i.tì., r.,r:'r,

KatlrleenHartnett \Nhite,Clta innatt Larr-y R. Soivard,

Commissirtner GlennShankle,ExecutiueDireclor



## Tpxas CorørurrssroN oN

ENVIRoNMENTAL

QUALITy
?. Protecting Texasbg Reducittg and Preuenting Pollution'

Docket Nos.2006-1874-SIP, 2006-17 96-R[IL,r2006-1804-RUL r June 13,2007

RichardE-Greene,

Regional

Adnrinistrator U.S.Environmental

Protection Agency- Region 6 1445 Ross Avenue Dallas. Texas7 5202-2733 

# 3 Dear MayorGreene: f On May 23,2007, the Texas Commission on EnvironmentalQuality (Commission) adopted revisionstõne Implementation

Plan(SlP) for the Houston-Galveston-Brazoriã lHGe) eiglrt-hour ozone nonattainlnenl al'ea. Theserevisionsincludethree components- The first component is a revisionto the SIP for the HGB eight-hourozone nonattainment

a¡ea that includesadditionalVoluntary Mobile Emission Reduction Program (VMEP) commitments. In addition,

the Commission

adopted amendments

to S 114.6 and$ 114.319 in 30 Tex. Admin. Code Chapter I14, Controlof Ai¡ Pollution frorn Motor Vehicles. Theserules amend the definition of diesel fuel to include marine distillate fuels, requiring

thernto be compliantwith low emission diesel(LED) standards i¡ the HGB nonattainment area, and amend the compliance

schedule

for the infoduction of LED-compliantmarinediesel fuels into theHGB areacounties. Lurtty, rhe commission

adopred new$ 1l5.ll0 and amendmenrs ros$ 115.1l2 - ll5.l17, I l5.l19, 115.541 - 1i5.547,

andl 115.549 of 30 Tex-Admin. CodeChapter ll'5, Conh'ol of Ai¡Pollution fromVolatile OrganicCompounds.Specifically, I the new sectionandamendúrents reduce emissions of volatileorganicconipounds (VOC) û'om VOC storage anddegassing I operationsby estabiishing lrore stringent controls for fittings on floating loof storage vessels, establishingcontrol I requiretnents

or operational lirnitationsonlandingfloating roofs,establislring control requirenrents for flashelnissions fi-om I crude oil and condensate

storage tanks, andestablishing nore stringent

control requirentents

for degassing

andcleaning ofJ storage, transpoll,and marinevessels. Enclosed

are tlrese

proposed

revisions

tothe SIP,a cornplete record ofthe public hearings. the accompanying

orders, anda public lrearing certification. I lookforward toyourexpeditious approval ofthese SIPrei,isiots. o L. 

### u 6 Þ _ Ðrn rJ¡-rl 

### Þ-< -rrt EC3 v l l-t ú1 er¡ -13 6Jârë



# a'Å -jf l,¡f^,&
Kath leen Hannefi\À4lite Cha\nnan KHWtlis Enclosures ¡ cc: TheHonorable Rick Perr1,. Govenlor of Texas

Mr. Zal< CovaL- Offìce of Budget, Planning

arrd Policy,Offìceof theCovenlor Mr. Glen¡ Shankle, Executive Dù-ector. Texas Con'lllission onEnvir-onrnenta) Quaìit1, Sincerely,

P.(_).p-oi.':-3()87

6 A_ustirr. Te,.l¿rs 7åì7ìl-3û87 + 5l!,,!,?9-itl(tfl € ilrr.cr.na', ¿rcici.rr,s:: i¡'.r.r,rt.ictr¡.sLate.t:,..usTexas Commissionon EnvironmentalQuality Public Hearings January29 and 31, and February 1,6,and 8,2007 Concerning Revisions to 30 TAC Chapter 11 5 Control of Air Pollutionfrom Volatile Organic Compounds

Control of VOC Emissions from Storage 8, Degassing Operations in HGBfor the Eight-Hour Ozone Standard Rule Project No. 2006-038-1 15-ENThe Texas Commissionon EnvironmentalQuality(commission) heldpublichearingsin Houstonon January 29, 2007; Dallas on January 31, 2007; Arlington and Midlothian on February 1, 2007; Longview on February 6, 2007; and Austin on February 8, 2007, to receive testimony regarding revisionsto 30TAC Chapter 1 14,ControlofAir Pollution from Motor Vehicles; Chapter 115, Control of Air Pollution from Volatile Organic Compounds; Chapter 117, Control of Air Pollution from Nitrogen Compounds; and corresponding revisionsto the state implementationplan.

The comment period closed on February 12, 2007. All testimony and comments have been reviewed and seriously considered. This hearing record contains a complete record of the public hearings and is divided into the followirrg four sections:



### o Public Notificationand Proposal
o Written and Oral Testimony
0 Evaluation of Testimony


### o Staff Recommendations/Order

Additionalcopies ofthis hearing record are maintainedin theTCEQ centralofficeat 12100 Park 35 Circle, Austin, Texas 78753. For further information, please contact Teresa Hurley at (51 2) 239- 531

### 6.

# EVALUATION 

# OF TESTIMONY

# Texas Commission on Environmental Quality 1NTEROFFlCE MEMORANDUM

To: Commissioners Date: May 4, 2007 Thru: LaDonna Castafiuela, Chief Clerk I Glenn Shankle, Executive Director From: David C. Schanbacher, P.E.,Chief Engineer 

# b Docket No.: 2006-1804-RUL Subject: Commission Approval for Rulemaking Adoption Chapter 115, Control of Air Pollution from Volatile Organic Compounds Control of VOC Emissions from Storageand Degassing Operations in HGB for the Eight-Hour Ozone Standard Rule Project No. 2006-038-115-EN
Reasons for the rule package: The Environmental Protection Agency (EPA) designated the eightcounty Houston-GalvestonBrazoria (HGB) metropolitan area as a "moderate" ozone nonattainment area under the eight-hour ozone standard. The Federal Clean Air Act (FCAA), 42 United States Code (USC), 57410, requires states to submit to EPA by June 15, 2007, state implementation plan (SIP) revisions that contain enforceable measures to achieve the National Ambient Air Quality Standard (NAAQS). The rulemaking is part of the state's efforts to reach attainment with the eight-hour standard. The rule would require owners or operators of VOC storage tanks, transport vessels, and marine vessels located in the HGB eight-hour ozone nonattainrnent area to better control their storage and degassing operations, thereby reducing VOC emissions. The revised requirements have been developed to reduce VOC emissions that have previously been unreported or under-reported in emissionsinventories.



# . Under what authority are we adopting these changes? The rule changes are adopted under Texas Water Code (TWC), 55.102, concerning General Powers, 55.103, concerning Rules, and 55.105, concerning General Policy, that authorize the commission to adopt rules necessary to carry out its powers and duties under the TWC; and under Texas Health and Safety Code (THSC), 5382.017, concerning Rules, that authorizes the commission to adopt rules consistent with the policy and purposes of the Texas Clean Air Act. The amended rules are also adopted under THSC, 5382.002, concerning Policy and Purpose, that establishes the commission's purpose to safeguard the state air resources, consistent with the protection of public health, general welfare, and physical property; 5382.011, concerning General Powers and Duties, that authorizes the commission to control the quality of the state's air; 5382.012, concerning State Air Control Plan, that authorizes the commission to prepare and develop a general, comprehensive plan for the control of the state's air; 5382.016, concerning Monitoring Requirements; Examination of Records, that authorizes the commission to prescribe requirements for owners or operators of sources to make and maintain records of emissions measurements; and 5382.021, concerning

### Commissioners Page 2 May 4, 

### 2007 Re: Docket No. 2006-1804-RUL 

### Sampling Methods and Procedures, that authorizes the commission to prescribe the sampling methods and procedures to determine compliance with its rules.

a 

### Is this rulemaking required by federal rule or state statute? Which ones? Yes. The FCAA, 42 USC, $7410, requires states to submit SIP revisions that contain enforceable measures to achieve the NAAQS. Are there any legal deadlines by which these rules must be adopted or effective? Yes. The commission is required to submit a SIP revision by June 15, 2007. Controls must be in place by the beginning of the ozone season prior to the attainment date. For the HGB area, that is January 1, 

### 2009.

• 

### What issue(s) or problem(s) are we 

### trying to solve? The proposed rulemaking would reduce VOC emissions from storage tanks and from degassing of storage tanks, transport vessels, and marine vessels in the HGB area in order to advance the attainment of the eight-hour ozone standard. Why 

### is it important that we do 

### this rule package? The FCAA requires states to submit SIP revisions containing enforceable measures to attain the NAAQS. Additional VOC emission reductions will help the HGB area attain the eight-hour ozone NAAQS and benefit the public by improving the air quality. This rulemaking would reduce VOC emissions that have previously been unreported or under-reported in the emissions inventories. Other important background or historical information. When TCEQ and its research partners began TexAQS I1 in May 2005, one of the study's goals was to identify VOC emission sources that have been historically unreported or under-reported in the EI and could potentially be 

### contributing to the discrepancy between measured and reported emissions. TexAQS I1 remote sensing VOC project results indicate that certain types of storage tank emissions, including degassing, flash, and landing loss emissions, generally have been unreported or under-reported in the TCEQ EI. Recent data analysis, a landing loss emissions survey, and other TCEQ studies indicate that these unreported emissions could total several thousand tons per year; unreported or under-reported landing loss emissions alone in the HGB area totaled approximately 7,250 tons in 2003. The proposed rulemaking would reduce emissions from these sources as well as other sourcesofpotentially unreported tank emissions, such as slotted guidepoles and other tank fittings. Scopeof the rulemaking: The proposed rulemaking subjects owners or operators of VOC storage tanks, transport vessels, and marine vessels located in the HGB eight-hour ozone nonattainment area to revised control, monitoring, testing, recordkeeping, and reporting requirements. Compliance would be required by January 1, 2009, unless compliance would require the emptying and degassing of the storage tank. In that case, compliance would be 

### required the next time the tank is emptied and degassed but no later than January 1, 2017. (Tanks are generally taken out of service at least once every ten years.) Changesrequired by federal rule:Commissioners Page 3 May 4, 2007 Re: Docket No. 2006-1804-RUL The FCAA requires states to submit SIP revisions containing enforceable measures to attain the NAAQS. The rulemaking would help reduce VOC emissions as a part of the strategy for the area to attain the eight-hour ozone standard.



# . Changes required by state statute: None. Staff recommendations that arenot expressly required by federal rule or state statute: Require more stringent controls for tank fittings on floating roof tanks, such as slotted guidepoles and other openings in internal and external floating roofs. Limit the circumstances under which tank landings are allowed to times when the landing is necessary in order to carry out inspections or maintenance or to support a change in service to a liquid that is incompatible with the previously stored liquid. Convenience landings would not be allowed unless vapors are routed to a control device during the landing, are authorized under an emission limit or cap in a permit issued under 30 TAC Chapter 116, or fall within a 25 tpy exemption level. Require the control of 

### VOC flash emissions from crude oil and condensate storage tanks at upstream oil and gas exploration and production sites and midstream pipeline breakout stations with uncontrolled flash emissions greater than 25 tons per year. Provide options for estimating the uncontrolled flash emissions. Require the control of VOC emissions from the degassing of storage tanks with a nominal capacity of 250,000 gallons or more, or with a nominal capacity of 75,000 gallons or more storing liquids with a true vapor pressure greater than 2.6 psia. Require degassing vapors from storage vessels, transport vessels, and marine vessels in the 

### HGB area to be vented to a control device until the VOC concentration of the vapors is reduced to less than 34,000parts per million by volume as methane. Require the VOC concentration of the vapors to be monitored periodically during the degassing process using 

### an appropriatemonitoring device.



# . Require additional recordkeeping and reporting requirements to validate compliance with the proposed regulations. Impact on the regulated community:



# . Who will be affected? The adopted rule changes would affect owners and operators of storage tanks, transport vessels, and marine vessels located in the 

### HGB nonattainment area only. The proposed new storage tank requirements will affect owners or operators storing volatile organic liquids in tanks located at petroleum refineries, chemical plants, gasoline storage terminals, bulk terminals, pipeline breakout stations, and oil and natural gas production sites. The limitations on landing floating roofs would have the largest impact on for-hire bulk storage terminals. The proposed changes to the degassing rules would affect owners or operators of storage 'arks, transport vessels, and marine vessels and owners or operators of facilities that clean transport andCommissioners Page 4 May 4, 2007 Re: Docket No. 2006- 1804-RUL marine vessels. Owners and operators of tanks with capacities between 75,000 and one million gallons would be most impacted since these tanks would no longer be exempt from the degassing control requirements. Tanks with capacities between 75,000 and 250,000 gallons would only be subject to the degassing rules if the materials stored have a true vapor pressure greater than 2.6 psia. 

### Does it create a group of affected persons who were not affected previously? How? Yes. Owners or operators of tanks with capacities between 40,000 and 210,000 gallons storing crude oil and condensate at 

### oil and natural gas production sites would lose their exemption from control requirements. Tanks storing crude oil and condensate at oil and natural gas production sites and at pipeline breakout stations would also be affected by the control requirement for flash emissions. The change in criteria for determining when the tank or vessel can be vented to atmosphere would not require the use ofdegassingcontrol where it was not required previously, but would result in the control equipmentbeing used for a longer time period and thus increasing operating costs. The rule change would also add a requirement for measuring the VOC concentration of the vented gases and for keeping records of the measurements. Owners or operators of tanks with capacities of 75,000 

### - 250,000 gallons storing materials with true vaporpressure greater than 2.6 psia and tanks with capacities of 250,000 

### - 1,000,000gallons would no longer be exempt from the degassing control requirements. 

### Will there be a fiscal impact? If so, 

### estimate. Yes. Costs for controlling tank fittings are estimated at 

### $900per tank for an existing

### tank. Estimated costs for equipping slotted guidepoles with controls are $10,000per tank. Costs for limiting tank landings will depend on whether the site chooses to revise operatingpractices to limit landings, to employ add-on control devices to control emissions from tank landings, or operateunder a permitted emission limit or cap that includes landing losses. Vapor recovery equipment for flash emissions could be installed on crude oil or condensate storage tanks at a capital cost of $60,000

### - $95,000. Operating costs would be more than offset by the value of the recovered gases. Costs associated with vessel degassing vary greatly, with the maximum cost associated with large stationary storage tanks or barges estimated at $25,000per day and a minimum cost estimated at $5,000. Any costs continuing beyond 2009 would be operating, maintenance, and recordkeeping requirements. There will be no increase in fees directly resulting from this rule. 

### Impact on the public: Who will be affected? The general public in the HGB and surrounding areas would benefit from improved air quality due to lower VOC and ozone levels. 

### Does it create a group of affected persons who were not affectedpreviously? No. 

### How? Will there be a fiscal 

### impact? If so, estimate. The rules are not anticipated to have fiscal implications for the general public. 

### Impact on agency programs: There will be no new activities or responsibilities required by TCEQ as a result ofthis rulemaking. However, the increased regulation of crude oil and condensate storage at oil and gas productionCommissioners Page 5 May 4,2007 Re: Docket No. 2006-1804-RUL sites will result in additional accounts to be inspected by Field Operations Division (FOD) regional investigators to ensure compliance. Enforcement of these rules should not significantly increase the number of facilities inspected by state and local governments. The rules may increase the Office of Compliance and Enforcement's workload when inspecting affected facilities to ensure they meet the additional requirements. The rulemaking could also result in many entities recognizing the need to obtain or modify a new source review permit under Chapter 1 1 6 and a Title V operating permit under Chapter 122, thus increasing the work load for the Air Permits Division (APD). The increased number of Title V permits would also lead to an increased workload for the FOD to review compliance certifications. The rulemaking itself does not require permitting actions, but because many entities have not previously accounted for emissions addressed under this rulemaking, they may need to take some action such as obtaining additional authorization. The Industrial Emissions Assessment Section (IEAS) would review requests to use computer simulation programs to estimate flash emissions. The IEAS would already be reviewing emissions inventory submittals, which are required for sites with VOC emissions greater than 10 tons per year (tpy), and would incorporate the additional tasks into the current reviews. Stakeholder meetings: The TCEQ participated in an H-GAC stakeholder meeting 

### in March 2006 to discuss potential control strategies. The TCEQ also conducted an informational meeting October 

### 5, 2006, to present the rule concepts and answer questions. Policy issues: What policy issues are affected? Elements of the tank landing policy being developed by the APD would be incorporated in the proposed rule. Are any policies'that arenot currently based on rule being made into a rule? No. What are the consequences 

### if this rulemaking is not approved to go forward? If this rulemaking is not approved, large recently-discovered sources of VOC emissions that have not been accurately accounted for in air quality modeling would continue unabated unless sources are required to limit their emissionsby another mechanism. Are there alternatives? More stringent emission reduction requirements could be applied to NOx

, sources or other VOC sourceslocated within and surrounding the HGB nonattainrnent area. Potentially controversial matters: Legislative interest may be high as this SIP revision will coincide with the 80th Legislature. There has been ongoing legislativeinterest in the agency's efforts to address eight-hour ozone issues. Key points in adoption rulemaking schedule: Texas Register proposal publication date: December 29, 2006



# . Anticipated effective date: Juile 14, 2007

rn Six-month TexasRegister filing deadline: June 29, 2007

### Commissioners Page 6 May 4, 2007 Re: Docket No. 2006- 1804-RUL
Public comment: The commission received comments on the rule package from 13 industry representatives, three environmental groups, the EPA, Harris County Public Health and Environmental Services, and one individual. The environmental groups and the individual requested that the rules be made more stringent. EPA expressed general support for the rules and requested certain clarifications. Industry representatives requested more flexibility for controls on tank fittings and slotted guidepoles and consistency with EPA rules in 40 CFR Part 63, Subpart WW, 

### more flexibility in allowing landings of floating roofs, limitations on the applicability of flash emission controls to oil and gas exploration and production sites, a higher tank size applicability threshold for storage tank degassing requirements, and more flexibility for measuring VOC concentrationsduring degassing. No changes were made in response to requests that the rules be made more stringent, because the requests were mostly beyond the scope of the currentrulemaking. Minor clarificationswere made in response to the EPA comments. Several changes were made in response to the industry comments, as discussed below. Significantchanges 

### from proposal: In response to comments, revisions were made to $115.112(d)(2) to allow additional flexibility for slotted guidepole controls and to provide consistency with 40 CFR Part 63, SubpartWW. 

