Northwest Pipeline LLC Mount Vernon Compressor Station ... · 12/4/2019 · NWP and Ecology discovered the inability of the Predictive Emissions Monitoring System (PEMS) to accurately

Technical Support Document for Prevention of Significant Deterioration Permit No. 01-09, Amendment 7

Northwest Pipeline LLC Mount Vernon Compressor Station Mount Vernon, Washington

December 2019

Publication and Contact Information For more information contact:

Air Quality Program P.O. Box 47600 Olympia, WA 98504-7600 Phone: 360-407-6800

Washington State Department of Ecology — www.ecology.wa.gov

• Headquarters, Olympia 360-407-6000

• Northwest Regional Office, Bellevue 425-649-7000

• Southwest Regional Office, Olympia 360-407-6300

• Central Regional Office, Union Gap 509-575-2490

• Eastern Regional Office, Spokane 509-329-3400

To request ADA accommodation including materials in a format for the visually impaired, call Ecology at 360-407-6800 or visit https://ecology.wa.gov/accessibility. People with impaired hearing may call Washington Relay Service at 711. People with speech disability may call TTY at 877-833-6341.

https://www.ecology.wa.gov/

https://ecology.wa.gov/accessibility

Technical Support Document for Prevention of Significant Deterioration

No. 01-09, Amendment 7

Northwest Pipeline LLC Mount Vernon Compressor Station

Mount Vernon, Washington

Air Quality Program

Washington State Department of Ecology

Olympia, Washington

This page is purposely left blank

v

Table of Contents Page

List of Tables ................................................................................................................................. vi 1. Executive Summary .....................................................................................................................1

2. Prevention of Significant Deterioration in Washington State......................................................2

3. Project and Site Description.........................................................................................................3

3.1. Project description ..............................................................................................................3

3.2. Site description....................................................................................................................3

3.3. PSD permit history ..............................................................................................................3

4. Permit Revision Discussion .........................................................................................................7

4.1. Monitoring frequency .........................................................................................................7

4.2. Portable analyzer accuracy verification ..............................................................................8

4.3. NOX emission limit averaging period for the Sellers C-80-w boiler ..................................8

4.4. Access and sampling ports requirements ............................................................................8

4.5. Operating rate during compliance test for combustion turbine ..........................................9

5. State Environmental Policy Act .................................................................................................10

6. Environmental Justice Review ...................................................................................................11

7. Public Involvement ....................................................................................................................12

8. Agency Contact ..........................................................................................................................13

Acronyms and Abbreviations ........................................................................................................14

vi

List of Tables Page

Table 1: Summary of Revised Project Net Emissions Increase .......................................................4

Table 2: Emission Units Affected by this Permit ............................................................................6

1

1. Executive SummaryNorthwest Pipeline has asked to revise the nitrogen oxide monitoring requirements for the Mars 90S and Centaur 50S combustion turbines at the Mount Vernon Compressor Station. Northwest Pipeline proposes to:

• Monitor nitrogen oxide using portable emission analyzers at least once every 4,380 hours ofturbine’s operation.

• Remove the requirement to verify the accuracy of portable analyzers.

Ecology’s assessment of Northwest Pipeline’s request:

• Approves:

o The proposed monitoring frequency.

o Accuracy verification of the portable analyzers is not needed because there issufficient quality assurance in the test method itself.

• Amendment makes requirements more clear.

• Additional emission testing after each engine exchange.

Northwest Pipeline is a natural gas pipeline that takes gas from western Canada and the Rocky Mountains into Washington. The facility is located about nine miles east of Mount Vernon. The area is designated as meeting national air quality standards (in attainment).

After reviewing Northwest Pipeline’s request, Ecology proposes to approve this request, with an additional requirement. This technical support document shows Ecology’s analysis supporting our decision.

2

2. Prevention of Significant Deterioration inWashington State

PSD permitting requirements in Washington State are established in Title 40, Code of Federal Regulations (CFR) §52.21, Washington Administrative Code (WAC) 173-400-700 through 750. Washington State implements its PSD program as a State Implementation Plan (SIP)-approved program. This SIP-approved program became effective May 29, 2015.1

The objective of the PSD program is to prevent significant adverse environmental impact from emissions into the atmosphere by a proposed new major source, or major modification to an existing major source. The program limits degradation of air quality to that which is not considered “significant.” PSD rules require the utilization of BACT for certain new or modified emission units, which is the most effective air pollution control equipment and procedures that are determined to be available after considering environmental, economic, and energy factors.

PSD rules are designed to keep an area with “good” air in compliance with the NAAQS and Class I requirements. The distinctive requirements of PSD are BACT, air quality analysis (allowable increments and comparison with the NAAQS), and analysis of impacts of the project on visibility, vegetation, and soils.

1 80 FR 23721, April 29, 2015.

3

3. Project and Site Description

3.1. Project description Northwest Pipeline LLC (NWP) has requested revisions to the PSD 01-09, Amendment 6 to revise the nitrogen oxide (NOX) monitoring requirements for the Mars 90S and Centaur 50S combustion turbines. NWP proposes to monitor the NOX emission using portable emission analyzer at least once every 4,380 hours of operation, less frequent than the existing monitoring requirement in the permit. NWP also proposes to remove the requirement to verify the accuracy of portable analyzers.

3.2. Site description NWP operates a natural gas pipeline system from the Washington-Canada border near Sumas, Washington (WA), to the San Juan Gas Fields in New Mexico. The gas pipeline system serves commercial, industrial, utility, and cogeneration customers in Washington, Oregon, Nevada, and California. The Mount Vernon Compressor Station is located at 15498 Lange Road, Mount Vernon, WA 98273, about five miles east of Mount Vernon, WA, and assists in the transport of natural gas from the Sumas Compressor Station to the Snohomish Compressor Station.

