOC emissions by 

limiting the time and amount of 

uncontrolled VOC vapors that 

are exposed to the atmosphere. 
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§115.542 

Control 

Requirements 

Existing 115.542 is repealed and replaced 

with a new, reformatted section. 

Previously approved 

requirements are incorporated 

into the new §115.542. 

§115.542(a) New Section details the options for control 

requirements used to comply with §115.541. 

(Note that existing requirements of 

115.542(a)(5) are repealed.) 

Reformatting options will not 

reduce the effectiveness of 

previously approved control 

options. Removing previously 

approved compliance options of 

§115.542(a)(5) will improve 

control of VOCs in the affected 

areas. 

§115.542(a)(1) Require control device by operated with an 

efficiency of at least 90% and in a manner 

consistent with how the device was operated 

during the control efficiency demonstration 

require in §115.544(c) of this title. 

Includes requirements 

previously approved in 

§115.541(a)(1)(B), (2)(B) and 

(b)(2) and clarifies O/O 

responsibilities in operating the 

control device. 

§115.542(a)(2) Allows control device to be a flare designed 

and operated in accordance with 40 CFR 

60.18(b)-(f) and that the flare be lit at all 

times when VOC vapors are routed to the 

flare. 

New control option will provide 

for effective control of VOC 

emissions, when this option is 

chosen. 

§115.542(a)(3) Allows control device to be a recirculation 

system that does not cause the pressure inside 

the tank or vessel to increase by more than 

one inch water pressure above atmospheric 

pressure at any time during the degassing 

operation. 

New control option will provide 

for effective control of VOC 

emissions by recirculation back 

to the source. 

§115.542(a)(4) Require VOC concentration at the outlet of 

the control device to be less than 500 ppm(v) 

at 0% oxygen, dry basis, expressed as 

methane. 

New control option will 

provided for effective control of 

VOC concentration at the outlet 

of a control device. 

§115.542(b) Requires VOC vapors be routed to a control 

device until the VOC concentration before 

the inlet to the control device is less than 

34,000 ppm(v) expressed as methane or less 

than 50% of the lower explosive limit. After 

one of the conditions has been satisfied, the 

tank or vessel may be vented to the 

atmosphere without control for the remainder 

of the degassing operation, except as 

specified in §115.544(b)(4) of this title. (Note 

that existing requirements of 115.542(b)(4) 

are repealed.) 

New subsection expands 

applicability of the requirement 

to areas other than HGB. 

Includes previously approved 

§115.542(a)(6) and (b)(5) that 

applied in HGB area. VOC 

reductions previously approved 

will not be altered. Expanding 

applicability to DFW, BPA and 

potentially El Paso will reduce 

the VOC emissions in those 

areas. Removing previously 

approved compliance options of 

§115.542(b)(4) will improve 
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control of VOCs in the affected 

areas. 

§115.542(c) Degassing equipment must be designed and 

operated to prevent avoidable liquid or 

gaseous VOC leaks. 

Clarifies O/O responsibility to 

prevent VOC leaks, both 

gaseous and liquid. Includes 

previously approved 

§115.542(a)(4) and b(3). 

§115.542(d) When degassing is done through the hatches 

or manways of a storage tank, all lines must 

be equipped with fittings that make vaportight connections and that are closed when 

disconnected or equipped to discharge 

residual VOC in the line into a closed 

recovery or disposal system after degassing 

or cleaning is complete. 

Improves overall reduction of 

VOC emissions by clarifying 

recovery or disposal system 

must be closed to minimize 

emissions. Includes previously 

approved §115.54(a)(3). 

§115.542(e) When degassing is done through the hatches 

of a transport vessel with a loading arm 

equipped with a vapor collection adapter, 

then pneumatic, hydraulic, or other 

mechanical means must be provided to force 

a vapor-tight seal between the adapter and the 

hatch. A means must be provided to 

minimize liquid drainage from the degassing 

or cleaning equipment when it is removed 

from the hatch or to accomplish drainage 

before such removal. 

Contains same requirements in 

previously approved 

§115.542(a)(2). No reduction in 

VOC emissions will result from 

this change. 

§115.542(f) When degassing is done through the hatches 

of a marine vessel with a loading arm 

equipped with a vapor collection adapter, 

then pneumatic, hydraulic, or other 

mechanical means must be provided to force 

a vapor-tight seal between the adapter and the 

hatch or a negative pressure inside the cargo 

tank must be maintained. A means must be 

provided to minimize liquid drainage from 

the degassing or cleaning equipment when it 

is removed from the hatch or to accomplish 

drainage before such removal. 

Contains same requirements in 

previously approved 

§115.542(b)(2). No reduction in 

VOC emissions will result from 

this change. 

§115.543 Alternate 

control Requirements 

Non-substantive wording changes are made 

to comply with TCEQ’s current rule 

formatting standards. 

No VOC reductions will result 

from these editorial changes. 

§115.544 Inspection, 

Monitoring and 

Testing Requirements 

Added “monitoring, and testing” to title of 

section to reflect changes made to the content 

of the section. 

§115.544(a) 

Inspection 

Changed wording to specify inspection 

requirements that apply to degassing 

Formatting change to regulation 

will not result in VOC emission 
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Requirements operations. changes. 

§115.544(a)(1) Non-substantive changes made to comply 

with current rule formatting standards. 

Formatting change. Contains 

previously approved 

§115.544(1). 

§115.544(a)(2) Non-substantive changes made to comply 

with current rule formatting standards. Also, 

removed duplicative requirement preventing 

bypassing of controls that is now found in 

§115.542. 

Formatting and editorial 

changes. Contains previously 

approved §115.544(2). Will not 

change VOC emission 

reductions overall. 

§115.544(b) 

Monitoring 

Requirements 

Added new subsection specify monitoring 

requirements applying during degassing and 

cleaning operations of storage tanks, 

transport vessels and marine vessels. 

Clarifies that monitoring once every 15 

minutes is sufficient to demonstrate 

compliance with the continuous monitoring 

requirements of this subsection. 

Regulation reformatting will not 

result in VOC emission changes, 

but should enable better 

compliance in the future. 

Clarification of continuous 

monitoring as equivalent to 

monitoring once every fifteen 

minutes is compatible with EPA 

guidance. 

§115.544(b)(1) New paragraph requires monitoring devices 

used to comply with requirement of this 

subsection be installed, calibrated, 

maintained, and operated according to the 

manufacturer’s instructions. 

Clarifies O/O responsibilities 

regarding operation of 

monitoring equipment. Will 

improve compliance. 

§115.544(b)(2) New paragraph requires the O/O to monitor 

any operational parameters necessary to 

demonstrate proper functioning of a control 

device when VOC vapors are routed to it. 

Reformatting existing regulatory 

requirements. Will not reduce 

VOC emission reduction 

previously achieved. Contains 

previously approved conditions 

in §115.546(2). 

§115.544(b)(2)(A) New subparagraph requires the O/O to 

continuously monitor exhaust gas VOC 

concentration of any carbon adsorption 

system to determine breakthrough. Also 

details O/O responsibilities when using 

carbon adsorption units as control devices. 

Reformatting existing regulatory 

requirements. Will not reduce 

VOC emission reduction 

previously achieved. Contains 

previously approved conditions 

in §115.546(2)(C). 

§115.544(b)(2)(B) New subparagraph requires the O/O to 

continuously monitor the inlet and outlet gas 

temperature of any catalytic incinerator used 

to comply with this section. 

Reformatting existing regulatory 

requirements. Will not reduce 

VOC emission reduction 

previously achieved. Contains 

the same requirements in the 

previously approved 

§115.546(2)(B). 

§115.544(b)(2)(C) New subparagraph requires the O/O to 

continuously monitor the outlet gas 

temperature of a condensation system to 

ensure that the temperature is below the 

Will improve compliance with 

regulatory requirements when 

condensation system is used as a 

compliance option. 
10 

manufacturer’s recommended operating 

temperature for controlling the VOC vapors 

routed to the device. Clarifies that this 

applies when condensation device is used as 

part of a recirculation system. 

§115.544(b)(2)(D) New subparagraph requires the O/O to 

continuously monitor the exhaust gas 

temperature immediately downstream of a 

direct-flame incinerator. 

Reformatting existing regulatory 

requirements. Will not reduce 

VOC emission reduction 

previously achieved. Contains 

previously approved conditions 

in §115.546(2)(A). 

§115.544(b)(2)(E) New subparagraph applies to flares used as a 

control device. 

New subparagraph provides 

compliance demonstration 

options when using a flare as a 

control device. Expected to 

improve compliance. 

§115.544(b)(2)(E)(i) Requires the O/O to continuously monitor the 

net heating value of the gas stream routed to 

the flare. 

Expected to verify effective 

VOC emission reductions. 

§115.544(b)(2)(E)(ii) Requires the O/O to continuously monitor the 

total volume of supplemental fuel added to 

the gas stream routed to the flare and 

continuously maintain sufficient 

supplemental fuel to meet the minimum net 

heating value requirements in 40 CFR §60.18 

assuming the net heating value of the 

degassed VOC vapors routed to the flare is 

equivalent to a level corresponding to 50% of 

the LEL. 

Expected to verify effective 

VOC emission reductions. 

§115.544(b)(2)(E)(iii) As an alternative to §115.544(b)(2)(ii), O/O 

may use calculations to demonstrate the net 

heating value of the VOC vapors routed to 

the flare will not drop below the minimum 

net heating value requirement in 40 CFR 

60.18, until the concentration of VOC in the 

vapor being routed to the flare is less than the 

concentration limits in §115.542(b). 

Expected to verify effective 

VOC emission reductions. 

Consistent with current federal 

requirements for use of a flare as 

a control device. 

§115.544(b)(2)(E)(iv) If a non-assisted flare qualifying per 

requirements of 40 CFR §60.18(c)(3)(i), the 

O/O may continuously monitor the hydrogen 

content of the gas stream routed to the flare 

and continuously meet the minimum 8.0% by 

volume hydrogen content requirement in lieu 

of (i)-(iii) above. 

Expected to add flexibility in 

compliance and verify effective 

VOC emission reductions. 

Consistent with current federal 

requirements for use of a flare as 

a control device. 

§115.544(b)(2)(F) For any control device used to comply with 

the optional exhaust gas concentration limit 

Expected to verify effective 

VOC emission reductions. 
11 

in § 114.442(a)(4), the O/O shall test the 

exhaust gas VOC concentration within one 

hour of beginning degassing operations using 

(i)-(ii) below. 

Consistent with current federal 

guidelines 

§115.544(b)(2)(F)(i) Allow use of 40 CFR 60, Appendix A, 

Method 18,§§8.2.11-8.2.1.4 integrated bag 

sampling procedure and a total hydrocarbon 

analyzer meeting specification of Method 21. 

Expected to verify effective 

VOC emission reductions. 

Consistent with current federal 

testing requirements. 

§115.544(b)(2)(F)(ii) Alternatively to §115.544(b)(2)(F)(i), O/O 

may monitor the exhaust gas VOC 

concentrations using 40 CFR 60, Appendix 

A, Method 25A. 

Expected to verify effective 

VOC emission reductions. 

Consistent with current federal 

testing requirements. 

§115.544(b)(2)(G) O/O shall continuously monitor the 

combustion chamber temperature of a 

thermal oxidizer or vapor combustor and if 

necessary to comply with §115.544(c)(3), 

continuously monitor the gas flow rate into 

the thermal oxidizer to determine the 

combustion chamber residence time. 

Expected to verify effective 

VOC emission reductions. 

§115.544(b)(2)(H) New subparagraph applies to recirculation 

systems used to comply with this section. 

Expected to ensure VOC 

releases will not occur when 

recirculation systems are used to 

comply with this regulation. 

§115.544(b)(2)(H)(i) O/O shall continuously monitor the pressure 

in the tank or vessel or continuously monitor 

the gas flow rate at the inlet an outlet of the 

control device. 

Expected to ensure adequate 

circulation of gas through 

control device. 

§115.544(b)(2)(H)(ii) Monitor all components of the recirculation 

system, including all valves and connectors, 

for VOC leaks using Method 21, 40 CFR part 

60, Appendix A-7, procedures. Monitoring 

shall begin within one hour after beginning 

degassing operation. Define leak as a 

screening concentration greater than 500 

ppm(v), as methane, above background. 

Expected to prevent or control 

fugitive emission leaks in 

equipment used to circulate 

VOC vapors to the control 

device and back to the tank or 

vessel being degassed or 

cleaned. 

§115.544(b)(2)(I) New subparagraph applies to internal 

combustion engines used to comply. O/O 

required to continuously monitor the engine 

exhaust as oxygen content throughout the 

degassing operation. 

Expected to assure adequate 

VOC control when IC engines 

used as control option. 

§115.544(b)(2)(J) New subparagraph applies to control devices 

not listed in this paragraph. 

Expected to assure adequate 

VOC control when alternate 

control devices are used as 

control option. 

§115.544(b)(3) New paragraph requires VOC concentration 

be monitored to demonstrate VOC 

Clarifies monitoring 

requirements to be followed 
12 

concentration or percent LEL threshold 

established in §115.542(b) is achieved before 

venting to atmosphere, without control, 

allowed using (A) or (B) below. 

before venting tank or vessel to 

atmosphere without control 

during degassing and/or 

cleaning operations. 

§115.544(b)(3)(A) Requires VOC concentration to be monitored 

once per minute for at least five minutes, and 

all measurements must be less than the VOC 

concentration limits in §115.542(b). 

Clarifies monitoring 

requirements to be followed 

before venting tank or vessel to 

atmosphere without control 

during degassing and/or 

cleaning operations. 

§115.544(b)(3)(B) Over a five minute period using the 

integrated bag sampling procedure in Method 

18, (40 CFR Part 60, Appendix A) §§8.2.1.1-

8.2.1.4 and the integrated measurement must 

be less than the VOC concentration limit in 

§115.542(b). 

Clarifies monitoring 

requirements to be followed 

before venting tank or vessel to 

atmosphere without control 

during degassing and/or 

cleaning operations. 

§115.544(b)(4) After demonstrating compliance with the 

limits established in §115.542(b), O/O must 

comply with one of the following conditions: 

Minor reformatting of 

previously approved language 

will not result in VOC emission 

increases within the state. 

§115.544(b)(4)(A) The O/O must monitor the VOC 

concentration inside the tank or vessel once 

every 12 hours while venting to atmosphere 

without control until five consecutive 

measurement collected at 12 hour intervals 

are measure at less than 34,000 ppm(v) 

expressed as methane or less than 50% of the 

LEL expressed as methane. The 

measurement in (3) above maybe considered 

the first measurement. 

Contains conditions found in 

115.542(a)(6) and (b)(5) for 

HGB area and extends these 

requirements to all affected 

areas in the state, including 

BPA, DFW, and El Paso. 

§115.544(b)(4)(A)(i) If uncontrolled venting to the atmosphere has 

been suspended for more than four hours, the 

VOC concentration inside the tank or vessel 

must be measured upon restart of the 

degassing and cleaning operation. 

Expected to improve compliance 

and reduce VOC emissions in 

the affected areas. 

§115.544(b)(4)(A)(ii) If any of the VOC concentration 

measurements equal or exceed 34,000 

ppm(v) expressed as methane or 50% of the 

LEL expressed as methane, the tank or vessel 

must be routed to a control device until the 

VOC concentration before the inlet to the 

control device is below 34,000 ppm(v) 

expressed as methane or less than 50% of the 

LEL expressed as methane. 

Expected to improve compliance 

and reduce VOC emissions in 

the affected areas. 

§115.544(b)(4)(A)(iii) New subparagraph states if measure VIOC 

concentration is less than 6,800 ppm(v) 

It is not expected that 

concentrations above the 34,000 
13 

expressed as methane or 10% of LEL then no 

further VOC concentration measurements are 

required. 

ppm(v), as methane, control 

threshold will be reached if 

concentrations below 6,800 

ppm(v), as methane, are 

achieved. 

§115.544(b)(4)(B) O/O may vent the tank or vessel to the 

atmosphere without control or VOC 

measurement with the VOC concentration 

inside the tank or vessel is less than 6,800 

ppmv, as methane, or 10% of the LEL. 

Compliance with this option 

should not result in an 

exceedance of the previously 

approved 34,000 ppm(v), as 

methane, or 50% of LEL, 

concentration limit that requires 

VOC controls within 12 hours. 

§115.544(b)(5) ED may approve minor modifications to 

monitoring methods in this section if 

validated using 40 CFR Part 60, Appendix A, 

Method 301. 

Minor modifications to 

approved monitoring methods 

will provide for O/O flexibility 

in demonstrating compliance 

and is not expected to result in 

VOC emission increases within 

the state. 

§115.544(b)(6) New paragraph clarifying sampling locations 

for performing required monitoring. 

This change is expected to aid in 

regulatory compliance and 

should result in reduced VOC 

emissions within the affected 

areas. 

§115.544(c) Testing 

Requirements 

New paragraph requires O/Os to comply with 

the following testing requirements. 

Paragraph specifies testing 

requirements that apply to O/O 

using a control device to comply 

with the emission specification 

of 115.541. 

§115.544(c)(1) For a control device used to comply with the 

requirements in §115.542(a)(1) of this title an 

initial control efficiency demonstration must 

be conducted in accordance with the 

approved test methods in §115.545 of this 

title (relating to Approved Test Methods) and 

the device must be retested within 60 days 

after any modification that could reasonably 

be expected to decrease the efficiency of a 

control device or before it is used for 

compliance with 15.542(a)(1), whichever is 

longer. 

This requirement will not reduce 

the efficiency of the control 

device and will not result in 

increased VOC emissions in the 

affected areas. 