### In response to comments, revisions were made to 

### 5 115.112(d)(2)(H) to allow additional flexibility for landing floating roofs. In response to comments, requirements for control of flash emissions in $115.112(d)(4) and (5) have been limited to storage of crude oil and condensate at upstream oil and gas exploration and production sites and midstream pipeline breakout stations. Control of flash emissionsat refineries is not being pursued at this time. 

### In response to comments, the requirement to control emissions from tank degassing from tanks as small as 40,000 gallons has been changed. The degassing control requirements would apply to 

### tanks with nominal capacity of 250,000 gallons or greater and to tanks with nominal capacity of 75,000 to 250,000 gallons storing materials with true vapor pressure greater than 2.6 psia. In response to 

### comments, more options have been specified in §115.545(11) for measurement of VOC concentration. Agency contacts: 

### Teresa Hurley, P.E., Rule Project Manager, 239-5316,Air Quality Division Brad Patterson, StaffAttorney, 239-1201, Environmental Law Division Patricia Durbn, Texas Register Coordi~tor, 239-6087, General Law 

### Division Attachments
cc: 

### Chief Clerk, 5 copies Executive Director's Office Jason Skaggs Ashley K. 

### Wadick

### EVALUATION OF TESTIMONY

The Texas Commission on Environmental Quality (TCEQ or commission) adopts new 8115.110 and amendments to 8§115.112 - 115.117, 115.119, 115.541

### - 115.547, and 115.549. New 5115.1 10 and amendments to 88115.112, 115.115 

### - 115.117, 115.119, and 115.541

### - 115.547 are adopted with changes to the proposed text as published 

### in the December 29, 2006, issue of the 

### Texas Register (31TexReg 10525). Amendments to 88115.113, 115.114, and 115.549 are adopted without changes and will not be republished.

The amendments will be submittedto the United States Environmental Protection Agency (EPA)as a revision to the state implementation plan (SIP).

BACKGROUND AND SUMMARYOF THE FACTUAL BASIS FOR THE ADOPTED RULES On June 15, 2004, the 

### Houston-Galveston-Brazoria(HGB) ozone nonattainment area was classifiedas a moderate nonattainment area under the eight-hournational ambient air 

### quality standard (NAAQS) under the Federal CleanAir Act (FCAA)Amendments of 1990 (42 United States Code (USC), 887401 et seq.). For the HGB area, defined by Brazoria, Chambers, Fort Bend, Galveston, Harris, Liberty, Montgomery, and Waller Counties, the TCEQ has developed this eight-hour ozone SIP revision in accordancewith 42 USC, 87410. Hence, this rulemaking and HGB SIPrevision is part of the first step in addressing the eight-hour ozone standard for the area.

The one-hour ozone NAAQS, which preceded the eight-hour ozone standard, was revoked June 15, 2005 (69 FR 23951). However, the one-hour ozone control strategiesin the HGB area will

### remain in place. This set of strategieswill continue to reduce the amount of ozone precursors and ozone in the HGB airshed. On September6, 

### 2006 (71 

### FR 52656), EPA published approval of the HGB nonattainmentarea's one-hour ozone attainment demonstration and associated rules. The approval was published in six parts, covering the rules for the control of highlyreactive volatile organic compounds (HRVOC), the HRVOC emissioncap and trade (HECT) program, the mass emission cap and trade (MECT) program for nitrogen oxides (NOx), the one-hour ozone attainmentplan, the emissions creditbanking and trading program, and the discrete emissioncreditbanking and trading program. For a more complete background on the one-hour ozone SIP revisions please refer to Chapter 1

### of the eight-hour SIP revision that has been submitted for adoption concurrent with this rule package (Project Number 2006-027-SIPNR)

### .

The rulemaking subjects owners or operators of volatile organic compound (VOC) storage tanks, 

### transport vessels, and marine vessels located in the HGB eight-hour ozone nonattainment
area to more stringent control, monitoring, testing, recordkeeping, and reporting requirements. The revised requirements have been developed to reduce VOC emissionsthat have previously been underreported in emissions inventories (EI).

The fvst Texas Air Quality Study (TexAQS 2000) measured ambient VOC concentrationsin the Houston Ship Channel to be in greater proportions to NOx emissions than what would be expectedbased on the reported point sourceemissions inventories. Therefore, when TCEQ and its research partners began TexAQS I1 in May 2005, one of the study's primary goals was to identify VOC emission sources that have been historically unreported or underreported in the EI and could potentially be contributing to the discrepancybetween measured ambient concentrations and reported point source emissions.TexAQS 11 remote sensing VOC project results indicate that certain types of storage tank emissions, including degassing, flash, and floating roof landing loss emissions, generally have been unreported in the 

### EI. Recent data analysis, a floating roof landing loss emissions survey, and other TCEQ studies indicate that these unreported emissions could total severalthousand tons per year (tpy);unreported or underreported floating roof landing loss emissions alone in the HGB area totaled approximately 7,250tons in 2003. The rulemaking will help reduce emissions from these sources as well as other sourcesofpotentially unreported 

### tankemissions, such as slotted guidepoles and other 

### tankfittings.

SECTION BY SECTION DISCUSSION Grammatical, style, and other non-substantive corrections 

### are made throughout the rulemaking to be consistentwith 

### TexasRegister requirements, to improve readability, and to conform to the drafting standards in the 

### TexasLegislativeDrafring Manual, August 2006. Such changes include appropriateand consistentuse of acronyms, sectionreferences, and certain terminology such as "that" and "which" and "shall" and "must." These changes are not discussed further.


### Subchapter 

### B, General Volatile Organic Compound Sources Division 1,

### Storage of Volatile Organic Compounds Adopted $115.110adds ten definitions used in regulatory text. Adopted $ 115.1lO(3) defines 

### Incompatible liquid as the term is used in $115.112(d)(2)(H)(ii). The definition is intended to allow 

### tank landings when necessary for change of service to a material that would be contaminatedby the previously stored material. For example, a change in service to gasoline with a lower Reid vapor pressure (RVP) that must be performed to comply with applicable fuel requirements is considered an incompatible liquid. The definition has been revised in response to commentsto specifythat differentchemical mixtures and different gradesof liquid materialwould also be considered incompatible liquids if the liquid being introduced into the 

### tankwould be made unusable for its intended purpose due to contamination from the previously stored liquid. Adopted $115.110(10) defines 

### Tankbattery 

### as the term is used in $115.112(d)(4) and (d)(5). In response to comments, the definition has been modified to clarify that a collection of tanks at a pipeline breakout station, petroleum refinery, or petrochemical plant is not considered to be a 

### tank battery. 

### In response to comments, definitionshave been added for the terms deck cover, pole float, pole sleeve, pole wiper, slotted guidepole, internal sleeve emission control system, and flexible enclosure system. These definitionshave been added to clarify additional options for controllingemissions from slotted guidepoles that have been incorporated into $ 1 15.112(d)(2)(G).The commission has also added a definition for pipeline breakout station because the term is used in clarifying the applicability of requirements for control of flash emissions in $115.112(d)(4)and (5).
Adopted changes to $ 115.1 12amend $ 115.112(a) to specify that the existingrequirements apply to the HGB areauntil January 1, 2009. Adopted changes also add subsection (d) to specify additional requirements for storage vessels 

### in the HGB area that will take effect on January 1, 2009. In response to comment, the phrase "beginning January 1,2009," has been added to clarify when the new requirementstake effect. Adopted $115.112(d)(l) specifiesthe tank size and vapor pressure criteria that determine control requirements for 

### tanks. These are the same criteria and control requirementsthat are now effective in the HGB area. These requirements arebeing moved to subsection (d) to be at the same location as new provisions that will apply to 

### tanks in the HGB area.
Adopted $ 1 15.112(d)(2)changes the control requirements for tank fittings. 

### In response to comments, rule language has been changed to be more consistentwith language 

### in the EPAregulations in 

### 40 CFR 

### Part 63, SubpartWW, National Emission Standards for Storage Vessels 

### (Tanks)ControlLevel 2.

The proposed requirement in $115.112(d)(2)(A)that all openings in an internal or external floatingroof exceptfor automatic bleeder vents, rim space vents, and roof drains must provide
a projection below the liquid surface and be equipped with a cover, seal, or lid has been modified. The requirements for all openings except automatic bleeder vents (vacuum breaker vents) and rim space vents to provide a projectionbelow the liquid surface is separate from the requirement for all openingsexcept automatic bleeder vents (vacuumbreaker vents), rim space vents, leg sleeves, and roof drains to be equipped with a cover. The proposed wording would have incorrectly required the use of coverson fixed roof support columns. The proposed wording that the cover, seal, or lid must be equipped with a working gasket and kept in a closed position (with no visible gaps) at all times except when the opening is in actual use has been revised in response to comments to specify that required deck covers must be closed (with
no gap ofmore than 118 inch) at all time, except when they must be opened for access.
Adopted $115.112(d)(2)(B)specifies that automatic bleeder vents (also known as vacuum breaker vents) and rim space vents must be equipped with a gasketed lid, pallet, flapper, or other closure device and must be closed at all times except when required to be open to relieve
excess pressure or vacuum, in accordance with the manufacturer's design. The current rule requires only that the automatic bleeder vents and rim space vents be closed. 

### In response to comments, the language has been changed to allow use of a gasketed lid, pallet, flapper, or other closure device instead of a working gasket. Also in response to comments, language allowing automatic bleeder vents to open in accordance with the manufacturer's design has been added. For convenience, the requirementsfor automatic bleeder vents and rim space vents havebeen combined in 

### 8115.112(d)(2)(B).

Section 115.112(d)(2)(C)has been revised in response to comments to allow openings for fixed roof supportcolumns to be equipped with flexible fabric sleeve seals instead of deck covers. Adopted 

### 8115.112(d)(2)(D)requires that any roof drain that empties into the stored liquid must be equipped with a slotted membrane fabric cover or equivalent control. The current rule specifies the use of the slotted membrane fabric cover; the adopted rule allows the use of other controls. EPA regulations allow controls other 

### than slotted membrane fabric covers. Other controls can provide equivalent or superior emission reduction performance. Examples include weighted ball or ball in cage type controls. The adopted rule also specifies that the requirement does not apply to stub drains on internal floating roof 

### tanks. Stub drains are found on internal floating roof 

### tanks that have bolted decks. Their purpose is 

### to allow stored liquid @at collects on the roof to drain back into the 

### tank. Covers or other controls on these stub drains would provide minimal, if any, reduction in VOC emissions. In response to comments, the phrase "no visible gap" 

### has been changed to "no gap of more than 118inch."
Adopted 8115.1 12(d)(2)(E)states that there must be no visible holes, tears, or other openings in 

### any seal or seal fabric. Adopted $115.112(d)(2)(F)states that secondary seals on external floatingroof 

### tanks must be rim-mounted and specifies a maximum allowable area of gaps between the secondary seal and the 

### tank wall. In response to comments, the phrase 'with the exceptionof gaps that do not exceed the following specification" has been added to clarify that
a limited gap area 

### is allowed. Adopted $115.112(d)(2)(G)requires each slotted guidepole well to be controlled. The quantities of emissions reduced would depend on various factors including the 

### tank size and materid stored. As an example, a 100-footdiameter external floating roof 

### tank with 4,000,000-gallon

### capacity that stores gasoline with an RVP of 9

### pounds per square inch absolute (psia) and has 25 turnovers per year with an uncontrolled slotted guidepole would emit 11.85 tpy VOC from the guidepole alone and 14tpy total VOC fromthe tank. The same tank with a controlled slotted guidepole would have 4.5 tpy VOC fromthe guidepole alone and 6.6 tons tpy total VOC emissions. For this case, controlling the slotted guidepole would result in a 62%decrease in annual VOC emissions from the guidepole and a 53%decrease in total annual 

### tankVOC emissions. In response to comments, the wording has been changed to allow additional control options for slotted guidepoles consistent with the EPA regulations for 

### tanks in 40 CFR Part 63, Subpart

### WW, and the Storage Tank EmissionsReduction Partnership Program (STERPP). These additionalcontrolsinclude a pole wiper and a pole float, a pole wiper and a pole sleeve, an internal sleeve emission control system, retrofit to a solid guidepole system, a flexible enclosure system, and a cover over the external floating roof. Emissioncalculationsusing the EPA TANKS program indicate that emissions from a slotted guidepole in a 

### tank storing gasoline with an RVP of 10 psia couldbe reduced from 13.5 tpy down to 0.2 tpy by installing a
cover over the roof. The language in $115.112(d)(2)(G)has also been revised to qualify that the controlsfor slotted guidepoles are only required for external floating roof 

### tanks.Based on the emission calculations, emissions from slotted guidepolesin internal floating roof tanks or domed external floating roof tanks would be equivalentto emissions expected by installing slotted guidepole controls on external floating roof tanks.


### Adopted $115.112(d)(2)(H) specifies that a floating roof must be kept floating on the liquid surfaceat all times except when it must be supportedby leg supports during initial fill and other limited circumstances. Instances when the roof is supportedby its legs are referred to as "landings." Adopted $115.112(d)(2)(H)limits the circumstances under which tank landings are allowed to times when the landing is necessary either to carry out inspections or maintenance,

### or to support a change in service to a liquid that is incompatiblewith the previously stored liquid. Change in service to gasoline with a lower 

### RVP that must be 

### performed to comply with applicable fuel requirements is considered a change to a liquid that is incompatiblewith the previously stored liquid and would be allowed. Different chemical mixtures and different grades of liquid material would also be considered incompatibleliquids if the liquid being introduced into the 

### tankwould be 

### made unusable for its intended purpose due to contamination from the previously stored liquid. Tank landings for the purposes of inventory control (also known as convenience landings) would not be allowed unless vapors are routed to a control device during the time that the roof is landed, or landing emissions are within an emissions limit or cap establishedunder a 30 TAC Chapter 116permit. Convenience landingswould also be 

### allowed if sitewide landing emissions are less than 25 tpy. Emissionsfrom 

### tanklandings are higher than those that would occur while the roof is floating and have generally not been included in EI. A recent surveyby the Air Quality Division's Industrial Emissions Assessment Section indicates that an 

### additionaI 7,250 tons from 

### tank landings should have been reported in 2003. The adopted rule helps to reduce these previously unreported emissions. Storage tanks with a capacity less than 25,000 gallons and those storing material with a vapor pressure less than 1.5psia are not subject to the control requirementsbecause such tanks 

### are not required to be 

### equipped with floating roofs. As an alternativeto the adopted requirements of 

### 5 115.112(d)(2)(H)(i)- 

### (iv), 

### 5 115.112(d)(2)(H)(v)provides a compliance option where a floating roof storagetank 

### emissions limit or cap could be established inpennits issued under 30 TAC Chapter 116to control floating roof 

### tank landing emissions along with standing and working loss emissions from the 

### tank. The commission has recently established enforceable storagetank 

### emission caps with several independent, for-hirepetroleum and bulk liquid terminals in the HGB region and will allow operationunder these caps to demonstrate compliancewith the rules for reducing emissions from 

### tank landings. The emission limits or

### caps enable these terminals to reduce landing emissionsthrough a combinationof measures, including operational roof landing restrictions where feasible, lowering of leg position to minimize vapor space, restricting landed 

### tankrefill rates, degassing with controls following landings, and new and emerging control techniques. 

### In response to comments, the proposed restriction specifying the cap could not include any increasein emissionsdue to 

### tank landings that would otherwise be prohibited under 

### 6115.112(d)(2)(H)(i)- 

### (iv) has been deleted. Also in response to comments, 

### 6115.112(d)(2)(H)(vi)has been added to allow facilities with sitewide landing emissions less than 

### 25 tpy to be exempt from the restrictions on 

### tank landings. The meaning of 'initial fill" in 6115.112(d)(2)(H)has been clarified in response to comments to indicate that refilling a tank 

### that has been emptied, degassed, and cleaned according to the provisionsof Chapter 115, Subchapter 

### F, Division 3, is allowed. The word 'required" has been deleted from 6115.112(d)(2)(H)(i) in response to comments to clarify that landings are allowed for maintenance performed according to company or site maintenance plans and not just in responseto regulatory requirements. The wording in $115.112(d)(2)(H)(ii)has been revised in response to commentsto use the term 'incompatible liquid" in 6115.110. Also in response to comments, $115.112(d)(2)(H)(iv)has been changedto require control of VOC emissionsuntil the roof is within 10%by volume of being refloated, instead of until the roof is completely refloated. Commentersexpressed concern that requiring controluntil the roof was completely refloated could result in liquidsbeing drawn into the control device and causing damage.
Adopted 

### 5 115.112(d)(3)specifies that vapor recovery systemsused as a control device must maintain a minimum control efficiencyof 90%.This is the same requirement that currently applies.