This site is:

• About 57 kilometers (km) from the nearest Class I area, North Cascades National Park.

• Within 100 km of four other Class I areas (Alpine Lakes Wilderness, Glacier PeakWilderness, Olympic National Park, and Pasayten Wilderness).

• About 45 kilometers from the U.S.–Canadian border.

• Located within a Class II area that is currently designated in attainment for all national andstate air quality standards

• A major stationary source. The Mount Vernon Compressor Station has potential to emit 390tons per year (tpy) of NOX and 460 tpy of CO.

3.3. PSD permit history

3.3.1. PSD 01-09 The permit authorized the following:

• Adding one Mars 90-TI3002S (Mars 90S) gas turbine site-rated at 12,787 horsepower (59ºF).

• Substituting an existing Centaur 40-T4500 upgraded to a Centaur 50-T6100S (Centaur 50S)at 5,950 hp (59ºF.) for the originally permitted Centaur 40-T4700S (Centaur 40S) gas turbinesite-rated at 4,554 horsepower.

4

• Replacing an existing standby generator with one of larger capacity (450 kW) as originallypermitted.

• Replacing an existing 2.5 million British thermal units per hour (MMBtu/hr) heater/boilerwith one of larger capacity (3.348 MMBtu/hr Sellers C-80-w) as originally permitted.

The project’s net emission of NOX is estimated to be 62.8 tpy. No other pollutant triggered PSD review.

3.3.2. PSD 01-09, Amendment 1 PSD 01-09 was amended because NWP proposed to change the scope of project approved originally. NWP proposed to:

• Install one Mars 90-TI3002S (Mars 90S) gas turbine site-rated at 12,787 horsepower (59° F.)as originally permitted.

• Remove the existing Solar Centaur 40-T4500 permitted under PSD 93-01 and replace it witha larger Solar Centaur 50S rather than keeping the existing turbine and adding anotherCentaur 40S as was originally permitted in PSD 01-09.

• Replacing an existing standby generator with one of larger capacity (450 kW) as originallypermitted.

• Replacing an existing 2.5 MMBtu/hr heater/boiler with one of larger capacity (4.186MMBtu/hr Sellers C100) as originally permitted.

• After completion of one year of operation, it was determined that the parametric monitoringsystem (PEMS) could not provide accurate real time monitoring of emissions from theturbines. WDOE, the NWCAA, and NWP-MVCS subsequently agreed that the PEMSwould be replaced by a monitoring procedure using a portable emission analyzer measuringemissions on a prescribed schedule.

See table below for the summary of the revised project net emissions increase.

Table 1: Summary of Revised Project Net Emissions Increase

Pollutant Emission (tpy)

Nitrogen oxides (NOX) 52.71

Carbon monoxide, (CO) 74.4

Sulfur dioxide, (SO2) 2.26

Volatile organic compounds, (VOCs) 23.24

Particulate matter less than 10 micrometers in diameter (PM10) 4.64

5

3.3.3. PSD 01-09, Amendment 2 NWP and Ecology discovered the inability of the Predictive Emissions Monitoring System (PEMS) to accurately predict real-time emissions. This finding was based upon completion of one year of PEMS data gathering and analysis, and Ecology agreed with NWP. There was no change to emission limits in the second amendment as well. Therefore, public notice was not required.

3.3.4. PSD 01-09, Amendment 3 To implement changes requested by NWP that clarified and streamlined the permit. There were no changes to the emission limits in this amendment. Therefore, public notice was not required.

3.3.5. PSD 01-09, Amendment 4 To revise the emissions testing frequency for the boiler (Seller C-80-w with heat input of 3.348 MMBtu/hr) and standby generator. NWP requested that Ecology change the permitted frequency of NOX performance tests from an annual basis to every five years starting from the date of the most recent compliance test.

At their fully allowed operating time, NOX emissions from the standby generator and the boiler together are less than three-quarters of a ton per year. Ecology agreed that a once every five years emissions test for these small emission units was satisfactory to assure air quality protection.

3.3.6. PSD 01-09, Amendment 5 To allow a reduction in the required frequency of NOX routine monitoring testing. A portable emissions analyzer is used for these routine monitoring tests. More than three years of testing every 14 days had shown that testing every 28 days was sufficient to monitor compliance. There were no changes to emission limits in Amendment 5.

3.3.7. PSD 01-09, Amendment 6 To clarify and simplify NOX monitoring and reporting procedures used by portable NOX monitors in preparation for renewal of the facility’s Title V permit. Testing using a portable analyzer to monitor the volume percent of NOX every 336 hours has proven adequate to indicate compliance, so the additional calculation of NOX mass flow during these periodic tests is no longer required. If noncompliance is indicated by a portable monitor test, the turbine will now be shut down as soon as reasonably possible and repaired rather than have further emissions testing. No compliance testing conditions for NOX (reference Method 20) are affected by these changes, but the NOX limit’s averaging time is reduced from a three- to one-hour time period, which is more stringent.

3.3.8. Affected emission units The emission units affected by this permit are listed below.

6

Table 2: Emission Units Affected by this Permit

Emission Unit Description Design Capacity

Solar Mars 90-T13002S gas turbine 100.3 MMBtu/hr @ 59°F

Solar Centaur 50-T6100S gas turbine 54.93 MMBtu/hr @ 59°F

Sellers C-80-W water heater/boiler 3.35 MMBtu/hr

Caterpillar-G3412, emergency electrical generator 450 kW

7

4. Permit Revision DiscussionEcology reorganizes and streamlines the permit conditions, including removing the obsolete languages with this permit revision. The original condition language in PSD 01-09, Amendment 6 is included as attachment to this technical support document for ease of comparing the changes. Some of the more significant and noteworthy changes are discussed below.