§115.544(c)(2) For a portable control device used to comply 

with the requirement in §115.542(a)(1) of 

this title, a periodic control efficiency 

demonstration must be conducted at least 

once every 60 months in accordance with the 

Periodic assurance of the 

efficiency of the control device 

should improve the long term 

emission reductions of the 

regulation. 
14 

approved test methods in §115.545 of this 

title. 

§115.544(c)(3) For a portable thermal oxidizer or vapor 

combustor, the periodic control efficiency 

demonstration in paragraph (2) of this 

subsection will not be required if the 

combustion chamber temperature is at least 

1,400 degrees Fahrenheit and the flow rate of 

the VOC vapors routed to the device is 

limited to assure at least a 0.5 second 

combustion chamber residence time at all 

times when the device is in use. 

Exemption from the 60 month 

testing requirements if a thermal 

oxidizer or vapor combustor 

maintains the designated firebox 

temperature and residence time 

will assure VOC control and 

reduce VOC emissions in the 

affected areas. 

§115.545 Approved 

Test Methods 

Repeals previously approved 115.545 to 

allow for reformatting. Creates new section 

115.545 requiring compliance be determine 

by applying one or more of the following test 

methods or procedures. 

Minor reformatting will not alter 

substance of previously 

approved 115.545. 

§115.545(1) New paragraph requires use of Methods 1-4 

(40 CFR 60, Appendix A) to determine flow 

rates. Contains the same requirement as the 

previously approved §115.545(1) with nonsubstantive changes to conform to current 

Rule formatting standards. 

Contains previously approved 

115.545(1). 

§115.545(2) Allows use of Methods 3, 3A, or 3B (40 CFR 

60, Appendix A) to determine exhaust gas 

oxygen concentration for making any oxygen 

corrections necessary for §115.541(a)(4). 

Consistent with published EPA 

regulations and guidance. 

§115.545(3) New paragraph allows use of Method 18 (40 

CFR 60, Appendix A) to determine gaseous 

organic compound emissions by gas 

chromatography. 

Contains previously approved 

115.545(2) with non-substantive 

changes necessary to comply 

with current rule formatting 

standards. 

§115.545(3)(A) New subparagraph requires only one bag 

sample to be collected for each concentration 

measurement if Method 18 is used to 

demonstrate compliance with the VOC 

concentration monitoring requirements in 

§115.542(b) and §115.544(b)(4). 

Contains the same requirement 

in previously approved 

paragraph §115.545(11)(B) for 

use in HGB area and applies it 

to other areas affected by this 

regulation. 

§115.545(3)(B) New subparagraph requires VOC 

concentration to be determined by using the 

integrated bag sampling procedure in 

§8.2.1.1 – 8.2.1.4. of Method 18 is used to 

demonstrate compliance with the VOC 

concentration monitoring requirement in 

§115.544(b)(2)(F) for internal combustion 

engines or any control device used to comply 

Consistent with published EPA 

regulations and guidance. 
15 

with the option in §§115.542(a)(4) to limit 

exhaust concentration. 

§115.545(4) New paragraph allows use of Method 19 (40 

CFR 60, Appendix A) to determine exhaust 

gas flow rates on combustion control devices 

in lieu of using Methods 1-4. 

Consistent with published EPA 

regulations and guidance. 

§115.545(5) New paragraph allows use of Method 21 (40 

CFR 60, Appendix A-7) to determine VOC 

leaks. Allows use of an instrument meeting 

specification and calibration requirement in 

Method 21 and the response factor criteria in 

§8.1 of Method 21 to demonstrate 

compliance with VOC concentration 

monitoring requirements in §115.542(b) and 

§115.542(b)(4). 

Expected to reduce VOC 

emissions through and LDAR 

program for degassing 

operations. This new 

subparagraph contains 

requirement in the previously 

approved §115.545(6) and 

previously approved 

§115.545(11)(A). 

§115.545(6) New paragraph allows use of Method 25 (40 

CFR 60, Appendix A) to determine total 

gaseous non-methane organic emissions as 

carbon. 

Contains same requirements of 

previously approved 

§115.545(3). 

§115.545(7) New paragraph allows use of Method 25A or 

Method 25B (40 CFR 60, Appendix A) to 

determine total gaseous organic 

concentrations suing flame ionization or 

nondispersive infrared analysis. 

Contains same requirement as 

previously approved 

§115.545(4). 

§115.545(8) New paragraph allows use of Method 27 (40 

CFR 60, Appendix A) to determine tanktruck leaks. 

Contains same requirement as 

previously approved 

§115.545(8). 

§115.545(9) New paragraph allows use of a portable 

oxygen analyzer calibrated, maintained, and 

operated according to the manufacturer’s 

instructions be used to determine exhaust gas 

oxygen concentration for making any oxygen 

corrections necessary for §115.542(a)(4) in 

lieu of using Methods 3, 3A or 3B. 

Not expected to result in VOC 

emissions increase in affected 

areas. 

§115.545(10) New paragraph allows additional test 

procedures described in 40 CFR 60.503(b)–

(d) to be used for determining compliance for 

bulk gasoline terminals. 

Contains the same requirements 

previously approved in 

§115.545(5). 

§115.545(11) New paragraph requires the true vapor 

pressure be determined using ASTM Test 

Method D323, D2879, D4953, D5190, or 

D5191 for measurement of Reid vapor 

pressure, adjusted for actual storage 

temperature in accordance with API 

Publication 2517, 3rd edition, 1989. For 

purposes of temperature correction, the actual 

New options for determining 

true vapor pressure should 

provide more accurate emission 

determinations of VOC in the 

affected areas. Contains same 

requirements as previously 

approved §115.545(7). 
16 

storage temperature shall be used. Actual 

storage temperature of an unheated tank or 

vessel may be determined using the 

maximum local monthly average ambient 

temperature as reported by the National 

Weather Service. Actual temperature of a 

heater tank must be determined using either 

the measured temperature or the temperature 

set point of the tank or vessel. 

§115.545(12) New paragraph stipulates use of test 

procedures in 40 CFR 63.565(c) or 61.304(f) 

to determine marine vessel vapor tightness. 

Contains same requirement in 

previously approved 

§115.545(9). 

§115.545(13) New paragraph allows lower explosive limit 

detectors to be used for concentration 

measurement required by §115.542(b) and 

§115.544(b)(3) and (4) if the detector is 

calibrated and maintained according to the 

manufacturer’s specifications. 

Contains same requirements in 

previously approved 

§115.545(11)(F) for the HGB 

area and extends the requirement 

to other affected areas of the 

state. 

§115.545(14) New paragraph allow minor modifications to 

the test methods in the section if approved by 

the TCEQ executive director. 

Contains same requirement in 

previously approved 

§115.545(10). 

§115.545(15) New paragraph allows test methods other 

than those specified in this section be used if 

validated by 40 CFR 63, Appendix A, Test 

Method 301 and approved by the TCEQ 

executive director. 

Provides consistency with other 

sections of §115. 

§115.546, 

Recordkeeping and 

Notification 

Requirements 

Title changed from “Monitoring and 

Recordkeeping Requirements” to 

Recordkeeping and Notification 

Requirements” to reflect proposed changes to 

section, relocating the monitoring 

requirements to §115.544 and require 

notification of degassing operations. 

§115.546(a) 

Recordkeeping 

Requirements 

 Subsection (a) modified to specify 

recordkeeping requirements for this division. 

Clarifies applicable sources and expands 

record retention time from two years to five 

years. 

Promotes consistency in record 

retention schedules. 

§115.546(a)(1) Non- substantive changes made to comply 

with current rulemaking format. 

Contains previously approved 

§115.545(1). 

§115.546(a)(1)(A) Non- substantive changes made to comply 

with current rulemaking format. 

Contains previously approved 

§115.545(1)(A). 

§115.546(a)(1)(B) Non- substantive changes made to comply 

with current rulemaking format. 

Contains previously approved 

§115.545(1)(B). 

§115.546(a)(1)(C) Non- substantive changes made to comply 

with current rulemaking format. 

Contains previously approved 

§115.545(1)(C). 
17 

§115.546(a)(1)(D) Reworded to clarify O/Os required to 

maintain records showing compliance with 

§115.544(b)(3) before venting tank or vessel 

to the atmosphere. 

Clarifies the intent of previously 

approved §115.546(4) to 

maintain results of any testing 

conducted according to 

§115.545 includes maintaining 

records to demonstrate 

compliance with the VOC 

concentration limits in 

§115.542. 

§115.546(a)(1)(E) New paragraph requiring O/Os maintain 

records showing compliance with 

§115.544(b)(4) before venting tank or vessel 

to the atmosphere. 

Includes requirements of 

previously approved 

§115.546(1)(D). 

§115.546(a)(2) New paragraph requiring O/Os maintain 

records showing compliance with 

§115.544(b)(2). 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas. 

§115.546(a)(2)(A) New subparagraph requiring O/Os maintain 

records of VOC concentration measurements 

required by §115.544(b)(2)(A) for carbon 

adsorption systems. 

Contains previously approved 

§115.545(2)(C). 

§115.546(a)(2)(B) New subparagraph requiring O/Os maintain 

records of the continuous monitoring of inlet 

and outlet gas temperature of a catalytic 

incinerator required by §115.544(b)(2)(B) for 

carbon adsorption systems. 

Contains previously approved 

§115.545(2)(B). 

§115.546(a)(2)(C) New subparagraph requiring O/Os maintain 

records of the continuous monitoring of the 

outlet gas temperature to ensure that the 

temperature is below the manufacturer’s 

recommended operating temperature of 

controlling the VOC vapors that are routed to 

a condensation system as required by 

§115.544(b)(2)(C). 

Expected to enhance compliance 

with the regulation and assure 

VOC reductions in affected 

areas when condensation 

systems are in use as control 

devices. 

§115.546(a)(2)(D) New subparagraph requiring O/Os maintain 

records of the exhaust gas temperature 

immediately downstream of a direct-flame 

incinerator as required by 

§115.544(b)(2)(D). 

Contains previously approved 

§115.545(2)(A). 

§115.546(a)(2)(E) New subparagraph requiring O/Os maintain 

records of the continuous monitoring of the 

net heating value of the VOC vapors routed 

to the flare, the supplemental fuel added to 

the VOC vapors routed to the flare or the 

engineering calculations required by 

§115.544(b)(2)(E). 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas when flares are 

used to comply with the 

regulation. 

§115.546(a)(2)(F) New subparagraph requiring O/Os maintain Expected to enhance compliance 
18 

records of the hourly monitoring of the 

exhaust gas VOC concentration required by 

§115.544(b)(2)(F) to limit exhaust gas 

concentration. Also requires O/Os to 

maintain a record of the monitoring method 

used to determine the VOC concentration. 

and assure VOC reductions in 

affected areas when VOC 

concentration in control device 

exhaust gas is used to 

demonstrate compliance. 

§115.546(a)(2)(G) New subparagraph requiring O/Os maintain 

records of the continuous monitoring of the 

combustion chamber temperature of a 

thermal oxidizer or vapor combustor, as 

required by §115.544(b)(2)(G). Also requires 

O/O maintain records of the continuously 

monitoring of the gas flow rate into the 

thermal oxidizer or vapor combustor to 

determine the residence time if necessary to 

demonstrate compliance with §115.544(c)(3).

Expected to enhance compliance 

and assure VOC reductions in 

affected areas when thermal 

oxidizers are used to comply. 

§115.546(a)(2)(H) New subparagraph requiring O/Os maintain 

records of the continuous monitoring of the 

pressure inside the tank or vessel or the 

continuous monitoring of the gas flow rate at 

the inlet and outlet as required by 

§115.544(b)(2)(H). Also requires O/O 

maintain records of the Method 21 

monitoring for VOC leaks within one hour 

after beginning any degassing or cleaning 

operation, including the VOC measurement 

and the time the monitoring began. 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas when 

recirculation of vapor is used to 

comply with the regulation. 

§115.546(a)(2)(I) Requires O/Os maintain records of 

continuous engine exhaust gas oxygen 

content monitoring require by 

§115.544(b)(2)(l) when IC engine is used to 

comply. 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas when an IC 

engine is used to comply with 

the regulation. 

§115.546(a)(2)(J) Requires O/Os maintain records of the 

continuous operation parameter monitoring 

required in §115.544(b)(2)(J) sufficient to 

demonstrate proper functioning of the control 

device not listed in this paragraph. 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas when an alternate 

means of compliance is used to 

comply with the regulation. 

§115.546(a)(3) Non-substantive changes made to comply 

with current rule formatting standards. Also 

re-letters reference to §115.544 to 

§115.544(a) to reflect changes being made to 

§115.544. 

Non- substantive changes made 

to comply with current 

rulemaking format. 

§115.546(a)(4) Non-substantive changes made to comply 

with current rule formatting standards. Also 

requires records contain all applicable 

requirements from the TCEQ’s Sampling 

Clarifies the information the 

commission expects to be 

included in records of any 

testing conducted according to 
19 

Procedures Manual, Chapter 14.0, contents of 

Sampling Report (January 2003, revision 

one). 

the approved test methods in 

§115.545. 

§115.546(a)(5) New subparagraph requiring O/Os maintain 

records of the manufacturer’s instructions for 

installation, calibration, maintenance, and 

operation for any monitoring device used to 

comply with the requirements of the division. 

Expected to enhance compliance 

and assure VOC reductions in 

affected areas. 

§115.546(b) 

Notification 

Requirements 

New paragraph requiring O/Os in the HGB 

area notify TCEQ regional office of 

upcoming degassing or cleaning operations 

when requested. 

This notification requirement is 

expected to facilitate 

enforcement of the rule in the 

HGB area by allowing 

investigators to observe 

degassing operations. 

§115.547 Exemptions Non-substantive changes to §115.547 are 

made to comply with current TCEQ rule 

formatting standards. 

§115.547(1) Deletes existing language to clarify rule’s 

applicability to storage tanks, transport 

vessels and marine vessels storing volatile 

organic liquids with a true vapor pressure 

greater than or equal to 0.5 psia under actual 

storage conditions. New language specifies 

any storage tank with capacity of less than 

1,000,000 gallons is exempt except in the 

HGB area as noted in (A) and (B) below. 

Contains previously approved 

portion of §115.547(2) relating 

to storage tanks. 

§115.547(1)(A) New subparagraph applies rule to storage 

tanks with storage capacity greater than or 

equal to 250,000 gallons but less than 

1,000,000 after January 1, 2009 in the HGB 

area. 

New subparagraph is expected 

to reduce VOC emissions in the 

HGB area. 

§115.547(1)(B) New subparagraph applies rule to storage 

tanks with storage capacity greater than or 

equal 75,000 gallons but less than 250,000 

gallons and storing materials with true vapor 

pressure greater than 2.6 psia after January 1, 

2009 in the HGB area. 

New subparagraph is expected 

to reduce VOC emissions in the 

HGB area. 

§115.547(2) New paragraph exempts transport vessels in 

BPA, DFW, El Paso and HGB areas with a 

storage capacity of less than 8,000 gallons. 

Contains portions of previously 

approved §115.547(2) that relate 

to transport vessels. 

§115.547(3) New paragraph exempts marine vessels in 

BPA, and HGB areas with a storage capacity 

of less than 420,000 gallons. Also deletes 

reference to 10,000 barrel in the previously 

approved §115.547(2) to be consistent with 

the format of volume references in this 

Contains portions of previously 

approved §115.547(2) that relate 

to marine vessels. 
20 

section. 

§115.547(4) Renumbered paragraph §115.547(3) with 

non-substantive changes to comply with 

current rulemaking formats. 

Contains previously approved 

paragraph §115.547(3). 

§115.547(5) Renumbered paragraph §115.547(4) with 

non-substantive changes to comply with 

current rulemaking formats. Limits 

exemption to 30 calendar days after damage 

to tank occurs. Also amended to indict 

requirement in existing §115.541(b) and 

§115.542(b) are now §115.541and §115.542. 

Contains previously approved 

paragraph §115.547(4). 

§115.547(6) Renumbered §115.547(5) with nonsubstantive changes to comply with current 

rulemaking formats. 

Contains previously approved 

paragraph §115.547(5). 

§115.549 Compliance 

Schedules 

Change title from “Counties and Compliance 

Schedules” to “Compliance Schedules” 

§115.549(a) Non-substantive changes to comply with 

current rulemaking formats and clarify rule 

remains in effect for previously affected 

areas. 

Clarifies compliance schedules 

for affected areas. Will not result 

in increased VOC emissions in 

the state. 

§115.549(b) Non-substantive changes to comply with 

current rulemaking format. 

Also, sets May 21, 2011 as final date for 

O/Os in Collin, Dallas, Denton and Tarrant 

Counties to be in compliance with this 

regulation. 

Establishing compliance date for 

DFW area counties is expected 

to result in decreased VOC 

emissions in the DFW area. 

§115.549(c) Non-substantive changes to comply with 

current rulemaking format. 

Not expected to result in any 

change in VOC emissions. 

§115.549(d) Non-substantive changes to comply with 

current rulemaking format and re-letters 

references to previously approved 

§115.542(a)(6), (b)(5), and §115.546(1)(D) 

as §115.542(b), §115.544(b)(4) and 

§115.546(a)(1)(E), respectively. 

Not expected to result in any 

change in VOC emissions. 

For more information on the requirements please see the appendices or 30 TAC 115, Subchapter 

F, Miscellaneous Industrial Sources Division 3 (Degassing of Storage Tanks, Transport Vessels, 

and Marine Vessels). Appendix 1 is excerpted from the February 11, 2011 Texas Register. The 

Texas Register can be accessed through the internet at 

http://texinfo.library.unt.edu/texasregister/. The Texas Administrative Code rules can be 

accessed through the internet at: www.tceq.state.tx.us/rules/indxpdf.html. 

