TECHNICAL SUPPORT DOCUMENT

30 TAC, Chapter 117 Control of Air Pollution from Nitrogen Compounds

Lean-Burn Engines Fired on Biogas in the DFW Ozone Nonattainment Area

Rule Project No 2010-048-117-EN

EPA-R06-OAR-2011-0494

And

30 TAC, Chapter 117 Control of Air Pollution from Nitrogen Compounds

Exemption of the Low Temperature Drying and Curing Ovens in the DFW Ozone 

Nonattainment Area

Rule Project No 2009-023-117-EN

EPA-R06-OAR-2011-0494
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This Technical Support Document (TSD) is comprised of two separate sections 1 and 2.

Section 1 concerns our evaluation of Texas’ final rule adopted on April 20, 2011 as a revision to 

the Texas State Implementation Plan (SIP) concerning 30 TAC, Chapter 117 Control of Air 

Pollution from Nitrogen Compounds, Rule Project No 2010-048-117-EN. The submittal is 

determined to be administratively complete. See pages 1 through 4 of the completeness checklist 

prepared in conjunction with this rulemaking action.

Section 2 of the TSD concerns the our evaluation of Texas’ final rule adopted on January 13, 

2010 as a revision to the Texas State Implementation Plan (SIP) 30 TAC, Chapter 117 Control of 

Air Pollution from Nitrogen Compounds, Rule Project No Rule Project No 2009-023-117-EN. 

See pages 5 through 8 of this TSD. No material in either of these two SIP submittals was 

designated as Confidential Business Information.

Section 1 - Lean-Burn Engines Fired on Biogas in the DFW Ozone Nonattainment Area:

We received this SIP submittal package, with a letter dated May 18, 2011, from TCEQ

requesting approval of a revision to 30 TAC, Chapter 117, Subchapter D, Combustion Control at 

Minor Sources in Ozone Nonattainment Areas, Division 2, Dallas-Fort Worth (DFW) EightHour Ozone Nonattainment Area Minor Sources, Section 117.2110(a)(1)(B)(ii)(I). Rule 

identifiers information is as follows:

Rule Project No 2010-048-117-EN

Lean-Burn Engines fired on biogas in the DFW area (Ameresco). Minor Source Rulemaking 

Amendment to: §117.2110 

Date Adopted: April 20, 2011 

Date Filed with the Secretary of State: April 22, 2011 

Date Published in the Texas Register: May 6, 2011 

Date Effective at State Level: May 15, 2011 

TCEQ proposed this rule change following a petition from Ameresco of Texas. See 35 Texas 

Register 10162 published November 19, 2010. We originally approved the revisions to 30 TAC, 
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Chapter 117 Control of Air Pollution from Nitrogen Compounds on December 3, 2008 at 73 FR 

73562. The proposed text of the Section 117.2110 reads:
Page 4 of 14

§1l7.2110. Emission Specifications for Eight-Hour Attainment Demonstration.

(a) The owner or operator of any source subject to this division (relating to Dallas-Fort Worth 

Eight-Hour Ozone Nonattainment Area Minor Sources) shall not allow the discharge into the 

atmosphere emission of nitrogen oxides (NOx) in excess of the following emission 

specifications.

(1) Emission specification for stationary. gas-fired, reciprocating internal combustion 

engines are as follows:

(A) rich-burn engines:

(i) fired on landfill gas, 0.60 grams per horse power hour (g/hp-hr); and

(ii) all other rich-burn engines, 0.50 g/hp-hr; and

(B) lean-burn engines:

(i) placed into service before June I, 2007, that have not been modified, 

reconstructed. or relocated on or after June 1, 2007. 0.70 g/hp-hr; and 

(ii) placed into service, modified, reconstructed, or relocated on or after 

June 1. 2007:

(I) fired on landfill gas or other biogas 0.60 g/hp-hr; and

(II) all other lean-burn engines, 0.50 g/hp-hr.

(2) The emission specification for stationary, dual-fuel, reciprocating internal 

combustion engines is 5.83 g/hp-hr.