4.1. Monitoring frequency Based on the existing permit requirements, Mars 90S and Centaur 50S combustion turbines are subject to NOX emission limit of 25 parts per million on a dry volumetric basis (ppmdv) over a 1-hour average when corrected to 15.0 percent oxygen, ISO. EPA RM20 determines compliancewith the emission limit, and the testing frequency is no later than 13 months after the previoustest.

In addition to reference method test, the permit also requires that NWP monitor the NOX concentration at least once every 336 hours of turbine operation using portable analyzer. If six consecutive monitoring results show that the NOX concentration is below the emission limit, the monitoring frequency can be reduced to at least once every 672 hours of turbine operation.

NWP proposes to monitor the NOX emission using portable emission analyzer at least once every 4,380 hours of operation. As part of the information received for this permit amendment, Ecology learned from the facility’s monitoring result that the monitored NOX concentration exceeded the limit during 2015 and 2016 on three occasions. On each occasion, NWP concluded that the cause of exceedance is pilot settings for horsepower were not properly established following the engine exchange. The exceedances resulted in approximately 998 pounds of NOX excess emissions (from facility’s Title V Statement of Basis) offer some perspective for the potential impact from the mass emission rate standpoint.

Considering the size of the turbines and relatively low excess emission rate if exceedance did occurred, Ecology finds that annual compliance demonstration using EPA reference method and occasional monitoring using portable analyzer should be sufficient to ensure compliance. However, in addition to monitor the emission using portable analyzer at least once every 4,380 hours of operation, Ecology finds that NWP shall also demonstrate compliance using reference method after each engine exchange because the past historical events indicates that the exceedance could occur after the exchange. If engine exchange occurs within the same annual test frequency period, the reference test conducted after engine exchange can be used to satisfy annual compliance test requirement.

To offer a context of how often engine exchange could occur, Ecology has obtained the following information from NWP. During 2018, the Centaur 50S operated for 2,859 hours and Mars 90S operated for 6,747 hours. The turbines are generally exchanged once every 25,000 to 30,000 hours of operation. An exchange may occur sooner if a mechanical problem that cannot be addressed on-site is discovered with the turbine.

8

Ecology believes that this monitoring approach is practical and is sufficient to ensure that the combustion turbines meet the NOX emission limit.

4.2. Portable analyzer accuracy verification NWP also proposes to remove the requirement to conduct accuracy verification of the portable analyzer. The existing permit condition requires NWP to develop a protocol to verify the accuracy of the portable analyzer and conduct the accuracy test each calendar year. To verify the accuracy, NWP compares the measured concentration using portable analyzer to the concentration determined by independent lab using reference methods.

Ecology agrees to remove the accuracy verification requirements. Ecology finds that this requirement is unnecessary since Conditional Method 34 consists of repeatability check that ensure that the accuracy shall not vary more than ± 3 percent or ± 1 ppm, and is sufficient to ensure good measurement results for the monitoring purpose.

4.3. NOX emission limit averaging period for the Sellers C-80-w boiler For the Sellers C-80-w boiler, the existing NOX concentration limit is 34 ppmdv over a 24-hour average corrected to three percent oxygen. Compliance with the NOX emission concentration limit shall be determined in accordance with 40 CFR 60 Appendix A, Methods 7E and 19.

Ecology is revising the averaging period for the NOX concentration limit to 3-hour from 24-hour basis for the following reasons:

• The averaging period will be more consistent with the standard reference test as compliancedemonstration method.

• From the original PSD permit application, it appears that this limit was established based onthe vendor’s provided emission information. However, vendor did not provide any averagingperiod for the emission data. This emission appears to be established based on vendor’sprovided information without taking into consideration of the averaging period forcompliance demonstration purpose.

4.4. Access and sampling ports requirements This permit revision removes Condition 7 of PSD 01-09, Amendment 6. The condition requires NWP to provide access and sampling ports for testing. Ecology finds that it is unnecessary to include this condition in the PSD permit since WAC 173-400-105(4) and Appendix A of 40 CFR 60 provide equivalent requirements. These requirements are currently included in the facility’s Title V Permit (AOP).

9

4.5. Operating rate during compliance test for combustion turbine The existing permit condition did not address what should be the operating rate of the combustion turbine during annual compliance test. Ecology finds that it is important to require the combustion turbine to operate at representative maximum operating rate during the annual compliance test for compliance demonstration purpose. Therefore, this expectation is added to condition No. 14 through this amendment. Representative maximum operating rate means approximately ± 10 percent of the highest operating rate achieved during the calendar year of the compliance test.

10

5. State Environmental Policy ActThe Skagit County issued a State Environmental Policy Act (SEPA) Determination of Nonsignificant (DNS) on May 21, 2002, originally for the project. The proposal does not change the scope that was covered under the original SEPA determination. The revised permit conditions also is not expected to have additional environmental impact.

Ecology will incorporated the original SEPA DNS issued by reference for this action.

11

6. Environmental Justice ReviewEnvironmental justice (EJ) is the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. Ecology conducts an EJ review to ensure no group of people bear a disproportionate share of the negative environmental consequences as the result of the permitting action.

Ecology finds that the EJ review is not needed because there is no emission increase as the consequences of this permitting action.

12

7. Public InvolvementThis PSD permitting action was subject to a minimum 30-day public comment period under WAC 173-400-740. Ecology posts the public notice on Ecology's web site for a minimum of 30 days. Day one of the public comment period begins on the next calendar day after Ecology posts the public notice.