Evaluation of Revision 

EPA has evaluated the Chapter 115 revision and finds they enhance the SIP by reducing 

emissions from VOC storage tanks, transport vessels and marine vessels in Collin, Dallas, 
21 

Denton and Tarrant counties by requiring additional controls on VOC emissions from these 

sources as discussed above. These reduced emissions will help lower ozone levels in the DFW 

area. The rulemaking subjects owners or operators of VOC storage tanks, transport vessels, and 

marine vessels located in the DFW 1997 8-hour ozone nonattainment area to more stringent 

control, monitoring, and recordkeeping requirements. The rulemaking also enhances compliance 

with existing rules by clarifying applicability, compliance, recordkeeping and monitoring 

requirements for sources subject to the regulation. 

As shown in the Table 1, these revisions improve TCEQ’s rules. These rules were previously 

approved by EPA as enhancing the state’s SIP by imposing VOC reductions in applicable areas 

most recently in 2010. With these improvements, the rules will continue to ensure the Act’s 

requirements are met. Under CAA section 110(l) EPA may not approve a SIP revision if the 

revision would interfere with any applicable requirement concerning attainment or any other 

applicable requirement of the CAA. EPA approval of the revision will not interfere with any 

applicable requirement concerning attainment or any other applicable requirement of the CAA 

including RACT requirements. 

Recommendation 

It is recommended that the revision to the Texas SIP be approved because the revisions improve 

the rules that were previously approved resulting in additional VOC reductions and insuring that 

RACT is still met for these source categories. 
22 

Appendices 

Appendix 1 – Excerpt from the February 11, 2011Texas Register (36 TexReg 809) 

Appendix 2 –Title 30 of the Texas Administrative Code Subchapter F (Miscellaneous Industrial 

Sources) 
23 

Appendix 1 – Excerpt from the February 11, 2011Texas Register (36 TexReg 809) 

Chapter 115. CONTROL OF AIR POLLUTION FROM VOLATILE ORGANIC 

COMPOUNDS 

Subchapter F, Miscellaneous Industrial Sources 

Division 3, Degassing of Storage Tanks, Transport Vessels, and Marine Vessels 

The Texas Commission on Environmental Quality (TCEQ or commission) adopts the repeal of 

§§115.541, 115.542, and 115.545; adopts new §§115.540 - 115.542 and 115.545; and adopts the 

amendments to §§115.543, 115.544, 115.546, 115.547, and 115.549. 

Sections 115.540 - 115.542, 115.544 - 115.546, and 115.549 are adopted with changes to the 

proposed text as published in the August 13, 2010, issue of the Texas Register (35 TexReg 

6976). Section 115.543 and §115.547 are adopted without changes and the text will not be 

republished. 

The adopted amended, repealed, and new sections will be submitted to the United States 

Environmental Protection Agency (EPA) as revisions to the state implementation plan (SIP). 

BACKGROUND AND SUMMARY OF THE FACTUAL BASIS FOR THE ADOPTED 

RULES 

Chapter 115, Subchapter F, Division 3, regulates the degassing of storage tanks, transport 

vessels, and marine vessels. Compliance with the rules is currently required for affected sources 

in the Houston-Galveston-Brazoria ozone nonattainment area and the Beaumont-Port Arthur 

area. Although not currently effective, the Chapter 115 degassing rules also apply in El Paso 

County as contingency measures that could become effective if the commission determines the 

rules are necessary to comply with federal air quality standards. 

On May 21, 2010, the commission published notice in the Texas Register (35 TexReg 4268) 

requiring affected sources in Collin, Dallas, Denton, and Tarrant Counties to comply with the 

current Chapter 115 degassing rules no later than May 21, 2011. The rules in Chapter 115, 

Subchapter F, Division 3, were adopted as a contingency measure for these four counties in the 

Dallas-Fort Worth area on April 27, 1994, and published in the Texas Register on May 13, 1994 

(19 TexReg 3703). The contingency rules are being implemented as a result of the Dallas-Fort 

Worth area failing to attain the 1997 eight-hour ozone National Ambient Air Quality Standard 

(NAAQS) by the June 15, 2010, attainment deadline based on monitoring data. On August 9, 

2010, the EPA published a proposal to reclassify the nine-county Dallas-Fort Worth area as a 

serious nonattainment area under the 1997 eight-hour ozone NAAQS (75 FR 47746). 

Beginning in April 2009, a series of petitions for rulemaking were submitted to the commission 

regarding the more stringent degassing requirements that became effective in the HoustonGalveston-Brazoria area on January 1, 2009. Although, these petitions were withdrawn before 

the scheduled agenda for the commission’s consideration while evaluating the merit of these 

petitions, staff identified several portions of the degassing rules that could be clarified to 
24 

facilitate compliance and enforcement. In the following months, numerous questions were also 

raised by affected regulated entities, consultants, and vendors regarding compliance with the 

requirements in Chapter 115, Subchapter F, Division 3. The adopted rulemaking addresses the 

concerns raised by stakeholders by revising Chapter 115, Subchapter F, Division 3, to clarify the 

degassing rule requirements for sources in all affected areas, provide additional flexibility for 

affected owners or operators by allowing for the use of alternative control options, and facilitate 

rule enforcement. 

General Clarification of Rule Requirements 

The adopted rulemaking reformats the existing rules in Chapter 115, Subchapter F, Division 3, to 

simplify and clarify the requirements. Some of these formatting changes include adopting new 

§115.540 to specify the rule applicability and define terms commonly used in this division, 

repealing §115.541 and §115.542, and adopting new §115.541 and §115.542 to consolidate the 

emission specifications and control requirements. In addition, the adopted rules make other nonsubstantive revisions to update the rule language to current Texas Register style and format 

requirements. Additional details regarding the general reformatting and clarification changes are 

discussed in the SECTION BY SECTION DISCUSSION portion of this preamble. 

Additional Control Options 

One concern raised by stakeholders was that the existing rules do not adequately address the use 

of several types of control technologies that could achieve equivalent volatile organic 

compounds (VOC) emission reductions. The existing rules require that VOC vapors be routed to 

a device that maintains a control efficiency of at least 90%. The adopted rules specifically 

provide for the use of the following equivalent control options to comply with the emission 

specifications in the rules. 

The adopted rules allow for the use of flares that are designed and operated in accordance with 

40 Code of Federal Regulations (CFR) §60.18(b) - (f) (as amended through December 22, 2008 

(73 FR 78209)). In addition to complying with the operating parameters in 40 CFR §60.18, the 

commission is requiring that flares used during degassing operations must be lit at all times when 

VOC vapors are routed to the device. Although 40 CFR §60.18 requires the pilot to be lit at all 

times and requires monitoring of the flare pilot flame, the commission is also specifically 

requiring the flare flame to be lit to clarify that the intent of the rules is for both the flare flame 

and the pilot to be lit at all times when VOC vapors are routed to the device. 

The existing rules require VOC vapors from affected tanks or vessels to be routed to a control 

device until the concentration is less than 34,000 parts per million by volume (ppmv), expressed 

as methane. However, as the VOC vapor concentration approaches 34,000 ppmv, there may not 

be sufficient heat content to meet the minimum net heating value requirements in 40 CFR 

§60.18. Therefore, it may be necessary to monitor the net heating value of the VOC vapors 

routed to the flare to ensure there is sufficient energy available to support combustion. The 

adopted rules provide the following options for demonstrating compliance with the minimum net 

heating value requirements in 40 CFR §60.18 during degassing operations: continuously monitor 

the net heating value of the gas stream routed to the flare; assume 3.4% of the net heating value 

from the VOC vapors routed to the flare and continuously monitor the supplemental fuel added 
25 

and use calculations to demonstrate sufficient net heating value of the VOC vapors routed to the 

flare; or use calculations to demonstrate sufficient net heating value of the VOC vapors routed to 

the flare. 

The adopted rules allow for the use of recirculation systems as an option for meeting the control 

requirements of the rules. The adopted rules define a recirculation system as a system that is 

vapor-tight and composed of piping, ductwork, connections, flow-inducing devices, and a 

control device. The recirculation system conducts VOC vapor from a storage tank, transport 

vessel, or marine vessel to a control device and conducts the exhaust from the outlet of the 

control device back into the same storage tank, transport vessel, or marine vessel. Currently, the 

commission is aware of two types of recirculation systems available for degassing operations 

that use condensation or absorption processes to transfer VOC from the vapor space inside the 

tank or vessel into liquid form. 

To minimize pressurization in the tank or vessel, which could cause increased emissions, the 

adopted rules require that the recirculation system not cause the pressure inside the tank or vessel 

to exceed one inch water pressure at any time during the degassing operation. The adopted rules 

will also require continuous monitoring of the tank pressure or the continuous monitoring of the 

flow rate at the inlet and outlet of the control device. To ensure that the recirculation system is 

vapor-tight during operation, the commission is requiring the recirculation system to be 

monitored for VOC leaks using the procedure in Method 21 (40 CFR Part 60, Appendix A-7) 

and to begin this monitoring within one hour after beginning any degassing operation. The 

adopted rules also require continuous monitoring of the outlet gas temperature of a condensation 

system that is part of a recirculation system to ensure that the temperature is below the 

recirculation system manufacturer’s recommended operating temperature for controlling the 

VOC vapors routed to the device. 

The commission is adopting an option to limit the VOC concentration at the outlet of the control 

device to less than 500 ppm(v)at 0% oxygen, dry basis, expressed as methane. The commission 

adopts this option to limit the VOC concentration of the control device exhaust gas as an 

equivalent or more stringent alternative to using a control device that maintains a control 

efficiency of at least 90%. The commission is adopting this option to provide affected owners or 

operators with an alternative control option that would alleviate some of the testing and 

monitoring requirements for devices that can maintain a low exhaust gas concentration. 

Clarification of Monitoring and Testing Requirements 

One of the concerns raised by stakeholders was that the existing rules do not adequately address 

the monitoring and testing requirements necessary to demonstrate compliance with this division. 

The adopted rules specifically require monitoring and testing requirements. 

The commission adopts clarifications to the procedure for taking the VOC concentration 

measurements required in this division. The adopted rules specify that the VOC concentration 

measurements required to determine if the tank or vessel can be vented to the atmosphere 

without control for the remainder of the degassing operation must be taken over a period of five 

minutes. Further, none of the measurements can exceed the thresholds established in the rules. 

This clarification is consistent with the concentration monitoring requirements in the Refinery 

Maintenance, Startup, and Shutdown (MSS) Model Permit. 
26 

The current rules for the Houston-Galveston-Brazoria area require the owner or operator to 

monitor the VOC concentration once every 12 hours for five readings after the tank or vessel is 

disconnected from the control device. This requirement was added in 2007 to address concerns 

that if liquid remains in the tank or vessel, then the VOC concentration could increase above the 

limits specified in the rules after the control device is disconnected. Stakeholders have 

commented that this requirement is unnecessary and overly burdensome. In response to these 

concerns, the commission is adopting additional options for demonstrating that the VOC 

concentration inside the tanks or vessel does not increase above the concentration limit 

established in the control requirements. Specific details regarding these additional options are 

included in the SECTION BY SECTION DISCUSSION portion of this preamble. Additionally, 

the commission is adopting rules that expand these requirements to all areas subject to this 

division. 

The commission is specifically adopting rules to require control efficiency demonstrations 

conducted in accordance with the approved test methods in §115.545 for any control device used 

to comply with the option to maintain a control efficiency of at least 90% when the device is 

being used for degassing operations. The adoption of this requirement to conduct an initial 

control efficiency demonstration is intended to be a clarification of the existing requirements and 

is not intended to impose any additional requirements on affected sources. The commission is 

also requiring the control device to be retested prior to use for degassing operations or within 60 

days after any modification that could reasonably be expected to affect the efficiency of a control 

device The commission is also requiring a periodic control efficiency demonstration to be 

conducted at least once every 60 months for a portable control device. These retesting provisions 

are necessary to demonstrate that the control device continues to meet the 90% control efficiency 

requirements after modification or if substantial time has passed since the previous 

demonstration. Additionally, it has come to the commission’s attention that many of the control 

devices used to control emissions during degassing operations are portable devices. It is not the 

commission’s intent that moving a portable control device from one tank or vessel to another 

will trigger the 60-day retesting requirement. The commission is exempting a portable thermal 

oxidizer or vapor combustor from the periodic control efficiency demonstration if the 

combustion chamber temperature is at least 1,400 degrees Fahrenheit and the flow rate of the 

VOC vapors routed to the device is limited to assure at least a 0.5 second combustion chamber 

residence time when the device is in use. 

The commission is also adopting rules to allow the use of additional test methods to demonstrate 

compliance with this division. The adopted rules will allow for the use of test methods not 

currently included in the existing rules. The adopted rules will also allow test methods currently 

available for use by affected sources in the Houston-Galveston-Brazoria area to be used by 

affected sources in all areas subject to this division. 

The commission adopts clarifications for the storage temperature used for determining the true 

vapor pressure of volatile organic liquids stored at or above ambient temperatures. The existing 

rules requires the use of actual storage temperature to determine the true vapor pressure of 

volatile organic liquids stored in an affected storage tank, transport vessel, or marine vessel. The 

commission is adopting rules to allow the actual storage temperature of an unheated tank or 

vessel to be determined using the maximum local monthly average ambient temperature as 
27 

reported by the National Weather Service. The commission is also adopting rules to allow the 

actual storage temperature of a heated tank or vessel to be determined using either the measured 

temperature or the temperature set point of the tank or vessel. 

The adopted rulemaking requires the owner or operator of a storage tank, transport vessel, or 

marine vessel subject to the requirements in this division to notify the appropriate regional office 

of upcoming degassing operations upon request by authorized representatives of the executive 

director. The commission adopts this requirement to facilitate enforcement of the rules. 

SECTION BY SECTION DISCUSSION 

In addition to the revisions to clarify the rules and provide additional flexibility, the commission 

adopts grammatical, stylistic, and various other non-substantive changes to update the rules in 

accordance with current Texas Register style and format requirements, improve readability, 

establish consistency in the rules, and conform to the standards in the Texas Legislative Council

Drafting Manual, September 2010. Such changes include appropriate and consistent use of 

acronyms, punctuation, section references, and certain terminology like that, which, shall, and 

must. References to the Dallas/Fort Worth area and the Houston/Galveston area have been 

updated to the Dallas-Fort Worth area and the Houston-Galveston-Brazoria area respectively to 

be consistent with current terminology for the region. These non-substantive changes are not 

intended to alter the existing rule requirements in any way and are not specifically discussed in 

this preamble. 

The commission also adopts changes to the rule not included at proposal. The commission 

revises any proposed references to volatile organic liquids or vapors to volatile organic

compounds. The commission changes the title of Chapter 115, Subchapter F, Division 3 from 

Degassing and Cleaning of Storage Tanks, Transport Vessels, and Marine Vessels to Degassing

of Storage Tanks, Transport Vessels, and Marine Vessels. As discussed elsewhere in this 

preamble, this change is intended to clarify the scope of the rule. In addition, the rule has been 

revised from proposal to eliminate any references to cleaning operations to further clarify the 

rule applicability. These non-substantive changes are not intended to alter the existing rule 

requirements in any way and are not specifically discussed in this preamble. 

Section 115.540, Applicability and Definitions 

The commission adopts new §115.540 that will add applicability and definitions to clarify the 

Chapter 115, Subchapter F, Division 3 rules. Adopted new §115.540 establishes consistency with 

other rules in Chapter 115 and improves the readability of the rules by first defining the units 

affected by and terms used in the subsequent requirements. 

The commission adopts new §115.540(a) to specify that the provisions in this division apply to 

degassing during, or in preparation of, cleaning of any storage tank, transport vessel, or marine 

vessel located in the Beaumont-Port Arthur (Hardin, Jefferson, and Orange Counties), DallasFort Worth (Collin, Dallas, Denton, and Tarrant Counties only), El Paso, and HoustonGalveston-Brazoria (Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, 

and Waller Counties) areas. Adopted new subsection (a) clarifies that this division applies to 

degassing any storage tank, transport vessel, or marine vessel containing volatile organic 
28 

compounds with a true vapor pressure greater than or equal to 0.5 pounds per square inch 

absolute (psia) under actual storage conditions unless specifically exempted in §115.547. 

Adopted new subsection (a) also clarifies that in this division, the operator of any storage tank, 

transport vessel, or marine vessel refers to the regulated entity performing or outsourcing the 

degassing operation. Adopted new subsection (a) indicates that this division applies to any 

storage tank, transport vessel, or marine vessel in the Beaumont-Port Arthur and HoustonGalveston-Brazoria areas. Adopted new subsection (a) also indicates that this division applies to 

any storage tank or transport vessel in the Dallas-Fort Worth and El Paso areas. 

Adopted new §115.540(b) indicates that unless the context clearly indicates otherwise or unless 

specifically defined in the Texas Clean Air Act (Texas Health and Safety Code, Chapter 382), in 

30 TAC §§3.2, 101.1, or 115.10 the terms used in this division have the meanings commonly 

used in the field of air pollution control. Adopted new subsection (b) also indicates that in 

addition, the following meanings apply in this division unless the context clearly indicates 

otherwise. 

Adopted new §115.540(b)(1) defines Cleaning as the process of washing or rinsing a storage 

tank, transport vessel, or marine vessel, or removing sludge or rinsing liquid from a storage tank, 

transport vessel, or marine vessel. As discussed in the RESPONSE TO COMMENTS section of 

this preamble, the word vapor was removed from the proposed definition of Cleaning to help 

clarify the processes intended to be subject to this rule. The commission is revising this 

definition to help clarify the rule applicability. 