### Adopted $

### 115.112(d)(4) specifiesthat flash emissions from condensate storage tanks must be controlled if condensate throughput for an individual 

### tank or the collection of 

### tanks in a tank battery prior to custody transfer is greater than 1,500barrels (63,000

### gallons)per year, unless the owner or operatordemonstrates that the emissions from the individual

### tank or the collection of 

### tanks in the 

### tankbattery are less than 25 tpy. Adopted $115.112(d)(5)specifies that flash emissions from crud oil or condensate storagetanks must be 

### controlled if uncontrolled VOC emissions from an individual 

### tank at an upstream oil or gas production site or a midstream pipeline breakout station, or collectively from a tank battery at an upstream oil or gas production site, would be greater than 25 tpy. This limit was proposed as $115.112(d)(4). The throughput limit for condensate was added 

### to the adopted rule as $115.112(d)(4)for ease of enforcement. Using default emissionfactors described later 

### in this preamble, a throughputof 1,500barrels per year of condensate would be expected to have 25 tpy of VOC emissions. If 

### an
owner or operator can demonstrate that a condensate 

### tankwith throughput greaterthan 1,500 barrels per year would have emissions less 

### than 25 

### tpy, the tank would not be 

### subjectto the flash emission controls, as allowed under the new exemption 

### in $115.117(a)(9). Crude oil and condensate typically contain dissolvedgases that flash as the pressure on the liquid is reduced. For example, flashing occurs when the liquids are routed from a separatoror other pressurized vessel to an atmospheric storagetank. The flashed gases may contain VOC 

### in additionto methane and ethane, and may 

### also entrainVOC from the stored liquid. In many cases, these gases can be 

### economicallyrouted to a vapor recovery device so that the energy content can be 

### recovered for use at the production site or the gas can be compressed and routed to the sales line. If the volume of gas is sufficient, the capital cost for these vapor recovery devices 

### can be repaid in a shorttime because of the high economic value of the recovered gas. The 25 tpy threshold for control was chosenbecause it definesthe major source level for severe nonattainment areas. The 

### HGB area was classified as severeunder the one-hour ozone standard

### before the one-hour standard was replaced with the eight-hour standard. The adopted 25 tpy threshold also represents the maximum emission rate that a site would be authorized to operate under a pennit by rule (PBR). The 25 tpy threshold applies to an individual 

### tank or to an aggregationof 

### tanks in a tank battery at an oil and gas exploration and production site. Because flashemissions could occur from any of the connected tanks, the adopted rule requires that the total emissions from all connected tanks be considered in determining whether the 25 tpy threshold is met. In response to 

### comments, the commission has specified that the requirements for controllingflash emissionsapply only to tanks and 

### tankbatteries storing crude oil and condensateprior to custody transfer at. explorationand production sites and to individual tanks at midstream pipeline breakout stations. Crude oil and condensate stored at downstream sites such as pipeline terminals, refineries, or petrochemical plants may be a source of flash emissions, but in response to comments, the commission has decided not to subject these downstream sites to the new rule at this time because the test data and test methods in support of the rule were designed to be used at oil and gasproduction sites. The commissionwill continue to evaluate the extent of flash emissionsat downstream sites and may regulate such emissions in the future. The adopted rule gives several options for estimatingthe uncontrolled flash emissions. The methods are based on estimating an emission factor in terms ofpounds of VOC emitted per barrel (lblbbl) of crude oil or condensate produced. Railroad Commission regulations in 16 TAC $3.58(b) require producers to file a monthly report of the amount of oil, casing head gas, natural gas, and condensate produced during the month. Owners or operators
can use these production records for the previous 12 months (rolling) along with the emission factor to estimate the total VOC emissions. The emission factor can be 

### determined by direct measurement of the gas over a 24-hour period. Gas volume can be 

### measured by manifolding all of the 

### tanks together and using a device such as a mass flow meter or positive displacement meter. A saniple of the gascanbe 

### analyzedusing Gas ProcessorsAssociationMethod 2286,

### Tentative Method of Extended Analysis for Natural Gas and Similar Mixtures by Temperature Programmed Gas Chromatography, or accepted EPA methods to measure the compositionof the flashed vapors. These measurements can be 

### used to calculate the pounds of VOC emitted
over the 24-hour measurement period. The pounds of VOC can then be 

### divided by the oil or condensate production 

### rate in barrels to determine the emissionrate in pounds of VOC per barrel. Instead of making direct measurements,the owner or operatorcan use default emission factors of 33.3 lblbbl of condensate or 1.6lblbbl of crude. These factors were determined in a study titled 

### VOCEmissionsfrom Oiland Condensate Storage Tanks.This study, conducted in 2006, was sponsored by the TCEQ and the Houston Advanced Research Center (HARC) and is identified as project H51C. For crude oil, owners or operatorscan use a chart found as Exhibit 2 of the EPA publication

### Lessons LeamedfromNatural Gas STAR Partners:Installing Vapor Recovery Units on Crude Oil Storage Tanks, October 2003, 

### to estimate the volume of flash gas per barrel of oil. The VOC mass emission rate can then be determinedby assuming that the hydrocarbon vapors have a molecular weight of 34 pounds per pound mole and are 48%by weight VOC. These values came from the HARC H51C study. Finally, the owner or operator
can use a computer simulationor other method approvedby the executive director to estimate flash emissions. These options are specified to minimize the burden on owners and operatorsto make direct measurements or complex calculations. If the regulated entity chooses to make directmeasurements and they yield emission rates that are higher 

### thanthose determinedby the default emission factors, EPA chart, or simulation, or if computer simulationyields results higher 

### thanthe defaultemission factors or chart, the higher rates must be used. In response to comments, rule language has been added to 

### 5 1 15.112(d)(5)to specify that the higher rates must be 

### used. The proposed rule only noted this restriction 

### in the preamble. The commission has deleted the proposed 

### 5 115.112(d)(4)(E)and combined the option to use a computer simulation with the option to use anothermethod approvedby the executive director. This language waspreviously in $115.112(d)(4)(F). The accuracy of computer simulations is entirely dependent on the accuracy of the inputs and the use of appropriate model parameters. Regulated entities will stillhave the option to use a computer simulationto estimate flash emissions, but the use must be pre-approved by the executivedirector to ensure that the results are accurate. Staff of the Industrial Emissions Assessment Section who review such calculations for EI reporting will review the simulationuse.
Nothing in the adopted rule implies authorizationof flash emissions. All emissions must be authorized according to a permit or other authorizationunder 30TAC Chapters 106or 116. The adopted rule regulates flash emissions from crude oil and condensate storage at oil or gas production sites and pipeline terminals. Flash emissionsmay also occur at storage terminals, refineries, and petrochemical plants, and crude oil and condensate are not the only sources of flash emissions. Processes in petroleum refineries and chemical plants can generate liquids containing dissolved gases that will flash when the liquid is routed from higher pressure equipmentto an atmospheric storage

### tank. Although flash emissions from these other liquids
are not regulated under the adopted rule, the commission is not implying that these emissions
are authorized. Methods specified in the EPA 

### CompilationofAir Pollutant Emission Factors (AP-42) to calculate emissions from storage tanks do not include emissions from flash. Unless these flash emissionshave been separately estimated and included in best available control technology (BACT) and health effects reviews during permitting, the emissions are not authorized even if they are not expressly prohibited by regulation in Chapter 115.
Adopted $115.115(c) specifies appropriate measuring instruments 

### and test methods for determining flash emissions if the owner or operator chooses to demonstrate compliance with the 25 tpy limit by direct measurement. The use of a mass flow meter, positive displacementmeter, or similar device must be used for determining flash gas flow rate. Conventional pitot tube or orificeplate techniques may not be appropriate for the relatively low flow rates from oil and condensate storage tanks. Flow measurements must be made over a 24-hour period representativeof normal operationto make sure that the measurements capture emissions during a typical working cycle including pumping into and out of the tanks. The language in $115.115(c)has been changed 

### to specify that at oil and gas production sites, flow measurements must be made while the producing wells are operational. The proposed rule listed this requirement, but the adopted language has been changed to clarify that it applies to measurements made at oil and gas production sites and not to measurements made at pipeline breakout stationsthat could be at some distance fromthe producing wells. Gas composition must be determined using Gas Processors Association Method 2286, TentativeMethod of Extended Analysis for Natural Gas and Similar Mixtures by Temperature Programmed Gas Chromatography, or approvedEPA test methods. The listed test methods have been changed since proposal to include standard EPA test methods for the determination of VOC composition in addition to the Gas ProcessorsAssociationMethod 2286.



### In response to comments, the term "reportable emissions" in $115.116(a) has been replaced with the term "emissions inventory reportable emissions" to avoid confusionwith the use of the term "reportable emissions" 

### as used in the general air quality rules in 30 TAC Chapter 101.
Adopted $115.116(c)(l) specifiesthat owners or operators of storage tanks that are not required to be equipped with a floating roof or vapor recovery systembecause the vapor pressure ofthe stored material is less than 1.5psia shall keep records of the material stored and the vapor pressure. These records 

### are necessary to document that material stored in fmed roof 

### tanks meets the criteria for exemption from control requirements. 

### In response to comments, thewording "length of time material is stored" has been replaced with the more precise wording "starting and ending dates when the material is stored." Commentershad expressed confusion
over the meaning of the phrase.
Adopted 

### 5115.116(c)(2) specifies that owners or operators of crude oil or condensate storage tanks with flashemissions shall keep records to verify that emissions from these tanks are below the 25 tpy criteria for exemption from control requirements. Records must be sufficient to allow investigators to determine whether flash emissions have been calculatedby an appropriate method. If a computer simulation is used, records of the input and output must be retained. In response to comments, the wording has been changed to clarify that the requirements apply only to tanks or tank batteries at explorationand production sites or to tanks atpipeline breakout stations.Also in response to comments, the requirement to project emissionsfor the next year upon request has been deleted.

The adopted amendmentto 

### 5115.117(a)(2) specifies that 

### in the HGB area, the storage of crude oil and condensate prior to custody transfer in 

### tanks with capacity less than 210,000 gallons will
no longer be exempt fromthe control requirements of Subchapter B, Division 1 after January 1, 2009. The VOC emissions from such 

### tanks at oil and gasproduction sites (especially emissions arising from flashed gases) have been found to be a significant source of VOC emissions and have previously not been reported.

A new exemption 51 15.117(a)(9)has been added to specify that if an owner or operator can demonstrate that a condensate 

### tank with throughputgreater than 1,500barrels per year would have emissions less than 25 tpy, then the 

### tank would not be subject to the flash emission controls in 

### 5115.112(d)(4).Adopted 

### 8 115.119(c) specifies that compliance with the requirements of 

### 58115.112(d), 115.1 15(c),and 115.116(c)must occur by January 1, 2009, as part of the effort to address the eight-hour ozone standard for the 

### HGB area. However, if compliancewith the new requirementswould necessitateemptying and degassing the tank, compliance would not be required until the next time the 

### tank is emptied or degassed but not later than January 1,2017. Additional emissionsthat would arise fromemptying and degassing a tank could negate the benefit of the emission controls and so would not be required solely for the purpose of installing controls. Because tanks are generally taken out of service at least once every ten years, the controls must be installed no later than ten years from the date these rules are adopted. The delay in compliance would apply only to the installationof equipment; monitoring and recordkeeping requirements must be observed beginning January 1,2009. Regulated entities that use the delay of compliance provision should be prepared tojustify why tank emptying and degassing was necessary to comply with the rules. Tanks with a nominal capacity less than 210,000 gallons (794,850 liters) storingcrude oil and condensateprior to custody transfer that
were previously exempt must comply by January 1, 2009. Since proposal, wording has been added to clarify that these 

### tanks must comply by January 1, 2009, regardless if compliance would require emptying and degassing the 

### tank.
Subchapter

### F, MiscellaneousIndustrial Sources Division 3,Degassing or Cleaning ofStationary, Marine, and Transport Vessels The adopted change to 

### 8 115.541(a)(l) specifies that after January 1, 2009, the degassing control requirements will apply to storage 

### tanks in the HGB area with a nominal capacity of 75,000 gallons or greater storing materials with a true vapor pressure greaterthan 2.6 psia or to storage 

### tanks with a nominal capacity of 250,000 gallons or more storing material with a true vapor pressure of 0.5 psia or greater. The current rule mandates degassingcontrols only to

### storage tanks with a nominal capacity of one million gallons or more. The EI 

### databasehas records of more than 950 floating roof storagetanks with capacity between 75,000 and one million gallon capacity that could be required to employ vapor recovery during tank 

### degassing under the adopted rule. There are also more than 3,000 fixed roof storage 

### tanks in this sue range, but an unknown number of these storage 

### tanks store materials with a vapor pressure less than 2.6 or 0.5 psia and will not be subject to the adopted degassing requirement. Degassing emissions from these smaller storage 

### tanks can be abated with technology similar to that used for larger 

### tanks. The sueand vapor pressure criteria for determining which storage tanks are subjectto the degassing control requirements were changed since proposal in response to comments and subsequentcost effectiveness calculationsby staff.

The adopted change to $115.542(a)(5) specifies that the current control requirements apply in the HGB area only until January 1, 2009. Adopted §115.542(a)(6) specifies new criteria for control of degassing vapors from storage

### tanks and transport vessels in the HGB area. The change requires that vaporsbe vented to a control deviceuntil the 

### VOC concentrationof the vapors is reduced to less than 34,000ppm by volume (ppmv) as methane or to less than 50%of the lower explosivelimit (LEL). The current rules specify the 34,000 ppmv concentrationas one criterion for determining when vapors can be vented to the atmosphere but also allow venting after a turnover of four vapor space volumeshas occurred. If the storage 

### tanks are drained dry and if the flow of displacement gases is measured properly, four turnovers would generally be sufficient to reduce 

### VOC concentrationsto less than 34,000ppmv. If liquid remains in the bottom of the storage tank or transport vessel, as commonly occurs due to irregularitiesin the vessel surface, the remaining liquid would continue to be a source of

### VOC emissions after the four turnover criterionhas been satisfied. The adopted rules remove the optionto vent to atmosphere after a turnover of four vapor spacevolumes has occurred.Dilution from ventilation gas used to sweep the vapor space within the vessel could also cause a reading of 34,000ppmv 

### VOC to be reached temporarily,but if liquid remains in the storage tank the concentrationcould again rise when the flow of ventilation gas ceases. The adopted revision requires continued control of the vapors until the 

### VOC concentration decreases to below 34,000 ppmv or a reading of less than 50%is obtainedon an LEL meter. The concentrationmust be rechecked periodically while the 

### tank is vented to the atmosphere to
ensure that it remainsbelow 34,000ppmv or 50%LEL. If ventilation is continuous, the concentrationmust be measured at least once every 12hours. If ventilation ceases for more than fourhours, the concentrationmust be rechecked before the tank is reopened. The 50% LEL criterion was added in response to comments. The 

### VOC concentrationequivalent to 50% LEL is less 

### than 34,000ppmv and therefore is an acceptable criterionto determinewhen degassing vapors 

### can be emitted to atmosphere. Also 

### in response to comments, lqguage

### has been added to specify that the concentration measurements are no longer required after five consecutive readings less than 34,000ppmv or less than 50%LEL have been obtained.