13

8. Agency ContactMengChiu Lim, P.E. Washington State Department of Ecology Air Quality Program P.O. Box 47600 Olympia, WA 98504-7600 [email protected]

mailto:[email protected]

14

Acronyms and Abbreviations °F degrees Fahrenheit

BACT Best Available Control Technology

CFR Code of Federal Regulations

CO carbon monoxide

DNS Determination of Nonsignificant

Ecology Washington State Department of Ecology

EJ Environmental Justice

EPA United States Environmental Protection Agency

km kilometers

kW kilowatt

MMBtu million British thermal units per hour

NAAQS National Ambient Air Quality Standards

NOX nitrogen oxides

NWCAA Northwest Clean Air Agency

NWP Northwest Pipeline LLC

PEMS Predictive Emissions Monitoring System

PM particulate matter

PM10 particulate matter less than 10 micrometers in diameter

ppm parts per million

ppmdv parts per million on a dry volumetric basis

PSD Prevention of Significant Deterioration

SEPA State Environmental Policy Act

SO2 sulfur dioxide

tpy tons per year

VOC volatile organic compound

WAC Washington Administrative Code

WASHINGTON STATE DEPARTMENT OF ECOLOGY POST OFFICE BOX 47600

OLYMPIA, WASHINGTON 98504-7600

IN THE MATTER OF: ]]

Northwest Pipeline Corporation ] NO. PSD-01-09 Amendment 6 Mount Vernon Compressor Station ] Williams Gas Pipeline–West ] FINAL APPROVAL 295 Chipeta Way ] OF PSD APPLICATION Salt Lake City, UT 84158-0900 ]

This approval is issued pursuant to the United States Environmental Protection Agency (EPA) regulations for the Prevention of Significant Deterioration (PSD) set forth in Title 40, Code of Federal Regulations, Part 52, and regulations set forth in the Washington Administrative Code (WAC) 173-400-700. The original approval was based upon the complete application submitted by Williams Gas Pipeline–West for the Northwest Pipeline Corporation (NWP) Mount Vernon Compressor Station on December 4, 2001. The first amendment was based on a letter of request dated April 23, 2004. The second and third amendments were based on letters of request dated April 23 and July 21, 2004, respectively. The fourth, fifth, and sixth amendments were based on letters of request dated September 20, 2004; February 8, 2006; and October 18, 2011, respectively. The technical analysis performed by the Washington State Department of Ecology (Ecology) finds the following:

FINDINGS

1. The reason for the sixth administrative amendment is to clarify and simplify NOX monitoringand reporting procedures used by portable NOX monitors in preparation for renewal of thefacility’s Title V permit. Testing using a portable analyzer to monitor the volume percent ofNOX every 336 hours has proven adequate to indicate compliance, so the additionalcalculation of NOX mass flow during these periodic tests is no longer required (ApprovalCondition 5.1.6.1). If noncompliance is indicated by a portable monitor test, the turbine willnow be shut down as soon as reasonably possible and repaired rather than have furtheremissions testing (Approval Condition 5.1.6.1.3). No compliance testing conditions for NOX(reference Method 20) are affected by these changes, but the NOX limit’s averaging time isreduced from a three- to one-hour time period, which is more stringent. No physical changesare requested.

2. The reason for the fifth administrative amendment was to allow a reduction in the requiredfrequency of nitrogen oxides (NOX) routine monitoring testing. A portable emissionsanalyzer is used for these routine monitoring tests. More than three years of testing every 14days had shown that testing every 28 days was sufficient to monitor compliance. There wereno changes to emission limits in Amendment 5.

3. The reason for the fourth administrative amendment was to address NWP’s request for lessfrequent emissions testing for the boiler (Seller C-80-w with heat input of 3.348 MMBtu/hr)

Northwest Pipeline Corporation Page 2 of 13 Mount Vernon Compressor Station PSD-01-09 Amendment 6 February 16, 2012

and standby generator. NWP requested that Ecology change the permitted frequency of NOX performance tests from an annual basis to every five years starting from the date of the most recent compliance test. At their fully allowed operating time, NOX emissions from the standby generator and the boiler together are less than three-quarters of a ton per year. Ecology agreed that a once every five years emissions test for these small emission units was satisfactory to assure air quality protection.

4. The reason for the third administrative amendment was to implement changes requested byNWP that clarified and streamlined the permit. There were no changes to the emission limitsin this amendment. Therefore, public notice was not required.

5. The reason for the second amendment was that NWP and Ecology discovered the inability ofthe Predictive Emissions Monitoring System (PEMS) to accurately predict real-timeemissions. This finding was based upon completion of one year of PEMS data gathering andanalysis, and Ecology agreed with NWP. There was no change to emission limits in thesecond amendment as well. Therefore, public notice was not required.

6. NWP owns and operates the existing Mount Vernon Compressor Station (MVCS) locatedabout nine miles east of Mt. Vernon, Washington (48oN 25' 19" latitude, 122oW 12'58"longitude).

7. MVCS is located within a Class II area that is currently designated in attainment for allnational and state air quality standards. PSD permit 01-09 allowed an expansion to thisfacility described in Findings 10 through 23 below.

8. The site is 57 kilometers (km) from the nearest Class I area, North Cascades National Park,and within 100 km of four other Class I areas (Alpine Lakes Wilderness, Glacier PeakWilderness, Olympic National Park, and Pasayten Wilderness).

9. The site is about 45 kilometers from the U.S.–Canadian border.10. This project consists of:

10.1. Adding one Mars 90-TI3002S (Mars 90S) gas turbine site-rated at 12,787 horsepower (59ºF).

10.2. Substituting an existing Centaur 40-T4500 upgraded to a Centaur 50-T6100S (Centaur 50S) at 5,950 hp (59ºF.) for the originally permitted Centaur 40-T4700S (Centaur 40S) gas turbine site-rated at 4,554 horsepower.