Adopted new §115.540(b)(2) defines Degassing as the process of removing VOC vapor from a 

storage tank, transport vessel, or marine vessel during, or in preparation of, cleaning. As 

discussed in the RESPONSE TO COMMENTS section of this preamble, the definition of 

Degassing has been revised from proposal to clarify that this term applies to activities that occur 

during, or in preparation of, cleaning. The commission is revising this definition to further clarify 

the rule applicability. 

As discussed in the RESPONSE TO COMMENTS section of this preamble, the commission is 

adopting new §115.540(b)(3) to define a Drain-dry floating roof tank as a floating roof tank 

designed to drain its entire contents completely to a sump in a manner that leaves no freestanding liquid in the tank or the sump. The only stock liquid available for evaporation in a 

drain-dry floating roof tank is that which clings to the tank bottom and other wetted surfaces 

under the floating roof. This definition comes from American Petroleum Institute (API) 

Technical Report 2568, Evaporative Loss from the Cleaning of Storage Tanks (November 2007). 

Adopted new §115.540(b)(4), originally proposed as §115.540(b)(3), defines Recirculation

system as a system that is vapor-tight and composed of piping, ductwork, connections, flow 

inducing devices, and a control device. Adopted new paragraph (4) states that the recirculation 

system conducts VOC vapor from a storage tank, transport vessel, or marine vessel to a control 

device and conducts the exhaust from the outlet of the control device back into the same storage 

tank, transport vessel, or marine vessel. Adopted new paragraph (4) also indicates that the 

recirculation system does not include the storage tank, transport vessel, or marine vessel that is 

being degassed. The commission is adding this definition to fully describe the type of system 

being adopted as a new option to control VOC vapors during degassing operations. 
29 

Adopted new §115.540(b)(5), originally proposed as §115.540(b)(4), defines Storage capacity as 

the volume of a storage tank as determined by multiplying the internal cross-sectional area of the 

tank by the average internal height of the tank shell or the volume of a transport vessel or marine 

vessel as determined by the manufacturer’s original design capacity. The definition is intended to 

account for sloped tank floors and sumps by relying on the average internal height of the tank 

shell to determine the maximum amount of liquid the tank can hold if filled to the top of the tank 

shell with inflow and outflow pipes closed off and any floating roof absent. The average internal 

height may be conservatively measured as the maximum height from the bottom of a sump to the 

top of the tank shell. Use of this measurement will result in an overestimate of the volume of a 

tank with a sloped floor. The existing rule uses several different terms, including nominal storage 

capacity, to denote the tanks and vessels that are subject to these requirements. The commission 

adopts this definition and uses the term consistently throughout this rulemaking. The adopted 

change is not intended to alter any existing rule requirements or to cause any additional sources 

to be subject to the existing rule requirements. 

Adopted new §115.540(b)(6), originally proposed as §115.540(b)(5), defines Storage tank as a 

stationary vessel, reservoir, or container used to store VOC. This definition does not include 

components that are not directly involved in the containment of liquids or vapors, subsurface 

caverns or porous rock reservoirs, or process tanks or vessels. 

Adopted new §115.540(b)(7), originally proposed as §115.540(b)(6), defines Vapor-tight as a 

condition that exists when no component of a system has a leak greater than 500 parts per 

million expressed as methane measured using Method 21 (40 CFR Part 60, Appendix A-7). The 

commission is adopting this definition to help clarify existing requirements that use this term. 

Although there are no additional monitoring requirements included in the adopted rule to 

demonstrate compliance with vapor-tight requirements, a notice of violation could be issued to 

the owner or operator of the tank or vessel if an authorized representative of the executive 

director, the EPA, or any local air pollution control agency with jurisdiction determined the 

vapor-tight condition was not maintained. 

Section 115.541, Emission Specifications 

The commission adopts the repeal of existing §115.541 in order to reformat and clarify the 

emission specifications in this division. 

The adopted repeal is not intended to remove any of the existing emission specifications. The 

existing requirements in this section are either being incorporated into the adopted new §115.541 

or the adopted new control requirements in §115.542. 

The commission adopts new §115.541 to include the emission specifications for the degassing of 

storage tanks, transport vessels, or marine vessels. 

Adopted new §115.541(a) requires all VOC vapors from a storage tank, transport vessel, or 

marine vessel subject to this division to be routed to a control device in accordance with the 

control requirements in §115.542 during degassing operations. Adopted new subsection (a) 

incorporates the existing emission specifications in §115.541(a)(1)(A) and (2)(A), and (b)(2) and 
30 

does not impose a new requirement on affected sources. In response to comments, subsection (a) 

has been revised from proposal to specify that this requirement does not apply if the measured 

VOC concentration is less than 34,000 ppmv, expressed as methane or 50% of the lower 

explosive limit (LEL). The adopted change is intended to clarify the rule applicability. 

Adopted new §115.541(b) prohibits the intentional bypassing of a control device used to comply 

with the requirements in this division. Adopted new subsection (b) also requires any visible VOC 

leak originating from the control device, or other associated product recovery device, to be 

repaired as soon as practical. Adopted new subsection (b) incorporates the existing emission 

specifications in §115.541(a)(1)(D) and (2)(D), and (b)(4) and does not impose a new 

requirement on affected sources. 

Adopted new §115.541(c) prohibits avoidable liquid or gaseous leaks, as detected by sight or 

sound, from the degassing operations. Adopted new subsection (c) incorporates the existing 

emission specifications in §115.541(a)(1)(C) and (2)(C), and (b)(3) and does not impose a new 

requirement on affected sources. 

Adopted new §115.541(d) requires a transport vessel to be kept vapor-tight at all times until the 

VOC vapors are routed to a control device. Adopted new subsection (d) incorporates the 

existing emission specifications in §115.541(a)(2)(E) and does not impose a new requirement on 

affected sources. 

Adopted new §115.541(e) has been reformatted from proposal; however, these changes are nonsubstantive and only intended to improve the readability of the rule. Adopted new 

§115.541(e)(1) requires a marine vessel to have all cargo tank closures properly secured or 

maintain a negative pressure within the vessel when a closure is opened. Adopted new 

§115.541(e)(1) requires a marine vessel to have all pressure or vacuum relief valves operating 

within certified limits, as specified by classification society or flag state, until the VOC vapors 

are routed to a control device. Adopted new subsection (e) incorporates the existing emission 

specifications in §115.541(b)(5) and does not impose a new requirement on affected sources. 

As discussed elsewhere in this preamble, in response to comments §115.541(f) has been revised 

from proposal to provide some exceptions to the requirements based on tank design and the 

contents of the material being stored in the tank. As proposed, subsection (f) would have 

required all VOC vapors from a floating roof storage tank to be routed to a control device 

immediately but no later than 24 hours after the tank has been emptied to the extent practical or 

the drain pump loses suction. Adopted new §115.541(f)(1) requires all VOC vapors from a 

floating roof storage tank that is not a drain-dry floating roof storage tank to be routed to a 

control device as soon as practical but no later than 24 hours after the tank has been emptied to 

the extent practical or the drain pump loses suction for a floating roof storage tank containing 

VOC liquids with a true vapor pressure greater than or equal to 1.5 psia under actual storage 

conditions. Adopted new §115.541(f)(2) requires all VOC vapors from a floating roof storage 

tank that is not a drain-dry floating roof storage tank must be routed to a control device as soon 

as practical but no later than 72 hours after the tank has been emptied to the extent practical or 

the drain pump loses suction for a floating roof storage tank containing VOC liquids with a true 

vapor pressure less than 1.5 psia under actual storage conditions. Adopted new §115.541(f)(3), 

which provides an alternative to new subsection (f)(1) and (2), requires that all VOC vapors from 
31 

a floating roof storage tank that is not a drain-dry floating roof storage tank must be routed to a 

control device as soon as practical but no later than the time limit specified in a permit issued 

under 30 TAC Chapter 116 up to a maximum of 72 hours after the tank has been emptied to the 

extent practical or the drain pump losses suction. The commission adopts these new requirements 

to clarify when the rules in this division begin to apply and to minimize standing idle losses from 

floating roof storage tanks. 

Section 115.542, Control Requirements 

The commission is adopting the repeal of existing §115.542 in order to reformat and clarify the 

emission specifications in this division. The adopted repeal is not intended to remove any of the 

existing emission specifications. The existing requirements in this section are being incorporated 

into the proposed new §115.542. 

The commission adopts new §115.542 to include the control requirements for the degassing of 

storage tanks, transport vessels, or marine vessels. 

Adopted new §115.542(a) requires a control device used to comply with the emission 

specifications in §115.541 to meet one of the following conditions at all times when VOC vapors 

are routed to the device. The commission is including several equivalent options to limit VOC 

emissions from degassing operations that occur during, or in preparation of, cleaning an affected 

storage tank, transport vessel, or marine vessel. 

Adopted new §115.542(a)(1) includes the same requirement in existing §115.541(a)(1)(B) and 

(2)(B), and (b)(2) for a control device to maintain a control efficiency of at least 90%. Adopted 

new paragraph (1) also clarifies the commission’s intent that any control device used to comply 

with this division must be operated in a manner consistent with how the device was operated 

during the control efficiency demonstration required in §115.544(c). 

Adopted new §115.542(a)(2) requires a flare that is used to comply with the requirements in this 

division to be designed and operated in accordance with 40 CFR §60.18(b) - (f) (as amended 

through December 22, 2008 (73 FR 78209)) and to be lit at all times when VOC vapors are 

routed to the flare. As discussed elsewhere in this preamble, although 40 CFR §60.18 requires 

the pilot to be lit at all times and requires monitoring of the flare pilot flame, the commission is 

also specifically requiring the flare flame to be lit to clarify that the intent of the rule is for both 

the flare flame and the pilot to be lit at all times when VOC vapors are routed to the device. 

Adopted new §115.542(a)(2) was revised from proposal to specifically incorporate the version of 

40 CFR §60.18(b) - (f) (as amended through December 22, 2008 (73 FR 78209)). 

Adopted new §115.542(a)(3) allows a recirculation system to be used to comply with the 

requirements in this division provided it does not cause the pressure inside the tank or vessel to 

increase any more than one inch water pressure at any time during degassing operation. 

Adopted new §115.542(a)(4) allows a control device used to comply with the requirements of 

this division provided that the VOC concentration at the outlet of the control device is less than 

500 ppm(v)at 0% oxygen, dry basis, expressed as methane. 
32 

Adopted new §115.542(b) requires all VOC vapors to be routed to a control device until the 

VOC concentration is less than 34,000 ppmv, expressed as methane or less than 50% of the LEL. 

In response to comments, all proposed requirements that the percent LEL be expressed as 

methane have been removed from the adopted rule. After one of the conditions has been 

satisfied, the tank or vessel may be vented to the atmosphere without control for the remainder of 

the degassing operation, except as specified in §115.544(b)(4). The commission is expanding the 

requirement in §115.544(b)(4) to all applicable areas subject to the rules. The reference to 

§115.544(b)(4) is necessary to clarify that the additional monitoring required by that section still 

applies. For sources in the Houston-Galveston-Brazoria area, adopted new subsection (b) 

contains the same requirements as existing §115.542(a)(6) and (b)(5) and compliance with the 

original requirement was required by January 1, 2009. 

The commission is repealing the options in existing §115.542(a)(5) and (b)(4) for sources in the 

Beaumont-Port Arthur, Dallas-Fort Worth, or El Paso areas. The commission is repealing the 

existing option for the tank or vessel to be vented to the atmosphere without control for the 

remainder of the degassing operation once the true vapor pressure inside the vessel has been 

reduced to less than 0.5 psia since this measurement is more appropriately referenced in terms of 

a VOC vapor concentration rather than a liquid characteristic. The commission is also repealing 

the existing option for the tank or vessel to be vented to the atmosphere without control once a 

turnover of at least four vapor space volumes, or four turnovers of the vapor space under a 

floating roof, has occurred. If the tank or vessel is drained dry and if the flow of displacement 

gases is measured properly, four turnovers would generally be sufficient to reduce VOC 

concentrations to less than 34,000 ppmv. However, if liquids remain in the bottom of the tank or 

vessel, as commonly occurs due to irregularities in the vessel surface, the remaining liquid would 

continue to be a source of VOC emissions after the four turnover criterion has been satisfied. 

In addition, the commission is providing sources in the Beaumont-Port Arthur, Dallas-Fort 

Worth, or El Paso areas with the option for the tank or vessel to be vented to the atmosphere 

without control for the remainder of the degassing operation once the VOC concentration before 

the inlet to the control device is less than 50% of the LEL. The adopted control requirements 

allow the tank or vessel to be vented to the atmosphere without control once the VOC 

concentration reaches 34,000 ppmv, expressed as methane or 50% of the LEL. The adopted new 

option for the tank or vessel to be vented to the atmosphere without control once the VOC 

concentration is less than 50% of the LEL as stringent than the existing option for the tank or 

vessel to be vented to the atmosphere without control once the VOC concentration reaches 

34,000 ppmv, expressed as methane. Existing §115.542(b)(4) uses 20% of the LEL as one of the 

options for determining when marine vessels in the Beaumont-Port Arthur area may be vented to 

the atmosphere without control. Because the LEL criterion is an option to allow flexibility in 

measurement methods and because the existing 34,000 ppm(v) concentration limit is the least 

stringent option, the adopted option to allow 50% of the LEL instead of 20% of LEL in adopted 

new subsection (b) will not allow an increase in VOC emissions over those allowed under 

existing §115.542(b)(4). 

Adopted new §115.542(c) requires degassing equipment to be designed and operated to prevent 

avoidable liquid or gaseous VOC leaks. Adopted new subsection (c) contains the same 

requirement in existing §115.542(a)(4) and (b)(3). 
33 

Adopted new §115.542(d) requires that when degassing is effected through the hatches or 

manways of a storage tank, all lines must be equipped with fittings that make vapor-tight 

connections. Adopted new subsection (d) contains portions of the requirement in existing 

§115.542(a)(3). Proposed new subsection (d) would have also required all lines to be closed 

when disconnected or equipped to discharge residual VOC in the line into a closed recovery or 

disposal system after degassing is complete. However, in response to comments the commission 

is deleting this requirement because the VOC concentration in the lines will already be less than 

the VOC concentration that is required to be routed to a control device and therefore will not 

need to be controlled to demonstrate compliance with the requirements in this division. 

Adopted new §115.542(e) requires that when degassing is effected through the hatches of a 

transport vessel with a loading arm equipped with a vapor collection adapter, a pneumatic, 

hydraulic, or other mechanical means must be provided to force a vapor-tight seal between the 

adapter and the hatch. Adopted new subsection (e) also requires a means to be provided to 

minimize liquid drainage from the degassing equipment when it is removed from the hatch or to 

accomplish drainage before such removal. Adopted new subsection (e) contains the same 

requirement in existing §115.542(a)(2). 

Adopted new §115.542(f) requires that when degassing is effected through the hatches of a 

marine vessel with a loading arm equipped with a vapor collection adapter, then pneumatic, 

hydraulic, or other mechanical means must be provided to force a vapor-tight seal between the 

adapter and the hatch, or a negative pressure inside the cargo tank must be maintained. Adopted 

new subsection (f) also requires a means to be provided to minimize liquid drainage from the 

degassing equipment when it is removed from the hatch or to accomplish drainage before such 

removal. Adopted new subsection (f) contains the same requirement in existing §115.542(b)(2). 

Section 115.543, Alternate Control Requirements 

The commission adopts non-substantive revisions to §115.543 necessary to comply with current 

rule formatting standards without changes from proposal. 

Section 115.544, Inspection, Monitoring, and Testing Requirements 

The commission is changing the title of §115.444 from Inspection Requirements to Inspection,

Monitoring, and Testing Requirements to reflect the adopted changes to the content of this 

section. 

The commission adopts subsection (a) to specify the inspection requirements that apply during 

the degassing of any storage tank, transport vessel, or marine vessel subject to this division. 

The commission is amending §115.544(a)(1) with non-substantive changes necessary to comply 

with current rule formatting standards. Amended paragraph (1) requires inspection for visible 

liquid leaks, visible fumes, or significant odors resulting from VOC transfer operations that are 

conducted during each degassing operation. 

The commission is amending §115.544(a)(2) with non-substantive changes necessary to comply 

with current rule formatting standards. Amended paragraph (2) requires degassing through the 
34 

affected transfer lines to be discontinued when a leak is observed that cannot be repaired within a 

reasonable length of time. The commission is removing the sentence in existing paragraph (2) 

that indicates that the intentional bypassing of a vapor control device during degassing is 

prohibited. The commission is removing this superfluous sentence because the same requirement 

is already more appropriately included in the emission specifications in §115.542. 

Adopted §115.544(b) specifies the monitoring requirements that apply during the degassing of 

any storage tank, transport vessel, or marine vessel subject to this division. Adopted subsection 

(b) also indicates that monitoring at least once every 15 minutes is sufficient to demonstrate 

compliance with the continuous monitoring requirements in this subsection. 

Adopted §115.544(b)(1) requires any monitoring device used to comply with the requirements in 

this subsection to be installed, calibrated, maintained, and operated according to the 

manufacturer’s instructions. The commission is adopting paragraph (1) to clarify the 

expectations associated with monitoring equipment used to comply with the requirements in this 

division. 