(3) Emission specification for stationary, diesel, reciprocating internal combustion 

engines are as follows:

(A) placed into service before March 1,2009, that have not been modified, 

reconstructed, or relocated on or after March 1, 2009, the lower of 11.0 g/hp-hr 

or the emission rate established by testing, monitoring, manufacturer's 

guarantee, or manufacturer's other data; and

(B) for engines not subject to subparagraph (A) of this paragraph:

(i) with a horsepower (hp) rating of 50 hp or greater, but less than 100 

bp, that are installed, modified, reconstructed, or relocated on or after 

March I, 2009, 3.3 g/hp-hr;

(ii) with a horsepower rating of 100 hp or greater, but less than or equal 

to 750 hp, that are installed, modified, reconstructed, or relocated on or 

after March I, 2009, 2.8 g/hp-hr; and

(iii) with a horsepower rating of 750 hp or greater that are installed, 

modified, reconstructed, or relocated on or after March I, 2009, 4.5 

g/hp-hr.

(4) As an alternative to the emission specifications in paragraphs (1) - (3) of this 

subsection for units with an annual capacity factor of 0.0383 or less, 0.060 pound per 

million British thermal units (lb/MMBtu) [lb/MMBtu] heat input For units placed into 

service on or before December 31, 2000, the annual capacity factor as of December

31, 2000, must be used to determine eligibility for the alternative emission specification 

of this paragraph. For writs placed into service after December 31, 2000, a 12-month 

rolling average must be used to determine the annual capacity factor.
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As it can be seen section 117.2110(a)(1)(B)(ii)(I) will now read: “(I) fired on landfill gas or other 

biogas 0.60 g/hp-hr;” The term “or other biogas” has been added to this subsection. 

In our comment letter dated December 16, 2010 we wrote: 

“Under the existing rules, the lean-burn engines would be held to 0.50 g/hp-hr NOx emission 

limits. Under the proposed rule, the engines would be limited to 0.60 g/hp-hr of NOx. Under the 

proposed rules, you have projected that 0.02 tons per day more NOx emissions would be allowed 

compared to the existing NOx rules.”

In their SIP narrative section titled “Evaluation” TCEQ wrote that a larger amount of NOx could 

otherwise result, if a likely alternative such as routing the gas to a flare is utilized. Under this 

project the biogas will be used beneficially. Engines fired on landfill gas and other biogas can 

have technological feasibility issues with regard to the installation or employment of a NOx 

control catalyst due to presence of contaminants such as sulfur, chlorine, and silicon which can 

contribute to catalyst failure or deactivation in a matter of hours or days. By adopting this 

revision the emission specifications for this category of engines in the DFW area will become 

consistent with the emission specification for this category of engines operating in the HoustonGalveston-Brazoria (HGB) 1997 8-hour ozone nonattainment area. The revision will provide for 

consistency and operational flexibility for this category of engines operating in the DFW 1997 

eight-hour ozone nonattainment area. Furthermore, TCEQ is reporting in excess of 7 tpd of 

surplus NOx reductions (under a conservative estimate scenario) for the DFW area from its 

mobile sources (fleet turnover) that would more than compensate the 0.02 tpd increase associated 

with the biogas project. The fleet turnover surplus is documented in Table 4.3 of the DFW 1997 

8-Hour ozone nonattainment area plan TCEQ Project No. 2009-021-SIP-NR, that the State 

adopted on March 10, 2010. See Table 4.3 of that document below.
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Section 110(l) analysis:

In the 36 Texas Register 2856 issue dated May 10, 2011 TCEQ wrote “The commission provides 

the following information to demonstrate why the adopted change to expand the emission 

specification in §117.2110(a)(1)(B)(ii)(I) will not negatively impact the status of the state's 

attainment with the 1997 eight-hour ozone National Ambient Air Quality Standard (NAAQS), 

will not interfere with control measures, and will not prevent reasonable further progress toward 

attainment of the ozone NAAQS. The commission acknowledges that the DFW area failed to 

attain the 1997 eight-hour ozone NAAQS by the June 15, 2010, attainment deadline based on 

monitoring data; however, the adopted rule change will not adversely affect the ability of the 

DFW area to attain the 1997 eight-hour ozone NAAQS for the reasons discussed in this 

preamble. The requirement for reasonable notice and public hearing was satisfied through a 

public hearing scheduled for December 14, 2010, and the public comment period, held 

November 19, 2010, to December 20, 2010. The purpose of the hearing was to accept written 

and oral comments on the proposed rulemaking. A written comment was submitted by the EPA. 