The adopted change to $115.542(b)(4) specifies that the stated control requirements apply in the 

### HGB area only until January 1,2009. Adopted $115.542(b)(5) specifiesnew criteria for control of degassing vapors fiom marine vessels in the 

### HGB area. The change requires vapors to be vented to a control device until the 

### VOC concentration ofthe vapors is reduced to less than 34,000ppmv as methane or 50%LEL. The current rules specify this concentrationas one criterion for determining when vapors may be vented to the atmospherebut also allow venting after a turnover of four vapor space volumes has occurred.The adopted rules remove the option to vent to atmosphere after a turnover of four vapor space volumes has occurred. This change is being adopted for degassingvapors fiom marine vessels for the same reasons discussedfor the adopted §115.542(a)(6) for storage tanks and transport vessels. The 50%LELcriterion has been added to the rule because the commission has specified that an equivalent LEL percentage can be used to determinewhen degassing need no longer be controlled for storage tanks. The current rule in $115.542(b)(4) uses 20%of the LEL as one of the criteria for when marine vessels may be vented to the atmosphere. This requirement was not changed because it applies to sources in the Beaumont-Port Arthur area as well as (until January 1, 2009) sources in the HGB area. The revised §115.542(b)(5) specifies 50%of the LEL to be consistent with the value used in $115.542(a)(6)for storage

### tanks and transport vessels. Because the LEL criterion is an optionto allow flexibility in measurement methods, using 50% instead of 20%in $1 15.142(b)(5)will not allow an increase in VOC emissionsover those allowed under $115.542(b)(4).
Adopted $115.545(11) specifiesthe methods that must be used to measure the VOC concentrationofthe storage vessels, transport vessels, or marine vessels to determine when the vapors can be vented to the atmosphere instead of to a control device. 

### In response to comments, several additional analyticalmethods have been specified to allow flexibility for the concentration measurements. However, the large potential variability in chemical composition of stored liquids necessitates carefully selecting and implementing the analytical method according to the precise chemical and physical circumstances occurring at the time of the measurement. Thus, the commission requires that sufficient records and other information be maintained to show that the alternative method used completely meet the needs of the specific instance. Examples of such records are maintenance and calibration records of all equipment, training records of equipment operators, and a written sampling plan for each instance complete with data quality objectives and QAIQC measurementparameters. The measurement should be made at the head space ofthe vessel, as close aspossible to the tank bottom 

### to ensure that theconcentrationmeasurementis representative of actual conditions, but the measurements should be made at a safe location.
Adopted $115.546(1)(D) specifies that records ofthe VOC concentration measurements required by §115.542(a)(6) and (b)(5) must be maintained. The records are necessary to documentthat degassing vapors are routed to a control device until they reach the criteria to be released to the atmosphere.

A change to $115.547(2) is adopted to state that after January 1,2009, storage tanks in the 

### HGB area with a nominal capacity of less than one million gallons but greater than or equal to 250,000 gallons or with a nominal capacity of greater than or equal to 75,000 gallons storing material with vapor pressure greater than 2.6 psia will no longer be exempt from the requirements to control degassing emissions. As discussed earlier in this preamble, degassing emissions from these smaller 

### tanks 

### can be controlled with technology similar to that used to control degassing emissions from the larger 

### tanks.The commission revised the exemption level in response to public comments.

The words "causes" and "prevents" are added to 81 15.547(4) so that the text more clearly expresses the intended meaning of the exemption.
Adopted §115.549(d) specifies that compliance with the new 

### and revised requirements must
occurby January 1, 2009, as part of the effort 

### to addressthe eight-hour ozone standard for the 

### HGB area.

### FINAL REGULATORY IMPACT ANALYSIS DETERMINATION The commissionreviewed the adopted rulemaking action in light of the regulatory analysis requirementsofTexas Government Code, 52001.0225, and determined that the rulemaking action does not meet the definition of a "major environmentalrule" as defined in that statute. A "major environmentalrule" is a rule the specific intent of which is to protect the environment or reduce risks to human health from environmental exposure and that may adversely affect in a material way the economy, productivity, competition,jobs, the environment,or the public health and safety of the state or a sector of the state. The primary purpose of this adopted rulemaking action is to require owners or operators of VOC storage 

### tanks, transportvessels, and marine vessels located in the HGB eight-hourozone nonattainmentarea to better control their storage and degassing operations, thereby reducing VOC emissions. The adopted rules assist in identifying previously unreported emissions, and reducing them appropriately. It is anticipated that this adoptedrulernaking will positively affecthuman health and the environment, and not adversely affect the economy or productivity in any material manner. Moreover, the adopted rules will improve air quality and make positive progress towards attainment of the HGB eight-hour ozone standard. Therefore, the adopted rulernaking does not constitute a major environmentalrule, and thus is not subjectto a formal regulatory analysis.

In addition, this adoptedrulemaking does not meet any of the four applicability criteriaof a "major environmental rule" as defined in the Texas Government Code. Texas Government Code, 52001.0225 applies only to a major environmental rule the result of which is to: 1) exceed a standard setby federal law, unless the rule is specifically required by state law; 2) 

### exceed an expressrequirement of state law, unless the rule is specifically required by federal law; 3) 

### exceed a requirement of a delegation agreement or contractbetween the state and an agency or representative of the federal governmentto implement a state and federal program;

### or 4) 

### adopt a rule solely under the general powers of the agency instead ofunder a specific state law.

The rulemaking action, which is designed to reduce VOC emissionsthat have previously been underreported in EI, does not exceed an expressrequirementunder federal or state law. Furthermore, there is no contractor delegation agreement that covers the topic that is the subject of this action. Finally, this rulemaking action was not developed solelyunder the general powers of the agency, but is authorized by specific sections of Texas Health and Safety Code, Chapter 382 (alsoknown as the Texas Clean Air Act), and the Texas Water Code, which
are cited in the STATUTORY AUTHORITY section of this preamble, including Texas Health and Safety Code, $

### $382.011, 382.012, and 382.017. Therefore, the adopted rulemaking does not exceed a standard set by federal law, exceed an expressrequirement of state law, exceed a requirement of a delegation agreement, nor is adopted solely under the general powers of the agency.

Based upon the foregoing, this rulemaking action is not subject to the regulatory analysis provisions of Texas Government Code, $2001.0225.

TAKINGS IMPACT ASSESSMENT Under Texas Government Code, §2007.002(5), "taking" means a governmental action that affects private real property, in whole or in part or temporarily or permanently, in a manner that requires the governmental entity to compensate the private real property owner as provided by the Fifth and Fourteenth Amendments to the United States Constitutionor $17 or $19, 

### Article I, Texas Constitution; or a governmental action that affects 

### an owner's private real property that 

### is the subject of the governmentalaction, in whole or in part or temporarily orpermanently, in a manner that restricts or limits the owner'sright to the property that would otherwise exist in the absence of the governmentalaction; and is the producing cause of a reduction of at least 25%in the market value of the affectedprivate real property, determined by comparing the market value of the property as if the governmental action is not 

### in effect and the market value of the property determined as if the governmental action is in effect.

The commission completed a takings impact assessmentfor the adopted rules. The adopted rules will not affect private real property in a manner that would require compensation to private real property owners under the United States Constitution or the Texas Constitution. The adoption also will not affect private real property in a manner that restrictsor limits an owner's right to the property that would otherwise exist in the absence of the governmental action. Therefore, the adopted rules will not cause a taking under Texas Government Code, Chapter 

### 2007.

CONSISTENCYWITH THE COASTAL MANAGEMENT PROGRAM The commission determined that this rulemaking action relates to an actionor actions subjectto the Texas Coastal Management Program (CMP) in accordance with the Coastal Coordination Act of 1991, as amended (TexasNatural Resources Code, 5533.201 et seq.), and the commission rules in 30 TAC Chapter 281, Subchapter

### B, concerning Consistency with the Texas Coastal Management Program. As required by 5281.45(a)(3) and 31 TAC $505.1l(b)(2), relating to Actions and Rules Subject to the Coastal Management Program, commission rules governing air pollutant emissions must be consistent with the applicable goals and policies of the CMP. The commissionreviewed this action for consistencywith the CMP goals and policies in accordance with the rules of the Coastal Coordination Council, and determined the action is consistentwith the applicable CMP goals and policies. The CMP goal applicable to

### this rulemaking action is the goal to protect, preserve, and enhance the diversity, quality, quantity, functions, and values ofcoastal natural resource areas (31 TAC #501.12(1)). No new
sources of air contaminants will be 

### authorized and the adopted rules will maintain at least the same level of or increase the level of emissionscontrol as the existing rules. The CMP policy applicableto this rulemaking action is the policy that commissionrules comply with federal regulations in 40 

### CFR, to protect and enhance air quality in the coastal areas (3

### 1TAC 8501.32). This rulemaking action complies with 40 CFR Part 51, Requirements for Preparation, Adoption, and Submittalof Implementation Plans. Therefore, in accordancewith 31 TAC §505.22(e), the commissionaffirmsthis rulemaking action is consistentwith CMP goals and policies.

EFFECT ON SITES SUBJECTTO THE FEDERAL OPERATING PERMITS PROGRAM The requirements of Chapter 115are applicable requirementsof 30 TAC Chapter 122. Owners
or operators of sites subjectto the Federal Operating Permit Program will be required to obtain, revise, reopen, and renew their Federal Operating Permits, as appropriate, in order to include the requirements of this adopted rulernaking.

PUBLIC COMMENT The commissionheld public hearings on thisproposal at the following times and locations: January 29, 2007, 2:00 p.m. and 6:00 p.m., Houston-GalvestonArea Council, 3555Timmons Lane, Houston; January 31, 2007, 7:00 p.m., J. ErikJonsson Central Library Auditorium, 1515Young Street, Dallas; February 1,2007,2:00 p.m., Arlington City Hall Council Chambers, 101W. Abrarns Street, Arlington; February 1, 2007, 6:00 p.m., Midlothian Conference Center, 1Community Circle, Midlothian; February 6, 2007, 2:00 p.m., Longview

### Public Library, 222 W. 

### Cotton Street, Longview; andFebruary 8, 2007, 2:00 p.m., Texas Commission on Environmental Quality, Building E, Room 201S, 12100Park 35 Circle, Austin.

The commission received comments fromBaker Botts L.L.P. on behalf of the 8-Hour Ozone SIP Coalition (EOSIPC), Associationof Electric Companies of Texas, Inc. (AECT), Celanese, Ltd., CEMA Solutions, Inc. (CEMA), Coalitionof Manufacturersfor Air Quality (COMAQ), Dow Chemical Company (Dow), Energy Business, Inc. (EBI), GEM Mobile Treatment Services, Inc. (GEM), Galveston-Houston Association for Smog Prevention (GHASP), Harris County Public Health & 

### Environmental Services (HCPHES), Houston-Sierra Club (HSC), Marathon Pipe Line (MPL), Mothers for Clean Air (MFCA), Remediation Service, Int'l (RSI), Texas Chemical Council (TCC), Texas Oil & 

### Gas Association (TxOGA), Baker Botts L.L.P.
on behalf of Texas Terminal OperatorsGroup (TTO), United StatesEnvironmental Protection Agency Region 6 

### (EPA), and one individual. State RepresentativeAM E. Hernandez of District 143, State Representative Jessica 

### Farrar of District 148,and Mayor Bill White of Houston jointly with County Judge Robert Eckels ofHarris County submitted comments on the SIP that did not have specificcomments on the proposed rules.

The comrnenters suggested modificationsto the proposed rules as stated in the RESPONSE TO COMMENTS sectionof this preamble.

RESPONSE TO COMMENTS The EPA requested that the commission provide a legend or explanation that clarifiesthe symbolsused to identify changes that will be made to the rule.

### The commissionused 

### TexasRegister format to indicatechanges to the rule. In the proposal, new rule languagewas shown in

### underline, and rule language to be deleted was in 

### brackets.

Celanese endorsed the comments provided by the TCC.



### The commission acknowledges Celanese's endorsementofthe comments provided by the TCC.

The AECT and EOSIPC expressed supportfor the process the agency has used to select the proposed control strategiesand the conclusionsreached. The EOSIPC and TxOGA also expressed support for the proposal with the technical corrections submitted by its members comments, and AECT, Dow, EOSIPC, and TCC stated that these control strategieswill result in additional progress towards attainmentof the eight-hour ozone standard in the 

### HGB area.



### The commissionappreciatesthe support.

The EPA and RSI expressed supportfor the agency's effortsto expand controls and reduce VOC emissionswithin the 

### HGB area. EBI stated that accounting for storage and transport emissions sources is "very good stewardship."



### The commissionappreciates the support.

### The EOSIPC expressed support for the commission's ongoing work to incorporate the findings of the TexAQS I1 

### field study into the developmentof new modeling episodesthat occurred in 2005 

### and 2006.



### Both the TCC and Dow support the developmentof a new modeling episode that incorporates the TexAQS 

### I1 field study results. Dow additionally suggestedthat the TCEQ should consider information resulting from industry-sponsored research projects that show point source emissions from the HGB perimeter counties have little effect on key air quality monitors in Harris County.

The commission appreciatesthe support for the technical work completed to date. The TCEQ has, and 

### will continue, to review and analyze other technical studies 

### as it moves forwardwith development of a new modeling episodeand development of appropriate control strategies for the 

### HGB area.

Both the AECT and COMAQ encouraged the agency to consider the primary reason the HGB
area cannotattainthe eight-hour ozone standard by the deadline is due to NOx and VOC emissions from on-road and off-road mobile sources, marine vessels, and other federally regulated sources. The COMAQ stated that NOx emissions from such sources are estimated to comprise about 

### 54%of the 

### 2009 NOx emissions inventory for the HGB area. The EOSIPC asserted that agency photochemicalmodeling demonstrates that on-road and non-road mobile
source emissions reductions constitute the most effective path toward the HGB area achieving attainment. The COMAQ and EOSIPC stated that significantprogress towards attainment in the HGB area cannotbe realized before substantial reductions are made 

### in mobile source emissions. COMAQ further noted the TCEQ does not have the authority to regulate emissions from

### federally regulated sources. The TCC and Dow encouraged the commission to continue promoting voluntary programs like TERP to accelerate mobile source emission reductions. AECT and COMAQ expressed support for additionallegislative funding for the TERP program. COMAQ additionally commented that the agency should emphasize that TERP has resulted in about 22 tpd 

### of NOx and VOC emissionreductions from on-road and non-road sources in the HGB area. The AECT suggested the commission continue to encouragethe EPA to take all appropriate measures to accelerate reductions of NOx and VOC emissions from onroad and non-road mobile sources, marine vessels, and other federally regulated emission sources in the HGB area. The AECT suggested the commissionencourage and support programs and initiatives that will reduce NOx and VOC emissions from on-road and non-road mobile sources in the HGB area even if the measures cannotbe used for emission reduction credits in the SIP.



### The issues brought up in these comments are beyond the scope ofthis rulemaking. The purpose of 

### this rule project is to decrease VOC 

### emissionsfrom industrial point sources that have been previously unreported or underreportedto the TCEQ 

### and to providebetter recordkeepingand reportingto formulate a more accurate inventory and enable more accuratemodelingfor future SIP 

### development.

The COMAQ encouraged the TCEQ to continue to emphasize the following facts and touse these facts in the development of the HGB eight-hour ozone SIPrules: (1) 

### emissions of NOx and VOC (including HRVOC) from industrial point sourceshave been significantly reduced since 2001; 

### and (2) TCEQ photochemicalmodeling indicates additionalNOx and VOC (including HRVOC) emissions reductions frompoint and area sources in the HGB area will not bring the 

### area into attainment with the eight-hour ozone standard. The EOSIPC stated that since2001, its member companieshave invested over two billion dollars in state-of-the-art emissions controls that have reduced ozoneprecursor emissions; the results of these investments are evident in the ambient air. Additionally, the EOSIPC asserts that independent scientific studies show that the current control strategies are reducing ozone. These decreaseshave occurred before the full implementationof the current point source NOx and HRVOC emissions control strategy that was adopted in 2004 and will be fully implemented in 2007.

The commission acknowledges the efforts that have been made by industrialpoint sources 

### in the 

### HGB area to reduce emissions. The purpose of this rule package is to reduce emissionsofVOC that have been previously unreportedor underreported in the 

### EI and thereforenot considered

### in modeling exercisesto determine the most effective control
measures to reduce ozone. Additional emission reductions from acrossthe broad spectrum of sources

### may be needed to reduce ozone levels enough to meet the eight-hour standard.

The TT0requested that the commission make changes to the proposed rule to address market realities that for-hire terminals face. HSC noted that under "Potentially Controversial Matters" in the Executive Summary for the HGB VOC rules TCEQ stated, "Representatives of terminal operatorsoppose the prohibitionof convenience tank landings." HSC expressed objection that TCEQ was allowing the regulated community to "call the shots" about rule development.