Adopted §115.544(b)(2) requires the owner or operator to monitor any operational parameters 

necessary to demonstrate the proper functioning of a control device used to comply with the 

requirements in this division at all times when VOC vapors are routed to the device. Adopted 

paragraph (2) contains the same monitoring requirements in existing §115.546(2) and also 

includes the applicable monitoring requirements associated with the adopted new control 

options. 

Adopted §115.544(b)(2)(A) requires the owner or operator to continuously monitor the exhaust 

gas VOC concentration of any carbon adsorption system that regenerates the carbon bed directly 

to determine breakthrough. Alternatively, adopted subparagraph (A) requires the owner or 

operator to periodically monitor the exhaust gas VOC determine breakthrough and switch the 

exhaust gas flow to fresh carbon for any carbon adsorption system that does not regenerate the 

carbon bed directly, as specified by 40 CFR §61.354(d) (as amended through October 17, 2000 

(65 FR 62160)), except that any monitoring must be conducted at intervals no greater than 20% 

of the design carbon replacement interval. Adopted §115.544(b)(2)(A) was revised from 

proposal to specify the applicable version of 40 CFR §60.354(d). Adopted subparagraph (A) 

contains the requirements in existing §115.546(2)(C). In addition, adopted subparagraph (A) 

clarifies that the owner or operator must switch the exhaust gas flow to fresh carbon for any 

carbon adsorption system that does not regenerate the carbon bed directly and clarifies that any 

monitoring must be conducted at intervals no greater than 20% of the design carbon replacement 

interval. The commission is adopting these additional requirements to account for the high flow 

rate conditions encountered during degassing operations. In addition, adopted subparagraph (A) 

specifies that for the purpose of this division, breakthrough is defined as a measured VOC 

concentration exceeding 100 ppmv, expressed as methane above background. The adopted 

threshold is based on the requirements in the Refinery MSS Model Permit. 

Adopted §115.544(b)(2)(B) requires the owner or operator to continuously monitor the inlet and 

outlet gas temperature of a catalytic incinerator. Adopted subparagraph (B) contains the same 

requirements in existing §115.546(2)(B). 
35 

Adopted §115.544(b)(2)(C) requires the owner or operator to continuously monitor the outlet gas 

temperature of a condensation system to ensure that the temperature is below the manufacturer’s 

recommended operating temperature for controlling the VOC vapors routed to the device. The 

adopted monitoring and associated recordkeeping requirement also apply if the condensation 

system is part of a recirculation system. 

Adopted §115.544(b)(2)(D) requires the owner or operator to continuously monitor the exhaust 

gas temperature immediately downstream of a direct-flame incinerator. Adopted subparagraph 

(B) contains the same requirements in existing §115.546(2)(C). 

Adopted §115.544(b)(2)(E) requires the owner or operator to comply with one of the monitoring 

requirements in clauses (i) - (iv) if a flare is used to comply with the requirements in this 

division. In response to comments, subparagraph (E) was revised to clarify that the purpose of 

these monitoring requirements is to demonstrate compliance with the requirements in 40 CFR 

§60.18. In response to comments, clauses (i) - (iii) were amended from proposal to refer the gas

stream routed to the flare and not just the VOC vapors routed to the flare. Adopted clause (i) 

requires the owner or operator to continuously monitor the net heating value of the gas stream 

routed to the flare. In response to comments, changes were made to the proposed language in 

clause (ii). As proposed, clause (ii) would have required the owner or operator to assume zero net 

heating value contribution from the VOC vapors routed to the flare. Adopted clause (ii) requires 

the owner or operator to continuously monitor the total volume of supplemental fuel added to the 

gas stream routed to the flare and continuously maintain sufficient supplemental fuel to meet the 

minimum net heating value requirements in 40 CFR §60.18 assuming that the net heating value 

of the degassed VOC vapor is equivalent to a level corresponding to 50% of the LEL. New 

clause (ii) also allows the owner or operator to estimate the flow rate of the VOC vapors from the 

tank or vessel if the flow rate is not monitored. Proposed clause (ii) would have required the 

owner or operator to continuously monitor the total volume of supplemental fuel added to the 

VOC vapors routed to the flare and assume the net heating value of the VOC vapors routed to the 

flare is zero. Adopted clause (iii) requires the owner or operator to use calculations to 

demonstrate that for the material stored in the tank or vessel the net heating value of the gas 

stream routed to the flare cannot drop below the minimum net heating value requirements in 40 

CFR §60.18 until the concentration of VOC in the vapors being routed to the flare is less than the 

concentration limits in §115.542(b). In response to comments, a new clause (iv) is added to allow 

for the monitoring of hydrogen content instead of net heating value for non-assisted flares 

electing to comply with 40 CFR §60.18(c)(3)(i). 

Adopted §115.544(b)(2)(F) requires the owner or operator to use one of the following methods 

to monitor the exhaust gas VOC concentration for any control device used to comply with the 

option in §115.542(a)(4) to limit exhaust concentration. Proposed subparagraph (F) would have 

required monitoring the exhaust gas VOC concentration at least once per hour. However, in 

response to comments, adopted subparagraph (F) requires owner or operator to perform a single 

one-hour test to demonstrate the concentration of the VOC is below the concentration limit in 

§115.542(a)(4). Adopted subparagraph (F) also specifies the test must begin within one hour 

after the start of the degassing operation. The beginning of the degassing operation is when peak 

VOC concentration to the control device is expected. If the control device demonstrates that the 

VOC concentration is less than the limit during this initial one-hour test, then further testing 

during that same degassing event should not be necessary. In addition, as proposed, 
36 

subparagraph (F) would have required the owner or operator of any internal combustion engine 

used as a control device to monitor the exhaust gas VOC concentration hourly for the entire 

duration of the degassing event. As discussed in the RESPONSE TO COMMENTS portion of 

this preamble, the commission is not adopting this requirement for engines and has instead 

adopted a subparagraph (I) that specifies monitoring exhaust gas oxygen monitoring as the 

appropriate parameter monitoring for internal combustion engines. 

Adopted subparagraph (F) also specifies that the VOC concentration must be determined using 

the methods listed in adopted clauses (i) and (ii). Adopted clause (i) requires the VOC 

concentration to be determined by using the integrated bag sampling procedure in Method 18 (40 

CFR Part 60, Appendix A) §§8.2.1.1 - 8.2.1.4 and a total hydrocarbon analyzer that meets 

instrument and calibration specifications in Method 21. As an alternative to clause (i), adopted 

clause (ii) requires the VOC concentration to be determined by continuously monitoring the 

exhaust gas VOC concentration using Method 25A (40 CFR Part 60, Appendix A). 

Adopted §115.544(b)(2)(G) requires the owner or operator to continuously monitor the 

combustion chamber temperature of a thermal oxidizer or vapor combustor. Adopted 

subparagraph (G) also requires the owner or operator to continuously monitor the gas flow rate 

into the thermal oxidizer or vapor combustor to determine the combustion chamber residence 

time if necessary to demonstrate compliance with §115.544(c)(3). In response to comments, 

adopted subparagraph (G) was revised from proposal to apply the requirements for thermal 

oxidizers to both thermal oxidizers and vapor combustors. 

Adopted §115.544(b)(2)(H) requires the owner or operator to continuously monitor the pressure 

inside the tank or vessel or continuously monitor the gas flow rate at the inlet and outlet of the 

control device if a recirculation system is used to comply with this division. Adopted 

subparagraph (H) also requires the owner or operator to monitor for VOC leaks using the 

procedure in Method 21 and begin this monitoring within one hour after beginning any degassing 

operation. For the purposes of this requirement, the adopted rule defines a leak as a screening 

concentration greater than 500 ppm(v) above background as methane for all components. 

In response to comments, the commission is adopting §115.544(b)(2)(I) specifying that for an 

internal combustion engine, the owner or operator shall continuously monitor the engine exhaust 

gas oxygen content throughout the degassing operation as an indicator of the proper operation of 

the engine. 

In response to comments, the commission is adopting §115.544(b)(2)(J) specifying that for a 

control device not listed, the owner or operator shall continuously monitor one or more 

operational parameters sufficient to demonstrate proper functioning of the device to design 

specification. The commission is adopting this provision to ensure the operational parameter 

monitoring of any device used to comply with the requirements in this division. 

Adopted §115.544(b)(3) requires the owner or operator to monitor the VOC concentration to 

demonstrate compliance with the VOC concentration or percent LEL limits in §115.542(b) and 

determine if the storage tank, transport vessel, or marine vessel can be vented to the atmosphere 

without control for the remainder of the degassing operation, except as specified in paragraph 

(4). Adopted §115.544(b)(3)(A), proposed as §115.544(b)(3), requires the VOC concentration to 
37 

be monitored once per minute for at least five minutes, and all measurements must be less than 

the VOC concentration limits in §115.542(b). The commission is adopting this language to 

clarify the monitoring procedure that should be used to determine the VOC concentration prior to 

venting the tank or vessel to the atmosphere without control for the remainder of the degassing 

operation. The commission is adopting this procedure to increase consistency between this rule 

and the Refinery MSS Model Permit. In response to comments, the commission is also adopting 

§115.544(b)(3)(B) to allow the VOC concentration to be monitored over a five-minute period 

using the integrated bag sampling procedure in Method 18 (40 CFR Part 60, Appendix A) 

§§8.2.1.1 - 8.2.1.4 and the integrated measurement must be less than the VOC concentration 

limits in §115.542(b). The commission is adopting this alternative monitoring option as an 

equivalent procedure to the monitoring option in adopted §115.544(b)(3)(A). As adopted, 

§115.544(b)(3)(B) would allow the use of integrated bag sampling for determining the VOC 

concentration for the purposes of either the 34,000 ppmv, expressed as methane or the 50% of 

the LEL limit. 

Adopted §115.544(b)(4) requires the owner or operator of any storage tank, transport vessel, or 

marine vessel to comply with one of the conditions in this paragraph after demonstrating 

compliance with the applicable VOC concentration or percent LEL limits in §115.542(b) or (c) 

in accordance with paragraph (3). The existing rule requires affected owners or operators to 

monitor a tank or vessel for 48 hours after reaching the applicable VOC concentration or percent 

LEL limits. The commission is expanding this option to all areas affected by this rulemaking as 

well as providing additional options. 

Adopted §115.544(b)(4)(A) allows the VOC concentration inside the tank or vessel to be 

monitored once every 12 hours while venting to the atmosphere without control until five 

consecutive measurements collected at 12-hour intervals are measured to be less than 34,000 

ppm(v)or less than 50% of the LEL. The VOC concentration measurement required by paragraph 

(3) may be considered the first of these five consecutive measurements. Adopted clause (i) 

specifies that if venting to the atmosphere without control has been suspended for more than four 

hours, the VOC concentration inside the tank or vessel must be measured upon restart of the 

degassing operation. For consistency, adopted clause (i) was revised from proposal to read 

venting to the atmosphere without control instead of uncontrolled venting to the atmosphere.

Adopted clause (ii) specifies that if any of the VOC concentration measurements equal or exceed 

34,000 ppmv, expressed as methane or 50% of the LEL, the tank or vessel must be routed to the 

control device until the VOC concentration is below 34,000 ppmv, expressed as methane or less 

than 50% of the LEL as determined by subsection (b)(3). Adopted subparagraph (A) contains the 

existing requirements in §115.542(a)(6) and (b)(5) for the Houston-Galveston-Brazoria area and 

applies this same requirement to all affected areas. In response to comments, the commission is 

also adopting clause (iii) to specify that if the measured VOC concentration is less than 6,800 

ppmv, expressed as methane or 10% of the LEL then no further VOC concentration 

measurements are required. The commission is adopting this option based on the premise that 

once the VOC concentration inside the tank or vessel is less than 1/5 of the standard it will not be 

possible for the VOC concentration to rise above 34,000 ppmv, expressed as methane or 50% of 

the LEL. 

Adopted §115.544(b)(4)(B) allows the storage tank, transport vessel, or marine vessel to be 

vented to the atmosphere without control for the remainder of the degassing operation with no 
38 

further VOC measurements if the VOC concentration inside the tank or vessel is less than 6,800 

ppmv, expressed as methane or 10% of the LEL before the owner or operator stops routing the 

VOC vapors to a control device in accordance with §115.541 and §115.542. Proposed 

subparagraph (B) would have required the VOC concentration inside the tank or vessel to be less 

than 1% of the LEL before the owner or operator stops routing the VOC vapors to a control 

device in accordance with §115.541 and §115.542. However, in response to comments, the 

commission is adopting a threshold of 6,800 ppmv, expressed as methane or 10% of the LEL, 

based on the premise that once the VOC concentration inside the tank or vessel is less than 1/5 of 

the standard it will not be possible for the VOC concentration to rise above 34,000 ppmv, 

expressed as methane or 50% of the LEL within the first 12 hours after disconnecting the control 

device. 

The commission is not adopting the option proposed in §115.544(b)(4)(C) that would have 

allowed the owner or operator to use the procedure in this subparagraph to demonstrate that the 

VOC concentration inside the tank or vessel will not increase above the applicable concentration 

limit in §115.542(b) or (c) before venting the tank or vessel to the atmosphere for the remainder 

of the degassing operation. As discussed in the RESPONSE TO COMMENTS section of this 

preamble, the commission is not adopting this proposed option because this proposed procedure 

may not guarantee that the VOC concentration will not rise above 34,000 ppmv, expressed as 

methane. 

In response to comments, the commission is adopting §115.544(b)(5) specifying that minor 

modifications to the monitoring methods may be approved by the executive director and that 

monitoring methods other than those specified in this subsection may be used if approved by the 

executive director and validated by 40 CFR Part 63, Appendix A, Method 301. The commission 

is adopting this provision to provide additional flexibility to affected owners or operators. 

Also, in response to comments, the commission is adopting §115.544(b)(6) to clarify that the 

sampling location for performing the monitoring required by §115.544(b)(3) may be 

immediately before the control device, in the transfer line from the tank or vessel to the control 

device, or in the vapor space of the tank or vessel provided it is representative of the 

concentration of VOC entering the control device. 

The commission adopts §115.544(c) to specify the testing requirements that apply to the owner 

or operator of any storage tank, transport vessel, or marine vessel subject to this division if a 

control device is used to comply with the emission specifications in §115.541. 

Adopted §115.544(c)(1) requires an initial control efficiency demonstration to be conducted in 

accordance with the approved test methods in §115.545 for a control device used to comply with 

the requirements in §115.542(a)(1). Proposed paragraph (1) would have required the device to be 

retested within 60 days after any modification that could reasonably be expected to affect the 

efficiency of a control device. However, in response to comments, adopted paragraph (1) 

requires the device to be retested after any modification that could reasonably be expected to 

decrease the efficiency of a control device within 60 days after the modification or before being 

used to comply with the requirements in §115.542(a)(1), whichever is longer. The commission is 

clarifying that the retest is only required if the modification would decrease the control efficiency 

of the device. The commission is also providing additional time to conduct the required retesting 
39 

for control devices that are not consistently used to comply with the requirements in 

§115.542(a)(1). 

Adopted §115.544(c)(2) requires a periodic control efficiency demonstration to be conducted at 

least once every 60 months in accordance with the approved test methods in §115.545 for a 

portable control device used to comply with the requirements in §115.542(a)(1). 

Adopted §115.544(c)(3) exempts a portable thermal oxidizer or vapor combustor used to comply 

with the requirements in §115.542(a)(1) from the periodic control efficiency demonstration in 

paragraph (2) if the combustion chamber temperature is at least 1,400 degrees Fahrenheit and the 

flow rate of the VOC vapors routed to the device is limited to assure at least a 0.5 second 

residence time all times when the device is in use. In response to comments, adopted paragraph 

(3) is revised from proposal to apply the requirements proposed for thermal oxidizers to both 

thermal oxidizers and vapor combustors. 

Section 115.545, Approved Test Methods 

The commission adopts the repeal of existing §115.545 in order to reformat and clarify the 

approved test methods in this division. The existing requirements in this section are being 

incorporated into adopted new §115.545. 

The commission adopts new §115.545 to indicate that compliance with the requirements in this 

division must be determined by applying one or more of the following test methods or 

procedures, as appropriate. Adopted new §115.545 amends the existing language in §115.545 to 

improve consistency with other rules in Chapter 115 and to more clearly indicate that the test 

methods listed in this section must be used to demonstrate compliance with all the requirements 

in this division not just the requirements in §115.541 and §115.542. 

Adopted new §115.545(1) requires the use of Methods 1 - 4 (40 CFR Part 60, Appendix A) for 

determining flow rates. Adopted new paragraph (1) contains the same requirement in existing 

paragraph (1) with non-substantive changes necessary to comply with current rule formatting 

standards. 

Adopted new §115.545(2) allows for the use Methods 3, 3A, or 3B (40 CFR Part 60, Appendix 

A) to determine exhaust gas oxygen concentration for making any oxygen corrections necessary 

for §115.541(a)(4). 

Adopted new §115.545(3) allows the use of Method 18 (40 CFR Part 60, Appendix A) for 

determining gaseous organic compound emissions by gas chromatography. Adopted new 

paragraph (3) incorporates the requirement in existing paragraph (2) with non-substantive 

changes necessary to comply with current rule formatting standards. Adopted new subparagraph 

(A) requires only one bag sample to be collected for each concentration measurement if Method 

18 is used to demonstrate compliance with the VOC concentration monitoring requirements in 

§115.542(b) and §115.544(b)(4). Adopted new subparagraph (A) contains same requirement in 

existing paragraph (11)(B) for use in the Houston-Galveston-Brazoria area. The adopted rule 

allows only one bag sample to be collected for each concentration measurement if Method 18 is 

used for demonstrating compliance with the VOC concentration monitoring requirements in all 
40 

areas affected by the rule. Adopted new subparagraph (B) requires the VOC concentration to be 

determined by using the integrated bag sampling procedure in Method 18, §§8.2.1.1 - 8.2.1.4 if 

Method 18 is used to demonstrate compliance with the VOC concentration monitoring 

requirements in §115.544(b)(2)(F) for an internal combustion engine or any control device used 

to comply with the option in §115.542(a)(4) to limit exhaust concentration. Adopted new 

subparagraph (B) was revised from proposal to remove the reference to the hourly VOC 

concentration measurements since this requirement was amended in response to comments. 