The EPA stated their agreement with the commission's §110(1) determination that the proposed 

rulemaking will not interfere with attainment or maintenance of the 1997 eight-hour ozone 

NAAQS in the DFW area. On May 23, 2007, as part of the DFW attainment demonstration, the 

commission adopted a new Chapter 117, Subchapter D, Division 2 with new emission control 

requirements for minor industrial, commercial, or institutional sources of NOx in the DFW 1997 
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eight-hour ozone nonattainment area. Subchapter D, Division 2 requires owners or operators of 

minor sources of NOx in the DFW 1997 eight-hour ozone nonattainment area to reduce NOx 

emissions from affected stationary internal combustion engines. A minor source of NOx in the 

DFW 1997 eight-hour ozone nonattainment area is any stationary source, or group of sources 

located within a contiguous area and under common control that emits or has the potential to 

emit less than 50 tons per year of NOx. One source category newly regulated under Chapter 117 

during the 2007 rulemaking was lean-bum engines at minor sources. The current applicable NOx

emission specification in 117.2110(a)(1)(B)(ii)(II) for gas-fired, lean-bum engines using gaseous 

fuels other than landfill gas that are installed, modified, reconstructed, or relocated on or after 

June 1, 2007, is 0.50 g/hp-hr. During the 2007 rulemaking, no landfill gas-fired engines were 

identified in the emissions inventory in the counties impacted by the proposed rule; however, the 

emission specification of 0.60 g/hp-hr for gas-fired engines fired on landfill gas established by 

§117.2110(a)(1)(B)(ii)(I) is consistent with the emission specification for this category of 

engines in the Houston- Galveston-Brazoria 1997 eight-hour ozone nonattainment area. In the 

2007 Chapter 117 rulemaking for the DFW1997 eight-hour ozone attainment demonstration, no 

gas-fired engines fired on biogas or other non-landfill gaseous fuels were relied upon for 

creditable reductions for the SIP. Therefore, if the petitioner's proposed change is adopted, 

allowing the slightly higher emission specification of 0.60 g/hp-hr on gas-fired engines fired on 

other biogas fuels would not result in a loss of any SIP creditable reductions for the DFW 1997 

eight-hour ozone nonattainment area. The adopted change is limited to a narrow category of 

stationary gas-fired engines with NOx controls that were not relied upon in the DFW 1997 eighthour ozone attainment demonstration adopted in 2007, and the resulting change in future NOx

emissions is negligible. Furthermore, if the rulemaking is not adopted and the petitioner is not 
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able to comply with the 0.50 g/hp-hr emission limit or purchase credits to offset the surplus 

emissions, the petitioner may be forced to abandon the project. This outcome could actually 

result in a net NOx emissions increase that is more than the 0.02 tons per day increase 

anticipated if the rule is adopted. If the company is forced to send the emission stream to a flare 

for destruction rather than use the stream as a fuel source in the engines, the total uncontrolled 

NOx emissions could exceed that of the controlled emissions under the proposed emission limit, 

because flares are exempt from NOx emission limits under Chapter 117. Based on these factors, 

the commission has determined that the adopted rule change will not negatively impact the status 

of the state's attainment demonstration for the 1997 eight-hour ozone NAAQS, will not interfere 

with control measures, and will not prevent reasonable further progress toward attainment of the 

ozone NAAQS.” The graph below illustrates this comparison.
Page 9 of 14

For these reasons we find the rule revision acceptable for approvability purposes and believe this 

revision will not be in conflict with Section 110(l) of the Act, and will not interfere with the 

attainment or maintenance of the NAAQS. Therefore, we find that the revision meets the 

applicable requirements of the CAA and EPA air quality regulations.