10.3. Replacing an existing standby generator with one of larger capacity (450 kW) as originally permitted.

10.4. Replacing an existing 2.5 million British thermal units per hour (MMBtu/hr) heater/boiler with one of larger capacity (3.348 MMBtu/hr Sellers C-80-w) as originally permitted.

11. This project is subject to New Source Performance Standards (NSPS): 40 CFR Subpart GG(Standards of Performance for Stationary Gas Turbines).

Northwest Pipeline Corporation Page 3 of 13 Mount Vernon Compressor Station PSD-01-09 Amendment 6 February 16, 2012 12. The emissions of all air pollutants from the proposed modification are subject to review

under Chapter 173-400 WAC, Chapter 173-460 WAC, and the regulations of the Northwest Clean Air Agency (NWCAA). Chapter 173-400 WAC includes provision for PSD review (WAC 173-400-700). This permit considers only PSD-applicable issues. All other air quality related notice of construction approval issues are subject to the NWCAA.

13. MVCS currently has the potential to emit more than 250 tons per year (TPY) of any one pollutant that is subject to the federal Clean Air Act. This qualifies MVCS as an existing major stationary source. Any net increases in potential emissions from the site that are considered significant will be subject to PSD review under WAC 173-400-700.

14. Because of this project, the net increase in MVCS's potential to emit nitrogen oxides (NOX) is 62.8 TPY.

15. Because MVCS is an existing major stationary source, and the net emissions increase for NOX is more than 40 TPY, the project qualifies as a major modification. As a result, the project is subject to PSD review under WAC 173-400-700. Additionally, the project is subject to federal PSD review because it qualifies as a major modification under federal rules [40 CFR 52.21(b)(2)(i), 40 CFR 52.21(b)(3)(i), and 40 CFR 52.21(b)(23)(i)].

16. Other than NOX, the net emissions increases of all pollutants subject to regulation under the federal Clean Air Act are below the significance levels specified in 40 CFR 52.21(b)(23)(i). As a result, they are not subject to inclusion in this PSD permit.

17. The PSD permit application was submitted December 4, 2001, and determined to be complete on January 3, 2002.

18. MVCS will operate the standby generator fewer than 500 hours in any calendar year. The limit will be federally enforceable under the conditions of this PSD permit.

19. The Mars 90S turbine, the Centaur 50S turbine, the standby generator, and the heater/boiler being installed for this project will burn only natural gas from the pipeline.

20. Best Available Control Technology (BACT) determinations for NOX emissions: 20.1. Dry low-NOX control (SoLoNOX) for the Mars 90S and Centaur 50S turbines. 20.2. Nonselective catalytic reduction for the standby generator. 20.3. Good combustion practice for the Sellers C-80-w heater/boiler.

21. Allowable emissions from the new emissions units will not cause or contribute to air pollution in violation of: 21.1. Any ambient air quality standard. 21.2. Any applicable maximum allowable increase over the baseline ambient concentration. 21.3. National Ambient Air Quality Standards (NAAQS) and PSD increment consumption:

Modeling to determine impacts was not required because the applicant demonstrated the impacts to be below modeling significance thresholds.


21.4. Visibility impact in the surrounding Class I areas: The highest modeled impact was a 4.8 percent degradation, which occurred in North Cascades National Park in mid-winter. Federal land manager guidance considers this to be below the "concern" threshold.

21.5. Visibility impact in nearby Class II parks and recreational areas: The highest modeled impact in Mt. Baker Wilderness was 6.2 percent degradation in mid-winter, and less than four percent the rest of the year. Federal land manager guidance considers this acceptable under PSD procedures and BACT requirements.

22. Ambient impact analysis indicates that there will be no significant pollutant deposition onsoils and vegetation in the Class I or Class II areas.22.1. Modeled emissions ambient impact levels are substantially below all secondary

NAAQS. This indicates a low likelihood of negative impact on Class II area flora and fauna. No sensitive species have been identified.

22.2. NWP has agreed with the Washington Department of Fish and Wildlife to conduct a nesting survey for bald eagles expected to be near the facility.

22.3. The highest modeled nitrogen deposition in the surrounding Class I areas is less than 50 percent of the "concern" threshold in federal land manager guidance.

23. No significant effect on industrial, commercial, or residential growth in the Mt. Vernon,Washington, area is anticipated because of this project.

Ecology finds that all requirements for PSD have been satisfied. Approval of the PSD application is granted subject to the following conditions.

APPROVAL CONDITIONS

1. The Mars 90S turbine, the Centaur 50S turbine, the standby generator, and the heater/boilerbeing installed for this project:1.1. Are only allowed to burn natural gas from the pipeline.1.2. NWP shall monitor and report (see Condition 8) the analytical data from the Sumas

monitor location regarding the chemical composition of the fuel used to comply with Condition 1.1.

2. The standby generator:2.1. NWP shall operate the standby generator no more than 500 hours in any consecutive

12-month period.2.2. NWP shall monitor compliance with Condition 2.1 with:

2.2.1. An hour meter for generator operation. 2.2.2. NWP shall not reset the hour meter without written authorization of Ecology or

NWCAA.