The commission has made some changes to the proposed rule as a result of the TTO comments, as discussed in the Responseto Comments sectionof this rulemaking. The referenceto the opposition of terminalowners and operators 

### to the prohibition of convenience landings 

### was intended only 

### to alertthe commissioners to communicationsthat had been received before the formalrule proposal. The prohibition 

### was included in the

### proposed rule, but after further discussion and research, 5115.112(d)(2)(H)(v)and (vi) allow for convenience landings if 

### emissions are authorized under a permit limit or emission cap in a 

### permit issued under 30TAC Chapter 116or if 

### site-wide emissionsfrom 

### tankroof landings are less 

### than 25 tpy.

Both GHASP and HSC requested that the VOC rules be 

### made more stringentbecause TCEQ has not been able to document sufficient VOC emission reductions to show attainment ofthe ozone standardby 

### 2010. Similarly,an individual commenter encouragedthe commission to place more stringentcontrols on storage tank 

### emissions.

Photochemicalmodeling has shown that VOC reductionsalone would not be 

### sufficient to allow the 

### HGB area 

### to attain the eight-hour ozone standard by 2010. The commission's responses to the commenters' specific suggestions for 

### making the VOC rulesmore stringent are detailedelsewhere in this document.

GHASP asserted that the only new control measures in the &hour ozone SIP are enhancements to on-road and non-road NOx emissions controls and encouragedthe agency to adopt additional control measures. GHASP specifically encouraged the agency to consider measures that would expand the monitoring network, track emissions events and predict future emissions event impacts, incorporate reactivitybased strategies such as trading of HRVOC and/or other VOC emissions, and control wastewater and other industrial VOC sources. GHASP stated that the HGB 

### area needs everypossible emissions reduction to achieve attainmentand generally favors industrial controls first, followed by diesel source controls.

### The commission appreciates the comment but the suggestionsare outside the scope of this rulemaking and therefore no changes were made 

### to the Chapter 

### 115 rules 

### as a result of this comment. The commission considered developing rules to require more stringent controls for wastewater facilities,but concluded that more information is needed to quantify potentially underreported emissions before effectiverules can be developed.

MFCA specifically suggested increasing VOC reductions from large industrial sources in the HGB areaby 95% or more, and both MFCA and GHASP suggested establishing controls on other VOC in addition to HRVOC in the HGB area. Additionally, GHASP encouraged the agency to consider measures that concomitantly reduce pollutants that pose additional risks, such 

### as air toxics 

### and particulates.



### The commission appreciates the comments but the suggestionsare outside the scope of this rulemaking and therefore no changes were made to the Chapter 

### 115 rules 

### as a result of these comments.
HCPHES expressed support for the amendments to Chapter 115 to reduce VOC emissions from storage 

### and degassing operations in the HGB area. The HCPHES suggested adopting and/or implementing various rules adopted by other states to reduce VOC content 

### in solvents, paints, ~d various household and cosmetic products. The HCPHES also suggested expanding the HRVOC regulationsbeyond Harris County and adding to the list of chemicals subject to the HRVOC rules.



### The commissionappreciatesthe comment in support of the Chapter 

### 115 rules and the suggestionsfor additional control measures to reduce VOC emissions. The rule sections

### associated with the HCPHES suggestions arebeyond the scope of this rulemaking and therefore no changes have been made to the rule based on the comments. Furthermore, the EPA 

### is scheduled to adopt more stringent VOC 

### content limits in paints and various household and cosmetic products

### in November 

### 2007.



### HSC commented that the rule changes for storage tanks, degassing, and flash emissions should be applied statewide.
Extending coverage of these rules to the entire state is 

### beyond the scope of 

### this rulemakiug. 

### Because the proposal only applied the rule changesto the 

### HGB 

### area, affected parties 

### in other 

### areas of the state have not received proper notice ofthe changes and would not have an opportunity to comment. Thecommission may consider extending coverage of the rule amendmentsin 

### a future rulemaking.

EBI objected to the adoption of the rule languageprior to determining the resolution of the Texas Petrochemical situation with the city of Houston. El31 

### recommended the commission expressly notify the city of Houston of the intended purpose of the regulations and suggested adding a qualifier 

### to the rule language specifying the rule does not apply to the foregoing situation.

The city of Houston 

### is aware of the proposed rule language, as evidencedby comments made by the mayor of Houston on the SIPproposal. The commissionhas made no changes to the rule 

### as a result of 

### this comment.

### HSC expressed disagreementwith the statementsin the Executive Summary for the HGB VOC rules concerningenforcement responsibilities. HSC further expressed concern that new TCEQ regulations in the past have created greatly increased workloads for investigators and requested that the commission documenthow many more investigationsand investigator hours will be required to implementthese rules. EBI expressed concerns about the commission's lack of enforcement of the regulationsthe commissionpromulgates.

The proposed increased stringency of rules for 

### tanks does not require additional inspections,just changesin compliance criteria. The changesto the degassingrules would affect additional sources, but degassing

### is done infrequently. The requirements for control of flash emissionswould impose new requirements at sites that are already subject to other commission rules for permitting and emissionsinventory reporting but may not 

### be complyingwith these requirements due tounderestimation of flash emissions. The recordkeeping requirements of the new rules could aid investigators in determining whether facilitiesare in compliancewith existiirules.



### GEM suggestedclarifying whether the term "storage vesselnused 

### in the proposed rule text refers to "storage tanks."

The term "storage vessel" 

### as used in the rule includes "storage 

### tanks." Most instances of the term "storage vessel" in the adoptedrule have been changed 

### to "storage 

### tank."

EBI suggested the Chapter 115

### rule language be revised to distinguishbetween VOC and NMVOC. EBI recommended clarifyingthat the rule applies to storage for VOC and NMVOCor limit the rule solely to crude and natural gas 

### tanks and then propose a separaterule for NMVOC.



### The defdtionof VOC 

### in 30 TAC $101.1 

### (relatingtoDefinitions) excludesmethane and other compounds determined by the EPA 

### to have a negligible contributionto tropospheric
ozone formation. Therefore, the suggested change 

### is not necessary.
COMAQ, TCC, ?TO, and Dow suggested including in $115.110 definitionsof the following terms as they are defined by the 

### EPA in 40 CFR $63.1061: pole float, pole sleeve, pole wiper, and slotted guidepole. The ?TO suggested also adding the following defmitions: deck cover, external floating roof 

### tank cover, flexible enclosure system, internal sleeve emission control system.



### The commissionhas added definitionsforthe terms deck cover, pole float, pole sleeve, pole wiper, slotted guidepole, flexible enclosure system, and internal sleeveemission control system

### as requested. 

### A definition for external floatingroof 

### tank cover 

### was not addedbecause it 

### was not necessary.

Dow suggested the TCEQ expand the definition of "incompatible liquid" in $1 15.110to include (1) liquids that have different chemical mixtures and cannot be mixed due to product quality specificationsand (2) differentgrades of liquid materials that cannot be mixed due to product quality specifications.

### In addition, Dow suggestedthat theses definition changes should be considered acceptable in $115.1 12(d)(2)(H)(ii).Dow also suggested that any liquid or fuel with a different specificationshould be considered as,anincompatibleliquid for the purposes of the rule. The ?TO suggested the rule language in $115.1lO(1) be revised to read "incompatibleliquid--a liquid that is a different chemical compound, a fuel with different regulatory specifications,or any liquid that is otherwise compatible but for commercial contractual reasons." The TCC suggested the term "incompatible" should recognize the following additional scenarios: a liquid material that would contaminate or significantly change the quality of a future stored material, any liquid or fuel with differentproduct specifications.



### The commission has revised the defmitionto include differentchemicalmixtures or different grades of liquid material that would be unusable for its intended purpose due to contamination from the previously stored liquid. Mmor differences 

### in product quality specifications or materials owned by different customers are not intendedto be covered under the definition, or the definition of incompatibleliquid would be 

### sobroad asto be practically unenforceable. The commission notes that facilities have the option to authorize landingemissionsunder a cap or emissionslimit under a Chapter 

### 116 permit or a 

### 25 tpy exemption 

### as allowed in 

### 0115.112(6)(2)(H)(v) and (mi.

The TxOGA expressed support for the definitionof "incompatibleliquid" in 

## 5115.1lO(1). The TCC agreed with the concept of allowing floating roof landings to support a change 

### in service to a liquid that is incompatible with the previously stored liquid.



### The commissionappreciates the support.

The TxOGA and TCC suggested the definitionof "tank battery" in 

### $115.1lO(2) be changed to read "Exploration and Production

### Tank Battery--A collection of equipment at an exploration and production site used to separate, treat, store, and transfer crude oil, condensate, natural gas, and produced water."

### Instead of making the change 

### as suggested, the commission is changing the 

### definition to specifythat a collection of

### tanks at a pipeline breakout station, petroleum refinery, or petrochemical plant is 

### not consideredto be a tank battery. Thecommission has also changed §115.112(d)(4) and (5) 

### to specify that control of flash emissions is required only for crude oil or condensate storage prior to custody transfer or ata pipeline breakout station. With these changes, the flash emission control requirements would apply to individual 

### tanksor the collectionof 

### tanks at anoil and gas exploration and production site and to individualtanks at a pipeline breakout station. The requirements would apply to upstream and midstream operationsbut not to downstream operations such ascrude oil and condensate storage at pipeline terminals, 

### petroleum refmeries, or petrochemical plants. The commission will 

### continueto evaluate the extent of flash emissions at the downstream operationsand may take action to regulate these sourcesata later time.



### HSC requested that the minimum control efficiency in $1

### 15.112(a)(3)and (d)(3)be 

### increased from 90%

### to 95%.

The commission made no changesto the rule 

### as a result of this comment. The focus ofthe rulemaking project

### was to effect real reductions in VOC emissions. Although the rule only requires a control efficiency of 90%, 

### many ofthe control devices 

### in use 

### in fact reduce emissions by 95% or more.



### HSC requested that the rules in 

### 51 15.112(b)and (c) for Gregg, Nueces, Victoria, Aransas, Bexar, Calhoun, Matagorda, San Patricia, 

### and Travis Countiesbe 

### changed to be 

### as stringent 

### as those for the HGB area. HSC alsorequested that all referencesin $1

### 15.112(c)(l), Table I(b), to1.5 psia be changed to 0.5 psia and that all referencesto 25,000 gallons be changed to 10,000 gallons.


### Revising the rules for the listed counties is 

### beyond the scope ofthis rulemaking. Because
no changes were proposed to thereferenced subsections, affected parties in 

### these counties have not received proper notice of the changes and would not have an opportunity to comment. The commission may consider extending coverageofthe rule amendments in 

### a future rulemaking.

HSC commented that rules 

### in $1 15.112(d) should apply statewide.


### Extending coverageto the entire state is 

### beyond the scope of this 

### rulemaking. Because the proposed rule only applied the rule changes to the HGB 

### area, affected parties 

### in other
areas ofthe statehave not received proper noticeof the changesand would not have an opportunity to comment. The commission may consider extending coverage of the rule amendmentsin 

### a futurerulemaking.

MFCA suggested requiring the installationof control measures for storage 

### tanks with VOC vapor pressure equal to or greater than 0.5 pounds per square inch absolute. GHASP commentedthat the Chapter 115 rules should be changed to reflect the best available control technology requirementsthat dictate storage 

### tanks operating with a vapor pressure greater than 0.5 psia and a capacity of more than 25,000 gallons have a floating roof or vent to control device. HSC commented that all referencesto 1.5 psia in Tables I(a) and II(a) should be changed to 0.5 psia and that all referencesto 25,000 gallons and 40,000 gallons in Tables I(a) and II(a) should be changed to 10,000 gallons.

### The commission considered lowering the vapor pressure that would trigger control requirements during the development ofthe rule proposal. After reviewing data available 

### in the 

### EI, the commission concludedthat emissions from fmed-roof 

### tanks storingmaterials with vapor pressuresbetween 

### 0.5 and 

### 1.5 psia represented a smallportion of the total VOC emissions from fmed roof 

### tanks and that requiring additionalcontrols for these 

### tanks would not provide a meaningfulreduction in VOC emissions.

Controls for smaller 

### tanks are less cost effective than controls for larger tanks. According to data 

### in the 

### EI, there are a total of 

### 3,451 fmed roof 

### tankswith a total capacity of 

### 52.8 million gallons that have capacities greater than or equalto 

### 10,000gallonsbut less than 

### 25,000 gallons in the HGB area. There are 

### 1,073 tankswith 

### total capacity of 

### 32.6 million gallonsthat have capacitiesbetween 

### 25,000 and 

### 40,000 gallons. For comparison, there are 

### 5,498 fured roof tanks with a total capacity of over 

### 14billion gallonsthat have capacities of 40,000 gallons or more. There are anadditional 

### 2,259 floating roof 

### tanks with combined capacity over 

### 24 billion gallons. The relative capacity of 

### tanks that would be affected by the requested changerepresent less than 1% 

### of the total fmed roof 

### tank capacity in the HGB and less than 

### 0.3% of the total fmed and floatingroof capacity. The commission decided not to pursue additional controls for 

### tanks that represent such a 

### small percentage of the total 

### tank capacity. Controls for these small 

### tankswould not result in meaningful emission reductions.

The EPA requested confirmation that §115.112(d) specifying additional requirements for storagevessels in the 

### HGB area will begin 

### January 1, 2009. The EPA also noted that although the preamble makes this clear, a start date of 

### January 1, 2009, 

### may need to be added to the rule.The commissionhas added the 

### start date of January 1,2009, to 5115.112(d) as suggested.

The TCC suggested incorporating the language in 40 CFR §63.1063(b)(l), (2), (3), and (5) into $1 15.112(d)(2)to addressthe operational requirements of floating roof tanks.

The commissionhas revised 5115.112(d)(2)(H) to includethe language in 40 

### CFR 563.1063(b)(l) regarding support of a floatingroof by other devices (e.g., hangers from the fixedroof). Language in 40 

### CFR 563.1063(b)(3) requiring that cavers be closed at all times except when they must be opened for access has been incorporated into 

### 9115.112(d)(2)(A). The commission declinesto add the language in 40 

### CFR §63.1063(b)(2) and 

### (5).The language in 40 

### CFR §63.1063(b)(2) would require that when the liquid depth 

### is insufficient to float the floating roof, the process of fillingto refloat the roof must be continuousand be performed as soon as practical. The restrictionson 

### tanklandings in §115.112(d)(2)0 adequately address emissions from landed floatingroofs. The requirementin 

### 40 

### CFR §63.1063(b)(5) for each unslotted guidepolecap to be closed at all times except when gauging the liquid level or taking liquid samples is addressed in §115.112(d)(2)(A).

The COMAQ and TCC suggested the rule language in $115.112(d)(2)(A)be revised to replace the phrase "no visible gapnwith the phrase "no gap of more than 118 inch." The requested change would make the TCEQ language consistent with the language in the EPA MACT standard 40 CFR §63.1063(d)(l)(v).

The commissionhas 

### made the suggested change.The TCC encouraged the agency to incorporatethe languageused in 40 CFR 

### Part 63, Subpart WW and revise 51 15.112(d)(2)(A) to allow exemption for leg sleeves from the requirement to have a cover.



### The commission has made the suggested changes.

TxOGA suggested the word "emergency" 

### be added before "roof drains" in $1 15.112(d)(2)(A) and (D).



### The commissionhas not made the suggestedchange. The wording of 6115.112(d)(2)@) specifiesthat the requirement appliestoroof drains that empty into the stored liquid. 

### A roof drain system that uses ahose or pipingto drain water from the roof to the side of the 

### tank shell does not empty into the stored liquid and so would not be subject to the control requirement.
Dow, COMAQ, and the TCC suggestedreplacing the phrase "working gasket" in $115.112(d)(2)(A)-(C)(and elsewhere 

### in the proposed document) with the phrase "gasket 

### in good operating condition" for clarity. Additionally, the TCC and COMAQ suggested revising $115.112(d)(2)(A) and (C) by changing the 

### term "rim vent" to "rim space vent."



### The commissionhas made the suggested changes.

TTO suggested the rule language in $115.112(d)(2)(A)be deleted and replaced with language from 40 CFR §63.1063(a)(2)(i) and (ii) to read "each opening except for those for automatic bleeder vents (vacuum breaker vents) and 

### rim space vents shall have its lower edge below the

### surface of the stored liquid. Each opening except for automaticbleeder vents (vacuum breaker vents), rim spacevents, leg sleeves, and deck (roof) drains shall be equipped with a deck cover. The deck cover shall be equipped with a gasket between the cover and the deck."