Section 2 - Exemption of the Low Temperature Drying and Curing Ovens in the DFW 

Ozone Nonattainment Area:

As stated earlier, section 2 of the TSD concerns our evaluation of Texas’ final rule adopted on 

January 13, 2010 as a revision to the Texas State Implementation Plan (SIP) concerning 30 TAC, 

Chapter 117 Control of Air Pollution from Nitrogen Compounds, Rule Project No Rule Project 

No 2009-023-117-EN. We received this SIP submittal package, with a letter dated February 2, 

2010, from TCEQ requesting approval of a revision to 30 TAC, Chapter 117, Subchapter B, 

Combustion Control at Major Industrial, Commercial, and Institutional Sources in Ozone 

Nonattainment Areas; Division 4, Dallas-Fort Worth Eight-Hour Ozone Nonattainment Area 

Major Sources, Section 117.403(a)(12). The submittal is determined to be administratively 

complete. See pages 5 through 8 of the completeness checklist prepared in conjunction with this 

rulemaking action.

Rule identifiers information is as follows: 

Rule Project No. 2009-023-117-EN 

Exemption of Low Temperature Drying and Curing Ovens in the DFW Ozone Nonattainment 

Area 

Amendments to: §117.403 

Date Adopted: January 13, 2010 

Date Filed with the Secretary of State: January 15, 2010 

Date Published in the Texas Register: January 29, 2010 

Date Effective: February 4, 2010
Page 10 of 14

TCEQ proposed this rule change following a petition from Elk Corporation of Texas. See 34

Texas Register 5976 published August 28, 2009. We originally approved the revisions to 30 

TAC, Chapter 117 Control of Air Pollution from Nitrogen Compounds on December 3, 2008 at 

73 FR 73562. We received a SIP submittal package, with a letter dated May 18, 2011, from 

TCEQ requesting approval of a revision to 30 TAC, Chapter 117, Subchapter B, Combustion 

Control at Major Industrial, Commercial, and Institutional Sources in Ozone Nonattainment 

Areas; Division 4, Dallas-Fort Worth Eight-Hour Ozone Nonattainment Area Major Sources, 

Section 117.403(a)(12). The proposed text of the Section 117.403(a)(12) reads:

§1l7.403. Exemptions.

(a) Units exempted from the provisions of this division (relating to Dallas-Fort Worth EightHour Ozone Nonattainment Area Major Sources), except as specified in §§117.440(i), 

117.445(f)(4) and(9), 117.450, and 117.454 of this title (relating to Continuous Demonstration of 

Compliance; Notification, Recordkeeping, and Reporting Requirements; Initial Control Plan 

Procedures; and Final Control Plan Procedures, for Attainment Demonstration Emission 

Specifications), include the following:

(1) - (11) (No change.)

(12) low-temperature drying and curing ovens used in mineral wool-type fiberglass 

manufacturing and wet-laid, non-woven fiber mat manufacturing in which nitrogencontaining resins, or other [bound chemical] additives are used;

(13) - (16) (No change.)

(b) - (c) (No change.)

That revision to Chapter 117, Subchapter B, Division 4 requires owners or operators of major 

Industrial, Commercial, and Institutional (ICI) sources of NOx in the DFW 1997 eight-hour 

ozone nonattainment area to reduce NOx emissions from a wide variety of stationary sources. 

One source category was curing and drying ovens used in mineral wool-type fiberglass 

manufacturing operations. The December 3, 2008 rulemaking action approved into the Texas 

SIP addition of a new provision under section 117.403(a)(12) to exempt curing ovens used in 
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mineral wool-type fiberglass manufacturing in which nitrogen-bound chemical additives are 

used. Due to technical feasibility issues associated with controlling NOx emissions from ovens 

particularly when wet-laid nitrogen containing resins are used TCEQ was petitioned by a 

fiberglass manufacturer. The petitioner commented that addition of nitrogen-bound chemical 

additives in its operation contributes to the creation of non-combustion-related thermal NOx that 

cannot be controlled using the control technologies State had identified as appropriate for curing 

ovens utilized in mineral wool-type fiberglass manufacturing operations. The amount of NOx 

emitted from curing ovens of this type is estimated to be a small contribution to the total NOX 

emissions from this industry. As a result of granting the petition, approximately 0.1 tons per day 