2.3. NOX emissions from the standby generator are limited to not greater than 82 grams per hour.

2.4. NWP shall demonstrate initial compliance with Condition 2.3: 2.4.1. Within 180 days after initial start-up, NWP will have a source test performed by

an independent testing firm. 2.4.2. The run-time on the standby generator for the initial compliance demonstration

test shall not count toward the operating time limit in Condition 2.1. 2.4.3. The source test shall be in accordance with 40 CFR 60 Appendix A, Methods 2,

2A, 2C, or 2D, and Method 7E. 2.4.4. For the source test, NWP shall run the generator at maximum achievable load. 2.4.5. NWP shall determine the emissions rate in units of grams per hour by using the

source test results in applicable engineering calculations. 2.4.6. NWP shall submit a test plan to Ecology and NWCAA for approval at least 30

days prior to testing. 2.4.7. Within 90 days of initial start-up, NWP will confirm to Ecology in writing that

the existing standby generator has been taken out of service. 2.5. NWP shall monitor compliance with Condition 2.3 by periodic NOX emission

performance tests: 2.5.1. NWP shall conduct NOX emission performance tests not less frequently than once

every 500 hours of operation. 2.5.2. NWP may conduct the periodic performance tests by use of a portable emission

analyzer verified as accurate in accordance with the process outlined in Condition 6.

2.5.2.1. Testing shall be in accordance with USEPA Designated Conditional Test Method 34. An alternate test method may be used if approved in writing by Ecology or NWCAA at least 30 days prior to its first application.

2.5.2.2. NWP shall follow the currently approved performance test procedure until acquiring approval from Ecology or NWCAA for a revised procedure.

2.5.2.3. For the source test, NWP shall run the generator at maximum achievable load.

2.5.3. NWP shall determine the emissions rate in units of grams per hour by using the source test results in applicable engineering calculations.

3. The 3.348 MMBtu/hr Sellers C-80-w boiler:3.1. The NOX emissions concentration from the boiler stack is limited to not greater than

34 parts per million on a dry volumetric basis (ppmdv) over a 24-hour average when corrected to three percent oxygen.


3.2. NWP shall demonstrate initial compliance with Condition 3.1: 3.2.1. Within 180 days after initial start-up, performed by an independent testing firm. 3.2.2. By source test in accordance with 40 CFR 60 Appendix A, Methods 7E and 19. 3.2.3. NWP shall submit a test plan to Ecology and NWCAA for approval at least 30

days prior to testing. 3.2.4. Within 90 days of initial start-up, NWP will confirm to Ecology in writing that

the existing 2.5 MMBtu/hr heater/boiler has been taken out of service. 3.3. NWP shall monitor compliance with Condition 3.1 by periodic NOX emission

performance tests: 3.3.1. NWP shall conduct NOX emission performance tests not less frequently than once

every five years of operation. 3.3.2. NWP may conduct the periodic performance tests by use of a portable emissions

analyzer capable of adjustment to the three percent oxygen concentration basis, and verified as accurate in accordance with the process outlined in Condition 6.

3.3.2.1. Testing shall be in accordance with USEPA Designated Conditional Test Method 34. An alternate test method may be used if approved in writing by Ecology or NWCAA at least 30 days prior to its first application.

3.3.2.2. NWP shall follow the currently approved performance test procedure until acquiring approval from Ecology or NWCAA for a revised procedure.

3.4. NOX emissions from the boiler are limited to not greater than: 3.4.1. Four lb/calendar day. 3.4.2. 0.66 tons in any 12 consecutive months.

3.5. NWP shall monitor compliance with Condition 3.4 by: 3.5.1. Keeping a log of the operating hours for the boiler, and 3.5.2. Using the following to determine the mass NOX emissions:

3.5.2.1. The most recent performance test results intended to satisfy Condition 3.3.1.

3.5.2.2. Assume maximum achievable fuel consumption for all boiler operating hours.

3.5.2.3. Use the appropriate F-factor from 40 CFR Part 60, Appendix A Method 19 to estimate exhaust gas volumetric flowrate.

4. For the Mars 90S and Centaur 50S combustion turbines: 4.1. Start-up is defined as any operating period that is ramping up from less than 90

percent of full load, and less than 15 minutes has elapsed since fuel was introduced to the turbine after the immediately preceding shutdown.


4.2. Shutdown is defined as any operating period below 90 percent of full load, and fuel feed has continued for not more than 15 minutes after going below 90 percent of full load operation.

4.3. NWP shall keep a record of each start-up and shutdown event. 5. Emissions of nitrogen oxides (NOX) for the combustion turbines are limited as follows:

5.1. For the Mars 90 combustion turbine:5.1.1. Not greater than 25 parts per million NOX emission concentration on a dry

volumetric basis (ppmdv) over a 1-hour average when corrected to 15.0 percent oxygen, ISO.

5.1.2. Condition 5.1.1 is relieved during start-up and shutdown. 5.1.3. Mass emissions of NOX shall not exceed:

5.1.3.1. 258 lb NOX/calendar day. 5.1.3.2. 43.6 tons of NOX for any consecutive 12-month period.

5.1.4. NWP shall count NOX emissions during start-up and shutdown toward monitoring compliance with the 12-month mass emission limit in Condition 5.1.3.2 at a rate of 4 lb NOX per start-up or shutdown.

5.1.5. NWP shall demonstrate compliance with Conditions 5.1.1 and 5.1.3.1 initially and annually thereafter:

5.1.5.1. Initial compliance shall be demonstrated within 180 days after initial start-up, performed by an independent testing firm. Annual compliance shall be demonstrated no later than 13 months after the previous test.

5.1.5.2. Compliance shall be demonstrated in accordance with 40 CFR 60 Subpart GG and 40 CFR 60 Appendix A, Method 20 except that the instrument span shall be reduced as appropriate.

5.1.5.3. NWP shall submit a test plan to NWCAA for approval at least 30 days prior to testing. NWP shall submit a complete test report to the NWCAA no later than 60 days after completion of the tests.