Adopted new §115.545(4) allows for the use Method 19 (40 CFR Part 60, Appendix A) for 

determining exhaust gas flow rates on combustion control devices in lieu of using Methods 1 - 4. 

Adopted new §115.545(5) allows Method 21 (40 CFR Part 60, Appendix A-7) to be used for 

determining VOC leaks. This portion of adopted new paragraph (5) contains the same 

requirement in existing paragraph (6). Adopted new paragraph (5) also allows an instrument 

meeting the specifications and calibration requirements in Method 21 to be used for 

demonstrating compliance with the VOC concentration monitoring requirements in §115.542(b) 

and §115.544(b)(3) and (4) with the provision that the instrument response factor criteria in §8.1 

of Method 21 may be determined using the average composition of the liquid in the tank rather 

than for each individual liquid. This portion of adopted new paragraph (5) contains the same 

requirement in existing paragraph (11)(A) for use in the Houston-Galveston-Brazoria area. The 

commission is allowing the use of an instrument meeting the specifications and calibration 

requirements in Method 21 for demonstrating compliance with the VOC concentration 

monitoring requirements in all areas affected by the rule. 

Adopted new §115.545(6) allows Method 25 (40 CFR Part 60, Appendix A) to be used for 

determining total gaseous non-methane organic emissions as carbon. Adopted new paragraph (6) 

contains the same requirement in existing paragraph (3). 

Adopted new §115.545(7) allows Methods 25A or 25B (40 CFR Part 60, Appendix A) to be used 

for determining total gaseous organic concentrations using flame ionization or non-dispersive 

infrared analysis. Adopted new paragraph (7) contains the same requirement in existing 

paragraph (4). 

Adopted new §115.545(8) allows Method 27 (40 CFR Part 60, Appendix A) to be used for 

determining tank-truck leaks. Adopted new paragraph (8) contains the same requirement in 

existing paragraph (8). 

Adopted new §115.545(9) allows for the use of a portable oxygen analyzer that is calibrated, 

maintained, and operated according to the manufacturer’s instructions to determine exhaust gas 

oxygen concentration for making any oxygen corrections necessary for §115.542(a)(4) in lieu of 

using Methods 3, 3A, or 3B. 

Adopted new §115.545(10) allows additional test procedures described in 40 CFR §60.503(b) - 

(d) (effective February 14, 1989) to be used for determining compliance for bulk gasoline 

terminals. Adopted new paragraph (10) contains the same requirement in existing paragraph (5). 
41 

Adopted new §115.545(11) requires the true vapor pressure to be determined using standard 

reference texts or American Society for Testing and Materials Test Method D323-89, D2879, 

D4953, D5190, or D5191 for the measurement of Reid vapor pressure, adjusted for actual 

storage temperature in accordance with American Petroleum Institute Publication 2517, Third 

Edition, 1989. Adopted new paragraph (11) contains the same requirement in existing paragraph 

(7) with the following additions. In response to comments, the commission has also added the 

option to use standard reference texts to determine the true vapor pressure. Adopted new 

paragraph (11) also includes new language to clarify that for the purposes of temperature 

correction, the owner or operator shall use the actual storage temperature. In response to 

comments, the commission is not adopting the proposed requirement that for the purposes of 

temperature correction, the owner or operator shall use the higher of either 95 degrees Fahrenheit 

or the actual storage temperature. Adopted new paragraph (11) allows the actual storage 

temperature of an unheated tank or vessel to be determined using the maximum local monthly 

average ambient temperature as reported by the National Weather Service. Adopted new 

paragraph (11) also allows the actual storage temperature of a heated tank or vessel to be 

determined using either the measured temperature or the temperature set point of the tank or 

vessel. 

Adopted new §115.545(12) allows the test procedures in 40 CFR §63.565(c) or 40 CFR 

§61.304(f) to be used for determination of marine vessel vapor tightness. Adopted new 

paragraph (12) contains the same requirement in existing paragraph (9). 

Adopted new §115.545(13) allows LEL detectors to be used for the concentration measurement 

required by §115.542(b) and §115.544(b)(3) and (4), if the detector is calibrated and maintained 

according to manufacturer’s specifications. Adopted new paragraph (13) contains the same 

requirement in existing paragraph (11)(F) for use in the Houston-Galveston-Brazoria area and 

allows the use of LEL detectors for required concentration measurements in all areas affected by 

the rule. 

Adopted new §115.545(14) allows minor modifications to the test methods in this section to be 

used if approved by the executive director. Adopted new paragraph (14) contains the same 

requirement in existing paragraph (10). 

Adopted new §115.545(15) allows test methods other than those specified in this section to be 

used if validated by 40 CFR Part 63, Appendix A, Test Method 301 and approved by the 

executive director. Adopted new paragraph (15) establishes consistency in the rules by providing 

an affected owner or operator with the same flexibility afforded to the owner or operator of other 

units regulated in Chapter 115. 

The commission is deleting the option in existing paragraph (11)(C) to use bag samples to 

measure the VOC concentration in the Houston-Galveston-Brazoria area, if the means of 

collecting the sample and the type of bag used are appropriate and representative of the type of 

space being sampled and the analytical method used to evaluate bag contents are appropriate for 

the concentration levels and compound types. The commission is removing this option because it 

does not provide enough specificity to ensure the appropriate use of this sampling method. 
42 

The commission is deleting the option in paragraph (11)(E) to use portable hydrocarbon gas 

analyzer using an appropriate detector that is effective in the concentration range being measured 

and calibrated with compounds of interest in each case if the analyzer is calibrated and 

maintained according to the manufacturer’s specifications. The commission is removing this 

option because it does not provide enough specificity to ensure the use of appropriate 

instruments. The commission contends that the use of an instrument meeting the specifications in 

Method 21 is more appropriate for demonstrating compliance with the VOC concentration 

monitoring requirements. 

Section 115.546, Recordkeeping and Notification Requirements 

The commission is changing the title of §115.546 from Monitoring and Recordkeeping

Requirements to Recordkeeping and Notification Requirements to reflect the adopted changes to 

the content of this section to relocate the monitoring requirements to §115.544 and to require 

notification of degassing operations. 

Adopted §115.546(a) specifies the recordkeeping requirements for this division. Adopted 

subsection (a) incorporates the existing requirements in §115.546 for the owner or operator of 

any VOC storage tank, transport vessel, or marine vessel subject to the requirements in this 

division to maintain records on site for at least two years and make these records available upon 

request to authorized representatives of the executive director, the EPA, or any local air pollution 

control agency with jurisdiction. In addition, the commission is changing the record retention 

time from two years to five years for all records created on or after March 1, 2009. The 

commission is increasing the record retention time from two years to five years because the 

commission anticipates that most of the facilities subject to this division are already required to 

keep records for five years to comply with their Title V permit requirements. The new five-year 

record retention time only applies to those records generated after or during the time period two 

years before the effective date of the adopted rule. 

The commission is relettering the existing requirements in §115.546(1), (1)(A) - (C) as 

§115.546(a)(1), (a)(1)(A) - (C), respectively, with non-substantive changes necessary to comply 

with current rule formatting standards. 

Adopted §115.546(a)(1)(D) requires the affected owner or operator to keep records of the VOC 

concentration or percent LEL measurements required in §115.544(b)(3) to determine when the 

storage tank, transport vessel, or marine vessel can be vented to the atmosphere without control. 

Adopted subparagraph (D) clarifies the intent of the existing requirement in §115.546(4) to 

maintain results of any testing conducted in accordance with the provisions specified in §115.545 

includes maintaining records to demonstrate compliance with the VOC concentration limits in 

§115.542. 

Adopted §115.546(a)(1)(E) requires records of the VOC concentration or percent LEL 

measurements required in §115.544(b)(4). Adopted subparagraph (E) includes the requirements 

in existing §115.546(1)(D) for affected sources in the Houston-Galveston-Brazoria area and also 

reflects the adopted revision to include this same monitoring requirement for all affected areas 

subject to this division. 
43 

Adopted §115.546(a)(2) requires the owner or operator to maintain records of any operational 

parameter monitoring required in §115.544(b)(2) for a control device used to comply with the 

requirements in this division. 

Adopted §115.546(a)(2)(A) requires the owner or operator to maintain records of the VOC 

concentration measurements required in §115.544(b)(2)(A) for a carbon adsorption system. 

Adopted subparagraph (A) contains the existing requirements in §115.546(2)(C). 

Adopted §115.546(a)(2)(B) requires the owner or operator to maintain records of the continuous 

monitoring of the inlet and outlet gas temperature of a catalytic incinerator required in 

§115.544(b)(2)(B). Adopted subparagraph (B) contains the same requirements in existing 

§115.546(2)(B). 

Adopted §115.546(a)(2)(C) requires the owner or operator to maintain records of the continuous 

monitoring of the outlet gas temperature to ensure that the temperature is below the 

manufacturer’s recommended operating temperature for controlling the VOC vapors that are 

routed to a condensation system as required in §115.544(b)(2)(C). 

Adopted §115.546(a)(2)(D) requires the owner or operator to maintain records of the continuous 

monitoring of the exhaust gas temperature immediately downstream of a direct-flame incinerator 

as required in §115.544(b)(2)(D). Adopted subparagraph (D) contains the same requirements in 

existing §115.546(2)(A). 

Adopted §115.546(a)(2)(E) requires the owner or operator to maintain records of the continuous 

monitoring of the net heating value of the VOC vapors routed to the flare, the supplemental fuel 

added to the VOC vapors routed to the flare, or the engineering calculations required in 

§115.544(b)(2)(E). 

Adopted §115.546(a)(2)(F) requires the owner or operator to maintain records of the monitoring 

of the exhaust gas VOC concentration required in §115.544(b)(2)(F) for any control device used 

to comply with the option in §115.542(a)(4) to limit exhaust concentration. As discussed in the 

RESPONSE TO COMMENTS portion of this preamble, the commission is not adopting this 

requirement for internal combustion engines. Adopted subparagraph (F) also requires records of 

the monitoring method used to determine the VOC concentration. 

Adopted §115.546(a)(2)(G) requires the owner or operator to maintain records of the continuous 

monitoring of the combustion chamber temperature of a thermal oxidizer or vapor combustor as 

required in §115.544(b)(2)(G). Adopted subparagraph (G) also requires the owner or operator to 

maintain records of the continuous monitoring of the gas flow rate into the thermal oxidizer or 

vapor combustor to determine the residence time if necessary to demonstrate compliance with 

§115.544(c)(3). In response to comments, adopted subparagraph (G) was revised from proposal 

to apply the requirements proposed for thermal oxidizers to both thermal oxidizers and vapor 

combustors. 

Adopted §115.546(a)(2)(H) requires the owner or operator to maintain records of the continuous 

monitoring of the pressure inside the tank or vessel or the continuous monitoring of the gas flow 

rate at the inlet and outlet as required in §115.544(b)(2)(H) if a recirculation system is used to 
44 

comply with this division. Adopted subparagraph (H) also requires the owner or operator to 

maintain records of the Method 21 monitoring for VOC leaks within one hour after beginning 

any degassing operation, including the VOC measurements and the time the monitoring began. 

In response to comments, the commission is adopting §115.546(a)(2)(I) requiring the owner or 

operator to maintain records of the continuous engine exhaust gas oxygen content monitoring 

required in §115.544(b)(2)(I) if an internal combustion engine is used to comply with this 

division. 

In response to comments the commission is adopting §115.546(a)(2)(J) requiring the owner or 

operator to maintain records of the continuous operational parameter monitoring required in 

§115.544(b)(2)(J) sufficient to demonstrate proper functioning of the control device not listed in 

this paragraph. 

The commission is amending §115.546(a)(3) with non-substantive changes necessary to comply 

with current rule formatting standards. The adopted amendment to paragraph (3) also indicates 

the commission is relettering the inspection requirements in §115.544 as §115.544(a). 

The commission is amending §115.546(a)(4) with non-substantive changes necessary to comply 

with current rule formatting standards. The adopted amendment to paragraph (4) also requires 

the records to contain all applicable requirements from the commission’s Sampling Procedures

Manual, Chapter 14.0, Contents of Sampling Reports (January 2003, revision one). The 

commission adopts this recordkeeping requirement to clarify what information the commission 

expects to be included in the records of any testing conducted in accordance with the approved 

test methods in §115.545. 

 

Adopted §115.546(a)(5) requires the owner or operator to maintain records of the manufacturer’s 

instructions for installation, calibration, maintenance, and operation for any monitoring device 

used to comply with the requirements in this division. 

Adopted §115.546(b) requires that upon request by authorized representatives of the executive 

director, the owner or operator of a storage tank, transport vessel, or marine vessel in the 

Houston-Galveston-Brazoria area to notify the appropriate regional office of upcoming 

degassing operations. The adopted notification requirements facilitate the enforcement of the rule 

by allowing investigators to observe degassing operations. 

Section 115.547, Exemptions 

The commission adopts non-substantive changes to §115.547 necessary to comply with current 

rule formatting standards. 

The commission is deleting existing language in paragraph (1) to clarify the rule applicability, 

the commission adopts that this division apply to any storage tank, transport vessel, or marine 

vessel storing VOC liquids with a true vapor pressure greater than or equal to 0.5 psia under 

actual storage conditions. The commission is removing the exemption in existing paragraph (1) 

because it is no longer necessary to exempt any storage tank, transport vessel, or marine vessel 
45 

storing VOC liquids with a vapor space partial pressure less than 0.5 psia under actual storage 

conditions. 

Adopted §115.547(1) contains the portions of existing paragraph (2) that relate to storage tanks. 

Adopted paragraph (1) specifies that any storage tank with a storage capacity of less than one 

million gallons is exempt from this division. Adopted paragraph (1) also indicates that after 

January 1, 2009, in the Houston-Galveston-Brazoria area, the storage tanks listed in 

subparagraphs (A) and (B) are no longer exempt from the requirements of this division. Adopted 

subparagraph (A) clarifies that storage tanks in the Houston-Galveston-Brazoria area with a 

storage capacity greater than or equal to 250,000 gallons but less than one million gallons are no 

longer exempt from this division after January 1, 2009. Adopted subparagraph (B) clarifies that 

storage tanks in the Houston-Galveston-Brazoria area with a storage capacity greater than or 

equal to 75,000 gallons but less than 250,000 gallons storing materials with true vapor pressure 

greater than 2.6 psia are no longer exempt from this division after January 1, 2009. 

Adopted §115.547(2) exempts any transport vessel in the Beaumont-Port Arthur, Dallas-Fort 

Worth, El Paso, and Houston-Galveston-Brazoria areas with a storage capacity of less than 8,000 

gallons from the requirements in this division. 

Adopted paragraph (2) contains the portions of existing paragraph (2) that relate to transport 

vessels. 

Adopted §115.547(3) exempts any marine vessel in the Beaumont-Port Arthur and HoustonGalveston-Brazoria areas with a storage capacity of less than 420,000 gallons from the 

requirements in this division. Adopted paragraph (3) contains the portions of existing paragraph 

(2) that relate to marine vessels. The commission is deleting the reference to 10,000 barrels in the 

existing rule to be consistent with the format of the other exemptions in this section that do not 

include references to the equivalent value in barrels. 

The commission is renumbering the requirement in existing paragraph (3) as adopted 

§115.547(4) with only non-substantive changes necessary to comply with current rule formatting 

standards. 

The commission is renumbering the requirement in existing paragraph (4) as adopted 

§115.547(5) with non-substantive changes necessary to comply with current rule formatting 

standards. The commission also amends existing paragraph (4) to indicate that requirements in 

existing §115.541(b) and §115.542(b) are adopted as §115.541 and §115.542. In addition, 

adopted paragraph (5) limits this exemption to only apply for 30 calendar days after the damage 

to the cargo tank is sustained. The commission is adopting this new limit to minimize emissions 

from damaged marine vessels. 

The commission is renumbering the requirement in existing paragraph (5) as adopted 

§115.547(6) with only non-substantive changes necessary to comply with current rule formatting 

standards. 

Section 115.549, Compliance Schedules 
46 

The commission is changing the title of §115.449 from Counties and Compliance Schedules to

Compliance Schedules to establish consistency with other Chapter 115 rules. 

Adopted §115.549(a) states that affected owners or operators in Brazoria, Chambers, Fort Bend, 

Galveston, Hardin, Harris, Jefferson, Liberty, Montgomery, Orange, and Waller Counties were 

required to be in compliance with this division by November 15, 1996, and shall continue to 

comply with this division. The existing subsection (a) states that all affected persons shall 

continue to comply with this division as required by §115.930. Section 115.930 indicates that for 

all counties affected by this chapter, the final compliance dates for revisions to control 

requirements are given within the section relating to counties and compliance schedules in each 

division if the final compliance date of any provision is after the date of adoption of the current 

revision to this chapter; if the compliance dates are not specified for any provision, the 

compliance date is past and all affected persons must be and remain in compliance with the 

provision as of the original compliance date. Adopted subsection (a) establishes consistency with 

other rules in Chapter 115 and improves the readability of the rule by clearly indicting the 

compliance schedule in the same portion of Chapter 115. 