(tpd) of NOx emission reductions will need to be replaced in the 2007 DFW 1997 8-hour ozone 

attainment demonstration SIP. TCEQ is of the position that the 0.1 tpd of NOx reduction can be 

substituted with 0.1 tpd of NOx from surplus fleet turnover reductions and TCEQ plans to reflect 

this emission credit change in the State’s Discrete Emissions Reduction Credits (DERC) limit 

determination for 2010, consistent with 30 TAC §101.379(1)(2)(A), accordingly. 
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Section 110(l) analysis:

In the 35 Texas Register 6491 issue dated January 29, 2010 TCEQ wrote “The commission 

provides the following information to clarify why the adopted change to expand the exemption in 

§117.403(a)(12) will not negatively impact the status of the state's attainment with the ozone 

National Ambient Air Quality Standard (NAAQS). The requirement for reasonable notice and 

public hearing was satisfied through a public hearing held on September 17, 2009, and the public 

comment period, held from August 28, 2009, to September 28, 2009. The purpose of the hearing 

was to accept written and oral comments on the proposed rulemaking. A written comment was 

submitted by the EPA. The EPA stated that it Will provide comment on the commissions' 

§110(1) demonstration in its comment letter pertaining to the proposed DFW Reasonably

Available Control Technology Update, 30Texas Administrative Code Chapter 117 Rule Revision 
Page 13 of 14

Noninterference Demonstration, And Attainment Demonstration Contingency Plan State 

Implementation Plan Revision. The EPA issued draft guidance on June 8, 2005, titled 

"Demonstrating Noninterference Under Section 110(1) of the Clean Air Act When Revising a 

State Implementation Plan." The Guidance states on page six that "areas have two options 

available to demonstrate noninterference for the affected pollutant(s)." This preamble provides 

details of the identified existing measures that the commission will use to establish compliance 

with option one of the EPA’s guidance: substitution of one measure by another with equivalent 

or greater emissions reduction in air quality benefits.”

To reiterate importance of proper accounting of SIP credits EPA in its August 8, 2011 comment 

letter from Mr. Guy Donaldson of Air Planning Section to Ms. Charlotte Horn of TCEQ’s Texas 

Register Team asked TCEQ to account for and reflect the 0.12 tpd NOx emissions increases 

(0.02 tpd due to the Rule Project No. 2010-048-117-EN plus 0.1 tpd due to the Rule Project No. 

2009-023-117-EN) in the ozone modeling for the DFW 1997 eight-hour ozone nonattainment 

area. See page 9 of the August 8, 2011 EPA’s comment letter.

As stated before, TCEQ is reporting in excess of 7 tpd of surplus NOx reductions (under a 

conservative estimate scenario) for the DFW area from its mobile sources (fleet turnover) that 

would more than compensate the 0.1 tpd increase associated with the low temperature drying 

oven rule project. We believe that by substituting the 0.1 tpd of NOx from the surplus fleet 

turnover emissions reductions the State is, adequately, demonstrating the “non-interference” with 

the maintenance and attainment of NAAQS under section 110(l) of the Act. See the combined 

graph below for illustration comparison purposes. Therefore, State’s submittal meets the 

applicable requirements of the CAA and EPA air quality regulations.
Page 14 of 14

We have reviewed State’s submittal and agree with their reasoning to grant the petition, and thus 

revising section 117.403(a)(12). The above graph compares the NOx emissions increases 

associated with these two rule revisions (0.02 tpd due to the Rule Project No. 2010-048-117-EN

plus the 0.1 tpd due to the Rule Project No. 2009-023-117-EN) vs. the amount of available NOx 

surplus from the DFW fleet turnover credits.

Conclusion: Both revisions to 30 TAC Chapter 117, the February 2, 2010 submittal 

described in section 2 of this TSD; and the May 18, 2011 submittal described in section 1 of this

TSD, should be approved as revisions to the Texas SIP.