5.1.6. Compliance monitoring: 5.1.6.1. NWP shall monitor compliance with Condition 5.1.1 by measuring NOX

concentration from each turbine exhaust stack no less frequently than every 336 hours of turbine operation.

5.1.6.1.1. NWP may conduct these measurements by use of a portable emissions analyzer capable of adjustment to the 15 percent oxygen concentration basis, and verify as accurate in accordance with the process outlined in Condition 6.

5.1.6.1.2. Portable emissions analyzer testing shall be in accordance with USEPA Designated Conditional Test Method 34. An alternate test


method may be used if approved in writing by Ecology prior to the test.

5.1.6.1.3. NWP shall perform three consecutive tests using the portable analyzer. Should the average of the three test results indicate potential noncompliance with Condition 5.1.1, NWP shall shut down the unit as soon as is practical and contact the NWCAA as promptly as possible and in no event more than 12 hours later. Exceedance of the limit imposed by Condition 5.1.1 as indicated by the average of the three consecutive tests shall be prima facie evidence of a violation of Condition 5.1.1.

5.1.6.1.4. Upon submission of six consecutive months monitoring results during which every test using the portable emissions analyzer indicates compliance with Condition 5.1.1 for a given turbine, NWP may submit a request that the testing frequency for that turbine be reduced to not less frequently than every 672 hours of operation. The request must include an analysis of the accuracy of the portable emissions analyzer using recent accuracy verification data and an analysis of the portable emissions data collected during the monitoring period and an explanation as to why these data support the request. Upon Ecology’s approval of the request, NWP may test at the reduced frequency until such time as the results indicate potential noncompliance with Condition 5.1.1. If this occurs, NWP must revert to the 336 hour testing frequency for the turbine in potential noncompliance with Conditions 5.1.1 for at least six consecutive months at which time NWP may again request the reduced testing frequency using the same process as above.

5.1.6.2. Within 20 days of the end of each month, pursuant to Condition 5.1.3.2, NWP shall determine the tons of NOX emissions from each of the turbines for the most recent consecutive 12 months. For this calculation, NWP shall utilize a time-weighted average of the relevant reference method stack test results wherein the results of each source test shall be the presumed emission rate until the next source test.

5.2. For the Centaur 50S combustion turbine: 5.2.1. Not greater than 25 parts per million NOX emissions concentration on a dry

volumetric basis (ppmdv) over a 1-hour average when corrected to 15.0 percent oxygen, ISO.

5.2.2. Condition 5.2.1 is relieved during start-up and shutdown. 5.2.3. Mass emissions of NOX shall not exceed

5.2.3.1. 106 lb NOX/calendar day. 5.2.3.2. 18.5 tons of NOX for any consecutive 12-month period.


5.2.4. NWP shall count emissions during start-up and shutdown towards monitoring compliance with the 12-month mass emission limit in Condition 5.2.3.2 at a rate of 2 lb NOX per start-up or shutdown.

5.2.5. NWP shall demonstrate compliance with Conditions 5.2.1 and 5.2.3.1 initially and annually thereafter:

5.2.5.1. Initial compliance shall be demonstrated within 180 days after initial start-up, performed by an independent testing firm. Annual compliance shall be demonstrated no later than 13 months after the previous test.

5.2.5.2. Compliance shall be demonstrated in accordance with 40 CFR 60 Subpart GG and 40 CFR 60 Appendix A, Method 20, except that the instrument span shall be reduced as appropriate.

5.2.5.3. NWP shall submit a test plan to NWCAA for approval at least 30 days prior to testing. NWP shall submit a complete test report to the NWCAA no later than 60 days after completion of the tests.

5.2.6. Compliance monitoring: 5.2.6.1. NWP shall monitor compliance with Condition 5.2.1 by measuring the

NOX concentration from each turbine exhaust stack no less frequently than once every 336 hours of turbine operation.

5.2.6.1.1. NWP may conduct these measurements by use of a portable emissions analyzer capable of adjustment to the 15 percent oxygen concentration basis, and verify as accurate in accordance with the process outlined in Condition 6.

5.2.6.1.2. Portable emissions analyzer testing shall be in accordance with USEPA Designated Conditional Test Method 34. An alternate test method may be used if approved in writing by Ecology prior to the test.

5.2.6.1.3. NWP shall perform three consecutive tests using the portable analyzer. Should the average of the three test results indicate potential noncompliance with Condition 5.2.1, NWP shall shut down the unit as soon as is practical and contact the NWCAA as promptly as possible and in no event more than 12 hours later. Exceedance of the limit imposed by Condition 5.2.1 as indicated by the average of the three consecutive tests shall be prima facie evidence of a violation of Condition 5.2.1.

5.2.6.1.4. Upon submission of six consecutive months’ monitoring results during which every test using the portable emissions analyzer indicates compliance with Condition 5.2.1 for a given turbine, NWP may submit a request that the testing frequency for that turbine be reduced to not less frequently than every 672 hours of operation.


The request must include an analysis of the accuracy of the portable emissions analyzer using recent accuracy verification data and an analysis of the portable emissions data collected during the monitoring period and an explanation as to why these data support the request. Upon Ecology’s approval of the request, NWP may test at the reduced frequency until such time as the results indicate potential noncompliance with Condition 5.2.1. If this occurs, NWP must revert to the 336 hour testing frequency for the turbine in potential noncompliance with Condition 5.2.1 for at least six consecutive months at which time NWP may again request the reduced testing frequency using the same process as above.

5.2.6.2. Within 20 days of the end of each month, pursuant to Condition 5.2.3.2, NWP shall determine the tons of NOX emissions from the turbine for the most recent consecutive 12 months. For this calculation, NWP shall utilize a time-weighted average of the relevant stack test results wherein the results of each source test shall be the presumed emission rate until the next source test.