Adopted §115.549(b) indicates that all affected owners or operators in Collin, Dallas, Denton, 

and Tarrant Counties shall be in compliance with this division as soon as practicable, but no later 

than May 21, 2011. The adopted change reflects the rule compliance date for these counties that 

was recently published in the May 21, 2010, issue of the Texas Register (35 TexReg 4268) based 

on the commission’s determination that this contingency rule is necessary as a result of failure to 

attain the NAAQS for ozone by the attainment deadline. In response to comments, the 

commission is also allowing the owner or operator to delay compliance with the requirements in 

§115.544(b)(2)(E) until March 1, 2012, if compliance with this provision requires the installation 

of additional monitoring equipment. The March 1, 2012, compliance date is approximately one 

year after the effective date of this rule revision. Until the monitoring equipment necessary to 

demonstrate compliance with the requirements in §115.544(b)(2)(E) is installed, the owner or 

operator shall demonstrate compliance by using engineering calculations or other available 

monitoring or testing data. 

The commission adopts non-substantive changes to subsection (c) necessary to comply with 

current rule formatting standards. 

The commission adopts non-substantive changes to subsection (d) necessary to comply with 

current rule formatting standards. The commission also adopts amending subsection (d) to 

indicate that requirements in existing §115.542(a)(6) and (b)(5), and §115.546(1)(D) are adopted 

as §§115.542(b), 115.544(b)(4), and 115.546(a)(1)(E), respectively. The commission revised 

subsection (d) from proposal to include the accurate section references. In response to comments, 

the commission is also allowing the owner or operator to delay compliance with the requirements 

in §115.544(b)(2)(E) until March 1, 2012, if compliance with this provision requires the 

installation of additional monitoring equipment. The March 1, 2012, compliance date is 

approximately one year after the effective date of this rule revision. Until the monitoring 

equipment necessary to demonstrate compliance with the requirements in §115.544(b)(2)(E) is 

installed, the owner or operator shall demonstrate compliance by using engineering calculations 

or other available monitoring or testing data. 
47 

Appendix 2 – Excerpt from the February 11, 2011Texas Register (36 TexReg 809) 

Title 30 of the Texas Administrative Code Subchapter F (Miscellaneous Industrial Sources), 

30 TAC §§115.540 - 115.547, 115.549 

STATUTORY AUTHORITY 

The new and amended sections are adopted under Texas Water Code (TWC), §5.102, concerning 

General Powers, that provides the commission with the general powers to carry out its duties 

under the TWC; TWC, §5.103, concerning Rules, that authorizes the commission to adopt rules 

necessary to carry out its powers and duties under the TWC; TWC, §5.105, concerning General 

Policy, that authorizes the commission by rule to establish and approve all general policy of the 

commission; and under Texas Health and Safety Code (THSC), §382.017, concerning Rules, that 

authorizes the commission to adopt rules consistent with the policy and purposes of the Texas 

Clean Air Act. The new and amended sections are also adopted under THSC, §382.002, 

concerning Policy and Purpose, that establishes the commission’s purpose to safeguard the 

state’s air resources, consistent with the protection of public health, general welfare, and physical 

property; §382.011, concerning General Powers and Duties, that authorizes the commission to 

control the quality of the state’s air; and §382.012, concerning State Air Control Plan, that 

authorizes the commission to prepare and develop a general, comprehensive plan for the proper 

control of the state’s air. The new and amended sections are also adopted under THSC, 

§382.016, concerning Monitoring Requirements; Examination of Records, that authorizes the 

commission to prescribe reasonable requirements for the measuring and monitoring of air 

contaminant emissions; and THSC, §382.021, concerning Sampling Methods and Procedures, 

that authorizes the commission to prescribe the sampling methods and procedures to determine 

compliance with its rules. The new and amended sections are also adopted under Federal Clean 

Air Act (FCAA), 42 United States Code (USC), §§7401, et seq., which requires states to submit 

state implementation plan revisions that specify the manner in which the national ambient air 

quality standard will be achieved and maintained within each air quality control region of the 

state. 

The new and amended sections implement THSC, §§382.002, 382.011, 382.012, 382.016, and 

382.017, and FCAA, 42 USC, §§7401 et seq. 

§115.540. Applicability and Definitions. 

(a) Applicability. Except as specified in §115.547 of this title (relating to 

Exemptions), this division applies to degassing during, or in preparation of, cleaning any storage 

tank, transport vessel, or marine vessel containing volatile organic compounds with a true vapor 

pressure greater than or equal to 0.5 pounds per square inch absolute under actual storage 

conditions. In this division, the operator of any storage tank, transport vessel, or marine vessel 

refers to the regulated entity performing or outsourcing the degassing operation. 

(1) In the Beaumont-Port Arthur area, as defined in §115.10 of this title (relating to 

Definitions), this division applies to any storage tank, transport vessel, or marine vessel. 
48 

(2) In the Dallas-Fort Worth area, as defined in §115.10 of this title, this division 

applies to any storage tank or transport vessel in Collin, Dallas, Denton, and Tarrant Counties. 

This division does not apply to any tank or vessel in Ellis, Johnson, Kaufman, Parker, or 

Rockwall Counties. 

(3) In the El Paso area, as defined in §115.10 of this title, this division applies to any 

storage tank or transport vessel. 

(4) In the Houston-Galveston-Brazoria area, as defined in §115.10 of this title, this 

division applies to any storage tank, transport vessel, or marine vessel. 

(b) Definitions. Unless specifically defined in the Texas Clean Air Act (Texas Health 

and Safety Code, Chapter 382) or in §3.2, §101.1, or §115.10 of this title (relating to 

Definitions), the terms in this division have the meanings commonly used in the field of air 

pollution control. In addition, the following meanings apply in this division unless the context 

clearly indicates otherwise. 

(1) Cleaning--The process of washing or rinsing a storage tank, transport vessel, or 

marine vessel, or removing sludge or rinsing liquid from a storage tank, transport vessel, or 

marine vessel. 

(2) Degassing--The process of removing volatile organic compounds vapor from a 

storage tank, transport vessel, or marine vessel during, or in preparation of, cleaning. 

(3) Drain-dry floating roof tank--A floating roof tank designed to completely drain its 

entire contents to a sump in a manner that leaves no free-standing liquid in the tank or the sump. 

(4) Recirculation system--A vapor-tight system that is composed of piping, ductwork, 

connections, flow inducing devices, and a control device. The recirculation system conducts 

volatile organic compounds vapor from a storage tank, transport vessel, or marine vessel to a 

control device and conducts the exhaust from the outlet of the control device back into the same 

tank or vessel. The recirculation system does not include the storage tank, transport vessel, or 

marine vessel that is being degassed. 

(5) Storage capacity--The volume of a storage tank as determined by multiplying the 

internal cross-sectional area of the tank by the average internal height of the tank shell or the 

volume of a transport vessel or marine vessel as determined by the manufacturer’s original 

design capacity. 

(6) Storage tank--A stationary vessel, reservoir, or container used to store volatile 

organic compounds. This definition does not include: components that are not directly involved 

in the containment of liquids or vapors; subsurface caverns or porous rock reservoirs; or process 

tanks or vessels. 

(7) Vapor-tight--A condition that exists when no component of a system has a leak 

greater than 500 parts per million expressed as methane measured using Method 21 (40 Code of 

Federal Regulations Part 60, Appendix A-7). 

§115.541. Emission Specifications. 

(a) All volatile organic compounds (VOC) vapors from a storage tank, transport 

vessel, or marine vessel subject to this division must be routed to a control device in accordance 

with the requirements in §115.542 of this title (relating to Control Requirements) during 

degassing operations unless the VOC concentration, measured in accordance with the procedure 

described in §115.544(b)(3) of this title (relating to Inspection, Monitoring, and Testing 
49 

Requirements), is less than 34,000 parts per million by volume (ppmv) expressed as methane or 

50% of the lower explosive limit. 

(b) The intentional bypassing of a control device used to comply with this division is 

prohibited. Any visible VOC leak originating from the control device, or other associated 

product recovery device, must be repaired as soon as practical. 

(c) No avoidable liquid or gaseous leaks, as detected by sight or sound, may originate 

from the degassing operation. 

(d) In addition to the requirements in subsections (a) - (c) of this section, a transport 

vessel must be kept vapor-tight at all times until the VOC vapors are routed to a control device. 

(e) In addition to the requirements in subsections (a) - (c) of this section, a marine 

vessel must: 

(1) have all cargo tank closures properly secured or maintain a negative pressure 

within the vessel when a closure is opened; and 

(2) have all pressure or vacuum relief valves operating within certified limits, as 

specified by classification society or flag state, until the VOC vapors are routed to a control 

device. 

(f) In addition to the requirements in subsections (a) - (c) of this section, all VOC 

vapors from a floating roof storage tank that is not a drain-dry floating roof storage tank must be 

routed to a control device as soon as practical but no later than: 

(1) 24 hours after the tank has been emptied to the extent practical or the drain pump 

loses suction for a floating roof storage tank containing VOC liquids with a true vapor pressure 

greater than or equal to 1.5 pounds per square inch absolute (psia) under actual storage 

conditions; 

(2) 72 hours after the tank has been emptied to the extent practical or the drain pump 

loses suction for a floating roof storage tank containing VOC liquids with a true vapor pressure 

less than 1.5 psia under actual storage conditions; or 

(3) the time limit specified in a permit issued under Chapter 116 of this title (relating 

to Control of Air Pollution by Permits for New Construction or Modification) up to a maximum 

of 72 hours after the tank has been emptied to the extent practical or the drain pump loses 

suction. 

§115.542. Control Requirements. 

(a) A control device used to comply with §115.541 of this title (relating to Emission 

Specifications) must meet one of the following conditions at all times when volatile organic 

compounds (VOC) vapors are routed to the device. 

(1) The control device must maintain a control efficiency of at least 90% and must be 

operated in a manner consistent with how the device was operated during the control efficiency 

demonstration required in §115.544(c) of this title (relating to Inspection, Monitoring, and 

Testing Requirements). 

(2) The control device must be a flare that is designed and operated in accordance 

with 40 Code of Federal Regulations §60.18(b) - (f) (as amended through December 22, 2008 

(73 FR 78209)) and is lit at all times when VOC vapors are routed to the flare. 
50 

(3) The control device must be a recirculation system that does not cause the pressure 

inside the tank or vessel to increase by more than one inch water pressure above atmospheric 

pressure at any time during the degassing operation. 

(4) The VOC concentration at the outlet of the control device must be less than 500 

parts per million by volume (ppmv) at 0% oxygen, dry basis, expressed as methane. 

(b) All VOC vapors must be routed to a control device until the VOC concentration is 

less than 34,000 ppm(v) expressed as methane or less than 50% of the lower explosive limit. 

After one of the conditions has been satisfied, the tank or vessel may be vented to the atmosphere 

without control for the remainder of the degassing operation, except as specified in 

§115.544(b)(4) of this title. 

(c) Degassing equipment must be designed and operated to prevent avoidable liquid 

or gaseous VOC leaks. 

(d) When degassing is effected through the hatches or manways of a storage tank, all 

lines must be equipped with fittings that make vapor-tight connections. 

(e) When degassing is effected through the hatches of a transport vessel with a 

loading arm equipped with a vapor collection adapter, then pneumatic, hydraulic, or other 

mechanical means must be provided to force a vapor-tight seal between the adapter and the 

hatch. A means must be provided to minimize liquid drainage from the degassing equipment 

when it is removed from the hatch or to accomplish drainage before such removal. 

(f) When degassing is effected through the hatches of a marine vessel with a loading 

arm equipped with a vapor collection adapter, then pneumatic, hydraulic, or other mechanical 

means must be provided to force a vapor-tight seal between the adapter and the hatch, or a 

negative pressure inside the cargo tank must be maintained. 

A means must be provided to minimize liquid drainage from the degassing equipment when it is 

removed from the hatch or to accomplish drainage before such removal. 

§115.544. Inspection, Monitoring, and Testing Requirements. 

(a) Inspection requirements. The following inspection requirements apply during the 

degassing of any storage tank, transport vessel, or marine vessel subject to this division. 

(1) Inspection for visible liquid leaks, visible fumes, or significant odors resulting 

from volatile organic compounds (VOC) transfer operations must be conducted during each 

degassing operation. 

(2) Degassing through the affected transfer lines must be discontinued when a leak is 

observed and the leak cannot be repaired within a reasonable length of time. 

(b) Monitoring requirements. The following monitoring requirements apply during 

the degassing of any storage tank, transport vessel, or marine vessel subject to this division. 

Monitoring at least once every 15 minutes is sufficient to demonstrate compliance with the 

continuous monitoring requirements in this subsection. 

(1) Any monitoring device used to comply with this subsection must be installed, 

calibrated, maintained, and operated according to the manufacturer’s instructions. 

(2) The owner or operator shall monitor any operational parameters necessary to 

demonstrate the proper functioning of a control device used to comply with this division at all 

times when VOC vapors are routed to the device. 
51 

(A) For a carbon adsorption system, the owner or operator shall continuously monitor 

the exhaust gas VOC concentration of any carbon adsorption system that regenerates the carbon 

bed directly to determine breakthrough. Alternatively, the owner or operator shall periodically 

monitor the exhaust gas VOC determine breakthrough and switch the exhaust gas flow to fresh 

carbon for any carbon adsorption system that does not regenerate the carbon bed directly, as 

specified by 40 Code of Federal Regulations (CFR) §61.354(d) (as amended through October 17, 

2000 (65 FR 62160)), except that any monitoring must be conducted at intervals no greater than 

20% of the design carbon replacement interval. For the purpose of this division, breakthrough is 

defined as a measured VOC concentration exceeding 100 parts per million by volume (ppmv) 

above background expressed as methane. 

(B) For a catalytic incinerator, the owner or operator shall continuously monitor the 

inlet and outlet gas temperature. 

(C) For a condensation system, the owner or operator shall continuously monitor the 

outlet gas temperature to ensure the temperature is below the manufacturer’s recommended 

operating temperature for controlling the VOC vapors routed to the device. 

(D) For a direct-flame incinerator, the owner or operator shall continuously monitor 

the exhaust gas temperature immediately downstream of the device. 

(E) For a flare, the owner or operator shall use one of the following methods to 

demonstrate compliance with the requirements in 40 CFR §60.18 (as amended through 

December 22, 2008 (73 FR 78209)). 

(i) The owner or operator shall continuously monitor the net heating value of 

the gas stream routed to the flare. 

(ii) The owner or operator shall continuously monitor the total volume of 

supplemental fuel added to the gas stream routed to the flare and continuously maintain 

sufficient supplemental fuel to meet the minimum net heating value requirements in 40 CFR 

§60.18 assuming that the net heating value contribution from the degassed VOC vapor is 

equivalent to a level corresponding to 50% of the lower explosive limit (LEL). The owner or 

operator may estimate the volumetric flow rate from the tank or vessel for the purpose of this 

calculation if the flow rate of the degassed VOC vapor is not directly monitored. 

(iii) The owner or operator shall use calculations to demonstrate that for the 

material stored in the tank or vessel the net heating value of the gas stream routed to the flare 

cannot drop below the minimum net heating value requirements in 40 CFR §60.18 until the 

concentration of VOC in the vapors being routed to the flare is less than the concentration limits 

in §115.542(b) of this title (relating to Control Requirements). 

(iv) If the flare is a non-assisted flare that qualifies for the provisions in 40 

CFR §60.18(c)(3)(i), the owner or operator may elect to continuously monitor the hydrogen 

content of the gas stream routed to the flare and continuously meet the minimum 8.0% by 

volume hydrogen content requirement in lieu of the requirements in clauses (i) - (iii) of this 

subparagraph. 

(F) For any control device used to comply with the optional exhaust gas concentration 

limit in §115.542(a)(4) of this title, the owner or operator shall monitor the exhaust gas VOC 

concentration within one hour after beginning the degassing operation. The VOC concentration 

measurement must be a one-hour test run using one of the following methods: 
52 

(i) the integrated bag sampling procedure in Method 18 (40 CFR Part 60, 

Appendix A), §§8.2.1.1 - 8.2.1.4, and a total hydrocarbon analyzer that meets instrument and 

calibration specifications in Method 21; or 

(ii) Method 25A (40 CFR Part 60, Appendix A) to monitor the exhaust gas 

VOC concentration. 

(G) For a thermal oxidizer or vapor combustor, the owner or operator shall 

continuously monitor the combustion chamber temperature. If necessary to demonstrate 

compliance with subsection (c)(3) of this section, the owner or operator shall also continuously 

monitor the gas flow rate into the thermal oxidizer or vapor combustor to determine the 

combustion chamber residence time. 

(H) For a recirculation system, the owner or operator shall: 

(i) continuously monitor the pressure inside the tank or vessel or continuously 

monitor the gas flow rate at the inlet and outlet of the control device; and 

(ii) monitor all components of the recirculation system, including all valves 

and connectors, for VOC leaks using the procedure in Method 21 (40 CFR Part 60, Appendix A7) and begin this monitoring within one hour after beginning any degassing operation. A leak is 

defined as a screening concentration greater than 500 ppm(v) above background as methane for 

all components. 

(I) For an internal combustion engine, the owner or operator shall continuously 

monitor the engine exhaust gas oxygen content throughout the degassing operation. 

(J) For a control device not listed in this paragraph, the owner or operator shall 

continuously monitor one or more operational parameters sufficient to demonstrate proper 

functioning of the control device to design specifications. 