The commission has made the suggested changes, with slight differences in wording to correspondto the format of the existingrule 

### as well as agency guidelines, Texas Register guidelines, and Texas LegislativeDmfCingManual, August 2006.

TTO suggested the rule languagein $115.112(d)(2)(B)be deleted and replaced with language from 40 

### CFR $63.1063(b)(4)to read "each automatic bleeder vent (vacuumbreaker vent) and rim space vent shall be closed at all times, except when required to be open to relieve excess pressure or vacuv, in accordancewith the manufacturer's design." TCC suggested revising $115.112(d)(2)(B)by adding the phrase "or at the manufacturer's recommended setting" so that 

### 9115.112(d)(2)(B)will be consistentwith 41

### 15.112(d)(2)(C)and 

### with 40 CFR §63.1063(b)(4).

The commissionhas made the suggested changes.
TxOGA suggested the rule language in $115.112(d)(2)(C)be clarifiedconcerning the placement of gaskets on rim vents. TxOGA suggested that the language read "rim vent valves, if flanged, must be equipped with a working gasket and the valve be set to open only when the roof is being floated off the roof leg supports or at the manufacturer's recommended setting."

The commission

### has revised the language in 

### §115.112(d)(2) to be consistent with 

### language in 40 CFR 

### §63.1063(a)(2)(iii). The new language applicableto rim vents is in 

### §115.112(d)(2)(B). It specifes that rim space vents must be equipped with a gasketed lid,

### pallet, flapper, or other closure device instead of specifyingthat each rim vent be equipped with a gasket.



### TTOexpressed support forexempting stub drains fromthe requirements of $1

### 15.112(d)(2)(D) and agreed with the commission's assessmentthat controls on stub drains would provide minimal VOC reductions.

The commission appreciates the support.



### TxOGA suggested the rule language 

### in 

### 5 115.112(d)(2)(E)be 

### clarified to read "there must be 

### no visible holes, tears, or other openingsin 

### a primary or secondary seal or seal fabric." TxOGA expressed the opinion that the envelope on a mechanical shoe seal system is not part of the primary or secondary seal, and that the "no tear 

### or hole" requirement should not be 

### construed to apply to the envelopeon a mechanical shoe seal system.

The commissionhas not made the suggested change in the rule language because the language appliesto fabrics used to seal 

### deck 

### fittings as well asprimary and secondary 

### seals. The commission acknowledgesthat inspecting the envelope would be diff~cult in a 

### tank equipped with a secondary seal. The inspection requirements 

### in 

### 8115.114 do not require moving the secondary seal to inspect the primary seal. 

### If a hole or tear in the envelope of a mechanical shoe 

### seal

### is found, it must be repaired if it would cause an increase in VOC 

### emissions. Information available

### to commission staff indicates that the envelope is 

### part ofthe vapor barrier and thus any holes or tears found in 

### the envelope must be repaired.

### TxOGA suggested the rule language in $115.112(d)(2)(F)be clarified to read "for external floating roof storage tanks, secondary seals must be the rim-mounted type (the seal must be continuous from the floating roof to the tank 

### wall with the exception of gaps that do not exceed the following specifications). The accumulated area of gaps that exceed 118 inch (0.32 centimeters) in width between the secondary seal and the tank wall must be no greater than 

### 1.0 square inch per foot (2 1 square centimetersper meter) of tank 

### diameter."

The commission has made the requested change.


### COMAQ, Dow, MPL, and TxOGA suggested that the TCEQ allow the use of a pole sleeve option, similar to the EPA option in 40 CFR $60.1063(a)(2)(viii), to control VOC emissions from slotted guidepoles as an alternative to a gasketed float as specified in $

### 115.112(d)(2)(G). TTO suggested the rule language in $115.112(d)(2)(G)be deleted and replaced with language from both the EPA Storage Tank Emission Reduction Partnership Program (STERPP) (65 

### FR 19891,April 13, 2000) and 40 CFR §63.1063(a)(2)(viii) to read "each opening for a slotted guidepole shall be equipped with one of the following control device configurations: (i) a pole wiper and apole float. The wiper or seal of the pole float shall be at or above the height of the pole wiper, (ii) a pole wiper and a pole sleeve, (iii) an internal sleeve emission control system, (iv) a flexibleenclosure system, or (v) an external floating roof tank cover." TCC and TxOGA suggested revising $115.112(d)(2)(G)to adopt the language of 40 CFR $63.1063 as well as all other control options provided in the 

### EPA STERPP (65 

### FR 19891, April 13, 2000).

The commissionhas revised 8115.112(d)(2)(6) to include the suggested options.TTO 

### suggested the language in $115.112(d)(2)(H) be revised to read "the floating roof must be floating on the liquid surface at all times except when the floatingroof is supportedby the leg supports during the initial fill of 

### a new floating roof storage tank 

### or an existing floating roof storage 

### tank that has been degassed and/or cleaned pursuant to Subchapter

### F of this chapter, or
as allowed under the following circumstances." TTO additionally requested clarificationin preamble language concerning under which, if 

### any, circumstances uncontrolled landing emissionswould not be required to be routed to a control device in order to comply with proposed 30 

### TAC 

### 5 1

### 15.112(d)(2)(H).

The commissionhas revised the language in 0115.112(d)(2) (H)

### to allow refiof a tank that has been degassed and cleaned according to the requirements of Chapter 115, Subchapter 

### F, Division 3. 

### The commissionhas also modified preamble language to clarifythat uncoritrolled landing emissionswould be allowedunder anemissionscap as specifiedin 0115.112(d)(2)(I-l)(v) or when total landing emissionsat a site areless 

### than 25tpy as specifiedin the new 0115.112(d)(2)0(vi).

Dow suggested that $115.112(d)(2)(H)(i)be clarified sothat the phrase "when necessary for required maintenanceor inspection" includes maintenanceand inspection activities required by both environmentalregulations and by company/individual site programs. COMAQ and TCC suggested removing the term "required" from $

### 1 15.112(d)(2)(H)(i)since the term could be interpreted to mean the maintenance that is required by a particular rule.

The commission has deletedthe word "required" 

### as requested. The intent of the rule language is 

### to allow landings when needed for maintenance and inspection whether the

### activities areneeded in order to comply with environmentalregulations or to satisfy company or individual site programs.
COMAQ, TCC, and TTO suggested adding the phrase "but not limited to" after "including" in 

### 5115.112(d)(2)(H)(ii).

The commission has not made the requested change. Legally, the term "including" is understood to mean "but not limited to." The commission has changedthe wordingto use the definitionof incompatible liquid in 5115.110, 

### so the wording no longer containsthe word "including."

TTO requested that 51

### 15.112(d)(2)(H)(ii)be 

### revised to read "when necessary for supporting 

### a change in service to a liquid that is not compatible with the previously stored liquid, including but not limited to gasoline with a different RVP to comply with applicablerequirements; a termination of a contractfor the storage of a liquid; a new customer or owner of 

### a liquid coming into a storage tank; 

### or off-spec products."

The commissionhas revised the definition of "incompatible liquid" in 5115.110 and has changedthe wording of 5115.112(d)(2)(H)(iii to 

### use the definition. Landingsto replace offspec products could be allowedunder the revised definition if the product to be loaded into the 

### tankwould be contaminatedwith the previously stored off-spec product to the extent that the newly-loaded product would be 

### unusable for its intended purpose. The commission declinesto allow landingsfor commercial reasons such as 

### termination of a contract or a new customer or owner of a liquid but notes that facilities have the option to

### authorize landing emissionsunder an emission limit or cap or a 25 

### tpy exemption 

### as specifiedin 5115.112(d)(2)

### (H)(v)and (vi)

# .

HSC requested that the proposed $115.112(d)(2)(H)(iii)be revised to change the reference to 25,000 gallons to 10,000gallons and from 1.5psia to 0.5 psia.


### The purpose of the proposed $115.112(d)(2)(H)(iii) 

### was 

### to exempt floating roof 

### tanksthat store materials that could be stored in fured-roof tanks without controlsunder h115.112(d)(l) 

### from the prohibition on 

### tank landings. When a floating roof 

### is landed, the 

### tankfunctions essentially 

### as a fuedroof 

### tank, negatingthe emission reductionbenefits of the floatingroof. Because $115.112(d)(l) 

### allows materials with a vapor pressure less than 1.5 

### psia tobe stored 

### in f~ed roof 

### tanks, restrictinglandings when the materials arestored in floating roof 

### tanks would hold owners and operators who gobeyond the requirements of the rule by storing such materials 

### in floating roof 

### tanksto anunnecessarilyrestrictive standard. As discussed inresponse to other comments, the commissionhas chosen not to require materials with a vapor pressure of less than 1.5 

### psia to be 

### stored in a floatingroof 

### tank or a fmed roof 

### tank with controls.

TxOGA and TTO suggested the rule language in $115.112(d)(2)(H)(iv)be clarified to read "(H) The floating roof must be floating on the liquid surface at all times exceptwhen the floatingroof is supported by the leg supports during the initial fill or as allowed under the following circumstances: (iv) when the vapors are routed to a control device from the time the roof is landed until it is within 10%of being refloated.

### " The cornmenters expressed concern that vapor abatement equipmentmay experienceproblems if liquids are accidentally injected.

### The commission has made the requested change.

Dow expressed support for a floatingroof storage 

### tankemissions cap in $115.112(d)(2)(H)(v) and suggested that the cap does not have to be 

### sitewide in order to be 

### effective. Dow suggested
a structure similar to the TCEQ flexible air permitting program, where the regulated entity definesthe universe of the storagetanks at a given site that can be 

### included in the emissions cap. Dow also suggested allowing a single plant site to have multiple caps to address floating roof tanks in different geographical areas of the site.

The commissionhas removed the term "sitewide" from 0115.112(d)(2)(H)(v) asrequested.
COMAQ suggested clarifying $115.112(d)(2)(H)(v)to indicatethat emissions from the landing of floating roof 

### tanks can be 

### authorizedby an emission limit in a permit or permit by rule (PBR), or included in an emissions cap approved under 30TAC Chapter 116. TCC suggested removing the term "sitewide" from the preamble language and from $115.112(d)(2)(H)(v) and revising the rule language to read "tank landings that comply with established Chapter 116 emissionlimits or caps." Both Dow and TCC suggested the rule include PBR 106.263 (which
can be 

### used for 

### tank landings due to scheduled maintenance, startups, or shutdowns) as an authorization option for the landing of the floating roof tanks for a single 

### tank.

The commissionhas removed the term "sitewide" from 0115.112(d) (2)(H)(v)and added languageto clarify that landingemissionscan 

### be authorized by an emission limitor a cap under a Chapter 116permit, 

### as long as 

### the limit expressly includes landing loss emissions. The commission does not agree to allow the use of a PBR 

### to comply with 

### the provisions of #115.112(d)(2)(H). Allowing use of 

### PBR 0106.263 to authorize emissionsfrom conveniencelandings could allow a site to add up to 25tpy of VOC emissions in additionto landing loss emissions that have been authorized under an express permit 

### limit or permit cap. The provisions of §115.112(d)(2)(H) would not prevent an owner or operator from authorizing
a new 

### tank or changeof service 

### to anexisting 

### tank under an applicable PBR, but floating roof 

### tank landings from any such tanks would have to either meet the requirements of §115.112(d)(2)(H)(i) 

## - (iv) or (vi) or be incorporated into 

### an emission cap as referenced in 5115.115(d)(2)(H)(v).

TTO expressed support forthe compliance option authorizing the approval of sitewide floating roof storage tank emission caps 

### in permits issuedunder Chapter 116but objected to the language that excludes an increase 

### in caps from "otherwise prohibited roof landing emissions. TTO stated the language was vague, could 

### be read to conflictwith several existing cap agreements with the ExecutiveDirector, and the cap is more appropriately left to the commission's permitting staff. TTO suggested the language "and the cap value is not increased to account for emission from landings that would otherwise 

### be prohibited" be deleted from 

### 5115.112(d)(2)(H)(v).
The purpose ofrules 

### in Chapter 

### 115requiring emission reductions or controls from specific types of sources

### is to reduce emissions of VOC that are contributing to ozone formationin ozone nonattainment areas. Requirements in Chapter 115

### may thus be more stringent than would be required by the commission's permitting staff. The requirements for monitoringand control of HRVOC in Chapter 115, Subchapter H, are anexample. For the current rulemaking, however, the commission has deletedthe suggestedlanguage.HSC requested that $115.112(d)(2)(H)(v) be deleted. HSC objects to the use of 

### an emission cap in lieu of a prohibition on convenience landings.

For-hieterminals may have difticulty~complying with a strict prohibition on convenience landings, since the terminals do not own the liquid in the 

### tanks. Complying with individual emission limits or caps will require 

### tankowners and operators to miniielanding loss emissions while allowing them operational flexibility.

TTO suggestedadding a new $115.112(d)(2)(H)(vi)and (vii) to read "(vi) when aggregate sitewide uncontrolled VOC emissions from all floating roof 

### tank landings are less than 25 tons per year on a rolling 12-month basis using the methodologyfor landing emissions in the United StatedEnvironmental ProtectionAgency AP-42 "Compilation of Air Pollutant Emission Factors" (revised November 2006); (vii) when landing emissions are authorized under an applicable permit by rule in Chapter 106of this title."

The commission agreesthat anexemption from the prohibition on roof landings

### is appropriate for facilitieswith low landing loss emissions and has therefore added 

### 5115.112(d)(2)

### (H)(vi) to provide an exemptionfor facilities with sitewideemissions less than 

### 25 tpy. As noted in responseto a previous comment, the commission does not 

### agree to allow the use of a 

### PBRto comply 

### with the provisions of $115.112(d)(2)(H).

GHASP suggestedthat the vapor recovery system control efficiency requirements in $ 115.112(d)(3) be changed from 90%to 95% citing that the New Source Performance Standards specify a minimum control efficiency of 95%.

### The commission made no changes to the rule in 

### response to 

### this comment. The focus of the rulemaking project 

### was to effect real reductions

### in VOC emissions. Although the rule only requires a control efficiency of 90%,

### many of the control devices

### in use in 

### fact reduce emissions by 95% 

### or more.

HSC requested that $115.112(d)(4)be 

### made more stringent by requiring control of flash emissions for tanks 

### with emissions of greater 

### than or equal 

### to 10tpy instead of the proposed level of 25 tpy

### .

The cost effectiveness of controls decreases proportionally to a source's emissionsrate. If
no pipeline 

### is available

### to transport recoveredvapors, emissions and energy use from tanker trucks would counter some of the benefits from vapor recovery. Other statesthat explicitly require control of flash emissions includeWyoming and Colorado. Wyoming requires control if uncontrolledemissions are greater than or equal to 

### 40 tpy. The statewide Colorado rule requires control if 

### uncontrolled emissions aregreater than or equalto 20

### tpy. The commenter gave no specific justification for the proposed level of 10tpy. Furthermore, the 

### EPA expressed support for the 25 

### tpy threshold.

EPA 

### endorsed the 25 tpy threshold for control because it 

### defines the major source level for
severe ozone nonattainment areas.

The commission appreciates the support.

The TCC commented that the vapor pressure of certain liquid streams at oil and gas exploration and production sitesmay be 

### greater than 

### 11psia because of the presence of entrained gas. TCC

### further requested the commission clarify that tanks 

### containing crude oil and condensate streams that have a true vapor pressure less than 11 psia and meet the control requirements of §115.112 Table l(a), including storage in an external floating roof with a primary and secondary seal, are adequately controlled for the purposes of this rule.

The commission does not agree 

### that crudeoil and condensate streamswith a reported true vapor pressure less than 11psia do not have flash emissions nor that storage in an external floatingroof 

### tank with primary and secondary seals provides adequate control if flash emissionsare occurring. The commission acknowledges that the highest flash emissions would be expectedto occur at upstream oil and gas exploration and production siteswhen the 

### stream is fust exposed to atmospheric pressure. 

### Tanks at

### midstreampipeline breakout stationswould alsobe expectedto have higher potential for flash emissions than 

### tanks at downstreampetroleum refineries or petrochemical plants. For these reasons, the commission has revised the rule to require control of flash emissions only atthe upstream oil and gas exploration and production sites and at

### midstreampipeline breakout stations.

The TCC suggestedthe preamble (specificallypages 17 and 18)be revised to remove references to crude oil and condensate storage at all locations other than explorationand production facilities.Additionally, the TCC requested the commissionclarify that the term 

### "condensatenapplies to the liquids produced from natural gas rather than 

### those 

### tanks at a petroleumplant that may receive condensate from a natural gas production site. TxOGA requested that the term "tanksnin $115.112(d)(4) be revised to the phrase "explorationand production 

### tanks."

### The commissionhas changed 5115.112(d)(4) and (5) 

### to specify that control of flash emissionsis required only for crudeoil or condensatestorageatupstream oil and gas exploration and production sites prior to custody transfer or at pipeline breakout stations. The requirements would not apply to downstreamoperationssuch 

### as crude oil and condensate storage atpetroleumrefineriesor petrochemical plants. Remote sensing projectscarried out under TexAQS 

### II foundplumes from crude oil storage

### tanks 

### at refineries. Crude oil and condensatetransferred downstream may stiU contain dissolved gases; thus, flash emissions could stillbe occurringatthese downstreamlocations. However, the H51C study that was used to determine default emission factors for crude oil and condensate storagetested 

### tanks at upstream sites only, and the test methodsthat were used to

### measure the emissionswould not be applicableto large external floatingroof storage

### tanks such asthose typically used atrefineries. Tanks 

### atmidstream pipeline breakout stations arealso regulated under the rule 

### as adopted. Crude oil and condensate that have been transferred through pressurized pipelines arelikely to flash when transferred to atmospheric storage

### tanks. The commission will continueto evaluate the extent of flash emissionsatthe downstreamoperationsand may 

### take actionto regulate these sourcesata later time.

The 

### TCC suggested consistencybetween the actual rule language 

### in $115.112(d)(4) and the preamble for the rule with regards to estimating flash emissions using the method that yields the higher emission rate.