6. NWP shall verify the accuracy of any portable emissions analyzers used to satisfy themonitoring requirements of this permit.6.1. NWP shall submit a protocol to Ecology and NWCAA for written approval by

Ecology for verifying the accuracy of any portable emissions analyzer. 6.2. NWP shall use the procedure specified in the protocol required by Condition 6.1 to

verify the accuracy of any portable emissions analyzer prior to its use in satisfaction of the monitoring requirements of this permit.

6.3. Not less than once every calendar year, NWP shall use the procedure specified in the protocol required by Condition 6.1 to verify the accuracy of any portable emissions analyzer intended to be used in satisfaction of the monitoring requirements of this permit.

6.4. NWP shall keep records of the emissions analyzer accuracy verifications for not less than five years for Ecology and NWCAA review.

7. NWP shall provide safe access and sampling ports for source testing of the standbygenerator, the heater/boiler, the Mars 90S turbine, and the Centaur 50S turbine beinginstalled for this project, after each final pollution control device:7.1. Safe access for the standby generator and the heater/boiler shall consist of not less

than a man-lift or situation-specific scaffolding.7.2. Safe access for the Mars 90S turbine, the Centaur 50S turbine shall consist of

permanently constructed platforms on the respective stacks.7.3. The sampling ports shall meet the requirements of 40 CFR, Part 60, Appendix A,

Method 20.


7.4. Other arrangements may be acceptable if approved by Ecology prior to installation. 8. NWP shall report the monitoring and process data from MVCS to Ecology and NWCAA as

follows: 8.1. Notifications:

8.1.1. Commencement of construction of the project described in Finding 10 of this permit: In accordance with 40 CFR 60.7(1), no later than 30 calendar days after such date.

8.1.2. Initial start-up of the project described in Finding 10 of this permit: In accordance with 40 CFR 60.7(3), no later than 15 calendar days after such date.

8.1.3. Completion of the entry into the operation and maintenance manual of the items specified in Condition 9.

8.1.4. In the first quarterly report required under Condition 8.2, certification by the responsible party for the facility that the relevant equipment was installed consistent with the parameters developed pursuant to Condition 9.

8.2. Submit reports not less than once each calendar quarter or on another reporting schedule approved by Ecology, and in the format approved by Ecology.

8.3. The reports shall include, but not necessarily be limited to, the following: 8.3.1. Certification by the responsible party for the facility that only natural gas from the

pipeline has been used as fuel. 8.3.2. Analytical data on the fuel composition per Condition 1.2. 8.3.3. Certification by the responsible party for the facility that the relevant equipment

was operated and maintained in accordance with the operational parameters and practices developed pursuant to Condition 9.2.

8.3.4. For the standby generator: 8.3.4.1. Total hours of operation for the 12 immediately preceding months. 8.3.4.2. The total NOX mass emissions for the 12 immediately preceding months. 8.3.4.3. Results of any compliance monitoring source tests performed since the last

report. 8.3.5. For the 3.348 MMBtu/hr Sellers C-80-w boiler:

8.3.5.1. The total NOX mass emissions for the 12 immediately preceding months. 8.3.5.2. Results of any compliance monitoring source tests performed since the last

report. 8.3.6. For each combustion turbine stack:

8.3.6.1. All exhaust stack NOX concentrations since the last report pursuant to measurement under Conditions 5.1.6.1 and 5.2.6.1.


8.3.6.2. The total NOX mass emissions for the 12 immediately preceding months ending with each month included in the report.

8.3.6.3. Results of any compliance monitoring source tests received since the last quarterly report including verification of the accuracy of NOX concentration portable analyzers emissions allowed in Conditions 2.5.2, 3.3.2, 5.1.6.1.1, and 5.2.6.1.1. If reported separately, these results need not be duplicated in the quarterly reporting.

8.3.6.4. For each occurrence of NOX monitored emissions pursuant to measurement under Conditions 5.1.6.1 and 5.2.6.1 in excess of the limits in Conditions 5.1.1 or 5.2.1:

8.3.6.4.1. The time of the occurrence. 8.3.6.4.2. Magnitude of the emission or process parameters excess. 8.3.6.4.3. The duration of the excess. 8.3.6.4.4. The probable cause. 8.3.6.4.5. Corrective actions taken or planned. 8.3.6.4.6. Any other agency contacted.

8.4. NWP shall maintain MVCS monitoring and process records for at least five years. 8.4.1. NWP shall inform Ecology and NWCAA on the location of the monitoring and

process records. 8.4.2. NWP shall provide Ecology and NWCAA with the monitoring and process

records for any period within the 5-year archive within 10 working days of request.

8.4.3. The monitoring and process records maintained in the 5-year archive shall include, but not necessarily be limited to, the following:

8.4.3.1. Fuel monitoring records pursuant to Condition 1.2. 8.4.3.2. Operating time records pursuant to Condition 2.2. 8.4.3.3. Operating hours records pursuant to Condition 3.5.1. 8.4.3.4. Record of start-ups and shutdowns for the Mars 90S and Centaur 50S

turbines pursuant to Condition 4.3. 9. An Operation and Maintenance (O&M) manual for the facility:

9.1. Within 90 days of start-up, NWP shall identify operational parameters and practicesfor MVCS.

9.1.1. The operational parameters and practices will constitute proper operation relative to compliance with the emission limitation conditions of this permit.

Documents

Northwest Pipeline LLC Mount Vernon Compressor Station ... · 12/4/2019 · NWP and Ecology discovered the inability of the Predictive Emissions Monitoring System (PEMS) to accurately