(3) The owner or operator shall monitor the VOC concentration to demonstrate 

compliance with the VOC concentration or percent LEL thresholds in §115.542(b) of this title 

and determine if the storage tank, transport vessel, or marine vessel can be vented to the 

atmosphere without control for the remainder of the degassing operation, except as specified in 

paragraph (4) of this subsection. The VOC concentration must be monitored: 

(A) once per minute for at least five minutes and all measurements must be less than 

the VOC concentration limits in §115.542(b) of this title; or 

(B) over a five-minute period using the integrated bag sampling procedure in Method 

18 (40 CFR Part 60, Appendix A) §§8.2.1.1 - 8.2.1.4 and the integrated measurement must be 

less than the VOC concentration limits in §115.542(b) of this title. 

(4) After demonstrating compliance with the applicable VOC concentration or 

percent LEL thresholds in §115.542(b) of this title in accordance with paragraph (3) of this 

subsection, the owner or operator of any storage tank, transport vessel, or marine vessel shall 

comply with one of the following conditions. 

(A) The VOC concentration inside the tank or vessel must be monitored once every 

12 hours while venting to the atmosphere without control until five consecutive measurements 

collected at 12 hour intervals are measured to be less than 34,000 ppm(v) expressed as methane 

or less than 50% of the LEL. The VOC concentration measurement required by paragraph (3) of 

this subsection may be considered the first of these five consecutive measurements. 
53 

(i)If venting to the atmosphere without control has been suspended for more than 

four hours, the VOC concentration inside the tank or vessel must be measured upon restart of the 

degassing operation. 

(ii) If any of the VOC concentration measurements equal or exceed 34,000 

ppm(v) expressed as methane or 50% of the LEL, the tank or vessel must be routed to the control 

device until the VOC concentration is below 34,000 ppm(v) expressed as methane or less than 

50% of the LEL as determined by subsection (b)(3) of this section. 

(iii) If the measured VOC concentration is less than 6,800 ppm(v) expressed as 

methane or 10% of the LEL then no further VOC concentration measurements are required. 

(B) The storage tank, transport vessel, or marine vessel can be vented to the 

atmosphere without control for the remainder of the degassing operation and no further VOC 

measurements are required if the VOC concentration inside the tank or vessel is less than 6,800 

ppm(v) expressed as methane or 10% of the LEL before the owner or operator stops routing the 

VOC vapors to a control device in accordance with §115.541 of this title (relating to Emission 

Specifications) and §115.542 of this title. 

(5) Minor modifications to the monitoring methods specified in this section may be 

approved by the executive director. Monitoring methods other than those specified in this section 

may be used if approved by the executive director and validated by 40 CFR Part 63, Appendix 

A, Method 301. 

(6) The sampling location for monitoring the VOC concentration as required by 

subsection (b)(3) of this section should be immediately before the control device or in the 

transfer line connecting from the tank or vessel to the control device. The owner or operator may 

elect to monitor the VOC concentration at a location inside the vapor space of the tank or vessel 

provided the location is representative of the VOC concentration entering the control device. 

(c) Testing requirements. The following testing requirements apply to the owner or 

operator of any storage tank, transport vessel, or marine vessel subject to the requirements in this 

division if a control device is used to comply with the emission specifications in §115.541 of this 

title. 

(1) For a control device used to comply with the requirements in §115.542(a)(1) of 

this title, an initial control efficiency demonstration must be conducted in accordance with the 

approved test methods in §115.545 of this title (relating to Approved Test Methods) and the 

device must be retested after any modification that could reasonably be expected to decrease the 

efficiency of a control device within 60 days after the modification or before being used to 

comply with the requirements in §115.542(a)(1) of this title, whichever is longer. 

(2) For a portable control device used to comply with the requirements in 

§115.542(a)(1) of this title, a periodic control efficiency demonstration must be conducted at 

least once every 60 months in accordance with the approved test methods in §115.545 of this 

title. 

(3) For a portable thermal oxidizer or vapor combustor used to comply with the 

requirements in §115.542(a)(1) of this title, the periodic control efficiency demonstration in 

paragraph (2) of this subsection will not be required if the combustion chamber temperature is at 

least 1,400 degrees Fahrenheit and the flow rate of the VOC vapors routed to the device is 
54 

limited to assure at least a 0.5 second combustion chamber residence time at all times when the 

device is in use. 

§115.545. Approved Test Methods. 

Compliance with the requirements in this division must be determined by applying one or more 

of the following test methods or procedures, as appropriate. 

(1) Methods 1 - 4 (40 Code of Federal Regulations (CFR) Part 60, Appendix A) must 

be used for determining flow rates. 

(2) Methods 3, 3A, or 3B (40 CFR Part 60, Appendix A) must be used to determine 

exhaust gas oxygen (O2) concentration for making any O2 corrections necessary for 

§115.542(a)(4) of this title (relating to Control Requirements). 

(3) Method 18 (40 CFR Part 60, Appendix A) must be used for determining gaseous 

organic compound emissions by gas chromatography. 

(A) If Method 18 is used to demonstrate compliance with the volatile organic 

compounds (VOC) concentration monitoring requirements in §115.542(b) of this title and 

§115.544(b)(4) of this title (relating to Inspection, Monitoring, and Testing Requirements), only 

one bag sample needs to be collected for each concentration measurement. 

(B) If Method 18 is used to demonstrate compliance with the VOC concentration 

monitoring requirements in §115.544(b)(2)(F) of this title for an internal combustion engine or 

any control device used to comply with the option in §115.542(a)(4) of this title to limit exhaust 

concentration, the VOC concentration must be determined by using the integrated bag sampling 

procedure in Method 18, §§8.2.1.1 - 8.2.1.4. 

(4) Method 19 (40 CFR Part 60, Appendix A) may be used for determining exhaust 

gas flow rates on combustion control devices in lieu of using Methods 1 - 4. 

(5) Method 21 (40 CFR Part 60, Appendix A-7) must be used for determining VOC 

leaks. An instrument meeting the specifications and calibration requirements in Method 21 may 

be used for demonstrating compliance with the VOC concentration monitoring requirements in 

§115.542(b) and §115.544(b)(3) and (4) of this title with the provision that the instrument 

response factor criteria in §8.1 of Method 21 may be determined using the average composition 

of the liquid in the tank rather than for each individual liquid. 

(6) Method 25 (40 CFR Part 60, Appendix A) must be used for determining total 

gaseous non-methane organic emissions as carbon. 

(7) Methods 25A or 25B (40 CFR Part 60, Appendix A) must be used for 

determining total gaseous organic concentrations using flame ionization or non-dispersive 

infrared analysis. 

(8) Method 27 (40 CFR Part 60, Appendix A) must be used for determining tanktruck leaks. 

(9) A portable O2 analyzer that is calibrated, maintained, and operated according to 

the manufacturer’s instructions may be used to determine exhaust gas O2 concentration for 

making any O2 corrections necessary for §115.542(a)(4) of this title in lieu of using Methods 3, 

3A, or 3B. 

(10) Additional test procedures described in 40 CFR §60.503(b) - (d) (effective 

February 14, 1989) must be used for determining compliance for bulk gasoline terminals. 
55 

(11) True vapor pressure must be determined using standard reference texts or 

American Society for Testing and Materials Test Method D323, D2879, D4953, D5190, or 

D5191 for the measurement of Reid vapor pressure, adjusted for actual storage temperature in 

accordance with American Petroleum Institute Publication 2517, Third Edition, 1989. For the 

purposes of temperature correction, the owner or operator shall use the actual storage 

temperature. Actual storage temperature of an unheated tank or vessel may be determined using 

the maximum local monthly average ambient temperature as reported by the National Weather 

Service. Actual storage temperature of a heated tank or vessel must be determined using either 

the measured temperature or the temperature set point of the tank or vessel. 

(12) The test procedures in 40 CFR §63.565(c) or §61.304(f) must be used for 

determination of marine vessel vapor tightness. 

(13) Lower explosive limit (LEL) detectors may be used for the percent LEL 

concentration measurement required by §115.542(b) and §115.544(b)(3) and (4) of this title, if 

the detector is calibrated and maintained according to manufacturer’s specifications. 

(14) Minor modifications to the test methods in this section may be used if approved 

by the executive director. 

(15) Test methods other than those specified in this section may be used if validated by 

40 CFR Part 63, Appendix A, Test Method 301 and approved by the executive director. 

§115.546. Recordkeeping and Notification Requirements. 

(a) Recordkeeping requirements. The owner or operator of any volatile organic compounds 

(VOC) storage tank, transport vessel, or marine vessel subject to the requirements in this division 

shall maintain the following records on site for at least two years. Any records created on or after 

March 1, 2009, must be maintained on site for at least five years. The owner or operator shall 

make these records available upon request to authorized representatives of the executive director, 

the United States Environmental Protection Agency, or any local air pollution control agency 

with jurisdiction. 

(1) For storage tank, transport vessel, or marine vessel degassing operations subject to the 

requirements in this division, the owner or operator shall maintain records of: 

(A) the type and number of storage tanks, transport vessels, and marine vessels that 

are degassed; 

(B) the chemical name and estimated liquid quantity of VOC contained in each 

storage tank, transport vessel, or marine vessel prior to degassing; 

(C) the chemical name and estimated liquid quantity of VOC removed from each 

storage tank, transport vessel, or marine vessel; 

(D) the VOC concentration or percent of lower explosive limit measurements required 

in §115.544(b)(3) of this title (relating to Inspection, Monitoring, and Testing Requirements) to 

determine when the storage tank, transport vessel, or marine vessel can be vented to the 

atmosphere without control; and 

(E) the VOC concentration or percent of lower explosive limit measurements required 

by §115.544(b)(4) of this title. 
56 

(2) For a control device used to comply with the requirements in this division, the owner 

or operator shall maintain records of any operational parameter monitoring required in 

§115.544(b)(2) of this title. These records must include, but are not limited to, the following. 

(A) For a carbon adsorption system, the owner or operator shall maintain records of 

the VOC concentration measurements required by §115.544(b)(2)(A) of this title. 

(B) For a catalytic incinerator, the owner or operator shall maintain records of the 

continuous temperature monitoring required in §115.544(b)(2)(B) of this title. 

(C) For a condensation system, the owner or operator shall maintain records of the 

continuous temperature monitoring required in §115.544(b)(2)(C) of this title. 

(D) For a direct-flame incinerator, the owner or operator shall maintain records of the 

continuous temperature monitoring required in §115.544(b)(2)(D) of this title. 

(E) For a flare, the owner or operator shall maintain records of the continuous 

monitoring or calculations required in §115.544(b)(2)(E) of this title. 

(F) For any control device used to comply with the optional exhaust concentration 

limit in §115.542(a)(4) (relating to Control Requirements) of this title, the owner or operator 

shall maintain records of the VOC concentration measurement required in §115.544(b)(2)(F) of 

this title and records of the monitoring method used. 

(G) For a thermal oxidizer or vapor combustor, the owner or operator shall maintain 

records of the continuous temperature monitoring required in §115.544(b)(2)(G) of this title. If 

necessary to demonstrate compliance with §115.544(c)(3) of this title, the owner or operator 

shall maintain records of the continuous monitoring of the gas flow rate into the thermal oxidizer 

or vapor combustor to determine the combustion chamber residence time. 

(H) For a recirculation system, the owner or operator shall maintain records of the 

continuous pressure or flow rate monitoring required in §115.544(b)(2)(H)(i) of this title and 

records of the VOC leak monitoring required in §115.544(b)(2)(H)(ii) of this title, including the 

VOC measurements and the time the monitoring began. 

(I) For an internal combustion engine, the owner or operator shall maintain records 

of the continuous engine exhaust gas oxygen content monitoring required in §115.544(b)(2)(I) of 

this title. 

(J) For a control device not listed in this paragraph, the owner or operator shall 

maintain records of the continuous operational parameter monitoring required in 

§115.544(b)(2)(J) of this title sufficient to demonstrate proper functioning of the control device 

to design specifications. 

(3) The owner or operator shall maintain records of the results of any leak inspection 

and repair conducted in accordance with the requirements in §115.544(a) of this title. 

(4) The owner or operator shall maintain records of any control efficiency 

demonstration required in §115.544(c) of this title and the results of any testing conducted in 

accordance with the provisions specified in §115.545 of this title (relating to Approved Test 

Methods). The records must contain all applicable requirements from the commission’s 

Sampling Procedures Manual, Chapter 14.0, Contents of Sampling Reports (January 2003, 

revision one). 
57 

(5) The owner or operator shall maintain records of the manufacturer’s instructions 

for installation, calibration, maintenance, and operation for any monitoring device used to 

comply with the requirements in this division. 

(b) Notification requirements. In the Houston-Galveston-Brazoria area, upon request by 

authorized representatives of the executive director, the owner or operator of any storage tank, 

transport vessel, or marine vessel subject to this division shall notify the appropriate regional 

office of upcoming degassing operations. 

§115.549. Compliance Schedules. 

(a) All affected owners or operators in Brazoria, Chambers, Fort Bend, Galveston, 

Hardin, Harris, Jefferson, Liberty, Montgomery, Orange, and Waller Counties were required to 

be in compliance with this division by November 15, 1996, and shall continue to comply with 

this division. 

(b) All affected owners or operators in Collin, Dallas, Denton, and Tarrant Counties 

shall be in compliance with this division as soon as practicable, but no later than May 21, 2011. 

If the installation of additional monitoring equipment is necessary to comply with the 

requirements in §115.544(b)(2)(E) of this title (relating to Inspection, Monitoring, and Testing 

Requirements), the owner or operator shall comply with the requirements no later than March 1, 

2012. Until the monitoring equipment necessary to demonstrate compliance with the 

requirements in §115.544(b)(2)(E) of this title is installed, the owner or operator shall 

demonstrate compliance by using engineering calculations or other available monitoring or 

testing data. 

(c) All affected owners or operators in El Paso County shall be in compliance with 

this division as soon as practicable, but no later than one year, after the commission publishes 

notification in the Texas Register of its determination that this contingency rule is necessary as a 

result of failure to attain the National Ambient Air Quality Standard for ozone by the attainment 

deadline or failure to demonstrate reasonable further progress as set forth in the 1990 

Amendments to the Federal Clean Air Act, §172(c)(9). 

(d) All affected owners or operators in Brazoria, Chambers, Fort Bend, Galveston, 

Harris, Liberty, Montgomery, and Waller Counties shall comply with the requirements in 

§§115.542(b), 115.544(b)(4), and 115.546(a)(1)(E) of this title (relating to Control 

Requirements; Inspection, Monitoring, and Testing Requirements; and Recordkeeping and 

Notification Requirements) as soon as practicable but no later January 1, 2009. If the installation 

of additional monitoring equipment is necessary to comply with the requirements in 

§115.544(b)(2)(E) of this title, the owner or operator shall comply with the requirements no later 

than March 1, 2012. Until the monitoring equipment necessary to demonstrate compliance with 

the requirements in §115.544(b)(2)(E) of this title is installed, the owner or operator shall 

demonstrate compliance by using engineering calculations or other available monitoring or 

testing data. 

This agency hereby certifies that the adoption has been reviewed by legal counsel and found to 

be a valid exercise of the agency’s legal authority. 

Filed with the Office of the Secretary of State on January 28, 2011. 

TRD-201100384 

Robert Martinez 
58 

Director, Environmental Law Division 

Texas Commission on Environmental Quality 

Effective date: February 17, 2011 

Proposal publication date: August 13, 2010 For further information, please call: (512) 239-0779 

♦ ♦ ♦ 

30 TAC §§115.541, 115.542, 115.545 

STATUTORY AUTHORITY 

The repealed sections are adopted under Texas Water Code (TWC), §5.102, concerning General 

Powers, that provides the commission with the general powers to carry out its duties under the 

TWC; TWC, §5.103, concerning Rules, that authorizes the commission to adopt rules necessary 

to carry out its powers and duties under the TWC; TWC, §5.105, concerning General Policy, that 

authorizes the commission by rule to establish and approve all general policy of the commission; 

and under Texas Health and Safety Code (THSC), §382.017, concerning Rules, that authorizes 

the commission to adopt rules consistent with the policy and purposes of the Texas Clean Air 

Act. The repeals are also adopted under THSC, §382.002, concerning Policy and Purpose, that 

establishes the commission’s purpose to safeguard the state’s air resources, consistent with the 

protection of public health, general welfare, and physical property; §382.011, concerning 

General Powers and Duties, that authorizes the commission to control the quality of the state’s 

air; and §382.012, concerning State Air Control Plan, that authorizes the commission to prepare 

and develop a general, comprehensive plan for the proper control of the state’s air. The repeals 

are also adopted under THSC, §382.016, concerning Monitoring Requirements; Examination of 

Records, that authorizes the commission to prescribe reasonable requirements for the measuring 

and monitoring of air contaminant emissions; and THSC, §382.021, concerning Sampling 

Methods and Procedures, that authorizes the commission to prescribe sampling methods. The 

repeals are also adopted under Federal Clean Air Act (FCAA), 42 United States Code (USC), 

§§7401, et seq., which requires states to submit SIP revisions that specify the manner in which 

the national ambient air quality standard will be achieved and maintained within each air quality 

control region of the state. 

The adopted repeals implement THSC, §§382.002, 382.011, 382.012, 382.016, 382.017, and 

382.021, and FCAA, 42 USC, §§7401 et seq. 

This agency hereby certifies that the adoption has been reviewed by legal counsel and found to 

be a valid exercise of the agency’s legal authority. 

Filed with the Office of the Secretary of State on January 28, 2011. 

TRD-201100385 

Robert Martinez 

Director, Environmental Law Division 

Texas Commission on Environmental Quality 

Effective date: February 17, 2011 

Proposal publication date: August 13, 2010 For further information, please call: (512) 239-0779