### The commission has moved the requirementsthat were proposed as §115.112(d)(4) to 5115.112(d)(5) and has 

### revised the languageto statethat if emissions determinedusing direct measurements or other metbods approvedby the executive director under

### §115.112(d)(5)(A) or (D) 

### arehigher than emissions estimated using the default factors or charts in §115.112(d)(5)(B) or 

### (C), the higher values must be used. The intent of allowing the use of default emission factorsis 

### to enable regulated entities to avoid the cost of performingmeasurements or complex computer simulations. However, if 

### the regulated entity choosesto use one of the more accurate, site-specificemission determination methods, this informationshould be used in determining whether emissionsexceedthe 25 tpy threshold.

The TCC requested clarificationthat simulationmethods acceptablefor use to estimate flash emissions include API E&P 

### Tank Model and any other model as listed in the TCEQ EI guidance document (Technical Supplement 6, 

### January, 2007).



### The 

### EI guidance document lists 

### a number of methods for estimatingflash 

### emissionsand ranks them accordingto expected accuracy. These methods areused state-wide. Flash emissions have traditionallybeen under reported, and one goal of the current rulemaking is to obtain a better accountingof these emissions in the HGB area. Thus, some of the methods that 

### may be acceptablefor estimating flash emissionsin ozone attainment areas in West Texasmay not be accurate for sources in the HGB area. The use of any simulationmethod is 

### problematic, because the model must be 

### run correctlyusing proper input datain order to get accurate results. Because of these problems, the commission has revised $115.112(d)(5) to delete the proposed §115.112(d)(4)(D) 

### that would have allowed the use of computer simulations. The new §115.112(d)(5)@) allowsthe use of other test methods or computer simulations pre-approved by the executive director to estimate flash emissions. Computer simulationscan still 

### be used, but must be pre-approved by the executivedirector to make surethe simulationis used properly.

### HSC requested that 8115.116(a)(l)and (b)(l) be 

### ma& more stringentby changing the referenced vapor pressure from 1.0psia to 0.5 psia.

The requested change would affect 

### tanksin other nonattainment areas 

### than HGB. Because notice for the proposed rule indicated that the proposed changes would only apply to 

### tanks in the HGB 

### area, affectedowners and operators in other areasof the statehave not received proper notice of any changes that would affect their operations. Thus, the requested change is 

### beyond the scopeof the current rulemaking. 

### .

Dow and COMAQ suggested the removal of the word "reportable" from 51 15.1 16(a)(2)since the term "reportable" has other meanings in other portions of Texas air pollution regulations. The removal ofthe word "reportable" will clarify that the additional emissionsmust be included in the emissions inventory report and then either recorded or reported per the applicable existing provisions in 30 TAC Chapter 101(General Rules). TCC suggested revising §

### 115.116(a)(2) to change the term "reportable" to "emission inventory reportable" to clarify that emissions from secondary seal gaps arenot necessarily a reportable emission event as defined in Chapter 101, Subchapter

### F.

The commissionhas changed the term "reportable" to "emissions inventory reportable"


### as suggested.

CEMA suggested that languagebe added to the rule that acknowledges the option for facility operators to use internal combustionengine (ICE) based VOC oxidation systems to prevent an unfair market advantage for the controltechnologies listed in Chapter 115despite equal or better performance by ICE-based equipment. CEMA suggested revising the rule language in

### 5115.116(a)(3) and (b)(3) and 

### 5115.546(2) to include a section that reads "the output voltage of the engine exhaust oxygen sensor and the inlet and outlet gas temperature of the catalytic converter on an internal combustion engine."
The language in the rules does not specifynor exclude the use of any particular control technology 

### as long 

### as it achievesthe required 

### 90%reduction. The referenced rule sections donot 

### list monitoringrequirements for 

### all possibletypes of control. Moreover, the suggestedmonitoringlanguage for ICE equipment would not be sufficientto insure that theICE system is functioningproperly. For example, 

### PBR 5106.533(g)(4) for remediation requiresthat owners oroperatorsof ICE systems conduct an evaluation of engine effectivenessinitially and at least weekly, using a photo ionization detector (PID) or flame ionization detector (FID) in conjunction with a flow meter to determinethe quantity of carbon compounds

### in the inlet gas stream and the engine exhaust. The 

### FID or 

### PID instrument chosen must be capableofproperly detecting the types of contaminants present. For thesereasons, no changeshave been made to the rule languagein response to the comment, but the absenceof specific mention in the rule does not exclude the use of ICEbased equipment.



### GHASP suggested that the owners and operators offacilitiessubject to the monitoring and recordkeeping requirements in 

### 5115.116be required to report theirperformance parameters and efficiency calculations because the public needs the opportunity to monitor these facilities.

Facilities

### with Title 

### V operatingpermits under 30 TAC Chapter 122arerequired to submit 

### annual reports stating whether they arein compliance with 

### all applicable requirements, which would include rules in Chapter 

### 115. 

### Owners or operators must alsosubmit deviationreports for each six-month period if there have been deviationsin permit terms or conditionsduring the period. The public can obtain copies of these reports (minus any confidential data) from TCEQ. TCEQ investigators

### can also request that monitored data or calculationsbe reported.



### EPA recommended that each requirement for a two-year record retention time, including those in $115.116(a)(S)and (b)(5),be changed to require a five-year record retention time, consistent with Title 

### V and 30 TAC Chapter 122requirements.

The commissionhas not made the suggested change. Facilities

### with Title 

### V permits are required to retain records for five years under Title 

### V and 

### 30 TAC Chapter 122, regardless of the specifiedretention time in a specific rule. The requirements ip §115.116(a)(5) and (b)(5) apply to sourcesoutside the 

### HGB nonattainmentarea. Thus, no changescan be made tothese requirementsatthis time because public notice for the rulemaking indicatedthat the rule changes would apply only to sourcesin the 

### HGB area.

HSC requested that $115.116(c)(l)be made more stringent by changing 40,000 gallons and 25,000 gallons to 10,000.

The purpose of the recordkeepingrequirement 

### in §115.116(~)(1) is to require owners and operatorsto 

### maintain records documenting that the materials stored in 

### tanks that are not equipped with controls as specified 

### in Table I(a) or Table II(a) of §115.112(a)(l) have vapor pressures low enough to be stored without controls. As noted in responseto other comments, the commissionhas chosen not to change the 

### sizethreshold at which 

### tanks would be subject to controls to 10,000 gallons.Dow and TCC suggested deleting the recordkeeping requirements in $115.116(c)(l) since the regulated entity is already required to report this information through the Title 

### V Operating Permits program. The TCC also suggestedthat if $115.116(c)(l)is not deleted, then the commission should clarify the phrase "length of time the material is stored" to indicate if the phrase refers to the date the 

### tank is placed into service,the period of time it takes the 

### tank to turnover, or the period of time that the liquid material lies in the 

### tank while the roof is resting
on its legs.

The commission has maintained the referenced recordkeepingrequirement to ensure that
owners and operators have appropriate, current, readily available records to allow investigatorsto verify that materials stored in uncontrolled 

### tanks have vapor pressures low enough to be stored without controls. Recordsin Title 

### V operating permits 

### may only refer to material safety 

### data sheetsthat 

### list a range of vapor pressures for 

### an ill-defmed material (such as bunker oil). The actual vapor pressure of such materials can vary with different suppliers, different shipments, or different production runs. Results of remote sensing studieshave shown unexpected 

### VOC emissions from fmed-roof storage 

### tanks that storematerials with reportedly low vapor pressures. The commission has revised the languagein $115.116(c)(l) to specify that the "length of time the material is stored" refers to the starting and ending dates that a material is or has been in the 

### tank.

HSC requested that $115.116(~)(2) be made more stringentby changing the referenced emission level from 25 tpy to 10 tpy.

The purpose of the recordkeepingrequirement in $115.116(~)(2) is to document that emissionsfrom

### tanks not equipped with controls for flash emissions arebelow the level atwhich control is required. As discussed

### in response to other comments, the commission has chosen not to changethe level from 25tpy to 10 tpy. 

### Since the level has not changed, it would be inappropriateto revise this recordkeepingrequirement.

The TCC suggestedrevising 

### 5115.116(c)(2)to read "the owner or operator of any Exploration and Production storagevessel 

## ... shall maintain records 

## ...The records must be updated annually and must be made available for review 

### as soon as possible upon request." The TCC suggested the commissionuse the "maximum authorized emission rate" to satisfy the "projected emissions" requirement, rather than requiring the owner or operator of an Explorationand Production storage vessel to speculate within the context ofthe rule on the projected 

### tank emissions for the next year of operations.

The commission has revised §115.116(~)(2) to specify that therecordkeepingrequirement applies only to crude oil and condensate stored prior to custody transfer or at midstream pipeline breakout stations. The commission agreesthat the maximumauthorized emission rate, if calculated to correctly account for flash emissions, 

### can be used to document that emissions are lessthan the 25 tpy threshold for control and has deletedthe requirement to project emissions for the next year.

HSC requested that the rule be made more stringentby changing 1.5psia to 0.5 psia in 5115.117(a)(l)andby changing 25,000 gallons to 10,000gallons in 5115.117(a)(3).

Asnoted 

### in responsetoearlier comments, the commissionhas decided to 

### maintain the exemption levels at 1.5 psia and25,000 gallons.

### HSC requested that the rule be 

### made more stringentby changing 1.5 psia to 0.5 psia in $115.117(b)(l) and (c)(l),by eliminating the exemption in $115.117(b)(2), by changing 25,000 gallons to 10,000 gallons in $1 15.117(b)(3)and (c)(3), and changing420,000 gallons to 10,000 gallons in @

### 115.117(c)(4).
The requested changes affect subsectionsthat were not opened in the current rulemaking. These subsectionsaffect sources outsidethe 

### HGBeight-hour ozone nonattainment 

### area. Owners and operators of these sources have not been given proper notice of proposed changes and would not have an opportunityto comment. Thus, making the suggested changes is beyond the scope of the current rulemaking.



### GHASP suggested eliminating the exemptions for 

### tanksconstructed prior to 1980and 

### 1982and requiring the installation of appropriaterim mounted secondary seals for external floating roof tanks. 

### In instances where upgrading the tanks is not technologically feasible, GHASP suggested that those 

### tanks should be relegated to service with liquids with vapor pressures less than 

### 0.5 psia, or service exempt from NSPS Subpart

### Kb.

The commission did not propose substantivechanges to the referenced exemptions in §115.117(4), 

### (6),or 

### (7).Making changes at 

### this time is thus beyond the scopeof the current rulemakingbecause it would impose controls on owners or operators who have not received proper notice of additionalregulatory requirements and would not have an opportunityto comment. The commission may consider eliminatingthese exemptions 

### in a future rulemaking.The EPA requested confirmation that credit for this rule has been appropriately prorated to reflectthe extended time period allowed for compliance.
The purpose of the rule was toreduce VOC emissionsthat have been previously unreported or underreported in the 

### EI. For this reason, the commission has not taken credit for emissions reductionsfromthis rule.

The EPA requested confinnationthat the new rule includes all componentsneeded for enforcementpurposes. 

### In particular, the EPA noted that if compliance with the rule would necessitateemptying and degassing the tank, compliance would not be required until the next time the 

### tank is emptied and degassed but not later than January 1, 2017. The EPA asked the commissionto consider whether existing reporting requirements are sufficientto allow inspectorsto verify the most recent date a 

### tankwas emptied and degassed and to add reporting requirements if necessary to provide for enforceability of the rule.

Commissiongeneral 

### air quality rules in 

### 30 TAC 

### $101.201(b)require owners or operators to

### maintain records of scheduledmaintenance activities, which would include 

### tank degassing and cleaning. No changes were made to therule as a result of this comment.
COMAQ suggestedthat TCEQ reconsider its position in §115.119(c) that the required control equipment could be put into place without 

### tanks having to be taken out of service, citing that COMAQ members' experience has been that any significant work on 

### tank roof fittings and seal systems requires tank de-inventory and degassing in order to prevent unacceptableLEL readings and personnel safety concerns.

### The commission maintainsthat certain types of roof fittings and controls for slotted guidepolescan be installed without taking the tank out of service. However, the rule languagein 0115.119(c) states that compliancecan be delayed beyond January 1,2009, until the next time the 

### tank is 

### emptied and degassed if compliant equipment cannot be installed without taking the 

### tank out of service. The decision whether equipment can be safely installed without taking the tank 

### out of service will 

### be made by the owner or operator. The rule does not give specific requirementsfor proving that the installation cannotbe safely performed while the tank 

### is in service, but the owner or operator should document and maintain for inspection purposesthe rationalefor delayed compliance.
Dow supportsthe TCEQ's consideration that storagevessels will have to be 

### degassed and emptied to comply with 

### 4 115.112(d)requirements, and suggested editing 

### 5115.119(c)to clarify that compliance with 

### 44 115.112(d), 115.115(c), and 115.116(c) is not required until the next scheduled emptying and degassingactivity after January 1,2009.

The commissionappreciatesthe support, but does not agreethat compliance 

### is not required until the next scheduled emptying and degassing activity after January 1,2009. The reason for allowing the delay of complianceis 

### to avoid requiring that a tank be taken out ofservice and degassed solely for the purpose of complying with the new requirements. In some cases, the emissionsthat would 

### occur from the degassing activity (even when complyingwith 

### the revised requirements for degassing in Chapter 115, Subchapter

### F) would be greater than emissionsthat would be 

### reduced by installing compliant equipment. For 

### tanksthat will 

### be emptied and degassed after the date the rule becomes effectivebut prior to January 1,2009, the commission expects that equipment required tocomply with the revised rules can be 

### installed atthat time, even though

### compliance 

### is not required untilJanuary 1, 2009. 

### Ownersand operators who are planning tank 

### emptying and degassing activities should plan ahead to install

### compliant equipment at the next opportunity.

EPA noted that the preamble discussion for 

### 5 115.119(c) states, "The commissionanticipates that most, if not all, of the required control equipment can be put intoplace without taking the tank out of service," and requested that the commission consider modifying the rule to require that most, if not all, of the components in the rules be met by January 1, 2009.


### Industry commentersdisagree with 

### the commission's statement that most required control equipment can be put into place without taking a 

### tank out of service. Therule language statesthat compliance must be achieved by January 1,2009, 

### unless compliance would require emptying and degassingthe storage 

### tank. A 

### further requirement that 

### "most"of the componentsin the rules be met by January 1,2009, 

### would be unenforceable.

HSC objected to delayed compliance for tanks that must be emptied and degassed to install controls, since degassing is controlled, and stated that exceptions to not emptying a tank for installationof controls should only be allowed based on a petition from a regulated entity that demonstrates that emissions from emptying and degassing cannot be controlled and that the tank must be emptied to install the controls. GHASP commented that the storage tank regulations in Chapter 115 should mandate complianceby all affected facilitiesby January 1, 2009. GHASP stated that operating practices can be modified to eliminate convenience landings and that if a facility chooses 

### to install controlsthat require emptying the tank, operating practices 

### can be modified until the tank maintenance is undertaken.In some cases, the emissionsthat would occur from the degassing activity (even when complying with the revised requirementsfor degassing in Chapter 115, Subchapter 

### F) would be greater than emissionsthat would be reduced by installing compliant equipment. Due to the high cost effectivenessof requiring degassing controls on small

### tanks, the commission has revised the new degassingcontrol requirements to apply only to 

### tanks with nominal capacity greater than or equal to 250,000 gallons or to tanks with nominal capacity greater than or equal to 75,000 gallons storing materialwith vapor pressure greater than 2.6 psia. If degassing is not controlled, emissions from takingthe tank out of serviceto install controls could negate the environmentalbenefit of the controls. The provision for delayed complianceis not anticipated to affect the compliance date for 

### tank landings, since facilitiescan comply with the requirementsby changes in operational practices, as noted by the commenter.



### HSC requested that the control requirements for VOC loading operations in 5115.212 be 

### revised to require a controlefficiency of 95% 

### rather than 

### 90%.

The requested change is beyond the scopeofthe current rulemaking, since no changes were proposed to 5115.212. Staff consideredthis changeto loadingrequirements 

### as the rule proposal

### was being developed. Accordingto available 

### data in the EI, most of the control devices 

### in use were already reducingemissionsby 95% or more. 

### Also, emissions from controlled loading operations represent a 

### small fractionof the total 

### VOC from point
sources in the HGB 

### area. Thus, making this change would result 

### in only minimal emissions reductions.RSI suggestedthe commission examine the upcoming South Coast Air Quality Management District (SCAQMD) tank degassing regulations.

The commission has reviewed the existing SCAQMDregulationson tank degassing and commission staff has discussedupcoming changes with SCAQMD staff.

GEM suggested degassing companies be required 

### to provide notificationof degassing activities if onsite inspections of 

### tank degassing is going to be implemented.

The commission requires notification of scheduledmaintenance activitiessuch as 

### tank degassing if expected emissionswill exceed 

### a reportable quantity 

### as defined in 30 TAC $101.1. A specific notification requirement may be considered 

### in a future rulemaking.

The TCC suggested the commission confirmin $115.541that if a covered 

### tank is flooded with
a diluent that has a true vapor pressure of less than 0.50psia then the control requirements of this subchapter are no longer applicable.

The commission does not agree that 

### flooding a 

### tank with a low vapor pressure diluent automaticallynegatesthe applicability of control requirements of Subchapter 

### F. Pockets of material with a higher vapor pressure

### may be present in sludge on the 

### tank bottom and be unaffected by the use of the diluent. 

### Use of a diluent would 

### also create a mixture that would presumablybe a waste that could cause additional VOC emissions when disposed.
COMAQ suggested the emission specificationsand control requirements for the degassing of storage tanks with a nominal capacity between 40,000 and 

### 1million gallons should not be

### included in 51 15.54,1(a)(l) and $115.547(2). 

### COMAQ states that the 40,000 gallon threshold
was arbitrarily chosen by the commission and does not take into account the quantity of emissions from the degassing process or the economic feasibilityof installing the controls. TCC commented that the minimum cost for complying with the degassing requirements would be 

### $5,000 and suggested revising the degassing emission specifications applicability threshold in $

### 115.541from 40,000 gallons to 250,000 gallons. HSC 

### requested that the rule be 

### made more stringentby changing 40,000 gallons to 10,000 gallons in $115.541(a)(l)and $115.547(2).

Emission reductionsthat 

### can be realizedby requiring controlled degassing decrease asthe size of the 

### tank (and, thus, the amount of vapor space saturated with VOC) decreases. Controlof degassing emissionsis generally carried out by outsidecontractors who bring equipmentto the site. The charge for bringing in and operating the equipment 

### is generally the same regardlessof the size of the 

### tankto be degassed. Thus, the cost effectivenessfor controlling degassing emissionsfor 

### tanksas

### small as 10,000 gallons is much higher than for larger 

### tanks. The commission does not believe that the cost for controlling degassing emissions from these smaller 

### tanks isjustified. As noted by TCC, the cost effectiveness for controlling degassing emissionsfrom a 40,000 gallon 

### tank storinga material with a vapor pressureof 0.5 psia would be greater than $60,000 per ton of VOC removed. The commission has estimatedthat the cost effectivenessof controlling degassingemissions from tanks 

### with tapacity of 250,000 gallons storingmaterials 

### with a vapor pressure of 0.5 psia or higher would be less than $12,000 per ton. The cost effectivenessfor requiring degassing controls increases for smaller 

### tanks and would exceed the $12,000 per ton value that is used in evaluatingBACT. Thus, the commissionhas revisedthe applicability threshold 

### to 250,000 gallons for 

### tanksstoring materialswith vapor pressures down to 0.5 

### psia. However, smaller 

### tanksstoring more volatile materialswould have higher emissionsand lower cost effectiveness. Regulations applicable in the SCAQMDtake the higher emission potential into accountby requiring degassingcontrolsfor 

### tanks as 

### small as 19,815gallons storing materials with a vapor pressure greater than 3.9 psia, and for tanks
as 

### small as 39,630 gallons storing materials with a vapor pressure greater than 

### 2.6 psia. Commissionstaffestimated the cost effectivenessto controldegassingemissions from tanks with a range of sizes and vapor pressures of stored liquid, and concluded that the cost effectiveness to control degassing emissions from 

### tanks 75,000 gallonsor larger storing materials 

### with vapor pressure greater than 2.6 psia was appreximately $20,000 per ton or less. The commissionhas revised the rule to require degassing control for 

### tanks with a capacity of 250,000 gallonsor more, and for 

### tanks with capacity of 75,000 gallons to 250,000 gallons storing material with vapor pressure greater than 2.6 psia.

HSC additionally requested that the rule be made more stringentby changing 8,000gallons to 5,000 gallons in $115.541(a)(2) and by changing 420,000 gallons to 10,000gallons in $115.541(b)and $115.547(2).

The commenter gives no basis to support the requested changes. The rule proposal did not include a change in the size of transport ormarine vessel that would be required to control degassing emissions. Thus, the requested change 

### is beyond the scope of the current rulemaking.

HSC requested that the rule be made more stringentby changing 90%to 95% in $115.541(a)(l)(B)and (a)(2)(B) and in $ 115.541(b)(2).The commission made no changes to the rule in response to 

### this comment. The focus of the rulemaking project was to effect real reductions in 

### VOC emissions. Although the rule only requires a controlefficiency of 90%, many of the control devices 

### in use in fact reduce emissionsby 95% or more.



### GEM suggested if the four vapor space turnover requirement remains part of the degassing rule then the commission should require that approved inlet vapor flow meters be 

### installed at the inlet of the control device to help standardize the flow volume measurement.

The commissionhas deleted the turnover requirement for affected sourcesin the HGB after January 1,2009. The four vapor spaceturnover provision remainsin effect for sources in the BPA nonattainment 

### area, but changes that would affect sources in 

### this area
are beyond the scopeof the current rulemaking since public notice indicated that rule changes were only being made for sources in the HGB area.



### HSC requested that the rule be 

### made more stringentby changing 34,000

### ppmv to 10,000ppmv in 

### 0115.542(a)(2) and (b)(5).

The purpose of the proposed rule was to change the method for demonstratingwhen sufficient degassing had occurred, not changingthe required level. The 34,000 ppmv level is based on requiring degassingcontrol down to an equivalentpartial pressure of 0.5 psia: 0.5/14.7*1,000,000 = 34,000 ppmv. Because no changeto this level was proposed, loweringit is beyond the scope of this rulemaking.HSC requested that the rule be made more stringentby changing 34,000ppmv to 10,000ppmv in $115.542(b)(4) and by eliminating the words "a turnover of at least four vapor space volumeshas occurred, the partial vapor pressure is less than 0.5 psia (19,000ppmw) 

### ... or the concentration of VOC is less than 

### 20%of the lower explosivelimit."


### The requirementsin §115.542(b)(4) apply to sources in the Beaumont-Port Arthur (BPA) and untilJanuary 1,2009, in the HGB area. No changes affectingsources in BPA were proposed; thus, making the requested change is 

### beyond the scope of the current rulemaking. The regulated community must have time to implementnew rule requirements; thus, the current wording 

### is necessary to 

### maintainthe applicabilityof the erdsting requirementsin HGB until the compliance

### date for the new requirements.
COMAQ requests that the TCEQ clarify whether "ventilated," "ventilation," and "vented"
mean forced ventilation only, or both forced and passive ventilation as used in §115.542(a)(6). In this same section, the TCC suggested clarifying the intent of the phrase "before dilution."



### The commissionhas revised the rule language to 

### use the 

### term "vented to the atmosphere" for clarity. The commissionhas removed the word "before dilution" from the rule language as requested. The intent of the phrase "before dilution" was to emphasizethat vapors arenot to be released to the atmosphere untreated because 

### an excessivevolume of ventilation gas is 

### used. Depending on the type of controltechnology used to abate the degassingemissions, dilution gas is sometimesnecessary to 

### maintain safe conditionsin the abatement device. The concentrationmeasurement shouldbe made before the dilution gas 

### is added.TxOGA expressed general support for $115.542 stating that the use of vapor concentration rather than turnover volume for determinationof sufficientprocessing of vapors provides operational consistency during 

### tankdegassing. TxOGA suggested that the LEL is a better threshold for determining compliance than the ppmv or ppmw determinationand suggested that $115.542(a)(5) and (6) be changed to add "50%LEL" as a criteria for determining when vapors can be released to atmosphereinstead of the 34,000ppmv concentration limit.

The commission agrees that a 

### VOC concentration equivalent to 50%

### LEL will be lower than the 34,000 ppmv concentration criteria and 

### so has made the requested change in §115.542(6). The commissionhas not made the suggested change in §115.542(a)(5) because this provision applies to sources 

### in the 

### BPA nonattainment area 

### as well as to the 

### HGB area until January 1,2009. Because notice for the current rulemakingindicatedthat changes
were being made only for the 

### HGB 

### area, changingthe provision applicable to 

### BPA is beyond the scopeof the current rulemaking.

Dow, TCC, and COMAQ suggested revising the periodic measurements required to confirm that the VOC concentration is less that 34,000ppmv 

### in $115.542(a)(6) and (b)(5). The commenters suggested that three consecutivereadings, each taken at a 12-hour interval, with a VOC concentration less than 34,000ppmv during ventilation is adequate to confirm that the VOC concentration is not varying significantly and that further checks every 12hours are not warranted.

The commissionagrees that concentrationmeasurementscan be ceased at some point 

### in the degassing and cleaning process but is concerned that if sludgeremains in the 

### tankafter the initial degassing, 

### VOC concentrations could decrease to less than 34,000 ppmv butlater increase when the sludge 

### is disturbed during the cleaning process. The commission has changed the rule to specify that concentration measurements 

### can be discontinued after five consecutivereadings less than 34,000 ppmv. With readings taken every 12hours, the five readings would provide that the concentration would remain below 34,000 ppmv for at least 

### 48 hours. VOC emissionsassociated with the removal of sludge from the 

### tank may need to be recorded and reported under the maintenancerules in 30 TAC Chapter 101.

The TCC suggested revising $115.541(a)(l) and $115.542(a)(5)to allow a delay in compliance until the next time the vessel is emptied but no later than January 1, 2017, if compliancewould require the installationof degassing nozzles or connections. However, if appropriate degassing nozzles can be added by changing out a rnanway, the TCC suggested the commission should consider revising $115.542(a)(5)to allow a rnanway to be opened for the shortperiod of time necessary to change-outthe manway to one with the appropriatenozzles.

The commission does not agree that a delay in compliance is necessary for 

### tanks that must have degassingnozzles or connections installed. Hatches with nozzles installed can be obtained for newly-affected 

### tanks. The commission has not revised $115.542(a)(5) to specificaUy allow the manway opening. Maintenance activitiessuch 

### as manway opening
are subjectto an affirmative defense aslong as they comply with the general rules for maintenance

### in 30 TAC Chapter 101.

The TCC suggested that $115.542(b)(5)be revised by adding the phrase "of the degassing operation. "

The commissionhas

### made the suggested change.
70TTO expressed support for the 34,000ppmv trigger for controlling vapors during tank degassing but requested clarification that sampling to obtain VOC concentration measurements during degassing does not require tank entry and VOC concentration measurements can be taken from a tank's rnanway. TxOGA suggested that the preamble language regarding the frequency and method for measurement of VOC concentrations in $115.545(11)be modified to read "the measurement should be made at the head space of the vessel, as close as possible to the tank bottom to ensure that the concentration measurement is representative of actual conditions. However, these measurements are to be taken at locations that do not endanger the safety of sampling personnel."



### The commission did not intend that VOC measurementsbe made inside the 

### tank or other location that would endanger the safety of sampling personnd.
COMAQ, Dow, GEM, TCC, TTO, and TxOGA suggested the agency allow acceptable alternatetest methods for VOC concentration measurements specified in $115.545(11). The suggestedmethods include EPA Method 25A; EPA Method 18, adjusted to allow for one bag sampleto be collected; bag sampling; portable hydrocarbon gas analyzer; PID; chemical specific detection tubes; and LEL meters. COMAQ commented that FIDs are not appropriate for testing VOC in nitrogen-rich, oxygen-poor atmospheres because the FID will "flame out. " Dow suggested that measurement of the total organic carbon (TOC) content of the condensate streambe allowed for vessels that are degassed and cleaned via steam.



### The commission 

### agrees that additionalmethodsfor measuringthe VOC concentration would be acceptableand has revised the rule accordingly. The commission does not agree that chemical specific detection tubes are appropriate because they are usually compound
71specific and could result in falsenegatives. Also, the detection tubesmight be diflicult to operate in the 

### tank degassing environment. The commission does not agree that measurement of the TOC content of the condensate 

### stream would be an appropriate indication of the VOC concentration of the vapor space. Even if an accurate correlation between the TOC concentrationof the condensate and the VOC in the vapor space could be determined, use of this method would require the TCEQ 

### staff to review and approve the correlationbefore it could be used. Tank degassing events are episodic and of short duration; approval of a correlationmight not be possible in time for it to be used.

Dow and TCC suggestedthat the TCEQ clarify that the instrument response factor criteria in $8.1 of EPA Method 21 be for the averagecomposition of the liquid in the tank, transport vessel, or marine vessel and not for each individual VOC in the liquid. Dow noted that this approach is consistent with EPA's HON regulation in 40 

### CFR $63.180(b)(2)(i).

The commission 

### agrees that use of the average composition of the tank contentsto determinethe instrument response factor

### is appropriate and has revised the rule accordingly.



### RSI suggested that the protocol for sampling and analyzing must be clearly defined so that enforcementdoes not have to merely assume that measurements are being done correctly.

The commission has listed approvedtesting methods in 3115.545(11) in order to ensure that measurements arebeing performed correctly.COMAQ suggested including an exemption from the emissions specifications and control requirementsif the tank owner or operator can demonstrate compliance would be economically unreasonable by revising $115.547(2) to read "degassing and cleaning 

## ...any stationary VOC storagetank with a nominal storagecapacity of less than one million gallons, or any marine vessel, with a nominal storage capacity of less than 10,000barrels (420,000 gallons), is exempt from the requirements of this division. 

### In addition, a tank is exempt from the requirements of this division if its owner or operator can demonstrate to the satisfaction of the executive director that compliance with the requirements of this divisionwould be economically unreasonable."

The commission does not agree that an exemption shouldbe allowed for individual 

### tanks based on whether control is "economically unreasonable." The rules 

### in Chapter 

### 115must meet the standards that the EPA 

### has set for reasonably available control technology (RACT). The EPA definition of RACT is "the lowest emission limitation that a particular
source can meet by applying a control technique that is reasonably available considering technologicaland economic feasibility." The standard is economic feasibility, not economic reasonableness. With the revised applicability levels in the adopted rule based on 

### tank size and vapor pressure of storedmaterial, the commission

### maintainsthat control of degassing emissions from all affected 

### tanks is economicallyreasonable as well astechnically and economicallyfeasible.

RSI commented that calculating the destruction rate efficiency of abatement devices used to control emissions from the tank degassing process is not easily defined. Knowing the influent concentration in ppmv makes logical sense for determining when a tank degassing event is finished but in order to determine the allowable emissions it is necessary to also know the flow rate of the effluent in cubic feet per minute.The degassing rules do not require a calculation of allowableemissionsfrom abatement devices. Thus, no changes havebeen made tothe rule in response to this comment.



### RSI expressed concern that their ICE technology, with destruction efficiency greater than 99.9%,will be priced out of the market in Texasbecause these rules only require a destruction efficiency of 90%

## .

The commissionhas made no change to the rules as a result of this comment. Even though the rule only specifies

### 90%destruction efficiency, other concernsmay drive regulated entitiesto use more efficient control equipment. When degassingoperationsare carried out 

### as 

### part of maintenanceactivities, emissions

### must be minimized under the requirements of the general air quality rules 

### in 30 TAC Chapter 101. Emissions from planned maintenanceactivitiesmust be authorized under 30 TAC Chapters 106 or 116 according to the schedule in 30 TAC 5101.222. Authorization will require 

### use of BACT, which could require more stringent controlthan the 

### minimum specified 

### in 30 TAC 0115.541.

TxOGA expressed support for a portable equipmentregistration or certificationprogram for vendors or contractors who provide degassing equipment that would certify that the vendor degassing equipment meets TCEQ emission standards and ensure that contractorproviding the portable equipment understands TCEQ rules and documentation requirements.
Establishing a registration or certificationprogram for degassing vendors or contractors is beyond the scope ofthe current rulemaking, but the commission may consider 

### such a program 

### in the future.HSC requested that the exemptionfor oceangoing, self-propelled marine vessels in 

### 5 115.547(5) be removed so that these vessels must be degassed and cleaned when they have emptied their VOC cargo.



### The commission did not provide notice of any change 

### to the referencedexemption for oceangoing, self-propelledmarine vessels. Thus, proper notice to the owners and operators of such vessels has not been given and 

### makingthe requested change is beyond the scope of the current rulemaking. The commissionmay consider a change to this exemptionin futurerulemaking.